JP2000212614A - Control of furnace condition at stopping time of blasting in blast furnace and jig for plugging coal waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover the furnace condition in a comparatively short term at the starting time of the furnace by restraining the cooling of the furnace body during stopping the blasting to the min. limit. SOLUTION: In a method for controlling the furnace condition at the stopping time of blasting in the blast furnace, the inner pressure in the furnace near a tuyere in the blast furnace under stopping state of the blasting is measured, the difference ΔP between the inner pressure and the top pressure in the furnace is obtained and a furnace top bleeder is closed when the pressure difference ΔP in the furnace exceeds a control value, and further, a furnace top manhole is opened. A jig for plugging coal waste is provided with a shut-off disk for plugging a blasting branch tube, a hollow tube for penetrating the shut-off disk and opening at the tuyere side and a pressure gage connected with the outside end part of the hollow tube so as to measure the pressure in the surroundings of the tuyere with the pressure gage. The invasion of outer air caused by the rising of the pressure difference ΔP in the furnace is restrained and the excessive cooling of the furnace body is not developed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace condition management method and a jig for bottling, which can recover a furnace condition in a short time when air supply to a blast furnace in a calm state is resumed.

[0002]

2. Description of the Related Art In a blast furnace operation, ore and auxiliary materials are charged from the furnace top, and hot air is blown from a large number of tuyeres provided on the same circumference near the lower part of the blast furnace. The hot air burns coke in the furnace and generates a Bosch gas in which CO and N ₂ are mixed. Bosch gas heats and reduces iron ore while rising in the furnace. The iron generated by the reduction absorbs C as it descends in the blast furnace, turns into pig iron, melts, and drops downward in the furnace. Hot metal accumulated in the lower part of the furnace is tapped continuously or intermittently, and is conveyed to the next step through a tapping gutter. During regular maintenance and production adjustment, the pressure inside the furnace is gradually lowered to shut off the generated gas recovery system, close the hot air valve of the blower tube, and stop blowing hot air into the furnace. In the calm state, no heat is supplied to the furnace body, so that heat loss from the furnace body is suppressed as much as possible by adjusting the amount of cooling water and closing the tuyere.

[0003]

However, when the blast furnace is shut down for a long time, specifically for 3 hours or more, the furnace top fire is obligatory to ensure the safety of the working environment around the furnace top. . The coke at the top of the furnace burns due to the furnace top fire, and the gas flow rate flowing out of the bleeder increases. As a result, the draft inside the furnace is increased, and the invasion of outside air is promoted. If the amount of the cooling water is reduced during the calm, the cooling of the furnace body is delayed. However, simply controlling the amount of water does not provide sufficient thermal management of the furnace body. In order to prevent the furnace body from being cooled due to the intrusion of outside air, the clay is filled into the ventilation branch pipe and the tuyere is closed to close the tuyere. Exposure to water causes drying shrinkage, creating a gap between the clay and the ventilation branch. As a result, the outside air is still sucked into the furnace and cools the inside of the furnace.

[0004]

SUMMARY OF THE INVENTION The present invention has been devised in order to solve such a problem. The pressure inside the furnace is measured with a pressure gauge attached to the tuyere, and the measured value is changed to a control value. An object of the present invention is to reduce the invasion of outside air into the furnace during a pause in wind by controlling so as to be contained, and to recover the furnace condition in a short period of time after restarting the ventilation. In order to achieve the object, the furnace condition management method of the present invention measures the furnace pressure near the tuyere of a blast furnace in a calm state, determines the furnace pressure difference ΔP from the furnace top pressure, and calculates the furnace pressure difference. When ΔP exceeds the control value, close the furnace bleeder,
Further, the furnace top manhole is opened. The jig used for this furnace condition management method is a shield disk that closes the blower branch pipe, a hollow tube that penetrates the shield disk and opens to the tuyere side, and is connected to the outer end of the hollow tube. The pressure inside the furnace around the tuyere can be measured with a pressure gauge.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, for example, a blowing tuyere of a blast furnace is closed by using a jig (a) for filling as shown in FIG. 1 (b). In the jig 10 for filling, a shielding disk 12 is fixed near the tip of a hollow tube 11, and a handle 13 is provided on the hand side. The shielding disk 12 is the tuyere 2
It has a diameter slightly smaller than the inner diameter of the blower branch pipe 21 that reaches zero. A pressure gauge 16 such as a digital manometer is connected via a cock 15 to a through hole 14 extending in the longitudinal direction of the hollow tube 11. The pressure gauge 16 is connected to the recording / calculation unit 17 so that the measurement data is output to the recording / calculation unit 17. The jig 10 for stuffing is composed of the blower pipe 2
The shielding disk 12 is inserted into the blower branch pipe 21 such that the shielding disk 12 is positioned in the blower branch pipe 21 branched from the branch 2. The shielding disk 12 prevents air from being sucked in from the blower annular tube 22. In the inserted state, the handle 13 is located at the insertion port 23 of the blower branch pipe 21. When the gap between the inner surface of the ventilation branch pipe 21 and the shielding disk 12 is filled with the clay 24, the tuyere 20 is closed.

However, the filled clay 24 is exposed to a high-temperature atmosphere in the furnace, and the occurrence of shrinkage and cracks due to heating and drying is inevitable. Shrinkage, cracks and the like cause outside air to enter the furnace. For example, when the blast furnace is shut down for three hours or more, the top of the furnace is required to ensure the safety of the working environment around the furnace top. The coke at the top of the furnace is burned by the furnace top fire, and the gas velocity flowing out of the bleeder 26 increases. As a result, the draft inside the furnace is increased, the invasion of outside air is promoted, and the furnace body tends to cool.

