A dcs control method and system applied to a coke inhibitor

Abstract

The application discloses a DCS control method and system applied to a coking inhibitor, which comprises an upper computer configuration module, a formula analysis module, a sequential interlocking module, a temperature and speed coupling module, a PID regulation module and a data recording module, the upper computer configuration module issues a target production formula, the formula analysis module decomposes a control parameter set, the sequential interlocking module controls material addition and stirring and heating, the temperature and speed coupling module acquires a reaction temperature and a water distributor water distribution rate, and determines a water distribution rate change trend factor according to a current water distribution rate and a historical water distribution rate sequence, the PID regulation module dynamically adjusts a target temperature set value by using the trend factor, and controls and adjusts a valve opening degree by using a PID algorithm, and the data recording module stores process data. The system improves the control adaptability of a coking inhibitor intermediate synthesis process through coupling of a water distribution rate change trend and a temperature control target.

Description

Technical Field

[0001] This invention relates to the field of chemical process control technology, specifically to a DCS control method and system applied to coking inhibitors. Background Technology

[0002] The production of coking inhibitors involves intermediate synthesis steps such as aldehyde-phenol condensation. Water is continuously generated during the reaction and discharged through a water separator. The water separation rate is a key dynamic indicator characterizing the reaction progress and intensity. Existing DCS control systems typically use preset temperature curves or PID constant-value regulation based on a single temperature deviation to control the temperature during this intermediate synthesis stage, failing to incorporate the water separation rate and its evolution into the temperature control decision loop. When raw material activity fluctuates, heating medium pressure changes, or stirring effects deviate, the constant or time-dependent temperature setpoint cannot match the actual reaction kinetics requirements, easily causing local temperature-reaction rate mismatches. This leads to prolonged reaction time, uneven distribution of intermediate molecular weights, and increased byproducts, ultimately affecting the dispersibility and coking inhibitor efficacy of the final coking inhibitor product. Some improved control schemes attempt to correct the temperature setpoint based on the current water separation rate. However, due to factors such as liquid surface disturbances within the water separator and intermittent discharge, the instantaneous water separation rate often experiences significant jumps. Directly using this value as the adjustment basis causes high-frequency oscillations in the temperature target value, resulting in frequent valve actuation and decreased system stability. The true evolution trend of the water separation rate is implicit in the temporal structure of continuous monitoring data. The value of a single sampling point is insufficient for characterization; it is necessary to infer from historical trajectories and the latest changes. The synthesis of coking inhibitor intermediates is sensitive to temperature windows. Excessive temperature easily induces phenol oxidation and aldehyde self-polymerization, while excessively low temperature results in slow condensation and low conversion rates. Therefore, it is urgent to solve how to extract reliable trend measures from the water separation rate sequences routinely collected by DCS, and to use this trend to dynamically generate target values ​​for reaction temperatures, thereby achieving adaptive coordination between temperature and reaction process without additional hardware and analytical instruments. Summary of the Invention

[0003] This invention provides a DCS control method and system for coking inhibitors, aiming to solve the problem of temperature control targets being out of sync with the actual reaction process due to the failure to incorporate the water separation rate change trend during the synthesis stage of coking inhibitor intermediates. By constructing a temperature-rate coupling mechanism and a dynamic target temperature generation logic, the reaction temperature can be automatically adjusted according to the water separation process, thereby improving the precision of batch control and the consistency of intermediate quality.

[0004] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a DCS control method and system for coking inhibitors, the system comprising a host computer configuration module, a formula analysis module, a sequential interlocking module, a temperature-rate coupling module, a PID control module, and a data recording module. The host computer configuration module responds to user-input batch commands and issues corresponding target production formula data; the formula analysis module decomposes the target production formula data into a first set of control parameters for the intermediate synthesis stage and a second set of control parameters for the compounding stage, realizing automatic decomposition and phased management of the formula data. The sequential interlocking module, based on the first set of control parameters, controls the regulating valve to sequentially add T154 additive, benzaldehyde, and 2,6-phenol to the reactor, and starts stirring and heating after adding toluene, thereby ensuring the precise and orderly addition of multiple materials during the intermediate synthesis stage and avoiding sequence errors and metering deviations caused by manual operation.

[0005] During the heating reaction, the temperature-rate coupling module acquires the current reaction temperature in the reactor in real time and the current water separation rate of the water separator within a preset time interval. Based on the current water separation rate and the historical water separation rate sequence of the water separator, a water separation rate change trend factor is determined. The PID control module dynamically adjusts the target setpoint of the current reaction temperature according to the water separation rate change trend factor and uses a PID algorithm to control the opening of the regulating valve, maintaining the reaction temperature in the reactor at the target setpoint. This system incorporates the water separation rate and its change trend into the temperature control loop, enabling the target temperature to be dynamically corrected according to the reaction progress and water separation rate. This effectively improves the accuracy and response speed of temperature control during the intermediate synthesis stage, avoiding over- or under-reaction caused by fixed temperature control settings, and ensuring the consistency of intermediate quality. The data recording module collects and stores data on reactor temperature, water separation rate, regulating valve opening, and formula execution status, providing complete data support for batch traceability and process optimization.

[0006] As a technical solution of this invention, when determining the water distribution rate change trend factor, the historical water distribution rates of the water distributor at N consecutive sampling times before the current moment are extracted from the historical database of the DCS controller, and arranged in chronological order to obtain a historical water distribution rate sequence, where N is a positive integer greater than or equal to 3. In the historical water distribution rate sequence, the first difference between the last historical water distribution rate and the first historical water distribution rate is calculated, and the average of the second differences between two adjacent historical water distribution rates in the historical water distribution rate sequence is calculated. The first difference is divided by the absolute value of the average value to obtain a first ratio, and the third difference between the current water distribution rate and the last historical water distribution rate is divided by the last historical water distribution rate to obtain a second ratio. The product of the first ratio and the second ratio is used as the water distribution rate change trend factor. The trend factor obtained in this way reflects both the historical evolution trajectory of the water distribution rate and the transient change amplitude at the current moment, enabling more accurate capture of the dynamic trend of the water distribution rate and providing a reliable basis for real-time adjustment of the temperature target.

