Distillation esp. of crude oil in pre- and main columns - includes using temp.-matched side stream feed to reduce external heating energy requirements

摘要

In distillation of complex mixts. (esp. atmos. distillation of crude oil), the main column is preceded by one or more pre-columns, the bottom product of the last pre-column is fed to the main column via a radiant preheater, and the initial mixt. is preheated, before and between the pre-columns, only by the waste heat of the product and/or the energy extracted from the circulating return flows of the main column. The novelty is that side-streams are withdrawn from one or more pre-columns and fed to the main column below fittings at which the boiling conditions and temps. of the liqs. flowing from the fittings and of the side-streams are as close as possible. USE/ADVANTAGE - Esp. for atmos. distillation of crude oil, but also for distillation of products from hydrocracking and fluid catalytic cracking. The quantity of last pre-column bottom prod., to be preheated in the radiant preheater, is reduced so that the external energy requirements are reduced, e.g. to 6kJ/kg. product (using one pre-column) or 20 kJ/kg. product (using two pre-columns).