A method for stable and safe control of an automatic pulverized coal injection system in a blast furnace

Abstract

This invention discloses a safety protection control method for an automatic pulverized coal injection control system, belonging to the blast furnace ironmaking technology field within the iron and steel metallurgy industry. Addressing the problems of large coal quantity fluctuations, lack of safety limits, and poor fuel ratio linkage in existing blast furnace pulverized coal injection control technologies, this invention employs a triple-limit protection logic for pulverized coal injection quantity (single adjustment amplitude constraint, upper and lower limit locking, and fuel ratio linkage): single coal quantity addition / reduction is controlled by default within Δm; upper and lower safety limits for pulverized coal injection quantity are protected; and the fuel ratio is calculated based on the process control fuel ratio constraint for pulverized coal injection quantity. This invention effectively reduces single pulverized coal injection quantity fluctuations, improves pulverized coal injection stability and equipment safety, adapts to different furnace conditions, optimizes energy consumption costs, and ensures long-term stable and efficient operation of the blast furnace.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking technology in the iron and steel metallurgy industry, specifically to a stable and safe control method for an automatic pulverized coal injection system in a blast furnace. It is applicable to the scenario of precise control of coal quantity fluctuations during pulverized coal injection in a blast furnace, and can coordinate the adjustment of pulverized coal quantity, safety limits and fuel ratio linkage to ultimately ensure the thermal balance and stable operation of the blast furnace. It is especially suitable for pulverized coal injection systems of blast furnaces of different scales and furnace conditions. Background Technology

[0002] In blast furnace ironmaking, the pulverized coal injection system is the core link for reducing coke ratio, saving energy and improving economic efficiency. The stability of pulverized coal injection directly determines the furnace heat balance, molten iron quality and production safety. The current blast furnace pulverized coal injection control technology in the industry has the following key pain points: (1) Large fluctuation range of coal quantity: Existing technologies mostly rely on manual experience or simple algorithms to adjust the pulverized coal quantity, without setting clear limits on the single addition or subtraction of coal quantity. It is easy to cause sudden changes in coal quantity due to misjudgment of furnace conditions (such as a single adjustment range exceeding 2t / h), which in turn causes drastic fluctuations in furnace temperature and affects the quality of molten iron; (2) Lack of safety upper and lower limit protection for pulverized coal quantity: Affected by factors such as sensor failure and data transmission interruption, the pulverized coal quantity is prone to zeroing (coal stoppage) or exceeding the equipment load limit (such as exceeding 90t / h). Among them, stopping coal will cause the furnace to cool down, requiring emergency coking to maintain the furnace condition, which significantly increases production costs; exceeding the upper limit will cause incomplete combustion of pulverized coal, producing a large amount of unburned pulverized coal, which may cause a suspension accident and threaten production safety; (3) Poor linkage between fuel ratio and pulverized coal injection: In the existing technology, fuel ratio control is mostly independent of pulverized coal injection adjustment, and a closed-loop linkage mechanism between the two has not been established. When the fuel ratio exceeds the process requirement range (such as below 500 kg / t.Fe or above 520 kg / t.Fe), the pulverized coal injection is still adjusted according to the original logic, resulting in fuel ratio out of control and further aggravating furnace heat fluctuations; the currently disclosed related technologies do not involve single adjustment range limits, pulverized coal injection upper and lower limit protection and fuel ratio linkage constraints, which cannot fundamentally solve the problem of coal quantity fluctuations, and still have significant production safety hazards and energy waste.

[0003] In view of the problems of easy fluctuation in coal quantity, lack of safety limit, poor linkage of fuel ratio and insufficient monitoring and emergency response in the existing blast furnace pulverized coal injection control technology, the present invention aims to provide a method for stable control of blast furnace pulverized coal injection quantity with multi-level limit protection. The specific objectives include: (1) to achieve precise constraint on the single adjustment range of pulverized coal injection quantity, control the single addition or subtraction of coal quantity within the set range, and avoid furnace temperature fluctuation caused by sudden changes in coal quantity; (2) to set safe upper and lower limits for pulverized coal injection quantity, eliminate the risk of coal shutdown and overload operation of equipment, and ensure production safety; (3) to establish a closed-loop linkage mechanism between fuel ratio and pulverized coal injection quantity, and ensure that the fuel ratio meets the process requirements by constraining the calculation of pulverized coal injection quantity through the upper and lower limits of fuel ratio; (4) to finally reduce the fluctuation range of single pulverized coal injection quantity, achieve stable silicon reduction, and ensure long-term stable and efficient operation of blast furnace. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by providing a stable and safe control method for an automatic pulverized coal injection system in a blast furnace.

