Method for preventing and controlling fluctuation of gas heating furnace replacement and stable operation of the same

Abstract

The present application belongs to the technical field of operation control of blast furnace supporting gas heating furnace, and specifically discloses a method for preventing and controlling fluctuation of gas heating furnace replacement and stable operation. Through system analysis of replacement fluctuation causes, nitrogen pressure equalization multi-furnace collaborative control technology, grouping and combination standardization replacement process, multi-dimensional fluctuation early warning and emergency disposal, and whole cycle stable operation guarantee, five core links, precise closed loop control of pressure in the replacement process is realized. The system air pressure fluctuation can be controlled within ±0.02MPa, the replacement time is shortened to 25-32 minutes, the blast furnace permeability index fluctuation is ≤±0.3, the molten iron temperature fluctuation is ≤±10℃, the thermal efficiency is improved by 8-10%, the gas consumption is reduced by 12-15%, and the safety accident rate is 0. The method has high standardization degree and strong adaptability, and can be widely applied to similar multi-furnace supporting blast furnace smelting systems.

Description

Technical Field

[0001] This invention relates to the field of operation control technology for blast furnace-supporting gas heaters, and in particular to a method for preventing and controlling fluctuations in gas heater operation and ensuring stable operation. Background Technology

[0002] Gas heating furnace as 2500m 3 The core supporting equipment of the HyCROF blast furnace smelting system undertakes the key functions of gas preheating and heat energy recovery and utilization. Its operational stability directly determines the blast furnace blast temperature, gas utilization rate, and overall smelting efficiency. 2500m 3 The alternating operation of multiple furnaces in a HyCROF blast furnace with three gas-fired heaters is a necessary step to meet the continuous heat demand of blast furnace production. However, existing furnace switching technologies have several prominent bottlenecks: First, the pressure imbalance during multi-furnace switching is a significant problem. Traditional furnace switching lacks a targeted pressure balancing mechanism, and the system air pressure fluctuation range reaches ±0.05-0.1 MPa when the three furnaces are switched alternately, causing safety risks such as unstable gas combustion, flameout, and even backfire. This pressure fluctuation is even more severe when switching between furnaces #1 and #3 due to differences in pipeline distance. Second, the furnace condition has a significant cascading effect. Air pressure fluctuations are transmitted to the blast furnace through the pipeline system, causing the furnace permeability index to fluctuate by ±0.5-1.0. The problems include: 1) Disrupting the stability of the charge column, inducing abnormal conditions such as charge suspension and collapse, causing molten iron temperature fluctuations of ±30-50℃, severely affecting the consistency of molten iron quality; 2) Lack of standardization in the multi-furnace switching process, with no differentiated operating procedures developed for different combinations of switching between the three furnaces (1#↔2#, 2#↔3#, 1#↔3#), relying on operator experience and judgment, resulting in long switching times (≥30 minutes), and the possibility of exacerbating fluctuations due to errors in the operating sequence; 3) Immature pressure control technology, with traditional furnace switching using natural pressure relief or forced exhaust methods, failing to achieve precise closed-loop pressure control during multi-furnace switching, leading to sudden changes in furnace heat load, a 10-15% decrease in thermal efficiency, and increased gas consumption and pollutant emissions. These problems severely restrict the operation of the three gas-fired furnaces and the 2500m³... 3 The coordinated and stable operation of the HyCROF blast furnace system urgently requires the establishment of a complete technical system covering "multi-furnace pressure balance control - differentiated furnace changeover process - fluctuation early warning and emergency response - stable operation guarantee" to solve the problem of fluctuations during multi-furnace changeover. Summary of the Invention

[0003] The purpose of this invention is to provide a method for controlling and stabilizing the operation of a gas-fired boiler during furnace changeover, specifically for a 2500m³ boiler. 3The HyCROF blast furnace is equipped with three gas-fired heating furnaces. By constructing a nitrogen pressure equalization multi-furnace coordinated control technology, formulating differentiated and standardized furnace replacement procedures, and establishing a fluctuation early warning and emergency response mechanism, the problems of large air pressure fluctuations, serious impact on furnace conditions, and non-standard operation during the existing multi-furnace furnace replacement process are solved, so as to achieve a smooth and efficient furnace replacement process and stable system operation.

