An online control system for the preparation of inorganic ultrafiltration membranes

Abstract

This invention relates to the field of general control or regulation system technology, and discloses an online control system for inorganic ultrafiltration membrane preparation, including: an atmosphere flow control unit, a gas analysis unit, and a control unit. The control unit has a control mode and a characterization mode. In the control mode, the control unit calculates the process variable of the target release rate to track the set value of the ideal rate curve. In the characterization mode, the control unit records the batch characteristic rate curve, extracts key characteristic parameters and compares them with the formulation benchmark window. When the comparison is successful, the set value is updated based on the batch characteristic rate curve. This invention enables the control system to get rid of its dependence on indirect temperature proxy and realize direct management of the actual rate inside the membrane preform. With its inherent logical verification and set value adaptive capability, it avoids the risk of raw material batch fluctuations and misfeeding.

Description

Technical Field

[0001] This invention relates to an online control system for the preparation of inorganic ultrafiltration membranes, belonging to the field of general control or regulation system technology. Background Technology

[0002] Currently, in the preparation process of inorganic ultrafiltration membranes, high-temperature sintering is the core process that determines the final membrane pore size and strength. In this process, the organic binders and pore-forming agents in the membrane preform must decompose, burn, and be discharged at a specific rate, while the ceramic grains undergo grain boundary diffusion and growth. In existing technologies, the control system for this sintering process commonly employs temperature process control. The control system uses the furnace temperature as the process variable to strictly track the preset temperature setpoint curve. This control method operates under ideal, undisturbed conditions and is currently the mainstream technology practice commonly used in the industry. However, under the real-world conditions of large-scale production, the above control method has inherent limitations: control... The furnace temperature anchored by the system is merely an indirect and delayed environmental proxy, not the true process target that determines membrane quality. The true process target is the rate of organic matter decomposition inside the membrane preform. This rate depends not only on the furnace temperature but is also directly affected by a large number of unmeasured, high-frequency disturbances, such as raw material batch fluctuations, membrane preform coating thickness, and furnace atmosphere flow. When the control system maintains a fixed furnace temperature curve, the true process rate will deviate significantly from the ideal state in the face of the above disturbances, such as a high binder content in a certain batch of membrane preforms. For example, decomposition may be too fast, leading to membrane cracking, or decomposition may be too slow, leading to residual carbon. The control system cannot detect the rate deviation and lacks corresponding adjustment measures.

[0003] The open-loop control approach relying on a fixed temperature program is not only the mainstream practice in current production lines but also deeply ingrained in many inorganic membrane preparation method patents. For example, Chinese invention patent CN1216675C discloses a method for preparing an inorganic ultrafiltration membrane. This approach couples wet chemical methods with particle sintering methods. However, in the critical sintering membrane formation process, the technical approach controls the membrane pore size by adjusting the sintering temperature and heating rate, specifically limiting the gradual heating rate during the calcination process to 1~3℃ / minute. This method is essentially still based on a preset fixed open-loop temperature program, focusing on the environmental parameter of furnace temperature rather than the actual process target of the decomposition rate of organic matter inside the membrane preform. Like existing mainstream technologies, this method cannot perceive or compensate for deviations in the actual rate caused by factors such as raw material batch fluctuations and coating thickness, and also faces the risk of membrane cracking or residual carbon.

[0004] Therefore, the technical problem to be solved by this invention is how to get rid of the dependence on furnace temperature as an indirect proxy and instead obtain or construct a new process variable that can truly and in real time characterize the rate of physicochemical changes inside the membrane preform. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: An online control system for the preparation of inorganic ultrafiltration membranes, comprising an atmosphere flow control unit, a gas analysis unit, and a control unit:

[0006] The control unit includes a setpoint adaptive module and is electrically connected to the atmosphere flow control unit and the gas analysis unit.

[0007] The atmosphere flow control unit is used to control the air intake of the sintering furnace according to the set air intake flow rate;

[0008] The gas analysis unit is used to measure the real-time concentration of target emissions in the exhaust gas from the sintering furnace;

[0009] The control unit is used to calculate the process variable of the mass rate of the target release substance in real time based on the real-time concentration of the target release substance and the set flow rate of the inlet air in control mode, obtain the set value of the ideal rate curve, and generate a control output signal to adjust the actuator of the sintering furnace based on the error between the process variable of the mass rate of the target release substance and the set value of the ideal rate curve.

[0010] The setpoint adaptive module is used to control the actuator to execute a preset standard open-loop temperature program in characterization mode, and simultaneously record the batch characteristic rate curve using the calculation results of the process variable of the target release mass rate. The setpoint adaptive module is also used to extract key characteristic parameters from the batch characteristic rate curve before generating the setpoint of the ideal rate curve; compare the key characteristic parameters with a preset formulation baseline window; and generate an updated setpoint of the ideal rate curve based on the batch characteristic rate curve when the key characteristic parameters are within the formulation baseline window.

