Disclosed is a BOG reliquefaction system. The BOG reliquefaction system includes: a compressor compressing BOG; a heat exchanger cooling the BOG compressed by the compressor through heat exchange using BOG not compressed by the compressor as a refrigerant; a pressure reducer disposed downstream of the heat exchanger and reducing a pressure of fluid cooled by the heat exchanger; and a second oil filter disposed downstream of the pressure reducer, wherein the compressor includes at least one oil-lubrication type cylinder and the second oil filter is a cryogenic oil filter.

Disclosed is a BOG reliquefaction system. The BOG reliquefaction system includes: a compressor compressing BOG; a heat exchanger cooling the BOG compressed by the compressor through heat exchange using BOG discharged from a storage tank as a refrigerant; a bypass line through which the BOG is supplied to the compressor after bypassing the heat exchanger; a second valve disposed on a second supply line through which the BOG used as the refrigerant in the heat exchanger is supplied to the compressor, the second valve regulating a flow rate of fluid and opening/closing of the second supply line; and a pressure reducer disposed downstream of the heat exchanger and reducing a pressure of fluid cooled by the heat exchanger, wherein the compressor includes at least one oil-lubrication type cylinder and the bypass line is joined to the second supply line downstream of the second valve.

A method for subcooling liquid cryogen that is used by a cutting tool uses the steps of dividing liquid phase cryogen between a subcooler feed line and tool feed line. The cryogen in the subcooler feed line is expanded to lower the pressure and decrease the temperature of the cryogen, and the expanded liquid cryogen from the subcooler feed line is added to the interior of a subcooler. A heat exchanger is positioned in the subcooler in contact with the expanded liquid cryogen. The cryogen in the tool feed line is subcooled below its saturation temperature by passing the cryogen through the heat exchanger, and the subcooled cryogen from the heat exchanger is supplied to the cutting tool. As a result, the subcooled cryogen supplied to the cutting tool is substantially 100% liquid cryogen without any vapor content.

A body structure has an inlet port that receives fluid, a first outlet port that connects to a top-fill line of a cryogenic tank, a second outlet port that connects to a bottom-fill line of a cryogenic tank and a slider tube cylinder. A cylinder housing connects to the body structure and has a pressure comparison cylinder with upper and lower volumes, with the latter in fluid communication with a cryogenic tank. A piston having a piston shaft slides within the pressure comparison cylinder. A pressure regulator is in fluid communication with the upper volume and the slider tube cylinder. A slider tube is connected to the piston shaft and slides within the slider tube cylinder. The slider tube cylinder selectively directs fluid to a top-fill line through the first outlet port or to a bottom-fill line through the second outlet port.

A method for storage and transport of LPG on LPG carriers, in particular two cargoes of different LPG types on same shipment, having reliquefaction units in which vaporized gases are condensed and then returned into at least one cargo tank for the respective LPG cargo type. The method is further comprising: using the reliquefaction units, at a minimum one running, as to condense vapour from the first cargo type; passing the condensed vapour through a heat exchanger; simultaneously flowing vapour from the second cargo type through the heat exchanger as to condense vapour by means of heat exchanging with the condensed vapour; and returning the condensed vapours leaving the heat exchanger back into the respective cargo types. The present invention is also disclosing a system for storage and transport of LPG on LPG carriers.

A body structure has an inlet port that receives fluid, a first outlet port that connects to a top-fill line of a cryogenic tank, a second outlet port that connects to a bottom-fill line of a cryogenic tank and a slider tube cylinder. A cylinder housing connects to the body structure and has a pressure comparison cylinder with upper and lower volumes, with the latter in fluid communication with a cryogenic tank. A piston having a piston shaft slides within the pressure comparison cylinder. A pressure regulator is in fluid communication with the upper volume and the slider tube cylinder. A slider tube is connected to the piston shaft and slides within the slider tube cylinder. The slider tube cylinder selectively directs fluid to a top-fill line through the first outlet port or to a bottom-fill line through the second outlet port.

A BOG reliquefaction system includes: a compressor; a heat exchanger cooling the BOG compressed by the compressor through heat exchange using BOG not compressed by the compressor; a pressure reducer disposed downstream of the heat exchanger and reducing a pressure of fluid cooled by the heat exchanger; and a combination of a first temperature sensor disposed upstream of a cold fluid channel of the heat exchanger and a fourth temperature sensor disposed downstream of a hot fluid channel of the heat exchanger, combination of a second temperature sensor disposed downstream of the cold fluid channel of the heat exchanger and a third temperature sensor disposed upstream of the hot fluid channel of the heat exchanger, or combination of a first pressure sensor disposed upstream of the hot fluid channel of the heat exchanger and a second pressure sensor disposed downstream of the hot fluid channel of the heat exchanger.

Disclosed is a liquefied natural gas storage apparatus. The apparatus includes a heat insulated tank and liquefied natural gas contained in the tank. The tank has heat insulation sufficient to maintain liquefied natural gas therein such that most of the liquefied natural gas stays in liquid. The contained liquefied natural gas has a vapor pressure from about 0.3 bar to about 2 bar. The apparatus further includes a safety valve configured to release a part of liquefied natural gas contained in the tank when a vapor pressure of liquefied natural gas within the tank becomes higher than a cut-off pressure. The cut-off pressure is from about 0.3 bar to about 2 bar.

A method of recondensing boil off gas includes receiving liquefied natural gas from a storage tank and increasing the pressure of the received liquefied natural gas to produce increased pressure liquefied natural gas. The method further includes receiving boil off gas from the storage tank at a gas inlet of an ejector, and receiving the increased pressure liquefied natural gas at a liquefied gas inlet of the ejector. The pressure of the increased pressure liquefied gas is used as a motive force to eject combined liquefied natural gas and boil off gas at a pressure greater than that of the boil off gas received at the gas inlet of the ejector. The method additionally includes increasing the pressure of the fluid ejected from the ejector to produce increased pressure ejected fluid.

The invention relates to a gas treatment method and system of a gas storage facility (2), in particular on board a ship, the method comprising the following stages: an extraction of a first gas (4a, 4b, 5a, 5b,) in the liquid state from a first tank (4) or first vessel (5; 500), a first subcooling of the first gas in the liquid state, and storage of the subcooled first gas in the liquid state in the lower part of the first tank (4) or of the first vessel (5; 500) or of a second tank or of a second vessel, so as to constitute a reserve layer of cold (4c, 5c, 500c) of the subcooled first gas in the liquid state at the bottom of the first or second tank (4) or of the first or second vessel (5; 500).