3MW_(th)富氧燃烧煤粉锅炉的数值模拟研究

Numerical Simulation of Oxy-Fuel Combustion on 3 MWth Coal-Fired Boiler

以国内首台3 MW_(th)富氧燃烧煤粉锅炉为研究对象,借助CFD软件对煤粉空气燃烧和富氧燃烧工况进行数值模拟研究。通过与实验结果对比发现,模拟得到的炉膛温度分布、换热量以及出口组分与实验测量结果吻合,这表明本文使用改进的辐射特性模型以及4步化学反应机理能够很好地预测炉内温度、传热以及烟气组分分布。通过模拟研究,对比分析了空气燃烧与富氧燃烧的炉内特性。研究结果表明:富氧燃烧时,CO_2的显著增加使得燃烧器区域出现高浓度CO;富氧燃烧的整体温度分布与空气燃烧相似,但峰值温度有较大的降低;炉内辐射传热较空气燃烧略有下降。

This study uses a computational fluid dynamics(CFD) code to simulate the firing of coal under the conventional air combustion and oxy-fuel combustion in the first domestic 3 MW_(th)oxy-fuel combustion boiler.Compared with the experiment results,we found that the temperature distribution,heat transfer and gas component in the furnace outlet are in agreement with the measured data.This suggests that the improved radiation model and the 4-step chemical reaction used in this paper can well predict the temperature,heat transfer and gas component in furnace.Via simulation study,we analyze the furnace properties by comparing air combustion with oxy-fuel combustion.The results showed that,under the oxy-fuel combustion,high CO concentration appears in burner region because of the effect of high CO_2 concentration and the radiative transfer slightly decreases.It is clearly seen that a reduction in the peak temperature but the overall temperature distribution are similar to air combustion.