Study On Hydrodynamics And Mass Transfer Characteristics Of Two-stage Jet Loop Reactor

The loop reactor is a multiphase flow reactor developed from the bubble column.The loop reactor has a lot of advantages,such as simple structure,convenient operation,high mass transfer efficiency,and easy to be amplified in engineering.It has been widely used in chemical engineering,environmental engineering and biological engineering.Compared with the traditional single-stage loop reactor,the multistage loop reactor has a multistage guide tube,and the fluid can form a multistage circulating flow in the reactor,which has better mixing and mass transfer performance.In this paper,a two-stage jet loop reactor is proposed on the basis of single-stage jet loop reactor.The guide tube of the single-stage loop reactor is divided into two sections.Because of the upper stage gas ejection,the flow pressure drop between two stages is reduced,and the bubble breaking is accelerated.This paper focuses on gas velocity,liquid velocity,gas allocation and system properties,which play an important role in the changes of hydrodynamics and mass transfer characteristics.The results show that hydrodynamics and mass transfer characteristics increase significantly with the increase of gas velocity and liquid velocity;the change of the gas allocation improves the gas distribution in the reactor,and there is an optimal gas distribution,and the mass transfer coefficient reaches the maximum value;the proper improvement of the system properties of the loop reactor is beneficial to strengthen gas-liquid mass transfer process.According to the modified double film theory and the structure characteristics of the two-stage jet loop reactor,the empirical correlation of the volume mass transfer coefficient is obtained:kLa=(1.82 x 10-2O-2?ug+1.72×10-4uL+10-3)aEl+[1.82 × 10-2 ug +1 0-3]aE2Then software Fluent 6.3 has been used to simulate the gas-liquid two-phase flow in two-stage jet loop reactor.The trend of the numerical simulation values coincides with the trend of the experimental values,and the error is within 20%.The detailed flow field distribution is obtained.Finally,the influence of guide tube structure on the hydrodynamics of the reactor is investigated.The simulation results show that the change trend of the two stage gas holdup and the liquid velocity is consistent with the change of the diameter of the two stage guide tube,and the change trend of the two gas holdup and liquid velocity is exactly opposite with the change of the space of the two stage guide tube.