AT521064B1 - Stacked fuel cell system - Google Patents

Abstract

The invention relates to a fuel cell system (1), in particular an SOFC system, the fuel cell system (1) being constructed in a stack, comprising at least one fuel cell stack (2) with a cathode section (3) and an anode section (4), at least one end plate (5 ) and at least one gas processing plate (7), the fuel cell stack (2) being arranged at least in regions above the end plate (5), characterized in that at least one intermediate plate (6) is provided, the intermediate plate (6) at least in regions above the gas processing plate (7) and the end plate (5) is arranged at least in regions above the intermediate plate (6). The invention further relates to the use of such a fuel cell system (1).

Description

description

The fuel cell system, in particular an SOFC system, the fuel cell system being constructed in a stack-like manner, comprising at least one fuel cell stack with a cathode section and an anode section, at least one end plate and at least one gas processing plate, the fuel cell stack at least in regions the end plate is arranged.

[0002] The invention further relates to the use of such a fuel cell system.

[0003] SOFC systems (“solid oxide fuel cell”) with one or more fuel cell stacks for converting chemical energy into electrical energy are known in the prior art. In such SOFC systems, so-called gas processing devices (GPU, English for "gas processing units") are known. Gas processing devices are to be understood as all those auxiliary devices in the fuel cell system that contribute to the provision of process gas that can be processed in a fuel cell stack of the fuel cell system. In SOFC systems, gas processing devices can include heat exchangers, reformers, afterburners, starting burners, evaporators, and the like. In addition, fuel cell systems known from the prior art include so-called distributor plates, which are necessary in order to connect the gas processing devices to the fuel cell stack in terms of flow technology and mechanically.

The respective gas processing devices and distributor plates take up an essential part of the available space in the fuel cell system. In the case of mobile applications in particular, it must always be kept small or used as efficiently as possible.

Fuel cell systems in which this problem is partially taken into account are known, for example, from US 2009053569 A1 and WO 2007087240 A2.

[0006] This is where the invention comes in. The object of the invention is to provide a fuel cell system which is as compact as possible and which can be arranged in a space-saving manner in a motor vehicle.

Another aim is to specify the use of such a fuel cell system.

The object is achieved in that at least one intermediate plate is provided in a fuel cell system of the type mentioned, the intermediate plate is at least partially arranged above the gas processing plate and the end plate at least partially above the intermediate plate.

An advantage achieved in this way can be seen in particular in that the plate-like design of the gas processing plate and the stack-like arrangement of the elements relative to one another, the gas processing plate and the fuel cell stack one above the other, that is to say can be arranged along a line. The intermediate plate is particularly preferably arranged completely above the gas processing plate and the end plate completely above the intermediate plate. As a result, a substantially space-saving solution for arranging the elements is created in comparison to fuel cell systems known from the prior art. The intermediate plate is substantially thinner than the gas processing plate and is made of distributor plates known from the prior art. In addition, the plate-like structure, in particular of the gas processing plate and the layered arrangement of the plates and the fuel cell stack with respect to one another, provide an extremely compact arrangement of the entire fuel cell system, as a result of which there is less complex thermal insulation of the individual elements and / or plates than in the prior art necessary is.

As already mentioned above, there is a device under the gas processing plate

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AT 521 064 B1 2020-03-15 Austrian patent office to understand, which includes all those auxiliary devices or elements in a fuel cell system that contribute to ensuring the provision of gas usable in a fuel cell stack of the fuel cell system. In SOFC systems, such gas processing plates can include, for example, heat exchangers, reformers, exhaust gas burners, starting burners and / or evaporators.

It is advantageous if the fuel cell stack, the end plate, the intermediate plate and the gas processing plate are in particular non-positively connected to one another. These are particularly preferably screwed together. This creates a compact fuel cell system which comprises a plurality of plate-shaped interconnected elements.

It is advantageous if the gas processing plate and the intermediate plate have the same or approximately the same cross-sectional area. This further simplifies the arrangement of these two plates with respect to one another and the connection thereof. This also applies to the manufacture of the panels. The end plate advantageously has approximately the same cross-sectional area as the fuel cell stack itself, the cross-sectional area of the end plate being in particular smaller than the cross-sectional area of the intermediate plate.

It is expedient if the end plate has at least one passage for an oxygen-containing fluid and a passage for reformed fuel, the end plate being designed in particular as an integral element of the fuel cell stack. The oxygen-containing fluid is conveyed through the end plate in the direction of a cathode section of the fuel cell stack. According to the invention, the end plate can also have two or more passages for the oxygen-containing fluid and / or the fuel. The fully reformed fuel is conveyed through the passage in the end plate towards an anode portion of the fuel cell stack. The end plate is in particular an end plate of the fuel cell system, which is why it is preferably designed as an integral component of the same. The passages are designed as lines or line sections or connect individual line sections, through which the operating fluids are guided from respective operating fluid sources in the direction of the fuel cell stack and from there to the environment. In addition, the end plate has at least one passage for fuel cell stack waste gas, in particular at least one passage for anode waste gas and a passage for cathode waste gas which is separate from the flow.

