EP2687781A2 - Grid burners and method for monitoring the formation of a flame in a grid burner - Google Patents

Abstract

The surface burner (1) comprises a distribution plate (5) and a burner surface having knit fabric (3). The fuel-air mixture is fed from mixing chamber through the distribution plate to the burner surface. The distribution plate is provided with a control portion (4) and a main portion (6). The fuel-air mixture is passed through the knit fabric in the main section and unaffected in knit fabric in the control portion. An independent claim is included for method for monitoring of flame formation with surface burner.

Description

The invention relates to a surface burner according to the preamble of claim 1 and a method for monitoring flame formation in a surface burner according to claim 18.

Area burners are usually operated with gas, such as natural gas or biogas. Possible fuels but also liquid fuels such as fuel oil, ethanol or methanol into consideration. In this case, a gaseous fuel-air mixture is usually generated in a mixing chamber and passed through a perforated metal distributor plate to the burner surface, which may have a fiber knit, for example of metal fibers or a ceramic tile. The distributor plate serves for uniform distribution of the fuel-air mixture, which is burned at the side facing away from the distributor plate side of the fiber knitted fabric. On the fiber knit or on the burner surface so there is a flame area. The term fiber knit is here representative of any known type of flat fiber system or thread system and thus includes fiber materials or thread materials produced by knitting, knitting, crocheting, weaving, felting, walking and / or pressing. Because of the statistical distribution of the fibers, threads, meshes and / or pores, their geometry can not be produced reproducibly with the same precision as in other machining processes (for example, machining).

Such surface burners are used in particular in heaters and water heaters. With the aid of a monitoring electrode, for example an ionization electrode, a monitoring of the Combustion quality and in particular the level of oxygen content in the combustion mixture. Due to a high temperature of the flame, the combustion mixture is ionized and has a measurable conductivity, which is measured by means of the monitoring electrode and provided to a control unit. This is a regulation of the composition of the fuel-air mixture.

An oversupply of combustion air, so too much air in the fuel-air mixture, should be avoided, as this leads to a poor energy yield and thus to a reduced efficiency. A corresponding regulation is also known under the designation Luftzahlregelung or lambda regulation and is used, for example, in SCOT technology (system control technology). Theoretically, optimum combustion values are thus always achieved independently of the fuel condition, with adaptation of the surface burner to the respectively available fuel quality not being necessary.

However, hardly any clearly defined and locally reproducible flames can be generated in the case of surface burners with fiber knits (for example in the region of the monitoring electrode). A fiber knit is not completely uniform. Due to the non-reproducible knit geometry, there are no flames clearly defined in terms of flame geometry (flame pattern, length, shape, etc.) or combustion parameters (flame temperature, burnout rate, flame lift off or flame on the burner surface, etc.). Therefore, these values scatter relatively strongly across the burner surface. In addition, the fiber knit varies over the life and thereby additionally influences the formation of flames. Since the flame ionization fluctuates due to the dependencies set out above, accurate control of the air ratio and the residual oxygen content based on the ionization current flowing through the flame is hardly possible over a large modulation range.

In DE 10 2005 056 499 A1 It is proposed to reduce a flow rate of the fuel-air mixture in the monitoring area with respect to the main area in order to ensure sufficient flame monitoring even at different levels To ensure gas properties and operations, the monitoring electrode is assigned to the monitoring area.

In EP 0 339 499 A2 However, it is proposed to produce in the monitoring area flames with a greater length than in the main area, which is realized for example in that smaller outlet openings are provided in the distributor plate or the proportion of air in the fuel-air mixture is reduced. This is to ensure that the monitoring electrode is always available a flame useful for ionization measurement.

However, a scattering of flame formation is not completely eliminated by this measure. In particular, over a longer period, it can lead to a change in the flame image.
The invention has for its object to eliminate the disadvantages of the prior art and to achieve a defined flame formation in the surveillance area, so that in particular a precise air ratio control is possible.

