Converter gas lifting lance oxygen content interlocking delay recovery method and system

Abstract

A method and system for delayed recovery of oxygen content in converter gas lances, belonging to the field of metallurgical automation control, is disclosed. This method monitors the oxygen lance position, oxygen shut-off valve status, gas composition, and flow rate in real time. When the oxygen lance exceeds the blowing end height and the oxygen shut-off valve switches from open to closed, a recovery termination signal is triggered, overriding the original hard interlock and activating the delayed recovery logic. A transmission lag time model is established based on pipeline length and flow rate, set as a delay, and the three-way switching valve is controlled to maintain the recovery position. During the delay, oxygen content is monitored with the highest priority, and the blower frequency is maintained to stabilize the negative pressure. When the delay ends or protection conditions are triggered, the system switches to the venting position. The system includes signal acquisition, logic operation, execution control, and safety assurance modules. This application extends the qualified gas recovery window and increases the total recovery volume while ensuring safety through fluid dynamics compensation and dynamic monitoring.

Description

Technical Field

[0001] This application belongs to the field of metallurgical automation control, specifically relating to a method and system for interlocking delayed recovery of oxygen content in converter gas lifting lance. Background Technology

[0002] With the deepening of the green and low-carbon transformation of the steel industry, converter gas recovery and utilization technology has become a core link for steel enterprises to save energy, reduce consumption and carbon emissions. As a by-product of the steelmaking process, converter gas contains combustible components with high calorific value. Its recovery efficiency directly affects the optimization of the enterprise's energy structure and environmental benefits. In automated steelmaking systems, the gas recovery control logic needs to take into account both maximizing resource recovery and production process safety. Through precise control of parameters at each stage of blowing, the effective capture and classification of gas components can be achieved.

[0003] Among them, the interlock control logic of the converter gas recovery system at the end of the blowing process is the key to determining the total amount of gas recovered. Under normal circumstances, the recovery system automatically switches between recovery and venting states at the end of the blowing process by monitoring the oxygen lance status, valve opening and closing signals and gas composition indicators. This step requires the control system to be able to respond instantaneously to process signals to ensure that the effective gas recovery time is extended as much as possible while meeting safety thresholds, thereby increasing the total amount of gas recovered from a single furnace.

[0004] However, the recycling interlock logic in the existing technology is too mechanical. It usually takes the oxygen lance lifting and oxygen valve closing signal at the end of the blowing process as the absolute trigger condition for the termination of recycling, which results in a large amount of qualified gas within the safety threshold being forcibly released.

[0005] This simplistic logical judgment ignores the physical flow characteristics and lag of composition changes of residual gas in the pipeline, resulting in significant energy waste. At the same time, traditional control strategies lack dynamic buffering for oxygen content fluctuations, making it impossible to maximize the exploitation of residual energy at the end of the blowing process while ensuring system safety.

[0006] Furthermore, there is a logical disconnect between the existing venting switching mechanism and real-time gas composition monitoring, making it difficult to balance recovery rate and safety under complex and ever-changing operating conditions.

[0007] Therefore, a delayed recovery scheme for oxygen content in converter gas lance is desired. Summary of the Invention

[0008] The purpose of this invention is to provide a method and system for interlocking delayed recovery of oxygen content in converter gas lances, which can effectively solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect is a method for interlocked delayed recovery of oxygen content in converter gas lances, as disclosed in this application, comprising the following steps: S1. Real-time monitoring of process status signals at the end of converter blowing, wherein the process status signals include at least oxygen lance position signal, oxygen shut-off valve status signal, gas composition signal in recovery pipeline, and real-time flow rate signal in pipeline.

[0010] S2. When the oxygen lance position signal is detected to exceed the preset blowing end height threshold and the oxygen shut-off valve status signal changes from open to closed, it is identified as the initial trigger signal for the termination of recovery. In response to the initial trigger signal, the instruction overwrite operation is executed, the original hard interlock program that triggers the three-way switching valve to the venting position immediately based on the oxygen lance lifting action is suspended, and the delayed recovery logic is activated.

[0011] S3. Activate the delayed recovery logic, obtain the real-time flow velocity signal in the pipeline, construct a gas transmission lag time calculation model based on the preset pipeline length, calculate the transmission lag time, set the transmission lag time to a preset duration, and simultaneously control the three-way switching valve to remain in the recovery position.

[0012] S4. During the delayed recovery period, perform dynamic safety logic monitoring, including at least real-time monitoring of oxygen content with the highest priority and controlling the blower to maintain the current recovery frequency to keep the pipeline negative pressure stable.

[0013] S5. When the preset time expires or the safety dynamic logic monitoring triggers the protection condition, the state switching and safety interlock response are executed according to the monitoring result, and the three-way switching valve is controlled to switch to the venting position.

[0014] Preferably, step S3, controlling the three-way switching valve to remain in the retracted position, specifically includes: By overriding software instructions, after recognizing the initial trigger signal, an internal memory bit, namely the delayed recovery activation flag bit, is set to 1. In the program loop, the original immediate release instruction stream is skipped, and the output point of the digital output module used to drive the solenoid valve of the three-way switching valve is kept in the set state, so that the valve plate of the three-way switching valve is kept in the recovery position.

[0015] Preferably, the gas transmission lag time calculation model in step S3 specifically includes: The physical distance between the gas generation point at the furnace mouth and the sampling point before the three-way switching valve is obtained as the pipeline length. Combined with the real-time flow velocity of the gas in the pipeline obtained by real-time measurement through a vortex flow meter or Pitot tube flow meter, the transmission lag time is calculated.

[0016] Preferably, step S4, which involves real-time monitoring of oxygen content with the highest priority, further includes: The control system establishes a sliding window data buffer to store oxygen concentration values ​​from the most recent multiple sampling periods. By calculating the first derivative of the oxygen concentration values ​​within the sliding window, it predicts the trend of oxygen content change. When the first derivative exceeds a preset rate of change threshold, it outputs an early warning signal.

[0017] Preferably, the security dynamic logic monitoring in step S4 further includes: The instantaneous pressure of the recovery pipeline is monitored synchronously. When the pipeline pressure is detected to be below 0.5 kPa, it is determined that there is a risk of air intake and the protection mechanism is triggered.

[0018] Preferably, the security dynamic logic monitoring in step S4 further includes: The carbon monoxide concentration is assessed in real time. When the carbon monoxide concentration is detected to be below the calorific value threshold of 35%, the early termination delay procedure is triggered according to the principle of energy efficiency priority.

[0019] Preferably, the execution state switching and safety interlock response in step S5 specifically includes: When the delay timer reaches the preset duration and the oxygen content remains below the safety threshold of 1% and the carbon monoxide concentration remains above the calorific value threshold of 35% throughout the entire delay period, the normal switching process is executed. This involves de-energizing the hydraulic solenoid valve of the three-way switching valve and driving the valve plate to move from the recovery position to the venting position.

