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.

The present disclosure provides a system and method of efficiently designing a compact and modularized midscale liquefied natural gas production train. The train includes Natural Gas Pretreatment and Natural Gas Liquefaction sections designed in a unique way that reduces footprint, capital and operating cost, and overall project schedule. The train is configured into a framed compact multi-level structure with air coolers on the top level and process equipment underneath, which results in significant reduction in footprint compared to conventional stick-built design and significant reduction in footprint compared to conventional modularized design.

Provided is a cooling device with which it is possible to cool a fluid to be cooled, even before maintenance work, if a fault such as a blockage or a breakage occurs in a part of a channel. The cooling device (1) is provided with four heat exchangers (1A-1D) and a plurality of heat exchanger connection parts (111-120), each of the heat exchanger connection parts allowing natural gas to flow therethrough. Each of the heat exchangers has: a drum (101, 102, 103, fourth drum 104), a refrigerant reservoir (T), a plurality of heat exchanger core parts (121, 122, 123, 124) immersed in liquid propane in the refrigerant reservoir (T), and a demister (106). A plurality of cooling channels allowing natural gas to flow therethrough are installed, independent of each other, from the first heat exchanger (1A) to the fourth heat exchanger (1D).

Low-temperature refrigeration device arranged in a frame and comprising a working circuit forming a loop and containing a working fluid, the working circuit forming a cycle comprising in series: a compression mechanism, a cooling mechanism, an expansion mechanism and a heating mechanism, the device comprising a refrigeration heat exchanger intended to extract heat from at least one member by exchanging heat with the working fluid, the mechanisms for cooling and reheating the working fluid comprising a common heat exchanger in which the working fluid transits in counter-flow in two separate transit portions of the working circuit, the compression mechanism comprising at least two compressors and at least one motor for driving the compressors, the working fluid expansion mechanism comprising at least one rotary turbine, the device comprising at least one drive motor comprising a drive shaft, one end of which drives a compressor and the other end of which is coupled to a turbine, the motor being attached to the frame at at least one fixed point, the common heat exchanger being attached to the frame at at least one fixed point, the two counter-flow transit portions of the common heat exchanger being orientated in a longitudinal direction of the frame, the drive shaft of the drive motor being orientated in a direction parallel or substantially parallel to the longitudinal direction and the turbine and the compressor being arranged relatively longitudinally such that the turbine is located longitudinally on the side corresponding to the relatively cold end of the common heat exchanger when the device is being operated and the compressor is located longitudinally on the side corresponding to the relatively hot end of the common heat exchanger when the device is being operated.

Disclosed is a low-temperature refrigeration device which is arranged in a frame and comprises a working circuit that 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, wherein the mechanisms for cooling and heating the working fluid comprise a common heat exchanger in which the working fluid flows in opposite directions in two separate transit portions of the working circuit, 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, wherein the frame extends in a longitudinal direction and comprises a lower base intended to be mounted on a support, the cooling heat exchangers are located in the frame about the common heat exchanger, i.e. the cooling heat exchangers are not located below the common heat exchanger between the common heat exchanger and the lower base of the frame.

A system for processing liquified natural gas can include: a natural gas feed; a cold box; one or more natural gas cooling components; and a storage tank configured to store a refrigerant, wherein the one or more natural gas cooling components and the storage tank are located within the cold box. The cold box can be a methane cold box and the refrigerant can be propane, ethane, or ethylene. The system can also include a propane refrigerant cycle and/or an ethylene refrigerant cycle. Refrigerant stored in the methane cold box can be used to replenish refrigerant lost in the propane/ethylene cycles. The cold box can be an ethylene cold box of the ethylene refrigerant cycle. Propane can be stored in the ethylene cold box. A second storage tank can be located within a methane cold box and store ethane or ethylene.

A process for producing liquefied natural gas, in which natural gas feed having methane and higher hydrocarbons including benzene is cooled down to a first temperature level in a first cooling step using a first mixed coolant and then subjected to a countercurrent absorption using an absorption liquid to form a methane-enriched and benzene-depleted gas fraction, wherein a portion of the gas fraction is cooled down to a second temperature level in a second cooling step using a second mixed coolant and liquefied to give the liquefied natural gas. In the plant proposed, the first and second mixed coolants are low in propane or free of propane, and the absorption liquid is formed from a further portion of the gas fraction which is condensed above the countercurrent absorption and returned to the countercurrent absorption without pumping. The present invention likewise provides a corresponding plant.

A system for removing selected components from a gas stream has a heat exchanger including a first cooling passage configured to receive a feed gas stream and to provide a cooled feed gas stream. An expander receives at least a portion of the cooled feed gas stream. A separation device receives an expanded fluid stream from the expander and separates the expanded fluid stream into a liquid stream containing selected components and a purified vapor stream having a purified vapor temperature. A compressor receives the purified vapor stream at approximately the purified vapor temperature and produces a compressed vapor stream that is returned to the heat exchanger.

A system for cooling a gas with a mixed refrigerant includes a heat exchanger that receives and cools a feed of the gas so that a product is produced. The system includes a mixed refrigerant processing system having compression devices and aftercoolers as well as a low pressure accumulator and a high pressure accumulator. A cold vapor separator receives vapor from the high pressure accumulator and features a vapor outlet and a liquid outlet. Vapor from the cold vapor separator vapor outlet is cooled, expanded and directed to a primary refrigeration passage of the heat exchanger. Liquid from the liquid outlet of the cold vapor separator is subcooled, expanded and directed to the primary refrigeration passage. Liquid from the low pressure accumulator is subcooled, expanded and directed to the primary refrigeration passage. Liquid from the high pressure accumulator is subcooled, expanded and directed to the primary refrigeration passage.

A system for cooling a gas with a mixed refrigerant includes a heat exchanger that receives and cools a feed of the gas so that a product is produced. The system includes a mixed refrigerant processing system having compression devices and aftercoolers as well as a low pressure accumulator and a high pressure accumulator. A cold vapor separator receives vapor from the high pressure accumulator and features a vapor outlet and a liquid outlet. Vapor from the cold vapor separator vapor outlet is cooled, expanded and directed to a primary refrigeration passage of the heat exchanger. Liquid from the liquid outlet of the cold vapor separator is subcooled, expanded and directed to the primary refrigeration passage. Liquid from the low pressure accumulator is subcooled, expanded and directed to the primary refrigeration passage. Liquid from the high pressure accumulator is subcooled, expanded and directed to the primary refrigeration passage.