Method for validating a signal from a flame monitoring device of a heater, computer program, storage medium, control and regulation device, heater and use of a temperature sensor

Description

[0001] The invention relates to a method for validating a signal of a device for flame monitoring of a heater, a computer program, a storage medium, a control and regulating device, a heater and a use of a temperature sensor.

[0002] Gas-fired heaters often feature a flame detection device that prevents unburned fuel gas-air mixture from escaping into the heater's combustion chamber. The flame detection device allows the gas supply to the heater to be interrupted as soon as the flame detection device can no longer detect a flame, thus enabling particularly safe operation of the heater.

[0003] DE 10 2012 220 526 B3 proposes a method for flameout detection in a fuel-powered vehicle heater. A gradient of a temperature variable related to the combustion state in the burner area and a model gradient based on an energy balance of the temperature variable are determined. A comparison can be used to detect flameout. This method is not suitable for validating a signal from a flame monitoring device in a heater.

[0004] EP 0 331 918 A2 also relates to a method for operating a heater, in particular a vehicle auxiliary heater, in which the air / fuel ratio is determined based on a flame temperature measured in the combustion chamber. A control system can change the combustion air and / or fuel supply quantity such that a predetermined target value for the air / fuel ratio and a corresponding target value for the flame temperature are achieved. This method is also unsuitable for validating a signal from a flame monitoring device.

[0005] DE 10 2019 119 186 A1 relates to a method and a device for controlling a fuel gas-air mixture in a heater. The speed of a fan is regularly varied while observing an ionization signal from the combustion process, with the position of the fuel gas valve held constant, in order to control or determine a combustion lambda value. If a first ionization measurement fails, it is proposed to use a second ionization measurement from an existing flame monitoring electronics system as an emergency control, on which the proposed method can be implemented. However, the proposed ionization measurement cannot be used to control the lambda value in hydrogen-powered heaters. EP 3 663 648 A1 discloses a method for controlling a hydrogen-powered heater. Redundant UV sensors are used to analyze the flame radiation.

[0006] EP 4 141 322 A1 is a document pursuant to Art. 54(3) EPC and discloses a method for validating a flame monitoring signal from a UV sensor in a hydrogen-powered heater. Validation is performed using the signal from an ionization electrode.

[0007] Heaters designed to burn hydrocarbons often use flame detection based on a measured ionization current of the heater's flame. This determines the charge carriers released during combustion. This method enables safe and reliable flame detection.

[0008] It was found that in hydrogen-powered heaters, flame detection based on the detection of an ionization current of the flame is not easily possible, especially at low heater power, because a hydrogen flame may release considerably fewer charge carriers than a flame from the combustion of hydrocarbons (e.g. natural gas).

[0009] Therefore, hydrogen-powered heaters can use flame detection based on UV light, with an ultraviolet light sensor directed at the flame. However, if the UV sensor fails and / or becomes contaminated, for example due to deposits of combustion products, reliable flame detection cannot be guaranteed, which would require the heater to be shut down.

[0010] A fault in a flame monitoring sensor and / or the evaluation electronics can be detected at the latest when a heater is put into operation, so that appropriate measures can then be initiated, such as taking the heater out of operation or putting it into error mode.

[0011] However, if a fault occurs in the sensors and / or the evaluation electronics of the flame monitoring system during operation of the heater, especially if the flame monitoring system continues to (incorrectly) indicate that the heater is flamed, the evaluation electronics cannot directly or reliably detect the fault. Should the heater flame actually go out in such a fault condition, unburned gas could escape, with corresponding consequences for the operational safety of the heater.

[0012] Based on this, the object of the invention is to propose a method for validating a signal from a flame monitoring device of a heater that at least partially overcomes the described problems of the prior art. In particular, it is intended to enable independent and reliable validation of the flame monitoring signal of a hydrogen-powered heater.

[0013] In addition, the invention should at least not significantly increase the complexity of a heating device and / or require only minor structural changes to a known heating device and / or enable easy integration into existing heating devices.

[0014] 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.

[0015] To this end, a method for validating a signal from a first flame monitoring device, which comprises a UV sensor, of a hydrogen-powered heater contributes, comprising at least the following steps: a) detecting a parameter which allows a conclusion to be drawn about the flame temperature of the heater, b) comparing the parameter detected in step a) with a reference range, c) operating the heater with a second flame monitoring device or switching off the heater if the parameter detected in step a) is outside a predetermined range.

[0016] In a regular process sequence, steps a), b), and c) are performed at least once in the specified order. In particular, steps a) and b) are performed continuously or at regular intervals during operation of the heater.

