HORNO MAERZ

INSTRUCTION MANUAL

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BOOK-1

GENERAL INSTRUCTION & OPERATION

AK685 – CALQUIPA S.A.C. Callalli, Peru F2S - 300/400 tpd MAERZ finelime kiln (coal / opt.gas)

Document No. Revision Revision Date / saved on Author Based on template edition

© Maerz Ofenbau AG Richard Wagner-Strasse 28 CH-8027 Zürich Switzerland

AK685_971.01 0 06 January 2014 Patrick Ewert 14-1 / MRZTD.DOT

Telefon: +41 44 287 27 27 Telefax: +41 44 201 36 34 E-Mail: [email protected] www.maerz.com

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GENERAL INSTRUCTION & OPERATION

Table of Contents 1

BASIC INFORMATION

9

1.1

About this instruction manual

9

1.2

Terminology

9

1.3

Reference material

9

1.4

Explanation of signs and symbols

10

1.4.1 1.4.2

Signs and symbols used in the manual Safety labels and signs on plant equipment

10 10

1.5

Liability and warranty

16

1.6

Copyright protection

16

1.7

Transport, Packaging and Storage

17

1.7.1 1.7.2 1.7.3

Safety notes Transport inspection Packaging

17 18 18

1.8

Spare parts

19

1.9

Storage

19

1.10

Disassembly

20

1.11

Waste disposal

20

2

SAFETY

21

2.1

General

21

2.2

Responsibility of the plant operator

22

2.3

Intended use

23

2.4

Workers' safety

23

2.5

Personal safety equipment (PSE)

24

2.6

Possible dangers at the plant

25

2.7

Emergency process stop

28

2.7.1 2.7.2 2.7.3

Staff and kiln protection Emergency process stop system Emergency stop switch reset

28 28 29

2.8

Operating personnel

30

2.9

Conduct in dangerous situations and in case of accidents

30

2.10

Danger areas

32

2.11

Noisy areas

34

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GENERAL INSTRUCTION & OPERATION

3

TECHNOLOGICAL PRINCIPLE

37

3.1

Useful literature

37

3.2

Calcination of limestone and dolomite

37

3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.2.7 3.2.8 3.2.9 3.2.10

Limestone Formation of limestone Mineralogical composition Impurities Mineral structure and grain size Porosity and density Bulk density and particle size Thermal dissociation of carbonate Mechanical strength and abrasion resistance Data and properties of limestone

37 37 37 38 39 39 40 40 41 42

3.3

Calcination of limestone

43

3.3.1 3.3.2 3.3.3 3.3.4 3.3.5

Thermal decomposition of calcium carbonate Physical-chemical phenomena during calcination Reactivity of quicklime Influence of feed size on retention time Lime to limestone factor

43 44 47 48 50

3.4

Fuel

51

3.4.1 3.4.2 3.4.3 3.4.4 3.4.5

Definition of calorific values Combustion air volume (v’ol) Wobbe index Heat flow Fuel data

52 52 52 53 53

4

DESIGN AND FUNCTIONING (TYPE FS)

55

4.1

Design

56

4.2

Design

58

4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6 4.2.7 4.2.8 4.2.9

Parallel-flow firing system Preheating the combustion air Two-shaft kiln Burner lances Reversing devices Charging device Discharge device Hydraulic system Kiln refractory lining

58 58 58 59 59 60 61 62 62

4.3

Functional description

63

4.3.1 4.3.2

Special requirements of limestone calcination Process description

63 63

4.4

Characteristic data

66

4.4.1 4.4.2

Grain size of charged limestone Operating cycles

66 66

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GENERAL INSTRUCTION & OPERATION

4.4.3 4.4.4

Heat and mass flow Temperature profile

67 68

4.5

Kiln control system

69

4.6

Electric switchboard

70

4.6.1 4.6.2 4.6.3

Main components Safety information Additional documents

70 73 73

4.7

Local operation panel

74

4.7.1

Main components

74

4.8

Instrumentation

76

4.8.1 4.8.2 4.8.3 4.8.4

General description Arrangement of instruments Wiring diagrams Purpose of the most important measuring instruments

76 76 76 76

5

COMMISSIONING

81

5.1

General information / Definition

81

5.2

Requirements for cold commissioning

82

5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6 5.2.7 5.2.8

Consumables Lubricating points Shaft construction Refractory Kiln systems Electrical installations / instrumentation Firing system Waste gas filter

82 82 83 85 85 85 86 86

5.3

Cold commissioning

87

5.3.1 5.3.2 5.3.3 5.3.4 5.3.5

Suspended cylinder (if existent) Components Software Integration test Charging the kiln with limestone:

87 87 87 87 88

5.4

Hot commissioning

89

5.4.1

Process adjustments

89

5.5

Conclusion of the commissioning

89

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GENERAL INSTRUCTION & OPERATION

6

OPERATION

91

6.1

General

91

6.2

Safety

91

6.3

Visualization system

95

6.3.1 6.3.2 6.3.3 6.3.5 6.3.6 6.3.7 6.3.8 6.3.9

Screen layout Color definitions User level Parameter tables Process pictures Alarms Tuning screens Trend messages

96 99 101 102 105 120 124 125

6.4

Theoretical Basis of Lime Kiln Operation

127

6.4.1 6.4.2 6.4.3 6.4.4 6.4.5

Modes of operation Filling mode Heating mode Production mode “charging during reversal time” Production mode “charging during burning time”

127 127 128 128 129

6.5

Reversal and charging sequences

130

6.5.1 6.5.2

Production mode “charging during the reversal time” Production mode “Charging during burning time”

130 133

6.6

Calculation of the process parameters (sample)

135

6.7

Description of the Operational Procedures

137

6.7.1 6.7.3 6.7.4 6.7.5

Limestone charging Filling the kiln Start-up process Production operation

137 138 139 145

6.8

Preconditions for production operation

147

6.8.1 6.8.2 6.8.3 6.8.4 6.8.5 6.8.6 6.8.7 6.8.8 6.8.9

Basic recommendations Key factors for the lime burning process in the lime kiln Adjustment of the cooling air Setting the Heat Input Adjusting the Air Excess Factor Setting the Fuel Parameters Setting the Reversal Time Setting the Nominal Burn-out Time Setting the discharge tables

147 147 147 148 148 150 150 150 151

6.9

Kiln stoppage and restarting

152

6.9.1 6.9.2 6.9.3 6.9.4 6.9.5

Kiln stoppage Restarting Kiln stoppage by an alarm Kiln stoppage in the case of a power cut Emptying the kiln

152 153 154 155 155

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6.10

Fine Lime Charging

157

6.10.1 6.10.2 6.10.3

Effect on lime quality Distribution system Kiln charging method

157 158 158

7

MALFUNCTION

165

7.1

Safety

165

7.2

Steps to be taken in the event of a failure

166

7.3

Alarm systems

167

7.3.1 7.3.2

Failure of machine components Failure of the machine's control system

168 168

7.4

Restart after failure

169

7.5

Steps for troubleshooting

169

8

MAINTENANCE

175

8.1

In general

175

8.2

Safety

176

8.3

Lubricating instruction

176

8.4

Maintenance schedule

177

8.4.1

Check list

177

8.5

After maintenance

188

9

INDEX

189

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1

Basic information

1.1

About this instruction manual

GENERAL INSTRUCTION & OPERATION Basic information

This instruction manual describes the design, start-up, operation, and maintenance of the kiln plant. Compliance with all safety notes and directives specified is a precondition for safe working with and proper handling of the plant. Furthermore, all specific local accident prevention regulations and general safety rules must be strictly observed. This instruction manual is an essential part of the product. At least one copy must be kept in the kiln plant control room at all times. It must be accessible to the operating, maintenance, and cleaning personnel. The illustrations in this manual are meant for better understanding and are not necessarily true to scale. The contents of the manual may vary from the version of the actual plant. For more precise and detailed information, the respective drawings and diagrams must be kept on hand. In addition, the individual documents and instructions related to the installed components and equipment will apply. Strictly observe the notes contained therein especially safety notes.

1.2

Terminology The terms "plant" or "kiln” used in this manual refer to the Maerz® Parallel Flow Regenerative Shaft Kilns for Limestone and Dolomite. Some views in this manual, the PI diagrams, as well as other documents and drawings use identifiers and tag numbers to refer to a specific component installed. The term "operating company" is used to relate to the "plant owner". The term "operator" however is used strictly to refer to the "operating person" to the "kiln attendant".

1.3

Reference material Unless otherwise specified, the individual components of the kiln plant are purchased from other manufacturers than MAERZ. All components used in the plant have been tested and subjected to risk assessment by the respective manufacturers. The manufacturers of these components have confirmed the compliance of the equipment with applicable European and national regulations. The declarations of conformity of the manufacturers as well as operating, maintenance, and repair instructions for the various plant components are integral parts of the overall documentation. The directives on safety, setup and installation, operation, preventive maintenance, disassembly and disposal of the components included in the manufacturers' documentation must be strictly observed by all personnel involved.

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1.4

Explanation of signs and symbols

1.4.1

Signs and symbols used in the manual

GENERAL INSTRUCTION & OPERATION Basic information

Important safety and technical notes in this operating manual are marked with symbols. These notes must be adhered to in order to avoid accidents, personal injuries and damage to property. WARNING This symbol stands for dangers that can lead to adverse effects on health, injuries, permanent physical damage, or death. Absolutely adhere to the notes regarding safety at work, and be particularly careful in this respect. DANGER OF ELECTRIC CURRENT This symbol draws attention to dangerous situations involving electrical currents. There is the risk of serious injuries or death if the safety notes are not complied with. Any work is to be carried out by qualified electricians only. CAUTION This symbol stands for dangers that can lead to adverse effects on health, injuries, or physical damage. NOTICE This symbol indicates notes, which if not complied with can lead to damage, malfunctions and/or breakdown of the plant. INFORMATION This symbol highlights tips and information to be observed for efficient and trouble-free operation of the plant. 1.4.2

Safety labels and signs on plant equipment The following table lists all mandatory signs, prohibition, warning, fire, and rescue labels attached to plant equipment. WARNING The safety labels below indicate prohibitions, dangers, and directives. Strictly comply with these safety labels. Failure to observe any of them may lead to death, serious injury, or damage to the plant.

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GENERAL INSTRUCTION & OPERATION Basic information

Prohibition labels Prohibition labels are white and contain a crossed-out black symbol surrounded by a red circle. Smoking prohibited Risk of fire caused by combustible or explosive solid, liquid, or gaseous materials. Do not touch, live housing Danger caused by electric shock. Fire, open light, and smoking prohibited Do not introduce or generate any kind of ignition source, such as: - open flames and hot gases (e.g. burning candles, matches, welding beads, welding sparks, or gleaming charcoal) - warm / hot surfaces (e.g. radiators, hot plates, light bulbs, crankcases, exhaust systems) - frictional heat (e.g. hot bearings) - mechanically generated sparks (e.g. rock, concrete, metal sparks produced by grinding, abrasive cutting, or hammer strokes) Fire extinguishing with water prohibited Water may prove to be unsuitable for extinguishing fires and may further increase the danger caused by fire Authorized personnel only Access to the danger area is limited to authorized persons (personnel authorized by the plant operator to enter the danger area). Do not touch Containers or parts may become damaged when touched. Prohibition Used in combination with another sign specifying the prohibition

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GENERAL INSTRUCTION & OPERATION Basic information

Mandatory signs Mandatory signs are blue and contain a white symbol.

Wear safety goggles

Wear hearing protection

Wear safety shoes

Wear safety clothing

Wear safety harness

Wear safety hat

Wear breathing mask

Wear safety gloves

Wear face screen

Switch off before beginning work

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GENERAL INSTRUCTION & OPERATION Basic information

Warning signs Warning signs are yellow and contain a black symbol. Warning of inflammable materials

Warning of a danger area

Danger of tripping and falling

Warning of gas bottles

Warning of explosive atmosphere

Danger of crushing

Warning of automatic start

Warning of hand injuries

Warning of dangerous voltage

Warning of hot surface

Warning of toxic materials

Warning of chemical burns

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GENERAL INSTRUCTION & OPERATION Basic information

Fire labels Fire labels are red and contain a white symbol.

Fire hose

Fire fighting equipment

Directional arrow (only to be used in combination with another fire label)

Ladder

Fire alarm box

Fire fighting facility

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GENERAL INSTRUCTION & OPERATION Basic information

Rescue signs Rescue signs are green and contain a white symbol.

First aid

Stretcher

Eye rinsing facility

Emergency phone

Arrow pointing to first-aid facilities (only to be used in combination with another first aid symbol)

Rescue paths and emergency exits

Emergency path

Emergency path

Emergency exit

Emergency exit

Emergency exit

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1.5

GENERAL INSTRUCTION & OPERATION Basic information

Liability and warranty All specifications and information used in this instruction manual are provided in consideration of all applicable regulations, the current state of the art, and our longstanding expertise and experience. For special designs and order-specific configurations or, in the event of technical changes, the actual scope of supply may deviate from the described specifications and provided drawings and sketches. Please contact MAERZ if you have any questions. INFORMATION Carefully read this instruction manual before starting any work at or with the plant and, in particular, before first-time operation. MAERZ cannot assume any liability for damage or failures caused by the non-observance of the instructions provided in this instruction manual. We reserve the right to introduce technical modifications to the product with the intention to improve and further develop the useful properties of the plant. Components, such as tools that are subject to normal wear and tear during standard operation of the kiln, as well as commodities, such as greases, oils, or detergents, are excluded from the warranty. The obligations agreed upon in the supply contract, the terms and conditions, as well as the manufacturer’s terms of delivery, and all legal requirements applicable at the time of conclusion of the contract remain in full effect.

1.6

Copyright protection The instruction manual is to be treated confidentially. It is exclusively intended for persons working on and with the plant. Leaving the instruction manual to a third party without written approval of the manufacturer is not permitted. Please contact MAERZ in case of any questions. INFORMATION The contents, text, drawings, illustrations, and other presentations contained in this manual are protected by copyright and subject to additional commercial property rights. Any misuse is punishable by law. Copying by use of any type and format – even in excerpts – as well as the use and/or publication of the contents is not permitted without written approval by MAERZ. Infringements are liable to damage compensation. Additional claims are reserved.

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1.7

GENERAL INSTRUCTION & OPERATION Basic information

Transport, Packaging and Storage INFORMATION The installation and initial operation of the kiln must only be performed by employees of the manufacturer or by persons authorized by him to perform such tasks. However, the installation and further use of the kiln may require that employees of the operator be entrusted with the task of handling packing units. When performing such tasks, make sure to observe the information provided below:

1.7.1

Safety notes WARNING Danger of injury! There is a danger of injury due to falling parts when lifting, swinging, and lowering materials. The machine can be damaged or destroyed by improper transport. For this reason, basically observe the following safety notes: Always use appropriate lifting tackle and slinging devices with sufficient carrying capacity. Only secure the machine on the fastening points provided; do not fasten at projecting machine parts or eyelets of attached components. Make sure the slinging device is secure! Ropes and belts must be equipped with safety hooks. Do not use torn or worn ropes. Do not lay ropes and belts on sharp edges and corners, do not knot or twist. Pay attention to the centre of gravity of the equipment when fastening the tackle. Never lift, swing, or lower loads over people. Always move the equipment with utmost care and attention. WARNING Risk of death! Suspended loads can fall down and lead to severe injuries. Do not stand or pass under suspended loads when transporting with lifting tackle!

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1.7.2

GENERAL INSTRUCTION & OPERATION Basic information

Transport inspection Check delivered goods immediately on receipt for completeness and transport damage. Do not accept the delivery or only accept under reserve if there is externally recognizable transport damage. Note the scope of damage on the transport documents/delivery note of the carrier. Start complaints procedure. Register complaint about hidden deficiencies as soon as they are discovered, as indemnity claims can only be asserted within the applicable time for complaints.

1.7.3

Packaging INFORMATION Keep environmental protection in mind! Packaging materials are valuable raw materials and can continue to be used in many cases, or can be suitably reconditioned and recycled. If there is no return agreement for packaging, sort materials according to type and size, and route them for further use or recycling. NOTICE Always dispose of packaging materials in an environmentally friendly manner and in accordance with the applicable, local disposal guidelines. If necessary, order a recycling company.

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1.8

GENERAL INSTRUCTION & OPERATION Basic information

Spare parts Use only spare parts authorized by the manufacturer of the relevant equipment. NOTICE Wrong or faulty spare parts can lead to damage, malfunctions, or total failure of the plant. All claims for warranty, service, damage compensation, as well as liability claims against the manufacturer or his representatives, dealers and agents become void when unauthorized spare parts are used.

1.9

Storage Keep packed goods in this state until installation, and store such items as specified by the externally attached installation and storage information. Store packing units only under the following conditions: - Do not keep in the open air. - Store in dry and dust-free environment. - Do not subject to aggressive media. - Protect against direct sunlight. - Avoid mechanical vibration. - Storage temperature: 15 to 25°C - Relative humidity: max. 60% - For longer periods of storage (>3 months), check the general condition of all parts and the packaging at regular intervals. If necessary touch up or renew conservation. INFORMATION Refractory magnesite stones may absorb moisture from the surrounding air and chemically react with this moisture. If the stones are stored for more than 3 months, this reaction may cause damage to the magnesite stones, even if the storage information provided above is observed. It is therefore recommended to store impregnated stones only.

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1.10

GENERAL INSTRUCTION & OPERATION Basic information

Disassembly For disassembly, the plant must be cleaned and dismantled in strict compliance with the applicable industrial safety regulations and accident prevention instructions. WARNING Danger of injury! Stored residual energies, sharp edged components, pointed corners and edges on and inside the plant or on the required tools can cause severe injuries. Any disassembly work on the plant is therefore to be carried out by skilled personnel only.

Before starting disassembly: - Shut down the plant and secure it against restarting. - Physically disconnect the complete energy supply from the plant, and properly discharge stored residual energies. - Dispose of fuels and lubricants as well as residual processing materials in an environmentally acceptable manner.

1.11

Waste disposal If no agreement concerning retrieval or waste disposal has been made, disassembled components must be passed on for recycling after correct dismantling: - Metal material residues must be scrapped - Plastic elements must be forwarded for recycling of plastics - Other components must be sorted by material properties NOTICE Electric scrap, electronic components, lubricants and other auxiliary materials must be treated as hazardous waste and must only be disposed of by specially approved waste disposal companies!

Remove operating materials like greases, oils, preservation agents and detergents from the plant, separate by type, and dispose of in an environmentally responsible manner. In this process, use collection and storage containers that are suitable and approved for the respective operating materials. Clearly mark containers; provide information about contents, filling level and date, store until final disposal so that improper use is impossible.

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2

GENERAL INSTRUCTION & OPERATION Safety

Safety This section provides an overview of all important safety aspects for optimal protection of personnel against any danger and ensures safe and trouble-free operation of the plant. In addition, specific notes on safety to avert danger are provided and marked with symbols in the individual chapters. All pictograms, signs, and labels on the plant are to be strictly observed and kept legible at all times.

2.1

General The plant has been manufactured according to generally accepted engineering standards applicable at the time of its development, and production and is considered operationally safe. However, the plant may entail dangers, if not used properly or according to its intended purpose by professionally trained personnel. Therefore, any person commissioned to work on or with the plant must have read and understood the “Instruction Manual” before commencing work. It is recommended that the company operating the plant should request concrete proof that the personnel have taken full knowledge of the instruction manual's contents. Modifications of any type as well as attachments or changes to the plant without written authorization by Maerz are prohibited. All safety, warning and operating notes affixed to the plant or any of its components must always be kept legible. Damaged signs or stickers are to be replaced without delay. Specified settings or ranges of operating parameters must be observed by all means.

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2.2

GENERAL INSTRUCTION & OPERATION Safety

Responsibility of the plant operator - Store the instruction manual in the direct vicinity of the kiln and keep it readily available for the erection, operating, maintenance and cleaning personnel at all times. - Do not operate the lime kiln plant unless it is in proper technical condition and operationally safe. - Keep safety devices accessible at all times and check proper functioning on a regular basis. All information regarding safety at work refers to the guidelines issued by the European Union applicable at the time the kiln was manufactured. The plant operator is responsible for ensuring that while the kiln is in operation, the specified work safety regulations comply with the latest updates of all applicable current and future regulations. Outside the territory of the European Union, the plant operator must comply with all work safety laws as well as with all regional laws and regulations applicable at the place of operation. In addition to the information regarding safety at work specified in this instruction manual, the plant operator must also follow and comply with all regulations regarding general safety, accident prevention, and protection of the environment applicable at the place of operation. The plant operator and any personnel authorized by him are responsible for the trouble-free operation of the kiln as well as for assigning unambiguous responsibilities with regard to the installation, operation, maintenance and cleaning of the kiln. The information provided in this instruction manual must be followed in full and without limitation. The plant operator has the obligation to attach signs limiting access to the kiln to trained and authorized personnel. In accordance with this instruction manual, the plant operator must also attach warning signs or plates at all access points to the kiln, informing of the dangers involved with working at and with the kiln. The plant operator must provide a sufficient number of fire-fighting equipment inside the kiln area. The plant operator must equip the personnel working at the kiln with sufficient and suitable first-aid equipment. The personnel must be trained in handling first-aid equipment. The plant operator must familiarize his personnel with the recommendations provided by the "International Chemical Safety Cards" for handling calcium oxide, fuels, and other dangerous materials, and the personnel must adhere to these recommendations.

