How do flue gas analyzers (e.g., O2, CO, NOx) inform adjustments to combustion control?

Flue gas analyzers provide real-time information about the composition of the exhaust gases produced during combustion, enabling operators to make informed adjustments to combustion control for optimal efficiency and emissions. Oxygen (O2) analyzers measure the amount of excess air present in the flue gas. High O2 levels indicate too much excess air, which leads to heat loss and reduced efficiency. Adjusting the air-to-fuel ratio by decreasing airflow reduces excess air and improves efficiency. Low O2 levels suggest insufficient air, which can lead to incomplete combustion and increased emissions of carbon monoxide and unburned hydrocarbons. Carbon monoxide (CO) analyzers detect the presence of CO, a product of incomplete combustion. High CO levels indicate that not all the fuel is being fully burned due to insufficient air, poor mixing, or low combustion temperatures. Increasing airflow, improving mixing through adjustments to air dampers, or increasing combustion temperature can reduce CO emissions. Nitrogen oxides (NOx) analyzers measure the concentration of NOx, a regulated pollutant formed during high-temperature combustion. High NOx levels may require adjustments to the combustion process to reduce peak temperatures or implement staged combustion techniques. This could involve reducing overall air flow, using overfire air (tertiary air) to lower temperatures in certain zones, or recirculating flue gas to lower the oxygen concentration and temperature. Continuous monitoring and analysis of O2, CO, and NOx levels allow for dynamic optimization of combustion parameters, resulting in improved boiler efficiency, reduced emissions, and stable operation.