EP2250448B1 - Cast-iron or aluminium sectional boiler - Google Patents

Description

The invention relates to a sectional boiler made of cast iron or aluminum, in particular a condensing boiler, according to the preamble of claim 1.

Such sectional boiler consist of several integrally cast boiler members, which are arranged one behind the other and water side connected by hubs. The water channels and water pockets formed by the boiler members are flowed through between the return connection and the supply connection. As a rule, generic sectional heating boilers have a lower return connection and a top feed connection, preferably in the respective hub. The hot gases flow from the combustion chamber via downstream hot gas flues to an exhaust gas outlet and release heat to the boiler water on their way.

In all previous boilers of this type, the links are arranged in series one behind the other. There is an annular front member to which a combustion chamber door or a burner plate can be attached, depending on the power size one or more similarly shaped middle links and a rear link. In this case, the combustion chamber extends through the front and middle links to the rear link, which forms the bottom of the combustion chamber with its lid-shaped design. All of the boiler members have similar external dimensions in these embodiments because they form parts of the combustion chamber, Heizgaszügen and water space over the entire boiler cross-section. Furthermore, boilers for low power ranges are known, which consist of only two or even only one boiler member.

With regard to the exhaust system and the efficiency of the heaters, a distinction is made between heating value technology and condensing boiler technology. For reasons of energy saving more and more condensing boilers are used. The design of their heat exchanger provides the opportunity to cool the resulting in the combustion of fuel and air moist exhaust gases below the Abgastaupunkt. The moisture of the exhaust gases condenses and in addition to the sensible heat, the heat of condensation is transferred to the heating water.

When used as a condensing boiler special emphasis must be placed on the choice of materials, because due to the composition of the fuel used and the combustion management, the exhaust gases are polluted and the accumulating condensate has various acids in low concentration. The components touched by condensation, such as heating surfaces, exhaust manifold and exhaust pipe must therefore be resistant to the acids, which is why it is customary to manufacture these components made of stainless steel, aluminum or plastic. Especially in the Ölbrennwerttechnik are generally used welded stainless steel heat exchangers, such as in the DE 10 2004 023 711 B3 disclosed as spiral tube winding. They offer the advantage of enduring the acid load without corrosion. Disadvantages are the high costs associated with the material as well as, especially in welded constructions made of sheet metal, the less favorable scaling conditions and the larger sizes which are difficult to assemble in spatially narrow conditions.

The heat exchangers of conventional calorifiers are often made of cast iron. They are characterized by high robustness and long life. Their construction of mostly identical casting segments allows cost-effective production and easy scalability with regard to different output sizes and offers good mounting options even under tight installation conditions. The material endures the short exhaust gas condensation phases very well at startup and cold heat exchanger. Only for condensing operation with a prolonged accumulation of condensation is cast iron in its present form and design not suitable.

Furthermore, from the DE 296 21 817 U1 a condensing boiler with integrated and hydraulically downstream compact heat exchanger made of corrosion-resistant material known. This compact heat exchanger is as a separate component of two enclosed shell-shaped boiler sections and separately connected on the water side. All boilers with downstream heat exchanger have the disadvantages that the assembly work is increased by the required pipe parts and the water-side resistance increases. The arrangement as a separate, external component also causes cooling losses, which must be reduced by a suitable thermal insulation.

An arrangement according to the preamble of claim 1 is made EP 0 127 881 A known.

The invention has the object to optimize a sectional boiler made of cast iron or aluminum, in particular with regard to compactness and robustness.

This is achieved with the features of claim 1 according to the invention. Advantageous developments can be found in the dependent claims.
The cast iron or aluminum sectional heating boiler is characterized in that annular gaps are provided between two adjacent members as heating gas flues which run approximately radially outward starting from the combustion chamber and open into an exhaust gas collecting space on the outside of the members. To form an annular gap, two adjacent links each have an associated geometry.

