US1456892A - Best available cop - Google Patents

Description

May 29, 1923.

1,456,892 G. M. LITTLE PROTECTED ELECTRODE] FOB-ELECTRIC FURNACES Filed May 24, 1921 WITNESSES:

INVENTOR 20 GeoryeML [ff/e ATTORNEY Patented May 29, 1923.

UNITED STATES PATENT OFFICE.

GEORGE M. LTTTLE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

IEROTECI'JPED ELECTRODE FOR ELECTRIC FURNACES.

Application filed May 24, 1921. Serial No. 472,093.

To all whom it may concern:

Be it known that I. GEORGE M. LrrrLE, a citizen of theUnited States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Protected Electrodes for Electric Furnaces, of which the following is a specification.

My invention relates to electric furnaces, and particularly to electric-resistance furnaces, and it has for. its object to provide means to protect the electrode of an electricresistance furnace against oxidation by entering air.

In my copending application, Serial No. 454,776, filed March 23, 1921, I have disclosed an electric furnace having a carbonaceous resistor. the individual elements of which are held in their operative positions relatively to each other and in the furnace by means of an elongated electrode which is resiliently pressed against the re sistor. i

A certain amount'of oxidation of the electrode takes place in the furnace wall through which the electrode extends, and my invention has particular reference toa method for protecting the electrode at this place.

In practicing mv invention, I provide a well or hopper in the furnace wall through which an electrode extends, and placetherein a mass of granular carbonaceous material surrounding the electrode. The well is open to the outside, permitting of tamping the granular material tightly around the electrode and of renewing the same whenever this becomes necessary by reason of its oxidation.

In the single sheet of drawings,

Figure 1 is a view, in vertical section, of an electric-resistance furnace comprising the device embodying my invention, and

Fig. 2 is a view, in section, of a portion of an electric furnace comprising a modification of the device embodying my invention.

An electric furnace comprises an outer metallic casing 11 provided with suitable supporting members 12. An outer layer of heat-insulating material 13 comprises a plurality of bricks or blocks of. any suitable refractory material. An inner layer 14 comprises a plurality of bricks or blocks of any suitable high-temperature resisting re- 1 fractory material used in electric furnace work. i i

The walls 14 are suitably spaced apart to provide a furnace chamber 15 of any suitable or desired contour and dimensions.

A heating member 16 is located in the chamber 15 and comprises a plurality of carbonaceous elements of the type disclosed in my hereinbefore mentioned application. The elements ofthe member 16 are pressed together by means of an extended carbonaceous electrode 17 which operatively engages a graphite end block or plate 18, a similar rear end plate 19 being provided in accordance with the usual practice.

A water-cooled contact terminal 20 has \vedging engagement with the 'conically tapered end of .the electrode 17 and is maintained in engagement therewith by means of resilient compressing means comprising a helical spring 21, a threadedstud 22, a nut 23 and a washer=24. The expanded end of the stud 22 presses against the contact terminal 20, an insulating member 25 being interposed therebetween. The resilient compressing means illustrated schematically only, it being understood that any suitable compressing means may be employed. An asbestos ring 26 may be located in the outer walls and the metallic casing to preventcurrent leakage from the .contact terminal 20.

During the operation of the furnace, the inner and outer walls may separate a slight amount by reason of their being built separately and having relatively different coefiicients of expansion, and the individual bricks may also separate sufficiently to permit air to enter.

As the furnace is provided with an opening 27 to permit of the introduction and the withdrawal of metal articles, a certain amount of air will enter through this opening. and means are disclosed in the hereinbefore mentioned application for producing a sooty vapor in the chamber to protect the resistor and the electrode. The electrode is. of course, hottest at the end immediately adjaccnt the graphite block 18 and coolest at the outer end where the water-cooled contact terminal 20 is located. If no provision is made for protecting the electrode in the walls 13 and 14, air entering between the individual layers of bricks and flowing up wardly between the walls 13 and 14 would strike the electrodeand oxidize the same by reason'of its relatirely high temperature.

Means, comprising a well 28 located in the two walls 13 and 14 and extending to below the electrode 17 and to the upper end of the furnace and filled with granular carbonaceous material 29, serves to pmbeetthe clot-- trode 17 against such enterin air.

I may use powdered lamp-hlaek, charcoal, granular coke or graphite, and it is to be noted that the well opening to the outside of the furnace provides means for introducing such granular carbonaceous material around the electrode intermediate its length, which granularmaterial maybe tightly tampc'd around the-electrode and is-readily renewable, whenever required, by reason of the oxidation -of the mass of material immediately adjacent the electrode. Such oxida tion is, of course; a chemical union oi: the

' oxygen in the cnterino air with the carbonaceous material, and, i permitted to affect the electrode; would cause a reduction of its cross section.- I

As the position of the electrode, where it passes through the walls 13 and 14, is not the sameat all times during the operation of the furnace, by reason of unequalexpansion and contraction of the various purts'of-the furnace,-=provision is made in the resilient compressingmeans for permitting the electrode the electrode 17 through the walls 13 and 14 is easily ef'l'ccted without in any way decreasing the ellic-iency of the protection provided.

In the modification illustrated in Fig. l,

the well 28 does not extend to the top of the furnace, but is open at the side of the fun nace immediately above the electrode and its associated contact terminal. A suitable container 30 may be provided to retain the granular material in place in the well. The operator is thus permitted to renew or tamp the granular material from the side, instead of from the top of the furnace It may be noted that the device embodying my invention rovides a relatively simple means surroun ing the electrode for chemically uniting with an entering oxidizing fluid to protect the electrode while permittin free movement of said electrode relative to the walls and to the mass of protecting material.

Various modifications may he made in the device embodying my invention, without de parting from the spirit and scope thereof, and I desire that only such limitations shall he placed thereon as are imposed by the prior art or are s ivcilicnll i set forth in the appended claim.

I claim as my invention:

An electric furnace comprising :1 plurality of furnace walls, an electrode. extending horizontally through one of said walls and movable relatively thereto during operntion of the. furnace, a well in said wall, a quickly renewable granular oxidiznhle barrier in said well surrounding said electrode over a por tion of its length intermediate its ends, said barrier being adapted to prevent chemical action of entering air upon said electrode but permitting free movement of said electrode relatively to said wall.

In testimony whereof, I have hereunto Subscribed my name this 18th day of May, 921.

GEORGE .ll. LITTLE.

Images