EP4368885A1 - Heating device, assembly of a flame arrestor and a burner and use of a seal - Google Patents

Abstract

A heating device (1) is proposed, having a burner (3) arranged on a burner door (15), comprising a perforated plate (17) 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). In this way, a flashback can advantageously be prevented, since bypass flows of combustion mixture around the flame arrester (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 arrester (18) engages. In addition, an arrangement (16) of a burner (3) and a flame arrester (18) and the use of a seal (20) are proposed.

Description

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

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.

As part of the effort to avoid fossil fuels, hydrogen is becoming increasingly important as a fuel for heating devices. Due to the properties of hydrogen, in particular an increased flame speed, the risk of flashbacks increases when hydrogen is used as a fuel.

A flashback, also known as a backfire, is the spread of a flame on a burner against the flow direction of the combustion mixture into a mixture channel of the heater. Due to the accompanying pressure surge, a flashback can lead to considerable noise pollution and damage to the heater, especially the conveyor system.

For this purpose, the EP 3 974 719 A1 It is proposed to arrange a flame barrier between an air supply and a perforated plate of the burner, which cannot be penetrated by a flame. This can prevent further penetration of a flame into a mixture gas line of the heater. A similar design is also described in the EN 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.

The EP 3 751 196 A1 describes an alternative design of a flashback 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 fire from spreading into the mixture channel. The disadvantage is that the reaction time of the valve can allow a flame to pass through, and the valve is also maintenance-intensive due to moving parts.

Based on this, the object of the invention is to propose a heating device, an arrangement of a flame arrester and a burner and a use of a seal that at least partially overcomes the problems of the prior art described. In particular, flashbacks are to be robustly avoided.

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

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 reasonable manner and define further embodiments of the invention. In addition, the features specified in the patent claims are specified and explained in more detail in the description, with further preferred embodiments of the invention being presented.

A heating device contributes to this, having a burner arranged on a burner door, which comprises a flame arrester which is designed in such a way that it forms 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 in the same sealing plane or in particular in a second sealing plane of the burner seal.

The heating device is in particular a gas heating device that is 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 carrier of a heating circuit or to provide a hot water supply. In particular, the heating device can be a condensing boiler. The heating device generally has a combustion chamber and a conveying device or a fan that can convey a mixture of fuel and combustion air via a mixture channel into a combustion chamber in which a burner is arranged. The combustion products can then be fed to an exhaust system through an exhaust channel of the heating device.

The burner can comprise at least one flat perforated plate or a perforated plate in a cylindrical shape, which is 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 from the perforated plate and be burned there. In addition, an ignition device can be arranged in the area 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 opening that connects the mixture channel of the heater with the burner cavity. A cylinder-shaped burner can have a flange for attachment to the burner door, which can be connected to the burner door using a screw connection, for example. A seal, such as a high-temperature-stable graphite seal, is usually arranged between the burner and the burner door. The burner and the flame arrester can be designed as a unit. The burner is connected to the burner door using a seal made of graphite or a similar material.

[0013] The burner can comprise (at least) one flame arrester, which is designed and arranged in the burner cavity in such a way 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 the case of a burner designed in a cylindrical shape, the flame arrester can also be designed in a cylindrical shape with a largely constant distance from the perforated plate. In the case of a flat (level) perforated plate, the flame arrester can also be designed flat and level and arranged at a distance from the perforated plate in the burner cavity.

• offenporige (offenzellige) Keramik- oder Metallschäume,
• Streckmetalle, insbesondere mehrlagig und/ oder gesintert,
• Drahtgewebe, insbesondere mehrlagig,
• Fasermatten, gegebenenfalls gesintert,
• (entsprechend hochtemperaturbeständiges) Vliese.

The flame arrester can form (micro) channels (e.g. with a channel cross-section of less than 1/100 or less than 1/1,000 or even less than 1/10,000 of the line cross-section itself), pore systems, or honeycomb structures, etc. inside, which only allow fuel gas to flow through their cross-section. The channel density or porosity of the flame arrester can be adapted to the flow or the fuel 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 an inlet side (facing the mixture channel) to an opposite outlet side (facing the perforated plate). The channels can be straight or directed (slanted, winding, etc.). If the flame arrester is designed with porosity, this means in particular 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, especially multi-layered and/or sintered,
• Wire mesh, especially multi-layered,
• Fibre mats, optionally sintered,
• (correspondingly high temperature resistant) fleece.

