INSTALLATION POUR LA PRODUCTION DE H2

The present invention relates to an installation for the production of dihydrogen comprising:          a reaction enclosure (1) intended to contain an oxidizable material,     an alkaline solution feed system (2) fluidly connected to the reaction enclosure (1),     a pure water (31) supply system (3) fluidly connected to the reaction enclosure (1),     a dihydrogen collection system (4) downstream of the reaction enclosure (1), the collection system (4) being fluidly connected:           to the reaction enclosure (1),       to the supply system (3), and to       a storage receptacle (5) configured to store the produced dihydrogen at a desired high pressure.

FIELD OF THE INVENTION

The present invention relates to the general technical field of the production of dihydrogen H2, more commonly called “hydrogen”.

In particular, the invention relates to an installation (and an associated method) for producing hydrogen under pressure by a chemical reaction, in particular by decomposition of water under the action of metals or metalloids.

BACKGROUND OF THE INVENTION

Hydrogen can be used in various applications due to its high energy potential. It can be converted into electricity, heat or motive power depending on the end use.

Not existing naturally, it must be manufactured from a primary energy source, then transported, stored and distributed to the user.

2. Existing Hydrogen Production Methods

Today, hydrogen can be produced from hydrocarbons by steam reforming of natural gas or by gasification of petroleum residues or coal. A disadvantage of hydrogen production methods by steam reforming is that they involve fossil resources.

Other methods for producing hydrogen, for example by electrolysis or by photocatalysis, have already been proposed. However, a disadvantage of these methods is that the hydrogen is produced under a relatively low pressure—typically comprised between 1 and 30 bars, so that a step of compressing the hydrogen is necessary to allow its loading into storage reservoirs. Moreover, these methods, and in particular electrolysis, are very energy-intensive.

Finally, methods for producing hydrogen using metals that decompose water under the action of an acid or a base are also known. In particular, document US 2003/0143155 discloses a method for producing hydrogen by corrosion of aluminum in water. This method includes the steps consisting of:introducing an aqueous solution containing sodium hydroxide into a reaction receptacle,introducing aluminum particles into the aqueous solution,maintaining the aluminum particles on the surface of the aqueous solution,reacting the aluminum particles with the water in the aqueous solution to produce hydrogen,maintaining the amount of sodium hydroxide in the reaction receptacle substantially constant, andobtaining an alumina precipitate in the bottom of the reaction receptacle.

A disadvantage of the method according to US 2003/0143155 relates to its significant production cost.

Indeed, when a reaction between aluminum and water is initiated, an impermeable alumina layer forms on the surface of the aluminum, and protects it from corrosion. This has the effect of slowing down or even stopping the corrosion reaction of the aluminum. It is therefore necessary to dissolve this alumina layer using an aqueous solution having a high pH, that is to say a high alkali concentration.

Thus, to implement the method described in document US 2003/0143155, the concentration of sodium hydroxide in the aqueous solution must be high. Therefore, the precipitation of alumina in the bottom of the reaction receptacle mentioned in US 2003/0143155, and the regeneration of sodium hydroxide which follows are limited. This results in consumption of sodium hydroxide during the aluminum corrosion reaction, and thus the need to regularly add sodium hydroxide to the reaction receptacle to maintain the aluminum corrosion reaction, which increases the cost of producing hydrogen from the method according to US 2003/0143155.

3. Purpose of the Invention

A purpose of the present invention is to propose an installation (and its associated method) for producing hydrogen allowing to overcome at least one of the aforementioned disadvantages.

In particular, a purpose of the present invention is to propose an installation configured to produce hydrogen under pressure, treat it, and fill a storage receptacle (such as a bottle) under pressure.

Another purpose of the present invention is to propose a hydrogen production installation to facilitate the management of reaction by-products.

Another purpose of the present invention is to provide an installation and a hydrogen production method allowing to obtain lower hydrogen production costs than those of the installations and methods of the prior art.

BRIEF DESCRIPTION OF THE INVENTION

To this end, the invention proposes an installation for the production of dihydrogen comprising:a reaction enclosure intended to contain an oxidizable material,an alkaline solution feed system fluidly connected to the reaction enclosure,a pure water supply system fluidly connected to the reaction enclosure,a dihydrogen collection system downstream of the reaction enclosure, the collection system being fluidly connected:on the one hand to the reaction enclosure, andon the other hand to the supply system, and comprising a terminal for connecting a storage receptacle to the installation, said receptacle being configured to store the dihydrogen produced at a desired high pressure greater than or equal to 60 bars, preferably greater than 150 bars, even more preferably greater than 250 bars, in particular of the order of 350 bars,
remarkable in that the reaction enclosure comprises:a reaction chamber in which a corrosion reaction of the oxidizable material by the alkaline solution is carried out, said reaction producing a gas containing dihydrogen, and a reaction fluid composed of a mixture of alkaline solution and oxidized material,a settling chamber in which a precipitation reaction of the oxidized material contained in the reaction fluid is carried out, anda stirring unit fluidly connected to the reaction chamber and to the settling chamber to ensure the circulation of the reaction fluid between the reaction chamber and the settling chamber, the speed of circulation of the reaction fluid in the reaction chamber being greater than the speed of circulation of the reaction fluid in the settling chamber.

