A load following automatic tracking control method for air separation unit in nonferrous metal smelting

Abstract

The present invention provides a load tracking and automatic control method for an air separation unit in nonferrous metal smelting, relating to the field of computer processing technology. The method comprises the following steps: S01, using a DCS system to detect in real time the flow rate data of oxygen products delivered from the air separation unit. The flow rate data includes: the flow rate of oxygen 1 product detected by FI1511; the flow rate of oxygen 2 product detected by FI1512; the flow rate of oxygen 3 product detected by FI1513; and the flow rate of pressurized nitrogen detected by FI1501; S02, using FSP1294 as the set value for the load control loop FIC1294 of the main raw air compressor, and performing closed-loop regulation of the compressor through the DCS system. This invention achieves precise control of the oxygen product load by real-time monitoring of client oxygen consumption and dynamically matching the raw air supply and key operating parameters of the distillation tower without manual intervention or complex data models, while ensuring the stability of the main distillation system.

Description

Technical Field

[0001] The present invention relates to the field of computer processing technology, in particular to a load following automatic tracking control method for an air separation device for non-ferrous metal smelting. Background Art

[0002] In the nonferrous metal smelting industry, oxygen is a key process gas, and the stability of its supply directly impacts the continuity and production efficiency of the smelting process. Traditional smelting processes typically require the use of multiple gas products, including low-pressure oxygen (oxygen 1), low-pressure oxygen (oxygen 2), medium-pressure oxygen (oxygen 3), and pressurized nitrogen. The consumption load of oxygen 1 exhibits periodic, instantaneous, and random fluctuations, ranging from approximately 10% of rated output. This is significantly different from the large fluctuations in oxygen load in steelmaking. These small-scale random fluctuations place higher demands on the dynamic response capabilities of the supporting air separation unit, requiring real-time adaptive adjustment of the oxygen supply load while ensuring the stable operation of the main distillation tower.

[0003] At present, the oxygen supply control of air separation units in the industry mainly relies on two modes:

[0004] The first is a manual scheduling and coordination mechanism, whereby plant dispatchers manually adjust the oxygen supply target parameters of the air separation unit based on changes in client demand. This approach suffers from lags in response and reliance on manual experience. It is difficult to adapt to the instantaneous and random fluctuations in oxygen load in non-ferrous metal smelting, and manual intervention can easily lead to distillation system instability due to sudden load changes.

[0005] The second is traditional automatic variable load control systems, which typically implement load regulation based on preset rules or big data models. However, these systems are primarily designed for large-scale load fluctuations, such as in steelmaking, and are less adaptable to the small, random fluctuations found in nonferrous metal smelting. Furthermore, systems that rely on big data analysis require complex data acquisition and processing architectures, resulting in high implementation costs and limited integration with process mechanisms. This makes it difficult to ensure real-time and reliable control in scenarios with frequent fluctuations.

[0006] Taking the 66,000 Nm³ / h air separation unit (ASU) supporting Yunnan Copper as an example, it utilizes an internal compression process design, requiring a stable supply of oxygen and nitrogen products at multiple pressure levels. Under traditional control modes, frequent fluctuations in oxygen load can easily lead to imbalances in the reflux ratio of the main distillation column, impacting the purity of the oxygen and nitrogen products and the overall energy efficiency of the unit. Although existing technologies attempt to achieve partial parameter adjustment by optimizing compressor speed or adjusting expander load, they fail to systematically link feed air volume, distillation column operating parameters, and client demand changes at the process mechanism level. This results in limited control accuracy and makes it difficult to achieve fully unmanned operation. Summary of the Invention

[0007] In response to the above technical problems, the technical solution adopted by the present invention is a load following automatic tracking control method for an air separation unit for non-ferrous metal smelting, the method comprising the following steps:

[0008] S01. Detect the flow rate data of oxygen products delivered by the air separation unit in real time through the DCS system. The flow rate data includes:

[0009] Oxygen 1 product flow rate obtained by FI1511 detection;

[0010] Oxygen 2 product flow rate obtained by FI1512 detection;

[0011] Oxygen 3 product flow rate obtained by FI1513 detection;

[0012] The pressure nitrogen flow rate obtained by FI1501 detection;

[0013] S02, using FSP1294 as the set value of the main raw material air compressor load control loop FIC1294, and performing closed-loop regulation of the compressor through the DCS system;

[0014] S03, the APC system calculates the total raw air flow target value FSP1294 based on the oxygen extraction rate formula: oxygen extraction rate = , wherein the total raw air volume is obtained by back calculation by the APC system;

[0015] S04. Arrange TI1616 detection based on the gas-liquid equilibrium temperature point in the sensitive area of ​​the distillation tower, and dynamically compensate and correct FSP1294 through the TIC1616-PID control loop to stabilize TI1616 within the range of -188℃±0.5℃;

[0016] S05. Calculate the boost air flow rate FSP1563 based on 1.25 times the FI1511, calculate the high-pressure air flow rate FSP1536 based on 1.3 times the sum of FI1512, FI1513, and FI1501, and control the heat source flows of the liquid oxygen evaporator heat exchanger and the main heat exchanger respectively through the DCS system;

[0017] S06. When the DCS system detects that any flow meter among FI1511, FI1512, and FI1513 fails, the APC system stops outputting FSP1294 and triggers an alarm, while keeping the FIC1294 at the pre-fault setting value until the fault is resolved.

