Blast furnace blow-in middle adjusting method

Abstract

The invention belongs to the technical field of blast furnace smelting, and particularly discloses a blast furnace blow-in middle adjusting method which comprises the four steps of blow-in initial stage cooling schedule setting, middle stage cooling and tuyere cooperative adjustment, dynamic monitoring and emergency treatment and later stage stabilization and parameter callback. The problems of insufficient activity of the hearth, poor stability of the slag crust and unbalanced heat system are solved through the four steps, and after the technical problem is solved, the stability of the slag crust can be improved by 40%, and the heat loss is reduced by 3.5%; the coal gas utilization rate is increased to 44-45%, and the fuel ratio is reduced by 8-10 kg / t; the air volume is stabilized to 4500 m < 3 > / min, and the yield is recovered to 5000 t / d.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of blast furnace smelting, in particular to a method for middle adjustment during blast furnace start-up. BACKGROUND

[0002] Blast furnace start-up is a key link in the smelting process, involving complex physical and chemical reactions and thermodynamic equilibrium. The traditional start-up method has the following problems: Insufficient heat reserve of the hearth: canceling the addition of bottom coke leads to insufficient initial heat of the hearth, the physical temperature (PT) of the molten iron is lower than 1400℃, and the silicon content (Si) decreases significantly (such as Si of the first furnace is only 4.0%, PT 1387℃).

[0003] Poor stability of the furnace condition: the pressure difference is as high as 175kPa (normal ≤165kPa), the permeability index K value is more than 5.5, the suspension and collapse of materials occur frequently, and the air volume is difficult to increase to more than 4200m 3 / min.

[0004] Low efficiency of the cooling system: improper control of the soft water flow and temperature, frequent shedding of the slag skin, increased heat loss, and coal gas utilization rate of only 38-42%.

[0005] Hearth accumulation: the porosity of the dead material column is only 24-26% (normal 32-35%), the liquid permeability index is 0.28-0.32 (normal 0.45-0.55), and the accumulation of unburned coal powder aggravates the size of the central dead material column.

[0006] In view of the above problems, the present application proposes a middle adjustment method, which realizes the rapid and smooth operation of the blast furnace start-up and efficient production through dynamic adjustment of the soft water flow, temperature and coordinated optimization with the tuyere configuration. SUMMARY

[0007] The purpose of the present application is to provide a method for middle adjustment during blast furnace start-up to solve the problems of insufficient hearth activity, poor stability of the slag skin and imbalance of the heat system.

[0008] To achieve the above purpose, the basic scheme provided by the present application is as follows: a method for middle adjustment during blast furnace start-up, comprising the following steps: S1: setting of the cooling system in the initial stage of start-up Within 24h after ignition, the soft water flow is reduced to 5000m 3 / h, the water temperature is 45℃, the hearth is uniformly preheated, the initial setting of the tuyere area is 0.3219m 2 , the tuyere diameter is 110-120mm, and the wind speed is 240m / s; S2: coordinated adjustment of the middle cooling and tuyere Between 24h-72h after ignition, the soft water flow is reduced by 50m 3 / h until down to 4800 m 3 / h, the water temperature is raised to 55℃; and the tuyere is adjusted simultaneously, specifically: the partition diameter is reduced to 100-115 mm, the tuyere area is 0.2963 m 2 , the wind speed is raised to 280 m / s, and the blast kinetic energy is increased to 85-120 kJ / s. S3: dynamic monitoring and emergency treatment Every 2 h, the pressure difference and the coal gas utilization rate are monitored: if the pressure difference is greater than 170 kPa and the K value is greater than 5.0, the wind reduction program is triggered; if the coal gas utilization rate is less than 45%, the air volume is adjusted back to 50 m 3 / min; Suspension material treatment: when the pressure difference is greater than 180 kPa, the air volume is reduced to 3840 m 3 / min, 3 batches of clean coke are added, and the temperature is controlled at 450℃; S4: late stage stability and parameter adjustment After 72 h, the soft water flow is stabilized at 4800 m 3 / h, the air volume is gradually increased to 4500 m 3 / min, the coke load is restored to 3.7, the coal injection amount is adjusted back to 70 kg / t, and the fuel ratio is controlled at 540 kg / t.

