Method for realizing quick empty stockline blowing-out of blast furnace

Abstract

The invention discloses a method for quickly lowering the charge level during blowing-out of an empty charge line of a blast furnace, which comprises the following steps of: mounting a high-flow atomizing water spraying device at the top of the blast furnace before damping down, and cooling high-temperature coal gas flow in the blowing-out process by using the water spraying device. Installing a deep stock rod with a burning loss prevention steel wire rope in the blast furnace; and charging coke with special particle size and moisture into the blast furnace before starting a blanking line. After small-damping-down air supply, the air supply volume is quickly recovered to the air volume in a full-air state; detecting the furnace top temperature, and adjusting the water fetching amount, the air supply amount, oxygen and the air temperature according to the furnace top temperature to enable the furnace top temperature to be less than or equal to 350 DEG C; the air supply volume is actively adjusted according to the charge level position measured by the stock rod and gas analysis components; and when the air supply volume reaches a set value, tapping operation is carried out. And when the set iron amount is reached, iron notch blocking operation is carried out, and iron notch spraying is not needed. The method has the characteristics of capability of keeping the material level to descend quickly, short blowing-out time, small slag iron retention amount and better safety.

Description

Technical Field

[0001] The invention relates to a method for realizing rapid shutdown of a blast furnace empty material line. Background Art

[0002] During the operation of the blast furnace, the cooling wall or the hearth refractory materials are damaged by the wear of materials, erosion of slag iron and thermal shock. When the cooling wall or the hearth refractory materials are damaged to a certain extent, the blast furnace needs to be shut down for overhaul. During the shutdown process, stop loading from the top, and use the hot air to continuously consume the materials in the blast furnace. The molten iron and slag generated after the consumption of the materials are gathered in the hearth and discharged regularly. After the materials in the blast furnace are continuously consumed, the inner wall of the blast furnace is exposed for easy maintenance. However, as the materials gradually decrease during the shutdown process, a large amount of high-temperature coal gas produced by the reaction of the lower hot air and coke will increase the temperature of the furnace top. Excessive furnace top temperature will burn the furnace top equipment and cause accidents. Therefore, it is necessary to adopt the method of pumping water on the furnace top and gradually reducing the air volume to avoid excessively high furnace top temperature and keep the gas composition within a safe range. However, a large amount of water pumping will cause some water to fail to vaporize in time. After falling on the material surface and reacting with the hot material, the volume will expand rapidly to produce a "detonation" phenomenon that endangers safety. Frequent and excessive reduction of air volume can reduce the furnace top temperature, but it will cause the travel of the material lowering line to be too long, which will also cause the water pumping to fail to vaporize in time, endangering safety. How to arrange the loading of shutdown materials to ensure that the slag iron has good fluidity and flows out of the furnace smoothly with the gradual reduction of gas utilization and hot air temperature during the shutdown process to reduce the retention amount in the furnace and reduce the workload of subsequent cleaning; how to determine the amount of water pumping through precise monitoring methods to ensure that the water pumped on the furnace top is vaporized in time before falling on the material surface, maintain a large air volume for a long time, and balance the amount of iron generated and the air volume, and arrange the iron-discharging operation at the key node time so that the slag iron accumulated in the furnace can flow out fully and quickly under the premise of higher air volume, so as to reduce the workload of subsequent cleaning of the furnace, which is the key part of this method. Summary of the invention

[0003] The purpose of the present invention is to provide a method for realizing the rapid shutdown of a blast furnace with an empty material line, which not only has a fast material level lowering speed but also has a high shutdown safety factor.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for realizing rapid shutdown of a blast furnace empty material line, comprising the following steps:

