JPH0129844B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method of operating a blast furnace for iron-making. The present invention relates to a method of operating a blast furnace in which deposits formed on the furnace wall in the direction of the tuyere are removed by increasing or decreasing the amount of air blown from the tuyere branch pipe.

[Conventional technology]

Generally, a blast furnace for steelmaking has 30 to 40 tuyeres on the outer periphery of the lower part of the furnace for blowing high-temperature hot air into the furnace. 900-1300℃, humidity 7-50
Humidity-controlled hot air of about g/Nm ³ (maximum 60 g/Nm ³ ) is blown into the furnace.

On the other hand, the raw material ore is charged to form a uniform layer through a charging bell, movable armor, etc., and reacts in the furnace with high-temperature hot air blown from the lower part of the furnace, reducing, softening, and partitioning. After wearing and melting,
Hot metal is formed in the furnace pool, and is tapped from the tap hole 10 to 20 times a day.

In such a blast furnace operating method, due to non-uniform gas flow in the circumferential direction, the furnace wall 2 of the blast furnace 1
As shown in FIG. 1, deposits 18 are formed on a portion of the surface of the substrate due to solidification of the molten material or precipitates (for example, ZnO) from the gas phase.

These deposits 18 formed on the furnace wall are removed from the tuyere 6
further disrupting the uniformity of the blown gas flow,
The deposits 18 grow further and eventually fall in the furnace during operation, stopping the tuyere ventilation at the relevant locations and causing a wind outage.

The deposits formed on the walls of the blast furnace as described above cause malfunctions in the operating method of the blast furnace, so there has been a demand for the development of a method for removing them during operation.

In order to remove these in-furnace deposits that were conventionally formed on the walls of the blast furnace, movable armor was used.
Attempts have been made to locally transform the in-furnace gas flow into a peripheral flow to reduce and melt deposits. However, this attempt was not sufficient to remove the deposits, and changing the diameter of the tuyeres and increasing the speed of the tuyeres caused the gas flow in the furnace to flow to the center, which was somewhat effective, but the air had to be rested. It was not practical.

On the other hand, when changing the amount of air blown locally, the control valve for controlling the amount of air blown from each tuyere branch pipe of high-temperature hot air is difficult due to the material, and it is not possible to control the amount of air blown from each tuyere.

Conventionally, attempts have been made to use control valves made of metal valve bodies as flow rate control valves for these tuyeres, but the valve body lacks heat resistance and cannot withstand high temperatures, so water-cooling the valve body has also been adopted. However, the heat loss was large and it could not be put to practical use. Although water-cooled control valves or dampers were installed in the annular high-temperature hot air pipe to control the overall air flow, Controlling the amount of air blown from each tuyere had not yet been put into practical use.

As a hot air control valve to solve these above-mentioned problems, the applicant has proposed the
As shown in the figure, the valve plate 21 and valve stem 22 of the valve body 13
The application has been filed for a butterfly valve 8 in which the valve body is housed in a casing 31 which is lined with heat-resistant members 36 and 37 to form a flow path.

[Problem that the invention seeks to solve]

The present invention uses a method of operating a blast furnace to remove deposits formed on the furnace wall during operation by increasing or decreasing the amount of air blown through the tuyere using a hot air control valve installed in a tuyere branch pipe, thereby locally controlling the gas flow in the furnace. The object of the present invention is to provide a method for stabilizing blast furnace operation by reducing and melting away the deposits by causing the blast furnace to flow around the edges.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems. In other words, the above-mentioned application No. 57-170080
A heat-resistant hot air control valve made of ceramic and a further improved hot air control valve proposed in the above issue are installed in each tuyere branch pipe, and the hot air control valve is used to increase or decrease the air flow rate of each tuyere. This is a blast furnace operating method that generates a gas flow to reduce and melt the deposits and remove them.

That is, the gist of the present invention is that when high-temperature hot air is blown into the furnace from the furnace tuyeres via the tuyere branch pipes, a hot air control valve is provided for each tuyere branch pipe, and the hot air control valve controls the control of some of the tuyere branch pipes. This is a method of operating a blast furnace in which deposits formed on the furnace wall in the direction of the tuyere are removed by increasing or decreasing the amount of air blown.

