JP2006057175A - Method for igniting furnace top part at stopping time of blasting in blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for igniting the inner part of a blast furnace at the stopping time of blasting in the furnace by which it can be avoided to develop gas explosion and gas poisoning caused by combustible blast furnace gas containing CO, H<SB>2</SB>developed from raw material surface in the furnace and the stable ignition-state can be obtained. <P>SOLUTION: A lower stock level operation in the blast furnace is performed by setting the level of the raw material surface 10 at the furnace wall 4 side in the blast furnace near to the lower part of a tuyere 2 and also, the tuyere metallic material 3 having an air sucking hole 3A and a hot-blasting inlet 3B adjustable to sucked air amount, is used as an ignition device, and just before starting the stop of blasting, a furnace top breather valve is opened and simultaneously, the air sucking hole in the tuyere metallic material is opened at a prescribed degree, and the blast furnace gas developed from the raw material surface at the front of the tuyere, is made to be the ignition-state and the stop of the blasting in the blast furnace is started while securing the suction of the air. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an in-furnace ignition method when a blast furnace is shut down, and more specifically, when a blast furnace is shut down when combustible blast furnace gas generated from a raw material surface in the furnace is burned in the furnace. Relates to an in-furnace ignition method.

Generally, in a blast furnace, blowing to the blast furnace is stopped when repairing an incidental equipment or repairing a furnace wall in the furnace. This is called a blast furnace break. At this time, if flammable blast furnace gas containing CO and H ₂ stays in the furnace space, there is a risk of gas explosion and gas poisoning.

Therefore, for example, in Patent Document 1, a part of the rising gas pipe of the blast furnace is partially cut off when the blast furnace is shut down, a pipe having a shut-off valve is welded to the part, and an exhaust fan connected to the pipe is provided. Proposed. The blast furnace resting procedure described in Patent Document 1 is as follows.
(1) The furnace top bleeder valve and the shutoff valve are closed before the blast furnace is closed, and the amount of raw material charged from the charging chute for charging the raw material is reduced. At that time, the coke ratio during the charging of raw materials is appropriately changed according to the resting time.
(2) The amount of air blown from the tuyere and the air pressure are gradually reduced. Lower the raw material surface level in the furnace to the point where the furnace wall is repaired, and stop blowing. At this time, the raw material is not charged from the charging chute.
(3) Next, with the blowing stopped, the furnace top bleeder valve is opened, and the blast furnace gas in the furnace is diffused from the bleeder pipe.
(4) The shutoff valve is opened from the closed state and the exhaust fan is started at the same time.

  Then, the blast furnace gas in the furnace is forcibly sucked into the exhaust fan, and the atmosphere near the repair opening and the charging bell is sucked into the furnace. Therefore, a blast furnace air suspension work procedure is described in which the furnace wall can be repaired without worrying about gas explosion or gas poisoning.

  However, as described in Patent Document 1, in order to perform a blast furnace break and safely perform repair work in the furnace, a portion of the blast furnace rising gas pipe is partially cut out during the blast furnace break, There is a drawback in that the equipment must be modified such that a pipe having a shut-off valve is welded and an exhaust fan connected thereto is provided.

On the other hand, Patent Documents 2 and 3 stagnate in the space at the top of the furnace, the ignition lance, and the top of the furnace, which ignites the flammable gas generated at the blast furnace outlet when the blast furnace is closed and burns the blast furnace gas. A furnace apex burner device has been proposed that can reliably ignite combustible gases.
Japanese Patent Laid-Open No. 2-57624 Japanese Utility Model Publication No. 5-54525 JP-A-6-241453

However, Patent Documents 2 and 3 do not refer to the in-furnace ignition procedure when the blast furnace is closed, and gas explosions and gas caused by combustible gas containing CO and H ₂ generated from the raw material surface in the furnace There was a risk of poisoning.

The present invention solves such problems, can avoid the occurrence of gas explosion and gas poisoning caused by combustible gas containing CO and H ₂ generated from the raw material surface in the furnace, and creates a stable ignition state It is an object of the present invention to provide a method for in-furnace fire during blast furnace quiescence.

  The present invention relates to a method for igniting in-furnace in a blast furnace when the flammable blast furnace gas generated from the surface of the raw material in the furnace is combusted in the furnace when the blast furnace is shut down. The raw material surface level is set near the lower part of the tuyere and the blast furnace is scaled down, and a tuyere metal fitting having an air suction port and a hot air inlet capable of adjusting the amount of air to be sucked in is used as an igniter. Open the furnace top bleeder valve immediately before entering the rest of the air, and at the same time open the air inlet of the tuyere metal a predetermined amount, ignit the blast furnace gas generated from the raw material surface in front of the tuyere, ensuring air inhalation In this state, the in-furnace ignition method is performed when the blast furnace is closed.

