JPS6316443B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is a method for protecting a blast furnace mouth shell, and more specifically, the area where a refractory brick has fallen off at the blast furnace mouth part is replaced with a cast metal panel whose inside of the furnace is covered with a refractory material. This article relates to a method of protecting the furnace mouth shell by covering it with (Conventional technology) Blast furnace refractory bricks are constantly exposed to temperature fluctuations, high-temperature corrosive gases, impact from charging materials, abrasion, etc., and are therefore prone to spalling, collapsing, and falling off, which can shorten the life of the blast furnace. Overcoming this has become a major problem because Conventionally, the furnace mouth refractory bricks have been repaired mainly by hot spraying monolithic refractories, but because the adhesive strength with the remaining firebricks is low, the sprayed materials fall off early and the furnace mouth remains damaged for a long period of time. It was impossible to prevent damage to the bricks. In particular, if the air is left out for a long period of time, the refractory bricks at the mouth of the furnace may fall off due to large disturbances such as temperature fluctuations and localized heating due to uneven flow of reducing gas in the furnace circumferential direction. In such a state, the heat load on the shell at the mouth of the furnace increases, and cracks occur in the shell due to the occurrence of hot spots, etc., resulting in a situation such as blow-down of the blast furnace. Conventionally, a method for repairing the condition in which some of the blast furnace refractory bricks have fallen off and there are remaining bricks has been proposed as a blast furnace wall repair method (Special Publication No. 58-50288), but most of the refractory bricks at the furnace mouth are There is no way to repair it once it has fallen off. The method disclosed in Japanese Patent Publication No. 58-50288 is to tighten and fix molded refractory panels reinforced with refractories or wire mesh, etc. by using vibration forming method, etc. to the steel shell through the steel shell openings using chains, and then to prevent further damage. The gap formed by the furnace wall bricks and panels is filled with refractory filling holes that have penetrated the steel shell and the furnace wall in advance.
By press-filling monolithic refractories from outside the furnace and solidifying them to form the furnace wall, damaged parts of the furnace wall are strongly protected by the filled refractories and panels that have excellent heat, impact, and corrosion resistance. The aim is to achieve a significant extension of reactor life. (Problem to be solved by the invention) However, in Japanese Patent Publication No. 58-50288, a method of fixing the formed refractory panel to the steel shell with chains is used, but it is impossible to hold the panel vertically with chains. Since the panel must be supported by a support tube that protrudes into the furnace, there is a risk that the panel may slide downward. Furthermore, the panel itself does not have a structure in which monolithic refractories are cast into a solid metal frame, etc., so the lifespan of the refractories is short, and if the panel breaks, the monolithic refractories press-fitted between the steel shell and the panel will be damaged. It is exposed in the furnace and has the problem of falling off early, similar to the conventional method of spraying refractories. In addition, if most of the refractory bricks at the furnace mouth have fallen off, the furnace wall can be rebuilt by simply spraying refractories, by vibrating molding, etc., or by using panels made of refractories embedded with wire mesh, etc. Since these methods of protection were not expected to be sufficiently effective, it was necessary to resort to temporary methods of applying glue, such as cooling the steel shell by sprinkling water from outside. (Means for Solving the Problems) An object of the present invention is to provide a blast furnace mouth shell protection method that can eliminate and improve the drawbacks and problems of conventional methods. The above object can be achieved by providing a method for protecting a blast furnace mouth shell as described in the claims. That is, the present invention provides a method for protecting the shell at the mouth of a blast furnace. A cast panel with fixing bolts on the sides is taken into the furnace through the furnace top opening and faces the shell protection part; through the furnace body opening, the panel is pulled toward the shell side and the fixed to the steel shell with bolts; constructing a furnace wall by press-fitting a refractory with good thermal conductivity into the gap between the steel shell and the panel;
Furthermore, the present invention relates to a blast furnace mouth shell protection method that cools the panel through the shell by sprinkling water on the outer surface of the shell during operation. The method for protecting the blast furnace mouth shell of the present invention will be described in detail below. The present invention protects the furnace mouth shell by attaching a cast block (hereinafter referred to as a caster panel) in which a monolithic refractory is cast in advance to the area where the blast furnace mouth refractory bricks have fallen off. FIG. 1 is a side cross-sectional view of the upper part of the blast furnace, in which the raw material 1 in the furnace is lowered below the fallen refractory brick part a, and the blast furnace is reduced in size and is in a resting state. The left half of the figure shows the state before the invention,
The right half of the figure shows an outline of the caster panel installation. In the figure, 2 is a refractory brick, 3 is a stave cooler, 4 is an iron shell, 5 is an ore support, 6 is a movable armor, 7 is a large bell, 8 is a movable armor plate replacement port, and 13 is a hoist. is an existing structure. The structure of the repair caster panel 9 is as shown in the vertical cross-sectional view of the installation shown in FIG. It is held firmly in place by support anchors embedded in the block.