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2.3

GENERAL INSTRUCTION & OPERATION Safety

Intended use Safety and reliability of the equipment is only guaranteed if it used as intended in accordance with the information provided in the instruction manual. The intended use of the lime kiln is the production of quicklime in accordance with specifications. The kiln may only be operated with the fuel specified in the chapter Technical Data. NOTICE Any use of the system, beyond or different from the intended one, is prohibited and considered not as intended. Claims of any kind against the manufacturer and/or his authorized representatives resulting from damage caused by use of the kiln not as intended are excluded. The customer/plant operator is solely liable for any damage caused by a use other than intended. Intended use also includes correct adherence to erection, operating, maintenance and cleaning instructions.

2.4

Workers' safety Follow the safety instructions to prevent persons and property from becoming injured or damaged during the operation of the kiln. Failure to observe this information represents a serious risk of injury to the personnel and may cause damage to or the destruction of the kiln, especially if the kiln is operated in an explosive environment. The manufacturer or his agents shall not be liable for any defects caused by failure to observe these safety instructions.

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2.5

GENERAL INSTRUCTION & OPERATION Safety

Personal safety equipment (PSE) Operation, maintenance, troubleshooting/fault elimination/repairs and cleaning work require wearing a personal protective outfit. The plant operator must make sure that all persons involved in work with or at the kiln have the required protective equipment at their disposal and wear it for work. Operating persons and expert personnel occupied with work at the kiln are obliged to wear their personal safety equipment before and during work. In principle, the following items are to be worn when working on or with the plant: Tight-fitting work clothing minimal tear strength, no wide sleeves, no rings or other jewellery, etc. Safety goggles to protect the eyes against liquids and particles flying about Face screen to protect the eyes and the face against flames, sparks, or embers as well as hot particles or emissions Breathing mask to protect against inhaling particles or emissions Safety shoes to protect against heavy parts being dropped, and slipping on slippery surfaces Safety gloves to protect the skin against friction, excoriation, pricking and deeper injuries on the hands and against contact with health affecting substances Safety helmet to protect against objects and materials falling down or flying around Ear defenders to protect against hearing damage

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2.6

GENERAL INSTRUCTION & OPERATION Safety

Possible dangers at the plant The plant has been subjected to risk assessment. The resulting construction and design of the plant correspond to the state of the art. Nonetheless, some risks remain. The plant works with high pressure hydraulic oil Any damage to the hydraulic system may result in a strong stream of liquid. WARNING Risk of injury Danger caused by liquids spurting out under high pressure. Wear personal safety equipment when working at the kiln. The plant works with electrical voltage DANGER OF ELECTRIC CURRENT Electrical power can cause severe injuries. There is imminent danger to life and health caused by electrical current if the insulation or individual components are damaged. - Disconnect the main switch, and secure against switching on again before maintenance, cleaning, or repair work. - Switch off the power supply before starting work in the electrical system and make sure that the system is dead. - Do not remove any safety features or do not modify such installations in a way that would affect their function. The plant works with movable components WARNING Risk of injury Rotating and/or linearly moving components can cause severe injuries. Do not reach with your hands into or touch moving parts during operation. Do not open covers and maintenance flaps. - Allow components to run out after switching off the plant. - Before starting cleaning, repair, maintenance, or any other work, wait until all components have stopped, switch off the plant and reliably secure against being switched on again. - After cleaning, repair, maintenance, or any other work, close and lock all covers, maintenance flaps, etc.

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GENERAL INSTRUCTION & OPERATION Safety

The plant comprises pneumatic components WARNING Risk of injury Pneumatic energies can cause severe injuries. In case of damage to individual components, operating media can escape under high pressure and cause injuries and material damage. Therefore: - Always relieve the system from any pressure before starting work on pneumatic equipment. - Do not remove or inhibit any safety facilities. - Do not adjust pressure levels beyond the limits specified in the instruction manual. The plant has sharp edges and corners CAUTION Risk of injury Sharp-edged housing parts and sharp corners can cause grazes on the skin. Wear protective gloves when working at the plant. The kiln works with powerful fans WARNING Risk of injury The fast-running impeller installed inside the blower may cause serious injuries such as cutting or severing of body parts. Therefore: - Do not operate the blowers, unless the impeller cage, protection caps, and maintenance covers are closed. - Prior to performing any work at the blower, shut down the unit, secure it against re-starting, and keep it closed until all running components have come to a complete stop. - Do not open the impeller cage, protection caps, and maintenance covers until the impeller has come to a complete stop. Afterwards, secure all moving components against uncontrolled movements by appropriate means such as clamping.

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GENERAL INSTRUCTION & OPERATION Safety

Operation of the kiln may release highly flammable materials WARNING Risk of injury Highly flammable materials, liquids, and/or gases might catch fire and cause serious injuries. - Smoking, handling open light, fire, and/or sources of ignition of all kinds in the vicinity of the kiln and within a distance of 5 m or less is strictly prohibited. - Locate any suspicious materials, liquids and gases, and notify your superior without delay. - Stop working immediately. Leave the danger zone, until the all-clear is given. The kiln works with CaO (quicklime) WARNING Risk of chemical burns caused by CaO There is a risk of sustaining chemical burns in places labeled accordingly. Any person working inside these areas must proceed with great caution when handling caustic materials. In addition to the danger of damaging one's clothing, there is also the risk of burning one's eyes, skin and possibly one's mucous membranes. Burning one’s eyes may cause irreparable visual impairment. When handling caustic materials, wear personal safety equipment as required by the Chemical Safety Datasheet. The plant operator must keep available at all times rinsing liquids for cleaning eyes. When burnt lime is mixed with water it reacts by generating a lot of heat and thus becoming leach. The kiln works under high pressure WARNING Risk of injury The kiln is operated under pressure. Flames or hot gases may spurt out when any access or inspection doors are opened. The high pressure inside the kiln may cause the kiln doors to fly open with great force. Do not open the kiln doors until the pressure difference between the inside and the outside of the kiln is zero.

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2.7

Emergency process stop

2.7.1

Staff and kiln protection

GENERAL INSTRUCTION & OPERATION Safety

To protect the kiln and the staff working at it, the kiln is equipped with an emergency process stop system comprising emergency process stop buttons and safety locks. The emergency process stop system is a category 1 system with one-channel disconnection. The emergency process stop and safety features of the kiln control system are fully integrated into this emergency system, which is equipped with its own controller. The operating, cleaning, service and maintenance personnel must be instructed about the location and the functionality of the safety devices on a regular basis. Proof of such instruction must be provided upon request. 2.7.2

Emergency process stop system The entire emergency process stop system consists of an emergency process stop sequence. This means that as soon as the emergency process stop button has been pushed or the safety lock has been engaged, the entire kiln will immediately be set to a safe operating mode. The safe operating mode is either achieved by immediately interrupting the power supply to the drives, by shutting down the drives until they have come to a complete stop, or by moving them into a safe position until the power is cut off with a delay. For kilns with suspended cylinders NOTICE The operating process requires the cooling system of the suspended cylinders to continue to run, even if the emergency process stop function has been activated. Do not turn off the cooling system of the suspended cylinders as otherwise the suspended cylinders, and consequently the kiln, may become heavily damaged. In the event of a failure of the cooling system of the suspended cylinders, activate the emergency cooling system without delay. If the operation of the cooling system for the suspended cylinders poses a danger to the kiln operating person, immediately shut down the kiln by pushing the emergency process stop button. However, make sure to manually activate the emergency cooling system directly after shutting down the kiln.

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2.7.3

GENERAL INSTRUCTION & OPERATION Safety

Emergency stop switch reset WARNING Risk of injury Any uncontrolled re-starting of the kiln may cause serious personal damage. Prior to re-starting the kiln or any of its components, check whether the cause of the emergency process stop has been eliminated, and make sure that all safety devices have been re-installed and are properly functioning. After having successfully reset the triggered contact (e.g. by rotating and unlocking the emergency process stop button), proceed by acknowledging the emergency process stop.

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2.8

GENERAL INSTRUCTION & OPERATION Safety

Operating personnel The kiln may only be operated and maintained by authorized, qualified and instructed personnel. These personnel must have received special instructions regarding any dangers that may occur. Instructed personnel have been taught about the tasks entrusted to them and the possible dangers resulting from improper actions, and if necessary, have been instructed practically in this respect. Moreover, the personnel have been informed of the required protective features and protective measures. Qualified personnel are persons who can assess the work entrusted to them and recognize potential dangers based on their special training, expertise, and experience as well as on their knowledge of appropriate conditions. If staff members do not have the necessary knowledge, they are to be trained accordingly. Responsibilities for operation and maintenance must be clearly determined and adhered to so that there is no unclear division of competence with regard to safety. The kiln may only be operated and maintained by persons who can be expected to carry out their work reliably. This means that any mode of operation that affects the safety of persons, of the environment or the kiln is to be avoided. Persons who are under the influence of drugs, alcohol, or medication that affects their responsiveness may under no circumstances carry out work on or with the kiln plant. When selecting personnel, attention must be paid to the regulations protecting young workers in the relevant country regarding the minimum age and, if necessary, to the job-related instructions based on this. The operating company must ensure fully that only authorized persons work on or with the kiln plant. All non-authorized persons, such as visitors etc., must at any time be kept at an appropriate safety distance to the kiln and any of its ancillary equipment. The operating personnel are obliged to immediately report to the plant operator or his representative any safety-relevant incidents in kiln operation.

2.9

Conduct in dangerous situations and in case of accidents Always be prepared for accidents or fire. In a dangerous situation or in case of an accident, stop the kiln by immediately activating the EMERGENCY PROCESS STOP SWITCH. The EMERGENCY PROCESS STOP SWITCH may only be operated in emergency situations and must not be used for normal kiln stops. Keep first-aid equipment (first-aid kit, eye rinsing bottle, etc.) and fire extinguisher close to hand. Personnel must be acquainted with the location and handling of safety equipment, accident reporting facilities, first-aid and rescue equipment. This will enable them to avert dangers and provide the best possible help in case of accidents.

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2.10

GENERAL INSTRUCTION & OPERATION Safety

Danger areas

Fig. 1

Danger areas (typical)

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GENERAL INSTRUCTION & OPERATION Safety

Item

Description

1

Reversal flap (filter / direct chimney)

2

Reversal flap (combustion air / waste gas)

3

Shaft closing flap

4

Thermal radiation and heat on kiln shaft

5

Access doors and inspection openings to kiln

6

Lime belt conveyor

7

Lime vibrating feeder

8

Lime discharge hopper

9

Discharge flap

10

Discharge table

11

Air blast unit (not shown)

12

Poking hole

13

Emergency venting for suspended cylinder cooling system

14

Relief flap combustion air (not shown)

15

Stone distribution flap

16

Rotating bucket

17

Reversible belt conveyor

18

Limestone vibrating feeder

Additional danger areas (not shown) Hydraulic unit and hydraulic system Blowers and ventilators Limestone belt conveyor Waste gas filter All stairs and platforms

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2.11

GENERAL INSTRUCTION & OPERATION Safety

Noisy areas

Fig. 2

Noisy areas (typical)

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GENERAL INSTRUCTION & OPERATION Safety

Item

Description

~LAeq [dBA]

1

Chimney exit

80

2

Reversal flap

70

3

Relief flap combustion air (not shown)

105

4

Relief flap cooling air (not shown)

95

5

Lime vibrating feeder

90

6

Discharge flap and hopper

90

7

Discharge table

85

8

Emergency fan for suspended cylinder

100

9

Air blast unit (not shown)

95

10

Emergency venting suspended cylinder cooling system

100

11

Kiln charging

95

12

Rotating bucket

105

13

Limestone feeder

95

14

Stone hopper

105

Additional noisy areas (not shown) Description

~LAeq [dBA]

Hydraulic unit

90

Blower house internal

110

Blower house external

75

Transport system for limestone and lime

105

Waste gas filter

85

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3

Technological Principle

3.1

Useful literature

GENERAL INSTRUCTION & OPERATION Technological Principle

- Boynton, R.S., "Chemistry and Technology of Lime and Limestone" John Wiley &. Sons, 1980, ISBN 0-471-02771-5. - Oates, J.A.H., "Lime and Limestone" Wiley-VCH, 1998, ISBN 3-527-29527-5 - European Commission, "Integrated Pollution Prevention and Control (IPPC)" Reference Document on Best Available Techniques in the Cement and Lime Manufacturing Industries (adopted Dec 2001) - Schiele, E., Berens L.W., "Kalk – Herstellung, Eigenschaften, Verwendung" (in German), Stahleisen m.b.H., 1972, ISBN 3-514-00115-4

3.2

Calcination of limestone and dolomite

3.2.1

Limestone Limestone is found widely throughout the world and is an essential raw material for many industries.

3.2.2

Formation of limestone Limestone is one of the most widely distributed sedimentary rocks throughout the world. Commercially used limestone is mainly of organic origin. Deposits were formed by the building-up of fossiliferous marine sediments in oceans consisting of shells and skeletons of plants and animals. Some of these sediments were deposited by natural chemical reaction. Calcium bicarbonate was produced by the extremely slow dissolution of calcium carbonate fossils through the solvent action of carbon dioxide, which was subsequently re-precipitated in carbonate form. Layer by layer of these deposits form massive beds of limestone.

3.2.3

Mineralogical composition Limestone and dolomite can be composed of the following four minerals, characterized by the following physical data: Chemical formula

Molecular weight

Specific gravity 3 [g/cm ]

Hardness [Mohs Scale]

Crystal system

Calcite

CaCO3

100.1

2.71

3.0

rhombohedral

Aragonite

CaCO3

100.1

2.94

3.5-4.0

orthorhombic

Dolomite

CaMg(CO3)2

92.2

2.84

3.4-4.0

rhombohedral

Magnesite

MgCO3

84.3

3.00

5.0-4.5

rhombohedral

Dolomite and calcite play the main role as industrial minerals. - Pure limestone (calcite and aragonite) is 100% calcium carbonate. - Pure dolomite contains 54.3% CaCO3 and 45.7% MgCO3 (30.4% CaO, 21.8% MgO, and 47.8% CO2).

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GENERAL INSTRUCTION & OPERATION Technological Principle

INFORMATION Limestone and dolomite used for industrial purposes include: - Pure calcite with 97–99% CaCO3 - Pure dolomite with 40–43% MgCO3 and 57–60% CaCO3 Impurities in these limestone and dolomite rocks are usually between 1 and 3%. 3.2.4

Impurities Impurities in limestone are classified as homogeneous and heterogeneous. Silica and alumina - Homogeneous impurities such as clay, silt, sand, and other forms of silica like quartz are well dispersed throughout the formation. - Heterogeneous impurities, which are found, for example, as siliceous pieces or nodules of sand, chert or flint are loosely embedded in the limestone. Iron - The third major impurity is homogeneously distributed after the limestone has started to form iron carbonate by chemically replacing calcium with iron. This frequently occurs in oolitic limestone. - It is heterogeneously distributed as iron sulphide or iron oxide in minerals like pyrite, limonite, and hematite. Phosphorous and sulphur - They usually occur only in small quantities. Manganese, copper, titanium - These and further impurities are virtually negligible and considered as trace elements in the pure stone.

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3.2.5

GENERAL INSTRUCTION & OPERATION Technological Principle

Mineral structure and grain size Limestone is crystalline. The grain size (to be distinguished from particle size) increases with the amount of re-crystallization that has occurred during the formation of the deposit. The crystalline structure varies greatly in density and hardness. Micro

250 × 10-6 m (up to about 1000 × 10-6 m)

The particle shape depends partly on the microstructure of the grain, but also on the crushing characteristics of the crushing machine. NOTE Cubic or spherical shapes of limestone particles are usually preferred for lime kilns. Avoid processing layered or flat limestone particles whenever possible. 3.2.6

Porosity and density The porosity of limestone particles varies considerably depending on the degree of compaction and structure of the limestone. It is defined as the ratio of the void volume Vv and the total volume Vtot. The void volume Vv comprises both accessible and inaccessible pores. The figure below illustrates different kinds of pores.

Fig. 3

Different kinds of pores (typical)

Item

Description

1

solid pore

2

inaccessible pore

3

accessible pore

Density is defined as the ratio of mass m and volume V of a particular particle. The solid or specific density (D) considers the volume of the pure solid without any void volume.

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The apparent density (Ds) considers the volume of the solid with the inaccessible space. The apparent porosity (Ps) describes the accessible volume as the difference of that part of the specific density minus the apparent density with the amount of inaccessible space.

 D  Ps  1  s   100 D  Ps = Apparent porosity [%] Ds = Apparent density D = Specific density Some data regarding apparent porosities and apparent densities of commonly used types of limestone is provided in the table below. Industrial limestone shows a wide range of apparent porosities (0.1 to 40%) and densities (1.50 to 2.90 g/cm3) caused by the different forming conditions and levels of re-crystallization.

3.2.7

3

Apparent porosity [%]

Apparent density [g/cm ] dried at 110 °C

Dense limestone

0.1 to 3.0

up to 2.7

Marble

0.1 to 2.0

2.7 to 2.8

Chalk

15 to >40

1.5 to 2.3

Bulk density and particle size Bulk density is the mass per unit volume of a solid, including the voids in a bulk sample of the material. Bulk density depends largely on the apparent density of the limestone, its particle size distribution, and on the particle shape. Crushed, screened limestone with a size ratio of 2:1 generally has a bulk density of 1.3 to 1.6 g / cm3. Crushed, unscreened limestone has a bulk density of 1.6 to 1.75 g / cm3.

3.2.8

Thermal dissociation of carbonate Thermal dissociation is the most important characteristic of limestone. All carbonate rocks dissociate at high temperatures, forming oxides and CO2 gas. For example: CaCO3 + heat = CaO + CO2 The dissociation temperature of commercially attractive limestone ranges between 896 and 910°C (at a partial CO2 pressure of 100 kPa). The dissociation heat of calcium carbonate is about 3180 kJ/kg of CaO at 25°C. This value is mainly influenced by the purity of the lime and the impurities affecting the quality of the lime. The dissociation temperature varies considerably with the chemical composition.

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The dissociation temperature may be reduced by several hundred degrees due to higher amounts of impurities, such as SiO2, Al2O3, and Fe2O3 in the limestone. The effect of SiO2 (silica) is shown in the following figure.

3.2.9

Fig. 4

p,t diagram of the CaO-SiO2 system (typical)

Curve

Element

Temperature range

1

CaCO3 + SiO2

400–590 °C

2

CaCO3 + 2CaO·SiO2

400–750 °C

3

CaCO3

650–890 °C

Mechanical strength and abrasion resistance Pore volume and pore distribution give the limestone a specific structure, which results in different apparent densities. They have a direct influence on the mechanical properties of the limestone. Mechanical strength and abrasion resistance of the limestone must be sufficiently high to avoid breakage. Breakage of limestone particles during handling or passage through the kiln causes the generation of fine lime and compresses the stone packing in the kiln. The gas flow and heat transfer may thus be adversely affected causing downgrading of the quality of the quicklime (also see Influence of feed size on the retention time in this chapter). The compressive strength varies from 10 MPa for some types of marl and chalk to 200 MPa for some types of marble. INFORMATION The compressive strength of limestone to be burnt in a Maerz lime kiln should generally not be lower than 30 MPa.

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3.2.10

GENERAL INSTRUCTION & OPERATION Technological Principle

Data and properties of limestone The following table lists some fundamental data and properties of limestone. Properties

Data

Expansion coefficient

5 x 10-6 K-1 at 20°C. Total expansion of limestone during heating up from 20 to 800°C is approx. 2-2.5%.

Thermal conductivity

Limestone at 130 °C Dolomitic limestone at 123 °C

1.6341 W / mK 1.4246 W / mK

Integrated specific heat

CaCO3 at 100°C at 800°C CaO at 100°C at 800°C

[kJ / Kg °C] 0.874 1.104

[kcal/kg °C] 0.209 0.264

0.786 0.887

0.188 0.212

Strength

Compressive strength: Shear strength: Tensile strength:

10 – 200 MPa 5 – 20 MPa 2 – 7 MPa

Chemical properties

Limestone and dolomite are unaffected by CO2-free water. Decomposition can only occur at very high temperatures or by reaction with strong acids.

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3.3

GENERAL INSTRUCTION & OPERATION Technological Principle

Calcination of limestone Carbonate rocks decompose at high temperatures releasing gaseous CO2 and convert into calcium oxide and/or magnesium oxide. Depending on the process temperature, a range of products from soft-burnt to hard-burnt lime can be produced. The Maerz lime kiln is designed to primarily produce soft-burnt lime. Therefore, this manual focuses on the production of soft-burnt lime obtained from high-purity limestone. By appropriately adapting kiln design and operating mode, the Maerz lime kiln is also suitable for burning dolomite.