[0005] The purpose of this invention is achieved as follows: a stable and safe control method for an automatic pulverized coal injection system in a blast furnace, comprising the following aspects: (1) First protection: limit on the maximum amount of coal added or subtracted at one time: 1) The control module calculates the "theoretical recommended amount of pulverized coal injection" M1 every 10 minutes and compares it with the current actual amount of pulverized coal injection M0; sets the maximum amount of coal added or subtracted at one time △m, with a value range of 0.3-1.5; 2) If |M1-M0|>△m, the execution module automatically adjusts the amount of pulverized coal injection according to "M=M0±△m", taking "+" for adding coal and "-" for subtracting coal; 3) The user can modify the upper limit of the single adjustment range △m through the "Parameter Setting → Furnace Thermal Closed-Loop Parameter Setting" interface of the monitoring module to adapt to different furnace conditions; (2) Second protection: upper and lower limit locking of pulverized coal injection: 1) when the lower limit is triggered: if the "theoretical recommended amount of pulverized coal injection" < the lower limit coal injection setting value m 下限 The control module forces the use of m 下限 1) Coal injection command to prevent the primary control system from shutting down coal production due to excessively low coal quantity settings; 2) When the upper limit is triggered: if "theoretical recommended coal injection quantity" > upper limit coal quantity setting value m 上限 The control module forces the use of m 上限 The coal injection command, the monitoring module prompts "coal injection quantity exceeds the upper limit, fuel ratio needs to be checked" on the "furnace condition diagnosis → coal injection early warning analysis" interface; (3) Third protection: fuel ratio and coal injection quantity linkage constraint: 1) Based on "fuel ratio = coke ratio + coal ratio", collect the control coke ratio CR, and calculate the target coal injection quantity by "control coal ratio = fuel ratio - CR"; 2) When the system recommends fuel ratio < the manually set lower limit fuel ratio, the system recommends fuel ratio control at 480-580kg / tFe, and controls the coal quantity according to the lower limit fuel ratio to ensure that the coal injection quantity is not lower than the lower limit fuel ratio for coal quantity; 3) When the system recommends fuel ratio greater than the manually set upper limit fuel ratio, controls the coal quantity according to the upper limit fuel ratio to ensure that the coal injection quantity is not higher than the upper limit fuel ratio for coal quantity.

[0006] The second layer of protection includes a lower limit coal quantity setting value m. 下限 The capacity is 12-23 t / h, with the upper limit coal limit set at m. 上限 The capacity is 75-95 t / h.

[0007] The beneficial effects of this invention are: (1) Significantly improved coal injection stability: Through triple limit protection, the fluctuation range of coal quantity is reduced from the single unlimited fluctuation of coal quantity in the existing technology to Δm, which solves the problem of furnace temperature fluctuation caused by sudden changes in coal quantity, narrows the fluctuation of iron silicon and temperature measurement, and improves the qualified rate of pig iron; the continuous and stable operation cycle of blast furnace is extended; (2) Improved equipment operation safety: The setting of the upper limit of coal injection quantity avoids incomplete combustion caused by coal quantity exceeding equipment load, and even causes suspension accident; the lower limit and data completion mechanism prevents the risk of coal stoppage caused by sensor failure and reduces the number of emergency coking times; (3) Strong adaptability of furnace heat closed-loop control system: The single adjustment range, upper and lower limits of coal injection quantity, and fuel ratio range can all be customized according to the blast furnace capacity, which is applicable to blast furnaces of different scales and furnace conditions, and has strong versatility; (4) Optimization of energy consumption and cost: Stable and accurate coal injection quantity ensures the accuracy of blast furnace heat control, reduces the problem of abnormal furnace temperature caused by large amount of manual coal adjustment, and is conducive to accurate control of furnace temperature and achieving stable silicon and reduced silicon content.

[0008] Taiyuan Iron & Steel Group's No. 6 blast furnace has an annual output of 3.5 million tons. After the control system was put into use, the Si content in the blast furnace hot metal decreased by 0.08%, and the fuel cost of the blast furnace decreased by 20.78 yuan / tFe (base period is from August 2024 to January 2025, application period is from February 2025 to July 2025). If the contribution rate of this innovative technology is calculated to be 20%, then the annual cost saving = 3.5 million × 20.78 × 0.2 = 14.54 million yuan, which is a significant economic benefit. Detailed Implementation

[0009] This invention addresses the problems of large coal quantity fluctuations, lack of safe upper and lower limits (leading to easy coal shutdowns / overloads), poor fuel ratio linkage, and insufficient monitoring and emergency response in existing blast furnace pulverized coal injection control systems. It innovatively constructs a triple-limit protection system for pulverized coal injection quantity, and key parameters can be customized to adapt to different furnace conditions. After application, the fluctuation of single pulverized coal injection quantity is effectively reduced, eliminating the risks of coal shutdowns and overloads, ensuring fuel ratio compliance, narrowing fluctuations in molten iron silicon / temperature measurement, improving the pass rate, and extending the blast furnace operating cycle. It also reduces emergency coking and hanging accidents, lowering energy consumption; for example, significant annual cost savings have been achieved in Taiyuan Iron & Steel Group's No. 6 blast furnace. Adaptable to blast furnaces of different sizes, it is highly practical and effectively ensures stable and efficient blast furnace operation.

