DE202022103597U1 - Hydrogen heating unit - Google Patents

Abstract

Heating unit for generating heat from a combustible gas, the heating unit comprising a burner (1) for generating the heat and at least one heat exchanger (15, 18) for transferring the heat generated to a liquid transport medium, the burner (1) being operable with hydrogen gas is, characterized in that the burner (1) has the following components:
- a combustion chamber (2) for receiving an aqueous solution (W), above which a liquid-free combustion chamber (4) remains, in which a pilot flame that can be fed by a fuel can be ignited;
- an oxygen supply (5) into the combustion chamber (4);
- an electrolyzer (6) for water for producing hydrogen and oxygen from the aqueous solution (W), the fission products of which can be introduced into the aqueous solution (W) of the combustion chamber (2); so that the gas generated by electrolysis can rise through the aqueous solution (W) and burn together with supplied oxygen and the pilot flame in the combustion chamber (4) to generate heat, which can then be given off to the heat exchanger (15, 18).

Description

Introduction

The invention relates to the field of gas-operated heating units. In particular, the invention relates to a hydrogen-operated heating unit for generating heat for heating and domestic hot water.

State of the art and disadvantages

Heating units for generating heat from a combustible substance such as oil or gas are well known. In such units, a combustible substance is oxidized through a thermal reaction, and the process heat released is fed to a mostly liquid medium using a heat exchanger, which is then conveyed via pipes to the location where the heat is needed and is removed from the medium again.

The known solutions are mostly based on fossil fuels, or at least on fuels that produce harmful exhaust gases when oxidized. Aggregates are therefore also known which use fuels that can be used largely without residue or without producing harmful gases or vapors. An example of this is the use of hydrogen, which becomes water vapor in the exothermic reaction with oxygen, releasing a significant amount of heat.

As is known, molecular hydrogen (H ₂ ) can be obtained from water using electrolysis, which requires electrical energy. Solutions are known in which solar power, which is generated during the day using appropriate systems, is used for electrolysis; The hydrogen produced in this way is then temporarily stored under high pressure and burned if necessary. The problem with this solution is the high safety requirements for such a system, as well as the space required for the storage and the associated high costs.

Task of the invention and solution

The invention is therefore based on the object of providing a heating unit which avoids the disadvantages of the prior art.

Accordingly, the operation of the heating unit according to the invention should be residue-free and safe.

The task is solved by a heating unit according to claim 1. Advantageous embodiments can be found in the dependent subclaims, the following description and the figures.

Description

First there is a description of a heating unit according to the invention; This is followed by a description of how to use it.

The heating unit is used to generate heat from a combustible gas for the purpose of using it to supply, for example, an apartment, a house or an industrial building with heat, in particular for heating. The heating unit comprises at least one burner for generating the heat and at least one heat exchanger for transferring the heat generated to a liquid transport medium, such as in particular water, which is used to transport the heat away. The burner can be operated with hydrogen gas.

• - Eine Brennkammer zur Aufnahme einer wässrigen Lösung wie insbesondere Wasser, welches reines Wasser ist oder auch mit Zusatzstoffen versehen sein kann. Über der wässrigen Lösung verbleibt ein flüssigkeitsfreier Brennraum. In diesem ist eine von einem Brennstoff speisbare Pilotflamme entzündbar. Der Brennstoff ist mittels einer Energiequelle zur Pilotflamme entzündbar. Das Vorliegen der Pilotflamme ist wichtig, um die Explosionsgefahr zu vermeiden, wie noch weiter unten beschrieben wird. Die Energiequelle muss nur kurzzeitig in Betrieb sein, da die Pilotflamme nach dem Entzünden aufgrund des Kontakts mit dem Brennstoff selbsttätig weiterbrennt.
• - Eine Sauerstoff-Zufuhr in die Brennkammer. Der Sauerstoff wird für die nachfolgende Verbrennung des Wasserstoffes im Brennraum benötigt. Der Brennraum kann entsprechende Öffnungen aufweisen, durch welche Sauerstoff oder sauerstoffhaltiges Gas in ihn einleitbar sind. Die Öffnungen können nahe oberhalb der brennbaren Flüssigkeit, oder mittig im Brennraum, oder im Bereich nahe unterhalb seiner Decke angeordnet sein. Bevorzugt sind sie in etwa mittig im unteren Teil des Brennraums, mindestens ca. 10 cm über der Pilotflamme, angeordnet.
• - Einen mit Strom betreibbaren Elektrolyseur für Wasser zur Erzeugung von Wasserstoff und Sauerstoff aus der wässrigen Lösung, deren Spaltprodukte wie insbesondere der Wasserstoff in die wässrige Lösung der Brennkammer einleitbar sind.

