EP1902254A1

EP1902254A1 - Method for regulating and controlling a firing apparatus and firing apparatus

Info

Publication number: EP1902254A1
Application number: EP05752994A
Authority: EP
Inventors: Martin Geiger; Ulrich Geiger; Rudolf Tungl
Original assignee: Ebm Papst Landshut GmbH
Current assignee: Ebm Papst Landshut GmbH
Priority date: 2004-06-23
Filing date: 2005-06-20
Publication date: 2008-03-26
Anticipated expiration: 2025-06-20
Also published as: EP1902254B1; DE102004055716B4; EP2594848B1; CA2571520A1; US20110033808A1; EP2594848A1; US20080318172A1; US8636501B2; KR20070043712A; KR20110129884A; WO2006000366A1; CA2571520C; DE102004055716A1; CA2773654A1; US8500441B2; DE102004055716C5

Abstract

Disclosed is a method for regulating a firing apparatus by taking into account the temperature and/or the burner load, especially in a gas burner. According to said method, the temperature (Tist) generated by the firing apparatus is regulated using a characteristic curve which represents a value range corresponding to a setpoint temperature (Tsoll) in accordance with a first parameter (mL, VL) that corresponds to the burner load (Q). A second parameter, preferably the excess air coefficient ( ), which is defined as the ratio between the actually delivered quantity of air and the quantity of air theoretically required for optimal stoichiometric combustion, is constant when representing the characteristic curve.

Description

Method for controlling and controlling a firing device and firing device

Description:

The invention relates to a method for controlling a firing device, in particular a gas burner, in which a value is determined, which depends on a measured temperature generated by the firing device, Furthermore, the invention relates to a firing device, in particular a gas burner, which comprises a device for measuring a value that depends on a temperature generated by the firing device comprises. Furthermore, the invention relates to a method for controlling a firing device, in particular a gas burner, and a firing device, in particular a gas burner, which comprises a gas valve for adjusting the fuel supply to the firing device.

In the household gas burners, for example, as a water heater, for the preparation of hot water in a boiler, to provide heating and the like. Ä. Used. In the respective operating states, different requirements are placed on the device. This concerns in particular the output of the burner. The power output is determined essentially by the adjustment of the supply of fuel gas and air and by the set mixing ratio between gas and air. The temperature generated by the flame is also a function of the mixing ratio between gas and air. The mixing ratio can be specified, for example, as the ratio of the mass flows or the volume flows of the air and the gas. However, other parameters, such as the fuel composition, have an influence on the sizes mentioned.

In addition, for any given air mass flow or gas mass flow, a mixing ratio can be determined in which the combustion efficiency is maximized, i. where the fuel burns as completely and clean as possible.

For this reason, it has proven to be useful to regulate the mass flows of gas and air and always set so that in each case an optimal combustion is achieved under changing requirements and boundary conditions. A regulation can take place continuously or at regular intervals. In particular, a regulation is required when the operating state is changed, but for example also because of changes in the fuel composition in continuous operation.

To provide the air / gas mixture through which the burner flame is fed, known gas burners are usually equipped with a radial fan, which sucks the mixture of air and gas during operation. The adjustment of the Massen¬ streams of air and gas can be done, for example, by changing the speed and thus the intake of the impeller of the radial fan. In addition, valves can be provided in the gas and / or air supply line, which can be actuated to adjust the individual mass flows or their ratio. To measure individual parameters, various sensors can be arranged at suitable locations. Thus, appropriate measuring devices can be provided for measuring the mass flow and / or the volume flow of the gas and / or the air and / or the mixture. Likewise, state variables, such as the temperature of the air, pressures, etc., can be measured at suitable locations, evaluated and used for the control.

The regulation of the mixing ratio is done today by default, especially for gas burners used in the household, by pneumatic control of a gas valve in dependence on the volume flow of the supplied air quantity (principle of pneumatic composite). In the pneumatic control, pressures or pressure differences at orifices, in constrictions or in Venturi nozzles are used as control variables for a pneumatic gas control valve, by means of which the gas supply to the air flow is set. However, a disadvantage of the pneumatic control is that mechanical components must be used which are subject to hysteresis effects due to the friction. Particularly at low operating pressures, inaccuracies in the control occur, so that the blower always has to generate a certain minimum pressure in order to achieve a sufficiently precise control, which conversely, however, leads to an oversizing of the blower for the maximum power. In addition, the expense of producing the pneumatic gas control valves equipped with diaphragms is considerable because of the high precision requirements. In addition, in the pneumatic network it is not possible to respond flexibly to changes in the gas type and quality. To be able to make desired adjustments to the gas supply nevertheless, additional equipment, such as actuators, must be prepared and adjusted, which means considerable additional expense in the installation or maintenance of a gas heater.

For these reasons, one goes to equip gas burner with an electronic Ver¬ bundle. With electronic control easily controllable valves, such as pulse width modulated coils or stepper motors, can be used. The electronic composite functions by detecting at least one signal characterizing the burn, which is fed back to a control circuit for readjustment.

