EP4060232B1 - Power detection and air/fuel ratio control by means of sensors in the combustion chamber - Google Patents

Description

background

The present disclosure relates to controls and/or regulation as used in combustion devices, such as gas burners, in connection with combustion sensors. Combustion sensors in combustion devices are, for example, ionization electrodes and/or optical sensors. In particular, the present disclosure relates to the regulation and/or control of combustion devices in the presence of hydrogen gas.

When a combustion device is in operation, its combustion output must be known and/or set. For combustion of hydrocarbons or of pure hydrogen or a mixture of both, the air supply and the fuel supply must be adjusted to each other. A correct air ratio λ is thus achieved.

In addition, external influences can affect the air ratio and/or the combustion output. Such external influences are, for example, the inlet pressure of the fuel, in particular the fuel gas, and the fuel composition. Further examples of external influences are the ambient temperature, the ambient pressure and changes in the air supply path and in the exhaust gas path of the combustion device.

In addition to the sensors mentioned, such sensors which monitor the flame in a safety-related manner can be included in the control of the combustion output and/or the air ratio of a combustion device.

Optical flame monitoring has hitherto been used for the combustion of pure hydrogen in a combustion device. Meanwhile, optical sensors for recording signals during combustion are expensive.

Furthermore, thermocouples and/or resistance temperature sensors are conceivable as sensors for recording combustion signals. Thermocouples and/or resistance temperature sensors are to be thermally coupled to the supply air and/or the mixture and/or the exhaust gas and/or the plasma of a combustion at a combustion device. Thermocouples and/or resistance temperature sensors are also thermally coupled to the mechanical mount. As a result of such couplings, thermocouples and/or resistance temperature sensors have hitherto tended to be too slow for monitoring a combustion process.

In particular, such elements and sensors for monitoring a flame in a combustion device tend to be slow.

A European patent application EP1154202A2 was filed on April 27, 2001 by SIEMENS BUILDING TECH AG. The application was published on November 14, 2001. EP1154202A2 deals with a control device for a burner. EP1154202A2 takes a priority from May 12, 2000 claim. To EP1154202A2 is a granted European patent EP1154202B1 before. There is also a patent EP1154202B2 after an appeals process.

EP1154202B2 distinguishes between fuel gases with a low and high calorific value. Two characteristic curves are used to differentiate between the two fuel gases. The two characteristic curves each relate to a control signal for an actuator of the combustion device over a fan speed of the combustion device. Control signals, which correspond to the characteristic curves, are weighted for controlling the combustion device.

Still claimed EP1154202B2 the use of additional sensors to control the combustion device. Those additional sensors influence the positions of actuators of the combustion device based on their sensor results. Mentions as an example of measurement data obtained from those additional sensors EP1154202B2 a change in boiler temperature.

A patent application DE102004030300A1 was filed on June 23, 2004 by EBM PAPST LANDSHUT GMBH. The application was published on January 12, 2006. DE102004030300A1 deals with a method for setting an operating parameter of a combustion device.

• im Flammenkern,
• am Flammenfusspunkt,
• an der Flammenspitze,
• jedoch auch in einiger Entfernung von der Flamme, beispielsweise am Brennerblech selbst, angeordnet seien. Durch Ermittlung und Erfassung der im Wirkungsbereich der Brennerflamme gemessenen Ist-Temperaturen in Abhängigkeit von dem eingestellten Mischungsverhältnis werden der maximale Temperaturwert sowie das dazugehörige Mischungsverhältnis bestimmt.

DE102004030300A1 discloses a mixing area into which an air supply and a gas supply open. A line leads out of the mixing area. The line ends at a burner part. A flame is arranged above the burner part. A temperature sensor is optionally located on a surface of the burner portion. The temperature sensor can also be arranged at a different point in the range of action of the flame. The temperature sensor can

• in the flame core,
• at the base of the flame,
• at the tip of the flame,
• but also at some distance from the flame, for example on the burner plate itself. The maximum temperature value and the associated mixing ratio are determined by determining and recording the actual temperatures measured in the effective area of the burner flame as a function of the set mixing ratio.

Another patent application DE102004055716A1 was filed on November 18, 2004 by EBM PAPST LANDSHUT GMBH. The application was published on January 12, 2006.

DE102004055716A1 deals with a procedure for the regulation and control of a combustion device. DE102004055716A1 takes priority from June 23, 2004 claim.

DE102004055716A1 also discloses a mixing area into which an air supply and a gas supply open. A line leads out of the mixing area. The line ends at a burner part. A flame is arranged above the burner part. A temperature sensor can be arranged, for example, in the area of the flame, but also on the burner in the vicinity of the flame. For example, a thermocouple can also be used as a temperature sensor. DE102004055716A1 teaches the regulation of the temperature Tactual generated by a firing device _to a target temperature _Tsoll . In this case, a characteristic curve is used which indicates the setpoint temperature T _set as a function of the mass flow of air and/or the load of the firing device. The air ratio λ remains constant as a further parameter.

An international patent application WO2006/000367A1 was filed on June 20, 2005 by EBM PAPST LANDSHUT. The application was published on January 5, 2006.

WO2006/000367A1 deals with a method for setting an air ratio in a combustion device. WO2006/000367A1 claims a priority dated June 23, 2004.

• im Flammenkern,
• am Flammenfusspunkt,
• an der Flammenspitze,
• jedoch auch in einiger Entfernung von der Flamme, beispielsweise am Brennerblech selbst, angeordnet seien. Das Verfahren aus WO2006/000367A1 basiert darauf, dass die vom Temperatursensor erfasste Ist-Temperatur T_ist von einer Luftzahl λ abhängt. Die Ist-Temperatur erreicht bei λ = 1 ein Maximum T_max. Es wird nun für einen vorgegebenen Luftmassenstrom m_L anhand des Temperatursensors ein Maximum T_max bestimmt, indem iterativ ein Gasmassenstrom angepasst wird. Anschliessend wird eine Luftzahl von vorzugsweise λ = 1.3 eingestellt und der Luftmassenstrom m_L entsprechend erhöht.