[0011] Preferably, the control unit is used in control mode to transmit data via PV. Rate =C out ×F in The calculation method calculates the process variable of the target release rate; where PV Rate C is the process variable representing the rate at which the target mass is released. out For the real-time concentration of the target release, F in Set the intake airflow.

[0012] Preferably, the actuator is a heating power regulator for a sintering furnace.

[0013] Preferably, the key characteristic parameters include the time integral value of the batch characteristic rate curve and the peak occurrence time of the batch characteristic rate curve.

[0014] Preferably, the setpoint adaptive module is also used to generate an alarm signal to terminate the standard open-loop temperature program when the key characteristic parameter is outside the formulation baseline window.

[0015] Preferably, the system further includes: an oxygen analysis unit for measuring the oxygen concentration in the exhaust gas of the sintering furnace, wherein the control unit is also used to obtain a preset reference oxygen concentration; calculate a dilution calibration factor based on the exhaust oxygen concentration, the preset reference oxygen concentration and the known stoichiometric relationship of organic matter combustion consumption; and correct the calculation of the process variable of the target release rate based on the dilution calibration factor.

[0016] Preferably, the control unit is used to: calculate the true concentration based on the real-time concentration of the target release agent and the dilution calibration factor; and calculate the process variable of the corrected mass rate of the target release agent based on the true concentration and the inlet set flow rate.

[0017] Preferably, the system further includes: an intake analysis unit for measuring the concentration of the target release product in the intake air before the intake air set flow rate enters the sintering furnace; wherein, the control unit is also used to compensate for the calculation of the process variable of the target release product mass rate based on the intake air target release product concentration.

[0018] Preferably, the control unit is used to: calculate the difference between the real-time concentration of the target release substance and the concentration of the target release substance in the intake air; and calculate the process variable of the compensated target release substance mass rate based on the difference and the intake air set flow rate.

[0019] Preferably, the control unit is also used to monitor the process variable of the target release mass rate; compare the process variable of the target release mass rate with a preset process endpoint reference threshold; and trigger a process switching signal when the process variable of the target release mass rate is lower than the process endpoint reference threshold and the current running time is greater than the preset minimum process time.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. The control loop constructed by the control unit of this invention no longer tracks the indirect and lagging furnace temperature at its core logic. Instead, it utilizes the signals from the atmosphere flow control unit and the gas analysis unit to decouple and construct the real process variable that directly characterizes the decomposition rate of organic matter inside the membrane preform in real time through a specific algorithm of the control unit. The control unit adjusts the heating actuator to ensure that the real rate process variable strictly tracks the preset ideal rate curve. This enables the control system to directly manage the core process target. When faced with operating disturbances that traditional temperature control systems cannot detect, such as raw material batch fluctuations or uneven coating thickness, this system automatically adjusts the heating strategy in real time. This forces the internal micro-evolution process of the membrane preform in different initial states to be constrained to the same ideal process rate path, ensuring a high degree of consistency in the performance of the final product from the control mechanism.

[0022] 2. The control system of this invention incorporates an intake air analysis unit and an oxygen analysis unit, employing a dual correction mechanism of differential compensation and dilution calibration for process variables. The control unit utilizes the intake target release concentration measured by the intake air analysis unit to differentially reconstruct the core rate calculation logic, dynamically eliminating baseline drift interference caused by fluctuations in the factory's ambient air. The control unit uses the exhaust oxygen concentration measured by the oxygen analysis unit, combined with the reference oxygen concentration, to calculate the dilution calibration factor in real time, correcting the dilution distortion of the real-time concentration caused by air leakage due to the non-absolute sealing of the sintering furnace. This collaborative calculation based on orthogonal bypass information and differential mass balance ensures the authenticity and purity of the core process variables upon which the control unit relies, enabling the control logic to remain accurate and reliable in real, non-ideal industrial environments, such as air leakage or ambient air pollution.

[0023] 3. The control unit of this invention integrates a setpoint adaptive module. Before processing a new batch of preforms, this module automatically switches to characterization mode, controls the actuator to execute the standard open-loop temperature program, and reuses the rate calculation logic of the main scheme to capture and record the batch characteristic rate curve characterizing the current batch of raw materials. Before generating a new setpoint, the module extracts key characteristic parameters from the characteristic curve, such as the time integral value or peak occurrence time of the curve, and performs a logical comparison with a preset formula reference window. When the key characteristic parameters are within the formula reference window, the module generates a new ideal rate curve setpoint adapted to the characteristics of the current batch based on the characteristic curve and switches to control mode. If the comparison fails, the process is stopped and an alarm is triggered. This internal logic of the control system, which verifies the formula first and then adaptively sets the setpoint, prevents process mismatch caused by setpoint rigidity when facing high-frequency disturbances in raw material batches, and avoids the major production risk of incorrect adaptation due to catastrophic misfeeding. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the logic of the rate closed-loop control and setpoint adaptation of the present invention.

[0025] Figure 2 This is a comparison chart of batch characteristic rate curves of different batches of membrane preforms of the present invention.

