NGL recovery enhancement for GUPCO trans gulf gas plant by using new applicable technique

Abstract

It is known that the price of natural gas liquids (NGL) is higher than that of natural gas from which it is derived, so more modifications needed for existing plants to derive more NGL is economically accepted point of view. The main objective of the present work is to present the method applied on Trans gulf (T/G) gas plant to overcome its performance decrease happened after the plant feed gases becoming leaner than its design margin and hence it led to a great decrease in the plant NGL recovery. This achieved by introducing a new simple modification to the existing process scheme obtained by using a condensate stream to enrich the reflux of the de-ethanizer tower so more recovery is obtained. In order to accomplish that goal, some changes in the existing process operating conditions were needed. A simulation is used in this study to examine the existing and the introduced modification utilizing ASPEN-HYSYS software version 8.4 using Peng-Robinson equation of state (EOS). The simulation of the existing plant results in a better understanding of the plant behavior in the different iterations to reach the maximum benefits. The plant after suffering from low butane recovery from its feed gas and which considered as a figure to the plant efficiency, it increased by this method from 38 % to reach 86-90 % butane recovery and its LPG production increased by 170% to be ≈ 122 tonne/day instead of ≈ 44 tonne/day while only losing ≈ 16 tonne/day of condensate production. An optimization to the new method is done in this paper so that it doesn't intercept with the existing plant equipment performance for the process safety triggers. Also, the last section of the study describes the economic point of view and the return on investment (ROI) how it was paid back only in 7 days. This modification can be taken as a guideline for both new and existing LPG plants which use only propane refrigeration systems for LPG recovery to increase their profits with the lowest cost possible.