EP4421386A1 - Method for operating a heating device, computer program, control and control device and heating device - Google Patents

Abstract

A method is proposed for operating a heating device (1), having a conveying device (2) for conveying a combustion mixture of fuel gas and combustion air to a burner (3) and a gas valve (5) for controlling a flow rate of fuel gas, the method comprising at least the following steps: a) detecting a volume flow V̇_Air(t₀) of combustion air (17) supplied to the burner (3) at a time t_{0 (18)}, b) opening or closing the gas valve (5), c) detecting the volume flow V̇_Air(t) of combustion air at a time t (19) after opening or closing the gas valve (5) in step b), d) determining a ratio R(t) with- Rt=V˙AirtV˙Airt0, if the gas valve (5) was opened in step b) and with- Rt=V˙Airt0V˙Airt, if the gas valve (5) was closed in step b).The method enables checking/verifying a combustion air ratio assumed and set by the combustion control. Optionally, the combustion air ratio can be adjusted. In addition, a heater (1), a control and regulating device (7) and a computer program are proposed.

Description

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

When operating a heater, a mass flow of combustion air is usually added to a mass flow of combustion gas corresponding to a predetermined combustion air ratio and fed to a burner. The current combustion air ratio can be determined based on a recorded combustion parameter. The parameter is often an ionization current of the combustion, which can be recorded using an ionization electrode. However, the measurement of the ionization current as a control variable for combustion control cannot be carried out robustly with hydrogen as the fuel.

In heating devices using hydrogen as a fuel, other combustion parameters are therefore recorded to control the combustion, in particular a temperature of the flame and/or optical parameters, for example the UV (ultraviolet) radiation emitted by the flame. However, the sensors can be subject to sensor drift, i.e. a gradual change in the sensor signal. The sensor drift can be triggered, for example, by aging effects such as oxidation. If the signal is used as a control variable for combustion control, this can lead to a gradual change in the combustion air ratio (set by the control), which can lead to critical conditions in the heating device, for example a flashback. In addition, the energy efficiency of combustion can decrease if the combustion air ratio is shifted, or even unburned fuel can get into the exhaust gas. Last but not least, geometric tolerances of the components involved in the heater or environmental effects such as wind or exhaust gas recirculation can lead to a shift in the combustion air ratio.

The solution is EP 3 985 306 A1 It is proposed to transmit the measured value of a temperature sensor arranged in the combustion chamber to a measuring and evaluation unit, which is to monitor the measured value and its behavior over time. In addition, two redundant sensors can be present in order to increase operational reliability. The disadvantage of the proposed solution is that it can hardly detect a sensor drift or distinguish it from other effects that result in a shift in the measured value.

Based on this, it is the object of the invention 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. In particular, the invention is intended to enable safe operation 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 implemented in any technologically more meaningfully, can be combined with one another 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) Erfassen eines dem Brenner zugeführten Volumenstromes V̇_Air (t ₀) Verbrennungsluft zu einem Zeitpunkt to,
2. b) Öffnen oder Schließen des Gasventils,
3. c) Erfassen des Volumenstromes V̇_Air (t) Verbrennungsluft zu einem Zeitpunkt t nach dem Öffnen oder Schließen des Gasventils in Schritt b),
4. d) Ermitteln eines Verhältnisses R(t) mit

• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t\right)}{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}$
  
  , wenn das Gasventil in Schritt b) geöffnet wurde und mit
• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}{{\dot{V}}_{\mathit{Air}}\left(t\right)}$
  
  , wenn das Gasventil in Schritt b) geschlossen wurde.

A method for operating a heating device contributes to this. The heating device has a conveying device for conveying a combustion mixture of fuel gas and combustion air to a burner and a gas valve for controlling a flow rate of fuel gas. The method comprises at least the following steps:

1. a) Determining a volume flow V̇ _Air ( t ₀ ) of combustion air supplied to the burner at a time to,
2. b) opening or closing the gas valve,
3. c) Determining the volume flow V̇ _Air ( t ) of combustion air at a time t after opening or closing the gas valve in step b),
4. d) Determine a ratio R(t) with

• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t\right)}{{\dot{V}}_{\mathit{<figure-callout\; id="0"\; label="Air\; t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">Air</figure-callout>}}\left(t_{}\right)\left({}_0\right)}$
  
  if the gas valve was opened in step b) and
• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}{{\dot{V}}_{\mathit{Air}}\left(t\right)}$
  
  if the gas valve was closed in step b).

