Heating device, method for operating a heating device, computer program and machine-readable storage medium

Abstract

The invention relates to a heating device (100) with a heating power (L) that is variable within a power modulation range, wherein the power modulation range includes values ​​from a predefinable minimum power (L). MIN ) up to a rated power (L MAXThe method comprises the steps of providing a burner (200) for generating the heating power (L) by burning a fuel-air mixture flow (AB) while producing at least one flame (F), and providing an optical monitoring device (300) for generating a measured value (M) corresponding to the optical radiation (S) of the flame (F). During heating operation of the heating device (100), the measured value (M) of the optical monitoring device (300) is compared with a limit value (G) in a first comparison, in particular by means of a control device (400), and the presence of a flame (F) is determined based on the result of this first comparison. It is proposed to define a value for the minimum power (L). MIN ), in particular by means of the control unit (400), to adjust if no flame (F) is detected in the heating operation or if the measured value (M) is detected to be in a tolerance range just above the limit value (G).

Description

State of the art

[0001] Heating devices with variable heating output within a power modulation range, as well as methods for operating them, are known from the prior art. The power modulation range includes values ​​from a predefinable minimum output to a nominal output. These heating devices comprise a burner for combusting a fuel-air mixture and an optical monitoring device for generating a measured value corresponding to the optical radiation of a combustion flame. A control unit detects whether a flame is present.

[0002] The object of the invention is to provide an improved heating device and an improved method for operating it. Disclosure of the invention

[0003] The invention relates to a method for operating a heating device with a variable heating output within a power modulation range, wherein the power modulation range comprises values ​​from a predefinable minimum output up to a nominal output. The method includes the steps of providing a burner for generating the heating output by burning a fuel-air mixture flow, in particular a variable-rate mixture containing hydrogen, producing at least one flame, and providing an optical monitoring device for generating a measured value corresponding to the optical radiation of the flame. During heating operation of the device, the measured value of the optical monitoring device is compared with a limit value in a first comparison, in particular by means of a control device, and based on the result of this first comparison, it is determined whether a flame is present.

[0004] It is proposed that, in an adjustment step, a minimum power value be adjusted, in particular by means of the control device, if no flame is detected during heating operation or if the measured value is detected to be in a tolerance range just above the limit value.

[0005] The design according to the invention allows, in particular, the reliable formation and / or detection of a flame. Specifically, it ensures that the heating output of the heating device does not extend to points where the measured value is below the limit value and the burner would shut off. Reliable operation of the heating device is thus guaranteed. The availability of the heating device for heating purposes is increased. Restrictions on heating operation due to the absence of a measured value, especially one of the expected or required magnitude, are avoided.

[0006] In this context, a heating device is understood to mean, in particular, a device installed, for example, in a building, for generating heat and / or for heating a useful fluid such as water, heating water, or air, for example, for space heating and / or domestic hot water production. Specifically, this refers to a fuel-fired heating device, in particular one fired with hydrogen-containing fuel. Heating output is understood here to mean, in particular, the thermal output generated or that can be generated by the heating device through the combustion of a fuel-air mixture flow, producing a flame. Output is understood here to mean, in particular, a value of the power output.

[0007] In this context, a power modulation range refers specifically to a range of heating output within which the heating device can operate safely and without undesirable failures. The heating output can be varied, for example, depending on a heat demand, from a minimum output to a nominal output (maximum output), particularly continuously or in stages, especially by means of a control device. The minimum output is the lower limit and the nominal output is the upper limit of the power modulation range.

[0008] A minimum power output value and / or a nominal power output value can be predefined and / or predefined, in particular stored and / or storable, in a control unit and / or a storage module of a heating device. In particular, a minimum power output value and / or a nominal power output value can be predefined and / or predefined, in particular stored and / or storable, based on a minimum and / or maximum delivery rate of an air conveying device. An initial minimum power output, in particular specified by the manufacturer of the heating device for a new condition, can, for example, be in the range of 10% to 30% of the nominal power output.

