Measuring device for a heater, heater and method for detecting one or more flames

Abstract

The invention relates to a measuring device (23) for a heating device (10) having a combustion chamber (12) in which at least one flame (18) or several flames (18) can burn. It is proposed that at least one sensor (22) detecting the magnetic field (20, 92, 104) generated and / or influenced by the flame (18) or flames (18) and / or a detecting sensor device (24, 70) be provided. The invention also relates to a heating device (10) having such a measuring device (23). The invention also relates to a method for detecting one flame (18) or several flames (18), in particular using such a measuring device (23).

Description

Technical field

[0001] The present invention relates to a measuring device for a heater, a heater with such a measuring device and a method for detecting one or more flames using such a measuring device. State of the art

[0002] GB2599108A ​​describes a measuring device for detecting flames that detects the flame via its electromagnetic radiation in the ultraviolet range. Disclosure of the invention

[0003] The invention relates to a measuring device for a heater with a combustion chamber in which at least one flame or multiple flames can burn. It is characterized by the provision of at least one sensor and / or a detecting sensor device for detecting the magnetic field generated and / or influenced by the flame or flames. This eliminates the need for direct visual contact between the flame and the sensor. Such a measuring device is particularly suitable for detecting flames resulting from hydrogen combustion.

[0004] The features listed in the subclaims enable advantageous developments of the measuring device according to claim 1. It is advantageous if the at least one sensor or the sensor device is arranged near the flame.

[0005] If at least one sensor or the sensor device is arranged outside a housing that receives the flame or flames, a sensor or sensor device can be used that does not have to withstand the extreme conditions that prevail, for example, in the combustion chamber of a heating device.

[0006] The measurement accuracy can be increased if at least two sensors and / or sensor devices are arranged relative to the flame(s) in such a way that they can record the magnetic field at different positions, in particular with different orientations.

[0007] Effective filtering of the background noise can be achieved if at least one sensor or at least one sensor device is arranged close to the flame and if at least one sensor or sensor device is arranged at a distance from the flame(s).

[0008] An accurate measurement is achieved when a quantum magnetic field sensor is used as the sensor or sensor device. It is particularly advantageous if the quantum magnetic field sensor is both directionally and amplitude-sensitive.

[0009] To measure the flame or flames, it is advantageous if a magnetic field is superimposed on the flame or flames.

[0010] If a static and / or changing magnetic field is superimposed on the individual flame or multiple flames, additional information, such as amplitude or direction, can be extracted from the flame. In an advantageous embodiment, a permanent magnet and / or a coil is used to superimpose the magnetic field on the flame or flames.

[0011] The invention also relates to a heating device with a combustion chamber enclosing one or more flames and with a measuring device according to the invention.

[0012] The invention also relates to a method for detecting a flame or several flames, in particular with a measuring device according to the invention, which is characterized in that the magnetic field generated and / or influenced by the flame is detected with at least one sensor or sensor device, that the sensor or sensor device communicates with a control unit and that at least one signal carrying the status of the magnetic field is sent to the control unit.

[0013] The method can be improved if the flame's magnetic field is determined by at least two sensors in such a way that a different orientation is detected, and the signals are combined for amplification. In a simple case, such a combination corresponds to a modulo-based addition. However, processed signal components can also be combined to obtain a more interpretable result.

[0014] The method can be improved if a first sensor is used to determine a first signal for the magnetic field of the flame near the flame, if a second sensor is used to determine the magnetic field at a distance from the flame, and if the two measured values ​​are combined in such a way that interference components in the signal are at least partially eliminated. In the simplest case, this corresponds to a simple subtraction of the signals. Such "subtraction" should be understood to mean that the signals are combined in such a way that signal components that cannot be assigned to the magnetic field of the flame(s) are separated as far as possible from the signal that contains information about the magnetic field of the flame(s).

[0015] If a static and / or changing magnetic field is superimposed on the individual flame(s) or multiple flames in a process step, the influence of the individual flame(s) on this magnetic field can be used to determine further parameters influencing the flame(s). Such parameters can include, for example, flame intensity, a stoichiometric ratio of the combustion reactants, the combustion reactants themselves, etc.

[0016] If the sensor or sensor device is synchronized to a changing magnetic field in a process step, one or more parameters of a magnetic field induced in the flame by the changing magnetic field can be determined. Such parameters can include, for example, flame intensity, a stoichiometric ratio of the combustion reactants, the combustion reactants themselves, etc.

