Blow-in Method for Long-Term Cooldown in Hydrogen-Enriched Carbon-Circulating Oxygen Blast Furnace

Abstract

The present invention relates to a method for ventilating a hydrogen-enriched and carbon-circulating oxygen blast furnace during a long period of ventilating shutdown. Before ventilating shutdown, the ventilating mode is switched from a mixed gas ventilating mode of hot coal gas, cold oxygen gas, and high-stability nitrogen gas to a mixed gas ventilating mode of hot compressed air, hot oxygen gas, and hot nitrogen gas. In the mixed gas ventilating mode of hot compressed air, hot oxygen gas, and hot nitrogen gas, after at least one smelting cycle has been operated, ventilating is stopped. At the beginning of re-ventilation, half of the tuyeres are opened and the other half are closed. During the re-ventilation process, the mixed gas ventilating mode of hot compressed air, hot oxygen gas, and hot nitrogen gas is used as the ventilating mode. When the tapping rate and stock line operation are normal and the number of open tuyeres accounts for 80% or more of the total number of tuyeres, the ventilating mode is switched from a mixed gas ventilating mode of hot compressed air, hot oxygen gas, and hot nitrogen gas to a mixed gas ventilating mode of hot coal gas, cold oxygen gas, and high-stability nitrogen gas. This method solves the problems that after a long period of cessation of blowing in a hydrogen-enriched and carbon-circulating oxygen blast furnace, the dead area at the tuyere is difficult to restore, the restoration speed is slow, the restoration process is likely to be repeated, and the blower at the tuyere is likely to be burned out, which makes it easy for furnace cooling accidents to occur.

Description

[Technical Field]

[0001] The present invention relates to the technical field of blast furnace steelmaking, and more particularly to a method of blowing air during long-term blast shutdown in a hydrogen-enriched, carbon-circulating oxygen blast furnace. [Background technology]

[0002] In the case of a hydrogen-enriched, carbon-recycled oxygen blast furnace, when the furnace is shut down for a long time and then re-blows, or when abnormal conditions such as the furnace body freezing or a furnace cooling accident occur, the general operation method for re-blow or to deal with abnormal conditions is to blow in highly stable nitrogen gas, then blow in cold oxygen gas and ignite it, then pass the mixed injection coal gas, increase the injection rate of the mixed injection coal gas, and decrease the amount of nitrogen gas. However, in this process, the oxygen content in the injection rate is too high, making the furnace body inert, the swirl area at the tuyere is short, the metallization rate is high when coal gas is injected with all oxygen, and the tuyere blower is easily burned and damaged. Therefore, when the furnace condition is restored with this method, the furnace condition is likely to deteriorate further, and even during the process of furnace condition restoration, repeated shutdown and blast are likely to occur. Summary of the Invention

[0003] The present invention aims to provide a method for ventilating a hydrogen-enriched, carbon-circulating oxygen blast furnace after a long period of ventilating shutdown. This method can effectively solve the problem that when a general ventilating method is used to restore the furnace condition of a hydrogen-enriched, carbon-circulating oxygen blast furnace, the furnace condition tends to deteriorate and repeated ventilating shutdowns and ventilating are likely to occur even during the process of restoring the furnace condition.

