JP2021025059A - Method of extending hot blast pipe and method of constructing additional hot blast stove - Google Patents

Abstract

To provide a method of extending a hot blast pipe and a method of constructing an additional hot blast stove capable of minimizing a shutdown period of a blast furnace.SOLUTION: The present invention provides a method of extending the hot blast pipe connected with the blast furnace and existing hot blast stoves and connecting the same to an additional hot blast stove, in which a portion of the hot blast pipe is opened and a connecting pipe that communicates with the hot blast pipe is installed, and a blocking pipe whose inside is closed with a blocking plate is connected to the connecting pipe in a preparatory step S1, an extension pipe is installed from the blocking pipe to the additional hot blast stove in an extension step S2, and the blocking pipe is removed from between the connecting pipe and a communication pipe, whose inside communicates between the connection pipe and the extension pipe, is installed so as to communicate the connecting pipe with the extension pipe, in a communication step S3.SELECTED DRAWING: Figure 4

Description

The present invention relates to a method of extending a hot air pipe and a method of expanding a hot air furnace.

In the iron-making blast furnace, a hot-air furnace for supplying hot air into the furnace is installed.
The hot air furnace is configured to include a combustion chamber and a heat storage chamber, and heats air in the combustion chamber and passes the heated air through the heat storage chamber to store heat in the heat storage bricks in the heat storage chamber. This air can be heated by passing air through a heat storage chamber that has sufficiently stored heat.
Normally, 3 to 5 hot air furnaces are provided for one blast furnace, and each hot air furnace is connected to the annular pipe of the blast furnace via a hot air pipe, and the hot air of the hot air furnace passes from the hot air pipe to the annular pipe and from the tuyere. It is supplied into the blast furnace. The hot air pipe is composed of a hot air main pipe leading to the blast furnace and a hot air branch pipe branching from the hot air main pipe to each hot air furnace.
In multiple hot air furnaces, combustion (heat storage) and ventilation (hot air supply) are alternately repeated in each hot air furnace, and the hot air furnaces are sequentially switched by the hot air valves installed in each hot air branch pipe to make a blast furnace. On the other hand, high-temperature air can always be continuously blown (see Patent Document 1).

In such a hot air branch pipe or a hot air main pipe connecting a hot air furnace and a blast furnace, a structure in which refractory bricks are stretched on the inner surface of a steel pipe material in order to withstand the high temperature (1100 to 1300 ° C.) hot air flowing inside. Will be adopted.
These refractory bricks are often partially or completely repaired when the inside of the hot air pipe is cooled to room temperature during the repair work of the blast furnace. However, in recent years, the life of the blast furnace has been extended to about 15 to 20 years, and the refractory bricks may be damaged or fall off during that period. If the refractory bricks are left as they are, the temperature of the iron skin rises, which in turn creates an opening in the iron skin, which may hinder the operation of the blast furnace. Therefore, if refractory bricks are damaged, urgent repair is required even during normal operation.

The only way to repair during normal operation is to have a worker enter the hot air pipe and repair the heat-resistant bricks during the regular repair (regular repair) of the blast furnace, which is carried out every one to two months.
Here, the regular repair time of the blast furnace is generally about 24 to 48 hours in order to avoid cooling of the blast furnace and the hot air furnace and to start up stably, and the maximum is 120 hours. In order to perform repairs, it is necessary to cool the inside of the hot air tube to a temperature that allows humans to enter.
However, even if the hot air is stopped, the temperature inside the hot air pipe does not drop immediately, and if the operator waits until the temperature is accessible, the time available for repair will be shortened.
On the other hand, for repairing the inside of the hot air pipe, which does not always occur during the life of the blast furnace, preparing a dedicated configuration such as an internal cooling device was not worth the equipment cost.
To solve such a problem, a technique has been proposed in which an existing configuration in a hot air furnace is used to take in outside air and form a flow for cooling the inside of the hot air pipe (see Patent Document 2).

JP-A-2007-262489 Japanese Unexamined Patent Publication No. 2013-224466

As described above, usually 3 to 5 hot blast furnaces are constructed for each blast furnace. On the other hand, even when not at the time of construction, depending on the blast furnace, it may be necessary to add a hot air furnace to the existing hot air furnace. For example, in order to increase the capacity of the blast furnace, it may be desired to improve the blowing capacity of the hot air furnace. In addition, when one of the hot blast furnaces is damaged, it is necessary to suspend and repair this hot blast furnace, but as a whole, the capacity of the blast furnace does not decrease even if one hot blast furnace is suspended. A hot air furnace may be added to secure the hot air supply capacity.
When adding a hot air furnace, for example, the hot air main to which the existing three units are connected is extended and connected to the additional one. When extending the hot air main, a part of the hot air main is cut open and the extension hot air pipe is connected to it. During this work, the internal temperature of the hot air main becomes a problem.

