WO2019075502A1 - BURNER FOR A FUEL CELL SYSTEM WITH TWO REACTION CHAMBERS - Google Patents

Abstract

The invention relates to a burner (1) for a fuel cell system (100), in particular an SOFC system, wherein the burner (1) is designed and arranged as start burner and / or afterburner, comprising a first operating fluid guide section (2) and a second operating fluid guide section (FIG. 3), the burner (1) comprising two reaction chambers (6, 7) arranged one after the other and each having a chamber inlet (4a, 4b) and a chamber outlet (5a, 5b), wherein a chamber inlet (4b) of a second reaction chamber ( 7) to a chamber outlet (5a) of a first chamber reaction chamber (6) follows, the reaction chambers (6, 7) each having a catalytic material (18). Furthermore, the invention relates to a use of such a burner (1) and a fuel cell system with such a burner (1). Furthermore, the invention relates to a method for operating a fuel cell system with such a burner (1).

Description

 Burner for a fuel cell system with two reaction chambers

The invention relates to a burner for a fuel cell system, in particular an SOFC system, wherein the burner is designed and arranged as start burner and / or afterburner, comprising a first Betriebsfluidleitabschnitt and a second Betriebsfluidleitabschnitt.

Furthermore, the invention relates to a use of such a burner.

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

Moreover, the invention relates to a method for operating a

Fuel cell system.

Burners for fuel cell systems are known from the prior art.

In particular, in SOFC systems, which are operated with liquid fuel such as diesel or ethanol or an ethanol-water mixture, it may be necessary to evaporate and reform the liquid fuel in a first step. In particular, when using water-containing ethanol, it is difficult to impossible, due to the high water content (about 55%), the fuel in a flame burner, which for example at

Fuel cell systems, which are operated with diesel, is used to burn.

Further, it is necessary to heat the fuel cell system at a cold start to an operating temperature, for which usually a so-called starting burner is provided. In addition, an afterburner is also usually necessary to completely burn exhaust gas from an anode section. Consequently, in known fuel cell systems usually a start burner and an afterburner are provided.

Under the starting burner is usually a starting burner for heating an afterburner of the fuel cell system, which in turn is provided for heating a reformer of the fuel cell system to understand. In a cold start of the fuel cell system, when the afterburner is still cold and is therefore not suitable for heating a reformer of the fuel cell system, the afterburner can be preheated by the starting burner. Once the Afterburner is by operating the fuel cell system to operating temperature, the starting burner can be disabled.

For example, DE 102 37 744 A1 discloses a fuel cell system with a starting burner, which is installed in a burner housing. In that

Burner housing can bypass air bypass flow along the outside of the starting burner before it enters together with emerging from the starting burner hot gas in a mixing zone. In the mixing zone, the bypass air is mixed as homogeneously as possible with the hot gas to emerge as a temperature-controlled hot gas stream and the

To heat fuel cell system.

Furthermore, from DE 10 2006 048 984 A1 a use of a

Burner device in a fuel cell system known. The

Burner device can be operated as an afterburner, with a

Mixture zone via a fuel gas inlet anode exhaust gas of a fuel cell or a fuel cell stack can be fed. The burner apparatus may continue to operate as a starting burner during a start-up phase of the fuel cell system in that the combustion mixture supplied to the burner apparatus is also in

Absence of a supply of anode exhaust gas is burned. However, it is not clear from this document how, in particular, a fuel cell system operated with a liquid fuel can be efficiently brought to operating temperature.

The object of the invention is to increase an efficiency of a burner of the type mentioned, by which it is simultaneously possible to reduce the number of components of a fuel cell system.

Another object is to provide a use of such a burner.

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

Further, it is an object of an improved method for operating a

Specify fuel cell system.

This object is achieved in that a burner of the aforementioned type comprises two successively arranged and each having a chamber inlet and a chamber outlet having reaction chambers, wherein in the flow direction a chamber inlet of a second reaction chamber to a Chamber exit a first chamber reaction chamber follows wherein the reaction chambers each have a catalytic material.

An advantage achieved thereby is, in particular, that such a

trained burner is designed and arranged both as a starting burner and as an afterburner and is or can be. That is, a single component functions simultaneously as a starting burner and as an afterburner, depending on one

Operating state of a fuel cell system in which the burner is arranged. The burner is designed as a two-stage burner, the first

Reaction chamber forms a first stage and the second reaction chamber forms a second stage. The first operating fluid and / or second operating fluid may be in

inventive burner on the one hand evaporated and at least partially reformed and on the other hand also completely burned and heated to a necessary or predefined temperature. A process gas, which flows out of the burner, has the same by the two-stage execution thereof

enough high temperature to over one or more

Heat exchanger elements fuel and air or operating fluids for a

Fuel cell stack to an operating temperature to heat. Further, in the burner fuel cell exhaust gas, which consists of an anode section and a

Cathode section exiting the fuel cell stack, completely

nachverbrennbar, with a separate afterburner is thus unnecessary, since the burner can be used in a single fuel cell system as start burner and afterburner. The burner according to the invention thus makes it possible to dispense with an element in a fuel cell system, since this unites two elements.

