JP2022547518A - Burner for fuel cell system - Google Patents

Abstract

The invention relates to a burner (1) for a fuel cell system (100), in particular for an SOFC system, the burner (1) being configured and arranged as a start burner and/or an afterburner, arranged one behind the other. comprising two reaction chambers (2, 3), the second reaction chamber (3) indirectly following the first reaction chamber (2) in flow direction, the reaction chambers (2, 3) each containing catalyst material provided with an evaporator (4), the evaporator (4) being arranged between the respective reaction chambers (2,3). Furthermore, the invention relates to a fuel cell system (100) comprising such a burner (1). Additionally, the present invention relates to a method of operating a fuel cell system (100) with a burner (1).
[Selection drawing] Fig. 1

Description

The present invention relates to a burner for a fuel cell system, in particular for an SOFC system, the burner being configured and arranged as a start burner and/or an afterburner and comprising two reaction chambers arranged one behind the other and having a flow direction A second reaction chamber indirectly follows the first reaction chamber in, each of these reaction chambers containing catalyst material.

Further, the invention relates to the use of such burners.

Furthermore, the invention relates to a fuel cell system with such a burner.

Additionally, the present invention relates to a method of operating a fuel cell system.

Burners for fuel cell systems are known from the prior art. Especially in SOFC systems that operate on liquid fuels such as diesel or ethanol or mixtures of ethanol and water, it may be necessary to vaporize and reform the liquid fuel in a first step. Due to the high moisture content (approximately 55%), it is difficult and impossible to burn the fuel in a flame burner, which is applied, for example, in diesel-powered fuel cell systems, especially when moist ethanol is used. up to.

Furthermore, it is necessary to heat the fuel cell system to operating temperature during a cold start, for which purpose so-called start burners are usually provided. In addition to this, an afterburner is also usually required to completely combust the exhaust gases from the anode section. Known fuel cell systems are therefore often provided with a start burner and an afterburner.

A start burner is generally understood to be a start burner for heating the afterburner of the fuel cell system, which in turn is provided for heating the reformer of the fuel cell system. The afterburner can be preheated by the start burner at cold start of the fuel cell system when the afterburner is still cold and therefore not suitable for heating the reformer of the fuel cell system. As soon as the afterburners reach operating temperature due to operation of the fuel cell system, the start burners can be deactivated.

For example, DE 102 37 744 A1 discloses a fuel cell system with a starter burner integrated in the burner housing.

Furthermore, from DE 10 2006 048 984 A1 the use of a burner device in a fuel cell system is known. This burner device can be operated as an afterburner and a start burner. However, it is not clear from this document how fuel cell systems, especially those operating on liquid fuels, can be efficiently brought to operating temperature.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the efficiency of a burner of the type mentioned at the outset, with which a fuel cell system can be brought to operating temperature quickly and efficiently.

Furthermore, it is an object to provide a fuel cell system with such a burner.

A further object is to provide an improved method of operating a fuel cell system.

According to the invention, this task is achieved in a burner of the initially mentioned type by providing an evaporator which is arranged between the respective reaction chambers.

The advantages associated therewith can be seen, inter alia, in that the heat transfer functions particularly effectively with the configuration of the burner according to the invention. A burner configured in this way can be configured and arranged both as a start burner and as an afterburner or can be configured and arranged. That is, depending on the operating state of the fuel cell system in which the burners are arranged, only one component functions simultaneously as a start burner and as an afterburner. The burner is configured as a multi-stage burner, the first reaction chamber forming the first stage, the second reaction chamber forming the second stage, and the evaporator forming the further stage. The fuel is vaporized and at least partially reformed in the burner according to the invention on the one hand and completely combusted and heated to the required or predefined temperature on the other hand. The process gas exiting the burner has a sufficiently high temperature to heat several parts of the fuel cell system due to its multi-stage embodiment. Furthermore, the burner allows complete post-combustion of the fuel cell exhaust gas from the anode and cathode sections of the fuel cell stack, thus eliminating the need for separate afterburners. This is because the burner can be used as a start burner and an afterburner in a single fuel cell system. Both reaction chambers are successively flowed through by a mixture consisting of air and a mixture of fuel and water or by fuel cell exhaust gases. That is, the second reaction chamber is arranged downstream of the first reaction chamber and the evaporator is arranged between them. That is, they are arranged so that they follow one another in the direction of flow.

