Molecular sieve separation system for medical oxygen production

Abstract

The present application relates to the separation technical field, disclose a kind of molecular sieve separation system for medical oxygen production, comprising: adsorption separation group, fluid control valve group, pressure monitoring unit and self-adapting control center, self-adapting control center executes capacity locking logic and regeneration clamping logic based on fluid impedance fingerprint feature, real-time monitoring actual pressure charging duration of adsorption pressure charging stage and calculating the deviation value with reference adsorption duration, generate primary switching instruction;Real-time residual desorption pressure of another adsorption bed is obtained simultaneously and compared with regeneration end-point pressure threshold value, when meeting the condition, output final step sequence switching instruction, the present application realizes the self-adapting locking of molecular sieve real adsorption capacity by identifying adsorption capacity saturation feature and decoupling gas source fluctuation.

Description

Technical Field

[0001] This invention relates to a molecular sieve separation system for medical oxygen generation, belonging to the field of separation technology. Background Technology

[0002] Currently, medical pressure swing adsorption (PSA) technology is widely used due to its mature process and controllable energy consumption. The mechanism utilizes the selective adsorption characteristics of zeolite molecular sieves for nitrogen, separating high-purity oxygen from the air through periodic pressure adsorption and depressurization desorption cycles. Traditional control strategies often employ preset fixed-time open-loop control logic, setting valve switching times according to design conditions to maintain continuous oxygen production. This fixed-time logic is based on the assumption of constant adsorbent performance. However, in actual long-term operation, the adsorption capacity of the porous molecular sieve adsorption medium is affected by ambient temperature fluctuations, trace moisture intrusion, and nonlinear factors such as natural lattice aging, exhibiting a dynamic decay characteristic. When the actual adsorbent capacity decreases due to aging, but the system continues to execute the original air intake duration, the nitrogen adsorption front exceeds the bed safety boundary, causing a drop in product gas purity. Furthermore, reserving too much time margin to cope with worst-case conditions leads to unsaturated adsorption capacity being idle, reducing raw material air utilization and increasing unit oxygen production energy consumption.

[0003] To address timing mismatch, existing technologies employ pressure transmitters for threshold control. However, in complex medical gas supply scenarios, simple pressure threshold monitoring faces multi-physical field coupling. Mechanical wear of gas source equipment leads to a decrease in gas supply flow rate, while adsorbent aging causes changes in adsorption rate, resulting in an aliased response on a single pressure dimension. Long-term vibration in mobile or modular oxygen generators can easily cause bed pulverization, and the densification of the physical structure leads to a sharp increase in flow resistance. If the control system cannot distinguish between chemical adsorption failure and physical flow channel blockage, it is prone to making incorrect periodic adjustment decisions or even causing equipment overpressure paralysis. The stability of pressure swing adsorption systems is not only limited by control timing or pressure measurement accuracy. Some existing technologies have attempted to introduce additional structural components to improve the stability of the gas flow rate, but these mechanical methods still cannot solve the fundamental problem of decreased separation performance. For example, the utility model patent with authorization announcement number CN216909756U discloses a molecular sieve oxygen generation separation and equalization device for medical oxygen generators. It sets an elastic flow equalization plate at the top of the molecular sieve tower to achieve physical buffering and stabilization of the outlet oxygen flow. This is essentially a passive downstream adjustment to address user discomfort caused by gas production fluctuations. It does not provide real-time monitoring and control of core process parameters such as molecular sieve adsorption capacity decay and nitrogen breakthrough, and cannot guarantee the system's energy efficiency and long-term purity safety.

[0004] Therefore, based on the dynamic response characteristics of fluids in porous media, constructing an adaptive separation control strategy that can lock the true adsorption capacity in real time, decouple gas source disturbances, and sense the health of the bed structure is the technical problem to be solved by this invention. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A molecular sieve separation system for medical oxygen generation, comprising:

[0006] The adsorption separation unit comprises a dual-tower adsorption bed filled with zeolite molecular sieves, which alternately performs pressure swing adsorption cycles to separate oxygen from the air.

[0007] Fluid control valve assembly is used to regulate the path of gas entering and exiting the adsorption separation unit;

[0008] The pressure monitoring unit is located in the adsorption separation group and is used to collect the internal pressure signal of the adsorption bed;

[0009] The adaptive control center is connected to the fluid control valve group and pressure monitoring unit. It executes a capacity locking and regeneration clamping strategy, which includes: during the adsorption pressurization phase of the adsorption bed, real-time monitoring of the actual pressurization time required for the internal pressure signal to rise from a first preset pressure value to a second preset pressure value; calculating the deviation between the actual pressurization time and a pre-stored baseline adsorption time; generating a primary switching command when the deviation indicates that the actual pressurization time is shorter than the baseline adsorption time and exceeds a preset threshold; simultaneously, acquiring the real-time residual desorption pressure of another adsorption bed in the regeneration phase and comparing it with a preset regeneration endpoint pressure threshold; outputting a final step switching command when the real-time residual desorption pressure is lower than the regeneration endpoint pressure threshold to drive the fluid control valve group to terminate the current adsorption pressurization phase and start the regeneration phase; and blocking the primary switching command and maintaining the current fluid state until the real-time residual desorption pressure meets the regeneration endpoint pressure threshold if the real-time residual desorption pressure is higher than the regeneration endpoint pressure threshold.

