JP7135779B2 - Work environment temperature reduction method when repairing a large bell - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for reducing the working environment temperature during repair of a large bell in a bell-type blast furnace, which reduces the atmospheric temperature of the working environment above the large bell when repairing the large bell.

In a blast furnace, raw materials such as iron ore and coke are charged from the upper part of the furnace, and high-temperature air and reducing agents such as pulverized coal are blown through the tuyeres at the lower part of the furnace to raise the temperature of the iron ore and reduce it to produce molten iron. is a reaction vessel that produces The bell-type blast furnace top charging device is mainly of the two-bell one-valve seal type, which consists of two bells, a large bell and a small bell, and a seal valve. The large bell is usually made of low-alloy cast iron, and hard facing or liner material is attached to the part where the falling raw material collides as a countermeasure against wear. However, even if such wear countermeasures are taken, wear of the large bell cannot be completely prevented, and progress of wear worsens the distribution of the contents in the furnace, leading to deterioration of the furnace conditions. Therefore, when the large bell wears out, repair such as hardfacing welding or replacement of the liner material is required.

Regarding the repair of the large bell, for example, Patent Literature 1 discloses a method for determining when to repair the large blast furnace bell. Patent document 2 discloses a liner used for repairing a large bell.

JP-A-6-287612 Japanese Utility Model Laid-Open No. 7-2458

Repair of the large bell is performed by workers entering the area surrounded by the large and small bells and working on the large bell when the blast furnace is closed. When the blast furnace is in operation, the ambient temperature above the large bell is 100°C or higher. The area surrounded by the large bell and the small bell has a narrow opening and is in a situation where the internal atmosphere tends to stay, so the high temperature state tends to continue. For this reason, the temperature in the area surrounded by the large bell and the small bell does not drop immediately even if the wind is cut off. Working in a high ambient temperature where the temperature does not drop sufficiently increases the risk of heatstroke for workers, and it is difficult to work continuously for a long time, so it takes a long time to repair. become.

On the other hand, if you wait for the temperature in the area surrounded by the large and small bells to drop before you start repairing, it will take time for the temperature to drop and the blast furnace will be damaged. The wind break time is long. If the blast furnace is closed for a long period of time, production loss will increase, the amount of reducing agent used for heat compensation during the closed period will increase, and there are concerns that it will increase operational instability at the time of start-up. . Therefore, there is a need for a technique for quickly reducing the temperature of the area surrounded by the large and small bells.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to quickly reduce the temperature of the area surrounded by the large bell and the small bell when repairing the large bell of the blast furnace. To provide a new and improved work environment temperature reduction method for repairing a large bell.

In order to solve the above problems, according to one aspect of the present invention, there is provided a method for reducing the work environment temperature during repair of a large bell in a top charging device for a bell-type blast furnace, wherein the top charging device comprises: a storage hopper that temporarily stores the water, a small bell provided below the storage hopper, and a large bell provided below the small bell, and when the large bell is repaired, the large bell and The distance from the surface of the charging material in the furnace is set to 5 m or more, the bell hopper body in the second region between the large bell and the small bell, which is a working environment, is partly opened, and the small bell and the A work environment temperature reduction method during repair of a large bell is provided, wherein the first area between the storage hopper and the second area are communicated with each other.

A portion of the bell hopper main body in the first area may be opened to connect a suction device, and the suction device may be operated to forcibly exhaust air from the second region communicating with the first region.

Furthermore, a cool air supply device may be connected to a part of the bell hopper main body where the second area is open, and the cold air supply apparatus may be operated to send cold air to the second area.

