DE102023101531A1 - Method for operating a heating device, computer program, control device and heating device - Google Patents

Abstract

A method is proposed for operating a heating device (1), the heating device (1) having a conveying device (2) for conveying a combustion mixture of fuel and combustion air to a burner (3) and a UV sensor (13) for monitoring a flame of the heating device (1), which delivers a signal proportional to the UV radiation intensity over the entire measuring range. The method comprises at least the following steps: a) operating the heater (1) at a first operating point (21) with an assumed lambda value λsoll and detecting a value S1 of a feed parameter which allows a conclusion to be drawn about the combustion air mass flow, b) changing the combustion air mass flow until the signal from the UV sensor (13) has changed by a predetermined value Δλsoll and then detecting the value S2 of the feed parameter and/or determining a gradient of the feed parameter when the combustion air mass flow changes, c) determining a lambda value λactual of the first operating point in step a), based on the values S1 and S2 of the feed parameter and taking into account a predetermined relationship, and evaluating the λactual and/or the gradient determined in step b). In addition, a heater (1), a control device (7) and a computer program are specified.

Description

The invention relates to a method for operating a heating device, a computer program, a regulating and control device and a heating device.

A large number of heating devices are known which feed a combustion mixture of a fuel, in particular a fuel gas such as natural gas or hydrogen, conveyed by a conveying device to a burner and burn it, and use the resulting heat to supply a building.

These heaters usually have a control of the composition of the combustion mixture and thus the combustion air ratio (also known as lambda or air ratio). One or more flame monitoring signals are usually used for this, which on the one hand monitor the presence of a flame on the burner and on the other hand can also be used to control the combustion air ratio.

Often, an ionization current of the flame is measured for flame monitoring, from which the existing combustion air ratio can be determined. However, a robust measurement of the ionization current is not possible in hydrogen-powered heaters, since the combustion of hydrogen does not produce enough free and measurable charge carriers. Therefore, other sensor systems are used in hydrogen-powered heaters, in particular a measurement of the radiation emitted by the flame, especially UV (ultraviolet) radiation.

In particular, UV sensors for measuring the UV radiation emitted by the flame can be subject to sensor drift, i.e. a slow change in the signal under the same measuring conditions. When used to control the combustion air ratio, a sensor drift can lead to control in an unsafe range, for example a combustion mixture with too high a proportion of fuel (hydrogen) with a combustion air ratio λ < 1.0, i.e. a rich combustion mixture. The sensor drift can be caused by aging of the sensor, particularly in the case of a UV sensor, but also by contamination of the sensor or a protective screen arranged between the UV sensor and the flame, for example due to the effects of combustion products.

A sensor drift can be monitored, for example, using a parallel lambda sensor. However, lambda sensors are expensive and the heater must be structurally modified for this purpose.

Based on this, the object of the invention is to propose a method for operating a heating device, a computer program, a control and regulating device and a heating device which at least partially overcome the problems of the prior art described. The invention is intended to enable verification and correction of a sensor signal from a temperature sensor for regulating a combustion mixture of a heating device, in particular a heating device operated with hydrogen.

In addition, the method should be suitable for being carried out at least partially automatically and require as few structural changes as possible compared to a state-of-the-art heating device.

These objects are achieved by the features of the independent patent claims. Further advantageous embodiments of the solution proposed here are specified in the independent patent claims. It is pointed out that the features listed in the dependent patent claims can be combined with one another in any technologically reasonable manner and define further embodiments of the invention. In addition, the features specified in the patent claims are specified and explained in more detail in the description, with further preferred embodiments of the invention being presented.

1. a) Betreiben des Heizgerätes in einem ersten Betriebspunkt mit einem (angenommenen bzw. vorgegebenen) Lambdawert λ_Soll und Erfassen eines Wertes S1 eines Zuführparameters, der einen Rückschluss auf den zugeführten Massestrom Verbrennungsluft zulässt,
2. b) Ändern des Massestromes Verbrennungsluft bis das Signal des UV-Sensors sich um einen vorgegebenen Wert Δλ_Soll geändert hat und anschließendes Erfassen eines Wertes S2 des Zuführparameters, der einen Rückschluss auf den Massestrom Verbrennungsluft zulässt und/oder Ändern des Massestromes Verbrennungsluft und Bestimmen eines Gradienten des Signals des UV-Sensors bei der Änderung des Massestromes Verbrennungsluft,
3. c) Bestimmen eines (aktuellen oder tatsächlichen) Lambdawertes λ_Ist des ersten Betriebspunktes in Schritt a), anhand der Zuführparameter S1 und S2 und unter Einbeziehung eines vorgegebenen Zusammenhanges, und Bewerten des λ_Ist und/ oder des in Schritt b) bestimmten Gradienten.

