WO2014091128A1 - Pyrotechnic process for providing very highly pure hydrogen and associated device - Google Patents

Abstract

The subject matter of the present invention is a pyrotechnic process for providing very highly pure hydrogen (G) and also a device (20) suitable for implementing said process. Said process comprises: - the combustion of at least one solid pyrotechnic charge which generates hydrogen-containing gas (2) for the production of a hot hydrogen-containing gas (Gl) under pressure, containing at least 70% by volume of hydrogen; - the cooling of at least one part of said hot hydrogen-containing gas (Gl) under pressure, which is produced, then the expansion of said at least one part of said cooled hydrogen-containing gas (G2); and - the purification of said at least one part of said cooled and expanded hydrogen-containing gas (G3) by passage through a zeolite adsorbent filter (11) so as to obtain, at the outlet of said filter (11), a hydrogen-containing gas (G) containing at least 99.99% by volume of hydrogen.

Description

 Pyrotechnic method for providing very high purity hydrogen and associated device

The present invention relates to a pyrotechnic process for providing hydrogen of very high purity. Said method is advantageously used to power fuel cells, portable or onboard. The present invention also relates to a device suitable for implementing said method.

 The invention is particularly applicable in the context of the hydrogen supply of low and medium power (1 to 100 watts) fuel cells, used in the aeronautical and military fields, such as those equipping the drones and those equipping the infantrymen . The electrical powers targeted in this context are about ten times greater than the powers consumed by portable electrical appliances, such as mobile phones. The scope of the invention can be extended to onboard fuel cells of higher power, a few tens of kilowatts, used, for example, for the supply of aeronautical emergency power generators.

 Fuel cells are alternative sources of electrical energy that provide a response to new energy and environmental requirements. Fuel cells have a potential energy density on board at least 4 times higher than that of lithium batteries. They do not release greenhouse gases.

 The production of hydrogen to fuel fuel cells is therefore a technical problem of topicality, object of many researches.

 Processes have already been described for the production of hydrogen by cracking hydrocarbons, thermolysis (thermal decomposition in the absence of oxidant) of hydrides and hydrolysis of hydrides.

Another developed route is based on the use of pyrotechnic solid materials generating hydrogen by combustion. It makes it possible to overcome the problem of permanent storage of fluid (liquid or gaseous). It is particularly interesting insofar as said materials have a high stability in storage conditions and great simplicity of use. Such pyrotechnic solid materials generating hydrogen have in particular been described in patent applications EP 1 249 427, EP 1 405 823, EP 1 405 824, EP 1 496 035 and EP 2 265 545. They are in the form of blocks. , pellets, discs or grains. Their composition generally contains a hydrogenated reducing component of inorganic hydride, borazane or polymeric type of aminoborane (polyaminoborane) and an inorganic oxidizing component. Their combustion generates, with a good yield (~ 11 to 13% theoretical mass, ie ~ 70 mole / kg), hydrogen. Their combustion temperature (~ 800 K), not excessive (see below), is high enough that the reaction is self-sustaining after ignition. The self-sustaining combustion of these materials is favored by the pressurization in the combustion chamber. Such materials produce hydrogenated gas with a high hydrogen content, containing at least 70% by volume of hydrogen.

The gases fueling a fuel cell must be free, or at least contain extremely low levels, of species, such as CO, NH ₃ , C and H ₂ S, which can poison the catalyst of said battery. These gases must also be at suitable temperatures (less than 473 K, ideally less than 350 K so far, to spare the cell membrane) and at low overpressures (ideally from a few millibars to 5 bars) compared to at ambient (atmospheric) pressure. Finally, the particle content of said gases must be low.

With reference to such specifications, the composition of pyrotechnic solid materials hydrogen generators is in principle optimized to generate the least possible such gaseous species poisons for (the catalyst) the battery (in any case, the gases hydrogenated products produced by these materials are always likely to contain, at low rates, poison species for the cell and it is appropriate to purify them to deliver to said cell a hydrogen of purity greater than 99.9% by volume, to guarantee its life) and to burn at a moderate temperature (it is always desirable to lower the temperature of the hydrogenated gases produced by the combustion of these materials to a temperature of about 800 K (see above), to deliver to the battery a hydrogen at a temperature lower than 473 K, ideally less than 350 K). Hydrogenated gases produced by the combustion of said materials are also conveniently filtered to trap the solid particles they carry (particles that have not been retained in the gangue resulting from combustion). The filters used for trapping said solid particles comprise, for example, an arrangement of one or more corrugated metal grids or an arrangement of metallic elements having pores (of a few millimeters to a few nanometers in diameter).

