Patent Document

CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This patent application claims priority to German Application No. 102011083407.9, filed Sep. 26, 2011, the entire teachings and disclosure of which are incorporated herein by reference thereto. 
     FIELD OF THE INVENTION 
     The present invention relates to a residual gas burner for a fuel cell system and to a fuel cell system having such a residual gas burner. 
     BACKGROUND OF THE INVENTION 
     A residual gas burner is usually part of a fuel cell system. The fuel cell system additionally comprises at least one fuel cell, which comprises an anode and a cathode. For operating the fuel cell, an anode gas for the anode and a cathode gas for the cathode are necessary, which are fed to the cathode and to the anode respectively. Through the electrochemical reactions which take place in and/or on the anode and the cathode during the operation of the fuel cell, an anode waste gas and a cathode waste gas develop. The residual gas burner serves for the further usage of the cathode waste gas and of the anode waste gas, which are fed to the residual gas burner as educt gases. To this end, the residual gas burner comprises two educt gas feeds, which feed the respective educt gas to a combustion chamber of the residual gas burner. The respective educt gas feeds comprise outlet openings, through which the respective educt gas enters the combustion chamber where it is combusted. The heat created through the combustion of the educt gases can then be fed for example via a heat transfer device to the cathode gas upstream of the fuel cell in order to increase the efficiency of the fuel cell or of the fuel cell system. Disadvantageous here is that the residual gas burner, in particular due to a poor mixing-through of the educt gases in the combustion chamber, has a low efficiency. In addition, such residual gas burners are very heavy and through their design, are complex to manufacture. 
     SUMMARY OF THE INVENTION 
     The present invention therefore deals with the problem of stating an improved or at least alternative embodiment for a residual gas burner of the type mentioned at the outset, which is characterized in particular through an improved efficiency and/or through an easy and cost-effective design. 
     According to the invention, this problem is solved through the subjects of the independent claims. Advantageous embodiments are subject of the dependent claims. 
     The present invention is based on the general idea of equipping a residual gas burner for a fuel cell system with two educt gas feeds, each of which comprise at least one outlet opening for letting out a respective educt gas into a combustion chamber of the residual gas burner, and arranging the outlet openings of the one educt gas closer to the combustion chamber than the outlet openings of the other educt gas. Because of this, an improved mixing-through of the respective educt gases prior to the combustion takes place, which leads to an improved and more stable combustion or flame within the combustion chamber and consequently improves the efficiency of the residual gas burner. The modulation capability of the residual gas burner is also improved towards higher lambda values because of this. 
     In particular, first outlet openings of a first educt gas lie in a first plane, while second outlet openings of a second educt gas lie in a second plane, which is further distant from the combustion chamber than the first plane. 
     Corresponding to the inventive idea, the residual gas burner comprises a first educt gas feed and a second educt gas feed, which serve for the feeding of the first educt gas and of the second educt gas to the combustion chamber of the residual gas burner. In addition, the first educt gas feed comprises at least one first outlet opening for letting out the first educt gas into the combustion chamber and is arranged on a first top surface of a first outlet channel system of the first educt gas feed. Furthermore, the second educt gas feed comprises a second outlet channel system, which comprises a top surface, which for letting out the second educt gas into the combustion chamber, comprises at least one second outlet opening. The second top surface of the second outlet channel system and the first top surface of the first outlet channel system additionally face the combustion chamber, wherein the first outlet channel system has a first bottom facing away from the first top surface, which first bottom faces the second top surface. This means, in particular, that the second outlet channel system and thus the at least one second outlet opening are spaced further from the combustion chamber than the first outlet channel system and thus the at least one first outlet opening. The respective outlet channel systems can each comprise a channel or a plurality of channels, wherein at least one of the channels comprises at least one associated outlet opening. The outlet channel systems as well as the top surfaces and the bottom surfaces can have any shapes, they consequently do not necessarily have a flat shape. 
     Feeding the respective educt gas to the associated channels can be additionally realised by means of feeding channels. The respective educt gas feeds can comprise one or a plurality of such feeding channels, which feeds/feed the respective educt gas for example from an inlet of the associated educt gas feed or the associated outlet channel system to the respective channels via a channel inlet or a plurality of channel inlets. 
