Abstract:
A burner tip having a burner outlet opening includes a burner tip part ( 21 ) which surrounds the burner outlet opening and has a burner tip wall ( 21 A) with an end wall ( 67 ) forming a closed end of the burner tip part ( 21 ). The burner tip part ( 21 ) has in its interior a hollow space extending to the end wall ( 47 ), wherein the burner tip wall ( 21 A) has an inner side facing towards the hollow space. A displacement body in the hollow space has an outer side facing towards the inner side of the burner tip wall ( 21 A), forming at least one flow channel between the inner side of the burner tip wall ( 21 A) and the outer side of the displacement body. In a first aspect, the displacement body ( 15 ) is connected to the inner side of the burner tip wall ( 21 A) by supporting structures ( 56 ), which extend from the outer side of the displacement body to the inner side of the burner tip wall ( 21 A). In a second aspect, swirl blades ( 32 ) project at least partially into the burner outlet opening ( 3 ), and the burner tip wall ( 21 A). The swirl blades are each a single piece with that wall.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a 35 U.S.C. §§371 national phase conversion of PCT/EP2013/072422, filed Oct. 25, 2013, which claims priority of European Patent Application No. 12197209.5, filed Dec. 14, 2012, the contents of which are incorporated by reference herein. The PCT International Application was published in the German language. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a burner tip, especially to a burner tip for high-temperature applications in synthesis gas production. In addition, the invention relates to a burner, especially to a burner for synthesis gas production. 
       TECHNICAL BACKGROUND 
       [0003]    A burner for a synthesis gas reactor is described schematically in DE 10 2008 006 572 A1. This comprises an outer burner element having a tip with a cavity and with a displacement body arranged in the cavity. Guided around the displacement body is a cooling water passage for cooling the burner tip. The burner also comprises an inner burner element which is arranged concentrically to an outer tube. A passage is formed between the inner burner element and the outer burner element for the feed of a pulverized fuel, for example pulverized coal. Also, in the region of its tip, the inner burner element has a cavity with a displacement body arranged therein. A cooling water passage is guided around the cavity and cools the tip of the inner burner element. 
         [0004]    A pilot burner is arranged centrally to the inner burner element, wherein a feed passage for an oxygen/steam mixture is formed between the inner burner element and the pilot burner. Like the outer and the inner burner elements the pilot burner is of a hollow walled design, having a displacement body in the region of the tip of the pilot burner and around the body is guided a cooling water passage to be able to cool the pilot burner tip. 
         [0005]    The tips of burners in synthesis gas reactors are subjected to high temperatures during operation of the reactors providing a considerable heat input into the burner tip. The inputted heat is dissipated by means of the cooling water flowing in the described cooling water passages. In order to reduce the heat input, the burner tip can also be provided with a thermal barrier coating, as is described in DE 10 2008 006 572 A1. 
         [0006]    The respective burner elements are usually constructed from a plurality of tubes and a tip which interconnects the tubes and in which a displacement body is also arranged. The tip in this case is usually assembled from an outer annular part and an inner annular part, wherein the outer annular part is connected to the outer tube and the inner annular part is connected to the inner tube. Moreover, the annular parts are welded together by their ends which face away from the outer tube or the inner tube. The displacement body is connected to a centrally arranged tube which divides the interspace between the outer tube and the inner tube into an annular feed passage for cooling water and an annular discharge passage for cooling water. Each burner element therefore has a complex construction. Furthermore, the burner tips are relatively large, and therefore heavy, which reduces their manageability, for example in the course of maintenance. 
         [0007]    For production engineering reasons, the wall thicknesses of the tubes or of the tip parts are typically at least 3 mm, which makes heat dissipation difficult and increases the susceptibility to temperature fluctuations. Furthermore, suspended particles and cooling water can lead over time to a constriction of the cooling water passages in the region of the burner tip or even to blocking of the cooling water passages, which entails an increased maintenance requirement so that such constrictions can be discovered in good time. 