The fact that the reaction enclosure includes:two separate chambers, namely:a first chamber—called a “reaction chamber”—in which the corrosion reaction of the oxidizable material (for example aluminum) is carried out, anda second chamber—called a “settling chamber”—in which the precipitation reaction of the oxidized material (for example sodium aluminate) is carried out, anda stirring unit for ensuring the circulation of the reaction fluid through the first and second chambers, the speed of circulation of the reaction fluid in the first chamber (“reaction chamber”) being greater than the speed of circulation of the reaction fluid in the second chamber (“settling chamber”),
allows on the one hand to attack the oxidizable material with an alkaline aqueous solution having a high pH ensuring the initiation and maintenance of the corrosion reaction of the oxidizable material with the water contained in the alkaline aqueous solution, and on the other hand to ensure precipitation of the oxidized material mainly in the settling chamber, that is to say in a compartment different from that in which the corrosion reaction takes place.

This arrangement ensures precipitation (for example in the form of alumina) of all the oxidized material produced (for example sodium aluminate), and therefore regeneration of the alkaline aqueous solution before its passage through the reaction chamber.

The device according to the invention thus allows the production of hydrogen without it being necessary to add alkali (such as sodium hydroxide (soda), potassium hydroxide (potash), lithium hydroxide, ammonium hydroxide (ammonia), etc.) during the corrosion reaction of the oxidizable material, which reduces the costs of producing hydrogen.

Preferred but non-limiting aspects of the device according to the invention are the following:the power of the pump, the dimensions of the reaction chamber and the dimensions of the settling chamber can be configured so that:the circulation speed of the reaction fluid is greater than or equal to 5 cm/s in the reaction chamber, preferably greater than or equal to 6 cm/s, andthe circulation speed of the reaction fluid is less than or equal to 4 cm/s in the settling chamber, preferably less than 3 cm/s;the settling chamber may comprise a cyclone separation system;the collection system can be fluidly connected to the reaction chamber of the reaction enclosure to receive the gas produced by the corrosion reaction of the oxidizable material, said collection system comprising a heat exchanger for condensing the water vapor contained in said gases and forming condensed pure water;the collection system may further comprise a liquid sensor and a safety valve mounted between the reaction enclosure and the heat exchanger, the safety valve being:in a passing state when no liquid is detected by the liquid sensor so as to allow the circulation of gases between the reaction enclosure and the collection system,in a blocked state when a liquid is detected by the liquid sensor so as to prevent the circulation of gases from the reaction enclosure to the heat exchanger;the collection system may further comprise a purifier mounted downstream of the heat exchanger to treat the gases coming from the heat exchanger;the collection system may further comprise a spillway downstream of the heat exchanger, said spillway allowing the circulation of gases towards the storage receptacle when the pressure in the collection system is greater than or equal to the desired high pressure;the collection system may comprise an isolation valve, said isolation valve being:in a blocked state:when the storage receptacle needs to be replaced, orduring a start-up phase of the installation in which the reaction enclosure is filled with the alkaline solution,otherwise in a passing state;the pure water supply system may comprise a tank containing pure water, and a transfer pump between said tank and the reaction enclosure, said transfer pump being configured to:transfer pure water from the tank to the reaction enclosure during a phase of recovery of dihydrogen contained in a gas pocket located in the reaction enclosure, between the alkaline aqueous solution and the gas collection system,transfer said pure water at a pressure greater than or equal to the desired high pressure;the tank can be at atmospheric pressure, the supply system comprising a degassing valve, said degassing valve being:in a blocked state during the corrosion reaction of the oxidizable material by the alkaline solution, said reaction producing a gas containing dihydrogen,in a passing state when the corrosion reaction is completed, to reduce the pressure inside the reaction enclosure and inside the collection system;the supply system may further comprise:an inlet valve between the collection system and the tank, said inlet valve being:in a blocked state during the corrosion reaction of the oxidizable material by the alkaline solution, so that the condensed pure water from the heat exchanger is redirected to the reaction enclosure,in a passing state when the corrosion reaction is completed, to allow the circulation of condensed pure water from the heat exchanger, from the collection system to the tank, andan outlet valve between the tank and the reaction enclosure, said outlet valve being in a passing state when the corrosion reaction is complete, for rinsing by-products of the corrosion reaction.

The invention also relates to a method for producing dihydrogen from an installation comprising:a reaction enclosure intended to contain an oxidizable material, said enclosure including:a reaction chamber in which a corrosion reaction of the oxidizable material is carried out, said reaction producing a gas containing dihydrogen, and a reaction fluid containing oxidized material, anda settling chamber in which a reaction of precipitation of the oxidized material contained in the reaction fluid is carried out,an alkaline solution feed system fluidly connected to the reaction enclosure,a pure water supply system fluidly connected to the reaction enclosure,a dihydrogen collection system downstream of the reaction enclosure, the collection system being fluidly connected to the reaction enclosure, and to the supply system, the collection system comprising a terminal for connecting a storage receptacle configured to store the dihydrogen produced at a desired high pressure greater than or equal to 60 bars, preferably greater than 150 bars, even more preferably greater than 250 bars, in particular of the order of 350 bars,remarkable in that the method comprises a step of stirring the reaction fluid to ensure the circulation of the reaction fluid:at a first circulation speed in the reaction chamber, andat a second circulation speed in the settling chamber,the second circulation speed being lower than the first circulation speed.

