Method for inhibiting knocking in blowing-out process of blast furnace empty stockline

Abstract

The invention discloses a method for inhibiting knocking in a blast furnace shutdown rapid stockline descending process, which comprises the following steps of: carrying out thermal washing and hearth activation operation on a wall body before the stockline descending of the blast furnace; after a stockline begins to descend, the air volume and the hot air temperature are controlled in a staged mode, the generated slag iron is discharged in a planned mode, so that a material layer on the upper portion of an air opening can be rapidly consumed, and the top temperature is combined to guide water drawing amount control, so that sticking substances on a wall body are reduced; in the whole blowing-out process, the working state that water is fully vaporized before falling to the material surface and free water does not fall on the material surface can be maintained, the use of large air quantity can be effectively maintained by utilizing the control points, the rapid falling of the material surface is realized, the time for falling the material surface is shortened, the knocking in the furnace is reduced, and the blowing-out safety and the working efficiency are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of blast furnaces, and in particular relates to a method for suppressing explosion during the shutdown process of an empty material line of a blast furnace. Background Art

[0002] During the operation of the blast furnace, the cooling wall or the refractory material of the furnace will gradually be damaged. When the damage reaches a certain extent, the blast furnace needs to be shut down for overhaul. During the shutdown process, stop loading the charge 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 furnace and discharged regularly. The space vacated after the slag iron is discharged further allows the upper materials to descend. 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 generated 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 take the method of pumping water on the furnace top and gradually reducing the air volume to avoid excessively high furnace top temperature and control 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. The wall-bonded materials or the overly thick slag skin will be impacted and fall during the material lowering process by the gas flow, which will also cause frequent fluctuations in the gas flow. The key points of this method are how to adjust the load, alkalinity and airflow of the charge to make the wall "clean" and the slag skin thickness within an appropriate range, determine the shutdown process in combination with top temperature monitoring, coordinate with the reduction of hot air temperature and air volume, and reasonably arrange the timing of iron tapping to suppress detonation. Summary of the invention

[0003] The purpose of the present invention is to provide a method for suppressing explosion during the shutdown process of an empty material line of a blast furnace, which has a fast material level lowering speed and 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 suppressing detonation during the shutdown process of a blast furnace empty material line, comprising the following steps:

[0006] 1) Active hearth and hot-washing furnace wall stage: Three days before shutdown, the average daily physical temperature of molten iron should be controlled to be >1500℃, the slag R should be reduced by 0.05-0.15 compared with normal smelting, and the daily coal ratio should be ≯150kg / t.

[0007] 2) After executing step 1) for 2 days, the temperature distribution of the furnace waist and the lower wall of the furnace body is inspected: the right-skewed distribution during normal production is required to be transformed into a normal distribution, and the average wall temperature is increased by more than 3°C; if the above effect is not achieved, the charging system is adjusted to increase the edge airflow index W value by 10%.

[0008] 2) Install a water pump on the top of the furnace for small wind breaks, which requires good atomization, uniform spray in the circumferential direction, and an hourly spray volume of more than 200t;

[0009] 3) Prepare 60 tons of coke diced with particle size less than 25 mm as cover coke;

[0010] 4) During the process of restoring the air volume after a short wind break, the oxygen volume is quickly restored according to the material discharge situation; the air volume is maintained above 12m of the material line> 85% of the full air volume, and the air volume is actively and gradually reduced when the material line is close to the lower part of the furnace body, so that 70% of the full air volume < 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 turned off 2-3m above the connection between the furnace body and the furnace waist. If the gas analysis O2> 2%, it is turned off in advance;

[0011] 5) The air temperature of the material-lowering line is controlled at 1000±20℃;

[0012] 6) During the material lowering process, the water pumping device on the furnace top is controlled 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. If the water volume is already at the maximum level, the air volume is reduced to make the bag inlet temperature <260°C and the furnace top temperature <350°C. It is also necessary to ensure that the bag temperature is >70°C and the furnace top temperature is >100°C. If the temperature is lower than the above values, the water pumping amount is reduced to prevent condensation in the bag and excessive water pumping causing water to fall on the material surface;

[0013] 7) The first iron is arranged to open the taphole when 20-30% of the total iron in the furnace is generated, and the first iron is arranged to produce 55-65% of the total iron in the furnace. If it is not completely produced, the taphole will be blocked; the second iron opening time is to open the taphole 1-1.5 hours after blocking, and the taphole will be blocked if all the iron is produced.

[0014] Furthermore, the air temperature of the material-lowering line is controlled at 1000°C.

[0015] Furthermore, in step 5), the furnace waist position is entered to actively reduce the hot air temperature by 100±10°C.