However, when using the electronic interconnect, situations occur that can not be adequately addressed, such as a change in sensor sensitivity due to contamination. In addition, with changes in the load or the operating state or immediately after the start of operation of the gas burner there is a risk that the control will be delayed in time due to the inertia of the sensors, which leads to imperfect combustion and, in the extreme case, to extinction of the burner flame.

DE 100 45 270 C2 discloses a firing device and a method for controlling the firing device with fluctuating fuel quality. In particular, when the gas quality changes, the fuel-air ratio is changed accordingly. For each suitable type of fuel, the mixture composition readjusted until the desired flame core temperature is reached. In addition, characteristic maps are used for various fuels, from which a new, suitable fuel / air ratio is read out whenever the performance requirements change.

GB 2 270 748 A shows a control system for a gas burner. The regulation takes place here using a temperature measured at the burner surface. Since the surface temperature depends on the flow rate of the air-gas mixture, falls below a certain temperature, the speed of the fan rotor is lowered, whereby the air flow and thus the air-gas ratio is lowered.

From AT 411 189 B a method for controlling a gas burner is known, in which the CO concentration in the exhaust gases of the burner flame is detected by an exhaust gas sensor. A certain CO value corresponds to a certain gas-air ratio. Starting from a known, e.g. experimentally determined, gas-air ratio at a certain CO value, a desired gas-air ratio can be adjusted.

EP 770 824 B1 shows a regulation of the gas-air ratio in the fuel-air mixture by measuring an ionization current which depends on the excess air in the exhaust gases of the burner flame. With stoichiometric combustion, a maximum of the ionization current is known to be measured. Depending on this value, the mixture composition can be optimized.

A disadvantage of the last-mentioned methods, however, is that the feedback signal is detected only when the flame is burning and can be fed back to the control loop. In addition, the inertia of the sensors limits accurate readjustment. In addition, the sensors used are subject to contamination so that the combustion is suboptimally controlled over time and thus the pollutant values increase. In particular during the starting process, in which no combustion signal is present, or in the event of load changes in which significant changes to the loading conditions occur in a short time ¬ operating parameters are required, it can lead to difficulties and in extreme cases to extinguishing the flame. Frequently, for these reasons, additionally resorted to pneumatic regulator, which, however, an increase in the complexity of the system and the costs entails. Based on this, it is an object of the present invention to provide a simplified method for a fuel-independent control of a firing device be¬. A further object of the invention is to reliably ensure a gas-type-independent fuel supply, even in the event of rapid load changes and in the starting phase without any time delays.

These objects are achieved by a method according to claim 1 and a Feue¬ tion device according to claim 12 and by a method according to claim 24 and a firing device according to claim 31.

The method according to the invention for controlling a firing device, in particular a gas burner, comprises the steps of: determining a value which depends on a measured temperature generated by the firing device; Providing a first parameter that corresponds to a certain burner load; and regulating the value of the temperature generated by the furnace by means of a characteristic which represents a value range corresponding to a desired temperature as a function of the first parameter corresponding to a burner load, wherein a second parameter is shown in the representation of the characteristic curve , Preferably, the air ratio (D), defined as the ratio of the actual amount of air supplied to the amount of air theoretically required for optimal stoichiometric combustion, is constant.

The invention is based on the finding that a characteristic curve for regulating the value dependent on a temperature generated by the firing device does not depend on a type of gas used. The inventive method of control is thus gasartenunabhängig.

The temperature generated by the firing device is generally measured by a sensor arranged in the flame core or at the burner itself, for example at the burner surface. However, it can also be measured at the base of the flame, at the tip of the flame, or at some distance within the working range of the flame. The measured temperatures, depending on where the temperature sensor is mounted, and depending on the load and the air-fuel ratio, for example, values between 100 ⁰ C and 1000 ⁰ C.

The characteristic curve shown for a constant second parameter can be determined both empirically and by calculation. The second parameter value is the value predetermined, in which finds the optimal combustion with the existing burner statt¬. By way of example, as the second parameter value, the air ratio λ can be used, which should desirably lie at λ = 1.3. The air ratio λ is defined as the ratio of the actual amount of air supplied to the amount of air theoretically required for optimal stoichiometric combustion.

Among other things, the method is particularly simple and reliable in that the control can be carried out independently of the quality of the fuel and thus without analysis of the fuel. Thus, continuous or periodic corrections of the characteristic curve or a pre-selection from a characteristic field for different fuels / gases are dispensed with.

The first parameter corresponds in particular to one of the firing devices per unit of time to be supplied air quantity. This means the representation of a value corresponding to the nominal temperature at a constant second parameter value as a function of the amount of air supplied to the burner flame per unit of time. Conversely, a constant second parameter means that with the change in the amount of air, the amount of fuel supplied is changed accordingly to maintain the optimal stoichiometric ratio between air and fuel gas for combustion.

The first parameter preferably corresponds to a mass flow or volume flow of the air to be supplied to the firing device. The mass flow of the air can be determined, for example, by a mass flow sensor in the feed channel for the air supplied to the burner. When the load changes in accordance with a change in the air mass flow, the constant second parameter ^" changes likewise in the mass flow or volumetric flow of the fuel, which can likewise be measured by a mass flow sensor arranged at a suitable point.

