Method of calibration and burner device

Abstract

The invention relates to a method for calibrating a flame monitoring device (10), in which a fuel is supplied to a burner device (12) to generate a flame (14), and in which an ambient air flow (16) is supplied to the burner device (12) to generate a fuel-oxygen mixture, wherein in at least one calibration step (36) a combustion maximum (20), particularly in the case of stoichiometric combustion, of the flame (14) is exceeded, and wherein at least one further calibration step (38, 40) is carried out at a regular time interval (22). It is proposed that in the at least one further calibration step (38, 40) at least one calibration parameter, which influences at least one combustion parameter of the flame (14), is automatically adjusted relative to the at least one calibration step (36).

Description

State of the art

[0001] A method for calibrating a flame monitoring device has already been proposed, in which a fuel is supplied to a burner device to generate a flame, and in which an ambient air stream is supplied to the burner device to generate a fuel-oxygen mixture, wherein in at least one calibration step a combustion maximum, in particular in the case of stoichiometric combustion, of the flame is exceeded, and wherein at least one further calibration step is carried out at a regular time interval. Disclosure of the invention

[0002] The invention relates to a method for calibrating a flame monitoring device, in which a fuel is supplied to a burner device to generate a flame, and in which an ambient air stream is supplied to the burner device to generate a fuel-oxygen mixture, wherein in at least one calibration step a combustion maximum, in particular in the case of stoichiometric combustion, of the flame is exceeded, and wherein at least one further calibration step is carried out at a regular time interval.

[0003] It is proposed that in at least one further calibration step, at least one calibration parameter which influences at least one combustion parameter of the flame is automatically adjusted relative to at least one calibration step.

[0004] The inventive design of the method for calibrating the flame monitoring device advantageously provides high efficiency, since fuel consumption for at least one calibration step is automatically kept as low as possible. Advantageously, it provides a high level of user comfort, since temperature fluctuations caused by the calibration can be minimized, particularly through the automatic adjustment of the calibration parameter. Advantageously, it also provides low emissions, since fuel consumption for at least one calibration step is automatically kept as low as possible.

[0005] Preferably, the flame monitoring device comprises at least one ionization sensor. Alternatively or additionally, the flame monitoring device could also comprise at least one lambda probe or a temperature sensor and / or a comparable direct and / or indirect measuring method for measuring combustion quality. Preferably, the burner device is designed as an instantaneous water heater or boiler or the like. In particular, the burner device heats water. Preferably, thermal energy is supplied to the water by the burner device, in particular by a burner of the burner device. Preferably, the thermal energy is generated by the flame. Preferably, the heat is provided by the flame. Preferably, the fuel is designed as a combustion fluid, in particular as a fuel gas.For example, the flame could be generated by the oxidation of fuel, in particular natural gas and / or hydrogen and / or methane. Preferably, the fuel is introduced into the burner of the burner device. Preferably, the fuel is injected into the burner under pressure, for example, by a pump. Preferably, the ambient air stream contains at least oxygen. Preferably, the ambient air stream is generated by drawing in ambient air with a blower. Preferably, the ambient air stream is introduced into the burner of the burner device. Preferably, the blower generates a pressure in the burner that is greater than the ambient pressure. Preferably, the fuel is mixed with the ambient air stream, particularly in the burner. Preferably, a fuel-oxygen mixture is generated. The fuel-oxygen mixture has a specific mixing ratio.The mixing ratio is defined as the ratio of fuel to oxygen. Preferably, the fuel is oxidized / combusted with at least the oxygen from the ambient air stream, for example, in the burner. A "rich fuel-oxygen mixture" is understood to mean, in particular, a mixing ratio that contains less oxygen than is required for complete combustion / oxidation of the fuel. An "ionization sensor" is understood to mean, in particular, at least one measuring sensor, for example, an ionization electrode, which is configured to measure an ionization current. In particular, an electrical voltage is applied to the flame, for example, between the housing and the ionization sensor, from which the ionization current is generated, especially when a flame is present. Preferably, the ionization current depends on at least a certain flame intensity.Preferably, the ionization current increases with the flame intensity. Preferably, the ionization current reaches its maximum at least substantially at the combustion maximum. Preferably, when the combustion maximum is exceeded, which occurs particularly with a rich fuel-oxygen mixture, the ionization current decreases as the flame intensity decreases. For example, a combustion maximum could be reached at least substantially at a stoichiometric mixture ratio. For example, the flame intensity is lower with a leaner and / or a richer fuel-oxygen mixture than at the combustion maximum with stoichiometric combustion. "Stoichiometric" here refers in particular to a fuel-oxygen mixture that contains exactly the same amount of oxygen as is theoretically required for the oxidation of the fuel contained in the fuel-oxygen mixture.The term "configured" should be understood to mean specifically programmed, designed, and / or equipped. The fact that an object is configured for a specific function should be understood to mean, in particular, that the object fulfills and / or executes this specific function in at least one application and / or operating state.

