ES3010718T3 - Heater with emergency control system - Google Patents

Abstract

The invention relates to a method for operating a heating device (100) for heating a building, comprising the following steps: a) operating the heating device (100) with a primary combustion control, b) detecting an implausibility and/or a malfunction of the primary combustion control, c) operating the heating device (100) with a secondary combustion control that differs from the primary combustion control if an implausibility and/or a malfunction of the primary combustion control has been detected. (Automatic translation with Google Translate, no legal value)

Description

DESCRIPTION

Heater with emergency control system

The invention relates to a method for operating a heater for heating a building and a heater for heating a building.

There are known heaters for heating buildings that use fossil fuels to provide hot water (heating and/or water supply). A wide variety of environmental conditions or disturbances can cause the heater's combustion control strategy to reach the system's limits. In such cases, the heater's hot water supply may be interrupted.

The state-of-the-art of systems known on the market attempts to provide the customer with a minimum level of comfort for as long as possible by limiting the heater's operating range. Shutting down the device when the conceptual limits of the respective combustion control system are reached can only be limitedly prevented by restricting the operating area, so customer satisfaction is also only limited. In many cases, shutting down the device is unavoidable.

A generic procedure is known from document DE 196 01 517 A1. A procedure for controlling a circulating water heater is known from document EP 0327 785 A1.

The objective of the invention is therefore to expand the working area of a heater. Furthermore, the user in particular should be provided with a higher level of comfort.

This objective is achieved through the characteristics of the independent claims. Advantageous configurations result from the characteristics of the subordinate claims.

This is helped by a procedure for operating a heater to heat a building, which comprises the following steps:

a) operate the heater with primary combustion control,

b) detect implausibility and/or alteration of primary combustion control,

c) operate the heater with a secondary combustion control that differs from the primary combustion control if an implausibility and/or disturbance of the primary combustion control has been detected, whereby the secondary combustion control uses fewer sensors than the primary combustion control.

The method can be used, in particular, to adjust the flue gas/air ratio for a burner of a flue gas-fired heater. Advantageously, the method provides emergency operational control if the primary combustion control fails. In other words, this means that, in particular, secondary combustion control achieves advantageous regulation of redundant combustion. Secondary combustion control contributes especially to maintaining minimum heater functionality and thus ensuring comfort. In this context, secondary combustion control can also be described as a comfortable safety mode.

Operation with redundant (secondary) combustion control is intended specifically to maintain the device's operating range as long as possible until trouble-free operation can be guaranteed again by eliminating external interference (emergency operation control). To date, combining more than one combustion control in a single heater to heat a building has not been considered, as it was considered undesirable due to cost.

In the event of implausibility or malfunction of the primary combustion control (e.g., based on a CO sensor, a mass flow sensor, and/or an ionization electrode), hot water comfort can be achieved using another (redundant) secondary combustion control, preferably with the aid of an ignition and monitoring electrode, preferably combined. This can be achieved, in particular, by approaching the flame rise point, which is physically linked to a defined gas-air mixing ratio (defined lambda). In particular, by recognizing the signal change when the flame rises and knowing the existing lambda when the flame rises, it is possible to activate the fan and/or gas valve at a target lambda, which can ensure advantageously clean combustion. If this process is generally performed cyclically, particularly at sufficiently short time intervals, a safe control state can be achieved.

The heater is generally gas- and/or oil-fired. In other words, this applies in particular to a heater designed to burn one or more fossil fuels such as liquefied gas, natural gas, and/or oil, possibly with the ambient air supply of a building, to generate energy for heating water, for example in a living space within the building. The heater can be, for example, a so-called gas condensing boiler. The heater typically has at least one burner and a conveying device such as a fan, which conveys a mixture of fuel (gas) and combustion air (via a mixing duct of the heater) to the burner. The exhaust gases resulting from combustion can then be conducted through an (internal) exhaust pipe of the heater to an exhaust system (of a home). Several heaters are usually connected to this exhaust system.

In principle, the building can be a residential and/or commercial building. The heater can be used specifically to heat only a portion of the building, such as a single dwelling or a single room. Alternatively or cumulatively, the heater can also be used to heat a building's water system (heating and/or supply water) or a dwelling's water system.

