EP4282018A1 - Ensemble pile à combustible doté de deux systèmes de pile à combustible parallèles - Google Patents

Ensemble pile à combustible doté de deux systèmes de pile à combustible parallèles

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Publication number
EP4282018A1
EP4282018A1 EP22700416.5A EP22700416A EP4282018A1 EP 4282018 A1 EP4282018 A1 EP 4282018A1 EP 22700416 A EP22700416 A EP 22700416A EP 4282018 A1 EP4282018 A1 EP 4282018A1
Authority
EP
European Patent Office
Prior art keywords
fuel cell
cell system
cathode
air
anode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22700416.5A
Other languages
German (de)
English (en)
Inventor
Oliver Harr
Philipp Hausmann
Benjamin Pieck
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cellcentric GmbH and Co KG
Original Assignee
Cellcentric GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE102021000329.2A external-priority patent/DE102021000329A1/de
Application filed by Cellcentric GmbH and Co KG filed Critical Cellcentric GmbH and Co KG
Publication of EP4282018A1 publication Critical patent/EP4282018A1/fr
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04097—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with recycling of the reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04111—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants using a compressor turbine assembly
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
    • H01M8/04126—Humidifying
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/249—Grouping of fuel cells, e.g. stacking of fuel cells comprising two or more groupings of fuel cells, e.g. modular assemblies
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the invention relates to a fuel cell system with two parallel fuel cell systems, each of which comprises at least one fuel cell stack with anode-side and cathode-side periphery. They also include a common air conveyor.
  • An exemplary fuel cell system can be found in DE 102009 043 569 A1.
  • This system provides on the one hand a system bypass for connecting the pressure side to the exhaust air side and on the other hand a connection between the anode side and the cathode side via a blow-off line with a so-called blow-off or purge valve.
  • a gas/gas humidifier that is customary in such fuel cell systems is indicated, which is used to humidify the supply air flow to the cathode space of the fuel cell through its moist exhaust air flow.
  • these components are relatively large, complex and expensive.
  • So-called electric turbochargers are often used for air supply in conventional fuel cell systems, which have a compressor wheel on one side and a turbine on the other side, symmetrically to an electric machine. This allows power to be recovered from the exhaust air of the fuel cell system via the turbine.
  • the load on the electric turbocharger is relatively high and that it has to be set up in a correspondingly complex manner, especially with regard to its axial bearings, since the force ratio between the turbine wheel on the one hand and the compressor wheel on the other hand causes high loads on the axial bearing.
  • a further problem with the sensible use of flow compressors lies in their operating behavior, so that the desired ratio of volume flow to pressure often cannot be provided for the respective fuel cell system, or cannot be provided without blowing off already compressed air. This is also undesirable and in particular reduces the overall efficiency of the system, since air that has already been compressed remains unused in order to be able to set the desired ratio of pressure and volume flow through the flow compressor.
  • the object of the present invention is now to specify an improved fuel cell system with at least two parallel fuel cell systems, which is improved in particular with regard to the air supply.
  • the fuel cell system with the two or more parallel fuel cell systems has a common air conveying device.
  • this air conveying device is designed as a two-stage air conveying device. Both stages are realized in the form of flow compressors, which each have a compressor wheel per stage.
  • the compressor wheels for one and the other fuel cell system are arranged symmetrically to at least one electrical machine on a shaft. This enables a structure in which the symmetrical arrangement of the compressor wheels and the electrical drive arranged between them, a very good balance of axial forces is possible. This increases efficiency because friction can be minimized. In addition, simpler and smaller thrust bearings are possible, which is another advantage.
  • each of the stages has an electric drive machine and two compression wheels arranged symmetrically thereto for one and the other fuel cell system.
  • two flow compressors each with two compressor wheels arranged symmetrically to the electric machine, are connected in series in the manner of register charging.
  • the structure is operated isobaric in particular in order to achieve a good air supply for the two fuel cell systems at all or at least most of the required operating points efficiently and without having to blow off already compressed air.
  • the compressor wheels on one side of the electric motors supply one fuel cell system as a two-stage system and the compressor wheels on the other side of the electric machines take over the air supply of the other fuel cell system.
