Method for stabilizing blast furnace and improving smelting index after large oxygen enrichment of blast furnace

Abstract

The invention relates to the technical field, in particular to a method for stabilizing a blast furnace and improving smelting indexes after large oxygen enrichment of the blast furnace. The method comprises the following steps: S1, adjusting ore, blast furnace center and edge coke distribution angles and edge coke distribution turns, and expanding ore batches; s2, the coal injection amount is adjusted, and the theoretical combustion temperature in front of a tuyere is controlled to be smaller than or equal to 2350 DEG C; s3, the opening degree of a valve group is adjusted, and the furnace top pressure is increased by 10 kPa to 20 kPa compared with the standard; s4, the fluctuation of the content of iron ore entering the furnace is controlled to be smaller than or equal to + / -0.5%, the silicon content of pig iron is controlled to be 0.25%-0.65%, and the temperature of molten iron is controlled And S5, the ratio of CaO to Al in the slag is controlled to be 1.16-1.20, MgO is larger than or equal to 8.5% and smaller than or equal to 16%, and the ratio of Mg to Al is 0.6-0.7. Through multi-parameter collaborative optimization, edge airflow is restrained from being too strong, furnace condition faults are avoided, oxygen enrichment and high-coal-ratio efficient matching is achieved, the coal gas utilization rate is increased, fuel consumption is reduced, meanwhile, the slag iron performance and pig iron quality are guaranteed, and the purposes of stable and smooth operation of the blast furnace, yield increasing and consumption reducing are achieved.

Description

Technical Field

[0001] This invention relates to the technical field, and in particular to a method for stabilizing a blast furnace and improving smelting indicators after heavy oxygen enrichment. Background Technology

[0002] As an important blast furnace intensification technology, oxygen-enriched blast furnace plays a crucial role in increasing output and reducing carbon emissions. It is currently an important way for blast furnaces to achieve low-carbon smelting. Oxygen enrichment directly increases the oxygen content in the blast, leading to higher theoretical combustion temperature, increased pulverized coal combustion rate, improved smelting intensity, and improved hearth thermal state. With a constant fuel ratio, a 1% increase in oxygen enrichment rate increases blast furnace smelting intensity by 4.76%. However, excessive oxygen enrichment can have adverse effects on blast furnace smelting, such as insufficient furnace heat due to the downward shift of the high-temperature zone, imbalanced radial temperature distribution in the hearth due to excessive edge airflow, and excessively high combustion temperatures disrupting smooth blast furnace operation.

[0003] The present invention provides a method for stabilizing and improving the performance indicators of a blast furnace after implementing high oxygen enrichment. This method can ensure the stable operation of the blast furnace and optimize and improve its performance indicators after implementing high oxygen enrichment, thereby achieving increased production and reduced energy consumption. Summary of the Invention

[0004] In view of this, the present invention provides a method for stabilizing the blast furnace and improving its performance indicators after the blast furnace is heavily oxygen-enriched.

[0005] Therefore, the present invention provides the following technical solution:

[0006] A method for stabilizing a blast furnace and improving smelting indicators after high oxygen enrichment includes the following steps: S1. Increase the ore batch by adjusting the ore feeding angle, the coke feeding angle near the center ring and the edge of the blast furnace, and the number of coke feeding rings at the edge. S2. By adjusting the amount of pulverized coal injected into the blast furnace, the theoretical combustion temperature in front of the tuyeres is controlled to be ≤2350℃; S3. By adjusting the opening degree of the blast furnace valve group, the blast furnace top pressure is increased by 10~20 kPa compared with the reference pressure; S4. Control the amount of iron ore fed into the furnace. The content fluctuation range is ≤±0.5%, the silicon content in pig iron is controlled at 0.25%~0.65%, and the molten iron temperature is controlled at 1490℃~1520℃; S5. Control the CaO content in the slag. The ratio is 1.16~1.20, and the MgO content is ≥8.5%. The content is ≤16%, and the ratio of Mg to Al is 0.6~0.7.

[0007] Furthermore, in step S1, the ore feeding angle is increased by 1.0° to 2.5° compared to the reference; the coke feeding angle near the center ring is decreased by 4.5° to 8.0° compared to the reference; the number of coke feeding rings at the edge is increased by 1 to 2 rings compared to the reference; and the coke feeding angle at the edge is increased by 0.5° to 1.5° compared to the reference.

[0008] Furthermore, in step S1, the ore batch is increased by 10% to 15% compared to the benchmark.

[0009] Furthermore, in step S2, the amount of pulverized coal injected into the blast furnace is increased by 10% to 20% compared to the baseline.