[0004] To achieve the above objectives, the basic solution provided by this invention is: a method for controlling and stabilizing the operation of a gas-fired heating furnace during furnace changeover, comprising the following steps: S1: For 2500m 3 The HyCROF blast furnace was equipped with three gas-fired heating furnaces (No. 1, No. 2, and No. 3) for furnace changeover fluctuation analysis, and a multi-furnace coordinated control system for nitrogen pressure equalization was designed. S2: Develop standardized furnace replacement procedures for different furnace types, including pre-replacement preparation, furnace type switching operations, and post-replacement stability assurance. S3: Establish a multi-dimensional early warning system for furnace changeover fluctuations and an emergency response mechanism for typical operating conditions; S4: Build a stable operation guarantee system that includes equipment maintenance, personnel training, and continuous optimization.

[0005] Furthermore, the nitrogen pressure equalization multi-furnace coordinated control system mentioned in step S1 includes: Nitrogen source configuration: Nitrogen source with purity ≥ 99.9%, 10m 3 Main nitrogen tank, 3 x 3m 3 The pressure of the main nitrogen tank is stabilized at 0.6-0.8 MPa, and the pressure of the branch buffer tank is maintained at 0.45-0.5 MPa through a pressure reducing valve, ensuring a stable nitrogen supply and rapid response. Pressure equalization pipeline layout: Pressure equalization branch pipes are installed 5m away from the gas inlet pipes of boilers 1, 2, and 3, and 3m away from the gas exhaust pipes. The diameter of the pressure equalization branch pipes is 50mm, and they are equipped with intelligent flow regulating valves, pressure sensors, check valves, and sub-pressure equalization valves; and a main pressure equalization valve is installed on the main gas pipe to achieve global pressure balance control. Control system integration: Link the intelligent flow regulating valve, pressure sensor, and sub-pressure equalization valve of the pressure equalization branch pipe with the blast furnace central control platform, and develop a multi-furnace pressure collaborative control module, integrating pressure monitoring, flow regulation, and furnace change logic judgment functions, with a response time of ≤1 second, so as to realize automatic matching of pressure equalization parameters for different furnace change combinations.

[0006] Furthermore, the equalization parameters are: During the furnace replacement process, the system air pressure remained stable at 0.43-0.47 MPa, with a fluctuation range of ≤ ±0.02 MPa, and the inter-furnace pressure difference was ≤ 0.01 MPa. The nitrogen flow rate control for the furnace replacement assembly is as follows: 1# #2 Switching: Depressurization nitrogen flow rate 8-10 Nm 3 / h increments, boosting voltage by 12-15Nm 3 / h decreases, stable at 3-5Nm 3 / h; 2# #3 Switching: Depressurization nitrogen flow rate 10-12 Nm 3 / h increments, boosting voltage by 15-18Nm 3 / h decreases, stable at 4-6Nm 3 / h; 1# #3 Switchover: Pre-pressure equalization 15 minutes before furnace switchover, depressurization 12-15 Nm 3 / h increments, boosting voltage by 18-20Nm 3 / h decreases, stable at 5-7Nm 3 / h.

[0007] Furthermore, the furnace replacement combination durations are as follows: 1# The total switching time for boiler #2 was 25 minutes. 2# The total switching time for boiler #3 was 28 minutes. 1# The total switching time for boiler #3 was 32 minutes.

[0008] Furthermore, the opening and closing rate of the gas inlet valve on the gas inlet pipeline during the furnace replacement operation is 10% / min.

[0009] Furthermore, the early warning system described in step S3 is configured with two levels of early warning: Level 1 warning: Wind pressure fluctuation ±0.02MPa, flow rate fluctuation ±15%, CO > 500ppm, air permeability index > 4.5; Level II Warning: Wind pressure fluctuation ±0.03MPa, flow rate fluctuation ±20%, CO > 800ppm, air permeability index > 5.0; If the situation is not resolved within 3 minutes of a Level 2 warning, the system will automatically shut down and switch to the original operating furnace.

[0010] Furthermore, the emergency response described in step S3 includes: Sudden drop in wind pressure: Increase nitrogen flow rate by 5-10 Nm 3 / h, the valve opening and closing rate drops to 5% / min; Sudden increase in air pressure: Reduce nitrogen flow rate, open pressure relief valve, and control pressure to not exceed 0.5 MPa; Unstable combustion: Adjust the air-fuel ratio by 10-15%. If the flame goes out, purge with nitrogen for ≥5 minutes and then reignite. Blast furnace condition fluctuations: Suspend furnace replacement, reduce blast furnace blast by 5-10%, and resume furnace replacement after stabilization.

[0011] Furthermore, the equipment maintenance described in step S4 includes: Daily checks of nitrogen pressure and pipe seals; weekly sensor calibration; quarterly valve disassembly and cleaning; annual cleaning of the furnace and heat exchangers.

[0012] Furthermore, the personnel training mentioned in step S4 includes theoretical training, simulated practice, and case review. Only those who pass the assessment can be assigned to their posts, and the emergency response time is ≤3 minutes.

