超短接触旋流反应器混合腔内气固混合特性的数值模拟

采用欧拉双流体模型对超短接触旋流反应器内的气固两相流场进行了数值模拟，主要研究了混合腔内固相的体积分数分布情况。计算结果表明：混合腔内的气流在切向进气的作用下得到了一定的混合加速效果，切向的高速射流有效地缩短了气固停留时间，保证短接触反应效果。通过对两种不同混合腔结构反应器的对比计算发现，在相同入口速度条件下结构2（切向进气管位于混合腔顶部）较结构1（切向进气管位于混合腔下部）气固停留时间短，由于切向气流的迅速作用，增加了混合腔内的湍动强度，使催化剂颗粒迅速有效扩散、增强气固接触效果而更有利于催化裂化反应的进行，更易实现短接触操作要求。计算结果与实验测量结果的比较表明模型能有效地描述超短接触旋流反应器内气固两相流动形态。

Numerical simulation on gas-solid mixing characteristics in mixing cavity of quick-contact cyclone reactor

Gas-solid two-phase flow of the quick-contact cyclone reactor was simulated with the Eulerian model,and especially the volume fraction of solids in the mixing cavity was researched.The results showed that tangential gas admission accelerated the gas speed in the mixing cavity,and it had a great impact on shortening gas-solid residence time and ensuring short contact reaction effect.For two mixing cavity structures,the second reactor(tangential intake pipes were fixed at the top of the mixing cavity)had a shorter residence time at the same inlet velocity,and it was more likely to achieve the short contact requirement.Solid particles of the first reactor(tangential intake pipes were fixed at the bottom of the mixing cavity)spreaded outward in the mixing cavity from the bottom of the feed inlet,with nearly no particle moving to the center space,and the concentration gradient was obvious.Then under the action of tangential flow,solids spreaded evenly,and tangential flow had a beneficial effect on the spreading of solids.In the second reactor,axial feeding contacted with the tangential flow in the mixing cavity at once under the action of tangential flow,and solid particles were evenly distributed,enhancing the contact effect of gas-solid two-phase.The flow state of gas-solid in the separation cavity of two different structures had no difference.Solid particles gathered on the wall of the reactor because of centrifugal force,and then flowed down around a spiral.In a word,turbulent diffusion of tangential gas admission increased turbulent intensity,and it had a beneficial effect on spreading the catalyst particles effectively,enhancing gas-solid contact effect.Due to tangential gas admission,the second reactor was better for the FCC reaction because of the solid particles spreading more evenly.The comparison of the numerical results and the experimental results showed that the present model was capable to describe the flow pattern in the reactor.This work could offer a basis for the structure optimization and enhanced efficiency of the quick-contact reactor.