Method and burner device

Abstract

The invention relates to a method for calibrating a flame monitoring device (10) for a burner device that can be operated at a predetermined power output, in which fuel is supplied to the 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 (38, 40) a combustion maximum (20) of the flame (14) is exceeded, in which a rich fuel-oxygen mixture is generated at least in the calibration step (38, 40) for a predetermined calibration duration (84) and / or a pulse duration (44). A change in power output during calibration, limited over a predetermined duration (82), is proposed.The invention also relates to a burner device (12) which is at least configured to calibrate the flame monitoring device (10) using the method according to one of claims 1-6.

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 a combustion maximum of the flame is exceeded in at least one calibration step. Disclosure of the invention

[0002] The invention relates to a method for calibrating a flame monitoring device for a burner device that can be operated at a predetermined power, in which a fuel is supplied to the 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 of the flame is exceeded, in which at least in the calibration step a rich fuel-oxygen mixture is generated for a predetermined pulse duration.

[0003] The method is characterized by a change in performance during calibration that is limited over a predetermined period of time.

[0004] The inventive design of the method advantageously provides a high level of convenience, as temperature fluctuations can be reduced / limited, particularly during the calibration step. By varying the power output over a specific period of time, specifically during the calibration process, the operation of the burner device and the calibration process are prevented from interfering with each other, or at least minimized. Such interference can lead to resonances. Resonances can be mitigated or even completely avoided with the proposed method.

[0005] A duration is understood to mean that the step or process is limited in time. It refers to a specific period of time during operation, particularly continuous operation of the burner device, within which the defined duration falls. This duration has a start time and a subsequent end time. Continuous operation is understood to mean operation during which the burner device operates under normal conditions. This can be at a constant power output or at a power output adjusted to normal use. Changing the power output during calibration over a predetermined period differs from normal use in this sense. The change is determined by the requirements of the calibration process. Current performance data from normal use can be taken into account when making this change.

[0006] 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 and / or boiler. 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 fuel is designed as a fuel 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, particularly in the burner, is mixed with the ambient air stream. Preferably, a fuel-oxygen mixture is generated. The fuel-oxygen mixture has a specific mixing ratio. This 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 mixture 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, configured to measure an ionization current. Specifically, an electrical voltage is applied to the flame, for example, between the housing and the ionization sensor, from which the ionization current is generated, particularly when a flame is present. Preferably, the ionization current depends at least on a certain flame intensity. Preferably, the ionization current increases with the flame intensity.Preferably, the ionization current is at least substantially maximal at the combustion maximum. Preferably, the ionization current decreases as the flame intensity decreases when the combustion maximum is exceeded, which occurs particularly with a rich fuel-oxygen mixture. 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.

[0007] Preferably, the fuel-oxygen mixture is enriched until the combustion maximum of the flame is exceeded. Preferably, the ion formation rate in the flame is at least substantially maximal at the combustion maximum. Preferably, the fuel-oxygen mixture is burned stoichiometrically at the combustion maximum. In particular, the combustion temperature is maximal at least substantially at the combustion maximum. In particular, the combustion maximum must be exceeded in order to identify it. Preferably, the rich fuel-oxygen mixture is burned, especially along an increasing mixture ratio, in which at least one calibration step occurs at least substantially above the combustion maximum.

[0008] Preferably, the calibration step comprises at least one pulse step and one evaluation step. Preferably, in the pulse step, the mixture ratio of the fuel-oxygen mixture is increased over a pulse duration, particularly of less than 5 s, preferably less than 1 s, and preferably less than 0.5 s. Preferably, in the evaluation step, following the pulse step, at least one pulse response is measured and evaluated over an evaluation period. Preferably, the evaluation period is at least substantially the same length as the pulse duration. Preferably, the total duration of the calibration step is less than 20 s, more preferably less than 10 s. In particular, the total duration of the calibration step is at least twice the pulse duration.In this context, "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 is understood to mean, 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.

[0009] Advantageous further developments of the method according to the main claim are possible due to the features listed in the dependent claims. It is proposed, for example, that the time duration be greater than the pulse duration. This allows for an optimized time window to be provided for adjusting the power of the burner device. Although coordinated, the calibration process and the power change can each be optimized to suit specific requirements.

