Study On Hydraulic Performance Optimization And Pressure Fluctuation Of Axial Flow Pump In Polypropylene Loop Reactor

Axial flow pump in Polypropylene loop reactor is a special axial flow pump,it is used in a loop reactor to provide power for it,it has the advantages of large flow rate,uniform material and temperature,and avoiding the precipitation of polymers.It is different from the traditional axial flow pump,the guide vanes are all welded by forgings,so it can not install twisted guide blades according to the conventional axial flow pump,because of the particularity of its structure and its complicated internal flow,resulting in the problems of power fluctuation,noise and unstable operation in its operation process,it is found that hydraulic performance and pressure fluctuation characteristics of axial flow pump in loop reactor are the main factors that affect its operation stability.Therefore,in order to optimize the internal structure and improve the stability of the axial flow pump in loop reactor,in this paper,the numerical simulation and experimental method are applied to carry out the research on hydraulic performance optimization and pressure fluctuation of axial flow pump in loop reactor,which plays an important role in improving the design level of the axial flow pump.In this paper,the axial flow pump in loop reactor with different straight guide vane is designed,and the simulation model is established,the CFD method is applied to the numerical calculation of the model,and the simulation results are compared with the experimental data;this paper analyzed the internal flow characteristics of axial flow pump in loop reactor at different parts,aiming at three factors,such as the thickness and length of the straight guide vane blade and the distance to the impeller,the influence of the straight guide vane structure on the hydraulic performance of the axial flow pump in loop reactor is studied by means of orthogonal design,taking head and efficiency as evaluation indexes,the optimal straight guide vane structure is obtained,which provides reference for the design of the straight guide vane structure,and analyzes the difference between the optimized model and the original model,the power fluctuation phenomenon of the axial flow pump in loop reactor is analyzed according to the monitoring of unsteady head characteristics of the axial flow pump in loop reactor.Based on the above research,this paper draws the following conclusions:(1)The numerical calculation in this paper is in good agreement with the experimental results,and the error of the two in the design condition is 0.28%,and it is within theallowable range of the engineering error,the simulation model in this paper is reliable;(2)the optimal size of straight guide vane is the 149 mm of length,38 mm of thickness,56 mm of the distance from the straight guide vane to the impeller;(3)compared with the original model,the optimization model has an increase in head and efficiency,it increased by 1.50% and 1.51% respectively under the rated condition,and the velocity,pressure and turbulent kinetic energy distribution of straight guide vane are more reasonable,the optimized straight guide vane structure is more suitable for the flow of the straight guide vane;(4)in the outlet of the impeller and the position of the straight guide vane presents the characteristic of four period sine,the amplitude of pressure pulsation reaches the maximum in the inlet of the straight guide vane;the pressure fluctuation amplitude at the main frequency of the optimization model compared to the original model at the hub in the cross section and outlet is lower;pressure fluctuation of the optimization model is more sinusoidal;the optimization model improves the structure of the straight guide vane,making the power fluctuation more regular and reducing the peak of the second frequency.