Procedure for commissioning a heating appliance, heating appliance and computer program

Abstract

A heating appliance (1) is proposed, comprising a conveying device (2) for conveying combustion air to a burner (3), a Venturi device (15) arranged downstream of the conveying device (2), and a gas valve (5) connected to a gas supply (8). A control line (17) is connected downstream of the Venturi device (15) to the gas valve (5) with respect to a flow direction (16) of the heating appliance (1), and the gas valve (5) is configured to adjust the fuel gas flow rate to the reference pressure of the control line (17). The heating appliance (1) enables an extended modulation range, in particular allowing the operation of the heating appliance (1) at high power levels. Furthermore, a method for commissioning the heating appliance and a computer program are described.

Description

[0001] The invention relates to a method for commissioning a heating device, a heating device and a computer program.

[0002] Heating appliances for the combustion of a fuel gas, such as natural gas or hydrogen, generally produce a combustion mixture of fuel gas and combustion air with a predetermined air-fuel ratio (also known as lambda or air-fuel ratio) and supply this mixture to a burner for combustion. Such heating appliances are also called premix burners. Various methods are known for determining the air-fuel ratio. Heating appliances with a pneumatic gas-air system detect a reference pressure, which is measured by a delivery device located in the vicinity of a throttling point, often called a Venturi, in the combustion air supply. This reference pressure allows for the calculation of the supplied mass flow of combustion air. Based on the reference pressure, the gas valve adds a mass flow of fuel gas corresponding to a predetermined air-fuel ratio. Such a heating appliance is described, for example, in EP 3 957 910 A1.Advantageously, pneumatic mixture formation does not require complex sensors and is therefore very robust in application and simple in design.

[0003] Commissioning of such a heating device typically involves starting up the delivery system to a predetermined initial output. Once this initial output is reached, and if necessary after a purge period designed to flush unburned fuel gas from the combustion chamber, the gas valve can be opened and a fuel gas flow rate corresponding to the initial delivery rate can be added. An ignition device can then be activated. If a flame sensor fails to detect a flame after a safety period, the commissioning attempt is aborted.

[0004] It has been shown that such heating appliances are sensitive to variations in the gas supply pressure. Aged ignition electrodes and / or gas valves can also contribute to a heating appliance producing clearly audible noises during startup or ignition, and a resulting harsh ignition can even damage the appliance. For example, an insufficient amount of fuel gas or an old ignition electrode can prevent the mixture in the combustion chamber from igniting, necessitating a restart, which is often accompanied by a clearly audible noise. One solution is to replace the gas valve and ignition electrode during a repair. This is very complex and expensive, and the costs may not be justified for an older heating appliance.

[0005] Based on this, the object of the invention is to propose a method for commissioning a heating device and a heating device that at least partially overcomes the problems of the prior art described above. In particular, noise during commissioning should be prevented.

[0006] Furthermore, the invention should not significantly increase the complexity of a heating device and should require only minor or, in particular, no structural changes to the heating device.

[0007] These problems are solved by the features of the independent claims. Further advantageous embodiments of the solution proposed here are specified in the independent claims. It should be noted that the features listed in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0008] This involves a method for commissioning a heating appliance. The heating appliance has a conveying device for supplying combustion air to a burner. Furthermore, a Venturi device is provided, which, with respect to the flow direction through the heating appliance, is arranged downstream of the conveying device. Additionally, a gas valve is provided, which is configured to add a mass flow of fuel gas to the combustion air supplied by the conveying device. The heating appliance also has a flame detector and an ignition device. During (initial or repeated) commissioning, the heating appliance starts up to a predetermined initial power output of the conveying device, whereby at least the following steps are performed: a) Detecting an ignition period, which extends from the opening of the gas valve until a flame is detected by the flame detector (so-called ignition process), b) Comparing the ignition period recorded in step a) with a previously mentioned reference period, and c) Adjusting the initial output of the conveying device if a deviation identified in step b) as part of the comparison reaches or exceeds a predetermined value.

[0009] Steps a), b), and c) can be performed at least once in the specified order during a regular operating procedure. In particular, steps a), b), and c) can be performed each time the heating appliance is started up. This procedure serves primarily to ensure the safe start-up of the heating appliance and to prevent the generation of noises that impair comfort. Start-up refers specifically to the ignition process of the heating appliance. It is possible that the procedure proposed here is performed for the first time and / or after a predetermined operating period (time period, number of start-ups, etc.), possibly even only upon specific (manual) initiation.

