Method for supplying air during prolonged shutdown in a hydrogen-enriched, carbon-cycle type 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 belongs to the technical field of blast furnace ironmaking, and specifically relates to a blowing method for a long-term blast outage in a hydrogen-enriched and carbon-circulating oxygen blast furnace.

Background Art

[0002] In the case of a long-term blast outage and reblowing in a hydrogen-enriched and carbon-circulating oxygen blast furnace, or in the case of abnormal furnace conditions such as the hearth being frozen or a furnace cooling accident occurring, when dealing with reblowing or coping with abnormal furnace conditions, as a general operation method for a hydrogen-enriched and carbon-circulating oxygen blast furnace, after blowing high-stability nitrogen gas and spraying it, cold oxygen gas is blown in and ignited, and then through the coal gas for mixed blowing, the blowing amount of the coal gas for mixed blowing is increased to reduce the amount of nitrogen gas. However, in that process, the content of oxygen gas in the blowing amount is too high, the hearth becomes inert, the swirling region at the tuyere is short, the metallization rate of smelting by blowing coal gas with all oxygen is high, and the blowing device at the tuyere is easily burned and damaged. Therefore, with this method, when restoring the furnace condition of a hydrogen-enriched and carbon-circulating oxygen blast furnace, it is easy to cause the deterioration of the furnace condition to progress, and during the process of restoring the furnace condition, repeated blast outages and reblowings are also likely to occur.

Summary of the Invention

[0003] The present invention aims to provide a blowing method for a long-term blast outage in a hydrogen-enriched and carbon-circulating oxygen blast furnace. According to this method, when restoring the furnace condition of a hydrogen-enriched and carbon-circulating oxygen blast furnace by a general reblowing method, the problem that it is easy to cause the deterioration of the furnace condition to progress and repeated blast outages and reblowings are also likely to occur during the process of restoring the furnace condition can be effectively solved.