DETAILED DESCRIPTION OF THE INVENTION

Different examples of embodiment of the invention will now be described with reference to the figures. In these different figures, the equivalent elements are designated by the same numerical reference.

1. General Presentation

With reference toFIG.1, the installation is made up of different groups each having a specific function in the context of hydrogen production.

In particular, the installation comprises:a reaction enclosure1,an alkaline aqueous solution feed system2upstream of the reaction enclosure,a pure water supply system3downstream of the alkaline aqueous solution feed system,a hydrogen collection system4downstream of the reaction enclosure,a control unit (not shown) to control the different components of the reaction enclosure1, the feed system2, the supply system3and the collection system4.

The reaction enclosure1allows the implementation of a corrosion reaction of an oxidizable material with the water contained in the alkaline aqueous solution.

The alkaline aqueous solution feed system2allows:to inject the alkaline aqueous solution into the reaction enclosure1at the start of the reaction in order to fill the reaction enclosure with the alkaline aqueous solution, andto extract the alkaline aqueous solution contained in the reaction enclosure1at the end of the reaction in order to empty the reaction enclosure1.

The pure water supply system3allows to inject pure water into the reaction enclosure1at the end of the reaction in order to:to limit the losses of hydrogen produced (elimination of a gaseous sky contained in the reaction enclosure at the end of the reaction), and/orto rinse the by-products formed following the corrosion reaction of the oxidizable material with water.

The collection system4allows:on the one hand to filter the outlet gases from the reaction enclosure in order to separate the water vapor from the hydrogen contained in the outlet gas from the reaction enclosure, andon the other hand to convey the hydrogen to a receptacle5(such as a bottle) for its storage.

The oxidizable material may be selected from a metal—such as magnesium or silicon or aluminum—or a metal alloy—such as an alloy 1050 or an alloy 4032 or an alloy 4043 or an alloy 6060 or an alloy 2017 (or any other metal alloy known to the person skilled in the art). This allows to limit the costs of producing hydrogen. Of course, other oxidizable materials known to the person skilled in the art can also be used. In the following, the invention will be presented with reference to the use of aluminum as an oxidizable material, it being understood that the device and the method according to the invention are not limited to the use of aluminum to produce hydrogen.

“Alkaline aqueous solution” means, in the context of the invention, an aqueous solution whose pH is greater than 7. This alkaline aqueous solution is for example composed of pure water and one (or more) alkali(s).

The alkali(s) may for example be selected from sodium hydroxide (soda), potassium hydroxide (potash), lithium hydroxide, ammonium hydroxide (ammonia).

Advantageously, when the oxidizable material consists of Magnesium or one of its alloys, sodium chloride and/or potassium chloride can be used instead of the alkali (or alkalis).

In the following, the invention will be presented with reference to the use of sodium hydroxide, it being understood that the device and the method according to the invention are not limited to the use of sodium hydroxide to produce hydrogen.

In the context of the invention, “pure water” is defined as water containing water molecules H2O, and possibly traces of mineral salts. Thus, in the context of the invention, distilled water or demineralized water is considered to be pure water, in the same way as osmosis water.

With reference toFIG.2, the reaction enclosure1is configured to contain the reagents, namely:aluminum11(oxidizable material),the alkaline aqueous solution composed of water and sodium hydroxide (alkali).

It is suitable for withstanding pressures greater than 30 bars, in particular greater than 60 bars. In particular, the reaction enclosure is adapted to withstand pressures greater than 150 bars, preferably greater than 200 bars, and even more preferably greater than 350 bars. Moreover, the reaction enclosure1is configured to resist corrosion. Finally, the corrosion reaction of the aluminum11being exothermic, the reaction enclosure1is configured to withstand temperatures greater than or equal to 200° C. To meet these different constraints, the material constituting the reaction enclosure1can be Nickel, or a Nickel alloy.

The corrosion reaction of aluminum11with water in the presence of sodium hydroxide induces the production of aluminum oxides and hydroxides. The reaction enclosure1is configured to cause the precipitation of these aluminum oxides and hydroxides in the form of aluminates12, and to contain these aluminates12.

For this purpose, the reaction enclosure1comprises first and second gas-tight chambers C1, C2:the first chamber C1—called the “reaction chamber”—delimits a zone in which the corrosion reaction of the aluminum11by the alkaline aqueous solution is carried out,the second chamber C2—called the “settling chamber”—delimits a zone in which the aluminum oxides and hydroxides precipitate in the form of aluminates12.

In the embodiment illustrated inFIG.2, the reaction chamber C1is mounted on the settling chamber C2. In particular, the reaction C1and settling C2chambers are produced in a single cylindrical housing composed of a bottom, an upper cover and a side wall between the bottom and the cover. The integration of the reaction C1and settling C2chambers in the same housing allows to limit the risks of leaks related to a sealing failure in the reaction enclosure1. This also allows to limit the bulk of the reaction enclosure1. Advantageously, the reaction chamber C1can be located above the settling chamber C2(along a vertical axis A-A′). This allows to avoid the circulation of aluminates in the reaction chamber once they have precipitated: the aluminates are deposited in the settling chamber C2, for example at a removable reservoir to facilitate their extraction from the reaction enclosure1at the end of the reaction.

