Method for optimizing parameters of marine circulating cooling water system based on multi-objective decision

Abstract

The present application relates to a method for optimizing parameters of a marine closed cooling water system based on multi-objective decision-making. The method comprises the following steps: obtaining the attribute parameters of the cooling medium and the heat exchange equipment, grasping the system parameters of the cooled medium, setting the boundary conditions of the primary and secondary heat exchange temperature differences, and inputting these parameters into an optimization model of the closed cooling water system; generating all parameter combination schemes that meet the constraint conditions through the exhaustion method; further classifying and descendingly sorting the schemes according to the same primary heat exchange flow, respectively selecting the primary and secondary heat exchange flows and the total heat exchange area as different decision-making objectives for hierarchical optimization and screening to obtain an optimized scheme of multi-parameter combination; further setting the primary heat exchange flow value percentage increase ⊿Q f % and the secondary heat exchange flow value percentage increase ⊿Q s % or the primary and secondary heat exchange temperature differences to obtain an optimal scheme of multi-parameter combination, so as to realize the dual objectives of cost reduction and energy saving of the marine closed cooling water system.

Description

Technical Field

[0001] This invention relates to the field of marine closed-loop cooling water, and more specifically to a method for optimizing the parameters of marine circulating cooling water systems based on multi-objective decision-making. Background Technology

[0002] Offshore circulating cooling water systems provide cooling and heat exchange for large compressors and coolers, removing the heat generated during natural gas compression to ensure the normal operation of machinery and provide crucial support for production. Offshore closed-loop cooling water systems are essential for offshore oil and gas field development. To conserve precious freshwater resources, a common approach is to use freshwater to cool the process flow as the primary cooling heat exchanger, followed by seawater cooling the freshwater as the secondary cooling heat exchanger.

[0003] The marine circulating cooling water system involves multiple parameters, including the inlet and outlet temperatures of the primary heat exchanger's cold and heat sources (4 temperatures each), the inlet and outlet temperatures of the secondary heat exchanger's cold and heat sources (4 temperatures each), the heat exchange temperature difference between the primary and secondary heat exchanger's cold and heat flows, the logarithmic mean temperature difference between the primary and secondary heat exchanger equipment, the primary heat exchange flow rate, the secondary heat exchange flow rate, the primary heat exchange area, the secondary heat exchange area, and the total area. The selection of direct temperature parameters in the primary and secondary heat exchange processes will affect multiple indirect temperature parameters and the cascading changes in related system parameters. These cascading changes have a decisive impact on the system's scale and energy-saving performance.

[0004] When a co-current heat exchanger is used for primary heat exchange, the larger the temperature difference, the lower the system flow rate, and the larger the heat exchange area. Under practical conditions, engineering projects typically prioritize finding a larger temperature difference between the primary and secondary heat exchangers to reduce system flow rate, thus weakening the influence of heat exchange area on temperature selection. Furthermore, there is a temperature distribution factor between primary and secondary heat exchangers, resulting in uneven distribution of the temperature difference between the primary heat source and the secondary cold source, often leading to solutions deviating from the overall optimal solution. Therefore, optimizing system parameters is crucial for achieving energy savings and comprehensive engineering benefits. Moreover, when a fixed value is determined for the primary or secondary heat exchange temperature difference, various temperature combinations exist, making it difficult to quickly and intuitively select the optimal solution that meets the conditions in engineering projects. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a parameter optimization method for marine circulating cooling water systems based on multi-objective decision-making. This method couples multiple parameters such as flow rate, temperature difference, and area in heat exchange and uses a multi-objective decision-making approach to derive the optimal solution that meets the given conditions. This method, leveraging computer tools, can quickly determine, analyze, and provide the optimal combination of multiple parameters. Furthermore, it can simultaneously achieve the dual objectives of cost reduction and efficiency improvement, as well as energy conservation, thereby reducing investment while lowering carbon emissions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A parameter optimization method for offshore circulating cooling water systems based on multi-objective decision-making aims to improve the parameter selection method for offshore circulating cooling water systems in offshore oil and gas fields and to quickly obtain optimization conclusions. It couples multiple heat exchange parameters and uses computer tools to quickly determine and screen the optimal combination that meets the conditions.

