Automatic blast furnace fan wind reducing system based on multi-condition interlocking triggering

Abstract

This invention relates to the field of iron and steel metallurgy technology, specifically an automatic blast furnace blower reduction system based on multi-condition interlocking triggering. The system includes the following conditions: blast volume condition: current blast volume > blast volume interlocking setpoint; top pressure difference condition: TP1 - TP > top pressure difference interlocking setpoint; blast volume change condition: original blast volume - current blast volume > blast volume change interlocking setpoint. When all three conditions—blast volume, top pressure difference, and blast volume change—are simultaneously met, and the blast furnace and blower sides are under interlocked automatic control, an alarm and a blast reduction command are triggered. Each blast reduction command is locked for one minute, during which time the blast reduction signal is not repeatedly sent to prevent continuous blast reduction in a short period from causing the blower to deviate from its characteristic curve and trigger surge. This invention solves the problems of cumbersome and slow-responding manual blast reduction procedures in existing blast furnaces, achieving automatic and rapid blast reduction when the furnace top pressure is abnormal, and avoiding abnormal large-scale venting.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and particularly to the safety control and fan regulation technology of gas systems in blast furnace ironmaking production. It is especially applicable to the technical field of automatically regulating the fan volume to avoid abnormal large-scale venting under abnormal working conditions of abnormal furnace top pressure in large urban blast furnaces. Background Technology

[0002] In the blast furnace ironmaking process, the furnace top pressure is a core parameter to ensure the safety of the gas system and the stability of production. When the blast furnace top pressure reaches the design threshold, the large venting device will automatically open to prevent the gas system from being damaged by overpressure. However, after it is opened, it will directly discharge gas and soot into the air, which not only wastes energy, but may also cause safety accidents (such as gas leaks), environmental violations (such as particulate matter emissions exceeding limits), and social risks.

[0003] In existing technology, the blast reduction operation when the blast furnace top pressure rises abnormally relies on a manual process. The specific steps are: 1) The blast furnace central control determines that blast reduction is needed; 2) The target blast volume is manually input; 3) The blast furnace side sends a blast reduction signal; 4) The energy department's blower central control receives the signal; 5) The blower room manually inputs the blast volume; 6) The program implements the blower blast reduction. This process has 6 steps, is cumbersome, and is highly dependent on the operator's response speed. It is easy for the blast reduction to be delayed, leading to a continuous increase in furnace top pressure and triggering the large venting anomaly.

[0004] Especially for urban steel plants (such as Taiyuan Iron & Steel), the population density around the plant area is high, and the environmental protection and safety management standards are more stringent: On August 7, 2022, a blast furnace of Taiyuan Iron & Steel was forced to shut down for 3 hours because the pipeline was unable to shut down after the large-scale venting was started. During this period, an additional 300 tons of coke were consumed, directly increasing the cost by 390,000 yuan. At the same time, it faced environmental compliance and public opinion pressure.

[0005] Furthermore, existing air reduction schemes do not incorporate the characteristic curves of large electric fans: blindly and rapidly reducing airflow can easily lead to a mismatch between fan airflow and pressure, deviating from the safe operating curve and causing fan surge; if the air reduction is too small, it cannot quickly reduce the furnace top pressure, still posing a risk of large-scale venting. In summary, existing technologies urgently need an automated control scheme that can achieve "rapid air reduction + equipment safety + environmental compliance". Summary of the Invention

[0006] The technical problem to be solved by this invention is: how to solve the problem of cumbersome and slow response of the existing manual blast furnace blast reduction process, and how to achieve automatic and rapid blast reduction when the furnace top pressure is abnormal, so as to avoid abnormal activation of large-scale venting.

[0007] The technical solution adopted in this invention is: an automatic blast furnace blower reduction system based on multi-condition interlocking triggering.

[0008] Air volume condition: Current air volume > air volume interlock setting value. The air volume interlock setting value is an empirical value based on the blast furnace condition and the historical air volume of the supporting blower.