An oxygen-containing fluid is to be understood in the context of the invention as a first operating fluid, in particular gaseous air or another oxygen-containing, gaseous fluid. The oxygen-containing fluid is particularly preferably ambient air. Fuel is a second operating fluid according to the invention. In the context of the invention, a liquid fuel such as ethanol, methanol, ammonia or diesel is used in particular as fuel. However, a gaseous fuel or a fuel-water mixture can also be used. A fuel source and an air source are further provided, which are arranged downstream of the gas processing plate and outside the same and are connected to respective lines or line sections for conducting the operating fluids. The operating fluids are routed via lines and line sections provided in the various plates arranged in a stack-like manner with respect to one another. For this purpose, in particular at least one cathode supply line for leading air to the cathode section, one anode supply line for leading fuel to the anode section and one fuel cell stack exhaust line or at least one cathode exhaust line and one anode exhaust line for leading cathode exhaust gas and anode exhaust gas to the surroundings are provided. According to the invention, the lines run through all plates. The lines can advantageously include partial lines, wherein different elements of the fuel cell system can be arranged in the lines. The lines or partial lines can connect individual components of the fuel cell system as well as individual plates thereof.

[0015] In the present case, under one line there is in particular a line system with several Lei

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AT 521 064 B1 2020-03-15 Austrian patent office sections. The supply and exhaust lines are not only to be understood as line sections to the fuel cell stacks, but in particular also line sections between and within the individual plates.

It is advantageous if the intermediate plate has at least one passage for an oxygen-containing fluid, a passage for reformed fuel and has a feed line from a further oxygen-containing fluid. Before the operating fluids pass through the end plate, they are passed through the intermediate plate. In principle, it can be favorable if the intermediate plate for the operating fluids which are fed to the fuel cell stack has no other function than the indirect distribution thereof from the gas processing plate to the fuel cell stack. Via the supply line of a further oxygen-containing fluid, either a bypass line which branches off from the air source or fresh air can be supplied via a separate source downstream of a cathode heat exchanger arranged in the gas processing plate and upstream of the cathode section of a cathode supply line. This is particularly advantageous because it allows a temperature of the air conducted in the cathode supply line to be regulated or adjusted so that the temperature of the air which is conducted into the cathode section can be determined. The intermediate plate comprises line section and passages for the operating fluids as well as lines which are guided into the intermediate plate from outside the plates arranged in a stack. This is designed and arranged for distributing and / or mixing operating fluids. Passages for anode exhaust gas, cathode exhaust gas or already merged fuel cell exhaust gas are also provided in the intermediate plate.

It is advantageous if the gas processing plate comprises a reformer, an afterburner and at least one cathode heat exchanger, the gas processing plate forming a hot box. In addition, the gas processing plate comprises several lines and partial lines. It can also be favorable if the gas processing plate also comprises a starting burner and an evaporator. The gas processing plate thus comprises all the elements that are necessary to process fuel and air in such a way that they can be processed in the fuel cell stack. The elements are formed in the gas processing plate and arranged relative to one another in such a way that the gas processing plate is made as compact as possible. These are preferably adjacent to one another or directly adjacent to one another. In principle, it can also be favorable if the starting burner is arranged outside the gas processing plate, preferably it can be designed as a separate plate, which is either arranged in the same plane as the gas processing plate or under the gas processing plate. It can also be expedient if the evaporator is arranged outside the gas processing plate, for example in the same plane as the gas processing plate or below it. Within the scope of the invention, a hot box is to be understood as the area in which the elements are arranged which have a high temperature or require them to function. In principle, it can be favorable if the fuel cell stack itself and the intermediate plate and the end plate are also arranged in the hot box. The hot box is advantageously heat-insulating from the surroundings.

The heat-exchanging components and catalytic coatings enable functional integration of the gas processing plate into flow channels.

It is useful if the reformer is designed as part of a coated heat exchanger, with a fuel to be reformed flowing through a cold side of the heat exchanger. The reformer can in particular be part of a plate heat exchanger. The heat transfer elements of the reforming area of the heat exchanger comprise a catalytic material, so that a catalytic reaction necessary for a reforming process can be carried out. Heat transfer elements are particularly preferably coated with a catalytic material. The catalytic coating used can be applied directly to the structure of the heat exchanger or can be designed as an inserted coated network. The fuel is advantageously already supplied to the reformer in gaseous form and overheated. However, it can also be provided that the area of reform

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AT 521 064 B1 2020-03-15 Austrian patent office is designed together with an overheating area. This means that the fuel can be overheated and reformed in one step or at least very quickly in succession. It is advantageous if the catalytic coating is designed as a catalytic fabric or a catalytically coated, in particular metallic, grid. It is particularly expedient if the heat transfer elements of the reformer are coated with a catalytic fabric or the catalytically coated grid. The catalytic coating is designed to reform the vaporized and possibly overheated fuel. The reforming is advantageously carried out by steam reforming without the addition of air or steam. In particular, when using a water-containing fuel such as an ethanol-water mixture, no separate supply of (water) steam is necessary. The amount of steam required for steam reforming is already provided by the vaporized fuel itself. An endothermic reaction takes place during steam reforming. The energy required for this is provided according to the invention via the system exhaust gas, which is coupled to the reformer for heat transfer. The heat exchanger can be flowed through in the counterflow principle, in the cocurrent principle or in the crossflow principle.

