EP0583574B1 - Gas-fired boiler - Google Patents

Abstract

The invention relates to a gas-fired boiler, consisting of a water-carrying casing (1), in which there is arranged a combustion chamber (3) equipped with burner (2) and between which combustion chamber and the outlet connection piece (4) of a waste gas-collecting chamber (5) is arranged a residual heat exchanger (NT), through which the heat-exchange media can flow and which has inflow and outflow connections (6, 7) for the medium to be heated. According to the invention, the at least one residual heat exchanger (NT) is constructed in the form of a pocket (9), through which gas can flow axially and which is wound spirally between two parallel planes (E), and of which the main cross-sectional axis (HA), which is substantially larger than its cross-sectional width (B), is directed parallel to the winding axis (15). The residual heat exchanger (NT) is arranged in the uncooled waste gas-collecting chamber (5), which is assigned as a separate constructional unit to the water-carrying casing (1), the overall cross-section of the residual heat exchanger (NT) against which the heat-supplying medium flows substantially corresponding to the opening cross-section (8) of the combustion chamber (3) which is open towards the residual heat exchanger (NT) and is circular in cross-section. <IMAGE>

Description

The invention relates to a gas boiler.

Boilers of the type mentioned are generally known and in use, so that no special printed evidence is required in this regard. Depending on the size and design of such boilers, the secondary heat exchangers have different constructions, e.g. in the form of several pockets arranged parallel to one another, around which the heating water flows, or in the form of so-called lamella blocks formed from one or more pipes, the lamellas being the outer ribs of the pipes form. In boilers of the first type, the hot water is usually prepared in separate hot water tanks and those of the second type, which are generally of a lower capacity, by using pipes in the hot water pipes through which the warming process water is passed through, the heating water must be at a high temperature, but this is associated with a strong tendency to calcification. Regardless of whether heating boilers or process water are to be heated with such boilers, the production of such secondary heat exchangers is definitely quite complex and, if the bags are concerned, also their integration into the boiler, since tight connections from bag to bag be produced or the bags must be individually welded into corresponding connection openings of the boiler housing. Such an integration effort does not exist in the case of secondary heat exchangers designed in the form of lamella blocks, but in order to obtain sufficiently large heat transfer surfaces at all, the pipes or the pipes have to be provided with external ribbing with considerable effort. In addition, the secondary gases flow from the heating gases, viewed in cross section, essentially in a circular flow, which circular shape the above-mentioned secondary heat exchangers do not ideally correspond to.

Taking into account the current trend towards rising construction costs and property prices and the inevitably associated with it Reduction of living space is therefore becoming increasingly important for heaters or boilers with low heat output, and the invention is based on the task of creating a boiler which takes these trends into account and can be dimensioned correspondingly small and compact, with the secondary heat exchanger in particular not only being simple and rational producible, but should also be easy to integrate into the boiler or the boiler housing with a high concentration and optimal flowability of the heat transfer surface.

This object is achieved with a gas boiler according to claim 1. Advantageous further developments result from the subclaims.

Spirally wound heat exchangers are known per se, for example according to DE-A-925 721. With regard to the further state of the art known in this regard, reference is made to the following publications:
US-A-2 085 256, DE-A-95 873, DE-A-288 039, DE-A-101 612 and DE-A-1 753 342. Such helically wound heat exchangers are so inexpensive in terms of flow, their compactness and Surprisingly, even the heat exchanger may be found that such heat exchangers, as far as is known, have not been introduced as secondary heat exchangers integrated in the boiler housing, presumably because it is extremely difficult to keep the plates involved while maintaining their necessary distance from one another, ie without being able to wind spiral deformation at all.

The applicability of such spirally wound heat exchangers for boilers thus stands and falls in consideration of the necessary and largely mechanical series production with a training that permits uncomplicated production. Such a secondary heat exchanger is now available, however, and thus represents an essential element in combination with the other features for solving the task, which is assigned to the boiler where it is simplest, namely in the uncooled, i.e. non-water-bearing flue gas collection chamber, namely directly behind the combustion chamber opening, the opening cross-section and shape of which essentially corresponds to the total cross-sectional area, ie that of the spirally wound pocket and the flow cross-section for the heating gases. As a result, what will be shown on the basis of example representations, results in a very compact small boiler with an output in the order of magnitude of, for example, 12 KW, which can also be easily installed on a wall due to its small dimensions.