The burner load is at a constant air ratio substantially proportional to the amount of air supplied to the firing device per unit time. For the characteristic curve used, it is therefore irrelevant whether the first parameter expresses an air or gas mass flow or a load, for example.

The method preferably comprises a comparison of the measured value dependent on the temperature with a desired value determined from the characteristic curve. As in In most control processes, a deviation of the actual temperature from the temperature setpoint value results in a setting of the operating parameters which reduces this deviation so long or until the deviation between the actual value and the setpoint value is compensated. For example, at a measured temperature below the setpoint temperature, the mixture can be enriched until the deviation of the actual value from the desired value no longer exists by gradually increasing the amount of fuel supplied. In the same way, the mixture can be emaciated accordingly at too high actual temperature.

The value corresponding to the setpoint temperature is preferably determined as a function of the first parameter from the characteristic curve. If, for example, the mass flow of the air is selected as the first parameter, then the mass flow of the air is predetermined and the setpoint temperature corresponding to this mass flow is read from the characteristic curve. The regulation takes place until the value of the actual temperature corresponds to the setpoint temperature value.

The measured value and / or the value range of the characteristic corresponds in particular to a temperature difference. For temperature measurement, it is possible, for example, to use thermoelements. In a particular embodiment, the temperature difference is a temperature difference between a temperature generated in the region of the burner flame and a reference temperature.

The reference temperature may correspond to the temperature of the air or of the mixture of air and combustion medium before it enters the region of the burner flame. If the temperature of the reference junction is known, the absolute temperature can also be determined. Alternatively, for example, the ambient temperature of the burner can serve as a reference.

The control may include an increase or decrease in the amount of gas supplied per unit time. In this embodiment, therefore, the temperature is controlled by enriching or leaning the mixture with fuel until the measured value, which is dependent on the actual temperature, coincides with the desired value.

The increase or decrease in the amount of gas supplied per unit time is carried out in particular by actuation of a valve. For example, a stepper motor can actuate an actuator of a valve, or modulate a pulse width or an electrical variable can be changed in an electrically controlled coil. The firing device according to the invention, in particular a gas burner, comprises: means for measuring a value which depends on a temperature generated by the firing device; Means for controlling the temperature generated by the firing device with specification of a first parameter corresponding to a certain burner load, and using a characteristic curve representing a value range corresponding to a desired temperature as a function of the first parameter corresponding to the burner load, wherein in the illustration the characteristic is constant, a second parameter which corresponds to a ratio of an amount of air to an amount of combustion medium in a mixture of air and combustion medium to be supplied to the firing device.

The device for measuring the temperature-dependent value can be arranged in particular in the flame kernel, at the burner surface, at the base of the flame or at the tip of the flame. The inertia of the temperature sensor depends essentially on the distance to the flame and on the inert masses of the sensor and its attachment.

The first parameter may correspond to one of the firing devices per unit of time to be supplied with the amount of air, in particular a mass flow or volume flow of the air.

The firing device preferably has a measuring device for measuring the amount of air and / or fuel medium fed to the firing device per unit time and / or of a mixture of air and fuel medium, in particular for measuring a mass flow or volume flow. The sensors are to be arranged in the device such that the most reliable possible conclusion can be drawn on the mass flows flowing through them. This can for example be the case in a bypass. The burner load at a constant air ratio is generally substantially proportional to the amount of air supplied to the gas burner per unit time.

The firing device may comprise means for comparing the value corresponding to the measured temperature with a desired value determined from the characteristic curve.

The means for measuring a value dependent on the generated temperature may be adapted to measure a value corresponding to a temperature difference. speaks. From this temperature difference, the absolute temperature can be determined at a known reference temperature.

In particular, the value corresponds to a temperature difference between a temperature generated in the region of the burner flame and a reference temperature, the reference temperature in particular corresponding to the temperature of the air or of the mixture of air and combustion medium before it enters the region of the burner flame.

The device for measuring a temperature value preferably comprises a part which is arranged at least partially in the region of the reaction zone of the burner flame.

For the measurement of the reference temperature, part of the device for measuring the temperature value outside the reaction zone of the flame, in particular in the region of an entry zone for the air supplied to the firing device and / or for the air / mixture mixture supplied to the firing device, can be used ¬ be orders.

The device for measuring a temperature value preferably comprises a thermoelement. In this case, a contact point of the different limbs of the thermocouple element is arranged in the region of the reaction zone of the burner flame, the reference point outside this reaction zone in order to detect a temperature difference between the flame and a region thermally decoupled therefrom, for example an environmental region of the gas burner ,

The value measured by the device for measuring a temperature value is preferably a thermoelectric voltage.

The means for regulating can be adapted to increase and / or reduce the amount of the combustion medium supplied to the combustion device per unit of time.

In particular, the firing device comprises a valve which can be actuated to increase or reduce the amount of gas supplied per unit of time.

