Heating device, assembly of a flame arrestor and a burner and use of a seal

Abstract

A heating appliance (1) is proposed, comprising a burner (3) arranged on a burner door (15), including a perforated plate (17) between a burner cavity (25) and a combustion chamber (8) of the heating appliance, wherein the burner (3) includes a flame arrestor (18) arranged in the burner cavity (25), which is designed to form a sealing area (26) with the burner door (15). Advantageously, this prevents flame flashback, as bypass flows of the combustion mixture around the flame arrestor (18) are prevented. The sealing area (26) can be formed in a flow opening (19) of the burner door (15) or a groove (21) can be provided in the burner door (15) into which the flame arrestor (18) engages. Furthermore, an arrangement (16) of a burner (3) and a flame arrestor (18) and the use of a seal (20) are proposed.

Description

[0001] The invention relates to a heating device, an arrangement of a flame arrester and a burner and a use of a seal.

[0002] A large number of heating devices are known which burn a combustion mixture of a fuel, in particular gas or hydrogen, and ambient air in a combustion chamber in order to generate heat to supply a building or to provide hot water.

[0003] As part of efforts to avoid fossil fuels, hydrogen is becoming increasingly important as a fuel for heating appliances. Due to the properties of hydrogen, particularly its increased flame speed, the risk of flashbacks increases when using hydrogen as a fuel.

[0004] A flame flashback, also known as backfiring, is the propagation of a flame from a burner against the flow direction of the combustion mixture into a mixture channel of the heater. Due to the resulting pressure surge, a flame flashback can cause significant noise pollution and damage to the heater, particularly the delivery system.

[0005] For this purpose, EP 3 974 719 A1 proposes placing a flame arrester between an air supply and a perforated plate of the burner, which is impervious to flame penetration. This prevents further penetration of a flame into a mixture gas line of the heater. A similar design is also described in DE 693 22 622 T2. However, it has been shown that defects in the flame arrester, often in the transition area to a burner door, can occur, allowing the flame to enter the mixture channel and thus causing a flashback.

[0006] EP 3 751 196 A1 describes an alternative design of a flame arrester. This comprises a check valve arranged in the area of ​​the mixture channel, which closes when a higher pressure occurs downstream than upstream, thus preventing the spread of fire into the mixture channel. The disadvantage is that the valve's reaction time can allow a flame to pass through, and the valve is also maintenance-intensive due to its moving parts.

[0007] Based on this, the object of the invention is to propose a heater, an arrangement of a flame arrester and a burner, and a seal that at least partially overcomes the described problems of the prior art. In particular, flashbacks are to be robustly prevented.

[0008] In addition, the invention should at least not significantly increase the complexity of a heater, require only minor structural changes to a heater and enable easy integration into an existing production process.

[0009] These objects are achieved by the features of the independent patent claims. Further advantageous embodiments of the solution proposed here are specified in the independent patent claims. It is pointed out that the features listed in the dependent patent claims can be combined with one another in any technologically expedient manner and define further embodiments of the invention. Furthermore, the features specified in the patent claims are further specified and explained in the description, with further preferred embodiments of the invention being presented.

[0010] This is achieved by a heating device comprising a burner arranged on a burner door, which includes a flame arrester configured to form a sealing area with the burner door. The burner can be attached to the burner door by means of a burner seal. The flame arrester and burner door can thus form a sealing area independent of the burner seal, which can be located in the same sealing plane or, in particular, in a second sealing plane of the burner seal.

[0011] The heater is, in particular, a gas heater designed to burn a combustible gas, such as natural gas or, in particular, hydrogen, with the addition of ambient air and to generate thermal energy, for example, to heat a heat transfer medium in a heating circuit or to provide hot water. In particular, the heater can be a condensing boiler. The heater typically has a combustion chamber and a conveying device or fan that can convey a mixture of fuel and combustion air via a mixture duct into a combustion chamber in which a burner is arranged. The combustion products can then be fed to an exhaust system through an exhaust duct of the heater.