A first method for operating a heating device contributes to this, wherein the heating device has a conveying device for conveying a combustion mixture of fuel and combustion air to a burner and a UV sensor for monitoring a flame of the heating device, which delivers a signal proportional to UV radiation intensity over the entire measuring range. The first method comprises at least the following steps:

1. a) Operating the heater at a first operating point with a (assumed or specified) lambda value λ _target and recording a value S1 of a supply parameter which allows a conclusion to be drawn about the supplied mass flow of combustion air,
2. b) Changing the combustion air mass flow until the signal of the UV sensor _has changed by a predetermined value Δλ target and then recording a value S2 of the feed parameter that allows a conclusion to be drawn about the combustion air mass flow and/or changing the combustion air mass flow and determining a gradient of the signal of the UV sensor when the combustion air mass flow changes,
3. c) Determining a (current or actual) lambda value λ _Ist of the first operating point in step a), based on the feed parameters S1 and S2 and taking into account a predetermined relationship, and evaluating the λ _Ist and/or the gradient determined in step b).

• a1) Betreiben des Heizgerätes in einem Betriebspunkt mit einem (angenommenen bzw. vorgegebenen) Lambdawert λ_Soll,
• b1) Erhöhen des Massestromes Verbrennungsluft, bis eine Änderung des Signals des UV-Sensors auftritt und erfassen des Wertes SG eines Zuführparameters, der einen Rückschluss auf den zugeführten Massestrom Verbrennungsluft zulässt, und
• c1) Vergleichen des erfassten Wertes SG mit einem Wert SG_Soll der einen vorgegebenen spezifischen Parameter des UV-Sensors darstellt.

In addition, a second method for operating a heating device that can be used as an alternative is proposed. The heating device has at least one conveying device for conveying a combustion mixture of fuel and combustion air to a burner and a UV sensor for monitoring a flame of the heating device, which delivers a constant signal in a saturation range of the UV radiation intensity. The second method comprises at least the following steps:

• a1) Operating the heater at an operating point with a (assumed or specified) lambda value λ _Soll ,
• b1) Increasing the combustion air mass flow until a change in the signal of the UV sensor occurs and recording the value SG of a feed parameter that allows a conclusion to be drawn about the supplied combustion air mass flow, and
• c1) Comparing the measured value SG with a value SG _Target which represents a given specific parameter of the UV sensor.

Steps a), b) and c) or a1), b1) and c1) can be carried out at least once in the order given. In particular, steps a) to d) can be carried out at regular (or irregular, needs-based selected) intervals (hourly, minutely, secondly) during operation of a heating device. The methods are used in particular to check a signal from a UV sensor for flame monitoring and/or a set combustion air ratio of the combustion mixture.

One idea of the invention and of the first and second methods is that for each heat output (modulation point) of the heater and an associated (set target) lambda value, a change in the mass flow of combustion air (in particular when the opening position of the gas valve is simultaneously constant) leads to a specific change in the signal of a UV sensor for flame monitoring, which can be assigned to an (actual) lambda value. In other words, a lambda value of a combustion in a heater determined using a signal from a UV sensor can be verified by changing the supplied mass flow of combustion air and recording and evaluating the changes in the mass flow of combustion air and the corresponding change in the signal of the UV sensor.

