JP7267668B2 - Furnace bottom cooling method in blast furnace refurbishment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hearth bottom cooling method in blast furnace refurbishment, and, for example, to a method for cooling residual pig iron in a blast furnace prior to dismantling of the residual pig iron.

In blast furnaces in steelworks, the refractory lining and furnace body cooling equipment deteriorate or break during long-term operation. (Blast furnace renovation) is being carried out.

This blast furnace refurbishment is described, for example, in Patent Literature 1, which discloses a method of dismantling the furnace after cooling the inside of the furnace by injecting water into the furnace when refurbishing the blast furnace. Further, for example, Patent Literature 2 discloses that an opening is provided on one surface of a steel shell to blast and dismantle the residual iron inside. Further, for example, Patent Literature 3 discloses providing a through-hole for passing a wire saw through a base portion under the bottom of a blast furnace when refurbishing a blast furnace. Further, for example, in Patent Document 4, between the hearth and the base of the blast furnace, a gap or a cooling pipe is installed as a heat transfer shielding means for shielding heat transfer from the hearth to the base during operation of the blast furnace. A configuration is disclosed.

JP-A-52-23508 Japanese Patent Publication No. 08-26373 JP-A-2002-339007 JP 2009-120945 A

By the way, modern steelworks are constructed so that the main lines such as blast furnaces, steelmaking, rolling, surface treatment, etc., and the many infrastructures surrounding the main lines are consistently optimized. The balance of energy and distribution is designed on the premise that each line will produce a certain amount. For this reason, although it is planned to be carried out once every ten years or so, each steelworks has only one to three blast furnaces, and the fact that the most upstream blast furnace is out of service for a long period of time is a major disadvantage. Therefore, in steelworks, it is important to shorten the construction period for blast furnace refurbishment.

Therefore, cooling of the residual pig metal ingots in the furnace is essential for early and safe scrapping of the residual pig metal in the blast furnace refurbishment. has not been sufficiently considered, and there is a problem that it takes time to cool the residual iron lump. That is, as described in Patent Document 1, water is generally injected from the upper part of the blast furnace to cool the residual iron lump, but it takes time to cool the inside of the residual iron lump. In addition, a large amount of water vapor may be generated in the furnace, resulting in long hours of blindness. In particular, when the casting floor and the furnace bottom have only one opening, there are few parts of the residual iron ingot that come into contact with the outside air, making natural cooling difficult. In addition, even if the surface temperature of the residual iron lump is lowered, the internal temperature may be high. In some cases, the work becomes stagnant, such as the confirmation work taking time. In addition, the cooling pipe provided as equipment of the blast furnace described in Patent Document 4 is intended to shield heat from being transmitted from the furnace bottom to the base as described above, and is located under the refractory bricks at the furnace bottom. Since it is provided on the side, it is not suitable for rapidly cooling the residual pig iron lump.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described technical background, and an object of the present invention is to shorten the time required for cooling the residual iron ingot during refurbishment of a blast furnace.

In order to solve the above-mentioned problems, the bottom cooling method for blast furnace refurbishment according to claim 1 of the present invention includes: a step of drilling a plurality of bottomed holes from the drilling start position toward the outer peripheral side surface on the opposite side; inserting a cooling pipe into each of the plurality of bottomed holes; a step of injecting cooling water into each of the plurality of bottomed holes through the cooling pipes to cool the residual iron ingot in the blast furnace.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the bottomed hole is bored in the residual pig iron lump.

The invention according to claim 3 is characterized in that, in the invention according to claim 1, the bottomed hole is bored in the refractory layer.

The invention according to claim 4 is the invention according to claim 3, wherein the plurality of bottomed holes are arranged along the bottom portion of the residual iron lump when viewed from the front of the outer peripheral side surface of the furnace bottom portion. It is characterized by

The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein a step of determining an opening range in a part of the iron shell provided on the outer peripheral side surface of the bottom part of the blast furnace. and removing the steel shell within the opening range before drilling the bottomed hole.

