Research On The Design And Wear Of A Ceramic Centrifugal Slurry Pump

Ceramic pumps have been widely used in industries like chemical engineering,meltallurgy,mining,environmental protection and so forth because of the high resistance to abrasion,erosion and high temperature.As the substitute for alloy pumps and nonmetal pumps,the use of ceramic pumps can save massive metal resource,prolong the service life of flow components and increase enterprise efficiency.In this dissertation,a systematic and easily-operated desigh method of ceramic centrifugal slurry pump has been presented based on the summary of the design method for centrifugal slurry pumps that put forward at home and abroad,.Then numerical calculation has been conducted to investigate the influence of blade thickness,volute form and flow area of the annular volute on the unsteady flow in a ceramic centrifugal slurry pump.Meanwhile,the effect of blade thickness on the wear of impeller has been analyzed by the combination of numerical calculation and wear test.The main research contents and creative achivements of this dissertation are summarized as follows.(1)Firstly,the current research and the development history of ceramic pumps have been introduced.Then the research survey of domestic and foreign experiments on slurry pumps has been conducted comprehensively and the movement of solid particle in slurry pumps and the application scope of head drop equation have been summarized systematically.Thirdly,the literature aimed at the solid-liquid two-phase flow in slurry pumps has been introduced and the merits and demerits of several calculation models have been compared.Finally,the resent research of wear mechanism in slurry pumps at home and abroad has been presented and the wear pattern of flow components of slurry pumps has been discussed.(2)By combining the advantages of solid-liquid two-phase flow design method and the traditional empirical parameter design method,a systematic and easily-operated design method of ceramic centrifugal slurry pump has been presented.The influence of the selection of some key parameters on the pump hydraulic performance and the wear pattern of flow components has been discussed in detail.The selection criteria of inlet blade height,blade inlet angle,blade outlet angle and balde wrap angle for the impeller with thick blades has been put forward.(3)Transient numerical calculation has been conducted to investigate the influence of blade thickness on the unsteady flow in a ceramic centrifugal slurry pump with an annular volute.Two impellers with different blade thickness has been trail-manufacured for hydraulic performance experiment,and the experimental results show a good agreement with the numerical results.The time-averaged relative flow angle has been put forward for the first time with the advantage in observing the flow separation and secondary flow in the impeller.The results show that the increase in blade thickness will alleviate the diffusion of the impeller passage resulting in an increase in pressure pulsation at the impeller inlet but a decrease in pressure pulsation at the blade pressure sides near impeller exit.Meanwhile,when the blade thickness increases the radial force and axial force on the impeller decreases which will reduce the vibration of pump so that a more stable operation of pump has been achieved.In addition,the head drop at large flow rate increases and the best efficienty point offsets towards the low flow rate condition when the blade thickness increases.(4)Transient numerical calculation has been conducted to investigate the influence of flow area of the annular volute on the unsteady flow in a ceramic centrifugal slurry pump.Two annular volutes with different flow area have been trail-manufactured to testify the accuracy of numerical results.The results show that when the flow area of annular volute increases the hydraulic performance at the rated flow decreases slightly but increases obviously at large flow condition with a broader high efficiency region.Meanwhile,the pressure pulsation intensity decreases,the radial force on the impeller reduces and with a more uniform circumferential distribution when the flow area of the annular volute increases.The increase in the flow area of the annular volute can decrease the pump vibration and improve the operation stability.(5)Five volutes,namely a spiral volute case,an annular volute case,a quasi-annular volute case and two quasi-spiral volute cases,have been designed to investigate the volute form on the unsteady flow in a ceramic centrifugal slurry pump by conducting the transient numerical calculation for the first time.The results show that the hydraulic performance ranks from high to low as follows: spiral volute case,two quasi-spiral volute cases,quasi-annular volute case and annular volute case.The hydraulic performance of quasi-annular volute is better than annular volute at large flow rate condition but worse at low flow rate condition.The annular volute case has the smallest pressure pulsation intensity while the pressure pulsation intensity in the spiral volute case is the largest.(6)Particle model which is a solid-liquid two-phase flow has been utilized to investigate the influence of blade thickness on the wear of impeller of a ceramic centrifugal slurry pump for the first time.The distribution of fraction and the stream of relative velocity of solid particle have been presented to predict the wear pattern of impeller.Two impellers with different blade thickness have been trail-manufactured to conduct a wear test to testify the numerical results and a good agreement between experimental and numerical results has been achieved.The results show that when the blade thickness increases the suction sides of impeller blades have been worn more severe,but the pressure sides are with less abrasion,especially the region near impeller exit.The area with severe abrasion on the surface of impeller shroud increases,and the abrasion develops towards the blade suction sides.The top surface of impeller blades near impeller inlet has been worn more severe but there is less abrasion at the top surface of impeller blades near impeller exit with the increase in blade thickness.No obvious abrasion could be found in the ceramic annular volute.Only some washing trace by solid particles could be observed near the ? cross-section and the volute tongue which indicates that the wear resistance of engineering ceramic is much better than engineering plastic.