However, the above-mentioned hot air control valve is a hot air control valve in which (i) the valve plate of the valve body and the valve stem are integrally constructed of ceramics, and (ii) the valve plate of the valve body and the valve stems provided above and below the valve plate. and a support shaft integrally made of ceramic; and an annular ceramic valve body having an inner diameter approximately equal to the flow path of high-temperature hot air and formed to rotatably support a lower portion of the valve body. a pair of support members, the support members being connected to the valve plate;
(iii) a cylindrical first heat resistant member and a cylindrical first heat resistant member fitted into the first heat resistant member longer than the first heat resistant member; A cylindrical second heat-resistant member is divided into two parts from the center, and these first and second heat-resistant members are inserted on both sides of a valve body disposed at the center of the casing to make the valve body rotatable. A hot air control valve that supports the first and second heat-resistant members, fits holding members on both sides of the heat-resistant member, has a stopper attached to the outer periphery of the second heat-resistant member, and welds the stopper to the inner wall of the casing to integrally connect them. (iv) In the hot air control valves of (ii) and (iii) above, the chamber formed between the valve stem of the valve body and the flange of the casing is drained through a passage provided in the flange. It is connected to the section.

etc. achieves the object of the present invention.

[Effect]

The air flow rate from the branch pipe of the tuyere installed at the bottom of the deposits formed on the blast furnace wall, which was difficult to control in the past, has been improved.
During operation, the hot air control valve composed of (i) to (iv) described above increases and decreases the amount of hot air to generate a local gas flow around the deposits, and this surrounding gas flow reduces and melts the deposits. Remove.

Normally, when the air flow rate of the tuyeres is reduced, the in-furnace gas flow forms a flow around the deposits. This formed surrounding gas flow melts and reduces the deposits.

Due to the above action, deposits formed on the walls of the blast furnace are removed, thereby making the gas flow uniform in the circumferential direction within the furnace, thereby stabilizing the operation of the blast furnace.

During blast furnace operation, the deposits formed on the furnace wall caused the "blow-through" of the gas in the furnace and the "hanging of the fence" phenomenon of the charge, which hindered stable operation. This made it possible to eliminate the "blow-through" and "fence-hanging" phenomena during blast furnace operation, achieving stable operation.

Specifically, the size of the deposits is estimated using a furnace temperature sensor, and in the case of strong deposits, the deposits are removed after approximately 5 to 10 days at approximately half the normal tuyere air flow rate. was recognized.

Furthermore, as the hot air control valve used in the blast furnace operating method of the present invention, the hot air control valve shown in FIGS. 4 to 6 in the embodiment described later has a strong valve body, a wide flow rate control range, and is easy to manufacture. This is suitable because it is easy to clean and has a drain removal mechanism.

Examples of embodiments of the present invention will be described below.

〔Example〕

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 is a diagram showing the arrangement of the taphole of a blast furnace, Fig. 3 is an explanatory diagram showing the arrangement of the tuyere, and Fig. 4 is an explanatory diagram of the installation of the hot air control valve. It is.

In the figure, 1 is a blast furnace, 2 is a furnace wall, 3 is a charging bell, 4: ore and coke, 5: furnace temperature sensor, 6: tuyere, 7: blast tuyere branch pipe, 8: hot air control valve, 9: Annular hot air pipe, 10: taphole, 11: sump, 12: calculation control device, 18: deposits.

900-1300 to react the ore and coke layer 4 charged into the blast furnace 1 through the charging bell 3.
℃ and absolute temperature of 7-50 g/Nm ³ is blown from the annular hot air pipe 9 through the tuyere branch pipe 7 and from the tuyere 6. The slag and pig iron reacted and generated in the furnace form a slag layer and a pig iron layer in the sump 11 in the lower part of the furnace, and are periodically passed through the tap hole 10 to the tap hole (not shown) to the large trough. be discharged.

In this embodiment, the tap holes (inner diameter 50 mmφ) are 10a, 10b, 10c, 10 as shown in FIG.
d, each taphole has its own blowing tuyere (tuyere diameter
A total of 40 tuyeres are arranged in 4 blocks (100-140mmφ) per block, and a hot air control valve 8 is provided for each tuyere branch pipe.

First, in removing deposits, which is the object of the present invention, abnormalities are detected in advance using blast furnace thermometers 5 installed in the circumferential direction and height direction of the furnace.