[0007] In a preferred embodiment of the present invention, when dynamically adjusting the target set value of the current reaction temperature, a reference reaction temperature within a first set of control parameters is obtained, and a preset standard water separation rate for the intermediate synthesis stage is also obtained. The standard water separation rate is divided by the current water separation rate to obtain a third ratio, and the product of the third ratio and the water separation rate change trend factor is used as a temperature adjustment coefficient. The temperature adjustment coefficient is multiplied by the reference reaction temperature to obtain a temperature offset, and the reference reaction temperature and the temperature offset are added together to obtain the target set value. This adjustment mechanism allows the target temperature to be appropriately increased or decreased when the actual water separation rate deviates from the standard water separation rate and exhibits accelerated change, so as to actively adapt to the reaction kinetic requirements, suppress abnormal fluctuations in the water separation rate, and maintain the reaction operating within the ideal operating range.

[0008] As a further improvement of the present invention, when the PID control module uses the PID algorithm to control the opening of the regulating valve, the DCS controller collects the real-time reaction temperature of the reactor at the current moment and calculates the temperature deviation between the real-time reaction temperature and the target set value; calculates the proportional control component of the PID algorithm based on the temperature deviation value, and obtains the historical temperature deviation value of the reactor at the previous moment, and calculates the integral control component based on the historical temperature deviation value; obtains the rate of change of the real-time reaction temperature at multiple consecutive sampling moments, calculates the derivative control component, and superimposes the proportional control component, integral control component, and derivative control component to obtain the valve opening control quantity; the DCS controller outputs a 4-20mA current signal to the regulating valve according to the valve opening control quantity to adjust the opening of the regulating valve. After the adjustment is executed, the DCS controller also obtains the actual opening value of the regulating valve and calculates the opening deviation between the actual opening value and the target opening value. When the opening deviation is greater than the preset opening deviation threshold, a valve deviation alarm signal is sent to the host computer, and the real-time reaction temperature, target set value, valve opening control quantity and actual opening value at the current moment are recorded and stored as a valve deviation event log. This realizes closed-loop verification and fault early warning of the valve execution status, and improves the safety and self-diagnosis capability of the system operation.

[0009] Preferably, the proportional coefficient, integral time, and derivative time of the PID algorithm are set in segments according to different reaction process intervals in the intermediate synthesis stage, and the DCS controller automatically switches the corresponding PID parameter group according to the preset rate interval where the current water separation rate is located, so that the control parameters are matched with the dynamic characteristics of different reaction processes in real time, taking into account both the speed and stability of temperature control.

[0010] In a preferred embodiment of the present invention, when the formula analysis module decomposes the target production formula data, the DCS controller analyzes and obtains the first target mass of T154 additive, the second target mass of benzaldehyde, the third target mass of 2,6-phenol, and the fourth target mass of toluene required for the intermediate synthesis stage, and uses these target masses as the first set of control parameters; at the same time, it analyzes and obtains the fifth target mass of high-boiling-point aromatic solvent, the sixth target mass of coking inhibitor intermediate, and the seventh target mass of T203 additive required for the compounding stage, and uses them as the second set of control parameters, thereby realizing the structured decomposition of the formula and providing a directly usable set of parameters for precise staged feeding and control.

[0011] As another improvement of this invention, before controlling the feeding according to the first set of control parameters, the DCS controller obtains the empty reactor mass and calculates the total feeding mass based on the empty reactor mass and the target masses in the first set of control parameters; it sends a tare command to the weighing module at the bottom of the reactor, causing the weighing module to zero its current mass, and sends a feeding preparation signal to the host computer after the weighing module zeroes its mass. When controlling the feeding, the sequential interlocking module sequentially opens the first regulating valve connected to the T154 additive storage tank, the second regulating valve connected to the benzaldehyde storage tank, and the third regulating valve connected to the 2,6-phenol storage tank, and reads the mass value from the weighing module in real time. By comparing the accumulated mass with the target value, it gradually closes the corresponding regulating valves, achieving precise sequential feeding based on weight feedback. This fundamentally eliminates measurement errors caused by flow fluctuations or material adhering to the wall, ensuring strict adherence to the formula ratio.

[0012] The DCS control system applied to coking inhibitors also includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of the above-mentioned control method, integrating formula management, sequential feeding, temperature-rate coupling dynamic temperature regulation, and PID valve control into the same DCS platform. This achieves full automation and adaptive regulation of the coking inhibitor intermediate synthesis process, improving the product quality stability and production safety between batches.