[0009] For the purposes of this text, a burner is understood to be a combustion device designed to convey, meter, combine, and mix a fuel and air stream, to convey this mixture, and to supply it to a combustion chamber, ignite it, and combust it. The burner may comprise various components, such as an air supply unit (also called a blower, fan, or ventilator), a fuel valve assembly, a mixing unit, a mixture distribution unit, an ignition unit, a flame-holding unit, and / or a burner surface. The fuel valve assembly includes, in particular, at least one fuel valve that can be opened to release and meter the fuel.In this context, a flame is understood to mean in particular a spatial area of ​​an exothermic combustion of the fuel-air mixture flow, whereby the flame emits electromagnetic or optical radiation in the visible, ultraviolet and / or infrared spectral range.

[0010] In this context, an optical monitoring device is understood to mean, in particular, a flame monitoring device capable of detecting the presence of a flame and / or the quality of combustion. The optical monitoring device specifically comprises an optical flame sensor that detects the flame's radiation and converts it into a corresponding electrical measurement. The flame sensor can be designed as a flame monitor, detecting only the presence or absence of a flame. Alternatively, the flame sensor can also be used for combustion control, particularly for air-fuel ratio control. The measurement can correspond to, in particular, the brightness, intensity, color, color distribution, size, and / or energy output of the flame. The measurement is transmitted, in particular, as an electrical signal, with the measurement being encoded within that signal.The optical flame sensor operates, in particular, without contact and can be positioned at a distance from the flame. Specifically, the flame sensor can be located outside a combustion chamber or combustion chamber that receives the flame. In this case, the optical monitoring device can, in particular, include a sight glass (protective glass) that allows radiation to flow between the flame and the flame sensor. The sight glass can, in particular, be arranged in an opening (window opening) formed in a combustion chamber wall. The sight glass can, in particular, be at least partially transparent, and in particular fully transparent, to the optical flame radiation.

[0011] In this context, "heating operation" refers specifically to the operation of the heating device to initiate and / or carry out heat generation, particularly to meet a heat demand. "To initiate and / or carry out" refers specifically to a currently existing intention, including the correspondingly executed process steps. This does not, in particular, imply any statement regarding the success of the intention and / or the process steps, especially concerning flame formation. "Initiating heat generation" refers specifically to burner start-up operation, including supplying an airflow, releasing ignition energy or voltage to the ignition device, opening the fuel valve during an ignition safety period, metering the fuel flow by means of the fuel valve device, and supplying the fuel-air mixture to the burner surface.The burner start-up process ends when the ignition safety time expires. If no flame is detected by the end of the burner start-up process, the burner start is unsuccessful, the burner start and heating operation are aborted, and the fuel valve is closed. If a flame is detected by the end of the burner start-up process, the burner start is successful, and the fuel valve can remain open.

[0012] The term "heat generation following a successful burner start" here refers specifically to combustion operation, particularly continuous combustion, with flame formation while the fuel valve remains open. Heating operation is specifically characterized, and defined, by an intentionally opened fuel valve to release fuel for ignition and / or combustion. A flame may be detectable during heating operation. However, under certain unfavorable operating conditions, a flame may not be detectable at all times. If a flame is detected, combustion continues to meet the heat demand. If, particularly during combustion operation, no flame is detected, heating operation is terminated; specifically, the fuel valve is closed and / or held closed.If heat demand persists, a new heating operation may follow after the shutdown to initiate and / or carry out heat generation. The invention remedies this and ensures the formation of a flame that burns reliably and / or is detected.

[0013] In this context, a control unit is understood to be, in particular, an electrical and / or electronic device for controlling and / or regulating the heating system, especially in relation to a heat demand. The control unit can, in particular, communicate with and control the burner, the air supply system, the fuel valve system, the ignition system, and / or the optical monitoring device, read actual values ​​from them, and / or output setpoint values ​​and / or electrical power to them. In this context, a limit value is understood to be, in particular, a predefined reference value for evaluating the measured value of the optical monitoring device and for detecting the presence or absence of a flame (flame detection). Specifically, the limit value represents a minimum value for evaluating the measured value, which is considered reliable in detecting the presence of a flame.The limit value is stored in the control unit and / or a memory module. If the measured value is greater than or equal to the limit value, a flame is considered detected and the burner can continue operating. If the measured value is less than the limit value, a flame is considered not detected and the burner is switched off; specifically, the fuel valve is closed and the fuel flow to the burner is stopped.