In addition, however, it can also be advantageous if a supply line of air to the reformer is provided. In particular, air can be mixed with fuel upstream of the reformer. This makes it possible to optionally carry out a catalytic partial oxidation in addition to or as an alternative to steam reforming. This is particularly advantageous in a starting phase of the fuel cell system, in which a fuel cell stack is still cold and has to be heated. By supplying air during, in particular exclusively, a starting phase of the fuel cell system, the fuel cell stack can thus be warmed up by catalytic partial oxidation. If this has reached a predetermined temperature, the supply of air is switched off again, in particular by means of a valve. In addition, the air supply prevents or at least greatly reduces soot formation in the reformer or a superheater area of the heat exchanger during a starting phase of the fuel cell system in which the heat exchanger according to the invention can be arranged. It has been found that the supply of an oxygen-containing fluid such as air to the evaporation process of the water-fuel mixture prevents or at least greatly reduces soot formation during a, in particular exclusive, starting phase of a fuel cell system.

It is further advantageous if the afterburner is designed as part of the coated heat exchanger, with fuel cell stack exhaust gas flowing through a warm side of the heat exchanger. Thus, both the reformer and the afterburner are formed as part of the same heat exchanger, the reformer forming the cold side and the afterburner the warm side of the heat exchanger. The heat exchanger is preferably a plate heat exchanger. In the afterburner, fuel cell stack exhaust gas is completely burned downstream of the fuel cell stack. The warm side of the heat exchanger is also catalytically coated for this. The fuel which is not completely burned in the fuel cell stack is completely burned with the supply of cathode exhaust gas (air or oxygen-containing fluid). In order to accelerate this combustion, the afterburner, which forms the warm side of the heat exchanger, is coated to carry out a catalytic oxidation. Cathode exhaust gas and anode exhaust gas are brought together downstream of the fuel cell stack, in particular in the intermediate plate, in an exhaust line to form fuel cell stack exhaust gas. That means cathode exhaust gas and anode exhaust gas flow through the end plate separately from one another and are brought together in the intermediate plate, it being possible for only a part of the cathode exhaust gas and a part of the anode exhaust gas to be brought together. Remaining parts of the cathode exhaust gas and anode exhaust gas are used in respective partial exhaust gas lines. Merged fuel cell stack exhaust gas is guided in the exhaust gas line into the gas processing plate in which the afterburner is arranged. The fuel cell stack exhaust gas generally has a higher temperature, as a result of which heat can be transferred from the fuel cell stack exhaust gas to the fuel to be reformed in the reformer. The reformer is consequently coupled to the afterburner for heat transfer. The completely combusted fuel cell stack exhaust gas can advantageously also downstream of the afterburner

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Heating fuel can be used in an evaporator.

The fuel flows over the heat exchanger, which is designed as a plate, tube bundle heat exchanger or with an alternative structure, and heats up in the process. At the same time, the catalytic material is used to convert the fuel into a hydrogen-rich gas. Depending on the operating strategy, the conversion can be carried out endothermic, autothermal or exothermic. Steam reforming can take place through the water added to the fuel or through anode gas recirculation. In addition to the injection of the fuel to the anode line, an air supply is also provided for the conversion by means of catalytic partial oxidation. After the conversion of the fuel, the reformate gas thus created can be fed directly to the fuel cell stack. Alternatively, however, a further temperature adjustment can be carried out with or through the cathode gas. The heat required for steam reforming comes from the fuel cell stack exhaust gas, a mixture of anode and cathode exhaust gas. The oxidation takes place directly in the heat exchanger, since the warm side of the same is also catalytically coated (either directly or through an inserted mesh).

It is advantageous if the reformer has at least one, in particular two, fuel inlets for gaseous fuel. The reformer in particular has a U-shaped cross-sectional area, the two legs of the U-shaped reformer each having an inlet for gaseous fuel. This means that the anode supply line separates upstream of the reformer into two sub-lines, which each open into the reformer. Downstream of the reformer and in particular upstream of the intermediate plate, the two sub-lines are brought together again to form a common anode supply line, which is led indirectly to the anode section via the intermediate plate and the end plate. The reformed fuel is fed in the anode supply line through the intermediate plate and the end plate to the anode section of the fuel cell stack. For this purpose, the intermediate plate and the end plate each have one or more bushings for the reformed fuel. The cathode heat exchanger is advantageously arranged within the U-shaped reformer, so that the gas processing plate has a rectangular cross-sectional area. The cathode heat exchanger comprises at least one air inlet. Due to the design and arrangement of the heat exchanger and the cathode heat exchanger according to the invention, the gas processing plate itself is compact and small, heat-transfer surfaces nevertheless being large, so that high heat transfer can take place.