[0008] A parameter optimization method for offshore circulating cooling water systems based on multi-objective decision-making includes:

[0009] Obtain the attribute parameters and input them into the optimization model of the marine circulating cooling water system;

[0010] Obtain system parameters and input them into the marine circulating cooling water system optimization model;

[0011] The boundary parameters of the heat exchange temperature difference are obtained by setting the boundary condition interval parameters for the primary and secondary heat exchange temperature differences, and these boundary parameters are then input into the optimization model of the marine circulating cooling water system; and

[0012] Based on attribute parameters, system parameters, and boundary parameters, all parameter combination schemes that meet the constraints are generated through an exhaustive method. These schemes are categorized and sorted in descending order according to the same primary heat exchange flow rate. The optimal selection steps include: identifying the total heat exchange area value from groups with the same primary and secondary heat exchange flow rates, and extracting groups with a total heat exchange area smaller than this value; identifying the total heat exchange area value from groups with the same primary heat exchange flow rate and the smallest secondary heat exchange flow rate, and extracting groups with a total heat exchange area smaller than this value; identifying the secondary heat exchange flow rate value from groups with the same primary heat exchange flow rate and the smallest total heat exchange area, and extracting groups with a secondary heat exchange flow rate smaller than this value; identifying the total heat exchange area value from groups with the same secondary heat exchange flow rate and the smallest primary heat exchange flow rate, and extracting groups with a total heat exchange area smaller than this value; identifying the secondary heat exchange flow rate and total heat exchange area value from the group with the smallest primary heat exchange flow rate, and extracting groups from other groups with a secondary heat exchange flow rate smaller than or equal to this total heat exchange area, to obtain all optimized combinations within the optimal range of total heat exchange area; and setting a percentage increase in primary heat exchange flow rate ΔQ. f % and the percentage increase in secondary heat exchange flow rate ⊿Q sThe percentage or the temperature difference between the primary and secondary heat exchangers is used to obtain the optimal solution with multiple parameter combinations.

[0013] The acquisition of attribute parameters includes: under predetermined heat exchange conditions, acquiring the attribute parameters of the cooling medium and the attribute parameters of the heat exchange equipment. The attribute parameters of the cooling medium and the attribute parameters of the heat exchange equipment include the specific heat of the primary heat exchange cold source medium, the specific heat of the secondary heat exchange cold source medium, the heat transfer coefficient of the primary heat exchange equipment, the heat transfer coefficient of the secondary heat exchange equipment, the primary thermal efficiency coefficient, the secondary thermal efficiency coefficient, the primary flow rate coefficient, and the secondary flow rate coefficient.

[0014] The system parameters are obtained as follows: the parameters of the cooled medium are obtained from the process system simulation results. The parameters of the cooled medium include the inlet and outlet temperatures of the primary heat exchange heat source, the cooling load of the primary heat exchange and the cooling load of the secondary heat exchange. The parameter combinations include: the inlet temperature of the primary heat exchange cold source, the outlet temperature of the primary heat exchange cold source, the temperature difference of the primary heat exchange, the temperature difference of the secondary heat exchange, the flow rate of the primary heat exchange, the flow rate of the secondary heat exchange, the heat exchange area of ​​the primary heat exchange equipment, the heat exchange area of ​​the secondary heat exchange equipment and the total heat exchange area.

[0015] When the heat exchange is a co-current flow, determine the relative values ​​of T1-t1 and T2-t2; the higher value is Δt. max Otherwise, it is Δt min When the heat exchange is counter-current, determine the relative values ​​of T1-t2 and T2-t1; the higher value is Δt. max Otherwise, it is Δt min The secondary heat exchange is set to counter-current, and the time interval t2-t is determined. b With t1-t a The higher or lower, the greater is Δt. max Otherwise, it is Δt min ;

[0016] Determine Δt max With Δt min The ratio,

[0017] when When, then set the objective function Δt m for:

[0018]

[0019] when When, then set the objective function Δt m for:

[0020]

[0021] In the formula

[0022] T1 is the inlet temperature of the primary heat exchanger;

[0023] T2 is the outlet temperature of the primary heat exchanger heat source;

[0024] t1 is the inlet temperature of the primary heat exchange cold source;

[0025] t2 is the outlet temperature of the primary heat exchange cold source;

[0026] t a This refers to the inlet temperature of the secondary heat exchange cold source.

[0027] t b This refers to the outlet temperature of the secondary heat exchange cold source.