According to the invention, an evaporator is provided, which is arranged between the two reaction chambers by design. This means that the evaporator is arranged in particular immediately after the first reaction chamber, in particular immediately before the second reaction chamber. The hot side of the evaporator is arranged between the respective reaction chambers in the direction of flow. The evaporator is constructed and arranged to heat the liquid fuel to bring it to a gaseous state. For example, fuel enters the cold side of the vaporization chamber at approximately 25°C and leaves it as a gas at approximately 800°C. Downstream of the cold side of the evaporation chamber, gaseous fuel is then led into the first reaction chamber. In addition, an oxygen-containing gaseous fluid, in particular air, is also guided into the first reaction chamber, and the gaseous fuel and air are mixed with one another, in particular directly upstream of the first reaction chamber. .

SUMMARY OF THE INVENTION In a first aspect of the present invention, a burner for a fuel cell system, in particular for an SOFC system (SOFC stands for "solid oxide fuel cell") is provided. Such types of fuel cell systems can, for example, operate on liquid fuels.

Air is understood within the framework of the present invention to be an oxygen-containing fluid, especially gaseous. In particular, air is understood to be ambient air. The fuel is a power source which is preferably a mixture of liquid fuel and water, especially a mixture of ethanol and water.

The burner is configured in particular for the catalytic combustion of liquid fuels, for which both reaction chambers each contain catalytic material. The burner concept is based on fuel vaporization and partial pre-reformation, in particular mixtures of ethanol and water as fuel, which are known to be difficult to vaporize and subsequently burn due to their high water content. make it possible to use. It is thereby possible to utilize fuels with high moisture content, which are not suitable for evaporative reforming without the necessary recirculation on the anode side, also for the starting process. However, once the burner according to the invention is placed in a fuel cell system, it can easily be operated with liquid fuel and water mixtures, such as ethanol and water mixtures.

Advantageously, the evaporation device includes two evaporation chambers. At this time, the second evaporation chamber is preferably arranged downstream of the first evaporation chamber. Both vaporization chambers are preferably arranged and configured for heat absorption, the first vaporization chamber absorbing heat from the first reaction chamber and the second vaporization chamber from the first vaporization chamber. absorb heat. This takes place through the hot side of the respective evaporation chamber or on the hot side, respectively. Advantageously, separate regulators for separate fuel supplies are provided for each evaporation chamber. Preferably, the regulating device is constructed as an injector or a valve and is provided upstream of another evaporator arranged upstream of the evaporator. Via the first vaporization chamber, the fuel can be vaporized through the cold side (by heat from the first reaction chamber) and through the hot side the at least partially combusted fuel-air mixture is transferred to the second vaporizer. can be guided to the evaporation chamber of the Correspondingly, the fuel is guided via the second vaporization chamber to the cold side of the second vaporization chamber through a second control device, which is also configured as an injector and/or a valve, where it evaporates and is subsequently vaporized. 2 reaction chamber. Likewise, the at least partially combusted fuel-air mixture can be directed further into the second reaction chamber for complete combustion. The first evaporation chamber is then arranged in particular downstream of the chamber outlet of the first reaction chamber and the second evaporation chamber is arranged upstream of the chamber inlet of the second reaction chamber. Both evaporation chambers are in particular directly adjacent to each other.

A mixing zone is preferably provided upstream of the first reaction chamber, the mixing zone being arranged in particular in the vicinity of the chamber inlet of the first reaction chamber. The mixing zone is therefore preferably arranged in particular immediately upstream of the first reaction chamber and configured for mixing air and gaseous fuel during the fuel cell system start-up process. The resulting fuel-air mixture is subsequently guided to the first reaction chamber and is at least partially combusted there. During on-going or rated operation, the mixing chamber normally has no special function. This is because in such operating conditions the burner operates as an afterburner, where the fuel cell stack exhaust gas is combusted. In principle, it is then advantageous for this purpose if the anode exhaust gas is already mixed with the cathode exhaust gas (air) upstream in the mixing chamber. However, it may also be intended that this takes place within the mixing chamber. What is important is that the mixture of fuel and air enter the first reaction chamber. The mixing zone may be configured as part of the first reaction chamber or may be combined therewith.