According to a first aspect of the present invention there is provided a burner for a fuel cell system, in particular for a SOFC system (SOFC stands for solid oxide fuel cell or solid oxide fuel cell) Such a fuel cell system can be operated, for example, with liquid fuel ,

The burner is in particular designed to catalytically combust liquid fuel, for which purpose both reaction chambers each comprise a catalytic material. The concept of the burner allows through the pre-evaporation and partial pre-reforming of the fuel in particular a use of an ethanol-water mixture as fuel, which is known to be due to its high water content is difficult to evaporate and subsequently burn. This makes it possible, the highly hydrous fuel, which for

Steam reforming is required without the necessary recirculation on the anode side, to use for the starting process. If the burner according to the invention is arranged in a fuel cell system, however, this can readily be operated with a liquid fuel-water mixture as with an ethanol-water mixture.

The first operating fluid guide section is arranged in particular as a component of the first reaction chamber and designed to supply a first operating fluid to the burner or the first reaction chamber. If the burner operates as a start burner, the second operating fluid guide section is designed to supply air to the burner. If the burner assumes the function of an afterburner, no operating fluid flows in the first operating fluid guide section in one embodiment variant, whereas in the second operating fluid guide section, anode exhaust gas or

Fuel cell exhaust gas (anode exhaust gas and cathode exhaust gas) flows, which is supplied to the burner to completely burn it. Since cathode exhaust gas is exclusively air in particular, the anode exhaust gas is burned in the burner with the cathode exhaust gas. In the case of too high a temperature in the operation of the burner as an afterburner, it may be advantageous to additionally supply air to the burner.

In a further embodiment variant, it may also be advantageous if, during operation of the burner as the afterburner in the first operating fluid guide section, the first

Operating fluid is performed. The reactions below are then carried out analogously to the operation as starting burner, except that the second operating fluid is not air but anode exhaust gas or fuel cell exhaust gas. The first operating fluid is preferably a liquid fuel-water mixture, in particular an ethanol-water mixture.

The two reaction chambers of the burner in particular directly adjoin one another, so that the chamber outlet of a first reaction chamber connects to the chamber inlet of the second reaction chamber. The two

Reaction chambers are successively flowed through by a mixture of air and a fuel-water mixture or fuel cell exhaust gas; the second reaction chamber is thus arranged downstream of the first reaction chamber. They are therefore arranged one after the other in the flow direction. It is advantageous if the reaction chambers are each formed at least in sections rotationally symmetrical, wherein these each comprise at least two, in particular cylindrical layers. Particularly preferably, the reaction chambers are each formed at least partially hollow cylindrical. The cylindrical layers are in particular coaxially inserted into one another or arranged to each other. As a result, chambers can form between the cylindrical layers.

It is advantageous if a first reaction chamber is an electrical

Heating device includes. As a result, the burner is electrically preheatable during a starting phase of the burner. In particular, the electrical heating means is designed for heating the first operating fluid, particularly preferably the heating means is designed exclusively for heating, evaporating and / or reforming the first operating fluid in a warm-up phase of the burner functioning as starting burner. The first operating fluid, which is present as a fuel or as a fuel-water mixture, is thus not only preheatable, but also vaporizable and pre-reformable to some predetermined degree.

As a result, the burner is particularly effective operable when used as a starting burner. For example, in a heating operation, the electric heater may operate for a period of about 2 minutes to 10 minutes. When using the burner as an afterburner, the electric heating means is not used in the rule. The electrical support for evaporation and

Although reforming can in principle be carried out in an external component, integration of this function is desirable for reasons of space.

In this case, it is advantageous if a first, radially outermost cylindrical layer of the first reaction chamber is designed as an evaporating jacket, wherein the electrical heating device is arranged running between the evaporation envelope and a second cylindrical layer and in particular at least partially spirally around a second cylindrical layer. As a result, the heating means is arranged particularly space-saving in the starting burner. Radially between the evaporation envelope and the second cylindrical layer is advantageously a

Evaporating chamber formed. The evaporation envelope encloses the

Evaporation chamber radially outside. The reactions taking place in the evaporation chamber (vaporization and pre-reforming of the first operating fluid) can be understood as a precursor or lower stage of the first stage of the burner. The Heating means, in particular, spiral over the second cylindrical layer over an approximately entire axial length of the first reaction chamber; it forms a heating spiral. In the context of the invention, all cylindrical layers are to be understood as meaning hollow-cylindrical layers unless otherwise clearly described.

