Method for operating a heating device, computer program and heating device

Abstract

A method for operating a heating appliance (1) is proposed, 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) comprising an offset setting (24) for controlling a fuel gas flow rate with an actuator (25) for actuating the offset setting (24), wherein the method comprises at least the following steps: a) initiating a commissioning of the heating appliance (1), b) determining a virtual combustion air ratio λv(t) during commissioning in step a), c) determining a difference (28) between the virtual combustion air ratio λv(t) determined in step b) and a predetermined combustion air ratio λZ, d) determining a dynamic offset value (29) and a corresponding control signal for the actuator (25) of the offset setting (24) of the gas valve (5).in the application of which the difference (28) determined in step c) is compensated, and e) actuation of the actuator (25) of the offset setting (24) of the gas valve (5) with the control signal from step d).,

Description

[0001] The invention relates to a method for operating a heating device, a computer program and a heating device.

[0002] When a heating appliance is commissioned, a delivery system is typically brought up to a starting power level. Once this level is reached, a gas valve opens, adding a mass flow of fuel gas corresponding to the starting power level or a starting mass flow of combustion air and a starting combustion air ratio. This also activates an ignition device. Often, during the ignition process, the combustion mixture is continuously enriched according to an ignition ramp, meaning the proportion of fuel gas in the mixture is increased, which reduces the combustion air ratio. After a flame is detected by a flame monitor, the opening position of the gas valve is usually changed by a fixed offset value, and the heating appliance or burner switches to normal operation. Such a commissioning procedure is described in DE 10 2006 006 964 A1.At the moment of ignition, an air-fuel ratio is calculated from the burner temperature using a characteristic curve, and a new starting combustion air ratio is set. However, the process is complex and not very precise.

[0003] DE 10 2022 133 191 A1 describes a method for commissioning a heating appliance in which a virtual combustion air ratio is calculated. However, this method is not applicable to a heating appliance with a pneumatic gas-air system.

[0004] During operation of the heating appliance, various tolerances, such as varying gas quality, manufacturing tolerances of the gas valve, or fluctuating environmental conditions (temperature, humidity), can cause deviations between the actual combustion air ratio and the specified combustion air ratio. These deviations reduce combustion efficiency and can also promote critical conditions such as flame flashback. This is particularly true for heating appliances with a pneumatic gas-air system where the supplied gas quantity is linked to a pressure drop at a throttling point, making correction of the air ratio virtually impossible. Heating appliances operating with hydrogen-containing fuel gas are even more susceptible to these problems, as hydrogen has significantly different combustion properties.

[0005] Based on this, the object of the invention is to propose a method for operating a heating device, a computer program, and a heating device that at least partially overcome the problems of the prior art described above. In particular, the invention is intended to enable the stable and safe operation of a heating device, especially a heating device with a pneumatic gas-air system.

[0006] Furthermore, the process should be suitable for at least partial automation and require as few structural changes as possible compared to a state-of-the-art heating device.

[0007] These problems are solved by the features of the independent claims. Further advantageous embodiments of the solution proposed here are specified in the independent claims. It should be noted that the features listed in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0008] This involves a method for operating a heating appliance. The heating appliance has a conveying device for supplying a combustion mixture of fuel gas and combustion air to a burner and a gas valve. The gas valve includes an offset adjustment for controlling the fuel gas flow rate, which has an actuator for operating the offset adjustment. The method comprises at least the following steps: a) Initiating the commissioning of the heating appliance, b) Determining a virtual combustion air ratio λ V (t) during commissioning in step a), c) Determining a difference between the virtual combustion air ratio λ V (t) determined in step b) and a predetermined combustion air ratio λ Z, d) Determining a dynamic offset value based on the difference determined in step c) which minimizes or compensates for the difference determined in step c), and e) Actuating the offset setting of the gas valve by the dynamic offset value determined in step d).

[0009] Steps a), b), c), d), and e) can be performed at least once in the specified order. The procedure can be carried out, in particular, each time the heating appliance is started up. Step e) can be performed, in particular, immediately after a flame is detected and can mark the transition from ignition mode to regular operation of the heating appliance. The procedure serves, in particular, to refine the combustion control of a heating appliance, especially one with a pneumatic gas-air mixture, by compensating for the effects of tolerances in the heating appliance components or the quality of the supplied fuel gas and / or the effects of changing ambient conditions, especially the pressure, temperature, and humidity of the supplied combustion air.