[0026] Figure 3 This is a diagram showing the hardware components and signal flow architecture of the control system of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in further detail below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] This invention provides an online control system for the preparation of inorganic ultrafiltration membranes, deployed in a sintering furnace for preparing inorganic ultrafiltration membranes. It is used for high-temperature sintering of the membrane preform. During sintering, the organic binder and pore-forming agent within the membrane preform decompose thermally and are released into the furnace atmosphere. The system includes an atmosphere flow control unit, a gas analysis unit, and a control unit. The control unit can be a programmable logic controller (PLC) or a distributed control system (DCS). The atmosphere flow control unit is preferably a mass flow controller (MFC) installed on the main inlet pipe of the sintering furnace, electrically connected to the control unit to receive flow commands from the control unit and adjust the flow according to a predetermined inlet flow rate F. in Precise control of the combustion-supporting or protective atmosphere, such as air entering the sintering furnace, to control the F in The real-time measured value or set value is fed back to the control unit as a known parameter; the gas analysis unit, preferably a gas analyzer installed on the exhaust manifold of the sintering furnace, is a non-dispersive infrared (NDIR) sensor for measuring CO2, a product of organic combustion. It is electrically connected to the control unit and is used to continuously or periodically measure the real-time concentration C of the target released product in the sintering furnace exhaust. out , the C out The signal is transmitted to the control unit; the control unit is the core actuator of the control logic of this invention, electrically connected to the atmosphere flow control unit and the gas analysis unit, connected to the actuator of the sintering furnace, and is the heating power regulator of the sintering furnace, used to regulate the power applied to the heating components of the sintering furnace; the control unit has at least two switchable operating modes, control mode and characterization mode. One of its core functions is to execute closed-loop control logic based on the real process rate in control mode. This is accomplished within the control unit through the following steps: the control unit constructs process variables that can characterize the real reaction rate inside the membrane preform in real time, and directly uses the concentration signal C. out As a process variable, it is unreliable because it is affected by the intake flow rate F. in To address the issue of control signal distortion caused by varying dilution interference, the control unit is used to adjust the control signal based on the real-time concentration C of the target release agent. out and intake set flow rate F in Real-time calculation of the process variable PV, which represents the rate of release of the target substance. Rate This calculation is performed via PV. Rate =C out ×F in Executed in the manner in which PV Rate C is the process variable representing the rate at which the target mass is released. out For the real-time concentration of the target release, F in Set the intake flow rate to obtain PV (volume / time) decoupled from flow fluctuations. Rate .

[0029] The control unit acquires the preset value SP of the ideal rate curve.Rate (t), the SP Rate (t) is a target curve within the storage control unit, characterizing the change in the mass rate of the target released substance over time t, which is pre-calibrated using offline methods such as thermogravimetric analysis (TGA); the control unit executes a closed-loop control algorithm, such as a PID algorithm, based on PV. Rate With SP Rate The error between (t) is E = SP Rate (t)-PV Rate This generates a control output signal MV, which directly regulates the heating power regulator of the sintering furnace. When PV... Rate Below SP Rate When (t) occurs, the control unit automatically increases the heating power; conversely, it automatically decreases the heating power. The control system adaptively adjusts the furnace temperature, forcing PV... Rate Always track SP Rate (t); In the control system, in the face of fluctuations in the chemical properties of different batches of raw materials or possible misfeeding during production, it relies on a fixed SP. Rate (t) Control is rigid. To solve the problem of setpoint rigidity and mismatch, the control unit includes a setpoint adaptive module. This module performs online calibration and verification of the setpoint when the control unit switches to characterization mode. Characterization mode is typically triggered when the first piece of a new batch of preforms is produced. The setpoint adaptive module controls the actuator to disconnect the original rate closed-loop logic and execute a preset standard open-loop temperature program. This program can be a constant heating rate, for example, from room temperature to 600°C at a rate of 10°C / minute. During this open-loop heating process, the module reuses the PV calculation logic of the main scheme, using the target release rate PV. RateThe calculation results are recorded and stored in real time, showing the unique batch characteristic rate curve generated by the first membrane preform of the current batch. This curve is the chemical fingerprint of the new batch of raw materials under standard heating conditions. Before the control system generates new setpoints, a key logic verification step is to prevent correct adaptation to incorrect raw materials. The setpoint adaptation module is also used to extract one or more key characteristic parameters from the batch characteristic rate curve after obtaining it, before generating the setpoint for the ideal rate curve. In the simplified implementation of the control logic, the key characteristic parameters preferably include the time integral value of the batch characteristic rate curve, which physically corresponds to the total mass of organic matter in the current batch of membrane preforms. The control unit logically compares the key characteristic parameters with a preset formula baseline window corresponding to the current production formula. This window defines the allowable fluctuation range of qualified formula parameters; for example, the integral value should be between 5.0-5.5 grams, and the peak time should be between 35-40 minutes. Only when the key characteristic parameters are within the formula baseline window does the control unit determine that the current batch has a correct formula but drifting characteristics, and continues to execute subsequent steps. Based on the batch characteristic rate curve, the control unit generates an updated ideal rate curve setpoint SP through internal algorithms, such as peak identification, broadening, and smoothing. Rate (t), the control unit automatically switches back to control mode and uses the newly generated SP adapted to the current batch. Rate (t) Perform closed-loop control; the setpoint adaptive module is also used to: when the key characteristic parameter is outside the formula reference window, the control unit determines that a misfeed has occurred, generates an alarm signal to stop the standard open-loop temperature program.