[0018] Preferably, the dynamic compensation correction step in step S04 includes: converting the TI1616 detection value into thermodynamic temperature and amplifying it by 1000 times, and then inputting it into the TIC1616-PID control module, whose output is limited to ±6000 Nm³ / h;

[0019] The FSP1294 is then corrected in real time through the adder module, and the correction range does not exceed ±5% of the initial value of the FSP1294;

[0020] The normal control range of the TI1616 is -186.5°C to -188.5°C, and the DCS system retains two decimal places of accuracy.

[0021] Preferably, the calculation formula of the boost air flow FSP1563 in step S05 is:

[0022] Oxygen 1 supporting boost air flow setting value: FSP1563=FI1511×1.25;

[0023] The setting value of the high-pressure air flow rate for oxygen 2 product flow, oxygen 3 product flow and pressurized nitrogen flow is: FSP1536=(FI1512+FI1513+FI1501)×1.3;

[0024] Among them, FI1501 is the pressure nitrogen flow rate, the flow ratio of the boosted air to the liquid oxygen evaporator heat exchanger is 1.25:1, and the flow ratio of the high-pressure air to the oxygen 2 product flow rate, the oxygen 3 product flow rate and the pressure nitrogen flow rate is 1.3:1.

[0025] As a preference, the liquid oxygen evaporator safety temperature control step is also included:

[0026] The liquid oxygen temperature TI1563 is detected by the DCS system, and the target temperature TSP1563 is dynamically calculated based on the evaporator pressure PI1563: , where P0 is the atmospheric pressure at the location of the air separation unit;

[0027] The boost air flow FSP1563 is adjusted through the TIC1563 PID control loop to make TI1563 lower than the saturation temperature at the corresponding pressure by 0.4℃±0.1℃, and the output value of TIC1563 is used as the compensation amount of FSP1563, and the compensation range does not exceed 8% of the rated value of FSP1563.

[0028] As a preferred method, the method further includes the following steps:

[0029] The initial setting value FSP1657 of the dirty liquid nitrogen flow is calculated based on 0.287 times the total air flow FSP1294: FSP1657=FSP1294×0.287, and the FSP1657 is cascade compensated by the detection value of the dirty nitrogen oxygen content analyzer AI1682, specifically:

[0030] The deviation between the set value and the actual value of AI1682 is input into the AIC1682 PID control module, and the output compensation amount is added to the FSP1657. The compensation range is limited to ±5000 Nm³ / h to keep the reflux ratio between the high-pressure tower and the low-pressure tower at the predetermined value.

[0031] As a preference, the method further includes the following steps:

[0032] The raw fraction flow rate FI1716 extracted from the low-pressure tower of the main distillation tower is detected by DCS. Based on the total air flow FSP1294, the raw fraction flow rate set value FSP1716 of the argon distillation tower is calculated: FSP1716=FSP1294×0.2, and the crude argon condenser heat load evaporation control valve FV1712 is adjusted through the FIC1716 PID control loop of DCS.

[0033] Preferably, all flow setting values ​​output by the APC system are set with dynamic upper and lower limits, and are locked to the limit when exceeding the limit; and the APC system is linked with the DCS interlock signal. When the air separation unit triggers the shutdown interlock, the APC automatically switches to manual mode and freezes the output, wherein:

[0034] The flow setting value includes:

[0035] The set value of oxygen 1 product flow is 0.38MPa;

[0036] The set value of oxygen 2 product flow is 0.6MPa;

[0037] The set value of oxygen 3 product flow rate is 1.3MPa;

[0038] The set value of the pressure nitrogen flow rate is 1.1 MPa.

[0039] The present invention has at least the following beneficial effects:

[0040] 1. The DCS system monitors oxygen demand during the smelting process in real time, combined with the dynamic calculation capabilities of the APC system, to achieve fully automatic linkage control of the air separation unit load and the smelting process. This eliminates the need for manual target setting or operational intervention, significantly reducing labor costs and eliminating human error.

[0041] 2. Based on material composition balance and thermodynamic equilibrium, the APC system dynamically adjusts the parameters of each process unit of the air separation unit through feedforward control, including the feed air flow rate and the distillation tower reflux ratio. At the same time, it ensures the stability of the unit under variable load conditions and avoids system oscillations caused by hysteresis in traditional control.

