Method and control system for controlling the amount of expanded air of an air separation unit

Abstract

The application discloses a control method and a control system for expansion air quantity of an air separation device, the control method comprises the following steps: S1, setting a relationship model between the expansion air quantity and the cold quantity demand, the relationship model is: F pzj =a1*F air +a2*F L +a3; S2, obtaining the data of the expansion air quantity, the total air quantity of an air compressor and the liquid yield under at least x sets of stable working conditions according to the actual operation data of the air separation device; S3, determining the values of the coefficients a1, a2 and a3 by using an ant colony algorithm. air , the liquid yield F L is substituted into the relationship model, and the expansion air quantity F pzj is calculated. According to the control method for the expansion air quantity of the air separation device, the optimal control of the expansion air quantity can be realized, the working condition is stable, the economy of the device is improved, and considerable economic benefits are generated.

Description

Technical Field

[0001] This invention relates to the field of air separation, and in particular to a method and control system for controlling the amount of expanded air in an air separation device. Background Technology

[0002] A crucial condition for the stable operation of an air separation unit is ensuring its cooling balance, and the expansion and cooling of compressed air within the expander is a key method in this process. The amount of expansion air directly affects the operating conditions of each distillation stage. If the amount of expansion air is too small, the equipment will lack sufficient cooling capacity, making it impossible to establish distillation conditions; if the amount of expansion air is too large, it will reduce the overall oxygen extraction rate of the unit, resulting in poor economic efficiency. Therefore, optimizing the control of the expansion amount in the air separation unit is of great significance for improving the stability and economy of air separation equipment.

[0003] The existing air separation unit expansion rate adjustment mainly relies on personnel experience and is adjusted according to the operating conditions. This has the following disadvantages: on the one hand, personnel adjustment is subjective and uncertain, and there is a possibility of misoperation, which may cause drastic fluctuations in operating conditions or even accidents such as unit shutdown; on the other hand, personnel experience is not enough to make the expander reach the optimal operating conditions, resulting in problems such as high energy consumption, and thus poor long-term economic efficiency. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, one objective of this invention is to propose a method for controlling the expansion air volume of an air separation device. This method achieves optimal control of the expansion air volume through an optimized ant colony algorithm, ensuring stable operation while improving the device's economic efficiency, thereby generating considerable economic benefits.

[0005] The present invention also proposes a control system for controlling the amount of expanded air using an air separation device.

[0006] A method for controlling the amount of expanded air in an air separation device according to a first aspect embodiment of the present invention includes:

[0007] Step S1, establish a relationship model between the expansion air volume and the cooling capacity requirement, wherein the relationship model is: F pzj =a1*F air +a2*F L +a3, where F pzj F represents the amount of air used for expansion. air F represents the total air volume of the air compressor. L The coefficient α1 represents the main heat exchanger's cooling loss coefficient, 0≤α1≤A1; the coefficient α2 represents the liquid cooling capacity coefficient, 0≤α2≤A2; the coefficient α3 represents the main tower's cooling loss coefficient, 0≤α3≤A3, and A1, A2, and A3 are all constants from 1 to 150.

[0008] Step S2: Based on the actual operating data of the air separator, obtain at least x sets of data on the expansion air volume, total air volume of the air compressor, and liquid production under stable operating conditions, respectively (F 1 pzj ,F 2 pzj ,F 3 pzj ...F x pzj ), (F 1 air ,F 2 air ,F 3 air ...F x air ), (F 1 L ,F 2 L ,F 3 L ...F x L ), where x is an integer greater than or equal to 3;

[0009] Step S3, using the ant colony algorithm to determine the values ​​of coefficients α1, α2, and α3, includes: dividing coefficients α1, α2, and α3 into N equal parts, with each coefficient having a discrete interval of . Let the number of ants be m, the pheromone evaporation coefficient be ρ, and the maximum number of iterations be t. max Set the pheromone level of the path [(i-1, j), (i, k)] to τ. [(i-1，j)，(i，k)] =1, where ▽α i For discrete intervals, Let α1, α2, and α3 be the upper limits of their respective ranges. Let (i-1,j) be the lower limit of the range of values ​​for α1, α2, and α3, and let (i-1,j) represent a. i The j-th discrete point or starting point of the previous coefficient, (i,k) represents the coefficient a. i The k-th discrete point, 3N≤m≤6N, 0.5≤ρ≤0.99, 50≤T max ≤150;

[0010] Step S4: If max(▽a1,▽a2,▽a3)>ε, ε≤10, then randomly obtain the probability that ant m will move from point (i-1,j) to point (i,k) at time t according to the probability formula, whereby the probability formula is: Obtained by calculating the result using the probability formula

[0011] Step S5: Substitute the data obtained in step S2, which includes at least x sets of data on expansion air volume, total air volume of the air compressor, and liquid production under stable operating conditions, into the objective function of ant m. J m For this coefficient The calculated deviation value of the actual expansion air volume;