[0006] 1) Before the formal material lowering, the furnace top water pumping device is installed for air stop, and the probe device for replacing ordinary steel wire rope with heat-resistant steel wire rope is installed; two batches of small-size coke of 30t / batch are prepared, and the main belt is fully wetted with a water pipe without visible water, and the moisture content is controlled at 10-15%; small-size coke has a large specific surface area, which can fully absorb water during the water pumping process outside the furnace, and can fully exchange heat with the hot coal gas after entering the furnace, which can effectively reduce the top temperature; the loose and porous structure between coke and coke can prevent the volume expansion caused by the vaporization of free water from occurring in a limited space, thereby preventing the occurrence of "detonation" conditions; after the air supply and material lowering line begins, the addition During the air volume process, when the top temperature reaches 300°C, a batch of coke is placed in the blast furnace; during the process of gradually adding air, the second batch of coke is placed in when the top temperature rises to 300°C again, which is used to strengthen the heat exchange with the high-temperature coal gas, reduce the furnace top temperature, and reduce the amount of water pumping, and then the furnace top water pumping device is turned on to control the top temperature by pumping water; the bag filter temperature and the furnace top temperature are detected, and the water flow of the water pumping device is adjusted according to the bag filter temperature and the furnace top temperature, so that the bag inlet temperature is less than 260°C and the furnace top temperature is less than 350°C, and the bag temperature must be greater than 70°C and the furnace top temperature must be greater than 100°C to prevent condensation on the bag and excessive water pumping, so that free water falls on the material surface and contacts the hot material surface;

[0007] 2) In the process of restoring the air volume, the air volume and oxygen volume are quickly restored according to the material discharge situation, and the air volume and oxygen volume are fully restored within 40 minutes; the air volume is maintained above 12m of the material line> 85% of the full air volume, and when the material line is close to the lower part of the furnace body, the air volume is actively and gradually reduced to make 70%<air volume<85% of the full air volume; the use of oxygen is gradually reduced in proportion with the reduction of air volume, and the oxygen is stopped 2-3m above the connection between the furnace body and the furnace waist;

[0008] 3) The volume above the center line of the blast furnace tuyere is 3784m 3 , material line 1.5m, calculated according to compression rate 14%, total coke ratio of wind-off material 631kg / t, coke load 2.808t / t, slag ratio 417kg / t; theoretical iron content 1616t, slag content 677t; ore batch 82t, coke batch 29.2t, silica 2.2t, coke load 2.808t / t, wind-off after 33 batches before material drop; after air supply, add 2 batches of cover coke according to top temperature, coke batch 30t, totaling 60t, and no more material will be added afterwards;

[0009] 4) Air supply for 1.5h, air volume 6000m 3 / h, cumulative air volume 593Km 3 , the first iron tapping operation was carried out with an iron production of 343t, the first iron tapping took 1.5h, and a total of 674t of iron was produced during the period; the second iron tapping was carried out 1h after the first iron plugging, and the air volume was >5200m 3 / min, during the second iron discharge, 488t of iron was generated during 2h, and the outlet was blocked after the discharge time; when the third iron material line dropped to the center line of the tuyere, the tuyere was opened after the tuyere became dark. At this time, there was no molten iron, and the main discharge was slag, which reduced the workload for subsequent furnace cleaning.

[0010] Furthermore, in the step 2), if the gas analysis shows that O2>2%, the system can be shut down in advance.

[0011] Furthermore, in the step 2), the unsafe factors caused by the upward shift of the soft melting zone due to the addition of low-load wind-resting material are prevented.

[0012] Furthermore, the top temperature bandwidth is well controlled at 110°C and can achieve full gas recovery for power generation, contributing to extending the gas delivery time.

[0013] Furthermore, the TRT bag inlet temperature is controlled at 263℃-265℃, which provides a basis for the long-term stable operation of TRT.

[0014] Furthermore, the clean coal gas temperature after power generation can meet the clean coal gas network temperature requirement of <130°C, which can recycle a large amount of coal gas resources and reduce environmental pollution.