Secondary combustion control is simpler than primary combustion control. According to the invention, this is achieved because secondary combustion control uses fewer sensors than primary combustion control. This means that secondary combustion control can operate with fewer input variables. This allows secondary combustion control to be more robust than primary combustion control. Furthermore, redundancy for combustion control can be created relatively inexpensively. The robustness of secondary combustion control may come at the expense of accuracy, but this can be accepted in order to maintain the device's operating range as much as possible. Secondary combustion control preferably uses (only) one sensor. Particularly preferably, this sensor can be a flame monitoring electrode, in particular an ionization electrode. Preferably, in addition to input data (measurement data) from a sensor, secondary combustion control can also use performance data from a conveying device (e.g., a fan) and/or a heater gas valve. In contrast, primary combustion control may rely on a large number of sensors (at least two sensors recording different input variables).

In an advantageous embodiment, it is proposed that the primary combustion control be carried out based on a signal (sensor or measurement) from at least one sensor of the heater. For example, a gas flow sensor (volumetric or mass flow sensor), an air flow sensor (volumetric or mass flow sensor), a mixture flow sensor (volumetric or mass flow sensor), an exhaust gas sensor (e.g., CO sensor, O<2> sensor), a temperature sensor (e.g., for measuring the flame and/or burner temperature), and/or a radiation sensor (e.g., an infrared sensor, in particular for measuring the flame and/or burner temperature) are used, each of which, as a rule, transmits a measurement signal to the control device. In addition, the primary combustion control can also use measurement signals from the flame monitoring electrode. Depending on one or more of these measurement signals, a controlled variable can be determined and regulated depending on a reference variable.

In another advantageous embodiment, it is proposed that an implausibility and/or malfunction of the primary combustion control is detected via at least one sensor of the heater and/or a flame monitoring electrode of the heater. For example, an implausibility can be inferred if two or more sensors provide contradictory measurement results. Alternatively or cumulatively, a malfunction can be concluded if one or more of the sensors provide measurement results indicating that a flame has been removed (the flame has gone out). Alternatively or cumulatively, it is also conceivable that an implausibility and/or malfunction of the primary combustion control is recognized from information about external disturbing influences, such as environmental influences, weather influences, etc. For this purpose, for example, sensor data can be evaluated or external data (e.g., from a weather database) can be used.

In another advantageous embodiment, it is proposed that the secondary combustion control be carried out based on a signal from a flame monitoring electrode of the heater. The flame monitoring electrode can, in particular, be an ignition and monitoring electrode, such as an ionization electrode. In this context, the secondary combustion control can be carried out, in particular, based on a voltage or current signal from a flame monitoring electrode system.

In another advantageous embodiment, it is proposed that, in addition to at least one (additional) heater sensor, the flame monitoring electrode is provided. The flame monitoring electrode is preferably provided in addition to one or more of the following sensors: gas flow sensor (volumetric or mass flow sensor), air flow sensor (volumetric or mass flow sensor), mixture flow sensor (volumetric or mass flow sensor), exhaust gas sensor (e.g., CO sensor, O<2> sensor), temperature sensor (e.g., for measuring the flame and/or burner temperature), and/or radiation sensor (e.g., infrared sensor, in particular for measuring the flame and/or burner temperature).

According to another advantageous configuration, it is proposed that the following intermediate stages be carried out in step c):

i) varying at least one operating parameter of the heater, such as an air ratio (A), to approach a flame lift point,

ii) monitor the approach to the flame rise point using the flame monitoring electrode,

iii) setting the at least one operating parameter of the heater to a value that is determined depending on the value that the operating parameter had immediately before or when the flame rise point was reached.

In other words, this can be described in particular such that the heater burner is monitored during step c) (to provide secondary combustion control) by means of a flame monitoring electrode (e.g. ionization electrode), the signal from the flame monitoring electrode being measured directly or indirectly and the flue gas/air mixture being leaned during operation of the burner (in step c)) and the signal from the flame monitoring electrode being measured continuously, the gradient of the signal from the flame monitoring electrode being built up, if a certain gradient is exceeded or if the gradient increases disproportionately, the leaning of the flue gas/air mixture is stopped and the flue gas/air mixture is enriched in a defined manner.

Air can be conveyed through a fan with a fan motor, and the gradient of the flame monitoring electrode signal can be determined by dividing the differential signal from the flame monitoring electrode by the differential speed of the fan motor. Alternatively, or cumulatively, the combustion gas can be passed through a gas valve with an actuator, and the gradient of the flame monitoring electrode signal can be determined by dividing the differential signal from the flame monitoring electrode by the differential position of the actuator. Alternatively, or cumulatively, the gradient of the flame monitoring electrode signal can be determined by dividing the differential signal from the ionization electrode by the differential time. A constant voltage source or a constant current source can also be connected in series with the burner flame and a resistor, and the voltage drop across the resistor can be measured as a flame monitoring electrode signal.

