US20120055420A1

US20120055420A1 - Sectional boiler

Info

Publication number: US20120055420A1
Application number: US13/318,308
Authority: US
Inventors: Gerhard Jung; Holger Henrich; Rainer Rausch
Original assignee: Individual
Current assignee: Robert Bosch GmbH
Priority date: 2009-06-05
Filing date: 2010-05-31
Publication date: 2012-03-08
Also published as: EP2438382A2; WO2010139662A2; DE102009024070A1; EP2438382B1; WO2010139662A3

Abstract

A sectional boiler is described as being made of cast iron or aluminum, in particular a condensing boiler, having essentially annular sections, a front section, a cover-shaped rear section and at least one center section being provided, which form a combustion chamber having an essentially surrounding heat exchanger made of a sectional block, whose annular water chambers are connected to one another via at least one hub and which has gap-like heating gas flues, having a return port and a feed port in the upper area and at least two armature rods for holding the sectional block together. The present system is based on the objective of optimizing a sectional boiler made of cast iron or aluminum particularly with respect to compactness and robustness. In the present system, as heating gas flues the heat exchanger respectively has annular gaps between two adjacent sections having a mutually adapted geometry, which respectively run from the combustion chamber approximately radially outward and open into an exhaust gas collection chamber on the outside of the sections, and the individual sections are respectively divided on the heating water side into at least two flow channels.

Description

FIELD OF THE INVENTION

The present invention relates to a sectional boiler, in particular a condensing boiler made of cast iron or aluminum materials.

BACKGROUND INFORMATION

Sectional boilers of this kind are made up of multiple boiler sections cast in one piece, which are arranged one behind the other and are connected to one another on the water side by hubs. A flow is thus created through the water channels and water pockets formed by the boiler sections between the return port and the feed port. Normally, generic sectional boilers have a lower return port and a feed port situated on top, which may be in the respective hub. The heating gases flow from the combustion chamber via downstream heating gas flues to an exhaust gas connection and on their way give off heat to the boiler water.
In all existing boilers of this kind, the sections are arranged in series one behind the other. There is an annular front section, on which a combustion chamber door or a burner plate may be fastened, one or multiple similarly designed center sections depending on the performance capacity, as well as one rear section. The combustion chamber extends through the front and center sections to the rear section, which forms the'bottom of the combustion chamber with its cover-shaped design. In these specific embodiments, all boiler sections have similar outer dimensions because they form parts of the combustion chamber, heating gas flues and water chamber over the entire cross section of the boiler. Furthermore, boilers for low performance ranges are also known, which are made up of only two or even merely one boiler section.
With respect to the exhaust gas guidance and the efficiency of the heaters, one distinguishes between conventional heating technology and condensing heating technology. For reasons of saving energy, condensing heaters are increasingly used. The construction of their heat exchanger allows for the possibility of cooling the humid exhaust gases, which are produced when burning fuel and air in operation, to below the exhaust gas dew point. The humidity of the exhaust gases condenses out in the process, and, in addition to the sensible heat, the condensation heat is transmitted to the heating water.
In a use as a condensing boiler, particular value must be set on the selection of material, for based on the composition of the utilized fuel and the combustion control, the exhaust gases are contaminated with pollutants, and the produced condensed water contains different acids in low concentration. The components touched by the condensed water such as heating surfaces, exhaust gas collector and exhaust gas line must therefore be resistant to the acids, which is why it is customary to manufacture these components from stainless steel, aluminum or plastic. Welded stainless steel heat exchangers are generally used especially in oil condensing heating technology, as discussed, for example, also in DE 10 2004 023 711 B3 as a spiral pipe winding. They offer the advantage of bearing the acid contamination without corrosion. Disadvantages are the high costs associated with the material as well as the less favorable scaling conditions especially in welded constructions of sheet metal, and the greater sizes, which are difficult to assemble in tight spatial conditions.
The heat exchangers of conventional heaters are often made of cast iron. They are characterized by high robustness and a long lifespan. Their construction from mostly identical cast segments allows for a cost-effective manufacture and easy scalability with respect to varying performance capacities and offers good assembly options even under tight set-up conditions. The material withstands very well the brief exhaust gas condensation phases at the start of operation and when the heat exchanger is cold. In today's form and design, cast iron is not suitable for condensing heating operation, however, where condensed water is produced for a longer period.
Furthermore, a condensing boiler having an integrated compact heat exchanger made of a corrosion-resistant material, which is hydraulically connected downstream, is discussed in DE 296 21 817 U1. As a separate component, this compact heat exchanger is enclosed by two shell-shaped boiler sections and is connected separately on the water side. All boilers having a heat exchanger connected downstream have the disadvantages of increasing the assembly efforts because of the required pipe pieces and of raising the resistance on the water side. The positioning as a separate exterior component also results in cooling losses, which must be reduced by a suitable thermal barrier.
German patent document DE 44 25 302 C2 discusses positioning the feed port and return port in a common upper boiler hub. For this purpose, a mixing zone is formed in the upper region of a common water chamber such that the incoming cold return water is preheated by the rising hot feed water. This prevents condensation in the area of the heating surfaces.

