JPH03181786A - Dc arc furnace - Google Patents

Abstract

PURPOSE:To shorten a time required up to a feeding-out of molten steel and save a consumed amount of electrical power by a method wherein a lower conductor and an upper conductor are arranged such that an electrode force for displacing them always at a specified direction against an arc may influence through an electrical current for use in generating the arc. CONSTITUTION:An arc A is deflected by an electrical current I for use in generating an arc flowing in a lower conductor 8 or an upper conductor 18. That is, the arc A may receive a deflecting force F1 by a magnetic flux generated by an electrical current flowing in the lower conductor 8, receive a deflecting force F2 by a magnetic flux of the upper conductor 18. The arc is deflected in a direction of a combined force F3 of these deflecting forces. In a furnace 1, the lower conductor 8 and the upper conductor 18 are arranged such that a direction of the force F3 may occupy a direction of a location 51 far from the upper electrode 12 in a present spacing 5. As a result, a sufficient amount of heat is supplied there and it is difficult to occur that a melting of raw material charged or loaded in that place 5a is delayed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a DC arc furnace, and specifically relates to a DC arc furnace whose furnace body has a non-perfect circular planar shape [Prior Art] A DC arc furnace is a DC arc furnace. A furnace bottom electrode is provided at the furnace bottom, and an upper electrode is disposed above the raw material storage space inside the furnace body.

A current for arc generation is supplied to the picture electrode. Then, an arc is generated between the upper electrode and the molten raw material charged into the storage space, and the molten raw material is melted by the heat of the arc.

[Problems to be Solved by the Invention] When melting is performed as described above, in a furnace where the planar shape of the furnace body is not a perfect circle, a part of the above-mentioned storage space is located higher than other parts. The distance from the electrode is far, so the amount of heat supplied from the arc to that location is small. Then, it takes a long time for the raw material to dissolve at that location.

When melting is carried out under such conditions, in order to complete the melting of the entire charged raw material for melting, the melting operation must be continued until the above-mentioned areas have been melted. Therefore, there are problems in that it takes a long time to tap the steel and the amount of power consumed until all the raw materials are completely melted increases.

Is the invention described above? This technique was developed to solve the problems (technical issues) of the tX technique, and when performing melting, the arc is constantly deflected toward a part of the area far from the upper electrode, thereby preventing the melting of that area. It is an object of the present invention to provide a DC arc furnace that can accelerate the melting of raw materials, thereby shortening the time until tapping and reducing power consumption.

[Means for Solving the Problems] In order to achieve the above object, the present invention takes the measures as described in the claims above, and its effects are as follows.

[Function] The bottom electrode and the upper fM3t are connected through the lower conductor and upper conductor.
' When the current for arc generation is supplied to ' s, the melted raw material and the upper part! An arc is created between the poles. The arc causes the melting M class to melt. Due to the electromagnetic force caused by the current flowing through the lower conductor and the upper conductor, the arc is constantly deflected to a location farther from the upper electrode than other locations in the raw material storage space within the furnace body. Therefore, sufficient heat is supplied to the melted raw material at that location, promoting melting.

[Example] An example of the present application will be described below regarding rmi. 1 to 3, reference numeral 1 denotes a direct current arc furnace, and an EBT tapping type furnace is shown as an example of a furnace in which the planar shape of the furnace body is not a perfect circle. That is, 2 is a furnace body whose planar shape is not a perfect circle. - As an example, the shape is as shown in FIG. The furnace body 2
The furnace is composed of a furnace bottom 3 and a furnace wall 4, and has a raw material storage space 5 for storing melted raw materials inside. 61i space 5
7 is a hearth bottom electrode attached to the hearth bottom 3, and 8 is a lower conductor with one end connected to the electrode 7. 9 is a numbered outlet located on one edge of the hearth bottom 3;
a is an opening/closing device for the tap 9; Next, IO is a furnace lid placed over the furnace body 2, and has an electrode hole 11 into which an upper electrode 12 is inserted. Only one upper electrode 12 is provided. Upper type Fi! 12 is supported by an electrode support mechanism 13 so as to be movable up and down. The electrode support mechanism 13 has a well-known configuration, with reference numeral 14 an electrode support, 15 an elevating device, 16 an electrode support arm, and 17 an electrode gripper. 1
Reference numeral 8 indicates the presence of an upper conductor (referred to as a support arm busbar) provided along the support arm 16, one end of which is connected to the upper electrode 12. Reference numeral 19 indicates the presence of the lower conductor 8, the upper conductor 18, and the like. These are flexible electric wires connected to each end. Next, reference numeral 20 indicates a transformer room, in which a power supply device such as a furnace transformer is provided, to which the lower conductor 8 and the upper conductor 18 are respectively connected via flexible wires 19. There is.

I: In the arc furnace having the above configuration, a power supply for generating an arc is supplied from the power supply device to the bottom electrode 7 and the upper pole 12 via the lower conductor 8 and the upper conductor 18. Then, the furnace bottom is placed between the pole 7 and the upper electrode 12, or the furnace bottom is placed between the pole 7 and the upper electrode 12.
An arc A is generated between the melted raw material 6 (for example, scrap) and the upper electrode 12, which are electrically connected to each other. The melted raw material is melted by the heat applied to the arc. When the melting of the melted raw material is completed and all of the melt becomes molten δ, the tapping port 9 is closed and tapping is performed.

