Patent Description:
From the state of the art, an air-gas mixture burning appliance with an air-gas mixing unit, a burning unit, and a gas supply unit is known. In this air-gas mixture burning appliance, hydrogen may be used as gas and mixed with air to form a combustible air-gas mixture.

More specifically, such an air-gas mixture burning appliance usually mixes air and gas directly before the burning unit. During the ignition phase, the combustible air-gas mixture enters the burning unit where it is ignited at a low heat input to assist with stability and acoustics upon start up. However, sometimes the combustible air-gas mixture is not ignited immediately, which can lead to a build-up of the combustible air-gas mixture in the burning unit. A delayed ignition, which refers to igniting the built-up combustible air-gas mixture, usually leads to an explosion that may damage internal components of the air-gas mixture burning appliance and endanger the surrounding environment.

Delayed ignition is unproblematic for current natural gas burning appliances. However, delayed ignition may have severe consequences for appliances that burn a combustible air-hydrogen mixture.

For example, the explosion caused by a delayed ignition of a combustible air-hydrogen mixture may not only damage internal components of the appliance, but damaged internal components may be ejected from the boiler case of the appliance. Moreover, the high sound levels that such an explosion produces, could potentially lead to hearing damage of people who are in the vicinity of such an appliance.

Document <CIT> describes a combustion chamber system for use in a gas turbine system, with a peripheral wall which runs around a longitudinal axis and which delimits a combustion chamber in which a reaction zone is formed during operation. with a burner head arranged on the input side of the combustion chamber for adding fuel and oxidizer into the combustion chamber, which comprises at least one fuel supply for adding fuel to the oxidizer and with a combustion chamber outlet on the output side of the combustion chamber. A defined positioning of the combustion chamber system even during operation is achieved in that the combustion chamber system is subdivided into at least a first and a second structural unit, which in the installed state are arranged axially one behind the other in a technical application second assembly extends at least in regions downstream of the first assembly, that the assemblies are axially displaceable relative to one another, that the first assembly comprises a first section of the peripheral wall, and / or that the second structural unit comprises a second partial section of the peripheral wall and that the division of the combustion chamber system into the structural units adjoins one or between two partial sections is arranged.

Document <CIT> describes a gas burner with a plurality of concentric circular flame crowns, with a burner body apt to be mounted on the surface of a cooking plate, a burner body apt to be mounted on the surface of a cooking plate and provided with a first chamber for the diffusion of the air/gas mixture, and whose top is closed by a first cover, a second outer annular burner surrounding said central burner, a first gas inlet in communication with said body, a first gas injector able of injecting a gas flow into a respective Venturi pipe to said first central burner, a second gas inlet in communication with said body, wherein said second annular burner is provided with two separate diffusion chambers, and whose top is closed by a second cover, wherein said second gas inlet is in communication with said two separate chambers which are not in communication to each other, two distinct injectors connected with said second gas inlet and placed on the same end position of said second gas inlet, two respective horizontally oriented Venturi pipes, each of which being able of supplying with an air/gas mixture a respective of said two diffusion chambers; said first gas injector and the respective Venturi pipe for the central burner are horizontally oriented, and preferably they are positioned between the two Venturi pipes dedicated to said two diffusion chambers.

In the remainder of this description, the term "gas" refers as any fuel in gaseous form that, when mixed with air, forms a combustible air-gas mixture. Examples for such a gas include hydrogen, propane, butane, methane, liquefied petroleum gas, etc..

The present invention relates to an air-gas mixture burning appliance that comprises a burning unit for burning a combustible air-gas mixture, an air-gas mixing unit that is arranged upstream of the burning unit and comprises a predetermined plurality of air-gas mixers for mixing of air and gas to form the combustible air-gas mixture, and a gas supply unit that is arranged upstream of the air-gas mixing unit, the gas supply unit comprising: a first gas flow channel, a plurality of second gas flow channels that is arranged between the first gas flow channel and the predetermined plurality of air-gas mixers, and a gas flow distance regulating device that is arranged between the first gas flow channel and the plurality of second gas flow channels, the gas flow distance regulating device being adapted to regulating a flow distance of the gas from the first gas flow channel to the plurality of second gas flow channels in order to adjust an arrival time of the gas at the predetermined plurality of air-gas mixers and comprising a baffle plate that extends in longitudinal direction from a center towards two ends and that is adapted to route the gas from the first gas flow channel to at least one of the plurality of second gas flow channels.

