RU2724772C1 - Control method of process mode of oil mixtures separation by fractionation method - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to oil processing, namely to methods for automated control of fractional columns (FC) with several side samplings to ensure required quality criteria of FC separation products and optimization of technical and economic indices. Method of controlling separation of petroleum mixtures in a rectification column includes calculating quality of products based on calculation of characteristic points of curve of true boiling point fractions of oil mixtures, allowance for specified values of maximum and minimum values of extraction of fractions from rectification column and expertly assigned priorities during extraction of fractions, as well as generation of control actions arriving at fractional column process parameters regulators as correcting ones. Control actions on the regulators are generated using the control module autonomous in relation to the existing control system, which can be transmitted to the existing control system. Module includes a unit for calculating quality indicators, a unit for generating control actions on controllers, configured to allow for restrictions on process parameters and quality indicators, a unit for simulating the effects of changing control actions on regulators. Values of said control actions are calculated automatically in accordance with a logic model of decision making based on information on quality indicators of selected fractions, limitations on process parameters and quality indicators, remoteness of current parameters from restrictions, expertly assigned priorities of selection of fractions. Values of control actions on regulators are transmitted from autonomous module to active control system of fractional column via digital communication channels in automated mode, wherein transmission is carried out with the possibility of intervention of operator, which interrupts transmission in case of receipt from the simulation unit of non-satisfying forecast information on consequences of change of control actions on regulators, and changes their values manually.EFFECT: maximizing output of the most valuable fractions of oil products while ensuring their specified quality.1 cl, 8 dwg, 1 ex

Description

The invention relates to the field of oil refining, and in particular, to methods for automated control of distillation columns (RK) with several lateral screenings to provide the required quality criteria for separation products of the RK and to optimize technical and economic indicators.

A known method of controlling the process of primary oil refining in a complex distillation column, which measures the temperature at the inlet and outlet of the air-cooled condenser. The cooling rate is calculated. Estimates of the boiling temperatures are determined taking into account the transport lag along the measuring channels and the side shoulder straps are adjusted (patent RU2040294, IPC B01D 3/42, G05D 27/00, published on July 25, 1995).

A known method of controlling the quality of products for the separation of oil mixtures by the rectification method, including adjusting the quality indicators (PC) of products by calculating the determining parameters of products by technological parameters and calculating the quality indicators of these products from the calculated values of the determining indicators of products, controlling the flow rate and temperature in the apparatus, according to the invention they regulate the level and pressure in the apparatuses, the regulation of the defining indicators of the products is carried out with correction according to the calculated quality indicators of these products. As determining indicators use the characteristic point of the true boiling point (ITC) of the products. When implementing the method, the signals from the sensors enter the computing device, where the values of the characteristic points of the TEC are calculated by calculation. Based on the calculated values of characteristic points (TECs), signals are generated in the computing device, which are then sent to the column regulators as corrective ones. For a given curve (ITC) of products, a multitude of product quality indicators (shoulder straps) can be uniquely determined, for example, flash point and solidification, viscosity (patent RU2065761, IPC B01D 3/42, G05D 27/00, published on 08.27.1996) .

The disadvantages of the known solutions are that on the control parameters, on the basis of one or another information, they act, but the mechanisms for the formation of control actions are not given. Decisions on the choice of the order of use and the method of forming the control intensities are not specified, which does not allow implementing the control in accordance with the inventions unambiguously, in a full and exhaustive manner.

The technical problem solved by the invention is the creation of a method for the automated control of distillation columns with side selection of fractions according to the set of quality indicators of product flows, which improves the accuracy of maintaining quality indicators within specified limits, the possibility of a direct impact on technological parameters through the set values of quality indicators, improving control safety due ensuring compliance with the restrictions on the parameters of the technological regime and monitoring the quality indicators of production products.

EFFECT: maximizing the yield of the most valuable fractions of petroleum products while ensuring their specified quality by using models for calculating PC in the form of characteristic points of the curve of the true boiling points (ITC) of fractions, providing specified values of the maximum and minimum values of fractions from the Republic of Kazakhstan and expertly assigned priorities for selection of fractions.

