Research On Solid-liquid Two-phase Flow Of Axial Flow Pump In Polypropylene Loop Reactor

Axial flow pump in polypropylene loop reactor is the core circulating driving device of polypropylene synthesis process in Spheripol loop reactor.It plays a very important role in the whole synthesis process.There are unstable phenomena such as fluctuation of axial power in the actual operation process.Therefore,it is of great significance to study the internal flow law of the axial flow pump for the safe and stable operation of this pump.In this paper,the solid-liquid two-phase flow of the pump is systematically studied combining theoretical analysis,test and numerical calculation.The main work and innovative results are listed as follows:1.For the first time,the numerical calculation method of solid-liquid two-phase flow in loop reactor was applied to the internal flow analysis of axial flow pump,and the reliability of the numerical calculation results was verified by the external characteristic curve of pump performance test.2.By comparing the numerical results of different turbulence models,the suitable turbulence model of SST model is determined,and based on this,the three-dimensional steady calculation of the whole flow field is carried out.According to the calculation results,the eddy viscosity coefficient and turbulent kinetic energy of single-phase propylene are less than that of single-phase clear water,and its head value and efficiency value are larger than that of single-phase clear water.With the increase of solid particle diameter,the head value of the pump fluctuates less than 3%,and the efficiency value fluctuates less than 0.3%.With the increase of solid volume fraction,the head value and efficiency value of the pump decrease obviously.3.Pressure fluctuation analysis by calculating unsteady value shows that the pump pressure fluctuation is obvious,which is one of the factors affecting the fluctuation of the axial power of the annular pipe axial flow pump.The determination of the increase and fluctuation of solid volume fraction is also one of the factors.Through the head performance curves of different solid volume fraction and different pump speed,the modified curves of regulating pump speed under different volume fraction are obtained.