The invention is characterized in that the at least one burner has the following components:

• - A combustion chamber for holding an aqueous solution such as, in particular, water, which is pure water or can also be provided with additives. A liquid-free combustion chamber remains above the aqueous solution. In this, a pilot flame that can be fed by a fuel can be ignited. The fuel is ignitable using an energy source to the pilot flame. The presence of the pilot flame is important to avoid the risk of explosion, as described below. The energy source only needs to be in operation for a short time, as the pilot flame continues to burn automatically after ignition due to contact with the fuel.
• - An oxygen supply into the combustion chamber. The oxygen is needed for the subsequent combustion of the hydrogen in the combustion chamber. The combustion chamber can have corresponding openings through which oxygen or oxygen-containing gas can be introduced into it. The openings can be arranged close above the flammable liquid, or in the middle of the combustion chamber, or in the area close to the ceiling. They are preferably arranged approximately centrally in the lower part of the combustion chamber, at least approx. 10 cm above the pilot flame.
• - An electrolyser for water that can be operated with electricity to produce hydrogen and oxygen from the aqueous solution, their cleavage products such as water in particular material can be introduced into the aqueous solution of the combustion chamber.

The gases generated by electrolysis can rise through the aqueous solution and possibly an overlying layer of flammable liquid and burn together with supplied oxygen and the pilot flame in the combustion chamber, generating heat. The heat can then be transferred to the heat exchanger and transported away using the liquid transport medium.

Due to the presence of the pilot flame, hydrogen gas entering the combustion chamber is also burned immediately; This means it cannot accumulate and explode uncontrollably when ignited.

The invention thus avoids the disadvantages known from the prior art.

A heating unit according to the invention works practically without residue due to the use of hydrogen gas, which burns together with oxygen to form water vapor. Since the hydrogen is only produced when needed by electrolysis and then immediately burned, it does not have to be collected and stored under pressure with the corresponding energy and construction effort, which keeps the heating unit according to the invention small and increases its operational safety. The pilot flame also effectively prevents uncontrolled ignition of accumulated gas in the combustion chamber.

Various embodiments of the invention are described in more detail below.

According to one embodiment, the fuel for the pilot flame is in the form of a combustible liquid or a combustible gas, which can be injected into the combustion chamber. The injection can preferably take place laterally and close to the surface of the aqueous solution. The pilot flame is provided by igniting the fuel.

According to another embodiment, the fuel for the pilot flame is in the form of a layer of flammable liquid floating on the aqueous solution. A layer of a flammable liquid such as ethanol can be placed on the aqueous solution, which floats as a layer on top of the aqueous solution due to its lower density. In this case there is a pilot flame, such as that which forms at the liquid-air interface in an ethanol fireplace.

According to one embodiment of the heating unit, the flammable liquid is an alcohol. This can be easily injected into the combustion chamber or combustion chamber. But other substances such as ethanol or denatured alcohol are also conceivable as flammable liquids.

According to a further embodiment, the energy source can be operated electrically and generates heat. In particular, a so-called glow plug comes into consideration here, as is known from diesel engines or electric cigarette lighters. The energy source can also be provided, for example, by an ignition spark or a plasma arc. Mechanical ignition, for example using a piezo crystal, is also possible.

According to a further and particularly preferred embodiment, the oxygen comes from the ambient air. In this way, the amount of oxygen gas required for combustion is avoided in other ways. The supply of ambient air can preferably be controlled. Furthermore, a filter can be provided to retain suspended matter, etc., which is undesirable during combustion.

