Fuel F-factors are used to characterize the products of complete atmospheric combustion for a given amount of heat released. These factors are quite consistent, despite the variability of fuel density, ash and moisture.
The Fc-factor is the ratio of the carbon dioxide volume generated by the combustion of a given fuel to the amount of heat produced. The Fd factor is the ratio of the stoichiometric volume of dry gas generated for complete combustion of a given fuel with air to the amount of heat produced. The Fw factor is the ratio of the stoichiometric volume of wet gas generated for complete combustion of the fuel with dry air, to the amount of heat produced.
In the context of CO2 CEM systems, F factors are used to a) to determine CO2 emissions by monitoring O2 levels and stack gas flow rates, and b) to determine indirectly moisture levels in systems where stack gas CO2 levels are measured on a dry basis.
Note that the reference conditions for the F-factors are 25°C and 101.325 kPa. Where the results are compared with data generated at other reference conditions, the data must be compensated.
The F-factors for specific fuels provided in Table A-1 shall be used. For fuels not listed in Table A-1, F-factors shall be calculated according to Section A.3.
Table A-1 F-factors for Selected Canadian Fuels
| Fuel | Type | Oxygen-based F-factor | Carbon dioxide-based F-factor (Fc) (Sm3/GJ)* |
|
|---|---|---|---|---|
| Fd, dry basis (DSm3/GJ)* | Fw, wet basis (WSm3/GJ)* | |||
| Coal | Anthracite | 277 | 288 | 54.2 |
| Bituminous | 267 | 286 | 49.2 | |
| Sub-bituminous | 263 | 301 | 49.2 | |
| Lignite | 273 | 310 | 53.0 | |
| Oil | Crude, residual, or distillate | 255 | 289 | 39.3 |
| Gas | Natural | 240 | 295 | 28.4 |
| Propane | 238 | 281 | 32.5 | |
* Sm3 denotes one standard cubic metre (i.e., 1 m3 at 101.325 kPa and 25°C);
GJ = 1 000 000 000 Joules.
For EGUs simultaneously burning a combination of fossil fuels, a combined F-factor shall be calculated using Equation A-1.
Equation A-1
where:
Fm = combined F-factor
Xi = fraction of the total heat input from fuel i
Fi = appropriate F-factor for fuel i
n = number of fuels burned
For fuels not listed in Table A-1, F-factors shall be calculated using the ultimate analysis and higher heating values (HHV). Equations A-2, A-3 and A-4 shall be used to calculate the various F-factors.
Note: The %H2O term must be omitted in the equation for Fw if %H and %O include unavailable hydrogen and oxygen in the form of H2O.
where:
Fd, Fw, Fc = volumes of combustion components per unit of heat content in m3/GJ, at 25°C and 101.325 kPa
%H, %C, %S, %N, %O, %H2O = concentrations of hydrogen, carbon, sulphur, nitrogen, oxygen, and water, respectively in weight percent, as determined, and measured on the same wet or dry basis as the HHV in accordance with:
1) the following applicable ASTM standards:
i. ASTM D3176-09 entitled “Standard Practice for Ultimate Analysis of Coal and Coke”,
ii. ASTM D5291-10 entitled “Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants”,
iii. ASTM D1945-03 (2010) entitled “Standard Test Method for Analysis of Natural Gas by Gas Chromatography”,
iv. ASTM D1946-90 (2011) entitled “Standard Practice for Analysis of Reformed Gas by Gas Chromatography”, or
2) if those ASTM standards do not apply, an applicable internationally recognized method.
HHVd, HHVw = higher heating value of dry or wet fuel in kJ/kg to be measured in accordance with:
1) any of the following applicable ASTM or GPA standards:
i. ASTM D5865-11a entitled “Standard Test Method for Gross Calorific Value of Coal and Coke”,
ii. ASTM D5468-02 (2007) entitled “Standard Test Method for Gross Calorific and Ash Value of Waste Materials”,
iii. ASTM D240-09 entitled “Standard Test Method for Heat of Combustion of Liquid Hydrocarbon Fuels by Bomb Calorimeter”,
iv. ASTM D4809-09a entitled “Standard Test Method for Heat of Combustion of Liquid Hydrocarbon Fuels by Bomb Calorimeter (Precision Method)”,
v. ASTM D1826-94 (2010) entitled “Standard Test Method for Calorific (Heating) Value of Gases in Natural Gas Range by Continuous Recording Calorimeter”,
vi. ASTM D3588-98 (2003) entitled “Standard Practice for Calculating Heat Value, Compressibility Factor, and Relative Density of Gaseous Fuels”,
vii. ASTM D4891-89 (2006) entitled “Standard Test Method for Heating Value of Gases in Natural Gas Range by Stoichiometric Combustion”,
viii. GPA Standard 2172-09 entitled “Calculation of Gross Heating Value, Relative Density, Compressibility and Theoretical Hydrocarbon Liquid Content for Natural Gas Mixtures for Custody Transfer”,
ix. GPA Standard 2261-00 entitled “Analysis for Natural Gas and Similar Gaseous Mixtures by Gas Chromatography”, or
2) if those standards do not apply, an applicable internationally recognized method.
104 = conversion factor in kJ/GJ/100
Khd = 22.97 Sm3/kg, volume of dry exhaust gases resulting from the stoichiometric combustion of hydrogen in the fuel
Kc = 9.75 Sm3/kg, volume of dry exhaust gases resulting from the stoichiometric combustion of carbon in the fuel
Ks = 3.65 Sm3/kg, volume of dry exhaust gases resulting from the stoichiometric combustion of sulphur in the fuel
Kn = 0.87 Sm3/kg, volume of dry exhaust gases resulting from nitrogen in the fuel
Ko = -2.89 Sm3/kg, volume of dry combustion gases avoided due to oxygen in the fuel
Khw = 35.10 Sm3/kg, volume of wet exhaust gases resulting from the stoichiometric combustion of hydrogen in the fuel
Kw = 1.36 Sm3/kg, volume of water vapour resulting from the water contained in the fuel
Kcc = 2.04 Sm3/kg, volume of carbon dioxide produced during the complete combustion of the fuel