         [0008]    Moreover, the materials from which the burner tips are produced are expensive and time consuming in processing since the parts of which the burner tips consist have to be welded together. The welding of the parts for forming the respective burner tip is not simple since the typically used nickel-based superalloys require special welding procedures. 
       SUMMARY OF THE INVENTION 
       [0009]    Compared with the described prior art, it is the object of the present invention to provide an advantageous burner tip, especially for burner elements of a synthesis gas burner. In addition, it is an object of the present invention to provide an advantageous burner, especially for synthesis gas production. 
         [0010]    According to a first aspect of the invention, provision is made for a burner tip with a burner discharge orifice and at least one burner tip part which encompasses the burner discharge orifice and has a burner-tip wall with an end wall which forms a closed end of the burner tip part. The burner tip part in its interior has a cavity which reaches up the end wall and the burner-tip wall has an inner side pointing towards the cavity. A displacement body, with an outer side facing the inner side of the burner-tip wall, is arranged in the cavity, wherein at least one flow passage is formed between the inner side of the burner-tip wall and the outer side of the displacement body. The displacement body is connected to the inner side of the burner-tip wall via support structures which extend from the outer side of the displacement body to the inner side of the burner-tip wall. 
         [0011]    By means of the support structures, the position of the displacement body inside the burner-tip wall can be fixed. Furthermore, the entire structure consisting of burner-tip wall and displacement body can be of an altogether more stable design. 
         [0012]    The support structures can be designed especially as rib-like or pillar-like structures, wherein adjacent rib-like or pillar-like structures converge to form arches on the outer side of the displacement body and/or on the inner side of the burner-tip wall, at least in the region of the burner tip end wall. These arches can especially be designed as pointed arches similar to the arches in gothic architecture. The design of the support structures as rib-like or pillar-like structures with converging arches enables the production of the burner tip by means of an additive manufacturing process, for example by means of selective laser melting. 
         [0013]    In a specific embodiment of the burner tip with support structures, the density of support structures, which connect the displacement body to the burner-tip wall, is increased at least in the region of the end wall in comparison to other regions of the burner-tip wall. Where the density of the support structures is increased, the burner-tip wall can then be of a thinner design in comparison to regions without increased density of support structures. They can especially have thicknesses of below 3 mm, for example thicknesses in the region of 0.5 to 2 mm. In this way, in regions which are subjected to especially high temperatures and/or to especially pronounced temperature fluctuations the heat which is absorbed by the burner-tip wall can be dissipated more rapidly to the cooling fluid. As a result, the thinner wall can be kept cooler than a thicker wall, which in turn has a favorable effect upon the available operating period up to a maintenance. 
         [0014]    Within the scope of the burner tip according to the invention, the displacement body can especially be formed in one piece with the support structures and the burner-tip wall. This allows a particularly stable structure and enables the production with a large number of structures at the outset. The production, as already mentioned, can in this case be carried out by means of an additive manufacturing process, for example by means of selective laser melting. 
         [0015]    The burner-tip wall can be lined with a thermal barrier coating, at least in the region of the end wall. In particular, if the burner-tip wall has thicker and thinner regions, an embodiment in which the thermal barrier coating is applied to the thinner regions, especially in the region of the end wall, is advantageous. Due to the fact that in this embodiment the burner-tip wall is thinner in the regions with a thermal barrier coating, it can achieve the effect of the entire wall thickness in these regions, despite the applied thermal barrier coating, not exceeding the thickness of the remaining regions without a thermal barrier coating. 
         [0016]    The displacement body in the burner tip according to the invention can especially be of hollow design. As a result of the hollow design of the displacement body, a saving can be made in weight and material in comparison to burner tips according to the prior art in which the displacement body is designed as a solid body. On account of the lower weight, the burner tip, which can have diameters of  50  cm and more, is easier to manage, for example in the course of a maintenance or repair process. 