According to the invention this object is achieved with the features of claim 1 and with the features of claim 18. Advantageous developments can be found in the dependent claims.

The surface burner according to the invention thus has a distributor plate with a monitoring area and a main area, wherein the fuel-air mixture in the main area flows through the first fiber knit and is unaffected in the monitoring area of the first fiber knit. The condition and shape of the first fiber knit fabric therefore have no effect on flame formation in the monitoring area. Rather, a flame formation in the monitoring area is independent of the first fiber knitted fabric. In the main area, the distributor plate is further protected by the first fiber knit especially from too high temperatures, so that the desired life of the surface burner can be achieved. Since flame formation is not influenced or disturbed by the first fiber knit in the monitoring area, it is possible to produce a geometrically well-defined flame. This creates defined flame conditions without scattering between different surface burners and without change over the life. The defined conditions allow precise control over a large modulation range.

In particular, a mixture outflow geometry which can be reproduced from burner to burner and thus reproducible flame parameters are created in the monitoring area on the monitoring electrode, which permit a reproducible ionization measurement from burner to burner and not age-dependent.

It is particularly preferred that the monitoring area is formed much smaller than the main area, wherein the monitoring area has a size of about 5 cm ² to 15 cm ² , in particular of about 10 cm ² . The surveillance area is for example 50 mm x 20 mm in size and accordingly very small compared to the main area. A heat conduction in the distributor plate from the monitoring area in the main area, which is protected by the first fiber knit and therefore has a lower temperature, is therefore easily possible, so that excessive overheating of the distributor plate in the monitoring area is not to be feared. It is often required in the monitoring area, a larger flow rate of the fuel-air mixture to produce a strong flame, which also means that the flame is not directly applied to the surface of the distributor plate, but without the additional first fiber knitted fabric of the distributor plate is spaced. This ensures that even at low load, a sufficiently strong flame is generated in the monitoring area in order to obtain a usable ionization signal. Overheating of the distributor plate is therefore not to be feared even at low power levels.

In order not to interrupt heat conduction paths from the monitoring area to the main area of the distributor plate, slot-shaped outlet openings can be provided in the distributor plate at least in the monitoring area, which run perpendicular to the respective nearest edge of the monitoring area. This ensures safe heat dissipation from the monitoring area to the main area.

In the monitoring area, the distributor plate can be made more permeable to the fuel-air mixture than in the main area. This can be realized, for example, by virtue of the fact that the sum of the open cross sections per area in the surveillance area is higher than in the main area. In particular, with a low required power so that a relatively strong flame in the monitoring area ensures that can be used to generate a sufficient ionization signal.

Additionally or alternatively, the distributor plate may have a greater thickness in the monitoring area than in the main area. For example, the distributor plate is made of a metal or stainless steel sheet having a thickness of about 0.6 mm. In the monitoring area, the thickness of the distributor plate is then increased to, for example, 1 mm or 1.5 mm. For this purpose, an additional metal sheet may be formed, for example, from stainless steel or a high-temperature-resistant alloy, such as a nickel-based alloy, which is welded to the distributor plate in the monitoring area. This further improves the dissipation of heat in the monitoring area. In this way, a secure positioning of the first fiber knitted fabric on the distributor plate is obtained, whereby it is ensured that the first fiber knitted fabric does not protrude into the monitoring region and thus influences the flame formation in the monitoring region. A weld is in a metal fiber knit a particularly simple way to fix the first fiber knit to the distributor plate. The welding takes place for example via individual welds.

In a preferred embodiment, the monitoring area is free of the first fiber knit. The generated flame image in the monitoring area is then essentially determined by the openings in the distributor plate. In this case, the burner surface in the monitoring area can be completely free, so the distributor plate are open, so that the flames are generated without the interposition of a burner medium in the monitoring area.