For example, when the temperature sensor 5 detects that 18 deposits are formed as shown in _FIG . By controlling the hot air control valves 8a ₆ - 8a ₈ provided for each of the tuyere branch pipes ₈ and reducing the amount of air blown, a local gas flow is generated around the deposits 18, and the deposits 18 are removed. Remove by melting reduction.

As a result of the removal of the deposits 18, there are no obstructions in the circumferential direction within the furnace, and the tuyere flow rate is returned to maintain proper blast furnace operation.

In this case, by comparing the value detected by the furnace temperature sensor 5 and the appropriate furnace temperature stored in the calculation control device 12, the presence of deposits in the furnace is confirmed, and the corresponding tuyere branch pipe, for example, 7a Even if the hot air control valve installed at _{6-7a 8} is automatically controlled, an alarm system (not shown) will notify the operator of any abnormality.
It may also be operated manually. By performing such an operation, it became possible to remove deposits inside the blast furnace, which had been considered difficult in the past, and proper blast furnace operation was maintained. Next, a hot air control valve for carrying out the method of the present invention will be described.

In the present invention, the butterfly valve as shown in FIG. 8 described above has high heat resistance and can be used practically as a hot air control valve 8 in the tuyere branch pipe 7.

However, the present applicant has further developed a hot air control valve in which the strength of the valve plate for opening and closing the flow path of the butterfly valve and the flow rate control range are greatly increased.

FIGS. 5 and 6 are a front view and a side view showing a part of the improved hot air control valve in cross section.

5 and 6, 8 is a hot air control valve, 13 is a valve body, 14 is a casing that accommodates the valve body, 15 is a drive section for the valve body 13, and 16 is a drive section 15.
This is the drain discharge section installed in the

In the valve body 13, 21 is a disc-shaped valve body, 22
23 is the valve shaft provided on the upper part of the valve plate 21, and 23 is the valve plate 21.
This is a support shaft provided at the lower part on the same line as the valve shaft 22, and these are integrally constructed of ceramics.

In the casing 14, 31 is a steel outer cylinder having flanges 32, 32a and 33 at both ends and the upper part, and the flange 33 has a passage opening into the chamber A formed between the flange 33 and the valve shaft 22. 3
4 are provided.

35 and 35a are support members made of ceramics that support the valve plate 21 from both sides of the valve plate 21 via bushes, and 36 and 36a have an outer diameter that is equal to the outer diameter of the outer cylinder 31.
3 with a cylindrical first heat-resistant member that matches the inner diameter of
7, 37a is a cylindrical second heat resistant member whose outer diameter matches the inner diameter of the first heat resistant member 36, 36a and is longer than the first heat resistant member 36, 36a; 38 is a hot air flow path;
39, 39a are cutout portions provided on the inner periphery of the opposing portion;
40, 40a are semicircular cutout portions provided above the cutout portions 39, 39a, through which the valve shaft 22 is inserted;
1, 41a is the first heat-resistant member 3 at the outer periphery of the end portion.
6, 36a are stepped portions cut out to the ends. 4
Reference numeral 2, 42a denotes a ring-shaped support member made of ceramics, the outer diameter of which is the same as that of the second heat-resistant members 37, 37a.
The inner diameter is formed to match the inner diameter of the second heat-resistant members 37, 37a and the diameter of the flow path 38.

43 and 43a are bushes. 44, 44a
is a ring-shaped holding member made of a heat-resistant material, the outer diameter of which matches the inner diameter of the outer cylinder 31, and the inner diameter of which matches the step portions 41, 41a of the second heat-resistant members 37, 37a;
L-shaped cutout portions 45, 45a are formed at the ends. Reference numerals 47 and 47a are ring-shaped steel fasteners that are attached to the cutout portions of the pressing members 44 and 44a via gland packings 48 and 48a, and are welded to the inner wall of the outer cylinder 31 to hold the above-mentioned parts inside the outer cylinder 31. be fixed in one piece.

In the drive unit 15, 51 is a motor, 52 is a cover that covers the connection between the output shaft of the motor 51 and the valve shaft 22, and a flange 53 is provided at the lower part. A hole 54 is provided which communicates with the passage 34 provided in the.

In the drain discharge section 16, 61 is a drain pipe whose one end is fixed to the flange 53 of the cover 52 and communicates with the hole 54, 62 is a valve provided on this pipe 54, and 63 is a stem supporting the pipe 61.