[0014] The heating device may only be operated in combustion mode if a flame is present. The flame is detected by the optical monitoring device, which translates the optical flame radiation into an electrical measurement. A flame must be detected no later than the end of the burner start-up phase to operate the heating device in combustion mode. If no flame is detected, the burner shuts down, specifically the fuel valve closes. There can be various reasons for a failure to register a measurement from the optical monitoring device, particularly one of the expected magnitude, and / or for the measurement falling below a threshold value. For example, if the optical monitoring device becomes dirty, the flame radiation may be attenuated before reaching the optical flame sensor, thus reducing the measurement and preventing reliable detection of the flame.Aging of the optical monitoring device, particularly the flame sensor, can also lead to a reduction in the measured value. Furthermore, the absence of a measured value can also be due to a lack of flame ignition, an insufficiently strong flame, and / or an excessively lean fuel-air mixture.

[0015] Adjusting the minimum power value here refers specifically to changing the value of the minimum power. Specifically, adjusting the minimum power value means increasing the value of the minimum power. In particular, the minimum power is set to a value at which a flame is produced that can be reliably detected.

[0016] The adjustment, in particular the increase, of the minimum performance can be done in one step or in repeated steps (for example, iteration steps).

[0017] A tolerance range slightly above the limit value is understood here to mean, in particular, a range of values ​​starting at the limit value and extending, for example, to 1.1 to 2 times the limit value. A flame that produces a measured value in the optical monitoring device within a tolerance range slightly above the limit value is a weak flame.

[0018] In a preferred embodiment, the minimum power output is increased, particularly by means of the control unit. Specifically, the minimum power output is increased by 2% to 10%, preferably by 5%, relative to the rated power output. Alternatively, the minimum power output is increased by 10% to 50%, preferably by 25%, relative to the current minimum power output. The minimum power output is increased at most to the rated power output. Therefore, the heating output does not exceed the rated power output.

[0019] Increasing the minimum power setting limits the power modulation range to higher heating power levels. Low and / or very low heating power levels are no longer reached. As a result, the potentially generated flames are larger and more intense, emitting more optical flame radiation. The optical monitoring device registers a larger reading, which is more likely to exceed the limit, and the flame is detected more reliably. This ensures more reliable operation of the heating device and increases its availability for heating purposes.

[0020] This is particularly useful when no flame is detected. This ensures that the heating output of the heating device is not further reduced during subsequent heating cycles, which could result in the measured value falling below the limit and the burner shutting off.

[0021] In a further preferred embodiment, the value of the minimum power is set to the current value of the heating power, in particular by means of the control device.

[0022] This is particularly useful when a flame is detected whose measured value is just above the limit value within a tolerance range. This ensures that the heating output of the device is not further reduced, which could lead to points where the measured value is lower than the limit value and the burner would shut off. This guarantees more reliable operation of the heating device and increases its availability for heating purposes.

[0023] In a further preferred embodiment, the value of the minimum power is adjusted, in particular by means of the control device, and in particular increased, until a currently measured measured value is greater than or equal to the limit value.

[0024] The adjustment, particularly the increase, of the minimum power output can be performed in one step or in repeated steps (e.g., iterations) until the current measured value exceeds the limit. This can then be continued in one step or in several iterations until the current measured value is above the tolerance range just above the limit, i.e., until the current measured value is greater than or equal to the upper tolerance value of that range. This ensures more reliable operation of the heating device and increases its availability for heating purposes.

[0025] In a further preferred embodiment, the adjusted value of the minimum power is stored in a memory module, in particular by means of the control unit.

[0026] The memory module and / or any additional memory module constitutes a data storage device, specifically a read / write memory module, RAM data storage, and / or non-volatile data storage. Specifically, during saving, a previous minimum performance value is overwritten with the adjusted minimum performance value. Specifically, the memory module and / or any additional memory module is included in the control unit. Specifically, the control unit and the memory module exchange information.

