065_tsp Qjp400generalkiln Audit 20-08-07

ATC REPORT Activity:

AUDIT/PROCESS

CHINA / QUJIANG 3# KILN AUDIT by Jean Luc Josse & Looi Wan Leong & Wang Xiaohui

ATC, (16~20 July 2007)

Distribution Region BU Plant ATC

S. Urhan, JS Lee, RdeBelmont

Other Codification

TSP/QJP400GENERAL/Kiln Audit /20-08-07

TABLE OF CONTENTS A.

B.

EXECUTIVE SUMMARY..................................................................................3 A.1.

Safety issues.............................................................................................................3

A.2.

Main Operating Parameters......................................................................................3

A.3.

High False air inleakage...........................................................................................4

A.4.

High fluctuation in Kiln slurry feed rate.....................................................................5

A.5.

High CO formation....................................................................................................5

A.6.

Poor cooler performance..........................................................................................6

A.7.

High Heat consumption.............................................................................................6

MAIN REPORT..............................................................................................9 B.1.

Introduction...............................................................................................................9

B.2.

Work Done................................................................................................................9

B.3.

Analysis / Argument / Conclusions.........................................................................10

B.3.1.

Safety issues...................................................................................................10

B.3.2.

High fluctuation in Kiln slurry feeding rate.......................................................10

B.3.3.

High False air inleakage..................................................................................14

B.3.4.

High CO formation...........................................................................................18

B.3.5.

Poor cooler performances...............................................................................22

B.3.6.

High heat consumption....................................................................................24

B.4.

Ways to Implement.................................................................................................27

B.5.

Acknowledgements.................................................................................................30

B.6.

References..............................................................................................................30

B.7.

Appendices.............................................................................................................31

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A. EXECUTIVE SUMMARY Objective(s) QJP kiln 3# audit was conducted from 16~20 July 2007 by three ATC process engineers, JL Josse, WXH and LWL. The objectives of the kiln audit are to determine the baffling factors and to identify the bottlenecks in kiln system. Results / Findings There is a lot of room for improvement. We recommend a WR to be signed for 2008 to address all the opportunities reported below. The main process issues are : kiln feeding instability, high inleakage, poor cooler performance, overburning (low free lime) and high CO in precalciner. Four main recommendations are : reduce inleakage and primary air, install 30t capacity surge bin to feed the kiln, increase clinker bed depth and increase fan efficiency from @40% to 65%. Dewatering should be further investigated. A.1. Safety issues 1. There was no CO safety interlocking for kiln EP due to the gas analyzer at the kiln inlet EP was malfunctioned. The risk of EP explosion is high (CO @ 2375 ppm). 2. Electric cables lying on the ground floor beside the kiln shell cooling fans. 3. No safety protection screens on cooler bleed air damper, hot gas to coal mill gas duct and on the cooling fan 2 dampers. A.2. Main Operating Parameters Main parameters

Current

Expected

Remark

Kiln feed

89 tph

Important fluctuations (+/-17tph)

Clinker Production

45.9 tph or 1100 tpd

not checked, PLC data

% false air at stack (C2 outlet to Kiln EP outlet)

55.7 % of stack flow is false air

30 % false air

Specific heat consumption (SHC)

1063 kCal /kgck (not checked: based on PLC)

976 kCal /kgck

- 87 kCal/kg ck reduction expected from the differents actions

KWh/ton ck (kiln line only)

66.8 kWh/tck

50 kWh/t ck

Reduction of 25.7 % inleakage. Increasing fan efficiencies to 65%

Average free lime

0.46 %

Clinker C3S average

49.29

Cooler “k” factor

0.9

1.5 % 60 1.15

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17kcal/kgck and reduction expected.

@8kWh/tck

25 kCal / kgck reduction Higher SHC but better quality ck 39.9 kCal/kgck reduction

The plant can not increase production because the EP fan operates at 100% because of high false air inleakage (more than 55% of the gas at EP outlet). ID fan already operates at positive pressure at its outlet. Kiln is operating with high CO gas. High fluctuation of kiln feed was also a bottleneck as it affects the margin operator shall take to control operation during push of feeding. High CO formation was a big concern in the kiln system. All the bottlenecks/bafflings identified in the kiln system are described below: A.3. High False air inleakage Main false air inleakage are shown on the schematic diagram below: 1.9% false air 8.3% O2 SO2

27.5% false air

11.9 % O2

0.5% false air

29.6% false air

3 % O2 2.9 % O2

11.7 % O2

1.9 % false air

Location: Outlet

7 % O2

30.7% false air

False air (%, based on equipment outlet)

8 % O2

False air (Nm3/h, based on calculation value)

PH C2 cyclone

Outlet Gas flow (Nm3/h, based on calculation value) 82522

PH C1 cyclone

0.5%

440

82962

Dry-crusher inlet

27.5%

22851

105813

Dryer crusher outlet

30.7%

32540

138353

PH SO 2 outlet

1.9%

2624

140977

Kiln EP inlet

29.6%

41692

182669

Kiln EP outlet

1.9%

3431

186100

Total

55.7%

103578

186100

For every 1 % of false air reduction, the savings of EP fan and ID fan power consumption were estimated to be approximately 3.16 kWh and 18.9 kWh. These figures are equivalent to a saving of 0.48 kWh/ton of clinker. By targeting “only” 30 % false air (based on EP

