UOP4 MKII Manual - SL Extraction

SOLID/LIQUID EXTRACTION UNIT

Instruction Manual UOP4 MKII ISSUE 16 November 2010

Table of Contents Copyright and Trademarks ...................................................................................... 1 General Overview ....................................................................................................... 2 Equipment Diagrams................................................................................................... 3 Important Safety Information..................................................................................... 10 Introduction............................................................................................................ 10 General Safety Rules ............................................................................................ 10 The COSHH Regulations ...................................................................................... 14 Water Borne Hazards ............................................................................................ 15 Electrical Safety..................................................................................................... 15 Description ................................................................................................................ 17 Overview................................................................................................................ 17 Process Components ............................................................................................ 18 Console (Front Panel Components) ...................................................................... 21 Console (Rear Panel Components)....................................................................... 23 Console (Components on Underside) ................................................................... 24 Installation ................................................................................................................. 25 Advisory................................................................................................................. 25 Installation Requirements ...................................................................................... 25 Installation Process ............................................................................................... 26 Connection to Services.......................................................................................... 26 Using the Optional Educational Software and Data Logging Accessory ............... 28 Commissioning ...................................................................................................... 28 Electrical Wiring Diagram ...................................................................................... 30 Operation .................................................................................................................. 31 Operating the Software.......................................................................................... 31 Operating the Equipment....................................................................................... 41 Cleaning after use ................................................................................................. 49 Equipment Specifications.......................................................................................... 52 Overall Dimensions ............................................................................................... 52 ii

Table of Contents I/O Port Pin Connections ....................................................................................... 52 Environmental Conditions...................................................................................... 53 Routine Maintenance ................................................................................................ 55 Responsibility ........................................................................................................ 55 General.................................................................................................................. 55 Configuration of the PID Temperature Controllers ................................................ 56 Recalibration of the Thermocouple Conditioning Circuits...................................... 58 Recalibration of the Conductivity Conditioning Circuits ......................................... 59 RCD Test............................................................................................................... 60 Laboratory Teaching Exercises................................................................................. 61 Index to Exercises ................................................................................................. 61 Introduction and Background................................................................................. 61 Nomenclature ........................................................................................................ 62 Graphs of Concentration ....................................................................................... 64 Exercise A: Batch Extraction - Open Loop................................................................ 65 Exercise B: Batch Extraction - Closed Loop ............................................................. 69 Exercise C: Single Stage Continuous Extract ........................................................... 73 Exercise D: Two Stage Continuous Extraction ......................................................... 79 Exercise E: Three Stage Continuous Extraction ....................................................... 86 Project Work.............................................................................................................. 93 Contact Details for Further Information ..................................................................... 95

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Disclaimer This document and all the information contained within it is proprietary to Armfield Limited. This document must not be used for any purpose other than that for which it is supplied and its contents must not be reproduced, modified, adapted, published, translated or disclosed to any third party, in whole or in part, without the prior written permission of Armfield Limited. Should you have any queries or comments, please contact the Armfield Customer Support helpdesk (Monday to Friday: 0800 – 1800 GMT). Contact details are as follows: United Kingdom

International

(0) 1425 478781 (calls charged at local rate)

+44 (0) 1425 478781 (international rates apply)

Email: [email protected] Fax: +44 (0) 1425 470916

Copyright and Trademarks Copyright © 2009 Armfield Limited. All rights reserved. Any technical documentation made available by Armfield Limited is the copyright work of Armfield Limited and wholly owned by Armfield Limited. Brands and product names mentioned in this manual may be trademarks or registered trademarks of their respective companies and are hereby acknowledged.

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General Overview The extraction (leaching) of a substance from a solid material with the aid of a liquid is a common process in chemical engineering which can be applied to appropriate biological, inorganic and organic substances. A familiar activity which illustrates this process is the making of tea or coffee, where hot water is used to perform the extraction from tea leaves or coffee beans. Other examples are the extraction of sugar from sugar beet using hot water and the extraction of oils from seeds using organic solvents such as hexane, acetone or ether. For the solid/liquid extraction process to be appropriate, the substance to be extracted (tea) must be soluble while the solid phase (tea leaves) must be insoluble in the chosen solvent (hot water). The appropriate solvent is introduced to the solid material and the two remain in contact while the soluble component dissolves into the solvent. The solvent containing the dissolved substance (the miscella) is then drained from the insoluble solid. This is the basis of all solid/liquid extraction processes. Further processing may be required to recover the extracted substance from the solvent. Before performing solid/liquid extraction the solid material must be prepared by crushing, grinding or cutting, as appropriate, to allow adequate contact between the solvent and the soluble component. The amount of preparation will depend on the amount and distribution of the soluble component within the solid and the nature of the solid (how easily diffusion can occur). Numerous different types of solid/liquid extractors may be employed to perform the basic task of introducing the solvent to the material to be extracted. The extraction process may involve batch operation (fixed-bed) with the addition of open loop or closed loop circulation of the solvent. Alternatively extraction may be a continuous operation (moving-bed) with single or multi-stage processing involving co-current flow or counter current flow of the solvent and the soluble material to be extracted. In large scale industrial solid/liquid extraction systems economic factors frequently lead to the use of the more sophisticated multi-stage counter current flow systems due to their high extraction efficiency. The Armfield UOP4 MkII is designed to demonstrate a simplified version of the moving-bed leaching process used by many industrial solid/liquid extraction systems. The process used is a continuous multi-stage process, which gives counter current flow of the solvent and the solid phase. A batch extraction vessel is also incorporated to allow demonstration of fixed-bed leaching with either open or closed loop circulation of the solvent. The recommended process for the UOP4 MkII is the extraction of Potassium Bicarbonate from a solid carrier of porous polymer pellets using water as the solvent.

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Equipment Diagrams

Figure 1: Front View of UOP4 MKII Solid/Liquid Extraction Unit

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Armfield Instruction Manual

Figure 2: Side View of UOP4 MKII Solid/Liquid Extraction Unit

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Equipment Diagrams

Figure 3: UOP4 MKII Schematic Diagram Showing 3 Stage Process

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Armfield Instruction Manual

Figure 4: UOP4 MkII Console - Front View

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Equipment Diagrams

Figure 5: UOP4 MkII Console - Rear View

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Armfield Instruction Manual

Figure 6: PCB Connections

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Equipment Diagrams

Figure 7: Location of Temperature Calibration Potentiometers on PCB

Figure 8: Location of Conductivity Calibration Potentiometers on Conductivity Measurement PCB

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Important Safety Information Introduction All practical work areas and laboratories should be covered by local safety regulations which must be followed at all times. It is the responsibility of the owner to ensure that all users are made aware of relevant local regulations, and that the apparatus is operated in accordance with those regulations. If requested then Armfield can supply a typical set of standard laboratory safety rules, but these are guidelines only and should be modified as required. Supervision of users should be provided whenever appropriate. Your UOP4 MKII Solid/Liquid Extraction Unit has been designed to be safe in use when installed, operated and maintained in accordance with the instructions in this manual. As with any piece of sophisticated equipment, dangers exist if the equipment is misused, mishandled or badly maintained. Before proceeding to install, commission or operate the equipment described in this instruction manual we wish to alert you to potential hazards so that they may be avoided. Although designed for safe operation, any laboratory equipment may involve processes or procedures which are potentially hazardous. The major potential hazards associated with this particular equipment are listed below. 

INJURY THROUGH MISUSE



INJURY FROM ELECTRIC SHOCK



INJURY FROM ROTATING COMPONENTS

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IRRITATION FROM DUST WHEN HANDLING DRY MATERIALS

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BURNS FROM COMPONENTS AT HIGH TEMPERATURES

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INJURY FROM INCORRECT HANDLING

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DAMAGE TO CLOTHING

Accidents can be avoided provided that equipment is regularly maintained and staff and students are made aware of potential hazards. A list of general safety rules is included in this manual, to assist staff and students in this regard. The list is not intended to be fully comprehensive but for guidance only. Please refer to the notes overleaf regarding the Control of Substances Hazardous to Health Regulations.

General Safety Rules 1. Follow Relevant Instructions a. Before attempting to install, commission or operate equipment, all relevant suppliers’/manufacturers’ instructions and local regulations should be understood and implemented.

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Important Safety Information b. It is irresponsible and dangerous to misuse equipment or ignore instructions, regulations or warnings. c. Do not exceed specified maximum operating conditions (eg. temperature, pressure, speed etc). 2. Installation a. Use lifting tackle where possible to install heavy equipment. Where manual lifting is necessary beware of strained backs and crushed toes. Get help from an assistant if necessary. Wear safety shoes where appropriate. b. Extreme care should be exercised to avoid damage to the equipment during handling and unpacking. When using slings to lift equipment, ensure that the slings are attached to structural framework and do not foul adjacent pipework, glassware etc. When using fork lift trucks, position the forks beneath structural framework ensuring that the forks do not foul adjacent pipework, glassware etc. Damage may go unseen during commissioning creating a potential hazard to subsequent operators. c. Where special foundations are required follow the instructions provided and do not improvise. Locate heavy equipment at low level. d. Equipment involving inflammable or corrosive liquids should be sited in a containment area or bund with a capacity 50% greater than the maximum equipment contents. e. Ensure that all services are compatible with the equipment and that independent isolators are always provided and labelled. Use reliable connections in all instances, do not improvise. f.

Ensure that all equipment is reliably earthed and connected to an electrical supply at the correct voltage. The electrical supply must incorporate a Residual Current Device (RCD) (alternatively called an Earth Leakage Circuit Breaker - ELCB) to protect the operator from severe electric shock in the event of misuse or accident.

g. Potential hazards should always be the first consideration when deciding on a suitable location for equipment. Leave sufficient space between equipment and between walls and equipment. 3. Commissioning a. Ensure that equipment is commissioned and checked by a competent member of staff before permitting students to operate it. 4. Operation a. Ensure that students are fully aware of the potential hazards when operating equipment. b. Students should be supervised by a competent member of staff at all times when in the laboratory. No one should operate equipment alone. Do not leave equipment running unattended. c. Do not allow students to derive their own experimental procedures unless they are competent to do so. 11

Armfield Instruction Manual d. Serious injury can result from touching apparently stationary equipment when using a stroboscope to `freeze´ rotary motion. 5. Maintenance a. Badly maintained equipment is a potential hazard. Ensure that a competent member of staff is responsible for organising maintenance and repairs on a planned basis. b. Do not permit faulty equipment to be operated. Ensure that repairs are carried out competently and checked before students are permitted to operate the equipment. 6. Using Electricity a. At least once each month, check that ELCBs (RCCBs) are operating correctly by pressing the TEST button. The circuit breaker must trip when the button is pressed (failure to trip means that the operator is not protected and a repair must be effected by a competent electrician before the equipment or electrical supply is used). b. Electricity is the commonest cause of accidents in the laboratory. Ensure that all members of staff and students respect it. c. Ensure that the electrical supply has been disconnected from the equipment before attempting repairs or adjustments. d. Water and electricity are not compatible and can cause serious injury if they come into contact. Never operate portable electric appliances adjacent to equipment involving water unless some form of constraint or barrier is incorporated to prevent accidental contact. e. Always disconnect equipment from the electrical supply when not in use. 7. Avoiding fires or explosion a. Ensure that the laboratory is provided with adequate fire extinguishers appropriate to the potential hazards. b. Where inflammable liquids are used, smoking must be forbidden. Notices should be displayed to enforce this. c. Beware since fine powders or dust can spontaneously ignite under certain conditions. Empty vessels having contained inflammable liquids can contain vapour and explode if ignited. d. Bulk quantities of inflammable liquids should be stored outside the laboratory in accordance with local regulations. e. Storage tanks on equipment should not be overfilled. All spillages should be immediately cleaned up, carefully disposing of any contaminated cloths etc. Beware of slippery floors. f.

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When liquids giving off inflammable vapours are handled in the laboratory, the area should be ventilated by an ex-proof extraction system. Vents on the equipment should be connected to the extraction system.

Important Safety Information g. Students should not be allowed to prepare mixtures for analysis or other purpose without competent supervision. 8. Handling poisons, corrosive or toxic materials a. Certain liquids essential to the operation of equipment, for example mercury, are poisonous or can give off poisonous vapours. Wear appropriate protective clothing when handling such substances. Clean up any spillage immediately and ventilate areas thoroughly using extraction equipment. Beware of slippery floors. b. Do not allow food to be brought into or consumed in the laboratory. Never use chemical beakers as drinking vessels. c. Where poisonous vapours are involved, smoking must be forbidden. Notices should be displayed to enforce this. d. Poisons and very toxic materials must be kept in a locked cupboard or store and checked regularly. Use of such substances should be supervised. e. When diluting concentrated acids and alkalis, the acid or alkali should be added slowly to water while stirring. The reverse should never be attempted. 9. Avoiding cuts and burns a. Take care when handling sharp edged components. Do not exert undue force on glass or fragile items. b. Hot surfaces cannot, in most cases, be totally shielded and can produce severe burns even when not `visibly hot´. Use common sense and think which parts of the equipment are likely to be hot. 10. Eye protection a. Goggles must be worn whenever there is a risk to the eyes. Risk may arise from powders, liquid splashes, vapours or splinters. Beware of debris from fast moving air streams. Alkaline solutions are particularly dangerous to the eyes. b. Never look directly at a strong source of light such as a laser or Xenon arc lamp. Ensure that equipment using such a source is positioned so that passers-by cannot accidentally view the source or reflected ray. c. Facilities for eye irrigation should always be available. 11. Ear protection a. Ear protectors must be worn when operating noisy equipment. 12. Clothing a. Suitable clothing should be worn in the laboratory. Loose garments can cause serious injury if caught in rotating machinery. Ties, rings on fingers etc. should be removed in these situations. b. Additional protective clothing should be available for all members of staff and students as appropriate. 13

Armfield Instruction Manual 13. Guards and safety devices a. Guards and safety devices are installed on equipment to protect the operator. The equipment must not be operated with such devices removed. b. Safety valves, cut-outs or other safety devices will have been set to protect the equipment. Interference with these devices may create a potential hazard. c. It is not possible to guard the operator against all contingencies. Use common sense at all times when in the laboratory. d. Before starting a rotating machine, make sure staff are aware how to stop it in an emergency. e. Ensure that speed control devices are always set at zero before starting equipment. 14. First aid a. If an accident does occur in the laboratory it is essential that first aid equipment is available and that the supervisor knows how to use it. b. A notice giving details of a proficient first-aider should be prominently displayed. c. A `short list´ of the antidotes for the chemicals used in a particular laboratory should be prominently displayed.

The COSHH Regulations The Control of Substances Hazardous to Health Regulations (1988) The COSHH regulations impose a duty on employers to protect employees and others from substances used at work which may be hazardous to health. The regulations require you to make an assessment of all operations which are liable to expose any person to hazardous solids, liquids, dusts, vapours, gases or microorganisms. You are also required to introduce suitable procedures for handling these substances and keep appropriate records. Since the equipment supplied by Armfield Limited may involve the use of substances which can be hazardous (for example, cleaning fluids used for maintenance or chemicals used for particular demonstrations) it is essential that the laboratory supervisor or some other person in authority is responsible for implementing the COSHH regulations. Part of the above regulations is to ensure that the relevant Health and Safety Data Sheets are available for all hazardous substances used in the laboratory. Any person using a hazardous substance must be informed of the following: Physical data about the substance Any hazard from fire or explosion Any hazard to health Appropriate First Aid treatment

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Important Safety Information Any hazard from reaction with other substances How to clean/dispose of spillage Appropriate protective measures Appropriate storage and handling Although these regulations may not be applicable in your country, it is strongly recommended that a similar approach be adopted for the protection of the students operating the equipment. Local regulations must also be considered.

Water Borne Hazards The equipment described in this instruction manual involves the use of water, which under certain conditions can create a health hazard due to infection by harmful micro-organisms. For example, the microscopic bacterium called Legionella pneumophila will feed on any scale, rust, algae or sludge in water and will breed rapidly if the temperature of water is between 20 and 45°C. Any water containing this bacterium which is sprayed or splashed creating air-borne droplets can produce a form of pneumonia called Legionnaires Disease which is potentially fatal. Legionella is not the only harmful micro-organism which can infect water, but it serves as a useful example of the need for cleanliness. Under the COSHH regulations, the following precautions must be observed: 

Any water contained within the product must not be allowed to stagnate, ie. the water must be changed regularly.



Any rust, sludge, scale or algae on which micro-organisms can feed must be removed regularly, i.e. the equipment must be cleaned regularly.



Where practicable the water should be maintained at a temperature below 20°C. If this is not practicable then the water should be disinfected if it is safe and appropriate to do so. Note that other hazards may exist in the handling of biocides used to disinfect the water.



A scheme should be prepared for preventing or controlling the risk incorporating all of the actions listed above.

Further details on preventing infection are contained in the publication “The Control of Legionellosis including Legionnaires Disease” - Health and Safety Series booklet HS (G) 70.

Electrical Safety The equipment described in this Instruction Manual operates from a mains voltage electrical supply. It must be connected to a supply of the same frequency and voltage as marked on the equipment or the mains lead. If in doubt, consult a qualified electrician or contact Armfield. The equipment must not be operated with any of the panels removed. To give increased operator protection, the unit incorporates a Residual Current Device (RCD), alternatively called an Earth Leakage Circuit Breaker, as an integral 15

Armfield Instruction Manual part of this equipment. If through misuse or accident the equipment becomes electrically dangerous, the RCD will switch off the electrical supply and reduce the severity of any electric shock received by an operator to a level which, under normal circumstances, will not cause injury to that person. At least once each month, check that the RCD is operating correctly by pressing the TEST button. The circuit breaker MUST trip when the button is pressed. Failure to trip means that the operator is not protected and the equipment must be checked and repaired by a competent electrician before it is used.

