US1672667A - Electric furnace - Google Patents

Description

Jane 5, 1928.

H. L WATSON ELECTRIC FURNACE Filed Nov. 13, 1926 2 Sheets-Sheet Inventor: Haw-"oldTTWatson,

fittmrney June 5, 1928.

H. L. WATSON ELECTRIC FURNACE 2 sheets-sneak Filed Nov. 13, 1926 Invntow: Hare Id Twatsmm HisAtta n g;

Patented June 5, 1928.

narrow a. Wesson. or am,

T0 GENERAL IEJIZIECIJRIO,

ETJECTRIC FURNACE.

Application filed November My invention relates to electric furnaces, more particularly to high tem rature electric furnaces and has for its 0 ject the provision of a simple, reliable and ellicient high temperature electric furnace.

More specifically my invention relates to an electric furnace of the resistor type which is capable. of maintainin a temperature suficiently high for the usion and treatment of the more reiractory metals and com pounds. The furnace may be successively used with temperatures as high as 1900 to 2%0" (1, and it is especially useful in the fusing of large masses of quartz.

For a more complete understanding of my invention reference should be had to the accompanying drawings in which Fig. l is a vertical sectional view of an electric fur uace embed 'ng my invention, Fig. 2 is a plan view 0 the device shown in Fig. 1, Fig. 3 is a. view showing detailsof construction, while Fig. 4 shows a modified form of electrical connections.

Referring to the drawings, my invention in one form comprises a heating chamber which is defined by walls made of heat refractory material, a charging opening 11 be- .ing provided in the bottom wall. The side and bottom walls of the heating chamber arepreferabl lined with recrystallized carborundum bricks 12, although any sufficiently heat refractory material which will be inert in the carbonaceous-silicious atmosphere prevailing fusing quartz may be used. Such other materials which'might be used under certain conditions are alumina, zirconia and thoria. The top of the furnace chamber may be formed of similar bricks or, as shown in the drawing, it may be formed of graphite slabs 13 over which is placed a layer of silicasand- 14. The recrystallized carborundum bricks forming the side and bottom walls are heat insulated by means of a layer of zirconium silicate bricks 15 outside of which are two layers 16 of fire brick.

1 This furnace structure rests on ametallic supporting plate 17 having a central aperture 18 registering with the bottom opening 11. The plate 17 rests on brick piers llland 20 on which the furnace structure is supported at asufiicient height for convenience in charging. A steel framework 21 is provided around the entire structure to facilitate the operation of a platform 22 on which the charge is placed. This platform comprises 13, 193E. Seriallto. 148,188.

ametallic support 23 which rests on parallel cross bars piers 19 and 20 and having their ends connectcd by vertical rods 26 to the ends of an elevated frame 27 above the furnace. This frame is free to move in a vertical direction between guides 28 and 29 and as shownmay be raised and lowered to 'raise and lower the platform 23 by means of a chain hoist orcrane 30., A bottom wall 31 made of successive layers of heatrefractory and heat insu.

lating bricks similar to. the structure of the? chamber and on this ledge so as to surround the charge is a self supporting heating resister. comprising alternate horizontal bars 33 and upright rods at. These rods and bars are made preferably of graphite and they are electrically connected together to form a continuous heating resistor extending around the wall of the heating chamber, this resistor comprising horizontal lengths 33 formed of the flat bars and vertical rods 34. The bars 33 at the lower side of the resistor rest on the ledge 32 and form supports for the resistor.

Any suitable electrical connection may be providedbetween the bars 33 and the rods 34 of the resistor. A very convenient electrical as well as mechanical connection be as and extending between the.

1,672,662. UNITED stares PATENT on:

tween them is provided by slightly tapering the ends of the rodsllal and forming holes in the ends of the bars into which the tapered ends of the rods are forced. Thisform of connection is shown in Fig. 3. The tapered end of the rod 34 is inserted in the hole 35 in the bar 33 by hand and twisted slightly and at the same time forced cndwise into the hole. This has been found to give a very good connection which is ver inexpensive and may be easily and quit: :ly made. The connection also facilitates the d sasscmbly of the rods and bars for repairs. It a furnace. The assembly of the resistor will be carried out in the heating chamber itself to a greater or less extent, as found most convenient, free access being bad to the heatit ingchamber through the large charging openin 11 in the bottom. The eating resistor is connected at each end to terminal electrodes 36 end 37 made of a suitable heat refractory material, such as gmlphite. These two terminal electrodes are ui t into the furnace wall at points ad acent each other; Preferably the connection lay-Letters Patent of the United States, is: the electrodes is similerto that providedbe- I between the ends of the heating resistor and tween the rods and bars forming the re sistor itseli. As shown the electrodes enter, theheating chamber attire bottom so that their up er surfaces are substentia'llg on s ottom bars 88; Each 'end of-the rcsistortermi- 'netes insn upri ht bu'rB end. these two end bar's 'ore'forced ivy hand into apertures pro-- vided for them in tiieends oitiie'elcctrodes.

eret' with their outer ends.