Advantageous embodiments of the boiler according to the invention consist of the following:
The exhaust gas collection chamber equipped with the secondary heat exchanger is sealed and releasably assigned to the water-carrying housing, the connection between the housing and the exhaust gas collection chamber being established by means of turnbuckles. As a result, the flue gas collection chamber with the built-in "plane spiral" can be easily replaced if necessary, should this be necessary, and when the flue gas collection chamber is removed, the combustion chamber interior is also easily accessible for inspection.

However, it is also possible to manufacture the exhaust gas collection chamber with the plane spiral as a separate structural unit without a detachable connection, i.e. the exhaust gas collection chamber is simply welded to the water-bearing housing.

There are various options for the function of the secondary heat exchanger in the form of a plane spiral. For example, the outflow connection of the secondary heat exchanger can be connected to the water-carrying interior of the housing, the heating return being connected to the inside of the plane spiral. The spiral coil serves as an additional heating surface for heating the heating water. In the same sense, however, it is also possible to use the plane spiral as a instantaneous water heater. The secondary heat exchanger can, however, also be formed from two pockets through which one can flow independently of one another, one of which is connected to the water-carrying interior of the housing and the other of which is connected to process water supply -discharge connections is provided, the two pockets being arranged one behind the other in relation to the axial gas flow direction.

However, it is also possible to design the secondary heat exchanger connected to the water-bearing interior of the housing to be double-stranded and to arrange a third strand with the hot water supply and drain connections between these two strands, which are in flat thermal conduction on both sides. In this case, the heat transfer to the process water does not take place directly through the heating gases, but indirectly through the heating water which flows through the strands adjacent to the process water line on both sides. A further embodiment in this regard, in which not even an additional pocket is required for the passage of the process water, is explained in more detail.

An embodiment is preferred in such a way that the exhaust gas collection chamber is arranged under the water-carrying housing, which is formed with the combustion chamber in the form of an elbow or arc piece and the burner is arranged with its axis oriented perpendicular or inclined to the winding axis of the secondary heat exchanger (s). The formation of water-carrying housings with the associated combustion chamber in the form of an elbow or elbow is known per se, but is of particular importance in the present context, since this further increases the compactness of the entire boiler and places the burner relatively close to the plane spiral leaves. The burner used here is not a flat gas burner (radiation burner), but one that is preferably used, the effective burner surface of which has, for example, a hemisphere or ellipsoid shape, i.e. a burner that not only against the water-cooled walls of the housing, but also directly against the spiral that forms the secondary heat exchanger takes effect.

The gas boiler according to the invention and further details are explained in more detail below with the aid of exemplary embodiments.

Fig. 1

einen Längsschnitt durch den Gasheizkessel in bevorzugter Ausführungsform;

Fig. 2

einen Querschnitt durch den Gasheizkessel längs Linie II-II in Fig. 1;

Fig. 3

einen der Fig. 1 entsprechenden Längsschnitt durch den Gasheizkessel mit zwei übereinander angeordneten Nachschaltwärmetauschern;

Fig. 4-6

im Schnitt entsprechend Fig. 1 andere Gestaltungsformen des wasserführenden Gehäuses;

Fig. 7

einen Schnitt durch den Gasheizkessel mit einem atmosphärischen Brenner;

Fig. 8

eine perspektivische Detaildarstellung der Planspirale;

Fig. 9

einen Schnitt durch eine besondere Ausführungsform der Planspirale mit Brauchwasserführung;

Fig. 10

einen Schnitt durch die bevorzugte Ausführungsform der Planspirale mit Brauchwasserführung;

Fig. 11

in Draufsicht eine besondere bauliche Einzelheit und

Fig. 12 A-E

verschiedene Ausführungsformen der Einzelheit nach Fig. 11.

