Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21D—NUCLEAR POWER PLANT
  • G21D1/00—Details of nuclear power plant
  • G21D1/02—Arrangements of auxiliary equipment
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21D—NUCLEAR POWER PLANT
  • G21D3/00—Control of nuclear power plant
  • G21D3/04—Safety arrangements
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin

Definitions

• the invention relates to a device for emergency power supply of auxiliary components of a nuclear power station and in particular of a power station comprising a nuclear reactor cooled by pressurized water and a method for producing an emergency power supply, in the event of a failure of the main power supply to the auxiliary components of the nuclear power plant.
• auxiliary components of a nuclear power plant used in particular for monitoring, controlling or backing up main components of the power plant must be permanently supplied with electric current in order to be able to perform their functions during all the operating phases of the nuclear power reactor. the power plant.
• equipment such as circuit breakers and contactors, reversing contactors for motorized valves and solenoid valves installed in the electrical rooms of the nuclear power plant must be able to be permanently supplied, to be available in all circumstances, so as to ensure satisfactory operation of the nuclear reactor.
• batteries are usually used such as lead or cadmium batteries which can deliver, for example, a nominal voltage of 125 V with a maximum current of 250 A.
• the batteries do not output any current except in the case of occasional peaks in current consumption resulting from the supply of a large number of components.
• the batteries In the event of an interruption to the normal power supply to the power plant, the batteries must alone ensure the supply of energy to the electrical equipment, such an incident or accident which may, for example, be a local failure of the equipment supply means electric. In this case, the batteries must be able to supply electrical equipment for at least one hour without the voltage at the battery terminals falling below a limit voltage of around 105 V, the nominal voltage being 125 V .
• the size and mass of the batteries capable of performing this function are extremely important, in order to achieve the desired minimum autonomy of the power supply.
• Nuclear reactors cooled by pressurized water have a primary circuit in which pressurized water is circulated by primary pumps comprising a pump impeller which is rotated inside the volute of the pump by a shaft connected to the pump motor.
• the shaft of the primary pump crosses several series of seals between its part connected to the motor, at atmospheric pressure, and its end part connected to the pump wheel, inside the volute receiving l water under very high pressure and at very high temperature.
• a high-power charge pump supplies the joints with cold water.
• the injection of water into the first series of pump seals is ensured by a positive displacement pump driven by an electric motor which is generally supplied with three-phase 380 V alternating current.
• a backup power supply for the water injection pump motor must be provided in the primary pump seals. It has been proposed, for example, to use turbo-alternators supplied by the steam generators of the nuclear power station which are started in the event of an incident or accident resulting in an interruption of the supply of electric current to the injection pump.
• turbo-alternators The time required to start the turbo-alternators can cause an injection fault in the seals of the primary pump.
• turbo-alternators must be checked periodically and their maintenance can be costly.
• turbo-alternators for the production of driving current for the injection pump must be carried out within a maximum of two minutes after the loss of normal electrical supplies, which corresponds to the maximum operating time of the primary pump without supplying pressurized water to the seals. This period is defined to avoid any thermal shock on the alumina coating of the seals of the number 1 series of the primary pumps.
• turbo-alternators driven by steam drawn from steam generators can exhibit certain start-up failures, due in particular to the presence of water in the circuits.
• the object of the invention is therefore to propose a device for the emergency power supply of auxiliary components of a nuclear power plant which is compact, operates very safely and which has good autonomy, while requiring reduced maintenance operations.
• the emergency power supply device according to the invention comprises at least one fuel cell supplied with gas containing hydrogen and with gas containing oxygen from at least one reserve and at least one respective circuit of hydrogen-containing gas and oxygen-containing gas.
• an electrical supply device according to the invention and its use for the emergency supply of a water injection pump in the joints of a primary pump or an electrical monitoring and control panel.
• FIG. 1 is a diagram showing the installation of an emergency power supply device constituted by a fuel cell, in the circuits of a nuclear power plant comprising a pressurized water nuclear reactor.
• Figure 2 is a schematic view showing the theoretical constitution of a fuel cell using hydrogen as fuel.
• Figure 3 is a diagram showing the use of the emergency power supply device of Figure 1 for the supply of a water injection pump in the joints of a primary pump of the nuclear reactor and injection system auxiliaries in the primary pump seals.
