Fuel Type Recognition and/or Fuel Quantity Control and/or Air Volume Control

Abstract

Various embodiments include a method for estimating a flow value for fuels of different compositions supplied to a combustion device using a mass flow sensor. An example method includes: recording a first temperature of the fuel using a first resistor element; determining a compensable value with a heat output signal of a heating element; and estimating a flow value for the fuel supply by compensation of the value compensable as a function of the first temperature and/or as a function of the fuel composition and/or as a function of the fuel gas composition on the basis of at least one saved mapping rule dependent on the first temperature and/or on the fuel composition and/or on the fuel gas composition and on the basis of a calibration characteristic curve saved for a reference gas.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to EP Application No. 23186452.1 filed Jul. 19, 2023 and EP Application No. 23150542.1 filed Jan. 6, 2023, the contents of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to controllers. Various embodiments include open- and/or closed-loop controllers used in combustion devices, for example in gas burners, in connection with combustion sensors.

BACKGROUND

A combustion device's combustion rate must be known and/or set during operation. When combusting hydrocarbons or pure hydrogen or a mixture of the two, the air supply and fuel supply must be coordinated with one another. In this way, a correct air-fuel ratio λ is achieved. External influences may moreover have an impact on the air-fuel ratio and/or combustion rate. Such external influences are for example the input pressure of the fuel, in particular of the fuel gas, and the fuel composition. Further examples of external influences are ambient temperature, ambient pressure and changes in the supply air path and in the exhaust air path of the combustion device.

Sensors which monitor the flame for safety purposes may be included in the closed-loop control of a combustion device's combustion rate and/or air-fuel ratio. Optical flame monitoring has hitherto been used for the combustion of pure hydrogen in a combustion device. Optical sensors for recording signals during combustion are as yet complex.

European patent EP1154202B2 relates to a control device for a burner. The disclosure draws a distinction between fuel gases with a low and those with a high gross calorific value. Two characteristic curves are used to distinguish between the two fuel gases. Each of the two characteristic curves relate to a control signal for an actuating element of the combustion device via a blower speed of the combustion device. Control signals which correspond to the characteristic curves are weighted for controlling the combustion device.

EP1154202B2 furthermore claims the use of additional sensors for controlling the combustion device. On the basis of their sensor results, said additional sensors influence the positions of actuating elements of the combustion device. EP1154202B2 mentions a change in boiler temperature as an example of measurement data obtained from said additional sensors.

A further patent application DE102004055716A1 relates to a method for closed- and open-loop control of a firing means. The disclosure describes a mixing zone into which an air supply and a gas supply open. A line departs from the mixing zone. The line ends at a burner part. A flame is arranged above the burner part. A temperature sensor may for example be arranged in the region of the flame, but also on the burner in the vicinity of the flame. A thermocouple may, for example, also be used as a temperature sensor. DE102004055716A1 teaches controlling the temperature T_actual produced by a firing means to a setpoint temperature T_nominal. A characteristic curve is here used which indicates the setpoint temperature T_nominal as a function of the mass flow rate of air and/or the load on the firing means. The air-fuel ratio λ remains constant as a further parameter.

When pure hydrogen is combusted, virtually no usable signal is formed on an ionization electrode. Ionization electrodes are therefore largely unsuited to recording signals when pure hydrogen is combusted. As a consequence, an interconnected electronic system controlled on the basis of a flame signal has hitherto only been feasible for hydrocarbon-containing fuel gases.

Furthermore, in the case of an interconnected electronic system, the combustion rate and the air supply are solely dependent on blower speed. In the case of combustion rate, the air-fuel ratio λ must be kept constant for this purpose. If using other sensors is too complex, it is virtually impossible to correct for ambient influences. Such ambient influences relate, for example, to air temperature, air pressure and changes in the supply air path or exhaust air path of the combustion device.

A further European patent EP3301362B1 relates to recording a supply air stream on the basis of a mass flow sensor. The mass flow sensor may here be arranged in a side channel of an air supply channel of the combustion device. The air supply to the combustion chamber of the combustion device is determined on the basis of two actuators arranged in series. A first actuator receives a first signal which is a function of a requested flow rate. A second actuator receives a second signal which is a function of an output from the mass flow sensor. The combined closed- and open-loop control according to EP3301362B1 enables compensation of external influences on the air-fuel ratio and/or the combustion rate.

A further European patent EP2995861B1 likewise relates to mass flow sensors in relation to valve operation and diagnosis. According to EP2995861B1, a mass flow sensor which recognizes a flow of between 0.1 meters per second and 5 meters per second is used for leakage detection. One of at least two series-connected valves is firstly closed. Then a further valve is opened. Opening admits a stream of fluid.

A sensor for detecting an air stream is disclosed in an article: A 2D thermal flow sensor with sub-mW power consumption. Said article was published in 2010 in the journal Sensors and Actuators A: Physical, A163. The article was published on pages 449 to 456 of said journal. The article discloses a two-dimensional thermal mass flow sensor with heating elements and thermistors. The disclosed mass flow sensor comprises at least three temperature sensors in the form of three thermistors. A first and a second temperature sensor in the form of a first and second thermistor are here arranged on opposite sides of the heating element. A connection from the first to the second temperature sensor direction. defines a first A third temperature sensor in the form of a third thermistor is arranged in a second direction. The second direction is perpendicular to the first direction. The mass flow sensors from the above-stated article are claimed in claim 12 of a European patent EP3271655B1.

SUMMARY

The teachings of the present disclosure include closed- and/or open-loop controllers providing combustion of fuel gases of differing composition. The fuel gases may contain hydrogen gas. Some embodiments of the teachings herein include a closed- and/or open-loop controller which achieves a sufficient degree of modulation. Such a controller is usable for hydrocarbon-containing fuel gases and/or for a mixture of hydrocarbon-containing fuel gases with hydrogen and/or for pure hydrogen and/or for hydrogen-containing fuel gases with an inert gas fraction. Hydrogen here refers to hydrogen gas.

For example, some embodiments include a method for estimating a flow value (25) for fuels (6) and/or fuel gases (6) of different compositions which are supplied to a combustion device (1) via a fuel supply channel and/or fuel gas supply channel, wherein the combustion device (1) comprises a mass flow sensor (11), wherein the mass flow sensor (11) is in fluid connection with the fuel (6) and/or with the fuel gas (6), the method comprising: recording a first temperature signal, which indicates a first temperature of the fuel (6) and/or fuel gas (6), on the basis of a first resistor element (29) of the mass flow sensor (11); processing the first temperature signal to yield a first temperature (TM); determining a compensable value by recording a heat output signal, which indicates a heat output of a heating element (26) of the mass flow sensor (11); processing the heat output signal to yield a heat output; determining the compensable value as heat output; and estimating a flow value (25) for fuel supply and/or for fuel gas supply by compensation of the value compensable as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition on the basis of at least one saved mapping rule dependent on the first temperature (TM) and/or on the fuel composition and/or on the fuel gas composition and on the basis of a calibration characteristic curve saved for a reference gas.

In some embodiments, the combustion device (1) comprises a closed- and/or open-loop control unit (13) and a plurality of first mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) and a plurality of second mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) are saved in the closed- and/or open-loop control unit (13), the method comprising: recording the heat output signal, which indicates a heat output of a heating element (26) of the mass flow sensor (11); processing the heat output signal to yield the heat output; establishing a plurality of first estimated flow values (25) for the fuel supply and/or for the fuel gas supply by compensating the heat output as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of first, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a first, saved calibration characteristic curve; recording a second temperature signal and/or a third temperature signal; processing the second temperature signal to yield a second temperature (TD, TU) and/or the third temperature signal to yield a third temperature (TU, TD); determining the temperature difference (ΔTD, ΔTU, ΔTDU) between two different temperatures selected from: the first temperature (TM), the second temperature (TD, TU), and the third temperature (TU, TD); establishing a plurality of second estimated flow values (25) for the fuel supply and/or for the fuel gas supply by compensating the temperature difference (ΔTD, ΔTU, ΔTDU) as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of second, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a second, saved calibration characteristic curve; and estimating the type of fuel (6) and/or of fuel gas (6) on the basis of the plurality of first estimated flow values (25) and on the basis of the plurality of second estimated flow values (25).

In some embodiments, the method comprises: forming distances between flow values of the plurality of first estimated flow values (25) and the plurality of second estimated flow values (25); selecting the smallest distance from the distances formed; and estimating the type of fuel (6) and/or of fuel gas (6) by assigning the smallest distance to a fuel (6) and/or to a fuel gas (6).

In some embodiments, a plurality of third mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) are saved in the closed- and/or open-loop control unit (13), the method comprising: recording a fourth temperature signal, which indicates a fourth temperature of the fuel (6) and/or fuel gas (6), on the basis of a fourth resistor element (28, 27) of the mass flow sensor (11), wherein the fourth resistor element (28, 27) is different from the first resistor element (29) and from the second resistor element (27, 28) and wherein the fourth resistor element (28, 27) is arranged opposite the second resistor element (27, 28) up- or downstream relative to the heating element (26); processing the fourth temperature signal to yield a fourth temperature (TU, TD); calculating a second temperature difference (ΔTD, ΔTU, ΔTDU) between two different temperatures, selected from: the first temperature (TM), the second temperature (TD, TU), and the fourth temperature (TU, TD); establishing a plurality of third estimated flow values (25) for the fuel supply and/or for the fuel gas supply by compensating the second temperature difference (ΔTD, ΔTU, ΔTDU) as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of third, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a third, saved calibration characteristic curve; and estimating the type of fuel (6) and/or of fuel gas (6) on the basis of the plurality of first estimated flow values (25) and on the basis of the plurality of second estimated flow values (25) and/or on the basis of the basis of the plurality of third estimated flow values (25).

In some embodiments, the method comprises: forming first distances between flow values of the plurality of first estimated flow values (25) and the plurality of second estimated flow values (25); forming first squared distances by squaring the first distances; forming second distances between flow values of the plurality of first estimated flow values (25) and the plurality of third estimated flow values (25); forming second squared distances by squaring the second distances; forming third distances between flow values of the plurality of second estimated flow values (25) and the plurality of third estimated flow values (25); forming third squared distances by squaring the third distances; forming sum values by summing in each case a first squared distance selected from the first squared distances formed, in each case a second squared distance selected from the second squared distances formed and in each case a third squared distance selected from the third squared distances formed; selecting the smallest sum value from the sum values formed; and estimating the type of fuel (6) and/or of fuel gas (6) by assigning the smallest sum value to a fuel (6) and/or to a fuel gas (6).

In some embodiments, the method comprises selecting a value as a measure of a flow of the fuel (6) or fuel gas (6) from the plurality of first estimated flow values (25) and from the plurality of second estimated flow values (25).

In some embodiments, the method comprises selecting a value as a measure of a flow of the fuel (6) or fuel gas (6) from the plurality of first estimated flow values (25) and from the plurality of second estimated flow values (25) as a function of numerical values of the first estimated flow values (25) from the plurality of first estimated flow values (25) and as a function of numerical values of the second estimated flow values (25) from the plurality of second estimated flow values (25).

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a minimum air requirement (Lmin); and controlling at least one air actuator (3, 4) of the combustion device (1) as a function of the assigned minimum air requirement (Lmin).

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); establishing a correction factor from the assigned calorific value (Hu) and a set calorific value of the combustion device (1); and correcting an air supply (5) of the combustion device (1) on the basis of at least one air actuator (3, 4) of the combustion device (1) or on the basis of the at least one air actuator (3, 4) of the combustion device (1) in proportion to the correction factor.

In some embodiments, the method comprises: correcting an operating characteristic curve on the basis of the estimated type of fuel (6) and/or on the basis of the estimated type of fuel gas (6), wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply (16) and/or fuel gas supply (16), or a second operating characteristic curve between temperature-compensated difference and fuel supply (16) and/or fuel gas supply (16); determining a current fuel supply and/or a current fuel gas supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and controlling at least one fuel actuator (7, 8) of the combustion device (1) as a function of the current fuel supply and/or the current fuel gas supply.

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); correcting an operating characteristic curve on the basis of the assigned calorific value (Hu), wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply (16) and/or fuel gas supply (16), or a second operating characteristic curve between temperature-compensated difference and fuel supply (16) and/or fuel gas supply (16); determining a current fuel supply and/or a current fuel gas supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and controlling at least one fuel actuator (7, 8) of the combustion device (1) as a function of the current fuel supply and/or the current fuel gas supply.

In some embodiments, the combustion device (1) comprises a closed- and/or open-loop control unit (13) with an operator control unit and wherein a plurality of mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM), are saved in the closed- and/or open-loop control unit (13), the method comprising, on setting the combustion device (1), selecting the saved mapping rules, dependent on the first temperature (TM) and/or on the fuel composition and/or on the fuel gas composition, from the plurality of mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53), with the assistance of the operator control unit.

As another example, some embodiments include a combustion device (1) comprising a combustion chamber (2), a fuel supply channel for the supply of a fuel (6) and/or fuel gas (6) to the combustion chamber (2), a mass flow sensor (11) in or on the fuel supply channel and a closed- and/or open-loop control unit (13) in communicative connection with the mass flow sensor (11); wherein the mass flow sensor (11) comprises a heating element (26), a first resistor element (29) and a second resistor element (27, 28) different from the first resistor element (29) and arranged up- or downstream of heating element (26), and/or a third resistor element (28, 27) different from the first resistor element (29) arranged up- or downstream of heating element (26) and/or a fourth resistor element (28, 27) different from the first (29) and second (27, 28) resistor elements and arranged up- or downstream relative to heating element (26) opposingly relative to the second resistor element (27, 28), wherein the closed- and/or open-loop control unit (13) is configured to carry out one or more of the methods described herein.

