Self-adaptive control method and system based on semi-intermittent device-solvent separation tower

Abstract

The invention discloses a self-adaptive control method and system based on a semi-intermittent device-solvent separation tower, and relates to the technical field of solvent separation.The real-time reflux liquid level value of a reflux tank connected with the output end of the solvent separation tower is obtained, the reflux tank refluxes a low-boiling-point solvent to the solvent separation tower, gaseous distillates are cooled, and the low-boiling-point solvent is separated from the solvent separation tower; the high-boiling-point solvent is liquefied, the tower kettle evaporation capacity of the solvent separation tower is calculated according to the real-time reflux liquid level numerical value and a preset formula, the temperature rise rate of the tower kettle of the solvent separation tower is calculated and controlled according to the tower kettle evaporation capacity, and in the control process, the temperature rise rate of the tower kettle of the solvent separation tower is calculated by integrating manual operation and historical data experience. The evaporation capacity is represented by the rising rate of the liquid level of the reflux tank, the optimal parameters of the rising rate of the temperature required in the operation period of the solvent separation tower and the liquid level change rate of the reflux tank are summarized and sorted out, the problem that the temperature and liquid level change cannot be analyzed and calculated in real time by manual operation is solved, and the control process is fine and stable.

Description

Technical Field

[0001] The invention relates to the technical field of solvent separation, and in particular to an adaptive control method and system based on a semi-batch device-solvent separation tower. Background Art

[0002] In the traditional chemical production process, when it is necessary to process some raw materials that need to be processed in batches, or have low output, or whose composition changes frequently, intermittent or semi-batch distillation devices are often used.

[0003] There are many by-products produced in the solvent separation pre-process device, resulting in a variety of composition changes, so a semi-batch separation tower is used to separate them and reuse them. If the product separated by the device is unqualified, the solvent may cause a serious quality accident when it is put back into production; if the device processing capacity does not meet the corresponding requirements, the solvent will be accumulated, causing the device to shut down. The above two situations will not only cause losses to the company, but may even cause production accidents. Therefore, the adaptive control of the solvent separation tower is extremely important, which can greatly reduce the risk of enterprise production.

[0004] At present, the control of the solvent separation tower is mainly to observe the boiling situation and temperature of the separation tower kettle by camera and adjust them in stages. Different temperature setting values ​​are set at different stages to adjust the steam. When the temperature and liquid level reach a certain value, the feed and steam are stopped and the plant is shut down. However, in the normal production process, due to the fluctuation of high waste content or the unreasonable setting value of the tower kettle temperature, the residual liquid may contain more solvent, or the temperature may rise faster, resulting in a small solvent processing volume, unqualified products, and high energy consumption of the device. If the processing volume does not meet the requirements for a long time, the storage volume of the solvent tank will increase sharply, and the previous device will be forced to stop, causing significant property losses.

[0005] Therefore, the existing control has the following defects:

[0006] Solvent separation is a non-steady-state semi-batch process. The bottom of the tower is continuously fed but no material is withdrawn. As high-boiling substances continue to accumulate in the bottom of the tower, the required temperature of the solvent bottom becomes higher. However, the composition of high-boiling substances is complex and changeable, and the high-boiling substance content has a nonlinear relationship with the required distillation temperature, causing the device to often be out of balance. Summary of the invention

[0007] The purpose of the present invention is to provide an adaptive control method and system based on a semi-batch device-solvent separation tower, so as to control the operating mode of the temperature change rate and the liquid level change rate of the tower bottom, so as to more intuitively display the influence of high boiling points in the tower bottom on the temperature required for distillation. When the liquid level rising rate is unreasonable, the temperature change rate can be adjusted according to the formula to achieve the effect of adaptive control, and the control process is more precise and stable.

[0008] In order to solve the above technical problems, an embodiment of the present invention provides an adaptive control method based on a semi-batch device-solvent separation tower, comprising:

[0009] S1: obtaining a real-time reflux liquid level value of a reflux tank connected to an output end of a solvent separation tower, and refluxing the cooled solvent in the reflux tank to the solvent separation tower, cooling the gaseous distillate of the solvent separation tower, and liquefying the distillate of the solvent having a boiling point higher than that of the reflux;

[0010] S2: Calculate the evaporation amount of the bottom of the solvent separation tower according to the real-time reflux liquid level value and formula (1);

