US1106381A - Electrode for furnaces. - Google Patents

Description

O. HERING.

ELECTRODE FOR FURNACES.

APPLICATION FILED DEO.1Z, 1912.

Patented Aug 11, 1914 2 SHEETSSHEET 1 [NVENTOR WITNESSES ATTORNEY G. HERING.

ELECTRODE FOR FURNACES.

APPLICATION FILED DEC. 12, 1912.

Patented Aug. 11, 1914.

2 SHEETSSHBET 2.

M INVENTOR UNITED STATES PATENT OFFICE.

CARL HERING, OF PHIL ADELPHIA, PENNSYLVANIA.

ELECTRODE FOR FURNACES.

To all whom it may concern:

Be it known that I, CARL HERING, a citizen of the United States, residing in the city of Philadelphia, county of Philadelphia, and State of Pennsylvania, have invented certain new and useful Improvements in Electrodes for Furnaces, of which the fol- -lowin is a s ccification.

My invention resides in an improved electrode of general application, and more particularly adaptable to use with electric furnaces in conducting current to or from a charge, such as molten conducting materlal, Within the furnace. And more particularly my invention .resides in an improved electrode for use with electric furnaces of the. character described in my prior Patent No. 988936 and in my prior application Serial No. 638615; and for use with any fluid resistor, and particularly a fluid resistor confined in a channel.

My invention resides in an electrode which is more particularly adapted to the conduction of alternating currents, especially those which are large in amperage and of mod erately high frequencies. In ordinary elec* trodes for alternating current and of necessarily large section the skin effect causes the material in the interior to become nearly useless as an electrical conductor, hence it acts to freely conduct the heat from the furnace because it is not hindered by any (1 R heat generated by the current. Hence my electrode is made to partake of the form of a shell or cage having ample cross section but being so thin that the current flows through practically its entire section thereby generating C R in the entire section to hinder the flow of heat from the interior of the furnace. And my invention resides in an electrode of the character above described in which the electrode efliciency is made very high upon the principles set forth in my prior Patents Nos. 999719 and 999720.

My invention resides further in an electrode associated with a molten resistor in or by which energetic flow of the molten material is produced, the arrangement and structure being such that the flowing or moving molten material does not impinge upon the material of the electrode, which would cause a washing away of such elec trode, but impinges upon a refractory non- Speciflcation of Letters Patent.

Patented Aug. 11,1914.

Application filed December 12,1912. Serial No. 736,252.

conducting wall which'withstands the flow or movement of the molten material.

My invention resides in the apparatus and structure hereinafter described and claimed.

For an illustration of one of the many forms my invention may take reference is to be had to the accompanying drawing, in which:

Figure 1 is a vertical sectional View through a form of my improved electrode associated with an electric furnace or the like. Fig. 2 .is an end elevational view of the large outer end of the electrode. Fig. 3 is an end view of a modified form of electrodes for use with direct current or a single phase current. Fig. 4 is an end view of a modified form of electrodes for use with three phase current. Fig. 5 is an end view of a modified form of electrodes for use with two phase current. Fig. 6 is a sectional view through a modified form of electrode which is peripherally dis-continuous. Fig. 7 is a top plan view of the electrode structure .of Fig. 6 removed from the furnace. Fig. 8 is a sectional View, parts in elevation, through an electrode of the character illustrated in Fig. 6, the electrode elements extending beyond the furnace Wall.

Referring to Figs. 1 and 2, a portion of a furnace wall or body F of refractory material provides a hearth, crucible or basin H containing the furnace charge of molten metal M or other fluid conducting material.

Communicating with the hearth H is a resistor channel 0 filled with the molten metal M and constituting a molten resistor R which communicates at its lower end with the electrode E.

The resistor R may be of any suitable di- I mensions or shape, but is here illustrated as and assumed to be a resistor of the character described in my prior Patent No. 988936 producing the pinch effect which not only heats but alsoautomatically stirs the molten bath. Indeed it is within my invention to omit the channel C entirely and bring the upper end of the electrode E into communication with the large mass of molten material in the hearth E, the upper end of the electrode in such case forming part of the bottom of the hearth.

The electrode E is of a hollow or shell like formation, a block or plug B of refractory insulating material filling the cavity Within the electrode E. At its outside end the electrode E has a ring or flange D of suitable heavier section for purposes of mechanical strength and for the further purpose of accomodating a pipe or channel P through which may be circulated water or other electrode cooling medium, the medium being introduced for example at p and then circulating around the flange or ring D in the pipe and flowing out at p. Inasmuch as the electrode E and the flange or ring D will generally be of cast metal, though my invention is not limited thereto, it is desirable, to secure proper flow of the cast metal and to prevent cracking on cooling, to provide a circumferentially extending core or cavity to insure small sections of metal on either side thereof. To the outer face of the ring or flange D are secured by screws or bolts 6 the conductors A leading to one terminal of the source of current.