[0004] A blowing method for a long-term blast outage in a hydrogen-enriched and carbon-circulating oxygen blast furnace, In the switching of the blowing mode before a long-term blast outage in a hydrogen-enriched and carbon-circulating oxygen blast furnace or in an abnormal state of the furnace condition, The normal operating state of the hydrogen-enriched, carbon-recycling oxygen blast furnace is a mode in which hot coal gas, cold oxygen gas, and highly stable nitrogen gas are mixed and blown. Step S1 involves stopping the injection of hot coal gas and cold oxygen gas at least one smelting cycle before the shutdown, controlling the theoretical combustion temperature to be within the range of 1900-2400°C, and performing a depressurization operation by reducing the amount of coal gas and oxygen gas injected. After stopping the injection of hot coal gas, the oxygen gas content in the overall airflow is controlled to be 25% or less until the injection of oxygen gas stops, and performing an operation to reduce the amount of oxygen gas injected. Specifically, this involves passing highly stable nitrogen gas through, opening the highly stable nitrogen gas pipeline control valve 44, opening the highly stable nitrogen gas cut-off valves 22 and 23, and controlling the flow rate of highly stable nitrogen gas to 5000 m3 / h. The procedure involves stopping the injection of hot coal gas by adjusting the mixed coal gas pipeline control valve 43 to reduce the amount of mixed coal gas injected until the valve opening becomes 0, closing the mixed coal gas pipeline cutting valve 27, opening the mixed coal gas pipeline nitrogen gas blowing cutting valve 30 and blowing for 1 minute, then closing the mixed coal gas pipeline cutting valve 28, opening the mixed coal gas pipeline release valves 32 and 33, closing the mixed coal gas pipeline nitrogen gas blowing cutting valve 30, and closing the mixed coal gas pipeline blind plate valve 31. Stop blowing in cold oxygen gas 39, This involves blowing in hot compressed air, confirming that the compressed air pipeline cutting valve 2 and the compressed air pipeline cutting valve 3 are closed, opening the compressed air pipeline blind plate valve 4, closing the compressed air pipeline release valve 5 and the compressed air pipeline release valve 6, opening the compressed air pipeline cutting valve 2 and the compressed air pipeline cutting valve 3, and adjusting and controlling the flow rate of compressed air with the compressed air pipeline control valve 41. This involves blowing in hot oxygen gas, confirming that the hot oxygen gas pipeline cutting valve 12 and the hot oxygen gas pipeline cutting valve 13 are closed, opening the hot oxygen gas pipeline blind plate 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 cutting valve 12 and the hot oxygen gas pipeline cutting valve 13, and adjusting and controlling the flow rate of hot oxygen gas with the hot oxygen gas pipeline control valve 42. Step S1 involves adjusting the blowing parameters, which includes adjusting the flow rates of compressed air, hot oxygen gas, and nitrogen gas to desired values, and controlling the oxygen gas content in the total blowing rate of the mixed gas to be within the range of 21-25% during that period, wherein in this blowing mode, the blast furnace enters a shut-off state after at least one smelting cycle has elapsed, Step S2 involves re-air supplying, When restarting ventilation after a prolonged shutdown or shutdown due to abnormal furnace conditions, before restarting ventilation, ensure that the half of the tuyeres closest to the pig nozzle is open and the other half away from the pig nozzle is closed, restart ventilation is performed at half of the tuyeres, and during the restarting process, select the ventilation mode using a mixture of hot compressed air, hot oxygen gas, and hot nitrogen gas, that is, blow highly stable nitrogen gas through the system for 1 minute, blow in hot compressed air in step S1, blow in hot oxygen gas, and operate by adjusting the ventilation parameters according to the procedure, controlling the oxygen gas content in the overall ventilation volume during the restarting process to be within the range of 21-25%, and after restarting ventilation, perform step S2 to restore the furnace conditions using that ventilation method. When switching the fan mode after restoring the furnace conditions, When the furnace conditions gradually recover, the furnace temperature returns to normal, tapping from the furnace front returns to normal, charging returns to normal, and the number of open tuyeres accounts for 80% or more of the total number of tuyeres, operation S3 involves switching from a blowing mode using a mixture of hot compressed air, hot oxygen gas, and hot nitrogen gas to a blowing mode using a mixture of hot coal gas, hot oxygen gas, and highly stable nitrogen gas. Specifically, this involves stopping the injection of hot oxygen gas by opening the hot oxygen gas pipeline nitrogen gas injection valve 18 and adjusting the hot oxygen gas pipeline control valve 42 to reduce the amount of hot oxygen gas injected until the flow rate of hot oxygen gas becomes 0, closing the hot oxygen gas pipeline cutting valve 12 and the hot oxygen gas pipeline cutting valve 13, opening the hot oxygen gas pipeline release valve 15 and the hot oxygen gas pipeline release valve 16, closing the hot oxygen gas pipeline nitrogen gas injection valve 18, and closing the hot oxygen gas pipeline blind plate valve 14. The process involves stopping the injection of hot compressed air, stopping the injection of hot oxygen gas, then opening the compressed air pipeline nitrogen gas injection valve 8 and adjusting the compressed air pipeline control valve 41 to reduce the amount of compressed air injected until the compressed air flow rate becomes 0, closing the compressed air pipeline cutting valve 2 and the compressed air pipeline cutting valve 3, opening the compressed air pipeline release valve 5 and the compressed air pipeline release valve 6, closing the compressed air pipeline nitrogen gas injection valve 8, and closing the compressed air pipeline blind plate valve 4. This involves blowing in cold oxygen gas, supplying cold oxygen gas 39 through the tuyeres of the blast furnace, adjusting the amount of cold oxygen gas injected, and controlling the oxygen content of the total airflow of the mixed gas to be within the range of 21-25% during that period. Under the condition that the oxygen content of the total airflow is controlled to be within the range of 21-25%, it is confirmed that the blast furnace operation is normal when the amount of cold oxygen gas injected is increased to its maximum. The present invention provides a method for supplying air for extended periods of shutdown in a hydrogen-enriched, carbon-recycling oxygen blast furnace, comprising step S3, which includes blowing in hot coal gas, confirming that the mixed coal gas pipeline cutting valve 27 and the mixed coal gas pipeline cutting valve 28 are closed, opening the mixed coal gas pipeline blind plate valve 31, opening the mixed coal gas pipeline nitrogen gas blow cutting valve 30, closing the mixed coal gas pipeline release valve 32 and the mixed coal gas pipeline release valve 33, opening the mixed coal gas pipeline cutting valve 27 and the mixed coal gas pipeline cutting valve 28, and adjusting the mixed coal gas pipeline control valve 43 to gradually increase the amount of mixed coal gas blown in until the operational and production requirements can be satisfied, and closing the mixed coal gas pipeline nitrogen gas blow cutting valve 30 after the amount of mixed coal gas blown in exceeds 5000 m3 / h. Since hydrogen-enriched, carbon-recycling oxygen blast furnaces have a much weaker heat storage capacity than conventional blast furnaces, this invention addresses the process of handling abnormal furnace conditions such as prolonged blast shutdowns, furnace freezing, or furnace cooling accidents in a hydrogen-enriched, carbon-recycling oxygen blast furnace by switching to a blowing mode using a mixed gas of hot compressed air, hot oxygen gas, and hot nitrogen gas from the cycle immediately preceding the blast shutdown. This mode is similar to the blowing mode used in conventional blast furnace smelting, significantly reducing indirect reduction reactions within the furnace and lowering the metallization rate of the charge. Furthermore, by supplementing with coke instead of coal gas for injection, the coke bed area in the furnace can be expanded, improving the permeability of the blast furnace. After re-blowing, good permeability is easily achieved in the blast furnace, increasing the activity of the furnace. When re-blowing is performed, the tuyeres are half open and half closed, reducing the probability of burnout of the blowing device at the tuyeres and subsequent water leakage due to furnace inertness. Furthermore, selecting a blowing mode using a mixture of hot compressed air, hot oxygen gas, and hot nitrogen gas as the blowing mode during re-blowing is also done to better control the oxygen content in the local total blowing amount in the furnace and the intensity of smelting. As the activity of the furnace and the permeability of the hydrogen-enriched, carbon-recycled oxygen blast furnace gradually improve, the blocked tuyeres are gradually opened, and when the number of open tuyeres exceeds 80%, the blast furnace may be considered to have met the requirements to switch to the general smelting mode of the hydrogen-enriched, carbon-recycled oxygen blast furnace, in which case further switching of the blowing mode is recommended. Compared to the general blowing mode of conventional hydrogen-enriched, carbon-recycled oxygen blast furnaces, the method in the present invention is superior in terms of restoring the furnace condition of the hydrogen-enriched, carbon-recycled oxygen blast furnace. [Brief explanation of the drawing]