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outlet), the savings would be as high as >8kWh/tck. This would help reduce the very excessive power consumption of the burning line 9>66kWh/tck according to MMP). In 2006, ID Fan outlet O2 was “only” 9.0% to 9.6% vs. 11.6% in 2007. The situation has worsened. Fan Efficiency:

The Fans’ efficiency of #3 Kiln ID Fan, ESP Fan is 44%, 41%. The Impact would be 8-9 kW/tck by rising to standard 65% figure. The analysis of the Fan Efficiency and Mechanical check on the Fans should be given in order to formulate an action plan to improve the performance to reduce the overall power consumption of the plant (see QJP PC investigation study in 2006). Positive pressure at Kiln ID fan outlet ID fan was running at 45 % 5 years ago. Currently, ID fan operates at 58 %. As the result of this, EP fan has to run at 100 % speed. When the ID fan speed was 45 %, the kiln might be operating at only 25.7 % of system false air inleakage 5 years ago. Therefore, it is recommended to the plant to reduce the false air inleakage to 30 %. The positive pressure at the ID fan outlet can then be eliminated, helping also for CO control (see below). A.4. High fluctuation in Kiln slurry feed rate It was observed the kiln slurry feed was fluctuating from 70 tph to 104 tph. Because of the high fluctuation in kiln feed rate, the kiln has been operating with: 1. C2 cyclone bottom temperature fluctuating from 812 deg C to 879 deg C. 2. C2 cyclone outlet temperature fluctuating from 850 deg C to 952 deg C. 3. Big variation in C1 outlet CO gas. Please refer to Table 2. 4. SO2 dedusting cyclone outlet gas pressure fluctuating from – 55 mbar to -59 mbar. 5. C2 cyclone bottom calcination degree fluctuating from 57.37 % to 87.35 %. It was observed that the calciner coal feeder automatic control loop could not be used to control the high fluctuation of C2 outlet gas and material temperature and high fluctuation of CO gas. The plant have been operating with fixed coal feed rate most of the time. A.5. High CO formation CO gas came from preheater tower although residence time is 2.6s. The most probable causes of high CO formation in the kiln system were (burner design yet to be checked): 1. High variation of the kiln feed resulting into sudden increase of differential pressure in dryer crusher. Both affecting the O2 content in the precalciner. 2. High usage of pre-calciner coal fuel rate at 6 tph due to low tertiary air temperature and high false air inleakage and important variation in the precalciner temperature.

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3. The fine coal is already fine (8.8 % at 90 microns. VM is 25%). It may result into injection fluctuation. It also dangerous from a risk fire point of view in coal mill circuit  trials are recommended with coarser coal (10-12%). 4. Low tertiary air temperature (730C dropped down by -100C to 630C across the TA duct) A.6. Poor cooler performance Main Parameter

Operating

Expected

Cooler Efficiency

55 %

65

Cooler recovery “k” factor

0.9

>1.15

Clinker temperature (assume)

1460 deg C (not checked)

Cold Clinker temperature

210 deg C

Cooling fan air flow

2.53 Nm3/kg cl

Tertiary air temperature

duct

inlet 730 deg C (up to 100 deg 850 deg C C difference at outlet)

Secondary air temperature

730 deg C

Tertiary air flow

0.65 Nm3/kg cl

Exhaust air flow

1.54 Nm3/kg cl

Secondary air flow

0.27 Nm3/kg cl

Hot gas to coal mill

0.08 Nm3/kg cl

>850 deg C

The overall efficiency of the cooler was considered very poor (standard grate cooler). A.7. High Heat consumption Due to high false air, high primary air, CO formation, overburning, excessive fluctuation in the kiln system, kiln is currently operating at high heat consumption (1068 kCal/kg cl).

Elimination of false air from C2 cyclone to SO 2 cyclone outlet (ref: 30 % system inleakage) Cooler efficiency Elimination of 21.1 % PA in Kiln burner pipe (ref: 15 % PA)

Current

Expected

SHC reduction

55.7 %

30 %

14.6 kCal/kg cl

0.9

1.15

39.9 kcal/kgck

36.1 %

15 %

17.6 kcal/kg

20%

10% ?

0.46 %

1.5 %

High PH exit temperature due to fluctuation Reduction of moisture content Free lime

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15 kcal/kgck

Emergency Actions To quickly install back the CO safety interlocking system for Kiln EP. Table of actions This table of actions lists recommendations that have been identified by plant and ATC representatives during the audit (See more-detailed one with ways for implementation at the end of the document) No.

Action

Priority

1

Prevent safety accident

Safety

To quickly repair kiln EP inlet gas analyzer in order to restore the CO gas safety interlocking. 2

3

To reduce false air from 55.7 to 30% of EP outlet to reduce SHC by 14.6 kCal/kg cl and 8.16 kWh/ton cl To reduce primary air from 36% to 15% as to reduce SHC by 17.6 kCal /kg cl by adjusting axial and radial air dampers.

1

To consider redesigning the burner if adjusting axial air and radial air flow is unsuccessful.

