Rectifying tower control method, terminal equipment and readable storage medium

Abstract

The invention provides a rectifying tower control method, terminal equipment and a readable storage medium, and belongs to the technical field of chemical separation, the control method comprises the following steps: determining a control variable and a controlled variable in a current working state based on a comparison result of a current measured value of a working parameter of a rectifying tower and a target range; when it is determined that a difference exists between the current measured value of the control variable and the target range of the control variable, a target adjustment value of the controlled variable is determined based on a PID algorithm; and adjusting the rectifying tower according to the target adjusting value of the controlled variable. Wherein the control variable is at least one of the working parameters of the rectifying tower, and the controlled variable is at least one of the tower bottom steam valve opening degree, the inlet valve opening degree of the rectifying tower, the power of a stripping section heat preservation sleeve, the power of a rectifying section heat preservation sleeve and the reflux ratio of the rectifying tower. Through the method provided by the invention, the accurate rectifying tower adjusting effect can be achieved, the control flow of the rectifying tower is obviously optimized, the working efficiency is improved, and the operation cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical separation, and in particular to a distillation tower control method, a terminal device and a computer-readable storage medium. Background Art

[0002] The chemical separation process is one of the cores in chemical engineering. Among them, the distillation tower is widely used in the chemical separation process. Its principle is to use the difference in relative volatility between different substances to complete the separation of components. The working state of the distillation tower is very important for the successful separation of substances. In the process of operating the distillation tower, many working parameters are involved, such as temperature, pressure, flow rate, etc. In order to ensure the smooth operation of the distillation tower, these parameters need to be monitored and the corresponding equipment needs to be debugged to make these parameters reach the ideal value. Usually, the monitoring and debugging of the working parameters of the distillation tower are completed manually.

[0003] However, with the development of the chemical industry, the requirements for distillation technology and product quality are becoming higher and higher. The current manual monitoring and debugging methods are becoming less and less suitable for the new stage of chemical industry development. Manual adjustment will inevitably lead to adjustment lag, reliance on staff experience, lack of unified standards and other defects, which will have an adverse effect on the overall energy consumption, control optimization and product purity of the distillation tower.

[0004] In order to solve the adverse effects caused by manually adjusting the working parameters of the distillation tower, relevant scholars proposed to monitor, debug and feedback the working parameters of the distillation tower through automated programs, so as to realize the automated control of the distillation tower. The automated control of the distillation tower can not only optimize the control effect of the distillation tower and reduce the delayed debugging of parameters, but also improve the purity of the product, reduce the output of unqualified products, and realize the automated control of the entire distillation tower. In addition, automated control can also realize the interconnected control of multiple variables of the distillation tower that is difficult to achieve through manual operation. By setting the priority control rights of different variables, determining the main control variables and auxiliary control variables, the purpose of precise control of the distillation tower can be achieved.

[0005] However, the current automated control method for distillation towers can control fewer parameter variables, and the overall control of the distillation tower is very limited. For example, a Chinese patent document with a publication date of November 29, 2022 and a publication number of CN115400444A proposes a distillation tower control method, which includes: obtaining the current bottom liquid level and the current bottom temperature of the distillation tower in real time; controlling the operating state of the distillation tower according to the current bottom liquid level, the current bottom temperature, and the preset target distillation tower information. The invention can better control the bottom temperature and liquid level and realize automatic control of the distillation tower. However, this method only controls the relevant parameters through a single variable, and the accuracy is not very high. At the same time, the number of controlled variables is small, and only the bottom liquid level and temperature are involved, and the overall control of the distillation tower is limited. Summary of the invention

[0006] In view of the technical problem that the automation control method of the distillation tower in the prior art has very limited control over the whole distillation tower, the present invention provides a distillation tower control method. This method can set different control processes for the distillation tower according to different working states of the distillation tower, and can effectively adapt to the working rules of the distillation tower itself.

[0007] To achieve the above-mentioned purpose, the first aspect of the present invention provides a distillation tower control method, the control method comprising the following steps: obtaining the current measured value of the distillation tower working parameter within the current sampling period; judging the current working state based on the comparison result between the current measured value of the distillation tower working parameter and the target range; determining the control variable and the controlled variable under the current working state of the distillation tower; determining the target adjustment value of the controlled variable based on the PID algorithm when it is determined that there is a difference between the current measured value of the control variable and the target range, and adjusting the controlled variable of the distillation tower according to the target adjustment value of the controlled variable; and adjusting the controlled variable of the distillation tower according to the target adjustment value of the controlled variable. The distillation tower; directly enters the next sampling cycle when it is determined that there is no difference between the current measured value of the control variable and the target range of the control variable; wherein the operating parameters of the distillation tower include: bottom liquid level, bottom temperature, stripping section temperature, distillation section temperature, top product composition and top extraction flow rate; the controlled variable is at least one of the distillation tower operating parameters; the controlled variable includes main controlled variables, and the main controlled variables are at least one of the opening of the bottom steam valve, the opening of the inlet valve of the distillation tower, the power of the stripping section insulation jacket, the power of the distillation section insulation jacket and the reflux ratio of the distillation tower; the target range may include a target upper limit value and a target lower limit value.

[0008] In an exemplary embodiment of the present invention, the controlled variable may further include: a secondary controlled variable, which is at least one of the set temperature of the preheater, the opening of the inlet valve of the distillation tower, and the opening of the outlet valve of the tower bottom.

[0009] In an exemplary embodiment of the present invention, the current working state of the distillation tower is judged based on the comparison result of the current measured value of the working parameter of the distillation tower with the target range, which may include: when it is determined that the current measured value of the bottom liquid level is less than the target lower limit value of the bottom liquid level, determining that the current working state is the feeding stage; when it is determined that the current measured value of the bottom liquid level is greater than the target lower limit value of the bottom liquid level, determining that the current working state is the heating stage; when it is determined that the current measured value of the top production flow rate is greater than the target lower limit value of the top production flow rate, determining that the current working state is the production stage.

[0010] In an exemplary embodiment of the present invention, determining the control variables and controlled variables under the current working state may include: determining the control variable of the feeding stage as the bottom temperature, and determining the main controlled variable corresponding to the bottom temperature of the feeding stage as the opening of the bottom steam valve.