It shows

Fig. 1

a longitudinal section through the gas boiler in a preferred embodiment;

Fig. 2

a cross section through the gas boiler along line II-II in Fig. 1;

Fig. 3

a longitudinal section corresponding to Figure 1 through the gas boiler with two superposed secondary heat exchangers.

Fig. 4-6

in section corresponding to Figure 1 other forms of water-bearing housing.

Fig. 7

a section through the gas boiler with an atmospheric burner;

Fig. 8

a detailed perspective view of the plane spiral;

Fig. 9

a section through a special embodiment of the plane spiral with hot water supply;

Fig. 10

a section through the preferred embodiment of the plane spiral with hot water supply;

Fig. 11

in plan view a special structural detail and

Fig. 12 AE

different embodiments of the detail according to FIG. 11.

The gas boiler basically and in a known manner consists of a water-carrying housing 1 in which a combustion chamber 3 equipped with a burner 2 and between this and the exhaust connection piece 4 of an exhaust gas collection chamber 5 one of the Post-flow heat exchanger NT through which heat can flow is arranged with inflow and outflow connections 6, 7 for the medium to be heated.

For such a gas boiler, it is now essential that the at least one post-heat exchanger NT is designed in the form of a pocket 9 which is axially gas-flowable and spirally wound between two parallel planes E and whose cross-sectional width B is substantially larger in cross-sectional main axis HA parallel to the winding axis WA and the secondary heat exchanger NT arranged in the uncooled exhaust gas collection chamber 5 and this is assigned to the water-carrying housing 1 as a separate structural unit, the total cross section of the secondary heat exchanger NT flowed by the heat-supply medium essentially corresponding to the opening cross section 8 of the combustion chamber 3 which is open to the secondary heat exchanger NT and circular in cross section.

1 shows the preferred embodiment in which the exhaust gas collecting chamber 5 is releasably and releasably associated with the water-carrying housing 1 with the interposition of an annular seal 18, the two parts being held together by turnbuckles 16.

In this embodiment, the plane spiral or the pocket 9 wound into a spiral in the sense of FIG. 2 serves as NT for passing the heating return, which is connected to the inflow connection 6 and after passage of the plane spiral from the center through a line piece 17 into the Interior 10 of the housing 1 arrives and heats it out through the outflow connection 7 (flow). If the planned spiral is to be used for the preparation of process water, the inflow connection 6 is the cold water connection, and the outflow connection 7 sits instead of the line section 17 directly on the planned spiral and serves as a hot water discharge connection from which the hot water can either be tapped directly or via a process water buffer store (not shown) .

The same construction principle is shown in the other exemplary embodiments according to FIGS. 3 to 6, in which corresponding elements are included corresponding reference numerals are provided. Here, however, the exhaust gas collection chambers 5, which are recognizable as separate structural units, are shown welded directly to the respective water-carrying housing 1, which makes an outer pipe section 17 unnecessary, since, as indicated by arrows, a direct connection between the spiral plane and the water-carrying interior space 10 can be established here.

An embodiment such that the post-heat exchanger NT is formed from two pockets 9, 9 'through which air can flow independently of one another, one of which is connected to the water-carrying interior 10 of the housing 1 and the other 9' with process water supply and discharge connections 6 ', 7 ', the two pockets 9, 9' being arranged one behind the other in relation to the axial gas flow direction, is illustrated in FIG. 3. As shown by arrows, the lower pocket 9 is used for heating the returning heating water and the upper pocket 9 'for that of the process water.

A special embodiment of the plane spiral is shown in section in FIG. 9. Thereafter, the secondary heat exchanger NT, which is connected to the water-carrying interior 10 of the housing 1, is double-stranded and between these two strands 11, which is in flat thermal contact on both sides, is a third strand 12 arranged with the hot water supply and discharge connections 6 ', 7'. All three strands 11, 12 are wound together into a spiral. The heat transfer to the process water or the process water-carrying pocket does not take place directly through the heating gas, but rather through heat-conducting contact of the pockets 9 lying flat on both sides of the pocket 9 '. In this embodiment, it is also possible to separate the strands 11, 12 separately wrap and insert the strand 11 in a spiral shape between the rods 12, which are also already in a spiral shape, for which the strands 11 below may not have any beads, as shown.