[0005] [Figure 1] This is a flowchart of the airflow mode switching system in the present invention. [Modes for carrying out the invention]

[0006] The following will clearly and completely describe the technical concepts in embodiments of the present invention with reference to Figure 1. It is clear that the embodiments described are only a subset of, not all, embodiments of the present invention. All other embodiments that can be obtained based on the embodiments of the present invention, without requiring any creative effort from those skilled in the art, are all within the scope of the protection of the present invention.

[0007] As shown in Figure 1, in the long-duration shutoff ventilation method for a hydrogen-enriched, carbon-cycle type oxygen blast furnace according to the present invention, the ventilation mode switching system consists of a compressed air supply pipeline 1, a compressed air pipeline cutting valve 2, a compressed air pipeline cutting valve 3, a compressed air pipeline blind plate valve 4, a compressed air pipeline release valve 5, a compressed air pipeline release valve 6, a compressed air pipeline nitrogen gas blowing pipeline 7, a compressed air pipeline nitrogen gas blowing valve 8, a compressed air pipeline pressure gauge 9, a compressed air pipeline flow meter 10, a hot oxygen gas supply pipeline 11, a hot oxygen gas pipeline cutting valve 12, a hot oxygen gas pipeline cutting valve 13, a hot oxygen gas pipeline blind plate valve 14, a hot oxygen gas pipeline release valve 15, a hot oxygen gas pipeline release valve 16, a hot oxygen gas pipeline nitrogen gas blowing pipeline 17, a hot oxygen gas pipeline nitrogen gas blowing valve 18, a hot oxygen gas pipeline pressure gauge 19, a hot oxygen gas pipeline flow meter 20, and a highly stable nitrogen gas Pipeline 21, High-stability nitrogen gas cut-off valve 22, High-stability nitrogen gas cut-off 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 cut-off valve 27, Mixed coal gas pipeline cut-off valve 28, Mixed coal gas pipeline nitrogen gas blown pipeline 29, Mixed coal gas pipeline nitrogen gas blown cut-off valve 30, Mixed coal gas pipeline blind plate valve 31, Mixed coal gas pipeline discharge valve Includes 32, a mixed coal gas pipeline release valve 33, a mixed coal gas pipeline pressure gauge 34, a mixed coal gas pipeline flow meter 35, a general mixed gas pipeline 36, a general mixed gas pipeline coal gas analyzer 37, a coal gas heating furnace 38, a cold oxygen pipeline 39, a hydrogen-enriched / carbon-recycling oxygen blast furnace 40, a compressed air pipeline control valve 41, a hot oxygen gas pipeline control valve 42, a mixed coal gas pipeline control valve 43, and a highly stable nitrogen gas pipeline control valve 44.