[0006] Preferably, in at least one calibration step, the supplied ambient airflow is reduced to generate a rich fuel-oxygen mixture. Preferably, the fuel-oxygen mixture is enriched until the combustion maximum of the flame is exceeded. In particular, the combustion maximum must be exceeded in the at least one calibration step to successfully identify it. Preferably, the rich fuel-oxygen mixture is combusted, particularly along an increasing mixture ratio, at least substantially above the combustion maximum in the at least one calibration step. For example, a measurement signal from the ionization sensor is maximal at the combustion maximum. For example, a maximum ion current is generated at the combustion maximum. For example, the combustion temperature is maximal at least substantially at the combustion maximum.For example, at the combustion maximum, the fuel is at least substantially completely oxidized. In particular, to enrich the fuel-oxygen mixture, the ambient airflow is reduced while the fuel supply is kept at least substantially constant. Specifically, controlling the constant fuel supply prevents, for example, a pressure drop resulting from the reduction in ambient airflow from automatically increasing the fuel supply. Preferably, the at least one calibration step has at least a defined calibration duration, which is preferably less than 1 s, more preferably less than 5 s, advantageously less than 10 s, and particularly less than 20 s. Preferably, the combustion maximum is generated by a pulse. For example, the calibration duration could be at least 0.1 s, more preferably at least 1 s, and particularly at least 5 s.A "combustion maximum" is understood to mean, in particular, the oxidation of a fuel-oxygen mixture at a mixing ratio that results in a maximum measurement signal from the ionization sensor and / or a maximum combustion temperature. "At least substantially" in this context means, in particular, that the deviation from a predetermined value is less than 25%, preferably less than 10%, and most preferably less than 5% of the predetermined value.

[0007] Preferably, the at least one further calibration step is performed sequentially after the at least one calibration step. Preferably, the at least one further calibration step differs from the at least one calibration step in that the at least one calibration parameter is adjusted in the at least one further calibration step. Preferably, the calibration, in particular the at least one calibration step and the at least one further calibration step, is repeated iteratively. Preferably, the at least one further calibration step is performed with a time delay after the at least one calibration step. In particular, a plurality of calibration steps are performed sequentially for the calibration. The at least one further calibration step relates to the at least one preceding calibration step.A "combustion parameter" is understood to be, in particular, a value that influences at least one combustion property of the flame, such as a mixture ratio and / or an ambient airflow. "Automatic" is understood to mean, in particular, self-regulating, for example, based on measured values ​​and free from operator intervention. A "calibration parameter" is understood to be, in particular, at least one target value that influences the calibration of the flame monitoring device, at least qualitatively or quantitatively, preferably at least partially setting it. For example, the at least one calibration parameter could be a time, a mixture ratio, a fan speed, a valve position, or the like.