[0010] If the period during which the power is changed begins before the pulse duration, the burner can be controlled and returned to the limited power change. If the period during which the power is changed ends after the pulse duration, the burner can be controlled and returned to the power used in normal operation.

[0011] Changing the power output should ensure that calibration does not affect normal operation. This is advantageously achieved by reducing and / or increasing the power output. Reducing the power output is advantageously accomplished by reducing the blower speed and decreasing the fuel valve opening. Increasing the power output is advantageously accomplished by increasing the blower speed and increasing the fuel valve opening. If it is found that simply reducing or increasing the power output does not resolve a resonance conflict, it is possible to deliberately vary the power output from a reduction to an increase, or vice versa.

[0012] Advantageously, the power output is changed in such a way that both the fuel supplied and the ambient air supplied are reduced.

[0013] It is proposed that the temporal variation of the power output be achieved by means of software that controls or regulates the burner device.

[0014] Furthermore, it is proposed that the temporal variation of the power output is part of a calibrating, controlling, or regulating software module.

[0015] A preferred embodiment is a burner device comprising at least one flame monitoring device with at least one blower configured to supply an ambient airflow to the burner, at least one fuel supply valve configured to adjust the fuel quantity, and at least one control and / or regulating unit configured to calibrate the flame monitoring device using the method according to the invention. Advantageously, a high level of user comfort can be provided, as temperature fluctuations can be reduced / limited, particularly during the calibration step. Advantageously, a cost-effective design can be provided, as no additional components are required to implement the method. Preferably, the flame monitoring device includes at least one ionization sensor.

[0016] In a simple process, the ambient airflow is advantageously reduced in at least one calibration step for generating the rich fuel-oxygen mixture. A high level of comfort can be advantageously provided, as temperature fluctuations can be reduced / limited, in particular, by reducing the ambient airflow. Preferably, the rich fuel-oxygen mixture is generated by reducing the oxygen content of the fuel-oxygen mixture. Specifically, the rich fuel-oxygen mixture is generated by increasing the mixing ratio. Preferably, the ambient airflow is reduced by supplying less ambient air to the burner with the same amount of fuel. For example, the ambient airflow could be reduced by decreasing the cross-sectional area of ​​an ambient air duct in the burner assembly. Alternatively, a bypass valve could be opened.

[0017] Furthermore, it is advantageous to generate the rich fuel-oxygen mixture by reducing the blower speed. A cost-effective design can be provided, as no additional components are required, particularly for calibration. Preferably, the blower speed is reduced by specifying at least one reduced blower speed and a duration for that reduced speed. It is conceivable that a duration, particularly a maximum duration, is specified for the reduction of the blower speed. Specifically, the blower speed is not reduced below a minimum during at least one calibration step. For example, the difference between the initial speed and the reduced speed could be defined as a pulse height.For example, the time between the start time of the reduction of the fan speed and reaching the reduced fan speed could be designed as a holding time.

[0018] 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, comprise 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

[0019] 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.

[0020] They show: Fig. 1 a burner device with a flame monitoring device, Fig. 2 a schematic flowchart of a method for calibrating the flame monitoring device, Fig. 3 a schematic calibration diagram and Fig. 4 diagrams of time courses of a calibration process. Description of the exemplary embodiment

[0021] The Figure 1 Figure 1 shows a burner device 12. The burner device 12 is designed to heat water in an instantaneous water heater or boiler or the like.

[0022] 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, see figure. Fig. 3 The measurement signal is in the form of an ionization current.

[0023] The burner assembly 12 includes a blower 26. The burner assembly 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.

[0024] The burner device 12 has a fuel supply valve 30. The fuel supply valve 30 is configured to supply fuel to the burner 28. The fuel is in the form of a fuel gas. The fuel gas could be natural gas, methane, hydrogen, or the like. The fuel supply valve 30 is configured to adjust a fuel supply 34.

[0025] The burner 28 has a fuel-oxygen mixture. The fuel-oxygen mixture has a mixing ratio of 54, see [reference]. Fig. 3 The mixture ratio 54 is defined as the ratio of fuel to oxygen. The burner 28 is designed to burn the fuel-oxygen mixture. The burner 28 is designed to produce a flame 14.

[0026] 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 designed as a gas cylinder. However, the fuel tank 18 could also be designed as a public fuel network or the like.

[0027] The Figure 2 shows a schematic flowchart of a procedure for calibrating the flame monitoring device 10.