[0030] The control unit is based on the batch characteristic rate curve PV Rate,C (t) Generate the ideal rate curve setpoint SP Rate,C At time (t), a constrained transformation procedure is executed in the control unit or connected engineering station, calling two preset boundary parameters corresponding to the current formulation process, namely the process safety rate upper limit Peak. Max Total time of the target process Target Peak Max Used to limit SP Rate,C (t) The maximum permissible rate at any point in time, Time Target Used to constrain the total duration of the transformed curve; the transformation procedure is implemented by the control unit acquiring the PV Rate,C Peak value of (t) C With Peak Max Comparison; if Peak C Not exceeding Peak Max PV Rate,C (t) after smoothing is used as SPRate,C (t); if Peak C Beyond Peak Max The control unit then executes peak clipping and mass conservation broadening algorithms to reduce PV Rate,C (t) All curves above Peak Max Partially truncated to Peak Max Calculate the integral value I of the mass of the truncated portion. diff According to the preset allocation function, such as with PV Rate,C (t) in Peak Max The following amplitudes are proportional, with I... diff Re-overlay to PV Rate,C (t) curve below Peak Max During the time period, the final generated SP Rate,C (t) curve, peak constraint at Peak Max Within, and within Time Target The total time integral value within the original PV Rate,C The total integral value of (t) remains consistent; in industrial control environments, the authenticity of the measured process variable PV is a prerequisite for closed-loop control. The control system of this invention also integrates correction mechanisms for two common types of measurement distortion problems. The first type of distortion is caused by ambient air leakage due to the non-absolute sealing of the sintering furnace body. The leaked air does not contain the target release material and will dilute the C in the exhaust manifold. out This leads to the control unit being based on a systematically underestimated PV. Rate To perform error control and correct this dilution distortion, the system also includes an oxygen analysis unit, such as a zirconia sensor, installed in the exhaust manifold to measure the oxygen concentration (O2) in the sintering furnace exhaust. out The control unit is also used to: acquire a preset reference oxygen concentration O in For example, 20.9% of standard air, based on O out Preset O in In addition to the known stoichiometric relationship of organic matter combustion consumption, a simplified model based on CHO chemical reaction equilibrium is embedded in the control logic to calculate the dilution calibration factor K in real time; the control unit, based on the dilution calibration factor K, calculates the target release mass rate PV. Rate The calculation is corrected; the control unit is used to adjust the calculation based on the real-time concentration C of the target release substance. out Calculate the true concentration C using the dilution calibration factor K. True The calculation method is C. True =C out ×K(O out O in Based on the true concentration C True and intake set flow rate F inCalculate the process variable PV of the corrected target release mass rate. True_Rate =C True ×F in Use this PV True_Rate Subsequent closed-loop control of the control mode is performed; the second type of distortion is caused by the combustion / protective atmosphere F used by the control system. in Caused by its own baseline drift, for example as F in The factory's ambient air, its own background CO2 concentration C in The PV calculated by the control system will fluctuate due to factors such as factory ventilation. Rate To correct this baseline drift, which originates at the source, the system also includes an intake analysis unit installed before the airflow control unit. The intake manifold is used to measure the intake set flow rate F. in The target emission concentration C of the inlet air before entering the sintering furnace in The control unit is also used to determine the target emission concentration C based on the intake air. in PV of the target release mass rate Rate The calculation is used for compensation; preferably, the control unit is used to execute the differential mass balance algorithm to calculate the real-time concentration C of the target release substance. out With the target concentration of inlet gas C in The difference ΔC = C out -C in Based on the difference ΔC and the intake set flow rate F in Calculate the process variable PV of the target release mass rate after compensation. Rate =ΔC×F in PV Rate Closed-loop control for control modes.

