EP4345377A1 - Device for a heating device, heating device and method for operating same - Google Patents

Abstract

A method for operating a heater (1) is proposed with the following steps: a) determining a fuel supply and an air supply for a predetermined power point of the heater (1); b) specifying operating parameters of a fuel fitting (3) and a conveyor device (5) for setting a corresponding volume flow in at least one fuel line (2) and at least one air line (4); c) supplying fuel and air to a fuel-air mixture line (6); d) temporarily reducing the volume flow of the fuel by means of an adjustable throttle valve (8) in the fuel line (2) during step c). Furthermore, devices or heaters are proposed with which this method can be carried out.

Description

The invention relates to a device for a heater, a heater and a method for operating it. In addition, a computer program product is also specified that can carry out the corresponding operation of the heater.

The invention relates in particular to a device for gas fittings in order to improve the ignition process of hydrogen-air or hydrogen-natural gas-air mixtures in gas-operated condensing boilers.

To start a gas burner, the safety valve in the fuel gas supply is usually opened. A quantity of gas corresponding to the required burner output is then added, adjusted to the air flow being supplied. Due to the valve size and the fixed flow resistances to the mixing point, the same mixing ratio of gas and air is always provided in known gas-air compound controls.

During the ignition phase, the combustible air-gas mixture reaches the burner of the heater, where it burns after the ignition energy has been introduced. However, it is possible that (at least sometimes) the combustible air-gas mixture is not ignited immediately, which can lead to an accumulation of the combustible air-gas mixture in the area of the burner. Delayed ignition, which refers to the ignition of the accumulated flammable air-gas mixture, can result in a deflagration, which can damage internal components of the heater and endanger the surrounding area. Delayed ignition can have particularly serious consequences for devices or environments that burn a flammable air-hydrogen mixture.

It is therefore the object of the invention to at least partially solve the problems described with reference to the prior art. In particular, a device for a heater and an adapted operating mode of a corresponding device are to be provided, which reduces the risk of corresponding serious consequences of a deflagration and/or enables quieter operation or start-up process of the heater. Simple and compact retrofitting of existing heating devices should also be possible.

This object is achieved with a device, a method, a heating device and a computer program according to the features of the independent patent claims. Further advantageous embodiments of the solution proposed here are specified in the dependent patent claims. It is pointed out that the features listed in the patent claims can be combined with one another in any technologically reasonable way and define further embodiments of the invention. In addition, the features specified in the patent claims are specified and explained in more detail in the description, with further preferred embodiments of the invention being presented.

A device for a heater contributes to this, wherein this device comprises at least one fuel line with at least one fuel fitting as well as at least one air line and at least one conveying device. The at least one fuel line and the at least one air line flow into one another and form (from there) a (common) fuel-air mixture line to a burner of the heater, via which the fuel-air mixture can be conveyed by means of the at least one conveying device. An adjustable throttle valve is provided in the fuel line, which cannot be closed completely.

The heating device is in particular a gas heating device that is designed to burn a fuel gas, such as natural gas or in particular hydrogen, with the addition of ambient air and to generate thermal energy, for example for heating a heat carrier of a heating circuit or for providing a hot water supply. In particular, the heating device can be designed as a gas-operated condensing heating device, which is designed in particular for burning (gaseous) fuel comprising hydrogen or a natural gas containing hydrogen.

The provision of fuel and air to the device can initially take place separately (via at least one fuel line and at least one air line), with the respective volume flows being adjustable by means of the fuel fitting on the one hand and the conveying device on the other, in particular with regard to the desired mixture ratios during combustion (combustion air ratio , also known as air ratio or lambda).

The heater generally has a burner with a combustion chamber surrounding it and a conveyor or fan that can convey a mixture of fuel and combustion air via a fuel-air mixture line into a combustion chamber in which a burner is arranged. The combustion products can then be fed to the heater for cleaning through an exhaust line.

The burner itself can include at least one perforated plate that is connected to a burner cavity. The burner cavity is connected to the fuel-air mixture line so that the fuel-air mixture can flow via the cavity through the perforated plate and be burned. An ignition device can also be arranged in the area of the perforated plate and is designed to ignite a mass flow of the fuel-air mixture emerging through the perforated plate. The burner cavity, also referred to as the burner body, can be used in particular as a cylinder (straight circular cylinder). be designed, wherein a base area of the cylinder is connected to the fuel-air mixture line and the opposite base area can be closed. Alternatively, the burner cavity can also be cuboid-shaped, which is delimited at the top by the perforated plate.