As mentioned, the electrolyzer has the task of splitting the water contained in the aqueous solution. An advantageous structure provides that the electrolyzer has two acid-resistant and preferably thin-walled, nested and in particular concentric electrodes made of metal grids, tubes or sheets or comprising such components. Corrosion-resistant steel, such as so-called V2A or preferably at least V4A steel, is particularly suitable for the cathode, which is preferably located on the outside. The preferably internal anode consists or comprises in particular a tungsten electrode and can be surrounded by a sheet or grid made of titanium or a titanium alloy in order to increase the surface area. Tests have shown that such a combination of materials enables particularly productive and low-maintenance operation of the heating unit.

According to a further embodiment, the heating unit also includes a heat storage, particularly preferably a so-called latent heat storage (also referred to as a phase change or PCM storage). The storage works together with a flame tube connected downstream of the burner, which means that the flame tube should allow the best possible heat release into the heat storage. This can be done, for example, by installing the flame tube inside of heat storage possible; The interior of the flame tube is in turn flowed through by the hot gas that comes from the burner. This means that the heat from the burning gas can get into the heat storage without coming into direct contact with it. The heat storage can hold, for example, 200 l of the storage medium.

A latent heat storage offers the advantage of a particularly large heat storage capacity relative to its volume, since in addition to the mere thermal heating of its contents, it also uses the latent heat associated with the transition of the storage medium from the crystalline to the liquid state for storage.

In the event that a latent heat storage is present, the heating unit preferably also includes a device for specifically triggering crystallization of the storage medium contained in the latent heat storage, for example in the form of providing an electrical or electromagnetic pulse. With crystallization triggered on demand, a large amount of heat (e.g. 10 kWh or more) is released over a longer period of time (e.g. 60 minutes). This process can be used to cover demand peaks as well as when there is no cheap electricity available for electrolysis, but heat is still needed. Conversely, if cheap electricity is available, a “discharging” heat storage device can be “charged” as a precautionary measure, which increases economic efficiency.

According to another embodiment, the heating unit includes a demand-controlled, i.e. heat requirement-dependent, injection for the fuel. This means that the fuel is only replenished when the electrolyser is supposed to go into operation; This also increases operational safety because there is only a small amount of fuel in the combustion chamber.

It is also preferred that the electrolysis can be triggered in a temperature-controlled manner. For this purpose, a liquid and/or a gas temperature sensor can preferably be present. The liquid temperature sensor is preferably arranged in the burner near the boundary layer between liquid (aqueous solution or layer of flammable liquid) and measures the temperature prevailing there. The gas temperature sensor protrudes into the combustion chamber and measures the temperature there.

To ensure safe operation, tests have shown that the temperature in the liquid should be at least around 85°C and in the combustion chamber above it should be around 95°C or more before the electrolysis is started and hydrogen gas enters the combustion chamber , since only from this temperature onwards a stable, automatic combustion of the hydrogen gas together with oxygen occurs. Accordingly, it is particularly preferred to also have a control system which only starts the electrolyser when the above-mentioned target temperature(s) is reached.

The liquid(s) in the burner are preferably warmed up using the pilot flame, which in turn only has to be started when there is a heat requirement that can no longer be covered by the amount of heat remaining in the (then existing) heat storage.

According to another embodiment, the heating unit comprises a pressure compensation container for the storage medium located in the heat storage. Since liquid media expands when heated, this can lead to an increase in pressure in the heat storage, which can be reduced or avoided entirely using a pressure compensation tank.

Furthermore, the heating unit can also include a second heat exchanger. The first heat exchanger can then be, for example, a tubular heat exchanger that can be connected to the heating circuit of a house and is preferably connected to the flame tube, i.e. which surrounds it as directly as possible. In this way, the (exhaust) gas burning at high temperatures is efficiently cooled down. The second heat exchanger can, for example, be a plate heat exchanger or tubular heat exchanger that can be connected to the domestic hot water storage tank of a house and is preferably arranged in the storage medium of the latent heat storage tank. This is well suited to transmitting the lower temperatures (compared to the temperatures prevailing in the flame tube, which are significantly above 100 °C) as they are in the heat storage (e.g. 50 to 80 °C). Although the crystallization takes place at a temperature of, for example, 54°C, it is clear that the storage can continue to heat up due to the spatial proximity to the flame tube (the storage medium is then in liquid form).

The provision of two heat exchangers further improves the economic efficiency of the heating unit and its possible uses.