As described above, according to the present invention, the temperature of the region surrounded by the large bell and the small bell can be quickly reduced when repairing the large bell of the blast furnace.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing a schematic configuration of a top charging device for a bell-type blast furnace according to an embodiment of the present invention; It is an explanatory view explaining the conventional large bell repair work. 5 is a flow chart showing the work process of the work environment temperature reduction method when repairing a large bell according to the present embodiment. FIG. 4 is an explanatory diagram showing the flow of air in a blast furnace when repairing a large bell according to the present embodiment; FIG. 10 is a graph showing the relationship between the elapsed time after the wind break and the ambient temperature of the second region when the distance H between the large bell and the surface of charged raw material is changed. FIG. FIG. 5 is an explanatory view showing an example in which a suction device is installed by partially opening a first region surrounded by a small bell and a seal valve in the state of the top charging device shown in FIG. 4; FIG. 5 is an explanatory view showing an example in which a cold air supply device is installed in the opening of the second region in the state of the furnace top charging device shown in FIG. 4; FIG. 5 is an explanatory view showing an example in which a suction device and a cold air supply device are installed in the state of the furnace top charging device shown in FIG. 4;

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

<1. Configuration of top charging device for bell type blast furnace>
First, based on FIG. 1, a schematic configuration of a top charging apparatus for a bell-type blast furnace according to an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a schematic configuration of a top charging apparatus for a bell-type blast furnace according to the present embodiment.

A furnace top charging device 1 for charging raw materials such as iron ore and coke from the furnace top in a bell-type blast furnace is installed above the furnace body 9, and as shown in FIG. It has a valve 20 , a small bell cup 31 , a large bell cup 33 , a small bell 40 and a large bell 50 .

The storage hopper 10 is provided at the top of the furnace and temporarily stores the raw material conveyed by a conveyor (not shown). The top charging device 1 shown in FIG. 1 comprises four storage hoppers 10 . Two storage hoppers 10 are shown in FIG. The seal valve 20 is provided below the storage hopper 10 and separates the storage hopper 10 and the small bell 40 . The opening and closing of the seal valve 20 controls the supply of the material stored in the storage hopper 10 onto the small bell 40 .

The small bell 40 and the large bell 50 are members provided in the bell hopper main body 3 of the blast furnace, and are members for charging the raw material charged from the storage hopper 10 toward the region inside the furnace in stages. The small bell 40 has a shape that protrudes toward the top of the furnace, such as the substantially hemispherical or conical shape shown in FIG. Above the small bell 40, a small bell rod 43 extends in the furnace height direction toward the furnace top. The small bell rod 43 consists of a hollow member. The small bell 40 is moved up and down in the furnace height direction by raising and lowering the small bell rod 43 . The large bell 50 is provided below the small bell 40 and, like the small bell 40, has a substantially hemispherical or conical shape as shown in FIG. Above the large bell 50, a large bell rod 53 extends in the furnace height direction toward the furnace top. The large bell rod 53 is inserted through the small bell rod 43 . The large bell 50 is moved up and down in the furnace height direction by raising and lowering the large bell rod 53 .

Further, inside the bell hopper main body 3, a small bell cup 31 is provided corresponding to the height position of the small bell 40 in the furnace height direction, and a large bell cup 31 is provided corresponding to the height position of the large bell 50. A cup 33 is provided. A region formed by the small bell 40, the small bell cup 31, the bell hopper main body 3, and the seal valve 20 is defined as a "first region A1", and the large bell 50, the large bell cup 33, the bell hopper main body 3, the small bell 40, and the area formed by the small bell cup 31 is referred to as a "second area A2".

The outer surface of the small bell 40 abuts against the small bell cup 31 when the small bell 40 is raised, thereby separating the first area A1 and the second area A2. Such a state is also called a closed state. On the other hand, when the small bell 40 descends and the contact between the outer surface and the small bell cup 31 disappears, the first area A1 and the second area A2 are brought into communication. Such a state is also called an open state. Similarly, the outer surface of the large bell 50 abuts against the large bell cup 33 when the large bell 50 is raised, and separates the second area A2 from the in-furnace space A3. Such a state is also called a closed state. On the other hand, when the large bell 50 descends and the contact between the outer surface and the large bell cup 33 disappears, the second area A2 and the furnace space A3 are communicated with each other. Such a state is also called an open state.