3.3.1

Thermal decomposition of calcium carbonate The thermal decomposition of CaCO3 into CaO and CO2 is an endothermic reaction. CaCO3 + heat = CaO + CO2 It starts at about 810°C with surface calcination and is completed at about 900°C at a partial CO2 pressure of 100 kPa. In order to produce 1 kg of CaO, approximately 3180 kJ of energy are required.

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3.3.2

GENERAL INSTRUCTION & OPERATION Technological Principle

Physical-chemical phenomena during calcination During heating-up, the limestone passes several stages of physical-chemical and thermo-mechanical phenomena. The chemical reaction of calcination starts at the surface of the limestone particle and moves into the core with the progress of reaction. Mechanisms of mass and heat transport take place in parallel during this process. The physical-chemical phenomena may be described, in principle, by the 5 steps represented in the figure below.

Fig. 5

Processes during calcination (typical)

Item

Description

1

Heat transfer by convection and radiation from the surrounding area to the surface of the limestone particle.

2

Heat transfer through the already calcined lime zone.

3

The heat is absorbed by the chemical reaction at the lime-limestone interface on the way into the core. The limestone decomposes into lime and CO2.

4

The generated CO2 diffuses from the centre to the surface of the particle.

5

The CO2 is released from the particle surface into the surrounding atmosphere.

The diameter and density of the particles have a strong influence on the speed for these mechanisms.

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GENERAL INSTRUCTION & OPERATION Technological Principle

With increasing process temperature, the physical properties (especially the volume of the limestone crystals) change through the different stages of calcination. The figure below visualizes these steps by means of a cubical sample.

Fig. 6

Stages of limestone decomposing to lime during calcination (typical)

Item

Description

1 2

When heating up from room temperature to calcining temperature the limestone expands.

3

After surface calcination has begun, the pore volume of the surface zone increases while the volume of the sample remains more or less constant.

4

After calcination is completed, the sample has reached the maximum porosity, but the volume of the sample remains unchanged.

5

When temperature and calcining time are further increased, the lime crystals will start to sinter. The pore volume and the sample volume will decrease.

The strong decrease of the pore and sample volume at high temperatures is caused by crystal growth. Fig. 5 below shows different apparent densities of quicklime which was calcined at different temperatures and over periods ranging from about 3 to 30 hours.

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Fig. 7

Apparent density of quicklime varying with temperature and time, produced from dense, high-calcium limestone (typical)

Item

Description

1

1400°C

2

1300°C

3

1200°C

4

1200°C

5

1000°C

In Fig. 6 below, structures of quicklime with different apparent densities are shown in three scanning electron micrographs.

Fig. 8

Scanning electron micrographs of quicklime (typical)

Item

Density

1

1.5 g / cm

3

2

1.9 g / cm

3

3

2.3 g / cm

3

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3.3.3

GENERAL INSTRUCTION & OPERATION Technological Principle

Reactivity of quicklime The reduction in pore volume notably reduces the specific surface area of the quicklime and causes a strong decrease in reactivity. Quicklime with many pores has a high affinity to water. The reaction with water is exothermal, causing the release of hydration heat, which may be measured as an indicator for the reactivity of quicklime. Other test methods are mentioned in the following figure. The reference values given in Fig. 7 below only apply to the specific limestone examined and may differ from values applicable to different types of limestone.

Fig. 9

Relationship between reactivity testing methods used for quicklime (typical)

Item

Description

1

BS 6463 [°C] after 2 min.

2

EN 459-2 t60 [min] - time to reach 60°C

3

EN 459-2 tu [min] - time for 80% slaking

4

ASTM C110 [°C] - temperature rise after 30 s

5

ASTM C110 [°C] - maximum temperature rise

6

ASTM C110 [min] - time to maximum temperature

7

Acid titration [ml] after 3 min.

8

Acid titration [ml] after 5 min.

9

Acid titration [ml] after 10 min.

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Fig. 10

GENERAL INSTRUCTION & OPERATION Technological Principle

Relationship between reactivity (BS 6463) and apparent density of quicklime (typical)

Due to the influence of the pore volume, the reactivity of quicklime is indirectly proportional to the apparent density. 3.3.4

Influence of feed size on retention time The size of particles fed to the kiln influences the retention time required for the calcining process. Fig. 9 below shows that bigger particle sizes need more retention time in the kiln than smaller ones at a given process temperature. INFORMATION The figure may be used as a guideline for adjusting the burning time to the particle size of the stone.

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Fig. 11

Calcining times for spheres of dense limestone (typical)

Item

Description

1

15 cm

2

12.5 cm

3

10 cm

4

7.5 cm

5

5 cm

6

2.5 cm

GENERAL INSTRUCTION & OPERATION Technological Principle

The influence of particle size and temperature on the calcining and sintering mechanisms leads to the important issue of heat distribution in the kiln. The distribution of open voids in the limestone package must be optimized to allow for uniform gas flow and efficient heat transfer. A lime shaft kiln has to be designed in such a way that the heat is evenly distributed over the whole shaft cross-section. Areas with a high ratio of fine particles can cause heat stagnation, which will result in local overheating. The particles in this area will be overheated, which may lead to an inappropriately high apparent density and possibly even to sintering and/or fusion. The right particle size distribution of the limestone feed, the kiln type, and the kiln operation procedure are closely related, and only an optimized concept will result in optimal quicklime quality.

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GENERAL INSTRUCTION & OPERATION Technological Principle

Summary Heat distribution, temperature, and retention time influence the properties of the produced quicklime. Three categories of particle types may be discharged from the kiln: - not fully calcined - just fully calcined These two categories of particles have a low apparent density and a high reactivity with water. - different grades of calcining/sintering In this case, the particles have an increased apparent density and a reduced reactivity with water. 3.3.5

Lime to limestone factor Calculation based on dry limestone:

CaO  MgO  R2 O3 Lime 100   A Limestone 100  CO2 (1.785  CaO)  (2.092  MgO)  R2 O3 CO2

[%]

Residual CO2 content in burnt lime

CaO

[%]

CaO content in burnt lime

MgO

[%]

MgO content in burnt lime

R2O3

[%]

Impurities in burnt lime

Calculation based on wet limestone:

Lime A  (100 - moisture)  Limestone 100 Moisture [%]

Water content of limestone related to dry limestone

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3.4

GENERAL INSTRUCTION & OPERATION Technological Principle

Fuel Different heating systems burning solid, liquid or gaseous fuels are available for the lime kiln. Quality and type of fuel have a considerable impact on the quality of the quicklime produced. In limestone calcination, fuel is more than just a heat source. The fuel interacts with the process and the combustion products, which in turn react with the quicklime. In the kiln, fuels such as coal, lignite, petcoke, light and heavy fuel oils, low calorific fuels, lean gas, natural gas, as well as combinations of these fuels are used. The selection of the right fuel requires experience and the consideration of numerous parameters. The most important parameters are listed in the following table. Properties

Remarks

Costs

Fuel costs represent 40 to 70% of the production cost.

Calorific value

The calorific value is linked to the costs of fuel per unit.

Moisture

Solid fuels have to be dried to prevent them from sticking together during dosing and transport to the lances.

Sulphur

About 70% of the fuel sulphur is absorbed by the quicklime forming calcium sulphate. The sulphur retained in the quicklime may affect the quality of the product.

Particle size

The particle size of solid fuels influences combustion time and thus production time.

Volatile components

The combustion properties of solid fuels vary with the amount of volatile components and moisture. Consequently, the calorific value and the shape of the flame may change. Volatile components lead to the release of energy, whereas moisture consumes extra energy for vaporization.

Ash

Ash generally contaminates the lime to some degree with silica, alumina, and iron oxide. This may cause the lime lumps to stick together. The pressure on the lime lumps in the charge may enhance this bridging effect. The mixture of ash, lime dust and/or alkali (sodium and potassium) form low-melting mineral stages at the surface of the limestone particles. High amounts of ash may increase the danger of clogging caused by the effects of sintering (bridging) and the formation of low-melting stages.

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3.4.1

GENERAL INSTRUCTION & OPERATION Technological Principle

Definition of calorific values Lower calorific value (LCV) The lower calorific value is the heat available after complete combustion of 1 kg or 1 m3n of fuel and cooling down of the combustion products to start-up temperature. The LCV is defined by excluding the latent heat produced by the condensation of water in the waste gas. Higher calorific value (HHV) This value is the lower calorific value plus the latent heat produced by the condensation of water in the waste gas. Since the water in the waste gas is usually in the steam phase, the vaporization heat cannot be regained. Fuel

3.4.2

Lower calorific value [LCV]

Higher calorific value [HCV]

[MJ/kg] or 3 [MJ/m n]

[kcal/kg] or 3 [kcal/ m n]

[MJ/kg] or 3 [MJ/m n]

[kcal/kg] or 3 [kcal/ m n]

Hard coal, anthracite, coke

28 – 33

6500 – 8400

28 – 35.5

6760 – 8500

Dry wood dust

18

4300

19.3

4600

Fuel oil class S

40.5

9680

43.1

10290

LPG (~30% propane ~70% butane)

92.9

22190

101.2

24181

Natural gas

35.9

8570

39.8

9510

Lean gas

17.9

4275

20.1

4800

Combustion air volume (v’ol) The lime kiln burns fuels using combustion air. The required combustion air volume (see tables under 1.3.5) – considering any excess or deficiency factor – must be entered into the combustion calculation program of the lime kiln.

3.4.3

Wobbe index For gaseous fuels, e.g. coke oven gas, containing tar or other impurities, the installation of an orifice plate to measure the gas flow is required. In order to compensate for varying gas densities, the Wobbe index is added to the formula used for calculating the heat flow. Analogously to the calorific value, the Wobbe index is expressed as W s and W i.

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GENERAL INSTRUCTION & OPERATION Technological Principle

The Wobbe index considers the ratio between the calorific value and the relative density of the gas.

W

3.4.4

H

 Gas /  Air

W

Wobbe index

H

Calorific value

ρGas

Gas density

ρAir

Air density

Heat flow The heat flow is calculated as follows: Heat flow [kJ / h] = gas volume [m3 / h] × Wobbe index [kJ / m3]

3.4.5

Fuel data Solid fuels Fuel

Average composition (% by weight) C

H

O

Vola- Lower tiles calorific value N

H2O

S

Required combustion air v’ol

LCV [%]

[kcal/kg] [MJ/kg] [m3n/Mcal] [m3n/MJ]

Wood

50.4

6.2

43.3

0.1

11

0

75

4300

18.02 1.09

0.2603

Lignite (Rheinbraun)

58.5

4.3

21.0

0.7

11

0.35

46

5278

22.1

0.2606

Bright burning coal

84.0

5.5

8

1.5

11

1.0

35

8100

33.94 1.08

0.258

Hard coal

88.0

5.0

4.5

1.5

11

1.0

25

8350

34.99 1.09

0.2603

Forge coal

90.0

4.5

3.0

1.5

11

1.0

15

8450

35.41 1.09

0.2603

Anthracite

91.5

3.8

2.2

1.5

11

1.0

10

8425

35.30 1.08

0.258

Coke

96.7

0.6

0.6

1.1

11

1.0

0

7870

32.98 1.12

0.2675

Petcoke

89.7

3.6

0.6

0.6

11

5.5

10.7

8240

34.5

0.2627

1.09

1.10

Liquid fuels (Table valid for sulphur contents up to 2.5%) C/H Number

Density

Lower calorific value

Required combustion air

d

LCV

v’ol

[g/cm3]

[kcal/kg]

[MJ/kg]

[m3n/Mcal]

[m3n/MJ]

Fuel oil L (light)

6.7

0.86

10150

43

1.099

0.2625

Fuel oil S (heavy)

7.8

0.96

9680

40.5

1.103

0.2634

6.5

0.843

10052

42

1.096

0.2618

7

0.889

9906

41.5

1.098

0.2623

7.5

0.935

9760

41

1.102

0.2623

8

0.981

9614

40

1.108

0.2646

8.5

1.026

9468

39.6

1.114

0.2661

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GENERAL INSTRUCTION & OPERATION Technological Principle

Gaseous fuels Fuel

Lower calorific value

Average composition (% by volume)

LCV

CO

H2

CH4

CnHm

CO2

Required combustion air N2

O2

HHC* v’ol

[MJ/m3n]

[%]

[m3n/ Mcal]

[m3n/MJ]

Carbon 3021 monoxide CO

12.64

100

0.79

0.1887

Hydrogen H2

2572

10.76

0.93

0.2221

Methane CH4

8556

35.80

1.12

0.2675

Ethane C2H6

15370

64.31

100

1.09

0.2603

Propane C3H8 22363

93.57

100

1.07

0.2556

Butane C4H10

122.51

100

1.06

0.2532

Liquefied petroleum 27366 gas (LPG) ~30% propane ~70% butane

114.5

100

1.06

0.2532

Russian natural gas

8915

37.30

93.3

4.9

1.1

0.8

1.109

0.2649

Groningen natural gas (NL)

7552

31.6

81.4

3.2

0.8

14.1

1.109

0.2649

Blast furnace gas

750–951

3.14–3.98 24–30 1–2

0.8

0.1911

Coke oven gas

4275

17.9

1.027

0.2453

[kcal/m3n]

29280

100 100

8.6

51.4

19–21 56–57 25.9

2.7

8.1

0.3

3.0

HHC* = Heavy Hydrocarbons

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4

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Design and Functioning (Type FS) Mandatory reference material This chapter contains general and typical information. For details, dimensions as well as to determine and locate a specific component, reference to diagrams and drawings is mandatory. The complete reference list is included in the Appendix. Items required with this chapter - 010

“Steel binding - assembly“

- 059

“Poking door with measuring point“

- 154

“Protection tubes for measuring points“

- 178

“Stone distributor“

- 192…195

“Installation of limit switches“

- 500

“Hydraulic scheme” + 502 list of material

- 510

“Firing system: Liquid fuel “ (if applicable)

- 520

“Firing system: Natural gas “ (if applicable)

- 530

“Firing system: Lean gas “ (if applicable)

- 540

“Firing system: Solid fuel“ (if applicable)

- 550

“Compressed air scheme“

- 600

“PI Diagram“

- 603

“Configuration control system“

- 611

“Installation: Electrical equipment“

- 612

“Installation: Measuring equipment“

- 640

“Instrument list“

- 641

“Motor list“

- Electrical documentation / Manufacture’s documentation - Instruction Manual Book-02, Specific Data & Component Description Technical data Important benchmark figures and performance data can also be found in chapter Technical Data at the beginning of this of Book-02.

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4.1

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Design

Fig. 12

Overview

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Item

Description

1

Reversal flap filter / direct chimney

2

Reversal flap combustion air / waste gas

3

Reversible conveyor belt

4

Rotating bucket

5

Shaft closing flap

6

Lance cooling air duct

7

Combustion air duct

8

Kiln door

9

Discharge hopper

10

Lime vibration feeder

11

Discharge flap

12

Cooling air duct

13

Discharge table

14

Crossover channel

15

Suspended cylinder

16

Ring channel

17

Kiln shaft

18

Burner lances

19

Level indicator

20

Stone distributor

21

Stone distributor - swivel-mounted

22

Limestone vibration feeder

23

Kiln hopper

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4.2

Design

4.2.1

Parallel-flow firing system

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

The parallel-flow firing system yields ideal burning conditions. The flame moves in the same direction as the charge, providing the maximum temperature difference at the beginning of calcination in the burning zone. The flame pattern ensures a minimum temperature at the end of the calcination process in order to protect the smaller particles in the charge from over burning. 4.2.2

Preheating the combustion air The regenerative preheating of the combustion air provides a thermodynamic advantage. The stone preheating zone acts as a regenerator for preheating the combustion air produced by the excess heat of the waste gas. The limestone itself temporarily stores the heat. This regenerative process is completely insensitive to dustladen or corroding gases while providing excellent heat transfer characteristics. Regenerative preheating of combustion air makes the kiln virtually independent of the excess combustion air factor. This considerably simplifies setting the correct length of the flame, as a large volume of excess air produces a shorter flame while a smaller volume of excess air produces a longer flame.

4.2.3

Two-shaft kiln The regenerative system and the parallel-flow firing system demand a kiln with two shafts (1 and 2). The two shafts alternate their firing and regenerative functions at intervals. The connecting channel between the shafts is located near the bottom end of the burning zone. At this point, the kiln gases flow from the combustion shaft to the regenerative shaft.

Fig. 13

Top view: definition of shaft number

Item

Description

1

Kiln shaft

2

Combustion air pipe

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4.2.4

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Burner lances Fuel is fed from a main system through a number of steel lances and is evenly distributed over the cross-section of the burning shaft. The lances enter the shafts at the upper, cooler part of the preheating zone and are freely suspended into the vertically descending charge. In addition to housing them, the regenerative shaft also flushes air through the lances to cool and protect them from dust. The amount of fuel entering the lances of the firing shaft is regulated by means of a valve system that ensures even distribution to all lances.

4.2.5

Reversing devices Periodically switching from the burning to the non-burning shaft (regenerative shaft) requires reversing devices for fuel, combustion air, and waste gas. All reversal processes are controlled automatically. The reversal processes are steered automatically. The supply of the combustion air, alternatively the waste gas, is steered by a hydraulic cylinder. Positions of the reversal flap Regenerative shaft (secondary shaft) – waste gas pipe is open Burning shaft (primary shaft) – combustion air pipe is open

Fig. 14

Combustion air / waste gas reversal (typical)

Item

Description

1

Regenerative shaft

2

Burning shaft

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4.2.6

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Charging device The constant and accurate throughput required by a kiln of such great thermal efficiency is provided by the charging and discharging device. With each charging sequence, a scaled quantity of limestone is released into the shaft. This cold stone will absorb the excess heat from the waste gas. The number of charges per hour and the duration of the heating period are adjusted according to the corresponding production parameters. Charging starts with the kiln hopper (1) above the charging platform. From here a vibration feeder (2) serves the limestone onto a reversible conveyor belt (3). The conveyor will now fill one of the rotating buckets (4) alternately. These buckets will charge the kiln shaft, distributing the stone appropriate and evenly via the stone distributor (5). The filling level of the shaft itself is observed and maintained by the signal of the level indicator.

Fig. 15

Charging device (typical)

Item

Description

Item

Description

1

Kiln hopper

4

Rotating bucket

2

Vibration feeder

5

Stone distributor

3

Reversible conveyor belt

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4.2.7

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Discharge device Calcined lime is continuously discharged from the shafts by means of hydraulically operated discharge tables (1). The rate of discharge is automatically controlled by the kiln control system according to the level of stone measured in the preheating zone. The moving discharge tables (1) are located under the cooling zone of each shaft. The tables feed a hopper, located below and collecting the calcined lime discharged during each burning period. The cooling air enters through this receptacle and flows to the shaft via the lime embankments on the discharge tables. Because of the high pressure inside the kiln, the area is sealed off by airtight, hydraulically operated discharge flaps (2). During each reversing period, the discharge flaps will open to allow the lime to drop into a pressure-free discharge hopper (3) equipped with a vibrating feeder (4) for final discharge.

Fig. 16

Discharge device (typical)

Item

Description

Item

Description

1

Discharge table

3

Discharge hopper

2

Discharge flap

4

Vibrating feeder

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4.2.8

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Hydraulic system Most flaps inside the air supply pipes, the reverse flaps, and the charging and discharging devices are all operated hydraulically. A hydraulic system is provided because it can generate great force by means of small components. It is also safe and requires only minimum servicing.

4.2.9

Kiln refractory lining The preheating and cooling zones are lined with abrasion-resistant fire bricks. Due to combustion with preheated air and the high cross-section output, the burning zone must be lined with magnesite. After a certain period of time, a thin crust of dust will cover the lining, which considerably contributes to the protection of the brickwork. Permanent lining consisting of different insulating stones, mats, or plates is arranged behind this chamotte or magnesite lining.

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4.3

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Functional description The Maerz Lime Kiln allows for thermally efficient production of high-quality soft-burnt lime. To reach a high degree of thermal efficiency, the Maerz Lime Kiln is equipped with special features to provide ideal calcination conditions for the production of quick lime. A brief summary of the calcination of limestone with regard to necessary kiln features illustrates the requirements the Maerz Lime Kiln has to meet. For details about limestone calcination, please refer to chapter Basic Technological Principles.

4.3.1

Special requirements of limestone calcination The carbonate in the limestone decomposes under specific thermal and heat flow conditions. - The decomposition or calcination temperature depends upon the partial pressure of carbon dioxide. In order to enable decomposition of the stone, the necessary dissociation heat must penetrate the surface of the stone through an insulating shell of calcined lime. This requires that the stone surface be preheated. Since an enormous amount of this heat may be transmitted into the stone, the admissible heat flow rate is considerably less towards the end of the calcination process. - The kiln charge comprises a range of small and large particle sizes. As smaller particles absorb heat more readily, the admissible heat flow for these particles will drop to the minimum value after a short firing period. Longer particles require a longer period of heat exposure to complete calcination. As the kiln charge moves towards the end of the calcination zone, the calcination process requires less heat.

