DE29722328U1 - Heating device - Google Patents

Description

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Joh. Vaillant GmbH u. Co. GM 1625

The invention relates to a heating device according to the preamble of claim 1.

In known heating devices of this type, the flow through the honeycomb body is in one direction, with the honeycomb body usually defining a mixture space with one end face and an exhaust gas space with its second end face. However, this results in the disadvantage that it is difficult to adequately extract the heat generated during the conversion of a fuel gas-air mixture.

A further disadvantage of the known solutions is that the honeycomb bodies exhibit a significant thermal expansion in the transverse direction and for this reason can only absorb this thermal expansion with considerable effort.

The aim of the invention is to avoid these disadvantages and to propose a heating device of the type mentioned at the outset, in which this thermal expansion can be compensated.

According to the invention, this is achieved in a heating device of the type mentioned at the outset by the characterizing features of claim 1.

The proposed measures have the advantage that the honeycomb body only has to have a relatively low thermal expansion in the transverse direction of the channels, since the

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If the surface of the honeycomb body does not have a uniformly high temperature, the thermal expansion is much better balanced than in the case of a honeycomb body through which air flows in only one direction.

The features of claim 2 result in a very simple structure, whereby a substantially uniform load is also achieved across the cross-section of the honeycomb body.

The features of claim 3 result in the advantage that excessive heating of the honeycomb body in its lateral edge zones is avoided. This makes it possible to achieve a very uniform thermal load on the honeycomb body, which also increases the service life of the honeycomb body.

The features of claim 4 result in a frequent deflection of the fuel gas-air mixture, so that the honeycomb body only has to have a small thermal expansion in the transverse direction of the honeycomb body and small temperature differences in the longitudinal direction of the channels.

The features of claim 5 enable a better extraction of the heat generated by the catalytic conversion of the fuel gas-air mixture, since the proposed measures achieve an increase in the heat-radiating surfaces of the honeycomb body.

The features of claim 6 result in a good extraction of the heat generated by the conversion in the honeycomb body. It is also advantageous to provide the features of claim 7.

The features of claim 8 make it possible to vary the flow-through cross-section of the honeycomb body, whereby an additional modulation, in addition to the variation of the

gas throughput. All that is required is to move the two covers against each other so that a more or less large cross-sectional area of the honeycomb body is covered.

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

Fig. 1 to 4 show schematically various embodiments of heating devices according to the invention.

The same reference symbols indicate the same details in all figures.

The heating device according to the invention has a honeycomb body 2 arranged in a combustion chamber 1. The combustion chamber 1 is delimited by double walls 3 through which a heat-absorbing medium flows. The honeycomb body 2 is kept at a distance from a wall 4 that is to delimit the combustion chamber 1 at the bottom.

Walls 6 extend upwards from the upper end face 5 of the honeycomb body 2, which delimit inflow areas 7 and are provided with inlet openings 8 for a premixed fuel gas-air mixture. The inflow areas 7 are delimited upwards by horizontal walls 9, so that closed inflow areas 7 are created with the exception of the inlet openings 8.

A heat exchanger 10 is arranged above the walls 9.

The channels 11 of the honeycomb body 2 are only coated with a catalyst in the area between the vertical walls 6, whereas the channels in the area below the inflow areas 7 are only coated with a catalyst in their two end areas 12.

Between the lower front side 13 and the wall 4 there remains a space 14 through which the mixture is diverted. An ignition electrode 15 is arranged in the area of this space 14.

When such a heating device is in operation, a fuel gas-air mixture flows into the inflow areas 7 via the inlet openings 8 and flows through the channels 11 in the side areas of the honeycomb body 2. In the process, part of the fuel gas-air mixture is catalytically converted and heats the honeycomb body 2.

The remaining fuel gas-air mixture emerging from the lower end face 13, which is mixed with exhaust gases, is diverted in the space 14 and flows upwards in the central areas of the honeycomb body 2, whereby the remaining fuel gas-air mixture is completely converted. The exhaust gases that are created in this process emerge from the upper end face 5 of the honeycomb body 2 between the walls 6 and flow through the heat exchanger 10, giving off their heat to it. Furthermore, the heat radiation from the honeycomb body 2 also acts on the heat exchanger 10 and heats it up.

When the heater is started, the mixture flows into the honeycomb body via the inflow areas 7 and flows through it without any conversion taking place. The mixture is ignited in the area of the flow-through space 14. This heats the honeycomb body 2 so that it gradually reaches the working temperature of the catalyst and the catalytic conversion begins. As a result, the heating device increasingly goes into the operation described above.

The embodiment according to Fig. 2 differs from that according to Fig. 1 only in that in the inflow areas 7 delimited by the walls 6 and the double walls 3, deflection walls 16 are arranged, which alternately extend downwards from the walls 9 or the lower end face 13 of the honeycomb body 2 and upwards from the wall 4 or the upper end face 5 of the honeycomb body 2. Between

see the free ends of the deflection walls 16 and the opposite walls 9, or 4 overflow gaps 17.

The fuel gas-air mixture is therefore diverted several times in the inflow area 7 and flows through the channels 11 of the honeycomb body 2 several times, whereby in the end areas 12 of the honeycomb body 2 it is converted and thus heat is generated due to the catalytic coating. Finally, the already partially converted fuel gas-air mixture, together with the exhaust gases that have already been generated, flows through the middle area of the honeycomb body 2 from bottom to top, whereby in this middle area between the walls 6 the channels 11 are continuously coated with a catalyst. The remaining fuel gas-air mixture is completely converted. The exhaust gases then flow through the heat exchanger 10 and give off their heat.