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

[0009] The hot oxygen gas pipeline cut-off valve 12 is located at the beginning of the hot oxygen gas supply pipeline 11, the hot oxygen gas pipeline blind plate valve 14 is located in the hot oxygen gas supply pipeline 11 and at one location after the hot oxygen gas pipeline cut-off valve 12, the hot oxygen gas pipeline cut-off valve 13 is located in the hot oxygen gas supply pipeline 11 and at one location after the hot oxygen gas pipeline blind plate valve 14, the hot oxygen gas pipeline release valve 15 is located in the hot oxygen gas supply pipeline 11 and between the hot oxygen gas pipeline cut-off valve 12 and the hot oxygen gas pipeline blind plate valve 14, the hot oxygen gas pipeline release valve 16 is located in the hot oxygen gas supply pipeline 11 and between the hot oxygen gas pipeline blind plate valve 14 and the hot oxygen gas pipeline cut-off valve 13, and the hot oxygen gas pipeline The pipe pressure gauge 19 is located in the hot oxygen gas supply pipeline 11 and at one location after the hot oxygen gas pipeline disconnection valve 13; the hot oxygen gas pipeline flow meter 20 is located in the hot oxygen gas supply pipeline 11 and at one location after the hot oxygen gas pipeline pressure gauge 19; the hot oxygen gas pipeline nitrogen gas injection pipeline 17 is located at one location after the hot oxygen gas pipeline flow meter 20 and connected to the hot oxygen gas supply pipeline 11; the hot oxygen gas pipeline nitrogen gas injection valve 18 is located in the hot oxygen gas pipeline nitrogen gas injection pipeline 17; the end of the hot oxygen gas supply pipeline 11 is connected to the general mixed gas pipeline 36 and at one location before 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, mixed coal gas pipeline cutting valve 27, mixed coal gas pipeline cutting valve 28, mixed coal gas pipeline nitrogen gas blown pipeline 29, mixed coal gas pipeline nitrogen gas blown cutting valve 30, mixed coal gas pipeline blind plate valve 31, mixed coal gas pipeline release valve 32, mixed coal gas pipeline release valve 33, mixed coal gas pipeline pressure gauge 34, and mixed coal gas pipeline flow meter 35, The mixed coal gas pipeline cutting valve 27 is installed at the beginning end of the mixed coal gas pipeline 26, the mixed coal gas pipeline blind plate valve 31 is located in the mixed coal gas pipeline 26 and installed at one location after the mixed coal gas pipeline cutting valve 27, the mixed coal gas pipeline cutting valve 28 is located in the mixed coal gas pipeline 26 and installed at one location after the mixed coal gas pipeline blind plate valve 31, the mixed coal gas pipeline release valve 32 is located in the mixed coal gas pipeline 26 and installed between the mixed coal gas pipeline cutting valve 27 and the mixed coal gas pipeline blind plate valve 31, the mixed coal gas pipeline release valve 33 is located in the mixed coal gas pipeline 26 and installed between the mixed coal gas pipeline blind plate valve 31 and the mixed coal gas pipeline cutting valve 28, The mixed coal gas pipeline pressure gauge 34 is located in the mixed coal gas pipeline 26 and is installed at one location after the mixed coal gas pipeline cut-off valve 28. The mixed coal gas pipeline flow meter 35 is located in the mixed coal gas pipeline 26 and is installed at one location after the mixed coal gas pipeline pressure gauge 34. The mixed coal gas pipeline nitrogen gas blown pipeline 29 is located at one location after the mixed coal gas pipeline flow meter 35 and is connected to the mixed coal gas pipeline 26. The mixed coal gas pipeline nitrogen gas blown cut-off valve 30 is installed in the mixed coal gas pipeline nitrogen gas blown pipeline 29. The end of the mixed coal gas pipeline 26 is joined to the end of the highly stable nitrogen gas pipeline 21 and is connected to the starting end of the general mixed gas pipeline 36.

[0011] At the starting end of the highly stable nitrogen gas pipeline 21, a highly stable nitrogen gas pressure gauge 24 and a highly stable nitrogen gas flow meter 25 are sequentially installed. At one point in the highly stable nitrogen gas pipeline 21, after the highly stable nitrogen gas flow meter 25, a highly stable nitrogen gas cut-off valve 22 and a highly stable nitrogen gas cut-off valve 23 are sequentially installed. The end of the highly stable 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 pipeline 36 was connected to a coal gas heating furnace, and the general mixed gas pipeline coal gas analyzer 37 was connected to the general mixed gas pipeline 36 in front of the coal gas heating furnace.

