High-temperature electrolytic cell system optimized by reduced steam supply pressure

Abstract

The system includes a high-temperature electrolyzer (HTE) (1), a first supply line (2) for supplying steam to the cell (1), a first discharge line (4) for discharging dihydrogen from the cell (1), a second discharge line (3) for discharging dioxygen from the cell (1), a first heat exchange module (5) for ensuring heat exchange between the lines (2) and (4), and a steam generator (6) arranged in the line (2) upstream of the module (5) for generating steam from liquid water. The system also includes a module for depressurizing a section (30) of the first supply line (2), the module comprising an expansion device (28) arranged in the first steam supply line (2) upstream of the steam generator (6) and a compressor (29) arranged in the line (2) downstream of the steam generator (6). The invention relates to the fields of high-temperature water electrolysis in solid oxide electrolyte cells (SOECs) and high-temperature water electrolysis in solid oxide fuel cells (SOFCs). The invention is particularly applicable to optimizing the energy consumption of SOEC electrolyzer systems.

Description

Technical Field

[0001] The present invention relates to the field of high-temperature water electrolysis (HTE or HTSE for high-temperature steam electrolysis), and further relates to the fields of solid oxide (SOEC, solid oxide electrolyte cell) and solid oxide fuel cell (SOFC). The present invention is particularly applied to optimize the energy consumption of the SOEC electrolyzer system.

Background Art

[0002] The electrolysis of water is an electrolysis reaction that uses an electric current to decompose water into dioxygen and dihydrogen gas according to the reaction H2O → H2+ 1 / 2 O2

[0003] ​To perform water electrolysis, it is typically advantageous to do so at high temperatures between 600°C and 950°C because some of the energy required for the reaction can be supplied by heat, which is cheaper than electricity, and the activation of the reaction is more effective at high temperatures, eliminating the need for any catalyst. A solid oxide electrolyte cell (SOEC) comprises, in particular, a "cathode," which is a first porous, conductive electrode intended to be supplied with vapor to produce dihydrogen; a "anode," which is a second porous, conductive electrode from which dioxygen produced by the electrolysis of water injected onto the cathode escapes; and a film of solid oxide (high-density electrolyte) sandwiched between the cathode and the anode, which is usually anionically conductive at temperatures above 600°C. By heating this cell to at least this temperature, and by applying a current I between the cathode and the anode, a decrease in water occurs in the cathode, and therefore this generates dihydrogen (H2) in the cathode and dioxygen in the anode. To implement high-temperature electrolysis, it is known that SOEC-type electrolytic cells are used. These electrolytic cells consist of a stack of basic patterns, each containing a solid oxide electrolytic cell. The cell consists of three stacked anode / electrolyte / cathode layers and an interconnect plate made of a metal alloy, also called a bipolar plate or interconnector. The interconnector ensures both the flow of current and the circulation of gas in the vicinity of each cell (injected vapor, hydrogen, and oxygen are extracted in the HTE electrolytic cell, and air and hydrogen are injected, with water extracted in the SOFC cell), and has the function of separating the anode compartment and the cathode compartment, which are gas circulation compartments on the anode and cathode sides of the cell, respectively.

[0004] To perform high-temperature steam electrolysis (HTE), steam H2O is injected into the cathode compartment.

[0005] The current applied to the battery causes the separation of water molecules into vapor form at the junction between the hydrogen electrode (cathode) and the electrolyte, producing dihydrogen gas (H2) and oxygen ions. The dihydrogen is collected and discharged at the hydrogen compartment outlet. The oxygen ions move through the electrolyte and recombine in dioxygen (O2) at the junction between the electrolyte and the oxygen electrode (anode).

[0006] For an effective implementation of electrolysis passing through a stack, the stack is heated to a temperature exceeding 600°C, typically between 600°C and 950°C, the gas supply is started at a constant flow rate, and a power supply is connected between the two terminals of the stack to circulate current I there.

[0007] The yield of electricity-to-hydrogen conversion is key to ensuring the technology's competitiveness. While electricity consumption, strictly speaking, occurs mainly during the electrolysis reaction, nearly 30% of the electrolytic cell's consumption comes from the fluid thermal / hydraulic management system, i.e., the external architecture of the electrolytic cell and the management of fluid and thermal energy within this architecture.

[0008] The evaporation of water used in the electrolytic cell is the greatest energy consumption of this thermal / hydraulic management system. Traditionally, this function has been ensured by an electric steam generator, which consumes 20% of the electrolytic cell's total energy consumption.

[0009] Furthermore, a significant portion of the energy is generally released into the surrounding environment. For example, during the hydrogen drying phase and its compression, it is necessary to cool the water / hydrogen mixture to a high degree to allow for the condensation of water. This condensation generally takes place at temperatures lower than the evaporation temperature of water at the electrolytic cell inlet, which means that a very small portion of this condensation energy is available.

[0010] A document known as Chinese Patent Application Publication No. 110904464A1 (Patent Document 1) describes a system for producing hydrogen by seawater electrolysis based on wind energy at sea. This system includes an evaporator that ensures the generation of steam by heat exchange using the produced dihydrogen. This evaporator is a heat exchanger that is depressurized by a vacuum pump. This system does not seem to solve the aforementioned shortcomings. This system is complex in itself and not very suitable. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Chinese Patent Application Publication No. 110904464A1 Specification [Overview of the project] [Problems that the invention aims to solve]

[0012] Therefore, it is necessary to minimize this consumption by optimizing the fluid architecture and management of the electrolytic cell system.

[0013] The object of the present invention is therefore to propose an optimized high-temperature electrolytic cell system.

[0014] Other objects, features, and advantages of the present invention will become apparent upon consideration of the following description and accompanying drawings. It will also be understood that other advantages may be incorporated. [Means for solving the problem]

[0015] To achieve this objective, according to one embodiment, the present invention provides a system comprising: a high-temperature electrolytic cell (HTE); a first supply line to the electrolytic cell configured to supply steam to the electrolytic cell; a first discharge line to the electrolytic cell configured to discharge dihydrogen from the electrolytic cell; a second discharge line to the electrolytic cell configured to discharge dioxygen from the electrolytic cell; a first heat exchange module configured to ensure heat exchange between the first steam supply line and the first dihydrogen discharge line; and a steam generator located upstream of the first heat exchange module in the first steam supply line and configured to generate steam from liquid water, wherein the system further comprises a module for reducing the pressure of a section of the first supply line, the expansion device located upstream of the steam generator in the first steam supply line; and a compressor located downstream of the steam generator in the first steam supply line.

[0016] Therefore, this system proposes reducing the pressure in a section of the first supply line in order to lower the boiling point of the water circulating in the first supply line. Then, once evaporation of steam occurs in the steam generator, this pressure reduction is preferably compensated for by recompression to atmospheric pressure. The section being depressurized surrounds the steam generator.

