Electric furnace

Application filed August 28, 1923. Serial No. 659,738.

To dll whom it may concern:

Be it known that I, Thaddeus F, Baily, a citizen of the United States, residing at Alliance, in the county of Stark and State of Ohio, have invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification.

This invention relates to improvements in electric furnaces of the type in which a current of electricity is passed through resistance material to produce the necessary heat, and more particularly to a resistance trough located above and surrounding the hearth up which the material to be heated is placed.

It is customary to support this trough upon radial supporting walls which interfere with free access to all parts of the hearth, limiting the working surface of the hearth considerably and causing hot spots around the under side of the trough.

The objects of the present invention are to provide in a furnace of this type, a trough containing the resistance material which is supported entirely from the side walls of the heating chamber, thus leaving the entire hearth unobstructed and easily accessible.

Another object of the improvement is to provide a resistance trough of this character which is mounted in a removable section of the furnace and which comprises a removable and replaceable unit, which may be easily removed from the furnace and replaced when the trough is burnt out.

The above and other objects may be attained by providing a pair of spaced, concentric, annular walls of refractory material, the outer wall being connected directly to the walls of the heating chamber and the inner wall being supported upon an arched, annular bottom member mounted upon the annular outer wall, a suitable granular carbonaceous material being located in the trough, electrodes extending into the same, and an insulated section of fire brick wall surrounding the trough and with a section of metal shell upon which the electrode terminals are supported.

An embodiment of the invention thus set forth in general terms is illustrated in the accompanying drawings, in which—

Figure 1 is a vertical, sectional view on the line 1·—1, Fig. 2; and

Fig. 2, a horizontal section on the line 2—2, Fig. 1.

Similar numerals refer to similar parts throughout the drawing.

The brick work l^z of the furnace may be supported upon a metal plate 2, and is preferably formed of fire brick having the co lining 3 of suitable heat resisting material forming the hearth 4, which may be concaved as shown in Fig. 1.

A door opening 5 is provided in one side of the furnace above the hearth, and a pour- (>5 ing spout 6 communicating therewith, the door opening being normally closed by the door 7.

The brickwork is surrounded by a nietal shell 8, preferably spaced therefrom, and 70 provided at its upper edge with a sand trough 9.

A removable circular section is supported upon the structure above) described, and carries the heating element. This section 75 comprises the circular brick wall 10, surrounded by the insulating material 11, such as kieselguhr or the like, a circular steel shell 12 covering the outside of the section, and provided with the depending angular so flange 13 arranged to be seated in the sand trough 9, forming a sand seal between the sections of the furnace.

An annular rib 14, of carborundum or similar refractory material is built in the 85 Avail 10 and provided with the beveled edge 15. The annular outer wall 16, of the trough is formed of carborundum or the like and rests upon the rib 14, preferably engaging the inner face of the wall 10. oo

The annular bottom wall 17 of the trough is also formed of carborundum or similar refractory material, and is arched as shown in Fig. 1, the outer beveled edge 18 thereof resting upon the beveled edge 15 of the rib, 9a the inner edge being beveled as at 19 to receive the beveled lower edge 20 of the annular inner wall 21 of the trough, which is also formed of carborundum or the like. The trough is thus supported entirely upon ioo the wall 10 which forms a part of the heating chamber of the furnace.

This annular trough is filled with a resistance body, consisting of a carbonaceous material in granular form, such as crushed 105 coke, graphite, carbon or the like, said resistance body being designated by the numeral 22.

Embedded in the resistance material, preferably at diametrically opposite sides of the 1 io

1,506,281 trough, are the electrodes 23, said electrodes extending through the Avail of the removable section of the furnace, as shown in the drawing. It will be understood that these .5 electrodes are located in an electric circuit, said construction being well known in this art, electric conductors 24 being connected to the terminals of the electrodes and leading to a suitable source of electricity. When the current is supplied to the electrodes, it will be connected from one electrode to the other through the resistance material, thus raising the resistance material to an intense heat.

i > The terminal of each electrode is supported upon a bracket 25 connected to the shell of the removable section of the furnace, thus permitting this section to be removed as a unit, after the electric conductors have 20 been disconnected .from the electrodes, the entire resistance element being thus contained in the removable section.

A metallic sand trough 26 is provided at the upper edge of the shell of the removable 25 section and the roof, comprising the brickwork 27 is covered Avith a metal shell 28 having the depending flange 29 which enters the sand trough 26, forming a sand seal between the removable section and the roof. 3·' Thus, when the resistance trough is burned out, the roof section may be removed and the removable section, carrying the resistance element, may be lifted from the hearth section and replaced by a new re23 sistance section, the roof section being returned to its place, and the furnace is ready for operation.

It will thus be seen that the annular trough containing the resistance material is 40 located above the hearth and surrounds the same, and is supported entirely upon the side Avail of the heating chamber, thus leaving the entire hearth unobstructed, providing a larger working surface upon the 45 hearth, and leaving all parts of the same easily accessible, and eliminating the hot spots around the trough caused by the usual supporting piers.