CN102073271B - Intelligent control method and system for delayed coking device - Google Patents

Abstract

The invention discloses an intelligent control method for a delayed coking device, which comprises the following steps: S1) setting operating variables of intelligent control of the delayed coking device, an initial value of state marker bit, and thresholds of place value of a feed valve and relative quantity of blowing steam, wherein the relative quantity of the blowing steam is the ratio of the flow rate of the blowing steam to the total feeding flow rate of a heating furnace; S2) acquiring the current place value of the feed valve and the current relative quantity of the blowing steam through a distributed control system, and judging the process step which needs to be performed according to the current place value of the feed valve and the current relative quantity of the blowing steam; and S3) adjusting the operating variables and the state marker bit correspondingly according to the process step, and returning to the step S2) after completing the adjustment. With the adoption of the method, the intelligent compensation control of the delayed coking device can be realized, and the technical problems of single processing of switching disturbance, incapability of realizing intelligentized effective suppression and incapability of performing optimal control during the switching process can be solved.

Description

Intelligent control method and system for delayed coking device

Technical Field

The invention relates to the technical field of petrochemical industry, in particular to an intelligent control method and system for a delayed coking device.

Background

Delayed coking processes are a class of strongly coupled, nonlinear, time-varying, large hysteresis, and multi-constrained processes. With the trend of increasing the proportion of heavy crude oil in crude oil extraction in countries and countries around the world, the demand of heavy fuel oil is increasingly compressed due to the continuous change of consumption structures of petroleum products, the demand of light oil (especially diesel oil) is rapidly increased, the demand of high-quality petroleum coke for manufacturing electrodes for metallurgy, especially ultrahigh-power electrodes is continuously increased, and the delayed coking process is more and more concerned by people. Because the delayed coking process is simple, the raw material adaptability is strong, and the product value is high, the control requirement on the delayed coking process is higher and higher, so as to meet the requirement of maximizing the economic benefit.

Aiming at the production characteristics that the coking of a coke tower needs to be promoted, the coking of a furnace tube needs to be inhibited, the continuous production needs to be ensured, and the periodic intermittent switching needs to be carried out, the degree of automation of the delayed coking device at home and abroad is not high, and the delayed coking device is more obvious at home. First, in the coke drum cutting process, manual experience operation is mainly used, and the effects of different raw materials, different operators, different time for cutting down the drum and the effects on downstream equipment such as a main fractionating tower are different. In addition, the main fractionating tower of the delayed coking belongs to a multi-component and multi-side-line complex fractionating tower, and on one hand, the main fractionating tower has the characteristics of nonlinearity and large hysteresis; on the other hand, periodic coke drum switching operations tend to introduce large disturbances to the overall production process, and conventional Proportional Integral Differential (PID) controllers have difficulty suppressing disturbances effectively. In recent years, various advanced control technologies are widely applied to various chemical processes, and have the advantages of small investment, quick response and the like while improving the economic benefit of enterprises, however, the treatment of switching interference in the advanced control technologies of delayed coking at home and abroad is a little single so far, most of the advanced control technologies are treated as common interference of advanced control, intelligent effective inhibition is not realized, and the switching process is not optimally controlled.

Disclosure of Invention

Technical problem to be solved

The invention aims to solve the technical problems that the automatic control of coking cannot be delayed, the processing of switching interference is single, the intelligent effective inhibition cannot be realized, and the optimized control cannot be performed in the switching process.

(II) technical scheme

In order to solve the technical problem, the invention provides an intelligent control method of a delayed coking device, which comprises the following steps:

s1: setting initial values of an operating variable and a state flag bit intelligently controlled by a delayed coking unit, a feeding valve position and a threshold value of a relative blowing steam quantity, wherein the relative blowing steam quantity refers to a ratio of the blowing steam flow to the total feeding flow of the heating furnace;

s2: acquiring a current feeding valve position value and a current steam blowing relative quantity through a distributed control system, and judging a current process step to be carried out according to the current feeding valve position value and the current steam blowing relative quantity;

s3: and correspondingly adjusting the operation variables and the state flag bits according to the process steps, and returning to the step S2 after the adjustment is finished.

Wherein the operating variables include: the method comprises the following steps of (1) feeding flow of a main fractionating tower, upper feeding flow, middle section circulation flow, heavy wax oil downward returning flow and top circulation flow; the status flag bit includes: preheating a mark bit, a small blowing mark bit and a large blowing mark bit; the threshold values for the feed valve positions include: a normal working condition valve position threshold value, a pressure test valve position threshold value, a preheating second stage valve position threshold value, a preheating third stage valve position threshold value, a small blowing valve position threshold value and a large blowing valve position threshold value; the threshold value of the relative amount of blown steam comprises: the method comprises the steps of normal working condition steam blowing relative quantity threshold value, pressure test steam blowing relative quantity upper limit threshold value, pressure test steam blowing relative quantity lower limit threshold value, preheating steam blowing relative quantity threshold value, preheating second stage steam blowing relative quantity threshold value, preheating third stage steam blowing relative quantity threshold value, small blowing steam blowing relative quantity lower limit threshold value, small blowing steam blowing relative quantity upper limit threshold value and large blowing steam blowing relative quantity threshold value.

Wherein, the step S2 specifically includes the following steps:

s201: acquiring a current feeding valve position value of a first coke tower, a current feeding valve position value of a second coke tower and a current steam blowing relative quantity through a distributed control system;

s202: judging whether to enter a 'normal working condition' process step according to the following logic relation formula (1),

[(V₁+V₂)≤CV₂]&(F_steam≤CF₂) (1)

wherein, V₁Is the current feed level value, V, of the first coke drum₂Is the current feed level value of the second coke drum, F_steamFor the current blowing steamRelative amount, CV₂For said normal operating condition valve position threshold, CF₂Blowing a steam relative quantity threshold value for the normal working condition,&represents a logical and;

if the logical judgment result of the logical relation (1) is true, the process step of 'normal working condition' is judged to be entered, and step S3 is executed, if the logical judgment result is false, step S203 is executed;

s203: judging whether to enter a pressure test process step or not according to the following logical relation (2),

[(V₁+V₂)≤CV₃]&(CF₃₁≤F_steam≤CF₃₂) (2)

wherein, CV is₃For the pressure test valve position threshold, CF₃₁Blowing a lower threshold value of the relative amount of steam for the pressure test, CF₃₂Blowing a steam relative quantity upper limit threshold value for the pressure test;

if the logical judgment result of the logical relation (2) is true, the process enters the "pressure test" step, and step S3 is executed, if the logical judgment result is false, step S204 is executed,

s204: judging whether to enter a preheating process step according to the following logic relation formula (3),

[(V₁+V₂)≥CV₄]&(F_steam≤CF₄) (3)

wherein, CV is₄For said preheating valve position threshold, CF₄A relative amount threshold for the preheat blow steam;

if the logical judgment result of the logical relation (3) is true, it is determined to enter the "preheating" process step, and step S205 is executed, and if the logical judgment result is false, step S208 is executed, where the "preheating" process step includes: the process substeps of "preheating started" and "preheating preparation";

s205: judging whether to enter a 'preheating started' process substep according to the preheating flag bit, if the preheating flag bit is true, judging to enter the 'preheating started' process substep, and executing a step S206, and if the preheating flag bit is false, judging to enter the 'preheating preparation' process substep, and executing a step S3, wherein the 'preheating started' process substep further comprises: the process substeps of a preheating first stage, a preheating second stage and a preheating third stage are carried out;

s206: judging whether to enter a 'preheating first stage' process sub-step according to the following logic relation (4),

(V₁+V₂)≥CV₆ (4)

wherein, CV is₆A second stage preheating valve position threshold value;

if the logical judgment result of the logical relation (4) is false, the process goes into the process substep of "preheating the first stage", and step S3 is executed, if the logical judgment result is true, step S207 is executed;

s207: judging whether to enter a 'second stage of preheating' process substep according to the following logical relation (5),

(V₁+V₂)≥CV₇ (5)

wherein, CV is₇A valve position threshold value of the third stage of preheating;

if the logical judgment result of the logical relation (5) is false, the process substep of 'preheating the second stage' is judged to be entered, and step S3 is executed, and if the logical judgment result is true, the process substep of 'preheating the third stage' is judged to be entered, and step S3 is executed;

s208: judging whether to enter a small blowing process step according to the following logic relation formula (6),

[(V₁+V₂)≥CV₈]&(CF₈₁≤F_steam≤CF₈₂) (6)

wherein, CV is₈For a small blow valve position threshold, CF₈₁Blowing a lower threshold for the relative amount of steam for small blows, CF₈₂Blowing an upper limit threshold of the relative amount of steam for small blowing;

if the logical judgment result of the logical relation (6) is true, the step is judged to enter the small air blowing process step, and the step S209 is executed, if the logical judgment result is false, the step S210 is executed, and the small air blowing process step comprises the following steps: a small air blow started process substep and a small air blow preparation process substep;

s209: judging whether a process substep of 'small air blowing is started' is entered according to the small air blowing flag bit, if the preheating flag bit is true, judging that the process substep of 'small air blowing is started' is entered, and executing a step S3, and if the preheating flag bit is false, judging that the process substep of 'small air blowing preparation' is entered, and executing a step S3;

s210: judging whether to enter a 'big blowing' process step according to the following logic relation formula (7),

[(V₁+V₂)≤CV₁₀]&(F_steam≥CF₁₀) (7)

wherein, CV is₁₀Large blow valve position threshold, CF₁₀Blowing a steam relative quantity threshold value for large blowing;

if the logic judgment result of the logic relation (7) is true, determining to enter a 'large blowing' process step, and executing step S211, and if the logic judgment result is false, determining to enter a 'normal working condition' process step, and executing step S3, wherein the 'large blowing' process step comprises: a process substep of 'large air blowing is started' and 'large air blowing preparation';

s211: and judging whether to enter a process substep of 'large blowing is started' or not according to the large blowing flag bit, if the preheating flag bit is true, judging to enter the process substep of 'large blowing is started', and executing a step S3, and if the preheating flag bit is false, judging to enter a process substep of 'large blowing preparation', and executing a step S3.