[0010] Preferably, the adaptive control center is also used to execute the dual-zone decoupling logic of fluid and adsorption kinetics: dividing the adsorption pressurization stage into a flow resistance-dominated zone in the low-pressure section and an adsorption-dominated zone in the high-pressure stabilization section; calculating the first pressure rise rate of the internal pressure signal in the flow resistance-dominated zone and the second pressure rise rate in the adsorption-dominated zone; and using the following formula to calculate the state decoupling factor used to orthogonally distinguish between the mechanical fluctuations of the gas source and the chemical decay of the adsorbent. : ,in, For the first boost rate, The second boost rate; the adaptive control center detects the state decoupling factor. When the change relative to the reference value exceeds a preset chemical decay threshold, a capacity lock and regeneration clamp strategy is implemented to adjust the cycle period; if a decrease in the first boost rate and the state decoupling factor are detected... If the mechanical fluctuation range is maintained, the current cycle will remain unchanged and an abnormal gas source signal will be generated.

[0011] Preferably, the adaptive control center is also used to execute the pressure equalization potential energy adaptive cutoff logic: in the pressure equalization stage of the gas pressure balancing operation between the two adsorption beds of the adsorption separation group, the instantaneous pressure difference between the two adsorption beds and its time decay rate are calculated in real time; the time decay rate is compared with the preset effective mass transfer flux threshold; when the time decay rate drops below the effective mass transfer flux threshold, regardless of whether the preset duration of the current pressure equalization step has been exhausted, an instruction is immediately generated to terminate the pressure equalization stage.

[0012] Preferably, the adaptive control center is also used to execute bed structure health diagnosis logic: during the regeneration and desorption stage of the adsorption bed, the pressure relief response curve of the internal pressure signal decreasing over time is monitored; the flow resistance characteristic slope of the pressure relief response curve is extracted and compared with the preset standard porosity flow resistance model; when the flow resistance characteristic slope shows that the pressure relief rate is lower than the standard value and the actual pressurization time of the adsorption pressurization stage is shorter than the baseline adsorption time, it is determined that the adsorption bed has undergone physical structural densification or pulverization; in response to the determination, the adaptive control center generates a structural fault alarm and locks the current cycle adjustment strategy.

[0013] Preferably, the baseline adsorption time is a dynamic parameter automatically updated by the adaptive control center based on the optimal adsorption efficiency condition in the system's historical operating data; the adaptive control center is also used to execute the ambient temperature trend compensation logic, which automatically extends the preset adsorption time of subsequent cycles when the actual pressurization time of multiple consecutive cycles is longer than the baseline adsorption time.

[0014] Preferably, when maintaining the current fluid state, the adaptive control center controls the adsorption bed currently performing adsorption to enter a pressure-holding hovering state, and simultaneously controls the adsorption bed currently performing regeneration to maintain the exhaust valve open until the real-time residual desorption pressure drops below the regeneration endpoint pressure threshold, then releases the shield and executes the final step sequence switching command.

[0015] Preferably, the fluid control valve group includes an inlet valve, an exhaust valve, and a pressure equalization valve; the adaptive control center executes the pressure swing adsorption cycle by adjusting the opening and closing sequence of the inlet valve and the exhaust valve; the pressure monitoring unit is a pressure transmitter installed at the product gas outlet of the adsorption bed, which is used to collect pressure change data at the top of the bed that characterizes the movement characteristics of the adsorption front.

[0016] Preferably, the flow resistance-dominant region is defined as the pressure range from the starting point to 30% of the working pressure; the adsorption-dominant region is defined as the pressure range from 70% to 90% of the working pressure.

[0017] Preferably, the adaptive control center is configured with fault mode classification logic. This logic uses the shortening of the actual pressurization time as the primary criterion and the slope of the flow resistance characteristic as the secondary criterion: if the secondary criterion shows that the depressurization rate is normal, it is classified as a chemical aging fault and a cycle shortening strategy is triggered; if the secondary criterion shows that the depressurization rate is slow, it is classified as a physical pulverization fault and a shutdown maintenance alarm is triggered.

[0018] Preferably, the adsorption separation group adopts a dual-tower parallel structure, and the adaptive control center independently monitors the pressure characteristics of each adsorption tower and independently establishes its own benchmark adsorption time to compensate for the imbalance of adsorption performance between the two adsorption towers caused by differences in packing density or valve response delay.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. In the molecular sieve separation system for medical oxygen production, a non-invasive adsorption front position sensing mechanism is established by utilizing the physical difference between the adsorption throughput effect in the unsaturated stage and the volume hardening effect in the saturated stage of the porous adsorption medium. During the pressure swing adsorption cycle pressurization stage, the rapid adsorption of nitrogen by the adsorption bed inhibits the rate of increase of the gas phase partial pressure in the tower. When the adsorbent approaches saturation or the specific surface area decreases due to aging, the inhibition effect weakens, manifested as a steepening of the pressure rise rate. The system monitors the pressure integral area or pressurization time in real time and compares it with the benchmark kinetic model to directly identify the physical precursors of the adsorption mass transfer zone breaking through the bed safety boundary. The mechanism shifts the separation cycle switching logic from the rigid time dimension to the dimension of the actual remaining capacity of the adsorbent, ensuring that the nitrogen adsorption front is always locked within the safe range before the bed outlet under nonlinear operating conditions such as adsorbent moisture, aging, or ambient temperature fluctuations. This eliminates the risk of product gas purity dropping due to media performance drift and avoids wasting raw material air by reserving too much time margin to cope with the worst operating conditions.