In the first area A1, the internal pressure is increased to the blast furnace internal pressure in the closed state. The raw material pressurized to the pressure inside the blast furnace is charged into the second area A2 by lowering the small bell 40 . The second area A2 is an area for storing the raw material pressurized to the pressure inside the blast furnace. By lowering the large bell 50, the raw material is charged from the second area A2 into the furnace space A3.

Further, a manhole 3a is provided on a part of the side wall of the bellhopper main body 3 in the second area A2 so that it can be opened and closed with respect to the bellhopper main body 3. As shown in FIG. When the manhole 3a is closed, the second area A2 is isolated from the outside, and when the manhole 3a is open, the second area A2 and the outside are communicated.

<2. Work environment temperature reduction when repairing large bell>
[2-1. Overview]
The repair of the large bell 50 is performed by a worker entering the second area A2, which is a work environment surrounded by the large bell 50 and the small bell 40, and working on the large bell 50 when the blast furnace is closed. As described above, the temperature of the second area A2 is difficult to drop, and it takes time to reach a temperature at which the worker can work for a long period of time.

In the conventional repair work of the large bell 50, for example, as shown in FIG. 2, the large bell 50 is first fixed in a closed state after the blast furnace is shut down. Next, after the scaffold material 7 is charged from the storage hopper 10 into the closed small bell 40 , the small bell 40 is opened and charged into the large bell 50 . The scaffolding material 7 charged to the large bell 50 is laid on the large bell 50 except for the repaired portion. After that, the large bell 50 is repaired while the surface 5a of the charged raw material 5 in the furnace is ignited (furnace top fire). In addition, the top fire of the furnace is used to detoxify the blast furnace gas (CO gas) remaining in the furnace when the blast furnace is closed (CO → CO ₂ ). It refers to igniting and burning blast furnace gas by inserting an ignition burner into 5a) or inserting maki or the like.

In order to lower the ambient temperature of the second area A2 surrounded by the large bell 50 and the small bell 40, it is first necessary to exhaust the high temperature air from the area. Therefore, for example, the manhole 3a provided on the side wall of the bell hopper main body 3 in the second area A2 is opened to take in outside air into the second area A2, and the small bell 40 is opened to allow the high temperature air in the second area A2 to flow. It is conceivable to lower the ambient temperature of the second area A2 by forming the outlet. However, as a result of verification by the inventor of the present application, it was not possible to sufficiently lower the ambient temperature of the second region A2 only by such measures.

Therefore, as a result of investigating the reason why the atmosphere temperature in the second area A2 does not decrease, it was found that the large bell 50 was heated by the radiant heat from the furnace top fire, making it difficult for the atmosphere temperature in the second area A2 to decrease. Based on this knowledge, the inventors of the present application have found that it is necessary to secure a predetermined distance or more between the large bell 50 and the furnace top flame position in order to lower the ambient temperature of the second area A2. Hereinafter, the method for reducing the work environment temperature when repairing a large bell according to the present embodiment will be described in detail.

[2-2. Working process]
A method for reducing the working environment temperature during repair of a large bell according to the present embodiment will be described with reference to FIGS. 3 to 5. FIG. FIG. 3 is a flow chart showing the work steps of the work environment temperature reduction method for repairing a large bell according to the present embodiment. FIG. 4 is an explanatory diagram showing the flow of air in a blast furnace during repair of a large bell according to this embodiment. FIG. 5 is a graph showing the relationship between the elapsed time after the wind break and the ambient temperature of the second region A2 when the distance H between the large bell 50 and the charging material surface 5a is changed. 5 shows the relationship when the manhole 3a is open and the small bell 40 is open.

First, as shown in FIG. 3, after securing a distance H of 5 m or more between the large bell 50 and the charged raw material surface 5a, the air is stopped (S10). The distance H between the large bell 50 and the charged raw material surface 5a is the distance from the lower end of the large bell 50 to the charged raw material surface 5a, as shown in FIG. The height position of the charging material surface 5a may be the height position at the center of the blast furnace, or may be the average height position of the charging material surface 5a.