[0010] This invention is applied to the automatic pulverized coal injection control system of blast furnace to achieve stable and safe control of pulverized coal injection quantity. The specific technical solution is as follows: (I) Multi-level boundary protection logic of pulverized coal injection quantity: 1. First protection (a precise constraint mechanism for the single adjustment range of pulverized coal injection quantity): Limitation of the maximum amount of coal added or subtracted at one time: (1) The control module calculates the "theoretical suggested pulverized coal injection quantity" (M1) once every 10 minutes and compares it with the current actual pulverized coal injection quantity (M0); sets the maximum amount of coal added or subtracted at one time △m, with a value range of 0.3-1.5. (2) If |M1-M0|>△m, the execution module automatically adjusts the pulverized coal injection quantity according to "M=M0±△m" (adding coal takes "+", reducing coal takes "-"), and the single adjustment range can be customized within the range of 0.3-1.5t / h; (3) Users can modify the upper limit of the single adjustment range △m through the "parameter setting → furnace heat closed loop parameter setting" interface of the monitoring module to adapt to different furnace conditions.

[0011] 2. Second layer of protection (a safety upper and lower limit locking mechanism for pulverized coal injection): Upper and lower limit locking of pulverized coal injection: (1) When the lower limit is triggered: if "theoretical recommended pulverized coal injection" < lower limit pulverized coal injection setting value m 下限 The control module forces the use of m 下限 (2) When the upper limit is triggered: if the "theoretical recommended coal injection quantity" > the upper limit coal quantity setting value m 上限 The control module forces the use of m 上限 Upon receiving the pulverized coal injection command, the monitoring module displays a message on the "Furnace Condition Diagnosis → Pulverized Coal Injection Early Warning Analysis" interface stating "Pulverized coal injection exceeds the upper limit; fuel ratio needs to be checked." 3. Third layer of protection (a closed-loop mechanism based on fuel ratio constraint): fuel ratio and pulverized coal injection quantity are linked and constrained. The target pulverized coal injection quantity is calculated by constraining the upper and lower limits of fuel ratio to ensure that the fuel ratio meets the process requirements and solve the problem of poor linkage between the two: (1) Based on "fuel ratio = coke ratio + coal ratio", the coke ratio (CR) is collected and controlled, and the target pulverized coal injection quantity is calculated by "controlling coal ratio = fuel ratio - CR"; (2) When the system suggests fuel ratio < the manually set lower limit fuel ratio, the coal quantity is controlled by the lower limit fuel ratio to ensure that the pulverized coal injection quantity is not lower than the lower limit fuel ratio relative to the coal quantity; (3) When the system suggests fuel ratio > the manually set upper limit fuel ratio, the coal quantity is controlled by the upper limit fuel ratio to ensure that the pulverized coal injection quantity is not higher than the upper limit fuel ratio relative to the coal quantity.

[0012] By combining triple boundary protection with full-process monitoring and emergency response, stable control of pulverized coal injection and safe operation of the blast furnace can be achieved. Example 1

[0013] Taking Taiyuan Iron & Steel Group's No. 6 blast furnace as the implementation object, the blast furnace pulverized coal injection control method of the present invention is applied. The specific steps are as follows: (1) Preliminary preparation: Select the stable operation period of the blast furnace. During this period, the silicon content of the molten iron is 0.4-0.5%, the temperature is 1505-1525℃, the air volume is 6200-6500m³ / min, start the furnace heat closed-loop control system, and enter the automatic pulverized coal injection control mode.

[0014] (2) Triple protection logic execution: 1) Single adjustment constraint: The control module calculates the theoretically recommended coal injection quantity (M1) every 10 minutes and compares it with the actual coal injection quantity (M0). If the difference exceeds 0.6t / h, it automatically adjusts according to "M=M0±0.6t / h"; 2) Upper and lower limit control: Set the upper and lower limits of coal quantity [25,80]. If M1<25t / h, force output the 25t / h coal injection command; if M1>80t / h, force output the 80t / h coal injection command and trigger the early warning; 3) Fuel ratio linkage: Collect the current coke ratio (CR) and calculate the target coal injection quantity according to "control coal ratio=500-515kg / t.Fe-CR" to ensure that the fuel ratio is within the set range; (3) Command output and verification: The system outputs the final adjustment command to the execution module and monitors the pulverized coal injection rate and fuel ratio data in real time. The verification results show that the fluctuation range of the pulverized coal injection rate is stable within ±0.6t / h, the fuel ratio meets the process requirements, there are no coal shutdowns or exceeding the upper limit, the preset target is fully achieved, and the stable operation of the blast furnace is effectively guaranteed. Example 2

