Process Modelling and Optimization of Liquefied Petroleum Gas (LPG) Production in a Gas Processing Unit

Abstract

In this work, Techno-Thermoeconomic Analysis has been performed for an entire Natural Gas Processing Plant (NGPP) to analyze and evaluate the potential scenarios for improving the economic and energy conditions of the unit. The interest is driven by the need to optimize the quality and yield of Liquefied Petroleum Gas (LPG) without hampering the Sales of gas conditions. Sales gas is the primary consumer product of the GPP. The steady-state model has been developed and validated using ASPEN HYSYS. ASPEN Economic Analyzer has been employed to identify cost intensive areas of the unit and to explore options to maximize profits from the Plant. ASPEN Energy Analyzer (AEA) was then utilized to determine energy exhaustive operating units of the plant, and alternatives to reduce energy consumption were suggested based on rigorous Pinch Analysis (PA). Exergy Analysis is executed to determine the exergy efficiency, which, being an indicator of thermal performance, assists in locating the in-efficient operating units having the highest exergy destruction. Economic Analysis indicates improvement in overall product sales when feed gas temperatures are decreased for the NGL Recovery section. Similarly, Exergy analysis showcases significant efficiency improvement potential in the NGL Fractionation train. The exergy efficiency of the base case can be improved by 68%, and the exergy destruction is reduced by 62% when the stream entering the recovery section is pre-heated.