US950879A - Electric furnace. - Google Patents

Description

"L THOU.

LEGTR PRHAGE.

APPLICATION FILED SEPT. 1, 1909.

Patellis@ Ela?. l, 19M).

5 SHEETS-SHEET 1.

J. THOMSON.

ELECTRIC FURNAGB.

APPLICATIONv FILED SEPT. 1, 1909,

Patented Mar. 1, 1910.

2 T E E H s S T E E H S 5 Mventor by M m,

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fjA-ttesrtj l (L THOMSON:

Hmmm@ Emmen n APPLIATION FILED SEPT. 1, 1969. @sg/@E Patented Mar. l, 1910.

5 SHEETS-SHEET 3 I I @WL mma J. THOMSON.

ELECTRIC FURNAGE.

APPLIGATION FILED SEPT. 1, 1909.

Patented Mar. 1, 19.10.

5 SHEETS-SHEET 4.

@ML (MM Affili.,

JOHN THOMSON,

OF NEW YORK, N. Y., ASSIGNOR TO IMBERT PROCESS COMPANY, OF

NEW YORK, N. Y., A CORPORATION OF NEW YORK.

vELECTRIO FURNACE.

Specification of Letters Patent.

Applieationled September 1, 1909.

Patented Mar. i, 1910.

serial No. 515,698.

S'J all whom it may concern.'

Be it known that I, JOHN THOMSON, a cicizen. of the United States, and a resident of the borough of Manhattan, of the city of New York, in the county and State of New York, have invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification, refer ence being-had to the accompanying drawings, forming a part hereof.

This invention relates particularly to im. provements inv resisters of electric furnaces and to their arrangement and disposal in the furnace chamber with a View to-most effectually realizing the widest range of adaptability and the highest thermal efficiency.

One of the principal objects of the inven tion is to provide a resister, which, while being composed of a plurality of elements, is self supporting; that is one which does not require any extraneous means of support. between the terminals, whereby the resister may be entirely free from or out of contact with all parts of the refractory and, in fact, uspended in space within the furnace cham- Another object of the invention is to provide a resister which may have its resistivity increased or decreased in different zones whereby to correspondingly change the current densit within itself; which shall be capable of lieing formed by the established methods of manufacture; which shall be readily applicable to various types of furnace and to which the furnace and its heating chamber are conformable in a manner to derive both the maximum of temperature ad the. highest rate of delivery, or volume, f heat-units in a given time from a given amount of energy.

in` accordance with the present. improvements, the foregoing is realized by forming,

the resister, preferably of carbon, from a l plurality of parts constructed and arranged to interlock one with the other, or one or more with others, and also to interlock with or be sustained by the terminals, in such manner that the resister is in free space and may be built either above, or below, or atE the sides of a heating chamber; and furthermore, the cordinative construction of the? furnace chamber is such that t-he delivery of i the heat waves from all portions of the eX- posed surfaces of the resister is realized in i useful effect upon the charge with the minimum of dynamic loss.

l`n the drawings: Figure l is a plan View of 'a furnace embodying the invention, with the cover removed. Fig. 2 is a longitudinal central section, the planeof the section being indicated by the line 2 2 in Fig. l. Figs. 3 and 4 are transverse central sections,

left and right, respectively, the plane of the sections being indicated bythe line 3 4 in Figs. 1 and 2. Fig. 5 is a transverse central section and Fig. 6 is a longitudinal central section of a furnace showing modifications. Fig. 'l' is a plan view and Fig. S is a vertical central section of a furnace showing other modifications. Fig. 9 is an enlarged detail view of the resister sections and the terminals, to-better illustrate the application thereof, as shown in the preceding figures. Fig. 10 is an enlarged detail view of a resister applied in a modified manner, and Fig. 11 is a diagrammatic detail indicating some of the various forms of construction of elements which may be employed to build the resister.

