DE1751347A1 - Extruded hollow profiles without longitudinal weld seams on the pressure-carrying cross-sections for the production of tightly welded heating or cooling surfaces - Google Patents

Description

The invention relates to extruded hollow profiles without longitudinal welds on the pressure-carrying cross-sections for the production of tightly welded heating or cooling surfaces with smooth outer walls.

Round and rectangular tubes are known which are welded together with and without fins or webs to form gas-tight surfaces. The pipe wall surfaces made from round pipes have a corrugated surface transversely to the longitudinal axes of the pipes and are therefore unfavorable in terms of flow for the external medium, or they result in erosion in dusty media or contamination in the case of adhering media. Pipes of square or rectangular cross-section are not completely sharp-edged for reasons of uniform wall thickness and strength, but also with a small rounding, so that even with the heating surfaces made from these pipes a slightly corrugated surface cannot be avoided. In addition, because of their strength at high pressures, rectangular tubes are either unsuitable or have too great a wall thickness.

It is also known to use round containers for heat transfer purposes or cylindrical elements, e.g. B. for cooling burner mouths, welded together from round or rectangular extruded profile tubes.

Extruded tubes with fins attached to one side are also known, from which tube walls are made with a smooth and a corrugated surface.

Furthermore, tubular profiles are known which have a circular cross-section on the inside and a semicircular cross-section next to them, so that whole circular cross-sections are created when they are welded together. These profiles have the disadvantage, especially for the production of burner mouths, that an open semicircle remains at the end, which must be removed and, moreover, two longitudinal welds are present on every second pressure-carrying circular cross-section.

The object of the present invention is to create an extruded hollow profile for the production of tightly welded heating / or cooling surfaces, which forms smooth outer walls, does not require high-pressure-tight longitudinal welds and has no essential webs or return lines at the end of a heating surface.

To solve this problem, a profile is proposed which is circular on the inside, flat on the outside on two opposite parallel sides, the ends of which are beveled, and which is delimited by convex circular arcs between the two parallel flat surfaces. (Fig. 1)

According to a second preferred form of the invention, a flat or slightly twisted web is used in the circular cross-section, so that two separate channels are formed in the tube, z. B. can be used for the outward and return flow of the heat transfer medium. (Fig. 2). In the case of flat webs, it can be useful to provide the hollow profile with two opposing grooves corresponding to the web size on the inside. With regard to the later curvature of the hollow profile, it is expedient to arrange the flat web parallel to the flat outer surfaces of the pipe. Because of the reduction in wall thickness due to the longitudinal groove, it is better to arrange the webs diagonally, while for reasons of better temperature compensation, cases are also conceivable where the e- bene web is arranged perpendicular to the flat outer surfaces of the hollow profile.

According to a third preferred form of the invention, an inner, smaller tube is inserted into the outer tube and spaced with several webs on the circumference against the inner wall of the large tube, so that two separate channels for inlet and return are also created. These pipes can expediently be closed with a spherical base and thus enable a diversion from the outward to the return. (Fig. 3).

According to a further concept of the invention, heating or cooling surfaces are wound from the proposed profile tubes and welded to one another in a gas-tight manner. Either two or more pipes, each containing only one channel, are wound and welded together and connected at the end with a deflection bend, so that the heat-transferring medium runs back and forth in one pipe, or it becomes just one pipe, but that contains two channels, wound together to form a heating surface and welded, then the heat-transferring medium flows in one channel, back in the other and is deflected at the end of the tube in a spherical base.

Possible embodiments of the invention are described below with reference to several figures:

Figure 1 shows a hollow profile without internals.

Figure 2 shows a hollow profile with a web that divides the profile into two channels.

FIG. 3 shows a hollow profile with an inner tube spaced apart by webs.

Figures 4 to 13 show possible applications of the proposed hollow profiles.

FIG. 4 shows the cooling system of a pulverized coal burner. This consists of an inner cooling jacket
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which is concentrically enclosed by two further cooling jackets 2 and 3. The inner cooling jacket 1 guides the core air, the dust-laden carrier air flow flows between the jackets 1 and 2 and the jackets 2 and 3 enclose the secondary air flow.

FIG. 5 shows a cooling jacket made from a double spiral, FIG. 6 shows the detail of the end of the double spiral facing the combustion chamber, and FIG. 7 shows a section III-III through FIG. 6.

A cooling jacket made from a simple spiral is shown schematically in FIG. FIG. 9 shows as a detail the end of the winding facing the combustion chamber, while FIG. 10 shows a section VI-VI through FIG.

FIG. 11 again shows a cooling jacket as described in FIG. 8, FIG. 12 the associated pipe end, FIG. 13 the section IX-IX of FIG. 12.

The profile tube shown in Figure 1 is bent over one of the flat sides in the form of a cylindrical spring and welded together to form a cylinder, so that a cylinder with a smooth surface is obtained (possibly after grinding the welds 6).

Since the inlet and outlet of the coolant must be arranged on one and the same side, one pipe end 4 is led back along the outside of the cylinder in the case of single-thread helical windings (FIG. 4, items 1 to 3). This can be avoided if the cooling jacket is wound from a two-flight spiral (FIG. 5) and a deflection cap 5 is welded to the end of the cylinder facing the combustion chamber, as shown in FIG.

Claims (5)

1.) Extruded hollow profiles without longitudinal welds on the pressure-carrying cross-sections for the production of gas-tight welded heating or cooling surfaces with smooth outer walls, characterized in that the hollow profile (Fig. 1) is circular on the inside, on the outside on two opposite sides, the ends of which are beveled, is bounded by parallel flat surfaces, while the profile between the two parallel flat surfaces consists of convex circular arcs. 2.) Extruded hollow profiles according to claim 1, characterized in that a flat or slightly twisted web (8) is used in the clear circular cross-section (Fig. 2), which divides the pipe cross-section into two separate channels. 3.) Extruded heat exchanger tubes according to claim 1, characterized in that in the clear circular cross-section (Fig. 3) an inner smaller tube (9) is used, which with several webs (10) on the circumference against the inner wall of the outer tube res is distant and thus forms two separate channels. 4.) heating or cooling surfaces made of two helically wound, gas-tight welded together extruded hollow profiles according to claim 1, characterized in that the heat transfer medium in one hollow profile runs back in the other and is deflected at the end of the two hollow profiles by a semicircular deflector (5) will. 5.) heating or cooling surfaces made of a gas-tight, helically wound welded extruded hollow profile according to claim 2 and 3, characterized in that the heat-transferring medium in one of the two separate channels of the hollow profile runs back in the other and at the end of the tube in a spherical base ( 7) is diverted.