[0021] 2. To address the overlapping issues of altered pressurization characteristics caused by both mechanical attenuation of the gas source equipment and chemical aging of the adsorbent, this invention constructs a bidirectional feature extraction logic based on pressure ranges. Utilizing the physical characteristics of the adsorption bed, where the low-pressure section is primarily driven by gas-filling fluid dynamics and the high-pressure section by adsorption-competitive mass transfer dynamics, the system extracts the pressurization rates of the flow resistance-dominated region and the adsorption-dominated region respectively and calculates the dimensionless ratio. This ratio serves as an intrinsic decoupling parameter, orthogonally distinguishing between the overall decrease in gas source flow rate caused by compressor wear or filter blockage, and the accelerated pressurization at the end of adsorption caused by molecular sieve lattice failure. This mechanism is based on the logical stability of the separation system under harsh gas source conditions, preventing the control center from misjudging insufficient mechanical gas supply as excessive adsorption capacity and incorrectly extending the adsorption time, thus ensuring the exclusive accuracy of separation timing decisions under complex energy supply environments.

[0022] 3. Utilizing the pure physical fluid response characteristics of the regeneration and desorption stage, an independent monitoring dimension for the physical structural integrity of the adsorption bed is constructed. Since the gas discharge rate during the desorption process is mainly limited by the physical porosity of the bed and the flow resistance of the pipeline, and is weakly correlated with the chemical adsorption performance, the system captures the pressure drop characteristic curve at the moment the exhaust valve opens. By comparing it with the standard porosity flow resistance model, it identifies the flow channel blockage characteristics caused by the mutual grinding and pulverization or densification of molecular sieve particles. The diagnostic mechanism complements the capacity monitoring mechanism of the adsorption stage, enabling accurate classification of two failure modes: chemical adsorption failure and physical structural collapse. This allows the system to not only adaptively compensate for routine aging but also trigger structural blockage alarms for potential equipment failures caused by pulverization and blockage, thereby improving the operational safety of medical oxygen supply equipment throughout its entire life cycle. Attached Figure Description

[0023] Figure 1 This is a diagram of the adaptive control logic architecture of the system based on fluid impedance characteristics according to the present invention.

[0024] Figure 2 This is a comparison diagram of the pressure relief response characteristics of the adsorption bed under normal and pulverized conditions in this invention;

[0025] Figure 3 This is a schematic diagram of the physical topology and closed-loop control connection of the dual-tower separation system of the present invention. Detailed Implementation

[0026] The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Throughout this specification, unless otherwise stated, all percentages are weight percentages, all pressure values ​​are gauge pressures, and all temperatures are degrees Celsius. 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 invention.

[0027] This invention provides a molecular sieve separation system for medical oxygen generation, comprising an adsorption separation group, a fluid control valve group, a pressure monitoring unit, and an adaptive control center. These components are connected via electrical or fluid pipelines to form a closed-loop controlled pressure swing adsorption (PSA) oxygen generator. The adsorption separation group includes a first adsorption tower and a second adsorption tower connected in parallel, each filled with a zeolite molecular sieve for separating oxygen and nitrogen, such as lithium-based molecular sieve Li-LSX. The fluid control valve group includes an inlet valve and an outlet valve connected to the bottom of each adsorption tower, and a pressure equalization valve connected between the two towers, used to switch the airflow path to perform adsorption, pressure equalization, and regeneration steps. The pressure monitoring unit includes pressure transmitters located at the product gas outlets of the first and second adsorption towers, used to collect real-time internal pressure signals from the top of the bed. The sampling frequency is no less than 10Hz to capture the dynamic characteristics of pressure changes. The adaptive control center uses an industrial-grade microcontroller, such as an ARM-based MCU or PLC, to receive pressure signals and drive the fluid control valve group according to the built-in control logic. Addressing the technical problem that fixed timing cannot adapt to the performance degradation of molecular sieves in existing technologies, this system implements an adaptive capacity locking procedure based on the charging impedance characteristic spectrum. This procedure is based on the physical difference between the gas flow effect when the adsorbent is unsaturated and the volume hardening effect when it is saturated. The adaptive control center executes the following logical steps: It performs a baseline fingerprint establishment step. During the first 10 to 50 operating cycles after the system's initial startup or after replacing the adsorbent, the control center records the pressure inside the adsorption tower from the first preset pressure value under standard operating conditions, i.e., an ambient temperature of 25℃ and a standard inlet pressure. If the pressure rises from 0.1 MPa to the second preset pressure value For example, the average time required for 0.5 MPa, and store this average as the baseline adsorption time. This parameter is used to characterize the standard adsorption kinetics of nitrogen by the molecular sieve in a healthy state.

[0028] Secondly, real-time impedance monitoring and deviation adjudication are performed. During each subsequent adsorption half-cycle, the control center times and measures the current adsorption tower pressure in real time. Rise to Actual charging time The control center uses formulas Calculate the deviation ratio When the calculated When the pressure exceeds the preset saturation threshold, such as 5%, it indicates that the effective adsorption capacity of the adsorbent has decreased, and the nitrogen adsorption front is about to break through the bed safety boundary. At this point, the control center generates a primary switching command to prepare to terminate the current adsorption pressurization stage. To prevent incomplete regeneration on the other side due to a shortened cycle on one side, the system immediately executes the regeneration endpoint pressure clamping procedure after generating the primary switching command. The control center reads the real-time internal pressure of the other adsorption tower, which is in the regeneration stage, i.e., the desorption or cleaning state, i.e., the real-time residual desorption pressure. The control center will With the preset regeneration endpoint pressure threshold For example, 0.02 MPa, close to atmospheric pressure, is compared, when the following conditions are met. Only when the conditions are met will the control center output the final sequence switching command, driving the fluid control valve group to perform valve switching. The control center blocks the primary switching command and controls the tower currently in adsorption mode to enter a pressure-holding hovering state, i.e., closing the inlet valve, keeping the exhaust valve closed, and simultaneously keeping the exhaust valve of the other tower open, until the pressure drops to... The following ensures that the lower limit of the shortened separation cycle is constrained by the minimum time boundary required for physical exhaust. Addressing the technical challenge of potential misjudgments due to mechanical attenuation of the gas source equipment, the adaptive control center further implements a dual-zone decoupling procedure for fluid and adsorption kinetics. This divides the adsorption pressurization process into two characteristic zones in terms of pressure: a flow resistance-dominated zone and an adsorption-dominated zone. The flow resistance-dominated zone is set as the range from the pressure initiation point to 30% of the working pressure, while the adsorption-dominated zone is set as the range from 70% to 90% of the working pressure. The control center calculates the average pressure rise rate of the pressure signal in the flow resistance-dominated zone. and the average pressurization rate in the adsorption-dominant region The control center calculates the state decoupling factor. .