WO2006/000367A1 also discloses a mixing area into which an air supply and a gas supply open. A line leads out of the mixing area. The line ends at a burner part. A flame is arranged above the burner part. A temperature sensor can be arranged, for example, in the area of the flame, but also on the burner in the vicinity of the flame. For example, a thermocouple can also be used as a temperature sensor. A temperature sensor is optionally located on a surface of the burner portion. The temperature sensor can also be arranged at a different point in the range of action of the flame. The temperature sensor can

• in the flame core,
• at the base of the flame,
• at the tip of the flame,
• but also at some distance from the flame, for example on the burner plate itself. The procedure off WO2006/000367A1 is based on the fact that the actual temperature T actual recorded by the temperature sensor _depends on an air ratio λ. The actual temperature reaches a maximum T _max at λ=1. A maximum T _max is now determined for a specified air mass flow m _L using the temperature sensor, in that a gas mass flow is iteratively adapted. An air ratio of preferably λ=1.3 is then set and the air mass flow m _L is increased accordingly.

Another international patent application WO2015/113638A1 was filed on February 3, 2014 by ELECTROLUX APPLIANCES AB, SE. The application was published on August 6, 2015. WO2015/113638A1 teaches a gas burner application as well as a gas cooking appliance.

WO2015/113638A1 discloses a monitoring device by means of which a gas supply is switched off in the absence of a flame. For this purpose, the monitoring device cooperates with a switch-off device comprising a valve. The monitor may include a thermocouple or other sensor. The monitoring device is therefore safety-related. A Japanese patent application JP2017040451A was filed on August 21, 2015 by NORITZ CORP . The application was published on February 23, 2017. JP2017040451A handles an incinerator.

In particular deals JP2017040451A with the detection of a flame temperature, taking into account the delays of the respective sensor. Thermocouples and thermistors are mentioned as sensors. A prediction unit is used to account for those delays. The prediction unit obtains a value by multiplying a difference between a temperature detected in the past and a current temperature by a coefficient. That value is added to the currently recorded temperature. The coefficient required to determine that value depends on a delay time and on a predetermined period of time.

DE10045272A1 discloses a firing device for gaseous fuels in which a plurality of temperature sensors are arranged in the flame area.

Delays caused by sensors are included in the 2020 technical specification of RTD platinum sensors from IST. The response time for a sensor to track 63 percent of a temperature change due to delays varies between 2.5 and 40 seconds. In general, the response time depends on the dimensions of the respective sensor.

A pneumatic gas-air combination and/or an electronic combination can be used to regulate a combustion device. Technically, a modulation range of one to seven can usually be achieved using a pneumatic gas-air combination.

During the combustion of pure hydrogen, no practically usable signal is formed at an ionization electrode. For this reason, ionization electrodes are hardly suitable for recording signals from the combustion of pure hydrogen. As a result, an electronic system controlled by a flame signal has so far only been technically feasible for combustible gases containing hydrocarbons.

Furthermore, in the case of an electronic system, the combustion output and the air supply only depend on the fan speed. If the use of other sensors is too complex, a correction of environmental influences is hardly possible. Such environmental influences relate, for example, to air temperature, air pressure and changes in the supply air path or exhaust gas path of the combustion device.

An electronic network for the combustion of hydrogen requires additional sensors, for example to detect and safeguard the amount of fuel gas, in order to adjust the amount of fuel gas without combustion control. Meanwhile, such additional sensors are expensive.

The aim of the present disclosure is to provide a closed-loop and/or open-loop control system that enables combustible gases containing hydrogen to be burned. In particular, an aim of the present disclosure is to provide regulation and/or control that achieves a sufficient degree of modulation. Such a regulation can also be used for fuel gases containing hydrocarbons and/or for a mixture of fuel gases containing hydrocarbons with hydrogen.

Summary

Regulating and/or controlling a combustion device on the basis of a single signal from a temperature sensor is tricky. The signal from the temperature sensor essentially depends on its position in the combustion chamber of a combustion device. It must be taken into account here that the temperature signal is a function of the supply of the fuel-air mixture and thus depends on the combustion output. In addition, the temperature signal also depends on the mixing ratio between fuel and air and thus on the air ratio. It is hardly possible to obtain an unambiguous assignment for a measured temperature value to exactly one combination of combustion output and air ratio with just one temperature sensor. Therefore, an additional signal is usually required. This signal is usually the air supply as a representative of a mixture supply or combustion output. With the measured temperature in or near the flame as a function of the measured value and the air supply, the air ratio can then be corrected using a specified characteristic curve. Such a procedure is in EP1902254B1 described, where in EP1902254B1 the measured temperature is given in the value range as a function of air ratio and combustion output. Alternatively, you can use the air ratio as an additional signal and use the air ratio and the measured temperature to determine the mixture supply, i.e. the combustion output. Recording or determining the fuel supply, in particular the gas supply, can also provide such an additional signal.

Correspondingly sufficiently precise sensors for determining the air supply, mixture supply or fuel supply are complex. A less complex sensor does not record any fluctuations in the ambient conditions such as air temperature, air pressure or fluctuations in the supply air path and/or exhaust gas path. Such a less complex sensor is, for example, the fan speed detection of the fan. Consequently, that sensor has the disadvantage that it only incompletely determines the air supply.

The present disclosure addresses those difficulties by placing more than one sensor in the furnace of a combustor. In particular, more than one temperature sensor placed in the firebox of the combustion device. The signals from both sensors, in particular both temperature sensors, are read out and processed into values for a combustion output. The signals from both sensors, in particular both temperature sensors, can likewise each be processed into a value for an air ratio λ. It can then be regulated and/or controlled on the basis of the determined combustion line and/or the determined air ratio λ.

The processing of the individual measurement signals taken individually to give a value for the combustion output or the air ratio or a combination of combustion output and air ratio is often not unambiguous.

In the case of an ambiguous assignment of individual signals to different burning powers, possible burning powers are determined which match the individual signals. Pairs are formed from burning powers, which were determined from the signals of the first mentioned sensor, and burning powers, which were determined from the signals of the second mentioned sensor. The pair with the smallest difference in combustion performance is selected. A current combustion output of the combustion device is determined on the basis of this pair.

Furthermore, those ambiguities can be resolved by arranging a further sensor, in particular a further temperature sensor, in the combustion chamber. A signal is read from the additional sensor, in particular from the additional temperature sensor. The signal read out is processed to a value of a combustion output and included in the determination of a current combustion output of the combustion device.

Another way to resolve ambiguities is to include a feed signal in the evaluation. Such a supply signal can be, for example, a fan speed of a fan in an air supply duct. Likewise, such a supply channel can be a signal from a flow sensor in the air supply channel or in the fuel supply channel. In addition, a supply signal can be obtained from an air damper position and/or from a position of a fuel actuator. The use of a feed signal has the advantage that the assignment of feed signal to combustion power is often unambiguous.