[0028] Objective function Δt m This is the logarithmic mean temperature difference for a single heat exchange or the logarithmic mean temperature difference for a two-stage heat exchange.

[0029] Δt mf The logarithmic mean temperature difference for a single heat exchange;

[0030] Δt ms The logarithmic mean temperature difference for secondary heat exchange;

[0031] The obtained Δt m The results are used to output the heat exchange area of ​​a primary heat exchanger or a secondary heat exchanger.

[0032] The objective function is:

[0033] min Q f (Q f1 Q f2 , ...Q fn )

[0034] min Q s (Q s1 Q s2 , ...Q sn )

[0035] maxΔt m f (Δt m f1 , Δt m f2 ,…Δt m fn )

[0036] maxΔt m s (Δt m s1 , Δt m s2 ,…Δt m sn )

[0037] min A f (A f1 A f2 , ...A fn )

[0038] min A s (A s1 A s2 , ...Asn )

[0039] min A(A1, A2, ..., A n )

[0040] The constraints are:

[0041] When the heat exchange is a co-current flow, t2 ≤ T2-3, t2 = t1 + Δt f ;

[0042] When the heat exchange is counter-current, t2 ≤ T1-3 and t1 ≤ T2-3, t2 = t1 + Δt f ;

[0043] The secondary heat exchange is set to counter-current, t a ≤t1-3 and t b ≤t2-3,t b =t a +Δt s ;

[0044] In the formula

[0045] Q f This is the heat exchange flow rate for one heat exchange.

[0046] Q s This refers to the secondary heat exchange flow rate;

[0047] A f The heat exchange area of ​​a primary heat exchanger;

[0048] A s The heat exchange area of ​​the secondary heat exchange equipment;

[0049] A represents the total heat exchange area;

[0050] Δt f This refers to the temperature difference during a single heat exchange.

[0051] Δt s This refers to the temperature difference during secondary heat exchange.

[0052] Extract groups with the same primary heat exchange flow rate from groups with the same secondary heat exchange flow rate, retain the group with the smallest total heat exchange area, and exclude the remaining groups.

[0053] Extract the group with the smallest secondary heat exchange flow rate from the groups with the same primary heat exchange flow rate, and use the corresponding total heat exchange area in this group as the benchmark total heat exchange area. Retain the groups with the same primary heat exchange flow rate whose total heat exchange area is less than the benchmark total heat exchange area.

[0054] Extract the group with the smallest total heat exchange area from the groups with the same primary heat exchange flow rate. Use the corresponding secondary heat exchange flow rate in this group as the benchmark secondary heat exchange flow rate. Retain the groups with the same primary heat exchange flow rate whose secondary heat exchange flow rate is smaller than the benchmark secondary heat exchange flow rate.

[0055] Extract the group with the smallest primary heat exchange flow rate from the groups with the same secondary heat exchange flow rate, and use the corresponding total heat exchange area in this group as the benchmark total heat exchange area. Then, retain the groups with the same secondary heat exchange flow rate whose total heat exchange area is smaller than the benchmark total heat exchange area.

[0056] Extract the group with the minimum primary heat exchange flow rate from the group with the minimum secondary heat exchange flow rate. Use the corresponding secondary heat exchange flow rate and total heat exchange area in this group as the benchmark secondary heat exchange flow rate and benchmark total heat exchange area. Retain the groups whose secondary heat exchange flow rate is smaller than the benchmark secondary heat exchange flow rate in the groups whose primary heat exchange flow rate is not the minimum. Also retain the groups whose total heat exchange area is smaller than the benchmark total heat exchange area in the groups whose primary heat exchange flow rate is not the minimum. This will give you all the optimized combinations of the optimal range of total heat exchange area.

[0057] Set the percentage increase in primary heat exchange flow rate ⊿Q f % and the percentage increase in secondary heat exchange flow rate ⊿Q s Alternatively, by locking the primary heat exchange temperature difference and the secondary heat exchange temperature difference, a unique optimal combination of the primary heat exchange cold source inlet temperature, the primary heat exchange cold source outlet temperature, the primary heat exchange flow rate, the primary heat exchange area, the secondary heat exchange flow rate, the secondary heat exchange area, and the total heat exchange area can be obtained.

