GB449369A - Method of utilising the waste heat in the production of benzene from saturated wash oil - Google Patents

Abstract

In the recovery of benzene from saturated wash oils in which the wash oil is circulated continuously between a distilling apparatus at high temperature and a gas scrubbing plant at a lower temperature, the mixtures of benzene and steam issuing from the distilling apparatus <PICT:0449369/III/1> is used as heating agent in an evaporator for producing steam. Saturated wash oil already preheated to 100 DEG C. by heat exchange with the treated oil is heated to 140 DEG C. in a heater 1 by steam passing through a coil 18. The heated oil passes through a pipe 3 and feed pipe 4 into a column still 5 where it is stripped from benzene by steam supplied through a pipe 6, the purified oil being returned to the gas washing plant through a pipe 19 and being used on its way to preheat the saturated oil. The benzene vapours and steam pass off from the column through a pipe 9 and on their way to the final condenser 11 and separator 12 are used to produce steam by passing them through the tubes of an evaporator 15 to which hot condensate from the coil 18 is supplied through pipes 21, 22. The steam produced is injected by a steam ejector 30 through pipes 29, 31 into the column 5. The pressure on the hot condensate may be reduced prior to its evaporation by admitting it through a reduction valve 36 into a vessel 32 and the steam thus produced is passed through a pipe 40 to mix with the steam in the pipe 31.