GB766120A - Improvements in or relating to the distillation of benzolised wash oil - Google Patents

Abstract

<PICT:0766120/III/1> In a process for the steam distillation of benzolized wash oil in a fractionating column with return to the head of the column of a portion of the condensed distillate (freed from water), part of the liquid flowing down the upper section of the column is withdrawn therefrom and is heated to at least partial vaporization in an external heater, the vapours from which are passed back into the column at a position above the liquid take-off. By this means a crude light oil in which the proportion of components boiling below 180 DEG C. amounts to 95 per cent is readily obtained as distillate, without excessive use of live steam. Benzolized wash oil is supplied through conduit 1, heatexchanger 2 and conduit 3 to heating coil 9 which is disposed in a convection zone of furnace 4. After flowing through coil 9 and also through coil 10, which is in the radiation zone of the furnace, the oil, now at a temperature of about 180 DEG C., passes through reducing valve 11 and conduit 12 into the stripping section of column 13. Direct steam (12 to 15 kg. per cubic metre of wash oil) is fed to the column through conduit 16. Stripped wash oil is withdrawn from the column through conduit 17. The vapours leaving the head of the column are passed through conduit 18 and heat-exchanger 2 to condenser 19. The resultant condensate is led to receptacle 21, wherein water separates from light oil. The water is withdrawn through pipe 22. Part of the light oil is withdrawn as product through pipe 23, and the remainder is pumped through conduit 26 to the top tray of column 13. Part of the reflux reaching tray 27 is withdrawn through conduits 28 and 30 to collector 31; it is then pumped through coil 34 which is disposed in a convection zone of furnace 4. The mixture leaving coil 34 is passed through reducing-valve 35 and conduit 36 into vaporizing chamber 37. Non-vaporized residue is withdrawn from chamber 37 through pipe 38. The vapours from chambers 37 are introduced into the column through conduit 39. Spent wash oil may be regenerated in the process by introducing it through conduit 40 into collector 31, and withdrawing pitchy residue through pipe 38.