3D CFD Simulation Of Gas-liquid Flow And Mass Transfer In Novel Reactors

Compared with traditional chemical reactors,the novel process intensified equipment such as micro-reactors,high-gravity reactors,etc.have attracted great attention in academic research and industrial applications because of their remarkable features such as energy consumption reduction.Due to the complexity of internal structure and multiphase flow in these reactors,the basic research was relatively scarce.Based on the results of previous studies,the microporous tube-in-tube-microreactor(MTMCR)and rotating packed bed(RPB)were adopted as research objects and established three-dimensional CFD models of gas-liquid flow and mass transfer in the reactors.The high-speed camera was used to obtain the gas-liquid flow pattern in the MTMCR.The influence of operating conditions and structural parameters on the gas-liquid flow and mass transfer process was studied,which provided a theoretical basis for extending the industrial application of the reactors.The main results are as follows:(1)A three-dimensional CFD model of gas-liquid flow in a tube-type microreactor was established.The results show that the gas-liquid in MTMCR exhibits three flow patterns:droplet flow,elongated-droplet flow and churn flow.When the Reynolds number of gas phase exceeds 154.2 and the gas-liquid ratio exceeds 11,the flow pattern exhibits droplet flow and elongated-droplet flow.(2)Based on the CFD simulation of gas-liquid flow in the MTMCR,the 3D CFD model of water absorption CO2 mass transfer in MTMCR was established by adding component conservation equations and UDF to compile mass flux source terms.The results show that the error between the simulated values of CO2 saturation and the experimental results in published literature is in the range of±10%.With the increase of gas flow rate,the liquid mass transfer coefficient,volumetric mass transfer coefficient,and CO2 saturation rate increase.As the liquid flow rate increases,the mass transfer coefficient and volumetric mass transfer coefficient of the liquid increase,and the saturation rate of CO2 decreases.(3)A three-dimensional CFD model for the gas and gas-liquid phase of RPB was established.The results show that the wall rotation is closer to the real rotation of rotor than the zone rotation.The error of pressure drop between the RPB simulation value and the experimental result is within±10%.With the increase of gas flow rate,the pressure drop gradually increases,and the turbulent kinetic energy of the inner and outer cavities increases slightly.With the increase of the rotational speed,the pressure drop of the inner and outer cavities increases slightly,and the turbulent energy in the rotor area increases.The pressure drop of wet bed is higher than that of dry bed under the same gas flow rate and rotating speed.