Method for improving furnace condition fluctuation

Abstract

The invention belongs to the technical field of blast furnace metallurgy, and particularly relates to a method for improving furnace condition fluctuation, which comprises the following steps of: (1) enhancing raw material quality management and optimizing a raw material structure: (1) enhancing raw material quality management: (1) optimizing factory material stacking management; (2) optimizing material inspection and test management; 2, optimizing the raw material structure; 3, optimizing the coke quality; and (2) reducing the coke ratio, improving the coal ratio and improving the smelting strength amplitude, and reasonably controlling: 1, reasonably controlling the adjustment amplitude of the coke ratio; 2, the coal ratio is reasonably adjusted; 3, air is added, oxygen is enriched, and the blast furnace smelting strength is reasonably controlled; according to the method, the raw material quality, the coke extraction ratio and the coal reduction ratio are improved, the smelting strength range is reasonably improved and controlled, and the contradiction between furnace burden decline and coal gas rise is relieved; and frequent fluctuation of furnace conditions is avoided, the stability of the furnace conditions is improved, the yield of the blast furnace is recovered and improved, the coke reduction ratio and the coal extraction ratio are stabilized, and the recovery cost of the furnace conditions of the blast furnace is reduced.

Description

Technical Field

[0001] This invention belongs to the field of blast furnace metallurgical technology, and particularly relates to a method for improving furnace condition fluctuations. Background Technology

[0002] During blast furnace operation, factors such as a decline in the quality of external raw materials and fuels can lead to decreased permeability of the blast furnace charge, changes in gas flow distribution, failure to adjust blast furnace operating procedures in a timely manner, fluctuations in furnace conditions, or the need for blast furnace system maintenance, troubleshooting, or other reasons requiring reduced or shut-down operations. After reduced or shut-down operations, parameters such as the blast furnace hearth condition, furnace temperature, gas flow distribution, charge permeability, and pressure will change, affecting the furnace condition. Therefore, measures need to be taken to restore the blast furnace condition to a normal level (indicators of a normal blast furnace condition include: full blast, stable blast pressure and volume, smooth blast curve, uniform and smooth charging, no material collapse or hanging, stable and reasonable gas flow distribution, sufficient hearth heat, and uniform and active tuyeres). Blast furnace condition restoration typically involves reducing blast or blast pressure, increasing the coke ratio, and controlling the furnace strength. Once the gas flow stabilizes, further restoration is achieved by increasing blast, increasing oxygen enrichment, and adjusting the coke ratio to bring the blast furnace condition back to a normal level. During the subsequent blast furnace condition recovery process, the accuracy of blast furnace strength enhancement and coke ratio reduction was not properly controlled: the strength enhancement (increasing air and oxygen enrichment) was not matched with the burden and furnace condition acceptance capacity; the coke ratio reduction was too rapid and not adapted to the permeability of the burden, causing the blast furnace condition to fluctuate again. Summary of the Invention

