Method for operating a blast furnace with low blast humidity

Abstract

The application discloses a blast furnace low-blast humidity operation method, and aims to solve the technical problems of lacking system regulation scheme for low-blast humidity smelting, easy loss of control of furnace condition, difficult balance between dehumidification energy consumption and fuel saving benefits, and large fluctuation range of furnace temperature. 3 The low-humidity stable smelting is realized through hierarchical regulation, the atmospheric humidity and blast volume of the blast furnace are detected in real time, the blast humidity after dehumidification is stably controlled in the range of 3-8 g / m 3 The theoretical combustion temperature of the tuyere corresponding to the blast humidity of 8 g / m The amount of sprayed coal is dynamically adjusted according to the humidity deviation, and the theoretical combustion temperature is maintained stable; the coal coke conversion coefficient is determined in combination with the silicon content of the molten iron, the amount of coke into the blast furnace is adjusted correspondingly to balance the heat of the hearth, and the time difference of the thermal effects of the sprayed coal and the coke is offset by the pre-reduction amount of the coke. The application can guarantee the smooth operation of the blast furnace under the low-humidity condition, effectively reduce the coke ratio into the blast furnace and the comprehensive smelting cost, reduce the fluctuation of the furnace temperature, and improve the stability of the molten iron quality.

Description

Technical Field

[0001] This invention relates to the field of blast furnace smelting technology, and more specifically, to a method for operating a blast furnace with low blast humidity. Background Technology

[0002] In the blast furnace smelting process, the blower draws in ambient air, heats it into high-temperature hot air via a hot blast stove, and then sends it into the blast furnace hearth. This provides the necessary oxidizing atmosphere and heat for coke combustion and iron ore melting and reduction. Blast air humidity is one of the core process parameters affecting blast furnace temperature, fuel consumption, and furnace operation. In existing technologies, blast furnace blast is classified into three categories based on humidity control methods: humidified blast, dehumidified blast, and natural blast. When the ambient humidity is low, steam is added to the blast to increase humidity, which is called humidified blast. When the ambient humidity is high, moisture is removed from the blast to reduce humidity, which is called dehumidified blast. When the ambient humidity is suitable for smelting requirements, uncontrolled natural blast is used directly.

[0003] In current blast furnace production both domestically and internationally, the humidity of the blast air is typically controlled at 8–12 g / m³. 3 Within this range, the mainstream operating level remains at 10g / m 3 Left and right use less than 6g / m 3 The industrial application of low-humidity blower air in smelting is very limited, and the core technical defects are mainly reflected in three aspects: 1. There is a lack of mature and comprehensive furnace condition control methods under low blast humidity conditions. According to the thermodynamic laws of blast furnace smelting, for every 1 g / m³ decrease in blast humidity... 3 The theoretical combustion temperature at the tuyeres increases by approximately 9°C. Under low humidity conditions, the theoretical combustion temperature rises significantly. If timely adjustment measures are not implemented, it can easily lead to abnormalities such as furnace heat accumulation and increased hot blast pressure, disrupting the smooth operation of the blast furnace. However, the industry has not yet established a systematic low-humidity furnace temperature balancing operation system, which directly restricts the large-scale application of low-humidity coke reduction technology.

[0004] 2. The dehumidification control method is crude, and the energy consumption cost and fuel benefits cannot be quantitatively balanced. Current dehumidification operations rely heavily on manual adjustments based on operator experience, without establishing a quantitative correlation between dehumidification power consumption and fuel consumption reduction. This makes it impossible to optimize the number of dehumidification units and their operating power while maintaining a stable low humidity target. As a result, problems such as over-dehumidification and low unit operating efficiency often occur, leading to excessively high dehumidification power costs that offset the fuel savings brought by low humidity, resulting in insufficient motivation for enterprises to adopt this method.