 The patent application FR 2 906 805 describes a method for providing non-pressurized hydrogen which is in the way specified above. Said method comprises the combustion, at high pressure, of at least one solid pyrotechnic charge in at least one combustion chamber, said combustion generating hydrogen and the flow rate of said hydrogen generated in at least one tank of larger volume. This document does not really address the technical problem of purification of generated hydrogen. Nor does it address the technical problem of managing the temperature of said generated hydrogen.

 Furthermore, those skilled in the art are familiar with gas filtration devices using zeolite adsorbents of type A (3A, 4A, 5A) or X or Y. For the definition of these types of zeolite, reference may be made to the chapter 22 of the "Handbook of Zeolite Science and Technology", published on July 31, 2003 by CRC Press and in Chapter 10 of the book: "Petroleum Refining: Processes of Separation", OPHRYS editions, 1998.

US Pat. No. 2,882,243 thus describes synthetic A-type zeolites suitable for gas filtration. The patent application FR 2 232 511 describes the use of type 5A zeolites for the purification of gases containing type C0 ₂ and N ₂ species. US patent application 2007/084979 mentions the purification through a molecular sieve membrane of a hydrogenated gas generated by hydrolysis of a hydride or by thermolysis of a hydride. The membrane in question may be made of a metal such as palladium, a polymer such as polypropylene or a ceramic, such as a zeolite. This document of the prior art does not provide any teaching on the management of the operating parameters of the membranes mentioned, especially in view of the temperature of the hydrogenated gas generated (the palladium membranes operating hot while zeolites operate at room temperature).

 The adsorbent filters in zeolite hydrogen separation are indeed effective, particularly effective, when the temperature of the gases to be filtered is close to the ambient temperature (typically between 293 K to 323 K) and that the pressure of the gases to be filtered n does not exceed a few bars (that said pressure is typically 1.5 to 5 bar). In view of this state of affairs, there was therefore a real prejudice to associate pyrotechnic generation of gas (hot gases, under pressure) and purification of said gases on zeolite adsorbent filters.

 It is the merit of the inventors to propose, against this prejudice, a method for providing high purity hydrogen, based on this association, which is particularly advantageous, in particular in that its implementation delivers said hydrogen from high purity directly at temperatures and pressure suitable for use in supplying a fuel cell and in that the device suitable for this implementation, neither complex nor of a large size, is perfectly suitable for portable or embedded systems .

 With reference to the general technical problem of the provision (on demand) of very high purity hydrogen, particularly suitable for supplying hydrogen to fuel cells, the Applicant proposes a high-performance solution. This solution is therefore based on the combustion of at least one solid pyrotechnic charge generating hydrogenated gas (hydrogenated gas containing a substantial level of hydrogen), then the filtration, through a zeolite adsorbent filter, of at least a part of the hydrogenated gas generated (generally hydrogenated gas generated). This solution is analyzed in terms of process and device.

 According to its first object, the present invention therefore relates to a pyrotechnic process for providing hydrogen of very high purity. Said method comprises:

the combustion of at least one solid pyrotechnic charge generating hydrogenated gas for the production of a hydrogen gas, hot, under pressure, containing at least 70% by volume of hydrogen; - cooling at least a portion of said hydrogen gas, hot, under pressure, then produces the expansion of said at least a portion of said hydrogenated gas cooled; and

 - Purifying said at least a portion of said hydrogenated gas cooled and expanded by passing through a zeolite adsorbent filter to obtain, at the outlet of said filter, a hydrogenated gas containing at least 99.99% by volume of hydrogen.