The heater may have a flame monitor that can detect the presence and/or quality of a flame on the burner and, if the flame goes out, interrupt the fuel supply. A signal from the flame monitoring can be used to regulate and control the heater, in particular to determine and regulate a combustion air ratio of the fuel-air mixture. The flame monitoring may include a sensor for detecting UV (ultraviolet) radiation emitted by the flame, an ionization electrode for detecting an ionization current of the flame and/or at least one temperature sensor for detecting a flame temperature.

In addition to the fuel fitting, which usually adjusts the desired fuel to match the air flow and in accordance with the specifically desired combustion air ratio, the fuel line also has an adjustable throttle valve that cannot be completely closed. This throttle valve can be operated, for example, via a coil drive or another switchable drive, such as a stepper motor. The throttle valve is designed in such a way that when open it allows practically the entire amount of gas provided by the fuel fitting to pass through and when closed (throttle) it limits the gas flow to a smaller value, which is significantly greater than 0%.

It is possible for the throttle valve to be (completely or almost completely) open in the inactive, in particular de-energized, state and to produce a reduced flow cross section in the active, in particular energized, state. Alternatively, it is possible for the throttle valve to be in the inactive, especially de-energized, state is completely open and produces a reduced flow cross section in the active, especially de-energized, state. It is particularly preferred that the adjustable throttle valve in the active state is closed to a maximum of 50%, in particular in the range from 60% to 80% (based on the maximum cross section that can be freely flowed through).

The adjustable throttle valve can be provided between the fuel fitting and a discharge point of the fuel-air mixture line. In the direction of flow of the fuel, this is first precisely metered through the fuel fitting with a view to the desired combustion air ratio and then throttled before it reaches the fuel-air mixture line. The adjustable throttle valve is preferably arranged in a section of the fuel line that runs from the fuel fitting to the discharge point.

It is possible that a safety valve for closing and releasing the fuel line is also provided upstream of the fuel fitting and adjustable throttle valve. The safety valve is designed in particular so that it can (completely) release or (completely) stop the fuel supply to the fuel fitting. The safety valve can be controlled as required, e.g. opened when the heater is started and/or closed in the event of a fault or when the heater is switched off. A single (double-acting) safety valve or two safety valves, a single burner fitting and a single adjustable throttle valve can be provided in the fuel line and in this order.

The device can further comprise a control device, designed to operate at least the fuel valve, the conveyor device and the adjustable throttle valve. Preferably, the control device is connected to the respective actuators or servo drives via a signal line. The control device can automatically control the operation of the fuel valve, the Check and determine the conveying device and the adjustable throttle valve. The regulating and control device can be set up in particular to carry out the process explained here.

According to a further aspect, a heater is proposed, comprising a device presented here and a burner with an ignition device, with a regulating and control device being provided, set up to operate at least the fuel fitting, the conveying device, the adjustable throttle valve and the ignition device. The burner or the ignition device can also include flame monitoring. This also enables controlled operation of the burner or operation of the fuel fitting, the conveying device and the adjustable throttle valve that is tailored to the combustion.

1. a) Bestimmen einer Brennstoffzufuhr und einer Luftzufuhr für einen vorgegebenen Leistungspunkt des Heizgerätes;
2. b) Festlegen von Betriebsparametern einer Brennstoffarmatur und einer Fördereinrichtung zur Einstellung eines entsprechenden Volumenstroms in mindestens einer Brennstoffleitung und mindestens einer Luftleitung;
3. c) Zuführen von Brennstoff und Luft hin zu einer Brennstoff-Luft-Gemischleitung;
4. d) Zeitweises Reduzieren des Volumenstroms des Brennstoffs mittels eines einstellbaren Drosselventils in der Brennstoffleitung während Schritt c).

What is proposed here is a method for operating a heater that includes at least the following steps:

1. a) determining a fuel supply and an air supply for a given power point of the heater;
2. b) determining operating parameters of a fuel fitting and a conveyor device for setting a corresponding volume flow in at least one fuel line and at least one air line;
3. c) supplying fuel and air to a fuel-air mixture line;
4. d) Temporarily reducing the volume flow of the fuel by means of an adjustable throttle valve in the fuel line during step c).

For the structural features of the heater and its components, reference can be made in full to the explanations elsewhere in this description, also in connection with the figure.

Steps a), b), c) and d) can be carried out at least once in the specified order. In particular, steps a) and b) can be carried out in parallel or at the same time. In addition, the method can be initiated when (re)starting the heater or an (imminent) ignition process.

The method and/or the device described should or can ensure that a reduced amount of fuel is provided during the starting/ignition process and that the amount of fuel required for the burner output is then mixed in during regular operation.