It can be expedient if the reaction chamber and the evaporator are each constructed at least in a section rotationally symmetrical and they each comprise at least two, in particular cylindrical layers. It is particularly preferred that the reaction chamber and the evaporation chamber are each at least partially hollow-cylindrical. The cylindrical layers are then, in particular, inserted coaxially into one another or arranged coaxially with one another. Thereby, a chamber can be formed between each cylindrical layer.

A separate evaporator is advantageously provided for the start-up and/or heating operation of the burner, which is arranged upstream of the evaporator. A separate evaporator is required during a cold start of the fuel cell system, especially the burner. Because the evaporator is not yet hot, no heat is provided there to evaporate the fuel. A separate evaporator usually includes a heating device to reach the required temperature for vaporization of the fuel. Thus, at cold start the evaporator is initially non-functional. The further evaporator preferably also has a reforming unit, whereby the fuel not only evaporates upon heating, but is at least partially reformed. This results in a fuel temperature of approximately 600° C. when exiting the separate evaporator.

It is then expedient if the separate evaporator contains an electrical heating device. Thus, the fuel is vaporized by an electric heating device and can have a temperature of approximately 600° C. downstream of a further vaporizer. As soon as the burners reach the required operating temperature and thus generate sufficient heat in the first reaction chamber for the first evaporation chamber, the electric heating device can be switched off. This takes place in particular already when ignition takes place in the first reaction chamber. The fuel then evaporates in the evaporator, rendering the other evaporators ineffective. The burner can be preheated during the starting phase, ie when the burner is cold started, by means of an electric heating device. In particular, the electric heating device is designed for heating the fuel, the electric heating device being only for heating, vaporizing and/or reforming the fuel in the heating phase of the burner serving as start burner. is particularly preferred. Thus, the power source, which may exist as a fuel or a mixture of fuel and water, can not only be preheated, but also vaporized and pre-reformed to some preset extent. This allows the burner to operate particularly efficiently when used as a start burner. During the heating operation, the electrical heating device may operate for a period of time of, for example, approximately 2 to 10 minutes. After the electrical heating device has been switched off, fuel is led through the first injector in the direction of the first evaporation chamber until the rated operating point of the fuel cell system is reached. Fuel is then vaporized in the first vaporization chamber by the heat generated during the exothermic reaction in the first reaction chamber. When burners are used as afterburners, electrical heating devices are usually not used. Electrical assistance for evaporation and reforming can in principle be carried out with external components, but for reasons of space the integration of such functions should be encouraged.

A first fuel supply line is preferably provided, via which fuel is fed through a further evaporator and evaporator, in particular through the first vaporization chamber, to the mixing zone and subsequently to the first 1 reaction chamber. A fuel supply line is configured to draw a first working fluid in the form of fuel into the burner or into the first reaction chamber. In particular a first injector and/or a first valve are arranged upstream of the first fuel supply line. Via the injector, the fuel can be guided into the first fuel supply line, especially during the starting operation, ie when the burner is used as the starting burner. As soon as the burner and fuel cell system reach the rated operating point, the first regulator closes so that no more fuel is supplied and the burner is used only as an afterburner. At the same time, the evaporation chamber also becomes non-functional at rated operation. That is, the first fuel supply line extends, in particular, from the fuel source via the further evaporator, the evaporator to the mixing zone and the first reaction chamber and/or interconnects these members.

More preferably, an air supply line is provided, via which air can be guided to the mixing area and subsequently to the first reaction chamber. The mixing region is constructed and arranged to mix fuel and air. That is, air and fuel meet in the mixing chamber when the burner is used as a start burner. When a burner is used as an afterburner, especially in rated operation, it is preferred that only the fuel cell stack exhaust gas, which already contains in particular cathode and anode exhaust gas, is directed to the burner. However, it may also be provided that air is additionally guided to the first reaction chamber via an air supply line and/or fuel via a first fuel supply line. The air supply line thus runs in particular from the air source via the mixing area to the first reaction chamber.

