US3857367A

US3857367A - Boiler

Info

Publication number: US3857367A
Application number: US00362414A
Authority: US
Inventors: G Giesen
Original assignee: BEONDU AG
Current assignee: BEONDU AG
Priority date: 1972-05-23
Filing date: 1973-05-21
Publication date: 1974-12-31
Anticipated expiration: 1991-12-31
Also published as: ES415016A1; GB1410095A; CH566531A5; LU67646A1; JPS4949236A; BE799751A; ATA448073A; ZA733398B; FR2185777A1; DE2325497A1; IT985131B; FR2185777B1; NL7206921A

Abstract

A boiler, usable for central heating, has at least one fire duct and, on either side thereof, ducts for a heat-transferring medium, normally water, the fire duct and the water ducts being formed by elements cast in one piece of an aluminum alloy. One side of the elements forms a component part of a fire duct and the other side a component part of the water duct, the elements being interconnected by welding.

Description

United States Patent 1191 Giesen Dec. 31 1974 I 9 BOILER 71 35 3/ 3 l 1 [75] Inventor: Gerardus Johannes Giesen, Tegelen, 4 233 Netherlands 3,385,356 5/1968 Assigneez Beondu A.G., Vanduz, Liechtenstein Coley et a1 22 Pl d: Ma 21, 1973 1 I e y Primary ExaminerKenneth W. Sprague PP 362,414 Attorney, Agent, or FirmAnthony A. OBrien [30] Foreign Application Priority Data May 23, 1972 Netherlands 7206921 [57] ABSTRACT A boiler, usable for central heating, has at -least one 2 "122/367 122/156 1 3 fire duct and, on either side thereof, ducts for a heat- 51 I t C F225 3/7/10 transferring medium, normally water, the fire duct and d C 367 A the water ducts being formed by elements. cast in one 1 0 care l22/l 1 6 piece of an aluminum alloy. One side of the elements forms a component part of a the duct and the other side a component part of the water duct, the elements [56] UNITE D S;T;:S SZ?FENTS being interconnected by welding.

533,395 1/1895 Page 122/367 10 Claims, 2 Drawing Figures PATENTEDDEB3 1 m4 857.- 367 I saw 2 or 2 BOILER both dimension and form. Simple and rapid maintenance is also a matter of importance in the installment of such a boiler in private dwellings.

It is an object of the invention to provide a boiler which fulfills all the above-mentioned objectives.

According to the invention, there is provided a boiler preferably a gas-fired central heating boiler, characterized by at least one fire duct adjoined on opposite sides by ducts which are connected in parallel for circulating therethrough a heat-transferring medium, such as water, the fire duct and the water ducts being divided by heat conducting elements cast in one piece of an aluminium alloy, one side of which defines a border of the fire duct and the other side a border of the water duct.

In a one-flue embodiment the boiler is therefore provided with one central fire duct and two ducts for the heat-circulating medium.

In previously known boilers the boiler elements or sections are cast of cast iron or steel, using cores for forming the duct hollows. Not only does this impose limitations in the design of the various ducts, because the cores used must be removable, but also sand residues from the core casting process may be left in the water ducts, which cannot be removed after casting. By constructing the heat transferring parts of the boiler out of a light metal in such a .way that one side thereof forms a component part of a fire duct and the other side a component part of a water duct, the water ducts and fire ducts can be adapted as much as possible to the heat transfer desired at each point, at minimum casting costs. The elements thus made can afterwards be secured by welding to form fire ducts and water ducts. Before welding, however, all surfaces are accessible to such an extent that any finishing operation, to obtain a desired surface texture for better heat exchange, can be carried out. The casting process without cores is particulary suitable for manufacturing boiler elements of light metal, for instance aluminium alloy, which ensures greater heat exchange than a cast iron or steel partition between a fire duct and a water duct.