[0015] Furthermore, the material surface smoothly dropped below the tuyere, which greatly reduced the amount of furnace cleaning and the amount of water pumped was reduced by 140 tons compared with the same-level blast furnace.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are:

[0017] The present invention adjusts the air supply volume according to the actual position of the material surface and the average of the highest and lowest points of the top temperature and the difference between the highest and lowest points by setting the air supply volume at full wind state when the blast furnace starts to be supplied with air. This allows the working state in which the water volume is fully vaporized before falling on the material surface and no free water falls on the material surface during the entire shutdown process. The above control points can effectively maintain the use of large air volume, realize rapid lowering of the material surface, reduce the time for lowering the material surface, reduce explosions in the furnace, and improve shutdown safety and work efficiency. After using this method, the top temperature bandwidth is well controlled (controlled at 110°C) and the whole process of gas recovery for power generation can be realized, which contributes to extending the gas supply time. The TRT bag inlet temperature is controlled at 263°C.

[0018] -265℃, which provides a basis for the long-term stable operation of TRT. The clean coal gas temperature after power generation can meet the temperature requirements of the clean coal gas pipeline network (<130℃), which can recycle a large amount of coal gas resources and reduce environmental pollution. The material surface can smoothly drop below the tuyere, which greatly reduces the amount of furnace cleaning and the amount of water pumping is reduced by about 140 tons compared with the same-level blast furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] Figure 1 A schematic diagram of a blast furnace of an embodiment;

[0021] Explanation of the accompanying reference numerals: 1. feeding device; 2. water pumping device; 3. ore layer; 4. coke layer; 5. furnace throat; 6. furnace body; 7. furnace waist; 8. furnace belly; 9. furnace cylinder; 10. iron outlet; 11. molten iron; 12. slag; 13. hot air surrounding pipe; 14. tuyere; 15. gas pipeline. DETAILED DESCRIPTION

[0022] In order to make the technical problem solved by the present invention, the technical solution adopted and the technical effect achieved more clearly, the technical solution of the present invention is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0023] Reference Figure 1 As shown, the present invention provides a method for rapidly lowering the material level of a blast furnace during shutdown, which is applied to the shutdown of the blast furnace. The method comprises:

[0024] A water pumping device 2 with a large water pumping volume and good atomization effect is set on the top of the blast furnace. The cooling water is atomized by the water pumping device 2 and then sprayed to the furnace throat. A gas pipeline 15 is provided on the top of the blast furnace, and the rear end of the gas pipeline is connected to the bag filter. A probe with a high temperature resistant chain is installed in the blast furnace, and the probe is used to detect the position of the material surface. Air is supplied to the blast furnace through the air port 14, and the air supply volume is the air volume in the full wind state. The outlet temperature of the bag filter and the furnace top gas is detected, and the flow rate of the water pumping device 2 is adjusted according to the bag filter temperature and the furnace top gas outlet temperature, so that the bag filter temperature is T1; the air supply volume is adjusted according to the material surface position, and the gas outlet temperature T2 and the bag filter temperature T1 meet the requirements at the same time (100℃<T2<350℃, 70℃<T1<260℃);

