Consider thermally coupled distillation

Abstract

Over the last 20 years, the energy efficiency of distillation systems has significantly improved--so much so that it often is stated that further attempts to reduce energy consumption are not justified. Because reboilers can often be operated with low-grade heat and condensers reject heat at ambient temperature, it is argued that energy efficiency improvements are not really worthwhile. This, however, overlooks two important points: (1) Energy consumption is directly related to vapor generation in a column. If energy consumption is reduced, then so is the vapor flow within the column. Lowered vapor flow means that column diameter can be reduced, cutting capital costs as a result. (2) Energy saving will become more important in the ever more environmentally conscious society. Legislation promoting energy efficient processes already has been enacted in some European countries. Therefore, there are incentives for looking again at distillation systems and their energy consumption, especially as reductions often lead to capital cost savings.