2

Improve kiln slurry feeding stdev from 5tph to 1tph to stabilize operation and increase production To make the two slurry feeders’ vacuum filters to discharge slurry separately according to timing. To allow the weighting belt speed changeable. To revive the automatic control of the kiln feeding system. To consider installing an intermediate bin to better control the kiln slurry feed : strongly recommended option. Refer to Holcim India plant : MADUKKARAI Plant ATC to investigate if other installations in the world have similar problems.

4

5

1 1 1 1 2

To eliminate CO gas formation in precalciner To re-activate the calciner coal feeder automatic control.

1

To reactivate the pressure meter of coal conveying system.

1

ATC engineers will investigate the calciner coal burner, coal injection and the design of calciner. Plant to investigate coal quality fluctuation

2

Reduce overburning

1

To train Operator in kiln operations+ proper instrumentation.

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6

Optimize cooler operation by increasing recovery “k: factor from 0.9 to 1.15 as to reduce SHC 39.9 kCal/kgck. To optimize secondary air and tertiary air temperature to 850 deg C by increasing the theoretical clinker bed thickness from 350 mm to 450 mm. This can be done by reducing cooler grate speed from 9 stroke/min to 7 stroke/min.

1

To consider installing fixed cooler plate.

2

To reset kiln hood pressure to -0.1mbar and to re-activate automatic control between kiln hood pressure and cooler EP fan.

1

To install a clinker temperature monitoring system so that kiln operator can monitor the clinker temperature.

2

To adjust blowing profile according to recommended pattern 7

Reduce water content Other similar dewatering system plant manage to reduce water content down to 10% . To be investigated. Refer to Holcim India plant : MADUKKARAI Plant.

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1 2

B. MAIN REPORT B.1. Introduction QJP kiln 3# audit was conducted from 16~20 July 2007 by three ATC process engineers, JL Josse, WXH and LWL. The objectives of the kiln audit are to determine the baffling factors and to identify the bottlenecks in kiln system. The one-week mission was carried out with the great co-operation & enthusiasm from the plant management and the plant team.

B.2. Work Done In the mission we carried out measurements such as air flow volume, static and dynamic pressure, temperature and gas compositions of the kiln system. We also measured the surface temperatures of kiln, cyclones and cooler for heat balance calculation. We also visited CCR control room to collect some operating data. In the control room, we downloaded some of these data for trend analysis. We also obtained the kiln feed slurry moisture content and LOI analysis for kiln feed slurry and raw meal dust at the bottom of cyclone C2. We were not able to perform fan efficiency test due to the plant Electrical Department’s power-meter was malfunctioned. The semi-wet kiln was designed by FLS to produce 1000 tons of clinker per day. However, from our calculation based on the moisture contents of 20 % and LOI of 35.5 % retrieved from the lab analysis, the kiln was supposed to produce 1100 t/h, theoretically. Due to the high fluctuation of the kiln feed at the slurry feeder, we were not able to obtain a constant kiln slurry feed rate. The determination of the kiln feed rate was based on the average value of the data collected from the PLC. To obtain a precise clinker production, it is advisable for the plant to carry out the weighing of clinker and kiln slurry feed. However, since the objectives of the mission are to determine the bottleneck of the kiln system, the weighing has not been carried during the mission as this was not the #1 priority (as discussed with RD before going). Nevertheless, we were still managed to conduct a heat balance starting from cooler to ID fan inlet based on the following assumptions. 1. Kiln feed rate was 89 tph abstracted from the average value of PLC data. 2. Clinker factor was 1.94. 3. Kiln and calciner coal feed rate were 2.6 tph and 6.0 tph, respectively, abstracted from the average values of PLC data. 4. Coal LHV was 5757 kCal/kg coal (given by the plant). 5. Minimum combustion air rate was 1.1631 Nm3/1000 kCal of coal combustion. 6. Minimum combustion air rate at kiln and calciner were 0.379 Nm3/kg clinker and 0.875 Nm3/kg clinker. 7. Coal combustion products:

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a) Carbon dioxide gas produced was 0.2077 Nm3 / 1000 kCal of coal combustion b) H2O gas produced was 0.0695 Nm3 / 1000 kCal of coal combustion c) Nitrogen gas was 0.9235 Nm3 / 1000 kCal of coal combustion 8. Hot Clinker temperature was 1460 deg C. 9. Preheater exit dust load was 0.1 kg / kg clinker 10. Kiln backend false air inlekage was 0.07 Nm3/kg clinker. 11. Water spray inside dryer crusher was 2 tph. In Appendix, Table 3 shows the description of main equipment and its design data. Table 4 shows the main kiln operating data during the mission and Figure 1 shows the process data of the kiln system. B.3. Analysis / Argument / Conclusions In the mission, we were able to identify the bottlenecks of the kiln system. The bottlenecks are described below: B.3.1.

Safety issues

There were some critical safety issues with the plant. 1. There was no CO safety interlocking for kiln EP due to the gas analyzer at the kiln inlet EP was malfunctioned. The risk of EP explosion is very high as based on our measurement; the CO content at the kiln EP inlet has reached up to 2375 ppm. 2. It was seen that there were a lot of electric cables lying on the ground floor beside the kiln shell cooling fans. The cables were actually exposed to rain. The cables pose very high risk of electric shocks at the site. 3. There was no safety railing around the measuring point at the kiln outlet EP. 4. There were no safety protection screens on the bleed air dampers of cooler exhaust gas duct and hot gas to coal mill gas duct. 5. There was no safety protection screen on the cooling fan 2 dampers. B.3.2.