         [0017]    In a development of the embodiment variant with a hollow displacement body, this has near end in relation to the end wall, a far end in relation to the end wall, an interior space, and, in the region of the far end, has at least one opening which is open towards the interior space. In this way, it becomes possible to make the hollow displacement body accessible to a cooling fluid, for example cooling water, flowing through the flow passage between the outer side of the displacement body and the inner side of the burner-tip wall. To this end, for example a flow guiding element can be arranged in the displacement-body opening in such a way that it divides the displacement-body opening into an inflow section and an outflow section and in such a way that a flow path around the flow guiding element is formed between the inflow section and the outflow section. Alternatively, there is the possibility that the displacement body has at least one additional opening which is open towards the interior space. This is then arranged between the near end of the displacement body and the displacement-body opening which is arranged in the region of far end. Between the displacement-body opening and the additional displacement-body opening, the displacement-body interior space forms a flow path for cooling fluid, such as cooling water. 
         [0018]    If a flow path for cooling fluid is formed inside the hollow displacement body, a collecting chamber, branching from the flow path, for foreign bodies in the fluid flowing through the flow path can be located in the displacement-body interior space. In this case, it is advantageous if the collecting chamber in the displacement-body interior space is located in a region of the flow path in which a change of flow direction takes place. It is especially advantageous if the change of flow direction entails a substantial flow reversal. In this case, the space in the hollow displacement body is sufficient in order to provide an adequately large collecting chamber. The collecting of foreign bodies, such as suspended particles, in the cooling fluid leads to the fluid passages leading around the outer side of the displacement body blocking more slowly and as a result a constriction of the flow cross section can be delayed for a longer period. This in turn has a favorable effect upon the maintenance intervals. 
         [0019]    In the burner tip according to the invention, swirl vanes, which at least partially project into the burner discharge orifice, can also be formed in one piece with the burner-tip wall. Previously, swirl vanes have been inserted from the burner side facing away from the burner tip into the burner discharge orifice which is encompassed by the burner-tip wall. With this insertion, damage to the swirl vanes and/or to the burner tip wall can occur. As a result of the one-piece design of the swirl vanes with the burner-tip wall, the insertion of swirl vanes is superfluous. Moreover, there is also the possibility that the flow passage which is formed between the inner side of the burner-tip wall and the outer side of the displacement body also extends at least partially through the swirl vanes. In this way, a common cooling of burner tip and swirl vanes is made possible. By means of specific manufacturing processes (additive manufacturing processes) the swirl blading assembly can also additionally be given the form of a nozzle which decreases the flow passage of the oxygen-steam mixture in specific regions. 
         [0020]    In the burner tip according to the invention, the burner-tip wall and the displacement body are of toroidal design. 
         [0021]    According to a second aspect of the invention, provision is made for a burner tip with a burner discharge orifice and at least one burner tip part which encompasses the burner discharge orifice and has a burner-tip wall with an end wall which forms a closed end of the burner tip part. According to the second aspect of the invention, swirl vanes, which at least partially project into the burner discharge orifice, are formed in one piece with the burner-tip wall. 
         [0022]    Previously, swirl vanes were inserted from the burner side facing away from the burner tip into the burner discharge orifice which is encompassed by the burner wall. With this insertion, damage to the swirl vanes and/or to the burner tip wall can occur. As a result of the one-piece design of the swirl vanes with the burner-tip wall, the insertion of swirl vanes is superfluous. 
         [0023]    In a development of the burner tip according to the second aspect of the invention, the flow passage which is formed between the inner side of the burner-tip wall and the outer side of the displacement body also extends at least partially through the swirl vanes. In this way, a common cooling of burner tip and swirl vanes is made possible. 
         [0024]    With the aid of specific manufacturing processes (additive manufacturing processes), it can achieve the effect of the swirl vanes forming a blading assembly which has the form of a nozzle which reduces the flow cross section for an oxygen-steam mixture flowing through the blading assembly in specific regions of said blading assembly. 