In another advantageous embodiment, it is proposed to cyclically repeat intermediate steps i) to iii) at defined time intervals. Advantageously, this allows the secondary combustion control to provide continuous combustion control or a redundancy to the primary combustion control, which can also be used over a longer period of time.

If the cause of the primary combustion control failure or malfunction has been eliminated (for example, due to the intervention of a technician or the elimination of external disturbances, such as a storm), in most cases a switch from secondary combustion control to primary combustion control can be made (reversibility). In cases where a new switch to primary combustion control is no longer possible (a defect in the primary control and/or a sensor in the primary control), the heater can continue to operate permanently with secondary combustion control. The occurrence of a malfunction in the secondary control usually results in the heater being shut down due to a fault.

Furthermore, according to a further aspect, a computer program for carrying out a method presented herein may be described. In other words, this applies in particular to a computer program (product) comprising instructions that, when executed by a computer, cause it to execute a method described herein. Furthermore, according to another aspect, a machine-readable storage medium on which the computer program proposed herein is stored may also be described. The machine-readable storage medium is typically a computer-readable data carrier.

According to another aspect, a heater for heating a building is proposed, comprising a burner, at least one sensor and a control device, which is provided and configured to carry out a primary combustion control in dependence on a signal from at least one sensor, the heater further having a flame monitoring electrode protruding into the flame region of the burner, which provides the control device with a signal to carry out a secondary combustion control that differs from the primary combustion control, the secondary combustion control relying on fewer sensors than the primary combustion control.

The heater is configured to perform a method presented here. In this context, the heater's control device can be specially configured to carry out the method. For this purpose, the control device can, for example, have or access a memory in which a program for executing the method is stored. The program can be implemented, for example, by a processor of the control device. The program can be, for example, the computer program described above. The memory can be formed, for example, by the machine-readable storage medium described above. It is also conceivable that the method described above could be carried out with the heater presented here.

In a further aspect, the use of an ionization electrode to maintain control of the emergency operation of a heater for heating a building is also described.

The details, features, and advantageous configurations discussed in connection with the method may also be reflected in the software, storage medium, heater, and/or use, and vice versa. In this regard, full reference is made to the statements contained therein for a more detailed description of the features.

The invention will now be explained in detail with the help of the figures.

They represent:

Figure 1: Schematically an example sequence of the procedure in the form of a flowchart,

Figure 2: Schematically an exemplary structure of the heater, and

Figure 3: A time course of an ionization signal, as can be obtained from the procedure presented here.

Figure 1 schematically shows an exemplary sequence of the method in flowchart form. The method is used to operate a heater 100 for heating a building (not shown here). The sequence of steps a), b), and c) shown with blocks 110, 120, and 130 is exemplary and can be carried out in a regular operating sequence, for example. However, it is also conceivable that steps a), b), and c) are carried out at least partially in parallel.

In block 110, according to step a), the heater 100 is operated with a primary combustion control. In block 120, according to step b), a detection of an implausibility and/or malfunction of the primary combustion control is performed. In block 130, according to step c), the heater 100 is operated with a secondary combustion control that differs from the primary combustion control if an implausibility and/or malfunction of the primary combustion control has been detected.

Figure 2 schematically shows an exemplary structure of the heater 100 for heating a building. The heater 100 comprises a burner 1, at least one sensor 20, 21, 22, 23, 24, 25 and a control device 7, which is provided and designed to carry out a primary combustion control in dependence on a signal from the at least one sensor 20, 21, 22, 23, 24, 25. Furthermore, the heater 100 comprises a flame monitoring electrode 3 protruding into the flame region 2 of the burner 1 and providing the control device 7 with a signal for carrying out a secondary combustion control that differs from the primary combustion control. The heater 100, in particular the control device 7, is configured to carry out a method described here (see Figure 1).

In particular, the primary combustion control is carried out depending on a signal from at least one sensor 20, 21, 22, 23, 24, 25 of the heater 100. By way of example, in Figure 2, a gas flow sensor 20 for measuring a gas flow 30, an air flow sensor 21 for measuring an air flow 31, a mixture flow sensor 22, an exhaust gas sensor 23 for measuring an exhaust gas flow 32, a temperature sensor 24 and a radiation sensor 25 are provided for this purpose, each of which transmits a measurement signal to the control device 7. In addition, the primary combustion control can also access measurement signals from the flame monitoring electrode 3. Depending on one or more of these measurement signals, a controlled variable can be determined and regulated depending on a reference variable.

