An LNG plant comprises a cold box and a refrigeration unit fluidly coupled with a plurality of heat exchanger passes in the cold box. The refrigeration unit is configured to provide a first refrigerant stream to a first heat exchanger pass of the plurality of heat exchanger passes at a first pressure, a second refrigerant stream to a second heat exchanger pass at a second pressure, and a third refrigerant stream to a third heat exchanger pass at a third pressure. The second refrigerant stream comprises a first portion of the first refrigerant stream, and the third refrigerant stream comprises a second portion of the first refrigerant stream. The second pressure and the third pressure are both below the first pressure. The cold box is configured to produce LNG from a natural gas feed stream to the cold box using a refrigeration content from the refrigeration unit.

Liquefier arrangements configured for flexible co-production of both liquid natural gas (LNG) and liquid nitrogen (LIN) are provided. Each liquefier arrangement comprises separate and independent nitrogen recycle circuits or loops, including a warm recycle circuit and a cold recycle circuit with a means for diverting nitrogen refrigerant between the two recycle circuits or loops. The warm recycle circuit includes a booster loaded warm turbine, a warm booster compressor and warm recycle compression whereas the cold recycle circuit includes a booster loaded cold turbine, a cold booster compressor and a separate cold recycle compression.

The process comprises the following steps: mixing a gaseous stream of flash gas and a gaseous stream of boil-off gas to form a mixed gaseous flow; compressing the mixed gaseous flow in at least one compression apparatus to form a flow of compressed combustible gas; withdrawing a bypass flow in the flow of compressed combustible gas; compressing the bypass flow in at least one downstream compressor; cooling and expanding the compressed bypass flow; reheating at least a first stream derived from the expanded bypass flow in at least one downstream heat exchanger, reintroducing the first reheated stream in the mixed gaseous flow upstream from the compression apparatus.

A technology liquefies natural gas. The natural gas liquefaction method pre-cools treated natural gas by ethane evaporation, sub-cools liquefied gas using cooled nitrogen as a refrigerant, reduces liquefied gas pressure, separates non-liquefied gas and diverts liquefied natural gas. Before pre-cooling the natural gas is compressed, ethane is evaporated during the multi-stage pre-cooling of liquefied gas with simultaneous evaporation of ethane using cooled ethane as a refrigerant. Ethane generated by evaporation is compressed, condensed and used as a refrigerant during the cooling of liquefied gas and nitrogen, with nitrogen being compressed, cooled, expanded and fed to the natural gas sub-cooling stage. The natural gas liquefaction unit contains a natural gas liquefaction circuit, an ethane circuit and a nitrogen circuit. The natural gas liquefaction circuit includes a natural gas compressor, a cooler unit, ethane vaporizers, a closed-end subcooling heat exchanger, and a separator, connected in series.

A method for producing an LNG from natural gas, comprising liquefaction of at least a first part of the natural gas in a first heat exchanger by heat exchange with a first mixed refrigerant fluid in a closed cycle, sub-cooling of liquefied natural gas in a second heat exchanger by heat exchange with a second refrigerant fluid of a second refrigeration cycle, expansion of the sub-cooled liquefied natural gas stream and admission into a flash gas separator, withdrawal of liquefied natural gas at the bottom of the separator, and withdrawal, at the head, of a gas flow, and supply of the second refrigeration cycle by at least a part of said gas flow.

The present invention relates to a method for liquefying hydrogen, the method comprises the steps of: cooling a feed gas stream comprising hydrogen with a pressure of at least 15 bar(a) to a temperature below the critical temperature of hydrogen in a first cooling step yielding a liquid product stream. According to the invention, the feed gas stream is cooled by a closed first cooling cycle with a high pressure first refrigerant stream comprising hydrogen, wherein the high pressure first refrigerant stream is separated into at least two partial streams, a first partial stream is expanded to low pressure, thereby producing cold to cool the precooled feed gas below the critical pressure of hydrogen, and compressed to a medium pressure, and wherein a second partial stream is expanded at least close to the medium pressure and guided into the medium pressure first partial stream.

The system for treating a gas deriving from the evaporation of a cryogenic liquid and supplying pressurized gas to a gas engine according to the invention comprises, on the one hand, from upstream to downstream, a reliquefaction unit (10) with compression means (11, 12, 13), a first heat exchanger (17) and expansion means (30), and, on the other hand, a pressurized gas supply line comprising, from upstream to downstream, a pump (48) for pressurizing the liquid and high-pressure vaporization means (61). The pressurized gas supply line has, upstream of the vaporization means (61), a bypass (57) for supplying a second heat exchanger (60) between, on the one hand, pressurized liquid of the supply line (56) and, on the other hand, a line (22) of the reliquefaction unit (10) downstream of the first exchanger and upstream of the expansion means (30).

The system comprises: a main driver configured for rotating at a substantially constant rotational speed; a rotating load configured to be driven into rotation by the main driver; a controller, for controllably adjusting a load rotational speed; a variable speed transmission, arranged between the main driver and the load and comprised of a speed summing gear arrangement having a first input shaft, a second input shaft and an output shaft; an auxiliary driver, mechanically coupled to the second input shaft of the speed summing gear arrangement. The first input shaft of the speed summing gear arrangement is drivingly coupled to the main driver. The output shaft of the speed summing gear arrangement is drivingly coupled to the rotating load. The speed of the output shaft is a combination of a speed of the main driver and of a speed of the auxiliary driver.

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 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.