         [0025]    A burner according to the invention is provided with a burner tip according to the invention. The characteristics and advantages associated therewith are gathered from those of the burner tip according to the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    Further features, characteristics and advantages of the present invention arise from the following description of exemplary embodiments with reference to the attached figures. 
           [0027]      FIG. 1  shows a schematic diagram of a burner, as is used in synthesis gas reactors. 
           [0028]      FIG. 2  shows the tip of a first burner element. 
           [0029]      FIG. 3  shows the tip of a second burner element. 
           [0030]      FIG. 4  shows the tip of pilot burner used in the burner. 
           [0031]      FIG. 5  shows an alternative embodiment of the tip from  FIG. 3 . 
           [0032]      FIG. 6  shows a further alternative embodiment of the tip from  FIG. 3 . 
           [0033]      FIG. 7  shows yet another alternative embodiment from  FIG. 3 . 
           [0034]      FIG. 8  shows the embodiment from  FIG. 7  in a section along the line VIII-VIII. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0035]    The basic construction of a burner for synthesis gas reactors is described below with reference to  FIG. 1 . 
         [0036]    The burner is constructed in a rotationally symmetrical manner around a burner axis A and comprises a tubular feed line section and a burner tip  1  which is connected to the feed line section and encompasses a burner orifice  3 . 
         [0037]    Referring to  FIGS. 1 and 2 , the burner comprises a first, outer burner element  2  which in the tubular section of the burner is formed from three inter-inserted tubes  4 ,  6 ,  8 . Formed between the tubes are a cooling fluid feed passage  7  and a cooling fluid discharge passage  9 , via which cooling fluid can be fed to the burner tip  1  and discharged from this respectively. As cooling fluid, water is especially considered. In the region of the burner tip  1 , the outer burner element  2  deviates from the pure tubular shape and is inclined in the direction towards the center of the burner discharge orifice  3 . Furthermore, in the region of the tip it has a cavity in which a displacement body  5  is arranged at a distance from the wall of the burner element  2  in this region. Formed in this case between the inner side of the wall  11 A of the burner element  2  in the tip region and the outer side of the displacement body is a flow passage  10  by means of which the cooling fluid, for example water, is directed through the tip of the outer burner element  2  in order to cool this. The part of the outer burner element  2  which deviates from the tubular shape constitutes an outer burner tip part  11  which is formed as an independent part and the wall  11 A of which is welded to the tubular section of the outer burner element  2 . 
         [0038]    In this case, the wall  11 A of the burner tip part  11  has an approximately U-shaped bend so that it can be connected both to the outer tube  4  and to the inner tube  8  of the tubular section of the outer burner element  2 . The displacement body  5  is fitted onto the center tube  6 . To this end, it has a groove  5 A, the width of which is adapted to the wall thickness of the center tube  6  of the tubular section. 
         [0039]    Referring to  FIGS. 1 and 3 , the burner furthermore comprises an inner burner element  12  which apart from in the region of the burner tip  1  is also formed from three inter-inserted tubes  14 ,  16 ,  18 . In the region of the burner tip  1 , an inner burner tip part  21 , with a cavity located therein, is connected to the tubular section of the inner burner element  12 . A displacement body  15  is arranged in this cavity, wherein the outer side of the displacement body has a distance from the inner side of the burner-tip wall  21 A in the region of the inner burner tip part  21  so that a flow passage is formed between the two. The feed of cooling fluid into the flow passage is carried out via a feed passage  17  which is formed between the inter-inserted tubes  14 ,  16  of the tubular section of the inner burner element  12 , and the discharge of the cooling fluid from the region of the inner burner tip part  21  is carried out via a discharge passage  19  which is formed between the inter-inserted tubes  16 ,  18 . Also, the inner burner tip part is designed as an independent part, the wall  21 A of which is welded to the outer tube  14  and to the inner tube  18  of the tubular section. To this end, the wall  21 A in the widest sense is bent in a U-shaped manner so that it can be welded both to the outer tube  14  and to the inner tube  18  of the three inter-inserted tubes  14 ,  16 ,  18  of the tubular section. The displacement body  15  is fitted onto the center tube  16  of the tubular section. To this end, it has a groove  15 A, the width of which is adapted to the wall thickness of the center tube  16 . 