[0013] The technical effects and advantages provided by the present invention in the above technical solution are as follows: Regarding the determination of the water distribution rate change trend factor, historical water distribution rates for N consecutive sampling times prior to the current moment are extracted from the historical database of the DCS controller. These rates are arranged chronologically to form a historical water distribution rate sequence. The first difference between the last historical water distribution rate and the first historical water distribution rate in this sequence is calculated. Simultaneously, the absolute average of the second differences between two adjacent historical water distribution rates within the sequence is calculated. Dividing the first difference by this average yields the first ratio, which characterizes the overall trend of the historical sequence and the relative intensity of local fluctuations. Then, the third difference between the current water distribution rate and the last historical water distribution rate is obtained, and this is divided by the last historical water distribution rate to obtain the second ratio, reflecting the instantaneous change magnitude compared to the most recent historical state. Multiplying the first ratio by the second ratio yields the water distribution rate change trend factor. This calculation method integrates the long-term development trend of the sequence with the current instantaneous change on a unified scale, weakening the false signals caused by occasional discharge pulses or liquid surface fluctuations of the water distributor, and accurately reflecting the kinetic stage migration of water released by the condensation reaction. The resulting trend factor possesses the ability to identify acceleration, stabilization, and decline processes in the reaction, providing a sensitive yet robust criterion for subsequent target temperature adjustments, avoiding misjudgments and over-adjustments caused by relying solely on fluctuations in the current value. Regarding the dynamic adjustment of the target temperature setpoint, the baseline reaction temperature and the preset standard water separation rate within the first control parameter set of the intermediate synthesis stage are obtained. The standard water separation rate is divided by the current water separation rate to obtain a third ratio, which indicates the deviation of the current reaction rate from the ideal state. The third ratio is multiplied by the water separation rate trend factor to obtain a temperature adjustment coefficient. This temperature adjustment coefficient is then multiplied by the baseline reaction temperature to obtain the temperature offset. Finally, the baseline reaction temperature and the temperature offset are added together to form the target setpoint. When water separation is on an upward trend and the current water separation rate is higher than the standard value, the trend factor is positive and the third ratio is less than 1. The combined effect of these two factors generates a positive temperature offset, moderately increasing the target temperature and promoting the forward condensation reaction. When the water separation rate shows a continuous decline, the trend factor turns negative, and the current water separation rate is lower than the standard value, the temperature adjustment coefficient generates a negative offset, automatically cooling down to suppress excessive reaction and by-product formation. The PID control module performs closed-loop regulation based on this target setpoint, calculating the proportional, integral, and derivative control components in real time and superimposing the output valve opening control quantity, thereby ensuring that the supply of heating medium continuously and smoothly adapts to the dynamic heat demand of the reaction process. This coupled control path makes the reaction temperature no longer a static number preset by the process engineer, but an adaptive variable linked to the internal process of the reaction. The condensation depth and heat input are balanced in real time, improving the regularity of the product molecular structure and the stability of batch yield, and also having a natural compensatory adaptability to small fluctuations in raw material quality. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0015] Figure 1 This is a block diagram of a DCS control system applied to coking inhibitors; Figure 2 This is a flowchart for calculating the target setpoints based on water separation rate and trend factor; Figure 3 This is a schematic diagram of the real-time value and historical sequence of water separation rate; Figure 4 It is the curve showing the target opening degree of the control valve, the actual opening degree, and the opening deviation. Figure 5 It is a curve showing the change in the target mass and total mass of the material during the feeding process in the reactor. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] See Figure 1This invention provides a DCS control system for coking inhibitors, including a host computer configuration module, a formula analysis module, a sequence interlocking module, a temperature-rate coupling module, a PID control module, and a data recording module. The host computer configuration module responds to user-input batch commands and issues corresponding target production formula data; the formula analysis module decomposes the target production formula data into the first set of control parameters for the intermediate synthesis stage and the second set of control parameters for the compounding stage; the sequential interlocking module controls the regulating valve to add T154 additive, benzaldehyde, and 2,6-phenol sequentially to the reactor according to the first set of control parameters, and starts stirring and heating after adding toluene; the temperature-rate coupling module acquires the current reaction temperature in the reactor in real time during heating and acquires the current water separation rate of the water separator within a preset time interval, and determines the water separation rate change trend factor based on the current water separation rate and the historical water separation rate sequence of the water separator; the PID control module dynamically adjusts the target set value of the current reaction temperature according to the water separation rate change trend factor, and uses a PID algorithm to control the opening of the regulating valve to maintain the reaction temperature in the reactor at the target set value; the data recording module collects and stores the reactor temperature, water separation rate, regulating valve opening, and formula execution status data.

[0018] In practical implementation, the historical water distribution rate of the water distributor is extracted from the historical database of the DCS controller for N consecutive sampling times prior to the current time. This historical water distribution rate sequence is obtained by arranging the data in chronological order, where N is a positive integer greater than or equal to 3. The historical database of the DCS controller stores the operating data of the water distributor at fixed time intervals, which are preset to 30 seconds during the coking agent intermediate synthesis stage. The specific value of N is input by the production operator on the human-machine interface of the DCS controller, set in the upper-level computer configuration module, and then sent to the DCS controller. The DCS controller extracts the corresponding number of historical water distribution rate data points from the historical database based on the received N value. For example, when N is 5, the historical water distribution rate values ​​corresponding to the 5 consecutive sampling times prior to the current time are extracted, arranged in chronological order to form the historical water distribution rate sequence, and marked as follows. .

[0019] After obtaining the historical water allocation rate sequence, calculate the first difference between the last historical water allocation rate and the first historical water allocation rate in the historical water allocation rate sequence. The first difference is... Simultaneously, calculate the average of the second differences between two adjacent historical water separation rates in the historical water separation rate sequence. The second difference between two adjacent historical water separation rates refers to the difference between any two consecutive values ​​in the sequence. The absolute value of the multiple second differences is then calculated, followed by the arithmetic mean, to obtain the absolute value of the mean. The formula is:

[0020] in, Factors indicating the trend of water separation rate change. This represents the last historical water separation rate in the historical water separation rate sequence. This represents the first historical water separation rate in the historical water separation rate sequence. Represents the first in the historical water separation rate sequence A historical water separation rate, From 1 to Positive integer index variable, This indicates the current water distribution rate of the water distributor within a preset time interval.

[0021] Specifically, the first ratio is obtained by dividing the first difference by the absolute value of the average value; the second ratio is obtained by dividing the third difference between the current water distribution rate and the last historical water distribution rate by the last historical water distribution rate; and the product of the first ratio and the second ratio is used as the water distribution rate change trend factor. All of the above calculations are performed using the preset operational logic in the temperature-rate coupling module of the DCS controller.

[0022] In other implementations, the value of N is determined based on the reaction duration and sampling interval of the intermediate synthesis stage. When the reaction duration is long and the water separation rate changes relatively gradually, N can be set to a larger value, such as 8 or 10, to reflect the evolution characteristics of the water separation rate over a longer time window; when the reaction is in a phase of rapid water separation rate change, N can be set to a smaller value, such as 3 or 4, to more sensitively capture recent trends in water separation rate changes. The DCS controller allows operators to modify the setting of N by authorization before the batch begins or during the reaction. The modification takes effect immediately and is applied to the calculation of the next water separation rate change trend factor.