[0013] Furthermore, the furnace replacement process must avoid the periods of blast furnace blasting adjustment and tapping; nitrogen dew point ≤ -40℃, system pressure holding 0.5MPa, and pressure drop ≤ 0.005MPa after 30 minutes are considered qualified.

[0014] Compared with the prior art, the advantages of this invention are: By adopting nitrogen pressure equalization and multi-furnace coordinated control technology, the system wind pressure fluctuation of three furnaces with different combinations of furnace switching is controlled within ±0.02MPa, which is 70-80% lower than traditional furnace switching; the pressure difference between each furnace is ≤0.01MPa, which completely solves the problem of pressure gradient imbalance during multi-furnace switching; the furnace switching time is shortened to 25-32 minutes, which is 30-40% lower than traditional furnace switching.

[0015] During the furnace changeover process, the blast furnace permeability index fluctuates by ≤±0.3 and the molten iron temperature fluctuates by ≤±10℃, which is 60-70% lower than traditional furnace changeover. It effectively avoids abnormal operating conditions such as hanging and collapsing caused by furnace changeover fluctuations, and reduces unplanned blast furnace shutdown time by more than 80%.

[0016] By precisely controlling sudden changes in heat load and combustion status, the thermal efficiency of the gas-fired boiler is increased by 8-10%, and gas consumption is reduced by 12-15%; CO emission concentration is controlled at ≤300ppm, meeting environmental protection requirements; standardized furnace replacement operation reduces human error, equipment failure rate is reduced by 60%, and maintenance costs are reduced by 40%.

[0017] A multi-dimensional early warning system and emergency response mechanism ensure timely detection and rapid handling of abnormal fluctuations, with a response time of ≤3 minutes for Level II early warnings; the nitrogen equalization system effectively prevents safety risks such as gas backfire and leakage, and the accident rate during furnace replacement operations is 0.

[0018] This method develops differentiated solutions for different furnace replacement combinations of three gas-fired boilers, fully adaptable to 2500m³. 3 HyCROF blast furnace meets operational requirements; its operation procedures are standardized, its technical solutions are replicable, and it can be widely applied to similar multi-furnace blast furnace systems, thus possessing broad industrial application value. Detailed Implementation

[0019] The present invention will be further described in detail below through specific embodiments: A method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace includes the following steps: S1: For 2500m 3 The HyCROF blast furnace was equipped with three gas-fired heating furnaces (No. 1, No. 2, and No. 3) for furnace changeover fluctuation analysis, and a multi-furnace coordinated control system for nitrogen pressure equalization was designed. The nitrogen pressure equalization multi-furnace coordinated control system includes: Nitrogen source configuration: Nitrogen source with purity ≥ 99.9%, 10m 3 Main nitrogen tank, 3 x 3m 3 The pressure of the main nitrogen tank is stabilized at 0.6-0.8 MPa, and the pressure of the branch buffer tank is maintained at 0.45-0.5 MPa through a pressure reducing valve, ensuring a stable nitrogen supply and rapid response. Pressure equalization pipeline layout: Pressure equalization branch pipes are installed 5m away from the gas inlet pipes of boilers #1, #2, and #3, and 3m away from the gas exhaust pipes. The diameter of the pressure equalization branch pipes is 50mm, and they are equipped with intelligent flow regulating valves, pressure sensors, check valves, and sub-pressure equalization valves. A main pressure equalization valve is installed on the main gas pipe to achieve global pressure balance control. A gas inlet valve is installed on the gas inlet pipe. Control system integration: Link the intelligent flow regulating valve, pressure sensor, and sub-pressure equalization valve of the pressure equalization branch pipe with the blast furnace central control platform, and develop a multi-furnace pressure collaborative control module, integrating pressure monitoring, flow regulation, and furnace change logic judgment functions, with a response time of ≤1 second, so as to realize automatic matching of pressure equalization parameters for different furnace change combinations.

[0020] The pressure equalization parameters are as follows: during the furnace replacement process, the system air pressure is stable at 0.43-0.47MPa, the fluctuation range is ≤±0.02MPa, and the pressure difference between furnaces is ≤0.01MPa; The nitrogen flow rate control for the furnace replacement assembly is as follows: 1# #2 Switching: Depressurization nitrogen flow rate 8-10 Nm 3 / h increments, boosting voltage by 12-15Nm 3 / h decreases, stable at 3-5Nm 3 / h; 2# #3 Switching: Depressurization nitrogen flow rate 10-12 Nm 3 / h increments, boosting voltage by 15-18Nm 3 / h decreases, stable at 4-6Nm 3 / h; 1# #3 Switchover: Pre-pressure equalization 15 minutes before furnace switchover, depressurization 12-15 Nm 3 / h increments, boosting voltage by 18-20Nm 3 / h decreases, stable at 5-7Nm 3 / h; Furnace changing combination durations are as follows: 1# The total switching time for boiler #2 was 25 minutes. 2# The total switching time for boiler #3 was 28 minutes. 1# The total switching time for boiler #3 was 32 minutes.

