EP4215815A1 - Device and use of a flow rate of a heating system and an ionisation signal of a heating system - Google Patents

Abstract

A method proposed here for operating a heater (2) of a heating system (1) comprising at least the following steps:
a) determining a first lower power limit of the heater (2) based on the flow rate of a heating circuit (3) of the heating system (1),
b) determining a second lower power limit of the heater (2) based on an ionization signal of the flame of the heater (2),
c) Operating the heater (2) in a power range above the larger value of the first or second power limit.

The invention is used to operate a heater (2) with an at least partially blocked exhaust gas path, in which the heater (2) is operated with operating parameters that enable safe operation despite a partially blocked exhaust gas path. The proposed method is also used to detect a blockage in the exhaust gas path, in which case safe operation of the heater is no longer possible.

Description

The invention relates to a method for operating a flame-forming heater of a heating system, in particular when a blocked exhaust system of the heater is detected, a computer program, a storage medium, a regulation and control unit, a heater and use of a flow rate and an ionization signal.

A blockage in the exhaust system of a heater can lead to unsafe operating states of the heater. Particularly in the case of heaters with a pneumatic gas/air combination, the composition of the mixture of combustion air and fuel gas can drift into a dangerous range if the exhaust system is at least partially blocked.

For this purpose, in the GB 210 5888 A proposed placing a sensor in an exhaust system and detecting a pressure that is compared to a reference value. Increased pressure can be an indication of a blocked exhaust system.

In the WO 2012/53681 A1 a system is proposed in which, in addition to a pressure in the exhaust system, a speed of a fan of the heater is detected. A change in the relationship between the two recorded values can indicate an at least partially blocked exhaust system.

A disadvantage of the solutions according to the prior art is the need for additional sensors, which, in addition to the cost and installation effort, also increases the complexity of the heating system.

The DE 10 2015 206 810 A1 proposes recognizing a blockage of at least one fluid path of the burner device on the basis of a control signal from a fan of a burner device and/or an ionization current of a flame. However, this method is inaccurate because an operational state of the burner device is not taken into account.

Proceeding from this, it is the object of the invention to propose a method for detecting a blocked exhaust system or for operating a heating device, which at least partially overcomes the problems of the prior art described. In particular, the method should enable reliable detection of a blocked exhaust system, but without increasing the complexity of the heating system. Furthermore, based on the detection of a (partially) blocked exhaust system, an (automatically) adapted mode of operation of the heater should also take place.

In addition, the invention should be easy to carry out and implement and to retrofit existing heating systems as easily as possible.

These objects are solved by the features of the independent patent claims. Further advantageous refinements of the solution proposed here are specified in the independent patent claims. It is pointed out that the features listed in the dependent patent claims can be combined with one another in any technologically meaningful manner and define further refinements of the invention. In addition, the features specified in the patent claims are the description more precisely and explained, with further preferred embodiments of the invention are presented.

1. a) Ermitteln einer ersten unteren Leistungsschranke des Heizgerätes basierend auf der Durchflussrate des Heizkreislaufes,
2. b) Ermitteln einer zweiten unteren Leistungsschranke des Heizgerätes basierend auf einem lonisationssignal der Flamme des Heizgerätes,
3. c) Betreiben des Heizgerätes in einem Leistungsbereich über dem größeren Wert von erster Leistungsschranke oder zweiter Leistungsschranke.

A method for operating a flame-forming heater of a heating system with a heating circuit contributes to this, comprising at least the following steps:

1. a) determining a first lower power limit of the heater based on the flow rate of the heating circuit,
2. b) determining a second lower power limit of the heater based on an ionization signal of the flame of the heater,
3. c) Operating the heater in a power range above the larger value of the first power limit or second power limit.

Steps a), b) and c) are generally carried out at least once in the specified sequence in a regular process sequence. In particular, it is possible to carry out steps a) to c) permanently or at regular (needs-based) time intervals.

The invention is used to operate a heater with an at least partially blocked exhaust gas path, the heater being operated with (predetermined) operating parameters that enable safe operation despite a partially blocked exhaust gas path. Likewise or incidentally, the proposed method includes the detection of an (undesirably large) blockage of the exhaust gas path, in the case of which safe operation of the heater is no longer possible.