[0004] A method for blowing air during a long-term shutdown in a hydrogen-enriched, carbon-circulating oxygen blast furnace, comprising: When switching the blast mode before a long-term blast stop or when the furnace is in an abnormal state in a hydrogen-enriched, carbon-circulating oxygen blast furnace, The normal operation state of the hydrogen-enriched carbon-circulation oxygen blast furnace is in a mode of blowing a mixture of hot coal gas, cold oxygen gas, and high-stability nitrogen gas. At least one smelting cycle before the smelting stop, the blowing of hot coal gas and cold oxygen gas is stopped. Before the blowing of hot coal gas is stopped, the theoretical combustion temperature is controlled to be in the range of 1900-2400°C, and a pressure reduction operation is performed by reducing the blowing amount of coal gas and the blowing amount of oxygen gas. After the blowing of hot coal gas is stopped, the oxygen gas content in the overall blowing amount is controlled to be 25% or less until the blowing of oxygen gas is stopped. In step S1, specifically, high-stability nitrogen gas is passed through, and the high-stability nitrogen gas line control valve 44 is opened, and the high-stability nitrogen gas cutoff valves 22 and 23 are opened to control the flow rate of high-stability nitrogen gas to 5000m3 / h. Stop the injection of hot coal gas by adjusting the mixed coal gas pipeline control valve 43, reducing the amount of mixed coal gas injected until the opening of the control valve becomes 0, closing the mixed coal gas pipeline cutoff valve 27, opening the mixed coal gas pipeline nitrogen gas blow-off valve 30, blowing for 1 minute, then closing the mixed coal gas pipeline cutoff valve 28, opening the mixed coal gas pipeline release valve 32 and the mixed coal gas pipeline release valve 33, closing the mixed coal gas pipeline nitrogen gas blow-off valve 30, and closing the mixed coal gas pipeline blind valve 31; Stopping the injection of cold oxygen gas 39; Injecting hot compressed air, confirming that the compressed air line cutoff valve 2 and the compressed air line cutoff valve 3 are closed, opening the compressed air line blind valve 4, closing the compressed air line release valve 5 and the compressed air line release valve 6, opening the compressed air line cutoff valve 2 and the compressed air line cutoff valve 3, and adjusting and controlling the flow rate of the compressed air by the compressed air line adjustment valve 41; Injecting hot oxygen gas, confirming that the hot oxygen gas pipeline cutoff valve 12 and the hot oxygen gas pipeline cutoff valve 13 are closed, opening the hot oxygen gas pipeline blind valve 14, closing the hot oxygen gas pipeline release valve 15 and the hot oxygen gas pipeline release valve 16, opening the hot oxygen gas pipeline cutoff valve 12 and the hot oxygen gas pipeline cutoff valve 13, and adjusting and controlling the flow rate of the hot oxygen gas by the hot oxygen gas pipeline control valve 42; Step S1: adjusting blast parameters, including adjusting the flow rates of compressed air, hot oxygen gas, and nitrogen gas to desired values, and controlling the oxygen gas content in the overall blast volume of the mixed gas to be within the range of 21-25% during this period; in this blast mode, after at least one smelting cycle has elapsed, the blast furnace is in a blast stop state; A step S2 of re-blowing, When re-ventilating after a long period of shutdown or shutdown due to abnormal furnace conditions, before re-ventilating, ensure that half of the tuyere near the pig-hole is open and the other half away from the pig-hole is closed, and then re-ventilate half of the tuyere. During the re-ventilation process, the ventilating mode of hot compressed air, hot oxygen gas, and hot nitrogen gas mixture is still selected, that is, high-stability nitrogen gas is blown and the system is blown for 1 minute. In accordance with the procedure of blowing hot compressed air and blowing hot oxygen gas in step S1, the operation is performed by adjusting the ventilating parameters, and the oxygen gas content in the overall ventilating volume during the re-ventilation process is controlled to be within the range of 21-25%. After re-ventilation, the furnace conditions are restored using this ventilating method in step S2. When switching the ventilation mode after the furnace condition is restored, When the furnace conditions are gradually restored, the furnace temperature is normal, the iron tapping at the furnace front is normal, the charge charging is normal, and the number of open tuyeres accounts for 80% or more of the total number of tuyeres, the operation is switched from the mixed gas blowing mode of hot compressed air, hot oxygen gas, and hot nitrogen gas to the mixed gas blowing mode of hot coal gas, hot oxygen gas, and highly stable nitrogen gas (S3), specifically, the blowing of hot oxygen gas is stopped by opening the hot oxygen gas line nitrogen gas blowing valve 18 and adjusting the hot oxygen gas line control valve 42 to reduce the blowing amount of hot oxygen gas until the flow rate of hot oxygen gas becomes 0, closing the hot oxygen gas line cutoff valve 12 and the hot oxygen gas line cutoff valve 13, opening the hot oxygen gas line release valve 15 and the hot oxygen gas line release valve 16, closing the hot oxygen gas line nitrogen gas blowing valve 18, and closing the hot oxygen gas line blind valve 14; Stopping the blowing of hot compressed air, after stopping the blowing of hot oxygen gas, opening the compressed air line nitrogen gas blowing valve 8, adjusting the compressed air line control valve 41 to reduce the blowing amount of compressed air until the flow rate of compressed air becomes 0, closing the compressed air line cutoff valve 2 and the compressed air line cutoff valve 3, opening the compressed air line release valve 5 and the compressed air line release valve 6, closing the compressed air line nitrogen gas blowing valve 8, and closing the compressed air line blind valve 4; Injecting cold oxygen gas, sending cold oxygen gas 39 through the tuyere of the blast furnace, adjusting the injection amount of cold oxygen gas, controlling the oxygen gas content in the overall blast volume of the mixed gas to be within the range of 21-25% during that period, and confirming that the blast furnace is operating normally when the injection amount of cold oxygen gas reaches its maximum under the condition that the oxygen gas content in the overall blast volume is controlled to be within the range of 21-25%; and a step S3 of injecting hot coal gas, the step including confirming that the mixed coal gas pipeline cutoff valves 27 and 28 are closed, opening the mixed coal gas pipeline blind valve 31, opening the mixed coal gas pipeline nitrogen gas blow-off valve 30, closing the mixed coal gas pipeline vent valves 32 and 33, opening the mixed coal gas pipeline cutoff valves 27 and 28, and adjusting the mixed coal gas pipeline control valve 43 to gradually increase the mixed coal gas injection rate until the operation and production requirements are met, and closing the mixed coal gas pipeline nitrogen gas blow-off valve 30 after the mixed coal gas injection rate exceeds 5000 m3 / h. Because the hydrogen-enriched, carbon-recycled oxygen blast furnace has a much weaker heat storage capacity than a conventional blast furnace, this invention switches to a blast mode using a mixture of hot compressed air, hot oxygen gas, and hot nitrogen gas from the cycle immediately preceding the blast shutdown to deal with abnormal furnace conditions such as long-term shutdown, freezing of the furnace can, or furnace cooling accidents. This mode is similar to the blast mode used in conventional blast furnace smelting, significantly reducing indirect reduction reactions in the furnace and lowering the charge metallization rate. Furthermore, by supplementing coke instead of coal gas injection, the coke bed area in the can can be expanded, improving the permeability of the blast furnace. Furthermore, after re-blasting, the blast furnace can easily achieve good permeability, thereby increasing the activity of the can. During re-blasting, the tuyere is half open and half blocked, reducing the inertness of the can, thereby reducing the risk of tuyere blower burnout and water leakage. Furthermore, a blast mode using a mixture of hot compressed air, hot oxygen gas, and hot nitrogen gas can be selected as the blast mode during re-blow to better control the oxygen content and smelting intensity in the total amount of local blowing in the furnace can. As the activity of the furnace can and the permeability of the hydrogen-enriched, carbon-circulating oxygen blast furnace gradually improve, the blocked tuyeres are gradually opened. When the number of open tuyeres reaches 80% or more, the blast furnace is deemed to have met the requirements for switching to the general smelting mode of the hydrogen-enriched, carbon-circulating oxygen blast furnace, and in this case, the blast mode can be switched again. Compared with the general blast mode of the conventional hydrogen-enriched, carbon-circulating oxygen blast furnace, the method of the present invention is superior in terms of restoring furnace conditions in the hydrogen-enriched, carbon-circulating oxygen blast furnace. [Brief explanation of the drawings]

[0005] [Figure 1] 3 is a flowchart of the air blowing mode switching system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0006] The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to Figure 1. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without any creative efforts are within the scope of protection of the present invention.

