Industrial electric heating furnaces – Resistance furnace device – With heating element detail
Patent
1983-11-28
1986-08-05
Envall, Jr., Roy N.
Industrial electric heating furnaces
Resistance furnace device
With heating element detail
373134, H05B 306
Patent
active
046047549
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a suspension device for loop-shaped resistor elements in furnaces, particularly in furnaces insulated with ceramic fiber materials. Such fiber materials provide important advantages, such as effective insulation, low heat capacity and lower total costs than e.g., bricks. However, the ceramic fiber materials also have certain disadvantages, such as high porosity, low strength and a tendency to crumble.
Various arrangements have previously been suggested on how to mount electrical resistor elements in furnaces insulated with ceramic fiber materials. Thus, U.S. Pat. No. 4,272,638 discloses a device for the suspension of meander-shaped element loops on horizontal ceramic rod elements being fixed to the furnace wall, which consists of fiber material blocks, by means of fasteners holding the rod element against the furnace wall. Along its length, the rod element is provided with grooves or recesses in which the upper end portions of the meander loops are secured. However, the assembly and dismounting of the rod elements are rather complicated.
OBJECT OF THE INVENTION
The object of the invention is to achieve an improved suspension device permitting a high heating power per unit area of the furnace wall and enabling a simple installation and dismounting of the resistor elements, e.g., in connection with repairs of the furnace lining. Another object is to permit the extensive use of standard parts.
SUMMARY OF THE INVENTION
These objects are achieved, according to the invention, in that the supporting means for the substantially horizontal rod element consist of consoles adapted to support the rod element at a distance from the furnace walls and that the resistor element loops form dense winding coils hanging freely from the rod element substantially in a flattened helical configuration. Hereby, one may easily and advantageously use helically wound or bent resistor elements, particularly of a metallic material, and preferably of Fe-Cr-Al alloys (e.g., of the type sold under the registered trade mark KANTHAL), which are resistant in most atmospheres even at temperatures as high as about 1300.degree. C. Owing to the fact that the resistor element loops are supported at the top by the rod element and hang freely therefrom at a distance from the furnace wall, the entire resistor element can easily be dismounted by mere lifting of the rod element with the resistor element supported thereby, e.g., in case the furnace walls need to be repaired or partly replaced. It is hereby a great advantage that the element loops are hanging freely at a distance from the furnace wall, since the resistance material may become rather brittle after a long period of operation and, thus, cannot withstand much mechanical strain or load.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the invention will appear from the detailed description below of several preferred embodiments, reference being made to the appended drawings.
FIG. 1 shows schematically in elevational view a suspension device according to a first embodiment, with consoles arranged adjacent to the terminal portion of the resistor element;
FIG. 2 shows the device according to FIG. 1 from one end thereof;
FIG. 3 shows in a perspective view one of the consoles of the device according to FIG. 1;
FIGS. 4 and 5 show schematically in elevational views the joint between the terminal portion and the resistor element for flat elements bent edgeways and round resistor elements, respectively;
FIG. 6 shows a cross section of a console according to a second embodiment;
FIG. 7 shows the console according to FIG. 6 in a perspective view;
FIGS. 8 and 9 show two modifications of the console according to FIGS. 6 and 7;
FIGS. 10 and 11 show in perspective views two additional embodiments of the rod element; and
FIG. 12 shows in cross section a third embodiment of a console.
DETAILED DESCRIPTION
In FIG. 1 a furnace wall 1 is schematically shown, said wall being assumed to consist essentially of an insulating, ceramic f
REFERENCES:
patent: 1630368 (1927-05-01), Woodson
patent: 1645293 (1927-10-01), Reid
patent: 4154975 (1979-05-01), Sauder
Bulten-Kanthal AB
Envall Jr. Roy N.
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