JP2009235437A - Method for controlling blast furnace operation at blowing-stop time in large reduction of charged material level - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling a blast furnace operation which the lowering of the temperature in the blast furnace at blowing-stop time is prevented and the development of furnace cooling even in the blowing-stop for long time can be prevented. <P>SOLUTION: In the blast furnace, in which the blowing is stopped under state of the reducing level by laying the charged material 3 in the furnace at the lower part of a tuyere 4, the method for controlling the blast furnace operation at the blowing-stop time in the large reduction of the charged material level, is used, in which the temperature in the furnace is kept by heating the charged material 3 in the furnace with a burner 8 inserted from the tuyere 4. The temperature of the charged material 3 in the furnace, is monitored by measuring the temperature in a molten pig iron tapping hole 5, and it is desirable that the heating of the charged material in the furnace is performed with the burner 8 according to the temperature of the charged material 3 in the furnace. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an operation method when the blast furnace is scaled down for the purpose of a pause for blast furnace repair of the blast furnace, and more particularly to a blast furnace operation management method during a large scale reduced pause.

  In recent years, the lifespan of blast furnaces has greatly increased due to advances in equipment technology and operation technology, and many large blast furnaces have been operating for more than 10 years. On the other hand, the lining thickness of the lower part of the shaft and the morning glory part decreases with the passage of years of operation. Therefore, it is necessary to repair the inner surface of the shaft part and morning glory part. In that case, if there is high-temperature raw material in this part, it cannot be repaired, so the raw material charging level in the blast furnace is lowered to a predetermined height, and then the blast furnace The wind is suspended to temporarily stop operations. When the operation of the blast furnace is resumed after the repair in the furnace, the raw material is filled again and the blast furnace is started up. Thus, when performing intermediate repair of the furnace body, the operation mode in which the raw material charging level in the blast furnace is lowered is referred to as reduced scale operation. The basic method of scale-down operation is to stop the charging of iron raw material from the top of the furnace, replace it with coke, and lower the raw material charging level while burning the coke by high-temperature air supplied from the tuyere. To do. A reduction in which the raw material charging level is lowered to the tuyere level, for example, the raw material charging level is lowered by 20 m or more is called a large reduction.

  In FIG. 1, the longitudinal cross-sectional schematic diagram in the large reduced-scale resting state of a blast furnace is shown. In the figure, 1 is the top of the furnace, 2 is the rotating chute, 3 is the interior of the furnace in a large scale state, 4 is the tuyere, 5 is the spout, 6 is watering, and 7 is generated in the furnace by the watering. A watering pipe for cooling the gas.

  The reduced operation of the blast furnace is performed as follows, for example.

  First, the coke is increased and then the iron material charging is stopped. On the other hand, the raw material charging level is lowered from the tuyere 4 while hot air is blown into the furnace. This hot air flow rate is reduced according to the descending situation of the raw material. When the iron raw material charging is stopped and the hot air flow rate is reduced, the scale is reduced, and the temperature of the furnace top gas rises due to the combustion of coke and the passage of gas in the furnace. On the other hand, in order to suppress the rise in the furnace top gas temperature, the water 6 is discharged from the water pipe 7 provided at the top of the furnace to cool the gas. Even in the process of lowering the raw material charging level, the iron raw material such as iron ore must be operated so that the required preliminary reduction is performed and the hot metal generation reaction is performed while preventing the furnace cooling. Therefore, even if the iron raw material charging is stopped, the coke charging is continued to prevent the occurrence of furnace cooling.

  In this way, when the raw material charging level is reduced to a predetermined level, that is, when the scale is greatly reduced, it is lowered to the tuyere level and then the resting wind is entered. In order to prevent cold air from being sucked from the tuyere and to prevent the furnace temperature from dropping, the tuyere is closed by filling the tuyere or blowpipe with a padding such as clay or amorphous refractory. Let

A method for performing such a blast furnace scale-down operation in a short time and a method for preventing slip and blow-through are known (for example, see Patent Documents 1 to 3).
JP-A-2-282408 Japanese Patent Application Laid-Open No. 55-110710 JP-A-57-143406

  In order to resume the operation of the blast furnace as soon as possible, it is important to prevent the occurrence of furnace cooling when the wind is off. In the blast furnace at the time of a large scale downtime, there is a small amount of high-temperature furnace interior, and the heat source in the furnace is only sensible heat of hot metal. Therefore, there is a possibility that the hot metal temperature may become difficult to maintain as the wind rest time becomes longer. In addition, as described above, water spraying is performed to suppress the furnace top gas temperature, so water may be applied to the furnace interior and the temperature may be further lowered. There are also concerns about the occurrence of cooling water leaks associated with repair work.