According to another embodiment, the heating unit comprises a condenser arranged downstream of the flame tube. This serves to collect the water vapor produced by condensation during combustion. Since the temperatures immediately after the combustion of the hydrogen-oxygen mixture are still significantly above the boiling point of water, It is advantageous to also use the heat present in the exhaust gas. The capacitor in question is used for this purpose. The heat absorbed there can be transported to the storage tank using a heat pump, for example.

The condenser can optionally be preceded by a heat buffer, by means of which the hot exhaust gas is cooled down slightly. This can, for example, consist of or include very heat-resistant ceramic sponge material, as is also known, for example, from vehicle catalytic converters. If the heat buffer is sized accordingly, the downstream capacitor does not heat up to more than 100°C, which is desirable because otherwise it would not lead to condensation of the water vapor.

According to a preferred embodiment, the heating unit also includes at least one Peltier element connected to the above-mentioned capacitor for converting the waste heat generated in the capacitor into electrical energy. This can then be temporarily stored, for example using an accumulator, and can be fed back to the electrolyser if necessary, which further increases economic efficiency.

In addition, a Stirling engine is installed between the condenser and the flame tube or, preferably, the optional heat buffer. This is operated using heat and converts mechanical energy into electrical energy, which increases economic efficiency.

Furthermore, the electrical energy required to operate the electrolyser, which can, for example, require a voltage of 12 - 24 V and a current of 10 A, can also be supplemented or even completely replaced by solar power, provided that the system producing the electricity is sufficiently sized (For direct operation, a power of e.g. 250 kWp is sufficient). If there is a power storage device, it can be charged with solar power even if solar power is available and later discharged by the electrolyzer if necessary; In this case, a larger or smaller solar system can also be useful.

According to one embodiment, the heating unit includes a condensate line for returning the condensed water from the condenser to the combustion chamber. This means that a cycle is created in which essentially the same water is always split, burned and condensed, before being fed back into the splitting process (“closed” system). The water consumption of such a heating unit is therefore negligible.

Optionally, such a heating unit includes a compensation tank provided for the (circulating) water, which is arranged between the condensate line and the combustion chamber, as well as an inlet for (occasionally necessary) refilling or replacing this aqueous solution, and/or for adding additives.

According to another embodiment, the heating unit according to the invention is constructed in an “open” manner, i.e. it continuously consumes water or an aqueous solution. This must then be refilled accordingly, preferably also using an expansion tank that opens into the combustion chamber. Such a heating unit is therefore constructed in a simpler manner. In particular, such an open system can advantageously also be installed in an existing fireplace, e.g. in the combustion chamber of a gas or oil heater, a fireplace (preferably provided with a water pocket) or another heater that uses fossil fuels.

According to a preferred embodiment, the aqueous solution that can be introduced into the electrolyzer comprises 10% ± 5% sodium hydroxide (NaOH). The advantage of adding NaOH is that it increases the conductivity of the aqueous solution, which in turn promotes electrolysis. Another additive that promotes the same effect is also possible.

It is also preferred that 90% ± 5% of the aqueous solution is so-called “revived water” which has been “activated” in a manner known in the art. Tests have shown that water pretreated in this way does not tip over and therefore practically does not need to be replaced, which increases economic efficiency.

• - Aufspalten von in einer wässrigen Lösung enthaltenem Wasser mittels eines in diese Lösung eingebetteten Elektrolyseurs in Wasserstoff und Sauerstoff;
• - Einleiten der Spaltgase wie insbesondere zumindest des abgespaltenen Wasserstoffs in eine Brennkammer, in welcher die wässrige Lösung, sowie ein zuoberst angeordneter flüssigkeitsfreier Brennraum enthalten sind;
• - Aufsteigen des Wasserstoffs und Sauerstoffs durch die Flüssigkeiten in den Brennraum;
• - Verbrennen des Wasserstoffs und Sauerstoffs zusammen mit zugeführtem Sauerstoff und einer aus einem Brennstoff gespeisten Pilotflamme;
• - direktes oder indirektes Abgeben der beim Verbrennen erzeugten Wärme an einen Wärmetauscher.

