US1628376A - Electric furnace - Google Patents

Description

y 1. R. VALENTINE ELECTRIC FURNACE Filed Feb. 26. 1925 Inventor: I r'vlng R.Vanlerwtime by W Patented May 10; 1927.

UNITED STATES PATENT IRVING R. VALENTINE, OF ERIE, PENNSYLVANIA, .ASSEGNUR- Ti) GENRE COMPANY, A CGREORATIQEQ" OF IQ'E'W' 5563K.

ELECTRIC FURNACE.

hep'lieatieu allies February 22%, 19%. Serial N0.

My invention relates to electric furnaces. more pari'ieniarly to elertrie' furnaces for melting metals by passing an electric current through the charge ilself. {lIHl has for its oh- ;ieer the provision of a method and means Wherehy higher current deneities can he med and the rapidity of heaiing: thereh ineieasm'l.

In el cirie furnaces of this hype. for nielh ind nieials there is a lendenry fer the nioiieu ehzarge o be disrupted lav the se- .-alied pinch force which is inridenhd to the passage oi" an electric current. through any eondue iorv This pineh force is due to the magnetic: lieid surrounding the conductor. and has 'ihe eii' ee'l ol squeezing or constricting the eenduelior. Vihere rhe conductor is a liquid this force will he strong enough to rupture the circuit if the current density is high enough. When rup-- ilure of the circuit oeeure the action of the furnace is inieru'iitteut and otherwise unsai'isfaetoryf ConsequentlvQ the maximum perinissihle cur ent densii v For satisfactory operation is liu'iil'ed to some *a'lue lewer than hat which will produce ruplure of ihe cireuii. It 'loliows that the power input and hence the rapidity of heating are liiniied by the pinch effect.

In'carrying out nrv invention I provide an auxiliary reservoir oi moii'en charge which in connected with the eurreni: mi'i'ying portion oi the charge and serves in simpiy niollen charge lo prevent: rupture by the piiu'h :foree Wherehy higher eurreni densities may he used.

For-iv more complete umhrrslanding of .urv invention reference should he had. in the ac mu'ipanlving drawing in which Fig. l is vertical FQPiiUD view oi an eieetrie furnace en'ihodyingg' my invention. while Fig. 2 is a. .Qerl'ion view aioug the line fZ-2 of 1 looking in the direction of lhe arrow".

iie'i erring to the drawing, in carrying out my inveniiou in one form i provide a refraci'ouv erueihle 10 which is moulded or othe wise shaped lo provide a ventral reservoir ll for the charge 12. Communicating with the reservoir subetanlieliy ai hottein. there; of on the left hand side are two subewnlud'ifi Suhslanl'iallv vertieal holee or epenin and [h are provided in he reirarafion 3 10 having iheir lower ends eoinmu iCl. i

Willi the channels I"; and poiuls suhsfani'iall niidwa of the i .i' the ehennelsv ihe upper ends oi hire l? and 18 are open and eoneeinienijqx ihe molten eh; rgge l2 rises in (he heies and SHHIQS the 9111116 hydroshv'rie head an charge in the reservoir 11. a

The opposite or right hand side 0'- reservoir 12 ie similarly ai'i'e ged, l h1g1 two horizontal ducts reading: from reeervoir 11 to a eavit v or space 1.). and ave mihslantially veriieul holes: or openings iv emineei'ingr with the chzunlela at peiniisiaui'ialiy midwa of lhe iengihs oi the neis. Only one of (he duels mu." 1 rig-ht hand side of the reservoir zue shewn in. the drawing. these heingz indieaied h re en ce rharaerers 20 and 21 re elerrrode 22 is inserled in ii I the molten charge.