[0025] Main process: The blast furnace ironmaking process is to provide high-temperature coal gas through the reaction of hot air and coke to reduce and melt the ore to generate molten iron 11. The blast furnace is divided into five areas from top to bottom, and the five areas are respectively the throat 5, the furnace body 6, the furnace waist 7, the furnace belly 8 and the furnace hearth 9. The smelting material is unloaded from the feeding device 1 located at the top of the blast furnace, wherein the iron ore and coke exist in the inner cavity of the blast furnace in the form of an ore layer 3 and a coke layer 4 in the blast furnace, respectively. An annular hot air surrounding pipe 13 is arranged at the position of the furnace belly 8 of the blast furnace. The hot air surrounding pipe 13 is used to transport high-temperature air. Along the direction of the hot air surrounding pipe, a plurality of tuyere 14 are arranged. The tuyere 14 is connected to the inside of the blast furnace, and the high-temperature air participating in the reaction is input into the blast furnace through the tuyere 14. Under the action of the high-temperature coal gas generated by the combustion of coke and air, the ore layer and the coke layer in the furnace belly 8 and the furnace waist 7 melt to form molten iron 11 and slag 12, which are deposited in the furnace and discharged through the iron outlet 10. As the ore and coke continue to burn and melt, the ore and coke located at the top move downward one after another. The coke layer at the top is the material surface (covering coke). During the process of the material surface descending, due to the continuous reduction of ore and coke in the furnace, the gas temperature and gas composition rising to the material surface undergo significant changes. If effective control is not carried out, it is easy to cause harmful phenomena such as burning of furnace top equipment and coal gas explosion. In this embodiment, a sprinkler 2 is arranged on the top of the blast furnace to spray atomized cooling water into the blast furnace to cool down the blast furnace gas escaping from the material surface, so as to avoid the burning of the furnace top charging equipment caused by excessive gas temperature, and to avoid excessive cooling water entering the furnace and falling on the material surface and rapidly vaporizing with the hot material surface in a short time to produce "detonation" and endanger the safety of the equipment. At the same time, the matching of the water volume and the air volume is controlled so that the temperature of the blast furnace gas after entering the bag filter will not be too high to burn the bag, nor will it be too low to cause condensation on the bag. A probe is installed in the furnace throat 5 to measure the position of the material surface. The measuring range of the probe can be extended to the corresponding position of the tuyere. The number of probes is two, which are used as spares to prevent the lack of monitoring equipment for the depth of the material surface after the probe chain is damaged. A pressure detection device, a temperature detection device, and a gas extraction device are installed in the furnace top gas pipeline 15 to monitor the occurrence of the "detonation" phenomenon and the "uniformity of gas temperature in the circumferential direction of the blast furnace", and to extract the gas composition for analysis. After the equipment is installed, re-airing begins, that is, high-temperature air is input into the blast furnace through the tuyere. After the high-temperature air enters the furnace belly 8, it mixes with the coke and burns. After a series of chemical reactions, the iron ore layer and the coke layer melt to form molten iron 11 and slag 12, which are discharged through the iron outlet 10. When re-airing begins, the air volume is gradually increased from zero to the air volume in the full air state. The full air state is the maximum air volume input during normal production, and the oxygen content in the high-temperature air is also the maximum value during normal production. For example: the capacity is 4150m 3 When the blast furnace is in full air and full oxygen state, the input air volume is 6800m 3 / min, oxygen input is 20000m3 / h. Due to the large amount of wind oxygen and the violent reaction, the material surface begins to drop rapidly, and the temperature of the coal gas escaping from the furnace top rises rapidly. At this time, small-particle wet coke is loaded to enhance the heat exchange effect between the moisture in the coke covering the material surface and the high-temperature coal gas. Gradually open the furnace top water pumping device to spray cooling water. Start monitoring T1 and T2. In this example, 70℃<T1<260℃ and 100℃<T2<350℃. When the actual temperature value detected exceeds 260℃ or T2>350℃, water is sprayed through the sprinkler 2 to cool down the coal gas temperature and avoid burning of the bag filter or furnace top equipment. During the process of the material surface falling, the probe monitors the actual position of the material surface to actively reduce the air volume in accordance with the smelting conditions to increase the safety factor. As the material surface drops, the air supply volume and oxygen volume are actively reduced according to the top temperature and coal gas composition. At the same time, when the charge level of the blast furnace drops to about 2m above the furnace waist, the soft melting zone has begun to disappear, the escape rate of high-temperature coal gas has significantly accelerated, and the instability of the charge level has gradually increased. At this time, stop adding oxygen. 3 Take the blast furnace of as an example, the volume above the center line of the blast furnace tuyere is 3784m3, the material line is 1.5m, and it is calculated according to the compression rate of 14%. The total coke ratio of the off-air material is 631kg / t, the coke load is 2.808t / t, and the slag ratio is 417kg / t; the theoretical iron volume is 1616t, and the slag volume is 677t. The ore batch is 82t, the coke batch is 29.2t, the silica is 2.2t, the coke load is 2.808t / t, and 33 batches are loaded, and then the wind is stopped. After the installation of the probe with high-temperature resistant chain and the large water pumping device on the furnace top, the air is supplied, and 2 batches of cover coke are loaded, the coke batch is 30t, and the total is 60t. No more material will be added after that. When the air supply starts, it is in full air and full oxygen state, with an air volume of 6800m 3 / min, oxygen input 20000m 3 / h. When the probe depth is less than 12m, the air volume is maintained at 6000m 3 / min or more, oxygen input is 10000m 3 / h or more. When the depth of the probe is 17m, the material surface is located at the lower part of the furnace body close to the furnace waist, stop adding oxygen, and reduce the air volume. During the process of reducing the air volume, for every 100m3 / min reduction in the air volume, the furnace top pressure decreases by 5kpa and the overall use level of the furnace top pressure is increased by 5Kpa compared with the normal furnace condition. When the material line drops to more than 12m, the air volume> 6000m 3 / min, 17.26m, 77% of the maximum air volume, 21.64m, the air volume is used to 70% of the maximum air volume. When the cumulative air volume reaches 770,000m 3 At this time, the blast furnace organizes the first iron tapping, and 1.5 hours after the first iron tapping, the blast furnace organizes the second iron tapping.

