Light-water-reactor (LWR) nuclear cogeneration plant and high-temperature water electrolysis system(s) for producing hydrogen using heat from the lwr

Abstract

The subject matter of the invention is essentially that of obtaining an indirect optimal thermal coupling between a nuclear reactor and a production unit for producing hydrogen by high-temperature electrolysis by means of a suitably chosen draw-off tap downstream of the high-pressure body of the Rankine cycle turbine of the nuclear reactor, which will transfer the heat thus drawn off by means of a closed loop between an intermediate heat exchanger and a coupling steam generator to liquid water supplied to the production unit in order to inject steam at a high temperature required to perform the electrolysis. This indirect heat input may be carried out continuously or at a decreasing rate until there is enough heat produced by the electrolysis reaction.

Description

[0001] Description

[0002] Title: Light Water Reactor (LWR) Nuclear Cogeneration Plant and High Temperature Water Electrolysis System(s) for Hydrogen Production from LWR Reactor Heat.

[0003] Technical field

[0004] The present invention relates to the field of light water nuclear reactors (LWR), in particular pressurized water reactors (PWR) or boiling water reactors (BWR). More particularly, the invention relates to cogeneration installations comprising such nuclear reactors. Unless otherwise stated, "cogeneration" is understood here and within the scope of the invention to mean the simultaneous or non-simultaneous production of electricity and, where appropriate, heat, and the production of hydrogen by electrolysis of water from the heat and electricity supplied by nuclear reactors.

[0005] The main objective of the invention is to optimize the efficiency of the primarily thermal coupling in order to optimize the production of hydrogen from the heat supplied by nuclear reactors.

[0006] The production of hydrogen within the framework of the invention is carried out by high temperature water electrolysis (EHT, or EVHT for high temperature water vapor electrolysis, or HTE English acronym for "High Temperature Electrolysis", or HTSE English acronym for "High Temperature Steam Electrolysis") also with solid oxides (SOEC, English acronym for "Solid Oxide Electrolysis Cell").

[0007] Although described with reference to a pressurized water nuclear reactor, the invention applies to any nuclear reactor with an indirect thermodynamic cycle of the family of so-called second, third, fourth generation (GEN IV) reactors. It applies in particular to boiling water nuclear reactors (BWR), with fast neutrons cooled with liquid metal, in particular liquid sodium called RNR-Na or SFR (English acronym for "Sodium Fast Reactor") and which is part of the family of GEN IV reactors.

[0008] Prior art

[0009] In a context of climate and energy transition, the nuclear industry must address several challenges for the future. Indeed, to meet the energy and societal challenges of tomorrow, it will be appropriate to design nuclear reactors that allow: - to limit the need for so-called "environmental" liquid cold sources (rivers, streams, sea) and the associated discharges into the environment;

[0010] - to be more flexible and therefore more complementary to other so-called renewable energies (RE), to meet the fluctuating demand for electricity and the intermittency of RE;

[0011] - to decarbonize processes by providing heat to consuming industries (desalination, heat networks, hydrogen, etc.) while increasing energy efficiency;

[0012] - to capture atmospheric CO2 to limit the effects of global warming and contribute to closing the carbon cycle as a source of carbon for industrial processes; and this, without degrading the profitability of the installation, either by benefiting economically from the new services provided, or by significantly increasing the quantity of electricity produced during the day.

[0013] A pressurized water nuclear reactor (PWR) typically comprises three cycles (fluid circuits), the general principle of normal operation of which is explained below with reference to Figure 1. The temperatures and efficiency are given for illustrative purposes.

[0014] The primary circuit 1 is a closed-loop fluid circuit mainly comprising the core of the reactor 2, at least one steam generator (SSG), as an exchanger called primary exchanger 3 and a hydraulic pump 4 for circulating the heat transfer fluid which is water maintained in the liquid state in the operating temperature range of the reactor, typically around 320°C-330°C in normal operation. Other equipment, such as a pressurizer and all the devices for ensuring operation under the required safety conditions, are not described here.

[0015] Thus, the high-pressure water in the primary circuit extracts the energy supplied, in the form of heat, by the fission of uranium nuclei in the core of reactor 1.

[0016] Then, this water under high pressure and high temperature, typically 155 bars and 320°C- 330°C, enters the intermediate exchanger 3 and transmits its energy to a secondary circuit 5, also using pressurized water as a heat transfer fluid in a closed loop.

[0017] This secondary circuit 5 comprises the intermediate exchanger 3, a turbine 6 comprising a high-pressure body 60 and a low-pressure body 61, a condenser 7 and a hydraulic pump 8 for circulating the water in the form of steam as a heat transfer fluid. Thus, in this secondary circuit 5, the water in the form of steam, at high pressure, typically at approximately 70 bars, is expanded in the high-pressure body of the turbine, then superheated before continuing its expansion in the low-pressure bodies 61. The turbine drives an alternator 9 which produces electricity.