[0017] Preferably, the boiling of water is carried out at a temperature lower than the temperature of the heat discharge from the electrolytic cell, and in particular at a temperature lower than the temperatures of dioxygen and dihydrogen, which are favorable for exchange and thus for the utilization of heat discharge.

[0018] Another embodiment relates to the system described above, which includes a module for recovering thermal energy from dihydrogen for a first steam supply line at the outlet of a first heat exchange module, the recovery module comprising a heat pump comprising a fluid circuit configured to receive a heat transfer fluid, a first evaporator located downstream of the first heat exchange module in a first discharge line and configured to transfer the thermal energy of dihydrogen to the heat transfer fluid, a compressor configured to compress the heat transfer fluid, a condenser located upstream of the steam generator in a first steam supply line and configured to transfer thermal energy from the heat transfer fluid to liquid water, and an expansion device configured to expand the heat transfer fluid, wherein the fluid circuit is configured to fluidly connect the first evaporator to the compressor, the compressor to the condenser, the condenser to the expansion device, and the expansion device to the first evaporator.

[0019] This configuration allows for the recovery of the thermal energy of the dihydrogen produced by the electrolytic cell, which contributes to the evaporation of liquid water and thus reduces the system's energy consumption.

[0020] This allows for greater calorific value to be utilized by advantageously coupling a depressurized system using a heat pump. The depletion of dihydrogen produced by the low heat source, i.e., the electrolytic cell, makes it possible to reach temperatures below ambient temperature, which is very favorable for energy balance and hydrogen emissions (and therefore its quality).

[0021] Therefore, this system uses heat from dihydrogen at the outlet of the electrolytic cell, but after the first heat exchange module, the heat discharge of dihydrogen in the evaporator is used at a lower temperature via the active system of the heat pump. The calories recovered from dihydrogen are reinjected upstream of the steam generator at a temperature higher than the evaporation temperature of water.

[0022] The objects, aims, features and advantages of the present invention will best appear from the following detailed description of the latter embodiments illustrated by the accompanying drawings.

Brief Description of the Drawings

[0023] [Figure 1] It is a functional diagram showing the system according to the present invention. [Figure 2] It is a functional diagram showing the system according to an embodiment of the present invention provided with a heat pump. [Figure 3] It is a functional diagram showing the fluid circuit of the heat pump.

Modes for Carrying Out the Invention

[0024] The drawings are given by way of example and are not a limitation of the present invention. The drawings constitute a schematic representation in principle and are intended to facilitate understanding of the present invention and are not necessarily to scale of actual application examples.

[0025] Before commencing a detailed examination of embodiments of the present invention, the following describes optional features which may be used optionally but in relation or alternatively.

[0026] <* According to one example, the compressor 29 is arranged downstream of the first heat exchange module 5.

[0027] It is advantageous for the compression by the compressor 29 to be carried out only on the gas flow and not on the gas / liquid mixture. Carrying out the compression downstream of the first heat exchange module ensures that almost all of the liquid water is converted into steam thereby.

[0028] According to one example, the first heat exchange module 5 comprises a first heat exchanger 5a and a second heat exchanger 5b arranged in series in the first supply line 2, and the compressor 29 is arranged downstream of the first heat exchanger 5a and upstream of the second heat exchanger 5b.

[0029] According to one example, this system includes a first heat exchanger 9 located between a second oxygen exhaust line 3 and a first steam supply line 2, upstream of the steam generator 6.

[0030] Therefore, this first heat exchanger 9 contributes to raising the temperature of the liquid water in front of the steam generator 6 and limits its energy consumption by recovering heat from the dioxygen produced by the electrolytic cell.

[0031] In one example, the expansion device 28 is located upstream of the first heat exchanger 9 in the first supply line 2.

[0032] In one example, the system includes a second supply line 10 to the electrolytic cell, configured to supply air or an oxygen-containing gas to the electrolytic cell.

[0033] In one example, the system includes a second heat exchange module 11 configured to ensure heat exchange between a second air supply line 10 and a second oxygen exhaust line 3.

[0034] Therefore, the second heat exchange module 11 makes it possible to heat the incoming air flow with the heat from the outgoing oxygen flow.

[0035] In one example, the system includes at least one second heat exchanger 16 located downstream of the first evaporator 25a in the first dihydrogen discharge line 4.

[0036] In one example, the heat pump is equipped with a second evaporator 25b.

[0037] In one example, the second evaporator 25b is arranged in series downstream of the first heat exchanger 9 in the fluid circuit 27 of the heat pump.

[0038] In one example, the system includes at least one third heat exchanger 19 located downstream of the second evaporator 25b in the first dihydrogen discharge line 4.

[0039] In one example, the system includes a liquid / gas separator 17 downstream of the second heat exchanger 16 and upstream of the second evaporator 25b.

[0040] In one example, the second heat exchanger 16 is located between the first dihydrogen discharge line 4, which is downstream of the first evaporator 25a, and the second air supply line 10.

[0041] Therefore, the second heat exchanger 16, positioned between the second air supply line 10 and the first dihydrogen discharge line 4, makes it possible to use the residual heat from the dihydrogen to heat the air that enters and goes to the electrolytic cell 1. The exchanger advantageously replaces the air cooler, which makes it possible to avoid the consumption of the air cooler's ventilator, which consumes a lot of energy.

[0042] In one example, the system includes a compressor 12 located in a second air supply line 10 and intended to compress air, preferably upstream of a second heat exchange module 11 and preferably downstream of a second heat exchanger 16.

[0043] Upstream and downstream, inlet and outlet are interpreted as referring to the direction of fluid circulation at a given point.

[0044] A parameter that is "substantially equal to / greater than / less than" a given value also means that the parameter is equal to / greater than / less than that given value, is 10% greater than or less than that value, or even 5% greater than or less than that value.

[0045] The system according to the present invention includes a high-temperature electrolytic cell (HTE) 1. Preferably, the electrolytic cell 1 is of the SOEC (Solid Oxide Electrolyte Battery) type.

[0046] This system includes several supply and discharge lines connected to the electrolytic cell 1. Therefore, a line means a pipe, tube, or set of pipes or tubes that allows for the transport of fluid to and from the electrolytic cell 1.

[0047] The system according to the present invention comprises a first supply line 2 of the electrolytic cell 1 that can supply steam to the electrolytic cell 1. According to one option, the first supply line 2 is configured to supply steam to the electrolytic cell 1, meaning that the first supply line 2 may supply a mixture of steam and other gases, such as air or dihydrogen or carbon dioxide. Upstream of this first supply line 2, steam has not yet been formed, and the first supply line 2 is configured to receive liquid water. According to a preferred option, the first supply line 2 comprises a first portion that receives liquid water and a second portion that receives steam. Preferably, the first portion is located upstream of the steam generator 6, and the second portion is located downstream of the steam generator 6.