The technical problem is solved, and the result is achieved by controlling the process of separation of oil mixtures in a distillation column, including the calculation of product quality indicators in the form of boiling points of fractions, based on the calculation of characteristic points of the curve of the true boiling points of fractions of oil mixtures, taking into account the specified values of the maximum and minimum values of fractions from a distillation column and expertly assigned priorities in the selection of fractions, as well as the formation of control actions received by the regulators of the process parameters of the distillation column as corrective ones, while the control actions on the regulators are formed using a control module, which is independent of the existing control system of the distillation column, made with the possibility of their subsequent transfer to the existing control system, and the specified module includes a unit for calculating quality indicators, a forming unit I control actions on the regulators, made with the possibility of taking into account restrictions on technological parameters and quality indicators, a block simulating the effects of changes in the control actions on the regulators, while the values of these control actions are calculated automatically in accordance with the logical decision-making model based on information on the quality indicators of the selected fractions , on restrictions on technological parameters and quality indicators, remoteness of current parameters from restrictions, on expertly assigned priorities for selecting fractions, and the values of control actions on the regulators are transferred from the stand-alone module to the operating distillation column control system via digital communication channels in an automated mode, in which the transmission is carried out with the possibility of operator intervention, which interrupts the transmission in case of receipt from the simulation unit of predictive information that does not satisfy it about the consequences of changes in control actions on the regulators, and changes their values manually.

The invention is illustrated in figures 1-8, which show:

figure 1 is a schematic diagram of a system that implements the inventive method for RK with three side selections;

figure 2 - model of the control process in the form of a Petri net, used to describe the algorithm of the autonomous control module;

in FIG. 3, 4, 5, 6, 7, a specific example of the method is illustrated with the results of machine experiments displayed on a simulator program in an automated mode of operation of an autonomous control module for a column with three lateral selections.

In FIG. Figure 3 shows the mimic diagram at the beginning of a machine experiment, i.e. for the initial state of the Republic of Kazakhstan, when the technological parameters and PC are within specified limits;

figure 4 shows a graph of the flow rate of the second lateral selection - fraction F2;

figure 5 shows a graph of the flow rate of the first lateral selection of the first fraction F1;

figure 6 is a graph of changes in the quality indicator t ₂ ¹⁰ (ten percent boiling point of the second lateral selection);

in FIG. 7 shows a mnemonic diagram at the end of the experiment;

in FIG. 8 shows the operation algorithm of an autonomous control module.

In the figures indicated:

1 - distillation column;

2 - upper fraction (upper product);

3 - lateral selection of the first fraction;

4 - lateral selection of the second fraction;

5 - lateral selection of the third fraction;

6 - selection of the lower fraction (lower product);

7 - irrigation flow;

8 - flow of raw materials;

9, 11, 14, 15, 19, 23, 27 - temperature sensors for raw materials, irrigation, top of the Republic of Kazakhstan, the first, second, third and lower fractions, respectively;

10, 12, 16, 20, 24, 28 — flow rate sensors for raw materials, irrigation, first, second, third and lower fractions, respectively;

13 - pressure sensor top of the Republic of Kazakhstan;

17, 21, 25 - local flow controllers designed to ensure the stability of the costs of the first, second and third fractions, respectively;

18, 22, 26 - control valves of the first, second and third fractions, respectively;

29 - SCADA-system of the existing management system of the Republic of Kazakhstan;

30 - OPC server;

31 - PC calculation unit;

32 - block forming the control actions on the regulators (settings);

33 - block simulating the effects of changes in control actions on the regulators (settings);

34 - channel for transmitting information about the current monitored parameters, organized by the OPC server;

35 - transmission channel of control actions on the regulators transmitted to the SCADA system through the OPC interface;

36 - channel for transmitting forecast information about the process to the operator;

37 - channel for transmitting information about restrictions on a PC from an operator to an autonomous module;

38 - transmission channel information about restrictions on technological parameters;

39 - channel for transmitting settings from the operator to an autonomous control module;

40 - transmission channel information on priorities for the selection of fractions;

41 - channel for transmitting information about the calculated PC;

42 - channel for transmitting information about the settings to the simulation unit 33;

43 - the existing (current) control system of the Republic of Kazakhstan;

44 - stand-alone control module;

45 - operator (“operator" means the human-machine interface of the operator’s workstation).