For example, an implausibility and/or malfunction of the primary combustion control can be detected by at least one of the sensors 20, 21, 22, 23, 24, 25 of the heater 100 and/or the flame monitoring electrode 3 of the heater 100. For example, an implausibility can be concluded if two or more of the sensors 20, 21, 22, 23, 24, 25 deliver contradictory measurement results. Alternatively or cumulatively, a malfunction can be concluded if one or more of the sensors 20, 21, 22, 23, 24, 25 deliver measurement results indicating flame lift (the flame has gone out).

Furthermore, secondary combustion control can be carried out depending on a signal from the flame monitoring electrode 3 of the heater 100. An ionization electrode is used here, by way of example, as the flame monitoring electrode 3, the functionality of which is explained in more detail below. Figure 1 also shows that, in addition to at least one further sensor 20, 21, 22, 23, 24, 25 of the heater 100, the flame monitoring electrode 3 is provided.

In step c), several intermediate steps can be carried out, which are shown in block 130 by way of example with blocks 210, 220 and 230. In block 210, according to intermediate step i), at least one operating parameter of the heater 100 is varied to approach a flame lift point. In block 220, according to intermediate step ii), the approach to the flame lift point is monitored by means of the flame monitoring electrode 3. In block 230, according to intermediate step iii), the at least one operating parameter of the heater 100 is set to a value that is determined depending on the value that the operating parameter had immediately before or when the flame lift point was reached.

An example of how the secondary combustion control can be particularly preferably carried out with sensor data from (only) the flame monitoring electrode 3 (and performance data from a conveying device (e.g., blower 8) and/or a gas valve 10) is described below, with reference to Figures 2 and 3:

In Figure 2, the burner 1 has, for example, a fan 8 with a fan motor 9 at an air inlet 12. A gas line 13, in which a gas valve 10 with an actuator 11 is located, opens into the air inlet 12. The fan motor 9 and the actuator 11 are connected to the control device 7. In the burner 1 there is a flame 2, into which an ionization electrode 3 penetrates (as a flame monitoring electrode 3). The ionization electrode 3 is connected to a voltage source 4. This is connected to its second electrode with a resistor 5, which in turn is connected to the burner 1. In parallel to the resistor 5, a voltmeter 6 is connected, which is connected to the control device 7.

When the burner 1 is in operation, the fan 8 draws in combustion air through the air inlet 12. The speed n of the fan 8 is continuously adjustable. The amount of flue gas supplied, which flows through the gas line 13, can be continuously changed via the gas valve 10; the number of stages n<s> of the actuator 11 is recorded here. In the blower 8, the flue gas and air are mixed together and ignited at the outlet of the burner 1, forming a flame 2. Since the ions in the flame 2 are electrically conductive, a current can flow between the ionization electrode 3 and the burner 1. This results in the application of an electrical voltage U<flame>. The flow of ions through the flame 2 ensures that the electrical circuit (burner 1, ionization electrode 3, voltage source 4, resistor 5) is closed.

In this context, Figure 3 shows the evolution of the voltage U measured across resistor 5 over the air ratio A and the fan speed n. U<0> is the voltage of the voltage source 4. The following applies: U = U<0> - U<flame>. It can be seen in Figure 3 that the voltage U measured across resistor 5 is minimal during stoichiometric combustion (A = 1.0). As the excess air increases, the voltage U increases continuously. At an air ratio of approximately 1.6, the voltage U increases significantly more than before. At an excess air of approximately A = 1.7, the flame rises. Ionization signals can no longer be measured; a safety valve, not shown, blocks the combustion gas supply.

In the case of secondary combustion control, burner 1 initially operates with a previously unknown excess of air. When gas valve 10 is constantly open, the speed n of blower 8 increases. This increases the air ratio A. This represents an example of how, in the intermediate stage i), at least one operating parameter (here, for example, the air ratio A) of heater 100 can be varied to approach a flame lift point.

The voltage drop U across the resistor 5 is continuously measured over time t and transmitted to the control device 7. The gradient AU/An is calculated in the control device 7, where n is the speed of the fan 8. If the gradient AU/An increases excessively from a certain point, this is an indication that the flame will soon take off and thus break up. The air ratio A is then approximately 1.6. This represents an example of how, in the intermediate stage ii), a preferred monitoring of the approach to the flame lifting point can be carried out by means of the flame monitoring electrode 3.

From this point onwards (with A = 1.6), the fan speed n is now deliberately reduced so that an air ratio of A = 1.25 is reached. This represents an example of how, in the intermediate step iii), at least one operating parameter of the heater 100 can be set to a value determined depending on the value of the operating parameter immediately before or upon reaching the flame rise point.