Referring first to Figs. 1 4 inclusive and to Figs. 9 and 10, one embodiment of the invention will first be described in connection with ,the particular type of furnace shown in these figures. Here, the main body a of the furnace is provided with a removable cover b containing an opening u for charging or for visually inspecting the interior of the furnace, and the resister is a compound one having two sections D and D". which are connected up in series, confined between the terminals c and e at one end and the connector-piece e2 at. the other end.

Each section of the iesisteiwvill be seen to consists of a. plurality of grooved plates d laidn transversely thereof and the opposing faces of 'ivhich are so disposed as to prevent a staggered ariangement` of the whole;'and

in the figures under present consideration,

each resister` element may be likened to a series of round rods laid together lengthwise but having rounded or neck-likejoints along the intersections, thus presenting the form of la iuted plate.' Manifestly when such plates are laid together, with the rounds of one plate in the hollows of another the contacts will be in lines, and when a series of such plates ne set between terminals, or a terminal and a connector, having correspondina' llutings, as shown, and held against. displacement endwise, the several parts are interlockcd and the resisterras a` whole is seltsustaimng, its weight and endthrust being` taken whol ly by the said terminals. As comparatively little end-pressure is necessary to maintain the lines of contact along all of the convolutions7 it Will now be apparent that. with such a keyed structure a wide range ot' electrical contact; resistance in ay he obtained and that, beinsc` independent of position for its support, it. can he built in various forms and applied to many types of furnaces. Thus, in Figs. l to 4t, the resister shown si pended in clear space above the i; in jfii. and (S the resister is sus` ed below the retort c, while in Figs. T and f3, the resister is suspended within a circular -furnme casing', in tour vertical sections.l` torni] .fr a hollow square within which av crucible as c, may be set. ln this instance il e convolutions ol the resister plates would be .isc o't' the plates instead of lengthwi llnt while the described arrangement ot' having the resister suspended by the ter-- minais is regarded as the pret'erz'ible this is not, au inclispensahle 'lcature and in 't'act there may be circ!nnstances where the said su n4V n might equally well be upon the tui-nace walls direct'. Thus, the retractories c, r7 l to (L shown in Atull lines, which act as the luunary supports tor the teru1inals, and as secondary supports tor the resi er.y siini'ily require to be extended inwai-diy7 as shown by the dotted outlines r2, il :i and t5, when the .ster would be primar'ly supported at each end thereby; and in this wise the terminals may be arranged to be removed without iutert'ering i, h the resister.

.is has already been pointed out in another application i Letters Patent tiled itflay 13, lit/Dt `tlerial No. s955585, in order to main-- lain a practically constant pressure upon the iarbon. which essential to the control ol thc electro-therinacy7 the emi-pressure required to niaintaiii the tinted plates is produced through the intervention of suitably mounted springs c?l` liigs. l, 2 and 6, actuated by :uljustingl screws c", or in the instance of Figs. 7 and 8 by yield- 'ing` steel bands c acting' resiliently against the brick-work. ln this wise7 the exact amount of pressure can readily be applied and also such an extent ot resiliency that the expansion or contraction ofthe resister can tal-fe place withoutsensibly changing its density. lihen a compound resister is used. connected in series, two screw-actuated springs are preferred7 as shown in Fig. l, whose outer thrust is taken by the bar el" which contains the adjusting screws. In thisl instance each sping is located to impart' its thrust through a sliding refractory cinniinging against the connector e2 along interlock ot the] l l l l l l i l l v and bot'` the central axis ot each section otl the rw sister. Now, by placingslidablc carbon rods cw capable ot' being,` impinged when desired againsty the connector and a rolt-n'ietcr, or nie-- ters, as c, connected by a shunt circuit hetween these rods and the inain circuit, it can be ascertained at. once and at any time it' the rate ot" generation ot' energy in both sect ionsI oitl the resister is the same, and il not the rcsistance ot' the said sections can be made thiI same b v proper manipulation ol' thc spring' tension` lllithout. some convenient means olj this kind the rate ot generation ol energy in one section might be much greater than in the other and the endurance ol" the whole would be that ot the overloaded member.

