Rigorous Method of Minimum Energy Calculation 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. This paper describes a research work where the rigorous minimum energy calculation method is extended to a fully thermally coupled distillation column system, also called Petlyuk column. In the solving procedure, a bounded Newton homotopy method is used to detect the optimum point of operation for the column system, which is described with the full set of MESH equations. There are no restrictions for the thermodynamic models used. The results are promising and indicate that the numerical challenges encountered when rigorously solving complex distillation problems can be tackled by utilising modern numerical solving approach.