An advanced product analysis switching control system

Abstract

The application discloses an advanced product analysis switching control system. In the application, the continuity and reliability of product gas purity monitoring are effectively ensured through double-instrument mutual backup and pre-starting and post-stopping logical control. When the system is running, two analyzers always maintain one online state, the switching process follows the process of starting the standby instrument first and then closing the original online instrument, and the situation that product gas is not monitored due to switching gap is avoided; in the calibration link, the analyzer to be calibrated is locked as a calibration mode, the product gas path electromagnetic valve is automatically closed, the calibration gas path electromagnetic valve is opened, and meanwhile, the other analyzer is ensured to be in the online state, so that the risk that the calibration gas analysis result is misjudged as product gas purity and unqualified product gas is supplied is completely eliminated, the safety hazard of the traditional system is eliminated from the logical level, the existing PLC system of the air separation device is used as the control core, no complex hardware device is added, and the system construction investment and subsequent maintenance cost are greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of product analysis technology, specifically an advanced product analysis switching control system. Background Technology

[0002] In the production and supply of product gases (such as nitrogen and oxygen) from air separation units, real-time and accurate monitoring of product gas purity is crucial for ensuring product quality standards and safe use by downstream users. Currently, the industry widely employs gas purity analyzers for online detection of air separation product gas purity. However, existing product analysis switching control systems suffer from numerous technical deficiencies in actual operation, making it difficult to meet the demands for high reliability and continuous monitoring. The existing product analysis switching systems have the following problems:

[0003] 1. The analyzer switching logic settings have gradually revealed some shortcomings in ensuring the continuity and reliability of product quality monitoring. For example, the monitoring accuracy of a single analyzer decreases, affecting product purity;

[0004] 2. When switching analyzers, there is a risk of product gas purity not being monitored.

[0005] 3. During the analyzer calibration process, there is a risk that the calibration gas analysis results may be used as the product gas purity, resulting in the supply of impure product gas. Summary of the Invention

[0006] The purpose of this invention is to provide an advanced product analysis and switching control system in order to solve the problems mentioned above.

[0007] The technical solution adopted in this invention is as follows: an advanced product analysis and switching control system, including a core control module, a dual product analysis module, a solenoid valve control module, a dual instrument mutual backup and start-stop logic control module, a status monitoring module, and a human-machine interaction module;

[0008] The internal configuration of the dual instrument mutual backup and start-stop logic control module includes: a status monitoring and trigger judgment submodule, a dual instrument mutual backup switching control submodule, a calibration safety control submodule, and a status synchronization and interaction submodule.

[0009] The analog input module of the core control module is connected to the purity detection signal output terminals of the two gas purity analyzers of the dual-product analysis module, and the digital output module is connected to the control terminal of each solenoid valve of the solenoid valve control module.

[0010] The signal input terminal of the dual-instrument mutual backup and first-start-then-stop logic control module receives data transmitted from the signal output terminals of the current sensor and pressure sensor of the status monitoring module, and the command output terminal is connected to the solenoid valve control terminal of the solenoid valve control module through the digital output module of the core control module.

[0011] The signal output terminal of the current sensor of the status monitoring module is connected to the digital input module of the core control module, and the signal output terminal of the pressure sensor is connected to the analog input module of the core control module.

[0012] The manual operation command output terminal of the human-machine interaction module is connected to the digital input module of the core control module, the status data receiving terminal is connected to the communication port of the core control module via industrial Ethernet, and the alarm information receiving terminal is connected to the digital output module of the core control module.

[0013] In a preferred embodiment, the core control module internally includes the existing PLC system of the air separation unit, a digital input / output module, an analog input module, and preset control subroutines. The existing PLC system of the air separation unit serves as the core control unit, eliminating the need for an additional independent controller. The digital input / output module extends to connect solenoid valves and status sensors, while the analog input module acquires purity detection signals from the analyzer. The preset control subroutines include a dual-instrument backup main program, a status monitoring subroutine, a switching control subroutine, and a calibration control subroutine. These subroutines are integrated into the PLC system, and signal interaction and instruction output between modules are achieved through logic programming.

[0014] In a preferred embodiment, the dual-product analysis module internally includes two identical high-precision gas purity analyzers, parallel sampling points on the main output path of the air separation unit's product gas, and a purity detection signal output interface. The two analyzers are trace oxygen analyzers, with a measurement range covering 0 to 1000 PPM, and are respectively installed at two parallel sampling points on the main output path of the air separation unit's product gas. The purity detection signals from the analyzers are connected to the analog input module of the core control module via the output interface to achieve real-time transmission of the detection data.

[0015] In a preferred embodiment, the solenoid valve control module internally includes a two-position, two-way solenoid valve assembly, a stainless steel valve body, and a connection terminal for a PLC digital output module. Each analyzer is equipped with two two-position, two-way solenoid valves, one for the product gas path and the other for the calibration gas path; the valve body is made of 316L stainless steel; the solenoid valve voltage is matched to the PLC output module at DC24V, and the control terminal is directly connected to the digital output module of the core control module to receive on / off commands from the PLC.