[0011] in, (1),

[0012] Among them, F E is the evaporation amount of the tower bottom, L rt1 is the liquid level value of the reflux tank at the current moment, L rt2 is the liquid level value of the reflux tank n minutes ago, R r is the radius of the reflux tank, ρ1 is the solvent density of the reflux tank;

[0013] S3: controlling the temperature rise rate of the bottom of the solvent separation tower according to the evaporation amount of the bottom of the tower and in combination with formulas (2), (3) and (4);

[0014] (2);

[0015] (3);

[0016] (4);

[0017] Wherein, ΔT is the temperature rise rate calculated based on the evaporation amount of the tower bottom; F E F is the evaporation amount of the tower bottom; a is the feed amount of crude solvent; ω w ω is the water content of the crude solvent entering the solvent separation tower; a is the content of the solvent in the crude solvent; K3 is the conversion coefficient of heat and temperature calculated based on historical data and physical properties; ΔT max is the maximum value of the temperature change allowed after the change, ΔT max_t1 ΔT is the maximum value of the temperature change allowed after the change at time t1; min is the minimum value of the temperature change allowed after the change, ΔT min_t1 It is the minimum value of the temperature change allowed after the change at time t1.

[0018] Wherein, after S3, it also includes:

[0019] S4: Determine whether the liquid level of the reflux tank is greater than the production value and no production is done;

[0020] If not, S5: open the production valve of the reflux tank until the production is completed and then close the production valve; if yes, go to S2.

[0021] Wherein, after S3, it also includes:

[0022] S6: Calculating the steam amount of the bottom reboiler for heating the solvent separation tower according to the current temperature value of the solvent separation tower and formula (5);

[0023] (5);

[0024] Among them, F LS is the steam volume; T t1 is the temperature of the bottom of the solvent separation tower at the current moment; T t2 is the temperature of the bottom of the solvent separation tower n minutes ago; K1 is the gain of the steam volume and temperature change obtained by modeling based on historical data.

[0025] Wherein, after S3, it also includes:

[0026] S7: Calculating the feed amount to the solvent separation tower according to the current liquid level value of the solvent separation tower and formula (6);

[0027] in, (6);

[0028] Among them, F a is the crude solvent feed amount of the solvent separation tower; L t1 is the liquid level value of the bottom of the solvent separation tower at the current moment; L t1 is the liquid level value of the bottom of the solvent separation tower n minutes ago; ΔL max ΔL is the maximum value of the allowable liquid level change; min is the minimum value of the allowed liquid level change; K2 is the gain of solvent feed amount and liquid level change obtained by modeling based on historical data.

[0029] Wherein, after S3, it also includes:

[0030] Display the real-time reflux liquid level value of the reflux drum, the evaporation amount of the tower bottom, the solvent density, the liquid level of the reflux drum, the temperature value of the solvent separation tower, the steam amount, the liquid level value of the solvent separation tower and the feed amount of the solvent separation tower.

[0031] Wherein, after S3, it also includes:

[0032] The real-time pressure value of the tower bottom of the solvent separation tower is detected, and a pressure crossing alarm message is issued after the real-time pressure value reaches a pressure threshold.

[0033] In addition, an embodiment of the present application further provides an adaptive control system based on a semi-batch device-solvent separation tower, which adopts the adaptive control method based on a semi-batch device-solvent separation tower as described above, including a solvent separation tower, a tower bottom reboiler, a condenser, a reflux tank and a controller, wherein the first input end of the solvent separation tower is used to input a crude solvent, which is output to the tower bottom reboiler through a first output end arranged at the bottom for heating and vaporization, and then output to the solvent separation tower and output through a second output end of the solvent separation tower, and is output to the reflux tank for storage after cooling and liquefaction through the condenser, and the reflux tank is connected to the second input end of the solvent separation tower, and is used to reflux the stored solvent from the top of the solvent separation tower to the solvent separation tower, and the controller calculates the evaporation amount of the tower bottom according to the reflux liquid level value of the reflux tank, controls the temperature rise rate of the tower bottom of the solvent separation tower, and controls the steam amount of the tower bottom reboiler for heating the solvent separation tower according to the temperature value of the solvent separation tower, and controls the feed amount of the solvent separation tower according to the liquid level value of the solvent separation tower.

[0034] Wherein, it also includes a pressure sensor arranged in the solvent separation tower for detecting pressure information in the solvent separation tower, and the pressure sensor is connected to the controller and transmits the pressure information to the controller.