[0012] The burner can comprise at least one flat perforated plate or a cylindrical perforated plate arranged between a burner cavity and the combustion chamber. The burner cavity can be connected to the mixture channel in such a way that combustion mixture can flow from the mixture channel through the burner cavity, exit the perforated plate, and be burned there. An ignition device can also be arranged in the region of the perforated plate, designed to ignite a mass flow of combustion mixture exiting through the perforated plate. The burner can be arranged on a burner door of a combustion chamber of the heater. The burner door can have a flow-through opening that can connect the mixture channel of the heater to the burner cavity. A cylindrical burner can have a flange for attachment to the burner door, which can be connected to the burner door, for example, by means of a screw connection.A seal, such as a high-temperature-resistant graphite seal, is usually located between the burner and the burner door. The burner and flame arrester can be designed as a single unit. The burner is connected to the burner door via a seal made of graphite or a similar material.

[0013]

[0013] The burner can comprise (at least) one flame arrester, which is designed and arranged in the burner cavity such that combustion mixture flowing to the perforated plate must penetrate the flame arrester. In other words, the flame arrester can cover the entire existing flow cross-section in the burner cavity, so that combustion mixture flowing to the perforated plate must penetrate the flame arrester. For example, in a cylindrical burner, the flame arrester can also be cylindrical with a largely constant distance from the perforated plate. In a flat (planar) perforated plate, the flame arrester can also be flat and planar and arranged at a distance from the perforated plate in the burner cavity.

[0014] The flame arrester can incorporate (micro-)channels (e.g., with a channel cross-section smaller than 1 / 100, smaller than 1 / 1,000, or even smaller than 1 / 10,000 of the pipe cross-section itself), pore systems, or honeycomb structures, etc., within its interior, which allow the combustion gas to flow through their cross-section alone. The channel density or porosity of the flame arrester can be adapted to the flow or the combustion gas. "Channels" in this sense are, in particular, flow paths for the combustion mixture through the flame arrester, i.e., flow paths that extend from one inlet side (facing the mixture channel) to an opposite outlet side (facing the perforated plate). The channels can have a straight or directional (oblique, winding, etc.) course.If the flame arrester is designed with porosity, this refers in particular to the (irregular) formation of interconnected pores, which also allow flow from the inlet side to the opposite outlet side. Suitable materials or semi-finished products for the flame arrester are listed below as examples: open-pored (open-cell) ceramic or metal foams, expanded metals, in particular multi-layered and / or sintered, wire mesh, in particular multi-layered, fiber mats, optionally sintered, (correspondingly high-temperature-resistant) nonwovens.

[0015] The heater can also have a flame monitor that detects the presence of a flame at the burner and can interrupt the gas supply if the flame goes out. The flame monitor can detect whether or not a flame is present at the burner. A signal from the flame monitor can be used to regulate and control the heater, in particular to determine and regulate the combustion air ratio of the gas mixture. Various sensors can be used for flame monitoring. Ionization electrodes are often used to measure the ionization current of the flame. However, the combustion of hydrogen produces too few free charge carriers, which means that this method usually does not allow for robust flame detection in hydrogen-powered heaters. Temperature sensors are also known for flame detection.These can also be used by measuring the temperature-dependent resistance of a temperature sensor, such as a glow plug or hot-surface igniter. In particular, flame monitoring allows for inferences about the combustion air ratio (also known as lambda or air ratio) of the supplied combustion mixture of fuel gas and combustion air.

[0016] In particular, the heater can adapt the burner output to demand, a process also known as modulation. If a change in heat demand is detected, for example taking into account the flow and return temperatures of a heating circuit connected to the heater, a control unit in the heater can adapt the output of the heater's fan and thus the combustion air mass flow to the heat demand. At the same time, a control unit adapts the fuel mass flow to the changing combustion air mass flow. To avoid flashbacks in low power ranges, the combustion air ratio is often adjusted, particularly the proportion of combustion air. The associated increase in flow velocity and simultaneous reduction in flame speed (with the same heater output) can reduce the risk of flashbacks.Nevertheless, there is an increased risk of flashback occurring during a modulation process of the heater, which can be reduced by the present invention.