That is, when the blast furnace is in operation, the inside of the hot air main pipe has a high temperature of 1100 to 1300 ° C., and it is difficult to cut open a part of the hot air main pipe and connect the extended portion of the hot air pipe.
On the other hand, if the regular repair period of the blast furnace, that is, the time when the supply of hot air from the hot air furnace is stopped and the internal temperature of the hot air main is lowered, it is possible to connect the extension portion to the hot air main. However, the shutdown period of the blast furnace for periodic repair is limited as described above, and it is not sufficient for the work of cutting open the hot air main and installing an extension part leading to an additional hot air furnace.
For this reason, in order to extend the hot air main, it was common to carry out the repair work of the blast furnace where the blast furnace is suspended for a long period of time. During the repair work of the blast furnace, the hot air pipe is cooled to room temperature, so it can be easily connected. However, the repair period of the blast furnace is as long as 15 to 20 years, and there is a problem that a hot air furnace cannot be constructed during that period. Therefore, when the hot blast furnace is damaged, the temperature of the blast furnace is lowered due to the shutdown of the hot blast furnace, and an economic loss due to a decrease in the production capacity of the blast furnace is unavoidable.

An object of the present invention is to provide a method for extending a hot air pipe and a method for expanding a hot air furnace, which can minimize the shutdown period of the blast furnace.

The method of extending the hot air pipe of the present invention is a method of extending the hot air pipe to which the blast furnace and the existing hot air furnace are connected and connecting to the additional hot air furnace, and as a preparatory step, a part of the hot air pipe. Is opened to install a connecting pipe that communicates with the hot air pipe, and a shielding pipe whose inside is closed by a shielding plate is connected to the connecting pipe, and as an extension step, the shielding pipe reaches the additional hot air furnace. An extension pipe is installed, and as a communication step, the shielding pipe is removed from between the connection pipe and the extension pipe, and a communication pipe whose inside is open is installed between the connection pipe and the extension pipe. It is characterized in that the connecting pipe and the extension pipe are communicated with each other.

In such an invention, the work process of extending the hot air pipe and connecting it to the additional hot air furnace can be divided into three, a preparation process, an extension process, and a communication process.
Of the three steps, the hot air pipe needs to be temporarily opened in the preparation step and the communication step, but the hot air pipe is closed by the shielding pipe in the extension step in the middle. Therefore, it is possible to carry out the preparatory process during the regular repair period of the blast furnace, carry out the extension process with the blast furnace restarted, and carry out the communication process during the regular repair period of the blast furnace after the expansion of the hot air furnace is completed. .. As a result, it is not necessary to stop the blast furnace during the extension process with a long construction period, and the preparation process and the communication process can be carried out during another regular repair period, so the shutdown period of the blast furnace for extending the hot air pipe is minimized. This can substantially eliminate the long-term shutdown of the blast furnace for the purpose of extending the hot air pipe.
Further, in the present invention, the minimum modification range is set in order to minimize the shutdown period of the blast furnace. That is, in the preparatory process, only the terminal part of the hot air pipe needs to be removed and the connecting pipe is installed, and since the extension pipe has not been installed yet, the work from the outside is easy and the connection with the extension pipe is required. There is no need to adjust the length of the tube.
The additional hot air furnace connected to the extension pipe can be constructed prior to the preparatory process. In addition, a part of the extension pipe may be installed together with the additional hot air furnace prior to the preparation process.

In the extension method of the present invention, in the preparatory step, after opening a part of the hot air pipe, a heat shield is installed inside the opening of the hot air pipe, and the connection pipe communicating with the hot air pipe is installed. It is preferable to install the shielding pipe after removing the heat insulating plate.

In the present invention as described above, by installing the heat shield plate after opening a part of the hot air pipe, it is possible to shield the heat from the hot air pipe during the installation of the connection pipe and the construction work of the refractory. The preparatory process is carried out during the regular repair of the blast furnace, but the temperature of the hot air pipe is also high, and the radiant heat from the front exposes it to considerable heat during the work. However, by using the heat shield, the heat from the hot air pipe can be shielded, and the work of the preparation process can be advanced in a short time after the blast furnace is stopped.

In the method of extending a hot air pipe of the present invention, the connection pipe is formed with a connection shape on the side opposite to the hot air pipe and on the connection pipe side of the extension pipe, respectively, and is formed at both ends of the shielding pipe and the communication pipe. It is preferable to form a connected shape that can be connected to the connecting shape of the connecting pipe and the extension pipe, respectively.

In such an invention, the connection pipe and the extension pipe and the shielding pipe are connected, or the connection pipe and the extension pipe and the communication pipe are connected, depending on the connection shape and the connected shape. That is, since the shield pipe and the communication pipe have the same connected shape, both the shield pipe and the communication pipe can be reliably and efficiently connected to the connection pipe and the extension pipe.
Therefore, in the communication step, when the shielding pipe is separated from the connecting pipe and replaced with the communicating pipe, the work can be performed reliably and efficiently.
As the connection shape and the connected shape, a flange shape that can be bolted to face each other can be used. Further, the connection shape and the connected shape may be a shape that fits unevenly.

In the method for extending a hot air pipe of the present invention, it is preferable that a refractory material is installed on the connecting pipe side of the shielding plate and a water cooling structure is installed on the extension pipe side of the shielding plate.
The temperature of the shielding plate inside the shielding tube is high, and in order to withstand the temperature and pressure of the hot air tube, a refractory thickness of several hundred mm and a highly rigid shielding plate are required, and the length of the shielding tube is long. , Long and heavy.
On the other hand, in the present invention, by making the shielding plate portion a water-cooled structure, the thickness of the refractory can be reduced, the shielding tube becomes compact, and the final communication step becomes easy.

