Numerical simulation of NO_x formation in a cyclone-opposed coal-fired utility boiler

摘要

In this paper, FLUENT software was used to simulate the burning process in a utility boiler. Chose the kinetics/diffusion-limited as combustion model, two-compet-ing-rates as devolatilization model, RNG k-εmodel as viscous model, and PDF model as combustion turbulent flow model. Numerical calculation of NO_x formation in a 330 MW cyclone-opposed coal-fired utility boiler with 32 double air registers was done. The distribution characteristics of temperature, NO_x and oxygen concentration in furnace were studied. They were symmetrically distributed in furnace. In the combustion area, temperature and NO_x concentration are high, while oxygen concentration is low. Temperature and NO_x concentration are declined gradually along with furnace height, while oxygen concentration is raised. The higher the temperature is and the greater the excess air coefficient is, the more NO_x formation.