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Description Where necessary, refer to the drawings in the Equipment Diagrams section.

Overview The heart of the solid/liquid extraction system is a continuously rotating extraction cell divided into compartments. The raw material is fed into these compartments from the input hopper using a screw feeder mechanism. The material is then passed under three solvent sprinkler bars, one for each stage of the process, and the dissolved product captured in the three collection troughs. Pumps are provided at each stage to pump the product from the collection trough of one stage to the sprinkler of the next stage. At the end of its cycle, the spent carrier material is dropped into a collection tank aided by water spraying from a nozzle. The system is configured as a three stage, counter current flow process, but may also be configured as a one or two stage process for teaching purposes. Full temperature control is provided at each stage of the process using the three integrated PID controllers and related heating elements. Direct control is also provided over the product feed rate, the cell rotation speed and the inter-stage pump speeds. In addition to the rotary cell, an independent vessel is provided which allows batch extractions to be performed. The unit is fully instrumented with each stage of the process equipped with sensors, giving a temperature and a milli-volt conductivity probe output. When using the standard water / Potassium Bicarbonate system, the sensor readings can be related to the percentage weight of Potassium Bicarbonate in the solution using experimental data. All temperatures and voltage outputs from the conductivity probes, together with the feed, extractor cell and individual pump rates can also be displayed on a computer using the optional data logging package. Using this package it is also possible to display and log the product concentration (when using the recommended materials). The equipment is designed to teach all relevant aspects of solid/liquid extraction in a simple and safe manner. It does not require the use of toxic, volatile or flammable solvents, as it is designed to use water or water based solvents. This allows the process to be made fully visible to students, allowing them to observe and understand the details of the operation at every stage. There is no need for expensive solvent recovery equipment such as a distillation column. The recommended process for the UOP4 MkII is the extraction of Potassium Bicarbonate (Potassium Hydrogencarbonate, chemical symbol KHCO 3 ) from a solid carrier of porous polymer pellets (microporous Polyamide 6-pellets) using water as the solvent. This combination of a non-toxic salt with water and an inert solid gives a safe demonstration of the process and a simple measurement of the conductivity and temperature at each stage in the process allows the changing concentration (percentage weight) of the salt in the water to be determined. A quantity of porous polymer pellets is supplied with the equipment. These plastic pellets are used as the carrier for convenience and avoid dust, grit etc that could cause operational problems. The plastic pellets can be reclaimed and reused. The process can be monitored in real time using the displays on the console, which show the conductivity probe output and temperature of the solvent at each of the 17

Armfield Instruction Manual stages. Using experimental data these values can be related to the percentage weight of Potassium Bicarbonate in the solution. Alternatively the optional UOP4MkII303IFD Data logging and Educational Software Accessory may be used to automatically log the measurements, perform the necessary calculations and present the results in a real time graph. If the UOP4 MkII is used with any other extractable material the relationships between conductivity probe output, percentage weight and temperature will need to be investigated by the user (refer to project work in the UOP4 MkII Teaching Manual for further information). It may be possible to use other solid materials, but these would need to be evaluated in conjunction with the rotating cell and the feed mechanism. Materials must not be used that generate dust as this could settle in the pipework causing blockages. Figure 3 the schematic diagram shows the various stages of the process with the solids and solvent (water) flowing counter-currently. In reality the solids rotate in a circular path but for simplicity, the compartments of the rotor and the solvent collecting troughs are shown in a straight line in the diagram.

Process Components All the numerical references in this section relate to the equipment diagrams. The letters a, b and c associated with each numerical reference refer to the three stages of the process a = First stage, b= Second stage and c= Third/Final stage. 1. Framework The equipment is fitted into a welded steel framework constructed from circular section members and supported on adjustable feet. 2. Console The metal console housing contains the majority of the electrical components and electronic circuit boards. The rear panel incorporates the various protection devices. The front panel incorporates the three PID controllers, the measurement display and various control knobs and switches (see Description of Console for further details). 3. Pumps (3a, 3b, 3c) The three solvent stages are supplied by three peristaltic pumps, which have a maximum capacity of approximately 13 l/hr. The rotary controls for varying the speed of the pumps are on the front panel of the console. 4. Solvent Heaters (4a, 4b, 4c) Each of the three solvent stages has a separate solvent heater which is controlled using a PID controller on the console. The heater consists of a cartridge element which is enclosed in a concentric tubular jacket through which the solvent is circulated. The cartridge element is protected from over temperature by a thermocouple which senses the internal temperature of the element and a circuit which cuts the power if the temperature exceeds a preset value, when this happens the over-temperature indicator on the console flashes. The over-temperature protection automatically resets when the cartridge element cools down. 5. Conductivity Probes C1, C2, C3, C4 and Temperature Sensors T1, T2, T3, T4 18

Description At each of the three stages where the solvent is being fed into the rotor the concentration of the extracted Potassium Bicarbonate in the solvent is monitored using a temperature sensor and a flow-through conductivity probe. The temperature sensor is fitted in a quick release fitting which is mounted on the top of the solvent heater. The glass conductivity probe on each of the stages is positioned down stream of the temperature sensor and is connected to the quick release fitting via a section of flexible tubing. An additional temperature sensor T4 and conductivity probe C4 are incorporated at the point where the final miscella exits the process. Temperatures T1, T2 & T3 are indicated on the appropriate PID controller. Temperature T4 and conductivities C1, C2, C3 & C4 are displayed on the panel meter via a selector switch. 6. Solvent Sprinkler Bars (6a, 6b, 6c) The solvent is delivered on to the top of the moving bed of solids through three solvent sprinkler bars. The three sprinkler bars are positioned above the three solvent collecting troughs and represent the three stages of the process. The sprinkler bars are removable from the extraction cell to allow them to be cleaned. A hexagon adjuster (Allen screw) on the top of the hub above each bar clamps the bar in place. 7. Extraction Cell The function of the extraction cell is to transport the solids, which are being processed through the three solvent stages and to discharge the spent solids into the extracted solids tank. The base of the extraction cell supports the rotor that is driven by a geared motor located in the central hub. A clutch fitted between the motor and the rotor protects the motor/gearbox if the rotor is moved by hand or solid material jams between the rotor and the base. The rotor is divided into compartments by vertical baffles that sweep the solid material along as it rotates. The base incorporates a perforated stainless steel mesh, directly below the rotor, to allow the solvent that has percolated through the solid material being processed to drain into the solvent collection troughs below. The speed of the rotor can be varied from zero up to approximately four revolutions per hour using the rotary speed control on the console. The compartments of the rotor should be filled to approximately between one-third and half height by the feeder during normal operation. The base of the extraction cell is mounted at three points to allow the whole unit to be removed from the framework, if necessary. However, normal cleaning can be carried out with the base retained in the frame. Two clamp knobs on topof the central hub can be released, allowing the hub / rotor assembly to be removed from the base. It will be necessary to remove the Feeder and any flexible tubing / connecting leads before removing the hub / rotor. An aperture in the base of the extraction cell allows spent solid carrier to be discharged into the extracted solids tank underneath. A spray nozzle mounted above the rotor assists the discharge by washing the solids from the rotor. The spray nozzle is adjustable in height and a pressure regulating valve mounted at the rear of the extraction cell allows the spray pattern to be varied. These 19

Armfield Instruction Manual should be adjusted in combination to wash the spent solids into the extracted solids tank without spraying excess water outside of the rotor. 8. Solvent Collection Troughs (8a, 8b, 8c) As the solvent drains down through the stainless steel mesh it is collected in three troughs which correspond to the three solvent stages. Once the fresh solvent from the sprinkler bar in stage 1 has found its way into the first trough it is pumped to the sprinkler bar of the second stage. Similarly, miscella draining into the trough of the second stage is pumped to the sprinkler bar of the third stage. Final miscella draining into the trough of the third stage is allowed to flow into the final miscella tank by gravity. Each of the three troughs incorporates a vent through the sidewall to ensure consistent flow through the stainless steel mesh. In operation, the liquid level inside each trough must not be allowed to cover the elbow on the end of the vent tube inside the trough. 9. Filters (9a, 9b, 9c) Filters are incorporated at the outlet from each of the solvent collection troughs to prevent any solid particles from reaching the pumps, heaters or instrumentation. It may be necessary to clean these filters after use to remove any contamination. The correct procedure is described in the Routine Maintenance section of this Product Manual. 10. Material Hopper and Feeder. The solid material, which is to be extracted from in the process, is metered into the compartments of the rotor using a spiral type conveyor. The depth of the solids in the rotor can be controlled by adjusting the relative speeds of the feeder and/or the rotor using the rotary controls on the front of the console. It will be necessary to top up the hopper at regular intervals with fresh solid material which has been suitably prepared. Preparation of the material is described in the Operation section. 11. Fresh Solvent Tank The fresh solvent (usually de-mineralised water) is stored in this tank. During long runs it will be necessary to top-up this tank with de-mineralised water to prevent the system from running dry. It is suggested that de-mineralised water be used since hardness in tap water may form precipitates and salts in the tap water may affect the conductivity measurements. 12. Extracted Solids Tank The spent solids, having been leached of the soluble component, are continuously discharged from the extraction cell as each compartment passes an aperture in the base below the rotor. The solids, still wet with solvent, are washed into the extracted solids tank using a spray of water. A connector with integral filter, in the base of the tank, allows the water to flow to drain continuously while retaining the solids inside the tank. 13. Final Miscella Tank

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Description The liquid exiting the extraction process is called the final miscella. This is solvent with the extracted material dissolved in it. The final miscella is collected in the final miscella tank. It will be necessary to empty this tank periodically. 14. Batch Vessel A clear acrylic batch vessel mounted on the support frame allows solid/liquid extraction to be carried out on a fixed batch of material. The batch of material is placed in a cloth bag that is supplied with the equipment. The bag is located inside the batch vessel. Quick release connections at the top and bottom of the vessel allow appropriate components in the system to be incorporated to allow the demonstration of fixed-bed leaching with either open or closed loop circulation of the solvent. In normal operation the solvent enters at the bottom and flows upward through the vessel. A bypass valve at the bottom allows solvent to be recirculated without passing through the vessel (used to allow the temperature of the solvent to stabilise prior to extraction taking place). The batch vessel also allows samples of different materials to be tested where the material cannot be passed through the feeder and rotor arrangement. Refer to the Operation section for further information.

Console (Front Panel Components) All the references in this section relate to Figure 4 & 5 in the equipment diagrams. 15. Mains On/Off Switch This switch is the on/off switch for all functions in the console and should always be in the off position when the equipment is not in use. Before switching the console on it is important to make sure that the three heater switches are in the off position. 16. Feeder Speed Control and On/Off Switch. This rotary potentiometer adjusts the speed of the Spiral feeder and is used to vary the rate at which the material to be extracted is fed into the extraction cell. An On/Off switch is provided to start and stop the feeder without the need to change the speed setting. 17. Rotor Speed Control and On/Off Switch. This rotary potentiometer adjusts the speed of the rotor. Varying the rotor speed will have the effect of changing the time that each compartment spends under each sprinkler bar and the time under the material feeder which fills the compartments. An On/Off switch is provided to start and stop the rotor drive without the need to change the speed setting. 18. Temperature/Conductivity Display and Selector Switch This multifunction display can show either the reading of the temperature sensor at stage four (T4 final miscella out) or any one of the four conductivity probe readings (C1, C2, C3 and C4 in mV) as selected on the rotary switch. Note: Temperatures T1, T2 & T3 are indicted continuously on the appropriate PID controller. 19. Peristaltic Pump Speed Controls (19a, 19b, 19c) 21

Armfield Instruction Manual These three rotary potentiometers adjust the rotational speed and therefore the flow rate of the three peristaltic pumps. In operation, the three speeds will need to be adjusted so that there is a constant flow of liquid from one stage to the next without any of the stages running dry. 20. Heater On/Off Switches (20a, 20b, 20c) These switches allow the individual solvent stage heaters to be switched off when not required. Although the heaters are protected from overheating, they should be switched off before the console is switched on and whenever there is no fluid flow through the heaters. 21. Heater OVER TEMP indicators (21a, 21b, 21c) The indicator operates when the temperature of the heater has exceeded the upper level of the normal temperature range, this can happen when the flow of liquid in the heater is intermittent or when the heater is switched on and the solvent pump is switched off. When the indicator flashes the power to the heater will be cut until the system detects that the temperature has declined whereupon the system will automatically reset and the indicator will go out. To prevent the heater from going into over temp mode it is important to make sure that all of the heaters are switched off before turning on the console. The heaters should only be turned on when there is a constant flow of liquid through the heaters (for more details see Safe Operation). 22. PID Temperature Controllers (22a, 22b, 22c)

PID Controller

The PID controller has three keys that are used for adjusting the desired temperature set point and for altering the configuration of the controller. The configuration of each controller is set before delivery and should not require adjustment. If for any reason, the user needs to restore the configuration or wishes to alter it, the procedure and default settings are listed in the Routine Maintenance section of this manual. During normal operation the controller will display the process temperature (the temperature of the solvent leaving the appropriate heater, measured by the thermocouple located at the top of the heater). When power is supplied to the heater, the control output indicator, located above and to the left of the digital display on the PID controller, is illuminated. 22

Description To check the current set point: Press either the increase key

or decrease key

briefly.

The display will automatically return to the process temperature. To change the current set point: Press either the increase key point will be displayed.

or decrease key

Press and hold the increase or decrease required value of the digit is displayed.

briefly. The current set

key as required until the

The display will automatically return to the process temperature. Note: For optimum control of the temperatures within the process, without excessive overshoot, the setpoint of each controller should be set to ambient temperature when the equipment is first switched on with water flowing. Adjustment to the required setpoint during operation will then give smooth control without excessive overshoot. Similarly it is suggested that the temperature of stage 1 should be allowed to stabilise before increasing the setpoint of stage 2 and the temperature of stage 2 should be allowed to stabilise before increasing the setpoint of stage 3.

Console (Rear Panel Components) All the references in this section relate to Figure 4 & 5 in the equipment diagrams. 23. Residual Current Device If through misuse or accident the equipment becomes electrically dangerous the RCD will switch off the electrical supply and reduce the severity of any electric shock received by an operator to a level which, under normal circumstances, will not cause injury to that person. The RCD is alternatively called a Residual Current Circuit Breaker or RCCB. Refer to the Important Safety Information. 24. Circuit Breakers (a, b, c & d) There are four circuit breakers mounted on the rear of the console which protect the electrical circuits within the console from excess current flow, as follows: a. HEAT heaters.

6 Amp breaker to protect the mains supply to the

b. DC

4 Amp breaker to protect the DC power supply.

c. O/P

1 Amp breaker to protect the mains output socket

d. CONTROL 1 Amp thermal breaker to protect the mains supply to the PID controllers (push to reset). 23

Armfield Instruction Manual 25. Mains Output Socket The socket marked OUTPUT can be used to provide mains power at line voltage to any additional instrumentation used with the equipment. This socket is used to power the optional Armfield interface device IFD3 which is supplied with the Educational Software and Data Logging Accessory UOP4MkII-303IFD. The output current is limited to 1 Amp by a circuit breaker (24c). 26. Mains Input Socket This socket is used to connect the console to the mains electrical supply using the flexible mains lead supplied with the equipment. Ensure that the label fixed above the socket matches the voltage and frequency of the mains electrical supply before connecting the lead to the supply.

Console (Components on Underside) 27. I/O Port Socket The data from the temperature sensors, conductivity probes and speed settings for the pumps, feeder and rotor can be logged on a computer with the aid of an Armfield interface device. The UOP4 MkII is linked to the interface device using a ribbon cable that is plugged into the I/O Port socket on the underside of the console. The ribbon cable / interface device is supplied as part of the UOP4MkII-303IFD Educational Software and Data Logging Accessory. 28. Feeder connector A jack socket on the underside of the console allows the feeder to be disconnected from the console when it is necessary to remove it for cleaning. 29. Extraction cell connector A jack socket on the underside of the console allows the extraction cell to be disconnected from the console when it is necessary to remove the hub of the extraction cell for cleaning.

24

Installation Advisory Before operating the equipment, it must be unpacked, assembled and installed as described in the steps that follow. Safe use of the equipment depends on following the correct installation procedure.

Installation Requirements Electromagnetic Compatibility This apparatus is classified as Education and Training Equipment under the Electromagnetic Compatibility (Amendment) Regulations 1994. Use of the apparatus outside the classroom or similar such place invalidates the conformity with the protection requirements of the Electromagnetic Compatibility Directive (89/336/EEC) and could lead to prosecution.

Facilities Required Installation may be completed using a basic tool kit. The UOP4 MkII is designed for floor standing on a firm, level floor. When choosing a location for the equipment, the need to gain access to items such as the solvent tank for filling and the waste solids hopper for emptying will need to be taken into account. Access to all four sides of the equipment should be allowed. The unit requires connection to a mains electrical supply, a continuous supply of cold water and connection to a floor drain.

Mains Electrical Supply The equipment requires connection to a single phase fused electrical supply. Four metres of cable is supplied with the equipment, terminated with a plug to suit the mains input connector on the rear panel of the console. Three versions are available: UOP4 MkII-A 220/240V/1ph/50Hz @ 13 Amps UOP4 MkII-B 120V/1ph/60Hz @ 15 Amps UOP4 MkII-G 220/240V/1ph/60Hz @13 Amps

Cold Water Supply For reliable discharge of the spent solid carrier, a permanent connection to a cold water supply will be required. The supply should be connected to the inlet on the pressure regulator using ½” / 12.7 mm ID hose (not supplied by Armfield). A source of de-ionised water will also be required for preparing the salt solutions and for use as the solvent when performing solid/liquid extraction.

Laboratory Drain A suitable floor drain will be required to dispose of water from the equipment during operation. The outlet in the base of the extracted solids tank should be connected to the drain using ½” / 12.7 mm ID hose (not supplied by Armfield). Note that water drains from the tank under gravity and the drain connection must not therefore be restricted.

