A method for the production of liquefied natural gas and liquid nitrogen is provided. The method may include providing a high pressure natural gas stream, splitting the high pressure natural gas stream into a first portion and a second portion, and liquefying the first portion of the high pressure natural gas stream to produce an LNG stream. The refrigeration needed for cooling and liquefaction of the natural gas and liquefaction of the nitrogen can be provided by a nitrogen refrigeration cycle and letdown of the second portion of the high pressure natural gas stream.

A method for the production of liquefied natural gas (LNG) and nitrogen is provided. The method may include the steps of: a) providing a nitrogen production facility, wherein nitrogen production facility comprises: a main heat exchanger, an air separation unit, a nitrogen recycle compressor, a first nitrogen refrigeration supply configured to provide refrigeration to the main heat exchanger for cooling a main air feed, b) providing a secondary refrigeration supply; c) liquefying a natural gas stream using refrigeration from the secondary refrigeration supply to form an LNG product stream; wherein the secondary refrigeration supply is configured to compress and expand a refrigerant to produce refrigeration, wherein the refrigerant of the secondary refrigeration supply is shared with refrigerant of the first nitrogen refrigeration supply

A method describing the integration of a nitrogen liquefier and letdown of natural gas for the production of liquid nitrogen and lower pressure natural gas is provided. The method may include: providing a nitrogen liquefier having a nitrogen refrigeration cycle, wherein the nitrogen liquefier comprises a nitrogen compressor, a nitrogen recycle compressor, a heat exchanger, and at least a first turbine booster and introducing a nitrogen gas stream to the nitrogen liquefier under conditions effective for liquefying the nitrogen to produce a liquid nitrogen product. The refrigeration needed to liquefy the nitrogen is provided for by the nitrogen refrigeration cycle and letdown of a high pressure natural gas stream.

A method for the integration of a nitrogen liquefier and liquefaction of natural gas for the production of liquefied natural gas and liquid nitrogen is provided. The method may include providing a nitrogen liquefaction unit and providing a natural gas liquefaction unit. Liquefaction of the nitrogen can be achieved via a nitrogen refrigeration cycle within the nitrogen liquefaction unit. Liquefaction of the natural gas can be achieved through the use of natural gas letdown and a second nitrogen refrigeration cycle. The two liquefaction units can be integrated via a common nitrogen recycle compressor, thereby providing significant capital savings.

Variable N2 content in feed gas ranging from 3 mol % to 50 mol % can be rejected from the process using a feed exchanger that is fluidly coupled with a cold separator and a single fractionation column to produce a nitrogen vent stream and streams that are suitable to be further processed for NGL recovery and LNG production.

Embodiments relate generally to systems and methods for operating a natural gas liquids plant in ethane rejection and in ethane recovery. A natural gas liquid plant may comprise an absorber configured to produce an ethane rich bottom stream and an ethane depleted vapor stream; a stripper fluidly coupled to the absorber configured to, during ethane rejection, fractionate the ethane rich bottom stream from the absorber into an ethane overhead product and a propane plus hydrocarbons product, and configured to, during ethane recovery, fractionate the ethane rich bottom stream into an ethane plus NGL stream and an overhead vapor stream; and an exchanger configured to, during ethane recovery, counter-currently contact the ethane rich bottom stream from the absorber with the ethane depleted vapor stream from the absorber, thereby heating the vapor stream and chilling the ethane rich bottom stream before the ethane rich bottom stream is fed to the stripper.

Embodiments relate generally to systems and methods for operating a natural gas liquids plant in ethane rejection and in ethane recovery. A natural gas liquid plant may comprise an absorber configured to produce an ethane rich bottom stream and an ethane depleted vapor stream; a stripper fluidly coupled to the absorber configured to, during ethane rejection, fractionate the ethane rich bottom stream from the absorber into an ethane overhead product and a propane plus hydrocarbons product, and configured to, during ethane recovery, fractionate the ethane rich bottom stream into an ethane plus NGL stream and an overhead vapor stream; and an exchanger configured to, during ethane recovery, counter-currently contact the ethane rich bottom stream from the absorber with the ethane depleted vapor stream from the absorber, thereby heating the vapor stream and chilling the ethane rich bottom stream before the ethane rich bottom stream is fed to the stripper.

The disclosure relates to the technical field of ethane recovery systems, and in particular to an ethane recovery system suitable for a rich gas with high carbon dioxide content and a recovery method therefor. The recovery system includes a first pre-cooling cold box, a second pre-cooling cold box, a subcooling cold box, a low temperature separator, an absorption tower, a tower top separator and a demethanizer. According to the disclosure, freezing and blockage problems occurring in conventional demethanizers when CO.sub.2 content 2 mol % are effectively solved. Meanwhile, an operation pressure of the demethanizer is 300 KPa compared with that of the absorption tower, significantly reducing power consumption of an output compressor, and making an ethane recovery device more energy efficient, and the disclosure is suitable for an ethane recovery device for a medium and high pressure rich gas with high carbon dioxide content.

Described herein are methods and systems for liquefying natural gas by: cooling and liquefying a natural gas feed stream via indirect heat exchange with at least a first cold refrigerant stream to form a first liquefied natural gas stream and a warmed gaseous refrigerant stream; flashing and separating the first liquefied natural gas stream to form a liquefied natural gas product stream and at least a first flash gas stream; combining and compressing the first flash gas stream and the warmed gaseous refrigerant stream to form a compressed refrigerant stream; and expanding at least a first portion of the compressed refrigerant stream to form the first cold refrigerant stream; wherein the natural gas feed stream is kept separate from and is not combined with either the first flash gas stream or the compressed refrigerant stream.

The present application belongs to the field of environmental protection, and in particular to a system and method for simultaneously producing high-purity liquid nitrogen and high-purity liquid carbon dioxide at low cost by using flue gas. The system provided by the present application comprises a flue gas boosting and cooling system, a CO.sub.2/N.sub.2 front-end separation system, a liquid CO.sub.2 preparation system and a high-purity liquid nitrogen preparation system The present application can maximize the use of flue gas to produce high-purity liquid nitrogen and liquid CO.sub.2 at low cost, and realize the synchronous resource utilization of carbon/nitrogen components.