Automatic temperature control method and system for antioxidant chemical reactor

Abstract

The present application relates to the field of temperature control technology, and specifically to an automatic temperature control method and system for an antioxidant chemical reactor, the method comprising: obtaining the initial values ​​of the proportional coefficient, integral coefficient and differential coefficient of the PID algorithm, forming a parameter vector, collecting the temperature data of the antioxidant crystallization at each collection time; obtaining the temperature difference value of each temperature data, dividing the temperature difference values ​​of all temperature data into each temperature difference adjustment interval; determining the interval abnormal value of each temperature difference adjustment interval; determining the cooling rate fluctuation value of the PID algorithm based on the change trend and distribution characteristics of the interval abnormal value of all temperature difference adjustment intervals; using the fireworks algorithm to obtain the proportional coefficient, integral coefficient and differential coefficient after the PID algorithm is adjusted, obtaining the optimal compressor frequency of the compressor in the chemical reactor, and controlling the temperature of the chemical reactor. The present application aims to improve the stability of the cooling rate in the chemical reactor.

Description

Technical Field

[0001] The present application relates to the technical field of temperature control, and in particular to an automatic temperature control method and system for an antioxidant chemical reactor. Background Art

[0002] With the rapid development of polymer materials and the continuous expansion of their application fields, the industry has put forward higher requirements on the life and performance of polymer materials. Antioxidants, as additives in the preparation process of polymer materials, are mainly used to prevent the oxidation and aging of materials, improve the heat resistance, light resistance and oxygen resistance of polymer materials, delay the degradation and aging process of polymer materials products, and extend their service life.

[0003] The crystallization process is one of the most important processes for controlling the quality of antioxidant products, in which the cooling rate has a great influence on the crystal form of the antioxidant. Maintaining a stable cooling rate in the chemical reactor is a key condition to ensure that the antioxidant is fully separated from impurities and obtain a single crystal antioxidant. The traditional PID algorithm uses fixed parameter settings to adjust the temperature of the chemical reactor, ignoring the problem of fluctuations in the cooling rate caused by the crystallization heat released by the antioxidant and the change in the specific heat capacity of the saturated solution, resulting in poor stability of the cooling rate in the chemical reactor, which in turn affects the quality of the antioxidant product. Summary of the invention

[0004] In view of the above, it is necessary to provide an automatic temperature control method and system for an antioxidant chemical reactor, which improves the stability of the cooling rate in the chemical reactor compared to the traditional automatic temperature control method and system for antioxidant chemical reactors:

[0005] In a first aspect, an embodiment of the present application provides an automatic temperature control method for an antioxidant chemical reactor, the method comprising the following steps:

[0006] Obtaining initial values ​​of the proportional coefficient, integral coefficient, and differential coefficient of the PID algorithm to form a parameter vector, using the parameter vector as a reference, presetting multiple parameter vectors, and forming all parameter vectors into a parameter vector set; collecting temperature data of the antioxidant crystallization at a preset first number of collection moments;

[0007] The difference between each temperature data and its adjacent temperature data is recorded as a temperature difference value, and based on the change in the difference between the temperature difference values ​​of all temperature data and the preset ideal temperature difference value, the temperature difference values ​​of all temperature data are divided into a plurality of temperature difference adjustment intervals;

[0008] Determine the interval abnormal value of each temperature difference adjustment interval by combining the distribution of the differences between all temperature difference values ​​in each temperature difference adjustment interval and the preset ideal temperature difference value, the distribution range, and the distribution of the temperature data corresponding to the temperature difference value;

[0009] Determine the cooling rate fluctuation value of the PID algorithm based on the change trend and distribution characteristics of the abnormal values ​​in the interval;

[0010] Based on the accumulated value of the difference between the temperature difference value of the temperature data under each parameter vector and the preset ideal temperature difference value, the fitness value of each parameter vector in the parameter vector set in the fireworks algorithm is obtained; according to the fitness value, the explosion radius of each parameter vector in the parameter vector set in the fireworks algorithm is obtained, and based on the cooling rate fluctuation value and the explosion radius, the explosion position offset of each parameter vector in the parameter vector set is determined;

[0011] Based on the parameter vector set and the explosion position offset, the fireworks algorithm is used to obtain the proportional coefficient, integral coefficient and differential coefficient adjusted by the PID algorithm, the optimal compressor frequency of the compressor in the chemical reactor is obtained, and the temperature of the chemical reactor is controlled.