[0005] 3. Insufficient multi-parameter coupling and control capability, making it difficult to effectively control furnace temperature fluctuations. Under low blast humidity conditions, there are complex coupling relationships between blast humidity, theoretical combustion temperature at the tuyeres, hearth heat level, and furnace operation status; simultaneously, the reaction processes of injected pulverized coal and coke in the furnace differ, resulting in a significant time difference in thermal effects. Existing operating methods cannot achieve dynamic linkage and balance of multiple parameters, easily causing frequent furnace temperature fluctuations, which in turn affect the stability of molten iron composition and quality. Summary of the Invention

[0006] The low blast humidity operation method for blast furnaces provided by this invention aims to solve the following problems: In existing technologies, low blast humidity smelting suffers from a lack of systematic operation methods, easy loss of furnace control, difficulty in balancing dehumidification energy consumption and fuel savings, and large furnace temperature fluctuations. This invention provides a low blast humidity operation method for blast furnaces, achieving a humidity level of 3–8 g / m³. 3 Within the low blast humidity range, the goal of optimizing dehumidification energy consumption, achieving dynamic balance of furnace temperature, and ensuring stable furnace operation is achieved, thereby realizing the blast furnace smelting objective of low coke ratio and low cost.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The low-humidity operation method for blast furnace blast air includes the following steps: S1. Blast Air Humidity Range Control: Real-time monitoring of atmospheric humidity and blast furnace blast volume to ensure that the blast air humidity after dehumidification is between 3 and 8 g / m³. 3 The target range is defined by calculating the amount of water to be removed per unit time. Based on this target, the number and frequency of dehumidifier units are adjusted to maintain the humidity of the blower air at 3–8 g / m³. 3 Within the range; S2. Theoretical combustion temperature balance adjustment at the air outlet: with a blower humidity of 8g / m³ 3 The theoretical combustion temperature of the tuyere is the reference temperature. The reference coal injection amount is set accordingly. The humidity of the blast air after dehumidification is detected in real time. The change in the theoretical combustion temperature of the tuyere is calculated based on the deviation between the blast air humidity and the reference humidity. The coal injection amount of the blast furnace is adjusted according to the temperature change to keep the theoretical combustion temperature of the tuyere at the reference temperature level. S3. Hearth heat balance adjustment: Determine the coke conversion coefficient based on the current silicon content of molten iron, and adjust the amount of coke fed into the furnace accordingly in combination with the adjustment of the amount of pulverized coal injected, so as to balance the total heat of the blast furnace hearth.

[0008] Furthermore, in step S1, the method for calculating the amount of water to be removed per unit time is as follows: In the formula, M is the blast furnace air volume, and β is the atmospheric humidity.

[0009] Furthermore, in step S1, the humidity of the blower is detected at the outlet of the dehumidifier unit and on the pipeline before the cold air enters the hot air furnace, and the humidity detection cycle is 1 minute / time. The dehumidifier unit has at least three operating frequency settings, with a frequency difference of 5Hz between adjacent settings; When the atmospheric humidity is higher than 8g / m 3 The dehumidifier unit automatically starts dehumidification; when the humidity of the blower air is below 3g / m³ after dehumidification... 3 At the same time, gradually reduce the operating frequency of each dehumidifier unit until the blower air humidity rises back to 3-8 g / m³. 3 The range is when the atmospheric humidity is below 3g / m³. 3 At that time, the dehumidifier unit stops operating.

[0010] Furthermore, in step S2, the calculation process for the adjustment of the pulverized coal injection amount is as follows: In the formula, ∆Y is the adjustment amount of the pulverized coal quantity, ∆T is the change in the theoretical combustion temperature of the tuyere, and A is the change in the theoretical combustion temperature of the tuyere corresponding to a change of 1t / h in the pulverized coal quantity.

[0011] Furthermore, the calculation process for the theoretical combustion temperature change ∆T at the vent is as follows: In the formula, β1 is the humidity of the hot air entering the blast furnace, and B is the value of the blast humidity decreasing by 1 g / m³. 3 The theoretical combustion temperature rise at the air vent.

[0012] Furthermore, the adjustment triggering cycle of step S2 is 10 to 20 minutes. That is, after the blast humidity changes, the pulverized coal quantity adjustment operation is performed after an interval of 10 to 20 minutes until the theoretical combustion temperature stabilizes.

[0013] Furthermore, in step S3, the value of the coal-coke conversion factor ranges from 0.8% to 1.0%. The coal-coke conversion factor is linearly positively correlated with the silicon content of molten iron. The higher the silicon content of molten iron, the larger the value of the coal-coke conversion factor.

[0014] Furthermore, in step S3, 5 to 7 hours before the pulverized coal injection quantity adjustment is performed, the amount of coke fed into the furnace is pre-reduced to offset the time difference in the thermal effect of the pulverized coal and coke reacting in the blast furnace.

