Metallurgical apparatus – Process
Reexamination Certificate
2000-03-30
2002-06-11
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Process
C266SDIG001, C266S143000
Reexamination Certificate
active
06403021
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of constructing or reconstructing a blast furnace body using a ring block technique in which the blast furnace body is divided into a plurality of sections that are movable to and from the blast furnace hearth site.
A lifting transfer apparatus is provided for lifting and transferring the relevant furnace-body ring sections, or blocks.
The present invention is applicable to dismantling the existing blast furnace body, followed by efficiently either reconstructing another blast furnace body on the same hearth foundation, or newly constructing a blast furnace body on the same site.
2. Description of the Related Art
A conventional method of constructing a blast furnace body comprises the steps of (1) dividing a furnace body shell into small blocks, (2) assembling the furnace body shell at a blast-furnace assembly site by welding, (3) bringing a large number of staves, about 400 to 600 pieces, into the furnace one by one, (4) mounting the staves in predetermined positions, and (5) laying bricks in the furnace. Reconstruction of a blast furnace body in this manner has required a working period of 100 to 130 days.
On the other hand, a so-called furnace-body large ring block technique has been employed recently. This comprises the steps of (1) dismantling a furnace body into ring-shaped units (ring blocks) including a shell, staves and refractories all together, (2) disassembling, repairing and assembling the ring blocks at another site, (3) bringing each of the assembled ring blocks to a blast-furnace assembly site, and (4) connecting and assembling the ring blocks. This construction technique enables a blast furnace body to be reconstructed in a shorter period of not longer than 70 days.
Japanese Examined Patent Publication No. Sho 47-1846 discloses such a technique comprising the steps of (1) dividing a blast furnace into furnace-body ring blocks such as a hearth section, a bosh section, a shaft section, and a top-ring section, (2) constructing the divided furnace-body ring blocks on scaffolds each installed around the blast furnace, the scaffolds having a height that is equal to the height at which the corresponding ring block is to be assembled into the blast furnace, and (3) stacking the furnace-body ring blocks on the foundation of the blast furnace, one above another, while moving around the blast furnace horizontally for each step of stacking each ring block. This is done by using a movable scaffold, and then integrating all the ring blocks into an integral structure.
Also, Japanese Examined Patent Publication No. Sho 53-39322 discloses a technique comprising the steps of (1) dividing a blast furnace into several furnace-body ring blocks, and constructing those ring blocks at a site other than the foundation of the blast furnace, (2) assembling the divided furnace-body ring blocks one by one from the top section using a lifting technique which utilizes an associated tower provided on furnace-body support posts for construction of the blast furnace, and (3) fixing the hearth section on the foundation of the blast furnace along with a hearth base.
The conventional ring block techniques described above require working at a high altitude. The work involves assembling each of the ring blocks on a stand at a height up to about 7 meters above the ground surface. Such work at an elevated level not only necessarily pushes up the cost because of the expense of the stand, but requires improvement from the viewpoint of safety. Regardless of the size scales of the blast furnaces, the foundation of any blast furnace body usually requires an upper end height at about 4 to 6 meters. This is because the blast furnace is installed at a high level so that molten iron coming out of the tapping hole of the blast furnace will flow down through a sloped runner. The flowing steel is then introduced into a torpedo car, or a ladle or the like for carrying the molten iron for processing or use.
When dismantling or constructing or reconstructing a blast furnace using the furnace-body ring block technique, furnace-body ring blocks weighing about 1000 to 2000 tons are each moved from or onto the foundation of the furnace body at a level of about 7 meters above the ground surface for a blast furnace having a capacity of about 4000 to 5000 m
3
. Accordingly, horizontal beams each having a height of 1 to 2 meters are required for supporting the weight of the ring block. Further, when dismantling a blast furnace, the furnace-body ring blocks must be transported from a level of about 7 meters to a furnace-body disassembly site at a lower level. Conversely, when constructing a blast furnace, the furnace-body ring blocks, which have been assembled at a furnace-body ground assembly site at a lower level, must be raised up to a level of about 7 meters above the ground surface and then moved onto the supporting foundation of the furnace body.
A furnace-body carriage car having a height of about 1.5 meters and being able to raise and lower an upper surface is employed to transport the furnace-body ring block. Even with a packing beam mounted on the furnace-body carriage car for dispersion of the ring block weight, however, the total height is only about 3 meters and there still remains a level difference of 4 meters relative to the foundation of the furnace body. A load level-adjusting framework is required to absorb such a level difference. It is necessary to prepare the load level-adjusting framework in number corresponding to the numbers of divided ring blocks to be dismantled and the number of furnace-body ring blocks newly fabricated. Further, since the furnace-body ring blocks are moved on the load level-adjusting framework, the adjusting framework is required to have rigidity enough to endure the weight of each furnace-body ring block throughout its entire length. Thus, the furnace-body ring block technique is a method enabling a blast furnace to be reconstructed in a shorter period, but faces a difficulty in practical use because of the high production cost of the load level-adjusting framework.
To overcome the above-described problem, Japanese Unexamined Patent Publication No. Hei 10-102778 discloses a stationary lifting transfer apparatus for lifting and lowering a furnace-body ring block is installed in an appropriate place outside a blast furnace. When dismantling furnace-body ring blocks, each furnace-body ring block is moved onto a furnace-body carriage car and then transported to a stationary lifting transfer apparatus. A load level-adjusting framework in match with a level higher than the foundation of a blast furnace body is set on the furnace-body carriage car. Thereafter, the furnace-body ring block is lifted by the stationary lifting transfer apparatus, and the load level-adjusting framework is removed from the furnace-body carriage car. Subsequently, the furnace-body ring block is lowered and placed directly on the furnace-body carriage car. The furnace-body ring block is then transported onto a rest stand for storage. On the other hand, a newly fabricated furnace-body ring block is assembled at a ground assembly site at a low level, loaded on the furnace-body carriage car and then transported to the stationary lifting transfer apparatus. After that, the furnace-body ring block is lifted by the stationary lifting transfer apparatus to a level allowing the furnace-body ring block to be moved onto the foundation of the blast furnace body. Subsequently, the furnace-body ring block is loaded on the furnace-body carriage car on which the load level-adjusting framework is positioned, and then transported to the foundation of the blast furnace body.
DETAILED DESCRIPTION OF THE PRIOR ART
The method of constructing a blast furnace body disclosed in the above-cited Japanese Unexamined Patent Publication No. Hei 10-102778 will be described below in more detail. In the disclosed method, a furnace-body carriage car having a structure as shown in
FIGS. 1A and 1B
of this application is employed.
FIG. 1A
is a s
Fujita Masao
Kojima Hirotaka
Kastler Scott
Kawasaki Steel Corporation
Schnader Harrison Segal & Lewis LLP
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