Energy improvement for NGLs direct-indirect sequence fractionation unit

Abstract

The objective of this paper is to present the study and analysis of the energy saving improvement for the natural gas liquids (NGLs) direct-indirect sequence fractionation unit by using driving force method. To perform the study and analysis, the energy efficient NGLs fractionation sequence methodology has been developed. Accordingly, the methodology consists of four hierarchical steps; Step 1: Existing Sequence Energy Analysis, Step 2: Optimal Sequence Determination, Step 3: Optimal Sequence Energy Analysis, and Step 4: Energy Comparison. The capability of this methodology is tested in designing energy efficient distillation column sequence for NGLs fractionation process, which consists of nine compounds (methane, ethane, propane, i-butane, n-butane, i-pentane, n-pentane, n-hexane, n-heptane) with eight direct-indirect sequence of distillation columns. The results show that the maximum of 6.44 % energy reduction is able to achieve using sequence changes suggested by the driving force method. It can be concluded that, the sequence determined by the driving force method is able to reduce energy used for NGLs fractionation process. All of this findings show that the methodology is able to design minimum energy distillation column sequence for NGLs fractionation process in an easy, practical and systematic manner.