Heat-Integrated Distillation Columns as a Retrofit Cannot Bring Energy Savings to the Ethylene Plant

Abstract

Separation by distillation is an energy-intensive process. Approximately 40% of energy use in the petrochemical industry is associated with separation by distillation. The heat-integrated distillation column (HIDiC) is a process intensification technology, which aims to reduce the energy required by the distillation process. A study was performed to determine the energy savings that could be achieved by using HIDiC as a retrofit of two critical distillation columns in the ethylene process (ethylene fractionator and deethanizer). The aim was to assess the energy savings of an individual HIDiC and relate it to the energy consumption of the plant as a whole. The outcome of this study is that HIDiC could lower the energy demand, but this itself did not translate into energy savings for the overall plant in either case. The HIDiC ethylene fractionator increased the energy consumption of the overall plant by 16% and the HIDiC deethanizer by 50%. The reasons for this are discussed thoroughly in this article.