It is advantageous if a starting burner is provided. Basically, this can be formed as part of the gas processing plate. However, it is expedient if it is arranged at least partially outside the gas processing plate, for example as a separate plate. The starting burner is preferably designed as a two-stage burner, a first region of the starting burner being arranged outside the gas processing plate and comprising a catalytic material. Air and fuel are fed to the first area of the starting burner, the fuel being catalytically burned by the air. In order to protect the catalytic material, the combustion is advantageously carried out incompletely.

For this purpose, it is advantageous if a warm side of the cathode heat exchanger is designed as a second region of the starter burner, fuel being able to be supplied between a first region and the second region of the starter burner. Downstream of the starting burner, the incompletely burned fuel is supplied to the cathode heat exchanger arranged in the gas processing plate. It can be provided that a feed line for fuel is fed downstream of the first region of the starting burner and upstream of the cathode heat exchanger. This is advantageous in order to heat an air passed over a cold side of the cathode heat exchanger to a high temperature. The lines from the first area of the star burner lead over a warm side of the cathode heat exchanger forming the second area of the starter burner. In order to burn the fuel supplied downstream of the cathode heat exchanger, the warm side of the cathode heat exchanger is coated catalytically, whereas the cold side of the cathode heat exchanger is not coated. On the cold side of the cathode heat exchanger is in particular by a

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AT 521 064 B1 2020-03-15 Austrian patent office, a fan located outside the gas processing plate heats the oxygen-containing fluid and subsequently guides it through the intermediate plate and end plate in the direction of the cathode section. For this purpose, the blower is arranged downstream of the air source and upstream of the cathode heat exchanger. Downstream of the cathode heat exchanger, the still warm gas can be fed to the evaporator, so that both the exhaust gas from the starting burner and the fuel cell exhaust gas can be used to evaporate the fuel.

Consequently, a heat exchanger, the cathode heat exchanger, is also used on the cathode line, but is only coated on the exhaust gas side. The cathode air heated with the aid of the cathode exhaust gas can thus be fed directly to the fuel cell stack. How much cathode exhaust gas flows to the anode line for the oxidation of the anode gas and how much flows to the cathode line is regulated in particular via external throttle valves in the exhaust line. If the cathode air is too hot, it can be cooled by means of the supply line of air which is directed past the cathode heat exchanger. The mixing takes place as described above in the intermediate plate, in particular immediately before entering the fuel cell stack or, if the end plate and the intermediate plate are combined, directly in the end plate of the fuel cell stack. If more energy is required to heat the air in the cathode line, the external start burner can be used to heat the fuel or to inject fuel onto the exhaust side of the cathode heat exchanger in order to oxidize there with the cathode exhaust gas.

It is expedient if an evaporator is provided. This is particularly advantageous if a liquid fuel is used. The evaporator is arranged, in particular, outside the gas processing plate in the anode feed line upstream of the reformer. Liquid fuel is supplied to the evaporator, which is designed in particular as the cold side of a heat exchanger. The liquid fuel is evaporated in the reformer via the fuel cell stack exhaust gas and / or starting burner exhaust gas which is conducted over the warm side of the heat exchanger. The corresponding exhaust pipes are therefore connected to the liquid fuel in a heat-transferring manner. If the fuel cell system according to the invention is operated with gaseous fuel such as gaseous natural gas, an arrangement of the evaporator is not necessary; there is no need for the evaporator.

It is advantageous if the end plate and the intermediate plate are designed as an integral element. It is particularly expedient if the integral plate-shaped element formed in this way is designed and arranged as a region or part of the fuel cell stack itself. This further increases the compactness of the fuel cell system. Since the intermediate plate is thus formed as part of the fuel cell stack, the line section and passages for the operating fluids and lines are also part of the fuel cell stack. With such a design, the gas processing plate can consequently be connected directly to the fuel cell stack.

If two fuel cell stacks are provided, a mirror-inverted arrangement of the intermediate plate and the end plate is provided below the gas processing plate, the second fuel cell stack directly adjoining the second end plate. When using two or more fuel cell stacks, it may be advantageous if the gas processing plate has a correspondingly large thickness.

Basically, the gas processing plate is constructed in such a way that one, two or more fuel cell stacks can in particular be connected directly to it. The intermediate plate is designed as a thin intermediate plate or is connected directly to the fuel cell stack via the end plate.

It is advantageous if an air source and a fuel source are provided, with oxygen-containing fluid being able to be conveyed in the direction of a cathode heat exchanger by a blower arranged in a cathode supply line. Both sources and the blower are advantageously arranged outside the gas processing plate.