[0010] The heating appliance can include at least one heat generator, in particular a gas condensing boiler, which releases thermal energy by burning a fuel and can transfer it to a heating circuit via at least one heat exchanger, with consumers of the heating circuit being connectable to the heating appliance via a flow and a return line. The exhaust gases produced during combustion can be routed to an exhaust system via an exhaust duct of the heating appliance. Butter A heating appliance can be equipped with a circulation pump in the heating circuit to circulate a heat transfer medium (heating water), whereby the heated heat transfer medium can be supplied to consumers, such as convectors or underfloor heating systems, via a heating flow and returned to the heat generator or the at least one heat exchanger via a heating return.

[0011] For this purpose, the heating appliance can have a conveying device, in particular a blower, which can supply a mixture of combustion air and fuel gas to a burner of the heating appliance located in a combustion chamber. Combustion air can refer to the airflow conveyed by the conveying device, regardless of whether it is actually used for combustion or is conveyed, for example, during commissioning, when starting up the conveying device, or during purging processes. The conveying device can include a power control, in particular a speed controller. Alternatively, the heating appliance can have an electronic gas-air mixture in which a signal from a flame monitor allows conclusions to be drawn about the flames and the

[0012] The combustion air-fuel ratio (also known as lambda or air-fuel ratio) can be adjusted, allowing for its control. The heating appliance can be specifically designed for the combustion of hydrogen as fuel or a (fuel) mixture containing hydrogen. The mixture can have a hydrogen content of at least 80% or at least 90%.

[0013] The gas valve includes an offset adjustment, also known as zero-point shift. This offset adjustment can be actuated by an actuator. The actuator could, for example, be a stepper motor that operates a rotary adjustment mechanism (adjusting screw) on the gas valve. The actuator is electrically controlled and connected, for instance, to a control unit of the heating appliance in such a way that a control signal can be transmitted to the actuator, which then automatically adjusts the gas valve's offset accordingly. In particular, this actuator could be the one used to regulate the air-fuel ratio during operation of the heating appliance.

[0014] Furthermore, the heating appliance may feature flame monitoring. This often involves the use of an ionization electrode, which utilizes the flame's ionization current to detect its presence. However, this principle is not reliably applicable to hydrogen flames, as the combustion of hydrogen produces significantly fewer free charge carriers. Therefore, hydrogen-powered heating appliances frequently employ other methods, such as detecting the electromagnetic radiation emitted by the flame, particularly infrared (IR) and / or ultraviolet (UV) radiation, or measuring the flame temperature. A signal from flame monitoring can indicate the presence of a flame and provide information about the flame's air-fuel ratio.

[0015] According to step a), the heating appliance can be initiated. This can be triggered, for example, by a heat demand on the heating appliance, which can occur when a hot water outlet or a thermostatic valve of a consumer (radiator or underfloor heating) is opened.

[0016] The commissioning of a heating appliance can proceed as follows. First, a control unit of the heating appliance, for example, can start a conveying device, which is usually a blower, up to a predetermined starting power or starting speed. After reaching the predetermined starting power or starting speed, a purging phase of a predetermined duration can follow, in which any combustion gas present in the combustion chamber from a previous, possibly unsuccessful, start-up is purged. At the predetermined starting power or starting speed, a starting volume flow of combustion air is established. V̇ Air ( t0) one. Now, a predetermined fuel flow rate (starting mass flow or starting volume flow of fuel) for the starting power or starting speed can be supplied by moving the gas valve to the corresponding opening position. Step b) can then be carried out. With the opening of the gas valve and the supply of fuel gas, an ignition device can be activated. With increasing fuel gas volume flow... V̇ Gas The volume flow of combustion air can decrease continuously over time t according to an ignition ramp, and the volume flow of fuel gas can decrease inversely proportionally. V̇ GasThe temperature increases until the combustion mixture in the combustion chamber ignites and forms a (stable) flame. This flame can be detected by a flame monitoring device. Subsequently, a conventional heating appliance would perform a static offset adjustment, i.e., apply a fixed (static) offset value. The invention involves replacing this static offset value of the gas valve with a dynamically determined offset value, calculated using sensors. The dynamic offset value is designed to compensate for the influence of tolerances and environmental factors on the combustion control. The described commissioning process of a heating appliance can be carried out, in particular, by a control unit of the heating appliance. Typically, a safety period, often legally mandated, is measured from the opening of the gas valve.If the flame monitoring system fails to detect a flame within the specified safety period, the start-up process is aborted and the gas valve is closed to prevent the release of a large amount of unburned gas. If necessary, another start-up attempt may be made, followed by a purging cycle. Once a flame is detected, the heater will transition to normal operation, possibly after a stabilization period, and may switch from the combustion air ratio of the ignition phase to that of normal operation.