Alternatively, the evaporation chamber and / or the evaporation envelope may also be arranged between the first and the second reaction chamber. In this case, it may again be favorable if an electrical heating device is provided, which is preferably arranged running between the evaporation envelope and a cylindrical layer of the evaporation chamber and, in particular, at least partially spirally around a cylindrical layer. Radial between the evaporation shell and the cylindrical layer is an advantage

Evaporating chamber formed. The evaporation envelope encloses the

Evaporation chamber radially outside.

In both variants, the first operating fluid, in particular a fuel-water mixture such as an ethanol-water mixture or a fuel is introduced in a first step in the evaporation chamber, which is heated by the electric heater. In the evaporation chamber, the first operating fluid is at least vaporized, in particular, it is vaporized and pre-reformed. Once the burner has reached a predetermined temperature, the electric

Heating device switched off. , In the flow direction downstream, the vaporized and in particular vorreformierte first operating fluid in the first

Passed reaction chamber in which this together with the second

Operating fluid, in particular air, is catalytically burned. The first

Reaction chamber is arranged either completely or at least partially radially within the evaporation chamber, so that in the catalytic

Combustion-generated heat can be used for vaporizing and pre-reforming the first operating fluid. If the evaporation chamber is arranged between the first and the second reaction chamber, either the first and / or the second reaction chamber extends radially inwardly at least partially into the evaporation chamber, so that at least part of the heat which is generated during the catalytic combustion is emitted and for evaporation and optionally pre-reforming the first operating fluid may be used. In particular, it is provided in the context of the invention that heat is extracted from the burner at least or exclusively in the first reaction chamber in order to evaporate the first operating fluid and optionally

vorzureformieren.

It is expedient if the first Betriebsfluidleitabschnitt at least partially extends spirally around the second cylindrical layer. In particular, the helical first operating fluid guide section formed thereby runs in such a way between the heating spiral formed that the heating fluid flows around the first operating fluid. As a result, the first operating fluid guided in the first operating fluid guide section is particularly efficient and can be heated in a short period of time. The first

Operating fluid is at one point in the spiraling first

Betriebsfluidleitabschnitt introduced, which is arranged closer to the chamber outlet than at the chamber entrance of the first reaction chamber. The helical first Betriebsfluidleitabschnitt ends approximately in the region of the chamber entrance of the first reaction chamber, where in an operation of the burner as a star burner, the first operating fluid is mixed with air and passed within a radially innermost cylindrical layer in the first reaction chamber. A distance to be covered of the first operating fluid in the spirally formed first

Thus, the operating fluid conduit is long enough to ensure that the first operating fluid is not only heated but also nearly or completely vaporized, and at least partially reformed or pre-reformed before it is mixed with air. The electric heater and the first

Betriebsfluidleitabschnitt each extend at least partially within the

Evaporation chamber. In this case, the heater is formed spirally and the first operating fluid flows around them. In order to specify a flow direction for the operating fluid, guide vanes are arranged in the vaporization chamber, so that the first operating fluid flows in a spiral towards the chamber inlet of the first chamber. The second cylindrical chamber can advantageously be provided with ribs on the walls in order to increase the heat transfer to the first cylindrical chamber as soon as the electrical support is switched off.

It is also advantageous if the first operating fluid guide section comprises at least two subsections, wherein a first subsection for supplying a first part of the first operating fluid to the chamber inlet of a first

Reaction chamber and a second section for supplying a second part of the first operating fluid is formed to the chamber entrance of the first reaction chamber. As described above, the first section is arranged spirally around the second cylindrical layer and advantageously conducts about 70% of the first operating fluid to the chamber entrance of the first as described

Reaction chamber. The second section is formed substantially shorter than the first section, but also extends spirally around the second cylindrical layer. By the second subsection about 30% of the first

Operating fluid passed, this part of the first operating fluid is directed towards the chamber outlet of the first reaction chamber. This is done in particular in an operation of the burner as a starting burner, but it can also be provided that when operating as an afterburner, the first operating fluid of the first chamber as described at least by the first or second

Subsection is fed.