At least one anode supply line is advantageously provided, with the

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Anode supply line fuel downstream of the fuel source in the direction of the evaporator, downstream of the evaporator in the direction of the gas processing plate, downstream of the gas processing plate in the direction of the intermediate plate and the end plate and downstream of the end plate as evaporated and reformed fuel can be supplied to the anode section. To convey the fuel, a conveying device such as a pump is advantageously arranged downstream of the fuel source. In particular, it is further provided that a starting burner supply line branches off from the anode supply line downstream of the delivery device and upstream of the evaporator in order to supply fuel to the starting burner. Metering devices, in particular valves, are provided in the pipes downstream of the branch for metering the fuel in the lines. A supply of fuel can also be completely stopped by the metering devices. The metering devices are in particular arranged outside the gas processing plate in a so-called cold box.

It is useful if at least one exhaust gas line is provided downstream of the fuel cell stack, in particular in the intermediate plate, in which anode exhaust gas and cathode exhaust gas can be combined to form fuel cell stack exhaust gas, the fuel cell stack exhaust gas downstream of the fuel cell stack and the end plate through the intermediate plate in the direction of the afterburner and downstream of the Afterburner can be guided in the direction of the evaporator. The exhaust gas line, in which cathode exhaust gas and anode exhaust gas are brought together, is consequently arranged in the intermediate plate. The anode exhaust gas and the cathode exhaust gas flow through the end plate separately from one another, which includes passages for guiding the two exhaust gas flows. For example, the end plate can comprise a passage for cathode exhaust gas and two passages for anode exhaust gas.

It is also advantageous if at least one cathode supply line is provided, with oxygen-containing fluid being able to be supplied to the cathode section downstream of the air source in the direction of the cathode heat exchanger and downstream of the cathode heat exchanger via the cathode supply line. To convey the air, a conveying device, in particular a blower, is provided downstream of the air source, which is arranged outside the gas processing plate. In particular, it is further provided that a plurality of partial lines branch off from the cathode supply line downstream of the conveying device and upstream of the cathode heat exchanger. For example, a first partial line for supplying air downstream of the evaporator is provided, so that a partial oxidation reaction can be carried out in the reformer. The first sub-line leads into the gas processing plate. In addition, a second sub-line is provided, which is designed as a supply line of oxygen-containing fluid and via which air downstream of the cathode heat exchanger can be fed back to the cathode supply line. This second sub-line, which is designed as a feed line, separates from the cathode feed line outside the gas processing plate and leads directly into the intermediate plate without passing through the gas processing plate. The second sub-line is thus designed as a bypass line of the cathode heat exchanger and the gas processing plate. A third sub-line is also provided, which conveys air to the starting burner. Dosing devices, in particular valves, are provided in the lines downstream of the branches for metering the air in the lines. A supply of air can be regulated or even set entirely by the metering devices. The metering devices are again arranged outside the gas processing plate in the cold box.

In the context of the invention, a cold box is to be understood as a unit in which a lower temperature than in the hot box is necessary. In particular, valves, blowers, sensors or the like are arranged in the cold box. The cold box is thermally separated from the hot box.

In an embodiment variant of the invention it is provided that an anode recirculation line is provided. Part of this is arranged in the intermediate plate, in which the anode recirculation line separates from the anode exhaust gas line. Downstream of this partition, the anode recirculation line exits the intermediate plate because an anode exhaust gas conveyor, such as a blower for conveying a part, is located outside the plates

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AT 521 064 B1 2020-03-15 Austrian patent office of anode exhaust gas is arranged in the direction of the reformer. Downstream of the fan, the anode recirculation line leads in the direction of the gas processing plate, where anode exhaust gas is fed to the reformer, in order to provide water which may be necessary for the reforming. This variant is particularly advantageous when using diesel as fuel. The division of the anode exhaust gas for recirculation and for oxidation takes place via a recirculation blower or with the aid of a jet pump, by means of which a distribution ratio to a fixed value can be determined and controlled. The channels are divided in the intermediate plate or, in the case of a combination with the end plate, directly in the end plate of the fuel cell stack.

It when the gas processing plate is at least partially made additive is particularly advantageous. In particular, the gas processing plate is produced by 3-D printing. It can be provided that elements of the same are printed individually or the gas processing plate is printed as a whole unit. The use of additive manufacturing (3-D printing) increases the performance of the fuel cell system, since the compact design and optimization of the structure reduce or avoid pressure losses in the system. In particular, the entire gas processing plate or all elements provided in it are manufactured additively.

A fuel cell system according to the invention is advantageously used to provide electrical energy in a motor vehicle.

Further advantages, features and effects result from the exemplary embodiments presented below. In the drawings, to which reference is made, show:

[0040] FIG. 1 shows an exploded view of a fuel cell system according to the invention;

[0041] FIG. 2 shows an exploded view of a further fuel cell system according to the invention;

3 shows a block diagram to illustrate a fuel cell system according to the invention according to FIG. 2.