High fluctuation in Kiln slurry feeding rate

It was observed the kiln slurry feed was fluctuating from 70 tph to 104 tph. The fluctuation was confirmed from the data we have collected from the PLC. The trend curve of the kiln slurry feed against time is shown in Chart 1. Using statistical analysis method on the data from PLC, the average and standard deviation of the kiln slurry feed were 89 tph and 5 tph, respectively. The feeder precision only reached 21% (dry line’s recommended figure should be2s. Hence, too short

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residence time is not a direct cause for bad combustion. Obviously, less inleakage would increase even more the residence time. There are enough time and enough O2 for combustion. However, as already mentioned, the fluctuating and low tertiary air temperature (@650C at precalciner inlet) affects the quality and the speed of the ignition of the combustion. Coal preparation and injection Coal finely ground (8.8%R80, finer than the recommended figure for a 25% VM coal). Too fine coal may create fluctuation in the injection. However it is not always the case. The design of the precalciner burner has not been studied yet. The primary air seems to be OK. The quality of coal shall also be further investigated. Impact of high inleakage Although false air brings O2 for the combustion, it has an overall negative impact on the combustion quality for the following reasons :  The O2 may not be located where it is required  The false air have to be heated, requiring more fuel and as a consequence more O2, hence reducing the overall residence time in the precalciner.  Build up formation that affects the flow pattern Overall instability of the system and IDFan outlet underpressure Observing the trends and commun understanding indicate that CO generation is obviously clearly affected by the huge fluctuation of the kiln feeding. However shall be the other factors, important variation in the kiln feeding affects all the dynamics inside the precalciner and as a result the combustion. Addressing these fluctuations is the main factor to reduce CO. A standard way to smooth those variation is to keep the IDFan outlet pressure under control, slightly in succion (around -1mbar). This is not the case in QJP (see next topic). Positive pressure at Kiln ID fan outlet Based on our measurement, the static pressure at the kiln EP inlet was at positive 3.2 mbar even though kiln EP fan damper and EP fan speed have run up to 100 %. It was observed that the kiln ID fan speed was operating at 58 %. We were told by the plant personnel that ID fan speed was normally at 40 to 45 % 5 years ago. The air flow at ID fan was measured to be 140,985 Nm3/hr. The ID fan speed was set at 58 %.

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Using Fan Law Theory, ID fan at speed of 45 % would be operating at 109,394 Nm3/hr of air flow. The reduction of air flow of 31,591 m3/hr is equivalent to 30.5 % reduction of total system false air of 103,278 Nm3/hr. This could explain that the kiln might be operating at only 25.7 % of system false air inleakage 5 years ago. Therefore, it is recommended to the plant to reduce the false air inleakage to 30 % at this moment. The positive pressure at the ID fan outlet can then be eliminated. Other factor It was also calculated that the kiln hood cross velocity was high at 11.7m/s. The recommended figure was 6 m/s. This high velocity air might affect the stability of flame and even might cause high refractory wear rate at kiln nosering and burner pipe.

 Hence the most probable causes of high CO formation in the kiln system were: 1. High variation of the kiln feed affecting all the gas flow of the line 2. High false air inleakage in preheater system which has been discussed earlier. 3. High usage of pre-calciner coal fuel rate due to low temperature tertiary air and high inleakage. 4. Coal fineness of 8.8 % could be too fine. 5. The design of the installation should be checked with more details (inc. burner). 6. Lack of control of ID fan outlet pressure because of excessive inleakage Reminder of 2006 observations : Items

Target/Normal

Existing status

Evaluation

~ 2.0s（Ｎｏｒｍ

@3.0s

OK

Uniform and reasonable.

PC upper is higher than middle and bottom; huge variations--- Max 98℃ between two points at same level.

Bad

Stable ±5℃

Max. 24℃

Bad

CO kiln exit

10000

1.4-2.0

3500-6250

C2 Cyclone exit

1.7-2.2

3264-3816

The Dry-crusher exit

7.9-8.1

2824-3004

The ID fan inlet

9.5-9.6

1587-2830

PC exit

C2 Cyclone exit Kiln Feed: 65-70t/h (R/C=1.87) 18-July-2006 10:40 - 12:00 1

2

3

A(PC Inlet)

867-870

918-930

B(PC Cone)

790-806

808-818

813-817

C(PC Middle)

835-846

817-820

878-881

D(PC Upside)

835

875-886

894

PC exit

865-872

C2 Cyclone exit

861-904

O2 (%)

CO ppm

No indication

> 10000

0.8-1.2

275-1270

C2 Cyclone exit

0.5-0.9

2257-5171

The Dry-crusher exit

7.1-7.2

4012-4612

The ID fan inlet

8.4-8.5

4882-5771

PC exit

Kiln Feed: 75-80t/h (R/C=1.87) 20-July-2006 9:30 - 10:40 1

2

A(PC Inlet)

949

904

B(PC Cone)

891

833

C(PC Middle)

832

D(PC Upside)

838

PC exit

938

C2 Cyclone exit

839

B.3.5.