[0020] Preferably, step S5, which involves executing the state transition and safety interlock response, specifically includes: If any of the following abnormal conditions are detected during the delay period: oxygen content reaches or exceeds the safety threshold of 1%, pipeline pressure is below 0.5 kPa, or carbon monoxide concentration is below the calorific value threshold of 35%, the delay timer is immediately interrupted and forced venting mode is entered. Through the dual redundancy mechanism of software-level interrupt handling and hardware-level hard-wired interlocking circuit, the three-way switching valve is controlled to switch to the venting position with the highest priority.

[0021] Preferably, the hardware-level hardwired interlocking circuit specifically includes: An independent hard-wired interlocking circuit is formed by a safety relay. The input side of the safety relay is connected to the alarm relay and the emergency stop button on the control panel of the online laser gas analyzer. The output contact is connected in series in the power supply circuit of the three-way switching valve solenoid valve. When an oxygen content exceeding the limit signal or an emergency stop signal is received, the safety relay directly cuts off the power supply to the solenoid valve, forcing the three-way switching valve to reset to the venting position.

[0022] Secondly, the converter gas lance oxygen content interlocking delayed recovery system disclosed in this application includes: a signal acquisition module for real-time monitoring of process status signals at the end of converter blowing. The signal acquisition module includes at least: an absolute multi-turn encoder installed at the end of the oxygen lance hoisting system drum shaft for acquiring oxygen lance position signals; a dual-redundant limit switch installed on the oxygen shut-off valve actuator for acquiring oxygen shut-off valve status signals; an online laser gas analysis system installed at the sampling point upstream of the three-way switching valve at the end of the recovery pipeline for acquiring gas composition signals in the recovery pipeline; and a vortex flow meter or Pitot tube flow meter installed in the flue or pipeline for acquiring real-time flow velocity signals in the pipeline.

[0023] The logic operation module includes a programmable logic controller (PLC). The PLC is configured to: when the oxygen lance position signal exceeds a preset blowing end height threshold and the oxygen shut-off valve status signal changes from open to closed, identify it as the initial trigger signal for termination of recovery, and execute an instruction overwrite operation to suspend the original hard interlock program that triggers the three-way switching valve to the venting position immediately based on the oxygen lance lifting action, and activate the delayed recovery logic; start the delayed recovery logic, acquire the real-time flow velocity signal in the pipeline, calculate the transmission lag time based on the preset pipeline length and set it as a preset duration; during the delayed recovery period, perform dynamic safety logic monitoring and control the blower to maintain the current recovery frequency.

[0024] The execution control module includes a hydraulic station control unit for driving the three-way switching valve and a solenoid valve drive circuit. The execution control module responds to the instructions of the logic operation module, controls the valve plate of the three-way switching valve to remain in the retracted position for a preset time period, and controls the three-way switching valve to switch to the release position when the preset time period ends or when the safety dynamic logic monitoring triggers the protection condition.

[0025] The safety protection module includes a hard-wired interlocking circuit composed of safety relays. The input side of the safety relays is connected to the alarm relay of the online laser gas analyzer, and the output side contacts are connected in series in the power supply circuit of the solenoid valve drive circuit. This is used to directly cut off the power supply to the solenoid valve when the logic operation module fails or the oxygen content exceeds the limit.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. This application overcomes the problem of qualified gas being forcibly released due to the immediate triggering of release when the oxygen lance is lifted in the traditional interlocking logic by introducing a delayed recovery control method based on fluid dynamics compensation. After the initial trigger signal for the termination of recovery appears, the original hard interlocking program is suspended by an instruction, and the transmission lag time is calculated and a delay is set based on the pipeline length and real-time flow velocity, so that the residual qualified gas in the pipeline can continue to be recovered, which significantly improves the total amount of gas recovered from a single furnace.

[0027] 2. This application establishes a dynamic safety monitoring mechanism with oxygen content as the highest priority during the delayed recovery period. Combined with a sliding window data buffer and trend prediction, it can provide early warnings before the oxygen content reaches the threshold. At the same time, by synchronously monitoring pipeline pressure and carbon monoxide concentration, a multi-dimensional safety protection system is constructed to effectively prevent safety risks and economic losses caused by air intake or low gas calorific value.

[0028] 3. This application achieves seamless integration of delayed recovery logic and original safety protection mechanism through dual redundancy design of instruction overriding at the software level and hard-wired interlocking circuit at the hardware level. While ensuring the flexibility of the control system, it ensures that the three-way switching valve can be forcibly switched to the venting position with the highest priority in extreme working conditions or system failure, thus taking into account both recovery efficiency and production safety.

[0029] 4. By maintaining the operation of the blower at the current recovery frequency during the delayed recovery process, this application ensures the stability of the pipeline negative pressure and avoids process problems such as gas backflow or furnace smoke caused by blower speed fluctuations. While extending the recovery window period, it also ensures the stable operation of the dust removal system and pipeline network, providing reliable technical support for the efficient and safe operation of the converter gas recovery system under complex working conditions. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall technical solution architecture of the converter gas lance oxygen content interlocking delayed recovery method of this application; Figure 2 This is a schematic diagram of the recycling termination trigger determination and initial signal identification process in this application; Figure 3 This is a schematic diagram of the delayed recovery logic startup and transmission lag time calculation process in this application; Figure 4 This is a schematic diagram of the security dynamic logic monitoring process of this application; Figure 5 This is a schematic diagram of the state switching and safety interlock response process of this application. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0032] In the field of converter gas recovery technology, the energy utilization rate can be deeply explored by precisely controlling the parameters at the end of the steelmaking process. This embodiment provides a converter gas lance oxygen content interlocking delayed recovery method and system. By reconstructing the automatic control logic, the effective gas recovery window period is extended while ensuring production safety.

[0033] See Figures 1 to 5 For step S1 of the method for interlocking delayed recovery of oxygen content in converter gas lance, the steelmaking process status signal is monitored in real time, and its specific implementation process is as follows: In step S101, the automated control system collects key operating condition data from the converter blowing site through distributed input / output modules using a high-frequency sampling method, building a basic data pool for subsequent logical judgments. These key operating condition data include at least the real-time position signal of the oxygen lance, the opening and closing status signal of the oxygen shut-off valve, the instantaneous flow rate of oxygen, oxygen pressure, nitrogen sealing flow rate, and flue gas composition analysis data in the converter.

[0034] In step S102, at the signal acquisition level of the oxygen lance position status, the system uses an absolute multi-turn encoder installed at the end of the drum shaft of the oxygen lance hoisting system to obtain the oxygen lance position information. The encoder transmits the absolute height value of the oxygen lance to the core processor composed of a programmable logic controller (PLC) in real time through fieldbus protocols such as PROFINET or PROFIBUS-DP.

[0035] When the oxygen lance starts to rise from the blowing position, the encoder value changes continuously. The system calculates the rate of change of this value and combines it with the current absolute position to determine whether the oxygen lance has entered the lifting stage. The specific determination logic is as follows: the system presets a position change rate threshold. When the absolute value of the encoder value change rate continuously exceeds the threshold and the current absolute position is within the preset range from the blowing position to the standby position, it is determined that the oxygen lance has entered the lifting stage.