The heater can also have a flame monitor that detects the presence of a flame on the burner and can interrupt the gas supply if the flame goes out. The flame monitor can detect whether or not there is a flame on 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 an ionization current of the flame. However, too few free charge carriers are produced when hydrogen is burned, which means that this method usually does not allow robust flame detection for hydrogen-powered heaters. Temperature sensors for flame detection are also known. These can also be used by measuring a temperature-dependent resistance of the temperature sensor, for example a glow plug or hot surface igniter. In particular, flame monitoring enables conclusions to be drawn about the combustion air ratio (also known as lambda or air number) of the supplied combustion mixture of fuel gas and combustion air.

The heater can in particular adapt the burner output to the requirement, which is also referred to as modulation. To do this, when a changed heat requirement is detected, for example taking into account a flow and return temperature of a heating circuit connected to the heater, a control and regulating device of the heater can adapt a power of the heater's fan and thus the combustion air mass flow to the heat requirement. At the same time, a control system 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, in particular the proportion of combustion air is increased. The associated increase in the flow velocity while simultaneously reducing the flame speed (with the same heater output) can reduce the risk of flashbacks. Nevertheless, when the heater is modulated, there is an increased risk of flashbacks occurring, which can be reduced by the present invention.

The heater can have a gas valve to control the fuel mass flow, which can generally include a gas safety valve and a gas control valve. The gas control valve can in particular be a stepper motor valve that can set a defined fuel mass flow. The safety valve is intended to prevent unburned fuel from escaping and is only released when the heater is started, for example, after the conveyor device has been started up to a starting power suitable for the starting process.

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.

A sealing area can be understood as an area in which a sealing connection (in particular 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.

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).

According to one embodiment, a sealing connection can be formed between the burner and the flame arrester on the side facing away from the burner door. For this purpose, for example (in the case of a burner with a cylindrical shape) a common cover of 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.

According to one embodiment, the sealing area can be formed in the area of the flow opening of the burner door. In the case of a flame arrester with a cylindrical shape, for example, the cylindrical shape of the flame arrester could have an outer diameter that is insignificantly smaller than the inner diameter of the flow opening, so that the flame arrester can be pushed into the flow opening during assembly. For example, a seal, such as a shaft seal or a stuffing box packing, could be arranged all around the flow opening, which can create a sealing connection between the burner door and the flame arrester.

A stuffing box packing (also known as a gland) is a seal that is compressed by a mechanical effect during assembly (inserting the flame arrester into the flow opening) and thereby forms a tight connection. The mechanical effect could consist in particular of a force acting in the axial direction during assembly, for example by fastening (screwing) the burner to the burner door. To improve the sealing effect, an O-ring can also 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.

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 it. 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 a sufficient sealing effect can also be achieved without a seal. 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 advantageously sufficiently tight for a hydrogen flame, whereby no additional components are necessary (which could also be forgotten during assembly) and static overdetermination of the sealing connection can also be avoided.

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 during assembly in The burner door is advantageously only one component that needs to be installed. This design is particularly advantageous in that it ensures that installation without a flame arrester (which can involve considerable safety risks) can be avoided.

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 area for fastening to a burner door of a heater and the flame arrester, in a state in which the burner is fastened to a burner door, is designed to form a sealing area with the burner door. For this purpose, in particular in the case of a cylinder-shaped 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 of the burner door as a sealing area. In particular, the flame arrester and burner door can form a sealing area that is 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).

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

The details, features and advantageous embodiments discussed in connection with the heater can also occur in the arrangement and use presented here and vice versa. In this respect, reference is made in full to the explanations there for a more detailed characterization of the features.

Here, a heating device, an arrangement of a burner and a flame arrester and a use are specified which at least partially solve the problems described with reference to the prior art. In particular, the heating device, the arrangement and use at least contribute to preventing flashbacks.

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

In particular, the solution proposed here creates 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.

