High-precision oxygen injection system self-adaptive to environment variables and use method of high-precision oxygen injection system

Abstract

The invention provides a self-adaptive environment variable high-precision oxygen injection system and a use method thereof, which can improve the control precision, response speed and stability of the oxygen injection system in a dynamic environment, and comprises a gas source processing unit, a graded injection unit, an environment sensing unit and an intelligent control unit, the graded injection unit is connected to the output end of the gas source processing unit, and the graded injection unit is provided with a large-flow main gas path and a small-flow precise adjustment gas path which are arranged in parallel; the environment sensing unit is at least arranged at a stable section and a test section of the closed-loop fluid equipment; the intelligent control unit is provided with a feedforward control module, and the total oxygen molecule demand amount is calculated through a corrected gas state equation based on the equipment total pressure, total temperature parameters and liquid nitrogen injection data which are obtained in real time; the closed-loop compensation module acquires monitoring data of the environment sensing unit, and compensates a feed-forward control residual error by adopting an over-damping PID (Proportion Integration Differentiation) algorithm; the accompanying injection module responds to the liquid nitrogen injection signal to control the large-flow main gas circuit and execute hedging control.

Description

Technical Field

[0001] The present invention relates to the field of gas injection control technology, and specifically to a high-precision oxygen injection system suitable for closed-loop fluid system test environments and capable of adapting to environmental variables, and a method for using the system. The system is particularly suitable for scenarios such as aerospace testing and industrial gas precision control. Background Art

[0002] Traditional oxygen injection systems have the following problems in dynamic environments (such as closed-loop fluid system testing):

[0003] Poor environmental adaptability: Unable to perceive pressure, temperature, and liquid nitrogen injection disturbances in real time. In particular, traditional systems cannot predict the dilution effect of liquid nitrogen injection on oxygen concentration in real time, resulting in compensation delays (especially when the liquid nitrogen flow rate suddenly increases) and large oxygen concentration control errors (usually >±10%).

[0004] Low flow regulation accuracy: A single gas path is difficult to cover a wide range of flow requirements (such as 0.1-1400Nm 3 / h), small flow section is easily affected by valve nonlinearity;

[0005] Response lag: Oxygen compensation is delayed (>5 seconds) during liquid nitrogen injection, which can easily cause oxygen concentration overshoot;

[0006] High safety risk: lack of multi-stage pressure and oxygen concentration interlock protection, and insufficient system stability. Summary of the Invention

[0007] The purpose of the present invention is to provide a high-precision oxygen injection system that is adaptive to environmental variables and a method of using the system, which adopts multi-module collaborative control and intelligent algorithm optimization to effectively solve the above-mentioned technical bottlenecks.

[0008] The embodiment of the present invention is achieved as follows:

[0009] A high-precision oxygen injection system that is adaptive to environmental variables, comprising:

[0010] Gas source processing unit, including dew point detector, dual gas source switching mechanism and pressure pretreatment module;

[0011] The graded injection unit is connected to the output end of the gas source processing unit. The graded injection unit has a large-flow main gas circuit and a small-flow precision regulating gas circuit arranged in parallel. The small-flow gas circuit includes at least three independently controllable regulating branches.

[0012] An environmental sensing unit, which integrates a pressure sensor, a temperature sensor, an oxygen analyzer, and a liquid nitrogen injection monitoring module. The environmental sensing unit is provided at least at the rear end of the stable section and the rear end of the test section of the closed-loop fluid equipment.

[0013] Intelligent control unit, equipped with:

[0014] The feedforward control module calculates the total oxygen molecular demand based on the real-time acquired equipment total pressure, total temperature parameters, and liquid nitrogen injection data through the gas state equation combined with the correction equation or simulation model value;

[0015] The closed-loop compensation module obtains the monitoring data of the environmental sensing unit, uses the over-damped PID algorithm to compensate for the feedforward control residual, and controls the small flow rate to perform precise compensation;

[0016] Accompanying the injection module, it responds to the liquid nitrogen injection signal to control the large flow main gas line and perform hedging control;

[0017] Safety interlock unit, including emergency quick-cut valve group and overpressure relief device.

[0018] In a preferred embodiment of the present invention, the feedforward control module performs:

[0019] Calculate the total number of moles of gas in the device n according to PV=nRT;

[0020] Calculate the required number of oxygen molecules Δn based on the target oxygen content ppm value obtained by the environmental sensing unit = (n × ppm target) / (10^6 - ppm target);

[0021] Generate feedforward injection command, control injection amount = K × Δn, where K is an adjustable coefficient of 0.8-0.95;

[0022] The closed-loop compensation module is started after the injection is completed.

[0023] In a preferred embodiment of the present invention, the feedforward control module and the closed-loop compensation module have:

[0024] In the dual-mode regulation mechanism, a parameter set with a proportional coefficient P∈[0.5,1.5] and an integral time Ti≥30s is adopted in the high flow stage;

[0025] In the low flow stage, the parameter group is switched to P∈[0.1,0.3], Ti∈[60,120s];

[0026] The differential action is limited to D≤0.05Ti.