A partially blocked exhaust gas path is characterized by an (undesirable) obstruction of the exhaust gas flow and thus an increase in the flow resistance of the exhaust gas path, for example due to its narrowing due to deposits on a wall of the exhaust gas path.

In principle, the method can be used with any heating device, but its use with a gas-powered heating device appears to be particularly sensible. The invention can be used particularly advantageously in a heater with a pneumatic gas/air combination.

The flame-forming heater can be set up in particular to burn one or more fossil fuels, such as natural gas or hydrogen, with the supply of combustion air, and thus provide thermal energy, for example for heating a building or for supplying hot water. The heater usually has at least one burner and a device that conveys a mixture of fuel (gas) and combustion air through a mixture channel of the heater to the burner. The exhaust gas produced by the combustion can be routed through an exhaust pipe of the heater, which can be part of a (superordinate) exhaust system, for example that of a building.

In particular, the heater can have a pneumatic gas-air combination, which is characterized in that a mass flow of combustion air is passed through a Venturi device (Venturi nozzle) and combustion gas can be added in accordance with the resulting negative pressure.

The heating circuit includes in particular a heating fluid that can be heated by means of the heater. The heating fluid can be fed to one or more consumers (eg heat exchangers such as radiators, etc. and/or hot water delivery devices such as showers, etc.) by means of a circulating pump. It is possible for the heating fluid to be heated again by the heater after heat has been emitted.

In step a), a first lower power limit of the heater is determined, based on the flow rate of a heating circuit of the heating system. This means in particular that a (current and/or maximum) flow rate of the heating fluid in the heating circuit is measured. The flow rate can then z. B. mathematically included in an assessment that leads to a value of a first lower power limit of the heater. The first lower power limit is in particular a measure of the minimum power requirement on the part of the heating circuit for the heater.

In step b), a second lower power limit of the heater is determined based on an ionization signal of the flame of the heater. This means in particular that a (current) quality of the flame of the heating fluid is determined by means of a measured ionization signal in the vicinity of the flame. This ionization signal can then z. B. mathematically included in an evaluation that leads to a value of a second lower power limit of the heater. The second lower power limit is in particular a measure of whether a controllable or stable flame formation is present in the heater.

In step c), the (controlled or adapted) operation of the heater takes place in a power range above the larger value of the first power limit or second power limit. Step c) can thus include comparing the first lower power limit determined according to step a) with the second lower power limit determined according to step b) and controlling and/or adjusting the operation of the heater in such a way that it is operated in a power range above the larger of the two power limits.

The first lower power limit according to step a) can be determined based on a current flow rate of the heating circuit. The flow rate of the heating circuit is essentially determined by the current operation and/or the maximum operation of the circulation pump of the heating circuit.

A first flow rate D _p can be specified with a value that is calculated and provided by the circulation pump through internal routines. The (current) value for the flow rate D _P provided by the circulating pump can be called up, for example, by a regulating and control device, which preferably also allows the method proposed here to be carried out. The circulating pump is in particular one whose performance is (automatically) regulated by means of a (current) differential pressure and/or a (current) temperature difference in the heating circuit. The difference in pressure between the heating fluid entering the circulating pump and the heating fluid exiting from it is referred to as differential pressure. The pressure in the heating circuit can drop when many consumers are active, which then results in an increase in the power of the circulation pump. In the other case, the circulating pump reacts in particular to temperature differences between a temperature in the (hot, downstream of the heater) flow and a temperature in the (colder, upstream of the heater) return. For example, if the temperature difference is small, this is an indication that the pump performance is currently too high, which leads to a reduction in the performance of the circulation pump. The power determined from such a pump control can be used to determine the current flow rate.

Furthermore, a (second) maximum flow rate D _max that can be achieved by the circulating pump, which corresponds to a maximum power consumption or a maximum operation, can be used. The maximum flow rate can be a heating circuit-specific and/or pump-specific parameter and can set itself in particular with a minimum flow resistance of the heating circuit. For circulating pumps that do not calculate the actual flow rate _DP by internal routines and/or by the circulating pump implausible values D _P provided, the maximum flow rate D _max can be used and the current flow rate can be determined using a (known) proportional relationship between the (existing) speed of the circulating pump and its flow rate.

