Boiler

The invention relates to a boiler comprising a combustion chamber which is surrounded at least in part by a combustion gas flue that is embodied as a primary heat exchanger. The combustion gas flue is enclosed at least in part by a water-conducting housing while a water-conducting secondary heat exchanger that is hydraulically connected to the housing is mounted downstream of the combustion gas flue. According to the invention, the combustion chamber is surrounded at least in part by the secondary heat exchanger.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The invention relates to a boiler having a combustion chamber with a heat insulating block.

2) Description of Related Art

German Patent Application Publication No. DE 34 25 667 A1 discloses a boiler having primary and secondary heat exchangers, wherein the secondary heat exchanger is located behind the combustion chamber when viewed in the axial direction, hence a compact design is not possible because of the necessary burn-up length.

SUMMARY OF THE INVENTION

A boiler of the type specified initially is manufactured and sold by the applicant under the product name “Vitolaplus” and is accordingly known (seeFIG. 3).

The “Vitolaplus” boiler consists of a combustion chamber which is surrounded at least in part by a combustion gas flue that is embodied as a primary heat exchanger. In this case, in order to ensure clean combustion, the combustion chamber must have a certain length, the so-called burn-up length. The aforementioned combustion gas flue is furthermore surrounded at least in part by a water-conducting housing while a water-conducting secondary heat exchanger that is hydraulically connected to the housing, that is configured as helically tube-shaped and through which heating gas flows radially from inside to outside, is mounted downstream of the combustion gas flue. The heating gas coming from the burner thus flows initially from the combustion chamber into the combustion gas flue and there releases heat to the water in the housing. Following the combustion gas flue, the heating gas flows radially from inside to outside through the flow gap of the downstream, flue-gas-condensing helically tubular heat exchanger and there again, at a correspondingly lower temperature level, releases heat to the water flowing through the secondary heat exchanger.

From the heat engineering point of view, this condensing boiler has proved extremely successful. It has a very high normal supply level of up to 103%.

The object of the invention is to configure a boiler of the type specified initially more compactly in order to reduce the required space and therefore the required mounting volume, whilst ensuring the necessary burn-up length inside the combustion chamber.

According to the invention, it is also provided that the combustion chamber is surrounded at least in part by the condensing secondary heat exchanger.

The stipulation “at least in part” expresses the fact that not all the parts of the secondary heat exchanger must surround the combustion chamber, wherein the larger the enclosed part, naturally the better the invention is implemented.

In other words, the compactness of the boiler according to the invention is achieved by at least a large part of the secondary heat exchanger surrounding the combustion chamber, i.e. the external dimensions of the heat exchanger are now necessarily defined by the aforementioned burn-up length of the combustion chamber and not by the size of the secondary heat exchanger. In this way, the entire boiler can be configured as shorter when viewed in the axial direction of the combustion chamber. In addition, the heat released by the combustion chamber is now also supplied to the secondary heat exchanger, whereby a further improvement in the utilisation of heat is achieved. The silencer structure provided in the known prior art (Vitolaplus) behind the combustion chamber is omitted or is mounted, if required, downstream of the secondary heat exchanger.

As in the Vitolaplus design, in the solution according to the invention it is preferably but not necessarily provided that the secondary heat exchanger is configured as helically tube-shaped and heating gas flows radially therethrough from inside to outside. In this case, in particular, the constructively advantageous solution is obtained that the combustion chamber is surrounded by the secondary heat exchanger, forming an annular chamber, wherein the combustion gas flue preferably opens out directly into the annular chamber. This will be explained more precisely further below.

It is particularly preferably provided in this case that the combustion chamber comprises a combustion chamber sleeve which is configured to be withdrawable from the combustion chamber in the axial direction. This stipulation makes it possible if necessary, since the combustion chamber is surrounded by the secondary heat exchanger at least in part, to clean this (the secondary heat exchanger) and also the combustion gas flue with the combustion chamber sleeve removed. The combustion chamber sleeve in which the heat insulating block can also be arranged depending on the embodiment of the boiler (a pot-type combustion chamber is obtained in this way) is therefore also used to a certain extent as a flue gas flow guide or closure element and at the same time forms an inner boundary wall for the aforementioned annular space and the combustion gas flue.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2show two different embodiments of the boiler according to the invention. If no further indications are given, the following explanations always apply to both embodiments.