The use of the heating unit described above for generating heat from a combustible gas is described below. This includes the following steps:

• - Splitting water contained in an aqueous solution into hydrogen and oxygen using an electrolyzer embedded in this solution;
• - Introducing the fission gases, in particular at least the split-off hydrogen, into a combustion chamber in which the aqueous solution and a liquid-free combustion chamber arranged at the top are contained;
• - Hydrogen and oxygen rise through the liquids into the combustion chamber;
• - Burning the hydrogen and oxygen together with supplied oxygen and a pilot flame fed from a fuel;
• - direct or indirect transfer of the heat generated during combustion to a heat exchanger.

In other words, electrical energy is used to operate an electrolyzer located in an aqueous solution, which splits off hydrogen from the water in this solution; This rises through the solution together with the oxygen and contacts a flame in the combustion chamber, where it burns to form water vapor, the term “burning” implying the presence of oxygen; additional oxygen is supplied to improve combustion; The heat released can now be removed and used at a suitable location.

To avoid repetition, reference is made to the above explanations of the heating unit according to the invention.

For example, the pilot flame is fed by a flammable liquid or gas which is injected into the combustion chamber. This fuel burns immediately, so it does not precipitate into liquid form.

However, the pilot flame is preferably fed by a layer of a flammable liquid floating on the aqueous solution. It is clear that in this case the fission gases also rise through this layer and then reach the liquid-free combustion chamber.

Here too, to avoid repetition, reference is made to the explanations above.

The electrolysis and the introduction of the fission gases, such as in particular the hydrogen gas, into the combustion chamber preferably only take place when a minimum temperature is exceeded. This is preferably at least 85 ° C below the boundary layer between liquid and liquid-free combustion chamber, and 95 ° C above it (i.e. in the combustion chamber). It is particularly preferred that the electrolyzer is only switched on when these temperature(s) are reached, which is detected using suitable temperature sensors and triggered by a control. Since the electrolyzer is embedded in the aqueous liquid, switching it on immediately results in an initiation.

Preferably, the heat generated is partially or completely initially stored in a heat storage device, from which it is released as needed to a liquid transport medium of at least one heat exchanger. The heat storage is particularly preferably designed as a latent heat storage. In addition to the thermally stored heat, it contains the latent heat of a suitable storage medium (e.g. a sodium-acetate-trihydrate-water mixture), which can be stored during the transition from the crystalline to the liquid state.

A needs-based control can control a device to be provided for this purpose for specifically triggering crystallization, so that a relatively large amount of heat can be provided upon request. It is clear that after the storage medium has completely crystallized, there is only thermal (residual) heat left, which can nevertheless also be used. It is also clear that by supplying an appropriate amount of heat at a sufficiently high temperature (e.g. at least 65 °C), crystallization can be reversed and the latent heat storage can thus be “charged” again, which preferably happens when a) there is no larger amount of heat is needed elsewhere, and b) the electricity required to operate the electrolyser is currently cheap (e.g. during the day by operating a PV system). The control is set up to recognize an external request for heat (e.g. if the temperature falls below a minimum temperature in the heating circuit of a heater or a hot water storage tank) and to react accordingly (switching on the electrolyser and/or triggering crystallization in the latent heat storage tank).

Also preferably, the heat released during condensation of the water vapor produced during combustion is fed to a Stirling engine or a gas turbine and/or converted into electrical energy by means of at least one Peltier element, which is temporarily stored and/or fed to the electrolyzer. Here too, to avoid repetition, reference is made to the explanations above.

According to one embodiment, the water recovered by condensation is fed back into the combustion chamber, so that there is a “closed” circuit of the water or the aqueous solution. Any components that cannot be broken down by the electrolyzer, for example the sodium hydroxide mentioned above, initially accumulate in the combustion chamber. However, essentially distilled water flows back from the return, so that the concentration of NaOH remains essentially constant.

According to another embodiment, fresh water or a fresh aqueous solution is supplied to the combustion chamber from outside. This is therefore an “open system”, as already described above.

Character description

• 1 einen schematische Schnittansicht eines erfindungsgemäßen Brenners;
• 2 eine schematische Überblickszeichnung eines als „geschlossen“ ausgestalteten Systems mit Heizaggregat;
• 3 eine schematische Überblickzeichnung eines als „offen“ ausgestalteten Systems.

