Investigation Of Working Characteristics And Gas Pulsation Of Large Reciprocating Compressor

As the core equipment of fluid compression and transportation in petroleum,chemical and other fields,large Reciprocating compressor are widely used.The stable and safe operation of compressor is directly related to the economic benefit of production and the safety of personnel.The working characteristics of the compressor,especially the working characteristics of the gas valve,and the gas pulsation in the pipeline are very important for the stable operation of the compressor.Therefore,in this paper,the working characteristics of the compressor and the flow pulsation in the pipeline are studied as follows:(1)the working process of the compressor is analyzed,and the mathematical models of the compressor cylinder,valve,valve chamber and pipeline are established according to the changes of the thermodynamic parameters of the suction,compression,exhaust and expansion processes,mathematical model of each stage of reciprocating compressor is obtained,that is,the compressor working process simulation model.(2)Matlab software programming and runge-kutta method are used to solve the mathematical model of the working process of the compressor according to the analysis procedure of the working process of the compressor.the change law of cylinder pressure,the movement law of the exhaust valve slice,The change law of pressure and density of valve chamber and the change law of mass flow rate of the exhausting pipe are calculated.Compared with the simulation results with ignoring the influence of the gas pulsation in the valve chamber,the influence of the gas pulsation in the valve chamber is analyzed.The effects of different valve spring stiffness coefficient,valve plate lift,spring pre-compression and compressor speed on the working characteristics of the compressor are analyzed.(3)Based on the plane wave theory,the transfer matrix and stiffness matrix of basic components of pipeline are deduced,and the total transfer matrix and stiffness matrix of complex pipeline system are established.According to the boundary condition of the pipeline,the natural frequency of the pipeline gas column is calculated by using MATLAB programming.Compared with the measured values in the literature,the errors are less than 8%,which verifies the correctness of the calculation model.(4)The gas pulsation in the pipeline of a large natural gas reciprocating compressor is analyzed.The natural frequency of the gas column in the pipeline system is calculated according to the acoustic boundary conditions.There is no resonance.The pressure pulsation in the pipeline system is calculated by using the mass flow curve obtained from the simulation of the working process of the reciprocating compressor considering the pulsation of valve chamber,the pipeline system needs to be improved according to API 618.and the pipeline is improved according to the calculation of gas pulsation theory and engineering requirements,After the improvement,the gas pulsation of pipeline system is controlled within the standard.Taking a reciprocating compressor buffer tank of an offshore platform as a prototype,CFD simulation technology is applied to simulate the buffer tank,and the influence of some structural parameters on the working of the buffer tank is analyzed.