JPS6020495A - Ac and dc arc furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arc furnace used for melting and refining metals, and more particularly to a dual-purpose sintering furnace that can emit an arc using both alternating current and direct current power sources.

There are two types of arc furnaces: AC arc furnaces (generally AC three-phase arc furnaces) and DC arc furnaces, each of which has advantages and disadvantages.

For example, in an AC three-phase arc furnace, there is no need for opposing poles, and by inserting the three electrodes from both sides of the furnace, the electric current can be generated immediately.
It has advantages such as y U If 2 batting effect 4 hits),
The 3-phase arc is bent outward due to the 41J mutual electromagnetic force and released! 1
Disadvantages include a large amount of heat, low thermal efficiency, local IQ peaks on the furnace wall due to arc bending, large amount of electrode wear, loud noise, and severe flicker.

On the other hand, in a DC arc furnace, the upper structure of the furnace is in the cylinder because there is a water electrode, the arc does not bend and damage the furnace wall, there is less electrode wear, there is less noise, there is less flicker, etc. However, since the other electrode of the arc furnace is installed directly at the bottom of the furnace, the energization state between the electrodes at the time of starting is II7.
9ri 1FIJ electrode is required until Katadome reaches C'! However, during continuous operation, it is necessary to take measures such as leaving hanging lagoons necessary for electrode formation during the previous tapping process, which reduces the actual cost of the furnace. There were 9.0 places where the stirring effect was low.

In view of the above-mentioned circumstances, the present invention aims to improve the operability of the arc furnace by making use of alternating current and direct current arcs and taking advantage of the respective advantages of the alternating current arc furnace and the direct current arc furnace. It is something to do.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.
In this embodiment, three-phase alternating current is used instead of alternating current.

Three wooden electrodes 2a, 2J2c are installed above the furnace 1 (), and each electrode 2a, 2b, 2c is connected to the secondary winding 4a, 41+, 4c of the AC power supply ([・lance) 3]. . In addition, the secondary windings 4a, 4b, and 4c are star-coupled at point A, and one pole of 1λ6 is connected to the point via AC 1 and 5. A furnace bottom electrode 7 arranged at the bottom of the furnace 1 is connected to one pole.

Further, in the figure, 8 indicates a rectifier, and 9 indicates a transformer.

In the above configuration, when the DC type 'IfAG is not energized and the AC power source 3 is energized, three-phase alternating current flows through the molten material in the furnace, the molten metal, and the electrodes 2a, 2b, and 2c with point Δ as a neutral point. , a three-phase AC arc is applied to the lower ends of the electrodes 2a, 2b, and 2c, and the AC power source 3 is energized! i” energize DC power supply 6
Then, a direct current is applied between the electrodes 2a, 2b, 2c and the hearth bottom electrode 7, and light is generated at the end of the set 2a, 213.2 (DC).

The change 1β between the alternating current shear and the free current arc is 6 lightning & 3°6
It is easy to change the energizing voltage to one side and increase the voltage to the other side.
(IF and P are available. Power 81: Installing a switch to change the i) is also an iJ function, but the large current C
'If the capacity of the switch is limited to 4 hours, the ON and OFF operations must be done in stages, such as turning on and off from 1 to 4, and cutting off the arc. CG, no.

And LZ,! /ri ffJJ ff'7 Ll
311 Interchange? fiffi k: , l, -J T 7-
'/ Heating is done without making noise, and when warm air is generated at the bottom of the furnace, the AC voltage is lowered and the DC type LIE is switched to -L. Stirring the molten metal with an alternating current arc
I do.

Figure 2 shows another embodiment, in which a DC power source is connected to each lightning bolt 4! i2a, 2b, 2c and AC power supply (transformer) 3-2
It is designed to be connected between the next windings.

As shown in FIG. 2, it is no longer necessary to pass a direct current through the lances 1 to 3, thereby reducing the series electrical resistance.

Further, FIG. 3 shows still another embodiment 'CA3' in which the electrodes are made of two pieces of wood 11a and 11b and an arc is generated by single-phase alternating current and direct current. In addition, in FIGS. 1 to 3, a method of controlling the DC voltage using lances 9 is shown for convenience. (IC1
Control is also possible.

As described above, according to the present invention, (1) no special electrode is required for starting;
) Direct current arc and alternating current during refining)? (g) The volume inside the furnace can be used without wasting it, (f) The large number of electrodes (゛, melting imbalance inside the furnace). (V) Combines the advantages of a DC arc furnace and an AC electric arc furnace.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment 141 of the present invention, and FIGS. 52 and 3 are explanatory diagrams of a third embodiment of the present invention. 2 a, 2 b, 2 c Lit electric rods, 3 is an AC power supply, 5 is a reactor 1, 6 is a DC YX source, 1 is a bottom voltage source. Patent application: Ishikawajima Harima Φ Industrial Co., Ltd.

Claims (1)

[Claims] 1) Bottom 7u pole and 2 or more arc lightning) 4 (to the right,
The feature is that an AC power supply is connected so that an AC current is passed between the arc electrodes, and one pole of the DC power supply is connected to the bottom electrode, and the other pole is connected to the arc electrode via a reactor. AC/DC arc furnace.