Comprehensive control method for realizing low coke ratio production of blast furnace

Abstract

The invention relates to the field of ferrous metallurgy blast furnace ironmaking, in particular to a comprehensive control method for achieving low coke ratio production of a blast furnace. According to the comprehensive control technology for realizing the low-coke-ratio production of the blast furnace, the coke quality required during the low-coke-ratio production is provided, a certain air supply system and a certain charging system are determined, reasonable gas flow distribution parameters are established, the upper charging system is comprehensively regulated under the condition that the central gas flow is stable and abundant, the center is stabilized, the edge is loosened, and the energy consumption is reduced. Edge and middle gas flow distribution is balanced, the coal gas utilization rate is improved, and low coke ratio production is promoted. A blast furnace operator operates the blast furnace by implementing the patent technology, stable and smooth operation of the furnace condition is promoted, stable production with the coke ratio being 330-350 kg / t and the fuel ratio being 505-515 kg / t can be achieved, the economic indexes of the production technology are obviously improved, and stable, balanced, economical and efficient production of the blast furnace is achieved.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking in iron and steel metallurgy, and more particularly to a comprehensive control method for achieving low coke ratio production in blast furnaces. Background Technology

[0002] Blast furnace smelting production, especially with the increasing size of blast furnaces, requires improved production technology and economic indicators to reflect its economic efficiency and superiority. The key lies in low coke ratio and low fuel ratio production. However, once the coke ratio is low enough, the coke load is as high as 5.1 or more, resulting in a thin coke layer in the furnace. This makes it difficult to control the gas flow in the furnace, especially the center, which is difficult to blow through. This leads to insufficient and unstable gas flow in the center, which in turn makes it difficult to control the stability of the gas flow at the edges. Ultimately, this affects the long-term stable operation and economy of the blast furnace.

[0003] To achieve economical production in modern blast furnaces, the main approach is to produce with a low coke ratio and a low fuel ratio. This involves replacing more expensive coke with cheaper pulverized coal to reduce production costs and alleviate environmental burdens related to coking and transportation. However, during blast furnace smelting, the relatively heavy coke load during low coke ratio production can lead to difficulties in controlling the gas flow and persistently high coke and fuel ratios if the upper and lower operating systems are not properly matched. Therefore, a comprehensive control technology for low coke ratio production in blast furnaces is proposed.

[0004] To achieve low coke ratio production in blast furnaces, controlling coke quality and stabilizing the gas flow distribution within the furnace are crucial. In modern blast furnaces operating at low coke ratios, changes in raw material quality, equipment operation, slag and iron discharge procedures, and slag and iron calorific value can all lead to variations in the gas flow distribution. Once the gas flow within the furnace becomes unbalanced, it can cause significant losses to the smooth operation of the blast furnace and its technical and economic indicators.

[0005] This method aims to provide a comprehensive control technology for blast furnace production with low coke ratios. It proposes determining reasonable coke quality requirements, as well as specific blast and charging systems. By implementing this comprehensive control technology, specific requirements are set for coke quality, and the gas flow from the sides and center of the blast furnace is balanced during operation, thereby achieving long-term stable and economical blast furnace production at low coke ratios (330-350 kg / t). It also achieves a reasonable gas flow distribution within the furnace, ensuring long-term stable and smooth furnace operation at low coke ratios and promoting "high-efficiency, stable, balanced, and economical" production. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned problems by providing a comprehensive control method for achieving low coke ratio production in blast furnaces.