[0013] This invention provides the following technical solutions. A method for supplying air to treat prolonged shutdowns or abnormal furnace conditions in a hydrogen-enriched, carbon-cycle type oxygen blast furnace, In hydrogen-enriched, carbon-cycle type oxygen blast furnaces, when switching the blowing mode before a long period of shutdown or in the event of abnormal furnace conditions (furnace cooling, furnace boiler freezing, etc.), The normal operating state of the hydrogen-enriched, carbon-recycling oxygen blast furnace is a mode in which hot coal gas, cold oxygen gas, and highly stable nitrogen gas are mixed and blown. Step S1 involves stopping the injection of hot coal gas and cold oxygen gas at least one smelting cycle before the shutdown, controlling the theoretical combustion temperature to be within the range of 1900-2400°C, and performing a depressurization operation by reducing the amount of coal gas and oxygen gas injected. After stopping the injection of hot coal gas, the oxygen gas injection rate is reduced so that the oxygen gas content in the overall airflow is controlled to 25% or less until the injection of oxygen gas is stopped. Specifically, this involves passing highly stable nitrogen gas through, opening the highly stable nitrogen gas pipeline control valve 44, opening the highly stable nitrogen gas cut-off valves 22 and 23, and controlling the flow rate of highly stable nitrogen gas to 5000 m3 / h. The procedure involves stopping the injection of hot coal gas by adjusting the mixed coal gas pipeline control valve 43 to reduce the amount of mixed coal gas injected until the valve opening becomes 0, closing the mixed coal gas pipeline cutting valve 27, opening the mixed coal gas pipeline nitrogen gas blowing cutting valve 30 and blowing for 1 minute, then closing the mixed coal gas pipeline cutting valve 28, opening the mixed coal gas pipeline release valves 32 and 33, closing the mixed coal gas pipeline nitrogen gas blowing cutting valve 30, and closing the mixed coal gas pipeline blind plate valve 31. Stop blowing in cold oxygen gas 39, This involves blowing in hot compressed air, confirming that the compressed air pipeline cutting valve 2 and the compressed air pipeline cutting valve 3 are closed, opening the compressed air pipeline blind plate valve 4, closing the compressed air pipeline release valve 5 and the compressed air pipeline release valve 6, opening the compressed air pipeline cutting valve 2 and the compressed air pipeline cutting valve 3, and adjusting and controlling the flow rate of compressed air with the compressed air pipeline control valve 41. This involves blowing in hot oxygen gas, confirming that the hot oxygen gas pipeline cutting valve 12 and the hot oxygen gas pipeline cutting valve 13 are closed, opening the hot oxygen gas pipeline blind plate 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 cutting valve 12 and the hot oxygen gas pipeline cutting valve 13, and adjusting and controlling the flow rate of hot oxygen gas with the hot oxygen gas pipeline control valve 42. Step S1 involves adjusting the blowing parameters, which includes adjusting the flow rates of compressed air, hot oxygen gas, and nitrogen gas to desired values, and controlling the oxygen gas content in the total blowing rate of the mixed gas to be within the range of 21-25% during that period, wherein in this blowing mode, the blast furnace enters a shut-off state after at least one smelting cycle has elapsed, Step S2 involves re-air supplying, When restarting ventilation after a prolonged shutdown or shutdown due to abnormal furnace conditions, before restarting ventilation, ensure that the half of the tuyeres closest to the pig nozzle is open and the other half away from the pig nozzle is closed, restart ventilation is performed at half of the tuyeres, and during the restarting process, select the ventilation mode using a mixture of hot compressed air, hot oxygen gas, and hot nitrogen gas, that is, blow highly stable nitrogen gas through the system for 1 minute, blow in hot compressed air in step S1, blow in hot oxygen gas, and operate by adjusting the ventilation parameters according to the procedure, controlling the oxygen gas content in the overall ventilation volume during the restarting process to be within the range of 21-25%, and after restarting ventilation, perform step S2 to restore the furnace conditions using that ventilation method. When switching the fan mode after restoring the furnace conditions, Step S3 involves switching from a blowing mode using a mixture of hot compressed air, hot oxygen gas, and hot nitrogen gas to a blowing mode using a mixture of hot coal gas, hot oxygen gas, and highly stable nitrogen gas, specifically by stopping the injection of hot oxygen gas, opening the hot oxygen gas pipeline nitrogen gas injection valve 18, adjusting the hot oxygen gas pipeline control valve 42 to reduce the amount of hot oxygen gas injected until the flow rate of hot oxygen gas becomes 0, closing the hot oxygen gas pipeline cutting valve 12 and the hot oxygen gas pipeline cutting valve 13, opening the hot oxygen gas pipeline release valve 15 and the hot oxygen gas pipeline release valve 16, closing the hot oxygen gas pipeline nitrogen gas injection valve 18, and closing the hot oxygen gas pipeline blind plate valve 14. The process involves stopping the injection of hot compressed air, stopping the injection of hot oxygen gas, then opening the compressed air pipeline nitrogen gas injection valve 8 and adjusting the compressed air pipeline control valve 41 to reduce the amount of compressed air injected until the compressed air flow rate becomes 0, closing the compressed air pipeline cutting valve 2 and the compressed air pipeline cutting valve 3, opening the compressed air pipeline release valve 5 and the compressed air pipeline release valve 6, closing the compressed air pipeline nitrogen gas injection valve 8, and closing the compressed air pipeline blind plate valve 4. This involves blowing in cold oxygen gas, supplying cold oxygen gas 39 through the tuyeres of the blast furnace, adjusting the amount of cold oxygen gas injected, and controlling the oxygen content of the total airflow of the mixed gas to be within the range of 21-25% during that period. Under the condition that the oxygen content of the total airflow is controlled to be within the range of 21-25%, it is confirmed that the blast furnace is operating normally when the amount of cold oxygen gas injected is increased to its maximum. Injecting hot coal gas, checking that the mixed coal gas pipeline cut-off valves 27 and 28 are in the closed state, opening the mixed coal gas pipeline blind flange valve 31, opening the mixed coal gas pipeline nitrogen gas injection cut-off valve 30, closing the mixed coal gas pipeline vent valves 32 and 33, opening the mixed coal gas pipeline cut-off valves 27 and 28, adjusting the mixed coal gas pipeline regulating valve 43, gradually increasing the injection amount of the mixed coal gas until the operation and production requirements are met, and closing the mixed coal gas pipeline nitrogen gas injection cut-off valve 30 when the injection amount of the mixed coal gas exceeds 5000 m3 / h, including step S3, a blowing method for treating long-term blast interruption or abnormal furnace conditions in a hydrogen-enriched and carbon-circulating oxygen blast furnace.

