Design And Performance Simulation Analysis Of Multi-stage Soft Plunger Pump

At present,many petroleum fields in China have applied ASP flooding technology,which often leads to the phenomenon of scaling and preventing the operation in conventional petroleum pumps.Moreover,the petroleum viscosity of ASP flooding wells is very high,which leads to the increase of plunger downstroke resistance and easily leads to rod bending.Soft plunger pump can be deal with by the ill effects of ASP flooding,but as a result of soft plunger pump plunger materials for non-metallic materials,easily damaged,affect the service life of petroleum well pump.ln view of the above problem,this paper designs a new kind of Multi-stage soft plunger pump,on the basis of the research on its performance,the structure is optimized.The structure of multi-stage soft plunger pump is designed.This kind of pump uses the hydraulic self-sealing soft plunger to replace the metal plunger of the conventional plunger pump.The biggest difference with the previous soft plunger pump is that it adopts the structure of multiple plunger in series to achieve the effect of grading pressure and sealing step by step.By comparison with the single-stage soft plunger pump,it can be seen that the maximum stress on the sealing cylinder of the two-stage soft plunger pump is about 50% less than that of the single-stage soft plunger pump.Therefore,the multi-stage soft plunger pump can extend its service life to some extent.Because the wear resistance of the soft plunger sealing cylinder is the key factor affecting the pump life,the friction and wear tests of polyether ether ketone(PEEK),polyurethane and nitrile rubber were carried out in this paper.The test results showed that the wear resistance of PEEK is far superior to other materials,so this paper chose polyether ether ketone as the sealing cylinder material.The influence of main parameters on the deformation and leakage of sealing cylinder of soft plunger pump is analyzed by using the fluid-solid coupling method.The results show that when other conditions are constant,the thicker the plunger sealing cylinder is,the smaller the deformation and the greater the leakage.The smaller the initial clearance,the greater the nonlinear degree of axial pressure distribution in the fluid domain,the larger the deformation and the smaller the leakage of the soft plunger sealing cylinder.The greater the pressure difference is,the greater the leakage quantity will be.As the deformation quantity of the sealing cylinder will also be larger,the speed of the increase of the leakage quantity will be reduced.The greater the pressure at the inlet and outlet,the smaller the deformation of the sealing cylinder and the greater the leakage.In order to make the partial pressure values of the plunger at each level of the multi-stage soft-plunger pump converge,an optimization method of plunger length is proposed in this paper,and takes the two-stage soft plunger pump as an example to optimize.The result shows that when the length of the first plunger is 50 mm,the length of the second plunger is 47.2 mm.