[0035] It also includes a display connected to the controller, which is used to display the real-time reflux liquid level value of the reflux tank, the evaporation amount of the tower bottom, the solvent density, the liquid level of the reflux tank, the temperature value of the solvent separation tower, the pressure information, the steam amount, the liquid level value of the solvent separation tower and the feed amount of the solvent separation tower.

[0036] It also includes a coefficient setting module connected to the controller, which is used to input the conversion coefficient of heat and temperature, the gain of steam volume and temperature change, and the gain of solvent feed volume and liquid level change.

[0037] The semi-batch device-solvent separation tower adaptive control method and system provided in the embodiments of the present invention have the following advantages compared with the prior art:

[0038] The semi-batch device-solvent separation tower adaptive control method and system provided in the embodiment of the present invention obtains the real-time reflux liquid level value of the reflux tank connected to the output end of the solvent separation tower, calculates the evaporation amount of the bottom of the solvent separation tower according to the real-time reflux liquid level value and a preset formula, and calculates and controls the temperature rise rate of the bottom of the solvent separation tower according to the evaporation amount of the bottom. In the control process, the adaptive control effect is achieved by integrating manual operation and historical data experience, and adaptively adjusting relevant parameters according to the evaporation amount, so that the control process is more precise and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A schematic flow chart of steps of an embodiment of the semi-batch device-solvent separation tower adaptive control method provided by the present invention;

[0041] Figure 2 A schematic structural diagram of another embodiment of the semi-batch device-solvent separation tower adaptive control method provided by the present invention;

[0042] Figure 3 A schematic diagram of the structure of an embodiment of the present invention based on a semi-batch device - solvent separation tower adaptive control system;

[0043] Among them, 10 is a solvent separation tower, 20 is a reflux tank, 30 is a condenser, and 40 is a tower bottom reboiler. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Please refer to Figure 1-Figure 3 , Figure 1 A schematic flow chart of steps of an embodiment of the semi-batch device-solvent separation tower adaptive control method provided by the present invention; Figure 2 A schematic structural diagram of another embodiment of the semi-batch device-solvent separation tower adaptive control method provided by the present invention; Figure 3A schematic structural diagram of an embodiment of the semi-batch device-solvent separation tower adaptive control system provided by the present invention.

[0046] In a specific embodiment, the semi-batch device-solvent separation tower adaptive control method comprises:

[0047] S1: obtaining a real-time reflux liquid level value of a reflux tank connected to an output end of a solvent separation tower, and refluxing the cooled solvent in the reflux tank to the solvent separation tower, cooling the gaseous distillate of the solvent separation tower, and liquefying the distillate of the solvent having a boiling point higher than that of the reflux;

[0048] S2: Calculate the evaporation amount of the bottom of the solvent separation tower according to the real-time reflux liquid level value and formula (1);

[0049] in, (1),

[0050] Among them, F E is the evaporation amount of the tower bottom, L rt1 is the liquid level value of the reflux tank at the current moment, L rt2 is the liquid level value of the reflux tank n minutes ago, R r is the radius of the reflux tank, ρ1 is the solvent density of the reflux tank;

[0051] S3: controlling the temperature rise rate of the bottom of the solvent separation tower according to the evaporation amount of the bottom of the tower and in combination with formulas (2), (3) and (4);

[0052] (2);

[0053] (3);

[0054] (4);

[0055] Wherein, ΔT is the temperature rise rate calculated based on the evaporation amount of the tower bottom; F E F is the evaporation amount of the tower bottom; a is the feed amount of crude solvent; ω w ω is the water content of the crude solvent entering the solvent separation tower; a is the content of the solvent in the crude solvent; K3 is the conversion coefficient of heat and temperature calculated based on historical data and physical properties; ΔT max is the maximum value of the temperature change allowed after the change, ΔT max_t1 ΔT is the maximum value of the temperature change allowed after the change at time t1; minis the minimum value of the temperature change allowed after the change, ΔT min_t1 It is the minimum value of the temperature change allowed after the change at time t1.

[0056] By acquiring the real-time reflux liquid level value of the reflux tank connected to the output end of the solvent separation tower, the evaporation amount of the bottom of the solvent separation tower is calculated according to the real-time reflux liquid level value and the preset formula, and the temperature rise rate of the bottom of the solvent separation tower is calculated and controlled according to the evaporation amount of the bottom. In the control process, by integrating manual operation and historical data experience, a method of characterizing the evaporation amount by the rising rate of the reflux tank liquid level is established, and at the same time, the liquid level rising rate result is applied to the temperature rising rate. When the raw material composition changes, adaptive control is achieved by changing the temperature rising rate to correct the temperature change rate. When the liquid level rising rate is unreasonable, the temperature change rate can be adjusted according to the formula to achieve the effect of adaptive control, and the control process is more precise and stable.

