JPH0216988Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Field of Industrial Application) The present invention relates to an improvement in a refining apparatus in which the entire ladle is housed in a vacuum container and powder or gas is blown into the ladle under reduced pressure. (Prior Art) VOD is well known as a refining device in which the entire ladle is housed in a vacuum container and gas is blown into the ladle under reduced pressure. Furthermore, recently, it has become common practice to inject powder into molten steel along with large amounts of gas. In these vacuum refining apparatuses, the ladle is housed in a vacuum atmosphere, and there is no heat dissipation due to air convection, so the ladle shell temperature is higher than when it is not in a vacuum atmosphere. Furthermore, when the hot exhaust gas stream comes into contact with the ladle shell, the shell will reach the permissible temperature (normally
(approximately 400℃) or higher. To prevent this exhaust gas flow from contacting the ladle shell, the exhaust duct is typically located above the top of the ladle. In this case, the height of the vacuum chamber in which the ladle fits is greater than (ladle height + exhaust duct height), and because the height is high, it is difficult to store the ladle in the vacuum chamber than the hanger beam of the crane. It is necessary to increase the inner diameter of the chamber, and therefore the internal volume of the vacuum chamber is enormous, and accordingly, the vacuum evacuation device also needs to have a large capacity. As an improvement regarding the vacuum chamber inner diameter, there is an example in which the crane hook is extended to make it possible to set a ladle without putting the hanger beam into the vacuum chamber, thereby reducing the vacuum chamber inner diameter. No improvements have been made. (Purpose of the invention) The present invention is a vacuum refining device that solves all of the above problems.
It is an object of the present invention to provide a vacuum refining device whose height can be reduced, which is therefore compact and inexpensive, and whose exhaust device can also be downsized. (Structure of the invention) The feature of the invention is that an exhaust duct is provided so that the lower end of the duct is lower than the upper end of the housed ladle, and that an exhaust duct is installed at the entrance of the exhaust duct. A guide is provided which has an opening at a portion higher than the level of the upper end of the pan and which has a gas flow path not smaller than the cross-sectional area of the exhaust duct. Hereinafter, the present invention will be explained in detail based on illustrated examples. FIG. 1 is a plan view of a refining apparatus according to the present invention, and FIG. 2 is a conceptual diagram as viewed from the longitudinal cross-sectional direction. In the figure, 1 is a vacuum vessel, 2 is an exhaust duct attached to the outer surface of the vacuum vessel, 3 is a ladle, 4 is a hanger beam of a crane, 5 is a crane hook, and 6
is a guide attached to the inside of the vacuum container facing the entrance of the exhaust duct. 1 and 2 show the ladle 3 installed in the vacuum container 1 using a crane. The exhaust duct is arranged so that the lower end 12 is at a low position. Therefore, when the top cover (not shown) of the vacuum container 1 is removed, the top end 13 of the vacuum container 1 can be kept at a height somewhat higher than the top end 11 of the ladle 3. There is no big difference between the height level of the upper end 11 of the ladle 3 and the upper end 11 of the ladle 3. Therefore, it becomes possible to take in and out the ladle 3 without putting the hanger beam 4 of the crane into the vacuum vessel 1, or in other words, without bringing the hanger beam into contact with the upper end 13 of the vacuum vessel. The volume of the vacuum vessel 1 is extremely small compared to a vacuum vessel with an inner diameter larger than the length of the vacuum vessel and a height equal to the height of the ladle plus the height of the exhaust duct. In addition, in order to prevent the iron skin of the ladle 3 which is close to the inlet 14 of the exhaust duct 2 from being locally heat-lossed due to the flow of exhaust gas toward the exhaust duct inlet 14, the upper end 11 level of the ladle is lowered. A guide 6 is provided which has an opening 15 at a higher portion and a gas passage 17 not smaller than the cross-sectional area of the exhaust duct so that the exhaust gas flows at a position above the ladle 3. This guide 6 is made of, for example, a thin steel plate coated with fire-resistant castable on both sides, and is provided so as to surround the inlet 14 of the exhaust duct 2, and the guide 6 is at least at the level of the upper end 11 of the ladle 3. The parts corresponding to the following are fixedly installed on the inner wall of the vacuum container 1 and sealed to prevent gas from flowing. Furthermore, the gas flow path 17 of the guide 6 is not smaller than the cross-sectional area of the inlet of the exhaust duct 2, that is, the gas flow path does not restrict the exhaust gas flow. Therefore, the exhaust gas can be smoothly sucked through the opening 15 at a position above the upper end of the ladle 3, the exhaust gas flow will not stagnate, and the ladle will not be locally damaged by heat loss due to the exhaust gas flow. (Operation of the invention) The operation of the apparatus of the invention having the above configuration will be described with reference to the embodiment shown in FIG. A ladle 3 containing molten steel 7 is placed into a vacuum container 1, and an upper lid 8 is attached. Further, an injection lance 10 is inserted through an opening 9 formed in the upper lid 8 to perform refining. In this case, the exhaust gas flowed smoothly in the direction of arrow G through the guide 6 without locally causing heat loss to the iron skin of the ladle 3. (Example) Examples of the vacuum refining apparatus of the present invention are shown in Table 1 together with conventional examples.

[Table] (Effects) As described above, according to the device of the present invention, even if the exhaust duct 2 is provided so that the lower end 12 of the exhaust duct 2 is below the upper end 11 of the ladle, it is lower than the level of the upper end of the ladle. A guide 6 having an opening in a high part and having a gas flow path not smaller than the cross-sectional area of the exhaust duct.
Since the exhaust gas flow does not come into contact with the iron skin of the ladle 3, the exhaust gas is smoothly introduced into the exhaust duct 2, and there is no heat loss to the iron skin.
Furthermore, the above arrangement position of the exhaust duct makes it possible to lower the height of the vacuum chamber 1, and by lowering the height of the vacuum chamber, the crane hook 5
The length remains the same as before, and the ladle 3 can be handled without putting the hanger beam 4 into the vacuum chamber 1. Also, since the hanger beam 4 does not need to be put into the vacuum chamber 1, it is possible to handle the ladle 3. The inner diameter of the ladle 3 can be made the minimum diameter that the ladle 3 can handle, and both the diameter and height of the vacuum chamber can be made much smaller than conventional vacuum chambers. Therefore, the reduced pressure refining apparatus of the present invention has the advantage that it is compact and inexpensive, and the attached exhaust device can also be small.

[Brief explanation of the drawing]

Figure 1 is a plan view of the vacuum refining equipment of the present invention, Figure 2
The figure is a conceptual diagram as seen from the longitudinal cross-sectional direction, and FIG. 3 is a conceptual diagram showing the operating state of the vacuum refining apparatus according to the present invention. 1... Vacuum container, 2... Exhaust duct, 3... Ladle, 4... Crane hanger beam, 5... Crane hook, 6... Guide, 8... Top lid, 11
...Top end of ladle, 12...Bottom end of exhaust duct, 1
4... Inlet of exhaust duct, 15... Opening of guide, 17... Gas flow path.

Claims (1)

[Scope of utility model registration request] In a refining device that stores a ladle inside and blows powder or gas under reduced pressure, an exhaust duct is provided so that the lower end of the exhaust duct is lower than the upper end of the stored ladle, and the exhaust duct is 1. A vacuum refining device characterized in that a guide is provided at the inlet, the opening being higher than the level of the upper end of the ladle, and the guide having a gas flow path not smaller than the cross-sectional area of the exhaust duct.