EP0296276A2 - Boiler - Google Patents

Abstract

The boiler consists of a water-bearing housing (4), in which a combustion chamber (3) with at least one transition chamber (3'') is arranged, out from which a number of heating gas pipes (1) are conducted to a smoke gas collecting chamber (12) with a take-off connection pipe (11). The diameter of the heating gas pipes (1) is 7-16 cm, preferably 9-13 cm. The heating gas pipes (1) have on the inside transfer surface enlargements (2) in the form of radially oriented, straight-running or helically wound longitudinal ribbings (2'), the heating gas pipes (1) being arranged around or partially around and above or above the combustion chamber (3). By means of this design, the number of heating gas pipes (1) is reduced by 20 to 25% in relation to a boiler of the same capacity and thus the outlay in terms of manufacturing and welding work for such boilers is reduced. <IMAGE>

Description

The invention relates to heating boilers for medium (approx. 60 to 1,800 KW) and higher output ranges (approx. 1,800 - 6,000 KW) according to the preamble of the main claim.

Such boilers are well known and in use. In writing, reference can be made to brochures 9444136-3 and 9444137-2 of Viessmann Werke, but also to DE-A-28 24 185, in which, in contrast to the objects in the brochures, the heating gas pipes are arranged around the combustion chamber. These known heating gas draft tubes are internally smooth tubes with a small diameter and in order to be able to accommodate a performance-adapted transmission surface for the boiler in question, either a large number of tubes with the corresponding production outlay must be installed, or, as in the case of the DE- A -28 24 185 a separate secondary heat exchanger can also be provided with the corresponding manufacturing and installation costs in order to be able to use the heat generated in the heating boiler in a satisfactory manner. In view of the large number of heating gas draft tubes and the smallest possible dimension of the boiler housing according to brochure 9444136-3, the tubes are arranged above the combustion chamber, but this results in a complex design of the surrounding walls of the water-bearing housing ses in the form of two superimposed and partially intersecting cylinders. In the known boilers for higher performance ranges according to brochure 9444137-2, the enclosing housing is desirably cylindrical in the case of an eccentrically arranged combustion chamber, but this leads to a relatively large diameter of the enclosing housing, which would also not be able to be reduced significantly if all hot gas draw tubes in e.g. two layers would be arranged around the combustion chamber.

The invention is therefore based on the known prior art, the task, based on this prior art, to improve heating boilers of the type mentioned at the outset so as to substantially reduce the production outlay in terms of introducing the necessary heat exchange surface.

This object is achieved with a boiler of the type mentioned according to the invention by the features stated in the characterizing part of the main claim. Advantageous further developments result from the subclaims.

This design, which is based not only on the idea of simply increasing the cross sections of the heating gas draw tubes or their diameters, but at the same time also of increasing the transmission area within the tubes, makes it possible to use tubes with to be able to provide an enlarged but still justifiable diameter in a smaller number and thus reduced installation effort. In the case of boilers with comparable performance, the number is advantageously reduced by 20-25%. Theoretically, it would also be possible to reduce the number of small cross-sectional tubes that have been used up to now, if one ensured an increase in the transmission area inside these smaller diameter tubes. This is opposed to the fact that such small-diameter pipes were extremely difficult to equip with such enlargements. Inner ribs on tubular structures are known according to GB-A -562 435 and JP-A-59-66648, but in the first case this is a large-diameter combustion chamber in which the attachment of the inner ribs does not cause any problems and in the second case is an internally and externally finned heat exchanger with radial gas inlets and outlets, which for this reason alone is not suitable for installation in boilers.

The use of pipes with a relatively large diameter in the specified range is advantageously more accessible to automatic welding, the welding error rate is reduced accordingly and the number of approaches of the welding device is also reduced. Since, viewed from the front of the pipe inlets, the area occupied by them is also reduced, the lock door of the boiler can also be advantageously kept small.

