Disclosed is a low-temperature refrigeration device comprising a working circuit that forms a loop and contains a working fluid the working circuit forming a cycle which includes, connected in series: a compression mechanism, a cooling mechanism, an expansion mechanism and a heating mechanism, the device further comprising a refrigeration heat exchanger for extracting heat from at least one member by exchanging heat with the working fluid flowing in the working circuit, the compression mechanism comprising two separate compressors, the mechanism for cooling the working fluid comprising two cooling heat exchangers which are arranged respectively at the outlet of the two compressors and ensure heat exchange between the working fluid and a cooling fluid, each cooling heat exchanger comprising a cooling fluid inlet and a cooling fluid outlet, characterized in that the cooling fluid outlet of one of the two cooling heat exchangers is connected to the cooling fluid inlet of the other cooling heat exchanger.

Method for hydrogen liquefaction comprising at least one precooling step, wherein a hydrogen feed flow is cooled by a first refrigerant, a cooling step, wherein the hydrogen feed flow is cooled by a second refrigerant, and a step of expanding the hydrogen feed flow. Each of the first and second refrigerants is successively subjected to at least one compression and to at least one expansion in order to cool it, and a liquid phase of the first refrigerant cools the second refrigerant between at least three stages of said compression so that the second refrigerant does not exceed a temperature of 150 K, optionally 113 K, during said compression of the second refrigerant.

The present invention is a modification of a typical single mixed refrigerant (SMR) cycle for LNG re-liquefaction in particular, that allows the use of a cost-efficient oil-injected screw compressor in the mixed refrigerant system. In comparison with the typical arrangement, the present innovation allows for reduced complexity, fewer pieces of equipment, and reduced capital cost. There is shown a method of cooling a boil-off gas (BOG) stream from a liquefied gas tank using a single mixed refrigerant (SMR) comprising at least the step of heat exchanging the BOG stream with the SMR in a liquefaction heat exchanger system to provide a cooled BOG stream, wherein the SMR is provided in an SMR recirculating system comprising at least the steps of: (a) compressing the SMR using at least one oil-injected screw compressor to provide a post-compression SMR stream; (b) separating the post-compression SMR stream to provide an oil-based stream and a first SMR vapour stream; (c) passing the first SMR vapour stream into the liquefaction heat exchanger system to cool the first SMR vapour stream and provide a cooled first SMR vapour stream; (d) withdrawing the cooled first SMR vapour stream from the liquefaction heat exchanger system; (e) separating the cooled first SMR vapour stream to provide a liquid-phase SMR stream and an oil-free SMR vapour stream; (f) passing the oil-free SMR vapour stream through the liquefaction heat exchanger system to provide a condensed SMR stream; and (g) expanding the condensed SMR stream to provide an expanded lowest-temperature SMR stream to pass through the liquefaction heat exchanger system for heat exchange against the BOG stream.

A system and method for removal of a contaminant comprising removing a liquefied portion of a refrigerant stream comprising nitrogen from a reverse Brayton cycle refrigerant system, introducing the liquefied refrigerant stream into a contaminant removal column as a reflux stream removing a contaminant stream from the bottom of the contaminant removal column, removing a vapor stream enriched in nitrogen from the top of the contaminant removal column, and introducing the vapor stream enriched in nitrogen back into the reverse Brayton cycle refrigerant system.

An apparatus for producing a liquefied gas using a Rankine cycle is provided. The apparatus includes a first compression means for adiabatically compressing a heat transfer medium; a first heat exchanger for constant pressure heating the adiabatically compressed heat transfer medium; a plurality of parallelly arranged expansion means for adiabatically expanding the heated heat transfer medium; a second heat exchanger for constant pressure cooling the adiabatically expanded heat transfer medium; and a flow passageway for guiding the heat transfer medium that has been guided out from the second heat exchanger to the first compression means.

The present invention relates to a method and system for producing liquefied natural gas (LNG) from a stream of pressurized natural gas which involves a combination of mechanical refrigeration.

A system and method for cooling a gas using a mixed refrigerant includes a compressor system and a heat exchange system, where the compressor system may include an interstage separation device or drum with no liquid outlet, a liquid outlet in fluid communication with a pump that pumps liquid forward to a high pressure separation device or a liquid outlet through which liquid flows to the heat exchanger to be subcooled. In the last situation, the subcooled liquid is expanded and combined with an expanded cold temperature stream, which is a cooled and expanded stream from the vapor side of a cold vapor separation device, and subcooled and expanded streams from liquid sides of the high pressure separation device and the cold vapor separation device, or combined with a stream formed from the subcooled streams from the liquid sides of the high pressure separation device and the cold vapor separation device after mixing and expansion, to form a primary refrigeration stream.

A method includes directing a refrigerant fluid mixture and a flow of natural gas through a first heat exchanger for exchanging heat between a natural gas flow path and a first refrigerant flow path. The method also includes expanding the flow of natural gas exiting from the first heat exchanger via a first throttle valve. Further, the method also includes directing a generated cold natural gas vapor and a slurry having a liquefied natural gas and solidified carbon dioxide through a filter sub-assembly. Moreover, the method also includes separating the solidified carbon dioxide by the filter sub-assembly to form a purified liquefied natural gas. Finally, the method includes directing a pulse of a cleaning fluid having at least one of methane and carbon dioxide through the filter sub-assembly to remove the solidified carbon dioxide therefrom and storing the purified liquefied natural gas in a storage tank assembly.

Method and installation for refrigerating the same application by means of several refrigerators/liquefiers disposed in parallel, the refrigerators/liquefiers in parallel using a working gas of the same nature having a low molar mass, that is to say having a mean total molar mass of less than 10 g/mol such as pure gaseous helium, each refrigerator/liquefier comprising a station for compressing the working gas, a cold box intended to cool the working gas at the output from the compression station, the working gas cooled by each of the respective cold boxes of the refrigerators/liquefiers being put in thermal exchange with the application with a view to supplying cold to the latter, in which a single compression station compresses the working gas for each of the respective separate cold boxes of the refrigerators/liquefiers disposed in parallel, the single compression station comprising only compression machines of the lubricated-screw type and systems for removing oil from the working fluid output from the compression machines, so that the compression machines and the oil-removal systems are shared by the refrigerators/liquefiers disposed in parallel.

Natural gas boiling off from LNG storage tanks located on board a sea-going vessel, is compressed in a plural stage compressor. At least part of the flow of compressed natural gas is sent to a liquefier operating on a Brayton cycle in order to be reliquefied. The temperature of the compressed natural gas from the final stage is reduced to below 0 C. by passage through a heat exchanger. The first compression stage is operated as a cold compressor and the resulting cold compressed natural gas is employed in the heat exchanger to effect the necessary cooling of the flow from the compression stage. Downstream of its passage through the heat exchanger the cold compressed natural gas flows through the remaining stages of the compressor. If desired, a part of the compressed natural gas may be supplied to the engines of the sea-going vessel as a fuel.