In all of the exemplary embodiments except for that of FIG. 6, which represents an atmospheric gas heating boiler, the water-carrying housing 1 is, as it were, saddled onto the exhaust gas collection chamber 5 containing the plane spiral or plane spirals, ie, the Exhaust gas collecting chamber 5 is arranged under the water-carrying housing 1, which is formed with the combustion chamber 3 in the form of an angle or arc piece 13, 13 'and the burner 2 is arranged with its axis 14 oriented perpendicular or inclined to the winding axis 15 of the post-heat exchanger NT. As burners, those with the shapes shown are used, the effective burner surface of which consists of metal mesh. In this way, the burner acts with its heat radiation not only directly against the water-cooled walls of the housing 1, but also against the spiral, and the boiler has small height dimensions. With a capacity for 7 to 12 KW, for example, the boilers shown in FIGS. 1 to 5 are only twice as large as shown.

With regard to the plane spiral forming the post-heat exchanger NT itself, reference is made to FIG. 8, according to which the inner wall 20, which is bent at the top and bottom with respect to the winding axis 15, has edges 22 corresponding to the width B of the water-carrying interior space 21 . The outer wall 23 has inwardly bent edges 24 with a maximum half width B, which edges 24 overlap the edges 22 of the inner wall 20 or are flush with them and are connected to them in a liquid-tight manner. Wave embossments 27 of both walls 20, 23 pointing into the gas-carrying interior 25 ', which is open on the inflow and outflow sides, are arranged and designed to be mutually supportive, at a distance D from the edges 22, 24 in the walls 20, 23, essentially parallel to the winding axis 15, and the water-carrying interior 25 is closed at both ends of the plane spiral except for the attached supply and return connection openings. Such a NT is shown in plan view according to FIG. 2, from which it can also be seen that the inner winding end of the spiral naturally does not begin in the center of the spiral, but on a filler body 26, which can also be designed as a hollow body and forms the return connection . A winding from the center is not allowed because the bending radii would be too small. In the illustrated embodiment according to FIG. 8, it is an NT with a relatively large height H, and in consideration of this, the inner wall 20 is provided with a central wave embossing 27 extending perpendicular to the winding axis 15, the depth of which corresponds to the width B of the water-carrying Interior 25 corresponds. This wave embossing 27 supports the wall 23 in the middle and divides the water-bearing interior 25, so that it flows through the filler body 26 (return connection) from in two corresponding spiral parallel flows and passes from the two openings into the water-bearing interior 10 of the boiler. The heating gases entering the NT from the combustion chamber 3 of the boiler flow through the gas-carrying interior 25 ', which is open on both sides, parallel to the winding axis 15. This configuration of the pocket 9 allows it to be continuously wound and welded, and is then surrounded with an adapted cladding sheet 19 and thus inserted into the exhaust gas collection chamber 5, the cladding sheet 19 (see FIGS. 1 to 6) advantageously facilitating installation in the exhaust gas collection chamber 5. The design and manufacture of the flat spirals are always the same, regardless of whether the flat spiral is used to pass heating water or process water.

If the NT is also to be used for heating domestic water, as already described for FIG. 9, this consists in a preferred embodiment according to FIG. 10 in that the spirally wound pocket 9 is formed from two pocket parts 9 ', with their mutually facing flanks 28 delimit a service water channel 29, the two pocket parts 9 'in cross-sectional profile being of identical shape except for the upstream and downstream closing edges 30.

The flanks 28 of the two pocket parts 9 'delimiting the process water channel 29 are, as shown, provided at their edges with mutually directed and welded upper and lower closures of the process water channel 29 forming bead embossments 31. A weld seam made of additional welding material (not shown) is laid in the gusset 31 ′ thereby given.