[0018] The water from the secondary circuit is then condensed via the condenser 7 in a third cycle, the cooling cycle 10, as a so-called "cold" source. This cycle 10 mainly comprises humid air cooling towers 11, which are hollow towers in their center in which a current of air is naturally created, entering at the bottom and leaving at the top. In passing, this current of air takes the heat contained in the water from the cooling circuit and disperses it into the atmosphere in the form of a cloud of water vapor. The operation is reproduced continuously in which the water is distributed into fine droplets, which allows on the one hand a good exchange between the water and the air and therefore brings the water to a temperature close to that of the ambient air and on the other hand saturates with water vapor the air flow circulating from bottom to top in the tower.Part of the water flow evaporates in tower 11, the rest falls as rain in the basin located below the tower where it is pumped and returns to cool condenser 7. The evaporated water is replaced by tertiary water called "environmental" pumped upstream from a river, a stream or a sea. This significantly increases the temperature of these watercourses, which in hot periods and / or when the flow of these watercourses is low can lead a nuclear facility operator to reduce their power level or even shut them down.

[0019] As shown in Figure 1, as an example, the thermodynamic efficiency of a PWR is of the order of 33 to 34%, the water temperature at the inlet of the condenser 7 is of the order of 20°C and 35°C at its outlet.

[0020] In the classic REP sector, reactors are classified by major families of use:

[0021] - so-called electrogenic reactors which are dedicated solely to the production of electricity;

[0022] - so-called calogenic reactors which are dedicated solely to the production of heat;

[0023] - so-called cogeneration reactors, dedicated to both the production of electricity and heat or to the production of electricity and, where appropriate, heat and hydrogen, simultaneously or not. As detailed in [1], one principle of cogeneration of electricity and heat from a nuclear reactor consists of modifying the design of the energy conversion cycle so that the heat is released at the cold source at a temperature that allows recovery. This principle is rather applied for an installation, such as one intended for seawater desalination or district heating, where the heat required is at a relatively low temperature, typically around 150°C.

[0024] Limiting global warming requires minimizing heat loss at all levels, particularly at the cold source of a thermodynamic installation. This cogeneration objective becomes all the more relevant for a nuclear reactor since industrial or domestic heat is often traditionally obtained by burning fossil fuels responsible for greenhouse gas emissions.

[0025] To achieve this objective, a first configuration consists of modifying the components of the electrical production system of a REP installation in order to adjust the water temperature at the cold source.

[0026] In a conventional configuration, illustrated in Figure 1, this modification remains limited, however. It does not affect the high-pressure turbine 60 but only the low-pressure turbine 61 ensuring the Rankine cycle. This modification illustrated in Figure 2 consists of bringing the operating point P of the low-pressure turbine 61 to a pressure of the order of one bar, instead of approximately 50 mbar, so that the water leaving the condenser has a sufficiently high temperature level, typically 70°C, to be used, for example in a heat network 12. This modification is accompanied first of all by a reduction in the electrical power produced, since the thermodynamic efficiency drops to 27%. There is also an increase in the pressure in the condenser 7.

[0027] Recently, many studies have highlighted the possibility of combining nuclear power reactors with hydrogen production units based on high-temperature water electrolysis, in order to create cogeneration plants that can efficiently produce electricity and hydrogen: [2], [3].

[0028] Water electrolysis is an electrochemical reaction that decomposes water into oxygen and hydrogen gas with the help of an electric current according to the reaction: To carry out the electrolysis of water, it is advantageous to carry it out at a high temperature, typically between 600 and 950°C, because part of the energy required for the reaction can be provided by heat, which is cheaper than electricity, and carrying out the reaction is more efficient at high temperatures, and finally it may not require a catalyst.

[0029] To implement high-temperature electrolysis, it is known to use a reactor, also called a SOEC type electrolyzer (acronym for "Solid Oxide Electrolysis Cell"), consisting of a stack of elementary patterns each comprising a solid oxide electrolysis cell, consisting of three anode / electrolyte / cathode layers superimposed on each other, and interconnection plates, for example made of metal alloys, also called bipolar plates, or interconnectors. The interconnectors have the function of ensuring both the passage of the electric current and the circulation of gases in the vicinity of each cell (injected water vapor, hydrogen and oxygen extracted in an EHT electrolyzer) and of separating the anode and cathode compartments which are the gas circulation compartments on the side of the anodes and cathodes of the cells respectively.To perform high-temperature water vapor electrolysis (HTE), water vapor (H2O) is injected into the cathode compartment. Under the effect of the current applied to the cell, the dissociation of water molecules in vapor form occurs at the interface between the hydrogen electrode (cathode) and the electrolyte: this dissociation produces dihydrogen gas (H2) and hydroxide ions (OH'). The dihydrogen is collected and discharged at the outlet of the hydrogen compartment. The hydroxide ions (OH') migrate through the electrolyte and recombine into dioxygen at the interface between the electrolyte and the oxygen electrode (anode).

[0030] To increase the flow rates of hydrogen and oxygen produced, it is known to stack several elementary electrolysis cells on top of each other, separating them by interconnection devices, usually called interconnectors or bipolar interconnection plates. The assembly is positioned between two end interconnection plates which support the electrical and gas supplies of the electrolyser (electrolysis reactor).

