Process for separating higher hydrocarbons from gas mixtures containing acetylene and/or ethylene

Acetylene and ethylene are obtained by vaporizing, preheating to 400 DEG -500 DEG C. at atmospheric pressure and pyrolysing a hydrocarbon mixture boiling in the range 35 DEG -107 DEG C. to obtain a gas mixture containing acetylene and/or ethylene, contacting the gas with a stream of the feed hydrocarbon at -60 DEG to -80 DEG C. and 10 to 20 atmospheres to absorb C3\sB hydrocarbons and combining the used washing liquid, preheated to below the boiling point, with the preheated feed to the pyrolysis. A partial stream of a benzine to be pyrolysed amounting to 30-60% of the total feed in line 16 is taken off for washing purposes by pump 17 and line 18. The pyrolysed gas mixture enters by line 1 and is progressively cooled in heat exchangers 2, 6 and 8 and simultaneously contacted with small amounts totalling about 10% of the washing liquid to remove the more soluble components of the gas, the solution obtained being introduced by lines 25, 26 and 27 into the washing column 24. There the gas from line 9 contacted with benzine and condensed acetylene and ethylene in absorption section 23, the condensed gas being obtained from condensation section 32 and from the conventional recovery unit 3. At the bottom of the column in expelling unit 34, condensed acetylene and ethylene are blown out of the liquid at -40 DEG C. by residual gas from separating unit 3 introduced into evaporator 36. The used washing liquid in line 28 is heated and mixed in evaporator 29 with the remainder of the benzine from line 16 which has been evaporated and preheated in furnace 13 and the gaseous mixture in line 41 is conducted to pyrolysis.