     With a preferred embodiment, the second outlet channel system is arranged on the first bottom surface of the first outlet channel system. Practically, the first outlet channel system and the second outlet channel system are designed as separate components. Preferred is an embodiment, wherein the respective educt gas feeds and thus the respective outlet channel systems are designed as separate components. The arrangement of the second outlet channel system and thus of the second top surface on the first bottom surface of the first outlet channel system means in particular that the educt gas feeds are directly adjacent. The educt gas feeds in this case can be mechanically connected to each other, wherein the connection between the educt gas feeds can be realised in any way, provided they are suitable for the temperatures and pressures that are present there or in the combustion chamber. The separate design of the respective educt gas feeds has as a consequence in particular that the residual gas burner can be assembled from individual modules. This leads to a simplified and thus cost-effective production of the residual gas burner. In addition, the feeds or the channel systems can be structured in a simple manner, which facilitates a cost-effective production. 
     Practically, the first outlet channel system comprises at least one passage opening which allows the second educt gas flowing through the at least one second outlet opening to pass into the combustion chamber. The respective passage opening is spaced from the at least one first outlet opening and in the direction of the combustion chamber is in alignment with the at least one second outlet opening. 
     Preferred are embodiments, wherein the respective outlet channel systems each have a plurality of outlet openings. Accordingly, the first outlet system can also have a plurality of passage openings, which are spaced from the first outlet openings and each of which is in alignment with at least one of the second outlet openings. With a further embodiment, at least two of the first outlet openings have a different size. Also conceivable are embodiments, wherein at least two of the first outlet openings additionally or alternatively have a different shape. The same applies to the second outlet openings. This means that at least two of the second outlet openings have a different size and/or shape. 
     Here, according to a further preferred embodiment, the residual gas burner can be designed so that the first outlet openings are designed larger than the second outlet openings. This is practical, in particular, with embodiments, wherein the first educt gas feed is designed for larger flow rates than the second educt gas feed. This means that the residual gas burner is designed in such a manner that a volume of the first educt gas that is larger than that of the second educt gas can enter the combustion chamber. The first educt gas feed to this end can be designed larger or provide a larger flow cross section than the second educt gas feed for the associated educt gas. Accordingly, the first outlet openings can then be designed larger than the second outlet openings. 
     According to a preferred embodiment, the first educt gas feed is designed U-shaped and comprises two legs. The first outlet channel system in this case is preferably formed with pipes which run parallel between the legs. At least one of the pipes, preferentially however all, each form a first channel of the first outlet channel system, wherein the respective pipes are spaced from one another along a direction that runs transversely to the parallel arrangement in order to form between said passage openings of the first outlet channel system. Accordingly, the legs of the U-shaped educt gas feed can be designed as first feed channels and feed the first educt gas to the pipes. The first educt gas feed can thus comprise two first feed channels, which feed the first educt gas to the pipes via the ends of the pipes facing the legs. The respective first outlet opening is additionally arranged on the first top surface and thus on the top surface of one of the pipes. 
     Additionally, the respective first feed channel can comprise at least one bypass opening, which is arranged laterally or in a marginal region of the combustion chamber or connected to a bypass path leading passed the combustion chamber. The bypass openings in particular serve the purpose of reducing the flow rate of the first educt gas into the combustion chamber. Within a combustion chamber of the residual gas burner, a marginal region can be provided laterally of the combustion chamber, which is not assigned any second outlet openings, so that there only the bypass openings are provided and only the first educt gas enters into the marginal region. The educt gas flow entering the combustion chamber via the bypass openings is then guided laterally along walls of the combustion chamber enclosing the combustion chamber, which means a thermal relief of the combustion chamber walls. Optionally, at least one bulkhead can be arranged in the combustion chamber, which runs parallel to a combustion chamber wall and in at least one region adjoining the first surface separates the marginal region from the combustion chamber. Distally to the first surface, the respective bulkhead can be overflowable, so that the respective marginal region there is fluidically connected to the combustion chamber. Insofar as the respective marginal region is separated from the combustion chamber through at least one such bulkhead, the marginal region includes the bypass path at least partially passing by the combustion chamber. The bypass openings are preferentially arranged also on the first top surface. 
     If the opening arranged on the first feed channel serves as bypass opening, the first educt gas flowing out through it can also be utilised for cooling the combustion chamber or the residual gas burner. The bypass opening is arranged for example between the corresponding bulkhead of the combustion chamber and an outer wall or combustion chamber wall of the residual gas burner. These walls form a hollow space through which the first educt gas flowing out of the respective bypass opening can flow, and through which hollow space the bypass path leads. 
