Low temperature rectification optimization control strategy for air separation distillation column based on sensitivity analysis

Abstract

The application is a low-temperature rectification optimization control strategy of an air separation rectification tower based on sensitivity analysis, and relates to the technical field of computer processing, which comprises the following steps: S01, detecting the temperature and tower pressure data of a sensitive area of a rectification tower in an air separation device in real time through a DCS system, wherein the sensitive area is a packing section with the largest concentration gradient change in the rectification tower; S02, obtaining the temperature and tower pressure data of the sensitive area of the rectification tower in real time, combining a preset gas-liquid equilibrium function relationship, and dynamically calculating the gas phase and liquid phase component concentrations of the sensitive area of the rectification tower; and S03, comparing the calculated gas phase and liquid phase component concentrations with design values. The application establishes a function model between the gas-liquid equilibrium parameters of the sensitive temperature interval and the component of the argon raw material suction port, combines the temperature-concentration curve of the process simulation software and the sensitivity analysis data, and calculates the nitrogen and oxygen impurity concentrations in the argon raw material in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of computer processing, in particular to a low-temperature rectification optimization control strategy for air separation rectification column based on sensitivity analysis. BACKGROUND

[0002] In the air separation device, the main rectification column is the core equipment for separating oxygen, nitrogen, argon and other gas components, and its stable operation directly determines the product purity and yield. The reflux ratio (i.e. the flow ratio of the downflowing liquid to the rising vapor) of each packing section of the rectification column is a key parameter for maintaining gas-liquid balance and separation efficiency. If the reflux ratio fluctuates, it will cause the temperature distribution in the column to change, breaking the gas-liquid balance state, and then affecting the component concentration distribution, ultimately reducing the product purity. However, the traditional control method relies on the purity analysis data (such as oxygen and nitrogen purity) of the end product to adjust the process parameters, which has significant technical defects:

[0003] 1. Detection transmission lag: the product purity needs to be detected by a cold box external analyzer, and there is a time delay in the process of transmitting the sample from the process pipeline to the analyzer;

[0004] 2. Process purity lag: the product sampling point is located in the concentration section of the rectification column, and the state adjustment needs to go through the multi-stage rectification process in the column, resulting in a control response lag.

[0005] 3. The superimposed effect of detection transmission lag and process purity lag makes it difficult for traditional control to respond to changes in working conditions in a timely manner, especially when the load fluctuates or external disturbances occur, which can easily cause unstable product quality.

[0006] 3. The argon raw material is sampled from the stripping section of the low-pressure rectification column, which has a small concentration gradient, and the functional relationship between the gas-liquid balance temperature and the component concentration cannot accurately reflect the changes in the nitrogen and oxygen impurity content in the argon raw material. The traditional method relies on a physical analyzer to monitor the argon raw material components, but due to the characteristics of the stripping section, it is difficult to achieve real-time monitoring through temperature-concentration soft measurement technology.

[0007] To solve the above problems, the existing technology attempts to indirectly control through the correlation between the temperature sensitive point in the rectification column and the component concentration. For example, in the packing section with a large concentration gradient (such as the lower packing section corresponding to the liquid air vapor from the crude argon condenser evaporation entering the upper column), the oxygen and nitrogen component concentrations are calculated by the gas-liquid balance temperature and pressure data, so as to build a soft measurement model and shorten the control response time. However, this method cannot be directly applied to the monitoring of the argon raw material stripping section, as the temperature-concentration relationship is not sensitive, resulting in the quality control of the argon rectification raw material still relying on offline analysis, which is inefficient. SUMMARY

[0008] To solve the above technical problems, the technical solution adopted by the present application is a low-temperature rectification optimization control strategy for air separation rectification column based on sensitivity analysis, which comprises the following steps:

[0009] S01, detecting the temperature and column pressure data of the sensitive region of the rectifying column in the air separation device in real time through the DCS system, the sensitive region being the packing section with the largest concentration gradient change in the rectifying column;

[0010] S02, dynamically calculating the gas phase and liquid phase component concentrations of the sensitive region of the rectifying column by combining the preset gas-liquid equilibrium function relationship with the obtained real-time temperature and column pressure data of the sensitive region of the rectifying column;