As another example, some embodiments include a computer program product comprising commands which cause a combustion device incorporating teachings of the present disclosure to carry out one or more elements of a method described herein. As another example, some embodiments include a computer-readable data storage medium storing a computer program product as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will be apparent to a person skilled in the art from the following detailed description of the disclosed, non-limiting embodiments. The drawings appended to the detailed description can be briefly described as follows:

FIG. 1 shows a combustion device incorporating teachings of the present disclosure with a mass flow sensor in the fuel supply channel;

FIG. 2 shows a sensor element incorporating teachings of the present disclosure exposed to flow with various resistor elements;

FIG. 3 shows application of the resistor elements of the sensor element onto a thin layer and/or film incorporating teachings of the present disclosure;

FIG. 4 shows a sensor monitoring unit incorporating teachings of the present disclosure communicatively connected to the resistor elements;

FIG. 5 shows a plot of a temperature difference against the supply of fuel and/or fuel gas;

FIG. 6a to FIG. 6c show plots of temperature differences for various fuels and/or fuel gases; and

FIG. 7a to FIG. 7c show plots of heat outputs against supply of fuel and/or fuel gas for various fuels and/or fuel gases.

DETAILED DESCRIPTION

Before the air supply and/or power of a combustion device is controlled, the type of fuel and/or fuel gas must be estimated and/or determined and/or calculated. A mass flow sensor in a fuel supply channel of the combustion device may be used for this purpose. The mass flow has a heating element. A heat output is firstly established from a signal of the mass flow sensor.

A plurality of temperatures are furthermore established on the basis of resistor elements of the mass flow sensor. A difference between the established temperatures is calculated. Both the heat output and the difference are then temperature-compensated.

The temperature-compensated values can be compared with reference values. Reference values are available for example for methane as fuel gas or for molecular hydrogen as fuel gas or for other fuel gas compositions. On the basis of the comparison, the type of fuel or fuel gas can be estimated and/or determined and/or calculated.

The heat output may be temperature-compensated on the basis of a first, empirically established calibration characteristic curve and/or on the basis of a first, empirically established calibration function. The difference is preferably temperature-compensated on the basis of a second, empirically established calibration characteristic curve. The first, empirically established calibration characteristic curve is advantageously different from the second, empirically established calibration characteristic curve.

The type of fuel gas and/or fuel is estimated and/or determined and/or calculated by establishing a distance. Distances of pairs of values of temperature-compensated heat output and temperature-compensated difference from the corresponding pairs of values of the reference gases are established. The fuel and/or the fuel gas is estimated in accordance with the shortest distance from one of the reference gases such as for example methane, ethane, or molecular hydrogen.

The combustion device may be controlled on the basis of the estimation and/or determination and/or calculation of the type of fuel gas and/or fuel. For this purpose, a minimum air requirement may, for example, be assigned to a type of fuel gas and/or fuel. Using the minimum air requirement and the requested power output, it is possible to establish the necessary air throughput. The air supply setpoint permits control of the combustion device for example via at least one air actuator thereof.

A calorific value may likewise be assigned to a type of fuel gas and/or fuel. The calorific value is compared with a set calorific value. The set calorific value may for example be that calorific value which is set on the combustion device before the type of fuel gas and/or fuel is estimated and/or determined and/or calculated. A correction factor is established by relating or normalizing the assigned calorific value to the set calorific value. This enables for example the air supply to the combustion device to be modified in proportion to the correction factor.

Teachings of the present disclosure may establish the correct assignment between the measured value and fuel supply on the basis of the estimated or determined type of fuel gas or fuel. The current fuel supply may be determined on the basis of the measured value. The measured value is here the heat output of the mass flow sensor and/or one or more of the temperature differences from the measured temperatures of the temperature sensors. The fuel mass flow rate or the fuel volume flow rate or the fuel velocity may be used as the fuel supply. One of these values may also be used with reference to specific ambient conditions.

On the basis of the determined variable, the controller of the combustion device can set the current fuel supply and, on the basis of a correspondingly specified setpoint, the fuel supply and/or fuel gas supply. The fuel supply and/or fuel gas supply is set with the assistance of a fuel actuator.

The current combustion rate may furthermore be established on the basis of the estimated or determined type of fuel gas or fuel and the assigned calorific value. In this case too, on the basis of the determined variable for the current combustion rate and a specified setpoint, the controller of the combustion device can set the combustion rate with the assistance of at least one fuel actuator.

FIG. 1 shows a combustion device 1 incorporating teachings of the present disclosure such as for example 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 transfers the thermal energy of the hot fuel gases into another fluid such as for example water. The hot water is used, for example, to operate a hot water heating system and/or to heat drinking water. According to another embodiment, the thermal energy of the hot fuels and/or fuel gases can be used to heat an article, for example in an industrial process. According to a further embodiment, the heat generator is part of a system using a combined heat and power cycle, for example a motor of such a system. In some embodiments, the heat generator is a gas turbine. The heat generator may further serve to heat water in a system for recovering lithium and/or lithium carbonate. The exhaust gases are discharged from the combustion chamber 2 for example via a flue 9.

The air supply 5 for combustion is supplied via a motor-driven blower 3 to the combustion chamber 2 through the air supply channel 10. The necessary volume of combustion air is defined by a closed- and/or open-loop control unit 13. The value is transferred to the blower 3 with drive signal 15. It should be assumed that the blower 3 also achieves the defined air throughput level. This may proceed, for example, by internal speed controller and/or an internal controller via an air volume flow rate sensor or air mass flow rate sensor, not shown here. The corresponding control unit may also be integrated in the closed- and/or open-loop control unit 13.

In some embodiments, the closed- and/or open-loop control unit 13 comprises a microcontroller and/or microprocessor. In some embodiments, the closed- and/or open-loop control unit 13 is a microcontroller and/or microprocessor. The closed- and/or open-loop control unit 13 preferably comprises a memory such as for example a nonvolatile memory.

In some embodiments, the air supply 5 can be set and/or adjusted by an air throttle valve 4. The driven signal 14 is also actually set by the air throttle valve 4. A requested signal 14 can further be adjusted by the air throttle valve 4. This may proceed for example by a position feedback means provided internally in the air throttle valve 4 or via an air volume flow rate sensor or air mass flow rate sensor. The previously mentioned European patent EP3301362B1 describes a controller for two air actuators. The blower 3 may, however, also have a fixed speed and only the air throttle valve 4 may be adjustable and/or controllable. The air throttle valve 4 may furthermore be entirely omitted.

The fuel 6 is supplied from the fuel source, e.g. a gas grid or a gas tank, via a mass flow sensor 11 and at least one motor-driven fuel valve 7, 8. The fuel 6 may be supplied via a mass flow sensor 11 and two motor-driven fuel valves 7, 8. The fuel 6 is then combusted with the supplied air 5.

The at least one fuel valve 7, 8 takes the form of a safety shutoff valve. As a consequence, in the event of a shutoff signal from the closed- and/or open-loop control unit 13, the supply of fuel 6 can be completely interrupted on the basis of signals 19 and/or 20. A flame in the combustion chamber 2 is therefore extinguished.

The two fuel valves 7, 8 may take the form of safety shutoff valves. The two motor-driven shutoff valves 7, 8 are here arranged in series. As a consequence, in the event of a shutoff signal from the closed- and/or open-loop control unit 13, the supply of fuel 6 can be completely interrupted on the basis of signals 19 and/or 20. A flame in the combustion chamber 2 is therefore extinguished.

At least one motor-driven valve 7, 8 is additionally settable and/or adjustable continuously or with intermediate positions from the completely closed state to a completely open state. The supply of fuel 6 can be set by the degree of opening of the fuel valve 7, 8 on the basis of the flow rate measured by the mass flow sensor 11. The setting is made to a specified setpoint. In some embodiments, the supply of fuel 6 can be adjusted by the degree of opening of the fuel valve 7, 8 on the basis of the flow rate measured by the mass flow sensor 11. The adjustment is made to a specified setpoint.

Two motor-driven valves 7, 8 can moreover additionally be settable and/or adjustable continuously or with intermediate positions from the completely closed state to a completely open state. The two motor-driven fuel valves 7, 8 may be arranged in series. The supply of fuel 6 can be set by the degrees of opening of the two fuel valves 7, 8 on the basis of the flow rate measured by the mass flow sensor 11. The setting is made to a specified setpoint. In some embodiments, the supply of fuel 6 can be adjusted by the degrees of opening of the fuel valves 7, 8 on the basis of the flow rate measured by the mass flow sensor 11. The adjustment is made to a specified setpoint.

The at least one settable fuel valve 7, 8 need not necessarily take the form of a safety shutoff valve. The supply of fuel 6 is then defined and/or controlled via an additional, settable fuel valve. The position of the additional, settable fuel valve is adjusted by the control loop in the closed- and/or open-loop control unit 13 with the assistance of the signal from the mass flow sensor 11. The supply of fuel 6 is therefore also adjusted.

In some embodiments, the two settable fuel valves 7, 8 need not necessarily take the form of a safety shutoff valve. It is also possible to use two independent safety shutoff valves 7, 8 which can only completely open and close. The supply of fuel 6 is then defined and/or controlled via an additional, settable fuel valve. The position of the additional, settable fuel valve is adjusted by the control loop in the closed- and/or open-loop control unit 13 with the assistance of the signal from the mass flow sensor 11. The supply of fuel 6 is therefore also adjusted.

In some embodiments, the mass flow sensor 11 comprises a measurement and control unit 12. The measurement and control unit 12 processes the captured measurement signals. Three signals 16, 17 and 18 are transmitted to the closed- and/or open-loop control unit 13. These signals contain information about the volumetric flow rate and about the fuel composition and/or fuel gas composition. In a compact embodiment, the mass flow sensor 11 does not comprise the measurement and control unit 12. Instead, the measurement and control unit 12 may be entirely or in part integrated in the closed- and/or open-loop control unit 13.

In some embodiments, the measurement and control unit 12 of the mass flow sensor 11 comprises a microcontroller and/or microprocessor. In some embodiments, the measurement and control unit 12 of the mass flow sensor 11 is a microcontroller and/or microprocessor. The measurement and control unit 12 of the mass flow sensor 11 may comprise a memory such as for example a nonvolatile memory.

In some embodiments, the mass flow sensor 11 comprises the measurement and control unit 12 and a sensor element 21. FIG. 2 and FIG. 3 show the structure of the sensor element 21. The sensor element 21 comprises a sensor substrate. A thin layer and/or film 22 is applied to the sensor substrate. Beneath the areas 23 and 24, the sensor substrate or part of the sensor substrate is removed. As a consequence, the temperature-dependent resistor elements 26, 27, 28 and 29 lie practically only on the thin layer and/or film 22. Resistor elements 26, 27, 28 and 29 are thus thermally decoupled from the sensor substrate. Resistor elements 26, 27, 28 and 29 are preferably effectively thermally decoupled from the sensor substrate. Resistor elements 26, 27, 28 and 29 are ideally highly effectively thermally decoupled from the sensor substrate.

The temperatures of resistor elements 26, 27, 28 and 29 change rapidly due to the low heat capacity of the resistor elements and low heat dissipation. The temperatures resistor elements 26, 27, 28 and 29 may change very rapidly due to the low heat capacity of the resistor elements and low heat dissipation. A flowing medium such as for example a fuel gas 6 flows over the areas 23 and 24 and thus over resistor elements 26, 27, 28 and 29. As shown in FIG. 4, resistor elements 26, 27, 28 and 29 are driven by the measurement and control unit 12.

In some embodiments, the measurement and control unit 12 comprises one or more digital-analog converters for driving resistor elements 26, 27, 28 and 29. The one or more digital-analog converters convert digital drive signals to resistor elements 26, 27, 28 and 29 into analog signals. The one or more digital-analog converters may for example be used to pass an electrical current through one of resistor elements 26, 27, 28 and 29. The electrical current may be a specified electrical current.

In some embodiments, the one or more digital-analog converters may be entirely integrated into the measurement and control unit 12. In particular, the one or more digital-analog converters and the measurement and control unit 12 may form a single-chip system. The one or more digital-analog converters and a microcontroller of the measurement and control unit 12 may accordingly form a single-chip system. The one or more digital-analog converters and a microprocessor of the measurement and control unit 12 may further form a single-chip system.

In some embodiments, and control unit 12 comprises one or more analog-digital converters for reading in the signals from resistor elements 26, 27, 28 and 29. The one or more analog-digital converters convert analog signals at the resistor elements 26, 27, 28 and 29 into digital signals. The one or more analog-digital converters may for example be used to read in an electrical voltage at one of resistor elements 26, 27, 28 and 29. In some embodiments, the one or more analog-digital converters may be entirely integrated into the measurement and control unit 12. In particular, the one or more analog-digital converters and the measurement and control unit 12 may form a single-chip system. The one or more analog-digital converters and a microcontroller of the measurement and control unit 12 may accordingly form a single-chip system. The one or more analog-digital converters and a microprocessor of the measurement and control unit 12 may further form a single-chip system.

The measurement and control unit 12 of the mass flow sensor 11 comprises a sensor monitoring unit 32 such as for example a central sensor monitoring unit 32. The sensor monitoring unit 32 supplies resistor elements 27, 28 and 29 located on the sensor element 21 with a current. The sensor monitoring unit 32 further supplies a reference resistor 30 located in the measurement and control unit 12 with a constant electrical current.

The constant electrical current may be selected to be so low that the resistor elements 27, 28 and 29 are virtually unheated by this current. With the assistance of the known value of the reference resistor 30, the electrical current through resistor elements 27, 28 and 29 can be accurately established on the basis of a measured electrical voltage 37. On the basis of electrical voltages 34, 35 and 36 and on the basis of the established electrical current, it is possible to calculate the temperature-dependent values of resistor elements 27, 28 and 29. The calculation is preferably performed by the sensor monitoring unit 32.

In some embodiments, the sensor monitoring unit 32 comprises a microcontroller and/or a microprocessor. In some embodiments, the sensor monitoring unit 32 is a microcontroller and/or a microprocessor. In some embodiments, the sensor monitoring unit 32 comprises a memory such as for example a nonvolatile memory. In some embodiments, the central sensor monitoring unit 32 comprises a microcontroller and/or a microprocessor. In some embodiments, the sensor monitoring unit 32 is a microcontroller and/or a microprocessor. In some embodiments, the central sensor monitoring unit 32 comprises a memory such as for example a nonvolatile memory.

The at least one analog-digital converter for reading in the signals from resistor elements 26, 27, 28 and 29 is furthermore preferably integrated in the sensor monitoring unit 32. In some embodiments, the at least one analog-digital converter for reading in the signals from resistor elements 26, 27, 28 and 29 is provided separately from the sensor monitoring unit 32. In some embodiments, the signal is then transferred via a bus from the at least one analog-digital converter to the sensor monitoring unit 32. An SPI bus or a CAN bus may, for example, be considered as the bus.

