Blast furnace blow-in humidification and blast operation method

Abstract

The invention belongs to the technical field of blast furnace smelting, and particularly discloses a blast furnace blow-in humidification blast operation method which comprises the following five steps of initial parameter setting, stepped humidification and air temperature compensation, key parameter real-time monitoring, abnormal furnace condition processing and steady-state optimization. Through the five steps, the problems of thermal unbalance, poor liquid permeability and insufficient reduction of the hearth can be solved, and after the method is implemented, the qualification rate of the content of Si in molten iron can be increased to 95%; the daily average yield is increased by 8-10%; the coal gas utilization rate is increased from 45% to 48%, and the fuel ratio is reduced by 5kg / t.

Description

TECHNICAL FIELD

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

[0002] The blast furnace start-up stage is often difficult to proceed smoothly due to unstable thermal state of the hearth, poor liquid permeability of the dead material column and other problems. The traditional method controls the furnace temperature by adjusting the blast temperature or the coal injection amount, but has the following defects: Theoretical combustion temperature is too high: when the temperature in front of the tuyere exceeds 2150℃, it is easy to cause softening zone fluctuation and imbalance of coal gas distribution; Insufficient reduction capacity: after reducing the coal injection amount, the CO reduction efficiency decreases, and the silicon content of molten iron fluctuates greatly (such as Si < 0.3%); Poor liquid permeability: due to the accumulation of powdered coke and unburned coal powder in the dead material column, the liquid permeability is poor, the pressure difference rises sharply (ΔP > 180kPa), and the air volume is limited to below 4300m 3 / min; Uneven gas flow distribution: excessive edge gas flow (edge CO2% > 24.3%), insufficient central gas flow (central CO2% < 19.5%). The humidified blast technology can reduce the theoretical combustion temperature by heat absorption during water decomposition (H2O→H2+0.5O2, heat absorption 108kJ / mol), and increase the H2 content (reduction efficiency is 5-8 times that of CO), but the existing technology lacks a systematic parameter matching scheme, which easily leads to hydrogen explosion risk (H2 concentration > 5%) or furnace temperature out of control (Si < 0.3%). Therefore, there is an urgent need for an operation method that integrates the coordinated regulation of humidification amount, blast temperature and coal ratio. SUMMARY

[0003] The purpose of the present application is to provide a blast furnace start-up humidified blast operation method, which solves the problems of hearth thermal imbalance, poor liquid permeability and insufficient reduction through a stepwise humidification and dynamic compensation mechanism.

[0004] To achieve the above-mentioned purpose, the basic scheme provided by the present application is: a method for blast furnace start-up humidified blast operation, comprising the following steps: S1: initial parameter setting The reference air volume is set to 4300m 3 / min, the blast temperature is 1150℃, and the coal injection amount is 70kg / t; the initial value of the humidification amount is 10g / m 3 , and the H2 concentration warning threshold of the top gas is set to 2.8%; the theoretical combustion temperature is controlled to 2150℃, the silicon content of molten iron is controlled to 0.4-0.6%, and the physical heat is ≥1480℃; S2: stepwise humidification and blast temperature compensation Increase the humidification amount by 5g / m 3 every 30 minutes until the target value of 30g / m 3; every increase of 10 g / m 3 Humidity, synchronous increase of air temperature 30-50℃; S3: real-time monitoring of key parameters Air flow distribution: real-time monitoring of center and edge CO2% by infrared imager, ensuring that the center CO2% <19.5%, and the edge CO2% >24.3%; Furnace hot state: every 15 minutes to detect the [Si] content and physical heat of molten iron, if the [Si] content of molten iron is less than 0.3% for two consecutive furnaces, reduce the humidity by 10 g / m 3 ; Hydrogen explosion prevention and control: online gas chromatograph monitors H2 concentration, when it exceeds 2.8%, trigger alarm and suspend humidification; S4: steady-state optimization Humidity is stable at 30 g / m 3 , every 2 hours fine-tune the air temperature ±10℃, maintain the [Si] content of molten iron at 0.4-0.6%.

[0005] Further, the increase gradient of the humidity in step S2 is 10→15→20→25→30 g / m 3 .

[0006] Further, the coal injection amount in step S2 is controlled at 60-80 kg / t, and controlling the coal injection amount at 60-80 kg / t can avoid the unburned coal powder offsetting the H2 benefit.

[0007] Further, it further includes an abnormal condition handling step, specifically as follows: Pressure difference rises sharply: immediately reduce the air to 4000 m 3 / min, the humidity is adjusted back to 15 g / m 3 , and 2 batches of clean coke are added, each batch is 5 tons; Low furnace temperature: air temperature increases by 50℃, coal injection amount increases by 5 kg / t, and humidity decreases by 5 g / m 3 ; Central airflow occlusion: adjust the distribution matrix, increase the coke distribution angle from 35° to 40°, and reduce the ore distribution angle from 30° to 25°.

[0008] Further, in step S4, the oxygen enrichment amount is adjusted according to the target coal gas utilization rate, and every change of 1% of the oxygen enrichment amount corresponds to an air volume of ±50 m 3 / min.