Therefore, in the present invention, the pressure inside the furnace around the tuyere 20 is measured by a pressure gauge 16 communicating with the inside of the furnace through the through hole 14 of the hollow tube 11, and the measured value is recorded / calculated. 1
7, and the difference from the furnace top pressure is determined as the furnace pressure difference ΔP. Based on the obtained pressure difference ΔP in the furnace, the manhole 25 and the bleeder 26 (FIG. 2) at the furnace top are opened and closed to suppress the pressure difference ΔP in the furnace to a control value or less. That is, the pressure gauge 1
6 is equal to the control value (for example, 1
When it becomes larger than 5 mm water column), the manhole 25 at the top of the furnace is opened, and two of the four bleeders 26 are closed one after another. As a result, the gas temperature at the furnace top decreases due to the suction of air from the manhole 25, and the gas flow rate flowing out of the bleeder 26 decreases. Further, since gas escape from the bleeder 26 is reduced, the furnace top approaches atmospheric pressure,
The furnace pressure difference ΔP decreases, and the outside air sucked from the tuyere 20 decreases. When the pressure difference ΔP in the furnace becomes equal to or less than the control value, the bleeder 26 is closed (for example, when the opening degree is 10 degrees).
% Slightly open) and usually go into rest. As described above, when the blast furnace is in the calm state, the outside air suction from the tuyere 20 is suppressed to the minimum, and the heat loss is suppressed. Therefore, even if the blast furnace is started after a long-term outage, the furnace condition can be recovered in a relatively short period of time because the temperature inside the furnace is not excessively lowered. In addition, since the blast furnace is provided with a plurality of blower branch pipes 21, a plurality of jigs 10 are used for closing the blower tuyeres. Multiple jigs 10
Is used, the jig 10 for bottling provided with the pressure gauge 16 is arranged in at least one ventilation branch pipe 21. A jig for stuffing without the pressure gauge 16 is arranged for the other blower branch pipe 21, and the cock 15 is closed to shut out the outside air.

[0008]

EXAMPLE A blast furnace having a capacity of 1650 m ³ was shut down for periodic inspection, and a jig 10 for filling was attached to an air blowing branch pipe 21 connected to the tuyere 20. Clay 24 was filled. The clay 24 was refilled every four hours to be dried by heating in a high-temperature atmosphere in a furnace.
The furnace pressure around the tuyere of the blast furnace in a calm state was measured with a pressure gauge 16 and compared with the furnace top pressure to determine the furnace pressure difference ΔP. The pressure difference ΔP in the furnace increased as shown in FIG. When the furnace pressure difference ΔP exceeded the water column of 10 mm, when the bleeder 26 was closed, the rise of the furnace pressure difference ΔP stopped and the equilibrium was changed. The furnace pressure difference ΔP further decreased from the equilibrium state by opening the furnace top manhole 25.

On the other hand, when the bleeder 26 was continuously operated irrespective of the increase in the furnace pressure difference ΔP, the furnace pressure difference ΔP rose to nearly 20 mm water column as shown by the dotted line in FIG. The high furnace pressure difference ΔP means that outside air enters the furnace through the tuyere 20 from the gap of the clay 24 by that much. The change in the pressure difference ΔP in the furnace has a large change in the amount of air blown after the start of the stall. That is, when the in-furnace pressure difference ΔP was controlled according to the present invention, the predetermined blowing amount was reached in a short time, but when the in-furnace pressure difference ΔP was not controlled, the rising of the blowing amount was slow, and the furnace condition was recovered. It took a long time.

[0010]

As described above, in the present invention, the furnace top bleeder and the furnace top are determined based on the furnace pressure difference of the blast furnace in a calm condition so that the furnace pressure difference does not exceed the control value. The manhole is opened and closed. Thereby, invasion of outside air is suppressed to a minimum, and cooling of the furnace body is prevented, so that the furnace condition recovers in a relatively short period of time when starting up after a cold season.

[Brief description of the drawings]

FIG. 1 is a schematic view of a jig for stuffing according to the present invention (a) and a cross-sectional view of a state where the jig is inserted into a ventilation branch pipe (b).

Fig. 2 Schematic diagram of blast furnace

FIG. 3 is a graph showing the influence of the control of the furnace pressure difference ΔP on the start-up after a cold shutdown.

[Explanation of symbols]

10: Jig for stuffing 11: Hollow tube 12: Shielding disc 13: Handle 14: Through hole 15: Cock 16: Pressure gauge 1
7: Recorder / calculator 20: Tuyere 21: Blower tube 22: Hot air tube
23: Insertion port 24: Clay 25: Furnace top manhole 26: Furnace bleeder ΔP: Furnace pressure difference

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Shigeru Kotani 11-1 Showa-cho, Kure-shi, Hiroshima F-term in Nisshin Steel Co., Ltd. Kure Works 4K015 FD02 FD08

Claims (2)

[Claims] 1. The furnace pressure in the vicinity of the tuyere of a blast furnace in a calm state is measured, and the furnace pressure difference ΔP from the furnace top pressure is determined. When the furnace pressure difference ΔP exceeds a control value, the furnace top bleeder is used. Of the furnace condition when the blast furnace is shut down by closing the furnace and opening the top manhole. 2. A tuyere comprising: a shielding disk for closing a ventilation branch pipe; a hollow tube penetrating the shielding disk and opening to the tuyere side; and a pressure gauge connected to an outer end of the hollow tube. A jig for bottling in which the furnace pressure is measured by a pressure gauge.