A method for liquefying a hydrocarbon stream such as natural gas starting from a feed stream.

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 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 present invention relates to the control systems of the compression refrigerating machines, namely, to the methods of control of the natural gas liquefaction process to produce liquefied natural gas (LNG), and can be used for liquefaction and cooling of natural gas on the most major technological lines and LNG production plants, working on the mixed refrigerant (MR). The method of control of the natural gas liquefaction process, on the mixed refrigerant-operating LNG production plant comprises a periodic measuring of the current parameters of the said process, and controlling composition of the mixed refrigerant entering the main cryogenic heat exchanger, in order to achieve the optimal process parameters. Carnot factor is used as an optimality criterion for parameters of the process. The mixed refrigerant composition is controlled by direct calculation on the basis of the current process parameters and equation of state (for example, Peng-Robinson equation of state) of the substance amount of the mixed refrigerant components required to obtain in the main cryogenic heat exchanger the temperature profile corresponding to the optimal process parameters, and to introduce the said components into the main cryogenic heat exchanger. The invention improves efficiency of the natural gas liquefaction process and, as a result, minimizes specific compressor power required for LNG production.

The present invention relates to a refrigerant composition comprising neon and hydrogen. The present invention further relates to the use of the refrigerant composition in liquefying gaseous substances such as hydrogen or helium.

A method for liquefying a stream of hydrocarbons from a feed stream, including introducing the feed stream and a first cooling stream into a first heat exchanger, extracting a plurality of partial cooling streams obtained from the first cooling stream from the heat exchanger via separate outlets, introducing each partial cooling stream into an expansion element to produce a plurality of biphasic cooling streams at different pressures, introducing each biphasic cooling stream into a phase separator element to produce a gaseous cooling stream which is diverted from the first exchanger and a liquid cooling stream which is introduced into the first exchanger via respective inlets, evaporating each liquid cooling stream by heat exchange with at least the feed stream and the first cooling stream so as to extract a cooled hydrocarbon stream at the outlet from the first heat exchanger and to extract a plurality of evaporated cooling streams.

A method of producing liquefied natural gas (LNG) is disclosed. A natural gas is compressed in at least two serially arranged compressors to a pressure of at least 2,000 psia and cooled to form a cooled compressed natural gas stream. The cooled compressed natural gas stream is additionally cooled to a temperature below an ambient temperature to form an additionally cooled compressed natural gas stream, which 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 by indirect heat exchange with a refrigerant to form liquefied natural gas and a warm refrigerant. The cooled compressed natural gas stream is additionally cooled using the warm refrigerant.

The invention relates to a of processing a liquid natural gas stream at a LNG import terminal. The method comprises operating a vaporization unit obtaining a pressurized vaporized natural gas stream and operating a slushification unit to obtain a slush of liquid and solids and a cooled vapour phase. The method further comprises withdrawing the cooled vapour phase from the slushifier providing a cooled vapour stream and passing the cooled vapour stream to the vaporization unit.

Disclosed herein is a boil-off gas reliquefaction apparatus. The boil-off gas reliquefaction apparatus includes: a plurality of compressors arranged in parallel to compress boil-off gas discharged from a storage tank; a reliquefaction unit reliquefying the boil-off gas compressed by each of the plurality of compressors; and a plurality of supply lines providing a path through which the boil-off gas is supplied from the plurality of compressors to the reliquefaction unit and a path through which the boil-off gas flows in the reliquefaction unit, wherein the plurality of supply lines is arranged independently of one another without being joined together.

Disclosed herein is a BOG reliquefaction system for LNG vessels. The BOG reliquefaction system includes a compressor compressing BOG, a heat exchanger cooling the compressed BOG by exchanging heat between the compressed BOG and BOG used as a refrigerant, and an expansion unit for expanding the BOG having been cooled by the heat exchanger, wherein the heat exchanger includes a core, in which heat exchange between a hot fluid and a cold fluid occurs, the core including a plurality of diffusion blocks, and a fluid diffusion member diffusing a fluid introduced into the core or a fluid discharged from the core.