Method for fast repairing the profile of a cooling plate blast furnace in the post-operation period of the furnace

Abstract

The present application belongs to the technical field of steel metallurgy, and particularly relates to a method for quickly repairing the furnace type of a cooling plate blast furnace in the later stage of the furnace campaign, comprising the following contents: (1) shortening the maintenance period: the maintenance period is shortened from the normal 4-5 months to 2-3 months; (2) furnace shell hole: taking advantage of the opportunity of the regular inspection, a grouting hole is arranged at the position where the cooling shield cracks and the furnace shell cracks; (3) dredging the grouting hole: after the ball valve of the grouting hole is removed, the electric hammer is used to dredge the residual refractory or slag shell in the furnace; (4) grouting and pressing into the material: taking advantage of the opportunity of the regular inspection, the prepared hard pressing material is pressed into the furnace through the new grouting hole and the old grouting hole by using the grouting machine; (5) controlling the airflow: after the air supply is maintained, the charging system is optimized, and the platform of the ore and coke is widened at the same time; (6) extending the maintenance time: the maintenance time is extended to more than 28 hours. The method improves the quality of the hard pressing, makes the hard pressing material stay in the furnace for a long time, and extends the stable operation period of the furnace type.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and particularly relates to a method for rapid repair of the furnace type in the later stage of blast furnace service with cooling plates. Background Technology

[0002] Taiyuan Iron & Steel Group's No. 6 blast furnace (4350m³) 3 The blast furnace was put into operation on November 7, 2013. The furnace body, from the belly to the middle section, uses 54 layers of copper cooling plates. Layers 1-14 of the belly are entirely made of high-thermal-conductivity graphite bricks. Between layers 14-40, silicon nitride-bonded silicon carbide bricks are inlaid at the front of the graphite bricks to improve the wear resistance of the lining above the waist. Layers 41-54 are entirely made of silicon nitride-bonded silicon carbide bricks. Since 2024, the furnace has been in service for 11 years. Affected by factors such as burden wear, airflow erosion, thermal stress, and alkali metal corrosion, the integrity of the refractory structure has been damaged. In particular, the brick lining between layers 25-37 of the furnace body has largely fallen off, leading to poor uniformity of circumferential airflow, frequent cracking of the furnace shell or cooling plate sheaths, and high concentrations of coal gas on site, posing a significant threat to the safe and stable production of the blast furnace. Summary of the Invention

[0003] The purpose of this invention is to provide a method for rapid repair of the blast furnace shape in the later stages of its service life, which solves the problem that damage to the integrity of the refractory structure of the blast furnace body in the later stages of its service life leads to poor uniformity of circumferential airflow, frequent cracking of the furnace shell or cooling plate sheath, high on-site gas concentration, and poses a significant hidden danger to the safe and stable production of the blast furnace.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for rapid repair of a blast furnace in the later stages of its service life using cooling plates includes the following: (1) Shorten the maintenance cycle The maintenance cycle has been shortened from the normal 4-5 months to 2-3 months. The frequency of grouting in the furnace body has been increased to repair the damaged refractory material in the lower part of the furnace body, so as to achieve uniform circumferential erosion. (2) Openings in the furnace shell During scheduled inspections, grouting holes are drilled at locations where the cooling guard plate cracks or the furnace shell develops cracks. (3) Unblock the grouting holes After removing the ball valve of the grouting hole, use an electric hammer to clear the residual refractory or slag shell inside the furnace. The depth of the cleaning hole should extend 600-700mm from the end face into the furnace, with the standard being the appearance of red coke or red slag. (4) Pressurized feeding During scheduled inspections, a grouting machine is used to press the prepared rigid feedstock into the furnace through new and old grouting holes. (5) Controlling airflow After the ventilation system was overhauled, the loading system was optimized. The platform for ore and coke was widened at the same time, the ore angle difference was increased from 10° to 13°, and the coke angle difference was increased from 13° to 13.5°, and the airflow was controlled. (6) Extend maintenance time The maintenance time has been extended to more than 28 hours, providing more than 4 hours of curing time for the solidification of the hard press feed.