It will be noted that the electrode E where it is of greatestdiameter, as at E is of thinnest section; and that the section of the electrode E increases'as the electrode E becomes of smaller diameter as at E. The rate of increase in thickness of section with decrease of diameter of electrode toward the end thereof is preferably made such that the total cross section of the electrode from its thinnest to its thickest portions remains substantially constant. The construction lends itself-also to securing the advantage of high electrode efliciency referred to in my prior Patent No. 999,719. The length and cross section of the electrodeE is preferably made such that the current flowing through the electrode raises it at its end of smaller diameter by its own resistance to a temperature substantially equal to the temperature of the molten material with which it cooperates; that is, such that the C R heatdeveloped in the electrode by the current transmitted through it shall be substantially equal to twice the heat conduction loss through the electrode which would exist when no current which S represents the secondary of a transfiows through it.

By making theelectrode hollow, as described, all of the conducting material in the electrode is usefully used in conducting alternating current, and the heat conduction loss through the electrode can then be made a minimum. Furthermore the location within the bee-hive or egg-shaped electrode of refractory material B provides means against which the force of the flow of the molten material produced by the pinch eifect in resistor R or by any other means may act, thereby sparing the end of the elec trode from such flow or wash which would cause it to melt too far back, thereby shortening the effective electrode and lengthening the effective resistor. The How referred to impinges upon the member B in the vicinity of the point G, molten material filling the space immediately above and to either side of the point G and extending down to some point where the electrode E changes from solid to molten condition.

In another of its aspects my invention may be considered as comprising a resistor R confined in a channel G between two masses of molten material, one being mass M and the other being the molten material at the upper end of the member B and at the bottom of the resistor R. In such case the electrode does not fill the end of the resistor channel as in the case illustrated in my prior Patent No. 988,936. It is to be understood that for such use of the resistor R this mass of molten material below the resistor R and at the upper end of the member B may be made of any suitable size or magnitude.

It will be understood that in Fig. 1 only one electrode and channel are shown; the other terminal of the source of energyv may communicate through another electrode E with the bath M through a second channel C; or the connection of the other terminal of the source of energy to the bath or molten material may be made by any other suitable means. And it is to be understood that with an electrode such as herein described a plurality of channels may be employed in the relation set forth in my application Serial Number 638,615 Where a force is availed of produced by the re-action of the currents in conductors inclined with respect to each other.

While the electrode E is here shown as having its axis vertical, 'it is to be understood that it may be disposed in any other suitable position and that the resistor R j need not be co-axial with the electrode, and the axis of the resistor R need not be a straight line, but may be curved or other- .wise disposed, and that in any event the axis of the resistor R may beat an angle ;with the electrode E.

In Fig. 3 I have shown an arrangement in former, or it may represent a source of direct current. One terminal of the source S is connected to one electrode E and the other terminal to the other electrode E. In this 'case each electrode is of the form of a half of a bee-hive, the two halves of course being insulated by the furnace walls or refractory insulating material.

In Fig. 4., S, S and S represent the secondaries of a three phase transformer, three electrodes being shown and each having, as

in the case ofFig. 3, an associated resistor It. And in Fig. 5, S and 8 represent the secondaries of a two phase transformer there being in this case four electrodes and four resistors. Y

It is to be understood in connection with the construction illustrated in Figs. 3, 4: and 5 that more than one resistor channel may be associated with each electrode as hereinbefore explained; and that the electrode may directly communicate with the bath and not through intermediate resistor columns, as hereinbel'ore explained in connection with l. And it will he understood in connection with Figs. 25, l and 5 that all the resistors communicate preferably with one and the same bath of molten material. Also that any of the other well known systems of connections of polyphase currents may be used.

As is well understood, the skin effect of an alter rating current increases with the frequency of that current. Accordingly with the increase of frequency of the current passed through electrode F, such as hereinliel'oi-e described, the thickness of the electrode shell will be less for greater frequency for a given cross section of electrode material tor a given current carrying capacity. And while the electrode herein illustrated is assumed to be of circular cross section, or functions oi circular cross section as illustrated in FigsJZl, st and 5, it is to be understood that the cross section may be other than circular without losing the advantages of my invention. For example the cross section may be a polygon, or a portion of a circle or polygon. Instead of having a clll'YCtl outlinefrom E toward E as shown in section in Fig. 1,, the section referred to may be a succession of dillerently shaped curves or straight lines. Or instead of a continuous shell the electrode may be made of a number of thin rods, water cooled or not as shown in Figs. (3, 7 and 8.