[0017] The method serves, in particular, to validate the signal of a first or primary (commonly used) flame monitoring device of a burner of a heater, and thus, in particular, to monitor the function of this first flame monitoring device. The first flame monitoring device comprises a UV sensor (sensor for detecting ultraviolet radiation from a flame) of the heater.

[0018] The heater is a gas heater designed to combust a gaseous fuel, such as hydrogen, with the addition of ambient air to generate heat, which can be provided, for example, to a heating circuit and / or a hot water supply. The heater typically has at least one burner and a conveying device (such as a fan) that conveys a mixture of fuel and combustion air through a mixture duct of the heater to the burner; the exhaust gas produced by the combustion can then be guided through an exhaust pipe of the heater to an exhaust system. Furthermore, the heater has at least one flame monitoring device. The flame monitoring device can be used to detect the presence of a flame or to regulate the combustion process.

[0019] The second or further flame monitoring device can, for example, be a device for measuring the ionization current of the heater's flame. The conductivity of the flame is measured, which varies with the amount of charge carriers released during combustion. In addition to detecting the presence of a flame, the measured ionization current can also be used to control the combustion process, in particular the mixture ratio of combustion air and fuel gas.

[0020] When hydrogen or a gas mixture containing hydrogen is burned, the flame has significantly lower ionization, at least at low heater power levels, making flame monitoring by measuring the ionization current more difficult. Therefore, alternative methods can be used, such as detecting the ultraviolet radiation (UV radiation) emitted by the flame. For this purpose, a UV sensor can be directed at the flame inside or outside the combustion chamber.

[0021] The reference value is usually given in the dimension of the parameter recorded in step a) and indicates a threshold at which, if reached, undershot, or exceeded, the flame is assumed to be extinguished. The reference value can, for example, be a discrete value stored in a data memory.

[0022] According to step a), a (selected) parameter of the heater is recorded, which allows a (preferably direct) conclusion to be drawn about a flame temperature. In particular, the parameter can be a temperature or a temperature difference.

[0023] According to an advantageous embodiment, the parameter to be detected in step a) can be a temperature to be detected in the combustion chamber and / or in the immediate vicinity of the combustion chamber. Detection can be carried out, in particular, by means of a temperature sensor.

[0024] According to a further advantageous embodiment, in step a), a temperature can be detected by a temperature sensor arranged in the combustion chamber, with the temperature sensor being as far away from the flame as possible. Advantageously, the temperature sensor should not be exposed to excessive temperatures, thus increasing its service life. It is understood that the reference value should be adapted to the position of the temperature sensor and the corresponding temperature range.

[0025] For the response time of the validation proposed here, it may be particularly advantageous to position the temperature sensor for performing step a) in the combustion chamber of the heater (as far away from the flame as possible), but in a position where it is directly exposed to the heat radiation of the flame. This advantageously prevents a time delay in detecting a flame loss due to the thermal mass of possible components located between the flame and the temperature sensor.

[0026] According to a further, possibly alternative, advantageous embodiment, a flow temperature of a heating circuit connected to the heater can be recorded as a parameter in step a). Advantageously, the flow temperature is regularly recorded in heaters anyway, and a method designed in this way is particularly easy to retrofit to existing heaters.

[0027] According to a further, possibly alternative, embodiment, a difference between the flow and return temperatures can be recorded as a parameter in step a). This can advantageously reduce the influence of the ambient temperature.

[0028] In step b), the parameter recorded in step a) is compared with a (specified) reference range. The reference range can also be defined using a specific reference value. If the reference range is defined by a reference value, this can be regarded as a limit value that determines whether a value of the parameter above or below this value lies within or outside the reference range. The reference range or reference value is, in particular, a temperature range or temperature and / or a temperature difference range or temperature difference. The reference range or reference value defines, in particular, an operating state of the heater in which, during regular operation of the heater, it can be assumed with a very high degree of certainty that the flame is extinguished.The evaluation of the temperature difference between the flow and return lines allows conclusions to be drawn about the heat energy supplied, particularly depending on the operating state of the heater.

[0029] According to a further advantageous embodiment, the reference range or reference value can be determined using operating data from the heater. The reference range or reference value can be determined once or online, meaning it can be adjusted permanently or regularly based on the operating data. The operating data to be included can be selected, for example, from the following group: heater output, flow and / or return temperature, fuel gas mass flow, and conveying system output.

[0030] According to a further advantageous embodiment, several parameters can also be recorded in step a), which allow a (direct) conclusion to be drawn about the flame temperature of the heater. For this purpose, several reference ranges or reference values ​​should be specified, which can be assigned to the corresponding recorded parameters.

