Method for rapidly and safely carrying out furnace top ignition after damping down of blast furnace

Abstract

The invention relates to the technical field of ironmaking processes, in particular to a method for rapidly and safely carrying out furnace top ignition after damping down of a blast furnace. The method comprises the following steps: before damping down, adjusting a stockline to be 0.5-1.0 m lower than a normal stockline; the furnace top temperature is controlled to be 200-350 DEG C; checking that the cooling equipment has no water leakage; closing a cloth bag glasses valve after damping down, standing for 10-15 minutes, then opening a backflow valve to flow back for 5-10 minutes, and fully opening a DN600 ignition manhole; an ignition gun is ignited, and flame is adjusted to be light blue; after the steam and the nitrogen are closed, an ignition gun extends into the furnace to ignite residual gas; and starting maintenance and continuously monitoring after the flame is stable. According to the method, by precisely regulating and controlling the stock line, the top temperature and the operation time sequence, on the premise that safety is guaranteed, the ignition operation duration is shortened to 2-2.5 hours from traditional 3-4 hours, time is bought for furnace top overhaul and blast furnace recovery, and the overhaul efficiency and production continuity are improved.

Description

Technical Field

[0001] This invention relates to the field of ironmaking technology, and in particular to a method for rapidly and safely igniting the furnace top after a blast furnace shutdown. Background Technology

[0002] After a blast furnace is shut down, some of the residual gas inside the furnace will be released into the air through the vent valve at the top of the furnace, the gravity dust collector, or the cyclone dust collector vent valve. A large amount of gas will also overflow from the manholes in various locations. At the top of the blast furnace, under the action of the residual pressure inside the furnace, the gas inside the furnace will overflow from the open manholes at the top of the furnace and the inspection holes of the chute. The purpose of igniting the top of the furnace is to ignite the residual gas escaping from the burden surface at the furnace throat, so that the gas generated inside the furnace during the shutdown period is in a state of combustion. If ignition is not carried out, the overflowing gas will spread everywhere, which will threaten the work safety of the surrounding maintenance personnel and damage the surrounding environment. Even if the furnace top equipment is not maintained and no personnel are arranged to work, long-term steam supply will accumulate a lot of moisture, which will adversely affect the blasting operation. Long-term nitrogen supply is also very uneconomical. Therefore, igniting the top of the furnace during shutdown is an economical and safe measure. Currently, after a shutdown, the gas system must first be shut off and purged, which usually takes 2 to 4 hours. Then, the tuyeres are sealed and the furnace top is ignited. Because the gas treatment takes a long time in the early stage, the furnace top temperature drops significantly, and the amount of gas generated in the furnace gradually decreases over time, which may make it difficult to ignite, thus extending the shutdown time. Summary of the Invention

[0003] To address the technical problem of long ignition time after blast furnace shutdown in existing technologies, this invention provides a method for rapid and safe ignition of the furnace top after blast furnace shutdown.

[0004] Therefore, the present invention provides the following technical solution:

[0005] A method for rapidly and safely igniting the furnace top after a blast furnace shutdown includes the following steps: S1. Before shutting down the blast furnace, adjust the blast furnace charge line to be 0.5 to 1.0 meters lower than the normal charge line under the current smelting conditions; S2. Control the furnace top temperature between 200 and 350°C by adjusting the opening of the furnace top vent valve, shutting off the furnace top cooling equipment, or taking measures such as covering the furnace top with insulation layer. S3. Inspect all cooling equipment in the blast furnace to ensure there are no leaks. If any cooling equipment is found to be leaking, stop the water supply to that cooling equipment. S4. After the blast furnace is shut down, close the bag filter valve. After shutting down for 10 to 15 minutes, open the backflow valve and backflow for 5 to 10 minutes. S5. Adjust the opening of the DN600 ignition manhole on the furnace top to 100%; S6. Place the gas ignition source at the ignition port of the ignition gun, open the gas valve integrated into the ignition gun and ignite the gas, increasing the gas flow until a flame-spitting sound is produced; S7. Close the steam delivery valve and nitrogen delivery valve at the top of the furnace, start the ignition gun and insert it into the furnace so that the top of the ignition gun flame contacts the material surface and ignites the residual gas in the furnace. S8. Observe the flame status inside the furnace. After the flame is burning steadily without flickering or going out, start the furnace top maintenance operation. During the operation, observe the flame burning status in real time. If the flame goes out, immediately stop all operations on the furnace top and tuyeres platform, and resume operations after re-ignition.

[0006] Furthermore, after igniting the gas in step S6, the external compressed air valve and the external oxygen valve connected to the ignition gun are opened in sequence. The compressed air flow and oxygen flow are adjusted through each valve so that the flame of the ignition gun is light blue, sprays continuously without interruption, and is without shaking.

