INSTALLATION FOR THE PRODUCTION OF HYDROGEN BY WATER VAPOR ELECTROLYSIS

Abstract

The invention relates in particular to a dihydrogen production installation, comprising an electrochemical device (1) and a fluid network which includes at least one inlet pipe (3) configured to convey an inlet fluid stream to the electrochemical device (1). The inlet pipe (3) is equipped with a first heat exchanger (10), belonging to a first heating stage (E1) of the inlet stream, which uses the heat from an outlet stream (4, 9) of said electrochemical device (1) to increase the heat of said inlet fluid stream through a recirculation branch, and with an electric gas heater (5), positioned downstream of said first heat exchanger (10). The inlet pipe (3) is also equipped with a second heat exchanger (20) belonging to a second heating stage (E2), the two heating stages (E1, E2) being positioned one after the other on said inlet pipe (3). Figure for the abstract: [Fig. 3]

Description

Title of the invention: INSTALLATION FOR THE PRODUCTION OF HYDROGEN BY WATER VAPOR ELECTROLYSIS technical field

[0001] The invention relates to the field of industrial production of hydrogen from water vapor through the use of high-temperature electrolysis technology

[0002] The invention relates to an installation for recovering heat to heat the water vapor and any air supplied to the electrolysis stacks in order to improve the energy efficiency of the electrolysis system. Prior art

[0003] In the field of dihydrogen production, it is known to carry out high-temperature electrolysis using an electrochemical device forming a reaction zone designed to convert water vapor into dihydrogen. In other words, the electrochemical device performs vapor-phase electrolysis with water vapor at a temperature that can be between 650°C and 850°C.

[0004] The reaction zone of a conventional electrolyzer is formed by stacks of cells, each having an anode, a cathode, and an electrolyte. High-temperature electrolysis decomposes water vapor to form, at the cell cathode, a flow of fluid comprising dihydrogen and unreacted water.

[0005] To enable this reaction, water vapor is introduced into an electrolyzer maintained at a temperature between 650°C and 850°C.

[0006] This solution requires an external energy input, in particular to obtain the water vapor at the desired temperature at the inlet of the electrolyzer.

[0007] Various systems are known that include heat exchangers and electric gas heaters installed on the steam (more commonly called fuel) inlet line and on the air inlet line. The gas heaters and exchangers allow, in particular, for increasing the temperature of the fuel (or the air in the air line) in order to reach the desired temperature at the inlet of the electrolyzer. These systems are also called "Hot Balance of Plant" or "Hot BoP" in English.

[0008] Typically, these systems comprise a first part of the installation with a fuel inlet (steam stream with a fraction of hydrogen) at a temperature of approximately 150 °C, and a second part of the installation with an air inlet at a lower temperature (approximately 90 °C): a heat exchanger positioned The fuel inlet pipe uses a hot stream, resulting from the reaction occurring in the electrolyzer, to heat the fuel stream entering the first part of the installation. However, the fuel stream temperature thus achieved is insufficient; therefore, downstream of the heat exchanger, on the pipe, a gas heater (powered by electricity) is installed to allow the fuel stream to reach the desired temperature.

[0009] The object of the present invention is to minimize the action of the gas heater, downstream of the exchanger, in order to save energy and make the installation more efficient.

[0010] Indeed, known Hot BoP systems have certain drawbacks. In particular, due to the mass transport from the fuel circuit to the air circuit through the stacks during hydrogen production, there is an imbalance in the mass flow rate between the fuel and air sides: - The return fuel stream contains hydrogen, while the incoming fuel stream is primarily composed of steam. This imbalance makes heating the steam through heat recovery less efficient, and - The opposite occurs on the air side with a return flow of O2-enriched air with a higher flow rate than the incoming air flow, making the return flow more difficult to cool.

[0011] Moreover, on the fuel side, the cold stream used to cool the hydrogen produced is steam heated to approximately 150 degrees C. It is therefore difficult to cool the hydrogen stream below 200 °C - 250 °C, which requires increased cooling power from the aerodynamic cooling systems and downstream cooling systems.

[0012] Finally, reducing the treatment airflow rate is beneficial for the overall efficiency of the system, as it avoids heating air that does not have an electrochemical function.

[0013] However, reducing the air supply further unbalances the mass flow rates on the air side between the supplied air and the returned O2-enriched air. The output flow of O2-enriched air then becomes warmer, which represents a waste of heat and may even require downstream cooling, thus increasing the energy consumption of the aerosol cooling system.