[0042] 3. A cascade control loop is embedded in the DCS system to provide real-time compensation for flow rate detection errors and deviations in the distillation tower's gas-liquid equilibrium temperature. By correcting the total raw air flow, distillation tower temperature fluctuations are controlled within a reasonable range to ensure the quality stability of high-purity oxygen and nitrogen products while avoiding the risk of cascading downtime caused by a single sensor failure.

[0043] 4. The APC system is responsible for the dynamic solution of multi-variable coupling relationships, while the DCS system focuses on command execution and local closed-loop control, so as to facilitate expansion to the coordinated control of other industrial gases. Its compatibility is significantly better than that of traditional centralized control systems.

[0044] 5. Through direct feedback control of the external oxygen flow rate, the air separation unit's production capacity is matched to smelting needs in real time, reducing the oxygen venting rate. At the same time, the linkage control allows the air separation unit to operate within the optimal load rate range, greatly reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 A schematic diagram of the TIC1616 provided in the first embodiment of the present invention as the main process control loop of this cascade control;

[0047] Figure 2 A schematic diagram of the AIC1682 provided in the first embodiment of the present invention as the main process control loop of this cascade control;

[0048] Figure 3 This is a schematic diagram of the main heat exchanger materials provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0050] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0051] Example 1

[0052] This embodiment provides a load-following automatic tracking control method for an air separation unit in non-ferrous metal smelting. The method is implemented in real-time online linkage with the air separation unit based on the oxygen consumption load patterns and characteristics of the special production processes of non-ferrous metal smelting. By matching the oxygen load supplied by the process system of the air separation unit with the gas consumption load of the smelting process system, the DCS detects and collects the oxygen flow rate of the process output product of the air separation unit. Based on this flow rate, an automatic load change APC system calculation module for the air separation unit is introduced to automatically calculate the target flow rate setpoints of process control loops related to the air separation unit and product oxygen. Furthermore, automatic load control of each process unit and unit of the unit is achieved through their respective loops.

[0053] The method comprises the following steps: Figure 1 As shown:

[0054] S01. Use the DCS system to detect the flow rate data of oxygen products delivered from the air separation unit in real time. The flow rate data includes:

[0055] Oxygen 1 product flow rate obtained by FI1511 detection;

[0056] Oxygen 2 product flow rate obtained by FI1512 detection;

[0057] Oxygen 3 product flow rate obtained by FI1513 detection;

[0058] The pressure nitrogen flow rate obtained by FI1501 detection;

[0059] S02. Use FSP1294 as the set value of the main raw material air compressor load control loop FIC1294, and perform closed-loop regulation of the compressor through the DCS system;

[0060] S03, APC system calculates the total raw air flow target value FSP1294 based on the oxygen extraction rate formula: Oxygen extraction rate = , where the total raw air volume is obtained by back calculation by the APC system;

[0061] In summary, the DCS system monitors oxygen delivered from the air separation unit, including three oxygen product specifications: oxygen 1 (0.38 MPa), oxygen 2 (0.6 MPa), and oxygen 3 (1.3 MPa), as well as pressurized nitrogen (1.1 MPa). Oxygen 1 is the primary product and is detected by the oxygen 1 product delivery flowmeter FI1511, oxygen 2 product delivery flowmeter FI1512, and oxygen 3 product delivery flowmeter FI1513. The DCS filters the actual flow rate and sends it to the APC system. The APC system calculates the oxygen extraction rate based on a preset formula.

[0062] Oxygen extraction rate = ;

[0063] The total feed air flow is calculated by APC based on the oxygen production using the above relationship;

[0064] The total oxygen production measured online is FI1511 + FI1512 + FI15513. These three indicators are obtained through DCS monitoring and then sent to the APC. Oxygen purity is also measured by the DCS and sent to the APC for calculation. The total air flow is calculated using the oxygen production data according to the above relationship. The total air volume calculated by the APC, FSP1294, is sent to the DCS and serves as the setpoint for the PID control loop corresponding to FIC1294, which automatically controls the load of the raw material main air compressor.

[0065] After calculation, the total processing air flow is given the control target value FSP1294. This target value is used as the automatic control load set value for the main raw material air compressor. The APC system transmits FSP1294 to the DCS, which is used as the set value for the DCS's automatic load control loop for the unit. This achieves automatic control of the air compressor load after changes in the product structure and smelting system match, thereby achieving energy conservation and efficiency improvement. In order to effectively overcome the impact of flow detection and control lag, the DCS internally designs a core key process control variable main control loop to achieve cascade automatic compensation correction for FSP1294. However, this cascade automatic compensation correction serves only as a precise control loop, not the main control loop. The main control loop is the FSP1294 obtained by the APC system through the oxygen extraction rate calculation formula. Based on this data transmitted to the DCS, it is corrected within a certain range to serve as the automatic control of the air compressor load. The core process control indicator of the DCS internal design, the cascade correction main loop, is the sensitivity temperature of the gas-liquid equilibrium in the distillation process of the reaction distillation tower. This point is the key core process control indicator calculated based on process simulation theory, and is the core process control indicator of the entire air separation unit. No matter how the products and unit load of the air separation unit change, the reflux ratio of each section of the main distillation tower should remain unchanged, so as to ultimately achieve the designed distillation gas-liquid equilibrium temperature and achieve stable control of the core distillation unit. The core process control variable controlled by this cascade process loop is the sensitivity temperature of the upper tower of the distillation tower, which is set to -188°C. It reflects the reflux ratio of the packing section in the sensitive area of ​​the distillation tower, and also indirectly reflects the controlled product purity indicator.

