Rectification column control method, terminal device, and readable storage medium

Abstract

The present application provides a kind of rectifying column control method, terminal equipment and readable storage medium, belong to chemical separation technical field, the control method includes: based on the comparison result of current measurement value and target range of rectifying column operating parameter, determine the control variable and controlled variable under current operating state;In the case where there is difference between the current measurement value of the determined control variable and the target range of control variable, determine the target adjustment value of controlled variable based on PID algorithm;According to the target adjustment value of controlled variable, adjust rectifying column.Wherein, control variable is at least one of rectifying column operating parameter, and controlled variable is at least one of tower bottom vapor valve opening, rectifying column import valve opening, distillation section heat preservation cover power, rectifying section heat preservation cover power and rectifying column reflux ratio.The method provided by the present application can achieve accurate rectifying column adjustment effect, significantly optimize the control process of rectifying column, improve work efficiency and reduce operating cost.

Description

Technical Field

[0001] This invention relates to the field of chemical separation technology, specifically to a distillation column control method, a terminal device, and a computer-readable storage medium. Background Technology

[0002] Chemical separation processes are a core component of chemical engineering, and distillation columns are widely used in these processes. Their principle is based on the difference in relative volatility between different substances to separate the components. The operating conditions of the distillation column are crucial for successful separation. Many operating parameters, such as temperature, pressure, and flow rate, are involved in the operation of a distillation column. To ensure smooth operation, these parameters need to be monitored, and appropriate equipment needs to be adjusted to achieve ideal values. Typically, the monitoring and adjustment of distillation column operating parameters are done manually.

[0003] However, with the development of the chemical industry, the requirements for distillation technology and product quality are becoming increasingly stringent. The current manual monitoring and adjustment methods are becoming less and less suitable for the new stage of chemical industry development. Manual adjustment inevitably suffers from drawbacks such as adjustment lag, reliance on staff experience, and a lack of standardized procedures. These drawbacks negatively impact the overall energy consumption, control optimization, and product purity of the distillation column.

[0004] To address the adverse effects of manually adjusting the operating parameters of distillation columns, researchers have proposed using automated programs to monitor, adjust, and provide feedback on these parameters, thereby achieving automated control of the distillation column. Automated control of the distillation column not only optimizes control performance and reduces parameter delays, but also improves product purity, reduces the production of substandard products, and achieves overall automated control of the entire column. Furthermore, automated control enables the interconnected control of multiple variables within the distillation column, which is difficult to achieve manually. By setting priority control weights for different variables and determining primary and auxiliary control variables, precise control of the distillation column can be achieved.

[0005] However, current automated control methods for distillation columns can only control a limited number of parameters, resulting in limited overall control over the column. For example, Chinese patent document CN115400444A, published on November 29, 2022, proposes a distillation column control method. This method includes: real-time acquisition of the current reboiler level and temperature; and controlling the column's operating status based on the current reboiler level, temperature, and preset target column information. This invention can effectively control the reboiler temperature and level, achieving automated control of the distillation column. However, this method controls only a single variable, resulting in low accuracy. Furthermore, the limited number of controlled variables, focusing only on the reboiler level and temperature, limits the overall control over the distillation column. Summary of the Invention

[0006] To address the technical problem that existing automated control methods for distillation columns have very limited control over the entire distillation column, this invention provides a distillation column control method. This method allows for the setting of different control processes for different operating states of the distillation column, effectively adapting to the working patterns of the distillation column itself.

[0007] To achieve the above objectives, the first aspect of the present invention provides a distillation column control method, the control method comprising the following steps: acquiring the current measured values ​​of the operating parameters of the distillation column within the current sampling period; determining the current operating state based on a comparison between the current measured values ​​of the operating parameters of the distillation column and a target range; determining the control variable and the controlled variable under the current operating state of the distillation column; determining the target adjustment value of the controlled variable based on a PID algorithm when a difference exists between the current measured value of the control variable and the target range; adjusting the controlled variable of the distillation column according to the target adjustment value of the controlled variable; and adjusting the... The distillation column, upon determining that there is no difference between the current measured value of the control variable and the target range of the control variable, directly enters the next sampling cycle; wherein, the operating parameters of the distillation column include: column bottom liquid level, column bottom temperature, stripping section temperature, rectifying section temperature, column top product composition, and column top outflow rate; the control variable is at least one of the operating parameters of the distillation column; the controlled variable includes the main controlled variable, which is at least one of the following: column bottom steam valve opening, distillation column inlet valve opening, stripping section insulation jacket power, rectifying section insulation jacket power, and distillation column reflux ratio; 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, wherein the secondary controlled variable is at least one of the preheater set temperature, the inlet valve opening of the distillation column, and the outlet valve opening of the column bottom.

