Heating device, method for operating a heating device and computer program

Abstract

Proposed is a heater (10) configured to combust a combustion mixture comprising a fuel gas with a hydrogen content of at least 80 percent and combustion air. The combustion mixture is conveyed by means of a conveying device (6) through a mixture channel (7) into a burner cavity (23) of a burner (1) and exits through a burner outlet element (4) into a combustion chamber (3) where it burns. A device for selectively adjusting the flow resistance (5) is arranged in the mixture channel (7) or in the burner cavity (23). The heater (10) enables noise-free operation of the heater (10) in all operating ranges.

Description

[0001] The invention relates to a heater, a method for operating a heater, and a computer program. The heater is designed to burn hydrogen.

[0002] Hydrogen combustion in heating appliances is becoming more of a focus for the general public, especially for domestic heating appliances for heating and / or hot water production.

[0003] The combustion of hydrogen differs significantly from the combustion of fossil fuels. In addition to an increased probability of flashbacks, which can be mitigated, for example, by a flame arrester, the combustion of hydrogen can also produce disturbing noises. The cause of this could be flame instability in hydrogen flames, which can occur under certain operating conditions.

[0004] Noise-free operation is often not possible, particularly during the ignition process of a hydrogen-powered heater.

[0005] DE 10 2022 102 753 A1 describes a method for starting up a heater and a heater. The effects of gusts of wind or an at least partially blocked exhaust duct on the ignition process can be reduced by means of a throttle device, which can be arranged, among other things, in the mixture duct.

[0006] DE 20 2013 105 011 U1 discloses a control device for a burner device with a throttle device in the gas supply.

[0007] DE 103 24 706 B3 and DE 693 15 459 T2 describe mixing devices and gas dosing devices for combustion systems, which, however, are not suitable for the combustion of hydrogen.

[0008] The object of the invention is therefore to at least partially alleviate or solve the problems described with reference to the prior art. In particular, a heater is to be provided that enables noise-free operation in all operating situations and is durable.

[0009] In addition, the invention is intended to increase the complexity of a heating device at least only insignificantly and, if necessary, it should also be possible to easily retrofit existing heating devices with the invention.

[0010] 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.

[0011] This is achieved by a heater designed to burn a combustion mixture consisting of a fuel gas with a hydrogen content of at least 80 percent and combustion air. The combustion mixture is conveyed by means of a conveying device through a mixture channel into a burner cavity and then through a burner outlet element into a combustion chamber, where it is burned. It is proposed that a device for specifically adjusting the flow resistance be arranged in the mixture channel or in the burner cavity.

[0012] The device for targeted adjustment of the flow resistance can generate a flow resistance in the mixture channel and / or in the burner cavity and thus cause a pressure drop. Targeted adjustment comprises the flow resistance being able to be increased and / or reduced selectively or in a predeterminable manner before, during and / or after operation of the heater. In particular, the adjustment can comprise a structural change to the mixture channel and / or the burner cavity so that the geometry of the flow area can be changed, i.e. the flow area can be (at least partially) enlarged, blocked, divided, covered, etc. The device for adjusting the flow resistance can have a zero position in which there is largely no pressure drop in the area affected by the device for adjusting the flow resistance.The pressure drop is selected in such a way that noise from the heater is prevented. The pressure drop required for this can be determined, for example, in laboratory tests on a reference heater and thus specified. In particular, a flow resistance or pressure drop can be set depending on the heater's output or for specific operating conditions.

[0013] The heater can be used to supply a building with heat and / or hot water and can be installed either wall-mounted or floor-standing. In particular, the heater can provide a heat output of up to 50 kilowatts.

[0014] The heater can draw in a mass flow of combustion air via an air supply by means of a conveying device, to which a mass flow of combustion gas corresponding to a predetermined combustion air ratio, also known as lambda or air ratio, is added. The resulting combustion mixture can be fed to a burner via a mixture duct, where it can flow into a burner cavity, then exit through a burner outlet element into a combustion chamber and be combusted there. For this purpose, the heater can comprise an ignition device to ignite the combustion mixture at the burner outlet element. The combustion products can then be fed to a building's exhaust system via an exhaust duct of the heater.

[0015] To control the fuel gas mass flow, the heater can have a gas valve, which can usually 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 gas mass flow. Alternatively, the gas control valve can also deliver a fuel gas mass flow according to a transmitted control pressure. The control pressure can be recorded in a Venturi device and can be a measure of the delivered combustion air mass flow. This design is also referred to as a pneumatic gas-air connection. The safety valve is intended to prevent the escape of unburned hydrogen and is released, for example, during a heater start-up process only after the delivery device has started up to a starting power suitable for the start-up process. The aforementioned components can all be parts of the heater itself.

