Blast furnace operation method

Abstract

To propose a blast furnace operation method capable of blowing high temperature air to charged materials in a furnace from the initial stage of blowing, during blast furnace startup when blowing is resumed after a pause.SOLUTION: In a blast furnace operation method in which the operation of the blast furnace is stopped, the air is suspended, and then hot air blowing is started again and the blast furnace operation is restarted, before sending hot air into the furnace through a tuyere, a piping path from a hot air furnace to the tuyere through an annular pipe or a burner is preheated, and then hot air blowing into the furnace is started. Preferably, the preheating air blowing in the piping path is performed by first sealing the tuyere with a monolithic refractory, and then releasing the air by opening an air release valve provided at the rear end of the burner and / or the piping.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for operating a blast furnace for stopping operation, shutting down the blast furnace, and then restarting blasting. [Background technology]

[0002] A blast furnace is a facility that heats, reduces, and melts iron ore using high-temperature reducing gas generated by the reaction between high-temperature air and oxygen blown in from numerous tuyere ports arranged in the direction of the blast and coke charged from the top of the furnace together with the raw materials, and discharges the molten iron and molten slag from a tap hole installed below the tuyere. During normal operation of a blast furnace, the reaction heat inside the furnace and the heat supply from the tuyere are balanced, allowing for stable operation of the blast furnace.

[0003] Here, when the blast furnace is shut down or stopped for a long time, the heat supply to the blast furnace is stopped. On the other hand, because the heat radiation continues due to the temperature difference between the inside of the blast furnace and the atmosphere, the cooling inside the furnace progresses and some of the molten material solidifies. When the blast furnace is restarted, the solidified layer inside the furnace must be melted, and for that, the coke packed layer through which the solidified material passes must be heated. For this reason, when the blast furnace is shut down for a long time or when it is expected to be restarted, the coke ratio in the furnace is increased to shut down the furnace, and thermal compensation is performed until the injection of pulverized coal can be started after the blast. At the same time, all but one or two tuyere openings above the tap hole are blocked with refractories, etc., to limit the amount of molten iron and slag generated with the blast, and a cycle of smooth discharge of a small amount of molten material is established. After that, the adjacent tuyere is opened, and the number of open tuyere openings is gradually increased, and normal operation is restored.

[0004] As a method for restoring a blast furnace to normal operation after blasting is stopped, cited document 1 discloses that in a blast furnace in a reduced-length state where the contents of the furnace are stacked below the tuyere, the contents are heated with a burner inserted from the tuyere to maintain the temperature inside the furnace. Patent document 2 also discloses that a burner is inserted from the tap hole, oxygen or the like is blown from the burner to burn the coke between the tap hole and the tuyere to reduce the volume of the solidified material, and then new coke is charged from the top of the furnace into the area where the volume has decreased, and blasting is performed from the tuyere, thereby restoring the blast furnace to normal operation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-235437 A [Patent Document 2] Patent No. 6947345 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the methods described in Patent Document 1 and Patent Document 2, the piping path from the hot stove to the tuyere of the blast furnace body is not preheated and heated during the blast furnace shutdown, and there was a problem that the blast temperature was low when starting up operation (restarting operation) after a long shutdown. In addition, in the past, when trying to heat up a series of piping (annular pipe elbow, hot blast branch pipe, upper and lower horizontal pipes, mixed cooling pipe, burner, etc.) from the hot stove to the blast furnace body during the blast furnace shutdown, the air in the piping, which has a low temperature during the heating process, must be discharged into the furnace through the tuyere. Therefore, low-temperature molten material is generated in the furnace, which may cause problems in starting up operation (restarting operation). In other words, in the past, the temperature of the piping path during the blast furnace shutdown was not raised.