[0017] According to step b), a virtual air-fuel ratio λV(t) can be determined during commissioning in step a). The virtual air-fuel ratio λV(t) is a calculated air-fuel ratio determined using at least one measured parameter, which can be determined after the gas valve is opened. This can be done, for example, with a suitable sensor, such as a gas mixture sensor or a gas flow sensor. The virtual air-fuel ratio can thus be understood as an actual air-fuel ratio, which is calculated, if necessary, by including a signal from at least one sensor after the gas valve has opened.

[0018] According to one embodiment, the virtual combustion air ratio λ V (t) can be determined using a method comprising at least the following steps: a1) Capturing a volume flow of combustion air supplied to the burner V̇ Air ( t 0) before the gas valve of the heating appliance opens at time t 0 , b1) measuring the volume flow of combustion air V Air ( t ) after opening the gas valve at time t, c1) Determining a ratio R(t) with R t = V ˙ Air t V ˙ Air t 0 , and d1) Calculate a virtual combustion air ratio λ V (t) by means of λ V t = R t A × 1 − R t , where factor A represents a minimum amount of air for the combustion of the fuel gas.

[0019] According to step a1), a detection of a volume flow of combustion air supplied to the burner is possible V̇ Air ( t0) at a time t 0 before the opening of a gas valve of the heating appliance. The supplied combustion air volume flow corresponds in particular to the combustion air volume flow delivered at the starting power or starting speed of the conveying device. In this context, the combustion air volume flow can also be understood as the conveying volume flow of the conveying device.

[0020] In particular, the measured volume flow of combustion air V̇ Air ( t 0 ) are stored on an electronic data storage device, for example, a memory of the control and regulating unit.

[0021] According to step b1), the volume flow of combustion air can be measured. V Air ( t ) during or after the opening of the gas valve at a time t. Time t can be a predetermined period after time t0. In particular, the measurement of the combustion air volume flow can be carried out. V Air ( t The measurements are performed continuously or over a predetermined recording period, whereby the recording period is at least partially parallel to the opening process of the gas valve and / or the fully open gas valve. Typically, time t is used to calculate the virtual air-fuel ratio λ. V (t) should be selected such that the flow of the combustion mixture and the resulting air-fuel ratio have stabilized. Time t should be characterized, in particular, by a gas mass flow rate that is as constant as possible. The exact time may also depend on the geometry of the gas-air mixture. In any case, time t should occur before the actual ignition of the combustion mixture. For example, a time t in the range of 200 milliseconds to 400 milliseconds, and especially 250 milliseconds to 350 milliseconds, may be suitable. A suitable time t can also be determined by experiments on a reference heater.

[0022] According to one embodiment, the volume flow of combustion air can be measured. V̇ Air ( t 0 ) and / or the volume flow of combustion air V Air ( t) by means of a flow sensor (a mass flow or volume flow sensor) which may be located in a combustion air supply of the heating device, for example in a silencer of a combustion air supply.

[0023] In this context, it should be noted that a (gaseous) volumetric flow rate can be easily converted into a mass flow rate and vice versa. This can be approximated by multiplication using a conversion factor or by a precise conversion based on knowledge of the state parameters of the gas flow being measured, in particular its density, temperature, and pressure. Therefore, any reference to a mass flow rate within this document can always be understood as a reference to a volumetric flow rate, and vice versa.

[0024] According to step c1), a ratio R(t) can be determined: R t = V ˙ Air t V ˙ Air t 0 . The ratio is derived from the fact that the volume flow rate delivered by the conveying device at a constant rotational speed is constant (independent of density) and the volume flow rate of fuel gas V̇ Gas ( t ) thus by means of V ˙ Gas t = V ˙ Air t 0 − V ˙ Air t can be derived.

[0025] Based on the ratio R(t) determined in step c1), a conclusion can be drawn about the combustion air ratio at time t. For this purpose, the determined R(t) can, for example, be compared with a given reference range of R(t) and the combustion at time t can be evaluated.

[0026] Now, in step d1), a virtual combustion air ratio λ V (t) can be calculated using λ V t = R t A × 1 − R t take place.

[0027] 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 needed 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 be calculated. For example, factor A (the minimum air requirement for combustion) is 2.381 for 100% hydrogen, 9.52 for 100% methane, 23.8 for 100% propane, and 31 for 100% butane. Factor A (the minimum air requirement) can be stored, for example, in the control unit of the heating appliance, perhaps as an average value for the gases within a gas family.