In the method for extending a hot air pipe of the present invention, it is preferable that a telescopic pipe is installed in the middle of the extension pipe.
In such a present invention, in order to remove the shielding pipe installed between the connecting pipe and the extension pipe in the communication process, it is necessary to widen the distance between the connecting portions. If a telescopic pipe is installed in the extension pipe, the shield pipe can be removed by expanding the distance between the extension pipe and the connecting portion of the shield pipe by shrinking the telescopic pipe with a jack or the like. After removing the shielding pipe, a communication pipe of the same length is installed, and the previously contracted telescopic pipe is returned to the original length, so that the extension pipe and the communication pipe can be connected.
As the expansion / contraction pipe, an expansion / contraction pipe for thermal expansion / absorption installed in the middle of the hot air pipe may be used, but if the distance from the communication pipe to the expansion / contraction pipe is long, it is large for expansion / contraction work. Since force is required, an expansion / contraction pipe dedicated to the communication process may be provided in a portion close to the connecting pipe. As a guide, when the distance from the communicating pipe to the telescopic pipe is longer than 8 m, it is preferable to install a dedicated telescopic pipe. As the telescopic tube, for example, a bellows tube or the like can be used.

The method for expanding the hot air furnace of the present invention is a method for expanding the hot air furnace in which the additional hot air furnace is connected to a part of the hot air pipe to which the blast furnace and the existing hot air furnace are connected via an extension pipe. Along with the construction, as a preparatory step, a part of the hot air pipe is opened to install a connecting pipe that communicates with the hot air pipe, and a shielding pipe whose inside is closed by a shielding plate is connected to the connecting pipe. As an extension step, an extension pipe from the shield pipe to the extension hot air furnace is installed, and after the extension hot air furnace can be constructed, the shield pipe is connected between the connection pipe and the extension pipe as a communication step. Is separated and removed, and a communication pipe having an open inside is installed between the connection pipe and the extension pipe to communicate the connection pipe and the extension pipe.
In such an invention, the effect as described in the above-described method for extending a hot air tube of the present invention can be obtained.

According to the present invention, it is possible to provide a method of extending a hot air pipe and a method of adding a hot air furnace that can minimize the shutdown period of the blast furnace.

The plan view which shows the blast furnace equipment before the addition of the hot blast furnace of one Embodiment of this invention. The plan view which shows the blast furnace equipment after the hot blast furnace expansion of the said embodiment. The schematic diagram which shows the work progress of the said embodiment. The flowchart which shows the construction procedure of the said embodiment. The schematic diagram which shows each procedure of the preparation process of said embodiment. The schematic diagram which shows the extension process and the communication process of the said embodiment. The cross-sectional view which shows the water-cooled structure of the shielding tube of the said embodiment. The front view which shows the water cooling structure of the shielding pipe of the said embodiment. The cross-sectional view which shows the shielding tube of another embodiment of this invention. The plan view which shows the blast furnace equipment of another embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, the hot air supply device 1 includes three hot air furnaces 11, 12, and 13 that generate hot air, and hot air generated by each of the hot air furnaces 11 to 13 is supplied to the blast furnace 3 via a hot air pipe 2. Will be done. Each of the hot blast furnaces 11, 12, and 13 is an external combustion type hot blast furnace having a mixed cooling furnace 111, 121, 131, a combustion furnace 112, 122, 132, and a heat storage furnace 113, 123, 133, respectively. However, each hot air furnace 11 to 13 may be of another type.
The hot air pipe 2 has a hot air main pipe 20 leading to the blast furnace 3, and the hot air main pipe 20 and the mixed cooling furnaces 111, 121, 131 of the hot air furnaces 11, 12, and 13 are hot air branch pipes 21, 22, respectively. It is tied at 23. In the hot air main pipe 20, expansion pipes 41, 42, 43 for thermal expansion absorption using bellows pipes are installed on the blast furnace 3 side of the connection portion of the hot air branch pipes 21, 22, 23.

In FIG. 2, in the present embodiment, one hot air furnace 14 (additional hot air furnace) is added to the three hot air furnaces 11 to 13 (existing hot air furnaces) installed in the hot air supply device 1. Then, in order to connect the hot air furnace 14 to the hot air main 20, an extension pipe 34 is connected to the end of the hot air main 20 to extend the hot air main 20.
The expansion work of the hot air furnace 14 and the extension work of the hot air main 20 are carried out separately from the operation of the blast furnace 3, but the connection work between the extension pipe 34 and the hot air main 20 is in a state where the blast furnace 3 is stopped. It cannot be carried out without it.

In FIG. 3, when the blast furnace 3 progresses to the blast furnace operation 1, the regular repair 1, the blast furnace operation 2, the regular repair 2, and the blast furnace operation 3, the hot air furnace 14 is used in the period from the blast furnace operation 1 or earlier to the regular repair 2. Carry out expansion work (construction of additional hot blast furnace). Further, the extension work of the hot air main 20 is carried out during the period from the regular repair 1 to the blast furnace operation 2 to the regular repair 2. The extension pipe 34 at a portion away from the hot air main 20 may be carried out before the blast furnace operation 1 together with the expansion work of the hot air furnace 14.
Of these, the extension procedure of the hot air main 20 includes a preparation step S1, an extension step S2, and a communication step S3. The preparatory step S1 is carried out within the period of regular repair 1, the extension step S2 is carried out within the period of blast furnace operation 2, and the communication step S3 is carried out within the period of regular repair 2.
FIG. 4 shows specific construction procedures S11 to S36 in the preparation step S1, the extension step S2, and the communication step S3.