[0010] The heating appliance is a gas-fired heating appliance comprising a conveying device, in particular a blower, capable of conveying a mass flow (or volume flow) of combustion air. The combustion air can be supplied via a combustion air inlet. A gas valve is configured to add a mass flow of fuel gas at a mixing point, corresponding to a predetermined combustion air ratio and the combustion air mass flow. This mixing point is located downstream of the conveying device, relative to the flow direction through the heating appliance. The resulting combustion mixture can then be fed via a mixture channel to a burner within the heating appliance and combusted there. The heating appliance also includes a flame detector, also known as a flame monitor, which can detect the presence of a flame.The flame detector can, for example, be an ionization electrode that detects an ionization current from the flame and thus confirms its presence. However, reliably detecting an ionization current is not possible with hydrogen-powered heating appliances, as hydrogen does not release a sufficient number of charge carriers during combustion. Therefore, other sensors are used to monitor a hydrogen flame, such as optical sensors (UV sensors) or temperature sensors. The heating appliance also has an ignition device at the burner, designed to ignite the combustion mixture exiting the burner. This ignition device can, for example, be an ignition electrode.

[0011] The heating appliance can, in particular, have a pneumatic gas-air system in which a Venturi device (Venturi nozzle) can be arranged as a throttling point downstream of the delivery device. A reference pressure (control pressure), which allows conclusions to be drawn about the effectively delivered mass flow of combustion air, is transmitted to the gas valve in a suitable manner. Alternatively, the heating appliance can have an electronic gas-air system in which the opening width of the gas valve is adjusted by means of an (adjustable) actuator according to an operating point and a combustion air ratio specified for that point. For this purpose, an operating point of the heating appliance is generally determined by measuring the supplied mass flow of combustion air, and a corresponding mass flow of fuel gas is added via the gas valve actuator.

[0012] The gas valve can reduce the pressure of the fuel gas from the pressure in the gas supply (e.g., pressure of the gas network) to the reference pressure.

[0013] The gas valve can add a mass flow of fuel gas corresponding to the differential pressure between the pressure of the control line and the pressure of the gas supply, and a predetermined combustion air ratio, thereby setting a predetermined combustion air ratio. The heating appliance can, in particular, be a wall-mounted condensing boiler.

[0014] The terms "upstream" and "downstream" refer to the direction of flow through the heating appliance from a combustion air supply to the exhaust system and thus to the direction of delivery of the conveying device.

[0015] Such a heating appliance can adjust its heating output to the heat demand, a process also known as modulation. This can occur within a modulation range specified for the appliance. To avoid frequent, wear-inducing switching on and off of the burner, modern heating appliances can operate within a wide modulation range, for example, 1:5 from 4.8 kW [kilowatts] to 24 kW. In the future, modulation ranges of 1:7 (for example, 3.4 kW to 24 kW) or even 1:10 (2.4 kW to 24 kW) are expected to be achieved.

[0016] The Venturi device (Venturi nozzle) can have a flow cross-section (diameter) that allows the heater to operate within a wide modulation range, for example, with a maximum to minimum power ratio of 4 or more. For instance, the modulation range can cover a range from a minimum power of 1 kW to 5 kW up to a maximum power of between 12 and 65 kW.

[0017] The mixing point, where fuel gas and combustion air are combined, can be located in the area of ​​the Venturi device. For example, a gas line can lead from the gas valve to the Venturi device. The mixing point can be located, in particular, in the area of ​​the throttling point of the Venturi device.

[0018] During the commissioning of such a heating appliance, the delivery system is first ramped up to a predetermined starting power. This ramp-up process primarily involves starting a circulation pump in a heating circuit connected to the appliance. Upon reaching the starting power, a predetermined starting speed of a delivery system designed as a blower may be activated. At or after reaching the starting power, a delay period may be observed to allow any remaining fuel gas from a previous ignition event in the combustion chamber to dissipate. Once the starting power is reached, the gas valve can be opened, adding combustion air and a mass flow of fuel gas corresponding to a predetermined air-fuel ratio (lambda) to the delivered flow. Simultaneously, the ignition system can be activated.The ignition period begins when the gas valve is opened or the ignition device is activated, and lasts until a flame is detected by the flame detector.

