Abstract: In the recovery of C.sub.3+ hydrocarbons from a feed stream containing hydrogen and C.sub.1 to at least C.sub.5 hydrocarbons, e.g., a refinery waste gas, comprising cooling and partially condensing the feed stream; separating the partially condensed feed stream into a liquid fraction and a gaseous fraction; expanding the gaseous fraction, and fractionating the liquid fraction in a rectification column to obtain product stream consisting essentially of C.sub.3+ hydrocarbons and a residual gas stream product containing predominantly C.sub.2- hydrocarbons, one improvement comprises passing (a) the gaseous fraction prior to expansion; (b) the liquid fraction prior to rectification; and (c) the gaseous fraction after expansion, in indirect heat exchanger relationship with the feed stream to be cooled. Other improvements comprise separate removal of C.sub.1 and C.sub.2 fractions from the hydrogen gas; the use of a C.sub.

Abstract: In a process for the separation of at least carbon dioxide and hydrogen sulfide from a raw gaseous mixture to form a purified gaseous mixture comprising passing said gas through a sour gas removal system including the steps of scrubbing said gaseous mixture with a liquid scrubbing agent having a higher affinity for hydrogen sulfide than for carbon dioxide, removing from said system an off-gas enriched in hydrogen sulfide, and passing said off-gas to a sulfur recovery system comprising the conversion of sulfur values to elemental sulfur and the recovery of a tail gas containing hydrogen sulfide and sulfur dioxide,the improvement which comprises hydrogenating said tail gas to convert sulfur dioxide to hydrogen sulfide and recycling resultant hydrogenated tail gas to said sour gas removal system, whereby essentially no hydrogen sulfide or sulfur dioxide is discharged into the environment.