[0014] The invention aims to provide a system that delivers better performance by solving the problems stated above. Description of the invention

[0015] To achieve this objective, the invention proposes a dihydrogen production installation, comprising an electrochemical device and a fluidic network which includes at least one inlet line configured to convey to the electrochemical device an inlet flow of fluid such as a fuel flow, so as to produce dihydrogen by means of said electrochemical device, said electrochemical device comprising an anode, a cathode and an electrolyte, said inlet line of the fluidic network being equipped: - of a heat exchanger, using the heat from an outgoing flow of said electrochemical device to increase the heat of said incoming fluid flow through a recirculation branch of said outgoing flow, and - of an electric gas heater, positioned between said heat exchanger and the inlet of said electrochemical device (1).

[0016] The installation according to the invention is remarkable in that said heat exchanger is a first heat exchanger belonging to a first stage of heating the inlet flow, and in that said inlet pipe is equipped with a second heat exchanger belonging to a second stage of heating the inlet flow, said first and second stages of heating the inlet flow being positioned one after the other on said inlet pipe, between the inlet of said pipe and said electric gas heater.

[0017] Thanks to the presence of two heating stages, each comprising at least one heat exchanger, the installation is more efficient: the two heating stages can, in fact, allow the heat from a second circuit to be recovered, as will be seen in the embodiments which will be described later, so that the same installation remains efficient in all circumstances, whether the electrochemical device it includes is implemented or not.

[0018] The installation according to the invention may also include the following features, taken separately or in combination:

[0019] According to an advantageous embodiment, said outgoing flow from said outgoing flow recirculation branch is a fuel flow evacuated from said cathode of said electrochemical device.

[0020] According to a first embodiment of the installation according to the invention, it comprises a second recirculation branch of a second outgoing flow of said electrochemical device and a third heat exchanger in which circulates said second outgoing flow of the second recirculation branch, said third heat exchanger participating in the heating of the inlet flow of the inlet pipe, said third heat exchanger belonging to said first stage of heating the inlet flow.

[0021] Advantageously, according to this embodiment, the installation includes an inlet flow separator positioned on said inlet pipe, between the inlet of said inlet pipe and said first heating stage, to pass a first part of the inlet flow and a second part of the inlet flow through, respectively, said first and third heat exchangers of said first heating stage, the first and second parts of the flow being gathered upstream of said second heating stage to pass the whole of the gathered flow into the second heat exchanger of said second heating stage.

[0022] Preferably, said inlet fluid flow of said inlet pipe includes a water vapor flow, the inlet pipe includes, between said inlet flow separator and said first heat exchanger of said first heating stage, a dihydrogen inlet to enrich said first part of inlet flow passing through said first heat exchanger of said first heating stage with dihydrogen.

[0023] Preferably, the second outgoing flow from said second recirculation branch is a flow evacuated from said anode of said electrochemical device during the implementation of said electrochemical device.

[0024] In the context of a first particular embodiment, the second outgoing flux is dioxygen.

[0025] In a second embodiment of the installation, the inlet pipe of a fluid flow is a first inlet pipe (3), said network comprising a second inlet pipe of a second fluid flow, the second inlet pipe being equipped with a fourth heat exchanger included in said first heating stage and a fifth heat exchanger included in said second heating stage.

[0026] According to this second embodiment, said second fluid flow of said second conduit is an air flow supplying said anode of the electrochemical device.

[0027] Preferably, the second flow conduit includes an electric gas heater positioned between the second heating stage and said electrochemical device.

[0028] Preferably, the installation includes a second recirculation branch of a second outgoing flow from said electrochemical device, said second outgoing flow passing through said fifth heat exchanger in said first heating stage and said fourth heat exchanger included in said first heating stage, the second fluid recirculation branch being an air flow evacuated from the anode of the electrochemical device.

[0029] Furthermore, said fluid inlet flow of said first pipe includes a water vapor flow, the first pipe includes an inlet flow separator positioned on said first pipe, between the inlet of said first inlet pipe and said first heating stage, to allow a first part to pass of inlet flow and a second part of inlet flow through, respectively, said first and third heat exchangers of said first heating stage, the first and second parts of flow being gathered upstream of said second heating stage to pass the whole of the gathered flow into the second heat exchanger of said second heating stage.