Steps a), b), c) and d) can be carried out at least once in the order given. In particular, steps a) to d) can be carried out at regular intervals during operation of the heater. Alternatively or cumulatively, the process can also be carried out as needed or triggered by events, for example if operating data of the heater indicate a shift in the combustion air ratio. The process is used in particular to ensure permanently safe operation of a Heating device, in particular a heating device operated with hydrogen or a hydrogen-containing mixture as fuel.

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, wherein 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 in the heating circuit can be set up to circulate a heat transfer medium (heating water), wherein 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 mixture of combustion air and fuel (hydrogen) to a burner of the heater arranged in a combustion chamber. Combustion air can refer to the air flow conveyed by the conveying device, regardless of whether this is actually fed to a combustion or is conveyed, for example during commissioning, when starting up the conveying device or during flushing processes. The conveying device can comprise a power control, in particular a speed controller. The heater can form a pneumatic gas-air connection in which a mass flow of combustion air is added to a mass flow of combustion air in accordance with a negative pressure (control pressure) of a throttle point, such as a Venturi nozzle, so that a predefined (specified) combustion air ratio (air ratio, lambda) can be set. The heater can alternatively have an electronic gas-air connection in which which can be used to draw conclusions about the flames and the combustion air ratio (also known as lambda or air ratio) based on a signal from a flame monitor, so that it can be regulated. The heater can be set up in particular to burn hydrogen as a fuel or a (fuel) mixture containing hydrogen. The mixture can have a hydrogen content of at least 80% or at least 90%.

The heater can also have a flame monitor. An ionization electrode is often used for this, which can use an ionization current from the flame to detect it. However, this principle cannot be used robustly with a hydrogen flame, as significantly fewer free charge carriers are produced when hydrogen is burned. For this reason, other methods are often used in hydrogen-powered heaters, such as detecting the electromagnetic radiation emitted by the flame, in particular infrared (IR) and/or UV (ultraviolet) radiation, or detecting the flame temperature. A signal from a flame monitor can indicate the presence of a flame and allow a conclusion to be drawn about the combustion air ratio of the flame.

Commissioning a heater can proceed as follows. First, for example, a control unit of the heater can start a conveyor, which is usually designed as a fan, to a specified starting power or starting speed. After reaching the specified starting power or starting speed, a purge phase with a specified period of time can follow, in which the mass flow of combustion air can stabilize in the flow path. At the specified starting power or starting speed, a starting volume flow of combustion air is established. Now a flow rate of fuel (starting mass flow or starting volume flow of fuel) specified for the starting power or starting speed can be supplied by setting a gas valve to a corresponding opening position. is driven. With increasing volume flow of fuel gas V̇ _Gas, the volume flow of combustion air V̇ _Air ( t ) can continuously decrease over time t and the supplied volume flow of fuel gas V̇ _Gas ( t ) can increase inversely proportionally until a predetermined combustion air ratio λ is established and an ignition process can be initiated. The described process of starting up a heater can be carried out in particular by a control device of a heater.

According to step a), a) detection of a volume flow V̇ _Air ( t ₀ ) of combustion air supplied to the burner can take place at a time t _0. The time t ₀ can represent a time during operation of the heater at which it is operated with a combustion air ratio assumed by the control. The assumed combustion air ratio can be set by the combustion control on the basis of a combustion parameter, in particular a signal from a temperature sensor for detecting a flame temperature or an optical sensor for detecting optical radiation emitted by the flame (in particular UV radiation) and a predetermined relationship between combustion parameter and combustion air ratio.

Alternatively, at time t0 the heater can also deliver a volume flow of combustion air and the gas valve can be closed. This can be the case, for example, when the burner is restarted following an interruption to carry out a process proposed here.

In particular, the recorded volume flow V̇ _Air ( t ₀ ) combustion air combustion mixture can be stored in an electronic data storage device, for example a memory of the control unit.

According to step b), the gas valve can now be opened or closed. When opening, the gas valve can be opened to a predetermined opening width, which can set a combustion air ratio (assumed by the combustion control). When closing the gas valve, it can be closed completely so that only the volume flow of combustion air conveyed by the conveying device is fed to the burner.