[0011] In an exemplary embodiment of the present invention, the secondary controlled variable corresponding to the tower bottom temperature in the feeding stage can be determined as the set temperature of the preheater and the opening degree of the inlet valve of the distillation tower.

[0012] In an exemplary embodiment of the present invention, the determination of the control variables and controlled variables under the current working state may also include: determining the control variables in the heating stage as the bottom liquid level, the bottom temperature, the stripping section temperature and the rectifying section temperature; determining the main controlled variable corresponding to the bottom liquid level in the heating stage as the opening of the inlet valve of the rectifying tower; determining the main controlled variable corresponding to the stripping section temperature in the heating stage as the opening of the bottom steam valve and the power of the stripping section insulation jacket; determining the main controlled variable corresponding to the rectifying section temperature in the heating stage as the opening of the bottom steam valve and the power of the rectifying section insulation jacket.

[0013] In an exemplary embodiment of the present invention, the secondary controlled variable corresponding to the bottom liquid level in the heating stage can be determined as the opening of the bottom outlet valve; and, the secondary controlled variable corresponding to the bottom temperature in the heating stage can be determined as the set temperature of the preheater and the opening of the inlet valve of the distillation tower.

[0014] In an exemplary embodiment of the present invention, the determination of the control variables and controlled variables under the current working state may also include: determining the control variables in the extraction stage as the bottom liquid level, bottom temperature, stripping section temperature, rectifying section temperature, top product composition and top extraction flow rate; determining the main controlled variable corresponding to the bottom liquid level in the extraction stage as the inlet valve opening of the distillation tower; determining the main controlled variable corresponding to the stripping section temperature in the extraction stage as the power of the stripping section insulation jacket; determining the main controlled variable corresponding to the rectifying section temperature in the extraction stage as the power of the rectifying section insulation jacket; determining the main controlled variable corresponding to the top product composition in the extraction stage as the reflux ratio of the distillation tower; and determining the main controlled variable corresponding to the top extraction flow rate in the extraction stage as the opening of the bottom steam valve.

[0015] In an exemplary embodiment of the present invention, the secondary controlled variable corresponding to the bottom liquid level in the extraction stage can be determined as the outlet valve opening of the bottom; and, the secondary controlled variable corresponding to the bottom temperature in the extraction stage can be determined as the set temperature of the preheater and the inlet valve opening of the distillation tower.

[0016] In an exemplary embodiment of the present invention, the calculation formula of the PID algorithm may be:

[0017] f(x)=f(x-1)+K p [L(x)-L(x-1)]+K i L(x)+K d [L(x)-2L(x-1)+L(x-2)];

[0018] Where f(x) is the target adjustment value of the controlled variable, L(x) is the difference between the current measured value of the controlled variable and the target range in the current sampling period, L(x-1) is the difference between the current measured value of the controlled variable and the target range in the previous sampling period, L(x-2) is the difference between the current measured value of the controlled variable and the target range in the previous two sampling periods, and K p is the proportionality coefficient, K i is the integration coefficient, K d is the differential coefficient.

[0019] In an exemplary embodiment of the present invention, when the current measured value of the controlled variable is less than the target lower limit value of the controlled variable, or when the current measured value of the controlled variable is greater than the target upper limit value of the controlled variable, the proportional coefficient of the main controlled variable may be determined as the set initial value;

[0020] When the current measured value of the control variable is greater than the target lower limit value of the control variable and less than the target upper limit value of the control variable, the proportional coefficient of the main controlled variable can be determined as the product of the set initial value and the limiting factor;

[0021] The calculation formula of the limiting factor is:

[0022]

[0023] Where θ is the limiting factor, L0 is the current measured value of the control variable, L1 is the target lower limit of the control variable, L2 is the target upper limit of the control variable, k is a custom constant, and 0.2 <k<1。

[0024] In an exemplary embodiment of the present invention, the proportional coefficient of the secondary controlled variable may be determined as the product of the set initial value and the relative coefficient, and the relative coefficient is set to a value of 0.2 to 0.9.

[0025] A second aspect of the present invention provides a terminal device, which includes a processor and a memory, wherein the memory stores at least one computer program, and the at least one computer program is loaded and executed by one or more of the above processors to enable the terminal device to implement the above-mentioned distillation tower control method.

[0026] A third aspect of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores at least one program code, and the program code is loaded and executed by a processor to enable a computer to implement the above-mentioned distillation tower control method.

[0027] Through the technical solution provided by the present invention, the present invention has at least the following technical effects:

[0028] (1) The distillation tower control method of the present invention sets different control variables and controlled variables for adjusting the control variables according to different working states. By adjusting the controlled variables to target values, the working parameters of the distillation tower (such as tower bottom temperature, tower bottom liquid level, etc.) are accurately controlled, which not only realizes the automatic control of the distillation tower, but also improves the working efficiency and avoids safety accidents caused by manual operation errors;

[0029] (2) Based on the use of the main controlled variables to adjust the control variables under different working conditions, the present invention adds secondary controlled variables to assist in adjusting the control variables, which can improve the control accuracy of the working parameters of the distillation tower and enhance the overall control strength of the distillation tower;

[0030] (3) The distillation tower control method of the present invention sets a multivariable control process with different priorities according to different working states, which can realize the mutual linkage control among multiple variables of the distillation tower, making the entire control process more accurate and efficient;

[0031] (4) The present invention can significantly optimize the control process of the distillation tower, improve work efficiency and reduce operating costs by establishing a mediation network of different levels between each control quantity and the controlled variable;

[0032] (5) The present invention can obtain the working parameters of the distillation tower in real time, and use a computer program to adjust the various parameters in the distillation tower in real time according to the preset target values, thereby realizing automatic control of the entire distillation tower, which can effectively improve the working efficiency of the distillation tower and optimize energy consumption and product quality;

[0033] (6) The control method for the distillation tower adopted by the present invention has relatively low requirements on the distillation tower itself, can be applied to various types of distillation equipment, has a wide range of applications, and the control method is reliable.