In FIG. 3-7 are indicated:

46 - name of the mnemonic diagram;

47 - window title;

48 - field for displaying the author of the mnemonic diagram of the control process;

49 - timestamp;

50 - button for changing settings;

51 - screen photograph button;

52 - button for setting the OPC connection;

53 - button for displaying trend windows;

54 - button to launch the model for execution;

55 - field display indicators of product quality;

56 - field display boiling point 10% of the first fraction;

57 - field display temperature boiling point 90% of the first fraction;

58 - field display temperature boiling point 10% of the second fraction;

59 is a display field of a predetermined boiling point of 10% of the second fraction;

60 - field display temperature boiling point 90% of the second fraction;

61 is a display field of a preset boiling point value of 90% of the second fraction;

62 - field display temperature boiling point 10% of the third fraction;

63 is a display field of a predetermined boiling point of 10% of the third fraction;

64 - field display temperature boiling point 90% of the third fraction;

65 is a display field of a preset boiling point value of 90% of the third fraction.

In addition, figure 2 denotes the position P _i , (i = 1,2, ...), which have the meaning of the conditions, and transitions t _i , (i = 1,2, ...) of the network, indicated by bars, which have the meaning of actions:

P ₁ is the initial position, the condition for allowing the algorithm to start;

P ₂ , P ₃ , P ₄ , P ₅ - verification of the conditions L ₂ , L ₃ , H ₂ , H _3, respectively;

P ₆ - P ₁₀ , P ₁₂ - verification of compliance with the restrictions β ₁ , β ₂ , α ₂ , α ₃ , α ₁ and β ₃ ;

R ₁₁ - check the sign of the end of the cycle;

t ₁ - t ₄ - start checking conditions for tasks;

t ₅ - decision to increase F ₁ ;

t ₆ - decision to increase F ₂ ;

t ₇ - decision to reduce F ₂ ;

t ₈ - decision to reduce F ₃ ;

t ₉ - decision to reduce F ₁ ;

t ₁₀ - change F ₁ ;

t ₁₁ - decision to increase F ₃ ;

t ₁₂ is the change in F ₂ ;

t ₁₃ is the change in F ₃ ;

t ₁₄ - the issuance of the message "Management resource exhausted."

It is well known that a complex RC has, as a rule, from 2 to 4 lateral takeoffs, and the values of lateral takeoffs are taken as control parameters. In FIG. Figure 1 shows a schematic diagram of a system for a RC with three lateral withdrawals, but the principles for the formation of control actions are similar for columns with an arbitrary number of lateral withdrawals.

The system for implementing the method (Fig. 1) includes an existing (existing) control system 43 of RK 1 (ACS TP) and an autonomous control module 44 that interacts with the ACS TP through digital communication channels used in the ACS.

It is well known that the control systems of the Republic of Kazakhstan work on the basis of the SCADA system (for example, https://ru.wikipedia.org/wiki/SCADA), which is a software shell in which the existing (existing) control system of the Republic of Kazakhstan (ACS TP) is configured to implement the communication functions with the technological process and the human-machine interface. To organize the exchange of data between the existing control system 43 of the Republic of Kazakhstan and the stand-alone control module 44 through the software OPC interface, an OPC server is used (for example, https://ru.wikipedia.org/wiki/OPC).

The stand-alone control module 44 is designed to generate control actions on the regulators (settings) with their subsequent transfer to the existing control system of the Republic of Kazakhstan and includes a PC calculation unit 31, which operates on the basis of data on the current monitored parameters, for example, the readings of temperature, pressure and flow sensors, received from the SCADA system through the OPC interface; block 32 of the formation of control actions on the regulators, which implements the control algorithm of the RC by PC; block 33 simulating the effects of changes in control actions on the regulators (settings), operating by means of a process simulator program with the function of computing a PC and calculating control actions in a control system that implements a mathematical model of the Republic of Kazakhstan to calculate predictive information about the process.