Also according to the invention projections are formed on each fire duct-defining element on the fire duct side, the projections being shaped and located to provide maximum heat transfer in a flame zone of the fire duct immediately above a burner bed and a combustion gas zone of the fire duct located above th flame zone. the

Each fire duct wall is preferably completely covered with pyramid-shaped projections in the flame zone. Each fire duct wall is preferably covered in the gas zone with finger-shaped projections arranged in a pattern of laterally staggered horizontal rows, the projections extending out to the centre of the fire duct. Because these fingers contact each other in the centre of the fire duct and are staggered transversely to the direction of the gas flow, the combustion gases are forced to follow a labyrinth path in which turbulence accurs, which allows for good heat transfer. It is, for instance, possible with the boiler of the present invention to attain a gas temperature in the chimney of less than 200C at a flame temperature of approximately l200C.

In the boiler according to the invention it is preferred that the fingers have a diamond-shaped cross-section with a ratio between the diagonals of between 1:2 and 1:4, preferably 113. The fingers are preferably disposed with their longer diagonal in the direction of flow and with the distance or pitch between the fingers in each horizontal row approximately equal to the length of the short diagonal.

To aid in the removal of cores at the end of the casting process the fingers of the fire duct wall are faintly tapered towards the centre, preferably, in a ratio of 102/100, the length of the long diagonal at the smaller end being approximately l/lO of the length of the finger.

Each fire duct wall can also be provided with a system horizontally extending baffles of equal height on the water duct side of the heat conducting elements, which baffles define, together with the walls of the boiler which theycontact a labyrinth-shaped water passage extending over substantially the entire wall of the fire duct.

The water can be introduced to the water ducts at half the height of the boiler whenthe water ducts are connected in parallel and the path of the water can be restricted so that the inflowing water is first carried downwards and then guided upwards along a zig-zag path.

The construction of the boiler of the invention is very simple: for it is composed of a small number of elements, for example, four; it has a small width, and

' needs only one row of burners which are extremely easily accessible for maintenance purposes. The efficiency is nevertheless very high, because a light metalguaranteeing a high heat transfer is used, and because the specific casting process to be employed has made it'possible to cover the fire duct and the 'water duct walls with an optimum number of heat exchange promoting elements.

The completely symmetrical construction will also allow for adaptation to the space available for the boiler.

In a one-flue embodiment of the boiler according to the invention, the boiler dimensions being x 30 x 22 cm, a capacity of 30000 kcal/h is feasible.

One embodiment of the boiler according to the invention will be described by way of example with reference to the accompanying drawings, of which FIG. 1 is a side view of the boiler with some parts being broken away, and showing the upper portion slightly inclined towards the reader, and

FIG. 2 is a cross-sectional view on the line II-Il of FIG. 1.

As shown in FIG. 2, the boiler has four elements arranged in pairs, being mirrorsymmetric relative to one another. These elements are outer cover plates 1 and 2 between which symmetrically disposed heat conducting elements 3 and 4 are located.

Elements 3 and 4, made of light metal, form partitions between a central fire duct 5 and two

water ducts

6 and 7.

The lower portion of fire duct 8 constitutes a flame zone, above which a combustion gas zone 9 is located. The walls of the fire duct in flame zone 8 are completely covered with pyramid-shaped projections 10, while in the flame zone finger-

shaped projections

11, 11 extend towards one another from each element 3, 4.

The finger-shaped projections are arranged on the respective fire duct walls in a pattern of rows of

fingers

11,11 extending transversely to the movement of the combustion gas, the fingers being staggered in successive rows. As is shown in particular in the perspective view at the upper portion in FIG. 1, the fingers have a diamond-shaped cross-section, the long diagonal of the diamond extending vertically, that is to say, in the direction of flow of thecombustion gases. The mutual distance between the fingers 11 and 11' in each row i.e., the pitch, is approximately equal to the length of the short diagonal and fingers 11 of the top row shown are horizontally staggered over the pitch distance relative to fingers 11 in the subjacent horizontal row.

Fingers l1 and 11' meet in the centre of the fire duct.

Baffles 12 extend into

water ducts

6 and 7 and are integrally formed of elements 3 and 4. Together with cover plates 1 and 2 the baffles define a labyrinth or zig-zag-shaped water passage, in which the water flows from the bottom to the top. In the embodiment shown the water is introduced through inlets 13 located approximately at half the height of the boiler, so that it first blows downwards and then follows the meandering path upwards as indicated by arrows W in FIG. 1.