[0031] A high-temperature water electrolyser (HTE) thus comprises at least one, generally a plurality of electrolysis cells stacked on top of each other, each elementary cell being formed of an electrolyte, a cathode and an anode, the electrolyte being interposed between the anode and the cathode. In permanent operating mode, a high-temperature electrolyser HTE needs upstream a combined input of thermal and electrical power to bring the reactants to the temperature necessary for electrolysis and within it an input of electrical power to carry out the electrolysis.

[0032] In order to ensure the supply of heat and electricity to an EHT electrolyser, patent CN207603212 proposes a configuration for drawing high-temperature, high-pressure steam from the steam generator (SG) of a nuclear reactor to be injected directly into the EHT electrolyser. This configuration has many major drawbacks:

[0033] - at the reactor safety level: by taking steam from the GV outlet to supply the EHT electrolyser, the water inventory of the secondary circuit is impacted. This configuration requires the installation of a water supply and treatment unit with the physicochemical properties required by the secondary circuit to permanently maintain the water inventory of this circuit. In addition, any failure in this unit can lead to a partial or total loss of the steam generator power evacuation function on the primary circuit and therefore have consequences on the safety of the overall installation;

[0034] - at the level of the operation of the overall installation: having water that feeds both the secondary circuit and the EHT electrolyser requires compatibility between the physicochemical requirements of the secondary water and the electrolyser feed water. As a preliminary, for example, the requirements of non-aggressiveness of the secondary water on the materials of the secondary loop require treatments by adding chemical products, which appear to be difficult to reconcile with water intended to feed an electrolyser. Indeed, the water introduced into an EHT electrolyser must be as pure as possible because the impurities remain within the electrolyser and accumulate over time.These impurities can in fact end up disrupting the electrolytic reactions on the one hand by the formation of sludge and on the other hand, by the action of chlorides (halides in general) which destroy the protection by nickel plating or the solid nickel generally required for the anodes of an EHT electrolyser.

[0035] - at the level of the safety of the overall installation, due to the transport of pressurized steam from the conventional island of the nuclear installation (engine room) to the EHT electrolysis unit, leads to a compatibility constraint between the capacity to separate the installation from the unit and the risk analysis imposing a minimum distance between them: we can refer to publication [4] which indicates a safety distance estimated at 1 km which must be able to be reduced taking into account the risk analysis carried out.

[0036] Publication [3] proposes a coupling configuration between a nuclear installation of the REP type for Rankine cycle power generation and an EHT electrolyser unit. In the proposed coupling configuration, the heat extraction to supply an EHT electrolyser is carried out indirectly, i.e. without direct extraction of water vapor. This avoids impacting the water inventory of the secondary circuit. This coupling configuration thus proposes the installation of a fluid loop extracting steam directly from the steam generator outlet, i.e. at approximately 280°C, and reinjecting the steam after passing through an exchanger, directly at the condenser of the Rankine cycle. In this configuration, the extracted heat is not fully used by the proposed EHT unit, which is not efficient from a thermal point of view.

[0037] In summary, the energy efficiency of nuclear cogeneration installations as mentioned above is not optimal, because the coupling between the nuclear reactor(s) for electrogenic and / or calogenic purposes and the EHT electrolyser unit for hydrogen production is not optimal.

[0038] However, this energy efficiency plays a key role in the economic relevance of producing decarbonized hydrogen. Designing efficient and safe nuclear cogeneration facilities will help ensure the feasibility of deploying such a sector.

[0039] There is therefore a need to improve nuclear cogeneration installations, i.e. the simultaneous or non-simultaneous production of electricity and hydrogen from the heat supplied by the nuclear reactor(s) of the installation, by optimizing the thermal coupling between the nuclear reactor(s) and the high-temperature electrolysis (HTE) unit dedicated to the production of hydrogen, in particular:

[0040] - with a yield at least equal to the solutions proposed until now,

[0041] - which does not disrupt the safety of the nuclear reactor(s),

[0042] - which does not present a risk to the overall safety of the installation, without complicating the operating conditions of both the nuclear reactor(s) and the EHT unit considered separately.

[0043] The aim of the invention is to meet this need at least partially.

[0044] Statement of the invention

[0045] To this end, the invention relates, in one of its aspects, to an electronuclear cogeneration installation, intended to produce electricity and, where appropriate, heat, and hydrogen, comprising:

[0046] - at least one nuclear reactor, in particular pressurized water reactor (PWR) or boiling water reactor (BWR), comprising:

[0047] • a first fluid circuit, called the primary circuit, comprising at least a first steam generator as a first intermediate heat exchanger;

[0048] • a second fluid circuit, called the secondary circuit, comprising: at least one turbine comprising a high-pressure body connected to the first steam generator and a low-pressure body connected to the high-pressure body by at least one fluid branch, a high-pressure heater connected in a closed loop to the high-pressure body, to a water tank, called the feed tank, and to the first steam generator, a low-pressure heater connected on the one hand by at least one fluid branch to the low-pressure body and on the other hand by at least one fluid branch to the feed tank, a condenser connected on the one hand to the low-pressure body and on the other hand in a closed loop to the low-pressure heater; an alternator mechanically coupled to the turbine, intended to be connected to an electrical network.

