Integrating Recovered Jetty Boil-off Gas as a Fuelin an LNG Plant

摘要

Liquefied natural gas (LNG) is increasingly becoming an attractive alternate forcrude oil and its usage is expected to grow tremendously in the coming years.Liquefaction of natural gas is a highly energy-intensive process. Because of itscryogenic nature, vapors called as boil-off gases (BOG) are generated at variousplaces in an LNG plant due to heat leak, vapor displacement, flashing, and hotcontact. The BOG from storage tanks, called as tankage BOG is usuallycompressed and exported to the plant fuel system. However, in some LNGplants, there exists another source of BOG; the one from intermittent loading,called as jetty BOG. As plant capacities grow and economic efficiency becomesimportant, it makes sense to integrate the jetty BOG optimally into the existingfuel gas network. We propose a novel superstructure and nonconvex mixedintegernonlinear program for addressing this problem. An industrially basedcase study showed that our approach is efficient and practically useful.