Method for recovering a stream of C2+ hydrocarbons in a residual refinery gas and associated installation

Method for recovering a C2+ hydrocarbons stream in a residual refinery gas, comprising:

• forming a residual stream from the residual refinery gas;
• feeding the residual stream into a flash drum to form a gaseous overhead flow and a liquid bottom flow;
• feeding the liquid bottom flow into a distillation column via an inlet;
• cooling the gaseous overhead flow in a heat exchanger to form a cooled overhead flow;
• separating the cooled overhead flow into a liquid lower stream and into a gaseous top stream;
• feeding the liquid lower stream into the distillation column via an upper inlet positioned above the inlet for feeding the liquid bottom flow;
• recovering the C2+ hydrocarbons stream at a bottom of the distillation column;
• extracting a gaseous overhead stream at a head of the distillation column;
• forming at least one effluent stream from the gaseous overhead stream and/or from the gaseous top stream;
• heating the at least one effluent stream in a heat exchanger via heat exchange with the gaseous overhead flow;
• wherein separating the cooled overhead flow comprises feeding the cooled overhead flow into an absorber, and injecting a methane-rich stream into the absorber to place the cooled overhead flow in contact with the methane-rich stream, wherein the molar content of methane in the methane-rich stream is higher than 90 mole %.