[0036] This rate of change threshold can be calculated based on the relationship between the motor speed of the hoisting system and the number of encoder pulses, for example, it can be set to 50 encoder pulses per second.

[0037] In step S103, at the level of acquiring the opening and closing signal of the oxygen shut-off valve, the system captures the signal through the limit switch on the valve actuator and adopts a dual-loop redundancy design to ensure the reliability of the signal. Specifically, two inductive switches are set at the opening and closing positions of the valve.

[0038] These two inductive switches are mechanical or proximity limit switches. Their contacts are independent of each other, forming two completely isolated signal loops, which are respectively connected to two different input modules of the automation control system or two different channels of the same input module.

[0039] When the oxygen valve is interlocked and closed, the contacts of the two closing limit switches close, sending a 24-volt DC signal to the automatic control system. The system's internal debounce filtering program processes the signal to filter out instantaneous interference caused by mechanical vibration, thereby ensuring the accuracy of the valve closing status determination.

[0040] The specific implementation of the debouncing filter program is as follows: a fixed signal stabilization time window is set, such as 50 milliseconds. The system continuously monitors the input signal of the limit switch. Only when the signal remains stable at a high level within the time window is the signal confirmed as valid and the valve position flag is updated. If the signal jitters or jumps within the window, the original state is maintained and the judgment is made after the signal stabilizes.

[0041] In step S104, regarding the data acquisition of carbon monoxide concentration and oxygen content within the recovery pipeline, the system is equipped with an online laser gas analysis system at the sampling point at the end of the recovery pipeline, i.e., before the three-way switching valve. This system serves as the core indicator source for evaluating the value and safety of coal gas recovery.

[0042] The sampling point is specifically set about 1 to 2 meters upstream of the three-way switching valve, at a distance of about 1 meter to 2 meters from the valve body inlet. This location can accurately reflect the composition of the gas that is about to enter the switching valve, providing the most direct basis for the switching decision between recovery and release.

[0043] Step S105: The online laser gas analysis system consists of three parts: a sampling probe, a pretreatment unit, and the analyzer main unit. The sampling probe adopts an insertion-type installation structure, with the probe tip extending into the central area of ​​the pipeline, where the gas flow rate is stable and representative.

[0044] The sampling probe has an electric heating function, with the heating temperature controlled between 120 and 150 degrees Celsius. This is to prevent moisture in the gas from condensing inside the probe and clogging the filter element or affecting the measurement accuracy. The pretreatment unit uses multi-stage filtration and cold drying. First, it filters out particles larger than 5 micrometers through a first-stage stainless steel sintered filter element, and then filters out dust particles larger than 0.1 micrometers through a second-stage precision filter element.

[0045] The sample gas temperature is then reduced to about 4 degrees Celsius using an electronic cooling condenser, causing moisture to condense and precipitate. Finally, the clean and dry gas to be tested is sent to the main unit of the analyzer. The output pressure of the pretreatment unit is stabilized between 0.1 MPa and 0.2 MPa, and the flow rate is controlled between 1 liter and 2 liters per minute to ensure that the analyzer performs measurements under stable operating conditions.

[0046] Step S106: The analyzer host integrates two independent measurement modules, which use different principles to measure the concentration of the two gases. The laser oxygen content analysis module uses tunable diode laser absorption spectroscopy technology. It emits a laser beam of a specific wavelength, which corresponds to the characteristic absorption spectral line of oxygen molecules. After the laser beam passes through the gas to be measured, it is received by a photodetector. According to the Lambert-Beer law, the oxygen concentration is exponentially related to the attenuation of the laser intensity. The oxygen concentration value can be calculated by measuring the attenuation.

[0047] The module's response time is down to the millisecond level, enabling it to capture rapid changes in oxygen concentration in real time. The carbon monoxide concentration monitoring module uses the principle of non-dispersive infrared analysis, with an infrared light source and two infrared detectors. One detector is equipped with a narrowband filter corresponding to the characteristic absorption peak of carbon monoxide, and the other detector is equipped with a reference filter that does not absorb carbon monoxide. The carbon monoxide concentration is calculated by measuring the difference in infrared radiation intensity received by the two detectors and combining it with Lambert-Beer's law.

[0048] Then, each of the two measurement modules outputs an analog signal proportional to the gas concentration. The signal type is a standard industrial signal of 4 mA to 20 mA current or 0 V to 10 V voltage. The analog signal is converted into a 16-bit or higher resolution digital quantity by the analog input module and stored in the register of the programmable logic controller for real-time call by the logic operation program.

[0049] Through the above steps S101 to S106, this method completes the comprehensive real-time monitoring of key process status signals at the end of converter blowing, covering three core dimensions: oxygen lance position, valve status, and gas composition. This lays a reliable data foundation for determining the initial triggering conditions for subsequent recovery termination and for the accurate execution of delayed recovery logic.

[0050] In step S2 of the converter gas lance oxygen content interlocking delayed recovery method, the initial trigger condition for recovery termination is determined, and its specific implementation process is as follows: In step S201, the logic judgment unit of the automated control system polls in real time the various process status signals collected in step S1, including the oxygen lance height signal and the oxygen shut-off valve closing limit signal, and performs continuous logical comparison on these signals.

[0051] The logic judgment unit is executed by the central processing unit of the programmable logic controller. Its polling cycle is synchronized with the program scan cycle of the PLC, and is usually set between 10 milliseconds and 50 milliseconds to ensure that the system can respond to changes in process status in a timely manner.

[0052] In step S202, the system compares the current oxygen lance height with the preset blowing end height threshold. The blowing end height threshold is determined during the converter process debugging stage based on the safe distance between the oxygen lance nozzle and the molten pool surface. The typical value is 3 to 5 meters above the original blowing position of the oxygen lance.

[0053] The system simultaneously monitors whether the closing limit signal of the oxygen shut-off valve changes from the open state to the closed state. This closing limit signal comes from two independent inductive switches set in step S103. The system confirms that the valve is actually closed by comprehensively judging the redundant signals. The specific judgment logic is: when the states of the two closing limit switches are both closed after debounce filtering, it is determined that the oxygen valve has completed the interlocking closing action.

[0054] The system recognizes the following two conditions as the initial trigger signal for termination of recycling: First, the oxygen lance height exceeds the preset blowing end height threshold, indicating that the oxygen lance has been raised to the blowing end position and the blowing process has been terminated; Second, the oxygen shut-off valve's closing limit signal changes from open to closed, indicating that the oxygen valve has completed the interlocking closing action and the oxygen supply has been cut off.

[0055] The two conditions usually occur almost simultaneously in terms of timing, but the system requires that both conditions be met before the initial trigger signal is considered valid, in order to eliminate false triggering caused by a single signal malfunction.