[0048] The system according to the present invention comprises a first discharge line 4 that can discharge dihydrogen (H2) from an electrolytic cell 1. Preferably, the first discharge line 4 receives dihydrogen, which is advantageously produced by the electrolytic cell 1. The dihydrogen is in gaseous form. The first discharge line 4 can discharge a mixture of dihydrogen and vapor, which is a mixture referred to as residue, that has not been decomposed by the electrolytic cell 1.

[0049] The system according to the present invention comprises a second discharge line 3 that can discharge dioxygen (O2) from the electrolytic cell 1. Preferably, the second discharge line 3 receives dioxygen, which is advantageously produced by the electrolytic cell 1. The dioxygen is in gaseous form. The second supply line 3 discharges a gaseous dioxygen, such as dioxygen-concentrated air, according to certain options.

[0050] In the following description, without limiting the gases, fluids, or mixtures thereof that can be transported in these lines, the first supply line 2 will be referred to as the first steam supply line 2, the first discharge line 4 as the first dihydrogen discharge line 4, and the second discharge line 3 as the second dioxygen discharge line 3.

[0051] According to one option, the system comprises a first heat exchange module 5 configured to ensure heat exchange between a first steam supply line 2 and a first dihydrogen discharge line 4. This heat exchange module is configured to transfer the calories of dihydrogen from the electrolytic cell 1 to the water intended to be supplied to the electrolytic cell 1. The flow of dihydrogen gas ensures a temperature rise in the water flow, while simultaneously allowing for the cooling of the discharged dihydrogen flow, which is advantageously discharged and / or compressed, taking into consideration its utilization.

[0052] The first heat exchange module 5, according to one embodiment, comprises at least one heat exchanger 5a configured to ensure heat transfer from dihydrogen to vapor. According to one preferred embodiment, the first heat exchange module 5 comprises two heat exchangers 5a, 5b arranged in series between a first supply line 2 and a first discharge line 4. This arrangement makes it possible to provide a second heat exchanger 5b adapted to the temperature of dihydrogen at the outlet of the electrolytic cell 1, which is conventionally about 700°C, and a more conventional first heat exchanger 5a adapted to the temperature of dihydrogen after it has been sent to the heat exchanger, which is conventionally about 330°C. In this way, these components are optimized for temperature and the heat transfer to be achieved.

[0053] The system according to the present invention includes a steam generator 6. The steam generator 6 is intended to generate steam from liquid water. Energy is supplied to the steam generator 6 to ensure that the temperature of the liquid water rises above its evaporation temperature. The steam generator 6 is a component that constitutes the main energy consumption of the electrolytic cell system according to the art. The steam generator 6 is located in a first steam supply line 2.

[0054] According to a first aspect of the present invention illustrated in Figure 1, the system includes a module for reducing the pressure in a section 30 of a first supply line 2. This pressure reduction module is located in the first steam supply line 2. The pressure reduction module includes an expansion device 28 and a compressor 29. Advantageously, the expansion device 28 is located upstream of the steam generator 6 to reduce the pressure in the first supply line 2 upstream of the steam generator 6, and preferably the pressure in the steam generator 6. This pressure reduction makes it possible to lower the evaporation temperature of the liquid water in the steam in the steam generator 6. Advantageously, the pressure reduction module includes a compressor 29 located downstream of the steam generator 6. The compressor 29 is preferably located in the first supply line 2 at a point where substantially all of the water circulating in the first supply line is in the steam phase. According to one option, the compressor 29 is located downstream of the first heat exchange module 5. In practice, compression is more effective when the fluid flow consists only of gas, in this case only of steam. Therefore, it is preferable to overheat the steam in the first heat exchange module 5 to ensure that no liquid water is present in the flow. Preferably, the compressor 29 is located downstream of the first heat exchanger 5a and upstream of the second heat exchanger 5b of the first heat exchange module 5. In practice, this positioning before the second heat exchanger 5b limits the thermal stress on this component and, therefore, limits its cost. Furthermore, compression after the second heat exchanger 5b may cause the temperature at the inlet of the electrolytic cell 1 to exceed 700°C.

[0055] As an example, a module for reducing the pressure in section 30 of the first supply line 2 guarantees a pressure reduction of 200 millibars. The evaporation temperature of the liquid water is thus reduced to 60°C. Such a pressure reduction is also compensated for by the compressor 29 without very high energy consumption. Thus, it is energy efficient.

[0056] Section 30 of the first supply line 2, which is depressurized by a depressurization module, extends between the expansion device 28 and the compressor 29 and advantageously includes a steam generator 6.

[0057] According to one embodiment, the system comprises a first heat exchanger 9 located in a first steam supply line 2 and a second dioxygen discharge line 3. The first heat exchanger 9 is preferably located upstream of the generator 6 in the first supply line 2. The first heat exchanger 9 is located in a first portion of the first supply line 2. Preferably, the first heat exchanger 9 is located in a first section 30, i.e., between the expansion device 28 and the compressor 29. The first heat exchanger 9 is configured to ensure that the calories removed in the dioxygen flow discharged from the electrolytic cell 1 and circulating in the second discharge line 3 are transferred to the steam supply line 2. The first heat exchanger 9 is configured to transfer the thermal energy of the dioxygen at the outlet of the electrolytic cell 1 to liquid water upstream of the steam generator 6.

[0058] According to one embodiment, the system includes a second supply line 10 that can supply air to the electrolytic cell 1. Preferably, the second supply line 10 receives air. According to one option, the second supply line 10 is configured to supply air to the electrolytic cell 1, thereby meaning that the second supply line 10 can supply air, for example, a mixture of gases, thereby enabling sweeping of the cells in the electrolytic cell 1 and removing the dioxygen produced by the electrolytic cell 1.

[0059] According to this embodiment, it is advantageous for the system according to the present invention to include a second heat exchange module 11 configured to ensure heat exchange between a second air supply line 10 and a second dioxygen discharge line 3. This heat exchange module 11 is configured to transfer the calories of dioxygen from the electrolytic cell 1 to the air intended to supply to the electrolytic cell 1. The flow of dioxygen gas ensures a temperature rise in the air flow, which also allows for cooling of the discharged dioxygen flow.

[0060] The second heat exchange module 11, according to one embodiment, comprises at least one heat exchanger 11a configured to ensure heat transfer from dioxygen to air. According to a preferred embodiment, the second heat exchange module 11 comprises two heat exchangers 11a, 11b arranged in series between a second supply line 10 and a second discharge line 3. This arrangement makes it possible to provide a second heat exchanger 11b adapted to the temperature of dioxygen at the outlet of the electrolytic cell 1, which is conventionally about 700°C, and a more conventional first heat exchanger 11a adapted to the temperature of dioxygen after it has been sent to the heat exchanger, which is conventionally about 330°C. In this way, these components are optimized for temperature and the heat transfer to be achieved.