The combustion of the at least one pyrotechnic charge is triggered, per se known, by the user system as soon as the operational energy requirement appears. It generates, in a manner known per se, within the (each) combustion chamber containing the (a) pyrotechnic charge, hydrogenated gas, hot (~ 800 K, see above), at high pressure (the pressure of operation of the at least one combustion chamber is generally between 10 ⁶ Pa and 10 ⁷ Pa (between 10 and 100 bar)). Several pyrotechnic charges (identical or not, generally identical), each arranged in a combustion chamber, can be ignited simultaneously or sequentially according to the hydrogen demand. The pyrotechnic charge (s) used are suitable for generating a hydrogenated gas containing at least 70% by volume of hydrogen. This text gives further details on such loads. The hydrogenated gas generated is delivered, hot, under pressure (generally at a pressure of less than or equal to 10 bar, more generally at a pressure of a few bars), at the exit of the combustion chamber in which it has been generated, hot, at high pressure. The person skilled in the art knows how to adjust the area of the delivery orifice (or even the delivery ports, if the combustion chamber concerned has more than one) of the gas to regulate the pressure and the rate of delivery of said gas.

In the context of the implementation of the process of the invention, at least a portion of the pyrotechnically generated hydrogenated gas is purified by passage through a zeolite adsorbent filter. It should be understood that at least a portion of the hydrogenated gas delivered has passed through such a filter, irrespective of the exact arrangement of the combustion chamber (s) (in operation) present and filter (s) present ( s). Thus, it is possible in particular that a single combustion chamber delivers in a single filter or in several arranged filters in parallel, that n combustion chambers are connected to a single filter or that each of the n chambers is connected to a filter .... We also mentioned "a" filter but it is easy to understand that it can not be excluded from In the context of the invention, purification is carried out successively on at least two filters arranged in series. In any case, in the context of the process of the invention, at least a portion of the hydrogenated gas produced pyrotechnically is purified by passing through (at least) a zeolite adsorbent filter. For the sake of simplification of the description of the process of the invention, reference is hereinafter made to such a filter. It has been reported that at least a portion of the pyrotechnically generated hydrogen gas is thus purified. In general, the totality of the hydrogenated gas generated pyrotechnically is thus purified but it can not be excluded from the scope of the present invention that part of the pyrotechnically generated hydrogenated gas is not oriented for purification to the adsorbent filter in zeolite but used at a lower temperature. other purpose (for other purposes).

 The adsorbent filter in zeolite (natural or synthetic) used in the context of the implementation of the process of the invention (for purifying the hydrogenated gas produced, in an original manner, pyrotechnically) is of the type of those of the prior art, used to purify hydrogenated gases. It is advantageously a adsorbent filter synthetic zeolite type A, very advantageously type 5A.

With reference to the effectiveness of the adsorbent filters in zeolite for separating hydrogen (see above), it is understood that pyrotechnically generated hydrogenated gas according to the invention, ie hot and under pressure (see above), does not can be charged directly through such a filter. Thus, in the context of the process of the invention, part of the (or all) hydrogenated gas produced (pyrotechnically), hot, under pressure, is successively cooled and relaxed before purification. These cooling and expansion, implemented upstream of the purification (with reference to the operating conditions of the adsorbent filter in zeolite used for said purification), are also appropriate in that they ensure at the same time, the delivery, out of said filter, a gas suitable for supplying a hydrogen cell, ie a gas not only of very high purity (it contains at least 99.99% by volume of hydrogen) but also at a temperature close to the ambient temperature (typically between 293 K to 323 K) and at a pressure of at most 5.10 ⁵ Pa (5 bar).

 In the context of the implementation of the process of the invention, at least a portion (or all) of the hydrogenated gas produced pyrotechnically (hot, under pressure) is therefore successively:

 cooled, advantageously cooled to a temperature between 293 K and 323 K (being circulated in a coil-shaped heat exchanger, for example); then

- at a pressure of at most 5.10 ⁵ Pa (5 bar), generally between 1.5 × 10 ⁵ Pa and ⁵ × 10 ⁵ Pa (between 1.5 and 5 bar) (using, for example, a regulator and regulator of debit),

before coming into contact with the zeolite adsorbent filter (before being purified using the zeolite adsorbent filter).

 These two successive stages of cooling and expansion are generally carried out on all the hydrogenated gas produced pyrotechnically but, as indicated above, a portion of the hydrogenated gas generated pyrotechnically (not intended to be purified according to the invention ) is not excluded from the scope of the invention.

 According to an alternative embodiment of the process of the invention, the at least part of the hydrogenated gas produced, after having been cooled, is stored under pressure, in an intermediate manner, before being relaxed. It is thus stored before being expanded and then delivered, at a constant rate or on demand, to the adsorbent filter in zeolite. The intermediate storage of hydrogenated gas produced and cooled increases the amplitude of its cooling.

