CLASSIFICATION OF COAL
By Satyajit Rout
TERMS USED
 V(VM) : volatile matter content
 C : Carbon content
 A : ash content
 M : moisture content
 O: oxygen
 N...
CLASSIFICATION AND ITS OBJECTIVE
 Classification means classifying or categorising
objects as per their characteristics o...
CLASSIFICATION OF COAL
 Coal is a naturally available heterogeneous organic
mass. So very difficult to classify.
 Hence ...
CLASSIFICATION BY VISUAL CHARACTERS
Category Attributes Flame
Brown coal/lignite Brown colour, woody
structure
-----------...
CLASSIFICATION BASED ON THEIR SOURCE OF
GENESIS: HUMIC AND SAPROPELIC COAL
Humic coal:
 Those developed from terrestrial ...
CLASSIFICATION BY ULTIMATE ANALYSIS:
1. REGNAULT-GRÜNER-BROSQUET SYSTEM
 First attempt in 1837
 Based on the C, H, O con...
Classification table of Regnault-Grüner-Brosquet system
2. SYLER’S CLASSIFICATION
 The complete system was published in 1899
 %age of C, N, O and H is considered in dry ash
sul...
SEYLER’S CLASSIFICATION (CTD…)
 Lignitous
1. Meta (80-84% C)
2. Ortho (75-80% C)
 Hydrogen planes
1. Per- hydrous(>5.8% ...
SEYLER’S CHART
3. GROUT AND RALSTON CLASSIFICATION
 In 1907 Grout plotted C, H, O contents of American
Coal on a tri-axial diagram.
 Th...
CLASSIFICATION BASED ON PROXIMATE
ANALYSIS
 Moisture, volatile matter, ash, fixed carbon content
play the role of criteri...
CLASSIFICATION BASED ON PROXIMATE
ANALYSIS
2. Frazer’s classification:
 In 1877, he used fuel ratio to classify coal as
g...
CLASSIFICATION BASED ON PROXIMATE
ANALYSIS
3. Campbell classification:
 also based on fuel ratio but all coals below 5 FR...
CLASSIFICATION INVOLVING BOTH PROXIMATE
ANALYSIS AND CALORIFIC VALUE:
1. Parr’s classification:
 He considered Volatile C...
PARR’S CLASSIFICATION
[V as determined-(0.8A+0.4S)]X 10
 unit VM=------------------------------------------------
100-(1....
A.S.T.M. CLASSIFICATION
 It classifies coal to 4 broad classes based on fixed
carbon and calorific value (BTU) on dry min...
Class or
Rank
Group
Fixed Carbon (wt % dry
mmf)
Volatile Matter (wt % dry mmf)
Gross
Heating Value (MJ/kg moist
mmf)
Equal...
CLASSIFICATION BY NATIONAL COAL BOARD
 Specifically designed for commercial use
 Rank based
 Uses 3 digit code to ident...
Class
Volatile matter1)
(weight %)
General description
101 < 6.1
Anthracites
102 3.1 - 9.0
201 9.1 - 13.5 Dry steam coals
...
INTERNATIONAL CLASSIFICATION OF HARD
COAL
 Mainly for anthracites and bituminous coal but
covers fairly all kinds
 Uses ...
CLASSIFICATION OF INDIAN COAL
Scientific Coding of Indian Coal
 3 basic parameters and 1 supplementary
parameter
 1st di...
GRADING OF INDIAN COAL
 For grading of Non-Coking coal useful heat value is used,
which is calculated by
HU= 8900- 138(as...
GRADING OF NON- COKING COAL
Grade Useful heat value(kcal/kg)
A >6200
B 5601-6200
C 4941-5600
D 4201-4940
E 3361-4200
F 240...
GRADING OF COKING COAL
Grades Ash content
Steel I <15%
Steel II 15-18%
Washery grade I 18-21%
Washery grade II 21-24%
Wash...
CLASSIFICATION FOR EXPORT PURPOSE
Grade Low volatile High volatile
Selected <13% A; >7000 cal <11% A; <6% M; >6800 cal
Fir...
REFERENCE
 Sarkar S. (1988), “Fuels and Combustion”, Orient
Longman Publication, 2nd edition, pp-71-85
 Rose H.J.(1945),...
THANK YOU
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Coal classification

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Coal classification

  1. 1. CLASSIFICATION OF COAL By Satyajit Rout
  2. 2. TERMS USED  V(VM) : volatile matter content  C : Carbon content  A : ash content  M : moisture content  O: oxygen  N: nitrogen  H: hydrogen, S: sulfur  daf: dry ash free basis  dmmf: dry mineral matter free basis  BTU: British thermal unit
  3. 3. CLASSIFICATION AND ITS OBJECTIVE  Classification means classifying or categorising objects as per their characteristics or property.  Objective is to place like things together and separate things that differs.
  4. 4. CLASSIFICATION OF COAL  Coal is a naturally available heterogeneous organic mass. So very difficult to classify.  Hence for last 150 years many attempts have been made.  Since then many system of classifications have classified coals according to different classification basis.  Followings are examples of such classification system.