     The second top surface of the second outlet channel system can be designed as plate. The plate delimits a second channel of the second outlet channel system, which supplies all second outlet openings with the second educt gas. In other words, the second outlet channel system can merely comprise one single second channel, which supplies all second outlet openings with second educt gas, wherein the second outlet openings are arranged in the plate and accordingly on the second top surface. Here, the second channel and a second feed channel coincide or correspond to each other at least partially. 
     With an advantageous further development, the second outlet channel system or the second educt gas feed is produced in shell design. Accordingly, the second top surface can be formed as a second top surface shell, which with a second bottom surface designed as a second bottom shell forms the second outlet channel system or the second educt gas feed. 
     Also preferred is an embodiment, wherein the first outlet channel system or the first educt gas feed is produced in shell design. Accordingly, the first educt gas feed comprises a first top surface shell and a first bottom shell designed complementarily thereto, which form the first outlet channel system or the first educt gas feed. 
     Preferred is an embodiment, wherein both the first outlet channel system or the first educt gas feed as well as the second outlet channel system or the second educt gas feed are produced in shell design. The respective shells, i.e. the respective top surface shells and/or the respective bottom shells are produced for example through a deep-drawing method. The respective shells can be formed from sheet metal, in particular of iron metals and/or light metals through the deep-drawing and subsequently connected to each other. As examples for connecting possibilities of the respective shells, welding, soldering, screwing or gluing are pointed out here, wherein any types of the connection of the respective associated shells are conceivable provided these connection types are suitable for the thermodynamic conditions prevailing in the combustion chamber. Through the shell design of the shells formed in particular from sheet metal, a cost-effective production of the educt gas feeds and thus of the residual gas burner is possible. In addition, the weight of the residual gas burner is reduced because of this, which is advantageous in particular with mobile applications of the associated fuel cell system. 
     According to a further embodiment, the first outlet openings are arranged along preferentially straight first lines. A plurality of first outlet openings can then be arranged on different first lines in each case, wherein the respective first lines are preferentially arranged next to one another, in particular lie in a first plane and run parallel. Accordingly, the second outlet openings with a further embodiment are arranged on in particular straight second lines, wherein the second lines are preferentially arranged next to one another, run parallel to one another and can in particular lie in a second plane. The respective outlet openings arranged on one of the lines can have different sizes and/or shapes. 
     The outlet openings arranged on one of the lines can in particular become smaller along a flow direction in the respective channel. In particular, this serves the purpose of homogenising a flow rate of the respective educt gas into the combustion chamber. This means, the respective outlet openings are dimensioned or formed in such a manner that a flow velocity through all first outlet openings and/or all second outlet openings in each case is substantially the same. Reducing the outlet openings along the corresponding flow direction is based on the knowledge that the pressure in the respective educt gas in the respective channel increases along the flow direction of the educt gas due to the damming-up of the educt gas in the respective channel system. This is countered, insofar, that the size and thus a flow cross section of the outlet openings along the flow direction becomes smaller, as a result of which the mass flow or flow rates through all outlet openings of the associated educt gas feed can be adapted to one another. If a channel is supplied with educt gas via two feed channels on two channel inlets located opposite, the outlet openings of this channel can consequently be formed in such a manner that its size decreases towards the centre of the arrangement on the line. 
     Alternatively or additionally, the homogenisation of the flow rate of the respective educt gas can be realised through adapting the size of the associated channel inlets. The respective channel inlets can for example comprise a constriction, wherein the throttling effect of the constrictions along the flow direction of the associated educt gas in the feed channel supplying the channels or in the feed channels supplying the channels, increases. In other words, the flow cross section made available through the channel inlets becomes smaller along the flow direction in the associated feed channels, so that the pressure in the educt gas which increases through the damming-up can be offset along the flow direction. 
     Here, an embodiment is preferred, wherein the respective constrictions are integrally formed in the associated outlet channel system. The constrictions are thus realised through different shapes or sizes of the channel inlets. 
     A further possibility for configuring a homogeneous flow rate is the reduction in size of the channels or of the flow cross sections of the channels along the flow direction of the associated feed channel or the associated feed channels. 