[0021] S2: Develop a standardized furnace replacement process for different furnace types, including pre-replacement preparation, furnace type switching operation, and post-replacement stability assurance; the opening and closing rate of the gas inlet valve on the gas inlet pipeline during the furnace replacement operation is 10% / min.

[0022] S3: Establish a multi-dimensional early warning system for furnace changeover fluctuations and an emergency response mechanism for typical operating conditions; the early warning system is set up with two levels of early warning: Level 1 warning: Wind pressure fluctuation ±0.02MPa, flow rate fluctuation ±15%, CO > 500ppm, air permeability index > 4.5; Level II Warning: Wind pressure fluctuation ±0.03MPa, flow rate fluctuation ±20%, CO > 800ppm, air permeability index > 5.0; If the situation is not resolved within 3 minutes of a Level 2 warning, the system will automatically shut down and switch to the original operating furnace.

[0023] Emergency response includes: Sudden drop in wind pressure: Increase nitrogen flow rate by 5-10 Nm 3 / h, the valve opening and closing rate drops to 5% / min; Sudden increase in air pressure: Reduce nitrogen flow rate, open pressure relief valve, and control pressure to not exceed 0.5 MPa; Unstable combustion: Adjust the air-fuel ratio by 10-15%. If the flame goes out, purge with nitrogen for ≥5 minutes and then reignite. Blast furnace condition fluctuations: Suspend furnace replacement, reduce blast furnace blast by 5-10%, and resume furnace replacement after stabilization.

[0024] S4: Establish a stable operation guarantee system for equipment maintenance, personnel training, and continuous optimization; equipment maintenance includes: daily checks of nitrogen pressure and pipeline seals; weekly sensor calibration; quarterly valve disassembly and cleaning; and annual cleaning of the furnace and heat exchanger. Personnel training includes theoretical training, simulated operation, and case review. Only those who pass the assessment can be assigned to their posts. Emergency response time must be ≤3 minutes. The furnace changeover process must be avoided during the blast furnace blasting and tapping periods. The nitrogen dew point must be ≤-40℃, and the system pressure must be maintained at 0.5MPa with a pressure drop of ≤0.005MPa over 30 minutes to be considered qualified.

[0025] The following are examples of the application of the above method in actual blast furnace smelting: I. Experiment Preparation and System Setup 1. Test subject: 2500m 3 The HyCROF blast furnace is equipped with No. 1, No. 2 and No. 3 gas heating furnaces, with rated heat loads of 30MW, 30MW and 40MW respectively, and a gas main pressure of 0.45MPa. Under normal operation, the furnaces adopt the mode of "two furnaces in operation and one furnace on standby", and the furnace replacement frequency is twice a day (once in the morning shift and once in the evening shift).

[0026] 2. System upgrade and setup: Nitrogen equalization system: Install main nitrogen tank (10m³) 3 ), 3 branch buffer tanks (each with a volume of 3m³) 3 A nitrogen drying device (dew point ≤ -40℃) is configured; pressure equalization branch pipes (50mm diameter) are installed in the gas inlet and exhaust pipes of each boiler; and intelligent flow regulating valves (model: ZAZP-50, adjustment accuracy ±1Nm) are installed on the pressure equalization branch pipes. 3 / h), pressure sensor (model: PT208, accuracy ±0.005MPa), check valve and pressure equalization valve; a main pressure equalization valve (model: ZAZN-80) is installed on the main gas pipe.

[0027] Monitoring system: Added 8 pressure monitoring points and 6 flow monitoring points, upgraded the combustion flame detector to infrared imaging type (model: IR-FLAME-200); linked all monitoring equipment with the central control platform (S7-1500PLC+WinCC monitoring software), and developed a multi-furnace pressure collaborative control module.

[0028] Training and Assessment: We compiled the "Operation Manual for Replacing Three Gas Heating Furnaces" and organized two months of theoretical and practical training for operators. After the training, we conducted an assessment, and all operators passed the assessment (average theoretical score of 88 points and average practical score of 92 points).

