Modeling and optimization of natural gas liquefaction process for reducing energy consumption

Abstract

Because of limited fuel reserves, increasing prices of oil and growing concerns about the environment, natural gases are receiving attention as low-carbon, eco-friendly fuels. Natural gases have very large gas-to-liquid volume ratio, so the liquefaction process is essential to reduce volume of natural gases. Through the liquefaction process, natural gas becomes liquefied natural gas (LNG). LNG has a comparative advantage in terms of transport and safety. There are several kinds of natural gas liquefaction process. Among the liquefaction processes, propane pre-cooled mixed refrigerant (C3MR) process is the most widely used natural gas liquefaction process to date. In this study, a steady-state simulation of the C3MR process was performed using ASPEN HYSYS™ and it was optimized to reduce energy consumption. Optimization formulation is developed to minimize operating cost of the process. Optimization variables are temperature, pressure, and flow-rate of refrigerant and composition of the mixed refrigerant.