[0011] S03, comparing the calculated gas phase and liquid phase component concentrations with design values, and controlling the gas phase and liquid phase component concentrations within a set threshold range by adjusting the reflux ratio or feed quantity of the rectifying column;

[0012] S04, monitoring the oxygen content in the crude argon product at the top of the crude argon column in real time, and maximizing the crude argon production when the oxygen content is ≤1 ppm to prevent the argon component from flowing back to the stripping section of the low-pressure column;

[0013] S05, dynamically adjusting the temperature set value of the sensitive region of the medium-pressure column, the low-pressure column and the crude argon column according to the load change, so that the working condition of the rectifying column automatically tracks the load change to maintain the optimal state at all times.

[0014] As preferred, the method for dividing the sensitive region of the rectifying column in step S03 comprises:

[0015] The sensitive region of the low-pressure column is located above the gas-liquid distributor interval of the packing section corresponding to the oxygen-rich air feed port evaporated from the crude argon condenser, the temperature gradient change rate of the corresponding packing section is ≥5 ℃ / m, and the temperature set value is -188 ℃±0.3 ℃;

[0016] The sensitive region of the medium-pressure column is located at the bottom of the oxygen-rich liquid air pipeline, and the detection temperature is -176 ℃±1 ℃;

[0017] The sensitive region of the crude argon column is located in the middle packing section, and the temperature set value is -183.6 ℃±0.5 ℃.

[0018] As preferred, when the gas phase argon component concentration is ≤2% in the sensitive region of the rectifying section of the low-pressure column, a binary rectification model of oxygen and nitrogen is simplified, and the argon component is ignored, at this time, xar=0, yar=0, xo2+xn2=1, yo2+yn2=1.

[0019] As preferred, the oxygen concentration design threshold in step S03 is:

[0020] The design value of the oxygen concentration in the gas phase in the sensitive region of the low-pressure column is 30%±1%;

[0021] The design value of the oxygen concentration in the liquid phase at the bottom of the medium-pressure column is 41%±2%.

[0022] Preferably, the gas-liquid equilibrium function relationship in step S02 comprises the following formula:

[0023] Oxygen component equilibrium formula:

[0024]

[0025] Nitrogen component equilibrium formula:

[0026]

[0027] Argon component equilibrium formula:

[0028]

[0029] wherein T is the thermodynamic temperature, t is the detection temperature, P is the distillation column pressure, and the liquid phase and gas phase concentrations satisfy:

[0030] .

[0031] Preferably, the dynamic adjustment in step S05 specifically comprises:

[0032] When the air separation device load increases, the temperature set value of the low-pressure column sensitive region is reduced by 0.1-0.5°C from the design value of -188°C, and the column pressure is set to 1.13 atm±0.02 atm;

[0033] When the air separation device load decreases, the temperature set value of the low-pressure column sensitive region is increased by 0.1-0.5°C from the design value of -188°C, and the column pressure is simultaneously adjusted to 1.13 atm±0.02 atm.

[0034] Preferably, the calculation method of the column pressure data in step S01 comprises:

[0035] S11, the overhead pressure P 顶 and the bottom pressure P 底 of the distillation column are collected in real time through the DCS system, and the arithmetic average of the two is calculated as the distillation column pressure P, and the formula is as follows: P=(P 顶 +P 底 ) / 2;

[0036] S12, the pressure difference between the overhead and the bottom needs to satisfy: If the pressure difference is out of limit, the DCS system triggers an alarm and automatically adjusts the operation parameters of the distillation column to restore the pressure difference to the allowable range.

[0037] Preferably, the control of the oxygen content in the crude argon product at the top of the crude argon column in step S04 is realized by a PID algorithm, and the linear relationship between the set value and the air separation device load is: Q 采出=k·L+b, wherein Q 采出 is the crude argon production flow, L is the percentage of the load of the air separation unit, k is the load-flow ratio coefficient, and b is the basic flow constant.

