JPH043882A - 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] <Industrial application field> The present invention relates to a DC arc furnace.

Arc furnaces are used for melting and refining steel materials. There are two types of arc furnaces: AC arc furnaces and DC arc furnaces, but in recent years, compared to AC arc furnaces, electrode consumption and power consumption are lower, and there is less need to replace electrodes due to wear. Direct current arc furnaces are attracting attention due to their advantages. There are several types of DC arc furnaces, but a typical type has one furnace top electrode placed in the internal space of the container and one or more electrodes attached to the bottom of the container. There is a method in which the steel material in the container is heated by an arc generated by applying a DC voltage between the container and the hearth electrode.

The present invention relates to an improvement of such a DC arc furnace.

<Prior art> Conventionally, an arc is generated by applying a DC voltage between one furnace top electrode placed in the internal space of a container and one or more hearth electrodes attached to the bottom of the container. This is a direct current arc furnace that heats the steel material in the container, and an electromagnet is attached to the container, and an alternating current magnetic field is generated by applying an alternating current voltage to a coil wound around the electromagnet to rotate the arc. has been proposed (Jitko Kosho 57-52623
), in the DC arc furnace, since the arc rotates, there is no damage to the inner wall of the container which is the furnace main body, and if the container which is the furnace main body is almost perfectly circular, there is no damage inside the container. It has the advantage of being able to uniformly heat steel materials.

However, in actual operation, the conventional DC arc furnace described above has problems with the arc due to the loading condition and properties of the steel in the container that is the furnace body, as well as the force directed in one direction caused by the wiring to the furnace body. If you want to direct the arc in a particular direction, you cannot direct the arc in that way,
In addition, if the container that is the furnace body is approximately oval in shape and extends to the tapping port side, the heating of the steel material on the tapping port side is delayed, so it ends up taking time to heat the steel material in the container. There is the issue of putting it away.

<Problems to be Solved by the Invention and Means for Solving the Problems> The present invention provides a DC arc furnace that solves the conventional problems as described above.

Therefore, the present invention provides an arc that is generated by applying a DC voltage between one furnace top electrode placed in the internal space of the container and one or more hearth electrodes attached to the lower part of the container. In the DC arc furnace that heats the steel material in the container, two pairs of electromagnets are disposed outside the container so that their respective magnetic fluxes are approximately orthogonal to the water flow, or their respective magnetic fluxes are approximately horizontally orthogonal to the container. Two pairs of electromagnets are installed, and a DC voltage is arbitrarily applied to each coil wound around the electromagnet, including the forward and reverse directions, and at least each magnetic pole of the electromagnet is The present invention relates to a DC arc furnace characterized in that an outer shell portion of a container facing the electromagnet or an outer shell portion of the container to which the electromagnet is attached is formed of a non-magnetic material.

In the present invention, since the outer shell portion of the container facing each magnetic pole of the two pairs of electromagnets or the outer shell portion of the container to which the two pairs of electromagnets are attached is formed of a non-magnetic material, the electromagnets When a DC voltage is applied to each coil wound on the TrLFii, the magnetic flux generated from the TrLFii stone does not escape along the outer shell of the container, so each coil generated from the electromagnet inside the container If the density of the composite magnetic flux is B, the arc current is the force, and the force is F, then the force due to the magnetic flux and the arc current, that is, the force known as Fleming's left hand rule, is B, the arc current is the force, and the force is F. A force represented by F=BXI can be applied inside.

The two pairs of electromagnets are arranged or attached so that their respective magnetic fluxes are almost horizontally orthogonal, and DC voltage can be arbitrarily applied to each coil wired to the electromagnets, including the forward and reverse directions. Therefore, the direction and density of the composite magnetic flux can be changed arbitrarily, and in the end, the force can be applied in any direction and with any magnitude.