[0028] In at least one preparatory step 36, an operating parameter is determined. The operating parameter is retrieved / read by the control unit 32. The operating parameter is configured as a fan speed. Alternatively or additionally, the operating parameter could be configured as a pressure in a combustion chamber 22 of the burner device 12 and / or in the ambient air duct 24 of the burner device 12. Alternatively or additionally, the operating parameter could also be configured as a mixture ratio 54 of the fuel-oxygen mixture during normal operation of the burner device 12. The operating parameter has a limit value. Based on the limit value, a decision is made as to whether a further calibration step 38 or a further calibration step 40 is performed.

[0029] In at least one further calibration step 38, a calibration pulse 60 is generated, cf. Fig. 3The calibration pulse 60 is generated by setting a rich fuel-oxygen mixture ratio 54. In the exemplary embodiment according to Figure 3A rich fuel-oxygen mixture is generated for a pulse duration 44 of 0.1 s. Alternatively, the pulse duration 44 could also be greater than 0.1 s. The rich fuel-oxygen mixture is set based on a pulse height 58 of the calibration pulse 60. The fuel-oxygen mixture is enriched from a normal operating state. In the exemplary embodiment, the ambient airflow is reduced to generate the rich fuel-oxygen mixture. The ambient airflow is reduced by decreasing the blower speed. The ambient airflow is reduced to enrich the fuel-oxygen mixture when the operating parameter is at least at the limit value. After the pulse duration 44 of 0.1 s, the ambient airflow is reset to the value of the normal operating state. In at least one calibration step 38, the fuel supply 34 is kept constant.

[0030] In at least one further calibration step 40, if the limit value is undershot, the rich fuel-oxygen mixture is produced by increasing the fuel supply 34, cf. Fig. 1 In at least one further calibration step 40, it is ensured that the mixing ratio 54 can be increased sufficiently in each calibration state to achieve a combustion maximum 20 of the flame 14. In at least one further calibration step 40, the blower speed is kept constant. In at least one further calibration step 40, the ambient airflow 16 is kept constant.

[0031] In at least one evaluation step 42, the combustion maximum 20 of the flame 14 is detected. The detected measurement signal 56 is evaluated by the control unit 32. The combustion maximum 20 of the flame 14 is reached after the pulse duration 44 has elapsed. The combustion maximum 20 is generated with a time offset from the calibration pulse 60. Alternatively, it is conceivable that the combustion maximum 20 of the flame 14, for example with a long pulse duration 44, is reached during the calibration pulse 60.

[0032] The Figure 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 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 fuel-oxygen mixture ratio 54 is also plotted on the ordinate 46. The schematic calibration diagram has an abscissa 48. Time is plotted on the abscissa 48. The calibration pulse 60 has a pulse height 58 corresponding to the mixture ratio 54. 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 can have different values. Once preselected, it is fixed. It can be preselected depending on various influences and parameters. Such influences and parameters include, for example, the fuel-oxygen mixture ratio 54 during normal operation or the current power output. The pulse duration 44 is less than 2 s in every calibration state. The pulse duration should be set or preselected as short as possible.

[0033] Alternatively, the pulse duration 44 is less than 5 s in each calibration state. 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 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. 60' and 58' denote the next calibration process.

[0034] In the exemplary embodiment according to Figure 4 During calibration, the power output of the burner device 12 is changed. Figure 4 This is one such calibration process. In contrast to the embodiment shown below. Figure 3The calibration process is not carried out over a pulse duration 44, but rather as a continuous process. This can occur during calibration step 38 or during calibration step 40. The first diagram curve 70 shows the power at which the burner device 12 is operated. Diagram curve 72 shows the position of the fuel supply valve 30. Diagram curve 74 shows the blower speed. Diagram curve 76 shows the measurement signal 56 of the ionization sensor 52.

[0035] In this embodiment, a calibration process is triggered at time t1. For this purpose, the fuel-oxygen mixture is brought into a rich state. The measurement signal 56 of the ion sensor 52 shows a curve as can be seen in the diagram 76. The measurement signal 56 shows the curve with the combustion maximum 20.

[0036] According to the invention, the power is varied during calibration. This is shown by the diagram curve 70. At time t 1, the power is reduced from level 80 and then increased again to level 80, reaching it again at time t 2. The time interval 82 between times t 2 and t 1 is the period during which a limited change in power takes place.