Example

[0014] The following is an example of restoring the furnace condition according to the above method, taking the HY blast furnace of the Xinjiang Bayi Steel Low-Carbon Test Platform as the implementation object.

[0015] At 11:15 on May 25, 2023, the regular repair in the blast furnace working area of the hydrogen-enriched and carbon-circulating oxygen blast furnace project HY was completed. In this regular repair, mainly, the inspection items include the local replacement of the blowing device at the tuyere, the remanufacture of the main trough, the overall replacement of the mud gun, and the replacement of the slag washing duckbill. The repair from the start of blast interruption at 9:00 on May 24 to the start of blowing at 11:15 on May 25 took a total of 1575 minutes.

[0016] The charge structure at the time of blast interruption of the blast furnace on May 24 is as follows.

[0017]

Table 1

[0018]

Table 2

[0019] The re-blowing method in the blast furnace is as follows: A mixed gas system of nitrogen gas, cold oxygen gas, and hot coal gas is used for re-blowing, with all 14 tuyeres open and the airflow parameters during re-blowing set as follows.

[0020] [Table 3] The status of molten metal tapping at the furnace after blast furnace venting on May 25th at 11:50 is as follows:

[0021] [Table 4] Blowing began at 11:50 on May 25th. From 12:18, the stock rods were set to 1.42m on the south side and 1.24m on the north side. Without operating the stock lines, the blast furnace was judged to be hanging, and the hot air pressure was set to 155kpa, resulting in a pressure difference of 84kpa. At 14:27, a slip accident suddenly occurred, and the stock rods were changed from 1.42m to 2.47m on the south side and from 1.24m to 2.32m on the north side. The hot air pressure was set to 117kpa, resulting in a pressure difference of 31kpa.

[0022] Following the slip accident, the liquid level in the expansion tank of the blast furnace rapidly decreased, increasing the amount of softened water supplied. Simultaneously, inspection of the water flow trend in the small sleeves revealed leakage characteristics in small sleeves 2, 3, and 6, with a difference of 7 L / min between inflow and outflow. An inspection of the cooling water system at the blast furnace site confirmed leakage in large sleeves 4 and 5, and in small sleeves 2, 3, and 6, and the blast furnace was shut down at 20:05 on May 25th. After this restart, a total of 26 patches of charge were added.

[0023] At 20:05 on May 25th, the blast furnace was shut down, and the large sleeves for #4 and #5, and the small sleeves for #2, #3, #4, #5, and #6 were replaced. The amount of softened water supplied before the shutdown was 31.67 m3. At 13:40 on May 26th, the replacement of the blower that had been leaking at the tuyeres was completed, and the blast furnace was restarted. During this restart process, the parameters of the blast furnace charge charging system were as follows: Ore batch: 14.5t, Coke batch: 4.78t, Coke ratio: 515.3 kg / t, Load: 3.021, Charge charging mode: 2P 24.5° 6 rotations↓ 2K 24.5° 6 rotations↓ Stock line: 1.6m. The method of restarting the blast furnace was as follows. A blow-in type re-airing system using a mixed gas of nitrogen, cold oxygen, and hot coal gas is employed, with 11 tuyeres being used to blow air, and the air-blowing parameters during re-airing are set as follows.

[0024] [Table 5] After re-blowing, the pig nozzle was opened once around 15:00, and a small amount of red slag was ejected. Immediately after a large ejection occurred at the pig nozzle, the nozzle was closed. There were 11 tuyeres for blowing air, and tuyeres 3, 4, and 5 were blocked with a mud gun. After blowing air, the tuyeres operated normally, and the stock line operated slowly. At 15:07 on May 26, the injection of coke oven gas into the blast furnace began, and at 15:08, a small pipe appeared in the blast furnace, the top pressure rose to 184 kPa, and the top temperature rose to 135°C. After the appearance of the pipeline, the stock rod in the north suddenly increased from 1.94m to 4.08m, and the stock rod in the south increased from 2.24m to 3.86m. Immediately afterward, an abnormality was found in the difference between the inflow and outflow of the small sleeves 6, 7, 8, 9, and 11, and the liquid level in the expansion tank of the blast furnace rapidly decreased. When instructed to check the water condition and observe the tuyere, it was reported that the tuyere had turned completely black. On-site inspection revealed that there was water leakage in the small sleeves 6, 7, 8, 9, and 11, and the large sleeve 6. At 16:20, the blast furnace was shut down and the damaged blower was replaced. At the morning meeting at 8:18 on May 27, each department resolved to treat this incident as a furnace cooling accident. During the day shift on May 27, the furnace was operated with oxygen gas at tuyeres 1 and 14 (the small sleeves at 1, 2, 13, and 14 were replaced with small sleeves at both chambers), and an oxygen gas gun was installed in the pigshorn nozzle. At 20:25 on May 27, the blast furnace was re-blowed. The parameters of the blast furnace charge charging system during this re-blow were as follows: Ore batch: 12t, Coke batch: 5.3t, Coke ratio: 698kg / t, Load: 2.26, Charge charging mode: 2P 23.5° 6 rotations↓ 3K 23.5° 8 rotations↓ Stock line: 1.6m.