[0061] The system preferably includes a compressor 12 located in a second supply line 10 intended to supply air. The compressor 12, if present, is preferably located upstream of a second heat exchange module 11. The compressor 12 is intended to ensure the compression of the air intended to be supplied to the electrolytic cell 1. The compression of the air advantageously contributes to raising the temperature of the air before it enters the electrolytic cell 1.

[0062] According to one embodiment, the system includes means for processing the generated dihydrogen flow. The dihydrogen produced by the electrolytic cell 1 and emerging therethrough through the first discharge line 4 initially has a very high temperature corresponding to the reaction temperature of the electrolytic cell 1. However, considering its use, this dihydrogen should preferably be brought to a temperature close to the ambient temperature. Furthermore, the dihydrogen discharged from the electrolytic cell 1 through the first discharge line 4 may contain vapors removed along with the dihydrogen flow. Therefore, it is also preferable to separate the dihydrogen from any vapors that may have been removed along with it by discharging it.

[0063] The system according to the present invention is advantageous in that it comprises at least one first processing stage intended for this purpose for the discharge and / or compression of the dihydrogen produced.

[0064] According to one option, the first processing stage includes a second heat exchanger 16. The second heat exchanger 16 is preferably located downstream of the first heat exchange module 5 in the first discharge line 4. According to the first option, this second heat exchanger 16 is an air cooler 16, i.e., a heat exchanger between a fluid and a gas, in which case the gas is driven by a fan. According to another option, this heat exchanger is a standard cooler, i.e., a cooler without a fan, but this solution is less effective. According to an option not shown in Figure 1, the second heat exchanger 16 ensures heat exchange between the fluid and a gas, which is air, in particular intended to be supplied to the electrolytic cell 1. This arrangement makes it possible to both avoid an air cooler and its energy-consuming fan, and to increase the waste heat from the dihydrogen circulating in the first discharge line 4 to the air supplied to the electrolytic cell 1.

[0065] Therefore, the system includes a second heat exchanger 16 located between the first dihydrogen discharge line 4 and the second air supply line 10. The fluid connection 110 is thus connected between the outlet of the second heat exchanger and the inlet of the compressor 12. In this way, the air intended to enter the electrolytic cell 1 is preheated by the transfer of calories from the dihydrogen. Preferably, the arrangement of the second heat exchanger corresponds to the arrangement of the air cooler 16 described above.

[0066] The first processing stage preferably includes a liquid / gas separator 17 located downstream of the second heat exchanger 16. The separator 17 makes it possible to separate the liquid water obtained as a result of cooling the steam in the second heat exchanger 16 below its condensation point from the gaseous dihydrogen.

[0067] In a preferred option, the system includes a second processing stage located downstream of the first processing stage in the first discharge line 4. This second processing stage makes it possible to complete the discharge of dihydrogen. This second processing stage advantageously includes a third heat exchanger 19, which may be a standard cooler as in the case of the first stage, and an air cooler, i.e., a heat exchanger 19 between the fluid (dihydrogen) and the air intended to be supplied to the electrolytic cell 1. The third exchanger 19 is located in the first dihydrogen discharge line 4, preferably downstream of the second heat exchanger 16, and in the second air supply line 10, preferably upstream of the second heat exchanger 16. The second stage preferably includes a liquid / gas separator 20. Preferably, the system includes a compressor 18 between the first and second processing stages, configured to enable the second processing by the third heat exchanger 19 by pre-raising the temperature of the mixture so that it can be cooled again.

[0068] Preferably, liquid water is recycled from the first and / or second processing stages, if present, by being returned to the first steam supply line 2 through a water recycling line 21. This water recycling line is preferably fluidically connected to the first supply line 2 upstream of the steam generator 6, preferably upstream of the first heat exchanger 9, i.e., preferably in the first portion of the first supply line 2. Dihydrogen is used on its own and, in particular, stored after conventional processing.

[0069] According to one option, the system includes at least one supplementary heat source configured to heat the steam entering the electrolytic cell 1 to a predetermined target temperature. This supplementary heat source is advantageously located in the first steam supply line 2, preferably downstream of the first heat exchange module 5. This supplementary heat source is, for example, an electric heater 14.

[0070] According to one option, the system includes at least one supplementary heat source configured to heat the air entering the electrolytic cell 1 to a predetermined target temperature. This supplementary heat source is advantageously located in the second air supply line 10, preferably downstream of the second heat exchange module 11. This supplementary heat source is, for example, an electric heater 13.

[0071] According to one embodiment, the system includes at least one pump 15 configured to move liquid water in a first portion of the first supply line 2 upstream of the steam generator 6 in the first steam supply line 2.

[0072] Preferably, this system includes a pump 22 in the water recycling line 21. The pump 22 is configured to circulate the water recycling line 21 and move the liquid water generated from the gas / liquid separator 20.

[0073] Preferably, the electrolytic cell 1 is fluidically connected to a first steam supply line 2. The first steam supply line 2 ensures fluid connections to components located upstream of the electrolytic cell 1 in the first supply line 2. The following description is made by starting from upstream of the electrolytic cell 1 and following the direction of circulation in the first supply line. The first supply line 2 ensures fluid connections from the expansion device 28 to the first heat exchanger 9, then from the first heat exchanger 9 to the steam generator 6, then from the steam generator 6 to the first heat exchange module 5, preferably the first heat exchanger 5a, then from the first heat exchanger 5a to the compressor 29, then from the compressor 29 to the second heat exchanger 5b, then from the second heat exchanger 5b to the electric heater 14, and finally from the electric heater 14 to the electrolytic cell 1.

[0074] Preferably, the electrolytic cell 1 is fluidly connected to a first dihydrogen discharge line 4. The first discharge line 4 ensures fluid connections to components located downstream of the electrolytic cell 1 in the first discharge line. The following description is made by starting from the electrolytic cell 1 and following the direction of circulation from the electrolytic cell 1 in the first discharge line 4. The first discharge line 4 ensures fluid connections between the electrolytic cell 1 and the first heat exchange module 5, more preferably from the second heat exchanger 5b to the first heat exchanger 5a, then from the first heat exchanger 5 to the second heat exchanger 16, then from the second heat exchanger 16 to the liquid / gas separator 17, then from the liquid / gas separator 17 to the compressor 18, then, advantageously, from the compressor 18 to the third heat exchanger 19, and then from the second heat exchanger 19 to the liquid / gas separator 20.