Another advantag'cmls Vleature ot this inrei-locking` resister system is that any side ot a resister may readily he given greater conlnession than the opposite side` thereby corres-poni ingly increasing' the current dein sity and the temperature. e'aiin when a resister is disposed along a hoi izontal vplane` with inist sutlicicnt eiuhpressure to ma he contacts between the tlut'ingfs, its upper portion. duc to its weight, will be under compression whilc its lower portion will be in tension. tending like an arch to separate. .\n cxactly neutral condition, or an exi-,css` can readily be el'lectcd by the simple cxpedien shown in Fig. i), wherein thc 'tacos olt the terminals are slightly beveled so that when the terminals approach cach other horizontally, the pressure will be greater. or more intense. along' the lower line un than the upper n ln practice the actual amount ol' the ditlierenee in spaciin;` between the top om ot' cach plate is ordinaril \v \'cr slight.y say 'from .O02 to .O05 inch: and may be raged with the utmost exactness b v the angle given to the terminals.

lt will be observed in Fin". lninals and the connector are wider than the main portion ol the resister and that rrsisterplatcs d are provided to connect therewith whose widths are approximatcly equal to that ot' the said terminals and connector: the object` and :nlvautaiye ol' this beine' to obtain the largest possible arca ot contact and thereby deliver the current. into the resister with the least possible drop in voltage trom the line connection.

that thc ter A construction ot the resistenis .--ho\\'u in Fig'. l() in which the inlerloclied plates are stacked at a considerable angle to the horizontal, Q2 degrees, as denoted in the drawing. This involves the use ot a. kevlCS llt)

unlike an arch, the lineal length of the resister elements, above and below, are equa-l, the lineal difference being entirely compensated in the key, which would ordinarily be of puregraphite; and consequently the vari- 'ation in its resistance through top or bottom would be inappreciable.

Because of its strength, rigidity and ease of manufacture, the iluted resister plate, with staggered interlock, is regarded as the preferable form; but, will now be shown, various modifications thereof can be made, whereby to meet any or all practical requirements. Thus, in Figs. 5 and 6, the resister is composed of plates Z3 having V- grooves and between the said grooves sepa. ratetubes, as Z4 are interposed. Here each tube acts as akey and yields four lines of pressure contact between each pair of plates. This combination possesses the obvious ad- 'antage of having an exceedinglylarge area of radiating surface. In the various modiications illustrated in Fig. 1l, the tubes d* are shown as interlocking shallow squareshaped grooved plates d5 and d in a manner whereby six lines of pressure Contact are shown for each tube; round rods Z7 are' here shown, substituting the tubes; balls, (ZS may take the place of either and .corrugated plates d1, d, d may be employed, of uniform thickness, where the combination of dl" and d will obtain linecontacts. Finally, should the requirement arise of obtaining' an interlocked resister of the lowest. possible resistivity, this may he realized by combining the two similarly V-groored plates dg, or the corrugated plates d and d as inthese instances the area and intimacy of Contact would be greater than that of flat plates of correspondmg face dimenlt may be pointed out with respect to the arrangement of parts shown in Fig; 6 that this type of furnace readily lends itself to given 0E by the charge would actdetrh. Thus, by

mentally on the carbon resister. simply closing theI side spazes at the top,

carbid 4or the like, shown in dotted' lines y,

`the resister would then be etectively contained in a chamber distinct and separate from that of the charge.

W'hen a compound resister is employed,

in seri and 'arranged after the manner i shown in Figs. l, 2, and 4, it is preferable to use a connector made of Acheson graphite; but the leading-out terminalsl are preferably of amorphous carbon. Thel advantage'is in the higher electrical and thermal conductibility of the graphite, inside of the furnace, and the lower thermal conductiblhty of the carbons to the exterior of the furnace. At normal. temperature the elecay thin plates of recrys allized silicon f toward the bath, retort or Crucible` trical resistance of pure graphite is about.

four times less than amorphous carbon, for like sections; but at high temperatures th'c difference is considerably less. Still, the difference, even at the best, is not negligible when thousands of amperes are to be delivered to the resister. This objection is largely overcome by making the inner portions of the terminals, where they are in contact with the resister, as from i' to s, of graphite, and the outerv portions, as from s to p, of carbon. This can be. accomplished by graphitizing only that portion of the terminals which are to lic inside of the furnace, or by suitably jointing two blocks, one of graphite and the other of carbon.