[0008] Furthermore, it is proposed that the calibration parameter be configured at least as a pulse height, which is used to adjust the fuel-oxygen mixture ratio. Advantageously, this approach can be implemented with low complexity, as the mixture ratio, in particular, can be adjusted simply and precisely. Preferably, the pulse height is adjusted by reducing the fan speed. Preferably, the ambient airflow is reduced by reducing the fan speed. Preferably, the mixture ratio becomes richer as the fan speed is reduced. Alternatively, the pulse height could be adjusted by increasing the fuel supply. The fuel supply could be adjusted by setting the opening state of a gas valve. In particular, the mixture ratio becomes richer as the gas valve is opened further.Alternatively or additionally, the calibration parameter could be set by comparable parameters that influence the fuel-oxygen mixture ratio.

[0009] Furthermore, it is proposed that the pulse height for at least one further calibration step be reduced, in particular by a maximum of 5%, compared to the at least one calibration step, if the at least one calibration step was successfully performed. Advantageously, high efficiency and low costs can be provided, since, in particular, fuel consumption for the at least one calibration step is automatically kept to the lowest possible level. Advantageously, high user comfort can be provided, since, in particular, temperature fluctuations caused by the calibration can be minimized by the automatic adjustment of the calibration parameter. Advantageously, low emissions can be provided, since, in particular, fuel consumption for the at least one calibration step is automatically kept to the lowest possible level.The pulse height could be reduced by at most 1%, preferably by at most 3%, preferably by at most 5%, and for example by at most 7%. The pulse height could be reduced by at least 0.5%, preferably by at least 2%, and for example by at least 6%. Preferably, the pulse height in the at least one further calibration step is reduced compared to the pulse height in the preceding calibration step. Preferably, the at least one calibration step is classified as successful if a double top is detected. Preferably, the measurement signal, in particular the ionization current, exhibits at least two maxima in a successful calibration step.

[0010] Furthermore, it is proposed that the pulse height for the at least one further calibration step be increased, in particular by a maximum of 10%, compared to the at least one further calibration step, if the at least one further calibration step was performed unsuccessfully. Advantageously, a high level of operational reliability can be provided, since, in particular, the increase in pulse height after an unsuccessful calibration step ensures the successful completion of the subsequent calibration step. The pulse height could be increased, in particular, by a maximum of 15%, preferably by a maximum of 12%, preferably by a maximum of 10%, and, for example, by a maximum of 7%, if the at least one further calibration step was performed unsuccessfully. The pulse height could be increased, in particular, by a maximum of 5%, preferably by a maximum of 8%, and, for example, by a maximum of 10%, if the at least one further calibration step was performed unsuccessfully.Preferably, the pulse height in the at least one further calibration step after an unsuccessful calibration step is increased more than the pulse height is reduced in the at least one further calibration step if the at least one calibration step was successful. Preferably, the at least one calibration step is classified as unsuccessful if only one combustion maximum is detected. Preferably, the measurement signal, in particular the ionization current, exhibits a maximum in an unsuccessful calibration step.

[0011] It is further proposed that the time interval between the at least one subsequent calibration step and the at least one subsequent calibration step be reduced, in particular by at least 50%, preferably by at least 80%, if the at least one subsequent calibration step is aborted unsuccessfully. Advantageously, a high level of operational reliability can be provided, since, in particular, the time interval until the next successful calibration is shortened. Preferably, the time interval is defined as the duration between the at least one subsequent calibration step and the at least one subsequent calibration step. Preferably, the time interval of the subsequent calibration step to the at least one subsequent calibration step in the case of an unsuccessful calibration step is, in particular, at least 10%, preferably at least 25%, compared to the time interval in the case of a successful calibration step.

[0012] Furthermore, it is proposed that a starting value for the pulse height be specified, which is set, for example, upon power-up or when an operating point changes. Advantageously, high operational reliability can be ensured, since the starting value is predefined and does not need to be determined automatically, which is time-consuming. Advantageously, high calibration efficiency can be ensured, since the starting value does not need to be determined iteratively, which is time-consuming. Preferably, the starting value is a standard value that provides a good approximation of the calibration parameter for at least a large proportion of the operating points. It is conceivable that the starting value is always specified for at least one subsequent calibration step when the operating point changes.Alternatively, the starting value could be set only in the case of a sudden change in the operating point for at least one further calibration step. The term "at least a large part" is to be understood as, in particular, at least 55%, advantageously at least 65%, preferably at least 75%, most preferably at least 85%, and most advantageously at least 95%.