[0031] Furthermore, traditional process control typically relies on fixed time intervals for switching processes. This open-loop switching method cannot detect process lags caused by disturbances, and may incorrectly enter the next high-temperature process before organic matter is fully decomposed, leading to residual carbon defects. To address this end-point blindness problem in process control, the control system of this invention also performs information accompaniment reuse on the core variables of the main scheme; the control unit is also used to monitor the process variable PV of the target release rate while executing the rate closed loop of the control mode. Rate and PV Rate The amplitude is considered as a signal characterizing the degree of process completion; the control unit uses the process variable PV of the target release mass rate. Rate Compared with the preset process endpoint reference threshold Th End In comparison, the Th End It is a constant very close to zero characterizing that the organic matter has been physically decomposed; the process switching logic of the control unit is reconstructed as follows: when the process variable PV of the target release rate...Rate Below the process endpoint reference threshold Th End The current running time is greater than the preset minimum process time T. Minimal Only when the control unit triggers the process switching signal, instructing the sintering furnace to enter the next process, such as the high-temperature crystal preservation stage, T Minimal To prevent false triggering due to signal fluctuations in the early stages of the process, this closed-loop event-driven process control method ensures the integrity of process steps. The control system of this invention also includes a self-diagnostic mechanism for the control loop (not shown in the accompanying drawings), used to address C-related issues caused by gas analysis unit probe contamination or exhaust pipe ash accumulation during long-term system operation. out Signal dynamic response distortion, such as delay, occurs under this mechanism. The control unit is also used to periodically respond to trigger signals at the intake set flow rate F. in A small perturbation signal, such as a step signal, is superimposed on the signal; the control unit analyzes the real-time concentration C of the target release caused by this perturbation signal. out The response extracts implicit state parameters characterizing dynamic response distortion, such as response delay time t or response gain K. Based on the implicit state parameters, the control unit automatically adjusts one or more control parameters of its main control algorithm for generating the control output signal MV, such as integral time Ti or derivative time Td. This self-tuning of parameters ensures that the control loop maintains control responsiveness and stability when sensor or flow field characteristics change slowly.

[0032] Example 1: In a continuous production scenario of inorganic ultrafiltration membranes, the control system operates the sintering furnace according to a fixed programmed temperature rise curve, which is offline calibrated for batch A of standard membrane preforms with an organic binder content of 8%. When a process disturbance occurs during production, and batch B of membrane preforms with an organic binder content fluctuating to 10% enters the sintering furnace, the control system, using furnace temperature as a process variable, cannot detect changes in the material inside the membrane preforms. The system continues to execute the programmed temperature rise curve for batch A, causing the decomposition rate of organic matter inside batch B membrane preforms to run out of control at a specific stage of the programmed temperature rise. The released gas flux exceeds the tolerance limit of the membrane microstructure, resulting in cracking defects, and the control system is completely unaware of this out-of-control state. Switching the sintering furnace to the online control system of this invention, the control unit is in control mode, and the ideal rate curve SP of standard batch A obtained through offline calibration is stored internally. Rate (t), this curve defines the upper limit of the mass rate at which organic matter can safely decompose; the PID controller of the control unit no longer tracks temperature, but is based on E=SP Rate (t)-PV Rate The error-adjusting heating power regulator; when batch B of the same batch of membrane preforms enters the sintering furnace, the decomposition rate begins to rise sharply in the initial stage of heating; the C measured by the gas analysis unit outThe number of units increased rapidly accordingly, and the control unit was based on C. out and the known F in Real-time calculated PV Rate Instantly exceeded the internal storage SP Rate (t); The PID controller of the control unit then calculates the negative error E and automatically reduces the control output signal MV used to adjust the heating power regulator; the adaptive adjustment of the heating power by the control system suppresses the excessively rapid decomposition reaction inside the membrane preform, PV Rate Pull back SP Rate (t) is the set value; throughout the subsequent sintering process, the control system automatically seeks temporary furnace temperatures lower than the standard program setting through continuous negative feedback adjustment. For this batch of high binder content preforms, the overall organic matter decomposition process control system forcibly constrains the SP setting. Rate On the path defined by (t), membrane cracking caused by rate runaway is avoided, and adaptive compensation at the control system level is achieved for disturbances from different materials.

[0033] Example 2: This example verifies the adaptive control performance of the control system of the present invention in the face of raw material batch disturbances on a laboratory-scale tubular furnace platform. The platform includes a heating power regulator with a maximum power of 5kW, a mass flow controller (MFC) with a range of 0-20.0 SLM, a CO2 non-dispersive infrared (NDIR) gas analysis unit with a range of 0-2.0%, and a PLC system with an integrated control unit. This PLC system is programmable to switch between two control modes: Mode 1 (control group) executes traditional temperature process control, and Mode 2 (sample group of the present invention) executes rate closed-loop control as described in the specific implementation. Two membrane preform batches were prepared for the experiment: standard membrane preform batch A, with an organic binder content of 8.1 wt%; and high-content membrane preform batch B, with an organic binder content of 10.2 wt%. Batch B was used to simulate common raw material batch fluctuation disturbances in production. The temperature setpoint curve SP used in the control group control mode was... Temp (t) By performing thermogravimetric analysis (TGA) on batch A and calibrating based on process experience, the temperature was set to rise from room temperature to 600°C at a constant rate of 5°C / min; the ideal rate curve SP used in the sample group control method of this invention... Rate (t) Also based on the TGA data of batch A, the peak rate was set to 0.50 g / min; during the test, the intake set flow rate F of the atmosphere flow control unit was... in The constant value was 10.0 SLM. The experiment was conducted in four groups, with 100 membrane preform samples randomly selected from each group. The control system used two control methods to sinter the membrane preforms of batch A and batch B, respectively. The control unit recorded the peak target release rate PV reached in real time during the process. RateAfter sintering, the cracking rate of the film layer of each group of 100 samples was counted, and 5 samples were randomly selected to test the final residual carbon content (wt%). The test results are summarized in Table 1.