It is preferred to design the boiler in such a way that the heating gas pipes are kept at least one to two times their pipe diameter longer than the combustion chamber with a corresponding distance from the rear wall of the housing to the combustion chamber floor. Since this results in more available and effective heat transfer area, this measure also advantageously contributes to being able to reduce the number of pipes required, which should represent the necessary heat transfer area, or to develop one of the heating gas pull pipes as an internally smooth bypass pipe, ie to dispense with an enlargement of the heat transfer surface in this tube, this bypass tube being provided on the collecting chamber side with a bimetal-operated closure. In view of the most compact possible design with the aim of keeping the outer dimensions as small as possible, the boiler can advantageously also be designed in such a way that the combustion chamber wall, with the exclusion of its base area, is provided at least at one point with a wavy curvature directed into the interior of the combustion chamber and adjacent heating gas pipes to the Curvature are arranged closer, which will be explained in more detail.

The requirement of arranging the new, large-diameter heating gas pipes above the combustion chamber, which are provided with enlargements of the heat transfer area, for boiler or combustion chambers for the medium output range, takes over consideration that for this performance range the smallest possible width dimensions are of interest because they can be installed in installation rooms, while this is not so important for boilers with larger output ranges, since there are usually sufficiently large access options to the installation rooms. Apart from that, there is of course nothing to prevent the pipes from being arranged above the combustion chamber in boilers for larger output ranges.

The specified size range for the diameters of the heating gas pull-down pipes is due to the fact that heating surface enlargements can still be easily introduced into the pipes, for example, at approx. 70 mm in diameter, while much larger pipes with a diameter of more than 16 cm can affect both the entire boiler geometry the external dimensions as well as in terms of expedient and space-saving accommodation of such pipes.

Insofar as central free spaces remain in the heating gas draw tubes between the ends of the longitudinal ribs, gas displacement inserts in an elongated rod shape can be arranged in them without further ado and in a known manner.

However, the main advantage of the whole new type of boiler design is essentially independent of whether the heating gas flues are above the combustion chamber or around it Combustion chamber are arranged around that the detour of an internal transfer area enlargement, the previously large number of heating gas pipes can be reduced while maintaining the heat transfer area available and thus the manufacturing costs. Regarding the above-mentioned dimensioning of the heating gas pull pipes in relation to the length of the combustion chamber, it should also be noted that the rear wall of the water-carrying housing has been moved as close as possible to the rear wall or the bottom of the combustion chamber, whereby the heating gas pull pipes inevitably almost the same length as that Had to have a combustion chamber. This principle is specifically abandoned in the present boiler in a further development, with a relatively small extension of the water-carrying housing and the heating gas draw pipes overall allowing more transmission area to be accommodated, which, seen as a whole, can correspond to the transmission area of an entire pipe.

The heating gas draft tube, which is preferably designed according to claim 2, should be designed in its condensate-critical area in such a way that even in unfavorable operating phases this area can be quickly heated up and that overall the heat conversion capacity of such a tube is increased and thus ultimately a smaller number of tubes for a specific one amount of heat to be implemented can be provided and this with the proviso that the inflow-side high heating surface load and the changing gas volume are taken into account.

Through this tube, the total heat transfer area of the tube is increased, in particular in the condensate-critical area, on the other hand, special measures are taken in the inflow area so that the very hot heating gases cannot have a negative effect on the heating gas draft tube and, furthermore, the total draft resistance is limited held, namely by an enlarged inflow cross-section in this area, which can be accomplished by various measures, namely, for example, by obliquely cutting the inflow-side rib ends, the beginning of the ribbing only further back in the hot gas draft tube and / or in combination with a specially designed filler.

The heating boiler is explained in more detail below with the aid of exemplary embodiments.