[0007] The purpose of this invention is achieved as follows: a comprehensive control method for low coke ratio production in blast furnaces, comprising the following aspects: (1) ensuring stable coke quality supply, requiring large blast furnace coke with cold strength M40: 88-90, M10: 5.4-6.0, hot performance CSR: 68-72, and reactivity CRI: 20-25; and medium blast furnace coke with cold strength M40: 82-86, M10: 6.0-7.0, hot performance CSR: 65-68, and reactivity CRI: 23-27, and maintaining coke hopper occupancy at 70%-90%; (2) establishing reasonable initial gas flow distribution parameters in the hearth, controlling the standard wind speed to reach 235-250 m / s and the actual wind speed to reach 265-280 m / s under normal production air volume and furnace top pressure, and the blast kinetic energy of medium blast furnaces to reach 11000-12500 kJ / s. g.m / s, large blast furnace blast kinetic energy 15000-16500kg.m / s; (3) Under the condition that the equipment capacity allows, expand the ore batch, and achieve a larger coke batch of 10.4-10.8t production at a low coke ratio of 330-350kg / t, and control the coke layer thickness at the furnace waist to reach 200-225mm; (4) Through comprehensive adjustment of the upper and lower parts, based on the stability of the center and the loosening of the edges, determine the proportion of coke in the center of the blast furnace with coke addition of the center to be 22%-25%, the relative load of edge ore and coke to be stable at 0.97-1.05, the temperature of the cross temperature measurement edge to be controlled to 80-100℃, the W value to be 0.50-0.70, the CCT2 to be controlled to 280-350℃, the gas utilization rate to be 48.5%-50%, the heat load of the medium blast furnace body to be stable at 65,000-90,000 MJ / h, and the heat load of the large blast furnace to be stable at 110,000-140,000 MJ / h.

[0008] (2) Under normal production conditions, the air volume and furnace top pressure are as follows: the air volume during normal production is 3600-3800 m³ / h. 3 / min, furnace top pressure is 210-220KPa.

[0009] The beneficial effects of this invention are as follows: The No. 3 blast furnace (1800m³) of Taiyuan Iron & Steel Plant was put into operation on July 31, 2007. Combining the furnace design and the characteristics of the fully cooled wall structure, a comprehensive operating technology for achieving low coke ratio production in the blast furnace was explored. Through comprehensive adjustments, the overall gas flow was stabilized, the gas utilization rate was improved, and the furnace body heat load was steadily reduced, thereby achieving a significant reduction in the fuel ratio.

[0010] After nearly six months of production practice and exploration, this patented technology and method were invented. According to the changes in the gas flow distribution after the coke load in the furnace increases, the blast furnace operator can adjust the operating system and parameters of the upper and lower parts of the blast furnace in a timely manner, balance the gas flow in the middle and sides, and achieve stable and smooth furnace operation.

[0011] 2. In the first half of 2025, the No. 3 blast furnace was organized for production at a utilization coefficient of 2.8 and an output of 5000 t / d. Through the implementation of comprehensive operation technology for low coke ratio production, the air supply ratio was increased to 2.11, stabilizing the gas flow distribution in the furnace. In the 19 years since the furnace was put into operation, there has been no abnormal corrosion of the refractory material in the furnace body, and as of August 2025, only one water pipe in the furnace cooling wall was damaged, and the overall temperature of the furnace cooling wall was stable and under control. From May to July 2025, the No. 3 blast furnace explored and adjusted its operations. After implementing the above operations, from April to July, it achieved stable production with a silicon content of 0.40% in pig iron, a hot metal temperature of 1490℃, a coke ratio of 339 kg / t, and a fuel ratio of 505-510 kg / t, with good furnace stability and economic benefits. Detailed Implementation

[0012] The basic technical concept of this invention is as follows: In modern blast furnace smelting production with low coke ratio (330-350kg / t), due to the heavy coke load, the adjustment and control of gas flow becomes more difficult, which is manifested in unstable gas utilization rate and furnace body heat load, such as material collapse and deviation, which affects the smooth operation of the blast furnace. The coke ratio and fuel ratio will also remain high, with the coke ratio often increasing to more than 360kg / t, or even higher.

[0013] Here, a comprehensive control technology for achieving low coke ratio production in blast furnaces is proposed. Under the condition of ensuring stable and abundant central airflow, appropriate loosening of the edge operation is adopted to improve the gas utilization rate and reduce the furnace body heat load, thereby achieving the purpose of reducing coke ratio and fuel ratio.

