US1076518A - Electric furnace. - Google Patents

Description

1. RENNERF BLEG 0 FURN APPLIGATIO I ED FEB. 26, 1912.

1,076,518. Patented 001;. 21, 1913.

UNITED STATES IVAB RENNERFELT, 0F HALMSTAD, SWEDEN.

ELECTRIC FURNACE.

Specification of Letters Patent.

Patented Oct. 21, 1913.

Application filed February 26, 1912. Serial No. 680,003.

To all whom, it may concern:

Be it known that I, lvAR R NNERFELT, a subject of'the King of Sweden, and a resident of Halmstad, in the county of Halland and Kingdom of Sweden, have invented certain new and useful Improvements in Electric Furnaces, of whichthe following is a specification.

My invention relates to improvements in electric furnaces in which the heat is generated by means of arcs and the objects of my invention are: to provide means for changing of the vertical location of the source of heat in the interior of the furnace at the will of the operator; to afford facilities for operating the furnace with arcs independent of the charge or, if so desired, with arcs between the charge and the electrodes; to afford an easy access to the interior by arranging the electrodes and their supports so as to permit their Withdrawal entirely from the openings 'in the walls made for the electrodes; to afi'ord means for an automatic stirring of the molten charge; to arrange the electrodes in such a manner as to permit the operation of a furnace on any system of electric power supply, direct current or alternating current of any phase number or frequency; to facilitate smelting of cold scrap using power from small units of distribution, sensitive to disturbing influences regarding the voltage regulation; to build the smelting crucible of an electric furnace so as to obtain a considerable mechanical strength at the same time utilizing as much of the energy supplied as possible. I gain these objects by arranging the electric furnace as illustrated in the accompanying drawing in which Figure 1 is a vertical section of a furnace with electrodes arranged in a horizontal o.- sition as well as vertical or rather r ial position. Fig. 2 is a sectional view of the furnace in Fig. 1 on the line w-.'1:. Fig.3 is a vertical, part sectional, part side view of a furnace having horizontal electrodes which may be tilted in different angles,

whereas those of Figs. land 2 are intended to be adjusted vertically by moving the el e trodes transversely to t elr axls ma ntamlng the same always parallel to its original location. a

The radial electrode may be omitted in case'of using direct or single phase current but it may also be connected to the neutral wire in a 3-wire system or it may be used with single phase current taking the sum of the currents in the end electrodes. On polyphase systems, which are transformed to twophase current, if the power suppl is .threephase current, said radial electr e. is

to be connected to the middle point of the secondar of the twophase transformer and.

carries ,t e geometrically resulting current of the components in the two phases. 7

Throughout the several views similar parts are'indicated by similar letters of reference. 1

The smelting hearth of the furnace has the shape of a cylindrical crucible 1, resting on rollers 2 so as to be easily rotated for discharge of slag and metal through thespout 3. The'charge of for instance molten steel and slag is indicated by t. A projection 5 from the lower part of the crucible serves as means for stirring or mixing the charge by rotating the crucible one way or the other.

The heat is enerated by means of arcs between the ralli'al electrode 6 and more or less horizontal electrodes 7. The radial electrode is longitudinally adjustable but not otherwise. The, horizontal electrodes are supported by suitable means 8 permitting the raising or lowering of the electrodes according to where the arcs are wanted in the crucible.

a trolley 10 or. someother arrangement as for instance hydraulic or pneumatic lifts located on the round.

The radial e ectrode need not be electrically insulated but isprovided with cooling me ium by means of a waterjacket 11. The

horizontal electrodes are cooled by similar Waterjackets' 11 and well insulated electri- The means for said ad'ustment may be either a hoisting rope 9 rom.

cally' from each other and from the radial electrode.

