Device for heating a medium

Abstract

The invention relates to a device (1) for heating a medium, comprising a burner unit (2) and a flame tube (3). The burner unit (2) generates flue gas, and the flame tube (3) has a flue gas inlet (30), a longitudinal axis (31), a casing (32) extending along the longitudinal axis (31), and an end face (33) lying opposite the flue gas inlet (30), wherein the flue gas reaches the flame tube (3) from the burner unit (2) via the flue gas inlet (30), multiple recesses (34, 34') are located in the casing (32), and the recesses (34, 34') have different dimensions and / or are distributed asymmetrically on the casing (32). The longitudinal axis (31) lies on a central plane, a first side (32') and a second side (32") of the casing (32) being defined by the central plane, and recesses (34) on the first side (32') have smaller dimensions than recesses (34') on the second side (32").

Description

[0001] The present invention relates to a device for heating at least one medium. The medium is, for example, air, water, or any other liquid. For example, air and a liquid (e.g., water) can also be heated.

[0002] Air heaters are known in the prior art that have a burner unit for burning, for example, an air-gas mixture. The resulting flue gas transfers its thermal energy to the (room) air to be heated via a heat exchanger. Alternatively, the heat is transferred to a liquid, e.g., water. Combination devices are also known that serve to heat both air and water. It is also known that the flue gas is first passed through a flame tube located within the heat exchanger. This can also lead to improved and less polluting combustion. Examples of flame tubes can be found in DE 21 39 504 C3, EP 1 681 519 A2, DE 32 33 321 C2, or DE 100 19 890 C2. The flame tubes described therein are open on the side facing away from the burner.A cover for the front side is disclosed in DE 10 2006 054 821 A1 or can also be found in US 2,779,398 A.

[0003] If the flame tube is surrounded by a heat exchanger, there is a risk of uneven heat distribution with local overheating. Depending on the device's use, this can potentially have a negative impact on the material's durability. Furthermore, the uneven heat input reduces the heat exchanger's effectiveness.

[0004] The object underlying the invention is to propose a device for heating at least one medium, the flame tube of which brings about an improvement over the prior art with regard to heat distribution.

[0005] The invention solves the problem by a device according to claim 1.

[0006] Because the flame tube of the device is arranged horizontally, the first side with the smaller cutouts is located above the second side with the larger cutouts due to gravity, with the first side being located above the second side. Consequently, the flue gas rises and passes through narrower cutouts than the flue gas that leaves the flame tube at a lower level. In the casing and thus on the side of the flame tube there are cutouts whose size and position are optimized for even heat distribution and a suitable exit of the flue gas from the flame tube. One target criterion for optimization is a flow pattern that is as evenly distributed as possible. Furthermore, the cutouts are asymmetrically distributed, at least with regard to their dimensions, i.e. with regard to their opening or average areas.The larger cutouts are on one side of the casing and the smaller cutouts are on the other side.

[0007] It has been found that the flue gas generally takes the shortest possible path for optimal flow. Therefore, in one embodiment, the recesses are designed and arranged in such a way that a geometrically longer path, starting from the flue gas inlet, is associated with larger dimensions and therefore larger opening areas. The dimensions of the recesses thus increase in the direction away from the burner unit. Therefore, in this embodiment, the recesses located closer to the burner unit have smaller dimensions and therefore smaller opening areas.

[0008] In one embodiment, the flame tube is surrounded by a heat exchanger, so that the shape and distribution of the recesses are such that the flue gas flows essentially evenly over the heat exchanger. Therefore, in one embodiment, the recesses are particularly designed and arranged such that a geometrically longer path, toward the flue gas outlet from the heat exchanger, is associated with larger dimensions and therefore larger opening areas. Furthermore, in one embodiment, the shape and distribution are such that a pressure loss along the flame tube is essentially constant.

[0009] In one embodiment, the invention relates to a burner / heat exchanger system (or to a device with a burner unit and a heat exchanger) with a centrally arranged burner and a one-sided exhaust gas discharge.

[0010] In one embodiment, the flame tube has a cylindrical shape with a circular or elliptical base.

[0011] One embodiment provides that the device further comprises a flue gas outlet, and that the flue gas flows from the flame tube to the flue gas outlet. In one embodiment, the flue gas outlet is located above the flame tube, counter to gravity. In particular, a one-sided exhaust gas routing is realized via the flue gas outlet. In one embodiment, the flue gas outlet is located along a long side of the flame tube or the heat exchanger. In one embodiment, the flue gas outlet is located more towards the height (relative to the longitudinal axis of the flame tube) of the burner unit than at the height of the front side of the flame tube.

[0012] In one embodiment, the flame tube is located horizontally within a housing. In this embodiment, the flame tube is located within a housing.

[0013] One design involves having smaller cutouts on the side of the casing facing the flue gas outlet than those on the side facing away from it. The flue gas, which thus takes a geometrically shorter path from the interior of the flame tube to the flue gas outlet, passes through smaller cutouts than the portion of flue gas that initially moves away from the flue gas outlet and therefore experiences correspondingly less draft toward the outlet.

[0014] One embodiment provides that a majority of the recesses are located in a section of the casing that is small compared to the overall length of the casing. In this embodiment, the recesses, or at least a majority of the recesses, are located in a section along the longitudinal axis that is small compared to the overall length. In one embodiment, the section comprises less than half the overall length, and in another embodiment, it comprises one-third or one-quarter of the overall length.