It will be perceived that if the register plates are under an equal degree of contact between their various lines of inipingement-a condition which the construction already described' can readily obtain and indefinitely continue-that all parts of its sur face will similarly radiate heat; and also that the longitudinal spaces alongl the linecontacts of the tlutings afford an exceedingly effective egress for the heat from every porl tion of the incandescent mass. To realize the utmost efficiency of this condition is the complementary feature of the design, and consists in forming the inner walls of the heating chamber so as to present a surface of incidence which shall be less or more than a right angle to the emitted heat of the resister, thus rendering the incipient energy less effective. to in'ipart heat to the furnace ll and more effective to increase the temperature of the charge. rlherefore, in Figs. 2, 3. 4, 5, 6 and 8, where the arrows :1f indicate heat waves radiating directly from the resister and the arrows .z indirect or refracted waves, theimpingement of-the heat upon the bath, retort or crucible is lgenerally shown as in direct lines, the most effective possible for the contemplated purpose; while the surrounding and overtopping walls are appropriately curved to deflect the direct heat waves received fromv thc various surfaces of the resister and cause them to continue their movement, although with lessened intensity, ,downwardly or upwardly And the consequence of this construction, which is entirely feasible to realize 'in practice, is a material increase in thermal etli'ciency and endurance of the refractories.

From the foregoing, it. will be understood how the invention may be embodied in various types of furnaces. In the several coustructions illustrated herein, the saine reference letters have been used to refer to corresponding parts, so that a detailed descrip-- tion in the case of each of the furnaces specitically alluded to has been unnecessary. Moreover, it. may be noted here that. in all of the illust-rations of the present case, the

Clt

resister has been shown in compound `lorln with its sections connected up in series. ln such instances. the connector-piece between any two sections is7 111echanically considered at least. the equivalentl of a terminal and should be so understood in reading the claims.

It only remains to be stated that the interlocking plate resister may be used. retaining i' many ot the ad fantages that have been pointed out in the foregoing, by being sup ported along its sides` either continuously or at one or more locations, or at one or both sides. For instance7 such an arrangement would be the preferable when Very light line-contacts are desirable.

l claim as my invention:

l. resister for an electric furnace coinprisiug a plurality of interlocking resista nee 1' elements.

resister 'lor an electric furnace con1- pr1s1ng a lnral1tp\' ot interlocking resistVl plates.

2l. resister for an electric furnace coinprising a plurality ot tinted plates.

1li. resister for an electric lurnace. coniprifng a plurality ot' .interlocking carbon plates.

53. A resister for an electric furnace romprising a plurality ot' grooi'ed plates arranged to interlock with each other.

' t3. n electric furnace comprising a. plurality o in a direct line between the terminals and supported entirely free of the refractory.

In an electric furnace, in combination having a resister; l.' elements disposed 13. An electric fi'irnacc haring resister 'composed of separable resistance parts interlocked between themselves and the terminals.

lll, An electric furnace having corne pound resister adapted to be conne tet. parallel or in series and composed sep* arable parts interlocked between themselves, the terminals and the connector.

15. An electric furnace having an inter locked resister engaged by the terminals and suspended thereby in a direct line.

lo. In an electric furnace, a resister coinposed of grooved plates held togJt-her by the terminals.

