Patent GB-590905-A (GB)
Title: Process for the separation of normally gaseous mixtures
IPC: C07C7/11
Filed: 1944-09-28
Abstract: <PICT:0590905/III/1> A desired gaseous fraction is separated from a mixture, for example, of gaseous hydrocarbons, by commingling the mixture, introduced at 1, with a stream of liquid absorbent from line 3, and a stream of recycle gas from line 2, passing through a cooler 4 under superatmospheric pressure to a separator 5, removing lighter gases (which constitute the recycle gas) from the separated liquid phase in a stripper 9, and then recovering the desired gaseous fraction from the stripped absorbent in a fractionator 18.  The pressure of the liquid absorbent is then reduced by passing through a valve 27, and a gaseous fraction is removed in a flash evaporator 28, the absorbent passing back to line 3 via a heat-exchanger 34 and down an absorber 37 to recover any of the desired fraction entrained in the undissolved gases from the separator 5.  The gases from the fractionator 18 pass through a cooler 48 and separator 50 to a further fractionating system 54, 55, from which the desired fraction is removed at 64, the remainder passing out of the system through an expansion valve 73 and the heat-exchanger 34.  In a modification described with reference to a flow sheet (Fig. 2, not shown) the liquid absorbent stripped of lighter gases, but still retaining the desired fraction, is mixed with a second liquid absorbent and a second recycle gas, the desired fraction being separated in a system similar to that constituted by the stripper 9 and the absorber 37. Examples describe the separation from hydrocarbon mixtures of fractions containing 95 per cent. ethylene, 94 per cent. propane-propylene, and 96 per cent. butane-butylene.  In the separation of hydrocarbon mixtures, a gasoline fraction, naphtha, or an olefinic naphtha fraction may be used as the liquid absorbent.ALSO:A desired gaseous fraction is separated from a hydrocarbon mixture, by commingling the mixture introduced at 1, with a stream of liquid absorbent from line 3, and a stream of recycle gas from line 2, passing through a cooler 4 under superatmospheric pressure to a separator 5, <PICT:0590905/IV/1> removing lighter gases (which constitute the recycle gas) from the separated liquid phase in a stripper 9, and then recovering the desired gaseous fraction from the stripped absorbent in a fractionator 18.  The pressure of the liquid absorbent is then reduced by passing through a valve 27, and a gaseous fraction is removed in a flash evaporator 28, the absorbent passing back to line 3 via a heat-exchanger 34 and down an absorber 37 to recover any of the desired fraction entrained in the undissolved gases from the separator 5.  The gases from the fractionator 18 pass through a cooler 48 and separator 50 to a further fractionating system 54, 55, from which the desired fraction is removed at 64, the remainder passing out of the system through an expansion valve 73 and the heat-exchanger 34.  In a modification described with reference to a flow sheet (Fig. 2, not shown) the liquid absorbent stripped of lighter gases, but still retaining the desired fraction, is mixed with a second liquid absorbent and a second recycle gas, the desired fraction being separated in a system similar to that constituted by the stripper 9 and the absorber 37. Examples describe the separation of fractions containing 95 per cent ethylene, 94 per cent propane-propylene, and 96 per cent butane-butylene.  A gasoline fraction, naphtha, or an olefinic naphtha fraction may be used as the liquid absorbent.