  • the structure also enables a high degree of flexibility in a manner that will be described in more detail later, since, for example, exhaust gas recirculation lines, humidification and the like are installed both in front of one and in front of the other stage and can therefore be placed between the two stages.
  • the second stage can, for example, take on special tasks that will be described later in order to maintain the basic functionality and service life of the two fuel cell systems of the fuel cell system, for example by recirculating exhaust gas or the like.
  • the fuel cell stacks of the fuel cell systems are connected in series.
  • the waiver of complicated elements of the power electronics which must be present twice in such a fuel cell system and are accordingly expensive and complex and require a lot of space, is also possible with the mentioned electrical series connection of the fuel cell stacks because they can then be operated with a constant fuel cell current .
  • the voltage can then be influenced solely via the stoichiometry.
  • the oxygen content can be increased accordingly by increasing the air volume via the two-stage air supply of the air conveying device.
  • At least one of the fuel cell stacks in particular the fuel cell stack of one of the fuel cell systems, has a freewheeling diode parallel to the fuel cell stack or stacks, so that operation is possible even if one of the fuel cell systems fails, but then with reduced voltage, so that, for example, a Trucks equipped with such a fuel cell system can at least offer an emergency functionality, for example to drive to a workshop or to a hub in autonomous operation in order to check and/or service the fuel cell system accordingly.
  • each fuel cell system has what is known as an anode circuit, which is used for the recirculation of unused fuel, in particular hydrogen. This is recirculated around the anode space of the fuel cell stack or the two fuel cell stacks electrically connected in series in each of the fuel cell systems, ie fed back from the output of the anode space to the input. In the case of two fuel cell stacks per fuel cell system, these are fluidly connected in parallel for this purpose. In most operating situations, exhaust gas mixed with fresh hydrogen is fed back to the anode chamber in a manner known per se via the anode circuit.
  • Each of the fuel cell systems also includes a cathode bypass, e.g. a line that is parallel to the cathode.
  • this cathode bypass branches off before or in the area of a valve device in the supply air line and opens into the exhaust air line after or in the area of a further valve device. All of this can be built around the cathode space of the fuel cell stack or stacks on the system side. However, it can also be fully or partially integrated into them and/or their housing.
  • the cathode chamber of one fuel cell stack or the cathode chambers of the two fuel cell stacks electrically connected in series, which are fluidically connected in parallel, are referred to below simply as the “cathode chamber”. This is done in the "anode room analog”.
  • the cathode space can be shut off and the air actually flowing towards and through the cathode space can be shut off through the cathode bypass.
  • Mixed forms of these two operating states are conceivable, possible and often useful.
  • a gas jet pump driven by the air flowing around the cathode chamber is arranged in the cathode bypass.
  • the gas jet pump is therefore driven by this air as a driving jet.
  • the gas jet pump is connected in a switchable manner both to the anode compartment and to the cathode compartment.
  • a fan is driven as a recirculation conveying device by an exhaust air turbine in the exhaust air line.
  • Energy in the exhaust air can thus be used in the respective fuel cell system of the fuel cell installation. In contrast to many conventional fuel cell systems, this energy should not be used in an electric turbocharger to support the compression of the supply air, but to recirculate the anode exhaust gases in the anode circuit.
  • a particularly favorable embodiment of the fuel cell system according to the invention also provides that in each of the fuel cell systems at least one humidifier is arranged in the supply air before and/or after the second compressor stage, which is designed in particular in the form of a one- or two-material nozzle.
  • the humidifier can therefore be designed simply in the form of a one- or two-component nozzle.
  • These humidifiers can be arranged in the supply air before and/or after the second compressor stage.
  • This atomized water helps keep the hot when compacting to cool the air that is being generated and is thereby evaporated in the air, so that it is ideally humidified.
  • Humidification can take place independently of the operation of the fuel cell, particularly when the corresponding humidifier is electrically driven, which is another very important advantage over a much more complex, larger and more expensive gas/gas humidifier, which can be saved with this design.
  • the only attached figure shows a schematic representation of a fuel cell system according to the invention.
  • the fuel cell system 1 shown in the figure comprises a common air conveying device 2, which is designed here in the form of two flow compressors 3, 4 connected in series in two stages.