[0016] In particular, the heater can adjust the burner output to the demand, a process also known as "modulation." When 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 of the heater can adjust the heater fan output and thus the combustion air mass flow to the heat demand. At the same time, a control system adjusts the fuel gas mass flow to the changing combustion air mass flow.

[0017] The burner can comprise at least one burner cavity and a burner outlet element through which the combustion mixture can exit into a combustion chamber for combustion. The burner cavity can also have a burner hood, which often contains an inlet for the combustion mixture. In a cylindrical burner, the burner hood often consists of a burner door, which also defines the combustion chamber. In a flat burner or a burner with a flat burner outlet element, the burner hood can separate the burner cavity from the surroundings.

[0018] The burner outlet element can have a cylindrical or, in particular, flat shape. The burner outlet element comprises a plurality of openings through which the combustion mixture can flow. A burner outlet element is often also referred to as a perforated plate. During normal operation of the heater, the combustion mixture exits through the burner outlet element and burns in the combustion chamber. A flame region forms downstream of the burner outlet element, as seen in the direction of flow.

[0019] The combustion chamber may comprise one or more heat exchangers that can transfer heat generated during combustion to a heat transfer medium circulating in a heating circuit or to domestic water. The heater may, in particular, be a condensing heater, also known as a condensing boiler, in which the exhaust gas is cooled to a temperature that allows the condensation heat of the water vapor contained in the exhaust gas to be utilized. For example, a primary heat exchanger may be arranged at least partially in or on a wall of the combustion chamber, thus enabling the transfer of heat from the exhaust gas stream as well as the thermal radiation from the flame to a heat transfer fluid.

[0020] The heater is designed to burn a fuel gas with a (pure) hydrogen content of at least 80 percent. In particular, the heater can be designed to burn a fuel gas with a content of at least 90 or 95 percent, or even largely pure hydrogen.

[0021] Such a heater can be started up by increasing the feed system to a starting power at which the gas valve opens and adds a gas flow corresponding to a predetermined combustion air ratio. The heater can then be ignited, during which the ignition device is activated and ignites the combustion mixture emerging from the combustion outlet element. Flame formation can be accompanied by undesirable noise, particularly during the combustion of hydrogen. It has been found that this noise can be prevented by a deliberately generated and predetermined pressure drop in the mixture channel or in the burner cavity. The starting power at which ignition operation occurs is generally in a range of 15 percent to 45 percent of the nominal power of a hydrogen-powered heater.

[0022] According to one embodiment, the device for adjusting the flow resistance can comprise a counterforce device. This can counteract a force caused by the flow through the device for adjusting the flow resistance, and the resulting force can adjust a flow resistance of the device for adjusting the flow resistance. For example, the counterforce device can be a spring, and the counterforce can be a spring force of the spring.

[0023] According to one embodiment, the counterforce device can be a weight whose weight counteracts a force caused by the flow through the device for adjusting the flow resistance. The force caused by the flow can, for example, be an opening force of a flap of the device for adjusting the flow resistance. It is understood that the effective direction of the weight force must correspond to the installation position of the device for specifically adjusting the flow resistance. This embodiment can thus be particularly easy to implement in a region of the mixture channel that is vertically aligned in the installed position.

[0024] According to one embodiment, the device for adjusting the flow resistance can comprise a flap that can be arranged in the mixture channel. The flap can, for example, be a check valve, which could advantageously mitigate the effects of flashback. The flap can be mounted so as to be rotatable about a rotation axis, and the counterweight can be arranged on the side of the rotation axis facing away from the flap, so that the weight counteracts an opening force of the flap caused by the flow. In this way, an increase in the flow resistance of the device for adjusting the flow resistance can be achieved in a purely mechanical manner in lower power ranges. Increased noise generation in lower power ranges can thus be prevented.

[0025] According to one embodiment, the device for adjusting the flow resistance can be electrically controlled or adjustable. The electrical control can operate a stepper motor or a valve of the device for adjusting the flow resistance.

[0026] According to one embodiment, the device for adjusting the flow resistance can be configured to adjust the flow resistance as a function of a detected pressure.