In the preparation step S1, after the blast furnace 3 is temporarily stopped (procedure S11 in FIG. 4, fixed repair 1 in FIG. 3), the terminal of the hot air main 20 is excised and the surrounding refractory is removed (procedure S12). At this time, due to the dismantling of the refractory, hot air may be blown out when it penetrates the hot air main 20. Therefore, the bleeder pipe (not shown) installed in the hot air main 20 may be opened or an adjacent hot air furnace may be used. Therefore, it is better to avoid blowing hot air from the draft (see Patent Document 2).
Next, a heat shield 30 (described later) is installed inside the hot air main pipe 20 (procedure S13), a connecting pipe 31 (described later) is welded to the end opening (procedure S14), and a refractory material is placed inside the connecting pipe 31. Install (procedure S15). When the work inside the connecting pipe 31 is completed, the heat insulating plate is removed (procedure S16), and the shielding pipe 32 (described later) is connected to the connecting pipe 31 (procedure S17).
When these procedures S13 to S17 are completed, the operation of the blast furnace 3 is restarted (procedure S18, blast furnace operation 2 in FIG. 3).

FIG. 5 shows specific work contents in the preparation step S1.
In step S12, as shown in FIG. 5A, the end 201 of the hot air main 20 is cut off to form an opening 202, and as shown in FIG. 5B, heat is shielded inside the hot air main 20 through the opening 202. The board 30 is installed (procedure S13). As the heat insulating plate 30, for example, glass wool or the like which is nonflammable and has heat insulating properties and is molded into a plate shape can be used. The heat shield plate 30 blocks radiant heat from the hot air main pipe 20 and facilitates work inside the pipe on the opening 202 side. Then, the refractory 203 inside the hot air main 20 is removed from the opening 202 over a predetermined width.

In step S14, as shown in FIG. 5C, the connecting pipe 31 is welded to the opening 202 at the end of the hot air main pipe 20.
The connecting pipe 31 is a steel pipe having the same diameter as the hot air main pipe 20 but being short, and has a flange 311 (connection shape) on the side opposite to the side welded to the hot air main pipe 20. Although it is possible to form the flange 311 directly on the hot air main 20, it is difficult to weld the flange 311 perpendicularly to the outer peripheral surface of the hot air main 20 at the site, so the flange is attached to the connecting pipe 31 at the factory. It is better to weld 311 and then weld the connection pipe 31 and the hot air main pipe 20 to improve the mounting accuracy and work.
In step S15, as shown in FIG. 5D, the refractory material 312 is continuously installed from the inside of the connecting pipe 31 to the inside of the hot air main pipe 20 (the portion removed in step S13).

After removing the heat insulating plate 30 in step S16, in step S17, the shielding pipe 32 is connected to the connecting pipe 31 as shown in FIG. 5 (E).
The shielding pipe 32 is a short steel pipe having the same diameter as the hot air main pipe 20, and has a flange 321 (connected shape) on the side connected to the connecting pipe 31 and a flange 322 (connecting shape) on the opposite side. .. The flanges 321 and 322 have bolt holes having the same diameter and the same position as the flange 311 of the connecting pipe 31, and can be bolted to face each other.
A shielding plate 320 is installed inside the shielding tube 32. The entire circumference of the shielding plate 320 is welded to the inside of the shielding pipe 32, and when the shielding pipe 32 is connected to the connecting pipe 31, the end of the hot air main pipe 20 can be sealed in an airtight state.

7 and 8 show a specific structure of the shielding tube 32A used as the shielding tube 32 in the present embodiment.
In FIG. 7, a steel plate 51 is installed inside the shielding pipe 32A, and the above-mentioned shielding plate 320 is formed by the steel plate 51. A refractory material 53 such as a castable material is stretched on one side of the steel plate 51 (the surface on the connecting pipe 31 side). A large number of studs 54 for improving the biting property of the refractory 53 are arranged on the steel plate 51.
Another steel plate 52 is installed on the opposite side (extension pipe 34 side) of the steel plate 51, and a plurality of partition plates 55 and 56 are installed in the space between the steel plate 51 and the steel plate 52.

As shown in FIG. 8, the space between the steel plate 51 and the steel plate 52 is partitioned into a plurality of sections by the plurality of horizontal partition plates 55 and the vertical partition plate 56. A communication hole 57 is formed in each of the horizontal partition plates 55. An introduction pipe 58 and a discharge pipe 59 communicating with each other in the space between the steel plate 51 and the steel plate 52 are installed in the lower part and the upper part of the shielding pipe 32A.