[0057] In this application, after the solvent is collected in the reflux tank, a portion of it needs to be returned to the solvent separation tower. However, the liquid level in the reflux tank will continue to rise, and its storage capacity is limited, so appropriate discharge is required.

[0058] The reason why the solvent in the reflux tank is returned to the solvent separation tower in the present application is to prevent some high-boiling-point substances therein from distilling out and reaching the reflux tank due to excessively high temperature. In the process of returning the solvent, the high-boiling-point substances are cooled so that they return in liquid form, thereby reducing the possibility of high-boiling-point substances distilling out and improving the solvent separation efficiency.

[0059] In one embodiment of the present application, after S3, the method further includes:

[0060] S4: Determine whether the liquid level of the reflux tank is greater than the production value and no production is done;

[0061] If not, S5: open the production valve of the reflux tank until the production is completed and then close the production valve; if yes, go to S2.

[0062] By opening the production valve of the reflux tank when the liquid level in the reflux tank is greater than the production value and no production has been made, and closing the production valve after production, this process can not only achieve the reflux of the solvent, but also ensure that the liquid level in the reflux tank is maintained at a safe value, thereby improving the safety of operation and the efficiency of solvent extraction.

[0063] There is no limitation on the extraction value in this application, and it can be set uniformly or set by oneself.

[0064] In order to further improve the solvent separation efficiency and avoid making the temperature of the solvent separation tower too high to cause a high boiling point, after S3, the following steps are further included:

[0065] S6: Calculating the steam amount of the bottom reboiler for heating the solvent separation tower according to the current temperature value of the solvent separation tower and formula (5);

[0066] (5);

[0067] Among them, F LS is the steam volume; T t1 is the temperature of the bottom of the solvent separation tower at the current moment; T t2 is the temperature of the bottom of the solvent separation tower n minutes ago; K1 is the gain of the steam volume and temperature change obtained by modeling based on historical data.

[0068] By acquiring the temperature value of the solvent separation tower in real time and calculating the steam amount of the tower bottom reboiler for heating the solvent separation tower according to the corresponding formula, the temperature of the solvent separation tower can be accurately controlled.

[0069] It should be pointed out that the present application includes but is not limited to the above-mentioned steam volume calculation formula, and other formulas may also be used, and the gain value therein may also be obtained by modeling and the like, and it may be a constant value or a variable value.

[0070] In addition, in the present application, as the separation continues, the amount of high-boiling point substances will continue to increase, and thus the liquid level value of the solvent separation tower will continue to increase. In order to avoid excessive feed amount causing heat dilution, the overall instantaneous temperature is too low, the separation efficiency is too low, and the feed amount will result in low separation efficiency.

[0071] In order to improve the separation efficiency, in one embodiment, after S3, the method further includes:

[0072] S7: Calculating the feed amount to the solvent separation tower according to the current liquid level value of the solvent separation tower and formula (6);

[0073] in, (6);

[0074] Among them, F a is the crude solvent feed amount of the solvent separation tower; L t1 is the liquid level value of the bottom of the solvent separation tower at the current moment; L t1 is the liquid level value of the bottom of the solvent separation tower n minutes ago; ΔL max ΔL is the maximum value of the allowable liquid level change; min is the minimum value of the allowed liquid level change; K2 is the gain of solvent feed amount and liquid level change obtained by modeling based on historical data.

[0075] By monitoring the liquid level of the solvent separation tower, based on historical values ​​and the type of solvent in the crude solvent, the high boiling point content can be obtained according to the actual liquid level value, thereby controlling the feed amount and improving the separation efficiency.

[0076] For example, when the actual liquid level value is low, it means that the stock of high-boiling-point substances is small. At this time, if the feed amount is large, the temperature after the overall mixing will be low due to the small stock of high-boiling-point substances already existing. On the contrary, when the actual liquid level value is high, it means that the stock of high-boiling-point substances is large. Even if the feed amount is large, the overall temperature after mixing will not be too low. The low-boiling-point solvent can be vaporized by heating, and the reduction in the efficiency of solvent separation is limited.