1 shows a fuel cell system 1 according to the invention, which is an SOFC system. This includes a fuel cell stack 2 (not shown in FIG. 1) with a cathode section 3 and an anode section 4. Furthermore, the fuel cell system 1 comprises an end plate 5, an intermediate plate 6 and a gas processing plate 7. The plates 5, 6, 7 and the fuel cell stack 2 are one above the other stacked to each other.

The gas processing plate 7 comprises a U-shaped heat exchanger 16 which is arranged in an anode line or anode supply line 25. The heat exchanger 16 has a cold and a warm side, the cold side being a reformer 13 and the warm side being an afterburner 14. Both sides are coated catalytically. The heat exchanger 16 is flowed through in the exemplary embodiment according to FIG. 1 in the countercurrent principle, gaseous fuel to be reformed being heated in the reformer 13 by fuel cell stack exhaust gas, which is completely burned in the afterburner 14, and reformed by the catalytic material. The fuel cell exhaust gas is guided in an exhaust gas line 26, in which a cathode exhaust gas line 26a and an anode exhaust gas line 26b are brought together. The reformer 13 also has two fuel inlets 17, via which fuel can be introduced indirectly into the reformer 13 from a fuel source 23, not shown.

A cathode heat exchanger 15 is arranged between the legs of the U-shaped heat exchanger 16. The cathode heat exchanger 15 also has a cold and a warm side. An oxygen-containing fluid, in particular air, can be introduced via an air inlet, via a cathode supply line 23, from an air source 22 (not shown in FIG. 1) into a cold side of the cathode heat exchanger 15. The cold side of the cathode heat exchanger 15 is not coated. The air flowing downstream of the cathode heat exchanger

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AT 521 064 B1 2020-03-15 Austrian patent office is supplied to the cathode section 3, is heated via cathode exhaust gas, which is conducted via the cathode exhaust gas line 26a into a warm side of the cathode heat exchanger 15. Since fuel which is not completely burned can be fed to the cathode heat exchanger 15 downstream of the cathode section 3 via an outlet line of a starting burner 18, the warm side of the same is catalytically coated.

The heat exchanger 16 and the cathode heat exchanger 15 are designed as plate heat exchangers, both of which are flowed through in the counterflow principle. The air inlet of the cathode heat exchanger 15 is arranged on an opposite side of the fuel inlets 17 of the heat exchanger 16.

The intermediate plate 6 is designed as a thin distributor plate, in which gas streams are distributed, brought together and / or added. The intermediate plate 6 each comprises a passage 10a for air and a passage 11a for fuel. Via these passages 10a, 11a, which are in flow connection with the cathode heat exchanger 15 via the cathode supply line 24 or with the reformer 13 via the anode supply line 25, air is indirectly via the end plate 5 in the direction of the cathode section 3 and fuel is indirectly via the end plate in the direction of Anode section 4 out. The intermediate plate further comprises an air supply line 12 for regulating and / or adjusting a temperature of the heated air carried in the cathode supply line 24. In addition, further passages 10b, 11b for air and fuel are provided in the intermediate plate. As shown in FIG. 1, one passage for air 10b and two passages for fuel 11b are provided. The cathode exhaust line 24 leads from the cathode section 3 indirectly via the end plate 5 through the passage for air 10b to the reformer 13 and to the cathode heat exchanger 15 in the gas distribution plate 7. The anode exhaust line 25 leads indirectly via the end plate 5 to the reformer 13.

For the indirect routing of the cathode supply line 24 and the anode supply line 25 in the direction of the fuel cell stack section 2 and the removal of the fuel cell stack section 2 of the cathode exhaust gas in the cathode exhaust line 26a and the anode exhaust gas in the anode exhaust line 26b, the end plate has a plurality of passages 8a, 8b, 9a, 9b. A passage 8s for connecting the cathode supply line 24 to the cathode section 3 and a passage 9a for connecting the anode supply line 25 to the anode section 4 are provided. Two passages 9b for discharging anode exhaust gas and one passage 8b for discharging cathode exhaust gas are also provided.

A further exemplary embodiment of a fuel cell system 1 according to the invention is shown in FIG. 2. This corresponds in many parts to the fuel cell system 1 according to FIG. 1, which is why a new description of the components and functions which correspond to those of FIG. 1 is dispensed with. In contrast to the fuel cell system 1 according to FIG. 1, the fuel cell system 1 shown in FIG. 2 comprises an anode recirculation line 28. This is partially arranged in the intermediate plate 4, in which the anode recirculation line 28 separates from the anode exhaust line 26b. Downstream of this separation, the anode recirculation line 28 emerges from the intermediate plate 4, since a fan 30 for conveying a part of anode exhaust gas in the direction of the reformer 13 is arranged outside the plates. Downstream of the blower 30, the anode recirculation line 28 leads in the direction of the gas processing plate 7, where anode exhaust gas is fed to the reformer 13, in order to provide water which may be necessary for the reforming.