[0027] According to one embodiment, the detected pressure can be a differential pressure. This can, for example, be between the burner cavity and a point within the heater housing outside the burner cavity or the burner hood. In this case, an air supply of the heater can end within the housing, thus drawing the combustion air from the heater housing. For this purpose, the housing can be connected to an air supply line, which, for example, runs at least partially concentrically to the exhaust system.

[0028] According to one embodiment, the differential pressure can be pneumatically adjusted to a flow resistance of the flow resistance adjustment device. The differential pressure can thus be used for pneumatic control of the flow resistance adjustment device.

[0029] According to one embodiment, the device for adjusting the flow resistance can be a flap with an adjustable opening width or an adjustable throttle device. The adjustable throttle device can be, for example, a Venturi nozzle with an adjustable nozzle geometry. These embodiments are suitable for electrical control, for example, by means of a stepper motor.

[0030] According to one embodiment, the device for adjusting the flow resistance can be arranged within the burner cavity and aligned (largely) parallel to the burner outlet element.

[0031] According to a further embodiment, a part of the device for adjusting the flow resistance can be movable in a flow direction through the heater or in a direction perpendicular to the flow direction, thus adjusting the flow resistance. This embodiment can be particularly suitable for arranging the device for adjusting the flow resistance in the burner cavity.

[0032] According to one embodiment, a part of the device for adjusting the flow resistance can be movable in the flow direction and increase the flow resistance by approaching the burner outlet element or another component through which fluid flows. To support this, the movable part of the device for adjusting the flow resistance can also have a pattern of flow openings that are at least partially non-aligned / congruent with the flow openings of the burner outlet element.

[0033] According to one embodiment, at least two parts of the device for adjusting the flow resistance in the combustion cavity can be arranged perpendicular to the flow direction and thus largely parallel to the burner outlet element. By moving at least one part in a direction perpendicular to the flow direction, partial overlap of the at least two parts can be achieved, thus adjusting the flow resistance. This embodiment is very well suited for pneumatic control.

[0034] The concepts and modes of action described here for adjusting the flow resistance can be used or implemented alternatively or cumulatively with each other.

[0035] According to a further aspect of the invention, a method for operating a heater proposed here is proposed, in which, when an operating event occurs and / or depending on at least one operating parameter which allows a conclusion to be drawn about a performance of the heater, a predetermined flow resistance is set by means of the device for setting the flow resistance.

[0036] According to one embodiment, the at least one operating parameter can be selected from the following group: a speed of a conveying device designed as a blower, a control signal of a speed control of the conveying device, a detected pressure or differential pressure and / or a sensor-detected mass flow of combustion air, fuel gas or combustion mixture.

[0037] According to one embodiment, an operating event can be the ignition operation of the heater. Noise generation during ignition operation can be prevented by increasing the pressure drop of the device for adjusting the flow resistance.

[0038] According to a further aspect of the invention, a computer program (product) is proposed. This program comprises commands that cause a heating device proposed here to execute a method proposed here. The device for adjusting the flow resistance is electrically controllable for this purpose. The computer program can be executed, in particular, on a control and regulation device of a heating device.

[0039] The details, features, and configurations discussed in connection with the heater may also occur in a method and computer program proposed here, and vice versa. In this respect, the features relating to the heater may also be used to characterize the method or the computer program, and vice versa.

[0040] Thus, a heater, a method for operating a heater, and a computer program are provided that at least partially solve the problems described with reference to the prior art. In particular, the heater, the method, and the use at least contribute to largely completely eliminating combustion noise from a hydrogen-powered heater in a particularly simple manner.

[0041] In addition, the invention requires hardly any structural modifications to a heater and is very suitable for retrofitting to existing heaters.

[0042] 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 heater proposed here, Fig. 2 : a design of a heating device proposed here, Fig. 3 : a parameter curve that can be set for a heater proposed here, Fig. 4 und 5 : further embodiments of a heating device proposed here, Fig. 6 : another parameter curve that can occur with a heater proposed here, Fig. 7 : a detailed representation of a device for adjusting the flow resistance.

[0043] Fig. 1 shows, by way of example and schematically, a heater 10. This can comprise a burner 1 arranged at least partially in a combustion chamber 3. Combustion air can be sucked in from the environment via an air supply 13 in a flow direction 15 by means of a conveying device 6, which is designed here as a fan. The conveying device 6 can have an electric motor as a drive, which can be connected to a speed controller 9, which can regulate a speed of the conveying device 6 by means of a pulse width modulated (PWM) signal. A gas valve 12 can add fuel gas (here hydrogen) from a fuel gas supply 11 to the sucked-in air mass flow and can comprise a safety valve and a fuel 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 7 to the burner 1 and be ignited there by an ignition device.Heat generated during combustion can be transferred, for example, to a heat transfer medium of a heating circuit by means of a heat exchanger 19. After combustion, the combustion products can be discharged to the outside via an exhaust duct 18 arranged in the heater 10 and an exhaust system 17 in the flow direction 15.