[0031] In step c), if the comparison in step b) reveals that the parameter value is outside the reference range or falls below a reference value, the heater can be operated with a second flame monitoring device. If the heater does not have a second flame monitoring device, the heater can alternatively be shut down.

[0032] The second flame monitoring device can be of the same or different type and / or use a different measurement method than the first flame monitoring device. Advantageously, operation of the heater with a second flame monitoring device according to step c) can also be monitored by performing steps a) and b). For this purpose, one or more reference ranges or values ​​can be specified for the second flame monitoring device.

[0033] If no second (or additional) flame monitoring device is available, the heater can also be decommissioned in step c). To increase safety, the heater's gas supply can be closed. Furthermore, the heater can be advantageously put into a mode that prevents user operation and allows it only to be operated by a qualified person.

[0034] According to an advantageous embodiment, in a step d), the heater can provide or send information about the value of the parameter leaving a reference range or falling below or exceeding the reference value and / or a change in the flame monitoring device (result of step c)). In particular, the information can be provided or sent via a network, in particular the Internet. For example, after an automated shutdown or a change in the flame monitoring device, the heater can automatically send information about this to a selected specialist company, which can then plan and carry out a maintenance appointment for the heater to restore the first flame detection device.

[0035] According to a further aspect, a computer program is also proposed which is configured to (at least partially) carry out a method presented here. In other words, this relates in particular to a computer program (product) comprising instructions which, when executed by a computer, cause the computer to execute a method proposed here.

[0036] According to a further aspect, a machine-readable storage medium on which the computer program is stored is also proposed. The machine-readable storage medium is usually a computer-readable data carrier.

[0037] According to a further aspect, a control and regulating device for a heater is also proposed, configured to carry out a method proposed here. For this purpose, the control and regulating device can, for example, comprise and / or have a processor. In this context, the processor can, for example, execute the method stored in a memory (of the control and regulating device). Advantageously, data such as one or more reference ranges or reference values ​​for carrying out a method presented here can also be stored in the memory of the control and regulating device.

[0038] According to a further aspect, a hydrogen-powered heating device is also proposed, comprising a control and regulation device as proposed here. The gas heating device can have a burner and a conveying device with which a mixture of combustion gas (hydrogen) and combustion air can be supplied to the burner.

[0039] According to a further aspect, the use of a temperature of a heater detected in or in the immediate vicinity of a combustion chamber of a hydrogen-powered heater is proposed for validating a signal from a flame monitoring device of the heater.

[0040] The details, features, and advantageous embodiments discussed in connection with the method may also occur in the computer program, storage medium, control device, heater, and / or 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.

[0041] Thus, a method, a computer program, a storage medium, a control device, a heater, and a use are provided here that at least partially solve the problems described with reference to the prior art. In particular, the method, the computer program, the storage medium, the control device, the heater, and the use at least contribute to improving the operational reliability of a heater by providing a possibility for validating a detected signal from a flame monitoring device.

[0042] In addition, the invention can be carried out or implemented particularly easily and cost-effectively and, in particular, can also be retrofitted to existing heating devices.

[0043] As a precaution, it should be noted that the numerals used here ("first", "second", ...) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and therefore do not necessarily specify any interdependence and / or sequence of these objects, quantities, or processes. Should a dependence and / or sequence be required, this is explicitly stated here or will be obvious to the person skilled in the art upon studying the specifically described embodiment. To the extent that a component can occur multiple times ("at least one"), the description of one of these components may apply equally to all or part of the majority of these components, but this is not mandatory.

[0044] 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 sequence of a procedure proposed here, Fig. 2 : a heater proposed here, and Fig. 3 : a combustion chamber of a heating device proposed here.

[0045] Fig. 1 shows, by way of example and schematically, a sequence of a method proposed here. The method serves to validate a device for flame monitoring of a heater 1, for example, a UV sensor 12 or an ionization electrode 13. The sequence of steps a), b), and c) represented by blocks 110, 120, and 130 can occur during regular operation. In particular, however, a simultaneous (permanent) or regularly staggered execution of steps a) and b) may be appropriate.

[0046] In block 110, according to step a), a parameter is detected that allows a conclusion to be drawn about the flame temperature of the heater 1. For example, a temperature can be detected using a temperature sensor 10 arranged in a combustion chamber 8 of the heater 1.

[0047] In block 120, according to step b), the parameter recorded in step a) is compared with an assigned or determined limit value (as a reference range or reference value).

[0048] In block 130, according to step c), the heater 1 is operated with a second device for flame monitoring, for example the UV sensor 12 or the ionization electrode 13 (depending on which was previously active) or the heater is switched off if the parameter detected in step a) is, for example, smaller than the reference value.

