US2517527A

US2517527A - Furnace electrode regulator

Info

Publication number: US2517527A
Application number: US498317A
Authority: US
Inventors: William E Moore
Original assignee: Delaware Engineering Corp
Current assignee: Delaware Engineering Corp
Priority date: 1943-08-12
Filing date: 1943-08-12
Publication date: 1950-08-01
Anticipated expiration: 1967-08-01

Description

1, 1950 w. E. MOORE 2,517,527

FURNACE ELECTRODE REGULATOR Filed Aug. 12, 1943 Am COMPRESSOR 14 v (r l 44 I l 1-5 3:

CHECK VA LV! All? COMFHESSGR I g 55 i REVERSIBLE PUMP INVENTOR WL'ZZz'aml? Moore Patented Aug. 1, 1950 UNITED FURNACE ELEC'lTlti-il William E. Moore,

is, Fa to ilelaware Engineering @orporation, c. corpora tion at Illelaware Application August 12, 71943, Serial Ne, @8317 7 Claims. ((Dl. 3l4-==6l) This invention relates to a furnace electrode regulator for electric arc furnaces of the type in which the position of the movable electrodes is automatically adjusted by means of a fluid separated regulator. The regulator is controlled by apparatus which responds to variations in the electric current supply to the furnace.

The variations of the electric current are employed through the medium of suitable apparatus to control the power supplied to a fluid operated motor the operation of which will cause the electrode to which it is connected to move toward or away from the metal charge in the furnace.

In many installations the weight of the electrode and electrode gear is quite considerable and various counter-balancing means have been used to cushion this weight so as to avoid shocks or application of undue weight on the electrode when it meets the furnace charge, and permit prompt movement of the electrode proportional to the change in the current and/or voltage of the electric power supplied to the electrode.

Most of these arrangements have been either complicated, expensive, and difllcult to maintain, or they have rendered unsatisfactory service, whereas the system I have invented requires relatively little equipment, alfords very satisfactory electrode control, is inexpensive and substantially trouble free.

One object of my invention is to provide an automatic regulator for the electrodes of an electric arc furnace which will ensure that a substantially constant supply of current or power is taken from the furnace electric supply system, and that the electrode is moved gently.

Another object is to provide apparatus which is operated by fluid power and which is susceptible to close control.

A further object is to provide an electrode control system which is simple in construction, durable, inexpensive to construct and operate, and which alfords a high load factor operation.

According to my invention, the electrode is moved by a fluid operated cylinder and piston which is automatically controlled response to variations in the power flowing through the electrode and the weight of the electrode and connected parts is balanced so that no great weight will be transferred to the electrode.

Broadly speaking my invention comprises a fluid motor operatively connected with a furnace electrode and adapted to move it to adjust the length of the arc, means controlled by the electric condition of the electrode current for controlling the operation of the motor, and balancing means for the electrode.

In the accompanying drawings in which I have shown for purposes of illustration only, certain preferred embodiments of the present invention.

Figure 1 is a diagrammatic elevation of one embodiment of my invention, and

Figure 2 is a diagrammatic elevation of another embodiment of my invention.

The drawing, Figure 1, shows an electric furnace Ill containing a usual charge ll of inetal and an electrode i2 connected to an electrode arm |3. The arm is insulated from and supported by a plunger or ram M which is slidably received in a fluid operated power cylinder id. The piston and cylinder arrangement is commonly referred to as a hydraulic servo-motor.

The cylinder is connected at its lower end by a pipe It to a control valve ll. The control valve is connected by means of a pipe ill to the lower end of an air cushion hydraulic tank is sometimes referred to as the pressure tank and by means of the pipe 20 to the lower end of another air cushion fluid tank 2| sometlmes referred to as the equalizing or balancing tank. The lower end of tank 2| is connected to the tank l9 by a pipe 22, which is provided with a pump 23 driven by an electric motor 24. A check valve 25 is located in the pipe 22 between the pump 23 and the tank IS.