[0009] Further, the index corresponding to the sharp rise in pressure difference is ΔP>180kPa, and the index corresponding to the low furnace temperature is [Si] content of molten iron <0.3%.

[0010] Further, in step S3, when the H2 concentration reaches 2.7%, the humidity is reduced by 4-20 g / m3 and improve the air volume by 50m 3 / min dilute coal gas, when the H2 concentration is reduced to 2.4%, the humidification amount is restored to 25g / m 3 .

[0011] Further, the target coal gas utilization rate is >47%.

[0012] Compared with the prior art, the advantages of the present application are: 1. After the implementation of the present application, the theoretical combustion temperature can be stabilized at 2150±10℃, the qualified rate of [Si] content in molten iron is increased to 95%, the upper limit of air volume is increased from 4300m 3 / min to 4600m 3 / min, the daily average output is increased by 8%-10%, the coal gas utilization rate is increased from 45% to 48%, and the fuel ratio is decreased by 5kg / t.

[0013] 2. By decomposing the heat-absorbing water in the humidified blast, the theoretical combustion temperature is reduced from 2250℃ to 2150℃, the softening zone is lowered, the generated H2 improves the liquid permeability of the dead material column, and the liquid permeability is increased by 20%-30%; the reduction rate of H2 is 5-8 times that of CO, which compensates for the insufficient reduction caused by the decrease of coal injection amount. DETAILED DESCRIPTION

[0014] The present application will be further described in detail through specific embodiments: A method for humidifying blast operation during the blowing of a blast furnace, comprising the following steps: S1: initial parameter setting The reference air volume is set to 4300m 3 / min, the blast temperature is 1150℃, the coal injection amount is 70kg / t; the initial value of the humidification amount is 10g / m 3 , the H2 concentration warning threshold of the top gas is set to 2.8%; the theoretical combustion temperature is controlled to be 2150℃, the [Si] content in molten iron is controlled to be 0.4-0.6%, and the physical heat is ≥1480℃.

[0015] S2: stepwise humidification and blast temperature compensation The humidification amount is increased by 5g / m 3 every 30 minutes until the target value of 30g / m 3 is reached, the increase gradient of the humidification amount is 10→15→20→25→30g / m 3 ; the humidification amount is increased by 10g / m 3 , and the blast temperature is increased by 30-50℃ simultaneously, and the coal injection amount is controlled to be 60-80kg / t; S3: real-time monitoring of key parameters Gas flow distribution: real-time monitoring of center and edge CO2% by infrared imager, ensuring that the center CO2% is <19.5% and the edge CO2% is >24.3%; Furnace hearth thermal state: every 15 minutes, detect the [Si] content of molten iron and physical heat, if the [Si] content of molten iron is <0.3% for 2 consecutive heats, reduce the humidification amount by 10g / m 3 ; Hydrogen explosion prevention and control: online gas chromatograph monitors H2 concentration, when H2 concentration reaches 2.7%, reduce the humidification amount by 4-20g / m 3 , and increase the air volume by 50m 3 / min to dilute the coal gas, when H2 concentration decreases to 2.4%, restore the humidification amount to 25g / m 3 ; if H2 concentration exceeds 2.8%, trigger an alarm and suspend humidification; S4: Abnormal condition handling Pressure difference jumps: immediately reduce the air volume to 4000m 3 / min, restore the humidification amount to 15g / m 3 , and add 2 batches of clean coke, each batch is 5 tons, the corresponding index of pressure difference jump is ΔP>180kPa; Low furnace temperature: increase the air temperature by 50℃, increase the coal injection amount by 5kg / t, reduce the humidification amount by 5g / m 3 , the corresponding index of low furnace temperature is [Si] content of molten iron <0.3%; Center airflow occlusion: adjust the distribution matrix, increase the coke distribution angle from 35° to 40°, and reduce the ore distribution angle from 30° to 25°; S5: Steady-state optimization Stable humidification amount at 30g / m 3 , adjust the air temperature by ±10℃ every 2 hours, maintain the [Si] content of molten iron at 0.4-0.6%, adjust the oxygen enrichment amount according to the target coal gas utilization rate, every change of 1% of oxygen enrichment amount corresponds to air volume ±50m 3 / min, target coal gas utilization rate >47%.

[0016] The specific implementation of the above method when the blast furnace of Bayi Steel is started is as follows: S1: Initial parameter setting: set the air volume to 4300m 3 / min, air temperature 1150℃, coal injection amount 70kg / t, humidification amount 10g / m 3 ; the initial value of center CO2% monitored by infrared imager is 20.1%, the initial value of edge CO2% is 23.8%, and the pressure difference ΔP is 165kPa.

[0017] S2: Stepwise humidification and air temperature compensation: after 30 minutes of stepwise humidification, the humidification amount is increased to 15g / m 3, the wind temperature compensation is 1180℃, and the humidification amount is 20g / m 3 , the wind temperature compensation is 1220℃, and the coal injection amount is reduced to 65kg / t.