• Fig. 1 einen Längsschnitt durch einen Heizungskessel für den mittleren Leistungsbereich;
• Fig. 2 einen Blick in Pfeilrichtung A in den Heizkessel gemäß Fig. 1;
• Fig. 3 eine der Fig. 2 entsprechende Darstellung aller­dings mit anderer Anordnungsform der Heizgaszug­rohre;
• Fig. 4 einen Schnitt durch einen Heizungskessel für höhe­re Leistungsbereiche;
• Fig. 5 einen Querschnitt durch den Heizkessel gemäß Fig.4;
• Fig. 6 einen Schnitt durch das Heizgaszugrohr;
• Fig. 7 einen Querschnitt durch das Heizgaszugrohr im Bereich der Verrippung;
• Fig. 8 einen Querschnitt durch das Heizgaszugrohr im Bereich der Verrippung in anderer Aus­führungsform;
• Fig. 9 perspektivisch das vordere Ende eines zy­lindrisch noch nicht geschlossenen, aber bereits mit der Rippenfaltung versehenen Blechzuschnittes, aus dem das Innenrohr ge­bildet wird und
• Fig.1o in Außenansicht das Innenrohr in besonderer Ausführungsform

It shows schematically

• 1 shows a longitudinal section through a heating boiler for the medium power range.
• 2 shows a view in the direction of arrow A into the boiler according to FIG. 1;
• FIG. 3 shows a representation corresponding to FIG. 2, however, with a different arrangement of the heating gas draft tubes;
• 4 shows a section through a heating boiler for higher power ranges;
• 5 shows a cross section through the boiler according to Figure 4.
• 6 shows a section through the heating gas draft tube;
• 7 shows a cross section through the heating gas draft tube in the region of the ribs;
• 8 shows a cross section through the heating gas draft tube in the area of the ribs in another embodiment;
• 9 is a perspective view of the front end of a sheet metal blank that has not yet been closed cylindrically, but is already provided with the rib fold, from which the inner tube is formed, and
• Fig.1o in external view of the inner tube in a special embodiment

The exemplary embodiment of the heating boiler according to FIGS. 1-3 is one for so-called medium power ranges in the order of 60-1,800 KW. Such boilers consist of a water-bearing housing 4, in which a reversing combustion chamber 3 with burner-side deflection or overflow chamber 3ʺ is arranged, from which heating gas pipes 1 are guided to a flue gas collection chamber 12 with an exhaust connection piece 11. As can be seen in particular from FIG. 2, these heating gas draft tubes 1 are now provided with a comparatively large diameter, which in the exemplary embodiment shown and with a combustion chamber diameter of approximately 50 cm is approximately 10 cm. This increase in diameter alone is not sufficient to compensate for the associated loss of transmission area with a corresponding reduction in the number of pipes, which is aimed at because of the installation effort, but the heating gas draw tubes 1 are, as can be seen, with transmission area enlargements 2 in Form of radially oriented longitudinal ribs 2ʹ, through which the loss of transmission area is fully compensated. These longitudinal ribs 2ʹ are either axially extending ribs, but it can also be a helically twisted ribs. The ribs, as indicated in Fig. 1,9, are advantageously provided with slots 2ʺ for gas swirling. The ribs 2ʹ are in the rest of Fig. 7,8 inserted as a folded, prefabricated insert tightly fitting into the respective tube 16, so that double-walled tubes arise. On the other hand, the larger cross-sectional dimensioning of the heating gas draft tubes creates the possibility of easily equipping such relatively large diameter tubes with such transfer area enlargements. As far as and as shown, there are central free spaces 1ʹ between the ends of the longitudinal ribs, round rod-like displacer inserts 5 and 21 are arranged in them, which allow the flowing heating gases to flow in the spaces between the longitudinal ribs. The smaller number of these heating gas draft tubes 1 also means that there is no longer a large tube package made up of a large number of small-diameter and internally smooth tubes, which can only be accommodated in an additional part of the water-carrying housing which is attached at a correspondingly greater cost, as previously described. As illustrated in FIGS. 2, 3, the cylindrical or largely cylindrical combustion chamber and the relatively few arranged above it can be used in these exemplary embodiments Warm gas flue pipes are advantageously easily accommodated in an enclosing housing which is cylindrical or oval in cross section, which is of course more expedient than having to divide the housing. Since it is of considerable interest for such heating boilers for medium power ranges to be able to be installed in installation rooms as narrow as possible in width, the oval shape of the enclosing housing is preferred, as shown.

