JPH06185866A - Dc electric furnace for melting and refining metal - Google Patents

Abstract

PURPOSE:To efficiently perform direct current arc melting operation in a relatively small installation area while displaying the full advantage of a direct current arc furnace. CONSTITUTION:In an electric furnace of the type which generates arc by a carbon electrode and an electrode on the bottom side of each furnace, the two furnaces 1a and 1b are located close to an electric chamber 3 and arranged in a manner wherein the axes of the furnaces connecting the positions of the electrodes and tap holes 10a and 10b intersect each other and a carbon electrode 4 common to the two furnaces is made freely rotatable and movable in the diametrical directions of the furnaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC electric furnace for metal melting and refining, and more particularly to a DC electric furnace having two furnace bodies and one power source.

[0002]

2. Description of the Related Art An AC three-phase type arc furnace has been generally used as an electric furnace for metal melting and refining typified by steelmaking, but a DC arc furnace has been developed and is in operation in recent years. This DC arc furnace has a carbon electrode that is dedicated to the cathode.
Since it is enough with a book, it is possible to greatly improve the electrode unit consumption, the electric machine efficiency and molten steel agitation are good, and the power consumption unit is also improved because there is little heat dissipation loss. The unit can be improved, the flicker level can be greatly reduced, and the noise is small.

[0003]

However, the DC arc furnace is different from the three-phase AC arc furnace in that the anode is installed on the bottom side of the furnace and the arc is generated by the carbon electrode of the cathode. Even if the electrode is air-cooled or water-cooled, it reaches the end of its life in a short period of time and must be replaced. In addition to the transformer for the furnace as the power supply equipment, the AD conversion equipment is required, so that the electric room becomes larger (more than twice the AC type). However, conventionally, the DC arc furnace has generally adopted a one-power-one-furnace system. For this reason, production stoppage occurs due to replacement of the bottom electrode, and if multiple units are used as a countermeasure against this, a space is required in the electric room for each arc furnace, so a large installation area is required as a whole, and the rectifier and electrode are also required. There is a problem that the transmission loss increases because the distance from

[0004]

SUMMARY OF THE INVENTION The present invention was devised to solve the above-mentioned problems, and its purpose is to provide the advantages of a DC arc furnace while being relatively effective. It is an object of the present invention to provide a DC electric furnace for metal melting and refining that can efficiently perform DC arc operation in a small installation area. In order to achieve the above object, the present invention provides an electric furnace of a type in which an arc is formed by a carbon electrode and a furnace bottom side electrode, in which two furnace bodies are provided at a position close to an electric chamber and at an electrode position and a tap hole. The two furnace bodies are connected to each other so that the axes of the furnace bodies are connected to each other, and a carbon electrode common to the two furnace bodies is supported so as to be rotatable and movable in the diameter direction of the furnace body.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an outline of applying the present invention to a DC electric furnace for steelmaking, and FIGS. 2 to 4 show the details. 1a, 1
Reference numeral b denotes a furnace body of two electric furnaces, which is installed in an abutment facility 9 which constitutes a working floor. These furnace bodies 1a and 1b are respectively the same as the known furnace bodies, and tap holes 10a and 10b, respectively.
And the slag outlets 11a and 11b are arranged 180-fold symmetrically with this, and the upper part is covered with the openable / closable furnace lid 2 alternately. A plurality of rotatable ladles 13 are arranged. The furnace lid 2 has a dust collecting duct 21. A furnace bottom electrode 13 as an anode is attached to the bottom of each furnace body 1a, 1b. The furnace bottom electrode 13 is optional such as a steel pin, and is cooled by a water cooling device or an air cooling device (not shown).

Reference numeral 3 denotes an electric room. As shown in FIGS. 1 and 3, in addition to the furnace transformers 30 and 30, the thyristor device 3 is provided.
1, 31 and DC reactors 32 and 32, and the conductor mechanism 3 from the DC reactors 32 and 32 is vertically provided on the front part.
3, 34 are pivotably mounted about a vertical axis. The lower conductor mechanism 34 is provided in each of the furnace bodies 1a and 1b, and the secondary conductor 340 is connected to the furnace bottom electrode.