[0005] Preferably, the standard for opening grouting holes in (2) is as follows: the final new hole position is determined based on the frequency of heat load fluctuations in eight directions of the furnace body (0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°), combined with the cracking of the furnace shell or cold plate protection plate at the corresponding height and the temperature of the furnace shell exceeding 400°C as measured by manual temperature measurement. The holes are opened from point to surface, gradually forming a network to achieve full coverage of holes on the circumference.

[0006] Preferably, in (4), the outlet pressure of the grouting machine is 2-4 MPa; the inlet pressure is 0.2-0.3 MPa; the pressing speed is 1.5-2.0 t / h; considering the increase in pressure as the height increases, and combined with the actual position and height of the cooling plate, the inlet pressure is increased layer by layer, increasing by 0.02-0.03 MPa per meter.

[0007] Preferably, in step (4), the adjacent and vertical grouting holes are pressed in the order of bottom to top. When a grouting hole is pressed in, all the surrounding holes are closed. The single hole pressing time is 10-16 minutes. After the pressing is completed, the pressing hole valve is closed and sealed in time.

[0008] Preferably, in step (4), the amount of hard grout is dynamically adjusted according to the cracking and unblocking of the furnace shell. The amount of grout pressed into a single new grouting hole is adjusted from 400kg-450kg to 300kg-350kg, and the amount of grout pressed into a single old grouting hole is adjusted from 450kg-500kg to 350kg-400kg. In areas with frequent fluctuations in heat load, the amount of grout pressed into the hole is increased by 50kg-100kg.

[0009] Preferably, step (5) further includes dynamically adjusting the edge load according to the heat load. When the total heat load is less than 11000*10MJ or the heat load of layers 1-13 is greater than 3000*10MJ, O:343222 is adjusted to O:333222; when the total heat load is greater than 14000*10MJ, O:333222 is adjusted to O:343222. By optimizing the edge load, W:0.35-0.45 is maintained, and the long-term stable operation of the hard press is achieved by stabilizing the heat load.

[0010] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) By optimizing the charging system, the two airflows in the center and the edge are reasonably allocated. Under the premise of ensuring the airflow in the center, the edge is appropriately loosened to improve the airflow stability and avoid cracking of the furnace shell or the cooling plate sheath. (2) By increasing the frequency of grouting in the furnace body and optimizing the parameters of hard material pressing in the furnace body, adjusting key parameters such as pressure, pressing amount, and curing time, the quality of hard material pressing in is improved, so that the hard material pressing material stays in the furnace for a longer time and extends the stable operation cycle of the furnace. Detailed Implementation

[0011] The technical solution of the present invention will be described in detail below with reference to the embodiments.

[0012] The No. 6 blast furnace at Taiyuan Iron & Steel Plant, commissioned on November 7, 2013, has been in operation for nearly 12 years. Due to friction from the furnace charge and scouring by the gas flow, the refractory materials inside the furnace have suffered varying degrees of erosion and wear, damaging the structural integrity of the refractory material. Furthermore, after the refractory material wears and erodes, localized fluctuations in the furnace heat load can lead to the formation of pipes, causing overheating of the furnace shell (allowable temperature <250℃, controlled temperature <150℃). Uneven temperature distribution in the furnace shell creates stress concentration, easily causing minor deformation of the furnace shell, cracking of the welds between the cooling plates and the furnace shell connecting plates, cracking of the cooling plate guards (copper and steel welding done in the factory), and in severe cases, cracking and severe deformation of the furnace shell. After the furnace lining erodes, slag shedding from the front end of the cooling plates in the lower part of the furnace belly, waist, and body can easily cause burn-in, and wear on the front end of the cooling plates is prone to occur in the upper and middle parts of the furnace body. As the fluctuation range and frequency of furnace body heat load gradually increase, phenomena such as cooling plate cracking, furnace shell cracking, and furnace shell red-hot appear in the 25-37 layer area of ​​the cooling plate. Currently, the area where the furnace shell temperature exceeds the standard has expanded to the 23-37 layer of the flat cooling plate, where cooling plate protective plates are also beginning to blow open and furnace shell cracks are also appearing.