The division of the anode exhaust gas for recirculation and for oxidation takes place via a recirculation fan 30.

FIG. 3 shows a block diagram to illustrate a fuel cell system according to the invention according to FIG. 2. In addition to the functions and elements already described, it is also shown here that fuel cell stack exhaust gas, which is completely combusted, and emits all of the heat to components arranged in the gas processing plate 7 is released to the environment 31. A start burner 18 and an evaporator 21 are also provided. The star burner 18 and the evaporator 21 are advantageously outside the gas

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AT 521 064 B1 2020-03-15 Austrian patent office processing plate 7 and the intermediate plate 6 arranged. Furthermore, various sub-lines of the cathode supply line 24 and the anode supply line 25 are shown, wherein an amount of air and fuel conveyed therein can be regulated via valves 33. A fuel pump 32 is provided for conveying the fuel in the direction of the gas processing plate 7.

The inventive design of the fuel cell system 1 enables a functional integration of the gas processing plate 7 into flow channels by means of heat-exchanging components and catalytic coatings. Structural optimization is also carried out by means of additive manufacturing of the gas processing plate 7.

The fuel is supplied to the anode line in the anode supply line 25 of the gas processing plate 7 consisting of the heat exchanger 16 in gaseous and superheated form. The fuel flows over the heat exchanger 16 and heats up in the process. At the same time, the conversion of the fuel to a hydrogen-rich gas is carried out by the catalytic coating used. Depending on the operating strategy, the conversion can be endothermic, autothermal or exothermic. Steam reforming can take place through the water added to the fuel or through the anode gas recirculation. In addition to the injection of the fuel to the anode line, an air supply is also provided for the conversion by means of catalytic partial oxidation. After the conversion of the fuel, the reformate gas can be fed directly to the fuel cell stack 2 or a further temperature adjustment can be carried out with the cathode gas. The heat required for steam reforming comes from the exhaust gas fuel cell stack 2, which is a mixture of anode and cathode exhaust gas. The oxidation takes place directly in the heat exchanger 16, since a catalytic coating is also provided here.

The division of the anode exhaust gas for recirculation and for oxidation takes place via the recirculation fan 30, which defines the distribution ratio. The channels are divided in the intermediate plate 6 or, in the case of a combination with the end plate 5, directly in the end plate 5 of the fuel cell stack 2.

A heat exchanger, the cathode heat exchanger 15, is also used on the cathode line, but is only coated on the exhaust side. The cathode air heated with the aid of the cathode exhaust gas can thus be fed directly to the fuel cell stack 2. How much cathode exhaust gas flows to the anode line for the oxidation of the anode gas and how much flows to the cathode line is regulated via external throttle valves in the exhaust line. If the cathode air is too hot, it can be cooled by means of the supply line 12 for air, which is led past the cathode heat exchanger 15. The mixing takes place in the intermediate plate 6, directly before entering the fuel cell stack 2 or, in combination, directly in the end plate 5 of the fuel cell stack 2. If more energy is required to heat the cathode line, the externally arranged starting burner 18 can be used to heat or fuel be injected onto the exhaust gas side of the cathode heat exchanger 15 in order to oxidize there with the cathode exhaust gas.

The exhaust gas from the cathode and anode lines can be used to evaporate the fuel after leaving the cathode heat exchanger 15, the evaporator 21. The evaporator 21 can sit externally or can be fully integrated in the gas processing plate.

The external start burner 18 is a catalytic burner to which air and fuel are supplied. This has two stages or, based on the oxidative catalytic coating already present on the exhaust gas side of the heat exchanger, components can be carried out in one stage with a further injection / supply into the starting burner exhaust gas.

In order to bring the fuel cell system 1 to operating temperature, the start burner 18 heats it up. The starting burner exhaust gas flows into the intermediate plate 6 or to the end plate 5 combined with the intermediate plate 6, where it mixes in the cathode outlet with the cathode exhaust gas of the fuel cell stack 2 and flows together over the exhaust gas side of the anode and cathode lines. As soon as the "light-off" temperatures of the catalytic Be

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Stratifications are reached, fuel can flow over the anode line. Through partial oxidation, the fuel cell stack 2 can now also be flowed through with hot protective gas, thereby accelerating the heating process and at the same time protecting the anode from oxidation.

In summary, the system architecture of the fuel cell system 1 according to the invention has the following advantages:

- Functional integration to save on components: both space and material are saved, as a result of which a heating-up time is also reduced;

- Higher efficiency in heat transfer through the large areas and direct coating of the heat exchanger 16 and the cathode heat exchanger 15;

- By using additive manufacturing (3-D printing) a further increase in performance is achieved by the compact design. In addition, the structural optimization leads to a low pressure loss;

- Due to the compact arrangement of the gas processing plate 7 and the fuel cell stack, less complex heat insulation is possible by means of a box design.

