• Like
Coal
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

Published

 

Published in Technology , Business
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads

Views

Total Views
643
On SlideShare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
86
Comments
0
Likes
0

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. Adhunik Power & Natural Resources Ltd. Impact of Coal Quality on PlantImpact of Coal Quality on Plant Life & PerformanceLife & Performance
  • 2. After the liberalization of Import, most of the Power Stations are attracted towards using Imported Coal due to: 1)Higher Calorific Value 2)Low Ash Content 3)Low Price per Unit of Energy. Boilers in India are designed for high ash content Coal, which has lead to: 1)Large scale erosion of components leading to high Maintenance Cost 2)Low Availability 3)Lower PLF in due course of time. Use of Imported coal has lead to Severe Operation Problems & Outages because of basic Design features particularly in PF & FBC Boilers. Coal has basically two components: 1)Marcels (Organic Matter) - Responsible for Heat Value 2)Mineral Matter (Inorganic Matter) - Responsible for Ash Components Distribution of qualities of these two components effect the Coal Combustion & thereby Boiler designs in Principle.
  • 3. COAL COMBUSTIONCOAL COMBUSTION COAL ParticleCOAL Particle HeatingHeating Formation of CharFormation of Char Burning of VolatilesBurning of Volatiles Release of VolatilesRelease of Volatiles Burning of CharBurning of Char Ash FormationAsh Formation Each process has its own time depending on Characteristic, distribution & size of Marcels & Mineral Matter. Different Analysis is used to Assess the Coal Combustion Characteristic. Previously well known analysis were: 1.Proximate Analysis. (Rank of Coal) 2.Ultimate Analysis (Elemental Chemical Composition)
  • 4. NEW METHODS FOR ANALYSIS OF MARCELS 1. Differential thermogravimetic Analysis (DTG) Burning profile Observation  Profile extends to higher temp. Range High Wt. loss at low Temp.  High Peak at low Temp High Peak at higher temp  High Burn out temperature Effects Slow Burning Coals Good Burning Good flame stability Increase furnace temp. Require  Large furnace  Leading to high S/H temp.  Consequently tube failure No problem Problem in water wall higher unburned carbon
  • 5. 2. Modified Bomb calorimeter (ISO Periobol Bomb Calorimeter) 3. Petro graphic Analysis Observation Heat Release rate Reactivity Effects  Faster heat Release initially & slow towards end.  Slow rate initially faster afterwards Virtinite >62.7% Virtinite ≤62.7% Exinites Intertinite Require  Requires high absorption surface in furnace zone.  High furnace vol. Rise in temp of S/H, Eco, etc & low Boiler Efficiency. Difficult to burn Good Burning char highly reactive.  Less reactive  High unburned carbon NEW METHODS FOR ANALYSIS OF MARCELS contd…..
  • 6. MINERAL MATTER Three aspects of mineral matter influences the ash formation 1.Nature of mineral matter (Included/Excluded). 2.Particle size distribution. 3. Form of mineral matter Ash contains SiO2, Al203, Fe2O3, CaO, MgO, Na2O K2O, TiO2 & SO3 Ash fusion temperature depends upon the quality & quantity of these oxides.
  • 7. ASH CHARACTERISTICS Ash Analysis High Iron Content Clinker formation & furnace temp. limitation Iron > 19% 10-12% 4-8% Furnace Temp.< 1200⁰C < 1300⁰C Max. 1400-1450⁰C Slagging Index < 0.6 0.6-2.0 2-2.6 > 2.6 Boiler Slagging (Deposits of Ash on waterwall) Low Medium High Severe Fouling Potential <0.2 0.2-0.5 0.5-1.0 >1.0 Fouling Potential (Deposits of Ash in S/H) Low Medium High Severe Ash Fusion Temp. Higher Ash Fusion Temp. >1100⁰C <1100⁰C No clinkering tendency. High clinkering tendency. Erosion Index <1.0 >1.0 Erosion of Boiler & Mill Internals Low High
  • 8. ENVIRONMENTAL RESTRICTION Most of the Imported coals have high sulpher content compared to Indian coal. The design of ESP & stacks are based upon the low sulpher content of Indian coal. In Europe & other place desulphurization units are mandatory parts of the boiler system which are absent in India. Blend rations are to be decided upon keeping in mind the Pollution norms in India, otherwise Desulphurization Equipments or increase in the height of stack is must.
