Patent ID: 6500310
Filing Date: 2002-12-31
Classification: B01D,C02F

Abstract:
A process for treatment of a waste water feed stream originating from the production of styrene monomer and propylene oxide and containing at least hydrocarbons and salts to yield a clean water product, a concentrated brine product and a hydrocarbon-rich product, which process comprises the steps of:(a) feeding the waste water feed stream into a first distillation column at a stage in the range of from 0.05n to 0.15n from the top, wherein n represents the total number of theoretical stages of the first distillation column and has a value in the range of from 20 to 40; (b) drawing off a vapor stream at a stage in the range of from 0.55n to 0.75n from the top and feeding said vapor stream into the bottom of a second distillation column having m theoretical stages, with m having a value in the range of from 3 to 10; (c) drawing off the clean water product as the top fraction from the second distillation column and drawing off a bottom stream from the second distillation column, which is fed back into the first distillation column below the draw off of the vapor stream in step (b) at a stage in the range of from 0.60n to 0.85n from the top; (d) drawing off the concentrated brine product as the bottom fraction of the first distillation column; and (e) drawing off the hydrocarbon-rich product as the top fraction of the first distillation column.