The present invention comprises systems and methods for natural gas liquefaction. In embodiments, the systems comprise a dual turbo-expander, methane-based refrigeration system that also uses a slip stream of LNG for additional cooling.

A system and a method for producing liquefied natural gas are provided. The system includes a refrigeration loop system for providing a cold stream of refrigerant, a supersonic chiller for receiving and chilling a first gaseous natural gas stream to produce a liquefied natural gas liquid and separating the liquefied natural gas liquid from the first gaseous natural gas stream to obtain a second gaseous natural gas stream, and a cold box for receiving the cold stream of refrigerant and the second gaseous natural gas stream and cooling the second gaseous natural gas stream to obtain a liquefied natural gas by heat exchanging between the second gaseous natural gas stream and the cold stream of refrigerant.

A natural gas liquefying apparatus is provided. At least a part of a cooling region, in which a precooling unit and a liquefaction unit are arranged, and at least a part of a compression region, in which first and second compressors compressing refrigerants to be used in the precooling unit and the liquefaction unit are arranged, are arranged to be opposed to each other across a long side of a second refrigerant cooler group arrangement region in which a liquefying refrigerant is cooled. A first refrigerant cooler group arrangement region, in which a precooling refrigerant is cooled, is arranged so that a long side of the first refrigerant cooler group arrangement region is opposed to one side of a rectangular region including the compression region, the one side being different from a side of the rectangular region opposed to a long side of the second refrigerant cooler group arrangement region.

Compressed rich natural gas is divided into a cooling gas stream and a fuel gas stream. The cooling gas stream is depressurized. The cooling gas and the fuel gas are then heat exchanged to provide a first cooling step to the fuel gas. The cooled fuel gas continues into a second cooling step in a second heat exchanger, and then flows into a separator vessel where liquids are removed from the bottom of the separator and conditioned fuel gas exits the top of the separator. The conditioned fuel gas from the separator and produced from its influent is depressurized and heat exchanged to provide the second cooling fluid for the second heat exchanger.

A system and method for power generation and CO.sub.2 sequestration include a fuel cell system configured to generate power using natural gas (NG), a container configured to store liquid natural gas (LNG), and a fluid processor configured to convert LNG received from the container into NG and to convert exhaust output from the fuel cell system to dry ice by transferring heat between and the LNG and the exhaust.

A method and system for liquefying a methane-rich high-pressure feed gas stream using a first heat exchanger zone and a second heat exchanger zone. The feed gas stream is mixed with a refrigerant stream to form a second gas stream, which is compressed, cooled, and directed to a second heat exchanger zone to be additionally cooled below ambient temperature. It is then expanded to a pressure less than 2,000 psia and no greater than the pressure to which the second gas stream was compressed, and then separated into a first expanded refrigerant stream and a chilled gas stream. The first expanded refrigerant stream is expanded and then passed through the first heat exchanger zone such that it has a temperature that is cooler, by at least 5° F., than the highest fluid temperature within the first heat exchanger zone.

A system and method for producing liquefied natural gas (LNG) from a natural gas stream. Each of a plurality of LNG trains liquefies a portion of the natural gas stream to generate a warm LNG stream in a first operating mode, and a cold LNG stream in a second operating mode. A sub-cooling unit is configured to, in the first operating mode, sub-cool the warm LNG streams generated by each of the plurality of LNG trains to thereby generate a plurality of cold LNG streams. The warm LNG streams have a higher temperature than a temperature of the cold LNG streams in the second operating mode and the plurality of cold LNG streams. The combined flow rate of the plurality of cold LNG streams has, in the first operating mode, a higher flow rate than the combined flow rate of the cold LNG streams in the second operating mode.

Systems and processes for natural gas processing, liquefaction, and storage are described. The systems and processes include one or more arrangements of features which are capable of liquefying all of the gas entering an inlet of the system or a portion of the entering gas. The portion of the entering gas that is liquefied can vary based on the pressure of an outlet of the system, which can be fixed or vary based on usage downstream.

Described herein are methods and systems for the liquefaction of a natural gas stream using a refrigerant comprising methane or a mixture of methane and nitrogen. The methods and systems use a refrigeration circuit and cycle that employs one or more turbo-expanders to expand one or more streams of gaseous refrigerant to provide one or more streams of at least predominantly gaseous refrigerant that are used to provide refrigeration for liquefying and/or precooling the natural gas, and a J-T valve to expand down to a lower pressure a stream of liquid or two-phase refrigerant to provide a vaporizing stream of refrigerant that provides refrigeration for sub-cooling.

Compression train for a natural gas liquefaction process. The compression train includes a driver machine and only one centrifugal compressor machine driven in rotation by the driver machine; the compressor is configured to compress a refrigerant gas with a molecular weight less than 30 g/mol from a suction pressure to a discharge pressure; the ratio between discharge and suction pressures is higher than 10. A LNG plant including a compression train.