It is advantageous if the second Betriebsfluidleitabschnitt is formed for supplying a second operating fluid to the chamber inlet of the first reaction chamber, wherein at the chamber inlet of the first reaction chamber, a shield for

Diverting the second operating fluid is arranged. In the area of

Chamber inlet of the first reaction chamber is carried out mixing of the gaseous, in particular partially reformed first operating fluid with the second operating fluid. The second operating fluid is in an operation as starting burner air, in particular ambient air, which can be supplied either directly via an external source or preferably via a cathode circuit of a fuel cell system. As a result of this, the second operating fluid designed as a fuel-water mixture is burned during operation as a starting burner. In order to achieve a particularly efficient mixing of the second operating fluid with the fuel-water mixture, the shield is provided, which is formed in particular circular and full surface and extends radially to about the second cylindrical layer. The incoming second operating fluid impinges on the shield and is directed by the latter in the direction of the incoming fuel-water mixture. By this arrangement, a poor mixing of the fuel-water mixture with the second operating fluid is largely avoided. Conveniently, the radially innermost cylindrical layer is perforated

Hollow cylinder is formed. The hollow cylinder is formed in particular of a metal or a metal alloy and forms a radially innermost element of the first Reaction chamber. The second operating fluid or a mixture of first and second operating fluid is passed via guide elements in an interior of the perforated wooden cylinder. Due to the radially formed perforations in the hollow cylinder, the second operating fluid or a mixture of first and second operating fluid is directed radially outwards in the direction of the second cylindrical layer.

It is advantageous if the catalytic material of at least the first

Reaction chamber is formed as a catalytically coated fabric, which is in particular arranged annularly around a radially innermost cylindrical layer. Basically, the catalytic material formed as a coated fabric is arbitrarily shapeable. It may be favorable if the catalytically coated fabric is metallic and has several recesses. in the

According to the invention, this is preferably arranged annularly on a wall of the radially innermost cylindrical layer. The fabric has a radially greater thickness than the innermost radial layer, the second cylindrical layer and the evaporation envelope. A radially inward end advantageously forms a catalyst inlet, whereas a radially outward end of the catalytic layer forms a catalyst exit. The fabric is preferably formed with a plurality of radial perforations or channels, so that it can be flowed through radially from the inside to the outside, wherein the first and / or second operating fluid are catalytically combusted. This has the advantage, in comparison to known from the prior art burners for fuel cell systems that a pressure drop of the mixture is significantly reduced by the catalyst-forming tissue. The catalytic material may also be spirally wound around the radially innermost layer. In addition, the catalytic material may have perforations. In order to coat the fabric, it may be immersed, for example, in a catalytic solution or sprayed with a catalytic solution. It is favorable if the fabric is metallic.

In order to utilize the heat generated during the catalytic combustion, heat-conducting elements are advantageously arranged between the coated fabric and the second cylindrical layer. By way of the heat-conducting elements, which may be formed, for example, as ribs, heat from the catalytic combustion in the tissue is radially outward to the spiral-shaped

Betriebsfluidleitabschnitt transferable. This allows the electrical

Heating device can be switched off already after a short period of time, in particular already after starting a catalytic reaction. That for the further evaporation of the first operating fluid in the first Betriebsleitabschnitt is thus provided by the catalytic combustion available.

In the first reaction chamber, the first operating fluid is particularly completely combustible. With the resulting waste heat is subsequently the first operating fluid in the first operating fluid supply line, in particular in the

Evaporation chamber, vaporizable and partially reformable before it is introduced into the chamber entrance of the first reaction chamber. Consequently, as soon as waste heat is generated, operation of the electric heating device can be dispensed with. In addition, it is heated by a resulting combustion gas only up to a temperature of about 600 ° C; the remaining heat becomes

Evaporation of the first operating fluid used. As a result, on the one hand a permissible maximum temperature of common catalytic materials of about 1000 ° C is not exceeded and on the other hand, individual hot spots in the first

Reaction chamber avoided, whereby the most homogeneous possible mixing is achievable.

It is advantageous if the second reaction chamber comprises a perforated hollow cylinder and a catalytically coated tissue, wherein the tissue at least partially surrounds the perforated hollow cylinder in the circumferential direction. In contrast to the first reaction chamber, a radially inner end advantageously forms a catalyst outlet, whereas a radially outer end forms a catalyst inlet. The fabric is preferably formed with a plurality of radial perforations or channels, so that it can be flowed through from radially outside to inside. In particular, the second reaction chamber is designed to increase a temperature of the process gas to a maximum temperature in a function of the burner as a starting burner, which is limited by catalytic material and is currently used at about 950 ° C materials. Since a portion of the first operating fluid is supplied to an axial end of the first reaction chamber, this is catalytically burned in the second reaction chamber, whereby the temperature of the process gas leaving the burner increases significantly. This is also made possible by the fact that in the second reaction chamber no waste heat of combustion is used for other purposes. By the two-stage burner so a maximum temperature of the process gas can be achieved without damaging the catalytic material of the burner. A lifetime of Burner is thus increased because a decomposition of the catalytic material is reduced, in particular almost avoided. In the second reaction chamber is a

Distribution between the first operating fluid and gaseous mixture homogeneous, which is why a temperature distribution in the second reaction chamber is homogeneous. Consequently, a maximum temperature of the process gas to be achieved can be better approximated. The operation of the second reaction chamber is essentially the same during operation as a starting burner and during operation as an afterburner.

