Reduce Costs and Energy Consumption of Deethanizing and Depropanizing Fractionation Steps in NGL Recovery Process

Abstract

In this work, our aim is how to utilize the dividing wall column (DWC) to improve the performance in deethanizing and depropanizing fractionation steps in NGL processing. Starting from an initial conventional column sequence, the initial designs for the conventional DWC and top dividing wall column (TDWC) were obtained by maintaining the number of trays. In succession, they were optimized to reduce the energy consumption. The results show that the DWC and TDWC offer many benefits by decreasing the operating cost including refrigeration cost, as well as reboiler and condenser duty. Furthermore, by using DWC, the purity and recovery of ethane also increases, particularly, from 95 to around 97% and 95 to more or less 98%, respectively. Based on these results, the comparison of performance between the conventional DWC and TDWC was analyzed. Then the influence of utility prices on the operating cost saving of conventional DWC and TDWC was studied. In addition, heat integrating on the top and interreboiling the bottom section of the DWC were also applied to improve the performance of the DWC.