涡耗散模型和混合分数模型模拟锅炉煤粉掺烧污泥过程的适应性

Adaptability of PDF transport model and eddy-dissipation model in simulation of coal combustion and co-combustion with sludge in coal-fired boiler

分别使用组分输运涡耗散模型(EDM)和混合分数PDF模型,对1台100 MW四角切圆锅炉燃烧煤粉和掺烧污泥时,进行炉内流动、燃烧和污染物NOx排放数值模拟研究。研究结果表明:2种模型均能较好地模拟单煤燃烧时炉膛内部温度场和速度场;模拟烟气组分O2和CO2体积分数相接近,均较符合实际情况;EDM方法能较好地模拟水分吸热对炉膛燃烧的影响,在锅炉掺烧不同含水率污泥的燃烧数值模拟方面相比PDF模型更加合理;对比实际锅炉掺烧含水率为56%的不同配比污泥,模拟结果与现场试验结果相符,表明EDM能合理地模拟不同比例的高水分污泥的掺混燃烧。

The numerical simulations using probability density function（PDF） transport model and eddy-dissipation model（EDM） were carried out to evaluate the characteristics of coal combustion and coal combined firing with sludge in a 100 MW tangentially coal fired utility boiler. The characteristics of flow, combustion and NOx emissions were studied.The results show that two models can both simulate successfully the temperature and velocity fields of the boiler for coal fired case; flue gas components like O2 and CO2 volume fractions are in line with the actual situation when these two kinds of model are adopted; H2 O concentration is better simulated using EDM than PDF model; the effects of moisture absorption of heat are simulated well for combustion characteristic of the boiler, and NOx emission is better simulated.For high moisture sludge co-combustion, EDM has more advantages. Compared with field test when moisture rate of sludge is 56% for different mass ratios of sludge co-combustion in the furnace, simulation results using EDM correspond well, which shows that EDM can effectively simulate the effects of co-combustion with different mass ratios and high moisture content of sludge.