DE102019121973A1 - Heating device for a building - Google Patents

Abstract

The invention relates to a heating device (1) for a building, in which a fuel gas-air mixture flow (2) is fed into a combustion chamber (3) and ignited there, characterized in that the heating device (1) is used for burning a predominantly hydrogen containing Fuel gas is set up and that a catalyst material (4) is arranged in the heater (1) for igniting the fuel gas-air mixture.

Description

The invention relates to a heating device for a building, a method for monitoring the combustion in the heating device and the use of a catalyst material. In particular, the invention is used for igniting and monitoring hydrogen condensing boilers.

The usual energy source for condensing boilers is natural or liquid gas. Either an electric spark or a glow element is used to ignite the combustion process. Both measures provide the activation energy necessary to start the reaction. In addition to a device for igniting the flame, condensing boilers generally also have a unit for monitoring the flame in order to prevent an unburned gas-air mixture from flowing out. The gas types mentioned above contain hydrocarbons (CH4, C2H6, C3H8, ...) which contain ionized oxidation intermediates, especially CH radicals, during combustion. This effect is used when monitoring a flame, in that when an electric field is applied to the flame area, it is measured whether an ionization current to be expected is actually present.

The function groups “ignition” and “monitoring” can only partially be combined, if at all, in such natural or liquid gas condensing boilers, so that the frequent need for different functional units or increased integration effort results in comparatively high costs in the product. Furthermore, the electrodes placed in the combustion chamber are subject to high requirements in terms of geometric positioning.

In the case of fuel gases that contain hydrogen exclusively or in high proportions, no ionized carbon-based oxidation intermediates occur during combustion, so that the method for flame monitoring described in the prior art cannot be used.

It is therefore the object of the invention to provide a heating device and a method which are suitable for the ignition and monitoring of hydrogen-rich fuel gases and preferably reduce or even overcome the disadvantages of the prior art.

This object is achieved according to the features of claim 1 in that the heating device is set up to burn a fuel gas containing predominantly hydrogen and that a catalyst material is arranged in the heating device to ignite the fuel gas-air mixture.

Advantageous refinements result from the features of the dependent claims.

Contributing to this is a heating device for a building, in which a fuel gas-air mixture flow is fed into a combustion chamber and ignited there, the heating device being set up to burn a fuel gas containing predominantly hydrogen and a catalyst material to ignite the fuel gas-air mixture is arranged in the heater.

The heater is generally used to heat a building, such as a residential building, and / or in particular to heat a water supply system, such as a water circuit in the residential building. The heater is usually a gas heater. In other words, this relates in particular to a heater which is set up to burn one or more gases, possibly with the supply of ambient air from a building, in order to generate energy for heating, for example, water for use in an apartment.

For example, the heater can be a so-called gas condensing boiler. The heater generally has at least one burner (with a combustion chamber) and a delivery device such as a fan, which delivers a mixture of fuel (gas) and combustion air (through a mixture duct of the heater) to the burner. The exhaust gas resulting from the combustion can then be routed through an (internal) exhaust pipe of the heater to an exhaust system (of a house). One or more heaters are connected to this exhaust system.

In order to ignite the mixture, a catalyst material such as platinum is placed in the gas-air mixture flow in the heater described here. Due to its properties, the catalyst material should enable the necessary activation energy to start the reaction without additional thermal energy (or ignition sparks).

According to an advantageous embodiment, it is proposed that the heater is set up to burn a fuel gas consisting of at least 90% hydrogen. The heater is particularly preferably suitable for burning hydrogen with ambient air from the building. In this context, the heating device can advantageously be designed as a so-called hydrogen condensing device.

According to a further advantageous embodiment, it is proposed that the catalyst material is at least partially formed with platinum. In particular, if the fuel gas consists of at least 90% hydrogen, platinum is particularly preferred as the catalyst, since platinum, due to its properties, has the necessary activation energy to start the reaction of hydrogen and oxygen from the air without additional thermal energy (or ignition sparks) enables.

According to a further advantageous embodiment, it is proposed that the catalyst material be held in the interior of the combustion chamber. For example, the catalyst material can be held in the form of a rod or a wire in an interior of the combustion chamber.

Alternatively or cumulatively, it can be provided that the catalyst material forms part of an inner surface of the combustion chamber. In this context, the catalyst material can, for example, be applied to an inner wall of the combustion chamber or integrated into the inner wall.

For example, a catalyst surface, such as a platinum surface, can be completely or partially incorporated into the burner material or additionally positioned above the burner surface (e.g. as a rod). In this way, it can be ensured in a particularly advantageous manner, without further auxiliary devices, that the gas stream flowing out is also burned when the gas valve is opened.