[0007] As shown in Figure 1, in the method for blowing air during long-term cooling in a hydrogen-enriched carbon-circulation oxygen blast furnace according to the present invention, the blowing mode switching system includes a compressed air supply pipeline 1, a compressed air supply pipeline cutoff valve 2, a compressed air supply pipeline cutoff valve 3, a compressed air supply pipeline blind valve 4, a compressed air supply pipeline vent valve 5, a compressed air supply pipeline vent valve 6, a compressed air supply pipeline nitrogen gas blowing pipeline 7, a compressed air supply pipeline nitrogen gas blowing valve 8, a compressed air supply pipeline pressure gauge 9, a compressed air supply pipeline flowmeter 10, a hot oxygen supply pipeline 11, a hot oxygen supply pipeline cutoff valve 12, a hot oxygen supply pipeline cutoff valve 13, a hot oxygen supply pipeline blind valve 14, a hot oxygen supply pipeline vent valve 15, a hot oxygen supply pipeline vent valve 16, a hot oxygen supply pipeline nitrogen gas blowing pipeline 17, a hot oxygen supply pipeline nitrogen gas blowing valve 18, a hot oxygen supply pipeline pressure gauge 19, a hot oxygen supply pipeline flowmeter 20, a hot oxygen supply pipeline pressure gauge 21, a hot oxygen supply pipeline flowmeter 22, a hot oxygen supply pipeline pressure gauge 23, a hot oxygen supply pipeline pressure gauge 24, a hot oxygen supply pipeline pressure gauge 25, a hot oxygen supply pipeline pressure gauge 26, a hot oxygen supply pipeline pressure gauge 27, a hot oxygen supply pipeline pressure gauge 28, a hot oxygen supply pipeline pressure gauge 29, a hot oxygen supply pipeline pressure gauge 30, a hot oxygen supply pipeline pressure gauge 31, a hot oxygen supply pipeline pressure gauge 32, a hot oxygen supply pipeline pressure gauge 33, a hot oxygen supply pipeline pressure gauge 34, a hot oxygen supply pipeline pressure gauge 35, a hot oxygen supply pipeline pressure gauge 36, a hot oxygen supply pipeline pressure gauge 37, a hot oxygen supply pipeline pressure gauge 38, a hot oxygen supply pipeline pressure gauge 39, a hot oxygen supply pipeline pressure gauge 40, a hot oxygen supply pipeline pressure gauge 41, a hot oxygen supply pipeline pressure Pipeline 21, high-stability nitrogen gas cutoff valve 22, high-stability nitrogen gas cutoff valve 23, high-stability nitrogen gas pipeline pressure gauge 24, high-stability nitrogen gas flow meter 25, mixed coal gas pipeline 26, mixed coal gas pipeline cutoff valve 27, mixed coal gas pipeline cutoff valve 28, mixed coal gas pipeline nitrogen gas blowoff pipeline 29, mixed coal gas pipeline nitrogen gas blowoff cutoff valve 30, mixed coal gas pipeline blind plate valve 31, mixed coal gas pipeline diffusion valve 32, mixed coal gas pipeline release valve 33, mixed coal gas pipeline pressure gauge 34, mixed coal gas pipeline flow meter 35, general mixed gas pipeline 36, general mixed gas pipeline coal gas analyzer 37, coal gas heating furnace 38, cold oxygen pipeline 39, hydrogen-enriched carbon-circulating oxygen blast furnace 40, compressed air pipeline control valve 41, hot oxygen gas pipeline control valve 42, mixed coal gas pipeline control valve 43, and high-stability nitrogen gas pipeline control valve 44.

[0008] The compressed air line cutoff valve 2 is located at the start end of the compressed air supply pipeline 1, the compressed air line blind valve 4 is located in the compressed air supply pipeline 1 and at a position behind the compressed air line cutoff valve 2, the compressed air line cutoff valve 3 is located in the compressed air supply pipeline 1 and at a position behind the compressed air line blind valve 4, the compressed air line release valve 5 is located in the compressed air supply pipeline 1 and is located between the compressed air line cutoff valve 2 and the compressed air line blind valve 4, the compressed air line release valve 6 is located in the compressed air supply pipeline 1 and is located between the compressed air line blind valve 4 and the compressed air line cutoff valve 3, and a compressed air line pressure gauge 9 is located in the compressed air supply pipeline 1 and at a location after the compressed air supply pipeline cutoff valve 3, the compressed air supply pipeline flow meter 10 is located in the compressed air supply pipeline 1 and at a location after the compressed air supply pipeline pressure gauge 9, the compressed air supply pipeline nitrogen gas blowing pipeline 7 is located at a location after the compressed air supply pipeline flow meter 10 and is connected to the compressed air supply pipeline 1, the compressed air supply pipeline nitrogen gas blowing valve 8 is located in the compressed air supply pipeline nitrogen gas blowing pipeline 7, and the end of the compressed air supply pipeline 1 is connected to the general mixed gas pipeline 36 and is located at a location before the connection point of the hot oxygen gas supply pipeline 11 and the general mixed gas pipeline 36.