The erueihle '10 may he formed in. ways for exeznpie, by taniping material from which the erue' around a suiiahly eheped co crucible may he iiiouided solid ailr whieh i he'eenrral reservoir l'i and arious cavities and openings eonneri'ed it \viil he cut out of this moulded hieeh. Preferably a metallic protecting and reinforcing easing 223 is provided around erueihle The eieelrodes i6 and form eerveni means for eonducting an eleeirie eurreni re and l'rnu's (he ehare'e. Obviously suiiahie means for iillS purpose 1110. in place of the elecj'rrodee. The eleearedee s the electric circuit hetvveeu the elecroles. a her which additional charge in solid "gorin may be placed in the reservoir 11 and Due to the much smaller cross seca oi the ducts 13 and 14 and the rent lensitics m the charge contained in these is much higher than in the other parts oi the cruciole and cruisequcntly heat will be generated in the ducts at a correspondingly greater ate: in "fact a compa ativel small amount at heat \Tlll be generated in the reservoir l2 and in the cavities l? and. 19. It will he observed that the portions ot the'cl'iarge in the substantially vertical holes leading into the horizontal ducts do not carr any current and therefore no heat is generated in the charge contained in these holes.

li'hile the charge is being heated by the current passing through it. caused to circulate by the pinch force exerted. on the charge in the horizontal ducts. and the hot metal in these ducts is in this manner mixed with the colder metal in the other parts of the furnace. in order to increase the rate oi" heat generation in the horizontal ducts whereby the rapidity of heating of the charge is increased. it is desirz-ihle to use con1- paraiivcl r high current densities in the ducts. The molten charge in the vertical holes acts as an auxiliar supply of molten charge under pre ure due to its hydrostatic head. and since this charge is not; traversed lrv the heating current. is not subjected to the pinch "force. and therefore. tree to low into the cl anncls and till any voids nhich may be formed momentarily due to thc ctlcct ol' the pinch force tending to s ueeze oil or rupture the charge in the ducts. It is thus possihle to successfully operate the furnace with much higher current densities in the ducts than Would be possible it the intermediate holes were not provided. This current density may he manv times the dcnsit possible without the holes.

in addition to the advantage of much ll'rczitcrrapidity oi heating oi the charge. a orrespondingly more vigorous circulation oi the charge is obtained by reason of the increased pinch force. ll hilc the pinch orce s prevented from opening" the electric, circuit it is active in producing circulation so that overheating oi the metal in the ducts prevented. and the charge maintained at a substantially uniform temperaembooied in concrete form and as operating 7 in a specific manner in accordance with the provisions of the patent statutes, it should be understood that. I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of nrv invention. the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States. is:- 1. An electric Furnace comprising a refractory crucible for the charge provided with a 'duct in which the charge is heated hv an electric current passed through it" and a reservoir providing a hvdrostatic head of molten charge communicating with said duct intermediate the ends thereof from which molten charge supplied to said duct to revent rupture of the electric circuit by the pinch force acting on the molten charge in said duct.

2. An electric furnace comprising a retractorv crucible providing a reservoir for the charge and a duct communicating with said reservoir in which the molten charge is maintained under pressure by the hydrostatic head of molten charge in said reservoir. and menus for passing an electric current through the charge in said duct to heat the charge. said crucible heing provided with an upwardlv extending Opening connecting with said duct intermediate its ends into which a portion of the molten charge is forced from said duct hv hvdrostat-ic pres. sure and returned to said duct to prevent rupture of the electric circuit therethrough bv the pinch force acting on the molten charge in said duct.

i gtric -lnrnace comprising a re- TIHCKTOTT crucible forming a reservoir for the charge and a duct connected to said rcscrvoir substantially at the bottom thereof into which the molten charge is forced by the hvdrostatic head of charge in said reservoir. means tor producing an electric currentin the charge in said duct to heat the charge. and an anniliarv reservoir for the molten charge connected with said duct.- between its ends into which molten charge is supplied from said duct to he returned to said duct to prevent rupture of the electric circuit thcrcthrough by the pinch force aeting on the molten charge in said duct.

4-. An electric furna e comprising a relractorv (llN'll'llt providing a reservoir for the charge. a plurality of cavities. ducts connecting said cavities and said reservoir substantially at the bottoms thereof. and suhstantiallv vertical openings connecting with said ducts at intermediate points there- Ill;

" electrodes immersed in the 11103191; rfi'm'rge in said cavities, a source of electrical supp1y connected to said electrodes whereby a cu! rent is passed through the molten charge in said ducts to heat the charge said openings providing hydrostatic heads 0"! malten uharge from which charge is supplied. un-- der prcssur r: 4'0 saiii ducts is ture 0f the wet-firm CHCkZl'CS QWI'EUEECU the pmch famea actmg 0n the nwi ysn c1 wherwfi my hanfi this 19th TALENTENEU

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