[0049] According to the invention, the installation comprises at least one high-temperature electrolysis unit EHT thermally coupled to the nuclear reactor by a third fluid circuit, called the injection coupling circuit, comprising: a second intermediate heat exchanger connected in a closed loop to a draw-off tapping, made in the fluid branch between the high-pressure body and the low-pressure body of the turbine, and to the feed tank, a second steam generator, called the coupling steam generator, connected on the one hand in a closed loop to the second heat exchanger, and on the other hand to a fluid branch whose inlet is connected to a liquid water supply, separate from the primary and secondary circuits of the nuclear reactor and the outlet is connected to the inlet of the high-temperature electrolysis unit so as to inject therein the water vapor produced by the coupling steam generator.

[0050] Advantageously, the liquid water supplying the coupling steam generator is demineralized water.

[0051] By "high temperature water electrolysis unit" is meant here and within the scope of the invention a hydrogen production unit comprising one or more high temperature water electrolysers (HTE) in series or in fluid parallel, each electrolyser comprising at least one, generally a plurality of electrolysis cells stacked on top of each other, each elementary cell being formed of an electrolyte, a cathode and an anode, the electrolyte being interposed between the anode and the cathode. The electrolysis unit further comprises all the components upstream and downstream of the electrolyser(s), for example the heat exchangers, the compressors of hydrogen and oxygen produced. . . Reference may be made to figures 2 and 3 of the publication [5].

[0052] According to an advantageous configuration, the nuclear reactor is a PWR reactor comprising a steam dryer, arranged on the fluid branch connecting the high pressure body and the pressure body of the turbine, the withdrawal tapping being made at a point on the branch between the high pressure body and the steam dryer.

[0053] Advantageously, the injection coupling circuit is adapted to take steam from the withdrawal tapping at a temperature at most equal to 200°C, advantageously still between 150 and 180°C, so that the coupling steam generator transforms the liquid water which feeds it into steam at a temperature at most equal to 40°C, advantageously between 10 and 35°C.

[0054] Preferably, the heat transfer fluid of the closed loop connecting the coupling steam generator to the second heat exchanger is pressurized water.

[0055] According to an advantageous embodiment, the high-temperature electrolysis production unit EHT is further thermally coupled to the nuclear reactor by a fourth fluid circuit, called the reinjection coupling circuit, comprising: a fourth intermediate heat exchanger connected in a closed loop to a first reinjection tapping made between the low-pressure heater and the feed tank, and to a second reinjection tapping made between the condenser and the low-pressure heater, a fifth intermediate heat exchanger, called the coupling exchanger, connected on the one hand to a fluid branch whose inlet is connected to a liquid water supply coming from the high-temperature electrolysis unit and the outlet is connected to at least one cooling circuit of the high-temperature electrolysis unit and on the other hand in a closed loop to the fourth heat exchanger,so as to evacuate at least part of the excess heat from the high-temperature electrolysis unit and reinject it into the secondary circuit of the nuclear reactor.,

[0056] According to this mode, the reinjection coupling circuit is preferably adapted to take liquid water from the high-temperature electrolysis unit at a temperature at least equal to 80°C, advantageously between 85 and 95°C.

[0057] Preferably, the heat transfer fluid of the closed loop connecting the coupling exchanger to the fourth heat exchanger is pressurized water.

[0058] Advantageously, the alternator is adapted to supply at least part of its electricity to the high-temperature electrolysis unit.

[0059] According to an advantageous embodiment, the draw-off connection is provided with a valve for regulating the inlet pressure in the third intermediate exchanger. Preferably, the regulating valve is also a valve for regulating the inlet pressure in the high-pressure heater.

[0060] Advantageously, the second intermediate heat exchanger is of identical structure to that of the high pressure heater.

[0061] The invention essentially consists in achieving an optimal indirect thermal coupling between a nuclear reactor and a hydrogen production unit by high-temperature electrolysis via a judiciously chosen withdrawal tapping downstream of the high-pressure body of the turbine of the Rankine cycle of the nuclear reactor which will transfer the heat thus withdrawn, via a closed loop between an intermediate heat exchanger and a coupling steam generator, to liquid water supplying the production unit in order to inject steam at a high temperature required to carry out the electrolysis. This indirect heat supply can be carried out continuously or decreasingly until the heat released by the electrolysis reaction is sufficient to supply it by itself.

[0062] By "indirect" is meant here and within the framework of the invention the fact that there is no mass transfer between the cycles of the nuclear reactor and the EHT electrolysis hydrogen production unit, and therefore that the heat transfer takes place through heat exchangers.

[0063] According to an advantageous embodiment, another closed loop with a heat exchanger is also used to achieve indirect coupling by return of the fatal heat from the EHT electrolysis hydrogen production unit to the nuclear reactor. In other words, according to this embodiment, the thermal discharges from the EHT electrolysis hydrogen production unit are at least partly reinjected into the nuclear reactor.

[0064] Ultimately, the indirect thermal coupling proposed to bring the heat from a reactor to a high-temperature electrolysis unit, and advantageously with an indirect coupling by reinjection of the fatal heat from the electrolysis unit, presents a number of advantages, among which we can cite:

[0065] - an overall efficiency of the nuclear cogeneration installation at least equal to existing solutions,

[0066] - unmodified nuclear reactor safety,

[0067] - the absence of risk for the overall installation,

[0068] - operating conditions of the nuclear reactor and the EHT unit which remain the same and independent of each other.