A second fuel supply line may advantageously be provided, via which fuel can be guided through the second vaporization chamber to the second reaction chamber. An injector, which can be opened and closed for guiding the fuel, is also preferably arranged upstream of the second fuel supply line. During the start-up phase of the burner, fuel can be guided via a second fuel supply line from a second injector or a second valve directly into the second vaporization chamber and out of the first vaporization chamber. The heat of the incoming at least partially combusted fuel-air mixture can vaporize this fuel. Downstream of the second vaporization chamber is a second reaction chamber which is brought to operating temperature by vaporized fuel during the start-up phase of the burner. During nominal operation, the second regulator is also normally switched off, so that fuel is no longer guided through the second fuel supply line.

A system exhaust gas line is preferably provided, via which the system exhaust gas can be guided through the mixing area to the burner. The system exhaust is specifically the fuel cell stack exhaust where the anode and cathode exhaust are mixed just downstream of the fuel cell stack. This line is specifically used only during rated operation and connects at least one fuel cell stack with the burner. When the burner assumes the afterburner function, the anode or fuel cell exhaust gas (anode exhaust gas and cathode exhaust gas) flows in the system exhaust gas line and is supplied to the burner for complete combustion. Since the cathode exhaust gas is in particular air only, the anode exhaust gas is combusted together with the cathode exhaust gas in a burner. In case the temperature is too high when the burner is operated as afterburner, it may be expedient to additionally supply air to the burner via the air supply line. At this time, nothing normally flows through the first fuel supply line and the second fuel supply line, that is, they are not operating. Within the framework of the present invention, system exhaust gas is understood to be stack exhaust gas.

The use of the burners according to the invention is preferably carried out as start burners and afterburners in fuel cell systems operating on liquid fuels.

In another aspect of the invention, there is provided a fuel cell system having a burner as detailed above. The fuel cell system further includes a fuel cell stack with an anode section and a cathode section, a reformer, and a heat exchanger, with burners for heating the reformer and drawn from the cathode section. It is arranged and configured for heating at least one heat exchanger responsible for heating the air to be heated. Accordingly, the fuel cell system according to the invention offers the same advantages as those described in detail with respect to the burner according to the invention.

Preferably, the fuel cell system is an SOFC system. The reformer is preferably arranged for reforming a fuel mixture, for example ethanol and water, into another fuel mixture, in this case hydrogen and carbon dioxide. The reformed hydrogen can be utilized for electric current generation in the fuel cell stack. A burner is configured to heat the reformer with the fuel cell exhaust gas from the fuel cell stack.

In a preferred development of the invention, a separate heat exchanger can be provided, the process gas leaving the burner flowing via the hot side of the heat exchanger and the fuel via the cold side of the heat exchanger. It heats the air flowing to the cathode area of the cell stack. The fuel cell system according to the invention finds particular application in motor vehicles.

A further object is achieved when a method of the kind mentioned at the outset comprises the following steps.
- the electrical heating device is activated, the fuel is introduced via the first adjusting device into the first fuel supply line, and the fuel is guided via the first fuel supply line to the further evaporator; to at least evaporate the fuel,
- air is introduced into the mixing zone upstream of the first reaction chamber via an air supply line,
- fuel is guided from a separate vaporizer via a first fuel supply line through a first vaporization chamber to a mixing zone upstream of the first reaction chamber,
- the fuel is mixed with air in the mixing zone and this fuel-air mixture is introduced into the first reaction chamber;
- a mixture of fuel and air is catalytically combusted,
- the electrical heating device is switched off.

The advantages associated with this can be seen, inter alia, in that the steps of the method according to the invention enable the fuel cell system to be heated efficiently and within a short time, and the burner itself to be heated efficiently and quickly. Heated to reduce cold start time. As soon as the fuel/air mixture has burned, the electric heating device is switched off. This is because the combustion produces heat which heats the first vaporization chamber. Fuel is then vaporized through the first vaporization chamber until the rated operating point is reached. As soon as the electrical heating device is switched off, a self-holding operating point is reached. That is, all method steps of the invention are performed to heat the fuel cell system so that it reaches its rated operating point. In this case, not only the reaction chamber of the burner is heated, but also in particular the evaporator arranged between the two reaction chambers.

In particular, it is preferred that the fuel is not only completely vaporized in a separate evaporator, but is also heated and at least partially pre-reformed. In this way, the electric heating device only has to be activated for the moment to heat or preheat the fuel until the operating temperature defined by the burner is reached. As soon as a defined operating temperature has been reached, the electrical heating device can be deactivated. Each remaining step in the method is then repeated. Other advantages and functions associated with the functional form of the burner as a starter burner are the same as those described in detail above with respect to the burner according to the invention and the fuel cell system according to the invention.