[0066] S04. Arrange TI1616 detection based on the gas-liquid equilibrium temperature point in the sensitive area of ​​the distillation tower, and dynamically compensate and correct FSP1294 through the TIC1616-PID control loop to stabilize TI1616 within the range of -188℃±0.5℃:

[0067] Specific, combined Figure 2 As shown, specifically:

[0068] TIC1616: DCS internal PID function control block;

[0069] FIC1294: DCS internal PID function control block;

[0070] ADD: DCS internal adder block;

[0071] SPcrt: The corresponding distillation column sensitivity control temperature given by the DCS operator;

[0072] TIC1616: OUT is the PID block output terminal: the DCS internal PID block output range is limited to + / -6000nm3 / h to ensure a certain range of compensation;

[0073] FSP1294 is an external given variable calculated within the APC based on oxygen production, and is relayed from the APC system to the DCS system;

[0074] TI1616: Core process control indicators of the main distillation tower of the air separation unit, distillation tower distillation gas-liquid equilibrium sensitivity temperature;

[0075] (TI1616+273.15) is converted into thermodynamic temperature and amplified before the data is sent to the TIC1616 control block to improve detection accuracy. The normal control range of TI1616 is between -186.5 and -188.5℃. DCS retains two decimal places of accuracy. The optimal temperature value of this sensitive point is -188℃.

[0076] TIC1616 is the main process control loop of this cascade control and also the core key process control variable main control loop. It is a PID control loop. Through this main process control loop, FSP1294 is compensated and used as the given value of the unit load PID control of FIC1294.

[0077] Furthermore, the above-mentioned dynamic compensation correction step includes: converting the TI1616 detection value into thermodynamic temperature and amplifying it by 1000 times, and then inputting it into the TIC1616-PID control module, whose output is limited to ±6000 Nm³ / h;

[0078] The FSP1294 is then corrected in real time through the adder module, and the correction range does not exceed ±5% of the initial value of the FSP1294;

[0079] In order to improve the DCS control accuracy, TSP1563 and TI1563 are both multiplied by the amplification factor 1000 and used as the PID control loop data of TIC1563.

[0080] The corresponding PID output of TIC1563 is used as compensation for FSP1563 within a certain range (8% of the rated value of FI1563).

[0081] The core process unit of the air separation process, the medium-pressure tower K01, undergoes initial distillation of air, forming product-pressure nitrogen at the top. The oxygen-rich liquid air at the bottom of the tower enters the low-pressure tower K02 for further distillation. When the load of the air separation unit changes, the PID control of the liquid level at the bottom of the K01 tower automatically transports the oxygen-rich liquid air to K02. The dirty liquid nitrogen extracted from the middle of K01 is sent to the low-pressure tower as the distillation reflux liquid of the low-pressure tower.

[0082] For the distillation system of the core process unit of the air separation unit, ensuring the relative stability of the reflux ratio of each packing section of the distillation tower during changes in the unit's load is a critical factor. To achieve this goal, in order to maintain the stability of the reflux ratio data of each packing section of the distillation tower during changes in the unit's load, it is necessary to change the feed flow rate of each distillation tower section to match the corresponding process air volume. The flow rate FSP1657 of the dirty liquid nitrogen extracted from the medium-pressure tower K01 to the low-pressure tower K02 is linearly proportional to the total process air volume of the air separation unit. Based on the total air flow data and this given proportionality coefficient, the APC calculates the dirty liquid nitrogen flow rate FSP1657. The APC transmits the FSP1657 data to the DCS, and controls the process loop FIC1657 within the DCS. In order to compensate for the error caused by flow detection, a cascade control main process loop is set up inside the DCS, that is, the oxygen content AI1682 in the contaminated nitrogen gas at the top of the upper tower is used as the main process control variable. The PID control output of the cascade control main process loop inside the DCS is used as the cascade correction of the given value FSP1657 of the PID control loop FIC1657. This cascade correction only makes certain compensation within the specified process range to overcome the FSP1657 calculation deviation caused by instrument flow detection errors and other minor process disturbance factors.

[0083] S05. Calculate the boost air flow rate FSP1563 based on 1.25 times FI1511, and calculate the high-pressure air flow rate FSP1536 based on 1.3 times the sum of FI1512, FI1513, and FI1501. Then, control the heat source flows of the liquid oxygen evaporator heat exchanger and the main heat exchanger separately through the DCS system.