Wherein, the step S3 specifically includes:

if the process step of 'normal working condition' is carried out, assigning the preheating flag bit, the small blowing flag bit and the large blowing flag bit as false, and carrying out non-linear liquid level control on the liquid level of the main fractionating tower;

if the pressure test process step is carried out, assigning the preheating flag bit, the small blowing flag bit and the large blowing flag bit as false, and carrying out non-linear liquid level control on the liquid level of the main fractionating tower;

if the 'preheating preparation' process substep in the 'preheating' process step is entered, assigning the preheating flag bit to be true, assigning the small blowing flag bit and the large blowing flag bit to be false, and carrying out nonlinear liquid level control on the liquid level of the main fractionating tower;

if the preheating process sub-step in the preheating process sub-step is started and the preheating first stage process sub-step in the preheating process sub-step is in, assigning the preheating flag bit as true, assigning the small blowing flag bit and the large blowing flag bit as false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower;

if entering the preheating started process sub-step in the preheating process sub-step and being in the preheating second stage process sub-step in the preheating started process sub-step, assigning the preheating flag bit to true, assigning the small blowing flag bit and the large blowing flag bit to false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to the first adjustment amount of the upper feeding flow, adjusting the middle section circulation flow according to the first adjustment amount of the middle section circulation flow, adjusting the flow of the heavy wax oil flowing down and returning to the tower according to the first adjustment quantity of the flow of the heavy wax oil flowing down and returning to the tower, adjusting the top circulating flow according to a first adjusting quantity of the top circulating flow, wherein the first adjusting quantity is a preset percentage of one of the upper feeding flow, the middle section circulating flow, the heavy wax oil downward returning flow and the top circulating flow;

if entering the preheat initiated process sub-step of the preheat initiated process sub-step and being in the preheat third stage process sub-step of the preheat initiated process sub-step, assigning the preheating flag bit to true, assigning the small blowing flag bit and the large blowing flag bit to false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to the second adjustment amount of the upper feeding flow, adjusting the middle section circulation flow according to the second adjustment amount of the middle section circulation flow, adjusting the flow of the heavy wax oil flowing down and returning to the tower according to the second adjustment quantity of the flow of the heavy wax oil flowing down and returning to the tower, adjusting the top circulating flow according to a second adjusting quantity of the top circulating flow, wherein the second adjusting quantity is a preset percentage of one of the upper feeding flow, the middle section circulating flow, the heavy wax oil downward returning flow and the top circulating flow;

if the sub-step of the small blowing preparation process in the process step of small blowing is carried out, assigning the small blowing flag bit as true, assigning the preheating flag bit and the large blowing flag bit as false, and carrying out nonlinear liquid level control on the liquid level of the main fractionating tower;

if the process substep of 'small blowing has started' in the 'small blowing' process step is entered, assigning the small blowing flag bit to true, assigning the preheating flag bit and the large blowing flag bit to false, performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to a third adjustment quantity of the upper feeding flow, adjusting the middle section circulating flow according to a third adjustment quantity of the middle section circulating flow, adjusting the heavy wax oil lower returning flow according to a third adjustment quantity of the heavy wax oil lower returning flow, and adjusting the top circulating flow according to a third adjustment quantity of the top circulating flow, wherein the third adjustment quantity is a preset percentage of one of the upper feeding flow, the middle section circulating flow, the heavy wax oil lower returning flow and the top circulating flow;

if the 'large blowing preparation' process substep in the 'large blowing' process step is entered, assigning the large blowing flag bit to be true, assigning the preheating flag bit and the small blowing flag bit to be false, performing no nonlinear liquid level control on the liquid level of the main fractionating tower, respectively adjusting the adjustment quantities of the upper feeding flow, the middle section circulation flow, the heavy wax oil lower return tower flow and the top circulation flow through iterative learning operation according to the temperature at the bottom of the main fractionating tower, and respectively adjusting the adjustment quantities in the process of respectively adjusting the adjustment quantities, wherein the first adjustment quantity, the second adjustment quantity and the third adjustment quantity are respectively adjusted;

and if the 'large blowing gas starts' process substep in the 'large blowing gas' process step is entered, assigning the large blowing gas flag bit as true, assigning the preheating flag bit and the small blowing gas flag bit as false, and performing no nonlinear liquid level control on the liquid level of the main fractionating tower.

Wherein the nonlinear liquid level control specifically comprises the steps of:

s301: reading the liquid level value at the bottom of the main fractionating tower through the distributed control system, calculating the liquid level change rate at the bottom of the main fractionating tower according to the following relational expression (8),

VelLevel(k)＝Level(k)-Level(k-1) (8)

wherein k is the current control period, VelLevel (k) is the current change rate of the liquid level at the bottom of the main fractionating tower, and Level (k) is the current liquid level value at the bottom of the main fractionating tower;

s302: judging the current area according to the liquid level value at the bottom of the main fractionating tower, wherein the current area is divided into the following five conditions:

if the current main fractionating tower is located in the inner area, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the change rate of the liquid level at the bottom of the current main fractionating tower:

in the case that the liquid level change rate at the bottom of the main fractionating tower is larger than zero, if the following relation (9) is satisfied, the feeding flow rate of the main fractionating tower is adjusted downwards,

Level(k+T_NLC)＞HL (9)

if the following relation (10) is satisfied, the feed rate to the main fractionator is not adjusted,

Level(k+T_NLC)≤HL (10)

when the change rate of the liquid level at the bottom of the main fractionating tower is less than zero, if the following relation (11) is satisfied, the feeding flow of the main fractionating tower is not adjusted,

Level(k+T_NLC)≥LL (11)

if the following relation (12) is satisfied, the feed rate of the main fractionator is adjusted upward,

Level(k+T_NLC)＜LL (12)

in the case where the rate of change of the liquid level at the bottom of the main fractionation column is equal to zero, no adjustment is made to the feed flow to said main fractionation column.

If the current main fractionating tower is positioned in the upper outer region, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is larger than or equal to zero, the feeding flow of the main fractionating tower is adjusted downwards;

under the condition that the liquid level change rate at the bottom of the main fractionating tower is less than zero, the feeding flow of the main fractionating tower is not adjusted;

if the current main fractionating tower is in the lower outer region, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is larger than zero, the feeding flow of the main fractionating tower is not adjusted;

under the condition that the liquid level change rate at the bottom of the main fractionating tower is less than or equal to zero, the feeding flow of the main fractionating tower is adjusted upwards;

if the current position is larger than the outer upper limit area, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is larger than or equal to zero, the feeding flow of the main fractionating tower is adjusted downwards;

in the case that the rate of change of the liquid level at the bottom of the main fractionation column is less than zero, the feed rate to the main fractionation column is adjusted downward if the following relation (13) is satisfied,

Level(k+T_NLC)≥UpBd (13)

if the following relation (14) is satisfied, the feed rate to the main fractionator is not adjusted,

Level(k+T_NLC)＜UpBd (14)

and fifthly, if the current position is in a region smaller than the outer lower limit, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is less than or equal to zero, the feeding flow of the main fractionating tower is adjusted upwards;

when the liquid level change rate at the bottom of the main fractionating tower is larger than zero, if the following relation (15) is satisfied, the feeding flow rate of the main fractionating tower is not adjusted,

Level(k+T_NLC)＞LowBd (15)

if the following relation (16) is satisfied, the feed rate of the main column is adjusted upward

Level(k+T_NLC)≤LowBd (16)

In the above relational expressions (9) to (16), Level (k + T)_NLC)＝Level(k)+VelLevel(k)×T_NLC，T_NLCFor the prediction step length of the liquid level change, HL is a preset liquid level outer upper limit, LL is a preset liquid level outer lower limit, UpBd is a preset liquid level inner upper limit, and LowBd is a preset liquid level inner lower limit.