25

Armfield Instruction Manual

Installation Process All numerical references relate to the equipment diagrams. The UOP4 MkII Solid/Liquid Extraction Unit is supplied fully assembled. The following checks should be made to ensure that all electrical and fluid connections are intact and the equipment is ready for commissioning following shipping and unpacking. 1. Ensure that all packaging has been removed, especially from the rotor of the extraction cell (7) and the hopper/spiral feeder (10). 2. Connect the electrical mains lead supplied to the mains input socket (26) on the rear of the console but do not connect it to the electrical supply at this point. 3. Check that DC supply lead from hub of extraction cell is connected to socket on underside of console. Check that DC supply lead from motor on feeder is connected to socket on underside of console. 4. Check that the system is connected as shown in Figures 1 and 3. When correctly connected, fluid from the fresh solvent tank (11) should flow in the following sequence: First stage pump (3a on right-hand side) to first stage heater (4a) to first stage sprinkler bar (6a furthest anticlockwise). First stage solvent collection trough (8a) via filter (9a) to second stage pump (3b middle) to second stage heater (4b) to second stage sprinkler bar (6b middle). Second stage solvent collection trough (8b) via filter (9b) to third stage pump (3c left-hand side) to third stage heater (4c) to third stage sprinkler bar (6c furthest clockwise). Third stage solvent collection trough (8c) via filter (9c) then conductivity electrode C4 and temperature sensor T4 to overflow into final miscella tank (13). 5. Place the solid carrier (porous polymer pellets) and the filling tube/batch sample cloth, supplied with the equipment, in a safe location ready for use. The equipment is ready for connection to the appropriate services followed by commissioning. See Connection to Services and Commissioning.

Connection to Services Electrical Supply for Version UOP4 MKII-A Before connecting the electrical supply ensure that the RCD/RCCB (23) and all miniature circuit breakers (24a, 24b, 24c) are in the off (down position). Also ensure that all rotary controls are set to minimum and all switches are set to off on the front of the console. The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 220/240V, 50Hz. Check that the

26

Installation voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW

-

EARTH

BROWN

-

LIVE (HOT)

BLUE

-

NEUTRAL

Fuse Rating

-

13 AMP

Electrical Supply for Version UOP4 MKII-B Before connecting the electrical supply ensure that the RCD/RCCB (23) and all miniature circuit breakers (24 a,b,c) are in the off (down position). Also ensure that all rotary controls are set to minimum and all switches are set to off on the front of the console. The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 120V, 60Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW

-

EARTH

BROWN

-

LIVE (HOT)

BLUE

-

NEUTRAL

Fuse Rating

-

15 AMP

Electrical Supply for Version UOP4 MKII-G Before connecting the electrical supply ensure that the RCD/RCCB (23) and all miniature circuit breakers (24 a,b,c) are in the off (down position). Also ensure that all rotary controls are set to minimum and all switches are set to off on the front of the console. The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 220/240V, 60Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW

-

EARTH

BROWN

-

LIVE (HOT)

BLUE

-

NEUTRAL

Fuse Rating

-

13 AMP

The UOP4 MKII Solid/Liquid Extraction Unit is ready for commissioning. Refer to the Operational procedures section for details on how to operate the equipment and how to prepare samples of solid material ready for extraction.

27

Armfield Instruction Manual

Cold Water Supply Set the pressure regulator to minimum before connecting it to the cold water supply (pull the knob upwards then turn the knob fully anticlockwise). Connect a cold water supply to the inlet on the pressure regulator using ½” ID / 12.7 mm hose (not supplied by Armfield). The hose must be secured to the pressure regulator using a suitable hose clip (not supplied).

Drain Connection Connect the drain in the base of the extracted solids tank to a suitable floor drain using ½” ID / 12.7 mm hose (not supplied by Armfield). Note that the tank drains under gravity and the hose must not be restricted when the equipment is in use.

Using the Optional Educational Software and Data Logging Accessory An I/O Data Port connector (27) on the underside of the console allows the voltage signals from each of the measurements to be connected to the parallel port of a suitable PC using an Armfield IFD3 interface device. The interface device obtains its power from a mains output socket (25) marked OUTPUT at the rear of the console. This interface device together with the appropriate Windows based software is available as an optional accessory to accompany the UOP4 MkII. The operation of the interface is described in the instruction leaflet supplied with the IFD3. The operation of the Windows based software is described in the help text included as part of the software.

Commissioning All numerical references relate to the equipment diagrams. The following procedure is intended for initially checking that the equipment is operating correctly after assembly. This procedure should be started with the mains electrical supply disconnected. 1. Using the spirit level attached to the base of the extraction cell (7) alongside the rotor, adjust the feet at the bottom of the frame (1) to level the equipment in both axes. 2. Check that the mains switch on the front of the console (15) is in the OFF position. 3. Check that all of the rotary controls on the console (16, 17, 19a, 19b, & 19c) are set to ZERO (fully anti-clockwise). 4. Check that all three of the heater switches on the front of the console are switched OFF (20a, 20b & 20c). Note that the heaters should only be switched on when there is a consistent flow of liquid through the heaters. If the heaters are switched on with no liquid flowing they will rapidly overheat and cause the over temperature protection operate. This will reset automatically when the heaters cool to a satisfactory temperature but will take time. 5. Connect the mains electrical supply and check that it is switched on. Check the operation of the RCD (23) by pressing the TEST button. The RCD must trip when the button is pressed. If the RCD does not trip or it trips before 28

Installation pressing the test button then it must be checked by a competent electrician before the equipment is used. 6. Ensure that the RCD (23) and three miniature circuit breakers (24a, 24b & 24c) on the rear panel of the console are switched on. 7. Set the mains on/off switch (15) on the front of the console to the ON position. 8. With the heaters still switched off check that the displays on the three PID controllers (22a, 22b & 22c) are illuminated and displaying the temperatures at their respective sensing points (T1, T2 & T3) - initially at ambient temperature until the equipment is operational. The Temperature/Conductivity display (18) should also be illuminated. Set the selector switch adjacent to the display to position T4 and confirm that the reading is also of ambient temperature. Note: At this stage the conductivity probes should contain no liquid and so will not give a meaningful reading if the selector switch is set to positions C1, C2, C3 or C4. 9. To test the operation of the spiral feeder (10), set the feeder speed on/off switch (16) to the ON position then gradually turn the feeder speed control clockwise. The spiral should rotate progressively faster as the control is turned further clockwise. Once the feeder has been tested the control can be turned back to zero and the switch set to the off position. 10. To test the operation of the rotor on the extraction cell (7), set the rotor speed on/off switch (17) to the ON position then gradually turn the rotor speed control clockwise. The rotor should turn progressively faster as the control is turned further clockwise. Once the rotor has been tested the control can be turned back to zero and the switch se to the off position. Note: As the maximum rotational speed of the rotor is only 4 revolutions per hour it will take some time for the rotation to be apparent. 11. To test the operation of the three peristaltic pumps: Fill the Fresh Solvent Tank (11) with clean water. Set the rotary speed control (19a) for the first stage pump (3a) to 80%. Water should be ejected from the first stage sprinkler bar (6a) when the pipework has primed. When water has drained into the first stage solvent collection trough (8a) and a level has been established, set the rotary speed control (19b) for the second stage pump (3b) to 80%. When water has drained into the second stage solvent collection trough (8b) and a level has been established, set the rotary speed control (19c) for the third stage pump (3c) to 80%. Water should exit to the final miscella tank (13) when the pipework has primed. Note: For correct operation a water level of approximately 15 mm must be maintained inside the solvent collection troughs for the first and second stages (8a and 8b). The actual depth is not important but the relative speed of the pumps must be adjusted to ensure that these troughs do not run dry. Similarly

29

Armfield Instruction Manual these troughs must not overfill above the level of the elbow on the vent tube that is mounted through the sidewall of the trough. 12. To test the operation of the PID controllers and heaters: Ensure that water is flowing through the three stages of the system as described above. It may be necessary to adjust the relative speed of the pumps slightly to maintain a steady level in each of the solvent collection troughs. (If any tank runs dry then the next stage will be starved.) To avoid excessive overshoot when heating, initially adjust the setpoint of each controller to match the temperature on the display. If necessary, refer to the procedure for checking or adjusting the set point which is included in the description of the PID controllers. Switch on heater 1 (20a) then adjust the set point of the first stage controller (22a) to 40oC and allow the temperature reading to stabilise at 40oC. Switch on heater 2 (20b) then adjust the set point of the second stage controller (22b) to 45oC and allow the temperature to stabilise at 45oC. Switch on heater 3 (20c) then adjust the set point of the third stage controller to 50oC and allow the temperature to stabilise at 50oC. 13. To test the operation of the spray nozzle: Ensure that a water supply is connected to the pressure regulator and that the outlet in the base of the extracted solids tank is connected to a suitable drain. Adjust the height of the spray nozzle so that the tip of the nozzle is above the baffles inside the rotor but below the top edge of the rotor. Adjust the pressure regulator to give a spray pattern that washes the walls of the cells without excessive splashing or overspray (adjust the height of the spray nozzle if necessary). Check that water drains into the extracted solids tank and flows to drain via the outlet. Turn of the spray nozzle by turning the knob on the pressure regulator fully anticlockwise. Commissioning of the UOP4 MkII is complete. Switch off each of the heaters and set each of the pump speed controls to zero then switch off the main switch.

Electrical Wiring Diagram Click on the relevant link to invoke the Wiring Diagram: Wiring Diagram CDM27585 sheet 1 Wiring Diagram CDM27585 sheet 2 Printed Versions of this Instruction Manual Please note, all wiring diagrams are appended at the rear of this manual

30

Operation Where necessary, refer to the drawings in the Equipment Diagrams section.

Operating the Software Note: The diagrams in this section are included as typical examples and may not relate specifically to the individual product described in this instruction manual. The Armfield Software is a powerful Educational and Data Logging tool with a wide range of features. Some of the major features are highlighted below, to assist users, but full details on the software and how to use it are provided in the presentations and Help text incorporated in the Software. Help on Using the Software or Using the Equipment is available by clicking the appropriate topic in the Help drop-down menu from the upper toolbar when operating the software as shown:

Before operating the software ensure that the equipment has been connected to the IFD5 Interface (where IFD5 is separate from the equipment) and the IFD5 has been connected to a suitable PC using a USB lead. For further information on these actions refer to the Operation manual. Load the software. If multiple experiments are available then a menu will be displayed listing the options. Wait for the presentation screen to open fully as shown:

Before proceeding to operate the software ensure that IFD: OK is displayed at the bottom of the screen. If IFD:ERROR is displayed check the USB connection between the IFD5 and the PC and confirm that the red and green LED’s are both illuminated. If the problem persists then check that the driver is installed correctly (refer to the Operation manual).

31

Armfield Instruction Manual

Presentation Screen - Basics and Navigation As stated above, the software starts with the Presentation Screen displayed. The user is met by a simple presentation which gives them an overview of the capabilities of the equipment and software and explains in simple terms how to navigate around the software and summarizes the major facilities complete with direct links to detailed context sensitive ‘help’ texts. To view the presentations click Next or click the required topic in the left hand pane as appropriate. Click More while displaying any of the topics to display a Help index related to that topic. To return to the Presentation screen at any time click the View Presentation icon from the main tool bar or click Presentation from the dropdown menu as shown:

For more detailed information about the presentations refer to the Help available via the upper toolbar when operating the software.

Toolbar A toolbar is displayed at the top of the screen at all times, so users can jump immediately to the facility they require, as shown:

The upper menu expands as a dropdown menu when the cursor is placed over a name. The lower row of icons (standard for all Armfield Software) allows a particular function to be selected. To aid recognition, pop-up text names appear when the cursor is placed over the icon.

Mimic Diagram The Mimic Diagram is the most commonly used screen and gives a pictorial representation of the equipment, with continuously updated display boxes for all the various sensor readings, calculated variables etc. directly in engineering units. To view the Mimic Diagram click the View Diagram icon or click Diagram from the View drop-down menu as shown:

32

from the main tool bar

Operation

A Mimic diagram is displayed, similar to the diagram as shown:

The details in the diagram will vary depending on the equipment chosen if multiple experiments are available. In addition to measured variables such as Temperature, Pressure and Flowrate (from a direct reading flowmeter), calculated data such as Motor Torque, Motor Speed and Discharge / Volume flowrate (from pressure drop across an orifice plate) are continuously displayed in data boxes with a white background. These are automatically updated and cannot be changed by the user. Manual data input boxes with a coloured background allow constants such as Orifice Cd and Atmospheric Pressure to be changed by over-typing the default value, if required. The data boxes associated with some pressure sensors include a Zero button alongside. This button is used to compensate for any drift in the zero value, which is an inherent characteristic of pressure sensors. Pressing the Zero button just before starting a set of readings resets the zero measurement and allows accurate pressure measurements to be taken referenced to atmospheric pressure. This action must be 33

Armfield Instruction Manual carried out before the motor is switched on otherwise the pressure readings will be offset. The mimic diagram associated with some products includes the facility to select different experiments or different accessories, usually on the left hand side of the screen, as shown:

Clicking on the appropriate accessory or exercise will change the associated mimic diagram, table, graphs etc to suit the exercise being performed.

Control Facilities in the Mimic Diagram A Power On button allows the motor to be switched off or on as required. The button always defaults to off at startup. Clicking this button switches the power on (1) and off (0) alternately. A box marked Motor Setting allows the speed of the motor to be varied from 0 to 100% either stepwise, by typing in values, or using the up / down arrows as appropriate. It is usual to operate the equipment with the motor initially set to 100%, then reduce the setting as required to investigate the effect of reduced speed on performance of the equipment. When the software and hardware are functioning correctly together, the green LED marked Watchdog Enabled will alternate On and Off. If the Watchdog stops alternating then this indicates a loss of communication between the hardware and software that must be investigated. Details on the operation of any automatic PID Control loops in the software are included later in this section.

Data Logging Facilities in the Mimic Diagram There are two types of sampling available in the software, namely Automatic or Manual. In Automatic logging, samples are taken regularly at a preset but variable interval. In Manual logging, a single set of samples is taken only when requested by

34

Operation the operator (useful when conditions have to be changed and the equipment allowed to stabilize at a new condition before taking a set of readings). The type of logging will default to manual or automatic logging as appropriate to the type of product being operated. Manual logging is selected when obtaining performance data from a machine where conditions need to stabilize after changing appropriate settings. To record a set of set of data values from each of the measurement sensors click the main toolbar. One set of data will be recorded each time the

icon from the icon is clicked.

Automatic logging is selected when transients need to be recorded so that they can be plotted against time. Click the the

icon from the toolbar to start recording, click

icon from the toolbar to stop recording.

The type of logging can be configured by clicking Configure in the Sample dropdown menu from the upper toolbar as shown:

In addition to the choice of Manual or Automatic sampling, the parameters for Automatic sampling can also be set. Namely, the time interval between samples can be set to the required number of minutes or seconds. Continuous sampling can be selected, with no time limit or sampling for a fixed duration can be set to the required number of hours, minutes or seconds as shown:

Tabular Display To view the Table screen click the View Table icon click Table from the View dropdown menu as shown:

from the main tool bar or

35

Armfield Instruction Manual

The data is displayed in a tabular format, similar to the screen as shown:

As the data is sampled, it is stored in spreadsheet format, updated each time the data is sampled. The table also contains columns for the calculated values. New sheets can be added to the spreadsheet for different data runs by clicking the icon from the main toolbar. Sheets can be renamed by double clicking on the sheet name at the bottom left corner of the screen (initially Run 1, Run 2 etc) then entering the required name. For more detailed information about Data Logging and changing the settings within the software refer to the Help available via the upper toolbar when operating the software.

Graphical Display When several samples have been recorded, they can be viewed in graphical format.

36

Operation

from the main To view the data in Graphical format click the View graph icon tool bar or click Graph from the View drop-down menu as shown:

The results are displayed in a graphical format as shown:

(The actual graph displayed will depend on the product selected and the exercise that is being conducted, the data that has been logged and the parameter(s) that has been selected). Powerful and flexible graph plotting tools are available in the software, allowing the user full choice over what is displayed, including dual y axes, points or lines, displaying data from different runs, etc. Formatting and scaling is done automatically by default, but can be changed manually if required. To change the data displayed on the Graph click Graph Data from the Format dropdown menu as shown:

37

Armfield Instruction Manual

The available parameters (Series of data) are displayed in the left hand pane as shown:

Two axes are available for plotting, allowing series with different scaling to be presented on the same x axis. To select a series for plotting, click the appropriate series in the left pane so that it is highlighted then click the appropriate right-facing arrow to move the series into one of the windows in the right hand pane. Multiple series with the same scaling can be plotted simultaneously by moving them all into the same window in the right pane. To remove a series from the graph, click the appropriate series in the right pane so that it is highlighted then click the appropriate left-facing arrow to move the series into the left pane. The X-Axis Content is chosen by default to suit the exercise. The content can be changed if appropriate by opening the drop down menu at the top of the window. The format of the graphs, scaling of the axes etc. can be changed if required by clicking Graph in the Format drop-down menu as shown:

38

Operation

For more detailed information about changing these settings refer to the Help available via the upper toolbar when operating the software.

