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

In the distillation process, heat is supplied at a feed heater and a reboiler, and cooled at an overhead condenser. In the conventional distillation process, the supplied heat at the reboiler is discarded in the overhead condenser. Energy savings were fundamentally attained as a result of the maximized heat recovery duty in the feed heater using the heat of the bottom stream and then, the utility steam rate to the feed heater is managed to be reduced. To achieve further energy saving in the 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 stream and the overhead product stream. The compressor-1 treats the reflux stream and the compressor-2 treats the overhead stream. The reboiler duty is satisfied by the recuperated heat of a discharged stream from the compressor-1 and the feed heater duty is recuperated by a discharged stream from the compressor-2 by adiabatic compressions. Process-simulation (PRO/II (TM) ver.8.1, Invensys) case study confirmed that despite there being almost no more energy saving potential in the conventional process, the advanced process with SHRT could reduce the energy consumption significantly by using the recuperated heat of the overhead vapor.