Advanced energy saving in distillation process with self-heat recuperation technology

Abstract

In the distillation process, heat is supplied at a feed heater and a reboiler, and an overhead stream is cooled at a condenser. Almost all of the supplied heat at the reboiler in the conventional distillation process is discarded in the overhead condenser. Conventional energy savings of the distillation processes were fundamentally attained as a result of heat recovery duty in the feed heater being maximized by using the heat of the bottom stream, which enabled the utility (steam or hot oil) rate to the feed heater to be reduced. To achieve further energy saving in the distillation process, “self-heat recuperation technology” (SHRT) was adopted. In this technology, two compressors are installed in the overhead vapor line, which consists of the reflux and the overhead product streams. A compressor (compressor-1) treats the reflux stream and the other compressor (compressor-2) treats the overhead stream. The reboiler duty is supplied by the recuperated heat of the discharged stream from compressor-1 and the feed heater duty is supplied by that from compressor-2, by adiabatic compressions. It could be found that the advanced process with SHRT was able to reduce the energy consumption significantly by using the recuperated heat of the overhead vapor.