         [0040]    The inner burner element  12  has an outside diameter which is smaller than the inside diameter of the outer burner element  2  so that an annular passage is formed between the two, serving for the feed of a pulverized fuel, for example for the feed of pulverized coal. 
         [0041]    The inner burner element  12  encloses a largely cylindrical chamber in which is arranged a pilot burner  22 . Referring to  FIGS. 1 and 4 , this pilot burner comprises a tubular section  22 A which is formed from three tubes  24 ,  26 ,  28  and to which is connected a pilot burner tip part  31  in the region of the burner tip  1 . The pilot burner tip part  31  has a cavity in which is arranged a displacement body  25 , wherein the outer side of the displacement body has a distance from the inner side of the wall  31 A of the pilot burner tip part  31  so that a flow passage  30  is formed between the two. As in the case of the outer burner element  2  and in the case of the inner burner element  12 , the wall  31 A of the tip part  31  is welded to the tubular section. The wall  31 A of the pilot burner tip part  31  is bent in this case in the widest sense in a U-shaped manner so that on one side it can be welded to the outer tube  24  of the tubular section of the pilot burner  22  and to the inner tube  28  of the tubular section of the pilot burner  22 . The displacement body  25  is fitted onto the center tube  26  of the tubular section. To this end, it has a groove  25 A, the width of which is adapted to the wall thickness of the center tube  26 . 
         [0042]    Referring to  FIGS. 1 and 4 , the tubular section of the pilot burner  22  has an outside diameter which is smaller than the inside diameter of the inner burner element  12  so that an oxygen/steam passage  23  is formed between the two. This serves for the feed of water vapor which is required in the synthesis gas reactor for converting pulverized fuel into synthesis gas, and, if necessary, for the feed of oxygen or air. For promoting the synthesis gas reaction, the supplied water vapor, and, if necessary, the supplied oxygen or the supplied air, is swirled in order to promote the synthesis gas reaction. 
         [0043]    To this end, swirl vanes  32  are arranged in the region of the burner tip  1  between the inner burner element  12  and the pilot burner  22 . 
         [0044]    The pilot burner  22  encloses an essentially cylindrical cavity in which are arranged an ignition burner and a device for flame monitoring. These two elements are shown in only a greatly schematized form in  FIG. 1  and are grouped under the designation  33 . 
         [0045]      FIG. 2  shows the construction of the outer burner tip part  11 . Also to be seen are the inter-inserted tubes  4 ,  6 ,  8  of the tubular section of the outer burner element  2 . The outer burner tip part  11  terminates in an end wall  34  which constitutes the end of the outer burner tip part. A cavity, in which, as already described, the displacement body  5  is located, is formed in the outer burner tip part  11 . This displacement body, as is shown in  FIG. 2 , is of hollow design. It has a near end  36  in relation to the end wall  34  and a far end  38  in relation to the end wall with a groove  5 A for fitting onto the center tube  6  of the tubular section of the burner element. In the region of the far end  38 , especially directly in front of the groove  5 A in the far end, provision is made for a displacement-body opening  40  which is open towards the interior space  42  of the hollow displacement body  5  so that the interior space  42  is accessible through the displacement-body opening  40 . The burner-tip wall  11 A, which is bent in an approximately U-shaped manner, is connected both to the outer tube  4  and to the inner tube  8  of the tubular section of the outer burner element  2 , whereas the displacement body  5  is connected to the center tube  6  of the tubular section of the outer burner element  2  in such a way that the displacement-body opening  40  is open towards the feed passage  7  which is formed between the outer tube  4  and the center tube  6 . The displacement-body interior space  42  is consequently fluidically connected to the feed passage  7  for the cooling fluid. 