Claims (20)

Claims 1. Fuel cell system (1), in particular an SOFC system, the fuel cell system (1) being constructed in a stack-like manner, comprising at least one fuel cell stack (2) with a cathode section (3) and an anode section (4), at least one end plate (5) and at least one gas processing plate (7), the fuel cell stack (2) being arranged at least in regions above the end plate (5), characterized in that at least one intermediate plate (6) is provided, the intermediate plate (6) at least in regions above the gas processing plate (7 ) and the end plate (5) is arranged at least in regions above the intermediate plate (6). 2. Fuel cell system (1) according to claim 1, characterized in that the fuel cell stack (2), the end plate (5), the intermediate plate (6) and the gas processing plate (7) are in particular non-positively connected to one another. 3. Fuel cell system (1) according to claim 1 or 2, characterized in that the gas processing plate (7) and the intermediate plate (6) have the same or approximately the same cross-sectional area. 4. Fuel cell system (1) according to one of claims 1 to 3, characterized in that the end plate (5) has at least a first passage (8a) for an oxygen-containing fluid and a second passage (9a) for reformed fuel, the end plate ( 5) is designed in particular as an integral element of the fuel cell stack (2). 5. Fuel cell system (1) according to one of claims 1 to 4, characterized in that the intermediate plate (6) has at least a first passage (10) for an oxygen-containing fluid, a second passage (11) for reformed fuel and a feed line (12 ) of a further oxygen-containing fluid. 6. Fuel cell system (1) according to one of claims 1 to 5, characterized in that the gas processing plate (7) comprises a reformer (13), an afterburner (14) and at least one cathode heat exchanger (15), the gas processing plate (7) Hotbox forms. 7. The fuel cell system (1) according to claim 6, characterized in that the reformer (13) is designed as part of a coated heat exchanger (16), a fuel to be reformed flowing through a cold side of the heat exchanger (16). 8. The fuel cell system (1) according to claim 7, characterized in that the afterburner (14) is designed as part of the coated heat exchanger (16), fuel cell stack exhaust gas flowing through a warm side of the heat exchanger (16). 9. Fuel cell system (1) according to one of claims 6 to 8, characterized in that the reformer (13) has at least one, in particular two, fuel inlet (17) for gaseous fuel. 10. Fuel cell system (1) according to one of claims 1 to 9, characterized in that a starting burner (18) is provided. 11. The fuel cell system (1) according to claim 10, characterized in that a warm side of the cathode heat exchanger (15) is designed as a second region (19) of the starter burner (18), between a first region and the second region (19) of the starter burner (18) Fuel can be supplied. 12. Fuel cell system (1) according to one of claims 1 to 11, characterized in that an evaporator (21) is provided. 13. Fuel cell system (1) according to one of claims 1 to 12, characterized in that the end plate (5) and the intermediate plate (6) are formed as an integral element. 12/16 AT 521 064 B1 2020-03-15 Austrian patent office 14. Fuel cell system (1) according to one of claims 1 to 13, characterized in that an air source (22) and a fuel source (23) are provided, wherein oxygen-containing fluid from a in a cathode supply line (24) arranged blower (20) in the direction a cathode heat exchanger (15) can be promoted. 15. The fuel cell system (1) according to claim 14, characterized in that at least one anode supply line (25) is provided, wherein fuel downstream of the fuel source (23) in the direction of the evaporator (21), downstream of the evaporator (21) via the anode supply line (25) ) in the direction of the gas processing plate (7), downstream of the gas processing plate (7) in the direction of the intermediate plate (6) and the end plate (5) and downstream of the end plate (5) as evaporated and reformed fuel can be fed to the anode section (4). 16. The fuel cell system (1) according to claim 15, characterized in that at least one exhaust gas line (26) is provided downstream of the fuel cell stack (2), in particular in the intermediate plate (6), wherein anode exhaust gas and cathode exhaust gas can be combined to form fuel cell stack exhaust gas, the fuel cell stack exhaust gas downstream of the fuel cell stack (2) and the end plate (5) through the intermediate plate (6) in the direction of the afterburner (14) and downstream of the afterburner (14) in the direction of the evaporator (21). 17. Fuel cell system (1) according to one of claims 14 to 16, characterized in that at least one cathode supply line (24) is provided, wherein via the cathode supply line (24) oxygen-containing fluid downstream of the air source (22) in the direction of the cathode heat exchanger and downstream of the cathode heat exchanger (15) can be fed to the cathode section (3). 18. Fuel cell system (1) according to one of claims 1 to 17, characterized in that an anode recirculation line (28) is provided. 19. Fuel cell system (1) according to one of claims 1 to 18, characterized in that the gas processing plate (7) is at least partially made additively. 20. Use of a fuel cell system (1) according to one of claims 1 to 19 for providing electrical energy in a motor vehicle.