[0007] Furthermore, in step S7, if the residual gas in the furnace is difficult to ignite and white smoke is observed accompanying the escaping gas, it is confirmed that the steam at the top of the furnace, the nitrogen in the nitrogen protection system of the top of the furnace camera, and the nitrogen in the pressure-holding system of the airtight box have been completely shut off. At the same time, the static pressure backflushing system of the furnace body is switched to manual mode and shut off, and the ignition operation is performed again.

[0008] Further, in step S8, the flame state inside the furnace is observed. If the flame state is unstable and flickers, the DN600 ignition manhole on the other side of the furnace top is opened. If the flame state is still unstable, the inspection hole of the furnace top chute is opened.

[0009] Furthermore, after observing that the flame state inside the furnace has stabilized in step S8, all direct-blown pipes connected to the blast furnace are disassembled.

[0010] Advantages and positive effects of the present invention: Compared to the traditional method with an operation time of 3 to 4 hours, this method can reduce the furnace top ignition operation to 2 to 2.5 hours while ensuring safety. This saves valuable time for furnace top maintenance and subsequent blast furnace smelting, significantly improving blast furnace maintenance efficiency and production continuity.

[0011] By adjusting the material line position, adjusting the temperature of the top temperature zone, and checking for leaks in the cooling equipment, the residual gas in the furnace is quickly and stably ignited, avoiding safety risks such as gas spillage, detonation, or ignition failure, and ensuring the safety of maintenance personnel and the surrounding environment.

[0012] It can be achieved without complex equipment modifications, relying on the existing blast furnace system, and takes into account safety, efficiency and economy. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 The flowchart illustrates a method for rapidly and safely igniting the furnace top after a blast furnace shutdown, as provided by this invention. Detailed Implementation

[0015] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0016] This invention provides a method for rapid and safe ignition of the furnace top after a blast furnace shutdown, such as... Figure 1 As shown, it includes the following steps: S1. Before shutting down the blast furnace, adjust the blast furnace charge line to be 0.5 to 1.0 meters lower than the normal charge line under the current smelting conditions. The charge line height determines the volume of the furnace top cavity, which in turn affects the amount of gas accumulated and the air mixing ratio. When it is 0.5 to 1.0 meters lower than the normal charge line, the furnace top cavity is of a suitable size, which can accumulate enough gas to meet the ignition requirements, without the formation of an explosive gas mixture due to excessive space. The furnace top temperature remains stable, and the problem of low furnace top temperature caused by excessively high charge lines can be avoided.

[0017] S2. The furnace top temperature can be controlled between 200 and 350°C by adjusting the opening of the furnace top vent valve, shutting off the furnace top cooling equipment, or taking measures such as covering the furnace top with insulation. The ignition temperature of coal gas is about 600°C, but in the high-temperature environment of 200-350°C, the activity of coal gas molecules is enhanced, the ignition temperature threshold is lowered, and with the residual pressure in the furnace and an appropriate amount of air, spontaneous combustion can be achieved. If the top temperature is below 200°C, the activity of coal gas molecules is insufficient and it is difficult to ignite. If the top temperature is above 350°C, the excessive temperature will directly burn the furnace top lining plate, valves and other equipment, and may also cause the vent pipe to catch fire, or cause the vent valve to deform due to high temperature and fail to close tightly, resulting in coal gas leakage.

[0018] S3. Inspect all cooling equipment in the blast furnace to ensure there are no leaks. If any leaks are found, stop supplying water to that cooling equipment; otherwise, the gas will contain a large amount of [unspecified substance]. And thus an explosion occurred.

[0019] S4. After the blast furnace is shut down, close the bag filter valve to cut off the connection between the furnace top gas and the subsequent pipeline network to prevent gas overflow or air backflow into the pipeline network; shut down for 10 to 15 minutes to allow the pressure inside the furnace to decay naturally, avoiding a sudden drop in pressure that could cause system instability. Then open the backflow valve and backflow for 5 to 10 minutes to remove residual inert gas and some low-concentration gas from the furnace and increase the concentration of the remaining gas.

[0020] S5. Adjust the opening of the DN600 ignition manhole on the furnace top to 100%; when opening the ignition manhole, the operator must not stand in front of the manhole to prevent the high-temperature gas from blowing and burning the operator. At the same time, the operator must stand upwind to prevent gas poisoning.

[0021] S6. Place the gas ignition source at the ignition port of the ignition gun, open the gas valve integrated into the ignition gun and ignite the gas, increase the gas volume until a flame is produced, and then open the external compressed air valve and external oxygen valve connected to the ignition gun in sequence. Adjust the compressed air flow and oxygen flow through each valve to make the ignition gun flame light blue, spray continuously without interruption, and without shaking.