[0010] Furthermore, in step S2, the formula for calculating the theoretical combustion temperature is as follows: T 理 =1563+0.794T b +40.3w-6f b -k p G m In the formula: T 理 Theoretical combustion temperature, T b The hot air temperature is represented by w; the oxygen enrichment rate of the blower air is represented by f. b For blower humidity; k p G is the calorific value of pulverized coal; m This refers to the amount of coal injected.

[0011] Furthermore, after the furnace top pressure is increased in step S3, the furnace dust blowing rate is controlled at 18~22 kg / t.fe.

[0012] Advantages and positive effects of the present invention: By precisely adjusting the angle and number of rings of the ore and coke charging in step S1 and optimizing the ore batch, the resistance of the descending furnace charge to the rising gas is reduced, and excessive edge airflow is avoided. Combined with the furnace top pressure increase in step S3 and the temperature control in step S4, faults such as temperature imbalance, hanging charge, and collapse in the blast furnace can be avoided, ensuring continuous and stable high-oxygen smelting.

[0013] Step S2 controls the theoretical combustion temperature to ≤2350℃ by adjusting the pulverized coal injection rate, achieving a highly efficient combination of high oxygen enrichment and high coal ratio. Combined with the promoting effect of the reduction reaction by increasing the furnace top pressure in step S3, it can improve the utilization rate of coal gas and reduce the fuel ratio and coke ratio. Step S5 precisely controls the slag composition, ensuring good slag fluidity and desulfurization capacity. Combined with the stable control of the silicon content of pig iron and the temperature of molten iron in step S4, it can significantly improve the first-grade pig iron yield and reduce product quality defects. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 The flowchart illustrates a method for stabilizing a blast furnace and improving smelting indicators after high oxygen enrichment, as provided by this invention. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0017] This invention provides a method for stabilizing a blast furnace and improving smelting parameters after heavy oxygen enrichment, such as... Figure 1 As shown, it includes the following steps: S1. By adjusting the ore charging angle, the coke charging angle near the center and edge of the blast furnace, and the number of coke charging rings at the edge, the ore batch size is increased. The ore batch size is increased by 10%~15% compared to the benchmark, and the ore charging angle is increased by 1.0°~2.5° compared to the benchmark, allowing more ore to diffuse towards the furnace wall edge, increasing the thickness and packing density of the ore layer in the edge area, and improving the airflow resistance at the edge. The coke charging angle near the center is decreased by 4.5°~8.0° compared to the benchmark, the number of coke charging rings at the edge is increased by 1~2 rings compared to the benchmark, and the coke charging angle at the edge is increased by 0.5°~1.5° compared to the benchmark, achieving coke enrichment in the central area and reasonable replenishment in the edge area, resulting in greater resistance to blast furnace burden descent at the edge and less resistance to burden descent in the center.

[0018] The aforementioned adjustments work synergistically to guide the rising gas through the central region where resistance is lower, thus both suppressing furnace wall erosion and uneven feeding caused by excessive edge airflow and ensuring sufficient contact between the gas and ore.

[0019] High oxygen enrichment leads to an increase in the oxygen content of the blast furnace blast, causing a sharp rise in the theoretical combustion temperature before the tuyeres, which can easily disrupt the furnace hearth thermal balance. S2, however, controls the theoretical combustion temperature before the tuyeres to ≤2350℃ by adjusting the blast furnace pulverized coal injection rate; the blast furnace pulverized coal injection rate is increased by 10%~20% compared to the baseline, creating a high coal-to-coal ratio condition. This utilizes the heat absorption characteristics of pulverized coal combustion to offset the heating effect caused by high oxygen enrichment.

[0020] The formula for calculating the theoretical combustion temperature is as follows: T 理 =1563+0.794T b +40.3w-6f b -k p G m In the formula: T 理 Theoretical combustion temperature, T b The hot air temperature is represented by w; the oxygen enrichment rate of the blower air is represented by f. b For blower humidity; k p G is the calorific value of pulverized coal; m This refers to the amount of coal injected.

[0021] By dynamically matching the pulverized coal injection rate with the oxygen enrichment rate of the blast furnace, the theoretical combustion temperature before the tuyeres is strictly controlled within a reasonable range of ≤2350℃. High oxygen enrichment provides sufficient oxygen for the complete combustion of pulverized coal, while a high coal ratio provides sufficient heat for smelting. The two work together to avoid damage to the furnace hearth caused by excessively high combustion temperatures, reduce fuel consumption by replacing coke with pulverized coal, and ensure smelting intensity.