Alternatively, the reaction C1and settling C2chambers can be produced in distinct and separate housings, said housings being connected via pipelines to allow the circulation of the reaction fluid between the reaction C1and settling C2chambers. This allows in particular to use reaction C1and settling C2chambers of different shapes and dimensions. This also allows to reduce the height of the reaction enclosure1.

Advantageously, the reaction chamber C1may comprise a heat accumulator14extending over the side wall(s) of the reaction chamber C1. This allows to limit the risks of an increase in temperature in the reaction enclosure1beyond 250° C.

Indeed, such a heat accumulator14is capable of:absorbing the energy dissipated in the form of heat during the corrosion reaction of aluminum11, in particular when the temperature in the reaction chamber C1increases and reaches a temperature threshold,restoring in the form of heat the energy absorbed when the temperature in the reaction chamber C1decreases below the temperature threshold.

Thus, the heat accumulator14allows:to store thermal energy during the corrosion reaction of the aluminum11with water in order to limit the heating of the walls of the reaction enclosure1, andto return it later.

In certain variant embodiments, the heat accumulator14may comprise:a partition intended to be in thermal contact with the side wall(s) of the reaction chamber C1, the partition including a lower panel, an upper panel and a pair of side panels between the lower and upper panels,a phase change material (or PCM) contained in the partition.

PCM is a material capable of changing physical state (solid/liquid) within a restricted temperature range (for example between 200° C. and 250° C.). Thus, PCM has the particularity of going from the liquid state to the solid state at a temperature close to 200° C. The solidification reaction (that is to say transition from the liquid state) to the solid state is exothermic. The liquefaction reaction (transition from the solid state to the liquid state) is endothermic. The integration of such a heat accumulator14therefore allows better control of the temperature inside the reaction enclosure1.

The reaction enclosure1also comprises a stirring unit to promote the circulation of the reaction fluid between the reaction chamber C1and the settling chamber C2.

In the embodiment illustrated inFIG.2, the stirring unit consists of a centrifugal pump P1connected to the reaction chamber C1and to the settling chamber C2via a circulation channel15. In particular, the centrifugal pump P1is arranged so as to:pump the reaction fluid into an upper part of the reaction chamber C1, and toinject the reaction fluid thus pumped into an upper part of the settling chamber C2.

For this purpose, the reaction chamber C1comprises a first tubular access member disposed in its upper part (that is to say closer to the cover of the housing than the grid of the housing), and the settling chamber C2comprises a second tubular access member disposed in its upper part (that is to say closer to the grid of the housing than to the bottom of the housing). The centrifugal pump P1is connected to the reaction C1and settling C2chambers so as to:suck up the reaction fluid contained in the reaction chamber C1at the first access member, anddischarge the reaction fluid into the settling chamber at the second access member.

Alternatively, the stirring unit may consist of a propeller including a shaft and two (or four) blades at one end of the shaft, the other end of the shaft being connected to a motor to induce the rotation of the propeller shaft and blades. In this case, the propeller is directly immersed in the housing, between the reaction C1and settling C2chambers.

Advantageously, the dimensions of the reaction C1and settling C2chambers as well as the characteristics of the stirring unit are selected so that:the speed of circulation of the reaction fluid in the reaction chamber C1is comprised between 5 and 15 cm/s, preferably 6 and 15 cm/s, and even more preferably between 6 and 10 cm/s,the speed of circulation of the reaction fluid in the settling chamber is comprised between 0.1 and 4 cm/s, preferably 1 and 3 cm/s, and even more preferably between 2 and 3 cm/s.

The fact that, in the reaction chamber C1, the circulation speed of the reaction fluid is greater than or equal to 5 cm/s (preferably greater than or equal to 6 cm/s) allows to promote the evacuation of the by-products of the corrosion reaction of the aluminum outside the reaction chamber (and therefore limits the risk of slowing down the corrosion reaction due to the alumina).

The fact that, in the settling chamber C2, the circulation speed of the reaction fluid is less than or equal to 4 cm/s (preferably less than or equal to 3 cm/s) allows:on the one hand to promote the precipitation of the sodium aluminate formed during the aluminum corrosion reaction, andon the other hand, to promote the separation (by settling) of the solid particles (alumina) contained in the reaction fluid; the solid particles12thus separated are advantageously collected in a base of the settling chamber C2.

To obtain different circulation speeds between the reaction chamber and the settling chamber (and in particular speeds of the order of 6 cm/s in the reaction chamber and 3 cm/s in the settling chamber), the diameter of the reaction chamber can be reduced relative to the diameter of the settling chamber (in the case of cylindrical chambers).

This reduction in diameter in the reaction chamber can be obtained:either by local reduction of the diameter of the reaction enclosure housing,either by inserting an insert into the housing (for example PTFE insert of cylindrical shape including a through channel of reduced diameter extending along its axis of revolution).

In certain embodiments, the settling chamber C2may comprise a cyclone (or hydrocyclone) separation system to promote the separation of the reaction fluid from the solid particles it contains. Such a cyclone separation system (not shown) is known to the person skilled in the art and will not be described in more detail below.

Optionally, a cooling unit can be mounted on the walls of the settling chamber C2to reduce the temperature of the reaction fluid. This allows to promote the precipitation of aluminum oxides and hydroxides contained in the reaction fluid in the form of aluminates12.