[0027] In a further preferred embodiment, the adjusted and / or stored minimum output value, in particular by means of the control unit, is used as the basis for a current heating operation. Alternatively, the adjusted and / or stored minimum output value is used as the basis for a subsequent heating operation, in particular starting with a subsequent burner start.

[0028] In another preferred embodiment, an initial warning message is issued, in particular by means of the control unit, when the control unit adjusts the value of the minimum power.

[0029] In a further preferred embodiment, a second warning message is issued, in particular by means of the control device, if the adjusted value of the minimum power exceeds a predefinable threshold, in particular 50% of the rated power.

[0030] To issue the first and / or second warning message, the heating device and / or the control unit includes at least one output or display device that can be controlled by the control unit. The output or display device can be based on optical or acoustic information transmission. The warning messages can include information such as "The optical monitoring device is dirty" or "The heating device's performance range is limited."

[0031] Another preferred configuration includes the following steps • Providing a, in particular an additional, storage module with expected values ​​stored therein for measured values ​​generated at predefinable, in particular predetermined, operating points of the heating device, • Generating measured values ​​at at least one of the predefinable operating points, preferably at several or all operating points, using the optical monitoring device, • Recognizing, in a second comparison, deviations between the expected values ​​and the corresponding measured values, • Based on the deviations, diagnose and / or identify a cause for the deviations.

[0032] The term "predefinable or specified operating points" for the heating device refers specifically to operating points with different heating outputs within the power modulation range. For example, each operating point could be at one-tenth or multiples of one-tenth of the nominal output (i.e., at 10%, 20%, 30%, and so on up to 100% of the nominal output). An expected value, in this context, refers specifically to a measured value of the optical flame radiation that can be expected under ideal operating and / or device conditions. These expected values ​​may be specified, particularly by the manufacturer of the heating device. Alternatively, the expected values ​​may be based on measured values ​​generated when the heating device was new. The measured values ​​generated at at least one operating point can be generated, in particular, during heating operation when the heating output corresponds to one of the operating points.A deviation is determined primarily as a difference value. Alternatively, the deviation can also be determined as a ratio value. Based on the deviations between the measured values ​​and the corresponding expected values, the cause of the deviations can be deduced. The cause is communicated via a message, particularly on an output device or display. Furthermore, the control unit can intervene in the operation of the heating device in response to the identified cause of the deviations; for example, the control unit can disable the heating device from further operation.

[0033] For example, percentage deviations of the same or similar magnitude at different operating points may indicate contamination or aging of the optical monitoring device. Deviations at only one or a few operating points point to a different cause. A time-dependent analysis of the measured values ​​and / or deviations can also be used for diagnosis.

[0034] In a further preferred embodiment, a predefinable burner start-up power value is increased, particularly by means of the control device, if the value of the adjusted minimum power is greater than a previously or originally predefinable burner start-up power value, particularly one specified by the manufacturer. Specifically, the burner start-up power value is increased to the value of the adjusted minimum power or to a higher value.

[0035] The term "burner start-up power" here refers specifically to a predetermined and / or predeterminable heating output at burner start-up. The burner start-up power can, for example, be in the range of 30% to 50% of the nominal output.

[0036] In a further preferred embodiment, the value of the minimum power is adjusted, in particular by means of the control device, especially reduced and / or reset to a previously or originally specified minimum power value, in particular by the manufacturer, preferably when maintenance of the heating device and / or the optical monitoring device has been detected.

[0037] Maintenance here refers in particular to replacement, repair and / or cleaning.

[0038] Alternatively, the control unit adjusts the minimum power value, lowers the value and / or resets the value to a previously or originally specified minimum power value if a measured value significantly greater than the limit is measured at the point of a current minimum power.

[0039] Alternatively, the control unit adjusts the minimum power value, reduces the value and / or resets the value to a previously or originally specified minimum power value after a predefinable operating time of the heating device, particularly in combustion operation, for example after 100 to 500 operating hours.

