Boiler for burning the liquid or gaseous fuels

The invention relates to a boiler for the combustion of liquid or gaseous fuels, in particular for smaller outputs, consisting of a water-flowing steel sheet casing in which a cylindrical chamber for receiving the combustion chamber is arranged and fuel gas channels with a pre-return chamber. surrounded by a plurality of flue gas ducts distributed over the entire circumference and arranged at a certain distance side by side, which are connected to the flue gas collection chamber with the flue gas exhaust.

Boilers of this kind are known from Swiss Patent Specification No. 485 182, particularly from German Patent Specification No. 1,778,880. These known boilers may meet the requirements for heat utilization, but practical implementation and economical production pose considerable problems for which It was also not possible to introduce such boilers on the market.

It is also of interest that embodiments of the subject-matter of the aforementioned patents are provided in which a U-shaped or approximately U-shaped sheet metal profiles are welded to the inner shell of the cylindrical shell and welded thereto along their edges. On the other hand, boilers of this kind cannot be operated without difficulty in large temperature ranges, in particular not in low temperature regions, for example 30 to 60 ° C, due to the corrosion risk associated with these low temperatures.

Although the idea of ​​such a design of fuel gas channels in boilers of this kind is good in itself, such boilers are not sufficient to meet the requirements of economically feasible and manageable production possibilities, the long service life required and, lastly, the optimum heat transfer ratios. and favorable corrosion behavior, bearing in mind that such boilers are to be designed for a smaller power range, of the order of 10 to 25,000 kcal / hbd., which are increasingly in demand today in terms of energy savings with improved thermal insulation of heated spaces, require a disproportionately high production cost, which cannot be compensated for by a somewhat reduced amount of material.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve heating boilers of the type known and described above in such a way that it is at least approximately optimal. To realize the above-mentioned requirements, i.e., a heating boiler is to be designed, especially for smaller outputs of the order of 10 to 25,000 kcal / h, which can be economically advantageously produced without difficulty, which functionally fulfills the requirements of heat transfer and coping with condensate produced during certain stages of operation, in operation and in low temperature areas.

This object is achieved by a heating boiler according to the invention in that the cylindrical chamber is made as a gray-cast body in gray cast iron, in areas critical to the presence of unconditioned condensate. Chip removal passing through the front and rear, rectangular or circularly cut walls steel sheet casings which are fluid-tightly connected to the gray cast iron body by their openings, on the inner surface of which the bridges are also co-formed in the combustion chamber region, directed radially inwards, carrying the combustion chamber sleeve and laterally restricting the gas passageways, said bridges extending at a maximum height over the surfaces of the return chamber and the flue gas collection chamber, preferably bridges laterally restricting the gas passageways, they are made at the same height as the bridges, which extend over the surfaces of the return chamber and the flue gas collection chamber.

In this solution according to the invention, therefore, both the favorable properties of the non-machined gray cast iron in terms of condensate attack behavior and the good workability of the steel sheet are combined, and the formation of channels for passage to the tern is included with the tern. gas and thus all welding work in this area is eliminated. In order to achieve good heat transfer ratios from only the retractable combustion chamber sleeve to the bridges, the bridges may advantageously be provided with narrow transverse bridges, which can be machined on the bearing surfaces without further removal by chipping for good bearing of the combustion chamber. since in these places the bridges never reach temperatures critical for condensate.

Since the bridges themselves are not water-cooled but water-cooled the wall of the cylindrical chamber from which they project together. For example, in the case of small cast bridges, these bridges are preferably provided with transverse slots in order to accommodate different temperature stresses.

In order to include a liquid-tight inclusion of the cylindrical chamber in the outer. sheet steel sheath is a chamber with. it is advantageously produced by being connected in fluid-tight manner to its outer end regions with steel plate rings, which are always cast in one annular collar of the chamber. Advantageously, these ducts, for example the front and rear walls of the housing, are also snapped on or stretched only on the outside machined surface of the annular collar of the chamber.