Advantageously, the inventive air-gas mixture burning appliance may uniformly supply gas at all air-gas mixers during the ignition phase of the air-gas mixture burning appliance. Thus, the arrival time of the combustible air-gas in the burning units may be synchronized, which may prevent an initial failure to ignite the combustible air-gas mixture in the burning unit. Preventing the initial failure to ignite also prevents the build-up of a damaging concentration of the combustible air-gas mixture in the burning unit, and thereby eliminates the risks associated with a delayed ignition of such a damaging amount of the combustible air-gas mixture. More specifically, synchronizing the arrival time of the gas at the air-gas mixers before the ignition of the combustible air-gas mixture may prevent an explosion and the associated damage in the event of a delayed ignition. Moreover, adjusting the arrival time of the gas at all air-gas mixers may enable the use of gases that have a lower density than air. In fact, the volumetric flow rate of gas through a fixed geometric restriction for a given driving pressure difference is inversely related to the gas density. Thus, adjusting the arrival time of the gas at the air-gas mixers will subsequently prevent that some gas flow channels remain filled with air while other gas flow channels take a preferential share of the total flow of gas and thereby prevent the accumulation of the combustible air-gas mixture in the burning unit even for gases with a lower density than air. Moreover, the flow distance of the gas from the first gas flow channel to at least one of the plurality of second gas flow channels may be prolonged.

According to one aspect, regulating the flow distance of the gas further comprises adjusting flow distances from the first gas flow channel to each one of the plurality of second gas flow channels to provide for a substantially simultaneous arrival time of the gas at the predetermined plurality of air-gas mixers.

Thus, the flow distance of the gas from the first gas flow channel to each one of the predetermined number of air-gas mixers may be synchronized.

According to one aspect, the first gas flow channel is mounted to the gas flow distance regulating device at a gas flow distance regulating device inlet, wherein the gas flows through the gas flow distance regulating device inlet in a predetermined gas flow direction, and wherein the baffle plate is arranged perpendicular to the predetermined gas flow direction.

Thus, the gas may be easily and efficiently routed from the first gas flow channel to the plurality of second gas flow channels.

Accordingly, the gas flow from the first gas flow channel to the plurality of second gas flow channels may be fine-tuned.

According to one aspect, the baffle plate comprises a first plurality of perforations that is arranged between first and second distances from the center and a second plurality of perforations that is arranged between third and fourth distances from the center, wherein each perforation of the first and second plurality of perforations has a cross-sectional area, wherein a sum of the cross-sectional areas of all perforations of the first plurality of perforations is smaller than a sum of the cross-sectional areas of all perforations of the second plurality of perforations, and wherein the greater one of the first and second distances is smaller than or equal to the smaller one of the third and fourth distances.

Thus, the gas flow from the first gas flow channel to the gas flow channels of the plurality of second gas flow channels that are further away from the center of the baffle plate is less restricted than the gas flow from the first gas flow channel to the gas flow channels of the plurality of second gas flow channels that are closer to the center of the baffle plate.

According to one aspect, the first plurality of perforations is greater than the second plurality of perforations.

Accordingly, the first plurality of perforations may include a comparatively large number of small perforations and the second plurality of perforations a comparatively smaller number of larger perforations.

According to one aspect, the first plurality of perforations is smaller than or equal to the second plurality of perforations.

Accordingly, the first plurality of perforations may include a comparatively small number of perforations of approximately the same size or smaller than the second plurality of perforations.

According to one aspect, the gas flow distance regulating device further comprises at least one additional baffle plate that is arranged parallel to the baffle plate.

Thus, the gas flow distance regulating device may provide for a staggered arrangement of a plurality of baffle plates that may be adapted to fine-tune the flow distance between the first gas flow channel and the individual channels of the plurality of second gas flow channels.

Preferably, the gas has a density that is smaller than half the density of the air.

Thus, the air-gas mixture burning appliance may be adapted to burn a combustible air-gas mixture with a gas that has less than half the density of air.

Accordingly, the air-gas mixture burning appliance may burn a combustible air-hydrogen mixture.

Exemplary embodiments of the present invention are described in detail hereinafter with reference to the attached drawings. In these attached drawings, identical or identically functioning components and elements are labelled with identical reference signs and they are generally only described once in the following description.