In a preferred embodiment, the distribution plate is covered in the monitoring area downstream of a second fiber knitted fabric, which has a lower flow resistance than the first fiber knitted fabric and forms part of the burner surface. The second fiber knit then causes a protection of Distribution plate in the monitoring area, but affects the flow of the fuel-air mixture but significantly lower than the first fiber knit. The first fiber knitted fabric can be produced from a proven, relatively thick metal fiber fabric, which is sold, for example, under the name NIT 100 SE from Bekaert Combustion Technology. In contrast, the second fiber knitted fabric is very thin, with a ratio of hidden areas to holes being very small, so that the fuel-air mixture can flow through the second fiber knitted fabric virtually undisturbed. Influencing the flame pattern is then essentially determined by the shape of the openings in the distributor plate and hardly influenced by the second fiber knit. As the second fiber knitted fabric, for example, a metal fiber knit fabric offered by Bekaert under the name NIT 100 A can be used. In particular, in an already stronger flow through the distributor plate in the monitoring area than in the main area overheating of the second fiber knit will not be to be feared, as in the monitoring area a slightly uplifting flame and increased cooling is obtained.

Advantageously, while the first fiber knit fabric is connected to the second fiber knit, in particular welded. This ensures that even during the transition from the monitoring area to the main area, the distributor plate is covered by a fiber knitted fabric so that local overheating can not occur. A welding of metal-fiber knits and different mesh sizes and thicknesses is easily possible and represents a particularly simple and durable connection.

In an alternative embodiment, the distribution plate in the monitoring area downstream of a perforated, temperature-resistant metal sheet is covered, which forms a part of the burner surface. The metal sheet is made, for example, from a high temperature resistant stainless steel alloy and perforated and / or perforated. Edges of the metal sheet close to the first fiber knit fabric or are covered by the first fiber knit, so that no thermally overloaded areas arise. The metal sheet protects the distribution plate in the monitored area. The distribution plate is, for example, at a distance of 1 mm to 3 mm to the distribution plate in the surveillance area arranged. The geometry of the perforation of the metal sheet can be produced with a very high repetition accuracy, so that a well-defined flame is obtained.

In this case, the metal sheet may be kept freely stretchable on the surface burner in a longitudinal direction. This is possible for example by a combination of a fixed bearing with a movable bearing, wherein the metal sheet is thus fixed only on one narrow side and is displaceably mounted on an opposite narrow side and / or on the adjacent longitudinal sides. As a result, the occurrence of temperature stresses due to different expansion behavior of the metal sheet relative to the distributor plate is avoided.

Preferably, the distributor plate is interrupted in the monitoring area. The size of this interrupt corresponds to the size of the monitored area. The flow of the fuel-air mixture is then not affected at all in the monitoring area by the distributor plate, but only by the metal sheet. Overall, this results in a very low flow resistance, so that even at low power levels, the formation of a strong flame in the monitored area is ensured.

In an alternative preferred embodiment, the first fiber knit is penetrated in the monitoring area of nozzles. As a result, the entire distributor plate can be covered by the first fiber knitted fabric and thus protected against overheating, while at the same time ensuring that the flow of the fuel-air mixture can not be influenced by the first fiber knitted fabric in the monitored area. Rather, the fuel-air mixture in the monitoring area with the aid of the nozzles is passed through the layer of the first fiber knitted fabric and on this fiber knit and can thus be used to generate a defined flame.

The nozzles can be used simultaneously to locally hold the first fiber knit, for example, to avoid sagging of the fiber knit, which can lead to an elongation of the fabric over the life. For the first fiber knit, for example, non-positively on the nozzles and / or held in a form-fitting manner. For this purpose, the fiber knit is pierced by the nozzles, so to speak, whereby loops of the fiber knit are stretched. Individual fibers of the fiber knitted fabric are thus not damaged. The nozzles can easily have a diameter of about 5 mm. Additionally or alternatively, the nozzles may also be welded or otherwise connected to the first fiber knit.