[0056] In step S203, after recognizing the initial trigger signal, the control system executes a command overriding operation. The system automatically suspends the original hard interlock program that triggers the three-way switching valve to the venting position immediately upon the oxygen lance lifting action, and replaces it with the delayed recovery logic of this embodiment.

[0057] The specific implementation of the instruction override operation is as follows: In the PLC's program organization unit, the immediate release instruction block, originally used to control the three-way switching valve, is configured to be conditionally maskable. After receiving the initial trigger signal, the system sets an internal memory bit, namely the delay recovery activation flag, to 1.

[0058] In the main program loop, the system determines which control logic to execute by judging the state of the flag: when the flag is 0, the original immediate release logic is executed; when the flag is 1, the original immediate release logic is skipped and the delayed recycling logic block is executed instead.

[0059] This design enables dynamic switching of control logic through software programming without modifying the original hard interlock hardware wiring. Although the original hard interlock program, which was based on the oxygen lance lifting action immediately triggering the three-way switching valve to the venting position, is suspended at the software level, its underlying hardware safety circuit remains effective as the final safety protection barrier.

[0060] Step S204, the instruction overriding operation is implemented in the software logic layer of the controller, specifically by setting the intermediate variable flag bit. When the initial trigger signal identified in step S202 takes effect, the system sets the flag bit, i.e., the delay recovery activation flag bit, to logic 1. This flag bit is used as a global variable in the PLC's program organization unit, and its scope covers the entire delay recovery logic program block.

[0061] During a normal program scan cycle, the system checks the current status of this flag bit in each cycle. When the flag bit is 0, the system executes according to the original control logic, that is, once an oxygen lance lifting signal or an oxygen valve closing signal is detected, it immediately outputs a command to switch the three-way switching valve to the venting position.

[0062] When the flag is set to 1, the system performs a conditional jump on the program execution path. The original immediate release instruction stream is conditionally shielded, and no switching instructions are output to the execution control module. At this time, the solenoid valve of the three-way switching valve remains energized, and the valve plate remains in the retracted position, so that the three-way switching valve, which would have immediately switched to the release position when the oxygen lance is lifted, continues to remain in the retracted position at the current moment.

[0063] This software-level instruction overriding design does not modify the hardware wiring of the underlying hard-interlocking circuit, ensuring that physical safety protection remains effective even in extreme cases.

[0064] In step S205, with the three-way switching valve in the recovery position, the gas continues to be transported along the original path through the flue, cooler, dust collector, fan and other equipment towards the gas holder.

[0065] Since the oxygen lance has been raised and the oxygen valve has been closed, the blowing reaction has ended. However, the gas that has been generated in the pipeline and is in the process of being transported is still qualified gas with high calorific value and low oxygen content. This part of the gas needs to go through a period of transmission time after it is generated from the furnace mouth before it reaches the three-way switching valve.

[0066] By keeping the three-way switching valve in the recovery position, the system provides an additional recovery time window for the qualified gas that is in the process of transmission, allowing the qualified gas that would otherwise be released at the moment of lifting the nozzle to enter the gas holder for recovery, thereby increasing the total amount of gas recovered from a single furnace. The length of this time window is determined by Δt obtained from the gas transmission lag time calculation model in steps S303 to S304, ensuring that the recovery is completed before the gas composition deteriorates.

[0067] Through the above steps S201 to S205, this method effectively covers the traditional recycling termination logic. Without changing the original hard interlock protection mechanism, the timing of recycling termination is delayed from the moment the oxygen lance is lifted to the moment when the delayed recycling logic is completed or the safety condition is broken through the logic intervention at the software level, thus creating the necessary conditions for the subsequent operation of the delayed recycling program.

[0068] For step S3 in the interlocked delayed recovery method for oxygen content in converter gas lifting lance, the delayed recovery logic control program is initiated, and its specific implementation process is as follows: In step S301, the control system immediately activates an internal high-precision timer the instant it detects the rising edge of the initial trigger signal for the recycling termination mentioned in step S202. This timer is implemented by the system clock or a dedicated timing function block inside the programmable logic controller, and the timing resolution is usually 10 milliseconds, used to control the duration of the delayed recycling.

[0069] The preset duration is determined based on the gas transmission lag time calculated from the converter gas fluid dynamics characteristics in subsequent steps, rather than a fixed empirical value, thereby achieving adaptive matching for different operating conditions.

[0070] In step S302, the system takes into account the inherent transmission delay that exists in the complete physical transmission process of gas from the converter furnace mouth through the flue, vaporization cooling flue, primary dust removal system, secondary dust removal system, fan and other equipment until it reaches the three-way switching valve.

[0071] When the oxygen shut-off valve is closed and the blowing stops, the gas that has been generated in the pipeline and is still in the process of transmission is still qualified gas with high calorific value and low oxygen content. This part of the gas has recycling value. Since the gas needs a certain amount of time to flow in the pipeline, the transmission path length from the furnace mouth to the three-way switching valve is usually 100 to 200 meters, and the corresponding transmission time is about 5 to 15 seconds. This window period is the core period for delayed recycling.

[0072] In step S303, in order to accurately calculate the time required for the qualified gas to completely pass through the three-way switching valve, the system introduces a gas transmission lag time calculation model. This model uses pipeline length and real-time flow velocity as core parameters. The pipeline length L represents the physical distance between the gas generation point at the furnace mouth and the sampling point before the three-way switching valve, in meters. This value is set once during system initialization based on the actual pipeline length on site, and the value range is usually from 80 meters to 250 meters.

[0073] The real-time flow velocity v is obtained by a vortex flow meter or pitot tube flow meter installed in the flue or pipe. The unit is meters per second. The measurement cycle is synchronized with the PLC scanning cycle, which is usually 100 milliseconds to 500 milliseconds. The flow velocity data is collected in real time before the delayed start to ensure that the flow velocity value used for calculation is consistent with the actual flow velocity in the pipe at the time of delayed start.

[0074] Step S304: The system calculates the transmission lag time Δt based on the gas transmission lag time calculation model. The specific calculation formula is as follows: ; Where η is the fluid Reynolds number correction coefficient, with a value ranging from 0.85 to 0.95. This coefficient is used to compensate for the influence of friction on the inner wall of the pipeline and local resistance such as elbows and valves on the actual flow velocity distribution, so that the calculation results are closer to the actual gas transmission time.

[0075] In step S305, the control system sets the transmission lag time Δt calculated in step S304 as a preset duration into the high-precision timer, and the timer starts counting down. During the entire timing period, the control system keeps the solenoid valve of the three-way switching valve energized. After the solenoid valve is energized, it drives the hydraulic oil in the hydraulic system to flow to the retraction position oil circuit, pushing the hydraulic cylinder to move the valve plate to stay in the retraction position, thereby ensuring that the three-way switching valve is continuously in the retraction state.

[0076] The energization state of the solenoid valve is directly controlled by the digital output module of the PLC. The output channel is configured with fault-safe characteristics. When the PLC program is running normally, it outputs a high-level signal to energize the solenoid valve. When the PLC malfunctions or the program executes forced release logic, it outputs a low-level signal to de-energize the solenoid valve. The valve then relies on spring reset or automatically switches to the release position by counterweight.