[0013] The method of this invention has been applied to Blast Furnace No. 6 (4350m³) at Taiyuan Iron & Steel Plant. Taking the hard press-fitting overhaul on July 30, 2025 as an example, the last overhaul was on May 30, 2025, and the overhaul cycle is 2 months. The specific implementation plan is as follows: (1) Opening During the scheduled maintenance shutdown on July 30, 2025, the No. 6 blast furnace had 154 existing hard lining holes. Based on the principle of hard lining for the No. 6 furnace body and the working condition of the furnace shell during this maintenance cycle, the furnace shell was found to have obvious gas leakage, high temperature due to heat load fluctuations, and cracks, mainly concentrated in the 0°, 45°, 90°, 180°, 270°, and 315° directions. The furnace shell was opened with 17 new holes (40mm diameter) in areas where the furnace shell had experienced excessively high temperatures (greater than 400°C), cracked cooling plates, and cracked furnace shells. A total of 171 grouting holes were opened, and hard lining was used to repair the furnace lining. This effectively formed a stable working layer, which to a certain extent blocked the heat transfer between the high-temperature gas flow inside the furnace and the furnace shell, reduced the temperature of the blast furnace shell, and reduced the occurrence of accidents such as furnace shell overheating and cracking. (2) Unblocking the hole After clearing the 171 holes below the furnace shell and removing the ball valves of the grouting holes, use an electric hammer (25mm drill bit) to clear the residual refractory material or slag shell inside the furnace. The depth of the cleaning holes should extend 600-700mm from the end face into the furnace (100mm short pipe length, 70mm furnace shell thickness), with the sight of red coke or red slag as the standard. When clearing the holes, the residual thickness of the pressed material inside the holes should be checked, and it should be confirmed whether there is any pulverization of the pressed material inside the holes. The strength of the pressed material should also be analyzed. (3) Grouting Adjacent and vertical grouting holes are pressed in the order of bottom to top. When a grouting hole is pressed in, all surrounding holes are closed. The single-hole pressing time for old grouting holes is 15 minutes, and the single-hole pressing time for new grouting holes is 14 minutes. Grouting machine pressure control: Grouting machine outlet pressure: 2-4 MPa; inlet pressure: 0.2-0.3 MPa; grouting speed: 1.5-2.0 t / h; Considering the increased pressure due to height increase, and combined with the actual position and height of the cooling plate, the inlet pressure is increased layer by layer, by 0.02-0.03 MPa per meter; The single-hole injection amount for new grouting holes is 300-350 kg, and the single-hole injection amount for old grouting holes is 350-400 kg; to ensure that the injected material forms a certain furnace lining area and strength in the furnace. After the pressing is completed, the valve of the pressing hole should be closed and sealed in time; repeat the operation until all holes are pressed in, and check the weld for leakage during the pressing process. After exhausting for 30 minutes, stop spraying water on the outside of the furnace. Ensure that the curing time is greater than 4 hours before supplying air; (4) After the air supply is repaired, the air volume is 1000m³. 3 The spray water volume of the main furnace body is gradually increased at speeds above a certain rate, and the charging system is optimized as shown in Table 1 below. Airflow control is implemented to ensure stable central airflow while appropriately loosening the edge airflow. At the same time, the edge load is dynamically adjusted according to the heat load. If the total heat load is below 11000*10MJ or the heat load of layers 1-13 is >3000*10MJ, O:343222 is adjusted to O:333222; if the total heat load is above 14000*10MJ, O:333222 is adjusted to O:343222. The edge temperature is controlled at 80-100℃, and W:0.35-0.45. This reduces the scouring of the newly pressed material in the furnace body by unidirectional airflow fluctuations, extends the stabilization period of the pressed material as much as possible, and ensures the stable operation of the blast furnace. Table 1. Loading System ; (5) The maintenance time is 28 hours.

[0014] By shortening the maintenance cycle, repeatedly drilling holes in the furnace body and grouting them with special refractory material, a 100-200mm working layer is formed between the cooling plates after solidification, replacing the original brick lining. Combined with adjustments to the charging system, this achieves stable furnace operation, helps ensure uniform circumferential airflow, reduces cracking in the lower part of the furnace shell, and promotes safe, stable, economical, and long-lasting blast furnace production. Existing furnace interior spraying only maintains the furnace shape for about six months, and the preparation and construction process takes about 4-6 days. This method allows for rapid construction during maintenance periods, reducing costs.