[0038] The present application has at least the following beneficial effects:

[0039] 1. By replacing the traditional analyzer with soft-sensing technology, the temperature and pressure parameters of the sensitive area of the rectification tower are detected in real time based on DCS, the component concentration is dynamically calculated based on the gas-liquid equilibrium function, and the sampling lag is eliminated, so as to realize instant feedback and closed-loop control of the rectification condition. In the sensitive area (such as the rectification section of the low-pressure tower) where the concentration gradient changes greatly, the strong correlation between the temperature and the component concentration ensures the control accuracy, and the oxygen, nitrogen and argon components are effectively maintained within the design threshold.

[0040] 2. By dynamically adjusting the parameters such as reflux ratio and feed amount through the internal cascade control loop of DCS, the concentration gradient of the rectification tower is ensured to be highly consistent with the design range, the extraction rate of oxygen and nitrogen products is improved by 5%-10%, and the unit energy consumption is reduced. In the load fluctuation scenario (such as non-ferrous metal smelting), the temperature set value of the sensitive area is automatically tracked and adjusted to maintain the gas-liquid equilibrium state, and the efficiency loss caused by the change of working condition is avoided.

[0041] 3. In the sensitive area of the low-pressure tower, the medium-pressure tower and the crude argon tower, the soft-sensing technology is used to replace the liquid air analyzer, the fraction analyzer and other devices, so as to simplify the system architecture and greatly reduce the construction cost and maintenance cost. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0043] Figure 1 A flow chart of the low-temperature rectification optimization control strategy of the air separation rectification tower based on sensitivity analysis provided by the first embodiment of the present application. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0045] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and in the above drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or server including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0046] Embodiment one

[0047] The present embodiment provides a low-temperature rectification optimization control strategy for a space division rectification tower based on sensitivity analysis, which comprises the following steps, as shown in Figure 1

[0048] S01, real-time detection of temperature and tower pressure data of the sensitive area of the rectification tower in the air separation device through the DCS system, the sensitive area being the packing section with the largest concentration gradient change in the rectification tower;

[0049] Specifically, the calculation method of the above tower pressure data comprises:

[0050] S11, real-time acquisition of the tower top pressure P 顶 and the tower bottom pressure P 底 of the rectification tower through the DCS system, and calculation of the arithmetic mean of the two as the tower pressure P of the rectification tower, and the formula is as follows: P= (P 顶 +P 底 ) / 2;

[0051] S12, the pressure difference between the tower top and the tower bottom needs to meet: If the pressure difference is out of limit, the DCS system triggers an alarm and automatically adjusts the operation parameters of the rectification tower to restore the pressure difference to the allowable range.

[0052] In actual application:

[0053] A pressure acquisition module is set in the DCS system to obtain the data of the tower top and tower bottom pressure sensors in real time;

[0054] The average value is automatically calculated and substituted into the gas-liquid equilibrium formula to calculate the component concentration;

[0055] When the pressure difference is out of limit, the local resistance is reduced by adjusting the gas-liquid flow or reflux ratio in the tower to restore the pressure difference.

[0056] ​For example, in a low-pressure tower, the measured top pressure is 1.12 atm, the bottom pressure is 1.14 atm, and the pressure differential is 0.02 atm (≤ 0.05 atm). The calculated tower pressure is: P = (1.12 + 1.14) / 2 = 1.13 atm. This value is then directly substituted into the gas-liquid equilibrium formula to calculate the oxygen, nitrogen, and argon concentrations, ensuring they are consistent with the design values ​​(e.g., gas-phase oxygen concentration of 30%). If the pressure differential exceeds the limit (e.g., 0.06 atm), the DCS will automatically adjust the feed valve opening or reflux ratio until the pressure differential returns to the allowable range.

[0057] In the above technology, through the calculation program set within the DCS and the distillation tower sensitivity analysis design points designed based on ASPEN software during the process design process, the temperature index required by the soft measurement technology is implemented in the area where the concentration gradient of the distillation tower is the largest (that is, the gradient of the distillation gas-liquid equilibrium operating temperature). Due to the use of structured packing technology, the resistance of the distillation tower is significantly lower than that of the traditional plate tower, and the difference between the top and bottom pressures of the distillation tower is negligible. Therefore, when the distillation tower pressure data is used for calculation, the arithmetic average of the top and bottom pressures of the distillation tower is selected as the tower pressure data, which is fully capable of meeting the control accuracy requirements.

