US1147703A - Electric furnace. - Google Patents

Description

J. W. BROWN.

ELECTRIC FURNACE.

APPLICATION FILED APR.22. 1914.

Patented July 27, 1915.

I N VEN TOR.

V. N w Wm UMM H w av W N H D J WITNESSES.-

snares PATENT JOHN V7. BROWN, 0F LAKEWODD, OHIQ, ASSIGNOR T0 NATIONAL CARBON COMPANY, 0F CLEVELAND, OHIQ, A CORPORATION OF NEW JERSEY.

ELECTRIC FURNACE.

Specification of Letters Patent.

Original application filed January 8, 1912, Serial No. 670,071. Divided and this application filed April 22,

T 0 all whom it may concern:

Be it known that 1, JOHN W. BROWN, a citizen of the United States, residing at Lakewood, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Electric Furnaces, of which the following is a full, clear,

and exact description.

This application is a division of my ap plication, Serial No. 670,071 filed January 8th. 1912. v

The improvement relates to electric furnaces and more specifically to that type in which the charge is a conductor of electricity and iscontinually fed through the furnace.

llt is particularly adapted to the manufacture of graphite, and to the baking and calcining of cokes and .other carbonaceous materials. In the electric furnaces as usually constructed, there is a large waste of heat due in part to the imperfect heat insulating medium of which the body of the furnace is constructed and to the large amount of heat contained in the treated charge when it leaves the heatirnc zone.

ln order to continuously move the charge through the furnace it has heretofore been foundnecessary to cool it to the temperature that would admit of its being conveyed out into the open air without injury to the treated product. The cooling has been done by forcing water through pipes in the lower part of the furnace, or by passing them through the treated charge itself. The heat absorbed by the water is all wasted and one of the objects of my invention is to utilize this heat.

Another object is to do away with the necessity for continual supply of cold water which is an expensiveand wasteful method.

Another object of my invention is to preheat the charge so that it will not be neces sary to use so much electric energy.

Another object is to treat continuously relatively small quantities of the charge to a high temperature for a relatively short period of time.

Further objects will appear in the description of my invention, particular reference being had to the drawings in which:

Figure 1 is a central cross sectional view of a continuous furnace in which the charge is preheated by passing a heat absorbing Serial No. 333,640.

gas through the treated material. Fig. 2 is a detail of a pair of carbon bricks used in the furnace of Fig. 1.

Referring to Fig. 1, 10 represents the outer inclosing walls of the heating zone of the furnace, and is made of some heat in sulating material which is a non-conductor of electricity. llhe lower walls are lined with a carbon-section 11 in the shape of a. hollow upright frustum of a cone. A hollow cylindrical section 12 built up of corrugated or grooved carbon blocks such as shown in Fig. 2 rests on the top of the member 11 and has its opening in coincidence with the upper opening of the core. Upon the hollow cylindrical section 12 is placed an inverted frustum 13 similar to the section 11. but preferably made of an insulating material the same as that of the furnace walls. In this manner an upper and a lower chamber 13' and 11 respectively are provided with a narrow intermediate chamber 12'.

.a lower electrode 14 having a terminal 1(3 is placed beneath and in contact with the lower conducting section 11. Upper electrode H and its terminal 15 are similarly placed on top of the member 13.

With the construction thus disclosed, the current will flow from the upper electrode 1 through the upper part of the charge until the built up section 12 is reached. Here the greater part of the current will pass down through the constricted portion of the charge which is surrounded by the section and a small part of it will flow through the section 12. \Vhen the section 11 is reached the current will again divide, most of it flowing through the carbon section 11 directly to the ,lower electrode 14-. A small part of the current, however, will flow through the lower part of the charge to the lower electrode. The corrugated surface of the sections 12 increases the resistance to such an extent that only a small part of the current passes therethrough. This high resistance is easily obtained by placing the grooves of one block transverse to those of the adjacent block, thereby securing a number of point contacts of high resistance. However. the carbon blocks will be heated somewhat by the current passing therethrough and will aid in heating material in the constricted portion of the charge. it will thus be seen that the. charge tit) another screw conveyer 18.

in the chamber 12' surrounded by the built up section 12 can be quickly heated to a very high temperature. The charge, consisting usually of granular coke, is fed into the top of the furnace by the screw conveyer l7 and removed from the bottom of The rate of charging and discharging the material being treated depends primarily upon the temperature to which the charge in the constricted opening is to be heated, although this may also be controlled to a certain extent by adjusting the current.

The fan 19 forces an inert gas into the bottom of the furnace and withdraws it from the. top. The gas 1n passing through the heated charge in the chamber 11 cools it so that it may be removed into the air by means of the conveyer 18. The hot gas which has been previously heated by passing through the treated charge and through the constricted-portion delivers up its heat to the untreated charge in the chamber 13 and in this manner preheats it. The furnace shown rial, means to provide a constricted opening in the drawing is greatly reduced in height as compared with its width, but this is for the purpose of illustration. In practice the furnace would be 20 or 30 feet high and the space above and below the heating zone would be great enough for the gases to absorb the heat from the charge in the lower part of the furnace and deliver substantially all of it to the charge in the upper part of the furnace so that it will emerge therefrom in a substantially cool state. A valve 20 is also provided for regulating the supply of gas which is to be forced through the charge.

Having described my invention, what I claim is: I

1. In an electric furnace for treating granular material, inclosing walls, positiveand negative electrodes spaced apart in the direction of movement of the material, chambers for the treated and untreated material having a constricted opening therebetween adapted to be filled with material being treated.

2. In an electric furnace for treating granular material, an upper electrode, a chamber above said upper electrode, a lower electrode spaced from said upper electrode in the direction of movement of the material,

a chamber below the lower electrode and means to provide a constricted area between said chambers whereby an electric current passes between the electrodes and through the material in the constricted area.

3. In an electric furnace for treating granular material, an upper electrode, a chambe' above said upper electrode, a lower means to provide a constricted area between said chambers whereby an electric current passes through the electrodes, and through the material in the constricted area, and means for admitting and removing the material at the predetermined rate.

4. In an electric furnace for treating granular material, positive and negative electrodes spaced apart in the direction of movement of the material, means to provide a constricted area between said electrodes whereby an electric current passes through the material in the constricted area to strongly heat it, and means for removing the heat from the treated charge and delivering it to the untreated charge.

5. In an electric furnace for treating carbonaceous material, a chamber for untreated material, and a second chamber for the treated material. electrodes situated in each of the chambers adapted to heat the matebetween said chan'ibers. means for admitting and removing the treated material at a predetermined rate, and means for cooling the treated material whereby the untreated material is preheated.

6. In an electric furnace for treating granular material, inc/losing walls, positive and negative electrodes, chambers for the treated and untreated material having a constricted intervening space therebetween adapted to be filled with thematerial being treated and to be heated by the passage of current therethrough, and means for forcing a fluid within the walls of said chambers containing the treated material whereby heat is absorbed from said treated material, and delivered to the untreated material.

7. An apparatus for preparing granular carbon, consisting of an upper and a lower chamber a relatively narrow throat connecting said chambers; means to cause an electric current to pass through the material in said throat when in operation, an exit for the prepared carbon at the lower part of the lower chamber, whereby the exit of the prepared carbon therefrom may be controlled to control the movement of carbon particles through the throat in the path of the elec trical current.

In testimony whereof, I hereunto aifix my signature in the presence of witnesses.

JOHN IV. BROIVN.

IVitnesses:

Ina J. ADAMS, H. G. Gnovnn.

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