The invention according to claim 6 is the invention according to any one of claims 1 to 4, wherein the bottomed hole is drilled through an iron shell provided on the outer peripheral side surface of the bottom of the blast furnace. characterized by

The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the plurality of bottomed holes are radially extending in a drilling direction of the bottomed holes in plan view. It is characterized in that it is arranged in

The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the plurality of bottomed holes are inclined in a cross-sectional view so as to descend in the drilling direction of the bottomed holes. characterized by being formed in

The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the diameter of the cooling pipe is smaller than the diameter of the bottomed hole, and the tip surface of the cooling pipe is closed. A plurality of injection holes for injecting the cooling water injected into the cooling pipe to the outside are formed on the outer peripheral side surface of the cooling pipe along the extending direction of the cooling pipe. The pipe is characterized in that the plurality of injection ports are inserted into the bottomed hole so as to face the residual iron lump.

According to the first aspect of the invention, it is possible to cool the residual pig metal in the furnace through the plurality of bottomed holes.

According to the second aspect of the invention, it is possible to improve the cooling efficiency of the residual iron lump.

According to the third aspect of the invention, it is possible to reduce the time required to drill a plurality of bottomed holes. In addition, by not spraying water directly on the residual iron mass, generation of steam in the furnace can be suppressed. Therefore, it is possible to shorten the cooling operation time of the residual iron lump.

According to the fourth aspect of the invention, since the distance between each bottomed hole and the residual iron lump becomes short, the cooling efficiency of the residual iron lump is improved when cooling water is flowed through the plurality of bottomed holes. becomes possible.

According to the fifth aspect of the invention, when the bottomed hole is drilled, the bottomed hole can be easily drilled because there is no steel shell at the drilling position of the bottomed hole.

According to the sixth aspect of the invention, work can be carried out without forming an opening in the shell on the side of the hearth bottom of the blast furnace before cooling, so that work safety can be improved.

According to the seventh aspect of the invention, since the plurality of bottomed holes can be arranged so as to overlap in a plan view over a wide range of the bottom surface of the ingot, the cooling water is flowed through the plurality of bottomed holes. Sometimes, it becomes possible to improve the cooling efficiency of the residual iron lump. Further, when openings are provided in the outer shell of the blast furnace, the range of the openings can be reduced, which is advantageous in terms of reuse of the blast furnace.

According to the eighth aspect of the invention, when the cooling water is allowed to flow through the plurality of bottomed holes, the cooling water accumulates in each of the bottomed holes. be possible.

According to the ninth aspect of the invention, since the cooling pipes can circulate the cooling water well in the bottomed holes, the residual pig metal lumps in the furnace can be cooled from the lower side, and the residual pig metal lumps can be cooled. It becomes possible to improve the cooling efficiency.

1 is a schematic longitudinal sectional view of an example of a blast furnace to which a hearth bottom cooling method in blast furnace refurbishment according to one embodiment of the present invention is applied; FIG. 4 is an enlarged vertical cross-sectional view of the hearth mantel in the process of forming an opening in the shell of the blast furnace; 3 is an enlarged vertical cross-sectional view of the hearth mantel in the refractory drilling step after the step of FIG. 2; FIG. FIG. 4 is an enlarged vertical cross-sectional view of the hearth mantel after the refractory drilling process; FIG. 5 is a longitudinal sectional view taken along the line II of FIG. 4; FIG. 5 is a plan view of a hearth mantel schematically showing the planar arrangement of cooling holes in FIG. 4 ; FIG. 7 is an enlarged vertical cross-sectional view of the furnace bottom mantel in the step of inserting cooling pipes after the steps of FIGS. 3 to 6; (a) is an enlarged vertical cross-sectional view of the main part of the hearth mantel of FIG. 7, and (b) is an enlarged perspective view of the main part of the cooling pipe inserted into the hole for cooling the residual iron lump. 8(a) is an enlarged vertical cross-sectional view of the main part of the hearth mantel of FIG. 8(a), and FIG. 9(b) is a vertical cross-sectional view taken along the line II--II of FIG. 9(a). (a) is an enlarged vertical cross-sectional view of the main part of the furnace bottom mantel in the residual iron lump cooling process after the processes of FIGS. 7 to 9, and (b) is an enlarged perspective view of the essential part of the cooling pipe in the residual iron lump cooling process. . 10(a) is an enlarged vertical cross-sectional view of the main part of the hearth mantel shown in FIG. 10(a), and FIG. 11(b) is a vertical cross-sectional view taken along line III--III of FIG. 11(a). (a) is a perspective view of the main part of a modified example of the cooling pipe, (b) is an enlarged vertical cross-sectional view of the main part of the hearth mantel when the cooling pipe of FIG. b) is a vertical cross-sectional view taken along line IV-IV.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment as an example of the present invention will be described in detail below with reference to the drawings. In the drawings for describing the embodiments, in principle, the same components are denoted by the same reference numerals, and repeated description thereof will be omitted.