The material for the monolithic refractory should be selected with excellent heat resistance, impact resistance, abrasion resistance, CO gas resistance, and alkali resistance, taking into consideration the furnace temperature and gas properties. The surface of the casting block 14 that comes into contact with the steel shell 4 has an appropriate curvature to fit the inner surface of the steel shell, as shown in FIG. 3, which is a view taken along arrow A-A in FIG. At the same time, after the casting block 14 is installed in the furnace, compressible sealing material 17 is applied in advance on three sides except for the top surface in order to seal the press-fitting material 16 that is filled into the gap between the iron skin 4 and the casting block 14. It is attached with adhesive, etc. Further, a fishing gear 14a for taking the casting block 14 into the furnace is cast and protrudes from the inner surface of the furnace. The size of the caster panel 9 is determined by the falling range of the refractory bricks, the size of the movable armor plate replacement port 8, etc., but as an example, the width is approximately 1 mm.
Dozens of pieces measuring 1.7m long and 0.25m thick will be prepared. Furthermore, a plurality of fixing bolts 18 are embedded in the caster panel 9, and at least two of them are fixed to the eye nut 1 as shown in FIG.
9 is screwed in, and a wire 10 is attached to this so that the caster panel 9 can be drawn toward the steel shell 4 side. As shown in FIG. 1, the blast furnace shell 4 is provided with openings (section b in FIG. 1) for attaching caster panel fixing bolts 18 after the fallen refractory bricks. As shown in FIGS. 2 and 3, the shell 4 side of the caster panel 9 has a concave shape, and the press-fit material 16 is inserted through the press-fit tube seat 21 provided in the shell opening near the lower end. It is about to be filled. The cast block 14 of the caster panel 9 does not deform or crack due to temperature changes in the furnace, and maintains itself in a healthy condition.
It is necessary to reduce thermal expansion to prevent cracking and falling off of the monolithic refractory 15 on the surface. Therefore iron skin 4
Since water is sprinkled from outside to cool the casting block 14 through the press-fit material 16, the press-fit material 16
Select one with high thermal conductivity. However, if a material with an unnecessarily high thermal conductivity is used, the cost will increase, so the inside of the cast block 14 when the thermal conductivity of the press-fit material 16 is varied according to the temperature and physical property values shown in Table 1. The temperature of the outer surface was estimated.

【table】

[Table] The results are shown in Figure 6.As is clear from the figure, even if the thermal conductivity is set to 4Kcal/hm℃ or higher, the temperature of the cast block decreases only slightly; The temperature of the inner and outer surfaces of the material is about 120°C, which is within a range that can be used as a structure. Therefore, the thermal conductivity of press-fit material 16 is 4Kcal/
It turned out that about hm℃ is sufficient. As the press-fitting material 16, a graphite-based material which has excellent press-fitting properties was selected. Next, the repair operation of the blast furnace mouth will be explained. When the preparation of the caster panel 9 to be installed in the furnace is completed, the charge 1 is reduced in size to the mounting part of the caster panel 9 as shown in FIG. 1, and the furnace is put into a rest period. Next, the wire ropes 12 and 11 are hung around the hanging tools 14a and bolts 18 of the caster panel 9, and suspended by the hoist 13.
hang down near the installation part inside the furnace. The wire rope 10 attached to the back surface of the caster panel 9 is pulled through the opening b. Next, as shown in FIG. 5, after connecting the connecting bolt 19 to the caster panel fixing bolt 18, the caster panel 9 is fixed to the steel shell 4 by tightening the nut 20. For the parts where the wire rope 10 is attached, after removing the eye nuts 19, fix them to the steel shell 4 in the same manner. The two bolts 18 and 19 were connected to fix the caster panel 9.