[0058] S02. The obtained real-time temperature and tower pressure data of the sensitive area of ​​the distillation tower are combined with a preset gas-liquid equilibrium function relationship to dynamically calculate the gas phase and liquid phase component concentrations in the sensitive area of ​​the distillation tower.

[0059] The above gas-liquid equilibrium function relationship includes the following formula:

[0060] Oxygen component balance formula:

[0061]

[0062] Nitrogen component balance formula:

[0063]

[0064] Argon composition equilibrium formula:

[0065]

[0066] The concentrations of liquid and gas phases satisfy:

[0067] .

[0068] Among them, Psn: nitrogen component saturated vapor pressure presents a single-valued function relationship with distillation temperature, unit: atm;

[0069] Pso: The saturated vapor pressure of oxygen component presents a single-valued function relationship with the distillation temperature, unit: atm;

[0070] Par: The single-valued function relationship between the saturated vapor pressure of argon component and the rectification temperature, unit: atm;

[0071] 1 atm = 101.33 kPa T: The rectification gas-liquid equilibrium temperature unit: ℃;

[0072] P: The rectification column pressure, unit atm;

[0073] t: The working temperature of the rectification column during the rectification process ℃;

[0074] T: The thermodynamic temperature corresponding to t K;

[0075] Yo2: The oxygen content in the gas phase of the packing section corresponding to the rectification temperature of the rectification column;

[0076] Yn2: The nitrogen content in the gas phase of the packing section corresponding to the rectification temperature of the rectification column;

[0077] Yar: The argon content in the gas phase of the packing section corresponding to the rectification temperature of the rectification column;

[0078] xo2: The oxygen content in the liquid phase of the packing section corresponding to the rectification temperature of the rectification column;

[0079] xn2: The nitrogen content in the liquid phase of the packing section corresponding to the rectification temperature of the rectification column;

[0080] xar: The argon content in the liquid phase of the packing section corresponding to the rectification temperature of the rectification column;

[0081] t: The actual detected sampling packing section temperature of the rectification column.

[0082] In the sensitive packing section of the low-pressure column rectification section, since the argon component in the gas phase is about 2%, and in the actual operation process of the air separation device, as long as the oxygen component concentration in the sensitive packing section of the low-pressure column rectification section is effectively controlled, the argon component and nitrogen component equilibrium composition in the rectification section can be effectively controlled, thereby ensuring that the nitrogen component in the raw material required for the argon system rectification process is controlled within the allowable value, so when controlling the rectification of the sensitive packing section of the low-pressure column rectification section, we use the binary rectification processing method for data processing, and only consider the oxygen and nitrogen component concentrations corresponding to the rectification column gas-liquid equilibrium temperature and gas-liquid equilibrium component, as long as the corresponding gas-liquid equilibrium temperature is controlled, the rectification working condition of each packing section of the low-pressure column can be effectively controlled in the optimal state.

[0083] Through the above functional correlation formulas, the distillation tower sensitive point temperature and distillation tower pressure detected by DCS, the concentration of the corresponding intermediate components in the distillation tower can be calculated through the above functional relationship, thereby avoiding the use of online analyzers to directly sample and analyze components. Since the distillation tower sensitivity temperature is the temperature detection set for the gas-liquid equilibrium distillation inside the distillation tower during process design, it can timely reflect the gas-liquid equilibrium composition under steady-state working conditions when the distillation tower is working, thereby effectively controlling the distillation conditions of the stripping section and the distillation section of the distillation tower, ensuring that the product quality is in a reliable state.

[0084] For the low-pressure tower, the area with the largest concentration difference based on gas-liquid equilibrium composition is around -188°C. The tower pressure of the distillation tower is generally in a relatively stable state. The working pressure of the low-pressure tower is around 1.13atm. Substituting the above two data into the above formula in turn, the design component concentration of the sensitive area with the largest concentration gradient of the low-pressure tower can be calculated: gas phase yo2=30%, liquid phase xo2=63%.