PID Control Where appropriate, the software associated with some products will include a single or multiple PID control loops whereby a function on the product can be manually or automatically controlled using the PC by measuring an appropriate variable and varying a function such as a heater power or pump speed. The PID loop can be accessed by clicking the box labelled PID or Control depending on the particular software:

A PID screen is then displayed as shown:

39

Armfield Instruction Manual

The Mode of operation always defaults to Manual control and 0% output when the software is loaded to ensure safe operation of the equipment. If appropriate, the operator can retain manual operation and simply vary the value from 0 to 100% in the Manual Output box, then clicking Apply. Alternatively, the PID loop can be changed to Automatic operation by clicking the Automatic button. If any of the PID settings need to be changed from the default values then these should be adjusted individually before clicking the Apply button. The controller can be restored to manual operation at any time by clicking the Manual button. The value in the Manual Output box can be changed as required before clicking the Apply button. Settings associated with Automatic Operation such as the Setpoint, Proportional Band, Integral Time, Derivative Time and Cycle Time (if appropriate) can be changed by the operator as required before clicking the Apply button. Clicking Calculations displays the calculations associated with the PID loop to aid understanding and optimization of the loop when changing settings as shown:

40

Operation

Clicking Settings returns the screen to the PID settings. Clicking OK closes the PID screen but leaves the loop running in the background. In some instances the Process Variable, Control variable and Control Action can be varied to suit different exercises, however, in most instances these boxes are locked to suit a particular exercise. Where the variables can be changed the options available can be selected via a drop-down menu.

Advanced Features The software incorporates advanced features such as the facility to recalibrate the sensor inputs from within the software without resorting to electrical adjustments of the hardware. For more detailed information about these advanced functions within the software refer to the Help available via the upper toolbar when operating the software.

Operating the Equipment Safe Operation The UOP4 MkII is designed for safe operation and can be operated safely by a person who fully understands the operation of the equipment. Before starting to operate the equipment all operators should note the following important points: 1. Operators should avoid liquids getting on to the electrical parts of the system since this could present an electric shock hazard and may trip the RCD. 2. Operators should not put their hands into the hopper (10) of the materials feeder while it is switched on since the spiral is very highly geared and could damage a persons fingers. 3. Operators should not put their hands into the rotor (7) when it is switched on. Although the speed of rotation is extremely slow and incorporates a slipping clutch, the rotor is very highly geared and could damage a persons fingers. 41

Armfield Instruction Manual 4. Although not toxic, the salt (Potassium Bicarbonate) and carrier (porous polymer pellets) need to be handled with care. Operators should avoid breathing in dust containing the Potassium Bicarbonate and should wear gloves to avoid contact with the salt in powder form or in solution. If clothing is contaminated with Potassium Bicarbonate it should be removed and any areas of skin which have been in contact should be thoroughly washed with clean water. 5. The heater (4a, 4b & 4c) in each stage of the process relies on flowing liquid to carry the heat to the temperature sensor downstream which is used by the PID controller to control the temperature. Each heater switch (20a, 20b & 20c) must therefore be switched off until water is flowing continuously through the appropriate heater. Over-temperature protection is fitted to each of the heaters for safety but it is good practice and will save time if the heaters are only switched after the system is primed and running. Over temperature indicators (21a, 21b & 21c) flash when the temperature is excessive and power to the appropriate heater has been cut. The protection will reset automatically when the temperature of the heater returns to normal.

Preparation of Materials Before starting to operate the equipment it will be necessary to prepare the solid material (carrier) to be extracted from. The recommended solid material for processing in the UOP4 MkII is ‘Microporous Polyamide 6-pellets’. This is an inert, plastic material in pellet form that offers a convenient porous carrier for the extractable material. A quantity of porous polymer pellets is supplied with the equipment for use as the solid carrier. The plastic pellets can be reclaimed and reused. Note: Solid carrier material other than the porous polymer pellets supplied with the equipment may contain dust, large particles or hard particles that could damage the equipment. For this reason it is important to check the suitability of alternative carriers before using them in the feeder or extraction cell. The recommended material for extraction is a salt called Potassium Bicarbonate (also called Potassium Hydrogencarbonate having the chemical symbol KHCO 3 ). Other materials may be used if required but the conductivity change with concentration will need to be defined by the user. The laboratory teaching exercises and exercises using UOP4MkII-303IFD software assume that Potassium Bicarbonate is used. The solid carrier can be prepared for use in the UOP4 MkII as follows (3 litre batches of material will be convenient to handle): 1. Ensure that the porous polymer pellets are thoroughly dry before attempting to absorb the salt into them. 2. If the pellets are not dry spread them onto drying trays and allow to air-dry, this process can be accelerated using an oven set to no more than 60ºC. 3. Measure a 3 litre batch of dry pellets. 4. Dissolve 500g of the extractable material (Potassium Bicarbonate) into 1.5 litres of water at room temperature.

42

Operation 5. Add the solution of Potassium Bicarbonate to 3 litres of dried porous polymer pellets and stir the mixture until the pellets are thoroughly wetted out with the solution. 6. Leave the pellets for approximately 24 hours to absorb the solution, stirring the mixture periodically to distribute the solution evenly. 7. Spread the wetted out pellets on to drying trays. If there is a small amount of unabsorbed solution it can be stirred into the pellets after it has been dried in the next stage. 8. Finally dry out the pellets, this process can be accelerated using an oven set to no more than 60oC. 9. Weigh the dried pellets and determine the proportion of Potassium Bicarbonate by weight (ConcS). Because of the low density of the pellets the ratio will be approximately 1:1.8 ie. 500 grams of KHCO 3 in a total weight of 900 grams of treated porous polymer pellets and ConcS = 55%. 10. Note: it is possible for the pellets to become electrostatically charged which may result in pellets sticking to the hopper surface. Care should be taken in storing the polymer to prevent electrostatic charging.

Calibration of Feed Pumps The user will find it useful to calibrate the peristaltic feed pumps (3a, 3b & 3c) so that the actual flow rate can be related to the setting of the rotary speed control (19a, 19b & 19c). Although the three pumps are identical in specification it is advisable to carry out a separate calibration for each as there may be slight differences due to tolerances. To calibrate each pump the following steps should be followed: 1. Check that the heaters are switched off using the three switches (20a, 20b & 20c) on the front of the console. Disconnect the flexible tubes attached to the pump making a note of the original connections 2. Connect a length of flexible tubing from a large beaker of water to the pump inlet and a similar flexible tube leading from the pump outlet to a measuring cylinder (typically 250 ml or 500 ml capacity). 3. Set the appropriate pump rotary speed control (19a, 19b or 19c) to setting 2.0. 4. Collect the water discharging from the pump for a timed period using the measuring cylinder and stopwatch then calculate the volume flowrate as follows:

5. Repeat the above step for settings of 4.0, 6.0, 8.0 and 10.0. 6. Draw a graph of flow rate (litres/hour) versus speed setting. The result should be a straight line (the pumps will not operate at low settings of the speed control). 7. Re-attach the flexible tubes from the pumps to their original positions. 43

Armfield Instruction Manual 8. Repeat the above steps for the two remaining pumps to produce similar graphs for those pumps. Copies of the three graphs produced using the above procedure should be kept with the equipment for reference.

Calibration of Feeder The user will find it useful to calibrate the feeder arrangement so that the actual delivery of solid material can be related to the setting of the rotary speed control. To calibrate the feeder the following steps should be followed: 1. Fill the hopper (10) with a dried sample of the solid carrier (porous polymer pellets containing Potassium Bicarbonate) to be processed. 2. Rotate the rotor of the extraction cell until one cell aligns with the aperture in the base. Ensure that the rotor and base are dry to prevent solid material from adhering. Place a suitable receptacle beneath the shute on the underside of the aperture to collect any solid discharging from it. 3. Switch on the feeder and set the feeder rotary speed control (16) to setting 2.0. 4. When the spiral has filled and solid is discharging at a steady rate, collect the solid for a timed period using a stopwatch. Weigh the solid collected then calculate the mass flowrate as follows:

5. Repeat the above steps for settings of 4.0, 6.0, 8.0 and 10.0. 6. Draw a graph of mass flow rate (kg/hour) versus speed setting. The result should be a straight line (the feeder will not operate at low settings of the speed control). A copy of the graph produced using the above procedure should be kept with the equipment for reference.

Calibration of Rotor Speed The user will find it useful to calibrate the rotor so that the actual speed of rotation can be related to the setting of the rotary speed control. For accurate results the rotor should be calibrated under normal operating conditions containing wet material. To calibrate the rotor the following steps should be followed: 1. Place a mark on the base of the extraction cell (7) adjacent to the wall of the rotor. 2. Fill the hopper (10) with a dried sample of the solid carrier (porous polymer pellets containing Potasium Bicarbonate) to be processed. 3. Switch on the rotor and set the rotor speed control (17) to setting 2.0.

44

Operation 4. Switch on the feeder and set the feeder rotary speed control (16) to setting 2.0. 5. Switch on the pumps (19a, 19b & 19c) and allow the system to stabilise. 6. Using a stopwatch record the time taken for one compartment to move past the marks on the base. For accuracy repeat the measurement several times. 7. Calculate the rotor speed as follows:

8. Repeat the above steps for settings of 4.0, 6.0, 8.0 and 10.0. 9. Draw a graph of rotor speed (revs/hour) versus speed setting. The result should be a straight line (the rotor will not operate at low settings of the speed control). A copy of the graph produced using the above procedure should be kept with the equipment for reference.

Method for Setting the Temperature Controllers Having selected a suitable temperature for the solvent in the three stages of the process it will be necessary for the user to set this temperature on the three PID controllers (22a, 22b & 22c). The operating range is between ambient and 55oC (it will not be possible to control the temperature with a setting at or below the ambient air temperature). The set point of the controllers can be checked and changed as follows: Make sure that the heaters are switched off using the three heater switches (20a, 20b & 20c) on the front panel of the console and then switch on the UOP4 MkII (15). The digits on the three PID controllers should illuminate and, after an initial check, display the temperature at the three sensing points. To check the current set point: Press either the increase key

or decrease key

briefly.

The display will automatically return to the process temperature. To change the current set point: Press either the increase key will be displayed. Press and hold the increase value of the digit is displayed.

or decrease key

or decrease

briefly. The current set point

key as required until the required

The display will automatically return to the process temperature. Note that the heaters should not be switched on until the flows of liquid in the heaters are steady. 45

Armfield Instruction Manual Note: For optimum control of the temperatures within the process, without excessive overshoot, the setpoint of each controller should be set to ambient temperature when the equipment is first switched on with water flowing. Adjustment to the required setpoint during operation will then give smooth control without excessive overshoot. Similarly it is suggested that the temperature of stage 1 should be allowed to stabilise before increasing the setpoint of stage 2 and the temperature of stage 2 should be allowed to stabilise before increasing the setpoint of stage 3.

Method for Starting Up and Balancing the Three Liquid Stages Before using the extractor system as a multi-stage process users may find it useful to operate the three solvent stages independently from the rest of the system, this will allow the user to master the techniques that will be needed to keep the three stages running in balance. It is important to balance the stages since they cascade from one to another. If one stage pump is running too fast relative to the other pumps there will be a tendency for the trough which is supplying the pump to run dry and for the next trough down the line to over flow. Out of balance running can lead to instability and intermittent liquid flows can cause the heater protection circuits to operate. Note: For correcty operation the first and second stage troughs must not be allowed to run dry and the level must not be allowed to rise so that the elbow on the vent pipe (mounted through the side wall of each trough) becomes submerged. The objective of the following method is to fill the stage troughs to a depth of approximately 15 mm of water and to set the stage pumps running so that the three stages run in balance at the desired operating speed: 1. Check that the mains switch (15) on the front of the console is in the off position. 2. Check that all of the rotary controls (16, 17, 19a, 19b & 19c) on the console are set to zero (fully anti-clockwise). 3. Check that all three of the heaters are switched OFF using the switches (20a, 20b & 20c) on the front of the console. 4. Switch the on the mains power using the mains switch (15) on the front of the console. 5. Switch the RCD/RCCB (23) and circuit breakers (24a, 24b, 24c & 24d) on the back of the console to the on position. 6. Fill the fresh solvent tank (11) with clean water. 7. To save time, fill solvent collection trough one (8a) and solvent collection trough two (8b) to a depth of approximately 20 mm by pouring water in through the rotor. 8. Pour water into the third stage trough (8c) until the water level reaches the point where it drains into the final miscella tank (13). Note that the final trough will drain completely.

46

Operation 9. Prime each of the pumps (3a, 3b & 3c) in turn by setting the appropriate speed control (19a, 19b or 19c) to maximum until water exits the appropriate sprinkler bar (6a, 6b or 6c). 10. Once the system has been primed the three pumps can be adjusted to run at the desired rate (eg. setting 5.0 on the potentiometer for half of maximum flow). Water from the fresh solvent tank should now be cascading through the three stages via the three pumps and troughs and then draining into the final miscella tank. 11. After the system has been running for a while the levels in solvent collection troughs one and two will indicate how well the flowrates in the system are balanced. If the system is perfectly in balance then the levels in troughs one and two will not have changed, however if the levels are changing an alteration to the system will be needed. To make the necessary changes the following steps can be followed: 12. Use the flow rate of pump 1 as the master setting for all of the solvent flows by leaving the speed control (19a) fixed at the desired rate. The user will find that this technique will greatly reduce any complexity involved in balancing the system since it can now be balanced using alterations to the two other pumps only. 13. Having set pump 1, work from right to left through the solvent stages when making changes ie. first look at the trend/level in trough 1 (8a) and alter the speed setting (19b) of pump 2 to change the trend. If the level in trough 1 is falling reduce the speed of pump 2. Conversely, if the level in trough 1 is rising increase the speed of pump 2. If the level has changed substantially from the half full position temporarily set the speed to maximum or minimum as appropriate then reset the speed to normal when the level has been returned to half full. Note the change in pump speed necessary to restore the balance. 14. Once pump 2 has been set to maintain the level in trough 1 the user can look at trough 2 (8b). The control of the level in trough 2 is slightly different to that in trough 1 since trough 2 has a variable flow of liquid into it (controlled by pump 2) as well as a variable flow of liquid being removed from it (controlled by pump 3). When the user adjusts the speed of pump 3 to maintain the level in trough 2 it will be necessary to consider the effect of any changes that have been made to the speed of pump 2 as well as any existing change in the level. If for example trough 2 was maintaining its level before an increase in pump 2 speed, it will be necessary to increase the speed of pump 3 by a similar amount in order to compensate for the increased flow into the trough from pump 2 . 15. The level in the final trough (8c) does not require any adjustment since this is self-controlling. The balancing procedure described above should be repeated as frequently as is required. Users will find that as the balance becomes more precise, the period between speed adjustments will become longer and the required adjustments will become finer. Maintaining the balance will be easier if trends in the liquid levels are spotted early and small adjustments are made to the flows to compensate.

47

Armfield Instruction Manual Once the user has balanced the system it is possible to retain the approximate pump settings for future use by making a note of the potentiometer settings (19a, 19b & 19c).

Method for Start Up and Operation Once the points relating to safety (listed earlier) have been understood the operator should read through all of the steps for operating the system listed below before starting to use the system. The first step in starting up the system is to balance the solvent stages at the required flow rate as described in the previous section. Once the solvent system is running in balance the procedure is as follows: 1. Switch on the extractor rotor and adjust the speed control (17) to give the required rotational speed (typically two revolutions per hour). Note that at two revs per hour it will take three minutes for one of the dividers in the rotary cell to pass a fixed point. 2. Half fill the hopper (10) of the spiral feeder with untreated solid carrier (dry porous polymer pellets). 3. Switch on the feeder and adjust the speed control (16) so that the compartments of the rotary cell are filled to between one-third and half height as they pass under the feeder. Note that the top surface of the solid will adopt a saw tooth profile due to the action of the baffles. 4. As the filled compartments pass beneath the sprinkler bars (6c, 6b then 6a because of the counter current operation) the balance in the collection troughs will change because of hold-up in the material. Because of this the speed of the second and third stage pumps will need to be adjusted regularly during the first rotation to prevent any of the collection troughs from running dry. Once all of the compartments in the system have been filled the balance of the solvent system should progressively approach an equilibrium state and adjustments to the pump speeds should be minimal. When the solid material reaches the aperture in the base at the rear of the extractor it will be necessary to turn on the spray nozzle so that the material is washed into the extracted solids tank. Adjust the position of the nozzle and pressure regulator as required to prevent overspray. 5. More experienced operators may wish to reduce the time taken to start up the system filling all of the compartments of the rotary cell with untreated solid carrier then wetting it with water by hand before balancing the pump settings. 6. Once the system has settled down and the solvent stages are running in balance the PID heater controllers (22a, 22b & 22c) can be set to the desired operating temperature (using the method described earlier) and switched on (20a, 20b & 20c). For smooth control the setpoint of each stage should be increased to the required value after the previous stage has stabilised. 7. The next stage in the start up procedure is to replace the carrier with pellets containing Potassium Bicarbonate, this is done by simply filling the feeder hopper with the treated solid carrier as the untreated material runs out. 8. Once the system has been started up as described above the parameters such as the operating temperatures, solvent flow rate, solid feed rate and 48

Operation rotor speed can be varied as required. Although the extraction process is continuous and should settle to an equilibrium condition, the way in which this condition is established is just as important as the final condition. Readings should therefore be taken at regular intervals throughout the operation to allow the transient responses to be studied. When running the UOP4 MkII it is important that the user should carefully monitor the process since the apparatus will need to be kept topped up with fresh solvent and extractable material. The user will also have to empty the waste solids hopper and check that the solvent stages remain in balance.

Shut Down Procedure Shutting down the UOP4 MkII is a simple process which can be accomplished as follows: 1. Switch off all three of the heaters using the switches on the control console (21a, 21b & 21c). 2. Switch off the spiral material feeder (16). 3. Set the speed of the rotor to maximum (17) in order to empty the rotor of the remaining solid materials. 4. Fill the fresh solvent tank (11) with clean water then set the speed of the pumps to maximum (19a, 19b & 19c) to thoroughly flush the heaters, temperature sensors, conductivity probes, sprinkler bars and flexible tubing. 5. When all of the solid material from the rotor has discharged into the extracted solids tank (12) the rotor can be switched off (17) and the spray nozzle can be turned off by setting the pressure regulator to minimum (knob full anticlockwise). 6. When the heaters, sensors, flexible tubing etc have been thoroughly flushed through with fresh water the pumps can be set to minimum (19a, 19b &19c). 7. Switch off the power to the unit using the switch (15) on the control console and then switch off and unplug the mains supply.