[0077] During the delay period, the system continuously maintains the set state of the output point through program loops to ensure that the three-way switching valve does not malfunction due to temporary interruptions during the program scan cycle.

[0078] Step S306: Throughout the entire operation of the delay timer, the system maintains the fan speed at the current recovery frequency. Specifically, the PLC sends a 4mA to 20mA current signal or a 0V to 10V voltage signal corresponding to the current recovery frequency to the fan inverter via an analog output module. The inverter maintains the fan motor at a fixed speed based on this setting.

[0079] Maintaining a stable fan speed ensures a relatively stable flow and pressure of gas in the pipeline. Stabilizing the pipeline pressure prevents gas backflow or smoke from the furnace mouth caused by significant fan deceleration or shutdown. Smoke from the furnace mouth refers to the phenomenon where flue gas overflows from the converter furnace mouth into the workshop environment due to insufficient negative pressure in the pipeline. This not only causes gas loss but also affects operational safety and environmental compliance.

[0080] The system maintains the pipeline negative pressure at the level required for normal recovery by locking the fan frequency at the current value, ensuring that the delayed recovery process takes place under stable process conditions. Only after the delay timer expires or when forced venting is triggered will the system switch the fan speed to the frequency value corresponding to the venting state according to subsequent steps.

[0081] Through the above steps S301 to S306, this method, based on the gas transmission lag time calculation model, accurately sets the duration of delayed recovery and maintains the stability of key equipment during the delay period, creating a complete recovery window for qualified gas that has been generated in the pipeline but has not yet reached the three-way switching valve, thereby maximizing the recovery time of effective gas while ensuring process safety.

[0082] For step S4 of the converter gas lance oxygen content interlocking delayed recovery method, dynamic safety logic monitoring is performed, and its specific implementation process is as follows: In step S401, during each scan cycle of the delay timer, the system prioritizes real-time monitoring of oxygen content as the highest-priority monitoring task, sampling oxygen concentration data frequently. Specifically, at the beginning of each program scan cycle, the PLC executes the oxygen concentration data acquisition program segment first, reading the oxygen concentration signal output by the online laser gas analyzer through the analog input module. The sampling period is synchronized with the PLC scan cycle, typically set to 10 to 50 milliseconds to ensure timely capture of rapid changes in oxygen concentration.

[0083] In step S402, when monitoring oxygen content, the system not only focuses on its absolute value, but also analyzes its changing trend. To this end, the control system establishes a sliding window data buffer, which stores the oxygen concentration values ​​of the most recent 10 sampling periods.

[0084] The sliding window is implemented as follows: Define an array of length 10 in the PLC's data block. After each sampling, write the new data to the head of the array. The original data in the array are moved to the right in turn. Remove the oldest data to keep the buffer containing the oxygen concentration values ​​of the most recent 10 samples. When the number of samplings is less than 10, the buffer is filled with the actual number of samplings.

[0085] In step S403, the system predicts whether the oxygen content shows a rapid upward trend by calculating the first derivative of the oxygen concentration value within the sliding window. The calculation of the first derivative adopts the central difference method or the forward difference method. Specifically, for continuous sampling points within the sliding window, the difference between two adjacent points is calculated and divided by the sampling time interval to obtain the average rate of change within that time period.

[0086] Then, the average of the most recent rates of change is taken as the approximation of the current first derivative. The larger the positive value of the first derivative, the faster the oxygen content increases. Based on this, the system can predict potential safety risks in advance. For example, when the first derivative exceeds the preset rate of change threshold, such as 0.2% per second, the system will output a warning signal even if the current absolute value of oxygen concentration has not yet reached the safety threshold, so as to buy time for subsequent switching.

[0087] In step S404, the system sets a preset safety threshold for oxygen content of 1%, which is far below the limit concentration for gas explosions and represents a stringent safety limit. Once the real-time oxygen content data reaches or exceeds this threshold, the logic comparison unit immediately outputs a high-level alarm signal.

[0088] The alarm signal triggers the forced release logic within the PLC on one hand, and directly connects to the safety relay of the safety protection module through a hard-wired circuit on the other hand, realizing dual interlocking protection of software and hardware. The reading of oxygen concentration data and threshold comparison are completed within each scan cycle, ensuring that the delay from exceeding the concentration limit to triggering the response does not exceed one scan cycle.

[0089] In step S405, the system synchronously monitors the instantaneous pressure of the recovery pipeline. Since no fresh gas is generated during the delayed recovery phase, the pipeline pressure will show a slow downward trend. When the pressure sensor detects that the pipeline pressure is below 0.5 kPa, the system determines that there is a risk of air intake and triggers the protection mechanism.

[0090] The sampling period of the pressure sensor is synchronized with the oxygen concentration sampling. Its signal is connected to the PLC through the analog input module. The pressure threshold of 0.5 kPa is set based on the following: when the pipeline pressure is lower than this value, outside air may be drawn into the system through the furnace opening or the pipeline if it is not tight. After mixing with the gas, it will form an explosive mixture. When the pressure value is lower than the threshold, the system will immediately set the forced venting flag and trigger the three-way switching valve to switch to the venting position.

[0091] The two conditions, abnormal pressure and excessive oxygen, are independent of each other. The protection is triggered when either condition is met, forming a redundant safety monitoring system.

[0092] Step S406, safety monitoring also includes real-time assessment of carbon monoxide concentration. The system compares the current carbon monoxide concentration with a preset calorific value threshold, which is set at 35%. This value is a critical value determined based on the calorific value characteristics of converter gas. When the carbon monoxide concentration is below 35%, the calorific value of the gas decreases significantly, reducing the economic benefits of recovery.

[0093] The system continuously monitors the carbon monoxide concentration during the delay timer operation. Once the carbon monoxide concentration is detected to be below the threshold, it is determined that the energy value of the recovered coal gas is low, and the system terminates the delay program in advance according to the principle of energy efficiency priority.

[0094] The specific implementation method is as follows: The PLC reads the carbon monoxide concentration signal output by the online laser gas analyzer through the analog input module. In each scanning cycle, the value is compared with the preset 35% threshold. When the carbon monoxide concentration is lower than the threshold, the system immediately sets the forced venting flag, interrupts the delay timer, and triggers the three-way switching valve to switch to the venting position, stopping the recovery of this part of low-calorific-value gas.

[0095] This mechanism ensures that only qualified gas with high economic value is recycled during the delayed recycling phase, avoiding the impact on the overall recycling efficiency due to the recycling of low-calorific-value gas, while also allowing more preparation time for subsequent smelting cycles.

[0096] Through the above steps S401 to S406, this method establishes a multi-level, multi-dimensional dynamic logic monitoring mechanism for safety during the delayed recovery period. It monitors the absolute value of oxygen content and its changing trend, pipeline pressure status, and carbon monoxide concentration level in real time with the highest priority. When any safety condition is broken, a protection response is immediately triggered, providing a rigorous safety guarantee for the delayed recovery process.