[0077] In order to further improve management efficiency, in one embodiment, after S3, the following steps are further included:

[0078] Display the real-time reflux liquid level value of the reflux drum, the evaporation amount of the tower bottom, the solvent density, the liquid level of the reflux drum, the temperature value of the solvent separation tower, the steam amount, the liquid level value of the solvent separation tower and the feed amount of the solvent separation tower.

[0079] By setting the display to show the operating parameters of related equipment, its operating data can be obtained in real time to improve operating efficiency.

[0080] The present application does not limit the data display method, display device, etc. It can be that the operating data of the required equipment is displayed separately on the display as needed, or different data can be displayed in turn, or the operating data of different equipment can be displayed altogether.

[0081] In order to further ensure the safety of equipment operation, after S3, the following steps are also included:

[0082] The real-time pressure value of the tower bottom of the solvent separation tower is detected, and a pressure crossing alarm message is issued after the real-time pressure value reaches a pressure threshold.

[0083] By real-time detection of the pressure value of the bottom of the solvent separation tower, the separation of high-boiling-point solvents due to excessive heating temperature can be avoided, thereby improving the safety of equipment operation.

[0084] The present application does not limit the pressure threshold and setting method.

[0085] In addition, the embodiment of the present application further provides an adaptive control system based on a semi-batch device-solvent separation tower 10, which adopts the adaptive control method based on the semi-batch device-solvent separation tower 10 as described above, including a solvent separation tower 10, a tower bottom reboiler 40, a condenser 30, a reflux tank 20 and a controller, wherein the first input end of the solvent separation tower 10 is used to input a crude solvent, which is output to the tower bottom reboiler 40 through a first output end arranged at the bottom for heating and vaporization, and then output to the solvent separation tower 10 and output through a second output end of the solvent separation tower 10, and then cooled and liquefied by the condenser 30 and output to the reflux tank 20. The reflux tank 20 is connected to the second input end of the solvent separation tower 10, and is used to reflux the stored solvent from the top of the solvent separation tower 10 to the solvent separation tower 10. The controller calculates the evaporation amount of the tower bottom according to the reflux liquid level value of the reflux tank 20, controls the temperature rise rate of the tower bottom of the solvent separation tower 10, controls the steam amount of the tower bottom reboiler 40 for heating the solvent separation tower 10 according to the temperature value of the solvent separation tower 10, and controls the feed amount of the solvent separation tower 10 according to the liquid level value of the solvent separation tower 10.

[0086] Since the adaptive control system based on the semi-batch device-solvent separation tower 10 adopts the adaptive control method based on the semi-batch device-solvent separation tower 10 as described above, and has the same beneficial effects as the adaptive control method based on the semi-batch device-solvent separation tower 10 as described above, the present application will not elaborate on this.

[0087] In order to further improve the safety of the use of the solvent separation tower 10 and avoid poor separation safety due to excessive pressure or poor separation efficiency due to too low pressure, in one embodiment, the semi-batch device-solvent separation tower 10 adaptive control system also includes a pressure sensor arranged in the solvent separation tower 10 for detecting pressure information in the solvent separation tower 10, and the pressure sensor is connected to the controller and transmits the pressure information to the controller.

[0088] By setting a pressure sensor to obtain the pressure information in the solvent separation tower 10 in real time, it is possible to ensure that the amount of gas is kept within a certain range and will not be too much, thereby ensuring the reliability of operation, and will not be too little and will not reduce the solvent separation efficiency.

[0089] In this application, an alarm device can also be set. If the pressure, temperature, liquid level, feed volume, steam volume, etc. exceed the threshold, an alarm can also be issued, such as a light indicator light, a sound indicator light, a short message, etc.

[0090] In order to further improve management efficiency, in one embodiment, the adaptive control system based on the semi-batch device-solvent separation tower 10 also includes a display connected to the controller, which is used to display the real-time reflux liquid level value of the reflux tank 20, the tower bottom evaporation amount, the solvent density, the liquid level of the reflux tank 20, the temperature value of the solvent separation tower 10, the pressure information, the steam amount, the liquid level value of the solvent separation tower 10 and the feed amount of the solvent separation tower 10.

[0091] By displaying the operating parameters of relevant equipment on the display, its operating data can be obtained in real time to improve operating efficiency.

[0092] Since the coefficients in the relevant formulas are different for different devices, and may even change with the change of the model, in one embodiment, the adaptive control system based on the semi-batch device-solvent separation tower 10 also includes a coefficient setting module connected to the controller, which is used to input the conversion coefficient of heat and temperature, the gain of steam volume and temperature change, and the gain of solvent feed volume and liquid level change.

