Flame monitoring device for gas burner appliance and gas burner appliance

Abstract

A flame monitoring device (23) for a gas burner appliance (10) configured to burn a combustible gas, the combustion of which generates a flame (12), comprises: a flame monitoring device (24) which provides a voltage signal as a measurement signal depending on the presence of the flame (12); and an electronic circuit (25) which converts the voltage signal provided by the flame monitoring device (24) into a current signal.

Description

Technical Field

[0001] The invention relates to a flame monitoring device for a gas burner appliance and to a gas burner appliance. Background Art

[0002] Gas burner appliances known from the prior art include flame ionization sensors for monitoring the flame generated by the combustion of a combustible gas. EP 2 354 657 A2, EP 2 357 410 B1, and EP 3 059 496 B1 disclose such gas burner appliances including flame ionization sensors. DE 10 2008 005 216 B3 discloses a method for controlling the operation of a gas burner appliance based on an electrical flame ionization current provided by a flame ionization sensor. Such gas burner appliances include a controller that uses the electrical flame ionization current as an input signal.

[0003] Gas burner appliances known from the prior art that include flame ionization sensors require that the combustion of the combustible gas produce a flame with ions. Otherwise, the flame ionization sensor cannot monitor the flame. The combustion of methane as a combustible gas produces a flame with ions. However, the combustion of hydrogen, for example, as a combustible gas, produces a flame without ions. Therefore, field-installed gas burner appliances equipped with flame ionization sensors cannot be used for hydrogen combustion.

[0004] CN 203 162 944U discloses a hydrogen burner apparatus.

[0005] DE 42 28 948 A1 discloses a flame monitoring device for monitoring a burner for shock waves. Summary of the Invention

[0006] Against this background, a novel flame monitoring device for a gas burner appliance is provided, which can also be used for flame monitoring of flames without ions and provides an output signal corresponding to the electrical flame ionization current.

[0007] Furthermore, a gas burner appliance having such a flame monitoring device is provided.

[0008] The flame monitoring device according to the present invention is defined in the claims. The flame monitoring device according to the present invention comprises a flame monitoring device that provides a voltage signal as a measurement signal depending on the presence of a flame. The flame monitoring device also comprises an electronic circuit that converts the voltage signal provided by the flame monitoring device into a current signal. The current signal provided by the electronic circuit corresponds to the flame ionization current. This novel flame monitoring device can be used for flame monitoring of flames without ions.

[0009] The flame monitoring device according to the invention can provide a conversion kit for a gas burner appliance having a flame ionization sensor and a controller adapted to use the flame ionization current provided by the flame ionization sensor as an input signal, i.e. by replacing the flame ionization sensor with the flame monitoring device and by retaining the controller.

[0010] Preferably, the flame monitoring device is a thermocouple. Thermocouples are simple, reliable, and cost-effective. Thermocouples provide a voltage signal depending on the presence of a flame.

[0011] Preferably, the electronic circuit includes: a comparator that compares the voltage signal provided by the flame monitoring device with a nominal value to determine whether a flame is present; and a converter that converts the voltage signal provided by the flame monitoring device into a current signal. Such an electronic circuit is simple, reliable, and cost-effective. The electronic circuit converts the voltage signal into a current signal corresponding to the flame ionization current.

[0012] The gas burner appliance of the invention is defined in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Preferred developments of the invention are provided in the remainder of the specification and in the following description. Exemplary embodiments are explained in more detail based on the accompanying drawings, in which:

[0014] Figure 1 A schematic diagram showing a gas burner appliance with a flame monitoring device according to the present invention;

[0015] Figure 2 A block diagram of the electronic circuit of the flame monitoring device according to the present invention is shown. DETAILED DESCRIPTION

[0016] Figure 1 A schematic diagram of a gas burner appliance 10 is shown. The gas burner appliance 10 comprises a gas burner chamber 11 with a gas burner surface 13, in which combustion of a gas / air mixture having a certain mixture ratio of combustible gas G to air A occurs during a burner-on state of the gas burner appliance 10. The combustion of the gas / air mixture produces a flame 12.

[0017] By mixing the air flow with the gas flow, a gas / air mixture is provided to the burner chamber 11 of the gas burner appliance 10. A fan 14 draws in air A flowing through an air duct 15 and gas G flowing through a gas duct 16. A gas regulating valve 18 and a gas safety valve 19 for regulating the gas flow through the gas duct 16 are assigned to the gas duct 16.

[0018] The gas / air mixture having this gas-air mixing ratio is supplied to the burner chamber 11 of the gas burner device 10. The gas / air mixture is provided by mixing the air flow provided by the air duct 15 with the gas flow provided by the gas duct 16. The air flow and the gas flow are preferably mixed by a mixing device 21. Such a mixing device 21 can be designed as a so-called Venturi nozzle.