[0034] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0036] Figure 1 A schematic flow chart of a distillation tower control method provided in the first embodiment of the present invention;

[0037] Figure 2 A schematic diagram of the structure of a distillation tower and a terminal device provided for the second embodiment of the present invention;

[0038] Figure 3 A schematic flow chart of a distillation tower control method provided in accordance with a second embodiment of the present invention;

[0039] Figure 4 A schematic diagram of the control logic of a distillation column under different working conditions provided by the second embodiment of the present invention;

[0040] Figure 5 A schematic diagram of the structure of a terminal device provided in the third embodiment of the present invention.

[0041] Description of Reference Numerals

[0042] 1-raw material tank, 2-raw material preheater, 3-distillation tower, 4-condenser, 5-reboiler, 6-reflux ratio controller, 7-distillation section insulation cover, 8-stripping section insulation cover, 9-gas chromatograph, 10-bottom level gauge, 11-bottom thermometer, 12-stripping section thermometer, 13-distillation section thermometer, 14-tower top thermometer, 15-tower top outlet flowmeter, 16-feed inlet valve, 17-bottom outlet valve, 18-steam valve, 19-terminal equipment, 1901-processor, 1902-memory. DETAILED DESCRIPTION

[0043] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0045] In the present invention, unless otherwise specified, the directional words used, such as "upper, lower, top, bottom", are usually used to describe the relative positional relationship of the components in terms of the directions shown in the drawings or in terms of the vertical, perpendicular or gravity directions. "First", "second", etc. are only used for the convenience of description and distinction, and cannot be understood as indicating or implying relative importance.

[0046] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installation", "connection", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a direct connection, or an indirect connection; it can be a wired connection, or a wireless connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0047] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0048] Embodiment 1

[0049] Please refer to Figure 1 The first embodiment of the present invention provides a distillation tower control method, the method comprising the following steps:

[0050] Step S101: in the current sampling period, obtain the current measured value of the distillation tower operating parameter.

[0051] It should be noted that distillation is a process of separating components in a mixture by utilizing their different volatilities. A typical distillation device is a continuous distillation device, which consists of a distillation tower, a reboiler, a condenser, etc. The distillation tower provides vapor-liquid two-phase contact for interphase mass transfer. The condenser at the top of the tower partially condenses the vapor, and part of the condensate is returned to the top of the tower as reflux liquid. The remaining distillate is the top product of the tower.

[0052] The internal structure of the distillation tower can be divided into three main parts: the top part, the tower body part and the tower bottom part, and the distillation tower generally has a feed port, a top discharge port and a tower bottom discharge port. Among them, the feed port is located in the middle of the tower body, and the preheater is connected to the feed port for preheating the raw liquid. The tower body part consists of a distillation section and a stripping section. The distillation section is above the feed port, from the feed plate to the top of the tower, and the stripping section is below the feed port, from the feed plate to the bottom of the tower. After the preheated raw liquid with a certain temperature and pressure enters the distillation tower, the volatile light components are gradually concentrated in the distillation section to form the product (distillate) at the top of the tower; while the non-volatile heavy components are gradually concentrated in the stripping section to form the product (residue) in the tower bottom. The tower bottom part is equipped with a reboiler to reheat the liquid descending from the tower body. The top of the tower is equipped with a condenser and a reflux ratio controller. The condenser is used to cool the top distillate from steam to liquid, and the reflux ratio controller is used to adjust the reflux ratio. The reflux ratio refers to the ratio of the amount of liquid refluxed into the tower from the top to the amount of top product. It is an important control parameter for distillation operation, and its change affects the separation effect and energy consumption of distillation operation.

[0053] Therefore, in order to continuously optimize the separation effect of the distillation tower, improve the purity of the product, and reduce the output of unqualified products, the distillation tower working parameters that need to be monitored and debugged may include the bottom liquid level, bottom temperature, stripping section temperature, distillation section temperature, top product composition and top extraction flow rate.

[0054] Step S102: based on the comparison result between the current measured value of the operating parameter of the distillation tower and the target range, the current operating state of the distillation tower is determined.

[0055] Generally speaking, for each distillation tower working parameter, an expected target range should be set in advance. When the value of the distillation tower working parameter is within the preset target range, a relatively excellent separation effect of the distillation tower can be achieved. Different distillation tower working parameters can indirectly reflect the operating status of the distillation tower. Therefore, by comparing the current measured value of the distillation tower working parameter with the size of the target range, the current working status of the distillation tower can be determined.

[0056] For example, the current working state of the distillation tower can be determined by comparing the current measured values ​​of the tower bottom liquid level and the tower top extraction flow rate with the size of the target range. A target upper limit value and a target lower limit value can be preset for both the tower bottom liquid level and the tower top extraction flow rate, and the interval range formed by the target upper limit value and the target lower limit value is determined as the target range of the corresponding working parameter.

[0057] When the current measured value of the bottom liquid level is less than the target lower limit of the bottom liquid level, it can be judged that the current working state of the distillation tower is the feeding stage; when the current measured value of the bottom liquid level is greater than the target lower limit of the bottom liquid level, it can be judged that the current working state of the distillation tower is the heating stage; when the current measured value of the top extraction flow rate is greater than the target lower limit of the top extraction flow rate, it can be judged that the current working state of the distillation tower is the extraction stage.

[0058] Step S103: Determine the control variable and the controlled variable in the current working state.

[0059] Here, the control variable refers to one or more operating parameters that can affect the operating effect of the distillation tower under the current working state. In other words, the control variable is one or more parameters selected from multiple distillation tower operating parameters based on the current working state that can participate in debugging the operating effect of the distillation tower.

[0060] The controlled variable refers to one or more distillation tower adjustment parameters that can affect the numerical value of the control variable. By adjusting the size of these distillation tower adjustment parameters, the distillation tower operating parameters can be adjusted from the current measured value to the target range.