Cleaning after use After use all of the solid material and liquid solutions should be emptied from the equipment before flushing the process pipework with clean water. Fill the Fresh Solvent Tank with clean water then operate the three stages of the process with the pumps at maximum speed to flush the system. Operation with the water at elevated temperature will be beneficial (set point on each PID controller at maximum). If the equipment will be operated within a few days of commissioning then the pipework should remain filled with de-ionised water to prevent deterioration of the electrodes inside the conductivity probes. After cleaning, fill the Solvent tank with deionised water then pump this through the system to leave the probes filled. If the equipment will not be operated for a longer period then the conductivity probes should be removed from the pipework, flushed with de-ionised water then air-dried to prevent deterioration of the electrodes inside the probes.

49

Armfield Instruction Manual After prolonged use it may be necessary to flush the system with a weak acid to remove any build up of the salt in the pipework etc. Refer to the Routine Maintenance section for further details if this is necessary. Periodically it will be necessary to clean the Feeder and Extractor Cell. Details of the procedure for dismantling these components is given below. The general procedure for cleaning the equipment is to disassemble the parts which need cleaning, removing any electrical assemblies and then to wiping the non electrical parts with a cloth soaked in warm soapy water (abrasive cleaners and volatile solvents should not be used). Note that when cleaning the equipment operators should avoid contact with the chemicals used and if necessary should wear protective gloves. 1. Cleaning of the extractor assembly: a. To prevent damage to the sprinkler bars remove the quick release fitting from the end of each sprinkler bar (push the grey collar against the body of the fitting while pulling the fitting). b. Unclamp the spray nozzle at the rear of the extractor, raise and rotate the rigid tube so that the tip of the nozzle is clear of the rotor. c. Disconnect the electrical cable to the feeder from the socket on the underside of the console. d. Remove the feeder by unscrewing the thumbscrews that secure it to the frame. Carefully tip any remaining solid carrier into a suitable container. e. Disconnect the electrical cable to the top of the central hub on the extraction cell from the socket on the underside of the electrical console. f.

Remove the top of the extractor (including the hub and rotor as a complete assembly) from the base by unscrewing the two fixing screws (large thumb nuts) on top of the hub. The hub / rotor will simply lift away from the base revealing the mesh that allows the solvent to drain into the troughs underneath.

g. Carefully wipe the rotor with a damp cloth soaked in warm soapy water to remove any contamination. h. With the hub / rotor removed the mesh which supports the solid carrier can be cleaned using warm soapy water Ensure that the central recess for the hub of the rotor is clear of any solid particles.

50

i.

The collection troughs can usually be cleaned adequately by pouring warm soapy water through the mesh from above. However, if contamination is severe, the mesh can be removed to gain acces to the troughs for more thorough cleaning. The mesh should be lifted from the recess in the base, starting at one end and taking care not to distort it. After cleaning, the troughs and mesh should be dried using a soft cloth then reassembled by pressing the mesh into the recess, again taking care not to distort the mesh. When correctly assembled the mesh should be flush with the surrounding PVC base.

j.

While the feeder / extractor hub are removed the frame can be cleaned to remove any dust or spillage using a damp cloth.

Operation k. After cleaning, the extractor should be dried with a soft cloth and reassembled as follows: Locate the central hub in the central recess of the base and rotate the hub until the dowel pin locates in the hole. Pass the two fixing screws through the two holes in the top of the hub and tighten the screws to secure the hub to the base. Reconnect the electrical cable to the base of the console. Refit the feeder to the frame using the thumbscrews. l.

Reposition the spray nozzle with the tip of the nozzle inside the cells but clear of the baffles.

m. Reconnect the flexible tubing to the spray bars on the extraction cell. Refer to Figure 1 and 3 in the equipment diagrams for details of the connections of the flexible tubing/sprinkler bars to the extractor. 2. Cleaning of Spiral Conveyor Assembly a. Cleaning of the feeder will not usually be necessary when using the porous polymer pellets supplied by Armfield. However, after prolonged use or in unusual circumstances cleaning of the spiral conveyor and hopper will be necessary. Remove any remaining material from the hopper by running the conveyor or by tipping the material into a suitable container after removing the assembly from the frame by unscrewing the thumbscrews. b. Detach the drive motor from the rest of the assembly by undoing the four caphead screws which secure the motor to the hopper. Pull the motor away from the hopper to separate the link between the motor and the spiral. Remove the drive coupling from the end of the spiral (where the motor was fitted) by unscrewing the grub screw that retains the coupling. c. Having removed the motor and drive coupling undo the three thumb nuts on the other end of the tube containing the spiral and disassemble the remainder of the conveyor. d. After cleaning with warm water, the components of the conveyor can be dried with a soft cloth and then reassembled. Assembly of the components is simply the reverse of the disassembly.

51

Equipment Specifications Overall Dimensions Approximate overall dimensions of the equipment in millimetres are: Height

-

1520 mm

Width

-

770 mm

Depth

-

560 mm

I/O Port Pin Connections To allow access to the measurement signals in applications other than when using an Armfield IFD3, the connections to the 50 way connector (27) are listed below for information: Pin No

Channel No

Signal Function

Analog Outputs (0-5 V dc exported from socket): 1

Ch 0 Signal

2

Ch 0 Return

3

Ch 1 Signal

4

Ch 1 Return

5

Ch 2 Signal

6

Ch 2 Return

7

Ch 3 Signal

8

Ch 3 Return

9

Ch 4 Signal

10

Ch 4 Return

11

Ch 5 Signal

12

Ch 5 Return

13-21

Not Used

Temperatures T1 to T4 (0-60 oC) and Conductivities C1 to C4 (0-100 mS) via analog switch

Speed setting of feeder (0-100%)

Speed setting of rotor (0-100%)

Speed setting of pump 1 (0-100%)

Speed setting of pump 2 (0-100%)

Speed setting of pump 3 (0-100%)

Analog Inputs (0-5V dc input from socket):

52

Equipment Specifications

Not Used

22-25

Digital Outputs (0-5V dc): Not Used Digital Inputs (0-5V dc): 38

Ch 0

Analog switch

39

Ch 1

Analog switch

40

Ch 2

Analog switch

41

Ch 3

Analog switch

42

Digital Ground

43

Ch 4

44-46

Not Used

47

Digital Ground

48-50

Not Used

Inhibit analog switch

Environmental Conditions This equipment has been designed for operation in the following environmental conditions. Operation outside of these conditions may result reduced performance, damage to the equipment or hazard to the operator. a. Indoor use; b. Altitude up to 2000 m; c. Temperature 5 °C to 40 °C; d. Maximum relative humidity 80 % for temperatures up to 31 °C, decreasing linearly to 50 % relative humidity at 40 °C; e. Mains supply voltage fluctuations up to ±10 % of the nominal voltage; f.

Transient over-voltages typically present on the MAINS supply; NOTE: The normal level of transient over-voltages is impulse withstand (overvoltage) category II of IEC 60364-4-443;

g. Pollution degree 2. Normally only nonconductive pollution occurs. 53

Armfield Instruction Manual Temporary conductivity caused by condensation is to be expected. Typical of an office or laboratory environment

54

Routine Maintenance Responsibility To preserve the life and efficient operation of the equipment it is important that the equipment is properly maintained. Regular maintenance of the equipment is the responsibility of the end user and must be performed by qualified personnel who understand the operation of the equipment.

General In addition to regular maintenance the following notes should be observed: 1. The equipment should be disconnected from the electrical supply when not in use. 2. Check the operation of the RCD by pressing the TEST button. The RCD must trip when the button is pressed. If the RCD does not trip or it trips before pressing the test button then it must be checked by a competent electrician before the equipment is used. 3. When the equipment is not in use the conductivity probes (C1, C2 and C3) should ideally be left full of de-ionised water, this will help to maintain the accuracy of the conductivity probes when returned to normal operation. 4. To preserve the life and the efficient running of the equipment it is important to keep the equipment clean. Refer to the section Cleaning After Use for further information. 5. After prolonged use it may be necessary to adjust the screws that limit the vertical movement of the rotor. Adjustment will be necessary if there is excessive vertical movement of the rotor allowing the solid carrier to escape between the wall of the rotor and the base plate. The adjusting screws are accesible by removing the top cover on the central hub after releasing the two screws that secure the hub to the base. Note that if these screws are overtightened the excessive friction will cause the protection clutch to slip resulting in no drive to the rotor. 6. At regular intervals inspect the electrodes inside the conductivity probes (C1, C2 and C3) for contamination. Contamination of the glass wall or metal electrodes inside the probes indicates that salt is also contaminating the pipework and needs to be removed for satisfactory operation of the equipment. If there is a need to remove contamination then the system should be flushed through with a solution of 0.1M hydrochloric acid at room temperature, this will remove any contamination from the probes and pipework. After flushing with acid the system should be thoroughly flushed through with clean water to remove all traces of the acid. If the probes are removed for cleaning then users should avoid using sharp objects or abrasives to clean the probes since the coating of the electrode plates and connecting wires in the probes may be damaged. The plated surface of the electrodes and their connecting wires should be a uniform colour and free from any blemishes or scratches since this can cause erratic measurement results. If any damage to the coating is found it will be necessary to replace the electrode.

55

Armfield Instruction Manual 7. At regular intervals inspect the filters (9a, 9b and 9c) for blockage of the wire mesh. The filter can be opened for cleaning by unscrewing the two halves of the body (lugs on each half of the body assist in opening the filter). 8. At regular intervals inspect the filter in the transparent bowl of the pressure regulator for blockage. The filter can be removed for cleaning by unscrewing the bowl from the body of the pressure regulator.

Configuration of the PID Temperature Controllers If, for any reason, the configuration of the controller has been altered or corrupted it will be necessary to restore the settings as follows: a. Make sure that the heater switches on the front of the console are switched off then switch on the console. After the initialisation checks each of the controllers should display the process temperature. b. To access the User Menu press the scroll key for 3 seconds then release the key. The code for the first parameter will be displayed, alternating with the set value. To change the value press the increase or decrease key as required to achieve the requied value. When the value is set correctly press the scroll key to check the other settings within the User Menu. c. To access the Setup Menu press the scroll key and decrease key simultaneously then release both keys. The code for the first parameter will be displayed, alternating with the set value. To change the value press the increase or decrease key as required to achieve the required value. When the value is set correctly press the scroll key to check the other settings within the Setup Menu. d. Once the desired figure has been entered the scroll key will access the next parameter for checking. The display will automatically revert to the sensed temperature if no key is pressed for a period of approximately 2 minutes. To return to normal operation immediately press the increase keys simultaneously then release both keys.

and decrease

The suggested values for the controller parameters are as follows: CODE

PARAMETER

UNITS

SETTING

USER MENU A1.SP

Alarm set point

o

60

ShiF

Shift process value

o

0.0

Pb 1

Proportional band output 1

o

72.0

ti 1

Integral time

Sec

28

td 1

Derivative time

Sec

5

A1.Hy

Hysteresis alarm 1

o

1

56

C C C

C

Routine Maintenance

PL 1

Power limit Output 1

100

SETUP MENU FunC

Function complexity level

FuLL

Conn

Communication interface type

nonE

in 1

Input 1 Sensor type selection

0-1V

in1.u

Input 1 unit selection

Pu

dP 1

Input 1 decimal point selection

no.dP

in1.L

Input 1 low scale value

0

in1.H

Input 1 high scale value

60

in 2

Input 2 Signal type selection

nonE

out 1

Output 1 Function

reVr

o1.ty

Output 1 Signal type

SSrd

CYC 1

Output 1 cycle time

o1.Ft

Output 1 Failure transfer mode

BPLS

out 2

Output 2 Function

nonE

A1.Fn

Alarm 1 Function

PV1.H

A1.nd

Alarm 1 Operation

norn

A1.Ft

Alarm 1 Failure transfer mode

on

A2.Fn

Alarm 2 Function

nonE

EiFn

Event input function

nonE

PVnd

PV mode selection

PV 1

FiLt

Filter damping time constant

SELF

Self tuning function

nonE

SLEP

Sleep mode function selection

nonE

SP.nd

Set point mode selection

SP1.2

SP1.L

SP1 Low scale value

0

Sec

Sec

1

0.5

57

Armfield Instruction Manual

SP1.H

SP1 High scale value

60

diSF

Display format

PV

SEL1

Select 1st parameter

nonE

SEL2

Select 2nd parameter

nonE

SEL3

Select 3rd parameter

nonE

SEL4

Select 4th parameter

nonE

SEL5

Select 5th parameter

nonE

Maintenance of the UOP4 MkII does not require access to the electrical circuits or components inside the console. However in the event of an electrical problem or recalibration of the conditioning circuits, it may be necessary for a competent electrician to gain access to the console as follows: Ensure that the console is disconnected from the electrical supply (not just switched off) before removing the cover from the console. Unscrew the fixings, which retain the blue metal cover then carefully remove the cover itself. It will be necessary to disconnect the earth lead attached to the cover. An electrical wiring diagram showing the mains and DC electrical circuits inside the console is included to assist in fault finding.

Recalibration of the Thermocouple Conditioning Circuits This procedure requires access to the circuits inside the console and must be carried out by a competent electrician. The thermocouple conditioning circuits (which provide readings from the thermocouples fitted to each of the stages) are located on a PCB inside the console. These circuits are calibrated before despatch and should not require recalibration. However, should recalibration become necessary the following procedure should be used: a. Ensure the equipment has been connected to the electrical supply and switched on for at least 20 minutes before re-calibrating the temperature conditioning circuits. Re-calibration can be effected using a thermocouple calibrator or using the thermocouples themselves immersed in ice and hot water (the PID controllers are limited to a maximum of 60oC). b. Remove the blue cover from the console as described above then identify the circuit board with the temperature adjustment potentiometers on it (see Figures 6 & 7 in the equipment diagrams). c. If using a thermocouple calibrator, disconnect the appropriate thermocouple from the socket adjacent to the pump then connect the calibrator to the vacant socket. If using ice and hot water, remove the thermocouple from the quick release fitting by pushing back the grey collar while pulling the thermocouple (do not remove the thermocouple by pulling the lead). 58

Routine Maintenance d. To set the zero point on one of the temperature circuits the user should connect the calibrator and set the output to 0oC or place the thermocouple into a beaker of water and crushed ice as appropriate. Once the temperature reading on the appropriate PID controller has stabilised the user should identify the appropriate zero potentiometer (see Figure 7 in the equipment diagrams) and adjust it to give a reading of 0oC. e. To set the span of the thermocouple set the output from the calibrator to 60oC or place the thermocouple into a beaker of hot water at approximately 60oC, along with a thermometer. Once the temperature has stabilised the span potentiometer should be adjusted to give the temperature of the liquid on the relevant PID controller display. f.

Repeat the adjustment of the zero and span potentiometers until no further adjustment is necessary.

g. Having calibrated one of the thermocouples, the process can be repeated for any of the other thermocouples as necessary. When the calibration is complete the thermocouples can be refitted to the equipment and the console cover must be replaced.

Recalibration of the Conductivity Conditioning Circuits This procedure requires access to the circuits inside the console and must be carried out by a competent electrician. The conductivity conditioning circuits (which provide readings from the four conductivity probes fitted to each of the three solvent stages and the miscella collection stage) are located on a single printed circuit board located inside the console. These circuits are calibrated before dispatch and should not require recalibration. However, should re-calibration become necessary the following procedure should be used: a. Ensure the equipment has been connected to the electrical supply and switched on for at least 20 minutes before re-calibrating the conductivity conditioning circuits. Re-calibration can be effected using a reference solution with a typical conductivity of 80 mS. It will be necessary to adjust the temperature of the reference solution or adjust the actual conductivity reading to compensate for any temperature difference from its calibration temperature using the table supplied with the solution. b. Remove the blue cover from the console as described above then identify the circuit board with the conductivity adjustment potentiometers on it (see Figure 8 in the equipment diagrams). c. Disconnect the four conductivity probes by unplugging connector 8 from the conductivity circuit board. (Refer to Figure 8 in the equipment diagrams which shows the position of conn 8.) d. Connect an AC Volt meter (range AC mV) to one of the pairs of conductivity probe pins on the circuit board (refer to Figure 8 in the equipment diagrams which shows the position of the pins). Adjust potentiometer VR2 on the PCB to give a reading of 50 mV (RMS) on the voltmeter (probe excitation voltage for the four probes), then disconnect the voltmeter.

59

Armfield Instruction Manual e. Reconnect the plug for the four probes and then carefully remove the probes to be calibrated by disconnecting the flexible tubing and removing the glass body from its support. f.

Fill a small beaker with the conductivity reference solution. Immerse the probe to be calibrated and a suitable thermometer in the reference solution. It is important to make sure that the conductivity probe is completely full of the liquid and to allow the probe to soak in the solution for a few minutes to allow the temperature to stabilise.

g. From the table supplied with the conductivity reference solution determine the actual conductivity of the solution at the measured temperature. Set the selector switch (on the front of the console) to display the conductivity of the probe being calibrated. Adjust the appropriate potentiometer to give a reading on the display to match the conductivity of the reference solution (to identify the correct potentiometer refer to Figure 8 in the equipment diagrams). Having calibrated one of the probes, the process can be repeated for any of the other probes as necessary. When the calibration is complete the probes can be refitted to the equipment and the console cover must be replaced.

RCD Test Test the RCD by pressing the TEST button at least once a month. If the RCD button does not trip when the Test button is pressed then the equipment must not be used and should be checked by a competent electrician.