[0028] Alternatively, the minimum air requirement A could also be determined, for example, from a commissioning procedure and / or with the help of other control loops of the heating appliance. For this purpose, a lambda control loop of a heating appliance can be used, which can regulate the combustion air ratio of the heating appliance independently of the gas type during operation. Thus, after the gas valve is closed with R t = Vm ⋅ Air t 0 V ˙ Air t and λ V t = R t A × 1 − R t The minimum air requirement A can be determined with knowledge of the combustion air ratio during operation.

[0029] An alternative approach could involve reducing the air-fuel ratio from a non-ignitable range (thus increasing the fuel-air ratio in the combustion mixture) until successful ignition occurs, thereby determining an R(t) value for the leanest ignitable mixture. Knowing the lambda limit of the device for ignition (i.e., the maximum lambda (air-fuel ratio) at which ignition is possible), the minimum air requirement A could be calculated using the determined R(t).

[0030] According to one embodiment, in step e1) an evaluation of the virtual air-fuel ratio λV(t) could be performed. This evaluation is carried out particularly with regard to identifying a critical commissioning phase and utilizes the virtual air-fuel ratio λV(t) and / or a gradient of the virtual air-fuel ratio λV(t). The gradient G(t) of the virtual air-fuel ratio λV(t) can be the slope of the virtual air-fuel ratio λV(t) determined by a mathematical derivation.

[0031] According to one embodiment, the evaluation according to step e1) could take into account the fact that a virtual air-fuel ratio λV(t) that is too low may indicate potentially critical conditions of the heating appliance. Therefore, terminating an ignition process if the virtual air-fuel ratio λV(t) is too low could be considered. Conversely, a virtual air-fuel ratio λV(t) that is too high is unlikely to lead to critical conditions, and termination for safety reasons is not necessary; the ignition attempt can continue until it is completed (by the end of the safety time or by flame formation).

[0032] According to one embodiment, during step e1), the virtual air-fuel ratio λV(t) or the gradient G(t) determined in step d1) can be compared with a (respective) reference range. A deviation from the reference range can indicate a critical condition during commissioning, in particular a critical air-fuel ratio λ. The reference range can be defined by an upper and a lower limit, whereby a virtual air-fuel ratio λV(t) greater than the upper limit and / or less than the lower limit can indicate a potentially critical condition during commissioning, especially in connection with delayed ignition. Conversely, a combustion-fuel ratio that is too low results in a lower flame speed and lower power output, and can thus lead to slowed or even no flame formation during ignition.The reference range can also be a limit value, the exceeding or falling below of which can indicate a critical condition. In particular, falling below the limit value can be critical, as this can indicate a low λ and thus a high proportion of fuel in the combustion mixture (rich mixture).

[0033] According to one embodiment, the reference range and / or limit value may have been determined in advance on a reference heating device in (laboratory) tests and stored on a memory of the heating device, in particular a control and regulating device of the heating device.

[0034] According to one embodiment, if the reference range is exceeded or not exceeded by the virtual combustion air ratio λ V (t) and / or the ratio R(t) in step e), the volume flow of fuel gas can be adjusted. V̇ Gas be adapted.

[0035] According to one embodiment, if the virtual combustion air ratio λV(t) and / or the ratio R(t) in step e1) are detected as having been deviated from the reference range and / or exceeding or falling below the limit value, particularly if the virtual combustion air ratio λV(t) is below a reference range or limit value, the ignition process can be aborted. Subsequently, a restart attempt could be made with an adjusted fuel gas volume flow rate. V̇ Gas This will take place, in which, in particular, a procedure proposed here can be carried out again.

[0036] As described, a constant speed of the conveying device is crucial for determining R(t) or the virtual combustion air ratio λV(t). However, a brief speed deviation can occur when the gas valve opens or closes. According to one embodiment, this speed deviation can be compensated for by additionally recording the speed n of the conveying device at time t0 and time t and calculating a compensated volume flow rate. V ˙ Air Komp t = V ˙ Air × n t 0 n t The compensated volume flow rate can then be used to calculate the virtual combustion air ratio.

