The Research On Internal And External Characteristics Of Triplex Double-function Oil-gas Multiphase Pump

Multiphase pump is the core equipment during the transportation of oil-gas medium.Because the pump should convey gas-liquid two-phase medium which is in complicated conditions,so it is very diffcult to design and it has become one of the research hotspots in the pump industry at home and abroad.A kind of reciprocating multiphase pump that can run in the condition of high gas rate with high discharge pressure and high efficiency has been proposed during recent years in china.The inlet vales and the outlet valves considering its discharge process were researched,but few researches were done on the flow characteristics of the pump.However,the suction process has a great influence on the discharge process,and there is much interrelationship between the motion characteristics of the valve and the performance of the pump.In addition,the input power of reciprocating pump was deduced in some documents for compressible medium,its applicability was not identified yet.The research on the triplex double-function oil-gas multiphase pump 3DP90-70/3.0 was carried out in this thesis.The working process of the pump and its valve was analyzed theoretically at first,and then the 3D dynamic simulation for the multiphase pump of one chamber together with its valve was conducted in a stroke using FUENT,in different oil-gas condition.The effect of suction pressure,discharge pressure and gas rate on the pump valves,the flow characteristics,the input power was analyzed.In this paper,the main work and results are as follows:1.The velocity curve of the valve plate and lift curve were obtained by dynamic simulation with the program of UDF using FUENT.The delayed angle of the valve plate in opening process and close process were researched,and the impact velocity of valve plate against the lift limiter and the valve seat were analyzed.2.The instantaneous flow rate of the multiphase pump was obtained by superimposing the instantaneous flow rate of every chamber.The average flow rate and the flow pulsation were analyzed.The results show the average suction flow rate increased with the increase of the suction pressure and decreased with the increase of the gas rate,it almost could not be influenced by discharge pressure.The flow pulsation of discharge flow rate is mostly much greater than that of suction flow rate,it increased largely with the increase of the discharge pressure and the gas rate,while it decreased with the increase of the suction pressure.3.The average pressure on the piston head was obtained by analyzing the dynamic simulation of the working process of one chamber.The input power of the multiphase pump was calculated by drawing P-V indicator diagram using the pressure above,it was also theoretically calculated.The results show that the simulated input power is closer to the actual input power than the theoretical input power,the simulated input power increased with the increase of suction pressure and discharge pressure,while it decreased with the increase of the gas rate.