[0016] In a preferred embodiment, the status monitoring and trigger judgment submodule serves as the sensing hub for the dual-instrument backup logic. It collects multi-dimensional data from the status monitoring unit via the PLC's AI / DI module, including the power current signals of the two analyzers, the solenoid valve coil current status, the product gas sampling pressure value, and the purity detection data output by the analyzers. This submodule first preprocesses the raw data: converting the current signal into equipment operating status (e.g., whether the analyzer is powered on, whether the solenoid valve is activated), performing a sliding filter on the pressure signal to eliminate fluctuations, and then extracting the real-time purity value of the analyzer and comparing it with a preset standard value to calculate the error. Subsequently, three judgment threads run in parallel: first, accuracy error judgment, calculating the absolute deviation between the current purity detection value and the target purity; if the deviation exceeds 1 PPM for 5 seconds, it is marked as an accuracy anomaly; second, runtime judgment, accumulating the continuous running time of the online analyzer; if it exceeds 72 hours, it is marked as exceeding the time limit; and third, fault status judgment, detecting analyzer power interruption, solenoid valve jamming, or receiving analyzer fault codes (e.g., sensor malfunction, communication interruption); if any fault exists, it is marked as a fault trigger. Finally, the submodule combines the marking results of the three threads. If any mark is true, a switching trigger signal is generated and sent to the switching control submodule. If multiple marks are satisfied at the same time, the fault trigger is processed first, and an abnormal alarm containing the trigger type and parameters is sent to the status interaction submodule simultaneously.

[0017] The formula for calculating the trigger index is:

[0018] ;

[0019] In the formula:

[0020] T represents the trigger exponent (when T≥T) threshold (Time-triggered switching);

[0021] w E Indicates the precision error weight (default value is 2.0);

[0022] P real This indicates the real-time purity reading from the analyzer (unit: PPM).

[0023] P target This indicates the target purity value of the product gas (unit: PPM).

[0024] w T Indicates runtime weight (default value is 1.5);

[0025] t run Indicates the continuous operating time of the online analyzer (unit: hours);

[0026] t max Indicates the preset maximum operating cycle (unit: hours);

[0027] w F Indicates the fault weight (default value is 5.0);

[0028] F indicates the fault status (0 = no fault, 1 = faulty);

[0029] T threshold This indicates the trigger threshold (default value is 3.0).

[0030] In a preferred embodiment, the input terminal of the dual-instrument backup switching control submodule receives in real time the switching trigger signal transmitted by the status monitoring and trigger judgment submodule, the offline status feedback of the backup analyzer, and hardware status data. Internally, it consists of three layers of logic: trigger response, backup startup, and switching execution. The trigger response layer first determines the priority of the input signal (fault trigger has the highest priority, followed by accuracy anomalies and timeouts), and locks the status identifier of the currently online instrument to prevent repeated triggering. The backup startup layer then sends an "online startup" command to the backup instrument, synchronously controlling the opening of its product gas path solenoid valve, and verifies the effectiveness of the solenoid valve's action through the coil current value returned by the current sensor. Successful opening is determined when the current is ≥80% of the rated value. Simultaneously, the system waits for the analyzer to complete its self-test (receiving the "ready" code from the analyzer) and output stable purity data (fluctuation ≤0.1 PPM for three consecutive sampling values). After confirming that the standby analyzer meets the availability conditions, the switching execution layer sends an "offline" command to the original online analyzer to close its product gas path solenoid valve, updating the status of both analyzers to "standby analyzer online, original online analyzer offline," and generating a record containing the trigger reason and switching time, which is sent to the status synchronization and interaction submodule. If the standby analyzer fails to start (e.g., the solenoid valve is not open, or the self-test fails), the submodule immediately triggers an abnormal alarm and keeps the original online analyzer running to avoid analysis interruption.

[0031] The formula for calculating the availability of standby equipment is:

[0032] ;

[0033] In the formula:

[0034] A represents the availability of the backup device (value range 0~1, ≥0.8 is considered ready);

[0035] α represents the weight of the self-check status (default 0.3);

[0036] R s This indicates the self-test pass rate (1 indicates the self-test passed, 0 indicates the self-test failed).

[0037] β represents the solenoid valve state weight (default 0.4);

[0038] R v This indicates the success rate of the solenoid valve's operation (1 indicates that the solenoid valve is normally open, and 0 indicates that it is not open).

[0039] γ represents the data validity weight (default 0.3);

[0040] R d Indicates data validity (1 indicates purity fluctuation ≤ 0.1 PPM for 3 consecutive samples, 0 indicates fluctuation exceeds the limit).