Given a known resistance-temperature characteristic curve, the temperature of the respective resistor element 27, 28 and 29 can be determined on the basis of the respective resistance values. The resistance-temperature characteristic curve for each of the three resistor elements 27, 28 and 29 is preferably established by way of temperature calibration. The resistance-temperature characteristic curve for each of the three resistor elements 27, 28 and 29 may be saved in the sensor monitoring unit 32. The resistance-temperature characteristic curve for each of the three resistor elements 27, 28 and 29 may, for example, be saved in a nonvolatile memory of the sensor monitoring unit 32.

Resistor element 29 is here thermally decoupled from the other resistor elements 26, 27 and 28 since it is located on its own thermal island. Using resistor element 29, a signal which virtually exclusively indicates a temperature of the flowing fuel 6 can thus be established and/or recorded. Using resistor element 29, a signal which virtually exclusively indicates a temperature of the flowing fuel gas 6 can thus preferably be established and/or recorded. Using resistor element 29, a signal which very accurately indicates a temperature of the flowing fuel 6 can be established and/or recorded. Using resistor element 29, a signal which very accurately indicates a temperature of the flowing fuel gas 6 can ideally be established and/or recorded.

The resistor element 26 acts as heater and temperature sensor. On the basis of the resistor element 26, it is possible to record a signal which indicates the temperature TH of resistor element 26 configured as heating resistor 26. For heating, the sensor monitoring unit 32 applies the voltage via heating resistor 26 and series resistor 31 to a driver 33. The driver 33 provides sufficient current and power to heat the resistor element 26.

With the assistance of the electrical voltage 39 across series resistor 31, the sensor monitoring unit 32 can determine the current through the heating resistor 26. Using the calculated current and electrical voltage 38, it is possible to calculate the temperature-dependent value of the heating resistor 26. The temperature-dependent value of the heating resistor 26 is preferably calculated by the sensor monitoring unit 32.

On the basis of a resistance-temperature characteristic curve and on the basis of the temperature-dependent value of the heating resistor 26, the temperature TH of the heating resistor 26 can be accurately determined. The resistance-temperature characteristic curve for the heating resistor 26 may be likewise established by way of temperature calibration. The resistance-temperature characteristic curve for the heating resistor 26 may be saved in the sensor monitoring unit 32. The resistance-temperature characteristic curve for the heating resistor 26 can, for example, be saved in a nonvolatile memory of the sensor monitoring unit 32.

Using the voltage level at the output of the driver 33, the temperature TH of the heating resistor 26 can thus be set or adjusted. The temperature TH of the heating resistor 26 can be measured and/or established by way of voltages 38 and 39. The heating resistor 26 is operated in “constant temperature anemometer” (CTA) mode. This means that the temperature of the heating resistor 26 is adjusted by way of temperature control to a constant overtemperature of ΔTH. The overtemperature ΔTH denotes a difference between a temperature TH of the heating resistor 26 and a temperature TM of the fuel 6:

$\Delta TH=TH-TM$

A signal which indicates a temperature TM of the fuel 6 is here recorded on the basis of the resistor element 29. The overtemperature ΔTH advantageously denotes a difference between a temperature TH of the heating resistor 26 and a temperature TM of the fuel gas 6:

$\Delta TH=TH-TM$

A signal which indicates a temperature TM of the fuel gas 6 is here recorded on the basis of the resistor element 29. Temperature control to a constant overtemperature is preferably carried out by the sensor monitoring unit 32. Temperature control to a constant overtemperature is ideally carried out by a closed-loop controller in the sensor monitoring unit 32. The overtemperature ΔTH typically has values of 20 kelvin, 40 kelvin, 60 kelvin, or even 80 kelvin.

When fuel is flowing over the heating resistor 26, the heating resistor 26 is cooled to a differing extent depending on the flow velocity 25 and composition of the fuel 6. The fuel 6 may be a fuel gas. In this case, the heating resistor 26 is cooled to a differing extent depending on the flow velocity 25 and composition of the fuel 6. If, given an identical fuel composition and/or fuel gas composition, the flow velocity 25 increases, the heating resistor 26 will also be more strongly cooled.

If overtemperature ΔTH is to remain constant, the temperature controller must correspondingly increase heat output PH in the event of stronger flow. In FIGS. 7a, 7b and 7c, heat output PH is plotted along the vertical axis as signal 48. Signal 16 is a measure of a supply of fuel 6 and/or of the supply of fuel gas 6. In particular, signal 16 is a measure of a mass flow rate of fuel 6 and/or fuel gas 6.

Heat output PH is thus a measure of flow velocity over the mass flow sensor 11. Heat output PH can be calculated from measured voltages 38 and 39 using the known series resistor 21. PH is preferably calculated in the sensor monitoring unit 32.

Resistor elements 27 and 28 are located to the side of heating resistor 26. If the heating resistor 26 is heated by a value ΔTH above the fuel gas temperature TM, the two resistor elements 27 and 28 are likewise heated. Resistor elements 27 and 28 are heated because they are thermally coupled via the thin layer and/or film 22 and the flowing fuel 6 to heating resistor 26. Thermal coupling may proceed via the thin layer and/or film 22 and the flowing fuel 6 and/or flowing fuel gas 6.

By way of the respective resistance-temperature characteristic curves of resistor elements 27 and 28, the respective resistor temperatures can be established on the basis of the measured resistance values of 27 and 28. The resistance-temperature characteristic curves of resistor elements 27 and 28 may be saved in the sensor monitoring unit 32. The resistance-temperature characteristic curves of resistor elements 27 and 28 are ideally saved in a nonvolatile memory of the sensor monitoring unit 32.

Resistor element 27 is located upstream relative to heating resistor 26. An upstream resistor temperature TU is therefore established on the basis of resistor element 27. Resistor element 28 is downstream located relative to heating resistor 26. A downstream resistor temperature TD is therefore established on the basis of resistor element 28.

Both temperatures TU and TD are caused by the overtemperature ΔTH relative to the temperature TM of the fuel 6 and/or fuel gas 6. As a consequence, two further differences

$\Delta TU=TU-\mathrm{TM}\mathrm{and}\Delta \mathrm{TD}=\mathrm{TD}-TM$

may be calculated. Differences ΔTU and ΔTD may be calculated by the sensor monitoring unit 32. Difference ΔTU corresponds to signal 16. Difference ΔTD corresponds to signal 17. Heat output PH corresponds to signal 18. Difference ΔTD and heat output PH may be temperature-compensated by the closed- and/or open-loop control unit 13.

If, given an identical fuel gas composition, flow velocity is raised, ΔTU (signal 16) falls. The reason for this is that resistor element 27, with which ΔTU (signal 16) is determined, receives its heat exclusively via thermal conduction of the thin layer or film 22. As soon as the medium flows over the sensor element 21, the heat is blown away from resistor element 27. As a consequence, no or scarcely any heat is transferred from heating resistor 26 to resistor element 27 via the fuel 6 and/or fuel gas 6.

In the event of an increasing flow velocity 25, the heat supplied to the resistor element 27 via the thin layer and/or film 22 is increasingly carried away by the flowing fuel 6 and/or fuel gas 6. As a consequence, the resistor element 27 is increasingly cooled. Difference ΔTU (signal 16) therefore declines with increasing flow velocity 25.

If the flow velocity 25 is then kept constant and the composition of the fuel 6 and/or fuel gas 6 is changed, the heating resistor 26 is firstly cooled to a greater or lesser extent.

However, temperature control keeps the temperature value of the heating resistor 26 constant. Temperature control may be performed by the sensor monitoring unit 32.

The resistor element 27 is likewise cooled by the same amount more or less. Due to the strong thermal coupling of the resistor element 27 to the heating resistor 26 via the thin layer and/or film 22, this t loss is also compensated by the temperature control. As a consequence, the difference ΔTU (signal 16) remains virtually unchanged on variation of the fuel 6 and/or fuel gas 6.

The medium is a fuel 6 and/or a fuel gas 6. The medium temperature TM is a temperature of the fuel 6 and/or of the fuel gas 6. A change in the medium temperature TM has no direct effect due to the difference formation relative to the measured value of the medium temperature TM. However, the change in medium temperature TM also has an effect on selected material constants, such as kinematic viscosity and/or the thermal conduction of the fuel 6 and/or fuel gas 6. Therefore, the change in medium temperature TM has an influence similar to that of a change in composition of the fuel 6 and/or fuel gas 6.

Like a change in fuel composition and/or fuel gas composition, a change in the temperature of the fuel 6 and/or fuel gas 6 therefore has no effect on the difference ΔTU (signal 41). The difference ΔTU (signal 16) is thus very largely independent of the temperature of the supplied fuel 6 and/or fuel gas 6. Within the wide range of fuel composition and/or fuel gas composition, the difference ΔTU (signal 16) is dependent only on the flow velocity or fuel supply 25 over the sensor element 21.

The mass flow sensor 11 with sensor element 21 may be installed in a fixed geometry with constant cross-sectional area. ΔTU (signal 16) is then very largely independent of fuel composition and/or fuel gas composition as well as very largely independent of fuel temperature and/or fuel gas temperature and only dependent on the mass flow rate of the fuel 6 or fuel gas 6.

The associated flow velocity and/or fuel supply and/or fuel gas supply is determined from ΔTU (signal 16) via the characteristic curve 41. The plot of a typical characteristic curve 41 is shown in FIG. 5. The value 40 here represents the flow velocity and/or fuel supply 25 for all temperatures and/or fuel compositions, calculated via the characteristic curve 41. The sensor monitoring unit 32 may determine the signal 16. The sensor monitoring unit 32 may transmit the signal 16 to the closed- and/or open-loop control unit 13. The flow signal 40 may be calculated via the characteristic curve 41 in the closed- and/or open-loop control unit 13. The flow signal 40 corresponds to the flow velocity 25 and/or fuel supply 6.

The characteristic curve 41 of signal 16 over signal 40 is uniquely defined on the basis of a flow calibration. The characteristic curve of signal 16 over signal 40 may be saved in the closed- and/or open-loop control unit 13. The characteristic curve of signal 16 over signal 40 may be saved in a nonvolatile memory of the closed- and/or open-loop control unit 13.

FIG. 6 shows three different diagrams for ΔTD (signal 17) over signal 42 in each case at different temperatures for different fuels 6 and/or fuel gases 6. Signal 42 represents the flow velocity 25 and/or fuel supply 6 but measured from the value ΔTD (signal 17). Dependency on fuel gas composition therefore stems from the fact that the heat from the heating resistor 26 does not solely reach the resistor element 28 via the thin layer and/or film 22. Instead, heat from the heating resistor 26 also reaches the resistor element 28 via the fuel 6 and/or the fuel gas 6. The temperature of the resistor element 28 is therefore also dependent on the substance parameters of the fuel 6 and/or fuel gas 6.

Characteristic curve 44 shows the behavior where methane is the fuel gas 6. This fuel gas 6 was here selected, by way of example, as reference. Characteristic curve 45 shows the behavior where the reference gas is methane with admixtures of higher-energy fuel gases 6, such as for example ethane or propane. Characteristic curve 46 shows the behavior of a fuel gas with admixtures for example of nitrogen as an inert gas. Characteristic curve 47 shows a mixture of methane as the fuel gas 6 with hydrogen, while characteristic curve 48 shows a characteristic curve for pure hydrogen and/or for pure hydrogen gas.

The fact that the substance parameters of the fuels 6 and/or fuel gases 6 are temperature-dependent leads overall to a temperature dependence for all fuel mixtures and/or fuel gas mixtures. In FIG. 6b, the characteristic curves of the described fuels 6 and/or fuel gases 6 are depicted for a reference temperature such as for example 293 kelvin.

FIG. 6a shows the corresponding characteristic curves for a lower temperature, while FIG. 6c shows the characteristic curves for a higher temperature. In the case of temperature compensation, the characteristic curves for a lower temperature or higher temperature are converted to the corresponding characteristic curves of the reference temperature.

This is achieved in the simplest case by shifting the characteristic curves on the basis of a fixed rule, which is established beforehand by laboratory measurements performed on the reference gas. The fixed rule may for example be saved in the closed- and open-loop control unit 13. The fixed rule may be saved in a nonvolatile memory of the closed- and open-loop control unit 13.

More complex calculation rules are also conceivable, for example interpolation between two saved characteristic curves at different temperatures for a reference gas. Temperature compensation proceeds by applying the characteristic curve compensation rule to a temperature difference ΔTD (signal 17). The ratios 44 to 48 between combustion fuels 6 and/or fuel gases 6 are maintained in the case of all conversions.

In some embodiments, conversion to the characteristic curves of the reference temperature is performed by a spiral similarity transformation. The spiral similarity transformation parameters are here established on the basis of measurements using reference gases. They may be saved in the nonvolatile memory of the closed- and/or open-loop control unit 13. The relationships may for example be established empirically in the laboratory using test specimens and are then valid for all sensor specimens.

In a further step, mapping of the respective temperature-compensated value onto the value for the reference gas is performed for various fuel gases, for example fuel gases 44 to 48. This is achieved here too in the simplest case by shifting the characteristic curves on the basis of a fixed rule, which is established beforehand by laboratory measurements performed on the reference gas.

In some embodiments, interpolation may be performed between in each case two characteristic curves. A spiral similarity transformation may be performed in which the characteristic curves for each selected fuel gas are mapped onto the characteristic curve of the reference gas. Here too, the rules for the individual fuel gases are saved for example in the closed- and/or open-loop control unit 13. The fixed rules may be saved in a nonvolatile memory of the closed- and/or open-loop control unit 13. Here too, they may for example be established empirically in the laboratory and are then valid for all sensor specimens.

The latter two steps may be performed in combination in a mapping step. In the case of spiral similarity transformation, a spiral similarity transformation which is a function of the fuel temperature is then obtained for each fuel gas 44 to 48. Here too, the rules may be saved in the closed- and/or open-loop control unit 13. The fixed rules may be saved in a nonvolatile memory of the closed- and/or open-loop control unit 13. All the relationships or mapping procedures may also be established empirically in the laboratory and are then valid for all sensor specimens.