[0075] Preferably, the electrolytic cell 1 is fluidically connected to one of the second two-oxygen discharge lines 3. The second discharge line 3 ensures fluid connections to components located downstream of the electrolytic cell 1 in the second discharge line 3. The following description is made by starting from the electrolytic cell 1 and following the direction of circulation from the electrolytic cell 1 in the second discharge line 3. The second discharge line 3 ensures fluid connections between the electrolytic cell 1 and the second heat exchange module 11, more preferably to the second heat exchanger 11b, then from the second heat exchanger 11b to the first heat exchanger 11a, and then from the first heat exchanger 11a to the first heat exchanger 9.

[0076] Preferably, the electrolytic cell 1 is fluidically connected to a second air supply line 10. The second supply line 10 ensures fluid connections to components located upstream of the electrolytic cell 1 in the second supply line 10. The second supply line 10 ensures fluid connections from the compressor 12 to the first heat exchanger 11a, then from the first heat exchanger 11a to the second heat exchanger 11b, then from the second heat exchanger 11b to the electric heater 13, and then from the electric heater 13 to the electrolytic cell 1. According to an option not shown, upstream of the compressor 12, the second supply line 10 ensures a fluid connection from the second heat exchanger 16 to the compressor 12.

[0077] This system is described below and features fluid connections that form part of the different supply lines 2, 10 and discharge lines 3, 4 of this system.

[0078] With respect to the first supply line 2, it is advantageously equipped with a fluid connection A connected to the inlet of the pump 15.

[0079] Advantageously, the first supply line 2 includes a fluid connection B, which is connected between the outlet of the pump 15 and the inlet of the expansion device 28.

[0080] Advantageously, the first supply line 2 includes a fluid connection C connected between the outlet of the expansion device 28 and the inlet of the first heat exchanger 9.

[0081] Advantageously, the first supply line 2 includes a fluid connection D connected between the outlet of the first heat exchanger 9 and the inlet of the steam generator 6.

[0082] Advantageously, the first supply line 2 includes a fluid connection E connected between the outlet of the steam generator 6 and the inlet of the first heat exchanger 5a of the heat exchange module 5.

[0083] Advantageously, the first supply line 2 includes a fluid connection F connected between the outlet of the first heat exchanger 5a and the inlet of the compressor 29.

[0084] Advantageously, the first supply line 2 includes a fluid connection G connected between the outlet of the compressor 29 and the inlet of the second heat exchanger 5b.

[0085] Advantageously, the first supply line 2 includes a fluid connection H connected between the outlet of the second heat exchanger 5b and the inlet of the electric heater 14.

[0086] Advantageously, the first supply line 2 includes a fluid connection I connected between the outlet of the electric heater 14 and the inlet of the electrolytic cell 1.

[0087] With respect to the first discharge line 4, it is advantageous that it includes a first fluid connection J between the outlet of the electrolytic cell 1 and the inlet of the second heat exchanger 5b of the first heat exchange module 5.

[0088] Advantageously, the first discharge line 4 is equipped with a fluid connection K between the outlet of the second heat exchanger 5b of the first heat exchange module 5 and the inlet of the first heat exchanger 5a of the first heat exchange module 5.

[0089] Advantageously, the first discharge line 4 is equipped with a fluid connection L between the outlet of the first heat exchanger 5a and the inlet of the second heat exchanger 16.

[0090] Advantageously, the first discharge line 4 is equipped with a fluid connection M between the outlet of the second heat exchanger 16 and the inlet of the separator 17.

[0091] Advantageously, the first discharge line 4 includes a fluid connection N between the outlet of the separator 17 and the inlet of the compressor 18.

[0092] Advantageously, the first discharge line 4 includes a fluid connection O between the outlet of the compressor 18 and the inlet of the third heat exchanger 19.

[0093] Advantageously, the first discharge line 4 is equipped with a fluid connection P between the outlet of the third heat exchanger 19 and the inlet of the separator 20.

[0094] Advantageously, the first discharge line 4 is equipped with a fluid connection Q that ensures the outlet of dihydrogen from the separator 20.

[0095] With respect to the second oxygen discharge line, it is advantageous that it includes a fluid connection 100 between the outlet of the electrolytic cell 1 and the inlet of the second heat exchanger 11b of the second heat exchange module 11.

[0096] Advantageously, the second discharge line 3 includes a fluid connection 101 between the outlet of the second heat exchanger 11b and the inlet of the first heat exchanger 11a of the second heat exchange module 11.

[0097] Advantageously, the second discharge line 3 includes a fluid connection 102 between the outlet of the first heat exchanger 11a and the inlet of the first heat exchanger 9.

[0098] Advantageously, the second discharge line 3 includes a fluid connection 103 between the outlet of the first heat exchanger 9 and the outside.

[0099] With respect to the second air supply line 4, it includes a fluid connection 110 between the outlet of the alternative second heat exchanger 16 and the inlet of the compressor 12, according to options not shown.

[0100] Advantageously, the second supply line 4 includes a fluid connection 111 between the outlet of the compressor 12 and the inlet of the first heat exchanger 11a of the second heat exchange module 11.

[0101] Advantageously, the second supply line 4 includes a fluid connection 112 between the outlet of the first heat exchanger 11a and the inlet of the second heat exchanger 11b of the second heat exchange module 11.

[0102] Advantageously, the second supply line 4 includes a fluid connection 113 between the outlet of the second heat exchanger 11b and the inlet of the electric heater 13.

[0103] Advantageously, the second supply line 4 includes a fluid connection 114 between the outlet of the electric heater 13 and the inlet of the electrolytic cell 1.

[0104] In operation, liquid water arrives in the first steam supply line 2, more specifically in the first section through fluid connection A. Fluid connection A is advantageously connected to the inlet of the pump 15 that moves the liquid water. The water recycling line 21 is advantageously fluidally connected to the first supply line 2 at fluid connection B, which ensures a fluid connection to the inlet of the expansion device 28 at the pump outlet 15. The recycled water and liquid water enter the expansion device 28. In the expansion device 28, the pressure is reduced. For example, the expansion device 28 ensures a pressure reduction of 200 millibars in the first supply line. Preferably, the first depressurized supply line 2 extends between the expansion device 28 and the compressor 29. The water emerges from the depressurized expansion device 28 through fluid connection C and preferably directly enters the first heat exchanger 9. In the first heat exchanger 9, the temperature of the water rises by recovering calories from the oxygen circulating in the first heat exchanger 9. The heated water exits the first heat exchanger 9, passes through the fluid connection D, and preferably enters the steam generator 6 directly, i.e., without passing through any intermediate members. This liquid water is converted into steam by the steam generator 6.

