DE29516284U1 - Double-wall chimney - Google Patents

Description

"Two-wall chimney"

The invention relates to a double-shell chimney according to the preamble of claim 1, which uses the heat of the flue gas through heat exchange.

Three-layer chimneys are known with an inner pipe that carries the flue gas, a thermal insulation layer, a casing that supports the thermal insulation layer and ventilation ducts between the casing and the thermal insulation layer. Since such chimneys are sometimes operated below the dew point, the ventilation ducts serve to dry the thermal insulation layer, since it becomes moist or sooty due to the condensation that occurs when the temperature falls below the dew point.

It is also known to provide a ventilation channel between the casing of the chimney and the inner pipe, through which, for example, the cellar can be ventilated.

It is the object of the present invention to provide a chimney in which the heat of the flue gas is used in an energy-saving manner.

This object is solved by the features claimed in claim 1.
Further details emerge from the subclaims.

In the present invention, an air channel is provided between the casing and the inner tube, through which air flows, for example in the opposite direction to the flue gas, i.e. from top to bottom. The air is heated by heat exchange with the flue gas. For this purpose, the outer circumference of the inner tube is designed as a profile, through which the outer circumferential surface of the inner tube is enlarged. The air flows along the outer circumferential surface of the inner tube inside the inner tube, so that a heat exchange takes place between the air and the inner tube. Furthermore, a heat exchange takes place between the inner circumferential surface of the inner tube and the flue gas, so that overall a heat exchange takes place between the flue gas and the air.

In an advantageous embodiment of the invention, the preheated air is fed to a fireplace. It can serve directly as combustion air or preheat the combustion air of the fireplace using another heat exchanger. The preheated air can also be used to heat the interior of a house, for example the basement. For good heat transfer in the inner pipe, this can advantageously be made of ceramic or plastic.

In the following, the various embodiments will be explained in detail using the attached figures:
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Figure 1 shows a horizontal section through the double-shell

Chimney of the present invention,

Figure 2 shows alternative profiling of the outer circumference

of the inner tube,

Figure 3 shows a side view of the profiled inner tube and

Figure 4 shows a functional diagram of the double-shell chimney

of the present invention.

The structure of the double-shell chimney of the present invention is described with reference to Figure 1:

An inner pipe 1 is provided inside the chimney, which carries the flue gas in its interior 5. Radially on the outside, the chimney is formed by a casing 3. This casing 3 can also have devices that serve to support the inner pipe 1. An air duct 2 is formed between the casing 3 and the inner pipe 1. As can be seen from Figure 4, flue gas from a fireplace 6, which can be a boiler, for example, flows through the inner pipe 1 to the upper mouth 7 of the chimney, where it exits. Air enters the air duct 2 at the opening 8 and flows through it to the lower foot area of the chimney. During this flow, the air is heated according to the present invention by heat exchange with the flue gas flowing upwards via the inner pipe. For this purpose, a surface-enlarging profile is provided for the outer peripheral surface of the inner pipe 1. Possible designs of such a profiling are shown in Figures 2 and 3. The

Profiling can be achieved by vertical ribs on the outer circumferential surface of the inner tube 1 (Figure 3). Four possible designs of such ribs are shown in Figure 2. The ribs can be semicircular (4a), semicircular recesses (4b), trapezoidal (4c) or sinusoidal (4d). However, any profiling that increases the surface area of the inner tube is possible for the present invention. For example, an increase in the surface area of the inner wall of the inner tube 1 is also possible. In order to achieve the best possible heat exchange, the inner tube 1 is made of a material with the highest possible thermal conductivity. For example, the inner tube is made of ceramic or plastic.

The air entering at the opening 8 and flowing through the air duct 2 to the base of the chimney, where it is preheated by heat exchange with the flue gas, can be fed to a fireplace 6 (Figure 4). In a further embodiment of the present invention (not shown), the heated air is not fed to a fireplace, but to the interior of a house, for example the basement, in order to heat it.

Since the flue gas is deliberately cooled in the chimney according to the present invention, in contrast to the chimneys of the prior art, the temperature in the upper part of the chimney can fall below the dew point. The condensate that forms flows down the inner wall of the inner pipe 1 and is collected in a condensate container 9. A cleaning opening 10 is also provided.
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Claims (5)

EXPECTATIONS 1. Double-shell chimney with an inner pipe (1) carrying the flue gas, a casing (3) surrounding the inner pipe and an air duct (2) located between the casing and the inner pipe, characterized in that the outer circumferential surface of the inner pipe (1) adjacent to the air duct has a surface-enlarging profile for heat exchange between the flue gas in the inner pipe (1) and the air in the air duct (2). 2. Double-shell chimney according to claim 1, characterized in that the profiling consists of vertical ribs. 3. Double-walled chimney according to claim 1 or 2, characterized in that the air preheated by heat exchange with the flue gas is fed through the air duct to a fireplace. 4. Double-shell chimney according to one of the preceding claims, characterized in that the inner pipe (1) consists of a ceramic. 5. Double-shell chimney according to one of the preceding claims, characterized in that the inner pipe (1) consists of a plastic.