JPS61213311A - Blowing lance for converter - Google Patents

Abstract

PURPOSE:To suppress the wear and deformation of a nozzle provided to the bottom end of a lance body by providing a molten metal-proofing wall projecting downward from the bottom end face of the nozzle along the circumferential edge of said bottom end face and providing a ceramic guard which covers the bottom end face of the nozzle in the region enclosed by the molten metal- proofing wall. CONSTITUTION:The blowing lance for a converter is inserted into the converter and blows gaseous oxygen from the bottom end thereof toward the molten steel in the converter. The molten metal-proofing wall 15 which projects downward from the bottom end face of the nozzle 10 installed to the bottom end of the lance body is provided along the circumferential edge of the bottom end face. The ceramic guard 16 which covers the bottom surface in the region enclosed by the wall 15 is provided to said region and is pinned 17 to the wall 15 via ceramic fiber seals 18.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a lance that is inserted into a converter furnace and blows molten steel by blowing oxygen gas onto the molten steel in the furnace. This invention relates to an extended converter blowing lance.

[Prior Art] In converter refining, as shown in FIG.
The molten steel 1 inside is blown by oxygen gas through a lance 3. A vertically movable skirt 5 is installed above the furnace mouth 4 of the furnace body 2, and a lower hood 6 and an upper hood 7 are installed above the skirt 5. The converter gas is guided by the skirt 5, the lower hood 6, and the upper hood 7 and led to the converter gas recovery device. A copper nozzle is attached to the lower end of the lance 3, and cooling water is passed through the nozzle to cool it. On the bottom of the nozzle,
For example, four discharge holes are formed, and oxygen gas is blown onto the molten steel below through these discharge holes.

By the way, high-pressure oxygen gas is present in the converter 2, the temperature is extremely high, and a large amount of FB steel and slag grains are floating. Then, as a result of the molten steel and slag particles adhering to the lance, the molten steel and slag solidify and the base metal covers the entire nozzle.

Then, the metal will fall during blowing, or new metal will be deposited on top of it while blowing is repeated.

[Problems to be Solved by the Invention] This conventional lance for converter blowing has problems in that the lower surface of the nozzle is thinned and the discharge hole is deformed. This phenomenon can be considered as follows. The surface of the molten steel and slag adhering to the nozzle is in a molten state due to the radiant heat of the molten steel, and the surface of the lower surface of the nozzle is softened in the area where the cooling ability is low. After blowing, when the lance is raised, the deposits on the nozzle are rapidly cooled and turned into metal. At this time, the metal itself contracts, and
This contraction causes the nozzle surface to also contract, and furthermore, in the softened portion of the nozzle, the base metal is fused and fixed to the nozzle.

In this nozzle softened part, new metal is further deposited on the fixed metal in the next blowing process, and the increased weight of this metal makes it impossible for the nozzle softened part to support the metal. The base metal and the nozzle surface portion to which the base metal is fused fall. By repeating such a phenomenon, the bottom surface of the nozzle becomes thinner. Moreover, when the bottom surface of the nozzle is thinned, the cooling capacity of that part is reduced, and therefore the base metal is formed to be thick. Then, in this part, the metal is more likely to fall, and the nozzle becomes thinner.

In addition, local thinning of the nozzle causes an imbalance in the thermal load on the nozzle, and furthermore, there is a problem that the nozzle discharge hole is deformed as a result of thermal expansion and contraction of the base metal.

[Means for Solving the Problems] The present invention has been made in view of the above circumstances, and it is possible to prevent base metal from adhering to the nozzle of the lance and to suppress wear and deformation of the nozzle. The purpose of the present invention is to provide a lance for converter blowing that can be used in a converter.

The converter mouth metal removal device according to the present invention is installed at the lower end of the lance main body in a converter blowing lance that is inserted into the converter and sprays oxygen gas onto molten steel in the furnace from the lower end of the lance. A barrier 1 wall that protrudes downward from the lower end surface along the periphery of the lower end surface of the nozzle; a ceramic guard that covers the lower end surface of the nozzle in an area surrounded by this leakage prevention wall; and a fixing means for fixing to a wall.

[Embodiment] FIG. 1 shows a nozzle 10 attached to the lower end of the main body of a converter blowing lance according to an embodiment of the present invention. Nozzle 1
0 is outer tube 11 and inner! ! 12 , and a discharge hole 14 opening in the lower surface 13 of the nozzle 10 is formed so as to communicate with the inside of the inner tube 12 . Such a discharge hole 14 is, for example,
Four are provided on the lower surface 13 of the nozzle 10.
The openings are evenly spaced. Oxygen gas is supplied into the inner tube 12 of the nozzle 10 and is ejected downward through four discharge holes 14. The nozzle 10 is made of copper, and cooling water is passed between an outer tube 11 and an inner tube 12, so that the nozzle 10 is water-cooled.

The lower surface 13 of the nozzle 10 has a lower surface 13 along its periphery.
A leak-proof wall 15 is formed that protrudes downward from.

