Loesche Round Table MCL

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(1)Operating Experience of the Upgradation of Raw and Coal mill at MCL Alathiyur M. Srinivasan S. Shanmugam. : :. Sr. VP (Mfg.) VP (Mfg.).

(2) Contents  Introduction  Raw Mill LM 38.3 Upgradation with LSKS 57 Classifier and Vortex Rectifier.  Coal Mill LM 20.2D Upgradation with LSKS 36ZD Classifier for Pet coke grinding. Loesche India Round Table 2012. 2. © by LOESCHE GmbH.  Conclusion.

(3) Introduction  Madras Cement Ltd. (MCL) is a flagship company of RAMCO Group.. ISO 14001:2004. Loesche India Round Table 2012. ISO 9001:2008. IS 18001:2007. 3. © by LOESCHE GmbH.  MCL is having five Cement manufacturing units, three cement grinding units and two packing units with the total annual capacity of 13 Million tones..

(4) MCL Alathiyur plant with two clinkerisation units, is located at Alathiyur in Tamil Nadu, India.. Loesche India Round Table 2012. 4. © by LOESCHE GmbH. Introduction.

(5) Introduction. Loesche India Round Table 2012. 5. © by LOESCHE GmbH. MCL Alathiyur Cement Plant, Tamil Nadu.

(6) Introduction.  The cement plant at Alathiyur was setup in two phases.  Line-I was installed with a capacity of 2350 tones/day in 1997 and presently operational at 3500 tones/day.  Line-II was installed with a capacity of 3000 tones/day in 2001 and presently operational at 3500 tones/day.  Line-II was repeat of Line-I with upgraded capacity..  The products manufactured are Ordinary Portland Cement as per BIS & Sri Lanka Standards (SLS), Portland Pozzolana Cement and Sulfate Resistant Portland Cement (SRPC).. Loesche India Round Table 2012. 6. © by LOESCHE GmbH.  Loesche VRM LM 56.2+2C was considered for clinker grinding in Line-II in place of OK mill 33.4 of Line-I.

(7) Introduction. Line 1. Line 2. Commissioned (year). 1997. 2001. Kiln. FLS – 3500 t/d. FLS - 3500 t/d. Raw Mill. Loesche LM38.3. Loesche LM38.3. Coal Mill. Loesche LM20.2D. Loesche LM20.2D. Clinker Mill. O.K 33.4. Loesche LM 56.2+2 C.  Two coal based captive thermal power plants each 18MW ensure uninterrupted power supply. Loesche India Round Table 2012. 7. © by LOESCHE GmbH. Alathiyur Plant Details.

(8) 8. © by LOESCHE GmbH. Loesche India Round Table 2012.

(9) . Introduction: Raw Mill LM 38.3. . Technical Details of Raw Mill. . Operating data before modifications. . Constraints in plant operation. . Driving force for the upgradation. . Modifications carried out. . Classifier Details. . Vortex Rectifier. . Comparative Opertaing Data. . Benifits achieved after upgradation. Loesche India Round Table 2012. 9. © by LOESCHE GmbH. Contents: Raw Mill LM38.3.

(10) Introduction : Raw Mill LM 38.3. Raw Mill-1 was commissioned with rated capacity of 180t/h @17%R90 µm to cater the kiln of 2350t/d in 1997. Raw Mill-II was commissioned with rated capacity of 215 t/h @ 17%R90 µm to cater the kiln of 3000t/d in 2001. By the time of ordering Line-II, MCL decided to upgrade Line-I to have same capacities. Raw Mill-I was successfully upgraded by replacing classifier from LJKS65 to LSKS52 and bigger tires in 2000/2001.. Loesche India Round Table 2012. 10. © by LOESCHE GmbH. Both raw mills were in smooth & stable operation at output of 215-220 t/h @17% R90µm.

(11) Technical Details of Raw Mill Type of mill. LM38.3. Rated Capacity (t/h). 215 @ 17% R 90μm. Feed Moisture (%). Normal: 5. Table diameter (mm). 3800. Grinding rollers. 3 Nos.. Main Gear Box. Flender KMP 450. Main Gear box rating (kW). 1320. Classifier Size. LSKS52. 11. © by LOESCHE GmbH. Loesche India Round Table 2012. Maximum:10.