Dabei sind:

DT

die Durchflussrate des Heizkreislaufes

TVor

die Vorlauftemperatur des Heizkreislaufes

TRück

die Rücklauftemperatur des Heizkreislaufes

cp

die Wärmekapazität des Wärmeträgers (beispielsweise Wasser)

P

die abgegebene Wärme des Heizgerätes

Q

die aufgenommene Leistung des Heizgerätes

η

der Wirkungsgrad des Heizgerätes (bekannte Funktion von TVor, TRück und Q

A (third) flow rate D _T of the circulating pump can be determined taking into account a flow and return temperature and the heat energy provided by the burner. The basis for the determination can be the following thermodynamic formula: $$\mathit{P}=n\times \mathit{Q}={\mathit{D}}_T\times {\mathit{c}}_p\times \left({\mathit{T}}_{\mathit{Before}}-{\mathit{T}}_{R\mathrm{u}\mathit{ck}}\right)$$

There are:

DT

the flow rate of the heating circuit

TVor

the flow temperature of the heating circuit

back

the return temperature of the heating circuit

cp

the heat capacity of the heat transfer medium (e.g. water)

P

the heat emitted by the heater

Q

the power consumed by the heater

n

the efficiency of the heater (known function of Tvor, Trück and Q

$$\mathit{mit}\Delta \mathit{t}=\frac{{\mathit{V}}_{\mathit{W}}}{{\mathit{D}}_T\left(\mathit{t}\right)}$$

Dabei sind:

• V_w die im Heizkreislauf enthaltene Menge Wärmeträger
• Δt der Zeitraum, in dem der Wärmeträger den Wärmetauscher durchströmt
• K die Wärmekapazität des Wärmetauschermaterials
• X(t) zeitabhängige Variablen
• X(t) Durchschnittswerte für den Zeitraum, in dem der Wärmeträger durch den Wärmetauscher strömt.

Taking into account the fluctuations and inertia of the system, the following equivalent formula can be used, especially when the flow and return temperatures and the absorbed power are not stabilized. $$\mathit{P}\left(\mathit{t}\right)=n\times \overline{\mathit{Q}\left(\mathit{t}\right)}={\mathit{D}}_T\left(\mathit{t}\right)\times {\mathit{c}}_p\times \left({\mathit{T}}_{\mathit{Before}}\left(\mathit{t}\right)-{\mathit{T}}_{R\mathrm{u}\mathit{ck}}\left(\mathit{t}-\Delta \mathit{t}\right)\right)-\mathit{K}\times \frac{\mathit{i.e}}{\mathit{German}}\times \left({\mathit{T}}_{\mathit{Before}}\left(\mathit{t}\right)+{\mathit{T}}_{R\mathrm{u}\mathit{ck}}\left(\mathit{t}\right)\right)$$

$$\mathit{with}\Delta \mathit{t}=\frac{{\mathit{V}}_{\mathit{W}}}{{\mathit{D}}_T\left(\mathit{t}\right)}$$

There are:

• V _w is the amount of heat transfer medium contained in the heating circuit
• Δ t is the period in which the heat transfer medium flows through the heat exchanger
• K is the heat capacity of the heat exchanger material
• X(t) time-dependent variables
• X ( t ) Average values for the period in which the heat carrier flows through the heat exchanger.

Thus, three flow rates D _P , D _max and D _T can be determined. These can also be set in relation to each other and thus result in a "superordinate" flow rate parameter that can be viewed here. In particular, in the case of an at least partially blocked exhaust system, the heat input into the heating fluid via the heater can no longer be maintained in an expected (constant) manner, which can be seen in such a ratio of the flow rates and leads to a partially blocked exhaust system being detected in this way or with it.

According to a preferred embodiment, the first lower power limit can be determined based on a minimum power of the heating device. The minimum power of the heater can be regarded as the lowest power of the heater with which it can be operated with a stable flame. For example, the first lower power limit can result from the minimum power of the heating device with a factor D _T /D _Use . In this case, D _Use can represent a calculation variable that is used to determine the first lower performance limit. In particular, the determination of the first lower power limit can include and be dependent on a verification (described below) of the parameter D _P determined by the circulation pump. The calculation variable D _Use can be defined as a function of the result of the verification of the parameter D _P determined by the circulating pump.