[0069] Other advantages and characteristics of the invention will become more apparent upon reading the detailed description of examples of implementation of the invention given by way of illustration and not limitation with reference to the following figures.

[0070] Brief description of the drawings

[0071] [Fig 1] Figure 1 schematically illustrates a configuration of a pressurized water reactor (PWR) operating solely as a power reactor according to the state of the art. [Fig 2] Figure 2 is a schematic view of a configuration of a pressurized water reactor (PWR) modified to operate as a cogeneration reactor according to the state of the art.

[0072] [Fig 3] Figure 3 is a schematic view showing in more detail the components of the secondary and tertiary circuits of a state-of-the-art pressurized water reactor (PWR) nuclear power plant.

[0073] [Fig 4] Figure 4 is a schematic view of a cogeneration installation of a pressurized water reactor (PWR) thermally coupled with a high temperature electrolysis unit according to the invention.

[0074] Detailed description

[0075] Throughout the present application, the terms "upstream" and "downstream" are to be understood with reference to the direction of circulation of a heat transfer fluid within one of the fluid circuits of a nuclear cogeneration installation according to the invention.

[0076] Points A to H of the different fluid lines concerned in Figure 4 are symbolized by black dots.

[0077] Figures 1 and 2 relating to the state of the art have already been detailed in the preamble, they will therefore not be commented on below.

[0078] For the sake of clarity, the same element according to the invention and according to the state of the art is designated by the same numerical reference in all of Figures 1 to 4.

[0079] A nuclear installation with a PWR reactor as currently existing is shown.

[0080] The primary circuit 1 is a closed-loop fluid circuit mainly comprising the core of the reactor 2, an exchanger 3 as a steam generator (SPG), and a hydraulic pump 4 to circulate the heat transfer fluid which is water which passes from the liquid state to the vapor state, typically around 300°C at high pressure, typically around 70 bars, in normal operation.

[0081] Other equipment, such as a pressurizer and all the devices needed to ensure operation under the required safety conditions, are not described here.

[0082] The tertiary circuit 10 mainly comprises a turbine 6 consisting of a high pressure body 60 and a low pressure body 61 connected to the high pressure body 60 by a fluid branch 62, a condenser 7 connected to the low pressure body 61 by a fluid branch 63 and a hydraulic pump 80 for circulating the water in the form of steam as a heat transfer fluid.

[0083] Thus, in this circuit 10, the water in the form of steam is expanded in the high pressure body of the turbine, then superheated before continuing its expansion in the low pressure body 61. The turbine drives an alternator 9 which produces electricity.

[0084] The water from the secondary circuit is then condensed via condenser 7, as a so-called “cold” source.

[0085] The steam generator 3 produces steam for the high and low pressure bodies 60, 61 of the turbine 6, which is characteristic of a Rankine cycle with the operating conditions of an electric cycle of the installation and must be able to operate according to the needs of the electricity network.

[0086] The steam generator 3 is typically sized to evacuate 1.5 times the power of the nuclear reactor. It is specified that the bodies of the turbines 60, 61 are sized from the peak steam flow produced by the steam generator 30.

[0087] The hydraulic pump 4 is designed to operate at least at the availability coefficient Kd of the nuclear reactor and must be able to operate according to the fluctuations in the electricity requirements of the electrical network to which the alternator 9 of the nuclear reactor is electrically connected.

[0088] The flow rate of pump 4 must allow, taking into account the heat capacity of the heat transfer fluid and the sizing of steam generator 3, to supply it with heat transfer fluid at a flow rate allowing it to meet the power demands of the electrical network.

[0089] Pump 4 has metal walls resistant to chemical attacks from the heat transfer fluid at high temperatures, typically above 300°C. Several pumps can be positioned in parallel to distribute the pumping flow and for safety reasons a redundant pump can be provided.

[0090] The circuit 10 also comprises a circuit for reheating the feed water of the steam generator 3 before it is injected / expanded in the form of steam into the pressure body 60 of the turbine 6. This reheating circuit firstly comprises a high-pressure heater 64 connected in a closed loop to the high-pressure body 60, to a water reservoir, called the feed tank 66, and to the first steam generator 30. It also comprises a low-pressure heater 65 connected on the one hand by at least one fluid branch to the low-pressure body and on the other hand by at least one fluid branch to the feed tank 66.

[0091] In this circuit, a pump 81 for extracting the condensate from the condenser 7 conveys it into the feed tank 66 via the low-pressure heater 65. The condensate is typically at a temperature of 40°C at a pressure of around 0.075 bars at the outlet of the condenser 7.

[0092] As shown in Figure 3, the low pressure heater 65 uses as a heat source the steam drawn from the low pressure body 61 of the turbine 6. The low pressure heater 65 thus heats the feed water of the steam generator 30. When the feed water leaves the low pressure heater 65, it has a temperature typically between 80 and 100°C.