It is then even more preferred if the at least partially combusted fuel-air mixture is guided from the first vaporization chamber to the second vaporization chamber, which in turn is guided to the second reaction chamber. The mixture of fuel and air is completely catalytically combusted in the second reaction chamber and at the same time has a temperature in the range between 800° C. and 900° C. at the outlet of the burner, which is also the outlet of the second reaction chamber, and the process gas It has become.

In order to improve and/or promote the catalytic reaction in the second reaction chamber, the fuel is guided through the second fuel supply line to the cold side of the second vaporization chamber via a second regulator and vaporized. and is guided downstream thereof into a second reaction chamber. This fuel is vaporized in the second vaporization chamber, for which purpose the heat of the fuel-air mixture emerging from the first vaporization chamber is utilized. The vaporized fuel is subsequently guided to a second reaction chamber where it is mixed with the fuel-air mixture that was at least partially reformed in the first reaction chamber and completely catalytically combusted. The fuel-air mixture has a temperature of, for example, 650° C. or less downstream of the second evaporation chamber. This heat is released in particular to both vaporization chambers in order to evaporate the fuel.

The fuel-air mixture completely reformed in the second reaction chamber is then preferably used downstream of the burner for heating at least the reformer and the heat exchanger. The process gas leaving the burner has a temperature of between 800° C. and 900° C., in particular approximately 950° C., and can additionally or alternatively be used for heating the evaporator. When all parts of the fuel cell system are at operating temperature, the process gas, which is now cooled, is released into the environment.

The first adjusting device and/or the second adjusting device can advantageously be configured as an injector within the framework of the invention. Alternatively, the first adjusting device and/or the second adjusting device can be configured as at least one particularly controllable valve. However, it may also be provided that the first adjusting device and/or the second adjusting device comprise an injector and at least one valve.

As soon as the self-holding operating point of the fuel cell system has been reached, the control device is preferably switched off, thereby stopping the fuel supply via the fuel supply line. The burner is thus used as an afterburner, to which the fuel cell stack exhaust gas, which comprises in particular the anode exhaust gas and the cathode exhaust gas, is fed. A fuel cell stack is fed downstream of the fuel cell stack into a first reaction chamber where it is at least partially catalytically combusted and guided via both vaporization chambers into a second reaction chamber for complete combustion. be done. When the vaporization chamber is no longer supplied with fuel, the vaporization chamber also ceases to operate. While it may be advantageous if the burner is not supplied with air when the burner is functioning as an afterburner, it may also be preferable if the burner is at least temporarily supplied with air via the air supply line.

Further advantages, features and effects will become apparent from the examples described below. The drawings referred to at that time show the following.

1 is a schematic diagram showing a burner according to the invention; FIG. 1 is a cross-sectional view of a burner according to the invention; FIG. 1 is a block diagram to illustrate a fuel cell system according to an embodiment of the invention; FIG.

