Improvement and optimization of ethane recovery processes for medium and high pressure rich gas

Aiming at the problems of high energy consumption and low process heat integration in the RSV(recycle split-vapor) process in the ethane recovery of medium and high pressure rich gas, based on the principle of distillation, RSVF (recycle split vapor with liquid flashing) process is proposed by changing the gas source and using multi-stage separation. Then taking the ethane recovery rate and the total compression power consumption as the response values, and the demethanizer pressure, the cryogenic separator temperature, the reflux ratio of the external dry gas, and the flashing temperature are selected as the design variables through the sensitivity analysis method. Behnken's response surface method is optimized for the process parameters, and the two models are verified by ANOVA. The optimal process parameters obtained after optimization are as follows: the pressure of the demethanizer is 2 820 kPa, the temperature of the cryogenic separator is -48 ℃, the reflux ratio of the external dry gas is 14.2%, and the flashing temperature is -40.6 ℃. When the natural gas processing capacity is 5×10⁶ m³/d, the economic benefit of the process has increased by 15.51 million yuan per year.