[0085] Since this area of ​​the low-pressure tower lies below the oxygen-rich liquid air feed section and above the argon feed outlet, the argon content is negligible during industrial process analysis and testing. Therefore, effectively controlling the oxygen concentration around this design point prevents the nitrogen content in the argon feed gas from exceeding the design value, thereby impacting the subsequent argon distillation tower operation. By effectively controlling the gas-liquid distillation equilibrium in the sensitive packing section of the low-pressure tower and maintaining a stable temperature of around -188°C, the corresponding oxygen composition can be effectively controlled. Since the distillation tower's sensitive temperature range is relatively small, even a 0.3°C fluctuation above the setpoint of -188°C will result in a change of at least 1% in oxygen concentration. Therefore, by using the internal relationship between distillation tower temperature and gas-liquid equilibrium composition within the DCS, the DCS detects the temperature at the sensitive point in the distillation tower packing section and then converts it into an oxygen concentration composition through calculation. This allows for faster reflection of changes in the tower's operating conditions, improving control accuracy and enabling timely and effective control.

[0086] S03. Compare the calculated gas phase and liquid phase component concentrations with the design values, and control the gas phase and liquid phase component concentrations within the set threshold range by adjusting the reflux ratio or feed rate of the distillation column;

[0087] Specifically, the method for dividing the sensitive areas of the above-mentioned middle distillation tower includes:

[0088] The sensitive area of ​​the low-pressure tower is located in the gas-liquid distributor area above the packing section corresponding to the oxygen-enriched air feed inlet from the crude argon condenser. The temperature gradient change rate of the corresponding packing section is ≥5℃ / m, and the temperature setting value is -188℃±0.3℃;

[0089] The sensitive area of the medium pressure column is located at the bottom of the oxygen-rich liquid air pipeline, and the detection temperature is -176℃±1℃;

[0090] The sensitive area of the crude argon column is located at the middle packing section, and the temperature set value is -183.6℃±0.5℃.

[0091] Further, in the sensitive area of the rectification section of the low pressure column, when the gas phase argon component concentration is ≤2%, a simplified oxygen-nitrogen binary rectification model is used, and the argon component is ignored, at this time, xar=0, yar=0, xo2+xn2=1, yo2+yn2=1.

[0092] Secondly, the above-mentioned medium oxygen concentration design threshold is:

[0093] The gas phase oxygen concentration design value of the sensitive area of the low pressure column is 30%±1%;

[0094] The liquid phase oxygen concentration design value of the bottom of the medium pressure column is 41%±2%.

[0095] In the above-mentioned technology, the medium pressure column is used to purify the raw material air after the preliminary rectification tower, and pure nitrogen gas is obtained at the top of the tower and oxygen-rich liquid air is obtained at the bottom of the tower. The oxygen-rich liquid air is then sent to the low pressure column for further rectification, and pure oxygen is formed at the bottom of the low pressure column, and normal pressure nitrogen gas is formed at the top of the low pressure column. The medium pressure column and the low pressure column each have a region with a large change in concentration gradient, and the region with the largest change in concentration gradient is also the region with the largest change in temperature gradient of the rectification tower, which is in a corresponding relationship. The low pressure column is a relatively complex device in the main rectification tower, and is divided into a rectification section (the region above the oxygen-rich liquid air feed port) and a stripping section (the region below the oxygen-rich liquid air feed port) according to the feed point from the medium pressure column to the low pressure column. The concentration gradient change in the stripping section of the low pressure column is small, and the working temperature change range of the rectification tower is not enough to reflect the significant change in concentration during the rectification process, but there is a region with a large change in concentration gradient in the rectification section of the low pressure column, that is, the concentration composition and temperature change rate of the rectification tower are larger with the unit change of the packing section height. This region is called the sensitive working area of the rectification tower, and by setting a temperature detection in the corresponding packing section of the rectification tower, the significant change in the rectification working condition can be obviously reflected through the small change in the temperature, that is, the region with a large change in concentration.

[0096] Through process flow ASPEN software analysis, it is known that for the low pressure column, there is a sensitive temperature distribution interval, and for the rectification section and the stripping section of the low pressure column, if the sensitive point temperature can be kept around the design value, the rectification working condition of the low pressure column will be in the optimal state, and the design value is between -187.5 and -188.5℃, and generally we take the set value as about -188℃. Based on the gas-liquid equilibrium principle, we can calculate the rectification working of the rectification tower according to the following relationship.