1 and 2 show a burner 1 or part thereof according to the invention for a fuel cell system 100. FIG. This burner contains reaction chambers 2, 3 arranged indirectly behind one another in the direction of flow. Each reaction chamber 2, 3 has a chamber inlet and a chamber outlet respectively. Furthermore, the burner 1 has a first fuel supply line 7 and an air supply line 8, the first fuel supply line 7 being designed for conducting fuel and the air supply line 8 for conducting air. configured for A mixture of ethanol and water is preferably used as fuel within the framework of the present invention. Between the two reaction chambers 2, 3 an evaporator 4 with two evaporator chambers 4a, 4b is provided. Arranged upstream of the evaporator 4 is a further evaporator 6 which includes an electrical heating device (not shown). The further evaporator 6 is arranged such that in its first part in the direction of flow the fuel is vaporized and in the second part of the evaporator in the direction of flow the fuel is at least partially reformed. The further evaporator 6 is thus simultaneously configured as a reformer and comprises an evaporator unit 6a and a reformer unit 6b, which is arranged downstream of the evaporator unit 6a and of which the Approximately double the volume is required. Furthermore, the further evaporator 6 contains an electrical heating device. For the introduction and transfer of fuel, a fuel supply line 7 is provided through which the fuel can be guided to the further evaporator 6 via the first injector 11 . The fuel supply line 7 leads further to the first evaporation chamber 4a, then to the mixing region 5 and to the first reaction chamber 2. FIG. The vaporized and at least partially reformed fuel downstream of the further vaporizer 6 and upstream of the first vaporization chamber 4a has a temperature of approximately 600.degree. This fuel is guided through the first evaporation chamber 4a, which has no other function during the starting phase. In the mixing area 5 , the vaporized and partially reformed fuel is mixed with air, which is led to the mixing area 5 via an air supply line 8 . The fuel-air mixture thereby generated is guided through the first reaction chamber 2, the first vaporization chamber 4a, the second vaporization chamber 4b and the second reaction chamber 3 to dissipate these components. Bring to operating temperature. A mixture of hot fuel and air heats both reaction chambers 4a, 4b, bringing the catalyst material to operating temperature and igniting it. As soon as this is done, the heating device is switched off. This usually lasts about 2 to 10 minutes. Further fuel is then supplied via the first injector 11 until the rated operating point is reached. Liquid fuel is guided to the first vaporization chamber 4a, where it is vaporized (via the heat of the fuel-air mixture guided via its hot side). The gasified fuel is then mixed with air in a mixing zone and guided to the first reaction chamber 2, where the fuel-air mixture is at least partially catalytically combusted. Arranged downstream of the first reaction chamber is a first vaporization chamber 4a in which the at least partially combusted fuel-air mixture flows through the cold side of the first vaporization chamber 4a. Used for fuel evaporation or heat exchange. As long as the rated operating point has not yet been reached, via the second injector 12 fuel is led through the second fuel supply line 9 to the second evaporation chamber 4b. That is, the fuel flows through the cold side of the second evaporation chamber 4b. Via the hot side of the second vaporization chamber, the at least partially already combusted fuel-air mixture is guided, the heat of this fuel-air mixture (approximately 650° C.) being transferred to the second fuel supply line. It is used to evaporate the fuel in 9. Both the fuel-air mixture and the already vaporized fuel are led to the second reaction chamber 3 where complete catalytic combustion takes place. The gas exiting the second reaction chamber 3 and thus from the burner 1 now has a temperature in the range 800° C. to 900° C. and heats the other components of the fuel cell system 100 . available for As soon as all components of the fuel cell system 100 reach operating temperature, the rated operating point is reached and both injectors 11, 12 are switched off.

In rated operation burner 1 is used as an afterburner and is supplied with stack exhaust gas via system exhaust line 10 so that it is completely catalytically combusted in burner 1 .

FIG. 3 shows a block diagram of a fuel cell system 100 with burner 1, not all details of burner 1 being shown. The fuel cell system 1 further comprises two fuel cell stacks 200 each having an anode section 300 and a cathode section 400 . In addition, a reformer 500 and a heat exchanger are provided. In addition, the fuel cell system 100 includes an evaporator 800 for evaporating the fuel guided toward the reformer 500 and a superheater 700 for superheating the fuel evaporated by the evaporator 800. there is Through the hot side of the reformer 500, the hot side of the superheater 700, and the hot side of the evaporator 800 is passed the stack exhaust gas, which provides the necessary heat for the process described above. The fuel cell system 100 operates on a mixture of liquid fuel and water, commonly referred to as fuel within the framework of the present invention. It passes from the fuel source 13 through the anode supply line to the evaporator 800 (where the fuel and water mixture becomes a gas), the superheater 700, and the reformer 500 (where the gaseous fuel and water mixture is reformed). ) into the anode section 300 . Air is supplied to cathode section 400 through heat exchanger 600 by blower 14 via cathode supply line 10 . These steps are performed as soon as the fuel cell system 100 is activated, ie after the heating operation.

For heating the fuel cell system 100 the burner 1 according to the invention is used as a start burner as explained above.

During operation of the fuel cell system 100, the burner 1 is used as an afterburner. The anode exhaust gas is mixed with the cathode exhaust gas downstream of the fuel cell stack 200 . This stack exhaust gas is fed to the burner 1 and is combusted there, preferably in two stages.