Compensation in the form of a spiral similarity transformation also includes a calibration characteristic curve. The result of compensation including a calibration characteristic curve is the flow value 25 for the fuel supply 6 and/or for the fuel gas supply 6. In particular, the result of compensation including a calibration characteristic curve may be the flow value 25 of the fuel supply 6 and/or of the fuel gas supply 6.

The calibration characteristic curve indicates the relationship of the determined value ΔTD to the flow value 25 of the fuel supply 6 for the reference gas at reference temperature. The calibration characteristic curve does not contain fuel-specific properties or temperature dependence, but rather only the specific properties of a sensor specimen.

The temperature dependence of the fuel gas and the dependence of the fuel gas composition may be established empirically in the laboratory as substance parameters. Empirical establishment in the laboratory proceeds on a plurality of sensors irrespective of the sensor specimen. Mapping 41 may be saved as fixed mapping for each fuel gas composition and as a function of the medium temperature TM. The calibration characteristic curve with geometric properties has therefore to be established for just one fuel, namely for a reference fuel. The calibration characteristic curve with geometric properties has therefore to be established for just one gas, namely the reference gas.

Signal 42 is obtained from signal 17 as a result and/or starting point. Signal 42 is temperature-compensated. Signal 42 may be independent of the fuel composition and/or fuel gas composition. Signal 42 represents the flow velocity 25 converted to the reference fuel, calculated from the signal ΔTD (signal 17). For each fuel characteristic curve 44 to 48, a spiral similarity transformation as a function of fuel temperature is preferably saved to this end in the closed- and/or open-loop control unit 13. In addition to spiral similarity transformation, the calibration characteristic curve for TD is saved, e.g. in the closed- and/or open-loop control unit 13. The characteristic curve or parameters for the spiral similarity transformation or mapping for temperature and fuel gas compensation are preferably saved in a nonvolatile memory of the closed- and/or open-loop control unit 13. The calibration characteristic curve for each sensor specimen is likewise advantageously saved in a nonvolatile memory of the closed- and/or open-loop control unit 13. Signal 17 may be transmitted by the sensor monitoring unit 32 to the closed- and/or open-loop control unit 13.

As an alternative to the difference ΔTD (signal 17), derived values such as

$\Delta TDU=TD-TU$

may also be used. Similar values as in FIGS. 6a, 6b and 6c are then obtained. Mapping of the signal 17 onto the reference signal 42 proceeds in the same way. Mapping proceeds by way of the functions 44 to 48 established empirically for example for each fuel gas and the measured fuel gas temperature. Here too, the empirically established functions 44 to 48 are preferably saved in the nonvolatile memory of the closed- and/or open-loop control unit 13. Further, the calibration characteristic curve for the reference gas relative to the flow value 25 of the fuel supply 6 is preferably saved in the nonvolatile memory of the closed- and/or open-loop control unit 13.

The output value PH (signal 18) resulting from heat control is processed in the same way as signal 17 (signal ΔTD or signal ΔTDU). FIG. 7 shows plots of output values PH (signal 18) over the supply of fuel 6 and/or fuel gas 6 for three different fuel gas temperatures. The characteristic curves apply to the same fuel composition and/or fuel gas compositions as were described in relation to FIG. 6. FIG. 7b here shows the characteristic curves for an average temperature, which was selected as the reference temperature. The selected reference temperature may amount to 293 Kelvin, for example. FIG. 7a shows the characteristic curves for a lower fuel temperature and/or fuel gas temperature. FIG. 7a shows the characteristic curves for a higher fuel temperature and/or fuel gas temperature.

Temperature compensation to the reference temperature here proceeds most simply by factorial correction. In this case, a correction factor for various temperatures is captured in the laboratory. The correction factor may for example be saved in the sensor monitoring unit 32 or in the closed- and/or open-loop control unit 13. The correction factor may be saved in a nonvolatile memory of the sensor monitoring unit 32 or the closed- and/or open-loop control unit 13.

More complex rules for temperature compensation are possible, for instance using linear interpolation between two characteristic curves for different reference gas temperatures. The two characteristic curves may for example be saved in the closed- and/or open-loop control unit 13. The two characteristic curves may be saved in a nonvolatile memory of the closed- and/or open-loop control unit 13. Other more complex rules are possible, for instance rules which take account of signal 16.

A spiral similarity transformation is alternatively possible for temperature compensation. In the context of spiral similarity transformation, conversion also takes place on the basis of a calibration characteristic curve. The spiral similarity transformation parameters may be established using measurements with reference gases 49 to 53 from signal 18 to signal 43. They are preferably saved in the nonvolatile memory of the closed- and/or open-loop control unit 13. Temperature compensation proceeds by applying the characteristic curve compensation rule to the measured output value PH (signal 18). Here too, the relationships 49 to 53 may be established empirically in the laboratory using test specimens and are valid for all sensor specimens.

Characteristic curve 49 shows the behavior where methane is the fuel gas 6. This fuel gas 6 was here selected, by way of example, as reference. Characteristic curve 50 shows the behavior where the reference gas is methane with admixtures of higher-energy fuel gases 6, such as for example ethane or propane. Characteristic curve 51 shows the behavior of a fuel gas with admixtures for example of nitrogen as an inert gas. Characteristic curve 52 shows a mixture of methane as the fuel gas 6 with hydrogen, while characteristic curve 53 shows a characteristic curve for pure hydrogen.

In a further step, mapping of the respective temperature-compensated value onto the value for the reference gas is performed for various fuel gases, for example fuel gases 49 to 53. This is achieved here too in the simplest case by shifting the characteristic curves in accordance with a fixed rule, which is established beforehand by laboratory measurements performed on the reference gas.

In some embodiments, interpolation may be performed between in each case two characteristic curves. A spiral similarity transformation may be performed in which the characteristic curves for each selected fuel gas are mapped onto the characteristic curve of the reference gas. This compensation on the basis of a spiral similarity transformation conforms to the present thermal flow dynamic model of the sensor. Here too, the rules for the individual fuels and/or fuel gases are saved for example in the closed- and/or open-loop control unit 13. The fixed rules may be saved in a nonvolatile memory of the closed- and/or open-loop control unit 13. They may for example be established empirically in the laboratory and are then valid for all sensor specimens.

As with the signal ΔTU or ΔTDU, for the output value PH the latter two steps may performed in combination in a mapping step. In the case of spiral similarity transformation, a spiral similarity transformation as a function of the fuel temperature for each fuel gas 49 to 53 is then obtained. The mapping rules 49 to 53 for the output value are preferably saved in the closed- and/or open-loop control unit 13. The fixed mapping rules may be saved in a nonvolatile memory of the closed- and/or open-loop control unit 13. All the relationships or mapping steps 49 to 53 may be established by empirical measurements in the laboratory. They are then valid for all sensor specimens.

For a correct fuel and/or a correct fuel gas to be estimated, the characteristic curves 49 to 53 must correspond to the fuel gases 44 to 48. In other words, the fuel gas for characteristic curve 44 is the same as for characteristic curve 49 (here for example methane). The fuel gas for characteristic curve 45 is the same as for characteristic curve 50 (here for example methane with propane fraction). The fuel gas for characteristic curve 46 is the same as for characteristic curve 51 (here for example methane with nitrogen fraction). The fuel gas for characteristic curve 47 is the same as for characteristic curve 52 (here for example methane with hydrogen fraction). The fuel gas for characteristic curve 48 is the same as for characteristic curve 53 (here for example pure hydrogen). The characteristic curves 43 to 48 and 49 to 53 shown here may of course be extended with other characteristic curves for other fuel gas compositions.

For the purposes of compensation, a calibration characteristic curve for the output PH and/or the output value PH for the reference gas is saved here too, e.g. in the closed- and/or open-loop control unit 13. For the purposes in particular of spiral similarity transformation, a calibration characteristic curve for the output PH and/or the output value PH for the reference gas is saved, e.g. in the closed- and/or open-loop control unit 13. The characteristic curve or parameters for the spiral similarity transformation or mapping for temperature and fuel gas compensation may be saved for PH too in a nonvolatile memory of the closed- and/or open-loop control unit 13. Saving proceeds, for example in a nonvolatile memory of the closed- and/or open-loop control unit 13. The calibration characteristic curve for each sensor specimen may be saved in a nonvolatile memory of the closed- and/or open-loop control unit 13.

A value is obtained from

• • the measured signals 16 (for ΔTU), 17 (for ΔTD or ΔTDU) and 18 (for PH) and
  • the medium temperature TM
    for each fuel gas.

Said value corresponds to the respective measured value for ΔTU, ΔTD/ΔTDU and PH for the reference gas. The flow velocity/fuel gas supply 40, 42 and 43 may then be established for each fuel gas. This is established in each case on the basis of a calibration characteristic curve of the reference gas for ΔTU, ΔTD/ΔTDU and PH. In this case, the calibration characteristic curve or the characteristic calibration curves is/are individually established for each sensor specimen. If the respective fuel gas actual is actually flowing over the sensor 21, all three values 40, 42 and 43 correspond to the flow velocity 25. Said values 40, 42 and 43 also correspond to the fuel supply 6 and/or fuel gas supply 6.

If the fuel gas is known, one of the signals 16, 17 or 18 may be selected. On the basis of the medium temperature, the calibration characteristic curve and the known mapping rule 41 or 43 to 48 or 49 to 53, the value 40 or 42 or 43 is established. This is established on the assumption of a known fuel gas and/or a known fuel. Said value 40 or 42 or 43 is a measure of the flow velocity 25. The fuel supply may likewise be established in this way.

The signals 16, 17 or 18 differ with regard to quality, since they were captured using different sensors. Signal 16 (ΔTU) is very largely temperature-independent and over a wide range also independent of fuel gas a composition. Thus, using characteristic curve 41, the flow velocity 25 or fuel supply can be established for virtually all fuel gases and all fuel gas temperatures. Should a deviation exist for one or more special gases, different characteristic curves may here too be saved and selected in the closed- and/or open-loop control unit 13. This is described above for ΔTD.

Signal 17 (ΔTD or ΔTDU) is very precise for low flow values below 0.1 m/s to 20 m/s. In contrast, signal 18 (PH) has a wide measurement range, such that flow values of 0.5 m/s to 100 m/s can here be acquired sufficiently accurately. Signal 41, 42 or 43 may further be selected as a function of the established flow value. For instance, for low values, for example values below 5 m/s, signal 42 may be selected. For higher values, for example values greater than 5 m/s, signal 43 may be selected. It is conventional to build in hysteresis at the switch-over point. In other words, when approached from below, switch-over from signal 42 to signal 43 may be performed for example at 5.5 m/s or around 5.5 m/s. When approached from above, switch-over from signal 43 to signal 42 may be performed for example at or around 4.5 m/s.

It may be advantageous to capture air as a further gas and select it as reference gas. In this way, the calibration characteristic curve can be established very simply with air and the flow velocity of the fuel gas or the fuel supply can be established for each fuel gas on the basis of the respective mapping rule. Thus, if it is desired to set a sensor for a fuel gas, a mapping rule can be selected by the control program on selection of the fuel gas. The mapping rule may be saved in the nonvolatile memory of the closed- and/or open-loop control unit 13. The flow value 40 or 42 or 43 is determined from the measured value 16 or 17 or 18 and the calibration characteristic curve for the reference gas. This value 40 or 43 or 43 then corresponds to the correct flow velocity 25 or the correct fuel supply.

Furthermore, however, the gas composition may also be estimated for an unknown fuel gas. To this end, starting from signals 16 and/or 17 and/or 18, the flow value 40 is determined for each fuel gas composition using the mapping rule 41 and the reference characteristic curve. The reference characteristic curve is here such a characteristic curve of the calibration gas for ΔTU. All the flow values 42 for each fuel gas are further determined using all the assignments 44 to 48 and using the reference characteristic curve of the calibration gas for ΔTD/ΔTDU. The flow value 43 for each fuel gas is furthermore determined using all the assignments 49 to and 53 using the reference characteristic curve of the calibration gas for PH.

For each fuel gas, the difference between the established flow values (signal 40—signal 42) and (signal 40—signal 43) and (signal 42—signal 43) is then formed. The result is squared in each case. A sum of the squares σ is formed for each fuel and/or each fuel gas. The sum of the squares σ may be used as a measure for determining the gas composition by selecting the composition with the lowest value σ. The sum of the squares may be formed not only by simple summation but rather the individual squares may in each case be weighted by a factor prior to addition. This enables different influences of the fuel gas compositions on the signals 40, 42, 43 to be taken into account.

Using the selected gas composition, it is then possible to proceed by selecting one of the three selected values 40, 42 or 43 for the known gas composition. Here too, different result values 40, 42 or 43 may be selected as a function of the established value and here too a hysteresis is possible upon switch-over of the values. The square may also be formed for the values of the all gas compositions from just one difference. The sole difference is selected from one of the following differences:

• • signal 40—signal 42,
  • signal 40—signal 43,
  • signal 42—signal 43.

The measure σ for each gas composition then corresponds to the squared difference value of each gas composition.

Here too, the gas composition with the lowest value for σ is selected. Depending on the type of gas composition, an estimate from just one square difference may suffice. In general, however, better selectivity is achieved by using the difference of the sum of two or even three squared differences. The measurement and control unit 12 transmits signals 16 and/or 17 and or 18 to the closed- and/or open-loop control unit 13. The measurement and control unit 12 is in this case part of the mass flow sensor 11. In some embodiments, the measurement and control unit 12 may be integrated into the closed- and/or open-loop control unit 13.

Using the quantity of gas compositions and thus the quantity of mapping rules 41, 44 to 48 and 49 to 53 respectively, it is possible to select the fineness of the gas composition. To suppress noise, signals 16 and/or 17 and/or 18 may be averaged over a shorter or longer period. For this purpose, a short period may be considered to be 0.2 seconds. For this purpose, 5 seconds may be regarded as a recommended, longer period. For this purpose, a very long period may be considered to be 30 seconds or even 60 seconds.

On the basis of the selected gas composition, the gas mixture and thus the substance parameters of the selected fuel gas are known. The calorific value Hu and/or the minimum air requirement Lmin of the selected fuel gas are thus also known, for example. Like mapping rules 41, 44 to 48 and 49 to 53, the substance parameters, for example Hu and/or Lmin, may be saved in the closed- and/or open-loop control unit 13. They are assigned to a fuel gas. If the fuel gas was selected, the saved substance parameters, for example Hu and/or Lmin may also be selected, like the assignment. The substance parameters, for example Hu and/or Lmin, may be saved in the nonvolatile memory of the closed- and/or open-loop control unit 13.