According to a step c), the combustion air volume flow V̇ _Air ( t ) can be recorded after the gas valve has been opened or closed at a time t . The time t can be in a predetermined period after the time t ₀ . In particular, the combustion air volume flow V̇ _Air ( t ) can be recorded continuously or over a predetermined recording period, wherein the recording period is at least partially parallel to the opening process of the gas valve and/or the fully opened gas valve.

According to one embodiment, the combustion air volume flow V̇ _Air ( t ₀ ) and/or the combustion air volume flow V̇ _Air ( t ) can be detected by means of a flow sensor (a mass flow or volume flow sensor) which can be or is arranged in a combustion air supply of the heater, for example in a silencer of a combustion air supply.

According to one embodiment, according to one of the preceding claims, in steps a) and c), the volume flow V̇ _Air ( t ₀ ) or V̇ _Air ( t ) can be deduced from the speed n of the conveyor. In particular, the speed can be kept constant or regulated. For example, during operation at time to, the target speed can be kept constant and regulated, a V̇ _Air ( t ₀ ) is set and can be recorded. The gas valve can then be closed or opened. The speed of the conveyor remains constant and a changed combustion air volume flow V̇ _Air ( t ) can be recorded. R(t) can now be determined using V̇ _Air ( t ₀ ) and V̇ _Air ( t ).

In this context, it is noted that a (gaseous) volume flow can be easily converted into a mass flow and vice versa. This can be done approximately by multiplying with a conversion factor or by making a precise conversion with knowledge of the state parameters of the gas flow to be measured, in particular the density, temperature and pressure. A reference in this document to a mass flow can therefore always be understood as a reference to a volume flow and vice versa.

• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t\right)}{{\stackrel{<figure-callout\; id="0"\; label="\; ̇\; Air\; t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">\dot{}</figure-callout>}{V}}_{\mathit{Air}}\left(t_{}\right)\left({}_0\right)}$
  
  , wenn das Gasventil in Schritt b) geöffnet wurde, und mit
• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}{{\dot{V}}_{\mathit{Air}}\left(t\right)}$
  
  , wenn das Gasventil in Schritt b) geschlossen wurde, erfolgen.

According to step d) determining a ratio R(t) with

• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t\right)}{{\stackrel{<figure-callout\; id="0"\; label="\; ̇\; Air\; t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">\dot{}</figure-callout>}{V}}_{\mathit{Air}}\left(t_{}\right)\left({}_0\right)}$
  
  if the gas valve was opened in step b) and with
• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}{{\dot{V}}_{\mathit{Air}}\left(t\right)}$
  
  if the gas valve was closed in step b).

• V̇_Gas (t) = V̇_Air (t ₀) - V̇_Air (t) bei einem Öffnen des Gasventils bzw.
• V̇_Gas (t) = V̇_Air (t) - V̇_Air (t ₀) bei einem Schließen des Gasventils
• hergeleitet werden kann.

The ratio is derived from the fact that the volume flow conveyed by the conveyor at constant speed is constant (independent of density) and the volume flow of fuel gas V̇ _Gas ( t ) is thus determined by means of

• V̇ _Gas ( t ) = V̇ _Air ( t ₀ ) - V̇ _Air ( t ) when the gas valve is opened or
• V̇ _Gas ( t ) = V̇ _Air ( t ) - V̇ _Air ( t ₀ ) when the gas valve is closed
• can be derived.

Based on the ratio R(t) determined in step d), a conclusion can be drawn about the combustion air ratio at time t or t _0. In particular, when the gas valve is closed, the combustion air ratio before closing can be determined, and when the gas valve is opened, the combustion air ratio after opening can be determined. For this purpose, the determined R(t) can be compared with a compared to a given reference range of R(t) and the combustion at time t is evaluated.

erfolgen.According to one embodiment, in one step
e) calculating a virtual combustion air ratio λ _V (t) by means of ${\mathrm{\lambda }}_V\left(\mathrm{t}\right)=\frac{R\left(t\right)}{A\times \left(1-R\left(t\right)\right)}$

take place.

