Patent GB-831261-A (GB)
Title: Recovery of acetylene from gases
Inventor: KOBLE ROBERT ADAMS
IPC: C07C7/11
Filed: 1956-09-26
Abstract: <PICT:0831261/III/1> Acetylene and higher acetylenes together with some non-hydrocarbon material are separated from gas mixtures containing then by absorbing the acetylenes and some non-hydrocarbon gases in a solvent, removing from the solution so obtained at least some of the non-hydrocarbons and desorbing, and then separating the acetylenes.  The preferred solvent is dimethylformamide used at below 0 DEG  C. as described in Specification 831,262, but other selective solvents such as dimethylacetamide, butyrolactone and N-methyl-2-pyrrolidone can be used.  The gas mixture from pipe 30 obtained from the manufacture of carbon black is quenched in tower 31 with water, liquids separated in knock-out drum 34, dried in drier 37, cooled to - 30 DEG  to - 70 DEG  F. and passed into absorber 41 at about 15 p.s.i.a. into the head of which dimethylformamide at - 30 DEG  to - 70 DEG  F. is led by line 42.  Unabsorbed gas leaves by line 43 and the solution by line 44.  The latter is heated and pumped into flash drum 49 where nitrogen and some carbon dioxide are evolved and recycled by line 50 to the absorber.  The solution is further heated and pumped into stripper 55.  All absorbed gases are evolved and the solvent is recycled by line 56, cooled and returned to the absorber.  The gases leaving by line 59 are cooled in cooler 60 and liquid separated in accumulator 62 and recycled by line 63.  The gases are further cooled, condensed liquid again separated, and the gases pumped into absorber 71.  N-heptane is passed into the top to remove higher acetylenes, acetylene and carbon dioxide leaving by line 73.  The heptane solution of higher acetylenes is passed to stripper 79, heptane being removed and returned to absorber 71 by line 72.  Higher acetylenes pass by line 80 to accumulator 81 from which a small reflux for the stripper is taken and higher acetylenes leave the system by line 82.  The gases from line 73 pass into absorber 83 and ethanolamine enters by line 93.  Acetylene leaves by line 84 and a solution of carbon dioxide passes by line 85 into stripper 88, carbon dioxide leaving by line 89 and ethanolamine being recycled to absorber 83 by line 90.  For separating higher acetylenes from acetylene other C6-C10 hydrocarbons may be used such as n-hexane, n-nonane, iso-octane, benzene, toluene, xylene, cyclohexane and methylcyclohexane.  In a modification, all non-hydrocarbon gases are removed in flash drum 49 and the final step of separating acetylene and carbon dioxide omitted.ALSO:Acetylene and higher acetylenes together with some non-hydrocarbon material are separated from gas mixtures containing them by absorbing acetylene, higher acetylenes and some non-hydrocarbon material in a solvent, removing from the solution so obtained at least some of the non-hydrocarbon material and desorbing and then separating the acetylene and higher acetylenes. The preferred solvent is dimethylformamide used at below 0 DEG  C. as described in Specification 831,262, but other selective solvents such as dimethylacetamide, butyrolactone and N-methyl-2-pyrrolidone can be used.  The gas mixture from pipe 30 obtained from the manufacture of carbon black is quenched in tower 31 with water, liquids separated in knock-out drum 34, dried in drier 37, cooled to - 30 DEG  to - 70 DEG  F. and passed into absorber 41 at about 15 p.s.i.a. into the head of which dimethylformamide at - 30 DEG  to - 70 DEG  F. is led by line 42.  Unabsorbed gas leaves by line 43 and the solution by line 44.  The latter is heated and pumped into flash drum 49 where nitrogen and some carbon dioxide are evolved and recycled by line 50 to the absorber.  The solution is further heated and pumped into stripper 55.  All absorbed gases are evolved and the solvent is recycled <PICT:0831261/IV (b)/1> by line 56, cooled and returned to the absorber.  The gases leaving by line 59 are cooled in cooler 60 and liquid separated in accumulator 62 and recycled by line 63.  The gases are further cooled, condensed liquid again separated, and the gases pumped into absorber 71.  N-heptane is passed into the top to remove higher acetylenes, acetylene and carbon dioxide leaving by line 73.  The heptane solution of higher acetylenes is passed to stripper 79, heptane being removed and returned to absorber 71 by line 72.  Higher acetylenes pass by line 80 to accumulator 81 from which a small reflux for the stripper is taken and higher acetylenes leave the system by line 82.  The gases from line 73 pass into absorber 83 and ethanolamine enters by line 93. Acetylene leaves by line 84 and a solution of carbon dioxide passes by line 85 into stripper 88, carbon dioxide leaving by line 89 and ethanolamine being recycled to absorber 83 by line 90. For separating higher acetylenes from acetylene other C6-C10 hydrocarbons may be used such as n-hexane, n-nonane, isooctane, benzene, toluene, xylene, cyclohexane and methylcyclohexane.  In a modification, all non-hydrocarbon gases are removed in flash drum 49 and the final step of separating acetylene and carbon dioxide omitted.