It is favorable if the burner according to the invention is at least partially

in particular, completely made or manufactured by an additive process or 3-D printing. This is particularly preferably this one-piece produced.

A use of a burner according to the invention is advantageously carried out as

Starting burner and afterburner in a fuel cell system, which is operated with liquid fuel.

According to another aspect of the present invention is a

Fuel cell system provided with a burner as shown in detail above. The fuel cell system further has a

A fuel cell stack having an anode portion and a cathode portion and an evaporator and a reformer, wherein the burner for heating the reformer, the evaporator and a heat exchanger, which is responsible for the heating of the cathode portion to be supplied air arranged and configured. Thus brings a fuel cell system according to the invention with the same advantages, as described in detail with reference to the

inventive burners have been described. The fuel cell system is preferably an SOFC system. The reformer is preferred for reforming a fuel mixture, such as ethanol and water, into another

Fuel mixture, in this case hydrogen and carbon dioxide, designed. The reformed hydrogen can be used in a fuel cell stack for power generation. The burner is to heat the reformer means

Fuel cell exhaust configured by the fuel cell stack. At a

Advantageous development of the present invention, it is possible that a further heat exchanger is provided, wherein process gas, which from the

Burner exits through a warm side of the heat exchanger and flows through a cold side of the heat exchanger to a cathode section of the heat exchanger Fuel cell stack flows, heats. Furthermore, it may be favorable if an additional heat exchanger is arranged downstream of the fuel cell stack and upstream of the reformer or of the further heat exchanger.

This is for an adjustment of inlet temperatures of the operating fluids

(Fuel-water mixture and air) is formed. The aim is,

Keep temperature differences between the two operating fluids as low as possible, so that in the fuel cell stack thermal stresses are largely avoided. The fuel cell system according to the invention is

used in particular in a motor vehicle.

The further aim is achieved if a method of the type mentioned at the beginning comprises the following steps:

- to put into operation of an electric heater and introducing a first operating fluid in a first Betriebsfluidleitabschnitt to at least to evaporate the first operating fluid;

 - Introduce a second operating fluid through a second

 Betriebsfluidleitabschnitt to a chamber inlet of a first

 Reaction chamber;

 - Passing the first operating fluid via the first Betriebsfluidleitabschnitt to the chamber inlet of the first reaction chamber;

 - Mixing the first operating fluid with the second operating fluid at the chamber inlet of the first reaction chamber, wherein the second operating fluid is deflected by a shield;

 - Catalytic combustion of the working fluid mixture;

 - Turn off the electric heater.

An advantage achieved with this is to be seen in particular in the fact that a fuel cell system can be heated efficiently and in a short time by the steps of the method according to the invention, wherein the burner itself is warmed up efficiently and quickly. When operating the burner as a starting burner, the second operating fluid is air, whereas the first operating fluid is a fuel or a

Fuel-water mixture is. Once the operating fluid mixture is burned, the electric heater is turned off, as heat is generated by the combustion, through which the first operating fluid is heated and evaporated prior to introduction into the burner. In particular, the first operating fluid not only completely evaporated in the first Betriebsfluidleitabschnitt, but also at least partially pre-reformed. Thus, the electric heating device may initially be activated for heating or preheating the first operating fluid until a defined operating temperature has been reached in the burner or in the catalytic part of the burner. Once the defined operating temperature is reached, the electric heater can be deactivated. The remaining procedural steps are then repeated. The other advantages and functions associated with the operation of the burner as start-up burner are the same as described in detail above with reference to the burner according to the invention and to the burner

Fuel cell system according to the invention have been described.

It is further advantageous if a second part of the first operating fluid is supplied to a chamber outlet of the first reaction chamber, wherein the second part of the first operating fluid and the gaseous operating fluid mixture are passed into the second reaction chamber and catalytically burned in the second reaction chamber. Thereby, a process gas exiting the burner is increased to a desired and fixed process temperature without damaging the catalytic parts of the burner.

It is advantageous if emerging process gas is used downstream of the burner at least for heating a reformer and an evaporator, wherein the reformer and the evaporator, the first operating fluid is supplied. In the evaporator is thus due to the heated process gas in the burner, the first

(Liquid) operating fluid evaporates, wherein the first operating fluid is supplied to the evaporator via an anode supply line. In the reformer, which is arranged downstream of the evaporator, the now gaseous first operating fluid is reformed by the hot process gas. The emerging from the burner process gas has a temperature of about 950 ° C and can additionally or alternatively also be used to heat at least one heat exchanger, through which the air (second operating fluid), which is supplied to the cathode portion via a Kathodenzuführleitung heated becomes. In principle, it is favorable if the first and second operating fluid approximately with the same

Temperature are introduced into the fuel cell stack, which is why they are passed with advantage downstream of the heat exchanger through an additional heat exchanger, which balances temperatures of the two operating fluids. It is favorable in terms of method if the fuel is fed to the anode section downstream of the reformer, downstream of which

Fuel cell stack Anddenabgas mixed with cathode exhaust gas and the burner is supplied via the second Betriebsfluidleitabschnitt. Through this

Process step, the burner is used as an afterburner. As a result, the burner is used both as a starting burner and as an afterburner. Thus, a method according to the invention also brings about the same advantages as have been described in detail above with reference to the starting burner according to the invention and the fuel cell system according to the invention.