Autonomous control module 44 is a software implementation of the algorithm for forming controls based on the exchange of information between the current control system 43 of the RK 1 and this module through the OPC server 30 in real time.

The simulator program is designed to simulate the state of the Republic of Kazakhstan, display the status and consequences of the application of control actions on the regulators on the mimic diagram. The simulator program is used both at the stage of debugging the control system and in the automated control mode and allows you to solve the following tasks:

- display of the state of the Republic of Kazakhstan and its reactions to control actions;

- determination (correction) of ranges of change of settings for regulators according to the set restrictions;

- checking the correctness of control algorithms, etc. Using a simulator allows you to increase the safety of process control in an automated mode, because the operator can interrupt the control process at any time if any parameters of the technological mode displayed by the simulator program do not satisfy him.

To describe the operation algorithm of an autonomous control module, a control process model in the form of a Petri net is used (Fig. 2). In accordance with the rules for representing Petri nets, the network positions (they are indicated by circles) represent some conditions under which the corresponding actions are displayed by transitions (they are indicated by bars). Causal relationships between conditions and actions are indicated by arrows (arcs). The control process model describes the logical process of forming settings for fraction flow controllers, taking into account the following options:

1) the priorities ranking the “value” of fractions as a technical and economic indicator: first, the selection of the most “valuable” fraction is maximized, then (within the limits of available management resources) the selection of the second fraction in terms of “value” is maximized, and finally (within the limits of available management resources) ) maximizes the selection of the third fraction; as a result, technical and economic indicators are optimized;

2) the feasibility of management, i.e. the ability to implement the mode without violating the restrictions on technological parameters and PC values;

3) the dependence of the rate of change of controls on how far the parameters of the current technological mode and PC are located from the limitations; the implementation of this option is carried out in terms of fuzzy logic.

The inventive method is as follows.

Raw materials 8 are fed to the column 1, the upper product 2 is discharged from above, the lower product 6 is discharged from below, and side withdrawals of fractions 3,4,5. Sensor 10 measures the consumption of raw materials, sensors 16, 20, 24 measure the costs of side sampling fractions and sensor 28 - the flow rate of the lower product, sensor 9 - the temperature of the raw materials, sensors 14, 15, 19, 23, 27 - the temperature of the upper, first, second, third and the lower fraction, respectively, and the sensor 13 is the pressure at the top of the column.

The signals about the values of temperature, flow, pressure are supplied to the SCADA system 29 of the existing (existing) control system 43 of the Republic of Kazakhstan 1. From the simulation unit 33, information with predictive information about the process is transmitted to channel 45 through channel 36. And information about the parameters of the technological mode from the current system 43 through the SCADA system 29 and the OPC server 30 is transmitted to the PC computing unit 31 of the autonomous control module 44.

When calculating quality indicators in the form of temperatures of characteristic points of the true boiling points of the side sampling fractions, the following relationships are used:

,(1),

,(1),

[начало кипения, 1%-я точка выкипания фракции, 5%-я, 50%, 95%, 99%, конец кипения];where t ^α _j , (the number of selections from 2 to 4), j = 1, 2, 3, 4, α - typical fraction of the distillate, α

[start of boiling, 1% boiling point of the fraction, 5%, 50%, 95%, 99%, end of boiling];

a, b, c, d, e (with indices α, j) - constants for the model corresponding to the fraction of the distillation α and the lateral selection number j;

-температура на тарелке выше тарелки отбора;

-temperature on a plate above the selection plate;

-температура на тарелке ниже тарелки отбора;

-temperature on a plate below the selection plate;

- температура на тарелке отбора.

- temperature on the selection plate.

-давление верха колонны.

-pressure of the top of the column.

This ratio (1) reflects the patterns of communication between PC products and technological parameters, based on the heat balance.

The temperatures for the points of the TEC curve can also be calculated by the ratio:

,(2)

, (2)

where α is the fraction of distillation, b, s, d (with indices) the coefficients of the model for calculating quality indicators;

отборы боковых продуктов выше тарелки отбора;

side product sampling above the sampling plate;

F is the value of the power consumption per column;

- значение относительного парового потока.

- value of relative steam flow.

For the operation of the control system, the following variables and values of restrictions on parameters and indicators are used.