[0061] It should be noted that the regulating parameters of the distillation tower refer to the parameters monitored by the regulating equipment of the distillation tower, and the regulating equipment of the distillation tower refers to the equipment connected to the outlets and inlets of the distillation tower and capable of monitoring the physical properties of the materials entering and leaving the distillation tower. For example, the regulating equipment of the distillation tower can be a thermometer installed at the top of the tower, the distillation section, the stripping section and the bottom of the tower, or a flow meter and a product detector installed at the discharge port of the top of the tower, or a valve installed at the feed port, the discharge port of the top of the tower and the discharge port of the bottom of the tower.

[0062] Step S104A: when it is determined that there is a difference between the current measured value of the controlled variable and the target range of the controlled variable, a target adjustment value of the controlled variable is determined based on a PID algorithm.

[0063] Here, the difference between the current measured value of the control variable and the target range of the control variable can refer to the difference between the current measured value of the control variable and the target upper limit value of the control variable; it can also refer to the difference between the current measured value of the control variable and the target lower limit value of the control variable.

[0064] Step S104B: When it is determined that there is no difference between the current measured value of the control variable and the target range, directly enter the next sampling cycle.

[0065] Step S105: adjusting the distillation tower according to the target adjustment value of the controlled variable.

[0066] Through the above technical solution, the working parameters of the distillation tower are collected at regular intervals, and the control variables under different working conditions are determined. Then, the difference between the current measured value of the control variable and the target range (for example, the target upper limit value) is judged. If it is judged that there is a difference, the controlled variable is adjusted and controlled through the control logic, and the control logic is implemented by the PID algorithm. If it is judged that there is no difference, it directly enters the next sampling cycle; repeat the above control process to keep the control variable stable within the target range.

[0067] In this embodiment, the controlled variables may include main controlled variables, which are at least one of the opening of the bottom steam valve, the opening of the inlet valve of the distillation tower, the power of the insulation jacket of the distillation section, the power of the insulation jacket of the distillation section and the reflux ratio of the distillation tower.

[0068] Furthermore, in a possible implementation, the controlled variable may also include a secondary controlled variable, which is at least one of the set temperature of the preheater, the opening of the inlet valve of the distillation tower, and the opening of the outlet valve of the tower bottom. That is, when the controlled variable has an auxiliary controlled controlled variable, the auxiliary controlled controlled variable is used as a secondary controlled variable and adjusted together with the main controlled variable.

[0069] Furthermore, in a possible implementation, when it is determined that the current working state of the distillation tower is the feeding stage, the control variable of the feeding stage can be determined as the bottom temperature, and the main controlled variable corresponding to the bottom temperature of the feeding stage can be determined as the opening of the bottom steam valve.

[0070] In addition, the secondary controlled variables corresponding to the tower bottom temperature in the feeding stage can also be determined as the set temperature of the preheater and the opening of the inlet valve of the distillation tower.

[0071] Furthermore, in a possible implementation, when it is determined that the current working state of the distillation tower is a heating stage, the control variables of the heating stage may be determined as the bottom liquid level, the bottom temperature, the stripping section temperature and the distillation section temperature.

[0072] The main controlled variable corresponding to the tower bottom liquid level during the temperature rise stage can be determined as the inlet valve opening of the distillation tower. The main controlled variable corresponding to the stripping section temperature during the temperature rise stage can be determined as the bottom steam valve opening and the power of the stripping section insulation jacket. The main controlled variable corresponding to the distillation section temperature during the temperature rise stage can be determined as the bottom steam valve opening and the power of the distillation section insulation jacket.

[0073] In addition, the secondary controlled variable corresponding to the tower bottom liquid level in the heating stage can be determined as the tower bottom outlet valve opening. The secondary controlled variable corresponding to the tower bottom temperature in the heating stage can be determined as the set temperature of the preheater and the inlet valve opening of the distillation tower.

[0074] Furthermore, in a possible implementation, when it is determined that the current working state of the distillation tower is the extraction stage, the control variables of the extraction stage can be determined as the bottom liquid level, the bottom temperature, the stripping section temperature, the distillation section temperature, the top product composition and the top extraction flow rate.

[0075] The main controlled variable corresponding to the bottom liquid level in the extraction stage can be determined as the opening of the inlet valve of the distillation tower. The main controlled variable corresponding to the temperature of the stripping section in the extraction stage can be determined as the power of the insulation jacket of the stripping section. The main controlled variable corresponding to the temperature of the distillation section in the extraction stage can be determined as the power of the insulation jacket of the distillation section. The main controlled variable corresponding to the composition of the top product in the extraction stage can be determined as the reflux ratio of the distillation tower. The main controlled variable corresponding to the top extraction flow in the extraction stage can be determined as the opening of the bottom steam valve.

[0076] In addition, the secondary controlled variable corresponding to the tower bottom liquid level in the extraction stage can be determined as the tower bottom outlet valve opening. Also, the secondary controlled variable corresponding to the tower bottom temperature in the extraction stage can be determined as the set temperature of the preheater and the inlet valve opening of the distillation tower.

[0077] Furthermore, the calculation formula of the PID algorithm can be shown as follows (1).

[0078] f(x)=f(x-1)+K p [L(x)-L(x-1)]+K i L(x)+K d [L(x)-2L(x-1)+L(x-2)] (1)

[0079] In formula (1), f(x) is the target adjustment value of the controlled variable, L(x) is the difference between the current measured value of the controlled variable and the target range in the current sampling period, L(x-1) is the difference between the current measured value of the controlled variable and the target range in the previous sampling period, L(x-2) is the difference between the current measured value of the controlled variable and the target range in the previous two sampling periods, and K p is the proportionality coefficient, K i is the integration coefficient, K d is the differential coefficient.

[0080] It should be noted that the proportionality coefficient K in the above formula (1) is p Adjustments can be made based on the comparison between the current measured value of the control variable and the target range.

[0081] Specifically, when the current measured value of the controlled variable is less than the target lower limit value of the controlled variable, the proportional coefficient of the main controlled variable is determined as the set initial value.

[0082] When the current measured value of the controlled variable is greater than the target upper limit value of the controlled variable, the proportional coefficient of the main controlled variable is determined as the set initial value.

[0083] When the current measured value of the control variable is greater than the target lower limit value of the control variable and less than the target upper limit value of the control variable, the proportional coefficient of the main controlled variable is determined as the product of the set initial value and the limiting factor. The calculation formula of the limiting factor is shown in the following formula (2).