[0012] In one embodiment, the process of acquiring the parameter vector set is as follows:

[0013] (1) Taking each component of the current parameter vector of the PID algorithm as the center, a parameter interval of a preset length is constructed;

[0014] (2) Randomly select a positive number from each parameter interval to form a new parameter vector;

[0015] (3) Repeat step (2) until a preset second number of new parameter vectors are formed, and then end the loop;

[0016] (4) Combining the preset second number of new parameter vectors and the current parameter vector of the PID algorithm into a parameter vector set.

[0017] In one embodiment, the process of determining the temperature difference adjustment interval is as follows:

[0018] The absolute value of the difference between each temperature difference value and the preset ideal temperature difference value is used as the cooling rate error of each temperature difference value;

[0019] All cooling rate errors are arranged in time sequence, the temperature difference value where the cooling rate error is 0 is taken as the interval endpoint, and all temperature difference values ​​are divided into various temperature difference adjustment intervals.

[0020] In one embodiment, the expression of the interval outlier value is:

[0021] ; In the formula, represents the interval abnormal value of the i-th temperature difference adjustment interval; Represents the number of temperature difference values ​​in the i-th temperature difference adjustment interval; represents the cooling rate error of the jth temperature difference value in the i-th temperature difference adjustment interval; It represents the maximum value of the cooling rate error of all temperature difference values ​​in the i-th temperature difference adjustment interval; It represents the average value of the normalized values ​​of the temperature data corresponding to all temperature difference values ​​in the i-th temperature difference adjustment interval.

[0022] In one embodiment, the process of determining the cooling rate fluctuation value is as follows:

[0023] Obtain the fitting straight line of the interval outliers of all temperature difference adjustment intervals;

[0024] The expression of the cooling rate fluctuation value flu of the PID algorithm is:

[0025] ; Wherein, exp() represents an exponential function with a natural constant as the base; k represents the slope of the fitting line; r represents the number of temperature difference adjustment intervals; represents the interval abnormal value of the i-th temperature difference adjustment interval; i represents the sequence number of the temperature difference adjustment interval; β represents a preset value greater than 0.

[0026] In one embodiment, the process of determining the fitness value is:

[0027] The transfer function of the temperature model of the chemical reactor control system is obtained by the step response method;

[0028] Using each component of any parameter vector as a proportional coefficient, an integral coefficient and a differential coefficient of a PID algorithm, and obtaining the preset first number of temperature data through the transfer function simulation;

[0029] The sum of the cooling rate errors of the temperature difference values ​​of the preset first number of temperature data is used as the fitness value of any parameter vector.

[0030] In one embodiment, the explosion position offset is expressed as:

[0031] ; In the formula, Represents the explosion position offset of the nth parameter vector in the parameter vector set; It represents the explosion radius of the nth parameter vector in the fireworks algorithm in the parameter vector set; flu represents the cooling rate fluctuation value of the PID algorithm; rand() represents a random function that obeys a uniform distribution.

[0032] In one embodiment, the method for obtaining the proportional coefficient, integral coefficient and differential coefficient after the PID algorithm is adjusted is:

[0033] The parameter vector set is used as the input of the fireworks algorithm, and each new parameter vector is generated based on the explosion position offset. The components of the parameter vector output after the fireworks algorithm reaches a preset number of iterations are used as the proportional coefficient, integral coefficient and differential coefficient adjusted by the PID algorithm.

[0034] In one embodiment, the method for obtaining the optimal compressor frequency is: using the cooling rate error of all temperature difference values ​​under the parameter vector corresponding to the initial value as the input of the PID algorithm after adjusting the parameters, and outputting the optimal compressor frequency of the compressor in the chemical reactor.

[0035] In a second aspect, an embodiment of the present application also provides an automatic temperature control system for an antioxidant chemical reactor, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned methods for automatic temperature control of an antioxidant chemical reactor are implemented.