<FIG> shows an exemplary air-gas mixture burning appliance <NUM> with an air-gas mixing unit <NUM>, a burning unit <NUM>, and a flame detector <NUM>. By way of example, the air-gas mixture burning appliance <NUM> may be used in a boiler or, more generally, in a building heating system. Preferably, the gas used is hydrogen such that the air-gas mixture burning appliance <NUM> forms an air-hydrogen mixture burning appliance.

The air-gas mixing unit <NUM> is preferably adapted for mixing of air and gas to form a combustible air-gas mixture <NUM>. Preferentially, the combustible air-gas mixture <NUM> is a homogenous mixture of the air and the gas.

By way of example, the air-gas mixing unit <NUM> includes an air supply unit <NUM> and a gas supply unit <NUM>. Illustratively, the air supply unit <NUM> includes a fan <NUM> that may be operated with an adaptable fan speed and/or within predetermined ranges of fan speeds to draw air into the air-gas mixing unit <NUM>.

The air supply unit <NUM> and the gas supply unit <NUM> may be interconnected via a predetermined number of air-gas mixers <NUM> which forms a corresponding predetermined number of discrete points of mixing <NUM>. Preferably, the combustible air-gas mixture <NUM> is formed at the predetermined number of discrete points of mixing <NUM> and guided via the predetermined number of air-gas mixers <NUM> to the burning unit <NUM>.

By way of example, at least a first and a second air-gas mixer <NUM> of the predetermined number of air-gas mixers <NUM> may be identical. For example, all air-gas mixers <NUM> of the predetermined number of air-gas mixers <NUM> may be identical. If desired, at least a first and a second air-gas mixer <NUM> of the predetermined number of air-gas mixers <NUM> may be different. By way of example, at least one of the predetermined number of air-gas mixers <NUM> may be a venturi air-gas mixer.

Illustratively, the burning unit <NUM> is provided with a burner surface <NUM> that is arranged downstream of the air-gas mixing unit <NUM> such that the combustible air-gas mixture <NUM> that is formed at the predetermined number of discrete points of mixing <NUM> flows towards the burner surface <NUM>. The combustible air-gas mixture <NUM> is burned by the burning unit <NUM> and, more specifically, at the burner surface <NUM>.

By way of example, the burner surface <NUM> is illustrated with a comparatively small flame <NUM> which occurs e.g. during an ignition phase of the air-gas mixture burning appliance <NUM>. As an example, during such an ignition phase, the air-gas mixing unit <NUM> may have a low firing rate, i.e. a comparatively low rate at which feed of the combustible air-gas mixture <NUM> from the air-gas mixing unit <NUM> to the burning unit <NUM> occurs, in terms of volume, heat units, or weight per unit time. As another example, during such an ignition phase, the gas supply unit <NUM> may regulate a relative flow distance of the gas in order to adjust an arrival time of the gas at the different air-gas mixers <NUM> of the predetermined number of air-gas mixers <NUM> such that a uniform small flame <NUM> may occur simultaneously upon ignition at the entire burner surface <NUM>.

According to one aspect, the flame detector <NUM> is provided for sensing presence of a flame <NUM> in the burning unit <NUM>. By way of example, the flame detector <NUM> detects a flame signal <NUM> in the burning unit <NUM>. Thus, the flame detector <NUM> is suitable for determining whether a flame <NUM> is present in the burning unit <NUM>, or not. However, it should be noted that suitable flame detection techniques that may be used with the flame detector <NUM> are well-known to the person skilled in the art and are, therefore, not described in more detail, for brevity and conciseness. For instance, the flame detector <NUM> may use any suitable sensing element for sensing presence of the flame <NUM> in the burning unit <NUM>.

Illustratively, the flame detector <NUM> is connected to a controller <NUM>. Preferably, the controller <NUM> is adapted to control supply of gas to the air-gas mixing unit <NUM>, in particular to control the gas supply unit <NUM>, on the basis of a detection signal <NUM> provided by the flame detector <NUM>.

The detection signal <NUM> may be created and/or provided by the flame detector <NUM>, or alternatively by the controller <NUM>, by comparing the detected flame signal <NUM> with a predetermined flame detection threshold. Thus, the controller <NUM> may create a control signal <NUM> on the basis of the detection signal <NUM>.