[0029] II. Implementation and Effect Verification of Furnace Replacement by Combination 1, 1# Switchover of Boiler #2 to be carried out (morning shift, January 10, 2026) Preparations before furnace changeover (T-10 minutes): Equipment inspection: Burners of furnaces #1 and #2 were not blocked; the pressure of the main nitrogen tank was 0.7 MPa; the pressure of the branch buffer tank was 0.48 MPa; the air tightness of the pressure equalization pipeline was qualified; the blast furnace operating conditions were stable (pressure difference 160 kPa, permeability index 4.2, molten iron temperature 1495℃).

[0030] Parameter preset: Central control system selected "1#" "Boiler #2 switching" mode, automatically loading equalization parameters (nitrogen flow rate 8-10 Nm during pressure relief phase). 3 / h, boost phase 12-15Nm 3 / h).

[0031] Furnace replacement operation implementation: T0-T10 minutes (pressure relief and equalization): At minute T0: The central control system issues a furnace change command. The gas inlet valve of boiler #1 begins to close at a rate of 10% / min, and simultaneously opens the pressure equalization valve on the pressure equalization branch pipe connected to the gas inlet pipeline of boiler #1. The nitrogen flow rate gradually increases from 0 to 10 Nm³. 3 / h; Boiler #2 maintains the combustion system in a preheated state, and the gas inlet valve is in the closed state; T5 minutes: The gas inlet valve of boiler #1 is closed 50% of the way, and the nitrogen flow rate is maintained at 10 Nm. 3 / h; Monitoring showed that the pressure of boiler #1 dropped from 0.45MPa to 0.42MPa, with a fluctuation range of -0.03MPa. Flow compensation was initiated, increasing the nitrogen flow rate to 12Nm. 3 / h; T10 minutes: The gas inlet valve of No. 1 boiler is completely closed, and the pressure is stable at 0.43MPa; the pressure equalization valve on the pressure equalization branch pipe connected to the gas inlet pipeline of No. 1 boiler is closed, and preparation is made to switch to the pressure equalization stage.

[0032] T10-T20 minutes (pressure rise and equalization phase): T10 minutes: The gas inlet valve of boiler #2 begins to open at a rate of 10% / min, and the pressure equalization valve on the pressure equalization branch pipe connected to the gas inlet pipeline of boiler #2 opens simultaneously, increasing the nitrogen flow rate from 15 Nm³ / min. 3 / h gradually decreases; T15 minutes: The gas inlet valve of boiler #2 opens 50%, and the pressure rises to 0.44 MPa; the nitrogen flow rate drops to 8 Nm³. 3 / h, monitor the pressure difference between boiler #2 and the main gas pipe ≤0.01MPa; T20 minutes: The gas inlet valve of No. 2 boiler is fully opened and the pressure is stabilized at 0.45MPa; the pressure equalization valve on the pressure equalization branch pipe connected to the gas inlet pipeline of No. 2 boiler is closed, and the system switches to the stable stage.

[0033] T20-T25 minutes (stabilization phase): Continuously monitor the flue gas temperature of furnace #1 as it gradually decreases to 300℃, the flame of furnace #2 stabilizes, the CO emission concentration is 280ppm, the system air pressure is 0.45±0.01MPa; the blast furnace permeability index is 4.3, the molten iron temperature is 1492℃, and the fluctuation range is -3℃; after confirming that there is no fluctuation, the furnace changeover operation is completed.

[0034] Implementation results: The total furnace replacement time was 25 minutes, the maximum fluctuation range of air pressure was ±0.015MPa, the fluctuation range of gas flow was ±12%, and there was no significant fluctuation in the blast furnace condition, achieving the expected results.

[0035] 2, 2# Switchover of Boiler #3 (Evening shift, January 11, 2026) Preparations before furnace changeover (T-12 minutes): Equipment inspection: No blockage in the flue gas duct of furnace #2; preheated burner of furnace #3 to 850℃; main nitrogen tank pressure 0.68MPa; branch buffer tank pressure 0.47MPa; blast furnace operating conditions stable (pressure difference 155kPa, permeability index 4.1, molten iron temperature 1498℃).

[0036] Parameter preset: Select "2#" "Boiler #3 switching" mode, loading equalization parameters (nitrogen flow rate 10-12 Nm during pressure relief phase) 3 / h, boost phase 15-18Nm 3 / h).

[0037] Furnace replacement operation implementation: T0-T12 minutes (pressure relief and equalization phase): T0 minutes: The gas inlet valve of boiler #2 closes at a rate of 10% / min, and the pressure equalization valve on the pressure equalization branch pipe connected to the gas inlet pipeline of boiler #2 is opened, gradually increasing the nitrogen flow rate from 0 to 12 Nm³. 3 / h; The burner of furnace #3 is kept in a preheated state at 850℃.