FIG. 1 is a schematic vertical cross-sectional view of an example of a blast furnace to which a bottom cooling method in blast furnace refurbishment according to the present embodiment is applied.

A blast furnace 1 has a base 2 , a base beam 3 provided on the base 2 , and a furnace body 4 provided on the base beam 3 . A furnace body turret (not shown) is provided around the blast furnace 1, and the entire blast furnace 1 is supported by the furnace body turret. Although not particularly limited, the height of the blast furnace 1 is, for example, about 43 m, and the diameter is, for example, about 17 m.

The base portion 2 is made of concrete, for example. The bottom beam 3 on the base portion 2 consists of a plurality of H-section steels (not shown) arranged side by side in the upper surface of the base portion 2 and cooling pipes (fig. not shown). The bottom beam 3 has a heat transfer function to cool the upper side of the bottom beam 3 by cooling water flowing through the cooling pipe, and a heat insulation function to prevent the heat of the furnace body 4 from being transferred to the base portion 2. there is Note that the bottom beam 3 is joined to the bottom of the furnace body 4 .

The furnace body 4 is a vertical cylindrical structure, and has a furnace bottom mantel (furnace bottom portion) 4A and an upper mantel 4B in order from the bottom. The upper mantel 4B is, in order from the bottom, an upward spread morning glory part 4B1, a straight body furnace belly 4B2, a downward spread furnace chest part 4B3, a straight body furnace mouth part 4B4, and a furnace top part 4B5 that closes the furnace mouth. have. The furnace top 4B5 is provided with, for example, a supply unit MP for supplying iron ore, coke, and limestone into the furnace, and an exhaust pipe EP for exhausting gases in the furnace.

The outer peripheral side surface of such a furnace body 4 is covered with a steel shell 5, for example. The inner periphery of the steel shell 5 is lined with a refractory 6A such as chamotte bricks or silicon carbide bricks. Furthermore, a plurality of water-cooled metal fittings (not shown) for cooling called staves are embedded between the steel shell 5 and the refractory material 6A.

A refractory (refractory layer) 6B such as carbon bricks is provided on the floor beam 3 at the bottom of the furnace body 4 (inside the furnace bottom mantel 4A). Residual iron ingots Ri are deposited on the refractory 6B at the bottom of the furnace. The residual pig-metal lump Ri here includes a layer of lumps composed of pig iron solidified by cooling the molten pig-iron remaining in the furnace, mixed pig-iron mixed with pig iron and coke, etc., and impurities formed thereon. A layer of pig iron lumps is also shown. Also, a soft content C such as coke is deposited on the residual iron mass Ri. The cross-sectional shape of the furnace bottom is, for example, bowl-shaped (concave in cross section). For this reason, the bottom portion of the residual iron ingot Ri is also formed in a downwardly convex, substantially circular arc shape.

