JPH0776371B2 - Blast furnace operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a branch pipe air flow meter for each blower branch pipe connected to a tuyere,
The present invention relates to a method for operating a blast furnace in which a water or steam blowing nozzle is provided and a water or steam blowing amount control valve for controlling the amount of water or steam blowing is provided for each nozzle.

(Prior Art) In order to stabilize the operation of the blast furnace, it is necessary to make the gas distribution in the furnace in the circumferential direction of the blast furnace uniform. For that purpose, it is necessary to make the air permeability in the circumferential direction of the furnace uniform and the air flow from each tuyere uniform.

However, in general, for blowing air into the furnace of a blast furnace, cold air is sent from a blower to a hot air stove, and cold air that has been conditioned by adding steam or sprinkling water to the hot air stove from the air blower to a hot air stove 1000 to 12
It is done from each tuyere through each blast branch pipe through the hot air pipe of 00 ℃ and the hot air pipe and ring pipe.

It should be noted that the adjustment of the blast moisture content is provided with a water or steam blowing nozzle for each blast branch pipe, and a water or steam blowing amount control valve for controlling the amount of water or steam blowing is provided for each nozzle, independently for each tuyere. Those capable of controlling humidity are also known in JP-A-58-87210 and JP-A-58-87211.

As described above, in the blast furnace ventilation equipment, the annular pipe and the hot air stove are usually connected by a single hot air pipe, so even if the air permeability in the circumferential direction in the furnace is uniform, the blades close to the hot air pipe connection part The amount of air blown into the furnace differs between the mouth and the distant tuyere.

Such non-uniformity of the air flow from each tuyere on the blast furnace blast equipment is caused by changing the diameter of each tuyere and the setting of the valve opening of the branch air flow control valve provided on the blast branch pipe (Japanese Patent Publication No. 53-13325). Bulletin,
The problem can be solved by JP-A-60-114511. In addition, the annular tube of the blast furnace was divided into multiple parts, and each of the divided annular tubes was connected with a hot air tube, a hot air oven, and a blower, and an independent air blowing system was installed for each annular tube (Japanese Patent Publication No. 48-39122). Or
The blast branch pipe group is divided into multiple blast branch pipe groups along the circumferential direction of the blast furnace, this blast branch pipe group is connected to the distribution pipes provided for each blast branch pipe group, and each distribution pipe is connected to an annular pipe through a communication pipe. connection,
It can also be solved by installing a flow rate control valve in each communication pipe (Japanese Patent Publication No. 57-52923).

As long as the air permeability in the circumferential direction of the furnace is uniform, the amount of air blown from each tuyere is uniform as described above, and as proposed in JP-A-50-68908. In a blast furnace equipped with a branch airflow meter for each blast branch pipe, each branch airflow measured by each branch airflow meter indicates the air permeability in the furnace before each tuyere, and the branch pipe airflow measured by the above branch airflow meter group. The group shows air permeability in the circumferential direction in the furnace.

On the other hand, the non-uniformity of air permeability in the circumferential direction of the furnace is caused by coke, ore particle size segregation, non-uniformity of raw fuel properties, deterioration of profile due to damage to the furnace body, and the like.

(Problems to be solved by the invention) By the way, such non-uniformity of air permeability in the circumferential direction of the furnace is
It can be solved by controlling the distribution of the charge from the top of the furnace, but it takes several days to determine the effect after taking the action of the distribution of the charge. That is, the charge distribution control cannot immediately eliminate the non-uniformity of air permeability in the circumferential direction of the furnace.

The present invention is a branch air flow meter for each blow branch pipe connected to the tuyere,
A specific tuyere due to an increase in the blast moisture of the specific tuyere, which is a new finding in a blast furnace that is provided with a water or water vapor injection nozzle and a water or water vapor injection amount control valve that controls the amount of water or water vapor injection for each nozzle. (EN) A blast furnace operating method capable of rapidly maintaining uniform blast furnace operation by utilizing the immediately-improving characteristics of in-furnace air permeability to promptly make uneven the air permeability in the furnace circumferential direction. Is.

(Means for Solving Problems) The gist of the present invention is as follows.