[0003] The purpose of this invention is to provide a method for improving blast furnace condition fluctuations, and to solve the problem that the blast furnace condition fluctuates again due to inadequate control over the accuracy of improving metallurgical strength and reducing coke ratio during the blast furnace condition recovery process.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for improving furnace condition fluctuations includes the following: (i) Strengthen raw material quality management and optimize raw material structure 1. Strengthen raw material quality management (1) Optimize the management of incoming material storage; (2) Optimize material inspection and testing management; 2. Optimize raw material structure 3. Optimize coke quality (ii) Reasonably control the extent to which the coke ratio is reduced, the coal ratio is increased, and the metallurgical strength is improved. In the initial stage of furnace condition recovery, the coke ratio is increased to 410-430 kg / t to improve the permeability of the feed column and create conditions for increasing blast. The coke ratio is maintained at 375-385 kg / t for a relatively long period, the duration of which is affected by the improvement of coke quality and the furnace's capacity to handle the load, and is maintained for 8-12 hours. Simultaneously, the furnace strength and oxygen enrichment are reasonably controlled (oxygen is stopped if necessary) to stabilize the gas flow. After the gas flow stabilizes, blast is gradually and orderly increased to restore the air volume. Based on the furnace condition recovery process and in conjunction with the furnace strength and oxygen enrichment status, the coke ratio is reduced in stages and the coal ratio is increased in a stable and orderly manner. The specific operation is as follows: 1. Reasonably control the focal ratio adjustment range The key points for blast furnace condition recovery and adjustment are a coke ratio of 410-430 kg / t and 375-385 kg / t. A coke ratio of 410-430 kg / t is crucial for stabilizing the blast furnace gas flow during the initial stage of blast furnace condition fluctuations, and should be maintained for 16-20 hours. A coke ratio of 375-385 kg / t should be maintained for 8-12 hours. When the coke ratio decreases from 375-385 kg / t to 360-365 kg / t, the decrease should be controlled at 8-10 kg / t every 4-6 hours. Within 8 hours, the coke ratio should be steadily and orderly reduced to 360-365 kg / t, and maintained at 360-365 kg / t for more than 12 hours. Subsequent decreases should be 3-5 kg / t each time, with intervals of more than 7 hours. Maintaining a minimum coke ratio of 345-350 kg / t is essential to ensure a coke layer thickness of 575 mm-655 mm in the furnace throat, improve the thickness of the softening layer coke window, and ensure the permeability of the softening layer coke window. 2. Adjust the coal ratio appropriately The coal ratio of 140-150 kg / t is the key period for the blast furnace to recover and improve its smelting strength. After running for 24-30 hours, the blast furnace reaches its heat balance point, which is conducive to gradually strengthening the smelting and stabilizing the gas flow. 3. Increase air volume, enrich oxygen, and rationally control blast furnace strength. The blast furnace gas flow is stabilized by reducing air and oxygen (and stopping oxygen if necessary); after the blast furnace gas flow is stabilized, air and oxygen are gradually and steadily increased to restore the blast furnace strength, adapting to the blast furnace condition and acceptance capacity.

[0005] Preferably, the specific content of optimizing the management of incoming material stacking in 1 of (a) is as follows: each coke is strictly stacked separately according to the manufacturer and quality, abnormal coke and unqualified coke are stacked separately, a plan is made when using it, and the feeding is strictly in accordance with the batching plan to ensure the accuracy of the blast furnace coke ratio.

[0006] Preferably, the specific content of optimizing material inspection and testing management in (1) is as follows: sampling and testing of various materials under the blast furnace trough, taking samples once per hour for 4-6 hours, and finally making a comprehensive sample composition to ensure accurate test results and guide production; increasing the frequency of coke inspection and testing upon entering the plant, ensuring that at least 7-8 kinds of coke are tested for quality every day, and doing a good job of continuous tracking and timely early warning.

[0007] Preferably, the specific operation of optimizing the raw material structure in step (a) is as follows: The lump ore ratio was adjusted from 13.0-15.0% to 5.0-6.0%, Newman ore was discontinued, and 5.0-6.0% of South African ore was added. The basicity was adjusted by changing the sintering and pelletizing ratios, and the proportion of clinker fed into the blast furnace was increased from 85.0-87.0% to 94.0-95.0%.

[0008] Preferably, the specific operation for optimizing coke quality in step (a) is as follows: (1) Coke structure adjustment: Improve coke quality, increase the proportion of top-charged coke, and maintain the proportion of top-charged coke at 40-60%; (2) Optimization of coke feeding order: 30-50% of the top-charged coke is placed in the center to improve the quality of the central material and stabilize the central airflow.

[0009] Preferably, the specific operation of adding air and oxygen in step (ii) is as follows: (1) Air supply process: When the hot air pressure is ≤355kpa, the air supply range is controlled at 8-10kpa every hour, and the air supply range is controlled at 3-5kpa / time, with an interval of 20-30 minutes. It is separate from the oxygen enrichment of the blast furnace and does not overlap, and the furnace condition acceptance capacity is fully considered. (2) Oxygen-enriched process: hot air pressure at 370-380 kPa, oxygen enrichment at 5000-6000 m³ / h 3 / h is the key point. Running for 8-12 hours can alleviate the contradiction between the decrease of furnace charge and the increase of gas, which is conducive to the gradual and orderly improvement of the furnace hearth condition.

