ES2957808T3 - Performance detection and air factor control using sensors in the combustion chamber - Google Patents

Abstract

Recording of performance and control of the air ratio using sensors in the combustion chamber. Method for controlling a combustion device (1) comprising a combustion chamber (2), a first (19) and a second temperature sensor (20) in the combustion chamber (2), an air actuator (4) to generate an air supply (5).) and a fuel actuator (7 - 9) to generate a fuel supply (6), the method comprising the steps: adjust the fuel actuator (7 - 9) and/or the air actuator (4); recording a first signal from the first temperature sensor (19); Determine at least a first combustion power (23) as a function of the first signal using a first characteristic curve (24), which indicates a first course of a combustion power (23) for the first temperature sensor (19) on the signal from the first temperature sensor (19); recording a second signal from the second temperature sensor (20); Determine at least a second combustion power (23) as a function of the second signal by means of a second characteristic curve (25), which indicates a second combustion power curve (23) for the second temperature sensor (20). (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Performance detection and air factor control using sensors in the combustion chamber

Background

The present disclosure relates to controls and/or regulators used in combustion devices, for example, in gas burners, in relation to combustion sensors. Combustion sensors in combustion devices are, for example, ionization electrodes and/or optical sensors. More specifically, the present disclosure refers to the regulation and/or control of combustion devices in the presence of hydrogen gas.

In the operation of a combustion device, its combustion performance must be known and/or adjusted. For combustion of hydrocarbons or pure hydrogen or a mixture of both, the air supply and the fuel supply must be adjusted to each other. In this way, a correct air factor A is achieved.

Additionally, there are external influences that can affect the air factor and/or combustion performance. Such external influences are, for example, the inlet pressure of the fuel, in particular of the fuel gas, and the composition of the fuel. Other examples of external influences are ambient temperature, ambient pressure and changes in the supply air path as well as in the exhaust gas path of the combustion device.

In addition to the mentioned sensors, sensors of this type that monitor the flame in a safety-oriented manner can be included in the control of the combustion performance and/or the air factor of a combustion device.

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

Furthermore, thermocouples and/or resistance temperature sensors are conceivable as sensors for recording combustion signals. Thermocouples and/or resistance temperature sensors must be thermally coupled to the supply air and/or mixture and/or exhaust gases and/or combustion plasma in a combustion device. Thermocouples and/or resistance temperature sensors are also thermally coupled to the mechanical support. Due to these couplings, thermocouples and/or resistance temperature sensors are so far too slow to monitor a combustion process.

In particular, such thermocouples and sensors are quite slow to monitor a flame in a combustion device.

European patent application EP1154202A2 was filed on April 27, 2001 by SIEMENS BUILDING TECH AG. The application was published on November 14, 2001. Document EP1154202A2 deals with a control device for a burner. The document EP1154202A2 claims a priority of May 12, 2000. For the application EP1154202A2 there is the granted European patent EP1154202B1. In addition, there is a patent document EP1154202B2 after opposition proceedings.

Patent EP1154202B2 distinguishes between low and high calorific value fuel gases. Two characteristic curves are used to distinguish between the two fuel gases. Each of the two characteristic curves refers to a control signal for an actuator of the combustion device via a speed of the fan of the combustion device. To control the combustion device, the control signals corresponding to the characteristic curves are weighted.

Furthermore, document EP1154202B2 claims the use of additional sensors to control the combustion device. Said additional sensors influence the positions of the actuators of the combustion device based on the results of their sensors. As an example of measurement data obtained from such additional sensors, document EP1154202B2 mentions a change in boiler temperature.

Patent application DE102004030300A1 was filed on June 23, 2004 by EBM PAPST LANDSHUT GMBH. The application was published on January 12, 2006. Document DE102004030300A1 deals with a procedure for adjusting an operating parameter of a combustion device.

Document DE102004030300A1 discloses a mixing region into which an air supply and a gas supply flow. A duct exits the mixing zone. The duct ends in a burner part. Above the burner there is a flame. A temperature sensor is optionally arranged on a surface of the burner part. The temperature sensor can also be located at another point in the effective zone of the flame. The temperature sensor may be

- in the core of the flame

- at the base of the flame,

- at the tip of the flame,

- but also at a certain distance from the flame, for example, on the burner plate itself. By determining and detecting the actual temperatures measured in the effective zone of the burner flame as a function of the set mixing ratio, the maximum temperature value and the corresponding mixing ratio are determined.

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

Document DE102004055716A1 deals with a procedure for regulating and controlling a combustion device. Document DE102004055716A1 claims a priority of June 23, 2004.

Document DE102004055716A1 also discloses a mixing region into which an air supply and a gas supply flow. A duct exits the mixing zone. The duct ends in a burner part. A flame is arranged above the burner part. A temperature sensor can be arranged, for example, in the flame area, but also on the burner near the flame. For example, a thermocouple can be used as a temperature sensor.

Document DE102004055716A1 teaches the control of the Treal temperature generated by a combustion device at a target temperature Tobj. A characteristic curve is used that specifies the target temperature Tobj as a function of the air mass flow rate and/or the load of the combustion device. As an additional parameter, the air factor A remains constant.

International patent application W02006/000367A1 was filed on June 20, 2005 by EBM PAPST LANDSHUT. The application was published on January 5, 2006.

Document W02006/000367A1 deals with a procedure for adjusting an air factor in a combustion device. Document W02006/000367A1 claims a priority of June 23, 2004.

