CN114253130B - Active disturbance rejection control structure and control method for binary rectification process - Google Patents
Active disturbance rejection control structure and control method for binary rectification process Download PDFInfo
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Abstract
The invention provides an active disturbance rejection control structure and method for a binary rectification process, and belongs to the technical field of energy-saving control of chemical rectification processes. The technical problems that various external disturbances exist in the existing rectification process, deviation occurs in various states in a rectification tower, energy is wasted in the process, and product quality is affected are solved. The technical scheme is as follows: a control structure of purity and quality of a binary rectifying tower product comprises four control loops: a condenser liquid level control loop, a reboiler liquid level control loop, a tower top light component output concentration control loop and a tower bottom light component output concentration control loop; the control method comprises the following steps: the control of four control loops is realized by designing four active disturbance rejection controllers. The invention has the beneficial effects that: the control method has low dependence on a mathematical model in the rectification process, can realize the set value tracking of the concentration of the product at the top and the bottom of the tower, and ensures that the purity of the product is less influenced under the condition of great disturbance of the feeding flow or the components, and has stronger robustness and stability.
Description
Technical Field
The invention relates to the technical field of energy-saving control in a chemical rectification process, in particular to an active disturbance rejection control structure and method in a binary rectification process.
Background
The petrochemical industry is a large energy consumption household, wherein the rectification process is one of high energy consumption representatives in the petrochemical process. Although the rectification technology is widely applied, the energy consumption of the rectification process accounts for 67% of the energy consumption of the whole petrochemical industry and 3% of the energy consumption of the world according to statistics. The energy utilization rate in the rectification process is extremely low, and 80-90% of energy in the whole process is wasted. This limits the sustainable development of the petrochemical industry. Therefore, it is very important to research the energy-saving technology of the rectification process.
The energy-saving rectification technology is mainly divided into two types. One is to recover heat energy, the other is to reduce the loss of effective energy in the rectification process, and the states of pressure, temperature, concentration and the like in the tower are all stabilized in a reasonable range. This requires a safe and reliable automatic control system to be fitted. Because various external disturbances exist in the rectification process, if the control system of the rectification process is unreasonable in design, various states in the rectification tower can deviate, so that the energy in the process is wasted, and the product quality is also influenced. The disturbance rejection capability of a rectification process control system has been a hot issue concerned by the chemical industry. A control system with strong anti-interference capability can save a large amount of energy for the rectification process and can ensure the purity requirement of the product.
Disclosure of Invention
The invention aims to provide an active disturbance rejection control structure and a control method for a binary rectification process, the method can still enable the whole tower to be fast and stable when the feeding flow and the feeding concentration fluctuate by 20 percent, and the purity requirement of a product is ensured.
The invention is realized by the following measures: the active disturbance rejection control structure for the binary rectification process comprises a condenser liquid holdup control loop, a reboiler liquid holdup control loop, a tower bottom light component output liquid phase concentration control loop and a tower top light component output liquid phase concentration cascade control loop.
The condenser liquid holdup control loop comprises a first liquid level sensor, a first controller and a tower top discharging pump which are arranged in a condenser, wherein the output end of the first liquid level sensor is connected with the port of the first controller, and the port of the controller is connected with the electric control driving end of the tower top discharging pump.
The reboiler liquid holdup control loop comprises a second liquid level sensor, a second controller and a tower bottom discharging pump which are arranged in the reboiler, the output end of the second liquid level sensor is connected with the control end of the second controller, and the second controller is connected with the electric control driving end of the tower bottom discharging pump.
The liquid phase concentration control loop of the light component product at the bottom of the tower comprises a liquid level sensor II, a temperature sensor I, a pressure sensor I, a controller III and a gas regulating valve, wherein the liquid level sensor II, the temperature sensor I, the pressure sensor I and the output end of the controller III are arranged in a reboiler, the output end of the liquid level sensor II, the output end of the temperature sensor I and the output end of the pressure sensor I are connected with a controller three control interface, and the controller III is connected with a valve electric control driving end of the gas regulating valve.
