Plant and method for producing liquefied hydrogen

Abstract

The invention relates to a plant and a method for producing liquefied hydrogen comprising a hydrogen gas generator, a liquefier, a feed line connecting an outlet of the hydrogen gas generator to an inlet of the liquefier, the liquefier comprising a refrigerator having a cycle circuit to cool the hydrogen gas from the feed line, the plant comprising a buffer store configured to store the compressed hydrogen gas between the hydrogen gas generator and the liquefier, the liquefier being configured to supply a cooling power and/or the liquefaction capacity that can be modified between at least two levels, the plant comprising a means for determining the fill level of the buffer store, the plant being configured to modify the cooling power and/or liquefaction capacity of the liquefier as a function of the fill level of the buffer store determined by the determining means.

1 . A plant for producing liquefied hydrogen the plant comprising:
 a hydrogen gas generator, for example an electrolyzer, configured to produce hydrogen gas,   a liquefier,   a feed line connecting a hydrogen gas outlet of the hydrogen gas generator to an inlet of the liquefier,   wherein the liquefier further comprises a refrigerator having a cycle circuit configured to supply the cooling power and cool the hydrogen gas from the feed line,   a buffer store configured to store the compressed hydrogen gas between the hydrogen gas generator and the liquefier, the liquefier being configured to supply a cooling power and/or the liquefaction capacity that can be modified between at least two levels,   a means for determining the fill level of the buffer store,   wherein the plant is configured to modify the cooling power and/or liquefaction capacity of the liquefier as a function of the fill level of the buffer store determined by the means for determining the fill level,   wherein the plant is further configured to modify the cooling power and/or the liquefaction capacity of the liquefier as a function of the fill level of the buffer store determined by the means for determining after a given delay.   
     
     
         2 . The plant as claimed in  claim 1 , wherein the means for determining the fill level of the buffer store is configured to determine the fill level of the buffer store from a plurality of predefined fill levels, and wherein the plant is configured to establish the cooling power and/or the liquefaction capacity of the liquefier at specific levels corresponding respectively to the fill levels of the predefined buffer store. 
     
     
         3 . The plant as claimed in  claim 1 , wherein the plant is configured to relatively reduce the cooling power and/or the liquefaction capacity of the liquefier when the fill level of the buffer store decreases. 
     
     
         4 . The plant as claimed in  claim 1 , wherein the plant is configured to relatively increase the cooling power and/or the liquefaction capacity of the liquefier when the fill level of the buffer store increases. 
     
     
         5 . The plant as claimed in  claim 1 , wherein the means for determining the fill level of the buffer store comprises a pressure sensor. 
     
     
         6 . The plant as claimed in  claim 1 , wherein the pressure sensor is configured to measure the pressure in the buffer store and/or in a line connected to an outlet of the buffer store. 
     
     
         7 . The plant as claimed in  claim 1 , wherein the liquefier comprises a refrigerator with a cycle circuit in which a cycle gas flow is subjected to a given thermodynamic cycle, the plant being configured to modify the cooling power and/or liquefaction capacity of the liquefier by modifying the flow rate and/or quantity of cycle gas in the cycle circuit. 
     
     
         8 . The plant as claimed in  claim 1 , wherein the plant is configured to decrease the cooling power and/or liquefaction capacity of the liquefier by decreasing the flow rate and/or the quantity of cycle gas in the cycle circuit via at least one of the following: a cycle gas discharge line to the feed line, a cycle gas discharge line to a discharge zone, a means for liquefying at least a portion of the cycle gas in the cycle circuit. 
     
     
         9 . The plant as claimed in  claim 1 , wherein the liquefier comprises a refrigerator with a cycle circuit in which a cycle gas flow is subjected to a given thermodynamic cycle comprising a compression and an expansion, the plant being configured to modify the cooling power and/or liquefaction capacity of the liquefier by modifying the pressure level of the compression of the cycle gas in the cycle circuit. 
     
     
         10 . The plant as claimed in  claim 1 , wherein the liquefier comprises several independent refrigerators with a cycle circuit each configured to supply the respective cooling power for cooling hydrogen gas from the feed line with a view to the liquefaction thereof, and in that the plant is configured to modify the cooling power and/or liquefaction capacity of the liquefier by differentially modifying the cooling power and/or liquefaction capacity of the various refrigerators. 
     
     
         11 . The plant as claimed in  claim 1 , wherein the means for determining the fill level of the buffer store comprises a programmable electronic means for storing and processing data comprising a microprocessor, the means for determining the fill level being configured to receive operating data from the hydrogen gas generator and/or consumption data of the liquid hydrogen produced by the liquefier, and to use this data to predict a future fill level of the buffer store in a future time interval, for example between one and twenty-four hours, the plant being configured to modify the cooling power and/or liquefaction capacity of the liquefier as a function of the future fill level of the buffer store determined by the determining means. 
     
     
         12 . The plant as claimed in  claim 1 , wherein the hydrogen gas generator comprises an intermittent electrical supply supplied by a renewable energy source, for example solar, and in that the means for determining the fill level is configured to receive weather forecast data and to predict, including from this data, the future fill level of the buffer store. 
     
     
         13 . A method for producing liquefied hydrogen using a plant, the method comprising the steps of:
 providing the plant as claimed in  claim 1 ;   determining the fill level of the buffer store; and   regulating the cooling power and/or liquefaction capacity of the liquefier as a function of the determined fill level of the buffer store.   
     
     
         14 . The method as claimed in  claim 13 , wherein the determination of the fill level of the buffer store is measured, and/or estimated and/or predicted from operating data from the plant, which includes: hydrogen production capacity per hydrogen gas generator, historical hydrogen production capacity per hydrogen gas generator, meteorological data, current and future consumption of liquid hydrogen produced by the liquefier. 
     
     
         15 . The method as claimed in  claim 13 , wherein the step of regulating the cooling power and/or liquefaction capacity of the liquefier comprises a modification of the cooling power and/or liquefaction capacity of the liquefier which is performed in response to a change in the fill level of the buffer store, the modification of the cooling power and/or liquefaction capacity being carried out concomitantly and/or before and/or after the change in the determined fill level of the buffer store. 
     
     
         16 . The method as claimed in  claim 13 , wherein the liquefier comprises a refrigerator having a cycle circuit in which a cycle gas flow is subjected to a given thermodynamic cycle, the step of regulating the cooling power and/or the liquefaction capacity of the liquefier comprising at least one of the following: a modification of the flow rate and/or the quantity of cycle gas in the cycle circuit, for example a discharge of cycle gas from the cycle circuit, a decrease in the quantity of gas in the cycle circuit by partial liquefaction of the cycle gas in a separator vessel, a modification of the pressure of the compression of the cycle gas in the cycle circuit. 
     
     
         17 . The method as claimed in  claim 13 , further comprising a step of stopping the plant in which the liquefier is stopped, followed by a step of restarting the plant and the liquefier, the method comprising, after restarting and before a step of regulating the cooling power and/or liquefaction capacity of the liquefier, a given delay, for example between two and twelve hours, and/or a delay until the fill level of the buffer store reaches a predetermined threshold.