[0019] The invention is based in particular on the idea of ​​recording the actual ignition period during commissioning and drawing conclusions about determinable characteristics of the ignition process. For example, a very long ignition period suggests that an insufficient amount of fuel gas was supplied to the combustion chamber.

[0020] Thus, in step a), the ignition period is first recorded, from the opening of the gas valve until a flame is detected by the flame sensor during an ignition process. The ignition period can be determined by measuring the time from the opening of the gas valve until the flame sensor detects the presence of a flame. The recorded ignition period can, for example, be stored in the data memory of a process-executing control unit.

[0021] According to step b), the ignition period recorded in step a) can now be compared with a predefined reference period. This comparison can, in particular, include determining any deviation of the ignition period recorded in step a) from the predefined reference period. The reference period can be determined beforehand through tests on a reference heater. The reference period is characteristic of a regular ignition process during which no noise occurs or is generated.

[0022] According to step c), the starting power of the delivery device can be adjusted if the deviation determined in step b) during the comparison exceeds a predetermined value. Typically, the ignition period of a heating appliance will lengthen due to aging of the gas valve or ignition electrode, and the starting power will be adjusted according to step c) if the ignition period recorded in step a) is extended by the predetermined value compared to the reference period. In this case, the adjustment of the starting power would consist of increasing the amount of fuel gas in the combustion chamber during the ignition process. The starting power can be adjusted, in particular, to ensure that the amount of gas present in the combustion chamber after the reference period corresponds to a predetermined optimal amount of gas for the ignition process. The predetermined value can define a tolerance.For example, the specified value can be in a range of 5 percent to 15 percent of the reference period, particularly at 10 percent.

[0023] According to one embodiment of the invention, the change in starting power resulting from the adjustment in step c) and the resulting change in the ignition period can also be recorded and stored, so that this data is available or can be included in subsequent iterations of the method. This inclusion of previous data from earlier ignition processes can increase the precision of setting the ignition period and thus the amount of gas available for ignition in the combustion chamber after the reference period has elapsed.

[0024] However, an excessively short ignition period can also be detected using the method proposed here. In this case, the adjustment could consist of reducing the starting power of the conveying system.

[0025] According to a further aspect of the invention, a heating appliance is proposed. This appliance comprises a conveying device for supplying combustion air to a burner, a Venturi device arranged downstream of the conveying device with respect to the flow direction through the heating appliance, and a gas valve configured to add fuel gas to the supplied combustion air, as well as a flame detector, an ignition device, and a control unit. The heating appliance, and in particular its control unit, is configured to carry out a method proposed herein.

[0026] Furthermore, the heating device includes a control unit, which may contain or have a processor. The processor can execute a procedure, such as the one described here, which is stored, for example, in the control unit's memory. Parameters and data necessary for carrying out the procedure may also be stored or already stored in the control unit's memory.

[0027] To prevent noisy ignition due to dynamic gas pressure drops or component aging (electrode, gas valve), a software function can automatically adjust the ignition setpoint by changing the fan speed according to the installation conditions and over time, to the theoretical ignition time Ti. For example, if the measured ignition time is found to be greater than 110% of the expected theoretical ignition time Ti, the ISP (Ignition Set Point) can be adjusted to increase the gas flow. Automatic ISP adjustment can occur after each ignition cycle to account for the current conditions at the heater's location. The ISP can be adjusted in increments of, for example, 2% until the expected ignition time is reached. Maximum and minimum ignition times can be predefined to reduce or prevent excessively high and / or low ISP and other potential risks (e.g., CO emissions).can be avoided.

[0028] In accordance with a further aspect of the invention, a computer program product is proposed, configured to carry out a method proposed herein. In other words, this relates in particular to a computer program (product) comprising instructions which, when the computer program is executed, cause a computer to carry out a method proposed herein.

[0029] This paper proposes a method for commissioning a heating appliance, a heating appliance itself, and a computer program that at least partially solves the problems described with reference to the state of the art. In particular, the method enables a consistently reliable ignition process for the heating appliance without the generation of unpleasant noises.

