US872352A - Electric furnace. - Google Patents

Description

No. 872,352. PATBNTED DEC. 3, .1907.

J. 0; KING. ELECTRIC FURNACE.

APPLICATION FILED JAN. 6, 1904.

3 SHEETS-SHEHT 1.

FIG. 2.

INVENTOR; WlT NESSES: J93. QM 0&M 51' ff/0171:3 16,

W m. GUQQQQAQCQL No. 872,352. PATENTED DEC. 3, 1907. J. C. KING.

ELECTRIC FURNACE.

APPLICATION FILED JAN. 5, 1904.

3 SHEETS-SHEET 2.

. TNVENTOR: WXTNXESS'ES: y filly/(2' :MW By Ai/mvzeys,

PATENTED DEC. 3, 1907.

J. C. KING. ELECTRIC FURNACE. APPLICATION FILED JAE. 5, 1904.

3 SEEETSBHEKT 3- F16. 6. k m

W I INVENTOR: WITNESSES: 2% QM I By A ftomeys,

' under similar conditions.

UNITED STATES PATENT OFFICE.

JESSE (JRITZ KING, 01" ST. UATIIARINES, ONTARIO, CANADA, ASSIGNOR TO THE WILLSON CARBIDE WORKS COMPANY OF ST. CATHARINES, LIMITED, 01 ST. (JAIHARIIIES,- CANADA,

A CORPORATION OF ONTARIO.

EIECTBIC FURNACE.

Specification of Letters Patent.

Patented Dec. 3, 1907.

Application filed January 6.1904. Seriel.Ro.1B7.B37.

To all whom it may concern:

Be it known that 1, Jesse Cnrrz KING, a citizen of the United States, residing at St. Catharines, in the Province of Ontario, Canada, have invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification.

Myinvention aims to provide certain improvemcnts in apparatus for electric smeltmg or other electric furnace treatment, and especially for the manufacture of calcium carbid or other substances which are formed 7 1n the manufacture of calcium carbid, for example, a mixture of lime or limestone and carbon is fed into the furnace and the mixture is fused and converted into calcium carbid, with the well known reactions. In the processes most commonly em loyed only the central portion of the materia is fused and reduced, so that the pig of carbid which is formed is surrounded by a crust of the unreduced or partially reduced mixture of lime and carbon. This crust is practically a waste product, and furthermore the cost of separating it from the pure carbid is very great. This expense, and the public nuisance caused by the odor which a dump pile of the crust makes, are very serious objections to the present methods of manufacture. Likewise according to the most common practice a large part of the mixture outside of the crust in the furnace is unreduced, and has to be disposed of by being carried back and mixed with fresh material, which is a matter of considerable ex ense and annoyance.

Iy present invention provides a furnace which can be operated to produce a crustless carbid and to avoid the presence of any substantial quantity of unreduced material. All the material to be utilized in forming the carbid is confined to the zone of fusion, so as to be completely reduced. This is preferably done by passing the material through a die the walls of which closely circumscribe the fused material and which die separates the unreduced material above from the reduced material beneath. The die preferably constitutes one of the electrodes, the other electrode being a pencil arranged with reference to the die so as to provide a space between the two through which the material may be passed. Preferably the die flares downwardly and the material is fed downwardly through the die. By reason of this construction the congealing outer portion of the pig of carbid is easily separated from the wall 0 the die as it moves downward.

My invention contemplates the feeding of the material through the zone of fusion by any suitable means, preferably by withdrawing the product as it is reduced so as to allow fresh material to enter the zone of fusion, the rate of withdrawal being controlled either by hand or by automatic regulating means.

Various other improvements are referred to in detail hereinafter.

The accompanying drawings illustrate embodiments of the invention.

Figure 1 is a longitudinal section, and Fig. 2 a horizontal section on the line 22 of Fig. 1, illustrating one style of furnace; a complete electric circuit being shown in connectlon with Fig. 1. Figs. 3', 4 and 5 are respcctively a longitudinal and a transverse vertical section and a horizontal section on the line 55 of Fig. 3 illustrating another style of furnace. Figs. 6 and 7 are vertical sections of other styles of furnaces, the former being a single-arc furnace and the latter a double-arc furnace.

Referring to the embodiments shown in the drawings, and especially in Figs. 1 and 2, A is a carbon encil constituting one of the electrodes, and B are carbon blocks or sections connected with each other and constituting all together the opposite electrode.

