Burner Arrangement

Abstract

The invention relates to a burner arrangement comprising a burner plate (1) having a multiplicity of apertures (2) and a monitoring device for monitoring the formation of a combustion zone (3) extending from the burner plate (1), wherein the monitoring device comprises a cathode (5) provided on a flame-side top (4) of the burner plate (1) and an anode (7) arranged in the region of the combustion zone (3). To improve the thermal stability and thus the durability, provision is made according to the invention for the burner plate (1) to be made of a non-metallic material and for the cathode (5) to be arranged as a separately designed component in the region of the top (4) of the burner plate (1).

Description

The invention relates to a burner arrangement as defined in the preamble of claim 1.

Such a burner arrangement is generally known in accordance with the state of technology. In particular, gas burners are equipped with a nozzle or burner plate made of metal. During operation of the gas burner, a gas flowing through the nozzles is burnt. In this connection, flames extend from a top side of the burner plate. During operation, it can happen, among other things, that the flames are extinguished by a gust of wind, for example. In this case, gas would escape through the nozzles. In a closed room, for example, this can create an explosive mixture of gas and air. To avoid this, a monitoring unit is provided on the burner plate to monitor the extinguishment of the flames extending from the burner plate. In the monitoring unit, the metallic burner plate serves as the cathode. An anode is provided above the cathode in the area of the flames. The extinguishment of a flame can be detected based on a significant change in the electrical conductivity between the cathode and the anode and, as a result of this, a safety shutoff valve installed in a gas feeder line can be closed. Such gas burners which burn the gas by creating an open flame do not make optimal combustion possible, among other things.

From DE 43 22 109 A1 a so-called gas pore burner is known. In this connection, the gas is burned in a volume burner element made of porous ceramic. The suggested gas pore burner makes possible particularly clean combustion. Due to the provision of a volume burner element, an undesirable breakdown of the combustion reaction will almost never occur during operation.

However, also with such a gas pore burner the undesirable escape of combustible gas is still possible, for example, due to a defective ignition unit.

The object of the invention is to eliminate the disadvantages as per the state of technology. In particular, a burner arrangement is to be specified which makes low-pollution combustion possible and, at the same time, the quick and reliable detection of the undesired escape of unburnt fuel.

This object is solved by the features of claim 1. Useful embodiments of the invention result from the features of claims 2 to 12.

According to the provisions of the invention, it is provided that the burner plate is made from a non-metallic material and the cathode is located as a separately formed component in the area of the top side of the burner plate.

Due to the use of a non-metallic material, a ceramic material for example, to make the burner plate, the temperature resistance and thus the durability of such a formed burner arrangement is improved. The provision of a cathode designed as a separate component makes possible the creation of the monitoring unit to monitor the formation of a combustion zone extending from the burner plate. The suggested burner arrangement makes possible quick and reliable detection of the extinguishment of a flame, a faulty ignition or similar. The suggested burner arrangement is suitable for the implementation of both surface and volume burners. Such burners make particularly clean fuel combustion possible. The term “fuel” is understood to mean in particular gaseous fuels, for example combustible gases, vaporized liquid fuels, for example mixtures of vaporized oil and air, alcohol/air mixtures and similar.

According to an advantageous embodiment, it is provided that a volume burner body with a combustion-enabling, communicating pore area is located opposite the top side. The provision of such a volume burner body makes possible a simple and inexpensive way to make a volume burner. In this case, the combustion of the fuel occurs essentially within the volume burner body. In this connection, a slit with a specified width can be provided between the top side and a bottom side of the volume burner body. The width of the slit is usefully 0.5 to 15 mm, preferably 1 to 5 mm. The provision of the suggested slit simplifies ignition.

According to a further advantageous embodiment, the volume burner body and/or the burner plate is/are made of a ceramic material. In this connection, this can be porous ceramic, a perforated plate, a ceramic foam or similar.

According to a useful embodiment, the cathode is located in the slit. It can lie on the top side, for example. But it is considered as particularly advantageous when the cathode is contained in a recess which opens towards the top side of the burner plate. In this case, an undesirable strong heating up of the cathode during the operation of the burner arrangement is avoided. This makes possible a particularly precise detection of a malfunction.