[0097] For step S5 of the converter gas lance oxygen content interlocking delayed recovery method, the specific implementation process of triggering state switching and safety interlocking response is as follows: In step S501, the system distinguishes between two different state switching modes based on the running result of the delay timer and the condition judgment result of the dynamic safety monitoring. It executes the normal switching process or the forced release process respectively. The judgment logic of the state switching mode is executed in each scan cycle in the PLC program. When the delay timer has not reached the preset duration and no safety condition is triggered, the system maintains the delay recovery state.

[0098] When the delay timer reaches the preset duration and the oxygen content remains below the safety threshold of 1% and the carbon monoxide concentration remains above the calorific value threshold of 35% throughout the entire delay period, the system enters the normal switching mode. When any safety condition is broken during the delay period, including excessive oxygen content, pipeline pressure below 0.5 kPa, or carbon monoxide concentration below 35%, the system enters the forced venting mode.

[0099] In step S502, under normal switching mode, when the delay timer reaches the preset duration and during this period the oxygen content is always below the safety threshold of 1% and the carbon monoxide concentration is always above the calorific value threshold of 35%, the system determines that the remaining qualified coal gas in the pipeline has been basically recovered.

[0100] At this time, the timer ends and triggers the three-way switching valve switching program. The specific judgment logic is as follows: when the PLC detects that the delay timer countdown has reached zero, it reads and verifies the two status flags stored during the delay period, namely the oxygen content not exceeding the limit flag and the carbon monoxide concentration not lower than the calorific value threshold flag. When both flags are 1, the system confirms that the normal switching conditions are met and then executes the three-way switching valve switching command.

[0101] This design ensures that the normal switching process is only executed when the gas composition meets safety and calorific value requirements throughout the process, thus avoiding safety risks caused by switching to the normal mode even when abnormalities occur in the middle period.

[0102] Step S503: Execute the control module output switching command to de-energize the hydraulic solenoid valve of the three-way switching valve. After the solenoid valve is de-energized, the hydraulic oil flow direction in the hydraulic system switches from the recovery position oil circuit to the release position oil circuit, and the hydraulic cylinder moves the valve plate to the release position under the spring return force or the action of the counterweight.

[0103] The movement speed of the valve plate is preset by the throttle valve in the hydraulic system. It is usually set to control the switching time of the valve plate from fully open to fully closed or vice versa between 1.5 seconds and 3 seconds to ensure that the valve moves smoothly without generating violent impact. After the valve plate reaches the release position, the three-way switching valve completes the normal switching from the recovery state to the release state.

[0104] After the switching is completed, the PLC outputs a sustaining signal to the solenoid valve through the digital output module to keep the solenoid valve in the de-energized state until the system is reset before the start of the next heat. At the same time, the system confirms that the valve plate has actually reached the release position through the limit switch signal of the three-way switching valve and feeds back the valve position status to the operation interface.

[0105] The above steps S502 to S503 complete the standard switching process after the normal end of the delay timing. Under the premise of ensuring that the gas composition meets the safety and calorific value requirements, the remaining qualified gas in the pipeline is fully recovered and then transferred to the venting state.

[0106] Step S504: In the forced venting mode, when any of the following abnormal situations occur at any time during the delay timer process, the system immediately interrupts the delay timer: the oxygen content monitoring value reaches or exceeds the safety threshold of 1%; abnormal fluctuations occur in the pipeline pressure, for example, when the pressure is lower than 0.5 kPa, it is determined that there is a risk of air intake; abnormal operation of the fan is detected.

[0107] Abnormal wind turbine operation status includes wind turbine inverter failure, wind turbine motor overload tripping, and wind turbine speed feedback deviation from the set value exceeding the preset range, such as greater than 10%. These signals are connected to the PLC through the inverter status word or the motor thermal relay. When the system detects any abnormal condition, it immediately sets the forced release flag, clears the remaining time of the delay timer, and stops the delay recovery process.

[0108] In step S505, the safety interlock response has the highest execution priority. Its instruction stream skips all intermediate logic and bypasses the regular program loop scan cycle, directly acting on the actuator.

[0109] The specific implementation methods include two aspects: interrupt handling at the software level and direct control at the hardware level. At the software level, the PLC configures the forced release logic as an interrupt program. This interrupt program is independent of the main program loop. Once the forced release flag is set, the interrupt response is triggered immediately. The interrupt program directly outputs the three-way switching valve switching command to the execution control module, which is not affected by the main program scan cycle.

[0110] At the hardware level, the hard-wired interlocking circuit of the safety protection module is connected in parallel with the forced venting signal. When the oxygen content exceeds the limit signal, the power supply to the solenoid valve is directly cut off via the safety relay, regardless of the PLC program's state, the solenoid valve immediately loses power. These two mechanisms work together to ensure that the three-way switching valve switches to the venting position as quickly as possible, guiding substandard or potentially hazardous gas to the venting tower for combustion. The total response time from the occurrence of the abnormal condition to the valve plate's initiation of action is typically controlled within 100 milliseconds.

[0111] In step S506, after the switching command is output, the control module starts the status feedback verification function. The system monitors the limit switch signal of the three-way switching valve in real time to confirm whether the valve plate has actually reached the release position.

[0112] The three-way switching valve has two independent proximity switches, installed on the valve body at the retraction and venting positions respectively. When the valve plate reaches the corresponding position, the metal sensing surface triggers the proximity switch to output a high-level signal. After issuing the switching command, the control module continuously reads the status of the venting position limit switch.

[0113] If a signal indicating the release position limit switch is received within the preset time, the switching is confirmed to be successful, the system records the completion of the switching, and resets the relevant flag bits. If no signal is received, the system enters the fault handling procedure.

[0114] Step S507: If the system does not receive the release position signal within a preset 3-second time, it determines that the switching action has failed or the valve is stuck. The 3-second time limit is set based on the fact that the normal switching action of a three-way switching valve usually takes 1.5 to 2 seconds. The 3-second timeout threshold fully covers the normal switching time and takes into account possible slight delays.

[0115] After determining that the switching has failed, the system immediately activates the backup plan, including opening the emergency vent valve to provide an additional venting channel. The emergency vent valve is independent of the three-way switching valve, installed on the bypass of the venting pipeline, and controlled by a separate solenoid valve. Its control signal is output synchronously with or slightly after the switching command of the three-way switching valve, ensuring that the venting channel is opened before the unqualified gas reaches the venting tower.

[0116] At the same time, the system triggers a plant-wide safety alarm, notifying operators to intervene urgently through audible and visual alarms, pop-up windows on the operator station, and SMS push notifications, and recording fault information for subsequent maintenance and analysis.

