A system for reliquefying a boil off gas generated in a storage tank includes a first compressor compressing a partial amount (hereinafter, referred to as fluid a) of boil off gas discharged from the storage tank, a second compressor compressing another partial amount (hereinafter, referred to as fluid b) of boil off gas discharged from the storage tank, a second expanding unit expanding a partial amount (hereinafter, referred to as fluid c) of a flow formed as the fluid a and the fluid b join, a heat-exchanger cooling another partial amount (hereinafter, referred to as fluid d) of the flow formed as the fluid a and the fluid b join, and a first expanding unit expanding the fluid d cooled by the heat-exchanger, wherein the heat-exchanger heat-exchanges the fluid d with the fluid c as a coolant expanded by the second expanding unit to cool the fluid d.

Cryogenic energy storage systems, and particularly methods for capturing cold energy and re-using that captured cold energy, are disclosed. The systems allow cold thermal energy from the power recovery process of a cryogenic energy storage system to be captured effectively, to be stored, and to be effectively utilised. The captured cold energy could be reused in any co-located process, for example to enhance the efficiency of production of the cryogen, to enhance the efficiency of production of liquid natural gas, and/or to provide refrigeration. The systems are such that the cold energy can be stored at very low pressures, cold energy can be recovered from various components of the system, and/or cold energy can be stored in more than one thermal store.

Systems and processes for natural gas processing, liquefaction, and storage are described. The systems and processes include one or more arrangements of features which are capable of liquefying all of the gas entering an inlet of the system or a portion of the entering gas. The portion of the entering gas that is liquefied can vary based on the pressure of an outlet of the system, which can be fixed or vary based on usage downstream.

A method for electrical energy storage with co-production of liquefied methaneous gas which comprises in combination the processes of charging the storage with liquid air through its production using an externally powered compressor train and open air auto-refrigeration cycle, storing the produced liquid air and discharging the storage through pumping, regasifying, superheating and expanding the stored air with production of on-demand power, and additionally includes a process of recovering the cold thermal energy released by regasified liquid air for controlled liquefying the methaneous gas delivered into energy storage facility at a rate and pressure consistent with those of liquid air.

Cryogenic energy storage systems, and particularly methods for capturing cold energy and re-using that captured cold energy, are disclosed. The systems allow cold thermal energy from the power recovery process of a cryogenic energy storage system to be captured effectively, to be stored, and to be effectively utilized. The captured cold energy could be reused in any co-located process, for example to enhance the efficiency of production of the cryogen, to enhance the efficiency of production of liquid natural gas, and/or to provide refrigeration. The systems are such that the cold energy can be stored at very low pressures, cold energy can be recovered from various components of the system, and/or cold energy can be stored in more than one thermal store.

Described herein is a method and system for liquefying a natural gas feed stream to produce an LNG product. The natural gas feed stream is liquefied, by indirect heat exchange with a gaseous methane or natural gas refrigerant circulating in a gaseous expander cycle, to produce a first LNG stream. The first LNG stream is expanded, and the resulting vapor and liquid phases are separated to produce a first flash gas stream and a second LNG stream. The second LNG stream is then expanded, with the resulting vapor and liquid phases being separated to produce the second flash gas stream and a third LNG stream, all or a portion of which forms the LNG product. Refrigeration is recovered from the second flash gas by using said stream to sub-cool the second LNG stream or a supplementary LNG stream.

A method of supplying refrigeration to air separation plants within an air separation plant facility in which a refrigerant stream is produced at cryogenic temperature within a centralized refrigeration system. Streams of the refrigerant at the cryogenic temperature are introduced into the air separation plants such that all or a part of the refrigeration requirements of the air separation plants are supplied by the streams of the refrigerant.

A method of supplying refrigeration to air separation plants within an air separation plant facility in which a refrigerant stream is produced at cryogenic temperature within a centralized refrigeration system. Streams of the refrigerant at the cryogenic temperature are introduced into the air separation plants such that all or a part of the refrigeration requirements of the air separation plants are supplied by the streams of the refrigerant.

A method of producing liquefied natural gas (LNG) is disclosed. A natural gas stream is provided from a supply of natural gas. The natural gas stream is compressed in at least two serially arranged compressors to a pressure of at least 2,000 psia to form a compressed natural gas stream. The compressed natural gas stream is cooled to form a cooled compressed natural gas stream. The cooled compressed natural gas stream is expanded in at least one work producing natural gas expander to a pressure that is less than 3,000 psia and no greater than the pressure to which the at least two serially arranged compressors compress the natural gas stream, to thereby form a chilled natural gas stream. The chilled natural gas stream is liquefied.

The invention relates to a method and an installation for producing liquid helium, said installation comprising a cooling/liquefaction device comprising a working circuit that subjects a helium-enriched working fluid to a thermodynamic cycle in order to produce liquid helium, said circuit comprising at least one working fluid compression body and a plurality of heat exchangers. The installation also comprises a plurality of fluid recovery lines having respective upstream ends to be selectively connected to respective reservoirs, and a first collection line having an upstream end connected to the recovery lines and a downstream end connected to a receiving body that can supply the working circuit with a working fluid. The installation is characterized in that it comprises at least one second and one third collection line that each have an upstream end connected to the recovery lines and a downstream end connected to the working circuit, the upstream ends of the second and third collection lines being connected at separate determined positions of the working circuit, that respectively correspond to separate temperature levels of the working fluid in the working circuit.