In Figs. (3 and? I have illustrated a modified form of electrode, that is, an electrode comprising a sectional shell or cage of conducting material.

In this case, in place of being circumfcrentially or peripherally continuous, the electrode material is disposed in the form of a plurality of separate bars, rods, wires, or other separate pieces E These connect at their outer ends with the ring I) such as described in connection with Fig. 1, having in mus for attaching electrical conductors to a source oi current and provided, if desired, with a core or space 0 and a cooling conduit l. The members l may be cast integral with the ring or llaugre l), or the flange B may be cast around the outer ends of the members it. or the members E may be otherwise suitably electrically and mw-hani ally connected to the flange I). The members E preferably converge toward each other at their inner ends and may tern'iinatc in a disk or plate of conducting material J. This member J may be ast integral with the members it) or the member J may be cast around the ends of the members E or any other suitable electrical and mechanical connection made between them. T he resistor K, Fig. 7, may be cast integral with the member J and be of the length and diameter shown in Fig. 6.

The refr ctory material of the furnace wall may be built around and between the members E, inside of the cage and outside of the cage and around and above the member 5 and around the solid resistor Thus in starting, the furnace molten material may be poured into the hearth H into contact with the upper end of the solid resistor R. The current is then turned on and finally the resistor R becomes molten and also the plate or disk J, as indicated in Fig. 6, in which case the apparatus is in condition for continued operation.

In Fig. 8 the flange or ring D is omitted and the members E extend independently beyond the furnace Wall and an electrical conductor may be connected to each one of them. In this case the members E are self cooling by their. projection beyond the furnace Wall.

In the forms illustrated in Figs. 6 to 8 in elusive, the electrode members E may be proportioned for mininnun loss as described in connection with Fig. l.

vVhen the mass M to be treated is of steel or iron or its alloys, the electrode E or E may be made of iron or steel; and when the mass M is of copper, brass, bronze or other copper alloys, the electrode E or F may be of copper. And when circumstances require it, the electrode E or E may be of carbon, graphite or of any other suitable material.

My structure of electrode has a further advantage that it affords large surfaces of contact at the connections between the outer end of the electrode and the leads to the source of current. And itis a further feature 01 advantage of my construction that the water cooling of the outer end of the electrode by means of the pipe or channel 1 can be brought well into the wall of the furnace with the result that when the melted metal has a low fusing point, it will not leak through cracks in the warm furnace wall but will freeze a considerable distance from the outer surfaces of the furnace wall. And by my construction the core 13 of refractory material in the inside of the shell or case electrode may be easily removed for repairs or" the electrode, or for rcachimz' the inner end of the resistor by drilling through the end of the electrode. And it is to be understood that. the electrode element's l of l ie's. (3 to 8 may vary in cross section between their outer and inner ends as is the case with the electrode l5 of Fig. 1, or they may otherwise vary in cross section.

\Yhat l claim is:

l. The combination with a Furnace electrode comprising a shell or cage ol conducting material whose conducting paths converge and unite, of a mass of conducting fluid, the current passed to or from said mass through said electrode passing through the union of said conducting paths of said electrode.

2. A furnace electrode comprising a shell or cage of conducting material diminishing in periphery between its ends and Whose conducting paths converge and unite.

The combination with a furnace electrode comprising a shell or cage of conducting material diminishing in periphery from its outer toward its inner end and Whose conducting paths converge and unite, of a mass of conducting fluid, the current passed to or from said mass through said electrode passing through the union of said conducting paths of said electrode.

4. A furnace electrode comprising a shell or cage of conducting material varying in thickness between its ends.

5. A furnace electrode comprising a shell or cage of conducting material increasing in thickness from its outer toward its inner comprising a shell or cage of conducting end.

6. A furnace electrode comprising a shell or cage of conducting material varying in periphery and in thickness between its outer and inner ends.

7. A furnace electrode comprising a shell or cage of conducting material diminishing in periphery and increasing in thickness from its outer toward its inner end.

8. A furnace electrode comprising a shell or cage of conducting material varying in periphery and thickness between its ends, the cross section of the shell remaining substantially constant.

0. A furnace electrode comprising a shell or cage of coinlucting material decreasing in periphery and increasing in thickness from its outer toward its inner end, the cross section of said shell or cage remaining substantially constant.

