Described herein is a method of removing refrigerant from a natural gas liquefaction system in which vaporized mixed refrigerant is withdrawn from the closed-loop refrigeration circuit and introduced into a distillation column so as to be separated into an overhead vapor enriched in methane and a bottoms liquid enriched in heavier components. Overhead vapor is withdrawn from the distillation column to form a methane enriched stream that is removed from the liquefaction system, and bottoms liquid is reintroduced from the distillation column into the closed-loop refrigeration circuit. Also described are methods of altering the rate of production in a natural gas liquefaction system in which refrigerant is removed as described above, and a natural gas liquefaction systems in which such methods can be carried out.

A system and method is provided for efficiently managing the compression of gas depending on the operating conditions and operating mode of the compression system, wherein the system includes a booster compressor, a booster compressor bypass, a conduit connected to the booster compressor and the booster compressor bypass conduit, a means for selectively directing the flow of the gas based on current operating conditions, to the booster compressor bypass or the booster compressor and a baseline compressor connected to both the booster compressor and the booster compressor bypass conduit.

Liquefier arrangements configured for co-production of both liquid natural gas (LNG) and liquid nitrogen (LIN) configured to operate in two distinct operating modes are provided.

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.

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.

Liquefier arrangements configured for flexible co-production of both liquid natural gas (LNG) and liquid nitrogen (LIN) are provided. Each liquefier arrangement comprises separate and independent nitrogen recycle circuits or loops, including a warm recycle circuit and a cold recycle circuit with a means for diverting nitrogen refrigerant between the two recycle circuits or loops. The warm recycle circuit includes a booster loaded warm turbine, a warm booster compressor and warm recycle compression whereas the cold recycle circuit includes a booster loaded cold turbine, a cold booster compressor and a separate cold recycle compression.

An installation and method for purifying and liquefying natural gas having, arranged in series, an adsorption purification unit, a unit for separating hydrocarbons by refrigeration, and a liquefier. The installation has a gas power plant for combined production of heat and electricity by hydrocarbon combustion. The installation has at least one electrical member, with the power plant being electrically connected to at least one of the electrical members in order to supply them with electrical energy.

Liquefier arrangements configured for co-production of both liquid natural gas (LNG) and liquid nitrogen (LIN) configured to operate in two distinct operating modes are provided.

An LNG plant comprises a cold box and a refrigeration unit fluidly coupled with a plurality of heat exchanger passes in the cold box. The refrigeration unit is configured to provide a first refrigerant stream to a first heat exchanger pass of the plurality of heat exchanger passes at a first pressure, a second refrigerant stream to a second heat exchanger pass at a second pressure, and a third refrigerant stream to a third heat exchanger pass at a third pressure. The second refrigerant stream comprises a first portion of the first refrigerant stream, and the third refrigerant stream comprises a second portion of the first refrigerant stream. The second pressure and the third pressure are both below the first pressure. The cold box is configured to produce LNG from a natural gas feed stream to the cold box using a refrigeration content from the refrigeration unit.

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.