The control loop comprises a first liquid level sensor, a second temperature sensor, a second pressure sensor, a fourth controller, a tower top reflux pump, a third temperature sensor, a third pressure sensor and a third liquid level sensor which are arranged in the condenser, wherein the third temperature sensor, the third pressure sensor and the third liquid level sensor are arranged on N-1 layers of tower plates, the second temperature sensor, the third temperature sensor, the second pressure sensor, the third pressure sensor, the first liquid level sensor, the third liquid level sensor and the fourth controller are connected, and the fourth controller is connected with an electric control driving end of the tower top reflux pump.
In order to better achieve the above object, the present invention further provides a control method of an active disturbance rejection control structure in a binary rectification process, the control method utilizes data of a first temperature sensor, a second temperature sensor, a third temperature sensor, a first pressure sensor, a second pressure sensor and a third pressure sensor in a liquid phase concentration cascade control loop of a light component output product at the bottom of a tower and a liquid phase concentration cascade control loop of a light component output product at the top of the tower, and obtains the concentration of the light component output product according to an Antoine equation (1) and a gas-liquid phase equilibrium equation (2):
y i (k)＝αx i (k)/(1+(α-1)x i (k)) (2)
wherein x is i (k) And y i (k) Respectively represents the concentration of the light component output of the ith layer of the tower plate in the liquid phase and the gas phase at the kth sampling moment, P i (k) And T i (k) Respectively representing the pressure and the temperature of the ith layer tower plate at the kth sampling moment, wherein the value range of i is {1, N-1, N }, i = D = N represents a condenser, i = B =1 represents a reboiler, alpha is relative volatility, and a, B and c areAn Anthony constant.
Further, the liquid holdup M was measured by a condenser D Taking the outflow rate D of the tower top material as a manipulated variable, and calculating the controlled variable D = u according to the following formula by adopting an Active Disturbance Rejection Control (ADRC) controller as a first controller 1 The outflow rate of (c):
u 1 (k)＝[k 1 (r 1 (k)-z 1 (k))-z 2 (k)]/b 1 (4)
wherein, the formula (3) is an Extended State Observer (ESO) of the condenser liquid holding control loop, z 1 (k) Liquid holdup M for condenser D An observed value of z 2 (k) To control the observed value of the total disturbance of the loop, r 1 (k) Is a controlled variable M D Set value of (b) 1 ＝-1，u 1 ＝D，ω 1 To expand the adjustable gain parameter of the state observer, equation (4) is the active disturbance rejection control law of the control loop, k 1 Is an adjustable feedback control law parameter.
Further, the reboiler liquid holdup M was used B Taking the tower bottom discharge rate B as a manipulated variable and the active disturbance rejection controller as a second controller, wherein the second controller is a controlled variable and obtains a controlled variable B = u according to the following formula 2 The outflow rate of (c):
u 2 (k)＝[k 2 (r 2 (k)-z 3 (k))-z 4 ]/b 2 (6)
wherein, the formula (5) is an extended state observer of the reboiler holding liquid control loop, z 3 (k) Liquid holdup M for reboiler B An observed value of z 4 (k) To control the observed value of the total disturbance of the loop, r 2 (k) For a controlled variable M B Set value of (b) 2 ＝-1，u 2 ＝B，ω 2 In order to expand the adjustable gain parameter of the state observer, equation (6) is the active disturbance rejection control law of the control loop, k 2 Is an adjustable feedback control law parameter.
Further, the liquid phase concentration x of the light component material at the bottom of the tower is used B As a controlled variable, with a steam generation rate V B For the manipulated variable, the third controller adopts an active disturbance rejection controller, and obtains a control quantity V according to the following formula B ＝u 3 The outflow rate of (c):
u 3 (k)＝[k 3 (r 3 (k)-z 5 (k))-z 6 (k)]/b 3 (k) (8)
wherein, the formula (7) is an extended state observer of a tower bottom light component material concentration control loop, z 5 (k) Is x B An observed value of z 6 (k) To control the observed value of the total disturbance of the loop, r 3 (k) Is a controlled variable x B Set value of (b) 3 (k)＝(x B (k)-y 1 (k))/M B (k)，u 3 ＝V B ，ω 3 For expanding the adjustable gain parameter of the state observer, equation (8) is the active disturbance rejection control law of the control loop, k 3 Is an adjustable feedback control law parameter.
