A process for producing a purified methane stream comprising separating and cooling a pressurized feed mixed gas stream containing a methane component and one or more hydrocarbon components heavier that methane, wherein the latent energy of each individual, separated component is captured by the process to further cool the pressurized mixed gas stream, the process comprising the steps of:
- (a) cooling the mixed gas stream in a feed cooling heat exchange zone;
- (b) further cooling, condensing, and purifying the cooled mixed gas stream of step (a) to produce a cold methane vapor product and a hydrocarbon liquid enriched in one or more hydrocarbons heavier than methane;
- (c) separating the cold methane vapor product from the hydrocarbon liquid;
- and
- (d) vaporizing at least a portion of the hydrocarbon liquid of step (b) in the feed cooling heat exchange zone to provide by indirect heat exchange at least a portion of the refrigeration required to cool the mixed gas stream in the feed cooling heat exchange zone m step (a), and withdrawing a vaporized hydrocarbon product from the feed cooling heat exchange zone.