[0040] This ensures that a restricted power modulation range is reset to an original wide power modulation range when the cause of flame failure or a weak flame has been eliminated.

[0041] In a further preferred embodiment of the invention, the heating device, the burner, and the method for operating the heating device are configured to safely combust a fuel containing at least 50% molecular hydrogen by volume. For this purpose, the burner comprises all necessary components designed for the passage, metering, ignition, and / or combustion of the hydrogen-containing fuel, for example, appropriately configured: fuel valve assembly, mixing device, mixture distribution device, ignition device, flame holding device, burner surface, and / or optical monitoring device. The method comprises all necessary process steps and parameters suitable for the passage, metering, ignition, and / or combustion of the hydrogen-containing fuel, for example, appropriately configured: ignition reliability time, ignition energy, ignition voltage, fuel metering, and flame detection threshold.

[0042] In this context, "fuel" refers specifically to a gaseous fuel. "Hydrogen" refers specifically to molecular hydrogen (H₂). For example, the fuel containing hydrogen, or the hydrogen-containing fuel, can consist of approximately 10% by volume (corresponding to an admixture to another fuel gas), preferably more than 50% by volume, and particularly preferably more than 90% by volume (corresponding to hydrogen produced with reasonable economic effort).

[0043] The invention further relates to a computer program which is configured to perform all steps of the method described above.

[0044] The invention further relates to a machine-readable storage medium on which the computer program is stored. The storage medium comprises, in particular, the memory module and / or the further memory module.

[0045] The invention further relates to a heating device with a variable heating output within a power modulation range, wherein the power modulation range comprises values ​​from a predefinable minimum output up to a nominal output. The heating device includes a burner for generating the heating output by burning a fuel-air mixture flow, producing at least one flame, an optical monitoring device for generating a measured value corresponding to the optical radiation of the flame, and a control device configured for comparing, during heating operation of the heating device, in a first comparison, the measured value with a limit value and detecting, based on the result of the first comparison, whether a flame is present.

[0046] It is proposed that the heating device, in particular the control device of the heating device, be equipped to adjust a minimum power value by a method, in particular by one of the methods described above, if the control device does not detect a flame in heating operation or detects the measured value in a tolerance range just above the limit value. drawing

[0047] Further embodiments and advantages will become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. It is advantageous for those skilled in the art to also consider the features individually and combine them into meaningful further combinations. The drawings schematically show: Fig. 1 a heating device, Fig. 2 a first characteristic map of measured values ​​from the optical monitoring device versus the heating power, Fig. 3 a second characteristic map of measured values ​​from the optical monitoring device versus the heating power.

[0048] Fig. Figure 1 shows a heating device 100 according to the invention, for example installed in a building, which can vary its heating power L within a power modulation range, wherein the power modulation range includes values ​​from a predefinable minimum power L MIN up to a rated power L MAX exhibits.

[0049] The heating device 100 comprises a burner 200, which is configured to generate the heating output L by burning a fuel-air mixture AB, thereby producing at least one flame F. The burner 200 is connected to an air source 10, for example, the outside environment 10 of the building, and a fuel source 20. An air supply device 202 supplies a variable-volume air flow A. A fuel valve device 204 meters a fuel flow B according to the quantity of the air flow A. In a mixing device 206, air flow A and fuel flow B are combined and mixed to form the fuel-air mixture AB. The mixture AB is fed to a burner surface 208 and discharged into a combustion chamber 110. The combustion chamber 110 is formed here within a combustion chamber 120.In the combustion chamber 110, at the burner surface 208, the mixture flow AB is ignited by means of an ignition device (not shown here), and flames F of combustion are formed, releasing the heating power L as thermal output. The heating power L is transferred via a heat exchanger 130 to a heating fluid such as heating water and / or to a service fluid such as drinking water (not shown here). Exhaust gases C produced during combustion are discharged into an external environment 10.