3

O2 (%)

CO ppm

Kiln inlet

0.3-0.4

5200-7800

797

PC exit

1.5-3.2

2203-2014

843

849

C2 Cyclone exit

2.8-4.2

2623-1892

936

886

The Dry-crusher exit

8.7-9.2

288-292

The ID fan inlet

9.1-9.3

2535-2378

Poor cooler performances

The cooler outlet clinker temperature was 210 deg C and cooler cooling fan air flow was 2.53 Nm3/kg ck (28 deg C). Tertiary air flow was 0.6463 Nm3/kg ck (730 deg C). The exhaust air flow (270 deg C) and hot gas to coal mill (490 deg C) air flow were 1.5427 Nm3/kg ck and 0.0772 Nm3/kg ck, respectively. The secondary air flow was calculated to be 0.2698Nm3 / kg ck at 730 deg C.

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Based on the measurement above, the cooler efficiency and recovery “k” factor were evaluated to be 56% and 0.9, respectively. The overall efficiency of the cooler was considered poor. We were not able to see the interior of cooler to check for the red river. However, considering the high amount of cooling air volume and clinker outlet discharge temperature of 210 deg C, there is a likelihood of red river inside the cooler. Further investigation to install inspection door for inspection. From our calculation, based on the same amount of cooling air flow, it was possible to increase cooler efficiency to 65 % with heat recovery ratio of 1.15 by increasing tertiary air and secondary air temperature to 850 deg C and reducing clinker outlet temperature to 110 deg C. This could be done by regulating the speed of cooler. We recommend that the plant start by reducing the speed from 9 stroke / min to 7 stroke / min. Further optimization of cooler is required to obtain good cooler efficiency. It is also possible to increase the cooler efficiency by installing fixed plates at the cooler inlet. By increasing the temperature of secondary and tertiary air temperature from 730 deg C to 850 deg C (assuming with same air flow), it is possible to gain additional heat of 39.9 kCal/kg cl. The chart of cooler cooling air blowing density along the cooler is shown in Chart 12. Chart 12Cooler Blowing Density

From the chart above, we can see that the cooling air flow at chamber 1 and 2 was too high. This could explain why the tertiary air and secondary air temperature were low at 730 deg C. Hence this has affected good recuperation of heat from the cooler. From the chart,

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we can see that the most probable reason for high cooler outlet clinker temperature was due to cooling air flow at chamber 3 and 4 were lower than recommended air flow. In the mission, the grate speed was measured at 9 stroke/min. Theoretically the clinker bed thickness is calculated to be 350 mm. In order to improve heat recuperation, the grate speed should be reduced to 7 stroke/min. Theoretically, with this speed, the clinker bed thickness would be at 450 mm. It was also observed that the kiln hood pressure was always controlled at 0.0 mbar. From the control room, it was understood that the operator was actually using the cooling air fan volume flow rate to regulate the kiln hood pressure. This operating procedure is totally against the Lafarge Kiln Operating Guidelines. Furthermore the bottlenecks identified by the evaluation tool were included cooler EP and EP fan which have deficient margin when upset.

B.3.6.

High heat consumption

Due to high false air, CO formation in the kiln system, poor cooler performance, high primary air, high fluctuation of the feed rate and low free lime (ove-rburning), kiln is currently operating at high heat consumption. From our calculation, the heat loss due to:  False air (from C2 to ID fan inlet) at 58,455 Nm3/hr was 2,602,825 kCal/hr or 56.7 kCal/kg clinker. The heat loss was equivalent to 452 kg Coal /hr of energy from combustion. If the false air (from C2 to ID fan inlet), is reduced to 30 % false air, by 15,022 Nm3/hr which is 25.7 % reduction, then the heat loss would be 668,844 kCal / hr or 14.6 kCal/kg clinker.  The reduction in primary air flow would increase the intake of secondary air flow. By reducing the 21.1 % primary air would allow 3,673 Nm3/hr of secondary air intake. The increase of 3,673 Nm3/hr of secondary air would supply 806,128 kCal/hr or 17.6 kCal/kg cl of energy to the kiln. This is equivalent to reduction of 140 kg coal/hr from the kiln coal feed.  Improvement in SAT and TAT would reduce the SHC by 39.9kcal/kgck.  Stabilization of the feeding rate should help smooth the system outlet temperature variation getting the averaged figure down by @20C, affecting the SHC by  Because of the huge variation of the system, lack of proper instrumentation and process mastery, the plant produces clinker with very low free lime. In order to avoid flushes, the operator has to overburn to be able to control the variation in the level of preparation of the material entering the kiln. There are no other option at the time being.

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Hence, kiln feeding variation is really cause for overburning and in this aspect over SHC.  In addition, the plant should investigate opportunity to reduce the cake water content. For wet dry process, it has been reported reduction down to 10% of the moisture content (see Holcim, ACC LTD Madukkarai plant in India). Table of actions and recommendations This table of actions lists recommendations that have been identified by plant and ATC representatives during the audit. This table of actions has to be considered as base document for further discussion. No.

Action

Priority

1

Prevent safety accident

Safety

To quickly repair kiln EP inlet gas analyzer in order to restore the CO gas safety interlocking.