[0022] S7. Close the steam and nitrogen supply valves at the top of the furnace to prevent the inert gas from diluting the coal gas concentration. Start the ignition gun and insert it into the furnace so that the top of the ignition gun flame contacts the material surface to ignite the residual coal gas in the furnace. If the residual coal gas in the furnace is difficult to ignite and white smoke is observed accompanying the escaping coal gas, confirm that the steam at the top of the furnace, the nitrogen in the nitrogen protection system of the top of the furnace camera, and the nitrogen in the pressure-holding gas box have been completely shut off. At the same time, switch the static pressure backflushing system of the furnace body to manual mode and shut it off, and re-execute the ignition operation.

[0023] S8. Observe the flame status inside the furnace. Once the flame is burning steadily without flickering or extinguishing, start the furnace top maintenance work. During the operation, observe the flame status in real time. If the flame goes out, immediately stop all work on the furnace top and tuyeres platform, and restart the ignition before resuming work. If the flame status is unstable, flickering and dimming, open the DN600 ignition manhole on the other side of the furnace top. If the flame status is still unstable, open the furnace top chute maintenance hole.

[0024] After observing that the flame inside the furnace is stable, all direct-blown pipes connected to the blast furnace are disassembled to prevent air from entering the blast furnace and burning the coke in the lower part of the blast furnace, which would increase the amount of gas produced, causing the flame to be too large and affecting subsequent maintenance operations. At the same time, it can also reduce heat loss and lay the foundation for the rapid recovery of the blast furnace.

[0025] Maintenance work can be started quickly after ignition without any extra waiting time; if the flame goes out, it can be detected in time and the work can be resumed after re-ignition, which not only ensures the safety of personnel but also avoids maintenance delays; the overall ignition operation time is reduced to 2 to 2.5 hours, saving 1 to 2 hours compared with traditional methods, thus gaining valuable time for furnace top maintenance and blast furnace recovery.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for rapidly and safely igniting the furnace top after a blast furnace shutdown, characterized in that, Includes the following steps: S1. Before shutting down the blast furnace, adjust the blast furnace charge line to be 0.5 to 1.0 meters lower than the normal charge line under the current smelting conditions; S2. Control the furnace top temperature between 200 and 350°C by adjusting the opening of the furnace top vent valve, shutting off the furnace top cooling equipment, or taking measures such as covering the furnace top with insulation layer. S3. Inspect all cooling equipment in the blast furnace to ensure there are no leaks. If any cooling equipment is found to be leaking, stop the water supply to that cooling equipment. S4. After the blast furnace is shut down, close the bag filter valve. After shutting down for 10 to 15 minutes, open the backflow valve and backflow for 5 to 10 minutes. S5. Adjust the opening of the DN600 ignition manhole on the furnace top to 100%; S6. Place the gas ignition source at the ignition port of the ignition gun, open the gas valve integrated into the ignition gun and ignite the gas, increasing the gas flow until a flame-spitting sound is produced. S7. Close the steam delivery valve and nitrogen delivery valve at the top of the furnace, start the ignition gun and insert it into the furnace so that the top of the ignition gun flame contacts the material surface and ignites the residual gas in the furnace. S8. Observe the flame status inside the furnace. After the flame is burning steadily without flickering or going out, start the furnace top maintenance operation. During the operation, observe the flame burning status in real time. If the flame goes out, immediately stop all operations on the furnace top and tuyeres platform, and resume operations after re-ignition.

2. The method for rapid and safe ignition of a blast furnace after shutdown according to claim 1, characterized in that, After igniting the gas in step S6, the external compressed air valve and the external oxygen valve connected to the ignition gun are opened in sequence. The compressed air flow and oxygen flow are adjusted through each valve to make the ignition gun flame light blue, spray continuously without interruption, and without shaking.

3. The method for rapid and safe ignition of a blast furnace after shutdown according to claim 1, characterized in that, In step S7, if the residual gas in the furnace is difficult to ignite and white smoke is observed accompanying the escaping gas, it is confirmed that the steam at the top of the furnace, the nitrogen in the nitrogen protection system of the top of the furnace camera, and the nitrogen in the pressure-holding gas in the airtight box have been completely shut off. At the same time, the static pressure backflush system of the furnace body is switched to manual mode and shut off, and the ignition operation is performed again.

4. The method for rapid and safe ignition of a blast furnace after shutdown according to claim 1, characterized in that, In step S8, observe the flame state inside the furnace. If the flame state is unstable and flickers, open the DN600 ignition manhole on the other side of the furnace top. If the flame state is still unstable, open the inspection hole of the furnace top chute.

5. The method for rapid and safe ignition of a blast furnace after shutdown according to claim 1, characterized in that, After observing that the flame state inside the furnace has stabilized in step S8, all direct-blown pipes connected to the blast furnace are disassembled.

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