The water can be supplied through a T-piece. Under the boiler a burner 14 is located.

- it is obvious that the bottom of a boiler which is not of the gas-fired type can also be water-cooled.

We claim:

1. A boiler comprising a vertically extending outer wall,

a burner means,

two vertically extending heat conducting elements secured parallel to and at a distance inside of said outer wall,

a fire duct defined between said heat conducting ele ments, said burner means being located in'said fire duct, and

water ducts extending between said heat conducting elements and said outer wall for circulating a heat transfering medium therethrough, v

each of saidheat conducting element being a single separately cast piece of light metal.

2. A boiler as claimed in claim 1 wherein the ligh metal is an aluminum alloy.

3. A boiler as claimed in claim 2 wherein each heat conducting element is provided with a plurality of horizontally-extending baffles, the baffles extending into the water ducts and contacting said outer wall to define zig-zag type paths for the water through said ducts.

4. A boiler as claimed in claim 3 wherein the water' an outer wall enclosed the boiler, vertical heat conducting elements each cast in one piece of an aluminum alloy, the fire duct being defined between said elements, the water ducts being defined between said elements and the outer wall, and finger shaped projections on the heat conducting elements extending into thecenter of the combustion gas'zone of said fire duct to provide maximum heat exchange, said projections being arranged in staggered horizontal rows.

6. A boiler as claimed in claim 5 wherein each finger shaped projection has a cross section in the form of a diamond having longer and shorter diagonals, the ratio of the length of the longer and shorter diagonals being between 2:1 and 4:1.

7. A boiler as claimed in claim .6 wherein the longer diagonals of the diamond shaped cross section of each projection are oriented vertically and when each of the projections in each of the horizontal rows is separated from the next by a distance equal to the length of the shorter diagonal of the diamond.

8. A boiler as claimed in claim 6 wherein each of said projections tapers slightly as it extends into the fire duct and wherein the length of the longer diagonal is approximately 1/10 the length of the projection.

9. A boiler as claimed in claim 5 wherein aplurality of horizontally extending baffles extend from each of said heat conducting elements into the water ducts to water duct and is first conducted downward before entering the zig-zag type path.

Claims

1. A boiler comprising a vertically extending outer wall, a burner means, two vertically extending heat conducting elements secured parallel to and at a distance inside of said outer wall, a fire duct defined between said heat conducting elements, said burner means being located in said fire duct, and water ducts extending between said heat conducting elements and said outer wall for circulating a heat transfering medium therethrough, each of said heat conducting element being a single separately cast piece of light metal.

2. A boiler as claimed in claim 1 wherein the light metal is an aluminum alloy.

4. A boiler as claimed in claim 3 wherein the water is introduced to each water duct intermediate its length and is conducted downward therein before entering said zig-zag type path and wherein each of the water ducts is connected in parallel with the other.

5. A boiler comprising a vertical fire duct having a combustion gas zone and a flame zone containing a flame therein, a vertical water duct on either side of said fire duct, an outer wall enclosed the boiler, vertical heat conducting elements each cast in one piece of an aluminum alloy, the fire duct being defined between said elements, the water ducts being defined between said elements and the outer wall, and finger shaped projections on the heat conducting elements extending into the center of the combustion gas zone of said fire duct to provide maximum heat exchange, said projections being arranged in staggered horizontal rows.

7. A boiler as claimed in claim 6 wherein the longer diagonals of the diamond shaped cross section of each projection are oriented vertically and when each of the projections in each of the horizontal rows is separated from the next by a distance equal to the length of the shorter diagonal of the diamond.

9. A boiler as claimed in claim 5 wherein a plurality of horizontally extending baffles extend from each of said heat conducting elements into the water ducts to contact the outer wall to define a zig-zag type path for the water through said duct.

10. A boiler as claimed in claim 9 wherein water is introduced at an intermediate level in the height of the water duct and is first conducted downward before entering the zig-zag type path.