The control valve ll includes a slide valve or piston 26 which is slidably movable to regulate the supply of liquid medium from tank l9 and pipe l8 to pipe I6 and cylinder |5 or the liquid exhaust from cylinder I5 and pipe Hi to pipe 20 and I prefer to so arrange the openings from the regulator to the pipes l6 and I8 so that the valve 26 may close both openings at the same time.

A suitable source of air under pressure for example an air compressor 21 supplies air at a convenient predetermined pressure, above the liquid in pressure tank I9, so that the tank is only partially filled with liquid such as a hydrocarbon oil over which is an air cushion. The compressor 21 keeps the air pressure at a desired level so that the liquid is under a pressure sufficient to overcome the weight, friction and inertia of the plunger or ram I4 and the supported equipment. The tank I9 has a sight gauge 28, and a valve controlled liquid supply pipe 29, connected to it.

A suitable source of air under pressure for example an air compressor 30 supplies air at a convenient pressure, above the liquid such as a hydrocarbon oil in tank 2| A sight gauge 3| and a valve controlled liquid supply pipe 32 is connected to the tank as shown. The pressure in tank 2| is suflicient to substantially counterbalance the weight of the Plunger I4 and the weight of the equipment supported thereby so that when the piston 26 is positioned to allow the flow of liquid from pipe I6 through the valve l1 and pipe 20 to be established, the liquid will flow from cylinder l5 to tank 2| and the plunger l4 and its connected electrode I2 will move slowly and gently downwardly.

The position of the piston 26 is controlled by an automatic regulator 33 which is actuated in accordance with the electric power supply to the asman? electrode is in a manner well known in the art. Typical of. such regulators are CRAQIS Amplidyne- Type Electrode Regulator for Arc FurnaoeCon- .trol (General Electric 00.), and the Automatic Current Regulator for Electric Arc Furnaces (Westinghouse Electric and Manufacturing Company). The construction and operation of such devices are well known. Suffice it to say that ii the electrode |2 approaches too'closely to the charge 1 the power, supply to the furnace will be' unduly high and the regulator will cause the piston 25 of valve ii to be' moved downwardly so as to permit liquid to pass from the pressure tank 29, pipe .18, valve ii and pipe B5 to the cylinder it and cause the electrode to be raised, thus lengthening the arc, until the power input is that desired, whereupon the piston 25 will be moved upwardly to shut off the flow from pipe 88. When the electrode is too far away from the metal charge, the current will drop and the regulator 33 will lift the piston 26 so as to allow fluid tov pass irom the cylinder i5 through the pipe it, valve ii and pipe to the equalizing tank 2| until the power input reaches the desired valve, whereupon the piston 26 is lowered so as to cut off the fluid discharge through pipe is.

when the liquid is being discharged into tank 2|, the level of the fluid in the tank will rise and operate the float valve switch 34 and thus start the flow of electric energy to the motor 24 which will operate pump 23 to force the liquid through pipe 22 and check valve to the high pressure tank I9. The flow to tank |9 will continue so long as liquid is moved from the cylinder l5 to the tank 2|.

Instead of using air compressors 21 and 30, any other source of air supply may be employed, for example the ordinary shop air supply, with suitable reducing valves. Suitable air pressures for example, may be about 200 p. s. i. on tank I9 and about 100 p. s. i. on tank 2| when the pressure in cylinder l5 caused by the pressure of supported parts is about 125 p. s. i.

It is also possible to elevate the tanks l9 and 2| so as not to require air pressure on top of the liquid, but even in this case the pump 23 will be required to force the liquid from the tank 2| at a lower level to tank |9 at a higher level.

In the drawing, Figure 2, there is shown diagrammatically an electric furnace 50. containing a usual charge 5| of metal, and an electrode 52 connected to an electrode arm 53.- The arm is insulated from and supported by a plunger or ram 55 which is slidably received in a hydraulic cylinder 55. The piston and cylinder arrangement is commonly referred to as a hydraulic servo-motor.