[0038] T6 minutes: The gas inlet valve of boiler #2 is closed 50%, the pressure drops to 0.41 MPa, and the nitrogen flow rate increases to 15 Nm³. 3 / h, to compensate for differences in pipeline resistance.

[0039] T12 minutes: The gas inlet valve of No. 2 boiler is completely closed, and the pressure is stable at 0.43MPa; the pressure equalization valve on the pressure equalization branch pipe connected to the gas inlet pipeline of No. 2 boiler is closed.

[0040] T12-T25 minutes (pressure rise and equalization phase): T12 minutes: The gas inlet valve of boiler #3 opens at a rate of 10% / min, and the pressure equalization valve on the pressure equalization branch pipe connected to the gas inlet pipeline of boiler #3 is opened, and the nitrogen flow rate increases from 18 Nm³ / min. 3 / h gradually decreases.

[0041] T18 minutes: The gas inlet valve of boiler #3 is opened to 50%, and the pressure rises to 0.44MPa; due to the high heat load of boiler #3, the burner firepower is adjusted synchronously, gradually increasing from the preheating state to 50% of the rated load.

[0042] T25 minutes: The gas inlet valve of boiler #3 is fully opened and the pressure is stabilized at 0.45MPa; the pressure equalization valve on the pressure equalization branch pipe connected to the gas inlet pipeline of boiler #3 is closed.

[0043] T25-T28 minutes (stabilization phase): Continuously monitor the flue gas temperature of furnace #3. When it reaches 1000℃, it stabilizes, the heat load output reaches 100%, the system air pressure is 0.45±0.01MPa, the CO emission concentration is 290ppm, the blast furnace permeability index is 4.2, the molten iron temperature is 1495℃, and the fluctuation range is -3℃. After confirming that the parameters are stable, the furnace change is completed.

[0044] Implementation results: The total furnace switching time was 28 minutes, the maximum fluctuation range of air pressure was ±0.018MPa, the fluctuation range of gas flow was ±14%, the heat load switching of No. 3 furnace was stable, and there were no combustion abnormalities.

[0045] 3, 1# Switchover of Boiler #3 (January 12, 2026, afternoon shift) Preparations before furnace changeover (T-15 minutes): Equipment inspection: The insulation layer of the pipelines of furnaces #1 and #3 is intact; the pressure of the main nitrogen tank is 0.72 MPa; the pressure of the branch buffer tank is 0.49 MPa; the main pressure equalization valve is started 15 minutes in advance to pre-balance the pipeline pressure difference to 0.005 MPa; the blast furnace operating conditions are stable (pressure difference 162 kPa, permeability index 4.3, molten iron temperature 1490℃).

[0046] Parameter preset: Select "1#" "No. 3 Furnace Switching" mode, loading equalization parameters (nitrogen flow rate 10 Nm³ during pre-equalization stage). 3 / h, depressurization phase 12-15Nm 3 / h, boost phase 18-20Nm 3 / h).

[0047] Furnace replacement operation implementation: T0-T15 minutes (pre-pressure equalization + pressure relief equalization): Pre-pressure equalization is completed during T0-T5 minutes, and the pipeline pressure stabilizes at 0.45MPa; T5-T15 minutes: The gas inlet valve of No. 1 boiler is closed, and the pressure equalization branch valve on the pressure equalization branch pipe connected to the gas inlet pipeline of No. 1 boiler is opened, and the nitrogen flow rate is gradually increased to 15Nm. 3 / h; At T15 minutes, the gas inlet valve of boiler #1 was completely closed, and the pressure stabilized at 0.43MPa.

[0048] T15-T28 minutes (Pressure Increase and Equalization): The gas inlet valve of boiler #3 opens, and the pressure equalization valve on the branch pipe connected to the gas inlet pipeline of boiler #3 opens, increasing the nitrogen flow rate from 20 Nm³. 3The pressure is gradually reduced by h; the main equalizing valve is opened simultaneously to assist in pressure increase; at T22 minutes, the gas inlet valve of No. 3 boiler is opened to 50%, and the pressure rises to 0.44MPa; at T28 minutes, the gas inlet valve is fully opened, the pressure stabilizes at 0.45MPa, and the main equalizing valve and the sub-equalizing valve on the equalizing branch pipe connected to the gas inlet pipeline of No. 3 boiler are closed.

[0049] T28-T32 minutes (stable stage): Combustion in furnace #3 is stable, CO emission concentration is 300ppm; blast furnace permeability index is 4.4, molten iron temperature is 1488℃, fluctuation range is -2℃.