     Additionally or alternatively, the feed channel or the feed channels can taper along the flow direction of the educt gas flowing within them in order to reduce their flow cross section along the flow direction. This is practically the case when along the respective feed channel at least two associated channels or at least two associated outlet openings are arranged, which this second feed channel supplies with second educt gas. 
     Preferred is an embodiment, wherein the first lines and second lines are each arranged next to one another. The first lines and the second lines in this case are preferably arranged alternating along a direction transversely to the longitudinal directions of the straight lines, wherein this longitudinal direction preferably is the flow direction in the respective channels. If for example the channels of one of the outlet channel systems are designed as pipes, the corresponding lines can run in particular parallel to the pipes. This means that the associated outlet openings are arranged line-like on the top surface of the pipes. 
     The bypass openings of the first feed channels can also be arranged along bypass lines, which practically extend along the associated first feed channel. These run transversely, in particular perpendicularly to the first lines. 
     The passage openings can be formed through linear elongated holes or slits, which are arranged next to one another, run parallel to the first lines and alternate with these, while they can practically lie in the first plane and are aligned with the second lines preferably perpendicularly to the first plane. 
     According to an advantageous further development, the first outlet openings are arranged line-like on first lines along the first channels of the first outlet channel system formed as pipes and/or of the at least one first feed channel, while the second outlet openings are arranged line-like on second lines which are in alignment with the passage openings formed through the spaced pipes. 
     With a further preferred embodiment, one of the educt gas feeds is configured as anode waste gas ducting of the fuel cell system. Preferentially, the first educt gas feed designed for larger flow rates is configured as cathode waste gas ducting, while the second educt gas feed is configured as anode waste gas ducting. Here, use is made of the knowledge that during the operation of a fuel cell of a fuel cell system more cathode gas than anode gas is used and consequently more cathode waste gas than anode waste gas is incurred, wherein the cathode gas and the anode gas each are fed to at least one anode arranged on the anode side or at least one cathode arranged on a cathode side of at least one fuel cell of the fuel cell system. In addition, a cooling gas, e.g. air, can be admixed to the cathode waste gas upstream of the combustion chamber. 
     With an advantageous further development of the solution according to the invention, a fuel cell system comprises a residual gas burner of the type described above. The fuel cell system comprises the at least one fuel cell, which comprises the anode side and the cathode side. Practically, one of the educt gas feeds is fluidically connected to the cathode side, while the other educt gas feed is fluidically connected to the anode side. Thus, the anode waste gas generated on the anode side can reach the combustion chamber of the residual gas burner through one of the educt gas feeds, while the cathode waste gas generated on the cathode side is fed to the combustion chamber through the other educt gas feed. Here, an embodiment is preferred wherein the first educt gas feed, which is designed for larger flow rates than the second educt gas feed, is fluidically connected to the cathode side, while the second educt gas feed is fluidically connected to the anode side. Consequently, anode waste gas flows into the combustion chamber through the second outlet openings facing the bottom surface while cathode gas flows into the combustion chamber through the first outlet openings. 
     Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the associated Figure description by means of the drawings. 
     It is to be understood that the features mentioned above and still to be explained in the following cannot only be used in the respective combination stated but also in other combinations or by themselves without leaving the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein same reference characters refer to same or similar or functionally same components. 
       There it shows, in each case schematically, 
         FIG. 1  a highly simplified representation of a fuel cell system in the manner of a circuit diagram, 
         FIG. 2  a top surface view of a first educt gas feed and a second educt gas feed of a residual gas burner, 
         FIG. 3  a lateral view of the residual gas burner, 
         FIG. 4  an exploded representation of the residual gas burner. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to  FIG. 1 , a fuel cell system  1  comprises at least one fuel cell  2 , which on an anode side  3  comprises an anode  4  and on a cathode side  5  comprises a cathode  6 . For operating the fuel cell system  1 , the anode  4  is supplied with an anode gas and the cathode  6  is supplied with a cathode gas. To this end, an anode gas feed  7  is provided, which feeds the anode gas to the anode  4  on the anode side  3 . In addition, a cathode gas feed  8  is provided, which feeds the cathode gas to the cathode  6  on the cathode side  5 . The fuel cell  2  converts the chemical energy that is created during the chemical reaction of the cathode gas and of the anode gas into electrical energy and feeds the electrical energy for example in the form of an electrical voltage to an electric consumer  10  by means of electrical lines  9 . In the process, anode waste gas generated on the anode side  3  and cathode waste gas on the cathode side  5 . The cathode waste gas and the anode waste gas are fed to a residual gas burner  13  of the fuel cell system  1  as a first educt gas (cathode waste gas) and a second educt gas (anode waste gas) via a cathode waste gas ducting  36  or a first educt gas feed  11  and an anode waste gas ducting  37  or a second educt gas feed  12 . The residual gas burner  13  comprises a combustion chamber  14 , which the educt gases enter by means of the first educt gas feed  11  and the second educt gas feed  12 . In the combustion chamber  14  a combustion of the educt gases takes place, in the process of which a hot burner waste gas is generated. The burner waste gas is conducted away from the residual gas burner  13  through a burner waste gas ducting  15 . The burner waste gas ducting  15  is connected to the cathode gas feed  8  by means of a heat transfer device  16  in a heat-transferring manner, so that the heat generated by the residual gas burner  13  is transferred to the cathode gas. 