60

Laboratory Teaching Exercises Index to Exercises Exercise A: Batch Extraction - Open Loop Exercise B: Batch Extraction - Closed Loop Exercise C: Single Stage Continuous Extract Exercise D: Two Stage Continuous Extraction Exercise E: Three Stage Continuous Extraction Project Work When using the appropriate Armfield Teaching Software (optional accessory) the Teaching Exercises may differ slightly and it is suggested that reference is made to the help text incorporated in the software rather than this manual.

Introduction and Background Solid liquid extraction appears to be a relatively simple process in which a solvent percolates through a bed of solid particles, dissolving, and therefore extracting some of the soluble component from the solid particles (the solid carrier). The overall extraction process involves a series of steps, some of which are more complex individual operations as follows: a. Solvent is applied to the particles of solid that are to be extracted from. b. The solvent permeates through the bed of solid particles. c. The soluble component on the surface of the solid particles is washed off easily by the solvent. d. The soluble component contained within the solid particles is gradually dissolved by the solvent. The solute created diffuses through the pores in the solid to the outside of the particle. e. The solute at the surface of the particle diffuses into the static layer of solvent in contact with the particle. f.

The concentrated solute adjacent to the solid particles mixes with the main bulk of the solution.

g. The final miscella (solvent containing the soluble component) is drained from the bed of solid particles and collected for further processing. h. The spent solid material is removed from the process. In extraction processes the degree of extraction of the soluble component is heavily dependent on the concentration of the solvent and the amount of the soluble component present. When the solvent is fresh and there is a large amount of soluble component available there will be a high degree of extraction. Conversely when the solvent has a high solute content and the soluble component in the solid is low (solid exhausted) a point can be reached where there is no net extraction taking place and an equilibrium is reached. 61

Armfield Instruction Manual There are two obvious ways in which an equilibrium state can happen: a. The solvent can become saturated with the solute so that there is no longer any net transfer of the soluble component to the solvent, regardless of the amount of the soluble component available to be extracted. It is possible to increase the extraction in this case by increasing the temperature, which allows the solvent to absorb more solute. Alternatively the solute concentration in the solvent can be reduced by adding fresh solvent. Note that increasing the concentration of the soluble component in the solid by adding fresh solids will have no effect if the solvent is saturated. b. When the soluble component content of the solid material is low, a point may be reached where the concentration of the solute at the surface of the particles may have the same concentration as the main body of solvent. The result is no net transfer of solute to the main body of the solvent. In this case a temperature change will have little effect. To extract more solute it will be necessary to generate a difference in concentrations. Adding fresh solvent will reduce the concentration in the main body of solvent and so generate a difference in concentration that will allow the solute to move from the solid particles to the main body of solvent by osmosis. Alternatively increasing the content of soluble component by adding fresh solids to the process will increase the solute concentration in the contact solvent and so generate the difference in concentration that is needed for transfer of the solute to the main body of the solvent. The principles outlined above refer to solid liquid extraction in general and can be applied to both the continuous and batch configurations of the UOP4 MkII.

Nomenclature Name

Symbol

Unit

Speed setting of first stage pump

N1

% of max

Speed setting of second stage pump N2

% of max

Speed setting of third stage pump

N3

% of max

Speed setting of feeder

NF

% of max

Speed setting of rotor

NR

% of max

Volume flowrate of final miscella

F4

m3/hr

Mass flowrate of solvent in first stage M1 (From N1)

kg/hr

Mass flowrate of solvent in second stage (From N2)

kg/hr

62

M2

Laboratory Teaching Exercises

Mass flowrate of solvent in third stage (From N3)

M3

kg/hr

Mass flowrate of solvent lost in the process

ML

kg/hr

Mass flowrate of solids into process (From N4)

MS

kg/hr

Output of KHCO 3 from process

MO

kg/hr

Temperature of fresh solvent entering stage 1

T1

°C

Temperature of first miscella entering T2 stage 2

°C

Temperature of second miscella entering stage 3

T3

°C

Temperature of final miscella exiting T4 process

°C

Temperature of solvent in fresh solvent tank

TS

°C

Conductivity of solvent entering stage 1

C1

mS

Conductivity of solvent entering stage 2

C2

mS

Conductivity of solvent entering stage 3

C3

mS

Conductivity of final miscella exiting process

C4

mS

Initial conductivity of the solvent (closed loop batch extraction only, from C1)

Cinit

MS

Concentration of KHCO 3 in solid

ConcS

%wt

Concentration of KHCO 3 in first miscella

Conc2 %wt (From C2)

Concentration of KHCO 3 in second miscella

Conc3 %wt (From C3)

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Armfield Instruction Manual

Concentration of KHCO 3 in final miscella

Conc4 %wt (From C4)

Percentage of KHCO 3 extracted from  solids

%

Specific heat of solvent

Cp

kJ/kgoC

Density of solvent



kg/m3

Power input to first stage solvent heater

Q1

W

Power input to second stage solvent Q2 heater

W

Power input to third stage solvent heater

Q3

W

Total power input to process

Qt

W

Graphs of Concentration

64

Exercise A: Batch Extraction - Open Loop Objective To demonstrate the operation of the batch extractor system when configured for open loop extraction and to show how the concentration of solute in the solvent changes with processing time.

Method In open loop extraction fresh solvent is fed into the batch extractor vessel continuously and the miscella leaving the process is monitored continuously. By measuring the conductivity and temperature of the solvent stream at regular intervals as it exits the extractor it is possible to monitor the extraction of the Potassium Bicarbonate (KHCO 3 ) from the batch of material.

Equipment Required UOP4 MkII Solid Liquid Extraction Unit Solid carrier - porous polymer pellets containing Potassium Bicarbonate (prepared in advance) Stopwatch (not supplied)

Optional Equipment None

Theory/Background Open loop extraction on a batch of material is not a usual configuration but it interesting to observe the effect when fresh solvent is fed continuously through the batch of material and this concept can be applied to each individual stage in the continuous process which will be studied in a later exercise. It is possible to make the following observations about this configuration. a. In most batch extraction systems both the concentration of the solvent and the available soluble component reduce as the soluble component is extracted by the solvent. Open loop batch extraction differs in that while the available soluble component reduces, the concentration of solvent does not, because of this there will always be a difference of solute concentration between the contact solvent and the main body of the solvent (so long as there is any soluble component left). The difference between the concentrations means that in theory 100% extraction can be achieved. b. In an open loop system the rate of extraction will be dependent on the solvent temperature, the solvent flow rate and the amount of soluble material left in the particles. The extraction rate will not be affected by changes in solvent concentration as the process progresses because the solvent entering the batch vessel is always fresh solvent. If the solvent flow rate and temperature are constant the rate of extraction will be related to the amount of extractable material remaining, thus the rate of extraction should progressively slow down. Because extraction commences as soon as the solvent contacts the solid particles it will be necessary to preheat the solvent to the required operating temperature before allowing it to flow through the batch extraction vessel. This simple precaution will 65

Armfield Instruction Manual allow the transient changes in conductivity to be monitored throughout the process without additional transients during start-up due to changing solvent temperature.

Equipment Set Up a. Configure the system for open loop batch extraction as depicted in the flow diagram below. Water from the fresh solvent tank is pumped upwards through the first stage heater then passes upwards through the batch extractor before overflowing to the final miscella tank.

Procedure Start Up a. Check that the UOP4 MkII is switched off, all switches are set to off and all rotary controls are set to minimum on the front panel of the console. b. Fill the fresh solvent tank with clean water. c. Place the cloth over the batch vessel then insert the filling tube so that the cloth lines the vessel. Pour the prepared solid carrier (porous polymer pellets containing Potassium Bicarbonate) into the filling tube then gradually withdraw the filling tube to leave the vessel full of the prepared solid carrier. Ensure that the top of the sample does not protrude above the side tapping at the top of the vessel. d. Open the bypass valve (lever in line with valve body) at the base of the extractor vessel to divert the solvent to the final miscella tank. e. Plug in and switch on the UOP4 MkII. Adjust the setpoint of controller 1 to match the temperature indicated on the display (to avoid excessive overshoot when heating is required).

66

Exercise A f.

Set pump speed one to give the required flow rate (typically 5.0 on the speed control, approximately 6 litres per hour).

g. Switch on heater ONE ONLY then adjust the set point on the stage 1 temperature controller to 40oC. Note that the heater must only be on when there is a steady flow of liquid through the heater. Monitor temperature T1 (indicated on the stage 1 temperature controller) and wait until it has stabilised. Once the temperature of the water has stabilised the extraction can commence as follows.

Extraction Before commencing the extraction it will be necessary to organise recording of the required data. The following readings will be required: T1 Temperature of solvent entering the batch vessel T4 Temperature of solvent leaving the batch vessel C1 Conductivity of solvent entering the batch vessel (will remain constant) C4 Conductivity of solvent leaving the batch vessel In manual operation it will be necessary to switch the multi function display on the console between C1, C4 and T4 in order to take down these readings on a regular basis (typically once per minute) as the process progresses. T1 is indicated continuously on the stage 1 temperature controller. Start the stopwatch as you close the bypass valve at the bottom of the extractor vessel to feed the solvent upwards through the vessel. When the miscella (solvent containing the extract) reaches the overflow at the top of the vessel it will flow into the miscella tank (it may be necessary to disconnect the flexible tube briefly to allow the tube to prime). Once the sensors have filled with liquid the data can be recorded at regular intervals until the conductivity reading C4 falls towards to zero. When the process has finished switch off the heater before the solvent pump. If time permits the exercise can be repeated at different solvent flowrates or solvent temperatures to investigate their effect on the rate of extraction. It will be necessary to replace the exhausted solid carrier in the extractor with prepared solid carrier.

Presentation of Results and Analysis The first stage in analysing the results is to turn the pairs of conductivity and temperature readings (C4 – C1 with T4) into values of percentage weight KHCO 3 , this is done by linear interpolating between points on the conversion graph which is presented in Graphs of Concentration. Having converted the values produce a graph showing the percentage weight of extracted material in the miscella against time. Note: When using the UOP4 MkII with the optional PC based interface and software (UOP4MkII-303IFD) the conversion of the data and the plotting of the graph is carried out automatically in real time. Comment on the profile of the graph in relation to the theory of open loop extraction eg.

67

Armfield Instruction Manual a. Does the miscella concentration tend to zero with increasing time or does it reach an equilibrium point? b. Does the rate of extraction decrease as more of the soluble component is extracted? When considering the above it may be necessary to take into account factors such as fluctuating temperature of the solvent or washing of soluble material from the surface of the solid particles as the processing starts. If results were obtained at different solvent flowrates or different solvent temperatures compare the graphs of concentration against time and comment on the effect of flowrate and/or temperature.

68

Exercise B: Batch Extraction - Closed Loop Objective To demonstrate the operation of the batch extractor system when configured for closed loop extraction and to compare the results with predicted values.

Method In closed loop extraction the solvent draining from the batch extractor is returned to the inlet of the extractor so that the same solvent is continuously recycled. By measuring the conductivity and temperature of the solvent stream at regular time intervals it is possible to monitor the extraction of the Potassium Bicarbonate (KHCO 3 ) from the batch of material.

Equipment Required UOP4 MkII Solid Liquid Extraction Unit Solid carrier - porous polymer pellets containing Potassium Bicarbonate (prepared in advance). Stopwatch (not supplied) Measuring cylinder (not supplied)

Optional Equipment None

Theory/Background In closed loop batch extraction the fixed batch of extractable material is processed by a fixed amount of solvent, which is continuously circulated through the extractor. It is possible to make the following observations about this configuration. a. In this system the solute concentration in the main body of the solvent rises as the process proceeds and the solute content of the solvent in contact with the particles declines progressively with time until they reach a similar concentration and an equilibrium is found (assuming that the solvent does not become saturated before equilibrium is reached). b. When equilibrium is reached, the concentration of solute in the solvent will depend on the volume of solvent used in the process and the amount of soluble component initially in the solid. c. The temperature of the solvent will have an effect on the speed of the extraction but it will not have any effect on the final concentration. d. The flow rate of the solvent will have an effect on the speed of the extraction but it will not have any effect on the final concentration.

Equipment Set Up Configure the system for closed loop batch extraction as depicted in the flow diagram below. Water from the final miscella tank is pumped upwards through the first stage heater then passes upwards through the batch extractor before overflowing back into the final miscella tank for recirculation

69

Armfield Instruction Manual Note: When operating with a small volume of solvent it may be easier to place a small beaker, containing the solvent, inside the final miscella tank to increase the depth of the solvent and submerge the end of the flexible tubing to the pump suction.

When setting up the closed loop batch configuration it will be necessary to choose the volume of solvent to use in the loop. If a small volume of solvent is used the concentration of KHCO 3 in the miscella will tend to be higher but the percentage extraction will be lower. If the volume of the solvent is very low the solvent may become saturated before equilibrium between the contact solvent and the main body of the solvent is reached. Method for choosing the volume of solvent Choose an equilibrium concentration that is less than the saturation point at ambient temperature (typically 7% wt). E.g. With 700 ml of porous pellets in the batch extractor containing 117 gm of Potassium Bicarbonate a solution of 7% by wt is achieved with a batch of 1.67 litres of water. Measure the mass of the solids that are to be processed in the batch extractor and calculate the mass of KHCO 3 in the solids using the known proportions of the soluble and non-soluble components (see Preparation of Materials). Calculate the mass of water that would produce the required percentage weight given the mass of KHCO 3 in the solids (this assumes that equilibrium is reached with a uniform concentration in the contact solvent and the main body of the solvent). Check that the calculated mass and therefore volume of water will fill the pump, heater, flexible tubing, sensors, overcome the static hold up of the solids and be enough for there to be a workable liquid level in the miscella tank. If there is not enough water the planned percentage weight will need to be reduced.

70

Exercise B

Procedure Start Up Check that the UOP4 MkII is switched off, all switches are set to off and all rotary controls are set to minimum on the front panel of the console. Ensure that the flexible tubing connected to the pump suction is fully submerged in the solvent and will not float to the top of the liquid causing intermittent liquid flows. Place the prepared solid carrier in a measuring cylinder and note the level. Place the cloth over the batch vessel then insert the filling tube so that the cloth lines the vessel. Pour the prepared solid carrier into the filling tube then gradually withdraw the filling tube to leave the vessel full of the prepared solid carrier. Ensure that the top of the sample does not protrude above the side tapping at the top of the vessel. Note the level of solid carrier remaining in the measuring cylinder to determine the amount of solid carrier in the extractor. Fill the final miscella tank, or beaker if appropriate, with the required volume of clean water. Open the bypass valve (lever in line with valve body) at the bottom of the extractor vessel to divert the solvent back to the final miscella tank. Plug in and switch on the UOP4 MkII. Adjust the setpoint of controller 3 to match the temperature indicated on the display (to avoid excessive overshoot when heating is required). Set pump speed three to give maximum flow rate (typically 13.5 litres per hour) and check that the volume of solvent available will be enough for the solvent loop to operate when the batch extractor is introduced later on. Switch on heater THREE ONLY then adjust the set point on the stage 3 temperature controller to 40oC. Note that the heater must only be on when there is a steady flow of liquid through the heater. Monitor temperature T3 (indicated on the stage 3 temperature controller) and wait until it has stabilised. Measure and record the initial conductivity of the solvent Cinit indicated as C3. Once the temperature of the water has stabilised the extraction can commence as follows.

Extraction Before commencing the extraction it will be necessary to organise recording of the required data. The following readings will be required: T3 Temperature of solvent entering the batch vessel T4 Temperature of solvent leaving the batch vessel C3 Conductivity of solvent entering the batch vessel C4 Conductivity of solvent leaving the batch vessel In manual operation it will be necessary to switch the multi function display on the console between C3, C4 and T4 in order to take down these readings on a regular basis (typically once per minute) as the process progresses. T3 is indicated continuously on the stage 3 temperature controller.

71

Armfield Instruction Manual Start the stopwatch as you close the bypass valve at the bottom of the extractor vessel to feed the solvent upwards through the vessel. When the miscella (solvent containing the extract) reaches the overflow at the top of the vessel it will flow into the miscella tank Once the sensors have filled with liquid the data can be recorded at regular intervals until the conductivity readings C3 and C4 are the same – no further extraction is occurring. When the process has finished switch off the heater before the solvent pump. If time permits the exercise can be repeated with a different initial volume of solvent to investigate the effect on the final concentration. Different solvent flowrates or solvent temperatures could also be tried to investigate their effect on the rate of extraction. It will be necessary to replace the exhausted solid carrier in the extractor with prepared solid carrier.

Results and Analysis The first stage in analysing the results is to turn the pairs of conductivity and temperature readings (C3 – Cinit with T3 and C4 – Cinit with T4) into values of percentage weight KHCO 3 . This is done by linear interpolating between points on the conversion graph which is presented in Graphs of Concentration. Having converted the results produce a graph showing the percentage weight of extracted material in the final miscella against time. Also produce a graph of difference in percentage weight between solvent entering the batch vessel (Conc3 from C3) and solvent leaving the batch vessel (Conc4 from C4) against time. Note: When using the UOP4 MkII with the optional PC based interface and software the conversion of the data and the plotting of the graphs is carried out automatically in real time. Comment on the profile of the graphs in relation to the theory of closed loop extraction eg. a. Does the miscella concentration tend reach an equilibrium point as the process proceeds? b. How does the equilibrium concentration of the KHCO 3 compare with the predicted value? When considering the above it may be necessary to take into account factors such as fluctuating temperature of the solvent or washing of soluble material from the surface of the solid particles as the processing starts. If results were obtained with a different initial volume of solvent or differing solvent flowrate/temperature compare the graphs of concentration against time and comment on the effect of volume, flowrate and/or temperature.

72

Exercise C: Single Stage Continuous Extract Objective To demonstrate the operation of the extractor when configured for single stage continuous solid liquid extraction and to assess the efficiency of the process.