For this purpose, various embodiments are possible, namely that first, an annular gap at right angles to the central axis of the combustion chamber extends radially and straight outwards. In a second variant, an annular gap is radially curved and extends arcuately, similar to a turbine blade geometry, to the outside. In a third embodiment it is provided that an annular gap with an inclination to the central axis of the combustion chamber extends straight outwards. This is particularly useful with a vertical arrangement of the entire block of links, because then condensate can drain all the way down from a gap. Furthermore, an annular gap in the radial direction can also be wavy outward, in particular in order to increase the flow turbulence within a gap, so that an intensive heat transfer is achieved on the surfaces.

Advantageously, the width and / or the free cross section of an annular gap decreases from the combustion chamber to the outlet on the outside of the links, to achieve an adaptation to the cooling gas volume which decreases with the cooling. The heating gas contacted surfaces of the members, at least the gap forming surfaces, may be provided with a corrosion protection coating.

The exhaust gas collecting space on the outside of the members, in which the annular gaps open, extends as a hollow cylinder around the outer lateral surfaces of the members and is bounded by a jacket to the outside. This is sealingly received between radially outwardly projecting annular webs on the outside of the front and rear member.

The two anchor rods for holding the link block are arranged inside the hubs. Alternatively, to hold the link block together, a feed pipe for return water and / or discharge pipe for supply water disposed within the hubs may be used when provided with corresponding threads for tightening the assembly.
To form a forced flow, the upper and lower hubs between the return and flow connection can be mutually closed, in which case closure means are attached to the anchor rods, feed pipe and / or extraction pipe. Thus, an alternating overflow between two adjacent members in the upper and lower hub is ensured over the length of the link block.

At least two centering points or surfaces are provided on each member to maintain an exact gap between two adjacent links, which map the Rohgussabmessungen and Rohgusstoleranzen particularly well. In particular, the thickness of the limb has a direct influence on the gap width between two limbs. These centering points or surfaces are then decisive for the mechanical processing of the sealing or contact surfaces on the hubs, because it can be about the actual existing gauge after the casting process at the crucial point determine and then on the processing according to the desired and individual set exactly the right nominal dimension.

With the invention, a sectional boiler with the best suitability for condensing operation is created in which the positive material properties of cast iron or aluminum are selectively applied and used to ensure good heat transfer properties, compactness and robustness. It is collected corrosion-causing loads. The anticorrosion coating itself is according to the invention not only easy to apply and control, but it is also protected in the columns from possible mechanical stress. In addition to the simple production, the sectional construction also offers the advantage of being able to variably cover different lengths for different combustion and heat exchanger capacities by inserting further center elements. Nevertheless, then remain all front-mounted attachments and the water-side connections the same. Only the surrounding mantle around the exhaust manifold varies. Because of the low exhaust gas temperatures, this can even be made of plastic.

Fig. 1:

in einer perspektivischen Gesamtansicht mit einem Schnitt im oberen Eckbereich,

Fig. 2:

in einem vertikalen Längsschnitt durch eine Hälfte des gesamten Gliederblockes und

Fig. 3:

mit einen Mittelglied in perspektivischer Darstellung.

The drawing shows an embodiment of the invention. It shows a sectional boiler made of cast iron or aluminum:

Fig. 1:

in a perspective overall view with a section in the upper corner area,

Fig. 2:

in a vertical longitudinal section through one half of the entire block of links and

3:

with an intermediate member in perspective view.

The sectional boiler consists essentially of annular members, namely a front member 1, a lid-shaped rear member 2 and a plurality of middle members 3. These form a combustion chamber 4 and the annular water chambers 5 communicate with each other via hubs 6, 6 'in connection.

As Heizgaszüge respectively annular column 7 between two adjacent members 1, 2, 3 are provided, each extending from the combustion chamber 4 approximately radially outward and open into an exhaust gas collection chamber 8. To form an annular gap 7, two adjacent links 1, 2, 3 each have an associated geometry. In the illustrated embodiment arise by the curvatures of the members 1, 2, 3 four radially curved, annular column. 7

The exhaust gas collection chamber 8 extends as a hollow cylinder around the outer lateral surfaces of the members 1, 2, 3 and is bounded by a jacket 9 to the outside, which sealing between radially outwardly projecting annular webs 10 on the outside of the front and rear members 1, 2 is recorded.