[0084]

[0085] In formula (2), θ is the limiting factor, L0 is the current measured value of the control variable, L1 is the target lower limit value of the control variable, L2 is the target upper limit value of the control variable, k is a custom constant, and 0.2 <k<1。

[0086] When there is an auxiliary controlled variable in the control variable, the proportional coefficient of the secondary controlled variable can be determined as the product of the set initial value and the relative coefficient, and the value of the relative coefficient is 0.2 to 0.9.

[0087] Furthermore, in a possible implementation manner, the sampling period of the distillation tower operating parameters may be 0.25 to 1 min, with 3 to 6 samples being taken each time, and the average value is taken as the sampling result and input into the computer.

[0088] It should be noted that Figure 1 The flow diagram of the distillation tower control method provided in this embodiment. It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but the steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of the steps, and the steps can be executed in other orders. Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0089] In addition, the implementation environment of this embodiment includes at least one terminal and a server, and the method is executed on the terminal or the server, respectively. The terminal and the server can be connected in communication to realize the interactive transmission of information. For example, the distillation tower control method of this embodiment can be applied to the server, and the real-time measurement data of the distillation tower operating parameters of this embodiment is stored in the terminal, and the server can receive the real-time measurement data of the distillation tower operating parameters sent by the terminal.

[0090] Among them, the terminal can be any electronic product that can interact with the user through one or more methods such as keyboard, touchpad, touch screen, voice interaction, etc., such as PC (Personal Computer), PPC (Pocket Personal Computer), tablet computer, etc.

[0091] The server can be a single server or a server cluster composed of multiple servers. It can also be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN (Content Delivery Network), as well as big data and artificial intelligence platforms.

[0092] Embodiment 2

[0093] Taking an atmospheric distillation device for preparing high-purity acrylonitrile as an example, a second embodiment of the present invention provides a distillation tower control method for an atmospheric distillation device for preparing high-purity acrylonitrile.

[0094] Figure 2 The schematic diagram of the connection between a normal pressure distillation device for removing trace impurities from raw materials to prepare high-purity acrylonitrile and a terminal device is shown, wherein a control program for implementing a distillation tower control method is stored in the terminal device. Figure 2 As shown, the distillation equipment includes a raw material tank 1, a raw material preheater 2, a distillation tower 3, a condenser 4, a reboiler 5, a reflux ratio controller 6, a distillation section insulation jacket 7, a stripping section insulation jacket 8, a gas chromatograph 9, a tower bottom liquid level gauge 10, a tower bottom thermometer 11, a stripping section thermometer 12, a distillation section thermometer 13, a tower top thermometer 14, a tower top outlet flowmeter 15, a feed inlet valve 16, a tower bottom outlet valve 17 and a steam valve 18. Among them, the gas chromatograph 9, the tower bottom liquid level gauge 10, the tower bottom thermometer 11, the stripping section thermometer 12, the distillation section thermometer 13, the tower top thermometer 14 and the tower top outlet flowmeter 15 can transmit the monitored data to the terminal device 19, and the terminal device 19 automatically controls the reflux ratio controller 6, the feed inlet valve 16, the tower bottom outlet valve 17 and the steam valve 18 according to the signal and the control program.

[0095] The process flow of high-purity acrylonitrile distillation is as follows: the acrylonitrile raw material is preheated from the raw material tank through the raw material preheater and then enters the tower body from the middle, and is heated by steam in the tower bottom. After being heated to a certain temperature, it begins to vaporize and enters the tower top for condensation. When the distillation rate at the top of the tower reaches the target value, the purity of the distillate at the top of the tower is analyzed by a gas chromatograph, and the product is extracted after the reflux ratio is adjusted to obtain a product that meets the requirements.

[0096] like Figure 3 As shown, the automated control process of high-purity acrylonitrile distillation may specifically include the following steps.

[0097] Step S201: Run the control program on the terminal device.

[0098] Step S202: setting the target range of the distillation tower operating parameters.

[0099] Specifically, the target lower limit value and target upper limit value of the distillate purity of the gas chromatograph, the target lower limit value and target upper limit value of the bottom liquid level, the target lower limit value and target upper limit value of the bottom temperature, the target lower limit value and target upper limit value of the stripping section temperature, the target lower limit value and target upper limit value of the rectification section temperature, and the target lower limit value and target upper limit value of the top outlet flow rate are set.

[0100] Step S203: monitor the operating parameters of the distillation tower according to the sampling period, and determine the control variables under the current working state according to the current measured values ​​of the operating parameters of the distillation tower.

[0101] Specifically, at regular intervals, the terminal device monitors the purity of the distillate, the tower bottom liquid level, the tower bottom temperature, the stripping section temperature, the rectifying section temperature, and the flow rate of the tower top outlet. Preferably, the sampling period of each control variable is 0.5 min, and 4 samples are taken in each round, and the average value is taken as the sampling result and input into the terminal device.

[0102] By comparing the current measured value of the distillation tower operating parameter with the target range of the distillation tower operating parameter, the current working state of the distillation tower can be determined. Then, according to the current working state of the distillation tower, one or more parameters with the greatest influence on the current working state can be selected from the distillation tower operating parameters as control variables.

[0103] Step S204: performing a difference judgment between the current measured value of each control variable and the target upper limit value.

[0104] Step S205A: If the judgment result is that there is a difference, the controlled variable is controlled and adjusted.

[0105] Specifically, if it is determined that there is a difference, the controlled variable is controlled and adjusted accordingly, so that the value of the controlled variable is adjusted to the target upper limit value. The control logic of the controlled variable is implemented by the PID algorithm.

[0106] It should be noted that the controlled variables can be divided into primary controlled variables and secondary controlled variables. Generally speaking, if the difference between the current measured value of the controlled variable and the target upper limit value is small, the control adjustment can be performed only through the primary controlled variable; if the difference between the current measured value of the controlled variable and the target upper limit value is large, or the value of the controlled variable is difficult to adjust, the primary controlled variable and the secondary controlled variable can be used for coordinated control and adjustment.