[0030] Advantageously, the first inlet pipe includes, between said inlet flow separator and said first heat exchanger of said first heating stage, a dihydrogen inlet to enrich said first part of inlet flow passing through said first heat exchanger of said first heating stage with dihydrogen.

[0031] According to a third embodiment which will be presented later, said outgoing flow recirculation branch, passing through said first heat exchanger of the first heating stage, is an air flow evacuated from said anode of said electrochemical device, the installation comprising a second recirculation branch of a second outgoing flow from said cathode of said electrochemical device, said second flow passing through said second heat exchanger in said second heating stage and said fourth heat exchanger included in said first heating stage, the second flow of the second recirculation branch being a fuel flow.

[0032] According to this embodiment and advantageously, said inlet fluid flow of said first conduit includes a water vapor flow, said first conduit comprising, between said first heat exchanger of said first heating stage and the second heat exchanger of said second heating stage, a dihydrogen inlet to enrich said water vapor flow of the first conduit downstream of said first heat exchanger with dihydrogen.

[0033] In the case of an installation according to the invention comprising two heating stages, each with two heat recovery units, the installation could also be defined as follows:

[0034] According to an advantageous embodiment, the installation comprises an electrochemical device, including an anode, a cathode and an electrolyte, and a fluidic network comprising: - a first inlet conduit configured to convey, towards the cathode of said electrochemical device, a first inlet flow of fluid such as a fuel flow, so as to produce dihydrogen by means of said electrochemical device, - a second inlet duct configured to convey a second inlet flow of air to the anode of said electrochemical device, The first and second pipes are each equipped with an electric gas heater, - a first fuel flow recirculation branch, and - a second air recirculation branch, said first and second recirculation branches originating from said electrochemical device. The installation comprises two stages for heating the fuel and air streams from the first and second inlet pipes, each stage including a heat exchanger on each of the first and second inlet pipes fed by one or the other of the first and second fuel or air stream recirculation branches. In other words, each heating stage includes at least two heat exchangers.

[0035] Advantageously, the first stage includes three heat exchangers.

[0036] According to a particular embodiment, the heat exchangers of the first and second heating stage positioned on the first line are supplied by the first fuel flow recirculation branch, and the heat exchangers of the first and second heating stage positioned on the second line are supplied by the second air flow recirculation branch.

[0037] Preferably, in this embodiment, the fuel flow is a water vapor flow.

[0038] Preferably, in this embodiment, the first pipe includes a flow diverter positioned upstream of the first heating stage, dividing the fuel flow into two half-flows, the first half-flow of fuel passing through the heat exchanger of the first heating stage being enriched in dihydrogen and the second half-flow being diverted to a third heat exchanger of the first heating stage, the two half-flows being recombined at the outlet of the first heating stage.

[0039] In this embodiment, if the first heating stage comprises three heat exchangers, a first heat exchanger being positioned on the fuel flow inlet line, a second heat exchanger being positioned on the air flow inlet line and a third heat exchanger in which it is advantageous to circulate at least a part of the air flow from the second recirculation branch.

[0040] According to an alternative embodiment of the installation, - The heat exchanger for the first heating stage, positioned on the first fuel inlet line, is supplied by the second airflow recirculation branch, - The heat exchanger for the second heating stage, positioned on the first fuel inlet line, is supplied by the first fuel flow recirculation branch, - the heat exchanger of the first heating stage, positioned on the second air intake duct, is supplied by the first fuel recirculation branch, and - the heat exchanger of the second heating stage positioned on the second pipe is supplied by the second air flow recirculation branch.

[0041] Advantageously, the fuel for the flow in the first conduit is water vapor and the fluidic network includes a dihydrogen inlet positioned between the first and second heating stage.

[0042] Brief description of the figures

[0043] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0044] [Fig-1]: [Fig.1] is a schematic representation of a first mode of implementation of an installation conforming to the invention,

[0045] [Fig.2]: [Fig.2] illustrates a variant embodiment of the installation shown in [Fig.l],

[0046] [Fig.3]: [Fig.3] is a schematic representation of a second mode of implementation of an installation conforming to the invention,

[0047] [Fig.4]: [Fig.4] illustrates a variant embodiment of the installation shown in [Fig.3],

[0048] [Fig. 5]: [Fig. 5] is a schematic representation of a third mode of construction of an installation conforming to the invention, and

[0049] [Fig.6]: illustrates a variant embodiment of the installation shown in [Fig.5].