• 1.1 Wenn keine Verifikation der von der Umwälzpumpe bestimmten Durchflussrate D_p durchgeführt wurde, kann die Durchflussrate D_Use zur Bestimmung der (ersten) unteren Leistungsschranke als Minimum von D_max oder D_P (+ Toleranz) definiert werden.
• 1.2 Wenn eine Verifikation der von der Umwälzpumpe bestimmten Durchflussrate D_P durchgeführt wurde und diese Verifikation erfolgreich war, kann die Durchflussrate D_Use zur Bestimmung der (ersten) unteren Leistungsschranke als D_P (+ Toleranz) definiert werden.
• 1.3 Wenn eine Verifikation der von der Umwälzpumpe bestimmten Durchflussrate D_P durchgeführt wurde und diese Verifikation nicht erfolgreich war, kann die Durchflussrate D_Use zur Bestimmung der (ersten) unteren Leistungsschranke als D_max definiert werden.
• 2. Nachdem die Durchflussraten entsprechend bestimmt oder festgelegt wurden, kann die Durchflussrate D_T, ermittelt anhand der Vor- und Rücklauftemperatur des Heizkreislaufes, mit D_Use verglichen werden.
• 3. Wenn D_T>D_Use das Ergebnis des Vergleichs gemäß 2. ist, kann die (erste) untere Leistungsschranke aus der minimalen Leistung des Heizgerätes mit einem Faktor D_T/D_Use bestimmt werden.
• 4. Wenn das Ergebnis des Vergleichs gemäß 2. nicht D_T>_Use ist, kann die minimale Leistung des Heizgerätes als die (erste) untere Leistungsschranke definiert werden.

By way of example, a lower performance limit can be set using the flow rates D _P , D _max and D _T , including a verification of the values determined by the circulating pump Parameters D _P can be determined as follows:

• 1.1 If no verification of the flow rate D _p determined by the circulating pump has been carried out, the flow rate D _Use for determining the (first) lower performance limit can be defined as the minimum of D _max or D _P (+ tolerance).
• 1.2 If a verification of the flow rate D _P determined by the circulating pump has been carried out and this verification was successful, the flow rate D _Use for determining the (first) lower performance limit can be defined as D _P (+ tolerance).
• 1.3 If a verification of the flow rate D _P determined by the circulating pump has been carried out and this verification was not successful, the flow rate D _Use for determining the (first) lower performance limit can be defined as D _max .
• 2. After the flow rates have been determined or set appropriately, the flow rate _DT , determined from the flow and return temperature of the heating circuit, can be compared to D _Use .
• 3. If D _T >D _Use is the result of the comparison according to 2., the (first) lower power limit can be determined from the minimum power of the heater with a factor D _T /D _Use .
• 4. If the result of the comparison according to 2. is not D _T > _Use , the minimum power of the heater can be defined as the (first) lower power limit.

• eine Abschwächung des lonisationssignals, aufgrund einer Verkleinerung der Flamme, und/oder
• einem Rauschen des lonisationssignals, weil die Regelung mittels des lonisationssignals in einen instabilen Bereich kommt.

Die genannten Charakteristika des lonisationssignals der Flamme bei zumindest teilweise blockiertem Abgasweg können jedoch auch aus anderen Gründen auftreten, beispielsweise einer korrodierten lonisationselektrode oder auch einer instabilen Verbrennung. Für eine eindeutige Identifikation eines zumindest teilweise blockierten Abgaswegs kann gegebenenfalls z. B. eine gleichzeitige Überprüfung anderer Zusatzparameter und/oder des Durchsatzes im Heizkreislauf erfolgen.The determination of the second lower power limit of the heater according to step b) is based on the ionization signal of the flame. An at least partially blocked exhaust path of the exhaust system can be detected from the ionization signal of the flame of the heater in particular by:

• a weakening of the ionization signal, due to a reduction in the flame, and/or
• a noise of the ionization signal because the control by means of the ionization signal comes into an unstable range.