[0041] In a preferred embodiment, the calibration safety control submodule comprises a six-layer logical structure: an instruction priority determination layer, a calibrator status locking layer, a gas path solenoid valve control layer, a calibration time monitoring layer, an anomaly handling layer, and a status reset layer. The instruction priority determination layer first filters input signals; manual calibration instructions from operators have higher priority than automatic trigger signals. If an invalid instruction is detected simultaneously calibrating two analyzers, it is directly rejected and an error message is returned. Upon receiving a valid calibration instruction, the calibrator status locking layer immediately sends a "calibration lock" flag to the analyzer to be calibrated, preventing it from entering online analysis mode via the PLC program. Simultaneously, it reads the online status of the other analyzer; if the other analyzer is not online, an emergency alarm is triggered and the calibration process is terminated. The gas path solenoid valve control layer then sends an open instruction to the calibration gas path solenoid valve corresponding to the analyzer to be calibrated. The calibration process begins by sending a forced shutdown command to the solenoid valve in the product's pneumatic circuit. The effectiveness of the solenoid valve's action is verified by the coil current value returned by the current sensor (a successful action is defined as a coil current ≥ 90% of the rated value). The calibration time monitoring layer activates a high-precision timer to calculate the calibration duration in real time. When the time exceeds a preset threshold (e.g., 30 minutes), a timeout alarm signal is generated, and a confirmation request to the operator is sent asking whether to continue calibration. The exception handling layer receives the timeout alarm or solenoid valve failure signal. If the operator confirms to continue, the timer is reset (repeated every 30 minutes). If termination is confirmed, the calibration solenoid valve is immediately closed, and the calibrated instrument is unlocked. Upon receiving the calibration completion command, the status reset layer closes the calibration solenoid valve, unlocks the calibrated instrument, sends an "online preparation" command, and synchronizes the calibration completion status to the status synchronization and interaction submodule.

[0042] The formula for calculating the calibration safety factor is as follows:

[0043] ;

[0044] In the formula:

[0045] S represents the calibration safety factor (ranging from 0 to 1, with a value ≥ 0.8 indicating a safe calibration process).

[0046] 'a' represents the weight of the locked state of the instrument to be calibrated (default 0.4).

[0047] L indicates the locked status of the instrument to be calibrated (1 indicates locked, 0 indicates unlocked).

[0048] b represents the online instrument status weight (default 0.4);

[0049] 0 indicates that another analyzer is online (1 indicates online, 0 indicates offline);

[0050] c represents the calibration time factor weight (default 0.2);

[0051] T represents the current calibration duration (in minutes);

[0052] t0 represents the calibration time threshold (default 30 minutes).

[0053] This formula integrates three core safety dimensions: the locked state of the instrument to be calibrated, the online status of the instrument, and the reasonableness of the calibration time. It quantitatively assesses the safety of the calibration process and ensures that continuous calibration is only allowed when the instrument to be calibrated is completely locked, the other instrument is online normally, and the calibration time has not exceeded. This effectively avoids the risk of unqualified gas supply.

[0054] In a preferred embodiment, the state synchronization and interaction submodule consists of four logical layers: a state identifier management layer, a data synchronization layer, a manual command priority processing layer, and an alarm information integration layer. The state identifier management layer maintains the dynamic state matrix (online / offline / calibration / fault) of the two analyzers, updating the state values ​​every 500ms and synchronizing them to the PLC global variable area. The data synchronization layer packages real-time purity data, solenoid valve action status, calibration progress, and other information from the analyzers according to the MODBUS protocol and sends it to the central control SCADA system via industrial Ethernet, while simultaneously receiving feedback signals from the central control system to verify the validity of the data transmission. The manual command priority processing layer processes the received data... Manual commands undergo validity checks (e.g., prohibiting simultaneous calibration of two analyzers) and are prioritized according to "emergency stop > manual calibration > manual switching." If a manual command conflicts with automatic logic (e.g., manually shutting down an online instrument), execution is rejected and the reason is reported. The alarm information integration layer categorizes abnormal signals sent by each submodule (e.g., switching failure, calibration timeout) according to severity (emergency / warning / prompt), generates standardized alarm logs (including timestamps, triggering modules, and parameter values), and pushes them to the central control interface pop-up for display. The output forwards valid manual commands to each submodule, sends real-time status data and alarm logs to the central control, and simultaneously feeds back data synchronization results to the status monitoring submodule.

[0055] The formula for calculating the data synchronization effectiveness coefficient is as follows:

[0056] ;

[0057] In the formula:

[0058] S represents the data synchronization validity coefficient (the value ranges from 0 to 1, and ≥0.9 is considered to be normal synchronization).

[0059] w F Indicates the update frequency weight (default 0.4);

[0060] F represents the state update frequency (the number of updates per second, such as 2 times / second, then F=2).

[0061] w I Indicates the data integrity weight (default 0.3);

[0062] 1 indicates data integrity (1 indicates all fields are complete, 0 indicates missing key fields);

[0063] w D Indicates the delay factor weight (default 0.3);

[0064] T represents the data transmission delay (in milliseconds);

[0065] t0 represents the maximum allowed delay (default 100ms).