The factor A represents the minimum air requirement for the combustion of the fuel gas, also known as the stoichiometric air requirement, i.e. the volume of combustion air required to burn one cubic meter of fuel gas, assuming that the combustion air has an oxygen content of 21 percent [%]. Knowing the chemical composition of the fuel, the minimum air requirement A can therefore be calculated. For example, the factor A (the minimum air requirement for combustion) is 2.381 for hydrogen (100%), 9.52 for (100%) methane, 23.8 for (100%) propane and 31 for (100%) butane. The factor A (the minimum air requirement) can be stored for this purpose, for example, in a memory of the control unit of the heater, e.g. an average value for the gases in a gas family.

und ${\mathrm{\lambda }}_V\left(\mathrm{t}\right)=\frac{R\left(t\right)}{A\times \left(1-R\left(t\right)\right)}$

der Mindestluftbedarf A in Kenntnis des Verbrennungsluftverhältnisses im Betrieb bestimmt werden.Alternatively, the minimum air requirement A could also be determined, for example from a commissioning procedure and/or with the help of other control circuits of the heater. For example, a lambda control circuit of a heater can be used for this purpose, which can regulate the combustion air ratio of the heater during operation regardless of the type of gas. In this way, after closing the gas valve with $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}{{\dot{V}}_{\mathit{Air}}\left(t\right)}$

and ${\mathrm{\lambda }}_V\left(\mathrm{t}\right)=\frac{R\left(t\right)}{A\times \left(1-R\left(t\right)\right)}$

The minimum air requirement A can be determined knowing the combustion air ratio during operation.

An alternative way of determining the minimum air requirement A could be to reduce the combustion air ratio from a non-ignitable range (thus increasing the proportion of fuel in the combustion mixture) until successful ignition takes place and thus determine an R(t) for the leanest ignitable mixture. Knowing a lambda limit of the device for ignition (i.e. the maximum lambda (combustion air ratio) with which ignition is possible), the minimum air requirement A could be calculated using the determined R(t).

According to one embodiment, an evaluation of the virtual combustion air ratio λ _V (t) could take place in step e). The evaluation is carried out in particular with a view to determining a deviation of the virtual combustion air ratio λ _V (t) from the combustion air ratio assumed (set) by the combustion control on the basis of the combustion parameter.

According to one embodiment, the evaluation according to step e) could take into account the fact that a virtual combustion air ratio λ _V (t) that is too low can indicate potentially occurring critical conditions of the heating device.

According to a further embodiment, in order to carry out a method proposed here, the burner operation can be interrupted and R(t) can be determined both when the gas valve is closed and opened. The two determined R(t) (when the gas valve is closed and opened) and/or the virtual combustion air ratios λ _V (t) derived therefrom (when the gas valve is closed and opened) can then be compared and the comparison results evaluated.

According to one embodiment, when carrying out step e), the virtual combustion air ratio λ _V (t) or the gradient G(t) determined in step d) can be compared with a (respective) reference range. Leaving the The reference range can indicate a critical operating condition, in particular a critical combustion air ratio λ. The reference range can be defined by an upper and a lower limit, whereby a virtual combustion air ratio λ _V (t) greater than the upper limit and/or smaller than the lower limit can indicate a possibly critical operating condition. The reference range can also be a limit, falling below or exceeding which can indicate a critical condition. In particular, falling below the limit can be critical, as this can indicate a low λ and thus a high proportion of fuel in the combustion mixture (rich mixture).

According to one embodiment, the reference range and/or limit value can have been determined in advance on a reference heater in (laboratory) tests and stored in a memory of the heater, in particular a control and regulating device of the heater.

According to one embodiment, when it is determined that the reference range has been left and/or that the limit value has been exceeded or not reached by the virtual combustion air ratio λ _V (t) and/or the ratio R(t) in step e), the volume flow of fuel gas V̇ _Gas can be adjusted.

berechnet wird. Der kompensierte Volumenstrom kann dann zur Berechnung des virtuellen Verbrennungsluftverhältnisses herangezogen werden.As described, a speed of the conveyor that is as constant as possible is crucial for determining R(t) or the virtual combustion air ratio λV(t). However, a short-term speed deviation can occur when the gas valve is opened or closed. According to one embodiment, this speed deviation can be compensated by additionally recording the speed n of the conveyor at time to and at time t and calculating a compensated volume flow ${\dot{V}}_{{\mathit{Air}}_{\mathit{Comp}}}\left(t\right)={\dot{V}}_{\mathit{Air}}\times \frac{n\left(t_0\right)}{n\left(t\right)}$

is calculated. The compensated volume flow can then be used to calculate the virtual combustion air ratio.