Fig. 1:

ein hier vorgeschlagenes Heizgerät,

Fig. 2:

eine hier vorgeschlagene Anordnung eines Brenners und einer Flammensperre, und

Fig. 3:

eine alternative Ausgestaltung einer hier vorgeschlagenen Anordnung eines Brenners und einer Flammensperre.

The invention and the technical environment are explained in more detail below with reference to the attached figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments given. 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 size relationships shown are only schematic. They show:

Fig.1:

a heater suggested here,

Fig. 2:

an arrangement of a burner and a flame arrester proposed here, and

Fig. 3:

an alternative embodiment of the arrangement of a burner and a flame arrester proposed here.

Fig.1 shows an 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 supplied via a combustion air supply 4 through a conveyor device 2, in particular as 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 combustion air fuel gas from a gas supply 14 to the sucked-in air mass flow and can comprise a safety valve and a gas control valve for controlling the mass flow of fuel gas to be added. The combustion mixture produced from 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.

The burner 3 can have a cylindrical shape, which can be attached with a base to a burner door 15 in such a way 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.

The heating device 1 proposed here can be designed in particular for the combustion of hydrogen. In addition, the heating device 1 can have a (device for) flame monitoring 13 on/or in the burner door 15, which can be designed here as a sensor for UV (ultraviolet) radiation emitted by the flame.

A control and regulating device 7 can be set up to regulate the heating device 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).

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 attached to a burner door 15. A flange 22 can be provided for fastening, wherein a burner seal 23 between flange 22 and burner door 15 can prevent combustion mixture from escaping from the connection area between burner 3 and burner door 15. 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 burner 3 or its perforated plate 17. Burner cavity 25 can be connected to mixture channel 11 via a flow opening 19 in burner door 15, so that combustion mixture can flow in a flow direction 24 from mixture channel 11 through flow opening 19 into burner cavity 25 and, after penetrating flame arrester 18, can exit through perforated plate 17 and burn.

The flame arrester 18 can extend into the flow opening 19 and form a sealing area 26 comprising a seal 20. In the Fig.3 the seal 20 can be, for example, a shaft seal ring or a stuffing box packing. Due to the existing mechanical stability of the flame arrester 18, sufficient contact pressure can be formed on the seal 20 so that when the flame arrester 18 is pushed into the flow opening 19, a sealing connection can be established between the flame arrester 18 and the burner door 15 or the flow opening 19. In addition, 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.

Fig.3 also shows, by way of example and schematically, an alternative embodiment of the arrangement 16 of flame arrester 18 and burner 3, wherein a groove 21 can be arranged concentrically and at a distance 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. In this way, a sealing area 26 with sufficient tightness can advantageously be formed in a simple manner, from which no (significant) forces can act (directly) on the flame arrester 18.

List of reference symbols

1

heater

2

Conveyor system

3

burner

4

Combustion air supply

5

Gas valve

6

Speed control

7

Control and regulation device

8th

Combustion chamber

9

Exhaust pipe

10

Exhaust system

11

Mixture channel

12

Heat exchanger

13

Flame monitoring

14

Gas supply

15

Burner door

16

Arrangement of burner and flame arrester

17

Perforated sheet

18

Flame arrester

19

Flow opening

20

poetry

21

Groove

22

flange

23

Burner seal

24

Flow direction

25

Burner cavity

26

Sealing area

27

O-ring

Claims (11)

Heating device (1), having 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 region (26) with the burner door (15). Heating device (1) according to claim 1, wherein the sealing region (26) is formed in a flow opening (19) of the burner door (15). Heater (1) according to claim 2, wherein the sealing region comprises a seal (20). Heater (1) according to claim 1, wherein the seal (20) is a stuffing box packing or a shaft sealing ring. 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. Heating device (1) according to claim 5, wherein the groove (21) in the burner door (15) is shaped such that it forms a labyrinth seal with the flame arrester (18). Heating device (1) according to one of the preceding claims, wherein the burner (3) and flame arrester (18) are formed as a unit. 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). 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). Arrangement (16) according to claim 9, wherein the sealing region (26) comprises a seal. Use of a sealing area (26) formed by a flame arrester (18) and a burner door (15) for the sealing connection of a burner door (15) and a flame arrester (18).

Images