<FIG> shows an illustrative gas supply unit <NUM> of an air-gas mixture burning appliance (e.g., air-gas mixture burning appliance <NUM> of <FIG>). If desired, gas supply unit <NUM> may be arranged upstream of an air-gas mixing unit (e.g., air-gas mixing unit <NUM> of <FIG>).

The air-gas mixing unit may be arranged upstream of a burning unit (e.g., burning unit <NUM> of <FIG>) for burning a combustible air-gas mixture <NUM>. Illustratively, the air-gas mixing unit may include a predetermined number of air-gas mixers <NUM> for mixing of air <NUM> and gas <NUM> to form the combustible air-gas mixture <NUM>. The air <NUM> may be mixed with the gas <NUM> at discrete points of mixing <NUM> in the air-gas mixers <NUM>.

Illustratively, the gas <NUM> may have a density that is smaller than <NUM>% the density of the air <NUM>. If desired, the gas <NUM> may have a density that is smaller than half the density of the air <NUM>. As an example, the gas <NUM> may be hydrogen.

Illustratively, gas supply unit <NUM> may be adapted to regulating the flow of gas <NUM> to the air-gas mixers <NUM>. If desired, the gas supply unit <NUM> may include a first gas flow channel <NUM> and a plurality of second gas flow channels <NUM>. The plurality of second gas flow channels <NUM> may be arranged between the first gas flow channel <NUM> and the predetermined number of air-gas mixers <NUM>. Illustratively, gas supply unit <NUM> may include a gas flow distance regulating device <NUM>. The gas flow distance regulating device <NUM> may be arranged between the first gas flow channel <NUM> and the plurality of second gas flow channels <NUM>.

Illustratively, the gas flow distance regulating device <NUM> may be adapted to regulating a relative flow distance of the gas <NUM> from the first gas flow channel <NUM> to the plurality of second gas flow channels <NUM>. For example, the gas flow distance regulating device <NUM> may regulate the relative flow distance of the gas <NUM> from the first gas flow channel <NUM> to the plurality of second gas flow channels <NUM> in order to adjust an arrival time of the gas 117a, 117b, 117c, 117d, 117e, 117f at the predetermined number of air-gas mixers <NUM>.

By way of example, the gas flow distance regulating device <NUM> may adjust flow distances from the first gas flow channel <NUM> to each one of the plurality of second gas flow channels <NUM> to provide for a substantially simultaneous arrival time of the gas 117a, 117b, 117c, 117d, 117e, 117f at the predetermined number of air-gas mixers <NUM>.

If desired, the gas flow distance regulating device <NUM> may be adapted to regulating the relative flow distance of the gas <NUM> from the first gas flow channel <NUM> to the plurality of second gas flow channels <NUM> such that the same concentration of the gas 117a, 117b, 117c, 117d, 117e, 117d arrives at the predetermined number of air-gas mixers <NUM>, preferably at the same time.

Illustratively, the gas flow distance regulating device <NUM> may include a baffle plate <NUM>. The baffle plate <NUM> may be adapted to route the gas <NUM> from the first gas flow channel <NUM> to at least one of the plurality of second gas flow channels <NUM>.

If desired, the baffle plate <NUM> may be adapted to route the gas <NUM> from the first gas flow channel <NUM> to more than one of the plurality of second gas flow channels <NUM>. For example, the baffle plate <NUM> may be adapted to route the gas <NUM> from the first gas flow channel <NUM> to all gas flow channels of the plurality of second gas flow channels <NUM>.

As shown in <FIG>, the first gas flow channel <NUM> may be mounted to the gas flow distance regulating device <NUM> at a gas flow distance regulating device inlet <NUM>. The gas <NUM> may flow through the gas flow distance regulating device inlet <NUM> in a predetermined gas flow direction <NUM>. For example, the predetermined gas flow direction <NUM> may be parallel to a z-axis.

The baffle plate <NUM> may have a length extension parallel to an x-axis, a height extension parallel to a y-axis, and a thickness parallel to the z-axis. As shown in <FIG>, the x-axis, the y-axis, and the z-axis may form a Cartesian coordinate system, and the baffle plate <NUM> may have a uniform thickness.

