新型干煤粉气化炉数值模拟研究

Numerical Study of New-Type Dry Pulverized Coal Gasifier

针对一种新型气渣分流式干煤粉气化炉进行数值模拟研究,利用数值模拟方法对新型气化炉进行三维建模,采用Realizable k-ε模型封闭湍流方程,应用随机轨道模型计算煤粉颗粒流流动,利用未反应核缩芯模型和涡扩散模型(Eddy-dissipation concept,EDC)分别模拟颗粒表面的化学反应和均相反应过程,采用P1辐射模型考虑了热辐射气体的辐射传热作用。研究结果表明:新型气化炉采用中上部多喷嘴干煤粉切向进料,炉内涡旋流动明显,流场十分复杂,颗粒在气流夹带和离心力作用下甩向壁面沉积形成液态渣膜,干煤粉气化反应在高温、高压下几乎瞬间完成,炉内温度分布和气体组分分布吻合。

A comprehensive three-dimensional numerical model is developed for simulation of the industrial scale new-type gasifier. The dry pulverized gasification process is divided into several submodels. The Realizable k-e model is applied to close the Reynolds-averaged Navier- Stokes equation for gas phase, and the Random-Trajectory model is used to simulate the be- havior of particle flow in gasifier. Water evaporation, coal pyrolysis, and homogeneous and heterogeneous char reactions are all considered. The P1 model is adopted to calculate the radi- ative heat transfer in gasifier. The numerical model is performed to simulate the industrial scale new-type gasifier, the predicted results indicated that the coal particle enrich on the wall above the burner and bottom of gasifier, the particle is effected by centrifugal force, so steady slagging flow can be formed on the surface of the cold-water wall. Furthermore, the eddy effect also led the particle flow to the wall of gasifier and deposited, and the slag formed on the wall of gasifier will molted and flow down from the top of gasieir. Temperature and syngas composition distribution in the gasifier is agreed well. Key words：