The two characteristic curves for determining the pairs of combustion output are specified for a specified air ratio. With the appropriate positioning of the two sensors in the combustion chamber, there is exactly one pair of points from the two sensor values at which both combustion outputs are the same for all possible air ratio values

With the method presented, the combustion output can be determined in the range of values as a function of the respective measurement signal for a specified target value of the air ratio. The determination is made for each sensor arranged in the combustion chamber. In this way, both the air ratio and the combustion output can be adjusted to specified target values. The combustion power depending on the associated sensor signal can be stored as a polynomial for both functions. In a In a preferred embodiment, the two functions can be stored as a sequence of points between which linear interpolation is carried out over the minimum distance between the two points. If additional sensors are used, a function of the combustion power is stored in the value range of three or more sensors. Another sensor can be, for example, a third sensor in the combustion chamber or a feed sensor.

The regulation takes place, for example, by first adjusting the air actuator or, alternatively, the fuel actuator until the combustion outputs from the two are the same or are close to one another. The combustion output is then calculated, for example, as the average of the two calculated combustion outputs. The air actuator and fuel actuator are then adjusted in such a way that the calculated combustion output is at its target value, for example via a control loop. Any resulting deviation of the air ratio from the target value is readjusted again via the air actuator or alternatively the fuel actuator. As a result of the readjustment, the combustion outputs calculated from the two measurement signals are the same again.

Alternatively, the air ratio and combustion output can be set together within a dead band of the target values using a multi-loop controller.

Changes caused by external influences on the fuel can be corrected by correcting the air ratio. A change in the fuel composition initially has an effect on the air ratio. A deviation in the air ratio is corrected by the method disclosed here. Likewise, a change in the fuel inlet pressure and/or the fuel temperature and/or the air pressure and/or the air temperature can be corrected via the air ratio control.

External influences on the combustion output can also be compensated for, since the combustion output can be recalculated and adjusted to a specified target value. Changes in the supply air/exhaust gas path can also be corrected with regard to the air ratio and the combustion output.

Brief description of the drawings

• FIG 1 zeigt eine Verbrennungsvorrichtung mit zwei Sensoren zur Flammenüberwachung im Feuerraum.
• FIG 2 zeigt den Verlauf der Brennleistung über das Messignal eines im Feuerraum angeordneten Sensors, wenn die Zuordnung eindeutig ist.
• FIG 3 zeigt den Verlauf der Brennleistung über den Signalen zweier im Feuerraum angeordneter Sensoren, wenn die Zuordnung eines Sensors nicht eindeutig ist.
• FIG 4 zeigt den Verlauf der Brennleistung über den Signalen zweier im Feuerraum angeordneter Sensoren, wenn sich die Signalverläufe kreuzen.
• FIG 5 zeigt den Verlauf der Brennleistung über den Signalen zweier im Feuerraum angeordneter Sensoren und den abweichenden Verlauf beider Signale, wenn das Gemisch abgemagert worden ist.
• FIG 6 zeigt den Verlauf der Brennleistung über den Signalen zweier im Feuerraum alternativ angeordneter Sensoren und den abweichenden Verlauf beider Signale, wenn das Gemisch abgemagert worden ist.
• FIG 7 zeigt den Verlauf der Luftzufuhr über dem Luftzufuhrsignal für zwei verschiedene Zuluft-Abgaswege.
• FIG 8 zeigt den Verlauf zweier vorgegebener Stellkurven für das Brenngasventil und die berechnete Stellkurve für die aktuellen Brennstoffparameter und/oder Gasparameter.

Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiments. The drawings that accompany the detailed description can be briefly described as follows:

• FIG 1 shows a combustion device with two sensors for flame monitoring in the combustion chamber.
• FIG 2 shows the course of the combustion output via the measuring signal of a sensor arranged in the combustion chamber, if the allocation is clear.
• 3 shows the course of the combustion output over the signals from two sensors arranged in the combustion chamber if the assignment of a sensor is not clear.
• FIG 4 shows the course of the combustion output over the signals of two sensors arranged in the combustion chamber when the signal courses cross.
• 5 shows the course of the combustion output over the signals from two sensors arranged in the combustion chamber and the deviating course of both signals when the mixture has become leaner.
• 6 shows the course of the combustion output over the signals from two sensors arranged alternatively in the combustion chamber and the deviating course of both signals when the mixture has become leaner.
• FIG 7 shows the course of the air supply over the air supply signal for two different supply air exhaust gas paths.
• 8 shows the course of two specified adjustment curves for the fuel gas valve and the calculated adjustment curve for the current fuel parameters and/or gas parameters.

Detailed description

FIG 1 Fig. 1 shows a combustion device 1 such as a wall-mounted gas burner and/or a floor-standing gas burner. During operation, a flame of a heat generator burns in the combustion chamber 2 of the combustion device 1 . The heat generator exchanges the thermal energy of the hot combustion gases into another fluid such as water. With the warm water, for example, a hot water heating system is operated and / or heated drinking water. According to another embodiment, a good can be heated, for example in an industrial process, with the thermal energy of the hot fuels and/or combustion gases. According to a further embodiment, the heat generator is part of a system with combined heat and power generation, for example a motor of such a system. According to another embodiment, the heat generator is a gas turbine. Furthermore, the heat generator can be used to heat water in a plant for the production of lithium and/or lithium carbonate. The exhaust gases 10 are discharged from the combustion chamber 2, for example via a chimney.

The air supply 5 for the combustion process is supplied via a (motor) driven fan. Via the signal line 14, a control and/or regulating device 13 specifies the air supply V _L to the blower that it is to convey. The fan speed of the fan speed sensor 12 thus becomes a measure of the air supply 5.

According to one embodiment, the fan speed determined by the sensor 12 is reported back to the control and/or regulating device 13 by the fan and/or by the drive 4 and/or the air actuator 4 of the fan. For example, the control and/or regulating device 13 determines the speed of the fan via the signal line 15.

The control and/or regulating device 13 preferably includes a microcontroller. The control and/or regulating device 13 ideally includes a microprocessor. The control and/or regulating device 13 can be a regulating device. The control device preferably includes a microcontroller. The control device ideally includes a microprocessor. The controller may include a proportional and integral controller. Furthermore, the control device can comprise a proportional and integral and derivative controller.

Furthermore, the control and/or regulating device 13 can comprise a (logic) gate arrangement which can be programmed in the field. In addition, the control and/or regulating device 13 can comprise an application-specific integrated circuit.

In one embodiment, the signal line 14 or 15 comprises an optical waveguide. In a special embodiment, the signal line 14 or 15 is designed as an optical waveguide. Optical fibers provide advantages in terms of galvanic isolation and protection against explosions.