• bei einer unplausibel großen Abweichung (virtuelles Verbrennungsluftverhältnis deutlich größer/ kleiner als Soll-Verbrennungsluftverhältnis) kann eine Reset-Fahrt des Schrittmotors des Gasventils sinnvoll sein,
• bei einem virtuellen Verbrennungsluftverhältnis deutlich unterhalb des Soll-Verbrennungsluftverhältnis, also einem deutlich zu fetten Verbrennungsgemisch, kann eine entsprechend große Korrektur erfolgen, die das Verbrennungsluftverhältnis möglichst wieder in einen mageren Bereich verschieben kann, und
• bei einer größeren Abweichung des virtuellen Verbrennungsluftverhältnis in Richtung mager kann der zugeführte Volumenstrom Brenngas V̇_Gas in kleinen Schritten erhöht werden. Durch eine Erhöhung in kleinen Schritten kann dabei das Risiko eines Sprunges in einen fetten Bereich gemindert werden.

According to one embodiment, the supplied volume flow of fuel gas V̇ _Gas can be adjusted according to the deviation of the determined R(t) from a target R(t) or the deviation of the determined virtual combustion air ratio from a target combustion air ratio. Depending on the deviation, various case designs are conceivable:

• If the deviation is implausibly large (virtual combustion air ratio significantly larger/smaller than the target combustion air ratio), a reset of the gas valve stepper motor may be useful.
• if the virtual combustion air ratio is significantly below the target combustion air ratio, i.e. if the combustion mixture is significantly too rich, a correspondingly large correction can be made, which can shift the combustion air ratio back into a lean range, if possible, and
• If the virtual combustion air ratio deviates significantly towards lean, the supplied volume flow of fuel gas V̇ _Gas can be increased in small steps. By increasing the volume flow in small steps, the risk of a jump into a rich range can be reduced.

According to one embodiment, if it is determined that the reference range has been left and/or that the limit value has been exceeded or not reached by the virtual combustion air ratio λ _V (t) and/or the ratio R(t), the heater can be (automatically) put into an error state in which commissioning is blocked and which, for safety reasons, can only be ended by a person familiar with the device, such as a service technician.

According to a further embodiment, information about the detection of the virtual combustion air ratio λ _V (t) and/or the ratio R(t) leaving the reference range and/or exceeding or falling below the limit value can be displayed via a display device (external or integrated in 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, information about the detected deviation can advantageously be sent to a user/operator of the heater and/or a specialist company via 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 condition in the heater.

A proposed method thus calculates a virtual combustion air ratio λ _V (t), which enables an estimation and evaluation of the combustion mixture supplied to the burner.

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 heater 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 this. 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 as part of the implementation of a method proposed here can be stored in a memory of the control device, for example a supplied volume flow of combustion air V̇ _Air ( t ₀ ) recorded in step a), a volume flow of combustion air V _Air ( t ) recorded in step c), a ratio R(t) and virtual combustion air ratio λV(t) determined in step d), a reference range and/or limit value.

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. According to one embodiment, the heating device can comprise a flow sensor for detecting the supplied mass or volume flow of combustion air.

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 therein for a more detailed characterisation 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, the heater and the use at least contribute to enabling safe operation of a heater, in particular in the case of a hydrogen-powered heater. A further advantage is that a method proposed here can be carried out entirely using computer implementation and does not require any structural changes to a heater, but can usually be carried out using the existing sensors of the heater.

The method can be particularly advantageously carried out during operation of the heater, for example during an interruption of burner operation, and helps to detect possible critical conditions at an early stage before they can lead to damage to the heater. If necessary, the heater can be automatically taken out of operation if a potentially critical condition is detected.

Fig. 1:

einen Ablauf eines hier vorgeschlagenen Verfahrens,

Fig. 2:

ein hier vorgeschlagenes Heizgerät, und

Fig. 3:

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 attached 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 combine them with other components and findings from the present description. In particular, it should be noted that the figures and in particular the size relationships shown are only schematic. They show:

Fig.1:

a sequence of a procedure proposed here,

Fig. 2:

a heater proposed here, and

Fig. 3:

Parameter curves that can arise when carrying out a procedure proposed here.

Fig.1 shows an example and schematically a sequence of a method proposed here. The execution of steps a), b), c) and d) shown with blocks 110, 120, 130 and 140 can be carried out at least once in the order given in a regular process sequence. The method serves to increase the operational reliability of a heating device 1, in particular one operated with hydrogen or with a hydrogen-containing mixture as fuel. In particular, the specified method can be carried out during operation of the heating device 1 in order to verify/check a combustion air ratio assumed by the combustion control of the heating device 1 and to correct it if necessary.