[0010] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) By strengthening material storage management, inspection and testing management, optimizing raw material structure and coke quality, we can ensure the quality of raw materials, improve the quality of central coke, and stabilize the central coal flow. (2) After the gas flow stabilizes, gradually and orderly increase the air volume to restore the air volume. According to the furnace condition recovery process and in combination with the metallurgical strength and oxygen enrichment, reduce the coke ratio and increase the coal ratio in stages in an orderly and stable manner to adapt to the permeability of the material column, enhance the furnace condition stability, and avoid furnace condition fluctuations. (3) During the furnace condition recovery process, increase air volume, increase oxygen enrichment, select metallurgical strength and charge column, and match the furnace condition acceptance capacity to enhance furnace condition stability and avoid furnace condition fluctuations; (4) This method combines improving the quality of raw materials, increasing the coke ratio, reducing the coal ratio, and reasonably increasing and controlling the strength of the furnace to alleviate the contradiction between the decrease of furnace charge and the increase of gas; and adapts to the permeability and liquid permeability of the charge column to avoid frequent fluctuations in furnace conditions, improve the stability of furnace conditions, restore and increase blast furnace output, steadily reduce the coke ratio and increase the coal ratio, and reduce the cost of blast furnace condition recovery. Detailed Implementation

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

[0012] Blast furnace No. 6 has a furnace volume of 1380m³. 3 During the material loading process, the furnace condition fluctuated successively at 16:06 on December 14, 2024, 11:30 on December 15, and 8:31 on December 16, 2024, resulting in suspended material. Initially, measures were taken to reduce blast, increase the coke ratio, and control the furnace strength. After the gas flow stabilized, subsequent furnace condition recovery was carried out. However, due to inadequate control over the blast and coke ratio adjustments during the recovery process, frequent fluctuations in furnace condition occurred. This invention addresses this issue by employing a method to improve furnace condition fluctuations, including the following: (i) Strengthen raw material quality management and optimize raw material structure 1. Strengthen raw material quality management (1) Optimize the management of incoming materials: each coke is strictly separated according to the manufacturer and quality, abnormal coke and unqualified coke are stacked separately, a plan is made when using them, and the feeding is strictly in accordance with the feeding plan to ensure the accurate coke ratio of the blast furnace. (2) Optimize material inspection and testing management: At 10:00 on December 17, various materials under the blast furnace trough were sampled and tested. Samples were taken once per hour for 4-6 hours. Finally, a comprehensive sample composition was made to ensure the accuracy of the test results and guide production. At 14:00 on December 17, the frequency of coke inspection and testing was increased to ensure that at least 7-8 types of coke were tested for quality every day, and continuous tracking and timely early warning were carried out. 2. Optimize raw material structure At 6:00 AM on December 17th, the proportion of lump ore was adjusted from 13.5% to 5.0%, Newman lump ore was discontinued, and 5.0% South African lump ore was added. The basicity was adjusted by changing the sintering and pelletizing ratios, and the proportion of clinker fed into the blast furnace increased from 86.5% to 95.0%. 3. Optimize coke quality (Meijin and Shanxi Coke are top-loading coke) At 23:00 on December 15th, Baofeng 1.3S was replaced with Baofeng 1.8S, and the coke structure was adjusted to: Meijin 30% + Yangguang 20% ​​+ Zhongxin 25% + Baofeng (1.8S) 25%; at 14:30 on December 17th, 20% top-loaded coke was replaced with 20% tamped Yangguang coke, and the coke structure was adjusted to: Meijin 30% + Shanjiao 20% + Zhongxin 25% + Baofeng (1.8S) 25%, the top-loaded coke ratio was adjusted from 30% to 50%, and the coke feeding order was optimized: 50% of the top-loaded coke was placed in the center to improve the quality of the coke in the center and stabilize the airflow in the center; (ii) Reasonably control the extent to which the coke ratio is reduced, the coal ratio is increased, and the metallurgical strength is improved. 1. Reasonably control the focal ratio adjustment range The key points for blast furnace condition recovery and adjustment are a coke ratio of 420 kg / t and 380 kg / t. A coke ratio of 420 kg / t is crucial for stabilizing the blast furnace gas flow during the initial stage of furnace condition fluctuations, and should be maintained for 16-18 hours. A coke ratio of 380 kg / t should be maintained for 8-10 hours. The coke ratio should then be reduced from 380 kg / t to 360 kg / t, with the reduction controlled at 8-10 kg / t every 4 hours. Within 8 hours, the coke ratio should be steadily and orderly reduced to 360 kg / t, and maintained at 360 kg / t for more than 12 hours. Subsequent reductions should be made at 3-5 kg / t intervals of more than 7 hours. A minimum coke ratio of 345 kg / t should be maintained to ensure a coke layer thickness of 575 mm-650 mm in the furnace throat, improve the thickness of the softening layer coke window, and ensure the permeability of the softening layer coke window. Detailed information on coke ratio adjustments is as follows: (1) At 8:30 on December 16, the furnace condition was difficult to operate, and the