Furthermore, in this exemplary embodiment, the gas-charged flanks F of the two pocket parts 9 'are provided with groove impressions 32 extending in the winding direction, with profile-matched spacer wires 33 being arranged between the groove impressions 32 of the adjacent flank F.

The groove embossments 32 have a much smaller depth than the wave embossments 27 of the gas-charged flanks F, because otherwise the heating gas passage would be prevented. Since the wave embossings 27 have a relatively small height of only 3 to 4 mm with a sheet thickness of about 0.8 to 1 mm, the gas passage cross section of the entire spiral would be too small in this compact design, ie that one could in this way by the arrangement of the Spacer wires, without having to increase the height of the wave embossments, would have to increase the gas passage cross section accordingly. Apart from that, the spacer wires lead to an improved gas swirl.

As already described for FIG. 8 and at a height H of the pocket 9 or the pocket parts 9 'of approximately 110 to 130 mm, the flanks WF of the two pocket parts 9' on the winding axis side are in each case centered and with one to the adjacent one water-side wall W recessed and extending in the winding direction support embossing.

The closure edges 30 are, as shown, formed, that is, they are provided with short, outwardly directed bends 31 '' which, after the walls involved have been brought together during winding, are simply melted down without filler material, thereby avoiding exposed protruding connecting edges would be particularly disadvantageous on the gas inflow side. This embodiment is also preferred in all of the other embodiments of the NT described above.

In order to be able to use the above-described gas boiler as a condensing boiler or to set a specific exhaust gas temperature without having to make any essential changes, 19 gas outlet openings 40 are arranged on the cladding sheet metal, to which at least one adjustable closing screen 41 is assigned on the outside of the cladding sheet metal 19, "at least one "includes the basic possibility of equipping each of the gas outflow openings 40 with a separate closing panel, which would, however, involve considerable effort. Otherwise, the gas outflow openings 40 can also be arranged along at least two circumferential surface lines 42, which is not particularly shown, since it is readily conceivable.

An embodiment according to FIG. 12B is preferred in which the closing panel 41 is designed in the form of a ring 44 which can be adjusted parallel to the sheathing plate axis 43. The same also applies to the special embodiment according to FIG. 12 E, in which the gas outflow openings 40 are formed as slots 45 that are parallel to the axis of the sheathing plate 43 and the annular closing diaphragm 41 that is adjustable on the axis of the sheathing plate 19 has a width B that corresponds to the length L of the slots 45 .

The directions of displacement or adjustment of the closing panels are indicated by arrows P. The embodiment according to FIG. 12 E has the peculiarity that, apart from total closure (shown) or opening of the slots 45, depending on whether the closing panel 41 (indicated by dashed lines) is moved up or down, exhaust gas from the peripheral flow gap 46 can flow further up or down from the envelope 19 directly into the exhaust gas collection chamber. This axially parallel displaceability of the closing panel takes into account the simplest of all the shape of the cladding sheet 19 illustrated in FIG. 11, which results from the spiral shape of the pocket forming the plane spiral.

Apart from this, it is also possible according to FIG. 12 C to design the closing diaphragm 41 in the form of a ring 44 ″ rotatable about the cladding sheet 19 and to provide the latter with the gas outflow openings 40 of the cladding sheet 19 in the form and arrangement of corresponding through-flow openings 40 ′. The step 19 '(see FIG. 11) on the cladding sheet 19 does not constitute an obstacle to rotation since, for example, the ring 44' 'can also be designed as a radially expandable sleeve and adjusted, and then tightened again.

In order to ensure that the respective closing panel maintains its position in the event of changing temperature loads, it is provided with at least one fixing element 47, for which, for example, a simple small self-tapping screw is sufficient.