The specified relationship used in step c) can be a characteristic map that maps a signal from a UV sensor of a flame monitor for a relevant lambda range and a relevant power range of the heater. The determined change in the supply parameter or the mass flow of combustion air (for the defined change in the signal of the UV sensor) can be assigned a start lambda (lambda at the start of the method proposed here) based on the specified relationship or the characteristic map. The relevant relationship can also be understood or given as a large number of relationships for different powers (modulation or load point), whereby both the lambda and the mass flow of combustion air can then be specified on one axis, since both are in a proportional relationship for a heater power. From the start lambda determined in this way, a correction factor for the gas quantity for operating the heater can now be determined, which corrects deviations of the determined start lambda (λ _start ) compared to the lambda assumed by the heater (or the combustion control) (λ _target ): $$KOrrektureaktO{r}_{GasmenGe}=\frac{{\lambda }_{Start}}{{\lambda }_{SOll}}\ast IstGasmenGe$$

At least two different types of UV sensors (or together if necessary) can be used for flame monitoring. Type A is characterized by a proportional signal from the UV sensor over the entire measuring range. Type B is characterized by a constant signal in a saturation range of the intensity of the UV radiation detected. A type B UV sensor therefore has a sensor-specific limit value for the UV radiation detected above which the UV sensor outputs a constant signal. Since a lambda value can be assigned to an intensity of UV radiation, the sensor-specific limit value can also be specified as SG _target , i.e. a sensor value above which a constant sensor value is output. A type B UV sensor can generate a signal that increases or decreases with the intensity of the UV radiation detected below the sensor-specific limit value.

The inventive idea can be implemented with the UV sensor type A in particular using the first method and with the UV sensor type B in particular using the second method.

The heating device can comprise at least one heat generator, in particular a gas condensing boiler, which releases heat energy by burning a fuel and can transfer it to a heating circuit via at least one heat exchanger, whereby consumers of the heating circuit can be connected to the heating device via a flow and a return. The exhaust gases produced during combustion can be fed to an exhaust system via an exhaust duct of the heating device. In the heating device, a circulation pump can be set up in the heating circuit to circulate a heat transfer medium (heating water), whereby heat transfer medium heated via a heating flow can be fed to consumers, such as convectors or surface heating systems, and can be returned to the heat generator or the at least one heat exchanger via a heating return.

For this purpose, the heater can have a conveying device, in particular a fan, which can supply a combustion mixture of combustion air and fuel to a burner of the heater. The conveying device can comprise a power control, in particular a speed controller. The heater can have an electronic gas-air connection in which a signal from a flame monitor can be used to determine the presence of a flame and a lambda value of the combustion, so that it can be regulated. The heater can be set up in particular to burn hydrogen as a fuel or a mixture containing hydrogen. The mixture can have a hydrogen content of at least 80% or at least 90%. A method proposed here can in principle also be carried out with other fuels, in particular combustible gases such as natural gas or liquefied petroleum gas.

The heater can have a flame monitor with a UV sensor, i.e. a sensor for detecting the ultraviolet radiation emitted by the flame. The UV sensor can be arranged in the immediate vicinity of the burner of the heater or a flame that forms on the burner. For example, the UV sensor can be attached to a burner door of a combustion chamber of the heater, if necessary with a protective glass between the UV sensor and the flame or burner, which protects the UV sensor from the effects of high temperatures and contamination by combustion products. UV sensors are often subject to age-related sensor drift, which can be advantageously compensated for simply and safely using a method presented here.

According to one embodiment, the supplied mass flow of fuel (and thus the opening position of the gas valve) can remain constant during the implementation of steps a) to c), so that a change (increase) in the lambda value occurs during the implementation of step c). By increasing the value, it can advantageously be ensured that the heater does not assume unsafe operating states during the implementation of a method proposed here.

It is understood that for a method proposed here, the signals of several (possibly different) UV sensors and thus also several detected signals from UV sensors can be included.

To carry out a method proposed here, the heater can be in operation and a control system of the heater can set a lambda value based on a signal from a UV sensor. To carry out the method, no modulation of the heater, i.e. no change in the operating point and in particular an opening position of the gas valve of the heater and thus the supplied mass flow of fuel gas remain constant.

In the first method proposed here, according to step a), the heater can be operated at an operating point with an assumed lambda value λ _target and a signal S1 can be recorded, which allows a conclusion to be drawn about the mass flow of combustion air. The operating point can indicate a heat output of the heater (which can correspond to a heat requirement) for which a lambda can be set according to a lambda control curve using the flame monitoring, i.e. the signal from at least one UV sensor. This can be done, for example, by regulating the supplied mass flow of fuel gas via an opening position of the gas valve.