The electrodes will'be connected to the ter- "minels of :1 suitable electrical supply source;

by means of connections, not-shown, coop- Eac electrodeis provided viitii e looped or hairpin-charged ipe 38 which isfcemented in the'electro e,t' e ends of the pipes ex tending from the outer ends ofthe elcctrodes. These piyes' extend. to pointsfncar the inside Well 0 the recr s'rsilized 'carbo-i V rundum bricks iinin :t'he urnace cli smber'.

@ooiing Wateris circulated throng-l the pipes Whereb the bus bar connections with the outer ones of the electrodes are cooled and, furthermore; the" inner lining'of r crystallized*carioorundum bricks is cooled around thefinner ends of the electrodes whereby short circuitsare prevented. It

williie understood that the extremely high temperature prevailing in the-furnace;

the'recrystellized ccrborundum matcrial of the lining has a compnrutiv'elylow electrical "this cooling ncense were not "provide to the support 23 when the platform is 'eie With this Water cooled arrangement operat n voltages of 125' volts or more may be use, A suitable seal is provided for-the bottom of the furnace .conslsting or". e flange 39 sc cured tothe plate 17 around the opening 18 WlHCh fitS m a channel member 40 secured voted to closed position. A suitable sealing material suciias fire cleywill be provided in" the channel member for embedding the flan c 39, v

arious electrical connections may be proneed ior the resistor. For example; as

- skilled in the art Without departin the spirit of my invention the scope or which --hating chamber a ledge extendin jointed -che'rnloer supported on "said ledge so that opening it will While I have described my invention as embodied in concrete form and as operating in s specific manner in accordance with the provisions of the potentstatutes, it should be understood that I do not limit my invention thereto since various modifications thereof will suggestthemselves to those from it set forth in the annexed claims, I

vWhetll claim as new and desireto secure 1. A high temperature electric furnace 'comprising'zliest refractory Wells forming at heeting chem beunnd a heating resistor in sfsici chamber comprising a plurality-oi. here of heatretrectory materiel arranged vertiv ceiiy in spaced relation around the-sidewall of said chamberand cross pieces joining ssid bars at their upper end lower ends to ijoinmgtlie upper and lower v ends of vss-ici ours to form e continuous hosting resistor,

the lower cross pieces constituting the supporting means for said resistor.

3 high temperature electric furnsce comnrlsing heat refrectoryiwalis'forunng a heat ng chamber and e heating unit in said chamber comprising'upright bars ofiieet refracto'ry mster'ial'v und horizontal cross ieces of heat refractory niateriel joining sei bs'rs in'toe continuous resistor, said c ss nieces being provided with apertures, an sci burs be ng prov ded with ta cred ends fitting into sand apertures in e ectric'si engagement I .therewith. resistance and 'as a, result the electrodes '4; Iliigh temperature electric furnace comprising heat refractory wells forming a eround said chamber-and integral with ssi Wells, a, heating resistor extendin around said cliomber resting on said is go, said resistor comprising alternate upright and lio'rizontei bars made of heat refrectory'msteriel. j

5. A high temperature electric furnace comprising heat refractof-ji walls forming a,

heating chamber having schsrgin ope-Inn Pin the bottom, sledge surrounding sci opening and a heating resistor composed of iiars of. refractory'msterial in said when the chure is introduced through the e surrounded the resistor.

a e'rs oe'r 6. A high temperature eiectric furnace comprising heat refractory walls forming a heating chamber, 5, pair of electrodes made of heat refractory material extending 5 through the wall of said chamber at points adjacent each other, a heating resistor extending around said heating chamber havin its ends connected to said electrodes, an cooling means associated with said electrodes 10 whereby thetemperature of the inner lining of the furnace is maintained sufficiently low to prevent short circuits between said electrodes.

7. A high temperature electric furnace comprising heat refractory walls forminga.

heating chamber a pair of electrodes made of heat lfafififitOl'f, materiel. extending through the well of amner at points adjacent each other, e a; I'ESlSiiOl' tending around said chamoer he; connected to said electrodes, said ing formed of alternate upright and horizontal bars of heat refractory material con-. nected together to form a. continuous heating resistor, the lower horizontal bars forming supports for said resistor and electrical connections between said electrodes and said resistor.

In witness whereof, I have hereunto set my hand this 29th day of October, 1926.

HARGLD L. WATSON;

Images