[0013] Additionally, it is proposed that the initial value for the pulse height be determined by relating the pulse height of the last successful calibration step to at least a standard value. Advantageously, high operational reliability can be ensured, since a precise initial value is specified and does not need to be determined automatically, which would be time-consuming. Preferably, the initial value for the pulse height is calculated in Eq. 1 below. In particular, the Pulsh ö he start as the starting value for the pulse rate. In particular, the Pulsh ö he last succesful calibration as the pulse height of the last successful calibration step. In particular, the Pulsh ö he default as the standard value for pulse rate. In particular, the Pulsh ö he as the standard value for the pulse height. Alternatively, it is also conceivable that the pulse height is defined as a pulse height from at least one previous calibration step. Preferably, the Pulsh ö he at least in normal operation as the Pulsh ö he default trained. P u l s h ö he start = P u l s h ö he last succesful calibration P u l s h ö he default ⋅ P u l s h ö he

[0014] It is conceivable that the burner has several stages. For example, the pulse component could be determined separately for each burner stage. It is also conceivable that the standard value for the pulse height is calculated as an average value, for example, as an arithmetic pulse height over an operating period.

[0015] In addition, a burner device, particularly for a hot water heater, is proposed, which includes at least one flame monitoring device for carrying out the described method. Advantageously, high efficiency and low costs can be provided, since, in particular, fuel consumption for the at least one calibration step is automatically kept at the lowest possible level. Advantageously, high user comfort can be provided, since, in particular, temperature fluctuations caused by the calibration can be minimized by the automatic adjustment of the calibration parameter. Advantageously, low emissions can be provided, since, in particular, fuel consumption for the at least one calibration step is automatically kept at the lowest possible level. Preferably, the burner device includes at least one control and / or regulation unit.The term "control and / or regulation unit" shall be understood to mean, in particular, a unit with at least one control electronics unit. The term "control electronics unit" shall be understood to mean, in particular, a unit with a processor unit, a memory unit, and an operating program stored in the memory unit.

[0016] The calibration method and the burner device according to the invention are not to be limited to the application and embodiment described above. In particular, the calibration method and the burner device according to the invention may, to achieve a functionality described herein, have a different number of individual elements, components, units, and process steps than those specified herein. Furthermore, values ​​within the specified limits of the value ranges stated in this disclosure are also to be considered disclosed and freely usable. drawing

[0017] Further advantages will become apparent from the following description of the drawing. The drawing illustrates an embodiment of the invention. The drawing, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0018] They show: Fig. 1 a burner device with a flame monitoring device, Fig. 2 a schematic flow diagram of a method for calibrating the flame monitoring device and Fig. 3 a schematic calibration diagram with a pulse height and a combustion maximum. Description of the exemplary embodiment

[0019] The Figur 1 Figure 1 shows a burner device 12. The burner device 12 is configured to heat water in an instantaneous water heater, boiler, or the like. The burner device 12 includes a flame monitoring device 10. The flame monitoring device 10 includes an ionization sensor 52. The ionization sensor 52 is configured to generate a measurement signal 56. The measurement signal 56 is designed as an ionization current. The burner device 12 includes a blower 26. The burner device 12 includes a burner 28. The blower 26 is configured to supply an ambient air flow 16 to the burner 28. The burner 28 and the blower 26 are fluidically connected to each other via an ambient air duct 24. The burner device 12 includes a fuel supply valve 30. The fuel supply valve 30 is configured to supply fuel to the burner 28.The fuel supply valve 30 is configured to adjust a fuel supply 34. The fuel is in the form of a fuel gas. The fuel is in the form of natural gas, methane, hydrogen, or the like. The burner 28 has a fuel-oxygen mixture. The fuel-oxygen mixture has a mixing ratio 54, see . Fig. 3 The mixture ratio 54 is defined as a ratio of fuel to oxygen. The burner 28 is configured to combust the fuel-oxygen mixture. The burner 28 is configured to generate a flame 14. The burner device 12 includes a control and / or regulating unit 32. The control and / or regulating unit 32 is configured to calibrate the flame monitoring device 10 using the method described. The burner device 12 includes a fuel tank 18. The fuel tank 18 is configured as a gas cylinder. However, the fuel tank 18 could also be configured as a public fuel network or the like.