[0037] According to one embodiment, the supplied volume flow of fuel gas can be adjusted, particularly during a renewed attempt at commissioning. V̇ GasThe values ​​are adjusted according to the deviation of the determined R(t) from a target R(t) or the deviation of the determined virtual air-fuel ratio from a target air-fuel ratio. Depending on the deviation, various scenarios are conceivable: In the case of an implausibly large deviation (virtual air-fuel ratio significantly larger / smaller than the target air-fuel ratio), a reset of the gas valve's stepper motor may be advisable. If the virtual air-fuel ratio is significantly below the target air-fuel ratio, i.e., a significantly too rich combustion mixture, a correspondingly large correction can be made to shift the air-fuel ratio back into a leaner range. And if the virtual air-fuel ratio deviates significantly towards a leaner mixture, the supplied fuel gas volume flow can be adjusted in small increments. V̇ GasThe amount of fuel supplied can be increased. Increasing it in small increments can reduce the risk of over-fueling. An increase in the fuel gas flow rate could also be considered. V̇ Gas depend on a plausibility check of the virtual combustion air ratio.

[0038] According to one embodiment, the ignition process can be adapted to the deviation of the determined R(t) from a target R(t) or the deviation of the determined virtual air-fuel ratio from a target air-fuel ratio. This adaptation of the ignition process can particularly affect the safety time and the ignition power (ignition intensity). For example, the safety time can be shortened if the air-fuel ratio is less than one. For instance, if the air-fuel ratio is 0.7, the safety time could also be shortened by a factor of 0.7.

[0039] Alternatively or cumulatively, a power factor can also be determined, which can be used to adjust the ignition process. The power factor can be derived from Q Soll Q λ _ Virt = 1 + A × λ Virt 1 + A × λ Soll The power factor can be used to determine a reduction factor for the safety time, whereby a constant amount of energy per ignition attempt can be decisive for the reduction. The power factor can also be used to determine a necessary change in power for a subsequent ignition attempt.

[0040] According to a further specification, if a predetermined maximum number of commissioning attempts of the heating appliance is reached and a deviation from the reference range or an exceedance or fall below the limit value is detected, the commissioning of the heating appliance can be aborted. The predetermined maximum number of commissioning attempts will typically range from 2 to 10 attempts, particularly from 4 to 6 attempts. Often, country-specific regulations or standards further restrict the number of commissioning attempts.

[0041] According to one design, after the maximum number of commissioning attempts has been unsuccessful, the heating device can be (automatically) put into a fault state which, for safety reasons, can only be terminated by a person familiar with the device, such as a service technician.

[0042] In a further embodiment, information indicating that the maximum number of commissioning attempts has been reached can be displayed via an (external or integrated) display device and / or made available for retrieval via a network, particularly the internet, and / or sent as a message. For example, the information can be made available on an appliance interface of the heating device or on network storage (cloud). This allows, for instance, a user / operator of the heating device and / or a service company to be notified of a commissioning error via a message, enabling the service company to schedule and carry out a maintenance and / or repair appointment accordingly. In particular, this facilitates a rapid resolution of a fault condition affecting the heating device.

[0043] According to step c), a difference can be determined between the virtual air-fuel ratio λV(t) determined in step b) and a predetermined air-fuel ratio λZ for ignition operation. The predetermined air-fuel ratio λZ can thus also be understood as the target or setpoint air-fuel ratio for ignition operation and corresponds to the air-fuel ratio assumed or anticipated by the control system for the ignition operation at time t for which the virtual air-fuel ratio λV(t) was determined in step b). The predetermined air-fuel ratio λZ can, for example, correspond to a position or time on an ignition ramp of the air-fuel ratio for ignition operation. If necessary, the predetermined air-fuel ratio λZ can also lie outside the ignition ramp.The difference, as a deviation of the measured (virtual) combustion air ratio from a predetermined target or specified combustion air ratio λZ, can be caused by tolerances, fluctuations in gas quality, or ambient conditions. The target combustion air ratio λZ can be stored for each operating point, for example, as a characteristic curve on a memory, such as the memory of a process control unit.

[0044] According to step d), a dynamic offset value and a corresponding control signal for the actuator of the gas valve's offset setting can be determined. This signal compensates for the difference determined in step c). The determination is performed computationally or by applying a predefined characteristic curve. This curve assigns a change in the offset value, and thus the dynamic offset value, to a known desired change in the amount of gas to be supplied (and therefore the resulting combustion air ratio, such as the difference from step d). A control signal for the gas valve actuator can then be determined for this dynamic offset value. The relationship between the gas valve's offset setting and the resulting pressure change, and thus the change in the amount of gas supplied, is generally known according to the predefined characteristic curve.Alternatively or cumulatively, this relationship may also have been determined in advance using a reference gas valve as part of experiments.

[0045] According to step e), the actuator for the offset setting of the gas valve can now be actuated using the control signal from step d).

