A system for the production of liquefied natural gas from raw natural gas. The system includes a pre-treatment module to remove impurities from a raw natural gas input, a gas compression module to compress gas received from the pre-treatment module, an absorption chiller for providing gas equipment cooling in the compression module, and a gas liquefaction module including a gas pre-cooler configured to pre-cool gas received from the compression module using a closed-loop refrigeration cycle and a six-stream heat exchanger unit configured to cool gas received from the gas pre-cooler. A power module is provided that powers the pre-treatment module, gas compression module, and gas liquefaction module.

An inlet air cooling system used in a gas turbine for supplying power to a refrigerant compressor for compressing refrigerant in a natural gas liquefaction plant includes: an inlet air cooler for cooling inlet air of the gas turbine; chiller motors used for a chiller for cooling coolant supplied to the inlet air cooler; a first variable speed driver for supplying electric power to each of the one or more chiller motors; and an electric generator driven by the gas turbine, wherein the electric generator is electrically connected to the first variable speed driver, and electric power generated by the electric generator can be supplied to each of the chiller motors from the first variable speed driver without using a main power line of an electric power system, which enables efficient electric power supply to the motors via the variable speed driver.

Provided are an apparatus and method for liquefying natural gas. The apparatus for liquefying natural gas includes a gas compressor configured to receive and compress the natural gas from a natural gas feed stream, a heat exchanging unit configured to cool a high-pressure natural gas passing through the gas compressor through heat exchange, an expansion valve configured to expand the cooled natural gas passing through the heat exchanging unit, a hold-up drum configured to phase-separate a gas-liquid mixture produced by passing through the expansion valve and divide the gas-liquid mixture into a liquefied natural gas and a cryogenic recycle gas having nitrogen content greater than that of the liquefied natural gas so as to discharge the liquefied natural gas and the cryogenic recycle gas, and a bypass line configured to provide the recycle gas discharged from the hold-up drum to the heat exchanging unit.

An embodiment of a method for supplying refrigerants to a liquefied natural gas (LNG) facility includes: advancing a first refrigerant from a first storage device to a heat exchanger, the first refrigerant having a first temperature; advancing a second refrigerant from a second storage device to the heat exchanger, the second refrigerant having a second temperature different than the first temperature; flowing the first refrigerant and the second refrigerant through the heat exchanger; adjusting the second temperature based on at least a transfer of heat between the first refrigerant and the second refrigerant in the heat exchanger; and transferring the first refrigerant and the second refrigerant to the LNG facility.

Systems and methods are provided for the production of liquefied natural gas. At least one of the systems may include a plurality of compression assemblies in fluid communication with a precooler assembly. One compression assembly may be a part of a precooling loop and may include at least one compressor driven by a variable or fixed speed motor. Another compression assembly may be part of a liquefaction loop and may include at least one pair of compressors, each compressor driven by a respective turbine. The liquefaction loop may be fluidly coupled to a main heat exchanger utilized to liquefy at least a portion of a feed gas stream containing natural gas flowing through the main heat exchanger, thereby producing liquefied natural gas.

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.

Provided is a method of constructing a natural gas liquefaction plant, which can shorten a construction time period by minimizing effect of a lead time for the refrigerant compressor thereon, the method including: transporting a refrigerant compression module body 175 to an installation area 85, wherein the refrigerant compression module body is provided with a frame 120 configured to allow refrigerant compressor 150 for compressing a refrigerant for cooling natural gas to be mounted therein; installing the refrigerant compression module body 175 to the installation area 85; and mounting the refrigerant compressor 150 into a mounting space 130 predefined in the frame 120 of the installed refrigerant compression module body.

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 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 liquefed, 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 split mixed refrigerant (MR) natural gas liquefication system, where low-pressure (LP) and medium pressure (MP) MR compressors are driven by a first gas turbine and a propane compressor and a high-pressure (HP) MR compressor is driven by a second gas turbine, is disclosed. The split MR liquefication system is configured to adjust the characteristics of the HP MR compressor to require less power when less power is available and more power when more power is available compared to the system's design point. Such adjustments allow for shifting the balance of power between the propane compressor and the HP MR compressor to improve LNG production efficiency.