Further, an outer ring main controller of the fourth controller uses the concentration x of the light component material liquid phase at the tower top D The output of the outer ring main controller is used as the set value of the inner ring control loop as the controlled variable, and the inner ring secondary controller uses the gas phase concentration y of the light component material of the N-1 layer tower plate N-1 As a controlled variable, at the condensate reflux rate L T For the manipulated variable, the controller adopts an active disturbance rejection controller, and the controlled variable L is obtained according to the following formula T ＝u 5 The reflux rate of (c):
u 4 (k)＝[k 4 (r 4 (k)-z 7 (k))-z 8 (k)]/b 4 (k) (10)
u 5 (k)＝[k 5 (u 4 (k)-z 9 (k))-z 10 (k)]/b 5 (k) (12)
wherein, the formula (9) and the formula (11) are extended state observers of the main and auxiliary circuits for controlling the concentration cascade of the light component output at the tower top, z 7 (k) Is x D An observed value of z 8 (k) Is an observed value of the total disturbance of the primary control loop, z 9 (k) Is y N-1 An observed value of z 10 (k) Is an observed value of the total disturbance of the secondary control loop, r 4 (k) Is a controlled variable x B Set value of (b) 4 (k)＝V B (k)/M D (k)，
ω 4 And ω 5 For the adjustable gain parameters of the inner and outer ring extended state observer, the equations (10) and (12) are the active disturbance rejection control law of the inner and outer ring control loop, k 4 And k 5 Is an adjustable feedback control law parameter.
Further, the bandwidth parameter omega of the extended state observer 1 ，ω 2 ，...，ω 5 The active disturbance rejection controller can accurately estimate the system disturbance.
Further, a feedback control rate parameter k 1 ，k 2 ，...，k 5 The whole tower can be quickly and stably operated when external disturbance occurs, and the requirement on the purity of the product is ensured.
Compared with the prior art, the invention has the following beneficial effects:
1) The control method can realize the liquid level control of the condenser and the reboiler in the rectification process and the set value tracking of the concentration of the light component products at the top and the bottom of the tower, can observe the coupling influence among all loops of the system in real time through the designed extended state observer, and enhances the decoupling performance when the set value tracking of the concentration loops of the light component products at the top and the bottom of the tower is carried out.
2) The control method can observe and compensate the influence of external disturbance of the system in real time through the designed extended state observer, and can realize that the whole tower can still be quickly and stably stabilized when the feeding flow and the feeding concentration fluctuate by 20 percent, thereby ensuring the purity requirement of products and improving the economic benefit of the rectification process.
3) The invention has low dependence degree on a mathematical model in the rectification process, the designed controller has stronger robustness, the control structure is simple, the parameters of the controller needing to be adjusted are less, the engineering realization is easy, and the invention has larger practical application value.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
FIG. 1 is a schematic diagram of a binary distillation process according to embodiment 1 of the present invention
Fig. 2 is a block diagram of a control structure of a binary rectification process provided in embodiment 1 of the present invention.
Fig. 3 is a graph showing the change in light product concentration at both ends when the set point for the top light product concentration was changed from 0.99 to 0.995 and the set point for the bottom light product concentration was changed from 0.01 to 0.005 in example 2 of the present invention.
Fig. 4 is a graph showing the concentration change of the light component products at both ends after 20% disturbance of the feed flow rate, when the set value of the light component product concentration at the top of the column is 0.99, the set value of the light component product concentration at the bottom of the column is 0.01 in example 3 of the present invention.
Fig. 5 is a graph showing the concentration change of the light component product at two ends after 20% disturbance of the feed concentration, when the set value of the light component product at the top of the column is 0.99, the set value of the light component product at the bottom of the column is 0.01, in example 4 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
Referring to fig. 1 to 2, the technical scheme provided by the invention is a control structure and a control method of a rectifying tower in a binary rectifying process, and fig. 1 is a structural schematic diagram of the binary rectifying process. In the figure, a mixture enters the tower from a feed inlet in the middle of the tower, the upper area of the feed inlet is generally called a rectifying section, the lower area of the feed inlet is generally called a stripping section, a light component product is extracted from a condenser at the top of the rectifying section, and a heavy component is extracted from a tower kettle.
Taking the binary rectifying tower for separating the benzene-toluene mixture as an example, the light component benzene is extracted from the tower top, and the heavy component toluene is extracted from the tower bottom.
