煤中挥发氮析出过程模拟:不同热解模型的影响

The effect of various devolatilization models on the performance of numerical simulation of the formation of NO from the coal volatile nitrogen

采用数值模型研究了煤热解、燃烧过程中挥发分氮的析出、中间含氮产物HCN的生成以及转变为NO的过程 .分别采用双方程模型和通用模型描述热解过程 ,利用有限体积方法对质量、化学组分、动量和热量守恒方程进行离散求解 .计算结果表明两种模型获得的热解过程、孔隙率、HCN生成率等方面存在一定差别 ,而对颗粒着火时间、NO生成率等方面比较接近 .与试验结果比较 。

The particle model is employed to study the coal devolatilization, the release of volatile fuel-nitrogen, formation of HCN and the subsequent conversion to NO during the devolatilization process. The finite volume numerical scheme is used to solve the equations of mass, chemical species, momentum and heat transfer conservation about the coal particle. The two competing reactions and the universal devolatilization models are employed, the results from the various models are compared, which shows that there are differences existing in the data of porosity, HCN formation rate and the devolatilization process. The data of particle ignition time and the NO formation rate agree well together. Compared with the experimental data, the two competing reactions model is more suitable to model the formation of NO from the coal volatile nitrogen.