The stated characteristics of the ionization signal of the flame at least partially However, a blocked exhaust path can also occur for other reasons, such as a corroded ionization electrode or unstable combustion. For a clear identification of an at least partially blocked exhaust path z. B. a simultaneous review of other additional parameters and / or the throughput in the heating circuit.

According to an advantageous embodiment, a hybrid ionization signal can be determined that takes into account or assumes the two effects (attenuation and noise) of the ionization signal in the case of an at least partially blocked exhaust gas path. For this purpose, a weakening of the ionization signal can be detected and cumulated with a filtered noise component of the ionization signal. Advantageously, an at least partial blockage of the exhaust gas path can be reliably detected by the hybrid ionization signal and can be distinguished from a corroded electrode, for example. Since unstable combustion can regularly occur when the blockage of the exhaust gas path worsens, it can be advantageous to adapt the filtering of the noise component of the ionization signal in such a way that unstable combustion can still be identified.

mit $$\mathit{Rausche}{\mathit{n}}_{\mathit{neu}}=\frac{\mathit{Filter}\times \mathit{Rausche}{\mathit{n}}_{\mathit{alt}}+\mathit{Skalar}\times \left[\mathit{Ionsigna}{\mathit{l}}_{\mathit{neu}}-\mathit{Ionsigna}{\mathit{l}}_{\mathit{alt}}\right]}{\mathit{Filter}+1}$$

Die Parameter Filter und Skalar der dargestellten Gleichung dienen einer Verstärkung des lonisationssignales und einer Mittelung des Rauschanteils des lonisationssignals.A hybrid ionization signal can be determined, for example, as follows. The ionization signal is generally detected periodically, for example with a time interval of 100 ms [milliseconds]. The ionization signal can in particular be a raw data signal, that is to say a largely unchanged signal from the ionization electrode. In order to eliminate noise in the (raw data) ionization signal, a current signal (ion signal _new ) and at least one (old) signal (ion signal _old ) originating from a previous acquisition can be combined: $$\mathit{Ionsigna}{\mathit{l}}_{\mathit{Hybrid}}=\mathit{Ionsigna}{\mathit{l}}_{\mathit{new}}+\mathit{intoxication}{\mathit{n}}_{\mathit{new}}$$

with $$\mathit{intoxication}{\mathit{n}}_{\mathit{new}}=\frac{\mathit{filter}\times \mathit{intoxication}{\mathit{n}}_{\mathit{old}}+\mathit{scalar}\times \left[\mathit{Ionsigna}{\mathit{l}}_{\mathit{new}}-\mathit{Ionsigna}{\mathit{l}}_{\mathit{old}}\right]}{\mathit{filter}+1}$$

The parameters filter and scalar of the equation shown serve to amplify the ionization signal and to average the noise component of the ionization signal.

A second lower power limit can be determined on the basis of the ionization signal and/or the hybrid ionization signal.

A largely proportional change in the signal based on the rate or the extent of the blockage of the exhaust gas path is characteristic of a detection of a (partially) blocked exhaust gas path based on the flow rate of the heating circuit according to step a). In other words, a continuously changing signal based on the flow rate can be determined proportional to an exhaust gas path that continues to become clogged. In contrast, a sudden increase in the (hybrid) ionization signal can be detected as soon as a threshold value for blocking the exhaust gas path is reached.

Thus, there can now be a first lower power limit based on the consideration of the flow rate of the circulating pump and a second power limit based on the consideration of the ionization signal of the flame. Of these two lower power limits, the larger one can be selected as the lower power limit for operating the heater.

By operating the heater according to step c) with the higher of the two lower power limits, determined according to steps a) and b), it is ensured that the heater is not operated in a power range that can lead to unsafe operating states due to the blockage of the exhaust gas path.

According to an advantageous embodiment, according to a step d), the heater can provide or send information about an at least partially blocked exhaust path. In particular, the heater can provide or send information about an at least partially blocked exhaust path when one of the two determined lower power limits reaches a limit value. The limit value can be a preset value that can be stored, for example, in the memory of a regulation and control unit of the heater and represents a threshold value above which safe operation of the heater can no longer be guaranteed.

