NOVELTY - Separation (M1) of gas stream containing methane and ethane, ethylene, propane, propylene, and heavier components into a volatile gas fraction involves removing at least a portion of residue gas stream as a residue gas reflux stream and cooling, condensing, and then supplying the residue gas reflux stream to the demethanizer as a demethanizer reflux stream.    USE - For the separation of a gas stream containing methane and ethane, ethylene, propane, propylene, and heavier components into a volatile gas fraction containing a substantial amount of the methane and lighter components and a less volatile fraction containing a large portion of ethane, ethylene, propane, propylene, and heavier components (claimed).    ADVANTAGE - The novel methods decrease the compression requirements for residue gas while maintaining a high recovery yield of ethane components from a hydrocarbon gas stream. They are simplified, to minimize capital costs associated with additional equipment.    DETAILED DESCRIPTION - Separation (M1) of gas stream containing methane and ethane, ethylene, propane, propylene, and heavier components into a volatile gas fraction containing a substantial amount of the methane and lighter components and a less volatile fraction containing a large portion of ethane, ethylene, propane, propylene, and heavier components involves:    (1) cooling and at least partially condensing a hydrocarbon feed stream;    (2) supplying the hydrocarbon feed stream to a cold separator;    (3) separating the hydrocarbon feed stream into a first vapor stream and a first liquid stream;    (4) splitting the first vapor stream into a first separator overhead stream and a second separator overhead stream;    (5) expanding the first separator overhead stream to produce an expanded first separator overhead stream, and then supplying a demethanizer with the first liquid stream as a first tower feed stream and the expanded first separator overhead stream as a second tower feed stream;    (6) cooling and at least partially condensing the second separator overhead stream, and then supplying a reflux separator with the second separator overhead stream;    (7) separating the second separator overhead stream into a reflux separator overhead stream and a reflux separator bottoms stream;    (8) supplying the demethanizer with the reflux separator bottoms stream as a third tower feed stream;    (9) cooling, substantially condensing, and then supplying the demethanizer with the reflux separator overhead stream as a fourth tower feed stream. The demethanizer produces a demethanizer overhead stream containing a substantial amount of the methane and lighter components and a demethanizer bottoms stream containing a major portion of recovered ethane, ethylene, propane, propylene, and heavier components;    (10) warming and compressing the demethanizer overhead stream to produce a residue gas stream; and    (11) removing at least a portion of the residue gas stream as a residue gas reflux stream and cooling, substantially condensing, and then supplying the residue gas reflux stream to the demethanizer as a demethanizer reflux stream.