[0009] In an exemplary embodiment of the present invention, determining the current operating state of the distillation column based on the comparison between the current measured value and the target range of the distillation column's operating parameters may include: determining the current operating state as a feeding stage when the current measured value of the bottom liquid level is less than the target lower limit of the bottom liquid level; determining the current operating state as a heating stage when the current measured value of the bottom liquid level is greater than the target lower limit of the bottom liquid level; and determining the current operating state as a dispensing stage when the current measured value of the top dispensing flow rate is greater than the target lower limit of the top dispensing flow rate.

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

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

[0012] In an exemplary embodiment of the present invention, determining the control variables and controlled variables under the current operating state may further include: determining the control variables for the heating stage as the reboiler level, reboiler temperature, stripping section temperature, and rectifying section temperature; determining the main controlled variable corresponding to the reboiler level during the heating stage as the inlet valve opening of the rectifying column; determining the main controlled variables corresponding to the stripping section temperature during the heating stage as the bottom steam valve opening and the power of the stripping section insulation jacket; and determining the main controlled variables corresponding to the rectifying section temperature during the heating stage as the bottom steam valve opening 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 during the heating stage can be determined as the bottom outlet valve opening; and the secondary controlled variable corresponding to the bottom temperature during the heating stage can be determined as the preheater set temperature and the distillation column inlet valve opening.

[0014] In an exemplary embodiment of the present invention, determining the control variables and controlled variables under the current operating state may further include: determining the control variables for 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 rectifying column; 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 rectifying column; and determining the main controlled variable corresponding to the top extraction flow rate in the extraction stage as the bottom steam valve opening.

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

[0016] In an exemplary embodiment of the present invention, the calculation formula of the PID algorithm can 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 K is the proportionality coefficient. i K is the integral coefficient. d is the differential coefficient.

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

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

[0021] The formula for calculating the limiting factor is:

[0022]

[0023] Where θ is the constraint 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, and k is a user-defined constant, 0.2. <k<1。

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

[0025] A second aspect of the present invention provides a terminal device, the terminal device including a processor and a memory, the memory storing at least one computer program, the at least one computer program being loaded and executed by one or more of the processors to enable the terminal device to implement the distillation column control method described above.

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

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

[0028] (1) The distillation column control method of the present invention sets different control variables and controlled variables for adjusting the control variables for different working states. By adjusting the controlled variables to the target value, the working parameters of the distillation column (such as column bottom temperature, column bottom liquid level, etc.) are precisely controlled. This not only realizes the automated control of the distillation column, but also improves work efficiency and avoids safety accidents caused by human operation errors.

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

[0030] (3) The distillation column control method of the present invention sets up a multivariate control process with different priorities for different working states, which can realize the mutual linkage control between multiple variables of the distillation column, making the whole control process more accurate and efficient.

[0031] (4) By establishing a mediation network of different levels between each control variable and the controlled variable, this invention can significantly optimize the control process of the distillation column, improve work efficiency, and reduce operating costs.

[0032] (5) The present invention can acquire the working parameters of the distillation column in real time, and use a computer program to adjust the various parameters in the distillation column in real time according to the preset target value, so as to realize the automatic control of the entire distillation column, which can effectively improve the working efficiency of the distillation column and optimize energy consumption and product quality.

