Research On Co-simulation And Optimization Of Multiple Systems For Stepless Capacity Regulation Of Reciprocating Compressor

China is a country with energy shortage.How to achieve energy saving and emission reduction is always an important issue repeatedly emphasized in national planning.From the energy saving and emission reduction policy of the13 th Five-Year Plan to the carbon peak requirement of the 14 th Five-Year Plan,we can see that China attaches great importance to energy issues.Reciprocating compressor is widely used in petrochemical,natural gas transmission and metallurgical and chemical industries due to its wide range of adaptations and high compression efficiency.And its energy consumption accounts for a large proportion of industrial energy consumption in China,so compressor is one of the key equipment that enterprises need to save energy and reduce consumption.The stepless capacity regulation system of reciprocating compressor based on partial stroke top-open intake valve solves the problem of a large amount of energy waste caused by the inability of the compressor to adapt the flow regulation due to the fixed cylinder.At the same time,the system is widely used in industrial fields due to its wide adjustment range and good energy-saving effect.Because of the regulation and control performance requirements of the air quantity regulation system,the system actuator is required to move quickly within the range of travel and maintain at the limit for a certain time,which causes problems such as high speed impact of mechanical components,high vibration and noise,short life,fast wear and tear of hydraulic seals,etc.At the same time,the action characteristics of the actuator involve many subsystem parameters,which are directly related to the control system and compressor performance.Therefore,it is of great significance and value to optimize the structure of actuator and parameter matching of subsystem for improving the economy,performance-price ratio and operation ability of stepless capacity regulation system,which is safe,reliable,efficient and energy-saving.Aiming at the problems of high vibration impact,high noise and short service life of actuator,the stepless air quantity regulation system of reciprocating compressor was studied in the past.This paper carried out the research on optimum matching of key parameters of hydraulic system and mechanical system as well as optimum buffer modification of hydraulic components of actuator.Valve failure is a typical frequent failure of compressor.This paper explores the variation rule of compressor performance after coupling valve failure with air flow regulation.The research results in this paper play an important role in prolonging the service life of the actuator of stepless gas flow regulation system,improving the economic performance of the system and enhancing the safety and reliability of the system.Specific research contents are as follows:Firstly,according to the working principle of partial stroke pressure-open suction valve,various subsystem models of stepless capacity regulation system of reciprocating compressor are established,including working cycle model of reciprocating compressor under variable load,working model of mechanical system,hydraulic system and control system.Based on the mathematical model,the key parameters affecting system performance are determined.Through the analysis of coupling points of hydraulic system,mechanical system and reciprocating compressor system,a joint simulation scheme of steplesscapacity regulation system of reciprocating compressor based on interface technology is established.The validity of the model and the feasibility of the solution are verified by comparing the results of dynamic pressure data of simulation and experiment.Secondly,in order to reduce the ejection and withdrawal impact of unloader,prolong the service life of capacity regulation system and improve the safety and stability of system operation,an optimum buffer structure of hydraulic components of actuator with bi-directional buffer is put forward.Based on the cushioning principle and structure design,the kinematic model and simulation model of the cushioning piston and piston are built.The cushioning effect of the cushioning structure and the influence of key parameters on the cushioning performance are verified by simulation and experimental research,and the reliability of the cushioning structure is verified in a long period.Thirdly,based on the independent analysis results of key parameters affecting the unloader withdrawal action characteristics,the preliminary selection scheme is defined and the preliminary selection range of parameters is given.The coupling relationship between key parameters influencing unloader action characteristics is explored by simulation test,and the proxy mathematical model between key parameters(inlet pressure,return pressure and reset spring stiffness)and objective function(unloader ejection and withdrawal speed,system indicator power deviation and displacement deviation)is established.Aiming at the characteristics of multi-load condition and multi-objective mutual restraint of the capacity regulating system,a key parameter optimization method combining simulation test with multi-objective optimization method is put forward.The optimum results of the full load condition are determined by determining the inlet pressure,return pressure and reset spring rigidity.The optimization results are verified by experiments.After optimization,the effective value of the impact of the unloader is significantly reduced,the effective value of the ejection impact is reduced by about 20%,the effective value of the withdrawal impact is reduced by about 50%,and the gas regulation deviation is within 10%,which realizes the same time to ensure the energy saving of the compressor,prolongs the service life of the actuator,and improves the economy of the capacity regulation system.Fourthly,by establishing the mass flow leakage model of suction valve and combining it with the working model of variable-load compressor,the reciprocating compressor working cycle model under the coupling condition of suction valve leakage fault and capacity regulation is established,and the variation rules of compressor performance and capacity control system performance under the coupling condition are explored.The leakage of the suction valve causes the abnormal change of the indicator diagram of the compressor,the decrease of the exhaust volume of the compressor,the increase of the indicated specific work,and the decline of the economic performance of the compressor.At the same time,the reduction of the load aggravates the deterioration of the performance of the compressor caused by the leakage fault.Based on the experimental bench of the stepless capacity regulation system of the reciprocating compressor,the relevant experiments are designed to verify the correctness of the theoretical analysis conclusion.It lays a theoretical foundation for gas valve fault identification under coupling conditions and system regulation parameter optimization under fault conditions.Finally,the multi-objective optimization method of capacity regulation system and the hydraulic cushion optimization structure of actuator are successfully applied to a petrochemical nitrogen compressor.After optimization,the unloader vibration of the compressor on-site decreases greatly and the impact noise decreases significantly.At the same time,the reasonable matching regulation effect of parameters of electric control system is good.After a month of continuous and stable operation,the cushioning component has a good cushioning effect,which further verifies its reliability.Therefore,the optimized stepless capacity regulation system of reciprocating compressor not only realizes high efficiency and energy saving of the compressor,but also improves the economy of the regulation system and the safety and reliability of the system.