[0034] Table 1: Comparison Test Data of Control Methods

[0035]

[0036] Referring to Table 1, control group-1 (batch A) was used as a baseline, with a peak rate of 0.51 g / min, and both the cracking rate and residual carbon content were at the low levels allowed by the process. When control group-2 (batch B) was running, the temperature process control system was completely unaware of the material changes and executed a fixed SP. Temp (t), resulting in batch B with high organic content experiencing uncontrolled decomposition rate during heating, with the peak rate reaching 0.82 g / min, far exceeding the baseline value, leading to a surge in film cracking rate to 15% and control system failure; the closed-loop control of the operating rate of sample group-1 (batch A) of this invention showed results basically consistent with the baseline of control group-1, indicating that the rate control method can stably reproduce the standard process; the closed-loop control of the operating rate of sample group-2 (batch B) of this invention, when the control unit monitors PV Rate (0.54 g / min) attempting to exceed SP Rate When the rate is 0.50 g / min, the PID logic of the control system reacts immediately, automatically reducing the heating power output and suppressing the decomposition rate, so that the peak rate control system is constrained within the controllable range of 0.54 g / min. The final film cracking rate is only 2%, which is basically consistent with the 1% of the benchmark group.

[0037] Example 3: This example combines Figures 1 to 3 A description of an online control system for the preparation of an inorganic ultrafiltration membrane, such as... Figure 1 As shown, the logic includes a main control loop and a characterization adaptive loop: The main control loop uses the intake set flow signal from the atmosphere flow control unit and the real-time concentration signal of the target release agent from the gas analysis unit to construct the target release agent mass rate through the rate calculation module. This rate is compared with the ideal rate curve set value in the rate closed-loop control module to generate a control output signal to drive the heating power regulator actuator. The dilution distortion correction signal from the oxygen analysis unit and the baseline drift compensation signal from the intake analysis unit are also incorporated into the calculation and control logic. The characterization adaptive loop is triggered by a new batch of membrane embryos to enter the characterization mode. First, it executes the standard open-loop temperature program, uses the output of the rate calculation module to record the batch characteristic rate curve, extracts key characteristic parameters, such as time integral value and peak time, and compares them with the formulation reference window. If the result is within the window, the ideal rate curve set value is updated based on the batch characteristic rate curve for the main control loop to call. If the result is outside the window, an alarm signal is generated and the program is terminated.

[0038] like Figure 2 As shown, the graph plots time (in minutes) on the x-axis and the target release rate (in g / min) on the y-axis, with the x-axis ranging from 0 to 60 minutes and the y-axis ranging from 0 to 0.9 g / min. The graph illustrates the characteristic curves for batch A and batch B. From the shape of the two curves and the data points, it can be seen that both reach their respective peak rates at time 30. However, the peak rate of batch B (approximately 0.82 g / min) is higher than that of batch A (approximately 0.51 g / min). Throughout the entire time range of 0 to 60 minutes, the rate value of batch B consistently exceeds that of batch A. Figure 3 As shown, the process atmosphere intake gas flows through the atmosphere flow control unit and mass flow controller to form process intake gas and enters the sintering furnace. The process exhaust gas discharged from the sintering furnace flows to the exhaust port. The intake gas analysis unit, the gas analysis unit non-dispersive infrared sensor, and the oxygen analysis unit zirconia sensor measure the process intake gas or process exhaust gas respectively and send the signals to the control unit PLC / DCS. The control unit also communicates with the atmosphere flow control unit engineering station / HMI and outputs control signals to the actuator heating power regulator, which regulates the sintering furnace.

[0039] Example 4: This example illustrates the setpoint adaptive module. When the control system is first deployed or a completely new formula A is replaced, the control system establishes a formula baseline window and generates a standardized engineering calibration procedure for the initial ideal rate curve setpoint. The initial state of the calibration procedure is: the sintering furnace with the control system of this invention installed has been calibrated, the atmosphere flow control unit and the gas analysis unit have been calibrated, and the ideal rate curve SP of the control unit is... Rate (t) and the formulation baseline window are both empty; and N=20 baseline preform samples representing formulation A have been confirmed by offline laboratory methods; the control unit switches to characterization mode and locks in this mode; the operator sequentially feeds N=20 baseline preform samples into the sintering furnace; the control unit automatically executes a standard open-loop temperature program for each sample, set to linearly increase the temperature from 100℃ to 650℃ at a rate of 5℃ / min; throughout the sample heating process, the control unit uses an atmosphere flow control unit set to 10.0SLM to feed back F in C measured by the gas analysis unit out,i (t), and the batch characteristic rate curve PV is calculated and stored in real time. Rate,i After N=20 runs (t), the control unit or its connected engineering station automatically retrieves all N PV lines. Rate,i (t) curve data, execute parameter calibration algorithm.