[0015] Furthermore, the calculation method for pre-reduction adjustment is as follows: based on 3–8 g / m³. 3 The maximum pulverized coal adjustment amount corresponding to the humidity range is used as the base, and the hourly coke pre-reduction amount is calculated according to the minimum coal-coke conversion factor.

[0016] Furthermore, when an abnormal furnace condition occurs, the automatic adjustment process is stopped and switched to manual control mode; abnormal furnace conditions include blast furnace shutdown, prolonged slow airflow with air volume lower than 70% of normal air volume, production safety accidents or quality accidents.

[0017] The beneficial effects of this invention are as follows: This invention precisely controls the humidity of the blower air to 3-8 g / m³. 3In the low range, a tiered operation system is constructed to control humidity range, balance theoretical combustion temperature, and adjust hearth heat in conjunction with the system. This solves the industry pain point that excessively high theoretical combustion temperature at the tuyeres under low blast humidity can easily lead to furnace condition disturbances. It provides a stable and implementable operation solution for low coke ratio smelting and expands the application boundaries of blast furnace blast humidity.

[0018] This invention, by quantitatively calculating the amount of water removed per unit time and combining it with adaptive adjustment of the number of dehumidifier units in operation and frequency settings, minimizes dehumidification power consumption while ensuring the target humidity range. It establishes a quantitative balance between dehumidification energy consumption and fuel saving, leveraging the cost advantage of low humidity coke reduction while avoiding energy waste from excessive dehumidification, thus optimizing overall smelting costs.

[0019] This invention uses the silicon content of molten iron as the basis for judging the heat of the hearth, and dynamically adjusts the coke conversion factor to ensure that the amount of coke added to the furnace is precisely matched with the actual thermal state of the hearth. This replaces the traditional crude adjustment method with a fixed conversion factor, effectively reducing the range of furnace temperature fluctuations and improving the stability of molten iron composition and quality.

[0020] This invention addresses the time difference in the thermal effects of pulverized coal injection and coke in the furnace by employing a pre-reduction mechanism for coke to offset the time misalignment of their thermal effects. This prevents significant fluctuations in furnace temperature, which initially rises and then falls, further improving the smooth operation of the blast furnace under low humidity conditions. It is adaptable to atmospheric humidity fluctuations in different seasons and regions. Detailed Implementation

[0021] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0022] The following examples all use a volume of 3200m³. 3 The blast furnace is the application target, equipped with three dehumidifier units, each with a rated operating power of 2200 kWh. The dehumidifier units have three operating frequency settings: high, medium, and low, at 48 Hz, 43 Hz, and 38 Hz respectively, with a frequency difference of 5 Hz between adjacent settings. The blast furnace's baseline smelting parameters are: blast humidity 8 g / m³. 3 At that time, the theoretical combustion temperature at the tuyeres was 2280℃, corresponding to a benchmark pulverized coal injection rate of 50t / h, and the silicon content of the molten iron was conventionally controlled within the range of 0.3% to 0.5%.

[0023] Example 1

[0024] This embodiment is designed for production scenarios with high atmospheric humidity in summer, where the ambient atmospheric humidity fluctuates between 14 and 18 g / m³. 3The normal blast furnace blast volume is 6000 m³ / h. 3 / min, the specific operation process is as follows: First, control the humidity range of the blast furnace blast. Real-time monitoring of atmospheric humidity and blast furnace blast volume is implemented. Humidity sensors are located at the outlet of the dehumidifier unit and on the pipeline before the cold air enters the hot blast stove, with a monitoring cycle of 1 minute. The goal is to stabilize the blast furnace humidity at 3–8 g / m³ after dehumidification. 3 To control the target, calculate the amount of water to be removed per unit time. The formula for calculating the hourly water removal capacity is as follows: In the formula, M is the blast furnace air volume, and β is the atmospheric humidity.

[0025] This model can be used to calculate the required humidity level to be removed from the blower under different humidity conditions. For example, when the atmospheric humidity is 14 g / m³... 3 Therefore, the blower needs to remove at least 6g / m³ of air. 3 Only water of sufficient quality can meet the requirements of low-humidity smelting, so the amount of water removed from the blower per hour... Based on the calculated dehydration requirements, two dehumidifier units were started. One unit maintained a high frequency of 48Hz, while the other dynamically adjusted its operating speed across three levels according to real-time atmospheric humidity fluctuations. When atmospheric humidity increased, the operating speed was increased to enhance dehydration capacity; when the humidity of the blower air after dehydration was below 3g / m³, the dehumidifier was activated. 3 At the same time, gradually reduce the operating frequency of each dehumidifier unit until the blower air humidity rises back to 3-8 g / m³. 3 The range is when the atmospheric humidity is below 3g / m³. 3 When this occurs, the dehumidifier unit stops operating. Under this condition, the humidity of the dehumidifier blower air stabilizes at 5–7 g / m³ after adjustment. 3 The average humidity of the blower air in this range is approximately 5.5 g / m³. 3 .