[0107] Step S205B: If the judgment result is that there is no difference, it is considered that the control variable has reached a stable state in the current sampling period and directly enters the next sampling period.

[0108] Step S206: Repeat the above steps to keep each operating parameter stable at the target upper limit value.

[0109] The process flow of high-purity acrylonitrile distillation can be divided into three working states. According to different working states, the distillation tower control method of this embodiment sets different control processes to adapt to the working rules of the distillation tower itself. Figure 4 As shown, the different control processes set in different working conditions of the distillation tower are as follows:

[0110] ①Feeding stage

[0111] When the current measured value of the tower bottom liquid level is less than the target lower limit value of the tower bottom liquid level, the current working state of the distillation tower is the feeding stage. At this time, the control variables of the feeding stage can be determined as the tower bottom liquid level and the tower bottom temperature.

[0112] The main controlled variable corresponding to the bottom liquid level in the feeding stage can be set as the inlet valve opening.

[0113] The main controlled variable corresponding to the tower kettle temperature in the charging stage can be set to the steam valve opening. In addition, the tower kettle temperature in the charging stage also needs to use secondary controlled variables for auxiliary control. The secondary controlled variables corresponding to the tower kettle temperature in the charging stage can be set to the inlet valve opening and the preheater temperature (that is, the set temperature of the preheater).

[0114] In the feeding stage, the target lower limit of the tower bottom liquid level can be set to 50%, and the target upper limit of the tower bottom liquid level can be set to 80%; the target lower limit of the tower bottom temperature can be set to 70°C, and the target upper limit of the tower bottom temperature can be set to 78°C. The target upper limit of the preheater set temperature can be set to 35°C. The relative coefficient of the auxiliary control of the preheater set temperature in this stage is 0.4, and the relative coefficient of the auxiliary control of the inlet valve opening of the distillation tower is 0.6.

[0115] ② Heating stage

[0116] When the current measured value of the tower bottom liquid level is greater than the target upper limit value of the tower bottom liquid level, the current working state of the distillation tower is the heating stage. At this time, the control variables of the heating stage can be determined as the tower bottom liquid level, the tower bottom temperature, the stripping section temperature and the distillation section temperature.

[0117] The main controlled variable corresponding to the tower bottom liquid level in the heating stage can be set to the inlet valve opening. In addition, the tower bottom liquid level in the heating stage also needs to use a secondary controlled variable for auxiliary control, and the secondary controlled variable corresponding to the tower bottom liquid level in the heating stage can be set to the outlet valve opening.

[0118] The tower bottom temperature in the heating stage can be auxiliary controlled only by the secondary controlled variable. Therefore, the secondary controlled variable corresponding to the tower bottom temperature in the heating stage can be set to the preheater temperature and the inlet valve opening.

[0119] The main controlled variables corresponding to the temperature of the stripping section during the heating stage can be set to the power of the stripping section insulation jacket and the opening of the steam valve.

[0120] The main controlled variables corresponding to the temperature of the distillation section during the temperature rise phase can be set to the power of the distillation section insulation jacket and the opening of the steam valve.

[0121] In the heating stage, the target lower limit of the tower kettle liquid level can be set to 50%, and the target upper limit of the tower kettle liquid level can be set to 75%; the target lower limit of the tower kettle temperature can be set to 75°C, and the target upper limit of the tower kettle temperature can be set to 79°C; the target upper limit of the preheater set temperature can be set to 40°C; and the target upper limit of the insulation jacket power can be set to 8kW. In this stage, the relative coefficient of the auxiliary control tower kettle outlet valve opening is set to 0.5, the relative coefficient of the auxiliary control preheater set temperature is set to 0.4, and the relative coefficient of the auxiliary control distillation tower inlet valve opening is set to 0.7.

[0122] ③ Extraction stage

[0123] When the current measured value of the tower top extraction flow rate is greater than the target upper limit value of the tower top extraction flow rate, the current working state of the distillation tower is the extraction stage. At this time, the control variables of the extraction stage can be determined as the tower bottom liquid level, tower bottom temperature, stripping section temperature, distillation section temperature, tower top product composition and tower top extraction flow rate.

[0124] The main controlled variable corresponding to the tower bottom liquid level in the extraction stage can be set to the inlet valve opening. In addition, the tower bottom liquid level in the extraction stage also needs to use a secondary controlled variable for auxiliary control, and the secondary controlled variable corresponding to the tower bottom liquid level in the extraction stage can be set to the outlet valve opening.

[0125] The tower bottom temperature in the extraction stage can be auxiliary controlled only by the secondary controlled variables. Therefore, the secondary controlled variables corresponding to the tower bottom temperature in the extraction stage can be set to the preheater temperature and the inlet valve opening.

[0126] The main controlled variables corresponding to the stripping section temperature in the production phase can be set to the stripping section insulation jacket power and the steam valve opening.

[0127] The main controlled variables corresponding to the temperature of the distillation section in the extraction stage can be set to the power of the distillation section insulation jacket and the opening of the steam valve.

[0128] The main controlled variable corresponding to the composition of the top product in the extraction stage can be set as the reflux ratio of the distillation tower.

[0129] The main controlled variable corresponding to the top tower production flow rate in the production stage can be set to the steam valve opening.

[0130] In the extraction stage, the target lower limit of the tower bottom liquid level can be set to 45%, and the target upper limit of the tower bottom liquid level can be set to 70%; the target lower limit of the tower bottom temperature can be set to 76°C, and the target upper limit of the tower bottom temperature can be set to 80°C; the target upper limit of the distillate purity can be set to 99.99%; the target lower limit of the tower top extraction flow rate can be set to 50mL / min, and the target upper limit of the tower top extraction flow rate can be set to 200mL / min. In this stage, the relative coefficient of the auxiliary control outlet valve opening is set to 0.6, the relative coefficient of the auxiliary control preheater set temperature is set to 0.4, and the relative coefficient of the auxiliary control distillation tower inlet valve opening is set to 0.6.