         [0046]    The hollow displacement body  5 , which consists in the main of a relatively thin wall  44 , is connected to the inner side of the burner-tip wall  11 A via support structures  46 . These support structures can be of rib-like or pillar-like design so that they obstruct the flow in the flow passage  10  as little as possible and possibly even guide the flow. 
         [0047]      FIG. 3  shows the construction of the inner burner tip part  21  and the inter-inserted tubes  14 ,  16 ,  18 , adjoining it, of the tubular section of the inner burner element  12 . The inner burner tip part  21  has a wall  21 A with an end wall  47  which forms the closed end of the inner burner tip part  21 . As has already been described with reference to  FIG. 1 , a displacement body  15  is located in the cavity of the inner burner tip part  21 . This displacement body in turn is itself of hollow design and has a wall  54  enclosing an interior space  52 . Furthermore, the displacement body  15  has a near end  48  in relation to the end wall  47  and a far end  49  in relation to the end wall  47  with a groove  15 A for fitting onto the center tube  16  of the tubular section of the burner element. Arranged in the region of the far end  49 , especially directly in front of the groove  15 A in the far end, is a displacement-body opening via which the displacement-body interior space  52  is accessible. The wall  21 A of the inner burner tip part  21  is bent in an approximately U-shaped manner, wherein the ends of the burner-tip wall  21 A are connected to the outer tube  14  of the tubular section of the inner burner element  12  and to its inner tube  18 . The displacement-body wall  54  is connected to the center tube  16  of the tubular section of the inner burner element  12  so that the displacement-body opening  50  is open towards the feed passage  17  formed between the outer tube  14  and the center tube  16  of the tubular section of the inner burner element  12 . In this way, the displacement-body interior space  52  is fluidically connected to the feed passage  17  for the cooling fluid. The displacement-body wall  54  is connected via support structures, which for example can be of rib-like or pillar-like design, to the inner side of the burner-tip wall  21 A so that a defined distance is provided between the outer side of the displacement body and the inner side of the burner-tip wall  21 A in order to form the flow passage  20 . As in the case of the outer burner tip part, the support structures can also be designed in such a way that they guide the flow through the flow passage, but in any case they are designed so that they obstruct the flow as little as possible. 
         [0048]    Swirl vanes  32  are formed in one piece with the burner tip part  21  of the inner burner element  12 . The swirl vanes  32  are hollow and have in each case an interior space  58  which via a cooling fluid inlet opening  59  and a cooling fluid outlet opening  60  is fluidically connected to the flow passage  20  which leads around the displacement body  15 . The displacement-body interior space  58  is therefore part of the cooling circuit so that the swirl vanes  32  together with the inner burner tip part  21  are cooled by the cooling fluid. 
         [0049]    A tube  62 , which serves as a guide for inserting the pilot burner  22 , is also formed in one piece with the inner burner tip part  21  and the swirl vanes  32  in the present exemplary embodiment. Exemplary embodiments without a tube  62  for guiding the pilot burner  22  are also possible, however. The tube  62  which is shown in the figure therefore represents only one option. 
         [0050]    The structure of the pilot burner  22  in the region of the burner tip  1  is shown in  FIG. 4 . The pilot burner tip part  31  and the tubular section of the pilot burner  22  which is formed from the three inter-inserted tubes  24 ,  26 ,  28  can be seen in the figure. 