[0023] The extraction of historical water distribution rate sequences is completed by the DCS controller's data recording module in conjunction with a historical database. The historical database employs a circular storage strategy, storing recently generated water distribution rate data in a high-speed cache to ensure that the response time for the extraction operation is less than 100 milliseconds, thus not delaying the real-time calculations of the subsequent PID control module. Each time the temperature-rate coupling module calculates the water distribution rate change trend factor, it reads the latest historical water distribution rate sequence from the historical database and combines it with the current water distribution rate to calculate the water distribution rate change trend factor in real time. This trend factor is then immediately transmitted to the PID control module for dynamic adjustment of the subsequent target setpoint.

[0024] See Figure 3 In the graph, the horizontal axis represents the sampling time number, and the vertical axis represents the water separation rate, in milliliters per minute. In the legend, the blue solid line curve represents the real-time value of the water separation rate, and the red hollow dots represent the historical water separation rate sequence. The solid green square represents the current water distribution rate. According to one embodiment above, the historical sequence of water distribution rates is formed by the DCS controller extracting water distribution rate data points from the historical database for the five consecutive sampling times preceding the current time, and arranging them in chronological order. It is used to calculate the trend factor of water separation rate change.

[0025] The solid blue line in the graph shows the trend of water separation rate with sampling time. Initially, the water separation rate gradually increases from approximately 0.8 mL / min to a peak of approximately 3.4 mL / min. Subsequently, the water separation rate begins to decrease, dropping to approximately 0.75 mL / min around sampling time 500. The red dots at the end of the graph correspond to the most recent 5 historical water separation rate data, with values ​​stabilizing at around 0.9 mL / min. The green square indicates the current water separation rate of 0.75 mL / min, meaning the current water separation rate is slightly lower than the last sampling point in the historical sequence. .

[0026] In specific implementation, please refer to Figure 2 The PID control module acquires the baseline reaction temperature from the first set of control parameters and the preset standard water separation rate for the intermediate synthesis stage. The first set of control parameters is obtained by the formula analysis module based on the target production formula data and stored in the DCS controller's memory. The baseline reaction temperature is the initial reaction temperature value expected to be maintained during the condensation reaction between the catalyst and the main material in the intermediate synthesis stage. Its specific value is determined by the process engineer based on the synthesis reaction characteristics of the coking inhibitor intermediate and is pre-written into the target production formula data. The standard water separation rate is the amount of water that the water separator should produce per unit time under ideal reaction conditions in the intermediate synthesis stage. The standard water separation rate is expressed as volumetric flow rate, and its value is also determined by the process engineer based on pilot-scale and intermediate-scale data and stored in the process parameter area of ​​the target production formula data.

[0027] The PID control module reads the reference reaction temperature from the DCS controller's memory, the standard water separation rate from the target production formula data, and obtains the current water separation rate and the water separation rate trend factor from the temperature-rate coupling module. The current water separation rate is the volumetric flow rate value actually collected and calculated by the water separator within a preset time interval, which is set to 60 seconds based on the characteristics of the reaction stage. The water separation rate trend factor is a dimensionless value calculated based on the historical water separation rate sequence and the current water separation rate. Its calculation process is completed by the temperature-rate coupling module and transmitted to the PID control module in real time. The value of the water separation rate trend factor can be positive, negative, or zero. A positive value indicates an upward trend in the water separation rate, a negative value indicates a downward trend, and zero indicates no trend change in the water separation rate.

[0028] The PID control module divides the standard water dispensing rate by the current water dispensing rate to obtain a third ratio. Before calculating the third ratio, the PID control module determines whether the current water dispensing rate is greater than a preset minimum water dispensing rate threshold. The preset minimum water dispensing rate threshold is set to 0.05 ml / min. When the current water dispensing rate is less than or equal to 0.05 ml / min, the third ratio is directly assigned a value of 1 to avoid division by zero or excessive temperature adjustment. When the current water dispensing rate is greater than 0.05 ml / min, the third ratio is calculated based on the actual quotient of the standard water dispensing rate and the current water dispensing rate.

[0029] The PID control module multiplies the third ratio by the water separation rate change trend factor, and the product is used as the temperature adjustment coefficient. The temperature adjustment coefficient is a dimensionless multiplier factor that characterizes the strength of the correction to the reference reaction temperature under the combined effect of the water separation rate change trend and the degree of deviation of the water separation rate from the standard.

[0030] The PID control module multiplies the temperature adjustment coefficient by the reference reaction temperature to obtain the temperature offset. The temperature offset is measured in degrees Celsius, and its absolute value is influenced by both the temperature adjustment coefficient and the reference reaction temperature. The PID control module then adds the reference reaction temperature to the temperature offset to obtain the target setpoint. The formula for calculating the target setpoint is:

[0031] in, This represents the target set value, in degrees Celsius. Indicates the reference reaction temperature, in degrees Celsius; This indicates the standard water separation rate, measured in milliliters per minute. This indicates the current water separation rate, expressed in milliliters per minute. The factor representing the trend of water separation rate is a dimensionless value.

[0032] In other implementations, after obtaining the target setpoint, the PID control module compares it with preset upper and lower temperature limits. The preset upper and lower temperature limits are determined by process safety regulations; for example, the upper temperature limit for the intermediate synthesis stage is 135 degrees Celsius, and the lower temperature limit is 100 degrees Celsius. When the calculated target setpoint is higher than the upper temperature limit, it is forcibly set to the upper temperature limit; when the calculated target setpoint is lower than the lower temperature limit, it is forcibly set to the lower temperature limit. This limiting process ensures that the reaction temperature always operates within the process safety boundaries.