[0027] In a preferred embodiment of the present invention, the accompanying injection module comprises:

[0028] Liquid nitrogen flow prediction submodule obtains liquid nitrogen valve position signals in real time through the Modbus protocol;

[0029] The dynamic compensation algorithm submodule establishes the transfer function between the liquid nitrogen injection amount Q_N2(t) and the oxygen compensation amount ΔQ_O2(t):

[0030] ΔQ_O2(t)=α∫Q_N2(t)dt+βdQ_N2(t) / dt,

[0031] Among them, α=0.78±0.05, β=2.3±0.2;

[0032] The actuator starts the pre-compensation injection 2-5 seconds before the liquid nitrogen is injected.

[0033] In a preferred embodiment of the present invention, the above-mentioned graded injection unit includes:

[0034] The large flow main gas line is equipped with a DN80 pipeline and a combination valve consisting of the first pneumatic regulating valve, the first vortex flowmeter, and the first pneumatic valve. The flow range is 800-1400Nm 3 / h;

[0035] The small flow precision regulating gas circuit is equipped with three parallel branches, which are respectively configured as follows:

[0036] First branch: DN32 pipeline with second pneumatic regulating valve, 0.1% accuracy mass flow meter and second pneumatic valve, flow range 10-50Nm 3 / h;

[0037] Second branch: DN20 pipeline equipped with piezoelectric regulating valve, first flow control valve with accuracy of ±1% FS, flow range of 5-20Nm 3 / h;

[0038] Third branch: DN10 pipeline with stepper motor driven needle valve, second flow control valve with accuracy of ±0.5% FS, flow range of 0.1-5Nm 3 / h.

[0039] In a preferred embodiment of the present invention, the safety interlock unit comprises:

[0040] Three-stage pressure protection mechanism: the first stage triggers the alarm at 1.2MPa, the second stage activates the quick-cut valve at 1.3MPa, and the third stage opens the safety valve at 1.5MPa;

[0041] Oxygen concentration dual threshold protection: When the oxygen content ppm value in the equipment exceeds the set value by 20%, a level 1 alarm is triggered, and when it exceeds 50%, an emergency purge is performed.

[0042] In a preferred embodiment of the present invention, the intelligent control unit is further configured with:

[0043] The equipment volume self-learning module reversely infers the actual volume value V'=V+ΔV through multiple injection test data;

[0044] The dynamic equation correction module expands the ideal gas equation to:

[0045] (P+a(n / V)^2)(V-nb)=nRT, where a and b are van der Waals correction coefficients.

[0046] In a preferred embodiment of the present invention, the above-mentioned environment sensing unit further includes:

[0047] Redundant temperature detection array, with at least 5 groups of PT100 sensors arranged along the axis from the stable section to the test section of the closed-loop fluid equipment;

[0048] The pressure fluctuation compensation module uses a sliding time window algorithm to calculate the dynamic average pressure value. The pressure data processing uses a sliding time window algorithm to take the weighted average of the last 30 seconds of data:

[0049] P_avg=Σ(w_i×P_i) / Σw_i, where w_i=1-0.03×(30-t_i).

[0050] A method for using a high-precision oxygen injection system that is adaptive to environmental variables comprises the following steps:

[0051] The environmental sensing unit collects data from the pressure sensor, temperature sensor and liquid nitrogen injection monitoring module in the closed-loop fluid equipment and calculates the total amount of oxygen molecules required;

[0052] The feedforward control module calculates the total moles of gas using PV=nRT based on real-time total pressure, total temperature, and liquid nitrogen data. It also calculates the total oxygen molecule demand based on the target ppm value and generates a feedforward injection command using a coefficient of 0.8-0.95. The command is then transmitted to the accompanying injection module to control the high-flow main gas valves to execute accompanying injection.

[0053] Perform closed-loop compensation: Use the overdamped PID algorithm to compensate for the feedforward residual. Use the parameter group P∈[0.5,1.5], Ti≥30s in the high flow stage, and switch to the parameter group P∈[0.1,0.3], Ti∈[60,120s] in the low flow stage.

[0054] When the required flow rate is 30-50Nm 3 / h, the first branch mass flow meter and the second branch combination valve are used in combination for regulation;

[0055] When the required flow rate is 10-30Nm 3 / h, the combined valves of the first branch and the third branch are used for regulation;

[0056] When the required flow rate is 5-10Nm 3 / h, the second branch and the third branch combined valve are used for regulation;

[0057] When the required flow rate is less than 5Nm 3 / h, the third branch stepper motor needle valve and high-precision second flow control valve are activated for fine adjustment;

[0058] Flow overlap control is performed when branches are switched to ensure that the total flow fluctuation is <±0.5%.

[0059] In a preferred embodiment of the present invention, the feedforward control step specifically includes:

[0060] Obtain the current pressure P and temperature T, and calculate the corrected volume according to V'=V+ΔV, where ΔV is obtained by reverse calculation through multiple injection tests;

[0061] Apply the modified gas equation (P + a(n / V)^2)(V-nb) = nRT to calculate the actual total number of moles of gas, n;

[0062] Calculate the required number of oxygen molecules Δn = (n × ppm target) / (10^6 - ppm target);

[0063] Generate feedforward injection amount = K × Δn, where K = 0.8-0.95;

[0064] After completing the feedforward injection, start the closed-loop compensation;

[0065] During the injection step, the dynamic compensation coefficients α and β are corrected in real time according to the ambient temperature: when 220K<T<334K, α=0.78×(1+0.002(T-273)); when 105K<T≤220K, β=2.3×(1-0.0015(T-273)).