         [0051]    The pilot burner tip part  31  has a wall  31 A which is bent in an approximately U-shaped manner and encloses an interior space of the pilot burner tip part  31 . A displacement body  25  is arranged in the interior space. As in the case of the burner tip parts  11 ,  21  of the outer burner element  2  and of the inner burner element  12 , the displacement body  25  located in the interior space of the pilot burner tip part  21  is also of hollow design. It has a near end  66  pointing towards the end side  76  and a far end  68  facing away from this with a groove  25 A of fitting onto the center tube  26  of the tubular section of the burner element. Arranged in the region of the far end  68 , especially directly in front of the groove  25 A in the far end, is a displacement-body opening  70  via which the interior space  72  of the displacement body  25  is accessible. The displacement-body interior space  72  is enclosed by a wall  74  which via support structures  76 , for example the already described pillar-like or rib-like structures, is connected to the inner side of the burner-tip wall  31 A. Also in the case of the burner-tip wall of the pilot burner, the support structures  76  can be of a flow-guiding design. In any case, however, they are designed so that they do not obstruct the flow through the flow passage  30  which is formed between the outer side of the displacement body and the inner side of the burner-tip wall  31 A. 
         [0052]    The two ends of the wall  31 A—which is bent in an approximately U-shaped manner—of the pilot burner tip part  31  are connected to the outer tube  24  and to the inner tube  28  of the tubular section of the pilot burner  22 , and the displacement-body wall  74  is connected to the center tube  26  of the tubular section. The connection is constructed in this case at a point of the displacement-body wall  74  which is selected in such a way that the displacement-body opening  70  is open towards the feed passage which is formed between the outer tube  24  of the tubular section of the pilot burner  22  and its center tube  26 . The displacement-body interior space  72  is consequently integrated into the cooling fluid circuit. 
         [0053]    The outside diameter of the pilot burner  22  is selected so that it can be inserted into the tube  62  of the inner burner element  12 . The pilot burner  22  also encloses a largely cylindrical interior space in which an ignition burner and a flame monitoring device can be arranged. 
         [0054]    Both in the case of the outer burner element  2  and the inner burner element  12  and in the case of the pilot burner  22 , the burner tip parts  11 ,  21 ,  31  are produced separately in each case from the tubular sections which are formed by the inter-inserted tubes. Subsequently, the inter-inserted tubes are then connected to the respective burner tip parts by means of a welding process, for example. 
         [0055]    The burner tip parts can especially be produced in one piece in each case by means of an additive manufacturing process. As a result, the described complex structures, in which hollow displacement bodies are connected to the burner-tip walls via support structures, are made possible. In particular, the one-piece production of the swirl vanes  32  and the tube  62  with the inner burner tip part  21  can also be ensured by the additive production by means of an additive manufacturing process  5 . As an additive manufacturing process, especially selective laser sintering can be applied. 
         [0056]    A modification of the exemplary embodiment shown in  FIG. 3  is described below with reference to  FIG. 5 . The modification is concentrated in the main upon the embodiment of the displacement body and its interior space. The remaining elements of the exemplary embodiment described in  FIG. 3 , such as the swirl vanes, are therefore not shown in  FIG. 5 . Elements which correspond to those from  FIG. 3  are identified by the same designations as in  FIG. 3  and are not explained again in order to avoid repetitions. 
         [0057]    The displacement body of the exemplary embodiment shown in  FIG. 5  differs from the displacement body of the exemplary embodiment shown in  FIG. 3  mainly by the fact that its opening  50  is enlarged. Furthermore, a flow guiding element  80  projects from the inner side for the inner burner wall into the displacement-body opening  50  so that the flow guiding element  80  divides the opening into an inflow section  81  and an outflow section  82 . 
         [0058]    A flow path  83  is formed around the flow guiding element  80 . 