Next, an example of a refurbishment method for the blast furnace 1 shown in FIG. 1 will be described with reference to FIGS. 2 to 11. FIG. FIG. 2 is an enlarged vertical cross-sectional view of the hearth mantel in the process of forming an opening in the shell of the blast furnace.

First, as shown in FIG. 2, after determining the opening range in a part of the steel shell 5 provided on the side surface of the hearth mantel 4A, the steel shell 5 in the opening range is removed to form the opening AP. . The refractory 6B is exposed from the opening AP provided in the opening range. In addition, since the steel shell 5 has a complicated structure such as the above-mentioned water-cooled hardware (stave) being joined, it is desired to be reused as much as possible, so the opening range (opening AP) is possible preferably as small as possible.

Next, FIG. 3 is an enlarged longitudinal sectional view of the hearth mantel in the refractory drilling process after the process of FIG. In this step, a plurality of holes for cooling the residual iron lump are drilled in the refractory 6B through the opening AP of the opening range by the drilling machine DM. That is, a plurality of holes are drilled from the drilling start position toward the outer peripheral side surface on the opposite (true back) side. 4 is an enlarged vertical cross-sectional view of the hearth mantel after the refractory drilling process, FIG. 5 is a vertical cross-sectional view taken along the line II in FIG. 4, and FIG. 6 schematically shows the planar arrangement of the cooling holes in FIG. 1 is a plan view of a hearth mantel with a bottom; FIG. In addition, in FIG. 6, the steel shell 5 is hatched in order to make the drawing easier to see.

As shown in FIGS. 4 and 6, the plurality of holes CH drilled in the refractory 6B are bottomed holes. That is, the hole CH passes from the opening AP under the iron ingot Ri and extends linearly toward the outer peripheral side on the opposite side (true back) of the opening AP. It terminates at a position of refractory 6B that does not reach skin 5. Although not particularly limited, the diameter of the hole CH is, for example, approximately 65 to 100 mm.

By making the hole CH a bottomed hole without penetrating to the outer peripheral side surface on the opposite side, it is possible to reduce the work of removing a part of the outer periphery of the steel shell 5 on the opposite side to form an opening. Labor for opening can be reduced, and work time for opening the steel shell 5 can be shortened. In addition, since only one opening is required for the shell 5, it is advantageous in reusing the blast furnace 1.

In addition, by drilling the holes CH in the refractory 6B instead of drilling the residual iron ingot Ri itself, compared to the case of drilling the holes CH in the residual iron ingot Ri, the work of drilling the holes CH can be reduced, and , the time for drilling the holes CH can be shortened. Moreover, since there is no shell 5 at the drilling position of the hole CH, the hole CH can be drilled easily.

Further, as shown in FIG. 4, the plurality of holes CH are formed obliquely so as to descend from the opening AP toward the tip in a cross-sectional view. As will be described later, when cooling water is allowed to flow through the plurality of holes CH, the cooling water is accumulated in each of the holes CH, thereby improving the cooling efficiency of the residual iron mass Ri.

Further, as shown in FIG. 5, the plurality of holes CH are arranged along the bottom of the residual iron lump Ri when the opening AP is viewed from the front. That is, the plurality of holes CH are arranged so as to surround the bottom of the residual pig metal lump Ri, and are formed at positions as close to the residual pig metal lump Ri as possible. As a result, the distance between each hole CH and the residual iron lump Ri can be shortened, so that the efficiency of cooling the residual iron lump Ri can be improved when cooling water is flowed through the plurality of holes CH, as will be described later. can be done. When the blast furnace 1 is refurbished, the shape of the furnace bottom and the position of the residual iron ingot Ri may differ from those at the time of design due to damage to the refractory 6B under the residual iron ingot Ri. Since a plurality of thermometers are installed in the plane direction and the height direction in order to manage the temperature state during operation of the blast furnace 1, the shape of the furnace bottom and the position of the residual iron ingot Ri can be determined from the measurement results. can be estimated. Therefore, the holes CH can be formed along the bottom of the residual iron lump Ri as described above.