[0033] In other implementations, the PID control module smooths the temperature offset when the reference reaction temperature is updated. The rate of change of the temperature offset is limited, meaning the absolute value of the difference between the temperature offsets in two adjacent calculation cycles does not exceed a preset offset change limit. This offset change limit is set at 2 degrees Celsius per cycle. When the absolute value of the difference between the newly calculated temperature offset and the temperature offset of the previous cycle is greater than 2 degrees Celsius, the temperature offset is only increased or decreased by 2 degrees Celsius based on the previous cycle. This smoothing process avoids drastic fluctuations in the target setpoint from impacting the PID control loop.

[0034] After obtaining the target setpoint after amplitude limiting and smoothing, the PID control module uses the target setpoint as the input target value of the PID algorithm to perform closed-loop control of the reaction temperature in the reactor.

[0035] In practice, the DCS controller acquires the real-time reaction temperature of the reactor using a platinum resistance thermometer installed on the inner wall of the reactor. The temperature signal is converted into a digital signal by the analog input module and stored in the DCS controller's memory. The DCS controller subtracts the real-time reaction temperature from the target setpoint provided by the PID control module to obtain the temperature deviation value. The temperature deviation value is denoted as... The value is the difference between the target setpoint and the real-time reaction temperature, expressed in degrees Celsius.

[0036] When calculating the proportional control component of the PID algorithm based on the temperature deviation value, the DCS controller will use the temperature deviation value... The ratio of the preset ratio Multiply them, and the product is the proportional control component. Proportional coefficient. The gain coefficient is a dimensionless coefficient, and its specific value is determined by the PID parameter set. The selection method of the PID parameter set will be explained in subsequent paragraphs.

[0037] When retrieving the historical temperature deviation value of the reactor at the previous moment, the DCS controller reads the temperature deviation value stored in the previous PID calculation cycle from its deviation history buffer in memory. This value is marked as... The integral control component is calculated based on the accumulation of historical temperature deviation values: In each PID operation cycle, the DCS controller calculates the current temperature deviation value... The integral is accumulated over time. The accumulated deviation value stored in the integral accumulator is denoted as... Update is performed in each computation cycle. ,in The sampling time interval for PID calculation is 0.5 seconds. The integral control component consists of the integral coefficient. With the value of the integral accumulator Multiply them to get the result.

[0038] When acquiring the rate of change of the real-time reaction temperature over multiple consecutive sampling times, the DCS controller reads the sampled value of the real-time reaction temperature at the current moment. and the sampled value at the previous sampling time. Calculate the difference between the two and divide by the sampling time interval. The rate of change of the real-time reaction temperature is obtained. This rate of change is related to the differential coefficient. Multiplying yields the differential control component. Differential coefficients. The unit of measurement is seconds, and its value is also determined by the PID parameter set.

[0039] The valve opening control quantity is obtained by superimposing the proportional control component, integral control component, and derivative control component. The formula for calculating the valve opening control quantity is:

[0040] in, This indicates the valve opening control amount, expressed as a percentage, with a value ranging from 0% to 100%. This is the proportionality coefficient; This represents the temperature deviation value at the current moment. The integral coefficient is expressed in units of 1000 ppm. ; This is the value of the integrator accumulator, obtained by accumulating historical temperature deviation values, in units of... ; These are the differential coefficients, in units of... ; The real-time reaction temperature at the current moment; This represents the real-time reaction temperature at the previous sampling time. This represents the sampling time interval.

[0041] The DCS controller controls the quantity based on the valve opening. A 4-20mA current signal is output to the regulating valve via a digital-to-analog converter module to adjust the valve's opening. The specific mapping relationship is as follows: when... When it is 0%, the output current signal is 4mA; when When it is 100%, the output current signal is 20mA, and the intermediate values ​​are converted according to a linear relationship.

[0042] The proportional gain of the PID algorithm Integral coefficient and differential coefficients The DCS controller is segmented according to different reaction process intervals during the intermediate synthesis stage. Multiple PID parameter sets are stored in the DCS controller's memory. Each PID parameter set corresponds to a set of proportional, integral, and derivative coefficients. These PID parameter sets are pre-determined by process engineers based on reaction kinetics. The reaction process intervals are divided by the water separation rate. Specifically, the preset rate intervals are: the first rate interval is when the current water separation rate is greater than 1.5 ml / min; the second rate interval is when the current water separation rate is between 0.5 ml / min and 1.5 ml / min; and the third rate interval is when the current water separation rate is less than 0.5 ml / min. Before each PID calculation cycle, the DCS controller obtains the current water separation rate from the temperature-rate coupling module, determines the preset rate interval in which the current water separation rate falls, and automatically loads the PID parameter set corresponding to that preset rate interval, including the loaded proportional coefficients. Integral coefficient and differential coefficients Used for calculating control components in the current cycle. When the current water distribution rate crosses the boundary of the preset rate interval, the PID parameter group switches smoothly in the next PID calculation cycle, without causing a sudden change in the valve opening control quantity at the moment of switching.

[0043] In practical implementation, after the DCS controller outputs a 4-20mA current signal to the control valve, it obtains the actual opening value of the control valve at the current moment through a valve position feedback sensor installed on the control valve. The valve position feedback sensor is an angular stroke transmitter or a linear stroke transmitter, and its output signal is a 4-20mA analog current signal, corresponding to the fully closed to fully open position of the control valve. The analog input module of the DCS controller converts the 4-20mA current signal into a 1V to 5V voltage signal using a 250-ohm precision sampling resistor, and then converts it into a digital signal by an analog-to-digital converter. The DCS controller converts the digital signal into a percentage form of the actual opening value according to a linear mapping relationship. , The value ranges from 0.0% to 100.0%.

[0044] The DCS controller reads the target opening value corresponding to the valve opening control quantity from the memory image area of ​​the PID control module. , Also expressed as a percentage, with values ​​ranging from 0.0% to 100.0%. Valve opening control quantity. With the target opening value Numerically consistent, that is .

[0045] The DCS controller calculates the actual opening value. With the target opening value The opening deviation between them, the expression for the opening deviation is:

[0046] in, This indicates the opening deviation, expressed as a percentage. The actual opening degree of the control valve at the current moment, expressed as a percentage; This represents the target opening value corresponding to the valve opening control quantity, expressed as a percentage.

