GB896464A - Improvements in or relating to separation processes by distillation - Google Patents

Abstract

<PICT:0896464/III/1> In a distilling process for separating the components of a mixture of substances capable of separation by distillation, e.g. a mixture of light hydrocarbons, the feed to the distillation column is prepared by intimately contacting the mixture with the overhead vapours of the column to establish a gas-liquid equilibrium, cooling and condensing the gas and liquid phases which are in equilibrium and separating the liquid together with the condensate, the separated liquid then being employed as the feed. As shown, the column 2 is operated under pressure and is divided by a draw-off tray 3, adapted to pass vapour but not liquid, into a distillation section 4 and a mixing section 5, the latter being provided with bubble cap trays 6 and 7 or other contact means adapted to effect fine distribution of one phase in the other and effect a gas-liquid equilibrium. A mixture of C1-C4 hydrocarbons is passed through line 1 to mixing section 5. C3 and C4 hydrocarbons are withdrawn from the base of the distillation section at 8. The vapours and liquid are withdrawn from the mixing section 5 at 9 and 10 respectively and are passed together through a cooler 11 where more liquid condenses. The gases and liquid in the cooler (which are no longer in equilibrium) are passed separately to an accumulator 14 through lines 12 and 13 respectively. In the accumulator the liquid and gases move countercurrently through the packed dome 15 and equilibrium is again established between them. C1 and C2 hydrocarbons are withdrawn at 17 and the accumulated liquid is withdrawn at 18 and returned, as fed, to the distillation section 4.