• FIG. 4 is a detailed diagram of the electrical supply of an electrical supply panel for components of a nuclear power plant.
• FIG 1 there is shown schematically an emergency power supply device according to the invention, generally designated by the reference 1 and the tanks and circuits of the nuclear reactor used to operate the power device electric using a fuel cell.
• the device 1 mainly comprises several elements constituting fuel cells such as 2a and 2b placed in series and constituting several stages of production of electric current.
• the device 1 also comprises different circuits intended respectively to supply hydrogen and oxygen to all of the fuel cells, to cool the cells, to recycle hydro- gene not used and the elimination of water formed or introduced into all fuel cells.
• FIG 2 there is shown, schematically, a cell of a fuel cell of the PEMFC type using hydrogen as fuel and air as oxidant.
• the cell 3 shown in FIG. 2 is a unitary fuel cell cell intended to explain the operation of the fuel cell.
• the cell 3 comprises a hydrogen inlet compartment 3a, an air inlet compartment 3b and between the compartments 3a and 3b, the elements of the cell constituted by a first electrode 4a (anode), a second electrode 4b (cathode) and between the electrodes 4a and 4b, a membrane 6 of polymer material impregnated with water constituting a solid electrolyte.
• Catalyst 4'a (or 4'b) deposited on the porous electrode 4a (or 4b) lets the gases pass through the cell 3.
• the electrodes are produced by depositing on a conductive carbon fabric a mixture of platinum carbon powder.
• the anode 4a is supplied with hydrogen (or gas containing hydrogen) and the cathode 4b is supplied with gas containing oxygen, for example air.
• the fuel cell allows direct conversion into electrical energy, of the free energy of a chemical oxidation-reduction reaction using the hydrogen and oxygen introduced into the fuel cell.
• the hydrogen molecules Upon contact with anode 4a, the hydrogen molecules transform into hydrogen ions (protons) with the release of electrons.
• the hydrogen ions pass through the electrolyte as shown by the arrows 8 in FIG. 2, to reach the cathode 4b at the level of which the hydrogen ions and oxygen molecules are present. Under the effect of the catalyst contained in cathode 4b, the hydrogen ions ensure a reduction of the oxidizing oxygen of the air introduced into the fuel cell with absorption of electrons.
• the reaction produces water in the form of vapor, as shown by arrow 9.
• the electrons produced by the anodic reaction can circulate in a circuit of use 10 of the fuel cell, up to the cathode 4b. There is thus obtained a potential difference between the anode and the cathode and a current flow in the operating circuit 10 of the fuel cell.
• the theoretical potential of the fuel cell is 1.23 V, which corresponds to the redox potential of the O 2 / H 2 O couple.
• the membrane 6 is a membrane of cationic type, so that it lets through only the hydrogen ions H + coming from the anode 4a into which the molecular hydrogen H 2 is introduced (arrow 7'a). oxygen
• compartment 3 is introduced into the cathode 4b, as shown by the arrow 7'b.
• air introduced into compartment 3b passes through the entire fuel cell and entrains water vapor or water formed in the fuel cell, so that it is evacuated as well by the compartment 3a that by the compartment 3b of the fuel cell a mixture comprising water vapor or water formed in suspension in the sweeping air, as represented by the arrows 11 a and 11 b.
• bipolar plate 5a Between two successive cells is disposed a bipolar plate 5a attached to an anode and a respective cathode of the successive cells.
• the bipolar plates ensure the distribution of gases (hydrogen and oxygen) between the cells 3, the collection of electrons from one cell to the next and the evacuation of the products formed by the reactions in the fuel cell (in particular the water vapor), and the evacuation of the heat of reaction produced in the cell.
• Each of the unit cells comprises a bipolar plate, an anode, a membrane and a cathode, the second bipolar plate being common to two successive cells juxtaposed.
• a PEMFC cell of the usual type has a thickness of the order of 10 mm, so that, taking into account the dimensions of the end compartments, the entire fuel cell has a length of approximately 2300 mm. Units such as 2a and 2b shown in FIG. 1 are therefore juxtaposed in very large numbers, to constitute a fuel cell 2 having the electrical characteristics desired for ensuring the emergency power supply.