[0105] According to the present invention, the energy required to be supplied by the steam generator 6 for the conversion of liquid water to steam is reduced thanks to the depressurization module, in particular thanks to the expansion device 28 which enables a reduction in the evaporation temperature of water, and also advantageously thanks to the first heat exchanger 9 which ensures a rise in the temperature of the liquid water by recovering thermal energy from dihydrogen and dioxygen produced by the electrolytic cell 1.

[0106] Steam exits the steam generator 6 through fluid connection E and preferably directly enters the first heat exchange module 5, preferably the first heat exchanger 5a. This steam is heated in the first heat exchanger 5a by recovering calories from the dihydrogen circulating in the first heat exchanger 5a. This overheated steam exits the first heat exchanger 5a through fluid connection F and preferably directly enters the compressor 29. The compressor 29 allows the pressure in the downstream supply line 2 to increase in order to enable the operation of the electrolytic cell 1. The steam pressurized by the compressor 29 exits through fluid connection G and preferably directly enters the second heat exchanger 5b. This steam is heated again in the second heat exchanger 5b by recovering calories from the dihydrogen circulating in the second heat exchanger 5b. This overheated steam exits the second heat exchanger 5b through fluid connection H and, if necessary, preferably directly enters the electric heater 14. The electric heater 14 ensures the minimum possible temperature rise necessary for the vapor to reach a predetermined target temperature before entering the electrolytic cell 1. The vapor exits the electric heater 14 through the fluid connection I and, preferably directly, enters the electrolytic cell 1.

[0107] The electrolytic cell 1 is supplied with current at a predetermined voltage and intensity that ensures electrolysis and, therefore, the production of dihydrogen and dioxygen.

[0108] Dihydrogen exits the electrolytic cell 1 through the first discharge line 4 and, preferably directly, enters the first heat exchange module 5, preferably the second heat exchanger 5b, through the fluid connection J. This dihydrogen exits the electrolytic cell 1 in a high-temperature gaseous state, but its temperature needs to be reduced in order to use and / or store it. The calories from this dihydrogen are therefore recovered by the first supply line 2, more specifically by the steam circulating therein. In the second heat exchanger 5b, the temperature of the dihydrogen is reduced by the transfer of calories to the steam circulating in the second heat exchanger 5b. The cooled dihydrogen exits the second heat exchanger 5b through the fluid connection K and, preferably directly, enters the first heat exchanger 5a. In the first heat exchanger 5a, the temperature of the dihydrogen is reduced again by the transfer of calories to the steam circulating in the first heat exchanger 5a. The cooled dihydrogen exits the first heat exchanger 5a through fluid connection L and preferably directly into the second heat exchanger 16. The dihydrogen exits the second heat exchanger 16 through fluid connection M and preferably directly into the liquid / gas separator 17, which ensures the condensation of this dihydrogen. The dihydrogen exits the liquid / gas separator 17 through fluid connection N and, if necessary, experiences another compression, considering another condensation. In this case, the dihydrogen exits the liquid / gas separator 17 through fluid connection N and preferably directly into the compressor 18, and exits the compressor 18 through fluid connection O and preferably directly into the third heat exchanger 19, which ensures the cooling of this dihydrogen. The dihydrogen exits the third heat exchanger 19 through fluid connection P and preferably directly into the liquid / gas separator 20, which ensures the condensation of this dihydrogen. The condensed dihydrogen exits the liquid / gas separator 20 through the fluid connection Q, but can be used or stored. The condensed liquid water recovered from the liquid / gas separators 17 and 20 can be recycled in the first steam supply line 2 through the fluid connection using the water recycling line 21.

[0109] The dioxygen produced by the electrolytic cell 1 exits the electrolytic cell 1 via the second discharge line 3 and, preferably directly, enters the second heat exchange module 11, and preferably the second heat exchanger 11b, through the fluid connection 100. The dioxygen exits the electrolytic cell 1 in a high-temperature gaseous state, but its temperature needs to be reduced for discharge into the air. The calories from the dioxygen are therefore advantageously restored by the second supply line 10, more specifically by the air circulating therein. In the second heat exchanger 11b, the temperature of the dioxygen is reduced by the transfer of heat to the air circulating in the second heat exchanger 11b. The cooled dioxygen exits the second heat exchanger 11b via the fluid connection 101 and, preferably directly, enters the first heat exchanger 11a. In the first heat exchanger 11a, the temperature of the dioxygen is reduced again by the transfer of heat to the air circulating in the first heat exchanger 11a. The cooled dioxygen exits the first heat exchanger 11a through the fluid connection 102 and, advantageously, preferably directly, enters the first heat exchanger 9 of the recovery module. By being sent into the first heat exchanger 9, the temperature of the dioxygen is again reduced by the transfer of heat to the liquid water circulating in the first heat exchanger 9. The air exits the first heat exchanger through the fluid connection 103 and is discharged into the air.

[0110] According to one option, air is supplied to the electrolytic cell 1. This air arrives through a second supply line 10. Advantageously, this air passes through a second heat exchanger 16 that replaces the air cooler, recovering calories from the dihydrogen circulating in the heat exchanger 16. This first heat exchange ensures the first heating of the air. The air exits the second heat exchanger 16 through a fluid connection 110 and preferably directly enters the compressor 12. According to the illustrated option, the air is compressed by the compressor 12 and its temperature rises. The air enters the compressor 12 through the fluid connection 110. The air exits the compressor 12 through a fluid connection 111 and preferably directly enters the second heat exchange module 11, preferably the first heat exchanger 11a. Air is heated in the first heat exchanger 11a by recovering calories from the oxygen circulating in the first heat exchanger 11a. The excess superheated air exits the first heat exchanger 11a through the fluid connection 112 and preferably directly enters the second heat exchanger 11b. This air is heated again in the second heat exchanger 11b by recovering calories from the oxygen circulating in the second heat exchanger 11b. The excess superheated air exits the second heat exchanger 11b through the fluid connection 113 and, if necessary, preferably directly enters the electric heater 13. The electric heater 13 ensures a final temperature rise, which may be necessary, for the air to reach a predetermined target temperature before entering the electrolytic cell 1. The air exits the electric heater 13 through the fluid connection 114 and preferably directly enters the electrolytic cell 1.

[0111] According to a second aspect of the present invention, illustrated in Figure 2 and which may or may not be combinable with the first aspect, the system comprises a module that recovers thermal energy from dihydrogen for the first steam supply line 2 at the outlet of the heat exchange module 5.

[0112] According to one option, this recovery module includes a heat pump located between the first dihydrogen discharge line 4 and the first steam supply line 2. The heat pump is configured to transfer thermal energy from dihydrogen to liquid water.

[0113] The heat pump comprises a condenser 23, an expansion device 24, at least one first evaporator 25a, and a compressor 26.

[0114] The heat pump is equipped with a fluid circuit 27 that can receive a heat transfer fluid.