(12) Constraints in plant operation. The Raw mill was designed for a feed moisture of 5% normal & 10% maximum. Over a period of time, the normal feed moisture increased to more than 10% causing the reduced raw mill output to 205-210 t/h from 215-220 t/h. During monsoon, Mill output was further reducing to 190 t/h. Hot Gas Generator (HGG) had to be operated to get the output of 210 t/h to meet the clinker production. Since more heat was required for drying, the gas volume was to be increased in mill and thereby causing higher product residue.. Loesche India Round Table 2012. 12. © by LOESCHE GmbH. Raw Mill motor was overloaded frequently with periodic power kicks..

(13) Constraints in plant operation.  Kiln feed had to be reduced as the Raw mill was unable to support the raw meal requirement.  At high residue of raw meal on 212 µm, problems related to clinker burning resulted in high free lime of >2.5%.  HGG had to be turned on, consuming about 2 t/h of fine coal.  Raw mill with HGG met the raw meal requirement but residue was still high.. Loesche India Round Table 2012. 13. © by LOESCHE GmbH.  The raw mill fan was a bottleneck to handle higher gas flow..

(14) Description. Raw Mill 1. Raw Mill 2. Feed Moisture (%). >=10%. >=10%. Mill Output dry (t/h). 207. 210. Product Residue % 212 µm. 2.5-3.0. 2.5-3.0. Product Residue % 90 µm. 19-20. 19-20. Mill Motor Power (kW). 1150. 1170. Fan Power (kW). 1310. 1530. Specific Power: Mill (kWh/t). 5.56. 5.57. Specific Power: Fan (kWh/t). 6.32. 7.29. Total Specific Power (kWh/t). 11.89. 12.86. Loesche India Round Table 2012. 14. © by LOESCHE GmbH. Operating data of Raw Mills before modifications.

(15) Driving Force for the Upgradation.  MCL decided to further enhance the kiln capacity to 3500 t/d  Accordingly the revised capacity requirement from raw mill was>= 230 t/h to support the upgraded kiln.. Loesche India Round Table 2012. 15. © by LOESCHE GmbH.  Product residue @212 µm was required to be less than 2%.

(16) Modifications Carried out. . Replacing the existing classifier from LSKS 52 by a larger size LSKS 57 with inbuilt Vortex Rectifier. This was the first Vortex rectifier in India.. . Modified louver and armor ring to maintain uniform gas flow/velocity profile inside the mill.. . Increase the capacity of the raw mill fan by replacement/ retrofitting. . Increase the size of the following ducts due to higher gas flow:. Loesche India Round Table 2012. 16. © by LOESCHE GmbH. Mill inlet duct Mill Outlet duct Duct from Cyclone to mill fan inlet.

(17) Classifier Details. Description. LSKS52. LSKS57. Rotor diameter (mm). 3080. 3400. Rotor Height (mm). 2000. 2200. Area of rotor (m2). 19.35. 23.50. Loesche India Round Table 2012. 17. © by LOESCHE GmbH. Comparison between LSKS52 and LSKS57.

(18) Classifier Details. Vortex Rectifier. LSKS Loesche India Round Table 2012. LSKS With Vortex Rectifier 18. © by LOESCHE GmbH. Rotor.

(19) Vortex Rectifier Vortex Rectifier reduces the turbulences at the mill outlet  Vortex kinetic energy recuperation  Homogenous velocity distribution at mill outlet. Loesche India Round Table 2012. 19. © by LOESCHE GmbH.  Uniform/ laminar flow pattern at mill outlet.

(20) Vortex Rectifier. Hard twisted gas flow created by high speed rotation of classifier rotor. Loesche India Round Table 2012. With vortex Rectifier Uniform and Laminar Flow. 20. © by LOESCHE GmbH. Without Vortex Rectifier.

(21) Vortex Rectifier Flow Characteristics Results of CFD. Classifier with vortex rectifier. Classifier without vortex rectifier Laminar Flow. Loesche India Round Table 2012. 21. © by LOESCHE GmbH. Turbulent Flow.

(22) Vortex Rectifier. Loesche India Round Table 2012. 22. © by LOESCHE GmbH. Actual Photographs during installation at site..