In step a), a fuel supply and an air supply are determined for a given performance point of the heater. The performance point of the heater can be predetermined by its function (hot water provision, etc.). The performance point can be a predetermined (stored or fixed) reference point or a point determined based on current ambient conditions or settings of the heating system. Operating parameters are specified for this performance point (or the corresponding combustion air ratio) that define the required amount (mass flow or volume flow) of fuel supply and air supply so that the desired performance is achieved.

Based on this, according to step b), operating parameters of a fuel fitting and a conveyor device for setting a corresponding volume flow in at least one fuel line and at least one air line are determined. It is possible that in particular the motors, actuators, etc. of the fuel fitting and conveyor device are controlled in such a way that the required volume flows are set specifically or exactly.

At the same time or afterwards, the (controlled) supply of fuel and air to a fuel-air mixture line can take place, see step c). This means that fuel and air now flow in the corresponding lines.

According to step d), the volume flow of the fuel is temporarily reduced or throttled by means of an adjustable throttle valve in the fuel line. It is possible for the adjustable throttle valve to be activated in parallel to the previous steps or at least at the beginning of step c), i.e. in particular to set the reduced flow cross section. This throttle valve is activated or operated, for example, via a coil drive or other drive, such as a stepper motor. It is preferred that the adjustable throttle valve has two specific states (active/inactive), which can be switched selectively. In particular, it is provided that the throttle valve is activated at the beginning of step d) and then switched to inactive at the end of step d). In particular, it is possible for the reduction during step d) to be constant, possibly also essentially independent of the actual power point of the heater.

It is possible that step d) is carried out with the initiation of step c). This means in particular that the reduction or throttling is already active (immediately) when the fuel flow begins.

Step d) can be ended again after a predetermined period of time. The time period can be, for example, in the range of 1 to 5 seconds, although a time period of 2 to 3 seconds can be advantageous when hydrogen is used as fuel.

It is possible for step d) to only be completed when at least one predetermined status parameter of the heater or a water circuit connected to it reaches a target value. The status parameters of the heater include, for example, the safety time of the ignition device, the temperature in the combustion chamber of the burner, etc The result of the evaluation of the flame monitoring is taken into account. A status parameter of the water circuit connected to it can in particular be at least one (water) temperature in the heating circuit and/or its change over time.

Furthermore, a heater is proposed with a fuel fitting, a delivery device, an adjustable throttle valve and means which are adapted to carry out the steps of the method specified here. The means can in particular include an appropriately set up control and control device.

A further aspect relates to a computer program comprising instructions that cause the heating device disclosed here to carry out the specified method steps. A computer-readable medium can be provided on which this computer program is stored.

The statements relating to the device, the heater, the method and the computer program can be used in their entirety to characterize the other aspect mentioned above.

The invention and the technical environment are explained in more detail below using the accompanying figure. It should be noted that the invention is not intended to be limited by the exemplary embodiment given. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figure and combine them with other components and findings from the present description. In particular, it should be noted that the figure and in particular the proportions shown are only schematic.

Fig.1 shows a device for a heater 1, which comprises a fuel line 2 with a fuel fitting 3 and an air line 4. The fuel line 2 opens into the air line 4 at a so-called outlet point 9. From there, a common fuel-air mixture line 6 extends to a burner 7 of the heater 1. A conveying device 5, here designed as a fan, for example, is also provided, with which the fuel-air mixture can be conveyed. It is of course possible to provide the conveying device in the air line 4. It is also possible for the air line 4 (or the conveying device 5 if it is positioned in front of the outlet point 9) to be assigned an air mass flow sensor 17, via which the current mass flow of air can be determined directly or indirectly (derived).

The following components are arranged in the fuel line 2 in the direction of flow towards the mouth point 9: a safety valve 10, a fuel fitting 3 and an adjustable throttle valve 8, the latter of which cannot be completely closed. These components can be used to adjust whether and with what quantity fuel is mixed into the air.

The predefined fuel-air mixture is fed to a burner 7, in whose surrounding burner chamber the flames are formed and where an ignition device 12 and a burner temperature sensor 18 are also provided. The ignition device is provided and set up to ignite the incoming fuel-air mixture. The burner temperature sensor 18 can be part of a flame monitoring system and can be used to evaluate the presence and/or quality of the flames.

The burner 7 is set up to influence an adjacent water circuit 13 in a heat-conducting manner. In particular, the water circuit 13 can lead a liquid heat transfer medium (water) past the burner so that it absorbs and dissipates the heat. To describe the status of the water circuit 13, a flow temperature sensor 14 can record the temperature when the heat transfer medium flows in Temperature sensor return, the temperature when the heat transfer medium flows away and / or a flow sensor 16 is used or used to determine the flow rate of heat transfer medium.