[0050] The heating device 100 further comprises an optical monitoring device 300, which can detect the presence of the flame F and / or the quality of combustion. The optical monitoring device 300 includes an optical flame sensor 302, which is configured to generate a measured value M corresponding to the optical flame radiation S (dashed line) of the flame F. The flame sensor 302 is arranged so that it has a line of sight to at least a partial area of ​​the combustion chamber 110 and / or the flame F. The optical monitoring device 300 may further include a sight glass 304, which is arranged in a wall of the combustion chamber 120 and allows visual contact between the flame F and the flame sensor 302. The sight glass 304 is at least partially transparent, and in particular fully transparent, to the optical flame radiation S to be detected by the flame sensor 302.

[0051] The heating device 100 comprises a control unit 400, which is configured to compare the measured value M of the optical monitoring device 300 with a limit value G in a first comparison during heating operation of the heating device 100, and to recognize, based on a result of the first comparison, whether a flame F, in particular a sufficiently large or strong flame F, is present.

[0052] The control unit 400 can also control and / or regulate the air conveying unit 202 and the fuel valve unit 204.

[0053] The heating device 100, in particular the control unit 400, is designed to set a minimum power value L MIN to adjust if the control unit 400 does not detect a flame F in heating mode or detects a measured value M that is within a tolerance range just above the limit value G.

[0054] Possible reasons why the control unit 400 does not detect a flame F during heating operation are: There is no flame F. Or a flame F exists, but it is so weak or small that the measured value M is less than the limit value G. And / or the optical monitoring device 300 is faulty. In particular, the flame sensor 302 may be defective and not generate a measured value M despite flame radiation S. Or the flame sensor 302 may be aged, so that the measured value M of any flame radiation S present is less than the limit value G. Or the sight glass 304 may be dirty, so that any flame radiation S present does not reach the flame sensor 302, or only reaches it in a dimmed form, and the measured value M is less than the limit value G.

[0055] The burner 200 is designed to safely combust a fuel stream B containing at least 50% hydrogen by volume. This means, for example, that the fuel valve assembly 204, the burner surface 208, the ignition device (not shown here), and the optical monitoring device 300 are designed to meter the hydrogen-containing fuel stream B, ignite and combust the hydrogen-containing fuel-air mixture AB, maintain the flames F on the burner surface 208, detect the flame radiation S, and generate corresponding measured values ​​M.

[0056] Fig. Figure 2 shows a first characteristic map of measured values ​​M of the optical monitoring device 300 versus the heating power L. The power modulation range of the heating device 100 can range from a minimum power L MIN up to a rated power L MAX(“100%”) vary. A burner start, i.e., the ignition of a fuel-air mixture flow AB after a combustion pause, occurs at a burner start power L. ST .

[0057] A flame F is considered detected when, during heating operation, a measured value M of the optical monitoring device 300 is greater than or equal to a limit value G. Smaller measured values ​​M lead to the burner 200 being switched off, i.e., the fuel supply B being stopped and any flames F being extinguished.

[0058] M0(L) shows a curve of measured values ​​M as they can be set depending on the heating output L under ideal operating and / or device conditions of the heating device 100, for example, in a new state or in a serviced or adjusted state of the heating device 100. M0(L) is shown here as a straight line. The course of M0(L) can also take on other shapes and / or values ​​M, for example, depending on the burner design.

[0059] M1(L) shows a curve of measured values ​​M as they can be set depending on the heating power L under real operating and / or device conditions of the heating device 100, for example in a deteriorated, aged, dirty or misaligned state of the heating device 100 compared to the ideal operating and / or device conditions.

[0060] M1(L) is represented here as a straight line. The curve of M1(L) can also take on other shapes and / or values ​​M, depending, for example, on the actual operating and / or device conditions or the burner design.

[0061] Fig. Figure 3 shows a second characteristic map of measured values ​​M of the optical monitoring device 300 versus the heating power L, in particular a section of the first characteristic map of Fig. 2.

[0062] It can be seen that the measured values ​​M0(L) measured under ideal operating and / or device conditions are consistent across the entire power modulation range L MIN,0 to L MAX are greater than or equal to the limit value G. In other words, under ideal operating and / or device conditions, heating outputs L are greater than or equal to the minimum output L. MIN,0 A flame F is detected because the measured value M is greater than or equal to the limit value G.