[0009] Top pressure differential condition: TP1-TP>top pressure differential interlock setting pressure, where TP1 is the real-time measured value of the furnace top pressure, TP is the design setting value of the furnace top pressure, and the top pressure differential interlock setting pressure is an empirical value based on the blast furnace condition;

[0010] Air volume change conditions: Original air volume - Current air volume > Air volume change interlocking setting value. Wherein, the original air volume is the average air volume of the set time before the current time, the air volume change interlocking setting value is an empirical value based on the blast furnace condition, and the setting time is an empirical value based on the blast furnace condition.

[0011] When the conditions for air volume, top pressure difference, and air volume change are met simultaneously, and the blast furnace side and the blower side are under interlocked automatic control, an alarm and air reduction command are triggered. After each air reduction command is triggered, the system is locked for 1 minute, during which time the air reduction signal is not sent repeatedly to prevent the blower from deviating from its characteristic curve and causing surge due to continuous air reduction in a short period of time.

[0012] The interlocking conditions are as follows: the air volume interlocking setting range is 4500~5600m³ / min, the top pressure difference interlocking setting range is 7~13kPa, the air volume change difference interlocking setting range is 250~290m³ / min, and the average air volume statistical setting time is 10s~15s.

[0013] Each time a blast reduction command is triggered, the control unit generates a "blast reduction set rate" command and sends it to the blower-side execution unit. The blower-side execution unit controls the variable frequency blower to reduce the air volume from the current value to the set rate within the set execution time. The air volume sensor provides real-time feedback on the adjusted air volume of the variable frequency blower to the control unit. After the control unit confirms that the air volume meets the standard, the current blast reduction cycle ends. The set rate is an empirical value based on the blast furnace conditions and is a fixed value.

[0014] The control unit generates "wind reduction of 200-400m" 3 The command is " / min".

[0015] The beneficial effects of this invention are: 1. It solves the problems of cumbersome and slow response in the existing manual blast furnace blast reduction process, realizing automatic and rapid blast reduction when the furnace top pressure is abnormal, and avoiding abnormal start-up of large venting; 2. It combines the characteristic curve of large electric fans to design blast reduction parameters, preventing fans from surging due to blast reduction, and sets a lower limit for safe blast volume in the blast furnace to avoid blast interruption accidents caused by continuous blast reduction; 3. It eliminates safety accidents (such as gas leaks), environmental violations, and social risks caused by abnormal start-up of large venting, and is compatible with the stringent control requirements of urban steel plants; 4. It reduces blast furnace shutdowns caused by the inability to shut down after large venting is started, reduces production costs such as coke consumption, and creates stable economic benefits. Detailed Implementation

[0016] This invention utilizes a closed-loop control logic of "detection-judgment-execution-feedback" and designs core parameters based on equipment characteristics to achieve automatic fan reduction and prevention of abnormal large-scale venting. The specific solution is as follows:

[0017] System Composition

[0018] This invention relies on the collaborative operation of the following hardware and software modules, the functions of which are as follows: .

[0019] Core control logic

[0020] The automatic wind reduction triggering of this invention requires the simultaneous fulfillment of the following four logical conditions, and sets one safety restriction, as follows:

[0021] Basic conditions: Interlocking system implementation

[0022] The interlock function between the blast furnace side and the blower side must be in the "engaged" state (displayed in green on the HMI screen), at which time the program has the authority to send commands; if the interlock is not engaged (displayed in red), the program will not trigger automatic blast reduction, and only manual operation authority will be retained.

[0023] Air volume condition: Current air volume > 5500 m³ / min. Set 5500 m³ / min as the lower limit interlock value for safe air volume of blast furnace: If the current air volume ≤ 5500 m³ / min, even if other conditions are met, the program will not trigger air reduction, to avoid continuous air reduction leading to blast furnace interruption and to ensure stable reaction inside the furnace.

[0024] Top pressure difference condition: TP1-TP>10Kpa. Wherein, TP1 is the real-time measured value of the furnace top pressure, and TP is the design set value of the furnace top pressure; when the top pressure difference exceeds 10Kpa, it is judged as "abnormal increase in top pressure", and the air reduction needs to be activated.