[0066] In a preferred embodiment, the status monitoring module internally includes a current sensor, a pressure sensor, an analog input module interface, and a digital input module interface. The current sensor is installed at the analyzer power supply terminal and the solenoid valve coil terminal, respectively; the pressure sensor is installed at the product gas sampling point; the signal output terminals of all sensors are connected to the analog input module and digital input module of the core control module through interfaces to realize real-time acquisition of status data.

[0067] In a preferred embodiment, the human-machine interface module internally includes an analyzer status display area, a manual operation area, an alarm recording area, and a manual intervention command output interface. The analyzer status display area shows the online and offline calibration status and real-time purity values ​​of the two analyzers; the manual operation area includes a manual switching button and a calibration start button; the alarm recording area records information related to switching anomalies and calibration failures; and the manual intervention commands are transmitted to the core control module through the output interface, with command priority lower than that of the automatic logic.

[0068] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0069] 1. In this invention, the continuity and reliability of product gas purity monitoring are effectively ensured through dual-instrument backup and start-then-stop logic control. During system operation, one of the two analyzers remains online at all times. The switching process follows the procedure of starting the backup analyzer first and then shutting down the original online analyzer, avoiding situations where product gas purity monitoring is not available during the switching interval. During the calibration phase, the analyzer to be calibrated is locked into calibration mode, its product gas path solenoid valve automatically closes, and its calibration gas path solenoid valve opens, while ensuring that the other analyzer remains online. This completely eliminates the risk of misinterpreting calibration gas analysis results as product gas purity, leading to the supply of unqualified product gas, and logically eliminates the safety hazards of traditional systems.

[0070] 2. In this invention, the existing PLC system of the air separation unit is used as the control core, without adding complex hardware equipment, which significantly reduces the investment in system construction and subsequent maintenance costs. The PLC program integrates core logic such as status monitoring, switching control, and calibration control. Operators can monitor the analyzer status in real time and make manual interventions through the central control interface. The intelligent control process reduces the possibility of human error. At the same time, system maintenance only requires routine configuration adjustments to the PLC program, without the need for professional personnel to repair complex hardware. The overall maintenance process is simple and efficient, suitable for the long-term stable operation requirements of the air separation unit. Attached Figure Description

[0071] Figure 1 This is an overall system block diagram of the present invention;

[0072] Figure 2 This is a system block diagram of the dual-instrument mutual backup and start-up-stop logic control module in this invention;

[0073] Figure 3 This is the sample gas diagram of the analyzer in this invention.

[0074] The diagram is labeled as follows: 1 - Core control module, 2 - Dual product analysis module, 3 - Solenoid valve control module, 4 - Dual instrument backup and start-stop logic control module, 5 - Status monitoring module, 6 - Human-machine interaction module, 7 - Status monitoring and trigger judgment submodule, 8 - Dual instrument backup switching control submodule, 9 - Calibration safety control submodule, 10 - Status synchronization and interaction submodule. Detailed Implementation

[0075] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0076] Example:

[0077] Reference Figure 1-3An advanced product analysis and switching control system includes a core control module 1, a dual product analysis module 2, a solenoid valve control module 3, a dual instrument backup and start-stop logic control module 4, a status monitoring module 5, and a human-machine interaction module 6.

[0078] The internal configuration of the dual instrument backup and start-stop logic control module 4 includes: status monitoring and trigger judgment submodule 7, dual instrument backup switching control submodule 8, calibration safety control submodule 9, and status synchronization and interaction submodule 10.

[0079] The analog input module of the core control module 1 is connected to the purity detection signal output terminals of the two gas purity analyzers in the dual-product analysis module 2, and the digital output module is connected to the control terminal of each solenoid valve in the solenoid valve control module 3.

[0080] The signal input terminal of the dual-instrument mutual backup and first-start-after-stop logic control module 4 receives data transmitted from the signal output terminals of the current sensor and pressure sensor of the status monitoring module 5, and the command output terminal is connected to the solenoid valve control terminal of the solenoid valve control module 3 through the digital output module of the core control module 1.

[0081] The signal output terminal of the current sensor of the status monitoring module 5 is connected to the digital input module of the core control module 1, and the signal output terminal of the pressure sensor is connected to the analog input module of the core control module 1.

[0082] The manual operation command output terminal of the human-machine interaction module 6 is connected to the digital input module of the core control module 1, the status data receiving terminal is connected to the communication port of the core control module 1 via industrial Ethernet, and the alarm information receiving terminal is connected to the digital output module of the core control module 1.

[0083] The core control module 1 internally includes the existing PLC system of the air separation unit, digital input / output modules, analog input modules, and preset control subroutines. The existing PLC system serves as the core control unit, eliminating the need for an additional independent controller. The digital input / output modules are used to connect solenoid valves and status sensors, while the analog input modules acquire purity detection signals from the analyzer. The preset control subroutines include a dual-instrument backup main program, a status monitoring subroutine, a switching control subroutine, and a calibration control subroutine. These subroutines are integrated into the PLC system, and signal interaction and command output between modules are achieved through logic programming.