Document W02006/000367A1 also discloses a mixing region into which an air supply and a gas supply flow. A duct exits the mixing zone. The duct ends in a burner part. Above the burner there is a flame. A temperature sensor can be arranged, for example, in the flame area, but also on the burner near the flame. For example, a thermocouple can also be used as a temperature sensor. Optionally, the temperature sensor is arranged on a surface of the burner part. The temperature sensor can also be arranged at another point in the effective zone of the flame. The temperature sensor may be arranged

- in the core of the flame

- at the base of the flame,

- at the tip of the flame,

- but also at a certain distance from the flame, for example, on the burner plate itself. The procedure of document W02006/000367A1 is based on the fact that the actual temperature Treal detected by the temperature sensor depends on an air factor A. The actual temperature reaches a maximum Tmax at A = 1. A maximum Tmax is now determined for a predetermined air mass flow rate mL using the temperature sensor by iteratively adjusting a gas mass flow rate. Subsequently, an air factor preferably A = 1.3 is established and the mass flow rate of air mL is increased accordingly.

Another international patent application WO2015/113638A1 was filed on February 3, 2014 by ELECTROLUX APPLIANCES<a>B, SE. The application was published on August 6, 2015. Document WO2015/113638A1 teaches a gas burner application and a gas cooking device.

Document WO2015/113638A1 discloses a monitoring device by which a gas supply is disconnected in the absence of a flame. To do this, the monitoring device cooperates with a closing device comprising a valve. The monitoring device may include a thermocouple or other sensor. Therefore, the surveillance device is security-oriented.

Document DE10045272A1 discloses a combustion device comprising a control device for the controlled generation of a fuel/air mixture with an adjustable fuel/air ratio, wherein a temperature sensor for the flame length and a temperature sensor for flame temperature are connected to the control device.

Japanese patent application JP2017040451A was filed on August 21, 2015 by NORITZ CORP. The application was published on February 23, 2017. Document JP2017040451A deals with a combustion device.

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

Delays due to sensors are included in the 2020 technical specification for IST RTD platinum sensors. The response time of a sensor to track 63% of a temperature change due to delays varies between 2.5 and 40 seconds. Generally, the response time depends on the dimensions of the sensor in question.

For the control of a combustion device, a gas-air pneumatic interconnection and/or an electronic interconnection can be considered. Technically, a modulation range of one to seven is generally achievable by means of a gas-air pneumatic interface.

During the combustion of pure hydrogen, no practically usable signal is formed at an ionization electrode. Therefore, ionization electrodes are hardly suitable for recording signals during the combustion of pure hydrogen. Consequently, a controlled electronic connection on the basis of a flame signal has so far only been technically feasible for fuel gases containing hydrocarbons.

Furthermore, in the case of an electronic connection, the combustion performance and air supply depend solely on the fan speed. If the use of other sensors is too complex, a correction for environmental influences is hardly possible. Such environmental influences concern, for example, air temperature, air pressure and changes in the path of the supply air or exhaust gases of the combustion device.

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

An objective of the present disclosure is to provide a regulation and/or control system that allows the combustion of fuel gases containing hydrogen. In particular, an objective of the present disclosure is to provide regulation and/or control that achieves a sufficient degree of modulation. Said control is also applicable for combustible gases containing hydrocarbons and/or for a mixture of combustible gases containing hydrocarbons with hydrogen.

Summary

The regulation and/or control of a combustion device based on a single signal from a temperature sensor is delicate. Essentially, the temperature sensor signal depends on its position in the combustion chamber of a combustion device. It must be taken into account that the temperature signal is a function of the supply of the fuel and air mixture and, therefore, depends on the combustion power. Furthermore, the temperature signal also depends on the mixing ratio between fuel and air and therefore on the air factor. With a single temperature sensor it is difficult to clearly assign a measured temperature value to an exact combination of combustion power and air factor. Therefore, an additional signal is usually needed. This signal is usually the air supply as a representative of a mixture supply or combustion power. With the temperature measured at or near the flame, the air factor can then be controlled as a function of the measured value and the air supply according to a given characteristic curve. This procedure is described in document EP1902254B1, which indicates the measured temperature in the range of values depending on the air factor and the combustion power. Alternatively, the air factor can be used as an additional signal and the mixture supply, i.e. the combustion power, can be determined on the basis of the air factor and the measured temperature. The recording or determination of fuel supply, in particular gas supply, may also provide such an additional signal.

Sensors accurate enough to determine air supply, mixture supply, or fuel supply are expensive. A less expensive sensor does not detect variations in ambient conditions, such as air temperature, air pressure, or even variations in the supply air and/or exhaust gas path. Such a less expensive sensor is, for example, the fan speed sensor. Consequently, said sensor has the disadvantage that it only incompletely determines the air supply.

The present disclosure addresses those difficulties by placing more than one sensor in the combustion chamber of a combustion device. In particular, more than one temperature sensor may be provided in the combustion chamber of the combustion device. The signals from both sensors, in particular both temperature sensors, are read and each of them processed into values of a combustion power. The signals from both sensors, in particular both temperature sensors, can also each be processed into a value of an air factor A. Subsequently, regulation and/or control can be carried out on the basis of the combustion power. determined and/or the air factor A determined.

The processing of the individual measurement signals alone into a combustion power or air factor value or a combination of combustion power and air factor is often ambiguous.

In the case of an ambiguous correlation of individual signals at different combustion powers, possible combustion powers matching the individual signals are determined. Pairs are formed from the combustion powers determined from the signals of the first mentioned sensor and the combustion powers determined from the signals of the second mentioned sensor. The pair with the smallest difference in combustion power is selected. Based on this torque, a current combustion power of the combustion device is determined.

Furthermore, these ambiguities can be resolved by arranging another sensor, in particular another temperature sensor, in the combustion chamber. A signal is read from the additional sensor, in particular from the additional temperature sensor. The read signal is thirdly transformed into a value of a combustion power and is included in the determination of a current combustion power of the combustion device.

Another possibility to resolve ambiguities is to include a supply signal in the evaluation. For example, said supply signal may be the speed of a fan in an air supply channel. Likewise, said supply signal may be a signal from a flow sensor in the air supply channel or in the fuel supply channel. Furthermore, a delivery signal can be obtained from the position of an air damper and/or the position of a fuel actuator. The use of a supply signal has the advantage that the assignment of the supply signal to the combustion power is usually unambiguous.