In the embodiment according to Fig. 3, a mixture line 18 opens into a mixture chamber 19, whereby the opening of the mixture pipe 18 is covered by a spherically shaped perforated plate 20 in order to achieve a better distribution of the mixture. The mixture chamber 19 is also delimited at the top by a double wall 21 through which the water to be heated flows. The mixture chamber 19 is delimited at the sides by double walls 22 through which the water flows, which at the same time also delimit overflow channels 23 leading away from the mixture chamber 19, which are further delimited by double walls 24 through which the water flows.

These double walls 24 have recesses 25 in which a honeycomb body 2' is held. The double walls 24 end above horizontally extending double walls 9' which delimit inflow areas 7 and through which the water to be heated flows. The inflow areas 7 are further delimited by vertically extending walls 6 which connect to the intermediate walls 10 of the honeycomb body (2') and extend to the lower end face 13 of the honeycomb body 2'.

Furthermore, deflection walls 26 are arranged on the lower end face 13 of the honeycomb body 2', which with their free ends define overflow gaps 27, which are further delimited by the horizontal double wall 21.

In the embodiment according to Fig. 3, the channels 11 of the honeycomb body 2' are continuously coated with a catalyst.

During operation, a fuel gas-air mixture flows into the mixture chamber 19 via the mixture line 18 and then flows into the inflow channels 7 via the overflow channels 23. From there, the mixture flows downwards through the honeycomb body ²¹ and is partially converted in the process. The heat generated is coupled out into the double walls 24 and 25.

The remaining mixture, including the exhaust gases produced by the conversion, are redirected around the deflection walls 26 and flow upwards through the central area of the honeycomb body 2', whereby the rest of the mixture is converted. The exhaust gases act on a heat exchanger. Part of the heat produced by the conversion is coupled out by radiation into the horizontal double walls 21 and 9' and the double walls 24, 25 and 22.

In the embodiment according to Fig. 4, the honeycomb body 2" is divided, with the areas of the honeycomb body 2" located in the area of the inflow areas 7 being higher than the central area of the honeycomb body 2".

This significantly improves heat extraction by radiation, with the radiant heat being absorbed by the double walls 24 and 21.

Furthermore, the ignition electrode 15 is arranged on the upper side of the central region of the honeycomb body 2".

Furthermore, a cover 28 is arranged in the center of the upper end face 5 of the middle area of the honeycomb body 2". Two further covers 29 are arranged on the lower end face 13 of the honeycomb body 2", which in one position cover essentially the same channels 11 of the honeycomb body 2" as the fixed cover 28. The covers 29 can be removed from one another by means of a spindle 30, whereby a larger number of channels 11 can then be covered. This enables modulation of the power of the heating device in a larger power range than is possible by modulating the amount of fuel gas alone.

The operation of the heater according to Fig. 4 is essentially the same as that according to Fig. 3. The embodiment according to Fig. 4, however, results in a better extraction of the heat by radiation,

Claims (1)

Joh. Vaillant GmbH u. Co. GM 1625 EXPECTATIONS Heating device with a burner arranged in a combustion chamber (1) and formed by a catalytically coated honeycomb body (2, 2', 2") with continuous channels (11), characterized in that at least one wall (6) is provided which runs parallel to the channels (11) and delimits an inflow region (7) of a fuel gas-air mixture, which extends away at least from an end face (13) of the honeycomb body (2, 2', 2") having openings in the channels, and the end faces of the honeycomb body (2, 2 ¹ , 2") are held at a distance from a wall (4, 21) delimiting a flow-through space (14). Heating device according to claim 1 , characterized in that walls (6) delimiting inflow regions (7) are provided, between which a central region through which exhaust gases can flow remains. 9.12. Heating device according to claim 1 or 2, characterized in that the honeycomb body (2, 2', 2") is coated with a catalyst throughout only in its central region and in its lateral regions is coated with the catalyst only in its regions (12) close to the end faces. Heating device according to claim 2, characterized in that in the lateral regions of the honeycomb body (2) in which the channels (11) are only partially coated with the catalyst, deflection walls (16) are arranged which extend away from the end faces (5, 13) of the honeycomb body (2) and alternately delimit overflow gaps (1.7) between walls (4, 9) running parallel to the end faces of the honeycomb body (2). Heating device according to claim 2, characterized in that the sections of the honeycomb body (2") which extend on the inflow side up to the walls (6) delimiting the inflow region are arranged offset from its central region in the direction of the longitudinal extension of the channels (11). Heating device according to claim 1, characterized in that the honeycomb body (2 ¹ , 2") with its walls running parallel to the channels (11) is arranged between a heat-absorbing medium can flow through walls (3, 24). 7. Heating device according to one of claims 1 to 6, characterized in that an end face (13) of the honeycomb body (2\ 2") is held at a distance from a double wall (22) through which the heat-absorbing medium can flow. 8. Heating device according to one of claims 1 to 7, characterized in that a cover (28) is arranged on one end face (5) and at least one further adjustably held cover (29) is arranged on the opposite end face (13), which is displaceably held on the end face (13) of the honeycomb body (2', 2").