coke ratio increased from 366 kg / t to 420 kg / t; (2) At 0:30 on December 17, the coke ratio dropped to 400 kg / t; at 3:00, the coke ratio dropped to 380 kg / t; at 12:00, the coke ratio dropped to 370 kg / t; at 16:00, the coke ratio dropped to 360 kg / t. (3) By 9:00 on December 18, the coke ratio dropped to 355 kg / t; by 17:00, the coke ratio dropped to 350 kg / t; (4) By 7:00 on December 19, the coke ratio had dropped to 345 kg / t; 2. Adjust the coal ratio appropriately A coal ratio of 140-150 kg / t is crucial for the blast furnace to recover and enhance its smelting strength. After 24-30 hours of operation, the blast furnace reaches its heat balance point, which facilitates gradual intensification of smelting and stabilizes the gas flow. Details regarding coal ratio adjustments are as follows: (1) At 9:00 on December 16, the coal ratio dropped to 80 kg / t, and at 1:00 on December 17, the coal ratio increased to 110 kg / t; at 6:00, the coal ratio increased to 120-130 kg / t; at 8:00, the coal ratio increased to 130-140 kg / t; at 13:00, the coal ratio increased to 140-145 kg / t; (2) By 7:00 on December 18, the coal ratio recovered to 150 kg / t; by 0:00 on December 19, the coal ratio recovered to the normal level of 160 kg / t. 3. Increase air volume, enrich oxygen, and rationally control blast furnace strength. The blast furnace gas flow is stabilized by reducing air and oxygen (and stopping oxygen if necessary); after the blast furnace gas flow is stabilized, the blast is gradually and orderly increased and oxygen is enriched to restore the blast furnace strength, which is adapted to the blast furnace condition acceptance capacity. (1) When the hot blast pressure is ≤355kpa, the air increase is controlled at 10kpa every hour, and the air increase is controlled at 3-5kpa / time, with an interval of 20-30 minutes. This is separate from the increase of oxygen in the blast furnace and does not overlap. The furnace condition acceptance capacity is fully considered. (2) When the hot blast pressure is 370-380kpa and the oxygen enrichment is 5000-6000m 3 / h is a key point. Running for 8-12 hours alleviates the contradiction between the descent of the furnace charge and the rise of the gas, which is conducive to the gradual and orderly improvement of the hearth condition. The details of increasing air volume, enriching oxygen, and reasonably controlling the blast furnace strength are as follows: (1) Air supply process a. At 8:31 AM on December 16th, the furnace was under suspension, and the hot blast pressure was reduced from 380 kPa to 320 kPa. Oxygen enrichment was discontinued to stabilize the furnace condition. Once the gas flow stabilized and the furnace condition was acceptable, blast was gradually and steadily increased, prioritizing the restoration of air volume. At 11:00 AM, the hot blast pressure was steadily increased to 330 kPa, and the air volume was 2560 m³ / h. 3 / min; 19:00 Hot air pressure steadily increased to 340kPa, air volume 2780m³ / min; 3 / min; b. At 4:00 AM on December 17th, the hot air pressure was steadily increased to 350 kPa, and the air volume was 2820 m³ / h. 3 / min; 5:00 Hot air pressure is steadily increased to 360kPa, air volume 2920m³ / min; 3 / min; 6:00 Hot air pressure steadily increased to 370 kPa, air volume 2950 m³ / min. 3 / min; at 12:00, the hot air pressure was steadily increased to 375 kPa, and the air volume was 2960 m³ / min. 3 / min; 17:00 Hot air pressure steadily increased to 380kPa, air volume 2975m³ / min. 3 / min; c. At 1:00 AM on December 18th, the hot air pressure was steadily increased to 390 kPa, and the air volume was 2940 m³ / h. 3 / min; 9:00 Hot air pressure is steadily increased to 400kPa, air volume 3020m³ / min; 3 / min, the air pressure returned to normal level, and the furnace continued to operate stably and smoothly; (2) Oxygen-enriched process The oxygen enrichment in the blast furnace should be adapted to the coal ratio, and the initial oxygen enrichment increment should be controlled at 500m. 3 / h, oxygen enrichment reaches 7500m 3 After / h, the oxygen enrichment increment per hour should be controlled at 1000-1500m. 3 / h, with each oxygen enrichment increment ranging from 700-800m. 3 / h, with intervals of 20-30 minutes, reaching an oxygen enrichment level of 12000-13000m. 3 After running for 10-12 hours, based on the furnace condition, the oxygen enrichment level should be gradually restored to normal. The increase in oxygen enrichment should be separated from the blast furnace blasting, avoiding overlap, and fully considering the furnace's tolerance, as follows: a. At 8:31 AM on December 16th, the furnace was under suspension, and the hot blast pressure was reduced from 380 kPa to 320 kPa. Oxygen enrichment was discontinued and will be gradually resumed once the furnace conditions stabilize, the coal ratio is compatible, and the furnace conditions are acceptable. Oxygen enrichment was resumed at 11:00 PM with an enrichment level of 3000 m³. 3 / h; b. At 1:00 AM on December 17th, the oxygen level was steadily increased to 4000m. 3 / h; 2:00 Oxygen enrichment was steadily increased to 4600m 3 / h; 3:00 Oxygen enrichment steadily increased to 5000m 3 / h; 4:00 Oxygen enrichment was steadily increased to 5550m 3 / h; 12:00 Oxygen enrichment was steadily increased to 6500m 3 / h; 13:00, oxygen enrichment was steadily increased to 7500m. 3 / h; 14:00, oxygen enrichment was steadily increased to 9000m 3 / h; 16:00, oxygen enrichment was steadily increased to 10500m. 3 / h; 23:00, oxygen enrichment was steadily increased to 12000m. 3 / h; c. At 2:00 AM on December 18th, the oxygen level was steadily increased to 13000m. 3 / h; 10:00, oxygen enrichment is steadily increased to 13500-14000m. 3 / h is at a normal level; the furnace condition remains stable and operates smoothly.

