煤粉粒径对骨料烘干煤粉燃烧器排放特性的影响

Effect of pulverized coal particles on emission characteristics of aggregate drying pulverized coal burner

构建骨料烘干煤粉燃烧器内煤粉燃烧行为的控制模型,以污染物含量为评价标准,研究了骨料烘干煤粉燃烧过程中煤粉粒径对排放特性的影响规律.结果表明,随煤粉粒径增大,煤粉在燃烧器内燃烧不充分,CO排放量增加,CO2排放量逐渐减少,SO2排放量增加,NO排放量在煤粉粒径为100mm时最小.

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-ε model was used to describe the turbulent motion of turbulent flow in the process of pulverized coal combustion,and the P 1 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 100μm.