[0025] Air volume change conditions: Original air volume - Current air volume > 290 m³ / min. By comparing the historical air volume (original air volume, taking the average air volume of the previous 10 seconds) with the current air volume (current air volume), it is ensured that the air volume decrease trend conforms to the "reduction of air volume" condition, and the reduction of air volume is not erroneously triggered due to instantaneous fluctuations of the sensor.

[0026] Safety Restriction: No continuous air reduction signals will be sent within 1 minute. After each air reduction command is triggered, the program will be locked for 1 minute, during which time air reduction signals will not be sent repeatedly to prevent the fan from deviating from its characteristic curve and causing surge due to continuous air reduction in a short period of time.

[0027] The wind reduction parameters were designed based on the characteristic curves of the large electric fans from the Energy Department of Taiyuan Iron & Steel Group. The core wind reduction parameters were then designed as follows:

[0028] Single air reduction range: 300 m³ / min. Simulation of the fan characteristic curve has verified that a reduction of 300 m³ / min can rapidly reduce the furnace top pressure within 10-15 seconds (reduction ≥ 8 kPa), while simultaneously preventing imbalance between air volume and air pressure, ensuring the fan always operates within the safe curve range (away from the surge zone).

[0029] The airflow reduction command execution process involves the control unit determining that all triggering conditions are met and generating a "reduce airflow by 300 m³ / min" command. The command is transmitted to the fan-side execution unit via industrial Ethernet. The fan frequency converter receives the command and reduces the airflow from the current value to the target value (e.g., reduce the current airflow of 6000 m³ / min to 5700 m³ / min) within 10 seconds.

[0030] The air volume sensor provides real-time feedback on the adjusted air volume. Once the control unit confirms that the air volume meets the standard, the current air reduction cycle ends.

[0031] Status monitoring and alarm design

[0032] Interlock status monitoring: HMI screen 1 ("Top pressure differential alarm / active fan wind reduction interlock in action") displays the interlock status in real time: green = interlock in action, red = interlock not in action; it also displays the current TP1, TP and top pressure differential values.

[0033] When an abnormal alarm is triggered, and the conditions of "interlock activation + top pressure difference > 10 kPa" are met, the alarm indicator in the HMI screen ("top pressure difference greater than 10 kPa") will flash red, and the audible and visual alarm will be activated (continuous alarm until top pressure difference ≤ 8 kPa) to remind the operator to pay attention to the operating conditions and intervene in manual control if necessary.

[0034] In one embodiment, the application targets, the No. 5 and No. 6 blast furnaces of Taiyuan Iron & Steel Plant, are both large-scale urban blast furnaces with residential areas within 3km of them, and the environmental protection and safety management requirements are stringent.

[0035] Airflow fluctuation condition on October 29, 2024

[0036] The working condition was triggered at 23:45. Due to changes in the permeability inside the furnace, the gas flow in the No. 5 blast furnace was unstable. TP1 rapidly increased from 250Kpa (TP set value) to 262Kpa, and the top pressure difference (TP1-TP) reached 12Kpa. At this time, the current air volume of the blower was 6200m³ / min, the original air volume (average of the previous 10 seconds) was 6500m³ / min, the air volume difference was 300m³ / min, and the interlock was in the "engaged" state (meeting all triggering conditions).

[0037] Execution: The control unit generates a "reduce airflow by 300 m³ / min" command within 0.3 seconds and transmits it to the fan side via industrial Ethernet; after receiving the command, the fan frequency converter reduces the airflow from 6200 m³ / min to 5900 m³ / min within 8 seconds.

[0038] Operating results: 15 seconds after the wind was reduced, TP1 dropped to 253 kPa, the top pressure difference was 3 kPa, and the large venting was not triggered; the alarm indicator on the HMI screen stopped flashing, the audible and visual alarms were turned off, and the operating conditions returned to stability, avoiding one environmental incident and potential wind shutdown risk.