[0050] It is understood that the embodiments described below are in no way limiting. In particular, variants of the invention may be conceived comprising only a selection of the features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, or with only a portion of the structural details if this portion alone is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0051] In the figures and in the rest of the description, elements common to several figures retain the same reference. Detailed description

[0052] The objective of the invention is to optimize the heat recovery of hot gas flows exiting the chimneys of an electrochemical device to heat the fuel (and air) flow(s) entering the electrochemical device, in order to limit the electrical consumption of an electric gas heater which is currently implemented in the inlet pipes of the fuel (and air) flow(s) which feed the electrochemical device.

[0053] Three configurations are shown in figures 1 to 6.

[0054] None of these schemes includes a liquid water cooling circuit to lower the temperature of the hydrogen produced by the electrochemical device, but such circuits can be implemented downstream of the electrochemical device to improve the efficiency of the system.

[0055] The installation according to the invention focuses on the means of limiting the electrical consumption of the electric gas heaters positioned upstream of the electrochemical device.

[0056] Fig. 1 shows an installation according to the invention implemented in a SOE (Solid Oxide Electrolysis) system operating without processing air.

[0057] The installation includes an electrochemical device 1 and a fluidic network 2 which includes at least one inlet pipe 3 configured to convey to the electrochemical device 1 an inlet flow of fluid such as a fuel flow, so as to produce dihydrogen by means of said electrochemical device 1, said electrochemical device 1 comprising an anode 101, a cathode 102 and an electrolyte 103.

[0058] On the inlet pipe 3, we observe a first heat exchanger 10 and a second heat exchanger 20, each using the heat from an outgoing flow 4 of said electrochemical device 1.

[0059] The outgoing flow 4 is the fuel flow discharged through a pipe which is connected to the cathode 102 of the electrochemical device 1. The pipe carrying the outgoing flow 4 of fuel discharged through the first and second heat exchangers 10 and 20 constitutes a recirculation branch of said outgoing flow which makes it possible to increase the heat of the incoming flow in the pipe 3.

[0060] An electric gas heater 5 is also observed, positioned between the second heat exchanger 20 and the electrochemical device 1.

[0061] Thus implemented, the fuel flow inlet 3 comprises three levels of fuel flow temperature increase: a first level of heat increase ensured by the first heat exchanger 10, a second level of heat increase ensured by the second heat exchanger 20 and a final level of heat increase, ensured by the electric gas heater 5 which ensures that the temperature of the fuel fluid flow is at the correct temperature before being injected into the electrochemical device 1.

[0062] The fuel fluid flow temperature at the inlet of the installation in line 3 is approximately 150 °C. The set of elements ensuring the temperature increase of the fluid flow in line 3 brings the temperature of the fuel fluid flow to approximately 700 °C, or between approximately 600 and 850 °C, at the inlet of the electrochemical device 1.

[0063] The installation thus comprises two stages for heating the fuel fluid flow upstream of the electric gas heater: a first stage El comprising the first heat exchanger 10 and a second stage E2 comprising the second heat exchanger 20, the two heating stages El and E2 being positioned one after the other, both in said recirculation branch of said outgoing flow 4 and on said inlet pipe 3, between the inlet of said pipe and said electric gas heater 5.

[0064] On [Fig. 1], it is also observed that the installation includes a second recirculation branch 6, comprising a second evacuation pipe for a second flow and schematically represented on [Fig. 1] exiting from the anode of the electrochemical device 1.

[0065] This second recirculation branch 6 allows the evacuation of dioxygen which is produced during the implementation of the electrochemical device 1.

[0066] The second recirculation branch supplies a third heat exchanger 30, belonging to the first heating stage El in parallel with the first heat exchanger 1.

[0067] The third heat exchanger 30 also participates in heating the inlet flow in the inlet pipe 3: for this purpose, an inlet flow separator 7 is provided, positioned on said inlet pipe 3, between the inlet of said pipe 3 and said first heating stage EL

[0068] The input stream separator 7 allows the input stream to be separated into: - a first part of the flow that passes through the first heat exchanger 10 of the first heating stage El, and - a second part of the inlet flow which passes through the third heat exchanger 30 of the first heating stage EL

[0069] The first and second parts of the flow are gathered upstream of said second heating stage E2, to pass the entire gathered flow into the second heat exchanger 20 of the second heating stage E2.