For a uniform distribution of the fuel-air mixture, the nozzles may each have a plurality of outlet channels. It is particularly preferred that the outlet channels extend at least partially at an angle greater than or equal to 0 ° and smaller than 90 ° to a nozzle longitudinal axis. This results in a lateral escape of the fuel-air mixture, so that the flame lifts less strongly from the burner surface. This is advantageous for accurate ionization measurement in the flame and thus for the adjustment and regulation of an air ratio (residual oxygen content).

Preferably, the nozzles are connected to the distributor plate, in particular welded or riveted. The position of the nozzles with respect to the distributor plate and the monitoring electrode is then clearly defined so that the nozzles can be used to position the fiber knit. It is also possible to form the nozzles in one piece with the distributor plate, wherein these are in particular deep-drawn. This ensures a smooth transition from the distributor plate into the nozzles, without the need for additional work steps.

The invention is also achieved by a method of monitoring flame formation in a surface burner by monitoring flame formation in a monitoring area, wherein a fuel-air mixture in the monitoring area is guided past a first fiber knit covering a main area. It can be provided that the monitoring area is kept free of fiber-fiber, so that the fuel-air mixture unhindered in the monitored area from the first fiber knit emerge from the distributor plate and can be used for geometrically defined flame formation. In the monitoring area, instead of the first fiber knitted fabric, other burner media such as a second fiber knit or a metal sheet can be used be arranged to support the distributor plate in the monitoring area and to ensure a defined flame formation. The features and advantages explained in connection with the surface burner thus also result in connection with the method.

Fig. 1

einen Flächenbrenner in räumlicher Darstellung;

Fig. 2

einen Flächenbrenner in Draufsicht;

Fig. 3

einen Flächenbrenner einer ersten Ausführungsform im Schnitt;

Fig. 4

einen Flächenbrenner einer zweiten Ausführungsform im Schnitt;

Fig. 5

einen Flächenbrenner einer weiteren Ausführungsform im Schnitt;

Fig. 6a

einen Flächenbrenner einer weiteren Ausführungsform im Schnitt;

Fig. 6b

den Flächenbrenner nach Fig. 6a im Betriebszustand;

Fig. 7

eine weitere Ausführungsform des Flächenbrenners im Schnitt;

Fig. 8

ein Detail des Flächenbrenners im Schnitt und

Fig. 9

eine Düse des Flächenbrenners in Schnittansicht.

In the drawings, embodiments of the invention are shown. Herein show:

Fig. 1

a surface burner in spatial representation;

Fig. 2

a surface burner in plan view;

Fig. 3

a surface burner of a first embodiment in section;

Fig. 4

a surface burner of a second embodiment in section;

Fig. 5

a surface burner of another embodiment in section;

Fig. 6a

a surface burner of another embodiment in section;

Fig. 6b

the surface burner after Fig. 6a in the operating condition;

Fig. 7

a further embodiment of the surface burner in section;

Fig. 8

a detail of the surface burner in section and

Fig. 9

a nozzle of the surface burner in a sectional view.

In FIG. 1 a surface burner 1 is shown in a spatial representation, which has a box-shaped burner frame 2, in which a mixing chamber is formed. The surface burner 1 has a first fiber knitted fabric 3, which is arranged between the sides of the burner frame 2. The first fiber knitted fabric 3 forms a burner surface.

A monitoring area 4 is free of the first fiber knitted fabric 3, so that a distributor plate 5 can be seen. The distributor plate 5 extends over the entire upper side of the surface burner 1 and is covered outside the monitoring region 4 in a main region 6 of the first fiber knit 3. In the distributor plate 5, slot-shaped outlet openings 7 are formed which in each case run perpendicular to the nearest edge 8 of the monitoring area 4. As a result, heat conduction paths, the heat from the monitoring area 4 in the main area. 6 transport, not interrupted by the outlet openings 7, so that a uniform and rapid heat dissipation can be done.