[0013] After implementing the above plan, the recovery status of Boiler No. 6 improved significantly, mainly as follows: (1) The strength of the metallurgical plant has steadily recovered to normal. By 11:30 on December 17, the furnace condition had returned to normal, and by 9:00 on December 18, the blast pressure had returned to normal levels. From 8:31 on December 16 to December 19, there was no hanging material in the blast furnace, and the furnace condition remained stable throughout the day. (2) Coal ratio recovery and improvement By the 17th, the operating coke ratio had stabilized at 350 kg / t, and by 7:00 on the 19th, the operating coke ratio had stabilized at 345 kg / t. The coal ratio gradually increased to 160 kg / t. From December 18th to 19th, the average operating coke ratio was 349 kg / t, a decrease of 21 kg / t compared to December 14th to 17th, while the coal ratio increased by 25 kg / t, resulting in a reduction of 11.46 yuan / t in the cost of molten iron fuel. (3) Blast furnace output recovered and improved The furnace conditions fluctuated on December 14, 15, and 16. On the 17th, the furnace conditions continued to recover and adjust, and the output gradually decreased. The output from the 14th to the 17th was 4819.28 tons, 4242.38 tons, 3581.01 tons, and 4393.02 tons, respectively. From the 18th to the 19th, the furnace conditions were adjusted and returned to normal, and the output was 4757.99 tons and 4804.16 tons, respectively, gradually completing the company's planned output of 4780 tons / day.