[0115] The heat transfer fluids are, for example, 1234yf, or 2,3,3,3-tetrafluoropropene (HFO-1234yf), R245FA pentafluoropropane, and R290 propane, which are fluids conventionally used in heat pumps.

[0116] Preferably, the condenser 23 is located between the fluid circuit 27 and the first supply line 2, and preferably, the condenser 23 is located downstream of the first heat exchanger 9 in the first supply line 2.

[0117] The fluid circuit 27 is preferably a closed circuit to ensure fluid connections between the components of the heat pump.

[0118] According to one embodiment, the fluid circuit 27 includes a fluid connection 200 connected between the outlet of the compressor 26 and the inlet of the condenser 23. Advantageously, the fluid circuit 27 includes a fluid connection 201 connected between the outlet of the condenser 23 and the inlet of the expansion device 24. Advantageously, the fluid circuit 27 includes a fluid connection 202 connected between the outlet of the expansion device 24 and the inlet of the first evaporator 25a.

[0119] According to the option illustrated in Figure 2, the heat pump comprises two evaporators 25a and 25b arranged in series between the expansion device 24 and the compressor 26 in the fluid circuit. The fluid circuit 27 comprises a fluid connection 203 connected between the outlet of the first evaporator 25a and the inlet of the second evaporator 25b. According to this option, advantageously, the fluid circuit 27 comprises a fluid connection 204 connected between the outlet of the second evaporator 25b and the inlet of the compressor 26.

[0120] According to options not shown, the heat pump comprises two evaporators 25a, 25b arranged in parallel between the condenser 23 and the compressor 26 in the fluid circuit. Preferably, the heat pump comprises two expansion devices 24 arranged in parallel upstream of each evaporator 25a, 25b in the fluid circuit. Advantageously, the fluid circuit 27 comprises a fluid connection 201 connected between the outlet of the condenser 23 and the inlet of the expansion device 24. Advantageously, the fluid circuit 27 comprises a fluid connection 202 connected between the outlet of the expansion device 24 and the inlet of the first evaporator 25a. Advantageously, the fluid circuit 27 comprises a fluid connection 203 connected between the outlet of the first evaporator 25a and the inlet of the compressor 26. Advantageously, in parallel, the fluid circuit 27 comprises a fluid connection connected between the outlet of the condenser 23 and the inlet of the second expansion device. Advantageously, the fluid circuit 27 includes a fluid connection between the outlet of the second expansion device and the inlet of the second evaporator 25b. Advantageously, the fluid circuit 27 also includes a fluid connection between the outlet of the second evaporator 25b and the inlet of the compressor 26. Preferably, the fluid connections 203 extending from the two evaporators 25a, 25b intersect before the inlet of the compressor 26 to ensure a single inlet at the compressor 26.

[0121] According to the present invention, the condenser 23 of the heat pump is located upstream of the steam generator 6 in the first steam supply line 2 to deliver calories from the heat transfer fluid to the liquid water circulating in the first supply line 2, more specifically in the first portion of the first supply line 2, which is upstream of the steam generator 6. Preferably, the condenser 23 is located in section 30 of the first supply line 2. Preferably, the condenser 23 is located downstream of the expansion device 28, more specifically downstream of the first heat exchanger 9. The condenser 23 is preferably located downstream of the first heat exchanger 9 and upstream of the steam generator 6. The outlet of the first heat exchanger 9 is fluidically connected to the inlet of the condenser 23 through fluid connection D'. The outlet of the condenser 23 is fluidically connected to the inlet of the steam generator 6 through fluid connection D''.

[0122] According to the present invention, the first evaporator 25a of the heat pump is located in the first dihydrogen discharge line 4, preferably downstream of the first heat exchange module 5, and more specifically downstream of the first heat exchanger 5a of the first heat exchange module 5. Preferably, the first evaporator 25a is located upstream of the first processing stage, i.e., upstream of the optional but not shown second heat exchanger 16 in Figure 2. The first evaporator 25a ensures the transfer of energy between the dihydrogen circulating in the first discharge line 4 and the heat transfer fluid circulating in the fluid circuit 27 of the heat pump.

[0123] According to the option illustrated in Figure 2, the outlet of the first heat exchanger 5a of the first heat exchange module 5 is fluidically connected to the inlet of the first evaporator 25a via fluid connection L'. The outlet of the first evaporator 25a is fluidically connected to the inlet of the separator 17 via fluid connection M'. According to an option not shown, the outlet of the first evaporator 25a is fluidically connected to the inlet of the second heat exchanger 16 via an unshown fluid connection, and the outlet of the second heat exchanger 16 is fluidically connected to the inlet of the separator 17 via an unshown fluid connection.

[0124] According to one embodiment, the heat pump includes a second heat exchanger 25b. The second heat exchanger 25b is located downstream of the first dihydrogen processing stage and, advantageously, upstream of the second dihydrogen processing stage. Optionally, a second evaporator 25a is located upstream of a third heat exchanger 19 (not shown in Figure 2), preferably downstream of the compressor 18.

[0125] According to the option illustrated in Figure 2, the outlet of the compressor 18 is fluidically connected to the inlet of the second evaporator 25b via fluid connection O'. The outlet of the second evaporator 25b is fluidically connected to the inlet of the separator 20 via fluid connection P'. According to an option not shown, the outlet of the second evaporator 25b is fluidically connected to the inlet of the third heat exchanger 19 via an unshown fluid connection, and the outlet of the third heat exchanger 19 is fluidically connected to the inlet of the separator 17 via an unshown fluid connection.

[0126] According to another option not shown, the heat pump has a single evaporator 25a, whose outlet is connected directly to the inlet of the compressor 26, passing through a fluid connection 203.

[0127] According to the present invention, it becomes possible to utilize the waste heat of the system, and more specifically, to utilize the heat discharge of the generated dihydrogen. The heat pump is an active system that allows the removed calories to be reinjected into the generated dihydrogen at a temperature higher than the evaporation temperature of water, upstream of the steam generator.

[0128] The following table gives, as an example, the temperature and pressure at a specific point in the system according to the present invention, as illustrated in Figure 1.

[0129] [Table 1]

[0130] According to this solution in the first aspect of the present invention, a gain of approximately 7% is possible for the overall yield of the electric conversion to dihydrogen.