If the air supply 5 is set via an air flap and/or a valve, the flap and/or valve position can be used as a measure for the air supply 5 . Furthermore, a measured value derived from the signal of a pressure sensor 12 and/or mass flow sensor 12 and/or volume flow sensor 12 can be used.

According to one embodiment, the air supply V _L is the value of the current air flow rate. The air flow rate may be measured and/or reported in cubic meters of air per hour. The air supply V _L can thus be measured and/or specified in cubic meters of air per hour.

The fuel supply V _B is set and/or regulated by the control and/or regulating device 13 with the aid of at least one fuel actuator 7-9 and/or at least one (motor-driven) adjustable valve 7-9. In execution in FIG 1 the fuel 6 is a fuel gas. A combustor 1 can then be connected to various fuel gas sources, for example sources with a high proportion of methane and/or sources with a high proportion of propane. Provision is also made for the combustion device 1 to be connected to a source of a gas or a gas mixture, the gas or the gas mixture comprising hydrogen. In a special embodiment it is provided that the gas or the gas mixture comprises more than five percent, in particular more than five percent of the amount of hydrogen. In a further special embodiment it is provided that the gas or the gas mixture only or includes essentially only hydrogen gas. In a further embodiment it is provided that the fuel and/or the gas and/or the gas mixture comprises variably zero to thirty percent of the amount of hydrogen gas. In FIG 1 the quantity of fuel gas is set by the control and/or regulating device 13 by at least one (motor-driven) adjustable fuel valve 7 - 9 . The control value, for example a pulse width modulated signal, of the gas valve 7 - 9 is a measure of the amount of fuel gas. It is also a value for the fuel supply V _B .

If a gas valve is used as the fuel actuator 7 - 9, the position of a valve can be used as a measure for the quantity of fuel gas. According to a specific embodiment, a fuel actuator 7-9 and/or a fuel valve 7-9 are set using a stepping motor. In that case, the stepping position of the stepping motor is a measure of the amount of fuel gas. The fuel valve and/or the fuel flap can also be integrated in a unit with at least one or more safety shut-off valves 7, 8. A signal line 16 connects the fuel actuator 7 to the control and/or regulating device 13. A further signal line 17 connects the fuel actuator 8 to the control and/or regulating device 13. Another further signal line 18 connects the fuel actuator 9 to the control and/or regulating device 13. or control device 13. In a special embodiment, the signal lines 16-18 each comprise an optical waveguide. Optical fibers provide advantages in terms of galvanic isolation and protection against explosions.

Furthermore, at least one of the fuel valves 7 - 9 can be a valve controlled internally via a flow and/or pressure sensor, which valve receives a target value and regulates the actual value of the flow and/or pressure sensor to the target value. The flow and/or pressure sensor can be implemented as a volume flow sensor, for example as a turbine wheel meter and/or as a bellows meter and/or as a differential pressure sensor. The flow and/or pressure sensor can also be designed as a mass flow sensor, for example as a thermal mass flow sensor.

FIG 1 also shows a combustion device 1 with a first sensor 19. The sensor 19 is preferably arranged in the combustion chamber 2. FIG. The first sensor 19 advantageously includes a first temperature sensor 19. Ideally, the first sensor 19 is a first temperature sensor 19.

A signal line 21 connects the temperature sensor 19 to the control and/or regulating device 13. In a specific embodiment, the signal line 21 comprises an optical waveguide. Optical fibers provide advantages in terms of galvanic isolation and protection against explosions.

FIG 1 also shows a combustion device 1 with a second sensor 20. The sensor 20 is preferably arranged in the combustion chamber 2. FIG. The second sensor 20 advantageously comprises a second temperature sensor 20. Ideally, the second sensor 20 is a second temperature sensor 20.

A signal line 22 connects the temperature sensor 20 to the control and/or regulating device 13. In a specific embodiment, the signal line 22 comprises an optical waveguide. Optical fibers provide advantages in terms of galvanic isolation and protection against explosions.

FIG 2 shows the signal curve 24 of the combustion output 23 over the sensor signal of the first sensor 19 for a solid combustion gas at a predetermined, constant mixing ratio. In FIG 2 the sensor 19 is arranged in such a way that the combustion output 23 can be clearly assigned to the sensor signal. Such a signal course 24 is obtained, for example, when a temperature sensor 19 is attached close to the burner 3 . Characteristic curve 24 differs from that in EP1902254B1 mentioned characteristic characterized in that the characteristic 24 along the ordinate has the burning power 23 and not the temperature signal. Consequently, via the in FIG 2 characteristic curve 24 shown from the signal, the combustion power 23 can be determined. The air ratio λ is set for each combustion output 23 for this purpose. In a preferred embodiment, the characteristic curve 24 is stored in the open-loop and/or closed-loop control device 13 . The assignment also takes place there. Alternatively, the characteristic curve 24 can be stored in an electronic circuit on the first temperature sensor 19 or in any other unit. The evaluation also takes place there.

The combustion output 23 can be determined directly with the characteristic curve 24, so that an air supply sensor is not required. If the fuel gas metering is assigned directly to the air supply 5, then the combustion output 23 and the air supply 5 are also assigned directly to one another. In this way, the air supply 5 can be set via the stated assignment between the combustion output 23 and the air supply 5 and via the control signal according to the line 14 . As an alternative, the air supply 5 can be regulated in this way via a closed loop control. In a preferred embodiment, the air supply signal is present, but the association between the air supply 5 and the signal is subject to external influences. These can be changes, for example, in the air temperature and/or the ambient pressure and/or the supply air/exhaust gas path. Typically, a signal where such changes are not compensated for is the fan speed signal of the fan 4 or the position feedback of a damper. The association between air supply 5 and the sensor signal on line 12 in relation to reference conditions can be recalibrated regularly during operation. The recalibration takes place with the help of the sensor signal and the combustion output 23 determined via the characteristic curve 24 as well as with the help of the assignment between the combustion output 23 and the air supply 5. This process has the advantage that the air supply 5 and thus the combustion output 23 can be changed quickly. In contrast, the correction via the characteristic curve 24 takes place much more slowly. The characteristic curve of a gas supply sensor can also be corrected, for example the fuel supply based on the position of a gas flap setting. The air control signal on line 14 and thus the air supply 5 are assigned directly to the fuel metering.