In a blast furnace equipped with a branch pipe airflow meter, a water or steam blowing nozzle for each blower branch pipe connected to the tuyere, and a water or steam blowing amount control valve for controlling the water or steam blowing amount for each nozzle, the branch pipe air amount The air volume of the meter group is regularly detected, and the opening of the air or steam injection amount control valve of the air blow branch pipe where the air volume has decreased from the uniform set air volume of each air blow branch pipe,
Each water or steam blowing amount control valve is blown into the furnace through the nozzle, blast branch pipe, and tuyere by increasing the water flow from a uniform set opening, and is connected to the blast branch pipe whose air volume is less than the set air volume. A method for operating a blast furnace, characterized in that the air permeability in the furnace before the tuyere is improved and the opening of the water or steam injection control valve is returned to the set opening.

The inventors of the present invention carried out the water spray conditioning with the cold air tube and connected a single hot air tube to the annular tube, and provided 27 tuyere provided at equal intervals in the furnace circumferential direction as shown in FIG. A branch pipe air flow meter 3 and a steam injection nozzle 4 are provided for each of the 27 blower branch pipes 2 connected to 1, and a steam injection amount control valve 5 having the valve opening degree-flow rate characteristics shown in FIG. , Each tuyere 1
If the air permeability in the previous furnace is uniform, the amount of air blown from each tuyere 1 in a state in which steam is not blown in at a uniform opening of each steam blowing amount control valve 5, that is, in a fully closed state (opening 0%). In the blast furnace 6 in which the diameters of the tuyere 1 are adjusted so as to be uniform, the opening of one steam blowing amount control valve 5 is fully adjusted as shown in FIG. Closed (opening 0
%) To open the opening to 50% to increase the moisture content by blowing steam and measure the branch air flow rate with the branch pipe air flow meter 3 installed in the blower branch pipe 2, and the branch pipe air volume increases after the steam is blown. It has been found that the air permeability in the furnace in front of the tuyere 1 is immediately improved by doing so, that is, by increasing the amount of moisture sent from the tuyere 1.

It is not clear the mechanism by which the air permeability of the charging material in front of the tuyere 1 is immediately improved by opening the water vapor injection control valve 5 to increase the amount of moisture sent from the tuyere 1. This is because when the amount of blast moisture from the tuyere 1 increases, the water gas reaction (H ₂ O + C → H ₂ + CO) of the powder coke in the raceway is promoted, and the coke powder ratio in the raceway decreases. Conceivable.

In addition, the present inventors changed the steam to water in the blast furnace 6 and increased the blast moisture that is blown into the furnace from one tuyere by blowing water, and as a result, the tuyere that increased the blast moisture content. It was also confirmed that the air permeability in the previous furnace was immediately improved.

Incidentally, the set opening of the water or steam injection amount control valve means, for example, if a single hot air tube is connected to an annular tube and the air permeability in the circumferential direction of the furnace is uniform, the air flow from each tuyere is reduced. In a blast furnace in which the caliber of each tuyere is adjusted so that the air volume becomes uniform and the blast moisture is adjusted to a predetermined humidity by a cold air tube, for example, it is fully closed, that is, the opening is 0%.

Further, for example, in the blast furnace in which the air conditioning is controlled only by blowing water or steam from the water or steam blowing nozzles in place of the air conditioning in the cold air tube, it is necessary to set the predetermined humidity. It is the valve opening.

Further, in the above-mentioned blast furnace, which has a blower facility proposed in JP-A-48-39122 or JP-B-57-52923, the unevenness of the blown amount from each tuyere on the blower is eliminated. When the blast moisture is adjusted to the specified humidity valve with a cold air tube,
The set opening degree of the water or steam injection amount control valve is, for example, fully closed, that is, the opening degree is 0%, and the case where the air and humidity are adjusted only by blowing water or steam from each water or steam injection nozzle Is the valve opening required to achieve the above-mentioned predetermined humidity.

Further, as the set air flow rate of the blower branch pipe, for example, the total air flow rate of the blast furnace divided by the number of tuyere of the blast furnace, or a logical average air flow rate (1-α) × logical average air flow (where α <1, α is The blast furnace operation can be stably maintained by empirically determining the reduced air flow rate from the theoretical average air flow rate).

(Example) Hereinafter, the blast furnace operating method of the present invention will be described in detail based on an example.