In the present embodiment, the target is to set the ambient temperature of the second region A2 to 40° C. or lower 12 hours after the blast furnace is shut down. FIG. 5 shows the result of examining the distance H required to achieve such a target. In FIG. 5, when the distance H between the large bell 50 and the charging material surface 5a was set to 3 m, 4 m, 5 m, and 6 m, the manhole 3a provided on the side wall of the second area A2 was opened after the wind was stopped. , and the ambient temperature of the second region was measured with the small bell 40 in the open state. As a result, in order to make the ambient temperature in the second area A2 40° C. or lower 12 hours after the blast furnace is closed, it is necessary to secure a distance H of 5 m or more between the large bell 50 and the charging material surface 5a. all right.

Based on this result, in step S10, after closing the large bell 50 and stopping the charging of the raw material into the bell hopper main body 3, the distance H between the large bell 50 and the charging raw material surface 5a becomes 5 m or more. stand by. Then, when the distance H between the large bell 50 and the charged material surface 5a becomes 5 m or more, the air is closed. Thereby, radiant heat from the furnace top fire to the large bell 50 is suppressed, and it is possible to suppress the atmospheric temperature of the second area A2 from being maintained at a high temperature.

Next, the scaffolding material 7 is placed on the large bell 50 fixed in the closed state (S20). After the scaffold material 7 is charged from the storage hopper 10 into the closed small bell 40 , the small bell 40 is opened and charged into the large bell 50 . The scaffolding material 7 charged to the large bell 50 is laid on the large bell 50 other than the repaired portion. The scaffolding material 7 is, for example, the charging material 5 to the blast furnace such as coke.

Further, the small bell 40 is fixed in the open state to allow communication between the second area A2 and the first area A1 (S30). At this time, the seal valve 20 is also opened. As a result, the air in the first area A1 moves to the second area A2 through the gap 37 between the small bell 40 and the small bell cup 31, and then passes through the seal valve 20 and moves out of the storage hopper 10. A flow path is formed for Therefore, the outside air that has flowed into the second area A2 from the opening 35 of the manhole 3a is discharged from the second area A2 along the flow path.

After that, the top of the furnace is ignited (S40), and the process waits until the ambient temperature of the second area A2 becomes equal to or lower than a predetermined temperature (S50). The predetermined temperature is a temperature that causes less load on the worker P, and may be 40° C., for example. When it is determined in step S50 that the ambient temperature in the second area A2 has become equal to or lower than the predetermined temperature, the worker P starts repairing the large bell 50 in the second area A2 (S60). Note that the furnace top fire may be performed before S30.

The method for reducing the work environment temperature during repair of a large bell according to the present embodiment has been described above. According to this embodiment, when repairing the large bell 50, the manhole 3a is opened while the distance H between the large bell 50 and the charged material surface 5a is 5 m or more, and the small bell 40 is opened. and As a result, the influence of radiant heat on the large bell 50 due to the furnace top fire is reduced, and the atmosphere temperature of the second area A2 is easily lowered, and from the opening 35, the second area A2, the first area A1, the seal valve By forming an air flow toward the storage hopper 10 through the 20, the hot air in the second area A2 can be easily discharged. As a result, the temperature of the second area A2 surrounded by the large bell 50 and the small bell 40 can be reduced early.

[2-3. Modification]
As shown in FIG. 4, the manhole 3a is opened while the distance H between the large bell 50 and the charging material surface 5a is 5 m or more, and the small bell 40 is opened. It is possible to effectively reduce the ambient temperature of the second area A2 during bell repair. In order to further enhance the reduction effect, it is possible to form a stronger air flow or supply cold air. A specific description will be given below.

