A comprehensive comparison of the turbo-expander, Joule-Thomson, and combination of mechanical refrigeration and Joule-Thomson processes for natural gas liquids production

Abstract

Natural gas liquids production from natural gas streams is essential for energy diversification, economic development, environmental sustainability, and ensuring a stable and reliable energy supply. However, the NGL recovery process is associated with high energy consumption and significant environmental impact. This study compares three common NGL recovery processes based on turbo expander, Joule-Thomson, and combined processes through a 4E analysis approach. The 4E analysis framework includes four key aspects: environmental impact, energy consumption, exergy efficiency, and economic feasibility. By simultaneously considering these factors, a comprehensive assessment can be achieved. The specific energy consumption is optimized, and the results show that the specific energy consumption of the turbo-expander process is 164.4 % and 181.7% lower than the Joule-Thomson and combined processes, respectively. Also, the exergy efficiency for the turbo-expander, Joule-Thomson, and combined processes is 75, 71, and 60%, respectively. In addition, the ethane recovery rates for the turbo-expander, Joule-Thomson, and combined processes are 74.85%, 31%, and 69.87%, respectively. Economic analysis also indicated that the turbo-expander is more cost-effective than the other two processes, and the production cost in the turbo-expander process is lower by 45.45 and 54.54%, respectively. In addition, the turbo-expander process emits less carbon dioxide during NGL production.