If desired, the baffle plate <NUM> may be arranged relative to the predetermined gas flow direction <NUM> at an angle that is between <NUM>° and <NUM>°. Illustratively, the baffle plate <NUM> may be arranged perpendicular to the predetermined gas flow direction <NUM>. In other words, the length and height extensions of the baffle plate <NUM> may form a plane that is parallel to the x-y-plane.

Illustratively, the gas flow distance regulating device <NUM> may include a plurality of baffle plates <NUM> that are arranged at predetermined angles relative to each other and to the predetermined gas flow direction.

<FIG> shows a schematic view of the gas supply unit <NUM> of <FIG> with gas flow distance regulating device <NUM>. The gas flow distance regulating device <NUM> may regulate the relative flow distance of gas <NUM> from the first gas flow channel <NUM> to the plurality of second gas flow channels <NUM>. For example, the gas flow distance regulating device <NUM> may regulate the relative flow distance of the gas <NUM> from the first gas flow channel <NUM> to the plurality of second gas flow channels <NUM> to provide for a substantially simultaneous arrival time of the gas 117a, 117b, 117c, 117d, 117e, 117fat the predetermined number of air-gas mixers <NUM>.

As shown in <FIG>, the gas flow distance regulating device <NUM> may include a baffle plate <NUM>. The baffle plate <NUM> may regulate the relative flow distance of the gas <NUM>.

As an example, consider the scenario in which the gas supply unit <NUM> is filled with air before the initial supply of gas <NUM> that enter the gas flow distance regulating device <NUM> at the gas flow distance regulating device inlet <NUM> in a direction that is substantially parallel to a z-axis. Consider further that the gas flow distance regulating device <NUM> includes baffle plate <NUM> that is arranged parallel to the x-y-plane of the Cartesian coordinate system as shown in <FIG>, such that the gas <NUM> has to flow around the baffle plate <NUM>, and that the baffle plate <NUM> completely shuts off the direct path from the gas flow distance device inlet <NUM> to the gas flow channels <NUM> that route gas flows 117c and 117d.

In this scenario, the gas flows 117a, 117c, 117d, and 117f flow substantially the same distance from the gas flow distance device inlet <NUM> to the respective gas flow channels <NUM> of the plurality of second gas flow channels <NUM>, while the gas flows 117b and 117e flow comparatively over a smaller distance from the gas flow distance device inlet <NUM> to the respective gas flow channels <NUM>.

Thus, the baffle plate <NUM> may regulate the relative flow distance of the gas <NUM> from the first gas flow channel <NUM> to each one of the plurality of second gas flow channels <NUM>. Thereby, the gas flow distance regulating device <NUM> provides for a substantially simultaneous arrival time of the gas 117a, 117b, 117c, 117d, 117e, 117fat the predetermined number of air-gas mixers <NUM>.

As a result, the air-gas mixers <NUM> that mix air <NUM> with the gas 117a, 117b, 117c, 117d, 117e, 117fto form the combustible air-gas mixture <NUM> may provide a uniform distribution of the combustible air-gas mixture <NUM> at a burning unit (e.g., burning unit <NUM> of <FIG>) that may be arranged downstream of the air-gas mixers <NUM>. Thereby, a failure to ignite the combustible air-gas mixture <NUM> combined with an accumulation of substantial quantities of the combustible air-gas mixture <NUM> in the burning unit (e.g., in a combustion chamber) may be prevented and the associated damages caused by a delayed ignition may be avoided.

<FIG> shows a schematic view of an illustrative baffle plate <NUM>. The baffle plate <NUM> may have a length extension parallel to an x-axis, a height extension parallel to a y-axis, and a thickness parallel to a z-axis. The x-, y-, and z-axes may form a Cartesian coordinate system.

Illustratively, the baffle plate <NUM> may have a uniform thickness. In other words, the thickness may be the same along the entire length and height extensions of the baffle plate <NUM>.

If desired, the thickness of the baffle plate <NUM> may be non-uniform. For example, the baffle plate <NUM> may have the greatest thickness at the center <NUM> of the baffle plate <NUM>. The thickness may decrease towards the ends <NUM>, <NUM> of the of the baffle plate <NUM>, e.g. to provide for a more streamlined baffle plate <NUM>.

Consider the scenario in which the baffle plate <NUM> has a uniform thickness. In this scenario, the baffle plate <NUM> may be straight such that the length and height extensions of the baffle plate <NUM> form a plane such that every point on the surface of the baffle plate <NUM> has the same coordinate on the z-axis (e.g., such as the baffle plate <NUM> shown in <FIG> and <FIG>).

