Method for operating a burner device

Abstract

The invention relates to a method for operating a burner device, wherein an ignition voltage is generated by an ignition transformer (1), same is measured at the ignition transformer (1) and transmitted to an ignition electrode (2) for igniting a flame. According to the invention, after ignition of the flame, using the ignition transformer (1), a monitoring voltage below the ignition voltage is generated, same is transmitted to the ignition electrode (2) functioning as a monitoring electrode, and measured for the purpose of flame monitoring at the ignition transformer (1).

Description

[0001] Method for operating a burner device

[0002] The invention relates to a method for operating a burner device according to the preamble of patent claim 1.

[0003] A device for carrying out a method of the type mentioned at the outset is known from patent document DE 10 2020 107 735 A1 (also filed by the applicant). 10 In this device, an ignition voltage is generated using an ignition transformer. This voltage is measured at the ignition transformer and transmitted to an ignition electrode to ignite a flame. To monitor the burning flame, this solution uses a so-called ionization electrode, which is not explicitly described in the document but is known to the applicant. 15 This solution has an ignition electrode on the one hand and an ionization electrode on the other.

[0004] The invention is based on the object of improving a method of the type mentioned above. In particular, a method is to be created in which the existing ignition transformer and the existing ignition electrode are used even more effectively.

[0005] 25 This object is achieved by a method of the type mentioned at the outset by the features set out in the characterising part of patent claim 1.

[0006] According to the invention it is therefore provided that after ignition of the 30 flame with the ignition transformer a monitoring voltage below the ignition voltage is generated, this is transmitted to the ignition electrode acting as a monitoring electrode and is measured for flame monitoring at the ignition transformer.

[0007] In other words , the method according to the invention is characterized in that the ignition electrode is used not only for igniting the burner device but also for monitoring the ignited flame .

[0008] Other advantageous developments of the method according to the invention emerge from the dependent patent claims. 10

[0009] The method according to the invention, including its advantageous developments according to the dependent claims, is explained in more detail below with reference to the drawing of a preferred embodiment. 15

[0010] It shows schematically

[0011] Figure 1 is a circuit diagram illustrating the method according to the invention. 20

[0012] The circuit diagram shown in Figure 1 illustrates a possible implementation of the method according to the invention. In this case, an ignition voltage is first generated in a manner known per se using an ignition transformer 1. This is then also measured at the ignition transformer 1 (arrow 15) and transmitted to an ignition electrode 2 (see arrow 11) to ignite a flame. In this case, it is further preferably provided that the ignition electrode 2 is optionally operated with a voltage between 0.8 and 25 kV and / or is formed from two electrode wires (known per se, not shown separately). In this case, it is also particularly preferably provided that the ignition of the flame is carried out at a constant air volume flow to the burner device.

[0013] Essential to the method according to the invention is that, after ignition of the flame, a monitoring voltage below the ignition voltage is generated by the ignition transformer 1. This monitoring voltage is transmitted to the ignition electrode 2 acting as a monitoring electrode (arrow 11), and measured for flame monitoring at the ignition transformer 1 (arrow 15). As already explained at the beginning, this makes it possible to use the ignition electrode 2 as a monitoring electrode.

[0014] It is particularly preferred that the ignition transformer 1 is provided with a pulse width modulation generator

[0015] 3 (see arrow 15 12). The pulse width modulation generator 3 itself is preferably operated with alternating voltage (arrow 18). Furthermore, it is preferably provided that the pulse width modulation generator 3 is controlled by a control device 4 (see arrows 13 and 14). 20

[0016] Furthermore, it is preferably provided that the pulse-width-modulated ignition voltage at the ignition transformer 1 is measured with a voltage measuring device (see arrow 15 again). Looking at it in more detail, it is further preferably provided that the monitoring voltage measured at the ignition transformer 1 is forwarded as a measurement signal to the control device 4 (see arrows 15 and 16). Furthermore, it is preferably provided that the monitoring voltage measured at the ignition transformer 1 is supplied via a sample-and-hold circuit 30 5 (see in particular https: / / de.wikipedia.org / wZin- dex . php ? title=Sample-and-Hold-Schal tung&oldid=219320546 ) to

[0017] Control device 4 is passed on.