[0017] In a further process step, an induced magnetic field can be evaluated with regard to its orientation and amplitude.

[0018] Preferred embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. They show: Fig. 1 a schematic representation of a heater with a measuring device, Fig. 2 and Fig. 3 schematic representations of measuring devices with two sensors or with one sensor and one sensor device, Fig. 4 a schematic representation of a quantum magnetic field sensor, Fig. 5 to 7 schematic representations of measuring devices with two sensors or with one sensor and a sensor device superimposed by a magnetic field, Fig. 8 a measuring principle, Fig. 9 a process sequence for detecting one or more flames. Description of embodiments

[0019] In Fig. 1 shows a heater 10, schematically arranging a combustion chamber 12 and a control unit 14. Other components typically found in a heater, such as valves, pumps, or fans, are not shown. The combustion chamber 12 has a combustion chamber wall 16. A flame 18 is shown in the combustion chamber 12, which represents the flames typically generated by a burner in a combustion chamber 12 during operation of the heater 10.

[0020] It is also shown that the flame 18 is surrounded by a magnetic field 20. The invention is based on the finding that this magnetic field 20 is characteristic of the flame 18 and the fuel supplied for combustion. In the exemplary embodiment, hydrogen or a hydrogen / natural gas mixture is supplied as the fuel. However, the invention is preferably used in hydrogen combustion to detect the characteristic magnetic field 20 generated there.

[0021] A sensor 22 is arranged in the area of ​​the magnetic field 20, particularly near the flame 18. The sensor 22 is configured to be particularly sensitive to the magnetic field 20 generated by the flame 18. Magnetic sensors 20, such as fluxgate magnetometers, tunnel magnetoresistive sensors (TMR), GMR sensors, or quantum sensors, are particularly suitable for this purpose.

[0022] In the simplest case, a measuring device 23 according to the invention consists of a sensor that can communicate with a control unit 14. Typically, however, several sensors 22 or sensor devices 24 are part of the measuring device. Furthermore, the measuring device can also include components such as its own controller, an input and / or output device, its own power supply, or the like.

[0023] The sensor 22 is connected to the control unit 14 via a line 30. The sensor 22 communicates with the control unit 14 via this line 30. That is, it transmits the signals it has detected, either directly or in a processed form, to the control unit 14.

[0024] The control unit 14 processes the signals thus received and, if configured to do so, either controls the heater 10 and / or communicates with another control unit that assumes overall control of the heater 10 or a heating system. In particular, it can influence a burner (not shown here) and thus also the flame.

[0025] Instead of a simple sensor 22, a sensor device 24 can also be provided ( Fig. 3), which, in addition to a sensor element 26, which represents the active detection part of a sensor 22, also includes an operating or evaluation unit 28. The sensor device 24 then communicates with the control unit 14 via its operating or evaluation unit 28. Communication can take place either via a line 30 or via wireless communication. The position number 30 is also intended to represent a wireless connection or communication.

[0026] Since the sensor device 24 is equipped with an operating or evaluation unit 28, it is also possible for the communication to be bidirectional. Signals can be sent from the control unit 14 to the sensor device 24, which, for example, influence the sensitivity of the sensor device 24, initiate a reset, or contain similar control commands. This communication also makes it possible to check whether the control device 24 is functioning properly. Line 30 is designed to be bidirectional for this purpose.

[0027] The sensor 22 or the sensor device 24 can also be arranged outside the housing 32 of the combustion chamber 16. In Fig. In Figure 1, this is schematically illustrated by a partition wall 34 shown in dashed lines. This results in two possible arrangements. In a first embodiment, an area 36 in the combustion chamber 14 can actually be separated by the partition wall 34, which then accommodates the sensor 22 or the sensor device 24. The partition wall 34 must be designed to influence the magnetic field 20 as little as possible. The magnetic field 20 penetrates the partition wall 34 with little or no influence and acts on the sensor 22.

[0028] In a second embodiment, the sensor 22 or the sensor device 24 is arranged outside the combustion chamber 14. This has the advantage that the sensor 22 or the sensor device 24 can be easily serviced or replaced, possibly even during ongoing operation. Furthermore, the sensor 22 or the sensor device 24 can be subsequently installed in a heater 10.