       FIGS. 2 to 4  shows the residual gas burner  13 . The first educt gas feed  11  is designed U-shaped and comprises a first outlet channel system  17 , which comprises first channel  18  designed as pipes  18 , which run parallel between legs  19  designed as first feed channels  40  of the first educt gas feed  11  formed U-shaped. The channels  18  running parallel are additionally spaced from one another along a direction  38  running perpendicular to the parallel arrangement and thus form slit-like passage openings  20  of the first outlet channel system  17 . The first educt gas feed  11  and thus the first outlet channel system  17  additionally comprise a first top surface  21  facing the combustion chamber  14  delimited by walls  39 . For letting out the first educt gas into the combustion chamber  14 , first outlet openings  22  are arranged line-like along straight-line first lines  23  on the first top surface  21  of the first outlet channel system  17 , wherein in each case one of the first lines  23  runs along the pipes  18 . In addition, round bypass openings  47  are arranged on further straight bypass lines  46  along the first top surface  21  of the legs  19 . The bypass openings  47  are arranged laterally in a marginal region  48  of the combustion chamber  14 , so that the first educt gas flowing out through them is conducted laterally along the combustion chamber  14 . In a combustion chamber of the residual gas burner  13 , at least one bulkhead  39  can be provided, which separates the marginal region  48  from the actual combustion chamber  14 . Between the bulkhead  39  and a wall of the combustion chamber which is not shown, a hollow space can then be formed which serves as bypass path. Via this bypass path, the first educt gas can be conducted past the combustion chamber  14 . The bypass openings  47  running on the respective bypass lines  46  can thus be optionally arranged between such a bulkhead  39  of the combustion chamber  14  and an outer wall of the residual gas burner  13  which is not shown here, so that the bypass path leads through the hollow space thus formed and the associated educt gas can cool the residual gas burner  13  in the process. The respective bulkhead  39  can be configured overflowable distally from the first top surface  21 , so that the first educt gas enters the combustion chamber  14  from the bypass path there. If however such a bulkhead is missing, the first educt gas flowing along the outer wall of the combustion chamber can already enter the combustion chamber  14  along the walls. However, the first educt gas flowing along the combustion chamber wall can form a protective layer which reduces a thermal loading of the combustion chamber wall. 
     The first outlet openings  22  have a round shape, wherein the size of the first outlet openings  22  on the respective pipes  18  decreases towards the centre of the respective pipe  18 . The centre in this case refers to the spacing between the legs  19  of the first educt gas feed  11  running along the respective pipe  18 . The decrease of the size of the first outlet openings  22  is thus present along a first flow direction in the first outlet channel system  17  indicated through arrows  41 . The legs  19  of the first educt gas feed  11  merge into a first inlet  24  of the first outlet channel system  17 . The first educt gas thus flows from the fuel cell  6  via the first inlet  24  into the respective leg  19  and subsequently through the bypass openings  47 . Additionally, the first educt gas flows via the first inlet  24  into the respective leg  19  and via first channel inlets  42  into the respective pipes  18  and through the first outlet openings  22  into the combustion chamber  14 . All first channel inlets  42 , except for the channel inlets  42  of the pipe  18  next adjacent to the first inlet  24  each additionally comprise a constriction  43 , wherein the constrictions  43  increase in size along the flow direction  41  in the legs  19 . In addition, the constrictions  43  are integrally formed in the respective associated pipe  18  or in the first outlet channel system  17 . Accordingly, the respective constriction  43  can be described as bottle neck of the associated pipe  18 . 