It is advantageous if the anode exhaust gas is burned in two stages with the cathode exhaust gas in the burner, wherein a supply of the first operating fluid via the first Betriebsfluidleitabschnitt is preferably stopped. Since cathode exhaust gas (air) is already admixed with the anode exhaust gas, it is advantageously no longer necessary to supply air. Although it is in a function of the burner as

Afterburner may be beneficial when the burner no first operating fluid is supplied, it may be advantageous if the burner over the first

Betriebsfluidleitabschnitt at least temporarily fuel or a fuel-water mixture is supplied.

After start-up of the burner as start burner this hot exhaust gas via heat exchanger promotes an anode section and a cathode section of a fuel cell system. By conveying ambient air over a cold side of a heat exchanger in the cathode circuit to the cathode section, the fuel cell system is heated. Once in the fuel cell system one

Operating temperature is reached, an anode current can be activated. At the same time a fuel supply to the starting burner is deactivated and the component

(Burner) goes into the passive operation of the afterburner, which the

Fuel cell exhaust aftertreated by total oxidation. This is possible because exit streams from the stack are directed directly into the chamber entrance of the burner.

Further advantages, features and effects will become apparent from the embodiments illustrated below. In the drawings, to which reference is made, show:

1 shows a burner according to the invention, 2 shows a further burner according to the invention;

3 shows a section through a burner according to the invention;

4 is a block diagram showing a fuel cell system according to an embodiment of the present invention.

Fig. 1 and 2 show a burner 1 according to the invention for a

Fuel cell system 100. This comprises two reaction chambers 6, 7, which are arranged one behind the other in the flow direction. Each reaction chamber 6, 7 has in each case a chamber inlet 4a, 4b and a chamber outlet 5a, 5b. The burner 1 further has a first Betriebsfluidleitabschnitt 2 and a second Betriebsleitabschnitt 3, wherein the first Betriebsfluidleitabschnitt 2 is designed to guide a first operating fluid and the second Betriebsfluidleitabschnitt 3 for guiding a second operating fluid. In the context of the invention, the first operating fluid is preferably an ethanol-water mixture and second

Operating fluid used air. The first operating fluid guide section 2 comprises a first section 2a and a second section 2b.

As can be seen from Figures 1 and 2, both a first reaction chamber 6 and a second reaction chamber 7 of the burner 1 are constructed as a hollow cylinder; These each have a plurality of cylindrical layers 8, 9, 10, 14, 15, 18. A radially innermost layer 10, 14 is in each case formed as a metallic, perforated hollow cylinder. Radially outward, both reaction chambers 6, 7 are closed with a radially outermost cylindrical layer 8, 16. The radially outermost

Cylindrical layer 8 of the first reaction chamber 6 is formed as an evaporating shell, between which and a second cylindrical layer 9, an evaporation chamber is formed. In the evaporation chamber, the first operating fluid is vaporized and pre-reformed.

FIG. 3 shows a section through the burner 1 according to the invention. The first reaction chamber 6 is constructed radially from the outside to the inside as follows: The radially outermost cylindrical layer 8 formed as the evaporation envelope includes a spiral-shaped electric heater 11, which spirally extends around a second cylindrical layer 9 and as in FIGS. 1 and 2 seen in the chamber inlet 4a of the first chamber 6 enters the evaporation shell. Also and alternately with the electric heater 1 1, the first runs Operating fluid guide section 2 around the second cylindrical layer 9 around. As a result, during a cold start of a fuel cell system 100, a first operating fluid may be heated and vaporized. Radially within the second cylindrical layer 9, heat-conducting elements 13 are arranged, which are connected to a catalytic layer 18

connect. Radially within the catalytic layer 18, the radially innermost layer 8 formed as a perforated hollow cylinder is arranged. The second

Reaction chamber 7 comprises less sub-element than the first reaction chamber 6 and is constructed radially from outside to inside as follows: An outermost cylindrical layer 16 closes the second reaction chamber 7 to the outside. Within this, a catalytic layer 18 is again provided. This is generally the same design as the catalytic layer 18 of the first reaction chamber. 6

Particularly preferably, the catalytic layers 18 of the first and second reaction chambers 6, 7 are formed as catalytically coated fabric 15; According to FIG. 3, the catalytic layer 18 thus corresponds in each case to the tissue 15. Radially inside, the radially innermost layer 14 designed as a metallic perforated hollow cylinder adjoins it. The fabric 15 extends radially around the perforated

Hollow cylinder, wherein both the hollow cylinder and the fabric 15 are formed with radially extending perforations.

