【摘要】 为了研究我国自主研发的两段式干煤粉气流床气化炉内熔渣壁面沉积规律,对该气化炉进行了三维数值模拟.在合理假设的基础上,建立了基于Eulerian-Lagrangian模拟方法的炉内湍流多相反应流动模型,采用Realizable k-ε模型计算炉内气相湍流流场,应用颗粒轨道模型随机追踪煤粉颗粒在湍流气流中的运动与壁面沉积过程.通过数值计算获得了炉内气相流场、煤粉颗粒运动轨迹及其浓度分布,以及熔渣颗粒在炉膛壁面上的沉积率分布,揭示了该炉型内熔渣颗粒壁面沉积特性,并分析了不同进料方式对熔渣壁面沉积的影响规律.结果表明:两喷嘴对置进料使得熔渣主要沉积在喷嘴高度处两喷嘴之间的壁面上;四喷嘴对置进料使得一段壁面熔渣沉积率高于两喷嘴进料时的熔渣沉积率,且沉积率在圆周上的分布更加均匀,有利于形成均匀渣层对壁面进行有效保护;四喷嘴切圆进料使得炉内几乎所有熔渣颗粒都沉积在炉膛壁面上,且停留时间较短.更多还原

【Abstract】 The 3D numerical simulation is conducted to investigate the slag desposition on the internal wall in a two-stage dry feed entrained-flow coal gasifier developed in China. A model based on the Eulerian-Lagrangian approach for the turbulent flow with multiphase reactions in the gasifier is proposed after reasonable hypotheses. The Realizable k-ε model is used to simulate the complex turbulent gas flow while the stochastic trajectory model is adopted to track coal particle trajectories and the particledeposition process. The flow field of the gas phase,the trajectories of coal particles,the concentration distribution of coal particles,and the slag deposition rate on the wall in the gasifier are obtained using the proposed model. The slag deposition characteristics on the gasifier wall in the entrained-flow coal gasifier are revealed,and the effects of the feeding mode on the slag deposition on the internal wall are numerically analyzed. The results indicate that the feeding mode with two opposed nozzles makes the majority of slag particles deposit on the wall areas between the injectors at the injector height. The feeding mode with four opposed nozzles makes the slag deposition rate on the wall of the first stage higher than that of the feeding mode with two opposed nozzles and makes the deposition distribution more uniform along the circumference,which is good for the formation of uniform slag layer to protect the wall. The feeding mode with four nozzles for tangential firing makes almost all the particles deposit on the wall with very short residence times.更多还原