[0084] The calculation formula for the charge air flow FSP1563 is as follows:

[0085] Oxygen 1 supporting boost air flow setting value: FSP1563=FI1511×1.25;

[0086] The setting value of the high-pressure air flow rate for oxygen 2 product flow, oxygen 3 product flow and pressurized nitrogen flow is: FSP1536=(FI1512+FI1513+FI1501)×1.3;

[0087] Among them, FI1501 is the pressure nitrogen flow rate, the flow ratio of booster air to liquid oxygen evaporator heat exchanger is 1.25:1, and the flow ratio of high-pressure air to oxygen 2 product flow rate, oxygen 3 product flow rate and pressure nitrogen flow rate is 1.3:1.

[0088] Specifically, the liquid oxygen evaporation heat exchanger and liquid-to-air subcooler involved in the oxygen 1 product flow rate are both aluminum plate-fin heat exchangers. Because the evaporation working pressure of oxygen 1 in the evaporator is relatively low (only 3.8 bar), for safety reasons, a liquid oxygen immersed plate-fin heat exchanger unit is used, which is a typical bath-type heat exchanger. The low-pressure liquid oxygen pressurized by the liquid oxygen pump is reheated through the liquid-to-air subcooler to form liquid oxygen close to saturation. The liquid-to-air subcooler is a non-bath-type heat exchanger. In order to avoid the dry evaporation safety risk caused by the generation of gas after the liquid oxygen is reheated in the liquid-to-air subcooler, the liquid oxygen enters the liquid oxygen after passing through the subcooler. The temperature before the evaporator is a key process control indicator related to process safety. In the technology of this application, a cascade control process loop is set up inside the DCS. The controlled liquid oxygen temperature is TI1563. This indicator needs to be 0.4°C lower than the saturation temperature at the corresponding oxygen evaporation pressure. As the TSP1563 target value, the PID process control loop TIC1563 set up inside the DCS is used to control the heat exchange heat source boost air flow rate. Among them, TSP1563 is automatically calculated within the DCS based on the oxygen evaporator working pressure PI1563. The given target value of TSP1563 is calculated.

[0089] S06. When the DCS system detects a failure in any of the flow meters FI1511, FI1512, and FI1513, the APC system stops outputting FSP1294 and triggers an alarm, while keeping FIC1294 at the pre-fault setting until the failure is resolved.

[0090] When the DCS detects a fault in the data sent to the APC, a similar situation occurs as follows:

[0091] If FI1511 / 1512 / 1513 fails, the APC will stop the FSP1294 calculation output, the DCS will prompt an alarm, the FSP1294 sent by the APC corresponding to the FIC1294 will be frozen, and the pre-failure data will be retained. The DCS operator will receive an alarm message. The instrumentation specialist will then need to handle the instrument failure.

[0092] In addition, in order to avoid overshoot in APC system calculation and DCS system control, upper and lower limits are set for the output FSP of each AP system C calculation loop. When the upper and lower limits are exceeded, the corresponding output limit will be maintained to avoid overshoot.

[0093] The APC system serves solely as a load-following control system during normal operation of the air separation unit. It ensures process integration with the subsequent nonferrous metal smelting system during normal production, enabling unmanned operation during normal operation. The main process control system for the air separation unit remains the DCS, and the APC system merely calculates process-related flow path variables and processes the output of these calculation results. The air separation unit's process safety interlocks, rotating equipment and other process controls for related process subsystems, and logic for determining equipment start and stop conditions are all implemented within the DCS. When an interlock function is triggered, the APC system receives a shutdown signal from the DCS, disabling all corresponding calculation functions and operating modes. Operators can also analyze and assess specific situations during unit operation based on data from equipment, instrumentation, and analyzers. If a data failure is detected, the corresponding APC control loop can be disabled, or even completely disabling APC, ensuring basic DCS process control and ensuring plant operation.

[0094] As an embodiment further provided by the present invention, the step of controlling the safe temperature of the liquid oxygen evaporator is further included:

[0095] The liquid oxygen temperature TI1563 is detected by the DCS system, and the target temperature TSP1563 is dynamically calculated based on the evaporator pressure PI1563: , where P0 is the atmospheric pressure at the location of the air separation unit;

[0096] The boost air flow FSP1563 is adjusted through the TIC1563 PID control loop to make TI1563 lower than the saturation temperature at the corresponding pressure by 0.4℃±0.1℃, and the output value of TIC1563 is used as the compensation amount of FSP1563, and the compensation range does not exceed 8% of the rated value of FSP1563.

[0097] In the above, a cascade control process loop is set up inside the DCS. The controlled liquid oxygen temperature is TI1563. This indicator needs to be 0.4°C lower than the saturation temperature at the corresponding oxygen evaporation pressure. It is used as the TSP1563 target value. The PID process control loop TIC1563 set up inside the DCS is used to control the boost air flow rate of the heat exchange heat source. Among them, TSP1563 is automatically calculated in the DCS based on the oxygen evaporator working pressure PI1563.