[0030] Furthermore, the invention can be implemented without any structural modifications to a heating device and is therefore also ideally suited for retrofitting existing heating devices as part of the implementation of software.

[0031] The invention and its technical context are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1: a heating device suggested here, Fig. 2: Parameter profiles of a regular ignition process, Fig. 3: Parameter profiles of an irregular ignition process, and Fig. 4: Parameter profiles when carrying out a procedure proposed here.

[0032] Fig. Figure 1 shows an exemplary and schematic representation of a proposed heating device 1. This device may have an air supply 4 for combustion air. A Venturi device 15 may be arranged in the air supply 4. Viewed in a flow direction 16 of the heating device 1, a conveying device 2, designed as a blower, may be arranged upstream of the Venturi device 15, which can convey a mass flow of combustion air. A gas valve 5 may, in the area of ​​the Venturi device 15, particularly within the Venturi device 15, add a mass flow of fuel gas from a gas supply 8 to the mass flow of combustion air conveyed by the conveying device 2. The mixture of fuel gas and combustion air can be fed to a burner 3 via a mixture channel 12, exit from the burner into a combustion chamber 17, and combusted there. An ignition device 18 and a flame sensor 19 are also arranged on the burner 3 in the combustion chamber 17.A heat exchanger 13 is arranged in the combustion chamber 17, which can transfer the heat generated during combustion to a heating circuit 14 with a flow 6 and a return 9.

[0033] Downstream of the burner 3, an exhaust pipe 10 can convey combustion products to an exhaust system 11. A control unit 7 of the heating appliance 1 can be electrically connected to at least the gas valve 5, the conveying device 2, the ignition device 18, and the flame sensor 19. The control unit 7 can be configured to carry out a procedure proposed here. For this purpose, a computer program 20 can be stored in a memory of the control unit 7, which causes the control unit 7 to execute the steps of a procedure proposed here.

[0034] Fig. Figure 2 shows exemplary and schematic parameter curves of the heating device 1 during a regular ignition process. Therefore, the heating device 1 in the diagrams may be... Fig. 2, for example, a new heating device 1. The upper diagram shows the course of the gas pressure P 26 over time T at the Venturi device 15. For this purpose, the gas pressure can be measured, for example, in the area of ​​the gas supply 8. In addition, the upper diagram shows a course 34 of the flame state FS over time T, where a first flame state 24 indicates that no flame is detected by the flame sensor 19, and a second flame state 25 indicates that a flame is detected by the flame sensor 19. The detection of a flame and thus the occurrence of the second flame state 25 takes place at a second time 22. The lower diagram of the Fig. Figure 3 shows the course 27 of the gas quantity Q over time T. The gas quantity Q denotes the amount of gas available in the combustion chamber 17 for the ignition process. At a first time point 21, the gas valve 5 opens, with the period from the first time point 21 to the second time point 22 defining the ignition period 23. The ignition period 23 according to Fig. 2 can also be understood as reference period 36, since the ignition process according to Fig. 2 is a regular ignition process.

[0035] The gas pressure P noticeably drops from an initial gas pressure 35 to a minimum gas pressure 33 at the first time point 21 when the gas valve 5 opens. At the second time point 22, an optimal gas quantity 28 (see gas quantity curve 27) has been established in the combustion chamber 17, and a successful and noiseless ignition process 29 can take place, which can be detected by the flame sensor 19 through the detection of a flame and thus the second flame state 25.

[0036] The Fig. Figure 3 shows the diagrams of the Fig. 2 for an irregular ignition process in which the gas pressure P after opening the gas valve at the first time 21 drops to a significantly lower minimum gas pressure 33 than in a process where Fig. 2 shown, regular ignition process. This results in the following: after the reference period of 36... Fig. 2. An initial gas quantity 31 is present in the combustion chamber 17, which is less than the optimal gas quantity 28, resulting in an unsuccessful ignition 30. Only after a subsequent increased second gas quantity 32, which is significantly larger than the optimal gas quantity 28, has been present in the combustion chamber, can a successful ignition 29 occur. However, this ignition is accompanied by noise due to the increased second gas quantity 32. The ignition period 23 is recognizable in the example of an irregular ignition process according to... Fig. 3 significantly increased.

