Method 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 a combustion maximum (20) of the flame (14) is exceeded in at least one calibration step (18). It is proposed that a rich fuel-oxygen mixture is generated in the at least one calibration step (18) for a pulse duration (44) of less than 5 s.

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 flow 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 is based on 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 flow 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.

[0003] It is proposed that in the at least one calibration step, a rich fuel-oxygen mixture is generated over a pulse duration of less than 5 s.

[0004] The inventive design of the method advantageously provides a high level of comfort, since temperature fluctuations can be reduced / limited, particularly during the calibration step. Advantageously, high operational reliability / calibration efficiency can be provided, since the calibration step, in particular, is carried out quickly due to the pulse duration of less than 5 seconds. Advantageously, a low-cost design can be provided, since no additional components need to be installed, especially to carry out the method.

[0005] The flame monitoring device preferably has at least one ionization sensor. Alternatively or additionally, the flame monitoring device could also have at least one lambda probe or a temperature sensor and / or a comparable direct and / or indirect measuring method for measuring the combustion quality. The burner device is preferably designed as a continuous-flow heater and / or boiler. In particular, water is heated by the burner device. Thermal energy is preferably supplied to the water by the burner device, in particular a burner of the burner device. The thermal energy is preferably generated by the flame. The fuel is preferably designed as a combustion fluid, in particular as a combustion 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 comprises at least oxygen. Preferably, the ambient air stream is generated by a fan sucking in ambient air. Preferably, the ambient air stream is introduced into the burner of the burner device. Preferably, the fan generates a pressure in the burner that is greater than the ambient pressure. Preferably, the fuel, in particular in the burner, is mixed with the ambient air stream. Preferably, a fuel-oxygen mixture is generated. The fuel-oxygen mixture has a mixing ratio. The mixing ratio is formed 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 in particular to mean a mixing ratio that contains less oxygen than is required for complete combustion / oxidation of the fuel. An "ionization sensor" is understood in particular to mean 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 in the presence of a flame. The ionization current preferably depends at least on the flame intensity. The greater the flame intensity, the greater the ionization current.Preferably, the ionization current is at least substantially at its maximum 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 achieved at least substantially at a stoichiometric mixture ratio. For example, the flame intensity is lower with a leaner and / or richer fuel-oxygen mixture than at the combustion maximum with stoichiometric combustion. "Stoichiometric" is understood in particular to mean a fuel-oxygen mixture that contains exactly the same amount of oxygen as theoretically required for the oxidation of the fuel contained in the fuel-oxygen mixture.

[0006] Preferably, the fuel-oxygen mixture is enriched / enriched until the combustion maximum of the flame is exceeded. Preferably, an ion formation rate in the flame is at least substantially maximum at the combustion maximum. Preferably, the fuel-oxygen mixture is burned stoichiometrically at the combustion maximum. In particular, the combustion temperature is at least substantially maximum at the combustion maximum. In particular, the combustion maximum must be exceeded in order to be able to identify the combustion maximum. Preferably, the rich fuel-oxygen mixture is burned at least substantially above the combustion maximum in the at least one calibration step, in particular along an increasing mixing ratio.

[0007] The calibration step preferably comprises at least one pulse step and one evaluation step. Preferably, in the pulse step, at least the mixing ratio of the fuel-oxygen mixture is increased over a pulse duration, in particular 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 duration. Preferably, the evaluation duration is at least substantially the same length as the pulse duration. Preferably, the total duration of the calibration step is less than 20 s, preferably less than 10 s. In particular, the total duration of the calibration step is at least twice the pulse duration.A "combustion maximum" is understood in particular to mean 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 in particular to mean a deviation from a predetermined value of, in particular, less than 25%, preferably less than 10%, and particularly preferably less than 5% of the predetermined value.

[0008] It is further proposed that in the at least one calibration step for generating the rich fuel-oxygen mixture, the ambient air flow is reduced. Advantageously, a high level of comfort can be provided, since, in particular, temperature fluctuations can be reduced / limited by reducing the ambient air flow. Preferably, the rich fuel-oxygen mixture is generated by reducing the oxygen content of the fuel-oxygen mixture. In particular, the rich fuel-oxygen mixture is generated by increasing the mixing ratio. Preferably, the ambient air flow is reduced by supplying less ambient air to the burner for the same amount of fuel. For example, the ambient air flow could be reduced by reducing the flow cross-section of an ambient air duct of the burner device. Alternatively, a bypass valve could also be opened.