In the shielding pipe 32A, a cooling structure is formed by these partition plates 55 and 56, communication holes 57, introduction pipe 58 and discharge pipe 59. The cooling water introduced from the introduction pipe 58 sequentially passes through the sections formed by the partition plates 55 and 56, and is discharged from the discharge pipe 59. At this time, the communication holes 57 are installed at positions where the vertically adjacent ones are separated from each other, and the cooling water passes through the sections formed by the partition plates 55 and 56 in a zigzag manner to cool the steel plate 51 (shielding plate 320). The effect can be enhanced.

In this way, during the period of regular repair 1, the end of the hot air main 20 opened in step S13 is sealed in an airtight state in step S17, so that the blast furnace 3 is operated in step S19 (blast furnace operation in FIG. 3). 2) It becomes possible to make it.
During the period of blast furnace operation 2, the extension step S2 is carried out.

In the extension step S2, the extension pipe 34 leading to the hot air furnace 14 (extended hot air furnace) is installed in the operating state of the blast furnace 3, and the refractory material is installed inside the extension pipe 34 (procedure S21 in FIG. 4).
FIG. 6 shows specific work contents in the extension step S2 and the communication step S3.
As shown in FIG. 6A, the shielding pipe 32 is connected to the connecting pipe 31 at the end of the hot air main 20 by the preparation step S1, and the hot air and radiation from the hot air main 20 are shielded even when the blast furnace 3 is in operation. Has been done.
As shown in FIG. 6B, the extension pipe 34 is installed so as to extend the hot air main pipe 20 from the end of the shielding pipe 32, and is connected to the hot air branch pipe 24 of the hot air furnace 14 to which the tip is added. ..

The extension pipe 34 is a steel pipe having the same diameter as the hot air main pipe 20, and has a flange 341 (connected shape) at an end facing the shielding pipe 32. The flange 341 has a bolt hole having the same diameter and the same position as the flanges 311, 321, 322 described above, and can be bolted to face the flange 322 of the shielding pipe 32.
A refractory 340 is installed on the entire surface of the extension pipe 34.
A telescopic tube 44 is formed in the middle of the extension tube 34.
The telescopic pipe 44 is formed of a bellows pipe or the like similar to the existing telescopic pipes 41, 42, 43 in the hot air main pipe 20.

In this way, by carrying out the extension step S2 during the period of the blast furnace operation 2, the extension pipe 34 from the shielding pipe 32 to the hot air furnace 14 is completed.
During the period of regular repair 2 following the blast furnace operation 2, the communication step S3 is carried out.

In the communication step S3, after the blast furnace 3 is temporarily stopped (procedure S31 in FIG. 4, fixed repair 2 in FIG. 3), the shielding pipe 32 is separated from the connecting pipe 31 and the extension pipe 34 and removed (procedure S32). At the time of separation, hot air may be blown out as described in the above-mentioned preparation step, so it is better to take a draft. Next, the communication pipe 33 (described later) is installed, connected to the connection pipe 31, and then the communication pipe 33 and the extension pipe 34 are connected (procedure S33).

As shown in FIG. 6C, the communication pipe 33 is installed so as to replace the portion between the connecting pipe 31 and the extension pipe 34 from which the shielding pipe 32 has been removed.
The communication pipe 33 is a short steel pipe having the same diameter and length as the shielding pipe 32 described above, has a flange 331 (connected shape) on the side connected to the connecting pipe 31, and a flange 332 (connected shape) on the opposite side. Connection shape). The flanges 331 and 332 are the same as the flanges 321 and 322 of the shielding pipe 32 described above, and can be bolted to face the flange 311 of the connecting pipe 31 and the flange 341 of the extension pipe 34.
The inside of the communication pipe 33 is communicated from the flange 331 side to the 332 side, and a refractory material 330 is installed on the entire surface inside the communication pipe 33.

Since the communication pipe 33 has the same size as the shielding pipe 32, the communication pipe 33 can be installed between the connecting pipe 31 and the extension pipe 34 after the shielding pipe 32 is removed. However, if there is no gap between each of the shielding pipe 32 and the communication pipe 33 when removing the shielding pipe 32 and when installing the communication pipe 33, the above-mentioned removal or installation work is difficult. Therefore, the telescopic pipe 44 formed in the extension pipe 34 is used to advance and retreat the flange 341 side of the extension pipe 34 to secure a work gap.

That is, when the shielding pipe 32 is removed (procedure S33), the extension pipe 34 is contracted to separate the flange 341 side of the extension pipe 34 from the shielding pipe 32, and between the shielding pipe 32 and the extension pipe 34. Secure a work gap. On the other hand, when the communication pipe 33 is installed (procedure S34), the extension pipe 34 is extended so that the flange 341 side of the extension pipe 34 is brought close to the communication pipe 33, the gap with the communication pipe 33 is eliminated, and each other is eliminated. Connect as close contact. Since the telescopic tube 44 is used to advance and retreat, care must be taken to keep the amount of advance and retreat to the minimum size of about 10 to 20 mm necessary for the work.

By performing the above communication steps S3, the hot air main pipe 20 is communicated with the connecting pipe 31, the communication pipe 33, and the extension pipe 34, and the hot air main pipe 20 is extended. Then, the hot air furnace 14 is connected to the hot air main 20, and the hot air furnace 14 (additional hot air furnace) can be added to the existing hot air furnaces 11 to 13.
When these procedures S31 to S33 are completed, the operation of the blast furnace 3 is restarted (procedure S34, blast furnace operation 3 in FIG. 3).