A further reduction in width and, depending on the arrangement of the heating gas draw tubes, a reduction in height, if necessary, can be achieved with an embodiment according to FIG. 3, in which the combustion chamber wall 10, with the exclusion of its base region B, as shown, at two points, each with a wave-shaped curvature 13 directed into the combustion chamber interior is provided, wherein adjacent Heizgaszugrohre 1 are arranged closer to the curvature. As can be readily seen, the volume of the combustion chamber is somewhat reduced as a result, but not the transmission area represented by the combustion chamber wall 10. As can be seen, one of the heating gas draft tubes is designed as an internally smooth bypass tube 8 with a bimetallic closure 9 on the collecting chamber side (see FIG. 1). The bimetal actuating the closure 9, which is arranged in the collecting chamber 1, is adjusted or arranged such that the closure is in the cold state of the boiler remains open. At the start of the burner, not shown here, a partial flow of the exhaust gases can flow out of the combustion chamber 3 directly through the bypass pipe 8, which offers less resistance, whereby the chimney is immediately subjected to a higher temperature and condensation in the chimney is avoided. Since sufficient dimensioning area is available due to the dimensioning and design of the other heating gas draft tubes 1, the arrangement of such a bypass tube with a correspondingly large diameter is readily possible.

As can be seen from FIG. 1, the rear wall 6 of the water-carrying housing 4 is arranged relatively far from the bottom 7 of the combustion chamber 3. As a result, the heating gas draft tubes 1 must be dimensioned correspondingly longer, but this is quite desirable since an additional transfer area gain can be achieved. This gain in length alone replaces, for example, the loss of additional transmission area in the smooth inner bypass tube 8.

4, 5 is intended for larger output ranges and in the order of magnitude of, for example, 1,800 - 6,000 KW. The combustion chamber diameter at ∼ 2,300 KW is approx. 100 cm, whereby the heating gas pipes 1 have a diameter of 13 cm. The number of heating gas pipes required for such a combustion chamber size and such power ranges is in spite of a correspondingly large number Individual diameters, as can be seen, are relatively large, i.e. for a power of the order of 2,300 KW, around twenty such heating gas pipes have to be accommodated in the water-bearing housing, but with a pipe diameter of only 7 cm and pipes without an internal transmission area increase, around ninety pipes would have to be installed be provided and welded in! If arranged above the combustion chamber, it would only be possible to accommodate such a number in a two-part housing as mentioned in the introduction. For this reason, the Heizgaszugrohre 1 are arranged in the water-carrying housing 4 around the entire combustion chamber, which has the advantage that the enclosure housing can be cylindrical in cross section. Lateral curvatures 13, as indicated by dashed lines in FIG. 5, could, however, be provided when the heating gas draw-in tubes were brought up accordingly, so that even such a boiler could be reduced in terms of its width dimensions.

In the following, reference will be made to the detailed design of a single heating gas draft tube 2, as shown in FIGS. 6 to 10.

As can be seen from Fig. 6, in which various embodiments are summarized, the outer tube 14 is formed with spacing 24 in partial areas close to the inner tube 15 in a heat-conducting manner, the Ab Stands 24 of the tightly fitting partial areas 23 are getting larger towards the outflow side and the thermally tightly fitting partial areas are formed all around the inner tube 15. The inner tube 15 can be smooth up to half the length of the entire heating gas draft tube 2, that is to say formed without internal ribbing and then be provided with longitudinal ribs 2ʹ extending in the longitudinal direction, which can extend radially to the center Z of the heating gas draft tube 2, as in FIG. 7 indicated by dashed lines.