The supply of fuel 6 and/or fuel gas 6 is corrected with the currently established correction factor of Hu in proportion to the correction factor under setting conditions. Correction may be performed by the closed- and/or open-loop control unit 13. To this end, the selected signal 40, 42 and/or 43 may be multiplied with the reciprocal of the currently established correction factor. The selected signal is in this case a measure of a flow velocity 25 and/or of the supply of fuel 6 and/or of the supply of fuel gas 6. Likewise, the setpoint for the supply of fuel 6 and/or of fuel gas 6 may be multiplied with the currently established correction factor. In general, the supply of fuel 6 and/or of fuel gas 6 is changed in proportion to the correction factor.

Thus, a fuel control circuit in the closed- and/or open-loop control unit 13 may correct the at least one fuel valve 7, 8. As a result of the correction, a correct supply of fuel 6 and/or of fuel gas 6 is set and/or adjusted. Thus, the power output of the combustion device 1 is also corrected.

The air supply may be corrected with the known, corrected supply of fuel 6 and/or of fuel gas 6 and its associated signal 16. A fuel-air ratio curve is used for correction. The fuel-air ratio curve may for example be saved in the closed- and/or open-loop control unit 13. The fuel-air ratio curve is advantageously saved in a nonvolatile memory of the closed- and/or open-loop control unit 13.

The closed- and/or open-loop control unit 13 changes the setpoint for the air supply 5 assigned in the fuel-air ratio curve using the currently established correction factor of Lmin in proportion to the correction factor under setting conditions. An air control circuit in this case corrects the air supply 5 by way of the motor-driven blower 3 and/or by way of the motor-driven air throttle valve 4. In some embodiments, the measured value for the air supply 5 may firstly be corrected. Thereafter, the supply of fuel 6 and/or of fuel gas 6 assigned by way of the fuel-air ratio is corrected, which leads to the same result.

For the purposes of the present disclosure, compensation of a first value as a function of a second value means that the influence of the second value on the first value is reduced and/or suppressed. In other words, the first value is compensated by the second value. This means that the first value is compensated as a function of the second value. The same is true in the case of dependencies of third and further values.

For the purposes of the present disclosure, compensability of a first value as a function of a second value means that the influence of the second value on the first value is reduced and/or suppressed. In other words, the first value is compensable by the second value. This means that the first value is compensable as a function of the second value. The same is true in the case of dependencies of third and further values.

In other words, the present disclosure describes methods for estimating a flow value (25) for fuels (6) and/or fuel gases (6) of different compositions which are supplied to a combustion device (1) via a fuel supply channel and/or fuel gas supply channel, wherein the combustion device (1) comprises a mass flow sensor (11), wherein the mass flow sensor (11) is in fluid connection with the fuel (6) and/or with the fuel gas (6), the method comprising: recording a first temperature signal, which indicates a first temperature of the fuel (6) and/or fuel gas (6), on the basis of a first resistor element (29) of the mass flow sensor (11); processing the first temperature signal to yield a first temperature (TM); determining a compensable value by recording a heat output signal, which indicates a heat output of a heating element (26) of the mass flow sensor (11); processing the heat output signal to yield a heat output; determining the compensable value as heat output; and estimating a flow value (25) for fuel supply and/or for fuel gas supply by compensation of the value compensable as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition on the basis of at least one saved mapping rule dependent on the first temperature (TM) and/or on the fuel composition and/or on the fuel gas composition and on the basis of a calibration characteristic curve saved for a reference gas.

Some embodiments include a method for estimating a type of fuel (6) and/or a type of fuel gas (6) in a combustion device (1) with a mass flow sensor (11), wherein the mass flow sensor (11) is in fluid connection with the fuel (6) and/or with the fuel gas (6), the method comprising: recording a heat output signal, which indicates a heat output of a heating element (26) of the mass flow sensor (11); recording a first temperature signal, which indicates a first temperature of the fuel (6) and/or fuel gas (6), on the basis of a first resistor element (29) of the mass flow sensor (11); recording a second temperature signal, which indicates a second temperature of the fuel (6) and/or fuel gas (6), on the basis of a second resistor element (27, 28) of the mass flow sensor (11), wherein the second resistor element (27, 28) different from is the first resistor element (29) and the second resistor element (27, 28) is arranged up- or downstream of heating element (26); processing the heat output signal to yield a heat output (PH), the first temperature signal to yield a first temperature (TM) and the second temperature signal to yield a second temperature (TD, TU); calculating a difference (ΔTD, ΔTU, ΔTDU) between the first and second temperatures; establishing a temperature-compensated heat output from the processed heat output (PH) and a temperature-compensated difference from the calculated difference (ΔTD, ΔTU, ΔTDU); and estimating the type of fuel (6) and/or the type of fuel gas (6) in the combustion device (1) as a function of the temperature-compensated heat output and the temperature-compensated difference.

In some embodiments, the mass flow sensor (11) is in contact with the fuel (6) and/or with the fuel gas (6).

The method for estimating a type of fuel (6) and/or a type of fuel gas (6) in a combustion device (1) with a mass flow sensor (11) may be used to determine a type of fuel (6) and/or a type of fuel gas (6) in a combustion device (1) with a mass flow sensor (11). The method may include determining the type of fuel (6) and/or the type of fuel gas (6) in the combustion device (1) as a function of the temperature-compensated heat output and the temperature-compensated difference.

The method for estimating a type of fuel (6) and/or a type of fuel gas (6) in a combustion device (1) with a mass flow sensor (11) me be used to calculate a type of fuel (6) and/or a type of fuel gas (6) in a combustion device (1) with a mass flow sensor (11). Accordingly, the method comprises calculating the type of fuel (6) and/or the type of fuel gas (6) in the combustion device (1) as a function of the temperature-compensated heat output and the temperature-compensated difference.

In some embodiments, the method includes recording a second temperature signal, which indicates a second temperature of the fuel (6) and/or fuel gas (6), on the basis of a second resistor element (27, 28) of the mass flow sensor (11), wherein the second resistor element (27, 28) is arranged up- or downstream of heating element (26), wherein a supply of fuel (6) and/or of fuel gas (6) to the combustion device (1) defines a direction of flow. The second temperature signal may be recorded simultaneously or substantially simultaneously with the first temperature signal.

In some embodiments, the method comprises: establishing the temperature-compensated heat output from the processed heat output (PH) on the basis of a first, empirically established calibration characteristic curve and/or on the basis of a first, empirically established calibration function; and establishing the temperature-compensated difference from the calculated difference (ΔTD, ΔTU, ΔTDU) on the basis of a second, empirically established calibration characteristic curve.

In some embodiments, the method comprises: establishing a first difference value of the established temperature-compensated difference from a temperature-compensated difference specified for a first fuel (6) and/or for a first fuel gas (6); establishing a second difference value of the established temperature-compensated difference from a temperature-compensated heat output specified for the first fuel (6) and/or for the first fuel gas (6); establishing a third difference value of the established temperature-compensated difference from a temperature-compensated difference specified for a second fuel (6) and/or for a second fuel gas (6); establishing a fourth difference value of the established temperature-compensated difference from a temperature-compensated heat output specified for the second fuel (6) and/or for the second fuel gas (6); establishing a first distance between the first and second difference values; establishing a second distance between the third and fourth difference values; and if the first distance is smaller than the second distance, estimating the type of fuel (6) and/or the type of fuel gas (6) in the combustion device (1) as the first fuel (6) and/or as the first fuel gas (6).

In some embodiments, the method comprises, if the first distance is smaller than the second distance, determining the type of fuel (6) and/or the type of fuel gas (6) in the combustion device (1) as the first fuel (6) and/or as the first fuel gas (6).

In some embodiments, the method comprises, if the second distance is smaller than the first distance, estimating the type of fuel (6) and/or the type of fuel gas (6) in the combustion device (1) as the second fuel (6) and/or as the second fuel gas (6).

In some embodiments, the method comprises: calculating a first difference value of the established temperature-compensated difference from a temperature-compensated difference specified for a first fuel (6) and/or for a first fuel gas (6); calculating a second difference value of the established temperature-compensated difference from a temperature-compensated heat output specified for the first fuel (6) and/or for the first fuel gas (6); calculating a third difference value of the established temperature-compensated difference from a temperature-compensated difference specified for a second fuel (6) and/or for a second fuel gas (6); and calculating a fourth difference value of the established temperature-compensated difference from a temperature-compensated heat output specified for the second fuel (6) and/or for the second fuel gas (6).

In some embodiments, the method comprises comparing the first distance with the second distance.

In some embodiments, the method comprises numerically comparing the first distance with the second distance.

In some embodiments, the method comprises, if the second distance is smaller than the first distance, determining the type of fuel (6) and/or the type of fuel gas (6) in the combustion device (1) as the second fuel (6) and/or as the second fuel gas (6).

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a minimum air requirement (Lmin); and controlling at least one air actuator (3, 4) of the combustion device (1) as a function of the assigned minimum air requirement (Lmin).

In some embodiments, the method comprises controlling at least one air actuator (3, 4) of the combustion device (1) to the assigned minimum air requirement (Lmin).

In some embodiments, the method comprises: assigning the determined type of fuel (6) and/or of fuel gas (6) to a minimum air requirement (Lmin); and controlling at least one air actuator (3, 4) of the combustion device (1) as a function of the assigned minimum air requirement (Lmin).

In some embodiments, the method comprises: assigning the calculated type of fuel (6) and/or of fuel gas (6) to a minimum air requirement (Lmin); and controlling at least one air actuator (3, 4) of the combustion device (1) as a function of the assigned minimum air requirement (Lmin).

In some embodiments, the method comprises: assigning the determined type of fuel (6) and/or of fuel gas (6) to a minimum air requirement (Lmin); t least one air actuator (3, 4) of the combustion device (1) to the assigned minimum air requirement (Lmin).

In some embodiments, the method comprises: assigning the calculated type of fuel (6) and/or of fuel gas (6) to a minimum air requirement (Lmin); and controlling at least one air actuator (3, 4) of the combustion device (1) to the assigned minimum air requirement (Lmin).

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); establishing a correction factor from the assigned calorific value (Hu) and a set calorific value of the combustion device (1); and correcting an air supply (5) of the combustion device (1) on the basis of at least one air actuator (3, 4) of the combustion device (1) or on the basis of the at least one air actuator (3, 4) of the combustion device (1) in proportion to the correction factor.

In some embodiments, the air supply (5) comprises an air supply (5) to a combustion chamber (2) of the combustion device (1).

In some embodiments, the method comprises: assigning the determined type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); establishing a correction factor from the assigned calorific value (Hu) and a set calorific value of the combustion device (1); and correcting an air supply (5) of the combustion device (1) on the basis of at least one air actuator (3, 4) of the combustion device (1) or on the basis of the at least one air actuator (3, 4) of the combustion device (1) in proportion to the correction factor.

In some embodiments, the method comprises: assigning the calculated type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); establishing a correction factor from the assigned calorific value (Hu) and a set calorific value of the combustion device (1); and correcting an air supply (5) of the combustion device (1) on the basis of at least one air actuator (3, 4) of the combustion device (1) or on the basis of the at least one air actuator (3, 4) of the combustion device (1) in proportion to the correction factor.

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); calculating a correction factor from the assigned calorific value (Hu) and a set calorific value of the combustion device (1); and correcting an air supply (5) of the combustion device (1) on the basis of at least one air actuator (3, 4) of the combustion device (1) or on the basis of the at least one air actuator (3, 4) of the combustion device (1) in proportion to the correction factor.

In some embodiments, the method comprises: assigning the determined type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); calculating a correction factor from the assigned calorific value (Hu) and a set calorific value of the combustion device (1); and correcting an air supply (5) of the combustion device (1) on the basis of at least one air actuator (3, 4) of the combustion device (1) or on the basis of the at least one air actuator (3, 4) of the combustion device (1) in proportion to the correction factor.

In some embodiments, the method comprises: assigning the calculated type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); calculating a correction factor from the assigned calorific value (Hu) and a set calorific value of the combustion device (1); and correcting an air supply (5) of the combustion device (1) on the basis of at least one air actuator (3, 4) of the combustion device (1) or on the basis of the at least one air actuator (3, 4) of the combustion device (1) in proportion to the correction factor.

In some embodiments, the method comprises: correcting an operating characteristic curve on the basis of the estimated type of fuel (6) and/or on the basis of the estimated type of fuel gas (6), wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply (16) and/or fuel gas supply (16), or a second operating characteristic curve between temperature-compensated difference and fuel supply (16) and/or fuel gas supply (16); determining a current fuel supply and/or a current fuel gas supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and controlling at least one fuel actuator (7, 8) of the combustion device (1) as a function of the current fuel supply and/or the current fuel gas supply.

In some embodiments, the further variable is selected from: the temperature-compensated heat output in the case of selection of the first operating characteristic curve as operating characteristic curve, or the temperature-compensated difference in the case of selection of the second operating characteristic curve as operating characteristic curve.

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); correcting an operating characteristic curve on the basis of the assigned calorific value (Hu), wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply (16) and/or fuel gas supply (16), or a second operating characteristic curve between temperature-compensated difference and fuel supply (16) and/or fuel gas supply (16); determining a current fuel supply and/or a current fuel gas supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and controlling at least one fuel actuator (7, 8) of the combustion device (1) as a function of the current fuel supply and/or the current fuel gas supply.

In some embodiments, the further variable is selected from: the temperature-compensated heat output in the case of selection of the first operating characteristic curve as operating characteristic curve, or the temperature-compensated difference in the case of selection of the second operating characteristic curve as operating characteristic curve.

