WO2004016987A1 - Pore burner and cooking appliance containing at least one pore burner - Google Patents

Abstract

The invention relates to a pore burner, especially for cooking appliances, comprising a housing provided with at least one inlet for a gas/air mixture as a fuel and/or at least one inlet for air and/or at least one inlet for gas and/or at least one outlet for air and/or gas and/or waste gases. Said housing comprises at least one dimensionally stable, porous moulded body consisting of sintered metallic powder and/or an especially pressed metallic wire mesh, on the surface of which and/or in the pore spaces of which are reaction zones for the flame development for forming a surface burner. The invention also relates to a pore burner comprising at least one distribution device for the targeted orientation of part of the gas and/or air flow and/or part of the gas/air mixture flow, said distribution device being at least partially arranged and/or moulded in the hollow body in such a way that part of the air and/or gas flow or part of the gas/air mixture flow can be distributed such that the inner wall of the hollow body, especially in the region of the distribution device, has a non-homogenous pressure distribution.

Description

 Pore burner and cooking appliance, containing at least one pore burner

description

The present invention relates to a pore burner, in particular for cooking appliances, comprising a housing having at least one inlet for a gas / air mixture as fuel and / or at least one inlet for air and / or at least one inlet for gas and / or at least one outlet for Having air and / or gas and / or exhaust gases, and a cooking appliance, containing at least one pore burner.

Furthermore, the invention relates to a pore burner system and the use of pore burners and pore burner systems for heat and / or steam generation in cooking appliances and heaters, and finally this cooking and heating appliances.

Pore burners are well known to those skilled in the art. This is generally a burner with a given combustion chamber volume with spatially contiguous cavities, over which or in which a defined flame zone is formed. Embodiments of known pore burners are described, for example, in US Pat. No. 5,522,723, WO 95/01532, DE 199 39 951 A1 and DE 199 04 921 C2. With the help of pore burners, for example, the size of industrial as well as domestic steam or hot water boilers can be reduced, since the heat energy is emitted both by radiation and by heat conduction, whereby the convective portion of the heat transfer decreases. For example, DE 199 04 921 C2 describes a housing container which, in addition to a radiation heat exchanger and a convection heat exchanger, also comprises a porous burner which is suitable for heating liquids. In DE 198 04 267 AI there is a equipped with a pore burner large water boiler for the production of steam and / or hot water.

In particular, in compressed construction and high ambient temperatures is according to DE 199 39 951 AI a frequently occurring under these conditions flashback or poor flame stability, e.g. due to pressure fluctuations and negative pressure, thereby avoiding that the pore size of the pore burner increases in the flow direction. In this case, in a zone of the porous material for the pore size, a critical Peclet number must be maintained, above which the flame development takes place and below which it is suppressed. In a pore burner, as described in DE 199 39 951 AI, the reaction of the fuel / oxidant mixture takes place within the porous matrix. This porous matrix is preferably produced by beds of temperature-resistant ceramic balls or saddles. Packed beds according to DE 199 39 951 A1 accordingly have at least two zones of bulk material with different pore sizes. WO 95/01532 also addresses the problem of producing a stable flame at low temperature and low pollutant emission. This document can be seen to change the porosity of the pore burner along the combustion chamber such that the pore size increases in the direction of flow of the gas / air mixture from the inlet to the outlet. The porous material of the pore burner used is again obtained by bulk material, for example in the form of loosely layered grains, which are solidified in a sintering process. Finally, basic embodiments of pore burner technology are described in EP 0 840 061 A1 and in DE-OS 2 211 297.

In the pore burners previously described, known from the prior art, the reactions underlying the flame formation between the fuel gas and the oxidizing agent regularly or predominantly take place within the porous matrix. Accordingly, the hot reaction products flow out of the combustion cavities without flame formation. This procedure entails that the flames are cooled by the burner material, which helps prevent further flame propagation and flashback. However, if the burner masses and the burner loads are very small, it may still come to a flashback. This is the case regularly, for example, when high temperatures are present even in the combustion chamber in compact heaters due to high ambient temperatures. A flashback can then often only achieve a sufficient flame cooling. However, this requires a large mass with high heat capacity and good thermal conductivity. The described pore burner devices also have in common that optimized gas homogenization and gas distribution over the burner surface as well as sufficient flame stability and dimensional stability of the surface are generally only possible by using a plurality of components of different geometries and / or materials.

Suitable flat flame burners based on pore burners have hitherto been known only in the form of sintered disks, for example as flat-flame burners of the so-called "Kaskan type" (according to WE Kaskan, "The dependence of fiame temperature on mass burning velocity", 6 ^th Symp on Combustion, The Williams & Wilkins Company, Baltimore, 1956, pages 134-143).