 According to another alternative embodiment of the process of the invention, which advantageously accumulates but not necessarily with the previous one (intermediate storage), the at least one portion of hydrogenated gas produced to be purified is filtered (to remove it at less in part of the solid combustion residues it contains) before coming into contact with the zeolite filter. Such filtration is implemented (conventionally (see the introduction to this text)) upstream of the trigger and also, advantageously, upstream of the cooling.

A particularly advantageous implementation of the method of the invention therefore comprises the following steps: the combustion of at least one pyrotechnic charge to produce hot hydrogenated gas under pressure (for a short time),

 the filtration of at least a portion of said hydrogenated gas,

 cooling said at least part of said filtered hydrogenated gas (in particular by circulating the gas in a heat exchanger),

 intermediate storage (under pressure) of said at least part of said cooled filtered hydrogenated gas,

 the expansion of said at least part of said filtered hydrogenated gas cooled and then stored, and

 the purification of the said at least part of the cooled filtered hydrogenated gas stored and expanded (ie the passage of the gas, continuously or on demand, in a zeolite adsorbent filter, while it is at a suitable temperature and pressure , suitable for carrying out such purification through said filter).

 These 6 successive steps are generally implemented with filtration, cooling, storage, expansion and purification of all the hydrogenated gas generated pyrotechnically.

 At the end of the filter, very high purity hydrogen

(Containing at least 99.99% by volume of hydrogen), under temperature conditions (close to ambient, see above) and pressure (at low pressure, see above) of interest, is issued. Such a hydrogen is ideal for fueling a fuel cell.

 It is now proposed to give details of the pyrotechnic charges suitable for the implementation of the method of the invention.

Said loadings may consist of loadings of the prior art, consisting of at least one product of conventional type, ie of the block, disc, pellet, grain type ... with a composition of: oxidizing component (s) type (s) ) Inorganic (s) + Hydrogenated Reducing Component (s) (see Introduction to this text). In any event, the at least one pyrotechnic charge used for the implementation of the method of the invention is selected to pyrotechnically generate a hydrogenated gas containing at least 70% by volume of hydrogen. It is indeed from such a hydrogenated gas that purification on membrane generates the hydrogen of very high purity desired.

Particularly suitable for the implementation of the method of the invention, the pyrotechnic charges consist of at least one pyrotechnic product containing, for at least 96% of its mass, at least one inorganic oxidizing component and at least one hydrogenated reducing component selected inorganic hydrides, borazane and polyaminoboranes. The at least one inorganic oxidizing component (generally only one inorganic oxidizing component is present but the presence of at least two in admixture can not be excluded) and the at least one specific hydrogenated reducing component (generally a single hydrogenated reducing component such as identified above is present but the presence of at least two in a mixture can not be excluded) therefore represent at least 96% by weight (or even at least 98% by weight, or even 100% by weight) of the mass of pyrotechnic product (s) advantageously used (s) to generate, according to the invention, the combustion gases. The optional 100% supplement is generally composed of additives, such as process auxiliaries, stability, desensitization with static electricity (such as Si0 ₂ ) and / or ballistic, combustion modifiers. The presence of impurities is not excluded.

 With reference to said at least one hydrogenated reducing component, it is possible, in no way limiting, to specify the following.

1) The at least one inorganic hydride that may be present in the composition of the pyrotechnic products used is advantageously a borohydride, very advantageously an alkaline or alkaline earth borohydride. Preferably, said at least one inorganic hydride is selected from sodium borohydride, lithium or magnesium. Pyrotechnic products used in the method of the invention therefore preferably contain in their composition, such as organic hydride, NaBH _4, LiBH ₄ or Mg (BH _{4) 2.}

2) The at least one hydrogenated reducing compound preferably however consists of borazane or a polymer of aminoborane (a polyaminoborane). Particularly preferably, borazane is the only hydrogenated reducing compound present in the composition of the pyrotechnic products used. With reference to said at least one inorganic oxidizing component, it is possible, in no way limiting, to specify the following.

 It is advantageously chosen from those used according to the prior art in the technical field of fuel cells; i.e. among:

 perchlorates (it very advantageously consists of ammonium perchlorate),

 dinitroamides ("dinitramides") (it very advantageously consists of ammonium dinitroamidure),

 nitrates (it very advantageously consists of strontium nitrate), and

- metal oxides (particularly preferably it consists of iron oxide (Fe ₂ O 3), vanadium oxide (V ₂ O _5), aluminum oxide (Al ₂ O _3), oxide titanium (TiO ₂ ), manganese oxide (MnO ₂ ), preferably iron oxide (Fe ₂ O ₃ )).

