Simulation Research And Optimization Of The Direct Liquefaction And Separation Technology For The Coal Mine Methane

According to the difference between coal mine methane and traditional natural gas in composition,this paper focuses on the methane recovery from coal mine methane using cryogenic liquefaction and separation technology.HYSYS is applied to calculate properties of working medium and simulate the liquefaction and separation process of coal mine methane while Genetic Algorithm is employed to optimize the involved processes.Improved Genetic Algorithm is proposed to adapt to the optimization characteristic of natural gas liquefaction process.Exergy analysis method is adopted to research the optimal operation conditions,determining the reasonableness of no compression before liquefaction and the reasonableness of throttling before into the rectifying tower process.In the research of liquefaction cycle,nitrogen-expansion liquefaction cycle and SMR liquefaction cycle is simulated and optimized,determining the reasonableness of using SMR liquefaction cycle which provides the demanded cold energy in liquefaction and separation phases.On the premise that the process of methane recovery is absolutely safe in all phases,max methane recovery is determined as the optimization objective for the process optimization of direct liquefaction and separation process.Novel direct liquefaction and separation process which combines the absorption refrigeration cycle was put forward to solve the problem that high energy consumption and methane no complete utilization lies in former process.Finally,according to the comprehensive comparison between deoxidized liquefaction separation processes and direct liquefaction separation processes,valuable suggestions in application were given.