Method By measuring the conductivity and temperature of the final miscella as it leaves the process it is possible to find the percentage weight of extracted Potassium Bicarbonate (KHCO 3 ) in the final miscella and therefore the degree of extraction taking place. Similar measurements of the fresh solvent entering the process allow the efficiency of the process to be investigated.

Equipment Required UOP4 MkII Solid Liquid Extraction Unit Solid carrier - porous polymer pellets containing Potassium Bicarbonate (prepared in advance). Stopwatch (not supplied) Measuring cylinder, typically 250 ml (not supplied)

Optional Equipment None

Theory/Background When the system is configured for single stage continuous extraction the fresh solid material is fed into the system using the spiral material feeder. The solid material is moved through the system by the rotating cell and fresh solvent sprinkled onto it continuously drains through it. (Refer to the flow diagram in Equipment Set-up below.) Once the solid material has been processed it discharges into the extracted solids tank. The miscella containing the soluble component is collected in the final miscella tank. Single stage continuous extraction is an open loop system and the rate of extraction will be dependent on variables such as the solvent temperature, the solvent flow rate, the solids feed rate, the amount of solute in the dry solid and the characteristics of the contact between the solid particles and the liquid. Because the extraction is continuous the process will stabilise after an initial period; however, transient changes as the process starts up and stabilises will be of interest, as well as the readings when steady state is achieved. The % weight of KHCO 3 in the final miscella can be determined from measurements of temperature and conductivity of the final miscella using the conversion graphs in Graphs of Concentration. When choosing the operating parameters of an extraction process the main objectives are as follows: a. To make the final miscella as concentrated as possible – to minimise the cost of further processing when recovering the soluble component from the solvent. 73

Armfield Instruction Manual b. To use the minimum amount of solvent – to reduce operating costs. c. To lose the minimum amount of solvent – solvent retained in the solids after processing d. To maximise product output – to process the required amount of product in the minimum time. e. To extract the maximum percentage of the valuable soluble component from the feed – any soluble component remaining in the solids after processing is wasted. f.

To minimise the energy input to the process (operating at the lowest practicable temperature)– to reduce operating costs.

It is clear that all of these objectives are inter-related and that any attempt to compare how a system performs with different combinations of settings would require a comprehensive series of tests to determine the individual effects of each parameter. Such a test is suggested in the Project Work section. The efficiency of the process can be assessed by considering the following parameters: Concentration of the final miscella. Amount of soluble component extracted. Amount of soluble component remaining in the solids after processing. Amount of solvent remaining in the solids after processing. Energy required to perform the extraction.

Equipment Set Up Configure the equipment for single stage continuous extraction as depicted in the flow diagram below. Water from the fresh solvent tank is pumped upwards through the first stage heater and sprinkled onto the surface of the solid material which is moved beneath the sprinkler by the rotor. The miscella draining from the bottom of the rotor is collected in the final miscella tank.

74

Exercise C

Configuration for Single stage continuous extraction

Procedure Start Up Check that the UOP4 MkII is switched off, all switches are set to off and all rotary controls are set to minimum on the front panel of the console. Fill the fresh solvent tank with clean water. Fill the hopper of the spiral feeder with prepared solid carrier. Plug in and switch on the UOP4 MkII. Adjust the setpoint of controller 1 to match the temperature indicated on the display (to avoid excessive overshoot when heating is required). Set pump one to give the required flow rate (typically 5.0 on the speed control, approximately 6 litres per hour). When solvent appears at the sprinkler bar measure and record the temperature TS of the solvent direct from the fresh solvent tank indicated on the stage 1 temperature controller (T1) before the heater is switched on. Switch on heater ONE ONLY then adjust the set point on the stage 1 temperature controller to 40oC and allow the temperature to stabilise. Note that the heater must only be on when there is a steady flow of liquid through the heater. Monitor temperatures T1 and T4 (T1 indicated on the stage 1 temperature controller, T4 indicated on the panel meter via the selector switch) and wait until the temperatures have stabilised. Once the temperatures have stabilised the extraction can commence as follows.

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Armfield Instruction Manual

Extraction Before commencing the extraction it will be necessary to organise recording of the required data. The following readings will be required: T1 Temperature of solvent entering rotor T4 Temperature of final miscella C1 Conductivity of solvent entering the rotor (will remain constant) C4 Conductivity of final miscella In manual operation it will be necessary to switch the multi function display on the console between C1, C4 and T4 in order to take down these readings on a regular basis (typically once per minute) as the process progresses. Start the rotor cell and adjust the speed control to give the required rotational speed (typically 5.0 on the speed control, approximately 2 revs per hour). Turn on the spiral material feeder and adjust the speed control to give the required depth of material in the cells of the rotor (typically 30 -50% full). When the solid material reaches the aperture in the base at the rear of the extractor it will be necessary to turn on the spray nozzle so that the material is washed into the extracted solids tank. Adjust the position of the nozzle and pressure regulator as required to prevent overspray. Note: It will be necessary to refill the hopper with prepared solid carrier as the exercise proceeds. Start the stopwatch and commence recording the above readings when the first cell containing the solid material reaches the sprinkler bar. As the solvent extracts the KHCO 3 from the solid carrier the output from conductivity probe C4 will rise and eventually stabilise. Note: When the system has achieved steady state small cyclic variations will be observed in the reading from conductivity probe C4 as the individual cells of the rotor present fresh solid material to the solvent stream. This effect can be observed more clearly when logging results continuously using the optional PC logging interface and software (Armfield product code UOP4MkII-303IFD).

Readings at steady state Once the system has reached steady state the following measurements should be recorded: Feeder speed setting

NF

%

Rotor speed setting

NR

%

Pump 1 speed setting

N1

%

Temperature of solvent at stage 1

T1

o

76

C

Exercise C

Conductivity of solvent at stage 1

C1

mS

Temperature of final miscella

T4

o

Conductivity of final miscella

C4

mS

C

Using a measuring cylinder and stopwatch collect a timed sample of the final miscella to determine the flowrate of solvent leaving the process (F4 litres/hr). When shutting down the process switch off the heater before the solvent pump. If time permits the exercise can be repeated at different solvent flow rates, or solvent temperatures to investigate their effect on the rate of extraction and the efficiency of the process. Similarly, the effect of the solid feed rate and/or the rotor speed can be investigated.

Presentation of Results and Analysis From the measurements taken while the process was stabilising calculate the concentration of the KHCO 3 in the final miscella by converting the readings of (C4 – C1) and T4 into values of percentage weight KHCO 3 (using the conversion graphs in Graphs of Concentration). Plot the graph of percentage weight of extracted material in the final miscella against time. Comment on the shape of the graph as the process stabilises. Using the calibration graphs for the equipment where appropriate (refer to Operational Procedures for details) convert the above measurements taken at steady state as follows: Mass Flowrate of solid material (from NF using calibration graph)

MS

kg/hr

Mass Flowrate of solvent entering the process (from N1 using calibration graph)

M1

kg/hr

Mass Flowrate of final miscella (= F4 x density  of the solvent)

M4

kg/hr

Loss of solvent in the process (= M1 – M4)

ML

kg/hr

Concentration of KHCO 3 in the solid (from preparation data) ConcS

%wt

Input of KHCO 3 to the process (= MS x ConcS/100)

kg/hr

MI

Concentration of KHCO 3 in the miscella (from C4 – C1 and Conc4 T4 using graph)

%wt

Output of KHCO 3 from the process (= M1 x Conc4/100)

MO

kg/hr



%

Percentage of KHCO 3 extracted from the solids (= 100 x

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Armfield Instruction Manual

MO/MI) Energy input to the process (primarily heating of the solvent) (= 0.277 x M1 x (T1 – TS) x Cp)

Q1

Watts

Note factor of 0.2777 for M1 in kg/hr and Cp in kJ/kg/K

Comment on the efficiency of the process by considering the magnitude of the calculated values obtained when the process has achieved steady state (the appropriate parameters are suggested in the Theory section above). If results were taken under different operating conditions compare the results and comment on the effect of the changes on the efficiency of the process.

78

Exercise D: Two Stage Continuous Extraction Objective To demonstrate the operation of the solid liquid extractor when configured for two stage continuous extraction in counter current flow, to determine the contribution of each stage in the extraction process and to compare the results with those obtained from the single stage exercise.

Method By measuring the changes in conductivity and temperature of the streams of solvent at each stage of the process it is possible to find the percentage weight of extracted Potassium Bicarbonate (KHCO 3 ) in the solvent streams. From this data the user can determine the degree of extraction that is taking place at each stage.

Equipment Required UOP4 MkII Solid Liquid Extraction Unit Solid carrier - porous polymer pellets containing Potassium Bicarbonate (prepared in advance). Stopwatch (not supplied) Measuring cylinder, typically 250 ml (not supplied)

Optional Equipment None

Theory/Background When the system is configured as a two stage counter current flow extractor the fresh solid material and the fresh solvent are fed into the system from opposite ends of the process (refer to the flow diagram below). The solid material is moved through the system by the rotating cell and the solvent effectively flows through the material in the opposite direction being pumped to the sprinkler bars in the first and second stages. Once the solid material has been processed it discharges into the extracted solids tank. The miscella containing the soluble component is collected in the final miscella tank. In the counter current arrangement the most concentrated solids are processed by the least concentrated solvent and vice versa. This arrangement is used in industrial processing because it is generally more efficient than co-current operation. Similarly two-stage extraction is more efficient than single stage extraction. Two stage continuous extraction is an open loop system and the rate of extraction will be dependent on variables such as the solvent temperature, the solvent flow rate, the solids feed rate, the amount of solute in the dry solid and the characteristics of the contact between the solid particles and the liquid. Because the extraction is continuous the process will stabilise after an initial period however, transient changes as the process starts up and stabilises will be of interest as well as the readings when steady state is achieved.

79

Armfield Instruction Manual The % weight of KHCO 3 in the first miscella and final miscella can be determined from measurements of temperature and conductivity of the appropriate miscella using the conversion graphs in Graphs of Concentration. When choosing the operating parameters of an extraction process the main objectives are as follows: a. To make the final miscella as concentrated as possible – to minimise the cost of further processing when recovering the soluble component from the solvent. b. To use the minimum amount of solvent – to reduce operating costs. c. To lose the minimum amount of solvent – solvent retained in the solids after processing d. To maximise product output – to process the required amount of product in the minimum time. e. To extract the maximum percentage of the valuable soluble component from the feed – any soluble component remaining in the solids after processing is wasted. f.

To minimise the energy input to the process (operating at the lowest practicable temperature)– to reduce operating costs.

It is clear that all of these objectives are inter-related and that any attempt to compare how a system performs with different combinations of settings would require a comprehensive series of tests to determine the individual effects of each parameter. Such a test is suggested in the Project Work section. The efficiency of the process can be assessed by considering the following parameters: Concentration of the final miscella. Amount of soluble component extracted. Amount of soluble component remaining in the solids after processing. Amount of solvent remaining in the solids after processing. Energy required to perform the extraction.

Equipment Set Up Configure the system for two stage continuous extraction as depicted in the flow diagram below. Water from the fresh solvent tank is pumped upwards through the first stage heater and sprinkled onto the surface of the solid material which has already been processed and moved beneath the sprinkler by the rotor. The first miscella draining from the bottom of the rotor is pumped upwards through the second stage heater and sprinkled onto the surface of the dry unprocessed solid material. The final miscella draining from the bottom of the rotor is collected in the final miscella tank. The flow of solvent and solid material is countercurrent.

80

Exercise D

Configuration for two stage continuous countercurrent extraction

Procedure Start Up Check that the UOP4 MkII is switched off, all switches are set to off and all rotary controls are set to minimum on the front panel of the console. Fill the solvent tank with fresh water. Fill collection trough one (right-hand side) to approximately 20mm depth by pouring water through the mesh at the base of the rotor. Pour water into collection trough two (middle trough) until the water drains through the pipework into the final miscella tank. Set the speed of pump one to maximum to purge air from the first stage of the process. When water drips from the first sprinkler bar stop the pump. Set the speed of pump two to maximum to purge air from the second stage of the process. When water drips from the second sprinkler bar stop the pump. After priming it may be necessary to top up the level of water in the first trough to return it to 20mm depth. Note: the final trough will always run empty. Once the system has been primed the two pumps can be switched on and adjusted to run at the desired solvent flow rate (typically setting 4.0 on the speed controls). The solvent stage system should now be taking liquid from the fresh solvent tank, cascading it through the two stages via the two pumps and troughs and then draining it into the final miscella tank. After the system has been running for a while any imbalance in the stages will be indicated by a change in level in the first stage collection trough. If the level is falling reduce the speed of pump two. If the level is rising increase the speed of pump two. 81

Armfield Instruction Manual Do not adjust the speed of pump one during the exercise. It will be necessary to check the level at regular intervals and to make small adjustments when required. Adjust the setpoint of controllers 1 and 2 to match the temperature indicated on the display (to avoid excessive overshoot when heating is required). Start the rotor cell and adjust the speed control to give the required rotational speed (typically 5 on the speed control, approximately 2 revs per hour). Put some untreated solid carrier in the hopper of the spiral material feeder. Turn on the spiral material feeder and adjust the speed control to give the required depth of material in the cells of the rotor (typically 30 - 50% full). When the solid material reaches the aperture in the base at the rear of the extractor it will be necessary to turn on the spray nozzle so that the material is washed into the extracted solids tank. Adjust the position of the nozzle and pressure regulator as required to prevent overspray. Note: It may be necessary to refill the hopper with untreated solid carrier until the system has stabilised and extraction can commence. Allow the cells of the rotor to fill with untreated solid carrier. When the dry material passes beneath the sprinkler bars it may be necessary to make small adjustments to pump two to maintain the level in collection trough one. Measure and record the temperature TS of the solvent direct from the fresh solvent tank indicated on the stage 1 temperature controller (T1) before the heater is switched on. Once the system has settled down and the solvent stages are running in balance switch on heater ONE then adjust the set point on temperature controller ONE to 40oC. When T1 has stabilised switch on heater TWO then adjust the set point of temperature controller TWO to 40°C. Note that no heater should be switched on until there is a steady flow of liquid through the heater. Monitor temperatures T1 and T2 (indicated on the appropriate temperature controller) and wait until the temperatures have stabilised. When the temperatures have stabilised the extraction can commence as follows.

Extraction Before commencing the extraction it will be necessary to organise recording of the required data. The following readings will be required to show the transient response as the system stabilises: T1 Temperature of solvent entering the first cell of the rotor T2 Temperature of miscella entering the second cell of the rotor T4 Temperature of final miscella leaving the second cell C1 Conductivity of solvent entering the first cell of the rotor (will remain constant) C2 Conductivity of miscella entering the second cell of the rotor

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Exercise D C4 Conductivity of final miscella leaving the second cell In manual operation it will be necessary to switch the multi function display on the console between C1, C2, C4 and T4 in order to take down these readings on a regular basis (typically once per minute) as the process progresses. T1 and T2 are indicated continuously on the appropriate temperature controllers. Allow the hopper to empty of untreated solid carrier then fill the hopper with solid carrier containing the KHCO 3 just as the untreated solid carrier runs out. Start the stopwatch when the hopper is filled. Note: It will be necessary to refill the hopper with treated solid carrier as the exercise proceeds. As the solvent extracts the Potassium Bicarbonate from solid carrier the outputs from conductivity probes C2 and C4 will rise and eventually stabilise. Once the system has reached a steady state the appropriate temperatures and the conductivities can be recorded. Note: When the system has achieved steady state small cyclic variations will be observed in the readings from conductivity probes C2 and C4 as the individual cells of the rotor present fresh solid material to the solvent stream. This effect can be observed more clearly when logging results continuously using the optional PC logging interface and software (Armfield product code UOP4MkII-303IFD).

Readings at steady state Once the system has reached steady state the following measurements should be recorded: Feeder speed setting

NF

%

Rotor speed setting

NR

%

Pump 1 speed setting

N1

%

Pump 2 speed setting

N2

%

Temperature of solvent at stage 1

T1

o

Temperature of solvent at stage 2

T2

o

Temperature of final miscella

T4

o

Conductivity of solvent at stage 1

C1

mS

Conductivity of solvent at stage 2

C2

mS

Conductivity of final miscella

C4

mS

C C C

Using a measuring cylinder and stopwatch collect a timed sample of the final miscella to determine the flowrate of solvent leaving the process (F4 litres/hr).

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Armfield Instruction Manual When shutting down the process switch off the heater before the solvent pump. If time permits the exercise can be repeated at different solvent flow rates, or solvent temperatures to investigate their effect on the rate of extraction and the efficiency of the process. Similarly, the effect of the solid feed rate and/or the rotor speed can be investigated.

Presentation of Results and Analysis From the measurements taken while the process was stabilising calculate the concentration of the KHCO 3 in the first miscella and final miscella by converting the readings of C2 –C1 with T2 and C4 – C1 with T4 into values of percentage weight KHCO 3 (using the conversion graphs in Graphs of Concentration). Plot the graph of percentage weight of extracted material in the first miscella and final miscella against time. Comment on the shape of the graphs as the process stabilises. What is the contribution of each stage in the process? Using the calibration graphs for the equipment where appropriate (refer to Operational Procedures for details) convert the above measurements taken at steady state as follows: Mass Flowrate of solid material (from NF using calibration graph)

MS

kg/hr

Mass Flowrate of solvent entering the process (from N1 using calibration graph)

M1

kg/hr

Mass Flowrate of final miscella (= F4 x density  of M4 the solvent)

kg/hr

Loss of solvent in the process (= M1 – M4)

ML

kg/hr

Concentration of KHCO 3 in the solid (from preparation data)

ConcS

%wt

Input of KHCO 3 to the process (= MS x ConcS/100) MI

kg/hr

Concentration of KHCO 3 in the first miscella (from C2 – C1 and T2 using graph)

kg/hr

Conc2

Concentration of KHCO 3 in the final miscella (from Conc4 C4 – C1 and T4 using graph)

%wt

Output of KHCO 3 from the process = M1 x Conc4/100)

MO

kg/hr

Percentage of KHCO 3 extracted from the solids

 (= 100 x MO/MI)

%

Energy input to stage 1 of the process (primarily heating of the solvent) (= 0.277 x M1 x (T1 – TS) x Q1 Cp) Note factor of 0.2777 for M1 in kg/hr and Cp in

84

Watts

Exercise D

kJ/kg/K Energy input to stage 2 of the process (primarily heating of the solvent) (= 0.277 x M2 x (T2 – T4) x Cp) Note factor of 0.2777 for M2 in kg/hr and Cp in kJ/kg/K. Note as temperature of fluid entering the second stage heater cannot be directly measured and T4 is taken to be equivalent temperature.