[0066] The beneficial effects of the embodiments of the present invention are:

[0067] 1. Dynamic perception and precise control of environmental parameters: Utilizing multi-source data fusion and integrating pressure, temperature, and liquid nitrogen injection monitoring modules, the system achieves real-time perception of environmental variables within the closed-loop fluid system, ensuring dynamic adaptability in calculating the total amount of oxygen molecules required and improving error compensation response speed by over 30%. A volumetric self-compensation mechanism, using a modified gas equation (a variant of the van der Waals equation) and a volumetric self-learning algorithm (V' = V + ΔV), eliminates the impact of equipment volume errors on molar number calculations, improving total oxygen content prediction accuracy to ±0.8%.

[0068] 2. Dual-mode collaborative control improves response efficiency: Adopting feedforward-feedback closed-loop collaboration: Feedforward control quickly generates injection instructions (K=0.8-0.95) based on real-time parameters (P, T, liquid nitrogen), and closed-loop compensation eliminates residuals through the over-damped PID algorithm (parameter segment switching). The overall control response time is shortened by 40%, and the steady-state error is <±0.3%; temperature adaptive dynamic compensation is adopted, accompanied by dynamic correction coefficients α and β in the injection (α=0.78×(1+0.002ΔT), β=2.3×(1-0.0015ΔT)), which adapt to the wide temperature range of 105K~334K and improve the compensation accuracy by 25%.

[0069] 3. Hierarchical dynamic adaptation to achieve wide-range precision adjustment: using multi-branch intelligent combination: 30-50Nm 3 / h: The first branch (mass flow meter) + the second branch (piezoelectric valve) combination takes into account the flow range and response speed; 10-30Nm 3 / h: The first branch + the third branch (stepper motor needle valve) work together to achieve a smooth transition between medium and low flow rates; 5-10Nm 3 / h: The second branch + the third branch combination reduces the nonlinear error of small flow; <5Nm 3 / h: The third branch needle valve + high-precision MFC fine-tuning, accuracy of ±0.1%. At the same time, flow overlap control technology is adopted, and a flow superposition transition strategy is adopted when switching branches, suppressing the total flow fluctuation to <±0.5%, avoiding step interference.

[0070] 4. Enhanced safety and stability: Adopting pressure-graded protection: a three-stage interlock with 1.2MPa alarm, 1.3MPa quick-cut valve action, and 1.5MPa relief reduces the system overpressure risk by 90%. Adopting dual-threshold management for oxygen concentration, with an early warning when the threshold exceeds 20% and an emergency purge at 50%, it prevents the risk of explosion in oxygen-rich environments. Adopting anti-saturation PID mode: When the pressure fluctuation is greater than 0.5% / s, integral saturation is automatically suppressed (I_new = I_old × exp(-Δt / τ)) to avoid control instability.

[0071] 5. Intelligence and long-term reliability: The injection volume is optimized using volumetric self-learning: ΔV = Σ(Δn measured - Δn theoretical) / (Δn theoretical / V) × 0.2 is inferred from injection test data, dynamically correcting system volume deviations and improving long-term stability by 50%. Redundant temperature detection: 5 groups of PT100 sensor arrays + sliding time window algorithm (P_avg = Σ(w_i × P_i) / Σw_i) achieve data reliability of 99.9%.

[0072] 6. Economic benefits and applicability: Energy consumption optimization: pre-adjustment design with feedforward injection coefficient K = 0.8-0.95 reduces closed-loop compensation energy consumption by 15-20%; wide working condition compatibility: covering 0.1-1400Nm 3 / h flow range, suitable for closed-loop fluid system testing, semiconductor manufacturing and other scenarios; reduced maintenance costs: the graded branch design extends the service life of precision valves (such as DN10 needle valves) by more than 30%.

[0073] In summary, the present invention realizes the high precision (±0.3%) and wide range (0.1-1400Nm) of the oxygen injection system in complex environments through the full chain coordination of environmental perception-feedforward prediction-closed-loop feedback compensation-graded execution-safety protection. 3 / h), fast response (<1s) and high reliability (failure rate <0.01%), and is particularly suitable for high-end fields such as aerospace closed-loop fluid system testing and semiconductor process gas control. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0075] Figure 1 is a structural block diagram of a high-precision oxygen injection system according to an embodiment of the present invention;

[0076] Figure 2 This is a control block diagram of an intelligent control unit according to an embodiment of the present invention;

[0077] Figure 3 A flow chart of a method for using a high-precision oxygen injection system that is adaptive to environmental variables according to an embodiment of the present invention;

[0078] Icons: gas source processing unit 105; graded injection unit 120; large-flow main gas circuit 121; small-flow precision adjustment gas circuit 122; environmental sensing unit 130; intelligent control unit 140; feedforward control module 141; closed-loop compensation module 142; accompanying injection module 143; safety interlock unit 144. DETAILED DESCRIPTION

[0079] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0080] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0081] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0082] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art.