[0014] This comprehensive technology for low coke ratio production in blast furnaces achieves a reasonable and stable distribution of gas flow within the furnace, with a stable and abundant central gas flow and appropriately strong peripheral gas flow. The overall furnace heat load is low, and each temperature zone is active and non-stagnant. The furnace heat load is stable and controllable, thus eliminating the problem of insufficient central gas flow, which can easily occur when the coke load increases with the addition of ore or reduction of coke batches, making it difficult to control the peripheral gas flow and ultimately leading to a refusal to produce low coke ratios. This technology has the following protective features: 1. Stable coke quality supply: For large blast furnaces, the cold strength M40 is 88-90, M10 is 5.4-6.0, hot performance CSR is 68-72, and reactivity CRI is 20-25; for medium-sized blast furnaces, the cold strength M40 is 82-86, M10 is 6.0-7.0, hot performance CSR is 65-68, and reactivity CRI is 23-27, while maintaining a coke bin level of 70%-90%.

[0015] 2. Establish reasonable initial gas flow distribution parameters for the hearth. Under normal production conditions and with the required air volume and furnace top pressure, control the standard wind speed to reach 235-250 m / s, the actual wind speed to reach 265-280 m / s, the blast kinetic energy of medium-sized blast furnaces to reach 11000-12500 kg·m / s, and the blast kinetic energy of large blast furnaces to reach 15000-16500 kg·m / s.

[0016] 3. Within the limits of equipment capacity, expand the ore batch and achieve larger coke batch production at low coke ratios, while controlling the coke layer thickness at the furnace waist to reach 200-225mm.

[0017] 4. Through comprehensive adjustments to the upper and lower parts, focusing on stabilizing the center and loosening the edges, the proportion of coke in the center of the blast furnace with central coking is determined to be 22%–25%, the relative load of ore and coke at the edge is stabilized at 0.97–1.05, the edge temperature of the cross temperature measuring device is controlled at 80–100℃, the W value is 0.50–0.70, the CCT2 is controlled at 280–350℃, the gas utilization rate is 48.5%–50%, the furnace body heat load of medium-sized blast furnaces is stabilized at 65,000–90,000 MJ / h, and that of large blast furnaces is stabilized at 110,000–140,000 MJ / h.

[0018] By improving the above comprehensive adjustments, the blast furnace can achieve long-term stable operation under low coke ratio (330-350 kg / t) and low silicon smelting production conditions, and has strong resistance to disturbances such as air blockage and fluctuations in raw material and fuel quality.

[0019] Implementing this method enabled the Taiyuan Iron & Steel Group's No. 3 blast furnace (1800m³) to achieve [the desired effect]. 3 After May 2025, the furnace stability improved significantly, as evidenced by a decrease in differential pressure from 185 kPa to 170 kPa, a decrease in CCT2 from 350-380℃ to 300-330℃, an increase in edge temperature from 65℃ to 75-95℃, an increase in W value to 0.53, and a decrease in furnace heat load from 115,000 MJ / h to 75,000 MJ / h. The overall furnace stability was significantly improved, the coke ratio decreased from 355 kg / t in the first quarter to 335-340 kg / t in the second quarter, and the fuel ratio decreased from 525 kg / t to 505-510 kg / t, resulting in significant economic benefits.

[0020] The specific technical solution of this invention is as follows: A comprehensive control technology for achieving low coke ratio production in blast furnaces is proposed. 1. For the No. 3 blast furnace, when producing low coke ratio, the following requirements are made: cold coke strength M40: 82-86, monthly average 85.6; M10: 6.0-7.0, monthly average 6.7; hot coke performance CSR: 65-68, monthly average 67.2; reactivity CRI: 23-27, monthly average 24.3; and maintaining coke hopper level at approximately 85%.