In the hot air control valve configured as described above, the control valve 8 is connected to the air flow passage of the tuyere air blowing branch pipe 7 of the tuyere 6 by the flanges 32, 32a, and the valve shaft 22 is rotated by the motor 51 of the drive unit 15. If it moves, valve plate 2
1 is a flow path 3 with the valve shaft 22 and support shaft 23 as axes.
It is possible to adjust the flow rate of the hot air flowing through the flow path 38 over a wide range.

According to the example, when the diameter of the fluid flow path (that is, the inner diameter of the support member) is 200 mm and the outer diameter of the valve plate is 198 mm (therefore, the gap is 1 mm), the flow rate when the valve plate is fully closed is Q, If the flow rate when fully open is Q ₁ , the ratio between the two is Q ₁ /Q
As shown in I in FIG. 7, the flow rate ranged from about 5% to 100%, making it possible to adjust the flow rate over a very wide range. In addition, in Figure 8, Q ₁ /Q is when the above gap is 5.2 mm, and Q 1 /Q is when the gap is 15 mm.
It shows Q ₁ /Q, and it shows a great effect on controlling the amount of air blown from the tuyere from the tuyere branch pipe mentioned above.

In addition, as mentioned above, this hot air control valve has a symmetrical structure in which the first and second heat-resistant members are divided into two from the center, and are inserted on both sides of the valve body disposed at the center of the outer cylinder to rotate the valve body. A holding member with a symmetrical structure is fitted to the outer periphery of both heat-resistant members, and a stopper is attached to the outer periphery of the holding member and welded to the inner wall of the outer cylinder to connect and fix them together. Not only is it easy to manufacture, but also the flow path can be formed accurately. Therefore, the gap between the valve plate and the inner wall of the flow path can be made as small as possible, and the range of adjustment of the flow rate of hot air can also be expanded.

Furthermore, the hot air control valve is provided with a drain discharge part 16,
Hot air or condensate that enters the chamber formed between the flange of the casing and the valve stem is discharged in a timely manner, so that the hot air does not solidify in the chamber and interfere with the rotation of the valve stem, or cause rust, etc. There is no risk of this occurring and material deterioration can be prevented.

When the hot air control valve configured as described above is applied to the blast furnace operating method of the present invention, the object can be achieved.

〔Effect of the invention〕

According to the blast furnace operating method of the present invention, deposits formed on the blast furnace wall can be removed by controlling the hot air control valve provided in the corresponding blast branch pipe at the bottom of the blast furnace wall and reducing the amount of air blown from the tuyere. This method creates a gas flow locally around the deposits formed on the wall, melts and reduces the deposits, and removes the deposits.

This has the excellent effect of equalizing the gas flow in the furnace and maintaining proper blast furnace operation.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG.
Figure 3 is an explanatory diagram showing the arrangement of the taphole of a blast furnace, Figure 3 is an explanatory diagram showing the tuyere arrangement, Figure 4 is an explanatory diagram of the installation of the hot air control valve, and Figures 5 and 6 are the hot air control used in the present invention. Front view and side view showing a partial cross section of the valve No. 7
The figure is a graph showing the relationship between the gap between the flow path and the valve plate and the flow rate, and FIG. 8 is a sectional view showing an example of a conventional butterfly valve for high temperature use. In the figure, 1: Blast furnace, 2: Furnace wall, 5: Furnace temperature sensor, 6: Tuyere, 7: Blowing tuyere branch pipe, 8: Hot air control valve, 9: Annular pipe, 10: Tapping port, 12: Calculation. Control device, 13: Valve body, 14: Casing, 1
5: Valve body drive section, 16: Drain discharge section, 21:
Valve plate, 22: Valve shaft, 23: Support shaft, 31: Outer cylinder,
34: Passage, 35, 35a: Support member, 36, 3
6a: first heat resistant member, 37, 37a: second heat resistant member, 38: channel, 42, 42a: ring-shaped support member, 43, 43a: bush, 44, 44a: ring-shaped presser, 47, 47a: Ring-shaped stopper, 61: Drain drain pipe, 62: Drain drain valve. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. When blowing high-temperature hot air from the furnace tuyeres into the furnace via the tuyere branch pipes, a hot air control valve is provided for each tuyere branch pipe, and the hot air control valve controls the air flow rate of some of the tuyere branch pipes. A method of operating a blast furnace characterized by removing deposits formed on the furnace wall in the direction of the tuyere.