Input variables

Logical variables (3), determined by the output of the PC products (side sampling) of the Republic of Kazakhstan beyond the specified limits:

,

,

, (3)

, (3)

,

,

.

.

Deviations of the PC from the set values:

e ₂ ¹⁰ = | t ₂ ¹⁰ _back - t ₂ ¹⁰ |,

e ₃ ¹⁰ = | t ₃ ¹⁰ _back - t ₃ ¹⁰ |, (4)

e ₂ ⁹⁰ = | t ₂ ⁹⁰ - t ₂ ⁹⁰ _back |,

e ₃ ⁹⁰ = | t ₃ ⁹⁰ - t ₃ ⁹⁰ _back |.

Checking cost limits (5):

, (5)

, (five)

,

,

– номер фракции;

where i

- fraction number;

и

– минимальный и максимальный пределы значений i-го отбора

;

and

- the minimum and maximum limits of the i-th selection

;

– величина окрестности границы расхода (значение запаса по параметру относительно ограничения), которая назначается с учетом точности вычисления параметров и коэффициента, масштабирующего интенсивность изменения управляющих воздействий (уставок) на регуляторы (6).

- the value of the vicinity of the flow boundary (the margin value by the parameter relative to the restriction), which is assigned taking into account the accuracy of the calculation of the parameters and the coefficient that scales the intensity of changes in the control actions (settings) on the controllers (6).

Output variables: control actions for changing the selection of 3.4.5 fractions ΔF _i , i = 1,2,3.

The calculated PCs are transferred to the block 32 for generating control actions on the controllers and the simulation block 33. Information on the values of the restrictions on technological parameters is also sent to block 32 via channel 38 from the operator 45:

= {

,

– минимальный и максимальный пределы значений i-го отбора

, i=1,2,3,

= {

,

- the minimum and maximum limits of the i-th selection

, i = 1,2,3,

- on channel 37 information about restrictions on PC values:

={ t₂ ¹⁰ _зад , t₂ ⁹⁰ _зад , t₃ ¹⁰ _зад ,t₃ ⁹⁰ _зад} - заданные температуры выкипания 10%, 90% для 2-й и 3-й фракций (по технологическим условиям ограничения на ПК 1-й фракции не вводятся),

= {t ₂ ¹⁰ _back , t ₂ ⁹⁰ _back , t ₃ ¹⁰ _back , t ₃ ⁹⁰ _back } - set boiling points 10%, 90% for the 2nd and 3rd fractions (according to the technological conditions, restrictions on PC 1st fractions are not introduced)

- on channel 40 information (signals) on priorities for selection of fractions,

- channel U sends a signal U about the need to interrupt the transfer of settings from the autonomous module 44 to the existing control system 43 of the Republic of Kazakhstan.

^. и ограничений на значения отборов

(изменение уставок регуляторам отбора фракций ΔF_i, i=1,2,3):In block 32, based on the model of the control process in the form of a Petri net (Fig. 2), logical expressions are generated for calculating the increments of control actions on the regulators (settings) based on relation (6), taking into account the specified values of the product quality indicators

^. and restrictions on sampling values

(change of settings for fraction selection controllers ΔF _i , i = 1,2,3):

- e₂ ¹⁰⋅L₂⋅

⋅

–e₃ ¹⁰⋅L₃⋅

⋅

⋅

-e₂ ⁹⁰⋅H₂⋅

⋅

],ΔF ₁ = k⋅ [e ₂ ¹⁰ ⋅L ₂ ⋅

- e ₂ ¹⁰ ⋅L ₂ ⋅

⋅

-E _{March ¹⁰} ⋅L ₃ ⋅

⋅

⋅

-e ₂ ⁹⁰ ⋅H ₂ ⋅

⋅

],

- e₂ ¹⁰⋅L₂⋅

–e₃ ¹⁰⋅L₃⋅

⋅

-e₂ ⁹⁰⋅H₂⋅

–e₃ ⁹⁰⋅H₃⋅

⋅

], (6)ΔF ₂ = k⋅ [e ₃ ¹⁰ ⋅L ₃ ⋅

- e ₂ ¹⁰ ⋅L ₂ ⋅

-E _{March ¹⁰} ⋅L ₃ ⋅

⋅

-e ₂ ⁹⁰ ⋅H ₂ ⋅

-E ₃ ⁹⁰ ₃ ⋅ ⋅H

⋅

], (6)