Two anchor rods 11 for holding the link block are arranged within the hubs 6, 6 '. To this end, disk-like closure means 12 are attached to mutually close the upper and lower hubs 6, 6 'to form a forced flow between the return and supply ports.

Furthermore, there are at each member 1, 2, 3 for maintaining an exact gap between two adjacent links 1, 2, 3 three centering surfaces 13 of molded cam to accurately identify the respective present dimensions after the casting process and for the processing of the hub areas consulted.

Claims (13)

1. Cast-iron or aluminium sectional boiler, in particular a condensing boiler, having essentially annular sections, there being provided a front section (1), a cover-shaped rear section (2) and at least one middle section (3) which form a combustion chamber (4) with essentially surrounding hot gas flues and whose annular water spaces (5) are connected to one another via hubs (6, 6'), with a lower return-flow connection and an upper inflow connection, and with at least two anchor rods (11) for holding the section block together, characterized in that, as hot gas flues, there are respectively provided, between two adjacent sections (1, 2, 3), annular gaps (7) which each run approximately radially outwards proceeding from the combustion chamber and open into an exhaust gas manifold on the outer side of the sections.
2. Sectional boiler according to Claim 1, characterized in that, to form each annular gap (7), two adjacent sections (1, 2, 3) have a matching geometry.
3. Sectional boiler according to Claim 1 or 2, characterized in that an annular gap (7) runs radially and straight outwards at right angles to the central axis of the combustion chamber (4).
4. Sectional boiler according to Claim 1 or 2, characterized in that an annular gap (7) runs outwards in a radially curved manner.
5. Sectional boiler according to Claim 1 or 2, characterized in that an annular gap (7) runs straight outwards obliquely with respect to the central axis of the combustion chamber (4).
6. Sectional boiler according to Claim 1 or 2, characterized in that an annular gap (7) runs radially outwards in the form of a wave.
7. Sectional boiler according to one of Claims 1 to 6, characterized in that the breadth and/or the free cross-section of an annular gap (7) decrease(s) from the combustion chamber (4) to the discharge opening on the outer side of the sections (1, 2, 3).
8. Sectional boiler according to one of Claims 1 to 7, characterized in that those surfaces of the sections (1, 2, 3), at least those surfaces which form the gap (7), that are in contact with the hot gas, are provided with a corrosion protection coating.
9. Sectional boiler according to one of Claims 1 to 8, characterized in that the exhaust gas manifold (8) on the outer side of the sections (1, 2, 3), into which the annular gaps (7) open, extends as a hollow cylinder around the outer lateral faces of the sections (1, 2, 3) and is bounded in the outward direction by a jacket (9) which is received in a sealing manner between radially outward-projecting annular webs (10) on the outer side of the front and rear sections (1, 2).
10. Sectional boiler according to one of Claims 1 to 9, characterized in that the two anchor rods (11) for holding the section block together are arranged within the hubs (6, 6').
11. Sectional boiler according to one of Claims 1 to 10, characterized in that an injection pipe for return-flow water and/or an extraction pipe for inflow water, which is/are arranged within the hubs (6, 6'), serves to hold the section block together.
12. Sectional boiler according to one of Claims 1 to 11, characterized in that the upper and lower hubs (6, 6') are alternately closed so as to form a once-through flow between the return-flow connection and the inflow connection, closure means (12) being attached to the anchor rods (11), the injection pipe and/or the extraction pipe.
13. Sectional boiler according to one of Claims 1 to 12, characterized in that, for the purpose of maintaining an exact gap width between two adjacent sections (1, 2, 3), at least two centring points or centring faces (13), that indicate the casting dimensions and casting tolerances, are provided on each section (1, 2, 3), and that these centring points or centring faces (13) are decisive for the mechanical machining of the sealing faces or bearing faces on the hubs (6, 6').

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