[0084] The dual-product analysis module 2 is internally equipped with two identical high-precision gas purity analyzers, parallel sampling points on the main output path of the air separation unit's product gas, and a purity detection signal output interface. The two analyzers are trace oxygen analyzers, with a measurement range covering 0 to 1000 PPM, and are installed at two parallel sampling points on the main output path of the air separation unit's product gas. The purity detection signals from the analyzers are connected to the analog input module of the core control module via the output interface, enabling real-time transmission of the detection data.

[0085] The solenoid valve control module 3 internally houses a two-position, two-way solenoid valve assembly, a stainless steel valve body, and a connection terminal for the PLC digital output module. Each analyzer is equipped with two two-position, two-way solenoid valves, one for the product gas path and the other for the calibration gas path. The valve body is made of 316L stainless steel. The solenoid valve voltage is matched to the PLC output module at DC24V, and the control terminal is directly connected to the digital output module of the core control module to receive on / off commands from the PLC.

[0086] The status monitoring and trigger judgment submodule 7 serves as the sensing hub for the dual-instrument backup logic. It collects multi-dimensional data from the status monitoring unit via the PLC's AI / DI module, including the power current signals of the two analyzers, the solenoid valve coil current status, the product gas sampling pressure value, and the purity detection data output by the analyzers. This submodule first preprocesses the raw data: converting the current signal into equipment operating status (e.g., whether the analyzer is powered on, whether the solenoid valve is activated), performing a sliding filter on the pressure signal to eliminate fluctuations, and then extracting the real-time purity value of the analyzer and comparing it with the preset standard value to calculate the error. Subsequently, three judgment threads run in parallel: first, accuracy error judgment, calculating the absolute deviation between the current purity detection value and the target purity; if the deviation continues to exceed 1 PPM for 5 seconds, it is marked as an accuracy anomaly; second, runtime judgment, accumulating the continuous running time of the online analyzer; if it exceeds 72 hours, it is marked as exceeding the time limit; third, fault status judgment, detecting analyzer power interruption, solenoid valve jamming, or receiving analyzer fault codes (e.g., sensor malfunction, communication interruption); if any fault exists, it is marked as a fault trigger. Finally, the submodule combines the marking results of the three threads. If any mark is true, a switching trigger signal is generated and sent to the switching control submodule. If multiple marks are satisfied at the same time, the fault trigger is processed first, and an abnormal alarm containing the trigger type and parameters is sent to the status interaction submodule simultaneously.

[0087] The formula for calculating the trigger index is:

[0088] ;

[0089] In the formula:

[0090] T represents the trigger exponent (when T≥T) threshold (Time-triggered switching);

[0091] w E Indicates the precision error weight (default value is 2.0);

[0092] P real This indicates the real-time purity reading from the analyzer (unit: PPM).

[0093] P target This indicates the target purity value of the product gas (unit: PPM).

[0094] w T Indicates runtime weight (default value is 1.5);

[0095] t run Indicates the continuous operating time of the online analyzer (unit: hours);

[0096] t max Indicates the preset maximum operating cycle (unit: hours);

[0097] w F Indicates the fault weight (default value is 5.0);

[0098] F indicates the fault status (0 = no fault, 1 = faulty);

[0099] T threshold Indicates the trigger threshold (default value is 3.0);

[0100] The input terminal of the dual-instrument backup switching control submodule 8 receives in real time the switching trigger signal transmitted by the status monitoring and trigger judgment submodule, the offline status feedback of the backup analyzer, and hardware status data. Internally, it consists of three layers of logic: trigger response, backup start, and switching execution. The trigger response layer first determines the priority of the input signal (fault trigger has the highest priority, followed by accuracy abnormality and running timeout), and locks the status flag of the currently online instrument to prevent repeated triggering. The backup start layer then sends an "online start" command to the backup instrument, synchronously controls the opening of its product gas circuit solenoid valve, and verifies the effectiveness of the solenoid valve action by the coil current value returned by the current sensor (current ≥ rated value). (80% chance of successful opening) while waiting for the analyzer to complete its self-test (receiving the "ready" code from the analyzer) and output stable purity data (fluctuation of ≤0.1PPM for 3 consecutive sampling values); After confirming that the standby analyzer meets the availability conditions, the switching execution layer sends an "offline" command to the original online analyzer to close its product gas path solenoid valve, updates the status of both analyzers to "standby analyzer online, original online analyzer offline", and generates a record containing the trigger reason and switching time, which is sent to the status synchronization and interaction submodule; If the standby analyzer fails to start (e.g., the solenoid valve is not open, or the self-test fails), the submodule immediately triggers an abnormal alarm and keeps the original online analyzer running to avoid analysis interruption.

[0101] The formula for calculating the availability of standby equipment is:

[0102] ;

[0103] In the formula:

[0104] A represents the availability of the backup device (value range 0~1, ≥0.8 is considered ready);

[0105] α represents the weight of the self-check status (default 0.3);

[0106] R s This indicates the self-test pass rate (1 indicates the self-test passed, 0 indicates the self-test failed).