The inner ends of the carbons B are contiguous to each other, as shown in Fig. 2, so that they form substantially a die surrounding the pencil A. The pencil A is of such size as to leave an annular space C between the opposite electrodes. This space may be rectangular as shown, or otherwise shaped. It is through this annular space, across which the current continually passes, that the matcrial D is passed, and first li uefied into a pool, somewhat as shown at It, which subsequently solidifies into a pig F of carbid or other material, depending on the ingredients used. With carbid, which solidifies at a very high temperature, no cooling means is the chute.

ordinarily required, but for products which congeal at lower temperatures the die may be cooled by a water jacket, as shown at e in Fi 3, or otherwise.

lhe current is supplied from a generator G, preferably an alternating current generator. Preferably a transformer II of any suitable type is interposed between the furnace and the dynamo, and reduces the high voltage between; the primary leads J and K to a low voltage. between the secondary terminals and leads J and K". Preferably the feed is controlled by lowerin the pig of reduced material at a rate not faster than that at which the furnace can work with the desired efficiency. The several figures of the drawings show suitable arrangements for this purpose. In Fig. 1 the pig is curved, and passes down through a fixed curved chute L. Preferably this chute is larger than thejjpjgfrfl as'fgsliown, andthe casting M which carries the carbons formin the electrode B is so shaped as to permit t e passage of a portion of the material D outside of the die formed by the meetin ends of the carbon so that the material is fe about the pig and preferably on all sides of it between the pig and the walls of the chute L. Any other suitable nonconducting material may be fed about the pig to prevent injury to the walls of the chute by the high heat and to facilitate the passage of the curved pig through In Fig. 2 the shape of the casting M is indicated, openings N permitting the passage of a portion of the material D as explaine I A suitable mechanism for drawim out the pig F comprises a conveyer made of sections or flights 0 connected together to form a continuous curved platform running on rollers P carried by the fixed structure and moved downward by means of a line of teeth Q forming a continuous rack which is in engagement with a (pinion R driven by a worm gear S controlle by a hand wheel T. The inner face of the sections 0 of the conveyer is substantial] in line with the inner face of the wall of the chute L. The guide rollers and operating parts of the conveyer are carried by a second chute U in the upper open end of which successive sections of the conveyer are added from time to time as necessary.

The relative arrangement of the parts' of the complete furnace and the manner of supporting the several parts may be considerably varied. As shown in Fig. 1 the furnace is supported upon standards V directly carrying the chute L. The casting or ring M is supported directl upon the flanged upper end of the chute E and in turn carries a section W of the furnace proper which carries the-holder X for the upper electrode. An upper section Y is added, carrying chutes or spouts Z through which the material is fed,

a stack a for the discharge of the gases generated, and a stoking door I).

In commencing the operation of the furnace a block'of iron or other suitable material of the shape of the pig F is bolted or otherwise fastened to the-conveyer with its upper end near the carbon A as close to it as possible. The arc being established and the materiall) being fed in, a pool f liquid carbid is formed. Then as the reduction roceeds the operator turns the hand wheel to move the conveyor down together with the pig. When the resistance becomes too high the hand wheel T is stopped or turned more slowly. When the resistance becomes too low the hand wheel is turned more rapidly. The product F passes downward and projects out of the end of the chute L where it is broken off in pieces of suitable size, the material D surrounding the pig being carried back to the reservoir and used over again.

The manner of controlling the rapidity of the process by holding u the pig so as to retain the molten materia in a die permits of the most ellicient utilization of the energy sup lied by the current, both as to rapidit oft e process and uniformity and high qua ity of the product; and above all is extremely cheap compared with prior processes by reason of the avoidance of a practically useless crust around the pig of product. 7 By reason of the currents traveling through only the upper molten part of the pig in passing from one electrode to the other I avoid the loss of energy occasioned in previous single-arc furnaces by the necessity of passing the current through the complete length of pig and maintaining the same substantially liquid; thus securing an output quite as great as in a double-arc furnace. At the same time I am enabled to operate with a sin le arc and thus secure a product of uniformly ood quality throughout the cross-section 0% the pig; a thing which is impossible with a double are because of the localization of the highest heat at oints immediately below the two arcs.

' he forming of the die of separate carbons B permits of maintaining the die of a uniform size as the carbons wear or are burned off at their inner ends. The amount of shortening of the carbons is compensated for by forcing the carbons inward as they wear l so that they constantly touch each other or approximately so to form the die. The upper electrode A may also be made adjustable in any suitable manner. 7

It is not essential to the process that the pig as it emerges from the die shall be surrounded by the material D or any other nonconducting material. The withdrawal of the, pig may of course be accomplished by constantly-driven or automatic mechanism instead of the hand mechanism shown, and

such constantl -driven mechanism may be' controlled by and or automatically. The

the essential point he mass specific form of conveyor shown is not essential to success, a {cat variety of conveyers being adapted to t 0 same purpose.