[0021] 2. Stable air supply system: based on the No. 3 blast furnace (1800m³) 3For example, the working area of ​​the air vent is 0.2620~0.2680m². 2 The furnace top pressure is 215–220 kPa. The daily operating air volume is 3730–3800 m³ / min, and the oxygen enrichment is 12000–14000 m³ / min. 3 / h, standard wind speed reaches 235~250m / s, stable humidity 10~15g / m 3 The air temperature is 1200-1230℃, the actual wind speed reaches 265-275m / s, and the blast kinetic energy is 11000-12000kg.m / s, achieving a reasonable primary gas flow distribution in the furnace.

[0022] 3. Main principles of gas flow control: Stabilize the center and loosen the edges: 1) Adjust the angle difference between ore and coke feeding. Adjust the angle of the first two stages of ore and coke feeding so that the coke angle is 0.5° to 0.8° higher than the ore angle, and the last stage of coke angle is 0.2° to 0.5° lower than the ore angle. At the same time, stabilize the ore platform angle difference at 12° to 13° and the coke platform angle difference at 12.5° to 13.5°. This ensures that the coke feeding point lands before the ore, effectively loosening the edges. 2) For blast furnaces with added coke in the center, maintain the coke ratio in the center at 22% to 25% and the gas utilization rate at 48.5% to 50%. 3) Through comprehensive adjustment, stabilize the edge ore-to-coke load ratio at 0.95 to 1.05, adjust the edge temperature of the cross-shaped temperature measuring device to 75-95℃, and control the W value (W is the average temperature of the four points at the edge of the cross-shaped temperature measuring device divided by the average temperature of the four points at the top of the furnace) to between 0.5 and 0.70, achieving a good effect of loosening the edges.

[0023] After the above adjustments, the furnace stability was significantly improved. With the implementation of low-silicon smelting, the fuel ratio in daily production operations can be reduced to 500-515 kg / t.

[0024] By implementing this method, the No. 3 blast furnace (1800m³) of Taiyuan Iron & Steel Group was able to achieve its desired blast rate. 3 The edge coke load ratio decreased from 1.15 initially in March 2025 to 0.97 in late June, effectively loosening the edges. After the edges became looser, the pressure differential decreased from 185 kPa to 170 kPa, the CCT2 (average temperature of four points at the sub-center of the crosshair thermometer on the furnace top) decreased from 350℃ to 280-330℃, the edge temperature increased from 65℃ to 75-95℃, the W value stabilized at 0.5-0.7, and the furnace heat load stabilized from 110,000-120,000 MJ / h to 80,000-90,000 MJ / h. Overall furnace stability was significantly improved, the coke ratio decreased from 355 kg / t to 340-345 kg / t, and the fuel ratio decreased from 520-525 kg / t to 505-510 kg / t.

[0025] From May to July 2025, the No. 3 blast furnace explored and adjusted its operations. After implementing the above-mentioned operations, it achieved stable production with a silicon content of 0.40% in pig iron, a hot metal temperature of 1490℃, a coke ratio of 339 kg / t, and a fuel ratio of 505 kg / t during the same period. The furnace operation stability and economic benefits were both good. Example 1

[0026] This invention has been applied to the No. 3 blast furnace (1800m³) of Taiyuan Iron & Steel Plant. Taking the actual production during March-July 2025 as an example, the specific implementation plan is as follows: 1. Determine a reasonable primary gas flow distribution in the furnace and stabilize the air volume at 3700-3800m³. 3 / min, furnace top pressure 215-220KPa, achieving stable production with a standard wind speed of 235m / s and an actual wind speed of over 265m / s.