  5. 5. CLASSIFICATION BY VISUAL CHARACTERS Category Attributes Flame Brown coal/lignite Brown colour, woody structure ---------------- Bituminous coal Black and banded Smoky yellow flame Anthracite Black and lustrous Burns without flame
  6. 6. CLASSIFICATION BASED ON THEIR SOURCE OF GENESIS: HUMIC AND SAPROPELIC COAL Humic coal:  Those developed from terrestrial plant debris that was exposed to atmosphere and passed through peat stage  Higher plant kingdom is source Sapropelic coal:  Developed from plankton, algae, terrestrial plant but in anaerobic or Lacustrine condition.  E.g. bog head coal, cannel coals
  7. 7. CLASSIFICATION BY ULTIMATE ANALYSIS: 1. REGNAULT-GRÜNER-BROSQUET SYSTEM  First attempt in 1837  Based on the C, H, O content  Only includes coal with more than 75% carbon on d.a.f basis.  Initially Regnault gave a system considering only O+N but later modified
  8. 8. Classification table of Regnault-Grüner-Brosquet system
  9. 9. 2. SYLER’S CLASSIFICATION  The complete system was published in 1899  %age of C, N, O and H is considered in dry ash sulfur free basis  His classification divided coal into 7 carbon planes and 2 hydrogen planes.  The 7 carbon planes are  Anthracite (>93.3% C)  Carbonaceous (91.2-93.3% C )  Bituminous 1. Meta(91.2-89% C) 2. Ortho(87-89% C) 3. Para (84-87% C)
  10. 10. SEYLER’S CLASSIFICATION (CTD…)  Lignitous 1. Meta (80-84% C) 2. Ortho (75-80% C)  Hydrogen planes 1. Per- hydrous(>5.8% of H) 2. Sub hydrous(< 4% of H) Disadvantages  Complex naming  Inadequate classification for low rank coals  Applicable only to British Carboniferous Coal
  11. 11. SEYLER’S CHART
  12. 12. 3. GROUT AND RALSTON CLASSIFICATION  In 1907 Grout plotted C, H, O contents of American Coal on a tri-axial diagram.  The plot separated cannel coal(high H) from ordinary coal  Classification was based on dry-ash free analysis including fixed C and Total C  In1915 Ralston extended the study and found coal of equal Volatile matter(isovols) and equal calorific value(isocals) can be represented by straight lines in the triangle.
  13. 13. CLASSIFICATION BASED ON PROXIMATE ANALYSIS  Moisture, volatile matter, ash, fixed carbon content play the role of criteria  “fuel ratio” which is fixed carbon/volatile matter is used most 1. Roger’s classification:  in 1858 he divided coals into 4 groups on basis of %age V, M,Ash.
  14. 14. CLASSIFICATION BASED ON PROXIMATE ANALYSIS 2. Frazer’s classification:  In 1877, he used fuel ratio to classify coal as given:  Coals of lower rank than bituminous were not considered  Study was on only Pennsylvania coal. Sl no Coal type Fuel ratio 1. Anthracite 100-12 2. Semi anthracite 8-12 3. Semi bituminous 5-8 4. Bituminous 0-5
  15. 15. CLASSIFICATION BASED ON PROXIMATE ANALYSIS 3. Campbell classification:  also based on fuel ratio but all coals below 5 FR were taken as bituminous coal  In 1926, he combined fuel ratio to different characteristics for distinguishing lower rank coal. Sl no. Coal type fuel ratio 1. Anthracite 10-50 2. Semi anthracite 5-10 3. Semi bituminous 2.5-5 4. Bituminous <2.5
  16. 16. CLASSIFICATION INVOLVING BOTH PROXIMATE ANALYSIS AND CALORIFIC VALUE: 1. Parr’s classification:  He considered Volatile Carbon, Total Carbon, inert volatile matter and gross coal index(C+ available H+ S)  The basis was Volatile carbon X 100/Total carbon.  He gave a new classification in 1928, where he used following formula (indicated BTU-50S) X100  Unit B.T.U=--------------------------------------- 100-(1.08A +0.55S)
  17. 17. PARR’S CLASSIFICATION [V as determined-(0.8A+0.4S)]X 10  unit VM=------------------------------------------------ 100-(1.08A +0.55S) Class % unit VM Unit BTU Anthracite 0-8 15000-16500 semi Anthracite 8-12 15000-16500 Bituminous A 12-24 15000-16500 Bituminous B 25-50 15000-16500 Bituminous C 30-55 14000-15000 Bituminous D 35-60 12500-14000 Lignite 35-60 11000-12500 Peat 55-80 9000-110000
  18. 18. A.S.T.M. CLASSIFICATION  It classifies coal to 4 broad classes based on fixed carbon and calorific value (BTU) on dry mineral matter free basis.  Applicable only to vitrinite rich coal and excludes southern Gondwanaland coal  Gross Heating Value found on a moist and mineral matter free basis. Moist refers to the natural inherent water contained (MJ/kg X 430.11=Btu/lb).  Coals containing 69 wt % or more fixed carbon on a dry mmf basis are ranked according to their fixed carbon content regardless of their Gross Heating Value.