[0046] After completing step e), the heating appliance can now be operated, whereby deviations in the combustion air ratio due to the influence of tolerances of components of the heating appliance or the gas valve, the exhaust system and / or the gas quality or environmental influences (for example, pressure, temperature and humidity of the supplied combustion air) are compensated by adjusting the offset setting in step e).

[0047] Another aspect is the proposal for a heating appliance. This heating appliance could be a gas-fired appliance, for example, a hydrogen-powered one. The gas-fired appliance could include a burner and a delivery system for supplying a mixture of fuel gas and combustion air to the burner. Specifically, the heating appliance could generate a pneumatic gas-air mixture and include a gas valve that is controlled by a pressure applied by a throttling device, such as a Venturi nozzle, in the combustion air supply. The gas valve includes an offset adjustment mechanism that is operatively connected to an actuator and can be actuated by it. The heating appliance could also include a control unit that is electrically connected to the actuator in such a way that the actuator is controlled by the control unit, thus establishing a calculated or determined offset setting.The same can be changed by the actuator on the gas valve.

[0048] The control unit of the heating appliance can be configured to carry out one of the procedures proposed here. For this purpose, the control unit can, for example, include and / or have a processor. In this context, the processor can, for example, execute the procedure stored in a memory (of the control unit). The control unit can be electrically connected to a conveying device, an actuator for the offset adjustment of the gas valve, and / or a flame monitoring system. Furthermore, data acquired or required during the execution of one of the procedures proposed here, such as characteristic curves, limit values, etc., can be stored in a memory of the control unit.

[0049] In addition, a computer program (product) is proposed that is designed to (at least partially) execute the procedure presented here. In other words, this specifically concerns a computer program (product) comprising instructions that, when executed by a computer, cause it to carry out the procedure proposed here. The computer program can, in particular, be executed on a control unit of the heating device.

[0050] Another aspect that is proposed is a machine-readable storage medium on which the computer program is stored.

[0051] The machine-readable storage medium is usually a computer-readable data carrier.

[0052] The details, features, and advantageous designs discussed in connection with the process may also occur in the computer program and heating device presented here, and vice versa. In this respect, full reference is made to the explanations provided therein for a more detailed characterization of the features.

[0053] This document presents a method for operating a heating device, a computer program, and a heating device that at least partially solve the problems described with reference to the prior art. In particular, the method for operating the heating device, the computer program, and the heating device contribute to enabling the safe operation of a heating device, especially a hydrogen-powered heating device and / or a heating device with a pneumatic gas-air system. Furthermore, the method proposed here is advantageously fully computer-implemented and therefore requires no structural modifications to the heating device.

[0054] This method is particularly advantageous because it can be carried out every time the heating appliance is started up, thus enabling subsequent operation of the appliance with a combustion air ratio that closely matches a predetermined target combustion air ratio. This effectively prevents unsafe operating conditions such as flame flashback.

[0055] Furthermore, the invention advantageously requires only minor or no structural modifications to a heating device and can often be implemented within the framework of a software implementation.

[0056] The invention and its technical context 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 shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1 : a sequence of a procedure proposed here, Fig. 2 : a heating device suggested here, Fig. 3 : Parameter profiles that can occur when carrying out a procedure proposed here Fig. 4a ) and b) parameter profiles during the commissioning of a heating appliance according to the state of the art, and Fig. 5a) and b) parameter profiles during the commissioning of a heating device proposed here.

[0057] Fig. 1 Figure 1 shows an exemplary and schematic representation of the sequence of a procedure proposed here. Steps a), b), c), d), and e), represented by blocks 110, 120, 130, 140, and 150, can be carried out at least once in the specified order during a regular procedure. The procedure can be performed during commissioning and, in particular, during every commissioning of a heating appliance 1. The procedure serves to increase the operational reliability of a heating appliance 1, especially one operated with hydrogen or a hydrogen-containing mixture as fuel.

[0058] Fig. 2Figure 1 shows an exemplary and schematic representation of a heating device 1 proposed here. This device can include a burner 3 arranged in a combustion chamber 8. A combustion air supply 4, in which a mass flow sensor 12 can be arranged, can be used to measure the volume flow of combustion air. V̇ Air The combustion air is drawn in by a conveying device 2, in particular designed as a blower. A mass flow of combustion air is detected by the mass flow sensor 12. Air can simply be fed into a volume flow of combustion air V̇ Air The conveying device 2 can be connected to a speed controller 6, which can regulate the speed n of the conveying device 2 by means of a pulse-width modulated (PWM) signal. A gas valve 5 can supply combustion air to the aspirated volume flow. V̇ Air a volume flow of fuel gas V̇ Gas from a gas supply 14 and a safety valve as well as a gas control valve for controlling the volume flow of fuel gas to be added V̇ Gas The gas valve 5 also includes an offset adjustment 24, which is operatively connected to and can be actuated by an actuator 25. The generated combustion mixture of fuel gas and combustion air can flow to the burner 3 via a mixture channel 11. The burner 3 can have a cylindrical shape, the base of which can be attached to a burner door 15 in such a way that the 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 heating appliance and an exhaust system 10.