The course of the characteristic curve 24 depends heavily on the position of the sensor in the combustion chamber 2 . A sensor position close to or directly on the burner 3 has the disadvantage that the dynamics of the sensor signal is impaired by the heat capacity of the burner 3 . This makes the regulation sluggish. In addition, one would like to use the first sensor 19 at the same time for flame monitoring. In order for the flame to be monitored, the sensor 19 must be placed in a position in or near the flame area. For flame monitoring, sensor 19 should also react sufficiently quickly, ie have a sufficiently small time constant. 3 shows the course of a characteristic curve 24 of the combustion output 23 as a function of the sensor signal from line 21 when the sensor 19 is arranged in the combustion chamber 2 in or near the flame.

how to get in 3 sees, the sensor signal from line 21 can no longer be unambiguously assigned to the combustion output 23 via the characteristic curve 24 . Therefore, a second sensor 20 is installed in the combustion chamber 2, which assigns the sensor signal from line 22 to the combustion output 23 via a characteristic curve 25 that deviates from characteristic curve 24. So that a clear assignment of the two sensor values to the combustion output 23 as a function of two variables is possible via the two characteristic curves 24 and 25, for all values of the combustion output 23 in the value range of the possible combustion outputs 23, the pair of points with the signals on lines 21 and 22, the is assigned to the respective value of the combustion output 23 via the characteristic curves 24 and 25 only occur once.

For example, the two characteristic curves 24 and 25 can be stored as polynomials in the open-loop and/or closed-loop control device 13 . The assignment then takes place by means of a rule with which the different fuel gas outputs for the currently recorded signals 21 and 22 are calculated using the characteristic curves 24 and 25 . In a preferred embodiment, the characteristic curves 24 are stored as a sequence of pairs of values (21/23) and (22/23). The signals from the lines 21 and 22 can lie between the corresponding stored pairs of values (21/23) and (22/23). Adjacent pairs of values (21/23) and (22/23) corresponding to the signals from lines 21 and 22 are then determined. Linear interpolation is used to determine the combustion output 23 .

The discrepancies in the burning power 23 for the signals from the lines 21 and 22 are then determined. For this purpose, the absolute value of the difference between all calculated combustion powers 23 from characteristic curve 24 and all calculated values from characteristic curve is formed. For example, the mean value or one of the two calculated values is taken as the assigned value from the two combustion outputs 23 with the smallest difference. Exist for the signals from the lines 21, 22 in the characteristics 24, 25 only exactly one burning power 23 for at least one of the two characteristics 24, 25, so this is taken as the result.

FIG 4 shows that the two characteristic curves can also intersect. As long as the above-mentioned condition for the unambiguous assignment is met, the combustion output 23 and thus the air supply 5 can also be determined with such characteristic curves.

If the condition for the unambiguous association is not always met, the association can be made unambiguous with the aid of a further signal. This further signal can come from a further sensor in the combustion chamber 2, which clarifies this assignment in the case of the respective signals with an ambiguous assignment. With this further sensor in the combustion chamber 2, a further characteristic curve is stored, with which the combustion output 23 can be clearly determined as described above.

An air supply sensor and/or a fuel supply sensor is particularly preferred as the third sensor. If the fan speed or the position of an air damper is used as the air supply sensor, the returned signal on line 15 can be used to clarify the unambiguous assignment, despite the inaccuracies described above. Such a clarification can take place in particular when the combustible gas values with the same or similar pair of values are far apart. Advantageously, the fuel gas values with the same or a similar pair of measured values on the lines 21, 22 are not in the error range of the external influences mentioned.

With the presented method and the presented arrangement, however, the combustion output 23 and from this the air supply 5 can be determined not only from the signals on the lines 21, 22 of the sensors 19, 20 in the combustion chamber 2. Likewise, with the presented method and the presented arrangement, not only the fuel supply 6 can be determined for a fixed predetermined mixture of a fuel gas. The fuel, in particular the fuel gas, can also be metered in the correct ratio to the air supply 5 with the means presented. The prerequisite for this is that air supply 5 and fuel supply 6 can be freely adjusted via the respective actuators 4, 9 for air and for fuel. 5 shows the behavior of the signals on lines 21 and 22 over the burning power 23. 5 relates to the case that the mixture is too lean in relation to the set air ratio λ, i.e. there is too little fuel gas compared to the setpoint. The characteristic curves 24 and 25 correspond to the sensor signals on the lines 21 and 22 for different combustion outputs 23 when the mixture is set in such a way that the target air ratio λ _target is reached. If the mixture becomes leaner, the result is characteristic curve 26 for sensor 19 and characteristic curve 27 for sensor 20. Normally, characteristic curve 24 shifts to characteristic curve 25 by a different amount than characteristic curve 26 to characteristic curve 27 due to the leaner mixture.

In principle, for the desired correction of the air ratio λ, instead of the characteristic curves 24 and 25, two characteristic surfaces can be stored as a function of the combustion output 23 via the respective temperature values from the lines 21 and 22 and the air ratio λ in each case. The combustion output 23 and the air ratio λ can then be clearly determined. The prerequisite for this is that for each point of the combustion output 23 and the air ratio λ across all pairs of points that result, the pair of signal values from the lines 21, 22 occurs only once in both areas. Once the pair of points has been determined, the current combustion output 23 and the current air ratio λ can be assigned directly to the pair of points. The two actuators 4 and 9 can then be corrected to the setpoint.

The condition of unambiguous determination given for the correction cannot always be met for the two areas. A third signal is therefore often necessary in order to clearly determine the combustion output 23 and the air ratio λ. This third signal can come from another sensor in the combustion chamber. However, it is preferably the air supply signal from line 14 or 15. For example, the third signal can come from the fan speed feedback from a fan speed sensor 12 in the fan or the position of an air flap. Likewise, the third signal can come from the position of a fuel actuator, in particular from a position of a gas flap 9 . A positioning of the sensors in the combustion chamber to meet the requirements for an unambiguous assignment of the signals to combustion output 23 and/or air ratio λ in the value range is much easier to accomplish with the help of the additional, third sensor value.

Correspondingly, the correction of combustion output 23 and/or air ratio λ takes place when the mixture is richer than _setpoint air ratio λ set . Then the corresponding characteristic curve for a richer mixture is on the other side of the respective characteristic curve 24 or 25.

Storing two areas in the control and/or regulating device 13 is complex. Therefore, in a preferred procedure, only two functions 24, 25 of the combustion power 23 are stored as a function of the two sensor signals 21, 22 of the sensors 19, 20. The characteristic curves 24, 25 can each be stored as a polynomial as a function of a number of measurement signals. The characteristic curves 24, 25 can also be stored in the open-loop and/or closed-loop control device 13 as a sequence of points. Linear interpolation is preferably used between the points. Signals from other sensors on the combustion chamber and/or in the air supply 5 and/or in the fuel supply 6, such as a fan speed sensor 12, may also be added.