Fig. 2 shows the control structure, which is composed of 4 active disturbance rejection control loops: the condenser liquid holdup control loop comprises a first liquid level sensor, a first controller and a tower top discharging pump, wherein the first liquid level sensor, the first controller and the tower top discharging pump are arranged in the condenser, the output end of the first liquid level sensor is connected with a port of the controller, and the port of the controller is connected with an electric control driving end of the tower top discharging pump. Liquid holdup M by condenser D Taking the material outflow rate D of a discharge pump at the top of the tower as a manipulated variable, and calculating a controlled variable D = u by adopting an active disturbance rejection controller according to the following formula 1 The outflow rate of (c):
u 1 (k)＝[k 1 (r 1 (k)-z 1 (k))-z 2 (k)]/b 1 (2)
wherein, the formula (1) is an extended state observer of the condenser liquid holding control loop, M D (k) The k sampling moment is measured by a liquid level sensor in the tower top condenser, z 1 (k) Liquid holdup M for condenser D Am ofMeasured value, z 2 (k) For the observed value, r, of the total disturbance of the condenser liquid holdup control loop 1 (k) Is a set value of the liquid holdup of the condenser, b 1 ＝-1，u 1 For manipulating variable quantity of material outflow rate D, omega of discharge pump at tower top 1 To expand the adjustable gain parameter of the state observer. Equation (2) is the active disturbance rejection control law, k, of the control loop 1 Is an adjustable feedback control law parameter.
Preferably, the reboiler liquid holdup control loop comprises a second liquid level sensor, a second controller and a tower bottom discharge pump which are arranged in the reboiler, wherein the output end of the second liquid level sensor is connected with the control end of the second controller, the control end of the controller is connected with the electric control driving end of the tower bottom discharge pump, and the liquid holdup M of the reboiler is used for controlling the liquid holdup M of the reboiler B The material outflow rate B of a tower bottom discharge pump is used as a manipulated variable for a controlled variable, an active disturbance rejection controller is adopted as a second controller, and the controlled variable B = u is obtained according to the following formula 2 The outflow rate of (c):
u 2 (k)＝[k 2 (r 2 (k)-z 3 (k))-z 4 ]/b 2 (4)
wherein, the formula (3) is an extended state observer of the reboiler holding the liquid control loop, M B (k) The k sampling time is measured by a liquid level sensor II in the reboiler at the bottom of the tower, and z is 3 (k) Liquid holdup M for reboiler B Observed value of (a), z 4 (k) Is an observed value of the total disturbance of the liquid holdup control loop of the reboiler r 2 (k) For a controlled variable M B (k) Set value of (b) 2 ＝-1，u 2 For manipulating the material outflow rate B, omega of the variable tower bottom discharge pump 2 The adjustable gain parameter is extended to the state observer. Equation (4) is the active disturbance rejection control law, k, of the control loop 2 Is an adjustable feedback control law parameter.
Preferably, the liquid phase concentration control loop of the light component output at the bottom of the tower comprises a second liquid level sensor and a temperature sensor which are arranged in the reboilerThe device comprises a first degree sensor, a first pressure sensor, a third controller and a gas regulating valve, wherein a second liquid level sensor, a first temperature sensor, a first pressure sensor output end and a third controller interface are connected, the third controller is connected with a valve electric drive end of the gas regulating valve, and a liquid phase concentration control loop of light component materials at the tower bottom controls the liquid phase concentration x of the light component materials at the tower bottom B The steam generation rate V controlled by a gas regulating valve is a controlled variable B For the manipulated variable, the third controller adopts an active disturbance rejection controller, and the controlled variable V is obtained according to the following formula B ＝u 3 The outflow rate of (c):
y i (k)＝αx i (k)/(1+(α-1)x i (k)) (6)
u 3 (k)＝[k 3 (r 3 (k)-z 5 (k))-z 6 (k)]/b 3 (k) (8)
wherein, the formula (7) is an extended state observer of a tower bottom light component material concentration control loop, x B (k) Measured value T from temperature sensor in reboiler B (k) And a pressure sensor-measured value P B (k) Calculated by substituting formula (5) to obtain z 5 (k) Is x B (k) An observed value of z 6 (k) To control the observed value of the total disturbance of the loop, r 3 (k) Is the liquid phase concentration x of light component material at the bottom of the tower B Set value of (b) 3 (k)＝(x B (k)-y 1 (k))/M B (k)，u 3 ＝V B ，M B (k) Measured by a liquid level sensor II in the reboiler, y 1 (k) From x B (k) Calculated by substituting formula (6) to obtain omega 3 To expand the adjustable gain parameter of the state observer. Equation (8) is the active disturbance rejection control law, k, of the control loop 3 For adjustable feedback controlAnd (4) controlling the law parameters.