10. A furnace electrode comprising a shell or cage of conducting material, and an annular flange on the outer end of said shell.

11. A. furnace electrode comprising a shell or cage of conducting material, and a hollow flange at the outer end of said shell or cage.

12. A furnace electrode comprising a shell or cage of conducting material, a flange at the outer end of said shell or cage, and means associated with said flange for cooling the same.

13. A furnace electrode comprising a. hell or cage of conducting material, a flange at the outer end of said shell or cage, and means within said flange for conducting a cooling medium.

ll. A furnace electrode comprising a shell or cage of conducting material. a flange on the outer end of said shell or cage, and a mo est conduit for a cooling medium within said flange.

15. A furnace electrode comprising a shell or cage of conducting material, a flange on the outer end of said shell or cage, and a conduit for a cooling medium within said flange extending circumferentially of said I flange.

i said mass through a body of constricted con- .duetmg material forming a resistor.

1.8. In an electric furnace, an electrode material, and a mass of molten material in electrical communication with said elec trode, said shell or cage of conducting material oiiering such resistance to the current p 'ssed therethrough that said current raises said electrode at its inner end to a temperature substantially equal to the temperature of said molten material, whereby heat conduction from said molten material through said electrode is minimized.

19. In an electric furnace, an electrode comprising a shell or cage of conducting material, said shell or cage of conducting material having such resistance that the C R heat developed therein by current conducted therethrough shall be substantially equal to twice the heat conduction loss through said electrode when no current is passing therethrough.

20. In an electric furnace, a mass of molten material, an electrode comprising a shell or cage of conducting material whose conducting paths converge and form a union with each other, and a. resistor of molten material confined in a channel forming communication between said union and said mass of molten material.

21. In an electric furnace, a mass of molten material, an electrode comprising a shell or cage of crniducting material, means for producing a flow of said molten material, and a body of refractory material Within said shell or cage, said flowing molten nialerial impinging upon said refractory material.

22. In an electric furnace, a mass of molten material. an electrode comprising a shell or cage oi conducting material, a .l's'lsijfil ('(miined in a channel and forming li-leczricnl communication between said electrode and said mass of m lten material, said resistor having a cross section which is small with respect to the magnitude of current passed thcrethrough, whereby the pinch effect is produced in said molten material, and a body of refractory material within said shell or cage upon which said molteirmaterial impinges when moved by said pinch effect.

23. In. an electric furnace, a mass of molten material, an electrode comprising a shell or cage of conducting material, a resistor confined in a channel and forming a connection between said mass of molten material and said electrode, current passed through said resistor causing movement of the molten material thereinpand a mass of refractory material within said shell or cage upon which said flowing molten material impinges.

24. The combination with a composite furnace electrode comprising electrode elements separated at their outer ends and converging and uniting at their inner ends, of a mass of conducting fluid, the current passed toor'from said fluid mass through said electrode passing through the union of said electrode elements, a hearth for containing said mass of fluid material, and refractory material disposed between said separated electrode elements.

25. The combination with a composite furnace electrode comprising electrode elements separated at their outer ends and 'converging and uniting at their inner ends, of a mass of conducting fluid, the current passed to or from said fluid mass through said electrode passing through the union of said electrode elements, a hearth for containing said mass of fluid material refractory material disposed between said separated electrode elements, and means for causing movement of said conductin fluid, said refractory material receiving t he impact of said conducting fluid.

26. In an electric furnace, the combination with a furnace wall, of an electrode comprising a shell or cage of conducting material and a flange on the outer end of said shell or cage, said wall embedding said shell or cage and said flange.

27. In an electric furnace, a furnace wall an electrode comprising a shell or cage of conducting material, and a flange on the outer end of said shell. or cage, said flange partially'embedded in said wall and extending beyond the outer surface of said wall.

28. A furnace elect-rode comprising elec trode elements separated at their outer ends and converging and uniting at their inner ends.

29. A furnace electrode comprising a shell or cage of conducting material diminishing in periphery from its outer to its inner ends and whose conducting paths converge and unite at its inner end.

30. An electrode comprising a shell or cage of conducting material diminishing in periphery and changing in thickness from its outer toward its inner ends and whose I conducting paths converge and unite at its inner end.

31. A furnace electrode comprising a shell or cage of conducting material varying in thickness between the outer and inner ends and Whose conducting paths converge and unite at the inner end.

In testimony whereof I have hereunto affixed my signature in the presence of the two subscribing witnesses.

' CARL HERING.

Witnesses:

NELLIE EVANS, ELEANOR T. MCCALL.

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