What is NOx?
NOx refers to nitrogen oxides (NO and NO2) produced during combustion. It is a major air pollutant contributing to smog and acid rain.
Formation Mechanisms
- Thermal NOx: Formed by the oxidation of atmospheric nitrogen at high temperatures (>1300°C).
- Fuel NOx: Formed from nitrogen bound in the fuel itself (common in heavy oil and coal).
- Prompt NOx: Formed early in the flame front by reaction with hydrocarbon radicals.
Mitigation Strategies
- Flue Gas Recirculation (FGR): Lowers flame temperature.
- Staged Combustion: Creates fuel-rich and fuel-lean zones to inhibit formation.
- Ultra-Low NOx Burners: Combine multiple techniques to achieve < 30 mg/Nm³.