[0029] The logical decision subroutine is as follows: If detected And the historical moving average shows a downward trend, for example, a drop of more than 10%, while If the value changes relative to the reference value within a preset mechanical fluctuation range (e.g., fluctuation less than ±2%), the control center determines it as a decrease in gas source flow. In this case, instead of shortening the adsorption time, an air source maintenance alarm is generated. Basically constant, but If the pressure increases beyond the preset chemical decay threshold, it is determined that the molecular sieve adsorption capacity has decreased, and the system executes the aforementioned capacity locking strategy to shorten the cycle time. Furthermore, to address the pressure equalization efficiency drift caused by dynamic adjustment of the adsorption cycle, this system implements an adaptive cutoff procedure for pressure equalization potential energy. During the pressure equalization phase, the control center collects the pressure values ​​of both towers at high frequency. and Real-time calculation of absolute pressure difference and time decay rate The system presets an effective mass transfer flux threshold. Through experimental calibration, the balance point corresponding to oxygen recovery rate and impurity diffusion risk was determined when... Drop to below At this time, the control center sends a command to close the pressure equalization valve, terminating the pressure equalization step without waiting for the preset pressure equalization time to expire. Finally, for latent faults caused by molecular sieve pulverization, the system integrates a bed structure health diagnosis procedure. In the initial stage of the regeneration and desorption step in the adsorption tower, for example, within 0.5 seconds after the exhaust valve is opened, the control center monitors the pressure relief response curve of the tower pressure decreasing over time and extracts the characteristic slope of the flow resistance. The control center compares the slope with a preset standard porosity flow resistance model. If the system determines that the adsorption stage needs to be shortened (i.e., the pressurization is accelerated), and simultaneously, during the desorption stage, it monitors... If the pressure is less than the standard value, the pressure relief becomes slower, exhibiting a long tail characteristic. The control center determines that the bed has undergone physical pulverization or densification blockage. At this time, the control center triggers a structural fault alarm and locks the current cycle parameters to prevent system overpressure caused by blind adjustments.

[0030] Example 1: In the application scenarios of oxygen production cabins in field hospitals or remote high-altitude areas, environmental conditions fluctuate drastically, with diurnal temperature differences exceeding 20 degrees Celsius. Furthermore, because the cabin's power supply system is driven by a diesel generator, voltage fluctuations cause irregular mechanical decreases in the output flow rate of the supporting air compressor. Simultaneously, long-term high-frequency vibration causes microstructural loosening and pulverization of the molecular sieve bed within the adsorption tower, resulting in nonlinear dynamic drift of the bed flow resistance. Under these conditions, traditional fixed-time step control systems cannot detect the immediate decay of the adsorbent's effective capacity, leading to frequent breaches of the bed by the nitrogen adsorption front. Oxygen purity fluctuates significantly between 93% and 85%, seriously threatening the safety of medical oxygen. When the system faces these complex conditions, the adaptive control center of this invention executes a capacity locking strategy. The control center monitors the first adsorption tower in real time from a first preset pressure value... (0.1MPa) rises to the second preset pressure value Actual charging time (0.5MPa) Because the molecular sieve vibrates for a long time, some of the crystal lattices become damp and age, resulting in a decrease in the adsorption rate of nitrogen, which manifests as an accelerated increase in pressure inside the tower. Shorten to the baseline adsorption time The control center calculated the deviation ratio as 90%. If the adsorption capacity exceeds the 5% threshold, it is determined that the adsorption capacity is saturated, and a primary switching instruction is immediately generated to prepare for early termination of the adsorption step.

[0031] However, mechanical fluctuations in the air compressor flow rate did not interfere with this determination. The system simultaneously executed the dual-zone decoupling logic of fluid and adsorption kinetics, calculating the pressure rise rate from the pressure initiation point to 30% of the working pressure in the flow resistance-dominated zone. and the pressurization rate at 70% to 90% of the working pressure in the adsorption-dominant range. Although the intake airflow rate decreased due to voltage fluctuations, The adsorption rate decreases, but the accelerated pressure rise at the end of adsorption due to molecular sieve aging becomes more significant, increasing the state decoupling factor. The pressure still exceeded the chemical decay threshold. Based on this, the control center accurately identified adsorbent performance degradation as the dominant factor, eliminated interference from gas source fluctuations, and continued to implement the decision to shorten the cycle. At the moment the primary switching command was generated, the system triggered the regeneration endpoint pressure clamping mechanism, and the control center monitored the real-time residual desorption pressure of the second adsorption tower on the opposite side. Because the molecular sieve inside the tower undergoes pulverization, increasing flow resistance and slowing down the exhaust rate, at this time... Still above the regeneration endpoint pressure threshold (0.02MPa), the control center disables the primary switching command and controls the first adsorption tower to enter the pressure holding and hovering state until the second adsorption tower is completely emptied. Only then is the final step switch performed. This action ensures that the thoroughness of regeneration is not sacrificed in the extreme case where the adsorption cycle is forced to be shortened significantly, and avoids systemic paralysis caused by the accumulation of residual nitrogen. Under the control of the above adaptive procedure, despite the dual disturbances of adsorbent aging and gas source fluctuations, the purity of the system output oxygen quickly and steadily recovers and locks in the medical standard range of 93%±1%, avoiding the risk of purity drop.

