Optimization and Economic Analysis for Small-Scale Movable LNG Liquefaction Process with Leakage Considerations

In this study, exergy and economic analysis were conducted to gain insight on small-scale movable LNG liquefaction considering leakage. Optimization and comparison were performed to demonstrate the quantitative results of single mixed refrigerant, dual nitrogen expansion, and the propane pre-cooling self-refrigeration processes. For the optimization, exergy efficiency was used as the objective function; the results showed that exergy efficiencies are 38.85%, 19.96%, and 13.65%, for single mixed refrigerant, dual nitrogen expansion, and propane pre-cooling self-refrigeration, respectively. Further, the cost analysis showed that the product cost of each process is 4002.3 USD/tpa, 5490.2 USD/tpa, and 9608.5 USD/tpa. A sensitivity analysis was conducted to determine parameters that affect exergy and cost. The SMR process is the most competitive in terms of exergy efficiency, product cost, and operability, without considering makeup facilities.