[0107] β represents the solenoid valve state weight (default 0.4);

[0108] R v This indicates the success rate of the solenoid valve's operation (1 indicates that the solenoid valve is normally open, and 0 indicates that it is not open).

[0109] γ represents the data validity weight (default 0.3);

[0110] R d Indicates data validity (1 indicates purity fluctuation ≤ 0.1 PPM for 3 consecutive samples, 0 indicates fluctuation exceeds the limit).

[0111] The calibration safety control submodule 9 consists of a six-layer logical structure: an instruction priority determination layer, a calibrator status locking layer, a gas path solenoid valve control layer, a calibration time monitoring layer, an anomaly handling layer, and a status reset layer. The instruction priority determination layer first filters input signals; manual calibration instructions from operators have higher priority than automatic trigger signals. If an invalid instruction is detected calibrating two analyzers simultaneously, it is directly rejected and an error message is provided. Upon receiving a valid calibration instruction, the calibrator status locking layer immediately sends a "calibration lock" flag to the analyzer to be calibrated, preventing it from entering online analysis mode via the PLC program. Simultaneously, it reads the online status of the other analyzer; if the other analyzer is not online, an emergency alarm is triggered, and the calibration process is terminated. The gas path solenoid valve control layer then sends an open instruction to the corresponding calibration gas path solenoid valve of the analyzer to be calibrated, simultaneously supplying it with product gas. The solenoid valve sends a forced shutdown command, and the validity of the solenoid valve action is verified by the coil current value returned by the current sensor (the action is considered successful if the coil current is ≥90% of the rated value). The calibration time monitoring layer starts a high-precision timer to calculate the calibration duration in real time. When the time exceeds a preset threshold (e.g., 30 minutes), an overtime alarm signal is generated, and a confirmation request for "continue calibration" is sent to the operator. The exception handling layer receives the overtime alarm or solenoid valve action failure signal. If the operator confirms to continue, the timer is reset (repeated every 30 minutes). If the operator confirms to terminate, the calibration gas solenoid valve is immediately closed and the instrument to be calibrated is unlocked. After receiving the calibration completion command, the status reset layer closes the calibration gas solenoid valve, unlocks the instrument to be calibrated, sends an "online preparation" command to it, and synchronizes the calibration completion status to the status synchronization and interaction submodule.

[0112] The formula for calculating the calibration safety factor is as follows:

[0113] ;

[0114] In the formula:

[0115] S represents the calibration safety factor (ranging from 0 to 1, with a value ≥ 0.8 indicating a safe calibration process).

[0116] 'a' represents the weight of the locked state of the instrument to be calibrated (default 0.4).

[0117] L indicates the locked status of the instrument to be calibrated (1 indicates locked, 0 indicates unlocked).

[0118] b represents the online instrument status weight (default 0.4);

[0119] 0 indicates that another analyzer is online (1 indicates online, 0 indicates offline);

[0120] c represents the calibration time factor weight (default 0.2);

[0121] T represents the current calibration duration (in minutes);

[0122] t0 represents the calibration time threshold (default 30 minutes).

[0123] This formula integrates three core safety dimensions: the locked state of the instrument to be calibrated, the online status of the instrument, and the reasonableness of the calibration time. It quantitatively assesses the safety of the calibration process and ensures that continuous calibration is only allowed when the instrument to be calibrated is completely locked, the other instrument is online normally, and the calibration time has not exceeded. This effectively avoids the risk of unqualified gas supply.

[0124] The status synchronization and interaction submodule 10 consists of four logical layers: a status identification management layer, a data synchronization layer, a manual command priority processing layer, and an alarm information integration layer. The status identification management layer maintains the dynamic status matrix (online / offline / calibration / fault) of the two analyzers, updating the status values ​​every 500ms and synchronizing them to the PLC's global variable area. The data synchronization layer packages real-time purity data, solenoid valve action status, calibration progress, and other information from the analyzers according to the MODBUS protocol and sends it to the central control SCADA system via industrial Ethernet, while simultaneously receiving feedback signals from the central control system to verify the validity of the data transmission. The manual command priority processing layer processes the received manual commands. The system performs validity checks (e.g., prohibiting simultaneous calibration of two analyzers) and prioritizes them according to "emergency stop > manual calibration > manual switching." If a manual command conflicts with automatic logic (e.g., manually shutting down an online analyzer), execution is rejected and the reason is reported. The alarm information integration layer categorizes abnormal signals sent by each submodule (e.g., switching failure, calibration timeout) according to severity (emergency / warning / prompt), generates standardized alarm logs (including timestamps, triggering modules, and parameter values), and pushes them to the central control interface for pop-up display. The output forwards valid manual commands to each submodule, sends real-time status data and alarm logs to the central control, and simultaneously feeds back data synchronization results to the status monitoring submodule.

[0125] The formula for calculating the data synchronization effectiveness coefficient is as follows:

[0126] ;

[0127] In the formula:

[0128] S represents the data synchronization validity coefficient (the value ranges from 0 to 1, and ≥0.9 is considered to be normal synchronization).