  • Each of the two flow compressors 3, 4 comprises an electric drive machine 5, 6 and, together with the respective electric drive machine 5, 6, arranged on a common shaft 7, two symbolically illustrated compressor wheels 8, 9 on one, here the left, and 10, 11 on the other, here the right side.
  • the intake air reaches the compressor wheels 9, 11 of the first stage via a common air filter 12.
  • the air filter 12 can, for example, be constructed as an activated carbon filter or, in particular, include such a filter in order to protect the fuel cell system not only from particles and dust but also from undesired chemical loads in the intake air.
  • the two flow compressors 3, 4 can be magnetically mounted, for example. They are in two stages and thus connected in series on each of their sides and are operated isobaric.
  • the right side of the structure with the compressor wheels 8, 9 supplies a first fuel cell system 13 with air.
  • the other side with the compressor wheels 10, 11 supplies an identically constructed fuel cell system 14 on the other side of the figure.
  • Each of these two fuel cell systems 13, 14 comprises two fuel cell stacks 15, 16 and 17, 18, which are fluidic, i.e.
  • each of the fuel cell systems 13, 14 are connected in parallel to one another and, for example, obtain hydrogen from a common hydrogen source, which is shown here twice and is each designated 19, which is designed in particular as a structure made up of a large number of compressed gas storage devices, cryogenic storage devices, metal hydride storage devices or, in principle, systems for on-board hydrogen production could be.
  • the respective fuel cell stacks 15, 16 of one fuel cell system 13 and the fuel cell stacks 17, 18 of the other fuel cell system 14 are all connected in series, as indicated here by the schematically indicated electrical connection to an exemplary battery system designated 21 for hybridizing the fuel cell system 1 .
  • an exemplary battery system designated 21 for hybridizing the fuel cell system 1 .
  • a current flowing to the fuel cell stacks 15, 16 and 17, 18, which would cause electrolysis there is prevented via a blocking diode 20.
  • One of the fuel cell systems 13, 14 can thus be bypassed for emergency operation if it fails.
  • the two fuel cell systems 13, 14 are designed identically to one another and are shown here mirrored, with both fuel cell systems 13, 14 using their own peripheral parts and components on the cathode and anode side, for example water separators, an anode circuit, a cathode circuit, an anode recirculation fan and the like. They can have a common water supply system 23, which will be discussed in more detail in the following explanation.
  • the compressor wheels 8, 10 and 9, 11 of both stages are designed symmetrically and the respective electric machine 5, 6 as a drive lies in between on the same shaft 7 work, minimized. On the one hand, this helps to reduce friction losses and, on the other hand, allows axial bearings to be designed in a simple and efficient manner. Via a common intake path or optionally also via two separate intake paths, air is sucked in through the air filter 12 by the compressor wheels 8 , 10 of the first flow compressor 3 .
  • the compressed air reaches the compressor wheel 9 and 11 of the second flow compressor 4 via a register line 24, 25 it is therefore a register charge.
  • the two flow compressors 3, 4 work isobaric in particular.
  • a bypass line 28 is provided, each with a valve 29, 30 on the respective register line 24, 25, which in principle makes it possible to blow compressed air between the stages.
  • the fuel cell system 14 includes the two fuel cell stacks 17, 18, which are typically a stack of individual cells. They are connected electrically in series and fluidically in parallel. This applies to the fuel cell stack 15, 16 of the other fuel cell system 13 analogously. Unlike the components described below, these still have their own reference symbols due to the above explanation of the electrical wiring.
  • the two fuel cell stacks 17, 18 each comprise an anode compartment 31 and a cathode compartment 32. These are provided with the same reference numbers in both fuel cell stacks 17, 18 and act as if they were an anode compartment 31 and a cathode compartment 32 due to the fluidically parallel connection only one anode space 31 or cathode space 32 is spoken of, even if both are meant.
  • the cathode chamber 32 is now supplied with air via the air supply line 27 via the air conveying device 2 with its two stages.
  • Exhaust air arrives via an exhaust air line 33 at a valve device denoted by 34 , this valve device 34 also being able to be designated as an exhaust air or exhaust gas recirculation valve 34 .
  • this valve device 34 the exhaust air from the exhaust air line 33 in whole or in part via an exhaust air return line 35 in the bypass line 28 and from there into the Register lines 24, 25 are returned, or via the designated 36 part of the exhaust air line to an exhaust air turbine 37, which will be explained in more detail later.
  • the anode space 31 is supplied with hydrogen from the hydrogen storage device 19 .
  • This hydrogen reaches the anode chamber 31 via a pressure control and metering device 38.
  • Exhaust gas returns from the outlet of the anode chamber 31 to its inlet via an anode circuit with a recirculation line designated 39, in which a water separator 40 can be arranged, and flows into the mixed with fresh hydrogen into the anode chamber 31 in most operating states.