[0027] 2. Experimentally reduce the amount of central coke by adjusting the PWC charging settings from 3, 3, 2, 2, 1, 4 (a total of 15 cycles). Gradually stabilize the PWC charging at 14.3 cycles. The proportion of central coke gradually decreases from 4 / 15 = 26.7% and stabilizes at approximately 3.3 / 14.3 = 23.1%, while maintaining the gas utilization rate between 48.5% and 50%. After continuous experimentation and adjustments, the charging system for the No. 3 blast furnace was basically stable in June and July 2025 as follows.

[0028]

[0029] The ore batch is 53t, the coke batch is 10.3t, the coke load is 53÷10.3=5.15, and the coke ratio is 334kg / t.

[0030] Through comprehensive adjustments, the No. 3 blast furnace achieved the following production conditions: cold coke strength (M10) of 6.5-7.0, hot coke performance (CSR) of 66.5-67.6, reactivity of 23.5-26.0, blast volume of 3700-3800 m³ / min, and blast volume of 12000-15000 m³ / h. From June to July 2025, the edge ore-to-coke load ratio was gradually reduced to 0.97-1.03, the cross temperature measurement (CCT2) decreased from 370-380℃ at the beginning of 2025 to approximately 280-330℃, the edge temperature was adjusted to 75-95℃, the W value was controlled to 0.5-0.6, the furnace body heat load decreased from 115,000 MJ / h to 70,000-85,000 MJ / h, the coke ratio was 340 kg / t, and the fuel ratio was 510 kg / t, ensuring stable production and smooth furnace operation. Example 2

[0031] This invention has been applied to the No. 3 blast furnace (1800m³) of Taiyuan Iron & Steel Plant. Based on stable furnace operation in the second quarter of 2025, it is a comprehensive operational technology for achieving low coke ratio production in the blast furnace. The specific implementation plan is as follows: 1. Determine a reasonable primary gas flow distribution within the furnace, and stably use an air volume of 3700-3800 m³ during normal production. 3 / min, air volume 12000-15000m³ 3 During production, the standard wind speed is controlled at 235-240 m / s, while the actual wind speed reaches 267 m / s.

[0032] 2. Adjust the angle difference between ore and coke feed. For the first two stages, the coke angle should be 0.5 degrees higher than the ore angle. For the last stage, the coke and ore should be basically level. Regulate the airflow in the secondary center. Increase the ore platform angle difference from 12° to 13° and the coke platform angle difference from 13° to 14.5°. Also, the coke feed should land before the ore feed to effectively loosen the edges.

[0033] 3. For blast furnaces using center coking operation, the amount of center coke needs to be gradually reduced. The PWC charging setting is 3, 3, 2, 2, 1, 3.5, totaling 14.5 cycles. After some trial and error, the PWC can be reduced to 14.3 cycles. The proportion of center coke can be further reduced to 3.3 / 14.3=23.1%, and the gas utilization rate can be stabilized at 48.5% to 50%.

[0034] 4. From June to July, the cold coke strength (M10) of the No. 3 blast furnace was 6.5-7.0, the hot coke performance (CSR) was 66.5-67.6, the reactivity was 23.5-26.0, and the blast volume was 3700-3800 m³ / h. 3 / min, air volume 12000-15000m³ 3 / h production time. After the fuel ratio was reduced to 500-510kg / t, the amount of gas produced per ton of iron ore increased from 1300m³ at the beginning of the month. 3 / t reduced to 1250m 3 / t, the furnace heat load was reduced to 70,000-80,000 MJ / h. To prevent thickening at the edges, the material preparation was adjusted by stabilizing the center and loosening the edges. In early June, the angles of PWO43.5, 41.5, 38.5, 35, 31.5, 38.5 (4, 3, 3, 2, 2, 1) were shifted inward as a whole, and the total number of rings of PWO42.7, 40.7, 38, 34, 29.5, 38 (3, 3, 3, 3, 2, 1) was adjusted to 14.8, and the coke stabilization PWC43.5, 41.5, 38, 34, 29.5, 10 (3, 3, 2, 2, 1, 3.3) was adjusted to 14.3. With this adjustment, the edge coke load was reduced to 0.97, CCT2 decreased from 330-380℃ in early June to 280-330℃, with a daily average of 310℃, the edge temperature of the cross temperature measuring device increased from 65-70℃ to 80-90℃, the W value increased from 0.47 in May to 0.55, and the overall furnace heat load decreased from 95,000 MJ / h to 70,000-80,000 MJ / h, resulting in a significant improvement in the overall stability of the gas flow inside the furnace.

