A system and method for providing supplemental refrigeration to an air separation plant is provided. A closed loop supplemental refrigeration circuit that can be easily retrofitted or added onto an air separation plant that increases the liquid product production capability of the air separation plant. The supplemental refrigeration capacity of the supplemental refrigeration circuit is controlled by removing or adding a portion of the refrigerant in the supplemental refrigeration circuit to adjust the inlet pressure while maintaining a substantially constant volumetric flow rate and substantially constant pressure ratio across the compressor. Removing the refrigerant from the supplemental refrigeration circuit decreases the refrigeration imparted by the supplemental refrigeration circuit and thus provides the capacity to turn-down liquid product make without shutting down the compressors and turbo-expanders in the supplemental refrigeration circuit.

A method for the production of liquefied natural gas (LNG) using a cold fluid provided from a cryogenic unit, such as an air separation unit or nitrogen liquefier, is provided. The method may include the steps of: withdrawing a nitrogen stream from a cryogenic unit, wherein the nitrogen stream is at a temperature between about 155 C. to about 193 C.; and liquefying a natural gas stream in a natural gas liquefaction unit using the nitrogen stream from the cryogenic unit.

A method of supplying refrigeration to air separation plants within an air separation plant facility in which a refrigerant stream is produced at cryogenic temperature within a centralized refrigeration system. Streams of the refrigerant at the cryogenic temperature are introduced into the air separation plants such that all or a part of the refrigeration requirements of the air separation plants are supplied by the streams of the refrigerant.

A method for producing an air product in an air separation plant. Feed air is cooled at least in a main air compressor and is fed into a distillation column system. A fluid storage unit and a cold accumulator are used. In a first operating mode, fluid is stored in the fluid storage unit and the cold accumulator is heated. In a third operating mode, fluid is released and the cold accumulator is cooled, and in a second operating mode, fluid is neither stored nor released.

An air product is produced in an air separation plant having a heat exchanger, an expansion/compression unit, a rectification unit, liquid storage, cold storage and an air compressor. The air supplied to the rectification unit is conducted through the main air compressor at a pressure level at least 3 bar above the highest operation pressure for the rectification unit. Cryogenic liquids are produced in a first production amount by a first operating mode, a lower second production amount by a second operating mode and a higher third production amount by a third operating mode. Cryogenic liquid is stored in the liquid storage in the third operating mode and removed from storage in the second operating mode. Cryogenic liquid is evaporated in different amounts in each operating mode, which amounts differ by no more than 10%.

A method of supplying refrigeration to air separation plants within an air separation plant facility in which a refrigerant stream is produced at cryogenic temperature within a centralized refrigeration system. Streams of the refrigerant at the cryogenic temperature are introduced into the air separation plants such that all or a part of the refrigeration requirements of the air separation plants are supplied by the streams of the refrigerant.

A method for separating air is provided, in which a flow of oxygen-rich liquid is sent to a top of a pure oxygen column, having a pure oxygen reboiler, in which said flow is purified in order to form a vessel liquid containing at least 98 mol % of oxygen and the vessel liquid is drawn off as a product. A supercharged airflow at a second pressure is sent to the pure oxygen reboiler and to a liquid oxygen vaporizer; a nitrogen-rich gas is drawn from the top of the medium-pressure column and sent to an intermediate reboiler of the low-pressure column and the condensed gas is sent to the top of the medium-pressure column; and a nitrogen-rich gas or air is sent to a vessel reboiler of the low-pressure column and the liquid that condenses therein is sent to the medium-pressure column.

A system and method for providing supplemental refrigeration to an air separation plant is provided. A closed loop supplemental refrigeration circuit that can be easily retrofitted or added onto an air separation plant that increases the liquid product production capability of the air separation plant. The supplemental refrigeration capacity of the supplemental refrigeration circuit is controlled by removing or adding a portion of the refrigerant in the supplemental refrigeration circuit to adjust the inlet pressure while maintaining a substantially constant volumetric flow rate and substantially constant pressure ratio across the compressor. Removing the refrigerant from the supplemental refrigeration circuit decreases the refrigeration imparted by the supplemental refrigeration circuit and thus provides the capacity to turn-down liquid product make without shutting down the compressors and turbo-expanders in the supplemental refrigeration circuit.

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 for converting excess liquid oxygen into liquid nitrogen, including introducing a gaseous nitrogen stream into a main heat exchanger, therein exchanging heat with a vaporized oxygen stream, a vapor phase nitrogen steam, and a waste liquid nitrogen stream; thereby producing a cold gaseous nitrogen stream, an oxygen vent stream, a nitrogen vent steam, and a gaseous nitrogen waste stream, introducing the cold gaseous nitrogen stream into a secondary heat exchanger, therein exchanging heat with a liquid oxygen stream; thereby producing the vaporized oxygen stream and a cold liquid nitrogen stream, introducing the cold liquid nitrogen stream into a nitrogen pressure reduction valve thereby producing a two-phase nitrogen stream, introducing the two-phase nitrogen stream into a nitrogen flash vessel thereby producing a liquid phase nitrogen stream and the vapor phase nitrogen stream, wherein the method is performed in the absence of refrigerant turbo-expanders, refrigerant expansion turbines, or refrigerant compressors.