[0131] In the above control process, within a sampling period, the PID algorithm of the control logic of the inlet valve, outlet valve, and steam valve of the distillation tower is as follows:

[0132] v(x)=v(x-1)+K p1 [L(x)-L(x-1)]+K i1 L(x)+K d1 [L(x)-2L(x-1)+L(x-2)].

[0133] Where v(x) is the target adjustment value of the valve opening, v(x-1) is the current measured value of the valve opening, L(x) is the difference between the current measured value of the control variable and the target upper limit value in the current sampling period, L(x-1) is the difference between the current measured value of the control variable and the target upper limit value in the previous sampling period, L(x-2) is the difference between the current measured value of the control variable and the target upper limit value in the previous two sampling periods, and K p1 is the proportional coefficient of valve opening, K i1 is the integral coefficient of valve opening, K d1 is the differential coefficient of valve opening.

[0134] In one sampling period, the PID algorithm of the control logic of the preheater temperature is as follows:

[0135] T(x)=T(x-1)+K p2 [L(x)-L(x-1)]+K i2 L(x)+K d2 [L(x)-2L(x-1)+L(x-2)].

[0136] Where, T(x) is the target adjustment value of the preheater temperature, T(x-1) is the current measured value of the preheater temperature, L(x) is the difference between the current measured value of the control variable and the target upper limit value in the current sampling period, L(x-1) is the difference between the current measured value of the control variable and the target upper limit value in the previous sampling period, L(x-2) is the difference between the current measured value of the control variable and the target upper limit value in the previous two sampling periods, and K p2 is the proportionality coefficient of the preheater temperature, K i2 is the integral coefficient of the preheater temperature, K d2 is the differential coefficient of the preheater temperature. It should be noted that T(x) cannot be greater than the upper limit of the preheater temperature setting.

[0137] In one sampling period, the PID algorithm of the control logic of the insulation jacket power is as follows:

[0138] P(x)=P(x-1)+K p3 [L(x)-L(x-1)]+K i3 L(x)+K d3 [L(x)-2L(x-1)+L(x-2)].

[0139] Where P(x) is the target adjustment value of the insulation sleeve power, P(x-1) is the current measured value of the insulation sleeve power, L(x) is the difference between the current measured value of the control variable and the target upper limit value in the current sampling period, L(x-1) is the difference between the current measured value of the control variable and the target upper limit value in the previous sampling period, L(x-2) is the difference between the current measured value of the control variable and the target upper limit value in the previous two sampling periods, and K p3 K is the proportional coefficient of the insulation jacket power, i3 K is the integral coefficient of the insulation jacket power, d3 is the differential coefficient of the insulation sleeve power. It should be noted that P(x) cannot be greater than the upper limit of the insulation sleeve power setting.

[0140] In one sampling period, the PID algorithm of the reflux ratio control logic is as follows:

[0141] R(x)=R(x-1)+K p4 [L(x)-L(x-1)]+K i4 L(x)+K d4[L(x)-2L(x-1)+L(x-2)].

[0142] Wherein, R(x) is the difference between the current value of the reflux ratio and the target value of the reflux ratio, R(x-1) is the difference between the current value of the reflux ratio and the target value of the reflux ratio in the previous sampling period, L(x) is the difference between the purity of the current product and the purity of the target product in the current sampling period, L(x-1) is the difference between the purity of the current product and the purity of the target product in the previous sampling period, L(x-2) is the difference between the purity of the current product and the purity of the target product in the previous two sampling periods, and K p4 is the proportionality coefficient of the reflux ratio, K i4 is the integral coefficient of the reflux ratio, K d4 is the differential coefficient of the reflux ratio.

[0143] It should be noted that the PID algorithm of the control logic of the inlet valve, outlet valve, steam valve, preheater temperature and insulation jacket power in this process, when the current measured value of the control variable is less than the target lower limit value, the proportional coefficient K of the control of the inlet valve opening is set to p1 , K p2 and K p3 Set to the set initial value; when the current measured value of the control variable is greater than the target lower limit and less than the target upper limit, the proportional coefficient K of the control of the inlet valve opening is set to p1 , K p2 and K p3 Set to set the initial value multiplied by a limiting factor; when the current measured value of the control variable is greater than the target upper limit, the proportional coefficient K of the control of the inlet valve opening is set to p1 , K p2 and K p3 Reset to the initial value.

[0144] The limiting factor is calculated as follows:

[0145]

[0146] Among them, θ is the limiting factor, L0 is the current measured value of the control variable, L1 is the target lower limit value of the control variable, L2 is the target upper limit value of the control variable, k is a custom constant, and the value of k in this process is 0.5.

[0147] Embodiment 3

[0148] The third embodiment of the present invention further provides a terminal device, see Figure 5 The terminal device includes a processor 1901 and a memory 1902, in which at least one computer program is stored. The at least one computer program is loaded and executed by one or more of the above processors so that the terminal device implements the distillation tower control method as described above.

[0149] Of course, the terminal device may also have components such as a wired or wireless network interface, a keyboard, and an input / output interface for input and output. The terminal device may also include other components for realizing various functions of the device, which will not be described in detail here.

[0150] The third embodiment of the present invention further provides a computer-readable storage medium, in which at least one program code is stored. The program code is loaded and executed by a processor to enable a computer to implement the distillation tower control method as described above.

[0151] Alternatively, the computer-readable storage medium may be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The storage medium may be any available medium that can be accessed by a general or special purpose computer.

[0152] Those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions to enable a single-chip microcomputer, a chip or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0153] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0154] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0155] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A distillation tower control method, characterized in that: The control method comprises: During the current sampling period, obtain the current measured values ​​of the distillation tower operating parameters; Based on the comparison result of the current measured value of the distillation tower working parameter and the target range, the current working state of the distillation tower is judged; Determine the controlled variables and controlled variables under the current working state; When it is determined that there is a difference between the current measured value of the control variable and the target range of the control variable, determining a target adjustment value of the controlled variable based on a PID algorithm, and adjusting the controlled variable of the distillation column according to the target adjustment value of the controlled variable; When it is determined that there is no difference between the current measured value of the control variable and the target range, directly enter the next sampling cycle; Wherein, the operating parameters of the distillation tower include the bottom liquid level, the bottom temperature, the stripping section temperature, the distillation section temperature, the top product composition and the top extraction flow rate; the controlled variable is at least one of the operating parameters of the distillation tower; the controlled variables include main controlled variables, and the main controlled variables are at least one of the opening of the bottom steam valve, the opening of the inlet valve of the distillation tower, the power of the stripping section insulation jacket, the power of the distillation section insulation jacket and the reflux ratio of the distillation tower; the target range includes a target upper limit value and a target lower limit value.