Reference numeral 4 is a carbon electrode as a cathode, and 5 and 5 are furnace lid suspension opening / closing devices. In the present invention, one carbon electrode 4 is shared by two furnace bodies 1a and 1b and alternately used. . The electric chamber 3 is provided at a position close to the two furnace bodies 1a, 1b, and the two furnace bodies 1a, 1b connect the electrode positions and the tap holes 10a, 10b in plan view. The furnace body axes are arranged to intersect each other at an angle α. The carbon electrode 4 is supported by a single electrode supporting device 6, and is rotatable about a vertical axis and displaceable in the radial direction of the furnace body.

First, the furnace lid suspension opening / closing devices 5 and 5 will be described. In the abutment equipment 9, a plane arc shape is provided at a position close to the electric chamber 3 and on a line connecting the intersection of the furnace body axis and the electric chamber 3. Guide rails 91, 91 are laid, and the guide rails 9 are
The movable bases 7 and 7 are movably arranged on the movable bases 1 and 91 respectively by the drive mechanism 92, and the furnace lid suspension beams 71 are provided on the bases 70 and 70 which are erected on the movable bases 7 and 7, respectively. A furnace lid lifting mechanism 710 is provided on the furnace lid suspension beam 71, and the furnace lid 2 is suspended. Next, as the electrode support device 6, the abutment equipment 9 between the two mounts 70, 7
A swivel base 65 that is capable of swiveling around a vertical axis is arranged by a swivel drive mechanism 66 such as a gear, and the mast 6 is vertically movable on the swivel base 65 by a lower lift drive mechanism 60.
1 is erected, and an electrode arm 62 is horizontally provided on the upper end of the mast 61.
Is supported by a retainer 620 mounted on the free end of the electrode arm 62 so as to be pivotable about a vertical axis. A secondary conductor 330 connected to the conductor mechanism 33 is connected to the carbon electrode 4.

The electrode suspension arm 62 is movable (expandable) in the radial direction of the furnace body. Specifically, as shown in FIGS. 3 and 4, a cylindrical holder 63 is fixedly provided on the upper end of the mast 61, and the electrode arm 62 is slidably arranged on the holder 63 via a bearing 630. A rack 62a is provided in an arbitrary area such as a side surface of the electrode arm 62,
The holder 63 includes a gear 63a such as a pinion that meshes with the rack 62a and an actuator 63 that drives the gear 63a.
b is provided. Of course, it is not limited to the rack and gear system, and a telescopic structure exemplified by a hydraulic cylinder may be adopted. The mechanism for displacing the electrode suspension arm 62 in the radial direction of the furnace body may employ a method in which the swivel mount 65 is further mounted on the mount and the mount itself is movable left and right in FIG. In that case, the lower part of the pedestal may be configured as a trolley, and the movable table 7 may be provided with a guide rail extending in the left-right direction in FIG. 3 so that the gantry can be moved along the guide rail.

FIG. 5 shows a work cycle when the present invention is applied. One of the furnace bodies 1a is provided with a carbon electrode 4
While the furnace is set to be energized, the other furnace body 1b is being repaired, charged with raw materials, and preheated. When the refining in the furnace body 1a is completed, the furnace lid 2 and carbon The electrode 4 is moved to the furnace body 1b side, and energization and melting and refining are started. In the open furnace body 1a, tapping, repair,
Charging and preheating are performed sequentially.

