Embodiments relate generally to systems and methods for pre-cooling a natural gas stream to a liquefaction plant. A system may comprise a compressor configured to receive a first natural gas stream at a first pressure and produce a second natural gas stream at a second pressure; an exchanger, wherein the exchanger is configured to receive the second natural gas stream as the second pressure and cool the second natural gas stream to produce a cooled natural gas stream; and an expander, wherein the expander is configured to receive the cooled natural gas stream and expand the cooled natural gas stream from the second pressure to a third pressure.

An LNG production system including a boil off gas recondenser that can recondense boil off gas without using a BOG compressor and without depending on an LNG liquefaction process is provided.

A method for producing liquefied natural gas (LNG). A natural gas stream is transported to a liquefaction vessel. The natural gas stream is liquefied on the liquefaction vessel using at least one heat exchanger that exchanges heat between the natural gas stream and a liquid nitrogen stream to at least partially vaporize the liquefied nitrogen stream, thereby forming a warmed nitrogen gas stream and an at least partially condensed natural gas stream comprising LNG. The liquefaction vessel includes at least one tank that only stores liquid nitrogen and at least one tank that only stores LNG.

Systems and methods for transporting and managing LNG are contemplated. A source of LNG is pumped to a pressure higher than a consumer pressure, and is vaporized to provide vaporized LNG. The vaporized LNG is transported from a first location to a second location without the need for cryogenic equipment. At the second location, the vaporized LNG is expanded to the consumer pressure or a second pressure below the consumer pressure to generate refrigeration content suitable to reliquefy at least a portion of the vaporized LNG. A reliquefied natural gas is generated at the second location while providing a natural gas product to a downstream consumer at the consumer pressure.

A raw material gas liquefying device includes a feed line which feeds a raw material gas, a refrigerant circulation line which circulates a refrigerant, the refrigerant circulation line including an expansion unit of a turbine type which expands the refrigerant to generate cryogenic energy, and an expansion unit entrance valve provided at an entrance side of the expansion unit, a heat exchanger which exchanges heat between the raw material gas and the refrigerant, a cooler which performs initial cooling of the raw material gas and the refrigerant by heat exchange with liquid nitrogen, and a controller which manipulates the opening rate of the expansion unit entrance value and performs a feedback control so that the rotation speed of the expansion unit reaches a predetermined target value, and outputs the opening rate command to the expansion unit entrance valve, at start-up and stop of the expansion unit.

A refrigerant cycle pressure control system includes: a heat exchanger cooling boil-off gas received from a storage tank; a refrigerant cycle including a refrigerant circulation line, a refrigerant compressor, and an expander; an inventory tank storing the refrigerant to be charged to the refrigerant cycle; a refrigerant supply line connecting the inventory tank to an upstream side of the refrigerant compressor to replenish the refrigerant cycle with the refrigerant; a refrigerant discharge line connecting a downstream side of the refrigerant compressor to the inventory tank to discharge the refrigerant from the refrigerant cycle to the inventory tank; and a pressure regulation line branched off of the refrigerant discharge line. The refrigerant cycle is depressurized by discharging the refrigerant from the refrigerant cycle through the refrigerant discharge line or the pressure regulation line.

A method and apparatus for liquefying a feed gas stream comprising natural gas and carbon dioxide. A method includes compressing an input fluid stream to generate a first intermediary fluid stream; cooling the first intermediary fluid stream with a first heat exchanger to generate a second intermediary fluid stream, wherein a temperature of the second intermediary fluid stream is higher than a carbon dioxide-freezing temperature for the second intermediary fluid stream; expanding the second intermediary fluid stream to generate a third intermediary fluid stream, wherein the third intermediary fluid stream comprises solid carbon dioxide; separating the third intermediary fluid stream into a fourth intermediary fluid stream and an output fluid stream, wherein the output fluid stream comprises a liquefied natural gas (LNG) liquid; and utilizing the fourth intermediary fluid stream as a cooling fluid stream for the first heat exchanger.

In an aspect, a system comprises a water stream in fluid communication with an electrolyzer; the electrolyzer comprising an anode and a cathode side chamber; a deep space oxygen radiator in fluid communication with the anode side chamber of the electrolyzer; a cryogenic heat exchanger comprising an oxygen storage tank in fluid communication with the deep space oxygen radiator; an electrochemical hydrogen compressor in fluid communication with the cathode side chamber; a hydrogen storage tank in fluid communication with the electrochemical hydrogen compressor via a cooled hydrogen stream; wherein at least a portion of the cooled hydrogen stream is in a first fluid communication with an expansion valve and the cryogenic heat exchanger; wherein the hydrogen storage tank is in a second fluid communication with the electrochemical hydrogen compressor via a warmed hydrogen stream; and wherein the cryogenic heat exchanger is in fluid communication with the warmed hydrogen stream.

Described herein are methods and systems for the liquefaction of a natural gas stream using a refrigerant comprising methane or a mixture of methane and nitrogen. The methods and systems use a refrigeration circuit and cycle that employs one or more turbo-expanders to expand one or more streams of gaseous refrigerant to provide one or more streams of at least predominantly gaseous refrigerant that are used to provide refrigeration for liquefying and/or precooling the natural gas, and a J-T valve to expand down to a lower pressure a stream of liquid or two-phase refrigerant to provide a vaporizing stream of refrigerant that provides refrigeration for sub-cooling.

Described herein are methods and systems for the liquefaction of a natural gas feed stream using a refrigerant comprising methane. The methods and systems use a refrigeration circuit and cycle that employs two or more turbo-expanders to expand two or more streams of gaseous refrigerant down to different pressures to provide cold streams of at least predominantly gaseous refrigerant at different pressures that are used to provide refrigeration for precooling and liquefying the natural gas. The resulting liquefied natural gas stream is then flashed to produce an LNG product and a flash gas, the flash gas being recycled to the natural gas feed stream.