[0020] The Figur 2 shows a schematic flowchart of a procedure for calibrating the flame monitoring device 10.

[0021] In a calibration step 36, a combustion maximum 20 of the flame 14 is exceeded, cf. Fig. 3 The combustion maximum 20 is reached during stoichiometric combustion. At the combustion maximum 20, the ionization current of the ionization sensor 52 reaches its maximum. The combustion maximum 20 of the flame 14 is exceeded by reducing the ambient airflow 16. By reducing the ambient airflow 16, the fuel-oxygen mixture ratio 54 is increased. The mixture ratio 54 is set to a richer mixture. Alternatively or additionally, the fuel supply 34 could also be increased to enrich the mixture ratio 54. The ambient airflow 16 is reduced until a predetermined pulse height 58 of the mixture ratio 54 is reached.

[0022] In a further calibration step 38, a calibration parameter is automatically adjusted compared to the calibration parameter in calibration step 36. This further calibration step 38 is performed with a time interval of 22 after calibration step 36, see [reference]. Fig. 3 The calibration parameter influences a combustion parameter of the flame 14. The calibration parameter is defined as a further pulse height 58' of the mixture ratio 54. The mixture ratio 54 of the fuel-oxygen mixture is adjusted by this further pulse height 58'. In the subsequent calibration step 38, the further pulse height 58' is reduced by 5% compared to the pulse height 58 in calibration step 36, provided that calibration step 36 was successfully performed (see figure). Fig. 3 When the burner device 12 is switched on or when an operating point of the burner device 12 is changed, a start value is specified for the pulse height 58' of a further calibration step 38, 40. The start value is configured as a standard value. Alternatively, the start value of the further calibration step 38, 40 for the pulse height 58' is determined by relating the pulse height 58 of the last successful calibration step to a standard value.

[0023] In a further calibration step 40, the pulse height 58 is increased by 10% compared to the pulse height 58 from calibration step 36 if calibration step 36 was unsuccessful. If calibration step 36 was unsuccessful, the time interval 22 of the further calibration step 40 to calibration step 36 is reduced by 80%. If calibration step 36 was unsuccessful, the time interval 22 of the further calibration step 40 to calibration step 36 is reduced to a value of 20%. Alternatively, the time interval could also be reduced by only 50%.

[0024] In evaluation step 42, the measurement signal 56 is evaluated. Calibration step 36 and / or the subsequent calibration steps 38, 40 are completed successfully if two combustion maxima 20 are detected. Calibration step 36 and / or the subsequent calibration steps 38, 40 are completed unsuccessfully if only one combustion maximum 20 is detected in the subsequent calibration steps 38, 40. Calibration steps 38, 40 and evaluation step 42 are repeated iteratively during operation of the burner device 12.

[0025] The Figur 3Figure 1 shows a schematic calibration diagram. The schematic calibration diagram shows a schematic curve of the measurement signal 56 from the ionization sensor 52. Furthermore, the schematic calibration diagram shows a schematic curve of a fuel-oxygen mixture ratio 54 over a calibration period 50. The schematic calibration diagram shows a calibration pulse 60. During the calibration pulse 60, the mixture ratio 54 is set to rich. The schematic calibration diagram has an ordinate 46. The measurement signal 56 from the ionization sensor 52 is plotted on the ordinate 46. The measurement signal 56 is represented as the ionization current detected by the ionization sensor 52. The pulse height 58 of the mixture ratio 54 is plotted on the ordinate 46. The mixture ratio 54 of the fuel-oxygen mixture is also plotted on the ordinate 46. The schematic calibration diagram has an abscissa of 48.A time is plotted on the abscissa 48. A pulse duration 44 of the calibration pulse 60 is plotted on the abscissa 48. The pulse duration 44 of the calibration pulse 60 is 0.1 s. It is conceivable that the pulse duration 44 is more or less than 0.1 s. The pulse duration 44 depends, for example, on the mixing ratio 54 of the fuel-oxygen mixture during normal operation.