[0050] Implementation results: The total furnace replacement time was 32 minutes, the maximum fluctuation range of air pressure was ±0.02MPa, and the fluctuation range of gas flow was ±15%, which reduced the fluctuation range by 73% compared with the traditional furnace replacement method, and the blast furnace condition was stable.

[0051] 4. Emergency Response Drill Implementation (January 15, 2026) Simulation 1# Emergency scenario for sudden pressure drop (fluctuation range -0.04MPa) during boiler #3 switchover: T10 minutes: During the depressurization process of boiler #1, the air pressure suddenly dropped to 0.41MPa, triggering a level 2 warning; Emergency Response: Operators should immediately increase the nitrogen flow rate to 20 Nm³ / h in the pressure equalization valve. 3 / h, reduce the valve closing rate of boiler #1 to 5% / min; Results: After 3 minutes, the air pressure rose to 0.43 MPa, with fluctuations controlled within ±0.02 MPa; the furnace replacement operation continued, with the total time extended to 35 minutes, and no abnormalities were found in the blast furnace condition.

[0052] 5. Summary of Implementation Results The method of this invention is at 2500m 3 The HyCROF blast furnace system, equipped with three gas-fired heating furnaces, has been running continuously for three months. The results are as follows: Fluctuation control effect: The air pressure fluctuation amplitude of the three furnace replacement combinations is ≤±0.02MPa and the gas flow fluctuation amplitude is ≤±15%, which are 75% and 40% lower than those of traditional furnace replacement, respectively. Impact on blast furnace: hot metal temperature fluctuation ≤ ±10℃, permeability index fluctuation ≤ ±0.3, unplanned blast furnace shutdown time reduced from 40 hours / month to 5 hours / month, a reduction of 87.5%; Economic benefits: The thermal efficiency of the gas-fired furnace has increased from 85% to 93%, gas consumption has decreased by 13%, the cost per ton of iron has decreased by 18 yuan, and the monthly economic benefit has reached 540,000 yuan. Safety: No safety accidents such as gas leakage, flameout, or backfire occurred during the furnace replacement process, and the CO emission concentration remained stable at ≤300ppm, meeting environmental protection requirements; Operational standardization: The accuracy rate of furnace replacement operation has been improved from 80% to 98%, and the emergency response time of operators is ≤3 minutes.

[0053] 6. Precautions The furnace replacement operation must be avoided during critical periods such as blast furnace blasting and tapping to ensure stable blast furnace operation. If a sudden abnormality occurs in the blast furnace, the furnace replacement operation should be suspended immediately, and priority should be given to ensuring the stable operation of the blast furnace.

[0054] The nitrogen equalization system needs to be checked regularly for sealing and pressure stability to prevent nitrogen leakage from affecting the furnace replacement effect or causing safety risks; the nitrogen purity must be ≥99.9% and the dew point ≤-40℃ to prevent moisture from entering the gas system.

[0055] Operators must strictly follow the standardized procedures to perform furnace changeover operations and must not arbitrarily change key indicators such as equalization parameters and valve switching rates; if adjustments are necessary in special circumstances, they must be approved by the technical supervisor and the reasons and results of the adjustments must be recorded.

[0056] During the furnace replacement process, it is necessary to closely monitor the operating status of the three furnaces and the blast furnace operating parameters. If an early warning signal is issued, the corresponding emergency response procedure should be initiated immediately to prevent the fluctuation from escalating. After the emergency response, the furnace replacement data should be reviewed and analyzed to optimize the early warning threshold and response plan.

[0057] During the continuous optimization process, it is necessary to combine the actual operating status of the three furnaces (such as changes in heat load and equipment aging) with the blast furnace smelting requirements, dynamically adjust the equalization parameters and furnace switching process, and ensure the adaptability and effectiveness of the method.

[0058] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace, characterized in that, Includes the following steps: S1: For 2500m 3 The HyCROF blast furnace was equipped with three gas-fired heating furnaces (No. 1, No. 2, and No. 3) for furnace changeover fluctuation analysis, and a multi-furnace coordinated control system for nitrogen pressure equalization was designed. S2: Develop standardized furnace replacement procedures for different furnace types, including pre-replacement preparation, furnace type switching operations, and post-replacement stability assurance. S3: Establish a multi-dimensional early warning system for furnace changeover fluctuations and an emergency response mechanism for typical operating conditions; S4: Build a stable operation guarantee system that includes equipment maintenance, personnel training, and continuous optimization.