[0097] S04, monitoring the oxygen content in the crude argon product at the top of the crude argon column in real time, when the oxygen content is ≤1 ppm, maximizing the crude argon production to prevent the backflow of argon components to the low-pressure column stripping section;

[0098] Specifically, the control of the oxygen content in the crude argon product at the top of the crude argon column is realized by a PID algorithm, and through cascade control and external given calculation, the linear relationship between the set value and the load of the air separation device is: Q 采出 =k·L+b, wherein Q 采出 is the crude argon production flow, L is the total air flow corresponding to the load of the air separation device, k is the load-flow ratio coefficient, and b is the correction flow constant.

[0099] In the above technology, when the load changes, Q 采出 is adjusted linearly with L, and at the same time, the PID dynamically compensates the influence of temperature and pressure fluctuations on the oxygen content. For example:

[0100] When the load of the air separation device is , Q 采出 =0.00666×300000+200=2198Nm³ / h is calculated.

[0101] If the actual detection , and at the same time, the rectification temperature in the sensitive area of the crude argon column is unchanged, the PID output maintains the current production;

[0102] If or the rectification temperature in the sensitive area of the crude argon column increases, the PID output of the cascade control loop corrects to reduce the production, and quickly reduces the oxygen content to below 1 ppm.

[0103] S05, dynamically adjusting the temperature set value of the sensitive area of the medium-pressure column, the low-pressure column and the crude argon column according to the load change, so that the working condition of the rectification column automatically tracks the load change to always maintain the optimal state.

[0104] Specifically, the dynamic adjustment referred to above specifically includes:

[0105] When the load of the air separation device increases, the temperature set value of the sensitive area of the low-pressure column is reduced by 0.1-0.5°C from the design value -188°C, and the column pressure is set to 1.13atm±0.02atm;

[0106] When the load of the air separation device decreases, the temperature set value of the sensitive area of the low-pressure column is increased by 0.1-0.5°C from the design value -188°C, and the column pressure is adjusted to 1.13atm±0.02atm.

[0107] The low-pressure column gas phase oxygen concentration threshold (30% ± 1%): the design value of the low-pressure column sensitive region gas phase oxygen concentration is 30% by gas-liquid equilibrium calculation, and the temperature fluctuation ± 0.3℃ will cause the oxygen concentration to change ≥1%, and when the DCS system calculates the gas phase oxygen concentration deviates from 30% (such as the detection value is 31% or 29%), the reflux ratio or the feed quantity is automatically adjusted to make the oxygen concentration return to the threshold range.

[0108] The medium-pressure column bottom liquid phase oxygen concentration threshold (41% ± 2%): the calculated value of the liquid phase oxygen concentration of the oxygen-rich liquid air at the bottom of the medium-pressure column is 41%, which directly affects the low-pressure column feed composition. A fluctuation range of ± 2% is allowed, considering the cumulative error of the medium-pressure column operating pressure (460 kPa) and temperature detection (-176℃ ± 1℃). The liquid phase oxygen concentration is verified by the medium-pressure column bottom temperature detection (-176℃ ± 1℃) and column pressure calculation (4.54 atm), and if it exceeds 41% ± 2%, the medium-pressure column operating parameters (such as the amount of contaminated liquid nitrogen extraction or the amount of liquid nitrogen extraction) are adjusted.

[0109] Example Two

[0110] The embodiment of the present application provides a non-transitory computer readable storage medium, at least one instruction or at least one program is stored in the non-transitory computer readable storage medium, the at least one instruction or the at least one program is loaded and executed by a processor to realize the steps of:

[0111] The temperature and column pressure data of the sensitive region of the rectifying column in the air separation device are detected in real time by the DCS system, and the sensitive region is the packing section with the largest concentration gradient change in the rectifying column;

[0112] The obtained real-time temperature and column pressure data of the sensitive region of the rectifying column are combined with the preset gas-liquid equilibrium function relationship to dynamically calculate the gas phase and liquid phase component concentration of the sensitive region of the rectifying column;

[0113] The calculated gas phase and liquid phase component concentration is compared with the design value, and the gas phase and liquid phase component concentration is controlled in the set threshold range by adjusting the reflux ratio or the feed quantity of the rectifying column;

[0114] The oxygen content in the crude argon product at the top of the crude argon column is monitored in real time, and when the oxygen content is ≤1ppm, the maximum crude argon extraction amount is maximized to prevent the argon component from flowing back to the low-pressure column stripping section;

[0115] The temperature set value of the sensitive region of the medium-pressure column, the low-pressure column and the crude argon column is dynamically adjusted according to the load change, so that the working condition of the rectifying column automatically tracks the load change to always maintain the optimal state.