This is because the width of the armor plate replacement port 8 is small, and if it can be hung into the furnace from a large furnace top opening, it can be fixed with a single bolt. The bolt part is covered with a cap 20a and welded to seal it with gas.
Next, a press-fitting material 16 made of graphite monolithic refractory is filled between the iron skin 4 and the cast block 14 from the press-fit tube seat 21. This press-fitting material 16 is sealed by the compressible sealing material 17 stretched on the three sides of the caster panel 9, so it will overflow from the top surface where the sealant is not stretched, so check this and press-fit. Completed. Finally, unshaped refractory bricks are filled in by spraying repair between the joints of the caster panel 9 and between the caster panel 9, the ore support 5, and the remaining refractory bricks 2, and the furnace mouth profile is adjusted. (Example) A second example of the method for protecting the furnace mouth shell according to the present invention is described below.
As shown in Fig. 3. The space between the cast iron block 14 and the iron skin 4 is filled with a graphite press-in material 16 with a moisture content of approximately 26%. The thermal conductivity of this press-fit material 16 after drying is approximately 4.01 Kcal/mh°C. During operation after repair, water was sprinkled on the steel shell 4 from the outside. A thermocouple was inserted into the iron shell 4 side of the cast iron block 14 to measure the temperature, and the temperature was about 130°C, which was as expected. (Effects of the present invention) In the furnace shell protection method of the present invention, by attaching the caster panel to the furnace mouth iron plate, the thermal load on the steel shell is reduced and thermal deformation and cracking can be prevented. Lifespan has been significantly extended. In addition, the caster panel's monolithic refractory material is cast into a solid cast block, and this is cooled by water spraying on the steel shell through press-fitting material, so it can be used for a long time without cracking or falling off. Ta. Furthermore, since the caster panel is a factory-made product, its thickness is all the same, and by installing it, the profile in the circumferential direction of the furnace mouth is adjusted, the load is improved, and productivity can be improved by reducing the coke ratio. , the effect is remarkable. Furthermore, the method of the present invention can be applied not only to repairs but also to newly constructed blast furnaces, and in this case, the construction cost can be significantly reduced compared to the method in which the conventional stave cooler is installed up to the ore receiver. Can be done.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of the furnace mouth (left half: before repair, right half panel installation procedure), Figure 2 is a caster panel installation diagram, Figure 3 is a view taken along arrow A-A in Figure 2, Fourth
The figure shows the eyepiece installation diagram for retracting the caster panel.
FIG. 5 is a longitudinal sectional view of the caster panel fixing part, and FIG. 6 is a diagram showing the relationship between the thermal conductivity of the press-fit material and the temperature of the cast iron block. 1... Furnace raw material, 2... Firebrick, 3... Stave cooler, 4... Iron shell, 5... Ore support,
6...Movable armor, 7...Big bell, 8...
Movable armor plate replacement port, 9... Caster panel, 10... Wire rope, 11...
Wire rope, 12...Wire rope, 13
...Hoist, 14...Casting block, 15...
Monolithic refractory, 16... Press-fitting material, 17... Contractible sealing material, 18... Bolt, 19... Bolt, 2
0... Nut, 20a... Cap, 21... Press-fit tube seat, 22... Spraying material.

Claims (1)

[Claims] 1. To protect the blast furnace mouth shell: Reduce the blast furnace charge to below the furnace wall repair area,
After the wind has stopped, the inside surface of the furnace is covered with refractory material, fixing bolts are protruded from the other side of the steel shell, and retractable sealing material is glued to three sides except the top surface. The cast panel is taken into the furnace through the furnace top opening,
face the steel shell protection part; draw the panel to the shell side through the furnace body opening and bring it into close contact with the shell; and fix it to the shell with the bolts; The furnace wall is constructed by press-fitting graphite refractories into the gap between the panels and the retractable sealing material; A blast furnace mouth shell protection method characterized by cooling a panel.