[0015] Taking Taiyuan Iron & Steel Group's No. 6 blast furnace as the implementation object, the blast furnace pulverized coal injection control method of the present invention is applied. The specific steps are as follows: (1) Preliminary preparation: Select the stable operation period of the blast furnace. During this period, the silicon content of molten iron is 0.65-0.75%, the temperature is 1533-1543℃, the air volume is 6200-6500m³ / min, start the furnace heat closed-loop control system, and enter the automatic pulverized coal injection control mode.

[0016] (2) Triple protection logic execution: 1) Fuel ratio linkage: The initial recommended fuel ratio of the automatic pulverized coal injection system is 490 kg / tFe, and the fuel ratio range is limited to [495, 525]. Since it is lower than the lower limit, the fuel ratio is set according to the lower limit of 495 kg / tFe to calculate the pulverized coal injection amount; 2) Single adjustment constraint: The control module calculates the theoretical recommended pulverized coal injection amount (M1) every 10 minutes and compares it with the actual pulverized coal injection amount (M0). If the difference exceeds 0.6 t / h, it will automatically adjust according to "M = M0 ± 0.6 t / h". When the recommended coal amount in the previous 10 minutes is 68.1 and the current recommended coal amount is 67 t / h, the coal amount is limited according to 68.1 ± 0.6 t / h, so the pulverized coal injection amount is 67.5 t / h; 3) Upper and lower limit control: The upper and lower limits of the coal amount are set to [25, 80]. 67.5 t / h is within the limit range, so the final pulverized coal injection amount is 67.5 t / h.

[0017] (3) Command output and verification: The system will output the final adjustment command to the execution module and monitor the coal injection quantity and fuel ratio data in real time.

[0018] 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 method for stable and safe control of an automatic pulverized coal injection system in a blast furnace, characterized in that: Including the following aspects: (1) First layer of protection: Maximum coal addition / reduction limit in a single operation: 1) The control module calculates the "theoretical recommended coal injection amount" M1 every 10 minutes and compares it with the current actual coal injection amount M0; sets the maximum coal addition / reduction amount △m in a single operation, with a value range of 0.3-1.5; 2) If |M1-M0|>△m, the execution module automatically adjusts the coal injection amount according to "M=M0±△m", taking "+" for coal addition and "-" for coal reduction; 3) Users can modify the upper limit of the single adjustment range △m through the "Parameter Setting → Furnace Thermal Closed-Loop Parameter Setting" interface of the monitoring module to adapt to different furnace conditions; (2) Second layer of protection: upper and lower limit locking of coal injection quantity: 1) When the lower limit is triggered: if "theoretical recommended coal injection quantity" < lower limit coal quantity setting value m 下限 The control module forces the use of m 下限 1) Coal injection command to prevent the primary control system from shutting down coal production due to excessively low coal quantity settings; 2) When the upper limit is triggered: if "theoretical recommended coal injection quantity" > upper limit coal quantity setting value m 上限 The control module forces the use of m 上限 Upon receiving the pulverized coal injection command, the monitoring module displays the message "Pulverized coal injection quantity exceeds the upper limit; fuel ratio needs to be checked" on the "Furnace Condition Diagnosis → Pulverized Coal Injection Early Warning Analysis" interface. (3) Third layer of protection: Fuel ratio and coal injection quantity linkage constraint: 1) Based on "fuel ratio = coke ratio + coal ratio", collect and control coke ratio CR, and calculate the target coal injection quantity through "control coal ratio = fuel ratio - CR"; 2) When the system recommends fuel ratio < the manually set lower limit fuel ratio, the system recommends fuel ratio control at 480-580 kg / tFe, and controls coal quantity according to the lower limit fuel ratio to ensure that the coal injection quantity is not lower than the lower limit fuel ratio relative to coal quantity; 3) When the system recommends fuel ratio > the manually set upper limit fuel ratio, controls coal quantity according to the upper limit fuel ratio to ensure that the coal injection quantity is not higher than the upper limit fuel ratio relative to coal quantity.

2. The method for stable and safe control of an automatic pulverized coal injection system in a blast furnace according to claim 1, characterized in that: The second layer of protection includes a lower limit coal quantity setting value m. 下限 The capacity is 12-23 t / h, with the upper limit coal limit set at m. 上限 The capacity is 75-95 t / h.