CO₂ and SO₂ emission rate from fuel ultimate analysis and firing rate — exact stoichiometric mass ratios (complete combustion), the same combustion mass balance already used internally by the Boiler Efficiency (Indirect Method) calculator, surfaced here as a standalone figure.
Verified against published standard
Fuel Firing Rate & Ultimate Analysis
From the fuel's own ultimate/proximate analysis report (coal, oil, or gas). This calculates CO₂ and SO₂ only — NOx and particulate (SPM) emissions depend on combustion technology, flame temperature, and pollution-control equipment (ESP/FGD/SCR), not fuel composition alone, so they cannot honestly be derived from fuel analysis; real plants measure them directly with a CEMS (Continuous Emission Monitoring System).
Enter fuel flow, carbon %, and sulfur % to calculate.
About This Calculation
CO₂ and SO₂ emission rate follow directly and exactly from the fuel's own carbon and sulfur content via basic combustion stoichiometry (C + O₂ → CO₂, S + O₂ → SO₂) — the molecular weight ratios involved (44/12 for carbon→CO₂, 64/32 for sulfur→SO₂) are fixed chemistry, not plant-specific assumptions. NOx and particulate (SPM) emissions are deliberately NOT included here, because unlike CO₂/SO₂ they are not determined by fuel composition alone — they depend on combustion technology, flame temperature, staging, and whichever pollution control equipment (ESP, FGD, SCR/SNCR) is fitted, which is exactly why real plants measure them with a CEMS rather than calculating them from a fuel analysis report.
Frequently Asked Questions
Why is CO₂ basically un-reducible by combustion control, while SO₂ is not?
CO₂ emission is fixed entirely by how much carbon is burned — there is no combustion technique that reduces it for a given fuel and generation output, short of switching fuel or adding carbon capture (not yet standard on coal/gas thermal units). SO₂, by contrast, CAN be reduced after combustion by a Flue Gas Desulfurization (FGD) system, which is exactly why this calculator's SO₂ figure is explicitly the pre-control rate — actual stack SO₂ is lower wherever FGD is fitted and operating.
Why can't NOx be calculated the same simple way as CO2/SO2 from fuel analysis?
CO₂ and SO₂ come directly from oxidizing carbon and sulfur already present in the fuel — straightforward stoichiometry. NOx forms two genuinely different ways: from nitrogen already in the fuel (fuel NOx) AND from atmospheric nitrogen and oxygen reacting at high flame temperature (thermal NOx) — the second pathway depends on combustion temperature, staging, and residence time, none of which a fuel analysis report captures, which is why NOx requires either detailed combustion modeling or direct stack measurement, not a simple mass balance.
Is the calculated CO2/SO2 figure the actual measured stack value?
Not necessarily — this is the theoretical maximum from complete combustion of the fuel's carbon and sulfur content. Actual CO2 is essentially this figure (since combustion of carbon to CO2 is normally close to complete), but actual stack SO2 will read lower than this wherever an FGD system is capturing sulfur before the flue gas reaches the stack.