If the internally finned inner tube 15 extends into the inflow area 25, the longitudinal ribs 2ʹ are formed in this area towards the inflow opening 25ʹ with obliquely extending ends 27, as is also indicated by dashed lines in FIG. 6. The interior of the hot gas draft tube, referred to here as inflow region 25, can easily extend up to half the length of the entire hot gas draft tube. If the longitudinal ribs 2ʹ do not extend radially to the center Z, as also shown in FIGS. 6 to 8, a filler 21 is arranged in the free space between the rib ends 26, the inflow-side part 21ʹ of which is designed as a slender cone, so that the To meet the requirement that the inflow area has a larger cross section than the subsequent cross section in the heating gas draft tube 2. On the one hand, the inflowing Heating gases are pushed into the interstices between the fins and there the direct heat transfer to the fins is increased and, on the other hand, the total resistance of the heating gas draft tube is not increased or is not increased significantly, since in the inflow area of the inner tube 15 a decrease in flow resistance has been gained to a certain extent. In particular, if the filler is only inserted further back, a vortex 22 in the shape shown, for example, can be arranged on the inflow side of the filler 21 or 21 bz, with which the filler 21 can also be easily removed from the pipe in the case of intended cleaning.

As mentioned, the requirement mentioned can also be met by a smooth, ie longitudinal rib-free design of the inner tube 15 in the inflow region 25, as can also be seen in FIG. 6. As such, the smooth part 14 and the part of the inner tube 15 provided with longitudinal ribs 2ʹ could be formed from one piece, but this would be associated with a considerably complex manufacturing device. As shown, the smooth part and the part of the inner tube 15 provided with longitudinal ribs 2ʹ are therefore formed as separate tube parts 14, 17, which are inserted into the outer tube 16, closely adjoining one another. Both pipe parts 14, 17 can simply be butted against one another, overlapped at their joint 18 or welded to one another.

The introduction of the inner tube 15 into the outer tube 16 is absolutely unproblematic, since this must have sufficient oversize and otherwise no preferred heat transfer guide bridges can be pressed against the outer tube and brought into contact with the inner tube.

As can be seen in particular from FIGS. 7 to 9, the part of the inner tube 15 provided with longitudinal ribs 2ʹ is formed from a sheet metal blank 2o provided with rib folds 19 and cylindrically bent. The single-layer end bends 28 on both longitudinal edges of the sheet metal blank 2o form a rib in mutual abutment and when the sheet metal blank 2o is joined together (see FIGS. 7, 8). This embodiment would of course also be used if the longitudinal ribs extended over the entire length of the tube.

As can be seen from FIGS. 7, 8, the ribs can have the same or different heights and, if necessary, at least partially and depending on the inner diameter size, even as indicated in dashed lines in FIG. 7, up to the center area (this of course without arrangement a packing) of the inner tube 15 are sufficient. The production of such ribs is absolutely unproblematic, since, as mentioned, the inner tube 15 is preferably formed from a sheet metal blank 20 which is readily accessible to such deformation on suitable devices.

The cylindrically closed sheet metal tube with the longitudinal ribs 2ʹ can then also be twisted in a suitable device, so that the longitudinal ribs 2ʹ, as indicated in FIG. 10, have a helical course.

As can also be seen from Fig. 6, the outer tube 16 is formed on the inflow side over a larger portion of the smooth tube part 14 of the inner tube 15, that is, there are no poorly heat-conducting cavities, but in this area of the smooth inner tube 15 there is one above it Whole region 29 extending thermal conduction bridge, in which case the heat conduction bridges following in the flow direction become smaller or the distances between these heat conduction bridges become larger.
Another embodiment is also included in FIG. 6, which is even cheaper than that described so far. This is because the longitudinal ribs 2ʹbis extend into the inflow region 25, and in order to avoid scaling of the ribs and to achieve a cross-sectional enlargement, the rib height toward the inflow opening 25ʹ, as indicated by dashed lines, can advantageously be of diminishing dimensions. The filler 21 can also extend into this area 29, but is formed at least in this area in the form of a slender cone 21,, so that the inflowing, very hot heating gases have a larger volume available.