According to this embodiment, the following effects can be obtained.
In the present embodiment, in order to extend the hot air main 20 to which the blast furnace 3 and the hot air furnaces 11 to 13 (existing hot air furnace) are connected and connect them to the hot air furnace 14 (additional hot air furnace), the preparation step S1 and the extension step S2 and the communication step S3 were carried out.
As the preparation step S1, a part of the hot air main 20 was opened and a connecting pipe 31 communicating with the hot air main 20 was installed (procedure S14 in FIG. 4), and the inside of the connecting pipe 31 was closed by a shielding plate 320. The shielding tube 32 was connected (procedure S17).
As the extension step S2, an extension pipe 34 extending from the shielding pipe 32 to the hot air furnace 14 was installed (procedure S21).
As the communication step S3, the shielding pipe 32 is separated from the connecting pipe 31 and removed (procedure S32), and a communication pipe 33 having an open inside is installed between the connecting pipe 31 and the extension pipe 34, and the connecting pipe 31 is installed. And the extension pipe 34 were communicated with each other (procedure S33).

Thereby, in the present embodiment, the work step of extending the hot air main 20 and connecting it to the hot air furnace 14 can be divided into three steps: a preparation step S1, an extension step S2, and a communication step S3.
Of the three steps, the hot air main 20 needs to be temporarily opened in the preparation step S1 and the communication step S3, but the hot air main 20 is closed by the shielding pipe 32 in the extension step S2 in the middle. Therefore, the preparation step S1 is carried out during the periodic shutdown period of the blast furnace 3 (fixed repair 1 in FIG. 3), the extension step S2 is carried out with the blast furnace 3 restarted (blast furnace operation 2), and the next and subsequent shutdowns are performed. The communication step S3 can be carried out during the period (fixed repair 2).

As a result, it is not necessary to stop the blast furnace 3 during the extension step S2, which has a long construction period, and the preparation step S1 and the communication step S3 may be carried out during different stop periods (fixed repair 1 and fixed repair 2). The shutdown period for the extension of the main 20 can be minimized, and the shutdown of the blast furnace 3 for the purpose of extending the hot air main 20 can be substantially eliminated.

In the lower part of FIG. 3, when the blast furnace 3 is stopped for the purpose of extending the hot air main 20, the blast furnace 3 is stopped from the period of the blast furnace operation A, and the preparation step S1, the extension step S2, and the communication step S3 are performed during that period. All work procedures will be carried out. As a result, the suspension period from the completion of the extension to the start of the blast furnace operation B has to be lengthened.
On the other hand, in the present embodiment, as described above, the extension step S2 can be performed during the period of the blast furnace operation 2, and the preparation step S1 and the communication step S3 are carried out during different stop periods (fixed repair 1 and fixed repair 2). It is possible to minimize the downtime of the blast furnace 3. The preparatory step S1 is carried out using the regular repair period of the blast furnace 3, but if there is a plan to expand the hot air furnace in the future, it can be carried out during the repair work in which the blast furnace 3 is suspended for a long period of time. is there.

In the present embodiment, in the preparation step S1, the heat shield 30 is installed inside the opening of the hot air main pipe 20 before the connection pipe 31 is installed (procedure S13), and the heat shield 30 is removed before the shield pipe 32 is installed. (Procedure S16).
As a result, in the present embodiment, by installing the heat insulating plate 30 after opening a part of the hot air main 20, radiant heat from the hot air main 20 is generated during the work of installing the connecting pipe 31 and connecting the shielding pipe 32. Can be shielded. The preparatory step S1 is carried out when the blast furnace 3 is stopped (fixed repair 1), but the temperature inside the hot air main pipe 20 is also high, and it is exposed to considerable heat during the work. However, by using the heat shield 30, the heat from the hot air main 20 can be shielded, and the work of the preparation step S1 can proceed in a short time after the blast furnace 3 is stopped.

In the present embodiment, the connecting pipe 31 is formed with a flange 311 (connection shape) on the side opposite to the hot air main pipe 20, and the shielding pipe 32 and the communicating pipe 33 are connected to the connecting pipe 31, respectively. The flanges 321 and 331 (connected shape) that can be connected to the flange 311 are formed on the surface.
As a result, in the present embodiment, the connecting pipe 31 and the shielding pipe 32 are connected by the flange 311 and the flange 321 (procedure S17), and the connecting pipe 31 and the communicating pipe 33 are connected by the flange 311 and the flange 331. Connection is made (procedure S34). That is, since the flanges 321 and 331 (connected shapes) of the shielding pipe 32 and the communicating pipe 33 are common, both the shielding pipe 32 and the communicating pipe 33 can be reliably and efficiently connected to the connecting pipe 31.

Similarly, on the opposite sides of the shielding pipe 32 and the communicating pipe 33, flanges 322 and 332 (connected shape) common to the flanges 321 and 331 are formed, and the flange 341 (connecting shape) of the extension pipe 34 is formed therein. Since it is possible to connect to the flanges 322 and 332 of the above, the shielding pipe 32 and the communicating pipe 33 can be reliably and efficiently connected to the extension pipe 34 side as well.
Therefore, in the communication step S3, when the shielding pipe 32 is separated from the connecting pipe 31 and replaced with the communication pipe 33, the work can be performed reliably and efficiently.