The boiler according to the invention consists of a cylindrical combustion chamber1, wherein this is surrounded concentrically at least in part by a combustion gas flue2embodied as a primary heat exchanger and wherein the combustion gas flue2is in turn surrounded concentrically at least in part by a water-conducting housing3. A water-conducting secondary heat exchanger4that is connected hydraulically to the housing3, that is configured as helically tube-shaped in this case and through which heating gas flows radially from inside to outside, is mounted downstream of the combustion gas flue2. This secondary heat exchanger4is located in a housing6that defines on the one hand an annular chamber5still to be explained and on the other hand, another annular-chamber-shaped flue gas collecting chamber7surrounding the secondary heat exchanger4, wherein the flue gas collecting chamber7has a flue gas extraction connection (not explicitly shown but indicated by the upwardly pointing arrow) for removing the flue gas. If necessary, a silencer can be connected to this flue gas extraction connection.

As in the known prior art shown inFIG. 3, in the boiler according to the invention it is preferably provided that the secondary heat exchanger4is configured in the form of a helically wound tubular helix, having a flat flow gap8through which radial flow can take place. Furthermore, in order to avoid corrosion damage, it is provided that the secondary heat exchanger4is made of stainless steel. In addition, a heat insulating block13(for example, made of Vermiculite) is located in the combustion chamber1to deflect the heating gas jet.

A burner10(here an oil burner, but a gas burner is equally well possible) is always located on one front side9of the combustion chamber1. The access11from the combustion chamber1to the combustion gas flue2is located, as desired, in the area of the burner-side front side9(seeFIG. 1) or in the area of the other front side12facing away from the burner (seeFIG. 2).

For all the embodiments of the boiler according to the invention, it is now essential that the combustion chamber1is surrounded at least in part by the secondary heat exchanger4.

The aforementioned annular chamber5in which the combustion gas flue2opens out directly is preferably obtained in this case. Naturally, in an alternative embodiment of the secondary heat exchanger, a less direct flow guidance from the combustion gas flue to the secondary heat exchanger can also be provided.

In the embodiment according toFIG. 1, the secondary heat exchanger4surrounds the combustion chamber1in the area of the heat insulating block13and in this way absorbs the heat released by the heat insulating block13.

For the same burn-up length of the combustion chamber as mentioned initially and as shown by a comparison withFIG. 3, the embodiment according to the invention results in a considerably more compact boiler in which the direct heat emission from the combustion chamber can be additionally used by the secondary heat exchanger. The hitherto necessary extremely expensive structure for flow guidance of the heating gas from the primary heat exchanger to the secondary heat exchanger is eliminated.

As can be seen particularly clearly fromFIGS. 4 and 5, it is advantageously provided that the combustion chamber1comprises a combustion chamber sleeve14comprising a shell plate16and optionally a base plate17(closure plate), which are configured as withdrawable from the combustion chamber1in the axial direction (relative to the longitudinal axis of the cylindrical combustion chamber1).

As can be seen fromFIGS. 1 and 2this solution is provided in principle in both embodiments (secondary heat exchanger4located on burner side or facing away from burner), wherein in the arrangement of the secondary heat exchanger4facing away from the burner (FIGS. 1,4and5) the combustion chamber sleeve14has a base plate (closure plate)17on one side and is configured as a pot-type combustion chamber. The rod-shaped handle element18projecting (seeFIG. 1) into the area of the burner10is used for withdrawing the pot-type combustion chamber in which the heat insulating block13is preferably located.

Due to the withdrawal (in the embodiment according toFIG. 2this is easily possible after removing the burner-side terminating wall), if necessary both the combustion chamber1together with the combustion gas flue2and also the annular chamber5(without the combustion chamber sleeve14, the annular chamber5becomes a cylindrical chamber—seeFIG. 5) are easily accessible and can accordingly easily be cleaned. This possibility is not provided in the prior art shown inFIG. 3; this has proved to be particularly advantageous with regard to the boiler according to the invention.

Constructively, it is furthermore provided that the combustion chamber wall14forms a boundary wall of the combustion gas flue2and the annular chamber5, wherein finally the combustion gas flue2consists of cast iron segments15with radially inwardly directed ribs, whose free ends rest on the combustion chamber sleeve14and define its position in the combustion chamber1.

REFERENCE LIST