Numerical Simulation Of Two-Phase Flow In Cyclone Reactor For Refinery Gas Desulfurization

With sulfur crude processing capacity increased year by year and increasingly strict environmental requirements,the existing refinery desulfurization equipment has some problems,such as its low desulfurization degree,high energy consumption and cost.So it is necessary to develop the small and integrated desulfurization equipment.This paper is based on the thinking of integrated absorption-separation,and applies the cyclone reactor to refinery gas desulfurization.By means of numerical simulation,the distribution of gas-liquid two-phase flow in reactor cyclone as well as the law of liquid phase migration is studied.Also it studies the influence of structure parameters,operating parameters and physical parameters on the flow characteristics of gas-liquid two-phase flow in the reactor.These provide theoretical guidance for structure optimization of cyclone reactor with integration of absorption-separation processes for refinery gas desulfurization.Firstly,the Mixture model was used to study the distribution of gas-liquid two-phase flow in the cyclone reactor.The axial velocity and tangential velocity of the gas phase in the mixing chamber and the separation chamber are all symmetrical.The liquid phase volume fraction of each cross section in the mixing chamber is uniformly distributed along the z axis.At the bottom of the mixing chamber,the liquid phase wall downward phenomenon occurs.The liquid phase volume fraction of each cross section in the separation chamber is the largest in the side wall and it gradually decreases from outside to inside.And liquid holdups are very small for most of the region which takes air center as the center.Secondly,it studies on the cyclone reactor to optimize its structure.The results show that when the insertion depth of exhaust pipe is 180 mm,the position of guide vane is 30 mm and the length of separation chamber is 700 mm,the distribution of liquid volume fraction in the cross section is more uniform,it is helpful for gas-liquid contact and mixing;the liquid phase volume fraction in the separation chamber is a gradient distribution of small in the center while large in the edge wall,it is more conducive to the separation of gas and liquid.Based on it,when the velocity of gas inlet is 10m/s,the concentration gradient of mixing chamber is smaller in the same cross section along the radial direction and the distribution of liquid phase is more uniform;when the velocity of liquid inlet is 1m/s,the tangential velocity in cyclone reactor is larger,the distribution of liquid phase in the mixing chamber is more uniform,and the distribution of liquid phase in the separation chamber is more concentrated at the side wall,but the droplet diameter has little effect on that.Finally,the distribution variation of droplet diameter with the residence time in the mixing chamber was studied by using the unsteady DPM model.The results show that the time is 0.25 s,the droplets in different diameters have occupied the entire space of the mixing chamber,some began to enter into the separation chamber;the liquid drops are centered in the lower part of the mixing chamber displaying ringed distribution when the residence time is 0.4s.In addition,the steady DPM model was used to study the droplet trajectories under different particle diameters,the droplet trajectories of 40?m are simpler and in a spiral,there is no back mixing phenomenon,the ratio of discharge from the down outlet is up to 82%,and its separation efficiency is higher.