(1) Utilization of Suction Device FIG. 6 shows, in the state of the top charging device 1 shown in FIG. The example which installed the apparatus 60 is shown. The suction device 60 is, for example, a dust collector or the like, and is connected by a pipe 65 at the opening 39 of the first area A1. The installation and operation of the suction device 60 may be performed, for example, after the furnace top fire in step S40 shown in FIG. At this time, the seal valve 20 is closed. The distance H between the large bell 50 and the charged raw material surface 5a is also ensured to be 5 m or more.

In this way, by operating the suction device 60 and sucking the air in the first region A1, the air flowing into the second region A2 and the first region A1 from the opening 35 is prevented from flowing toward the suction device 60. Can be made stronger. Therefore, the high-temperature air in the second area A2 is more easily discharged from the area.

(2) Use of Cool Air Supply Device FIG. 7 shows an example in which a cold air supply device 70 is installed in the opening 35 of the second area A2 in the state of the furnace top charging device 1 shown in FIG. The cold air supply device 70 is connected by a pipe 75 to the opening 35 of the second area A2. The installation and operation of the cold air supply device 70 may be performed, for example, after the furnace top fire in step S40 shown in FIG. The distance H between the large bell 50 and the charged material surface 5a is also ensured to be 5 m or more.

In this way, by operating the cold air supply device 70 and supplying cold air to the second area A2, from the opening 35, through the second area A2, the first area A1, the seal valve 20, the storage hopper The air flow towards 10 can be made stronger and the hot air can be cooled more effectively. Therefore, the high-temperature air in the second area A2 is more easily discharged from the area.

Furthermore, both the suction device 60 shown in FIG. 6 and the cool air supply device 70 shown in FIG. 7 may be used. FIG. 8 shows an example in which the suction device 60 and the cold air supply device 70 are installed in the state of the furnace top charging device 1 shown in FIG. The installation and operation of the suction device 60 and the cold air supply device 70 may be performed, for example, after the furnace top fire in step S40 shown in FIG. At this time, the seal valve 20 is closed. The distance H between the large bell 50 and the charged raw material surface 5a is also ensured to be 5 m or more.

In this case, the hot air can be cooled more effectively by operating the cold air supply device 70 to supply cold air to the second area A2. In addition, by operating the suction device 60 and the cool air supply device 70, the air flowing into the second area A2 and the first area A1 from the opening 35 can form a stronger flow toward the suction device 60. can. Therefore, the high-temperature air in the second area A2 is more easily discharged from the area.

In order to verify the effect of the present invention, the temperature of the second region surrounded by the large bell and the small bell, which is the work environment for repairing the large bell, was changed while the temperature of the second region was changed. We investigated the change in the ambient temperature of the In this verification, the distance H between the large bell and the charged raw material surface, the presence or absence of opening of the second area (that is, the open/close state of the manhole 3a in FIG. 1), the open/close state of the small bell, the installation of the suction device and the cold air supply device Changed the on/off setting. Incidentally, the atmospheric temperature was 25°C.

In Example 1, as shown in FIG. 4, the distance H between the large bell and the charged raw material surface was 5 m, and the atmosphere temperature in the second area was lowered while the second area and the small bell were open. let me At this time, the seal valve was opened.

In Example 2, as shown in FIG. 6, the distance H between the large bell and the charged raw material surface was secured to 5 m, the second area and the small bell were opened, and a suction device was installed to open the second area. The ambient temperature was lowered. At this time, the seal valve was closed.

In Example 3, as shown in FIG. 8, the distance H between the large bell and the charged raw material surface was secured to 5 m, the second area and the small bell were opened, and a suction device and a cold air supply device were installed. , the ambient temperature of the second region is lowered. At this time, the seal valve was closed.

On the other hand, in Comparative Example 1, a distance H of 5 m was secured between the large bell and the charged raw material surface, the small bell was opened to allow communication between the second region and the first region, and the suction device was installed in the first region. The ambient temperature in two zones was lowered. In Comparative Example 1, the second area was not opened, and the manhole 3a in FIG. 1 was closed. Also, in Comparative Example 1, no cold air supply device was installed.