Further, as shown in FIG. 6, the plurality of holes CH are arranged radially so as to spread from the opening AP toward the side surface on the opposite side in a plan view. As a result, the plurality of holes CH can be arranged so as to overlap in plan view over a wide range of the bottom surface of the residual iron lump Ri even from the small opening AP. Therefore, as will be described later, when cooling water is allowed to flow through the plurality of holes CH, the cooling efficiency of the residual iron lumps Ri can be improved. In addition, since the opening AP can be made smaller, the labor for opening can be reduced, and the work time for opening can be shortened. Moreover, since the opening AP can be made small, it is advantageous in reusing the blast furnace 1 .

Next, FIG. 7 is an enlarged vertical cross-sectional view of the hearth mantel in the cooling pipe insertion process after the processes of FIGS. 3 to 6, FIG. (b) is an enlarged perspective view of a main part of a cooling pipe inserted into a hole for cooling the residual iron lump; FIG. b) is a longitudinal sectional view taken along the line II-II in FIG. 9(a).

Here, as shown in FIG. 7, a cooling pipe CP is inserted into each of the plurality of holes CH. The cooling pipe CP, as shown in FIGS. 8 and 9, is a cylindrical tubular pipe for flowing cooling water. As shown in FIGS. 8(b) and 9, the cooling pipe CP has a plurality of injection holes Hi on the outer peripheral side surface of the cooling pipe CP for injecting the cooling water injected into the cooling pipe CP to the outside. Perforations are made at predetermined intervals along the existing direction. The diameter of the cooling pipe CP is smaller than the diameter of the hole CH, and is not particularly limited, but is, for example, about 50A.

As shown in FIG. 9, the cooling pipe CP is arranged between the outer circumference of the cooling pipe CP and the inner circumference of the hole CH (mainly above the cooling pipe CP) with the plurality of injection holes Hi directed toward the residual iron lump Ri. side) is inserted into the hole CH so as to form a gap. In this example, as shown in FIGS. 8(b) and 9(a), the tip of the cooling pipe CP is closed.

Next, FIG. 10(a) is an enlarged vertical cross-sectional view of the main part of the furnace bottom mantel in the residual iron lump cooling process after the processes of FIGS. 7 to 9, and FIG. FIG. 11(a) is an enlarged vertical cross-sectional view of the main part of the hearth mantel of FIG. 10(a), and FIG. 11(b) is a vertical cross-sectional view taken along line III-III of FIG. 11(a). . 10 and 11 indicate the direction in which the cooling water flows.

Here, as shown in FIGS. 10 and 11, cooling water W (see FIG. 11) under pressure is injected into each cooling pipe CP inserted into each hole CH, and each cooling pipe CP The cooling water W is injected from the injection port Hi toward the residual iron lump Ri side. At this time, the cooling water W can be well circulated in the holes CH by arranging the cooling pipes CP in the holes CH, so that the residual iron ingots Ri can be efficiently cooled from the lower side. Moreover, since the cooling water W is not directly sprinkled onto the residual iron lump Ri, it is possible to suppress the generation of water vapor in the furnace.

Here, at the same time as cooling the residual iron ingot Ri from the lower side as described above, cooling water is also injected into the furnace from above the blast furnace 1 (see FIG. 1), thereby cooling the residual iron ingot Ri from the upper portion. may also be cooled. As a result, the cooling efficiency of the residual iron ingot Ri can be further improved, so that the time required for cooling the residual iron ingot Ri can be further shortened. In this case, since the residual iron ingot Ri is also cooled from below, the generation of water vapor in the furnace can be suppressed. The start time of water injection from above the residual iron lump Ri may be delayed from the start time of cooling the lower portion of the residual iron lump Ri. That is, the residual pig metal lump Ri may be cooled from below to lower the temperature of the residual pig metal lump Ri to some extent, and then cooling water may be injected from above the residual pig metal lump Ri. Thereby, generation of water vapor in the furnace can be suppressed.