In the case of the further method according to the invention for controlling a combustion device, in particular a gas burner, when the first parameter changes, which corresponds to the burner load, from a starting value to a target value the fuel supply to the firing device is adjusted by changing the opening of a gas valve from a first to a second opening value and by presetting a set value that depends on the first parameter, the second opening value being between an upper and lower limit value, and wherein the transition of the opening of the gas valve from the first to the second opening value, no control of the fuel supply performed and only after reaching the target value of the first parameter corresponding to the burner load, a control of operating parameters of the firing device is performed.

With the help of this method, stable conditions can be achieved with fast load changes, but especially during the starting process. A Nach¬ control of the gas valve, which takes a lot of time with strong fluctuations in the operating parameters and is imperfect due to the inertia of the sensors, can thus be omitted. In place of a control occurs a control that specifies a setpoint value for a new setting as a function of the target value of the first parameter. Only in the following step is readjusted using real measured variables. Regardless of the inertia of the sensors used for the control, the method can be used to find a fast and reliable adjustment of the gas valve. The real opening of the gas valve is between an upper and a lower limit. In the case of rapid setpoint changes, the control elements, for example the fan or a gas control valve, can be readjusted after a certain period of time, which depends on the inertia of the sensors. It thus takes place in the execution of the method according to the invention, a transition from a pure control to a control.

The parameter corresponding to the burner load may be the quantity of air to be supplied to the firing device per unit time, in particular a mass flow or volume flow of the air to be supplied to the firing device. The opening values of the gas valve can therefore be represented in this embodiment as a function of the mass or mass flow of the air. The characteristic of this characteristic is determined inter alia by the properties of the gas valve.

The burner load is essentially proportional to the amount of air supplied to the gas burner per unit of time. It is thus clear that the representation of the opening of the gas valve as a function of the mass flow of the air is equivalent to a depiction of the opening of the gas valve as a function of a load on the burner. The change of the opening of the gas valve may be performed by the modulation of a pulse width, by the variation of a voltage or a current of a valve spool, or by the operation of a stepping motor of a valve. Exceeding the upper or lower limit of the opening of the gas valve can be detected in the process. While after the control process the opening of the gas valve lies between the upper and lower limit value, after the control step, the gas opening may be above or below the upper or lower limit value. This can occur, in particular, if the setpoint values for the opening of the gas valve, which were never set when the characteristic was generated, deviate greatly from the optimally adjusted values. The reasons for this may be changes in the fuel composition, changes in the measurement characteristics of the sensors or the settings of the system parameters.

The characteristic curve which results from the setpoint values for the opening of the gas valve as a function of the parameter which corresponds to the burner load can be recalibrated on the basis of the operating parameters of the firing device set by the control. If, after regulation, the value of the opening of the gas valve falls outside the range bounded by the upper and lower limit values, a recalibration of the characteristic curve can be carried out. For example, during this recalibration, the setpoints may be shifted so that the new setpoint line passes through the adjusted value for the opening of the gas valve. In the same way, the upper and lower limit values can be shifted, so that the new setpoint curve is surrounded by a tolerance corridor, as in the previously valid characteristic curve.

Exceeding the upper or falling below the lower limit can, in particular after the expiry of a predetermined period of time, lead to switching off the firing device. This measure can be based on both safety concerns and economic considerations. Regulation in a range outside the desired range indicated by the limit values can, for example, indicate an undesired change in the predetermined settings of the gas burner, so that it may operate in an unsafe or ineffective operating range. The device would have to be checked and maintained below. A further firing device according to the invention, in particular a gas burner, comprises: a gas valve for adjusting the fuel supply to the firing device; a memory for storing set values that depend on a parameter corresponding to the burner load and upper and lower limits; a device for controlling the opening of the gas valve, which adjusts the opening of the gas valve from a first to a second opening value un¬ ter specification of a stored desired value in a change of the parameter corresponding to the burner load, from a starting value to a Ziel¬ the second opening value lies between a stored upper and a lower limit value, and wherein no control of the fuel supply is carried out during the transition of the opening of the gas valve from the first to the second opening value; and means for controlling which, after reaching the target value of the parameter which corresponds to the burner load, regulate operating parameters of the firing device. The control after the control step, for example, as in a method according to the. Proverbs 1 to 24 take place.

The gas valve may comprise an actuator, in particular a stepper motor, a pulse width modulated or an electrical size controlled coil.

The firing device preferably has at least one mass flow sensor and / or volume flow sensor for measuring the amount of air supplied to the firing device per unit time and / or the amount of fuel medium fed per unit time and / or the amount of mixture of air and fuel medium supplied.

In particular, the firing device can have a device in the region of the burner flame for measuring a temperature generated by the firing device.

The temperature sensor may be arranged, for example, in the region of the flame, but also on the burner in the vicinity of the flame. For example, a thermocouple can be used as a temperature sensor.

Further features and advantages of the subject of the invention will become apparent from the following description of specific embodiments. Show it:

1 shows a firing device according to the present invention; -Fig. FIG. 2 shows a characteristic curve which is used in carrying out the first method; FIG.

FIG. 3 shows a characteristic curve as used for carrying out the second method; FIG. and

A schematic representation of a structure of a control for performing a method.

FIG. 1 shows a gas burner in which a mixture of air L and gas G is mixed and burnt.