The burner 1 according to the invention can be used in a fuel cell system 100 both as a start burner and as an afterburner. The burner is used as a start burner when heating the fuel cell system 100 and as an afterburner when the fuel cell system 100 is in operation. The burner 1 is operated in the first step, during cold start (electrical heating is activated) and during the heating phase (electrical heating is switched off but injectors 11 and 12 are open). ) as a start burner and during rated operation (fuel is no longer supplied through the valves 11, 12) as an afterburner.

Claims (15)

1. A burner (1) for a fuel cell system (100), in particular for an SOFC system, said burner (1) being configured and arranged as a start burner and/or an afterburner, 2 arranged one behind the other. two reaction chambers (2, 3), the second reaction chamber (3) indirectly following the first reaction chamber (2) in flow direction, said reaction chambers (2, 3) each containing catalyst material , characterized in that an evaporator (4) is provided, said evaporator (4) being arranged between each of said reaction chambers (2, 3) ). 2. Burner (1) according to claim 1, characterized in that the evaporation device (4) comprises two evaporation chambers (4a, 4b). A mixing zone (5) is provided upstream of said first reaction chamber (2), said mixing zone (5) being arranged in particular near the chamber inlet of said first reaction chamber (2). Burner (1) according to claim 1 or 2, characterized in that. 4. According to any one of claims 1 to 3, characterized in that a further evaporator (6) is provided, said further evaporator (6) being arranged upstream of said evaporator (4). Burner (1) as described. Burner (1) according to claim 4, characterized in that said further evaporator comprises an electrical heating device. A first fuel supply line (7) is provided through which fuel is fed through said further evaporator (6) and said evaporator (4), in particular through the first evaporator. 6. The method according to any one of claims 1 to 5, characterized in that it can be guided through a chamber (4a) to the mixing area (5) and subsequently to the first reaction chamber (2). burner (1). An air supply line (8) is provided through which air can be guided to the mixing zone (5) and subsequently to the first reaction chamber (2). Burner (1) according to any one of claims 3 to 6, characterized in that. A second fuel supply line (9) is provided via which fuel can be guided through the second evaporation chamber (4b) to the second reaction chamber (3). A burner (1) according to any one of the preceding claims, characterized in that Claim 1, characterized in that a system exhaust gas line (10) is provided via which the system exhaust gas can be guided through the mixing region (5) to the burner (1). 9. A burner (1) according to any one of Claims 8 to 8. 10. A fuel cell system (100), in particular a SOFC system, with a burner according to any one of claims 1 to 9, wherein said fuel cell system comprises at least one anode section (300) and a cathode section (400). A fuel cell system (100) further comprising a fuel cell stack (200), a reformer (500) and a heat exchanger (600). A method of operating a fuel cell system (100) with a burner (1) according to claim 1, in particular a fuel cell system (100) according to claim 10, said method comprising the steps of
The electric heating device is activated, fuel is introduced via the first adjusting device into the first fuel supply line (7), and fuel is supplied via said first fuel supply line (7) to another guided to an evaporator (6) to at least evaporate the fuel;
air is introduced into the mixing zone (5) upstream of the first reaction chamber (2) via an air supply line (8);
Said mixing zone (5) upstream of said first reaction chamber (2) through said first vaporization chamber (4a) from said further vaporizer (6) via said first fuel supply line (7) The fuel is guided to
fuel is mixed with air in said mixing zone (5) and said fuel-air mixture is introduced into said first reaction chamber (2);
the mixture of fuel and air is catalytically combusted;
A method, wherein the electrical heating device is switched off. said at least partially combusted fuel-air mixture is guided from said first evaporation chamber (4b) to a second evaporation chamber (4b) and then to a second reaction chamber (3); 12. A method according to claim 11, characterized in that: Through a second adjusting device fuel is guided via a second fuel supply line (9) to the cold side of said second vaporization chamber (4b) where it evaporates and reaches the temperature of said second vaporization chamber (4b). 13. Process according to claim 12, characterized in that downstream is guided into the second reaction chamber (3). The fuel-air mixture completely reformed in the second reaction chamber (3) is supplied downstream of the burner (1) for heating at least a reformer (500) and a heat exchanger (600). 14. A method according to claim 13, characterized in that it is used for As soon as the self-retaining operating point of the fuel cell system (100) is reached, the regulators (11, 12) are switched off, thereby stopping the fuel supply via the fuel supply lines (7, 9). 15. A method according to any one of claims 11 to 14, characterized in that

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