  • 9. COAL BLENDING Keeping in mind the design features & others, we can operate Indian boilers with blended coal i.e. a mixture of Imported coal & Indian coal, limited to the blend ratio, which is most nearest to their design. Inspite of best of blending each particle of coal burns as per their own characteristic. The blend Ratio can be decided by 1.Full Scale trails on Boiler- Costly and time consuming. 2.Analyzing Burning Profile of Blended coal at laboratory level. A study of burning Profile of various mix of Indian coal & South African coal is represented graphically for typical PF boiler. From it is quite clear that a 30% blend Ratio of Imported to Indian coal has nearly similar burning profile with similar peaking temperature which is a vital parameter of furnace design. Similar study can be made for available imported coals & blend ratios can be fixed for all the boilers in our group scientifically without inviting costly full scale trials.
  • 10. BLENDING METHODS Proper blending of coal is always a difficult task. Lower the particle size better is the blending but limited to feeding of size requirement in boiler. Difficulties: 1.Stoker fired boiler-Improper mix due large size of feed requirement 2.Large area requirement if blending is done in yard. 3.Difficulty in measurement of accurate blends ratio. Following are the basic guidelines for better blending: 1.Giving feed from two different sources to common pint on conveyor. 2.Proper mixing by tilting at number of transfer pints before crushing. 3.Common crushing, so that further mixing takes place during crushing.
  • 11. EXECUTIVE SUMMARY INDONESIAN COAL PROXIMATE ANALYSIS ASH % MOISTURE % VOLATILE MATTER % FIXED CARBON % GCV Kcal/kg 16.41 6.80 36.25 40.54 5696 1. Trail on FBC Boiler i.e. EC4 for 100% blend, gains were Rs. 40,000 per day. 2. Blend ratio to be limited to 30% due to SO2 norms. 3. Gain at 30% Blend Ratio approx. 15000/day in EC4. 4. Gain for EC1 & EC2 to be calculated after trails. 5. Gain will be available for 8-9 months only, i.e. excluding Monsoon Period.
  • 12. PROXIMATE ANALYSIS ASH % MOISTURE % VOLATILE MATTER % FIXED CARBON % GCV Kcal/kg 17.36 3.33 22.23 57.08 5998 SOUTH AFRICAN COAL 1. Loss in Boiler Efficiency due to high unburned carbon. 2. Net Gain Rs. 60,000 per day for 400 TDP steam. 3. Blend ratio to be limited to 25-30% due to SO2 norms & problems of clinkering & high flue gas temp in PF boilers of EC1. 4. Expected gain on continuous basis shall be approximately 50000-55000/day. 5. Gain will be available for 8-9 months only, i.e. excluding Monsoon Period.
  • 13. COST IMPACT OF MOISTURE ON C.V.Cost including Freight (Cif) value at 6500 Kcal = Rs. 1160/ton Landed Cost = Rs. 2145/ton An increase in 1% Moisture has a reduction of Rs. 11.60/ton as per weight basis. Whereas for a Reduction in Gross Calorific value because of high moisture by 1%, the corresponding loss is about 64 kcal. Conversion factor at 2.5% moisture = (100-{2.5+1})/(100-2.5) = 6433 kcal Difference in C.V. = 6500-6433 = 64 kcal Cost/kcal = 2145/6500 = Rs. 0.33/kcal = Rs. 33/100 Kcal Equivalent Cost for 67 Kcal = 33/100 x 67 = Rs. 22 Total Loss = Rs. 22- Rs. 11.60 approx. Rs. 11
  • 14. Unit Stroker Fired Boilers Fluidized Bed Boilers Pulveriz ed Fuel Boilers Under Grate Spreader Chain/ Travelling Gate Bed Super Heater Convective Super Heater Stationary Moving Proximate Analysis Moisture % 0-10 0-10 0-25 0.20 5-10 8-15 5-10 Volatile Matter % 30-40 30-40 18-30 30-40 20-40 20-40 15-25 Fixed Carbon % 40-50 40-50 50-65 40-50 30-40 30-40 30-50 ASH % 5-10 5-10 5-15 10-20 >25 >25 >20 FC/VM % 1-1.25 1-1.25 1-1.25 1-1.25 1.4-1.6 <1.5 <2.0 C.V. Kcal /kg 6500- 7500 6500- 7500 5000- 6000 4500- 5500 3000- 4000 5000- 6000 Rank Semi Anthracite Sub Bituminous Free Swelling Index 5 Max 7 Max NA 5Max NA NA NA HGI NA NA NA NA NA NA 50-70 SPECIFICATION OF COAL
