Process and plant for the production of liquid hydrogen with a liquefier that has a variable cooling power dependent on the electrical power consumed. The liquefier is supplied with electricity by a first source of electricity at least one additional source of electricity that provides an intermittent or variable amount of electricity over time. Liquid hydrogen is produced at first thermodynamic conditions when the liquefier is supplied with a predetermined nominal electrical energy level and produced at subcooled conditions, with respect to the first thermodynamic conditions, when electricity supplied to the liquefier exceeds the nominal level.

A process for producing liquefied natural gas and liquid carbon dioxide comprising: Step a): separating a natural gas feed gas into a CO.sub.2-enriched gas stream and a CO.sub.2-depleted natural gas stream; Step b): liquefying the CO.sub.2-depleted natural gas stream in a liquefaction unit comprising at least a main heat exchanger and a system for producing frigories, said liquefaction unit comprising at least one refrigeration cycle fed by a refrigerant stream; Step c): simultaneous liquefying of the CO.sub.2-enriched gas stream resulting from step a) in a CO.sub.2 liquefaction unit; wherein the refrigeration necessary for the liquefaction of the CO.sub.2-enriched gas stream and for the liquefaction of the natural gas is supplied by said frigorie-producing system of the liquefaction unit and in that the refrigeration necessary for the liquefaction of the CO.sub.2-enriched gas stream originates from a portion of said refrigerant stream supplying the refrigeration cycle of said liquefaction unit.

A process for producing liquefied natural gas (14) and liquid carbon dioxide (CO.sub.2) (15) comprising at least the following steps: Step a): separating a natural gas feed gas (1), containing hydrocarbons and carbon dioxide in a treatment unit (2), into a CO.sub.2-enriched gas stream (4) and a CO.sub.2-depleted natural gas stream (3); step b): liquefying the CO.sub.2-depleted natural gas stream (3) resulting from step a) in a natural gas liquefaction unit (5) comprising at least a main heat exchanger (8) and a system (9) for producing frigories; step c): simultaneous liquefying of the CO.sub.2-enriched gas stream (4) resulting from step a) in a CO.sub.2 liquefaction unit (6); characterized in that all of the refrigeration necessary for the liquefaction of the CO.sub.2-enriched gas stream (4) and for the liquefaction of the natural gas is supplied by said frigorie-producing system (9) of the natural gas liquefaction unit (5).

A small scale natural gas liquefaction plant is integrated with an LNG loading facility in which natural gas is liquefied using a multi-stage gas expansion cycle. LNG is then loaded onto an LNG truck or other LNG transport vehicle at the loading facility using a differential pressure control system that uses compressed boil off gas as a motive force to move the LNG from the LNG storage tank to the LNG truck so as to avoid the use of an LNG pump and associated equipment as well as to avoid venting of boil off vapors into the environment.

Hydrogen is liquefied through a process utilizing refrigeration from hydrogen at one, two, or three different pressures as well as a nitrogen refrigeration cycle. One or more stages of catalyst are used to convert ortho-hydrogen to para-hydrogen as the hydrogen is cooled and liquefied. Subcooled liquid hydrogen feeds the final stage of ortho-hydrogen to para-hydrogen conversion to reduce or eliminate vaporization of the hydrogen during the exothermic ortho-hydrogen to para-hydrogen conversion.

A cooling system includes a compressor configured to pressurize carbon dioxide to form pressurized carbon dioxide, a mixer configured to generate mixed refrigerant in which the pressurized carbon dioxide and solvent in a liquid state, a depressurization apparatus provided downstream from the mixer and configured to depressurize the mixed refrigerant, a separator configured to separate carbon dioxide in a gas state from the mixed refrigerant, a heat exchanger configured to exchange heat between the mixed refrigerant cooled through depressurization and a fluid to be cooled, and a second heat exchanger configured to cool the carbon dioxide or the mixed refrigerant using vaporized carbon dioxide or the mixed refrigerant.

The invention relates to an integrated process and apparatus for liquefaction of natural gas and recovery of natural gas liquids. In particular, the improved process and apparatus reduces the energy consumption of a Liquefied Natural Gas (LNG) unit by using a portion of the already cooled overhead vapor from a fractionation column from an NGL (natural gas liquefaction) unit to, depending upon composition, provide, for example, reflux for fractionation in the NGL unit and/or a cold feed for the LNG unit, or by cooling, within the NGL unit, a residue gas originating from a fractionation column of the NGL unit and using the resultant cooled residue gas to, depending upon composition, provide, for example, reflux/feed for fractionation in the NGL and/or a cold feed for the LNG unit, thereby reducing the energy consumption of the LNG unit and rendering the process more energy-efficient.

A process for liquefying a natural gas comprising a mixture of hydrocarbons predominating in methane, the process comprising a first semi-open refrigerant cycle with natural gas in which any natural gas liquids that have condensed are separated from the natural gas feed stream, which stream then passes through a main cryogenic heat exchanger (4) in order to contribute by heat exchange to pre-cooling a main natural gas stream (F-P) and to cooling an initial refrigerant gas stream (G-0), a second semi-open refrigerant cycle with natural gas for contributing to pre-cooling the natural gas and the refrigerant and also to liquefying the natural gas, and a closed refrigerant cycle with refrigerant gas for subcooling the liquefied natural gas and for delivering refrigeration power in addition to the other two cycles. The invention also provides a natural gas liquefaction installation for performing such a process.

A method for controlling the flow of natural gas and refrigerant in the main heat exchanger of a natural gas liquefaction facility. The method provides for the automated control of a flow rate of a natural gas feed stream through a heat exchanger based on one or more process variables and set points. The flow rate of refrigerant streams through the heat exchanger is controlled by different process variables and set points, and is controlled independently of the flow rate of the natural gas feed stream.

A method for liquefying a natural gas primarily including methane, preferably at least 85% of methane, the other components essentially including nitrogen and C2-C4 alkanes, in which the natural gas to be liquefied is liquefied by circulating at a pressure P0 no lower than the atmospheric pressure (Patm), P0 preferably being higher than the atmospheric pressure, in at least one cryogenic heat-exchanger (EC1, EC2, EC3) by a counter-current closed-circuit circulation in indirect contact with at least one stream of coolant gas remaining in the compressed gaseous state at a pressure P1 that is entering the cryogenic heat-exchanger at a temperature T3′ that is lower than T3, T3 being the liquefaction temperature of the liquefied natural gas at the pressure P0 at the output of said cryogenic exchanger, characterized in that the coolant gas includes a mixture of nitrogen and at least one other component selected from among neon and hydrogen.