[0070] In this way, the dioxygen evacuated from the electrochemical device 1 also contributes to increasing the heat of the inlet flow in the first heating stage El.

[0071] Thus, the temperature reached by the inlet flow at the outlet of the first heating stage is better than without the presence of the third heat exchanger 30 and saves energy to reach the ideal inlet temperature of the flow at the inlet of the electrochemical device 1.

[0072] It will be noted, in the figures, that the energy consumed by the electric gas heater 5 is symbolized by the arrow F when the electrochemical device is operating.

[0073] When the electrochemical device 1 is in operation ([Fig.1]), the two heat exchangers 10 and 30 of the first heating stage E1 recover up to 75% of the heat from the recirculation flows to be transferred to the fuel fluid flow in the inlet line, while the second heat exchanger 20 of the second heating stage E2 recovers about 25% of the heat from the recirculation flows.

[0074] If the electrochemical device is not operating, no oxygen is discharged through the second recirculation branch duct 6, and the third heat exchanger 30 has little or no effect on heating the inlet flow. In this case, the first heating stage E1 recovers approximately 40% of the heat from the recirculation flow of the first recirculation branch 4, while the second heating stage E2 recovers approximately 60% of the heat from this same recirculation flow of the first branch 4.

[0075] This first embodiment of an installation according to the invention thus shows that it guarantees the recovery of heat from a flow evacuated from the electrochemical device 1 to increase the temperature of the inlet flow of fuel fluid, whether this electrochemical device 1 is in operating mode or not.

[0076] The installation of [Fig.2] is the same as that shown in [Fig.1]. However, it is provided that the fuel flow circulating in the inlet pipe 3 is a water vapor flow S.

[0077] To promote the reaction in the electrochemical device 1, it is known to inject dihydrogen H2 into the water vapor stream.

[0078] To ensure that the injected dihydrogen H2 does not mix with a gas containing dioxygen, especially in its majority (which could cause a local flame in the event of an internal leak in the third heat exchanger 30), the dihydrogen injection inlet is provided only after the inlet flow separator 7, in the first part of the inlet fuel flow that passes through the first heat exchanger 10: in this way, the dihydrogen-enriched water vapor does not pass through the third heat exchanger 30 (through which the flow of the oxygen-rich recirculation branch passes) and the risks of damage to heat exchanger 30 are thus eliminated.

[0079] Reference will now be made to the embodiments shown in Figures 3 to 6:

[0080] Contrary to the embodiment of the installation shown in Figures 1 and 2, the embodiments of the installation shown in Figures 4 to 6 concern installations where a flow of treatment air is injected into the electrochemical device.

[0081] The embodiment shown in figures 3 and 4 is optimized for an electrolysis operation with a reduced air flow rate: for example, the installation provides an air flow rate corresponding to 30% of the fuel flow rate injected into the electrochemical device 1.

[0082] The embodiment shown in figures 5 and 6 is, for its part, optimized for an installation in which the air flow rate entering the electrochemical device is substantially the same as the fuel flow rate.

[0083] The installation shown in Figures 3 and 4 comprises two fluid inlet conduits, of which: - a first fuel flow inlet 3 (as in all the examples presented), and - a second inlet pipe 8 of a second fluid flow, the second fluid flow being air.

[0084] As with the installation according to the first embodiment described above, the inlet pipe 3 passes through two heating stages E1 and E2 of the circulating fuel flow, with a first heating stage E1 comprising a first 10 and a third heat exchanger 30, each through which a portion of the inlet fuel flow passes, after the latter has been divided into a first flow portion and a second flow portion by means of a separator 7 positioned between the inlet of the pipe 3 and the first heating stage E1

[0085] As with the installation according to the first embodiment presented above, the fuel flow inlet 3 passes through a second heating stage E2 comprising a second heat exchanger 20, as well as an electric gas heater 5, all of these means making it possible to bring the fuel flow to a desired temperature at the inlet of the electrochemical device 1.

[0086] As with the installation according to the first embodiment presented above, it includes a first fuel flow recirculation branch 4, which circulates the fuel flow exiting the electrochemical device through the first and second heat exchangers (10 and 20 respectively)

[0087] As illustrated in figures 4 and 5, said second air inlet duct 8 also passes through the two heating stages El and E2, and more particularly a fourth heat exchanger 40 included in the first heating stage El and a fifth heat exchanger 50 included in the second heating stage E2.