1

To install safety railing at the kiln EP fan inlet and cyclone roofs measurement point platform. To install safety protection screens on the bleed air dampers of cooler exhaust gas duct and hot gas to coal mill gas duct. To reinstall cables which were found lying on the ground floor beside the kiln shell cooling fan to above the ground with proper electrical conduit. 2

To reduce false air from 55.7 to 30% of EP outlet to reduce SHC by 14.6 kCal/kg cl and 8.16 kWh/ton cl

1

To repair and seal the false air inleakage at the 2 inspection doors on dedusting cyclone SO2. To further investigate the cause of high false air inleakage at the duct of C1 to dry-crusher inlet during shutdown. To further investigate the cause of high false air at dryer crusher. To further investigate the cause of high false air inleakage from SO2 cyclone outlet to Kiln EP inlet. To repair and seal the gap of the kiln hood main door. To reduce primary air from 36% to 15% as to reduce SHC by 17.6 kCal /kg cl by adjusting axial and radial air dampers. To consider redesigning the burner if adjusting axial air and radial air flow is unsuccessful. 3

Improve kiln slurry feeding stdev from 5tph to 1tph to stabilize

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1

operation and increase production and reduce SHC To make the two slurry feeders’ vacuum filters to discharge slurry separately according to timing. To allow the weighting belt speed changeable. To revive the automatic control of the kiln feeding system. To regularly clean up the accumulation of materials on the belt weigher. To install a chain scraper under the belt conveyor to clean up the spillage before the rotary feeder. To consider installing an intermediate bin to better control the kiln slurry feed: strongly recommended option To install measuring point at the SO 2 bottom discharge point. ATC to investigate if other installation in the world have similar problems. 4

To eliminate CO gas formation.

1

To re-activate the calciner coal feeder automatic control. To further investigate on how to eliminate the sudden increase of differential pressure inside dryer crusher during shutdown. To increase cooler efficiency to recovery “k” factor of 1.15. To reactivate the pressure meter of coal conveying system. Trial with coal fineness @10% ATC engineers will investigate the calciner coal burner, coal injection and the design of calciner. 5

Reduce overburning

1

To train Operator in kiln operations. To reduce kiln feed fluctuation To get proper instrumentation 6

Optimize cooler operation by increasing recovery “k: factor from 0.9 to 1.15 as to reduce SHC 39.9 kCal/kg cl. To optimize secondary air and tertiary air temperature to 850 deg C by increasing the theoretical clinker bed thickness from 350 mm to 450 mm. This can be done by reducing cooler grate speed from 9 stroke/min to 7 stroke/min. To consider installing fixed cooler plate. Plant has to try to obtain an optimum undergrate pressure

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2

To reset kiln hood pressure to -0.2mbar. To re-activate automatic control between kiln hood pressure and cooler EP fan. To install a clinker temperature monitoring system so that kiln operator can monitor the clinker temperature. To repair or check the availability of the kiln hood pressure gauge. To adjust blowing profile according to recommended pattern To train Operator in kiln operations.

B.4. Ways to Implement No. 1 Action Prevent safety accident Way to implement : Followed up by Safety Manager and ATC engineers

No. 2 Action To reduce false air from 55.7% to 30% at EP outlet. Way to implement: Process inspection coordinated with maintenance. Weekly follow up of oxygen measurement after optimization. Thorough inspection of dryer crusher, gas duct expansion joints, and gas ducts from C1 cyclone to kiln EP inlet during shutdown. To install scaffolding on preheater tower to inspect gas ducts conditions. To regulate axial and radial air damper to reduce primary air flow. To consider redesigning the burner if adjusting primary air flow is unsuccessful with ATC supports.

No. 3 Action To Improve kiln slurry feeding as to stabilize operation Way to implement: Apply the priority-1 actions. Install instrumentation to better understand the causes of the lack of stability. To carry out weighing of kiln slurry feed after optimization. To consider installing an intermediate bin to better control the kiln slurry feed. To install sampling points at the SO 2 discharge point. ATC engineers will refer to other installation for detail information from Lafarge plants. And also to refer to other installation or supplier of the dryer crusher for detail information Weekly follow up of temperature and gas measurement after optimization. No. 4 of action To eliminate CO formation

Page 27 of 37

Way to implement: Weekly followed up of gas measurement after optimization. To further investigate the design of calciner coal burner, conducting a precise mapping of O2 and CO in the precalciner. To be confirmed by trial: fine coal too fine of 8.8 % at 80 micron resulting into injection fluctuation. ATC can help to define the trial protocole. After installation of the pressure gauge and connection to CCR, further investigation could be carried out on the injection system. Plant to provide drawing of the precalciner burner to ATC for further study. No. 5 of action To reduce overburning. Way to implement: reducing kiln feed fluctuation is the first step. In addition, install proper instrumentation, train operator using 10 golden rules of kiln operation and post sevilla combustion concepts. An attempt wit higher C3S could e also an option to validate the impact of clinker quality. The optimum kiln speed to feed ratio should be further investigated and a representative clinker microscopy should be completed to see the size of the remaining free lime as well as of belite and alite. Instrument