Wherein, the iterative learning operation specifically comprises:

sampling the temperature of the bottom of the main fractionating tower by a distributed control system, calculating the variance of the temperature of the bottom of the main fractionating tower according to the following formula (17),

<math> <mrow> <mi>D</mi> <msup> <mrow> <mo>(</mo> <mi>h</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>=</mo> <mfrac> <mn>1</mn> <mrow> <mi>n</mi> <mo>-</mo> <mn>1</mn> </mrow> </mfrac> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>0</mn> </mrow> <mi>n</mi> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>T</mi> <mi>i</mi> </msub> <mo>-</mo> <msub> <mi>T</mi> <mi>SP</mi> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>17</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein h is the current iterative learning period, D (h) is the variance of the bottom temperature of the main fractionating tower, n is the number of sampling points, T_iIs the temperature, T, of the ith sampling point at the bottom of the main fractionating tower_SPIs the set value of the temperature at the bottom of the main fractionating tower;

the convergence factor is calculated according to the following formula (18),

<math> <mrow> <mi>&lambda;</mi> <mrow> <mo>(</mo> <mi>h</mi> <mo>)</mo> </mrow> <mo>=</mo> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <mfrac> <mn>1</mn> <mrow> <mo>|</mo> <mi>D</mi> <mrow> <mo>(</mo> <mi>h</mi> <mo>)</mo> </mrow> <mo>-</mo> <mi>D</mi> <mrow> <mo>(</mo> <mi>h</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mo>|</mo> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>18</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein λ (h) is a convergence factor;

calculating the variation of each adjustment quantity of the upper feeding flow, the middle section circulation flow, the heavy wax oil downward returning tower flow and the top circulation flow in the next iterative learning period according to the following formula (19), wherein the variation of the adjustment quantity is calculated respectively by calculating the variation of a first adjustment quantity, a second adjustment quantity and a third adjustment quantity,

ΔR_MVij(h)＝λ(h){K_P[D(h)-D(h-1)]+K_ID(h)+K_D[D(h)-2D(h-1)+D(h-2)]}

-(19)

wherein MVi is the ith operating variable, i is 2, 3, 4, 5, and 2 ~ 5 operating variables correspond in proper order last feed flow, middle section circulation flow, heavy wax oil downward return tower flow and top circulation flow, R_MVij(h) J is the j adjustment quantity of the ith operation variable, j is 1, 2, 3, the 1 st to 3 rd adjustment quantities correspond to the first adjustment quantity, the second adjustment quantity and the third adjustment quantity in sequence, and delta R_MVij(h) Is the variation of the jth adjustment quantity of the ith manipulated variable, K_PIs proportionally adjustable gain, K_IFor integrating the adjustable gain, K_DIs a differential adjustable gain;

calculating the adjustment quantities of the upper feeding flow, the middle section circulation flow, the heavy wax oil downward returning tower flow and the top circulation flow in the next iteration learning period according to the following formula (20),

R_MVij(h+1)＝sgn(R_MVij(h))|ΔR_MVij(h)+|R_MVij(h)|| (20)

wherein, $\mathrm{sgn}\left(R_{\mathrm{MVij}}\left(h\right)\right)=\left\{\begin{array}{c}+1,R_{\mathrm{MVij}}\left(h\right)>0\\ 0,R_{\mathrm{MVij}}\left(h\right)=0\\ -1,R_{\mathrm{MVij}}\left(h\right)<0\end{array}\right.,$

h +1 is the next iterative learning cycle.

In step S2, after the currently required process step is determined, the currently required process step is displayed.

The invention also discloses an intelligent control system of the delayed coking device, which comprises:

the device comprises a setting module, a control module and a control module, wherein the setting module is used for setting initial values of operation variables and state flag bits intelligently controlled by a delayed coking device, a feeding valve position and a threshold value of relative steam blowing quantity, and the relative steam blowing quantity refers to the ratio of steam blowing flow to feeding flow;

the acquisition and judgment module is used for acquiring a current feeding valve position value and a current steam blowing relative quantity through a distributed control system and judging a process step required to be carried out currently according to the current feeding valve position value and the current steam blowing relative quantity;

and the adjusting module is used for correspondingly adjusting the operation variables and the state flag bits according to the process steps and returning to the acquiring and judging module after the adjustment is finished.

Wherein, the obtaining and judging module comprises: and the display module is used for displaying the current process steps to be carried out after judging the current process steps to be carried out.

(III) advantageous effects

The invention realizes the intelligent compensation control of the delayed coking device and solves the technical problems that the processing of switching interference is single, the intelligent effective inhibition cannot be realized and the optimized control cannot be carried out in the switching process.

Drawings

FIG. 1 is a flow chart of a delayed coker intelligent control process in accordance with one embodiment of the present invention;

FIG. 2 is a zone profile for non-linear level control according to one embodiment of the present invention;

fig. 3 is a block diagram of a delayed coker intelligent control system in accordance with one embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

On the basis of deeply knowing a delayed coking process device and an operation flow, the influence of each stage of operation of the delayed coking device on the whole production process is extracted by analyzing field actual data, the actual experience of a field operation engineer is summarized and concluded, an expert system for influencing the bottom temperature and the liquid level of a main fractionating tower by operation events such as preheating, tower cutting, small steam blowing and the like is finally established, the inhibition on switching disturbance is realized by applying a feedforward control idea, and an iterative learning idea is introduced to search for an optimal feedforward compensation quantity in a rolling mode aiming at the characteristic of the periodic operation of delayed coking, so that the disturbance of the operation such as the switching of a delayed coking coke tower on the flow, heat, components and the like of the feeding of a downstream main fractionating tower is effectively reduced, the stable operation is finally realized, and the product quality requirement of the main fractionating tower is ensured.

The Expert System (ES) is a computer System built by a knowledge-based programming method, which integrates the knowledge and experience of experts in a certain field, and can use the knowledge like human experts to solve the complex problem that the human experts can solve by reasoning and simulating the decision making process of the human experts. The operation of the delayed coking device depends on operation experience, particularly switching operation, so that the influence of the switching operation on the whole production process can be extracted by means of analyzing actual data and the like, the actual experience of field operators is summarized and concluded, and finally an expert knowledge base and an inference machine are established to complete real-time monitoring and compensation control on the delayed coking production process.

Iterative Learning (IL) control concepts are adapted to a controlled object having repetitive motion properties, and the current control action is corrected using the previous control experience and output error of the system, so that the system output converges to a desired value as much as possible. The method has the characteristics of no model control mechanism based on memory, high learning convergence speed, strong adaptability, concise algorithm, easy use and engineering and the like.

Fig. 1 is a flow chart of a delayed coker intelligent control method according to one embodiment of the present invention, comprising the steps of:

s1: setting initial values of operating variables and status flags for delayed coker intelligent control, a feed valve position, and a threshold value of a relative amount of blown steam, the relative amount of blown steam being a ratio of a flow of blown steam to a total feed flow of a furnace, the operating variables including: the method comprises the following steps of (1) feeding flow of a main fractionating tower, upper feeding flow, middle section circulation flow, heavy wax oil downward returning flow and top circulation flow; the status flag bit includes: preheating a mark bit, a small blowing mark bit and a large blowing mark bit; the threshold values for the feed valve positions include: a normal working condition valve position threshold value, a pressure test valve position threshold value, a preheating second stage valve position threshold value, a preheating third stage valve position threshold value, a small blowing valve position threshold value and a large blowing valve position threshold value; the threshold value of the relative amount of blown steam comprises: the method comprises the steps of normal working condition steam blowing relative quantity threshold value, pressure test steam blowing relative quantity upper limit threshold value, pressure test steam blowing relative quantity lower limit threshold value, preheating steam blowing relative quantity threshold value, preheating second stage steam blowing relative quantity threshold value, preheating third stage steam blowing relative quantity threshold value, small blowing steam blowing relative quantity lower limit threshold value, small blowing steam blowing relative quantity upper limit threshold value and large blowing steam blowing relative quantity threshold value.

S2: the method comprises the following steps of obtaining a current feeding valve position value and a current blowing steam relative quantity through a distributed control system, and judging currently required process steps according to the current feeding valve position value and the current blowing steam relative quantity, wherein the process steps specifically comprise the following steps:

s201: acquiring a current feeding valve value (unit is in the embodiment) of a first coke tower, a current feeding valve value (unit is in the embodiment) of a second coke tower and a current blowing steam relative quantity through a distributed control system;

s202: judging whether to enter a 'normal working condition' process step according to the following logic relation formula (1),

[(V₁+V₂)≤CV₂]&(F_steam≤CF₂) (1)

wherein, V₁Is the current feed level value, V, of the first coke drum₂Is the current feed level value of the second coke drum, F_steamFor the current relative amount of blown steam, CV₂The valve position threshold value for the normal operation (CV in the present embodiment)₂In the range of 100 to 110 in%) CF₂Blowing a steam relative quantity threshold value for the normal working condition (in the embodiment, CF)₂In the range of 0 to 0.05 in%),&represents a logical and;

if the logical judgment result of the logical relation (1) is true, the process step of 'normal working condition' is judged to be entered, and step S3 is executed, if the logical judgment result is false, step S203 is executed;

s203: judging whether to enter a pressure test process step or not according to the following logical relation (2),

[(V₁+V₂)≤CV₃]&(CF₃₁≤F_steam≤CF₃₂) (2)

wherein, CV is₃Is the pressure test valve position threshold value (CV in the present embodiment)₃In the range of 100 to 110 in%) CF₃₁Blowing a lower relative steam amount threshold for the pressure test (in the present embodiment, CF)₃₁In the range of 0.4 to 0.5 in%) CF₃₂Blowing a steam relative quantity upper limit threshold value for the pressure test (in the embodiment, CF)₃₂In the range of 5 to 7 in%);

if the logical judgment result of the logical relation (2) is true, the process enters the "pressure test" step, and step S3 is executed, if the logical judgment result is false, step S204 is executed,

s204: judging whether to enter a preheating process step according to the following logic relation formula (3),

[(V₁+V₂)≥CV₄]&(F_steam≤CF₄) (3)

wherein, CV is₄For the preheating valve position threshold value (CV in the present embodiment)₄In the range of 100 to 110 in%) CF₄Blowing a steam relative amount threshold for the preheating (in the present embodiment, CF)₄In the range of 0 to 0.5 in%);

if the logical judgment result of the logical relation (3) is true, it is determined to enter the "preheating" process step, and step S205 is executed, and if the logical judgment result is false, step S208 is executed, where the "preheating" process step includes: the process substeps of "preheating started" and "preheating preparation";

s205: judging whether to enter a 'preheating started' process substep according to the preheating flag bit, if the preheating flag bit is true, judging to enter the 'preheating started' process substep, and executing a step S206, and if the preheating flag bit is false, judging to enter the 'preheating preparation' process substep, and executing a step S3, wherein the 'preheating started' process substep further comprises: the process substeps of a preheating first stage, a preheating second stage and a preheating third stage are carried out;

s206: judging whether to enter a 'preheating first stage' process sub-step according to the following logic relation (4),