  • a recirculation fan 41 can be arranged in the recirculation line 39 as an alternative or in addition to a gas jet pump (not shown).
  • blow-off line 42 with what is known as a blow-off valve or purge valve 43 or purge/darin valve, via which, for example, depending on the time, depending on the hydrogen concentration in the recirculation line 39, or depending on other parameters, gas from the recirculation line 39, optionally together with water from the water separator 40, is drained.
  • valve device 44 in the direction of flow in front of the cathode chamber 32 and a valve device 45 is arranged in the direction of flow after the cathode space 32.
  • valve devices 44, 45 can preferably, and this is how it is shown here, be designed as 3/2-way valves. Essentially, however, they could also be realized by independent valve devices, which are arranged both in the supply air line 27 and in the exhaust air line 33 and which would also be arranged in a cathode bypass 46 .
  • the cathode bypass 46 can be switched via the valve devices 44 , 45 , specifically with the cathode space 32 closed off or the volume comprising the cathode space 32 closed off.
  • the cathode bypass 46 is provided with a gas jet pump 47, which can be designed, for example, in the manner of a Venturi tube.
  • gas jet pump 47 can be designed, for example, in the manner of a Venturi tube.
  • any other type of gas jet pump or ejector or jet pump is also conceivable, as long as gases can be sucked in as a propellant gas flow from the air flowing around the cathode chamber 32 by negative pressure effects and/or momentum exchange.
  • the gas jet pump 47 is connected to the blow-off line 42 , which can be switched via the purge valve 43 in order to connect the recirculation line 39 to the gas jet pump 47 .
  • the purge valve 43 in order to connect the recirculation line 39 to the gas jet pump 47 .
  • the gas jet pump 47 is also connected on the suction side via a cathode branch line 48 and a cathode suction valve 49 arranged therein to the cathode chamber 32 or to the volume lying between the valve devices 44, 45 and comprising the cathode chamber 32.
  • the cathode branch line 48 can be arranged both before and after the cathode chamber 32 , that is to say with an opening into the air supply line 27 or the exhaust air line 33 . In principle, a direct connection to the fuel cell stack 17, 18 would also be conceivable, but this is technically far more complex than branching off from the corresponding line 27, 33.
  • gas can now be discharged through the gas jet pump 47 with the cathode suction valve 49 open when the cathode bypass 46 is in flow the cathode chamber 32, which means that when the valve devices 44, 45 are closed, a negative pressure can also be generated in the cathode chamber 32. This will also be explained in more detail later with regard to the particularly advantageous use.
  • the recirculation fan 41 which is driven by the turbine 37 in the part of the exhaust air line 33 designated by 36, can also be bypassed via a turbine bypass 50 if necessary. This has a throttle point 51 .
  • the exhaust air turbine 37 can be bypassed by the exhaust air via a valve device 52, which is also designed here as a 3/2-way valve, so that the recirculation fan 41 is not driven.
  • a further valve device 53 is provided, which is connected via a line 54 to the section 36 of the exhaust air line 33 and thus allowing air to be injected directly into the area of the exhaust air turbine 37 .
  • the line 54 thus forms a “classic” system bypass.
  • the liquid water system 23 already mentioned can preferably be filled with water which is recovered from the fuel cell system 14 .
  • the fuel cell system 14 typically has the water separator 40 in the recirculation line 39 and another water separator 55 in the area of the exhaust air line 33, and here if possible before the exhaust air turbine 37.
  • the water from the water separator 40 reaches the gas jet pump 47 and the cathode bypass 46 also into the water separator 55.
  • a parallel line would also be possible from the water separator 40, for example, into the water separator 55 or directly into a water tank 57 of the liquid water system 23, in which all the water from all the water separators 40, 55 of the fuel cell system 14 and also of the fuel cell system 13 collects.
  • a water line designated 56 is shown for this purpose, starting from the water separator 55 , which is taken up again in the drawing in the area of the liquid water system 23 and opens into the water tank designated 57 .
  • heat can be supplied to the water, for example via electrical heating.
  • this can be formed by the freewheeling diodes 22 and their cooling as well as by the additional cooling of other power electronic components not shown here, such as a common PDU for the fuel cell stacks 15, 16, 17, 18 of the two fuel cell systems 13, 14.
  • the water stored in the water tank 57 ideally has a temperature of approx. 80° C., the water tank 57 therefore preferably has thermal insulation (not shown) in order to prevent the water tank 57 from cooling down quickly and unnecessarily.
  • the insulated water tank 57 is followed by a water treatment system, designated 60, which can have corresponding water filters and ion exchangers.
