A thermodynamic system containing a working fluid is disclosed. The thermodynamic system comprises at least a working fluid collection vessel (11) adapted to contain a liquid phase and a gaseous phase of the working fluid in thermodynamic equilibrium. A chilling arrangement (51) is functionally coupled to the fluid collection vessel (11) and adapted to remove heat from the working fluid collected in the working fluid collection vessel (11) and thereby reduce pressure in said thermodynamic system. Also disclosed are methods for depressurizing a thermodynamic system containing a working fluid in liquid/gas equilibrium.

A method for turndown of a liquefied natural gas (LNG) plant, the plant including a liquefaction unit arranged in a flow path of the plant, includes removing LNG from a first location in the flow path downstream of the liquefaction unit; vaporizing the removed LNG, or heating the removed LNG so that the removed LNG is transformed to gas phase; and re-admitting the vaporized or transformed LNG to the flow path at a second location upstream of the liquefaction unit. A corresponding LNG plant is also provided.

Disclosed is a liquefied natural gas production train, comprising at least one integrated process unit having a structural frame forming multiple process equipment floors. The at least one integrated process unit extends in vertical direction, wherein a height of the at least one integrated process unit is substantially equal to or larger than a width and a length of the at least one integrated process unit. The disclosure also provides a method of producing liquefied natural gas, using the LNG production train.

An arrangement comprising at least one liquefaction plant for liquefying a gaseous medium to produce a liquefied medium; and at least one storage tank for storing the liquefied medium. A first transfer line is provided which is connected between the liquefaction plant and the storage tank, for transferring liquefied medium from the liquefaction plant into the storage tank. A second transfer line is connected between the liquefaction plant and the storage tank, for transferring gaseous medium from the storage tank into the liquefaction plant. The second transfer line, which used for transferring medium from the storage tank into the liquefaction plant, is arranged so that it is routed at least partially through the area of the storage tank in which the liquefied medium is stored in use.

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.

There is provided a system and method for producing liquefied natural gas (LNG). An exemplary method includes flowing a high-pressure stream of LNG through a first series of liquid turbines. The exemplary method also includes generating electricity by reducing the pressure of the high-pressure stream of LNG to form a low-pressure stream of LNG. The exemplary method additionally includes bypassing any one the liquid turbines that has a failure while continuing to produce electricity from the first series.

A method of cooling a process stream with an auxiliary stream is described, wherein the exchange of heat between the process stream and the auxiliary stream is effected in a first heat exchanger and a second heat exchanger connected downstream thereof.

Disclosed is a boil-off gas reliquefaction system for vessels. The BOG reliquefaction system for vessels includes: a multistage compressor compressing BOG; a heat exchanger cooling the BOG compressed by the multistage compressor through heat exchange using BOG not compressed by the multistage compressor as a refrigerant; a pressure reducer disposed downstream of the heat exchanger and decompressing a fluid cooled by the heat exchanger; and a bypass line through which BOG is supplied to the multistage compressor after bypassing the heat exchanger.

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.

Systems and methods for operating a natural gas liquids (NGL) plant can include obtaining upstream flow volumes, input flows, and operating conditions of a refinery complex including the NGL plant for a first time period and a second time period. One or more features can be extracted from the upstream flow volumes, input flows, and operating conditions for multiple first time periods and used to form multiple feature vectors. A machine learning model trained with labeled data (e.g., labeled data associating upstream flow volumes, input flows, and operating conditions with incoming feed gas volumes) representing incoming feed gas of the NGL can be used to process the feature vectors to determine predicted incoming feed gas volumes.