Preferably, the cascade control loop for the liquid phase concentration of the light component product at the top of the tower comprises a first liquid level sensor, a second temperature sensor, a second pressure sensor, a fourth controller, a reflux pump at the top of the tower, and a third temperature sensor, a third pressure sensor and a third liquid level sensor which are arranged on the tower plates of the N-1 layer, wherein the second temperature sensor, the third temperature sensor, the second pressure sensor, the third pressure sensor, the first liquid level sensor, the third liquid level sensor and a control port of the fourth controller are connected, and the fourth controller is electrically connected with an electric control driving end of the reflux pump at the top of the tower. The outer ring main controller uses the concentration x of the light component material liquid phase at the tower top D The output of the fourth controller is used as the set value of the inner ring control loop as the controlled variable, and the inner ring secondary controller uses the gas phase concentration y of the light component material of the N-1 layer tower plate N-1 As a controlled variable, with the condensate reflux rate L T For the manipulated variable, the controller IV adopts an active disturbance rejection controller, and the controlled variable L is obtained according to the following formula T ＝u 5 The reflux rate of (c):
u 4 (k)＝[k 4 (r 4 (k)-z 7 (k))-z 8 (k)]/b 4 (k) (10)
u 5 (k)＝[k 5 (u 4 (k)-z 9 (k))-z 10 (k)]/b 5 (k) (12)
wherein x is D (k) The measured values of a second temperature sensor and a second pressure sensor in the tower top condenser are calculated by substituting the formula (5), and y is N-1 (k) And the measurement values of the temperature sensor III and the pressure sensor III of the N-1 layer tower plate are obtained by calculation instead of the formula (5) and the formula (6). The formulas (9) and (11) are the expansion shapes of the main and auxiliary loops for controlling the concentration cascade of the light component output at the tower topState observer, z 7 (k) Is x D Observed value of (a), z 8 (k) Is an observed value of the total disturbance of the primary control loop, z 9 (k) Is y N-1 Observed value of (a), z 10 (k) Is an observed value of the total disturbance of the secondary control loop, r 4 (k) Is a set value of the concentration of the light component output at the top of the tower, b 4 (k)＝V B (k)/M D (k)，
M D (k) And M N-1 (k) Measured by a first liquid level sensor and a third liquid level sensor of a condenser and an N-1 layer tower plate, x D (k) And x N-1 (k) The method is obtained by calculating a formula (5) by substituting the temperature sensor II, the temperature sensor III, the pressure sensor II and the pressure sensor III of the tower plates of the N layers and the N-1 layer. Omega 4 And omega 5 And the adjustable gain parameters of the inner and outer ring extended state observers. Equations (10) and (12) are the active disturbance rejection control law, k, of the inner and outer loop control loops 4 And k 5 Is an adjustable feedback control law parameter.
Example 2
The benzene-toluene mixture was separated using the binary rectification column of example 1 with a control structure and control method. The rectifying tower is designed to have 41 layers, wherein 39 layers of tower plates, 1 reboiler and 1 condenser are contained, and feed inlets are formed in 21 layers of tower plates. After the binary distillation tower runs stably, the concentration set value of the light component product at the top of the tower is changed from 0.99 to 0.995 at t =20min, the concentration set value of the light component product at the bottom of the tower is changed from 0.01 to 0.005 at t =100min, and the liquid holdup of a condenser and a reboiler is kept unchanged. The liquid hold-up and the change in the concentration of the light ends product are shown in FIG. 3. As can be seen from FIG. 3, under this control method, the light component product concentrations at the top and bottom of the column can be adjusted to the set values within 20min, the absolute values of the concentration fluctuation under the influence of coupling are respectively less than 0.0001 and 0.00028, the liquid holdups of the condenser and reboiler can be restored to the set values within 30min after the influence of coupling, and the absolute values of the maximum fluctuation are respectively less than 0.026 and 0.018. This shows that the control structure and the control method have good set value tracking performance and stability.