A cold air tube was used to control the water content of the blast with a humidity of 36 (g / Nm ³ ), and a single hot air tube was connected to the annular tube. Connect with tuyere 1 of the book
A branch pipe air flow meter 3 and a steam blowing nozzle 4 are provided for each of the 27 blow branch pipes 2, and a steam blowing amount control valve 5 having the valve opening-flow rate characteristics shown in FIG. With a uniform opening of the volume control valve 5, for example, fully closed (opening 0%), the air volume from each tuyere 1 is adjusted so that the air volume from each tuyere 1 is uniform. ³ / min)
In the blast furnace 5 having a [logical average air flow rate of 150 (Nm ³ / min)], for example, the distribution of the steam injection amount control valve opening in the circumferential direction in FIGS. 4 and 6 (hereinafter abbreviated as the circumferential valve opening distribution) ), The air flow rate (Nm ³ / min) is periodically adjusted by the four groups of branch pipe anemometers while the air is blown at a uniformly set opening of each steam blowing amount control valve 5, that is, at a fully closed position (opening 0%). For example, it is detected every 20 minutes, and the branch pipe air flow distribution in the circumferential direction as shown in FIG. 5 and FIG.

In the distribution diagrams shown in FIGS. 4 to 7 and FIGS. 8 to 13, which will be described later, 1 to 27 indicate the tuyere and blast branch pipe numbers of the blast furnace 5 in the circumferential direction. In the circumferential valve opening distribution charts in Figures 4, 6, 8, 10, and 12, 0, 50, and 100 indicate the valve opening (%), and the circumferences in Figures 5, 7, 9, 11, and 13 In the directional branch airflow distribution map, 100, 150, 200 indicate the branch airflow (Nm ³ / min).

Further, in the embodiment described in detail below, the set air volume is [(1
−α) × logical average air volume], and α = 0.
03 is adopted. In addition, the air volume of each blast branch pipe is [(1 ± α)
X logical average air volume], it is judged that the circumferential branch pipe air volume is uniform and the air permeability in the furnace circumferential direction is uniform.

Now, as shown in the circumferential valve opening distribution of FIG. 4, the total steam injection amount control valve 5 is at the set opening, and the circumferential branch pipe air amount is uniform as in the circumferential branch pipe air amount distribution of FIG. Even though the air permeability in the circumferential direction was uniform, the set valve opening distribution was the same as in Fig. 4 due to disturbances such as segregation of coke and ore particles, non-uniformity of raw fuel properties, and deterioration of profile due to damage to the furnace body. (See Fig. 6) Below, like the circumferential branch pipe air flow distribution in Fig. 7.
The air volume of branch pipes 2 and tuyeres 1 of Nos. 2 to 9 decreased from the set air volume, and non-uniformity of circumferential branch pipe air volume was detected as shown in Fig. 7, and air permeability in the circumferential direction of the furnace was non-uniform. Is detected, N
o.2-9, the valve opening of the steam injection amount control valve 5 of the steam injection nozzle 4 of the blower branch pipe 2 is increased from the set opening as shown in FIG. Increase the blast moisture above 1. No. 2 to 9 blower branch pipes 2 and tuyere 1 are operated by increasing the opening degree of the steam blown amount control valve 5 of the steam blow nozzle 4 of the No. 2 to 9 blower branch pipes 2. Due to the increase in the amount of blast moisture in the furnace, the in-furnace air permeability in front of tuyere 1 of Nos. 2 to 9 was improved, and from Fig. 9 to Fig. 9 under the same valve opening distribution as Fig. 8 (see Fig. 10). No.2 ~ 9 as shown in Fig. 11
The air volume of the blast branch pipe 2 and the tuyere 1 recovers toward the uniform set air volume and the theoretical average air volume of 150 (Nm ³ / min) of each blast branch pipe 2 in this way. No.2 due to increase in the amount of moisture blown in the furnace from No.2-9 blower branch pipes 2 and tuyere 1 by the operation of increasing the valve opening of the steam injection amount control valve 5 of the steam injection nozzle 4 No.2 to 9 blows as shown in Fig. 9 to Fig. 11 under the same valve opening distribution as Fig. 8 (see Fig. 10) with improved air permeability in front of tuyere 1 The air volume of branch pipe 2 and tuyere 1 is set air volume and logical average air volume of 150
When recovering toward (Nm ³ / min), No. 2 as shown in Fig. 12
~ 9 of the steam blowing nozzle 4 of the blow-off branch pipe 2 to return the valve opening of the steam blowing amount control valve 5 to the set opening, that is, fully closed, and then detect the branch pipe air volume (Nm ³ / min) with the branch pipe air flow meter 3 group Then, the distribution flow amount of the branch pipe in the circumferential direction is detected. Based on this branch pipe airflow distribution, the uniformity of the air permeability in the circumferential direction of the furnace is judged, and the uniformity of the circumferential branch pipe airflow is ensured as in the circumferential branch pipe airflow distribution of Fig. 13. Until it is judged that the air permeability in the direction is uniform, the operation of increasing the valve opening of the steam blowing amount control valve 5 of the steam blowing nozzle 4 of the blower branch pipe 2 of the set air volume or less to the set opening or to the set opening Repeat the return operation.