Means for adjusting the length of the arcs are shown In 3 and consist of a pipe 12 insulated from the cooling jacket by means of aacking 13 of asbestos or similar material. nside of the pipe is an elastic packing of copper gauze 14. making a slidin contact w1th the electrode with enough frictional resistance to cause the electrode to follow the movement of the pipe in or out. 'Said movement is caused by any approved means, suchas a screw, a hydraulic plunger ing pendent on the drawing.

the pipe and the pac of this is sinking down when being sme cylindrical linin or other suitable arrangements not indicated The current is conducted by means of clamps 15, on pipe surrounding same;

ing between it and the electrode-is of copper or other conducting material. The horizontal electrodes of Fig. 3 are supported ontrunnions or journals 16 permitting an angular movement of the electrode around an axis located at right angle to the longitudinal axis of the electrode. The electrode is protected from the furnace heat by highly refractory material supported by the trunnions 16 and moving with the electrode.

By giving the end electrodes of'Fig. 1 a suitable inclination toward the charge and then lowering them close enough to the surface of the charge together wlth the radial electrode,

to the electrode the electrode or the if. such be used, it becomes possible to heat the bath'directly by arcs operaton the charge itself making same part of the path of the current. The same mode of operation is attained in Fig. 3 by tilting the electrodes sufliciently. It is clear that this highly facilitates the operation of the furnace on cold scrap: Such a charge offers a much varying resistance to the current, if the arcs are playing on the scrap, causing bad short circuits very frequently with difliculties in maintaining a smooth service. It is better, then, to use arcs indeof the charge, as long as it has not become molten and to send the current through the charge, only after a bath of fluid'm'etal and slag has been obtained. It is possible to charge more scrap into a furnace, where the electrodes may be located a proper distance above the top of the charge and to maintain a minimum of distance between the arcs and the charge, as the tpp ed. In this way the highest efliciency will always be maintained. The cylindrical shape of the crucible not only gives to the walls and roof a high degree of mechanical stren .h but also serves to save energy as part of the heat which is radiated upward is reflected down to the surface of the charge. Another part of the heat absorbed by the walls may be recovered by tilting the crucibleso as to bring the charge into contact with the heated walls thereby absorbing some of the heat. The maintenance of a furnace of this character is relatively cheap as a new may be rammed into the crucible at smal cost with a minimum of time, labor and material.

Having now fully described my invention side of the crucible means of a shield 17 of Stockholm and-- I claim and ,desire to secure by Letters Pat ent of the United States of America:

1. In an electric furnace the combination of a crucible arranged to be rotated around a horizontal axis, electrodes projected into the crucible from opposite sides, another electrode projected vertically through the into close proximity to the inner ends of the first said electrodes and means for adjusting the relative distance between the three inner ends of all the electrodes, the electrodes bein so arranged that an arc is established from the vertical electrode to each of the other electrodes.

2. In an electric furnace the combination of a crucible arranged to be rotated around a horizontal axis, a shield at each end of the crucible, an electrode extending through each shield, another electrode extending in radial direction through the wall of the crucible, and means for adjusting the shields in vertical direction.

3. In an electric furnace the combination of a crucible arranged to be rotated around a horizontal axis, an electrode through each end of the crucible, another electrode extending vertically through the side of the crucible into close proximity to the inner ends of the first said electrodes and means for adjusting the relative 'distance between the three inner ends of all the electrodes, the electrodes being so arranged that an arc is established from the vertical electrode to each of the other electrodes.

4:- In an electric ofa crucible arranged to be rotated around a horizontal axis, an electrode through each end of the crucible, another electrode extending vertically through the side of the crucible into close proximity to the inner ends of the first said electrodes, means for adjustin the relative distance between the three lnner ends ofall the electrodes, the electrodes being so arranged that an arc is established from the vertical electrode to each of the other electrodes andmeans for rotating the crucible so as to vary the distance between the ends ofthe electrodes and the surface of the molten charge within the crucible.

Signed at Stockholm in the county of the Kingdom of Sweden this 30th day of January A. D. 1912.

IVAR RENNERFELT.

furnace the combination

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