[0009] The hot oxygen gas pipeline cutoff valve 12 is located at the start end of the hot oxygen gas supply pipeline 11, the hot oxygen gas pipeline blind valve 14 is located in the hot oxygen gas supply pipeline 11 and at a position behind the hot oxygen gas pipeline cutoff valve 12, the hot oxygen gas pipeline cutoff valve 13 is located in the hot oxygen gas supply pipeline 11 and at a position behind the hot oxygen gas pipeline blind valve 14, the hot oxygen gas pipeline vent valve 15 is located in the hot oxygen gas supply pipeline 11 and at a position behind the hot oxygen gas pipeline blind valve 14, the hot oxygen gas pipeline vent valve 16 is located in the hot oxygen gas supply pipeline 11 and at a position behind the hot oxygen gas pipeline blind valve 14 and the hot oxygen gas pipeline cutoff valve 13, The hot oxygen gas pipeline pressure meter 19 is located in the hot oxygen gas supply pipeline 11 and at a location downstream of the hot oxygen gas pipeline cutoff valve 13, the hot oxygen gas pipeline flow meter 20 is located in the hot oxygen gas supply pipeline 11 and at a location downstream of the hot oxygen gas pipeline pressure meter 19, the hot oxygen gas supply pipeline nitrogen gas blowing pipeline 17 is located at a location downstream of the hot oxygen gas supply pipeline flow meter 20 and connected to the hot oxygen gas supply pipeline 11, the hot oxygen gas supply pipeline nitrogen gas blowing valve 18 is located in the hot oxygen gas supply pipeline nitrogen gas blowing pipeline 17, and the end of the hot oxygen gas supply pipeline 11 is connected to the general mixed gas pipeline 36 and is located at a location upstream of the connection point between the general mixed gas pipeline coal gas analyzer 37 and the general mixed gas pipeline 36.

[0010] Regarding the mixed coal gas pipeline 26, the mixed coal gas pipeline cutoff valve 27, the mixed coal gas pipeline cutoff valve 28, the mixed coal gas pipeline nitrogen gas blowing pipeline 29, the mixed coal gas pipeline nitrogen gas blowing cutting valve 30, the mixed coal gas pipeline blind plate valve 31, the mixed coal gas pipeline release valve 32, the mixed coal gas pipeline release valve 33, the mixed coal gas pipeline pressure gauge 34, and the mixed coal gas pipeline flow meter 35, The mixed coal gas pipeline cutoff valve 27 is installed at the start end of the mixed coal gas pipeline 26, the mixed coal gas pipeline blind plate valve 31 is located on the mixed coal gas pipeline 26 and is installed at a position behind the mixed coal gas pipeline cutoff valve 27, the mixed coal gas pipeline cutoff valve 28 is located on the mixed coal gas pipeline 26 and is installed at a position behind the mixed coal gas pipeline blind plate valve 31, the mixed coal gas pipeline vent valve 32 is located on the mixed coal gas pipeline 26 and is installed between the mixed coal gas pipeline cutoff valve 27 and the mixed coal gas pipeline blind plate valve 31, and the mixed coal gas pipeline vent valve 33 is located on the mixed coal gas pipeline 26 and is installed between the mixed coal gas pipeline blind plate valve 31 and the mixed coal gas pipeline cutoff valve 28, The mixed coal gas pipeline pressure gauge 34 is located in the mixed coal gas pipeline 26 and is attached at a position behind the mixed coal gas pipeline cutoff valve 28, the mixed coal gas pipeline flow meter 35 is located in the mixed coal gas pipeline 26 and is attached at a position behind the mixed coal gas pipeline pressure gauge 34, the mixed coal gas pipeline nitrogen gas blowing pipeline 29 is located at a position behind the mixed coal gas pipeline flow meter 35 and is connected to the mixed coal gas pipeline 26, and the mixed coal gas pipeline nitrogen gas blowing cutoff valve 30 is attached to the mixed coal gas pipeline nitrogen gas blowing pipeline 29, and the end of the mixed coal gas pipeline 26 is joined to the end of the high-stability nitrogen gas pipeline 21 and connected to the start end of the overall mixed gas pipeline 36.

[0011] A high-stability nitrogen gas pipeline pressure meter 24 and a high-stability nitrogen gas flow meter 25 are sequentially installed at the starting end of the high-stability nitrogen gas pipeline 21, and a high-stability nitrogen gas cut-off valve 22 and a high-stability nitrogen gas cut-off valve 23 are sequentially installed at a location in the high-stability nitrogen gas pipeline 21 after the high-stability nitrogen gas flow meter 25, and the end of the high-stability nitrogen gas pipeline 21 is joined to the end of the mixed coal gas pipeline 26 and connected to the starting end of the general mixed gas pipeline 36.

[0012] The end of the general mixed gas line 36 is connected to the coal gas heating furnace, and the general mixed gas line coal gas analyzer 37 is connected to the general mixed gas line 36 before the coal gas heating furnace.