[0017] The heater may have a gas valve to control the fuel mass flow, which typically includes a gas safety valve and a gas control valve. The gas control valve may, in particular, be a stepper motor valve capable of setting a defined fuel mass flow. The safety valve is intended to prevent the escape of unburned fuel and is released, for example, during the heater start-up process, only after the feed system has been accelerated to a starting power suitable for the start-up process.

[0018] One idea of ​​the invention is to arrange the flame arrester in the flow path of the combustion mixture opposite the burner cavity and / or the burner door, forming a sealing area comprising a seal in such a way that the combustion mixture is forced to penetrate the flame arrester and secondary flows that could lead to a flashback into the mixture channel are prevented.

[0019] A sealing area can be understood as an area in which a sealed connection (especially for a hydrogen flame) is created between two components. The sealing connection in the sealing area can be formed by the two components themselves or by means of an additional seal.

[0020] The seal can in particular be a high-temperature stable seal, for example made of graphite, felt, NBR (nitrile rubber), mica, ceramic fiber paper (such as SiO2, AI2O3), temperature-resistant elastomers or a labyrinth seal with correspondingly small channels (gap dimensions).

[0021] According to one embodiment, a sealed connection can be formed between the burner and flame arrester on the side facing away from the burner door. For this purpose, for example (in the case of a cylindrical burner), a common cover for the flame arrester and burner body on which the outer surfaces (of the cylindrical shape) of the burner and flame arrester are arranged can be provided. Alternatively, the outer surfaces of the burner and flame arrester can also have separate covers, which can also be connected to one another, for example using a joining technique such as screwing, welding, or riveting. It would also be possible for a cover of the burner to be provided with a collar (for example connected to the cover by welding) for connection to the flame arrester.

[0022] According to one embodiment, the sealing area can be formed in the area of ​​the flow opening of the burner door. For a flame arrester with a cylindrical shape, for example, the cylindrical shape of the flame arrester could have an outer diameter that is slightly smaller than the inner diameter of the flow opening, so that the flame arrester can be inserted into the flow opening during assembly. For example, a seal, such as a shaft seal or a stuffing box packing, could be arranged circumferentially in the flow opening, which can create a sealed connection between the burner door and the flame arrester.

[0023] A stuffing box packing (also known as a gland packing) is a seal that is compressed by a mechanical action during assembly (inserting the flame arrester into the flow opening), thereby forming a tight connection. The mechanical action could, in particular, consist of an axial force during assembly, for example, by fastening (screwing) the burner to the burner door. To improve the sealing effect, an additional O-ring can be inserted in the area of ​​the compression. The O-ring can compress the stuffing box, particularly when fastening the burner (for example, using a burner flange), and create a tight connection with a high degree of reliability.

[0024] According to one embodiment, a groove can also be provided in the burner door, for example with a radius larger than the flow opening and concentric to the latter. The flame arrester can be pushed into the groove during assembly and form a sealing area there. For this purpose, a seal can be arranged cumulatively in the groove, but an adequate sealing effect can also be achieved without a seal. Advantageously, a sealing area in the form of a labyrinth seal formed by the flame arrester and a formation (such as a groove) in the burner door is sufficiently tight for a hydrogen flame. This does not require any additional components (which could also be forgotten during assembly), and it can also prevent static overdetermination of the sealed connection.

[0025] According to one embodiment, the burner and flame arrester can be designed as a single unit. For this purpose, they can be connected, so that only one component needs to be installed during assembly into the burner door. This design also ensures that installation without a flame arrester (which can pose significant safety risks) can be avoided.