(V₁+V₂)≥CV₆ (4)

wherein, CV is₆For the preheat second stage valve position threshold (CV in this embodiment)₆In the range of 130 to 150 in%);

if the logical judgment result of the logical relation (4) is false, the process goes into the process substep of "preheating the first stage", and step S3 is executed, if the logical judgment result is true, step S207 is executed;

s207: judging whether to enter a 'second stage of preheating' process substep according to the following logical relation (5),

(V₁+V₂)≥CV₇ (5)

wherein, CV is₇For preheating the valve position threshold value in the third stage (CV in the present embodiment)₇In the range of 195 to 200 in%);

if the logical judgment result of the logical relation (5) is false, the process substep of 'preheating the second stage' is judged to be entered, and step S3 is executed, and if the logical judgment result is true, the process substep of 'preheating the third stage' is judged to be entered, and step S3 is executed;

s208: judging whether to enter a small blowing process step according to the following logic relation formula (6),

[(V₁+V₂)≥CV₈]&(CF₈₁≤F_steam≤CF₈₂) (6)

wherein, CV is₈Is a small blow valve threshold (CV in the present embodiment)₈In the range of 195 to 200 in%) CF₈₁Blowing a lower limit threshold of the relative amount of steam for a small blow (in the present embodiment, CF)₈₁In the range of 0.4 to 0.5 in%) CF₈₂Blowing the upper limit threshold of the relative amount of steam for the small blow (in the present embodiment, CF)₈₂In the range of 4 to 5 in%);

if the logical judgment result of the logical relation (6) is true, the step is judged to enter the small air blowing process step, and the step S209 is executed, if the logical judgment result is false, the step S210 is executed, and the small air blowing process step comprises the following steps: a small air blow started process substep and a small air blow preparation process substep;

s209: judging whether a process substep of 'small air blowing is started' is entered according to the small air blowing flag bit, if the preheating flag bit is true, judging that the process substep of 'small air blowing is started' is entered, and executing a step S3, and if the preheating flag bit is false, judging that the process substep of 'small air blowing preparation' is entered, and executing a step S3;

s210: judging whether to enter a 'big blowing' process step according to the following logic relation formula (7),

[(V₁+V₂)≤CV₁₀]&(F_steam≥CF₁₀) (7)

wherein, CV is₁₀Is a large air-blowing valve position threshold value (CV in the present embodiment)₁₀In the range of 100 to 110 in%) CF₁₀Blowing a steam relative amount threshold for a large blow (in the present embodiment, CF)₁₀In the range of 4 to 5 in%);

if the logic judgment result of the logic relation (7) is true, determining to enter a 'large blowing' process step, and executing step S211, and if the logic judgment result is false, determining to enter a 'normal working condition' process step, and executing step S3, wherein the 'large blowing' process step comprises: a process substep of 'large air blowing is started' and 'large air blowing preparation';

s211: and judging whether to enter a process substep of 'large blowing is started' or not according to the large blowing flag bit, if the preheating flag bit is true, judging to enter the process substep of 'large blowing is started', and executing a step S3, and if the preheating flag bit is false, judging to enter a process substep of 'large blowing preparation', and executing a step S3.

S3: correspondingly adjusting the operation variables and the status flag bits according to the process steps, returning to the step S2 after the adjustment is finished, wherein the step S3 specifically comprises:

if the process step of 'normal working condition' is carried out, assigning the preheating flag bit, the small blowing flag bit and the large blowing flag bit as false, and carrying out non-linear liquid level control on the feeding flow of the main fractionating tower;

if the pressure test process step is carried out, assigning the preheating flag bit, the small blowing flag bit and the large blowing flag bit as false, and carrying out non-linear liquid level control on the liquid level of the main fractionating tower;

if the 'preheating preparation' process substep in the 'preheating' process step is entered, assigning the preheating flag bit to be true, assigning the small blowing flag bit and the large blowing flag bit to be false, and carrying out nonlinear liquid level control on the liquid level of the main fractionating tower;

if the preheating process sub-step in the preheating process sub-step is started and the preheating first stage process sub-step in the preheating process sub-step is in, assigning the preheating flag bit as true, assigning the small blowing flag bit and the large blowing flag bit as false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower;

if entering a preheating second stage process sub-step in the preheating process sub-step, assigning the preheating flag bit to be true, assigning the small blowing flag bit and the large blowing flag bit to be false, performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to a first adjustment quantity of the upper feeding flow, adjusting the middle section circulation flow according to a first adjustment quantity of the middle section circulation flow, adjusting the heavy wax oil lower return flow according to a first adjustment quantity of the heavy wax oil lower return flow, adjusting the top circulation flow according to a first adjustment quantity of the top circulation flow, wherein the first adjustment quantity is a preset percentage of one of the upper feeding flow, the middle section circulation flow, the heavy wax oil lower return flow and the top circulation flow, in the embodiment, the unit of all the adjustment amounts is percent, the positive value is an upward adjustment, the negative value is a downward adjustment, the initial value range of the first adjustment amount of the upward feeding flow is-5 to-1, the initial value range of the first adjustment amount of the middle section circulation flow is-10 to-3, the initial value range of the first adjustment amount of the heavy wax oil downward returning flow is 1 to 5, and the initial value range of the first adjustment amount of the top circulation flow is 0 to 1;

if entering a preheating third stage process substep in the preheating process substep, assigning the preheating flag bit to be true, assigning the small blowing flag bit and the large blowing flag bit to be false, performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to a second adjustment quantity of the upper feeding flow, adjusting the middle section circulation flow according to a second adjustment quantity of the middle section circulation flow, adjusting the heavy wax oil lower return tower flow according to a second adjustment quantity of the heavy wax oil lower return tower flow, adjusting the top circulation flow according to a second adjustment quantity of the top circulation flow, wherein the second adjustment quantity is a preset percentage of one of the upper feeding flow, the middle section circulation flow, the heavy wax oil lower return tower flow and the top circulation flow, in the embodiment, the initial value range of the second adjustment quantity of the upper feeding flow is-10 to-2, the initial value range of the second adjustment quantity of the middle section circulation flow is-15 to-6, the initial value range of the second adjustment quantity of the heavy wax oil downward returning tower flow is 2 to 10, and the initial value range of the second adjustment quantity of the top circulation flow is 0 to 2;

if the sub-step of the small blowing preparation process in the process step of small blowing is carried out, assigning the small blowing flag bit as true, assigning the preheating flag bit and the large blowing flag bit as false, and carrying out nonlinear liquid level control on the liquid level of the main fractionating tower;

if the process substep of 'small blowing' in the 'small blowing' process step is entered, assigning the small blowing flag bit to true, assigning the preheating flag bit and the large blowing flag bit to false, performing nonlinear liquid level control on the feeding flow of the main fractionating tower, adjusting the upper feeding flow according to a third adjustment quantity of the upper feeding flow, adjusting the middle section circulating flow according to a third adjustment quantity of the middle section circulating flow, adjusting the heavy wax oil lower returning flow according to a third adjustment quantity of the heavy wax oil lower returning flow, adjusting the top circulating flow according to a third adjustment quantity of the top circulating flow, wherein the third adjustment quantity is a preset percentage of one of the upper feeding flow, the circulating flow, the heavy wax oil lower returning flow and the top circulating flow, and in the embodiment, the initial value range of the third adjustment quantity of the upper feeding flow is 10-15, the initial value range of the third adjustment quantity of the middle section circulation flow is 0-1, the initial value range of the third adjustment quantity of the heavy wax oil downward returning tower flow is 3-10, and the initial value range of the third adjustment quantity of the top circulation flow is 30-70;

if the 'large blowing preparation' process substep in the 'large blowing' process step is entered, assigning the large blowing flag bit to be true, assigning the preheating flag bit and the small blowing flag bit to be false, not performing nonlinear liquid level control on the feeding flow of the main fractionating tower, respectively adjusting the adjustment quantities of the upper feeding flow, the middle section circulation flow, the heavy wax oil lower return tower flow and the top circulation flow through iterative operation according to the temperature at the bottom of the main fractionating tower, and respectively adjusting the adjustment quantities in the process of respectively adjusting the adjustment quantities, wherein the first adjustment quantity, the second adjustment quantity and the third adjustment quantity are respectively adjusted;

and if the 'large blowing gas starts' process substep in the 'large blowing gas' process step is entered, assigning the large blowing gas flag bit as true, assigning the preheating flag bit and the small blowing gas flag bit as false, and not carrying out nonlinear liquid level control on the feeding flow of the main fractionating tower.