[0019] The amount of the air flow and thus of the gas / air mixture flow is regulated by the fan 14, ie by the speed of the fan 14. The fan speed can be regulated by an actuator 22 of the fan 14.

[0020] The fan speed of the fan 14 is controlled by a controller 20 which generates a control variable for an actuator 22 of the fan 14 .

[0021] The defined mixing ratio of the defined gas / air mixture is controlled by the gas regulating valve 18, ie by the pneumatic controller 17 of the gas regulating valve 18. The pneumatic controller 17 of the gas regulating valve 18 controls the open / closed position of the gas valve 18.

[0022] The position of the gas valve 18 is adjusted by the pneumatic controller 17 based on the pressure difference between the gas pressure of the gas flow in the gas pipe 16 and the reference pressure. The gas regulating valve 18 is controlled by the pneumatic controller 17 so that at the outlet of the gas valve 18, the pressure is equal to the reference pressure.

[0023] exist Figure 1 In the embodiment of the present invention, the ambient pressure is used as the reference pressure. However, it is also possible to use the air pressure of the air flow in the air duct 15 as the reference pressure. The pressure difference between the gas pressure and the reference pressure is pneumatically determined by the pneumatic sensor of the pneumatic controller 17.

[0024] Alternatively, it is possible to determine the pressure difference between the gas pressure of the gas flow in the gas pipe and a reference pressure electronically by an electrical sensor (not shown). In this case, the gas valve 18 will be controlled by an electronic controller (eg, controller 20).

[0025] In any case, the mixing ratio of the defined gas / air mixture is controlled such that the defined mixing ratio of the defined gas / air mixture remains constant over the entire modulation range of the gas burner appliance 10 .

[0026] A modulation of "1" means that the fan 14 operates at the maximum fan speed and thus at the full load of the gas burner. A modulation of "5" means that the fan 14 operates at 20% of the maximum fan speed, and a modulation of "10" means that the fan 14 operates at 10% of the maximum fan speed.

[0027] By varying the fan speed of the fan 14, the load of the gas burner appliance 10 can be adjusted. Across the entire modulation range of the gas burner appliance 10, a defined mixing ratio of the defined gas / air mixture remains constant.

[0028] As described above, the defined mixing ratio of the gas / air mixture is controlled during the burner-on state such that the defined mixing ratio of the gas / air mixture remains constant throughout the entire modulation range of the gas burner appliance 10 .

[0029] The controller 20 controls the operation of the gas burner appliance 10 based on signals provided by the flame monitoring device 23 .

[0030] The flame monitoring device 23 comprises a flame monitoring device 24 which provides a voltage signal EVS as a measurement signal depending on the presence of the flame 12. The flame monitoring device 24 is preferably provided by a thermocouple.

[0031] The flame monitoring device 23 further includes an electronic circuit 25 that converts the voltage signal EVS provided by the flame monitoring device 24 into a current signal ECS.

[0032] The flame monitoring device 24 of the flame monitoring device 23 provides a voltage signal EVS which is independent of the presence of ions in the flame 20. The electronic circuit 25 of the flame monitoring device 23 converts the voltage signal EVS into a current signal ECS which corresponds to the electrical flame ionization current.

[0033] The flame monitoring device 23 according to the present invention can provide a conversion kit for a gas burner appliance 10 having a flame ionization sensor and a controller 20 adapted to use the flame ionization current provided by the flame ionization sensor as an input signal, i.e., by replacing the flame ionization sensor with the flame monitoring device 23 and by retaining the controller 20. Thus, a gas burner appliance configured to combust methane as a combustible gas can be easily adapted to a gas burner appliance configured to combust hydrogen as a combustible gas without having to replace the controller 20.

[0034] The electronic circuit 25 of the flame monitoring device 23 includes a comparator 26. The comparator 26 compares the voltage signal EVS provided by the flame monitoring device 24 with the nominal value NVU to determine whether a flame 12 is present. The comparator 26 has a first input terminal 26a connected to the flame monitoring device 24, a second input terminal 26b at which the nominal value NVU is present, and an output terminal 26c.

[0035] When the voltage signal EVS is greater than the nominal value NVU, the presence of the flame 12 is detected and the voltage signal EVS is provided at the output terminal 26c.

[0036] When the voltage signal EVS is less than the nominal value NVU, the absence of the flame 12 is detected, and the voltage signal EVS is not provided at the output terminal 26 c.

[0037] The electronic circuit 25 of the flame monitoring device 23 further includes a converter 27 that converts the voltage signal EVS into a current signal ECS.

[0038] The converter 27 has an input terminal 27 a and an output terminal 27 b , and the input terminal 27 a is connected to the output terminal 26 c of the comparator 26 .

[0039] The converter 27 of the electronic circuit 25 of the flame monitoring device 23 comprises a second comparator 28 having a first input terminal 28 a , which provides an input terminal 27 a of the converter 27 , a second input terminal 28 b , and an output terminal 28 c .