[0040] Extracting curve PV Rate,iKey characteristic parameter of (t): Time integral value I i : , among which, T final The total duration of the standard open-loop temperature program, the integral value I i The total mass of organic matter is expressed in grams; the peak occurrence time T peak,i :T peak,i =argmax t (PV Rate,i (t)), peak time T peak,i The decomposition kinetics are characterized in minutes; the control unit extracts two sets of N key feature parameters {I1…I N} and {T peak,1 …T peak,N}, calculate the statistical mean μ I ,μ Tpeak with standard deviation μ was measured I =5.21g, =0.06g; μ Tpeak = 38.4 minutes, =0.5 minutes; Based on this statistical result, a formulation baseline window for formulation A is established, with the upper and lower limits set as the mean plus or minus three standard deviations μ ± 3σ. The control unit stores the formulation baseline window of I as [5.03g, 5.39g], and sets T peak The formulation baseline window is stored as [36.9 min, 39.9 min]; the control unit stores the batch characteristic rate curves PV for N=20 batches. Rate,i (t) Perform point-to-point averaging to generate a baseline rate curve. The baseline curve is processed using smoothing and broadening algorithms to generate the initial ideal rate curve SP. Rate (t), SP Rate (t) is stored together with the recipe reference window in the non-volatile memory area of ​​the control unit, thereby enabling the control unit to obtain control reference data for executing subsequent production tasks.

[0041] Example 5: When the control system, which has completed initial calibration and is in standby mode, receives a batch switching trigger signal for a new batch of preforms (batch C) and formulation A, the setpoint adaptive module of the control unit is activated. The control unit first switches to characterization mode and controls the actuator to execute the standard open-loop temperature program on the first preform of batch C. The control unit reuses the PV calculation logic and records the batch characteristic rate curve (PV) generated by the first preform in real time. Rate,C (t), after the open-loop procedure ends, the setpoint adaptive module immediately switches from PV. Rate,C Extracting key feature parameters I from (t) C and T peak,C and I Cand T peak,C The control unit performs a logical comparison with the formula A reference window stored internally in the control unit. When the comparison result is within the window, the control unit determines that the formula is correct and, based on this PV... Rate,C The (t) curve is used to generate and update a new ideal rate curve SP adapted to batch C through smoothing and broadening algorithms. Rate,C (t), the control unit automatically switches back to control mode and uses this updated SP. Rate,C (t) Perform closed-loop control on all subsequent preforms of batch C.

[0042] In another operating scenario of the control system, the system is used to compensate for measurement distortion of process variables in non-ideal industrial environments. When the control system is running stably in control mode, if there are fluctuations in the ambient air in the factory, the concentration C of the target released substance in the intake air measured by the intake air analysis unit will be affected. in When the baseline value fluctuates from 400ppm to 650ppm, the compensation logic of the control unit is triggered, and the PV is calculated. Rate The core algorithm automatically extracts from PV Rate =C out ×F in Switch to differential compensation algorithm PV Rate =(C out -C in )×F in The baseline drift is dynamically isolated from the process variables in real time; the oxygen analysis unit within the control system continuously monitors the exhaust oxygen concentration O. out , when O out The measured value, taking 20.1% as an example, is compared with the control unit based on known O in Taking 20.9% as an example and the PV after differential compensation Rate When the calculated theoretical oxygen consumption is inconsistent, the control unit determines that an air leak exists and automatically activates the dilution calibration logic. The control unit is based on O out With O in The deviation is considered, and the dilution calibration factor K is calculated in real time based on the stoichiometric relationship of combustion consumption. Taking K = 1.05 as an example, the K value is applied to the core algorithm for diluting C. out The restoration correction system utilizes a dual logic of differential compensation and dilution calibration in parallel to ensure the constructed PV... Rate Maintain accuracy as a process variable when faced with the dual disturbances of baseline drift and furnace leakage.

[0043] Example 6: This example is a calibration procedure for determining the key operating parameters required for the closed-loop control logic and process control logic of the control unit during deployment or long-term operation. The parameters include the process endpoint reference threshold Th. End and health benchmarks for self-diagnostic mechanisms The PID parameters Ti of the main control algorithm orig 、Td orig ; Process endpoint reference threshold Th End The calibration procedure is as follows: After one sintering cycle in the sintering furnace and the temperature drops to the process standby temperature of 100°C, under no-load conditions with no preforms in the furnace chamber, start the atmosphere flow control unit of the control system, and set the standard production flow rate F. in =10.0SLM introduces atmosphere into the furnace and starts the gas analysis unit; the control unit continuously monitors the real-time concentration C of the target release product output by the gas analysis unit. out Signal, collect data points for at least 10 minutes; calculate C under no-load conditions. out Statistical mean μ of the signal noise With standard deviation σ noise Based on these statistical results, the process endpoint baseline threshold Th is automatically calculated and stored. End The calculation formula is Th End =μ noise +3×σ noise The End The value represents the baseline at which the system determines the process is complete.