The gas burner has an air supply section 1, is sucked through the combustion air L. A mass flow sensor 2 measures the mass flow of the air L drawn in by a fan 9. The mass flow sensor 2 is arranged in such a way that a flow which is as laminar as possible is generated in its surroundings in order to avoid measurement errors. In particular, the mass flow sensor could be arranged in a bypass (not shown) and using a laminar element. ,

In the air supply section 1, a valve 3 may be arranged for the combustion air. However, as a rule, a regulated fan with air mass flow sensor will be used, so that the valve can be dispensed with.

For the gas supply, a gas supply section 4 is provided, which is connected to a gas supply line. The gas flows through the section 4, during operation of the gas burner. Through a valve 6, which may be an electronically controlled valve, the gas flows through a line 7 into the mixing region 8. In the mixing region 8, a mixing of the gas G with the air L takes place. The fan of the fan 9 is driven at an adjustable speed to suck in both the air L and the gas G.

The valve 6 is set so that, taking into account the other operating parameters, for example the speed of the fan, a predetermined air-gas ratio reaches the mixing area 8. The air-gas ratio should be chosen so that the most clean and effective combustion takes place.

Via a line 10, the air-gas mixture flows from the fan 9 to the burner part 11. There it exits and feeds the burner flame 13, which has a predetermined heat conductivity. to surrender. On the burner part 11, a temperature sensor 12, for example a thermocouple, is arranged. With the aid of this thermocouple, an actual temperature is measured which is used in the implementation of the methods described below for controlling or controlling the gas burner. In the present example, the temperature sensor 12 is arranged on a surface of the burner part 11. However, it is also conceivable to arrange the sensor elsewhere in the effective range of the flame 13. The reference temperature of the thermocouple is measured at a position outside the effective range of the flame 13, for example in the air supply line 1.

A device (not shown) for controlling or regulating the air and / or gas flow receives input data from the temperature sensor 12 and from the mass flow sensor 2 and outputs control signals to the valve 6 and to the drive of the blower 9. The opening of the valve 6 and the speed of the fan of the fan 9 are adjusted so that the desired air and gas supply results.

The control is carried out by performing the Ver¬ described below. In particular, the control device has a memory for storing characteristic curves or nominal values as well as a corresponding data processing unit which is set up to carry out the corresponding methods.

The first method according to the invention will be described with reference to FIG. FIG. 2 shows a characteristic curve in which the setpoint temperature T _{so as a} function of a mass flow mi. the combustion air, which is to be supplied to a gas burner, is applied. As can be seen from FIG. 2, a temperature is predetermined for the mass flow of the combustion air at a constant air ratio. For other values of the air ratio λ, another dependence of the setpoint temperature T _so n on the air mass flow m _{L would} result. The method is based on the observation that the target temperature T _so n belonging to a specific value of the mass flow of the combustion air for a given air number does not depend on the type of gas. The method thus works independently of gas types. The air ratio λ is chosen so that the most hygienic and efficient combustion is achieved. For example, a value λ = 1, 3 can be specified. In carrying out the method with the specified air ratio λ thus effective control is achieved regardless of the gas type and quality. To illustrate the method, a change starting from an operating state 1 to an operating state 2 is assumed. The change in the operating state requires a load change, for example a changed heat requirement. The operating state 1 corresponds to an air mass flow m _L i, the operating state 2 an air mass flow m _L2 . The burner load is at a constant air ratio λ substantially proportional to the mass flow of both the air and the fuel.

In carrying out the method, the new air mass flow is first mι. ₂ , starting from a desired in operating state 2 burner load Q _S0 || ₂ , adjusted. The air mass flow m _L can be measured on a mass flow sensor 2.

The corresponding opening of the gas valve is adjusted by means of the desired characteristic Gasventilöff¬ tion via mass flow

Instead of the mass flows and volume flows by means of a diaphragm with a pressure gauge or other parameters, such as the speed of the fan of the fan 9, could be detected.

After setting the air mass flow m _L2 and the gas valve 13 measured at Tem¬ perature sensor 12 in the area of the burner flame actual temperature Tj _St with the newly set air mass flow MI_ ₂ corresponding target temperature T _Sθ ιi compared ₂ according to the characteristic curve of FIG. 2

If there is a deviation between the actual value and the setpoint, readjustment takes place. The readjustment takes place by a leaning or enrichment of the air-gas mixture by actuation of the gas valve 6. The gas valve 6 is adjusted so long until the control process is completed, that is, until the target temperature T _S0 || ₂ corresponding actual temperature T _has set.

Instead of absolute actual and desired temperatures and temperature differences DT _is t, DT _S0 || as, for example, measured by a thermocouple, are used ^'. , Instead of the target temperature T n _as in accordance with a thermal voltage U n _as a function of the air mass flow m _L are applied. The reference temperature of the thermocouple 12 may, for example, in the air supply section 1, in a burner area outside the range of action of the burner flame 13 in the Umgege- Be measured by the burner.