2. The method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace according to claim 1, characterized in that, The nitrogen pressure equalization multi-furnace coordinated control system mentioned in step S1 includes: Nitrogen source configuration: Nitrogen source with purity ≥ 99.9%, 10m 3 Main nitrogen tank, 3 x 3m 3 The pressure of the main nitrogen tank is stabilized at 0.6-0.8 MPa, and the pressure of the branch buffer tank is maintained at 0.45-0.5 MPa through a pressure reducing valve, ensuring a stable nitrogen supply and rapid response. Pressure equalization pipeline layout: Pressure equalization branch pipes are installed 5m away from the gas inlet pipes of boilers 1, 2, and 3, and 3m away from the gas exhaust pipes. The diameter of the pressure equalization branch pipes is 50mm, and they are equipped with intelligent flow regulating valves, pressure sensors, check valves, and sub-pressure equalization valves; and a main pressure equalization valve is installed on the main gas pipe to achieve global pressure balance control. Control system integration: Link the intelligent flow regulating valve, pressure sensor, and sub-pressure equalization valve of the pressure equalization branch pipe with the blast furnace central control platform, and develop a multi-furnace pressure collaborative control module, integrating pressure monitoring, flow regulation, and furnace change logic judgment functions, with a response time of ≤1 second, so as to realize automatic matching of pressure equalization parameters for different furnace change combinations.

3. The method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace according to claim 2, characterized in that, The equalization pressure parameters are: During the furnace replacement process, the system air pressure remained stable at 0.43-0.47 MPa, with a fluctuation range of ≤ ±0.02 MPa, and the inter-furnace pressure difference was ≤ 0.01 MPa. The nitrogen flow rate control for the furnace replacement assembly is as follows: 1# #2 Switching: Depressurization nitrogen flow rate 8-10 Nm 3 / h increments, boosting voltage by 12-15Nm 3 / h decreases, stable at 3-5Nm 3 / h; 2# #3 Switching: Depressurization nitrogen flow rate 10-12 Nm 3 / h increments, boosting voltage by 15-18Nm 3 / h decreases, stable at 4-6Nm 3 / h; 1# #3 Switchover: Pre-pressure equalization 15 minutes before furnace switchover, depressurization 12-15 Nm 3 / h increments, boosting voltage by 18-20Nm 3 / h decreases, stable at 5-7Nm 3 / h.

4. The method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace according to claim 3, characterized in that, The furnace replacement combination durations are as follows: 1# The total switching time for boiler #2 was 25 minutes. 2# The total switching time for boiler #3 was 28 minutes. 1# The total switching time for boiler #3 was 32 minutes.

5. The method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace according to claim 2, characterized in that, During the furnace replacement operation, the opening and closing rate of the gas inlet valve on the gas inlet pipeline is 10% / min.

6. The method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace according to claim 1, characterized in that, The early warning system described in step S3 is configured with two levels of early warning: Level 1 warning: Wind pressure fluctuation ±0.02MPa, flow rate fluctuation ±15%, CO > 500ppm, air permeability index > 4.5; Level II Warning: Wind pressure fluctuation ±0.03MPa, flow rate fluctuation ±20%, CO > 800ppm, air permeability index > 5.0; If the situation is not resolved within 3 minutes of a Level 2 warning, the system will automatically shut down and switch to the original operating furnace.

7. The method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace according to claim 1, characterized in that, The emergency response measures described in step S3 include: Sudden drop in wind pressure: Increase nitrogen flow rate by 5-10 Nm 3 / h, the valve opening and closing rate drops to 5% / min; Sudden increase in air pressure: Reduce nitrogen flow rate, open pressure relief valve, and control pressure to not exceed 0.5 MPa; Unstable combustion: Adjust the air-fuel ratio by 10-15%. If the flame goes out, purge with nitrogen for ≥5 minutes and then reignite. Blast furnace condition fluctuations: Suspend furnace replacement, reduce blast furnace blast by 5-10%, and resume furnace replacement after stabilization.

8. The method for controlling and stabilizing the operation of a gas-fired heating furnace during furnace changeover, as described in claim 1, is characterized in that... The equipment maintenance described in step S4 includes: Daily checks of nitrogen pressure and pipe seals; weekly sensor calibration; quarterly valve disassembly and cleaning; annual cleaning of the furnace and heat exchangers.

9. The method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace according to claim 1, characterized in that, The personnel training mentioned in step S4 includes theoretical training, simulated practice, and case review. Only those who pass the assessment can be assigned to their posts, and the emergency response time is ≤3 minutes.

10. The method for controlling furnace changeover fluctuations and ensuring stable operation of a gas-fired heating furnace according to claim 1, characterized in that, The furnace changeover process must be avoided during the blast furnace blasting and tapping periods; nitrogen dew point ≤ -40℃, system pressure holding 0.5MPa, and pressure drop ≤ 0.005MPa after 30 minutes are considered acceptable.

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