[0037] The power reduction is achieved by slightly closing the fuel supply valve 30. This is evident in diagram curve 72 as a drop in the curve starting at time t1. The blower speed is also reduced accordingly. This is shown by line 78 in diagram curve 74.

[0038] In the exemplary embodiment, the calibration process is also started at time t1. To achieve a fuel surplus, i.e., a rich mixture, the blower speed is reduced more than is necessary for the power reduction. This is represented by a dashed line 84 in diagram 74.

[0039] A rich mixture can also be produced by slightly reducing the opening of the fuel supply valve 30. This reduces the effect on the burner device 12.

[0040] In the exemplary embodiment, the calibration period 84 is approximately the same length as the period 82 for changing the power. However, in variants, the period 82 for changing the power can also be longer than the calibration period 84. If, according to the embodiment, Figure 3If the calibration process is carried out using a pulse, the time period 82 for the change in power is greater than the pulse duration 44. Depending on the resonance behavior, the time periods 82 for the change in power and the calibration period 84 and / or the pulse duration 44 overlap.

[0041] The time period 82 for the power change can be greater than the calibration time period 84 and / or the pulse duration 44.

[0042] In one variant, the time t 1 ' for the power reduction is before the time t 1 for the calibration.

[0043] In another variant, the time t 2 ' for the power reduction is after the time t 2 for the calibration.

[0044] In another variant, the time t 1 ' for the power reduction is before the time t 1 for the calibration, and the time t 2 ' for the power reduction is after the time t 2 for the calibration.

[0045] In the exemplary embodiment, the power output is reduced for a period of time 82. This is used, for example, when the burner is operated at a high power output when the calibration process is started. However, it is also possible to increase the power output. This is used, for example, when the burner is operated at a low power output. It is also possible to design the burner's power output to be alternating. The essential point, however, is that the calibration process, and thus the measurement signal 56, is generated in a way that allows for evaluation. Evaluation is most successful when the combustion maximum 20 is clearly identifiable. However, a different curve can also be generated and used, provided that it has been determined and stored in advance, for example, in laboratory tests.

[0046] In the exemplary embodiment, the method is carried out by software that controls or regulates the burner device 12, thereby changing the power output over time. This software can be stored in a central control unit 32. The software can also be operated via a cloud or in a combination of both.

[0047] The method is characterized by the fact that changing the power over time can be part of a software module that controls or regulates the calibration.

Claims

1. Method for calibrating a flame monitoring device (10) for a burner device operable at a predetermined power, in which a fuel is supplied to the 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 (38, 40) a combustion maximum (20) of the flame (14) is exceeded, in which at least in the calibration step (38, 40) a rich fuel-oxygen mixture is generated for a predetermined calibration time (84) and / or a pulse duration (44), characterized by a change in performance during calibration limited over a predetermined period of time (82).

2. Method according to claim 1, characterized by the fact that the time duration is greater than the calibration time duration (84) and / or the pulse duration (44).

3. Method according to claim 1 or 2, characterized by the fact that the time period (82) begins before the calibration time period (84) and / or the pulse duration (44) and / or ends after the calibration time period (84) and / or the pulse duration (44).

4. Method according to any one of the preceding claims, characterized by the fact that Changing this reduces and / or increases performance.

5. Method according to any one of the preceding claims, characterized by the fact that The change in performance is achieved by reducing both the amount of fuel supplied and the amount of ambient air supplied.

6. Method according to any one of the preceding claims, characterized by the fact that in which at least one calibration step (38) to generate the rich fuel-oxygen mixture reduces the ambient airflow (16).

7. Method according to any of the preceding claims, characterized by the fact thatThe change in power over time is achieved by means of software that controls or regulates the burner device (12).

8. Method according to any one of the preceding claims, characterized by the fact that The temporal variation of the power output is part of a software module that controls or regulates the calibration.

9. Burner device (12) with at least one flame monitoring device (10) with at least one blower (26) which is configured to supply an ambient air flow (16) to a burner (28), with at least one fuel supply valve (30) which is configured to adjust a fuel quantity, and with at least one control and / or regulating unit (32) which is configured at least to calibrate the flame monitoring device (10) by means of the method according to one of claims 1-6.

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