Alternatively, the baffle plate <NUM> may have a different shape such that at least two points on the surface of the baffle plate <NUM> that are at different height and/or different length extensions have a different coordinate on the z-axis. As an example, the baffle plate <NUM> may be curved.

A straight baffle plate <NUM> may cause turbulences to the gas flow in gas flow distance regulating device <NUM>. In some scenarios, turbulences in the gas flow may affect the arrival time of the gas flows (e.g., gas flow 117a compared to gas flow 117c of <FIG>) at the respective air-gas mixers, even though the distances from the gas flow distance regulating device inlet to the respective air-gas mixers are the same.

If desired, the baffle plate <NUM> may include perforations <NUM>. <FIG> shows a schematic view of an illustrative baffle plate <NUM> with perforations <NUM>. The perforations <NUM> may mitigate at least a portion of the negative effect of turbulences on the arrival time of the different gas flows at the air-gas mixers.

Illustratively, the baffle plate <NUM> may include perforations <NUM> that have a uniform cross-sectional area. If desired, at least two perforations <NUM> may have a different cross-sectional area.

The perforations <NUM> may have any cross-sectional shape. For example, the perforations <NUM> may be round, oval, elliptical, triangular, rectangular, etc. Preferably, the perforations <NUM> are round.

By way of example, the perforations <NUM> may be distributed uniformly across the baffle plate <NUM>. As shown in <FIG>, the perforations <NUM> may be distributed non-uniformly across the baffle plate <NUM>. If desired, the perforations <NUM> may be distributed uniformly in some sections of the baffle plate <NUM>.

<FIG> show schematic views of illustrative baffle plates <NUM> with perforations <NUM> that are distributed uniformly in some sections of the respective baffle plate <NUM>.

For example, an illustrative baffle plate <NUM> may include a first plurality of perforations <NUM> that is arranged between first and second distances <NUM>, <NUM> from the center <NUM> of the baffle plate <NUM> and a second plurality of perforations <NUM> that is arranged between third and fourth distances <NUM>, <NUM> from the center <NUM> of the baffle plate.

Illustratively, each perforation <NUM> of the first and second plurality of perforations <NUM>, <NUM> may have a cross-sectional area (i.e., an area in the x-y plane). A sum of the cross-sectional areas of all perforations <NUM> of the first plurality of perforations <NUM> may be smaller than a sum of the cross-sectional areas of all perforations <NUM> of the second plurality of perforations <NUM>, and the greater one of the first and second distances <NUM>, <NUM> may be smaller than or equal to the smaller one of the third and fourth distances <NUM>, <NUM>. <FIG> show such illustrative baffle plates <NUM>.

<FIG> shows a schematic view of a baffle plate <NUM> with perforations <NUM> that are distributed uniformly in some sections of the baffle plate <NUM>. As shown in <FIG>, at least two perforations <NUM> may have a different cross-sectional area.

Illustratively, baffle plate <NUM> may have a first plurality of perforations <NUM> with a first cross-sectional area, which is the sum of all perforations <NUM> of the first plurality of perforations <NUM>, in the center <NUM> of the baffle plate <NUM> and a second plurality of perforations <NUM> with a second cross-sectional area, which is the sum of all perforations <NUM> of the second plurality of perforations <NUM> towards the end <NUM> in length direction of the baffle plate <NUM>.

As shown in <FIG>, the second cross-sectional area of the second plurality of perforations <NUM> may be comparatively larger than the first cross-sectional area of the first plurality of perforations <NUM>. Nevertheless, the first plurality of perforations <NUM> has nine perforations and is therefore greater in number than the second plurality of perforations <NUM>, which has four perforations.

The first plurality of perforations <NUM> may be arranged between first and second distances <NUM>, <NUM> from the center <NUM> of the baffle plate <NUM>, and the second plurality of perforations <NUM> may be arranged between third and fourth distances <NUM>, <NUM> from the center <NUM> of the baffle plate. Illustratively, the greater of the first and second distances <NUM>, <NUM> may be smaller than the smaller one of the third and fourth distances <NUM>, <NUM>. If desired, the baffle plate <NUM> may be arranged in the gas flow distance regulating device <NUM> such that the first plurality of perforations <NUM> is closer to the center of the gas flow distance regulating device inlet (e.g., gas flow distance regulating device inlet <NUM> of <FIG> or <FIG>) than the second plurality of perforations <NUM>.