According to step b), the combustion air mass flow can be changed until the signal from the UV sensor has changed by a predetermined value Δλ _Soll . The feed parameter S2 is then recorded, which allows a conclusion to be drawn about the combustion air mass flow. In this context, it is noted that the predetermined value Δλ _Soll refers to the signal from the UV sensor and can therefore also be described or understood as ΔUV _Soll , i.e. as a predetermined change in the signal from the UV sensor.

In principle, when carrying out the first method, the combustion air mass flow can be changed in both directions, i.e. increased or decreased. However, since a decrease in the combustion air mass flow leads to a decrease in the combustion lambda value (or an increased proportion of fuel in the combustion mixture), critical operating conditions of the heater can occur. For this reason, increasing the combustion air mass flow in step b) is advantageous.

When carrying out step b), a Δλ _target can be specified, for example a change in the signal of the UV sensor by 1 V [volt], which can mean a reduction to 2 volts for an initial value of 3 volts. After the specified change has been achieved, the value S2 of the feed parameter can be recorded.

Alternatively or cumulatively, when the combustion air mass flow changes, a gradient of the UV sensor signal (caused by the change) (or, at an operating point, a gradient of the feed parameter) can be determined. A start lambda value λ _Ist can also be assigned based on the gradient, whereby only a small change in the sensor value of the UV sensor (and the combustion air volume flow) may be necessary to determine the gradient. To determine the gradient of the UV signal, the combustion air mass flow should be changed with a constant gradient. Table 1 below shows, purely as an example and for explanation, an assignment or a specified relationship of a start lambda value λ _Ist to a gradient of the UV signal determined in step b) (given in V/s [volts per second]) λ _Ist = f(Gradient _UV ) for a defined output (operating point) of the heater: Table 1 Gradient signal UV sensor [V/s] Start Lambda λ _Actual 3.5 1.5 1 2.1 0.203 2.4 0.0958 3 0.005 5

According to a step c), a (start) lambda value λ _Ist of the first operating point in step a) can be determined based on the values S1 and S2 of the feed parameter and taking into account a predetermined relationship, and an evaluation of the λ _Ist and/or the gradient determined in step b) can be carried out. In this case, an evaluation can in particular include a comparison of the determined lambda value λ _Ist with the lambda value λ _Soll (assumed by the control system).

wobei S_λ=1 den Sensorwert S bei einem Lambdawert von 1 angibt, bestimmt werden.According to one embodiment, in a step d), a change in the lambda value Δλ _Ist caused by the change in the mass flow of combustion air can be calculated using the relationship $\Delta {\lambda }_{Ist}=\frac{S_1}{S_{\lambda =1}}-\frac{S_2}{S_{\lambda =1}},$

where S _λ=1 indicates the sensor value S at a lambda value of 1.

bestimmt werden. Der Korrekturfaktor K_P ermöglicht eine Anpassung der Lambdaregelkurve des Heizgerätes an einer Drift des Sensorwertes des UV-Sensors.According to one embodiment, in a step e) a correction factor K _P of a lambda control curve with $K_P=\frac{{\lambda }_{SOll}}{{\lambda }_{Ist}}$

The correction factor K _P enables the lambda control curve of the heater to be adjusted to a drift in the sensor value of the UV sensor.

Hierbei bezeichnet Gasventilsollschrittzahl_Basis die Gasventilsollschrittzahl die dem von der Regelung angenommenen λ_Soll entspricht.According to one embodiment, a corrected gas valve target step number (which corresponds to an opening width) of the gas valve can be determined by means of the determined correction factor K _P as follows: $$GasventilsOllscHrittzaH{l}_{kOrriGiert}=\frac{GasventilsOllscHrittzaH{l}_{Basis}}{K_P}$$

Here, gas valve setpoint step number _base refers to the gas valve setpoint step number that _corresponds to the λ setpoint assumed by the control system.

In the second method, which is particularly suitable for a type B UV sensor with a saturation range of the signal, the heater can be operated at an operating point with an assumed lambda value λ _desired according to step a1).

According to a step b1), the mass flow of combustion air can be increased until a change in the signal of the UV sensor occurs and the value SG of the feed parameter can be recorded. In other words, the lambda value is increased by increasing the supplied mass flow of combustion air until the UV sensor leaves the saturation range, which is indicated by a change in the signal of the UV sensor. The corresponding value SG of the feed parameter can be recorded here.

