Objective The domestic oilfield-associated gas ethane recovery adopts liquid subcooled process(LSP);the aim of this study is to solve the problems of higher energy consumption and lower recovery rate in the actual operation condition of LSP.Methods Based on the LSP and the principles of gas-phase subcooling and gas-liquid two phases mixed subcooling,two improved processes,gas and liquid subcooled process(GLSP)and feed gas split subcooled process(FGSP),were proposed and analyzed in comparison with each other,focusing on the characteristics and adaptability to CO2 in the raw gas.Results Firstly,the GLSP is suitable for the ethane recovery process of oilfield-associated gas with low outgoing gas pressure.It is characterized by high ethane recovery rate and strong adaptability to CO2(CO2 mole fraction of 0.5％-2.5％).Secondly,the optimal pressurization pressure range of the GLSP is 4.0-4.5 MPa,and the ethane recovery rate should not exceed 95％.Thirdly,under the same condition of the CO2 content of raw gas,as the gas becomes richer,the ability of the demethanization tower to control CO2 freezing and blocking is increasing.Fourthly,under the same gas conditions,the total energy consumption of the plant increases with the increase of CO2 content in the feed gas.Conclusions The proposed improved process has increased the recovery rate of ethane,determined the optimal pressurization range,and improved the adaptability to CO2 in the raw gas,providing a reference for the design of actual low-pressure rich gas ethane recovery devices.
low pressure rich gasethane recoveryrecovery rateprocess improvementCO2 freezing and blocking
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