If the uniformity of the circumferential branch pipe airflow is ensured as shown in the circumferential branch pipe airflow distribution in Fig. 13 and the air permeability in the circumferential direction of the furnace is also ensured, the total amount of steam injected is as shown in Fig. 12. Air is blown with the valve opening of the control valve 5 kept at the set opening (fully closed),
The tributary air flow meter (group ³ ) regularly detects the tributary air flow (Nm ³ / min) to detect the tributary air flow distribution in the circumferential direction.

Next, the specific implementation results will be described. When the opening of the total steam injection amount control valve 5 is below the set opening (fully closed = 0% opening), the branch pipe air flow rate of the three groups of branch pipe anemometers (Nm ³ / min ) Is detected every 20 minutes to detect the distribution flow amount of the branch pipe in the circumferential direction, and the distribution flow amount of the branch pipe in the circumferential direction is uniform as shown in FIG. 5 and the air permeability in the circumferential direction of the furnace is uniform. Is detected as shown in FIG. 7, it is operated to increase the valve opening of the total steam injection amount control valves 5 of Nos. 2 to 9 as shown in FIG. After the valve opening increase operation, air is continuously blown with the valve opening distribution shown in Figs. 8 and 10. After the branch pipe air volume distribution shown in Fig. 9, 5 hours after the valve opening increase operation, the branch pipe air volume distribution shown in Fig. 11 is obtained. When it becomes
As shown in Fig. 12, when the valve opening of No. 2 to 9 steam injection control valve 5 was returned to the set opening, the branch pipe air flow distribution in the circumferential direction was made uniform as shown in Fig. 13, and The air permeability in the circumferential direction could be made uniform. That is, after the non-uniformity of the air permeability in the circumferential direction in the furnace was detected, the air permeability in the circumferential direction in the furnace could be made uniform immediately in a short time of 5 hours.

(Effects of the Invention) As described in detail above, according to the blast furnace operating method of the present invention,
The non-uniformity in the circumferential direction in the furnace can be promptly made uniform and the blast furnace operation can be stably maintained.

[Brief description of drawings]

FIGS. 1 to 3 (a) and (b) are explanatory views of the effect of immediately improving the air permeability in the furnace in front of the tuyere by increasing the blast moisture which is the basis of the method of the present invention, and FIGS. 4 to 13 show the present invention. It is explanatory drawing of one Example of the blast furnace operating method of this. 1 …… Tuyere 2 …… Blast branch pipe 3 …… Branch pipe air flow meter 4 …… Steam injection nozzle 5 …… Steam injection control valve 6 …… Blast furnace

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-51-24515 (JP, A) JP-A-58-58205 (JP, A) JP-A-58-133308 (JP, A) JP-A-54- 110906 (JP, A)

Claims (1)

[Claims] 1. A blast furnace in which a branch pipe air flow meter, a water or steam blowing nozzle is provided for each blower branch pipe connected to a tuyere, and a water or steam blowing amount control valve for controlling the amount of water or steam blowing is provided for each nozzle. In, the air flow rate of the branch pipe air flow meter group is detected periodically, and the opening of the water or water vapor injection amount control valve of the air flow tributary pipe in which the air flow amount is reduced from the uniform air flow amount of each air blow tributary pipe is controlled by each water or water vapor injection amount. In the furnace in front of the tuyere connected to the blast tributary whose air volume has decreased below the set air volume, by blowing water or steam into the furnace through the nozzle, blast tributary, and tuyere to increase beyond the uniform set opening. A method for operating a blast furnace, characterized by improving breathability and returning the opening of the water or steam injection control valve to the set opening.