[0029] As in Fig. 2, several sensors 22 and / or sensor devices 24 can also be arranged. In the embodiment according to Fig. 2, two sensors 22 are arranged relative to the flame 18 so that they detect the magnetic field at different positions. In the exemplary embodiment, they are located diametrically opposite the schematically illustrated flame 18. In a real embodiment, they can be arranged opposite each other, for example, on two long sides of a burner grate. Both sensors 22 or sensor devices 24 then communicate with the control unit 14, which in Fig. 2 is not shown.

[0030] In Fig. 3 shows that two sensors 22 and / or sensor devices 24 are arranged relative to the flame 18 such that they are located in the area of ​​the same orientation of the magnetic field 20. In the exemplary embodiment, the sensor 22 is arranged close to the flame 18, while the sensor device 24 is arranged farther away from the flame 18 relative to the sensor 22. It is clear to a person skilled in the art that the term "close to the flame 18" refers to a position that is so close to the flame 18 that the magnetic field 20 can be easily detected. This will usually be in a range between 1 cm and 20 cm from the flame center. The term "farther away" therefore refers to an area that is at a greater distance from the flame center than the closer sensor 22.

[0031] It is possible to use the examples according to Fig. 2 and Fig. 3, two sensors 22 or two sensor devices 24, or mixed forms thereof, are provided. If two sensors 22 and / or sensor devices 24 are provided, it is also possible to arrange one or both inside the combustion chamber 14 and the other or both outside the combustion chamber 14.

[0032] The embodiments according to the Fig. 2 and Fig. 3 can also be combined. This results in three sensors 22 and / or sensor devices 24 arranged accordingly. While such a configuration is more cost-intensive, it increases the accuracy and reliability of the measuring device 23.

[0033] In Fig. 9 shows the method sequence for detecting one or more flames 18. In a step 50, the magnetic field 20 generated by a flame 18 is detected by at least one sensor 20 or a sensor device 24. The sensor 22 or the sensor device 24 communicates with the control unit 14 and outputs at least one signal containing a status of the magnetic field 20 to the control unit 14 in a step 52. If multiple sensors 22 and / or sensor devices 24 are present, steps 50 and 52 are executed accordingly. In the Fig. Figure 9 shows the method for two sensors 22 or devices 24. Steps 50 and 52 are executed in parallel in the illustrated case. However, it is also possible for these steps 50 and 52 to be executed at different times depending on the sensor type.

[0034] A signal containing a status of the magnetic field 20 is understood to mean that the field strength and / or the orientation of the magnetic field 20 can be contained in the signal either point-by-point or in a time-resolved manner. The signal can be an analog signal or a digital signal. It can be transmitted serially or in parallel. It can be present continuously or in a time-resolved manner.

[0035] In the control unit 14, the signal is further processed in a step 54. Examples of this are given below. After the signal has been processed, an action can be performed in a step 56. Actions can include, for example, a display and / or a control and / or regulation of a fuel supply valve or even an emergency shutdown.

[0036] If in step 50 the magnetic field 20 is measured by means of two sensors 22 and / or sensor devices 24 according to the embodiment according to Fig. 2 and transmitted to the control unit 14 at section 52, the signals can be processed together. In order to amplify the signal, in step 54, when processing the signals from at least two sensors (22) and / or sensor devices (24), the magnetic field (22) of the flame (18) is determined in such a way that a different orientation is detected and the signal is combined for amplification. Depending on the magnetic field orientation, the signals can be added directly or must first be inverted in order to then be added with the other. In the simplest case, the signals are added in terms of their absolute values.

[0037] Also in the embodiment according to Fig. 3, in step 50, the magnetic field is detected by means of two sensors 22 and / or sensor devices 24 and transmitted to the control unit 14 in a step 52. The sensors 22 or sensor devices 24 are arranged such that one sensor 22 and / or sensor device 24 is arranged closer to the flame 18 and a second sensor 22 and / or sensor device 24 with the same magnetic field orientation is arranged further away from the flame 18. With this arrangement, the sensor 22 or sensor device 24 closest to the flame detects and detects a stronger magnetic field 20. The sensor 92 or sensor device 24 further away, on the other hand, is more likely to detect background noise or other interference signals that may be superimposed on the entire system. In step 54 of the processing, the signal containing the background noise or interference components is subtracted from the signal containing the magnetic field, so that a cleaned signal for the magnetic field 20 is obtained.This cleaned signal is then further processed and fed to the action in step 56. This represents a very simple case. Typically, the noise or interference components are removed.

