GB828391A - Improvements in or relating to the removal of benzene and its homologues from an absorbent liquid - Google Patents

Abstract

A process for removing light oil from benzolized wash oil with stripping steam while purifying the wash oil for re-use as debenzolized wash oil comprises first contacting a portion of said wash oil with steam to produce a mixture of steam and oil vapours and to leave as a residue any non-volatile components of the wash oil, <PICT:0828391/III/1> contacting the mixture with the benzolized wash oil, and applying additional heat to the wash oil and residue to said portion whereby a greater amount of said portion is converted to oil vapour than is possible by the use of steam alone. In a preferred embodiment benzolized wash oil is passed through a conventional countercurrent oil-to-oil heat exchanger where it is warmed, and then passed on to a steam or fired heater 12 where the temperature is raised to 160 DEG to 200 DEG C. The hot benzolized oil is introduced into a conventional bubble-cap tray type stripping tower 13 where it is subjected to a countercurrent upward flow of steam which removes the light oil as vapours from the wash oil, the vapours and steam then passing to a rectifying column 17 wherein the light oil is separated into two fractions, one comprising benzol, toluol and xylol and boiling below 145 DEG C. and a heavy naphthalene fraction boiling above 150 DEG C. Rectification is brought about by the provision of a reflux condenser 19 and a fluid separator 20 in which the water is separated from the benzol fraction which is separated into two portions, one being used for product and another being returned to the rectifier as reflux. A purifier 31 into which steam is introduced through a conduit 35 removes the polymerized and non-volatile impurities from the wash oil. Superheated steam is produced in heater 50.