[0044] Self-diagnostic mechanism baseline parameters Ti orig 、Td orig The calibration procedure is as follows: After the control system is installed and debugged, and all sensors and pipelines are in a clean and uncontaminated state, the control unit performs a baseline response test; at time t0, the control unit controls the air flow rate at the intake set flow rate F. in A small perturbation signal is superimposed, increasing from 10.0 SLM to 10.5 SLM; the control unit monitors the real-time concentration C of the target release substance at high frequency. out The response, analysis of C out At time t1, when the signal begins to decline due to concentration dilution, latent state parameters in the healthy state are extracted, along with the health baseline value. =t1-t0, measured =1.5 seconds; Under this healthy state, the control engineer controls the main speed control loop of the control system, E=SP. Rate -PV Rate Perform PID parameter tuning to obtain a set of control parameters Ti orig and Td orig and will Ti orig 、Td orig This data is stored as a baseline; during subsequent long-term system operation, when the control unit executes this self-diagnostic mechanism, it extracts new latent state parameters that have increased due to sensor contamination. hour, =3.0 seconds, the adaptive logic of the control unit is activated. Based on the stored reference, the control unit adjusts the PID parameters online using the following control algorithm: Ti new =Ti orig ×( ) and Td new =Td orig × The main control algorithm of the control system automatically compensates for the dynamic response distortion of the measurement link.

[0045] 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.

[0046] Finally, it should be noted that 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An online control system for the preparation of inorganic ultrafiltration membranes, characterized in that, Includes an atmosphere flow control unit, a gas analysis unit, and a control unit: The control unit includes a setpoint adaptive module and is electrically connected to the atmosphere flow control unit and the gas analysis unit. The atmosphere flow control unit is used to control the air intake of the sintering furnace according to the set air intake flow rate; The gas analysis unit is used to measure the real-time concentration of target emissions in the exhaust gas from the sintering furnace; The control unit is used to calculate the process variable of the mass rate of the target release substance in real time based on the real-time concentration of the target release substance and the set flow rate of the inlet air in control mode, obtain the set value of the ideal rate curve, and generate a control output signal to adjust the actuator of the sintering furnace based on the error between the process variable of the mass rate of the target release substance and the set value of the ideal rate curve. The setpoint adaptive module is used to control the actuator to execute a preset standard open-loop temperature program in characterization mode, and at the same time, record the batch characteristic rate curve using the calculation results of the process variable of the target release mass rate. The setpoint adaptation module is also used to extract key feature parameters from the batch characteristic rate curve before generating the setpoint of the ideal rate curve. The key feature parameters include the time integral value of the batch characteristic rate curve and the peak occurrence time of the batch characteristic rate curve. The key feature parameters are compared with a preset recipe benchmark window. When the key feature parameters are within the recipe benchmark window, the setpoint of the updated ideal rate curve is generated based on the batch characteristic rate curve.

2. The online control system for inorganic ultrafiltration membrane preparation according to claim 1, characterized in that, The control unit is used to control the PV in control mode. Rate =C out ×F in The calculation method calculates the process variable of the target release rate; where PV Rate C is the process variable representing the rate at which the target mass is released. out For the real-time concentration of the target release, F in Set the intake airflow.

3. The online control system for inorganic ultrafiltration membrane preparation according to claim 1, characterized in that, The actuator is the heating power regulator of the sintering furnace.

4. The online control system for inorganic ultrafiltration membrane preparation according to claim 1, characterized in that, The setpoint adaptive module is also used to generate an alarm signal to abort the standard open-loop temperature program when key characteristic parameters are outside the formulation baseline window.

5. The online control system for inorganic ultrafiltration membrane preparation according to claim 1, characterized in that, The system also includes: an oxygen analysis unit for measuring the oxygen concentration in the exhaust gas of the sintering furnace, wherein the control unit is also used to obtain a preset reference oxygen concentration; calculate a dilution calibration factor based on the exhaust oxygen concentration, the preset reference oxygen concentration and the known stoichiometric relationship of organic matter combustion consumption; and correct the calculation of the process variable of the target release rate based on the dilution calibration factor.

6. The online control system for inorganic ultrafiltration membrane preparation according to claim 5, characterized in that, The control unit is used to: calculate the true concentration based on the real-time concentration of the target release agent and the dilution calibration factor; and calculate the process variable of the corrected target release agent mass rate based on the true concentration and the inlet set flow rate.

7. The online control system for inorganic ultrafiltration membrane preparation according to claim 1, characterized in that, The system also includes: an intake analysis unit for measuring the concentration of the target release product in the intake air before it enters the sintering furnace at the set intake flow rate; wherein, the control unit is also used to compensate for the calculation of the process variable of the target release product mass rate based on the intake target release product concentration.

8. The online control system for inorganic ultrafiltration membrane preparation according to claim 7, characterized in that, The control unit is used to: calculate the difference between the real-time concentration of the target release agent and the concentration of the target release agent in the intake air; and calculate the compensated target release agent mass rate as a process variable based on the difference and the intake air set flow rate.

9. The online control system for inorganic ultrafiltration membrane preparation according to claim 1, characterized in that, The control unit is also used to monitor the process variable of the target release mass rate; compare the process variable of the target release mass rate with a preset process endpoint reference threshold; and trigger a process switching signal when the process variable of the target release mass rate is lower than the process endpoint reference threshold and the current running time is greater than the preset minimum process time.

Images