[0083] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner.In the following description, many specific details are provided so as to provide a full understanding of the embodiments of the present application. However, it will be appreciated by those skilled in the art that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps etc. can be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0084] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically separate entities. That is, these functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0085] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0086] First embodiment

[0087] See Figure 1 and Figure 2 This embodiment provides a high-precision oxygen injection system that is adaptive to environmental variables, comprising:

[0088] The gas source processing unit 105 includes a dew point detector, a dual gas source switching mechanism, and a pressure preprocessing module. The pressure preprocessing module is used to overcome the problem of a large working pressure span. It includes an automatic pressure stabilizing valve and a diaphragm pneumatic regulating valve connected in sequence.

[0089] The automatic pressure-stabilizing valve stabilizes the pressure differential across the gas line based on changes in the total pressure of the closed-loop fluid equipment, thereby stabilizing the airflow rate. Controlling and achieving a stable pressure differential is the first step in controlling gas flow. Secondly, to further enhance control over gas flow within the pipeline, the pressure pretreatment module also adds a diaphragm-type pneumatic regulating valve to the pipeline. This valve features a fast control response and is used to actively regulate gas flow within the pipeline, improving the accuracy of oxygen injection and maintaining a constant pressure differential of 0.4 MPa.

[0090] The graded injection unit 120 is connected to the output end of the gas source processing unit 105. The graded injection unit 120 has a large flow main gas circuit 121 and a small flow precision regulating gas circuit 122 arranged in parallel. The small flow gas circuit includes at least three independently controllable regulating branches;

[0091] Environmental sensing unit 130. In this embodiment, even though an automatic pressure-stabilizing valve and a thin-film pneumatic regulating valve are designed to precisely control the gas flow within the pipeline, the absolute value of the pressure within the pipeline is still variable, which will still affect the air density within the pipeline and the flow rate of injected oxygen molecules. In this embodiment, an environmental sensing unit 130 is also designed, which includes an integrated pressure sensor, a temperature sensor, an oxygen analyzer, and a liquid nitrogen injection monitoring module. The environmental sensing unit 130 is installed at least at the rear end of the stable section and the rear end of the test section of the closed-loop fluid equipment.

[0092] The intelligent control unit 140 is configured with:

[0093] The feedforward control module 141 calculates the total oxygen molecular demand based on the real-time acquired equipment total pressure, total temperature parameters, and liquid nitrogen injection data through the gas state equation combined with the correction equation or simulation model value;

[0094] The closed-loop compensation module 142 obtains the monitoring data of the environmental sensing unit 130, uses the over-damped PID algorithm to compensate the feedforward control residual, and controls the small flow airflow to perform precise compensation;

[0095] The accompanying injection module 143 controls the large flow main gas path 121 and performs hedging control in response to the liquid nitrogen injection signal;

[0096] The safety interlock unit 144 includes an emergency quick-cut valve group and an overpressure relief device.

[0097] In traditional closed-loop fluid systems, the response to random liquid nitrogen injection disturbances is delayed. The core issue lies in the inability of traditional systems to predict the dilution effect of liquid nitrogen injection on oxygen concentration in real time, resulting in delayed compensation (especially during sudden increases in liquid nitrogen flow) and excessive fluctuations in oxygen concentration. This directly leads to the following system flaws: reliance on single feedback control, resulting in insufficient response speed; the lack of a dynamic transfer function between liquid nitrogen flow and oxygen compensation, leading to offset mismatches; and in extreme scenarios (liquid nitrogen flow >1400Nm3 / h), insufficient gas supply capacity and significant compensation lag.

[0098] In response to the above problems, automatic accompanying injection is used in this embodiment to overcome the interference of liquid nitrogen. The main strategy is to read the injection data of liquid nitrogen, such as the liquid nitrogen injection flow rate and the liquid nitrogen injection time length, so as to control the corresponding flow rate and duration of the injection of air. At the same time, through the large-flow main gas path 121, timely response is made to quickly stabilize the problem of excessive fluctuation of oxygen concentration, so as to achieve the function of stabilizing the system ppm value.

[0099] Specifically, the feedforward control module 141 in this embodiment performs the following steps:

[0100] Calculate the total number of moles of gas in the device n according to PV=nRT;

[0101] Calculate the required number of oxygen molecules Δn=(n×ppm target) / (10^6-ppm target) according to the target oxygen content ppm value obtained by the environment sensing unit 130;

[0102] Generate feedforward injection command, control injection amount = K × Δn, where K is an adjustable coefficient of 0.8-0.95;

[0103] The closed loop compensation module 142 is activated after the injection is completed.

[0104] Among them, for the general feedforward control algorithm, this embodiment includes both a feedforward control module 141 and a closed-loop compensation module 142, wherein the closed-loop compensation module 142 adopts PID feedback control to form a closed loop. It can solve the overshoot risk under traditional unidirectional control. For example, traditional PID parameters (critical damping or underdamping) are prone to overshoot (such as overshoot>5%) in a unidirectional injection system and cannot be corrected by reverse operation. This embodiment improves the integral saturation suppression mechanism by adopting an overdamped PID parameter group; improves the feedforward-feedback collaborative strategy, and implements segmented control of the injection volume (such as 80%-95%) to perform dynamic optimization. Specifically, the feedforward control module 141 and the closed-loop compensation module 142 have:

[0105] In the dual-mode regulation mechanism, a parameter set with a proportional coefficient P∈[0.5,1.5] and an integral time Ti≥30s is adopted in the high flow stage;

[0106] In the low flow stage, the parameter group is switched to P∈[0.1,0.3], Ti∈[60,120s];

[0107] The differential action is limited to D≤0.05Ti.