[0098] As another embodiment further provided by the present invention, Figure 3 It also includes the dirty liquid nitrogen flow follow-up control steps:

[0099] The initial setting value FSP1657 of the dirty liquid nitrogen flow is calculated based on 0.287 times the total air flow FSP1294: FSP1657=FSP1294×0.287, and the FSP1657 is cascade compensated by the detection value of the dirty nitrogen oxygen content analyzer AI1682, specifically:

[0100] The deviation between the set value and the actual value of AI1682 is input into the AIC1682 PID control module, and the output compensation amount is added to the FSP1657. The compensation range is limited to ±5000 Nm³ / h to keep the reflux ratio between the high-pressure tower and the low-pressure tower at the predetermined value.

[0101] As mentioned above, for the distillation system of the core process unit of the air separation unit, ensuring the reflux ratio of each packing section of the distillation tower is relatively stable during the load changes of the air separation unit is an extremely critical factor. To achieve this goal, in order to maintain the reflux ratio data of each packing section of the distillation tower during the load changes of the unit, it is necessary to change the feed flow rate of each section of the distillation tower to match the corresponding process air volume. The flow rate FSP1657 of the dirty liquid nitrogen extracted from the medium-pressure tower K01 to the low-pressure tower K02 is linearly proportional to the total process air volume of the air separation unit. Based on the total air flow data and this given proportional coefficient, the APC calculates the dirty liquid nitrogen flow rate FSP1657. The APC transmits the FSP1657 data to the DCS, and controls the process loop FIC1657 within the DCS. In order to compensate for the error caused by flow detection, a cascade control main process loop is set up inside the DCS, that is, the oxygen content AI1682 in the contaminated nitrogen gas at the top of the upper tower is used as the main process control variable. The PID control output of the cascade control main process loop inside the DCS is used as the cascade correction of the given value FSP1657 of the PID control loop FIC1657. This cascade correction only makes certain compensation within the specified process range to overcome the FSP1657 calculation deviation caused by instrument flow detection errors and other minor process disturbance factors.

[0102] AIC1682 is the main process control loop of this cascade control and is a PID control loop. Through this main process control loop, FSP1657 is compensated and used as the given value of the PID control of FIC1657.

[0103] As another embodiment further provided by the present invention, the present invention further includes the following steps of load following control of the argon distillation system:

[0104] The raw fraction flow rate FI1716 extracted from the low-pressure tower of the main distillation tower is detected by DCS. Based on the total air flow FSP1294, the raw fraction flow rate set value FSP1716 of the argon distillation tower is calculated: FSP1716=FSP1294×0.2, and the crude argon condenser heat load evaporation control valve FV1712 is adjusted through the FIC1716 PID control loop of DCS.

[0105] As mentioned above, in addition to the main distillation tower to achieve the separation of the main products oxygen and nitrogen, the air separation unit also needs to extract argon through the argon distillation system. The load of the argon distillation system also changes with the change of the total raw material air flow. The raw material fraction flow FI1716 extracted from the low-pressure tower K02 of the main distillation tower is detected by the DCS system. Based on the total air flow FSP1294 of the APC system, the raw material fraction flow that can be extracted under the corresponding FSP1294 load conditions is calculated to maintain the normal distillation conditions of the argon distillation tower and the main distillation tower. , APC transmits FSP1701 to the DCS system, and the DCS system controls the corresponding crude argon condenser heat load evaporation regulating valve FV1712 through the FIC1716 process control PID loop.

[0106] In summary, this first embodiment utilizes a DCS system to monitor oxygen demand during the smelting process in real time, combined with the dynamic computing capabilities of the APC system, to achieve fully automated, coordinated control of the air separation unit load and the smelting process. This eliminates the need for manual target setting or operational intervention, significantly reducing labor costs and eliminating human error. Furthermore, based on material composition and thermodynamic equilibrium, the APC system dynamically adjusts parameters of each process unit in the air separation unit, including the feed air flow rate and the distillation column reflux ratio, through feedforward control. This ensures the stability of the unit under variable load conditions and avoids system oscillations caused by hysteresis in traditional control. Furthermore, a cascade control loop is embedded in the DCS system to provide real-time compensation for flow rate detection errors and deviations from the distillation column gas-liquid equilibrium temperature. By correcting the total feed air flow rate, distillation column temperature fluctuations are controlled within a reasonable range, ensuring the quality stability of high-purity oxygen and nitrogen products while avoiding the risk of cascading downtime caused by a single sensor failure. Furthermore, the APC system dynamically resolves multivariable coupling relationships, while the DCS system focuses on command execution and local closed-loop control, facilitating expansion to the coordinated control of other industrial gases. Its compatibility is significantly superior to traditional centralized control systems. Furthermore, through direct feedback control of the external oxygen flow rate, the ASU's production capacity is matched to smelting demand in real time, reducing the oxygen venting rate. Simultaneously, linked control allows the ASU to operate within the optimal load range, significantly reducing energy consumption.