Fig.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. A volume flow of combustion air V̇ _Air can be sucked in by a conveying device 2, in particular designed as a blower, via a combustion air supply 4, in which a flow sensor 12 can be arranged.

The conveyor device 2 can be connected to a speed controller 6, which can regulate a speed n of the conveyor device 2 by means of a pulse width modulated (PWM) signal. A gas valve 5 can add a volume flow of combustion gas V̇ _Gas from a gas supply 14 to the intake volume flow of combustion air V̇ _Air and can comprise a safety valve and a gas control valve for controlling the volume flow of combustion gas V̇ _Gas to be added. The combustion mixture produced from combustion gas and combustion air can flow to the burner 3 via a mixture channel 11. The burner 3 can have a cylindrical shape. which can be attached with a base to a burner door 15 in such a way that combustion mixture can flow from the mixture channel 11 into the burner 3. After combustion, the combustion products can be discharged to the outside via an exhaust pipe 9 of the heater and an exhaust system 10.

The heating device 1 proposed here can be designed in particular for the combustion of hydrogen. In addition, the heating device 1 can have a (device for) flame monitoring 13 on/or in the burner door 15, which can be designed here as a sensor for UV (ultraviolet) radiation emitted by the flame.

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 speed controller 6, the conveyor device 2, the gas valve 5, the flame monitor 13, the flow sensor 12 and a network 16 (Internet). The control and regulating device 7 can be set up to carry out a method proposed here.

The Fig. 3 and 4 show parameter curves that can be achieved when carrying out a procedure proposed here. Fig.3 shows, by way of example, the curve 20 of the speed n of the conveyor 2 and an analogous curve 21 of an opening position P _GV of the gas valve 5 over time t. As can be seen, in step b) of carrying out a method proposed here, the gas valve 5 is closed at time t=6 seconds and thus the opening position P _GV of the gas valve 5 is set to 0. The first time 18 to can be recorded immediately before the gas valve 5 is closed. In addition,

Fig.4 shows analogous to the Fig.3 given diagram shows a course of the volume flow V̇ combustion air 17. Before closing the gas valve 5 at time t = 6 seconds, the volume flow V̇ combustion air takes a first Value 22, which corresponds to V̇ _Air ( t ₀ ). When the gas valve 5 closes, this increases to a second value 23 V̇ _Air ( t ) at the second time 19. Based on the change in the volume flow V̇, the volume flow of the fuel gas V̇ _Air ( t ₀ ) at the time t0 can be determined according to a method proposed here and a virtual combustion air ratio λ _V (t) can be deduced.

In block 110 according to step a), the volume flow of combustion air V̇ _Air ( t ₀ ) 17 supplied to the burner can be recorded at a first point in time 18 t and stored, for example, in a memory of the control unit 7.

In block 120, the gas valve 5 can be opened or closed according to a step b). This can be done by controlling the gas valve 5 by the regulating and control device 7.

In block 130 according to step c), the volume flow of combustion air 17 can be recorded at the second time V̇ _Air ( t ). The recorded volume flow V̇ _Air ( t ) can be stored in a memory, for example in the control unit 7.

• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t\right)}{{\stackrel{<figure-callout\; id="0"\; label="\; ̇\; Air\; t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">\dot{}</figure-callout>}{V}}_{\mathit{Air}}\left(t_{}\right)\left({}_0\right)}$
  
  , wenn das Gasventil 5 in Schritt b) (Block 120) geöffnet wurde und mit
• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}{{\dot{V}}_{\mathit{Air}}\left(t\right)}$
  
  , wenn das Gasventil 5 in Schritt b) (Block 120) geschlossen wurde.

Das ermittelte Verhältnis R(t) kann gleichfalls auf einem Speicher, beispielsweise des Regel- und Steuergerätes 7, hinterlegt werden.In block 140, according to a step d), a ratio R(t) with

• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t\right)}{{\stackrel{<figure-callout\; id="0"\; label="\; ̇\; Air\; t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">\dot{}</figure-callout>}{V}}_{\mathit{Air}}\left(t_{}\right)\left({}_0\right)}$
  
  if the gas valve 5 was opened in step b) (block 120) and with
• $R\left(t\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}{{\dot{V}}_{\mathit{Air}}\left(t\right)}$
  
  if the gas valve 5 was closed in step b) (block 120).