Q2

Watts

Total energy input to process (= Q1 + Q2)

Qt

Watts

Comment on the efficiency of the process by considering the magnitude of the calculated values obtained when the process has achieved steady state (the appropriate parameters are suggested in the Theory section above). Compare the results obtained with those for single stage extraction (Exercise C) and comment on the effect of the second stage in the process. If results were taken under different operating conditions compare the results and comment on the effect of the changes on the efficiency of the process.

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Exercise E: Three Stage Continuous Extraction Note: It is suggested that operators have performed Exercise D (two stage continuous extraction) and understand the technique for balancing the individual stages before attempting to operate the more complex three stage process described in this exercise.

Objective To demonstrate the solid liquid extractor when configured for three stage continuous extraction in counter current flow, to determine the contribution of each stage in the extraction process and to compare the results with those obtained from the single and two stage exercises.

Method By measuring the changes in conductivity and temperature of the streams of solvent at each stage of the process it is possible to find the percentage weight of extracted Potassium Bicarbonate (KHCO 3 ) in the solvent stream at each stage. From this data the user can determine the contribution that each stage is making in the extraction and the degree of extraction that is taking place.

Equipment Required UOP4 MkII Solid Liquid Extraction Unit Solid carrier - porous polymer pellets containing Potassium Bicarbonate (prepared in advance). Stopwatch (not supplied) Measuring cylinder approximately 250 ml (not supplied)

Optional Equipment None

Theory/Background The three-stage process is similar to the two-stage process demonstrated in Exercise D with solvent and solid material passing continuously through the process in opposite directions. The additional stage improves the efficiency of the process but the balancing of the stages is made more difficult because the flow of solvent in the later stages are both affected by the flow of solvent in the first stage and the flow of solvent in the second stage is also affected by the flow of solvent in the third stage. In the counter current arrangement the most concentrated solids are processed by the least concentrated solvent and vice versa. This arrangement is used in industrial processing because it is generally more efficient than co-current operation. Similarly three-stage extraction is more efficient than two-stage extraction. Three stage continuous extraction is an open loop system and the rate of extraction will be dependent on variables such as the solvent temperature, the solvent flow rate, the solids feed rate, the amount of solute in the dry solid and the characteristics of the contact between the solid particles and the liquid. Because the extraction is continuous the process will stabilise after an initial period however, transient changes as the process starts up and stabilises will be of interest as well as the readings when steady state is achieved. 86

Exercise E The % weight of KHCO 3 in the first miscella, second miscella and final miscella can be determined from measurements of temperature and conductivity of the appropriate miscella using the conversion graphs in Graphs of Concentration. When choosing the operating parameters of an extraction process the main objectives are as follows: a. To make the final miscella as concentrated as possible – to minimise the cost of further processing when recovering the soluble component from the solvent. b. To use the minimum amount of solvent – to reduce operating costs. c. To lose the minimum amount of solvent – solvent retained in the solids after processing d. To maximise product output – to process the required amount of product in the minimum time. e. To extract the maximum percentage of the valuable soluble component from the feed – any soluble component remaining in the solids after processing is wasted. f.

To minimise the energy input to the process (operating at the lowest practicable temperature)– to reduce operating costs.

It is clear that all of these objectives are inter-related and that any attempt to compare how a system performs with different combinations of settings would require a comprehensive series of tests to determine the individual effects of each parameter. Such a test is suggested in the Project Work section of this instruction manual. The efficiency of the process can be assessed by considering the following parameters: Concentration of the final miscella. Amount of soluble component extracted. Amount of soluble component remaining in the solids after processing. Amount of solvent remaining in the solids after processing. Energy required to perform the extraction.

Equipment Set Up Configure the system for three stage continuous extraction as depicted in the flow diagram below. Water from the fresh solvent tank is pumped through the first stage heater and sprinkled onto the surface of the solid material which has already been processed twice. The solid material is moved beneath the sprinklers by the rotor. The first miscella draining from the rotor is pumped through the second stage heater and sprinkled onto the surface of the solid material which has been processed once. The second miscella draining from the rotor is pumped through the third stage heater and sprinkled on the dry unprocessed solid material. The final miscella draining from the rotor is collected in the final miscella tank. The flow of solvent and solid material is countercurrent. 87

Armfield Instruction Manual

Configuration for three stage continuous countercurrent extraction

Procedure Start Up Check that the UOP4 MkII is switched off, all switches are set to off and all rotary controls are set to minimum on the front panel of the console. Fill the fresh solvent tank with clean water. Fill collection troughs one (right-hand side) and two (middle) to 20mm depth by pouring water through the mesh at the base of the rotor. Pour water into collection trough three (left-hand trough) until the water drains through the pipework into the final miscella tank. Set the speed of pump one to maximum to purge air from the first stage of the process. When water drips from the first sprinkler bar stop the pump. Set the speed of pump two to maximum to purge air from the second stage of the process. When water drips from the second sprinkler bar stop the pump. Set the speed of pump three to maximum to purge air from the third stage of the process. When water drips from the third sprinkler bar stop the pump. After priming it may be necessary to top up the level of water in the first and second troughs to return them to 20mm depth. Note: the final trough will always run empty. Once the system has been primed the three pumps can be switched on and adjusted to run at the desired solvent flow rate (typically setting 4.0 on the speed controls). The solvent stage system should now be taking liquid from the fresh solvent tank, cascading it through the three stages via the three pumps and troughs and then draining it into the final miscella tank.

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Exercise E After the system has been running for a while any imbalance in the stages will be indicated by a change in level in the first and/or second stage collection troughs. Check the right-hand trough (stage 1) first. If the level is falling reduce the speed of pump two. If the level is rising increase the speed of pump two. Now check the middle trough (stage 2). If the level is falling reduce the speed of pump three. If the level is rising increase the speed of pump three. Do not adjust the speed of pump one during the exercise. It will be necessary to check the levels at regular intervals and to make small adjustments when required. Adjust the set point of controllers 1, 2 and 3 to match the temperature indicated on the corresponding display (to avoid excessive overshoot when heating is required). Start the rotor cell and adjust the speed control to give the required rotational speed (typically 5.0 on the speed control, approximately 2 revs per hour). Put some untreated solid carrier in the hopper of the spiral material feeder. Turn on the spiral material feeder and adjust the speed control to give the required depth of material in the cells of the rotor (typically 30 - 50% full). When the solid material reaches the aperture in the base at the rear of the extractor it will be necessary to turn on the spray nozzle so that the material is washed into the extracted solids tank. Adjust the position of the nozzle and pressure regulator as required to prevent overspray. Note: It may be necessary to refill the hopper with solid carrier until the system has stabilised and extraction can commence. Allow the cells of the rotor to fill with untreated solid carrier. When the dry material passes beneath the sprinkler bars it may be necessary to make small adjustments to pump two and pump three to maintain the correct levels in the troughs. Measure and record the temperature TS of the solvent direct from the fresh solvent tank indicated on the stage 1 temperature controller (T1) before the heater is switched on. Once the system has settled down and the solvent stages are running in balance switch on heater one then adjust the set point on temperature controllers one to 40oC. When T1 has stabilised switch on heater two then adjust the set point on temperature controller 2 to 40°C. When T2 has stabilised switch on heater three then adjust the set point on temperature controller 3 to 40°C Note that no heater should be switched on until there is a steady flow of liquid through the heater. Monitor temperatures T1, T2 and T3 (indicated on the appropriate temperature controller) and wait until the temperatures have stabilised. When the temperatures have stabilised the extraction can commence as follows.

Extraction Before commencing the extraction it will be necessary to organise recording of the required data. The following readings will be required to show the transient response as the system stabilises: T1 Temperature of solvent entering the first cell of the rotor T2 Temperature of first miscella entering the second cell of the rotor

89

Armfield Instruction Manual T3 Temperature of second miscella entering the third cell of the rotor T4

Temperature of final miscella leaving the third cell

C1 Conductivity of solvent entering the first cell of the rotor (will remain constant) C2 Conductivity of first miscella entering the second cell of the rotor C3 Conductivity of second miscella entering the third cell of the rotor C4 Conductivity of final miscella leaving the third cell In manual operation it will be necessary to switch the multi function display on the console between C1, C2, C3, C4 and T4 in order to take down these readings on a regular basis (typically once per minute) as the process progresses. T1, T2 and T3 are indicated continuously on the appropriate temperature controllers. Allow the hopper to empty of untreated Porosolid carrier then fill the fill the hopper with solid carrier containing the KHCO 3 just as the untreated solid carrier runs out.. Start the stopwatch when the hopper is filled. Note: It will be necessary to refill the hopper with treated solid carrier as the exercise proceeds. As the solvent extracts the Potassium Bicarbonate from the solid carrier the outputs from conductivity probes C2, C3 and C4 will rise and eventually stabilise. Once the system has reached a steady state the appropriate temperatures and the conductivities can be recorded. Note: When the system has achieved steady state small cyclic variations will be observed in the readings from conductivity probes C2, C3 and C4 as the individual cells of the rotor present fresh solid material to the solvent stream. This effect can be observed more clearly when logging results continuously using the optional PC logging interface and software (Armfield product code UOP4MkII-303IFD). Readings at steady state Once the system has reached steady state the following measurements should be recorded: Feeder speed setting

NF

%

Rotor speed setting

NR

%

Pump 1 speed setting

N1

%

Pump 2 speed setting

N2

%

Pump 3 speed setting

N3

%

Temperature of solvent at stage 1

T1

o

Temperature of solvent at stage 2

T2

o

90

C C

Exercise E

Temperature of solvent at stage 3

T3

o

Temperature of final miscella

T4

o

Conductivity of solvent at stage 1

C1

mS

Conductivity of solvent at stage 2

C2

mS

Conductivity of solvent at stage 3

C3

mS

Conductivity of final miscella

C4

mS

C C

Using a measuring cylinder and stopwatch collect a timed sample of the final miscella to determine the flowrate of solvent leaving the process (F4 litres/hr). When shutting down the process switch off the heater before the solvent pump. If time permits the exercise can be repeated at different solvent flow rates, or solvent temperatures to investigate their effect on the rate of extraction and the efficiency of the process. Similarly, the effect of the solid feed rate and/or the rotor speed can be investigated.

Presentation of Results and Analysis From the measurements taken while the process was stabilising calculate the concentration of the KHCO 3 in the first miscella, second miscella and final miscella by converting the readings of C2 – C1 with T2, C3 – C1 with T3 and C4 – C1 with T4 into values of percentage weight KHCO 3 (using the conversion graphs in Graphs of Concentration). Plot the graph of percentage weight of extracted material in the first miscella, second miscella and final miscella against time. Comment on the shape of the graphs as the process stabilises. What is the contribution of each stage in the process? Using the calibration graphs for the equipment where appropriate (refer to Operational Procedures for details) convert the above measurements taken at steady state as follows: Mass Flowrate of solid material (From NF using calibration graph)

MS

kg/hr

Mass Flowrate of solvent entering the process (from N1 using calibration graph)

M1

kg/hr

Mass Flowrate of final miscella (= F4 x density  of the M4 solvent)

kg/hr

Loss of solvent in the process (= M1 – M4)

kg/hr

ML

Concentration of KHCO 3 in the solid (from preparation ConcS data)

%wt

91

Armfield Instruction Manual

Input of KHCO 3 to the process (= MS x ConcS/100)

MI

kg/hr

Concentration of KHCO 3 in the first miscella (from C2 – Conc2 C1 and T2 using graph)

kg/hr

Concentration of KHCO 3 in the second miscella (from C3 – C1 and T3 using graph)

kg/hr

Conc3

Concentration of KHCO 3 in the final miscella (from C4 Conc4 – C1 and T4 using graph)

%wt

Output of KHCO 3 from the process (=M1 x Conc4/100) MO

kg/hr

Percentage of KHCO 3 extracted from the solids (= 100  x MO/MI)

%

Energy input to stage 1 of the process (primarily heating of the solvent) (= 0.277 x M1 x (T1 – TS) x Cp)

Q1

Watts

Q2

Watts

Q3

Watts

Qt

Watts

Note factor of 0.2777 for M1 in kg/hr and Cp in kJ/kg/K Energy input to stage 2 of the process (primarily heating of the solvent) (= 0.277 x M2 x (T2 – T4) x Cp) Note factor of 0.2777 for M2 in kg/hr and Cp in kJ/kg/K. Note temperature of fluid entering the second stage heater cannot be directly measured and T4 is taken to be equivalent temperature. Energy input to stage 3 of the process (primarily heating of the solvent) (= 0.277 x M3 x (T3 – T4) x Cp) Note factor of 0.2777 for M3 in kg/hr and Cp in kJ/kg/K. Note temperature of fluid entering the third stage heater cannot be directly measured and T4 is taken to be equivalent temperature. Total energy input to process(= Q1 + Q2 + Q3)

Comment on the efficiency of the process by considering the magnitude of the calculated values obtained when the process has achieved steady state (the appropriate parameters are suggested in the Theory section above). Compare the results obtained with those for single stage extraction (Exercise C) and two-stage extraction (Exercise D). Comment on the effect of the third stage in the process. If results were taken under different operating conditions compare the results and comment on the effect of the changes on the efficiency of the process.

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Project Work For simplicity in operation the following trials can be performed using the open loop batch arrangement as described in Exercise A or the single stage continuous arrangement as described in Exercise C.

Investigate the Effect of Temperature Repeat extractions at different solvent temperature but fixed solvent flow rate (also solid feed rate if continuous operation) to establish the effect on the rate of extraction. Plot a graph of extraction rate against temperature to determine the optimum temperature for extraction. (Remember: increased temperature means increased operating costs and possible damage to the product being extracted.)

Investigate the Effect of Solvent Flowrate Repeat extractions at different solvent flowrates but fixed temperature (also fixed solid feed rate if continuous operation) to establish the effect on the rate of extraction. Plot a graph of extraction rate against flowrate to determine the optimum flowrate for extraction. (Remember: reduction in flowrate will give increased concentration but reduced throughput.)

Investigate the Effect of Solid Feed Rate (only continuous operation) Repeat extractions at different solid feed rates but fixed temperature and solvent flowrate to establish the effect on the rate of extraction. Plot a graph of extraction rate against feed rate to determine the optimum feed rate for extraction. (Remember: partial extraction from a solid requires more throughput of solid and therefore increased cost for the same gain.)

Investigate the Effect of Co-Current Flow of Solids and Liquids The quick release fittings and flexible tubing used on the UOP4 MkII will allow the pumps, sprinkler bars and solvent collection troughs to be reconnected so that the movement of the solvent is in the same direction as the solids (co-current operation). The results can be compared with those obtained in counter-current operation to demonstrate the effect of direction. As described in the teaching exercises there are many parameters which will affect the efficient operation of a solid liquid extraction process, some of which are listed above as individual project work. The effect of changing these parameters and their effects when combined can be investigated by performing a series of trials while varying each parameter in turn then changing parameters in combination.

Using Alternative Solids Solid materials other than porous pellets / Potassium Bicarbonate can be used in the UOP4 MkII provided that they are compatible with the equipment. When using porous polymer pellets prepared with salts other than Potassium Bicarbonate it will be necessary to investigate the dependence of concentration on conductivity and temperature. When using solid carrier other than the porous polymer pellets supplied by Armfield, it will be necessary to use the batch extraction vessel unless the material is suitable for use in the feeder and rotor cell. Hard materials, large particles or dusty material 93

Armfield Instruction Manual MUST NOT be fed through the spiral feeder or extraction cell as these may damage the equipment.

Investigate the Effect of Preparation of the Solid Feed Before performing solid/liquid extraction the solid material must be prepared by crushing, grinding or cutting, as appropriate, to allow adequate contact between the solvent and the soluble component. The amount of preparation will depend on the amount and distribution of the soluble component within the solid and the nature of the solid (how easily diffusion can occur). The effect of such preparation can be investigated by comparing extractions under the same conditions of flowrate and temperature but different degrees of preparation, eg. the extract from roast coffee beans ground to different grain sizes can be compared using a colorimeter to measure the change in tint.

Using Alternative Solvents (must be water based) Alternative solvents can be evaluated in the system provided that they are compatible with the materials of construction, namely PVC, Acrylic and Polypropylene. The solvents used must not be flammable or hazardous to the operator. A typical solvent would be a 10% mixture of Ethanol and water. Where the change in conductivity is small an alternative means of checking the extraction will be necessary, eg. using a refractometer.

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Contact Details for Further Information Main Office:

Armfield Limited Bridge House West Street Ringwood Hampshire England BH24 1DY Tel: +44 (0)1425 478781 Fax: +44 (0)1425 470916 Email: [email protected] [email protected] Web: http://www.armfield.co.uk

US Office:

Armfield Inc. 436 West Commodore Blvd (#2) Jackson, NJ 08527 Tel: (732) 928 3332 Fax: (732) 928 3542 Email: [email protected]

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