Numerical simulation of NOx emission characteristics during combustion in 350 MW supercritical cogeneration tangentially boiler

Abstract

In light of a 350 megawatt supercritical cogeneration tangential boiler, the combustion and the nitrogen oxides release mechanism in the furnace were numerically simulated. The combustion characteristics were analyzed, and the influencing factors, such as the pulverized coal concentration, the velocity of separated over-fire air and the boiler load, on nitrogen oxides release in the furnace were also systematically studied. The results show that the central airflow in the furnace rises spirally, and an inverted ?V? type temperature distribution is formed. The generation of nitrogen oxides can be effectively restrained by increasing the concentration of pulverized coal properly. Compared with the conventional concentration, the concentration of nitrogen oxides at the furnace exit can be reduced by 29.63% by taking high pulverized coal concentration. The concentration of NOx at the furnace exit can be drastically reduced by increasing the velocity of separated over-fire air. When decreasing boiler load, the concentration of NOx at furnace exit declines at first and then increases.