[0009] Furthermore, it is proposed that the rich fuel-oxygen mixture is generated by reducing a fan speed. Advantageously, a low-cost design can be provided, particularly since no additional components need to be installed to carry out the calibration. Preferably, the fan speed is reduced by specifying at least one reduced fan speed and a time duration for the reduced fan speed. It is conceivable that a time duration, in particular a maximum time duration, is specified for the reduction of the fan speed, in which the speed change is carried out. In particular, in the at least one calibration step, the fan does not fall below a minimum fan speed. For example, a difference between an initial speed and the reduced speed could be designed as a pulse height.For example, the time period between a start time of the reduction of the fan speed and reaching the reduced fan speed could be designed as a holding time.

[0010] Furthermore, it is proposed that in at least one preparatory step, at least one operating parameter be determined which has at least one limit value below which the rich fuel-oxygen mixture is generated by increasing the fuel supply. Advantageously, a high level of operational reliability / calibration reliability can be provided, since, in particular, by taking the operating parameter into account, calibration can be carried out in any operating state. Preferably, the operating parameter is designed as a mixture ratio. In particular, with a very lean fuel-oxygen mixture, for example with a mixture ratio at a limit value with a lambda value of less than 0.5, the rich fuel-oxygen mixture could be achieved by increasing the fuel supply.In particular, with a lean to rich fuel-oxygen mixture, for example, a mixture ratio at a limit value with a lambda value of 0.5 and less than 1, the rich fuel-oxygen mixture could be achieved by increasing the fuel supply. Depending on the limit value, either the fan speed or the fuel supply is preferably kept at least essentially constant. A "lambda value" is understood in particular to mean a fuel-to-oxygen ratio that is related to a stoichiometric fuel-to-oxygen ratio.

[0011] It is further proposed that the operating parameter be embodied at least as a fan speed. Advantageously, a particularly low level of complexity can be provided since, in particular, the fan speed is already known and only needs to be read out. To generate the rich fuel-oxygen mixture, a fuel supply is preferably increased if a limit value for the fan speed is undershot. To generate the rich fuel-oxygen mixture, the fan speed is preferably reduced if the reduction in the fan speed does not result in the fan speed falling below a limit value. In particular, the limit value for the fan speed ensures that the fan is operated at at least a minimum fan speed in every calibration state.

[0012] It is additionally proposed that the operating parameter be embodied at least as a pressure in a combustion chamber and / or the ambient air duct of the burner device. Advantageously, a high level of operational reliability / calibration reliability can be provided since, in particular, by taking the operating parameter into account, calibration can be carried out in any operating state. Preferably, the pressure in the combustion chamber and / or the ambient air duct is embodied as a differential pressure between the pressure in the combustion chamber and / or the ambient air duct and a pressure in a fuel supply line and / or in a fuel tank, such as a gas cylinder. Alternatively, the pressure in the combustion chamber and / or the ambient air duct could be embodied as an absolute pressure or as a differential pressure to an ambient pressure. It is conceivable that the operating parameter takes into account at least a fill level of the fuel tank.

[0013] In addition, a burner device with a flame monitoring device is proposed, which has at least one fan configured to supply an ambient air flow to a burner, with at least one fuel supply valve configured to adjust a fuel quantity, and with at least one control and / or regulating unit configured at least to calibrate the flame monitoring device using the method. Advantageously, a high level of comfort can be provided, since temperature fluctuations can be reduced / limited, particularly during the calibration step. Advantageously, a low-cost construction can be provided, since no additional components need to be installed, particularly to carry out the method. The flame monitoring device preferably has at least one ionization sensor.

[0014] The calibration method according to the invention and the burner device according to the invention are not intended to be limited to the application and embodiment described above. In particular, the calibration method according to the invention and the burner device according to the invention may have a number of individual elements, components, units, and method steps that differs from the number stated herein to fulfill a function described herein. Furthermore, in the value ranges specified in this disclosure, values ​​within the stated limits are also to be considered disclosed and can be used arbitrarily. drawing

[0015] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an exemplary embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0016] They show: Fig. 1 shows a burner device with a flame monitoring device, Fig. 2 shows a schematic flow diagram of a method for calibrating the flame monitoring device, and Fig. 3 shows a schematic calibration diagram. Description of the embodiment

[0017] The Figure 1shows a burner device 12. The burner device 12 is configured to heat water in a flow heater or boiler or the like. The burner device 12 has a flame monitoring device 10. The flame monitoring device 10 has an ionization sensor 52. The ionization sensor 52 is configured to generate a measurement signal 56, see. Fig. 3The measurement signal is in the form of an ionization current. The burner device 12 has a fan 26. The burner device 12 has a burner 28. The fan 26 is configured to supply an ambient air flow 16 to the burner 28. The burner 28 and the fan 26 are fluidly connected to one another via an ambient air duct 24. The burner device 12 has a fuel supply valve 30. The fuel supply valve 30 is configured to supply a 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. The burner 28 has a fuel-oxygen mixture. The fuel-oxygen mixture has a mixing ratio 54, cf. Fig. 3The mixture ratio 54 is formed 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 has 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. The burner device 12 has 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.