[0038] If the embodiments of the Fig. 2 and Fig. 3 are combined, an amplified and cleaned signal can be obtained.

[0039] The measuring device and method according to the invention are particularly suitable for flames 18 generated by the combustion of hydrogen. An evaluation of a flame resulting from pure hydrogen combustion cannot be used for flame detection using an ion current measurement.

[0040] The types of magnetic field sensors that can be used for the measuring device, the heater, or the flame detection method have already been mentioned above. However, the invention is also based on the finding that quantum magnetic field sensors are particularly suitable. Here, too, various sensor types exist. A quantum magnetic field sensor, an NV sensor 70, was found. Although it is complex to operate, it can very sensitively detect various parameters from the magnetic field 20.

[0041] An NV sensor 70 features a negatively charged NV center in a diamond. NV stands for nitrogen vacancy. Advantages of this sensor principle include its very high sensitivity, the ability to determine the direction of the magnetic field (vector magnet geometry), a very large measuring range (> 1 Tesla), linearity through the use of the Zeeman effect, and the absence of degradation, since the measurement is based on quantum mechanical states.

[0042] In Fig. Figure 4 illustrates such an operating principle. To read a sensor based on an NV center, the magnetic resonance of the triplet's ground state is optically detected (ODMR, optically detected magnetic resonance). For this purpose, the NV center is excited with the green light of a corresponding laser 72. The laser beam 76 is guided onto the diamond 78 of the NV sensor 70 via an optics 74. The diamond 78 is exposed to a microwave 80 with a frequency of approximately 2.87 GHz. The microwave source and the corresponding piping are not explicitly shown.

[0043] The fluorescent light 82 transmitted by diamond 78 is passed through a color filter 84, which transmits only the red-shifted fluorescent light 86. This red-shifted fluorescent light 86 is focused onto a photodetector 90 via another optic 88. The red-shifted fluorescent light 86 exhibits a characteristic dip in the energy level of the electron spin resonance, which, due to the Zeeman effect, is linearly dependent on the magnetic field surrounding diamond 78. By absolutely measuring these Zeeman levels and their symmetric and asymmetric shifts, conclusions can be drawn about vector information, which includes an additional determination of the exact direction and thus additional information, which enables, for example, the differentiation of ions and thus the differentiation of fuels based on the different signal directions.For this purpose, a signal is transmitted from the photodetector 90 to an evaluation unit not shown here.

[0044] The described NV sensor 70 is thus an example of a sensor device 24 described above. In the following, the term “magnetic field sensor 22, 24, 70” is used for the optional use of a sensor 22, a sensor device 24 and / or an NV sensor 70.

[0045] In an embodiment according to the Fig. 5, a static magnetic field 92 is superimposed on the flame 18. Such a static magnetic field 92 can, as in the embodiment according to Fig. 5, are generated by means of a simple permanent magnet 94. The flame 18 distorts this static magnetic field 92 due to ionization during combustion and the resulting dialectical properties. A magnetic field sensor 22, 24, 70 placed close to the flame 18 determines the magnetic field 92 and detects a change or distortion in this static magnetic field 92 when the flame 18 is burning, i.e., when ions are present. From this distortion of the known static magnetic field 20, conclusions can then be drawn about the properties of the flame 18 or the fuels generating the flame 18.

[0046] Here, too, it is possible to increase the accuracy as already described by arranging multiple magnetic field sensors 22, 24, 70. Furthermore, especially when different magnetic field sensors 22, 24, 70 are used, it is possible to determine further parameters of the magnetic field 92, such as the relative permeability, which can then be used to draw conclusions about the fuel used or even defects in the combustion chamber 16. It is also possible to use such a measurement, particularly using an NV sensor 70, to determine the temperature of the flame 18.

[0047] Since quantum magnetic field sensors, such as the described NV sensor 70, are very sensitive, it is possible to use the earth's magnetic field 96 as the static magnetic field 92.

[0048] In Fig. 6 shows an arrangement of several magnetic field sensors 22, 24, 70 that surround a flame 18 in a circle. In this embodiment, the earth's magnetic field 96 is superimposed on the flame 18 and is detected by these magnetic field sensors 20, 24, 70.

[0049] In Fig. Figure 7 shows three variants of how a static magnetic field 92 can be influenced by the flame 18. Permanent magnets 94 are arranged such that the north-south axis of the permanent magnet 94 runs along the flame propagation of the flame 18.

