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 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 cooling system drains oil from low side heat exchangers to vessels and then uses compressed refrigerant to push the oil in the vessels back towards a compressor. Generally, the cooling system operates in three different modes of operation: a normal mode, an oil drain mode, and an oil return mode. During the normal mode, a primary refrigerant is cycled to cool one or more secondary refrigerants. As the primary refrigerant is cycled, oil from a compressor may mix with the primary refrigerant and become stuck in a low side heat exchanger. During the oil drain mode, the oil in the low side heat exchanger is allowed to drain into a vessel. During the oil return mode, compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor.

A centrifugal-separation type oil separator includes a cylindrical separator body, and an inflow pipe arranged to introduce a fluid including an oil into the separator body. The inflow pipe includes a curved portion. The curved portion includes at least one oil draining hole.

A centrifugal-separation type oil separator includes a cylindrical separator body, and an inflow pipe arranged to introduce a fluid including an oil into the separator body. The inflow pipe includes a curved portion. The curved portion includes at least one oil draining hole.

This invention relates generally to oil lubricated helium compressor units for use in cryogenic refrigeration systems, operating on the Gifford McMahon (GM) cycle. This invention provides redundancy between water cooling and air cooling if there is a blockage in the water or air supply by having air and water cooled after-coolers in series or parallel.

This invention relates generally to oil lubricated helium compressor units for use in cryogenic refrigeration systems, operating on the Gifford McMahon (GM) cycle. This invention provides redundancy between water cooling and air cooling if there is a blockage in the water or air supply by having air and water cooled after-coolers in series or parallel.

This refrigerant vessel component (2, 4, 7) for a refrigeration circuit (100), comprises a shell (10) extending along a longitudinal axis (X) delimiting an internal volume (V), in which circulates a refrigerant fluid (R), whereas the refrigerant vessel component (2) comprises an inner shell (20) located radially inside the shell (10) and extending on at least a portion of the circumference of the shell (10), and whereas the inner shell (20) is at least partly formed of perforated material.

This refrigerant vessel component (2, 4, 7) for a refrigeration circuit (100), comprises a shell (10) extending along a longitudinal axis (X) delimiting an internal volume (V), in which circulates a refrigerant fluid (R), whereas the refrigerant vessel component (2) comprises an inner shell (20) located radially inside the shell (10) and extending on at least a portion of the circumference of the shell (10), and whereas the inner shell (20) is at least partly formed of perforated material.

A vaporizer includes an inner shell through which a refrigerant and oil mixture is flowed, and one or more hot gas pathways extending through the inner shell from a hot gas inlet to a hot gas outlet, through which a hot gas is flowed to boil refrigerant in the refrigerant and oil mixture. The inner shell is embedded in an outer shell. The outer shell defines a sump fluidly connected to the inner shell via a sump inlet line to deliver the refrigerant and oil mixture from the inner shell to the sump. A sump heater is located in the sump, which is configured to boil additional refrigerant from the refrigerant and oil mixture.