In a first variant, the regulation takes place by keeping the air supply 5 constant or almost constant via the air actuator 4 . The fuel supply 6 is changed by the fuel actuator 9 until the determined values of the combustion power 23 from the two characteristic curves 24, 25 are within a defined threshold value.

In a second variant, fuel supply 6 is kept constant or almost constant via fuel actuator 9 . The air supply 5 is changed via the air actuator 4 until the determined values of the combustion outputs 23 from the two characteristic curves 24, 25 are within a defined threshold value.

The adjustment direction is determined via the difference between the two determined combustion powers 23, for example by detecting that the difference is decreasing. If further sensor readings are added, the sum of the squared calculated difference values is compared with the specified threshold value, for example. This procedure ensures that the actual air ratio λ actual _is at the setpoint air ratio λ setpoint _specified according to the characteristic curves 24 , 25 . In the next In the first step, the combustion power P actual _is determined by, for example, calculating the arithmetic mean from the two combustion powers 23 determined with the aid of the characteristic curves 24 and 25 . After that, the air actuator 4 and at least one fuel actuator 7-9 are adjusted together until the specified combustion output P _setpoint is reached. The air ratio λ can deviate slightly due to the combustion output adjustment. In this case, the air ratio λ _can , as described, be readjusted by adjusting at least one fuel actuator 7-9 or the air actuator 4 at the target combustion output P setpoint .

In a third variant, combustion output 23 and air ratio λ are corrected directly by adjusting both actuators 4, 7-9. Reaching the respective threshold value for the difference in combustion power 23 is stored as a criterion in the multi-circuit control, as in the first and second variants.

In the variants mentioned above, almost constant means that the first actuator is adjusted more slowly than the second actuator. The target values for air ratio λ _target and combustion output P _{target can} always be achieved. In the second variant, at least one fuel actuator 7-9 is adjusted more slowly than air actuator 4. In the first variant, air actuator 4 is adjusted more slowly than at least one fuel actuator 7-9 Actuators 4 and 7 - 9 is utilized. The at least one fuel actuator 7-9 with a stepper motor drive is faster than the air actuator 4 with a fan wheel that can be adjusted by a motor and a corresponding moment of inertia. Variant one is therefore often chosen.

The procedure presented ensures that during a change in the combustion output, the air ratio λ is first corrected and only then the combustion output 23 . Thus, the combustion device 1 _is always operated with the correct air ratio λ set during the change in combustion output. For this reason, the characteristic curves 24, 25 also correspond to the characteristic curves of the combustion output 23 for the respective sensors 19, 20 at a predetermined air ratio λ _set . The setpoint air ratio λ _setpoint has a course over the combustion output 23 that is defined by the characteristic curves 24, 25 and is arbitrary over a wide range. For example, setpoint air ratio λ setpoint _can have an increasing or decreasing profile with combustion output 23 . In a special embodiment, the progression of setpoint air ratio λ _sol over combustion output 23 is constant.

In 6 the characteristic curve 24 of the first sensor 19 is shown at the air ratio target value λ _set and at the lean air ratio value 26 . Furthermore, the characteristic curve 25 of the second sensor 20 is shown at the air ratio target value λ _setpoint and at the lean air ratio value 27 . In particular with a third sensor signal, an unambiguous assignment of the sensor signals on the lines 21 and 22 to the air ratio λ can be achieved with such a course. Likewise, an unambiguous assignment to the combustion power 23 can be achieved. The third sensor signal can be, for example, a fan speed feedback from the fan 4 through the line 15 .

Air actuator 4 fuel factor 9 air actuator 4 air actuator 4 fuel factor 9 fuel factor 9 air actuator 4 During an adjustment of the combustion output 23 due to a changed combustion output requirement, the air actuator 4 can move on a predetermined characteristic of an air supply sensor 12 . The specified characteristic can be based, for example, on feedback of a fan speed or be a characteristic of a position feedback of an air valve. In FIG 7 such a characteristic curve 28 stored in the control and/or regulating device 13 is shown as a reference characteristic curve over the fan speed feedback 15 of a fan speed sensor 12 . The characteristic curve 28 relates to a specific and/or well-defined environmental condition.

A command signal along line 14 of the blower motor or damper position, as well as a feedback position signal along line 15, has a similar signal for a reference condition. The signal was linearized in advance via a characteristic stored in the control and/or regulating device 13 from the control signal or a reported position signal for the air supply 5 .

If the current combustion output 23 was determined after the air ratio λ had been corrected, the characteristic curve 28 can be adapted to the current ambient conditions. Such ambient conditions are, for example, air temperature and/or air pressure and/or changes in the supply air/exhaust gas path. The air supply 5 is known as a direct function of the combustion output 23 for the currently measured fan speed or reference control. A direct function means that the air supply 5 does not depend on any arguments of the function other than the combustion output 23 . The supply determined from characteristic curve 28 is also known. The correction factor can thus be determined for the current air supply 5 as a ratio between the two signals. Since the characteristic curves of the reference air supply signals or the fan speed feedback over the air supply 5 pass through the zero point, characteristic curve 28 can be corrected to characteristic curve 29 . Each characteristic value is multiplied by the determined correction factor. The combustion output 23 and the air supply 5 can be quickly adjusted via the corrected characteristic curve 29 with the aid of this method. Meanwhile, the air supply 5 can be corrected slowly via the characteristic curves 24, 25. In this way, both processes are decoupled from each other. Fluctuations in the measured values of the combustion output 23 can also be averaged out via an averaging filter, and the combustion output 23 can thus be determined in a stable manner. The combustion output 23 can also be corrected in this way. The speed of a combustion output change is not affected.

The characteristic on which the fuel actuator 9 moves is in 8 shown. Two reference characteristic curves 30, 31, which were determined for different pressures and/or different combustible gas compositions, are stored in the control and/or regulating device 13. The characteristic curves 30, 31 describe the gas metering signal over the air supply 5, represented by the corrected signal value of the air supply 5 or the combustion output 23. The In this case, the gas metering signal represents the fuel supply and/or gas supply. The two characteristic curves 30, 31 were determined under reference conditions, ie for specific inlet pressures and/or fuel gas compositions. The characteristic curve 30 was determined with a high-calorific fuel or combustible gas and/or with a high inlet pressure. The characteristic curve 31 was determined with a low-calorific fuel or combustible gas and/or with a low inlet pressure. In operation, it is determined what the current ratio between fuel gas and air is by shifting the signals from the sensors 19, 20 in the combustion chamber 2 as described above. The signals are shifted to an unambiguous pair of values on both characteristic curves 24 and 25 by changing the fuel actuator 9 up to this point.