A furnace difi'ering in some respects from that shown in Fig. 1 though embodying the same general principles of operation, 18 shown inFigs. 3, 4 and 5. The diein this caseis formed of carbon plates B, constituting the lower electrode, and lower lates 0 preferably of graphite, fire brick or ot or material (conductive or not) which will not be injured by exposure to the high heat. The die tapers and is supported in a holder preferably in the form of a casting d supported 'in turn upon legs or other suitable supports V. The u r electrode A may be arr ed with its ower end within the die as in ig. 6, but is shown in this case as sl' htly above the die, though not so high as to cm the solid pig or any portion of it above the die so as to prevent its being drawn downward. The zone of fusion, or at least the pool of fused material, fills the cross-section of the die so that as the li uid solidifies it may be drawn downward. 11 order to hasten the solidification of the material before it asses out of the die (which solidification is esirable though not essential) the lower carbon holder d may be provided with a jacket or tubular space e running entirely around it, through which cold water may be passed. Any other suitable means may be utilized for cooling the die or for cooling the pig directly. The pig may be drawn out in a irectly vertical line A suitable means for holding up the pig and lowering it at a desired rate is shown. comprising a table f upon which the pig rests and which ma be lowered manually or mechanically. hen it has been lowered to expose a desired len th of the pig F the latter may be broken of? as for example at the point 9, and the broken off art removed. lnwardly rojecting blades F1 or equivalent devices iiold u the remaining portion of the pig until the ta lef can be shoved up against its bottom.

The mode of operation of the structure shown in these figures is substantial y the same as that of the furnace of Fig. 1.

Fig. 6 illustrates certain additional modifications which may be made without departing from the spirit of the invention. The lower electrode B is a solid. carbon block in the form or a die with its aperture of uniform cross section throughout its length. The upper electrode A may be elevated above the die a slight distance as in Figs. 1 and 3, was shown it may extend down within the die; to avoid placing it high enough above the ie to permit the partial solidification of the fused material before it can enter the u per end of the die. The feature of BXtCDt ing the upper electrode down within a lower electrode however is not claimed as my invention. In thisfigure means are indicated for re upper carbon A, either for adjusting it for wear or for permitting its gradual movement from the lower part of the die to the u r part in the carrying out of the process. 's means ma consist of a contro wheel 7' the hub 0 which is screw-threade and enages a screw-threaded end of a rod I: carrygulating the height of the mg the electrode. For lowering or drawing down the pig F a pair of roughened rollers In? be provided, geared together as shown one of them carried on a shaft m conrolled by any suitable operatintg device or mechanism, such as the ban -controlled worm shaft m. The lower electrode in this case is supported in a shell of metal 1t constituting the principal portion of the wall of the furnace proper, the upper carbon holder 1: being supported from the top of the furnace as indicated. In every case suitable insulation'o is provided between the parts of the furnace carrying the upper and lower electrodes. The wall of the electrode or die B is tapered at its upper end to ide all the material toward the opening 0 the die.

Fig. 7 shows the application of the princile to a double-arc furnace, that is to say, a ace in which there is an are between each of two electrodes and the fused material. The electrodes A and B may be mounted similarly to the upper electrode of Fig. 6 or in any other suitab e way. The die p is composed of bricks of strong heat-resisting mate-' rial, preferably graphite, and may be supported in a shell 12. similar to that of Fig. 6. l he passage through the die may be of uniform cross-section as shown, or may be tapered as in Figs. 1 to 5. By making the die larger, or arranging the electrodes A and B closer together, they may be lowered into the die. Or they may be arranged as shown a slight distance above the top of the die so that the solid product is formed directly in the die. The withdrawal of the solid pig may be effected by ooved rollers."