[0013] The present invention provides the following technical solutions: A ventilation method for treating long-term shutdowns or abnormal furnace conditions in a hydrogen-enriched, carbon-circulating oxygen blast furnace, When switching the ventilation mode in a hydrogen-enriched, carbon-circulating oxygen blast furnace before a long-term shutdown or when the furnace is in an abnormal state (furnace cooling, freezing of furnace cans, etc.), The normal operation state of the hydrogen-enriched carbon-circulation oxygen blast furnace is in a mode of blowing a mixture of hot coal gas, cold oxygen gas, and high-stability nitrogen gas. At least one smelting cycle before the smelting stop, the blowing of hot coal gas and cold oxygen gas is stopped. Before the blowing of hot coal gas is stopped, the theoretical combustion temperature is controlled to be in the range of 1900-2400°C, and a pressure reduction operation is performed by reducing the blowing amount of coal gas and the blowing amount of oxygen gas. After the blowing of hot coal gas is stopped, the blowing amount of oxygen gas is reduced until the blowing of oxygen gas is stopped, so that the content of oxygen gas in the overall blowing amount is controlled to be 25% or less. In step S1, specifically, high-stability nitrogen gas is passed through, and the high-stability nitrogen gas line control valve 44 is opened, and the high-stability nitrogen gas cutoff valves 22 and 23 are opened to control the flow rate of high-stability nitrogen gas to 5000m3 / h. Stop the injection of hot coal gas by adjusting the mixed coal gas pipeline control valve 43, reducing the amount of mixed coal gas injected until the opening of the control valve becomes 0, closing the mixed coal gas pipeline cutoff valve 27, opening the mixed coal gas pipeline nitrogen gas blow-off valve 30, blowing for 1 minute, then closing the mixed coal gas pipeline cutoff valve 28, opening the mixed coal gas pipeline release valve 32 and the mixed coal gas pipeline release valve 33, closing the mixed coal gas pipeline nitrogen gas blow-off valve 30, and closing the mixed coal gas pipeline blind valve 31; Stopping the injection of cold oxygen gas 39; Injecting hot compressed air, confirming that the compressed air line cutoff valve 2 and the compressed air line cutoff valve 3 are closed, opening the compressed air line blind valve 4, closing the compressed air line release valve 5 and the compressed air line release valve 6, opening the compressed air line cutoff valve 2 and the compressed air line cutoff valve 3, and adjusting and controlling the flow rate of the compressed air by the compressed air line adjustment valve 41; Injecting hot oxygen gas, confirming that the hot oxygen gas pipeline cutoff valve 12 and the hot oxygen gas pipeline cutoff valve 13 are closed, opening the hot oxygen gas pipeline blind valve 14, closing the hot oxygen gas pipeline release valve 15 and the hot oxygen gas pipeline release valve 16, opening the hot oxygen gas pipeline cutoff valve 12 and the hot oxygen gas pipeline cutoff valve 13, and adjusting and controlling the flow rate of the hot oxygen gas by the hot oxygen gas pipeline control valve 42; Step S1: adjusting blast parameters, including adjusting the flow rates of compressed air, hot oxygen gas, and nitrogen gas to desired values, and controlling the oxygen gas content in the overall blast volume of the mixed gas to be within the range of 21-25% during this period; in this blast mode, after at least one smelting cycle has elapsed, the blast furnace is in a blast stop state; A step S2 of re-blowing, When re-ventilating after a long period of shutdown or shutdown due to abnormal furnace conditions, before re-ventilating, ensure that half of the tuyere near the pig-hole is open and the other half away from the pig-hole is closed, and then re-ventilate half of the tuyere. During the re-ventilation process, the ventilating mode of hot compressed air, hot oxygen gas, and hot nitrogen gas mixture is still selected, that is, high-stability nitrogen gas is blown and the system is blown for 1 minute. In accordance with the procedure of blowing hot compressed air and blowing hot oxygen gas in step S1, the operation is performed by adjusting the ventilating parameters, and the oxygen gas content in the overall ventilating volume during the re-ventilation process is controlled to be within the range of 21-25%. After re-ventilation, the furnace conditions are restored using this ventilating method in step S2. When switching the ventilation mode after the furnace condition is restored, When the furnace conditions are gradually restored, the furnace temperature is normal, the iron tapping at the furnace front is normal, the charge charging is normal, and the number of open tuyeres accounts for 80% or more of the total number of tuyeres, step S3 switches the operation from the mixed gas blowing mode of hot compressed air, hot oxygen gas, and hot nitrogen gas to the mixed gas blowing mode of hot coal gas, hot oxygen gas, and highly stable nitrogen gas, and specifically, stops the blowing of hot oxygen gas by opening the hot oxygen gas line nitrogen gas blowing valve 18 and adjusting the hot oxygen gas line control valve 42 to reduce the blowing amount of hot oxygen gas until the flow rate of hot oxygen gas becomes 0, closing the hot oxygen gas line cutoff valve 12 and the hot oxygen gas line cutoff valve 13, opening the hot oxygen gas line release valve 15 and the hot oxygen gas line release valve 16, closing the hot oxygen gas line nitrogen gas blowing valve 18, and closing the hot oxygen gas line blind valve 14; Stopping the blowing of hot compressed air, after stopping the blowing of hot oxygen gas, opening the compressed air line nitrogen gas blowing valve 8, adjusting the compressed air line control valve 41 to reduce the blowing amount of compressed air until the flow rate of compressed air becomes 0, closing the compressed air line cutoff valve 2 and the compressed air line cutoff valve 3, opening the compressed air line release valve 5 and the compressed air line release valve 6, closing the compressed air line nitrogen gas blowing valve 8, and closing the compressed air line blind valve 4; Injecting cold oxygen gas, sending cold oxygen gas 39 through the tuyere of the blast furnace, adjusting the injection amount of cold oxygen gas, controlling the oxygen gas content in the overall blast volume of the mixed gas to be within the range of 21-25% during that period, and confirming that the operation of the blast furnace is normal when the injection amount of cold oxygen gas increases to the maximum under the condition that the oxygen gas content in the overall blast volume is controlled to be within the range of 21-25%; and a step S3 of injecting hot coal gas, the step including: confirming that the mixed coal gas pipeline cutoff valves 27 and 28 are closed; opening the mixed coal gas pipeline blind valve 31; opening the mixed coal gas pipeline nitrogen gas blow-off valve 30; closing the mixed coal gas pipeline vent valves 32 and 33; opening the mixed coal gas pipeline cutoff valves 27 and 28; and adjusting the mixed coal gas pipeline control valve 43, thereby gradually increasing the mixed coal gas injection rate until the operation and production requirements can be met; and closing the mixed coal gas pipeline nitrogen gas blow-off valve 30 when the mixed coal gas injection rate exceeds 5000 m3 / h. [Example]