[0117] Through the above steps S501 to S507, this method realizes two state switching modes after the delayed recovery ends: in the normal switching mode, the transition from recovery to venting is completed smoothly; in the forced venting mode, the recovery path is quickly cut off with the highest priority and the risky gas is directed to the venting tower. At the same time, the state feedback verification and backup protection mechanism are used to ensure the reliability and safety of each switching action.

[0118] This embodiment also relates to a converter gas lance oxygen content interlocking delayed recovery system. This system serves as the hardware carrier of the above method, realizing a deep integration of logic and physical execution.

[0119] The signal acquisition module consists of high-precision sensors distributed throughout the converter site. In addition to the aforementioned encoder, limit switches, and gas analyzer, it also includes differential pressure transmitters before and after the blower, a temperature sensor at the cooler outlet, and a flow meter in the flue.

[0120] The differential pressure transmitter typically has a range of 0 to 10 kPa and is used to determine the operating conditions of the blower; the temperature sensor is a platinum resistance type with a range of 0 to 200 degrees Celsius and is used to monitor the outlet gas temperature of the cooler; the flow meter is a turbine or pitot tube type with a range of 0 to 30 m / s, providing key flow velocity parameters for the transmission hysteresis model. The sensors are connected to the remote I / O station via double-shielded compensated cables, with the inner shield protecting against electromagnetic interference and the outer shield grounded.

[0121] The remote I / O station uses a high-speed backplane bus such as PROFINET or EtherCAT, with a synchronization error of less than 5 milliseconds. Analog signals are processed by a 16-bit analog-to-digital converter, with 4 to 20 mA corresponding to 0 to 27648 and 0 to 10 V corresponding to 0 to 27648, and a resolution of 0 to 65535, which can sensitively capture oxygen content fluctuations at the 0.01% level.

[0122] The logic operation module uses a redundant programmable logic controller. The two controllers operate in hot standby mode. The master controller synchronizes the program status, output data and intermediate variables to the slave controller in real time through a fiber optic synchronization link. The slave controller does not execute the program but continuously updates the output image.

[0123] The main controller sends a heartbeat signal after each scan cycle. If the controller fails to receive a heartbeat for two consecutive cycles or detects a hardware fault, it determines that the main controller has failed and seamlessly takes over control within 20 milliseconds, maintaining the output state unchanged to ensure that the delayed recovery logic is not interrupted due to control system failure. The fiber optic link transmission rate is 1 gigabits per second, guaranteeing the real-time performance and consistency of data synchronization.

[0124] The logic operation module integrates an arithmetic operation block and a logic control block, responsible for performing calculations of the gas transmission lag model, delay timing control, multivariate safety comparison, and fault self-diagnosis. Model calculations are performed according to... Execution, where L is the pipe length, v is the real-time flow rate, and η is a correction factor of 0.85 to 0.95.

[0125] The delay timing is implemented through a PLC timer with a resolution of 10 milliseconds. It can be interrupted by a forced release flag. The multi-variable safety comparison includes comparisons of oxygen concentration with a 1% threshold, pressure with 0.5 kPa, carbon monoxide with a 35% threshold, and abnormal fan status. The results are written to the safety flag for switching logic calls.

[0126] The fault self-diagnosis monitors the encoder communication status, limit switch signal rationality, analog channel range, etc. in each scan cycle. When an abnormality occurs, a diagnostic code is generated and logged, and maintenance personnel are prompted to check.

[0127] The execution control module is responsible for driving the three-way switching valve and includes a hydraulic station control unit and a solenoid valve drive circuit. The hydraulic station maintains the system pressure at 12 to 16 MPa, which is automatically adjusted by a pressure switch and an accumulator with a capacity of 2 to 5 liters to ensure that the pump unit can still provide power for at least one complete switching operation during short-term shutdowns.

[0128] The solenoid valve drive circuit uses a 24V DC power supply and is equipped with an intelligent output module to monitor the load current and output voltage in real time. It also has a coil resistance monitoring function. When the resistance is abnormal, it uploads a fault signal and triggers a maintenance alarm to prevent the coil from burning out.

[0129] The execution control module is also deeply integrated with the converter main control system. It exchanges data through industrial Ethernet or fieldbus, receives information such as the status of the blowing stage and the position of the oxygen lance, feeds back the system operating status, and actively shortens or skips the delay recovery when the main control system determines that the preparation time for the next furnace is insufficient.

[0130] The safety protection module provides physical protection independent of the PLC software logic. Its core is a hard-wired interlocking circuit composed of a set of safety relays. The oxygen content over-limit signal comes from the alarm relay of the gas analyzer. When the oxygen concentration reaches 1%, the contact closes. The emergency stop signal comes from the emergency stop button on the control panel. When pressed, the contact opens.

[0131] The safety relay output contacts are connected in series in the power supply circuit of the three-way switching valve solenoid valve. When an over-limit signal is detected and closed or the emergency stop button is pressed, the DC 24-volt power supply to the solenoid valve is immediately cut off. The valve is forced to reset to the release position by the weight of the counterweight or the spring force. This fail-safe design ensures that the system automatically switches to the safest state under any fault, preventing unqualified gas from entering the gas holder.

[0132] This system is also equipped with a data recording and analysis unit, which runs on an industrial host computer and records the recovery parameters for each heat through a database. The database uses SQL Server or MySQL, and the data tables include fields such as heat number, steel type, oxygen lance lifting time, oxygen valve closing time, delay timer setting, real-time change curves of oxygen content and carbon monoxide concentration, pipeline pressure data, and final actual recovery time.

[0133] The data recording unit automatically writes data into the database at the end of each furnace cycle, forming a complete recycling file.

[0134] The system performs in-depth mining and statistical analysis of historical data, groups data by steel type and clusters them by real-time flow rate, calculates the oxygen concentration rise rate and carbon monoxide concentration decay rate through linear regression, and establishes a prediction model for the oxygen content rise rate under different steel types.

[0135] The system periodically runs an optimization program, calculating the average recoverable time for each steel grade every 50 heats or every 72 hours. For low-carbon steel grades, where oxygen content rises more rapidly, the preset delay is set to 90% of the average recoverable time; for high-carbon steel grades, it is set to 100% of the average recoverable time or slightly higher.

[0136] The optimized delay setpoint is automatically updated to the PLC timer for subsequent furnace production, and the changes before and after optimization are recorded for future reference. This adaptive adjustment upgrades the delay recovery logic from a static preset to a dynamic intelligent control mode, further improving the system's flexibility and recovery efficiency.

[0137] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects.