The pyrotechnic products (constituting the pyrotechnic charges) used in the process of the invention therefore very advantageously contain NH ₄ CIO ₄ , NH ₄ N (NO ₂ ) ₂ , Sr (NO ₃ ) 2 or Fe ₂ O ₃ .

 In the context of this variant, the pyrotechnic product (s) used preferably contains in its (their) composition:

 from 40 to 80% by weight of at least one hydrogenated reducing component as identified above (generally of such a hydrogenated reducing component), and

 from 20 to 60% by weight of at least one inorganic oxidant (generally of such an inorganic oxidant).

 They contain, particularly preferably:

from 55 to 75% by weight of at least one hydrogenated reducing component as identified above (generally of such a hydrogenated reducing component), and

 from 25 to 45% by weight of at least one inorganic oxidant

(usually such an inorganic oxidant).

It is generally also very advantageous for said pyrotechnic product (s) to contain (s) more than 50% by weight of hydrogenated reducing component (s). , even more advantageous that said (s) product (s) pyrotechnic (s) contains (s) more than 70% by weight of hydrogenated reducing component (s). We have understood that said hydrogenated reducing component (s) present constitute (s) the hydrogen reserve.

 It is recalled here, for all practical purposes, that the at least one pyrotechnic charge used for the generation of hydrogenated gases consists of at least one pyrotechnic product (generally several) in the form of grains, pellets, disks or blocks. These grains, pellets and blocks have any shape, for example spherical, ovoid or cylindrical. The grains usually have a mass of a few milligrams, pellets a mass of a few tenths of grams to a few grams, discs of a few tens of grams to a few hundred grams and blocks of a hundred grams to a few kilograms.

 The processes for obtaining these solid pyrotechnic products are known methods, described in particular in the EP patent applications identified on page 2 of this text.

 It is understood that said at least one pyrotechnic charge used generally contains several pyrotechnic products (although the use of a single product, such as a block, is not excluded).

In such a context, all the products constituting said at least one load do not necessarily have the same composition (or the same shape). However, they are all generators of hydrogenated gas within the meaning of the invention.

 Said at least one pyrotechnic charge burns upon ignition. The ignition device generally consists of an igniter, in connection with the user system, via a sealed passage supporting the operating pressure, and possibly at least one ignition relay charge.

Advantageously, when the user system allows it, the igniter is triggered by mechanical stress (for example by means of a piezoelectric relay or a primer striker), in order to avoid any unnecessary consumption of electrical energy for trigger the system.

Thus, the process of the invention is advantageously triggered by mechanical stress.

In view of the above remarks, it is understood that the process of the invention is particularly suitable for supply, hydrogen very high purity, low pressurized (a few millibars at 5 bar), and at a suitable temperature (less than 473 K, ideally less than 350 K, advantageously between 293 K and 323 K), of fuel cells, portable or on board. Hydrogen of very high purity, low pressure, at a temperature close to ambient, delivered out of the zeolite filter associated with at least one combustion chamber, is ideal for such use. The invention can actually be analyzed as a process for supplying very high purity hydrogen of a fuel cell; said method comprising the pyrotechnic process for providing very high purity hydrogen, as described above (including high pressure combustion and then filtering at least a portion (generally all) of the hydrogenated gases produced at through a zeolite adsorbent filter for the separation of gaseous hydrogen,) followed by the delivery of said hydrogen of very high purity to said fuel cell. It should be noted, however, that the very high purity hydrogen obtained on demand by the process of the invention can be used in other contexts.

 According to its second object, the present invention relates to a pyrotechnic device for providing (on demand) hydrogen of very high purity. Said device is suitable for implementing the method described above. It includes, typically:

 at least one combustion chamber provided with at least one delivery orifice that is suitable for the arrangement and the high-pressure combustion, within it, of a solid pyrotechnic charge generating hydrogenated gas, as well as for the delivery hydrogenated gas, hot, under pressure, via said at least one delivery port;

 gas cooling means arranged downstream of said at least one delivery orifice;

 gas expansion means arranged downstream of said cooling means;

 at least one zeolite adsorbent filter;

 means for delivering the purified gas, arranged at the outlet of said at least one zeolite adsorbent filter;

said combustion chamber (s), cooling means, expansion means and adsorbent filter (s) made of zeolite being placed in communication, so that hydrogenated gas delivered from said chamber (s) of combustion is directed, cooled and expanded to at least one zeolite adsorbent filter.