The invention is explained below by way of example using figures. This shows

• 1 a schematic sectional view of a burner according to the invention;
• 2 a schematic overview drawing of a “closed” system with a heating unit;
• 3 a schematic overview drawing of a system designed as “open”.

In the 1 a schematic sectional view of a burner according to the invention is shown.

The burner 1 includes a combustion chamber 2 in which an aqueous solution W is accommodated. A layer of a flammable liquid B is placed on this, which floats due to its lower density. This can be ignited into a pilot flame using an energy source 3 (not shown separately). A liquid-free combustion chamber 4 remains above the flammable liquid B. According to an embodiment, not shown, the layer of flammable liquid (B) is omitted; instead, the pilot flame is fed by side-injected fuel (gas or liquid).

An oxygen supply 5 opens into the combustion chamber 4 at its upper edge, which comprises several openings into which ambient air can flow or be blown. The arrows without reference symbols indicate this inflow.

An electrolyzer 6 is arranged at the lower end of the burner 1. In the example shown, this includes two concentric electrodes 7A, 7B arranged one inside the other (electrical supply lines not shown). The two electrodes 7A, 7B are held together by means of a suitable holder 8.

A supply line (without reference number) leads into the lower area of the combustion chamber 2 and is connected to an expansion tank (not shown).

There is also a gas temperature sensor 9 for determining the temperature in the liquid-free combustion chamber 4, and a liquid temperature sensor 10 for determining the temperature in the liquid W, B. The electrical lines to a controller which records the measurement data and appropriately controls or regulates the electrolyzer and other components not shown are not shown. Among other things, this concerns a (need-based) injection 11 for the flammable liquid.

Like from the 1 As can be seen, the bubbles generated during electrolysis rise on the electrodes 7A, 7B through the two liquids W, B and reach the combustion chamber 4. There they hit the pilot flame fed by the flammable liquid B. Oxygen from the ambient air mixes with the hydrogen-oxygen mixture; The mixture ultimately burns, generating heat in the combustion chamber, which is then available for further use.

In the 2 A schematic overview drawing of a “closed” system with a heating unit is shown. All media flows are symbolized by corresponding arrows (without reference numbers). However, control lines and electrical signals have been omitted for reasons of clarity.

The roughly schematically drawn burner 1 can be seen in the lower area. This is fed with aqueous solution W from an expansion tank 12. Above the expansion tank 12, a tank 13 with a pump (not shown) for the flammable liquid B is shown. Both containers 12, 13 open into the combustion chamber 2. Atmospheric oxygen entered the combustion chamber 2 through the oxygen supply 5. The electrolyzer 6 is not shown.

The hydrogen-oxygen flame (not shown) burns in the combustion chamber 2 and rises through the flame tube 14. This is surrounded by a tube heat exchanger 15, which can be connected to the heating circuit of a heater (not shown) via supply lines 16.

Flame tube 14 and tubular heat exchanger 15 are embedded in a heat storage 17, which is designed as a latent heat storage. This is filled with a suitable storage medium (not shown). Somewhat away from the flame tube 14 and therefore exposed to less high temperatures than the tube heat exchanger 15 is a second heat exchanger, which is designed as a plate heat exchanger 18. This also has supply lines 19, by means of which it can be connected to a service water circuit (not shown). Alternatively, a tube heat exchanger can also be used (not shown). In order to retrieve the latent heat stored in the storage medium, the heat storage 17 includes device 24 for specifically triggering crystallization (shown only schematically), which is connected to the control (also not shown).

A pressure compensation tank 20 is connected to the heat storage 17; depending on requirements, storage medium can flow into it or flow back into the heat storage 17.

A heat buffer 21 is arranged at the upper end of the heat storage. This serves to reduce the temperature of the water vapor flowing upwards from the flame tube 14. Downstream of the heat buffer 21 there is a condenser 22 in which the cooled gas condenses to water. The interior of the capacitor 22 is not shown for reasons of clarity. To improve economic efficiency, a Stirling engine 25 is connected upstream of the capacitor 22. On the right side of the capacitor 22 in the picture there is a condensate line 23, which opens into the expansion tank 12. This creates a circuit for the aqueous solution, which is why the system shown can also be described as “closed”.