The lower end of the cylinder is connected by a pipe 55, a pump 51, and a pipe 58 to a pressure tank 59, which is partially filled with a suitable liquid, such as hydrocarbon oil. A source of air under suitable pressure, for example an air compressor 50, supplies air at a predetermined pressure to the top of the tank 59, thus making it an air cushion tank. A liquid supply valve-controlled pipe 6| is connected to tank 59.

The hydraulic pump 51 is a reversible pump and is driven by a reversible electric motor 52. The operation of this motor is in turn controlled by an automatic regulator 53 which is actuated in accordance with the electric current supply to the electrode 52.

The pressure on the liquid in the tank 59 is thatnecessary to balance the weight of the ram 54 and the structure supported by it, less friction; for example about 10 to p. s. 1. less is satisa factory so that the ram and connections will remain Just balanced and the electrode static when the pump is not running. with such a pressure it is necessary for the pump to supply only enough pressure in either direction, as the case may be, to circulate the fluid through the pipes at, and E58, and between the tank E9 and the servo-motor to cause the ram to move. When the pressure is so balanced the reversing motor pump 51 will have the minimum amount of work to do. It may pull down the ram by reducing the pressure in the cylinder 55 or it may increase the pressure in the cylinder so as to lift the ram and the connected electrode.

The direction of the pump action is controlled by the electric current supplied to the electrode 52 acting through the regulator E53. Typical of such regulators are CR4913 Amplidyne-Type Elec= trode Regulator for Arc Furnace Control, manuiactured by General Electric Company, and the Automatic Current Regulator for Electric Arc Furnace, manufactured by Westinghouse Electric and Manufacturing Company. The contruction and operation of such devices are well known and need not be described in detail here. It is sumcient to say that if theelectrode 52 approaches too closely to the charge 53, the power supply to the furnace will be excessive and the regulator will cause the motor 62 to drive the pump so as to force the fluid from the tank 59 to the cylinder 55, and lift the ram and electrode until the power input is such as to cause the current to the motor 52 to be cut ofi. When the electrode is too far away from the furnace charge the furnace current supply will drop and the regulator 63 will operate so as to cause the pump 57 to force the fluid to flow from the servo-motor to the tank 59, thus permitting the ram and electrode 52 to move downwardly, until the power input reaches the desired value, whereupon the pump will be stopped.

Instead of using air pressure above the liquid in tank 59, it is possible to elevate the tank so as to obtain sumcient pressure.

In both modifications, 2| and 59, respectively are pressure reservoirs normally maintained at a pressure insufficlent to effect positive operation of the servo-motors, l5 and 55 respectively. In

, each the pump is effective for altering the pressure relation in the line between the reservoir and the servo-motor. In Fig. 2 it does this directly, whereas in Fig. 1 it draws fluid out of reservoir 2| and returns it, through tank is and valve I! to the line at a higher pressure.

In the accompanying drawings, I have illustrated diagrammatically, an electrode regulating apparatus embodying my invention as applied to one of the electrodes of a well known electric arc furnace, it being understood that a similar regulating device may be associated with each of the other furnace electrodes.

While I have described certain exemplary embodiments of my invention, it is to be understood that various changes may be made within the scope of my claims.

I claim:

1. Apparatus for hydraulically controlling the movement of an electrode of an electric arc furnace, including a vertically movable piston connected to the electrode, a cylinder in which the piston is slidably received, a pressure tank containing fluid under pressure, a reversible fluid pump hydraulically connected to the cylinder and to the tank, means for driving said pump, and means responsive to the flow of electric power to the electrode for causing the pump to force the fluid to or from the cylinder and from or to the tank, and means for maintaining the pressure in the tank substantially constant.

2. An electric arc furnace comprising a vertically movable mounting, an electrode carried by the mounting and provided with means for supplying it with electric power input, a liquid column and telescopic confining means therefor positioned to support the mounting, means for imparting a substantially constant thrust to the column in opposition to the weight of the mounting and the electrode, a reversible rotary metering pump disposed between, and connected to, a source of liquid and the column and adapted when driven in one direction to supply liquid from the source to the column in order to augment the latter and effect raising of the mounting and electrode and when driven in the opposite direction to remove liquid from the column and thereby effect a lowering of said mounting and electrode, and means for driving the pump in either direction, controlled automatically in response to variations in said electric power input.