Example 3
The benzene-toluene mixture was separated using the binary rectification column of example 1 with a control structure and control method. After the binary rectifying tower runs stably, the feed flow rate is increased by 20% when t =20min, and fig. 4 shows the liquid holdup of the condenser and the reboiler and the concentration change of light component products at two ends. As can be seen from FIG. 4, under this control method, the light component product concentrations at the top and bottom of the column were restored to the set values at 100min, with the absolute values of the maximum fluctuations being less than 0.0001 and 0.00015, respectively. The liquid holdup of the condenser and the reboiler can be recovered to a set value within 60min after being influenced by interference, and the absolute values of the maximum fluctuation are respectively less than 0.0017 and 0.0011. This shows that the control structure and the control method have good robust performance and stability.
Example 4
After the binary rectifying tower with the control structure and the control method of example 1 is adopted to separate the benzene-toluene mixture, the light component feeding concentration is increased by 20% when t =100min after the binary rectifying tower is stably operated, and the liquid holdup of a condenser and a reboiler and the concentration change of light component products at two ends are shown in fig. 5. As can be seen from FIG. 5, under this control method, the overhead and bottom light component product concentrations returned to the set values at 60min with the absolute values of the maximum fluctuations being less than 0.000002 and 0.000025, respectively. The liquid holdup of the condenser and the reboiler can be recovered to a set value within 40min after being influenced by interference, and the absolute values of the maximum fluctuation are respectively less than 0.0013 and 0.0014. This shows that the control structure and the control method have good robust performance and stability.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (1)
1. An active disturbance rejection control structure for a binary rectification process is characterized in that the control structure consists of a condenser liquid hold control loop, a reboiler liquid hold control loop, a tower bottom light component output liquid phase concentration control loop and a tower top light component output liquid phase concentration cascade control loop;
the condenser liquid holdup control loop comprises a first liquid level sensor, a first controller and a tower top discharge pump which are arranged in a condenser, wherein the output end of the first liquid level sensor is connected with the port of the first controller, and the port of the controller is connected with the electric control driving end of the tower top discharge pump;
the reboiler liquid holdup control loop comprises a second liquid level sensor, a second controller and a tower bottom discharge pump which are arranged in the reboiler, the output end of the second liquid level sensor is connected with the control end of the second controller, and the second controller is connected with the electric control driving end of the tower bottom discharge pump;
the liquid phase concentration control loop of the light component product at the tower bottom comprises a liquid level sensor II, a temperature sensor I, a pressure sensor I, a controller III and a gas regulating valve which are arranged in a reboiler, the output ends of the liquid level sensor II, the temperature sensor I and the pressure sensor I are connected with a controller three control interface, and the controller III is connected with a valve electric control driving end of the gas regulating valve;
the control loop comprises a first liquid level sensor, a second temperature sensor, a second pressure sensor, a fourth controller, a tower top reflux pump, a third temperature sensor, a third pressure sensor and a third liquid level sensor which are arranged in the condenser, the third temperature sensor, the third pressure sensor and the third liquid level sensor are arranged on N-1 layers of tower plates, the first liquid level sensor, the third liquid level sensor, the second temperature sensor, the third temperature sensor, the second pressure sensor, the third pressure sensor and the fourth controller are connected, and the fourth controller is connected with an electric control driving end of the tower top reflux pump;
the control method of the active disturbance rejection control structure in the binary rectification process utilizes data of a temperature sensor I, a temperature sensor II and a temperature sensor III as well as a pressure sensor I, a pressure sensor II and a pressure sensor III in a tower bottom light component output liquid phase concentration cascade control loop and a tower top light component output liquid phase concentration cascade control loop to deduce the concentration of the corresponding tower plate light component output according to an Antoine equation (1) and a gas-liquid phase equilibrium equation (2):
