激冷室内气体穿越液池过程气液固三相的数值模拟

水煤浆气化炉激冷室内合成气穿越液池过程是复杂的气液固三相的流动过程,该过程起到合成气的进一步冷却及其所含凝渣捕集的作用。将欧拉和拉格朗日方法相结合,用VOF模型跟踪气液界面,用直接模拟蒙特卡罗方法(DSMC)计算颗粒碰撞。对含渣气体穿越液池的气液固三相流动过程进行了数值模拟,探讨了不同粒径、气流速度以及下降管出口淹没深度对气液流场以及对固体颗粒分离的影响。研究表明:气体出下降管后做流动方向急剧突变的流动,穿越过程气液形成具有一定周期的波状流动;含尘气体穿越液池过程对颗粒具有较高的捕集效率;颗粒的捕集效率随着粒径的增大而提高;随着气流出流速度以及下降管出口淹没深度的增加,液体的扰动加强,产生更多的液滴,有助于颗粒捕集效率的提高,但气流速度及淹没深度对颗粒捕获效率的影响逐渐减弱。

A Gas-liquid-solid Three-phase Numerical Simulation of the Syngas Passing Through a Cistern in a Quench Chamber

A syngas passing through a cistern in the quench chamber of a coal slurry gasifier pertains to a sophisticated gas-liquid-solid three-phase flow process,which functions to further cool the syngas and capture and collect the slag contained therein.By combining the Euler method with Lagrange one,the authors have calculated particle collisions by using a direct simulation Monte Carlo's (DSMC) method and employing VOF model to track the gas-liquid interface.A numerical simulation was conducted of the gas-liquid-solid three-phase flow process of slag-laden syngas passing through a cistern.An exploratory study has been performed of the influence of the following factors on the gas-liquid flow field and separation of solid particles: particle diameter,gas flow velocity and submerged depth of the downcomer at the outlet.The research results show that the syngas undergoes an abrupt change in flow direction after it leaves the downcomer and the formation of gas and liquid exhibits a periodic wave-shaped flow pattern.The dust-laden gas,when it passes through the cistern,features a relatively high particle-capture efficiency.An increase in particle diameters can also enhance the particle capture efficiency.With an increase of gas flow velocity and submerged depth of the downcomer at the outlet,the perturbation of the liquid intensifies,producing more liquid drops and contributing to an enhancement of particle-capture efficiency.The influence of gas flow velocity and submerged depth of the downcomer on the particle-capture efficiency,however,will be gradually weakened.