• the fuel cell is supplied with hydrogen and air, at the ends of each cell, at the level of a bipolar plate or of compartments 3a and 3b.
• the hydrogen supply to compartment 3a and the bipolar plates is ensured by means of a hydrogen circuit 12 connected to an inlet nozzle 13 of compartment 3a of the fuel cell and to the bipolar plates such as 5a.
• Nuclear power plants generally have their own hydrogen storage and distribution means which constitute a first part 12a of the hydrogen supply circuit 12 of the fuel cell.
• This part 12a of the circuit 12 comprises one or more hydrogen storage tanks 14 under high pressure (for example 197 bars), an expansion plate 15 of the hydrogen up to a distribution pressure (for example 7 bars) and a stop valve 15a for ensuring the distribution of hydrogen, for example in the volumetric and chemical control circuit of the nuclear reactor (arrow 16a) or in a circuit of use of the operator of the power station (arrow 16b).
• the circuit 12 for supplying the fuel cell 2 is for example produced by adding to the part 12a of the hydrogen circuit existing on the nuclear power plant a part of the circuit 12b comprising a second plate 17 for expansion of the hydrogen (by example up to 3 bars), a stop valve 17a, a non-return valve 17b, and a pipe 18 for joining the part 12a of the circuit downstream of the valve 15a to the nozzle 13 of the fuel cell. - corn.
• the hydrogen distribution circuit 12 further includes a recycling part 12c, ensuring the recovery of hydrogen not consumed in the fuel cell by means of a second nozzle 13 'of the first compartment 3a, the hydrogen recovered. being reintroduced into the pipe 18 connected to the nozzle 13 for entering the hydrogen in the first compartment 3a.
• the recovery circuit 12c comprises a separator 19 making it possible to separate the excess hydrogen from the water vapor formed in the fuel cell, the water vapor being condensed and then evacuated in a recovery circuit for the purges 20 of the reactor. nuclear.
• a non-return valve 21a On the hydrogen recovery circuit 12c, are also placed a non-return valve 21a, a stop valve 21b and a circulation pump 22 electrically supplied by the fuel cell.
• a hydrogen circuit specific to the fuel cell could be used.
• the air supply to the second compartment 3b of the fuel cell and the bipolar plates supplying the oxidizing oxygen and ensuring the scanning of the fuel cell is carried out by a circuit 24 connected to a nozzle 23 of the second compartment 3b by a pipe 25.
• the circuit 24 comprises a reservoir 26 of compressed air which is a usual component used in a nuclear power plant.
• a buffer tank 26 of compressed air with a capacity of 4 m 3 is used , allowing the supply of air to the cell under a pressure of 3 bars.
• an expansion plate for the compressed air 27 (for example up to a pressure of 3 bars) and a stop valve 27a.
• the use of oxygen improves the efficiency of the fuel cell.
• a circuit 28 connected to a nozzle 23 'opening into the second compartment 3b of the fuel cell makes it possible to evacuate the water vapor formed in the fuel cell in mixture with air blown into the fuel cell via circuit 24.
• Circuit 28 includes a separator 29 allowing the water formed in the purge recovery circuit 20 of the nuclear reactor to be removed.
• the air separated from the vapor is evacuated to the atmosphere by an exhaust pipe from the circuit 28.
• the fuel cell 2 heats up because part of the energy produced by the chemical reaction inside the fuel cell is released in the form of heat.
• demineralized water circuit 30 of the nuclear power plant It is necessary to cool the fuel cell and for this cooling water coming from a demineralized water circuit 30 of the nuclear power plant is injected into specific conduits of the fuel cell, by means of an injection circuit 31 comprising a pump 32, supplied with current by the fuel cell, for circulating demineralized water in circuit 31 and the fuel cell.
• Demineralized water could also flow under the effect of gravity from a tank at a level higher than that of the fuel cell.
• the water circulating in the fuel cell is recovered by a circuit 33 connected to the circuit 20 for recovering the purges of the nuclear reactor.
• the recovery circuit 33 includes branches connected to the anode parts and to the cathode parts of the fuel cell 2 by means of bipolar plates.