Also, in view of the different heat-related behavior, the rings can be provided with a circular thinning of the wall thickness. The rings, together with the chamber - if they do not form the front and rear walls themselves - are inserted into the corresponding holes in the front and rear walls of the boiler shell and welded thereto. With a view to the efficient insertion of the ring-enclosed chamber, the sides of the ring are milled with different outer diameters if the outer sheath is already made available. If the rings themselves form the front and rear walls of the outer shell, they only need to be surrounded and welded with a cylindrical sheet steel sleeve.

The heating boiler according to the invention is explained in more detail below with reference to the drawing, in which: FIG. 1 shows a longitudinal section through a heating boiler; FIG. 2 shows a partial section through a heating boiler according to FIG. 1 and 3 show a structural detail in section.

As can be seen from Fig. 1, the entire "inner boiler" only comes from the cylindrical chamber 1, cast. of gray cast iron, which are included with it cast and slotted 14. bridges 9, and thus. The gas passageways 8, which are radially outwardly restricted by the inner surfaces 5 and radially inwardly limited by an insertable sleeve 7 of the combustion chamber, for example made of stainless steel. Bridges. 9 are provided at their free ends 12 with narrow cross bridges 13, wherein. the transverse web surfaces 13 'are for the purpose of. of the combustion chamber sleeve 7 surrounding the combustion chamber 8 is machined. The deterioration of the casting crust, which is well resistant to the action of condensate, is not critical in this area, since the bridges are always heated to a temperature above 60 [deg.] C. The bridges 9 in the return chamber 10 and the flue gas collection chamber 11, on the other hand, remain untreated and only have a height of about 3 to 1 mm, are kept thinner than the bridges 9 and are safely warmer than the outer cooled peripheral walls in these chamber areas. By this arrangement of the bridges 9 ', the possible occurrence of condensate in the lower region is therefore reduced to a minimum.

The production of the cylindrical chamber 1 with bridges 9 in terms of the casting technique also makes it possible to determine differently the different heights of the bridges in such a way that the mounted sleeve 7 of the combustion chamber is eccentrically folded upwards. FIG. 2 is represented by a dashed line. There is also no difficulty in arranging in the lower regions. the return chambers 10 and the collecting chambers 11 have bridges 9 'at a smaller distance, whereby the heating gases are even more intensely held away from the walls in these cold places. Critical in itself. As shown in FIG. 1, the connection of the gray cast iron and the steel sheet is very simple. by making the rings 16 of steel. sheet, which preferably themselves form the front. and a rear wall 3, 4 of the boiler jacket. and they are in this. In this case, they are directly welded to the cylindrical outer sheet steel shell 21 and are embedded in annular collars. 17. at the outer end regions 15 of the chamber 1 or heat-sealed on the machined peripheral parts. the surfaces of the annular collars 17 (FIG. 3) for which they are. the edges of the 19 holes more or. less bent outwards, so that some kind of hot-flanges are formed. Due to the different thermal expansion of the gray cast iron and the steel sheet, the rings 16 are provided with a circularly thinning of the wall thickness.

If it must be at this. In the case of a heating boiler on a gray cast iron body 2, machining operations taking off the chips and destroying the casting crust, which are well resistant to the action of condensate, are carried out on these parts, which are non-critical in this respect.

How are you . 2, another preferred form. An embodiment consists in that the bridges 9 'in the return chamber 10 and the flue gas collection chamber 11 are arranged in both lower quadrants inclined downwards so that the condensate deposits run onto the free edges of the bridge tips, i. it is where the bridges are the hottest, which is safely achieved. condensate evaporates and prevents it from accumulating in the lower parts of the bridges. Bridges. 9 ”can be kept higher in height than shown in FIG.

The circular shape of the entire heating boiler, as shown in FIG. 1, is not necessary, i.e., the heating boiler can also be in terms of its own. the outer shape is also rectangular, but the chamber 1. and the gray cast iron body 2 remain cylindrical.