[0108] During the test operation of the closed-loop fluid equipment, liquid nitrogen may be automatically added to the closed-loop fluid equipment system at any time. The addition of liquid nitrogen will dilute the oxygen content ppm. When performing stable control of the oxygen content ppm, this random interference factor must be considered. In this embodiment, accompanying injection is used to overcome this drawback. The accompanying injection module 143 specifically includes:

[0109] Liquid nitrogen flow prediction submodule obtains liquid nitrogen valve position signals in real time through the Modbus protocol;

[0110] The dynamic compensation algorithm submodule establishes the transfer function between the liquid nitrogen injection amount Q_N2(t) and the oxygen compensation amount ΔQ_O2(t):

[0111] ΔQ_O2(t)=α∫Q_N2(t)dt+βdQ_N2(t) / dt,

[0112] Among them, α=0.78±0.05, β=2.3±0.2;

[0113] The actuator starts the pre-compensation injection 2-5 seconds before the liquid nitrogen is injected to overcome the liquid nitrogen offset lag.

[0114] In this embodiment, a companion injection module 143 (ΔQ_O2=α∫Q_N2dt+βdQ_N2 / dt)+pre-compensation mechanism is adopted, and the hedge response time is ≤2 seconds and the fluctuation is <±1%.

[0115] The wide pressure range of the test conditions will affect the accuracy of controlling the oxygen injection rate. For example, the pressure fluctuation within the closed-loop fluid equipment ranges from 0.1 to 0.4 MPa, while the initial outlet pressure of the air source is 1 MPa. If the piping system connecting the air source and the closed-loop fluid equipment is not pressure-controlled, the pressure difference between the air source and the closed-loop fluid equipment in the pipeline will fluctuate by 0.6 to 0.9 MPa as the test conditions change.

[0116] Since the gas flow rate in the pipeline is proportional to the pressure difference at both ends of the pipeline (refer to the Pitot tube flow rate calculation formula K is the correction parameter, ΔP is the pressure difference, and ρ is the gas density. If the pressure difference between the two ends of the pipeline is a variable, it is difficult to obtain a stable gas flow rate. An unstable gas flow rate will result in an unstable gas flow rate, which is not conducive to controlling the injection accuracy. In this embodiment, a step-by-step injection method is adopted to overcome the above-mentioned drawbacks. The step-by-step injection unit 120 includes:

[0117] The large flow main gas line 121 is equipped with a DN80 pipeline and a combination valve consisting of the first pneumatic regulating valve, the first vortex flowmeter, and the first pneumatic valve. The flow range is 800-1400Nm 3 / h;

[0118] The small flow precision regulating gas circuit 122 is provided with three parallel branches, configured as follows:

[0119] First branch: DN32 pipeline with second pneumatic regulating valve, 0.1% accuracy mass flow meter and second pneumatic valve, flow range 10-50Nm 3 / h;

[0120] Second branch: DN20 pipeline equipped with piezoelectric regulating valve, first flow control valve with accuracy of ±1% FS, flow range of 5-20Nm 3 / h;

[0121] Third branch: DN10 pipeline with stepper motor driven needle valve, second flow control valve with accuracy of ±0.5% FS, flow range of 0.1-5Nm 3 / h.

[0122] In a preferred embodiment of the present invention, the safety interlock unit 144 includes:

[0123] Three-stage pressure protection mechanism: the first stage triggers the alarm at 1.2MPa, the second stage activates the quick-cut valve at 1.3MPa, and the third stage opens the safety valve at 1.5MPa;

[0124] Oxygen concentration dual threshold protection: When the oxygen content ppm value in the equipment exceeds the set value by 20%, a level 1 alarm is triggered, and when it exceeds 50%, an emergency purge is performed.

[0125] The core issue with the gas loss estimation error caused by system pressure relief lies in the traditional model's assumption that the system is closed, ignoring the gas loss during the pressure relief process, which leads to a deviation in the calculation of the total amount of oxygen molecules (error rate >15%). However, the existing system does not integrate a dynamic volume correction algorithm (such as V'=V+ΔV), resulting in the failure of the ideal gas equation (PV=nRT). Furthermore, the system lacks a real-time monitoring module for pressure relief events, making it impossible to synchronously update the total gas volume model. Based on the above shortcomings, the intelligent control unit 140 is also equipped with:

[0126] The equipment volume self-learning module reversely infers the actual volume value V'=V+ΔV through multiple injection test data;

[0127] The dynamic equation correction module expands the ideal gas equation to:

[0128] (P+a(n / V)^2)(V-nb)=nRT, where a and b are van der Waals correction coefficients.