[0018] Furthermore, it is preferably provided that the control device 4 generates a flame monitoring signal (see arrow 17) based on measurement signals from the ignition transformer 1 and 5 from the pulse width modulation generator 3. This is preferably provided by the control device 4 in the form of an electrical voltage between 0 and 10 V.

[0019] 10

[0020] Furthermore, it is preferably provided that a gas containing at least a portion of hydrogen is burned with the burner device. Looking at it in more detail, it is particularly preferably provided that a gas containing at least 20 vol . -% hydrogen is burned with the burner device. 15

[0021] Expressed in other words, the method according to the invention is characterized in particular as follows:

[0022] The burner is started by preferably initially supplying a constant air volume flow to the combustion system. The ignition is then switched on, causing high-voltage discharges above the minimum ignition energy of the fuel gas-air mixture between the electrodes (wires). Within a few milliseconds, the resulting plasma of the ionized air reaches the maximum breakdown voltage, which is output on the primary side of the ignition transformer 1 in the form of a voltage signal. If "reliable" ignition is guaranteed, the gas valve is opened and the gas control valve is moved according to the characteristic curve (so-called gas ramp). After the fuel gas-air mixture has left the combustion chamber orhas reached the electrodes, thermo-chemical, predominantly exothermic reactions start immediately which, after the ignition delay time has elapsed, lead to self-sustaining flame propagation within the ignition limits of the respective fuel gas-air mixture. The conductivity of the flame leads to a drop in the breakdown voltage, 5 which in turn is used by the voltage signal coupled out on the primary side for flame detection with corresponding stopping of the gas ramp of the gas control valve. After the safety time has elapsed, the voltage is regulated by the ignition transformer below the breakdown 10 voltage, in particular by pulse width modulation, so that in the event of a flame loss or flame displacement, no ignition spark is created between the electrodes (falling below the minimum ignition energy). The electrical conductivity of the flame can be measured using the applied alternating voltage.In addition, the proportion of hydrocarbons in the fuel gas-air mixture is in direct correlation with the rectifying effect of the alternating electrical voltage, so that flame monitoring via ionization current is also possible.

[0023] List of reference symbols

[0024] 1 ignition transformer

[0025] 2 ignition electrodes

[0026] 3 Pulse width modulation generator

[0027] 4 Control device

[0028] 5 Sample and hold circuit

[0029] 11 to 18 arrow

Claims

Patent claims 1. Method for operating a burner device in which an ignition voltage is generated with an ignition transformer (1), this is measured at the ignition transformer (1) and is transferred to an ignition electrode (2) to ignite a flame, characterized in that after ignition of the flame with the ignition transformer (1) a monitoring voltage below the ignition voltage is generated, this is transferred to the ignition electrode (2) which acts as a monitoring electrode and is measured at the ignition transformer (1) for flame monitoring.

2. Method according to claim 1, characterized in that the ignition transformer (1) is operated with an electrical voltage generated by a pulse width modulation generator (3).

3. Method according to claim 2, characterized in that the pulse width modulated ignition voltage at the ignition transformer (1) is measured with a voltage measuring device.

4. Method according to claim 2 or 3, characterized in that the pulse width modulation generator (3) is controlled by a control device (4). A method according to claim 4, characterized in that the monitoring voltage measured at the ignition transformer (1) is forwarded as a measurement signal to the control device (4). A method according to claim 4 or 5, characterized in that the monitoring voltage measured at the ignition transformer (1) is routed to the control device (4) via a scan-and-hold circuit (5). A method according to claims 2 and 4, characterized in that the control device (4) generates a flame monitoring signal based on measurement signals from the ignition transformer (1) and the pulse width modulation generator (3). A method according to claim 7, characterized in that the flame monitoring signal is provided by the control device (4) in the form of an electrical voltage between 0 and 10 V. A method according to any one of claims 1 to 8, characterized in that a gas containing at least a proportion of hydrogen is combusted with the burner device. The method according to claim 9, characterized in that a gas with at least 20 vol% hydrogen is burned with the burner device.

Images