[0129] w F Indicates the update frequency weight (default 0.4);

[0130] F represents the state update frequency (the number of updates per second, such as 2 times / second, then F=2).

[0131] w IIndicates the data integrity weight (default 0.3);

[0132] 1 indicates data integrity (1 indicates all fields are complete, 0 indicates missing key fields);

[0133] w D Indicates the delay factor weight (default 0.3);

[0134] T represents the data transmission delay (in milliseconds);

[0135] t0 represents the maximum allowable delay (default 100ms);

[0136] The status monitoring module 5 is internally equipped with a current sensor, a pressure sensor, an analog input module interface, and a digital input module interface. The current sensors are installed at the analyzer power supply terminal and the solenoid valve coil terminal, respectively; the pressure sensor is installed at the product gas sampling point; the signal output terminals of all sensors are connected to the analog input module and digital input module of the core control module through interfaces to realize real-time acquisition of status data.

[0137] The human-machine interface module 6 internally includes an analyzer status display area, a manual operation area, an alarm recording area, and a manual intervention command output interface. The analyzer status display area shows the online and offline calibration status and real-time purity values ​​of the two analyzers; the manual operation area includes a manual switching button and a calibration start button; the alarm recording area records information related to switching anomalies and calibration failures; manual intervention commands are transmitted to the core control module through the output interface, with command priority lower than that of automatic logic.

[0138] From the above, we can conclude that:

[0139] In this invention, the continuity and reliability of product gas purity monitoring are effectively ensured through dual-instrument backup and start-before-stop logic control. During system operation, one of the two analyzers remains online at all times. The switching process follows a procedure of first starting the backup analyzer and then shutting down the original online analyzer, avoiding situations where product gas purity monitoring is unavailable during switching intervals. During calibration, the analyzer to be calibrated is locked into calibration mode, its product gas path solenoid valve automatically closes, and its calibration gas path solenoid valve opens, while simultaneously ensuring the other analyzer remains online. This completely eliminates the risk of misinterpreting calibration gas analysis results as product gas purity, leading to the supply of substandard product gas, and logically eliminates the safety hazards of traditional systems.

[0140] In this invention, the existing PLC system of the air separation unit is used as the control core, without adding complex hardware equipment, which significantly reduces the investment in system construction and subsequent maintenance costs. The PLC program integrates core logic such as status monitoring, switching control, and calibration control. Operators can monitor the analyzer status in real time and perform manual intervention through the central control interface. The intelligent control process reduces the possibility of human error. At the same time, system maintenance only requires routine configuration adjustments to the PLC program, without the need for professional personnel to repair complex hardware. The overall maintenance process is simple and efficient, suitable for the long-term stable operation requirements of the air separation unit.

[0141] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0142] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An advanced product analysis and switching control system, characterized in that: It includes a core control module (1), a dual-product analysis module (2), a solenoid valve control module (3), a dual-instrument mutual backup and start-stop logic control module (4), a status monitoring module (5), and a human-machine interaction module (6). The internal configuration of the dual instrument backup and start-stop logic control module (4) includes: a status monitoring and trigger judgment submodule (7), a dual instrument backup switching control submodule (8), a calibration safety control submodule (9), and a status synchronization and interaction submodule (10). The analog input module of the core control module (1) is connected to the purity detection signal output terminal of the two gas purity analyzers of the dual product analysis module (2), and the digital output module is connected to the control terminal of each solenoid valve of the solenoid valve control module (3). The signal input terminal of the dual instrument backup and first start then stop logic control module (4) receives data transmitted from the signal output terminals of the current sensor and pressure sensor of the status monitoring module (5), and the command output terminal is connected to the solenoid valve control terminal of the solenoid valve control module (3) through the digital output module of the core control module (1). The signal output terminal of the current sensor of the status monitoring module (5) is connected to the digital input module of the core control module (1), and the signal output terminal of the pressure sensor is connected to the analog input module of the core control module (1). The manual operation instruction output terminal of the human-machine interaction module (6) is connected to the digital input module of the core control module (1), the status data receiving terminal is connected to the communication port of the core control module (1) through industrial Ethernet, and the alarm information receiving terminal is connected to the digital output module of the core control module (1).

2. The advanced product analysis and switching control system as described in claim 1, characterized in that: The core control module (1) is internally equipped with the existing PLC system of the air separation unit, digital input / output module, analog input module and preset control subroutine; the existing PLC system of the air separation unit serves as the core control unit, and no additional independent controller is required; the digital input / output module is extended to connect solenoid valves and status sensors, and the analog input module collects the purity detection signal of the analyzer; The preset control subroutines include a dual-instrument backup main program, a status monitoring subroutine, a switching control subroutine, and a calibration control subroutine. The subroutines are integrated into the PLC system, and signal interaction and instruction output between modules are realized through logic programming.

