Patent GB-745546-A (GB)
Title: Improvements in or relating to the separation of hydrocarbons
Inventor: CHAMPAGNAT ALFRED
IPC: C10G73/24
Filed: 1953-05-13
Abstract: A process for the extractive crystallization of a hydrocarbon mixture comprises treating the mixture with a urea solution to form a complex slurry, the liquid phase of which consists of an emulsion of urea adduction raffinate and urea solution, containing in suspension a solid adduct with or without solid urea; decanting at least part of the raffinate from the slurry and prior to or duing the separation, stirring the slurry by bubbling an inert gas therethrough, to form an upper raffinate phase and a lower urea phase containing solids; and recovering urea adduction extract from the solid/liquid phase, for example by heating to decompose the adduct.  Raffinate still remaining in the slurry after the greater parts has been decanted may be separated by adding a solvent for the raffinate and stirring by bubbling an inert gas therethrough; the upper phase comprising solvent is then separated from the remaining solid/liquid phase.  The raffinate solvent may be a petroleum distillate having an upper boiling limit below the lower boiling limit of the mixture being treated. Urea solvents referred to are those described in Specification 704,439, [Group III], for example water and/or methanol, and methanol and ethylene glycol with or without water. The urea may contain a small proportion of biuret, as described in Specification 716,068.  The inert gas specified is air.  The process may be used for separating normal paraffins and olefins from mixtures of hydrocarbons, for example from mineral oils such as cracked petroleum distillates and shale oil fractions; the treatment of petroleum distillate fractions of boiling range 80-350 DEG  C. is referred to.  Examples, including a method for continuous operation of the process, are given.ALSO:A process for the extractive crystalization of a hydrocarbon mixture comprises treating the mixture with a urea solution to form a complex slurry, the liquid phase of which consists of an emulsion of urea adduction raffinate and urea solution, containing in suspension a solid adduct with or without solid urea; decanting at least part of the raffinate from the slurry and prior to or during the separation, stirring the slurry by bubbling an inert gas therethrough to form an upper raffinate phase and a lower urea phase containing solids; and recovering urea adduction extract from the solid/liquid phase, for example by heating to decompose the adduct.  Raffinate still remaining in the slurry after the greater part has been decanted may be separated by adding a solvent for the raffinate and stirring by bubbling an inert gas therethrough; the upper phase comprising solvent is then separated from the remaining solid/liquid phase.  The raffinate solvent may be a petroleum distillate having an upper boiling limit below the lower boiling limit of the mixture being treated.  Urea solvents referred to are those described in Specification 704,439, for example water and/or methanol, and methanol and ethylene glycol with or without water.  The urea may contain a small proportion of biuret, as described in Specification 716,068.  The inert gas specified is air. The process may be used for separating normal paraffins and olefins from mixtures of hydrocarbons, for example from mineral oils such as cracked petroleum distillates and shale oil fractions; the treatment of petroleum distillate fractions of boiling range 80-350 DEG C. is referred to.  Examples, including a method for continuous operation of the process, are given.