[0015] One design involves the recesses being located in an area between the last third and the last quarter of the shell along the longitudinal axis in front of the front end. In this design, the recesses (or at least a majority of them) are located at the rear end of the flame tube, facing away from the burner unit. This has the advantage that the combustion educts are significantly more or even completely converted in the flame. This reduces the exhaust emissions in terms of pollutants such as CO, NOx, or unburned hydrocarbons.

[0016] One embodiment involves the front end being at least partially or completely closed. In this embodiment, only a small portion of the flue gas can exit the flame tube through the front end – in the case of partial closure – or not at all – in the case of complete closure. This is in contrast to a flame tube with an open front end, as is known in the prior art.

[0017] One embodiment provides that the recesses are essentially circular holes or (elongated) slots.

[0018] One embodiment is that the device further comprises a heat exchanger, and that the flame tube is located at least partially within the heat exchanger. Depending on the design, the heat exchanger essentially has the basic shape of a cylinder or cone on the inner side facing the flame tube. Depending on the design, the flame tube is arranged concentrically or eccentrically within the heat exchanger.

[0019] In one embodiment, the heat exchanger has a substantially uniform internal profile in which the flame tube is located. In one embodiment, the flame tube is arranged centrally in the heat exchanger.

[0020] The flue gas outlet is located on one long side of the heat exchanger.

[0021] In one embodiment, the heat exchanger extends essentially in a horizontal direction.

[0022] One embodiment provides for the burner unit to burn a fuel-air mixture. The fuel can be, for example, gas or a suitably prepared liquid fuel, such as diesel or gasoline.

[0023] In detail, there are numerous possibilities for designing and developing the device according to the invention. Reference is made, on the one hand, to the claims subordinate to claim 1 and, on the other hand, to the following description of exemplary embodiments in conjunction with the drawings. They show: Fig. 1a section through a schematic representation of the device Condition 3: Fig. 2a spatial representation of the flame tube.

[0024] The Fig. 1 shows a schematic diagram of a device 1 for heating air and water. For this purpose, a fuel-air mixture is burned in the burner unit 2, the fuel being, for example, a gas. The resulting flue gas passes through the flame tube 3 and the recesses 34, 34' (cf. Fig. 2 ) into the interior of the heat exchanger 4 and from there to the flue gas outlet 50, which is connected, for example, to a chimney (not shown here). The flue gas flows horizontally through the flame tube 3 from the flue gas inlet 30. Thus, the longitudinal axis 31 of the flame tube 3 is horizontal. The heat exchanger 4 is circularly cylindrical. The surrounding units related to the conduction of the air or water to be heated are not shown for clarity.

[0025] The flame tube 3 is in the Fig. 2 It has a casing 32 extending along the longitudinal axis 31 and an end face 33, which is completely closed in the variant shown. The flue gas can thus escape only through the recesses 34, 34' in the casing 32. As can be seen, the recesses 34, 34' are located in the end of the flame tube 3 facing away from the flue gas inlet 30 or the end face 33. The flue gas must therefore pass through the flame tube 3 over a longer distance. This enables a more complete conversion of the combustion products, so that fewer harmful substances are produced and discharged.

[0026] In the illustrated embodiment, the recesses 34, 34' are designed as circular holes with different diameters. Due to the horizontal positioning of the flame tube 3 in the device, the casing 32 of the flame tube 3 has a first 32' (or upper) side and a second (or lower) side 32". Since (cf. Fig. 1 ) the flue gas outlet 50 is located above the flame tube 3 and also due to thermal buoyancy, the flow-technically shorter path for the flue gas is towards the upper side 32'. On the upper side 32' there are recesses 34 with smaller dimensions, so that smaller opening areas are also produced there. On the lower side 32", the recesses 34' are arranged with larger dimensions. Therefore, there the flue gas is discharged from the flame tube 3 after a longer flow path over larger cross-sections.

Claims

1. A device (1) for heating a medium, comprising a burner unit (2) and a flame tube (3), wherein the burner unit (2) generates flue gas, wherein the flame tube (3) has a flue gas inlet (30), a longitudinal axis (31), a casing (32) extending along the longitudinal axis (31), and an end face (33) opposite the flue gas inlet (30), wherein the flue gas passes from the burner unit (2) into the flame tube (3) via the flue gas inlet (30), wherein a plurality of recesses (34, 34') are located in the casing (32), wherein the flame tube (3) is arranged horizontally, wherein the longitudinal axis (31) is in a central plane, wherein a first side (32') and a second side (32") of the casing (32) are formed by the central plane, so that the first side (32') is arranged above the second side (32"), and wherein the recesses (34, 34') have different dimensions, characterized in that with respect to the central plane, the recesses (34, 34') are distributed asymmetrically on the casing (32), so that the recesses (34) on the first side (32') have smaller dimensions than the recesses (34') on the second side (32").

2. The device (1) according to claim 1, wherein the device (1) further has a flue gas outlet (50), and wherein the flue gas passes from the flame tube (3) to the flue gas outlet (50).

3. The device (1) according to claim 1 or 2, wherein a majority of the recesses (34, 34') is located in a portion of the casing (32) which is small relative to an overall length of the casing (32), and wherein the recesses (34, 34') are located between a last third and a last quarter of the casing (32) in front of the end face (33).

4. The device (1) according to any of claims 1 to 3, wherein the end face (33) is partially or completely closed.

5. The device (1) according to any of claims 1 to 4, wherein the device (1) further includes a heat exchanger (4), and wherein the flame tube (3) is at least partially located in the heat exchanger (4).

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