US1241574A

US1241574A - Regulating apparatus for electric furnaces.

Info

Publication number: US1241574A
Application number: US69044312A
Authority: US
Inventors: Wilfred Sykes
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1912-04-12
Filing date: 1912-04-12
Publication date: 1917-10-02
Anticipated expiration: 1934-10-02

Description

W. SYKES.

REGULATING APPARATUS FOR ELECTRIC FURNACES.

APPLICATION FILED APR. I2, 1912.

Patented Oct. 2, 1917.

3 SHEETS-SHEET I.

24 ZPL R O T N E V N WITNESSES l ATT'ORNEY w. sYKEs. REGULATTNG APPARATUS FOR ELECTRIC FURNACES.

APPLICATION FILED APR. l2. 1912.

Patented Oct. 2, 1917.

3 SHEETS-SHEET 2.

INVENTOR 5ATTRNEY W. SYKES. REGULATING APPARATUS Fon ELECTRIC Fu-RNACES.

APPLICATION FILED APR. l2. |932.

Patented Oct. 2, 1917.

3 SHEETS-SHEET 3.

WITNESSES: IN EN OR TTRN EY UNITED STATES PATENT oEEioE.

WILFRED SYKES, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

REGULATING APPARATUS FOR ELECTRIC FURNACES.

Specification of Letters Patent.

Patented Oct. 2, 1917.

To all whom it may concern:

Be it known that I, WILFRED Simms, a subject of the King of Great Britain, and a resident of Pittsburgh, in the county of A1- legheny and State of Pennsylvania, have invented a new and useful Improvement in Regulating Apparatus for Electric Furnaces, of which the following is a specification.

My invention relates to electric furnaces and it has special reference to such furnaces as are provided with movable electrodes.

The object of my invention is to provide a simple and durable means for automatically eilecting and maintaining the most advantageous position for the movable electrode of a furnace of the character above specified during the entire life of the e1ectrode.

Electric furnaces of the Hercult and Girod ty es, in which an electric arc is utilized flir producin heat, are equipped with vertically mova le electrodes which are frequently very large and heavy. In a large furnace of this character, a single electrode may weigh from two to three thousand pounds.

The above mentioned electrodes are adjusted by some suitable means which are operated either by individual driving motors or in oups by a single motor, clutches be ing utilized for independently operating the electrodes with the latter arrangement.

In order to secure the best results in operation, the position of the movable electrode must be constantly adjusted, and the usual methods of regulating these members have not been entirely satisfactory.

According to my present invention, I not only provide for the automatic adjustment of movable electrodes in response to the current traversing the arcs which are maintained in electric furnaces, but I also compensate for the variations in weight of the electrodes that are caused by their gradual consumption in service.

Figure 1 of the accompanying drawings, is a diagrammatic view of an electric furnace and its regulating apparatus arranged in accordance with my invention. Fig. 2 is a view, corresponding to Fig. 1, of a slightly modified system of furnace regulation embodying my invention. Figs. 3 and 4 are detail views illustrating modified compensating devices which may be substituted for the compensating apparatus of Fig. 1.

Fig. 5 is a view, corresponding to Fi 1 and 2., of another arrangement emboy ing my invention. Fig. 6 is a detail view of the compensating apparatus employed in the arrangement of Fig. 5, and Figs. 7 and 8 are views, corresponding to Fig. 1, of o ther arrangements embodying my invention. Fig. 9 is an elevation of the compensatin mechanism of Fig. 8.

Re eri-ing to Fig. 1 of the drawings, a furnace receptacle 1 is partially filled with ore 2, or other material to be reduced, which is .electrically connected to a supply circuit conductor 3 by means of a conductor 4. A movable electrode 5 is preferably suspended vertically above the furnace receptacle 1 into which its lower end extends. The electrode 5 is connected to a supply circuit conductoi 6 by means of a conductor 7.

The electrode 5 is largely supported by a counter-weight 8 to which it is operatively connected by cables or

chains

9 and 11 and

drums

10 and 12. The drum 10, upon which one end of the chain or cable 9 is wound, is cylindrical in form but the drum 12 is frusto-conical in order to compensate, as hereinafter pointed out, for variations in the weight of the electrode. The cable or chain 11 issecured to the electrode, extends over

sheaves

13 and 14 and is wound upon the frusto-conical drum 12.

The drums 10 and 12- are both lsecured to the Shaft 15 of a motor 16 which is so controlled as to effect a rotative movement of the

drums

10 and 12 in the one direction or the other, in response to variations in the current supplied to the furnace. The arrangement of parts is such that rotation of the motor 16 in the one direction winds the cord or chain 11 upon the drum-12 and raises the electrode 5, while rotation of the motor in the opposite direction pays out the cable or chain 11 and lowers the electrode 5.