2. The distillation tower control method according to claim 1, characterized in that: The controlled variable also includes: a secondary controlled variable, which is at least one of the set temperature of the preheater, the opening of the inlet valve of the distillation tower, and the opening of the outlet valve of the tower bottom.

3. The distillation tower control method according to claim 1 or 2, characterized in that: The current working state of the distillation tower is judged based on the comparison result between the current measured value of the working parameter of the distillation tower and the target range, including: When it is determined that the current measured value of the tower bottom liquid level is less than the target lower limit value of the tower bottom liquid level, determining that the current working state is the feeding stage; When it is determined that the current measured value of the tower bottom liquid level is greater than the target lower limit value of the tower bottom liquid level, the current working state is determined to be a heating stage; When it is determined that the current measured value of the tower top production flow rate is greater than the target lower limit value of the tower top production flow rate, it is determined that the current working state is the production stage.

4. The distillation tower control method according to claim 3, characterized in that: Determining the control variable and the controlled variable in the current working state includes: The control variable in the feeding stage is determined as the tower bottom temperature, and the main controlled variable corresponding to the tower bottom temperature in the feeding stage is determined as the opening of the tower bottom steam valve.

5. The distillation tower control method according to claim 4, characterized in that: The secondary controlled variables corresponding to the tower bottom temperature in the feeding stage are determined as the set temperature of the preheater and the opening of the inlet valve of the distillation tower.

6. The distillation tower control method according to claim 3, characterized in that: The determining of the control variable and the controlled variable in the current working state also includes: The control variables in the temperature rising stage are determined as the tower bottom liquid level, tower bottom temperature, stripping section temperature and rectifying section temperature; The main controlled variable corresponding to the tower bottom liquid level in the temperature rising stage is determined as the opening of the inlet valve of the distillation tower; The main controlled variables corresponding to the temperature of the stripping section in the heating stage are determined as the opening of the bottom steam valve and the power of the stripping section insulation jacket; The main controlled variables corresponding to the temperature of the distillation section during the heating stage are determined as the opening of the bottom steam valve and the power of the insulation jacket of the distillation section.

7. The distillation tower control method according to claim 6, characterized in that: The secondary controlled variable corresponding to the tower bottom liquid level in the heating stage is determined as the tower bottom outlet valve opening; and the secondary controlled variable corresponding to the tower bottom temperature in the heating stage is determined as the set temperature of the preheater and the inlet valve opening of the distillation tower.

8. The distillation tower control method according to claim 3, characterized in that: The determining of the control variable and the controlled variable in the current working state also includes: The control variables of the extraction stage are determined as the tower bottom liquid level, tower bottom temperature, stripping section temperature, rectifying section temperature, tower top product composition and tower top extraction flow rate; The main controlled variable corresponding to the tower bottom liquid level in the extraction stage is determined as the opening of the inlet valve of the distillation tower; The main controlled variable corresponding to the temperature of the stripping section in the production phase is determined as the power of the stripping section insulation jacket; The main controlled variable corresponding to the temperature of the distillation section in the extraction stage is determined as the power of the insulation jacket of the distillation section; The main controlled variable corresponding to the composition of the tower top product in the extraction stage is determined as the reflux ratio of the distillation tower; The main controlled variable corresponding to the tower top production flow rate in the production stage is determined as the tower bottom steam valve opening.

9. The distillation tower control method according to claim 8, characterized in that: The secondary controlled variable corresponding to the tower bottom liquid level in the extraction stage is determined as the tower bottom outlet valve opening; and the secondary controlled variable corresponding to the tower bottom temperature in the extraction stage is determined as the set temperature of the preheater and the inlet valve opening of the distillation tower.

10. The distillation tower control method according to claim 1 or 2, characterized in that: The calculation formula of the PID algorithm is: f(x) = f(x-1)+K p [L(x)-L(x-1)]+K i L(x)+K d [L(x)-2L(x-1)+L(x-2)]; Where f(x) is the target adjustment value of the controlled variable, L(x) is the difference between the current measured value of the controlled variable and the target range in the current sampling period, L(x-1) is the difference between the current measured value of the controlled variable and the target range in the previous sampling period, L(x-2) is the difference between the current measured value of the controlled variable and the target range in the previous two sampling periods, and K p is the proportionality coefficient, K i is the integration coefficient, K d is the differential coefficient.

11. The distillation tower control method according to claim 10, characterized in that: When the current measured value of the control variable is less than the target lower limit value of the control variable, or when the current measured value of the control variable is greater than the target upper limit value of the control variable, the proportional coefficient of the main controlled variable is determined as the set initial value; When the current measured value of the control variable is greater than the target lower limit value of the control variable and less than the target upper limit value of the control variable, the proportional coefficient of the main controlled variable is determined as the product of the set initial value and the limiting factor; The calculation formula of the limiting factor is: Where θ is the limiting factor, L0 is the current measured value of the control variable, L1 is the target lower limit of the control variable, L2 is the target upper limit of the control variable, k is a custom constant, and 0.2 <k<1。 12. The distillation tower control method according to claim 10, characterized in that: The proportional coefficient of the secondary controlled variable is determined as the product of the set initial value and the relative coefficient, and the value of the relative coefficient is 0.2 to 0.

9.

13. A terminal device, characterized in that: The terminal device includes a processor and a memory, wherein at least one computer program is stored in the memory, and the at least one computer program is loaded and executed by one or more of the above processors, so that the terminal device implements the distillation tower control method described in any one of claims 1 to 12.

14. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one program code, and the program code is loaded and executed by a processor so that a computer implements the distillation tower control method according to any one of claims 1 to 12.

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