Some embodiments include a combustion device (1) comprising a combustion chamber (2), a fuel supply channel for the supply of a fuel (6) and/or fuel gas (6) to the combustion chamber (2), a mass flow sensor (11) in or on the fuel supply channel and a closed- and/or open-loop control unit (13) in communicative connection with the mass flow sensor (11), wherein the mass flow sensor (11) comprises a heating element (26), a first resistor element (29) and a second resistor element (27, 28), wherein the second resistor element (27, 28) is different from the first resistor element (29), wherein the closed- and/or open-loop control unit (13) is configured: to record a heat output signal, which indicates a heat output of a heating element (26) of the mass flow sensor (11); to record a first temperature signal, which indicates a first temperature of the fuel (6) and/or fuel gas (6), on the basis of the first resistor element (29) of the mass flow sensor (11); to record a second temperature signal, which indicates a second temperature of the fuel (6) and/or fuel gas (6), on the basis of the second resistor element (27, 28); to process the heat output signal to yield a heat output (PH), the first temperature signal to yield a first temperature (TM) and the second temperature signal to yield a second temperature (TD, TU); to calculate a difference (ΔTD, ΔTU, ΔTDU) from the first and second temperatures; to establish a temperature-compensated heat output from the processed heat output (PH) and a temperature-compensated difference from the calculated difference (ΔTD, ΔTU, ΔTDU); and to estimate the type of fuel (6) and/or fuel gas (6) as a function of the temperature-compensated heat output and the temperature-compensated difference.

In some embodiments, the mass flow sensor (11) is in contact with the fuel (6) and/or the fuel gas (6). The mass flow sensor (11) is ideally in fluid connection with the fuel (6) and/or the fuel gas (6).

In some embodiments, a supply of fuel (6) and/or of fuel gas (6) through the fuel supply channel toward the combustion chamber (2) defines a direction of flow; and the second resistor element (27, 28) is arranged up- or downstream of heating element (26). The second temperature signal may be recorded simultaneously or substantially simultaneously with the first temperature signal.

In some embodiments, the type of fuel (6) and/or fuel gas (6) is determined. In some embodiments, the type of fuel (6) and/or fuel gas (6) is calculated.

In some embodiments, the closed- and/or open-loop control unit (13) has a nonvolatile memory and a first, empirically established calibration characteristic curve is saved in the nonvolatile memory of the closed- and/or open-loop control unit (13), wherein the closed- and/or open-loop control unit (13) is configured: to read in the first, empirically established calibration characteristic curve from the nonvolatile memory; and to establish the temperature-compensated heat output from the processed heat output (PH) on the basis of the first, empirically established calibration characteristic curve.

In some embodiments, the closed- and/or open-loop control unit (13) has a or the nonvolatile memory and a second, empirically established calibration characteristic curve is saved in the nonvolatile memory of the closed- and/or open-loop control unit (13), wherein the closed- and/or open-loop control unit (13) is configured: to read in the second, empirically established calibration characteristic curve from the nonvolatile memory; and to establish the temperature-compensated difference from the calculated difference (ΔTD, ΔTU, ΔTDU) on the basis of the second, empirically established calibration characteristic curve.

In some embodiments, the closed- and/or open-loop control unit (13) has a or the nonvolatile memory and a first, temperature-compensated difference specified for a first fuel (6) and/or for a first fuel gas (6) is saved in the nonvolatile memory of the closed- and/or open-loop control unit (13) and a second, temperature-compensated difference specified for a second fuel (6) and/or for a second fuel gas (6) is saved in the nonvolatile memory of the closed- and/or open-loop control unit (13) and a first, temperature-compensated heat output specified for the first fuel (6) and/or for the first fuel gas (6) is saved in the nonvolatile memory of the closed- and/or open-loop control unit (13) and a second, temperature-compensated heat output specified for the second fuel (6) and/or for the second fuel gas (6) is saved in the nonvolatile memory of the closed- and/or open-loop control unit (13), wherein the closed- and/or open-loop control unit (13) is configured: to establish a first difference value of the established temperature-compensated difference from the first, specified temperature-compensated difference; to establish a second difference value of the established temperature-compensated heat output from the first, specified temperature-compensated heat output; to establish a third difference value of the established temperature-compensated difference from the second, specified temperature-compensated difference; to establish a fourth difference value of the established temperature-compensated heat output from the second, specified temperature-compensated heat output; to establish a first distance between the first and second difference values; to establish a second distance between the third and fourth difference values; and if the first distance is smaller than the second distance, to estimate the type of fuel (6) and/or fuel gas (6) as the first fuel (6) and/or as the first fuel gas (6).

In some embodiments, the closed- and/or open-loop control unit (13) is configured, if the first distance is smaller than the second distance, to determine the type of fuel (6) and/or fuel gas (6) as the first fuel (6) and/or as the first fuel gas (6).

In some embodiments, the closed- and/or open-loop control unit (13) is configured, if the second distance is smaller than the first distance, to estimate the type of fuel (6) and/or fuel gas (6) as the second fuel (6) and/or as the second fuel gas (6). The first distance may be a first distance metric. The second distance may be a second distance metric.

In some embodiments, the closed- and/or open-loop control unit (13) is configured: to calculate a first difference value of the established temperature-compensated difference from the first, specified temperature-compensated difference; to calculate a second difference value of the established temperature-compensated heat output from the first, specified temperature-compensated heat output; to calculate a third difference value of the established temperature-compensated difference from the second, specified temperature-compensated difference; and to calculate a fourth difference value of the established temperature-compensated heat output from the second, specified temperature-compensated heat output.

In some embodiments, the first distance is established by addition of the first and second difference values. Accordingly, the second distance is established by addition of the third and fourth difference values. In some embodiments, the first distance is calculated by addition of the first and second difference values. Accordingly, the second distance is calculated by addition of the third and fourth difference values.

In some embodiments, the first distance is established as a function of a squared first difference value and as a function of a squared second difference value. Accordingly, the second distance is established as a function of a squared third difference value and as a function of a squared fourth difference value. In some embodiments, the first distance is calculated as a function of a squared first difference value and as a function of a squared second difference value. Accordingly, the second distance is calculated as a function of a squared third difference value and as a function of a squared fourth difference value.

In some embodiments, the first distance is established as the square root of a first sum, wherein the first sum is established by addition of a squared first difference value and a squared second difference value. The second distance is accordingly established as the square root of a second sum, wherein the second sum is established by addition of a squared third difference value and a squared fourth difference value. Ideally, the first distance is calculated as the square root of a first sum, wherein the first sum is calculated by addition of a squared first difference value and a squared second difference value. The second distance is accordingly calculated as the square root of a second sum, wherein the second sum is calculated by addition of a squared third difference value and a squared fourth difference value.

In some embodiments, the first fuel (6) and/or the first fuel gas (6) a first specified fuel (6) and/or a first specified fuel gas (6). The second fuel (6) and/or the second fuel gas (6) may be a second specified fuel (6) and/or a second specified fuel gas (6).

In some embodiments, the closed- and/or open-loop control unit (13) is configured to compare the first distance with the second distance.

In some embodiments, the closed- and/or open-loop control unit (13) is configured to compare the first distance with the second distance.

In some embodiments, the closed- and/or open-loop control unit (13) is configured, if the second distance is smaller than the first distance, to determine the type of fuel (6) and/or fuel gas (6) as the second fuel (6) and/or as the second fuel gas (6).

In some embodiments, the combustion device (1) comprises an air supply channel for an air supply (5) to the combustion chamber (2) and at least one air actuator (3, 4), which acts on the air supply channel, wherein the closed- and/or open-loop control unit (13) is in communicative connection with the at least one air actuator (3, 4) and is configured: to assign a minimum air requirement (Lmin) to the estimated type of fuel (6) and/or of fuel gas (6); and to control the at least one air actuator (3, 4) as a function of the assigned minimum air requirement (Lmin).

In some embodiments, the closed- and/or open-loop control unit (13) is configured to control the at least one air actuator (3, 4) in relation to the assigned minimum air requirement (Lmin).

In some embodiments, the closed- and/or open-loop control unit (13) is configured: to assign a minimum air requirement (Lmin) to the determined type of fuel (6) and/or of fuel gas (6); and to control the at least one air actuator (3, 4) as a function of the assigned minimum air requirement (Lmin).

In some embodiments, the closed- and/or open-loop control unit (13) is configured: to assign a minimum air requirement (Lmin) to the calculated type of fuel (6) and/or of fuel gas (6); and to control the at least one air actuator (3, 4) as a function of the assigned minimum air requirement (Lmin).

In some embodiments, the closed- and/or open-loop control unit (13) is configured: to assign a minimum air requirement (Lmin) to the determined type of fuel (6) and/or of fuel gas (6); and to control the at least one air actuator (3, 4) in relation to the assigned minimum air requirement (Lmin).

In some embodiments, the closed- and/or open-loop control unit (13) is configured: to assign a minimum air requirement (Lmin) to the calculated type of fuel (6) and/or of fuel gas (6); and to control the at least one air actuator (3, 4) in relation to the assigned minimum air requirement (Lmin).

In some embodiments, the combustion device (1) comprises a fuel supply channel for a fuel supply and/or a fuel gas supply to the combustion chamber (2) and at least one fuel actuator (7, 8), which acts on the fuel supply channel, wherein the closed- and/or open-loop control unit (13) is in communicative connection with the at least one fuel actuator (7, 8) and is configured: to correct an operating characteristic curve on the basis of the estimated type of fuel (6) and/or on the basis of the estimated type of fuel gas (6), wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply (16) and/or fuel gas supply (16), or a second operating characteristic curve between temperature-compensated difference and fuel supply (16) and/or fuel gas supply (16); to determine a current fuel supply and/or a current fuel gas supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and to control the at least one fuel actuator (7, 8) as a function of the current fuel supply and/or the current fuel gas supply.

In some embodiments, the further variable is selected from: the temperature-compensated heat output in the case of selection of the first operating characteristic curve as operating characteristic curve, or the temperature-compensated difference in the case of selection of the second operating characteristic curve as operating characteristic curve. In some embodiments, the fuel supply channel comprises a fuel gas supply channel.

In some embodiments, the combustion device (1) comprises a fuel supply channel for a fuel supply and/or a fuel gas supply to the combustion chamber (2) and at least one fuel actuator (7, 8), which acts on the fuel supply channel, wherein the closed- and/or open-loop control unit (13) is in communicative connection with the at least one fuel actuator (7, 8) and is configured: to assign a calorific value (Hu) to the estimated type of fuel (6) and/or to the estimated type of fuel gas (6); to correct an operating characteristic curve on the basis of the assigned calorific value (Hu), wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply (16) and/or fuel gas supply (16), or a second operating characteristic curve between temperature-compensated difference and fuel supply (16) and/or fuel gas supply (16); determining a current fuel supply and/or a current fuel gas supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and to control the at least one fuel actuator (7, 8) as a function of the current fuel supply and/or the current fuel gas supply.

In some embodiments, the further variable is selected from: the temperature-compensated heat output in the case of selection of the first operating characteristic curve as operating characteristic curve, or the temperature-compensated difference in the case of selection of the second operating characteristic curve as operating characteristic curve. In some embodiments, the fuel supply channel comprises a fuel gas supply channel.

The present disclosure also relates to a computer program product comprising commands which cause one of the above-stated combustion devices (1) to carry out one of the above-stated methods. The present disclosure relates, moreover, to a computer program product comprising commands which cause one of the above-stated combustion devices (1) with saved heat outputs for first and second fuels to carry out one of the above-stated methods while taking account of one or more distances.

Some embodiments include a method for estimating a flow value (25) for fuels (6) and/or fuel gases (6) of different compositions which are supplied to a combustion device (1) via a fuel supply channel and/or fuel gas supply channel, wherein the combustion device (1) comprises a mass flow sensor (11), wherein the mass flow sensor (11) is in fluid connection with the fuel (6) and/or with the fuel gas (6), the method comprising: recording a first temperature signal, which indicates a first temperature of the fuel (6) and/or fuel gas (6), on the basis of a first resistor element (29) of the mass flow sensor (11); processing the first temperature signal to yield a first temperature (TM); determining a compensable value either by recording a heat output signal, which indicates a heat output of a heating element (26) of the mass flow sensor (11); processing the heat output signal to yield a heat output; determining the compensable value as heat output; or by recording a second temperature signal, which indicates a second temperature of the fuel (6) and/or fuel gas (6), on the basis of a second resistor element (27, 28) of the mass flow sensor (11), and/or recording a third temperature signal, which indicates a third temperature of the fuel (6) and/or fuel gas (6), on the basis of a third resistor element (28, 27) of the mass flow sensor (11), wherein the second and/or the third resistor element is different from the first resistor element (29); processing the second temperature signal to yield a second temperature (TD, TU) and/or the third temperature signal to yield a third temperature (TU, TD); determining the compensable value as the first temperature difference (ΔTD, ΔTU, ΔTDU) between two different, preferably mutually different, temperatures, selected from: the first temperature (TM), the second temperature (TD, TU), the third temperature (TU, TD); and estimating a flow value (25) for fuel supply (6) and/or for fuel gas supply (6) by compensation of the value compensable as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition on the basis of at least one saved mapping rule dependent on the first temperature (TM) and/or on the fuel composition and/or on the fuel gas composition and on the basis of a calibration characteristic curve saved for a reference gas.

In some embodiments, the second and/or third resistor element is arranged up- or downstream of a or the heating element (26). In some embodiments, the first resistor element (29) of the mass flow sensor (11) comprises a first electrical resistor, for example a first electrical, ohmic resistor. In one specific embodiment, the first resistor element (29) of the mass flow sensor (11) is a first electrical resistor, for example a first electrical, ohmic resistor. In some embodiments, the second resistor element (27, 28) of the mass flow sensor (11) comprises a second electrical resistor, for example a second electrical, ohmic resistor. In some embodiments, the second resistor element (27, 28) of the mass flow sensor (11) is a second electrical resistor, for example a second electrical, ohmic resistor. In some embodiments, the third resistor element (27, 28) of the mass flow sensor (11) comprises a third electrical resistor, for example a third electrical, ohmic resistor. In some embodiments, the third resistor element (27, 28) of the mass flow sensor (11) is a third electrical resistor, for example a third electrical, ohmic resistor.

In particular, the present disclosure relates to estimating a flow value (25) for the fuel supply (6) and/or for the fuel gas supply (6) by compensating the value compensable as a function of the first temperature (TM) and as a function of at least one first variable selected from: the fuel composition, the fuel gas composition, on the basis of at least one saved mapping rule dependent on the first temperature (TM) and on at least one second variable selected from: the fuel composition, the fuel gas composition, and on the basis of a calibration characteristic curve saved for a reference gas.