Claims (13)

1. A heating boiler, consisting of a water-carrying housing, in which a combustion chamber with at least one transfer space is arranged, from which several heating gas pipes are led to a flue gas collecting chamber with a flue connection, characterized in that the diameter of the heating gas pipes (1) is 7-16 cm, is preferably 9 - 13 cm, and the tubes (1) have internal transmission surface enlargements (2) in the form of radially oriented, straight-extending or helically twisted longitudinal ribs (2ʹ), the tubes (1) around or partially around and above or above the combustion chamber (3) are arranged. 2. heating boiler, in particular according to claim 1,
characterized in that the heating gas draft tubes (1) are formed from an inner tube (15) and an outer tube (16), the inner tube (15) being provided with longitudinal ribs (2ʹ) extending in the longitudinal direction at least over the greater part of its length with regard to their height (H) extend at most to the center (Z) of the draw tube (1) or that at a lower height (H) a filler (21, 21ʹ) is arranged in the free space between the rib ends (26);
that in the inflow area (25) of the heating gas draft tube (1) the free flow cross section is dimensioned larger with the same cross section of the outer tube (16) than the adjoining flow cross section of the heating gas draft tube (1) and that the part of the inner tube provided with longitudinal ribs (2ʹ) 15) is formed from a sheet metal blank (20) provided with rib folds (19) and cylindrically curved. 3. Boiler according to claim 2, characterized in that the longitudinal ribs (2ʹ) in the inflow region (25) to the inflow opening (25ʹ) are provided with obliquely cut ends (27). 4. Boiler according to claim 2 or 3, characterized in that at least the part arranged in the inflow region (25) (21ʹ) of the packing (21) is tapered. 5. Boiler according to claim 2, characterized in that in the inflow region (25) the inner tube (15) is designed as a rib-free tube part (14). 6. A boiler according to claim 5, characterized in that the smooth and provided with longitudinal ribs (2ʹ) part of the inner tube (15) as separate tube parts (14, 17) and are used next to each other in the outer tube (16). 7. Boiler according to one of claims 2 to 6, characterized in that between two longitudinal ribs (2ʹ) with maximum height at least one longitudinal rib (2 ‴) is arranged with a reduced height. 8. Boiler according to one of claims 1 to 7, characterized in that the Heizgaszugrohre (1) at a corresponding distance from the rear wall (6) to the combustion chamber floor (7) are kept at least one to two times their pipe diameter longer than the combustion chamber (3rd , 3ʹ). 9. Boiler according to one of claims 1 to 8, characterized in that rod-shaped gas displacement inserts (5) are arranged in the free spaces between the ends of the transmission surface enlargements (2) arranged in the tubes (1). 1o. Boiler according to one of claims 1 to 9, characterized in that one of the heating gas draw tubes is designed as a smooth bypass tube (8) with a bimetallic closure (9) on the collecting chamber side. 11. Boiler according to one of claims 1 to 1o, characterized in that the combustion chamber wall (10), at the exclusion of its base region (B), is provided at least at one point with an undulating curvature (11) directed into the interior of the combustion chamber and adjacent heating gas pull pipes (1) the curvature are arranged. 12. Boiler according to one of claims 1 to 11, characterized in that the folded longitudinal ribs (2ʹ) are provided with swirling slots (2ʺ). 13. Boiler according to Claims 1 and 12, characterized in that the sheet metal blank (2o) for the formation of the inner tube (15) to be folded is provided with pre-punched swirl slots (2 die) which are arranged perpendicular to the longitudinal extent of the sheet metal blank (2o).

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