[0063] Below minimum power L MIN,0 In particular, the minimum power value L that applies under ideal operating and / or device conditions, for example, a value specified by the manufacturer for the new state of the heating device 100, should be used here. MIN,0 be understood.

[0064] It can be seen that the measured values ​​M1(L) under real operating and / or device conditions are smaller than the measured values ​​M0(L). This results from the real operating and / or device conditions being worse than ideal operating and / or device conditions, thus generating smaller measured values ​​M1(L).

[0065] It can also be seen that under real operating and / or device conditions, the heating outputs L are equal to or slightly greater than the minimum output L. MIN,0 The measured values ​​M1(L) generated are smaller than the limit value G – unlike the M0(L) generated under ideal operating and / or device conditions. In other words, under real operating and / or device conditions, at heating powers L equal to or slightly greater than the minimum power L, the measured values ​​M0(L) are lower than the limit value G. MIN,0No flame F detected because the measured value M1(L) is less than the limit value G. The burner 200 switches off and cannot meet a heat demand.

[0066] The invention takes effect here to prevent the heating device 100 from entering the portion of the power modulation range in which, under real operating and / or device conditions, no flame F is detected and the burner 200 shuts off. The invention is – as described in the Fig. 3. Example shown - characterized in that a value of the minimum power L MIN The value is adjusted if no flame F is detected during heating operation. MIN This is done in one, especially first, adjustment step of L MIN,0 on L MIN,1 adapted, in particular increased (see left hatched arrow).

[0067] Below minimum power L MIN,1In particular, the minimum power value L should be an adapted, especially increased, value applicable under real operating and / or device conditions. MIN be understood.

[0068] If, during heating operation with the minimum output already adjusted L MIN,1 If, again, no flame F is detected and the burner 200 switches off, the minimum output can be further adjusted, in particular increased, in a further adjustment step. For example, the minimum output L can be MIN in a second adjustment step of L MIN,1 on L MIN,2 They will be adjusted, in particular increased (see right hatched arrow).

[0069] Below minimum power L MIN,2 In particular, an adjusted, especially increased, value of the minimum power L is to be used here, applicable under further deteriorated real operating and / or device conditions. MIN be understood.

[0070] The effect of increasing the minimum power L MIN The fact is that in heating operation such heating outputs L, for example in the range L MIN,0 to L MIN,1 or L MIN,0 to L MIN,2 , where no flame F is detected due to insufficient measured value M, are omitted, and the power modulation range is reduced to a smaller power modulation range L MIN,1 to L MAX or L MIN,2 to L MAX The power modulation range is limited. Within this limited range, the flame F burns stably and is reliably detected. There are no unwanted interruptions in heating operation.

[0071] Based on warning messages, a user or installer of the heating device 100 can recognize that the power modulation range has been restricted and, for example, perform maintenance, cleaning, or component replacement (sight glass 304 or flame sensor 302). In a subsequent heating operation, the heating device 100 recognizes the restored ideal operating and / or device conditions and sets the adjusted minimum power value L. MIN,1 automatically reverts to a previously or originally specified minimum power value L, for example, one specified by the manufacturer. MIN,0 back, so that the entire power modulation range L is available again MIN,0 to L MAX is available.

