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.

A system and method for producing liquefied natural gas from a natural gas source is provided. The method may include feeding natural gas provided by the natural gas source to a liquefaction module. The method may also include flowing the natural gas through a product stream of the liquefaction module. The method may further include flowing a process fluid through a liquefaction stream of the liquefaction module to cool at least a portion of the natural gas flowing through the product stream to produce the liquefied natural gas.

A process for liquefying a natural gas comprising a mixture of hydrocarbons predominating in methane, the process comprising a first semi-open refrigerant cycle with natural gas in which any natural gas liquids that have condensed are separated from the natural gas feed stream, which stream then passes through a main cryogenic heat exchanger (4) in order to contribute by heat exchange to pre-cooling a main natural gas stream (F-P) and to cooling an initial refrigerant gas stream (G-0), a second semi-open refrigerant cycle with natural gas for contributing to pre-cooling the natural gas and the refrigerant and also to liquefying the natural gas, and a closed refrigerant cycle with refrigerant gas for subcooling the liquefied natural gas and for delivering refrigeration power in addition to the other two cycles. The invention also provides a natural gas liquefaction installation for performing such a process.

A refrigerator according to the present invention includes: a cooling part for cooling an object to be cooled through heat exchange with a refrigerant; an expander-integrated compressor including a compressor for compressing the refrigerant and an expander for expanding the refrigerant integrated therein; and a refrigerant circulation line configured to circulate the refrigerant through the compressor, the expander, and the cooling part. The compressor includes a low-stage compressor, a middle-stage compressor, and a high-stage compressor disposed in series in the refrigerant circulation line. The expander-integrated compressor includes: the middle-stage compressor; an expander for adiabatically expanding and cooling the refrigerant discharged from the high-stage compressor; a first motor having an output shaft connected to the middle-stage compressor and to the expander; at least one non-contact type bearing, disposed between the middle-stage compressor and the expander, for supporting the output shaft of the first motor without being in contact with the output shaft; and a casing for housing the middle-stage compressor, the expander, and the at least one non-contact type bearing.

A ship includes: a boil-off gas heat exchanger which heat-exchanges a compressed boil-off gas (a first fluid) by means of a boil-off gas discharged from the storage tank as a refrigerant; a compressor installed on the downstream of the boil-off gas heat exchanger and compressing a part of the boil-off gas discharged from the storage tank; first and second extra compressors provided in parallel with the compressor on the downstream of the boil-off gas heat exchanger and compressing the other part of the boil-off gas discharged from the storage tank; a refrigerant heat exchanger which additionally cools the first fluid cooled by means of the boil-off gas heat exchanger; a refrigerant decompressing device which expands a second fluid, which has been sent to the refrigerant heat exchanger and cooled by means of the refrigerant heat exchanger, and then sending the expanded second fluid back to the refrigerant heat exchanger.

An integrated method for the production of liquefied natural gas (LNG) and syngas is provided. The method can include the steps of: utilizing letdown energy of a high pressure natural gas stream that is withdrawn from a natural gas pipeline to provide a warm temperature cooling; utilizing a refrigeration cycle to provide a cold temperature cooling, wherein the refrigeration cycle comprises a refrigerant recycle compressor that is powered utilizing a steam turbine; and cooling a second high pressure natural gas stream using the warm temperature cooling and the cold temperature cooling to produce an LNG product stream. The second high pressure natural gas stream is withdrawn from the natural gas pipeline, and the steam turbine is powered by high pressure steam that is produced from a syngas production facility.

The invention primarily concerns a facility for storing and cooling a liquefied gas, for example a liquefied natural gas, the facility comprising at least one tank configured to contain the liquefied gas, a closed cooling circuit configured to be supplied with liquefied gas in the liquid state coming from the tank, at least one injection member configured for reinjecting cooled liquefied gas into the tank, the facility being characterized in that it comprises at least one connection line configured to recover a cooled gas from at least one remote container that is separate and independent from the facility.

An exemplary embodiment of the present techniques provides a system for decreasing a temperature of a fluid. The system includes an axial flow expander for expanding gas flowed in a direction along an axis thereof. The axial flow expander includes: an outer casing made as a unified structure having an inlet port and an outlet port. An inner casing is fixed inside the outer casing. A rotor shaft is accommodated inside the inner casing, and is aligned with the axis. A number of bearings allow the rotor shaft to rotate around the axis. Moving blades protrude from the rotor shaft and are arranged inside the gas passage in an alternating fashion with a number of stator vanes. The inner casing, the rotor shaft, the bearings, the stator vanes, and the moving blades are integrally assembled, and inserted into the outer casing in the direction along the axis.

Disclosed is a device for liquefying a fluid, comprising a fluid circuit to be cooled, the device comprising a heat exchanger assembly in heat exchange with the fluid circuit to be cooled, at least one first cooling system in heat exchange with at least a portion of the heat exchanger assembly, the first cooling system being a refrigerator having a cycle for refrigerating a cycle gas mainly comprising helium, said refrigerator comprising in series in a cycle circuit: a mechanism for compressing the cycle gas, at least one member for cooling the cycle gas, a mechanism for expanding the cycle gas, and at least one member for reheating the expanded cycle gas, wherein the compression mechanism includes at least four compression stages in series composed of a centrifugal compressor assembly, the compression stages being mounted on shafts that are rotationally driven by a motor assembly, the expansion mechanism comprising at least three expansion stages in series composed of a set of centripetal turbines, the at least one member for cooling the cycle gas being configured to cool the cycle gas at the outlet of at least one of the turbines, and wherein at least one of the turbines is coupled to the same shaft as at least one compression stage so as to feed the mechanical work produced during the expansion to the compression stage.