[0044] The burner outlet element 4 of the burner 1 can be as in Fig. 1 shown, have a cylindrical shape, which can be attached with a base surface to a burner door as a burner hood 2 such that combustion mixture can flow from the mixture channel 7 into the burner hood 2 and thus the burner cavity 23. The burner 1 comprises a burner hood 2, a burner cavity 23, to which the combustion mixture is supplied from the mixture channel 7 and exits via a burner outlet element 4 into the combustion chamber 3 and burns to form a flame region 16.

[0045] The heater 10 shown here is configured for the combustion of hydrogen. Furthermore, the heater 10 can have a (device for) flame monitoring 14, which can be configured, for example, as an electrode for measuring ionization current. Alternatively or additionally, another sensor, e.g., a thermal, optical, acoustic, or chemical sensor, can be provided to fulfill the function of flame monitoring 14. The use of a sensor for UV (ultraviolet) radiation emitted by the flame has proven particularly suitable for flame monitoring 14 of a flame region 16 of hydrogen combustion.

[0046] A control and regulation device 8 can be configured to regulate the heater 10. For this purpose, it can be electrically connected, for example, to the speed control 9, the conveying device 6, the gas valve 12, the flame monitoring device 14, and the device for adjusting the flow resistance 5.

[0047] Fig. 2 shows, by way of example and schematically, an embodiment of a heater 10 with a largely flat burner outlet element 4. The mass flow of combustion mixture conveyed by the conveying device 6 can flow through the mixture channel 7 into the burner cavity 23, from there exit through the burner outlet element 4 and burn to form a flame region 16. The device for adjusting the flow resistance 5 can be arranged here in the burner cavity 23 and can be movable in a first direction of movement 20, which is largely aligned in the flow direction 15. By moving the first direction of movement 20, the device for adjusting the flow resistance 5 can reduce the distance to the burner outlet element 4 and thereby increase the flow resistance. A movement of the device for adjusting the flow resistance 5 can be electrically controlled by means of a stepper motor.

[0048] Fig. 3 shows parameter curves of a pressure drop Δp of a heater 10 over the modulation Mod, which is specified as a percentage [%] of the nominal power of the heater 10. On the abscissa axis, a minimum power 27, a power 28 at which ignition operation is initiated, and a nominal power 29 of the heater 10 (usually 100 percent) are marked. A first curve 25 shows the curve of the pressure drop Δp without a device for adjusting the flow resistance 5. The second curve 26 shows the curve of the pressure drop Δp with a device for adjusting the flow resistance 5 according to Fig. 2 The electrical control of the flow resistance adjustment device 5 enables a targeted influence on the flow resistance and thus on the pressure drop Δp. Thus, an increase in the pressure drop Δp can occur exclusively during ignition operation as an operating event. This makes it possible to control the pressure drop Δp during ignition operation from a first pressure drop 30 to a second pressure drop 31, thereby preventing any noise generation during ignition operation.

[0049] Fig. 4 shows, by way of example and schematically, an embodiment of the heating device 10 with a device for adjusting the flow resistance 5 arranged in the burner cavity 23, which is movable in a second direction of movement 21. The second direction of movement 21 is aligned perpendicular to the flow direction 15. The device for adjusting the flow resistance 5 can comprise a first part 32 and a second part 33, which can be arranged at least partially overlapping by a movement in the second direction of movement 21, whereby a flow resistance of the device for adjusting the flow resistance 5 can be adjusted. Fig. 4 The configuration shown is suitable for pneumatic control by means of a differential pressure. This can, for example, be between the burner cavity 23 and a detection point within the housing of the heater 1, outside the combustion chamber 3 and outside the burner cavity 23.

[0050] Fig. 5 shows, by way of example and schematically, a further embodiment of the heater 10, in which the device for adjusting the flow resistance 5 can be designed as a flap 22 in the mixture channel 7. A flow resistance of the device for adjusting the flow resistance 5 can be adjusted by adjusting the opening width of the flap 22.

