Effects of Tertiary Air Staged Combustion on NOx Emission Characteristic in a Pulverized-Coal Boiler with Swirl Burner

摘要

Air-staged combustion which moves parts of the jet of tertiary air to the top of Primary combustion zone for reducing the generation of NOx in a 300 MW pulverized-coal boiler with Swirl Burner. The primary purpose of this work is to investigate the effect of moving parts of the jet of tertiary air and changing the ratio of tertiary air on the distribution of temperature, the efficiency of combustion and the emission of NOx. When the ratio of upper tertiary air is increasing, the concentration of NOx is decreasing, but the carbon content in fly ash is increasing and it will affect the efficiency of combustion. Comprehensive comparison of all projects, when the ratio of upper tertiary air is 70%, the carbon content in fly ash is 3.31% and the emission concentration of NOx in the export of air preheater can decrease to 767mg/Nm~3.