[0059] The heating device 1 proposed here can be configured specifically for the combustion of hydrogen. Furthermore, the heating device 1 can have a flame monitoring device 13 on / in the burner door 15, which can be designed as a sensor for UV (ultraviolet) radiation emitted by the flame.

[0060] A control unit 7 can be configured to control the heating appliance 1. For this purpose, it can be electrically connected, for example, to the speed controller 6, the conveying device 2, the gas valve 5, the actuator 25, the flame monitoring device 13, the mass flow sensor 12, and a network 16 (Internet). The control unit 7 can be configured to carry out a procedure proposed herein. For this purpose, the control unit can include a memory containing a computer program 23 that causes the control unit 7 to execute a procedure according to blocks 110, 120, 130, 140, and 150.

[0061] In block 110, according to step a), the commissioning of heating device 1 can be initiated, i.e., a start or ignition process can be started. This can be triggered, for example, by a heat demand on heating device 1.

[0062] In block 120, a virtual combustion air ratio λ V (t) can be determined during the commissioning initiated in step a) according to step b).

[0063] The Fig. 3 and 4 The parameter profiles shown are those that can occur when determining the virtual combustion air ratio λV(t) during the implementation of a method proposed here. A volume flow of combustion air is used. V Air ( t ) 17 and a volume flow of fuel gas V̇ Gas ( t Figure 18 shows the function of the heating unit 1 as a function of time t during commissioning. Initially, a starting power or starting speed of the conveying device 2 was established, resulting in a constant volume flow of combustion air. V̇ Air ( t can set 0 ) 21.

[0064] In block 210 and according to step a1), the volume flow of combustion air supplied to burner 3 can be V̇ Air ( t0) 21 before the gas valve 5 opens, at a first time t 0 19, the mass flow sensor 12 detects the value and stores it, for example, in a memory of the control unit 7. Following the first time t 0 19, the gas valve 5 opens, whereby the gas control valve introduces a starting volume flow of fuel gas 22, corresponding to a control pressure of a throttle point (not shown here) that is controlled by the starting volume flow of combustion air. V̇ Air ( t 0 ) 21 is flowed through.

[0065] In block 220, according to step b1), the volume flow of combustion air can now be continuously increased. V Air ( t ) 21 are recorded. By opening the gas valve 5, the fuel gas volume flow 18 increases to the starting fuel gas volume flow 22, while at the same time the combustion air volume flow V Air ( t) 17 decreases by the amount of the volume flow of fuel gas 18, so that at constant speed of the conveying device (2) a constant volume flow of combustion mixture results at every point in time during the formation of the combustion mixture.

[0066] In block 230, according to step c1), a ratio R(t) can be determined with, and R t = V ˙ Air t V ˙ Air t 0 .

[0067] In block 240, according to step d1), a virtual combustion air ratio λ V (t) can be calculated with λ V t = R t A × 1 − R t take place.

[0068] According to an optional step e1), not shown here, the virtual air-fuel ratio λV(t) determined in block 240 (step d1)) can be evaluated. In particular, the virtual air-fuel ratio λV(t) can be compared with a limit value. In this case, the limit value was undershot by the virtual air-fuel ratio λV(t) at a second time point 20, which can indicate an insufficient virtual air-fuel ratio λV(t) and thus an excessively high proportion of fuel gas in the combustion mixture, which can be associated with a high risk of ignition problems, such as flame flashback. Due to the limit value being undershot, the start-up attempt is aborted at the second time point 20 and the gas valve 5 is closed, thereby reducing the fuel gas volume flow. V̇ Gas ( t ) 18 returns to zero and the volume flow of combustion air V Air ( t) 17 can rise again to the combustion air volume flow 21.