Baffle plate <NUM> of <FIG> is shown with perforations that increase in cross-sectional area from the center <NUM> of the baffle plate <NUM> towards the ends <NUM>, <NUM> of the baffle plate <NUM>. However, some sections may have fewer perforations <NUM> that each have comparatively greater cross-sectional areas than the neighboring section that is closer to the center <NUM> of the baffle plate <NUM>, while other sections may have more perforations <NUM> that each have comparatively smaller cross-sectional areas than the neighboring section that is closer to the center <NUM> of the baffle plate <NUM>.

<FIG> shows a schematic view of a baffle plate <NUM> with perforations <NUM> that are distributed uniformly in some sections of the baffle plate <NUM>. As shown in <FIG>, all perforations <NUM> may have substantially the same cross-sectional area. If desired, some perforations <NUM> may have a different cross-sectional area.

Illustratively, baffle plate <NUM> may have a first plurality of perforations <NUM> with a first cross-sectional area, which is the sum of all perforations <NUM> of the first plurality of perforations <NUM>, in the center of the baffle plate <NUM> and a second plurality of perforations <NUM> with a second cross-sectional area, which is the sum of all perforations <NUM> of the second plurality of perforations <NUM> towards the end <NUM>, <NUM> of the baffle plate <NUM>.

As shown in <FIG>, the second cross-sectional area of the second plurality of perforations <NUM> may be comparatively larger than the first cross-sectional area of the first plurality of perforations <NUM>. Illustratively, the first plurality of perforations <NUM> has three perforations and is therefore smaller than the second plurality of perforations <NUM>, which has <NUM> perforations.

The first plurality of perforations <NUM> may be arranged between first and second distances <NUM>, <NUM> from the center <NUM> of the baffle plate <NUM>, and the second plurality of perforations <NUM> may be arranged between third and fourth distances <NUM>, <NUM> from the center <NUM> of the baffle plate <NUM>. Illustratively, the greater of the first and second distances <NUM>, <NUM> may be smaller than the smaller one of the third and fourth distances <NUM>, <NUM>. If desired, the baffle plate <NUM> may be arranged in the gas flow distance regulating device <NUM> such that the first plurality of perforations <NUM> is closer to the center of the gas flow distance regulating device inlet than the second plurality of perforations <NUM>.

The gas flow distance regulating device <NUM> of <FIG> or <FIG> is shown to include a single baffle plate <NUM>. However, the gas flow distance regulating device <NUM> may include more than one baffle plate, if desired. For example, the gas flow distance regulating device <NUM> may include three or more baffle plates, for example to fine tune the arrival time of the gas 117a, 117b, 117c, 117d, 117e, 117f at the different air-gas mixers <NUM>.

<FIG> shows a schematic view of a gas supply unit <NUM> with a gas flow distance regulating device <NUM> that comprises more than one baffle plate <NUM>. The baffle plates <NUM> may be adapted to route the gas <NUM> from the first gas flow channel <NUM> to at least one of the plurality of second gas flow channels <NUM>. If desired, the baffle plates <NUM> may be adapted to route the gas <NUM> from the first gas flow channel <NUM> to each one of the plurality of second gas flow channels <NUM> to provide for a substantially simultaneous arrival time of the gas 117a, 117b, 117c, 117d, 117e, 117f at the predetermined number of air-gas mixers <NUM>.

Illustratively, the first gas flow channel <NUM> is mounted to the gas flow distance regulating device <NUM> at a gas flow distance regulating device inlet <NUM>. The gas <NUM> flows through the gas flow distance regulating device inlet <NUM> in a predetermined gas flow direction that may be parallel to the z-axis.

As shown in <FIG>, the gas flow distance regulating device <NUM> may include seven baffle plates <NUM>. Preferably, the baffle plate <NUM> that is closest to the gas flow distance regulating device inlet <NUM> may be arranged perpendicular to the predetermined gas flow direction (i.e., parallel to the x-y-axis plane).