• a stop valve 33a is arranged on the circuit 33, to ensure, when it is opened, the evacuation of the recovered water, in the purge circuit 20.
• a fuel cell heater 44 (shown as a coil) keeps the fuel cell at operating temperature when the fuel cell is not used for backup power . This reduces the starting time of the fuel cell, when it becomes necessary to use it.
• a circuit for using the electric current produced by the fuel cell is designated by 10. The circuit is connected to the cathode and anode parts of the fuel cell by means of the bipolar plates, so that a direct current flows in the use circuit 10 at a constant voltage.
• the circuit for recovering the electric current produced under direct voltage by the fuel cell is connected, as shown in FIG. 3, to the components of the nuclear power plant for which continuity of the electrical supply is desired in the case of a incident or accident.
• the normal and emergency supply means of an electrical panel 40 and of components using electrical current have been shown such as solenoid valve coils, motors or contactors of the nuclear power plant or else fuel cell auxiliaries (e.g. pumps), via circuits 41.
• the normal supply means 42 of table 40 include in particular a supply unit connected to a supply network. alternating current of the nuclear power station and comprising a rectifier for obtaining direct current, for example at a voltage of 125 V.
• the emergency supply means comprise in particular the fuel cell 2 and an installation comprising at least one super-capacitor 38, the structural and functional characteristics of which will be described below.
• the fuel cell 2 and the installation of supercapacitors 38 are connected in parallel to the electrical panel 40 and to the general supply line connected to the circuits 41 and placed in series on the supply line, with respect to the normal supply. 42.
• On the connecting branches of the normal supply 42, of the fuel cell 2 and of the super-capacitors 38, to the general supply line are placed respective circuit breakers or relays 37, 39 and 43.
• the circuit breakers 37 and 43 When there is normal supply to the switchboard and user circuits, the circuit breakers 37 and 43 are closed and the circuit breaker 39 open.
• the table 40 and the user circuits 41 are supplied by the normal supply means 42.
• the super-capacitor (s) 38 are kept charged.
• the emergency power supply is put into service by opening the circuit breaker 37 and closing the circuit breaker 39.
• the panel 40 and the user circuits 41 are supplied first by the super-capacitors 38 then by the fuel cell 2 which is started up for the production of electric current, during the discharge of the super-capacitors 38. This thus ensures perfect continuity of the power supply.
• the super-capacitors are dimensioned to guarantee the supply of the panel 40 during the starting of the fuel cell.
• the interface between the super-capacitors 38 and a busbar of the power supply can be provided by a reversible chopper 38a which makes it possible to maintain a constant busbar voltage during the discharge of the super-capacitors.
• a DC or AC power supply can be produced at any voltage, for example 220V, 125V,
• the circuit 10 of a fuel cell 2 can also supply, via an inverter (or several inverters), one or more low voltage motors, for example supplied with 690 V or 380 V three phase.
• the circuit 10 can be used to ensure the continuity of the water supply to the seals of at least one primary pump of the nuclear reactor, by means of the positive displacement pump 35 rotation by the electric motor 35a, in the event of an interruption of the normal electric supply to the pump 35.
• the electric motor 35a for driving the pump 35 is supplied with three-phase alternating current at a voltage of 380 V, by means of a converter of the direct current supplied by the circuit 10 of the fuel cell into three-phase alternating current.
• the converter 36 consists of an inverter.
• super-capacitors placed in parallel with respect to the fuel cell make it possible to achieve a faster start-up of the injection pump in the event of loss of normal supply, during start-up and ramp-up. of the fuel cell.
• the emergency power supply to the auxiliary components 34 and 35 of the nuclear reactor can be ensured by the fuel cell as long as hydrogen fuel is available in the tanks of the nuclear power plant.
• the duration of use of a PE FC type fuel cell can be of the order of at least 10,000 hours. Therefore, the duration of continuous use of the emergency power supply device by fuel cell is limited only by the capacity of the hydrogen reserve.
• fuel cells can have high power densities, they are capable of providing adequate power. tation of switchboards and circuits for extended periods of time and completely independently.
• the total size of a fuel cell capable of supplying a switchboard and a set of user components is significantly smaller than the size of the batteries (in 220V, 125V, 48V or 30V) usually used, for one hour autonomy.