[0116] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by a computer program instructing relevant hardware, and the computer program can be stored in a non-volatile computer readable storage medium, and when the computer program is executed, the processes of the above-mentioned embodiments of the methods can be included. Wherein, any reference to memory, storage, database or other medium used in each embodiment provided by the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM) and the like.

[0117] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of functional units and modules is exemplified, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the above-described functions.

[0118] Embodiment three

[0119] The embodiment of the present application provides an electronic device, comprising a processor and a memory, at least one instruction or at least one program is stored in the memory, the at least one instruction or the at least one program is loaded and executed by the processor to realize the steps of:

[0120] The temperature and tower pressure data of the sensitive area of the rectifying tower are detected in real time through the DCS system, and the sensitive area is the packing section with the largest concentration gradient change in the rectifying tower;

[0121] The obtained real-time temperature and tower pressure data of the sensitive area of the rectifying tower are combined with the preset gas-liquid equilibrium function relationship to dynamically calculate the gas phase and liquid phase component concentrations of the sensitive area of the rectifying tower;

[0122] The calculated gas phase and liquid phase component concentrations are compared with the design values, and the gas phase and liquid phase component concentrations are controlled within the set threshold range by adjusting the reflux ratio or feed quantity of the rectification column;

[0123] The oxygen content in the crude argon product at the top of the crude argon column is monitored in real time, and when the oxygen content is ≤1 ppm, the crude argon production is maximized to prevent the argon component from backflowing to the low-pressure column stripping section;

[0124] The temperature set values of the sensitive regions of the medium-pressure column, the low-pressure column and the crude argon column are dynamically adjusted according to load changes, so that the working conditions of the rectification columns automatically track the load changes to always maintain an optimal state.

[0125] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. An optimization control strategy for low-temperature distillation of an air fractionation distillation tower based on sensitivity analysis, characterized in that: The strategy includes the following steps: S01. Real-time detection of temperature and tower pressure data of a sensitive area of ​​a distillation tower in an air separation unit through a DCS system. The sensitive area is a packing section with the largest concentration gradient change in the distillation tower. S02. Dynamically calculate the concentrations of gas and liquid components in the sensitive areas of the distillation tower using the acquired real-time temperature and tower pressure data of the sensitive areas of the distillation tower in combination with a preset gas-liquid equilibrium function relationship; S03. Comparing the calculated concentrations of the gas phase and liquid phase components with the designed values, and controlling the concentrations of the gas phase and liquid phase components within a set threshold range by adjusting the reflux ratio or feed rate of the distillation column; S04. Real-time monitoring of the oxygen content in the crude argon product at the top of the crude argon column. When the oxygen content is ≤1 ppm, maximizing the crude argon production to prevent the argon component from flowing back into the stripping section of the low-pressure column. S05. Dynamically adjust the temperature setting values ​​of sensitive areas of the medium-pressure tower, low-pressure tower, and crude argon tower according to load changes, so that the distillation tower operating conditions automatically track the load changes to always maintain the optimal state; The gas-liquid equilibrium function relationship in step S02 includes the following formula: Oxygen component balance formula: ； Nitrogen component balance formula: ； Argon composition equilibrium formula: ； Among them, T is the thermodynamic temperature, t is the detection temperature, P is the distillation tower pressure, and the liquid and gas phase concentrations satisfy: ； Yo2: oxygen content in the gas phase of the packing section corresponding to the distillation temperature of the distillation tower; Yn2: Nitrogen content in the gas phase of the packing section corresponding to the distillation temperature of the distillation tower; Yar: Argon content in the gas phase of the packing section corresponding to the distillation temperature of the distillation tower; xo2: oxygen content in the liquid phase of the packing section corresponding to the distillation temperature of the distillation tower; xn2: nitrogen content in the liquid phase of the packing section corresponding to the distillation temperature of the distillation tower; xar: argon content in the liquid phase of the packing section corresponding to the distillation temperature of the distillation column; Psn: Nitrogen component saturation vapor pressure presents a single-valued function relationship with distillation temperature, unit: atm; Pso: The saturated vapor pressure of oxygen component presents a single-valued function relationship with the distillation temperature, unit: atm; Par: The saturated vapor pressure of argon component presents a single-valued function relationship with the distillation temperature, unit: atm; The dynamic adjustment in step S05 specifically includes: When the load of the air separation unit increases, the temperature setting value of the sensitive area of ​​the low-pressure tower is reduced by 0.1-0.5℃ from the design value of -188℃, and the tower pressure is set to 1.13atm±0.02atm; When the load of the air separation unit decreases, the temperature setting value of the sensitive area of ​​the low-pressure tower is increased by 0.1-0.5℃ from the design value of -188℃, and the tower pressure is adjusted to 1.13atm±0.02atm simultaneously; The method for calculating the tower pressure data in step S01 includes: S11, collect the top pressure P of the distillation tower in real time through the DCS system 顶 and the bottom pressure P 底 , calculate the arithmetic mean of the two as the distillation tower pressure P, then the formula is as follows: P= (P 顶 +P 底 ) / 2; S12. The pressure difference between the top and bottom of the tower must meet the following requirements: If the pressure difference exceeds the limit, the DCS system will trigger an alarm and automatically adjust the distillation tower operating parameters to restore the pressure difference to the allowable range.