[0107] Example 2

[0108] An embodiment of the present invention provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores at least one instruction or at least one program, and the at least one instruction or at least one program is loaded and executed by a processor to implement the steps:

[0109] The DCS system is used to monitor the flow rate of oxygen products delivered from the air separation unit in real time. The flow rate data includes:

[0110] Oxygen 1 product flow rate obtained by FI1511 detection;

[0111] Oxygen 2 product flow rate obtained by FI1512 detection;

[0112] Oxygen 3 product flow rate obtained by FI1513 detection;

[0113] The pressure nitrogen flow rate obtained by FI1501 detection;

[0114] Use FSP1294 as the set value of the main raw material air compressor load control loop FIC1294, and perform closed-loop regulation of the compressor through the DCS system;

[0115] The APC system calculates the total raw air flow target value based on the oxygen extraction rate formula FSP1294: Oxygen extraction rate = , where the total raw air volume is obtained by back calculation by the APC system;

[0116] TI1616 detection is arranged based on the gas-liquid equilibrium temperature point in the sensitive area of ​​the distillation tower, and dynamic compensation correction is performed on FSP1294 through the TIC1616-PID control loop to stabilize TI1616 within the range of -188℃±0.5℃;

[0117] The boost air flow FSP1563 is calculated based on 1.25 times of FI1511, and the high-pressure air flow FSP1536 is calculated based on 1.3 times the sum of FI1512, FI1513 and FI1501. The heat source flows of the liquid oxygen evaporator heat exchanger and the main heat exchanger are controlled separately through the DCS system;

[0118] When the DCS system detects a failure in any of the flow meters FI1511, FI1512, and FI1513, the APC system stops outputting FSP1294 and triggers an alarm, while keeping FIC1294 at the pre-fault setting until the fault is resolved.

[0119] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing the relevant hardware using a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the above-described method embodiments. Any reference to memory, storage, database, or other media used in the various embodiments provided herein may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct RAMbus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM).

[0120] Those skilled in the art will clearly understand that for the sake of convenience and brevity in description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0121] Example 3

[0122] An embodiment of the present invention provides an electronic device, including a processor and a memory, wherein the memory stores at least one instruction or at least one program, and the at least one instruction or at least one program is loaded and executed by the processor to implement the following steps:

[0123] The DCS system is used to monitor the flow rate of oxygen products delivered from the air separation unit in real time. The flow rate data includes:

[0124] Oxygen 1 product flow rate obtained by FI1511 detection;

[0125] Oxygen 2 product flow rate obtained by FI1512 detection;

[0126] Oxygen 3 product flow rate obtained by FI1513 detection;

[0127] The pressure nitrogen flow rate obtained by FI1501 detection;

[0128] Use FSP1294 as the set value of the main raw material air compressor load control loop FIC1294, and perform closed-loop regulation of the compressor through the DCS system;

[0129] The APC system calculates the total raw air flow target value based on the oxygen extraction rate formula FSP1294: Oxygen extraction rate = , where the total raw air volume is obtained by back calculation by the APC system;

[0130] TI1616 detection is arranged based on the gas-liquid equilibrium temperature point in the sensitive area of ​​the distillation tower, and dynamic compensation correction is performed on FSP1294 through the TIC1616-PID control loop to stabilize TI1616 within the range of -188℃±0.5℃;

[0131] The boost air flow FSP1563 is calculated based on 1.25 times of FI1511, and the high-pressure air flow FSP1536 is calculated based on 1.3 times the sum of FI1512, FI1513 and FI1501. The heat source flows of the liquid oxygen evaporator heat exchanger and the main heat exchanger are controlled separately through the DCS system;

[0132] When the DCS system detects a failure in any of the flow meters FI1511, FI1512, and FI1513, the APC system stops outputting FSP1294 and triggers an alarm, while keeping FIC1294 at the pre-fault setting until the fault is resolved.