  • the liquid water collected from the two fuel cell systems 13, 14 is then used to humidify the supply air flowing to the fuel cell stacks 15, 16, 17, 18.
  • the explanation is again only on the side of the fuel cell system 14 and is to be understood analogously in the case of the fuel cell system 13 .
  • Two branch lines 62, 63 are supplied with water via the supply line 61, which can be designed, for example, as a pressurized water line in the manner of a common rail and is supplied with water from the water tank 57 via a water pump 59, which branch lines can each be switched via the Valves designated 65 promote water to the humidifier 67 in the register line 24 and a humidifier 68 in the supply air line 27, ie after the second flow compressor 4.
  • Each of the humidifiers 67, 68 is preferably designed as a simple humidifier that atomizes the water with a single-component nozzle or a two-component nozzle. For example, it can be operated with electrical energy and thus independently of the operation of the fuel cell system 1 and controlled with regard to humidification. This means that, together with the exhaust gas recirculation, a complex conventional gas/gas humidifier can now be dispensed with during operation.
  • This structure of the liquid water system 23 is also used in a similar way in internal combustion engine drives, in particular internal combustion engines with petrol injection.
  • the components such as the water pump 59, the heatable water tank 57 and the humidifier 67, 68 are therefore available on the market as sufficiently tried and tested parts in large numbers and are therefore available at low cost.
  • the hydrogen supply can be stopped. With the remaining volume flow when the flow compressors 3 , 4 coast down, gas can then be sucked out of the blocked cathode space 32 and the anode circuit and thus out of the anode space 31 .
  • the (no-load) voltage of the fuel cell stacks 15, 16, 17, 18 can be reduced very quickly when the load is shed and the current is reduced to zero, in order to prevent the occupants of the vehicle and rescue workers from being endangered.
  • the oxygen content in the fuel cell stacks 15, 16, 17, 18 can be reduced in order to limit the cell voltage, for which purpose a corresponding amount of oxygen-depleted exhaust air is recirculated via the exhaust gas recirculation valve 34 and the exhaust gas recirculation line 35, thereby also supporting the humidification of the supply air . If this is not sufficient, oxygen can also be actively sucked out of the cathode chamber 32 when the cathode suction valve 49 is open, by routing part of the supply air via the cathode bypass 46 and the gas jet pump 47, in order to limit the voltage in the individual cells in a more reliably controllable manner .
  • this possibility of influencing the stoichiometry of the individual fuel cell stacks 15, 16, 17, 18 more or less downwards can also be reversed by the two stages of the air conveying device 2.
  • the structure of the fuel cell system consisting of 980 individual cells, for example, can be controlled solely via the stoichiometry of the four fuel cell stacks 15, 16, 17, 18 mentioned with regard to the voltage.
  • This therefore means that with a constant current from the fuel cell stacks 16, 16, 17, 18 of the fuel cell system 1, the provided and required voltage can be set according to the required operating points solely via the stoichiometry.
  • the oxygen content can be increased by the two isobaric flow compressors 3, 4, and the oxygen content can be reduced when supplying the cathode compartment 32 by means of the exhaust gas recirculation measures described above through to the active extraction of oxygen-containing gas from the cathode compartment 32 .
  • Two very crucial points for the operation of the fuel cell system 14 relate to a preparation for a freeze start, a so-called FSU (Freeze Start Up) preparation.
  • FSU Freeze Start Up
  • the pressure in the anode compartment 31 and in the cathode compartment 32 for example down to 100 mbar
  • water present in both the anode compartment 31 and in the cathode compartment 32 can be evaporated and actively sucked off via the gas jet pump 47. This can take place, for example, in a temperature window of 25 to 35° C. for the fuel cell stacks 17, 18.
  • the membranes are largely prevented from drying out, so that the fuel cell stacks 17, 18 can be dried very gently.
  • the fuel cell stack 17, 18 can be prevented from freezing beyond a desired or tolerable level. If the temperatures rise above freezing again, active humidification can be carried out even without the fuel cell stacks 17, 18 being actively started, since liquid water is available via the liquid water system 27 and, for example, via the humidifier 68, which in particular is designed as an electric operated humidifier can be designed with single-component nozzle, can be easily and efficiently introduced into the supply air. As already mentioned, this can be circulated via the exhaust gas recirculation valve 34 in order to keep the membranes sufficiently moist on the one hand and on the other hand to be prepared for a freezing start at any time.
  • a strategy that has been customary up to now for preparing for the start is to achieve as long a time as possible in which an air/hydrogen front is prevented in the anode space 31 when the fuel cell system is started. This always occurs when the hydrogen has diffused out of the anode chamber 31 and air has penetrated. If fresh hydrogen is then replenished, this dreaded front occurs, which damages the anode accordingly and has an extraordinarily disadvantageous and severe effect on the service life of the fuel cell stacks 17, 18.