[0007] The object of the present invention is to solve the problems associated with the conventional techniques and to propose a blast furnace operation method capable of blowing high-temperature air to the contents of the furnace from the beginning of the blast blowing process when the blast furnace is started up again after the blast blowing process has been stopped. [Means for solving the problem]

[0008] The blast furnace operating method of the present invention is a method for operating a blast furnace in which operation of the blast furnace is stopped and blasting is suspended, and then hot air blowing is started again to restart the furnace, in which, prior to supplying hot air into the furnace through the tuyere, the piping path from the hot stove through the annular pipe and burner to the tuyere is preheated, and then blowing of hot air into the furnace is started.

[0009] In addition, in the blast furnace operation method of the present invention, (1) The preheating and blowing of air in the piping path is carried out by first sealing the tuyere with a moldable refractory material, and then opening the blower valve provided at the rear end of the burner and / or the piping to blow air; (2) The preheating and blowing of air in the piping path is carried out by first sealing the tuyere with a moldable refractory material and then opening the rear end of the burner to blow air. are each considered to be a preferred embodiment. Effect of the Invention

[0010] According to the blast furnace operation method of the present invention, during the blast stop, hot air is passed from the hot stove to just before the sealed tuyere and released to the outside of the furnace from a blast valve provided at the rear end of the burner and / or the piping, preferably from the rear end of the burner, thereby raising the temperature of the refractory from the hot stove to the tuyere without sending hot air into the blast furnace. As a result, when restarting operation after a long blast stop, the temperature of the blast can be raised to a hot air temperature close to that of normal operation from the beginning of the blast when hot air is blown into the furnace from the tuyere, and efficient and stable restart of the blast furnace can be realized. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram for explaining one embodiment of an apparatus for carrying out a blast furnace operation method of the present invention. [Diagram 2] 1(a) to 1(d) are schematic diagrams for explaining one embodiment of a blast furnace operating method of the present invention. [Diagram 3]1 is a graph showing an example of changes in the temperature of hot air from each tuyere in an embodiment. [Figure 4] 13 is a graph showing another example of the change in the temperature of hot air from each tuyere in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The following is a detailed description of the embodiments of the present invention. Note that the following embodiments are merely examples of devices and methods for embodying the technical ideas of the present invention, and are not intended to limit the configuration to those described below. In other words, the technical ideas of the present invention can be modified in various ways within the technical scope described in the claims.

[0013] FIG. 1 is a schematic diagram for explaining one embodiment of an apparatus for carrying out the blast furnace operation method of the present invention. In FIG. 1, 1 is a blast furnace, and 11 is a hot stove. In this embodiment, the operation of the blast furnace 1 is stopped and blasting is stopped. 2 is a furnace charge, 3 is a tuyere, 4 is a tapping hole, 5 is a burner provided in a plurality of tuyere 3, and 6 is an annular pipe for supplying hot air from the hot stove 11 to the burner 5. When blasting the blast furnace, the present invention can be applied whether or not the length is reduced, but FIG. 1 shows an example in which the level of the furnace charge 2 is reduced to just above the tuyere 3. In addition, the hot stove 11 supplies the blown air from the blower 12 as hot air through the combustion chamber 13 and the regenerator 14. The hot air supplied from the hot stove 11 is supplied to the annular pipe 6.

[0014] 2(a) to (d) are schematic diagrams for explaining an embodiment of the blast furnace operating method of the present invention. In the embodiment shown in Fig. 2(a) to (d), the tuyere 3 and the burner 5 are shown, but the other configuration is the same as the device configuration shown in Fig. 1. In the figure, 21 denotes a sight glass provided at the rear end of the burner 5.