– e₃ ⁹⁰⋅H₃⋅

–e₃ ¹⁰⋅L₃⋅

],ΔF ₃ = k⋅ [e ₂ ⁹⁰ ⋅H ₂ ⋅

- e ₃ ⁹⁰ ⋅H ₃ ⋅

-E _{March ¹⁰} ⋅L ₃ ⋅

],

,

,

,

,

,

означает операцию «отрицание» («не»), k – коэффициент, масштабирующий интенсивность изменения управляющих воздействий, назначается опытным путем (эвристически) с учетом частоты изменения уставок, так чтобы не возникали интенсивные переходные процессы. Например, при частоте изменения уставки по расходу F2 1/мин. и самой большой постоянной времени (инерционности) каналов «расход – температуры на тарелках» 10 мин., примерное значение коэффициента выбирается в пределахwhere the bar above the logical variables

,

,

,

,

,

means the operation “negation” (“not”), k is the coefficient that scales the intensity of changes in control actions, is assigned empirically (heuristically) taking into account the frequency of changes in the settings, so that there are no intensive transients. For example, at a rate of change of the setpoint for flow rate F2 1 / min. and the largest time constant (inertia) of the channels “flow - temperature on plates” 10 min., the approximate value of the coefficient is selected within

k = [0.01 ÷ 0.05].

The Δ symbol means that the settings are changed for the flow controllers Fi, i = 1,2,3, according to the scheme:

Fij = Fij-1 + ΔFi, where j is the current set-up cycle, j-1 is the previous set-up cycle.

The information on the technological parameters from the OPC server 30 is supplied to the simulation block 33, about the PC from the block 31, and about the controls from the control generation block 32.

The generated settings are transmitted through the OPC server 30 to the local flow controllers 17, 21, 25, designed to ensure the stability of the selection costs, as tasks to the controllers, provided that the operator 45 does not send a signal on channel 39 to interrupt the transfer of the settings to the existing control system 43.

To make decisions on control, the operator 45 receives information about the PC from block 31, about the values of the settings generated by block 32, and also predictive information on the behavior of the RK from the action of control actions received from the simulation block 33.

The control of the technological mode of separation of oil mixtures is carried out in an automated mode, when the generated control actions on the regulators are transmitted through the OPC server to the existing control system 43, provided that the operator 45 does not interrupt the process of changing the control actions. Operator intervention in the control process is possible, if it receives the predictive effects of changes in the information control actions, that he is not satisfied for any reason. As an element with which the operator receives predictive information about the consequences of changes in control actions, there is a simulator program that reproduces the consequences of changes in controls, and the results are displayed on mnemonic diagrams.

A specific embodiment of the method is illustrated in FIG. 3, 4, 5, 6, 7, which display the results of machine experiments on a simulator program in an automated control mode of a distillation column in accordance with FIG.

At the beginning of the experiment (figure 3), the technological parameters and quality indicators have the following meanings:

F _c = 35, m ³ / hour - consumption of raw materials;

T _c = 30 ° C is the temperature of the raw material;

F _about = 42, m ³ / hour - irrigation flow;

P _in = 3, at - pressure of the top of the column;

Т _в = 88.32 ° С - top temperature;

F ₁ = 20, m ³ / h - selection of the 1st fraction;

T ₁ = 150 ° C - the temperature of the 1st fraction;

F ₂ = 20, m ³ / h - selection of the 2nd fraction;

T ₂ = 208 ° C - temperature of the 2nd fraction;

F ₃ = 20, m ³ / h - selection of the 3rd fraction;

T ₃ = 249.5 ° C - temperature of the 3rd fraction;

F _n = 50, m ³ / h - consumption of bottoms;

T _n = 294 ° C is the temperature of the cube.