A high degree of flame stability, the prevention of flashback and the guarantee of a uniform and constant flame front in a flat flame burner can be regularly obtained only with a porous material of high homogeneity, otherwise a generally uneven flow profile results. However, a porous matrix with sufficiently high homogeneity can usually only be realized up to a predetermined component size. For larger sized burner systems are therefore regularly compromise on a uniform flow profile and the associated properties to take into account.

Conventional vollvormischende burners, especially surface burners or flat flame burner, are so far generally constructed of sheets, which are provided with hole and / or slit patterns, for example, as known from burners in cylindrical Brennkammem. For an approximately homogeneous distribution of the gas mixture it also requires further sheets with a coarser perforation, which are located below the aforementioned sheets. It is only under these structural specifications that it is first possible to adjust the flow velocities in such a way that the respective gas / air mixture can be supplied in suitable quantity to each point. Known surface burners may also consist of a flexible wire mesh fastened to a support structure, perforated ceramics or wire mesh. However, gas homogenization and gas distribution as well as flame stability and form stability are required. The quality of the surface also always combines a number of components made of different geometries and materials.

In general, so far used for cooking appliances on conventional heating systems with electric or gas-powered heating elements. Improving the efficiency of such heating systems would help conserve natural energy resources and reduce pollutant emissions.

It would therefore be desirable to be able to resort to cooking appliances, which, regardless of their size, have a very energy-efficient and low-emission and therefore also eco-efficient heating system.

Currently available pore burners are also often characterized by the fact that when using fully premixed gas / air mixtures can be implemented very different compositions and very variable flow rates at low surface load. In particular, when a homogeneous gas mixture is used, one obtains very low exhaust emissions. However, it is also observed with these pore burners that when the burner is in the so-called cold state and the gas mixture used has only a very low energy content, e.g. with very high Lufitzahl and / or low calorific value of the fuel gas, ignition by spark ignition often fails. Even with the spark ignition under the previously described conditions, the energy introduced by the spark due to the desired stabilization of the reaction zone in the vicinity of the porous material is often sufficient only for a local ignition of the gas mixture. Released heat of reaction is absorbed by the surrounding material, whereby the gas mixture in the ignition zone is deprived of energy and the chain branching reactions required for flame formation are prevented.

Although the above disadvantages can be more or less avoided by using a strong ignition coil with high ignition energy, a high ignition frequency and / or the simultaneous use of multiple ignition electrodes, however, these measures require additional space and cause additional costs, whereby the original advantage of pore burners relativized again becomes. The same is true when replacing ignition coils or ignition electrodes a permanent ignition by means of a glow or Zündbrenners is provided.

The present invention was thus based on the object of making pore burners accessible in particular for cooking appliances or further developing the generic pore burners such that they are no longer subject to the disadvantages of generic pore burners and, in particular, a high degree of flame stability and homogeneity, in particular also Design as surface burner or flat flame burner, grouting. Accordingly, the present invention further has the object of further developing generic cooking devices such that they can be eco-efficiently and constantly heated with a high energy efficiency with the lowest possible operating costs. Finally, the present invention has the object to provide a pore burner available that ensures reliable, improved ignition regardless of the energy content of the fuel mixture or the condition of the pore burner and helps to avoid delayed ignition.

This object is achieved by pore burner with a housing having sintered metal powder and / or, in particular pressed, Metalldrahtgestrick in the form of at least one dimensionally stable, porous shaped body, on the surface and / or in the pore spaces reaction zones of the flame development to form a surface burner. Accordingly, even the entire shaped body surface as such, due to the porous structure, the outlet, the pore burner according to the invention, optionally also without a defined, large-area outlet, z. B. at one end of the housing. The pore burner according to the invention regularly has at least one inlet for a gas / air mixture as fuel. In addition or alternatively, the pore burner or the housing of the porous burner may have at least one further inlet for air and / or a further inlet for gas. For example, separately supplied air can be used as secondary air or for cooling components of the pore burner. Preferably, so-called fully premixing burner systems, in particular also in cooking appliances, are used.

The pore burner according to the invention can be used, for example, for generating heat and / or steam in cooking appliances, in particular gas-fired cooking appliances, and furthermore also in heaters such as boilers or gas heaters, eg in building services, especially when using cylindrical Brennkammem.

The e.g. Porous burners according to the invention which are used in cooking appliances may be partially pre-mixing and, in particular, fully premixed pore burners. Here, the burner may be e.g. represent a, in particular cylindrical, tube, which is preferably closed at its end. Has proven particularly well the attachment of distributed on the circumference of the tube present gas outlet openings.

It can be inventively provided that the shaped body is essentially a hollow body, in particular a hollow cylinder. Suitable hollow bodies may further have any geometric shapes, e.g. represent in cross section an ellipse, a triangle, a square, a rectangle or any polygon. Suitable hollow bodies can also completely dispense with a defined, large-area outlet opening and, e.g. be designed as an ellipse, sphere or cylinder with only at least one defined opening for the inlet of the gas / air mixture. The use of hollow bodies makes it possible in a simple manner to create the largest possible surface area for a uniform flame front.