  • the fuel cell system 14 in the embodiment variant shown here now has several options for preventing such an air/air start.
  • the first possibility is that the cathode space 32 can be appropriately evacuated. If there is no oxygen in this, the front cannot develop its damaging effect even if oxygen is present on the anode side and is displaced by hydrogen flowing in during the start.
  • This easy way it can provide, for example, for the cathode to be permanently kept free of oxygen, which, given the tightness that usually occurs in the system, requires the cathode compartment 32 to be evacuated again, for example, every ten hours or the like. Since such a recurring evacuation is relatively risky for the membranes, since they can dry out, this procedure can be accompanied in particular by the humidification of the membranes described above when the temperatures are above freezing point and a safe and reliable start even with a certain residual moisture in the fuel cell system 1 is possible.
  • a second possibility of avoiding an air/air start is that the air which also enters the anode chamber while the fuel cell system 14 is at a standstill
  • the third option uses the generation of nitrogen or oxygen-depleted air, in particular air with an oxygen content of 0%, in order to achieve a very gentle start.
  • nitrogen or oxygen-depleted air in particular air with an oxygen content of 0%
  • the fourth option for avoiding an air/air start is to a certain extent a combination of the second and the third option.
  • a hydrogen metering line is also required for this, via which hydrogen can be metered onto the cathode side.
  • This hydrogen metering line is connected to the gas jet pump 47 in the cathode bypass 46 in a manner similar to or as an alternative to the purge line 42 . It is thus possible to meter hydrogen via the hydrogen metering line onto the cathode side of the fuel cell system 14 without this hydrogen having to flow through the anode space 31 beforehand. Oxygen in the air can thus be consumed by the catalytic converter already mentioned above, which is connected downstream of the gas jet pump 47 in the circuit around the cathode space 32 .
  • This gas is heated at the same time by the recirculation via the compressor wheel 11, which promotes the catalytic reaction in the catalyst in order to convert oxygen and hydrogen efficiently.
  • a temperature range of approx. +60 to +80° C is ideal for this. This allows the catalytic conversion to be controlled very well in order to avoid unwanted nitrogen oxides within the closed volume. These nitrogen oxides as a by-product are undesirable due to the emissions of the same occurring later, but would not further impair the service life of the fuel cell stacks 17, 18.
  • the purge valve 43 can be opened and the second flow compressor 4 can be switched off.
  • the cathode suction valve 48 and/or the valve devices 44, 45 are opened.
  • the nitrogen then flows back into the fuel cell stack 17, 18 via the purge line 42 and the cathode branch line 48 and/or the air supply line 27, so that these are filled with nitrogen. This enables an extraordinarily gentle start during the next start process, without the damaging mechanisms of the air/air start occurring.
  • a fifth possibility can also be ideally used in the construction of the fuel cell system 14 in combination with the previously customary way of keeping the hydrogen in the system.
  • the volumes of both the anode chamber 31 and the cathode chamber 32 are filled with hydrogen and kept under a slight overpressure in order to ensure that the volume is completely inerted by a hydrogen concentration of almost 100 percent realize.
  • the residual hydrogen present in the cathode compartment 32 can now be removed again via the gas jet pump 47 and its operation by the supply air that has already been pumped but does not flow into the cathode compartment 32, in that the hydrogen is completely sucked out of the cathode compartment 32 before the cathode compartment 32 is then acted upon by opening the valve device 44 in the direction of the cathode space 32 with oxygen or the oxygen-containing air in order to start the fuel cell system 14 or its fuel cell stack 17, 18 can.
  • the fuel cell stacks 17, 18 can be evacuated again using the gas jet pump 47 in the cathode bypass 46. With the purge valve 43 open, the Air compressor air or oxygen-containing gas in the area of the anode chamber 31 reach. In principle, the passive oxidation of carbon monoxide to carbon dioxide is conceivable.
  • the air conveying device 2 or one of its stages is operated again with the purge valve 43 initially closed, in order to drive the recirculation conveying device 41 in the form of the blower via the exhaust air turbine 37 in the exemplary embodiment shown here.
  • the refresh of the catalyst is then completed after a short time, for example on the order of less than a minute.
  • the oxygen-containing gas can then be sucked out of the anode circuit again by opening the purge valve 43 again, and the system can be filled with nitrogen, for example, in the manner described above, in order to prepare it for the next start.