 The device of the invention is generally designed to direct all the generated gas to the at least one filter but, as indicated above, it can not be ruled out that it contains means arranged between the at least one filter and said at least one combustion chamber (more particularly at the outlet of the at least one combustion chamber) for deriving a portion of said generated gas.

 It has already been understood, in consideration of the foregoing, that many arrangements of combustion chamber (s) and filter (s) adsorbent (s) zeolite present are possible, it being understood that at least a portion of the gas delivered (or all of it) must be purified by passage through at least one zeolite adsorbent filter. Note that the use of a single zeolite adsorbent filter in combination with at least one combustion chamber is recommended.

With regard to said at least one combustion chamber, it is possible, in no way limiting, to indicate the following. Said at least one combustion chamber is per se known. It generally consists of a mechanical assembly containing an ignition device or initiation module (such a module advantageously triggers ignition by mechanical biasing, and such a module therefore advantageously comprises a piezoelectric relay or a primer striker ( see above)), a device for maintaining the main pyrotechnic charge (whose various constituent elements (the presence of a single block is however expressly provided for) may be loose or arranged, so as to limit the bulk ) and possibly a pyrotechnic pellet ignition relay. The loading (which can therefore be monoblock) is generally maintained in a basket, so that the combustion residues are retained in said basket (they constitute a gangue). When said loading consists of several elements, they are stabilized within said basket. This limits and the size and the mechanical stresses of said elements in response to the vibrations of the system. Said at least one combustion chamber comprises at least one delivery orifice for the delivery (under pressure) of the gases generated within it (at high pressure). Downstream of said at least one combustion chamber, there are means successively suitable for gas cooling (said means may notably consist of a coil-shaped heat exchanger) and gas expansion (said means may in particular consist of: minus a regulator and gas flow regulator (here pyrotechnic combustion gases)).

 Between said cooling and expansion means, there can be arranged a reservoir for temporarily storing the cooled gases.

 It has furthermore been seen that, according to an alternative embodiment of the method, the gases generated (at least a part of them) are filtered upstream of their expansion, and advantageously upstream also of their cooling. The device of the invention is therefore likely to further include filtration means suitable for implementing such a filtration. Such means may for example comprise, as indicated in the introduction to this text, an arrangement of one or more corrugated metal grids or an arrangement of metal elements having pores (a few millimeters to a few nanometers in diameter). The filtration means, able to rid the gas of at least a portion of the solid combustion residues they contain, when they are present, are therefore arranged upstream of the expansion means and also, advantageously, upstream of the means cooling (of course, downstream of the at least one combustion chamber).

 The at least one zeolite adsorbent filter is suitable for purifying hydrogenated gases, for separating hydrogen from said hydrogenated gases. It is advantageously a adsorbent filter synthetic zeolite type A, very advantageously type 5A.

 The means for delivering the purified gas generally comprise essentially a conventional pipe. They are advantageously suitable for delivering said gas to the user system. Said user system, as indicated above, advantageously consists of at least one fuel cell. Thus, the device of the invention is advantageously arranged upstream of at least one fuel cell.

The device of the invention (at least one device of the invention) is advantageously integrated in the structure of a system, in particular a portable or embedded system, for example an airborne system. It can thus be integrated into the structure of an airborne vehicle, for example the fuselage or wings of such a machine.

 It is now proposed to illustrate the invention, in no way limiting, by the appended figure (Figure 1) and the example below.

 Said single figure schematizes in section a device of the invention, according to a preferred embodiment, suitable for implementing the method of the invention, according to a preferred embodiment variant. Said example specifies such a preferred implementation variant.