[0093] By setting the relevant heat and temperature conversion coefficients, the gain of steam volume and temperature change, and the gain of solvent feed volume and liquid level change, the parameters can be flexibly set. The setting of the parameters can be automatically selected according to the model or by the staff. The parameters can be specific values ​​or corresponding formulas.

[0094] The crude solvent of the solvent and other high-boiling substances in the present application enters the solvent separation tower 10 from the middle of the tower body, and flows into the bottom of the tower kettle after multiple heat and mass transfer. The tower kettle is provided with heat by steam, and the temperature of the tower kettle is controlled to evaporate the solvent and water. After the evaporated material is fully in vapor-liquid contact with the feed and reflux material, it flows into the reflux tank 20 after condensation in the tower bottom condenser 30. A part of the solvent in the reflux tank 20 is refluxed according to the proportion, and the other part is discharged to the corresponding storage tank for standby use. When the high-boiling substances in the tower kettle accumulate to a certain amount, the tower kettle liquid level and the required distillation temperature continue to rise therewith, and the feed is stopped at this time, and the remaining solvent is evaporated and the heating is stopped, and the residual liquid in the tower kettle is discharged.

[0095] In the present application, the solvent refluxed from the reflux tank 20 is a low-boiling-point solvent, a liquid. The reflux liquid returns to the tower from the top of the tower and fully contacts the gas phase rising after being heated in the tower bottom. The heavy components in the ascending gas are condensed after being cooled, and the light components in the descending liquid are vaporized after absorbing heat. Each contact is a simple distillation process. Through repeated condensation and vaporization, the light and heavy components can be separated more effectively, and the accuracy of product separation can be increased.

[0096] In the present application, historical data is used for calculation, and given different temperature rise rate ranges in different stages of the system, the temperature of the tower bottom is controlled by adjusting the temperature rise rate.

[0097] The discharge mode of the solvent in the reflux tank 20 is changed from continuous discharge to automatic intermittent discharge by the system, so that the system can calculate the evaporation amount of the device within a unit cycle, thereby adjusting the rising rate of the temperature in the tower kettle to achieve adaptive control.

[0098] Through the historical operation data and the change of temperature rise rate, the change of the content of high boiling materials in the reaction raw materials and the tower bottom, different tower bottom liquid level rise rates are set and the amount of raw materials added is controlled to achieve the best distillation effect.

[0099] The evaporation rate is calculated as follows:

[0100] (1),

[0101] Among them, F E is the evaporation amount of the tower bottom, L rt1 is the liquid level value of the reflux tank 20 at the current moment, L rt2 is the liquid level value of the reflux tank 20n minutes ago, R r is the radius of the reflux tank 20, and ρ1 is the solvent density of the reflux tank 20, which is read by an online density meter.

[0102] The steam adjustment is calculated as follows:

[0103] (5);

[0104] Among them, F LS is the steam volume; T t1 T is the temperature of the bottom of the solvent separation tower 10 at the current moment; t2 is the temperature of the bottom of the solvent separation tower 10 n minutes ago; K1 is the gain of the steam volume and temperature change obtained by modeling based on historical data;

[0105] The feed adjustment amount is as follows:

[0106] (6);

[0107] Among them, F a is the crude solvent feed amount of the solvent separation tower 10; L t1 L is the liquid level value of the bottom of the solvent separation tower 10 at the current moment; t1 is the liquid level value of the bottom of the solvent separation tower 10 n minutes ago; ΔL max ΔL is the maximum value of the allowable liquid level change;min is the minimum value of the allowed liquid level change; K2 is the gain of solvent feed amount and liquid level change obtained by modeling based on historical data;

[0108] Change the set temperature rise rate according to the evaporation amount as follows:

[0109] (2);

[0110] (3);

[0111] (4);

[0112] Wherein, ΔT is the temperature rise rate calculated based on the evaporation amount of the tower bottom; F E F is the evaporation amount of the tower bottom; a is the feed amount of crude solvent; ω w ω is the water content of the crude solvent entering the solvent separation tower 10; a is the content of the solvent in the crude solvent; K3 is the conversion coefficient of heat and temperature calculated based on historical data and physical properties; ΔT max is the maximum value of the temperature change allowed after the change, ΔT max_t1 ΔT is the maximum value of the temperature change allowed after the change at time t1; min is the minimum value of the temperature change allowed after the change, ΔT min_t1 It is the minimum value of the temperature change allowed after the change at time t1.