4.3.2

Process description The two key operating principles are: The stone-laden preheating zone (C) in each shaft acts as a regenerative heat exchanger, while the charge has the function of a heat accumulator. During the first stage, the excess heat produced by the waste gas (8) is transferred to the stone in shaft 2 (3). During the second stage, the heat is transferred from the stone to the combustion air (1). As a result, the combustion air is preheated to about 700°C. The net heat consumption of the kiln lies between 3'500 and 3'700 kJ/kg of quick lime. The calcination of the quick lime is completed at the level of the crossover channel (7) at a moderate temperature of about 1'050 °C. This favourably affects the production of highly reactive quick lime, which can, if required, be produced with a low CaCO 3 content. During the burning period, cooling air (5) flows evenly and continuously into the bottom end of the shafts. Prior to reversal, pressure relief flaps vent both combustion air (1) and cooling air (5) to the outside.

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GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

The figure shows the basic operating principle of the PFR Lime Kiln and illustrates the two operating stages. The two shafts are alternately charged with limestone while lime is discharged continuously from the bottom of the shafts.

Fig. 17

Operating principle

Item

Description

1

Combustion air

2

Burning shaft

3

Regenerative shaft

4

Burner lance

5

Cooling air

6

Heating gas ring channel

7

Crossover channel

8

Waste gas

A

Cooling zone

B

Burning zone

C

Preheating zone

First stage During the first stage, fuel is injected through lances (4) into shaft 1 (2) and burns down in this shaft using combustion air (1). The heat is released and partially absorbed by the calcination of limestone. Through the base of each shaft, cooling air (5) is blown upwards to cool the lime. The cooling air (5) in shaft 1, together with the waste gas (8) and the carbon dioxide from calcination, passes through the interconnecting overflow channels into shaft 2 (3) at about 1'000°C. In shaft 2 (3), the gases from shaft 1 (2) mix with the cooling air (5) blown upwards from the base of the shaft. These gases heat up the stone in the preheating zone (C) of the regenerative shaft (3).

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GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Second stage The second stage will start after 8 to 15 minutes. The fuel and air flow to shaft 1 (2) is stopped, while reversal is initiated. After shaft 1 (2) has been charged with limestone, the same amounts of fuel and combustion air (1) are injected into shaft 2 (3). The waste gas (8), the carbon dioxide produced during calcination, and the cooling air (5) flow upwards through shaft 1 (2) and heat up the charge in the preheating zone (C) of this shaft. Waste gas is vented through the top of shaft 1 (2). Reversal During each reversal cycle, the shaft has first to be de-pressurized. Afterwards, the burnt lime is discharged. Finally, the shaft is charged and re-pressurized. Another possible operating mode is to charge the regenerative shaft while the burning process is still in progress.

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4.4

Characteristic data

4.4.1

Grain size of charged limestone

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

The Maerz Lime Kiln is designed to process different limestone grain sizes. Fine lime kiln type For grain sizes between 15 to 40mm or 40 to 80mm (exceptionally, 10 to 90mm). Standard lime kiln type For grain sizes between 30 to 70mm or 60 to 120mm (exceptionally, 25 to 140mm). INFORMATION For the exact specifications of this particular lime kiln, refer to chapter Technical Data.

4.4.2

Operating cycles The duration of one operating cycle per shaft ranges from 8 to 15 minutes at nominal output. INFORMATION For the exact specifications of this particular lime kiln, refer to chapter Operation.

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4.4.3

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Heat and mass flow

Fig. 18

Heat and mass flow (typical)

The figure above illustrates the heat and mass flow based on 1 kg of quick lime produced inside the Maerz Lime Kiln. (The limestone used for this example is of average quality).

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4.4.4

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Temperature profile

Fig. 19

Typical temperature profile of a Maerz lime kiln as witnessed by a passenger observer.

Item

Description

A

Material flow

B

Gas flow

C

Heat input (fuel)

a

Preheating zone

b

Burning zone

c

Cooling zone

1

Air

2

Waste gas

3

Product

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4.5

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Kiln control system The kiln control system comprises the following main components: - Programmable logic controller PLC with local I/O stations - Data bus system - Visualization system INFORMATION Detailed information can be found in the documents listed under ‘Mandatory reference material’ at the beginning of this chapter. The PLC cabinet is usually housed in the same room as the MCC room above the blower house. To reduce the number and length of cables used, the local I/O stations (ET200S family) have been installed in various positions at the kiln. The data bus system (Simatic Profibus) connects the PLC with the local I/O stations. The visualization system is located inside the control room and runs usually on "Siemens WinCC" or the PCS7 software. INFORMATION For the operation of the visualization system, see chapter Operation.

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4.6

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Electric switchboard INFORMATION The following section provides an overview on the switchboard. Detailed Information can be found in the documents listed under ‘Mandatory reference material’ at the beginning of this chapter.

4.6.1

Main components The electric switchboard is equipped with the following main components: Low-voltage main distribution (LVMD)

Fig. 20

LVMD (typical)

Main switch with phase failure/low-voltage protection relay

Fig. 21

Main switch (typical)

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GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

KWh meter, ammeter, voltmeter in front of power distribution system

Fig. 22

Meters (typical)

Protection devices

Fig. 23

Protection devices (typical)

Motor contactors

Fig. 24

Motor contactors (typical)

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GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Auxiliary relays for each motor exit

Fig. 25

Auxiliary relays (typical)

Emergency process stop switch

Fig. 26

Emergency process stop (typical)

Frequency converters

Fig. 27

Frequency converters (typical)

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4.6.2

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Safety information - Operation and maintenance must be restricted to well-trained and authorized certified electricians. - During normal operation, the door to the MCC room must be closed. - All switch cabinet doors must be closed. - After the electric switchboard has been put into operation, all main switches and the motor protection switch are turned on. - During normal kiln operation, all motors are automatically started and stopped by the kiln control system. - For maintenance purposes, most motors can be controlled from the local control panel installed close to the respective motor. NOTICE While the motors are controlled locally, all safety and process locks are put out of operation. Only the motor protection switch remains in operation. Whenever a motor is switched off for inspection, maintenance or repair purposes, the local isolator must be turned off and secured with a padlock. Make sure there is only one key to this padlock and appoint a person who will be solely responsible for this key. - The conditions 'operating', 'ready-to-operate', and 'electrical malfunction' are reported to the PLC and displayed at the visualization system. - The current power consumption is recorded by the report system.

4.6.3

Additional documents This information can be found in the documents listed under ‘Mandatory reference material’ at the beginning of this chapter.

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4.7

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Local operation panel INFORMATION The following section provides an overview on the electric panel. Detailed Information can be found in the documents listed under ‘Mandatory reference material’ at the beginning of this chapter

4.7.1

Main components In general, all motors should have a local operation panel or electrical disconnector according to the local regulation and the client's/ Maerz standards.

Fig. 28

Local operation panel (typical)

Item

Description

1

Local operation panel for direct started motor - STOP pushbutton (red) - START pushbutton (black) - selector switch (AUTO / 0 / LOCAL)

2

Local operation panel for VVVF-controlled motor - STOP pushbutton (red) - START pushbutton (black) - selector switch (AUTO / 0 / LOCAL) - speed switch (INCREASE / 0/ DECREASE)

3

Local operation panel for skip motor - STOP pushbutton (red) - START pushbutton (black) - selector switch (AUTO / 0 / LOCAL) - speed switch (INCREASE / 0/ DECREASE) - UP pushbutton (black) - DOWN pushbutton (black) - RESET pushbutton

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4

Local operation panel for process stop - STOP pushbutton (red)

5

Local operation panel for discharge table - illuminated pushbutton

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

NOTE All stop pushbuttons are mechanically locking and must be released by authorized operating personnel.

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4.8

Instrumentation

4.8.1

General description

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

The lime kiln is equipped with different instruments for the following purposes: - Process visualization and monitoring - Automatic and remote control operation - Recording current and historical process data - Recording process data for protocols Detailed Information can be found in the documents listed under ‘Mandatory reference material’ at the beginning of this chapter. 4.8.2

Arrangement of instruments This information can be found in the documents listed under ‘Mandatory reference material’ at the beginning of this chapter.

4.8.3

Wiring diagrams This information can be found in the documents listed under ‘Mandatory reference material’ at the beginning of this chapter.

4.8.4

Purpose of the most important measuring instruments

Name

Description

Optical pyrometer (channel temperature)

The optical pyrometer is installed at the connecting channel and can be used to estimate the exact length of the flame in the burning zone. This is the most important instrument used in combination with the kiln. Measuring range is 600 to 1'200 °C. Limit values are set at the visualization system. If a process value exceeds the limits, fuel feed is automatically interrupted and an alarm is triggered. The optical pyrometer measures the temperature on the refractory lining surface.

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GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Name

Description

Thermocouples (kiln temperature)

In addition to the optical pyrometer, the kiln channel is also equipped with thermocouples. Since the channel temperature represents the most important process value, the thermocouples are used to back up readings of the pyrometer. Measuring range is 0 to 1'200 °C, and limits are also set at the visualization system. If a process value exceeds the limits, fuel feed is automatically interrupted and an alarm is triggered. Please note that the reaction time of the thermocouples is longer than that of the optical pyrometer and that they may, therefore, not be used to determine flame length. On the other hand, the optical pyrometer is not capable of measuring the temperature as precisely as the thermocouples. The thermocouples measure the temperature of the hot gas flowing through the connecting channel.

Resistance thermometers (lime discharge temperature)

Resistance thermometers have been installed above the discharge tables of each shaft. Limits are set at the visualization system. If a process value exceeds the set values, an alarm will be triggered. However, kiln operation can continue. The instruments measure the lime discharge temperature and are influenced by cooling air. In this case, the current temperature of the lime is higher than the process temperature. The difference can be verified by shutting down the kiln for 20 minutes.

Resistance thermometers (waste gas temperature)

Resistance thermometers measure the waste gas temperature directly behind the combustion air relief flaps and in front of the filter inlet. Limits are set at the visualization system. If a process value exceeds the set values, an alarm will be triggered. However, kiln operation can continue. To prevent the filter from overheating the automatic control system is programmed to perform two steps. During the first step, the quench air flap opens and fresh air is mixed with waste gas reduce the temperature. Should the waste gas temperature still be too high, the waste gas is derived directly to the chimney, and the kiln is stopped.

INFORMATION The waste gas temperature varies with kiln reversals.

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GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Name

Description

Thermocouples (temperature at the lance tips (Option))

Thermocouples are installed in each shaft at lance tip level. Limits are set at the visualization system. If a process value exceeds a set value, an alarm will be triggered. However, kiln operation can continue. The measured temperatures are an indication of how much the lances have burnt down.

Thermometer (combustion air temperature)

The combustion air temperature is measured inside the main supply pipe. The measured value is used to convert the air volume to normal conditions.

Resistance thermometer (hydraulic oil temperature)

The hydraulic oil temperature is measured inside the oil tank of the hydraulic unit by means of a resistance thermometer. The kiln control system reads the value and controls the heating and cooling of the hydraulic oil. If the temperature rises too high, an alarm is triggered, and the hydraulic pumps are shut down for safety reasons.

Thermometer (gas temperature)

The gas temperature is measured in the main gas supply pipe and is used by the kiln control system to convert the gas volume to normal conditions.

Pressure gauge (gas pressure)

The gas pressure is measured in the main gas supply pipe and is used by the kiln control system to convert the gas volume to normal conditions. If values are higher or lower than set limits, the kiln is automatically shut down.

Flow meter (gas flow)

The gas flow is measured in the main gas supply pipe and is used by the kiln control system to convert the gas volume to normal conditions. If values are higher or lower than set limits, the kiln is automatically shut down.

Room thermometer The temperature inside the blower house is measured with a room (blower house temperature) thermometer having a measuring range of -30 to +60 °C. The measured value is required for calculating the air to be supplied by the blowers.

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GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Name

Description

Pressure gauge (kiln, combustion, and cooling air pressure)

The combustion and cooling air pressures are measured in the main supply pipes leading to the kiln. The kiln pressure is measured inside the connecting channel. Limits are set at the visualization system. If values are higher or lower than set limits, the kiln is automatically shut down, and an alarm is triggered. The minimum pressure must be 30 mbar below the current operating pressure used to achieve the kiln production rate. The operating pressure varies with the kiln production rate and the grain size of the limestone used. The upper limit must be 50 mbar above the normal operating pressure.

Pressure gauge The pressure of the lance cooling air is measured in the pipes (lance cooling air pressure) leading to the kiln. The limits are set at the visualization system. If values are higher or lower than set limits, the kiln is automatically shut down, and an alarm is triggered. Pressure gauge (compressed air pressure)

The compressed air pressure is measured in the main air supply pipe. Limits are set at the visualization system. If values are higher or lower than set limits, an alarm will be triggered. The kiln is automatically shut down due to a lack of compressed air.

Slope switch (lime level in discharge hoppers, overload message)

To prevent the lime discharge hoppers from overfilling, transversal slope switches have been installed to monitor the maximum level.

Flame detector (presence of flame)

The flame detector (UV sensor) monitors the flame of the start-up burner while the kiln is being preheated.

If a switch engages, an alarm is triggered, and the kiln is shut down automatically.

If no flame is detected, the flame detector automatically closes the gas valve and triggers an alarm. The kiln must be re-started after flushing. Level indicator (stone level measuring)

On top of each shaft a mechanical measuring device is installed, which register the filling level. Detailed information can be found in the specific chapter.

Ultrasound meter (combustion air flow)

The combustion air flow is measured by means of an ultrasound meter. The kiln control system uses the actual and nominal air flow to adjust the air factor of the fuel burnt in the kiln. If the excess air flow is too low, fuel feed is stopped automatically.

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Name

GENERAL INSTRUCTION & OPERATION Design and Functioning (Type FS)

Description

Weighing cell The kiln charging hopper scale is mounted on multiple weighing cells (kiln charging hopper scale) (load cells). These weighing cells are connected to a measuring amplifier. The empty weight of the hopper (tare) is set to 0 kg at the measuring amplifier. The weighing unit is set to maximum capacity according to the size of the kiln. The analog output signal of the measuring amplifier is used by the kiln control system to regulate the charging system.

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5

GENERAL INSTRUCTION & OPERATION Commissioning

Commissioning Mandatory reference material This chapter contains general and typical information. For details, dimensions as well as to determine and locate a specific component, reference to diagrams and drawings is mandatory. The complete reference list is included in the Appendix. Items required with this chapter - 056

“Expansion joint sheet“

- 057

“Rupture sheet“

- 580

“Lubricating chart “

Technical data Important benchmark figures and performance data can also be found in chapter Technical Data at the beginning of this of Book-02.

5.1

General information / Definition The customer is responsible for the installation of the delivered equipment, if the installation is not in Maerz scope of supply. The installation has to be done according to Maerz engineering documents and instructions and in good workmanship with professional personnel. It is the customer's responsibility to ensure the quality of the installation. Maerz can be ordered to supervise the installation work. Maerz incorporated the manufacturer's technical information and instruction into Maerz engineering of the equipment within Maerz scope of supply. The operator can then use the plant in accordance with the instructions in the instruction manual. Local regulations possibly need to be complied with and corresponding tests run. INFORMATION The "requirements for cold commissioning" are in the site manager's responsibility. They correspond to the end of the construction work. Commissioning is divided as follows: - Cold commissioning - Testing of the single components and the sub-systems - Hot commissioning - Ignition and start-up of the kiln - Conversion to lance firing - Stabilisation of the process - Conclusion and handing over of the plant of the operator.

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5.2

Requirements for cold commissioning

5.2.1

Consumables

GENERAL INSTRUCTION & OPERATION Commissioning

Available in the required quality and quantity, including reserves In the interests of continuous charging, limestone must be available in sufficient quantities. Sufficient fine material must also be available in order to protect the refractory brick lining of the kiln upon initial charging against damage Fuel for all the installed firing systems Fuel for the start-up system Electrical power supply, (grid stability under load?) - Emergency power supply tested (where applicable) (battery loaded, diesel tank full, start as specified...) Compressed air Inert gas Additional fuels available, for example: Steam (where applicable) Water for gas booster (where applicable) 5.2.2

Lubricating points All lubricating points have to be lubricated in accordance with the instructions.

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5.2.3

GENERAL INSTRUCTION & OPERATION Commissioning

Shaft construction The mechanical equipment must be complete mounted Unscrew the bursting plate's needle-screw before the pressure test is performed. Test for leakage in the kiln WARNING Risk of injuries! Machines and drives may start automatically. Keep a sufficient distance from all moving parts. Switch off the machines and secure against restarting. WARNING Risk of squeezing! There is a risk of being squeezed when working at the machine or its components. Be particularly careful under these circumstances! Part one: - Set the reversal flap combustion air / waste gas in the vertical position, (see graph 1). - Close the relief valve (combustion air) and switch on the combustion air blower briefly, on the minimum rotational speed. - Check the tightness through the manhole at the reversal flap.

Fig. 29

Vertical position of the reversal flap / waste gas

Item

Description

Item

Description

A

Combustion air

C

Waste gas

B

Reversal flap

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GENERAL INSTRUCTION & OPERATION Commissioning

Part two: - Set the reversal flap combustion air / waste gas in the horizontal position (see figure 2). - Close the relief valve (combustion air) - Pressurise the kiln using variable combustion blowers or cooling air blowers - Check the tightness through the manhole at the filter / direct chimney - The reversal flap must be completely tight in both positions, (vertical / horizontal).

Fig. 30

Horizontal position reversal flap / waste gas

Item

Description

Item

Description

A

Combustion air

C

Waste gas

B

Reversal flap

Kiln Pressure Test (Leakage Test) - Pressurize the kiln using a variable air blower. - Test conditions for empty kiln (without stone filling): p Start 350 mbar + duration 10 min = p End at least 250 mbar - Check for leakage: Entire kiln steel body and air system - If required release pressure and repair the leakages - Repeat, until the loss is within acceptable range - Rupture sheet (drawing 057): At 400 mbar pressure, screw the needlebolt to 5 mm clearance and counter lock Only with kiln pressure test successfully completed the welding and the kiln erection as such is completed. A test protocol shall be established to release the erecting contractor.

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GENERAL INSTRUCTION & OPERATION Commissioning

If need be, test the fuel system, (including the start-up burners), all the respective valves and instruments; including a pressure test in accordance with the relevant regulations. Start-up burner and flame monitor ready for operation 5.2.4

Refractory Refractory lining complete Dried out, where necessary (see erection instructions)

5.2.5

Kiln systems Hydraulic pipings have been purged, the hydraulic system has been checked and is ready for operation. All blowers (combustion air and cooling air) have been checked and are ready for operation. Compressed air pipings have been purged, the compressed air system has been checked and is ready for operation. The limestone feeding system and the lime discharge system have been checked and are ready for operation. All kiln flaps have been checked and are ready for operation. The start-up burner must be connected, checked and ready for operation. All drive units have been checked and are ready for operation. All pipes, valves and flaps have been checked for leaks, cleanliness and proper functioning, and are ready for operation.

5.2.6

Electrical installations / instrumentation All limit switches have been checked and are ready for operation. All drive units have been checked and are ready for operation. All wirings are complete and tested All sensors and signals are adjusted and ready for operation All the instruments installed and connected

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5.2.7

GENERAL INSTRUCTION & OPERATION Commissioning

Firing system The fuel systems are certified and ready for operation The fuel pipes have been checked for leaks, cleanliness and proper functioning, and are ready for operation (report). The gas rack has been checked and is ready for operation (where applicable). The trace heating has been checked and is ready for operation (where applicable). The official operating is approved

5.2.8

Waste gas filter The waste gas filter has been Installed, tested and is ready for operation The cleaning system has been tested and is ready for operation The control system has been tested and is ready for operation

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5.3

GENERAL INSTRUCTION & OPERATION Commissioning

Cold commissioning The components are now switched on and tested.

5.3.1

Suspended cylinder (if existent) All emergency power supply systems as well as all cooling systems and emergency cooling systems for the suspended cylinders must be checked and ready for operation. The suspended cylinder has passed the pressure and flow test and is ready for operation.

5.3.2

Components Setting the flap speed I/O test of the master control system (Signal test from the transmitter to the HMI) Master control system = HMI (level 2 & PLC) I/O test of the sub control system (The entire switching circuit, signal transmitter to the local PLC) Testing the direction of rotation of the electric motors Testing the settings of the frequency converter Setting the sensors (limit switch, load cells, stone level indicators,...) Test blowers, all flaps and associated instruments

5.3.3

Software Provision and configuration of the server systems

5.3.4

Integration test Objective: To test the interaction of all the hardware and software Software test in start-up and production modes Caution: actuators are now set in motion.