[0088] A second electric gas heater 5 is positioned on the second air inlet pipe 8, between the second heating stage E2 and the anode 101 of the electrochemical device 1.

[0089] The installation also includes a second recirculation branch 9 of a second outgoing flow from said electrochemical device 1.

[0090] The second recirculation branch 9 comprising a second evacuation conduit for the second flow: it is schematically represented on [Fig.3] or 4 exiting the anode of the electrochemical device 1.

[0091] The second flow is an air flow evacuated from the electrochemical device.

[0092] The second recirculation branch 9 of airflow passes through said fifth heat exchanger 50 in said second heating stage E2.

[0093] The second airflow circulation branch also passes through said third 30 and said fourth heat exchanger 40 included in said first heating stage EL. To this end, the second airflow recirculation branch includes a second airflow separator 7' positioned upstream of the third and fourth heat exchangers 30 and 40, preferably in said first heating stage EL.

[0094] Thus the third heat exchanger 30 is supplied with heat by the recirculating airflow from the second recirculation branch 9 to heat the second part of the fuel flow entering the inlet pipe 3.

[0095] This is also how the fourth heat exchanger 40 heats the second airflow inlet duct 8 with the heat from the recirculating airflow of the second recirculation branch 9.

[0096] The installation of [Fig.4] is the same as that shown in [Fig.3]. However, it is provided that the fuel flow 3, circulating in the inlet pipe 3, is a water vapor flow S.

[0097] For the same reasons as those set out in the presentation of the first embodiment (figures 1 and 2), to promote the reaction in the electrochemical device 1, it is known to inject dihydrogen H2 into the water vapor stream S.

[0098] To ensure that the injected dihydrogen H2 does not mix with a gas containing dioxygen, especially in large quantities (which could cause a local flame in the event of an internal leak in the third heat exchanger 30), the dihydrogen injection inlet point is provided only after the inlet flow separator 7, in the first part of the inlet fuel flow 3 which passes through the first heat exchanger 10: in this way, the water vapor enriched in dihydrogen does not pass through the third heat exchanger 30 (passed through by the flow from the recirculation branch rich in dioxygen) and the risks of damage to the heat exchanger 30 are thus eliminated.

[0099] In standby mode (i.e., when the electrochemical device is not in operation), the inlet flow line 3 is supplied with a protective gas containing approximately 4% hydrogen in 96% nitrogen. This protective gas is recirculated after passing through the stacks of the electrochemical device 1. In this "standby" operating mode, the heat exchanger 30 will not see hydrogen in the fuel (due to its low concentration of 4%), and oxygen will be present on the air side. However, there is no risk of combustion in "standby" mode since most of the heat recovery is ensured by the second heating stage E2, the gas temperature at the heat exchanger 30 being well below the auto-ignition temperature. Therefore, in the event of a leak in the heat exchanger 30, there is no major risk of combustion and subsequent internal damage.

[0100] In this embodiment shown in Figures 3 and 4, the first heating stage El, which includes the heat exchangers 10, 30 and 40, is designed to optimize heat recovery when the electrochemical device is in operation (when the chimneys are polarized).

[0101] The second heating stage E2, which includes heat exchangers 20 and 50, is intended to be the main heat recovery stage when the electrochemical device is in "standby" operating mode, without electrochemistry.

[0102] In this embodiment, when the electrochemical device is in "standby" operating mode, the majority of the heat exchange carried out by the second heating stage E2 represents approximately 75% of the total heat recovered.

[0103] Conversely, when the electrochemical device is in operating mode, most of the heat exchange takes place in the first heating stage El with its three heat exchangers 10, 30 and 40.

[0104] Thus, whether the electrochemical device is in operating mode or not, the embodiment of figures 3 and 4 works effectively.

[0105] The percentage values ​​of heat recovered by each heating stage are indicative and depend on actual operating conditions such as current density, steam conversion rate, steam flow rate, etc.

[0106] The last embodiment illustrated in Figures 5 and 6 comprises: - two heating stages E1 and E2, - two inlet and fluid flow circulation pipes, intended to supply the electrochemical device 1: a first fuel flow inlet pipe 3 and a second air inlet pipe 8.

[0107] The first warming stage El comprises: - a heat exchanger 10 positioned on the first fuel flow inlet pipe 3, and - a heat exchanger 40 positioned on the second air inlet pipe 8.