[0113] The above-mentioned method and system in the present application are mainly based on the data acquisition software integrating manual operation and historical data experience; an operation mode of controlling the temperature change rate and liquid level change rate of the tower bottom is established, and the influence of the high boiling point in the tower bottom on the temperature required for distillation is more intuitively displayed; a method of characterizing the evaporation amount by the rising rate of the liquid level of the reflux tank 20 is established, and at the same time, the liquid level rising rate result is applied to the temperature rising rate, and when the raw material composition changes, the temperature rising rate is changed to achieve the effect of adaptive control.

[0114] The temperature in the tower kettle is controlled by using the temperature change rate, the liquid level rise rate in the reflux tank 20 is used to characterize the evaporation amount, the temperature change rate is corrected, and the control of the solvent separation tower 10 is standardized and intelligent. Compared with the original manual operation process, it has the following advantages:

[0115] The temperature and liquid level in the tower kettle are controlled by changing the temperature and liquid level by changing the rate of change control, so that the influence of the high boiling point in the tower kettle on the distillation temperature can be reflected in the whole operation cycle of the solvent separation tower 10;

[0116] The rising rate of the liquid level in the reflux tank 20 is used to characterize the evaporation amount. When the rising rate of the liquid level is unreasonable, the temperature change rate can be adjusted according to the formula; when the device is receiving solvents with different high-boiling content, the relevant parameters are automatically adjusted to achieve adaptive control.

[0117] The more sophisticated and stable characteristics of the program provide more sensitive and stable control for solvent treatment, reduce the high solvent content in the residual liquid in the tower kettle or the unqualified crude solvent product, increase the operation cycle and solvent treatment capacity of the device, and save some labor.

[0118] We deeply explored the potential value of historical data and realized adaptive control by collecting and analyzing DCS underlying data for up to one year.

[0119] The invention of the adaptive control of the solvent separation tower 10 of the semi-batch device in the chemical production process uses, but is not limited to, the APC expert controller module as the automatic control technology operation platform. Accordingly, the operation platform / environment also includes: the sequential control logic module provided by the DCS; other control software connected to the DCS through the OPC protocol, etc.

[0120] In summary, the semi-batch device-solvent separation tower adaptive control method and system provided in the embodiment of the present invention obtains the real-time reflux liquid level value of the reflux tank connected to the output end of the solvent separation tower, calculates the evaporation amount of the bottom of the solvent separation tower according to the real-time reflux liquid level value and a preset formula, and calculates and controls the temperature rise rate of the bottom of the solvent separation tower according to the evaporation amount of the bottom. In the control process, by integrating manual operation and historical data experience, a method for characterizing the evaporation amount by the rising rate of the reflux tank liquid level is established, and the relevant parameters are adaptively adjusted according to the evaporation amount, so as to achieve the effect of adaptive control, and the control process is more precise and stable.

[0121] The above is a detailed introduction to the adaptive control method and system based on the semi-batch device-solvent separation tower provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A semi-batch device-solvent separation tower adaptive control method, characterized in that: include: S1: obtaining a real-time reflux liquid level value of a reflux tank connected to an output end of a solvent separation tower, and refluxing the cooled solvent in the reflux tank to the solvent separation tower, cooling the gaseous distillate of the solvent separation tower, and liquefying the distillate of the solvent having a boiling point higher than that of the reflux; S2: Calculate the evaporation amount of the bottom of the solvent separation tower according to the real-time reflux liquid level value and formula (1); in, (1), Among them, F E is the evaporation amount of the tower bottom, L rt1 is the liquid level value of the reflux tank at the current moment, L rt2 is the liquid level value of the reflux tank n minutes ago, R r is the radius of the reflux tank, ρ1 is the solvent density of the reflux tank; S3: controlling the temperature rise rate of the bottom of the solvent separation tower according to the evaporation amount of the bottom of the tower and in combination with formulas (2), (3) and (4); （2）； （3）； （4）； Wherein, ΔT is the temperature rise rate calculated based on the evaporation amount of the tower bottom; F E F is the evaporation amount of the tower bottom; a is the feed amount of crude solvent; ω w ω is the water content of the crude solvent entering the solvent separation tower; a is the content of the solvent in the crude solvent; K3 is the conversion coefficient of heat and temperature calculated based on historical data and physical properties; ΔT max is the maximum value of the temperature change allowed after the change, ΔT max_t1 ΔT is the maximum value of the temperature change allowed after the change at time t1; min is the minimum value of the temperature change allowed after the change, ΔT min_t1 It is the minimum value of the temperature change allowed after the change at time t1.