[0014] The following describes an example of restoring furnace conditions according to the above method, taking the HY blast furnace of the Xinjiang Baguang low-carbon test platform as the implementation object.

[0015] At 11:15 on May 25, 2023, scheduled maintenance work was completed in the blast furnace work area of ​​the hydrogen-enriched, carbon-circulating oxygen blast furnace process HY. This scheduled maintenance work mainly included the local replacement of the blower in the tuyere, the remanufacturing of the main groove, the complete replacement of the mud gun, and the replacement of the duckbill for slag cleaning. The total duration of the maintenance work, from the start of the shutdown at 9:00 on May 24 to the start of the shutdown at 11:15 on May 25, was 1,575 minutes.

[0016] The charge structure during the blast furnace shutdown on May 24th was as follows:

[0017] [Table 1] The iron production status in the smelting cycle prior to the shutdown on May 24th is as follows:

[0018] [Table 2] From the end of regular maintenance on May 25th until the re-blow at the blast furnace, the charge charging mode at the blast furnace was as follows: 2P 24.5° 6 rotations↓ 2K 24.5° 6 rotations↓ Stock line: 1.6m.

[0019] The re-ventilation method in the blast furnace is as follows: A re-ventilation method using a mixture of nitrogen gas, cold oxygen gas, and hot coal gas is used, and the (14) tuyeres are fully opened to ventilate. The ventilating parameters for re-ventilation are set as follows:

[0020] [Table 3] The status of tapping iron in front of the blast furnace after blasting at 11:50 on May 25th was as follows:

[0021] [Table 4] Blast air started at 11:50 on May 25th, and from 12:18 the stock rod in the south was set to 1.42m and the stock rod in the north to 1.24m. Without operating the stock line, it was determined that the blast furnace was hanging, the hot blast pressure was set to 155kpa, and the pressure difference was 84kpa. At 14:27 a slip accident suddenly occurred, and the stock rod in the south was changed from 1.42m to 2.47m and the stock rod in the north from 1.24m to 2.32m, the hot blast pressure was set to 117kpa, and the pressure difference was 31kpa.

[0022] After the slippage occurred, the liquid level in the expansion tank of the blast furnace dropped rapidly, and the amount of soft water added increased. At the same time, an inspection of the water flow rate trends in the small sleeves revealed that the 2, 3, and 6# small sleeves showed signs of leakage, with the difference in inflow and outflow water volume reaching 7L / min. An inspection of the cooling water system at the blast furnace site confirmed leakage in the 4# and 5# large sleeves and the 2, 3, and 6# small sleeves. The furnace was shut down at 20:05 on May 25th. After this re-ventilation, a total of 26 patches of charge were charged.

[0023] At 8:05 PM on May 25th, the furnace was shut down, and the #4 and #5 large sleeves were replaced, along with the #2, #3, #4, #5, and #6 small sleeves. By the time the blowing was shut down, the soft water supply volume had reached 31.67 m3. At 1:40 PM on May 26th, the replacement of the blower, which had been leaking from the tuyere, was completed, and the blast furnace was re-blow. During this re-blow process, the parameters of the charge charging system at the blast furnace were as follows: ore batch: 14.5 t, coke batch: 4.78 t, coke rate: 515.3 kg / t, load: 3.021, charge charging mode: 2P 24.5° 6 rotations ↓, 2K 24.5° 6 rotations ↓, stock line: 1.6 m. The re-blow method at the blast furnace was as follows: A blowing-type re-ventilation method using a mixture of nitrogen gas, cold oxygen gas, and hot coal gas is used, and 11 tuyeres are blown, and the blowing parameters during re-ventilation are set as follows:

[0024] [Table 5] After the re-blow, the pig hole was opened once around 15:00, and a small amount of red slag was ejected. Immediately after a large amount of slag was ejected from the pig hole, the pig hole was plugged. There were 11 blast tuyere units, and tuyere units 3, 4, and 5 were plugged with mud guns. After the blast, the tuyere units operated normally, and the stock line operated smoothly. At 15:07 on May 26, coke oven gas injection into the blast furnace began. At 15:08, a small pipe line appeared in the blast furnace, and the top pressure rose to 184 kPa and the top temperature rose to 135°C. After the pipeline appeared, the stock rod in the north suddenly increased from 1.94m to 4.08m, and the stock rod in the south suddenly increased from 2.24m to 3.86m. Shortly after, an abnormality was discovered in the difference in the amount of water entering and exiting the 6#7#8#9#11# small sleeves, and the liquid level in the expansion tank of the blast furnace dropped rapidly. After checking the water condition and ordering an observation of the tuyere condition, the tuyere was reported to have turned completely black. An on-site inspection revealed that there was a water leak in the 6#7#8#9#11# small sleeves and the 6# large sleeve. At 4:20 PM, the operation was stopped and the damaged blower equipment replaced. At the morning meeting held at 8:18 on May 27, each department resolved to treat the accident as a furnace cooling accident. During the day shift on May 27, oxygen gas was used in the 1#14# tuyere (the 1#2#13#14# small sleeves were replaced with small sleeves in both chambers), and oxygen gas guns were installed in the blast holes. Re-blow of the blast furnace was conducted again at 20:25 on May 27. The parameters of the charge charging system for the blast furnace during this re-blow were as follows: ore batch: 12t, coke batch: 5.3t, coke rate: 698kg / t, load: 2.26, charge charging mode: 2P 23.5° 6 rotations↓, 3K 23.5° 8 rotations↓, stock line: 1.6m.

