An air separation plant is provided that includes a plurality of air compressors, a plurality of air purification units, and one or more cold boxes. In a first mode of operation, a first air compressor is configured to compress air to a higher pressure than a second air compressor. In a second mode of operation, the second air compressor is configured to compress air to a higher pressure than during the first mode of operation.

The invention relates to an installation for producing liquefied hydrogen having a gaseous hydrogen generator configured to produce gaseous hydrogen, a liquefier, a supply duct connecting a gaseous hydrogen outlet of the gaseous hydrogen generator to an inlet of the liquefier, the liquefier having a refrigerator having a cycle circuit configured to provide cooling power and cool the gaseous hydrogen from the supply duct with a view to the liquefaction thereof, the installation having at least one compressor for the gaseous hydrogen produced by the gaseous hydrogen generator and a buffer store configured to store the compressed gaseous hydrogen between the gaseous hydrogen generator and the liquefier, the buffer store being connected to the supply duct via a set of bypass duct(s), i.e. the buffer store and the liquefier are connected in parallel to the gaseous hydrogen outlet of the gaseous hydrogen generator.

Described herein are methods and systems for removing natural gas liquids from a natural gas feed stream and for liquefying the natural gas feed stream so as to produce a liquefied natural gas (LNG) stream and a natural gas liquids (NGL) stream.

Methods and systems include, using a monitoring system, initiating a control logic configured to control a production control system pertaining to a refrigeration system connected to a plurality of production trains. The method may include obtaining a plurality of production parameters; calculating, using the plurality of production parameters, an isentropic efficiency value for the primary compressor if the production flow rate is less than a production threshold; comparing each of the plurality of isentropic efficiency values; determining from the comparing each of the plurality of isentropic efficiency values, a primary compressor having a lowest isentropic efficiency value; selecting the respective primary compressor having the lowest isentropic efficiency value. The method may include, using a production control system, shutting down the selected primary compressor.

A process for producing liquid nitrogen utilizes a distillation system comprising higher-pressure and lower-pressure columns, a first condenser in the lower-pressure column bottom, and a second condenser disposed on top of the lower-pressure column. Feed air is compressed in a main air compressor above 15 bar(a) and cooled in a main heat exchanger. A first cooled air portion is expanded in a cold turbine before separation in the higher-pressure column. A second cooled air portion is liquefied before entering the higher-pressure column. Liquid nitrogen streams condensed by both the first and second condensers are combined to yield the final product. Another feature involves warming and expanding a lost air stream (e.g., from the cold turbine outlet and/or higher-pressure column) to below 2 bar(a) in a warm turbine.

Methods and systems providing a process for cooling and liquefying a purified gaseous hydrogen feed stream to a liquid hydrogen stream that may be stored in a liquid hydrogen storage tank, as well as a system wherein ortho-hydrogen (o-H2) contained in the purified gaseous hydrogen feed stream may be converted to para-hydrogen (p-H2) through serial low-temperature catalytic converters along the cooling process from normal ambient temperature (300K) to the liquefied temperature about (20K) of the hydrogen.

A method for controlling flow in a Natural Gas Liquids (NGL) extraction system includes determining an operational characteristic of one or more residue gas compressors operating within the NGL extraction system and calculating a rate of closure for one or more throttle valves associated with the one or more residue gas compressors based on the operational characteristic determined. When a process upset in the NGL extraction system is detected, the one or more throttle valves are closed at the calculated rate of closure in response to detecting the process upset.

A method for separating hydrogen and nitrogen from a gas mixture, including a) thereby partially condensing a hydrogen and nitrogen gas mixture and producing a two-phase stream, b) phase separating the two-phase stream, producing a nitrogen-enriched liquid fraction and a hydrogen-enriched gaseous fraction, c) expanding the nitrogen-enriched liquid fraction, producing a lower-pressure nitrogen-enriched liquid or two-phase stream, d) adding heat to the lower-pressure nitrogen-enriched liquid stream, producing a warm nitrogen enriched gaseous stream, and e) adding heat to the hydrogen-enriched gaseous fraction, producing a hydrogen-rich product stream. Wherein, at least a portion of the heat added in step d) is removed in step a), at least a portion of the heat added in step e) is removed in step a), or at least a portion of the heat added in step d) and at least a portion of the heat added in step e) is removed in step a).