Industrial electric heating furnaces – Arc furnace device – Furnace body detail
Patent
1983-01-24
1985-01-01
Envall, Jr., Roy N.
Industrial electric heating furnaces
Arc furnace device
Furnace body detail
F27D 112
Patent
active
044919522
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an electric furnace dome that is hermetic and made of ceramic material and that is cooled at its center and supported with the aid of external tube systems to improve durability.
The simplest and most inexpensive dome construction is one that is made of bricks or cast from mass, the dome being in reality dome-shaped, in other words the surface is outwards in the shape of a round ball. If the dome is built of ceramic mass, its structure is generally quite weak, which is the reason why it must be supported at those points where there are for example openings. Not even supporting however always helps, but the resulting construction is still weak at least under situations of malfunction. Fully supported brick domes that have a planar surface area also used. Such structures are generally very expensive and difficult to repair and service. Externally cooled domes have become known as a third alternative, as for example the box beam construction that has become known from the Finnish patent application No. 783705. A drawback of this dome also is its expensiveness, as well as the energy losses caused by great amounts of cooling water and the danger of explosion in the case of leakage, electrode breakage or other such inconvenience to production.
The purpose of this invention is to avoid the drawbacks of domes in accordance with technical level and achieve an electric furnace dome whose construction expenses as well as costs of using are moderate and which is hermetic and endures use.
The characteristical features of the invention are given in the accompanying patent claims.
The invention is described in more detail in the following by referring to the accompanying drawings of which
FIG. 1 illustrates the side view along the cutline in
FIG. 2 of an electric furnace dome in accordance with the invention,
FIG. 2 illustrates an electric furnace dome in accordance with the invention viewed from above.
An electric furnace dome in accordance with the invention is made of ceramic material (mass and/or brick) and is constructed so that the dome's stationary edge 1 is separated from the easily repairable or changeable center 2 by water-cooled tube systems 3 that are supported from outside of the dome. Further the dome's center 2 which is under great strain is watercooled by spiral tube systems that are inside of the dome structure. In the figures the spiral tube systems in the center of the dome that are around the openings 4 for the electrodes are indicated by the number 5, the spiral tube systems around the material feed openings 6, some of which are in the center of the dome and thus watercooled and some on the edge of the dome, are indicated by the number 7, and the spiral tube systems that are directly in the center of the dome are indicated by the numbers 8 and 9. The spiral tube systems are at the same time a part of the dome's watercooled support system, because the spiral tube systems are supported at both of their ends by supporting rods 10 from outside of the dome, as FIG. 1 illustrates for example for the spiral tube system 9.
The input pipes 11 that are fastened to the openings 6 for raw material feed are equipped with ceramic lining and are tightened to the corresponding part 2 and 1 on the dome with a thin insulating layer 12 that consists of ceramic wool and/or fibre and that due to watercooling endures the electric furnace's temperatures well. The effect of the watercooling reaches however beyond the insulating layer which to a certain extent increases the dome's tenacity to endure practical circumstances in the possible cases of malfunction caused by for example the overheating of the furnace.
Further the raw material's input pipes 11 go through the dome and that section 13 that is on the inside of the furnace is a fixed part of the dome's cooling system and thus increases the dome's hermetic sealing because the input pipes are watercooled at that part of the dome and on the inside of the furnace by a spiral tube system 7 that is supported from outside of the dome.
The openings 4
REFERENCES:
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patent: 2718537 (1955-09-01), Basler
patent: 2752410 (1956-06-01), Olsson
patent: 2871278 (1959-01-01), Sandvold
patent: 3129274 (1964-04-01), Lindblom et al.
patent: 3375317 (1968-03-01), Hansen et al.
patent: 3429973 (1969-02-01), Carter et al.
patent: 4197422 (1980-04-01), Fuchs et al.
patent: 4273949 (1981-06-01), Fischer et al.
Honkaniemi Matti
Iisakka Veikko
Jankkila Martti
Krogerus Helge
Lajunen Erkki
Envall Jr. Roy N.
Outokumpu Oy
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