[0129] The dynamically corrected ideal gas calculation method can also overcome the deviation between the traditional ideal gas model and actual operating conditions. Since the traditional ideal gas model does not take into account the intermolecular forces, the volume estimation error (ΔV uncorrected) leads to a feedforward control deviation of >10%.

[0130] In this embodiment, by introducing correction models such as the van der Waals equation and combining them with a volume self-learning mechanism (such as the ΔV back-calculation algorithm), the accuracy of the calculation of the total oxygen molecule demand is improved, and the model has good long-term adaptability.

[0131] In this embodiment, the environment sensing unit 130 further includes:

[0132] Redundant temperature detection array, with at least 5 groups of PT100 sensors arranged along the axis from the stable section to the test section of the closed-loop fluid equipment;

[0133] The pressure fluctuation compensation module uses a sliding time window algorithm to calculate the dynamic average pressure value. The pressure data processing uses a sliding time window algorithm to take the weighted average of the last 30 seconds of data:

[0134] P_avg=Σ(w_i×P_i) / Σw_i, where w_i=1-0.03×(30-t_i).

[0135] In summary, the high-precision oxygen injection system with adaptive environmental variables specifically addresses the technical defects of existing closed-loop fluid systems, significantly improving the control accuracy, response speed and stability of the oxygen injection system in dynamic environments. It is especially suitable for complex scenarios such as high-precision closed-loop fluid system tests.

[0136] Second embodiment

[0137] Based on the first embodiment, this embodiment further explains some key details of its use method. This embodiment provides a method for using a high-precision oxygen injection system that is adaptive to environmental variables, which includes the following steps. Figure 3 :

[0138] The environmental sensing unit 130 collects data from the pressure sensor, temperature sensor and liquid nitrogen injection monitoring module in the closed-loop fluid equipment and calculates the total amount of oxygen molecules required through the feedforward control module;

[0139] Based on the real-time total pressure, total temperature, and liquid nitrogen data, the feedforward control module 141 calculates the current total gas moles using the corrected (P + a(n / V)^2)(V-nb) = nRT, calculates the total oxygen molecular demand based on the target ppm value, generates a feedforward injection command using a coefficient of 0.8-0.95, and transmits it to the accompanying injection module 143 to control the valve components of the high-flow main gas path 121 to perform accompanying injection.

[0140] Perform closed-loop compensation: Use the overdamped PID algorithm to compensate for the feedforward residual. Use the parameter group P∈[0.5,1.5], Ti≥30s in the high flow stage, and switch to the parameter group P∈[0.1,0.3], Ti∈[60,120s] in the low flow stage.

[0141] When the required flow rate is 30-50Nm 3 / h, the first branch mass flow meter and the second branch combination valve are used in combination for regulation;

[0142] When the required flow rate is 10-30Nm 3 / h, the combined valves of the first branch and the third branch are used for regulation;

[0143] When the required flow rate is 5-10Nm 3 / h, the second branch and the third branch combined valve are used for regulation;

[0144] When the required flow rate is less than 5Nm 3 / h, the third branch stepper motor needle valve and high-precision second flow control valve are activated for fine adjustment;

[0145] Flow overlap control is performed when branches are switched to ensure that the total flow fluctuation is <±0.5%.

[0146] In the present embodiment, the oxygen graded injection unit 120 adopts a large-flow main gas circuit 121 and a small-flow precision regulating gas circuit 122 arranged in parallel. The small-flow gas circuit contains at least three independently controllable regulating branches, and each branch is equipped with different pipeline valves to overcome the problem of unstable airflow caused by system pressure fluctuations. The core of the problem is that the change in pipeline pressure difference (0.6-0.9MPa) causes the gas flow rate to fluctuate (reference V=K√(2ΔP / ρ)), and the flow control accuracy decreases (more than ±5%). In this embodiment, by configuring a pressure-stabilizing valve or a dynamic pressure difference control module, the flow rate is significantly reduced by the influence of the working pressure; the use of multiple valves overcomes the problem that the traditional pneumatic regulating valve has insufficient response speed (>1s) and cannot quickly suppress flow fluctuations.

[0147] Because the relationship between ppm and oxygen content in closed-loop fluid systems is nonlinear under varying operating conditions, the core issue lies in existing systems using ppm as a single control variable, ignoring the impact of temperature and pressure variations on the number of oxygen molecules. This results in oxygen injection rates varying by a factor of 10 for the same ppm deviation (e.g., 115kPa / 334K vs. 450kPa / 105K). This, in turn, results in traditional closed-loop fluid systems failing to convert ppm into oxygen mass / molecular number differences, resulting in a disconnect between control strategies and physical quantities. Furthermore, the system lacks a compensation algorithm for temperature and pressure coupling, making it impossible to dynamically correct the control variable.

[0148] To address the above issues, the feedforward control step in this embodiment further modifies the oxygen calculation method and incorporates a temperature-pressure coupling compensation algorithm, which specifically includes:

[0149] Obtain the current pressure P and temperature T, and calculate the corrected volume according to V'=V+ΔV, where ΔV is obtained by reverse calculation through multiple injection tests;

[0150] Apply the modified gas equation (P + a(n / V)^2)(V-nb) = nRT to calculate the actual total number of moles of gas, n;

[0151] Calculate the required number of oxygen molecules Δn = (n × ppm target) / (10^6 - ppm target);

[0152] Generate feedforward injection amount = K × Δn, where K = 0.8-0.95;

[0153] After completing the feedforward injection, start the closed-loop compensation;

[0154] During the injection step, the dynamic compensation coefficients α and β are corrected in real time according to the ambient temperature: when 220K<T<334K, α=0.78×(1+0.002(T-273)); when 105K<T≤220K, β=2.3×(1-0.0015(T-273)).