[0026] According to a further aspect, an arrangement of a burner and a flame arrester is also proposed, wherein the burner and flame arrester are connected and the burner has a fastening region for fastening to a burner door of a heating device and the flame arrester, in a state in which the burner is fastened to a burner door, is designed to form a sealing region with the burner door. For this purpose, particularly in the case of a cylindrical burner, a likewise cylindrical flame arrester can be designed to be longer than the burner itself, so that the flame arrester can engage in the flow opening or a groove in the burner door as a sealing region. In particular, the flame arrester and burner door can form a sealing region independent of the burner seal (seal between the burner and the burner door).This independent sealing area can in particular be arranged upstream of the burner seal (seen in a flow direction of the heater).

[0027] According to a further aspect, the use of a seal for sealingly connecting a burner door and a flame arrester is proposed.

[0028] The details, features, and advantageous embodiments discussed in connection with the heater may also be present in the arrangement and use presented here, and vice versa. In this respect, reference is made in full to the explanations therein for a more detailed characterization of the features.

[0029] Thus, a heater, an arrangement of a burner and a flame arrester, and a use are provided here that at least partially solve the problems described with reference to the prior art. In particular, the heater, the arrangement, and the use at least contribute to preventing flashbacks.

[0030] In addition, the invention requires only minor structural changes to a heater and can be easily integrated into an existing production process.

[0031] The solution proposed here creates, in particular, a second sealing level so that the burner seal and the flame arrester seal are independent of each other and form a redundant system that increases safety.

[0032] The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments cited. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description. In particular, it should be noted that the figures, and in particular the proportions shown, are only schematic. They show: Fig. 1: a heating device proposed here, Fig. 2: an arrangement of a burner and a flame arrester proposed here, and Fig. 3: an alternative embodiment of an arrangement of a burner and a flame arrester proposed here.

[0033] Fig. 1 shows, by way of example and schematically, a heating device 1 proposed here. This can comprise a burner 3 arranged in a combustion chamber 8. Combustion air can be sucked in via a combustion air supply 4 by a conveying device 2, in particular designed as a fan. The conveying device 2 can be connected to a speed controller 6, which can regulate a speed n of the conveying device 2 by means of a pulse width modulated (PWM) signal. A gas valve 5 can add fuel gas from a gas supply 14 to the sucked-in air mass flow of combustion air and can comprise a safety valve and a gas control valve for controlling the mass flow of fuel gas to be added. The generated combustion mixture of fuel gas and combustion air can flow via a mixture channel 11 to the burner 3 and be ignited there by an ignition device.Heat generated during combustion can be transferred by means of a heat exchanger 12, for example to a heat carrier of a heating circuit.

[0034] The burner 3 may have a cylindrical shape, which may be attached by a base surface to a burner door 15 such that combustion mixture can flow from the mixture channel through a flow opening 19 into a burner cavity 25 arranged in the burner 3. After combustion, the combustion products can be discharged to the outside via an exhaust pipe 9 of the heater and an exhaust system 10.

[0035] The heater 1 proposed here can be configured, in particular, for the combustion of hydrogen. Furthermore, the heater 1 can have a flame monitoring device 13 on or in the burner door 15, which can be configured here as a sensor for UV (ultraviolet) radiation emitted by the flame.

[0036] A control and regulation device 7 can be configured to regulate the heater 1. For this purpose, it can be electrically connected, for example, to the speed control 6, the conveyor device 2, the gas valve 5, and the flame monitoring device 13 (Internet).

[0037] Fig. 2 shows, by way of example and schematically, an arrangement 16 proposed here of a burner 3 and a flame arrester 18, which can be fastened to a burner door 15. A flange 22 can be provided for fastening, wherein a burner seal 23 between the flange 22 and the burner door 15 can prevent combustion mixture from escaping from the connection area between the burner 3 and the burner door 15. The burner 3 can have a cylindrical shape, wherein the outer surface of the cylinder can be designed as a perforated plate 17. A flame arrester 18 can be arranged in the burner cavity 25, which can also have a cylindrical shape and can be arranged concentrically and at a distance from the burner 3 or its perforated plate 17.The burner cavity 25 can be connected to the mixture channel 11 via a flow opening 19 of the burner door 15, so that combustion mixture can flow in a flow direction 24 from the mixture channel 11 through the flow opening 19 into the burner cavity 25 and, after penetrating the flame arrester 18, can exit through the perforated plate 17 and burn.