  19. 19. Class or Rank Group Fixed Carbon (wt % dry mmf) Volatile Matter (wt % dry mmf) Gross Heating Value (MJ/kg moist mmf) Equal or greater than Less than Greater than Equal or less than Equal or greater than Less than Anthracitic 1. Meta-anthracite 2. Anthracite 3. Semi-anthracite 98 92 86 98 92 2 8 2 8 14 Bituminous 1. Low-volatile bituminous 2. Medium-volatile bituminous 3. High-volatile A bituminous 4. High-volatile B bituminous 5. High-volatile C bituminous 78 69 ----- ----- ---- 86 78 69 ----- ---- 14 22 31 ---- ---- 22 31 ---- ---- ---- 32.55 30.23 26.74 24.41 32.55 30.23 26.74 Subbituminous Sub-bituminous A Sub-bituminous B Sub-bituminous C 24.41 22.09 19.30 26.74 24.41 22.09 Lignite Lignite A Lignite B 14.65 19.30 14.65
  20. 20. CLASSIFICATION BY NATIONAL COAL BOARD  Specifically designed for commercial use  Rank based  Uses 3 digit code to identify main class, class and subclass to which a coal belongs  Applicable to vitrinite rich coal  Volatile matter in dmmf basis and Gray-King coke type values are considered.
  21. 21. Class Volatile matter1) (weight %) General description 101 < 6.1 Anthracites 102 3.1 - 9.0 201 9.1 - 13.5 Dry steam coals Low volatile steam coals 202 13.6 - 15.0 203 15.1 - 17.0 Cooking steams coals 204 17.1 - 19.5 206 19.1 - 19.5 Heat altered low volatile steam coals 301 19.6 - 32.0 Prime cooking coals Medium volatile coals305 19.6 - 32.0 Mainly heat altered coals 306 19.6 - 32.0 401 32.1 - 36.0 Very strongly coking coals High volatile coals 402 > 36.0 501 32.1 - 36.0 Strongly coking coals 502 > 36.0 601 32.1 - 36.0 Medium coking coals 602 > 36.0 701 32.1 Weakly coking coals 702 > 36.0 801 32.1 - 36.0 Very weakly coking coals 802 > 36.0 901 32.1 - 36.0
  22. 22. INTERNATIONAL CLASSIFICATION OF HARD COAL  Mainly for anthracites and bituminous coal but covers fairly all kinds  Uses 14 digit code that defines 8 parameters namely 1. vitrinite reflectance 2. Reflectogram characteristics 3. Inertinite content 4. Exinite/liptinite content 5. Caking property(FSI) 6. 2 for VM 7. 2 for Ash 8. 2 for S 9. 2 for gross calorific value
  23. 23. CLASSIFICATION OF INDIAN COAL Scientific Coding of Indian Coal  3 basic parameters and 1 supplementary parameter  1st digit (1-9) corresponds to Calorific value (dmmf)  2nd (0-9) one Volatile matter (dmmf)  3rd (0-5)one Coke type  4th (1-6) one: Maximum thickness of plastic layer for Caking coal and M % for non caking.
  24. 24. GRADING OF INDIAN COAL  For grading of Non-Coking coal useful heat value is used, which is calculated by HU= 8900- 138(ash + moisture) kcal/kg 1. if M<2% and VM< 19% then deduct 150 kcal/kg for each 1% reduction in VM 2. M at 40 c and 60% RH  Grading does not include coal from North East India  Grading of coking coal is done as per their ash content
  25. 25. GRADING OF NON- COKING COAL Grade Useful heat value(kcal/kg) A >6200 B 5601-6200 C 4941-5600 D 4201-4940 E 3361-4200 F 2401-3360 G 1301-2400
  26. 26. GRADING OF COKING COAL Grades Ash content Steel I <15% Steel II 15-18% Washery grade I 18-21% Washery grade II 21-24% Washery grade III 24-28% Washery grade IV 28-35% Semi coking I <19%(A+M) Semi coking II 19-24%(A+M) Hard coke by product premium <25% Ordinary 25-30% Beehive premium <27% Beehive superior 27-31% Beehive Ordinary 32-36%
  27. 27. CLASSIFICATION FOR EXPORT PURPOSE Grade Low volatile High volatile Selected <13% A; >7000 cal <11% A; <6% M; >6800 cal First <15% A; >6500 cal <13% A, <9% M; >6300cal Second <18% A; >6000 cal <16% A;<10% M; >6000 cal Third --------------------------- ------------------------
  28. 28. REFERENCE  Sarkar S. (1988), “Fuels and Combustion”, Orient Longman Publication, 2nd edition, pp-71-85  Rose H.J.(1945),“Chemistry of Coal Utilisation”, John Wiley & Sons, Vol. I, pp 25-80  Berkowitz N (1994), “An Introduction to Coal Technology”, Academic Press, 2nd edition, pp-61-72  “Classification and Codification of Indian Coals and Lignite”, IS:770-1977  Krishnan M.S. (1940), “Classification of Coal”, Vol. III
  29. 29. THANK YOU

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