[0036] This application has at least the following beneficial effects:

[0037] This application determines the interval abnormal value based on the distribution and distribution range of the cooling rate errors of all temperature difference values ​​in the temperature difference adjustment interval, as well as the distribution of the temperature data corresponding to the temperature difference value, and considers the influence of the crystallization heat released by the antioxidant on the cooling rate in different temperature difference adjustment intervals, thereby improving the discrimination of the abnormal degree analysis of the stable cooling rate of the PID algorithm in different temperature difference adjustment intervals;

[0038] Furthermore, based on the change trend and distribution characteristics of the interval abnormal values ​​of all temperature difference adjustment intervals, the fluctuation value of the cooling rate is determined, the influence of the specific heat capacity of the saturated solution on the cooling rate is considered, and the interval abnormal values ​​of all temperature difference adjustment intervals are weighted, which improves the accuracy of the PID algorithm under the current parameters in the analysis of the control excellence of the subsequent chemical reactor cooling rate, thereby improving the accuracy of the subsequent PID algorithm parameter selection;

[0039] Furthermore, the explosion position offset is calculated according to the cooling rate fluctuation value of the PID algorithm, and the parameter adjustment range is selected according to the control effect of the current PID algorithm parameters on the cooling rate; the PID algorithm parameters are adjusted using the fireworks algorithm to obtain the adjusted parameters of the PID algorithm, and the optimal compressor frequency is obtained through the PID algorithm to control the cooling water temperature of the chemical reactor, thereby improving the stability of the cooling rate in the chemical reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A flowchart of a method for automatically controlling the temperature of an antioxidant chemical reactor provided in one embodiment of the present application;

[0042] Figure 2 It is a schematic diagram of the process of determining the temperature difference adjustment range;

[0043] Figure 3 This is a schematic diagram of the division of the temperature difference adjustment interval;

[0044] Figure 4 Schematic diagram of the fitted straight line for interval outliers. DETAILED DESCRIPTION

[0045] In the description of the embodiments of the present application, words such as "exemplary", "or", "for example" and the like are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "or", "for example" and the like is intended to present related concepts in a concrete manner.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the present application. The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. It should be understood that, unless otherwise specified, " / " means or.

[0047] It should also be noted that the terms "first" and "second" in the present application are used to distinguish similar objects rather than to describe a specific order or sequence.

[0048] The following is a detailed description of a specific scheme of an automatic temperature control method and system for an antioxidant chemical reactor provided by the present application in conjunction with the accompanying drawings.

[0049] See also Figure 1 , which shows a flow chart of the steps of an automatic temperature control method of an antioxidant chemical reactor provided by an embodiment of the present application, the method comprising the following steps:

[0050] Step 1, obtaining the initial values ​​of the proportional coefficient, integral coefficient and differential coefficient of the PID algorithm to form a parameter vector; collecting temperature data of the antioxidant crystallization at a preset first number of collection moments.

[0051] The attenuation curve method is used to obtain the initial values ​​of the proportional coefficient, integral coefficient and differential coefficient of the PID algorithm, and the initial values ​​of the proportional coefficient, integral coefficient and differential coefficient are combined into a parameter vector of the PID algorithm. Among them, the attenuation curve method is a well-known technology and will not be repeated in this application.

[0052] The temperature data of antioxidant crystallization is collected by a thermal resistance sensor installed in a chemical reactor, wherein the time interval for collecting temperature data by the thermal resistance sensor is t minutes, and the first M temperature data adjacent to the current time are arranged in time sequence to form a temperature sequence.

[0053] In this embodiment, the values ​​of t and M are 5 and 20 respectively. The values ​​of t and M are preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0054] Step 2: record the difference between each temperature data and its adjacent temperature data as a temperature difference value, and divide the temperature difference values ​​of all temperature data into multiple temperature difference adjustment intervals based on the change in the difference between the temperature difference values ​​of all temperature data and the preset ideal temperature difference value.

[0055] During the crystallization process of the antioxidant, the unstable cooling rate leads to insufficient separation of some impurities from the antioxidant, and different cooling rates lead to different crystal nucleus growth rates, resulting in mixed crystal forms of the antioxidant. Maintaining a stable cooling rate in the chemical reactor is a key condition to ensure that the antioxidant is fully separated from the impurities and obtain a single crystal antioxidant.

[0056] In the temperature sequence, the absolute value of the difference between each temperature data and its adjacent previous temperature data is used as the temperature difference value of each temperature data, wherein the temperature difference value of the first temperature data collected is set to 1. The temperature difference values ​​of all temperature data are arranged in time sequence to form a temperature difference sequence, which represents the change rate of the crystallization temperature of the antioxidant in the chemical reactor.