[0058] The present invention has the following advantages due to the adoption of the above technical solutions:

[0059] 1. This invention uses the exhaustive results that meet the judgment conditions to perform multi-objective decision-making to obtain the optimal combination of system parameters, avoiding the one-sidedness caused by selecting any parameter combination that meets the constraints, or the situation where only one or two parameters are focused on to seek the optimal, which leads to the system deviating from the overall optimality.

[0060] 2. This invention does not rely on a single parameter as the determining factor. Depending on the actual situation, any parameter can be selected as a limiting factor to determine the optimal solution, making the system optimization more flexible and practical.

[0061] 3. This invention takes the principle of comprehensive optimization of flow rate and area as the basis, so that the system solution can reduce energy consumption and make intensive use of space. It can simultaneously achieve the dual goals of reducing engineering costs and increasing efficiency and saving energy, thereby reducing investment and carbon emissions at the same time.

[0062] 4. This invention, with the help of computer tools, can quickly determine, analyze and provide the optimal combination of multiple parameters, which greatly improves production efficiency and intensification. Attached Figure Description

[0063] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0064] Figure 1 This is a schematic diagram of the overall process according to an embodiment of this application. Detailed Implementation

[0065] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0066] To achieve the above objectives, the present invention employs the following technical methods:

[0067] A parameter optimization method for a marine circulating cooling water system based on multi-objective decision-making includes the following steps:

[0068] Obtain attribute parameters: Under specific heat exchange conditions, obtain the attribute parameters of the cooling medium and the heat exchange equipment, and input these parameters into the optimization model of the marine circulating cooling water system.

[0069] This includes the specific heat C of the primary heat exchange cold source medium. f Specific heat C of the secondary heat exchanger cold source medium s The heat transfer coefficient K of a primary heat exchanger f The heat transfer coefficient K of the secondary heat exchange equipment s Primary thermal efficiency coefficient ε f Secondary thermal efficiency coefficient ε s Primary flow coefficient ξ f Secondary flow coefficient ξ s ;

[0070] Obtain system parameters: Obtain the parameters of the cooled medium from the process system simulation results and input these parameters into the marine circulating cooling water system optimization model.

[0071] This includes the inlet temperature T1 and outlet temperature T2 of the primary heat exchanger, and the primary heat exchanger cooling load W. f Secondary heat exchange cooling load W s ;

[0072] Set boundary parameters: Set the primary heat exchange temperature difference Δt fand secondary heat exchange temperature difference Δt s The boundary conditions are within a reasonable range, and this range is input into the optimization model of the marine circulating cooling water system;

[0073] Based on the obtained attribute parameters, system parameters, and set boundary parameters, all parameter combinations (CASE1, CASE2, ... CASEn) that meet the constraints are generated using an exhaustive method, and then according to Q... f Group the same groups together, and follow the order of Q. f Sort in descending order. Each combination scheme includes the inlet temperature t1 of the primary heat exchange cold source, the outlet temperature t2 of the primary heat exchange cold source, and the primary heat exchange temperature difference Δt. f Secondary heat exchange temperature difference Δt s Primary heat exchange flow rate Q f Secondary heat exchange flow rate Q s Heat exchange area A of primary heat exchange equipment f The heat exchange area A of the secondary heat exchange equipment s Total heat exchange area A;

[0074] The method also includes the following steps:

[0075] When the heat exchange is a co-current flow, determine the relative values ​​of T1-t1 and T2-t2; the higher value is Δt. max Otherwise, it is Δt min When the heat exchange is counter-current, determine the relative values ​​of T1-t2 and T2-t1; the higher value is Δt. max Otherwise, it is Δt min The secondary heat exchange is set to counter-current, and the time interval t2-t is determined. b With t1-t a The higher or lower, the greater is Δt. max Otherwise, it is Δt min ;

[0076] Then, determine Δt max With Δt min The ratio. When When, then set the objective function Δt m for:

[0077]

[0078] when When, then set the objective function Δt m for:

[0079]

[0080] In the formula t a t represents the inlet temperature of the secondary heat exchange cold source. bThe outlet temperature of the secondary heat exchange cold source; the objective function Δt m Δt is a general term for the logarithmic mean temperature difference of a single heat exchange or the logarithmic mean temperature difference of a two-stage heat exchange. The Δt calculated from the results of the determination of the four parameters T1, T2, t1, and t2 is... m Then, it is the logarithmic mean temperature difference Δt for a single heat exchange. m f The terms t1, t2, and t a t b Δt calculated from the results of the four parameter determinations m Then, the logarithmic mean temperature difference Δt in the secondary heat exchange is... m s .