[0026] Then, the theoretical combustion temperature balance at the air vent was adjusted. The blower humidity was set at 8 g / m³. 3 The corresponding theoretical combustion temperature of 2280℃ is taken as the benchmark temperature, and the corresponding benchmark pulverized coal injection rate is 50t / h. According to the thermodynamic laws of blast furnace smelting, for every 1g / m³ decrease in blast humidity... 3 The theoretical combustion temperature at the tuyere increases by 9°C. For every 1t / h change in the amount of pulverized coal injected, the theoretical combustion temperature at the tuyere changes by 20°C. The adjustment trigger cycle is 10-20 minutes. That is, after the humidity of the blower changes, the pulverized coal injection rate is adjusted only after the theoretical combustion temperature has stabilized at an interval of 10-20 minutes to avoid frequent misadjustments.

[0027] The formula for calculating the adjustment amount of pulverized coal injection is as follows: In the formula, ∆Y is the adjustment amount of the pulverized coal quantity, ∆T is the change in the theoretical combustion temperature of the tuyere, and A is the change in the theoretical combustion temperature of the tuyere corresponding to a change of 1t / h in the pulverized coal quantity.

[0028] The formula for calculating the theoretical combustion temperature change ∆T at the air vent is as follows: In the formula, β1 is the humidity of the hot air entering the blast furnace, and B is the value of the blast humidity decreasing by 1 g / m³. 3 The theoretical combustion temperature rise at the air vent.

[0029] In this embodiment, the pulverized coal injection control standards corresponding to different blower humidity are shown in the table below: Table 1. Control Standards Corresponding to Blower Humidity and Pulverized Coal Injection Rate

[0030] By dynamically adjusting the pulverized coal injection rate, the theoretical combustion temperature at the tuyere can be stably maintained at the benchmark level, avoiding abnormalities such as excessively high theoretical combustion temperature under low humidity conditions, which could lead to furnace heat accumulation and increased hot air pressure.

[0031] Finally, the hearth heat balance is adjusted. After adjusting the pulverized coal injection rate, the coke-coke conversion factor is determined based on the current silicon content of the molten iron. The amount of coke fed into the furnace is then adjusted accordingly, based on the adjustment of the pulverized coal injection rate, to balance the total heat of the blast furnace hearth. The coke-coke conversion factor ranges from 0.8 to 1.0 and is linearly positively correlated with the silicon content of the molten iron: the higher the silicon content, the larger the conversion factor; for every 0.01% decrease in the silicon content of the molten iron, the coke-coke conversion factor decreases by 0.67%. The correspondence between the silicon content of the molten iron and the corresponding conversion factor is shown in the table below: Table 2. Conversion coefficients of molten iron silicon content to coke. 1 0.6 100% 2 0.59 0.9933 3 0.58 0.9866 4 0.57 0.9799 5 0.56 0.9732 6 0.55 0.9665 7 0.54 0.9598 8 0.53 0.9531 9 0.52 0.9464 10 0.5 0.9397 11 0.49 0.933 12 0.48 0.9263 13 0.47 0.9196 14 0.46 0.9129 15 0.45 0.9062 16 0.44 0.8995 17 0.43 0.8928 18 0.42 0.8861 19 0.41 0.8794 20 0.4 0.8727 21 0.39 0.866 22 0.38 0.8593 23 0.37 0.8526 24 0.36 0.8459 25 0.35 0.8392 26 0.34 0.8325 27 0.33 0.8258 28 0.32 0.8191 29 0.31 0.8124 30 0.3 0.8057 Meanwhile, to offset the time difference in the thermal effects of the reaction between pulverized coal and coke in the blast furnace, the amount of coke fed into the furnace is pre-reduced 5-7 hours before the pulverized coal injection rate adjustment. The pre-reduction is 3-8 g / m³. 3 The maximum pulverized coal adjustment amount corresponding to the humidity range is used as the base, and the hourly coke pre-reduction amount is calculated based on the minimum coal-coke conversion factor; the maximum humidity fluctuation under this operating condition is 5g / m³. 3 The corresponding maximum pulverized coal injection adjustment is 2.25 t / h. Calculated using a conversion factor of 0.8%, the pre-reduction of coke is 1.8 tons per hour.