Therefore, according to the present invention, the arc can be directed arbitrarily by the above-mentioned force, and when the container is approximately oval, the arc can be directed toward the tapping port to ensure uniformity of the steel in the container. By promoting heating, the steel material can be heated in a short time. If the magnetic poles of the two pairs of electromagnets are positioned below the lower end of the furnace top electrode and facing the internal space of the vessel, the arc can be directed more strongly, and each magnetic pole of the two pairs of electromagnets If the molten steel is located in a position facing the steel material (molten steel) inside, stirring of the molten steel can be more strongly promoted by applying a force in the same direction as the direction of the arc to the molten steel.

Hereinafter, the configuration of the present invention will be explained in more detail based on the drawings.

<Example> Fig. 1 is a vertical cross-sectional view (partially a front view) schematically showing an embodiment of the present invention, and Fig. 2 is a plan view schematically showing the embodiment, including its operating state. . The vessel 11, which is the furnace body of the DC arc furnace, includes an outer shell 21 and an inner wall 31 lined with the outer shell 21, and has a removable lid 11& similar to a warp. The outer shell 21 includes outer shell portions 21a, 21b, and 21c, which will be described later.
, 21d (however, the outer shell portions 2Lc and 21d are not shown; the same applies hereinafter) are made of iron, and the inner wall 31 is made of refractory material. The container 11 is loaded with steel material A, one furnace top electrode 41 is arranged in the interior space of the container 11 so as to be movable up and down, and one hearth electrode 51 is attached to the lower part of the container 11. , the furnace top electrode 41 and the hearth electrode 5
1 is connected to the DC power supply @61. Two pairs of electromagnets 71 and 72 are arranged outside the container 11 so that their respective magnetic fluxes are substantially horizontally orthogonal.
．． Each of the magnetic poles 72 is located at a position facing the inner space of the container 11 below the lower end of the furnace top electrode 41. Electromagnet 71.
72 are each wound with coils 81° and 82,
The coils 81.82 are each connected to a DC power supply device 62.63, and the DC power supply device fi62.63 can apply any DC voltage to each coil 81.82, including its forward and reverse directions. ing. And electromagnet 71
．． Four outer shell portions 21a, 21b, 21c, and 21d of the container 11 facing each of the magnetic poles 72 are made of nonmagnetic stainless steel, for example, austenitic stainless steel.

When the DC power supply device 62.63 applies any DC voltage including the forward and reverse voltage to the coil 81.82, the internal space of the container 11 below the lower end of the furnace top electrode 41 is charged, for example, as shown in FIG. The composite magnetic flux B of the respective magnetic fluxes XI and Yl due to the electromagnets 71 and 72] and the arc current (the first
The force F caused by the arc current flowing vertically in the figure)
1 acts, and the arc can be directed in accordance with the force F1.

FIG. 3 is a plan view schematically showing another embodiment of the present invention, including its operating state, similar to FIG. 2.

The container 12 is egg-shaped, and a tapping port 12b is opened at the lower part of the narrow side of the container 12, so that the magnetic fluxes of the respective magnetic fluxes are approximately horizontally orthogonal to the outside of the container 12. Two pairs of electromagnets 73 and 74 are arranged. Second
Although it is similar to the figure, when an arbitrary DC voltage is applied to the coils (not shown) wound around the two pairs of electromagnets 73 and 74 using a DC power supply (not shown), including the forward and reverse directions,
Container 12 below the lower end of the furnace top electrode (not shown)
For example, an electromagnet 7 as shown in the tiS3 diagram is placed in the internal space of
3.74, a composite magnetic flux B2 of the respective magnetic fluxes Xf and y2 and a force F2 due to the arc current act, and the arc can be directed in the direction of the tapping port 12b in accordance with the force F2.

FIG. 4 is a vertical sectional view (partially a front view) schematically showing still another embodiment of the present invention, similar to FIG. 1.

The container 13, which is the furnace main body of the DC arc furnace, includes an outer shell 22 and an inner wall 32 lined with the outer shell 22, and has a removable lid 13a similar to a pumpkin.

The outer shell 22 includes cylindrical outer shell portions 22a, 22b, 2, which will be described later.
2c and 22d (however, the outer shell parts 22c and 22d are not shown, the same applies hereinafter) are made of iron, and the inner wall 32 is made of refractory material.