It has proved to be very advantageous that pore burners are accessible, in which the molded body comprises at least one mounting and / or fastening element, in particular a groove, a spring, a flange and / or a thread. Holding and fastening elements can thus be integrated with the pore burners according to the invention already in the dimensionally stable shaped body, for example of pressed metal wire knit, whereby the manufacturing cost of the pore burner according to the invention can be reduced and a production is much easier to implement for mass production. Of course, the dimensionally stable shaped body can also be easily welded for attachment, for example to the tube for supplying the fuel mixture. This can be accomplished particularly easily if both the tube and the dimensionally stable shaped body have matching cross sections and, for example, the shaped body is of cylindrical design and the tube has a circular cross section. Particular advantages in terms of handling and minimization of the components result from the fact that the mounting and fastening means is incorporated directly into the porous molding material of the pore burner. For example, a thread can be screwed into the pore body. Consequently, there is no need for additional mounting or fastening means and no connection technology for coupling the same to the pore burner.

According to a further aspect of the invention pore burners are present, comprising at least two, at least partially positively fitting abutting moldings, which are in particular partially, preferably joined together to form a groove. By combining dimensionally stable shaped bodies in a form-fitting manner, it is also possible, for example, to realize large-sized pore burners without having to accept losses with regard to a uniform gas passage or a uniform flow profile. Two or more joined moldings can form a stable connection via a phase or a groove. It is particularly advantageous if the adjacent moldings, for example via groove / spring structures, flush and firmly connected to each other or can be plugged into each other, without the need for additional fasteners. However, it may be necessary to permanently attach coupled molded body elements to one another by means of spot welds. The molded bodies are preferably connected to each other only at very few abutting points and thus secured against loosening. A constant material density is thus largely retained in the region of the joints, whereby a uniform flow profile is ensured. Insofar as in the case of very large molded articles of the type described above, a high homogeneity of the porous material and therefore also a flow profile which is as uniform as possible can not always be maintained, pore burners of a larger design which are accessible over the entire burner surface area are also accessible with the embodiment described above extremely uniform flow profile. In a preferred embodiment, the dimensionally stable molded bodies, in particular hollow bodies, are formed at their respective end regions or top surfaces such that they correspond in shape with one another, so that, for example, the front region of a molded body fits as precisely as possible into the rear region of another molded body , in particular of such an identical type, inserts. This makes it possible to obtain pore burners which are arbitrarily extendible in length, but without sacrificing homogeneity. _, Thus, has been found to be particularly advantageous that the porous burner according to the invention can be converted as such in a stable form or present in a stable form, which is configured such that two or more such porous burner to be used for connecting. For example, adjacent pore burner segments to be connected to one another may be configured at their sections to be coupled in such a way that they can be put on one another without the need for further fastening means. According to one embodiment, for example, the open end section of a pore burner segment can be equipped with at least one groove, which can be accurately connected to an end section of an adjacent pore burner segment provided with at least one spring. In this case, the dimensional stability of the pore burners used is already achieved during their production via the sintering of metal powder and the pressing of metal wire knits, without the need for further mechanical support elements. Of course, it is possible not only to couple two pore burners via groove / spring elements which correspond to one another, but three or more pore burners or pore burner segments can be coupled to one another with the formation of a uniform pore burner via the aforementioned connection technique. The tail of this combined pore burner preferably has a closure, for example in the form of porous burner material, so that the pore burner has no outlet opening. A one-piece pore burner as well as a pore burner segment can be designed, for example, both cylindrically and conically. The same applies to a pore burner formed from several pore burner segments. In this case, the pore burner preferably tapers in the direction of the end thereof.

It can be inventively provided that the material densities of at least two adjoining Formköφern substantially match.

Furthermore, it has been found in this context as a preferred embodiment that the material density in the region of the junction of two joined moldings essentially corresponds to the material density of at least one of these Formköφer.

Another embodiment of the invention is characterized in that the surface of the molded body has at least one irregularity, in particular at least one indentation and / or elevation, which deviates from the base of the molded body. By Indentations and / or elevations, ie irregularities in the surface of the molded body is regularly prevented from forming a substantially two-dimensional reaction zone. Accordingly, preference is given to those surfaces which do not have a consistently uniform surface and therefore also, for example, structures which do not repeat uniformly over one another. For this purpose, it is usually already sufficient to use moldings, in particular hollow bodies, with different material thicknesses, in particular if these are based on sintered metal powder. In this way, it is already prevented that self-excited vibrations can occur at the burner surface. As such, the surface of dimensionally stable, in particular pressed, metal wire knits is generally sufficiently irregular in order to suppress the described resonance phenomena, but of course may also have different strengths.

Accordingly, an embodiment provides that the wall thickness of a molded body varies and in particular has at least two different thicknesses. The wall thickness of a hollow body accordingly does not have to be constant within the same in this embodiment.