[0057] The absolute value of the difference between each temperature difference value and the preset ideal temperature difference value is used as the cooling rate error of each temperature difference value, which represents the deviation between the actual cooling rate of the antioxidant in the chemical reactor and its ideal cooling rate. Among them, the value of the preset ideal temperature difference value needs to be determined according to the type of antioxidant and the required crystallization effect.

[0058] The solubility of antioxidants at different temperatures is different, which causes the concentration of antioxidants in saturated solutions to change, causing the specific heat capacity of the solution to change. On the one hand, at the same cooling rate at different temperatures, the mass of antioxidants precipitated per unit time is different, resulting in different crystallization heat release and different changes in solution temperature; on the other hand, the different specific heat capacities of the solutions in the chemical reactor lead to different changes in solution temperature due to the same crystallization heat release. Therefore, when the PID algorithm is used to control the cooling rate of the chemical reactor, the crystallization heat released by the antioxidant and the change in the specific heat capacity of the saturated solution cause the cooling rate to fluctuate.

[0059] Considering the different fluctuations of the temperature difference values ​​at different temperatures in the temperature difference sequence, the temperature difference value with a cooling rate error of 0 is taken as the interval endpoint, and the temperature difference sequence is divided into various temperature difference adjustment intervals, where each temperature difference adjustment interval does not contain the interval endpoint. The flow chart of determining the temperature difference adjustment interval is as follows: Figure 2 The schematic diagram of the temperature difference adjustment interval is shown in Figure 3 As shown in the figure, the horizontal axis is the temperature difference element sequence, indicating the subscript of the temperature difference value in the temperature difference sequence, and the vertical axis is the cooling rate error. Each type of line corresponds to a temperature difference adjustment interval.

[0060] Step 3: Determine the interval abnormal value of each temperature difference adjustment interval based on the distribution of the differences between all temperature difference values ​​in each temperature difference adjustment interval and the preset ideal temperature difference value, the distribution range, and the distribution of the temperature data corresponding to the temperature difference value.

[0061] Based on the distribution and range of the cooling rate errors of all temperature difference values ​​in each temperature difference adjustment interval, combined with the distribution of the temperature data corresponding to all temperature difference values, the interval abnormal value of each temperature difference adjustment interval is determined, and the expression is:

[0062] ; In the formula, Indicates the interval abnormal value of the i-th temperature difference adjustment interval, reflecting the abnormal degree of the stable cooling rate of the PID algorithm within the temperature difference adjustment interval; Represents the number of temperature difference values ​​in the i-th temperature difference adjustment interval; represents the cooling rate error of the jth temperature difference value in the i-th temperature difference adjustment interval; It represents the maximum value of the cooling rate error of all temperature difference values ​​in the i-th temperature difference adjustment interval; It represents the average value of the normalized values ​​of the temperature data corresponding to all temperature difference values ​​in the i-th temperature difference adjustment interval.

[0063] It should be noted that the solubility of antioxidants changes greatly at higher temperatures, the precipitation rate in saturated solutions is greater, and the crystallization heat released by antioxidants in the same time is greater; therefore, due to the influence of crystallization heat, even if the temperature difference adjustment interval has the same cooling rate error, the actual temperature change of the temperature difference adjustment interval with a larger average value of temperature data may be greater.

[0064] The PID algorithm has a better control effect on the temperature in the chemical reactor in the temperature difference adjustment range with a larger average value of the temperature data, and the calculated interval abnormal value is smaller;

[0065] In addition, the number of temperature difference values ​​in the temperature difference adjustment interval represents the interval length. The longer the interval length is, the longer the transition time required for the PID algorithm to stabilize the cooling rate is, and the larger the sum of the cooling rate errors of the temperature difference values ​​in the temperature difference adjustment interval is, the greater the fluctuation of the overall temperature difference value in the interval is, the worse the effect of temperature control is, and the larger the interval abnormal value is; at the same time, the larger the maximum value of the cooling rate error in the temperature difference adjustment interval is, the larger the overshoot caused by the PID algorithm when stabilizing the cooling rate is, the greater the abnormality of controlling the cooling rate in the temperature difference adjustment interval is, and the larger the calculated interval abnormal value is.

[0066] Step 4: Determine the cooling rate fluctuation value of the PID algorithm based on the change trend and distribution characteristics of the interval abnormal value.

