A gas recovery system separates a mixed gas including a process gas and an inert gas. The gas recovery system includes a cooling section for cooling and liquefying the process gas contained in the mixed gas by cooling the mixed gas at a temperature higher than a condensation temperature of the inert gas and lower than a condensation temperature of the process gas, a separating section for separating the cooled mixed gas into the process gas in a liquid state and the inert gas in a gas state, and a process gas recovery line that is connected to the separating section which circulates and gasifies the liquid-state process gas and then supplies the process gas into the a compressor. The mixed gas is formed by mixing the process gas, which is compressed by the compressor, and the inert gas, which is supplied to a seal portion of the compressor.

The present invention relates to a floating LNG plant (1, 1, 100) comprising a converted LNG carrier with a hull and a plurality of LNG storage tanks (4, 104) wherein in that the floating LNG plant (1, 1, 100) comprises: at least one sponson (2, 2, 3, 3, 102, 103) on the side of the hull, for creating additional hull volume, process equipment (110) for LNG processing on the floating LNG plant (1, 1, 100), anda reservoir for storing fluids separated during the LNG processing, wherein said reservoir is formed by the ballast tank or in the space reserved for the ballast tank of the original LNG carrier.

System and methods for floating dockside liquefaction of natural gas are described. A system for floating dockside liquefaction of natural gas comprises a natural gas pretreatment facility located onshore proximate a dock, wherein the natural gas pretreatment facility is configured to process pipeline quality gas into pretreated natural gas, a floating liquefaction unit moored at the dock, wherein the floating liquefaction unit further comprises a natural gas liquefaction module on a deck, and an LNG storage tank for storing produced LNG below the deck, a pipeline coupling the onshore pretreatment facility to the dock, wherein the pipeline is configured to transport pretreated natural gas onto the dock, and a high pressure gas arm fluidly coupling the pipeline to the floating liquefaction unit, wherein the gas arm is configured to transfer pretreated natural gas to the floating liquefaction unit.

Described herein are apparatuses and systems related to at-shore liquefaction of natural gas. The at-shore water-based apparatuses can include a hull, an air-cooled electrically-driven refrigeration system (AER System), and a plurality of liquefied natural gas (LNG) storage tanks that are on a lower deck of the hull. The AER System can be supported by a plurality of support structures extending through an upper deck of the hull.

Described herein are apparatuses and systems related to at-shore liquefaction of natural gas. The at-shore water-based apparatuses can include a hull, an air-cooled electrically-driven refrigeration system (AER System), a plurality of liquefied natural gas (LNG) storage tanks that are on a lower deck of the hull, and a closed loop ballast system. The closed loop ballast system can include a ballast fluid to assist in stabilizing the water-based apparatus moored to an at-shore location without discharging the ballast fluid to water proximate the at-shore location. Systems including an at-shore water-based apparatus can also include a land-based source of electricity and a land-based source of feed gas.

A pretreatment system and method for a floating liquid natural gas (FLNG) facility are presented. The inlet natural gas stream flows through a membrane system to remove carbon dioxide and a heat exchanger, producing first and second cooled CO.sub.2-depleted non-permeate streams. The first cooled CO.sub.2-depleted non-permeate stream is routed to additional pretreatment equipment, while the second cooled CO.sub.2-depleted non-permeate stream is routed directly to a LNG train. Alternatively, the inlet natural gas stream may flow through a membrane system to produce a single cooled CO.sub.2-depleted non-permeate stream that is routed to the LNG train after sweetening and dehydration. Because the pretreatment system delivers the incoming gas stream to the LNG train at a lower temperature than conventional systems, less energy is needed to convert the gas stream to LNG. In addition, the pretreatment system has a smaller footprint than conventional pretreatment systems.

A pretreatment system and method for a floating liquid natural gas (FLNG) facility are presented. The inlet natural gas stream flows through a membrane system to remove carbon dioxide and a heat exchanger, producing first and second cooled CO.sub.2-depleted non-permeate streams. The first cooled CO.sub.2-depleted non-permeate stream is routed to additional pretreatment equipment, while the second cooled CO.sub.2-depleted non-permeate stream is routed directly to a LNG train. Alternatively, the inlet natural gas stream may flow through a membrane system to produce a single cooled CO.sub.2-depleted non-permeate stream that is routed to the LNG train after sweetening and dehydration. Because the pretreatment system delivers the incoming gas stream to the LNG train at a lower temperature than conventional systems, less energy is needed to convert the gas stream to LNG. In addition, the pretreatment system has a smaller footprint than conventional pretreatment systems.

A method and apparatus for cooling and liquefying a hydrocarbon stream using a liquefaction process wherein a hydrocarbon stream is cooled and at least partially liquefied to obtain a liquefied hydrocarbon stream. In the method, one or more compressors are driven with one or more electric drivers, that are powered with one or more dual-fuel diesel-electric generators. These dual-fuel diesel-electric generations are operated by passing one or more hydrocarbon fuel streams to the one or more dual-fuel diesel-electric generators, wherein at least one of the one or more hydrocarbon fuel streams comprises a stream that is generated in the liquefaction process. The apparatus may be provided on a floating structure, a caisson, or off-shore platform.

Embodiments of the present invention provide a process for liquefaction of a natural gas. The process includes cooling the natural gas with a first refrigerant provided by a first cooling system and cooling the natural gas with a second refrigerant provided by a second cooling system. The second cooling system is a single phase cooling system. The first and second cooling systems operate independently from each other. The second refrigerant is cooled with the first refrigerant so that the cooling capacity of the second refrigerant and the second cooling system is increased.

Described herein is a method and system for liquefying a natural gas feed stream to produce an LNG product. The natural gas feed stream is liquefied, by indirect heat exchange with a gaseous methane or natural gas refrigerant circulating in a gaseous expander cycle, to produce a first LNG stream. The first LNG stream is expanded, and the resulting vapor and liquid phases are separated to produce a first flash gas stream and a second LNG stream. The second LNG stream is then expanded, with the resulting vapor and liquid phases being separated to produce the second flash gas stream and a third LNG stream, all or a portion of which forms the LNG product. Refrigeration is recovered from the second flash gas by using said stream to sub-cool the second LNG stream or a supplementary LNG stream.