Abstract: Aiming at the problems existing in the recovery process of light hydrocarbons (C₂+ components) from saturated refinery dry gas, such as high residual C₂+ content in dry gas, low recovery rate of ethane and light hydrocarbons, and relatively high energy consumption, an efficient combined absorption (ECA) process for deep recovery of light hydrocarbons was developed. The process adopts the technical route of “three-stage absorption and multi-stage separation”. Through the optimal combination of propane, butane and toluene as well as sequential graded absorption, efficient capture of C₂+ components in saturated dry gas is realized. Process simulation results show that the ECA process can increase the recovery rate of ethane and light hydrocarbons to more than 98%, the mole fraction of C₂+ components in the treated dry gas is no more than 1.0%, and the unit comprehensive energy consumption is reduced by more than 17% compared with the traditional scheme. After the newly built industrial unit was put into operation, the recovery rates of ethane and C₂+ light hydrocarbons reached 98.85% and 98.23% respectively, and the mole fraction of C₂+ components in dry gas was no more than 1.0%, realizing the deep recovery and high-value utilization of C₂+ light hydrocarbons. The process has technical advantages of low absorbent circulation rate, high product purity and low energy consumption, with remarkable economic benefits and broad prospects for industrial popularization and application.

Key words: saturated dry gas, light hydrocarbon recovery, combined absorption, ethane-rich gas