With the current, corrected fuel supply 6 for the associated air supply 5, a ratio can be determined using the weighted average. The fuel metering signal and/or the gas metering signal are in this relationship. The ratio represents the current fuel parameters and/or gas parameters, such as fuel gas composition and/or inlet pressure and/or fuel gas temperature. Because the same ratio applies to all combustion output signals with the same fuel parameters and/or gas parameters, the characteristic curve 32 can be calculated. The fuel actuator 9 can quickly change its combustion output 23 on the characteristic curve 32 in accordance with the current fuel parameters and/or gas parameters. In particular, the fuel actuator 9 can quickly change its position based on the characteristic curve 32 according to the current fuel parameters and/or gas parameters.

If at least one fuel parameter and/or gas parameter changes, this is achieved by correcting the weighting ratio by adapting the sensor signals on lines 21 and 22 to the characteristic curves 24, 25 as described above. The new characteristic can be calculated with the new weighting parameter. The method for calculating the corrected characteristic curve 32 for controlling the fuel actuator 9 with different fuel parameters and/or gas parameters corresponds to the method as in FIG EP1154202B2 described. A change in the fuel composition or the gas inlet pressure can also be corrected with the method described, because these parameters affect the air ratio λ. The air ratio λ is corrected by adapting it to the characteristic curves 24, 25 as described above.

Another advantage of the method is that the flame can be monitored with the two sensors 19, 20, for example to detect a flame failure. For this purpose, the two signals 21, 22 generated by the sensors 19, 20 are used not only for controlling the air ratio λ and the combustion output 23 but also for detecting the presence of a flame.

At least one signal 21 or 22 can be evaluated for falling below a threshold value. The threshold values can be selected differently for sensor signal 21 than for sensor signal 22. If the respective threshold value is not reached, the temperature is so low, for example, that no flame can burn any longer. A signal is generated with which the Safety shut-off valves 8.9 are closed via the lines 16, 17 so that no combustible fuel can escape unburned. In a further variant, the difference between the two signals 21 and 22 is formed, it being necessary to ensure that both signals do not have the same temperature value during operation. If the flame goes out, the two temperatures quickly equalize. So if the difference between the two signals falls below a predetermined threshold value, this is detected as a loss of flame. It is ensured that the safety shut-off valves 8, 9 are closed.

According to one embodiment, the supply signal device (4, 7 - 9, 12) is an air supply sensor in or on an air supply duct. The air supply sensor can include, for example, a turbine wheel meter and/or a bellows meter and/or a differential pressure sensor and/or a mass flow sensor. In a special embodiment, the air supply sensor is a turbine wheel meter and/or a bellows meter and/or a mass flow sensor. In this case, the air supply sensor is in fluid connection with a fluid, in particular with air, in the air supply channel. The air supply sensor is also in operative connection with the fluid, in particular with air, in the air supply channel because the fluid acts on the air supply sensor. According to one embodiment, the supply signal device (4, 7 - 9, 12) comprises a fan (4) which acts on the air supply channel. The fan (4) can in particular be a motor-driven fan (4). The fan (4) is designed to signal, in particular to communicate, its fan speed. The fan speed of the fan (4) is a measure of the air supply (5). According to another embodiment, the supply signal device (4, 7 - 9, 12) is a fuel supply sensor in or on a fuel supply channel. The fuel supply sensor can include, for example, a turbine meter and/or a bellows meter and/or a differential pressure sensor and/or a mass flow sensor. In a specific embodiment, the fuel delivery sensor is a turbine meter and/or a bellows meter and/or a mass flow sensor. In this case, the fuel supply sensor is in fluid connection with a fluid, in particular with a fuel and/or with a fuel gas, in the fuel supply channel. The fuel supply sensor is also in operative connection with the fluid, in particular with the fuel and/or the fuel gas, in the fuel supply channel because the fluid acts on the fuel supply sensor. According to yet another embodiment, the supply signal device (4, 7-9, 12) comprises at least one fuel actuator (7-9) and/or at least one valve (7-9), which acts on the fuel supply channel. The at least one fuel actuator (7 - 9) and/or the at least one valve (7 - 9) can in particular be at least one fuel valve (7 - 9) and/or at least one fuel gas valve (7 - 9). The at least one fuel actuator (7 - 9) and/or the at least one valve (7 - 9) is designed to signal, in particular to communicate, its position. The position of the at least one fuel actuator (7 - 9) and/or the at least one valve (7 - 9) is a measure of the fuel supply (6).

The aforementioned disclosure presupposes that the two sensors (19, 20) are positioned in such a way that both temperature values cannot assume the same temperature value during operation when there is a flame in the combustion chamber (2), but the combustion performance (23) from the characteristic curves (24 , 25) can assume the same values.

The above relates to individual embodiments of the disclosure. Various changes can be made to the embodiments without departing from the basis lying idea and without departing from the scope of this disclosure. The subject matter of the present disclosure is defined by the claims thereof. It can various changes can be made without departing from the scope of protection of the following claims.

Reference sign

1. 1: combustion device
2. 2: firebox
3. 3: burner
4. 4: blower
5. 5: air supply
6. 6: fuel supply
7. 7: safety shut-off valve
8. 8: safety shut-off valve
9. 9: fuel metering valve, in particular fuel gas metering valve
10. 10: exhaust duct
11. 11: air supply signal
12. 12: Air supply sensor, e.g. fan speed sensor
13. 13: regulation and/or control device
14. 14: Line for the fan control signal
15. 15: Wire for air supply feedback, e.g. fan speed feedback
16. 16: Line for the control signal for a safety shut-off valve
17. 17: Line for the control signal for a safety shut-off valve
18. 18: Line for the control signal for a fuel metering valve
19. 19: first sensor in the combustion chamber
20. 20: first sensor in the combustion chamber
21. 21: Line for the measurement signal from the first sensor in the combustion chamber and signal from this line
22. 22: Line for the measurement signal from the second sensor in the combustion chamber and signal from this line
23. 23: burning power
24. 24: Characteristic of the combustion output over the measurement signal measured by the first sensor in the combustion chamber
25. 25: Characteristic of the combustion output over the measurement signal measured by the second sensor in the combustion chamber
26. 26: Characteristic of the combustion output over the measurement signal measured by the first sensor in the combustion chamber with a lean mixture
27. 27: Characteristic of the combustion output over the measurement signal measured by the second sensor in the combustion chamber with a lean mixture
28. 28: Characteristic of the air sensor signal before changing the exhaust path for modulation
29. 29: Characteristic curve of the air sensor signal after changing the exhaust path for modulation
30. 30: Control characteristic of fuel supply via fuel control for a high-calorific fuel, in particular a high-calorific combustible gas, and/or a high inlet pressure
31. 31: Control characteristic of fuel supply via fuel control for a low-calorific fuel, in particular a low-calorific fuel gas, and/or a low inlet pressure
32. 32: Characteristic curve determined by the combustion device to match the current fuel parameters and/or fuel gas parameters for modulation