The present disclosure further relates to one of the above-stated methods comprising determining the compensable value as a first temperature difference (ΔTD, ΔTU, ΔTDU) between the first (TM) and the second temperature (TD, TU) or as a temperature difference (ΔTD, ΔTU, ΔTDU) between the second and third temperatures (TU, TD).

The present disclosure furthermore relates to one of the above-stated methods comprising 0 determining the compensable value as the first temperature difference (ΔTD, ΔTU, ΔTDU) between two different temperatures, selected exclusively from: the first temperature (TM), the second temperature (TD, TU), and the third temperature (TU, TD).

In the context of this disclosure, an exclusive function is a function which is dependent exclusively on the stated arguments. In other words, the list of arguments of a function is definitive. The same applies to an exclusive selection.

The present disclosure teaches one of the above-stated methods, wherein the reference gas for the calibration characteristic curve is methane gas. A flow value (25) of the fuel supply (6) and/or of the fuel gas supply (6) may be estimated.

The present disclosure furthermore teaches one of the above-stated methods, wherein the reference gas for the calibration characteristic curve is air.

The present disclosure further teaches one of the above-stated methods, wherein the combustion device (1) comprises a closed- and/or open-loop control unit (13), the method comprising saving the calibration characteristic curve in the closed- and/or open-loop control unit (13).

The present disclosure moreover teaches one of the above-stated methods, wherein the combustion device (1) comprises a closed- and/or open-loop control unit (13) with an operator control unit and wherein a plurality of mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) are saved in the closed- and/or open-loop control unit (13), the method comprising, on setting the combustion device (1), selecting the saved rule, dependent on the first temperature (TM), from the plurality of mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) on setting the combustion device (1), with the assistance of the operator control unit.

The present disclosure additionally teaches one of the above-stated methods, wherein the combustion device (1) comprises a closed- and/or open-loop control unit (13) with an operator control unit and wherein a plurality of mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM), are saved in the closed- and/or open-loop control unit (13), the method comprising, on starting up the combustion device (1), selecting the saved mapping rule, dependent on the first temperature (TM), from the plurality of mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) on setting the combustion device (1), with the assistance of the operator control unit.

The present disclosure additionally teaches one of the above-stated methods, wherein the combustion device (1) comprises a closed- and/or open-loop control unit (13) with an operator control unit and wherein a plurality of mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) are saved in the closed- and/or open-loop control unit (13), the method comprising, on servicing the combustion device (1), selecting the saved mapping rule, dependent on the first temperature (TM), from the plurality of mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) on setting the combustion device (1), with the assistance of the operator control unit.

In some embodiments, the dependent mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) in each case comprise a saved calibration characteristic curve and/or in each case comprise a modeling function.

In some embodiments, the combustion device (1) comprises a closed- and/or open-loop control unit (13) and a plurality of first mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) and a plurality of second mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) are saved in the closed- and/or open-loop control unit (13), the method comprising: recording the heat output signal, which indicates a heat output of a heating element (26) of the mass flow sensor (11); processing the heat output signal to yield the heat output; establishing a plurality of first estimated flow values (25) for the fuel supply and/or for the fuel gas supply by compensating the heat output as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of first, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a first, saved calibration characteristic curve; recording a second temperature signal and/or a third temperature signal; processing the second temperature signal to yield a second temperature (TD, TU) and/or the third temperature signal to yield a third temperature (TU, TD); determining the temperature difference (ΔTD, ΔTU, ΔTDU) between two different temperatures selected from: the first temperature (TM), the second temperature (TD, TU), and the third temperature (TU, TD); establishing a plurality of second estimated flow values (25) for the fuel supply and/or for the fuel gas supply by compensating the temperature difference (ΔTD, ΔTU, ΔTDU) as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of second, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a second, saved calibration characteristic curve; and estimating the type of fuel (6) and/or of fuel gas (6) on the basis of the plurality of first estimated flow values (25) and on the basis of the plurality of second estimated flow values (25).

In some embodiments, the combustion device (1) comprises a closed- and/or open-loop control unit (13) and a plurality of first mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) and a plurality of second mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) are saved in the closed- and/or open-loop control unit (13), the method comprising the following steps: recording the heat output signal, which indicates a heat output of a heating element (26) of the mass flow sensor (11); processing the heat output signal to yield the heat output; establishing a plurality of first estimated flow values (25) for the fuel supply (6) and/or for the fuel gas supply (6) by compensating the heat output as a function of the first temperature (TM) and as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of first, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a first, saved calibration characteristic curve; recording the second temperature signal and/or the third temperature signal; processing the second temperature signal to yield a second temperature (TD, TU) and/or the third temperature signal to yield a third temperature (TU, TD); determining the temperature difference (ΔTD, ΔTU, ΔTDU) between two different temperatures selected from: the first temperature (TM), the second temperature (TD, TU), and the third temperature (TU, TD); establishing a plurality of second estimated flow values (25) for the fuel supply (6) and/or for the fuel gas supply (6) by compensating the temperature difference (ΔTD, ΔTU, ΔTDU) as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of second, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a second, saved calibration characteristic curve; and estimating the type of fuel (6) and/or of fuel gas (6) on the basis of the plurality of first estimated flow values (25) and on the basis of the plurality of second estimated flow values (25).

Provision may in particular be made for a plurality of second estimated flow values (25) for the fuel supply (6) and/or for the fuel gas supply (6) to be established by compensating the temperature difference (ΔTD, ΔTU, ΔTDU) as a function of the first temperature (TM) and as a function of a third variable selected from: the fuel composition, and the fuel gas composition, on the basis of at least one mapping rule of the plurality of second, saved mapping rule (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a second, saved calibration characteristic curve.

In some embodiments, the combustion device (1) comprises a closed- and/or open-loop control unit (13) and a plurality of first mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) and a plurality of second mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM) are saved in the closed- and/or open-loop control unit (13), the method comprising: recording the heat output signal, which indicates a heat output of a heating element (26) the mass flow sensor (11); processing the heat output signal to yield the heat output; establishing a plurality of first estimated flow values (25) for the fuel supply (6) and/or for the fuel gas supply (6) by compensating the heat output as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of each mapping rule of the plurality of first, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a first, saved calibration characteristic curve; recording the second temperature signal and/or the third temperature signal; processing the second temperature signal to yield a second temperature (TD, TU) and/or the third temperature signal to yield a third temperature (TU, TD); determining the temperature difference (ΔTD, ΔTU, ΔTDU) between two different temperatures selected d from: the first temperature (TM), the second temperature (TD, TU), and the third temperature (TU, TD); establishing a plurality of second estimated flow values (25) for the fuel supply (6) and/or for the fuel gas supply (6) by compensating the temperature difference (ΔTD, ΔTU, ΔTDU) as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of each mapping rule of the plurality of second, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a second, saved calibration characteristic curve; and estimating the type of fuel (6) and/or of fuel gas (6) on the basis of the plurality of first estimated flow values (25) and on the basis of the plurality of second estimated flow values (25).

In some e embodiments, the method comprises determining the temperature difference (ΔTD, ΔTU, ΔTDU) between two different temperatures selected exclusively from: the first temperature (TM), the second temperature (TD, TU), and the third temperature (TU, TD).

In some embodiments, the method comprises: forming distances between flow values of the plurality of first estimated flow values (25) and the plurality of second estimated flow values (25); selecting the smallest distance from the distances formed; and estimating the type of fuel (6) and/or of fuel gas (6) by assigning the smallest distance to a fuel (6) and/or to a fuel gas (6).

In some embodiments, the distances formed are differences formed or differential amounts formed.

In some embodiments, the method comprises: forming differential amounts between flow values of the plurality of first estimated flow values (25) and the plurality of second estimated flow values (25); selecting the smallest differential amount from the differential amounts formed; and estimating the type of fuel (6) and/or of fuel gas (6) by assigning the smallest differential amount to a fuel (6) and/or to a fuel gas (6).

In some embodiments, a plurality of third mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM), are saved in the closed- and/or open-loop control unit (13), the method comprises: recording a fourth temperature signal, which indicates a fourth temperature of the fuel (6) and/or fuel gas (6), on the basis of a fourth resistor element (28, 27) of the mass flow sensor (11), wherein the fourth resistor element (28, 27) is different from the first resistor element (29) and from the second resistor element (27, 28) and wherein the fourth resistor element (28, 27) is arranged opposite the second resistor element (27, 28) up- or downstream relative to the heating element (26); processing the fourth temperature signal to yield a fourth temperature (TU, TD); calculating a second temperature difference (ΔTD, ΔTU, ΔTDU) between two different, preferably mutually different, temperatures, selected from: the first temperature (TM), the second temperature (TD, TU), and the fourth temperature (TU, TD); establishing a plurality of third estimated flow values (25) for the fuel supply (6) and/or for the fuel gas supply (6) by compensating the second temperature difference (ΔTD, ΔTU, ΔTDU) as a function of the first temperature (TM) and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of third, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a third, saved calibration characteristic curve; and; estimating the type of fuel (6) and/or of fuel gas (6) on the basis of the plurality of first estimated flow values (25) and on the basis of the plurality of second estimated flow values (25) and/or on the basis of the basis of the plurality of third estimated flow values (25).

In some embodiments, the method comprises calculating a second temperature difference (ΔTD, ΔTU, ΔTDU) between two different, preferably mutually different, temperatures, selected exclusively from: the first temperature (TM), the second temperature (TD, TU), and the fourth temperature (TU, TD).

In some embodiments, the fourth resistor element (27, 28) of the mass flow sensor (11) comprises a fourth electrical resistor, for example a fourth electrical, ohmic resistor. In some embodiments, the fourth resistor element (27, 28) of the mass flow sensor (11) is a fourth electrical resistor, for example a fourth electrical, ohmic resistor. The fourth temperature signal may further be identical to the third temperature signal. On the other hand, the fourth temperature signal and the third temperature signal may also be different.

In some embodiments, a plurality of third mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) for selectable fuels (6) and/or for selectable fuel gases (6) and dependent on the first temperature (TM), are saved in the closed- and/or open-loop control unit (13), the method comprising: recording a fourth temperature signal, which indicates a fourth temperature of the fuel (6) and/or fuel gas (6), on the basis of a fourth resistor element (28, 27) of the mass flow sensor (11), wherein the fourth resistor element (28, 27) is different from the first resistor element (29) and from the second resistor element (27, 28) and wherein the fourth resistor element (28, 27) is arranged opposite the second resistor element (27, 28) up- or downstream relative to the heating element (26); processing the fourth temperature signal to yield a fourth temperature (TU, TD); calculating a second temperature difference (ΔTD, ΔTU, ΔTDU) between two different, preferably mutually different, temperatures, selected from: the first temperature (TM), the second temperature (TD, TU), and the fourth temperature (TU, TD); establishing a plurality of third estimated flow for the fuel supply (6) and/or for the fuel gas values (25) supply (6) by compensating the second temperature difference (ΔTD, ΔTU, ΔTDU) as a function of the first temperature (TM) and/or of the fuel composition and/or of the fuel gas composition, on the basis of each mapping rule of the plurality of third, saved mapping rules (40, 44/49, 45/50, 46/51, 47/52, 48/53) and on the basis of a third, saved calibration characteristic curve; and estimating the type of fuel (6) and/or of fuel gas (6) on the basis of the plurality of first estimated flow values (25) and on the basis of the plurality of second estimated flow values (25) and on the basis of the basis of the plurality of third estimated flow values (25).

In some embodiments, the method comprises calculating a second temperature difference (ΔTD, ΔTU, ΔTDU) between two different, preferably mutually different, temperatures, selected exclusively from: the first temperature (TM), second temperature (TD, TU), and the fourth temperature (TU, TD).

In some embodiments, the method comprises: forming first differences between flow values of the plurality of first estimated flow values (25) and the plurality of second estimated flow values (25); forming first squared differences by squaring the first differences; forming second differences between flow values of the plurality of first estimated flow values (25) and the plurality of third estimated flow values (25); forming second squared differences by squaring the second differences; forming third differences between flow values of the plurality of second estimated flow values (25) and the plurality of third estimated flow values (25); forming third squared differences by squaring the third differences; forming sum values by summing in each case a first squared difference selected from the first squared differences formed, in each case a second squared difference selected from the second squared differences formed and in each case a third squared difference selected from the third squared differences formed; selecting the smallest sum value from the sum values formed; and estimating the type of fuel (6) and/or of fuel gas (6) by assigning the smallest sum value to a fuel (6) and/or to a fuel gas (6).

In some embodiments, the method comprises: forming first distances between flow values of the plurality of first estimated flow values (25) and the plurality of second estimated flow values (25); forming first squared distances by squaring the first distances; forming second distances between flow values of the plurality of first estimated flow values (25) and the plurality of third estimated flow values (25); forming second squared distances by squaring the second distances; forming third distances between flow values of the plurality of second estimated flow values (25) and the plurality of third estimated flow values (25); forming third squared distances by squaring the third distances; forming sum values by summing in each case a first squared distance selected from the first squared distances formed, in each case a second squared distance selected from the second squared distances formed and in each case a third squared distance selected from the third squared distances formed; selecting the smallest sum value from the sum values formed; and estimating the type of fuel (6) and/or of fuel gas (6) by assigning the smallest sum value to a fuel (6) and/or to a fuel gas (6).

In some embodiments, the first, second and third distances are first, second and third differences. In some embodiments, the first, second and third distances are first, second and third differential amounts.

In some embodiments, the method comprises selecting a value as a measure of a flow of the fuel (6) or fuel gas (6) from the plurality of first estimated flow values (25) and from the plurality of second estimated flow values (25).

In some embodiments, the method comprises selecting a value as a measure of a flow of the fuel (6) or fuel gas (6) from the plurality of first estimated flow values (25) and from the plurality of second estimated flow values (25) as a function of numerical values of the first estimated flow values (25) from the plurality of first estimated flow values (25) and as a function of numerical values of the second estimated flow values (25) from the plurality of second estimated flow values (25).

In some embodiments, the method comprises saving the mapping rule dependent on the first temperature (TM) in the closed- and/or open-loop control unit (13).

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a minimum air requirement (Lmin); and controlling at least one air actuator (3, 4) of the combustion device (1) as a function of the assigned minimum air requirement (Lmin).

