Patent GB-831262-A (GB)
Title: Recovery and purification of acetylenes
Inventor: SCOFIELD RAYMOND CLOGSTON
IPC: C07C7/11
Filed: 1956-10-01
Abstract: <PICT:0831262/III/1> <PICT:0831262/III/2> Acetylenes are recovered from gas mixtures containing them by selective absorption in dimethylformamide at below 0 DEG  F., preferably at atmospheric pressure.  In one embodiment an acetylene-containing gas also containing diacetylene and other higher acetylenes enters by line 2 (Fig. 1), is cooled, and fed into absorber 5 which is fed with dimethylformamide by line 6 in an amount sufficient to dissolve diacetylene only.  Diacetylene is stripped from the solution so formed in stripper 11 and solvent returned to the absorber. Unabsorbed gas from the absorber 5 passes to a second absorber 16 fed with dimethylformamide by line 18.  Before entering the absorber, the gas is mixed with a solvent stream withdrawn from the absorber by line 15 and the mixture cooled.  Unabsorbed gases leave by line 19 and are used in part as a stripping gas in stripper 11.  The solution from the bottom of absorber 16 is passed to carbon dioxide fractionator 28 from which CO2 is removed by line 34.  Solution leaves by line 35 and is fed to the threestage flash stripper 41. Solvent is recycled to absorber 16 and in part to the carbon dioxide fractionator by line 42.  Evolved gases pass to the heavy acetylene absorber 72, some solvent being admixed prior to entry.  Heptane at -20 DEG  F. is supplied by line 76.  Acetylene leaves by line 73 to storage and the solution of heavy acetylenes passes to the stripper. In another embodiment (Fig. 2) acetylene, heavy acetylenes, including diacetylene and some non-hydrocarbon gases are absorbed from the feed gas from line 100 in the absorber 104 with dimethylformamide by line 105.  Solvent is admixed with the gas prior to cooling and entering the absorber.  Unabsorbed gases leave by line 106. Solution from line 107 passes to the fractionator 108 to which some dimethyl-formamide is supplied by line 126.  A gas, principally carbon dioxide, leaves by line 109.  Solution passes to the two-stage flash stripper 115, from the top of which acetylene and heavy acetylenes are removed by line 136.  The bottom section is operated so that at the top, all acetylenes including diacetylene are stripped from the solvent.  A stream is taken from this bottom section comprising acetylene, diacetylene, other acetylenes and solvent and led into the diacetylene stripper 173 operated in two stages, acetylenes other than diacetylene being recovered at the top and mixed with acetylene from the two-stage stripper 115, diacetylene being recovered from the bottom section and solvent for recycle from the bottom.  Off-gas from the primary absorber 104 may be used as stripping gas. Acetylenes in line 136 pass to the heavy acetylene absorber 142 to which the toluene is supplied by line 145.  The feed gas is mixed with solvent prior to cooling and entering the absorber. Acetylene leaves by line 143 and a solution of higher acetylenes in toluene passes by line 146 to stripper 147 from which high acetylenes leave by line 148. Specification 831,261 is referred to.ALSO:Acetylenes are recovered from gas mixtures containing them by selective absorption in dimethylformamide at below 0 DEG  F., preferably at atmospheric pressure.  In one embodiment <FORM:0831262/IV (b)/1> <FORM:0831262/IV (b)/2> an acetylene-containing gas also containing diacetylene and other higher acetylenes enters by line 2 (Fig. 1), is cooled, and fed into absorber 5 which is fed with dimethylformamide by line 6 in an amount sufficient to dissolve diacetylene only.  Diacetylene is stripped from the solution so formed in stripper 11 and solvent returned to the absorber.  Unabsorbed gas from the absorber 5 passes to a second absorber 16 fed with dimethylformamide by line 18. Before entering the absorber, the gas is mixed with a solvent stream withdrawn from the absorber by line 15 and the mixture cooled. Unabsorbed gases leave by line 19 and are used in part as a stripping gas in stripper 11.  The solution from the bottom of absorber 16 is passed to carbon dioxide fractionator 28 from which CO2 is removed by line 34.  Solution leaves by line 35 and is fed to the three-stage flash stripper 41.  Solvent is recycled to absorber 16 and in part to the carbon dioxide fractionator by line 42.  Evolved gases pass to the heavy acetylene absorber 72, some solvent being admixed prior to entry.  Heptane at -20 DEG  F. is supplied by line 76.  Acetylene leaves by line 73 to storage and the solution of heavy acetylenes passes to the stripper.  In another embodiment (Fig. 2) acetylene, heavy acetylenes, including diacetylene and some nonhydrocarbon gases are absorbed from the feed gas from line 100 in the absorber 104 with dimethylformamide by line 105.  Solvent is admixed with the gas prior to cooling and entering the absorber.  Unabsorbed gases leave by line 106.  Solution from line 107 passes to the fractionator 108 to which some dimethylformamide is supplied by line 126.  A gas, principally carbon dioxide, leaves by line 109. Solution passes to the two-stage flash stripper 115, from the top of which acetylene and heavy acetylenes are removed by line 136. The bottom section is operated so that at the top, all acetylenes including diacetylene are stripped from the solvent.  A stream is taken from this bottom section comprising acetylene, diacetylene, other acetylenes and solvent and led into the diacetylene stripper 173 operated in two stages, acetylenes other than diacetylene being recovered at the top and mixed with acetylene from the two-stage stripper 115, diacetylene being recovered from the bottom section and solvent for recycle from the bottom.  Off-gas from the primary absorber 104 may be used as stripping gas. Acetylenes in line 136 pass to the heavy acetylene absorber 142 to which the toluene is supplied by line 145.  The feed gas is mixed with solvent prior to cooling and entering the absorber. Acetylene leaves by line 143 and a solution of higher acetylenes in toluene passes by line 146 to stripper 147 from which high acetylenes leave by line 148.  Specification 831,261 is referred to.