The determined ratio R(t) can also be stored in a memory, for example in the control unit 7.

erfolgen.In block 150, according to an optional step d), a virtual combustion air ratio λ _V (t) can be calculated by means of ${\mathrm{\lambda }}_V\left(\mathbf{t}\right)=\frac{R\left(t\right)}{A\times \left(1-R\left(t\right)\right)}$

take place.

Now the virtual combustion air ratio λ _V (t) determined in step d) and/or the ratio R(t) determined in step c) can be evaluated in block 150 according to step e). For this purpose, the virtual combustion air ratio λ _V (t) and/or the ratio R(t) can be compared with a limit value or a limit range. If a deviation of the virtual combustion air ratio λ _V (t) from the combustion air ratio assumed by the combustion control is determined, the combustion air ratio can be corrected, for example by adjusting the volume flow of the fuel gas.

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

Speed controller

7

Control and regulation device

8

Combustion chamber

9

Exhaust pipe

10

Exhaust system

11

Mixture channel

12

Flow sensor

13

Flame monitoring

14

Gas supply

15

Burner door

16

network

17

Combustion air flow

18

first point in time to

19

second time t

20

Speed curve

21

Course opening position gas valve P _GV

22

first value

23

second value

Claims (10)

Method for operating a heating device (1), comprising a conveying device (2) for conveying a combustion mixture of fuel gas and combustion air to a burner (3) and a gas valve (5) for controlling a flow rate of fuel gas, the method comprising at least the following steps: a) detecting a volume flow V̇ _Air ( t ₀ ) of combustion air (17) supplied to the burner (3) at a time to(18), b) opening or closing the gas valve (5), c) detecting the volume flow V̇ _Air ( t ) of combustion air (17) at a time t (19) after opening or closing the gas valve in step b), d) Determine a ratio R(t) with - $\mathit{R}\left(\mathit{t}\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t\right)}{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}$

if the gas valve (5) was opened in step b) and with - $\mathit{R}\left(\mathit{t}\right)=\frac{{\dot{V}}_{\mathit{Air}}\left(t_0\right)}{{\dot{V}}_{\mathit{Air}}\left(t\right)}$

if the gas valve (5) was closed in step b). Method according to claim 1, wherein in step e) a virtual combustion air ratio λ _V (t) is calculated by means of ${\mathrm{\lambda }}_V\left(\mathbf{t}\right)=\frac{R\left(t\right)}{A\times \left(1-R\left(t\right)\right)}$

where the factor A represents a minimum air quantity for the combustion of the fuel gas, and an evaluation of the virtual combustion air ratio λ _V (t) is carried out. Method according to claim 1 or 2, wherein in steps a) and c) the volume flow V̇ _Air ( t ₀ ) or V̇ _Air ( t ) is detected using a flow sensor (12). Method according to one of the preceding claims, wherein in steps a) and c) the volume flow V̇ _Air ( t ₀ ) or V̇ _Air ( t ) is determined on the basis of the rotational speed n of the conveying device (2). Method according to one of the preceding claims, wherein the operation of the burner (3) is interrupted and the method is carried out both during the associated closing and opening of the gas valve (5). Method according to one of the preceding claims, wherein when evaluating the ratio R(t) and/or the virtual combustion air ratio λ _V (t) in step e) it is compared with a predetermined reference range and/or a limit value. Method according to claim 6, wherein when the reference range is left or the limit value is exceeded or undershot by the ratio R(t) and/or the virtual combustion air ratio λ _V (t), at least one of the following actions is carried out: - Adjusting the volume flow of fuel gas V̇ _Gas , - decommissioning the heater (1), - Bringing the heater (1) into a fault state in which a new Commissioning is blocked, - Displaying, providing and/or sending information about this. Regulating and control device (7) arranged to carry out a method according to one of claims 1 to 7. Heating device (1), comprising a conveying device (2) and a flow sensor (12) for detecting a supplied volume flow of combustion air V̇ _Air ( t ) (17) and means which are adapted to carry out a method according to one of claims 1 to 7. Computer program comprising instructions which cause a heating device (1) according to claim 9 to carry out the method steps of a method according to one of claims 1 to 7.

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