[0047] The DCS controller will calculate the opening deviation. The deviation is compared with a preset opening deviation threshold. The preset opening deviation threshold is set at 5.0%, a value determined based on the positioning accuracy level of the control valve and process control requirements. The intelligent positioner used in the control valve has a positioning accuracy of ±1.5%. Considering the potential mechanical backlash and frictional resistance during the actuator's movement, a 3.5% margin is allowed, and the preset opening deviation threshold is set to 5.0%. When the actual opening value deviates from the target opening value by more than 5.0%, it indicates an abnormal response of the control valve, which may be caused by insufficient air supply pressure, valve core jamming, or positioner malfunction.

[0048] In other embodiments, the preset opening deviation threshold can be configured differently according to different reaction process intervals. For example, in the initial stage of heating during the intermediate synthesis stage, the regulating valve operates frequently, and the preset opening deviation threshold can be widened to 8.0%; in the heat preservation reaction stage, the regulating valve operates less, and the preset opening deviation threshold can be narrowed to 3.0%. The DCS controller automatically switches the corresponding preset opening deviation threshold according to the current reaction process interval.

[0049] When the opening deviation When the valve deviation exceeds a preset opening deviation threshold, the DCS controller sends a valve deviation alarm signal to the host computer configuration module via Ethernet communication protocol. The valve deviation alarm signal is encapsulated in the form of a standard alarm data packet, which includes an alarm type identifier, the regulating valve position number, a timestamp indicating the alarm occurrence, and the opening deviation. The current value. After receiving the valve deviation alarm signal, the host computer configuration module displays the alarm information to the operator on the human-machine interface with a flashing red icon and sound prompts.

[0050] Simultaneously, the DCS controller records the real-time response temperature, target setpoint, valve opening control value, and actual opening value at the current moment, storing these as valve deviation event logs in the DCS controller's local memory. The local memory is the DCS controller's non-volatile flash memory storage area, managed using a circular storage file system. The valve deviation event log is stored in structured data record format, with each record containing the following fields: timestamp of the event (accurate to milliseconds), real-time response temperature (in degrees Celsius), target setpoint (in degrees Celsius), valve opening control value (in percentage), actual opening value (in percentage), and opening deviation. (Unit: percentage), preset opening deviation threshold (unit: percentage), and the current reaction process interval identifier. After each valve deviation event log is completed, the DCS controller immediately sends a log recording confirmation signal to the upper-level computer configuration module to ensure that the alarm signal and event log recording are completed synchronously.

[0051] See Figure 4 In the figure, the horizontal axis represents the sampling time number, ranging from 0 to 500, and the vertical axis represents the valve opening percentage, ranging from 0% to 70%. The figure contains four curves, namely the target opening value (blue dashed line), the actual opening value (red solid line), the opening deviation (orange solid line), and the preset opening deviation threshold (purple dashed line, fixed at 5.0%).

[0052] The target opening value curve fluctuates periodically, with the value mainly ranging from 20% to 70%, reflecting the trend of the valve opening control output of the PID control module dynamically adjusting over time. The actual opening value curve closely follows the target opening value, and the overall trend is consistent, indicating that the control valve responds promptly and can achieve the target opening control requirements well, but there are some deviations and fluctuations in local details.

[0053] The opening deviation curve exhibits multiple peaks, with the highest peak reaching approximately 20%, significantly exceeding the preset opening deviation threshold of 5.0% shown in the graph. This threshold is determined by a combination of process control requirements and valve positioning accuracy, serving as a boundary standard for judging whether the control valve's response is normal. The opening deviation remains below the threshold at most sampling times, indicating that the valve response is basically normal; however, in certain time periods, such as around sampling times 80 to 110, the opening deviation increases significantly and continues to exceed the threshold, suggesting that the control valve may exhibit abnormal response during this stage, such as valve core jamming or positioner malfunction.

[0054] The fluctuation of the opening deviation is closely related to the changes in the target opening value and the actual opening value. When the target opening changes rapidly, the actual opening value exhibits a response lag, leading to an increase in the opening deviation. This phenomenon is consistent with the description of the control valve position feedback detection and deviation alarm mechanism in the above embodiment. Although the peak value of the opening deviation in the figure occasionally exceeds the threshold, it does not continuously exceed the limit overall, indicating that the preset threshold is reasonable and the alarm mechanism can effectively capture anomalies.

[0055] In practice, the DCS controller parses the target production formula data. This data is generated by the host computer configuration module in response to batch commands and stored in the DCS controller's memory formula buffer in a structured data frame format. The target production formula data includes a formula identifier, formula version number, and bill of materials (BOM) for the intermediate synthesis stage and the compounding stage. Following a predefined formula parsing template, the DCS controller reads the material code, material name, and target mass value from each item in the BOM to obtain the first target mass of the T154 additive required for the intermediate synthesis stage. The second target mass of benzaldehyde The third target mass of 2,6-phenol and the fourth target mass of toluene ,Will , , and The parameters are combined into a first set of control parameters and stored in the control parameter data structure of the DCS controller. The DCS controller then continues to parse the bill of materials for the compounding stage to obtain the fifth target mass of the high-boiling-point aromatic solvent required for the compounding stage. The sixth target quality of coking inhibitor intermediates The seventh target quality of T203 additive ,Will , and Combine them into a second set of control parameters and store them.

[0056] Before adding T154 additive, benzaldehyde, and 2,6-phenol sequentially to the reactor according to the first set of control parameters, the DCS controller obtains the empty reactor mass. The empty reactor mass is pre-calibrated and stored in the reactor's static parameter table. The DCS controller reads the empty reactor mass using the reactor tag number index. The DCS controller is based on the empty reactor mass. and the first target mass within the first set of control parameters Second target quality Third target quality and the fourth objective quality Calculate the total mass of materials fed. The calculation formula is:

[0057] in, This indicates the total mass of the reactor after feeding is completed, in kilograms. This indicates the mass of the reactor when it is empty, expressed in kilograms. This indicates the first target mass of additive T154, in kilograms. The second target mass of benzaldehyde is expressed in kilograms. The third target mass of 2,6-phenol is expressed in kilograms. This represents the fourth target mass of toluene, in kilograms. The DCS controller will calculate the... Stored in memory for total quantity verification after feeding is completed.