2. The method for adaptive control based on a semi-batch device-solvent separation tower according to claim 1, characterized in that: After S3, it also includes: S4: Determine whether the liquid level of the reflux tank is greater than the production value and no production is done; If not, S5: open the production valve of the reflux tank until the production is completed and then close the production valve; if yes, go to S2.

3. The method for adaptive control based on a semi-batch device-solvent separation tower according to claim 2, characterized in that: After S3, it also includes: S6: Calculating the steam amount of the bottom reboiler for heating the solvent separation tower according to the current temperature value of the solvent separation tower and formula (5); （5）； Among them, F LS is the steam volume; T t1 is the temperature of the bottom of the solvent separation tower at the current moment; T t2 is the temperature of the bottom of the solvent separation tower n minutes ago; K1 is the gain of the steam volume and temperature change obtained by modeling based on historical data.

4. The method for adaptive control based on a semi-batch device-solvent separation tower according to claim 3, characterized in that: After S3, it also includes: S7: Calculating the feed amount to the solvent separation tower according to the current liquid level value of the solvent separation tower and formula (6); in, (6); Among them, F a is the crude solvent feed amount of the solvent separation tower; L t1 is the liquid level value of the bottom of the solvent separation tower at the current moment; L t1 is the liquid level value of the bottom of the solvent separation tower n minutes ago; ΔL max ΔL is the maximum value of the allowable liquid level change; min is the minimum value of the allowed liquid level change; K2 is the gain of solvent feed amount and liquid level change obtained by modeling based on historical data.

5. The method for adaptive control based on a semi-batch device-solvent separation tower according to claim 4, characterized in that: After S3, it also includes: Display the real-time reflux liquid level value of the reflux drum, the evaporation amount of the tower bottom, the solvent density, the liquid level of the reflux drum, the temperature value of the solvent separation tower, the steam amount, the liquid level value of the solvent separation tower and the feed amount of the solvent separation tower.

6. The method for adaptive control based on a semi-batch device-solvent separation tower according to claim 1, characterized in that: After S3, it also includes: The real-time pressure value of the tower bottom of the solvent separation tower is detected, and a pressure crossing alarm message is issued after the real-time pressure value reaches a pressure threshold.

7. An adaptive control system based on a semi-batch device-solvent separation tower, characterized in that: The method for adaptively controlling a semi-batch device-solvent separation tower according to any one of claims 1 to 6 is adopted, comprising a solvent separation tower, a tower bottom reboiler, a condenser, a reflux tank and a controller, wherein the first input end of the solvent separation tower is used to input a crude solvent, which is output to the tower bottom reboiler through a first output end arranged at the bottom for heating and vaporization, and then output to the solvent separation tower and output through a second output end of the solvent separation tower, and then output to the reflux tank for storage after cooling and liquefaction through the condenser, the reflux tank is connected to the second input end of the solvent separation tower, and is used to reflux the stored solvent from the top of the solvent separation tower to the solvent separation tower, the controller calculates the evaporation amount of the tower bottom according to the reflux liquid level value of the reflux tank, controls the temperature rise rate of the tower bottom of the solvent separation tower, controls the steam amount of the tower bottom reboiler for heating the solvent separation tower according to the temperature value of the solvent separation tower, and controls the feed amount of the solvent separation tower according to the liquid level value of the solvent separation tower.

8. The semi-batch device-solvent separation tower adaptive control system according to claim 7, characterized in that: It also includes a pressure sensor disposed in the solvent separation tower for detecting pressure information in the solvent separation tower. The pressure sensor is connected to the controller and transmits the pressure information to the controller.

9. The semi-batch device-solvent separation tower adaptive control system according to claim 8, characterized in that: It also includes a display connected to the controller, which is used to display the real-time reflux liquid level value of the reflux tank, the evaporation amount of the tower bottom, the solvent density, the liquid level of the reflux tank, the temperature value of the solvent separation tower, the pressure information, the steam amount, the liquid level value of the solvent separation tower and the feed amount of the solvent separation tower.

10. The semi-batch device-solvent separation tower adaptive control system according to claim 9, characterized in that: It also includes a coefficient setting module connected to the controller, which is used to input the conversion coefficient of heat and temperature, the gain of steam amount and temperature change, and the gain of solvent feed amount and liquid level change.

Images