Both reaction chambers 6, 7 each have a chamber inlet 4a, 4b and a chamber outlet 5a, 5b. In the area of the chamber entrance 4a of the first reaction chamber 6, a shield 12 for deflecting the second operating fluid is arranged. In order to guide the second operating fluid or a mixture of first and second operating fluid into an inner region of the innermost layer 8, further guide elements 17 are provided. Heated process gas flows out of the burner 1 via the chamber outlet 5b of the second reaction chamber 7.

4 shows a block diagram of a fuel cell system 100 with the burner 1. The fuel cell system 1 further includes an evaporator 140, a

Reformer 150, two heat exchangers 160, 170 and a fuel cell stack 1 10 with an anode portion 120 and a cathode portion 130. Das

Fuel cell system 100 is operated with a liquid fuel-water mixture, which via an anode feed 20 via the evaporator 140 (where the fuel-water mixture is gaseous), the reformer 150 (where the gaseous fuel-water mixture is reformed) and the other

Heat exchanger 170 is fed to the anode section. Over a The cathode supply line is supplied to the cathode section 130 via a heat exchanger 160 and the further heat exchanger 170. These steps are performed when the fuel cell system 100 is in operation, that is, after a heating operation.

For heating the fuel cell system 100 of the invention

Burner 1 used as a starting burner: The electric heater 1 1 is put into operation and the first operating fluid is in the first

Operating fluid guide 2 introduced. There, this is heated with the heater 1 1, evaporated and partially reformed. Shortly thereafter, air through a second Betriebsfluidleitabschnitt 3 and the fuel-water mixture for

Chamber inlet 4a of the first reaction chamber 6 introduced or passed and mixed there. The mixture is passed radially outward in the direction of the catalytic layer 18 and catalytically burned there. Since heat is given off by the combustion, the electric heater 1 1 can now be turned off. At the chamber outlet 5a of the first reaction chamber 6, a second part of the fuel-water mixture is supplied and this passed with the already gaseous fuel-water-air mixture in the second reaction chamber 7. There again takes place a catalytic combustion. One from the second

Reaction chamber escaping process gas now has a temperature of about 950 ° C. As shown in FIG. 4, this process gas heats up the reformer 150, the heat exchanger 160 and the evaporator 140 in the flow direction. The

incoming air to the heat exchanger 160 in turn heats the

Fuel cell stack 1 10 on. Once all the elements have a predefined one

Having operating temperature, the function of the burner 1 is no longer needed as starting burner, that is, it is preferably no first operating fluid supplied via the first Betriebsfluidleitabschnitt 2.

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 110. This stack exhaust gas is fed via the second Betriebsfluidleitabschnitt 3 the burner 1 and burned there in particular two stages.

According to FIG. 4, a valve 180 is furthermore provided in the fuel cell system 100. This is designed and arranged to the burner 1 optionally with To cool the air. This may be necessary, for example, when a battery, which is supplied with electrical energy provided by the fuel cell system 100, is full and can no longer be supplied. Then the fuel cell stack 1 10 automatically turns off. However, the superfluous fuel in the fuel cell system 100 is further promoted and not

Fuel cell stack 1 10 used, but the fuel goes directly through the fuel cell stack 1 10 in the burner. 1 There is a risk that the permissible in the burner 1 maximum temperatures will be exceeded, which is why the burner 1 is cooled by opening the valve 180 with air from the cathode supply line 30.

The burner 1 according to the invention can be used in a fuel cell system 100 both as a starting burner and as an afterburner. When the fuel cell system 100 is being heated, it is used as start burner and during operation of the fuel cell system 100 as an afterburner.