The fuel-air mixture burned in the burner 7 can be cleaned via an exhaust pipe 20.

Furthermore, a (central) control device 11 is provided, which is connected to the components mentioned via a plurality of signal lines 19 and can thus monitor and/or adjust their operation. In particular, the control device is set up to carry out the method proposed here.

A possible operation is explained below using the structure of the heater as an example.

If the burner 7 is to be started, the safety valve 10 is opened by the control unit 11 and the fuel fitting 3 (control valve) goes into the position that allows the amount of fuel required for the load point of the burner 7 to pass through.

The adjustable throttle valve 8 is actuated by the control unit 11, e.g. via a coil drive. The adjustable throttle valve 8 is now set so that in the active, i.e. partially closed (throttled), state the flow of fuel is limited to preferably 60-80%.

When the safety valve 10 is opened, the ignition device 12 (eg spark or glow igniter) is also started and the so-called safety time begins. This can be in the range between 1 and 5 seconds, preferably 2 to 2.5 seconds for hydrogen burners. After the safety time has expired, the adjustable throttle valve 8 becomes inactive switched, i.e. completely opened again, so that the regular amount of fuel is made available to the burner 7.

In addition, the switchover can also occur if the (water) temperature in the heating circuit increases (e.g. by min 1 K) and/or the temperature in the combustion chamber reaches a limit value and/or an evaluation of the glow plug signal or the flame monitoring shows that the flame is properly formed.

With the described device and the method it can be ensured that a reduced amount of gas is provided during the starting/ignition process and that the amount of gas required for the burner output is then mixed in during regular operation.

Reference symbol list

1

heater

2

Fuel line

3

Fuel valve

4

Air line

5

Grant submission

6

Fuel-air mixture line

7

burner

8th

adjustable throttle valve

9

Mouth point

10

Safety valve

11

Control and regulation device

12

Ignition device

13

Water cycle

14

Temperature sensor flow

15

Return temperature sensor

16

Flow sensor

17

Mass air flow sensor

18

Burner temperature sensor

19

Signal line

20

Exhaust pipe

Claims (12)

Device for a heater (1), at least comprising at least one fuel line (2) with at least one fuel fitting (3) as well as at least one air line (4) and at least one conveying device (5), wherein the at least one fuel line (2) and the at least one air line (4) open into one another and form a fuel-air mixture line (6) to a burner (7) of the heater (1), via which fuel-air mixture can be conveyed by means of the at least one conveying device (5), characterized in that an adjustable throttle valve (8) which cannot be completely closed is provided in the fuel line (2). Device according to claim 1, characterized in that the adjustable throttle valve (8) is closed to a maximum of 50% in the active state and open in the inactive state. Device according to claim 1 or 2, characterized in that the adjustable throttle valve (8) is provided between the fuel fitting (3) and an outlet point (9) of the fuel-air mixture line (6). Device according to one of the preceding claims, characterized in that a safety valve (10) for closing and releasing the fuel line (2) is additionally provided upstream of the fuel fitting (3) and the adjustable throttle valve (8). Device according to one of the preceding claims, characterized in that it comprises a regulating and control device (11) configured to operate at least the fuel valve (3), the conveying device (5) and the adjustable throttle valve (8). Heating device (1) comprising a device according to one of the preceding claims, characterized in that it has a burner (7) with an ignition device (12), wherein a regulating and control device (11) is provided, configured to operate at least the fuel fitting (3), the conveying device (5), the adjustable throttle valve (8) and the ignition device (12). Method for operating a heating device (1), characterized by at least the following steps: a) determining a fuel supply and an air supply for a predetermined power point of the heater (1); b) determining operating parameters of a fuel valve (3) and a conveying device (5) for setting a corresponding volume flow in at least one fuel line (2) and at least one air line (4); c) supplying fuel and air to a fuel-air mixture line (6); d) temporarily reducing the volume flow of the fuel by means of an adjustable throttle valve (8) in the fuel line (2) during step c). Method according to claim 7, characterized in that step d) is carried out with the initiation of step c). Method according to claim 7 or 8, characterized in that step d) is terminated after a predetermined period of time. Method according to one of claims 7 to 9, characterized in that step d) is only ended when at least one predetermined status parameter of the heater (1) or a water circuit (13) connected to it reaches a target value. Heater (1) comprising a fuel fitting (3), a conveyor (5), an adjustable throttle valve (8) and means adapted to carry out the steps of the method according to any one of claims 7 to 10. Computer program comprising instructions which cause the heating device (1) of claim 11 to carry out the method steps of any one of claims 7 to 10.

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