关键词: 煤粉燃烧器, 燃烧模拟, 煤粉粒径, 排放特性

Abstract: Pulverized coal used as fuel of burner in the process of aggregate drying had the significant economic and comprehensive benefits. However, pulverized coal combustion generated a variety of noxious gases which polluted the atmosphere. Effective reduction of pollutant emission was significant for pulverized coal burner’s industrialization and became an important issue in coal combustion. Pulverized coal particle size affected the turbulence, diffusion and coupled motion of internal flow field in pulverized coal burner, thus affected its emission characteristics. Based on the technology of aggregate drying and followed the essential mechanism of coal combustion, a three-dimensional physical model was established by the modeling software CREO. Computer aided engineering software Gambit was used to make unstructured mesh generation for the pulverized coal burner. Control model of pulverized coal combustion behavior was constructed to simulate the internal fields of aggregate drying pulverized coal burner in Fluent software. The standard k?? model was used to describe the turbulent motion of turbulent flow in the process of pulverized coal combustion, and the P1 radiation model was used to describe the phenomenon of thermal radiation and heat transfer between solid phase and air phase. The stochastic particle trajectory model was used to describe the dispersion of discrete phase and the eddy dissipation model was used to describe the motion and combustion of turbulent eddy. The kinetics/diffusion-limited model was chosen as the combustion model in process of pulverized coal combustion. The influence of pulverized coal particle size on emission characteristics during pulverized coal combustion process in aggregate drying was analysed with the pollutant mass fraction as the evaluation standard. The results showed that with the increase of particle size, because of incomplete combustion of pulverized coal, the CO emission increased and the CO2 emission declined. With the increase of particle size, the emission of SO2 grew, the optimal emission of NO was when pulverized coal particle size was 100 μm.

Key words: pulverized coal burner, combustion simulation, pulverized coal particle size, emission characteristics