The two characteristic curves for determining combustion power torques are fixed for a given air factor. If the two sensors are properly placed in the combustion chamber, there is exactly one pair of points of the two sensor values for which both combustion powers are equal for all possible values of the air factor.

With the presented method, the combustion power in the value range can be determined as a function of the respective measurement signal at a predetermined nominal value of the air factor. The determination is carried out for each sensor arranged in the combustion chamber. In this way, both the air factor and the combustion power can be regulated to predefined target values. The combustion powers as a function of the associated sensor signal can be deposited as a polynomial for both functions. In a preferred embodiment, the two functions can be deposited as a sequence of points between which linear interpolation is performed over the minimum distance between the two points. If more sensors are used, a function of the combustion power is deposited in the value range of three or more sensors. For example, an additional sensor may be a third sensor in the combustion chamber or a supply sensor.

Control is carried out, for example, by first adjusting the air actuator or alternatively the fuel actuator. The adjustment is carried out until the combustion powers determined from both temperature values are equal or close to each other. The combustion power is then calculated, for example, as the average of the two determined combustion powers. The air actuator and fuel actuator are then adjusted until the calculated combustion power is at its nominal value, for example via a regulation circuit. Any resulting deviation of the air factor from the nominal value is readjusted again by the air actuator or alternatively the fuel actuator. As a result of the readjustment, the combustion powers calculated from the two measurement signals become equal again.

Alternatively, the air factor and combustion power can be adjusted together via multi-loop control within a dead band of target values.

By correcting the air factor, changes due to external influences on the fuel can be corrected. A change in fuel composition primarily affects the air factor. The procedure disclosed here corrects a deviation in the air factor. Likewise, a change in fuel inlet pressure and/or fuel temperature and/or air pressure and/or air temperature can be corrected by controlling the air factor.

External influences on the combustion power can also be compensated, since the combustion power can be recalculated and set to a predefined nominal value. Changes in the supply air/exhaust gas path can also be corrected in this way with respect to the air factor as well as with respect to the combustion power.

Brief description of the drawings

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

FIG. 1 shows a combustion device with two sensors for monitoring the flame in the combustion chamber.

FIG. 2 shows the plot of the combustion power through the measurement signal of a sensor arranged in the combustion chamber, if the correlation is unambiguous.

FIG. 3 shows the plot of the combustion power through the signals of two sensors arranged in the combustion chamber when the correlation of a sensor is not univocal.

FIG. 4 shows the plot of the combustion power using the signals from two sensors arranged in the combustion chamber when the signal curves intersect.

FIG. 5 shows the plot of the combustion power using the signals from two sensors arranged in the combustion chamber and the divergent plot of both signals when the mixture has become lean.

FIG. 6 shows the plot of the combustion power using the signals from two sensors arranged alternately in the combustion chamber and the deviation of both signals when the mixture has become lean.

FIG. 7 shows the layout of the supply air using the supply air signal for two different supply air exhaust paths.

FIG. 8 shows the plot of two predefined control curves for the fuel gas valve and the calculated adjustment curve for the actual fuel parameters and/or gas parameters.

Detailed description

FIG. 1 shows a combustion device 1 such as, for example, a wall-mounted gas burner and/or a free-standing gas burner. A flame from a heat generator burns in the combustion chamber 2 of the combustion device 1 during operation. The heat generator exchanges the thermal energy of the hot exhaust gases with another fluid, such as water. 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 hot fuels and/or fuel gases can be used to heat a material, for example, in an industrial process. According to another embodiment, the heat generator is part of a plant with power-heat coupling, for example, an engine of said plant. According to another embodiment, the heat generator is a gas turbine. In addition, the heat generator can be used to heat water in a lithium and/or lithium carbonate extraction plant. The exhaust gases 10 are discharged from the combustion chamber 2, for example, through a chimney.

The supply of air 5 for the combustion process is carried out through a driven (motor) fan. Through the signal duct 14, a control and/or regulation device 13 specifies to the fan the air supply V<l>that it must transport. In this way, the fan speed of the fan speed sensor 12 becomes a measurement for the air supply 5.

According to one embodiment, the fan speed determined by the sensor 12 is returned to the control and/or regulation device 13 from the fan and/or drive 4 and/or air actuator 4. For example, the Control and/or regulation 13 determines the speed of the fan through the signal duct 15.

The control and/or regulation device 13 preferably comprises a microcontroller. Ideally, the control and/or regulation device 13 comprises a microprocessor. The control and/or regulation device 13 may be a regulation device. Preferably, the control device comprises a microcontroller. Ideally, the control device comprises a microprocessor. The control device may comprise a proportional and integral regulator. Furthermore, the control device may comprise a proportional and integral and derivative controller.

Furthermore, the control and/or regulation device 13 may comprise a field-programmable (logic) gate arrangement. Furthermore, the control and/or regulation device 13 may comprise an application-specific integrated circuit.

In one embodiment, the signal conduit 14 or 15 comprises an optical fiber. In a particular embodiment, the signal conduit 14 or 15 is implemented as an optical fiber. Optical fibers offer advantages in terms of galvanic isolation and explosion protection.

If the air supply 5 is adjusted through an air damper and/or a valve, the position of the damper and/or valve can be used as a measure of the air supply 5. Additionally, a derived measured value can be used of the signal from a pressure sensor 12 and/or a mass flow sensor 12 and/or a volumetric flow sensor 12.

According to one embodiment, the air supply V<l>is the current air flow rate. The air flow rate can be measured and/or indicated in cubic meters of air per hour. Therefore, the air supply V<l>can be measured and/or indicated in cubic meters of air per hour.