[0133] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A load following automatic tracking control method for an air separation unit for non-ferrous metal smelting, characterized in that: The method comprises the following steps: S01. Detect the flow rate data of oxygen products delivered by the air separation unit in real time through the DCS system. The flow rate data includes: Oxygen 1 product flow rate obtained by FI1511 detection; Oxygen 2 product flow rate obtained by FI1512 detection; Oxygen 3 product flow rate obtained by FI1513 detection; The pressure nitrogen flow rate obtained by FI1501 detection; S02, using FSP1294 as the set value of the main raw material air compressor load control loop FIC1294, and performing closed-loop regulation of the compressor through the DCS system; S03. The APC system calculates a total raw air flow target value FSP1294 based on the oxygen extraction rate formula: oxygen extraction rate = ((FI1511 + FI1512 + FI1513) * oxygen purity) / (total raw air volume * 0.2095), where the total raw air volume is obtained by reverse calculation by the APC system; S04. Arrange TI1616 detection based on the gas-liquid equilibrium temperature point in the sensitive area of ​​the distillation tower, and dynamically compensate and correct FSP1294 through the TIC1616-PID control loop to stabilize TI1616 within the range of -188℃±0.5℃; S05. Calculate the boost air flow rate FSP1563 based on 1.25 times the FI1511, calculate the high-pressure air flow rate FSP1536 based on 1.3 times the sum of FI1512, FI1513, and FI1501, and control the heat source flows of the liquid oxygen evaporator heat exchanger and the main heat exchanger respectively through the DCS system; S06. When the DCS system detects that any flow meter among FI1511, FI1512, and FI1513 fails, the APC system stops outputting FSP1294 and triggers an alarm, while keeping the FIC1294 at the pre-fault setting value until the failure is resolved; The dynamic compensation correction step in step S04 includes: converting the TI1616 detection value into thermodynamic temperature and amplifying it by 1000 times, and then inputting it into the TIC1616-PID control module, whose output is limited to ±6000 Nm³ / h; The FSP1294 is then corrected in real time through the adder module, and the correction range does not exceed ±5% of the initial value of the FSP1294; The normal control range of the TI1616 is -186.5°C to -188.5°C, and the DCS system retains two decimal places of accuracy; The calculation formula of the boost air flow FSP1563 in step S05 is: Oxygen 1 supporting boost air flow setting value: FSP1563=FI1511×1.25; The setting value of the high-pressure air flow rate for oxygen 2 product flow, oxygen 3 product flow and pressurized nitrogen flow is: FSP1536=(FI1512+FI1513+FI1501)×1.3; Among them, FI1501 is the pressure nitrogen flow rate, the flow ratio of the boosted air to the liquid oxygen evaporator heat exchanger is 1.25:1, and the flow ratio of the high-pressure air to the oxygen 2 product flow rate, the oxygen 3 product flow rate and the pressure nitrogen flow rate is 1.3:1; Also included are the steps for safe temperature control of liquid oxygen vaporizers: The liquid oxygen temperature TI1563 is detected by the DCS system, and the target temperature TSP1563 is dynamically calculated based on the evaporator pressure PI1563: TSP1563=(374.5 / (6.129−lg(PI1563+P0))−273.6, where P0 is the atmospheric pressure at the location of the air separation unit; The pressurized air flow FSP1563 is regulated through the TIC1563 PID control loop to make TI1563 0.4℃±0.1℃ lower than the saturation temperature at the corresponding pressure. The output value of TIC1563 is used as the compensation amount of FSP1563, and the compensation range does not exceed 8% of the rated value of FSP1563. It also includes the dirty liquid nitrogen flow follow-up control steps: The initial setting value FSP1657 of the dirty liquid nitrogen flow is calculated based on 0.287 times the total air flow FSP1294: FSP1657=FSP1294×0.287, and the FSP1657 is cascade compensated by the detection value of the dirty nitrogen oxygen content analyzer AI1682, specifically: The deviation between the set value and the actual value of AI1682 is input into the AIC1682 PID control module, and the output compensation amount is added to the FSP1657. The compensation range is limited to ±5000 Nm³ / h to keep the reflux ratio between the high-pressure tower and the low-pressure tower at the predetermined value.

2. The method for automatically tracking and controlling load of an air separation unit for non-ferrous metal smelting according to claim 1, characterized in that: It also includes the following steps for load following control of the argon distillation system: The raw fraction flow rate FI1716 extracted from the low-pressure tower of the main distillation tower is detected by DCS. Based on the total air flow FSP1294, the raw fraction flow rate set value FSP1716 of the argon distillation tower is calculated: FSP1716=FSP1294×0.2, and the crude argon condenser heat load evaporation regulating valve FV1712 is adjusted through the FIC1716 PID control loop of DCS.

3. The load following automatic tracking control method for an air separation unit for non-ferrous metal smelting according to claim 1 is characterized in that: All flow setting values ​​output by the APC system are set with dynamic upper and lower limits, and are locked to the limit when exceeding the limit; and the APC system is linked with the DCS interlock signal. When the air separation unit triggers the shutdown interlock, the APC automatically switches to manual mode and freezes the output, where: The flow setting value includes: The set value of oxygen 1 product flow is 0.38MPa; The set value of oxygen 2 product flow is 0.6MPa; The set value of oxygen 3 product flow rate is 1.3MPa; The set value of the pressure nitrogen flow rate is 1.1 MPa.

4. A non-transitory computer-readable storage medium, wherein at least one instruction or at least one program is stored in the non-transitory computer-readable storage medium, characterized in that: The at least one instruction or the at least one program segment is loaded and executed by the processor to implement the load following automatic tracking control method for an air separation unit for non-ferrous metal smelting as described in any one of claims 1-3.

5. An electronic device, characterized in that: It includes a processor and a memory, wherein the memory stores at least one instruction or at least one program, and the at least one instruction or the at least one program is loaded and executed by the processor to implement the load following automatic tracking control method of the air separation unit for non-ferrous metal smelting as described in any one of claims 1 to 3.

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