[0039] The benefits of this invention are reflected in three dimensions: economy, environmental protection, and safety. The data comes from the actual application verification in the blast furnace of Taiyuan Iron & Steel Group (implemented since November 2023):

[0040] Economic benefits: The basis for cost savings calculation is as follows: Before implementation (August 7, 2022), due to the pipeline route, the large vent could not be shut down after it was opened, the blast furnace was shut down for 3 hours, and an additional 300 tons of coke was consumed (the coke combustion efficiency decreases when the blast furnace is shut down, and fuel needs to be added to maintain the furnace temperature), with a coke unit price of 1300 yuan / ton.

[0041] Cost calculation for a single shutdown: Additional cost for a single shutdown = Coke consumption × Coke unit price = 300t × 1300 yuan / t = 390,000 yuan.

[0042] Long-term benefit forecast: After the implementation of the program, no abnormal opening or shutdown of large-scale venting due to untimely wind reduction has occurred. Calculated based on avoiding one shutdown per year, the projected economic benefits for the next five years (2024-2028) are: RMB 390,000 / year × 5 years = RMB 1,950,000.

[0043] Environmental benefits: It eliminates the direct discharge of gas and dust caused by abnormal opening of large-scale venting, reducing pollutant emissions by about 0.3t each time; it complies with the requirement of "Emission Standard of Air Pollutants for Iron and Steel Industry" (GB28664-2012) that "blast furnace gas venting should be collected and treated and should not be directly discharged", avoiding the risk of environmental penalties (the penalty for a single environmental violation is ≥200,000 yuan).

[0044] Safety benefits: This invention avoids safety accidents such as explosions and poisoning caused by direct gas discharge, reducing safety risks for operators; it also reduces production interruptions caused by abnormal large-scale venting, ensuring continuous and stable operation of the blast furnace. This invention is a pioneering technology developed by the company and has been successfully applied in Taiyuan Iron & Steel Group's No. 5 and No. 6 blast furnaces, adapting to the operating conditions of large urban blast furnaces.

Claims

1. An automatic blast furnace blower blast reduction system based on multi-condition interlocking triggering, characterized in that: Air volume condition: Current air volume > air volume interlock setting value. The air volume interlock setting value is an empirical value based on the blast furnace condition and the historical air volume of the supporting blower. Top pressure differential condition: TP1-TP>top pressure differential interlock setting pressure, where TP1 is the real-time measured value of the furnace top pressure, TP is the design setting value of the furnace top pressure, and the top pressure differential interlock setting pressure is an empirical value based on the blast furnace condition; Air volume change conditions: Original air volume - Current air volume > Air volume change interlocking setting value. Wherein, the original air volume is the average air volume of the set time before the current time, the air volume change interlocking setting value is an empirical value based on the blast furnace condition, and the setting time is an empirical value based on the blast furnace condition. When the air volume condition, top pressure difference condition, and air volume change interlock condition are met simultaneously, and the blast furnace side and the blower side are under interlocked automatic control, an alarm and air reduction command are triggered. After each air reduction command is triggered, the system is locked for 1 minute, during which time the air reduction signal is not sent repeatedly to prevent the blower from deviating from its characteristic curve and causing surge due to continuous air reduction in a short period of time.

2. The automatic blast furnace blower reduction system based on multi-condition interlocking triggering according to claim 1, characterized in that: The air volume interlock setting range is 4500~5600m³ / min, the top pressure difference interlock setting range is 7~13kPa, the air volume change difference interlock setting range is 250~290m³ / min, and the average air volume statistical setting time is 10s~15s.

3. The automatic blast furnace blower reduction system based on multi-condition interlocking triggering according to claim 1, characterized in that: Each time a blast reduction command is triggered, the control unit generates a "blast reduction set rate" command and sends it to the blower-side execution unit. The blower-side execution unit controls the variable frequency blower to reduce the air volume from the current value to the set rate within the set execution time. The air volume sensor provides real-time feedback on the adjusted air volume of the variable frequency blower to the control unit. After the control unit confirms that the air volume meets the standard, the current blast reduction cycle ends. The set rate is an empirical value based on the blast furnace conditions and is a fixed value.

4. The automatic blast furnace blower reduction system based on multi-condition interlocking triggering according to claim 3, characterized in that: The control unit generates "wind reduction of 200-400m" 3 The command is " / min".