SUMMARY OF THE INVENTION

The exemplary embodiments and/or exemplary methods of the present invention are based on the objective of optimizing a sectional boiler made of cast iron or aluminum particularly with respect to compactness and robustness.
According to the exemplary embodiments and/or exemplary methods of the present invention, this objective is attained by the features described herein. Advantageous developments may be derived from the further descriptions herein.
The sectional boiler is characterized by the fact that the heat exchanger has as heating gas flues respectively annular gaps between two adjacent sections having a mutually adapted geometry. Starting respectively from the combustion chamber, these run approximately radially outward and empty into an exhaust gas collection chamber on the outside of the sections.
Various specific embodiments are possible for this purpose, for example that in the first instance an annular gap runs at a right angle with respect to the center axis of the combustion chamber radially and in a straight line outward. In a second variant, an annular gap is radially curved and runs outward in an arched manner similar to a turbine blade geometry. A third specific embodiment provides for an annular gap having a tilted position with respect to the center axis of the combustion chamber to run in a straight line outward. This is particularly suitable in an upright arrangement of the entire sectional block because the condensate is then able to run off particularly well all around from a gap downward. Furthermore, an annular gap may also run in the radial direction in wavelike fashion outward, in particular in order increase the flow turbulence within a gap so as to achieve an intensive heat transfer on the surfaces.
Advantageously, the width and/or the free cross section of an annular gap decreases from the combustion chamber to the opening on the outside of the sections in order to achieve an adaptation to the heating gas volume that decreases with cooling. The surfaces of the sections touched by the heating gas, at least the surfaces forming the gap, may be provided with a corrosion protection coating.
The exhaust gas collection chamber on the outside of the sections, into which the annular gaps empty, extends as a hollow cylinder around the outer jacket surfaces of the sections and is bounded outwardly by a jacket. The latter is accommodated in sealing fashion between annular webs radially projecting outward on the outside of the front section and the rear section.
The individual sections are respectively divided on the heating water side into at least two flow channels. For this purpose, each section has on the heating water side at least one separating wall and is thereby divided into an inner flow channel near the combustion chamber and at least one outer flow channel of a larger diameter. In the area of the lower hub, the at least two flow channels in a section are hydraulically connected to each other by an overflow opening in the separating wall such that the flow passes through these in series. Starting from the upper return port, the return water first reaches the bottom in both halves of a section in the respectively outer flow channel of the greater diameter, flows inward on the overflow opening and then in both halves of a section reaches again the feed port on top respectively in the inner flow channel near the combustion chamber.
In a first specific embodiment, the inner flow channel near the combustion chamber has a smaller cross section than the outer flow channel away from the combustion chamber. In another specific embodiment, the inner flow channel near the combustion chamber is dimensioned in such a way that higher flow speeds set in than in the outer flow channel far from the combustion chamber.
Advantageously, the return port is situated in the area of the upper hub above the feed port, and a feed pipe is provided for return water. At the level of the section, it respectively has at least one opening for feeding return war into the outer flow channel of each section that is far from the combustion chamber.
The sectional block may be held together by a feed-in pipe for return water, a withdrawal pipe for feed water and/or a conventional armature rod situated within the hubs. If the water-conducting pipes are used, then these are to be fitted with the appropriate threads for bracing the set-up.
The feed port is situated in the area of the upper hub below the return port, openings being provided between the individual sections, which are aligned with one another in the longitudinal direction, and which act as a connection between the respective inner flow channels near the combustion chamber.
The individual sections are sealed with respect to each other in the area of the lower hub, a closing and/or sealing arrangement being attached on an armature rod situated within the hub, or are inserted into the connecting points in a known manner, for example in the form of sealing rings.
The exemplary embodiments and/or exemplary methods of the present invention provides a sectional boiler with the best suitability for condensing heating operation, in which the positive material properties of cast iron or aluminum are specifically applied and utilized in order to ensure good heat transfer properties, compactness and robustness. Operating states and loads that trigger corrosion are minimized by the water guidance according to the exemplary embodiments and/or exemplary methods of the present invention. Dividing the flow channels optimizes the temperature distribution in the heat exchanger and increases the effectiveness with respect to known principles.
According to the exemplary embodiments and/or exemplary methods of the present invention, it is also not only easy to apply and check a corrosion protection coating, but the latter is also protected in the gaps against possible mechanical stresses. In addition to the simple manufacture, the sectional construction also offers the advantage of allowing for different lengths for various heating and heat exchanger performances in a variable manner by inserting additional center sections. All water-side connections, for example, are located for easy access on one side in the upper region. Nevertheless, all front-side attachment parts as well as the water-side connections remain the same. Only the surrounding jacket around the exhaust gas collection chamber varies. Due to the low exhaust gas temperatures, the latter may even be manufactured from plastic.
The drawings represents an exemplary embodiment of the present invention. It shows a sectional boiler made of cast iron or aluminum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional boiler made of cast iron or aluminum in a perspective overall view with a vertical section.