Claims

1. A method for rapid repair of a blast furnace shape in the later stages of its service life using a cooling plate, characterized in that... Includes the following: (1) Shorten the maintenance cycle The maintenance cycle has been shortened from the normal 4-5 months to 2-3 months. The frequency of grouting in the furnace body has been increased to repair the damaged refractory material in the lower part of the furnace body, so as to achieve uniform circumferential erosion. (2) Openings in the furnace shell During scheduled inspections, grouting holes are drilled at locations where the cooling guard plate cracks or the furnace shell develops cracks. (3) Unblock the grouting holes After removing the ball valve of the grouting hole, use an electric hammer to clear the residual refractory or slag shell inside the furnace. The depth of the cleaning hole should extend 600-700mm from the end face into the furnace, with the standard being the appearance of red coke or red slag. (4) Pressurized feeding During scheduled inspections, a grouting machine is used to press the prepared rigid feedstock into the furnace through new and old grouting holes. (5) Controlling airflow After the ventilation system was overhauled, the loading system was optimized. The platform for ore and coke was widened at the same time, the ore angle difference was increased from 10° to 13°, and the coke angle difference was increased from 13° to 13.5°, and the airflow was controlled. (6) Extend maintenance time The maintenance time has been extended to more than 28 hours, providing more than 4 hours of curing time for the solidification of the hard press feed.

2. The method for rapid repair of a blast furnace type in the later stage of its service life using a cooling plate, as described in claim 1, is characterized in that... The standard for opening grouting holes in (2) is as follows: the final new hole location is determined based on the frequency of heat load fluctuations in eight directions of the furnace body (0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°), combined with the cracking of the furnace shell or cold plate protection plate at the corresponding height and the location of the furnace shell with a temperature greater than 400°C as measured by manual temperature measurement. The holes are opened from point to surface, gradually forming a network to achieve full coverage of holes on the circumference.

3. The method for rapid repair of a blast furnace shape in the later stage of its service life using a cooling plate, as described in claim 1, is characterized in that... The grouting machine outlet pressure in (4) is 2-4 MPa; inlet pressure is 0.2-0.3 MPa; and the grouting speed is 1.5-2.0 t / h. Considering the increased pressure due to the increase in height, and taking into account the actual position and height of the cooling plate, the inlet pressure is increased layer by layer, with an increase of 0.02-0.03 MPa per meter.

4. The method for rapid repair of a blast furnace shape in the later stage of its service life using a cooling plate, as described in claim 1, is characterized in that... In step (4), the adjacent and vertical grouting holes are pressed in the order of bottom to top. When a grouting hole is pressed in, all the surrounding holes are closed. The pressing time for a single hole is 10-16 minutes. After the pressing is completed, the valve of the pressing hole is closed and sealed in time.

5. A method for rapid repair of a blast furnace type in the later stages of its service life using a cooling plate, as described in claim 1, characterized in that... In (4), the amount of hard grout is dynamically adjusted according to the cracking and unblocking of the furnace shell. The single-hole grouting amount of new grouting holes is adjusted from 400kg-450kg to 300kg-350kg, and the single-hole grouting amount of old grouting holes is adjusted from 450kg-500kg to 350kg-400kg. In areas with frequent heat load fluctuations, the grouting amount is increased by 50kg-100kg.

6. The method for rapid repair of a blast furnace type in the later stage of its service life using a cooling plate, as described in claim 1, is characterized in that... The (5) also includes dynamically adjusting the edge load according to the heat load. If the total heat load is less than 11000*10MJ or the heat load of layers 1-13 is greater than 3000*10MJ, O:343222 is adjusted to O:333222; if the total heat load is greater than 14000*10MJ, O:333222 is adjusted to O:343222. By optimizing the edge load, W:0.35-0.45 is maintained, and the long-term stable operation of the hard press is achieved by stabilizing the heat load.