Claims

claims 1 . Burner (1) for a fuel cell system (100), in particular a SOFC system, wherein the burner (1) is designed and arranged as start burner and / or afterburner, comprising a first Betnebsfluidleitabschnitt (2) and a second Betnebsfluidleitabschnitt (3) characterized in that the burner (1) comprises two reaction chambers (6, 7) arranged one after the other and each having a chamber inlet (4a, 4b) and a chamber outlet (5a, 5b), one chamber inlet (4b) of a second one in the flow direction Reaction chamber (7) on a chamber outlet (5a) of a first chamber Reaction chamber (6) follows, wherein the reaction chambers (6, 7) each one catalytic material (18). 2. Burner (1) according to claim 1, characterized in that the Reaction chambers (6, 7) are each formed at least partially rotationally symmetrical, each comprising at least two, in particular cylindrical layers (8, 9, 10, 14, 15, 18). 3. Burner (1) according to claim 1 or 2, characterized in that the first reaction chamber (6) has an electrical heating device (1 1). 4. Burner (1) according to claim 3, characterized in that a first, radially outermost cylindrical layer (8) of the first reaction chamber (6) as Evaporating sheath is formed, wherein the electric heater (1 1) between the evaporation envelope and a second cylindrical layer (9) extending and in particular at least partially spirally around a second cylindrical layer (9) is arranged extending. 5. burner (1) according to one of claims 1 to 4, characterized in that the first Betriebsfluidleitabschnitt (2) at least partially spirally around the second cylindrical layer (9). 6. burner (1) according to one of claims 1 to 5, characterized in that the first Betriebsfluidleitabschnitt (2) at least two sections (2a, 2b), wherein a first section (2a) for supplying a first part of a first operating fluid to Chamber entrance (4a) of the first reaction chamber (6) and a second section (2b) for supplying a second part of the first Operating fluid to the chamber outlet (5a) of the first reaction chamber (6) is formed. 7. burner (1) according to one of claims 1 to 6, characterized in that the second Betriebsfluidleitabschnitt (3) for supplying a second operating fluid to the chamber inlet (4a) of the first reaction chamber is formed, wherein at the chamber entrance (4a) of the first reaction chamber ( 6) a shield (12) for deflecting the second operating fluid is arranged. 8. Burner (1) according to one of claims 1 to 7, characterized in that the radially innermost cylindrical layer (10, 14) of the reaction chambers (6, 7) is in each case designed as a perforated hollow cylinder. 9. burner (1) according to one of claims 1 to 8, characterized in that the catalytic material (18) of the at least first reaction chamber (6) as a catalytically coated fabric (15) is formed, which in particular annular around the radially innermost cylindrical layer (10) is arranged. 10. burner (1) according to claim 9, characterized in that between the coated fabric (15) and the second cylindrical layer (9) Heat conducting elements (13) are arranged. 1 1. Burner (1) according to one of claims 1 to 10, characterized in that the second reaction chamber (7) comprises a perforated hollow cylinder (14) and a catalytically coated fabric (15), wherein the fabric (15) the perforated hollow cylinder (14). surrounds in the circumferential direction at least partially. 12. Use of a burner (1) according to any one of claims 1 to 1 1 as start burner and afterburner in a fuel cell system (100), which is operated with liquid fuel. 13. Fuel cell system (100), in particular SOFC system with a burner (1) according to one of claims 1 to 1 1, characterized in that the Fuel cell system (100) further comprises a fuel cell stack (1 10) having an anode portion (120) and a cathode portion (130) and an evaporator (140) and a reformer (150). 14. A method for operating a fuel cell system (100) with a burner (1) according to one of claims 1 to 1 1, in particular one The fuel cell system (100) of claim 13, wherein the method comprises the steps of: - Put into operation an electric heater (1 1) and introduction  a first operating fluid in a first Betriebsfluidleitabschnitt (2) to at least evaporate the first operating fluid;  - Introduce a second operating fluid through a second  Betriebsfluidleitabschnitt (3) to a chamber inlet (4a) of a first reaction chamber (6);  - Passing the first operating fluid via the first Betriebsfluidleitabschnitt (2) to the chamber inlet (4a) of the first reaction chamber (6);  - Mixing the first operating fluid with the second operating fluid at the chamber inlet (4a) of the first reaction chamber (6), wherein the second operating fluid via a shield (12) is deflected;  - Catalytic combustion of the working fluid mixture;  - Turning off the electric heater (1 1). 15. The method according to claim 15, characterized in that at a chamber outlet (5a) of the first reaction chamber (6) a second part of the first operating fluid is supplied, wherein the second part of the first operating fluid and the gaseous operating fluid mixture in the second reaction chamber ( 7) and burned in the second reaction chamber (7) catalytically. 16. The method according to claim 15, characterized in that the resulting process gas is used downstream of the burner (1) for heating a reformer and an evaporator, wherein the reformer and the evaporator, the first operating fluid is supplied. 17. The method according to claim 16, characterized in that the fuel downstream of the reformer (150) is supplied to the anode portion (120) downstream of the fuel cell stack (1 10) mixed Anddenabgas with cathode exhaust gas and the burner (1) via the second Betriebsfluidleitabschnitt ( 3) is supplied. 18. The method according to claim 17, characterized in that the Anode exhaust gas is burned in two stages in the burner (1) with the cathode exhaust gas, wherein supply of the first operation fluid via the first operation fluid guide portion (2) is preferably stopped