[0035] The charging system for the No. 3 blast furnace will remain basically stable from June to July 2025 as follows.

[0036]

[0037] The ore batch was 52.5t, the coke batch was 10.4t, the coke load was 52.5 ÷ 10.4 = 5.05, and the coke ratio was 340 kg / t. By implementing the above-mentioned patented technology, the ore-coke load ratio at the edge of the No. 3 blast furnace (1800m3) of Taiyuan Iron & Steel Group was reduced from 1.13 in May 2025 to 0.97-1.01 in mid-June, and the proportion of coke in the center was reduced to 23.1%, which achieved a good effect of stabilizing the center and loosening the edges. With a looser edge coke load than before, the pressure difference has decreased from 175 kPa to 160 kPa, CCT2 has decreased from 330℃ to around 300℃, the edge temperature has increased from around 70℃ to 80-90℃, the W value has stabilized at 0.55, and the furnace heat load has decreased from 90,000 MJ / h to 75,000 MJ / h. The overall stability of the furnace condition has been significantly improved, the daily operating coke ratio has decreased from 347-350 kg / t to 335-340 kg / t, and the fuel ratio has decreased from 510-515 kg / t to 502-507 kg / t, resulting in significant economic benefits.

[0038] The production technical indicators of the No. 3 blast furnace from January to July 2025 are as follows.

[0039]

[0040] The above description is only a specific embodiment of the present invention, but the structural features protected by the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A comprehensive control method for achieving low coke ratio production in a blast furnace, characterized in that: Including the following aspects: (1) Ensure a stable supply of coke quality. For large blast furnace coke, the cold strength M40 should be 88-90, M10 should be 5.4-6.0, hot performance CSR should be 68-72, and reactivity CRI should be 20-25; for medium blast furnace coke, the cold strength M40 should be 82-86, M10 should be 6.0-7.0, hot performance CSR should be 65-68, and reactivity CRI should be 23-27. Also, maintain a coke inventory of 70%-90%. (2) Establish reasonable initial gas flow distribution parameters for the hearth. Under normal production conditions, control the standard wind speed to 235-250 m / s and the actual wind speed to 265-280 m / s. The blast kinetic energy of medium-sized blast furnaces should reach 11000-12500 kg·m / s, and the blast kinetic energy of large blast furnaces should reach 15000-16500 kg·m / s. (3) If the equipment capacity allows, expand the ore batch and achieve a larger coke batch of 10.4-10.8t at a low coke ratio of 330-350kg / t, and control the coke layer thickness at the furnace waist to reach 200-225mm; (4) Through comprehensive adjustment of the upper and lower parts, based on stabilizing the center and loosening the edges, the proportion of coke in the center of the blast furnace with coke added in the center is determined to be 22% to 25%, the relative load of ore and coke at the edge is stabilized at 0.97-1.05, the temperature at the edge of the cross temperature measurement is controlled at 80-100℃, the W value is 0.50-0.70, the CCT2 is controlled at 280-350℃, the gas utilization rate is 48.5% to 50%, the heat load of the medium blast furnace body is stabilized at 65,000-90,000 MJ / h, and the heat load of the large blast furnace is stabilized at 110,000-140,000 MJ / h.

2. The comprehensive control method for achieving low coke ratio production in a blast furnace according to claim 1, characterized in that: (2) Under normal production conditions, the air volume and furnace top pressure are as follows: the air volume during normal production is 3600-3800 m³ / h. 3 / min, furnace top pressure is 210-220KPa.

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