[0138] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for interlocked delayed recovery of oxygen content in converter gas lances, characterized in that: Includes the following steps: S1. Real-time monitoring of process status signals at the end of converter blowing, wherein the process status signals include at least oxygen lance position signal, oxygen shut-off valve status signal, gas composition signal in recovery pipeline and real-time flow rate signal in pipeline. S2. When the oxygen lance position signal is detected to exceed the preset blowing end height threshold and the oxygen shut-off valve status signal changes from open to closed, it is identified as the initial trigger signal for the termination of recovery. In response to the initial trigger signal, the instruction overwrite operation is executed, the original hard interlock program that triggers the three-way switching valve to the venting position immediately based on the oxygen lance lifting action is suspended, and the delayed recovery logic is activated. S3. Activate the delayed recovery logic, obtain the real-time flow velocity signal in the pipeline, construct a gas transmission lag time calculation model based on the preset pipeline length, calculate the transmission lag time, set the transmission lag time to a preset duration, and control the three-way switching valve to remain in the recovery position. S4. During the delayed recovery period, perform dynamic safety logic monitoring, including at least real-time monitoring of oxygen content with the highest priority and controlling the blower to maintain the current recovery frequency to keep the pipeline negative pressure stable. S5. When the preset time expires or the safety dynamic logic monitoring triggers the protection condition, the state switching and safety interlock response are executed according to the monitoring result, and the three-way switching valve is controlled to switch to the venting position.

2. The method for interlocked delayed recovery of oxygen content in converter gas lance according to claim 1, characterized in that: Step S3, controlling the three-way switching valve to remain in the retracted position, specifically includes: By overriding software instructions, after recognizing the initial trigger signal, an internal memory bit, namely the delayed recovery activation flag bit, is set to 1. In the program loop, the original immediate release instruction stream is skipped, and the output point of the digital output module used to drive the solenoid valve of the three-way switching valve is kept in the set state, so that the valve plate of the three-way switching valve is kept in the recovery position.

3. The method for interlocked delayed recovery of oxygen content in converter gas lance according to claim 1, characterized in that: The gas transmission lag time calculation model mentioned in step S3 specifically includes: The physical distance between the gas generation point at the furnace mouth and the sampling point before the three-way switching valve is obtained as the pipeline length. Combined with the real-time flow velocity of the gas in the pipeline obtained by real-time measurement through a vortex flow meter or Pitot tube flow meter, the transmission lag time is calculated.

4. The method for interlocked delayed recovery of oxygen content in converter gas lance according to claim 1, characterized in that: Step S4, which involves real-time monitoring of oxygen levels with the highest priority, also includes: The control system establishes a sliding window data buffer to store oxygen concentration values ​​from the most recent multiple sampling periods. By calculating the first derivative of the oxygen concentration values ​​within the sliding window, it predicts the trend of oxygen content change. When the first derivative exceeds a preset rate of change threshold, it outputs an early warning signal.

5. The method for interlocked delayed recovery of oxygen content in converter gas lance according to claim 1, characterized in that: Step S4 includes dynamic security logic monitoring. This also includes: The instantaneous pressure of the recovery pipeline is monitored synchronously. When the pipeline pressure is detected to be below 0.5 kPa, it is determined that there is a risk of air intake and the protection mechanism is triggered.

6. The method for interlocked delayed recovery of oxygen content in converter gas lance according to claim 1, characterized in that: The security dynamic logic monitoring in step S4 also includes: The carbon monoxide concentration is assessed in real time. When the carbon monoxide concentration is detected to be below the calorific value threshold of 35%, the early termination delay procedure is triggered according to the principle of energy efficiency priority.

7. The method for interlocked delayed recovery of oxygen content in converter gas lance according to claim 1, characterized in that: The execution state switching and safety interlock response described in step S5 specifically include: When the delay timer reaches the preset duration and the oxygen content remains below the safety threshold of 1% and the carbon monoxide concentration remains above the calorific value threshold of 35% throughout the entire delay period, the normal switching process is executed. This involves de-energizing the hydraulic solenoid valve of the three-way switching valve and driving the valve plate to move from the recovery position to the venting position.

8. The method for interlocked delayed recovery of oxygen content in converter gas lance according to claim 1, characterized in that: Step S5 involves executing the state transition and safety interlock response, specifically including: If any of the following abnormal conditions are detected during the delay period: oxygen content reaches or exceeds the safety threshold of 1%, pipeline pressure is below 0.5 kPa, or carbon monoxide concentration is below the calorific value threshold of 35%, the delay timer is immediately interrupted and forced venting mode is entered. Through the dual redundancy mechanism of software-level interrupt handling and hardware-level hard-wired interlocking circuit, the three-way switching valve is controlled to switch to the venting position with the highest priority.

9. The method for interlocked delayed recovery of oxygen content in converter gas lance according to claim 8, characterized in that: The hardwired interlocking circuit at the hardware level specifically includes: An independent hard-wired interlocking circuit is formed by a safety relay. The input side of the safety relay is connected to the alarm relay and the emergency stop button on the control panel of the online laser gas analyzer. The output contact is connected in series in the power supply circuit of the three-way switching valve solenoid valve. When an oxygen content exceeding the limit signal or an emergency stop signal is received, the safety relay directly cuts off the power supply to the solenoid valve, forcing the three-way switching valve to reset to the venting position.

10. A converter gas lance oxygen content interlocking delayed recovery system, characterized in that: The system is used to perform the converter gas lance oxygen content interlocking delayed recovery method according to any one of claims 1 to 9, the system comprising: A signal acquisition module is used to monitor the process status signals at the end of the converter blowing process in real time. The signal acquisition module includes at least: an absolute multi-turn encoder installed at the end of the oxygen lance hoisting system drum shaft to acquire the oxygen lance position signal; a dual-redundant limit switch installed on the oxygen shut-off valve actuator to acquire the oxygen shut-off valve status signal; an online laser gas analysis system installed at the sampling point upstream of the three-way switching valve at the end of the recovery pipeline to acquire the gas composition signal in the recovery pipeline; and a vortex flow meter or Pitot tube flow meter installed in the flue or pipeline to acquire the real-time flow velocity signal in the pipeline. The logic operation module includes a programmable logic controller (PLC). The PLC is configured to: when the oxygen lance position signal exceeds a preset blowing end height threshold and the oxygen shut-off valve status signal changes from open to closed, identify it as the initial trigger signal for termination of recovery, and execute an instruction overwrite operation to suspend the original hard interlock program that triggers the three-way switching valve to the venting position immediately based on the oxygen lance lifting action, and activate the delayed recovery logic; start the delayed recovery logic, acquire the real-time flow velocity signal in the pipeline, calculate the transmission lag time based on the preset pipeline length and set it as a preset duration; during the delayed recovery period, perform dynamic safety logic monitoring and control the blower to maintain the current recovery frequency; The execution control module includes a hydraulic station control unit for driving a three-way switching valve and a solenoid valve drive circuit. The execution control module responds to the instructions of the logic operation module, controls the valve plate of the three-way switching valve to remain in the retracted position for a preset time period, and controls the three-way switching valve to switch to the release position when the preset time period ends or when the safety dynamic logic monitoring triggers the protection condition. The safety protection module includes a hard-wired interlocking circuit composed of safety relays. The input side of the safety relays is connected to the alarm relay of the online laser gas analyzer, and the output side contacts are connected in series in the power supply circuit of the solenoid valve drive circuit. This is used to directly cut off the power supply to the solenoid valve when the logic operation module fails or the oxygen content exceeds the limit.

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