[0033] (6) The control method for the distillation column adopted in this invention has low requirements for the distillation column 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 section. Attached Figure Description

[0035] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0036] Figure 1 This is a schematic flowchart of the distillation column control method provided in the first embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of the distillation column and terminal equipment provided in the second embodiment of the present invention;

[0038] Figure 3 A schematic flowchart of the distillation column control method provided in the second embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of the distillation column control logic under different operating states provided in the second embodiment of the present invention;

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

[0041] Explanation of reference numerals in the attached figures

[0042] 1-Raw material tank, 2-Raw material preheater, 3-Distillation column, 4-Condenser, 5-Reboiler, 6-Reflux ratio controller, 7-Rectifying section insulation jacket, 8-Stripping section insulation jacket, 9-Gas chromatograph, 10-Column bottom level gauge, 11-Column bottom thermometer, 12-Stripping section thermometer, 13-Rectifying section thermometer, 14-Column top thermometer, 15-Column top outlet flow meter, 16-Inlet valve, 17-Column bottom outlet valve, 18-Steam valve, 19-Terminal equipment, 1901-Processor, 1902-Memory. Detailed Implementation

[0043] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0044] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0045] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used to describe the relative positional relationships of components in relation to the directions shown in the accompanying drawings or in relation to vertical, perpendicular, or gravitational directions. Terms such as "first" and "second" are used merely for ease of description and distinction and should not be construed as indicating or implying relative importance.

[0046] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integrated connection; they can refer to a direct connection or an indirect connection; they can refer to a wired connection or a wireless connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

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

[0048] Example 1

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

[0050] Step S101: Within the current sampling period, obtain the current measured values ​​of the operating parameters of the distillation column.

[0051] It should be noted that distillation is a process that separates components in a mixture by utilizing their different volatility. A typical distillation unit is a continuous distillation apparatus, consisting of a distillation column, a reboiler, and a condenser. The distillation column provides contact between the vapor and liquid phases for interphase mass transfer. The condenser at the top of the column partially condenses the vapor, with some of the condensate returning to the top as reflux, and the remaining distillate being the top product.

[0052] The internal structure of a distillation column can be divided into three main parts: the top section, the body section, and the reboiler section. A distillation column generally has a feed inlet, a top outlet, and a reboiler outlet. The feed inlet is located in the middle of the body and is connected to a preheater for preheating the feed liquid. The body section consists of a rectifying section and a stripping section. The rectifying section extends from the feed tray above the feed inlet to the top of the column, while the stripping section extends from the feed tray below the feed inlet to the reboiler. After being preheated to a certain temperature and pressure, the feed liquid enters the distillation column. The more volatile light components are gradually concentrated in the rectifying section, forming the top product (distillate); while the less volatile heavy components are gradually concentrated in the stripping section, forming the reboiler product (residue). The reboiler section is equipped with a reboiler to reheat the liquid descending from the column. The top section of the column is equipped with a condenser and a reflux ratio controller. The condenser cools the top distillate from vapor to liquid, and the reflux ratio controller adjusts the reflux ratio. The reflux ratio is the ratio of the amount of liquid flowing back into the column from the top to the amount of product. It is an important control parameter in distillation operations, and its changes affect the separation efficiency and energy consumption.

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

[0054] Step S102: Based on the comparison between the current measured values ​​of the distillation column's operating parameters and the target range, determine the current operating status of the distillation column.

[0055] Generally speaking, a target range should be set in advance for the operating parameters of each distillation column. When the values ​​of the operating parameters are within the preset target range, a better separation effect can be achieved. Different operating parameters of a distillation column can reflect its operating status. Therefore, by comparing the current measured values ​​of the operating parameters with the target range, the current operating status of the distillation column can be determined.

[0056] For example, the current operating status of a distillation column can be determined by comparing the current measured values ​​of the bottom liquid level and the top flow rate with the target range. A target upper limit and a target lower limit can be preset for both the bottom liquid level and the top flow rate, and the interval formed by these two limits is defined as the target range for the corresponding operating parameters.

[0057] When the current measured value of the bottom liquid level is less than the target lower limit of the bottom liquid level, the current operating state of the distillation column can be determined to be 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, the current operating state of the distillation column can be determined to be the heating stage; when the current measured value of the top outflow rate is greater than the target lower limit of the top outflow rate, the current operating state of the distillation column can be determined to be the outflow stage.

[0058] Step S103: Determine the control variables and controlled variables under the current working state.

[0059] Here, a control variable refers to one or more operating parameters that can affect the operating performance of the distillation column under the current operating conditions. In other words, a control variable is one or more parameters selected from multiple distillation column operating parameters based on the current operating conditions, which can be used to adjust the operating performance of the distillation column.