[0069] Fig. 4a) and 4b Figures ) show diagrams of the combustion air ratio λ over time t during the commissioning of a heating appliance according to the state of the art. The target combustion air ratio for normal operation 26 indicates the setpoint combustion air ratio that should be adjusted after a successful ignition process. The Fig. 4a ) an ignition process with a combustion air ratio that is too lean due to tolerances (ignition operation 31). After a flame is detected at a third time point 30, a static offset value 27 is applied to the gas valve 5 and the heating appliance 1 is operated in normal operation. A difference 28 remains between the actually set combustion air ratio (normal operation 32) and the target combustion air ratio (normal operation 26), which is undesirable and, depending on the size of the difference 28, can lead to unsafe operating conditions. Fig. 4b ) shows analogous to Fig. 4a ) an ignition process with a combustion mixture that is too rich due to tolerances.

[0070] Fig. 5a) and 5b ) show the diagrams according to Fig. 4a) and 4b ) with a heating device 1 proposed here, which performs a method proposed here. The following also shows Fig. 5a ) an ignition process with a combustion air ratio that is too lean due to tolerances and the Fig. 5b) with a combustion air ratio that is too rich due to tolerances, recognizable by the (actual) combustion air ratio during ignition operation 31. By carrying out a procedure proposed here, a dynamic offset value 29 is determined and set at the offset setting 24 of the gas valve 5 by the actuator 25. This causes the actual combustion air ratio during normal operation 32 to align with the target combustion air ratio 26 and a difference 28 no longer occurs. Advantageously, this can significantly increase the operational reliability when operating the heating appliance 1, since the control system can set a precise combustion air ratio and the probability of flame flashbacks can be considerably reduced.

[0071] It should be noted as a precaution that the numerical terms used here ("first", "second", etc.) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described. Where a component can occur multiple times ("at least one"), the description of one of these components may apply equally to all or some of the multiple components, but this is not mandatory. Reference symbol list

[0072] 1 Heater 2 Conveyor 3 Burner 4 Combustion air supply 5 Gas valve 6 Speed ​​controller 7 Control unit 8 Combustion chamber 9 Exhaust pipe 10 Exhaust system 11 Mixture channel 12 Mass flow sensor 13 Flame monitoring 14 Gas supply 15 Burner door 16 Network 17 Combustion air flow rate 18 Fuel gas flow rate 19 First time point 20 Second time point 21 Combustion air flow rate before gas valve opening 22 Fuel gas flow rate before gas valve opening 23 Computer program 24 Offset setting 25 Actuator 26 Target combustion air ratio, normal operation 27 Static offset value 28 Difference 29 Dynamic offset value 30 Third time point 31 Combustion air ratio, ignition operation 32 Combustion air ratio, normal operation

Claims

1. A method for operating a heating appliance (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) with an offset setting (24) for controlling a fuel gas flow rate, which has an actuator (25) for actuating the offset setting (24), wherein the method comprises at least the following steps: a) initiating the commissioning of the heating appliance (1), b) determining a virtual combustion air ratio λ V (t) during commissioning in step a), c) Determining a difference (28) between the virtual air-fuel ratio λ determined in step b). V (t) and a given combustion air ratio λ Z, d) Determining a dynamic offset value (29) and a corresponding control signal for the actuator (25) of the offset setting (24) of the gas valve (5), the application of which compensates for the difference (28) determined in step c), and e) Actuating the actuator (25) of the offset setting (24) of the gas valve (5) with the control signal from step d).

2. The method of claim 1, wherein the virtual combustion air ratio λ V (t) during commissioning in step a) is determined as follows: a1) Determining a volume flow of combustion air supplied to the burner (3) V̇ Air ( t 0) (17) before opening the gas valve (5) of the heating appliance (1) at time t0 , b1) measuring the volume flow of combustion air V Air ( t ) (17) after opening the gas valve (5) at time t, c1) Determining a ratio R(t) with R t = V ˙ Air t V ˙ Air t 0 , d1) Calculating a virtual combustion air ratio λV (t) by means of λ V t = R t A × 1 − R t , where factor A represents a minimum amount of air for the combustion of the fuel gas.

3. Method according to one of the preceding claims, wherein, after an unsuccessful or aborted start-up of the heating device (1) in step a), the volume flow of fuel gas is increased during a subsequent start-up. V̇ Gas (18) and / or the offset setting (24) is adjusted to set a starting combustion air ratio.

4. Heating device (1) comprising a conveying device (2) for conveying a combustion mixture of fuel gas and combustion air to a burner (3), a gas valve (5) with an offset setting (24) for controlling a flow rate of fuel gas, an electrically controllable actuator (25) for actuating the offset setting (24) of the gas valve (5) and a control and regulating device (7), configured for carrying out a method according to one of the preceding claims.

5. Computer program (23) comprising commands that cause a heating device (1) according to claim 4 to perform the process steps of a method according to any one of claims 1 to 3.

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