According to a step c1), the recorded value SG can be compared with a value SG _target that represents a predetermined specific parameter of the UV sensor. The value SG _target can have been determined in advance on a reference heater in laboratory tests.

bestimmt werden. Mittels des Korrekturfaktors Ks kann eine Lambda-Regelkurve des Heizgerätes an eine Veränderung des Signals des UV-Sensors (beispielsweise aufgrund von Alterung) kompensiert werden.According to one embodiment, in an optional step d1), a correction factor Ks of a lambda control curve with $K_S=\frac{SG}{S{G}_{SOll}}$

Using the correction factor Ks, a lambda control curve of the heater can be compensated for a change in the signal of the UV sensor (for example due to aging).

According to one embodiment, in steps a), a1), b) and/or b1), the feed parameter which allows a conclusion to be drawn about the mass flow of combustion air can be a speed of a conveying device designed as a fan, a control signal of a controller of the conveying device and/or a signal of a mass flow sensor (volume flow sensor) in a combustion air feed.

In this context, it is noted that a mass flow (combustion air, fuel or a mixture of both) can also characterize a volume flow and vice versa. Thus, a mass flow can easily be converted into a volume flow and vice versa if the density and temperature of the medium are known.

According to a further embodiment, information about a detected potentially critical state of the heater can be displayed via a display device (external or integrated into the heater) and/or made available for retrieval via a network, in particular the Internet, and/or sent as a message. For example, the information can be made available for retrieval on an appliance interface of the heater or on a network storage device (cloud). In this way, for example, a user/operator of the heater and/or a specialist company can advantageously be given information about a problem within the scope of carrying out a method proposed here by means of a message, and the specialist company can plan and carry out an appointment for maintenance and/or repair accordingly. In particular, this can bring about a rapid end to a fault state of the heater.

• - eines Korrekturfaktor K_S oder K_P größer einem Grenzwert,
• - einer Abweichung des Wertes SG von SG_Soll oberhalb eines Grenzwertes,
• - des Gradienten des Zuführparameters oberhalb oder unterhalb eines Grenzwertes,
• - einer Abweichung des λ_Ist von λ_Soll oberhalb eines Grenzwertes, und/ oder
• - einer Abweichung von Δλ_Ist von Δλ_Soll oberhalb eines Grenzwertes.

In this context, a critical condition of the heater can be indicated, for example, by detecting:

• - a correction factor K _S or K _P greater than a limit value,
• - a deviation of the value SG from SG _target above a limit value,
• - the gradient of the feed parameter above or below a limit value,
• - a deviation of λ _actual from λ _target above a limit value, and/or
• - a deviation of Δλ _actual from Δλ _target above a limit value.

According to a further aspect, a computer program is also proposed which is set up to (at least partially) carry out a method presented here. In other words, this relates in particular to a computer program (product) comprising commands which, when the program is executed by a computer, cause the computer to carry out a method proposed here. The computer program can in particular be executed on a control and regulating device of the heating device.

According to a further aspect, a machine-readable storage medium is also proposed on which the computer program is stored.

The machine-readable storage medium is usually a computer-readable data carrier.

According to a further aspect, a control device for a heating device is also proposed, set up to carry out a method proposed here. The control device can for example have a processor for this purpose and/or have one. In this context, the processor can for example carry out the method stored in a memory (of the control device). The control device can for this purpose be electrically connected in particular to a conveyor device and a flame monitor. In addition, data recorded or required in the context of carrying out a method proposed here can be stored in a memory of the control device.

According to a further aspect, a heating device is also proposed, having a control and regulating device as proposed here. The heating device can be a gas heating device, in particular a hydrogen-operated gas heating device. The gas heating device can have a burner and a conveying device with which a mixture of fuel (hydrogen) and combustion air can be supplied to the burner. The heating device can also have a flame monitor, comprising at least one UV sensor.

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

A method for operating a heater, a computer program, a control and regulating device and a heater are therefore specified here, which at least partially solve the problems described with reference to the prior art. In particular, the method for operating a heater, the computer program, the control and regulating device and the heater help to verify a signal from a UV sensor of a flame monitor of a heater and, if necessary, to compensate for any sensor drift that has occurred.

