A system for cooling a gas includes a pre-cool heat exchanger and a liquefaction heat exchanger. The pre-cool heat exchanger uses a pre-cool refrigerant to pre-cool a feed gas stream prior to the stream being directed to a liquefaction heat exchanger. The liquefaction heat exchanger uses a mixed refrigerant to further cool the pre-cooled gas. The pre-cool heat exchanger also pre-cools the liquefaction mixed refrigerant used by the liquefaction heat exchanger.

The device (400) for liquefying a natural gas comprises: a compressor (105) of a first vaporized coolant chemical mixture, a means (110) for fractionating the compressed mixture into a heavy fraction and a light fraction, a first body (115) for exchanging heat between the heavy fraction of the first mixture and the natural gas to cool at least the natural gas, a second body (120) for exchanging heat between the light fraction of the first mixture and the natural gas cooled in the first exchange body to liquefy the natural gas, a conduit (125) for returning the first vaporized coolant mixture in the heat exchange bodies to the compressor, a regulator (405) for the liquefied natural gas, a collector (410) for the evaporation gas produced during the expansion of the gas in the regulator, a conduit (415) for injecting the evaporation gas at the inlet of the second exchange body, upstream of an inlet (116) for the natural gas in the first exchange body (115), a third body (420) for exchanging heat between the natural gas and a second chemical coolant compound, a means (425) for compressing the second vaporized compound, a means (430) for cooling the second compressed compound and a conduit (435) for transferring the second cooled compound towards the third exchange body.

The device (100) for liquefying a natural gas comprises: a compressor (105) for a first vaporized coolant chemical mixture, a means (110) for fractionating the compressed mixture into a heavy fraction and a light fraction, a first heat exchange body (115) for heat exchange between the heavy fraction of the first mixture and the natural gas in order to cool at least the natural gas, a second heat exchange body (120) for heat exchange between the light fraction of the first mixture and the cooled natural gas in the first exchange body in order to liquefy the natural gas, and a return pipe (125) for return of the first vaporized coolant mixture in the heat exchange body to the compressor (105), upstream from an inlet (116) for the natural gas in the first exchange body (115) or downstream from an outlet (121) of liquefied natural gas from the second exchange body (120), a third heat exchange body (130, 135) for heat exchange between the natural gas and a second coolant chemical compound, and a means (140, 145) for compressing the second vaporized compound.

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.

A system and method for increasing the efficiency of natural gas liquefaction processes by using a hybrid cooling system and method. More specifically, a system and method for converting a transcritical precooling refrigeration process to a subcritical process. In one embodiment, the refrigerant is cooled to sub-critical temperature using an economizer. In another embodiment, the refrigerant is cooled to a sub-critical temperature using an auxiliary heat exchanger. Optionally, the economizer or auxiliary heat exchanger can be bypassed when ambient temperatures are sufficiently low to cool the refrigerant to a sub-critical temperature. In another embodiment, the refrigerant is isentropically expanded.

A system and method for increasing the efficiency of natural gas liquefaction processes by using a hybrid cooling system and method. More specifically, a system and method for converting a transcritical precooling refrigeration process to a subcritical process. In one embodiment, the refrigerant is cooled to sub-critical temperature using an economizer. In another embodiment, the refrigerant is cooled to a sub-critical temperature using an auxiliary heat exchanger. Optionally, the economizer or auxiliary heat exchanger can be bypassed when ambient temperatures are sufficiently low to cool the refrigerant to a sub-critical temperature. In another embodiment, the refrigerant is isentropically expanded.

The device (100) for pre-cooling a flow (101) of a target gas to a temperature of less than or equal to 90 K comprises: a group (105) of at least two heat exchangers (106, 107, 108, 136) for exchanging heat between the target gas flow, a flow (102) of a first cooling fluid and at least one flow among a flow of a second cooling fluid and a flow of a third cooling fluid, closed circulation circuit (110) for a flow of a second cooling fluid, said fluid comprising at least methane, said circuit comprising: at least one compression stage (111, 112), at least one liquid-gas separation stage (115, 116) and at least one expansion stage (120, 121, 122) and a circulation circuit (125) for a flow of the third cooling fluid through at least one of said heat exchangers.

A method and system for liquefying a methane-rich high-pressure feed gas stream using a system having first and second heat exchanger zones and a compressed refrigerant stream. The compressed refrigerant stream is cooled and directed to the second heat exchanger zone to additionally cool it below ambient temperature. It is then expanded and passed through the first heat exchanger zone such that it has a temperature that is cooler, by at least 5 F., than the highest fluid temperature within the first heat exchanger zone. The feed gas stream is passed through the first heat exchanger zone to cool at least part of it by indirect heat exchange with the refrigerant stream, thereby forming a liquefied gas stream. At least a portion of the first warm refrigerant stream is directed to the second heat exchanger zone to cool the refrigerant stream, which is compressed.

A method and system for liquefying a methane-rich high-pressure feed gas stream using a first heat exchanger zone and a second heat exchanger zone. The feed gas stream is mixed with a refrigerant stream to form a second gas stream, which is compressed, cooled, and directed to a second heat exchanger zone to be additionally cooled below ambient temperature. It is then expanded to a pressure less than 2,000 psia and no greater than the pressure to which the second gas stream was compressed, and then separated into a first expanded refrigerant stream and a chilled gas stream. The first expanded refrigerant stream is expanded and then passed through the first heat exchanger zone such that it has a temperature that is cooler, by at least 5 F., than the highest fluid temperature within the first heat exchanger zone.

A system and method for the production and supply of a densified, liquid oxidant to a space vehicle launch facility with one or more launch platforms is provided. A low pressure gaseous oxygen stream is piped from a nearby air separation unit and is then liquefied and densified in a two-stage, integrated liquefaction/densification system. The first refrigeration stage is a nitrogen based reverse Brayton cycle refrigeration cycle, that liquefies the gaseous oxygen and subcools the resulting liquid oxygen to a temperature of about 81 Kelvin. The second refrigeration stage is a mixed refrigerant loop containing some combination of helium and/or neon refrigerants that densifies the liquid oxygen to a temperature of about 57 Kelvin. The integrated liquefaction and densification system may also be configured to densify liquid methane or other propellants used in space vehicle launches.