[0067] Get the fitted straight line of interval anomaly values ​​of all temperature difference adjustment intervals of the temperature difference sequence. The schematic diagram of the fitted straight line of interval anomaly values ​​is as follows: Figure 4 As shown, the horizontal axis in the figure is the order of interval anomaly elements, indicating the sequence number of the temperature difference adjustment interval corresponding to the interval anomaly value, and the vertical axis is the interval anomaly value. The straight line in the figure is the fitting straight line of the interval anomaly values ​​of all temperature difference adjustment intervals.

[0068] In this embodiment, the least squares straight line fitting method is used to obtain the fitting straight line. As other implementation methods, on the basis of obtaining the fitting straight line of the interval outlier value, the implementer can use other existing technologies to obtain the fitting straight line, such as linear regression analysis, weighted least squares method, etc., and this application does not make any special restrictions.

[0069] Based on the distribution characteristics of the interval abnormal values ​​of all temperature difference adjustment intervals and the slope of the fitting straight line, the cooling rate fluctuation value of the PID algorithm is determined, and the expression is:

[0070] ; In the formula, flu represents the cooling rate fluctuation value of the PID algorithm; exp() represents an exponential function with a natural constant as the base; k represents the slope of the fitting line; r represents the number of temperature difference adjustment intervals; It represents the interval abnormal value of the i-th temperature difference adjustment interval; i represents the serial number of the temperature difference adjustment interval; β represents a value preset to be greater than 0, the purpose of which is to use the β-power of the serial number of the temperature difference adjustment interval as a weight to improve the contribution of the later temperature difference adjustment interval to the adjustment of the PID algorithm parameters.

[0071] In this embodiment, the value of β is 0.5. The value of β is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0072] It should be noted that the interval abnormal value of the temperature difference adjustment interval reflects the abnormal degree of the cooling rate controlled by the PID algorithm. The larger the interval abnormal value of the temperature difference adjustment interval of the temperature difference sequence, the larger the fluctuation value of the cooling rate. The cooling rate in the reactor is controlled by the PID algorithm. The continuously decreasing cooling rate error makes the interval abnormal value gradually decrease. The slope of the fitting straight line is negative, and the smaller the slope, the faster the interval abnormal value decreases, the faster the cooling rate tends to stabilize, and the smaller the cooling rate fluctuation value.

[0073] As the temperature in the chemical reactor decreases, the solubility of the antioxidant gradually decreases, and the specific heat capacity of the saturated solution in the chemical reactor changes, resulting in differences in the degree of temperature fluctuation at different times, causing the transition time and overshoot of the PID algorithm with the same parameters to increase when stabilizing the cooling rate, resulting in a weakened control ability of the PID algorithm over the cooling rate, and a trend of decreasing abnormal values ​​in the interval at the end of the temperature difference sequence will weaken, and may even show an increasing trend; therefore, the greater the slope of the fitting straight line, the weaker the control ability of the PID algorithm over the cooling rate, and the exponential function is used to process the slope of the fitting straight line so that the cooling rate fluctuation value becomes larger when the slope of the fitting straight line is larger;

[0074] In addition, the more temperature difference adjustment intervals there are in the temperature difference sequence, the greater the fluctuation of the cooling rate, and the greater the cooling rate fluctuation value. When the serial number of the temperature difference adjustment interval is larger, the closer it is to the current temperature measurement moment, the more it can reflect the excellent control of the subsequent cooling rate by the PID algorithm under the current parameters, and its interval abnormal value has a greater reference value for the subsequent selection of PID algorithm parameters. Therefore, a higher weight is given to the interval abnormal value of the temperature difference adjustment interval that is closer to the current moment.

[0075] Step 5, based on the cumulative value of the difference between the temperature difference value of the temperature data under each parameter vector and the preset ideal temperature difference value, obtain the fitness value of each parameter vector in the parameter vector set in the fireworks algorithm; obtain the explosion radius of each parameter vector in the parameter vector set in the fireworks algorithm according to the fitness value, and determine the explosion position offset of each parameter vector in the parameter vector set based on the cooling rate fluctuation value and the explosion radius.

[0076] In the process of controlling the cooling rate, the change of temperature data can show the fluctuation trend of the temperature of the chemical reactor caused by the heat released by the crystallization of the antioxidant, and then reflect the influence of the change of the solubility of the antioxidant and the specific heat capacity of the solution on the cooling rate controlled by the PID algorithm under the current parameters. Since the traditional PID algorithm does not consider the change of the heat released by the crystallization of the antioxidant and the change of the specific heat capacity of the solution, the PID algorithm still uses the same parameters as before to control the cooling rate of the chemical reactor after the temperature drops, resulting in a poor effect of stabilizing the cooling rate in the chemical reactor.