[0025] As a method of re-blowing in the blast furnace, a blow-in type re-blowing system using a mixed gas of nitrogen gas, hot oxygen gas, and hot compressed air is used. There are four tuyeres in this system, and air will be blown using tuyeres 1#, 2#, 13#, and 14#. The remaining tuyeres will be sealed with refractory bricks or cement to completely block out any excess nitrogen gas in the tuyeres. The pressure point (BP) will be set to 170 kPa, the air velocity to 200 m / s or more, the pressure difference to 140 kPa or less, and the oxygen gas content in the blown-in volume to 25% or less. The air-blowing parameters for this re-blowing system will be set as follows.

[0026] [Table 6] Around 3:20 AM on May 28th, an on-site inspection revealed a water leak in the anteroom of the 13# small sleeve. Water surface control was performed over an area of ​​7.5 m³, and maintenance was carried out on the tuyeres by passing nitrogen gas through them. The blast furnace condition gradually recovered. Around 6:00 PM on May 28th, tapping was resumed at the front of the furnace and the pit was opened, restoring normal tapping. Around 6:30 AM on May 29th, all tuyeres except for 8# and 9# were opened. Around 6:00 PM, cold oxygen gas was blown into the tuyeres of the blast furnace. Around 7:00 PM, decarbonized coal gas was sent to the blast furnace. Around 11:00 PM, coke oven gas was sent to the blast furnace. At this point, the handling of the blast furnace cooling accident was basically complete, so the operating parameters were gradually restored. By May 30th, the operating parameters and the hydrogen-enriched / carbon-recycling oxygen blast furnace had basically recovered to normal levels. The silicon level in the blast furnace has dropped to 0.74. This means that the response to the blast furnace accident has been completed.