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

[0061] It should be noted that distillation column control parameters refer to the parameters monitored by the distillation column control equipment, which in turn refers to the equipment connected to the various inlets and outlets of the distillation column and capable of monitoring the physical properties of the materials entering and exiting the column. For example, distillation column control equipment can be thermometers installed at the top of the column, the rectifying section, the stripping section, and the reboiler; it can also be flow meters and product detectors installed at the top outlet; or valves installed at the inlet, the top outlet, and the reboiler outlet.

[0062] Step S104A: If there is a difference between the current measured value of the control variable and the target range of the control variable, determine the target adjustment value of the controlled variable based on the 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 of the control variable; or it can refer to the difference between the current measured value of the control variable and the target lower limit of the control variable.

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

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

[0066] The above technical solution involves collecting the operating parameters of the distillation column at regular intervals and determining the control variables under different operating conditions. Then, the difference between the current measured value of the control variable and the target range (e.g., the target upper limit) is judged. If a difference is found, the controlled variable is adjusted and controlled through the control logic, which is implemented by a PID algorithm. If no difference is found, the next sampling cycle is directly entered. The above control process is repeated to maintain the stability of the control variable within the target range.

[0067] In this embodiment, the controlled variable may include a main controlled variable, which is at least one of the following: the opening degree of the bottom steam valve, the opening degree of the inlet valve of the distillation column, the power of the stripping section insulation jacket, the power of the rectification section insulation jacket, and the reflux ratio of the distillation column.

[0068] Furthermore, in one possible implementation, the controlled variable may also include a secondary controlled variable, which is at least one of the following: the set temperature of the preheater, the opening degree of the inlet valve of the distillation column, and the opening degree of the outlet valve of the column reboiler. That is, when there is a controlled variable that is an auxiliary control, the auxiliary controlled variable is treated as a secondary controlled variable and is adjusted together with the primary controlled variable.

[0069] Furthermore, in one possible implementation, when the current operating state of the distillation column is determined to be the feeding stage, the control variable for the feeding stage can be determined as the column bottom temperature, and the main controlled variable corresponding to the column bottom temperature in the feeding stage can be determined as the opening degree of the bottom steam valve.

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

[0071] Furthermore, in one possible implementation, when it is determined that the current operating state of the distillation column is in the heating stage, the control variables for the heating stage can be determined as the bottom liquid level, bottom temperature, stripping section temperature, and rectification section temperature.

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

[0073] Additionally, the secondary controlled variable corresponding to the bottom liquid level during the heating stage can be determined as the opening degree of the bottom outlet valve. The secondary controlled variable corresponding to the bottom temperature during the heating stage can be determined as the set temperature of the preheater and the opening degree of the inlet valve of the distillation column.

[0074] Furthermore, in one possible implementation, when the current operating state of the distillation column is determined to be the extraction stage, the control variables for the extraction stage can be determined as the bottom liquid level, bottom temperature, stripping section temperature, rectifying section temperature, top product composition, and top extraction flow rate.

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

[0076] Additionally, the secondary controlled variable corresponding to the bottom liquid level during the extraction stage can be determined as the bottom outlet valve opening. Furthermore, the secondary controlled variables corresponding to the bottom temperature during the extraction stage can be determined as the preheater set temperature and the distillation column inlet valve opening.

[0077] Furthermore, the calculation formula for the PID algorithm can be shown in Equation (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 equation (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 K is the proportionality coefficient. i K is the integral coefficient. d is the differential coefficient.

[0080] It should be noted that the proportionality coefficient K in equation (1) above p Adjustments can be made accordingly 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 control variable is less than the target lower limit of the control variable, the proportional coefficient of the main controlled variable is determined as the initial value.

[0082] 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 initial value.

[0083] When the current measured value of the control variable is greater than the target lower limit but less than the target upper limit, the proportional coefficient of the main controlled variable is determined as the product of the initial value and the constraint factor. The constraint factor is calculated as shown in equation (2) below.

[0084]

[0085] In equation (2), 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, and k is a user-defined constant, 0.2. <k<1。

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

[0087] Furthermore, in one possible implementation, the sampling period for the operating parameters of the distillation column can be 0.25 to 1 minute, with 3 to 6 samples taken each time, and the average value is used as the sampling result and input into the computer.

