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.

A method and system for producing liquid air wherein liquid refrigerant is cycled between two core tanks maintained at a temperature sufficient to liquify compressed air passed through condensing tubing in the interior of the core tanks. Liquid refrigerant is cycled by alternating high pressure gas from a high pressure tank to one of the core tanks, which forces liquid refrigerant from this tank through an expansion device to expand a portion of the liquid refrigerant to absorb heat in the other core tank, the resulting refrigerant gas being driven into a low pressure tank. A compression device transfers the refrigerant gas from the low pressure tank to the high pressure tank and maintains the pressure in the high pressure tank. Connections between the low and high pressure tanks and the core tanks are reversed with each cycle.

A method and apparatus for producing liquefied natural gas. A portion of a natural gas stream is cooled in a first heat exchanger and re-combined with the natural gas stream, and heavy hydrocarbons are removed therefrom to generate a separated natural gas stream and a separator bottom stream. Liquids are separated from the separator bottom stream to form an overhead stream, which is cooled and separated to form a recycle gas stream. The recycle gas stream is compressed. A first portion of the compressed recycle gas stream is directed through the first heat exchanger and directed to the separator as a column reflux stream. The separated to natural gas stream is used as a coolant in the first heat exchanger to thereby generate a pretreated natural gas stream, which is compressed and liquefied.

A fluid cooling apparatus capable of improving liquefaction efficiency of a fluid by appropriately cooling the fluid in various temperature ranges through a simple process. The fluid cooling apparatus includes an expansion unit including a plurality of expanders, which receive refrigerants through a plurality of paths to expand the refrigerants and discharge the expanded refrigerants having different temperatures, a heat exchanger receiving the refrigerants having different temperatures from the expansion unit to cool the fluid in multistages, a precompression unit including a plurality of precompressors, which receive the refrigerants passing through the heat exchanger to compress the refrigerants and discharge the compressed refrigerants at the same pressure, a mixing tube configured to mix the refrigerants discharged from the precompression unit to supply the mixed refrigerant, and a main compression unit connected to the mixing tube to compress the mixed refrigerant and supply the compressed refrigerant to the expansion unit.

A method for producing liquefied natural gas and a stream of liquid nitrogen including step a): producing gaseous nitrogen in an air separation unit; step b): liquefying a stream of natural gas in a natural gas liquefaction unit including a main heat exchanger and a system for producing cold; step c): liquefying the nitrogen stream resulting from step a) in the main exchanger of the natural gas liquefaction unit in parallel with the liquefied natural gas in step b); wherein all the cold necessary for liquefying the stream of nitrogen and for liquefying the natural gas is supplied by the system for producing cold of the natural gas liquefaction unit.

The present invention discloses a liquid air storage device, including a storage tank, a gas circulation outlet pipe, a gas circulation inlet pipe, and a pump. An input end of the gas circulation outlet pipe communicates with the lower part of an inner cavity of the storage tank, an output end of the gas circulation outlet pipe communicates with an input end of the pump, an output end of the pump communicates with an input end of the gas circulation inlet pipe, and an output end of the gas circulation inlet pipe communicates with the upper part of the inner cavity of the storage tank. The present invention further discloses a liquid air storage method and an air liquefaction apparatus that use the foregoing liquid air storage device.

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.

An apparatus, system and method for reliquefaction of previously regasified LNG are described. A natural gas reliquefaction method includes regasifying LNG onboard a FSRU to form high pressure regasified LNG (HP RLNG), delivering the HP RLNG to a natural gas pipeline that commingles with a natural gas grid, flowing the HP RLNG through a lateral, wherein the lateral diverts HP RLNG from the natural gas pipeline to an expander prior to commingling with the natural gas grid, expanding the natural gas with the expander to obtain low pressure regasified LNG (LP RLNG), liquefying the LP RLNG in a cold box of a nitrogen expansion loop to produce low pressure LNG, and transmitting the LNG to a cryogenic cargo tank onboard an LNG tanker truck.

A liquefier device which may be a retrofit to an air separation plant or utilized as part of a new design. The flow needed for the liquefier comes from an air separation plant running in a maxim oxygen state, in a stable mode. The three gas flows are low pressure oxygen, low pressure nitrogen, and higher pressure nitrogen. All of the flows are found on the side of the main heat exchanger with a temperature of about 37 degrees Fahrenheit. All of the gasses put into the liquefier come out as a subcooled liquid, for storage or return to the air separation plant. This new liquefier does not include a front end electrical compressor, and will take a self produced liquid nitrogen, pump it up to a runnable 420 psig pressure, and with the use of turbines, condensers, flash pots, and multi pass heat exchangers. The liquefier will make liquid from a planned amount of any pure gas oxygen or nitrogen an air separation plant can produce.

Plant and process for the production of liquid methane from a feed gas stream comprising at least methane and carbon dioxide. A feed gas stream is injected into a CO.sub.2 crystallizer in countercurrent fashion against a stream of predominantly liquid methane, thereby crystallizing amounts of carbon dioxide from the feed gas stream. Gaseous methane recovered from the CO.sub.2 crystallizer is liquefied at a liquefaction exchanger.