The fuel supply V<b>is adjusted and/or regulated by the control and/or regulation device 13 with the help of at least one fuel actuator 7 - 9 and/or at least one adjustable valve 7 - 9 (per engine ). In the embodiment of FIG. 1, fuel 6 is a combustible gas. A combustion device 1 can then be connected to different fuel gas sources, for example, to sources with a high methane content and/or to sources with a high propane content. Likewise, it is provided that the combustion device 1 is connected to a source of a gas or a gas mixture, wherein the gas or gas mixture comprises hydrogen. In a special embodiment it is provided that the gas or gas mixture comprises more than five percent, in particular more than five percent by mass, of hydrogen. In another special embodiment, it is provided that the gas or gas mixture comprises only or substantially only hydrogen gas. In another embodiment, it is provided that the fuel and/or the gas and/or the gas mixture variably comprises from zero to thirty percent of the amount of hydrogen gas substance. In FIG. 1, the control and/or regulation device 13 adjusts the amount of fuel gas by means of at least one adjustable fuel valve 7 - 9 (per engine). The control value, for example a pulse width modulated signal, of the gas valve 7 - 9 is a measure of the amount of fuel gas. It is also a value for the fuel supply V<b>.

If a gas gate is used as a fuel actuator 7 - 9, the position of a gate can be used as a measure of the amount of fuel gas. According to a special embodiment, a fuel actuator 7 - 9 and/or a fuel valve 7 - 9 are adjusted by a stepper motor. In this case, the step position of the stepper motor is a measurement for the amount of fuel gas. The fuel valve and/or the fuel gate may also be integrated into a unit with at least one or more safety shut-off valves 7, 8. A signal line 16 connects the fuel actuator 7 with the control device and /or regulation 13. Another signal conduit 17 connects the fuel actuator 8 with the control and/or regulation device 13. In turn, another signal conduit 18 connects the fuel actuator 9 with the control and/or regulation device regulation 13. In a special embodiment the signal conduits 16 - 18 each comprise an optical fiber. Optical fibers provide advantages with respect to galvanic isolation and explosion protection.

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

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

A signal conduit 21 connects the temperature sensor 19 with the control and/or regulation device 13. In a special embodiment, the signal conduit 21 comprises an optical fiber. Optical fibers offer advantages in terms of galvanic isolation and explosion protection.

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

A signal conduit 22 connects the temperature sensor 20 to the control and/or regulation device 13. In a special embodiment, the signal conduit 22 comprises an optical fiber. Optical fibers offer advantages in terms of galvanic isolation and explosion protection.

FIG 2 shows the signal curve 24 of the combustion power 23 by the sensor signal of the first sensor 19 for a solid fuel gas at a predetermined and constant mixture ratio. In FIG 2, the sensor 19 is arranged in such a way that the combustion power 23 can be clearly assigned to the sensor signal. Said characteristic curve 24 is obtained, for example, if a temperature sensor 19 is placed near the burner 3. The characteristic curve 24 differs from the characteristic curve mentioned in document EP1902254B1 in that the characteristic curve 24 along the ordinate has the combustion power 23 and not the temperature signal. Consequently, the combustion power 23 can be determined from the signal by means of the characteristic curve 24 shown in FIG 2. For this, the air factor A is set for each combustion power 23. In a preferred embodiment, the curve characteristic 24 is deposited in the control and/or regulation device 13. The correlation is also carried out there. Alternatively, the characteristic curve 24 can be stored in an electronic circuit in the first temperature sensor 19 or in any other unit. Evaluation also takes place there.

With the characteristic curve 24, the combustion power 23 can be determined directly, so that an air supply sensor 12 is not necessary. If the metering of the fuel gas is assigned directly to the air supply 5, the combustion power 23 and The air supply 5 are also allocated directly to each other. In this way, the air supply 5 can be adjusted through the aforementioned correlation between the combustion power 23 and the air supply 5 and through the control signal according to the duct 14. Alternatively, the air supply 5 can be adjusted in this way through a closed regulation circuit. In a preferred embodiment, the air supply signal is present, but the correlation between the air supply 5 and the signal is subject to external influences. These may be changes in, for example, air temperature and/or ambient pressure and/or supply air/exhaust gas path. Typically, a signal in which such changes are not compensated for is the fan speed signal 4 or the position feedback of an air damper. The correlation between the air supply 5 and the sensor signal in the duct 12 compared to the reference conditions can be recalibrated regularly during operation. The recalibration is carried out with the help of the sensor signal and the combustion power 23 determined by means of the characteristic curve 24, as well as with the help of the correlation between the combustion power 23 and the air supply 5. This operation It has the advantage that the air supply 5 and therefore the combustion power 23 can be changed quickly with the signal from the sensor in the duct 12. On the contrary, the correction by means of the characteristic curve 24 is much slower. . Similarly, the characteristic curve of a gas supply sensor, for example fuel supply, can be corrected based on the position of a gas gate. In this case, the air control signal in duct 14 and therefore the air supply 5 are directly assigned to the fuel metering.

The course of the characteristic curve 24 strongly depends on the position of the sensor in the combustion chamber 2. A position of the sensor near or directly in the burner 3 has the disadvantage that the dynamics of the sensor signal is affected by the capacity heat output from burner 3. This makes the control slower. This makes control slow. Furthermore, it is desired to use the first sensor 19 to monitor the flame at the same time. In order to monitor the flame, the sensor 19 must be located in a position in or near the flame area. For flame monitoring, the sensor 19 must also react sufficiently quickly, that is, have a sufficiently small time constant. FIG. 3 shows the course of a characteristic curve 24 of the combustion power 23 as a function of the signal from the sensor of the duct 21, when the sensor 19 is arranged in the combustion chamber 2 in the flame area or close to it.