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5.3.5

GENERAL INSTRUCTION & OPERATION Commissioning

Charging the kiln with limestone: The first 3 meters are filled with a small fraction, from ~20 – 40 mm (to protect the discharge table) To avoid blockage, the discharge table must be moved hourly Ensure that the expansion joint and the topmost section of the lining are filled with insulating material and that the expansion joint sheet (drawing 056) has been installed. NOTICE Thermal expansion of the brick lining When heated up, the brick lining expands. If the expansion joint is not filled with insulating material, limestone may enter and obstruct the expansion. Stop charging approximately 1 meter below the lances: - Check the supply of cooling air to each lance - Check the transport air supply of the individual lances (if installed) - Check the gas flow of the individual lances (if installed) - Check the alignment of the lances and adjust if necessary

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5.4

GENERAL INSTRUCTION & OPERATION Commissioning

Hot commissioning - Heat up with start-up burners, in accordance with the start-up curve see the chapter "operation" NOTICE The (moist) waste gas is not to pass through the filter. It must flow directly through the exhaust stack. - Change over to lance firing and fuel according to the heating curve see the chapter "operation" INFORMATION Inertia when start-up After changing over to lance firing, part of the supplied heat is initially not supplied to the process, but goes for example to the brickwork instead. This phase stabilises after about 5 days. Only now can one begin with the process adjustments. - Changeover from waste gas stream to normal filter operation once a waste gas temperature of at least 110°C has been reached. INFORMATION Process inertia Changing the kiln parameters and its impact can only be finally assessed after 1 to 2 days.

5.4.1

Process adjustments The kiln should reach the output requested by the customer under the given local conditions. - After about 5 days, the first sellable lime will be produced. - Increasing the kiln capacity to the nominal production capacity will take approximately another 4 days. - The guarantee test run, as per the contract, can begin once the adjustments have been successful.

5.5

Conclusion of the commissioning Compilation and handing over of the commissioning documentation The plant is handed over to the customer

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6

Operation

6.1

General

GENERAL INSTRUCTION & OPERATION Operation

The following sections provide general information on how to operate the plant in order to ensure optimum performance and trouble-free operation of the kiln. INFORMATION For detailed descriptions of each individual component, refer to: Book-02, Specific Data & Component Description. If a malfunction cannot be resolved by performing the steps described below, notify the manufacturer immediately.

6.2

Safety INFORMATION For detailed safety information, refer to chapter Safety. WARNING Risk of injury! Improper operation may cause damage to persons and/or property. The kiln must only be operated by authorized and trained personnel following the safety instructions. The kiln must only be operated by persons meeting the following conditions: - at least 18 years old - trained to operate the kiln - certified for kiln operation - authorized in writing by the kiln attendant or the person in charge to operate the kiln.

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In addition, when performing operations that require manual intervention, please observe the following: CAUTION High temperatures! During kiln operation, high temperatures are prevailing inside the kiln and on many of its components. Do not touch any hot kiln components until they have cooled down to ambient temperature. Wear Personal Protective Equipment (PPE): Tight fitting work clothing with minimal tear strength, no wide sleeves, no rings nor other jewelry, etc. Safety goggles to protect the eyes against liquids and parts flying about Dust mask to protect of inhaling particles or emissions. Face screen to protect the eyes and the face against flames, sparks, or embers as well as hot particles or emissions. Safety shoes to protect against heavy parts being dropped, and slipping on slippery surfaces Safety gloves to protect the skin against friction, excoriation, pricking and deeper injuries on the hands and against contact with health affecting substances. Safety hat to protect against objects and materials falling down or flying around Ear defenders to protect against hearing damage

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The kiln works with overpressure (max. 400 mbar). WARNING The kiln is operated with overpressure. Flames or hot gases may spurt out when the kiln doors are opened. Overpressure may cause the kiln doors to fly open with great force. Do not open the kiln doors until the pressure difference between the inside and the outside of the kiln is zero. The plant works with CaO. CAUTION Risk of chemical burns caused by CaO! There is a risk of sustaining chemical burns in places labeled accordingly. Any person working inside these rooms must proceed with great caution when handling caustic materials. In addition to the danger of damages to clothing, there is also a risk of burning eyes, skin, and possibly mucous membranes. Burning one’s eyes may cause irreparable visual impairment. When handling caustic materials, personal safety equipment is to be worn as required by the Chemical Safety Datasheet. The plant operator must at all times keep rinsing liquids available for eye cleaning. WARNING Danger of life! Entering the kiln area involves considerable risk. Access to the kiln area is limited to persons informed of dangers and instructed about the appropriate behavior inside the kiln area. These persons must also be authorized by the plant operator to access the kiln area. WARNING Danger of life caused by CO and CO2! During calcination, CO2 and CO are produced. The calcination process continues after the kiln has been shut down. The inhalation of CO2 and CO can lead to poisoning, damage to the respiratory system and death.

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GENERAL INSTRUCTION & OPERATION Operation

When inside the kiln area during kiln operation make sure: - to notify the kiln attendant prior to entering the kiln area - not to enter secured danger zones Prior to performing any work inside the kiln area, make sure: - to notify the kiln attendant - to shut down the kiln and secure it against re-starting Prior to beginning working at the kiln, also secure any kiln components to be operated against re-starting, e.g. by pushing the emergency stop button, disconnecting safety fuses or switching off and locking the main switch. Record the time and reason for shutdown, as well as the name of the staff working inside the kiln area, and the time of re-starting in the operating person’s log. Prior to restarting the kiln, have staff members sign off as they leave the kiln area (see example).

Fig. 31

Time

Date

Example of an Operator’s log entry: Incident (failure, reason for shutdown, re-start, etc.)

Name of the staff member working inside the kiln area

Signature of the staff member having left Time of leaving the the kiln area and kiln area prior to re-starting the kiln

Example of an Operator’s log entry

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6.3

GENERAL INSTRUCTION & OPERATION Operation

Visualization system The kiln is remote controlled and operated via the visualization system. However, manual control during normal operation is possible as well.

Fig. 32

Screen (typical)

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6.3.1

GENERAL INSTRUCTION & OPERATION Operation

Screen layout The screen is composed of two areas: - Overview area - Working area

Item

Description

1

Overview area Area with general information and operating functions. This area does not change in comparison with the working area.

2

Working area Area with specific pictures, tables, and messages for kiln operation, troubleshooting, and maintenance. Schematic display of plant areas and their components. (process picture). Buttons can be used to call up additional process pictures. Each process picture contains the current parameters. The settings can be changed.

Overview area Item

Description

1.1

Picture buttons See detailed description

1.2

Alarm rows Show the last two alarm messages.

1.3

Alarm acknowledge Alarm acknowledge button

1.4

Burning time counter Shows the actually remaining burning time.

1.5

Date / Time Shows current date and time. Operator level Shows current operator level.

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1.6

GENERAL INSTRUCTION & OPERATION Operation

General buttons Use the buttons to access different pop-up menus.

Function Pop-up picture: Login Opens the login window necessary to log into the system as OPERATOR, ENGINEER, or ADMINISTRATOR. The corresponding passwords are defined during the initial operation of the kiln. See detailed description Example of pop-up picture: Language selection To choose between English and the customer's language. Controlling user level: Operator

Print Screen To print out the current screen.

Acknowledge horn Turns off the signal horn for the current alarm message without acknowledging. Controlling user level: Operator

Windows Explorer Switches off WinCC Runtime, so that work can be carried out in the file system of the computer. Not necessary during normal operation. Controlled user level: Engineering

Shutdown Closes the visual display application and shuts down the computer. Controlling user level: Operator

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NOTICE A computer running the visualization system must be switched ON for monitoring the process during normal operation. Working area In addition to the pictures shown, pop-up menus are available for some items. Use the pop-up menus to further adjust settings. If a pop-up menu is available, the mouse pointer will turn green when the mouse is moved over the corresponding item. The working area includes the following operating elements. Element

Function Picture button To change the process pictures directly from the working area. This is the same function as via picture buttons. Operation/selection button and status display To switch a plant function ON/OFF. To select different plant functions. Including the status indication of the button. Kiln operation Kiln mode Air cannons Flame control Burning timer etc.

Example of pop-up picture:

ON/OFF button To switch a device of the plant ON/OFF. Motor start / stop Valve open / close etc.

Example of pop-up picture:

Selection buttons Example of pop-up picture: To select one or more subassemblies from a list of buttons. Selection of a replacement motor Loading options etc.

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Element

GENERAL INSTRUCTION & OPERATION Operation

Function Check box For the selection of an individual subassembly from a list Hydraulic pumps etc.

Example of pop-up picture:

WARNING Risk of injury from running motors! Running the motors using the pop-up menus is only allowed during manual operation and when the kiln has been shut down or is being pre-heated. Running motors may cause personal injury or death. Before you turn on the motors, make sure nobody is in danger.

6.3.2

Color definitions

Element

Function Picture button Overview area: Grey for passive Light green for active Working area: Grey with shadows for OUT/IN position

Example:

Output field Display of current value White background Black writing Output field Display of nominal value White background Green writing Input field Display of set value Green background White writing System motor Display of motor status Grey for STOP Purple for ISOLATED Yellow for PRE SELECTED Light green for RUNNING Red flashing for ALARM

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Element

GENERAL INSTRUCTION & OPERATION Operation

Function System valve Display of valve status Grey for CLOSED Yellow for PRE-SELECTED Light green for OPEN Red flashing for ALARM

Example:

System pipe Display of pipe status Grey for NO FLOW Green for hydraulic FLOW Yellow for gas FLOW Blue for air FLOW Brown for coal/wood/oil FLOW Tag Display of the flag status White for NORMAL Flashing red light for ALARM

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6.3.3

GENERAL INSTRUCTION & OPERATION Operation

User level All users of the visualization system must log into the system. Different login levels keep the system safe from unauthorized operation and modifications. The login levels are separated into three different categories: - OPERATOR Ordinary user not authorized to change all kiln parameters - ENGINEERING Superior user authorized to change all kiln parameters - ADMINISTRATOR Only for special staff The following table provides a general overview of the user rights assigned to the different login levels: OPERATOR

ENGINEERING

ADMINISTRATOR

Changing process parameters

Yes

Yes

Yes

Changing special parameters

Yes

Yes

Yes

Changing alarm settings

Yes

Yes

Yes

Changing parameters of controller settings

No

Yes

Yes

Modifying the visual display system

No

No

Yes

These rights can be changed if required. NOTICE It is the responsibility of the kiln operator to decide which rights to assign to which person. Passwords must be handled with care and kept safe from unauthorized access. Passwords must not be passed on to unauthorized persons. The manufacturer cannot assume any liability for damage caused by unauthorized or improper operation due to a wrongful assignment of rights.

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6.3.5

GENERAL INSTRUCTION & OPERATION Operation

Parameter tables All of the parameters entered by the operator are used in the PLC system as the basis for the calculation of process setpoints. The calculated process setpoints such as: - Fuel quantity per cycle - Fuel flow - Combustion air flow - Cooling air flow are fed to the governors / control loops. The computational procedure is described in the chapter Operation Calculation of the Process Parameters. Process parameters

Fig. 33

Parameter table “Process parameter” (typical)

Use this screen to change the process parameters of the kiln.

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Special parameters

Fig. 34

Parameter table “Special parameters, screen 1” (typical)

Use this screen to adjust additional parameters for other kiln components.

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GENERAL INSTRUCTION & OPERATION Operation

Discharge parameters

Fig. 35

Parameter table “Discharge parameters” (typical)

Use this screen to adjust discharge parameters, settings and alarms.

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6.3.6

GENERAL INSTRUCTION & OPERATION Operation

Process pictures Kiln

Fig. 36

Process picture "Kiln" (typical)

This plant diagram provides a general overview of the kiln and its components, such as the hydraulic system, cooling air and combustion air blowers as well as suspended cylinders (optional), including their most important operating parameters. The graphical user interface consists of dynamic (active) areas. When the mouse pointer is moved over these areas, a button or check box is opened with a left mouse click. On this page, the process parameters of the kiln can be adjusted and individual components can be started and controlled. All individual systems can be started and controlled from the left-hand side of the graphical interface. Hydraulic unit Each pump can be started individually. A second one might be preselected to support the operation of the hydraulic flap system. The oil temperature is controlled automatically by means of special parameters. Combustion and cooling air blowers When set to automatic mode, the kiln and the blowers are started automatically.

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GENERAL INSTRUCTION & OPERATION Operation

When set to manual mode, each blower can be stopped individually. The lance cooling air blowers only run in manual mode and cannot be switched to automatic mode. Suspended cylinders (option) The kiln monitoring device must adjust the cooling air volumes for the suspended cylinders in such a way that the temperature of the escaping cooling air remains within the stipulated range. Kiln charging Kiln charging via conveyor-reversal belts can be run in automatic mode. The amount and direction of kiln charging is determined by the kiln parameters. WARNING Injury from contusions! Running the drives on the kiln valves using the pop-up menus is only allowed during manual operation and when the kiln has been shut down or is being pre-heated. Moving the kiln valves may cause squeezing or personal injury. Before adjusting the kiln valves, it has to be ensured that nobody is nearby. Hot gases from the kiln can cause burns. Toxic gases from the kiln can cause poisoning.

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GENERAL INSTRUCTION & OPERATION Operation

Firing system: Natural gas

Fig. 37

Process picture "Gas firing system" (typical)

This diagram explains the natural gas firing system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. INFORMATION For further information, refer to the chapter Firing system: natural gas

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GENERAL INSTRUCTION & OPERATION Operation

Firing system: Lean gas

Fig. 38

Process picture "Firing system: Lean gas" (typical)

This diagram explains the lean gas firing system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. INFORMATION For further information, refer to the chapter Firing system: Lean gas

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GENERAL INSTRUCTION & OPERATION Operation

Firing system: Lean gas (Gas booster)

Fig. 39

Process picture "Gas booster" (typical)

This diagram explains the gas booster system for the lean gas system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. INFORMATION For further information, refer to the chapter Firing system: Lean gas

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GENERAL INSTRUCTION & OPERATION Operation

Firing system: Lean gas (Wobbe meter)

Fig. 40

Process picture "Wobbe meter" (typical)

This diagram explains the wobbe meter system for the lean gas system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. INFORMATION For further information, refer to the chapter Firing system: Lean gas

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GENERAL INSTRUCTION & OPERATION Operation

Firing system: Solid fuel (classic)

Fig. 41

Process picture "Firing system: Solid fuel (classic)" (typical)

This diagram explains the solid fuel (classic) firing system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. INFORMATION For further information, refer to the chapter Firing system: Solid fuel (classic).

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GENERAL INSTRUCTION & OPERATION Operation

Firing system: Solid fuel (static)

Fig. 42

Process picture "Firing system: Solid fuel (static)" (typical)

This diagram explains the solid fuel (static) firing system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. INFORMATION For further information, refer to the chapter Firing system: solid fuel (static)

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Fig. 43

GENERAL INSTRUCTION & OPERATION Operation

Process picture " Firing system: solid fuel (static) " (typical)

This diagram explains the classic coal / wood dust firing dosing system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box.

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GENERAL INSTRUCTION & OPERATION Operation

Firing system: Liquid fuel

Fig. 44

Process picture " Firing system: Liquid fuel " (typical)

This diagram explains the liquid fuel firing supply system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. INFORMATION For further information, refer to the chapter Firing system: Liquid fuel

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Fig. 45

GENERAL INSTRUCTION & OPERATION Operation

Process picture " Firing system: Liquid fuel " (typical)

This diagram explains the liquid fuel firing dosing system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. INFORMATION For further information, refer to the chapter Firing system: Liquid fuel

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GENERAL INSTRUCTION & OPERATION Operation

Waste gas filter

Fig. 46

Process picture “Waste gas filter” (typical)

This diagram explains the waste gas filter. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. The kiln works with two modes of operation: - Charging during the reversal time - Charging during the burning time If the kiln is also charged during the reversal time, the filter is operated at a constant negative pressure. If the kiln is charged during the burning time, the negative pressure level is automatically increased in order to ensure that no toxic gases enter the kiln house during charging. Once charging has been completed, the negative pressure level is again reduced to the original value. The filter can be operated both in automatic mode and in manual mode. INFORMATION For further information, refer to the chapter Waste gas filter.

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GENERAL INSTRUCTION & OPERATION Operation

Kiln temperatures (optional)

Fig. 47

Process picture “Kiln temperatures” (typical)

This diagram explains the kiln temperatures (supended cylinder temperatures, discharge table temperatures, centre cone temperatures).

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GENERAL INSTRUCTION & OPERATION Operation

Limestone transport system (optional)

Fig. 48

Process picture “Limestone transport system” (typical)

This diagram explains the limestone transport system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box.

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GENERAL INSTRUCTION & OPERATION Operation

Lime transport system (optional)

Fig. 49

Process picture “Lime transport system” (typical)

This diagram explains the lime transport system. The graphical user interface is composed of dynamic areas. When moving the mouse pointer over these areas, clicking the left mouse button will open a switch or check box. Lime transport progresses in automatic mode (time controlled) or in manual mode, if required.

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6.3.7

GENERAL INSTRUCTION & OPERATION Operation

Alarms Alarms are classified into 3 groups: - Kiln alarms (red background) - Lime discharge (green background) - Limestone alarms (orange background) Depending on the type of alarm, automatic sequencing is either stopped, or merely an alarm will be triggered. In any event, the kiln attendant must localize and solve the problem before acknowledging the alarm and continuing kiln operation either automatically or manually. INFORMATION The Software Documentation contains a list of all possible alarms. Kiln alarms

Fig. 50

Parameter table “Kiln alarms” (typical)

Use this screen to set the limits for kiln alarms.

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GENERAL INSTRUCTION & OPERATION Operation

Fuel alarms

Fig. 51

Parameter table “Fuel alarms” (typical)

Use this screen to set the limits for fuel alarms.

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GENERAL INSTRUCTION & OPERATION Operation

Gas booster alarms

Fig. 52

Parameter table “Gas booster alarms” (typical)

Use this screen to set the limits for gas booster alarms.

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GENERAL INSTRUCTION & OPERATION Operation

Alarm screen

Fig. 53

Alarm screen (typical)

This page shows all active alarms to be checked and processed. The alarm archive lists and stores all alarms that have already been acknowledged. NOTICE Danger caused by unjustified acknowledgment. Take alarm messages seriously at all times. They may highlight dangerous situations. Never acknowledge an alarm message without having removed its cause. The manufacturer cannot assume any liability for damage or processing errors caused by failure to acknowledge alarm messages.

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6.3.8

GENERAL INSTRUCTION & OPERATION Operation

Tuning screens

Fig. 54

Parameter table “Tuning screens” (typical)

Use this screen to adjust the controller parameters Tuning screens are provided for: - Fuel controller - Filter pressure controller - Filter temperature controller - Stone level, SH 1+2 - Lance cooling air controller (optional) - Centre cooling air controller (optional) - Coal dust transport air controller (optional)

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6.3.9

GENERAL INSTRUCTION & OPERATION Operation

Trend messages

Fig. 55

Trend messages (typical)

The trend messages provide an overview as well as a graphical illustration of individual process values. Trend messages are provided for: - Kiln temperature - Kiln pressures - Waste gas filter - Stone level, SH 1+2 - Air volume - Lime temperatures - Fuel system - Kiln parameters - Suspended cylinder temperature (optional)

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GENERAL INSTRUCTION & OPERATION Operation

6.4

Theoretical Basis of Lime Kiln Operation

6.4.1

Modes of operation There follows a graphical representation and a description of the processes that occur in the various modes of operation. The following descriptions always refer to a kiln cycle that runs from left to right. The plant operator must select the respective operating mode in accordance with the following requirements.

6.4.2

Filling mode This mode of operation is used to fill the kiln. Time in minutes

1

2

3

4

5

6

7

8

9

10

Cycle time Burning time (no fuel) Reversal time Charging burning shaft Charging regenerative shaft Lime discharge (shaft 1 + 2) Filling the rotating bucket (shaft 1 +2)

S1

S2

To select this operating mode: - Select CHARGING DURING THE REVERSAL TIME - CHARGING on - Start KILN

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6.4.3

GENERAL INSTRUCTION & OPERATION Operation

Heating mode This operating mode is used to heat up the kiln. Time in minutes

2

4

6

8 10 12 14 16 18 20 22 24 26 28

Cycle time Fuel dosing time start-up burner Reversal time Charging regenerative shaft (RS) Lime discharge (shaft 1 + 2) Filling the rotating bucket (burning shaft BS)

BS

To select this operating mode: - Select HEAT UP - COMBUSTION AIR BLOWER on - FLAME DETECTOR on - CHARGING on - DISCHARGE on 6.4.4

Production mode “charging during reversal time” This mode of operation is selected for continuous operation. Time in minutes

1

2

3

4

5

6

7

8

9

10 11 12 13 14

Cycle time Burning time Fuel dosing time Burn-out time Reversal time Charging burning shaft Charging regenerative shaft Lime discharge (shaft 1 + 2) Filling the rotating bucket (shaft 1 + 2)

S1

S2

To select this operating mode: - FIRING SYSTEM on - Select PRODUCTION - Select CHARGING DURING THE REVERSAL TIME - DISCHARGE on

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6.4.5

GENERAL INSTRUCTION & OPERATION Operation

Production mode “charging during burning time” This mode of operation is selected for continuous operation. With charging during the burning time it is possible to reduce the reversal time. This reduces pressure drops and the production volume can be increased. Time in minutes

1

2

3

4

5

6

7

8

9

10 11 12 13 14

Cycle time Burning time Fuel dosing time Burn-out time Reversal time Charging regenerative shaft Lime discharge (shaft 1 + 2) Filling the rotating bucket regenerative shaft

To select this operating mode: - FIRING SYSTEM on - Select PRODUCTION - Select CHARGING DURING THE BURNING TIME - DISCHARGE on

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6.5

GENERAL INSTRUCTION & OPERATION Operation

Reversal and charging sequences The following diagrams describe the automatic processes which are performed by the kiln control and material feed system, depending on the selected production mode. In the description of the reversing sequences, the term "burning shaft (BS)" is used for the kiln shaft which is currently being fired. The letters (RS) are therefore used to designate the shaft which was the regenerative shaft (RS). The reversal time always follows the burning time.

