Design and optimization of fully thermally coupled distillation columns part 2: Application of dividing wall columns in retrofit

This paper addresses the application of dividing wall columns in retrofit. It emphasizes the need to take maximum advantage of the existing hardware with minimum capital outlay. Based on this study, several practical issues associated with the application of the dividing wall column in retrofit have been identified and as a result, its thermodynamically equivalent arrangements, such as the prefractionator arrangement and the Petyluk column, are often recommended instead. A case study involving the improvement of energy efficiency and capacity expansion of the NGL separation train has been illustrated to demonstrate the analysis involved.