Claims (14)

1. A gas boiler comprising a water-carrying casing (1) in which is arranged a combustion chamber (3) furnished with a burner (2), and in which is disposed between the combustion chamber (3) and the discharge connecting nozzle (4) of an exhaust gas collecting chamber (5) at least one add-on heat exchanger (NT) flown-through by heat-exchanging fluids and including in-flow and off-flow connections (6,7) for the fluid to be heated, wherein the add-on heat exchanger (NT) is in the form of a pocket (9) through which gas is axially flowable and which is helically wound about a winding axis (15) between two parallel planes (E), with the main axis (HA) of the said pocket (9) having a cross-section by a multiple larger than the cross-sectional width (B) thereof being directed in parallel to the winding axis (15),
   wherein the add-on heat exchanger (NT) is arranged within the non-cooled exhaust gas collecting chamber (5), with the latter being associated as a separate unit to the water-carrying casing (1), and wherein the entire cross-section of the add-on heat exchanger (NT) in-flown by the heat supplying fluid substantially corresponds to the cross-section (8) of the opening of the combustion chamber (3) open toward the add-on heat exchanger (NT) and circular in cross-section.
2. A boiler according to claim 1,
   characterized in that the exhaust gas collecting chamber (5) furnished with the add-on heat exchanger (NT) is sealingly and detachably associated to the housing.
3. A boiler according to claims 1 or 2,
   characterized in that the off-flow connection (7) of the add-on heat exchanger (NT) is connected to the water-carrying interior (10) of the casing (1).
4. A boiler according to any one of claims 1 to 3,
   characterized in that the add-on heat exchanger (NT) is formed of two independently flown-through pockets (9,9'), one of said pockets being in communication with the water-carrying interior (10) of the casing (1) and the other pocket (9') being provided with process water supply and discharge connections (6',7').
5. A boiler according to claim 4,
   characterized in that the add-on heat exchanger (NT) in communication with the water-carrying interior (10) of the casing (1) is of a dual-line design and that provided between these two lines (11) is a third line (12) including process water supply and discharge connections (6',7') and being, on both sides, in planar heat conducting contact with lines (12).
6. A boiler according to any one of claims 1 to 3,
   characterized in that the helically wound pocket (9) is formed of two pocket parts (9') confining with their oppositely directed flanks (28) a process water channel (29).
7. A boiler according to claim 8,
   characterized in that the two pocket parts (9') in their cross-sectional profile are of an identical shape except for the closure edges (30) on the in-flow and off-flow sides.
8. A boiler according to claim 7,
   characterized in that the flanks (28) of the two pocket parts (9') confining the process water channel (29) at the edges thereof are provided with oppositely directed welded-together beads (31) forming top and bottom closures of the process water channel (29).
9. A boiler according to any one of claims 6 to 8,
   characterized in that the flanks (F) of the two pocket parts (9'), to which gas is applied, are provided with grooves (32) extending in the winding direction, and that spacer wires (33) of conforming profiles are provided between the grooves (32) of the neighbouring flanks (F).
10. A boiler according to any one of claims 1 to 9,
    characterized in that the exhaust gas collecting chamber (5) is disposed underneath the water-carrying casing (1) which with the combustion chamber (3) is in the form of an angular or arcuate section (13,13'), and that the burner (2) with the axis (14) thereof is arranged in a direction vertical or at an inclination to the winding axis (15) of the add-on heat exchanger(s) (NT).
11. A boiler according to any one of claims 1 to 10,
    characterized in that at least one helically wound add-on heat exchanger (NT) is arranged within a cover sheet (19) and is inserted therewith in the exhaust gas collecting chamber (5).
12. A boiler according to claim 11,
    characterized in that a plurality of gas off-flow openings (40) are peripherally provided on the cover sheet (19) along at least one of the central circumferential elements (42), and that associated to the said gas off-flow openings (40), at the outer side of the cover sheet (19), is at least one adjustable closure orifice (41).
13. A boiler according to any one of claims 1 to 12,
    characterized in that the burner (2) arranged within the combustion chamber (3) as a radiation burner is of a spherical shape, and that a part (F) of the burner face is arranged above the in-flow cross-section of the add-on heat exchanger (NT).
14. A boiler according to any one of claims 4,5 and 10 to 13, characterized in that the heating water-carrying pocket(s) is/are formed of light sheet metal, such as aluminium sheet metal, while the process water-carrying pocket(s) is/ are formed of high-grade steel sheet metal.

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