According to a further advantageous refinement, when step d) is carried out, the heater can switch off alternatively or cumulatively when a predefined limit value is reached with regard to one of the two lower power limits. Damage to the heater or accidents due to unsafe operating conditions can be prevented in an advantageous manner.

According to a preferred embodiment, the signals of the sensors necessary for carrying out a method proposed here can be verified at regular (time) intervals and/or as required. These are in particular a temperature sensor for a flow temperature, a temperature sensor for the return temperature and/or an ionization electrode.

For example, a verification of the temperature sensors in a return and flow of a heating circuit can be carried out by a three-way valve connecting the flow and return of the heating circuit via a heat exchanger to provide hot water, so that the signals of the temperature sensors, arranged for example before and/or after a (main) heat exchanger, can be compared. A determined temperature difference between the two temperature sensors can be used to calibrate their signals, since only the temperature difference is used for a method proposed here. A verification of the flow rate D _P calculated by internal routines of the circulating pump can be done by checking the signal of the internally determined flow rate D _P at different speeds (rotations) of the circulating pump. Such a verification can be carried out in particular when the heating device is in a standby mode or during a boiler run-on.

According to a further aspect, a computer program is also proposed which is set up to (at least partially) carry out a method presented here. In other words, this relates in particular to a computer program (product) comprising instructions which, when the program is executed by a computer, cause the latter to execute a method described here.

According to a further aspect, a machine-readable storage medium is also proposed, on which the computer program is stored. The machine-readable storage medium is usually a computer-readable data carrier.

According to a further aspect, a regulation and control unit for a heating device is also proposed, set up to carry out a method presented here. For this purpose, the regulating and control unit can have a processor, for example, or have it at its disposal. In this context, the processor can, for example, execute the method stored in a memory (of the regulation and control device).

According to a further aspect, a heater is also proposed, having a regulation and control device proposed here. The heater is, in particular, a gas heater with a burner and a delivery device that can deliver a mixture of fuel gas and combustion air to the burner. In particular, the heater can have a pneumatic gas/air combination.

According to a further aspect, the use of a flow rate of a heating circuit of a heating system and an ionization signal of a flame of a heater of the heating system to adapt the operating parameters of the heater when the exhaust system of the heater or an exhaust gas path is at least partially blocked is proposed.

The details, features and advantageous configurations discussed in connection with the method can accordingly also occur in the computer program presented here, the storage medium, the regulation and control device, the heating device and/or the use and vice versa. In this respect, full reference is made to the statements there for a more detailed characterization of the features.

A method for detecting a blocked exhaust system of a heating system, a computer program, a storage medium, a regulation and control device, a heater and a use are thus specified here, which at least partially solve the problems described with reference to the prior art. In particular, the method, the computer program, the storage medium, the regulation and control unit, the heater and the use at least contribute to enabling safe operation of a heater even when the exhaust path is at least partially blocked. In particular, a power range can be identified with a method proposed here, in which safe operation is possible despite the partial blockage of the exhaust gas path.

In addition, the invention can be implemented particularly easily. No additional sensor system of a heating device is necessary for carrying out a method proposed here. This means that it can also be carried out on existing heating devices without any problems. For this it is only necessary, for example, to store a computer program proposed here in a memory of the regulation and control device of the heater.

As a precaution, it should be noted that the numerals used here ("first", "second", ...) primarily serve (only) to distinguish between several similar objects, variables or processes, i.e. in particular they do not necessarily specify any dependency and/or sequence of these objects, variables or processes in relation to one another. Should a dependency and/or order be necessary, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described embodiment. If a component can occur several times ("at least one"), the description of one of these components can apply equally to all or part of the majority of these components, but this is not mandatory.

Fig. 1:

einen Ablauf eines hier vorgeschlagenen Verfahrens,

Fig. 2:

eine Heizungsanlage, aufweisend ein hier beschriebenes Heizgerät,

Fig. 3:

eine Darstellung von Parameterverläufen, die sich bei der Durchführung eines hier vorgestellten Verfahrens einstellen können,

Fig. 4:

eine Darstellung eines Rohdaten-Ionisationssignals und eines hybriden Ionisationssignals, und

Fig. 5:

eine Darstellung des hybriden lonisationssignals und der Leistung des Heizgerä-tes.