Preferred pore burners in the context of the present invention are flat flame burners.

Particularly preferred pore burners are characterized in that the molded body at least in regions, in particular in the region of a metal wire knitted fabric, a pressed density in the range of about 2.5 to about 5 g / cm, in particular from about 2.8 to about 4.5 g / cm. Lower densities generally require lower fan powers because of lower pressure drops, whereas with higher densities more uniform reaction zones can be achieved. The pressed metal wire knits according to the invention, as well as the sintered metal powder moldings, as such already dimensionally stable and require, for example, neither for targeted mixture management nor for shaping any stabilizing elements, for example in the form of perforated sheets to deliver functional flat flame burner. Furthermore, such pore burners are advantageous in which the wire diameter of the metal wire knitted fabric is in the range from about 0.1 to about 0.4 mm, in particular from about 0.16 to about 0.28 mm. In addition to the compact density, the porosity of the pore burners on the basis of pressed wire knit fabrics according to the invention can also be influenced by the wire thickness, ie the wire diameter, and / or the number of wires in the knitted fabric. For example, if the wire mesh only consists of a relatively thick wire, the pore burner generally has relatively large pores with a substantially matching pore size. If, for example, three wires with smaller diameters are used, for example, pores of different sizes are generally obtained with the same press density, but these are generally on average below the previously described embodiment.

Pore burners according to the invention comprising metal wire knits accordingly also advantageously have 1 to 5, in particular 1, 2 or 3, metal wires.

In this case, it can be provided according to the invention that the metal wire knit is present in axial or radial wound prior to the loading.

Furthermore, pore burners according to the present invention are preferred with which surface loads in the range from 20 to 300 W / cm, in particular from 30 to 260 W / cm, are accessible. Accordingly, in the pore burners of the present invention, even at 200 W / cm and more, the flame does not decrease. The maximum surface load is often not limited by the wire mesh, but by the flow rate of the air and / or gas supply. The surface load lower limit is regularly formed by extinguishing the flame as a result of high heat conduction by the application to the metallic surface. With a three-filament metal mesh based on a heat-resistant steel, for example, 1.4828, with a compact density of about 3.8 g / m, for example, surface loads in the range of about 30 to 160 W / cm can be readily realized. Thus, the pore burner according to the invention allows a very wide range of possible operating states between the flame extinguishing on the one hand and the Flammenabheben other hand, and thus a power modulation range of 1: 5 and more. For example, at a surface load of about 70 W / cm with an air ratio of about λ = 1.2, a glowing wire mesh is obtained. With a decrease in the air ratio, the glow will be used at higher powers, at higher air speeds, the surface radiates only at very low power. With With increasing intensity of annealing, the proportion of heat transported by radiation from the reaction zone becomes larger and larger. i

In a further embodiment according to the invention, it is provided that the metal powder and / or the metal wire mesh comprise or comprise at least one metal and / or metal alloy which forms an oxide layer, in particular a metal alloy containing chromium and / or aluminum. Suitable metals and metal alloys for the metal powders to be sintered and in particular for the wire knits are preferably heat-resistant materials, for example heat-resistant steels. These include z. High alloy steels such as low-carbon austenitic chromium, nickel and manganese steels. As an example, reference is made to the heat-resistant steel 1.4828 (XI 5 CrNiSi 20-12). Also well suited are those metals or metal alloys that can form an oxide layer on their surface, whereby the molded body can be equipped with a protective layer. Particularly suitable metal alloys have aluminum or / and chrome components or are composed of these metals. A suitable material provides z. B. the alloy with the material lobster 1.4767 (CrAl 20 5) and the alloys with the material number 1.47675 represents.

The object underlying the invention is achieved according to a further aspect by a pore burner, which has at least one distributor device for targeted alignment of a portion of the gas and / or air stream and / or the gas / air mixture stream, the at least partially in Hohlköφer the pore burner so arranged and / or ausformbar is that a part of the air and / or gas stream or the gas / air mixture stream can be distributed in such a way that the inner wall of the Hohlköφers, in particular in the region of the distributor undergoes an inhomogeneous pressure distribution.

While in conventional pore burner cavities, the gas / air mixture enters the cavity substantially uniformly, the apparatus of the invention succeeds in diverting a portion of the gas / air mixture stream selectively to a region of the inner wall of the pore burner hollow body. This selected area on the inner wall, the gas / air mixture is supplied with a greater pressure than surrounding areas of the Hohlköφers. In a preferred embodiment it is provided that the distribution device is a guide plate.

%

It can also be provided that the distribution device comprises essentially metallic and / or ceramic materials and is made for example of stainless steel.