[0032] Example 2: To verify the actual control effect and performance advantages of the present invention under complex working conditions, a full-scale pressure swing adsorption (PSA) oxygen generation test platform was built, including two adsorption towers filled with Li-LSX molecular sieves, and supporting solenoid valve groups and pressure monitoring units. To simulate interference factors in real-world scenarios, two controllable variables were introduced into the experiment: first, the air compressor speed was modulated by a frequency converter to simulate the random change in the intake airflow rate caused by power supply voltage fluctuations (the fluctuation range was set to ±20% of the rated flow rate); second, a trace amount of water vapor (relative humidity 60%) was injected into the air inlet of the adsorption tower to accelerate the chemical aging process of the molecular sieve, and in the later stage of the experiment, a mechanical vibration table was used to simulate vehicle vibration to induce bed pulverization. The core parameters of the experiment were set according to strict engineering trade-off logic. The deviation threshold in the capacity lock-in criterion was set to 5%. This value was chosen based on the following considerations: if the threshold is too low, for example, 1%, the system is very susceptible to measurement noise interference from the pressure sensor itself, resulting in malfunctions; if the threshold is too high, for example, 10%, it may lead to switching lag, causing the nitrogen front to penetrate the bed. In addition, the state decoupling factor... The chemical decay threshold was set to 1.2, which was determined through previous calibration experiments. Above this value, the relative increase in the pressurization rate at the end of adsorption exceeded the linear change range caused by flow rate fluctuations alone, thus it can be determined with high confidence that the adsorption capacity decayed.

[0033] The experiment was conducted in two phases. The first phase was a baseline control test, where the system used traditional fixed-time step control with a constant adsorption time of 30 seconds. The second phase was an adaptive control test, where the system switched to the control logic of this invention. Throughout the experiment, the system continuously collected data on the product's gas oxygen concentration, adsorption tower pressure curve, and energy consumption per unit of oxygen. To accurately reflect the electromagnetic environment of the industrial site, Gaussian white noise with a signal-to-noise ratio of 20dB was superimposed on the pressure sensor signal. In the first phase, as the simulated aging time progressed, the molecular sieve adsorption capacity gradually decreased. Data showed that after 100 hours of operation, the oxygen purity began to show a significant periodic drop, with the lowest value falling below 88%. Even with a normal gas flow rate, the fixed time step failed to detect the movement of the adsorption front, leading to over-adsorption. After introducing flow rate fluctuation interference, the purity fluctuation further intensified, with a standard deviation exceeding 3.5%. In the second phase, the system activated the adaptive control logic. Even under the same simulated aging and flow rate fluctuation conditions, the control center performed real-time calculations... and The adsorption time is dynamically adjusted based on the value.

[0034] Table 1: Comparison of Key Performance Indicators under Different Operating Conditions

[0035]

[0036] Referring to Table 1, under the harsh operating conditions of control group B, fixed timing control could no longer maintain qualified oxygen purity, and energy consumption increased. However, in the experimental group of this invention, despite facing the same operating challenges, the average oxygen purity quickly recovered to 93.2%, and the standard deviation of fluctuation was compressed to 0.6%, slightly higher than that of control group A under ideal operating conditions. The unit energy consumption was reduced by about 13% compared to control group B. The system eliminated the waste of compressed air caused by continued air intake after the adsorbent was saturated. In addition, the experiment also captured the action characteristics of the regeneration clamping mechanism. During the period when exhaust was blocked due to simulated bed pulverization, the monitoring data showed that the switching command of the adsorption tower was delayed by an average of 1.5 seconds until the pressure of the opposite tower dropped below 0.02 MPa. This small timing adjustment avoided incomplete desorption caused by residual high-pressure nitrogen.

[0037] Example 3: This example combines Figures 1 to 3 A description of a molecular sieve separation system for medical oxygen generation, such as... Figure 1As shown in the figure, the closed-loop control architecture constructed in this figure takes the adaptive control center as the decision core. On the one hand, it senses the system status by receiving the pressure feedback signal P(t) collected from the internal adsorption separation group by the pressure monitoring unit. On the other hand, it sends drive commands to the fluid control valve group, which includes the inlet valve, exhaust valve and pressure equalization valve, to adjust the fluid path of the raw material air entering the first adsorption tower or the second adsorption tower and finally producing the product oxygen. During this operation, the adaptive control center executes four core logics based on the fluid impedance fingerprint characteristics in parallel. Among them, the capacity locking logic is responsible for monitoring the actual pressurization time and the reference deviation and generating the primary switching command; the dual-zone decoupling logic is responsible for calculating the state decoupling factor to distinguish between the mechanical fluctuation of the gas source and the chemical decay of the adsorbent; the regeneration clamping logic is responsible for comparing the residual desorption pressure with the threshold to ensure the completeness of physical exhaust; and the structural health diagnosis logic identifies bed pulverization or densification faults by monitoring the slope of the pressure relief flow resistance characteristic.

