Low nox burner process for boilers

摘要

Process is described for reducing emissions of nitrogen oxides and carbon monoxide from fuel gas fired boilers by using a computer to closely control the flow rate of combustion air and by installing a duct to allow flue gas to recirculate into the air intake of the boiler. In most cases strict emission standards can be met without making any other mechanical modifications to the boiler. A computer controller maps burner characteristics and controls both a variable speed drive and the damper on the combustion air fan, and a damper on recirculated flue gas to meet emission requirements over the various firing rates while maintaining a stable flame free of pulsations. In some burners a simple cone structure placed in the burner provides additional flame stability.