[0015] FIG. 2(a) shows the flow of hot air during normal operation, not during cessation of blasting, and hot air from the hot stove 11 is supplied to the inside of the blast furnace 1 from the tuyere 3 through the annular tube 6 and the burner 5. In the present invention, during cessation of blasting of the blast furnace, first, as shown in FIG. 2(b), the tuyere 3 is sealed with an unshaped refractory 22 (e.g., castable). Next, as shown in FIG. 2(c), the observation window provided at the rear end of the burner 5 is opened. Next, with the observation window 21 open as shown in FIG. 2(c), hot air from the hot stove 11 is supplied to the annular tube 6 and the burner 5 as shown in FIG. 2(d). In this case, since the tuyere 3 is sealed with the unshaped refractory 22 and the observation window 21 provided at the rear end of the burner 5 is open, the supplied hot air is blown out of the furnace through the observation window 21 of the burner 5. Here, air is released from the sight glass 21 at the rear end of the burner 5, but this is not limited to this. A valve may be provided in the piping system near the blast furnace to allow air to be released, or a new piping route through which air can be released may be installed.

[0016] As described above, the present invention is characterized in that the piping path from the hot stove 11 to the tuyere 3 of the blast furnace 1, particularly the lining bricks thereof, are preheated in advance before full-scale operation is restarted. Specifically, the lining bricks in the piping path are preheated by hot air supplied from the hot stove 11, and at the same time, the air from the hot stove 11, whose temperature has been reduced due to the preheating, is not sent through the tuyere 3 into the furnace before restarting, but is instead blown from the sight hole 21 in front of the tuyere 3, preferably at the rear end of the burner 5, to prevent it from entering the furnace.

[0017] For this reason, in the present invention, the tuyere 3 is filled in advance with castable refractory material such as castable to seal the tuyere 3, thereby preventing the blast air, whose temperature has been reduced by heat exchange with the lining bricks, from entering the furnace through the tuyere 3. EXAMPLES

[0018] Internal volume 5000m 3In the blast furnace 1, the piping path from the hot stove 11 through the annular pipe 6 and the burner 5 to the tuyere 3 was preheated during the blast stop based on the steps shown in Fig. 2(a)-(d) using the apparatus configuration shown in Fig. 1. Then, when restarting operation after the blast stop, the change in the blast temperature at the #2 tuyere, the #9 tuyere, and the #10 tuyere among the multiple tuyere 3 was obtained. Fig. 3 shows the case where blasting into the blast furnace was started without preheating and without filling the tuyere 3 with unshaped refractory, and it can be seen that the temperature rose only about 50°C from 650°C even after 4 hours from the start. In contrast, Fig. 4 shows the case where the tuyere 3 was filled with unshaped refractory and preheated by blowing air from the rear end of the burner 5. By appropriately increasing the air volume, the temperature could be raised by about 200°C even in about 4 hours, and by removing the unshaped refractory filled in the tuyere 3 and restarting operation after the blast stop, it became unnecessary to blow low-temperature air into the blast furnace. [Industrial Applicability]

[0019] According to the blast furnace operation method of the present invention, a stable operation method can be provided not only for restarting a blast furnace, but also for various vertical melting furnaces other than a blast furnace. [Explanation of symbols]

[0020] 1 blast furnace 2 Furnace contents 3 Tuyere 4 Taphole 5 Burner 6 Circular pipe 11 Hot stove 12 Blower 13 Combustion chamber 14 Heat storage chamber 21 Peephole 22 Monolithic refractories

Claims

1. In a blast furnace operation method in which the operation of a blast furnace is stopped, blowing is stopped, and then hot air blowing is started again to restart the furnace, A method for operating a blast furnace in which, prior to supplying hot air into the furnace through the tuyere, the piping path from the hot stove through the annular pipe and burner to the tuyere is preheated, and then when starting to blow hot air into the furnace, the preheated air in the piping path is preheated by first sealing the tuyere with amorphous refractory material and then opening a blast valve provided at the rear end of the burner and / or the piping, or by installing a blast valve in the piping path and blasting air.

2. 2. The method for operating a blast furnace according to claim 1, wherein the preheating and blowing of air in the piping is carried out by first sealing the tuyere with a castable refractory material and then opening the rear end of the burner to blow air.

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