Wherein the nonlinear liquid level control specifically comprises the steps of:

s301: the liquid level value at the bottom of the main fractionating tower is read through the distributed control system, the liquid level change rate at the bottom of the main fractionating tower is calculated according to the following relational expression (8),

VelLevel(k)＝Level(k)-Level(k-1) (8)

wherein k is a current control period (in the embodiment, the control period is 2-10 seconds), vellevel (k) is a current change rate of the liquid level at the bottom of the main fractionating tower, and level (k) is a current liquid level value at the bottom of the main fractionating tower;

s302: judging the current area according to the liquid level value at the bottom of the main fractionating tower, and dividing the current area into the following five conditions as shown in figure 2:

if the current main fractionating tower is located in the inner area, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the change rate of the liquid level at the bottom of the current main fractionating tower:

in the case that the liquid level change rate at the bottom of the main fractionating tower is larger than zero, if the following relation (9) is satisfied, the feeding flow rate of the main fractionating tower is adjusted downwards,

Level(k+T_NLC)＞HL (9)

if the following relation (10) is satisfied, the feed rate to the main fractionator is not adjusted,

Level(k+T_NLC)≤HL (10)

when the change rate of the liquid level at the bottom of the main fractionating tower is less than zero, if the following relation (11) is satisfied, the feeding flow of the main fractionating tower is not adjusted,

Level(k+T_NLC)≥LL (11)

if the following relation (12) is satisfied, the feed rate of the main fractionator is adjusted upward,

Level(k+T_NLC)＜LL (12)

in the case where the rate of change of the liquid level at the bottom of the main fractionation column is equal to zero, no adjustment is made to the feed flow to said main fractionation column.

If the current main fractionating tower is positioned in the upper outer region, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is larger than or equal to zero, the feeding flow of the main fractionating tower is adjusted downwards;

under the condition that the liquid level change rate at the bottom of the main fractionating tower is less than zero, the feeding flow of the main fractionating tower is not adjusted;

if the current main fractionating tower is in the lower outer region, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is larger than zero, the feeding flow of the main fractionating tower is not adjusted;

under the condition that the liquid level change rate at the bottom of the main fractionating tower is less than or equal to zero, the feeding flow of the main fractionating tower is adjusted upwards;

if the current position is larger than the outer upper limit area, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is larger than or equal to zero, the feeding flow of the main fractionating tower is adjusted downwards;

in the case that the rate of change of the liquid level at the bottom of the main fractionation column is less than zero, the feed rate to the main fractionation column is adjusted downward if the following relation (13) is satisfied,

Level(k+T_NLC)≥UpBd (13)

if the following relation (14) is satisfied, the feed rate to the main fractionator is not adjusted,

Level(k+T_NLC)＜UpBd (14)

and fifthly, if the current position is in a region smaller than the outer lower limit, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is less than or equal to zero, the feeding flow of the main fractionating tower is adjusted upwards;

when the liquid level change rate at the bottom of the main fractionating tower is larger than zero, if the following relation (15) is satisfied, the feeding flow rate of the main fractionating tower is not adjusted,

Level(k+T_NLC)＞LowBd (15)

if the following relation (16) is satisfied, the feed rate of the main column is adjusted upward

Level(k+T_NLC)≤LowBd (16)

In the above relational expressions (9) to (16), Level (k + T)_NLC)＝Level(k)+VelLevel(k)×T_NLCK is the current control period, VelLevel (k) is the current change rate of the liquid level at the bottom of the main fractionating tower, level (k) is the current value of the liquid level at the bottom of the main fractionating tower, T_NLCFor the prediction step length of the liquid level change, HL is a preset liquid level outer upper limit, LL is a preset liquid level outer lower limit, UpBd is a preset liquid level inner upper limit, and LowBd is a preset liquid level inner lower limit.

Wherein, the iterative learning operation specifically comprises:

sampling the temperature of the bottom of the main fractionating tower by a distributed control system, calculating the variance of the temperature of the bottom of the main fractionating tower according to the following formula (17),

<math> <mrow> <mi>D</mi> <msup> <mrow> <mo>(</mo> <mi>h</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>=</mo> <mfrac> <mn>1</mn> <mrow> <mi>n</mi> <mo>-</mo> <mn>1</mn> </mrow> </mfrac> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>0</mn> </mrow> <mi>n</mi> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>T</mi> <mi>i</mi> </msub> <mo>-</mo> <msub> <mi>T</mi> <mi>SP</mi> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>17</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein h is the current iterative learning period, D (h) is the variance of the temperature at the bottom of the main fractionating tower, n is the number of sampling points, Ti is the temperature of the ith sampling point at the bottom of the main fractionating tower, and T_SPIs the set value of the temperature at the bottom of the main fractionating tower;

the convergence factor is calculated according to the following formula (18),

<math> <mrow> <mi>&lambda;</mi> <mrow> <mo>(</mo> <mi>h</mi> <mo>)</mo> </mrow> <mo>=</mo> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <mfrac> <mn>1</mn> <mrow> <mo>|</mo> <mi>D</mi> <mrow> <mo>(</mo> <mi>h</mi> <mo>)</mo> </mrow> <mo>-</mo> <mi>D</mi> <mrow> <mo>(</mo> <mi>h</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mo>|</mo> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>18</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein λ (h) is a convergence factor;

calculating the variable quantity of each adjusting quantity of the upper feeding flow, the middle section circulation flow, the heavy wax oil downward returning tower flow and the top circulation flow in the next iterative learning period according to the following formula, wherein the variable quantity of the adjusting quantity is calculated respectively by calculating the variable quantity of a first adjusting quantity, a second adjusting quantity and a third adjusting quantity,

ΔR_MVij(h)＝λ(h){K_P[D(h)-D(h-1)]+K_ID(h)+K_D[D(h)-2D(h-1)+D(h-2)]}

-(19)

wherein MVi is the ith operating variable, i is 2, 3, 4, 5, and 2 ~ 5 operating variables correspond in proper order last feed flow, middle section circulation flow, heavy wax oil downward return tower flow and top circulation flow, R_MVij(h) J is the jth adjustment quantity of the ith operation variable, j is 1, 2, 3, and the 1 st to 3 rd adjustment quantities sequentially correspond to the first adjustment quantityAdjustment, second adjustment and third adjustment, Δ R_MVij(h) Is the variation of the jth adjustment quantity of the ith manipulated variable, K_PIs proportionally adjustable gain, K_IFor integrating the adjustable gain, K_DIs a differential adjustable gain;

calculating the adjustment quantities of the upper feeding flow, the middle section circulation flow, the heavy wax oil downward returning tower flow and the top circulation flow in the next iteration learning period according to the following formula (20),

R_MVij(h+1)＝sgn(R_MVij(h))|ΔR_MVij(h)+|R_MVij(h)|| (20)

wherein, $\mathrm{sgn}\left(R_{\mathrm{MVij}}\left(h\right)\right)=\left\{\begin{array}{c}+1,R_{\mathrm{MVij}}\left(h\right)>0\\ 0,R_{\mathrm{MVij}}\left(h\right)=0\\ -1,R_{\mathrm{MVij}}\left(h\right)<0\end{array}\right.,$

h +1 is the next iterative learning cycle.

In step S2, after the currently required process step is determined, the currently required process step is displayed.

The present invention also provides an intelligent control system for a delayed coking unit, as shown in fig. 3, comprising:

the device comprises a setting module, a control module and a control module, wherein the setting module is used for setting initial values of operation variables and state flag bits intelligently controlled by a delayed coking device, a feeding valve position and a threshold value of relative steam blowing quantity, and the relative steam blowing quantity refers to the ratio of steam blowing flow to feeding flow;

the acquisition and judgment module is used for acquiring a current feeding valve position value and a current steam blowing relative quantity through a distributed control system and judging a process step required to be carried out currently according to the current feeding valve position value and the current steam blowing relative quantity;

and the adjusting module is used for correspondingly adjusting the operation variables and the state flag bits according to the process steps and returning to the acquiring and judging module after the adjustment is finished.

The acquisition judging module comprises: and the display module is used for displaying the current process steps to be carried out after judging the current process steps to be carried out.

The above embodiments are only for illustrating the invention and are not to be construed as limiting the invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention, therefore, all equivalent technical solutions also belong to the scope of the invention, and the scope of the invention is defined by the claims.

Claims (6)

1. An intelligent control method of a delayed coking unit is characterized by comprising the following steps:

s1: setting initial values of an operating variable and a state flag bit intelligently controlled by a delayed coking unit, a feeding valve position and a threshold value of a relative blowing steam quantity, wherein the relative blowing steam quantity is a ratio of the blowing steam flow to the total feeding flow of the heating furnace;

s2: acquiring a current feeding valve position value and a current steam blowing relative quantity through a distributed control system, and judging a current process step to be carried out according to the current feeding valve position value and the current steam blowing relative quantity;

s3: correspondingly adjusting the operation variables and the state flag bits according to the process steps, and returning to the step S2 after the adjustment is finished;

wherein the operating variables include: the method comprises the following steps of (1) feeding flow of a main fractionating tower, upper feeding flow, middle section circulation flow, heavy wax oil downward returning flow and top circulation flow; the status flag bit includes: preheating a mark bit, a small blowing mark bit and a large blowing mark bit; the threshold values for the feed valve positions include: a normal working condition valve position threshold value, a pressure test valve position threshold value, a preheating second stage valve position threshold value, a preheating third stage valve position threshold value, a small blowing valve position threshold value and a large blowing valve position threshold value; the threshold value of the relative amount of blown steam comprises: the steam blowing relative quantity threshold value under the normal working condition, the pressure test steam blowing relative quantity upper limit threshold value, the pressure test steam blowing relative quantity lower limit threshold value, the preheating steam blowing relative quantity threshold value, the preheating second stage steam blowing relative quantity threshold value, the preheating third stage steam blowing relative quantity threshold value, the small blowing steam blowing relative quantity lower limit threshold value, the small blowing steam blowing relative quantity upper limit threshold value and the large blowing steam blowing relative quantity threshold value;

the step S2 specifically includes the following steps:

s201: acquiring a current feeding valve position value of a first coke tower, a current feeding valve position value of a second coke tower and a current steam blowing relative quantity through a distributed control system;

s202: judging whether to enter a 'normal working condition' process step according to the following logic relation formula (1),