Relatively small rotative movements of the drums are required to properly regulate the position of the electrode during any short period of time, but, by reason of the fact that the electrode 5 is gradually consumed in operation, the neutral position of 105 the drums about which the aforesaid small adjustments take place, is constantly changing. The surface of the frusto-conical drum `slsting lows:

12 is so proportioned that the torque produced by the weight 8 on the-shaft is always substantially counteracted. by .the torque exerted by the electrode 5. 1

The motor 16 1s, therefore, only called upon to exert a small continuous torque asthe conterweight and-to eect the aforesaid small rotative adjustments of the drum in order to maintain a substantially constant arc in the ace.

The motor 16 is a two-phase induction motor and has two airs of terminals 17 and 21 to which secon

ary windings

18 and 22 of

transformers

19 and 23 are respectlvely connected. The primary windings 20 and 24' of the

transformers

19 and 23 are respectively connected across one phase of the sugly circuit and in a series relation with t e furnace arc.

The operation of the apparatus is as fol- The motor 16 is so and proporltioned as to exert a continuous torque upon the shaft 15 which assists the weight 8 and tends to raise the electrode 5. When a predetermined` current traverses the furnace arc and the series transformer winding 24, the parts are in equilibrium, the torque exerted by the motor being then equal to the difference between the torque exerted by the electrode 5 and the weight 8. The torque of the motor varies as the current traversing the furnace arc, and the arrangement is such as to maintain this current substantially uniform. For instance, as the electrode 5 consumes, the distance between it and the molten material 2 increases, with the result that the current traversing the arc decreases due to the lengthening of the arc. The torque of the motor, therefore, decreases, and the weight of the electrode overpowers the combined torques exerted by the weight 8 and the motor. The electrode is thus lowered until the current is restored to the value which it is desired to maintain nearly uniform. On the other hand, if, for any reason, the current ofthe arc increases unduly, the torque of the motor increases correspondingly and, acting with the weight 8, raises.

As the electrode 5 is consumed, a greater length of the cableor chain 11 is paid off of the drum 12 and, consequently, by reason of the conical shape of the drum 12, the radius of the point of application of the forces exerted by the electrode upon the drum, is increased. It is, therefore, evident that the electrode may exert a constant torqu'e on the shaft 15, although it is continuously being consumed and its weight gradually reduced.

The mechanical arrangement and design of the parts shown in Fig. 2 is the same as `\tha.t shown in Fig. 1, and' corresponding parts are designated by the same reference characters. The weight 8 of Fig. 2, however, slightly overbalancesthe weight of the electrode 5 and the torque exerted .by the motor 16 tends to -raise the weight and lower the electrode.

The windings of the motor 16 are respectively connected in shunt relation to the -furnace arc, and to the terminals of a voltage transformer 25, which corresponds to the transformer 19 of Fig. l. The operation of this arrangement is as follows:

A condition of equilibrium is established when the torque exerted by the motor 16, added to the torque exerted by the electrode 5, is equal and opposite to the torque exerted by the weight 8. If, under these conditions, there is an increase in the voltage or tbe electromotive force dro across the furnace arc, the torque exerted y thev motor 16 will be increased and will produce such a rotative movement of the

drums

10 and 12 as to lower the electrode. Conversely, if the voltage o'r the electromotive drop across the furnace. are decreases, the torque exerted by the motor 16 will be diminished and the weight 8 will overhaul the electrode and raise it until conditions of equilibrium are restored.

The

drums

10 and 12 in the arrangements of Figs. 1 and 2, constitute what I shall term the compensating mechanism, but other structures and devices for accomplishing the same purpose may be substituted, for example: In Fig. 3 a single frusto-conical drum 26 is substituted for the

drums

10 and 12, both of the cables or

chains

11 and 9 being secured to it and wound upon it.

The arrangement of parts is such that, as the electrode is consumed and the cable or chain 11 is paid out, the point of application of the force exerted through the cable or chain -11 will be further removed from the center, while the same movement of the drum will gather a larger portion of the cable or chain 9, and the point of application of the force exerted by the weight 8 will be located at a lpoint nearer the center. By this means, the torques exerted by the electrode and the weight are both dlminished but are maintained equal.

In Fig. 4, a drum 27, corresponding to the drum 12, is substituted for the drum 10, and a drum 28, corresponding to the drum 10, is substituted for the drum 12. With this arrangement, the torque of the weight is diminished by the gradual shifting of the point of application of the force which it exerts upon the drum 27 to correspond to the decrease in torque exerted' by the electrode as its weight is diminished.