Illustratively, all baffle plates <NUM> may be arranged parallel to each other and to the x-y-axis plane. If desired, at least two baffle plates <NUM> may be arranged non-parallel to each other and/or non-parallel to the x-y-axis plane. For example, at least two baffle plates <NUM> may be arranged relative to each other at an angle that is between <NUM> degrees and <NUM> degrees.

As shown in <FIG>, the number of aligned baffle plates <NUM> may double in direction of the z-axis. For example, alignment <NUM> that is closest to the gas flow distance regulating device inlet <NUM> may include a single baffle plate <NUM>. Alignment <NUM> that is in direction of the z-axis further away from the gas flow distance regulating device inlet <NUM> may include two aligned baffle plates <NUM>. The two aligned baffle plates <NUM> of alignment <NUM> may be arranged parallel to the single baffle plate <NUM> of alignment <NUM>. Alignment <NUM> that is even further away from the gas flow distance regulating device inlet <NUM> in direction of the z-axis may include four aligned baffle plates <NUM>.

Thus, as shown in <FIG>, gas flow distance regulating device <NUM> may include three parallel alignments <NUM>, <NUM>, <NUM> of baffle plates <NUM>. If desired, gas flow distance regulating device <NUM> may include more or less than three parallel alignments of baffle plates <NUM>. For example, gas flow distance regulating device <NUM> may include two, four, five, six, etc. parallel alignments of baffle plates <NUM>.

Illustratively, the number of aligned baffle plates <NUM> at each alignment <NUM>, <NUM>, <NUM> and/or the number of alignments and/or the arrangements of the individual baffle plates <NUM> may be selected based on the number of parallel gas flow channels in the plurality of second gas flow channels <NUM>.

By way of example, all baffle plates <NUM> in an alignment <NUM>, <NUM>, <NUM> may have the same dimensions. If desired, at least two baffle plates <NUM> in the same alignment <NUM>, <NUM>, <NUM> may have different dimensions.

As shown in <FIG>, two baffle plates <NUM> that are in different parallel alignments <NUM>, <NUM>, <NUM> may have different dimensions. If desired, at least two baffle plates <NUM> that are in different parallel alignments <NUM>, <NUM>, <NUM> may have the same dimensions.

If desired, at least one baffle plate <NUM> may include at least one perforation (e.g., one of perforations <NUM> of <FIG>, <FIG>). In some embodiments, all baffle plates <NUM> may include at least one perforation.

Gas supply unit <NUM> of <FIG> and <FIG> is shown with a single first gas flow channel <NUM>. However, it should be noted that the first gas flow channel <NUM> of the gas supply unit <NUM> of <FIG> and <FIG> is only cited by way of example, and not for limiting the invention accordingly. Instead, gas supply units <NUM> with more than one first gas flow channel are likewise contemplated. For example, the gas supply unit <NUM> may have two or more gas flow channels that supply gas to the plurality of second gas flow channels <NUM>.

Claim 1:
An air-gas mixture burning appliance (<NUM>), comprising:
a burning unit (<NUM>) for burning a combustible air-gas mixture (<NUM>),
an air-gas mixing unit (<NUM>) that is arranged upstream of the burning unit (<NUM>) and comprises a predetermined plurality of air-gas mixers (<NUM>) for mixing of air (<NUM>) and gas (<NUM>) to form the combustible air-gas mixture (<NUM>), and
a gas supply unit (<NUM>) that is arranged upstream of the air-gas mixing unit (<NUM>), the gas supply unit (<NUM>) comprising:
a first gas flow channel (<NUM>),
a plurality of second gas flow channels (<NUM>) that is arranged between the first gas flow channel (<NUM>) and the predetermined plurality of air-gas mixers (<NUM>), and
a gas flow distance regulating device (<NUM>) that is arranged between the first gas flow channel (<NUM>) and the plurality of second gas flow channels (<NUM>), the gas flow distance regulating device (<NUM>) being adapted to regulating a flow distance of the gas (<NUM>) from the first gas flow channel (<NUM>) to the plurality of second gas flow channels (<NUM>) in order to adjust an arrival time of the gas (<NUM>) at the predetermined plurality of air-gas mixers (<NUM>) and comprising a baffle plate (<NUM>) that extends in longitudinal direction from a center (<NUM>) towards two ends (<NUM>, <NUM>) and that is adapted to route the gas (<NUM>) from the first gas flow channel (<NUM>) to at least one of the plurality of second gas flow channels (<NUM>).