CHEMISTRY




Lignite Coal Sub-Bituminous Coal Peat Coal Bituminous Coal Anthracite



Coal and Coke Calculation Protocols
*** Net CV calculation - refer to ASTM D5865 / ISO 1928
*** Moisture conversion to different bases - refer to ASTM D3180 / ISO 1170

1. Bases Conversion Factors:

  • Ref: ASTM D3180 / ISO 1170 - Conversion to different moisture bases
  1. Dry factor (converts AD to Dry) (100-ADM)/100
    Dry = AD / ((100-ADM)/100)
  2. AR factor (converts Dry to AR) (100-TM)/100
    AR = Dry x ((100-TM))/100)
  3. DAF factor (converts Dry to DAF) (100-Dry Ash)/100
    DAF = Dry / ((100-Dry Ash)/100)
  • Where:
    TM = Total Moisture
    ADM = Air Dried Moisture (Moisture in the Analysis Sample)
    AR = As Received Basis
    AD = As Determined (Air Dried) Basis
    Dry = Dry Basis
    DAF = Dry Ash Free Basis

2. Two Stage Total Moisture Formula (Refer to ASTM / ISO):

  • Two stage total moisture determination is used when the coal sample is too wet to divide or crush without the potential of loosing significate amounts of moisture.

    TMar, % = [RMad, % x (100 - FMad, %) / 100] + FMad %

    M = Total moisture; FM = Free Moisture; RM = Residual moisture

3. Calorific Value Conversion Factors:

  • MJ/kg = kcals/kg / 238.846
  • MJ/kg = Btu/lb / 429.923
  • kcal/kg = MJ/kg x 238.846
  • kcal/kg = Btu/lb / 1.8
  • Btu/lb = MJ/kg x 429.923
  • Btu/lb = kcals x 1.8

4. CO2 Emission Factor:

  • t/CO2/TJ = As Received Carbon x 3.667 x [10,000/NCV(p)] in kJ/kg= As Received Carbon x 3.667 x [2388.46/NCV(p)] in kcal/kg

5. Fuel Ratio:

  • Fuel Ratio = Fixed Carbon / Volatile Matter.

6. Hydrogen in Coal, Refer to ASTM 3180 / ISO 1170:

  • In-as-much as hydrogen values may be reported on the basis of containing or not containing the hydrogen in water (moisture) associated with the sample, alternative conversion procedures are defined below:
  • Use following conversions to report H, including or excluding H in moisture. Total Hydrogen as-determined (ad): includes H in the moisture analysis.
  1. Hydrogen (excluding H in moisture):
    H(dry base) = [Total Hydrogen(ad)-(AMx0.1119)] x (100/(100-AM))
  2. Hydrogen (including H in moisture):
    H(ar) = [Total Hydrogen(db) x ((100-TM)/100)]+(0.1119*TM)
  3. ISO 1170 reports H as air-dried basis excluding H in the analysed moisture:
    H(air-dried) = Total Hydrogen(as-determined) - (Analysis Moisture x 0.1119)
    Hydrogen and Oxygen Factors based on the atomic weight of H20
    Hydrogen = Moisture X 0.1119
    Oxygen = Moisture X 0.8881

7. Net Calorific Value (NCV) Conversion Factors:

  • Ref: Net Calorific Value (ASTM D5865-03).
  • The heat produced by combustion of a substance at a constant pressure of 0.1 Mpa (1 Atm), with any water formed remaining as vapour.
  • ISO 1928-1995 at constant volume.
    Qv, net,m,J/g =( Q gr,v,d - 206.0 [ wHd ] ) x (1-0.01xMT) - (23.05x MT)
    Qv, net,m,kcal/kg = ( Q gr,v,d - 49.20 [ wHd ] ) x (1-0.01xMT) - (5.51x MT)
  • ISO 1928-1995 at constant pressure.
    Qp, net,m,J/g = { Q gr,v,d - 212.2 [ wHd ] - 0.8 x [wOd + wNd] } x (1- 0.01MT) - 24.43 x MT
    Qp, net,m,kcal/kg = { Q gr,v,d - 50.68 [ wHd ] - 0.191 x [wOd + wNd] } x (1- 0.01MT) - 5.84 x MT
    [ wHd ] = H content of the sample less Hydrogen present in the moisture
    w(H)d = w(H) x 100/100-MT
    MT= Total Moisture
  • ASTM 5865/3180 at constant pressure
    Qp(net)ar,J/g = Qvar(gross) - (215.5 x Har)
    Qp(net)ar,Btu/lb = Qvar(gross) - (92.67 x Har)
    Qp(net)ar,kcal/kg = Qvar(gross) - (51.47 x Har)
    Har = total hydrogen where hydrogen includes hydrogen in Sample Moisture
    Har = [(Had-0.1119xMad) x (100-Mar)/(100-Mad)] + 0.1119 x Mar

8. Seyler's Formula:

  • Various parameters of Coal can be estimated from the Ultimate Analysis and Calorific Value determinations, using Seyler's formula, and other similar calculations (e.g. Dulong's formula).
  • Reference:
    * COAL -Typology -Physics -Chemistry -Constitution
    D.W. Van Krevelen (third edition 1993) Page 47
    VMdaf = 10.61Hdaf - 1.24Cdaf + 84.15
    Hdaf = 0.069 (Qdaf/100+VMdaf) - 2.86
    Cdaf = [0.59 (Q,daf/100 - 0.367VMdaf) + 43.4]
    ** ISO 1928-1995 Part E.3.3

    Estimate of the hydrogen content, calculated using Seyler's Formula
    wH = 0.07 x w(V) + 0.000165 x qv,gr,m - 0.0285 x [ 100 - MT - w(A)
    w(H) - is the H content of sample less H contained in moisture, as % mass
    w(V) - is the VM content of sample with moisture content MT, as % mass
    w(A) - is the ash content of sample with moisture content MT, as% mass
    qv,gr,m - is the gross CV of sample with moisture content MT, in joules/g

    Note.1** Only valid when the calculated Hdb is greater than 3%

    Note.2* Only valid when the Odaf content is less than 15%

    Note.3 Can give erroneous results if coal shipments are a blend of low and high rank coals

9. Dulong's Formula

  • GCV(db) = 333xC(db) + 1442(H(db) - O(db) / 8) + 93xS(db)
    GCV is in (kJouls/kg dry basis). C, H, O, S as percent on a dry basis