A fuel-air mixture, which is located in the mixing chamber within the burner frame 2, can flow through the distributor plate 5 to the burner surface above the first fiber knitted fabric 3 in the main region 6 and above the distributor plate 5 in the monitoring region 4. Thus, the fuel-air mixture reaches the side facing away from the distributor plate 5 top of the first fiber knit 3. There and directly above the distributor plate 5 in the monitoring area 4, the fuel-air mixture is ignited and then can form the flames.

In order to achieve a larger mixture volume throughput in the monitoring area 4 and thus to generate more vigorous flame formation, a plurality of and / or larger outlet openings 7 can be provided in the area of the monitoring area 4 of the distributor plate 5 than in the main area 6. This achieves that in the monitored area 4 raised flames lift off the distributor plate 5, so that it is not thermally overloaded. At the same time, the larger volume flow provides additional cooling.

At the edge 8, which represents a transition between the main area 6 and monitoring area 4, the first fiber knitted fabric 3, which is formed as a metal fiber knitted fabric, with the distributor plate 5, which may be formed for example as a perforated stainless steel sheet, welded. As a result, the first fiber knitted fabric 3 is stabilized on the one hand, and on the other hand it is ensured that no influence of the fuel-air mixture through the first fiber knitted fabric 3 can take place in the monitoring region 4. Independently of an aging of the first fiber knitted fabric 3, a defined flame can thus be generated in the monitoring area 4 and used for controlling the air number, that is to say residual oxygen monitoring.

In FIG. 1 is above the monitoring area 4 no fiber knit or other burner medium arranged. But it is also possible to cover the distributor plate 5 in the monitoring area 4 with a comparison with the first fiber knitted fabric 3 lighter and / or thinner second fiber knit 21 to the distributor plate. 5 also to protect in the monitoring area from thermal stress. The second fiber knit should then have a lower flow resistance than the first fiber knit 3. This embodiment is in Fig. 3 shown.

In FIG. 2 the surface burner 1 is shown in plan view. In this embodiment, the distributor plate 5 is covered in the monitoring area 4 by a metal sheet 9 having defined openings 10. The metal sheet 9 is formed as a perforated stainless steel sheet.

The first fiber knitted fabric 3 is welded at the edge 8 to the metal sheet 9. In addition, the first fiber knitted fabric 3 is welded to the burner frame 2 and so clearly positioned. In the monitoring area 4, the first fiber knitted fabric 3 can thus have no influence on the flame formation. Rather, the fuel-air mixture is passed through the metal sheet 9 and its openings 10, so that a defined flame can be generated.

Fig. 3 shows the area burner Fig. 1 in cross section. In the monitoring area 4, a second, much lighter and more permeable fiber fabric 21 is disposed of metal fibers than in the main area 6, so that the fuel-air mixture in the monitoring area is not or hardly affected. This generates a defined flame in the monitoring area.

Fig. 4 shows one opposite the representation in Fig. 3 only slightly modified embodiment in which the second fiber knitted fabric 21 is not formed as a metal fiber knitted fabric, but from another material. Incidentally, the in Fig. 4 surface burners shown in Fig. 3 shown embodiment.

FIG. 5 shows the embodiment according to FIG. 2 in cross section. The mixing chamber 11, which is surrounded by the burner frame 2, is covered on its upper side by the distributor plate 5. In the main area 6, the first fiber knitted fabric 3 is located on the distributor plate 5. In the monitoring area 4 is at a distance of about 1mm to 3mm above the distributor plate 5, the metal sheet 9. Here, the metal sheet 9 at its the burner frame 2 facing narrow side 12th freely slidably held on the burner frame 2 (floating bearing). At his opposite Narrow side 13, the metal sheet 9 is firmly connected to the distributor plate 5, so that a fixed bearing is formed. In the longitudinal direction, the metal sheet 9 can therefore expand freely, so that no thermal stresses occur.