The invention and the technical environment are explained in more detail below with reference to the attached figures. It should be pointed out that the invention should not be restricted by the exemplary embodiments given. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be pointed out that the figures and in particular the proportions shown are only schematic. Show it:

Figure 1:

a sequence of a method proposed here,

Figure 2:

a heating system, having a heating device described here,

Figure 3:

a representation of parameter curves that can occur when carrying out a method presented here,

Figure 4:

a representation of a raw data ionization signal and a hybrid ionization signal, and

Figure 5:

a representation of the hybrid ionization signal and the power of the heater.

1 shows an exemplary and schematic sequence of a method proposed here. The method is used for the safe operation of a heater 2 with an at least partially blocked exhaust path or an at least partially blocked exhaust system of the heater 2. The sequence of steps a), b) and c) shown in blocks 110, 120 and 130 can occur during regular operation. In particular, however, steps a), b) and c) can be carried out continuously or at regular (needs-based) intervals.

In block 110, according to step a), a first lower power limit of the heater 2 is determined based on the flow rate of a heating circuit 3 of the heating system 1.

In block 120, according to step b), a second lower power limit of the heater 2 is determined based on an ionization signal of the flame of the heater 1.

In block 130, according to step c), the heater 1 is operated in a power range above the larger value of the first and second lower power limit.

2 shows an example and diagrammatically of a heating system 1, having a heater 2 proposed here. The heating system 1 has a heating circuit 3, comprising a flow 4, in which a circulation pump 18 can be arranged, and a return 5. When the circulation pump 18 is in operation, a heat transfer medium or heating fluid can flow through the heating circuit 3 in a flow direction 7. To measure a flow and return temperature of the heating circuit 3, a temperature sensor can be arranged in the flow 4 and in the return 5, which can be electrically connected to a regulation and control unit 8 of the heater 2.

The heater 2 may include an air intake duct 12 through which combustion air may flow. A Venturi device (Venturi nozzle) can be arranged in the air intake duct 12, in which a negative pressure can arise, which can control a mass flow of fuel gas to be supplied via a gas supply 13. A conveyor device 6 can be arranged in the adjoining mixture channel 14 and can feed the mixture of combustion air and fuel gas to a burner 9 . The burner 9 can be arranged in a combustion chamber 15 which can comprise a heat exchanger 16 which is connected to the heating circuit 3 in such a way that the heat carrier can flow through it. An ionization electrode 17 which can detect an ionization signal of a flame of the burner 9 can also be arranged on the burner 9 . The ionization electrode 17 can be electrically connected to the regulation and control device 8 .

The combustion products produced during the combustion of the mixture of combustion air and fuel gas by the burner 9 in the combustion chamber 15 can be fed to an exhaust gas path, designed here as an exhaust gas duct 10 , which leads out of the combustion chamber 15 and out of the heater 1 . The exhaust duct 10 is followed by an exhaust system 11, which can lead the combustion products to a chimney of a building, for example. Exhaust duct 10 and exhaust system 11 form the exhaust path.

A flow temperature sensor 36 can be arranged in the flow 4 and a return temperature sensor 37 can be arranged in the return 5 . A three-way valve 34 can be set up in a switching position to connect the flow 4 and return 5 via a heat exchanger 35 hot water preparation. The heat transfer medium in the heating circuit 3 can transfer heat to a volume flow of domestic or drinking water via the heat exchanger for hot water preparation 35 and thus provide hot water. This switching position of the three-way valve also allows a check of the temperature sensors supply 36 and return 37, since in particular without a volume flow to be heated service or Drinking water and an associated cooling of the heat transfer medium in the heat exchanger water heating 35 must have essentially the same temperature.

3 FIG. The abscissa of the diagram shown represents the output Q of the heater 2 and the ordinate axis the ratio of combustion air/combustion gas η. The influence of various blockages in the exhaust path (exhaust duct 10 or exhaust system 11) is shown by curves 33.