         [0059]    At the end of the flow guiding element  80 , the flow through the flow path  83  experiences a flow reversal  84 . In the region of the flow reversal  84 , a collecting chamber  85  branches from the flow path  83 , wherein the access to the collecting chamber is arranged in approximately the original flow direction, that is to say the flow direction before the flow reversal. Suspended particles present in the cooling fluid are not able to reproduce the abrupt direction change, on account of their inertia, during the flow reversal as easily as the fluid itself so that the suspended particles make their way into the collecting chamber  85  and can be deposited there. In this way, some of the suspended particles can be removed from the fluid before flow passes through the flow passage  20  which is formed between the outer side of the displacement body and the inner side of the burner-tip wall  21 A, as a result of which deposits of suspended particles in this flow passage can be reduced so that a constriction of the flow passage can be avoided or at least delayed. 
         [0060]    Although the exemplary embodiment with the collecting chamber  85  has been described with regard to the burner-tip part  21  of the inner burner element  12 , a corresponding embodiment can also be provided in the case of the burner tip part  11  of the outer burner element  2  and also in the case of the pilot burner tip part  31 . 
         [0061]    A further alternative to the exemplary embodiment from  FIG. 3  is shown in  FIG. 6 . Elements which correspond to those from  FIG. 3  are identified in this case by the same designations as in  FIG. 3  and are not explained again in order to avoid repetitions. As in  FIG. 5 , in  FIG. 6  the swirl vanes  32  and also the cylindrical tube  62  are not shown since these do not differ from the exemplary embodiment shown in  FIG. 3 . 
         [0062]    The essential difference to the exemplary embodiment shown in  FIG. 3  lies in the fact that the end wall  147  is of a thinner design than in the case of the exemplary embodiment shown in  FIG. 3 . In order to stabilize the thin end wall  147 , the density of support structures  146  is increased in its region. The support structures  146  are designed as pillar-like structures which converge to form arches on the displacement body  15 . In the present exemplary embodiment, the arches are designed as pointed arches so that the pillar-like support structures form a type of arch which has the shape of a gothic arch. 
         [0063]    Although in the exemplary embodiment shown in  FIG. 6  only the end wall  147  is of a thinner design, the thin wall can also extend beyond the end wall  147  and even form the entire burner-tip wall  21 A. By reducing the thickness of the burner-tip wall  21 A in thermally highly loaded regions a more rapid heat dissipation to the cooling fluid can be achieved. Furthermore, a thinner wall is less prone to heat fluctuations. 
         [0064]    The described pointed arch-like design of the support structures can be realized by means of the already mentioned additive manufacturing process. The design of the support structures and of the wall thickness described with reference to  FIG. 6  can also be realized in the case of the burner tip parts  11 ,  31  of the outer burner element  2  and of the pilot burner  22 . 
         [0065]    An alternative form of the support structures, which also enables a reduction of the wall thickness of the burner-tip wall, is shown in  FIGS. 7 and 8 . In this case,  FIG. 8  shows a section along the line VIII-VIII shown in  FIG. 7 . 
         [0066]    The support structures shown in  FIGS. 7 and 8  have the form of ribs  86  which are formed between the displacement-body wall  54  and the burner-tip wall  21 A and extend from the far end of the displacement body  15  around its near end and back towards the far end. In this case, the ribs  86  extend in parallel and converge to form arches both on the outer side of the displacement body and on the inner side of the burner wall. In the present exemplary embodiment, the arches are pointed arches so that between the individual ribs flow passages  20  are formed with cross sections which correspond to an ellipse running to a point at its ends. This design of the support structures also allows a reduction of the wall thickness with high stability of the thinner wall. The support structures described with reference to the  FIGS. 7 and 8  can be used in the case of the burner tip part  11  of the outer burner element  2  and/or the burner tip part  21  of the inner burner element  12  and/or the pilot burner tip part  31 . Although pointed arches have been described with reference to  FIGS. 7 and 8 , other arch shapes can also be used, wherein the respective arch shape inter alia can be selected with regard to the chosen production method. 
         [0067]    The present invention has been explained in detail based on specific exemplary embodiments for illustration purposes. In this case, elements of the individual exemplary embodiments can also be combined with each other. The invention is therefore not to be limited to individual exemplary embodiments but is only to experience a limitation as a result of the appended claims.