In the present embodiment, the shielding pipe 32 is provided with a refractory 53 on the connecting pipe 31 side of the shielding plate 320 (steel plate 51 in FIG. 7), and the partition plates 55 and 56 are installed on the extension pipe 34 side of the shielding plate 320. , A water-cooled structure composed of a communication hole 57, an introduction pipe 58 and a discharge pipe 59 was installed.
The temperature of the shielding plate 320 inside the shielding tube 32 is high, and in order to withstand the temperature and pressure of the hot air tube, a refractory thickness of several hundred mm and a highly rigid shielding plate are required. The length is long and heavy.
On the other hand, in the present embodiment, by making the shielding plate 320 a water-cooled structure, the thickness of the refractory 53 can be reduced, the shielding tube 32 becomes compact, and the final communication step S3 can be facilitated.

In the present embodiment, the extension pipe 34 is formed with a telescopic pipe 44 in the middle.
As a result, in the present embodiment, when the shielding pipe 32 is separated from the connecting pipe 31 and removed (procedure S33) in the communication step S3, the expansion pipe 44 is contracted and the extension pipe 34 is separated from the shielding pipe 32. By shifting to, a working gap can be secured between the connecting pipe 31 and the shielding pipe 32 and between the shielding pipe 32 and the extension pipe 34.
Further, when the shielding pipe 32 is removed and replaced with the communication pipe 33 (procedures S34 to S35), the expansion pipe 44 is extended and the extension pipe 34 is displaced in the direction closer to the communication pipe 33 to form the connecting pipe 31. The gaps between the communication pipe 33 and the communication pipe 33 and the extension pipe 34 can be eliminated, and the connections can be ensured between the two.

The present invention is not limited to the above-described embodiment, and modifications within the range in which the object of the present invention can be achieved are included in the present invention.
In the above embodiment, as the shielding tube 32, the shielding tube 32A having the water-cooled structure shown in FIGS. 7 and 8 was used. However, the water-cooled shielding tube 32A is not essential to the present invention, and a non-water-cooled shielding tube 32B as shown in FIG. 9 may be used.

In FIG. 9, a steel plate 61 is installed inside the shielding pipe 32B, and the above-mentioned shielding plate 320 is formed by the steel plate 61. A refractory material 62 such as a castable material is stretched on one side of the steel plate 61 (the surface on the connecting pipe 31 side). A large number of studs 63 for enhancing the biting property of the refractory 62 are arranged on the steel plate 61.
Along the surface of the refractory 62, refractory bricks 64 are stacked in two layers. As a result, a refractory layer having a sufficient thickness is formed on the connecting pipe 31 side of the shielding pipe 32B.
A bracket 65 for supporting the steel plate 61 is welded to the opposite side of the steel plate 61 (extension pipe 34 side), and H-shaped steel 66 is assembled vertically and horizontally.

In the present invention, such a non-water-cooled shielding tube 32B may be used. However, since the water-cooled shielding pipe 32A described above is lighter and more compact, it is possible to easily replace the shielding pipe 32 and the communicating pipe 33, which is carried out in the communication step S3.
For example, when comparing the two, the non-water-aged type shielding pipe 32B had a length of about 800 mm and a weight of 12 tons, whereas the water-aged type shielding pipe 32A had a length of about 500 mm and a weight of about 500 mm. It can be reduced to 7 tons, which is about 60%.

In the above embodiment, in the shielding plate 320, the refractory material 53 is installed only on the connecting pipe 31 side, but the refractory material may also be installed on the extension pipe 34 side. When a refractory material is also applied to the extension pipe 34 side, it is effective when the extension pipe 34 is also intended to be dried when the hot air furnace 14 is started up.

In the above embodiment, the expansion work of the hot blast furnace 14 (construction of the additional hot blast furnace) is carried out during the period from the blast furnace operation 1 or earlier to the regular repair 1. The pre-construction prior to the preparatory step S1 is not limited to the construction of the hot air furnace 14, and may be carried out as long as it does not affect the operating state of the blast furnace 3, such as a part of the hot air branch pipe 24 or the extension pipe 34.

In the above embodiment, the flanges 311, 341 which are the connection shapes and the flanges 321, 322, 321 and 332 which are the connected shapes are used, and they are all the same shape, but the connection shape and the connected shape are different from each other. It may be in shape. Further, the connection shape and the connected shape are not limited to the flange shape, and may be a shape in which the surfaces are unevenly fitted to each other. In short, if the connected shapes formed in the shielding pipe 32 and the communicating pipe 33 are common, the work of replacing the shielding pipe 32 and the communicating pipe 33 can be efficiently performed.
Further, the connection shape and the connected shape (flange 311, 3211, 322, 331, 332, 341) are factory-installed on each pipe (connection pipe 31, shielding pipe 32, communication pipe 33, and extension pipe 34) in advance. It may be left in place or welded to the end of each pipe in the field.
The shielding plate 320 of the shielding tube 32 may be constructed in the factory in advance, or may be constructed on-site.
The refractory material 330 of the communication pipe 33 may be constructed in the factory in advance, or may be constructed in the field.