[0051] Fig. 6 shows a possible design of the flap 22. This can be mounted rotatably about a rotation axis 34. A counterforce device 24, here designed as a counterweight, can cause a closing force on the flap 22. An opening of the flap 22 is caused when a flow through the flap 22 in the flow direction 15 causes an opening force on the flap 22 that is greater than the closing force applied by the counterforce device 24. The Fig. 6 The purely mechanical solution shown is ideal for retrofitting.

[0052] Fig. 7 shows parameter curves of the pressure drop over the modulation Mod of the heater 10, which are obtained when the heater 10 is designed according to Fig. 4 oder Fig. 5 For example, the device for adjusting the flow resistance 5 in Fig. 4 und 5 an increase in the second curve 26, i.e., the pressure drop of the flow resistance adjustment device 5, in a lower modulation range up to a limit modulation 35. In the range of the limit modulation 35, the flow resistance adjustment device 5 can open completely or reach a zero position, so that the second curve 26 can correspond to the first curve 25.

[0053] . List of reference symbols

[0054] 1 Burner 2 Burner hood 3 Combustion chamber 4 Burner outlet element 5 Device for adjusting the flow resistance 6 Conveying device 7 Mixture channel 8 Regulating and control unit 9 Speed control 10 Heater 11 Fuel gas supply 12 Gas valve 13 Air supply 14 Flame monitoring 15 Flow direction 16 Flame area 17 Exhaust system 18 Exhaust channel 19 Heat exchanger 20 First direction of movement 21 Second direction of movement 22 Flap 23 Burner cavity 24 Counterforce device 25 First course 26 Second course 27 Minimum power 28 Power during ignition operation 29 Nominal power 30 First pressure drop 31 Second pressure drop 32 First part 33 Second part 34 Rotation axis 35 Limit modulation

Claims

1. Heating device (10) designed to burn a combustion mixture of a fuel gas with a hydrogen content of at least 80 percent and combustion air, which mixture is passed by means of a conveying device (6) through a mixture channel (7) into a burner cavity (23) of a burner (1) and further exits through a burner outlet element (4) into a combustion chamber (3) and is burned, wherein a device for the targeted adjustment of the flow resistance (5) is arranged in the mixture channel (7) or in the burner cavity (23).

2. Heating device (10) according to one of the preceding claims, wherein the device for adjusting the flow resistance (5) comprises a counterforce device (24) which counteracts a force caused by the flow through the device for adjusting the flow resistance (5) and the resulting force sets a flow resistance or pressure drop of the device for adjusting the flow resistance (5).

3. Heating device (10) according to one of claims 1 or 2, wherein the device for adjusting the flow resistance (5) is electrically controllable.

4. Heating device (10) according to one of the preceding claims, wherein the device for adjusting the flow resistance (5) is designed to adjust the flow resistance as a function of a detected pressure.

5. A heater (10) according to claim 3, wherein the sensed pressure is a differential pressure between the burner cavity (23) and a sensing point within a housing of the heater (1) and outside the burner cavity (23).

6. Heating device according to claim 4 or 5, wherein the differential pressure pneumatically adjusts a flow resistance of the flow resistance adjustment device (5).

7. Heating device (10) according to one of the preceding claims, wherein the device for adjusting the flow resistance (5) is a flap (22) with an adjustable opening width or an adjustable throttle device.

8. Heating device (10) according to one of the preceding claims, wherein the device for adjusting the flow resistance (5) is arranged within the burner cavity (23) and is aligned parallel to the burner outlet element (4).

9. Heater (10) according to claim 8, wherein at least a part of the device for adjusting the flow resistance (5) is movable in a first direction of movement (20) in the flow direction (15) of the heater (10) or in a second direction of movement (21) perpendicular to the flow direction (15) and thus the flow resistance is adjustable.

10. A method for operating a heater (10) according to one of the preceding claims, wherein upon the occurrence of an operating event and / or depending on at least one operating parameter which allows a conclusion to be drawn about a performance of the heater (10), a predetermined flow resistance is set by means of the device for setting the flow resistance (5).

11. The method according to claim 10, wherein the at least one operating parameter is selected from the following group: - a speed of a conveying device (6) designed as a fan, - a control signal of a speed control of the conveying device (6), - a detected pressure or differential pressure, and / or - a sensor-detected mass flow of combustion air, fuel gas or combustion mixture.

12. The method according to claim 10 or 11, wherein an operating event is an ignition operation of the heater (10).

13. A computer program comprising instructions that cause a heating device (10) according to one of claims 2 to 9 to carry out a method according to one of claims 10 to 12.

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