  The temperature of the furnace interior can be confirmed, for example, by observing the red heat state of the coke at the tuyere. However, it takes time and effort to remove the stuffed material, observe the inside of the furnace, and refill the stuffed material to close the tuyere. Another problem is that air flows into the furnace every time the furnace is inspected. When air flows into the furnace, toxic gas (CO) may be generated, and the tuyere is preferably closed from the viewpoint of safety measures.

  Such a problem relating to a decrease in the furnace temperature in the blast furnace at the time of large scale downtime cannot be handled by the techniques described in Patent Documents 1 to 3.

  Therefore, the object of the present invention is to solve such problems of the prior art, to prevent a decrease in the furnace temperature in the blast furnace at the time of a large-scale reduced pause, and to prevent the occurrence of furnace cooling even during a long pause. The purpose is to provide an operation management method at the time of large scale downtime.

The features of the present invention for solving such problems are as follows.
(1) In a blast furnace resting in a reduced scale where the furnace interior is stacked below the tuyere, the furnace interior is heated by a burner inserted from the tuyere to maintain the furnace temperature. Blast furnace operation management method at the time of a large scale downtime.
(2) The temperature of the furnace interior is monitored by measuring the temperature in the tap, and the furnace interior is heated by a burner according to the temperature of the furnace interior. The blast furnace operation management method at the time of a large scale downtime as described in (1).

  ADVANTAGE OF THE INVENTION According to this invention, the furnace temperature fall in a blast furnace at the time of a large-scale reduced pause can be prevented, and generation | occurrence | production of furnace cooling can be prevented. As a result, there is no need to shorten the resting time more than necessary because of fear of furnace cooling, and repair work can be performed sufficiently.

  The present invention will be described with reference to FIG.

  In the blast furnace at the time of the large-scale reduced wind, in the present invention, the burner 8 is inserted from the tuyere 4 and the furnace interior charge 3 is heated by the burner. That is, the coke in the furnace is heated and burned by inserting the burner 8 from the tuyere 4 to maintain the temperature in the furnace. Burner heating from the tuyere can be carried out in all tuyere, but the number of tuyere to be heated can be appropriately set according to the situation at rest. When heating is not performed at all tuyere, it is preferable to arrange the tuyere to be heated at equal intervals on the circumference in the vertical cross section of the furnace, for example, every 1 to 4 tuyere It can be carried out. As the burner, a normal gas burner using fuel gas and combustion air may be used. As the fuel gas, for example, coke oven gas (C gas) can be used. The combustion air blowing pipe can be inserted into the tuyere as a pipe separate from the burner, or combustion air can be blown from the burner together with the fuel gas.

  As a result, the temperature of the furnace interior does not decrease, and the occurrence of furnace cooling can be prevented even during long periods of off-air. In this way, the operation of the blast furnace at the time of a large-scale reduced pause can be managed by heating the furnace interior with a burner inserted from the tuyere and maintaining the furnace temperature.

  When heating the furnace interior with a burner in a blast furnace during a large-scale reduced wind, it is preferable to monitor the temperature of the furnace interior. If the temperature of the furnace interior entry can be monitored, it is possible to predict that the temperature of the furnace interior entry will decrease, and to heat the furnace interior entry with a burner at an appropriate timing. Since it is difficult to directly measure the temperature in the furnace, it is preferable to measure the temperature in the tap. For example, by inserting a long rod-shaped temperature measuring instrument into the tap outlet and measuring the temperature 2 to 3 m inside the tap outlet, the temperature inside the furnace interior may be monitored to detect a temperature change. . It is possible to control the temperature in the furnace within an appropriate range by performing burner heating when the temperature inside the furnace interior falls below the specified value and stopping the burner heating when the temperature rises above the specified value. It becomes.