QJP Instrumentation status

Recommendations

Kiln burning zone pyrometer

No

To install pyrometer – proper maintenance and proper calibration schedule

Kiln hood pressure meter

Ok

To maintain the reliability of the pressure meter – proper calibration schedule

Tertiary air duct inlet temperature

Ok

To maintain the reliability of the thermocouple – proper calibration schedule

Tertiary air duct outlet temperature

No

To install thermocouple and to maintain the reliability of the thermocouple – proper calibration schedule

Tertiary air duct pressure meter

No

To install pressure meter

Tertiary air duct damper position opening indicator

No

To repair automatic control from PLC

Cooler clinker temperature indicator

No

To install thermocouple and to maintain the reliability of the thermocouple – proper calibration schedule

Undergrate pressure meter

Ok

To maintain the reliability of the pressure meter – proper calibration schedule

Cooler exhaut gas temperature indicator

Ok

To maintain the reliability of the thermocouple – proper calibration schedule

Hot gas to coal mill gas

No

To install thermocouple and to maintain

Page 28 of 37

temperature indicator

the reliability of the thermocouple – proper calibration schedule

Kiln shell temperature scanner

Ok

To maintain the reliability of the scanner – proper maintenance and calibration schedule

Kiln main motor current indicator

Ok

To maintain the reliability of the ammeter – proper maintenance and proper calibration schedule

Kiln speed indicator

Ok

To maintain the reliability – proper maintenance and calibration schedule

Kiln inlet temperature indicator

Ok

To maintain the reliability of the thermocouple – proper calibration schedule

Kiln inlet pressure meter

Ok

To maintain the reliability of the pressure meter – proper calibration schedule

Kiln inlet gas analyzer

Ok

To maintain the reliability of the analyzer – proper maintenance and calibration schedule

C2 cyclone bottom temperature indicator

Ok

To maintain the reliability of the thermocouple – proper calibration schedule

C2 cyclone outlet gas temperature indicator

Ok

To maintain the reliability of the thermocouple – proper calibration schedule

C1 cyclone outlet gas analyzer

No

To repair oxygen gas analyzer

Kiln Pfister coal feeder coal transport pressure meter

No

To install a digital pressure meter and link to PLC

Kiln Pfister motor current indicator

Ok

To maintain the reliability of the ammeter – proper maintenance and proper calibration schedule

Kiln Pfister weighting system

Ok

To maintain the reliability of the weighting system – proper maintenance and proper calibration schedule

Calciner Pfister coal feeder coal transport pressure

No

To install a digital pressure meter and link to PLC

Calciner Pfister motor current indicator

Ok

To maintain the reliability of the ammeter – proper maintenance and proper calibration schedule

Calciner Pfister weighting system

Ok

To maintain the reliability of the weighting system – proper maintenance and proper calibration

Page 29 of 37

schedule Calciner automatic control

No

To repair control system

Kiln primary air blower pressure indicator

No

To install digital pressure meter and link to PLC

Kiln primary air blower motor current indicator

No

To repair ammeter

No. 6 of action To optimize cooler operation to reduce SHC. Way to implement: To optimize cooler undergrate pressure by regulating the cooler speed. A step by step approach is recommended. Weekly followed up of air flow and temperature measurement of cooler system after optimization+ observation of red river. In case of red river, ATC should make recommendations accordingly B.5. Acknowledgements The 3# kiln audit mission at QUJIANG had been successfully implemented with the help and supports from the plant management especially Mr. Zhang Jinghong, Mr. Li Da Bing and Mr. Zhang Zhe Ping. B.6. References

The Heat and Mass balance of 3# kiln………………………………………

The cooler air distribution of 3# kiln………………………………………….

The false air evaluation of 3# kiln……………………………………………

The plant update study of 3# kiln……………………………………………

Mass and Heat Balance

Cooler air distribution of QJP

PH False air calculation

Plant update study of QJP

2006 report on precalciner survey

The measurement data of 3# kiln……………………………………………

Page 30 of 37

Measurement data of QJP

The cooler bed depth of 3# kiln……………………………………………..

Cooler bed depth of QJP

B.7. Appendices Table 3 Item

QJP 3# kiln main equipments basic data Unit

Designed

operating

Kiln output

t/d

996

1100

Kiln speed

rpm

3.2

3.4

Kiln main motor

kw

160

97

Main burner coal rate

t/h

1.5~5

2.9

Precalciner burner coal rate

t/h

2~8

6.0

Vacuum filter output

t/h

40×2

89

Dry-crusher output

t/h

80

PH IDF volume flow rate

M3/h

220000

PH IDF pressure

Pa

9800

PH IDF inlet damper

%

95

PH IDF speed

%

57

PH IDF main motor

kw

1000

865

Kiln EP inlet volume rate

M3/h

250000

298345

Kiln EP fan volume rate

M3/h

233730

302714

Kiln EP fan pressure

Pa

1934

Kiln EP fan main motor

kw

220

Kiln EP fan inlet damper

%

100

Kiln EP fan speed

%

100

Cooler grates area

M2

26.7

1# chamber fan volume rate

M3/h

13270

1# chamber fan pressure

Pa

7540

1# chamber fan damper

%

2# chamber fan volume rate

M3/h

35000

2# chamber fan pressure

Pa

5370

2# chamber fan damper

%

3# chamber fan volume rate

M3/h

45300

3# chamber fan pressure

Pa

2597

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23780

195

15186 100 35498 100 27898

Remark Φ3.5×54m

160℃

160℃

3# chamber fan damper

%

90

4# chamber fan volume rate

M3/h

62400

4# chamber fan pressure

Pa

1715

4# chamber fan damper

%

Inlet clinker temperature

℃

1371

Outlet clinker temperature

℃

65+ambient

Cooler EP inlet temperature

℃

200

Cooler EP inlet volume rate

M3/h

160000

Cooler EP fan inlet temperature

℃

300max.