 The device 20 of the invention, shown diagrammatically in FIG. 1, comprises six combustion chambers 1 each containing a pyrotechnic charge generating hydrogenated gas 2 and each provided with an initiation module 3 (of their charge 2 ) and a delivery port 4 hydrogenated gas (generated within them by combustion of their load 2). The delivery ports 4 open into the same pipe 5. Through said pipe 5, said delivery ports 4 are connected to a particle filter 6. A heat exchanger 7, in the form of a coil, is connected to said particle filter 6 and is adapted to convey, while cooling, the hydrogenated gas to an intermediate storage tank 8. Said tank 8 is provided with a regulator and flow regulator member 9, connected to a purification chamber 10 incorporating an adsorbent filter into zeolite 11. The purification chamber 10 is then connected to a fuel cell 13 via a pipe 12.

 One mode of operation of the device 20 of the invention, as shown diagrammatically in FIG. 1, is specified, by way of example, hereinafter.

One (several) of the six hydrogen-generating pyrotechnic charges 2 included in the combustion chambers 1 are (are) lit (simultaneously or sequentially) by means of its (their) initiation module 3. The combustion of des) said (s) load (s) 2 generates, in the (the) chamber (s) of combustion 1 which (s) contains (s), hydrogen gas G0, hot (at about 800 K), a high pressure (between 10 ⁶ and 10 ⁷ Pa (10 to 100 bar)). Said hot hydrogenated gas at high pressure G0 is delivered via the delivery orifice (s) 4. After delivery, it is conveyed under pressure (at a lower pressure (that the pressure indicated above, high operating pressure of the combustion chamber (s) in operation), at a pressure of generally a few bars to about 10 bars, in the tubing 5. The gas carried hot under pressure is referenced Gl in Figure 1. It is filtered in the solid particle filter 6, and then cooled in the exchanger 7 (coil-shaped pipe). It is cooled down to a temperature of less than 323 K. The cooled gas is referenced G2 in FIG. 1. Downstream of the heat exchanger 7, the cooled gas G2 is stored in the temporary tank 8. In said tank 8, the pressure of the gas is from a few bars to a dozen bars. The storage of the cooled gas in the tank also contributes to its cooling. From said tank 8, the gas is then discharged, continuously or on demand, through the expander and flow regulator 9. It is discharged at a flow rate of about 500 ml / min and at a pressure between 1.5 and 5 bars; this overpressure is appropriate with reference to the pressure drop caused by the crossing of the filter 11 (see below). The gas discharged (expanded) is referenced G3 in Figure 1. It is fed into the purification chamber 10 incorporating the adsorbent filter zeolite 11 (zeolite type 5A). Said adsorbent filter zeolite 11 retains, in large part, gaseous polluting species (present in very minor amount), such as NH ₃ (the content of NH 3, less than 1% by weight before purification is less than 0.01% by weight after purification). Hydrogen G is delivered downstream, at a purity greater than 99.99%, at a temperature of less than 323 K, and, taking into account the pressure losses of the gas while passing through the adsorbent filter in zeolite 11, at a lower pressure. at 5 bars at the fuel cell 13.