Claims (10)

1. Method for regulating a combustion apparatus (1), the combustion apparatus (1) comprising a combustion chamber (2) and a first temperature sensor (19) in the combustion chamber (2) and a second temperature sensor (20) in the combustion chamber (2), wherein the second temperature sensor (20) is different from the first temperature sensor (19), the method comprising the steps:

   recording a first signal from the first temperature sensor (19) ;

   recording a second signal from the second temperature sensor (20);

   ascertaining at least one first combustion power (23) as a function of the first signal using a first characteristic curve (24), which indicates a progression of the combustion power (23) for the first temperature sensor (19) via the signal of the first temperature sensor (19);

   ascertaining at least one second combustion power (23) as a function of the second signal using a second characteristic curve (25), which indicates a progression of the combustion power (23) for the second temperature signal (20) via the signal of the second temperature sensor (20);

   ascertaining a current combustion power (23) of the combustion apparatus (1) as a function of the at least one first combustion power (23) and the at least one second combustion power (23); and

   regulating the current combustion power (23) of the combustion apparatus (1) to a setpoint power of the combustion apparatus (1).
2. The method according to claim 1, the combustion apparatus (1) additionally comprising at least one actuator selected from an air actuator (4) and a fuel actuator (7 - 9), the regulating of the current combustion power (23) of the combustion apparatus (1) to a setpoint power of the combustion apparatus (1) comprising the steps:

   forming a difference from the current combustion power (23) of the combustion apparatus (1) and the target power of the combustion apparatus (1);

   generating an actuator signal from the difference; and

   sending the actuator signal to the at least one actuator.
3. The method according to one of claims 1 to 2, the method comprising the steps:

   ascertaining at least one third combustion power (23) as a function of the first signal using the first characteristic curve (24), wherein the first characteristic curve (24) assigns the first signal at least two different combustion powers (23), so that the at least one third combustion power (23) is different from the at least one first combustion power (23) ;

   forming a first difference from the at least one first combustion power (23) and the at least one second combustion power (23);

   forming a second difference from the at least one third combustion power (23) and the at least one second combustion power (23);

   comparing the first difference with the second difference;

   selecting the at least one first combustion power (23), if the first difference is less than the second difference;

   selecting the at least one third combustion power (23), if the second difference is less than the first difference; and

   ascertaining the current combustion power (23) of the combustion apparatus (1) as a function of the selected combustion power (23) and the at least one second combustion power (23).
4. The method according to claim 3, the method comprising the step:
   ascertaining the current combustion power (23) of the combustion apparatus (1) as an arithmetic average of the selected combustion power (23) and the at least one second combustion power (23).
5. The method according to one of claims 1 to 4, the combustion apparatus (1) additionally comprising a further sensor in the combustion chamber (2), wherein the further sensor in the combustion chamber (2) is different from the first temperature sensor (19) and the second temperature sensor (20), the method comprising the steps:

   recording a further combustion signal from the further sensor;

   ascertaining at least one further combustion power (23) as a function of the further combustion signal using a further characteristic curve, which indicates a progression of the combustion power (23) for the further sensor via the signal of the further sensor; and

   ascertaining the current combustion power (23) of the combustion apparatus (1) as a function of the at least one first combustion power (23) and the at least one second combustion power (23) and the at least one further combustion power (23).
6. The method according to one of claims 1 to 5, the combustion apparatus (1) additionally comprising at least one supply channel in fluid communication with the combustion chamber (2), a supply signal facility (4, 7 - 9, 12) operatively connected to a fluid in at least one supply channel, wherein the supply signal facility (4, 7 - 9, 12) is arranged outside the combustion chamber (2), the method comprising the steps:

   recording a supply signal from the supply signal facility (4, 7- 9, 12);

   ascertaining a supply-based combustion power (23) as a function of the supply signal using a supply-based characteristic curve, which indicates a progression of the combustion power (23) for the supply signal facility (4, 7 - 9, 12) via the signal of the supply signal facility (4, 7 - 9, 12); and

   ascertaining the current combustion power (23) of the combustion apparatus (1) as a function of the at least one first combustion power (23) and the at least one second combustion power (23) and the supply-based combustion power (23) .
7. The method according to one of claims 1 to 6, the combustion apparatus (1) additionally comprising at least one actuator selected from an air actuator (4) and a fuel actuator (7 - 9), the method comprising the steps:

   sending a change signal to the at least one actuator;

   after sending a change signal to the at least one actuator:

   recording a third signal from the first temperature sensor (19) ;

   recording a fourth signal from the second temperature sensor (20);

   ascertaining at least one third combustion power (23) as a function of the third signal using the first characteristic curve (24);

   ascertaining at least one fourth combustion power (23) as a function of the fourth signal using the second characteristic curve (24); and

   ascertaining the current combustion power (23) of the combustion apparatus (1) as a function of the at least one first combustion power (23), the at least one second combustion power (23), the at least one third combustion power (23) and the at least one fourth combustion power (23).
8. Combustion apparatus (1) comprising a combustion chamber (2) and a first temperature sensor (19) in the combustion chamber (2) and a second temperature sensor (20) in the combustion chamber (2), wherein the second temperature sensor (20) is different from the first temperature sensor (19), at least one supply channel in fluid communication with the combustion chamber (2), at least one actuator selected from an air actuator (4) and a fuel actuator (7 - 9), wherein the at least one actuator acts on the at least one supply channel, the combustion apparatus (1) additionally comprising a regulation and/or control facility (13) in operative communication with the first temperature sensor (19), with the second temperature sensor (20) and with the at least one actuator, wherein the regulation and/or control facility (13) is configured to carry out a method according to one of claims 1 to 7.
9. Computer program product comprising commands that cause the combustion apparatus (1) of claim 8 to carry out the method steps according to one of claims 1 to 7.
10. Computer-readable medium, on which the computer program product according to claim 9 is stored.

Images