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); establishing a correction factor from the assigned calorific value (Hu) and a set calorific value of the combustion device (1); and correcting an air supply (5) of the combustion device (1) on the basis of at least one air actuator (3, 4) of the combustion device (1) or on the basis of the at least one air actuator (3, 4) of the combustion device (1) in proportion to the correction factor.

Correcting an air supply (5) of the combustion device (1) on the basis of at least one air actuator (3, 4) of the combustion device (1) in proportion to the correction factor comprises correcting the air supply (5) of the combustion device (1) on the basis of the at least one air actuator (3, 4) of the combustion device (1) by forming a ratio, wherein the correction factor enters into the ratio. In other words, the ratio formed is a function of the correction factor. The ratio may in particular be a quotient.

In some embodiments, the method comprises: correcting an operating characteristic curve on the basis of the estimated type of fuel (6) and/or on the basis of the estimated type of fuel gas (6), wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply (16) and/or fuel gas supply (16), or a second operating characteristic curve between temperature-compensated difference and fuel supply (16) and/or fuel gas supply (16); determining a current fuel supply and/or a current fuel gas supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and controlling at least one fuel actuator (7, 8) of the combustion device (1) as a function of the current fuel supply and/or the current fuel gas supply.

In some embodiments, the method comprises: assigning the estimated type of fuel (6) and/or of fuel gas (6) to a calorific value (Hu); correcting an operating characteristic curve on the basis of the assigned calorific value (Hu), wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply (16) and/or fuel gas supply (16), or a second operating characteristic curve between temperature-compensated difference and fuel supply (16) and/or fuel gas supply (16); determining a current fuel supply and/or a current fuel gas supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and controlling at least one fuel actuator (7, 8) of the combustion device (1) as a function of the current fuel supply and/or the current fuel gas supply.

In some embodiments, a combustion device (1) comprises a combustion chamber (2), a fuel supply channel for the supply of a fuel (6) and/or fuel gas (6) to the combustion chamber (2), a mass flow sensor (11) in or on the fuel supply channel and a closed- and/or open-loop control unit (13) in communicative connection with the mass flow sensor (11); wherein the mass flow sensor (11) comprises a heating element (26), a first resistor element (29) and a second resistor element (27, 28) and/or a third resistor element (28, 27), wherein the second and/or third resistor element is different from the first resistor element (29) and the second and/or third resistor element is arranged up- or downstream of heating element (26); wherein the mass flow sensor (11) comprises a fourth resistor element (28, 27), wherein the fourth resistor element (28, 27) is different from the first resistor element (29) and from the second resistor element (27, 28); the second resistor element (27, 28) and the fourth resistor element (28, 27) are arranged opposingly up- or downstream relative to the heating element (26); and the closed- and/or open-loop control unit (13) is configured to carry out one of the above-stated methods.

In some embodiments, a combustion device (1) comprises a combustion chamber (2), a fuel supply channel for the supply of a fuel (6) and/or fuel gas (6) to the combustion chamber (2), a mass flow sensor (11) in or on the fuel supply channel and a closed- and/or open-loop control unit (13) in communicative connection with the mass flow sensor (11); wherein the mass flow sensor (11) comprises a heating element (26), a first resistor element (29) and a second resistor element (27, 28) different from the first resistor element (29) and arranged up- or downstream of heating element (26), and/or a third resistor element (28, 27) different from the first resistor element (29) arranged up- or downstream of heating element (26) and/or a fourth resistor element (28, 27) different from the first (29) and second (27, 28) resistor elements and up- or downstream of heating element (26) opposingly relative to the second resistor element (27, 28), wherein the closed- and/or open-loop control unit (13) is configured to carry out one of the above-stated methods.

In some embodiments, a combustion device (1) comprises a combustion chamber (2), a fuel supply channel for the supply of a fuel (6) and/or fuel gas (6) to the combustion chamber (2), a mass flow sensor (11) in or on the fuel supply channel and a closed- and/or open-loop control unit (13) in communicative connection with the mass flow sensor (11); wherein the mass flow sensor (11) comprises a heating element (26), a first resistor element (29) and a second resistor element (27, 28) different from the first resistor element (29) and arranged up- or downstream of heating element (26), and/or a third resistor element (28, 27) different from the first resistor element (29) arranged up- or downstream of heating element (26) and/or a fourth resistor element (28, 27) different from the first (29) and second (27, 28) resistor elements and arranged up- or downstream relative to heating element (26) opposingly relative to the second resistor element (27, 28), wherein the closed- and/or open-loop control unit (13) is configured to carry out one of the above-stated methods.

In some embodiments, the closed- and/or open-loop control units (13) of the above-stated combustion devices (1) may comprise an operator control unit, for example a screen and a keyboard. Such devices (1) are for example suitable for carrying out a method including the operator control unit.

In some embodiments, the fourth resistor element (28, 27) is identical to the third resistor element (28, 27). In another embodiment, the fourth resistor element (28, 27) and the third resistor element (28, 27) are different.

In some embodiments, a computer program product comprises commands which cause the above-stated combustion device (1) to carry out elements of one or more of the methods described herein. In some embodiments, a computer program product comprises commands which cause a closed- and/or open-loop control unit of one of the above-stated combustion devices (1) to carry out one or more of the elements according to an above-stated method.

The above relates to individual embodiments of the disclosure. The embodiments can be modified in various ways without deviating from the underlying concept and without going beyond the scope of this disclosure. The subject matter of the present disclosure is defined by the claims thereof. Very wide-ranging modifications can be made without going beyond the scope of protection of the following claims.

REFERENCE CHARACTERS

• • 1: Combustion device
  • 2: Combustion chamber
  • 3: Blower
  • 4: Throttle valve
  • 5: Air supply
  • 6: Fuel and/or fuel gas
  • 7, 8: Fuel valves
  • 9: Flue
  • 10: Air supply channel
  • 11: Mass flow sensor
  • 12: Measurement and control unit
  • 13: Closed- and/or open-loop control unit
  • 14: Control signal for air throttle valve
  • 15: Control signal for motor-driven blower
  • 16: Differential temperature ΔTU
  • 17: Differential temperature ΔTD or ΔTDU
  • 18: Heat output PH of the mass flow sensor
  • 19, 20: Control signals for motor-driven fuel valves
  • 21: Sensor element
  • 22: Thin layer and/or film
  • 23, 24: Areas
  • 25: Flow velocity
  • 26-29: Resistor elements
  • 30: Reference resistor
  • 31: Series resistor
  • 32: Sensor monitoring unit
  • 33: Driver
  • 34-39: Electrical voltages
  • 40: Flow signal, calculated from ΔTU
  • 41: Assignment, characteristic curve between ΔTU and fuel gas flow
  • 42: Flow signal, calculated from ΔTD or ΔTDU
  • 43: Flow signal, calculated from heat output PH
  • 44-48: Assignments, characteristic curves between ΔTD/ΔTDU and fuel gas flow for various gas compositions
  • 49-53: Assignments, characteristic curves between ΔTD/ΔTDU and fuel gas flow for various gas compositions

Claims

1. A method for estimating a flow value for fuels of different compositions supplied to a combustion device via a fuel supply channel, wherein the combustion device comprises a mass flow sensor in fluid connection with the fuel, the method comprising:

recording a first temperature signal indicating a first temperature of the fuel using a first resistor element of the mass flow sensor;

processing the first temperature signal to yield a first temperature;

determining a compensable value by recording a heat output signal indicating a heat output of a heating element of the mass flow sensor;

processing the heat output signal to yield a heat output;

determining the compensable value as heat output; and

estimating a flow value for the fuel supply by compensation of the value compensable as of a function the first temperature and/or as a function of the fuel composition and/or as a function of the fuel gas composition on the basis of at least one saved mapping rule dependent on the first temperature and/or on the fuel composition and/or on the fuel gas composition and on the basis of a calibration characteristic curve saved for a reference gas.

2. The method as claimed in claim 1, wherein:

the combustion device comprises a closed- and/or open-loop control unit and a plurality of first mapping rules for selectable fuels and dependent on the first temperature and a plurality of second mapping rules for selectable fuels and dependent on the first temperature are saved in the closed- and/or open-loop control unit, the method comprising:

establishing a plurality of first estimated flow values for the fuel supply by compensating the heat output as a function of the first temperature and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of first, saved mapping rules and saved a first, calibration characteristic curve;

recording a second temperature signal and/or a third temperature signal;

processing the second temperature signal to yield a second temperature and/or the third temperature signal to yield a third temperature;

determining the temperature difference between two different temperatures selected from: the first temperature, the second temperature, and the third temperature;

establishing a plurality of second estimated flow values supply by compensating for the fuel the temperature difference as a function of the first temperature and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of second, saved mapping rules and a second, saved calibration characteristic curve; and

estimating the type of fuel on the basis of the plurality of first estimated flow values and the plurality of second estimated flow values.

3. The method as claimed in claim 2, the method comprising:

forming distances between flow values of the plurality of first estimated flow values and the plurality of second estimated flow values;

selecting the smallest distance from the distances formed; and

estimating the type of fuel by assigning the smallest distance to a fuel.

4. The method as claimed in claim 2, wherein a plurality of third mapping rules for selectable fuels and dependent on the first temperature are saved in the closed- and/or open-loop control unit, the method comprising:

recording a fourth temperature signal indicating a fourth temperature of the fuel on the basis of a fourth resistor element of the mass flow sensor, wherein the fourth resistor element is different from the first resistor element and from the second resistor element and wherein the fourth resistor element is arranged opposite the second resistor element;

processing the fourth temperature signal to yield a fourth temperature;

calculating a second temperature difference between two different temperatures, selected from: the first temperature, the second temperature, and the fourth temperature;

establishing a plurality of third estimated flow values for the fuel supply by compensating the second temperature difference as a function of the first temperature and/or as a function of the fuel composition and/or as a function of the fuel gas composition, on the basis of at least one mapping rule of the plurality of third, saved mapping rules and on the basis of a third, saved calibration characteristic curve; and

estimating the type of fuel on the basis of the plurality of first estimated flow values and on the basis of the plurality of second estimated flow values and/or on the basis of the basis of the plurality of third estimated flow values.

5. The method as claimed in claim 4, the method comprising:

forming first distances between flow values of the plurality of first estimated flow values and the plurality of second estimated flow values;

forming first squared distances by squaring the first distances;

forming second distances between flow values of the plurality of first estimated flow values and the plurality of third estimated flow values;

forming second squared distances by squaring the second distances;

forming third distances between flow values of the plurality of second estimated flow values and the plurality of third estimated flow values;

forming third squared distances by squaring the third distances;

forming sum values by summing in each case a first squared distance selected from the first squared distances formed, in each case a second squared distance selected from the second squared distances formed and in each case a third squared distance selected from the third squared distances formed;

selecting the smallest sum value from the sum values formed; and

estimating the type of fuel by assigning the smallest sum value to a fuel.

6. The method as claimed in claim 2, the method comprising selecting a value as a measure of a flow of the fuel from the plurality of first estimated flow values and from the plurality of second estimated flow values.

7. The method as claimed in claim 6, the method comprising selecting a value as a measure of a flow of the fuel from the plurality of first estimated flow values and from the plurality of second estimated flow values as a function of numerical values of the first estimated flow values from the plurality of first estimated flow values and numerical values of the second estimated flow values from the plurality of second estimated flow values.

8. The method as claimed in claim 2, the method comprising:

assigning the estimated type of fuel to a minimum air requirement; and

controlling at least one air actuator of the combustion device as a function of the assigned minimum air requirement.

9. The method as claimed in claim 2, the method comprising:

assigning the estimated type of fuel to a calorific value;

establishing a correction factor from the assigned calorific value and a set calorific value of the combustion device; and

correcting an air supply of the combustion device on the basis of at least one air actuator of the combustion device or on the basis of the at least one air actuator of the combustion device in proportion to the correction factor.

10. The method as claimed in claim 2, the method comprising:

correcting an operating characteristic curve on the basis of the estimated type of fuel, wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply, or a second operating characteristic curve between temperature-compensated difference and fuel supply;

determining a current fuel supply and/or a current fuel gas supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and controlling at least one fuel actuator of the combustion device as a function of the current fuel supply and/or the current fuel gas supply.

11. The method as claimed in claim 2, the method comprising:

assigning the estimated type of fuel to a calorific value;

correcting an operating characteristic curve on the basis of the assigned calorific value, wherein the operating characteristic curve is selected from: a first operating characteristic curve between temperature-compensated heat output and fuel supply, or a second operating characteristic curve between temperature-compensated difference and fuel supply;

determining a current fuel supply on the basis of the corrected operating characteristic curve and on the basis of a further variable selected from: the temperature-compensated heat output, or the temperature-compensated difference; and

controlling at least one fuel actuator of the combustion device as a function of the current fuel supply.

12. The method as claimed in claim 1, wherein the combustion device comprises a closed- and/or open-loop control unit with an operator control unit and wherein a plurality of mapping rules for selectable fuels and dependent on the first temperature are saved in the closed- and/or open-loop control unit, the method comprising, on setting the combustion device, selecting the saved mapping rules, dependent on the first temperature and/or on the fuel composition, from the plurality of mapping rules with the assistance of the operator control unit.

13. A combustion device comprising:

a combustion chamber;

a fuel supply channel for supply of a fuel to the combustion chamber;

a mass flow sensor in or on the fuel supply channel; and

a closed- and/or open-loop control unit in communicative connection with the mass flow sensor;

wherein the mass flow sensor comprises a heating element, a first resistor element, and a second resistor element different from the first resistor element, and/or a third resistor element different from the first resistor element and/or a fourth resistor element different from the first and second resistor elements opposingly relative to the second resistor element, wherein the closed- and/or open-loop control unit is configured to:

record a first temperature signal indicating a first temperature of the fuel using a first resistor element of the mass flow sensor;

process the first temperature signal to yield a first temperature;

determine a compensable value by recording a heat output signal indicating a heat output of a heating element of the mass flow sensor;

process the heat output signal to yield a heat output;

determine the compensable value as heat output; and

estimate a flow value for the fuel supply by compensation of the value compensable as a function of the first temperature and/or as a function of the fuel composition and/or as a function of the fuel gas composition on the basis of at least one saved mapping rule dependent on the first temperature and/or on the fuel composition and/or on the fuel gas composition and on the basis of a calibration characteristic curve saved for a reference gas.