[0155] At the same time, the feedforward control step also overcomes density errors caused by changes in pipeline pressure. For example, the flowmeters in existing closed-loop fluid equipment do not consider the impact of changes in absolute pressure on gas density, resulting in errors in mass flow calculation (such as a density error of >30% at 0.4MPa). This feedforward control step calculates mass flow rather than traditional volume flow, and integrates a real-time density compensation algorithm to make the calculated oxygen content demand more accurate. During the calculation process, a flow correction module that integrates multiple parameters (P, T) is used for real-time correction.

[0156] Third embodiment

[0157] This embodiment uses the closed-loop fluid system test as an example to illustrate the system operation flow and calculation process:

[0158] Initialization: Start the gas source processing unit 105, switch the dual gas source to a qualified gas source, and pre-treat the pressure to 1.0 MPa;

[0159] Environmental perception: Obtain stable pressure P = 0.95 MPa, T = 300K, and liquid nitrogen injection rate Q_N2 = 200 Nm3 / h;

[0160] Feedforward calculation: Corrected volume V' = 50m3 (ΔV = 0.5m3);

[0161] Calculate the total number of moles n = (P × V') / (RT) = 1950 mol;

[0162] Target oxygen concentration ppm = 5000, Δn = (1950 × 5000) / (10 - 5000) = 9.95 mol;

[0163] Feedforward injection amount = 0.9 × 9.95 = 8.96 mol (corresponding to oxygen flow rate 32.1 Nm3 / h);

[0164] Accompanying injection: start the main gas line 3 seconds before liquid nitrogen injection, compensation amount ΔQ_O2=0.78×200+2.3×20=187.6Nm3 / h;

[0165] Closed-loop compensation: detect residual -0.5%, switch to small flow PID parameters (P = 0.2, Ti = 90s), and adjust the opening of the third branch needle valve to 45%;

[0166] Safety monitoring: The oxygen concentration is stable at 4995ppm, the pressure is 1.05MPa, and the system is in a safe state.

[0167] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the composition and steps of each example according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0168] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or can be electrical, mechanical or other forms of connection.

[0169] The units described as separate components may or may not be physically separated. As a unit, a person of ordinary skill in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0170] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0171] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the existing technology, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes a number of instructions for causing a computer device (which can be a personal computer, server, or grid device, etc.) to perform all or part of the steps of the method described in various embodiments of the present invention.

[0172] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-precision oxygen injection system that is adaptive to environmental variables, characterized in that: include: Gas source processing unit, including dew point detector, dual gas source switching mechanism and pressure pretreatment module; A graded injection unit is connected to the output end of the gas source processing unit, and the graded injection unit has a large-flow main gas circuit and a small-flow precision regulating gas circuit arranged in parallel, and the small-flow gas circuit includes at least three independently controllable regulating branches; An environmental sensing unit, integrating a pressure sensor, a temperature sensor, an oxygen analyzer, and a liquid nitrogen injection monitoring module, wherein the environmental sensing unit is provided at least at the rear end of the stable section and the rear end of the test section of the closed-loop fluid equipment; Intelligent control unit, equipped with: The feedforward control module calculates the total oxygen molecular demand based on the real-time acquired equipment total pressure, total temperature parameters, and liquid nitrogen injection data through the gas state equation combined with the correction equation or simulation model value; a closed-loop compensation module, which obtains the monitoring data of the environmental sensing unit, uses an over-damped PID algorithm to compensate for the feedforward control residual, and controls the small flow airflow to perform precise compensation; An accompanying injection module controls the large-flow main gas path and performs hedging control in response to a liquid nitrogen injection signal; Safety interlock unit, including emergency quick-cut valve group and overpressure relief device.

2. The high-precision oxygen injection system according to claim 1, wherein: The feedforward control module performs: Calculate the total number of moles of gas in the device n according to PV=nRT; Calculate the required number of oxygen molecules Δn based on the target oxygen content ppm value obtained by the environmental sensing unit = (n × ppm target) / (10^6 - ppm target); Generate feedforward injection command, control injection amount = K × Δn, where K is an adjustable coefficient of 0.8-0.95; After the injection is completed, the closed-loop compensation module is started.

3. The high-precision oxygen injection system according to claim 2, wherein: The feedforward control module and the closed-loop compensation module have: In the dual-mode regulation mechanism, a parameter set with a proportional coefficient P∈[0.5,1.5] and an integral time Ti≥30s is adopted in the high flow stage; In the low flow stage, the parameter group is switched to P∈[0.1,0.3], Ti∈[60,120s]; The differential action is limited to D≤0.05Ti.