According to a further advantageous embodiment, it is proposed that a temperature sensor for monitoring the combustion be formed in the area of the catalyst material. In particular, the temperature sensor is arranged and / or set up in such a way that it can be used for flame monitoring. In this context, the temperature sensor can in particular be arranged and / or set up in such a way that it can measure a temperature or a change in temperature of the catalyst material. Since the catalytic reaction is associated with heating of the catalytic converter, a conclusion about the combustion process can be drawn from the temperature or temperature change of the catalytic converter material, which is particularly advantageous for monitoring the combustion.

In other words, this can in particular also be described in such a way that, in order to monitor the combustion process, the part acting as a catalyst can be equipped with a temperature sensor which detects the heating of the catalyst associated with the catalytic reaction. This heating can then be reported back to a device control of the heater, for example. The temperature sensor can be embedded in or attached to the catalytic converter as an independent sensor.

According to a further advantageous embodiment, it is proposed that the temperature sensor be formed with the catalyst material. As an alternative to an independent sensor, the temperature-dependent electrical resistance of the catalyst material (e.g. platinum) itself can be used in a particularly advantageous manner in this context, in particular by means of R = U / I and by impressing a voltage (or a Current) and measuring the current (or voltage) to determine the temperature-dependent resistance and thus indirectly the temperature or temperature change of the catalyst material.

According to a particularly preferred embodiment, the catalyst material acting as an ignition catalyst is also designed as a measuring resistor. The use of a platinum measuring resistor is also particularly preferred in this context.

According to a further advantageous embodiment, it is proposed that the catalyst material be in the form of a wire which is preferably attached to a carrier layer. This can advantageously contribute to increasing the temperature sensitivity.

To increase the temperature sensitivity, the catalyst material can, for example, be designed as a thin wire and applied, for example, to a ceramic carrier layer, preferably in meandering structures. A strip-shaped carrier can preferably be used. In this context, the meandering structure can also be applied to the top and bottom of the carrier strip. Furthermore, both sides can be evaluated electrically independently of one another. In this way, a one-sided drift of the sensitivity can be recognized in an advantageous manner by comparing the two values and, if necessary, the system can be brought into a safe error state if the deviation between the two measured values exceeds a tolerance limit.

1. a) Erfassen mindestens einer Temperatur oder Temperaturänderung des Katalysatormaterials,
2. b) Vergleichen der erfassten Temperatur oder Temperaturänderung mit zumindest einem Referenzwert oder Erwartungswert,
3. c) Beeinflussen des Betriebs des Heizgeräts in Abhängigkeit des Vergleichs aus Schritt b).

According to a further aspect, a method for monitoring the combustion in a heating device described here is proposed, comprising at least the following steps:

1. a) detecting at least one temperature or temperature change of the catalyst material,
2. b) comparing the recorded temperature or temperature change with at least one reference value or expected value,
3. c) influencing the operation of the heater as a function of the comparison from step b).

For detecting the at least one temperature or temperature change of the catalyst material, an electrical resistance or a change in the electrical resistance of the catalyst material can preferably be measured.

For monitoring the combustion, a reference value or expected value, such as a reference resistance value, can be stored in a device control of the heater. This can, for example, be determined at the factory as a fixed value and stored in the controller or (new) recorded after a longer period of standstill of the heater and used as a (new) reference resistance. In this way, drift effects of the measuring chain that occur over the service life of the device can be compensated for in an advantageous manner.

Preferably, during operation (ie during ignition or combustion), in particular during the starting process of the heater, the change in the electrical resistance of the catalyst material compared to the reference value is recorded in advantageously short time intervals (for example of a maximum of one second) and further preferably with a Compared expected value of the resistance over time. This expected value can also include a steady-state value for permanent burner operation and can optionally also vary as a function of the modulation specification of the heater.

If the measured resistance values do not correspond to any expected or permissible (or outside a tolerance range) heating, the fuel gas supply is usually interrupted (in step c) and the system is switched off in particular in a locking manner. This advantageously ensures that malfunctions in normal operation, caused for example by aging / passivation of the catalytic surface OR the supply of fuel gases that cannot be converted by means of the catalytic converter, are detected and a safety shutdown is initiated.

If the heating derived from the measured values occurs too quickly compared to the expected values, it can be concluded, for example, that there is a change in the thermal mass of the material used as a temperature sensor and / or the reaction temperature of the flame is higher than the expected value.

If the burner operation has exceeded a duration representing steady-state operation, in particular with (quasi) unchanged modulation specifications, and the measured value deviates from the expected value by an amount outside a tolerance range, a correction specification for the gas-air ratio in the case of an over-stoichiometric air ratio can be made (in step c) be derived.

In this context, an excessively high steady-state measured temperature can indicate an air ratio that is too low compared to the expected value and / or a too low steady-state measured temperature may indicate an air ratio that is too high compared to the expected value. A detected deviation can be fed back (to the gas-air network) by means of a control signal. For example (in step c) if the air ratio is too low, the fan speed or power of the delivery device can be increased and / or the gas valve opening position or the fuel gas volume flow can be reduced and (vice versa) if the air ratio is too high, the fan speed or power of the delivery device can be reduced and / or the Gas valve opening position or the fuel gas volume flow can be increased.