When melting is carried out as described above, the arc A is deflected by the arc generating current (2) flowing through the lower conductor 8 and the upper conductor 18. First, the principle will be explained based on FIG. The current flowing through the lower conductor 8 and the upper conductor 18 generates magnetic flux around each conductor as shown at 61 and 82, respectively. The sum of these magnetic fluxes at the location of arc A is indicated by B. Further, the t flow of arc A is ■. When such a magnetic flux B reaches the arc 8, a force F given by F=IXB (B is the magnetic flux density) is applied to the arc A, as known from Fleming's left-hand rule. The arc A is deflected by the force F.

In the arc furnace I, as shown in FIG. subjected to the deflection force shown. Their deflection force Fl.

The resultant force of F2 becomes F3. Therefore, arc A has its force F3
deflected in the direction of In the furnace 1, the direction of the force F3 is the direction of a part of the storage space 5 indicated by the reference numeral 5a, that is, the direction of a part where the distance from the upper electrode 12 is greater than other places (in this example, the direction of the tap outlet 9). The lower conductor 8 and the upper conductor 18 are arranged so as to be oriented in the direction of . As a result, even if some of the locations 5a are far from the upper electrode 12b) and have a location condition where the amount of heat supplied from the arc A is small, a sufficient amount of heat is supplied there. be done.

Top like this! 45! Since a sufficient amount of heat is also supplied to some locations 5a far from ll), it is unlikely that the melting of the raw material charged to that location 5a will be delayed, and therefore all the melted raw materials charged to the space 5 will be Dissolution is accomplished in a relatively short time.

The strength of the magnetic flux that the current flowing through the lower conductor 8 and the upper conductor 18 exerts on the arc is determined by the well-known formula B=μm/2πL.
As can be easily understood from (here, L is the distance from the current to the arc, μ is the magnetic permeability, and r is the t current),
The t current near arc A is strong. Therefore, when designing the arrangement of the lower conductor 8 and the upper conductor 18, the symbol "a+
It is recommended to particularly consider the position and orientation of each conductor in the vicinity of arc A, as shown by +8a.

Deflection of the arc as described above is also beneficial in the following respects. That is, since the arc A is deflected toward a part far from the upper electrode 12 as described above, the arc A may not hit the furnace wall 4a (the furnace wall on the side opposite to the transformer) near the upper electrode. This can significantly reduce damage to the furnace wall 4a in that part (or the water-cooled panel in that part if the furnace wall is constituted by a water-cooled panel). As a result, productivity is improved and production costs are reduced.

[Effects of the Invention] As described above, in the present invention, by supplying current for arc generation to the bottom electrode 7 and the upper electrode 12, an arc A is generated between the melted raw material 6 and the upper electrode I2. generate,
Not only does the heat of the arc A have the effect of melting the melted layer N6, but in the case of the above-mentioned melting, a part 5a in the space 5 in the furnace body 2 is far from the upper electrode 12, and that part is always Even under conditions where the amount of heat supplied to the molten raw material decreases, the arc 8 can always be deflected in a certain direction, so by setting the direction of deflection in the direction of the partial location 5a, the arc 8 can always be deflected in the same direction. Sufficient heat can be supplied to the melted raw material at that location, which has the effect of promoting melting there. This has the advantage of shortening the time until the entire melting of the melted raw material is completed, shortening the time until tapping, and reducing the amount of power consumed until then.

Moreover, even if the arc 8 is deflected as described above, the deflection is performed by electromagnetic force caused by the current flowing through the lower conductor 8 and the upper conductor 18 to generate the arc, so separate equipment for deflection is required. It is economically viable to implement without

[Brief explanation of drawings]

The drawings show an embodiment of the present application, and FIG. 1 is a plan view, FIG. 2 is a sectional view taken along the line ■-■, FIG. 3 is a sectional view taken along the line ■-■, and FIG.
The figure is a diagram explaining the principle of arc deflection. 2... Furnace body, 5... Raw material storage space, 7... Hearth bottom electrode, 8... Lower conductor, 12... Upper electrode, I8...
・Top conductor, A...Arc. Fig. Fig. Fig. Cow Fig.

Claims (1)

[Claims] It has a furnace body with a space inside for storing melted raw materials and a non-perfect circular planar shape, and a furnace bottom electrode connected to a lower conductor is attached to the bottom of the furnace body. On the other hand, an upper electrode connected to the upper conductor is disposed above the space, and supplies current for arc generation to the hearth bottom electrode and the upper electrode through the lower conductor and the upper conductor. In a DC arc furnace in which an arc is generated between the molten raw material placed in the space and the upper electrode, and the molten raw material is melted by the arc, the lower conductor and the upper conductor are A direct current arc furnace characterized in that the electric current flowing through the conductor of the DC arc furnace is arranged so that an electromagnetic force is exerted on the arc to constantly deflect the arc in a fixed direction.