17. in an electric furnace, a resister com posed ot' groored plates, assembled in staggered relation and held together by the ter-- minals,

1S. in an electric furnacet a res posed o'l grooved pli-ttes. and mea s list l' in. the grooves to interlock the s: all being held tog ther by the it 'annals 1Q. ln an electric furnace.) aA plm-9.1i@ fr.- 1nterlock1ng res1stance elements. and te electric furnace. a plurality f 1' interlocking resistance element a 1' the r sister, and terminals whose faces are with the terminals, a, resister having afplu- '1 rality ot`elcn1ents suspended .from and ina direct line between the terminals and sel l sustaining so as not to require any extraneous nieans ot' support other than the ler ininals.

S. iin electric furnace havinga resirter composed ot separable interlocking re. ance, plates arranged transversely thereot.

9. An electric furnace havinga resister composed ot' separable grooved plates arranged transversely thereof, the said resister being supported wholly .trom its ends.

l0. An electric 't'urnacc having a resister comprising a plurality ot' interlocking re.- sistance elements and terminals ateach end thereof acting` to maintain the interlocking of and thereby to support the elements.

ll. An electric furnace haring a resister coinln'ishig a plurality ot' interlockingresistance plates mounted face to tace and means to support the resister by maintaining a, thrust lengthwise of the same.

l2. An electric furnace having a resister comprising a plurality of grooved plates mounted face to face and terminals at each end of the resister adapted to exert a thrust to keep the plates interlocked with each other. Y

wider than the main portion or the said resister.

Q2. ln an electric turna t.. resister and terminals by ai .it l en wh the resister is arranged to be sel," sustaini D in a direct line, the said terminals having the planes of their faces disposed to impart pr s sure at one or the other sides et the neutra;A axis of said resister.

fin electric furnace having a resister composed ot' interlocking parts, terminals therefor and resilientor reactive means to clamp .the terminals.

24. Au electric furnace having a resister composed of interlocking parts mounted in a plurality of sections between electrical connections, the end pressure on each section being separately adjustable.

25. An electric furnace having an interlocking resister mounted in a plurality of sections between terminals, and a movable electrode or electrodes for connecting each of said sections in a shunt circuit whereby to separately measure its resistivity under actual Working conditions.

26. An electric furnace having a resister mounted therein the inner surface or surfaces ot' the furnace being irregularly curved er sloped so tha the amge @if refraction herefromshai be lese er mme nau a right angle to che iiie of izipingement of ihe emitted heet Waves. o' 27. All eiectrc funace leaving .e resister mounted. che i ie hem. she charge or its centenef by eli eet iwimien imm a portion thereof, 'the une' euface 01 sufaees ef the furmee being ezmed with irl-@grainy curves e rediate heat from Hm ohei pori es of ti siste? in dii @tiene feee from that i-e iines apr/ict.

meets eve comin-ed? one ef the efmiuas it ing between beh ermmais.

in eecie fur-na e having a ifesiste` compese ci 'pzisfaii'by of greeved aes ieiiiilmis iieween which fffiie plaies are con iied e f bem-ing against means to erguet ehe reuiese set 60Min,

t; resister 03% eemeuf ispese n wipe-sied enbetween which die te muy ehe distance tirey free of the rernctory, :1nd yieciing means to retain eue of the termiunis.

31. n an electric furnace, in Combination Y with Jl:he temuinais, resister comprising e plurality of elements disposed 'between the terminals aud supported wholly thefeby, and. means te permit one if the seminels to have e limited range of movementy te compensate for il'xe expansion and contraction of the ye- "ei demente due 'to them-ual @hangt-2,

fm eleetiic furnace having terminal Suppoifts extending under lie resise.

in eleerc furnace having refrac- 'zeles i0 support lie iteri'ninas, said refraeories beim; extended underneath the ends'of the resister izo support ihe sii-me.

34. In en electric furnace uv iesisel' having a piusf'aity ef ucrlocked Diembeis and adapted te be Supported wholly from its ends, terminals therefor .and @Xteued terruina supporta This specieeticn signed and witnessed this 31st dey o' August, A. D., 1909.

JGHN TH I'SO. Signed in the presence ef-- M.. JReLLNe, G. MCGRANN.

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