Claims

1. A method for supplying air during prolonged periods of blast shutdown in a hydrogen-enriched, carbon-cycle type oxygen blast furnace, In switching the blowing mode before a long period of shutdown or in the event of abnormal furnace conditions in a hydrogen-enriched, carbon-cycle type oxygen blast furnace, The normal operating state of a hydrogen-enriched, carbon-cycle type oxygen blast furnace is a mode in which coal gas, oxygen gas, and highly stable nitrogen gas are mixed and blown into the furnace. This involves stopping the injection of coal gas and oxygen gas, controlling the theoretical combustion temperature to be within the range of 1900 to 2400°C before stopping the injection of coal gas, performing a depressurization operation by reducing the amount of coal gas and oxygen gas injected, and after stopping the injection of coal gas, controlling the oxygen gas content in the overall airflow to be 25% or less until the injection of oxygen gas is stopped, thereby performing an operation to reduce the amount of oxygen gas injected (S1). Specifically, This involves passing highly stable nitrogen gas through, opening the highly stable nitrogen gas control valve (44), opening the highly stable nitrogen gas cut-off valves (22, 23), and setting the flow rate of highly stable nitrogen gas to 5000 m³. ３ Controlling the flow rate to / h, stopping the injection of coal gas, 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 cutting valve (27), opening the mixed coal gas pipeline nitrogen blow cutting valve (30) and blowing for 1 minute, then closing the mixed coal gas pipeline cutting valve (28), opening the mixed coal gas pipeline release valve (32) and mixed coal gas pipeline release valve (33), closing the mixed coal gas pipeline nitrogen blow cutting valve (30), closing the mixed coal gas pipeline blind plate valve (31), stopping the injection of oxygen gas supplied from the oxygen pipeline (39), and injecting compressed air supplied from the compressed air supply pipeline (1), Confirm that the disconnect valve (2) and the compressed air pipeline disconnect valve (3) are closed, open the compressed air pipeline blind plate valve (4), close the compressed air pipeline release valve (5) and the compressed air pipeline release valve (6), open the compressed air pipeline disconnect valve (2) and the compressed air pipeline disconnect valve (3), and adjust and control the flow rate of compressed air with the compressed air pipeline control valve (41), and blow in oxygen gas supplied from the oxygen gas supply pipeline (11), confirm that the pipeline disconnect valve (12) and the pipeline disconnect valve (13) are closed, open the pipeline blind plate valve (14), close the pipeline release valve (15) and the pipeline release valve (16), open the pipeline disconnect valve (12) and the pipeline disconnect valve (13), and adjust and control the flow rate with the pipeline control valve (42), and, Step (S1) includes adjusting the airflow parameters, which involves adjusting the flow rates of compressed air, oxygen gas, and nitrogen gas to desired values, and controlling the oxygen gas content in the total airflow rate of the mixed gas to be within the range of 21-25% during that period. Step S2 is to re-blow air, When restarting ventilation after a long period of shutdown or shutdown due to abnormal furnace conditions, before restarting ventilation, it is confirmed that the half of the tuyeres closest to the pig nozzle is open and the other half away from the pig nozzle is closed, and ventilation is restarted at half of the tuyeres. During the restarting process, the ventilation mode is selected to use a mixture of compressed air supplied from the compressed air supply pipe (1), oxygen gas supplied from the oxygen gas supply pipe (11), and highly stable nitrogen gas. That is, the system is operated by blowing highly stable nitrogen gas for one minute, blowing compressed air in step S1, and blowing oxygen gas, adjusting the ventilation parameters in accordance with the procedure, controlling the oxygen gas content in the overall ventilation volume during the restarting process to be within the range of 21-25%, and after restarting ventilation, the furnace conditions are restored according to the ventilation method (S2). When switching the fan mode after restoring the furnace conditions, When the furnace conditions are restored, the furnace temperature is normal, tapping at the furnace is normal, 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 a blowing mode using a mixed gas of compressed air supplied from the compressed air supply pipeline (1), oxygen gas supplied from the oxygen gas supply pipeline (11), and highly stable nitrogen gas to a blowing mode using a mixed gas of coal gas, oxygen gas, and highly stable nitrogen gas (S3), specifically by stopping the blowing of oxygen gas supplied from the oxygen gas supply pipeline (11), and the nitrogen gas in the pipeline The blowing amount is reduced until the flow rate becomes 0 by opening the blowing valve (18) and adjusting the pipeline control valve (42), closing the pipeline cutting valve (12) and pipeline cutting valve (13), opening the pipeline release valve (15) and pipeline release valve (16), closing the pipeline nitrogen gas blowing valve (18), closing the pipeline blind plate valve (14), and stopping the blowing of compressed air supplied from the compressed air supply pipeline (1), and after stopping the blowing of oxygen gas, the compressed air pipeline nitrogen gas blowing valve (8) is opened and the compressed air pipeline control valve (41) is adjusted so that the flow rate of compressed air becomes 0. Until this is achieved, the amount of compressed air being blown in is reduced, the compressed air pipeline cutting valve (2) and the compressed air pipeline cutting valve (3) are closed, the compressed air pipeline release valve (5) and the compressed air pipeline release valve (6) are opened, the compressed air pipeline nitrogen gas blowing valve (8) is closed, and the compressed air pipeline blind plate valve (4) is closed, and oxygen gas supplied from the oxygen pipeline (39) is blown in, the oxygen gas is sent in through the tuyeres of the blast furnace, the amount of oxygen gas being blown in is adjusted, and during this period the oxygen gas content in the total airflow rate of the mixed gas is controlled to be within the range of 21-25%, and the total airflow rate Under the condition that the oxygen gas content is controlled to be within the range of 21-25%, when the amount of oxygen gas injected is increased to the maximum, it is confirmed that the blast furnace operation is normal, and coal gas supplied from the mixed coal gas pipeline (26) is injected, and it is confirmed that the mixed coal gas pipeline cutting valve (27) and the mixed coal gas cutting valve (28) are closed, the mixed coal gas pipeline blind plate valve (31) is opened, the mixed coal gas pipeline nitrogen gas blow cutting valve (30) is opened, and the mixed coal gas pipeline release valve (32) and the mixed coal gas pipeline release valve (33) are closed.By opening the mixed coal gas pipeline cutting valve (27) and the mixed coal gas cutting valve (28) and adjusting the mixed coal gas pipeline control valve (43), the amount of mixed coal gas injected is gradually increased until the operational and production requirements are met, and the amount of mixed coal gas injected is 5000 m. ３ A method for supplying air for a long period of time at rest in a hydrogen-enriched, carbon-cycle type oxygen blast furnace, characterized by comprising the step (S3) of closing a mixed coal gas pipeline nitrogen gas blowing cutting valve (30) after the rate exceeds / h.

2. A method for supplying air during a long period of shutdown in a hydrogen-enriched, carbon-recycling oxygen blast furnace according to claim 1, characterized in that chain protection is provided so that the pressure of highly stable nitrogen gas minus the pressure of compressed air > 0.05 MPa, otherwise the compressed air control valve and the cut-off valve are all set to automatically close in a chain.

3. A method for supplying air for a long period of time without air in a hydrogen-enriched, carbon-recycling oxygen blast furnace according to claim 1, characterized in that a chain protection is provided so that the pressure of the highly stable nitrogen gas and the pressure of the oxygen gas supplied from the oxygen gas supply pipeline (11) are > 0.05 MPa, otherwise the oxygen gas control valve and cut-off valve are all set to automatically close in a chain.

4. A method for supplying air for a long period of time at rest in a hydrogen-enriched, carbon-recycling oxygen blast furnace according to claim 1, characterized in that chain protection is provided so that the pressure of the highly stable nitrogen gas minus the pressure of the mixed coal gas is > 0.05 MPa, otherwise the mixed coal gas control valve and the cut-off valve are all set to automatically close in a chain.

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