The reaction enclosure1comprises an oxidizable material support for carrying the oxidizable material. In the embodiment illustrated inFIG.2, the support consists of a grid13separating the reaction chamber C1and the settling chamber C2, and the through openings of which allow the passage of the reaction fluid between the settling chamber C2and the reaction chamber C1. In other embodiments, the oxidizable material support may consist of a removable pillar, one of the ends of which rests on the bottom of the housing, and the free end of which extends into the reaction chamber, at the interface between the reaction chamber C1and the settling chamber C2.

Advantageously, the reaction enclosure may comprise a filling sensor16placed between the reaction chamber C1and the collection system4. The filling sensor16allows to detect the presence of alkaline aqueous solution. Its positioning allows to indicate, to the control unit, the instant at which the maximum volume of alkaline aqueous solution that the reaction enclosure1can contain is reached, in particular when filling the reaction enclosure1with the alkaline aqueous solution21, as will be described in more detail below.

3. Alkaline Aqueous Solution Feed System

With reference toFIG.3, the feed system2is configured to:fill the reaction enclosure1with the alkaline aqueous solution21at the start of the reaction, and tostore the alkaline aqueous solution21at the end of the reaction.

The alkaline aqueous solution21may comprise water mixed with sodium hydroxide (NaOH) or potassium hydroxide (KOH) with a concentration between 0.5% and 20%.

The feed system2comprises a tank22adapted to contain the alkaline aqueous solution21. This tank22can have different shapes and be made of different materials capable of resisting corrosion (such as Nickel or a Nickel alloy).

The tank22is brought to atmospheric pressure via a vent opening23formed in the upper wall of the tank22. This opening23allows to avoid the formation of a depression in the tank22when the alkaline aqueous solution21is injected into the reaction enclosure1at the start of the reaction. The opening23also allows the filling of the tank22with the alkaline aqueous solution, as will be described in more detail below.

The feed system2also comprises one (or more) conduit(s)24allowing fluid communication between the tank22and the reaction enclosure1. Each conduit24can be associated with an electrically controllable circulation valve25(that is to say solenoid valve) to authorize (when the circulation valve25is in an open state) or prevent (when the circulation valve25is in a closed state) the passage of the alkaline aqueous solution21between the tank22and the reaction enclosure1. This ensures:filling the reaction enclosure1with the alkaline aqueous solution21at the start of the reaction,draining the reaction enclosure1of the alkaline aqueous solution21at the end of the reaction.

In the embodiment illustrated inFIG.3, the feed system2comprises first, second and third conduits24a,24b,24cassociated respectively with first, second and third circulation valves25a,25b,25c:the first conduit24a(associated with the first circulation valve25a) allows the passage of the alkaline aqueous solution from the reaction enclosure1to the tank22; this first conduit24aallows the reaction enclosure1to be drained at the end of the reaction,the second conduit24b(associated with the second circulation valve25b) allows the passage of the alkaline aqueous solution from the tank22to the reaction enclosure1; this second conduit24ballows the reaction enclosure1to be filled at the start of the reaction,the third conduit24c(associated with the third circulation valve25c) allows the purge of the various tubes of the installation when filling the reaction enclosure1.

With reference toFIG.3, the feed system2does not have a circulation pump. Indeed, in this embodiment, it is the centrifugal pump P1—forming stirring unit of the reaction enclosure1—which ensures the movement of the alkaline aqueous solution21through the conduit(s)24:between the tank22and the reaction enclosure1at the start of the reaction, andbetween the reaction enclosure1and the tank22at the end of the reaction.

Alternatively, the feed system2may include a pump—for example of the peristaltic pump or roller pump type—for circulating the alkaline aqueous solution21between the tank22and the reaction enclosure1.

Of course, the feed system2may comprise other components known to the person skilled in the art such as:a safety valve26to limit the risk of overpressure in the tank22,a hatch (not shown) for the introduction of sodium hydroxide or potassium hydroxide, for example packaged in the form of pellets,a purge hole (not shown) to empty the alkaline aqueous solution21contained in the tank22, etc.

4. Pure Water Supply System

With reference toFIG.4, the supply system3is configured to:inject pure water into the reaction enclosure1at the end of the reaction:in order to eliminate a gaseous sky formed above the reaction fluid during the corrosion reaction of the oxidizable material, and/orin order to rinse the residual oxidizable material remaining at the end of the reaction, and/orin order to rinse the aluminates12(solid by-products) separated from the reaction fluid and collected in the base of the settling chamber,recover pure water31from the collection system4during the filtering of the gases produced in the reaction enclosure1during the aluminum corrosion reaction.

The supply system3comprises a tank32configured to contain the pure water31. This tank32can have different shapes and be made of different materials such as steel, aluminum or plastic.

The tank32is brought to atmospheric pressure via an vent lumen33. This lumen33allows to avoid the formation of a depression in the tank32when the pure water31is injected into the reaction enclosure1, or of an overpressure in the tank when pure water is introduced therein.

The supply system3also comprises one (or more) pipe(s)34allowing fluid communication of the tank32with the reaction enclosure1, each pipe34being associated with an electrically controllable valve35to authorize or not the passage of pure water31through said pipe34.

