The exhaust gases generated by burning fuel or by a specific industrial process. In boiler applications, off-gases from a refinery or chemical plant are often piped into the burner as a secondary fuel to recover waste heat. They can have wildly varying heating values and chemical compositions, requiring specialized burner controls and continuous combustion analysis to burn safely.
We're running rich because the refinery off-gas spiked in methane content and the oxygen trim couldn't keep up.
Also heard as
- waste gas
Do not mix it up with
- Flue gas: Flue gas is the exhaust leaving the boiler, while off-gas is often a waste product from another process used as fuel.
Related terms
Flue gas
The hot exhaust that leaves the boiler after combustion, made up mostly of nitrogen, carbon dioxide, water vapor and leftover oxygen.
Burner
The assembly that mixes fuel with air and holds a stable flame to heat the boiler.
Combustion analysis
Testing a burner's flue gas for oxygen, CO, CO2 and temperature to set it up safely and efficiently.