[0025] The re-ventilation method used in blast furnaces is a re-ventilation method using a mixture of nitrogen gas, hot oxygen gas, and hot compressed air. There are four ventilating tuyeres in this case, and ventilating is performed using tuyeres 1#, 2#, 13#, and 14#. The remaining tuyeres are blocked with firebricks or cement to completely block excess nitrogen gas from the tuyeres. The BP is set to 170kPa, the air speed is set to 200m / s or more, the pressure difference is set to 140kPa or less, and the oxygen gas content in the blown amount is set to 25% or less. The ventilating parameters for this re-ventilation are set as follows:

[0026] [Table 6] At approximately 3:20 AM on May 28, an on-site inspection discovered a water leak in the antechamber of the #13 small sleeve. Water volume control was performed with a 7.5m3 area, and nitrogen gas was used to maintain the tuyere. The blast furnace's condition gradually returned to normal. At approximately 6:00 PM on May 28, the pit was filled with hot metal, restoring normal operation. At approximately 6:30 AM on May 29, all tuyere openings except for #8 and #9 tuyere openings were completed. At approximately 6:00 PM, cold oxygen gas was injected into the tuyere openings. At approximately 7:00 PM, decarbonized coal gas was introduced into the blast furnace. At approximately 11:00 PM, coke oven gas was introduced into the blast furnace. By this point, the blast furnace cooling incident was essentially resolved, and operating parameters were gradually restored. By May 30, operating parameters and the hydrogen-enriched, carbon-recycling oxygen blast furnace had essentially returned to normal. The Si level in the blast furnace has dropped to 0.74, completing the response to the blast furnace accident.