In the embodiment illustrated inFIG.4, the supply system3comprises an inlet valve35adisposed between the tank32and the collection system4, and an outlet valve35bbetween the tank32and the reaction enclosure1:when the inlet valve35ais in a passing state (and the outlet valve35bis in a non-passing state), it allows the passage of pure water (obtained by condensation as will be explained in more detail below) between the collection system4and the tank32to fill the latter;when the outlet valve35bis in a passing state (and the inlet valve35ais in a non-passing state), it allows the passage of pure water between the tank32and the settling chamber of the reaction enclosure, either to compensate for a loss of liquid during the corrosion reaction, or to rinse the by-products at the end of the reaction.

Optionally, the supply system3can also include a high pressure transfer pump36to ensure the movement of pure water31between the tank32and the reaction enclosure1.

Injecting pure water31into the reaction enclosure1allows:during the corrosion reaction, to compensate for the loss of water from the reaction fluid,at the end of the corrosion reaction, to minimize hydrogen losses by “pushing” the gaseous sky towards the collection system4,after the corrosion reaction and the draining of the reaction fluid in the tank22, to rinse the elements contained in the reaction enclosure (remaining aluminum11, aluminates12, etc.).

Advantageously, the supply system3can comprise a degassing valve37to allow the pressure inside the reaction enclosure1to be gradually reduced at the end of the reaction, and in particular to return the installation to atmospheric pressure when all the oxidizable material has been consumed.

Of course, the supply system3may comprise other components known to the person skilled in the art such as:a non-return valve on the (or some) pipe(s),a filling hole to introduce pure water into the installation,a drainage system, etc.

5. Gas Collection System

With reference toFIG.5, the gas collection system is configured to:recover the gases generated during the corrosion reaction of aluminum11,filter said gases to separate the hydrogen from the other compounds contained in the gases generated,connect the installation to a storage reservoir for the hydrogen produced during the corrosion reaction.

In particular, the collection system4is adapted to:cool the gases generated in the reaction enclosure1,condense the water vapor contained in said gases, and return the pure water thus condensed:in the reaction enclosure1during the implementation of the corrosion reaction (hydrogen production step), orin the tank32of the supply system3at the end of the reaction.

For filtering the gases generated by the corrosion reaction of the aluminum11, the collection system comprises a heat exchanger41to cool the gases generated in order to extract the water vapor.

The heat exchanger41is configured to withstand high pressures (pressures greater than 30 bars, in particular greater than 60 bars, preferably greater than 150 bars, more preferably greater than 250 bars and even more preferably greater than 350 bars), and high temperatures (temperatures greater than or equal to 200° C., in particular greater than or equal to 250° C.). The heat exchanger41is for example of the air-cooled type.

For example, the heat exchanger41may comprise:a coil (not shown) inside which the gases coming from the reaction enclosure1circulate, the external faces of the walls of the coil including cooling fins,a blower (not shown)—such as a fan—can promote heat exchange between the gases circulating in the coil and the outside air.

Alternatively, the heat exchanger41can be of the heat transfer fluid cooling type.

The collection system4also comprises a temperature sensor42in communication with the control unit (not shown) of the installation, the control unit activating the heat exchanger41when the temperature measured by the temperature sensor42is greater than a predefined threshold value (for example 50° C.).

The heat exchanger41allows to condense the water vapor contained in the gases leaving the reaction enclosure1to form pure liquid water. This pure liquid water (or condensate) is separated from the hydrogen using a condensate separator48placed at the outlet of the heat exchanger41.

During the corrosion reaction, the pure liquid water is reintroduced into the reaction chamber C1of the reaction enclosure1. At the end of the corrosion reaction, the pure water is reintroduced into the tank32of the supply system3.

For this purpose, the heat exchanger41is in fluid communication—via one (or more) pipeline(s)—with the reaction enclosure1on the one hand, and with the supply system3on the other hand, one (or more) controlled orientation valve(s) (for example one (or more) solenoid valve(s)) arranged along the pipeline(s) allowing to direct the circulation of the condensed water to the reaction enclosure1or to the supply system3.

Optionally, the collection system4may comprise a liquid sensor43and a controlled safety valve44downstream of the heat exchanger41. The liquid sensor43and the safety valve44are configured to communicate with the control unit.

In particular:the liquid sensor43allows to detect the presence of corrosive liquid downstream of the heat exchanger41; when a corrosive liquid is detected by the liquid sensor43, it transmits a signal to the installation control unit,the safety valve44allows to open or close a passage to the storage receptacle5of the hydrogen produced:if a corrosive liquid is detected by the liquid sensor43, the control unit controls the closing of the safety valve44to prevent the propagation of said corrosive liquid towards the storage receptacle5,if no corrosive liquid is detected by the liquid sensor43, the control unit controls the opening of the safety valve44to allow the passage of gases to the storage receptacle5.

The presence of a liquid sensor43associated with a safety valve44the opening and closing of which are controlled by the controller allows to limit the risks of degradation of the storage receptacle with corrosive liquid.

To allow the circulation of gases between the heat exchanger41and the storage receptacle5, the collection system4comprises a gas circulation conduit45connected to the heat exchanger41on the one hand and to the storage receptacle5on the other hand.

