Retrospective and future perspective of natural gas liquefaction and optimization technologies contributing to efficient LNG supply: A review

Despite recent falls in oil and gas prices, the LNG industry remains vibrant with several plants ready for deployment in 2017/2018, and others awaiting final investment decisions. With expected growth in LNG consumption, the higher activity in LNG industry is likely to continue. Considering ongoing activity levels in the LNG market, a retrospective review of natural gas liquefaction technologies and optimization methodologies presented together with implications for their future directions. Variants of mixed-refrigerant-based technologies continue to dominate the onshore LNG plant market. For the offshore LNG market, non-flammable-refrigerant-based expander technologies being pursued, due to their safety and space requirements. Currently, deterministic and stochastic approaches dominate the optimization of LNG process plants with the preferred objective of compression energy minimization. However, when a holistic approach considering economical, technical, process safety/reliability is applied, multiple decision criteria are very frequently occurring, giving stochastic approach an upper hand. Increased activity in the use of process knowledge in guiding the stochastic approach for meaningful multi-objective solutions in NG liquefaction is foreseeable.