[0058] The DCS controller sends a tare command to the weighing module at the bottom of the reactor via a fieldbus, writing the tare command code to the weighing module's register. Upon receiving the tare command, the weighing module sets its current measured mass value to zero, completing the tare operation. After tare completion, the weighing module returns a ready status word through its status register. The DCS controller polls and reads the status register; once it confirms that the weighing module has successfully returned to zero, it sends a feeding preparation ready signal to the host computer configuration module. The host computer configuration module then illuminates the feeding preparation ready indicator light on its human-machine interface.

[0059] The process of the DCS controller controlling the regulating valve to sequentially add T154 additive, benzaldehyde, and 2,6-phenol to the reactor is as follows: The DCS controller opens the first regulating valve connected to the T154 additive storage tank. The opening of the first regulating valve is achieved by writing a 20mA current signal to the analog output channel of the first regulating valve, resulting in a fully open first regulating valve. The DCS controller reads the first current mass value from the weighing module in real time. This first current mass value is acquired through the analog input channel of the weighing module at a sampling rate of 10 times per second. When the first current mass value reaches the first target mass... At this time, the DCS controller outputs a 4mA current signal to the first regulating valve to close the first regulating valve.

[0060] After confirming that the first regulating valve is closed, the DCS controller opens the second regulating valve connected to the benzaldehyde storage tank, and the second regulating valve is fully open. The DCS controller reads the second current mass value from the weighing module in real time, and when the second current mass value reaches the second target mass... With the first target quality When the sum of the values ​​is reached, the second regulating valve is closed.

[0061] After confirming that the second regulating valve is closed, the DCS controller opens the third regulating valve connected to the 2,6-phenol storage tank, and the third regulating valve is fully open. The DCS controller reads the third current mass value from the weighing module in real time, and when the third current mass value reaches the third target mass... Second target quality and the first target quality When the sum of the values ​​is reached, the third regulating valve is closed. During the feeding process, the DCS controller continuously records the on / off status of each regulating valve and the current mass value of the weighing module. The feeding data is stored by the data recording module as part of the formula execution status data.

[0062] The proportional gain, integral time, and derivative time of the PID algorithm are segmented according to different reaction process intervals in the intermediate synthesis stage. The reaction process intervals are divided into multiple preset rate intervals based on the water separation rate: a first preset rate interval, a second preset rate interval, and a third preset rate interval. The first preset rate interval corresponds to a water separation rate greater than 1.5 ml / min, the second preset rate interval corresponds to a water separation rate between 0.5 ml / min and 1.5 ml / min, and the third preset rate interval corresponds to a water separation rate less than 0.5 ml / min. Each preset rate interval corresponds to a set of PID parameters, which includes the proportional gain. Integral Time and differential time The DCS controller obtains the current water distribution rate through the temperature-rate coupling module, determines the preset rate range in which the current water distribution rate falls, and automatically loads the proportional coefficient corresponding to that preset rate range from the PID parameter group storage area. Integral Time and differential time This allows the PID control module to use the newly loaded PID parameter set for control component calculation in the next calculation cycle. When the current water distribution rate crosses the boundary of the preset rate interval, the PID parameter set switches in a non-disruptive switching mode, and the changes in the proportional coefficient, integral time, and derivative time do not affect the continuity of the valve opening control quantity.

[0063] See Figure 5 In the graph, the horizontal axis represents time in seconds, and the vertical axis represents mass in kilograms. The solid blue line represents the trend of the total mass of the reactor over time, while the dashed orange, green, red, and purple lines represent the target mass levels of additive T154, benzaldehyde, 2,6-phenol, and toluene, respectively.

[0064] As shown in the figure, the total mass of the reactor starts from approximately 500 kg and increases linearly over time, gradually approaching the cumulative sum of the target masses of each component. Specifically, the total mass of the reactor reaches the target mass of T154 additive, 530 kg, at approximately 200 seconds, indicating that the feeding process of T154 additive is complete. Subsequently, the total mass continues to rise, reaching the sum of the target masses of benzaldehyde and T154 additive, 550 kg, at approximately 350 seconds, marking the completion of benzaldehyde feeding. Then, the total mass further increases, reaching the sum of the target masses of 2,6-phenol, benzaldehyde, and T154 additive, 590 kg, at approximately 650 seconds, indicating the completion of 2,6-phenol feeding.

[0065] When the total mass of the reactor approaches the target mass of toluene (640 kg), the curve stabilizes, indicating that all target materials have been sequentially fed and the total mass of materials in the reactor has reached the preset total mass after feeding. This stabilization phase begins approximately 900 seconds, with the total mass of the reactor fluctuating around 640 kg, consistent with the total feeding mass defined in the above embodiment. Calculation and verification requirements.

[0066] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A DCS control method applied to coking inhibitors, characterized in that, The method includes: The host computer configuration module is used to respond to batch commands input by the user and send out the corresponding target production formula data; The formula analysis module is used to decompose the first set of control parameters for the intermediate synthesis stage and the second set of control parameters for the compounding stage based on the target production formula data. The sequential interlocking module is used to control the regulating valve to add T154 additive, benzaldehyde and 2,6 phenol sequentially into the reactor according to the first set of control parameters, and to start stirring and heating after adding toluene; The temperature-rate coupling module is used to acquire the current reaction temperature in the reactor in real time during the heating process, and to acquire the current water separation rate of the water separator within a preset time interval. Based on the current water separation rate and the historical water separation rate sequence of the water separator, the water separation rate change trend factor is determined. The PID control module is used to dynamically adjust the target set value of the current reaction temperature according to the water separation rate change trend factor, and to use the PID algorithm to control the opening of the regulating valve so that the reaction temperature in the reactor is maintained at the target set value. The data recording module is used to collect and store data on the temperature, water separation rate, regulating valve opening, and formula execution status of the reactor.