[0088] It should be noted that, Figure 1 This is a schematic flowchart of the distillation column control method provided in this embodiment. It should be understood that, although... Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed; they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed 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 some of the sub-steps or stages of other steps.

[0089] Furthermore, the implementation environment of this embodiment includes at least one terminal and one server, with the method executed on either the terminal or the server. The terminal and server can establish a communication connection to achieve interactive information transmission. For example, the distillation column control method of this embodiment can be applied to a server. The real-time measurement data of the distillation column's operating parameters is stored in the terminal, and the server can receive the real-time measurement data of the distillation column's operating parameters sent by the terminal.

[0090] 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] A server can be a single server, a server cluster consisting of multiple servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, CDN (Content Delivery Network), and big data and artificial intelligence platforms.

[0092] Example 2

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

[0094] Figure 2 This is a schematic diagram showing the connection between an atmospheric distillation unit and a terminal unit for removing trace impurities from raw materials to produce high-purity acrylonitrile. The terminal unit stores a control program for implementing the distillation column control method. Figure 2 As shown, the distillation equipment includes a feed tank 1, a feed preheater 2, a distillation column 3, a condenser 4, a reboiler 5, a reflux ratio controller 6, a rectification section insulation jacket 7, a stripping section insulation jacket 8, a gas chromatograph 9, a column bottom level gauge 10, a column bottom thermometer 11, a stripping section thermometer 12, a rectification section thermometer 13, a column top thermometer 14, a column top outlet flow meter 15, a feed inlet valve 16, a column bottom outlet valve 17, and a steam valve 18. The gas chromatograph 9, column bottom level gauge 10, column bottom thermometer 11, stripping section thermometer 12, rectification section thermometer 13, column top thermometer 14, and column top outlet flow meter 15 can transmit the monitored data to a terminal device 19. The terminal device 19 automatically controls the reflux ratio controller 6, the feed inlet valve 16, the column bottom outlet valve 17, and the steam valve 18 based on the signals and control program.

[0095] The process flow of high-purity acrylonitrile distillation is as follows: Acrylonitrile feedstock is preheated from the feed tank through the feed preheater and then enters the column body from the middle. It is heated by steam in the column bottom and begins to vaporize after reaching a certain temperature. The vaporized product then enters the top of the column for condensation. When the distillation rate at the top of the column reaches the target value, the purity of the distillate at the top of the column is analyzed by gas chromatography. After adjusting the reflux ratio to obtain the product that meets the requirements, it is collected.

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

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

[0098] Step S202: Set the target range of the operating parameters of the distillation column.

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

[0100] Step S203: Monitor the operating parameters of the distillation column according to the sampling period, and determine the control variables under the current operating state based on the current measured values ​​of the operating parameters of the distillation column.

[0101] Specifically, at regular intervals, the terminal equipment monitors the distillate purity, column bottom level, column bottom temperature, stripping section temperature, rectifying section temperature, and column top outlet flow rate. Preferably, the sampling period for each control variable is 0.5 minutes, with four samples taken per round, and the average value is used as the sampling result input to the terminal equipment.

[0102] By comparing the current measured values ​​of the distillation column's operating parameters with the target range of those parameters, the current operating state of the distillation column can be determined. Based on this current operating state, one or more parameters that have the greatest impact on the current operating state can be selected as control variables.

[0103] Step S204: Calculate the difference 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, then the controlled variable is controlled and adjusted.

[0105] Specifically, if a difference is detected, the controlled variable is adjusted accordingly to bring its value to the target upper limit. The control logic for the controlled variable is implemented using a PID algorithm.

[0106] It should be noted that 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 is small, control can be achieved solely through the primary controlled variable; if the difference between the current measured value of the controlled variable and the target upper limit is large, or if the value of the controlled variable is difficult to adjust, coordinated control can be achieved through both the primary and secondary controlled variables.

[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 the next sampling period is directly entered.