6.5.1

Production mode “charging during the reversal time” Reversal sequence, including charging and discharging Components

Action; effect

Reversal time (~ 57 s) 0s

Pre-relief flap (IF APPLICABLE)

Open

Relief flap Cooling air

Open (Extend hyd. cyl.)

-

Delay time

Relief flap combustion air

Open (Extend hyd. cyl.)

-

Release kiln pressure

-

Kiln completely depressurised

Pre-relief flap (IF APPLICABLE)

Close

Reversal flap (BS) BS  RS

Close combustion air side Waste gas side is opened (Extend hyd. cyl.)

Discharge flap (BS)

Open (Extend hyd. cyl.)

Discharge flap (RS)

Open (Extend hyd. cyl.)

-

Discharge lime into the hopper

-

Delay time

Discharge flap (BS)

Close (Retract hyd. cyl.)

Discharge flap (RS)

Close (Retract hyd. cyl.)

Shaft closing flap (BS) (type sideways)

Lift, open kiln shaft (Extend hyd. cyl.)

10 s

20 s

30 s

40 s

50 s

60 s

Move sideways (Extend hyd. cyl.) Shaft closing flap (RS) (type sideways)

Lift, open kiln shaft (Extend hyd. cyl.) Move sideways (Extend hyd. cyl.)

Shaft closing flap (BS) (type inwards)

Open kiln shaft (Extend hyd. cyl.)

Shaft closing flap (RS) (type inwards)

Open kiln shaft (Extend hyd. cyl.)

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Rotating bucket (BS)

Lower (Retract hyd. cyl.)

Rotating bucket (RS)

Lower (Retract hyd. cyl.)

-

Charge kiln with stone

-

Delay time

Rotating bucket (BS)

Lift skip (Extend hyd. cyl.)

Rotating bucket (RS)

Lift skip (Extend hyd. cyl.)

Shaft closing flap (BS) (type sideways)

Shaft closing flap (RS) (type sideways)

GENERAL INSTRUCTION & OPERATION Operation

Move to the centre (Retract hyd. cyl.) Set down, close kiln shaft (Retract hyd. cyl.) Move to the centre (Retract hyd. cyl.) Set down, close kiln shaft (Retract hyd. cyl.)

Shaft closing flap (BS) (type inwards)

Close kiln shaft (Retract hyd. cyl.)

Shaft closing flap (RS) (type inwards)

Close kiln shaft (Retract hyd. cyl.)

Reversal flap (RS) RS  BS

Open combustion air side Waste gas side is closed (Retract hyd. cyl.)

Relief flap combustion air

Close (Retract hyd. cyl.)

Relief flap cooling air

Close (Retract hyd. cyl.)

-

Build up kiln pressure

-

Delay time

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Fig. 56

GENERAL INSTRUCTION & OPERATION Operation

Production mode charging

Item

Description

Item

Description

A

Combustion air

G

Pre-relief flap

B

Cooling air

H

Waste gas

C

Air to atmosphere

J

Shaft closing flap

D

Relief flap: cooling air

K

Discharge flap

E

Relief flap: combustion air

L

Reversal flap: Filter / Direct chimney

F

Reversal flap: Combustion air / Waste gas

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6.5.2

GENERAL INSTRUCTION & OPERATION Operation

Production mode “Charging during burning time” Reversal sequence, including discharge Components

Reversal time (~ 25 s)

Action; effect 0s

Pre-relief flap (IF APPLICABLE)

Open

Relief flap cooling air

Open (Extend hyd. cyl.)

-

Delay time

Relief flap combustion air

Open (Extend hyd. cyl.)

-

Release kiln pressure

-

Kiln completely depressurised

Pre-relief flap (IF APPLICABLE)

Close

Reversal flap (BS)

Close combustion air side Waste gas side is opened (Extend hyd. cyl.)

Reversal flap (RS)

Open combustion air side Waste gas side is closed (Retract hyd. cyl.)

Discharge flap (BS)

Open (Extend hyd. cyl.)

Discharge flap (RS)

Open (Extend hyd. cyl.)

-

Discharge lime into the hopper

-

Delay time

Discharge flap (BS)

Close (Retract hyd. cyl.)

Discharge flap (RS)

Close (Retract hyd. cyl.)

Relief flap combustion air

Close (Retract hyd. cyl.)

Relief flap cooling air

Close (Retract hyd. cyl.)

-

Build up kiln pressure

-

Delay time

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20 s

30 s

40 s

50 s

60 s

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GENERAL INSTRUCTION & OPERATION Operation

Charging sequence during the burning time Charging time (~ 25 s)

Components

Action; effect

Waste gas fan

Increased speed; Maintain waste gas sub-pressure

0s

10 s 20 s 30 s 40 s 50 s 60 s

Lift, open kiln shaft Shaft closing flap (RS) (Extend hyd. cyl.) (type sideways) Move sideways (Extend hyd. cyl.) Shaft closing flap (RS) Open kiln shaft (type inwards) (Extend hyd. cyl.) Rotating bucket (RS)

Move downwards (Retract hyd. cyl.)

-

Charge kiln with stone

-

Delay time

Rotating bucket (RS)

Lift skip (Extend hyd. cyl.)

Move to the centre Shaft closing flap (RS) (Retract hyd. cyl.) (type sideways) Set down, close kiln shaft (Retract hyd. cyl.) Shaft closing flap (RS) Close kiln shaft (type inwards) (Retract hyd. cyl.) Waste gas fan

Reduce speed back to normal operation

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6.6

GENERAL INSTRUCTION & OPERATION Operation

Calculation of the process parameters (sample) Designation

Unit

Abbreviation Formula

Example Signal

Production

tpd

PR

400

Input

Factor lime / limestone

-

FLS

0.565

Input

Amount of stones per cycle

kg

SC

7’080

Input

Reversal time

s

RTn

25

Input

Burn-out time for solid or liquid fuel

s

BOTns

60

Input

Burn-out time for gaseous fuel

s

BOTng

10

Input

Specific heat input

kJ/kg lime

HI

3’300

Input

Heat input through solid or liquid fuel

%

HIS

0

Input

Lower calorific value Hu, solid or kJ/kg liquid fuel

CVns

0

Input

Stoichiometric combustion air volume, solid or liquid fuel

Nm /MJ

MA1s

0.2606

Input

Calorific value Hu, gaseous fuel

kJ/Nm

CVng

33’473

Input

Stoichiometric combustion air volume, gaseous fuel

Nm /MJ

MA1g

0.2675

Input

Air excess

-

EAF

1.10

Input

3

3

3

3

Cooling air factor (lime cooling)

Nm /kg lime

CAF

0.70

Input

Number of burner lances per shaft

-

NL

33

Input

Lance cooling air + transport air 3 Nm /h (per burner lance)

LCABSL

140

Input

Lime quantity per cycle

kg

LC

= FLS × SC

4’000

no signal

Number of kiln cycles per day

-

N

= PR × 1000 / LC

100

Output

Cycle time

s

CT

= 86400 / N

864

no signal

Burning time

s

BT

= CT - RTn

839

Output

Fuel dosing time, solid fuel

s

FFTs

= BT - BOTns

779

no signal

Fuel dosing time, gaseous fuel

s

FFTg

= BT - BOTng

829

no signal

Mass flow lime relative to burning time

kg / h

MFLBT

= LC × 3600 / BT

17’163

no signal

Mass flow lime relative to fuel dosing time, solid fuel

kg / h

MFLFFTs

= LC × 3600 / FFTs

18’485

no signal

Mass flow lime relative to fuel dosing time, gaseous fuel

kg / h

MFLFFTg

= LC × 3600 / FFTg

17’370

no signal

Heat quantity per cycle

MJ

HC

= LC × HI / 1000

13’200

Output

Fuel quantity per cycle, solid fuel

kg

FCs

= HIS / 100 × HC × 1000 / CVns

0

Output

Fuel quantity per cycle, gaseous fuel

Nm

FCg

= (100 - HIS) / 100 × HC × 1000 / CVng

394

Output

Fuel flow, set point, solid fuel

kg / h

FFns

= FCs × 3600 / FFTs

0

Output

3

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Designation

Unit 3

GENERAL INSTRUCTION & OPERATION Operation

Abbreviation Formula

Example Signal

Fuel flow,set point, gaseous fuel Nm /h

FFng

= FCg × 3600 / FFTg 1’712

Output

Heat capacity, solid fuel

kW

HFns

= FFns / 3600 × CVns

0

Output

Heat capacity, gaseous fuel

kW

HFng

= FFng / 3600 × CVng

15’923

Output

Combustion air stream nominal value

Nm /h

3

CombAFn

= 3.6 × (HFns × MA1s × EAF + HFng × MA + g × EAF)

16’867

Output

Combustion air stream through burner lances

Nm /h

3

LCABS

= NL × LCABLS

4’620

Output

Combustion air from main fans, including suspended cylinder

Nm /h

3

CuAFnM

= CombAFn - LCABF 12’247

Output

Cooling air flow, set point

Nm /h

3

CoolAFn

= MFLBT × CAF

12’014

Output

All input data can be entered in the visualisation system. The corresponding output data is displayed immediately. For a better understanding of the process, all of the other calculated results which do not appear in the visualisation system can be calculated according to the above table. All output data calculated by the PLC is used automatically by it as nominal values for controlling the kiln process. INFORMATION An EXCEL worksheet "Kiln Parameter Calculation" with the same design as the above table can be found on the attached CD-ROM. With this, you can check the calculations performed by the PLC.

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GENERAL INSTRUCTION & OPERATION Operation

6.7

Description of the Operational Procedures

6.7.1

Limestone charging The limestone charging is divided into two areas: - Filling the kiln hopper or weighing hopper - Filling the rotating bucket Filling the kiln hopper or weighing hopper The filling system for the kiln or weighing hopper is controlled by a separate sequence and can be set by means of a button in the "limestone charging" screen view to OFF or AUTO. If the sequence is switched to AUTO, limestone is automatically topped up. All of the necessary limestone charging conveyors, belt conveyors and screens are automatically started or stopped by the PLC. The charging and belt conveyors are stopped immediately as soon as the weight of the stones in the kiln or weighing hopper has reached the nominal value. INFORMATION Local operation is only intended for testing purposes and should not be used during normal operation. Before the local start-up of a charging or belt conveyor, it must be ensured that the downstream conveying systems and containers cannot be overfilled. Filling the rotating bucket The filling of the rotating bucket is controlled by means of an individual PLC sequence and can be set to OFF or AUTO by a button in the "KILN" screen view. With the AUTO setting, limestone is automatically topped up from the kiln or weighing hopper via the reverse conveyor into the rotating buckets after these have been emptied and reached their upper position.

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6.7.3

GENERAL INSTRUCTION & OPERATION Operation

Filling the kiln Ensure that no emergency stop button is activated. Set the following kiln parameters: Kiln capacity

Maximum

Factor lime / limestone

0.575

Adjust the quantity of limestone per cycle such that the following number of cycles is set.

100 to 120 cycles/day

Reversal time, nominal

60 - 90

Turn all key-operated switches on the local controls to AUTO operation. Select "HEATING-UP" kiln operation mode Turn stone charging of the silo to AUTO sequence. Set kiln charging to AUTO. Turn filling of the rotating bucket to AUTO. Turn lime discharge system to AUTO. Start hydraulic pumps 1 and 2. Start kiln. NOTE The discharge tables may become jammed as a result of the friction of the compressed limestone when the kiln is being filled! The discharge tables work automatically only when the nominal stone level is reached. In order to prevent the limestone becoming compressed in the shafts, the discharge tables must be moved every hour while the kiln is being filled. NOTE The refractory lining may be damaged! Heat up of the kiln as soon as the shafts are filled with limestone. The moisture in the limestone can damage the refractory lining of the kiln.

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6.7.4

GENERAL INSTRUCTION & OPERATION Operation

Start-up process NOTE Risks at first commissioning! Start-up of the kiln and the first normal kiln operation must be monitored by a specialist engineer of the manufacturer. This specialist engineer is also responsible for the training of the kiln operating personnel. For all technical issues regarding the kiln operation, please contact the manufacturer. Prerequisites Adjust the suspended cylinder cooling air flaps so that the hot air is discharged into the atmosphere (optional). Close the suspended cylinder cooling air flap to the combustion air. Open venting flap. Open the evaporation openings before firing up the start-up burner. Round kilns: poke hole platform and burner lance platform Rectangular kilns: above the connecting channel around the kiln. All key-operated switches at the local operating units must be set to "AUTO". Round kilns: fill approx. 100kg of dry wood into the connecting channel. Rectangular kilns: fill approx. 50kg of dry wood into the connecting channel. A torch must be prepared for the manual firing up of the wood within the connecting channel.

Fig. 57

Firing-up process

Item

Description

Item

Description

A

Connecting channel

C

Wood

B

Start-up burner

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GENERAL INSTRUCTION & OPERATION Operation

Start-up the kiln NOTE The kiln may be damaged by temperature fluctuations! The start-up process must not be interrupted. Upon completion of the startup process, the kiln must be fired via the burner lances. Any temperature drop during the start-up phase must be avoided. Set the following kiln parameters: Kiln capacity

20 t

Factor lime / limestone

0.575

Amount of stones per cycle

See start-up table

Reversal time, nominal

60 s

Cycle time

See start-up table

Stone quantity

See start-up table

Start cooling air system for suspended cylinders (option). Do not route the waste air into the combustion air duct. Select kiln-operating mode START UP. Set blower to operating mode MANUAL. Set kiln feed system to CHARGE DURING REVERSAL TIME. Set stone handling sequence to AUTO. Set discharge system to AUTO. Start hydraulic pumps. Set reversal flap filter/ direct chimney [K] to direct chimney. Open the start-up valve for the combustion air [F]. Close the start-up valve for the fuel [E]. Partially close start-up flap combustion air [C]. Start combustion air blower at minimum speed. Start kiln. Use push button within the visualisation system to bridge the flame monitor. Ignite wood in the connecting channel. Use push button within the visualisation system to start the firing system.

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GENERAL INSTRUCTION & OPERATION Operation

Open fuel shut-off valve. Carefully open the start-up valve for the fuel [E]. Use the inspection glass to check if the flame has been kindled. NOTE As long as the flame monitor has not been activated, monitor the flame permanently. If the flame goes out, interrupt the fuel supply to the start-up burner immediately by closing the start-up valve. Vent the kiln by means of combustion air and cooling air. Set flaps for the combustion air and fuel so the flame is yellow. Close poke holes and monitor the flame regularly. If the flame is stable, activate the flame monitor via the push button within the visualisation system Set the suspended cylinder cooling air to minimum speed (option). Set kiln operation so that the correct temperature increase is achieved according to the start-up diagram. Refer to the following table for the recommended values for the start-up process. These are to be considered the guide value to achieve the curve from the start-up diagram. If 2 start-up burners have been installed (rectangular kilns with two connecting channels), 50% of the recommended values must be set at each burner. The fuel distribution must be set so that both channel temperatures are identical.

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GENERAL INSTRUCTION & OPERATION Operation

Fig. 58

Heating-up the kiln

Item

Description

Item

Description

A

Combustion air from the blower house

F

Combustion air start-up valve

B

Fuel

G

Start-up burner

C

Relief flap

H

Reversal flap: Combustion air / Waste gas

D

Start-up flap of combustion air

J

Combustion air in the kiln

E

Fuel start-up valve

K

Reversal flap: Filter / Direct chimney

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GENERAL INSTRUCTION & OPERATION Operation

Start-up diagram

Fig. 59

Start-up diagram

Start-up table Time after start [h]

Temperature [°C]

Heat flow [MJ/h]

Combustion air [Nm³/h]

Cooling air [Nm³/h]

Cycle time [s]

Stone quantity [kg/cycle]

Kiln type E2, E3 0-2

0

1800

300 - 500

0 / min.

3600

1600

2 -24

0 - 600

2500

1000 - 5000

0 / min.

1800

800

24 - 48

600

2300

3000 - 7000

0 / min.

1800

800

48 - 72

600 - 900

4000

5000 - 10000

0 / min.

1800

800

Kiln type E4, E5, E6, R1P, R2P, R3P, R3S, F1P, F2P, F3P, F2S, F3S 0-2

0

2900

500 - 1000

0 / min.

3600

1600

2 -24

0 - 600

4000

2000 - 7000

0 / min.

1800

800

24 - 48

600

3600

6000 - 10000

0 / min.

1800

800

48 to 72

600 - 900

5000

6000 - 15000

0 / min.

1800

800

Kiln type R4P, R4S and R5S 0-2

0

3600

750 - 1300

0 / min.

3600

1600

2 -24

0 - 600

5000

2500 - 10000

0 / min.

1800

800

24 - 48

600

4700

9000 - 13000

0 / min.

1800

800

48 to 72

600 - 900

6800

9000 - 20000

0 / min.

1800

800

- Increase the air and the fuel supply rates step by step. In doing so, watch the flame of the start-up burner. If the flame becomes unstable, adjust the fuel supply rate. - In particular when using pillar kilns, preheating has to be carried out without cooling air, as otherwise the pillars are not sufficiently warmed. Regular checks must be performed in the blower house in order to ensure that no flue gases are flowing back through the cooling air blowers. If necessary, switch on one of the cooling air blowers at minimum speed.

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GENERAL INSTRUCTION & OPERATION Operation

- The start-up burner is in continuous operation. - Upon start-up of the kiln, the start-up burner is removed and replaced by the pyrometer.

NOTE Any local overheating within the connecting channel must be avoided without fail. If necessary, the temperature curve can be adjusted after consulting Maerz. INFORMATION In order to reach the required temperature increase within the kiln, the values of the start-up table may be changed slightly.

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6.7.5

GENERAL INSTRUCTION & OPERATION Operation

Production operation NOTE The start-up process must be completed before the kiln is changed over to normal operation and the firing system with burner lance is started. Preconditions for production mode - The temperature in the connecting channel or annular channel must be at least 900°C. - The evaporation openings must be closed before starting the lance operation, since otherwise the insulation may suffer damage. - The following table shows the temperature required for the spontaneous ignition of certain fuels. The specific ignition temperatures must be specified by the fuel supplier. Fuel

Ignition temperature

Natural gas

550 to 600 °C

Fuel oil

210 to 260 °C

Coal

230 to 500 °C

Lean gas

300 to 600 °C

NOTE For solid and liquid fuels, the minimum ignition temperatures must be reached at the lance tips before you may switch over to lance operation. If the ignition temperature at the lance tips is not reached, start-up by means of the start-up burner must be continued. In doing so, the channel temperature must be held at 900°C. The temperature on the lance tips can be raised by increasing the quantity of combustion air volume and fuel.

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Production operation The kiln parameters are to be set in accordance with the EXCEL worksheet "Kiln Parameter Calculation" on the enclosed CD-ROM. Open the start-up flap in the combustion air duct. Close the start-up valve for the combustion air. Close the start-up valve for the fuel in the direction of the start-up burner Hydraulic pumps to AUTO Blowers to AUTO. Select kiln-operating mode PRODUCTION. Set the kiln feed system to CHARGING DURING REVERSAL TIME or to CHARGING REGENERATIVE SHAFT. Set to rotating bucket sequence to AUTO. Set stone handling to AUTO. Set discharge system to AUTO. Set firing system to AUTO. Start lance cooling air blower. Set air blast units to ACTIVATE. Leave reversal flap filter / chimney in chimney position. INFORMATION The kiln must be monitored by the operating personnel at all times. Check in regular intervals whether all systems are running and whether the firing is functioning properly via the burner lances. Perform regular inspection tours. Monitor the process continuously and change the parameters if necessary. The setting of the process parameters influences the quality of the lime produced. NOTE Danger if the parameters are outside the permitted capacity limits. The parameters must be set in accordance with the limits stated in the chapter Technical Data.

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6.8

GENERAL INSTRUCTION & OPERATION Operation

Preconditions for production operation The following sections contain instructions for the correct operation of the kiln and the production of high-quality lime.