[0014] The principle of blast furnace charge descent: After the blast furnace charge is charged into the furnace, it is fully preheated and reduced by the rising gas flow during the descent process, which enables sufficient heat and mass transfer. Moreover, it can descend evenly, ensuring smooth operation of the blast furnace and reducing energy consumption. Two conditions must be met for the charge descent: First, there must be space for descent; second, there must be effective gravity for descent.

[0015] (a) Forming space for the furnace charge to descend The necessary condition for the formation of a charging charge descent space is the presence of all factors that can reduce or eliminate the volume occupied by the charging charge within the furnace. These factors mainly include the following: 1. Coke burns in front of the tuyeres: Coke accounts for 50%-70% of the total volume of the feed column, and 70%-75% of the carbon is burned in front of the tuyeres. The space formed by the coke combustion in front of the tuyeres is about 35%-40%. 2. Direct reduction consumes carbon: Some of the carbon in coke is consumed due to direct reduction, reducing its volume by about 15%; 3. Ore volume shrinkage: During the descent of the ore, small particles fill the gaps in the furnace charge, and the melting of the ore causes volume shrinkage, resulting in approximately 30% of the space created. 4. Slag and iron removal: The generated liquid slag and iron are discharged outside the furnace, freeing up approximately 15%-20% of the space.

[0016] (ii) Effective gravity of the furnace charge The existence of space for the charge to descend within the furnace does not guarantee its free descent. A force is required to facilitate this descent. Only when this force exceeds the various resistances to descent can the charge descend. A suspended charge (difficult to descend) in a blast furnace is a case in point: even with space for descent, the various resistances encountered during this process are greater than or equal to the force required to descend, causing the charge to remain suspended and unable to descend freely. Analyzing the forces acting on the charge, it descends under the influence of gravity. However, the descent is also subject to forces opposite to gravity, namely the friction between the charge and the furnace walls, the friction between loose materials due to varying descent speeds, and the supporting force (buoyancy) from the rising gas. The pressure loss caused by the obstruction of the charge column during the gas flow is equivalent to the magnitude of the buoyancy. The equilibrium relationship of these forces can be expressed as: F=W重 -P 墙 -P 料 -P 浮 In the formula, F is the force that causes the furnace charge to descend; W 重 The weight of the material itself; P 墙 P is the vertical component of the frictional force between the furnace charge and the furnace wall. 料 P is the perpendicular component of the frictional force between the blocks during relative motion. 浮 W is the total pressure difference when the gas passes through the bed of gas. 重 -P 墙 -P 料 The value is actually the effective weight of the furnace charge after overcoming various frictional forces, expressed in W. 效 If F = W, then 效 -P 浮 ; If W 效 =P 浮 If F=0, the furnace charge will be difficult to move; If W 效 <P 浮 If F < 0, the furnace charge is lifted by the gas, resulting in suspended material, or even carried away by the gas, forming a fluidization phenomenon. If W 效 >P 浮 If F > 0, the furnace charge can descend smoothly, ensuring the normal operation of smelting.

[0017] F=W 效 -P 浮 In the formula, anything that affects W 效 and P 浮 All factors will affect the descent of the furnace charge.