As can be seen in FIG 3, the combustion power 23 can no longer be clearly assigned to the signal from the duct sensor 21 by means of the characteristic curve 24. Therefore, a second sensor 20 is installed in the combustion chamber. combustion 2, which maps the signal from the duct sensor 22 to the combustion power 23 by means of a characteristic curve 25 that deviates from the characteristic curve 24. To allow an unambiguous correlation of the two sensor values to the combustion power 23 as function of two variables by means of the two characteristic curves 24 and 25, the pair of points with the signals in the ducts 21 and 22, which is assigned to the respective value of the combustion power 23 by means of the characteristic curves 24 and 25 , can only occur once for all values of the combustion power 23 in the range of values of the possible combustion powers 23.

In the control and/or regulation device 13, the two characteristic curves 24 and 25 can, for example, be stored as a polynomial. The correlation is then carried out by means of a rule with which the different exhaust gas powers are calculated for the signals 21 and 22 currently recorded by the characteristic curves 24 and 25. In a preferred embodiment, the characteristic curves 24 are deposited as a sequence of pairs of values (21/23) and (22/23). The signals of conduits 21 and 22 can be placed between the corresponding pairs of stored values (21/23) and (22/23). Adjacent pairs of values (21/23) and (22/23) corresponding to the signals from ducts 21 and 22 are then determined. Linear interpolation is performed to determine the combustion power 23.

Next, the deviations of the combustion powers 23 for the signals of the ducts 21 and 22 are determined. For this, the total of the difference between all the combustion powers 23 calculated from the characteristic curve 24 and all the values calculated from the characteristic curve. Of the two combustion powers 23 with the smallest difference, for example, the average value or one of the two calculated values is taken as the assigned value. If exactly one combustion power 23 exists for the signals of the ducts 21, 22 in the characteristic curves 24, 25 for at least one of the two characteristic curves 24, 25, this is taken as the result.

FIG 4 shows that the two characteristic curves can also intersect. As long as the aforementioned condition for unambiguous correlation is met, the combustion power 23 and therefore the air supply 5 can also be determined with said characteristic curves.

If the condition for unambiguous correlation is not always fulfilled, the correlation can be made unambiguous with the help of another signal. This additional signal may come from an additional sensor in the combustion chamber 2, which clarifies this correlation for the respective signals with ambiguous correlation. With this other sensor in the combustion chamber 2, another characteristic curve is deposited with which the combustion power 23 can be determined unequivocally as described above.

As a third sensor, an air supply sensor 12 and/or a fuel supply sensor is especially preferred. If the fan speed or the position of an air damper is used as the air supply sensor 12, the signal fed back to the duct 15 can be used to clarify the unambiguous correlation despite its inaccuracies described above. Such clarification can be made in particular if fuel gas values with the same or similar pair of values are very far apart. Advantageously, the fuel gas values with the same, or similar, pair of values measured in the ducts 21, 22 are not within the error range of the mentioned external influences.

However, with the presented procedure and arrangement, the combustion power 23 and from it the air supply 5 can be determined not only from the signals in the ducts 21, 22 of the sensors 19, 20 in the combustion chamber. combustion 2. Likewise, the presented procedure and arrangement can be used not only to determine the fuel supply 6 for a fixedly predetermined mixture of a fuel gas. With the presented means, the fuel, in particular the fuel gas, can also be metered in the correct proportion to the air supply 5. The prerequisite for this is that the air supply 5 and the fuel supply 6 can be freely adjusted by means of the respective actuators 4, 9 for air and fuel. FIG. 5 shows the behavior of the signals to the ducts 21 and 22 through the combustion power 23. FIG. 5 refers to the case where the mixture becomes too lean in relation to the set air factor A, i.e. there is too little fuel gas compared to the nominal value. The characteristic curves 24 and 25 correspond to the signals from the sensors in the ducts 21 and 22 for different combustion powers 23 when the mixture is adjusted so that the nominal air factor A<nom> is reached. If the mixture becomes leaner, characteristic curve 26 for sensor 19 and characteristic curve 27 for sensor 20 are produced. Typically, leaning shifts characteristic curve 24 towards characteristic curve 25 by a different amount than characteristic curve 26. towards characteristic curve 27.

In principle, for the desired correction of the air factor A, instead of the characteristic curves 24 and 25, two characteristic surfaces can be deposited as a function of the combustion power 23 on the respective temperature values of the ducts 21 and 22 and respectively the air factor A. Then it is possible to unambiguously determine the combustion power 23 and the air factor A. The requirement for this is that for each point the combustion power 23 and the air factor A over all pairs of points As a result, the signal value pair of conduits 21,22 occurs only once on both surfaces. Once the point pair is determined, the current combustion power 23 and the current air factor A can be directly correlated to the point pair. The two actuators 4 and 9 can then be corrected for the nominal value.

The condition of unambiguous determination that has been mentioned for the correction cannot always be fulfilled for both surfaces. A third signal is therefore often necessary to unambiguously determine the combustion power 23 and the air factor A. This third signal may come from another sensor in the combustion chamber. Preferably, however, it is the air supply signal from duct 14 or 15. For example, the third signal may come from fan speed feedback from a fan speed sensor 12 on the fan or from the position of an air gate. Likewise, the third signal can come from the position of a fuel actuator, in particular from the position of a gas valve 9. A positioning of the sensors in the combustion chamber that meets the requirements for an unambiguous correlation of the signals with combustion power 23 and/or air factor A in the value range is much easier to achieve with the help of the additional value of the third sensor.

Consequently, the correction of the combustion power 23 and/or the air factor A takes place if the mixture is richer than the nominal air factor A<nom>. The corresponding characteristic curve for the richer mixture then lies on the other side of the respective characteristic curve 24 or 25.

The deposit of two surfaces in the control and/or regulation device 13 is expensive. Therefore, in a preferred approach, only two functions 24, 25 of the combustion power 23 are deposited based on both sensor signals 21, 22 of the sensors 19, 20. The characteristic curves 24, 25 can each be deposited as a polynomial based on various measurement signals. The characteristic curves 24, 25 can also be deposited as a sequence of points in the control and/or regulation device 13. Preferably, a linear interpolation is carried out between the points. Signals from other sensors can be added in the combustion chamber 2 and/or in the air supply 5 and/or in the fuel supply 6, such as, for example, a fan speed sensor 12.

