A Rigorous Minimum Energy Calculation Method for a Fully Thermally Coupled Distillation System

Previously, Tanskanen and Pohjola (2000) and Tanskanen and Malinen (2005) have presented a method of rigorous minimum energy calculation for non-ideal multicomponent distillation. The method is based on column simulation with a large number of equilibrium stages to mimic infinitely high columns, and it has been successfully tested with simple distillation column systems. In this paper the rigorous minimum energy calculation method is extended to a fully thermally coupled distillation column system, also known as a Petlyuk column. This paper introduces not only the theoretical background of the applicable solving strategy, but also practical and useful solving tools capable of solving complex distillation column models. In the solving procedure, a modified bounded Newton homotopy method is used to detect the optimum point of operation for the column system, which is described with a full set of MESH equations. The results are promising and indicate that the numerical challenges encountered when rigorously solving complex distillation column problems can be tackled by utilising a modern numerical solving approach.