In the above embodiment, a working gap is secured when the shielding pipe 32 is separated from the connecting pipe 31 and removed by using the expansion pipe 44 for thermal expansion absorption formed in the middle of the extension pipe 34 (procedure S33). However, when the shielding pipe 32 was removed and replaced with the communication pipe 33 (procedures S34 to S35), the work gap was eliminated.
On the other hand, in the extension pipe 34, a telescopic pipe dedicated to the communication process may be provided in addition to the telescopic pipe 44 for measures against thermal expansion.

In FIG. 8, in another embodiment of the present invention, the distance from the telescopic pipe 44 of the extension pipe 34 to the end connected to the communication pipe 33 is longer than that of the embodiment. In such a case, in the communication step S3, when the shielding pipe 32 is separated from the connecting pipe 31 and removed (procedure S33), and when the shielding pipe 32 is removed and replaced with the communication pipe 33 (procedures S34 to S35). Since the length of the extension pipe 34 that displaces with the expansion and contraction of the expansion pipe 44 becomes long and the weight that displaces increases, the difficulty of work may increase. On the other hand, by providing the expansion pipe 45 dedicated to the communication process near the end of the extension pipe 34 on the shielding pipe 32 side, the length and weight from the same end to the expansion pipe 45 can be reduced, and the work can be performed. It is possible to easily secure and eliminate the gap.

The present invention can be used as a method for extending a hot air pipe and a method for expanding a hot air furnace.

1 ... Hot air supply device, 111, 121, 131, 141 ... Mixing and cooling furnace, 112, 122, 132, 142 ... Combustion furnace, 113, 123, 133, 143 ... Heat storage furnace, 11, 12, 13, 14 ... Hot air furnace 2, 2 ... hot air pipe, 20 ... hot air main, 201 ... end, 202 ... opening, 203 ... refractory, 21, 22, 23, 24 ... hot air branch pipe, 3 ... blast furnace, 30 ... heat shield, 31 ... connection pipe , 32 ... shielding pipe, 33 ... communicating pipe, 34 ... extension pipe, 311,341 ... flange (connection shape), 321,322,331,332 ... flange (connected shape), 312,330,340 ... refractory, 320 ... shielding plate, 41, 42, 43, 44, 45 ... expansion tube, 51, 61 ... steel plate constituting the shielding plate, 52 ... steel plate, 53, 62 ... refractory, 54, 63 ... stud, 55, 56, 57, 58, 59 ... Partition plate, communication hole, introduction pipe and discharge pipe, bracket, 64 ... refractory refractory brick, 65 ... bracket, 66 ... H-shaped steel, S1 ... preparation process, S2 ... extension process, S3 ... communication process.

Claims (6)

It is a method of extending the hot air pipe to which the blast furnace and the existing hot air furnace are connected and connecting to the additional hot air furnace.
As a preparatory step, a part of the hot air pipe is opened to install a connecting pipe communicating with the hot air pipe, and a shielding pipe whose inside is closed by a shielding plate is connected to the connecting pipe.
As an extension process, an extension pipe from the shielding pipe to the additional hot air furnace is installed.
As a communication step, the shielding pipe is removed from between the connection pipe and the extension pipe, and a communication pipe having an open inside is installed between the connection pipe and the extension pipe to form a communication pipe with the connection pipe. A method for extending a hot air pipe, which comprises communicating with the extension pipe. In the method for extending a hot air pipe according to claim 1,
In the preparatory step, after opening a part of the hot air pipe, a heat shield was installed inside the opening of the hot air pipe, the connection pipe communicating with the hot air pipe was installed, and the heat shield was removed. Later, a method of extending the hot air pipe, which comprises installing the shielding pipe. In the method for extending a hot air pipe according to claim 1 or 2.
The connection pipe is formed with a connection shape on the side opposite to the hot air pipe and on the connection pipe side of the extension pipe, respectively.
A method for extending a hot air pipe, characterized in that a connected shape that can be connected to the connection shape of the connection pipe and the extension pipe is formed at both ends of the shielding pipe and the communication pipe, respectively. In the method for extending a hot air pipe according to any one of claims 1 to 3,
The shielding pipe is a method for extending a hot air pipe, characterized in that a refractory is installed on the connecting pipe side of the shielding plate and a water cooling structure is installed on the extension pipe side of the shielding plate. In the method for extending a hot air pipe according to any one of claims 1 to 4.
A method of extending a hot air pipe, characterized in that a telescopic pipe is installed in the middle of the extension pipe. It is a method of adding a hot air furnace in which an additional hot air furnace is connected to a part of the hot air pipe to which the blast furnace and the existing hot air furnace are connected via an extension pipe.
In addition to constructing the additional hot air furnace
As a preparatory step, a part of the hot air pipe is opened to install a connecting pipe communicating with the hot air pipe, and a shielding pipe whose inside is closed by a shielding plate is connected to the connecting pipe.
As an extension process, an extension pipe from the shielding pipe to the additional hot air furnace is installed.
After the construction of the additional hot air furnace was completed,
As a communication step, the shielding pipe is separated and removed from between the connection pipe and the extension pipe, and a communication pipe having an open inside is installed between the connection pipe and the extension pipe to connect the connection pipe. A method for expanding a hot air furnace, characterized in that a pipe and the extension pipe are communicated with each other.

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