Cooler EP fan inlet volume rate

M3/h

160800

Cooler EP fan pressure

Pa

2000

Cooler EP fan inlet damper

%

100

Cooler EP fan speed

%

74

Cooler EP fan main motor

kw

43258 75 110~210

150

155

123

Table 4 Main process operation data Item

Operation data

Item

Operation data

Slurry moister (%)

19

Slurry feeding rate(t/h)

89

Coal fineness(%, 0.08mm sieve residual)

8.8

Slurry fineness(%, sieve residual)

0.08mm

Coal fine moister (%)

1.1

Coal LHV (kcal/kg)

5726

kiln inlet temperature (℃)

996

Kiln inlet O2 (%)

6

Kiln inlet CO (ppm)

0

Kiln inlet decarbonisation (%)

Kiln inlet material temperature (℃)

843

Kiln inlet pressure (Pa)

150

C2 outlet O2 (%)

2.85

C2 outlet temperature (℃)

832

C2 outlet CO (%)

4964

C1 outlet O2 (%)

2.3

C1 outlet temperature (℃)

591

C1 outlet CO (%)

1300

C1 outlet pressure (Pa)

-2600

Dry-crusher (℃)

Dry-crusher outlet temperature (℃)

370

PH IDF inlet temperature (℃)

167

PH IDF inlet O2 (%)

10.6

PH IDF inlet CO (ppm)

1038

PH IDF inlet pressure (Pa)

-838

Kiln EP inlet temperature (℃)

169

Kiln EP inlet pressure (Pa)

320

Kiln EP inlet O2 (%)

9.6

Kiln EP inlet CO (ppm)

2375

Kiln EP fan inlet temperature (℃)

160

Kiln EP fan inlet O2 (%)

10.6

Kiln EP fan inlet CO (ppm)

1740

Page 32 of 37

inlet

material

temperature

79

543

Cooler outlet gas temperature (℃)

270

Clinker temperature in cooler outlet (℃)

Page 33 of 37

210

unit

SO2 to ID fan

C2 to C1 gas duct

Pst

mbar

T

161 C

CO

167 C

T

710 CC

CO

5300

CO

ppm

Pst

-60

NOx

167 C

Pst

-16.5

NOx

1013

NOx

ppm

O2

8.3%

O2

2.9%

Chart13 QJP Process Measurement

SO2 from crusher T

200 C

CO

3836

Pst

-48

NOx

585

O2

C2 outlet gas duct

8.4%

T

832C

CO

4964

Pst

-13.9

NOx

855

O2

2.9%

C1 outlet gas duct T

591 C

CO

1300

Pst

-26

NOx

850

O2

3%

T

Dust return

EP outlet 161 C

CO

1740

Pst

- 8.38

NOx

456

O2

11.9%

T

970 C

CO

4572

Pst

-8

NOx

888

O2

3.34 % EP outlet

Tertiary air temp

T

Calciner to C2 gas duct

750 C

T

150 C

Pst

- 9.9

Cooler waste gas To coal mill

T

270 C

Pst

-3.7

Clinker temperature Crusher inlet

EP inlet T

161 C

CO

2375

Pst

3.2

NOx

454

O2

11.7 %

T

543 C

Pst O2

7%

Page 34 of 37

Crusher outlet CO

5000

T

NOx

509

Pst O2

370C

8%

T CO

3650

Hot gas to coal mill

NOx

391

T

491 C

Pst

-10

210 C

Chart 14 Measurement flat without safety railing

Chart 15 No safety protection screen on bleed air damper of cooler exhaust gas duct

Page 35 of 37

Chart 16 No safety protection screen on bleed damper of hot gas to coal mill gas duct

Chart 17 The cables on floor

Page 36 of 37

Action table from 2006 audit

Table of actions

No.

Action

Priority

1

Proper step or ladder for the measurement points should be installed; some handrails must be installed also.

Safety

2

Alarm marks should be fixed on the Preheater concrete beams overhead the accesses

Safety

3

Gangways on the scaffolding optionally must be carried away to keep from falling down.

Safety

The Kiln Feed Fluctuation has to be reduced to +/-1% from 40%. 4

Improve vacuum filter performance to reduce the feed material quantity and quality deviation.

1

5

Install thermocouples at Precalciner bottom, middle, upper and kiln inlet. Cross-check Preheater manometers and thermocouples regularly to achieve more uniform combustion and decarbonatation

1

6

Increase O2 in preca by reducing inleakage and install proper instrumentation

1

8

Improve drying crusher air sealing and weld or change duct to reduce false air

1

9

Control KFUI