[0018] S3: Real-time monitoring of key parameters: the humidification amount is increased to 20g / m 3 , the monitoring shows that the [Si] content of the molten iron is 0.45%, the H2concentration is 2.1%, and the pressure difference ΔP is stabilized at 170kPa.

[0019] S4: Abnormal condition treatment When the humidification amount is increased to 25g / m 3 , the pressure difference ΔP suddenly rises to 182kPa, at which time the wind reduction mechanism is triggered, and the wind is immediately reduced to 4000m 3 / min, the humidification amount is adjusted back to 15g / m 3 , and two batches of clean coke are added; 30 minutes later, the pressure difference ΔP falls back to 168kPa, and the wind amount is gradually restored to 4300m 3 / min.

[0020] S5: Steady-state optimization: according to the above steps, the humidification amount is increased to 30g / m 3 , the wind temperature is 1250℃, and the coal injection amount is 60kg / t; when the humidification amount is increased to 30g / m 3 , the monitoring shows that the center CO2% is 18.9%, the edge CO2% is 24.5%, and the [Si] content of the molten iron is 0.52%.

[0021] After the blast furnace of Bayi Steel is implemented according to the above embodiment, the qualified rate of the [Si] content of the molten iron is increased to 95%; the daily average output is increased by 8%-10%; the coal gas utilization rate is increased from 45% to 48%, and the fuel ratio is decreased by 5kg / t.

[0022] The above is only an embodiment of the present application, and the specific structure and characteristics of the scheme and other common knowledge are not described in detail. It should be noted 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, and these will not affect the effect and practicality of the present application. The protection scope claimed in the present 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 humidifying and blasting air during blast furnace start-up, characterized in that, Includes the following steps: S1: Initial parameter settings The baseline air volume is set at 4300 m³ / h. 3 / min, air temperature 1150℃, pulverized coal injection rate 70kg / t; initial humidification rate 10g / m³ 3 The warning threshold for H2 concentration in the furnace top gas is set at 2.8%; the theoretical combustion temperature is controlled at 2150℃; the [Si] content in molten iron is controlled at 0.4-0.6%; and the physical heat is ≥1480℃. S2: Stepped humidification and air temperature compensation Increase the humidification rate by 5g / m³ every 30 minutes. 3 Until the target value of 30g / m³ is reached. 3 For every 10g / m 3 Humidification capacity, simultaneously increase air temperature by 30-50℃; S3: Real-time monitoring of key parameters Airflow distribution: CO2 at the center and edge is monitored in real time using an infrared imager to ensure that CO2% at the center is <19.5% and CO2% at the edge is >24.3%; Hearth thermal status: The [Si] content and physical heat of molten iron are checked every 15 minutes. If the [Si] content of molten iron is <0.3% for two consecutive furnaces, the humidification amount is reduced by 10g / m³. 3 ; Hydrogen explosion prevention: The online gas chromatograph monitors the H2 concentration, and triggers an alarm and suspends humidification when it exceeds 2.8%; S4: Steady-state optimization The humidification rate remained stable at 30g / m³ 3 Afterwards, the air temperature is finely adjusted by ±10℃ every 2 hours to maintain the iron [Si] content at 0.4-0.6%.

2. The method for humidifying and blowing air during blast furnace start-up according to claim 1, characterized in that, In step S2, the humidification amount increases in a gradient of 10→15→20→25→30 g / m³. 3 .

3. The method for humidifying and blowing air during blast furnace start-up according to claim 1, characterized in that, The amount of pulverized coal injected in step S2 is controlled at 60-80 kg / t.

4. The method for humidifying and blowing air during blast furnace start-up according to claim 1, characterized in that, It also includes abnormal operating condition handling procedures, as follows: Sudden increase in pressure differential: Immediately reduce airflow to 4000m 3 / min, humidification rate adjusted back to 15g / m 3 Two batches of clean coke were added, each batch consisting of 5 tons; Furnace temperature too low: Increase blast temperature by 50°C, increase pulverized coal injection by 5 kg / t, and decrease humidification by 5 g / m³. 3 ; Central airflow blockage: Adjust the fabric distribution matrix, increasing the coke distribution angle from 35° to 40° and decreasing the ore distribution angle from 30° to 25°.

5. The method for humidifying and blowing air during blast furnace start-up according to claim 1, characterized in that, In step S4, the oxygen enrichment is adjusted according to the target gas utilization rate. Each 1% change in oxygen enrichment corresponds to an air volume of ±50m³. 3 / min.

6. The method for humidifying and blowing air during blast furnace start-up according to claim 4, characterized in that, The indicator corresponding to the sudden increase in pressure difference is ΔP>180kPa, and the indicator corresponding to the excessively low furnace temperature is the [Si] content in the molten iron <0.3%.

7. The method for humidifying and blowing air during blast furnace start-up according to claim 1, characterized in that, In step S3, when the H2 concentration reaches 2.7%, the humidification dosage is reduced by 4-20 g / m³. 3 And increase the air volume by 50m³ 3 The humidification rate was increased to 25 g / m³ when the H₂ concentration dropped to 2.4%. 3 .

8. The method for humidifying and blowing air during blast furnace start-up according to claim 5, characterized in that, The target gas utilization rate is >47%.