In a first variant, the control is carried out by keeping the air supply 5 constant or almost constant by means of the air actuator 4. The fuel supply 6 is modified by the fuel actuator 9 until a difference in the determined values of the combustion powers 23 of both characteristic curves 24, 25 are within a defined threshold value.

In a second variant, the fuel supply 6 is kept constant or almost constant by means of the fuel actuator 9. The air supply 5 is modified by means of the fuel actuator 9. The air supply 5 is modified by means of the actuator of air 4 until a difference between the determined values of the combustion powers 23 of both characteristic curves 24, 25 lies within a defined threshold value.

The direction of adjustment is determined by the difference between the two determined combustion rates 23, for example, detecting that the difference decreases. If, for example, more measured values from sensors are added, the sum of the calculated difference values, squared, is compared to the specified threshold value. This procedure ensures that the actual air factor A<real>is within the nominal air factor A<nom>specified according to characteristic curves 24, 25. In the next step the combustion power P<real> is determined, by For example, by calculating the arithmetic mean of the two combustion powers 23 determined with the help of the characteristic curves 24 and 25. The air actuator 4 and at least one fuel actuator 7-9 are then adjusted together until the power is reached. default combustion temperature P<nom>. The air factor A may deviate a little due to the adjustment of the combustion power. In this case, the air factor A can be regulated again, as described, by setting at least one fuel actuator 7 - 9 or the air actuator 4 to the desired combustion power P<nom>.

In a third variant, the combustion power 23 and the air proportion A are regulated directly by adjusting both actuators 4, 7 - 9. As in the first and second variants, the reach of the respective threshold value for the difference in the powers Combustion valve 23 is deposited as a criterion in the multiple circuit control.

In the above variants, near-constant means that the first actuator adjusts more slowly than the second actuator. Consequently, the nominal values for the air factor A<nom>and the combustion power P<nom> can always be achieved. In the second variant, the at least one fuel actuator 7 - 9 adjusts more slowly than the air actuator 4. In the first variant, the air actuator 4 adjusts more slowly than the at least one fuel actuator 7 - 9. Preferably, a sequence is selected in which the predetermined and different speed of the actuators 4 and 7 - 9 is used. The at least one fuel actuator 7 - 9 with stepper motor drive is faster than the actuator air 4 with motor-adjustable fan wheel and corresponding moment of inertia. Therefore, variant one is often chosen.

The presented procedure guarantees that during a change in combustion power the air factor A is corrected first and only then the combustion power 23. In this way, even during the change in combustion power, the combustion device 1 always operates with the correct air factor A<nom>. For this reason, the characteristic curves 24, 25 also correspond to combustion power characteristic curves 23 for the respective sensors 19, 20 with a predetermined air factor A<nom>. The nominal air factor A<nom>has a layout defined by the characteristic curves 24, 25 by the combustion power 23 and is arbitrary over a wide range. For example, the nominal air factor A<nom>may have an ascending or descending curve with the combustion power 23. In a special embodiment, the plot of the nominal air factor A<nom>is constant for the combustion power 23 .

In FIG. 6, the characteristic curve 24 of the first sensor 19 is shown at the value of the nominal air factor A<nom>and at the value of the depleted air factor 26. Furthermore, the characteristic curve 25 of the second sensor 20 is shown at the value nominal air factor A<nom>and at the lean air factor value 27. In particular, with a third sensor signal, an unambiguous correlation of the sensor signals can be reliably achieved with such a plot in ducts 21 and 22 with the air factor A. Similarly, a one-to-one correlation with the combustion power 23 can be achieved. The third sensor signal can be, for example, a fan speed feedback signal 4 through conduit 15.

During an adjustment of the combustion power 23 due to a changed combustion power demand, the air actuator 4 can be moved along a predetermined characteristic curve of an air supply sensor 12. For example, the predetermined characteristic curve can be based on a fan speed feedback or it may be a characteristic curve of an air damper position feedback. In FIG 7, said characteristic curve 28 deposited in the control and/or regulation device 13 is shown by means of the fan speed feedback 15 from a fan speed sensor 12 as a reference characteristic curve. The characteristic curve 28 refers to a specific and/or well-defined environmental condition.

For a control signal along fan motor duct 14 or an air damper position, as well as for a feedback position signal along duct 15, a similar signal is applied for a reference condition. In this case, the signal has been previously linearized from the control signal or a position signal fed back to the air supply 5 by means of a characteristic curve deposited in the control and/or regulation device 13.

Once the current combustion power 23 has been determined after correction of the air factor A, the characteristic curve 28 can be adapted to the current ambient conditions. Such environmental conditions are, for example, air temperature and/or air pressure and/or change in supply air/exhaust gas path. For the currently measured fan speed or reference regulation, it is known that the air supply 5 is a direct function of the combustion power 23. A direct function means that the air supply 5 does not depend on any other argument of the function other than the combustion power 23. The supply that has been determined from the characteristic curve 28 is also known. In this way, the correction factor can be determined for the current air supply 5 as a ratio between both signals. Since the characteristic curves of the reference air supply signals or the fan speed feedback signal pass through the zero point through the air supply 5, the characteristic curve 28 can be corrected with respect to the characteristic curve 29. Each characteristic curve value is multiplied by the determined correction factor. With the help of this procedure, the combustion power 23 and the air supply 5 can be quickly adjusted using the corrected characteristic curve 29. Meanwhile, the correction of the air supply 5 can be carried out slowly by means of the characteristic curves 24, 25. In this way, both operations are decoupled from each other. The fluctuations of the measured values of the combustion power 23 can also be averaged by a mean value filter and in this way the combustion power 23 can be stably determined. The combustion power 23 can also be corrected in this way. The rate of change of the combustion power is not affected in this case.