[0093] The pump 80 makes it possible to bring this feed water from the feed tank 66 to the high-pressure heater 64 to bring it to a temperature of around 150°C at a pressure of 40 bars in the steam generator 30.

[0094] As shown in Figure 3, the high pressure heater 64 uses as a heat source the steam drawn from the high pressure body 60 of the turbine 6.

[0095] We do not detail again all the different relationships and functions of the common elements between a cogeneration installation with hydrogen production according to the invention and an installation with a PWR nuclear reactor according to the state of the art, as illustrated in Figure 3. Only the elements of the indirect thermal couplings according to the invention are described.

[0096] The nuclear cogeneration installation according to the invention illustrated in Figure 4 comprises, in addition to the usual components of a usual PWR reactor installation, which has just been described in relation to Figure 3, at least one high-temperature electrolysis unit EHT 100 thermally coupled to the nuclear reactor by an injection coupling circuit 200. This injection coupling circuit 200 firstly comprises an intermediate heat exchanger 202 connected in a closed loop to a withdrawal tapping A, made in the fluid branch 62 between the high-pressure body 60 and the low-pressure body 61 of the turbine, and to the feed tank 66. More precisely, taking into account the temperature and pressure of the hot steam that it is desired to withdraw, the withdrawal tapping A is at a point in the branch 62 which connects the high-pressure body 60 of the turbine and the dryer, not shown, of the PWR reactor.

[0097] As detailed below, this tapping at point A is chosen at the appropriate temperature level to provide the latent heat to vaporize the feed water of unit 100.

[0098] The draw-off branch A can be made in a strictly identical manner (type of weld, characteristic pipe diameter, etc.) to that of the draw-off supplying the high-pressure heater 64.

[0099] The tapping A is advantageously provided with a valve for regulating the inlet pressure in the intermediate exchanger 202. This regulating valve can also be a valve for regulating the inlet pressure in the high-pressure heater 64. This valve can thus be controlled in two different modes. This regulating valve makes it possible to optimize the operation and control of the coupling cycle 200, with great flexibility.

[0100] In the closed loop from the draw-off point A, the fluidic branch 201 allows the steam to be channeled and transferred to the exchanger 202. After heat exchange, the fluidic branch 203 returns the liquid water to a point B of the food tank.

[0101] This circuit also comprises a second steam generator, called a coupling steam generator 205, adapted to produce feed steam at an inlet point F of the electrolysis unit 100 from demineralized liquid water coming from a point E. This coupling generator 205 is also connected in an intermediate closed loop to the heat exchanger 202.

[0102] In this intermediate closed loop, a circulation pump 206 brings pressurized liquid water via the fluid branch 204 from the exchanger 202 to the coupling generator 205 and then, after heat exchange, returns the water via the fluid branch 207 to the exchanger 202. To further improve the thermal coupling between the PWR reactor and the EHT electrolysis unit, at least part of the fatal heat can be recovered, i.e. the heat emitted by the latter which was not used for the electrolysis reaction.

[0103] To do this, the installation includes a coupling circuit 300 by reinjection of heat into the tertiary circuit 10 of the reactor.

[0104] This circuit 300 firstly comprises an intermediate heat exchanger 302 connected in a closed loop to a first reinjection tapping made at point C between the low pressure heater 65 and the food tank 66, and to a second reinjection tapping made at point D between the condenser 7 and the low pressure heater 65.

[0105] In this closed loop from the withdrawal point D, the fluidic branch 303 brings pressurized liquid water to the exchanger 302 and after exchange, the fluidic branch 301 makes it possible to channel and transfer the pressurized liquid water to point C, which makes it possible to reinject at least part of the excess calories from the EHT 100 unit into the Rankine conversion cycle 10 of the reactor.

[0106] This circuit also comprises an intermediate heat exchanger 305, called a coupling exchanger, connected on the one hand to a fluid branch 308 whose inlet at the draw-off point G is connected to a supply of liquid water coming from the EHT unit 100 and the outlet is connected to at least one cooling circuit of the EHT unit 100.

[0107] This coupling exchanger 305 is connected in an intermediate closed loop to the heat exchanger 302, so as to evacuate at least part of the surplus heat from the high-temperature electrolysis unit and reinject it into the tertiary circuit of the nuclear reactor.

[0108] The liquid water coming from the EHT 100 unit is at a temperature at least equal to 80°C, advantageously between 85 and 95°C.

[0109] In this intermediate closed loop, a circulation pump 306 brings pressurized liquid water via the fluid branch 304 from the coupling exchanger 305 to the exchanger 302 and then, after heat exchange, returns the water via the fluid branch 307 to the exchanger 202.

[0110] In the illustrated example, all of the fluid branches 201, 203, 204, 207, 208 of the circuit 200 and the fluid branches 301, 303, 304, 307, 308 of the circuit 300, each consisting of a pipe of cylindrical section, preferably with metal walls, is insulated from the outside with a high-temperature insulator. The diameter of a pipe is calculated to allow all of the thermal power to be evacuated with a maximum permissible flow rate of the heat transfer fluid, typically of the order of 1 to 10 m / s.

[0111] The electrical network connected to alternator 9 aims to transport and distribute electricity to end users according to their needs. It is a high-voltage electrical network operating according to the power demands linked to electricity uses, which must be able to accept the peak electrical power produced by the cogeneration installation.