[0012] Step S6: Update the pheromone of the ant m's transfer path in step S4:

[0013] Where Q is the pheromone constant, 1≤Q≤100;

[0014] Step S7, if J m <J best Then update the optimal solution. If J m ≥J best If so, the optimal solution will not be updated. J best ≥10 6 ;

[0015] Step S8, if the number of iterations t < t max Repeat steps S4 to S7. If t = t max Then adjust according to the following formula and

[0016] if

[0017] if

[0018] other;

[0019] Step S9, adjust the steps in step S8. and Substitute the solution into step S3, and repeat steps S3-S8 to obtain the optimal solution.

[0020] Step S10: If max(▽a1,▽a2,▽a3)≤ε, output the current optimal solution. Proceed to step S11;

[0021] Step S11, find the optimal solution Substituting into the relational model of step S1, the total air volume F of the air compressor under the current operating condition is... air Liquid production F L Substituting into the relational model, the expansion air volume F is calculated. pzj .

[0022] The method for controlling the expansion air volume of an air separation device according to an embodiment of the present invention establishes a relationship model between the expansion air volume and the cooling demand, calculates the optimal solution of coefficients using an optimized ant colony algorithm, and then further calculates the value of the expansion air volume under the current operating conditions by substituting the optimal solution of coefficients into the relationship model between the expansion air volume and the cooling demand. The method for controlling the expansion air volume of an air separation device according to the present invention automatically adjusts the air intake volume of the expander based on the load and liquid product demand, achieving optimal control of the expander, ensuring stable operating conditions, and improving the economy of the device, thereby generating considerable economic benefits.

[0023] According to some embodiments of the present invention, in step S1, constants A1, A2, and A3 are all 100.

[0024] According to some embodiments of the present invention, in step S3, the number of ants m is 4.5N and the pheromone evaporation coefficient ρ is 0.95.

[0025] According to some embodiments of the present invention, in step S2, X represents five groups, and in step S9, the formula is:

[0026]

[0027] The control system for the expansion air volume of the air separation device according to the second aspect of the present invention adopts the control method for the expansion air volume of the air separation device according to the first aspect of the present invention, which has the advantages of achieving optimal control of the expansion air volume, ensuring stable operating conditions, improving the economy of the device, and thus generating considerable economic benefits.

[0028] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0030] Figure 1 This is an optimization diagram of a method for controlling the amount of expanded air in an air separation device according to an embodiment of the present invention;

[0031] Figure 2 This is a flowchart of a method for controlling the amount of expanded air in an air separation device according to an embodiment of the present invention. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0033] The following is for reference. Figures 1-2 A method for controlling the amount of expanded air in an air separation device according to an embodiment of the present invention is described.

[0034] Step S1, establish a relationship model between the expansion air volume and the cooling capacity requirement, wherein the relationship model is: F pzj =a1*F air +a2*F L +a3, where F pzj F represents the amount of air used for expansion. air F represents the total air volume of the air compressor. L The coefficient α1 represents the main heat exchanger's cooling loss coefficient, 0≤α1≤A1; the coefficient α2 represents the liquid cooling capacity coefficient, 0≤α2≤A2; the coefficient α3 represents the main tower's cooling loss coefficient, 0≤α3≤A3, and A1, A2, and A3 are all constants from 1 to 150.

[0035] Step S2: Based on the actual operating data of the air separator, obtain at least x sets of data on the expansion air volume, total air volume of the air compressor, and liquid production under stable operating conditions, respectively (F 1 pzj ,F 2 pzj ,F 3 pzj ...F x pzj ), (F 1 air ,F 2 air ,F 3 air ...F x air ), (F 1 L ,F 2 L ,F 3 L ...F x L ), where x is an integer greater than or equal to 3;

[0036] Step S3, using the ant colony algorithm to determine the values ​​of coefficients α1, α2, and α3, includes: dividing coefficients α1, α2, and α3 into N equal parts, with each coefficient having a discrete interval of . Let the number of ants be m, the pheromone evaporation coefficient be ρ, and the maximum number of iterations be t. max Set the pheromone level of the path [(i-1, j), (i, k)] to τ. [(i-1，j)，(i，k)] =1, where ▽α i For discrete intervals, Let α1, α2, and α3 be the upper limits of their respective ranges. Let (i-1,j) be the lower limit of the range of values ​​for α1, α2, and α3, and let (i-1,j) represent a. i The j-th discrete point or starting point of the previous coefficient, (i,k) represents the coefficient a. i The k-th discrete point, 3N≤m≤6N, 0.5≤ρ≤0.99, 50≤t max ≤150;