[0050] In illustration a), a large flame 18 is shown, while in illustration b), a smaller flame 18 is shown. The static magnetic field 92 is also influenced differently at different locations due to flame turbulence. This change over time can be detected and evaluated. In illustration c), a different fuel is used than in illustrations a) and b), which generates different ions in the flame 18. These different ions influence the static magnetic field 92 in a different way than the flame 18 in illustrations a) and b). By measuring the influence of the static magnetic field 92, conclusions can be drawn about the fuel generating these ions. Even if only one magnetic field sensor 22, 24, 70 is shown here, it is also possible to use several such magnetic field sensors 22, 24, 70.

[0051] A further embodiment of the invention is shown in Fig. 8. There, a coil 98 is shown, the axial orientation of which defines an axis 100 pointing toward the flame 18. The coil 98 is connected to a generator 102, which can supply the coil 98 with a direct current and / or an alternating current. As a result, the coil 98 generates a static and / or dynamic magnetic field 104.

[0052] If only a static magnetic field 104 is generated via the coil 98, a detection of the flame 18 can be carried out analogously to the embodiment of the Fig. 4 to 6.

[0053] In the embodiment according to Fig. 8, a magnetic field sensor 20, 24, 70 is arranged such that its detection range lies on the axis 100. The magnetic field sensor 20, 24, 70 is connected to a signal processing unit 106, to which it can transmit a signal and from which it can also receive a signal. The signal processing unit 106 is also connected to the generator 102 and can receive its signal or output signals to the generator 102.

[0054] In the exemplary embodiment, the flame 18 is located between the coil 98 and the magnetic field sensor 20, 24, 70.

[0055] When coil 98 is supplied with a direct current, it generates a static magnetic field 104 directed toward flame 18 and sensor 22, 24, or 70. The ions moving in flame 18 are forced into drifts or even circular orbits by magnetic field 104. The size of the drifts or circular orbits, the speed of the ions in the drifts or circular orbits, and the intensity in the drifts or circular orbits are largely determined by magnetic field 104 and the ions present in the plasma of flame 18.

[0056] The ions moving along the circular paths generate a counter field 108, which can be evaluated by the magnetic field sensor 20, 24, 70. The NV sensor 70 is particularly well suited for this purpose. The evaluation of this counter field 108 in terms of amplitude, frequency, and direction then allows conclusions to be drawn about the flame 18, its size, stability, temperature, as well as the ions and thus the combustion products used.

[0057] The opposing field 108 also arises in the embodiments according to the Fig. 5 to 7, since there, too, the ions of flame 18 are excited to such drifts or circular orbits. However, this is not explicitly described there. The opposing field 108 is to be considered a field generated by flame 18.

[0058] The coil 98 is also suitable for generating a dynamic magnetic field 104, which then acts on the flame 18. In a first measurement or detection, a frequency and an amplitude for the magnetic field 104 are set, for which optimal detection of the opposing field 108 generated by the flame 18 is possible using the sensor type of the magnetic field sensor 20, 24, 70 used.

[0059] In another or further measurement or detection, the magnetic field sensor 20, 24, 70, in particular the NV sensor 70, is adjusted to the frequency of the alternating magnetic field 104. The measurement is performed in a so-called lock-in detection. Thus, only the opposing field 108 specifically generated at this frequency is evaluated. The field strengths of the opposing field 108 are in the range of less than 100 mT.

[0060] In another or further measurement or detection, the frequency of the opposing field 108 is varied, in particular, from an initial value to a final value. By sweeping through the frequencies in this way, spectroscopy can be performed on the plasma of the flame 18, allowing the ion composition and thus the combustion mixture to be analyzed and optimally adjusted via a feedback channel. This measurement can be performed openly or in the aforementioned lock-in detection.

[0061] Even in the embodiments with a single coil 98, it is possible, as already described above, to use multiple magnetic field sensors 20, 24, 70 to achieve signal amplification or improve the signal-to-noise ratio. It is also possible to use multiple coils 98, which are then arranged opposite one another or offset from one another.

[0062] The measurements or detections at flame 18 can be performed and evaluated absolutely. The results can then be analyzed according to physical or chemical principles, and conclusions drawn from them.

[0063] However, empirical tests are preferably conducted in the laboratory and the results are stored in a memory or in the cloud. The results measured or detected in the field can then be compared with this stored data, and conclusions can be drawn from them. These conclusions can then be used to indicate events, implement control or regulation measures, or even forward events to monitoring centers.

