环管反应器内液固两相流的数值模拟

为了对环管反应器内液固两相的流动形态进行研究,建立以颗粒动力学为基础的Euler-Euler双流体模型。在浆液流速远大于自由沉降速度的情况下,模拟不同浆液入口速度时的环管反应器上升段压力降,同时对管道内液固两相流中的一些重要参数进行数值研究：在入口液固两相体积分布均匀的情况下,环管反应器上升段、弯管段以及下降段液固两相体积分布和液固两相速度均不一样,在弯管段由于离心力引起管道内二次流,使得固相颗粒甩向弯管的外侧壁,引起固相体积分数在弯管外侧壁明显增大,管道内固体颗粒相分布不均。在浆液速度v=3m.s-1时,液相和固相的速度有一定的速度差,随着入口速度增大,速度差变小;当浆液速度v=7m.s-1时,固体颗粒相速度分布与液相速度基本相同,两者之间的滑移速度可以忽略。计算结果与传统经验公式的比较表明模型能有效地描述环管反应器内压力降和反应器内浆液流动形态。

Numerical simulation of liquid-solid two-phase flow in tubular loop reactor

To study on the flow patterns of liquid-solid two-phase flow in tubular loop reactor,an Euler-Euler two fluid model based on the kinetics of granular was built to simulate liquid-solid two-phase flow.The mean pressure gradients were simulated at different slurry inlet velocity when the slurry inlet velocity was higher than the free settling velocity.Volume fraction and velocity distributions of liquid-solid two-phase flow are different at up-section,curve-section and down-section in tubular loop reactor.The secondary flow occurs when liquid and solid particles enter the curve-section of tubular loop reactor and solid particles flow towards wall by means of centrifugal force,which leads to un-uniform distribution of solid volume fraction.The slip velocity of liquid-solid is kept at slurry velocity v=3m.s-1.The slip velocity magnitude reduces with slurry velocity increasing and can be neglected at slurry velocity v≥7m.s-1.The comparison of numerical results with the calculated value of empirical equation for liquid-solid two-phase flow shows that the presented model is available to describe pressure gradients and slurry flow patterns in tubular loop reactor.