Next, after removing the contents C on the residual iron mass Ri of the hearth mantel 4A shown in FIG. And the residual iron lump Ri is dismantled by a heavy machine such as a piercing machine and carried out of the furnace. At this time, in this embodiment, since the internal temperature of the residual iron lump Ri is lowered by the above-described cooling process, a large amount of water is supplied from the tip of the bit during drilling for dismantling the residual iron lump Ri. of water vapor is not generated. As a result, the work does not stagnate due to steam during dismantling of the residual pig iron lump Ri, so that the residual pig metal lump Ri can be dismantled safely and in a short period of time. Therefore, the construction period for blast furnace refurbishment can be shortened.

Next, for example, the old blast furnace is carried out by the carry-out block construction method, and the new blast furnace is brought into the site of the old blast furnace to complete the renovation of the blast furnace. In other words, after dividing the old blast furnace into multiple blocks and removing each block in order from the bottom, multiple blocks for the new blast furnace made on a separate site in parallel with the operation of the old blast furnace were brought in from the top. , Each block of the new blast furnace is piled up, and the parts where each block touches are joined with steel shells, pipes, etc. to complete the new blast furnace.

Although the invention made by the present inventor has been specifically described based on the embodiments, the embodiments disclosed in this specification are illustrative in all respects and are limited to the disclosed technology. isn't it. That is, the technical scope of the present invention should not be construed in a restrictive manner based on the description of the above embodiments, but should be construed according to the description of the scope of claims. All modifications are included as long as they do not deviate from the description technology and equivalent technology and the gist of the claims.

For example, the configuration of the cooling pipe CP is not limited to that shown in FIGS. 8(b) and 9, and various modifications are possible. For example, FIG. 12(a) is a perspective view of essential parts of a modification of the cooling pipe, and FIG. 12(c) is a longitudinal sectional view taken along line IV-IV of FIG. 12(b). The arrows in FIGS. 12(a) and 12(b) indicate the direction in which the cooling water flows.

In this case, no injection port is formed on the outer circumference of the cooling pipe CP. and injected into the hole CH from the tip surface of the cooling pipe CP, and in the process of returning from the bottom of the hole CH to the inlet of the hole CH through the hole CH, the residual pig iron in the furnace is cooled from its lower side. It's like Otherwise, it is the same as described above.

Further, in the above example, the case of drilling the hole CH after removing the shell 5 in the opening range of the side surface of the hearth bottom of the blast furnace 1 to form the opening AP has been described, but the present invention is not limited to this. , the hole CH may be drilled while leaving the steel shell 5 in the opening range of the side surface of the hearth bottom of the blast furnace 1 . In this case, the work can be carried out without forming the opening AP in the shell 5 on the side surface of the hearth bottom of the blast furnace 1 before cooling, so that the safety of the work can be improved.

Further, in the above example, the case of drilling the holes CH in the refractory 6B has been described, but the present invention is not limited to this. Holes CH may be drilled in both the mass Ri and the refractory material 6B. When drilling the hole CH in the residual pig metal lump Ri, it may penetrate through the residual pig metal lump Ri, or may terminate at a position in the middle of the residual pig metal lump Ri. In any case, when the holes CH are drilled in the ingot Ri, the ingot Ri can be directly cooled, so that the cooling efficiency of the ingot Ri is improved more than in the case of drilling the holes CH only in the refractory 6B. be able to. As for the method of drilling the hole CH, if the hole CH hits the residual iron lump Ri in the middle of drilling, the hole CH may be pierced through the residual iron lump Ri, or the hole may be terminated in the middle of the residual iron lump Ri. However, the hole may be re-drilled while avoiding the residual iron mass Ri. Further, it is considered that the cooling effect is better if the residual iron Ri is pierced and water is directly injected as described above, but piercing the residual iron Ri takes more time than drilling the refractory 6B. Therefore, both the case of drilling the residual iron Ri and the case of drilling the refractory 6B are conceivable. Which of the method of cooling the residual pig iron Ri directly and the method of cooling it through the refractory 6B should be selected depends on the cooling effect and the time required for drilling.

