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) passing the first warmer refrigerant stream through an entry port located in a second zone of the heat exchanger that is warmer than the first zone (d) passing an oil-containing refrigerant stream through an entry port located in a second zone of the heat exchanger that is warmer than the first zone; (e) mixing the first warmer refrigerant stream and the oil-containing stream in the heat-exchanger to form a combined refrigerant stream; and (f) passing the combined refrigerant stream out of the heat exchanger through the warmer exit port.

Disclosed is a refrigeration and/or liquefaction method using a system that includes a low-temperature refrigeration device comprising a working circuit which forms a loop and contains a working fluid, the working circuit forming a cycle comprising, connected in series: a compression mechanism, a cooling mechanism, an expansion mechanism and a heating mechanism the refrigeration device further comprising a cooling exchanger for extracting heat from the useful fluid stream by exchanging heat with the working fluid flowing in the working circuit, the system comprising a pipe through which the useful fluid stream flows in the cooling exchanger, the method comprising a cooling step in which the refrigeration device is in a first operating mode for cooling the cooling exchanger while a useful fluid stream flows in the cooling exchanger, the method comprising, after said cooling step, a step of cleaning impurities that have solidified in the cooling exchanger, characterized in that during the cleaning step, the refrigeration device is in a second operating mode in which the working gas flows in the working circuit but in which the cooling exchanger cools less intensely than in the first operating mode.

The invention relates to a method for cooling and/or liquefying a user fluid flow the method using a cooling and/or liquefying system comprising a low-temperature refrigeration device, the refrigeration device comprising a working circuit forming a loop and containing a working fluid, the refrigeration device comprising a cooling exchanger intended to extract heat from the user fluid flow by heat exchange with the working fluid circulating in the working circuit, the working circuit forming a cycle comprising, in a series: a compression mechanism a cooling mechanism, an expansion mechanism, and a reheating mechanism, the system comprising a pipe for circulation of the user fluid flow to be cooled in heat exchange with the cooling exchanger of the refrigeration device, the method comprising a step of cooling a user fluid flow in the cooling exchanger and after this cooling step, a step of cleaning impurities solidified in the cooling exchanger, the cleaning step comprising stopping of the refrigeration device and simultaneously, circulation of a user fluid flow in the cooling exchanger.

There is provided 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 centrifugal compressor to provide a post-compression SMR stream; (b) passing the post-compression SMR stream into the liquefaction heat exchanger system to cool the post-compression SMR stream and provide a cooled first SMR vapour stream; (c) withdrawing the cooled first SMR vapour stream from the liquefaction heat exchanger system; (d) separating the cooled first SMR vapour stream to provide a liquid-phase SMR stream and a light SMR vapour stream; (e) passing the light SMR vapour stream through the liquefaction heat exchanger system to provide a condensed SMR stream; and (f) 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 boil-off gas supply device is provided with: a storage tank configured to store a liquefied gas; a first compression mechanism configured to suck in the boil-off gas of the liquefied gas stored in the storage tank and compress the sucked boil-off gas; a second compression mechanism configured to compress the boil-off gas after being compressed by the first compression mechanism; a discharge path in which the boil-off gas discharged from the second compression mechanism flows; a first drive source configured to drive the first compression mechanism; and a second drive source that is different from the first drive source and configured to drive the second compression mechanism.

A liquefied natural gas (LNG) management system that stores natural gas in a liquefied state in an isothermal storage tank. A modular multi-fueling platform is in fluid communication with the isothermal storage tank. The modular multi-fueling platform includes a LNG conditioning tank, a compressor, a heat exchanger, a heater, plumbing, associated valves, various sensing transmitters, and a programmable logic computer (PLC). Data acquired by the PLC determines actions by the modular multi-fueling platform, including operation of valves, the compressor, etc. The system transfers LNG between the storage tank, the conditioning tank, and a cargo tank (consumer's vehicle tank). The system employs steps of heating and compressing the LNG and boil off gas to maintain the LNG at temperature. The system employs pressure differences for transferring the LNG between tanks.

The present invention pertains to a method for filling a transport tank with a product medium in a liquid state in a gas liquefaction plant, comprising a step of supplying the product medium in the liquid state from a storage tank (18) of the gas liquefaction plant to the transport tank. The method is characterized in that it further comprises a step of discharging the product medium in a gaseous state from the transport tank into the storage tank (18).

A ship comprises: a tank; a multistage compressor for compressing a boil-off gas discharged from a storage tank and comprising a plurality of compression cylinders; a first heat exchanger for heat exchanging a fluid, which has been compressed by the multistage compressor, with the boil-off gas discharged from the storage tank and thus cooling the same; a first decompressing device for expanding a flow (“flow a1”) partially branched from the flow (“flow a”) that has been cooled by the first heat exchanger; a third heat exchanger for heat exchanging, by “flow a1” which has been expanded by the first decompressing device as a refrigerant, the remaining flow (“flow a2”) of “flow a” after excluding “flow a1” that has been branched and thus cooling the same; and a second decompressing device for expanding “flow a2” which has been cooled by the third heat exchanger.

Systems and methods are described for increasing capacity and efficiency of a nitrogen refrigerant boil-off gas recovery system for a natural gas storage tank. Boil-off gas is condensed against two-phase nitrogen in a condensing heat exchanger having an inner vessel through which the boil-off gas flows and an outer vessel through which the two phase nitrogen flows. Logic controls maintain storage tank pressure and power consumption within preferred levels by adjusting the pressure of the two-phase nitrogen in the heat exchanger. Additional logic controls maintain the temperature difference between the nitrogen streams entering into and returning from the cold end of a second heat exchanger by controlling the position of an expansion valve on the return circuit.

A system for natural gas cooling using nitrogen. The system can include a nitrogen liquefier and a natural gas cooler. The nitrogen liquefier can provide liquid nitrogen to the natural gas cooler. One or more heat exchangers of the natural gas cooler can include a gaseous nitrogen output that is in fluid communication with the nitrogen liquefier. In response to receiving gaseous nitrogen at the nitrogen liquefier, from the one or more heat exchangers, a production rate of the the nitrogen liquefier is adjusted.