Research On Wear Of Pipeline System Of Solid-liquid Two-phase Centrifugal Pump

The centrifugal pump pipeline systems have the advantages of simple structure,small size,stable flow,and excellent performance.Therefore,it has become the preferred power supply equipment in the seabed mining process.However in the process of medium transportation,the wear on the flow wall cannot be avoided.In this paper,a single-stage single-suction solid-liquid two-phase centrifugal pump was experimentally studied and numerically simulated.Mainly used the CFD(Fluent)-DEM(EDEM)method and also took into account the non-negligible particle-particle,particle-wall interaction in the flow of large particles.In the experiment,the paint coating method was used to observe the wear position and the ultrasonic thickness measurement method was used to measure the wall thickness loss.The performance of the centrifugal pump was measured at different particle mass concentrations(Cm=1%-Cm=10%),particle diameter was 3 mm and mass flow rate was 70m3/h.The main findings are as follows:(1)The performance of centrifugal pump will be affected by the flow medium properties.When the particle concentration increases,the head and efficiency of centrifugal pump decrease obviously,but the shaft power will change slowly,it’s presented increase and later decrease trend.Because of the high density and poor fluidity of particles,it needs more energy to transport particles.At the same time,particles affect the flow field distribution in the centrifugal pump,which increases the size and number of vortices in some areas of the pump,resulting in the overall performance of the pump.(2)The wear in centrifugal pump blade working surface and the volute 6-7 section is most severely,and the thickness loss rate of impeller,volute and wear plate in centrifugal pump changes periodically with impeller rotation.When the blade rotates to the top of the volute 5-6 section,the thickness loss rate of the blade is the largest.Volute wear is related to particle movement and wall position.The wall wear rate increasingly with the particle concentration,but its expansion trend gradually decreases accordingly.This is because the particles adhere to the inner wall of the volute to form a particle buffer layer.The increase in concentration does not linearly increase the effect of the particles on the wall surface.(3)The relationship between the maximum wear on the cross section of straight pipe and pipe length,particle distribution and wall wear are analyzed.The results show that when the particles flow steadily for a period of time,the wear of the wall of the straight pipe decreases gradually along the length of the pipe,and the wear of the horizontal pipe is more serious than that of the vertical pipe due to the effect of gravity.The outer arch of the elbow is the most severely worn area,the closer it is to the elbow outlet,the more severely worn.(4)The average velocity of particles at different concentrations is extracted.It is found that there is a velocity difference between the particles and the fluid,and the two-phase medium will accelerate in the centrifugal pump.However,due to inertia,the acceleration time of particles is longer,and it still accelerates for a while even it flow out of the centrifugal pump.Inside of the pipe,the particle distribution changes greatly,and the particle velocity will change dramatically when the structure is different.The variation of particle flow process provides strong evidence for the analysis of wall wear of flow passage components.