According to the blast furnace top firing method during blast furnace rest according to the present invention, when repairing the lining of the furnace wall in the vicinity including the tuyere, CO, H ₂ generated from the raw material surface in the furnace is included. Gas explosion and gas poisoning caused by combustible gas can be avoided, and a stable ignition state can be created.

  Hereinafter, the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic diagram illustrating a furnace top-ignition method when a blast furnace according to the present invention is closed, and FIG. 2 is a schematic diagram illustrating the vicinity of tuyere 2 of a blast furnace 1 to which the present invention is applied. is there.

  The blast furnace 1 to which the present invention is applied has a furnace top charging device 5 as shown in FIG. 2, and when repairing the lining of the furnace wall 4 including the tuyere 2 in the vicinity thereof, the scale of the blast furnace is reduced. Operate and enter the blast furnace 1 break. The scale-down operation of the blast furnace 1 is normally performed by gradually reducing the amount of raw material charged from the charging chute 6 of the furnace top charging device 5 into the furnace and sending hot air supplied from the tuyere 2 to the furnace. The air volume is gradually decreased, and the raw material surface 10 in the furnace is lowered to a predetermined position.

  In FIG. 2, reference numeral 11 indicates a furnace space above the raw material surface 10, and reference numeral 7 indicates a riser pipe communicated with the furnace space 11. A furnace top bleeder valve 8 is provided between the ascending pipe 7 and the bleeder pipe 9 connected to the atmosphere. The furnace top bleeder valve 8 is opened immediately before the blast furnace 1 is closed.

  The tuyere 2 is provided with a tuyere hardware 3. As shown in FIG. 1, the tuyere metal fitting 3 has an air suction port 3A and a hot air inlet 3B that can adjust the amount of air to be sucked, and a large cover 31 and a small cover 32 are provided in the air suction port 3A. . When the large cover 31 of the tuyere hardware 3 is opened, a larger amount of air can be introduced into the furnace from the tuyere 2 than when the small cover 32 is opened. When the air inlet 3A of the tuyere hardware 3 is opened, the tuyere 2 communicates with the atmosphere.

For this reason, in the blast furnace 1 provided with the tuyere metal fitting 3 described above, the furnace top bleeder valve provided in the bleeder pipe 9 that is opened to the atmosphere at the same time that the small cover 32 of the tuyere metal fitting 3 is opened immediately before the breakage occurs. When 8 is opened, immediately before entering the resting wind, as shown in FIGS. 1 and 2, the raw material surface 10 level on the furnace wall 4 side in the furnace is lowered below the tuyere 2 by the reduced operation of the blast furnace 1. Therefore, a gas flow is generated with the furnace body as a vent as shown by an arrow in FIG. At that time, the amount of air introduced from the tuyere 2 into the furnace through the tuyere metal 3 is the complete combustion of combustible gas containing CO and H ₂ generated from the raw material surface 10 in the furnace by oxygen in the air. The amount that can be made.

  In FIG. 1, an arrow 21 indicates the flow direction of air introduced from the tuyere 2 into the furnace through the tuyere hardware 3. An arrow 22 indicates the flow direction of hot air introduced from the tuyere 2 into the furnace through the tuyere hardware 3. The hot air is stopped from blowing into the furnace when the wind is off.

  In the in-furnace ignition method of the blast furnace according to the present invention, the reduced operation of the blast furnace 1 is performed by setting the raw material surface 10 level on the furnace wall side in the furnace near the lower part of the tuyere 2, The tuyere hardware 3 is used as an in-furnace ignition device. In the furnace ignition method at that time, the furnace top bleeder valve 8 is opened immediately before the blast furnace 1 enters the resting wind, and at the same time, the small cover 32 of the air suction port 3A is opened, and the tuyere 2 is introduced into the furnace. The blast furnace gas generated from the raw material surface 10 in front of the tuyere 2 by the oxygen in the air is ignited, and the blast furnace 1 enters a quiescent state with air sucked in.

  Thereafter, the large cover 31 of the air suction port 3A is opened, and the furnace ignition work is completed.

After the blast furnace 1 enters the resting wind, the large cover 31 of the air suction port 3A is opened to complete the in-furnace ignition work. This is because the blast furnace gas containing CO and H ₂ generated from the raw material surface 10 in the furnace is completely burned while supplementing air and maintaining the ignition state.