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

[0109] The process flow for high-purity acrylonitrile distillation can be divided into three operating states. For each operating state, the distillation column control method in this embodiment employs different control procedures to adapt to the operating characteristics of the distillation column itself. For example... Figure 4 As shown, the different control processes set for different operating states of the distillation column are as follows:

[0110] ① Feeding stage

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

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

[0113] The primary controlled variable for the reboiler temperature during the feeding stage can be set as the steam valve opening. In addition, secondary controlled variables are needed for auxiliary control of the reboiler temperature during the feeding stage. These secondary controlled variables can be set as the inlet valve opening and the preheater temperature (i.e., the preheater's set temperature).

[0114] During the feeding stage, the target lower limit for the column bottom liquid level can be set to 50%, and the target upper limit for the column bottom liquid level can be set to 80%; the target lower limit for the column bottom temperature can be set to 70℃, and the target upper limit for the column bottom temperature can be set to 78℃. The target upper limit for the preheater's set temperature can be set to 35℃. The relative coefficient for auxiliary control of the preheater's set temperature during this stage is 0.4, and the relative coefficient for auxiliary control of the distillation column's inlet valve opening is 0.6.

[0115] ② Heating phase

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

[0117] The primary controlled variable for the bottom liquid level during the heating phase can be set as the inlet valve opening. Additionally, a secondary controlled variable is needed for auxiliary control of the bottom liquid level during the heating phase; this secondary controlled variable can be set as the outlet valve opening.

[0118] The temperature of the column bottom during the heating stage can be controlled by secondary controlled variables. Therefore, the secondary controlled variables corresponding to the temperature of the column bottom during the heating stage can be set as 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 as the power of the stripping section insulation jacket and the opening degree of the steam valve.

[0120] The main controlled variables corresponding to the temperature of the rectification section during the heating stage can be set as the power of the insulation jacket of the rectification section and the opening degree of the steam valve.

[0121] During the heating phase, the target lower limit for the column bottom liquid level can be set to 50%, and the target upper limit for the column bottom liquid level can be set to 75%; the target lower limit for the column bottom temperature can be set to 75℃, and the target upper limit for the column bottom temperature can be set to 79℃; the target upper limit for the preheater's set temperature can be set to 40℃; and the target upper limit for the insulation jacket power can be set to 8kW. During this phase, the relative coefficients for the auxiliary control of the column bottom outlet valve opening are set to 0.5, the relative coefficients for the auxiliary control of the preheater's set temperature are set to 0.4, and the relative coefficients for the auxiliary control of the distillation column inlet valve opening are set to 0.7.

[0122] ③ Extraction stage

[0123] When the current measured value of the top product flow rate exceeds the target upper limit of the top product flow rate, the current operating state of the distillation column is the product flow stage. At this time, the control variables for the product flow stage can be determined as the bottom liquid level, bottom temperature, stripping section temperature, rectifying section temperature, top product composition, and top product flow rate.

[0124] The primary controlled variable for the bottom liquid level during the production stage can be set as the inlet valve opening. In addition, a secondary controlled variable is needed for auxiliary control of the bottom liquid level during the production stage; this secondary controlled variable can be set as the outlet valve opening.

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

[0126] The main controlled variables corresponding to the temperature of the stripping section during the extraction stage can be set as the power of the stripping section insulation jacket and the opening degree of the steam valve.

[0127] The main controlled variables corresponding to the temperature of the rectification section during the extraction stage can be set as the power of the insulation jacket of the rectification section and the opening degree 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 column.

[0129] The main controlled variable corresponding to the top production flow rate during the production phase can be set as the steam valve opening.

[0130] During the extraction stage, the target lower limit for the reboiler level can be set to 45%, and the target upper limit to 70%; the target lower limit for the reboiler temperature can be set to 76℃, and the target upper limit to 80℃; the target upper limit for the distillate purity can be set to 99.99%; the target lower limit for the top product flow rate can be set to 50 mL / min, and the target upper limit to 200 mL / min. The relative coefficients for the auxiliary control outlet valve opening, the auxiliary control preheater set temperature, and the auxiliary control distillation column inlet valve opening can all be set to 0.6.

[0131] In the above control flow, the PID algorithm for the control logic of the inlet valve, outlet valve, and steam valve of the distillation column within one sampling period 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 K is the proportional coefficient for valve opening. i1 K is the integral coefficient of the valve opening. d1 This is the differential coefficient of the valve opening.

