Calculator Inputs
Formula Used
This calculator uses ultimate analysis to estimate the stoichiometric oxygen requirement per kilogram of fuel. Convert mass percentages to kmol of elements per kg fuel, then apply:
- nC = (C/100) / 12.011
- nH = (H/100) / 1.008
- nO = (O/100) / 16.000
- nS = (S/100) / 32.065
- nO2 = nC + (nH/4) + nS - (nO/2)
- nAir = nO2 / 0.21 (dry air contains 21% O2 by moles)
- mAir = nAir * 28.965
- V(NTP) = nAir * 22.414
- Actual air = Stoichiometric air * (1 + Excess/100)
- V(actual) = nAir * R * T / P (ideal gas, kPa*m3 units)
If your fuel is a pure hydrocarbon, you can approximate the ultimate analysis from its chemical formula. For fuels with high oxygen content, calculated O2 may reduce significantly.
How to Use This Calculator
- Enter the fuel mass you plan to burn on a consistent basis.
- Provide ultimate analysis percentages for C, H, O, and S.
- Set an excess air percentage for your burner operation.
- Enter air temperature and pressure to estimate actual volume flow.
- Press Calculate to view results above the form.
- Use the CSV or PDF buttons to save your calculation.
Tip: Use dry basis values if your lab report provides them. Moisture and ash are shown for completeness, but they do not change the oxygen balance in this simplified model.
Example Data Table
| Fuel basis | C (%) | H (%) | O (%) | S (%) | Excess air (%) | Stoich air (kg/kg) | Actual air (kg/kg) | Actual air volume (m3/kg at 25 C, 101.325 kPa) |
|---|---|---|---|---|---|---|---|---|
| 1.0 kg | 75 | 5 | 10 | 2 | 15 | 9.9798 | 11.4768 | 9.6917 |
Example is illustrative for a generic solid fuel analysis and common operating excess air.