• a fuel cell as an emergency supply means relates to the supply of the water injection pump to the joints of a primary pump as described above.
• a fuel cell has the other advantage of not requiring any external energy source to start or operate and thus being completely autonomous.
• the starting up of the fuel cell is very rapid and the fuel cell only really works when it is necessary to supply electric current to supply the auxiliary components of the nuclear reactor, following a loss of 'power supply, which is advantageous in the case of all applications where the fuel cell is used as a backup source of electrical energy.
• the invention is not limited to the embodiment which has been described.
• an installation of super-capacitors placed in series or in parallel with the fuel cell Such an installation makes it possible to instantly supply the power necessary to the various user components, during the increase in power of the fuel cell.
• the super-capacitors also make it possible to supply power, in the presence of a consumption peak.
• the invention can therefore implement a hybrid system consisting of a fuel cell and one or more super-capacitors.
• super-capacitors capacitors which can provide by discharge much higher powers than conventional capacitors, with higher time constants.
• the super-capacitors which can be used in the case of the invention are based on the principle of the double-layer capacity.
• Supercapacitors are made up of two porous electrodes, an electrolyte and a porous separator.
• the production of capacitors can call on various technologies.
• the electrodes can be made of carbon, deposited polymers or hydrated metal oxides.
• the electrolyte used can be aqueous or of organic type.
• the super-capacitors used have the advantage of having excellent charge-discharge cyclability (> 100,000), a small footprint and requiring little maintenance.
• the super-capacitors must be accompanied by circuits ensuring a charge between the phases of use.
• fuel cell of the PEMFC type it is possible to use, in place of a fuel cell of the PEMFC type, other types of fuel cell, for example a fuel cell of one of the following types: alkaline cell (AFC) with or without membrane, cell phosphoric acid PAFC, MCFC molten carbonate cell, SOFC solid electrolyte cell, DMFC methanol cell.
• AFC alkaline cell
• PAFC cell phosphoric acid PAFC
• MCFC molten carbonate cell cell MCFC molten carbonate cell
• SOFC solid electrolyte cell SOFC solid electrolyte cell
• DMFC methanol cell any other electrical energy storage device such as batteries can be used, in place of super-capacitors, to provide instant power to users in the event of normal power loss.
• PEFMC type batteries which consume only hydrogen and air or pure oxygen are particularly well suited to be integrated into the circuits of a nuclear power plant.
• pure oxygen can be used from a dedicated reserve, or any other gaseous mixture containing oxygen at various contents.
• the invention however preferably uses a fuel cell which can be supplied directly with hydrogen or with oxygen-containing gas from the circuits of the nuclear power plant.
• the invention is not limited to the emergency supply of water injection pumps in the joints of the primary pumps of a pressurized water nuclear reactor but can be applied to compensate for any loss of electrical supply in a nuclear power station and to ensure a continuous electrical supply of auxiliary components of the power station comprising motors or pumps of small dimensions, circuit breakers, automaton relays or any other low voltage equipment supplied with direct current or alternating current.
• the power of installations powered by the hybrid system, fuel cell + super-capacitor can range up to 500 kVA.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Fuel Cell (AREA)
• Stand-By Power Supply Arrangements (AREA)

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Cited By (11)

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Citations (6)

• 2001
  • 2001-04-13 FR FR0105143A patent/FR2823592B1/fr not_active Expired - Lifetime
• 2002
  • 2002-04-09 CA CA002445185A patent/CA2445185A1/fr not_active Abandoned
  • 2002-04-09 CN CNA028097629A patent/CN1507632A/zh active Pending
  • 2002-04-09 KR KR10-2003-7013426A patent/KR20040002912A/ko not_active Application Discontinuation
  • 2002-04-09 EP EP02761930A patent/EP1386325A1/fr not_active Withdrawn
  • 2002-04-09 WO PCT/FR2002/001244 patent/WO2002084670A1/fr not_active Application Discontinuation
  • 2002-04-09 JP JP2002581529A patent/JP2004530874A/ja active Pending
• 2003
  • 2003-10-13 ZA ZA200307951A patent/ZA200307951B/en unknown

Patent Citations (6)

Non-Patent Citations (5)

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