Study On Vibration Mechanism Of Liquefied Natural Gas Reciprocating Pressurized Piston Pump Group And Vibration Reduction Of Connecting Pipeline

With the development of Gas industry at home and abroad,Liquefied Natural Gas,LNG(Liquefied Natural Gas,or LNG)and Compressed Natural Gas CNG(Compressed Natural Gas,CNG)LPG stations technology gradually become the main energy in the field of domestic transportation station,based on the two types of yard,The development of L-CNG(liquefied natural gas to compressed natural gas filling station)and HCNG(mixed hydrogen gas)filling station,the LNG reciprocating pressurized piston pump group plays an important role in the whole system of power equipment of L-CNG filling station.For the special low temperature working condition,the relative moving parts such as the moving ring and static ring of the shaft seal,the plunger and cylinder liner of the piston pump,etc.,are required to be made of materials with similar linear expansion coefficient,and the linear expansion coefficient of the parts must be less than or equal to the linear expansion coefficient of the enveloped parts,in order to prevent the phenomenon of sticking during cold contraction.Especially for those coupling requirements are very strict motion parts in the last finishing,must be cryogenic treatment,cryogenic temperature should be equal to or below the operating temperature,processing time is 1-4 hours.In view of this and its strict and unique process requirements,rotary piston pump is difficult to achieve,for this reason,most of the current gas station using reciprocating piston pump.But LNG reciprocating plunger pump group compared with other pump,vibration and noise is serious,the other group with LNG reciprocating plunger pump connecting pipe is pressure pipeline vibration,the L-CNG stations to process in the operation of the system pressure gauge,pressure and temperature sensors failure safety attachment,the potential damage of pipeline safety accident risk is huge.Booster based on LNG reciprocating plunger pumps and piping as the research object,from the pump fluid vibration to the mechanical vibration,from the input power end components modal analysis to the output end connection pipe of fluid-solid coupling model is established in this paper,from the pipe vibration research to pipeline pipe clamp and the piping system vibration effectively,reasonable equipped with vibration absorber which is used to comprehensive research and analysis of LNG reciprocating plunger pump to pressurize group and output pipe vibration mechanism and how to avoid resonance,the effective method to reduce vibration and noise.It will provide some theoretical support for further research on vibration reduction of LNG reciprocating pressurized piston pumps and connecting pipelines,and provide some guidance for enterprises to build safe and reliable LNG field stations.This paper first introduces the working principle of L-CNG filling station,and points out some problems caused by vibration of LNG reciprocating pressurized piston pump and pipeline during operation.The research and development of low temperature reciprocating pressure piston pump,machine body,crankshaft system and infusion pipeline system at home and abroad are briefly introduced.Secondly,the influence of flow pulsation and cavitation on the vibration of LNG reciprocating pressurized piston pump group and connecting pipeline and the influence of fluid characteristics on the natural frequency of the pipeline are theoretically studied and analyzed.The relationship between the fluid forces in the piston chamber,the forces on the crank connecting rod mechanism and the crank Angle is studied,and the forces exerted on the crankshaft and transmitted to the bearing through the crankshaft are theoretically studied,as well as the influence of the pressure of high-pressure fluid in the piston cylinder and the reciprocating inertia force on the vibration of the crankshaft system.Based on the model elements of AMESim machinery,fluid and control,the simulation model of LNG reciprocating pressurized piston pump group was built.The flow rate and pressure variation rules of the two-cylinder single-acting piston pump and the opening and closing characteristics of the suction and discharge valves were studied through the simulation,and the fluid vibration characteristics were studied.Based on the modal analysis theory,the booster LNG reciprocating plunger pump power on the crankshaft,connecting rod,and the body finite element analysis model is established,using ANSYS software calculation analysis of the crankshaft,connecting rod,and the body under the constraint condition of ten order natural frequency and modal vibration mode,analysis of dynamic characteristics of crankshaft,connecting rod,and the body and the weak link,LNG reciprocating plunger pump to pressurize group in the future to provide certain theoretical guidance for the optimization design of the ontology.Finally,based on the relationship between the vibration of LNG reciprocating pressurized piston pump group and the vibration of connecting pipeline,the vibration characteristics of connecting pipeline and the vibration reduction technology of pipeline are studied,which can be used for reference in the subsequent design and construction of the optimal LNG site process system.