JPH0679441A - Molten steel heating equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to a plasma torch for heating molten steel in a ladle, which is suitable even if the molten steel level in the ladle is significantly changed by discharging molten steel from the lower nozzle of the ladle. The equipment provides heating conditions. [Composition] A hemispherical plasma hood with a diameter smaller than the ladle inner diameter, and a plasma torch that penetrates the hemispherical inward from the top of the ladle to fix the torch and the hood together, and put the torch at the molten steel level. It is possible to follow. [Effect] Since the torch and hood can integrally follow a large change in the molten steel level in the ladle, the torch water cooling part is short,
In addition, since the side wall of the ladle is not exposed to the radiant heat of the plasma flame, it is possible to perform plasma heating with low equipment wear and high thermal efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for molten steel in a ladle.

[0002]

2. Description of the Related Art With the demand for steel materials, it has become widespread to carry out secondary refining of molten steel from a steelmaking furnace such as a converter or an electric furnace in a ladle. As ladle heating with a plasma torch is provided. For example, JP-A-59-143016 and JP-A-5-143016
No. 8-212220.

In the case of continuous casting of molten steel in a ladle and transfer to an ingot mold for subsequent processing, a plasma torch heating means is used to keep the hot water warm.
No. 654 publication.

However, in all cases, the hood is mounted on the ladle head, and the height position of the hood is almost constant. Moreover, in the case of refining, the molten steel level is constant, and the distance between the molten steel and the torch is also constant.

[0005]

However, when the molten steel of the ladle is continuously cast or poured into the ingot, the molten steel level is lowered, and accordingly, the torch penetrating the cover of the ladle must be lowered to the molten steel level. .

The level of the molten metal changes greatly from the time when the molten steel in the ladle is full to the time when the molten steel is empty, and in the case of a large ladle, it changes by 3 to 4 m. The plasma torch should be properly spaced above the surface of the bath.

In this case, since the hood is fixed, when the tip of the torch is lowered, the length of the water-cooling portion of the torch becomes several meters, the equipment cost increases, and the heating efficiency lowers.

Further, when the level of the molten metal is lowered, the heat generated by the plasma arc is transferred to the inner wall of the ladle, which causes the bricks to be damaged by the heat and causes a decrease in the thermal efficiency. The present invention is intended to eliminate such drawbacks.

[0009]

The present invention solves these drawbacks. That is, a plasma torch with an elevating device that moves the torch up and down according to the molten steel level in the ladle is equipped with a hemispherical plasma hood having a diameter smaller than the ladle inner diameter, and the plasma torch is hemispherical from the top. Molten steel heating device in a ladle that allows the torch and hood to be integrally fixed by projecting through the inside of the shape and allowing the torch to follow the molten steel level, and in the above device, an inert gas is blown from the bottom of the ladle. It is a molten steel heating device in a ladle.

[0010]

The operation will be described with reference to FIG. The ladle 1 has a structure in which the diameter of the upper part is larger than the diameter of the lower part, the plasma torch 2 is provided through the hemispherical hood 3, and the plasma torch 4 has a tip of the torch approximately 10 to 50 cm from the lower edge of the hood. It is located at the top and fixed to the hood 3. This distance can be changed, and the optimum value of the use condition of the torch is selected.

As for the length of the torch, the torch 2 is a hemispherical hood 3
It may be a little shorter than the lower end of the hood in the part that penetrates.
Alternatively, the length may be a little longer than the hemispherical shape 3 on the upper part of the torch 4. The inside of the hemispherical hood 3 is lined with a refractory material 7, has an exhaust port 8 and discharges gas from the inside. A handle 6 is provided on the upper part of the hemispherical hood 3, and the handle is supported by a support tube 7 and the support tube 9 is a torch lifting device 4
Attached to the arm 10. The upper end of the plasma torch is attached to the torch lift 4 so that the distance between the torch front end and the melt level can be adjusted. The hemispherical hood 3 has an outer diameter smaller than the inner diameter of the bottom of the ladle 1.

Therefore, by raising and lowering the hemispherical hood integrally with the torch, a constant optimum heating chamber shape can be obtained regardless of the ladle level, and the heat of the plasma arc lining the ladle regardless of the ladle molten steel level. It has the effects of not acting on bricks, the smallest torch required regardless of the molten steel level in the ladle, and the minimum length of the water-cooled portion.

Reference numeral 5 in the drawing denotes a sliding nozzle. Next, FIG. 2 is a ladle having the torch and the hemispherical 3 hood of FIG. 1 having a plug 11 at the bottom, and injecting an inert gas (argon or N ₂ ) from the molten metal in the ladle at about 200 liters / minute. , Remove the slag on the molten metal. When molten metal appears on the surface of the ladle, lower the plasma torch and hood. The surface of the molten metal is irradiated with plasma and gas is blown from the bottom of the ladle to agitate the molten metal, and the heat of the plasma is transferred to the entire molten steel.

[0014]

The present invention is provided with a hood having a hemispherical shape smaller than the inner diameter of the ladle, and the plasma torch is penetrated and protruded from the top of the hood to the inside of the hemispherical shape so that the hood and the torch are integrated and the molten steel level surface in the ladle It is a plasma torch for heating molten steel in a ladle with an elevating device adapted to follow.

[Brief description of drawings]

1 is a partial sectional view of a steel transfer ladle and plasma according to the present invention.

FIG. 2 is an explanatory cross-sectional view including a plug according to the present invention.

[Explanation of symbols]

 1 Ladle 2 Plasma torch 3 Hemispherical hood 4 Torch lifting device 5 Sliding nozzle 6 Hood hanger 7 Hood refractory 8 Gas discharge port 9 Support rod 10 Arm 11 Refractory 12 Molten metal 13 Plug 14 Slag

Claims (2)

[Claims] 1. A molten steel heating device in a ladle having an elevating device for vertically moving a plasma torch in accordance with the molten steel level in the ladle, comprising a hemispherical plasma hood having a diameter smaller than an inner diameter of the ladle, and having a top portion. A molten steel heating device in a ladle in which the plasma torch is further projected through the inside of the hemisphere and the torch and the hood are integrally fixed so that the torch can follow the molten steel level. 2. The molten steel heating device in a ladle according to claim 1, wherein an inert gas is blown from the bottom of the ladle.