[0026] The combustion maximum 20 of the flame 14 occurs at a time offset from the pulse duration 44. The measurement signal 56 of the ionization sensor 52 is generated after the pulse duration 44. The total calibration duration 50 of calibration step 36 or the subsequent calibration steps 38, 40 is 1 s. The total calibration duration 50 is less than 10 s in each calibration process. The total calibration duration 50 is at least twice the pulse duration 44 in each calibration process.

[0027] The schematic calibration diagram shows the time interval 22. Calibration step 36 and the subsequent calibration steps 38 and 40 have a time interval of 22. The subsequent calibration step 38 and 40 includes another calibration pulse 60' with a further pulse height of 58'. The time interval 22 between calibration pulse 60 and the subsequent calibration pulse 60' is 30 s for a successful calibration step. Alternatively, the time interval 22 could also be more or less than 30 s. The time interval 22 between the end of calibration pulse 60 and the start of the subsequent calibration pulse 60' is 6 s for an unsuccessful calibration step. The time interval 22 between calibration step 36 and the subsequent calibration step 38 is 30 s. The time interval 22 between calibration step 36 and the subsequent calibration step 40 is 6 s. This corresponds to 20% of the time interval 22 between calibration step 36 and the subsequent calibration step 38.In a stable calibration process, every second successful calibration step is followed by an unsuccessful calibration step.

Claims

1. A method for calibrating a flame monitoring device (10), in which a fuel is supplied to a burner device (12) to generate a flame (14), and in which an ambient air flow (16) is supplied to the burner device (12) to generate a fuel-oxygen mixture, wherein in at least one calibration step (36) a combustion maximum (20), in particular in the case of stoichiometric combustion, of the flame (14) is exceeded, and wherein at least one further calibration step (38, 40) is carried out at a regular time interval (22), characterized in that in the at least one further calibration step (38, 40) at least one calibration parameter which influences at least one combustion parameter of the flame (14) is automatically adapted compared to the at least one calibration step (36).

2. Method according to claim 1, characterized in thatthe calibration parameter is designed at least as a pulse height (58) with which a mixing ratio (54) of the fuel-oxygen mixture is set.

3. Method according to claim 1 or 2, characterized in that the pulse height (58) for the at least one further calibration step (38, 40) is reduced, in particular by at most 5%, compared to the at least one calibration step (36) if the at least one calibration step (36) has been successfully carried out.

4. Method according to one of the preceding claims, characterized in that the pulse height (58) for the at least one further calibration step (38, 40) is increased, in particular by a maximum of 10%, compared to the at least one calibration step (36) if the at least one calibration step (36) was carried out unsuccessfully.

5. Method according to one of the preceding claims, characterized in thatthe time interval (22) of the at least one further calibration step (38, 40) to the at least one calibration step (36) is reduced, in particular by at least 50%, preferably at least 80%, if the at least one calibration step (36) is aborted unsuccessfully.

6. Method according to one of the preceding claims, characterized in that a starting value for the pulse height (58) is specified, which is set, for example, when switched on or when an operating point is changed.

7. Method according to one of the preceding claims, characterized in that the starting value for the pulse height (58) is determined by relating the pulse height (58) of the last successful calibration step (36, 38, 40) to at least one standard value.

8. Burner device (12), in particular for a hot water heater, with at least one flame monitoring device (10) for carrying out a method according to one of the preceding claims.

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