A fuel-air mixture passes from the mixing chamber 11 through the outlet openings 7 of the distributor plate 5 and flows through the first fiber fabric 3 in the main region 6, so that 3 flames can be formed on a side facing away from the distributor plate 5 side of the first fiber knitted fabric. In the monitoring region 4, the fuel-air mixture flows through the openings 10 of the metal sheet 9, so that 9 forms a defined flame on a side facing away from the distributor plate 5 side of the metal sheet. The distributor plate 5 is thus protected in the main region 6 by the first fiber knitted fabric 3 and in the monitoring region 4 by the metal sheet 9 against thermal stress from the flames. Accordingly, the distributor plate 5 may be made relatively thin and, for example, have a thickness of 0.6 mm.

In the monitoring area 4, the outlet openings 7 are arranged at a smaller distance from one another than in the main area 6. As a result, the volume flow per unit area in the monitoring area 4 is greater than in the main area 6.

Outside the surface burner 1 and above the monitoring area 4, a monitoring electrode 14 is arranged, with which the conductivity of the burning ionized fuel-air mixture is detected. From this it is possible to determine the air ratio or the residual oxygen content and thus achieve an air ratio control. The monitoring electrode 14 is therefore also referred to as ionization electrode.

In FIG. 6a a further embodiment of the surface burner 1 is shown in cross section, which is largely according to the embodiments FIG. 3 and FIG. 5 equivalent. However, the distributor plate 5 in the monitoring area 4 has an interruption (recess) 15. The fuel-air mixture thus passes from the mixing chamber 11 through the interruption 15 directly to the metal sheet 9 and can escape through the openings 10. Accordingly, a flow resistance in the monitoring area 4 is very small and, in particular, significantly smaller than in the main area 6. This results, for example, in twice as large a flow and thus a lifting flame in the monitoring area 4, whereby a thermal load of the metal sheet 9 is kept low. At the same time a strong flame is ensured even if only a small power from the surface burner 1 is required and, accordingly, relatively little fuel-air mixture is supplied.

In Fig. 6b is the surface burner 1 shown in the operating state in which flames 22 are ignited at the burner surface by outflowing fuel-air mixture. In the monitoring area 4, a much more controlled, defined flame is formed than in the main area 6.

Incidentally, the surface burner corresponds to 1 in FIGS. 6a and 6b the embodiment according to FIG. 5 ,

In FIG. 7 a further embodiment of the surface burner 1 is shown in cross section, wherein the entire burner surface, so both the main area 6 and the monitoring area 4 is covered by the first fiber knit 3. So that in the monitoring area 4 no influence on the fuel-air mixture, 4 nozzles 16 are provided in the monitoring area, which penetrate the first fiber knit 3. For this purpose, stitches of the first fiber knitted fabric 3 are widened through the nozzles 16, whereby the first fiber knit fabric 3 is held on the nozzles 16 in a force-locking and / or form-fitting manner. The nozzles 16 are riveted into the distributor plate 5 and provide a fluid-conducting connection to the mixing chamber 11.

FIG. 8 shows an embodiment of the surface burner 1, wherein the nozzles 16 not as in the embodiment of FIG. 7 are riveted, but have been integrally formed by deep drawing from the distributor plate 5. This results in very favorable flow conditions. In order to obtain a secure fixation of the first fiber knitted fabric 3, in particular in the region of the monitoring area 4, so that the first fiber knit fabric 3 can not cover nozzle openings, the first fiber knit fabric 3 in the monitoring area 4 is welded to the distributor plate 5, with individual spot welds are sufficient.

FIG. 9 shows a sectional view of a preferred embodiment of the nozzle 16. The nozzle 16 has a lying on the longitudinal axis 17 outlet channel 18 and two lateral outlet channels 19, 20. This results in a very uniform distribution of the fuel-air mixture above the monitoring area 4 and thus a strong flame with light and reproducible from burner to burner ionization measurement.