However, before being stored in the storage receptacle5, the hydrogen must be treated to have a given purity and/or a given humidity level which depend on the technical specifications of the storage receptacle5and/or the intended application. This is why the collection system4comprises a gas purifier46mounted along the gas circulation conduit45between the heat exchanger41and the storage receptacle5. This purifier46can contain a desiccant product (silica gel type, CaO, CaCl2or others), and/or an activated carbon, and/or a particle filter, and/or a hydrophobic membrane, and/or a palladium membrane, etc.

Advantageously, the collection system4may include a discharger47(or pressure reducer) mounted along the gas circulation conduit45. This discharger47allows to regulate the pressure of the gas in the collection system4in order to make it correspond to the desired pressure for the storage receptacle5(for example storage of hydrogen at a pressure of 150 bars, or 200 bars, or 350 bars, etc.).

Finally, the collection system4may include an isolation valve48downstream of the purifier46to (manually or automatically) open/close the passage between the purifier46and the storage receptacle5. This allows to close the gas circulation conduit45in order to disconnect the storage receptacle when it is full and replace it with an empty storage receptacle.

6. Principle of Operation

The principle of operation of the hydrogen production installation will now be described with reference toFIGS.6ato6d.

A first phase of the hydrogen production method relates to the preparation of the installation, and in particular its loading for the implementation of the corrosion reaction.

6.1.1. Formulation of the Alkaline Aqueous Solution

When the installation has not yet been used, a first step in the preparation phase relates to the formulation of the alkaline aqueous solution. For this purpose:the tank22of the feed system is filled with pure water, for example through the vent opening23, andsodium hydroxide (for example packaged in the form of one or more pellets) is introduced into the tank22, for example through the opening23.

Pure water and sodium hydroxide are mixed to form the alkaline aqueous solution.

When implementing the formulation step, the first and second circulation valves25a,25bare in a closed state to maintain the alkaline aqueous solution in the tank22.

Advantageously, the formulation step is only implemented once during the first use of the installation, the alkaline aqueous solution being reusable at the end of the corrosion reaction.

6.1.2. Pure Water Supply

The preparation phase also comprises a step of supplying pure water in the tank32of the supply system.

This step of supplying pure water may consist of:completely filling the tank with pure water when the installation has not been used, oradding pure water to the tank32to upgrade the amount of pure water contained in the tank in the event of reuse of the installation.

Whether it is the first filling or an upgrade, pure water can be introduced into the supply system at the lumen33formed in the upper wall of the tank32.

6.1.3. Inserting the Consumable

The preparation phase also comprises a step of loading the enclosure with the oxidizable material (aluminum, etc.) necessary for the formation of hydrogen.

The oxidizable material may have the shape of a block. It is introduced into the reaction chamber C1and placed on the support of the reaction enclosure1to allow it to be maintained in position during the corrosion reaction carried out subsequently.

With reference toFIG.6b, a second phase of the method relates to the corrosion reaction. This corrosion reaction phase is broken down into different steps:a start-up step in which the different reagents are mixed in the reaction enclosure1,a hydrogen generation step composed of a transient regime and a quasi-stationary regime succeeding the transient regime,a finishing step during which different actions are implemented in particular for the recovery of hydrogen, and/or the rinsing of reaction by-products.

To initiate the corrosion reaction, the different reagents are mixed in the reaction enclosure1which contains the oxidizable material.

Particularly during the start-up step, the reaction enclosure1is filled with the alkaline aqueous solution21. For this purpose, the second circulation valve25bis switched to a passing state to allow the circulation of the alkaline aqueous solution21from the tank22towards the reaction enclosure1. The movement of the alkaline aqueous solution21can be ensured by any means known to the person skilled in the art (gravity, activation of a pump, etc.). In the embodiment illustrated inFIG.6b, the movement of the alkaline aqueous solution is ensured by the activation of the centrifugal pump P1. During the sub-step of filling the reaction enclosure1with the alkaline aqueous solution21, the circulation valves25a,25care occasionally opened (passing state) to expel the air contained in the different lines (that is to say circulation channel15, conduits24, etc.) of the reaction enclosure1and the supply system3. Moreover, during the filling sub-step, the isolation valve48is closed (non-passing state) to prevent the air contained in the installation from entering the storage receptacle5intended to contain the hydrogen produced. When the filling sensor16detects the presence of alkaline aqueous solution21, then the reaction enclosure1is completely filled: the maximum volume of alkaline aqueous solution21that the reaction enclosure1can contain is reached. The filling sensor16emits a signal to the control unit which controls the closing of the second circulation valve25b(switching to a non-passing state) to prevent the circulation of the aqueous solution between the tank22and the reaction enclosure1.

Once the reaction enclosure is completely filled with the alkaline aqueous solution, the corrosion reaction starts and hydrogen is produced: the isolation valve48is opened (either manually or automatically by the control unit) to allow the circulation of the hydrogen produced between the collection system4and the storage receptacle5.

6.2.2. Hydrogen Generation

The corrosion reaction of the oxidizable material begins: hydrogen is continuously generated, the reaction solution circulates in the reaction enclosure1between the reaction C1and settling C2chambers.

The pressure and temperature in the reaction enclosure1gradually increase. When the pressure in the reaction enclosure1(and in the gas collection system4) reaches the desired pressure for the storage receptacle5(for example 150 bars, 200 bars, 250 bars, 300 bars or 350 bars), the discharger47opens and allows the hydrogen to circulate in the gas purifier46and then in the storage receptacle5.

