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) passing the first warmer refrigerant stream through an entry port located in a second zone of the heat exchanger that is warmer than the first zone (d) passing an oil-containing refrigerant stream through an entry port located in a second zone of the heat exchanger that is warmer than the first zone; (e) mixing the first warmer refrigerant stream and the oil-containing stream in the heat-exchanger to form a combined refrigerant stream; and (f) passing the combined refrigerant stream out of the heat exchanger through the warmer exit port.

Integration of a natural gas liquefaction system, a hydrogen production system, and power generation system to increase CO2 capture and improve overall plant efficiency. The predominantly methane endflash is sent to the hydrogen production system which produces hydrogen and CO2. The CO2 may be captured or beneficially used. At least a portion of the hydrogen produced is used to fuel gas turbines in the power generation which, in turn, provides power for the refrigeration compressor of the natural gas liquefaction system—either in the form of mechanical work or electricity.

A module for a natural gas liquefaction apparatus is provided to include air-cooled heat exchanger groups and another equipment group. The air-cooled heat exchanger groups another equipment group. The air-cooled heat exchanger groups are arranged side by side on an upper surface of a structure, and are each configured to cool a fluid handled in the natural gas liquefaction apparatus. The another equipment group is arranged on a lower side from an arrangement height of each air-cooled heat exchanger groups, and forms a part of the natural gas liquefaction apparatus. When equipment groups are classified into a pretreatment unit equipment group provided in a pretreatment unit configured to perform pretreatment of natural gas before being liquefied, and a liquefaction processing unit equipment group provided in a liquefaction processing unit associated with processing of liquefying the natural gas after being treated in the pretreatment unit, the another equipment group is formed of the pretreatment unit equipment group.

A drive system for liquefied natural gas (LNG) refrigeration compressors in a LNG liquefaction plant. Each of three refrigeration compression strings include refrigeration compressors and a multi-shaft gas turbine capable of non-synchronous operation. The multi-shaft gas turbine is operationally connected to the refrigeration compressors and is configured to drive the one or more refrigeration compressors. The multi-shaft gas turbine uses its inherent speed turndown range to start the one or more refrigeration compressors from rest, bring the one or more refrigeration compressors up to an operating rotational speed, and adjust compressor operating points to maximize efficiency of the one or more refrigeration compressors, without assistance from electrical motors with drive-through capability and variable frequency drives.

A compressor system is disclosed, including a first compressor unit having: at least a first gas inlet at a first gas pressure level; a second gas inlet at a second gas pressure level; and a gas discharge; a second compressor unit having: at least a third gas inlet at a third gas pressure level; a fourth gas inlet at a fourth gas pressure level; and a gas delivery. The gas discharge of the first compressor unit is fluidly coupled to one of the third gas inlet and fourth gas inlet of the second compressor unit.

Provided is a method of designing a heat exchanger group being installed in a processing plant and having multiple ACHEs. In a first step, at least one design variable relating to ACHE design and the number of installed ACHEs are set as variable parameters, and a variable range and a change unit of each of the variable parameters are set. In a second step, a design value of the ACHE, which includes a value of a design variable non-selected as the variable parameter, is set. In a third step, Pareto solutions for at least two objective functions selected from an objective function group consisting of an installation length of the heat exchanger group, a total heat transfer area of heat transfer tubes, and total power consumption of fans are calculated by using a computer while the variable parameter are changed.

A method to control the cooldown of main heat exchangers in liquefied natural gas plant. 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.

The present invention relates to a method of controlling the production of a liquefied natural gas product stream (31) obtained by removing heat from natural gas by indirect heat exchange with an expanded heavy mixed refrigerant and an expanded light mixed refrigerant. The method comprises executing a control loop comprising maintaining the flow rate of the liquefied natural gas product stream (31) at a dependent set point and maintaining the flow rates of the heavy mixed refrigerant (60a) and the light mixed refrigerant (65) at operator manipulated set points (80, 81). The method further comprises executing an override control loop comprising: determining an override set point (95′) for the flow rate of the liquefied natural gas and computing an override set point (80′) for the flow rate of the heavy mixed refrigerant and an override set point (81′) to reduce residual available power of the electric motor.

The present invention relates to a method and apparatus for cooling down a cryogenic heat exchanger adapted to liquefy a hydrocarbon stream, such as a natural gas stream. The method comprises: (i) receiving one or more refrigerant temperature indications, providing an indication of the temperature of the refrigerant, (ii) comparing the one or more refrigerant temperature indications with one or more associated predetermined threshold values, and (iii) based on the outcome of the comparison under (ii) selecting one of an automated warm cooling down procedure of the cryogenic heat exchanger and an automated cold cooling down procedure of the cryogenic heat exchanger.

A drive system for liquefied natural gas (LNG) production. A standardized machinery string consisting of a multi-shaft gas turbine with no more than three compressor bodies, where the compressor bodies are applied to one or more refrigerant compressors employed in one or more refrigerant cycles (e.g., single mixed refrigerant, propane precooled mixed refrigerant, dual mixed refrigerant). The standardized machinery strings and associated standardized refrigerators are designed for a generic range of feed gas composition and ambient temperature conditions and are installed in opportunistic liquefaction plants without substantial reengineering and modifications. The approach captures D1BM (“Design 1 Build Many) cost and schedule efficiencies by allowing for broader variability in liquefaction efficiency with location and feed gas composition.