[0108] The second heating stage E2 comprises: - a heat exchanger 20 positioned on the first fuel flow inlet 3, downstream of the first heating stage El, and - a heat exchanger 50 positioned on the second airflow inlet 8, downstream of the first heating stage EL

[0109] It also includes a first fluid recirculation branch 4, ensuring the recirculation of fuel flow after passing through the electrochemical device 1, and a second air recirculation branch 9.

[0110] In this embodiment, the fuel recirculation branches 4 and air 9 each supply heat to a heat exchanger positioned on a fuel inlet 3 and air inlet 8.

[0111] More specifically, the first fuel flow recirculation branch 4 traverses the second heat exchanger 20 of the second heating stage E2, which heats the fuel stream from the first inlet duct 3, and the fourth heat exchanger 40 of the first heating stage El, which heats the air stream from the second air inlet duct 8.

[0112] The second airflow recirculation branch 9 passes through the fifth heat exchanger 50 of the second heating stage E2, which heats the airflow from the second inlet duct 8, and the first heat exchanger 10 of the first heating stage El, which heats the fuelflow from the first fuelflow duct 3.

[0113] Thus, this embodiment uses each fluid recirculation branch to supply heat into each of the air and fuel flow inlet lines.

[0114] As with the examples previously described, the fuel flow from the inlet line may include a water vapor flow S (see [Fig.6]).

[0115] In this case, it is also provided that the installation is equipped with a dihydrogen H2 inlet to enrich said water vapor stream of the first pipe with dihydrogen.

[0116] As can be seen in [Fig.6], the dihydrogen inlet is provided downstream of said first heating stage El, at the inlet of the second heat exchanger 20 of the second heating stage E2, the second heat exchanger 20 being positioned on the fuel flow inlet line and the recirculation branch passing through it being the first branch whose fluid is also fuel: thus, in the event of a leak in the lines passing through the second heat exchanger (fuel line and fuel recirculation branch), there is no risk of contact between dihydrogen and dioxygen.

[0117] This embodiment, shown in Figures 5 and 6, operates differently depending on whether the electrochemical device is in operating mode or in standby mode (see explanations of the "standby" operating mode above): in operating mode, the first heating stage E1 performs approximately 60% of the heat recovery, taking advantage of the heat exchange between the circuits to compensate for the mass flow imbalance in each circuit, which is a consequence of the electrochemical reaction in the electrochemical device 1. In "standby" mode, there is no mass flow imbalance in each circuit between the inlet and outlet flows. The second heating stage then performs most of the heat recovery: approximately 80% of the total heat recovered.

[0118] It is clear from the preceding description how the heating stages allow for the recovery of a maximum amount of heat from the recirculation flows, whether the electrochemical device is in operating or standby mode. This optimized heat recovery makes it possible to limit the use of electric gas heaters 5 on each of the ducts, thereby reducing the overall energy consumption of the installation and making it more efficient.

[0119] It should be understood that the invention could include variants of the embodiment of the installation not described, the three examples being given by way of illustration of the implementation of an installation according to the invention in different cases.

Claims

Demands

1. Hydrogen production installation, comprising an electrochemical device (1) and a fluidic network (2) which includes at least one inlet pipe (3) configured to convey to the electrochemical device (1) an inlet fluid stream such as a fuel stream, so as to produce hydrogen by means of said electrochemical device (1), said electrochemical device (1) comprising an anode (101), a cathode (102) and an electrolyte (103), said inlet pipe (3) of the fluidic network being equipped with: - a heat exchanger (10), using the heat from an outlet stream (4, 9) of said electrochemical device (1) to increase the heat of said inlet fluid stream through a recirculation branch of said outlet stream (4, 9), and - an electric gas heater (5), positioned between said heat exchanger (10) and the inlet of said electrochemical device (1),characterized in that said heat exchanger (10) is a first heat exchanger belonging to a first heating stage (E1) of the inlet flow, and in that said inlet pipe (3) is equipped with a second heat exchanger (20) belonging to a second heating stage (E2) of the inlet flow, said first and second heating stages (E1, E2) of the inlet flow being positioned one after the other on said inlet pipe (3), between the inlet of said pipe (3) and said electric gas heater (5).

2. Installation according to claim 1, characterized in that said outflow from said outflow recirculation branch (4) is a fuel flow discharged from said cathode (102) of said electrochemical device (1).

