Improving efficiency of distillation with new thermally-coupled configurations of columns

New, simplified thermally coupled systems of columns for ternary separation, containing one one-way and one two-way connection between the columns, were recently proposed by Agrawal and Fidkowski (1999). The new thermally coupled systems are easier to control and often consume no more heat than the fully coupled systems. Thermodynamic efficiencies of the new systems distilling ideal saturated liquids into pure liquid product streams are calculated and compared with efficiencies of known distillation configurations. The new configurations significantly extend the zone of feed compositions where thermally coupled configurations are the most efficient. The new configurations appear to be particularly useful when separation of components is difficult. The new configurations can be instantly and effortlessly compared with other distillation schemes by using a computer program to calculate the efficiencies of various possible configurations for ternary distillation.