Overview

Flue gas recirculation reduces the content of fresh air in the gas that is injected at the secondary air injection level. This allows the combustion process to proceed with less excess air, without increasing the combustion chamber temperature or CO concentration. Flue gas is extracted downstream of the dust separation equipment, e.g. electrostatic precipitator or fabric filter, and blown back into the combustion chamber.

The recirculation causes a very effective mixing of the flue gases and increases boiler efficiency by up to 3%, and the flow of flue gas after the extraction point is reduced by approximately 20%. Both effects depend on the calorific value of the waste and the thermal load at which the incinerator is operated. NO_x loads in the raw gas after recirculation extraction are significantly lower with flue gas recirculation.

Application