The characteristic curve shown in FIG. 2 can be represented empirically or mathematically. For fast control, the use of a low thermal inertia sensor 12 located close to the flame 13 would be advantageous. Sheathed thermocouples with a jacket made of materials which are suitable for oxidation processes at high temperatures have proven to be particularly effective and stable. To increase the life of the temperature sensor 12 and to protect against Überla¬ Stung, it is advisable to install the sensor in an area which has a certain distance from the flame 13. The measured temperatures Tj _S t move, depending on the place of installation, burner load Q _so n and air ratio λ between 100 and 1000 ⁰ C.

In the case of gas heaters with low degrees of modulation, errors which occur due to fluctuations in the ambient temperature and the ambient pressure as well as the gas pressure and which lead to changing ratios between the air mass flow and the gas mass flow can be neglected in carrying out the method. In this case, the volumetric flow measurement, which is generally more cost-effective than the mass flow measurement of the combustion air, can generally be used.

A further method will be explained with reference to FIG.

FIG. 3 shows a dependency of the opening w of the gas valve 6, which determines the fuel feed, depending on the mass flow mi. the air supplied to the burner shown. The middle curve K3 corresponding to a target value curve, the predetermined opening values w n 6 _so a gas valve in response to a corresponding air mass flow m _L indicates.

When the prescribed burner load Q changes, for example when the operating state changes or when the system is started, the air mass flow m _{L is changed} from an initial value m _L1 to a second value m _L2 and adapted to the new load Q ₂ .

Since a regulation of the gas supply in the relatively short-term transition from m _L i to m _L2 would be greatly delayed due to the inertia of the sensors, the Rege¬ ment is turned off and the opening value w of the gas valve from the previously set Value W _{1 changed} to a new target opening value W ₂ . The value W ₂ lies on the sol ^{'löffnungskurve} K3.

The adjusting opening of the gas valve is in any case between an upper limit curve K1 and a lower limit curve K2, which indicate a tolerance range for the opening of the gas valve. The upper limit curve K1 corresponds to a maximum permissible opening of the gas valve, the lower limit curve K2 to a minimum permissible opening of the gas valve 6.

This is followed by a control process. In the control process, the operating parameters of the firing device, in particular the setting of the valve 6 and the speed of the fan of the fan 9 are adjusted so that the combustion process is optimized. The scheme can be done in any way. In the present example it is done by measuring a flame from the Brenner¬ 13 temperature T produced in their area of influence _is tursensor by a Tempera¬ 12. Control can be achieved, for example, acids, such as in the previously described procedural.

It is useful to use pulse width modulated valves, electronically controlled valves or valves with a stepper motor actuated actuator. The control signal for adjusting the opening of the gas valve can accordingly trigger, for example, the operation of a stepping motor, or change the pulse width, the voltage or the current of a coil. The air mass flows ιm _L and _G m Gasmassen¬ flows are measured by mass flow sensors 2 and 5. FIG.

If a valve opening w, which lies above the upper limit curve K1 or below the lower limit curve K2, is set in a phase of the method before or after execution of the control process, then corresponding consequences can be drawn. For example, leaving the tolerance range between K1 and K2 can lead to a calibration process. During the calibration, the conditions set according to the control could be stored in a memory of the control device and used for the next start. The setpoint curve K3, like the limit curves K1 and K2, can be shifted so that a uniform tolerance corridor for the opening of the gas valve 6 around the setpoint curve K3 also results in the new curve. Alternatively, exceeding the limit curves K1 or K2 upwards or downwards after a certain period of time or with repeated overshoots or undershoots can cause the device to be switched off. It may happen that certain settings of the gas burner are adjusted over time or certain boundary conditions have changed so that a safety risk occurs or the gas burner operates in a non-effective operating state. A deviation of the opening of the gas valve from the permitted corridor can be triggered for example by a deviation of the gas pressure from the permissible inlet pressure range or by a malfunction of the sensors. The shutdown can thus be interpreted as an indication that a review and maintenance of the device is required.

By means of the described method, it is possible to ensure that, until an effective control of the gas supply can start, a plausible opening W _{2 of} the gas valve is set by the control, be it during a load change of the gas burner or in the starting phase. In this way it can be prevented that, for example, the flame goes out during the load change.

By the method is ensured at the start of the burner, that in a wide range, adapted to the predetermined burner load, can be ignited. During load changes, a quick adjustment of the gas supply to the new load takes place before the fine adjustment is found by a subsequent control.

FIG. 4 shows schematically and by way of example a control device for carrying out one of the methods according to the invention.

The measured air mass flow mi. and gemes¬ in the area of the burner flame sene actual temperature T _is used to control device as input signals. As is apparent from the representation of the characteristic curve in diagram A, the air mass flow m _{L is} directly proportional to the load of the burner Q. According to the characteristic curve shown in diagram B, the speed n of the fan, which is proportional to the heat output, is calculated from the determined load. read out and adjusted accordingly.

(The upper right optional function only serves to simulate an existing firing automaton an input speed.) This part of the diagram should be deleted, since it only adds to the confusion.) On the other hand, when load changes from the input variable air mass flow m _L , as shown in the diagram C, the target temperature T _so n the burner flame is determined. For a certain air mass flow, a setpoint temperature is specified. In a node D, this target temperature T _so n is compared with the measured actual temperature Tj _St. If there is a temperature difference .DELTA.T, so employs a control process, which is continued until the actual temperature Tj _S t of the target temperature T corresponds _to n. An approximation of the actual temperature Tj _St to the target temperature T _so n is, as shown schematically by the diagram E, by actuating the stepping motor of a Gasven¬ tils, which determines the fuel supply m _G changed. This results in enriching or leaning of the fuel-air mixture, which leads to an increase or decrease in the temperature generated by the burner.