[0026] Implementation effect:

[0027] After taking the measures involved in this method, the blast furnace material line was smoothly lowered to below the tuyere. The amount of water pumped during the entire shutdown process was 2,362 tons, while the amount of water pumped for a blast furnace of the same level was more than 2,500 tons, saving water resources and increasing the calorific value of coal gas. The same level blast furnace adopts a coke load of 2.5, which is 2.64 in this case. A higher coke load can speed up the process of lowering the material line, and the furnace temperature is appropriate, the slag and iron fluidity is good, and the slag and iron are fully discharged. In this case, the difference between the actual iron output and the theoretical iron output is less than 5%, while the difference between the actual iron output and the theoretical iron output of the same level blast furnace is 8.8%, and there is no large explosion during the whole process;

[0028] The oxygen usage time of the same level blast furnace is less than 3 hours. In this case, the oxygen usage time is more than 4 hours, which greatly speeds up the process of lowering the material line. The material line of the same level blast furnace is less than 7m, and the air volume control is more than 6000m 3 / min, in this case, the material line is less than 12m, and the air volume control is more than 6000m 3 / min. The cover coke of the same level blast furnace is 114-180 tons. In this case, the amount of cover coke is greatly reduced to 60 tons. Because the air volume required to consume the cover coke is large, reducing the cover coke also greatly speeds up the process of lowering the material line. The material line of the same level blast furnace can only be lowered to the position above the tuyere in about 22 hours and 30 minutes. In this case, it has been lowered to below the tuyere, which greatly reduces the amount of furnace cleaning.