[0038] like Figure 2 As shown, the horizontal axis represents desorption time in seconds, and the vertical axis represents residual desorption pressure in MPa. The solid line depicts the rapid decay trend of residual pressure under normal operating conditions, indicating smooth gas discharge without additional flow resistance. The dashed line depicts the hysteretic decay of residual pressure under pulverized conditions, showing a higher pressure retention value at the same time point. This difference in flow resistance characteristics caused by the slower decompression rate constitutes the physical basis for the adaptive control center to determine whether the adsorbent particles are pulverized or the flow channel is blocked. Figure 3 As shown, the system's physical topology adopts a dual-tower parallel structure. The air inlet is connected via pipeline to a fluid control valve group containing an inlet valve and an outlet valve, which in turn connects to adsorption towers A and B, which are respectively filled with molecular sieve beds. A pressure sensor is installed at the top product gas outlet of each adsorption tower. and These two sensors are connected to the adaptive control center via signal lines, forming a closed loop for fluid impedance characteristic identification and adaptive control for capacity locking, regeneration clamping, and dual-zone decoupling strategies. This drives the intake and exhaust valves below to open and close as needed, and the equalizing valve connected between the two towers to perform potential energy balancing operations, ultimately converging to output product oxygen.

[0039] Example 4: This example addresses the state decoupling factor in the dual-domain decoupling logic of fluid and adsorption kinetics. And the potential problems in setting the judgment threshold, clarifying the state decoupling factor. The physical meaning and mathematical construction logic, such as the specific implementation methods, ,in The average boost rate in the flow resistance-dominated region, The average pressure rise rate represents the adsorption-dominant region. The pressure rise from the inception point to 30% of the operating pressure in the flow resistance-dominant region corresponds to the initial stage of the gas-filled bed voids. At this point, adsorption resistance is relatively low, and the pressure rise is mainly driven by the gas source flow rate. The pressure rise from 70% to 90% of the operating pressure in the adsorption-dominant region corresponds to a stage with higher bed pressure and intense adsorption competition. At this point, the pressure rise rate is mainly constrained by the internal diffusion resistance of the molecular sieve and the adsorption equilibrium rate. Therefore... Essentially, it characterizes the ratio of external fluid thrust to internal adsorption resistance; secondly, it explains the setting principle and adaptive logic of the chemical attenuation threshold, which is designed to distinguish between those caused by gas source fluctuations. and Synchronous changes, and those caused by adsorbent aging Based on statistical analysis of a large amount of experimental data, the asynchronous changes in the gas source flow rate, due to the continuity of fluid mechanics, cause an overall shift in the pressurization rate throughout the entire pressurization process. and It decreases or increases in a directly proportional relationship. The value remains relatively constant, and fluctuations are usually maintained within the baseline value. Within this range, when molecular sieves undergo chemical aging, such as moisture absorption or poisoning, their adsorption capacity and rate decrease, leading to a weakening of the gas phagocytosis effect in the dominant adsorption region, manifesting as... The relative increase means that the pressure rises faster at the end of the adsorption period, while Less affected, this will lead to The value deviates from the benchmark and shows a monotonically decreasing trend.

[0040] Based on the above mechanism, this embodiment constructs the following parameter calibration and threshold setting procedure: Step 1, benchmark Data acquisition: During the initial system operation or the stable operation phase after replacing the adsorbent, data are continuously collected. Each cycle is as follows The pressure data is used to calculate the pressure for each cycle. and The average of the ratios is taken as the baseline state decoupling factor. The second step is to determine the chemical decay threshold. Settings: Settings ,in The aging sensitivity coefficient is recommended to be between 0.8 and 0.9. The selection of this coefficient is based on engineering trade-offs: if... If the value is too close to 1, it may lead to misjudgment due to transient disturbances in the gas source, such as power grid interruptions; if If the value is too small, it may lead to a delay in the detection of early aging. In a typical embodiment, a value of [missing value] is taken. The third step is real-time decision-making logic: During subsequent operations, the current cycle's... ,like And continue Each cycle is as follows If the molecular sieve exhibits chemical aging, a capacity-locking strategy is triggered to shorten the adsorption time; otherwise, if... Decline but If the above procedure is followed, it is determined to be a gas source failure. Through the above procedure, this embodiment concretizes the abstract decoupling logic into quantifiable and reproducible operation steps and parameter setting basis, avoiding technical problems about how to determine the threshold and how to distinguish the fault type.

[0041] Example 5: This example addresses the potential differences in physical properties between different batches of molecular sieve raw materials and the systematic impact of different altitude installation environments on sensor readings. It establishes a set of on-site pre-deployment calibration and engineering commissioning procedures. Since the bulk density and adsorption coefficient of the molecular sieve fluctuate with production batches, and the zero point and range of the pressure transmitter are affected by atmospheric pressure and ambient temperature, directly using preset fixed parameters may lead to control deviations. Therefore, before the system is put into operation, the following standardized initialization process must be performed: Static environmental parameter calibration is performed. With the system powered off and emptied, the logic control unit reads the original voltage signal of the pressure transmitter, calibrates it to the current local atmospheric pressure, and records the ambient temperature as the reference temperature. The air compressor is started to pressurize the adsorption tower without opening the exhaust valve until the pressure inside the tower reaches the opening pressure of the mechanical safety valve. This is used to calibrate the full-scale reading of the pressure sensor and construct a pressure-voltage mapping table. Next, dynamic adsorption characteristic self-learning is performed. During the first 20 cycles of the system's initial load operation, the logic control unit temporarily disables the adaptive adjustment function and only executes a fixed, conservative timing sequence. During this period, the system records the adsorption tower's pressure from the initial pressure point in real time. Rising to work pressure The system generates a pressurization curve and calculates the average pressurization time and average pressurization rate over these 20 cycles. The system then sets the average pressurization time as the initial reference adsorption time. The average boost rate is used as the calculation state decoupling factor. The denominator is based on the standard.