[0018] , The above formula applies Janssen's formula to analyze the force on the bulk material layer in counter-current motion. For a blast furnace, F in this formula represents the effective weight of the burden, which is related to the burden density γ, blast furnace height H, diameter D, gas pressure difference ΔP, frictional force f between the bulk material and the furnace wall, and lateral pressure coefficient n, etc. 1. Effect of increased height: The effective weight of bulk materials increases with increasing height, but when H increases to a certain value... At this time, F = constant, meaning that further increasing the height has no effect on the effective weight; When the blast furnace is in motion, the effective weight of the charge increases because the coefficient of dynamic friction is less than the coefficient of static friction. Domestic model tests show that when the charge is in motion, the effective weight is 39% to 41% of the total weight, and when stationary, it is 15% to 16%. When the blast furnace is stationary, the measured weight of the horizontal fabric at the tuyeres is 18.2% of the total weight. 2. The effect of blast furnace height-to-diameter ratio: When the height-to-diameter ratio of the blast furnace is small, that is, the effective weight of the burden column of the short and fat blast furnace is larger, which is conducive to smooth furnace operation. However, too small a height-to-diameter ratio will worsen the reduction effect of the furnace body and reduce the utilization rate of blast furnace gas. 3. Impact of fuel: Increasing coke load and increasing the density of the furnace charge are beneficial for the settling of the furnace charge, but the coke skeleton is significantly reduced, affecting the permeability; 4. The influence of furnace body angle and furnace belly angle: Increasing the furnace belly angle and decreasing the furnace body angle both reduce the coefficient of friction, which is beneficial for the descent of the furnace charge; however, if the furnace belly angle is too large, the furnace belly brick lining is more likely to be burned; if the furnace body angle is too small, the edge airflow will develop, reducing the gas utilization rate, so all factors must be considered. 5. Impact of furnace walls: Irregular, thick, or nodular furnace walls increase the coefficient of friction, which is not conducive to material feeding; 6. Influence of coefficients: An increase in the lateral pressure coefficient n, such as thermal expansion of the furnace charge, will increase the friction coefficient, which is also not conducive to the smooth descent of the furnace charge; 7. Effect of gas flow rate: The pressure drop of gas is affected by the gas flow rate, and the gas flow rate is approximately linearly related to the air volume. As the air volume increases, ΔP also increases. In actual production, the gas flow rate is approximately proportional to the first power of the air volume. 8. Effects of particle size and porosity: Increasing porosity and the equivalent diameter of airflow through the bulk material layer can reduce ΔP; the equivalent diameter of the bulk material channel is proportional to the average diameter of the material block, so increasing the raw material particle size is beneficial to reducing ΔP. When the diameter of the material block is below 5-10 mm, ΔP increases significantly as the particle size decreases. However, excessively large particle size will prolong the ore preheating and reduction time, increasing fuel consumption. The more uniform the particle size, the greater the porosity of the material column. Therefore, strengthening the granulation of raw materials is an effective measure to reduce ΔP. 9. Effects of gas density and viscosity: Decreasing gas density and viscosity will reduce ΔP. Injecting fuel with high H2 content will have a more significant effect on reducing ΔP. 10. Impact of operational factors: Adopting a charging system that develops the edge will reduce the resistance of gas penetration through the material bed, thus reducing ΔP; 11. The properties and quantity of slag affect the pressure head loss at the bottom. For example, if the slag is viscous or the amount of slag is large, it will hinder the gas from passing through the slag layer and increase the pressure loss. 12. Increased air temperature will increase the viscosity of coal gas. When the air temperature is below 800 ℃, the effect of air temperature on coal gas viscosity is particularly significant. 13. The greater the speed of the furnace charge movement, the greater the porosity between the furnace charge and the smaller the pressure loss of the gas passing through the charge bed.

[0019] This method combines multiple factors affecting the decrease in furnace charge, fully considers the furnace's operating capacity, alleviates the contradiction between the decrease in furnace charge and the increase in gas, enhances the stability of the furnace, restores and increases the daily output of the blast furnace, reduces the maintenance cost of the blast furnace, and increases profits.

Claims

1. A method for improving furnace condition fluctuations, characterized by comprising the following: (i) Strengthen raw material quality management and optimize raw material structure 1. Strengthen raw material quality management (1) Optimize the management of incoming material storage; (2) Optimize material inspection and testing management; 2. Optimize raw material structure 3. Optimize coke quality (ii) Reasonably control the extent to which the coke ratio is reduced, the coal ratio is increased, and the metallurgical strength is improved. In the initial stage of furnace condition recovery, the coke ratio is increased to 410-430 kg / t to improve the permeability of the feed column and create conditions for increasing blast. The coke ratio is maintained at 375-385 kg / t for a relatively long period, the duration of which is affected by the improvement of coke quality and the furnace's capacity to handle the load, and is maintained for 8-12 hours. Simultaneously, the furnace strength and oxygen enrichment are reasonably controlled (oxygen is stopped if necessary) to stabilize the gas flow. After the gas flow stabilizes, blast is gradually and orderly increased to restore the air volume. Based on the furnace condition recovery process and in conjunction with the furnace strength and oxygen enrichment status, the coke ratio is reduced in stages and the coal ratio is increased in a stable and orderly manner. The specific operation is as follows:

1. Reasonably control the focal ratio adjustment range The key points for blast furnace condition recovery and adjustment are a coke ratio of 410-430 kg / t and 375-385 kg / t. A coke ratio of 410-430 kg / t is crucial for stabilizing the blast furnace gas flow during the initial stage of blast furnace condition fluctuations, and should be maintained for 16-20 hours. A coke ratio of 375-385 kg / t should be maintained for 8-12 hours. When the coke ratio decreases from 375-385 kg / t to 360-365 kg / t, the decrease should be controlled at 8-10 kg / t every 4-6 hours, with a stable and orderly decrease to 360-365 kg / t within 8 hours. This coke ratio should be maintained at 360-365 kg / t for more than 12 hours, with subsequent decreases of 3-5 kg / t at intervals of more than 7 hours. A minimum coke ratio of 345-350 kg / t should be maintained to ensure a coke layer thickness of 575 mm-655 mm in the furnace throat.

2. Adjust the coal ratio appropriately The coal ratio of 140-150 kg / t is the critical period for the blast furnace to recover and improve its metallurgical strength. It takes 24-30 hours of operation to reach the heat balance point of the blast furnace.

3. Increase air volume, enrich oxygen, and rationally control blast furnace strength. The blast furnace gas flow is stabilized by reducing air and oxygen (and stopping oxygen if necessary); after the blast furnace gas flow is stabilized, air and oxygen are gradually and steadily increased to restore the blast furnace strength, adapting to the blast furnace condition and acceptance capacity.

2. The method for improving furnace condition fluctuations according to claim 1, characterized in that, The specific contents of optimizing the management of incoming material stacking in (a) of (1) are as follows: each coke is strictly stacked separately according to the manufacturer and quality, abnormal coke and unqualified coke are stacked separately, a plan is made when using it, and the feeding is strictly in accordance with the batching plan to ensure the accuracy of the blast furnace coke ratio.

3. The method for improving furnace condition fluctuations according to claim 1, characterized in that, The specific contents of optimizing material inspection and testing management in (a) 1 are as follows: sampling and testing of various materials under the blast furnace trough, taking samples once per hour for 4-6 hours, and finally making a comprehensive sample composition to ensure accurate test results and guide production; increasing the frequency of coke inspection and testing upon entering the plant, ensuring that at least 7-8 kinds of coke are tested for quality every day, and doing a good job of continuous tracking and timely early warning.

4. The method for improving furnace condition fluctuations according to claim 1, characterized in that, The specific operations for optimizing the raw material structure in section (I) are as follows: The lump ore ratio was adjusted from 13.0-15.0% to 5.0-6.0%, Newman ore was discontinued, and 5.0-6.0% of South African ore was added. The basicity was adjusted by changing the sintering and pelletizing ratios, and the proportion of clinker fed into the blast furnace was increased from 85.0-87.0% to 94.0-95.0%.

5. The method for improving furnace condition fluctuations according to claim 1, characterized in that, The specific operations for optimizing coke quality in section (I) are as follows: (1) Coke structure adjustment: Improve coke quality, increase the proportion of top-charged coke, and maintain the proportion of top-charged coke at 40-60%; (2) Optimization of coke loading order: 30-50% of the top-loaded coke is placed in the center.

6. The method for improving furnace condition fluctuations according to claim 1, characterized in that, The specific operation of adding air and oxygen in section (II) is as follows: (1) Air supply process: When the hot air pressure is ≤355kpa, the air supply range is controlled at 8-10kpa every hour, and the air supply range is controlled at 3-5kpa / time, with an interval of 20-30 minutes. It is separate from the oxygen enrichment of the blast furnace and does not overlap, and the furnace condition acceptance capacity is fully considered. (2) Oxygen-enriched process: hot air pressure at 370-380 kPa, oxygen enrichment at 5000-6000 m³ / h 3 / h is the key point; it should run for 8-12 hours.