[0032] Under the operating conditions of this embodiment, the blast furnace operates stably and smoothly, the coke ratio is reduced to 325 kg / t, the blast furnace coal ratio is increased to 180 kg / t, the furnace temperature fluctuation is significantly reduced, and the stability of the silicon content in molten iron is significantly improved.

[0033] Example 2 This embodiment is designed for production scenarios with low atmospheric humidity in winter, where the ambient atmospheric humidity fluctuates between 2 and 6 g / m³. 3 The blast furnace blast volume and the benchmark smelting parameters are consistent with those in Example 1. The specific operation process is as follows: When controlling the humidity range of the blower, the atmospheric humidity is monitored in real time; when the atmospheric humidity is below 3g / m³ 3 When the humidity is between 3 and 8 g / m³, the dehumidifier unit stops operating and natural ventilation is used; 3 During this period, the dehumidifier unit remains in standby mode and requires no additional dehumidification treatment. Under this operating condition, the blower air humidity naturally ranges from 3 to 6 g / m³. 3 The range is 3-8 g / m³. 3 The goal of low humidity control can be achieved by smelting with low humidity without consuming dehumidification power.

[0034] When adjusting the theoretical combustion temperature balance at the air vent, the same applies to the blower air humidity of 8g / m³. 3 Based on a theoretical combustion temperature of 2280℃ and a pulverized coal injection rate of 50t / h, the change in theoretical combustion temperature is calculated according to humidity deviation, and the pulverized coal injection rate is adjusted accordingly. The adjustment trigger cycle is 10-20 minutes, and the adjustment is performed after the theoretical combustion temperature stabilizes. Under this operating condition, the overall humidity of the blower is relatively low, so the pulverized coal injection rate is reduced accordingly to maintain the theoretical combustion temperature at the tuyeres at the benchmark level.

[0035] When adjusting the hearth heat balance, the corresponding coal-coke conversion factor is selected based on the real-time detected silicon content of the molten iron, and the amount of coke fed into the furnace is reduced accordingly based on the pulverized coal injection adjustment. At the same time, a coke pre-reduction operation is performed 5 to 7 hours in advance to offset the time difference in the thermal effects of pulverized coal injection and coke, ensuring a smooth transition of hearth heat and avoiding large fluctuations in furnace temperature.

[0036] Under the operating conditions of this embodiment, the dehumidification unit has extremely low energy consumption, further reducing the overall smelting cost, maintaining stable and smooth furnace operation, and the fuel consumption index is significantly better than the conventional humidity operation level.

[0037] Comparative Example This comparative example adopts the industry-standard blast furnace operation method, with the blast humidity controlled at 8–12 g / m³. 3 The average humidity is approximately 10 g / m³. 3 The method relied on operators' experience to manually adjust the pulverized coal and coke quantities, without employing precise humidity range control and multi-parameter linkage adjustment mechanisms. Compared to the above embodiments, the theoretical combustion temperature of the blast furnace tuyeres in this comparative example fluctuates significantly with atmospheric humidity, with the furnace temperature fluctuation range being approximately twice that of the embodiments; the coke ratio is approximately 360 kg / t, and the coal ratio is approximately 150 kg / t, resulting in significantly higher fuel consumption than the method of this invention; simultaneously, atmospheric humidity fluctuations easily lead to furnace condition fluctuations, resulting in poor blast furnace operational stability, large fluctuations in the silicon content of molten iron, and insufficient quality stability.

[0038] When abnormal furnace conditions occur, including blast furnace shutdown, prolonged slow blast with air volume below 70% of normal air volume, production safety accidents, or quality accidents, the above automatic adjustment process shall be stopped and switched to manual control mode; the low blast humidity operation method of this invention shall not be implemented during the blast furnace start-up and shutdown phases.