[0037] Fig. Figure 4 shows the diagrams according to Fig. 2 and Fig. 3 for an ignition process after carrying out a procedure proposed here. For example, a procedure proposed here could be used for the regular ignition process according to Fig. 3 have been carried out.

[0038] According to step a), the ignition period 23 can be determined by the in Fig. The irregular ignition process shown in section 3 can be recorded.

[0039] According to step b), the ignition period 23 recorded in step a) can be compared with the reference period 36. This comparison reveals a deviation, namely that the ignition period 23 recorded in step a) is significantly longer than the reference period 36.

[0040] According to step c), the starting power of the heating device 1 can now be adjusted. Here, due to the ignition period 23 being longer than the reference period 36, the starting power is increased according to the deviation of the ignition period 23 recorded in step a).

[0041] In a subsequent in Fig. In the ignition process shown in Figure 4, the minimum gas pressure 33 is largely the same as the minimum gas pressure 35 of the irregular ignition process according to Fig. 3. However, increasing the starting power results in an increase in the amount of gas Q present after the reference period 36 has elapsed. This means that the ignition period 23 during the ignition process according to Fig. 4. With (in step c) the starting power adjusted in the procedure proposed here, the optimal gas quantity Q 28 is present in the combustion chamber 17 after the reference period 36 has elapsed, and a successful and silent ignition 29 occurs after the reference period 36 has elapsed. In this respect, by carrying out the procedure proposed here, the necessary ignition period 23 could be adjusted such that a regular, silent ignition occurs. Reference symbol list 1 heater 2 Support facility 3 burners 4 Air supply 5 Gas valve 6 preliminary run 7 Control and monitoring unit 8 Gas supply 9 Return 10 Exhaust pipe 11 Exhaust system 12 Mixture channel 13 heat exchangers 14 Heating circuit 15 Venturi device 16 Flow direction 17 Combustion chamber 18 Ignition device 19 flame guards 20 computer program product 21 Time of gas valve opening 22 Time of detection of flame 23 Ignition period 24 first flame state 25 second flame state 26 Gas pressure curve 27 Gas quantity profile 28 optimal gas quantity 29 successful ignitions 30 unsuccessful ignitions 31 first gas quantity 32 second gas quantity 33 minimum gas pressure 34 Flame state progression 35 first gas pressure 36 Reference period QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 3 957 910 A1

[0002]

Claims

[1] Method for commissioning a heating appliance (1) comprising a conveying device (2) for conveying combustion air to a burner (3), a Venturi device (15) which is arranged downstream of the conveying device (2) with respect to a flow direction (16) of the heating appliance (1), further a gas valve (5) which is configured to add fuel gas to a mass flow of the combustion air conveyed by the conveying device (2), as well as a flame monitor (19) and an ignition device (18), wherein the heating appliance (1) starts up to a predetermined starting power of the conveying device (2) during commissioning, comprising at least the following steps: a) Detecting an ignition period (23), from the opening of the gas valve (5) until a flame is detected by the flame detector (17), , b) Comparing the ignition period (23) recorded in step a) with a previously known reference period (36), and c) Adjusting the initial output of the conveying device (2) if a deviation identified in step b) as part of the comparison reaches or exceeds a predetermined value. [2] Heating appliance (1) comprising a conveying device (2) for conveying combustion air to a burner (3), a Venturi device (15) which is arranged downstream of the conveying device (2) with respect to a flow direction (16) of the heating appliance (1), further a gas valve (5) which is configured to add fuel gas to a mass flow of the combustion air conveyed by the conveying device (2), a flame detector (19) and an ignition device (18) as well as a control and regulating device (7) configured for carrying out a method according to claim 1. [3] Heating device (1) according to claim 2, wherein the conveying device (2) is a blower. [4] Heating device (1) according to claim 2 or 3, wherein the Venturi device (15) is configured to set a ratio of maximum to minimum power of the heating device (1) greater than 4. [5] Heating appliance (1) according to any one of the preceding claims 2-4, wherein the heating appliance (1) is a wall-mounted heating appliance (1). [6] Heating appliance (1) according to one of the preceding claims 2-5, wherein a gas line opens from the gas valve (5) in the area of ​​the Venturi device (15). [7] Computer program product (20) comprising commands that cause a heating device (1) according to any one of claims 2 to 6 to execute a method according to claim 1.

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