Indicators of product quality, determined by the claimed method:

t ₁ ¹⁰ = 279.7 ° С - boiling point 10% for the 1st fraction;

t ₁ ⁹⁰ = 367.6 ° С - boiling point 90% for the 1st fraction;

t ₂ ¹⁰ = 350.6 ° С - boiling point 10% for the 2nd fraction;

t ₂ ⁹⁰ = 443,0 ° С - boiling point 90% for the 2nd fraction;

t ₃ ¹⁰ = 418.0 ° С - boiling point 10% for the 3rd fraction;

t ₃ ⁹⁰ = 584.3 ° С - boiling point 90% for the 3rd fraction.

Preset values of product quality indicators:

t ₂ ¹⁰ _ass = 349 ° С - preset boiling point 10% for the 2nd fraction;

t ₂ ⁹⁰ _ass = 444 ° С - preset boiling point of 90% for the 2nd fraction;

t ₃ ¹⁰ _ass = 417 ° С - preset boiling point 10% for the 3rd fraction;

t ₃ ⁹⁰ _ass = 585 ° С - preset boiling point of 90% for the 3rd fraction.

In the initial state, the values of the quality indicators do not go beyond the specified limits, the values of the logical variables L ₂ , L ₃ , H ₂ , H ₃ are 0, and the increments of the settings calculated in block 32 by relation (6) are also 0.

Suppose that the task on the boiling point of 10% for the 2nd fraction increases to 352 ° C. The result is that the predetermined value (t = ^{₁₀ February} _backside 349 ° C) is not satisfied. If you do not fulfill any given restrictions (in this case, t ₂ ¹⁰ ), the simulator program automatically starts. The value of the logical variable changes from 0 to 1: L ₂ = 1, increments in the costs of side sampling of fractions begin to be calculated.

At 4 seconds, the task on the boiling point of 10% for the 2nd fraction increases to 352 ° C. The duration of the experiment is 136 seconds. (2.27 min.). For a real process, the time scale of the transition process can be selected by changing the coefficient k. For example, the real transient time should be 20 minutes, then the value of k in (6) should be reduced by approximately 20 / 2.27 = 8.8 times.

As a result, the flow rate F2 decreases to 15.94, m ³ / h (Fig. 4), the flow rate F1 increases proportionally to 27.37, m ³ / h (Fig. 5), the indicator t ₂ ^{10 is} set to 352 ° C ( Fig. 6). A view of the mimic diagram at the end of the experiment is shown in FIG. 7.

If the operator is not satisfied with the results, he will initiate an interruption of the automatic transition to a new technological mode. Priorities in the selection of fractions are determined by the operator based on market conditions.

The inventive method provides the feasibility of control actions and the adapted formation of their intensity, which takes into account the closeness of the technological mode to the constraints, and also takes into account the priorities of the selection of fractions in such a way that the selection of the most valuable fractions is maximum while ensuring their specified quality and fulfilling technological limitations.

Claims (1)

A method for controlling the process of separating oil mixtures in a distillation column, including calculating product quality indicators in the form of boiling points of fractions, based on the calculation of characteristic points of the curve of the true boiling points of fractions of oil mixtures, taking into account the set values of the maximum and minimum values of fractions from the distillation column and expertly assigned priorities during the selection of fractions, as well as the formation of control actions coming to the regulators of the process parameters of the distillation column as corrective ones, while control actions on the regulators are formed using a control module autonomous with respect to the existing control system of the distillation column, which can be transferred to the existing one a control system, said module including a unit for calculating quality indicators, a unit for generating control actions on the regulators, configured to taking into account restrictions on technological parameters and quality indicators, a unit for simulating the consequences of changes in control actions on regulators, while the values of these control actions are calculated automatically in accordance with a logical decision-making model based on information on quality indicators of selected fractions, on restrictions on technological parameters and indicators quality, remoteness of the current parameters from restrictions, about expertly assigned priorities for selecting fractions, while the values of the control actions on the regulators are transferred from the stand-alone module to the operating distillation column control system through digital communication channels in an automated mode in which the transmission is carried out with the possibility of operator intervention, which interrupts the transmission in case of receipt from the simulation unit of predictive information that does not satisfy it about the consequences of changes in control actions on the regulators, and changes their values manually.

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