撞击流气化炉内气固两相流动与颗粒附壁沉积数值模拟

Numerical Simulation of Gas-solid Two Phase Flows and Particle Deposition in Impinging Streams Gasifier

对多喷嘴对置式气化炉内复杂的气固两相流动与颗粒附壁沉积进行3D数值模拟。采用Realizable k-ε湍流模型计算炉内气相湍流流场,应用Euler-Lagrange模型模拟气固两相流动,颗粒轨迹跟踪采用随机轨道模型。根据液态排渣气化炉本身特点,描述炉壁熔渣流的形成过程,建立适用于液态排渣气化炉的颗粒附壁沉积模型,模拟结果与实验值吻合较好。模拟结果表明,数值模拟再现了撞击流气化炉内分区流动的情况;射流撞击使颗粒在气化炉内分布较为均匀,撞击中心和撞击流股区域浓度略高;颗粒在炉壁沉积基本覆盖整个气化炉,不存在局部积渣;当气化炉操作压力达到4.0MPa时,渣口气流夹带颗粒量有所提高,气流流速的增大而提高,颗粒停留时间缩短,影响碳转化率。

3D numerical simulation was conducted to investigate the gas-solid two phase flows and particle deposition in impinging streams gasifier. The realizable k-ε model was used to calculate the complex turbulent gas flow, Euler-Lagrange model was used to simulate turbulent gas-solid flows in the gasifier, while stochastic trajectory model was adopted to track particles trajectories. The formation process of furnace wall slag flow was described and the particle deposition model was established according to the characteristics of slag tap gas boiler, simulation results are consisted with experimental data. The results indicate that the numerical simulation can reproduce the flow field in impinging streams gasifier. Complex turbulence in impinging streams gasifier led to the particle concentration distribution is reasonable while the impinging region and impinging stream region are little higher. Slag coating are very uniform and coat all area in gasifier internal wall ultimately. Rate of particle deposition increased with the increase of inlet velocity at the same inlet particle concentration when the pressure of gasifier upto 4.0 Mpa, therefore residence time is shortened, and it effects carbon conversion.