[0112] In addition, the alternator 9 can supply the electricity needs of the EHT unit 100, including the electrolysers which require direct current, to implement high temperature electrolysis.

[0113] The inventors carried out a dimensioning of all the components of the cogeneration installation, with the characterization of each point of the circuits 200, 300 in temperature and pressure. This dimensioning is established from a software, used under the name CYCLOP, qualified by the applicant for dimensioning in permanent regime of thermodynamic conversion cycle.

[0114] The CYCLOP software essentially allows you to model an energy conversion cycle, consisting of different loops connected by thermal, mechanical or electrical exchanges. Each loop is made up of components (exchangers, pumps, turbines, etc.) connected to each other by a fluid circulation.

[0115] The operation of this software allows to calculate each thermodynamic point of the complete cycle and to deduce the production of useful energy and therefore its efficiency. Each component is characterized by selected macroscopic quantities, but it is possible to connect this tool to finer pre-dimensioning modules which allow to obtain finer characteristics of a given cycle.

[0116] The software also allows the efficiency of a cycle to be optimized based on its free parameters (turbine pressure ratio, withdrawal pressures and flow rates, etc.), using deterministic or genetic optimization algorithms. The use of this software and its relevance are described, for example, in [6] or [7]. Sizing can also be carried out using other commercial software, in particular that under the name THERMOFLEX®.

[0117] For the heat injection coupling circuit 200, a flow rate of approximately 300 kg / s was considered with a thermal coupling of a PWR reactor producing approximately 540 MWth and 180 MWe and considering hydrogen production by unit 100 of an equivalent electrical power.

[0118] From a practical point of view, assuming a flow velocity of 1.5 m / s in the fluidic branches 204, 207, 208, their pipe diameter can be about 500 mm with a resulting pressure drop of the order of 45 Pa / m considering only the regular pressure drops. For a diameter of 300 mm, a velocity of 4.25 m / s would be reached with a pressure drop of 850 Pa / m also considering only the regular pressure drops. It is also possible to envisage a number of three fluidic branches 204, 207, 208 of 300 mm in fluidic parallel, leading to a pressure drop of 45 Pa / m.

[0119] For the heat reinjection coupling circuit 300, a flow rate of approximately 100 kg / s was considered with thermal coupling of a PWR reactor producing approximately 540 MWth and 180 MWe and considering hydrogen production by unit 100 of equivalent electrical power.

[0120] From a practical point of view, assuming a flow velocity of 1.5 m / s in the fluidic branches, 304, 307, 308, their pipe diameter can be about 300 mm with a resulting pressure drop of the order of 45 Pa / m considering only the regular pressure drops.

[0121] The following Table 1 gives different values ​​of water temperature and pressure at the various points A to E mentioned above as well as in the various fluid branches concerned of circuits 200 and 300, which were obtained using the CYCLOP software. [Table 1]

[0122] The invention is not limited to the examples which have just been described; in particular, it is possible to combine characteristics of the illustrated examples within non-illustrated variants. Other variants and embodiments may be envisaged without departing from the scope of the invention.

[0123] In the example illustrated, the nuclear reactor is dedicated 100% to hydrogen production. The installation can be operated according to other choices with partial productions in nominal mode, for example a reactor power dedicated 50% to produce hydrogen and 50% to sell electricity to the network or in variable mode, for example a reactor power allowing to sell the electricity from the reactor when the market price is high and to produce hydrogen when the price is lower. The nuclear cogeneration installation which has just been described in relation to a pressurized water nuclear reactor can be implemented with all nuclear reactors with indirect thermodynamic cycle, for which the heat production cycle is physically separated from the energy conversion cycle, such as a boiling water reactor, or a 4th Generation nuclear reactor.

[0124] Thus, if the detailed example concerns a conventional pressurized water reactor, one can consider a cogeneration installation with a large or smaller reactor (SMR).

[0125] If the detailed example concerns a pressurized water reactor, the invention can just as well be applied to a boiling water reactor, the primary circuit 1 comprising the steam generator 3 as the first intermediate heat exchanger then being constituted by the boiling water reactor vessel from which the generated steam is directly sent into the high pressure turbine body 60, the water coming from the exchanger 64 then being injected as feed water for the reactor vessel.

[0126] List of cited references

[0127] [1]: “Improving energy efficiency by using cogeneration in electricity production” Jean-Marie Loiseaux, Henri Safa, Bernard Tamain, Save the Climate Network.

[0128] [2]: Fujiwara et al. “Hydrogen production by high temperature electrolysis with nuclear reactor”, Progress in Nuclear Energy 50 (2008).

[0129] [3]: Richard D. Boardman et al. “Developing a low-cost renewable supply of hydrogen with high-temperature electrochemistry”, MRS Bulletin, volume 47, March 2022, mrs.org / bulletin.

[0130] [4]: Austin Glover et al. “Assessment of hydrogen plant risks for sitting near nuclear power plants”, PSAM 16, June 26-July 1, 2022.