Referring to Figs. 5 and 6 of the drawings, the furnace reptacle 29 here shown, is provided with an electrode 30, having a rack projection 31 with which a driving pinion 32 coperates. The pinion is secured to the shaft of a n xptor which is adapted to adjust the position of the electrode. A large portion of the Weight of the electrode is counterbalanced by a weight 34 to which it is connected by a cable or chain 35.

The' motor corresponds to the motor 16 of Fig. 1 and is correspondingly energized, so that it exerts a continuous torque tending to assist the weight in raising the electrode.

The cable or chain 35 extends over a sheave or pulley 36 and is preferably divided aud wound upon a frusto-conical drum 37 to which the ends of the divided cord are secured.

The form of the drum and the manner in which the cable ends are wound upon it are clearly shown in Fig. 6.

The arrangement of parts is such that the reduction in weight of the electrode is compensated for in a manner corresponding to that of the arrangement of Fig. 3.

Referring to Fig. 7, the arrangement of parts is similar in all respects to that of Fig. 1, and corresponding parts are designated by the same reference characters. The furnace, however, is supplied with energy from a single-,phase sourceof energy (not shown) through

conductors

38 and 39 and an adjustable reactance 40 is connected in circuit with one of the motor windings in order to secure a displacement of phase. The operation of the system is the same as that of Fig. l.

When it is desired to govern the positions of one or more inclined electrodes 41, as illustrated in Fig. 8 of the drawings, the friction between each electrode and its support 42 may be suiiciently great to prevent a free downward movement of the electrode by the attraction of gravity. In this case a rack projection 43, corresponding to the projection 31 of Fig. 5, is provided to mesh with a pinion 44 which is driven by an electric motor 45. A frusto-conical drum 46 is secured to the motor shaft 47 and a weight 48 is suspended from a cord or chain 49 which is wrapped about the drum 46 and is secured to it.

The cord or chain 49 is so wrapped or wound upon the drum as to tend to drive the motor shaft in such direction as to move the electrode 41 downwardly. The motor connections are such as to oppose the torque produced by the weight 48. The drum 46 is so shaped as to compensate for the decrease in weight of the electrode by reason of its natural consumption in operation. The operation ofthe system of Figs. 8 and 9 corresponds to that of Fig. 5.

It is evident that any of the compensating mechanisms illustrated may be adapted for use with any one of the arrangements shown, and that electric motors of other types may be substituted for -those illustrated.

I claim as my invention:

1. The combination with a pair of cooperating relatively movable members, one of which is gradually consumed, of means for compensating for the variations of weight in the member which is consumed, and means comprising said compensating means for automatically maintaining a predetermined relation between said members.

2. In an electric furnace, the combination with a movable electrode, a counterweight and an interposed rotatable member so formed as to compensate for the variations in weight of the electrode, of an automatic means for producing rotative movements of the rotatable member.

3. In an electric arc furnace, the combination with a movable electrode, a counterweight and an interposed rotatable member so formed as to compensate for the variations in weight of the electrode, of automatic means dependent upon the current traversing the arc for producing rotative movements of the rotatable member.

4. The combination with an electric furnace having a consumable electrode, of means for compensating for variations in the weight of the electrode as it is consumed, and means comprising said compensating means for automatically regulating the position of the said electrode relatively to the remainder of the furnace in accordance with variations of an electrical condi-tion within the furnace.

5. The combination with an electric furnace having a consumable electrode, of means for compensating for variations in the weight of said electrode, and an electric motor for automatically varying the position of the electrode relatively to the remainder of the furnace, the said motor being supplied with current that is dependent in value upon the current traversing the furnace arc.

6. The combination with an electric fur nace having a consumable electrode, of means for compensating for variations in the weight of said electrode as it is consumed, and an electric motor for automatically varying the position of the electrode relatively to the remainder of the furnace, the said motor being supplied with current proportional to that supplied to the furnace.

7. The combination with an electric furnace having a consumable electrode, and a counterweight therefor, of means for compensating for variations in the weight of the electrode as it is consumed, an electric motor for varying the position of the electrode relatively to the remainder of the furnace, and means for automatically con-trolling the said motor in accordance with varior variations in the wei ht of ling the said motor in accordance with variations in the amount of current traversing the furnace arc.

In testimony whereof, I have hereunto subscribed lmy name this 5th day of April, 15

' WILFRED SYKES. Witnesses: B. B. Hnms, MJC. MEnz.