Flow Field Simulation And Structure Study Of Jet Loop Reactor For The Yeast Culture Process

Aiming at the yeast culture process,most of the reactors used in the industry are bubble column and air-lift loop reactors.The disadvantage of this type of reactor is that the gas content is low and the circulation is small,which is difficult to meet the production requirements.Jet Loop Reactor(JLR)as an efficient multi-phase flow reactor can effectively increase the gas content and increase the liquid phase circulation in the reactor,which can promote the yeast culture process.At present,the research on JLR reactors in the literature is generally concentrated on the laboratory scale,and there is insufficient guidance for the development of large-scale reactors on an industrial scale.In order to solve the above problems,this topic adopts the method of Computational Fluid Dynamics(CFD)to simulate the industrial size JLR reactor and provide theoretical guidance for its application in the yeast culture process.The thesis compared the liquid single-phase injection and gas-liquid two-phase injection processes and found that with the participation of gas,the amount of circulating liquid in the reactor increased.Research on the influence of structural parameters on JLR performance found that reducing the nozzle diameter,increasing the nozzle position,and extending the length of the guide tube could increase the gas content in the reactor.When the ratio of the guide tube diameter to the reactor diameter was 0.6,JLR had the highest gas content rate.By reducing the nozzle diameter,increasing the nozzle position,and reducing the length of the guide tube,the circulating liquid volume could be effectively increased.When the ratio of the guide tube diameter to the reactor diameter was 0.7,the circulating liquid volume was the largest.Reducing the nozzle diameter could increase the overall turbulent dissipation rate of the reactor.Increasing the nozzle position could increase the volume of the injection zone,thereby increasing the turbulent dissipation rate in the guide tube and promoting the mass transfer of the gas-liquid two-phase.Based on the CFD simulation results,the empirical formulas of gas content and circulating fluid volume with the structural parameters of JLR were revised.The effects of the number of reactor nozzles,the shape of the deflector tube and the liquid outflow position on the reactor were studied,and suitable structural characteristics were given.The calculation results showed that the double nozzle structure could increase the circulating liquid volume,and the lifting effect increased with the increase of the apparent liquid velocity;the tapered guide tube could effectively reduce the flow resistance,increase the reactor circulating liquid volume,and weaken local vortex;the structure of the top liquid discharge also increased the amount of circulating liquid.Increasing the amount of circulating liquid would facilitate the mixing of the imported materials and the materials in the JLR.In order to enhance the expansion process of the yeast culture process,the jet loop reactor might consider the use of a double nozzle,tapered diversion tube structure,and the top liquid discharge method was used for the outlet.