  • 15. Unit Stroker Fired Boilers Fluidized Bed Boilers Pulveriz ed Fuel Boilers Under Grate Spreader Chain/ Travelling Gate Bed Super Heater Convectiv e Super Heater Stationary Moving Statutory Req. Sulphur ^ <0.5 <0.5 <0.5 <0.5 <0.7 <0.7 <0.5 Moisture % 0-10 0-10 0-25 0.20 5-10 8-15 5-10 Ash Characteristics Erosion Index (EI) NA NA NA NA <1.0 <1.0 <1.0 Ash softening Temp ⁰C 13501400 1350- 1400 1050- 1100 1125-1175 >1200 >1150 >1100 Slagging Index NA NA NA NA <0.6 <0.6 0.6-2.0 Fouling Indes NA NA NA NA <0.2 <0.2 0.2-1.0 Origin
  • 16. GRASIM NAGDA Analysis & Summary of 100% Imported Coal Use in EC4 (INDONESIAN COAL) SNo Particulars Unit EC4 Remarks 1. Furnace Temperature ⁰C 782 Improved Norm 2. Bed Temperature ⁰C 922 Within Norms 3. Stack Temperature ⁰C 119 No Dev. From SECL Coal 4. Main Steam Flow TPH 89 5. Main Steam- SECL TPH 81 6. Main Steam Flow-Parta TPH 85 7. Coal Consumption a. Imported b. 100% SECL c. Parta TPD TPD TPD 294 313 331 8. Blend Ratio % 100 9. Calorific Value a. Imported b. 100% SECL c. Parta d. Gain/loss from SECL Kcal/kg Kcal/kg Kcal/kg Kcal/kg 5700 4807 4833 893
  • 17. Sr. No. Particulars Unit EC4 Remarks 10 Boiler Efficiency a.Direct Method b.Loss Method c.Average d.SECL e.Gain/loss from SECL % % % % % 81.87 84.58 83.20 83.78 -0.58 11 Cost of Coal a.Imported b.SECL c.Parta d.Gain/Loss from SECL Rs./T Rs./T Rs./T Rs./T 2115 1905 1988 -210 Rs 1959 at 4944 kcal At 4833 kcal, April 99 Parta 12 Coal Cost/100 Kcal a.Imported b.SECL c.Parta d.Gain/Loss from SECL Rs T/1000 Kcal Rs T/1000 Kcal Rs T/1000 Kcal Rs T/1000 Kcal 371 396 411 25 13 Cost of steam a.Imported b.SECL c.Parta d.Gain/Loss from SECL Rs./T Rs./T Rs./T Rs./T 286 305 324 19 14 Gain/loss From SECL Rs/Day 40570 At 89 TPH Steam 15 Gain /loss from SECL at Parta Steam Rs/Day 38619 At 85 TPH steam
  • 18. Grasim Nagda (SOUTH AFRICAN COAL) Analysis & Summary of Blending Imported Coal with SECL Coal From 03/07/99-05/07/99 S.N. Particulars Unit EC1 EC2 EC4 TOTAL/Wt d Remarks 1 Furnace Temp. ⁰ C 857 643 722 748 Increasing Trend in EC1 2 Bed Temp ⁰ C 891 922 910 Within norms 3 Stack Temp ⁰ C 171 155 119 146 No dev. From SECL Coal 4 Main Steam Flow TPH 141 104 166 411 5 Main Steam- SECL TPH 141 101 158 400 6 Main Steam Flow-Parta TPH 135 105 158 398 7 Coal Consumption a.Imported b.SECL c.Total d.100% SECL e.Parta TDP TDP TDP TDP TDP 137 342 479 487 491 141 277 418 419 410 166 367 533 533 596 444 986 1430 1439 1497 8 Blend Ratio % 29 34 31 31 9 Calorific Value a. Imported b. Blended c. SECL Blended d. 100% SECL e. Parta f. Gain/loss from SECL Kcal/kg Kcal/kg Kcal/kg Kcal/kg Kcal/kg Kcal/kg 5998 5229 4921 4779 4833 308 5998 5273 4904 4677 4833 369 5998 5194 4830 5025 4833 364 5998 5229 4882 4840 4833 346 As fired basis-10% moisture Derived Value
  • 19. S.N. Particulars Unit EC1 EC2 EC4 TOTAL/Wtd Remarks 10 Boiler efficiency a.Direct Method b.Loss Method c.Average d.SECL e.Gain/loss from SECL % % % % % 82.86 86.17 84.48 88.46 -3.98 71.62 80.49 75.80 78.53 -2.73 88.17 81.62 84.77 85.23 -0.46 81.55 82.81 82.05 84.35 -2.30 Bunker level correction Not accounted for in EC2 & EC4 11 Cost of Coal a.Imported b.Blended c.SECL d.Parta e.Gain/Loss from SECL Rs/T Rs/T Rs/T Rs/T Rs/T 2145 2002 1894 1988 -108 2145 2012 1853 1988 -159 2145 1986 1991 1988 5 2145 1999 1918 1988 -81 At 5998 kcal & 10% moisture Derived value Rs 1959 at 4944 kcal At 4833 kcal, April 99 Parta 12 Coal Cost/1000 kcal a.Imported b.Blended c.SECL d.Parta e.Gain/Loss from SECL Rs T/1000 Kcal 358 383 396 411 13 358 382 396 411 15 358 382 396 411 14 358 382 396 411 14 13 Cost of Steam a.Imported b.SECL c.Parta d.Gain/Loss from SECL Rs/T Rs/T Rs/T Rs/T 267 275 302 8 318 322 327 4 277 285 312 8 286 292 313 7 14 Gain/loss from SECL Rs/Day 27072 9984 31872 68928 At 411 TPH steam 15 Gain/loss from SECL at Parta Steam Rs/Day 25920 10109 30336 66365 At 398 TPH steam
  • 20. OUR RECOMMENDATIONS 1. Use of Indonesian Coal at 25-30% Blend Ratio. 2. If possible use of South African coal to be avoided because of clinking nature of coal.