[0042] Finally, a boundary condition pressure test was performed, artificially simulating a gas source failure. By adjusting the intake valve opening to reduce the intake airflow rate to 80% of the rated value, the logic control unit was observed to see if it could correctly identify the pressure rise rate in the flow resistance-dominated region. Decrease, and state decoupling factor The system maintains a constant value; if no misjudgment is triggered, the current control parameters are locked; if a misjudgment is triggered, the aging sensitivity coefficient is automatically fine-tuned. Until the system no longer falsely reports aging faults under flow rate fluctuations, ensuring that the control logic of each device has been adapted and converged for specific hardware tolerances and environmental conditions before delivery, the adaptive control center performs parameter calibration. The calibration procedure quantifies the pressure rise rate characteristics of the adsorption bed during the first system run; during the calibration phase, the logic control unit records and calculates the baseline operating pressure. Average charging rate By adjusting the opening of the intake valve, it generates The controlled flow rate disturbance is collected in real time by the system, which also collects the charging rate under the disturbance conditions. ;calculate and The ratio, with its maximum deviation within the flow resistance-dominated region, is taken as the state decoupling factor. The baseline threshold ;this The system includes quantitative compensation for the impact of gas source fluctuations, enabling... The value only responds to changes in flow resistance caused by the chemical decay of the molecular sieve, avoiding misjudgments caused by mechanical fluctuations in the gas source; capacity lock-in deviation threshold. The value, determined based on a technical trade-off, is directly related to the system's residual nitrogen contamination rate and the risk of adsorption front penetration. For example, the system under standard operating conditions ( , Statistical analysis of the gas production purity-adsorption time distribution curves obtained from 1000 cycles determined the... The deviation value corresponds to the first breakthrough of the adsorption front, but the oxygen purity of the product does not fall below the lower limit of the medical standard. The safety margin is determined by objective measurements based on system operating data.

[0043] In the equalization step, the effective mass transfer flux threshold Ensure that the pressure equalization process is precisely cut off at the point of maximum mass transfer efficiency to avoid nitrogen contamination of the product gas in the low-pressure side tower; Calibration follows the reverse detection procedure for residual oxygen recovery rate, requiring the control center to perform a pressure equalization step after the system is running stably. Pressure equalization should continue once the preset nominal duration has been reached. Real-time monitoring of nitrogen content in residual gas from the low-pressure side adsorption tower; recording the instantaneous pressure difference decay rate at this time. and with Value multiplied by safety factor As Final setting value The safety factor is used to compensate for the nonlinear error of the pressure transmitter, so that... The residual nitrogen content corresponding to the cutoff point is no higher than The system's state; the collaborative logic for fluid impedance fingerprint capacity locking, regeneration clamping, and precise voltage equalization cutoff is implemented in the system controller using a high-real-time, low-latency embedded operating system. The system is configured with a sampling frequency of no less than... The pressure transmitter captures characteristic changes on the pressurization and depressurization curves.

[0044] Example 6: This example addresses the adaptive correction of control parameter boundary conditions in the original document. It establishes a standardized online adaptive parameter fine-tuning procedure for system deployment, performing online dynamic verification of baseline parameters. After the system enters a stable operating state, a boundary condition test is automatically triggered periodically, such as every 1000 hours of operation. The system artificially introduces a known-amplitude intake flow rate disturbance, such as a 10% decrease in flow rate, by fine-tuning the intake valve opening, and continuously monitors the average pressure rise rate in the flow resistance-dominated region. State decoupling factor The response, if under this controlled disturbance, the system calculates... If the value fluctuation is less than the preset safety threshold, such as 2%, then the current aging sensitivity coefficient is determined. The settings are reasonable and should remain unchanged.

[0045] Secondly, an adaptive correction of the aging sensitivity coefficient is performed. If, during the above verification process, If the fluctuation range of the value exceeds the safety threshold, it indicates that the current control model is insufficient to suppress gas source fluctuations and there is a risk of false alarms. At this time, the system automatically starts the correction algorithm to gradually reduce the aging sensitivity coefficient in steps of 0.01. The flow rate perturbation test described above is repeated, and this iterative process continues until... The fluctuation range of the value converges to within the safe threshold or Once the value reaches a preset lower limit, such as 0.8, a new optimal value is determined. The system updates the value to non-volatile memory as a control baseline for subsequent operation; finally, it executes fault self-healing logic under extreme conditions, when the system detects... A sharp decline, for example, a drop of more than 30% and When the value fluctuates abnormally, the system automatically enters the fault self-healing mode. In this mode, the system temporarily disables the capacity lock strategy and executes a preset conservative fixed time sequence, such as shortening the adsorption time to 20 seconds, in order to prioritize the basic oxygen supply. At the same time, the system records the pressure waveform data during the abnormal period and uses this data to reverse-calibrate the flow resistance model parameters after the gas source returns to normal, thereby improving the system's stability in dealing with similar extreme conditions in the future.

[0046] 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.