FIG. 2 shows a sectional boiler made of cast iron or aluminum in a vertical cross section through one half of a section.

DETAILED DESCRIPTION

The sectional boiler is essentially made up of annular sections, namely, a front section 1, a cover-shaped rear section 2 and multiple center sections 3. These form a combustion chamber 4 and respectively have annular water chambers. They are connected to one another via an upper and lower hub 5, 5′.
As heating gas flues, the heat exchanger formed by the sectional block has respectively annular gaps 6 between two adjacent sections 1, 2, 3 having a mutually adapted geometry, which, starting from combustion chamber 4, respectively run approximately radially outward and open into an exhaust gas collection chamber 7 having an exhaust gas connection 8 on the outside of the sections 1, 2, 3.
On the heating water side, the individual sections 1, 2, 3 are respectively divided into two flow channels 9, 10 and have respectively one separating wall 11 for this purpose. This produces an inner flow channel 9 near the combustion chamber and an outer flow channel 10 of a greater diameter, these being hydraulically connected to each other in a section 1, 2, 3 in the area of lower hub 5′ by an overflow opening 12 in separating wall 11 such that the flow passes through them in series. Beginning from upper return port R, the flow first separates into the two halves of a section 1, 2, 3. On both sides, the return water reaches the bottom in the respective outer flow channel 10 of the greater diameter, flows inward at overflow opening 12, and then rises again on both sides of combustion chamber 4 in inner flow channel 9 upward to feed port V.
Return port R is situated above feed port V in the area of upper hub 5. A feed-in pipe 13 is used for dosing the incoming return water respectively via one opening 14 directed laterally into outer flow channel 10 at section level. Feed-in pipe 13 is also used to hold together the sectional block in the area of upper hub 5. By contrast, an armature rod 15 is situated in lower hub 5′, which reaches through lower hub 5′ and also fixates a closing and/or sealing arrangement between individual sections 1, 2, 3.
Feed port V is situated in the area of upper hub 5 below return port R, openings 16 being provided between mutually aligned individual sections 1, 2, 3, which act as a connection between the respective inner flow channels 9 near the combustion chamber.

Claims

1-9. (canceled)

10. A sectional boiler made of one of cast iron and aluminum, which is a condensing boiler, comprising:

essentially annular sections, including:

a front section;

a cover-shaped rear section; and

at least one center section;

wherein the sections form a combustion chamber having an essentially surrounding heat exchanger made of a sectional block, whose annular water chambers are connected to one another via at least one hub and which has gap-like heating gas flues, having a return port and a feed port in the upper area and at least two armature rods for holding the sectional block together, and

wherein as heating gas flues the heat exchanger respectively has annular gaps between two adjacent sections having a mutually adapted geometry, which respectively run from the combustion chamber approximately radially outward and open into an exhaust gas collection chamber on the outside of the sections, and the individual sections are respectively divided on the heating water side into at least two flow channels.

11. The sectional boiler of claim 10, wherein each section has at least one separating wall on the heating water side and is thereby divided into at least one inner flow channel near the combustion chamber and at least one outer flow channel of a greater diameter.

12. The sectional boiler of claim 10, wherein the at least two flow channels in a section in the area of the lower hub are hydraulically connected to each other by an overflow opening in the separating wall so that the flow passes through them in series, initially in the two halves of a section, return water from the upper return port reaching the bottom in the respectively outer flow channel of a larger diameter, flowing inward at overflow opening, and then again reaching the feed port at the top in the two halves of a section, respectively in the inner flow channel near the combustion chamber.

13. The sectional boiler of claim 10, wherein the inner flow channel near the combustion chamber has a smaller cross section than the outer flow channel far from the combustion chamber.

14. The sectional boiler of claim 10, wherein the inner flow channel near the combustion chamber is dimensioned so that higher flow speeds set in than in the outer flow channel far from the combustion chamber.

15. The sectional boiler of claim 10, wherein the return port is situated in the area of the upper hub above the feed port, and a feed-in pipe for return water is provided, which respectively has at the level of the section at least one opening for feeding return water into the outer flow channel far from the combustion chamber of each section.

16. The sectional boiler of claim 10, wherein at least one of a feed-in pipe for return water, a withdrawal pipe for feed water, and an armature rod situated within the hubs is used for holding together the sectional block.

17. The sectional boiler of claim 10, wherein the feed port is situated in the area of upper hub below return port, mutually aligned openings being provided between the individual sections, which act as a connection between the respective inner flow channels near the combustion chamber.

18. The sectional boiler of claim 10, wherein in the area of the lower hub the individual sections are sealed with respect to one another, and wherein at least one of a closing arrangement and a sealing arrangement is attached on an armature rod situated within the hub.