4. The high-precision oxygen injection system according to claim 1, wherein: The accompanying injection module includes: Liquid nitrogen flow prediction submodule obtains liquid nitrogen valve position signals in real time through the Modbus protocol; The dynamic compensation algorithm submodule establishes the transfer function between the liquid nitrogen injection amount Q_N2(t) and the oxygen compensation amount ΔQ_O2(t): ΔQ_O2(t)=α∫Q_N2(t)dt+βdQ_N2(t) / dt, Among them, α=0.78±0.05, β=2.3±0.2; The actuator starts the pre-compensation injection 2-5 seconds before the liquid nitrogen is injected.

5. The high-precision oxygen injection system according to claim 1, wherein: The graded injection unit comprises: The large flow main gas line is equipped with a DN80 pipeline and a combination valve consisting of the first pneumatic regulating valve, the first vortex flowmeter, and the first pneumatic valve. The flow range is 800-1400Nm 3 / h; The small flow precision regulating gas circuit is equipped with three parallel branches, which are respectively configured as follows: First branch: DN32 pipeline with second pneumatic regulating valve, 0.1% accuracy mass flow meter and second pneumatic valve, flow range 10-50Nm 3 / h; Second branch: DN20 pipeline equipped with piezoelectric regulating valve, first flow control valve with accuracy of ±1% FS, flow range of 5-20Nm 3 / h; Third branch: DN10 pipeline equipped with a stepper motor driven needle valve, a second flow control valve with an accuracy of ±0.5% FS, and a flow range of 0.1-5Nm 3 / h.

6. The high-precision oxygen injection system according to claim 1, wherein: The safety interlock unit comprises: Three-stage pressure protection mechanism: the first stage triggers the alarm at 1.2MPa, the second stage activates the quick-cut valve at 1.3MPa, and the third stage opens the safety valve at 1.5MPa; Oxygen concentration dual threshold protection: When the oxygen content ppm value in the equipment exceeds the set value by 20%, a level 1 alarm is triggered, and when it exceeds 50%, an emergency purge is performed.

7. The high-precision oxygen injection system according to claim 1, wherein: The intelligent control unit is also configured with: The equipment volume self-learning module reversely infers the actual volume value V'=V+ΔV through multiple injection test data; The dynamic equation correction module expands the ideal gas equation to: (P+a(n / V)^2)(V-nb)=nRT, where a and b are van der Waals correction coefficients.

8. The high-precision oxygen injection system according to claim 1, wherein: The environment perception unit further includes: Redundant temperature detection array, with at least 5 groups of PT100 sensors arranged along the axis from the stable section to the test section of the closed-loop fluid equipment; The pressure fluctuation compensation module uses a sliding time window algorithm to calculate the dynamic average pressure value. The pressure data processing uses a sliding time window algorithm to take the weighted average of the last 30 seconds of data: P_avg=Σ(w_i×P_i) / Σw_i, where w_i=1-0.03×(30-t_i).

9. A method for using a high-precision oxygen injection system that is adaptive to environmental variables, characterized in that: The following steps are involved: The environmental sensing unit collects data from the pressure sensor, temperature sensor and liquid nitrogen injection monitoring module in the closed-loop fluid equipment and calculates the total amount of oxygen molecules required; The feedforward control module calculates the total moles of gas using PV=nRT based on real-time total pressure, total temperature, and liquid nitrogen data. It also calculates the total oxygen molecule demand based on the target ppm value and generates a feedforward injection command using a coefficient of 0.8-0.

95. The command is then transmitted to the accompanying injection module to control the high-flow main gas valves to execute accompanying injection. Perform closed-loop compensation: Use the overdamped PID algorithm to compensate for the feedforward residual. Use the parameter group P∈[0.5,1.5], Ti≥30s in the high flow stage, and switch to the parameter group P∈[0.1,0.3], Ti∈[60,120s] in the low flow stage. When the required flow rate is 30-50Nm 3 / h, the first branch mass flow meter and the second branch combination valve are used in combination for regulation; When the required flow rate is 10-30Nm 3 / h, the combined valves of the first branch and the third branch are used for regulation; When the required flow rate is 5-10Nm 3 / h, the second branch and the third branch combined valve are used for regulation; When the required flow rate is less than 5Nm 3 / h, the third branch stepper motor needle valve and high-precision second flow control valve are activated for fine adjustment; Flow overlap control is performed when branches are switched to ensure that the total flow fluctuation is <±0.5%.

10. The method for using the high-precision oxygen injection system capable of self-adapting to environmental variables according to claim 9, characterized in that: The feedforward control step specifically includes: Obtain the current pressure P and temperature T, and calculate the corrected volume according to V'=V+ΔV, where ΔV is obtained by reverse calculation through multiple injection tests; Apply the modified gas equation (P + a(n / V)^2)(V-nb) = nRT to calculate the actual total number of moles of gas, n; Calculate the required number of oxygen molecules Δn = (n × ppm target) / (10^6 - ppm target); Generate feedforward injection amount = K × Δn, where K = 0.8-0.95; After completing the feedforward injection, start the closed-loop compensation; In the accompanying injection step, the dynamic compensation coefficients α and β are corrected in real time according to the ambient temperature: when 220K<T<334K, α=0.78×(1+0.002(T-273)); when 105K<T≤220K, β=2.3×(1-0.0015(T-273)).

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