3. Installation according to claim 1 or 2, characterized in that it comprises a second recirculation branch of a second outgoing flow (6, 9) of said electrochemical device (1) and a third heat exchanger (30) in which said second outgoing flow of the second recirculation branch circulates, said third heat exchanger (30) participating in the heating of the inlet flow of the inlet pipe (3), said third heat exchanger (30) belonging to said first heating stage (El) of the inlet flow.

4. Installation according to claim 3, characterized in that it comprises an inlet flow separator (7) positioned on said inlet pipe (3), between the inlet of said inlet pipe (3) and said first heating stage (El), to pass a first part of the inlet flow and a second part of the inlet flow through, respectively, said first (10) and third (30) heat exchangers of said first heating stage (El), the first and second parts of the flow being gathered upstream of said second heating stage (E2) to pass the whole of the gathered flow into the second heat exchanger (20) of said second heating stage (E2).

5. Installation according to claim 4, characterized in that said inlet fluid flow of said inlet pipe (3) comprises a water vapor flow (S), in that said inlet pipe (3) comprises, between said inlet flow separator (7) and said first heat exchanger (10) of said first heating stage (El), a dihydrogen inlet for enriching said first part of inlet flow passing through said first heat exchanger (10) of said first heating stage (El) with dihydrogen.

6. Installation according to claim 3 or 4, characterized in that said second flow (6, 9) exiting said second recirculation branch is a flow evacuated from said anode (101) of said electrochemical device (1) during the implementation of said electrochemical device.

7. Installation according to claim 6, characterized in that said second outgoing flux (6) is dioxygen.

8. An installation according to any one of claims 1 or 2, characterized in that said inlet pipe (3) of an inlet fluid flow of said fluidic network (2) is a first inlet pipe (3), in that said network comprises a second inlet pipe (8) of a second fluid flow, in that said second inlet pipe (8) is equipped with a fourth heat exchanger (40) included in said first heating stage (E1) and a fifth heat exchanger (50) included in said second heating stage (E2).

9. Installation according to claim 8, characterized in that said second fluid flow of said second conduit (8) is an air flow supplying said anode (101) of the electrochemical device (1).

10. Installation according to claim 8 or 9, characterized in that said second flow conduit (8) comprises an electric gas heater (5) positioned between the second heating stage (E2) and said electrochemical device (1).

11. An installation according to any one of claims 8, 9 or 10, characterized in that it comprises a second recirculation branch (9) of a second outgoing flow from said electrochemical device (1), said second outgoing flow passing through said fifth heat exchanger (50) in said second heating stage (E2) and said fourth heat exchanger (40) included in said first heating stage (E1), and in that said second fluid recirculation branch (9) is an air flow evacuated from said anode (101).

12. Installation according to claim 11, characterized in that said inlet fluid flow of said first pipe (3) comprises a water vapor flow (S), in that said first pipe (3) comprises an inlet flow separator (7) positioned on said first pipe (3), between the inlet of said first inlet pipe (3) and said first heating stage (El), to pass a first part of the inlet flow and a second part of the inlet flow through, respectively, the first heat exchanger (10) and a third (30) heat exchanger of said first heating stage (El), the first and second parts of the flow being gathered upstream of said second heating stage (E2) to pass the whole of the gathered flow into the second heat exchanger (20) of said second heating stage (E2).

13. An installation according to claim 12, characterized in that said first inlet pipe (3) comprises, between said inlet flow separator (7) and said first heat exchanger (10) of said first heating stage (E1), a dihydrogen inlet to enrich with dihydrogen said first part of inlet flow passing through said first heat exchanger (10) of said first heating stage (El).

14. An installation according to claim 8, 9 or 10 combined with claim 1, characterized in that said outgoing flow recirculation branch (9) is an airflow evacuated from said anode (101) of said electrochemical device (1) and in that it comprises a second recirculation branch of a second flow (4) exiting said cathode (102) of said electrochemical device (1), said second flow (4) passing through said second heat exchanger (20) in said second heating stage (E2) and said fourth heat exchanger (40) included in said first heating stage (E1), and in that said second flow of said second recirculation branch (4) is a fuel flow.

15. Installation according to claim 14, characterized in that said fluid inlet flow of said first pipe (3) comprises a water vapor flow (S), in that said first pipe (3) comprises, between said first heat exchanger (10) of said first heating stage (E1) and the second heat exchanger (20) of said second heating stage (E2), a dihydrogen inlet for enriching said water vapor flow (S) of the first pipe (3) downstream of said first heat exchanger (10) with dihydrogen.

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