[(V₁+V₂)≤CV₂]&(F_steam≤CF₂) (1)

wherein, V₁Is the current feed level value, V, of the first coke drum₂Is the current feed level value of the second coke drum, F_steamFor the current relative amount of blown steam, CV₂For said normal operating condition valve position threshold, CF₂Blowing a steam relative quantity threshold value for the normal working condition,&represents a logical and;

if the logical judgment result of the logical relation (1) is true, the process step of 'normal working condition' is judged to be entered, and step S3 is executed, if the logical judgment result is false, step S203 is executed;

s203: judging whether to enter a pressure test process step or not according to the following logical relation (2),

[(V₁+V₂)≤CV₃]&(CF₃₁≤F_steam≤CF₃₂) (2)

wherein, CV is₃For the pressure test valve position threshold, CF₃₁Blowing a lower threshold value of the relative amount of steam for the pressure test, CF₃₂Blowing a steam relative quantity upper limit threshold value for the pressure test;

if the logical judgment result of the logical relation (2) is true, the process enters the "pressure test" step, and step S3 is executed, if the logical judgment result is false, step S204 is executed,

s204: judging whether to enter a preheating process step according to the following logic relation formula (3),

[(V₁+V₂)≥CV₄]&(F_steam≤CF₄) (3)

wherein, CV is₄For said preheating valve position threshold, CF₄A relative amount threshold for the preheat blow steam;

if the logical judgment result of the logical relation (3) is true, it is determined to enter the "preheating" process step, and step S205 is executed, and if the logical judgment result is false, step S208 is executed, where the "preheating" process step includes: the process substeps of "preheating started" and "preheating preparation";

s205: judging whether to enter a 'preheating started' process substep according to the preheating flag bit, if the preheating flag bit is true, judging to enter the 'preheating started' process substep, and executing a step S206, and if the preheating flag bit is false, judging to enter the 'preheating preparation' process substep, and executing a step S3, wherein the 'preheating started' process substep further comprises: the process substeps of a preheating first stage, a preheating second stage and a preheating third stage are carried out;

s206: judging whether to enter a 'preheating first stage' process sub-step according to the following logic relation (4),

(V₁+V₂)≥CV₆ (4)

wherein, CV is₆A second stage preheating valve position threshold value;

if the logical judgment result of the logical relation (4) is false, the process goes into the process substep of "preheating the first stage", and step S3 is executed, if the logical judgment result is true, step S207 is executed;

s207: judging whether to enter a 'second stage of preheating' process substep according to the following logical relation (5),

(V₁+V₂)≥CV₇ (5)

wherein, CV is₇A valve position threshold value of the third stage of preheating;

if the logical judgment result of the logical relation (5) is false, the process substep of 'preheating the second stage' is judged to be entered, and step S3 is executed, and if the logical judgment result is true, the process substep of 'preheating the third stage' is judged to be entered, and step S3 is executed;

s208: judging whether to enter a small blowing process step according to the following logic relation formula (6),

[(V₁+V₂)≥CV₈]&(CF₈₁≤F_steam≤CF₈₂) (6)

wherein, CV is₈For a small blow valve position threshold, CF₈₁Blowing a lower threshold for the relative amount of steam for small blows, CF₈₂Blowing an upper limit threshold of the relative amount of steam for small blowing;

if the logical judgment result of the logical relation (6) is true, the step is judged to enter the small air blowing process step, and the step S209 is executed, if the logical judgment result is false, the step S210 is executed, and the small air blowing process step comprises the following steps: a small air blow started process substep and a small air blow preparation process substep;

s209: judging whether a process substep of 'small air blowing is started' is entered according to the small air blowing flag bit, if the preheating flag bit is true, judging that the process substep of 'small air blowing is started' is entered, and executing a step S3, and if the preheating flag bit is false, judging that the process substep of 'small air blowing preparation' is entered, and executing a step S3;

s210: judging whether to enter a 'big blowing' process step according to the following logic relation formula (7),

[(V₁+V₂)≤CV₁₀]&(F_steam≥CF₁₀) (7)

wherein, CV is₁₀Large blow valve position threshold, CF₁₀Blowing a steam relative quantity threshold value for large blowing;

if the logic judgment result of the logic relation (7) is true, determining to enter a 'large blowing' process step, and executing step S211, and if the logic judgment result is false, determining to enter a 'normal working condition' process step, and executing step S3, wherein the 'large blowing' process step comprises: a process substep of 'large air blowing is started' and 'large air blowing preparation';

s211: judging whether a process substep of 'large blowing is started' is entered according to the large blowing flag bit, if the preheating flag bit is true, judging that the process substep of 'large blowing is started' is entered, and executing a step S3, and if the preheating flag bit is false, judging that the process substep of 'large blowing preparation' is entered, and executing a step S3;

the step S3 specifically includes:

if the process step of 'normal working condition' is carried out, assigning the preheating flag bit, the small blowing flag bit and the large blowing flag bit as false, and carrying out non-linear liquid level control on the liquid level of the main fractionating tower;

if the pressure test process step is carried out, assigning the preheating flag bit, the small blowing flag bit and the large blowing flag bit as false, and carrying out non-linear liquid level control on the liquid level of the main fractionating tower;

if the 'preheating preparation' process substep in the 'preheating' process step is entered, assigning the preheating flag bit to be true, assigning the small blowing flag bit and the large blowing flag bit to be false, and carrying out nonlinear liquid level control on the liquid level of the main fractionating tower;

if the preheating process sub-step in the preheating process sub-step is started and the preheating first stage process sub-step in the preheating process sub-step is in, assigning the preheating flag bit as true, assigning the small blowing flag bit and the large blowing flag bit as false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower;

if entering the preheating started process sub-step in the preheating process sub-step and being in the preheating second stage process sub-step in the preheating started process sub-step, assigning the preheating flag bit to true, assigning the small blowing flag bit and the large blowing flag bit to false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to the first adjustment amount of the upper feeding flow, adjusting the middle section circulation flow according to the first adjustment amount of the middle section circulation flow, adjusting the flow of the heavy wax oil flowing down and returning to the tower according to the first adjustment quantity of the flow of the heavy wax oil flowing down and returning to the tower, adjusting the top circulating flow according to a first adjusting quantity of the top circulating flow, wherein the first adjusting quantity is a preset percentage of one of the upper feeding flow, the middle section circulating flow, the heavy wax oil downward returning flow and the top circulating flow;

if entering the preheat initiated process sub-step of the preheat initiated process sub-step and being in the preheat third stage process sub-step of the preheat initiated process sub-step, assigning the preheating flag bit to true, assigning the small blowing flag bit and the large blowing flag bit to false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to the second adjustment amount of the upper feeding flow, adjusting the middle section circulation flow according to the second adjustment amount of the middle section circulation flow, adjusting the flow of the heavy wax oil flowing down and returning to the tower according to the second adjustment quantity of the flow of the heavy wax oil flowing down and returning to the tower, adjusting the top circulating flow according to a second adjusting quantity of the top circulating flow, wherein the second adjusting quantity is a preset percentage of one of the upper feeding flow, the middle section circulating flow, the heavy wax oil downward returning flow and the top circulating flow;

if the sub-step of the small blowing preparation process in the process step of small blowing is carried out, assigning the small blowing flag bit as true, assigning the preheating flag bit and the large blowing flag bit as false, and carrying out nonlinear liquid level control on the liquid level of the main fractionating tower;

if the process substep of 'small blowing has started' in the 'small blowing' process step is entered, assigning the small blowing flag bit to true, assigning the preheating flag bit and the large blowing flag bit to false, performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to a third adjustment quantity of the upper feeding flow, adjusting the middle section circulating flow according to a third adjustment quantity of the middle section circulating flow, adjusting the heavy wax oil lower returning flow according to a third adjustment quantity of the heavy wax oil lower returning flow, and adjusting the top circulating flow according to a third adjustment quantity of the top circulating flow, wherein the third adjustment quantity is a preset percentage of one of the upper feeding flow, the middle section circulating flow, the heavy wax oil lower returning flow and the top circulating flow;

if the 'large blowing preparation' process substep in the 'large blowing' process step is entered, assigning the large blowing flag bit to be true, assigning the preheating flag bit and the small blowing flag bit to be false, performing no nonlinear liquid level control on the liquid level of the main fractionating tower, respectively adjusting the adjustment quantities of the upper feeding flow, the middle section circulation flow, the heavy wax oil lower return tower flow and the top circulation flow through iterative learning operation according to the temperature at the bottom of the main fractionating tower, and respectively adjusting the adjustment quantities in the process of respectively adjusting the adjustment quantities, wherein the first adjustment quantity, the second adjustment quantity and the third adjustment quantity are respectively adjusted;

and if the 'large blowing gas starts' process substep in the 'large blowing gas' process step is entered, assigning the large blowing gas flag bit as true, assigning the preheating flag bit and the small blowing gas flag bit as false, and performing no nonlinear liquid level control on the liquid level of the main fractionating tower.