As an alternative to determining the gradient using the ratio of the differential signal to the differential speed AU/An, a gradient from the differential voltage AU to the differential actuator setting position An<s> can also be used when, instead of increasing the fan speed, the flue gas quantity is reduced. As an additional variant, a gradient over time (AU/At) can also be formed with constant leaning.

The operating state in which flame lift is imminent can be determined by comparing the current gradient with at least one previous gradient. If the current gradient exceeds the comparison value(s) by a certain percentage, the expected state is present. For example, the lowest measured gradient can be used as the comparison value. Alternatively, an absolute value can be specified. This represents an example of how, in intermediate step ii), preferred monitoring of the approach to the flame lift point can be carried out using the flame monitoring electrode 3.

To eliminate the influence of signal noise (fluctuations in the measurement signal around a trend line), the time difference or velocity difference should not be chosen too small. Instead of the voltage drop U across resistor 5, the flame voltage U<flame> can also be measured directly. However, in this case, the ionization voltage is maximum with stoichiometric combustion, and the ionization voltage signal drops as the air ratio increases. Instead of a constant voltage U<o>, a constant current source with a constant current I<0> can also be connected to the series connection of resistor 5 with flame 2. A specific voltage is determined depending on the flame resistance.

Intermediate steps i) to iii) can be repeated cyclically at defined time intervals to allow continuous combustion control.

The described heater 100 also represents an example of the use of an ionization electrode 3 to maintain control of emergency operation of a heater 100 for heating a building.

Thanks to the described procedure and the heater described, the heater's working area can be increased. Furthermore, the user can be provided with a higher level of comfort, as the heater breaks down less frequently.

List of reference symbols

100 heater

1 burner

2 Flame Area

3 Flame monitoring electrode

4 Voltage source

5 Resistance

6 Voltmeter

7 Control device

8 Fan

9 Fan motor

10 Gas valve

11 Actuator

12 Air inlet

13 Gas pipe

20 Gas flow sensor

21 Air flow sensor

22 Mixture flow sensor

23 Exhaust gas sensor

24 Temperature sensor

25 Radiation sensor

30 Gas flow

31 Airflow

32 Exhaust gas flow

Claims (10)

1. Method for operating a heater (100) for heating a building, comprising the following steps: a) operating the heater (100) with primary combustion control, b) detect an implausibility and/or malfunction in the primary combustion control, c) operating the heater (100) with a secondary combustion control that differs from the primary combustion control, when an implausibility and/or malfunction of the primary combustion control is detected; characterized in that the secondary combustion control uses fewer sensors than the primary combustion control. 2. Method according to claim 1, wherein the primary combustion control is carried out based on a signal from at least one sensor (20, 21, 22, 23, 24, 25) of the heater (100). 3. Method according to any of the preceding claims, wherein an implausibility and/or a malfunction of the primary combustion control is detected by at least one sensor (20, 21, 22, 23, 24, 25) of the heater (100) and/or a flame monitoring electrode (3) of the heater (100). 4. Method according to any of the preceding claims, wherein the secondary combustion control is carried out based on a signal from a flame monitoring electrode (3) of the heater (100). 5. Method according to claim 4, wherein the flame monitoring electrode (3) is an ignition and monitoring electrode. 6. Method according to claim 4 or 5, wherein the flame monitoring electrode (3) is an ionization electrode. 7. Method according to any one of claims 4 to 6, wherein the flame monitoring electrode (3) is provided in addition to at least one sensor (20, 21, 22, 23, 24, 25) of the heater (100). 8. Method according to any of claims 4 to 7, wherein in step c) the following intermediate steps are performed: i) varying at least one operating parameter of the heater (100) to approach a flame lift point, ii) monitoring the approach of the flame rise point by means of the flame monitoring electrode (3), iii) adjusting the at least one operating parameter of the heating apparatus (100) to a value which is determined based on the value that the operating parameter had immediately before or upon reaching the flame rise point. 9. Method according to claim 9, wherein the intermediate steps i) to iii) are repeated cyclically at defined time intervals. 10. Heater (100) for carrying out a method according to any one of the preceding claims, comprising a burner (1), at least one sensor (20, 21, 22, 23, 24, 25) and a control apparatus (7) which is provided and designed to carry out a primary combustion control based on a signal from the at least one sensor (20, 21, 22, 23, 24, 25), the heater (100) further comprising a flame monitoring electrode (3) protruding into the flame region (2) of the burner (1), and which provides the control apparatus (7) with a signal for carrying out a secondary combustion control which differs from the primary combustion control; characterized in that the secondary combustion control uses fewer sensors than the primary combustion control.