The curves of a lower power limit based on the flow rate of the circulating pump 21, a lower power limit based on the ionization signal of the flame 23 and a lower power limit based on the maximum flow rate of the circulating pump 22 are shown. Unclean combustion can occur in a critical area 19, accompanied by contamination of the exhaust gas duct 10 and exhaust system 11 and the environment.

4 1 shows a diagram with a raw data ionization signal 25 and a hybrid ionization signal 26 derived therefrom as a function of the time t. It is clearly evident that the hybrid ionization signal 26 manages to average out the noise of the raw data ionization signal 25 and to amplify it. In a critical area 19, unclean combustion can occur. A flame loss 27 can occur in particular in an area between the critical area 20 and the lower power limit based on the ionization signal of the flame 23 .

figure 5 shows a hybrid ionization signal 26 and a power of the heating device 2 over a time t by way of example and schematically. The heater 2 is operated with a lower power limit 30. For the hybrid ionization signal 26, a first limit 28 and a second limit 29 were defined. When the hybrid ionization signal 26 reaches the first limit 28, this indicates a destabilization of the flame 16, and when the hybrid ionization signal 26 exceeds the first limit 28, the power of the heater can be temporarily increased for the time it is exceeded. When the hybrid ionization signal 26 reaches the second limit 29, it can indicate that the flame 16 is in a critical state. In order to avoid a loss of flame in the long term, that is to say also during further operation, the lower power limit 30 can be permanently increased by an offset 32, for example.

Reference List

1

heating system

2

heater

3

heating circuit

4

leader

5

return

6

conveyor

7

Flow direction heating circuit

8th

regulation and control unit

9

burner

10

exhaust duct

11

exhaust system

12

air intake duct

13

gas supply

14

mixture channel

15

combustion chamber

16

heat exchanger

17

ionization electrode

18

circulation pump

19

critical area

20

flame loss

21

lower power limit based on circulation pump flow rate

22

lower power limit based on the maximum flow rate of the circulation pump

23

lower power limit based on the ionization signal of the flame

24

Workspace

25

Raw data ionization signal

26

hybrid ionization signal

27

flame loss

28

first border

29

second border

30

lower performance limit

31

performance of the heater

32

offset

33

Influence of various blockages in the flue gas path

34

Three-way valve

35

Heat exchanger water heating

36

Flow temperature sensor

37

Return temperature sensor

Claims (12)

Method for operating a flame-forming heater (2) of a heating system (1) with a heating circuit (3), comprising at least the following steps: a) determining a first lower power limit of the heater (2) based on the flow rate of the heating circuit (3), b) determining a second lower power limit of the heater (2) based on an ionization signal of the flame of the heater (2), c) Operating the heater (2) in a power range above the larger value of the first power limit or second power limit. Method according to claim 1, wherein in a step d) the heater (2) provides or sends an error message if at least one of the two lower power limits reaches a predetermined limit value. Method according to Claim 2, in which, in step d), the heating device (2) also switches off. Method according to one of the preceding claims, wherein in a step e) a verification of the signals of an ionization electrode (17) of the heating device (2) and/or at least one temperature sensor of a flow (4) or a return (5) of the heating circuit (3) is carried out. Method according to one of the preceding claims, wherein the flow rate of the heating circuit (3) by - A circulation pump (18) of the heating circuit (3) is provided, or - At least based on a temperature of the flow (4) and return (5) of the heating circuit (3), an inertia factor of a heat exchanger (16) of the heater (2) and a power of the heater (2) is determined. Method according to one of the preceding claims, wherein in step b) a hybrid ionization signal of the flame of the heating device (2) is used, the hybrid signal taking into account noise of the ionization signal and signal attenuation. Computer program set up to carry out a method according to one of the preceding claims. Machine-readable storage medium on which the computer program according to claim 7 is stored. Regulating and control device (8) for a heating device (2), set up to carry out a method according to one of Claims 1 to 6. Heating device (2) having a regulating and control device (8) according to Claim 9. Heating device (2) according to Claim 10, having a pneumatic mixture control. Use of a flow rate of a heating circuit (3) and an ionization signal of a flame-forming heater (2) to adjust the operating parameters of the heater (2) when the exhaust system (11) of the heater (2) is at least partially blocked.

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