It is useful that at least some of the breakthroughs provided in the burner plate open in the recess. Due to this, the cathode contained in the recess is surrounded by still unburnt gas and thus cooled.

The recess is preferably designed deep enough so that the cathode can be completely contained in it. In other words, the cathode does not protrude out of the recess over the top side, in particular, not in the area of the combustion zone.

According to a further embodiment, it is provided that the cathode extends from the recess to a further bottom side of the burner plate opposite the top side. This makes possible a simple way to conduct off the heat from the cathode to the opposite further bottom side which is cool.

According to a further embodiment, it is possible that the cathode is contained in a recess which opens towards the bottom side of the volume burner body. Besides this, it is also conceivable that to some extent the cathode is partially contained in a [lacuna] on the top side of the burner plate as well as in a [lacuna] on the bottom side of the volume burner body.

According to a further embodiment, it is provided that the recess is formed corresponding to the shape of the cathode. This provides a simple and inexpensive way to prevent undesired strong heating up of the cathode.

The cathode can be formed from a perforated plate or, preferably a spiral or meandering-shaped, bent wire. It is usefully made of a temperature-resistant metal.

The suggested burner arrangement is usefully used with gas burners in particular.

Examples will now be used to describe the invention in more detail based on the drawings. The figures are listed below:

FIG. 1 A perspective view of a first burner arrangement,

FIG. 2 A sectional view as per FIG. 1,

FIG. 3 A perspective view of a second burner arrangement,

FIG. 4 A detail view of area A in FIG. 3,

FIG. 5 A perspective view of a first cathode,

FIG. 6 A perspective view of a second cathode,

FIG. 7 A perspective view of a third cathode and

FIG. 8 A perspective view of a fourth cathode.

FIG. 1 and 2 show views of a first burner arrangement. The burner is a surface burner. A burner plate 1 made of a ceramic material, for example Al₂O₃, ZrO₂ or similar, has the form of a cylindrical disk. Burner plate 1 is provided with a plurality of axially running breakthroughs 2 to conduct a gaseous fuel, for example. Reference designator 3 denotes flames extending from a top side 4 of the burner plate 1. A diameter of the breakthroughs 2 is selected in such a manner that the spread of the flames 3, in other words the formation of a flame 3 within the breakthroughs 2, is impossible. A cathode 5 made of a temperature-resistant metal is contained in a correspondingly formed recess 6 which opens towards the top side 4. The depth of the recess 6 is such that the recess can completely hold the cathode 5 which is designed, for example, in the shape of a bent wire. In other words, the cathode 5 does not protrude over the top side 4. The breakthroughs 2 can extend into the recess 6. The recess 6 can be made either by milling, grinding or similar after the firing of the ceramic which forms the burner plate 1. But preferably the recess 6 will already be made before the firing of the burner plate 1 by appropriate shaping or processing of the green body.

Reference designator 7 denotes an anode which protrudes into the area of the flames 3 in the approximate opposite arrangement to cathode 5.

As FIG. 1 particularly shows, the ends 5a of the cathode 5 are led through and out of the burner plate 1 via a bottom side of burner plate 8.

FIG. 3 and 4 show a second burner arrangement. In this connection, a volume burner element 9 made in the shape of a cylindrical disk is provided above the top side 4 of the burner plate 1. A slit 11 formed between the top side 4 and a volume burner bottom side 10 has a width in the range of 1 to 5 mm.

The volume burner element 9 is usefully made of a porous material, for example a porous ceramic, a ceramic foam, metal braiding or similar. The volume burner element 9 has a further breakthrough 12 through which the anode 7 is led up to the vicinity of the top side 4 of the burner plate 1.