The characteristic curve on which the fuel actuator 9 moves is shown in FIG 8. Two reference characteristic curves 30, 31, which were determined for different pressures and/or different compositions of fuel gas, are deposited in the device of control and/or regulation 13. The characteristic curves 30, 31 describe the gas dosing signal by the air supply 5, represented by the corrected signal value of the air supply 5 or the combustion power 23. The dosing signal gas represents fuel supply and/or gas supply. The two characteristic curves 30, 31 were determined under reference conditions, that is, for certain inlet pressures and/or fuel gas compositions. The characteristic curve 30 was determined with a fuel or fuel gas with a high calorific value and/or with a high inlet pressure. The characteristic curve 31 was determined with a fuel or fuel gas with a low calorific value and/or with a low inlet pressure. In operation, the current ratio between the fuel gas and air is determined by shifting the signals from the sensors 19, 20 in the combustion chamber 2, as described above. The signals are shifted to a single pair of values on both characteristic curves 24 and 25 by shifting the fuel actuator 9 to this target.

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

When at least one fuel parameter and/or one gas parameter changes, this is achieved on the basis of correcting the weighting ratio by adapting the sensor signals in the lines 21 and 22 to the characteristic curves 24, 25 as described above. The new characteristic curve can be calculated with the new weighting parameter. The procedure for calculating the corrected characteristic curve 32 for controlling the fuel actuator 9 in the case of different fuel parameters and/or gas parameters corresponds to the procedure described in document EP1154202B2. The described procedure can also be used to correct a change in fuel composition or gas inlet pressure, since these parameters have an effect on the air factor A. The air factor A is regulated by adaptation to the characteristic curves 24, 25 as described above.

Another advantage of the method is that the two sensors 19, 20 can be used to monitor the flame, for example to detect a flame break. To do this, the two signals 21, 22 generated by the sensors 19, 20 are used to detect the presence of a flame, in addition to controlling the air factor A and the combustion power 23.

Thus, at least one signal 21 or 22 can be evaluated to see if it falls below a threshold value. The threshold values can be selected differently for the signal from the sensor 21 than for the signal from the sensor 22. If the respective threshold value is below, the temperature is so low, for example, that a flame can no longer burn. A signal is generated with which the safety shut-off valves 8, 9 are closed via the pipes 16, 17 so that unburned flammable fuel cannot escape. In another variant, the difference is formed between the two signals 21 and 22, for which care must be taken that both signals do not have the same temperature value during operation. If the flame goes out, both temperatures quickly equalize. If the difference between the two signals falls below a predefined threshold value, this is detected as a flame loss. It is ensured that the safety shut-off valves 8, 9 are closed.

The above refers to individual embodiments of the disclosure.

A wide variety of modifications can be made without departing from the scope of protection of the following claims.

Reference signs

1: Combustion device

2: Combustion chamber

3: Burner

4: Fan

5: Air supply

6: Fuel supply

7: Safety shut-off valve

8: Safety shut-off valve

9: Fuel metering valve, in particular fuel gas metering valve 10: Exhaust gas channel

11: Air supply signal

12: Air supply sensor, e.g. fan speed sensor

13: Regulation and/or control device

14: Duct for fan control signal

15: Air supply feedback duct, e.g. fan speed feedback duct

16: Conduit for the control signal of a safety shut-off valve

17: Conduit for the control signal of a safety shut-off valve

18: Conduit for the control signal of a fuel metering valve

19: First sensor in the combustion chamber

20: First sensor in the combustion chamber

21: Pipe for the measurement signal of the first sensor in the combustion chamber and signal from this pipe 22: Pipe for the measurement signal from the second sensor in the combustion chamber and signal from this pipe 23: Combustion power

24: Characteristic curve of the combustion power by means of the measured signal of the first sensor in the combustion chamber

25: Characteristic curve of the combustion power by means of the measured signal of the second sensor in the combustion chamber

26: Characteristic curve of the combustion power by means of the measured signal of the first sensor in the combustion chamber in case of lean mixture

27: Characteristic curve of the combustion power by means of the signal measured from the second sensor in the combustion chamber with lean mixture.

28: Characteristic curve of the air sensor signal before changing the exhaust gas path for modulation

29: Characteristic curve of the air sensor signal after changing the exhaust gas path for modulation

30: Characteristic curve of fuel supply by fuel control for a high calorific value fuel, in particular a high calorific fuel gas, and/or a high inlet pressure.

31: Characteristic curve of fuel supply by fuel control for a low calorific value fuel, in particular a low calorific fuel gas, and/or a low inlet pressure.

32: Characteristic curve determined by the combustion device to adapt to the current fuel parameters and/or the fuel gas parameters for modulation.

Claims (15)