2. The intelligent delayed coker unit control method of claim 1, wherein said non-linear level control specifically comprises the steps of:

s301: reading the liquid level value at the bottom of the main fractionating tower through the distributed control system, calculating the liquid level change rate at the bottom of the main fractionating tower according to the following relational expression (8),

VelLevel(k)＝Level(k)-Level(k-1) (8)

wherein k is the current control period, VelLevel (k) is the current change rate of the liquid level at the bottom of the main fractionating tower, and Level (k) is the current liquid level value at the bottom of the main fractionating tower;

s302: judging the current area according to the liquid level value at the bottom of the main fractionating tower, wherein the current area is divided into the following five conditions:

if the current main fractionating tower is located in the inner area, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the change rate of the liquid level at the bottom of the current main fractionating tower:

in the case that the liquid level change rate at the bottom of the main fractionating tower is larger than zero, if the following relation (9) is satisfied, the feeding flow rate of the main fractionating tower is adjusted downwards,

Level(k+T_NLC)＞HL (9)

if the following relation (10) is satisfied, the feed rate to the main fractionator is not adjusted,

Level(k+T_NLC)≤HL (10)

when the change rate of the liquid level at the bottom of the main fractionating tower is less than zero, if the following relation (11) is satisfied, the feeding flow of the main fractionating tower is not adjusted,

Level(k+T_NLC)≥LL (11)

if the following relation (12) is satisfied, the feed rate of the main fractionator is adjusted upward,

Level(k+T_NLC)＜LL (12)

under the condition that the liquid level change rate at the bottom of the main fractionating tower is equal to zero, the feeding flow of the main fractionating tower is not adjusted;

if the current main fractionating tower is positioned in the upper outer region, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is larger than or equal to zero, the feeding flow of the main fractionating tower is adjusted downwards;

under the condition that the liquid level change rate at the bottom of the main fractionating tower is less than zero, the feeding flow of the main fractionating tower is not adjusted;

if the current main fractionating tower is in the lower outer region, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is larger than zero, the feeding flow of the main fractionating tower is not adjusted;

under the condition that the liquid level change rate at the bottom of the main fractionating tower is less than or equal to zero, the feeding flow of the main fractionating tower is adjusted upwards;

if the current position is larger than the outer upper limit area, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is larger than or equal to zero, the feeding flow of the main fractionating tower is adjusted downwards;

in the case that the rate of change of the liquid level at the bottom of the main fractionation column is less than zero, the feed rate to the main fractionation column is adjusted downward if the following relation (13) is satisfied,

Level(k+T_NLC)≥UpBd (13)

if the following relation (14) is satisfied, the feed rate to the main fractionator is not adjusted,

Level(k+T_NLC)＜UpBd (14)

and fifthly, if the current position is in a region smaller than the outer lower limit, judging whether the feeding flow of the main fractionating tower needs to be adjusted according to the current liquid level change rate of the bottom of the main fractionating tower:

under the condition that the liquid level change rate at the bottom of the main fractionating tower is less than or equal to zero, the feeding flow of the main fractionating tower is adjusted upwards;

when the liquid level change rate at the bottom of the main fractionating tower is larger than zero, if the following relation (15) is satisfied, the feeding flow rate of the main fractionating tower is not adjusted,

Level(k+T_NLC)＞LowBd (15)

if the following relation (16) is satisfied, the feed rate of the main column is adjusted upward

Level(k+T_NLC)≤LowBd (16)

In the above relational expressions (9) to (16), Level (k + T)_NLC)＝Level(k)+VelLevel(k)×T_NLC，T_NLCFor the prediction step length of the liquid level change, HL is a preset liquid level outer upper limit, LL is a preset liquid level outer lower limit, UpBd is a preset liquid level inner upper limit, and LowBd is a preset liquid level inner lower limit.

3. The intelligent control method of a delayed coking unit according to claim 1, wherein the iterative learning operation is specifically:

sampling the temperature of the bottom of the main fractionating tower by a distributed control system, calculating the variance of the temperature of the bottom of the main fractionating tower according to the following formula (17),

<math> <mrow> <mi>D</mi> <msup> <mrow> <mo>(</mo> <mi>h</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>=</mo> <mfrac> <mn>1</mn> <mrow> <mi>n</mi> <mo>-</mo> <mn>1</mn> </mrow> </mfrac> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>0</mn> </mrow> <mi>n</mi> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>T</mi> <mi>i</mi> </msub> <mo>-</mo> <msub> <mi>T</mi> <mi>SP</mi> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>17</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein h is the current iterative learning period, D (h) is the variance of the bottom temperature of the main fractionating tower, n is the number of sampling points, T_iIs the temperature, T, of the ith sampling point at the bottom of the main fractionating tower_SPIs the set value of the temperature at the bottom of the main fractionating tower;

the convergence factor is calculated according to the following formula (18),

<math> <mrow> <mi>&lambda;</mi> <mrow> <mo>(</mo> <mi>h</mi> <mo>)</mo> </mrow> <mo>=</mo> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <mfrac> <mn>1</mn> <mrow> <mo>|</mo> <mi>D</mi> <mrow> <mo>(</mo> <mi>h</mi> <mo>)</mo> </mrow> <mo>-</mo> <mi>D</mi> <mrow> <mo>(</mo> <mi>h</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mo>|</mo> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>18</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein λ (h) is a convergence factor;

calculating the variation of each adjustment quantity of the upper feeding flow, the middle section circulation flow, the heavy wax oil downward returning tower flow and the top circulation flow in the next iterative learning period according to the following formula (19), wherein the variation of the adjustment quantity is calculated respectively by calculating the variation of a first adjustment quantity, a second adjustment quantity and a third adjustment quantity,

ΔR_MVij(h)＝λ(h){K_P[D(h)-D(h-1)]+K_ID(h)+K_D[D(h)-2D(h-1)+D(h-2)]}

-(19)

wherein MVi is the ith operating variable,i is 2, 3, 4, 5, 2 nd to 5 th operation variables which correspond to the upper feeding flow, the middle section circulation flow, the heavy wax oil downward returning tower flow and the top circulation flow in sequence, R_MVij(h) J is the j adjustment quantity of the ith operation variable, j is 1, 2, 3, the 1 st to 3 rd adjustment quantities correspond to the first adjustment quantity, the second adjustment quantity and the third adjustment quantity in sequence, and delta R_MVij(h) Is the variation of the jth adjustment quantity of the ith manipulated variable, K_PIs proportionally adjustable gain, K_IFor integrating the adjustable gain, K_DIs a differential adjustable gain;

calculating the adjustment quantities of the upper feeding flow, the middle section circulation flow, the heavy wax oil downward returning tower flow and the top circulation flow in the next iteration learning period according to the following formula (20),

R_MVij(h+1)＝sgn(R_MVij(h))|ΔR_MVij(h)+|R_MVij(h)|| (20)

wherein, $\mathrm{sgn}\left(R_{\mathrm{MVij}}\left(h\right)\right)=\left\{\begin{array}{c}+1,R_{\mathrm{MVij}}\left(h\right)>0\\ 0,R_{\mathrm{MVij}}\left(h\right)=0\\ -1,R_{\mathrm{MVij}}\left(h\right)<0\end{array}\right.,$

h +1 is the next iterative learning cycle.

4. The intelligent control method of a delayed coker as claimed in any one of claims 1 to 3, wherein in step S2, after the currently required process step is judged, the currently required process step is displayed.

5. A delayed coker intelligent control system, comprising:

the device comprises a setting module, a control module and a control module, wherein the setting module is used for setting initial values of operation variables and state flag bits intelligently controlled by a delayed coking device, a feeding valve position and a threshold value of relative steam blowing quantity, and the relative steam blowing quantity refers to the ratio of steam blowing flow to feeding flow;

the acquisition and judgment module is used for acquiring a current feeding valve position value and a current steam blowing relative quantity through a distributed control system and judging a process step required to be carried out currently according to the current feeding valve position value and the current steam blowing relative quantity;

the adjusting module is used for correspondingly adjusting the operation variables and the state flag bits according to the process steps and returning to the acquiring and judging module after the adjustment is finished;

wherein the operating variables include: the method comprises the following steps of (1) feeding flow of a main fractionating tower, upper feeding flow, middle section circulation flow, heavy wax oil downward returning flow and top circulation flow; the status flag bit includes: preheating a mark bit, a small blowing mark bit and a large blowing mark bit; the threshold values for the feed valve positions include: a normal working condition valve position threshold value, a pressure test valve position threshold value, a preheating second stage valve position threshold value, a preheating third stage valve position threshold value, a small blowing valve position threshold value and a large blowing valve position threshold value; the threshold value of the relative amount of blown steam comprises: the steam blowing relative quantity threshold value under the normal working condition, the pressure test steam blowing relative quantity upper limit threshold value, the pressure test steam blowing relative quantity lower limit threshold value, the preheating steam blowing relative quantity threshold value, the preheating second stage steam blowing relative quantity threshold value, the preheating third stage steam blowing relative quantity threshold value, the small blowing steam blowing relative quantity lower limit threshold value, the small blowing steam blowing relative quantity upper limit threshold value and the large blowing steam blowing relative quantity threshold value;

the acquiring and judging module specifically comprises:

the acquisition submodule is used for acquiring the current feeding valve position value of the first coke tower, the current feeding valve position value of the second coke tower and the current blowing steam relative quantity through the distributed control system;

a normal working condition judgment submodule for judging whether to enter a 'normal working condition' process step according to the following logic relation formula (1),