The distribution device may e.g. in the form of a plate or a three-dimensional structure, z. As a wedge, at least partially present in the Hohlköφer, as long as it is ensured that the entering into the Hohlköφer gas is proportionately deflected to a region of the inner wall of the Hohlköφers. The distributor may be e.g. around an oblique, i. at an angle in the Hohlköφer protruding, arbitrarily shaped Ablenkbzw. Act deflection structure. Of course, the distribution device, in particular the baffle, not only have a flat deflection or deflection, but be arbitrarily shaped, provided that the attachment and / or shape of the distribution device allows a partial deflection, as shown above, of the incoming fuel gas. For example, the distributor or the baffle may have a round, oval or angular cross-section. In principle, the cross-sectional shape of the distributor device can always be readily adapted to the cross-sectional shape of the porous burner body. Furthermore, the distribution device or the guide plate can be kinked, annular, stepped or curved.

In a further embodiment has proved to be advantageous if the distributor or the baffle has at least one passage or an opening. Through the use of such perforated distribution devices can be particularly effective on the amount of gas to be diverted influence and ensure that always reaches a sufficient amount of combustion gas in the following on the distribution device residual portion of the Hohlköφers of the pore burner, so that the entire pore space or its surface for a flame can be used.

According to a particularly preferred embodiment, the size of the passages in the distribution device, in particular during pore burner operation, can be varied. In this way it is possible, for example, to respond immediately to changes in the composition of the fuel mixture to ensure a continuous, consistent flame formation over the entire pore burner. The pore burners according to the invention can furthermore have at least one burner tube for air and / or gas, which can be connected to an inlet of the pore burner. This burner tube is generally part of the supply line.

The distribution device may be present in sections in the hollow body, as well as in the burner tube, or in each case be completely present or mounted in the same.

It can be provided that the distribution device is at least partially attachable to the burner tube and / or the Hohlköφer. In general, it is sufficient if the distributor is attached via one or two welds on the inside of the burner tube.

It has proved to be advantageous if the distributor has no direct connection with the Hohlköφer.

A further advantageous embodiment is characterized in that the deflection surface of the distribution device, in particular of the guide plate, relative to the central axis of the Hohlköφers, in particular the hollow cylinder, is inclined.

Basically, even a slight inclination e.g. of the baffle with respect to the central axis of the hollow body to a selected area on the Innefläche the Porenbrennerhohlköφers preferred, d. H. to supply with a higher pressure with the fuel mixture. Be particularly advantageous tilt angles in the range of 10 to 45 °, in particular from 15 to 30 °, proved. Of course, the distribution device may also have a blade shape or be configured bent.

Optimal results are obtained regularly when the maximum cross-sectional area of the distributor in the direction of flow of the gas / air mixture is more than 50%, preferably 55 to 75%, of the cross-sectional area of the hollow body in the region of the distributor. Suitably, sufficient fuel gas should always pass the edges of the distributor and / or pass through openings in the latter into the sections of the pore burner hollow body following the distributor device.

A further embodiment of the invention has pore burner systems for the subject, the at least one pore burner according to the invention and at least one feed tube for Air and / or gas, which is connectable to an inlet of the pore burner, and / or at least one ignition device comprises. f

It can be inventively provided that at least one inlet of a dimensionally stable Formköφers via a mounting and / or a fastener, in particular a flange and / or thread, with at least one supply pipe and / or burner tube for air and / or gas is connected.

Furthermore, it can be provided according to the invention that at least one inlet of a dimensionally stable Formköφers is at least partially welded to at least one supply pipe and / or burner tube for air and / or gas.

In this case, according to the invention it can further be provided that the ignition device is arranged in the region of the outside of the hollow body in the region on whose corresponding inner side the distributor device has the smallest distance. Accordingly, the igniter, e.g. Ignition electrode, preferably in front of where the redirected fuel gas mixture exits the Porenbrennerwandung so that regularly with the first spark the flame is ignited. After that, the reaction front spreads steadily.

According to a further aspect of the present invention, the object is further solved by a cooking appliance, in particular a gas-fired cooking appliance containing at least one pore burner, in particular a pore burner according to the invention or a pore burner system according to the invention. As cooking appliances are those with closed as well as open systems into consideration. Preference is given to gas-fired cooking appliances, in particular those with a pore burner, which acts as a surface burner or flat flame burner, resorted to. It can Kleinstgargeräte, eg Küchengargeräte, as well with pore burners, in particular pore burners according to the invention, be equipped as large-scale cooking appliances, for example, used in commercial kitchens. Suitable fields of use for the pore burners according to the invention are, for example, steam cooking appliances or so-called combi steamers. With the pore burners according to the invention a very high degree of flame stability is achieved. At the same time, flashback is substantially completely prevented. Accordingly, pore burners are provided with a porous material of high homogeneity and uniform flow profile, which as a surface burner continuously have a uniform and constant flame front and are particularly suitable as a flat flame burner. With the pore burners of the invention, a quasi-two-dimensional, flat flame is maintained over the entire burner surface. The cooking devices according to the invention have a very high efficiency and can be extremely eco-efficient, so for example, resource-saving and low emission, operate. The heat input is very uniform and can also be regulated and controlled in a direct and simple manner. Surprisingly, the properties described above can also be realized with cooking devices according to the invention, which are small in size. Thus, the cooking devices according to the invention can be used both in commercial kitchens, eg for canteen operation, as well as in restaurants and restaurants. Gargeräte with housed surface burners are thus readily available.