3. The advanced product analysis and switching control system as described in claim 1, characterized in that: The dual-product analysis module (2) is equipped with two high-precision gas purity analyzers of the same model, a parallel sampling point on the main output path of the air separation unit's product gas, and a purity detection signal output interface. The two analyzers are trace oxygen analyzers with a measurement range covering 0 to 1000 PPM, and are installed at two parallel sampling points on the main output path of the air separation unit's product gas. The purity detection signal of the analyzer is connected to the analog input module of the core control module through the output interface to realize the real-time transmission of detection data.

4. The advanced product analysis and switching control system as described in claim 1, characterized in that: The solenoid valve control module (3) is internally equipped with a two-position two-way solenoid valve group, a stainless steel valve body, and a PLC digital output module connection terminal; each analyzer is equipped with two two-position two-way solenoid valves, which are used for the product gas path and the calibration gas path, respectively; the valve body is made of 316L stainless steel; the voltage of the solenoid valve is matched with the PLC output module as DC24V, and the control terminal is directly connected to the digital output module of the core control module to receive the on / off command from the PLC.

5. The advanced product analysis and switching control system as described in claim 1, characterized in that: The status monitoring and trigger judgment submodule (7) is the sensing center of the dual instrument backup logic. It collects multi-dimensional data of the status monitoring unit through the AI / DI module of the PLC, including the power current signal of the two analyzers, the current status of the solenoid valve coil, the sampling pressure value of the product gas path, and the purity detection data output by the analyzer. The submodule first preprocesses the raw data: converts the current signal into the equipment operating status, performs sliding filtering on the pressure signal to eliminate fluctuations, and then extracts the real-time purity value of the analyzer and compares it with the preset standard value to calculate the error. Then, three judgment threads are run in parallel: one is the accuracy error judgment, which calculates the absolute deviation between the current purity detection value and the target purity. If the deviation continues to exceed 1PPM for 5 seconds, the accuracy is marked as abnormal. Second, runtime judgment: the cumulative continuous running time of the online analyzer is used, and if it exceeds 72 hours, the runtime is marked as exceeding the limit. Third, fault status judgment: the analyzer power interruption or solenoid valve jamming is detected by the current sensor, or the analyzer's own fault code is received. If any fault exists, the fault is marked as triggered. Finally, the submodule integrates the marking results of the three threads. If any mark is true, a switching trigger signal is generated and sent to the switching control submodule. If multiple marks are satisfied at the same time, the fault trigger is processed first, and an abnormal alarm containing the trigger type and parameters is sent to the status interaction submodule at the same time. The formula for calculating the trigger index is: ； In the formula: T represents the trigger index; w E Indicates the precision error weight; P real This indicates the real-time purity reading from the analyzer. P target This indicates the target purity value of the product gas; w T Indicates runtime weight; t run Indicates the continuous operating time of the online analyzer; t max Indicates the preset maximum running cycle; w F Indicates fault weight; F indicates a fault condition; T threshold This indicates the trigger threshold.

6. The advanced product analysis and switching control system as described in claim 1, characterized in that: The dual-instrument mutual backup switching control submodule (8) consists of three layers of logic: trigger response, backup start-up, and switching execution. The formula for calculating the availability of standby equipment is: ； In the formula: A indicates the availability of backup equipment; α represents the weight of the self-check status; R s Indicates the self-test pass rate; β represents the solenoid valve state weight; R v This indicates the success rate of the solenoid valve's operation. γ represents the data validity weight; R d This indicates the validity of the data.

7. The advanced product analysis and switching control system as described in claim 1, characterized in that: The calibration safety control submodule (9) consists of a six-layer logical structure: instruction priority determination layer, instrument status locking layer, gas path solenoid valve control layer, calibration time monitoring layer, abnormality handling layer, and status reset layer. The formula for calculating the calibration safety factor is as follows: ； In the formula: S represents the calibration safety factor; 'a' represents the weight of the locked state of the instrument to be calibrated; L indicates that the calibrator is locked; b represents the online instrument status weight; O indicates that another analyzer is online; c represents the calibration time factor weight; T represents the current calibration duration; t0 represents the calibration time threshold.

8. The advanced product analysis and switching control system as described in claim 1, characterized in that: The state synchronization and interaction submodule (10) consists of four logical layers: state identifier management layer, data synchronization layer, manual command priority processing layer, and alarm information integration layer. The formula for calculating the data synchronization effectiveness coefficient of the state synchronization and interaction submodule (10) is as follows: ； In the formula: S represents the data synchronization validity coefficient; w F Indicates the update frequency weight; F represents the state update frequency; w I Indicates data integrity weight; I indicates data integrity; w D Indicates the weight of the delay factor; T represents the data transmission delay; t0 represents the maximum allowable delay.

9. The advanced product analysis and switching control system as described in claim 1, characterized in that: The status monitoring module (5) is internally equipped with a current sensor, a pressure sensor, an analog input module interface, and a digital input module interface.

10. An advanced product analysis and switching control system as described in claim 1, characterized in that: The human-computer interaction module (6) is internally equipped with an analyzer status display area, a manual operation area, an alarm recording area, and a manual intervention command output interface.

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