[0077] When the fluctuation value of the cooling rate is small, the crystallization heat of the antioxidant changes slightly. Since the solubility of the antioxidant changes continuously with temperature, the cooling rate in the subsequent chemical reactor is less affected, and a small adjustment of the parameter vector of the PID algorithm can meet the purpose of stabilizing the cooling rate.

[0078] When the cooling rate fluctuates greatly, the temperature of the chemical reactor is greatly affected by the crystallization heat of the antioxidant and the change in the specific heat capacity of the saturated solution. The PID algorithm under the current parameters has a poor effect on stabilizing the cooling rate, and the parameters of the PID algorithm need to be adjusted over a large range. Therefore, the fireworks algorithm is used to adjust the PID algorithm parameters.

[0079] In order to avoid too large an adjustment range of the PID algorithm parameters, a parameter vector set is obtained according to the current parameters of the PID algorithm. The specific process is as follows:

[0080] (1) Taking each component of the current parameter vector of the PID algorithm as the center, construct a parameter interval of length U;

[0081] (2) Randomly select a positive number from each parameter interval to form a new parameter vector;

[0082] (3) Repeat step (2) until a total of N-1 new parameter vectors are formed, and then end the loop;

[0083] (4) The N-1 new parameter vectors and the current parameter vector of the PID algorithm are combined into a parameter vector set.

[0084] In this embodiment, the values ​​of U and N are 5 and 30 respectively. The values ​​of U and N are preset manually and can be set by the implementer. This application does not impose any special restrictions. For example, the first component of the parameter vector of the current PID algorithm is When , the parameter interval constructed with the first component as the center is [-2,3].

[0085] The control error of each parameter vector in the parameter vector set is used as the fitness value of each parameter vector in the parameter vector set, wherein the calculation process of the control error is: taking any parameter vector as an example, the transfer function of the temperature model of the chemical reactor control system is obtained by the step response method, and each component of the any parameter vector is used as the proportional coefficient, integral coefficient and differential coefficient of the PID algorithm respectively, and the temperature sequence is obtained by simulating the transfer function, which is recorded as the simulated temperature sequence, and the sum of the cooling rate errors of all temperature difference values ​​in the temperature difference sequence of the simulated temperature sequence is used as the control error of the any parameter vector. Among them, the step response method to obtain the transfer function of the temperature model of the chemical reactor control system is a well-known technology, and this application will not repeat it.

[0086] The explosion radius of each parameter vector in the parameter vector set in the fireworks algorithm is calculated according to the fitness value, wherein the calculation of the explosion radius in the fireworks algorithm is a well-known technology and will not be described in detail in this application.

[0087] Combining the cooling rate fluctuation value of the PID algorithm and the explosion radius of each parameter vector in the parameter vector set, the explosion position offset of each parameter vector in the parameter vector set is determined, and the expression is:

[0088] ; In the formula, Indicates the explosion position offset of the nth parameter vector in the parameter vector set, reflecting the adjustment range of each component in the nth parameter vector; It represents the explosion radius of the nth parameter vector in the fireworks algorithm in the parameter vector set; flu represents the cooling rate fluctuation value of the PID algorithm; rand() represents a random function that obeys a uniform distribution.

[0089] It should be noted that the greater the fluctuation value of the cooling rate of the PID algorithm, the greater the offset of the explosion position randomly generated in the fireworks algorithm, the wider the distribution range of the generated new parameter vector, the larger the optimization range of the parameter vector, and the larger the adjustment range of the parameters of the PID algorithm.

[0090] Step 6, based on the parameter vector set and the explosion position offset, use the fireworks algorithm to obtain the proportional coefficient, integral coefficient and differential coefficient adjusted by the PID algorithm, obtain the optimal compressor frequency of the compressor in the chemical reactor, and control the temperature of the chemical reactor.

[0091] The parameter vector set is used as the input of the fireworks algorithm, each new parameter vector is generated based on the explosion position offset, the maximum number of iterations is set to T, and each component of the parameter vector output by the fireworks algorithm is used as the proportional coefficient, integral coefficient and differential coefficient after adjustment of the PID algorithm.