[0039] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for operating a blast furnace with low blast humidity, characterized in that, Includes the following steps: S1. Blast Air Humidity Range Control: Real-time monitoring of atmospheric humidity and blast furnace blast volume to ensure that the blast air humidity after dehumidification is between 3 and 8 g / m³. 3 The target range is defined by calculating the amount of water to be removed per unit time. Based on the required water removal volume, the number and frequency of the dehumidifier units are adjusted to stabilize the humidity of the blower air after dehumidification at 3–8 g / m³. 3 Within the range; S2. Theoretical combustion temperature balance adjustment at the air outlet: with a blower humidity of 8g / m³ 3 The theoretical combustion temperature of the tuyere is the reference temperature. The reference coal injection amount is set accordingly. The humidity of the blast air after dehumidification is detected in real time. The change in the theoretical combustion temperature of the tuyere is calculated based on the deviation between the blast air humidity and the reference humidity. The coal injection amount of the blast furnace is adjusted according to the temperature change to keep the theoretical combustion temperature of the tuyere at the reference temperature level. S3. Hearth heat balance adjustment: Determine the coke conversion coefficient based on the current silicon content of molten iron, and adjust the amount of coke fed into the furnace accordingly in combination with the adjustment of the amount of pulverized coal injected, so as to balance the total heat of the blast furnace hearth.

2. The blast furnace low blast humidity operation method according to claim 1, characterized in that: In step S1, the calculation method for the amount of water to be removed per unit time is as follows: In the formula, M is the blast furnace air volume, and β is the atmospheric humidity.

3. The blast furnace low blast humidity operation method according to claim 1, characterized in that: In step S1, the humidity of the blower is detected at the outlet of the dehumidifier unit and on the pipeline before the cold air enters the hot air furnace. The humidity detection cycle is 1 minute / time. The dehumidifier unit has at least three operating frequency settings, with a frequency difference of 5Hz between adjacent settings; When the atmospheric humidity is higher than 8g / m 3 The dehumidifier unit automatically starts dehumidification; when the humidity of the blower air is below 3g / m³ after dehumidification... 3 At the same time, gradually reduce the operating frequency of each dehumidifier unit until the blower air humidity rises back to 3-8 g / m³. 3 The range is when the atmospheric humidity is below 3g / m³. 3 At that time, the dehumidifier unit stops operating.

4. The blast furnace low blast humidity operation method according to claim 1, characterized in that: In step S2, the calculation process for the adjustment of the pulverized coal injection amount is as follows: In the formula, ∆Y is the adjustment amount of the pulverized coal quantity, ∆T is the change in the theoretical combustion temperature of the tuyere, and A is the change in the theoretical combustion temperature of the tuyere corresponding to a change of 1t / h in the pulverized coal quantity.

5. The blast furnace low blast humidity operation method according to claim 4, characterized in that: The calculation process for the theoretical combustion temperature change ∆T at the air outlet is as follows: In the formula, β1 is the humidity of the hot air entering the blast furnace, and B is the value of the blast humidity decreasing by 1 g / m³. 3 The theoretical combustion temperature rise at the air vent.

6. The blast furnace low blast humidity operation method according to claim 1, characterized in that: The adjustment triggering cycle of step S2 is 10 to 20 minutes. That is, after the humidity of the blower changes, the pulverized coal quantity adjustment operation is performed after an interval of 10 to 20 minutes until the theoretical combustion temperature stabilizes.

7. The blast furnace low blast humidity operation method according to claim 1, characterized in that: In step S3, the value of the coal-coke conversion factor ranges from 0.8% to 1.0%. The coal-coke conversion factor is linearly positively correlated with the silicon content of molten iron. The higher the silicon content of molten iron, the larger the value of the coal-coke conversion factor.

8. The blast furnace low blast humidity operation method according to claim 1, characterized in that: In step S3, 5 to 7 hours before the pulverized coal injection quantity adjustment, the amount of coke fed into the furnace is pre-reduced to offset the time difference in the thermal effect of the pulverized coal and coke reaction in the blast furnace.

9. The blast furnace low blast humidity operation method according to claim 8, characterized in that, The calculation method for the pre-reduction adjustment is as follows: based on 3-8 g / m³. 3 The maximum pulverized coal adjustment amount corresponding to the humidity range is used as the base, and the hourly coke pre-reduction amount is calculated according to the minimum coal-coke conversion factor.

10. The blast furnace low blast humidity operation method according to claim 1, characterized in that: When an abnormal furnace condition occurs, the automatic adjustment process is stopped and the manual control mode is switched. The abnormal furnace condition includes blast furnace shutdown, prolonged slow air flow with air volume lower than 70% of the normal air volume, production safety accidents or quality accidents.

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