The present invention relates to a method for cooling down a liquefaction system for liquefying a hydrocarbon-containing gas stream. The method for cooling down the liquefaction system comprises: a) performing a pre-cool-down procedure to cool down the pre-cooling stage, b) performing a cryogenic cool-down procedure to cool down the main cooling stage. B) comprises forming a main cool-down stream (201) that meets a predetermined C.sub.n.sup.+specification. The main cool-down stream (201) is formed out of at least one auxiliary stream not being the pre-cooled hydrocarbon containing gas stream, and the cryogenic cool down procedure and the pre-cool down procedure are at least partially performed simultaneously.

A method for controlling the flow of natural gas and refrigerant in the main heat exchanger of a natural gas liquefaction facility. The method provides for the automated control of a flow rate of a natural gas feed stream through a heat exchanger based on one or more process variables and set points. The flow rate of refrigerant streams through the heat exchanger is controlled by different process variables and set points, and is controlled independently of the flow rate of the natural gas feed stream.

According to one aspect of the present disclosure, a natural gas liquefaction system (100) is provided. The system comprises an integrally-geared turbo-compressor (150) with a plurality of compressor stages; a prime mover (160) for driving the compressor; a pre-cooling loop (110), through which a first refrigerant is adapted to circulate, wherein one or more first compressor stages (151) of the plurality of compressor stages are adapted to pressurize the first refrigerant; a cooling loop (130), through which a second refrigerant is adapted to circulate, wherein one or more second compressor stages (155) of the plurality of compressor stages are adapted to pressurize the second refrigerant; a first heat exchanger device (170) for transferring heat from a natural gas and/or from the second refrigerant to the first refrigerant; and a second heat exchanger device (180) for transferring heat from the natural gas to the second refrigerant. A further aspect relates to a compressor arrangement for a natural gas liquefaction system. A yet further aspect relates to a method of liquefying natural gas.

An equipment safety management device for managing safety of equipment capable of holding fluid is provided. The equipment safety management device includes: a safety means configured to be in fluid communication with an outlet of the equipment, the safety means being brought into a released state when pressure of the equipment reaches a previously set pressure, the safety means delivering the fluid to a flare pipe, which is fluidly communicated; and, as the flare pipe, at least one first flare pipe allowing a low-temperature fluid to flow therethrough and at least one second flare pipe allowing an aqueous fluid to flow therethrough. The safety means can deliver the fluid to both the first flare pipe and the second flare pipe.

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 system and method for liquefaction of a natural gas stream utilizing a plurality of asymmetric parallel pre-cooling circuits. The use of asymmetric parallel cooling circuits allows for greater control over each refrigerant stream during the cooling process and simplifies process control by dedicating heat exchangers to performing similar duties.

A system and method for cooling and liquefying a gas in a heat exchanger that includes compressing and cooling a mixed refrigerant using first and last compression and cooling cycles so that high pressure liquid and vapor streams are formed. The high pressure liquid and vapor streams are cooled in the heat exchanger and then expanded so that a primary refrigeration stream is provided in the heat exchanger. The mixed refrigerant is cooled and equilibrated between the first and last compression and cooling cycles so that a pre-cool liquid stream is formed and subcooled in the heat exchanger. The stream is then expanded and passed through the heat exchanger as a pre-cool refrigeration stream. A stream of gas is passed through the heat exchanger in countercurrent heat exchange with the primary refrigeration stream and the pre-cool refrigeration stream so that the gas is cooled. A resulting vapor stream from the primary refrigeration stream passage and a two-phase stream from the pre-cool refrigeration stream passage exit the warm end of the exchanger and are combined and undergo a simultaneous heat and mass transfer operation prior to the first compression and cooling cycle so that a reduced temperature vapor stream is provided to the first stage compressor so as to lower power consumption by the system. Additionally, the warm end of the cooling curve is nearly closed further reducing power consumption. Heavy components of the refrigerant are also kept out of the cold end of the process, reducing the possibility of refrigerant freezing, as well as facilitating a refrigerant management scheme.

A method for operating a main cryogenic heat exchanger for use in a natural gas liquefaction process, involves monitoring or predicting variations in the flow rate of a feed gas stream provided to the main cryogenic heat exchanger. When a variation of the flow rate exceeding a predetermined threshold value is monitored or predicted, a control scheme is started to control one or more compressor recycle valves in response to the monitored or predicted variation of the flow rate to recycle part of a compressed mixed refrigerant stream in a refrigerant loop.

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.

Provided is a gas processing facility capable of enhancing the performance of an air-cooled heat exchanger while suppressing the influence on apparatus from spraying of demineralized water to the air-cooled heat exchanger to be used in a processing of natural gas. An air-cooled heat exchanger arranged in the gas processing facility for performing a liquefaction process of natural gas and the like is configured to supply cooling air to a tube through which a fluid to be cooled is caused to flow, to thereby cool the fluid to be cooled, and a mist supply section is configured to supply mist obtained by spraying demineralized water, to thereby cool the cooling air. Further, the mist supply section is configured to spray the demineralized water from a lateral position on an upstream side of an intake.