(US5287703-A)      Low temp. sepn. for recovering a heavy hydrocarbon prod. from a hydrocarbon contg. gas stream comprises (a) cooling the gas stream to effect partial condensn., (b) phase sepg. the partially condensed stream into its vapour and liq. components in a phase separator, (c) rectifying the vapour component by low temp. dephlegmation to produce a light gas stream and heavy liq. stream, and (d) stripping the liq. component from (b) and the heavy liq. stream from (c) in a stripping column contg. a reboiler. The bottoms stream from the stripping column is the heavy hydrocarbon prod. Refrigeration for the process is provided from a single loop vapour recompression refrigerator using a mixed refrigerant.    Sepn. efficiency is improved by (i) passing the liq. component from step (b) and the heavy liq. stream from step (c) directly to the stripping column, (ii) operating the stripping column at below ambient temp., (iii) passing the overhead vapour from the stripping column directly to the phase separator and (iv) using the mixed refrigerant as a heating medium for the reboiler of the stripping column.    Pref., the gas stream contains H2, N2, CO, CO2, CH4 and at least 2C hydrocarbons.    ADVANTAGE -   Energy efficiency is increased. The process requires only a compressor.    (JP94062955-B2)      Low temp. sepn. process comprises (a) cooling the gas stream to effect partial condensation; (b) phase sepg. the partially condensed gas stream into its vapour and liq. components in a phase separator; (c) rectifying the vapour component from (b) by low temp. dephlegmation to produce a light gas stream and a heavy liq. stream; (d) stripping the liq. component from (b) and the heavy liq. stream from (c) in a stripping column contg. a reboiler wherein the bottom stream from the stripping column is the heavy hydrocarbon prod.; and (e) providing the predominant amount of the refrigeration for the process from a single loop vapour recompression refrigerator employing a mixed refrigerant. The efficiency of the sepn. process is increased by (f) passing the liq. component from (b) and the heavy liq. stream from (c) directly to the stripping column of (d); (g) operating the column at below ambient temp.; (h) passing the overhead vapour from the column directly to the phase separator of (b) to be rectified with the vapour component of (b); and (i) using the mixed refrigerant as a heating medium for the reboiler of the stripping column in order to provide at least a portion of the heat duty for the reboiler.    USE/ADVANTAGE -   Process for the recovery of 2C or higher hydrocarbons from a hydrocarbon contg. stream using the sequential steps of cooling, phase sepg., rectifying and stripping wherein the refrigeration is derived predominantly from a single loop vapour recompression refrigerator employing a mixed refrigerant. Gas stream is processed at a lower pressure resulting in lower energy of sepn. and appts. is cheaper with single compressor.    (EP528320-B1)      In a low temperature separation process for the recovery of C2+ hydrocarbons or C3+ hydrocarbons from a hydrocarbon containing gas stream, comprising: (a) cooling the gas stream to effect the partial condensation thereof; (b) phase separating the partially condensed gas stream into its vapour and liquid components in a phase separator (3); (c) rectifying the vapour component from step (b) by low temperature dephlegmation to produce a light gas stream and a heavy liquid stream; and (d) stripping the liquid component from step (b) and the heavy liquid stream from step (c) in a stripping column (4) containing a reboiler (8), wherein the bottoms stream from the stripping column (4) is the heavy hydrocarbon product; (e) providing the predominant amount of the refrigeration for the process from a single loop vapour recompression refrigerator employing a mixed refrigerant; the improvement for increasing the efficiency of said separation process comprising: (i) passing the liquid component from step (b) and the heavy liquid stream from step (c) directly to the stripping column (4) of step (d); (ii) operating the stripping column (4) at below ambient temperature; (iii) passing the overhead vapour from the stripping column (4) directly to the phase separator (3) of step (b) to be rectified with the vapour component from step (b); and (iv) using the mixed refrigerant employed in step (e) as a heating medium for the reboiler (8) of the stripping column (4) in order to provide at least a portion of the heat duty for the reboiler (8).