Another advantage is that a method proposed here can be carried out entirely by computer and therefore does not require any structural changes and in particular no additional components on a heating device.

• 1: einen Ablauf eines hier vorgeschlagenen Verfahrens,
• 2: ein hier vorgeschlagenes Heizgerät, und
• 3 und 4: Parameterverläufe, die sich bei der Durchführung eines hier vorgeschlagenen Verfahrens einstellen können.

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 given. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to 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:

• 1 : a sequence of a procedure proposed here,
• 2 : a heater proposed here, and
• 3 and 4 : Parameter curves that can occur when carrying out a procedure proposed here.

1 shows an example and schematically a sequence of a method proposed here. The execution of steps a), b) and c) shown with blocks 110, 120 and 130 can be carried out at least once in the order given in a regular process sequence. The method serves to operate the heating device 1, in particular to verify a lambda value of the combustion on a burner 3 of the heating device 1 determined with a UV sensor 13, and if necessary to correct the same. The method can in particular be carried out on a heating device 1 that is in operation.

2 shows, by way of example and schematically, a heating device 1 proposed here. This can comprise a burner 3 arranged in a combustion chamber 8. Combustion air can be sucked in by a conveying device 2, in particular designed as a fan, via a combustion air supply 4, in which a mass flow sensor 10 can be arranged. The conveying device 2 can be connected to a speed controller which can regulate a speed n of the conveying device 2 by means of a pulse width modulated (PWM) signal. A gas valve 5 can add combustion gas from a gas supply 12 to the sucked-in air mass flow of combustion air and comprise a safety valve and a gas control valve for controlling the mass flow of combustion gas to be added. The mixture of combustion gas and combustion air produced can flow via a mixture channel 11 to the burner 3 and be burned there. The combustion products can be discharged after combustion via an exhaust system 9.

The heating device 1 proposed here can be designed in particular for the combustion of hydrogen. Flame monitoring can be carried out by means of a UV sensor 13. The UV sensor 13 can be attached to a burner door and can detect the UV radiation emitted by the flame through a protective glass 6. In addition, a signal from the UV sensor 13 can be used to control combustion (in particular to control the lambda of the combustion).

A control and regulating device 7 can be set up to regulate the heating device 1. For this purpose, it can be electrically connected, for example, to the conveyor device 2, the gas valve 5, the UV sensor 13 and a network 14 (Internet). The control and regulating device 7 can be set up to carry out a method proposed here.

The 3 shows an example of a lambda control curve 15 of a heater 1. This shows a settable course of a signal Vuv given in volts [V] as a function of the power P, given in percent [%] of the nominal power of the heater 1. The signal Vuv represents a target signal, whereby a sensor drift, triggered for example by aging or contamination, can lead to deviations. A lambda control curve 15 can be stored, for example, in a memory of the control and regulation device 7.

The 4 shows a predetermined relationship (characteristic map) given by curves of signals of equal intensity of the UV sensor 13 as a function of the power P of the heater 1 and the lambda λ. Shown are a first curve 16 for a signal of 1 volt, a second curve 17 for a signal of 2 volts, a third curve 18 for a signal of 3 volts and a fourth curve 19 for a signal of 4 volts. The curves 16, 17, 18, 19 can be determined in advance on a reference heater in laboratory tests and can also be understood as signal lines of the UV sensor 13. As an example, in the 4 At a power of 15 kW [kilowatt], a lambda change 20 is shown, which can occur when the combustion air mass flow changes (according to block 120, step b)).

The following is an example of Table 2, which contains a data set of a given relationship or a characteristic map for a heater 1 with an output of 15 kW when burning pure hydrogen: Table 2 (Intersection) point Lambda λ Combustion air mass flow [kg/h] UV signal [volt] 24 5.0 76.6 1.0 23 3.0 45.9 2.0 22 2.4 36.8 3.0 21 2.1 32.1 4.0

The following Table 3 shows the change in the parameters from Table 2 when implementing a (first) procedure proposed here: Table 3 the change Lambda difference Change in combustion air mass flow [kg/h] Change signal UV sensor [Volt] Point 21 to point 22 0.3 30.7 -1 Point 22 to point 23 0.6 9.1 -1 Point 23 to point 24 2 4.7 -1

From a known change in the combustion air mass flow (determined in step b) and a corresponding change in the signal of the UV sensor 13, a (starting) lambda λ _actual can thus be determined.