[0022] S3. By adjusting the opening of the blast furnace valve group, the blast furnace top pressure is increased by 10-20 kPa compared to the benchmark. This increased pressure slows the gas flow rate, reducing the gas's ability to carry fine particulate matter within the furnace. This reduces the amount of dust blown out from 26-32 kg / t·fe to 18-22 kg / t·fe, thus reducing raw material loss and dust recovery costs. With the blast volume remaining constant, the increased top pressure leads to a reduction in the volume of blast air in front of the tuyeres and a decrease in blast kinetic energy, preventing airflow turbulence caused by strong kinetic energy impacting the hearth. Due to the increased gas pressure in the hearth region, the partial pressures of CO2 and O2 in the initial gas also increase accordingly, accelerating carbon combustion in front of the tuyeres. Simultaneously, the increased pressure improves the reducing atmosphere, accelerates gas diffusion and chemical reaction rates, which is beneficial for the reduction reaction. It also inhibits the development of direct reduction, promoting the direct reduction reaction to occur at higher temperatures, thereby improving gas utilization.

[0023] S4. Control the amount of iron ore fed into the furnace. The silicon content fluctuation range is ≤±0.5%, controlling the silicon content in pig iron between 0.25% and 0.65% to stabilize the total amount of silicon reduction reactants and avoid furnace temperature fluctuations caused by sudden changes in raw material composition. The molten iron temperature is controlled between 1490℃ and 1520℃. Through the above controls, the hearth temperature is ensured to be stable, avoiding faults such as material hanging and collapse caused by local overheating or insufficient temperature, and providing a stable thermal environment for slag-iron melting, separation, and subsequent product quality assurance.

[0024] S5. Control the CaO content in the slag. The ratio is 1.16~1.20, and the MgO content is ≥8.5%. The slag content is ≤16%, and the Mg to Al ratio is 0.6~0.7. This ensures that the slag has good fluidity and stability, avoiding difficulties in slag-iron separation and poor feeding caused by slag viscosity. The optimized slag has sufficient desulfurization capacity, and within the normal fluctuation range of furnace temperature and slag basicity, it can effectively remove sulfur from pig iron, ensuring the quality of pig iron. The reasonable slag composition can form a protective slag film on the surface of the blast furnace brick lining, reducing slag erosion of the brick lining and extending the service life of the blast furnace equipment. At the same time, the stable slag-iron fluidity further improves the first-grade pig iron yield.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for stabilizing a blast furnace and improving smelting indicators after high oxygen enrichment, characterized in that, Includes the following steps: S1. Increase the ore batch by adjusting the ore feeding angle, the coke feeding angle near the center ring and the edge of the blast furnace, and the number of coke feeding rings at the edge. S2. By adjusting the amount of pulverized coal injected into the blast furnace, the theoretical combustion temperature in front of the tuyeres is controlled to be ≤2350℃; S3. By adjusting the opening degree of the blast furnace valve group, the blast furnace top pressure is increased by 10~20 kPa compared with the reference pressure; S4. Control the amount of iron ore fed into the furnace. The content fluctuation range is ≤±0.5%, the silicon content in pig iron is controlled at 0.25%~0.65%, and the molten iron temperature is controlled at 1490℃~1520℃; S5. Control the CaO content in the slag. The ratio is 1.16~1.20, and the MgO content is ≥8.5%. The content is ≤16%, and the ratio of Mg to Al is 0.6~0.

7.

2. The method for stabilizing a blast furnace and improving smelting indicators after high oxygen enrichment according to claim 1, characterized in that, In step S1, the ore feeding angle is increased by 1.0° to 2.5° compared to the reference; the coke feeding angle near the center ring is decreased by 4.5° to 8.0° compared to the reference; the number of coke feeding rings at the edge is increased by 1 to 2 rings compared to the reference; and the coke feeding angle at the edge is increased by 0.5° to 1.5° compared to the reference.

3. The method for stabilizing a blast furnace and improving smelting indicators after high oxygen enrichment according to claim 1, characterized in that, In step S1, the ore batch is increased by 10% to 15% compared to the benchmark.

4. The method for stabilizing a blast furnace and improving smelting indicators after high oxygen enrichment according to claim 1, characterized in that, In step S2, the amount of pulverized coal injected into the blast furnace is increased by 10% to 20% compared to the baseline.

5. The method for stabilizing a blast furnace and improving smelting indicators after high oxygen enrichment according to claim 1, characterized in that, In step S2, the formula for calculating the theoretical combustion temperature is as follows: T 理 =1563+0.794T b +40.3w-6f b -k p G m In the formula: T 理 Theoretical combustion temperature, T b The hot air temperature is represented by w; the oxygen enrichment rate of the blower air is represented by f. b For blower humidity; k p G is the calorific value of pulverized coal; m This refers to the amount of coal injected.

6. The method for stabilizing a blast furnace and improving smelting indicators after high oxygen enrichment according to claim 1, characterized in that, In step S3, after the furnace top pressure is increased, the furnace dust blowing rate is controlled at 18~22 kg / t.fe.

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