6.8.1

Basic recommendations - Only use raw materials and fuel which meet the specifications in the chapter Technical Data. Raw material and fuels which do not meet the specifications always produce results which are not desirable. - A laboratory with appropriate instruments and trained personnel has been set up for analysing the quality of the lime. - Keep the connecting channel and ring channels clean at all times and remove any dust and lime deposits. - Check the scales for limestone and solid fuel regularly so that the charging of the kiln with the specified quantities is ensured. - The following measurements also must to be checked regularly: quantity of fuel, quantity of combustion air volume, etc. - Have the fuel and raw materials analysed at regular intervals. - Start kiln: Start the stone handling first so that all stone hoppers are filled. - Stopping the kiln: Stop the kiln shortly before the end of the burning time, e.g. 5 to 10 seconds. By doing so, it is ensured that any changes to the parameters are taken over and the cycle can be completed properly.

6.8.2

Key factors for the lime burning process in the lime kiln General information - Operate the kiln continuously and with as few interruptions as possible. - Take lime samples every 8 hours; these must be a mixture from the two shafts. The sample quantity must not be less than 50 kg. Divide and crush the total quantity in order to obtain a representative sample for the laboratory. Have the average CO2 content and the reactivity of the lime analysed in the laboratory. - If the average quality is not in line with specifications, or in the case of abnormal temperature or pressure developments or other faulty kiln operations, the quality of the lime should be subjected to a visual inspection at the discharge table. Sampling must be carried out quickly and should result in kiln stoppages of not more than 15 minutes.

6.8.3

Adjustment of the cooling air - The distribution of the cooling air should be adjusted in such a way that the total air flow is as low as possible. Normally, a lime cooling air factor of 0.64 Nm3 / kg lime is set. In the case of fine lime kilns a cooling air factor of 0.70 Nm3 / kg lime is usually set. - The cooling air distribution must be set in such a way that the lime temperature at each of the two discharge tables is equal.

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- Set the cooling air distribution so that 50% of the volume is delivered to the burning shaft and the other 50% to the regenerative shaft. - An increase in the cooling air flow rate increases the waste gas temperature and the specific energy consumption. - If there is too much cooling air, the burnt lime may re-carbonise or hydrate in the cooling zone. This may result in worse lime quality. 6.8.4

Setting the Heat Input - The heat input must be adjusted in such a way that the desired CO2 content in the lime is reached. - The heat input depends on the selected production output of the kiln. As the heat loss on the kiln shell remains the same for different kiln capacities, the heat input at 50% kiln capacity is approximately 50 kCal / kg (approx. 200 kJ / kg) higher than for a production output of 100%. - The heat input depends on the chemical composition and moisture. A higher proportion of CaCO3 requires a higher input of energy. INFORMATION The burnt lime should be analysed at least every 8 hours. The kiln operator must have access to the quality statistics from the laboratory tests at all times in order to adjust the kiln parameters if necessary. Depending on the production output, the effects of parameter changes on the quality of the lime only become visible after 24 hours (dwell time of a particle in the kiln). INFORMATION The heat input does not have to be continually adjusted owing to fluctuating moisture values of the raw material. The evaporation energy of water is more or less the same as the reaction energy of CaCO3. - The required heat input and the waste gas temperature depend on the cooling air flow rate. - The required heat input also depends on the size of the raw material. Larger raw material results in greater heat input.

6.8.5

Adjusting the Air Excess Factor - Set the air excess factor such that the flames do not pass through the gas channels. - The temperatures in the entire burning zone are approximately 950 °C. - Too much excess air results in an excess temperature in the upper section of the burning zone. This can cause malfunctions to kiln operation. - Too little excess air causes an excessive temperature in the channel and a higher CO content in the waste gas.

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NOTE Damage to the refractory lining of the crossover channel! Set the air excess in such a way that the temperatures remain below the maximum permitted value for the refractory lining. WARNING Danger of explosion in the waste gas duct and filter! Set the excess air in such a way that an excess CO content in the waste gas is avoided. The correct level of excess air is determined while the kiln is starting up. To this purpose, the temperature is carefully monitored with the optical pyrometer, which is installed on the connecting channel. Temperature monitoring should always be carried out if the setting of the excess air has been changed. - A flat temperature curve indicates too much excess air. - A temperature curve with fluctuations of more than 50°C indicates that the excess air is too small. - An increase in the production outputs or large limestone results in higher channel temperatures.

Fig. 60

Ideal temperature curve for different kiln production outputs (typical solid fuel)

Item

Description

Item

Description

FFT

Fuel dosing time

RT

Reversal time

BOT

Burn-out time

Fig. 61

Temperature curve for kiln production output (typical gas)

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6.8.6

GENERAL INSTRUCTION & OPERATION Operation

Setting the Fuel Parameters The fuel parameters include the following: - lower calorific value (LCV) - stoichiometric combustion air volume (Nm3 air / MJ fuel) The fuel parameters correspond to the laboratory results of the specifications of the fuel supplier. INFORMATION The lower calorific value is of major importance and has to be checked every 24 hours. If the required stoichiometric combustion air volume is not known, this can be calculated according to the chemical composition of the fuel.

6.8.7

Setting the Reversal Time - The reversal time is entered manually. During cold commissioning - and later during operation - the minimum reversal time is measured. The input value should be equal to or higher than the measured time. - The reversal time depends on the type of charging. With CHARGING DURING THE REVERSAL TIME, the reversal time is higher than in the case of CHARGING DURING THE BURNING TIME. INFORMATION A changeover between CHARGING DURING THE REVERSAL TIME OFF to CHARGING DURING THE BURNING TIME ON means that the reversal time has to be adjusted.

6.8.8

Setting the Nominal Burn-out Time - Set the nominal burn-out time according to the following table: Fuel

Nominal burn-out time

Fuel oil

20 to 50 s

Coal

60 to 90 s

Natural gas

15 s

Lean gas

20 s

- Whenever the actual burn-out time is too short or too long, an alarm is triggered. - If the burn-out time is too short, the fuel supply is inadequate. If the burn-out time is too long, the fuel supply is too high. - When the smallest possible burn-out time is set, this must not be below the values in the above table.

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INFORMATION Adjust the actual burn-out time if the nominal burn-out time deviates from the actual burn-out time by more than + / -5 seconds. In order to determine the shortest burn-out time, please proceed as follows: Fuel

Nominal burn-out time

Liquid fuels

Set 50 s Check the CO concentration in the kiln waste gas Check the fuel pipes of the lances after the burnout time has expired. The burn-out time can be reduced to the minimum as long as the fuel pipes remain clean and the CO concentrations in the waste gas do not exceed the specified limit values.

Solid fuels

Set 90 s Check the CO concentration in the kiln waste gas Check the fuel concentration in the filter dust. The burn-out time can be reduced to the minimum as long as the CO concentrations in the waste gas and the fuel concentration in the filter dust do not exceed the specified limit values.

Natural gas

Set 15 s No further action required.

Lean gas

Set 20 s No further action required.

6.8.9

Setting the discharge tables Set the discharge tables in such a way that the lime discharge in the respective burning shaft is somewhat higher than in the regenerative shaft.

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6.9

Kiln stoppage and restarting

6.9.1

Kiln stoppage

GENERAL INSTRUCTION & OPERATION Operation

Select kiln stoppage in the visualisation system in order to stop the kiln. The kiln control system automatically carries out the following steps: - The fuel supply is immediately interrupted. - The burn-out time begins immediately, the kiln is flushed with combustion air, cooling air and lance cooling air for the duration of the burn-out time. - The kiln is depressurised using the relief flaps for combustion air and cooling air. - The blowers for combustion air, cooling air and transport air (option) are stopped. - The lance cooling air is switched off after 15 minutes. - The combustion air / waste gas reversal flaps are moved to the position waste gas to the chimney. - The filter / direct chimney reversal flap is moved to the direct chimney position. INFORMATION If the kiln is stopped, all systems remain in AUTO mode. This means: All containers continue to be filled with limestone until they are full. The lime discharge system continues to discharge lime. The hydraulic system continues working. NOTE During long stops the lime may form clumps! Discharge lime manually from time to time in order to prevent clumping in the shafts. The following table shows the maximum quantities which can be discharged during a kiln stoppage: - Day 1:

6 tonnes

- Day 2:

2 tonnes

- Day 3:

1 tonne

- Day 4:

1 tonne

- Day 5:

0 tonnes

With some kilns this manual discharge is not necessary, as they work even better without it. However, you have to test this yourself for your kiln.

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NOTE The following has to be borne in mind in the case of kilns with suspended cylinders! As the temperatures in the kiln remain at 1000°C for a long time after a stoppage, the cooling system of the suspended cylinders has to continue running. Do not switch off the cooling system of the suspended cylinders. Otherwise, the suspended cylinders can be damaged. If the cooling system of the suspended cylinders fails, the emergency cooling system is automatically switched on (via PLC). In any case the kiln operator must check locally whether the emergency cooling system has switched on. 6.9.2

Restarting Select kiln start in the visualisation system in order to start up the kiln again after a stoppage. The start-up is carried out as described in the following: Ensure that everyone is back in the control cabin and nobody is located in the vicinity of the kiln. Check whether all systems work perfectly. NOTE Ensure that the temperature in the connecting channel is over 750°C. For solid and liquid fuels: Ensure that the lance temperature is 50°C above the ignition temperature. Set all systems that have previously been switched to OFF to AUTO. If lime was discharged during the stoppage, replenish the shafts with limestone until the filling level is normal again. INFORMATION The energy loss through the kiln shell during the stoppage has a negative effect on the quality of the lime. The loss through the shell cannot be compensated for by a short-term increase in the heat input.

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6.9.3

GENERAL INSTRUCTION & OPERATION Operation

Kiln stoppage by an alarm In a dangerous situation the kiln is always stopped automatically. This can be caused by process limit values being exceeded. NOTE Avoid kiln stoppages by an alarm! The initial setting of the limit values must be carried out in the presence of a specialist engineer commissioned by the manufacturer. All subsequent changes to the settings by the personnel operating the kiln require a high level of professional knowledge. In cases of doubt the manufacturer should be consulted. INFORMATION As soon as the problem which led to the kiln being switched off has been rectified, the kiln operator must restart all systems in accordance with the above instructions.

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6.9.4

GENERAL INSTRUCTION & OPERATION Operation

Kiln stoppage in the case of a power cut In the case of a power cut, all systems are stopped, with the exception of the PLC and visualisation system. The PLC and the visualisation system have a UPS (uninterruptible power supply) and remain in operation for at least 10 minutes. A dangerous situation in the mechanical system cannot occur. - Where necessary, flaps (in particular the discharge flaps) are closed by means of counterweights and without any hydraulic pressure. - Certain types of kiln (depending on the fuel used) require an emergency power generator which is started automatically within one minute. The following systems are switched on by such an emergency power generator: - The kiln control system - One of the hydraulic pumps. Suspended cylinders (if applicable) NOTE As the temperatures in the kiln remain at 1000°C for a long time after a stoppage, the cooling system of the suspended cylinders has to continue running after a power cut. Otherwise, the suspended cylinders can be damaged. In the case of a power cut, the emergency cooling system is automatically switched on (via PLC). In all cases the kiln controller must check locally: - whether the emergency cooling system has switched on. - whether all of the flaps are in the right position. INFORMATION As soon as the main current is available again, the kiln operator must put the system back into operation as soon as possible in accordance with the recommendations contained in the above sections.

6.9.5

Emptying the kiln NOTE Emptying the kiln reduces the lifetime of the refractory brick lining! Complete emptying of the kiln reduces the lifetime of the refractory brick lining significantly. The kiln should never be emptied completely unless this is absolutely necessary. When the kiln is switched off in order to carry out repairs, it is often possible to empty the kiln only partially. It takes approximately 2 days to empty the kiln. Ensure that all emergency-off pushbuttons are set to ON.

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Set the kiln to PRODUCTION MODE. Set the kiln operation to OFF Set stone handling to ON Set the filling process for the rotating bucket to AUTO Set the kiln discharge system to AUTO. Start hydraulic pump 1 and / or 2 Switch the reversal flaps to chimney (kiln to stop) Open the doors of the discharge table (in order to create natural ventilation in the kiln). Close the doors in the case of waste gas temperatures > 200°C and charge with cold lime Manual discharging by means of the manual key Open the discharge flaps for the lime discharge from time to time in order to discharge the lime - In the case of a discharge temperature of more than 200°C -> stop manual discharging. - If all discharge temperatures are below 200°C -> start manual discharging. NOTE High waste gas temperatures may damage the seals of the reversal flaps For waste gas temperatures of more than 195°C -> close the doors of the discharge table in order to stop the ventilation. If all waste gas temperatures are below 180°C -> open the doors of the discharge table in order to restart the natural ventilation.

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6.10

Fine Lime Charging

6.10.1

Effect on lime quality

GENERAL INSTRUCTION & OPERATION Operation

Heat distribution Uniform product quality requires an even heat distribution over the cross-section of the shaft. This effect is not only influenced by uniform fuel distribution through the lances, but also by the dispersion of the flames in the burning zone and the gas flow in the kiln shafts, which in turn are primarily determined by the distribution of the different fractions of the kiln charge over the shaft cross-section. It is therefore essential to control the distribution of the limestone to achieve the desired uniformity of flame dispersion and gas flow. Segregation by stone Segregation by stone size is caused by discharge of limestone from a belt, skip hoist or similar device. The larger the shaft cross-section, the greater the problem. The figure below shows a vertical section of a kiln shaft without any device for regular stone distribution. It is obvious that coarse particles are concentrating on one side of the shaft and fine particle fractions on the other. The gas flow pattern in the kiln shafts depends on the specific resistance of the material column, i.e. areas with small fractions have a higher resistance and therefore a lower gas flow than areas with larger fractions. With a poorly distributed kiln charge, the temperature differences over the shaft cross-section definitely have a detrimental effect on the product quality and on the operating behaviour of the lime kiln.

Fig. 62

Stone size segregation without distribution device (typical)

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6.10.2

GENERAL INSTRUCTION & OPERATION Operation

Distribution system For kilns with a small stone size fraction up to 1:1.5, it is possible to distribute the kiln charge with sufficient uniformity by installing comparatively simple charging guides. However, a more sophisticated rotary hopper stone distribution system is necessary for larger stone size fractions of up to 1:2 according to the picture below.

6.10.3

Item

Description

1

Kiln hopper

2

Vibration feeder

3

Reversible conveyor belt

4

Rotating bucket

5

Stone distributor

Kiln charging method There are 3 different charging methods to improve stone distribution: - Sandwich method - Fine lime method - Sandwich and fine lime method

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GENERAL INSTRUCTION & OPERATION Operation

Sandwich method In most cases, it is advantageous for lime producers to use as much as possible of the quarried limestone to feed the lime kilns. By applying the sandwich method it is possible to use limestone with a very high ratio of the largest to the smallest limestone particles: The raw material is separated into two fractions and alternately charged to the lime kiln with a defined number of layers containing the large fraction to be followed by a defined number of layers containing the small fraction. Requirements Two bins with different stone sizes must be available to charge the kiln with a controlled quantity of each grain size. Functional description The following example demonstrates the effect of the void space in the packed material bed in the kiln shaft on the pressure drop:

Fig. 63

Different pressure drops using different charging methods (typical)

Example 1

Example 2

Limestone distribution

mixed and well distributed

divided into 2 fractions

Pressure drop p

200 mbar

150 mbar

Void space

38%

42%

Energy consumption

more

less

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Advantages - Optimal yield from quarried limestone - Less pressure drop in the kiln - Lower electric energy consumption - Less segregation of the limestone during the charging process - Improved heat distribution over the cross-section of the kiln shafts Application In practical kiln operation it is also possible to make use of this technique to significantly lower the electric energy consumption of the kiln. Two different limestone fractions are charged in layers of reasonable height. The number of layers with small stone and the number of layers with large stone can be selected by the kiln operating person.

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Fine lime method To optimize regular stone size distribution over the cross-section of the kiln, additionally to the rotary hopper, a pivotable stone distribution flap is installed in the fine lime kiln. By changing the position after each discharge from of a rotary hopper stone is discharged alternately to the center of the shaft and to the outside. This feature improves linear stone distribution between inside and outside of the shaft. Also the quality of burnt lime can be improved by adjusting different stone sizes between center and outside of the shaft.

Fig. 64

Stone distribution flap (typical)

Item

Description

1

Stone distributor (swivel-mounted)

Requirements Two bins with different stone sizes must be available to charge the kiln with a controlled quantity of each grain size.

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2-fraction stone charging

Fig. 65

2-fraction stone charging (typical)

Item

Description

1

Stone fraction 1 (for example 27–40 mm)

2

Stone fraction 2 (for expample 15–27 mm)

A

1 layer = 2 rotary hoppers (1 × inside, 1 × outside)

B

3 to 4 layers = 6 to 8 rotary hoppers (each layer 1 × inside, 1 × outside)

Fig. 66

Typical visualization picture of charging with 2 fractions

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GENERAL INSTRUCTION & OPERATION Operation

Sandwich and fine lime method Larger ranges of grain size, for example 15 to 80 mm must be screened into 3 fractions and charged accordingly. Requirements 3 bins with different stone sizes must be available to charge the kiln with a controlled quantity of each grain size. 3-fraction stone charging Best results regarding quantity of layers and grain sizes must be determined by trial. The diagram below shows an example:

Fig. 67

3-fraction stone charging (typical)

Item

Description

1

Stone fraction 1, for example 27-40 mm

2

Stone fraction 2, for example 15-27 mm

3

Stone fraction 3, for example 40-80 mm

A

1 layer = 2 rotary hoppers (1 × inside, 1 × outside)

B

3 to 4 layers = 6 to 8 rotary hoppers (each layer 1 × inside, 1 × outside)

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Fig. 68

GENERAL INSTRUCTION & OPERATION Operation

Typical visualization picture of charging with 3 fractions

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7

GENERAL INSTRUCTION & OPERATION Malfunction

Malfunction Malfunctions of electrical appliances may only be eliminated by qualified technicians. The same applies to malfunctions in the fields of mechanics, pneumatics, and hydraulics. Inform the manufacturer about malfunctions which cannot be removed by the measures described.

7.1

Safety WARNING Danger of injury! Improper troubleshooting may lead to severe injury or even death and/or property damage. Therefore, troubleshooting is to be carried out exclusively by trained and authorised technical staff complying with safety instructions! When performing maintenance, make sure to observe the following: - Shut down the kiln and lock against restarting - Do not perform any work unless the kiln has been shut down. - Securely lock moving parts. - Attach a well-visible sign warning of work in progress to the main switch and the access areas of the kiln (see figure).

Fig. 69

Sign warning of work in progress (typical)

WARNING Danger of injury! An accidental start of the machine during maintenance or repairs may cause serious injuries, permanent bodily impairment or death! Therefore: Remove the key from the key switch and keep it out of reach of third parties by storing it in your pocket, until all work has been completed. Secure the main switch with a padlock to prevent the machine from restarting, remove the key and keep it. Inform the machine operator as well as the supervisor about the expected scope and duration of the maintenance work.

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7.2

GENERAL INSTRUCTION & OPERATION Malfunction

Steps to be taken in the event of a failure In general In the event of a failure implying immediate danger to persons, property and / or operational safety, immediately stop the kiln using the emergency process stop function. In the event of failures not implying such type of danger, shut down the kiln using the operator, disconnect it from the power supply, and lock against restarting. Immediately notify the local person in charge of the failure. Trained and authorized staff must determine the type and scope of the failure as well as its cause and eliminate the failure. INFORMATION For detailed descriptions of the necessary tasks to be performed for each individual component, refer to Instruction manual II – Description of Components. For information on the visualization system and the alarm messages, please refer to the Software Documentation.

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7.3

GENERAL INSTRUCTION & OPERATION Malfunction

Alarm systems The kiln is equipped with the following alarm systems: - Alarm system of the process visualization system - Signal horn in the control room and in the discharge table area (optionally)

Fig. 70

Example of an alarm page (typical)

This page shows all active alarms to be checked and processed. The alarm archive lists and stores all alarms that have already been acknowledged. NOTICE Danger caused by unjustified acknowledgment! Take alarm messages seriously at all times. They may highlight dangerous situations. Never acknowledge an alarm message without having removed its cause. The manufacturer cannot assume any liability for damage or processing errors caused by failure to acknowledge alarm messages.

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GENERAL INSTRUCTION & OPERATION Malfunction

Alarms are divided into 3 different groups: - Kiln alarms (red background) - Lime discharge (green background) - Limestone alarms (orange background) Depending on the type of alarm, automatic sequencing is either stopped, or merely an alarm will be triggered. In any event, the kiln attendant must localize and solve the problem before acknowledging the alarm and continuing kiln operation either automatically or manually INFORMATION The Software Documentation contains a list of all alarms.

7.3.1

Failure of machine components INFORMATION For the steps necessary to remove a failure of individual machine components, please refer to the applicable Operating Instructions and Documentation of the components involved.

7.3.2

Failure of the machine's control system In the event of an error or failure of the machine's control system (hardware defect, software error), shut down the machine immediately by pushing the emergency process stop button. If necessary, shut down the machine manually.