[0134] The PID algorithm for controlling the preheater temperature within one sampling period 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 setpoint for 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 K is the proportionality coefficient for the preheater temperature. i2 K is the integral coefficient for the preheater temperature. d2 This is the differential coefficient for the preheater temperature. It should be noted that T(x) cannot exceed the upper limit set for the preheater temperature.

[0137] The PID algorithm for controlling the power of the insulation jacket within one sampling period 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 jacket power, P(x-1) is the current measured value of the insulation jacket 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 proportionality coefficient of the insulation jacket power. i3 K is the integral coefficient of the insulation jacket power. d3 This represents the differential coefficient of the insulation jacket's power. It should be noted that P(x) cannot exceed the upper limit set for the insulation jacket's power.

[0140] The PID algorithm for the reflux ratio control logic within one sampling period 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] Where R(x) is the difference between the current reflux ratio and the target reflux ratio, R(x-1) is the difference between the current reflux ratio and the target reflux ratio in the previous sampling period, L(x) is the difference between the current product purity and the target product purity in the current sampling period, L(x-1) is the difference between the current product purity and the target product purity in the previous sampling period, L(x-2) is the difference between the current product purity and the target product purity in the previous two sampling periods, and K... p4 K is the proportionality coefficient for the reflux ratio. i4 K is the integral coefficient of the reflux ratio. d4 is the differential coefficient of the reflux ratio.

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

[0144] The limitation factor is calculated as follows:

[0145]

[0146] Where θ is the constraint 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, and k is a user-defined constant, with a value of 0.5 in this process.

[0147] Example 3

[0148] The third embodiment of the present invention also provides a terminal device, see below. Figure 5 The terminal device includes a processor 1901 and a memory 1902, the memory storing at least one computer program, which is loaded and executed by one or more of the processors to enable the terminal device to implement the distillation column control method as described above.

[0149] Of course, the terminal device may also have wired or wireless network interfaces, keyboards, and input / output interfaces for input and output. The terminal device may also include other components for implementing the various functions of the device, which will not be elaborated here.

[0150] A third embodiment of the present invention also provides a computer-readable storage medium storing at least one piece of program code, which is loaded and executed by a processor to enable a computer to implement the distillation column control method as described above.

[0151] Optionally, the computer-readable storage medium can 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 storage, flash memory, magnetic disk, or optical disk. The storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0152] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0153] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within 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 describe the various possible combinations separately.

[0155] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for controlling a distillation column, characterized in that, The control method includes: Within the current sampling period, obtain the current measured values ​​of the operating parameters of the distillation column; Based on the comparison between the current measured values ​​of the distillation column's operating parameters and the target range, the current operating status of the distillation column is determined. Determine the control variables and controlled variables in the current operating 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, the target adjustment value of the controlled variable is determined based on the PID algorithm, and the controlled variable of the distillation column is adjusted according to the target adjustment value of the controlled variable. If it is determined that there is no difference between the current measured value of the control variable and the target range, proceed directly to the next sampling period; The distillation column operating parameters include the reboiler level, reboiler temperature, stripping section temperature, rectifying section temperature, top product composition, and top outflow rate. The controlled variables are at least one of the distillation column operating parameters. The controlled variables include primary controlled variables, which are at least one of the following: bottom steam valve opening, distillation column inlet valve opening, stripping section insulation jacket power, rectifying section insulation jacket power, and distillation column reflux ratio. The controlled variables also include secondary controlled variables, which are at least one of the following: preheater setpoint temperature, distillation column inlet valve opening, and reboiler outlet valve opening. The target range includes an upper target value and a lower target value. The calculation formula for the PID algorithm is: ； in, f ( x ) represents the target adjustment value of the controlled variable. L ( x The value represents the difference between the current measured value of the control variable and the target range within the current sampling period. L ( x -1) represents the difference between the current measured value of the control variable and the target range in the previous sampling period. L ( x- 2) This represents the difference between the current measured value of the control variable and the target range within the first two sampling periods. K p This is the proportionality coefficient. K i The integral coefficient is... K d is the differential coefficient.

2. The distillation column control method according to claim 1, characterized in that, The determination of the current operating status of the distillation column based on the comparison between the current measured values ​​and the target range of the distillation column's operating parameters includes: If the current measured value of the bottom liquid level is determined to be lower than the target lower limit of the bottom liquid level, the current working state is determined to be the feeding stage; If the current measured value of the bottom liquid level is greater than the target lower limit of the bottom liquid level, the current working state is determined to be the heating stage; If the current measured value of the top production flow rate is greater than the target lower limit value of the top production flow rate, the current working state is determined to be the production stage.