[0016] Furthermore, the first iron production accounts for 60% of the total furnace iron production.

[0017] Furthermore, when the ventilation starts, the air volume of the supply air is gradually increased to the air volume in the full wind state.

[0018] Furthermore, during the material surface descent, the probe monitors the actual position of the material surface to actively reduce the air volume to increase the safety factor. As the material surface descends, the air volume is actively reduced according to the top temperature and gas composition: the material line position is 17.26m, and the air volume is 6000m 3 / min, material line position 21.64m, air volume used is 70% of the maximum air volume.

[0019] Furthermore, after air supply, the whole furnace material can produce 1200t of iron; air supply for 1.5h, air volume 6000m 3 / min, total air volume 593Km 3 , the first tapping operation was carried out after the iron output was 343t, and the tapping was blocked when the total output of the first tapping was 800t; the second tapping was carried out 1h after the first tapping, and the air volume was >5200m 3 / min, and a total of 400t of iron was discharged in the second time; when the material line dropped to the center line of the tuyere for the third time, the iron mouth was opened after observing that part of the tuyere became dark. At this time, there was no molten iron, and mainly slag was discharged, which reduced the workload for subsequent furnace cleaning.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are:

[0021] The present invention performs heat washing and active furnace operation on the wall before the material lowering line of the blast furnace, and controls the air volume and hot air temperature in stages after the material lowering line is started, and utilizes the planned discharge of generated slag and iron to quickly consume the material layer above the tuyere, and combines the top temperature to guide the control of water injection volume, so that the adhesive on the wall is reduced and the air volume is matched with the water injection volume, so that the water injection volume can be fully vaporized before falling to the material surface during the entire shutdown process, and there will be no free water falling on the material surface. The above control points can effectively maintain the use of large air volume, realize rapid lowering of the material surface, reduce the time of lowering the material surface, reduce explosion in the furnace, and improve shutdown safety and work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings.

[0023] Figure 1 The histograms before and after furnace cleaning;

[0024] Figure 2 This is the probability diagram before and after furnace cleaning. DETAILED DESCRIPTION

[0025] A method for suppressing detonation during the shutdown of a blast furnace empty material line, specifically comprising:

[0026] Active hearth and hot-washing furnace wall stage: three days before shutdown, control the daily average physical temperature of molten iron to be >1500℃, reduce the slag R from 1.15 in the normal stage to 1.05, and the daily coal ratio is ≯150kg / t.

[0027] After the above steps are performed for 2 days, the temperature distribution of the cooling wall at the lower part of the furnace body, the furnace waist, and the furnace belly is detected to confirm the effect of the furnace washing. The following example uses the wall temperature at the furnace waist as an example: From the histogram below, it can be seen that the temperature distribution of the furnace waist wall before furnace washing is right-skewed, and there are many points with high temperatures that deviate from the main body. This is mainly due to the shedding of thick slag skin, which leads to high local temperatures. After furnace washing, the mean value of the wall temperature shows an obvious rightward trend, indicating that the wall temperature has been significantly improved. From the probability graph below, it can be seen that the mean value of the temperature distribution after furnace washing is 51.58°C, which is about 5°C higher than the mean value of the wall temperature before furnace washing, and the effect is obvious. The P value of the normal distribution test after furnace washing is greater than 0.05, which is a normal distribution, indicating that the phenomenon of higher frequency of points with higher wall temperature caused by the shedding of slag skin or adhesive before furnace washing has been significantly improved. The above data show that the furnace washing effect is good.

[0028] When the air supply starts to recover, the air volume is gradually increased to the air volume in the full air state. The full air state is the maximum air volume input in the normal production state, and the oxygen content in the high temperature air is also the maximum value in normal production. For example: 4150m 3 When the blast furnace is in full air and full oxygen state, the air volume is 6800m 3 / min, oxygen is 20000m 3 / h. Due to the large amount of wind oxygen and violent reaction, the material surface begins to drop rapidly, and the temperature of the gas escaping from the furnace top rises rapidly. The furnace top water supply device is gradually opened to spray cooling water. Start to monitor the furnace top temperature and bag inlet temperature. In this example, the bag temperature is <260℃ and the furnace top temperature is <350℃. When the actual temperature value detected exceeds 260℃ or T2>350℃, water is sprayed through the sprinkler device to cool down the 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 to increase the safety factor. As the material surface drops, the air supply volume is actively reduced according to the top temperature and gas composition: the material line position is 17.26m, and the air volume is 6000m 3 / min (77% of maximum air volume), the material line position is 21.64m, and the air volume is 70% of the maximum air volume.

