Research On Ethane Recovery Technology In CQ Gas Field

In recent years,major domestic oil and gas fields have continuously emphasized increasing production,improving efficiency,and increasing resources.And natural gas advanced treatment projects with good economic returns and high recovery value are gradually put on the agenda.In order to increase economic efficiency and meet market demand,CQ Gas Field is planning to build a large-scale ethane recovery plant for the recovery of ethane in natural gas.Due to the large depth of cooling in the ethane recovery process and the icing of the device,strict requirements are imposed on the adaptability and safety of the process.Therefore,it is of great significance to carry out research on ethane recovery process technology,increase the recovery rate of light hydrocarbon resources,and reduce the overall energy consumption of the plant,in order to achieve high-efficiency,economical,and safe gas field development in China.This article investigates the status quo of ethane recovery technology at home and abroad.Combined with the temperamental conditions of raw gas in CQ gas field,the advantages and disadvantages of representative processes such as GSP,LSP,RSV,and SRC were analyzed,and the advantages of RSV process in ethane recovery and temperament suitability were discovered.In order to further improve the recovery rate of ethane in view of the insufficiency of the conventional RSV process in the control of CO2 freezing,it is determined that the RSV process will be improved.In this paper,based on the research of the ethane recovery process mechanism and the control of the CO2 frozen plugging technology,it is determined that the use of multi-stage separation,multi-level cooling and multiple strands of reflux to improve the top of the demethanizer reflux,and proposed a demethanizer separation process improvement program.Based on the CGCC and sensitivity analysis,the tower operation process is optimized,and the sideline reboiler and heat pump are set to optimize the thermal integration of the demethanizer tower,thereby further improving the ethane recovery rate and reducing the heat load of the demethanizer tower.In order to reduce the ethane recovery system's demand for utility projects,a study was conducted on the heat transfer network of the improved multi-stream cold box.Based on the pinch theory,the problems in the preliminary design of the heat exchanger network are identified,and the optimization direction of the heat exchanger network is clarified.Under the circumstance that the recovery rate of ethane products is kept unchanged,the amount of cold and heat utility projects after the optimization of the heat exchange network has significantly decreased,and the overall energy consumption of the main unit is reduced by 21.57%,thereby achieving the goal of energy saving and consumption reduction.Based on the research of RSV ethane recovery process,CO2 frozen plugging control technology,demethanizer simulation optimization technology and system thermal integration technology,the overall process plan of CQ gas field natural gas processing unit was proposed.The CQ gas field improved the utilization efficiency of the cooling capacity by adopting an improved process scheme,the ethane recovery rate reached 95.98%,and the integrated system energy consumption was reduced by 115159×104 MJ/a compared to the RSV process,and the energy saving effect was significant.In addition,after studying the improvement of process adaptability,it was found that the process has good adaptability to condensate gas and associated gas,and it has good adaptability to different content of CO2 intake conditions.