3. The distillation column control method according to claim 2, characterized in that, The determination of the control variables and controlled variables under the current operating state includes: The control variable for the feeding stage is determined as the tower bottom temperature, and the main controlled variable corresponding to the tower bottom temperature during the feeding stage is determined as the opening degree of the bottom steam valve.

4. The distillation column control method according to claim 3, characterized in that, The secondary controlled variables corresponding to the bottom temperature of the column during the feeding stage are determined as the set temperature of the preheater and the opening degree of the inlet valve of the distillation column.

5. The distillation column control method according to claim 2, characterized in that, The determination of the control variables and controlled variables under the current operating state also includes: The control variables for the heating stage are determined as the bottom liquid level, bottom temperature, stripping section temperature, and rectifying section temperature; The main controlled variable corresponding to the bottom liquid level during the heating stage is determined as the opening degree of the inlet valve of the distillation column. The main controlled variables corresponding to the temperature of the stripping section during the heating stage are determined as the opening degree of the bottom steam valve and the power of the stripping section insulation jacket. The main controlled variables corresponding to the temperature of the rectification section during the heating stage are determined as the opening degree of the bottom steam valve and the power of the insulation jacket of the rectification section.

6. The distillation column control method according to claim 5, characterized in that, The secondary controlled variable corresponding to the bottom liquid level during the heating stage is determined as the bottom outlet valve opening; and the secondary controlled variable corresponding to the bottom temperature during the heating stage is determined as the preheater set temperature and the distillation column inlet valve opening.

7. The distillation column control method according to claim 2, characterized in that, The determination of the control variables and controlled variables under the current operating state also includes: The control variables for the extraction stage are defined as: bottom liquid level, bottom temperature, stripping section temperature, rectifying section temperature, top product composition, and top extraction flow rate. The main controlled variable corresponding to the bottom liquid level in the extraction stage is determined as the inlet valve opening of the distillation column; The main controlled variable corresponding to the temperature of the stripping section during the extraction stage is determined as the power of the stripping section insulation jacket. The main controlled variable corresponding to the temperature of the rectification section during the extraction stage is determined as the power of the insulation jacket of the rectification section. The main controlled variable corresponding to the composition of the top product in the extraction stage is determined as the reflux ratio of the distillation column; The main controlled variable corresponding to the top production flow rate during the production stage is determined as the opening degree of the bottom steam valve.

8. The distillation column control method according to claim 7, characterized in that, The secondary controlled variable corresponding to the bottom liquid level during the extraction stage is determined as the bottom outlet valve opening; and the secondary controlled variable corresponding to the bottom temperature during the extraction stage is determined as the preheater set temperature and the distillation column inlet valve opening.

9. The distillation column control method according to claim 1, characterized in that, When the current measured value of the control variable is less than the target lower limit of the control variable, or when the current measured value of the control variable is greater than the target upper limit of the control variable, the proportional coefficient of the main controlled variable is determined as the initial value. When the current measured value of the control variable is greater than the target lower limit of the control variable but less than the target upper limit of the control variable, the proportional coefficient of the main controlled variable is determined as the product of the initial value and the limiting factor. The formula for calculating the limiting factor is: ； in, θ As a limiting factor, L 0 represents the current measured value of the control variable. L 1 represents the target lower limit value of the control variable. L 2 represents the target upper limit value of the control variable. k This is a user-defined constant, and 0.2 < k <1.

10. The distillation column control method according to claim 1, characterized in that, The proportional coefficient of the secondary controlled variable is determined as the product of the initial value and the relative coefficient, with the relative coefficient ranging from 0.2 to 0.

9.

11. A terminal device, characterized in that, The terminal device includes a processor and a memory, wherein the memory stores at least one computer program, which is loaded and executed by one or more of the processors to enable the terminal device to implement the distillation column control method according to any one of claims 1 to 10.

12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one piece of program code, which is loaded and executed by a processor to enable the computer to implement the distillation column control method according to any one of claims 1 to 10.

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