At the outlet of the gas purifier46, the hydrogen is dry:on the one hand due to the fact that the residual humidity contained in the gases leaving the heat exchanger41is expelled by the humidity absorber contained in the purifier, andon the other hand due to the fact that the amount of water vapor in the gas for a given temperature is determined by the ratio of the partial pressures of the gas and the water vapor for this temperature, while the partial pressure of the vapor water depends only on temperature; thus, at high gas pressure (for example 200 atmospheres) and relatively low temperature (for example 50 degrees Celsius), the partial pressure of water vapor will be low (˜0.12 bar or 0.06% of the partial pressure of hydrogen); it is concluded that the hydrogen leaving the gas purifier46contains a very small amount of water vapor: 0.06% water vapor and 99.94% hydrogen.

During the corrosion reaction of aluminum11with the alkaline aqueous solution21, hydrogen, aluminum oxides and aluminum hydroxides are produced in the reaction chamber C1. The hydrogen escapes to the gas collection system4, while the aluminum oxides and hydroxides are transported in the reaction fluid to the settling chamber C2where they precipitate in the form of aluminates12. The hydrogen which is evacuated towards the collection system4is saturated with water vapor and has a very high temperature. As it passes through the heat exchanger, the hydrogen is cooled (to approximately 60° C.) and the excess water vapor it contains is condensed into pure liquid water. This pure liquid water is reintroduced into the reaction chamber C1of the reaction enclosure1.

6.2.3. End of Reaction

At the end of the reaction, and as illustrated inFIG.6c:the oxidizable material11has been consumed, andthe by-products12are found in the lower part of the settling chamber C2.

As the corrosion reaction consumes water molecules, the level of alkaline aqueous solution contained in the reaction enclosure1is lower at the end of the reaction than at the start of the reaction.

As a result, a gas pocket17—called “gaseous sky”—at high pressure containing approximately 30% of hydrogen produced during the reaction is present in the reaction chamber C1.

6.2.3.1. Recovery of Hydrogen Contained in the Gaseous Sky

In order to improve the yield of the reaction, the method can comprise a sub-step consisting of recovering the hydrogen contained in this gaseous sky.

A first solution for recovering the hydrogen contained in the gaseous sky17consists of injecting pure water into the reaction enclosure from the supply system3. For this purpose, the transfer pump36is activated and the outlet valve35bis switched to a passing state to allow the transfer of pure water at high pressure from the tank32to the settling chamber C2of the reaction enclosure1. This induces the movement of the gaseous sky towards the gas collection system4for the recovery of the hydrogen contained therein.

A second solution for recovering part of the hydrogen contained in the gaseous sky17consists of:switching the isolation valve48into a blocked state to replace the storage receptacle in which the produced hydrogen was stored with an empty storage receptacle, and ofswitching the isolation valve48into a passing state once the empty storage receptacle is connected.

This second solution allows to recover approximately 75% of the hydrogen contained in the gaseous sky17.

6.2.3.2. Restoration to Operating Condition

A sub-step of restoring the installation to operating condition can also be implemented.

This restoration sub-step comprisescooling and bringing the installation to atmospheric pressure,purging the installation to empty the alkaline aqueous solution contained in the reaction enclosure,rinsing the reaction by-products12,recovering reaction by-products12.

For cooling and bringing the installation to atmospheric pressure, the inlet valve35aof the supply system3is switched to a state allowing the circulation of pure water between the collection system4and the supply system3. Thus, from this switching of the inlet valve35a, all the condensed water vapor (forming pure water) by the heat exchanger is routed to the tank32. Moreover, the degassing valve37is opened gradually to allow the gases to escape through the tank32which is at atmospheric pressure. This allows to reduce the pressure inside the reaction enclosure on the one hand and the collection system on the other hand. After an initial loss of pressure, the reaction solution begins to boil, actively evaporating some water and lowering the temperature. The water vapors are condensed in the heat exchanger41of the collection system4and the condensate thus obtained is reintroduced into the tank32of the supply system3.

To purge the installation, the control unit activates the first circulation valve25ato switch it into a passing state in order to allow the passage of the alkaline aqueous solution from the reaction enclosure1to the tank22. The circulation of the alkaline aqueous solution between the chambers C1, C2and the tank22can be provided by gravity or obtained by motorized action (using a pump). The alkaline aqueous solution thus purged can be reused subsequently to carry out a new corrosion reaction. This allows to limit the amount of soda used for the generation of hydrogen.

For rinsing the by-products, pure water from the supply system3can be poured into the settling chamber C1. This allows to rid the by-products12of any soda deposits present on their surfaces. The rinsing water is recovered in the tank22of the feed system2. Here again, this rinsing allows to limit the amount of soda used for the generation of hydrogen (in addition to cleaning the reaction by-products).

The lower part of the settling chamber is then detached to evacuate the solid by-products of the reaction.

The installation described above allows to generate hydrogen by:maximizing the amount of oxidizable material consumed,minimizing the amounts of water and soda consumed.

This installation also allows the generation of hydrogen at high pressure (up to 350 bars).

The reader will have understood that numerous modifications can be made to the invention described above without materially departing from the new teachings and advantages described here.