[0131] [5]: “Dynamic performance analysis of a high-temperature steam electrolysis plant integrated within nuclear-renewable hybrid energy systems”. Applied Energy Volume 228, 15 October 2018, Pages 2090-2110. https: / / doi.Org / 10.1016 / j.apenergy.2018.07.060.

[0132] [6]: H.D. Nguyen, N. Alpy, D. Haubensack. “Insight on electrical and thermal powers mix with a Gen2 PWR: Rankine cycle performances under low to high temperature grade cogeneration.” Energy, Elsevier, 2020, 202, pp.117518. ffl0.1016 / j. energy.2020.117518ff. ffcea-02569231f.

[0133] [7]: D. Haubensack et al., “The COPERNIC / CYCLOP computer tool: pre-conceptual design of generation 4 nuclear systems, HTR-2004” , 2nd International Topic Conference for the HTGR, September 22-24, 2004, Beijing, China, 2004.

Claims

Claims 1. Nuclear cogeneration installation, intended to produce electricity and, where appropriate, heat, and hydrogen, comprising: - at least one nuclear reactor, in particular pressurized water reactor (PWR) or boiling water reactor (BWR), comprising: • a first fluid circuit, called primary circuit (1), comprising at least one first steam generator (3) as a first intermediate heat exchanger; • a second fluid circuit, called secondary circuit (10) comprising: at least one turbine (6, 60) comprising a high pressure body (60) connected to the first steam generator and a low pressure body (61) connected to the high pressure body by at least one fluid branch (62), a high pressure heater (64) connected in a closed loop to the high pressure body (60), to a water tank, called feed tank (66), and to the first steam generator (30), a low pressure heater (65) connected on the one hand by at least one fluid branch to the low pressure body (61) and on the other hand by at least one fluid branch to the feed tank, a condenser (7) connected on the one hand to the low pressure body and on the other hand in a closed loop to the low pressure heater; an alternator (9) mechanically coupled to the turbine, intended to be connected to an electrical network; - at least one high temperature electrolysis unit EHT (100) thermally coupled to the nuclear reactor by a third fluidic circuit, called injection coupling circuit, comprising: a second intermediate heat exchanger connected in a closed loop to a draw-off tapping, made in the fluidic branch between the high pressure body and the low pressure body of the turbine, and to the feed tank, a second steam generator, called coupling steam generator as a third heat exchanger, connected on the one hand in a closed loop to the second heat exchanger, and on the other hand to a fluidic branch (208) whose inlet is connected to a liquid water supply, separate from the primary and secondary circuits of the nuclear reactor and the outlet is connected to the inlet of the high-temperature electrolysis unit so as to inject the water vapor produced by the coupling steam generator.

2. Cogeneration installation according to claim 1, the nuclear reactor being a PWR reactor comprising a steam dryer, arranged on the fluid branch (62) connecting the high pressure body and the pressure body of the turbine, the withdrawal tapping (A) being made at a point on the branch (62) between the high pressure body (60) and the steam dryer.

3. Cogeneration installation according to one of claims 1 or 2, the injection coupling circuit being adapted to take steam from the withdrawal tapping at a temperature at most equal to 200°C, advantageously between 150 and 180°C so that the coupling steam generator transforms the liquid water which feeds it into steam at a temperature at most equal to 40°C, advantageously between 10 and 35°C.

4. Cogeneration installation according to one of the preceding claims, the heat transfer fluid of the closed loop connecting the coupling steam generator to the second heat exchanger being pressurized water.

5. Cogeneration installation according to one of the preceding claims, the high-temperature electrolysis production unit EHT (100) being further thermally coupled to the nuclear reactor by a fourth fluid circuit, called the reinjection coupling circuit, comprising: a fourth intermediate heat exchanger connected in a closed loop to a first reinjection tapping made between the low-pressure heater and the feed tank, and to a second reinjection tapping made between the condenser and the low-pressure heater, a fifth intermediate heat exchanger, called the coupling exchanger, connected on the one hand to a fluid branch (308) whose inlet is connected to a liquid water supply coming from the high-temperature electrolysis unit and the outlet is connected to at least one cooling circuit of the high-temperature electrolysis unit and on the other hand in a closed loop to the fourth heat exchanger,so as to evacuate at least part of the excess heat from the high-temperature electrolysis unit and reinject it into the secondary circuit of the nuclear reactor., 6. Cogeneration installation according to claim 5, the reinjection coupling circuit being adapted to take liquid water from the high-temperature electrolysis unit at a temperature at least equal to 80°C, advantageously between 85 and 95°C.

7. Cogeneration installation according to one of claims 5 or 6, the heat transfer fluid of the closed loop connecting the coupling exchanger to the fourth heat exchanger being pressurized water.

8. Cogeneration installation according to one of the preceding claims, the alternator being adapted to supply at least part of its electricity to the high-temperature electrolysis unit (100).

9. Cogeneration installation according to one of the preceding claims, the withdrawal tapping being provided with a valve for regulating the inlet pressure in the third intermediate exchanger.

10. Cogeneration installation according to claim 9, the control valve further being a control valve for the inlet pressure in the high pressure heater.

11. Cogeneration installation according to one of the preceding claims, the second intermediate heat exchanger being of identical structure to that of the high pressure heater.

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