(23) Description. Before Modification. After Modification. LSKS 52. LSKS 57. >=10. >=10. 207. 231. Product Residue 212 µm (%). 2.5-3.0. 1.5-2.0. Product Residue 90 µm (%). 19-20. 16-17. Specific Power: Mill (kWh/t). 5.56. 4.55. Specific Power : Fan (kWh/t). 6.33. 6.28. Total Specific Power (kWh/t). 11.89. 10.83. Classifier Size Feed Moisture (%) Mill Output (t/h) dry. Loesche India Round Table 2012. 23. © by LOESCHE GmbH. Comparative operating data of Raw Mill 1.

(24) Description. Before Modification. After Modification. LSKS 52. LSKS 57. >=10. >=10. 210. 233. Product Residue 212 µm (%). 2.5-3.0. 1.5-2.0. Product Residue 90 µm (%). 19-20. 15-16. Specific Power : Mill (kWh/t). 5.57. 4.42. Specific Power : Fan (kWh/t). 7.29. 6.52. Total Specific Power (kWh/t). 12.86. 10.94. Classifier Size Feed Moisture (%) Mill Output (t/h) dry. Loesche India Round Table 2012. 24. © by LOESCHE GmbH. Comparative operating data of Raw Mill 2.

(25) Comparative operating data. Improvement. Raw Mill 1. Raw Mill 2. 11.59. 10.95. Product Residue % on 90 µm. 3 (Absolute). 4 (Absolute). Product Residue % on 212µm. 1 (Absolute). 1 (Absolute). Specific Power : Mill Motor (kWh/t). 1.01. 1.15. Specific Power : Fan (kWh/t). 0.05. 0.77. Total Specific Power (kWh/t). 1.06. 1.92. Output (%). Loesche India Round Table 2012. 25. © by LOESCHE GmbH. Performance Improvement.

(26) Benefits achieved from upgradation.  At feed moisture >=10% average output increased to >230 t/h at improved residue.  Product Residue on 212 µm, which is crucial for burning came down to 1.52%.  Product Residue on 90 µm came down to 15-16%.  The mill can be operated at 240t/h-245t/h with increased Hot Gas from HGG.  Saving of about 1-2 kWh/t in specific power drawn by mill and fan.. RM-1 :. 10.82 kWh/t. RM-2 :. 10.94 kWh/t. Loesche India Round Table 2012. 26. © by LOESCHE GmbH.  Achieved the lowest specific power consumption (mill + fan).

(27) . With improved particle size distribution of mill product, free lime in clinker reduced to <2%. . Quality of clinker improved : C3S >=55%. . Kiln is being operated to its full capacity due to increased raw meal of better quality. . Stable Kiln Operation established. Loesche India Round Table 2012. 27. © by LOESCHE GmbH. Benefits achieved from Upgradation.


(29) . Introduction: Coal Mill LM 20.2D. . Technical Details of coal mill. . Difficulties in Pet coke grinding. . Solutions for Pet coke Grinding. . Modifications carried out. . Classifiers. . Comparative Operating Data in Pet coke Grinding. . Comparative Operating Data in Coal Grinding. . Benefits achieved from Upgradation. Loesche India Round Table 2012. 29. © by LOESCHE GmbH. Contents : Coal Mill LM 20.2D.

(30) Introduction : Coal Mill LM 20.2D. MCL Alathiyur has two Coal mills of LM 20.2D size. The coal mills were designed for lignite grinding with central feed.. Loesche India Round Table 2012. 30. © by LOESCHE GmbH. The coal mills were operating smooth & stable, meeting all performance guarantees..

(31) Mill Size. LM 20.2 D. Fuel Type. Lignite / Coal. Feed Moisture (%). 15. Product Rate (t/h). 23 ( wet basis ). Product residue % @90μm. 15. Table diameter (mm). 2000. Grinding rollers. 2 Nos.. Main Gear Box. Flender KMS 595. Main Gear box rating (kW). 330. Classifier Size. LKS 40ZD. Loesche India Round Table 2012. 31. © by LOESCHE GmbH. Technical details of Coal Mill.