1. Method for controlling a combustion device (1), the combustion device (1) comprising a combustion chamber (2) and a first temperature sensor (19) in the combustion chamber (2) and a second sensor temperature (20) in the combustion chamber (2), where the first temperature sensor (19) is different from the second temperature sensor (20), at least one fuel actuator (7-9) to generate a supply of fuel (6) and an air actuator (4) to generate an air supply (5), and the procedure comprises the steps of: Adjust the at least one fuel actuator (7 - 9) and/or the air actuator (4); Record a first signal from the first temperature sensor (19) Determine at least a first combustion power (23) as a function of the first signal using a first characteristic curve (24) that indicates for the first temperature sensor (19) a first plot of a combustion power (23) of the device. combustion (1) by the first signal from the first temperature sensor (19) Record a second signal from the second temperature sensor (20) Determine at least a second combustion power (23) as a function of the second signal using a second characteristic curve (25) that indicates for the second temperature sensor (20) a second plot of the combustion power (23) of the device. combustion (1) by the second signal from the second temperature sensor (20); Determine a comparison value from the at least one first determined combustion power (23) and the at least one second determined combustion power (23); and Repeat the above steps until the determined comparison value is less than a predetermined threshold value. 2. The method according to claim 1, wherein the combustion device (1) further comprises an additional temperature sensor in the combustion chamber (2), wherein the additional temperature sensor is different from the first temperature sensor (19). ) and is different from the second temperature sensor (20), and the procedure comprises the steps of: Record an additional signal from the additional temperature sensor in the combustion chamber (2) in addition to recording the signals from the first and second temperature sensors (19, 20); Determine at least one additional combustion power (23) as a function of the additional signal using an additional characteristic curve indicating for the additional temperature sensor another plot of the combustion power (23) of the combustion device (1) by means of the additional signal from the additional temperature sensor; Determine the comparison value from the at least one first determined combustion power (23) and the at least one second determined combustion power (23) and the at least one additional determined combustion power (23); and Repeat the above steps until the determined comparison value is less than the predetermined threshold value. 3. The method according to one of claims 1 to 2, and the method comprises the steps of: Determine a difference between the at least one first combustion power and the at least one second combustion power (23); and Determine the comparison value as a total of the difference between the at least one first and the at least one second combustion power (23). 4. The method according to one of claims 1 to 3, and the method comprises the steps of: Form pairs from all the combustion powers (23) determined; Determine the differences of all the pairs formed between the respective combustion powers determined (23) Square all determined differences; and Determine the comparison value as the sum of all squared differences. 5. The method according to one of claims 1 to 4, and the combustion device (1) comprises at least one actuator selected from the at least one fuel actuator (7 - 9) and from the air actuator (4), and the procedure includes the steps of: Determine a first comparison value from the at least one first combustion power (23) and the at least one second combustion power (23) Generate a corrective actuator signal from the first comparison value Transmit the corrective actuator signal generated from the first comparison value to at least one actuator to approximate the determined combustion powers (23) after sending corrective actuator signal Record a third signal from the first temperature sensor (19); Record a fourth signal from the second temperature sensor (20) Determine at least a third combustion power (23) based on the third signal using the first characteristic curve (24) Determine at least a fourth combustion power (23) based on the fourth signal using the second characteristic curve (25); and Determine a second comparison value from the at least one third combustion power (23) and the at least one fourth combustion power (23), where the second comparison value is less than the first comparison value as result of the approximation of the determined combustion powers (23). 6. The method according to one of claims 1 to 5, and the method comprises the step of: Determine a current combustion power (23) of the combustion device (1) as the average value of the at least one first combustion power (23) and the at least one second combustion power (23). 7. The method according to one of claims 1 to 5, and the method comprises the step of: Determine a current combustion power (23) of the combustion device (1) as a first power value selectively chosen from or at least a first combustion power (23) or at least a second combustion power (23). 8. The method according to one of claims 6 to 7, wherein the combustion device (1) comprises at least one actuator selected from the at least one fuel actuator (7-9) and the air actuator (4), and The procedure includes the steps of: Calculate a difference between the current combustion power (23) of the combustion device (1) and a nominal power of the combustion device (1); Generate an actuator signal from the calculated difference; and Send the actuator signal to at least one actuator. 9. The method according to one of claims 7 to 8, wherein the combustion device (1) comprises an additional air supply sensor (12), wherein for the additional air supply sensor (12) is deposited a function that projects an air supply (5) on a combustion power (23) requested from the combustion device (1), and the procedure comprises the step of: Correct the stored function based on the real combustion power (23). 10. The method according to claim 9, wherein the deposited function comprises at least one deposited value, and the method comprises the steps of: Register a signal from the additional air supply sensor (12); Process the signal recorded from the additional air supply sensor (12) into a measured value of the air supply (5) Calculate a function value depending on the measured value of the air supply (5) based on the stored function Determine a multiplicative factor from the quotient between the current combustion power (23) and the calculated function value; and Correct the stored function by the multiplicative factor by applying the multiplicative factor to at least one stored value of the stored function. 11. The method according to one of claims 1 to 10, wherein for two fuels with different fuel parameters a characteristic curve (30, 31) of an actuator signal for the at least one fuel actuator (7 - 9) depending on a combustion power (23) requested from the combustion device (1), and the procedure includes the steps of: Generating an actuator signal for the at least one fuel actuator (7-9) from the determined comparison value; Calculate a weighting factor from the characteristic curves (30, 31) deposited for the two fuels and from the actuator signal for the at least one fuel actuator (7-9); and Determine a characteristic curve (32) to adjust the at least one fuel actuator (7-9) as a function of a combustion power (23) requested from the combustion device (1) from the weighting factor and the characteristic curves. (30, 31) deposited for the two fuels. 12. The method according to claim 11, wherein the method comprises the step of: Calculate the characteristic curve (32) to adjust the at least one fuel actuator (7 - 9) as a weighted arithmetic average value from the characteristic curves (30, 31) deposited for the two fuels, where the weighting of the value Arithmetic means is performed as a function of the actuator signal for the at least one fuel actuator (7-9). 13. Combustion device (1) comprising a combustion chamber (2) and a first temperature sensor (19) in the combustion chamber (2) and a second temperature sensor (20) in the combustion chamber (2). ), where the first temperature sensor (19) is different from the second temperature sensor (20), at least one supply conduit in fluid connection with the combustion chamber (2), at least one actuator selected from at least one fuel actuator (7 - 9) and an air actuator (4), where the at least one actuator acts on the at least one supply channel, and the combustion device (1) further comprises a regulation device and/or or control (13) in communicative connection with the first temperature sensor (19), with the second temperature sensor (20) and with at least one actuator, where the regulation and/or control device (13) is designed to executing a procedure according to one of claims 1 to 12. 14. Computer program product comprising instructions that cause the combustion device (1) of claim 13 to execute the steps of the method according to one of claims 1 to 12. 15. Computer readable medium on which the computer program product of claim 14 is deposited.