[0037] Step S4: If max(▽a1,▽a2,▽a3)>ε, ε≤10, then randomly obtain the probability that ant m will move from point (i-1,j) to point (i,k) at time t according to the probability formula, whereby the probability formula is: Obtained by calculating the result using the probability formula

[0038] Step S5: Substitute the data obtained in step S2, which includes at least x sets of data on expansion air volume, total air volume of the air compressor, and liquid production under stable operating conditions, into the objective function of ant m. J m For this coefficient The calculated deviation value of the actual expansion air volume;

[0039] Step S6: Update the pheromone of the ant m's transfer path in step S4:

[0040] Where Q is the pheromone constant, 1≤Q≤100;

[0041] Step S7, if J m <J best Then update the optimal solution. If J m ≥J best If so, the optimal solution will not be updated. J best ≥10 6 ;

[0042] Step S8, if the number of iterations t < t max Repeat steps S4 to S7. If t = t max Then adjust according to the following formula and

[0043] if

[0044] if

[0045] other;

[0046] That is, if Then Assigned the value A i , Assigned value if Then Assigned value Assign a value of 0; if or Then Assigned value Assigned value

[0047] Step S9, adjust the steps in step S8. and Substitute the solution into step S3, and repeat steps S3-S8 to obtain the optimal solution.

[0048] Step S10: If max(▽a1,▽a2,▽a3)≤ε, output the current optimal solution. Proceed to step S11;

[0049] Step S11, find the optimal solution Substituting into the relational model of step S1, the total air volume F of the air compressor under the current operating condition is... air Liquid production F L Substituting into the relational model, the expansion air volume F is calculated. pzj .

[0050] Therefore, the method for controlling the expansion air volume of the air separation device according to an embodiment of the present invention establishes a relationship model between the expansion air volume and the cooling demand, calculates the optimal solution of coefficients using an optimized ant colony algorithm, and then further calculates the value of the expansion air volume under the current operating conditions by substituting the optimal solution of coefficients into the relationship model between the expansion air volume and the cooling demand. The method for controlling the expansion air volume of the air separation device according to the load and liquid product demand of the present invention automatically adjusts the air intake volume of the expander and achieves optimal control of the expander, ensuring stable operating conditions and improving the economy of the device, thereby generating considerable economic benefits.

[0051] The following describes a method for controlling the amount of expanded air in an air separation device according to an embodiment of the present invention, with reference to specific examples.

[0052] Step 1: Establish a model relating expansion air volume to cooling demand.

[0053] In the field of air separation, cooling capacity is mainly consumed in three aspects: cooling loss of the main heat exchanger, liquid production, and cooling loss of the main tower, as shown in formula (1).

[0054] F pzj =a1*F air +a2*F L +a3 (1)

[0055] Among them, F pzj F represents the amount of air used for expansion. air F represents the total air volume of the air compressor. L A1 represents the liquid production rate; a2 represents the main heat exchanger cooling loss coefficient, with a value range of 0 < a1 < A1; a3 represents the liquid cooling capacity coefficient, with a value range of 0 < a2 < A2; and a4 represents the main tower cooling loss coefficient, with a value range of 0 < a3 < A3. A1, A2, and A3 are constants, for example, ... Figure 1 A1, A2 and A3 all take the value 100.

[0056] Step 2: Based on the actual operating data of the air separator, obtain five sets of data on the expansion air volume, total air volume of the air compressor, and liquid output under stable operating conditions.

[0057] Step 3: Use the improved ant colony algorithm to find the optimal parameters (e.g., Figure 1 As shown), initialize the algorithm parameters: number of divisions N (e.g., N can be 15 divisions), number of ants m, volatile coefficient ρ, and maximum number of iterations t. max All are constants; for example, in this embodiment, m is 70, ρ is 0.95, and t... max Set the value to 100; discretize the coefficients a1, a2, and a3, dividing them into 15 equal parts, with the discrete interval for each coefficient being 100. Set the pheromone τ along the path [(i-1, j), (i, k)]. [(i-1，j)，(i，k)] =1;

[0058] Step 4, if The algorithm outputs the current optimal solution. Proceed to step 10; otherwise, continue with the following steps.

[0059] Step 5: Ant m randomly obtains a scheme according to the transition probability formula (2).

[0060]

[0061] Step 6: Calculate the objective function value of ant m according to formula (3).

[0062]

[0063] Step 7: Update the pheromone levels according to formula (4) for the path taken by ant m.

[0064]

[0065] Where Q is a constant.

[0066] Step 8, if J m <J best Then update the optimal solution. Otherwise, do not update the optimal solution;

[0067] Step 9: Update the iteration count t←t+1, if t<t max If so, proceed to step 5; otherwise, adjust according to formula (5). and Then proceed to step 3.

