Patent GB-901963-A (GB)
Title: Recovery of acetylene and ethylene from a gaseous mixture obtained by the pyrolysis of hydrocarbon feed
IPC: C07C7/11
Filed: 1958-10-01
Abstract: Acetylene and ethylene are both recovered from a gaseous mixture obtained by the pyrolysis of a hydrocarbon feed by passing the mixture which also contains heavier hydrocarbons having at least three carbon atoms, through a first contact with a lean oil comprising predominantly hydrocarbons having at least three carbon atoms and in sufficient amount to absorb substantially all of the heavier hydrocarbons, said lean oil including said absorbed heavier hydrocarbons comprising at least a portion of the feed to the pyrolysis, passing the gaseous mixture through a second contact with a selective solvent of sufficient amount to absorb substantially all of the acetylene in the mixture, withdrawing substantially all of the ethylene passing through the second contact and separating the absorbed acetylene from the selective solvent of the second contact. The lean oil is preferably refrigerated to below 60 DEG  F. before used as the first contact.  In a typical example propane is cracked in a regenerative pyrolysis at one half atmospheric pressure at 1800 to 2300 DEG  F. or in a tubular furnace at slightly above atmospheric pressure at 1470 to 1550 DEG  F.  The product gas is first treated to remove carbon dioxide, water, tar-like materials and liquid aromatics and the remainder passes to a lean oil which constitutes at least a portion of the feed where the propylene, propane, methylacetylene and heavier impurities are removed.  The unabsorbed gas mixture consisting chiefly of acetylene, ethylene, ethane, and methane is treated with a solvent such as anhydrous ammonia, acetone, dimethylformamide, or butyrolactone to extract the acetylene which is subsequently recovered by distillation.  The ethylene stream may then be purified by low temperature distillation.ALSO:Acetylene and ethylene are both recovered from a gaseous mixture obtained by the pyrolysis of a hydrocarbon feed by passing the mixture which also contains heavier hydrocarbons having at least three carbon atoms. through a first contact with a lean oil comprising predominantly hydrocarbons having at least three carbon atoms and in sufficient amount to absorb substantially all of the heavier hydrocarbons, said lean oil including said absorbed heavier hydrocarbons comprising at least a portion of the feed to the pyrolysis, passing the gaseous mixture through a second contact with a selective solvent of sufficient amount to absorb substantially all of the acetylene in the mixture, withdrawing substantially all of the ethylene passing through the second contact, and separating the absorbed acetylene from the selective solvent of the second contact.  The lean oil is preferably refrigerated to below 60 DEG F. before used as the first contact.  In a typical example propane is cracked in a regenerative pyrolysis at one half atmospheric pressure at 1800-2300 DEG F. or in a tubular furnace at slightly above atmospheric pressure at 1470-1550 DEG F. The product gas is first treated to remove carbon dioxide, water, tar-like materials and liquid aromatics and the remainder passes to a lean oil which constitutes at least a portion of the feed, where the propylene, propane, methylacetylene and heavier impurities are removed.  The unabsorbed gas mixture consisting chiefly of acetylene, ethylene, ethane, and methane is treated with a solvent such as anhydrous ammonia, acetone, dimethylformamide, or butyrolactone to extract the acetylene which is subsequently recovered by distillation.  The ethylene stream may then be purified by low temperature distillation.