Provided is a technology of searching for operation guidance for efficiently operating a liquefied natural gas plant An operation guidance searching method for a liquefied natural gas plant includes: acquiring data sets of operation data of process variables for a plurality of target devices and disturbance data; generating, through machine learning, a plant model indicating correspondences of output values of process variables with respect to manipulated variables and input values of disturbances; and searching, through reinforcement learning, for input values of the manipulated variables operation variables for with which a compression power per unit production amount is minimized under a condition in which an outlet temperature of a liquefied natural gas is a preset restriction temperature or lower.

A liquefier device which may be a retrofit to an air separation plant or utilized as part of a new design. The flow needed for the liquefier comes from an air separation plant running in a maxim oxygen state, in a stable mode. The three gas flows are low pressure oxygen, low pressure nitrogen, and higher pressure nitrogen. All of the flows are found on the side of the main heat exchanger with a temperature of about 37 degrees Fahrenheit. All of the gasses put into the liquefier come out as a subcooled liquid, for storage or return to the air separation plant. This new liquefier does not include a front end electrical compressor, and will take a self produced liquid nitrogen, pump it up to a runnable 420 psig pressure, and with the use of turbines, condensers, flash pots, and multi pass heat exchangers. The liquefier will make liquid from a planned amount of any pure gas oxygen or nitrogen an air separation plant can produce.

The present invention pertains to a cooling method for liquefying a feed gas, comprising the steps of providing a cooling cycle with a refrigerant stream; dividing the refrigerant stream into a first partial stream and a second partial stream; expanding the first partial stream in a first expansion device; and transferring cooling energy from the expanded first partial stream to a feed gas stream to be cooled, particularly comprising hydrogen and/or helium. Further the method comprises the steps of guiding the expanded first partial stream to a suction inlet of an ejector; and guiding the second partial stream to a propellant inlet of the ejector such that, upon expanding the second partial stream in the ejector, the expanded first partial stream is compressed and merged with the expanded second partial stream.

The present disclosure provides a heat axchanger and heat exchange method for cooling a gaseous process stream. The heat exchanger unit (100, 200, 300) comprises: a heat exchanger vessel (2), the heat exchanger vessel (2) comprising a plurality of process stream conduits (12, 14) arranged to receive the gaseous process stream (10) and discharge a cooled process stream (18), and a plurality of refrigerant conduits (46, 48, 49) to receive at least part of a pre-cooled mixed refrigerant stream (58) and to discharge at least one cooled mixed refrigerant stream (72, 82); at least one expansion device (74, 84) arranged to receive at least part of the cooled mixed refrigerant stream (72, 82) and discharge a further cooled mixed refrigerant stream (76, 86), the further cooled mixed refrigerant stream (76, 86) being connected to at least one of a third refrigerant inlet (77) and a fourth refrigerant inlet (87) of the heat exchanger vessel (2) to provide cooling to the process stream conduits (12, 14) and the refrigerant conduits (46, 48, 49); a refrigerant bleed vessel (110) arranged to receive a first refrigerant split-off stream (112) from the cooled mixed refrigerant stream (72, 82) and to receive a second refrigerant split-off stream (114) from the pre-cooled mixed refrigerant stream; the refrigerant bleed vessel (110) comprising a bleed outlet (116) to discharge a bleed stream (118) and a recycle outlet (120) to discharge a recycle stream (122), the recycle outlet being fluidly connected to at least one of the third refrigerant inlet (77) and the fourth refrigerant inlet (87) of the heat exchanger vessel (2).

Process for eliminating the evaporation of a liquefied natural gas stream during the transfer thereof into a storage facility, comprising the following steps: Step a): liquefaction, by means of a refrigeration cycle, of a natural gas stream and of a nitrogen stream in a main heat exchanger; Step b): cooling of the liquefied natural gas stream from step a) in a second heat exchanger by circulation of said liquefied natural gas stream countercurrent to a liquid nitrogen flow that is vaporized while cooling said liquefied natural gas stream; wherein the liquid nitrogen flow used in step b) is from step a).

A LNG liquefaction plant includes a propane recovery unit including an inlet for a feed gas, a first outlet for a LPG, and a second outlet for an ethane-rich feed gas, an ethane recovery unit including an inlet coupled to the second outlet for the ethane-rich feed gas, a first outlet for an ethane liquid, and a second outlet for a methane-rich feed gas, and a LNG liquefaction unit including an inlet coupled to the second outlet for the methane-rich feed gas, a refrigerant to cool the methane-rich feed gas, and an outlet for a LNG. The LNG plant may also include a stripper, an absorber, and a separator configured to separate the feed gas into a stripper liquid and an absorber vapor. The stripper liquid can be converted to an overhead stream used as a reflux stream to the absorber.

A method of cooling a boil off gas stream from a liquefied cargo (50a) in a floating transportation vessel is described. The method comprises: compressing a boil off gas stream in two or more stages of compression to provide a compressed BOG discharge stream; cooling the compressed BOG discharge stream against one or more first coolant streams to provide a first cooled compressed BOG stream; cooling the first cooled compressed BOG stream against at least one second coolant stream to provide a second cooled compressed BOG stream; providing a vessel fuel stream from the liquefied cargo; using the vessel fuel stream as a coolant stream to cool either the compressed BOG discharge stream, or the first cooled compressed BOG stream, or both said streams.

The invention relates to a method for condensing a gas, wherein the gas is subjected to cooling in indirect heat exchange with a refrigerant and at least part of the refrigerant is subjected, after the heat exchange with the gas, to compression by means of a drive (GT1) that produces waste heat and to a partial or complete condensing process. After the partial or complete condensing process, a first portion of the refrigerant is subjected to the heat exchange with the gas and a second portion of the refrigerant is subjected, in succession, to pressurization, heating by means of the waste heat of the drive (GT1) and work-performing expansion and thereafter is fed back to the partial or complete condensing process. The invention further relates to a corresponding system.

Liquefier arrangements configured for co-production of both liquid natural gas (LNG) and liquid nitrogen (LIN) configured to operate in two distinct operating modes are provided.

A simple and efficient single mixed refrigerant process for cooling and liquefying a hydrocarbon feed stream, such as natural gas. The process employs a closed-loop single mixed refrigerant process for refrigeration duty. The refrigerant compressed to a high pressure using at least three stages of compression and two intercoolers (both producing liquid). A hydraulic turbine is used to expand the high pressure refrigerant before it flows into the main heat exchanger.