In the 3 An “open” system is shown - also schematically and omitting some already introduced components as well as control lines etc. This includes a burner 1 with an electrolyzer 6 similar to that in 1 shown, which is why the details are not described again. To the right of the burner 1, an expansion tank 12 is shown, in which the same liquid level prevails as in the burner 1. Aqueous solution enters the burner 1 through the supply line (without reference number). The layer of flammable liquid B provided according to one embodiment is not shown either not the alternative pilot flame that is to be provided, which is fed by fuel that is injected from the side and burns immediately.

While the burner 1 can be installed in a fireplace (not shown), the expansion tank 12 is preferably arranged outside of it. The same applies to the control, a power storage and other electrical components, which can be combined in a control box 24, for example. Although a heat storage system is conceivable, it is an issue with an open system 3 not provided.

Reference symbol list

1

burner

2

combustion chamber

3

Energy source

4

combustion chamber

5

Oxygen supply

6

Electrolyzer

7A,7B

electrode

8th

bracket

9

Gas temperature sensor

10

Liquid temperature sensor

11

injection

12

surge tank

13

Tank with pump

14

flame tube

15

Tubular heat exchanger

16

Leads

17

Heat storage

18

Plate heat exchanger

19

Leads

20

Pressure compensation tank

21

Heat buffer

22

capacitor

23

Condensate line

24

Switch box

25

Stirling engine

W

aqueous solution

b

flammable liquid

Claims (11)

Heating unit for generating heat from a combustible gas, the heating unit comprising a burner (1) for generating the heat and at least one heat exchanger (15, 18) for transferring the heat generated to a liquid transport medium, the burner (1) being operable with hydrogen gas is, characterized in that the burner (1) has the following components: - a combustion chamber (2) for receiving an aqueous solution (W), above which a liquid-free combustion chamber (4) remains, in which a pilot flame that can be fed by a fuel can be ignited ; - an oxygen supply (5) into the combustion chamber (4); - an electrolyzer (6) for water for producing hydrogen and oxygen from the aqueous solution (W), the fission products of which can be introduced into the aqueous solution (W) of the combustion chamber (2); so that the gas generated by electrolysis can rise through the aqueous solution (W) and burn together with supplied oxygen and the pilot flame in the combustion chamber (4) to generate heat, which can then be given off to the heat exchanger (15, 18). Heating unit after Claim 1 , wherein the fuel for the pilot flame is in the form of - a combustible liquid (B) or a combustible gas, which can be injected into the combustion chamber (4), or - floating on the aqueous solution (W). the layer of a flammable liquid (B). Heating unit after Claim 1 or 2 , wherein the flammable liquid (B) is an alcohol, and/or the energy source (3) can be operated electrically or mechanically, and/or the oxygen comes from the ambient air. Heating unit according to one of the Claims 1 until 3 , wherein the electrolyzer (6) has two electrodes (7A, 7B) arranged one inside the other and comprising metal grids, tubes or sheets. Heating unit according to one of the preceding claims, further comprising a heat accumulator (17), which cooperates with a flame tube (14) connected downstream of the burner (1). Heating unit according to one of the preceding claims, comprising a demand-controlled injection (11) for the fuel and/or a temperature-controlled triggering of the electrolysis. Heating unit according to one of the preceding claims, comprising - a pressure compensation tank (20) for the storage medium located in the heat storage (17), and/or - a second heat exchanger, the first heat exchanger being a tubular heat exchanger (15) which can be connected to the heating circuit of a house, and the second heat exchanger being a plate heat exchanger or tubular heat exchanger (18) which can be connected to the domestic water storage tank of a house. Heating unit according to one of the preceding claims, comprising a condenser (22) arranged downstream of the flame tube (14) for collecting and condensing the water vapor produced during combustion. Heating unit after Claim 8 , comprising at least one Peltier element connected to the capacitor (22) for converting the waste heat generated in the capacitor (22) into electrical energy, which can be temporarily stored and / or fed to the electrolyzer (6), and / or one to the capacitor (22) upstream Stirling engine (25). Heating unit after Claim 8 or 9 , comprising a condensate line (23) for returning the condensed water to the combustion chamber (2). Heating unit according to one of the preceding claims, wherein the aqueous solution (W) which can be introduced into the electrolyzer (6) comprises 10% sodium hydroxide.

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