In Comparative Example 2, a distance H of 5 m was secured between the large bell and the charged raw material surface, and the ambient temperature of the second area was lowered while the second area was opened and a cold air supply device was installed. In Comparative Example 2, the small bell was not opened.

In Comparative Example 3, the distance H between the large bell and the charged raw material surface was set to 4.1 m and less than 5 m, and as shown in FIG. was installed to lower the ambient temperature of the second region. At this time, the seal valve was closed.

For these Examples 1 to 3 and Comparative Examples 1 to 3, the ambient temperature in the second region was measured 12 hours after the cooling. Such results are shown in Table 1. In addition, in this verification, the target was to set the ambient temperature in the second region to 40° C. or less 12 hours after the blast furnace was shut down.

As shown in Table 1, in all of Examples 1 to 3, the ambient temperature in the second region became 40° C. or less 12 hours after the blast furnace was shut down. By providing a suction device as in the second embodiment, the ambient temperature in the second region can be further lowered. Further, as in the third embodiment, by providing a cold air supply device in addition to the suction device, the effect is further improved. Therefore, the ambient temperature in the second region could be effectively lowered.

On the other hand, in Comparative Example 1, a distance H of 5 m was secured between the large bell and the charged raw material surface, and the small bell was in an open state, but the second region was not opened. For this reason, the high-temperature air in the second zone was not effectively discharged, and the ambient temperature in the second zone remained higher than 40°C 12 hours after the blast furnace was shut down.

Similarly, in Comparative Example 2, the distance H between the large bell and the charged raw material surface was ensured to be 5 m, and the second region was in an open state, but the small bell was not opened. For this reason, the high-temperature air in the second zone was not effectively discharged, and the ambient temperature in the second zone remained higher than 40°C 12 hours after the blast furnace was shut down.

In Comparative Example 3, the second region and the small bell were open, but the distance H between the large bell and the surface of the charged raw material was less than 5 m. The situation was such that the ambient temperature in the second region was difficult to decrease. For this reason, the ambient temperature in the second zone remained higher than 40°C 12 hours after the blast furnace was shut down.

From the above, by securing the distance H between the large bell and the charged raw material surface of 5 m or more and opening the second region and the small bell, the temperature of the region surrounded by the large bell and the small bell can be quickly raised. It has been shown to reduce

Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. It is understood that these also naturally belong to the technical scope of the present invention.

1 top charging device 3 bell hopper main body 3a manhole 5 charged raw material 5a charged raw material surface 7 scaffolding material 9 furnace body 10 storage hopper 20 seal valve 31 small bell cup 33 large bell cups 35, 39 opening 37 gap 40 small Bell 43 Small bell rod 50 Large bell 53 Large bell rod 60 Suction device 65, 75 Piping 70 Cool air supply device

Claims (3)

A work environment temperature reduction method during repair of a large bell in a top charging device of a bell-type blast furnace,
The top charging device is
a storage hopper that temporarily stores raw materials;
a small bell provided below the storage hopper;
a large bell provided below the small bell;
and
When repairing the large bell,
The distance between the large bell and the surface of the charged raw material that is ignited at the top of the furnace is set to 5 m or more,
A part of the bell hopper main body in the second region between the large bell and the small bell that serves as a work environment is opened, and the small bell is lowered to move the second region between the small bell and the storage hopper. A work environment temperature reduction method when repairing a large bell, wherein the first area and the second area are communicated with each other. A part of the bell hopper body in the first area is opened to connect a suction device,
2. The method for reducing work environment temperature during repair of a large bell according to claim 1, wherein said suction device is operated to forcibly exhaust said second area communicating with said first area. connecting a cold air supply device to a part of the bell hopper main body opened in the second area;
3. The method for reducing work environment temperature during repair of a large bell according to claim 1, wherein said cold air supply device is operated to send cold air into said second area.

Images