That is, according to the present invention, the furnace top bleeder valve 8 is opened immediately before the blast furnace 1 enters the rest period, and at the same time, the small cover 32 of the air inlet 3A is opened, and oxygen in the air introduced into the furnace from the tuyere 2 is opened. Since the blast furnace gas generated from the raw material surface 10 in front of the tuyere 2 is in an ignition state and the blast furnace gas containing CO and H ₂ generated from the raw material surface 10 in the furnace is completely burned, CO gas and H ₂ gas Can be prevented from accumulating in the furnace.

Further, as shown in FIG. 1, the tuyere hardware 3 used in the present invention has an air suction port 3A and a hot air inlet 3B in which the amount of air to be sucked can be adjusted, and is generated from the raw material surface 10 in the furnace. Since an amount of oxygen that can completely burn the blast furnace gas containing CO and H ₂ can be introduced into the furnace from the tuyere 2, a stable ignition state can be created.

In addition, according to the furnace top fire operation when the blast furnace of the present invention is closed, a gas flow having a furnace body as a vent as shown by an arrow in FIG. 2 can be formed, so that CO and H ₂ are included. The gas containing CO ₂ and water vapor generated by the complete combustion of the combustible blast furnace gas and nitrogen gas in the air introduced into the furnace passes through the riser pipe 7 with the furnace top bleeder valve 8 opened, and the bleeder. Released from the tube 9 into the atmosphere.

Therefore, according to the in-furnace ignition method of the present invention when the blast furnace is closed, gas explosion or gas poisoning caused by combustible blast furnace gas containing CO and H ₂ generated from the raw material surface 10 in the furnace occurs. This makes it possible to repair the lining of the furnace wall 4 in the vicinity including the tuyere 2 in a safe state.

FIG. 3 shows the result of applying the blast furnace top firing method of the present invention when the blast furnace is closed to the blast furnace 1 having an in-furnace volume of 4300 m ³ as shown in FIG. The tuyere 2 of the blast furnace 1 is provided at a position directly above the raw material surface 10 level SL (stock line) on the furnace wall 4 side in the furnace at 24 m. The raw material surface level SL on the furnace wall 4 side in the furnace was indicated by a value measured downward from the furnace top using an appropriate detector.

Incidentally, V _B, T _B shown in FIG. 3 illustrates the blowing rate of the hot air supplied via the hot air inlet 3B of the blade cap material 3 into the furnace blast 1 and the hot air temperature, respectively. O ₂ represents the amount of oxygen in the air introduced from the tuyere 2 into the furnace. In FIG. 3, the amount of oxygen in the air shows the progress until the blast furnace is closed. Although not shown in FIG. 3, the large cover 31 of the air inlet 3A was opened when 20 minutes had elapsed after entering the blast furnace breezes, and the furnace apex operation was completed.

As a result, it is possible to avoid the occurrence of gas explosion and gas poisoning due to the flammable gas containing CO and H ₂ generated from the raw material surface 10 in the furnace, and to create a stable ignition state, which is safe. In the state, the lining of the furnace wall 4 in the vicinity including the tuyere 2 could be repaired.

It is a schematic diagram explaining the furnace top-ignition method at the time of a blast furnace resting time concerning the present invention. It is a schematic diagram of a blast furnace to which the present invention is applied. It is a graph which shows the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blast furnace 2 tuyere 3 tuyere hardware 3A air inlet 31 large cover 32 small cover 3B hot air inlet 4 furnace wall 5 furnace top charging device 6 charging chute 7 riser pipe 8 furnace top bleeder valve 9 bleeder pipe 10 Raw material surface in furnace 11 Space in furnace 21 Flow direction of air 22 Flow direction of hot air

Claims (1)

In the in-furnace ignition method at the time of blast furnace quiescence when combustible blast furnace gas generated from the raw material surface in the furnace at the time of blast furnace quiescence,
A tuyere metal fitting having an air inlet and a hot air inlet that can adjust the amount of air to be sucked while performing the reduced operation of the blast furnace by setting the raw material surface level on the furnace wall side in the furnace near the lower part of the tuyere Is used as an igniter, the furnace top bleeder valve is opened immediately before entering the blast furnace breezes, and at the same time the air inlet of the tuyere is opened, and the blast furnace gas generated from the raw material surface in front of the tuyere is ignited. An in-furnace ignition method during blast furnace quiescence, wherein the blast furnace breezes are entered while air suction is secured.

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