y i (k)＝αx i (k)/(1+(α-1)x i (k)) (2)
wherein x is i (k) And y i (k) Respectively represents the concentration of the light component output of the ith layer of the tower plate in the liquid phase and the gas phase at the kth sampling moment, P i (k) And T i (k) Respectively representing the pressure and the temperature of the ith layer of tower plate at the kth sampling moment, wherein the value range of i is {1, N-1, N }, i = D = N represents a condenser, i = B =1 represents a reboiler, alpha is relative volatility, and a, B and c are Antoni constants;
liquid holdup M by condenser D Taking the outflow rate D of the materials at the top of the tower as a manipulated variable, and solving a controlled quantity D = u by adopting an active disturbance rejection controller according to the following formula by using a controller I 1 The outflow rate of (c):
u 1 (k)＝[k 1 (r 1 (k)-z 1 (k))-z 2 (k)]/b 1 (4)
wherein, the formula (3) is an extended state observer of the condenser liquid holding amount control loop, z 1 (k) Liquid holdup M for condenser D Observed value of (a), z 2 (k) To control the observed value of the total disturbance of the loop, r 1 (k) For a controlled variable M D Set value of (b) 1 ＝-1，u 1 ＝D，ω 1 For expanding the adjustable gain parameter of the state observer, equation (4) is the active disturbance rejection control law of the control loop, k 1 Is an adjustable feedback control law parameter;
liquid holdup M by reboiler B Taking the tower bottom discharge rate B as a manipulated variable and the active disturbance rejection controller as a second controller, wherein the second controller is a controlled variable and obtains a controlled variable B = u according to the following formula 2 The outflow rate of (c):
u 2 (k)＝[k 2 (r 2 (k)-z 3 (k))-z 4 ]/b 2 (6)
wherein, the formula (5) is an extended state observer of the reboiler holding liquid control loop, z 3 (k) Liquid holdup M for reboiler B Observed value of (a), z 4 (k) To control the observed value of the total disturbance of the loop, r 2 (k) For a controlled variable M B Set value of (b) 2 ＝-1，u 2 ＝B，ω 2 In order to expand the adjustable gain parameter of the state observer, equation (6) is the active disturbance rejection control law of the control loop, k 2 Is an adjustable feedback control law parameter;
the liquid phase concentration x of the light component material at the bottom of the tower is used B As a controlled variable, with a steam generation rate V B For the manipulated variable, the third controller adopts an active disturbance rejection controller, and the controlled variable V is obtained according to the following formula B ＝u 3 The outflow rate of (c):
u 3 (k)＝[k 3 (r 3 (k)-z 5 (k))-z 6 (k)]/b 3 (k) (8)
wherein, the formula (7) is an extended state observer of a tower bottom light component material concentration control loop, z 5 (k) Is x B An observed value of z 6 (k) To control the observed value of the total disturbance of the loop, r 3 (k) Is a controlled variable x B Set value of (b) 3 (k)＝(x B (k)-y 1 (k))/M B (k)，u 3 ＝V B ，ω 3 To expand the adjustable gain parameter of the state observer, equation (8) is the active disturbance rejection control law of the control loop, k 3 Is an adjustable feedback control law parameter;
the outer ring main controller uses the concentration x of the light component material liquid phase at the tower top D The output of the main controller IV is used as the set value of an inner ring control loop as a controlled variable, and the inner ring secondary controller uses the gas phase concentration y of the light component material of the N-1 layer tower plate N-1 As a controlled variable, with the condensate reflux rate L T For manipulating variable, the controller adopts an active disturbance rejection controller, and the control quantity L is obtained according to the following formula T ＝u 5 The reflux rate of (c):
u 4 (k)＝[k 4 (r 4 (k)-z 7 (k))-z 8 (k)]/b 4 (k) (10)
u 5 (k)＝[k 5 (u 4 (k)-z 9 (k))-z 10 (k)]/b 5 (k) (12)
wherein, the formula (9) and the formula (11) are extended state observers of the main and auxiliary circuits for controlling the concentration cascade of the light component output at the tower top, z 7 (k) Is x D An observed value of z 8 (k) Is an observed value, z, of the total disturbance of the primary control loop 9 (k) Is y N-1 Observed value of (a), z 10 (k) Is an observed value of the total disturbance of the secondary control loop, r 4 (k) Is a controlled variable x B Set value of (b) 4 (k)＝V B (k)/M D (k)，
ω 4 And ω 5 For the adjustable gain parameters of the inner and outer ring extended state observers, the equations (10) and (12) are the active disturbance rejection control law of the inner and outer ring control loops, k 4 And k 5 Is an adjustable feedback control law parameter.
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