The function of the burner arrangements is stated below:

Gas flows through the breakthroughs 2 in the burner plate 1. The gas is ignited with a ignition device (not shown here). Because of this, the flames 3 extend from the top side 4 to the burner plate 1. Due to the formation of the flames 3, a significant change in the electrical conductivity is measured between the cathode 5 and the anode 7 via a measuring device (not shown here). This change shows the existence of the flames 3. If the flames 3 do not occur, due to a faulty ignition or gust of wind for example, or are extinguished, this is detected by the lack of increased conductivity between cathode 5 and anode 7. For example, a safety shutoff valve installed in a gas feeder line can be automatically closed.

To obtain as reliable conductivity measured values as possible, it has proven useful to maintain the cathode 5 within a specified temperature range. For this purpose, the cathode 5 is placed in the recess 6 which opens towards the top side 4 of the burner plate 1. As particularly shown in FIGS. 1 and 2, the flames 3 extend first from the top side 4 of the burner plate 1. In other words, the cathode 5 is not located within the flames 3. Apart from this, the cathode 5 can be surrounded with gas through the breakthroughs 2 extending into the recess 6 and thus be cooled or maintained within a specified temperature range. For further thermal stabilization of the cathode 5, it is useful to lead out its ends 5a through the bottom side of the burner plate 8. With this, heat transferred to the cathode 5 in the area of the top side 4 can be guided to a cooler area on the bottom side of the burner plate 8. The suggested arrangement of cathode 5 makes possible safe and reliable detection of the existence or non-existence of a flame 3.

FIG. 5 to 8 show possible embodiments of the cathode 5. In FIG. 5 to 7 the cathode 5 is made from a bent wire. It has at least one end 5a each for leading through up to the bottom side of the burner plate 8. As FIG. 5 to 7 show, the wire can be bent either meandering-shaped or also like a spiral.

The cathode 5 shown in FIG. 8 consists of a perforated plate with a heat dissipating and connection element 13 extending therefrom.

REFERENCE DESIGNATION LIST

1 Burner plate

2 Breakthrough

3 Flame

4 Top side

5 Cathode

5a End of the cathode

6 Recess

7 Anode

8 Bottom side of burner plate

9 Volume burner element

10 Bottom side of volume burner element

11 Slit

12 Further breakthrough

13 Heat dissipating and connection element

Claims

1. Burner arrangement with a burner plate (1) having a plurality of breakthroughs (2) and a monitoring unit to monitor the formation of a combustion zone (3) extending from the burner plate (1),

wherein the monitoring unit comprises a cathode (5) on a top side (4) of the burner plate (1) pointing towards the combustion zone (3) and an anode (7) extending into the area of the combustion zone,

characterized in that

the burner plate (1) is made of a non-metallic material and the cathode (5) is located as a separately formed component in the area of the top side (4) of the burner plate (1).

2. Burner arrangement as defined in claim 1, wherein a volume burner body (9) with a combustion-enabling, communicating porous space is located opposite the top side (4).

3. Burner arrangement as defined in claim 1, wherein a slit (11) of a specified width is provided between the top side (4) and a bottom side (10) of the volume burner body (9).

4. Burner arrangement as defined in claim 1, wherein the volume burner body (9) and/or the burner plate (1) is/are made of a ceramic material.

5. Burner arrangement as defined in claim 1, wherein the cathode (5) is located in the slit (11).

6. Burner arrangement as defined in claim 1, wherein the cathode (5) is contained in a recess (6) opening towards the top side (4) of the burner plate (1).

7. Burner arrangement as defined in claim 1, wherein at least some of the breakthroughs (2) provided in the burner plate (1) open in the recess (6).

8. Burner arrangement as defined in claim 1, wherein the cathode (5) extends from the recess (6) into a further bottom side (8) of the burner plate (1) opposite the top side (4).

9. Burner arrangement as defined in claim 1, wherein the cathode (5) is contained in a recess (6) which opens towards the bottom side (10) of the volume burner body (9).

10. Burner arrangement as defined in claim 1, wherein the recess (6) is formed corresponding to the form of the cathode (5).

11. Burner arrangement as defined in claim 1, wherein the cathode (5) is formed from a perforated plate or preferably a spiral or meandering-shaped wire.

12. Burner arrangement as defined in claim 1, wherein the burner arrangement is part of a gas burner.