Energy Integrated Distillation Column Sequence by Driving Force Method and Pinch Analysis

Abstract

Distillation is a common separation process since its emergence in the early 20th century due to its capability for mass production without compromising the product(s) quality. However, the energy efficiency is still become the challenge for the industry players. Since then, they put so much effort in ensuring the energy efficiency of the process. It is not only for economic purpose but also to address the environmental issue whereby the legislation become stringent over the years. Therefore, this paper aims to investigate the energy efficiency of distillation column sequence by using the pinch analysis method. Rigorous simulation of the distillation for component n-butane, n-hexane, n-heptane and n-nonane has been carried-out for 5 different sequences namely direct, indirect, driving force sequence (indirect-direct), direct-indirect and split for energy analysis. Aspen HYSYS V9 has been used for the simulation while the data was extracted for pinch analysis including the construction of problem table algorithm to obtain the minimum cooling and heating load for each sequence. The results that were analyzed and compared including total heat load, heating load and cooling load. Then the grid diagrams for the best sequence was constructed. From the results of energy analysis, all distillation sequences except for direct-indirect sequence recorded further energy saving compared to the base case whereby the highest saving is driving force sequence at 6.31% total energy saving. It also recorded the highest percentage of heating and cooling load at 4.85% and 9.05% respectively. This paper also strengthens the advantage of driving force method in determining the best sequence since it was proved to produce lower energy consumption compared to others. Then, the energy can be further reduced by using the pinch analysis. Therefore, for this case study, it can be concluded that the heat integration via pinch analysis is a promising method for further saving for any distillation column sequence.