3. An electric arc furnace comprising a vertically movable mounting, an electrode carried by the mounting, a liquid column and telescopic confining means thereforpositioned to support the mounting, means for imparting to the column a lifting force of such magnitude as substantially to counterbalance the weight of the mounting and electrode, a reversible rotary metering pump disposed between, and connected to, a source of liquid and the column and adapted when driven in one direction to supply liquid from the source to the column in order to augment the latter and effect raising of the mounting and electrode and when driven in the opposite direction to remove liquid from the column and thereby effect lowering of said mounting and electrode, and a reversible electric motor for driving the pump in either direction, controlled automatically in response to variations in the arcing gap of the electrode.

4. An electric arc furnace comprising a vertically movable mounting, an electrode carried by the mounting and provided with means for supplying it with electric power input, a liquid column and confining means therefor positioned to support the mounting, a reversible rotary metering pump disposed between, and connected to, a confined liquid source and adapted when driven in one direction to supply liquid from the source to the column in order to augment the latter and effect raising of the mounting and electrode and when driven in the opposite direction to remove liquid from the column and thereby effect lowering of said mounting and electrode, means for driving the pump in either direction, controlled automatically in response to variations in said electric power input, and means in the form of a confined body of gas under pressure on the surface of the liquid source, for imparting a substantially constant thrust to the column in opposition to the weight of the mounting and electrode.

5. An electric arc furnace comprising a vertically movable mounting, an electrode carried by the mounting and provided with means for supplying lt with electric power input, a liquid column and confining means therefor positioned to support the mounting, means for imparting a substantially constant thrust to the column in opposition to the weight of the mounting and the electrode, metering pump means disposed between, and connected to, a source of liquid and the column and adapted when actuated in a certain manner to supply liquid from the source to the column in order to augment the latter and effect raising of the mounting and electrode and when actuated in a different manner to remove liquid from the column and thereby effect lowering of said mounting and electrode, and means for effecting actuation of said metering means in either manner, controlled automatically in response to variations in said electric power input.

6. An electric arc melting furnace comprising an electrode and mounting therefor, a confined liquid column positioned to support said electrode and mounting, means for imparting to the column a lifting force of such magnitude as substantially to counterbalance the weight of the electrode and mounting, and a liquid metering pump means for adding liquid to said column to raise the electrode and mounting and to remove liquid from said column to lower said electrode and mounting, said means being electrically responsive to variations in the arcing gap of the electrode.

7. Mechanism adapted to support and automatically adjust an arc furnace electrode and comprising a, vertically movable mounting provided with means for holding the electrode in a depending manner and having means associated therewith for supplying the electrode with electric power input, a liquid column and telescopic confining means therefor positioned beneath and to support the mounting, a closed tank having therein a partial filling of liquid and, in addition, a. body of gas on the surface of the filling and under a pressure, the magnitude of which is substantially the equivalent of the weight of the mounting and the electrode, pipe means extending between and connecting the column and the bottom portion of the tank, a reversible rotary metering pump disposed in said pip means and adapted when driven in one direction to supply liquid from the tank to the column in order to augment the latter and effect raising of the mounting and the electrode and when driven in the opposite direction to remove liquid from the column and thereby efiect lowering of said mounting and electrode, and means for driving the pump in either direction, controlled automatically in response to Variations in said electric power input.

WILLIAM E. MOORE.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 528,281 Wade Oct. 30, 1894 1,032,040 Atwood July 9, 1912 1,528,510 Ritz Mar. 3, 1925 1,774,213 Taglia Ferri .Aug. 26, 1930 1,909,659 Clapp May 16, 1933 2,201,483 Eklund May 21, 1940 2,251,290 Reed Aug. 5, 1941 2,296,734 Payne Sept. 22, 1942 FOREIGN PATENTS Number Country Date 222,950 Great Britain Oct. 10, 1924 432,835 France Oct. 13, 1911 808,363 France Nov, 14, 1936