Claims

[1] Method for operating a heating device (100) with a variable heating power (L) within a power modulation range, wherein the power modulation range includes values ​​from a predefinable minimum power (L) MIN ) up to a rated power (L MAX ) exhibits, encompassing the steps • Providing a burner (200) to generate the heating power (L) by burning a fuel-air mixture flow (AB) producing at least one flame (F), • Providing an optical monitoring device (300) for generating a measured value (M) corresponding to an optical radiation (S) of the flame (F), • In a first comparison, during heating operation of the heating device (100), compare the measured value (M) with a limit value (G), in particular by means of a control device (400), and • Determine, based on the result of the first comparison, whether a flame (F) is present, characterized by, that in a further step, in particular by means of the control device (400) a value of the minimum power (L MIN ) is adjusted if no flame (F) is detected during heating operation or if the measured value (M) is detected to be within a tolerance range just above the limit value (G). [2] Method according to claim 1, characterized by , that the value of the minimum power (L MIN ), in particular by means of the control device (400), in particular by 2-10%, preferably by 5%, based on the value of the rated power (L MAX ), is increased, whereby the value of the minimum power (L MIN ) at most up to the value of the rated power (L MAX ) is increased. [3] Method according to any one of the preceding claims, characterized by , that the value of the minimum power (L MIN ), in particular by means of the control unit (400), is set to the current value of the heating power (L). [4] Method according to any one of the preceding claims, characterized by , that the value of the minimum power (L MIN ), in particular by means of the control device (400), is adjusted, in particular increased, until the current measured value (M) is greater than or equal to the limit value (G). [5] Method according to any one of the preceding claims, characterized by , that the adjusted value of the minimum power (L MIN ), in particular by means of the control unit (400), is stored in a memory module. [6] Method according to any one of the preceding claims, characterized by , that the adjusted value of the minimum power (L MIN ), in particular by means of the control unit (400), a current and / or subsequent heating operation is based on. [7] Method according to any one of the preceding claims, characterized by , that an initial warning message, in particular by means of the control unit (400), is issued when the value of the minimum power (L MIN ) is adjusted. [8] Method according to any one of the preceding claims, characterized by , that a second warning message is issued, in particular by means of the control unit (400), when the adjusted value of the minimum power (L) MIN ) a predefinable threshold, in particular 50% of the rated power (L MIN ), exceeds. [9] A method according to any one of the preceding claims, comprising the steps • Providing a memory module with stored expected values ​​(E) for measured values ​​(M) generated at predefinable operating points of the heating device (100), • Generating measured values ​​(M) at at least one of the predefinable operating points, preferably at several or all operating points, • To identify, in a second comparison, deviations between the expected values ​​(E) and the corresponding measured values ​​(M), • Based on the deviations, diagnose and / or identify a cause for the deviations. [10] Method according to any one of the preceding claims, characterized by that a value of a predefinable burner start power L ST , in particular by means of the control device (400), is increased when the value of the adjusted minimum power (L MIN ) greater than a previously or originally specified burner start power value L ST is. [11] Method according to any one of the preceding claims, characterized by , that in a further step, in particular by means of the control device (400), the value of the minimum power (L MIN ) adjusted, in particular reduced and / or to a previously or originally specified minimum power value (L MIN ) is reset, especially when maintenance of the heating device (100) and / or the optical monitoring device (300) is detected. [12] Method according to any one of the preceding claims, characterized by , that a fuel (B) which is combusted in the burner (200) has at least 50 vol% molecular hydrogen. [13] Computer program which is configured to perform all steps of the method according to any one of claims 1 to 12. [14] Machine-readable storage medium on which the computer program according to claim 13 is stored. [15] Heating device (100) with a variable heating power (L) within a power modulation range, wherein the power modulation range includes values ​​from a predefinable minimum power (L) MIN ) up to a rated power (L MAX ) exhibits, comprehensive • a burner (200) for generating the heating power (L) by burning a fuel-air mixture flow (AB) producing at least one flame (F), • an optical monitoring device (300) for generating a measured value (M) corresponding to an optical radiation (S) of the flame (F), • a control device (400), configured for comparing, in a heating operation of the heating device (100), in a first comparison, the measured value (M) with a limit value (G) and recognizing, based on a result of the first comparison, whether a flame (F) is present, characterized by that the heating device (100), in particular the control device (400), is configured to determine a minimum power value (L) using a method, in particular according to one of the preceding claims. MIN ) to adjust if the control unit (400) does not detect a flame (F) in heating mode or detects the measured value (M) as being within a tolerance range just above the limit value (G). [16] Heating device (100) according to claim 15, characterized by, that the burner (200) is designed to safely combust a fuel stream (B) containing at least 50 vol% molecular hydrogen.

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