[0092] In this embodiment, the value of T is 50. The value of T is preset manually and can be set by the implementer. This application does not impose any special restrictions.

[0093] The cooling rate error corresponding to all the temperature data in the temperature sequence obtained in step 1 is used as the input of the PID algorithm after adjusting the parameters, and the optimal compressor frequency of the compressor in the chemical reactor is output.

[0094] The optimal compressor frequency is used as the input of the frequency converter in the chemical reactor, and the compressor is controlled by the frequency converter to change the cooling water temperature of the chemical reactor and maintain the stability of the cooling rate during the crystallization of the antioxidant.

[0095] Based on the same inventive concept as the above method, an embodiment of the present application also provides an automatic temperature control system for an antioxidant chemical reactor, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of any one of the above-mentioned methods for automatic temperature control of an antioxidant chemical reactor when executing the computer program.

[0096] In summary, the present application determines the interval abnormal value based on the distribution and distribution range of the cooling rate errors of all temperature difference values ​​in the temperature difference adjustment interval, and the distribution of the temperature data corresponding to the temperature difference value, and considers the influence of the crystallization heat released by the antioxidant on the cooling rate in different temperature difference adjustment intervals, thereby improving the discrimination of the abnormal degree analysis of the stable cooling rate of the PID algorithm in different temperature difference adjustment intervals;

[0097] Furthermore, based on the change trend and distribution characteristics of the interval abnormal values ​​of all temperature difference adjustment intervals, the fluctuation value of the cooling rate is determined, the influence of the specific heat capacity of the saturated solution on the cooling rate is considered, and the interval abnormal values ​​of all temperature difference adjustment intervals are weighted, which improves the accuracy of the PID algorithm under the current parameters in the analysis of the control excellence of the subsequent chemical reactor cooling rate, thereby improving the accuracy of the subsequent PID algorithm parameter selection;

[0098] Furthermore, the explosion position offset is calculated according to the cooling rate fluctuation value of the PID algorithm, and the parameter adjustment range is selected according to the control effect of the current PID algorithm parameters on the cooling rate; the PID algorithm parameters are adjusted using the fireworks algorithm to obtain the adjusted parameters of the PID algorithm, and the optimal compressor frequency is obtained through the PID algorithm to control the cooling water temperature of the chemical reactor, thereby improving the stability of the cooling rate in the chemical reactor.

[0099] The flowchart and block diagram in the accompanying drawings show the possible architecture, function and operation of the system, method and computer program product according to the embodiment of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. In the description corresponding to the flowchart and the block diagram in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in a different order from the order disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified functions or actions, or may be implemented by a combination of dedicated hardware and computer instructions.

[0100] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the basic features of the present application. Therefore, no matter from which point of view, the above embodiments of the present application should be regarded as exemplary and non-restrictive.

Claims

1. An automatic temperature control method for an antioxidant chemical reactor, characterized in that: The method comprises the following steps: Obtaining initial values ​​of the proportional coefficient, integral coefficient, and differential coefficient of the PID algorithm to form a parameter vector, using the parameter vector as a reference, presetting multiple parameter vectors, and forming all parameter vectors into a parameter vector set; collecting temperature data of the antioxidant crystallization at a preset first number of collection moments; The difference between each temperature data and its adjacent temperature data is recorded as a temperature difference value, and based on the change in the difference between the temperature difference values ​​of all temperature data and the preset ideal temperature difference value, the temperature difference values ​​of all temperature data are divided into a plurality of temperature difference adjustment intervals; Determine the interval abnormal value of each temperature difference adjustment interval by combining the distribution of the differences between all temperature difference values ​​in each temperature difference adjustment interval and the preset ideal temperature difference value and the distribution of the temperature data corresponding to the temperature difference value; Determine the cooling rate fluctuation value of the PID algorithm based on the change trend and distribution characteristics of the abnormal values ​​in the interval; Based on the accumulated value of the difference between the temperature difference value of the temperature data under each parameter vector and the preset ideal temperature difference value, the fitness value of each parameter vector in the parameter vector set in the fireworks algorithm is obtained; according to the fitness value, the explosion radius of each parameter vector in the parameter vector set in the fireworks algorithm is obtained, and based on the cooling rate fluctuation value and the explosion radius, the explosion position offset of each parameter vector in the parameter vector set is determined; Based on the parameter vector set and the explosion position offset, a fireworks algorithm is used to obtain a proportional coefficient, an integral coefficient, and a differential coefficient adjusted by a PID algorithm, an optimal compressor frequency of a compressor in a chemical reactor is obtained, and a temperature of the chemical reactor is controlled; The process of determining the temperature difference adjustment interval is as follows: The absolute value of the difference between each temperature difference value and the preset ideal temperature difference value is used as the cooling rate error of each temperature difference value; All cooling rate errors are arranged in time sequence, the temperature difference value where the cooling rate error is 0 is taken as the interval endpoint, and all temperature difference values ​​are divided into various temperature difference adjustment intervals.

