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 for the production of liquefied natural gas from raw natural gas. The system includes a pre-treatment module to remove impurities from a raw natural gas input, a gas compression module to compress gas received from the pre-treatment module, an absorption chiller for providing gas equipment cooling in the compression module, and a gas liquefaction module including a gas pre-cooler configured to pre-cool gas received from the compression module using a closed-loop refrigeration cycle and a six-stream heat exchanger unit configured to cool gas received from the gas pre-cooler. A power module is provided that powers the pre-treatment module, gas compression module, and gas liquefaction module.

The amount of consumption of gas is reduced when the gas is expanded to be cooled by using a plurality of expansion turbines. A high-pressure expansion turbine includes: a gas supply passage through which bearing gas is supplied to a bearing portion; and a gas discharge passage through which the bearing gas which has been supplied from the gas supply passage to the bearing portion is discharged from the bearing portion. A low-pressure expansion turbine includes: a gas supply passage through which the bearing gas is supplied to a bearing portion; and a gas discharge passage through which the bearing gas which has been supplied from the gas supply passage to the bearing portion is discharged from the bearing portion. The bearing gas discharged from the gas discharge passage of the high-pressure expansion turbine is supplied to the gas supply passage of the low-pressure expansion turbine.

A system and method of using a source of low-pressure refrigerant for a cryotherapy procedure. The system may generally include a fluid reservoir and a fluid flow path in thermal exchange with the fluid reservoir, the fluid flow path including a thermal exchange device in thermal exchange with the fluid reservoir, a compressor in fluid communication with the thermal exchange device, a condenser, a reversing valve located between the compressor and the condenser, and an expansion valve located between the condenser and the thermal exchange device. The method may include transferring a low-pressure refrigerant to a first fluid reservoir, reducing the temperature of the refrigerant within the first fluid reservoir, increasing the temperature of the refrigerant within the first fluid reservoir, and transferring the pressurized refrigerant from the first fluid reservoir to a second fluid reservoir.

Provided are an apparatus and method for liquefying natural gas. The apparatus for liquefying natural gas includes a gas compressor configured to receive and compress the natural gas from a natural gas feed stream, a heat exchanging unit configured to cool a high-pressure natural gas passing through the gas compressor through heat exchange, an expansion valve configured to expand the cooled natural gas passing through the heat exchanging unit, a hold-up drum configured to phase-separate a gas-liquid mixture produced by passing through the expansion valve and divide the gas-liquid mixture into a liquefied natural gas and a cryogenic recycle gas having nitrogen content greater than that of the liquefied natural gas so as to discharge the liquefied natural gas and the cryogenic recycle gas, and a bypass line configured to provide the recycle gas discharged from the hold-up drum to the heat exchanging unit.

A system and method of using a source of low-pressure refrigerant for a cryotherapy procedure. The system may generally include a fluid reservoir and a fluid flow path in thermal exchange with the fluid reservoir, the fluid flow path including a thermal exchange device in thermal exchange with the fluid reservoir, a compressor in fluid communication with the thermal exchange device, a condenser, a reversing valve located between the compressor and the condenser, and an expansion valve located between the condenser and the thermal exchange device. The method may include transferring a low-pressure refrigerant to a first fluid reservoir, reducing the temperature of the refrigerant within the first fluid reservoir, increasing the temperature of the refrigerant within the first fluid reservoir, and transferring the pressurized refrigerant from the first fluid reservoir to a second fluid reservoir.

A gas processing system according to an embodiment of the present invention includes a heater which is configured to increase a temperature of liquefied gas compulsorily vaporized by a forcing vaporizer before the liquefied gas is joined with Boil Off Gas (BOG) compressed by a BOG compressor.

A method of liquefying natural gas. The method comprises cooling a gaseous natural gas process stream with a refrigerant flowing in a path isolated from the natural gas process stream. The refrigerant may differ in composition from a composition of the natural gas process stream, and the refrigerant composition may be selected to enhance efficiency of the refrigerant path with regard to a specific composition of the natural gas process stream. The refrigeration path may be operated at pressures, temperatures and flow rates differing from those of the natural gas process stream. Other methods of liquefying natural gas are described. A natural gas liquefaction plant is also described.

A method including, compressing a first hydrogen stream, and expanding a portion to produce a hydrogen refrigeration stream, cooling a second hydrogen stream thereby producing a cool hydrogen stream, wherein at least a portion of the refrigeration is provided by a nitrogen refrigeration stream, further cooling at least a portion of the cool hydrogen stream thereby producing a cold hydrogen stream, and a warm hydrogen refrigeration stream wherein at least a portion of the refrigeration is provided by the hydrogen refrigeration stream, compressing the warm hydrogen refrigeration stream, mixing the balance of the compressed first hydrogen stream with a high-pressure gaseous nitrogen stream to form an ammonia synthesis gas stream, and wherein the first hydrogen stream and the warm hydrogen refrigeration stream are compressed in the same compressor.

A liquefaction system for removing heat from a process fluid to condense the process fluid, the liquefaction system including a primary heat exchanger configured to remove heat from the process fluid via heat exchange with one or more refrigerants, a compressor configured to compress the one or more refrigerants, a first secondary heat exchanger configured to remove heat from the one or more refrigerants via heat exchange with ambient air, and a second secondary heat exchanger configured to remove heat from the one or more refrigerants via heat exchange with ambient water.