The diagram F shows the opening of the gas valve in the form of the step setting of the stepping motor of the gas valve as a function of the air mass flow m _L. The curves (1) and (2) indicate an upper or lower limit curve. For given mass air flow m _L , the opening of the gas valve must always be in the target corridor defined by curves (1) and (2) during and after the control operations. In the case of deviations upwards or downwards, a corresponding measure can be initiated. For example, the gas burner can be switched off in order to exclude safety risks or ineffective operation. It can also be just a warning or recalibration of certain characteristics are performed.

Claims

Claims:

1. A method for controlling a firing device taking into account the temperature and / or the burner load, in particular in a gas burner, comprising:

Control of the temperature (Tj _St ) generated by the firing device by using a characteristic curve which has a value range corresponding to a setpoint temperature (T _so n) as a function of a first parameter (mι_, V _L ) corresponding to the burner load (Q) ), wherein in the representation of the characteristic curve, a second parameter, preferably the air ratio (λ), defined as the ratio of the actually supplied air quantity to the amount of air theoretically required for optimal stoichiometric combustion, is constant.

2. The method according to claim 1, characterized in that the first parameter ei¬ ner the Feuerun ^' gseinrichtung per unit time to be supplied amount of air (m _L , V _L ) corresponds.

3. The method according to claim 2, characterized in that the first parameter ei¬ nem mass flow (m _L ) or volume flow (V _L ) of the firing device zu¬ supplying air corresponds.

4. The method according to any one of the preceding claims, characterized in that the burner load (Q) is substantially proportional to the device supplied to the Feuerungs¬ amount of air per unit time (m _L , V _L ).

5. The method according to any one of the preceding claims, characterized in that the method comprises a comparison of the measured value dependent on the temperature (Tj _St ) with a determined from the characteristic curve and the setpoint temperature (T _so n) corresponding setpoint.

6. The method according to any one of the preceding claims, characterized in that the target temperature (T _SO ιι) corresponding value as a function of the first parameter (m _L , V _L ) is determined from the characteristic.

7. The method according to any one of the preceding claims, characterized in that the measured value and / or the value range of the characteristic curve a Tempe¬ raturunterschied (.DELTA.Ti _s t, .DELTA.T _so ii) correspond.

8. The method according to claim 7, characterized in that the temperature difference (ΔTj _St ) is a temperature difference between a temperature generated in the region of the burner flame (Tj _St ) and a reference temperature (T _rΘf ).

9. The method according to claim 8, characterized in that the reference temperature (T _ref ) corresponds to the temperature of the air or the air / combustion medium mixture before entering the region of the burner flame.

10. The method according to any one of the preceding claims, characterized in that the control comprises an increase or decrease in the amount of combustion medium supplied per unit time (m _G , V ₆ ).

11. The method according to claim 10, characterized in that the increase or decrease in the amount of combustion medium supplied per unit time (m _G , VQ) is carried out by actuation of a valve.

12. Firing device, in particular gas burner, comprising:

a device (12) for measuring a value which depends on a temperature (T _ist ) generated by the firing device;

Means for controlling the temperature generated by the firing device (Ti ₃ O under specification of a first parameter corresponding to a certain burner load (Q _so ii) and using a characteristic curve, the one of a Solltempera¬ (T _SO H) corresponding range of values in dependence represents a first parameter (m _L , V _L ) corresponding to the burner equipment (Q), wherein in the illustration of the characteristic a second parameter, preferably the air ratio (λ), is defined as the ratio of the actually supplied air quantity to the theoretically required for optimal stoichiometric combustion air quantity, is constant.

13. A firing device according to claim 12, characterized in that the first parameter corresponds to one of the firing device per unit time to be supplied air quantity, in particular a mass flow (m _L ) or volume flow (VL) of the air.

14. Firing device according to one of claims 12 or 13, characterized gekennzeich¬ net, that the firing device comprises a measuring device (2, 5) for measuring the firing device per unit time supplied amount of air and / or fuel medium and / or a mixture from air and fuel medium, in particular for measuring a mass flow (m _L , m _G , m _M ) or volume flow (V _L , V _G , VM).

15. Firing device according to one of claims 12 to 14, characterized gekennzeich¬ net, that the firing device comprises means for comparing the measured by the temperature (T _ist ) dependent value with a determined from the characteristic and the target temperature (T _SO ιι) corresponding setpoint ,

16. Firing device according to one of claims 12 to 15, characterized gekennzeich¬ net that means for measuring a dependent of the generated temperature value is adapted to measure a value corresponding to a temperature difference (.DELTA.Ti _St ).

17. Firing device according to claim 16, characterized in that the value corresponds to a temperature difference between a temperature generated in the region of the burner flame (T _ist ) and a reference temperature (T _rβf ), wherein the reference temperature is in particular the temperature of the air or the air. / Combustion medium mixture before entering the area of the burner flame (13).

