Analysis of Heat Demand and Supply in Multicomponent Distillation Systems

The energy analysis of distillation systems, especially the identification of heating and cooling zones in a column, is useful in the application of various energy-saving technologies to the systems. A method of analyzing the heat demand and supply for a binary system has been established, but there are few practical applications for multicomponent systems. One of the reasons is that the installation of an intermediate heat exchanger in a multicomponent distillation system changes the composition profile. We propose an energy analysis method for multicomponent distillation systems. With this method we defined appropriate locations of an intermediate heat exchanger, that is, heating and cooling zones, and its maximum exchangeable energy load. Especially, the relationships between the patterns of heating and cooling zones and the locations of pinch zones are investigated. As a result, the upper and lower hypothetical pinch zones in a multicomponent distillation column terminate the heating zone at lower temperature, and the cooling zone at higher temperature, respectively. The conclusions are generalized by using graphical representations of the composition profiles