Furthermore, the present invention was based on the surprising finding that at least a portion of the introduced or injected gas / air mixture is selectively supplied to a specific area of the inner wall of this Hohlköφers using a mounted in the interior of a Porenbrennerhohlköφers distribution or guide device. In this way can be reliably achieve a supply of fuel, which is always sufficient to be ignited with a spark. In particular, pore burners can be ignited properly regardless of their initial state and regardless of the quality of the gas / air mixture. By the gas / air mixture predominantly passes out within a defined range through the porous Hohlköφer, already can be started and maintained over a conventional ignition device which is mounted in the region of the preferred fuel outlet, the reaction. Already by this structurally little expensive measure the pore burner according to the invention works flawlessly and reliably under a variety of reaction conditions. Another advantage is that no compromises have to be made with regard to the compact design of pore burners. So it is of particular advantage that the distance between the surface of the pore burner and the Brennkammerumgrenzung can be kept very low. This was not easy to achieve with conventional burner types, since a reduction in distance is always accompanied by increased flow velocities, which have hitherto frequently increased . have led to extinguishment of the flames. In addition, a consistently high level of I ⁷ lameness stability is achieved as well as flame retardation substantially completely prevented.

Further features and advantages of the invention will become apparent from the following description in which preferred embodiments of the invention by way of example with reference to schematic drawings will be explained in detail. Showing:

Figure 1 shows the schematic structure of a cooking appliance according to the invention, comprising a pore burner;

Figure 2 shows a hollow cylindrical pore burner in cross section;

Figure 3 is a schematic perspective view of a pore burner according to the invention;

Figure 4 is a schematic cross-sectional drawing of the porous burner according to Figure 3; and

FIG. 5 shows a further schematic cross-sectional view of the pore burner according to FIG

Third

The cooking appliance 1 shown in Figure 1 comprises an interior 2 with a pore burner 4 according to the invention for the production of hot air. Alternatively or additionally, with the pore burner 4 or another pore burner (not shown) on the other hand also steam can be generated. For monitoring the burner function, each pore burner 4 comprises a sensor, not shown, in the form of an ionization current sensor and in each case an ignition device, not shown. The pore burner 4 is supplied with fuel gas or a fuel gas mixture via a supply line 6 with the interposition of a first gas valve (not shown). This gas valve assumes the functions of pressure control, quantity adjustment and, if necessary, gas filtration. The pore burner 4 is formed as a hollow cylinder and has at one end via a thread which is integrally integrated in the forming the Porenköφer body (not shown). About this thread, the in , the present embodiment as a pressed wire mesh present dimensionally stable

'Formköφer 7 are bolted directly to a base 8, which already a safe

Connection with the supply line 6 is ensured without further components are needed, which also makes it possible to exchange different pore burner 4 or Formköφer 7 in a simple and straightforward way against each other.

FIG. 2 shows a schematic representation of a porous burner 4 'in cross-section. The wall 10 of the hollow cylindrical Formköφers 7 'of the pore burner 4' has irregularities 12 and 14 in the surface 16 of the molded body, which goes back to a different thickness of Formköφernwandung 10. With pore burners designed in accordance with the invention, the phenomenon of combustion-induced, self-excited oscillations no longer occurs regularly. By the irregularities 12 and 14 of the Formköφers 7 'are formed as grooves that can interlock with each other, can be created with these Formköφern 7', which can form-fit together, larger-sized pore burner. In this case, the groove 12 engages a first Formköφers 7 'in the groove 14 of a second Formköφers 7', the free groove 12 in turn can be combined with the groove 14 of a third Formköφers 7 'under positive engagement.