[0131] The present invention is not limited to the embodiments described above, but extends to all embodiments included in the claims. [Explanation of Symbols]

[0132] 1 electrolytic cell 2 Steam supply line 3. Oxygen exhaust line 4. Dihydrogen Emission Line 5a First heat exchanger of the first heat exchange module 5b Second heat exchanger of the first heat exchange module 6. Steam generator 7 Compressor 9. First heat exchanger 10 Air supply line 11a First heat exchanger of the second heat exchange module 11b Second heat exchanger of the second heat exchange module 12 Compressors 13 Electric heater 14 Electric heater 15 pumps 16. Second heat exchanger 17. Liquid / Gas Separator 18 Compressor 19. Third heat exchanger 20 Liquid / Gas Separator 21 Water Recycling Line 22 pumps 23 Condenser 24 Inflation Devices 25a First evaporator 25b Second evaporator 26 Compressor 27 Fluid circuit 28. Inflation Devices 29 Compressor 30 sections Fluid connection to pump 15 B Fluid connection between pump 15 and expansion device 28 C Fluid connection between expansion device 28 and first heat exchanger 9 D Fluid connection between the first heat exchanger 9 and the steam generator 6 E Fluid connection between steam generator 6 and first heat exchanger 5a F Fluid connection between the first heat exchanger 5a and the compressor 29 G Fluid connection between compressor 29 and second heat exchanger 5b H Fluid connection between the second heat exchanger 5b and the heater 14 I. Fluid connection between heater 14 and electrolytic cell 1 J Fluid connection between electrolytic cell 1 and second heat exchanger 5b K Fluid connection between the second heat exchanger 5b and the first heat exchanger 5a L Fluid connection between the first heat exchanger 5a and the air cooler 16 M Fluid connection between air cooler 16 and separator 17 N Fluid connection between separator 17 and compressor 18 O Fluid connection between compressor 18 and air cooler 19 P Fluid connection between air cooler 19 and separator 20 Q Fluid connection from separator 20 D' Fluid connection between the first heat exchanger 9 and the condenser 23 D" Fluid connection between condenser 23 and steam generator 6 L' Fluid connection between the first heat exchanger 5a and the first evaporator 25a M' Fluid connection between the first evaporator 25a and the separator 17 Fluid connection between compressor 18 and second evaporator 25b P' Fluid connection between the second evaporator 25b and the separator 20 100 Fluid connection between electrolytic cell 1 and second heat exchanger 11b 101 Fluid connection between the second heat exchanger 11b and the first heat exchanger 11a 102 Fluid connection between the first heat exchanger 11a and the first heat exchanger 9 110 Compressor 12 inlet fluid connection 111 Fluid connection between compressor 12 and first heat exchanger 11a 112 Fluid connection between the first heat exchanger 11a and the second heat exchanger 11b 113 Fluid connection between the second heat exchanger 11b and the heater 13 114 Fluid connection between heater 13 and electrolytic cell 1 200 Fluid connection between compressor 26 and condenser 23 201 Fluid connection between condenser 23 and expansion device 24 202 Fluid connection between expansion device 24 and first evaporator 25a 203 Fluid connection between the first evaporator 25a and the second evaporator 25b 204 Fluid connection between the second evaporator 25b and the compressor 26

Claims

1. High-temperature electrolytic cell (HTE) (1), A first steam supply line (2) of the electrolytic cell (1) is configured to supply steam to the electrolytic cell (1), A first hydrogen discharge line (4) of the electrolytic cell (1) is configured to discharge hydrogen from the electrolytic cell (1), A second oxygen discharge line (3) of the electrolytic cell (1) is configured to discharge oxygen from the electrolytic cell (1), A first heat exchange module (5) is configured to ensure heat exchange between the first steam supply line (2) and the first hydrogen discharge line (4), A steam generator (6) is located upstream of the first heat exchange module (5) in the first steam supply line (2) and is configured to generate steam from liquid water, A system equipped with, The system is characterized by comprising a module for reducing the pressure of a section (30) of the first steam supply line (2), the module comprising an expansion device (28) located upstream of the steam generator (6) in the first steam supply line (2), and a compressor (29) located downstream of the steam generator (6) in the first steam supply line (2).

2. The system according to claim 1, wherein the compressor (29) is located downstream of the first heat exchange module (5).

3. The system according to claim 2, wherein the first heat exchange module (5) comprises a first heat exchanger (5a) and a second heat exchanger (5b) of the first heat exchange module arranged in series, and the compressor (29) is located downstream of the first heat exchanger (5a) and upstream of the second heat exchanger (5b).

4. The system according to any one of claims 1 to 3, further comprising a first heat exchanger (9) located between the second oxygen discharge line (3) and the first steam supply line (2) and upstream of the steam generator (6).

5. The system according to claim 4, wherein the expansion device (28) is located upstream of the first heat exchanger (9) in the first steam supply line (2).

6. The system according to any one of claims 1 to 5, further comprising a second air supply line (10) for the electrolytic cell (1) configured to supply air to the electrolytic cell (1).

7. The system according to claim 6, further comprising a second heat exchange module (11) configured to ensure heat exchange between the second air supply line (10) and the second oxygen discharge line (3).

8. The first heat exchange module (5) is connected to the first steam supply line (2) and includes a module for recovering thermal energy from the hydrogen, the recovery module is A fluid circuit (27) configured to receive a heat transfer fluid, A first evaporator (25a) is located downstream of the first heat exchange module (5) in the first hydrogen discharge line (4) and is configured to transfer the thermal energy from the hydrogen to the heat transfer fluid, A compressor (26) configured to compress the heat transfer fluid, A condenser (23) is located upstream of the steam generator (6) in the first steam supply line (2) and is configured to transfer the thermal energy from the heat transfer fluid to the liquid water, An expansion device (24) configured to expand the heat transfer fluid, It is equipped with a heat pump, The system according to any one of claims 1 to 7, wherein the fluid circuit (27) is configured to fluidly connect the first evaporator (25a) to the compressor (26), the compressor (26) to the condenser (23), the condenser (23) to the expansion device (24), and the expansion device (24) to the first evaporator (25a).

9. The system according to claim 8, further comprising at least one second heat exchanger (16) located downstream of the first evaporator (25a) in the first hydrogen discharge line (4).

10. The system according to any one of claims 8 and 9, wherein the heat pump comprises a second evaporator (25b).

11. The system according to claim 10, as referenced to claim 4 or 5, wherein the second evaporator (25b) is arranged in series downstream of the first heat exchanger (9) in the fluid circuit (27) of the heat pump.

12. The system according to claim 11, further comprising at least one third heat exchanger (19) located downstream of the second evaporator (25b) in the first hydrogen discharge line (4).

13. The system according to any one of claims 10 to 12, further comprising a liquid / gas separator (17) downstream of the second heat exchanger (16) and upstream of the second evaporator (25b).

14. The system according to any one of claims 9 to 13, as referenced from claim 6 or 7, wherein the second heat exchanger (16) is located between the first hydrogen discharge line (4) downstream of the first evaporator (25a) and the second air supply line (10).

15. The system according to any one of claims 12 to 14, further comprising a compressor (12) located in the second air supply line (10) and intended to compress air.

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