A plate-shaped ceramic guard 16 that covers the lower surface 13 of the area surrounded by the leakage prevention wall 15 is disposed below the lower surface 13. This ceramic guard 16 has a hole 20 formed at a position aligned with the discharge hole 14, and is fixed to the leak prevention wall 15 by a copper bottle 11 while being fitted into the leak prevention wall 15. The ceramic guard 16 is made of a combination of silicon nitride and silicon carbide, for example.
is installed on the lower surface 13 of the nozzle, a seal 1 made of ceramic fiber is installed between the leakage prevention wall 15 and the ceramic guard 16.
8, and then weld copper to the lower end of the inner surface of the S-proof wall to form a built-up portion 19. Next, the ceramic guard 1G is fixed to the leakage prevention wall 15 using the copper bottle 11.

Therefore, the leakage prevention wall 10 serves as a support for fixing the ceramic guard 16, and also serves as a support for fixing the bottle 11 and the built-up portion 1.
9 is a fixing means for fixing the ceramic guard 16 to the lower surface of the nozzle.

In the converter blowing lance configured in this way, as the blowing progresses, molten steel and slag particles scatter toward the lance. In this case, the sea wall 15 prevents the molten steel and slag attached to the upper part of the nozzle 10 and the circumferential surface of the lance body from dripping along the circumferential surface and getting around to the lower surface 13 of the nozzle 10 and the ceramic guard 16. . Furthermore, the sea wall 15 separates the molten metal and slag adhering to the circumferential surface of the nozzle 10 from the molten metal and slag adhering to the ceramic guard 16, and when these solidify, the base metal adhering to the ceramic guard 16 is removed from the lance. This prevents the entire bullion from being supported and makes it easier for the bullion to fall.

The ceramic guard 16 prevents molten steel and slag that are scattered toward the nozzle 10 from below the nozzle 10 through the gap between the jets of oxygen gas from adhering to the nozzle lower surface 13 . This ceramic guard 16 has a high melting point and low thermal conductivity. Therefore, the cooling ability of the water-cooled nozzle 10 is blocked by the ceramic guard 16, and the adhered molten steel and slag are hardly cooled. In addition, the molten steel and slag adhering to the ceramic guard 16 receive radiant heat from the molten steel in the furnace. Therefore, the molten steel and slag adhering to the ceramic guard 16 are prevented from solidifying and becoming metal.

Further, the seal 18 is connected to the sea wall 15 and the ceramic guard 1.
This prevents molten steel and slag from being inserted between the One possible method for fixing the ceramic guard 16 is to use an adhesive, but in cases where the ceramic guard 16 is exposed to extremely high temperatures, such as a lance nozzle, the adhesive cannot withstand this temperature and the difference in thermal expansion causes shearing force. It is not preferable to use adhesive fixation for reasons such as the possibility of this occurring. Therefore, it has to be fixed mechanically, but if this is done, a gap will be created between the ceramic guard 16 and the seawall 15, and there is a risk that molten steel and slag will be inserted into this gap and the ceramic guard 16 will crack. be.

For this reason, a ceramic fiber seal 18 is inserted between the sea wall 15 and the ceramic guard 16 to prevent molten steel or the like from entering this gap. The seal 18 also acts as a buffer member that prevents thermal stress from occurring due to the difference in thermal expansion between the copper seawall 15 and the ceramic guard 16. In addition, the built-up portion 19 allows
Ceramic guard 16 is prevented from falling off from nozzle 10.

When the converter blowing is finished, the lance is raised and the skirt (
(see Figure 2) is raised to tilt the converter and tap the molten steel. Since the lower surface 13 of the lance 10 is protected by the ceramic guard 16, molten steel and slag are prevented from adhering to the lower surface 13 and the wall becomes thinner, thereby extending its life.

[Effects of the Invention] According to the present invention, since the lower surface of the lance nozzle is protected by the ceramic guard, molten steel and slag particles in the furnace are prevented from scattering and adhering to the lower surface of the nozzle. The wall also prevents molten steel and slag from traveling along the sides of the nozzle and getting around to the bottom surface of the nozzle, preventing the bottom surface of the nozzle from becoming thinner due to adhesion of molten steel and slag and turning it into bare metal. Deformation of the discharge hole due to load is also suppressed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a nozzle portion of a converter blowing lance according to an embodiment of the present invention, and FIG. 2 is an overall view of the converter. 10: nozzle, 11; outer tube, 12; inner tube, 13: lower surface,
14: discharge hole, 15: sea wall, 16: ceramic guard, 17: bottle, 18: seal, 19: built-up part. Applicant Representative Patent Attorney Takehiko Suzue 2nd Ward

Claims (2)

[Claims] (1) In a converter blowing lance that is charged into a converter and sprays oxygen gas from its lower end onto the molten steel in the furnace, the lance is inserted along the periphery of the lower end face of the nozzle installed at the lower end of the lance body A hot water barrier projecting downward from a lower end surface, a ceramic guard that covers the lower end surface of the nozzle in an area surrounded by the hot water barrier, and a fixing means for fixing the ceramic guard to the hot water barrier wall. Characteristic converter blowing lance. (2) The lance for converter blowing according to claim 1, characterized in that a ceramic fiber seal is interposed between the hot water barrier and the ceramic guard.