[0009] Further, the soft water flow in step S1 is reduced by 10-12%.

[0010] Further, in step S2, the soft water temperature is raised at a rate of ≤2℃ / h, and the heat flux density is stabilized at 12-15 kW / m 2 .

[0011] Further, in the S3 wind reduction program, the reduction is 50 m 3 / min.

[0012] Further, in step S2, if the furnace activity is insufficient, the coal injection amount is reduced to 60 kg / t, the coke load is reduced to 3.2, and the fuel ratio is increased to 570-580 kg / t.

[0013] Further, in step S2, the number of partitions is 4, and each zone includes 7-8 tuyeres.

[0014] Compared with the prior art, the advantages of the present application are: 1. After the implementation of the present application, the slag skin stability can be improved by 40%, the heat loss can be reduced by 3.5%, the coal gas utilization rate can be improved to 44-45%, the fuel ratio can be reduced by 8-10 kg / t, the air volume can be stabilized to 4500 m 3 / min, and the output can be restored to 5000 t / d.

[0015] 2、The present application can reduce the number of slag peeling, compared with the traditional start-up, shorten the recovery period by 50%. DETAILED DESCRIPTION

[0016] The application will be further described in detail by specific embodiments: A method for middle adjustment of blast furnace start-up, comprising the following steps: S1: setting of cooling system in the initial stage of start-up Within 24 hours after ignition, the soft water flow is reduced to 5000 m 3 / h, the water temperature is 45℃, and the furnace hearth is uniformly preheated; the initial setting of the tuyere area is 0.3219 m 2 , the tuyere diameter is 110-120 mm, the wind speed is 240 m / s, and the reduction range of the soft water flow is 10-12%; S2: mid-term cooling and coordinated adjustment of tuyere Between 24 hours and 72 hours after ignition, the soft water flow is reduced by 50 m 3 / h every 4 hours until it is reduced to 4800 m 3 / h, the water temperature is increased to 55℃, the soft water temperature increasing rate is ≤2℃ / h, the heat flux density is stabilized at 12-15 kW / m 2 , and the tuyere is adjusted synchronously during the blast stopping, specifically: the diameter of the partition is reduced to 100-115 mm, the tuyere area is 0.2963 m 2 , the wind speed is increased to 280 m / s, the blast kinetic energy is increased to 85-120 kJ / s; if the furnace hearth activity is insufficient, the coal injection amount is reduced to 60 kg / t, the coke load is reduced to 3.2, and the fuel ratio is increased to 570-580 kg / t; the number of partitions is 4, and each partition includes 7-8 tuyeres; S3: dynamic monitoring and emergency treatment The pressure difference and the coal gas utilization rate are monitored every 2 hours: if the pressure difference is >170 kPa and the K value is >5.0, the blast reduction program is triggered, and the reduction range of the blast reduction program is 50 m 3 / min; if the coal gas utilization rate is <45%, the blast volume is adjusted back by 50 m 3 / min; Suspension material treatment: if the pressure difference is >180 kPa, the blast is reduced to 3840 m 3 / min, 3 batches of clean coke are added, and the temperature is controlled at 450℃; S4: late stage stabilization and parameter adjustment After 72 hours, the soft water flow is stabilized at 4800 m 3 / h, the blast volume is gradually increased to 4500 m 3 / min, the coke load is restored to 3.7, the coal injection amount is adjusted back to 70 kg / t, and the fuel ratio is controlled at 540 kg / t.

[0017] The application of the above method in the start-up of the blast furnace of Bayi Steel is as follows: S1: Setting of cooling system in the initial stage of start-up Within 24 hours after ignition, the soft water flow is maintained at 5000 m 3 / h, the water temperature is 45°C, and the uniform preheating of the hearth is ensured; the initial setting of the tuyere area is 0.3219 m 2 , and the wind speed is 240 m / s.

[0018] S2: Mid-term cooling and coordinated adjustment of tuyere Between 24 hours and 72 hours, the soft water flow is lowered by 50 m 3 / h every 4 hours to 4800 m 3 / h, and the water temperature is raised to 55°C; the tuyere is adjusted synchronously by blowing: the partition is reduced in diameter to 100-115 mm (area 0.2963 m 2 ), the wind speed is raised to 280 m / s, the coal injection amount is reduced from 80 kg / t to 60 kg / t, and the coke load is reduced from 3.5 to 3.2.