3 shows an alternative pore burner system 3 'according to the invention comprising a pore burner 4 "according to the invention with a burner tube 24, a feed tube 26 connected thereto and a flange 28 which is connected directly to the feed tube 26. The flange 28 has a plurality of screw holes 34 For mounting in, for example, a cooking chamber of a cooking appliance or in the steam generator unit of a cooking appliance, a holder 36 for the ignition source 22 is also mounted on the flange 28. In the pore burner 4 ", which is designed in the form of a hollow cylinder, the baffle 100 protrudes into it. This baffle 100 is arranged such that it supplies at least a portion of the over the supply pipe 26 and the burner tube 24 into the interior of the pore burner 4 "reaching gas / air mixture targeted a defined region of the inner wall of the pore burner 4". For this purpose, it is already sufficient for the guide plate 100 to be inclined in the direction of the inner wall of this hollow cylinder with respect to the central axis of the hollow-cylindrical porous burner 4. For example, a substantially rectangularly shaped guide plate 100 may be slanted into the interior of the hollow cylinder, as shown in FIG By the baffle 100 also partially present in the burner tube 24 or there is attached, the gas / air mixture arriving via the supply pipe is channeled in parts at an early stage in the direction of the desired region of the inner wall of the pore burner. In this way, ignition in an early section of the pore burner body is completely unproblematic. In a preferred embodiment, the baffle 100 may also be arranged to be movable or rotatable within the hollow cylinder. For example, when using a high-energy gas / air mixture channeling of the same unnecessary, since it should not be expected ignition problems, so it would be advisable to align the baffle 100 parallel to the central axis of the hollow cylinder. By the proximity of the ignition source to the area on the outside of the pore burner 4 ", in which a particularly large amount of gas / air mixture exits, it is ensured in a simple manner and reliable manner that even a single spark is sufficient to start the combustion Of course, in another embodiment, the ignition source 22 mounted on the holder 36 may be rotatably mounted, so that it is to be brought to the outside of the pore burner 4 "only in the case of ignition.

4 shows a sectional view of the pore burner system 3 'or pore burner 4 "shown in FIG. 3. It can be seen here that the baffle 100 already begins in the burner tube 24 and extends into the interior of the pore burner 4". The guide plate 100 is accordingly preferably fastened in the region of the burner tube 24. The gas / air mixture introduced via the supply pipe 26 impinges on the guide plate 100 in the burner tube 24 and is diverted by it proportionately in the direction of an inner wall region of the porous burner 4 ".

3 shows a schematic cross-sectional side view of the pore burning system 3 'or pore burner 4 "according to FIG 3. Thereafter, the guide plate 100 is arranged inclined in the same direction both in the burner tube 24 and in the pore burner, for which a uniform angle, for example in the range of 20 to 25 ° C. As can be seen from FIGS. 4 and 5, the pore burner 4 "has a groove 18 incorporated in the pore burner material in the connection region with the burner tube, which is already sufficient to ensure a reliable connection to the burner tube 24 , Furthermore, it is also possible to incorporate into the pore burner material in the region of the outer wall a thread that leads to a mounted on the burner tube 24 mating thread to a secure connection. Already with the baffle 100 shown, accordingly, a gas mixture can be such that it comes to a localized pressure increase in the region of the inside of the pore burner present as Hohlköφer. This construction is also advantageous for maintaining a flame in a cold burner. Optionally, a fan to provide the gas mixture in the Porenbrennerhohlköφer or equip an existing fan with increased power, since the pressure losses are increased by the installation of a baffle in the rule.

The features of the invention disclosed in the foregoing description, in the drawings and in the claims may be essential both individually and in any combination for the realization of the invention in its various embodiments.

LIST OF REFERENCE NUMBERS

Cooking appliance

Interior of the cooking device, 3 'pore burner system, 4 4 "pore burner

Supply line, 7 dimensionally stable molded body

Threaded base 0 Wall of the hollow cylindrical shaped body 2, 14 irregularities or grooves of the molded body 6 Surface of the molded body 8 Groove 2 Ignition source 4 Burner tube 6 Feed tube 8 Flange 4 Screw holes 6 Bracket 00 baffle