[0049] Fig. 2 shows, by way of example and schematically, a heating device 1 proposed here. The heating device 1 can have a combustion air supply 4, to which combustion gas can be added via a gas valve 5. The resulting combustion mixture can be fed to a burner 3 arranged in a combustion chamber 8 via a mixture channel 16, in which a conveying device 2 can be arranged. Resulting combustion products can be discharged from the combustion chamber 8 via an exhaust system 9. At the bottom, the combustion chamber 8 can have a (condensate) drain 14, which can include a siphon 15.

[0050] The heater 1 can also have a control and regulation unit 7, which can be electrically connected to the temperature sensor 10, which is located in the combustion chamber 8 below the burner 3. By arranging the temperature sensor 10 below the burner 3 in the combustion chamber 8, it can be advantageously ensured that the burner is not exposed to excessively high temperatures.

[0051] The control unit 7 can also be electrically connected to the gas valve 5, the delivery device 2, and an ignition device 6. A method proposed here can advantageously be implemented on the control unit 7.

[0052] The heating device 1 can be connected to a heating circuit 18, comprising a flow line 19 and a return line 20, in which a heat transfer medium can circulate in a circulation direction 21. For this purpose, the heating circuit 18 can have a circulation pump (not shown here) and supply heat to consumers (not shown here). The temperature in the flow line 19 or the difference between the temperatures in the flow line 19 and the return line 20 can also be used as parameters to be recorded in step a).

[0053] Fig. 3shows, by way of example and schematically, a combustion chamber 8 of a heating device 1 proposed here. Combustion mixture can be fed to the burner 3 via the mixture channel 16 and combusted, forming a flame 11. The flame 11 can be monitored by a UV sensor 12 or the ionization electrode 13. The temperature sensor 10 can be arranged below the ionization electrode 13. The UV sensor 12, burner 3, ionization electrode 13, and temperature sensor 10 can be arranged in a burner door 17, which advantageously simplifies electrical cabling to the control unit 7. List of reference symbols

[0054] 1Heater 2Feeding device 3Burner 4Combustion air supply 5Gas valve 6Ignition device 7Regulating and control unit 8Combustion chamber 9Exhaust system 10Temperature sensor 11Flame 12UV sensor 13Ionization electrode 14Drain 15Siphon 16Mixing channel 17Burner door 18Heating circuit 19Flow 20Return 21Circulation direction

Claims

1. A method of validating a signal from a first flame monitoring device (12, 13), comprising a UV sensor (12), of a hydrogen fuelled heater (1), comprising at least the following steps: a) detecting a parameter that allows conclusions to be drawn about the temperature of a flame (11) of the heater (1) , b) comparing the parameter detected in step a) with a predetermined reference range, c) operating the heater (1) with a second device for flame monitoring or switching off the heater (1) if the parameter detected in step a) is outside a predetermined range.

2. Method according to claim 1, wherein the parameter detected in step a) is a temperature detected in the combustion chamber (8) or in the immediate vicinity of the combustion chamber (8).

3. Method according to claim 2, wherein the detection of a temperature according to step a) is carried out by a temperature sensor (10) in the combustion chamber (8).

4. Method according to claim 1, wherein in step a) a temperature of a flow (19) of a heating circuit (18) connected to the heater (1) is detected.

5. Method according to claim 1, wherein in step a) a temperature difference of a flow (19) and a return (20) of a heating circuit (18) connected to the heater (1) is detected.

6. Method according to one of the preceding claims, wherein the reference range is determined in step b) with the inclusion of operating data of the heater (1).

7. Method according to one of the preceding claims, wherein several parameters are recorded in step a).

8. Method according to one of the preceding claims, wherein in a step d) information about the result of the comparison according to step c) is provided or sent.

9. Computer program which, in conjunction with the regulation and control device (7) according to claim 11, is set up to carry out a method according to one of the preceding claims.

10. Machine-readable storage medium on which the computer program according to claim 9 is stored.

11. Regulating and control device (7) for a heating appliance (1), arranged for carrying out a method according to one of claims 1 to 8.

12. Heater (1), set up for the combustion of hydrogen, comprising a UV sensor (12), a temperature sensor (10) and a regulating and control device (7) according to claim 11.

13. Use of a temperature of a flame (11) of the heater (1) detected in or in the immediate vicinity of a combustion chamber (8) of a hydrogen-fuelled heater (1) for validating a signal of a first device for flame monitoring (12, 13), comprising a UV sensor (12), of the heater (1).