[0019] S3: Dynamic monitoring and emergency treatment The pressure difference and the coal gas utilization rate are monitored every 2 hours: if the pressure difference is greater than 170 kPa and the K value is greater than 5.0, the wind reduction program is triggered (50 m 3 / min each time); if the coal gas utilization rate is less than 45%, the air volume is adjusted back by 50 m 3 / min.

[0020] Suspension material treatment: when the pressure difference is greater than 180 kPa, the wind is reduced to 3840 m 3 / min, 3 batches of clean coke are added, and the temperature is controlled at 450°C.

[0021] S4: Late-stage stabilization and parameter adjustment After 72 hours, the soft water flow is stabilized at 4800 m 3 / h, and the air volume is gradually increased to 4500 m 3 / min; the coke load is restored to 3.7, the coal injection amount is adjusted back to 70 kg / t, and the fuel ratio is controlled at 540 kg / t.

[0022] Through the implementation of the method after the start-up of the blast furnace of Bayi Steel, the number of slag skin shedding is reduced by 40%, the PT is stabilized at 1480-1500°C, the Si content is 1.2-1.5%, the output reaches 5000 t / d within 7 days, and the recovery period is shortened by 50% compared with the traditional start-up.

[0023] The above-mentioned are only embodiments of the present application, and the common knowledge of specific structures and characteristics in the scheme is not described too much. It should be pointed out that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope claimed in this application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A method for adjusting the mid-stage of blast furnace start-up, characterized in that, Includes the following steps: S1: Initial Cooling System Setting During Furnace Start-up Within 24 hours of ignition, reduce the soft water flow rate to 5000 m³ / h. 3 / h, water temperature 45℃, ensuring uniform preheating of the furnace hearth; the initial tuyeres area is set to 0.3219m². 2 The air outlet diameter is 110-120mm, and the wind speed is 240m / s; S2: Mid-term cooling and air vent coordination adjustment Between 24 and 72 hours after ignition, reduce the soft water flow rate by 50m³ every 4 hours. 3 / h, until it is reduced to 4800m 3 Up to / h, the water temperature rises to 55℃; simultaneously, the ventilation is stopped and the air outlets are adjusted, specifically: the diameter of each section is reduced to 100-115mm, and the air outlet area is 0.2963m². 2 The wind speed increased to 280 m / s, and the kinetic energy of the blower increased to 85-120 kJ / s; S3: Dynamic Monitoring and Emergency Response Monitor differential pressure and gas utilization rate every 2 hours: if differential pressure > 170 kPa and K value > 5.0, trigger the ventilation reduction procedure; if gas utilization rate < 45%, reduce ventilation by 50 m³ / h. 3 / min callback air volume; Suspended material handling: When the pressure difference is >180kPa, reduce the airflow to 3840m. 3 / min, add 3 batches of clean coke, and control the temperature at 450℃; S4: Post-processing stabilization and parameter callback After 72 hours, the soft water flow rate stabilized at 4800 m³ / h. 3 / h, the air volume is gradually increased to 4500m³ / h. 3 / min, coke load recovered to 3.7, pulverized coal injection rate adjusted back to 70kg / t, and fuel ratio controlled at 540kg / t.

2. The method for adjusting the blast furnace during start-up according to claim 1, characterized in that, The reduction in soft water flow rate in step S1 is 10-12%.

3. The method for adjusting the blast furnace during start-up according to claim 1, characterized in that, In step S2, the heating rate of the soft water is ≤2℃ / h, and the heat flux density is stable at 12-15kW / m³. 2 .

4. The method for adjusting the blast furnace during start-up according to claim 1, characterized in that, The reduction in airflow in S3 is 50m. 3 / min.

5. The method for adjusting the blast furnace during start-up according to claim 1, characterized in that, In step S2, if the hearth activity is insufficient, the coal injection rate is reduced to 60 kg / t, the coke load is reduced to 3.2, and the fuel ratio is increased to 570-580 kg / t.

6. The method for adjusting the blast furnace during start-up according to claim 1, characterized in that, The number of zones in step S2 is 4, and each zone includes 7-8 air vents.