According to a further aspect, the use of a catalyst material for igniting a fuel gas predominantly containing hydrogen and for monitoring the combustion of the fuel gas in a heater is proposed. In this context, the heating device can be a heating device described here.

The details, features and advantageous configurations discussed in connection with the heating device can correspondingly also occur in the method and / or use presented here, and vice versa. In this respect, reference is made in full to the statements made there for a more detailed characterization of the features.

The invention will now be explained in detail with reference to the figures.

• 1: beispielhaft und schematisch ein hier beschriebenes Heizgerät, und
• 2: beispielhaft und schematisch einen Ablauf eines hier beschriebenen Verfahrens.

They represent:

• 1 : by way of example and schematically a heater described here, and
• 2 : an example and schematic of a sequence of a method described here.

1 shows an example and schematically a heater described here 1 for a building in which a fuel gas-air mixture flow 2 into a combustion chamber 3 out and ignited there, the heater 1 is set up to burn a fuel gas containing predominantly hydrogen and that a catalyst material is used to ignite the fuel gas-air mixture 4th in the heater 1 is arranged. The heater is an example 1 provided and set up here for burning a fuel gas consisting of at least 90% hydrogen. The burned fuel gas-air mixture can be passed through an exhaust gas flow 7th from the combustion chamber 3 be discharged.

Furthermore is the catalyst material 4th here, for example, is at least partially formed with platinum. In addition, is the catalyst material 4th here, for example, inside the combustion chamber 3 held. Alternatively it can be provided, for example, that the catalyst material 4th part of an inner surface of the combustion chamber 3 forms.

In the area of the catalyst material 4th a temperature sensor for monitoring the combustion is formed here as an example. For this purpose, the temperature sensor is shown in the exemplary illustration 1 with the catalyst material 4th (self) educated. The catalyst material 4th for example in the form of a wire 5 be formed, for example, on a carrier layer 6th is attached. According to the example shown here, the ignition catalytic converter can thus function particularly advantageously at the same time as a platinum measuring resistor.

2 shows an example and schematically a sequence of a method described here. The method is used to monitor the combustion in a heater described here 1 . The one with the blocks 110 , 120 and 130 The sequence shown of steps a), b) and c) is exemplary and can thus be run through at least once in a regular operating sequence. In addition, steps a) to c) can also run at least partially in parallel or simultaneously.

In block 110 according to step a), at least one temperature or temperature change of the catalyst material is recorded 4th . In block 120 according to step b), the detected temperature or temperature change is compared with at least one reference value or expected value, in block 130 the operation of the heater is influenced in accordance with step c) 1 depending on the comparison from step b).

This also provides an example of the use of a catalyst material 4th for igniting a fuel gas containing predominantly hydrogen and for monitoring the combustion of the fuel gas in a heater 1 shown.

A heater, a method and a use are thus specified which are suitable for the ignition and monitoring of hydrogen-rich fuel gases and in particular reduce or even overcome the disadvantages of the prior art.

List of reference symbols

1

heater

2

Fuel gas-air mixture flow

3

Combustion chamber

4th

Catalyst material

5

wire

6

Carrier layer

7th

Exhaust gas flow

Claims (10)

Heating device (1) for a building, in which a fuel gas-air mixture flow (2) is fed into a combustion chamber (3) and ignited there, characterized in that the heating device (1) is set up to burn a fuel gas predominantly containing hydrogen and that a catalyst material (4) is arranged in the heater (1) to ignite the fuel gas-air mixture. Heater (1) Claim 1 , characterized in that the heater (1) is set up to burn a fuel gas consisting of at least 90% hydrogen. Heater (1) Claim 1 or 2 , characterized in that the catalyst material (4) is at least partially formed with platinum. Heater (1) after one of the Claims 1 to 3 , characterized in that the catalyst material (4) is held in the interior of the combustion chamber (3). Heater (1) after one of the Claims 1 to 3 , characterized in that the catalyst material (4) forms part of an inner surface of the combustion chamber (3). Heater (1) according to one of the preceding claims, characterized in that a temperature sensor for monitoring the combustion is formed in the area of the catalyst material (4). Heater (1) Claim 6 , characterized in that the temperature sensor is formed with the catalyst material (4). Heater (1) according to one of the preceding claims, characterized in that the catalyst material (4) is formed in the form of a wire (5) which is preferably fastened to a carrier layer (6). Method for monitoring the combustion in a heating device (1) according to one of the preceding claims, comprising at least the following steps: a) detecting at least one temperature or temperature change of the catalyst material (4), b) comparing the detected temperature or temperature change with at least one reference value or expected value, c) influencing the operation of the heater (1) as a function of the comparison from step b). Use of a catalyst material (4) for igniting a fuel gas containing predominantly hydrogen and for monitoring the combustion of the fuel gas in a heater (1).

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