Further, the method of dismantling the residual pig iron after cooling the residual pig iron is not limited to the above-described method, and various modifications are possible. , a method of dismantling the residual pig iron by carrying it out from the opening AP can also be applied. In this case, since the damage to the blast furnace 1 can be reduced, it is effective when the blast furnace 1 is reused. Alternatively, the residual iron ingots Ri in the furnace can be dismantled by a blasting method through an opening AP formed on the side surface of the bottom of the blast furnace 1 .

In the above description, the case where the hearth cooling method for blast furnace refurbishment of the present invention is applied to the blast furnace refurbishment method using the block construction method is shown. Blast furnace refurbishment methods using the strip method for dismantling and installation, the ring method for dismantling and installing the blast furnace shell by dividing it into rings, and the single block method for pulling out the old blast furnace and pulling in the new blast furnace as one. , It can be applied to the blast furnace refurbishment method of various construction methods.

1 blast furnace 2 foundation 3 floor beam 4 furnace body 4A bottom mantel 4B upper mantel 4B1 morning glory 4B2 furnace belly 4B3 furnace chest 4B4 furnace throat 4B5 furnace top 5 iron shell 6A, 6B refractory Ri residual iron ingot C contents AP Opening CH Hole DM Drilling machine CP Cooling pipe Hi Injection port W Cooling water MP Supply unit EP Exhaust pipe

Claims (9)

Drilling is started from the outer peripheral side surface of the bottom of a blast furnace consisting of a refractory layer and residual pig iron deposits deposited on the refractory layer, and a plurality of bottomed holes are formed from the drilling start position toward the outer peripheral side surface on the opposite side. drilling a hole;
inserting a cooling pipe into each of the plurality of bottomed holes;
a step of injecting cooling water through the cooling pipe into each of the plurality of bottomed holes to cool the residual pig iron ingot in the blast furnace;
A bottom cooling method in blast furnace refurbishment, characterized by comprising: 2. The bottom cooling method in blast furnace refurbishment according to claim 1, wherein the bottomed hole is bored in the residual iron lump. 2. The method for cooling the bottom of a blast furnace in refurbishing a blast furnace according to claim 1, wherein the bottomed hole is bored in the refractory layer. 4. The bottom cooling method for blast furnace refurbishment according to claim 3, wherein the plurality of bottomed holes are arranged along the bottom of the residual iron lump when viewed from the front of the outer peripheral side surface of the furnace bottom. . A step of determining an opening range in a part of the shell provided on the outer peripheral side surface of the bottom of the blast furnace;
a step of removing the steel shell within the opening range before drilling the bottomed hole;
The bottom cooling method in blast furnace refurbishment according to any one of claims 1 to 4, characterized by comprising: The bottom cooling method in blast furnace refurbishment according to any one of claims 1 to 4, wherein the bottomed hole is drilled through an iron shell provided on the outer peripheral side surface of the hearth of the blast furnace. The blast furnace refurbishment according to any one of claims 1 to 6, wherein the plurality of bottomed holes are radially arranged so as to spread in a drilling direction of the bottomed holes in a plan view. bottom cooling method in The blast furnace refurbishment according to any one of claims 1 to 7, wherein the plurality of bottomed holes are formed obliquely downward in a drilling direction of the bottomed holes in a cross-sectional view. bottom cooling method in The diameter of the cooling pipe is smaller than the diameter of the bottomed hole, the tip surface of the cooling pipe is closed, and the cooling water injected into the cooling pipe is sprayed to the outside on the outer peripheral side surface of the cooling pipe. A plurality of injection holes are formed along the extending direction of the cooling pipe, and the cooling pipe is inserted into the bottomed hole so that the plurality of injection holes face the residual iron lump. The bottom cooling method in blast furnace refurbishment according to any one of claims 1 to 8, characterized in that:

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