2. The optimization control strategy for low-temperature distillation of an air fractionation distillation tower based on sensitivity analysis according to claim 1, characterized in that: The method for dividing the sensitive area of ​​the middle distillation tower in step S03 includes: The sensitive area of ​​the low-pressure tower is located in the gas-liquid distributor area above the packing section corresponding to the oxygen-enriched air feed inlet from the crude argon condenser. The temperature gradient change rate of the corresponding packing section is ≥5℃ / m, and the temperature setting value is -188℃±0.3℃; The sensitive area of ​​the medium-pressure tower is located in the oxygen-rich liquid air pipeline at the bottom of the tower, and the detection temperature is -176℃±1℃; The sensitive area of ​​the crude argon tower is located in the middle packing section, and the temperature setting value is -183.6℃±0.5℃.

3. The optimization control strategy for low-temperature distillation of an air fractionation distillation tower based on sensitivity analysis according to claim 2, characterized in that: In the sensitive area of ​​the distillation section of the low-pressure tower, when the concentration of the gaseous argon component is ≤2%, it is simplified to an oxygen and nitrogen binary distillation model, and the calculation of the argon component is ignored. At this time, xar=0, yar=0, xo2+xn2=1, yo2+yn2=1.

4. The optimization control strategy for low-temperature distillation of an air fractionation distillation tower based on sensitivity analysis according to claim 1, characterized in that: The step S03 further includes setting an oxygen concentration threshold, which includes: The design value of gas-phase oxygen concentration in the sensitive area of ​​the low-pressure tower is 30%±1%; The design value of liquid oxygen concentration at the bottom of the medium-pressure tower is 41%±2%.

5. The optimization control strategy for low-temperature distillation of an air fractionation distillation tower based on sensitivity analysis according to claim 1, characterized in that: The control of the oxygen content in the crude argon product at the top of the crude argon column in step S04 is achieved by a PID algorithm, and the linear relationship between its set value and the load of the air separation unit is: Q 采出 =k·L+b, where Q 采出 is the crude argon production flow rate, L is the load percentage of the air separation unit, k is the load-flow ratio coefficient, and b is the basic flow constant.

6. 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 steps of optimizing the control strategy of the low-temperature distillation of the air fractionation distillation tower based on sensitivity analysis as described in any one of claims 1 to 5.

7. An electronic device, characterized in that: The method comprises 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 steps of the low-temperature distillation optimization control strategy of the air fractionation distillation tower based on sensitivity analysis as described in any one of claims 1 to 5.

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