[0029] After air supply, the whole furnace can produce 1200t of iron. Air supply for 1.5h, air volume 6000m 3 / min, total air volume 593Km 3 , the first tapping operation was carried out after the iron output was 343t, and the tapping was blocked when the total output of the first tapping was 800t. The second tapping was carried out 1h after the first tapping, and the air volume was >5200m 3 / min, the second iron output is about 400t iron. The third iron output is when the material line drops to the center line of the tuyere, and the tuyere is opened after the tuyere becomes dark. At this time, there is no molten iron, and the main output is slag, which reduces the workload for subsequent furnace cleaning.

[0030] After taking the above measures, no obvious detonation phenomenon occurred during the material lowering process.

[0031] 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 suppressing detonation during the shutdown of a blast furnace empty charge line, characterized in that: The steps include: 1) Active hearth and hot-wash furnace wall stage: Three days before the shutdown, control the daily average physical temperature of the molten iron to be greater than 1500℃, the slag R is reduced by 0.05-0.15 compared with normal smelting, and the daily coal ratio is ≯150kg / t. 2) Two days after performing step 1), perform a temperature distribution test on the furnace waist and lower wall of the furnace body: the right-skewed distribution during normal production must be transformed into a normal distribution, and the mean wall temperature must increase by at least 3°C. If this effect is not achieved, adjust the charging system to increase the edge airflow index W by 10%. 2) Install a water-spraying device on the top of the furnace during a small wind break, which requires good atomization, uniform spraying in the circumferential direction, and an hourly spraying volume of more than 200t; 3) Prepare 60t of coke dicing with a particle size of less than 25mm as cover coke; 4) During the process of restoring the air volume after a short break, the oxygen volume should be quickly restored according to the material discharge situation; the air volume should be maintained above 85% of the full air volume above 12m of the material line, and the air volume should be actively and gradually reduced when the material line approaches the lower part of the furnace body, so that 70% of the full air volume < air volume < 85% of the full air volume; the use of oxygen should be gradually reduced in proportion as the air volume is reduced, and the oxygen should be turned off 2-3m above the connection between the furnace body and the furnace waist. If the gas analysis shows O2>2%, it should be turned off in advance; 5) The air temperature of the material-lowering line is controlled at 1000±20℃; 6) During the material lowering process, the furnace top water pumping device is controlled 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 to ensure that the bag inlet temperature is less than 260°C and the furnace top temperature is less than 350°C. It is also necessary to ensure that the bag temperature is greater than 70°C and the furnace top temperature is greater than 100°C to prevent condensation on the bag and excessive watering that causes water to fall on the material surface; 7) The first iron is arranged to open the taphole when 20-30% of the total iron in the furnace is generated, and the first iron is 55-65% of the total iron in the furnace. If not all the iron is produced, the taphole will be blocked; the second iron opening time is 1-1.5 hours after the taphole is blocked, and the taphole will be opened to produce all the iron.

2. The method for suppressing detonation during the shutdown of a blast furnace empty charge line according to claim 1, characterized in that: At the beginning, the air temperature of the material-lowering line is controlled at 1000℃.

3. The method for suppressing detonation during the shutdown of a blast furnace empty charge line according to claim 1, characterized in that: In step 5), enter the furnace waist position and actively reduce the hot air temperature by 100±10°C.

4. The method for suppressing detonation during the shutdown of a blast furnace empty charge line according to claim 1, characterized in that: The first iron output is 60% of the total iron in the furnace.

5. The method for suppressing detonation during the shutdown of a blast furnace empty charge line according to claim 1, characterized in that: When re-airing begins, the air volume supplied is gradually increased to the air volume at full air state.

6. The method for suppressing detonation during the shutdown of a blast furnace empty charge line according to claim 1, characterized in that: During the material surface descent, the probe monitors the actual position of the material surface to actively reduce the air volume to increase the safety factor. As the material surface descends, the air volume is actively reduced according to the top temperature and gas composition: the material line position is 17.26m, and the air volume is 6000m 3 / min, the material line position is 21.64m, and the air volume is 70% of the maximum air volume.

7. The method for suppressing detonation during the shutdown of a blast furnace empty charge line according to claim 1, characterized in that: After air supply, the whole furnace material can produce 1200t of iron; air supply for 1.5h, air volume 6000m 3 / min, with a total air volume of 593 km 3 343t of iron has been generated and the first tapping operation is carried out. When the first tapping is 800t of iron, the tapping is blocked. The second tapping is carried out 1h after the first tapping. At this time, the air volume is greater than 5200m 3 / min, a total of 400t of iron was discharged in the second time; when the material line dropped to the center line of the tuyere for the third time, the iron mouth was opened after observing that part of 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.

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