The operation of the embodiment will now be described. When the drive mechanism 92 is operated, the movable table 7 is swung by the guide rail 91 at a position close to the electric chamber 3, whereby the furnace lid suspension opening / closing device 5 is connected. The electrode support device 6 moves between the two furnace bodies 1a and 1b. Then, the furnace lid elevating mechanism 7 is placed on the one furnace body 1a.
When 10 is operated, the furnace lid 2 moves up and down to open and close the upper part of the furnace body 1a or 1b. Further, when the lifting drive mechanism 60 is operated, the electrode arm 6 holding the carbon electrode 4 is held.
2 moves up and down, and the carbon electrode 4 moves in the thickness direction of the furnace lid 2. When the actuator 63b is operated, the gear 62b and the rack 62a cause the electrode arm 62 to expand and contract in the radial direction within the limit of the clearance with the electrode insertion hole of the furnace lid, thereby changing the set position with respect to the furnace bodies 1a and 1b.

In the present invention, the furnace bodies 1a, 1b and the electric chamber 3 are in a relational position in which they are closest to each other. For this reason,
The distance between the carbon electrode 4 and the furnace bottom electrode 13 with respect to the thyristor devices 31, 31 is shortened, and power transmission loss can be reduced. Further, in addition to the two furnace bodies 1a and 1b being close to the electric chamber 3, the furnace axes connecting the electrode positions and the tap holes 10a and 10b are arranged so as to intersect with each other. As a result, interference when opening and closing the furnace lid 2 can be prevented, and the ladle position at the time of tapping can be optimized, and further, work of sufficient area around the furnace body, especially on the slag side. The floors A and B can be secured. This is advantageous for blowing oxygen and repairing the hearth. Furthermore, since the arc tends to bend due to the induced current, the electrode position of the DC electric furnace is preferably set at a position slightly displaced from the center of the furnace body. When the same carbon electrode 4 is used alternately in the two furnace bodies, the electrode positions are not always similar positions. However, in the present invention, as described above, the electrode arm 62 supporting the carbon electrode 4 has the actuator 63.
Expansion and contraction is controlled by b. Therefore, the carbon electrode 4 can be accurately set at the optimum position of the two furnace bodies 1a and 1b according to the state of the arc.

[0013]

According to the present invention described above, in addition to the merits of the DC electric furnace, such as a drastic reduction in flicker, an improvement in the electrode unit consumption, an improvement in the power consumption unit, an improvement in the furnace refractory unit consumption, and a noise reduction. Since the furnace body is a single-power-source direct current electric furnace, the furnace bottom electrodes can be replaced in the two furnace bodies at different timings, and the production stop due to the replacement of the furnace bottom electrodes does not occur. In addition, since the furnace body axes connecting the electrode position and the tapping hole intersect with each other in the position close to the electric room, the electric equipment including the electric room is sufficient and the power transmission loss is reduced. It is possible to easily perform operations such as opening and closing the furnace lid, tapping steel, blowing oxygen, and repairing the hearth, which are indispensable for operation. Moreover, since the carbon electrode can be controlled to expand and contract in the radial direction of the furnace body, 2 It can be set to the optimum position for each furnace body and energized. As a result, the excellent effect that the electric refining can be performed alternately and efficiently by taking advantage of the two-furnace-one-power-supply method is obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing an outline of a DC electric furnace for metal melting and refining according to the present invention,

FIG. 2 is a plan view showing the same details,

FIG. 3 is a side view of the same,

FIG. 4 is a sectional view showing an example of an electrode position displacement mechanism in the present invention,

FIG. 5 is an explanatory diagram of a work cycle to which the present invention is applied.

[Explanation of symbols]

1a, 1b ... Furnace body, 3 ... Electric room, 4 ... Carbon electrode, 6
... Electrode support device, 10a, 10b ... Steel tap, 13 ... Furnace bottom electrode

Claims (1)

[Claims] 1. An electric furnace of a type in which an arc is formed by a carbon electrode and an electrode on the furnace bottom side, a furnace body connecting two furnace bodies at a position close to an electric chamber and connecting an electrode position and a tap hole. A DC electric furnace for metal melting and refining, characterized in that the shafts are arranged so as to intersect with each other, and a carbon electrode common to the two furnace bodies is supported so as to be rotatable and movable in the diameter direction of the furnace bodies.