18. Firing device according to one of claims 12 to 17, characterized gekennzeich¬ net, that the means for measuring a temperature value (12) um¬ sums a part which is at least partially disposed in the region of the reaction zone of the burner flame (13).

19. Firing device according to one of claims 12 to 18, characterized gekennzeich¬ net, that for the measurement of the reference temperature (Tref) part of the means for measuring the temperature value (12) outside the reaction zone of the flame (13), in particular in the region of an input zone for the air supplied to the firing device zu¬ and / or the air er / combustion medium mixture is arranged.

20. Firing device according to one of claims 12 to 19, characterized gekennzeich¬ net, that the means for measuring a temperature value (12) is a Thermoele- includes ment.

21. Firing device according to one of claims 12 to 20, characterized gekennzeich¬ net, that the gemes¬ of the means for measuring a temperature value (12) value is a thermoelectric voltage.

22. Firing device according to one of claims 12 to 21, characterized gekennzeich¬ net, that the means are adapted for control, the amount of the Feuerungsein¬ direction per unit time supplied combustion medium (nri _G , V _G ) to increase and / or decrease.

23. A firing device according to one of claims 12 to 22, characterized marked, that the firing device comprises a valve (6) which can be actuated to increase or to reduce the amount of combustion medium supplied per unit time (mG, VG).

24. A method for controlling a firing device, in particular a Gasbren¬ ners, characterized in that

with a change of a parameter (ITIL, V _L ) corresponding to the burner load (Q), from a starting value (Qi) to a target value (Q ₂ ), the fuel supply to the firing device by a change in the opening of a gas valve (6) ei¬ nem a first (W ₁ ) to a second opening value (w ₂ ) under specification of a desired value, which depends on the parameter (m _L , VL) is adjusted, wherein the second opening value (w ₂ ) between an upper and a lower limit value and wherein during the transition of the opening of the gas valve from the first (wi) to the second - opening value (w ₂ ) no control of the fuel supply performed and Errei¬ chen the target value of the parameter (m _L , VL), the burner load (Q), a control of operating parameters of the firing device is performed.

25. The method according to claim 24, characterized in that the parameter corresponding to the burner load (Q), the firing device per unit time zu¬ leading air volume, in particular a mass flow (m _L ) or volume flow (V _L ) of the firing device to be supplied air , is.

26. The method according to claim 24 or 25, characterized in that the burner load (Q) is substantially proportional to the amount of air supplied to the gas burner per unit time (m _L , V _L ).

27. The method according to any one of the preceding claims 24 to 26, characterized gekenn¬ characterized in that the change of the opening of the gas valve by the modulation of a pulse width, by the variation of a voltage or current of a valve coil, or by operating a stepping motor of a valve is performed ,

28. The method according to any one of the preceding claims 24 to 27, characterized gekenn¬ characterized in that an exceeding of the upper or lower limit of the Öff¬ voltage is detected.

29. The method according to any one of the preceding claims 24 to 28, characterized gekenn¬ characterized in that a characteristic curve, which results from the desired values for the opening (w) of the gas valve in dependence on the parameter (mι_, VL), that of Brennerbela¬ Stung (Q), is recalibrated based on the set by the regulation Betriebspara¬ meter of the firing device.

30. The method according to any one of the preceding claims 24 to 29, characterized gekenn¬ characterized in that an exceeding of the upper or falls below the lower limit, in particular after the expiry of a predetermined period of time, leads to switching off the firing device.

31. Firing device, in particular gas burner, comprising:

a gas valve (6) for adjusting the fuel supply to the firing device;

a memory for storing set values depending on a parameter (mi_, VJ corresponding to the burner load (Q) and upper and lower limits;

a device for controlling the opening of the gas valve which, upon a change in the parameter (m _L , V _L ) corresponding to the burner load (Q), from a starting value to a target value, the opening of the gas valve from a first (W ₁ ) to a second opening value (w ₂ ) while presetting a stored nominal value, the second opening value (w ₂ ) being between a stored upper and a lower limit value, and during the transition of the opening of the gas valve from the first (W ₁ ) to the second opening value (w ₂ ) no control of the fuel supply is performed; and Control means which, after reaching the target value of the parameter corresponding to the burner load (Q), regulate operating parameters of the firing device.

32. A firing device according to claim 31, characterized in that the gas valve (6) comprises an actuator, in particular a stepper motor, a pulse width modulated or controlled by an electrical variable coil.

33. Firing device according to one of claims 31 or 32, characterized gekennzeich¬ net, that the firing device at least one mass flow sensor (2, 5) and / or flow sensor for measuring the firing device per unit time supplied amount of air (m _L , V _L ) and / or the quantity of fuel medium (ITI _G , V _G ) fed in per unit time and / or the amount of mixture (ΠΓIM, VM) supplied from air and fuel medium.

34. Firing device according to one of claims 31 to 33, characterized gekennzeich¬ net, that the firing device in the region of the burner flame (13) has a Einrich¬ device (12) for measuring a temperature generated by the firing device (Ti _st ).