Claims

1. pyrotechnic method for providing hydrogen of very high purity (G), characterized in that it comprises:  the combustion of at least one solid pyrotechnic charge generating hydrogenated gas (2) for the production of a hydrogen gas (G1), hot, under pressure, containing at least 70% by volume of hydrogen;  the cooling of at least a portion of said hydrogenated gas (Gl), hot, under pressure, then produces the expansion of said at least a portion of said hydrogenated gas cooled (G2); and  - Purifying said at least a portion of said hydrogenated gas cooled and expanded (G3) by passing through a zeolite adsorbent filter (11) to obtain, at the exit of said filter (11), a hydrogenated gas (G) containing at least 99.99% by volume of hydrogen.  2. Method according to claim 1, characterized in that said at least a portion of said hot hydrogen gas, under pressure, produces (G1) is cooled to a temperature between 293 K and 323 K. 3. Method according to claim 1 or 2, characterized in that said at least a portion of said cooled hydrogenated gas (G2) is expanded at a pressure of at most 5.10 ⁵ Pa (5 bar).  4. Method according to any one of claims 1 to 3, characterized in that said at least a portion of said hydrogenated gas cooled (G2) is stored, intermediate, before being relaxed.  5. Method according to any one of claims 1 to 4, characterized in that it further comprises the filtration of the at least a portion of said hydrogenated gas produced to be purified to rid it at least partly of the residues solid of combustion that it contains; said filtration being carried out upstream of the expansion and also, advantageously, upstream of the cooling. 6. Process according to any one of claims 1 to 5, characterized in that it comprises, successively, the production of said hydrogenated gas (G1), the filtration of at least a portion of said hydrogenated gas (G1) to rid it at least in part of the solid combustion residues contained therein, cooling said at least one part of said hydrogenated gas (G1) filtered, the intermediate storage of said at least a portion of said hydrogenated gas filtered and cooled (G2), the expansion of said at least a portion of the hydrogenated gas filtered, cooled and stored and the purification of said at least a portion of said hydrogenated gas (G3) filtered, cooled, stored and relaxed.  7. Method according to any one of claims 1 to 6, characterized in that said at least one pyrotechnic solid hydrogenated gas generator (2) is a pyrotechnic charge consisting of at least one pyrotechnic product containing, for at least 96 % of its mass, at least one inorganic oxidizing component and at least one hydrogenated reducing component selected from inorganic hydrides, borazane and polyaminoboranes.  8. Process according to claim 7, characterized in that said at least one hydrogenated reducing component chosen from inorganic hydrides is chosen from inorganic borohydrides, advantageously alkali and alkaline earth borohydrides, very advantageously sodium borohydrides, lithium borohydrides and magnesium.  9. The method of claim 7, characterized in that said at least one hydrogenated reducing component is selected from borazane and polyaminoboranes; in that said at least one hydrogenated reducing component is advantageously borazane.  10. Process according to any one of claims 7 to 9, characterized in that said at least one inorganic oxidizing component is selected from perchlorates, dinitroamides, nitrates and metal oxides; advantageously among ammonium perchlorate, ammonium dinitroamide, strontium nitrate and iron oxide.  11. Method according to any one of claims 7 to 10, characterized in that said at least one pyrotechnic product contains:  from 40 to 80% by weight of said at least one hydrogenated reducing component (generally of such a hydrogenated reducing component), and from 20 to 60% by weight of said at least one inorganic oxidizing component (generally of such an inorganic oxidizing component); in that said at least one pyrotechnic product advantageously contains:  from 55 to 75% by weight of said at least one hydrogenated reducing component (generally of such a hydrogenated reducing component), and  from 25 to 45% by weight of said at least one inorganic oxidizing component (generally of such an inorganic oxidizing component).  12. Method according to any one of claims 7 to 11, characterized in that said at least one pyrotechnic product contains more than 50%, preferably more than 70% by weight of said at least one hydrogenated reducing component.  13. Method according to any one of claims 1 to 12, characterized in that it is implemented for feeding at least one fuel cell (13).  Pyrotechnic device (20) for providing very high purity hydrogen (G), suitable for implementing the method according to any one of claims 1 to 13, characterized in that it comprises:  at least one combustion chamber (1) provided with at least one delivery orifice (4) suitable for the arrangement and the high-pressure combustion, within it, of a solid pyrotechnic charge generating hydrogenated gas ( 2), and the delivery of hydrogen gas (G1), hot, under pressure, via said at least one delivery port (4);  gas cooling means (7) arranged downstream of said at least one delivery orifice (4);  gas expansion means (9) arranged downstream of said cooling means (7);  at least one zeolite adsorbent filter (11);  - Delivery means (12) of the purified gas arranged out of said at least one zeolite adsorbent filter (11); said combustion chamber (s) (1), cooling means (7), expansion means (9) and adsorbent filter (s) made of zeolite (11) are placed in communication, so that hydrogenated gas of (the) combustion chamber (1) is directed, cooled and expanded to at least one zeolite adsorbent filter (11).  15. Device (20) according to claim 14, characterized in that said cooling means (7) are of the heat exchanger type coil.  16. Device (20) according to claim 14 or 15, characterized in that said expansion means (9) consist of at least one expander and flow regulator.  17. Device (20) according to any one of claims 14 to 16, characterized in that it further comprises a reservoir (8) arranged between said cooling means (7) and said expansion means (9) .  18. Device (20) according to any one of claims 14 to 17, characterized in that it further comprises filtration means (6) of the gas (G1), able to rid it of at least one part of the solid combustion residues it contains, arranged upstream of the expansion means (9) and also, advantageously, upstream of the cooling means (7).  19. Device (20) according to any one of claims 14 to 18, characterized in that said zeolite filter is synthetic zeolite type A, preferably of type A.  20. Device (20) according to any one of claims 14 to 19, characterized in that it is arranged upstream of at least one fuel cell (13).