[0040] The converter 27 of the electronic circuit 25 of the flame monitoring device 23 further comprises a first resistor 29 and a second resistor 30 connected in series between the output terminal 28 c of the second comparator 28 and the ground GND.

[0041] The second input terminal 28 b of the second comparator 28 and the output terminal 27 b of the converter 27 are both connected to a terminal 31 provided between the first resistor 29 and the second resistor 30 .

[0042] The present invention also provides a gas burner appliance 10. The gas burner appliance 10 includes a burner chamber 11 for burning a combustible gas, the combustion of which produces a flame 12. The gas burner appliance 10 includes a flame monitoring device 23 as described above and a controller 20 for controlling the operation of the gas burner appliance 10 based on a signal provided by the flame monitoring device 23.

[0043] The gas burner appliance 10 is configured to combust a combustible gas, wherein the combustion of the gas G produces an ion-free flame 12. The combustible gas G may contain hydrogen in an amount of up to 100%. The combustible gas G may be hydrogen.

[0044] Reference Signs List

[0045] 10 Gas burner appliances

[0046] 11 Gas burner chamber

[0047] 12 Flame

[0048] 13 Gas burner surface

[0049] 15 Air duct

[0050] 16 Gas pipelines

[0051] 17 Pneumatic controller

[0052] 18 Gas valve / regulating valve

[0053] 19 Gas valve / safety valve

[0054] 20 Controller

[0055] 21 Mixing device

[0056] 22 Actuator

[0057] 23 Flame monitoring device

[0058] 24 Flame monitoring device

[0059] 25 Electronic Circuits

[0060] 26 Comparator

[0061] 26a Input terminal

[0062] 26c input terminal

[0063] 26c output terminal

[0064] 27 Converter

[0065] 27a Input terminal

[0066] 27b output terminal

[0067] 28 Comparator

[0068] 28a Input terminal

[0069] 28b input terminal

[0070] 28c output terminal

[0071] 29 resistors

[0072] 30 resistors

[0073] 31 terminals.

Claims

1. A flame monitoring device (23) for a gas burner appliance, the gas burner appliance being configured to burn a combustible gas, the combustion of the combustible gas generating a flame (12), the flame monitoring device (23) for the gas burner appliance comprising: a flame monitoring device (24) which provides a voltage signal as a measurement signal depending on the presence of the flame; An electronic circuit (25) converts the voltage signal provided by the flame monitoring device (24) into a current signal, wherein the electronic circuit (25) comprises: a first comparator (26) that compares the voltage signal provided by the flame monitoring device (24) with a nominal value to determine whether a flame is present, wherein the first comparator (26) has: a first input terminal (26a) connected to the flame monitoring device (24); a second input terminal (26b) at which the nominal value is present; and an output terminal (26c); A converter (27) for converting a voltage signal provided by the flame monitoring device (24) into a current signal, wherein the converter (27) has an input terminal (27a) and an output terminal (27b), the input terminal (27a) being connected to the output terminal (26c) of the first comparator (26), and the converter (27) includes: a second comparator (28) having a first input terminal (28a), a second input terminal (28b), and an output terminal (28c), the first input terminal (28a) providing the input terminal (27a) of the converter (27); A first resistor (29) and a second resistor (30) are connected in series to an output terminal (28c) of the second comparator (28), wherein a second input terminal (28b) of the second comparator (28) and an output terminal (27b) of the converter (27) are both connected to a terminal (31) provided between the first resistor (29) and the second resistor (30).

2. The flame monitoring device according to claim 1, characterized in that: The current signal provided by the electronic circuit (25) corresponds to the flame ionization current.

3. The flame monitoring device according to claim 1, characterized in that: The flame monitoring device (24) is a thermocouple.

4. The flame monitoring device according to any one of claims 1 to 3, characterized in that: The flame monitoring device (10) provides a conversion kit for a gas burner appliance having a flame ionization sensor and a controller adapted to use the flame ionization current provided by the flame ionization sensor as an input signal, i.e. by replacing the flame ionization sensor with the flame monitoring device and by retaining the controller.

5. A gas burner appliance (10), comprising: a burner chamber (11) for burning a combustible gas, the combustion of the combustible gas generating a flame; The flame monitoring device (23) according to any one of claims 1 to 4; A controller (20) for controlling the operation of the gas burner appliance based on signals provided by the flame monitoring device (23).

6. The gas burner appliance according to claim 5, characterized in that The gas burner appliance is configured to combust a combustible gas, wherein the combustion of the gas produces a flame free of ions.

7. The gas burner appliance according to claim 5 or 6, characterized in that The gas burner appliance is configured to burn a combustible gas containing hydrogen in an amount of up to 100%.

8. The gas burner appliance according to claim 5 or 6, characterized in that The gas burner appliance is configured to combust hydrogen as the combustible gas.

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