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7.4

GENERAL INSTRUCTION & OPERATION Malfunction

Restart after failure WARNING Risk of injury! An accidental start of the machine after a failure has been removed may lead to serious personal injury. Before restarting the machine, check: - whether the failure and its cause have been removed completely, - all safety devices have been properly installed and are in correct technical and functional condition, - that nobody is inside the machine's danger zone. After resolving a failure: Acknowledge the failure on the process screen of the PC terminal and, if applicable, acknowledge the emergency process stop of the respective machine component. Make sure that nobody is inside the kiln area. Start up the machine (see chapter Operation).

7.5

Steps for troubleshooting In addition to the failures indicated by the visualization system, process errors may occur that may have a negative impact on the finished product. The following list contains possible process errors and their probable causes as well as effective countermeasures. INFORMATION As the processes performed by the lime kiln are extremely complex, the following list can only contain the most common process errors. It is impossible to list all possible errors and their combinations. In case of problems or doubts when operating the lime kiln, ask the manufacturer for assistance. NOTICE It is the sole responsibility of the kiln operating person to decide whether to act by him or herself or to request technical advice and assistance from the manufacturer. In the event of an erroneous decision in this respect, the manufacturer cannot be held liable for any accidents or damage thus caused.

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Issue

Possible cause

Concentrations of residual Insufficient heat input CO2 in lime of both shafts too high

GENERAL INSTRUCTION & OPERATION Malfunction

Countermeasure Before increasing the heat input, make sure there is no other cause for this problem

Too much cooling air

Reduce cooling air

Wrong cooling air distribution

Set correct amount of cooling air to be supplied to the centre of the shafts

Waste gas temperature too high Increase stone level in shafts, reduce cooling air Limestone not to specification

Provide limestone according to specifications

Non-uniform burning temperature throughout burning zone

Adjust excess air correctly

Non-uniform burning temperature over shaft crosssection

Check fuel distribution

Wrong portions or wrong distribution of small and large stone fractions (fine lime kilns)

Adjust stone distribution

Concentrations of residual Too much heat input CO2 in lime of both shafts too low Concentrations of residual CO2 in lime of one shaft too high

Reduce heat input

Different amounts of limestone in Correct stone weighing system shaft 1 & 2 Different amounts of fuel in shaft Check for clogged burner lances 1&2 or fuel supply lines Correct fuel dosing system Different amounts of combustion Replace silicone rubber gaskets air in shaft 1 & 2 on reverse flaps Check air supply system for leaks Wrong cooling air distribution

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Set cooling air to the correct value

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GENERAL INSTRUCTION & OPERATION Malfunction

Issue

Possible cause

Countermeasure

Non-uniform lime quality at the discharge tables

Non-uniform burning temperature over shaft crosssection

Check for clogged burner lances and fuel supply lines Check fuel supply in each shaft

Material in burning zone sticking Check for over-burnt lumps of together lime, and reduce heat input if necessary.

Insufficient kiln production rate

Wrong cooling air distribution

Set correct amount of cooling air to be supplied to the centre of the shafts

Wrong stone distribution

Adjust stone distribution

Channels partially clogged

Clean connecting and ring channels

Operating pressure too high

Reduce heat input, if possible Reduce air volume, if possible Reduce reversal time Reduce burn-out time, if possible Provide limestone according to specifications

Burning temperature too high Heat input too high

Reduce heat input

Wrong excess air setting

Set correct excess air value

Lumps of lime sticking together

Reduce heat input

Stone size too large

Provide limestone according to specifications

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Issue

Possible cause

Burning temperature too low Heat input too low

Operating pressure too high

Operating pressures too low

Different waste gas temperatures in shaft 1 & 2

GENERAL INSTRUCTION & OPERATION Malfunction

Countermeasure Check whether excess air is adjusted correctly. If necessary, increase heat input. But first ensure that there is no other cause for this problem.

Wrong excess air setting

Set correct excess air value.

Air volume too large

Reduce air volume if possible

Heat input too high

Reduce heat input if possible

Burn-out time too long

Reduce burn-out time if possible

Reversal time too long

Reduce reversal time (hydraulics)

Limestone not to specification

Provide limestone according to specifications

Channels partially clogged

Clean connecting and ring channels

Leakage in air, hot gas, or waste Check systems for leaks gas lines Not all blowers operating, or failure of one blower

Check all blowers and all connected devices such as nonreturn valves, pressure relief valves, and flexible connections

Wrong cooling air distribution

Set cooling air distribution to the correct value

Different amounts of limestone supplied to the shafts

Correct stone weighing and charging system

Different amounts of fuel supplied to the shafts

Check the lances for obstructions Correct fuel dosing system

Different amounts of combustion Replace silicone rubber gaskets air supplied to the shafts on reverse flaps Check air supply system for leaks Material in burning zone sticking Reduce heat input and notify the or clogging together manufacturer

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Issue

Possible cause

Lime temperatures in shaft 1 Wrong cooling air distribution & 2 different or too high Different lime qualities

GENERAL INSTRUCTION & OPERATION Malfunction

Countermeasure Set cooling air distribution to the correct value See similar items in this table

Material in burning zone sticking Reduce heat input and notify the or clogging together manufacturer Different operating pressures Wrong cooling air distribution in shaft 1 & 2

Set cooling air distribution to correct value

Different amounts of limestone supplied to the shafts

Correct stone weighing and charging system

Different amounts of fuels supplied to the shafts

Check the lances for obstructions Correct fuel dosing system

Different amounts of combustion Replace silicone rubber gaskets air supplied to the shafts on reverse flaps Check air supply system for leaks Material in burning zone sticking Reduce heat input and notify the or clogging together manufacturer Material inside the shafts not Burning temperature in upper Adjust excess air correctly moving downwards part of the burning zone too high No lime discharged after kiln shut down

Build up and release pressure inside the kiln

Material in burning zone sticking Reduce heat input and notify the or clogging together manufacturer Discharge system not set to optimum values

Adjust discharge system such that extended idle times at the discharge tables can be avoided. Adjust the discharge system such that a slightly higher amount of lime is discharged from the firing shaft

Clogged burner lances

Temperature in upper part of the Adjust excess air correctly. burning zone too high

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8

Maintenance

8.1

In general

GENERAL INSTRUCTION & OPERATION Maintenance

The following provides basic information on how to do maintenance work essential to ensure optimum performance and trouble-free operation of the lime kiln. Detailed descriptions of the necessary maintenance work for each individual component can be found in Instruction Manual Book-2 Specific Data & Component Description. Maintenance intervals The listed maintenance intervals have been determined for the intended performance of the kiln as well as for the intended work and operating conditions. They are based on long-term experience and our first hand inspections at various plants. If regular inspection of the lime kiln show an increased level of wear, the operating person must adjust intervals as required by the actual constraints on the lime kiln and the indications of wear. If an irregularity cannot be removed by performing the steps described below, the manufacturer is to be notified immediately.

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8.2

GENERAL INSTRUCTION & OPERATION Maintenance

Safety WARNING Improperly performed maintenance work can lead to severe physical injury or damage to property. Any work related to upkeep and maintenance is to be carried out exclusively by qualified and authorized expert personnel.

When performing maintenance, make sure to observe the following: - Shut down the kiln and lock against restarting - Do not perform any work unless the kiln has been shut down. - Lock moving parts to prevent further motion. - Attach a well-visible sign warning of work in progress to the main switch and the access areas of the kiln (see figure).

Fig. 71

Sign warning of work in progress (typical)

WARNING Danger of injury! Any accidental start of the machine during maintenance or repairs may cause serious injury, permanent bodily impairment or death! Therefore: - Remove the key from the key switch and keep it out of reach of third parties by storing it in your own pocket until work has been completed. - Lock the main switch with a padlock to prevent the machine from restarting. Remove the key and keep it with you. - Inform the machine operator as well as the supervisor about the expected scope and duration of the maintenance work.

8.3

Lubricating instruction This information can be found in the documents listed under ‘Mandatory reference material’ at the beginning of this chapter.

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8.4

GENERAL INSTRUCTION & OPERATION Maintenance

Maintenance schedule NOTICE Adhere to the following inspection schedule to keep the kiln operational. If the employee entrusted with the inspection is incapable of performing the necessary inspection tasks, contact the manufacturer immediately and ask for training or have the inspection performed by the service staff of the manufacturer.

= = = =

○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

A-Check B-Check C-Check D-Check

Weekly

Section Component: Procedure

Monthly

Check list

Annually

8.4.1

ENTRY Note

Kiln housing & platforms >>> refer to instructions from supplier / manufacturer Emergency exit

○

First aid place

○

Skip hoist >>> refer to instructions from supplier / manufacturer ○

Visual inspection Δ

Breaks

● ○

Rails and wheels

●

Limit switches: function & position Ropes

Δ

Winch motor

Δ

○

● ● ●

Lubricate the lubricating points Visual inspection of the platform – Kiln hopper (any stones on the platform?)

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○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

= = = =

Weekly

A-Check B-Check C-Check D-Check

Monthly

Section Component: Procedure

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

ENTRY Note

Kiln hopper (type of kiln: RxP, RxS, FxP, FxS) >>> refer to instructions from supplier / manufacturer ○

Visual inspection Load cell (if applicable)

●

○

●

○

Vibration feeder (type of kiln: RxP, RxS, FxP, FxS) >>> refer to instructions from supplier / manufacturer Charge guiding: lost stones

○

Visual inspection Δ

Suspension: visual inspection

●

○

Reversible belt conveyor (type of kiln: RxP, RxS, FxP, FxS) >>> refer to instructions from supplier / manufacturer ○

Visual inspection Charge guiding: lost stones, fallen off the belt

●

○

Belt position: change of position in bidirectional operation

●

○

●

○

Scrapers: condition

▲

Motor

Δ

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Δ

●

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○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

= = = =

Weekly

A-Check B-Check C-Check D-Check

Monthly

Section Component: Procedure

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

ENTRY Note

Rotating bucket (type of kiln: RxP, RxS, FxP, FxS) >>> refer to instructions from supplier / manufacturer Visual inspection

○

Hydraulic system: tightness

●

Limit switches: function & position

●

○

Hydraulic cylinder: correct speed

●

○

●

○

●

Throttle valve & directional valve Rotating bucket: rotation

●

Lowering brake valves

●

Lubricate the lubricating points Δ

Motor

● ●

Load cell (if applicable)

○ ○

Visual inspection of the load cell (if applicable) Stone distributor (type of kiln: FxP, FxS) >>> refer to instructions from supplier / manufacturer Visual inspection

○

Hydraulic system: tightness

●

Hydraulic cylinder: correct speed

●

○

●

○

●

Throttle valve & directional valve Limit switches: function & position

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○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

= = = =

Weekly

A-Check B-Check C-Check D-Check

Monthly

Section Component: Procedure

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

ENTRY Note

Kiln shaft & Connecting channel >>> refer to instructions from supplier / manufacturer Surface temperature: measure and record

●

Tightness

●

Kiln doors: gaskets

▲

●

○

Poking holes: gaskets

▲

●

○

Ring channel: Clean (type of kiln: RxP, RxS, FxP, FxS)

●

Connecting channel: Clean

●

○

Shaft closing flap (type of kiln: RxP, RxS, FxP, FxS) >>> refer to instructions from supplier / manufacturer Visual inspection

○

Hydraulic system: tightness

●

Hydraulic cylinder: correct speed

●

○

Throttle valve & directional valve

●

○

●

○

Limit switches: function & position

●

Gaskets

▲

Δ

●

Lubricate the lubricating points

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= = = =

○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

A-Check B-Check C-Check D-Check

Weekly

Section Component: Procedure

Monthly

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

ENTRY Note

Level indicator >>> refer to instructions from supplier / manufacturer Visual inspection

○

Hydraulic system: tightness

●

Hydraulic cylinder: correct speed

●

○

Throttle valve & directional valve

●

○

●

Limit switches: function & position

●

Gaskets Rotating measuring transducer: signal test

●

Chain und Chain

●

Refractory lining >>> refer to instructions from supplier / manufacturer

Δ ●

Kiln shell: search for hot spots

○ ●

Refractory bricks in discharged lime ●

Kiln channels Burning-, pre-heating- & cooling zone: Condition

○

○

Suspended cylinder (type of kiln: RxS, FxS) >>> refer to instructions from supplier / manufacturer ○

Blower house: Accessibility & emergency lighting Visual inspection

●

○

Diesel-emergency blower: Fuel level in diesel tank, Antifreeze liquid

●

○

Batteries

●

Lubricate the lubricating points

●

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○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

= = = =

Weekly

A-Check B-Check C-Check D-Check

Monthly

Section Component: Procedure

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

●

○

ENTRY Note

Discharge table >>> refer to instructions from supplier / manufacturer Visual inspection

●

Hydraulic system: tightness Hydraulic cylinder: correct speed

●

○

Throttle valve & directional valve

●

○

●

Limit switches: function & position Gaskets

●

Lubricate the lubricating points

●

○

●

○

Discharge flap >>> refer to instructions from supplier / manufacturer Visual inspection

●

Hydraulic system: tightness Hydraulic cylinder: correct speed

●

○

Throttle valve & directional valve

●

○

●

Limit switches: function & position Gaskets

●

Lubricate the lubricating points

●

○

●

○

Start-up burner >>> refer to instructions from supplier / manufacturer Visual inspection

●

○

Gauges: operating pressure

●

Free flow of combustion air

●

Free flow of steam

● ●

Flame control

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○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

= = = =

Weekly

A-Check B-Check C-Check D-Check

Monthly

Section Component: Procedure

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

●

○

ENTRY Note

Blowers >>> refer to instructions from supplier / manufacturer Visual inspection ●

Blower: Condition & function

○ ●

Blower: Oil level

○

Motors

●

○

Filter

●

○

●

Sound absorbers

○ ●

Safety valve - & Check valve

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○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

= = = =

Weekly

A-Check B-Check C-Check D-Check

Monthly

Section Component: Procedure

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

●

○

●

○

ENTRY Note

Firing system: Solid fuel >>> refer to instructions from supplier / manufacturer ●

Leak test Dosing pump & fuel pump

Δ

Y- tube switch: Condition & function

●

○

Y-Splitter: Condition & function

●

○

Feeding shoe

●

○

Filter

●

○

Dome valves

●

○

Injector

●

○

●

Explosion door

●

Load cell (if applicable) Rotary dosing valve

●

Inert gas system

●

Valves: Condition & function

●

○

○ ●

Limit switches: Function & position

○

○

Inertgassystem >>> refer to instructions from supplier / manufacturer Manometer: Operating pressure

●

○

Thermometer: Operating temperature

●

○

Free flow

●

○

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○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Burner lances >>> refer to instructions from supplier / manufacturer

Δ

Length of lances

Δ

Shift tour

= = = =

Weekly

A-Check B-Check C-Check D-Check

Monthly

Section Component: Procedure

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

●

○

ENTRY Note

○

Waste gas temperature: modification (different lance length) Scaling and combustion of burner lances

●

○

Corrosion of lance protection boxes

●

○

Free flow of lance cooling air

●

Free flow of fuel

●

Reversal flap >>> refer to instructions from supplier / manufacturer ●

Visual inspection

○ ●

Hydraulic system: tightness Limit switches: function & position

●

○

Hydraulic cylinder: correct speed

●

○

●

Throttle valve & directional valve Lubricate the lubricating points

●

Gaskets

●

○

●

○

Relief flap >>> refer to instructions from supplier / manufacturer Visual inspection

●

Hydraulic system: tightness Limit switches: function & position

●

○

Hydraulic cylinder: correct speed

●

○

●

Throttle valve & directional valve Lubricate the lubricating points

●

Gaskets

●

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CALQUIPA S.A.C. 185 / 190

○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

= = = =

Weekly

A-Check B-Check C-Check D-Check

Monthly

Section Component: Procedure

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

●

○

●

○

●

○

●

○

ENTRY Note

Hydraulic system >>> refer to instructions from supplier / manufacturer Hydraulic unit Hydraulic oil: analysis

●

○

Hydraulic oil

Δ

○

Oil filter

▲

Δ

Valve rack Hydraulic cylinder

▲

Motor

Δ

Δ

●

Hydraulic: valve racks >>> refer to instructions from supplier / manufacturer ●

Throttle valve & directional valve Air blast unit >>> refer to instructions from supplier / manufacturer Visual inspection

●

○

Performance check (check for deposits in connecting channel)

●

○

Operational check (listen for pressure relief of the kiln)

●

○

Waste gas filter >>> refer to instructions from supplier / manufacturer ●

Visual inspection

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○ ● Δ ▲

Limited check (visual, sound, …) Full check: verify, measure, adjust Replace if required Replace: exchange, renew, overhaul

Shift tour

= = = =

Weekly

A-Check B-Check C-Check D-Check

Monthly

Section Component: Procedure

GENERAL INSTRUCTION & OPERATION Maintenance

Annually

IM

●

○

ENTRY Note

Fire protection >>> refer to instructions from supplier / manufacturer Inert gas circuit: gas storage (residual pressure) Readiness

●

○

●

○

●

Complete test run Trace heating system >>> refer to instructions from supplier / manufacturer Operating temperature Sensors & instrumentation >>> refer to instructions from supplier / manufacturer

Δ

Optical pyrometer

●

○

Optical pyrometer: Glass, cleaning

Δ

●

○

Optical pyrometer: Channel, cleaning

Δ

●

○

Thermocouples

Δ

●

○

Thermometer

Δ

●

○

Pressure gauge

Δ

●

○

Weighing devices

Δ

●

○

Volume readings

Δ

●

○

E = 0.90

Electric control cabinet, MCC >>> refer to instructions from supplier / manufacturer ●

○

Log data backup (Process history)

●

●

Emergency power supply: test run

●

Visual inspection Kiln operator, visual display >>> refer to instructions from supplier / manufacturer

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GENERAL INSTRUCTION & OPERATION Maintenance

NOTICE Changing the lances requires a great deal of experience. Contact the manufacturer for assistance when replacing the lances for the first time.

8.5

After maintenance After maintenance work, the following steps are to be carried out while adhere to safety regulations: - Check tightening of all screwed connections previously loosened. - Check that all previously removed safety devices, covers, and container lids have been re-installed properly. - Make sure that all tools, material, and other equipment used during maintenance have been removed from the working area. - Clean the working area and remove substances, such as liquids, process material, and the like, which may have escaped from the kiln. - Make sure that all safety measures of the plant are perfectly operational again.

WARNING Risk of personal injury during restart! Before re-operating the kiln, make sure that nobody is left inside the danger zone. There is a risk of death due to high temperatures and moving parts.

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9

GENERAL INSTRUCTION & OPERATION Index

Index

A

Hydraulic system ........................................62

Accidents....................................................30

I

ADMINISTRATOR, user level................... 101

Impurities....................................................38

B

Inbetriebnahme ..........................................81

Basic Technological Principles ...................37

Instrumentation...........................................76

Bulk density ................................................40

Intended use ..............................................23

Burner lances .............................................59

K

C

Kiln Pressure Test ......................................84

Calcination ........................................... 37, 43

L

Calorific values ...........................................52

Leakage Test .............................................84

Charging device .........................................60

Limestone...................................................37

Control system ...........................................69

Liquid fuels .................................................53

D

literature .....................................................37

Danger areas .............................................32

Local operation panel .................................74

Dangers .....................................................25

Lubricating instruction...............................176

Density .......................................................39

M

Design ........................................................56

Maintenance .............................................175

E

Maintenance schedule..............................177

Electric switchboard ...................................70

Malfunction ...............................................165

Emergency process stop ............................28

Mass flow ...................................................67

ENGINEERING, user level ....................... 101

Mechanical strength ...................................41

F

Mineral structure.........................................39

Failure ...................................................... 166

Mineralogical composition ..........................37

Filling ........................................................ 138

Modes of operation ...................................127

Formation of limestone ...............................37

N

Fuel ............................................................51

Noisy areas ................................................34

Functioning.................................................55

O

G

Operation ...................................................91

Gaseous fuels ............................................54

Operational procedures ............................137

Grain size ............................................. 39, 66

OPERATOR, user level ............................101

H

Operator’s log .............................................94

Heat flow ....................................................67

Overview area ............................................96

Heating-up................................................ 140

P

Heating-up process .................................. 139

Packaging ..................................................18

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GENERAL INSTRUCTION & OPERATION Index

Parameter ................................................102

Segregation ..............................................157

Parameter calculation ...............................135

Solid fuels.................................................. 53

Particle size ................................................40

Stop ..........................................................152

Personal safety equipment .........................24

Storage...................................................... 19

Porosity ......................................................39

T

Process pictures .......................................105

Temperature profile ................................... 68

R

Thermal decomposition ............................. 43

Reactivity....................................................47

Thermal dissociation.................................. 40

Refractory lining .........................................62

Transport ................................................... 17

Restart after failure ...................................169

Troubleshooting ........................................169

Restarting .................................................152

Two-shaft kiln ............................................ 58

Retention time ............................................48

U

Reversing and task sequences .................130

User level .................................................101

S

V

Safety ................................... 21, 91, 165, 176

Visualization system .................................. 95

Sandwich-method.....................................159

W

Screen layout .............................................96

Working area ............................................. 98

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