Disclosed techniques include controlled liquefaction and energy management. A gas within a first pressure containment vessel is pressurized using a column of liquid. The gas that is being pressurized is cooled using a liquid spray, wherein the liquid spray is introduced into the first pressure containment vessel in a region occupied by the gas. The liquid spray keeps the pressurizing to be isothermal. The gas that was pressurized is metered into a second pressure containment vessel, wherein the metering enables liquefaction of the gas. The gas that was pressurized is stored in a gas capacitor prior to the metering. The gas that was liquefied in the second pressure containment vessel is pushed into a holding tank, wherein the holding tank stores a liquefied state of the gas, and wherein the pushing is accomplished by the pressure of the gas that was metered into the second pressure containment vessel.

A liquid natural gas (LNG) reforming system of the present invention may include a reformer provided to receive LNG from an LNG tank; a C02 PSA unit connected to the reformer and configured to extract carbon dioxide from off-gas generated from the reformer; a cooler connected to the C02 PSA unit and configured to cool and liquefy the carbon dioxide extracted by the C0.sub.2 PSA unit using the LNG supplied from the LNG tank to the reformer; a storage tank connected to the cooler and provided to store liquid carbon dioxide of the cooler therein; and a circulation pump provided to pump the liquid carbon dioxide from the cooler into the storage tank and circulate a part of the liquid carbon oxide into the cooler.

A cooling system includes a compressor configured to pressurize carbon dioxide to form pressurized carbon dioxide, a mixer configured to generate mixed refrigerant in which the pressurized carbon dioxide and solvent in a liquid state, a depressurization apparatus provided downstream from the mixer and configured to depressurize the mixed refrigerant, a separator configured to separate carbon dioxide in a gas state from the mixed refrigerant, a heat exchanger configured to exchange heat between the mixed refrigerant cooled through depressurization and a fluid to be cooled, and a second heat exchanger configured to cool the carbon dioxide or the mixed refrigerant using vaporized carbon dioxide or the mixed refrigerant.

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 cooling system includes a compressor configured to pressurize carbon dioxide to form pressurized carbon dioxide, a mixer configured to generate mixed refrigerant in which the pressurized carbon dioxide and solvent in a liquid state, a depressurization apparatus provided downstream from the mixer and configured to depressurize the mixed refrigerant, a separator configured to separate carbon dioxide in a gas state from the mixed refrigerant, a heat exchanger configured to exchange heat between the mixed refrigerant cooled through depressurization and a fluid to be cooled, and a second heat exchanger configured to cool the carbon dioxide or the mixed refrigerant using vaporized carbon dioxide or the mixed refrigerant.

A process for liquefying a natural gas comprising a mixture of hydrocarbons predominating in methane, the process comprising a first semi-open refrigerant cycle with natural gas in which any natural gas liquids that have condensed are separated from the natural gas feed stream, which stream then passes through a main cryogenic heat exchanger (4) in order to contribute by heat exchange to pre-cooling a main natural gas stream (F-P) and to cooling an initial refrigerant gas stream (G-0), a second semi-open refrigerant cycle with natural gas for contributing to pre-cooling the natural gas and the refrigerant and also to liquefying the natural gas, and a closed refrigerant cycle with refrigerant gas for subcooling the liquefied natural gas and for delivering refrigeration power in addition to the other two cycles. The invention also provides a natural gas liquefaction installation for performing such a process.

A method for liquefying ammonia can include the steps of: providing a pressurized carbon dioxide stream from a power generating facility; expanding the pressurized carbon dioxide stream to a lower pressure that is sufficient to produce a dual phase carbon dioxide fluid; introducing the dual phase carbon dioxide fluid to a gas-liquid separator; withdrawing a liquid stream from the gas-liquid separator; and liquefying an ammonia gas stream in an ammonia liquefier by indirect contact with the liquid stream from the gas-liquid separator, thereby forming a liquid ammonia stream and a gaseous carbon dioxide stream.

The invention relates to a method for condensing a gas, wherein the gas is subjected to cooling in indirect heat exchange with a refrigerant and at least part of the refrigerant is subjected, after the heat exchange with the gas, to compression by means of a drive (GT1) that produces waste heat and to a partial or complete condensing process. After the partial or complete condensing process, a first portion of the refrigerant is subjected to the heat exchange with the gas and a second portion of the refrigerant is subjected, in succession, to pressurization, heating by means of the waste heat of the drive (GT1) and work-performing expansion and thereafter is fed back to the partial or complete condensing process. The invention further relates to a corresponding system.

The present invention relates to a refrigerant composition. According to the invention it is envisioned that the composition comprises comprising an inert gas selected from nitrogen, argon, neon and a mixture thereof, and a mixture of at least two C.sub.1-C.sub.5 hydrocarbons. The present invention further relates to the use of the refrigerant composition in a method for liquefying a gaseous substance, particularly hydrogen or helium.

The systems and methods described herein integrate a supercritical fluid power generation system with a LNG production/NGL separation system. A heat exchanger thermally couples the supercritical fluid power generation system with the LNG production/NGL separation system. A relatively cool heat transfer medium, such as carbon dioxide, passes through the heat exchanger and cools a first portion of extracted natural gas. The relatively warm heat transfer medium returns to the supercritical fluid power generation system where a compressor and a thermal input device, such as a combustor, are used to increase the pressure and temperature of the heat transfer medium above its critical point to provide a supercritical heat transfer medium. A second portion of the extracted natural gas may be used as fuel for the thermal input device.