[0018] The Figure 2 shows a schematic flow diagram of a method for calibrating the flame monitoring device 10.

[0019] In at least one preparation step 36, an operating parameter is determined. The operating parameter is retrieved / read out by the control and / or regulating unit 32. The operating parameter is embodied as a fan speed. Alternatively or additionally, the operating parameter could be embodied 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 embodied as a mixture ratio 54 of the fuel-oxygen mixture in a controlled 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 carried out.

[0020] In the at least one further calibration step 38, a calibration pulse 60 is generated, cf. Fig. 3. The calibration pulse 60 is generated by setting a rich mixture ratio 54 of the fuel-oxygen mixture. A 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 fuel-oxygen mixture is set rich using a pulse height 58 of the calibration pulse 60. The fuel-oxygen mixture is enriched from a control mode. To generate the rich fuel-oxygen mixture, the ambient air flow is reduced. The ambient air flow is reduced by reducing the fan speed. The ambient air flow is reduced to enrich the fuel-oxygen mixture if the operating parameter is at least above the limit value. After the pulse duration 44 of 0.1 s, the ambient air flow is reset to the control mode value.In the at least one calibration step 38, the fuel supply 34 is kept constant.

[0021] In the at least one further calibration step 40, if the limit value is undershot, the rich fuel-oxygen mixture is generated by increasing the fuel supply 34, cf. Fig. 1 In the at least one further calibration step 40, it is ensured that the mixture ratio 54 can be increased sufficiently in each calibration state to achieve a combustion maximum 20 of the flame 14. In the at least one further calibration step 40, the fan speed is kept constant. In the at least one further calibration step 40, the ambient air flow 16 is kept constant.

[0022] 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 and / or regulating unit 32. The combustion maximum 20 of the flame 14 is reached after the end of the pulse duration 44. The combustion maximum 20 is generated with a temporal offset from the calibration pulse 60. Alternatively, it is conceivable that the combustion maximum 20 of the flame 14 is reached during the calibration pulse 60, for example, with a long pulse duration 44.

[0023] The Figure 3shows 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 mixing ratio 54 of the fuel-oxygen mixture over a calibration period 50. The schematic calibration diagram has an ordinate 46. The measurement signal 56 of the ionization sensor 52 is plotted on the ordinate 46. The measurement signal 56 is in the form of the ionization current detected by the ionization sensor 52. Furthermore, the mixing ratio 54 of the fuel-oxygen mixture is plotted on the ordinate 46. The schematic calibration diagram has an abscissa 48. A time is plotted on the abscissa 48. The calibration pulse 60 has a pulse height 58 of the mixing 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 depends, for example, on the mixture ratio 54 of the fuel-oxygen mixture during normal operation. The pulse duration 44 is less than 2 s in each calibration state. Alternatively, the pulse duration 44 is less than 5 s in each calibration state. The combustion maximum 20 of the flame 14 occurs with a temporal offset from the pulse duration 44. The measurement signal 56 of the ionization sensor 52 is generated subsequent to 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.

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 (38, 40) a combustion maximum (20) of the flame (14) is exceeded, characterized in that in which a rich fuel-oxygen mixture is generated in at least one calibration step (38, 40) over a pulse duration (44) of less than 5 s.

2. Method according to claim 1, characterized in that in which the ambient air flow (16) is reduced in at least one calibration step (38) to produce the rich fuel-oxygen mixture.

3. Method according to claim 1 or 2, characterized in thatthe rich fuel-oxygen mixture is generated in the at least one calibration step (38) by reducing a fan speed.

4. Method according to one of the preceding claims, characterized in that in at least one preparation step (36) at least one operating parameter is determined which has at least one limit value below which the rich fuel-oxygen mixture is produced by increasing the fuel supply (34).

5. Method according to claim 4, characterized in that the operating parameter is at least designed as a fan speed.

6. Method according to claim 4 or 5, characterized in that the operating parameter is designed at least as a pressure in a combustion chamber (22) and / or an ambient air duct (24) of the burner device (12).

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

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