5 shows an example signal curve of a UV sensor 13 of type B. The signal of the UV sensor 13 increases with increasing irradiance E (given in watts/square meter [W/m ² ]) until a sensor-specific limit value SG _Soll is reached. In a saturation range above this, the signal of the UV sensor 13 SG _Soll is output regardless of the irradiance E.

6 shows an alternative signal curve of a UV sensor 13 of type B. In this case, the signal of the UV sensor 13 increases below the saturation range in contrast to the 5 until a signal maximum is reached at an irradiance E of 0. A method proposed here, in particular the second method, can be used with a UV sensor 13 of type B with a signal curve according to 5 or 6 be performed.

7 shows an example of a signal curve of a UV sensor 13 of type A. The signal of the UV sensor 13 of type A increases proportionally with increasing irradiance E.

8th also shows, by way of example, a diagram which assigns a determined gradient of the signal of the UV sensor 13 (of sensor type A) to a (starting) lambda λ _Actual at a heater output of 15 kW. The gradient of the UV signal is given here in volts per second [V/s].

In block 110, according to step a), the heater 1 can be operated at a first operating point 21 with an assumed lambda value λ _target and a value S1 of a feed parameter can be recorded, which allows a conclusion to be drawn about the mass flow of combustion air. The feed parameter can in particular be a speed of the conveyor 2, a control signal (in particular a PWM signal) of the speed controller of the conveyor 2 or a value determined by the mass flow sensor 10. The heater 1 can in this case be operated at an operating point according to 3 operated using the signal from the UV sensor.

• - bis das Signal des UV-Sensors (13) sich um einen vorgegebenen Wert Δλ_Soll geändert hat und anschließend ein Erfassen des Wertes S2 des Zuführparameters, und/oder
• - ein Bestimmen eines Gradienten des Zuführparameters bei der Änderung des Massestromes Verbrennungsluft. Ein Beispiel für eine Änderung des Zuführparameters derart, dass sich das Signal des UV-Sensors von 3 Volt auf 2 Volt (Δλ_Soll) ändert, ist in 3 als Lambdaänderung 20 angegeben, bedingt durch ein Ändern des Massestromes Verbrennungsluft, wobei in einem zweiten Betriebspunkt 22 das Signal des UV-Sensors den Wert von 2 Volt erreicht hat.

In block 120, according to step b), the combustion air mass flow can be changed,

• - until the signal of the UV sensor (13) _has changed by a predetermined value Δλ setpoint and then the value S2 of the feed parameter is recorded, and/or
• - determining a gradient of the feed parameter when the mass flow of combustion air changes. An example of a change in the feed parameter such that the signal of the UV sensor changes from 3 volts to 2 volts (Δλ _setpoint ), is in 3 indicated as lambda change 20, caused by a change in the combustion air mass flow, whereby in a second operating point 22 the signal of the UV sensor has reached the value of 2 volts.

In block 130, according to step c), a lambda value λ _Ist of the first operating point in step a) can be determined based on the values S1 and S2 of the feed parameter and taking into account a predetermined relationship, and/or determining a gradient of the signal of the UV sensor 13 taking into account a predetermined relationship, for example in 4 given as a map. In the example according to 4 At an output of 15 kW, changing the combustion air mass flow can lead to a measuring line 20 being measured from the first intersection point 21 to the second intersection point 22. Using the measuring line 20, the lambda value λ _actual can be determined at the start of the process (i.e. before changing the combustion air mass flow according to block 120 (step b)), which here is at the first intersection point 21. The determined lambda value λ _actual can now be compared with the lambda value λ _target assumed (by the control of the heater 1) and deviations can be determined.

As a precaution, it should be noted that the numerals used here ("first", "second", ...) primarily serve (only) to distinguish between several similar objects, sizes or processes, and in particular do not necessarily specify a dependency and/or sequence of these objects, sizes or processes. If a dependency and/or sequence is required, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described design. If a component can occur multiple times ("at least one"), the description of one of these components can apply equally to all or part of the majority of these components, but this is not mandatory.