[0047] 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. A molecular sieve separation system for medical oxygen production, characterized by, The application relates to an air separation system, comprising: an adsorption separation group, comprising double-tower adsorption beds filled with zeolite molecular sieve, the adsorption beds alternately performing pressure swing adsorption cycles to separate oxygen from air; a fluid control valve group for regulating the path of gas into and out of the adsorption separation group; a pressure monitoring unit arranged in the adsorption separation group for collecting internal pressure signals of the adsorption beds; an adaptive control center connected to the fluid control valve group and the pressure monitoring unit; the adaptive control center is used to perform a capacity locking and regeneration clamping strategy, which comprises: during the adsorption pressure charging stage of the adsorption beds, the actual charging time required for the internal pressure signal to rise from a first preset pressure value to a second preset pressure value is monitored in real time; the deviation value of the actual charging time from a pre-stored reference adsorption time is calculated; when the deviation value shows that the actual charging time is shorter than the reference adsorption time and the deviation value exceeds a preset threshold value, a primary switching instruction is generated; at the same time when the primary switching instruction is generated, the real-time residual desorption pressure of another adsorption bed in the regeneration stage is obtained, and the real-time residual desorption pressure is compared with a preset regeneration end pressure threshold value; when the real-time residual desorption pressure is lower than the regeneration end pressure threshold value, a final step switching instruction is output to drive the fluid control valve group to terminate the current adsorption pressure charging stage and start the regeneration stage; if the real-time residual desorption pressure is higher than the regeneration end pressure threshold value, the primary switching instruction is shielded and the current fluid state is maintained until the real-time residual desorption pressure meets the regeneration end pressure threshold value; The adaptive control center is further configured to perform a fluid and adsorption kinetics dual-zone decoupling logic: dividing the adsorption pressure charging stage into a flow resistance dominant zone in a low pressure section and an adsorption dominant zone in a high pressure stabilization section; calculating a first pressure rising rate of the internal pressure signal in the flow resistance dominant zone and a second pressure rising rate of the internal pressure signal in the adsorption dominant zone; and calculating a state decoupling factor for orthogonalizing the gas source mechanical fluctuation and the adsorbent chemical attenuation using the following formula : wherein, is the first pressure rising rate, is the second pressure rising rate; and the adaptive control center is configured to perform a capacity locking and regeneration clamping strategy to adjust the cycle period when the state decoupling factor is monitored to have a variation amplitude relative to a reference value exceeding a preset chemical attenuation threshold; and to maintain the current cycle period unchanged and generate a gas source abnormal signal when the first pressure rising rate is monitored to decrease and the state decoupling factor is maintained within a preset mechanical fluctuation range. the adaptive control center is also used to perform bed structure health degree diagnosis logic: during the regeneration desorption stage of the adsorption beds, the pressure relief response curve of the internal pressure signal with time is monitored; the flow resistance characteristic slope of the pressure relief response curve is extracted and compared with a pre-set standard porosity flow resistance model; when the flow resistance characteristic slope shows that the pressure relief rate is lower than the standard value and at the same time the actual charging time of the adsorption pressure charging stage is shorter than the reference adsorption time, it is determined that physical structure densification or pulverization occurs in the adsorption bed; in response to the determination, the adaptive control center generates a structural fault alarm and locks the current cycle period adjustment strategy; a flow resistance dominant interval is defined as a pressure range in which the internal pressure signal rises from a pressure starting point to 30% of a working pressure; an adsorption dominant interval is defined as a pressure range in which the internal pressure signal rises from 70% to 90% of the working pressure.

2. The molecular sieve separation system for medical oxygen production according to claim 1, characterized in that, the adaptive control center is also used to perform an equalization potential energy adaptive truncation logic: during an equalization stage of performing gas pressure balance operation between two adsorption beds of the adsorption separation group, the instantaneous pressure difference between the two adsorption beds and the time decay rate thereof are calculated in real time; the time decay rate is compared with a preset effective mass transfer flux threshold value; when the time decay rate drops below the effective mass transfer flux threshold value, an instruction is immediately generated to terminate the equalization stage regardless of whether a preset time length of the current equalization step is exhausted.

3. The molecular sieve separation system for medical oxygen production of claim 1, wherein, The reference adsorption duration is a dynamic parameter automatically updated by the adaptive control center based on the optimal adsorption efficiency condition in the system historical operation data; the adaptive control center is also used to execute the environmental temperature trend compensation logic, when the actual charging duration of continuous multiple cycle periods is longer than the reference adsorption duration, the preset adsorption time of the subsequent cycle period is automatically extended.

4. The molecular sieve separation system for medical oxygen production of claim 1, wherein, When the adaptive control center executes the maintenance of the current fluid state, the adsorption bed layer currently performing adsorption is controlled to enter the pressure maintaining hovering state, and the adsorption bed layer currently performing regeneration is controlled to maintain the open state of the exhaust valve until the real-time residual desorption pressure drops below the regeneration end point pressure threshold, the shielding is released and the final step sequence switching instruction is executed.

5. The molecular sieve separation system for medical oxygen production of claim 1, wherein, The fluid control valve group includes an air inlet valve, an exhaust valve and an equalizing valve; the adaptive control center executes the pressure swing adsorption cycle by adjusting the opening and closing time sequence of the air inlet valve and the exhaust valve; the pressure monitoring unit is a pressure transmitter installed at the product gas outlet end of the adsorption bed layer, which is used to collect the bed top pressure change data representing the adsorption front movement characteristics.

6. The molecular sieve separation system for medical oxygen production of claim 1, wherein, The adaptive control center is configured with a fault mode classification logic, which takes the actual charging duration becoming shorter as the first level criterion, and takes the flow resistance characteristic slope as the second level criterion: if the second level criterion shows that the pressure relief rate is normal, it is classified as a chemical aging fault and triggers the cycle period shortening strategy; If the second level criterion shows that the pressure relief rate slows down, it is classified as a physical pulverization fault and triggers a shutdown maintenance alarm.

7. The molecular sieve separation system for medical oxygen production of claim 1, wherein, The adsorption separation group adopts a double-tower parallel structure, the adaptive control center independently monitors the pressure characteristics of each adsorption tower and independently establishes the reference adsorption duration of each adsorption tower, compensating for the adsorption performance imbalance between the two adsorption towers due to the difference in packing density or the difference in valve response delay.

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