[0029] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for realizing rapid shutdown of a blast furnace emptying line, characterized in that: The steps include: 1) Before the formal material lowering, the furnace top water pumping device is installed for air stop, and the probe device for replacing ordinary steel wire rope with heat-resistant steel wire rope is installed; two batches of small-size coke of 30t / batch are prepared, and the main belt is fully wetted with a water pipe without visible water, and the moisture content is controlled at 10-15%; small-size coke has a large specific surface area, which can fully absorb water during the water pumping process outside the furnace, and can fully exchange heat with the hot coal gas after entering the furnace, which can effectively reduce the top temperature; the loose and porous structure between coke and coke can prevent the volume expansion caused by the vaporization of free water from occurring in a limited space, thereby preventing the occurrence of "detonation" conditions; after the air supply and material lowering line begins, the addition During the air volume process, when the top temperature reaches 300°C, a batch of coke is placed in the blast furnace; during the process of gradually adding air, the second batch of coke is placed in when the top temperature rises to 300°C again, which is used to strengthen the heat exchange with the high-temperature coal gas, reduce the furnace top temperature, and reduce the amount of water pumping, and then the furnace top water pumping device is turned on to control the top temperature by pumping water; the bag filter temperature and the furnace top temperature are detected, and the water flow of the water pumping device is adjusted according to the bag filter temperature and the furnace top temperature, so that the bag inlet temperature is less than 260°C and the furnace top temperature is less than 350°C, and the bag temperature must be greater than 70°C and the furnace top temperature must be greater than 100°C to prevent condensation on the bag and excessive water pumping, so that free water falls on the material surface and contacts the hot material surface; 2) In the process of restoring the air volume, the air volume and oxygen volume are quickly restored according to the material discharge situation, and the air volume and oxygen volume are fully restored within 40 minutes; the air volume is maintained above 12m of the material line> 85% of the full air volume, and when the material line is close to the lower part of the furnace body, the air volume is actively and gradually reduced to make 70%<air volume<85% of the full air volume; the use of oxygen is gradually reduced in proportion with the reduction of air volume, and the oxygen is stopped 2-3m above the connection between the furnace body and the furnace waist; 3) The volume above the center line of the blast furnace tuyere is 3784m 3 , material line 1.5m, calculated according to compression rate 14%, total coke ratio of wind-off material 631kg / t, coke load 2.808t / t, slag ratio 417kg / t; theoretical iron content 1616t, slag content 677t; ore batch 82t, coke batch 29.2t, silica 2.2t, coke load 2.808t / t, wind-off after 33 batches before material drop; after air supply, add 2 batches of cover coke according to top temperature, coke batch 30t, totaling 60t, and no more material will be added afterwards; 4) Air supply for 1.5h, air volume 6000m 3 / h, cumulative air volume 593Km 3 , the first iron tapping operation was carried out with an iron production of 343t, the first iron tapping took 1.5h, and a total of 674t of iron was produced during the period; the second iron tapping was carried out 1h after the first iron plugging, and the air volume was >5200m 3 / min, during the second iron discharge, 488t of iron was generated during 2h, and the outlet was blocked after the discharge time; when the third iron material line dropped to the center line of the tuyere, the tuyere was opened after the tuyere became dark. At this time, there was no molten iron, and the main discharge was slag, which reduced the workload for subsequent furnace cleaning.

2. The method for realizing rapid shutdown of a blast furnace emptying line according to claim 1, characterized in that: In the step 2), if the gas analysis shows that O2>2%, the system can be shut down in advance.

3. The method for realizing rapid shutdown of a blast furnace emptying line according to claim 1, characterized in that: In the step 2), the addition of low-load wind-resting material is prevented from causing the soft melting zone to move upward, thereby preventing unsafe factors.

4. The method for realizing rapid shutdown of a blast furnace emptying line according to claim 1, characterized in that: The top temperature bandwidth is well controlled at 110℃ and can achieve full gas recovery for power generation, which contributes to extending the gas delivery time.

5. The method for realizing rapid shutdown of a blast furnace emptying line according to claim 1, characterized in that: The inlet temperature of TRT bag is controlled at 263℃-265℃, which provides a basis for the long-term stable operation of TRT.

6. The method for realizing rapid shutdown of a blast furnace emptying line according to claim 1, characterized in that: The clean gas temperature after power generation can meet the clean gas pipeline temperature requirement of <130°C, which can recycle a large amount of gas resources and reduce environmental pollution.

7. The method for realizing rapid shutdown of a blast furnace emptying line according to claim 1, characterized in that: The material surface smoothly dropped below the tuyere, which greatly reduced the amount of furnace cleaning and the amount of water pumped was reduced by 140 tons compared with the same-level blast furnace.

Images