A booster system for increasing pressure of an object gas includes: a first compression unit that compresses the object gas to intermediate pressure equal to or higher than the critical pressure and lower than the target pressure and generates an intermediate supercritical fluid; a cooling unit that cools the intermediate supercritical fluid with a cooling medium and generates an intermediate supercritical pressure liquid; a liquid extracting and pressure reducing unit that extracts a part of the intermediate supercritical pressure liquid; a flow regulating valve that regulates a flow rate of the extracted part of the intermediate supercritical pressure liquid; a second compression unit that increases pressure of the rest of the intermediate supercritical pressure liquid to be equal to or higher than the target pressure; and a pressure sensor that detects pressure of the intermediate supercritical pressure liquid.

A method and apparatus for liquefying a feed gas stream comprising natural gas and carbon dioxide. A method includes compressing an input fluid stream to generate a first intermediary fluid stream; cooling the first intermediary fluid stream with a first heat exchanger to generate a second intermediary fluid stream, wherein a temperature of the second intermediary fluid stream is higher than a carbon dioxide-freezing temperature for the second intermediary fluid stream; expanding the second intermediary fluid stream to generate a third intermediary fluid stream, wherein the third intermediary fluid stream comprises solid carbon dioxide; separating the third intermediary fluid stream into a fourth intermediary fluid stream and an output fluid stream, wherein the output fluid stream comprises a liquefied natural gas (LNG) liquid; and utilizing the fourth intermediary fluid stream as a cooling fluid stream for the first heat exchanger.

The present invention relates to a cryocooler suitable for gas liquefaction applications, that comprises a coldhead (1) with one or more refrigeration stages (2, 3); further comprising: a refrigerator compressor (4) for distributing compressed gas-phase cryogen inside the coldhead (1); a heat exchanging coil (9) arranged at least partially around the external region of the coldhead (1); at least one extraction orifice (8) communicating a gas circulation circuit (5) inside the coldhead (1) with the heat exchanging coil (9); acting said extraction orifice/s (8) as pass-through port/s which allow the gas inside the coldhead (1) to flow through the inside of the heat exchanger coil (9) for exchanging heat with the exterior thereof, and wherein the heat exchanging coil (9) is adapted to connect and redirect the gas to one return port (8) connected to the gas circulation circuit (5). Another object of the invention relates to a cryogen-gas liquefaction system (11) and a method for liquefaction of gases that comprises said system (11).

An apparatus, system and method for reliquefaction of previously regasified LNG are described. A natural gas reliquefaction method includes regasifying LNG onboard a FSRU to form high pressure regasified LNG (HP RLNG), delivering the HP RLNG to a natural gas pipeline that commingles with a natural gas grid, flowing the HP RLNG through a lateral, wherein the lateral diverts HP RLNG from the natural gas pipeline to an expander prior to commingling with the natural gas grid, expanding the natural gas with the expander to obtain low pressure regasified LNG (LP RLNG), liquefying the LP RLNG in a cold box of a nitrogen expansion loop to produce low pressure LNG, and transmitting the LNG to a cryogenic cargo tank onboard an LNG tanker truck.

Closed-loop refrigeration cycles for liquid oxygen densification are disclosed. The disclosed refrigeration cycles may be turbine-based refrigeration cycles or a Joule-Thompson (JT) expansion valve based refrigeration cycles and include a refrigerant or working fluid comprising a mixture of neon or helium together with nitrogen and/or oxygen.

Closed-loop refrigeration cycles for liquid oxygen densification are disclosed. The disclosed refrigeration cycles may be turbine-based refrigeration cycles or a Joule-Thompson (JT) expansion valve based refrigeration cycles and include a refrigerant or working fluid comprising a mixture of neon or helium together with nitrogen and/or oxygen.

A method for controlling the refrigerant composition in a pre-cooled mixed refrigerant (PMR) cycle for LNG production includes obtaining a weather forecast temperature, measuring the concentration of each PMR component and measuring the ambient temperature. The method further includes calculating the optimum concentration of each PMR component for each of the measured and weather forecast temperatures and calculating the time period required to change appropriately each component concentration in transition from the ambient temperature to the weather forecast temperature; and comparing the measured and optimum concentration of each component in view of the calculated time period and direction of change in the component concentrations during the time period.

A liquefied gas treatment system according to an embodiment of the present invention includes a boil-off gas heat exchanger exchanging heat between boil-off gas, pressurized by a boil-off gas compressor and recovered along a boil-off gas supply line branching off upstream of a liquefied gas-consuming unit, and the boil-off gas supplied from a liquefied gas storage tank, wherein the boil-off gas heat exchanger cools the boil-off gas, recovered along the boil-off gas supply line, with the boil-off gas, supplied from the liquefied gas storage tank, or flash gas, supplied through a vapor recovery line.

A process for liquefying methane-rich gases comprising: (a) providing a stream of methane-rich feed gas containing higher hydrocarbons comprising C.sub.5+ hydrocarbons and/or aromatic compounds at a feed gas pressure of from 40 bar to 120 bar; (b) providing a stream of methane-rich recycle gas at a recycle gas pressure of from 40 bar to 120 bar; (c) mixing the feed gas with a first part of the recycle gas to form a mixture; (d) passing the resulting mixture to a first gas expander having an outlet, the first expander outlet having a first gas expander outlet pressure of between 3 bar and 50 bar and less than the feed gas and recycle gas pressures, to form a first gas expander outlet stream comprising a mixture of vapor and a condensed liquid containing the higher hydrocarbons; (e) separating the first gas expander outlet stream into a liquid stream and a vapor stream; (f) reheating and compressing the first vapor stream to a first vapor stream pressure of from 40 bar to 120 bar to form a first constituent of the recycle gas; (g) cooling a second part of the recycle gas to a temperature higher than an outlet temperature of the first gas expander; and, (h) liquefying said cooled second part of the recycle gas to form liquefied methane, wherein a content of C5+ hydrocarbons is about 0.1 mol % or less in the liquefied methane and a content of aromatic compounds is below 1 mol ppm in the liquefied methane.

In an embodiment, the cooled second part of the recycle gas is completely or substantially liquefied in step (h). In another embodiment, the second part of the recycle gas is liquefied to form liquefied methane and a second vapor stream in step (h), and the second vapor stream is reheated and compress in a step (i) to a second vapor stream pressure of from 40 bar to 120 bar to form a second constituent of the recycle gas.

A hydrocarbon stream, such as natural gas, is commonly cooled together with a first refrigerant stream, against an evaporating refrigerant in a series of one or more consecutively arranged common heat exchangers. The series comprises of one or more consecutively arranged common heat exchangers comprise a first common heat exchanger, upstream of which first common heat exchanger the hydrocarbon stream and the first refrigerant stream are not commonly cooled. The hydrocarbon stream to be cooled is fed into the first common heat exchanger at a hydrocarbon feeding temperature, while the first refrigerant stream is fed into the first common heat exchanger at a refrigerant feeding temperature. The temperature difference between the hydrocarbon feeding temperature and the refrigerant feeding temperature is lower than 60 C.