[0038] The flame arrester 18 can protrude into the flow opening 19 and form a sealing area 26 comprising a seal 20. In the Fig. 3 The seal 20 can, for example, be a shaft seal or a stuffing box packing. Due to the existing mechanical stability of the flame arrester 18, sufficient contact pressure can develop on the seal 20 so that, when the flame arrester 18 is inserted into the flow opening 19, a sealed connection can be established between the flame arrester 18 and the burner door 15 or the flow opening 19. Additionally, an O-ring 27 can be provided, which additionally compresses a seal 20 designed as a stuffing box when the flange 22 of the burner 3 is attached to the burner door 15.

[0039] Fig. 31 also shows, by way of example and schematically, an alternative embodiment of the arrangement 16 of the flame arrester 18 and burner 3, wherein a groove 21 can be arranged concentrically and spaced from the flow opening 19 in the burner door 15 on the side facing the combustion chamber 8. The flame arrester 18 can engage in this groove 21 and form a sealing area 26. Advantageously, a sealing area 26 with sufficient tightness can thus be formed in a simple manner, from which, moreover, no (significant) forces can act (directly) on the flame arrester 18. List of reference symbols

[0040] 1 Heater 2 Conveyor system 3 Burner 4 Combustion air supply 5 Gas valve 6 Speed ​​control 7 Control unit 8 Combustion chamber 9 Exhaust pipe 10 Exhaust system 11 Mixing duct 12 Heat exchanger 13 Flame monitoring 14 Gas supply 15 Burner door 16 Arrangement of burner and flame arrester 17 Perforated plate 18 Flame arrester 19 Flow opening 20 Seal 21 Groove 22 Flange 23 Burner seal 24 Flow direction 25 Burner cavity 26 Sealing area 27 O-ring

Claims

1. Heating device (1), comprising a burner (3) which is arranged on a burner door (15) and comprises a perforated plate (17) which is arranged between a burner cavity (25) and a combustion chamber (8) of the heating device, wherein the burner (3) comprises a flame arrester (18) arranged in the burner cavity (25) which is designed such that it forms a sealing area (26) with the burner door (15).

2. Heating device (1) according to claim 1, wherein the sealing region (26) is formed in a flow opening (19) of the burner door (15).

3. Heater (1) according to claim 2, wherein the sealing area has a seal (20).

4. Heater (1) according to claim 1, wherein the seal (20) is a stuffing box packing or a shaft seal.

5. Heating device (1) according to one of the preceding claims, wherein a groove (21) is provided in the burner door (15) into which the flame arrester (18) engages.

6. Heating device (1) according to claim 5, wherein the groove (21) in the burner door (15) is shaped so that it forms a labyrinth seal with the flame arrester (18).

7. Heating device (1) according to one of the preceding claims, wherein the burner (3) and flame arrester (18) are formed as a unit.

8. Heating device (1) according to one of the preceding claims, wherein the burner (3) has a cylindrical shape and is arranged with a base side on the burner door (15).

9. An arrangement (16) of a burner (3) and a flame arrester (18), wherein the burner (3) and the flame arrester (18) are connected and the burner (3) has a fastening area for fastening to a burner door (15) of a heating device (1) and the flame arrester (18), in a state in which the burner (3) is fastened to a burner door (15), is aligned to form a sealing area (26) with the burner door (15).

10. The assembly (16) of claim 9, wherein the sealing region (26) comprises a seal.

11. Use of a sealing area (26) formed by a flame arrester (18) and a burner door (15) for sealingly connecting a burner door (15) and a flame arrester (18).

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