[(V₁+V₂)≤CV₂]&(F_steam≤CF₂) (1)

wherein, V₁Is the current feed level value, V, of the first coke drum₂Is the current feed level value of the second coke drum, F_steamFor the current relative amount of blown steam, CV₂For said normal operating condition valve position threshold, CF₂Blowing a steam relative quantity threshold value for the normal working condition,&represents a logical and;

if the logical judgment result of the logical relation (1) is true, the process step of 'normal working condition' is judged to be entered, the adjusting module is executed, and if the logical judgment result is false, the pressure test judgment sub-module is executed;

the pressure test judgment sub-module is used for judging whether to enter the pressure test process step according to the following logic relation formula (2),

[(V₁+V₂)≤CV₃]&(CF₃₁≤F_steam≤CF₃₂) (2)

wherein, CV is₃For the pressure test valve position threshold, CF₃₁For the pressure test blowingLower threshold of relative quantity of steam delivered, CF₃₂Blowing a steam relative quantity upper limit threshold value for the pressure test;

if the logic judgment result of the logic relation (2) is true, the process step of 'pressure test' is judged to be entered, the adjusting module is executed, if the logic judgment result is false, the preheating judgment sub-module is executed,

a preheating judgment submodule for judging whether to enter a preheating process step according to the following logic relation (3),

[(V₁+V₂)≥CV₄]&(F_steam≤CF₄) (3)

wherein, CV is₄For said preheating valve position threshold, CF₄A relative amount threshold for the preheat blow steam;

if the logic judgment result of the logic relation (3) is true, judging that the preheating process step is entered, executing a preheating started judgment sub-module, and if the logic judgment result is false, executing a small blowing judgment sub-module, wherein the preheating process step comprises the following steps: the process substeps of "preheating started" and "preheating preparation";

a preheating started judgment sub-module, configured to judge whether to enter a preheating started process sub-step according to the preheating flag bit, if the preheating flag bit is true, it is determined to enter the preheating started process sub-step, and execute a preheating first-stage judgment sub-module, if the preheating flag bit is false, it is determined to enter a preheating preparation process sub-step, and execute an adjustment module, where the preheating started process sub-step further includes: the process substeps of a preheating first stage, a preheating second stage and a preheating third stage are carried out;

a preheating first stage judgment submodule for judging whether to enter the 'preheating first stage' process substep according to the following logical relation (4),

(V₁+V₂)≥CV₆ (4)

wherein, CV is₆For the preheating second stage valve position threshold；

If the logic judgment result of the logic relation (4) is false, the process substep of 'preheating the first stage' is judged to enter, and the adjusting module is executed, and if the logic judgment result is true, the judgment submodule of the preheating second stage is executed;

a preheating second stage judgment submodule for judging whether to enter the 'preheating second stage' process substep according to the following logical relation (5),

(V₁+V₂)≥CV₇ (5)

wherein, CV is₇A valve position threshold value of the third stage of preheating;

if the logical judgment result of the logical relation (5) is false, the process substep of 'preheating the second stage' is judged to enter, and the adjusting module is executed, and if the logical judgment result is true, the process substep of 'preheating the third stage' is judged to enter, and the adjusting module is executed;

a small air blowing judgment submodule for judging whether to enter the small air blowing process step according to the following logic relation (6),

[(V₁+V₂)≥CV₈]&(CF₈₁≤F_steam≤CF₈₂) (6)

wherein, CV is₈For a small blow valve position threshold, CF₈₁Blowing a lower threshold for the relative amount of steam for small blows, CF₈₂Blowing an upper limit threshold of the relative amount of steam for small blowing;

if the logic judgment result of the logic relation (6) is true, judging that the small air blowing process step is entered, executing a small air blowing started judgment submodule, and if the logic judgment result is false, executing a small air blowing started judgment submodule, wherein the small air blowing process step comprises the following steps: a small air blow started process substep and a small air blow preparation process substep;

the small air blowing started judgment submodule is used for judging whether the small air blowing started process substep is entered according to the small air blowing flag bit, if the preheating flag bit is true, the small air blowing started process substep is judged to be entered, and an adjustment module is executed, and if the preheating flag bit is false, the small air blowing preparation process substep is judged to be entered, and the adjustment module is executed;

a large blowing judgment submodule for judging whether to enter a 'large blowing' process step according to the following logic relation (7),

[(V₁+V₂)≤CV₁₀]&(F_steam≥CF₁₀) (7)

wherein, CV is₁₀Large blow valve position threshold, CF₁₀Blowing a steam relative quantity threshold value for large blowing;

if the logic judgment result of the logic relation (7) is true, the step of 'large blowing' is judged to enter, the sub-module for judging whether large blowing starts is executed, if the logic judgment result is false, the step of 'normal working condition' is judged to enter, and the adjusting module is executed, wherein the step of 'large blowing' comprises the following steps: a process substep of 'large air blowing is started' and 'large air blowing preparation';

the large air blowing started judgment submodule is used for judging whether the process substep of 'large air blowing started' is entered according to the large air blowing flag bit, if the preheating flag bit is true, the process substep of 'large air blowing started' is judged to be entered, and an adjustment module is executed, and if the preheating flag bit is false, the process substep of 'large air blowing preparation' is judged to be entered, and the adjustment module is executed;

the specific adjusting mode of the adjusting module is as follows:

if the process step of 'normal working condition' is carried out, assigning the preheating flag bit, the small blowing flag bit and the large blowing flag bit as false, and carrying out non-linear liquid level control on the liquid level of the main fractionating tower;

if the pressure test process step is carried out, assigning the preheating flag bit, the small blowing flag bit and the large blowing flag bit as false, and carrying out non-linear liquid level control on the liquid level of the main fractionating tower;

if the 'preheating preparation' process substep in the 'preheating' process step is entered, assigning the preheating flag bit to be true, assigning the small blowing flag bit and the large blowing flag bit to be false, and carrying out nonlinear liquid level control on the liquid level of the main fractionating tower;

if the preheating process sub-step in the preheating process sub-step is started and the preheating first stage process sub-step in the preheating process sub-step is in, assigning the preheating flag bit as true, assigning the small blowing flag bit and the large blowing flag bit as false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower;

if entering the preheating started process sub-step in the preheating process sub-step and being in the preheating second stage process sub-step in the preheating started process sub-step, assigning the preheating flag bit to true, assigning the small blowing flag bit and the large blowing flag bit to false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to the first adjustment amount of the upper feeding flow, adjusting the middle section circulation flow according to the first adjustment amount of the middle section circulation flow, adjusting the flow of the heavy wax oil flowing down and returning to the tower according to the first adjustment quantity of the flow of the heavy wax oil flowing down and returning to the tower, adjusting the top circulating flow according to a first adjusting quantity of the top circulating flow, wherein the first adjusting quantity is a preset percentage of one of the upper feeding flow, the middle section circulating flow, the heavy wax oil downward returning flow and the top circulating flow;

if entering the preheat initiated process sub-step of the preheat initiated process sub-step and being in the preheat third stage process sub-step of the preheat initiated process sub-step, assigning the preheating flag bit to true, assigning the small blowing flag bit and the large blowing flag bit to false, and performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to the second adjustment amount of the upper feeding flow, adjusting the middle section circulation flow according to the second adjustment amount of the middle section circulation flow, adjusting the flow of the heavy wax oil flowing down and returning to the tower according to the second adjustment quantity of the flow of the heavy wax oil flowing down and returning to the tower, adjusting the top circulating flow according to a second adjusting quantity of the top circulating flow, wherein the second adjusting quantity is a preset percentage of one of the upper feeding flow, the middle section circulating flow, the heavy wax oil downward returning flow and the top circulating flow;

if the sub-step of the small blowing preparation process in the process step of small blowing is carried out, assigning the small blowing flag bit as true, assigning the preheating flag bit and the large blowing flag bit as false, and carrying out nonlinear liquid level control on the liquid level of the main fractionating tower;

if the process substep of 'small blowing has started' in the 'small blowing' process step is entered, assigning the small blowing flag bit to true, assigning the preheating flag bit and the large blowing flag bit to false, performing nonlinear liquid level control on the liquid level of the main fractionating tower, adjusting the upper feeding flow according to a third adjustment quantity of the upper feeding flow, adjusting the middle section circulating flow according to a third adjustment quantity of the middle section circulating flow, adjusting the heavy wax oil lower returning flow according to a third adjustment quantity of the heavy wax oil lower returning flow, and adjusting the top circulating flow according to a third adjustment quantity of the top circulating flow, wherein the third adjustment quantity is a preset percentage of one of the upper feeding flow, the middle section circulating flow, the heavy wax oil lower returning flow and the top circulating flow;

if the 'large blowing preparation' process substep in the 'large blowing' process step is entered, assigning the large blowing flag bit to be true, assigning the preheating flag bit and the small blowing flag bit to be false, performing no nonlinear liquid level control on the liquid level of the main fractionating tower, respectively adjusting the adjustment quantities of the upper feeding flow, the middle section circulation flow, the heavy wax oil lower return tower flow and the top circulation flow through iterative learning operation according to the temperature at the bottom of the main fractionating tower, and respectively adjusting the adjustment quantities in the process of respectively adjusting the adjustment quantities, wherein the first adjustment quantity, the second adjustment quantity and the third adjustment quantity are respectively adjusted;

and if the 'large blowing gas starts' process substep in the 'large blowing gas' process step is entered, assigning the large blowing gas flag bit as true, assigning the preheating flag bit and the small blowing gas flag bit as false, and performing no nonlinear liquid level control on the liquid level of the main fractionating tower.

6. The delayed coker intelligent control system of claim 5, wherein said acquisition decision module comprises: and the display module is used for displaying the current process steps to be carried out after judging the current process steps to be carried out.

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