Claims

1. A method for blowing air during a long-term cessation of blowing in a hydrogen-enriched and carbon-circulating oxygen blast furnace, comprising: In the hydrogen-enriched and carbon-circulating oxygen blast furnace, before the long-term blast stop or when the furnace is in an abnormal state, the blast mode is switched as follows: The normal operation state of the hydrogen-enriched carbon-circulation oxygen blast furnace is a mode in which hot coal gas, cold oxygen gas, and highly stable nitrogen gas are mixed and blown. At least one smelting cycle before the cessation of blowing, the blowing of the hot coal gas and the cold oxygen gas is stopped, and before the blowing of the hot coal gas is stopped, a pressure reduction operation is performed by reducing the blowing amount of the coal gas and the blowing amount of the oxygen gas, while controlling the theoretical combustion temperature to be in the range of 1900 to 2400°C. After the blowing of the hot coal gas is stopped, the content of oxygen gas in the overall blowing amount is controlled to be 25% or less until the blowing of the oxygen gas is stopped, and an operation of reducing the blowing amount of the oxygen gas is performed. Specifically, Passing high-stability nitrogen gas, opening the high-stability nitrogen gas pipeline control valve (44) and opening the high-stability nitrogen gas pipeline cutoff valves (22, 23), and controlling the flow rate of the high-stability nitrogen gas to 5000 m3 / h; stopping the injection of the hot coal gas by adjusting the mixed coal gas pipeline control valve (43) to reduce the amount of mixed coal gas injected until the opening of the control valve becomes 0, closing the mixed coal gas pipeline cutoff valve (27), opening the mixed coal gas pipeline nitrogen gas blow-off valve (30), blowing for one minute, closing the mixed coal gas pipeline cutoff valve (28), opening the mixed coal gas pipeline release valve (32) and the mixed coal gas pipeline release valve (33), closing the mixed coal gas pipeline nitrogen gas blow-off valve (30), and closing the mixed coal gas pipeline blind valve (31); stopping the blowing of the cold oxygen gas (39); Injecting hot compressed air, confirming that the compressed air line cutoff valve (2) and the compressed air line cutoff valve (3) are closed, opening the compressed air line blind valve (4), closing the compressed air line release valve (5) and the compressed air line release valve (6), opening the compressed air line cutoff valve (2) and the compressed air line cutoff valve (3), and adjusting and controlling the flow rate of the compressed air by the compressed air line adjustment valve (41); Injecting hot oxygen gas, confirming that the hot oxygen gas pipeline cutoff valve (12) and the hot oxygen gas pipeline cutoff valve (13) are closed, opening the hot oxygen gas pipeline blind valve (14), closing the hot oxygen gas pipeline release valve (15) and the hot oxygen gas pipeline release valve (16), opening the hot oxygen gas pipeline cutoff valve (12) and the hot oxygen gas pipeline cutoff valve (13), and adjusting and controlling the flow rate of the hot oxygen gas by the hot oxygen gas pipeline control valve (42); Step (S1) of adjusting blast parameters, including adjusting the flow rates of compressed air, hot oxygen gas, and nitrogen gas to desired values, and controlling the oxygen gas content in the overall blast volume of the mixed gas to be within the range of 21-25% during that period, and in this blast mode, after at least one smelting cycle has elapsed, the blast furnace is in a blast stop state; A step (S2) of re-blowing air, When re-ventilation is performed after the long-term ventilating stop or ventilating stop due to abnormal furnace conditions, before re-ventilation, half of the tuyere close to the pig-hole is opened and the other half away from the pig-hole is closed, and re-ventilation is performed using half of the tuyere. During the re-ventilation process, the ventilating mode using a mixture of hot compressed air, hot oxygen gas, and hot nitrogen gas is still selected, that is, high-stability nitrogen gas is blown and the system is blown for 1 minute. According to the procedure of blowing hot compressed air and blowing hot oxygen gas in step S1, the operation is performed by adjusting the ventilating parameters, and the content of oxygen gas in the overall ventilating volume during the re-ventilation process is controlled to be within the range of 21-25%. After re-ventilation, the furnace conditions are restored using this ventilating method (step S2). When switching the ventilation mode after the furnace condition is restored, When the furnace conditions are gradually restored, the furnace temperature becomes normal, the iron tapping at the furnace front becomes normal, the charge charging becomes normal, and the number of open tuyeres accounts for 80% or more of the total number of tuyeres, the operation is switched from a blast mode using a mixed gas of hot compressed air, hot oxygen gas, and hot nitrogen gas to a blast mode using a mixed gas of hot coal gas, hot oxygen gas, and highly stable nitrogen gas (S3), specifically: Stopping the blowing of hot oxygen gas, by opening the hot oxygen gas line nitrogen gas blowing valve (18), adjusting the hot oxygen gas line control valve (42) to reduce the blowing amount of hot oxygen gas until the flow rate of hot oxygen gas becomes 0, closing the hot oxygen gas line cutoff valve (12) and the hot oxygen gas line cutoff valve (13), opening the hot oxygen gas line release valve (15) and the hot oxygen gas line release valve (16), closing the hot oxygen gas line nitrogen gas blowing valve (18), and closing the hot oxygen gas line blind valve (14); Stopping the blowing of hot compressed air, after stopping the blowing of hot oxygen gas, opening the compressed air line nitrogen gas blowing valve (8), adjusting the compressed air line control valve (41) to reduce the blowing amount of compressed air until the flow rate of compressed air becomes 0, closing the compressed air line cutoff valve (2) and the compressed air line cutoff valve (3), opening the compressed air line release valve (5) and the compressed air line release valve (6), closing the compressed air line nitrogen gas blowing valve (8), and closing the compressed air line blind valve (4); Injecting cold oxygen gas, sending cold oxygen gas (39) through the tuyere of the blast furnace, adjusting the injection amount of cold oxygen gas, controlling the oxygen gas content in the overall blast volume of the mixed gas to be within the range of 21-25% during that period, and confirming that the blast furnace is operating normally when the injection amount of cold oxygen gas reaches its maximum under the condition that the oxygen gas content in the overall blast volume is controlled to be within the range of 21-25%; and a step (S3) of injecting hot coal gas, the step including: confirming that the mixed coal gas pipeline cutoff valve (27) and the mixed coal gas pipeline cutoff valve (28) are closed; opening the mixed coal gas pipeline blind valve (31); opening the mixed coal gas pipeline nitrogen gas blow-off valve (30); closing the mixed coal gas pipeline vent valve (32) and the mixed coal gas pipeline vent valve (33); opening the mixed coal gas pipeline cutoff valve (27) and the mixed coal gas pipeline cutoff valve (28); and adjusting the mixed coal gas pipeline control valve (43) to gradually increase the amount of mixed coal gas injected until operation and production requirements can be met; and closing the mixed coal gas pipeline nitrogen gas blow-off valve (30) after the amount of mixed coal gas injected exceeds 5,000 m / h.

2. A method for blowing air during long-term shutdown in a hydrogen-enriched, carbon-circulating oxygen blast furnace, comprising: controlling the pressure of hot oxygen gas to be within a range of 0.55 to 0.6 MPa using a pressure gauge in a hot oxygen gas pipeline; controlling the pressure of compressed air to be within a range of 0.55 to 0.6 MPa using a pressure gauge in a compressed air pipeline; controlling the pressure of mixed coal gas to be within a range of 0.55 to 0.6 MPa using a pressure gauge in the mixed coal gas pipeline; and controlling the pressure of highly stable nitrogen gas to be within a range of 0.6 to 0.65 MPa using a pressure gauge in the highly stable nitrogen gas pipeline.

3. The method for blowing air during a long-term shutdown in a hydrogen-enriched and carbon-circulating oxygen blast furnace according to claim 1, characterized in that the chain protection is set so that the highly stable nitrogen gas pressure - compressed air pressure is greater than 0.05 MPa, otherwise, the compressed air control valve and the shutoff valve will all be automatically closed in a chain reaction.

4. The method for long-term ventilation in a hydrogen-enriched and carbon-circulating oxygen blast furnace according to claim 1, characterized in that the chain protection is set so that the highly stable nitrogen gas pressure - hot oxygen gas pressure > 0.05 MPa, otherwise, the hot oxygen gas control valve and cut-off valve will all be automatically closed in a chain reaction.

5. The method for blowing air during a long-term shutdown in a hydrogen-enriched and carbon-circulating oxygen blast furnace according to claim 1, characterized in that the chain protection is set so that the highly stable nitrogen gas pressure - the mixed coal gas pressure is greater than 0.05 MPa, otherwise, the mixed coal gas control valve and the cutoff valve will all be automatically closed in a chain reaction.

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