A method of cooling a boil-off gas (BOG) stream from a liquefied gas tank comprising at least the step of heat exchanging the BOG stream with a first refrigerant in a heat exchanger, the heat exchanger having an entry port and a warmer exit port, and comprising at least the steps of: (a) passing the first refrigerant into the entry port of the heat exchanger and into a first zone of the heat exchanger to exchange heat with the BOG stream, to provide a first warmer refrigerant stream; (b) withdrawing the first warmer refrigerant stream from the heat exchanger at an intermediate exit port between the entry port and the warmer exit port; (c) admixing the first warmer refrigerant stream with an oil-containing refrigerant stream to provide a combined refrigerant stream; (d) passing the combined refrigerant stream into the heat exchanger through an entry port located in a second zone of the heat exchanger that is warmer than the first zone; (e) passing the combined refrigerant stream out of the heat exchanger through the warmer exit port. The present invention is a modification of a refrigerant cycle for BOG cooling, and LNG re-liquefaction in particular, that allows the use of a cost-efficient oil-injected screw compressor in the refrigerant system. The present invention is also able to accommodate the possibility of different flows or flow rates of the first refrigerant stream and the oil-containing refrigerant stream, such that there is reduced or no concern by the user of the process in relation to possible oil freezing and clogging of the heat exchanger caused by variation of the flow or flow rate of the oil-containing refrigerant stream.

A system for removing freezing components from a feed gas includes a heavy hydrocarbon removal heat exchanger and a scrub device. The scrub device includes a scrub column that receives a cooled feed gas stream from the heat exchanger and a reflux separation device. Vapor from the scrub column is directed to the heat exchanger and cooled to create a reflux stream that includes a liquid component. This reflux stream is directed to the reflux separation device and a resulting liquid component stream is used to reflux the column. Vapor from the reflux separation device is expanded and directed to the heat exchanger, where it provides refrigeration, and a processed feed gas line.

An LNG production plant is constructed from a plurality of containerised LNG liquefaction units. Each containerised LNG liquefaction unit can produce a predetermined quantity of LNG. For example, up to 0.3 MPTA. A manifold system enables connection between the plurality of containerised LNG liquefaction units, and at least a feed stream of natural gas, a source of electrical power, and an LNG storage facility. The production capacity of the plant is incrementally changed by connecting or disconnecting containerised LNG liquefaction units to or from the plant via the manifold system. Each unit contains its own liquefaction plant having a closed loop SMR circuit. Refrigerant within the SMR circuit is circulated solely by pressure differential generated by refrigerant compressors in the liquefaction plant.

A liquefied gas cooling apparatus including: a gas flow path for carrying a liquefied gas that is liquefied by cooling; and a refrigeration unit including a refrigerating cycle formed by an evaporator for cooling the liquefied gas flowing through the gas flow path, a compressor, a condenser, and a throttle expansion unit. The compressor is driven through an electric motor contained in a sealed housing together with a compressor mechanism.

A method of recycling liquefied natural gas (LNG) boil-off gas (BOG) in natural gas liquefaction plants can include: supplying a feed gas to a liquefaction subsystem; liquefying the feed gas to produce LNG and end-flash gas (EFG); compressing the EFG to compressed EFG; using the compressed EFG as fuel gas; storing the LNG in one or more LNG tanks; compressing LNG BOG from the one or more LNG tanks to produce compressed LNG BOG; and either (1) operating in a recycle mode by supplying at least a portion of the compressed LNG BOG to the feed gas via a bidirectional line, or (2) operating in a fuel mode by (a) supplying a portion of the feed gas to the fuel gas via the bidirectional line and (b) supplying the compressed LNG BOG to the fuel gas.

A system and method is provided for increasing the capacity and efficiency of natural gas liquefaction processes by debottlenecking the refrigerant compression system. A secondary compression circuit comprising at least one double flow compressor is provided in parallel fluid flow communication with at least a portion of a primary compression circuit.

A mixture of hydrocarbons in vapour phase is passed through a feed scrubber. Feed scrubber vapour discharged from the feed scrubber is passed to a compression suction scrubber, and a vaporous compressor feed stream from the compression suction scrubber is compressed in a compressor train. A compressed vaporous discharge stream from the train of compressors is de-superheated, and at least a portion of the de-superheated stream is passed to a condenser, wherein this portion of the de-superheated stream is at least partly condensed to form a pressurized and at least partially condensed mixture of hydrocarbons. A recycle portion is split off from the de-superheated hydrocarbon stream, and a recycle flow is established to the compressor train of via a surge recycle separator drum and the compression suction scrubber. Liquid constituents removed and drained from the recycle portion in the surge recycle separator drum are fed to the feed scrubber.

The device (600) for liquefying a natural gas comprises: a first centrifugal compressor (605), a fractionating means (110), a second centrifugal compressor (610), a first heat exchange body (115), a second heat exchange body (120) and a return conduit (125) leading to the first compressor, upstream of an inlet (116) in the first exchange body, a third heat exchange body (420), a third centrifugal compressor (620), the first and third centrifugal compressors being actuated by a single common turbine (630), a casing (635) common to the first compressor and the third compressor, a cooling means (430) and a transfer conduit (435) leading to the third exchange body.

The invention relates to an installation and a process for production of a cryogenic fluid, in particular of liquefied hydrogen, comprising, positioned in at least one cold box, a set of heat exchangers in thermal exchange with the circuit for hydrogen to be cooled, the installation comprising a device for pre-cooling, which is configured to pre-cool the circuit for gas to be cooled to a first determined temperature, and a device for cryogenic cooling which is configured to cool the circuit for gas to be cooled to a second determined temperature, lower than the first temperature, the cycle gas cooling unit and/or the cycle gas heating unit comprise(s) one or more first cycle heat exchangers distinct from the first part of the pre-cooling heat exchangers of the circuit for the gas to be cooled, these first cycle heat exchangers also being cooled by thermal exchange with the pre-cooling fluid circuit of the pre-cooling device.

A thermodynamic system containing a working fluid is disclosed. The thermodynamic system comprises at least a working fluid collection vessel (11) adapted to contain a liquid phase and a gaseous phase of the working fluid in thermodynamic equilibrium. A chilling arrangement (51) is functionally coupled to the fluid collection vessel (11) and adapted to remove heat from the working fluid collected in the working fluid collection vessel (11) and thereby reduce pressure in said thermodynamic system. Also disclosed are methods for depressurizing a thermodynamic system containing a working fluid in liquid/gas equilibrium.