(32) Difficulties in Pet coke grinding  MCL started using imported Pet coke & coal due to techno-economic reasons.  In Pet coke grinding, the mill operation was very unstable due to non-uniform bed formation  Due to spheroid and uniform shape of Pet coke, the nipping under rollers is extremely difficult.  Due to the low volatile matter in Pet coke, it has to be ground to a fineness of <2% Residue on 90µm for complete combustion.. Loesche India Round Table 2012. 32. © by LOESCHE GmbH.  The existing LKS Classifier was not able to provide efficient separation for the very fine grinding of Pet coke. The fines along with grits returning on the table leads to over grinding and unstable bed formation..

(33) Solutions for Pet coke Grinding. The stability of mill could be achieved/improved by: . An efficient and state of art classifier, designed suitably for very fine grinding, minimizes the fines in return grits.. . Due to reduced fines in return grits, the over grinding is avoided and stable/uniform bed formation is ensured.. . Increasing dam ring height. . Water sprinkling on table. . Reducing table speed (varying mill motor speed). Loesche India Round Table 2012. 33. © by LOESCHE GmbH. Additionally the bed stability can be influenced by:.

(34) Modifications Carried out.  Replacing the existing classifier from LKS 40ZD by LSKS 36ZD  Modified louver and armor ring to maintain uniform gas flow/velocity profile inside the mill.. Loesche India Round Table 2012. 34. © by LOESCHE GmbH.  Modified dam ring suitable for Pet coke grinding.

(35) LKS Classifier Loesche India Round Table 2012. New LSKS Classifier 35. © by LOESCHE GmbH. Classifiers: LKS...ZD and LSKS...ZD Type.

(36) Comparative Operating Data in Pet coke Grinding. Classifier Size. Before Modification. After Modification. LKS 40 ZD. LSKS 36 ZD. Output (dry basis) (t/h). 13. 17. Product Residue @ 90 µm (%). 4. 1.5 -2. Mill Motor Power (kW). 250. 190. Fan Power in GRR Mode (kW). 420. 450. Specific Power: Mill (kWh/t). 19.23. 11.18. Specific power: Fan (kWh/t). 32.30. 26.47. Total Specific Power (kWh/t). 51.53. 37.65. Loesche India Round Table 2012. 36. © by LOESCHE GmbH. Description.

(37) Comparative Operating Data in Coal Grinding. Classifier Size. Before Modification. After Modification. LKS 40 ZD. LSKS 36 ZD. Output (dry basis) (t/h). 23. 28. Product Residue @ 90 µm (%). 18. <16. Mill Motor Power (kW). 280. 230. Fan Power in GRR Mode (kW). 440. 475. Specific Power: Mill (kWh/t). 12.17. 8.21. Specific Power: Fan (kWh/t). 19.13. 16.96. Total Specific Power (kWh/t). 31.30. 25.17. Loesche India Round Table 2012. 37. © by LOESCHE GmbH. Description.

(38) Improvement. Coal. Pet coke. Mill Output dry basis (%). 21.73. 30.76. Product Residue % 90µm. 2 (Absolute). 2 (Absolute). 6.13. 13.88. Specific Power (kWh/t) Mill + Fan. Loesche India Round Table 2012. 38. © by LOESCHE GmbH. Benefits achieved from Upgradation.

(39) Benefits achieved from upgradation.  Pet Coke usage increased up to 85%  Improved mill stability ; especially in Pet Coke grinding  Mill Vibration reduced to <2mm/sec  Improved burning efficiency in kiln due to homogenous quality of pulverized fuel  Abnormal coatings in Kiln eliminated  Kiln is being operated to its full upgraded capacity. Loesche India Round Table 2012. 39. © by LOESCHE GmbH.  Reduced running hours of coal mill and it’s increased availability for maintenance etc..


(41) Conclusion  The performance of upgraded raw mill and coal mill met the expectation of MCL to cater the enhanced kiln capacity at improved clinker quality.  With significant saving in specific power of grinding sections, MCL achieved specific power consumption of 63-64 kWh/t in PPC for complete plant, which is the benchmark in the industry.  The series of national awards for the highest energy efficient plant bears a testimony of innovative commitment by MCL.  MCL would like to put on record the appreciation for continuous support given by OEM such as Loesche to meet the target.. Loesche India Round Table 2012. 41. © by LOESCHE GmbH.  MCL firmly believes in continual improvement and is working together with Loesche to further reduce specific power ; especially in clinker grinding with similar Upgradation philosophy..

(42) THANK YOU.

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