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  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fuel Cell (AREA)

Abstract

L'invention concerne un ensemble pile à combustible (1) doté de deux systèmes de piles à combustible (13, 14) parallèles, comprenant chacun au moins un empilement de piles à combustible (15, 16, 17, 18) présentant une périphérie du côté de l'anode et du côté de la cathode et disposant d'un dispositif commun de transport d'air (2). L'ensemble pile à combustible (1) selon l'invention est caractérisé en ce que le dispositif de transport d'air (2) est à deux étages, les deux étages se présentant sous la forme de compresseurs d'écoulement (3, 4) ayant chacun une roue de compresseur (8, 9, 10, 11) par étage, les roues de compresseur (8, 9 ; 10, 11) pour l'un et l'autre système de pile à combustible (13 ; 14) étant disposées symétriquement par rapport à au moins une machine électrique (5, 6) sur un arbre (7).
EP22700416.5A 2021-01-22 2022-01-20 Ensemble pile à combustible doté de deux systèmes de pile à combustible parallèles Pending EP4282018A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102021000329.2A DE102021000329A1 (de) 2021-01-22 2021-01-22 Brennstoffzellenanlage mit zwei parallelen Brennstoffzellensystemen
DE202021103104 2021-01-22
PCT/EP2022/051218 WO2022157237A1 (fr) 2021-01-22 2022-01-20 Ensemble pile à combustible doté de deux systèmes de pile à combustible parallèles

Publications (1)

Publication Number Publication Date
EP4282018A1 true EP4282018A1 (fr) 2023-11-29

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EP22700416.5A Pending EP4282018A1 (fr) 2021-01-22 2022-01-20 Ensemble pile à combustible doté de deux systèmes de pile à combustible parallèles

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US (1) US20240063405A1 (fr)
EP (1) EP4282018A1 (fr)
KR (1) KR20230122644A (fr)
WO (1) WO2022157237A1 (fr)

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Publication number Priority date Publication date Assignee Title
DE102022208656A1 (de) * 2022-08-22 2024-02-22 Robert Bosch Gesellschaft mit beschränkter Haftung Brennstoffzellensystem, Verfahren zum Betreiben eines Brennstoffzellensystems
DE102022209491A1 (de) * 2022-09-12 2024-03-14 Robert Bosch Gesellschaft mit beschränkter Haftung Brennstoffzellensystem und Verfahren zum Betreiben eines Brennstoffzellensystems

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DE10203030A1 (de) * 2002-01-26 2003-07-31 Ballard Power Systems Brennstoffzellensystem mit einer Druckwechseladsorptionseinheit
DE10312647A1 (de) * 2003-03-21 2004-09-30 Ballard Power Systems Ag Brennstoffzellensystem und Verfahren zum Betreiben eines Brennstoffzellensystems
DE102009043569A1 (de) 2009-09-30 2011-04-07 Daimler Ag Verfahren zum Betreiben eines Brennstoffzellensystems

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US20240063405A1 (en) 2024-02-22
KR20230122644A (ko) 2023-08-22
WO2022157237A1 (fr) 2022-07-28

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