2. The automatic temperature control method of an antioxidant chemical reaction kettle according to claim 1, characterized in that: The process of obtaining the parameter vector set is as follows: (1) Taking each component of the current parameter vector of the PID algorithm as the center, a parameter interval of a preset length is constructed; (2) Randomly select a positive number from each parameter interval to form a new parameter vector; (3) Repeat step (2) until a preset second number of new parameter vectors are formed, and then end the loop; (4) Combining the preset second number of new parameter vectors and the current parameter vector of the PID algorithm into a parameter vector set.

3. The automatic temperature control method of an antioxidant chemical reaction kettle according to claim 1, characterized in that: The expression of the interval outlier value is: ; In the formula, represents the interval abnormal value of the i-th temperature difference adjustment interval; Represents the number of temperature difference values ​​in the i-th temperature difference adjustment interval; represents the cooling rate error of the jth temperature difference value in the i-th temperature difference adjustment interval; It represents the maximum value of the cooling rate error of all temperature difference values ​​in the i-th temperature difference adjustment interval; It represents the average value of the normalized values ​​of the temperature data corresponding to all temperature difference values ​​in the i-th temperature difference adjustment interval.

4. The automatic temperature control method of an antioxidant chemical reactor according to claim 1, characterized in that: The process of determining the cooling rate fluctuation value is as follows: Obtain the fitting straight line of the interval outliers of all temperature difference adjustment intervals; The expression of the cooling rate fluctuation value flu of the PID algorithm is: ; Wherein, exp() represents an exponential function with a natural constant as the base; k represents the slope of the fitting line; r represents the number of temperature difference adjustment intervals; represents the interval abnormal value of the i-th temperature difference adjustment interval; i represents the sequence number of the temperature difference adjustment interval; β represents a preset value greater than 0.

5. The automatic temperature control method of an antioxidant chemical reactor according to claim 1, characterized in that: The determination process of the fitness value is: The transfer function of the temperature model of the chemical reactor control system is obtained by the step response method; Using each component of any parameter vector as a proportional coefficient, an integral coefficient and a differential coefficient of a PID algorithm, and obtaining the preset first number of temperature data through the transfer function simulation; The sum of the cooling rate errors of the temperature difference values ​​of the preset first number of temperature data is used as the fitness value of any parameter vector.

6. The automatic temperature control method of an antioxidant chemical reactor according to claim 1, characterized in that: The expression of the explosion position offset is: ; In the formula, Represents the explosion position offset of the nth parameter vector in the parameter vector set; It represents the explosion radius of the nth parameter vector in the fireworks algorithm in the parameter vector set; flu represents the cooling rate fluctuation value of the PID algorithm; rand() represents a random function that obeys a uniform distribution.

7. The automatic temperature control method of an antioxidant chemical reactor according to claim 1, characterized in that: The method for obtaining the proportional coefficient, integral coefficient and differential coefficient after the PID algorithm is adjusted is: The parameter vector set is used as the input of the fireworks algorithm, and each new parameter vector is generated based on the explosion position offset. The components of the parameter vector output after the fireworks algorithm reaches a preset number of iterations are used as the proportional coefficient, integral coefficient and differential coefficient adjusted by the PID algorithm.

8. The automatic temperature control method of an antioxidant chemical reactor according to claim 1, characterized in that: The method for obtaining the optimal compressor frequency is: using the cooling rate errors of all temperature difference values ​​under the parameter vector corresponding to the initial value as the input of the PID algorithm after adjusting the parameters, and outputting the optimal compressor frequency of the compressor in the chemical reactor.

9. An automatic temperature control system for an antioxidant chemical reactor, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the automatic temperature control method for an antioxidant chemical reactor as described in any one of claims 1-8 are implemented.

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