  Hereinafter, an embodiment of the present invention will be specifically described with reference to FIG.

  In order to perform a large scale reduction operation of the blast furnace, first, the coke is increased and charging is stopped. The raw material charging level is lowered while hot air is blown from the tuyere 4 into the furnace. The hot air blowing flow rate from the tuyere 4 is reduced according to the descending state of the raw material. When the iron material charging is stopped and the hot air flow rate is reduced, the scale is reduced. The rise in the temperature of the furnace top gas is lowered by cooling with the water spray 6 from the water spray pipe 7 provided at the furnace top. The raw material charging level is lowered to the tuyere level, the sprinkling 6 is stopped, the hot air blowing from the tuyere 4 is stopped, and the resting wind is entered. A burner 8 is inserted into the tuyere 4, and the tuyere where the burner is not inserted is filled with fillings to close the tuyere.

  A temperature measuring instrument is inserted from the tap 5 and the temperature in the furnace is monitored. When the temperature falls below a predetermined value, the surface of the furnace interior charge 3 is heated by a burner inserted in the tuyere to prevent the temperature from decreasing. As a result, it is possible to finish the resting without restarting the furnace and restart the operation. Thus, by maintaining the furnace temperature by directly heating the furnace interior, it is possible to manage the blast furnace operation at the time of large scale downtime in an appropriate state.

  The temperature measuring instrument may be a rod-shaped member that can be inserted into the tap hole, and the temperature can be measured with a built-in thermometer provided at a predetermined distance from the distal end portion and the distal end of the rod-shaped member. Thereby, the temperature in the radial direction of the furnace is measured, the temperature condition of the furnace interior is determined from the temperature change monitored in the furnace, and whether or not the burner can be inserted is determined.

Large scale reduction operation of the blast furnace was performed, the charge level in the blast furnace was set below the tuyere, watering from the top of the furnace was stopped, and blowing from the tuyere was stopped. Thereafter, repair in the furnace was started, and a burner that ignited the tuyere was inserted to heat the coke in the furnace. Burner heating was performed from eight tuyere at equal intervals in the circumferential direction. C gas (coke oven gas: main components H ₂ and CH ₄ ) was used as the fuel gas for the burner. The tuyere where the burner was not inserted was closed by filling with an irregular refractory.

  The coke was heated with a burner, and the furnace interior charge temperature was maintained. After the repair work was completed, the burner was removed from the tuyere, air blowing was started, and the operation was resumed.

  A large-scale operation of the blast furnace was performed, the charge level in the blast furnace was set below the tuyere, the tuyere was closed, and the wind was resting.

  After the rest, the temperature in the furnace was measured from the tap using a 2.5 m long rod with three temperature sensors attached every 30 cm from the tip.

Since it was found by the temperature sensor that the temperature in the furnace was declining, when the worker observed the surface of the charge, it was confirmed that the surface temperature had dropped. Inserted and heated coke. Burner heating was performed from eight tuyere at equal intervals in the circumferential direction. C gas (coke oven gas: main components H ₂ and CH ₄ ) was used as the fuel gas for the burner. The coke was heated with a burner, and the furnace interior charge temperature was maintained.

  Since the temperature measured by the temperature sensor returned to the state before the furnace temperature decreased, the burner heating was stopped at that time.

The longitudinal cross-sectional schematic diagram in the large-scale reduced-air rest state of a blast furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace top 2 Rotating chute 3 Furnace interior entry 4 Feathers 5 Outlet 6 Sprinkling 7 Sprinkling pipe 8 Burner

Claims (2)

  In a blast furnace that is rested in a reduced scale where the furnace interior is stacked below the tuyere, the furnace interior is heated with a burner inserted from the tuyere to maintain the furnace temperature. Blast furnace operation management method at the time of a large scale downtime.   The temperature of the furnace interior is monitored by measuring the temperature in the outlet, and the furnace interior is heated by a burner according to the temperature of the furnace interior. The blast furnace operation management method at the time of large scale downtime described in 1.

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