List of reference symbols

1

heater

2

Conveyor system

3

burner

4

Combustion air supply

5

Gas valve

6

Protective glass

7

Control and regulation device

8th

Combustion chamber

9

Exhaust system

10

Mass flow sensor

11

Mixture channel

12

Fuel gas supply

13

UV sensor

14

network

15

Lambda control curve

16

Course 1 Volt

17

Course 2 Volt

18

Course 3 Volt

19

Course 4 Volt

20

Measuring line

21

first intersection

22

second intersection point

Claims (11)

Method for operating a heating device (1), at least comprising a conveying device (2) for conveying a combustion mixture of fuel and combustion air to a burner (3) and a UV sensor (13) for monitoring a flame of the heating device (1), which delivers a signal proportional to the UV radiation intensity over the entire measuring range, wherein the method comprises at least the following steps: a) operating the heating device (1) at a first operating point (21) with a lambda value λ _desired and detecting a value S1 of a feed parameter which allows a conclusion to be drawn about the mass flow of combustion air, b) changing the mass flow of combustion air until the signal of the UV sensor (13) _has changed by a predetermined value Δλ desired and then detecting a value S2 of the feed parameter and/or changing the mass flow of combustion air and determining a gradient of the feed parameter when the mass flow of combustion air changes, c) determining a lambda value λ _actual of the first operating point (21) in step a), based on the values S1 and S2 of the feed parameter and taking into account a predetermined relationship, and evaluating the lambda value λ _actual and/or the gradient determined in step b). Method for operating a heater (1), at least having a conveying device (2) for conveying a combustion mixture of fuel and combustion air to a burner (3) and a UV sensor (13) for monitoring a flame of the heater (1), which delivers a constant signal in a saturation range of the UV radiation intensity, wherein the method comprises at least the following steps: a1) operating the heater (1) at a first operating point (21) with a lambda value λ _desired , b1) increasing the mass flow of combustion air until a change in the signal of the UV sensor (13) occurs and detecting a value SG of the feed parameter, and c1) comparing the detected value SG with a value SG _{desired' which} represents a predetermined specific parameter of the UV sensor (13). Procedure according to Claim 1 , whereby in a step d) a change in the lambda value Δλ _Ist caused by the change in the mass flow of combustion air is calculated using the relationship $\Delta {\lambda }_{Ist}=\frac{S_1}{S_{\lambda =1}}-\frac{S_2}{S_{\lambda =1}}$

where S _λ=1 indicates the sensor value S at a lambda value of 1.0. Procedure according to Claim 3 , whereby in a step e) a correction factor K _P of a lambda control curve with $K_P=\frac{{\lambda }_{SOll}}{{\lambda }_{Ist}}$

is determined, where λ _Ist corresponds to the lambda value when detecting the value S1 of the feed parameter in step a). Method according to one of the Claims 1 , 3 or 4 , whereby in step b) the mass flow of combustion air is increased. Procedure according to Claim 2 , wherein in a step d1) a correction factor Ks of a lambda control curve (15) with $K_S=\frac{SG}{S{G}_{SOll}}$

is determined. Method according to one of the preceding claims, wherein the feed parameter which allows a conclusion to be drawn about the mass flow of combustion air is selected from the following group: speed of a conveying device (2) designed as a fan, control signal of a controller of the conveying device (2), signal of a mass flow sensor in a combustion air feed (4). Method according to one of the preceding claims, wherein upon detection - of a correction factor K _S or K _P greater than a limit value, - of a deviation of the value SG from SG _target above a limit value, - of a gradient of the feed parameter above or below a limit value, and/or - of a deviation of λ _actual from λ _target above a limit value, - of a deviation of Δλ _actual from Δλ _target above a limit value, information on this is displayed or made available for retrieval via a network (14) or as a message is shipped and/or the heater (1) is put into a fault state. Regulating and control device (7) of a heating device (1), designed to carry out a method according to one of the preceding claims. Heating device (1), comprising a conveying device (2) for conveying a mass flow of combustion air and a UV sensor (13) for monitoring a flame of the heating device (1) and means, arranged for carrying out a method according to one of the Claims 1 until 8th . Computer program comprising commands which cause a heating device (1) to Claim 10 the procedural steps of a procedure according to one of the Claims 1 until 8th executes.

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