     The second educt gas feed  12  comprises a second outlet channel system  25 , which comprises a second top surface  26  facing the combustion chamber  14 . In order to let the second educt gas flow into the combustion chamber  14 , round second outlet openings  27  are linearly arranged on the second lines  28  running linearly along second channels  44  arranged in parallel and on the second top surface  26  of the second outlet channel system  25 . The second top surface  26  faces a first bottom surface  29  of the first outlet channel system  11  facing away from the combustion chamber  14 . With the view shown in  FIG. 3 , the second outlet openings  27  are thus arranged below the first outlet openings  22  so that the second outlet openings  27  are spaced further from the combustion chamber  14  than the first outlet openings  22 . In addition, the bypass openings  47  are arranged above the first outlet openings  22 . Furthermore, the second lines  28  are arranged parallel to the first lines  23  running along the pipes  18  and perpendicularly to the bypass lines  46  running along the legs  18  in such a manner that they and thus the second outlet openings  27  run aligned with the passage openings  20  designed slit-like perpendicularly to a plane in which the first lines  23  lie. Thus, the second educt gas flowing through the second outlet openings  27  can enter the combustion chamber  14  through the passage openings  20 . The bypass openings  47  arranged along the bypass lines  46  running parallel to the legs  19  furthermore form the intersection between these first lines  23  and the second lines  28  in the top surface view shown in  FIG. 2 , so that along the flow direction in the first feed channels  40 , the bypass openings  47  and the first channel inlets  47  alternate. 
     As is evident in  FIG. 3 , the second outlet channel system  25  is arranged on the first bottom surface  21  of the first outlet channel system  17  by means of the second top surface  26 . In addition, the second outlet channel system  25  comprises a single second feed channel  30 , which supplies all second channel  44  with second educt gas. The second feed channel  30  in this case is arranged in the middle of the second educt gas feed  12 . The second outlet openings  27  and the second channels  44  are formed in a second outer shell  31  facing the combustion chamber  14  of the second educt gas feed  12  produced in shell design. The second educt gas feed  12  comprises a second inlet  33  for letting in the second educt gas into the second outlet channel system  17 , so that the second educt gas reaches into the second feed channel  30  along a second flow direction of the second educt gas indicated by arrows  45  via the second inlet  33  and then via the second channels  44 , the second outlet openings  27  and following this enters the combustion chamber  14  through the passage openings  20 . The second feed channel  30  additionally tapers along the second flow direction in the second feed channel  30 . 
     The first educt gas feed  11 , too, as is evident in  FIG. 4 , is produced in shell design. To this end, the first educt gas feed  17  comprises a first upper shell  34  facing the combustion chamber  14  and a first lower shell  35  formed complementarily thereto and facing away from the combustion chamber  14 . In  FIG. 4 , the region of the first inlet  24  is shown in the assembled state. 
     The respective lower shells  32 ,  35  and upper shells  31 ,  34  are each preferentially produced from a metal sheet through a deep-drawing method. In addition, the first educt gas feed  11  and the second educt gas feed  12  are formed as separate components. This makes possible a light, cost-effective and simple production of the residual gas burner  13 . In addition, by arranging the first outlet openings  22  and the second outlet openings  27  and the suitable constrictions  43  and the taper, an improved mixing-through of the educt gases can take place, as a result of which the combustion of the educt gases in the combustion chamber  14  of the residual gas burner  13  is stabilised, which leads to an increase of the efficiency of the residual burner  13 . 
     As is evident in particular in  FIGS. 3 and 4 , the first educt gas feed  11  is designed for larger gas flow rates than the second educt gas feed  12 , so that the first educt gas feed  11  with approximately identical flow velocities, makes possible larger flow rates than the second educt gas feed  12 . The fact that the different-size first outlet openings  22  are larger than the identical-size second outlet openings  27  also contributes to this. 
     Preferably, the first educt gas feed  11  is fluidically connected to the cathode side  5 , while the second educt gas feed  12  is fluidically connected to the anode side. In particular, this means that the first educt gas feed  11  is configured as the cathode waste gas ducting  36  while the second educt gas feed  12  is configured as the anode waste gas ducting  37 .

Technology Category: 2