Flue Gas Excess Air & Oxygen Calculator
Calculate boiler excess air from flue gas dry oxygen (O2) or carbon dioxide (CO2) readings and optimize burner air-to-fuel ratios across industrial fuels.
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Excess Air & Burner Tuning
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Frequently Asked Questions
Why is excess air required for industrial burners?
Real burners cannot achieve instantaneous, perfect molecular mixing of air and fuel in the combustion zone. Excess air (typically 10% to 20% above stoichiometric) provides sufficient extra oxygen molecules to ensure every carbon atom fully combusts to CO2 rather than poisonous CO or unburned soot.
How does flue gas O2 relate mathematically to Excess Air?
Because ambient air is 20.9% oxygen, the excess air percentage is calculated directly as %EA = [%O2 / (20.9 - %O2)] × 100%. For example, 3.5% dry O2 corresponds to [3.5 / (20.9 - 3.5)] × 100% = 20.1% excess air.
What is an automatic oxygen trim control system?
An oxygen trim system uses a zirconium oxide sensor in the exhaust stack to continuously modulate the combustion air damper. This compensates automatically for day-to-night changes in ambient air density, humidity, and fuel heating value, locking excess O2 at optimal efficiency.