[0064] All data can also be simulated using model calculations or intrapolated or extrapolated based on empirically measured data. These results are also documented and can be stored in a memory.

[0065] If many such data sets already exist, it is possible to obtain and document the results using machine e-learning. This typically involves using a neural network of a computer-aided learning system. Data sets generated in real time in the laboratory or in the field under different conditions are input as input data. The result determined by the computer-aided learning system is compared with the true result and subjected to recursion. Once an acceptable degree of true results has been determined, the thus-trained neural network can be implemented in the control unit 14 and used.

[0066] The quality of the trained neural network can be continuously checked or optimized using the states found during operation. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] GB 2599108A ​​

[0002]

Claims

[1] Measuring device (23) for a heating device (10) with a combustion chamber (12) in which at least one flame (18) can burn or several flames (18) can burn, characterized by that at least one sensor (22) detecting the magnetic field (20, 92, 104) generated and / or influenced by the flame (18) or the flames (18) and / or a detecting sensor device (24, 70) is provided. [2] Measuring device (23) according to one of the preceding claims, characterized by that at least two sensors (22) and / or sensor devices (24, 70) are arranged relative to the flame (18) or the flames (18) in such a way that they can record the magnetic field (20, 92, 104) at different positions, in particular with different orientations. [3] Measuring device (23) according to one of the preceding claims, characterized bythat at least one sensor (22) or at least one sensor device (24, 70) is arranged near the flame and that at least one sensor (22) or one sensor device (24, 70) is arranged at a distance from the flame (18) or the flames (18). [4] Measuring device (23) according to one of the preceding claims, characterized by that the sensor (22) or the sensor device (24, 70) is or has a quantum magnetic field sensor. [5] Measuring device (23) according to one of the preceding claims, characterized by that a magnetic field (92, 96, 104) is superimposed on the at least one flame (18) or the plurality of flames (18). [6] Measuring device (23) according to one of the preceding claims, characterized by that the magnetic field (92, 96, 104) is a static and / or a changing field. [7] Measuring device (23) according to one of the preceding claims, characterized bythat a permanent magnet (94) and / or a coil (98) is arranged in the vicinity of the one flame (18) or the plurality of flames (18). [8] Heating device (10) with a combustion chamber (12) enclosing one or more flames (18) and with a measuring device (23) according to one of the preceding claims. [9] Method for detecting a flame (18) or several flames (18), in particular with a measuring device (23) according to one of claims 1 to 7, characterized by that the magnetic field (20, 92, 96, 104) generated and / or influenced by the flame (18) is detected by at least one sensor (22) or one sensor device (24, 70), that the sensor (22) or the sensor device (24, 70) communicates with a control unit (14) and that at least one signal carrying a status of the magnetic field (20, 92, 96, 104) is sent to the control unit (14). [10] Method for detecting one or more flames (18) according to claim 9, characterized by that the magnetic field (22, 104) of the flame (18) and / or the magnetic field 92, 96 influenced by the flame (18) is determined by at least two sensors (22) and / or sensor devices (24, 70) in such a way that a different orientation is detected and that the signal is combined for amplification. [11] Method for detecting one or more flames (18) according to one of claims 9 or 10, characterized bythat a first signal for the magnetic field (20, 104) of the flame (18) in the vicinity of the flame is determined by means of a first sensor (22) and / or a sensor device (24, 70), that the magnetic field (20) from the flame (18) and / or the magnetic field (92, 96) influenced by the flame (18) is determined at a distance by means of a second sensor (22) and / or a sensor device (24), and that the two measured values ​​are combined in such a way that interference components in the signal are at least partially eliminated. [12] Method for detecting a flame (18) or several flames (18) according to one of claims 9 to 11, characterized by that a static and / or changing magnetic field (92, 96, 104) is applied to the flame and that the influence of the flame (18) on this magnetic field (92, 96, 104) is determined. [13] Method for detecting a flame (18) or several flames (18) according to one of claims 9 to 12, characterized bythat the sensor (22) or the sensor device (24, 70) is synchronized to a or the changing magnetic field (92, 96, 104) and an induced magnetic field (108) is determined. [14] Method for detecting one or more flames (18) according to claim 13, characterized by that the induced magnetic field (108) is evaluated with regard to its orientation and its amplitude.

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