[0068]

[0069] Step 10: The relationship model between the equipment expansion air volume and cooling demand was obtained through formula (1). The total air volume F of the air compressor under the current operating conditions was then used. air Liquid production F L The accurate F can be calculated pzj The calculated value is used as the setpoint for the expansion air volume control loop, thereby achieving optimized control of the expansion volume.

[0070] This application also provides a control system for the expansion air volume of an air separation device. The control method for the expansion air volume of the air separation device according to the first aspect of the present invention has the advantages of achieving optimal control of the expansion air volume, ensuring stable operating conditions, improving the economy of the device, and thus generating considerable economic benefits.

[0071] Optionally, embodiments of this application also provide a control system for the expansion air volume of an air separation device, including a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the various processes of the control method embodiment for the expansion air volume of the air separation device described in the first aspect embodiment, and can achieve the same technical effect. To avoid repetition, they will not be described again here.

[0072] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0073] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for controlling the amount of expanded air in an air separation device, characterized in that, include: Step S1, establish a relationship model between the expansion air volume and the cooling capacity requirement, wherein the relationship model is: F pzj =a1*F air +a2*F L +a3, where F p2j F represents the amount of air used for expansion. air F represents the total air volume of the air compressor. L The coefficient α1 represents the main heat exchanger's cooling loss coefficient, 0≤α1≤A1; the coefficient α2 represents the liquid cooling capacity coefficient, 0≤α2≤A2; the coefficient α3 represents the main tower's cooling loss coefficient, 0≤α3≤A3, and A1, A2, and A3 are all constants from 1 to 150. Step S2: Based on the actual operating data of the air separator, obtain at least x sets of data on the expansion air volume, total air volume of the air compressor, and liquid production under stable operating conditions, respectively (F 1 pzj F 2 pzj F 3 pzj ...F x pzj ), (F 1 air F 2 air F 3 air ...F x air ), (F 1 L F 2 L F 3 L ...F X L ), where x is an integer greater than or equal to 3; Step S3, using the ant colony algorithm to determine the values ​​of coefficients α1, α2, and α3, includes: dividing coefficients α1, α2, and α3 into N equal parts, with each coefficient having a discrete interval of . Let the number of ants be m, the pheromone evaporation coefficient be ρ, and the maximum number of iterations be t. max Set the pheromone level of the path [(i-1, j), (i, k)] to τ. [(i-1，j)，(i，k) ] = 1, where, α i For discrete intervals, Let α1, α2, and α3 be the upper limits of their respective ranges. Let (i-1, j) be the lower limit of the range of values ​​for α1, α2, and α3, and let (i-1, j) represent a. i The j-th discrete point or starting point of the previous coefficient, (i, k) represents the coefficient a. i The k-th discrete point, 3N≤m≤6N, 0.5≤ρ≤0.99, 50≤t max ≤150; Step S4, if If ε≤10, then the probability of ant m moving from point (i-1, j) to point (i, k) at time t is randomly obtained according to the probability formula, which is: Obtained by calculating the result using the probability formula Step S5: Substitute the data obtained in step S2, which includes at least x sets of data on expansion air volume, total air volume of the air compressor, and liquid production under stable operating conditions, into the objective function of ant m. J m For this coefficient The calculated deviation value of the actual expansion air volume; Step S6: Update the pheromone of the ant m's transfer path in step S4: Where Q is the pheromone constant, 1≤Q≤100; Step S7, if J m <J best Then update the optimal solution. If J m ≥J best If so, the optimal solution will not be updated. J best ≥10 6 ; Step S8, if the number of iterations t < t max Repeat steps S4 to S7. If t = t max Then adjust according to the following formula and if if other; Step S9, adjust the steps in step S8. and Substitute the solution into step S3, and repeat steps S3-S8 to obtain the optimal solution. Step S10, if Output the current optimal solution Proceed to step S11; Step S11, find the optimal solution Substituting into the relational model of step S1, the total air volume F of the air compressor under the current operating condition is... air Liquid production F L Substituting into the relational model, the expansion air volume F is calculated. pzj .

2. The method for controlling the amount of expanded air in the air separation device according to claim 1, characterized in that, In step S1, constants A1, A2, and A3 are all 100.

3. The method for controlling the amount of expanded air in the air separation device according to claim 1, characterized in that, In step S3, the number of ants is m = 4.5N, and the pheromone evaporation coefficient ρ is 0.

95.

4. The method for controlling the amount of expanded air in the air separation device according to claim 1, characterized in that, In steps S4 and S10, 5. The method for controlling the amount of expanded air in the air separation device according to claim 1, characterized in that, In step S2, X represents five groups, and the formula in step S9 is:

6. A control system for the amount of expanded air in an air separation device, characterized in that, The method for controlling the amount of expanded air in the air separation device according to any one of claims 1-4.

7. A control system for the amount of expanded air in an air separation device, comprising a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein the program or instructions, when executed by the processor, implement the control method as described in any one of claims 1-5.

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