2. The DCS control method for coking inhibitors according to claim 1, characterized in that, Based on the current water distribution rate and the historical water distribution rate sequence of the water distributor, a water distribution rate change trend factor is determined, including: Extract the historical water distribution rate of the water distributor for N consecutive sampling times before the current time from the historical database of the DCS controller, and arrange them in chronological order to obtain the historical water distribution rate sequence, where N is a positive integer greater than or equal to 3; In the historical water separation rate sequence, the first difference between the last historical water separation rate and the first historical water separation rate is calculated, and the average of the second differences between two adjacent historical water separation rates in the historical water separation rate sequence is calculated. Divide the first difference by the absolute value of the average value to obtain a first ratio, and divide the third difference between the current water distribution rate and the last historical water distribution rate by the last historical water distribution rate to obtain a second ratio. The product of the first ratio and the second ratio is used as the water distribution rate change trend factor.

3. The DCS control method for coking inhibitors according to claim 2, characterized in that, Based on the water separation rate change trend factor, the target setpoint for the current reaction temperature is dynamically adjusted, including: Obtain the reference reaction temperature within the first set of control parameters, and obtain the preset standard water separation rate for the intermediate synthesis stage; Divide the standard water separation rate by the current water separation rate to obtain a third ratio, and use the product of the third ratio and the water separation rate change trend factor as the temperature adjustment coefficient. Multiply the temperature adjustment coefficient by the reference reaction temperature to obtain the temperature offset, and add the reference reaction temperature to the temperature offset to obtain the target set value.

4. The DCS control method for coking inhibitors according to claim 3, characterized in that, The step of using a PID algorithm to control the opening of the regulating valve to maintain the reaction temperature inside the reactor at the target set value includes: The DCS controller acquires the real-time reaction temperature of the reactor at the current moment and calculates the temperature deviation between the real-time reaction temperature and the target set value. Based on the temperature deviation value, the proportional control component of the PID algorithm is calculated, and the historical temperature deviation value of the reactor at the previous moment is obtained. Based on the historical temperature deviation value, the integral control component of the PID algorithm is calculated. The rate of change of the real-time reaction temperature at multiple consecutive sampling times is obtained, the derivative control component of the PID algorithm is calculated based on the rate of change, and the proportional control component, the integral control component and the derivative control component are superimposed to obtain the valve opening control quantity. The DCS controller outputs a 4-20mA current signal to the regulating valve according to the valve opening control amount, thereby adjusting the opening of the regulating valve.

5. The DCS control method for coking inhibitors according to claim 4, characterized in that, After the DCS controller outputs a 4-20mA current signal to the regulating valve according to the valve opening control amount, the following is also included: The DCS controller obtains the actual opening value of the regulating valve at the current moment, and calculates the opening deviation between the actual opening value and the target opening value corresponding to the valve opening control quantity; When the opening deviation exceeds the preset opening deviation threshold, the DCS controller sends a valve deviation alarm signal to the host computer and records the real-time reaction temperature, the target set value, the valve opening control quantity, and the actual opening value at the current moment, storing them as a valve deviation event log in the local memory of the DCS controller.

6. The DCS control method for coking inhibitors according to claim 1, characterized in that, Based on the target production formula data, a first set of control parameters for the intermediate synthesis stage and a second set of control parameters for the compounding stage are decomposed, including: The DCS controller parses the target production formula data to obtain the first target mass of T154 additive, the second target mass of benzaldehyde, the third target mass of 2,6 phenol, and the fourth target mass of toluene required for the intermediate synthesis stage, and uses the first target mass, the second target mass, the third target mass, and the fourth target mass as the first set of control parameters. The DCS controller parses the target production formula data to obtain the fifth target mass of the high-boiling-point aromatic solvent, the sixth target mass of the coking inhibitor intermediate, and the seventh target mass of the T203 additive required for the compounding stage, and uses the fifth target mass, the sixth target mass, and the seventh target mass as the second set of control parameters.

7. The DCS control method for coking inhibitors according to claim 6, characterized in that, Based on the first set of control parameters, before the control valve sequentially adds T154 additive, benzaldehyde, and 2,6-phenol to the reactor, the following steps are also included: The DCS controller acquires the empty vessel mass of the reactor and calculates the total feed mass based on the empty vessel mass and the first target mass, second target mass, third target mass and fourth target mass in the first control parameter set; The DCS controller sends a tare command to the weighing module at the bottom of the reactor, causing the weighing module to zero out its current mass. After the weighing module zeros out its mass, it sends a feeding preparation ready signal to the host computer.

8. The DCS control method for a coking inhibitor according to claim 7, characterized in that, The control valve sequentially adds T154 additive, benzaldehyde, and 2,6-phenol to the reactor, including: The DCS controller opens the first regulating valve connected to the T154 additive storage tank and reads the first current mass value of the weighing module in real time. When the first current mass value reaches the first target mass, the first regulating valve is closed. The DCS controller opens the second regulating valve connected to the benzaldehyde storage tank and reads the second current mass value of the weighing module in real time. When the second current mass value reaches the sum of the second target mass and the first target mass, the second regulating valve is closed. The DCS controller opens the third regulating valve connected to the 2,6 phenol storage tank and reads the third current mass value of the weighing module in real time. When the third current mass value reaches the sum of the third target mass, the second target mass and the first target mass, the third regulating valve is closed.

9. The DCS control method for coking inhibitors according to claim 4, characterized in that, The proportional gain, integral time, and derivative time of the PID algorithm are set in segments according to different reaction process intervals in the intermediate synthesis stage, and the DCS controller automatically switches the corresponding PID parameter group according to the preset rate interval in which the current water separation rate is located.

10. A DCS control system for a coking inhibitor, 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, it implements the steps of the DCS control method for coking inhibitors as described in any one of claims 1 to 9.

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