Heat exchange – Regenerator – Heat collector
Reexamination Certificate
1996-08-02
2001-07-03
Atkinson, Christopher (Department: 3743)
Heat exchange
Regenerator
Heat collector
C165S008000, C165S004000
Reexamination Certificate
active
06253833
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heating sheet bundle to be mounted tangentially or radially in trapezoidally segmented cells of heating surface carriers of regenerative heat exchangers with stationary or revolving storage masses. The sheet bundle is composed of a plurality of profiled sheets which are stacked on top of each other and are held together so as to form passage ducts therebetween.
2. Description of the Related Art
The regenerative heat exchanger can be used for the preheating of air as well as for the preheating of gas. When used as an air preheater, the regenerative heat exchanger is used for preheating the combustion air in power plant furnaces and industrial furnaces, and, when used as a gas preheater, the regenerative heat exchanger is used for preheating in waste gas purification, for example, in catalytically operating reactors, or for reheating in a gas washing plant. The heat exchange between the hot gas which flows off and the air supplied in a counter-current flow to the gas is achieved either by a rotating heating surface carrier or, when the heating surface carrier is stationary, by hoods which are arranged on both sides of the storage masses and continuously rotate about a common axis.
The heating surfaces or storage masses of such regenerative heat exchangers are composed of two differently profiled steel sheets which have a thickness, for example, of 0.5-1.3 mm and may be coated or enamelled. Corresponding to the cell-like construction of the circular heating surface carrier, the steel sheets are bundled and are placed with fit in the individual cells of the heating surface carrier. The heating sheets are bundled by means of massive boxes or frame supports which are placed around the bundled heating sheets. When the heating sheets are arranged tangentially, which is usually the case because of the more stable placement of the bundle, it is conventional to hold the heating sheet bundle together by means of head plates at their head ends which are parallel as related to the trapezoidal shape, wherein the head plates are connected to each other at the upper and lower sides through horizontally extending rods each. The heating sheet bundles are arranged in accordance with the gas flow direction, i.e., they are usually arranged vertically.
In this manner of constructing the heating sheet bundles which has been known for a long time, the massive support means not only increase the weight of the bundle, but they additionally use up a significant portion of the available assembly space; this is equally true for sheet layers of the heating sheet bundle arranged tangentially or radially. Consequently, it is unavoidable that the free flow cross section for the passage of air or gas is reduced.
SUMMARY OF THE INVENTION
Therefore, it is the primary object of the present invention to simplify a heating sheet bundle of the above described type. In particular, it should be possible to mount the bundle in a manner which has less weight and an improved flow through the bundle is to be achieved.
In accordance with the present invention, on at least two oppositely located sides of the bundle, at least the two outer profiled sheets are constructed as a pair of sheets connected in a dimensionally stable, sandwich-like manner.
When mounting a heating sheet bundle with tangentially aligned profiled sheets, the two outer profiled sheets are the two end sides which extend parallel to each other, and when mounting a heating sheet bundle with radially aligned profiled sheets relative to the heating surface carrier, the longitudinal sides of the bundle extending in a diverging manner in accordance with the trapezoidal shape of the heating surface carrier cells are constructed with a pair of profiled sheets in accordance with the present invention. Consequently, the heating sheet bundles no longer require heavy end plates or even a complete surrounding housing; rather, the pair of outer profiled sheets which essentially form a hollow box carrier ensure a sufficient stability; the stability is further improved by the fact that vertical outer rods of the profiled sheets are connected to horizontal rods at the upper and lower side of the bundle, so that a strap-like bracing of the heating surface bundle is achieved.
The sandwich-like connection in the manner of a hollow box carrier of at least the two outer profiled sheets of the heating sheet bundle produces, in addition to reducing the weight, especially a better utilization of the available assembly volume in the heating surface carrier and, thus, an increase of the active heating surface area. This is because, contrary to the conventional end plate arrangements or circumferential frames, the profiled sheets of the pairs of profiled sheets are capable without restriction of being utilized, in the same manner as all other heating sheets of the bundle, as heating surfaces with the corresponding free cross sections over the entire area of the individual cells; consequently, the heating sheet bundle provides a higher thermal capacity. Simultaneously, the blockages in the passage cross sections of the individual cells are reduced, so that lower flow losses of the heat-exchanging media and a lower pressure drop can be achieved. Since the flow cross sections are not reduced in the case of the sandwich-type connection of the hollow box carrier, it is possible to construct the heating sheet bundle with pairs of profiled sheets on all sides if desired, i.e., in a circumferentially closed manner, and, thus, to provide an even greater stability.
In accordance with a further development of the present invention, one of the profiled sheets of the pair of profiled sheets is undulated and the other sheet is corrugated. Consequently, the pair of profiled sheets is always composed of one profiled sheet which is wave-shaped to a greater extent and one profiled sheet which is wave-shaped to a lesser extent; when several pairs of profiled sheets are provided at the sides of the bundle, the two types of profiled sheets are arranged on top of one another in a regular alternating manner.
In accordance with a preferred embodiment of the invention, the profiled sheets are connected to each other at welding spots. The two sheets of a pair of profiled sheets or the sheets of several pairs of profiled sheets can be connected to each other in accordance with the spot-welding method in an automatic manufacturing process to produce the dimensionally stable composite body in the form of a hollow box carrier so as to produce the support means surrounding the bundles; welding is carried out at those points where the sheets contact each other. This is because, for reasons of thermal technology and flow technology, the profilings of the undulated sheet extend obliquely relative to the profilings of the corrugated sheet. Spot-welding can be carried out as soon as the two profiled sheets are placed on top of each other; the profiled sheets may be manufactured, for example, in accordance with the method known from DE 41 22 949 A. Alternatively, instead of using spot-welding, the two or more profiled sheets can be connected to each other by means of screws or rivets.
In accordance with a preferred embodiment of the invention, the end faces of the horizontal rods are located on the same level as the end faces of the radial walls of the cells of the heating surface carrier. The great dimensional stability achieved by the sandwich-type construction forming the hollow box carrier makes it possible to arrange the horizontal rods of the heating sheet bundle on the same level as the cell walls at the upper and lower end faces of the heating surface carrier. Corresponding to the number (usually two) of the parallel horizontal rods, this results in an additional radial sealing contour and, consequently, in a lower media leakage. This is because not only each individual cell wall of the heating surface carrier provides a seal against the respective radial sealing plates, but also serving as seals are the support flat irons
Koster Gerd
Moll Winfried
Schluter Siegfried
Apparatebau Rothemuhle Brandt & Kritzler GmbH
Atkinson Christopher
Kueffner Friedrich
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