Claims

 Expectations 1. pore burner, in particular for cooking appliances, with a housing which has at least one inlet for a gas / air mixture as fuel and / or at least one inlet for air and / or at least one inlet for gas and or at least one outlet for air and / or Has gas and / or exhaust gases, characterized in that the housing has sintered metal powder and / or, in particular pressed, metal wire mesh in the form of at least one dimensionally stable, porous molded body (1, 7 '), on the surface and / or in the pore spaces of which reaction zones Flame development to form a surface burner. 2. Pore burner according to claim 1, characterized by at least two, at least partially positively abutting, merged molded bodies, which are connected to one another in particular in regions, preferably with the formation of at least one groove or phase, and form a stable connection. 3. Pore burner according to claim 1 or 2, characterized in that the molded body (7, 7 ') comprises at least one integrated mounting and / or fastening element, in particular a flange and / or a thread (8). 4. Pore burner according to one of the preceding claims, characterized in that the molded body (7, 7 ') is essentially a hollow body, in particular a hollow cylinder. 5. Pore burner according to one of the preceding claims, characterized in that the molded body (7, 7 ') comprises at least one mounting and / or fastening element, in particular a groove, a spring, a flange and / or a thread (8). 6. Pore burner according to one of the preceding claims, characterized by at least two, at least in sections form-fittingly abutting one another, which are connected to one another in particular in regions, preferably with the formation of at least one groove. 7. pore burner according to claim 6, characterized in that the material densities of at least two abutting moldings substantially match. 8. pore burner according to claim 6 or 7, characterized in that the material density in the region of the connection point of two joined molded bodies essentially corresponds to the material density of at least one of these molded bodies. 9. pore burner according to one of the preceding claims, characterized in that the surface (16) of the molded body (7 ') has at least one irregularity (12, 14), in particular at least one indentation and / or elevation, which from the base of the molded body (7 ') deviates. 10. Pore burner according to one of the preceding claims, characterized in that the wall thickness of a molded body (7 ') varies, in particular has at least two different thicknesses. 11. Pore burner according to one of the preceding claims, characterized in that said pore burner is a flat flame burner. 12. Pore burner according to one of the preceding claims, characterized in that the molded body (7, 7 '), at least in some areas, in particular in the area of a metal wire knit, has a compression density in the range of approximately 2.5 to approximately 5 g / cm, in particular approximately 2.8 to about 4.5 g / cm ³ . 13. Pore burner according to one of the preceding claims, characterized in that the wire diameter of the metal wire knitted fabric is in the range from about 0.1 to about 0.4 mm, in particular from about 0.16 to about 0.28 mm. 14. Pore burner according to one of the preceding claims, characterized in that the metal wire mesh 1 to 5, in particular 1, 2 or 3, comprises metal wires. _, 15. Pore burner according to one of the preceding claims, characterized in that the metal wire mesh is present axially or radially wound before the pressurization. 16. Pore burner according to one of the preceding claims, characterized in that with said pore burner surface: nntlastungen in the range of 20 to 300 W / cm, in particular from 30 to 260 W / cm, are accessible. 17. Pore burner according to one of the preceding claims, characterized in that the metal powder and / or the metal wire mesh comprises or comprise at least one metal and / or a metal alloy which forms an oxide layer, in particular a metal alloy containing chromium and / or Aluminum. 18. Pore burner according to one of the preceding claims, characterized by at least one distribution device (100) for the targeted alignment of a part of the gas or air flow and / or the gas / air mixture flow, which can be arranged at least in sections in the hollow body of the pore burner (3 ') and / or it can be shaped that part of the air and / or gas flow or the gas / air mixture flow can be distributed in such a way that the inner wall of the hollow body, in particular in the region of the distribution device, experiences an inhomogeneous pressure distribution. 19. Pore burner according to claim 18, characterized in that the distribution device (100) is a baffle. 20. Pore burner according to claim 19, characterized in that the distribution device (100) comprises essentially metallic and / or ceramic materials. 21. Pore burner according to one of the preceding claims, characterized by at least one burner tube for air and / or gas, which can be connected to an inlet of the pore burner (3 '). 22. Pore burner according to one of claims 18 to 21, characterized in that the distribution device (100) is present in sections or completely in the hollow body and / or the burner tube. 23. Pore burner according to one of claims 18 to 22, characterized in that the distribution device can be attached at least in sections to the burner tube and / or the hollow body. 24. Pore burner according to one of claims 18 to 23, characterized in that the distribution device (100) has no direct connection to the hollow body. 25. Pore burner according to one of claims 18 to 24, characterized in that a deflecting surface of the distribution device, in particular the guide plate (100), is inclined with respect to the central axis of the hollow body, in particular hollow cylinder. 26. Pore burner according to one of claims 18 to 25, characterized in that the maximum cross-sectional area of the distribution device (100) in the direction of the flow direction of the gas / air mixture is more than 50% of the cross-sectional area of the hollow body in the region of the distribution device. 27. Pore burner system comprising a pore burner according to one of claims 1 to 26 and at least one supply pipe for air and / or gas which can be connected to an inlet of the pore burner, and / or at least one ignition device. 28. Pore burner system according to claim 27, characterized in that at least one inlet of a dimensionally stable molded body via a mounting and / or a fastening element, in particular a flange and / or a thread, with at least one feed pipe and / or burner pipe for air and / or gas connected is. 29. Pore burner system according to claim 27 or 28, characterized in that at least one inlet of a dimensionally stable molded body is at least partially welded onto at least one feed pipe and / or burner pipe for air and / or gas. , 30 Pore burner system according to one of claims 27 to 29, characterized in that the ignition device (22) is arranged in the area of the outside of the hollow body in the area to the corresponding inside of which the distribution device (100) is at the smallest distance. 31. Use of pore burners according to one of claims 1 to 26 or pore burner systems according to one of claims 27 to 30 for generating heat and / or steam in cooking appliances (1), in particular gas-heated cooking appliances, or in heating appliances. 32. Cooking appliance, in particular gas-heated cooking appliance, comprising at least one pore burner, in particular a pore burner (4, 4 ', 4 ") according to one of claims 1 to 26 or a pore burner system (3, 3') according to one of claims 27 to 30. 33. A heater comprising at least one pore burner, in particular a pore burner (4, 4 ') according to one of claims 1 to 26 or a pore burner system according to one of claims 27 to 30.