In commencing t e operation of the furnace shown in Figs. 3 to 7, an iron box or other block of suitable material is arranged with its top so high as to support the molten material in proximity to the u per electrode or electrodes, and is gradually owered as the pig is formed. It is understood that the arc is ormed in the first place'in each of the several furnaces by introducing some of the mixture on top of the false bottom and adding broken coke or other form of carbon on to of this until it touches the upper electrode, a ter which the current is turned on and the material is fed in in suitable quantities. The rollers l of Figs. 6 and 7 may be held against the ig with a yielding pressure, or may be rigitPas shown. Preferably their turning is controlled by a worm wheel (see Fig. 6) so that they are automatically locked in any position to which they are moved. Likewise o I a worm wheel or equivalent locking mechanism should be used to control'the movement of the table 1' of Figs. 3 and 4. The length of the dies will vary with the material to be formed. With a product which solidifies at a very high temperature a solid pig will be formed a short distance below the upper electrode, and for this product a comparatively short die such as is shown in Fig. 1 will be suflicient. For a product which solidifies at a lower temperature or more slowly the die will be longer, and it may even be necessary to apply special cooling means such as described for-insuring that it shall be sufliciently hard to be handled in a pig when it emerges from the die. I It may of course be slightly plastic so that as it emerges it s reads out laterally to a slight extent, and or the most efficient carrying out of the process it should be sulliciently stiff to be he d up and in turn to hold up the fused material above it. It should have a solidified shell capable of retaining the hotter and still liquid mate? rial in the center at the time that it emerges from the die, and the point at which the end of the pig is broken off should be sulliciently far away from the die to permit of the solidification of the material throughout its crosssection.

The differences in detail presented b the several dii'l'erentforms of the invention s iown are in general interchangeable. That is to say, a furnace may be built comprising any desired features selected from each of the several furnaces described.

In previous ingot furnaces the lime and carbon had to be very finely ground so that the molten lime should not percolate too freely into the material outside of the zone of fusion and thus form a pig of irregular quality and pith a thick crust. With my improved apparatus in which all the material passes through the zone of fusion and is reduced therein, the former expense for fine grinding is not necessary. Also in previous ingot furnaces it has been found im racticable to use limestone, the crust forme case'being very hard as compared with that obtained by the use of lime. With my improved apparatus producing a crustless pig, limestone may be substituted for lime with a considerable saving in expense.

Though I have described with great particularity of detail certain embodiments of my invention, yet it is not to be understood that the invention is limited to the particular embodiments described.' Various modifications thereof in detail and in the arrangement and combination of the parts may be made; by those skilled in the art without departure from the invention.

What I claim is 1. In an electric furnace for the produc tion of calcium carbid or the like, means for in such a "e'fdsely circumscribing such zone, and means for progressively passing all the material to be utilized in forming the product within'said walls and through sa d zone of fusion and dischargin it in solidified form, said means engagin the solidified product, whereby is obtaine a pig devoid of crust.

2. In an electric furnace for the producmaintaining a zone of fusion in which the material is fused, adie having walls closely c'ircumscribing such zone, and means for withdrawing the material from said die progressivel as it solidifies and thus holding up the fuse material within said die.

3. In an electric furnace for the producfor fusing the material, and a die thro h which the fused material passes and by which it is shaped, and which separates the unreduced material above from the reduced material beneath, and means for withdrawing the material from said die progressively as it solidifies and thus holding up the fused material within said die.

4. An electric furnace having a die through which the material passes, means for fusing the material within such die, said die adapted to retain the product until it is sufficiently solidified to emerge in a solid pig, and means for controlling the rate of emergence of said 5. An electric furnace havin a die through which the material passes, said die formed of rcfracto I conductin material and serving as one (if the electrodes, a' second electrode suitable current passes between them the material within the die is fused and reduced, and means for controlling the passage of material through the dle adapted to retain the product therein until it is sufiiciently solidified to emerge in a solid pig.

6. An electric furnace having a die composed of sections of carbon formin an electrode, said sections being adapted for radial adjustment.

7. An electric furnace having a die through Y which the material passes, means for fusing the material within the upper portion of such die, said die prolonged sufficiently below the zone of such fusion to permit the fused product to sufficiently solidify within the die to emerge therefrom in a solid pig, and the die flare at its discharge end to facilitate the emergence of such pig.

- 8. An electric furnace having a die through which the material passes, means for fusin the material within the upper portion of sucl die, and means for cooling the lower portion of such die, whereby the molten product is sufficiently solidified within the die to emerge therefrom in a solid. pig.

9. An electric furnace having a die, means for fusing all the material which passes tion of calcium carbid or the like, means for.

tion of calcium carbid or the like, means arranged adjacent thereto whereby when a amass through said die, a chute on the discharge side of the die, and means for feeding between the chute and the solidified roduct emerging from said die a quantity 0 granular material.

10. An electric furnace having a die, means for passing a portion of the material throu h said die and fusing the same, and means or pasgin a portion of the material outside of sex emerging from the die.

e and about the solidified product 11. An electric furnace having a fixed curved chute, and means for conveying the reduced material in a curved pig through said chute.

In witness whereof, I have hereunto si ed my name in the presence of two subscri ing witnesses.

JESSE CRITZ KING.

Witnesses:

DOMINGO A. USINA, FRED Wm.

Images