The container 13 is loaded with steel material B, one furnace top electrode 42 is arranged in the inner space of the container 13 so as to be movable up and down, and one hearth electrode 52 is attached to the lower part of the container 13. The furnace top electrode 42 and the hearth electrode 52 are connected to a DC power supply 64. Two pairs of electromagnets 75 and 76 are attached to the container 13 so that their respective magnetic fluxes are substantially horizontally orthogonal, and each magnetic pole of the electromagnets 75 and 76 is located at a position facing the steel material B inside the container 13. Coils 83 and 84 (however, coil 84 is not shown, the same applies hereinafter) are wound around the electromagnets 75 and 76, respectively.
84 are connected to the respective DC power supplies 65, 66 (however, the DC power supply W66 is not shown, the same applies hereinafter), and the DC power supplies 65, 66 are connected to the respective coils 83.
Any DC voltage can be applied to 84 including the forward and reverse directions. Then, the four cylindrical outer shell portions 22a, 2 of the container 13 to which the electromagnets 75, 76 are attached.
2b, 22e, and 22d are made of nonmagnetic stainless steel.

The action of the force due to the composite magnetic flux of the two pairs of electromagnets 75 and 76 and the arc current is almost the same as in each of the embodiments described above, but in the embodiment shown in FIG.
This structure also allows for stronger stirring of (molten steel).

<Effects of the Invention> As is already clear, the present invention described above has the following advantages: the arc can be directed in any direction and with any force;
Particularly when the container is egg-shaped, the steel material in the container can be uniformly heated in a short period of time, and the stirring of the molten steel can also be promoted.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view (partially a front view) schematically showing an embodiment of the present invention, Fig. 2 is a plan view schematically showing the embodiment including its operating state, and Fig. 3 is a main view of the present invention. FIG. 4 is a plan view schematically showing another embodiment of the invention, including its operating state, similar to FIG. 2, and FIG. 4 is a longitudinal sectional view showing still another embodiment of the invention, similar to FIG. 1. (partial front view). 11-13...Container, 21.22...Outer shell 21
a, 21b, 22a, 22b - outer shell portion 31, 32...
・・Inner wall, 41.42・・Furnace top electrode 51.52・
... Hearth electrode, 61 to 65 ... DC power supply device 71
~76...Electromagnet, 81~83-...Coil A,
B...Steel patent applicant Daido Steel Co., Ltd. Agent Patent attorney Hiroshi Iriyama Figure 4 Figure 2

Claims (1)

[Claims] 1. Generated by applying a DC voltage between one furnace top electrode placed in the internal space of the container and one or more hearth electrodes attached to the bottom of the container. In a DC arc furnace that heats steel materials in the container using an arc, two pairs of electromagnets are arranged outside the container so that their magnetic fluxes are almost horizontally orthogonal, and each coil is wound around the electromagnet. DC voltage can be applied arbitrarily including the forward and reverse directions, and at least the outer shell portion of the container facing each magnetic pole of the electromagnet is formed of a non-magnetic material. DC arc furnace. 2. The DC arc furnace according to claim 1, wherein two pairs of electromagnets are arranged at positions where each magnetic pole faces the interior space of the container below the lower end of the furnace top electrode. 3. The arc inside the container is generated by applying a DC voltage between one furnace top electrode placed in the internal space of the container and one or more hearth electrodes attached to the bottom of the container. In a DC arc furnace that heats steel materials, two pairs of electromagnets are installed in the container so that their magnetic fluxes are almost horizontally orthogonal, and each coil wound around the electromagnets has a direct current voltage that is applied in the opposite direction. 1. A DC arc furnace, wherein at least an outer shell portion of a container to which the electromagnet is attached is made of a non-magnetic material. 4. The DC arc furnace according to claim 3, wherein two pairs of electromagnets are installed at positions where each magnetic pole faces the interior space of the container below the lower end of the furnace top electrode.