Abstract: A natural gas processing plant with a capacity of 6×106m3/d plans to adopt the recycle split-vapor （RSV） process to recover liquefied ethane. CO2 freezing and plugging in the demethane tower is a key technical bottleneck affecting the stable operation. With the goal of improving the ethane yield， according to the selection of liquefied ethane process for natural gas production and the formation mechanism of CO2 freeze blockage， the CO2 distribution and temperature of each tower plate of each tower plate under different CO2 contents were simulated. Through the simulation curve comparison analysis， the conclusion was concluded that when the CO2 content of the raw gas in the cold box was less than 5×10-5， the demethanizer would not freeze blockage. According to the analysis of different decarbonization processes， the alcohol amine method is selected to remove CO2 to meet the process requirements. The research results show that by using PZ+MDEA solution to remove CO2 from raw natural gas， the problem of freezing and blocking of CO2 in the deep cold zone between -90℃ and -105℃ can be effectively solved， and the ethane yield can reach more than 95%.

Key words: RSV process, liquefied ethane, demethanizer, CO2 freezing and plugging, amine solvent