Due to the inventive design of the surface burner 1, the fundamental problem of flame dispersion in the monitoring area 4, which is associated with a monitoring electrode 14, thereby avoided that an influence of the flow of the fuel-air mixture is prevented by the first fiber knit 3 by the first fiber knitted fabric 3 is cut out in this area. Instead, either no burner medium is placed in the monitoring area 4 at all, so that the flames are formed directly above the distributor plate, or burner media are used which provide lower flow resistance and / or more defined flow conditions than the first fiber knit 3. Accordingly, in the monitored area arranged either a lighter second fiber knitted fabric having a lower flow resistance, or a metal sheet with openings, which is not subject to aging such as the fiber knit and can be manufactured and assembled with high repeatability. In order to achieve a greater flow through the monitoring area with respect to the main area, the distributor plate 5 is provided in the region of the monitoring area with a larger number of outlet openings. It is also conceivable to interrupt the distributor plate in the region of the monitored area, ie to cut it out, for example.

By means of these refinements, it is achieved that the flame image in the monitoring area can be generated in a very defined manner. In this case, an uncooled surface of the distributor plate is kept very low in the monitoring area, so that a good heat dissipation can take place. It is thus obtained an exact definition of the outflow of the fuel-air mixture and thus generates a defined flame, which does not change over a longer period.

Claims (18)

Surface burner with a distributor plate and a burner surface having at least a first fiber knit, and with a mixing chamber, from which a fuel-air mixture is passed through the distributor plate to the burner surface, characterized in that the distributor plate has a monitoring area and a main area , wherein the fuel-air mixture in the main region flows through the first fiber knitted fabric and is unaffected in the monitoring area of the first fiber knitted fabric. Surface burner according to claim 1, characterized in that the monitoring area is formed much smaller than the main area, wherein the monitoring area has a size of in particular 5 cm ² to 15 cm ² , in particular of about 10 cm ² . Surface burner according to one of claims 1 or 2, characterized in that the distributor plate has slot-shaped outlet openings at least in the monitoring area, which run perpendicular to the respective nearest edge of the monitoring area. Surface burner according to one of claims 1 to 3, characterized in that the distributor plate is more permeable to the fuel-air mixture in the monitoring area than in the main area. Surface burner according to one of claims 1 to 4, characterized in that the distributor plate in the monitoring area has a greater thickness than in the main area. Surface burner according to one of claims 1 to 5, characterized in that the first fiber knitted fabric is fixed at a transition between the main area and monitoring area on the distributor plate, in particular welded. Surface burner according to one of claims 1 to 6, characterized in that the monitoring area is free of the first fiber knitted fabric. Surface burner according to one of claims 1 to 7, characterized in that the distributor plate is covered in the monitoring area of a second fiber knitted fabric having a lower flow resistance than the first fiber knitted fabric and forms a part of the burner surface. Surface burner according to claim 8, characterized in that the first fiber knitted fabric is connected to the second fiber knitted fabric, in particular welded. Surface burner according to one of claims 1 to 7, characterized in that the distributor plate is covered in the monitoring area with a perforated, temperature-resistant metal sheet forming part of the burner surface. Surface burner according to claim 10, characterized in that the metal sheet is held freely stretchable in a longitudinal direction. Surface burner according to claim 10 or 11, characterized in that the distributor plate is interrupted in the monitoring area. Surface burner according to one of claims 1 to 6, characterized in that the first fiber knitted fabric is penetrated in the monitoring area of nozzles. Surface burner according to claim 13, characterized in that the first fiber knitted fabric is held on the nozzles non-positively and / or positively. Surface burner according to claim 13 or 14, characterized in that the nozzles have outlet channels which extend at an angle greater than or equal to 0 ° and less than 90 ° to a nozzle longitudinal axis. Surface burner according to one of claims 13 to 15, characterized in that the nozzles are connected to the distributor plate, in particular welded or riveted. Surface burner according to one of claims 13 to 15, characterized in that the nozzles are formed integrally with the distributor plate, in particular deep-drawn. Method for monitoring flame formation in a surface burner, in particular according to one of the preceding claims, characterized in that flame formation is monitored in a monitoring area, in particular with a monitoring electrode, wherein a fuel-air mixture in the monitoring area on a first fiber knitted fabric which is a main area covered, passed by.

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