[0081] The obtained Δt m The result is used to output A. f Or A s ;

[0082] The method also includes the following steps:

[0083] Objective function:

[0084] min Q f (Q f1 Q f2 , ...Q fn )

[0085] min Q s (Q s1 Q s2 , ...Q sn )

[0086] maxΔt mf (Δt m f1 , Δt m f2 ,…Δt m fn )

[0087] maxΔt m s (Δt m s1 , Δt m s2 ,…Δt m sn )

[0088] min A f (A f1 A f2 , ...A fn )

[0089] min A s (A s1 A s2 , ...A sn )

[0090] min A(A1, A2, ..., A n )

[0091] Constraints:

[0092] When the heat exchange is a co-current flow, t2 ≤ T2-3, t2 = t1 + Δt f ;

[0093] When the heat exchange is counter-current, t2 ≤ T1-3 and t1 ≤ T2-3, t2 = t1 + Δt f ;

[0094] The secondary heat exchange is set to counter-current, t a ≤t1-3 and t b ≤t2-3,t b =t a +Δt s ;

[0095] From Q f Extract Q from the same group s Same group (Q) f Q s1 Q s2 , ...Q sn ), and retain the group with the smallest total heat exchange area A, and exclude the rest;

[0096] From Q f Extract Q from the same group s The smallest group (Q) f Q s min Using the corresponding A value in this group as the benchmark, retain Q. f In the same group, A n Groups whose values ​​are smaller than this benchmark A value (Q) f A n <A);

[0097] From Q f Extract the group with the smallest A from the same groups (Q) f A min ), with the corresponding Q in this group s The value is the baseline, retaining Q. f Q in the same group sn The value is greater than this benchmark Q. s The group with smaller value (Q) f Q sn <Q s );

[0098] From Q s Extract Q from the same group f The smallest group (Q) s Q f min Using the corresponding A value in this group as a benchmark, retain Q. s In the same group, A n Groups whose values ​​are smaller than this benchmark A value (Q) sA n <A);

[0099] Extract Q f Q in the smallest group s The group with the minimum value, with the corresponding Q in this group s And A is the benchmark (Q) f min Q smin Q s And A), keep Q f Q in a non-minimum group sn Value compared to benchmark Q s The group with the smaller value also retains Q. f In the group A of the non-minimum group n Groups whose values ​​are smaller than the baseline A value (Q) f Q sn <Q s Or A n <A); This step yields all optimized combinations of intervals with the optimal total area;

[0100] The above steps yield a system optimization scheme with the optimal parameter combination. The scheme includes setting the percentage increase in primary heat exchange flow rate ΔQ based on actual engineering conditions. f % and the percentage increase in secondary heat exchange flow rate ΔQ s % value or lock the primary heat exchange temperature difference Δt f and the secondary heat exchange temperature difference Δt s At that time, we obtain t1, t2, and Q. f A f Q s A s The optimal combination of A and B.

[0101] like Figure 1 As shown, according to some embodiments of this application, a method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making includes inputting attribute parameters, system parameters, and constraints, determining boundary conditions, and judging Δt for primary co-current heat transfer. max With Δt min Whether the ratio is greater than or equal to 2 is used to determine Δt in a single countercurrent heat transfer. max With Δt min Whether the ratio is greater than or equal to 2 is used to determine the Δt value for secondary countercurrent heat transfer. max With Δt min Whether the ratio is greater than or equal to 2, if the judgment is "yes", the logarithmic mean temperature difference formula is used for calculation; if the judgment is "no", the mean temperature difference formula is used for calculation. All parameter combination schemes are generated by exhaustive method, and Q is extracted. f Q s Identify the group with the smallest A among the same groups, and then identify Q. f Same, Q sExtract the A value from the smallest group and Q. f In the same group, identify groups where An is less than A; identify Q. f Same, Q in the A group s Value, extract Q f Q in the same group sn Less than Q s The group; Identify Q s Same, Q f Extract the A value from the smallest group and Q. s In the same group, identify groups where An is less than A; identify Q. f Q of the smallest group s Minimum value of Q s And A value, extract Q from other groups sn Less than Q s For groups where An is less than A, multiple optimal solutions with a single optimal parameter are obtained. These solutions are then locked or set to obtain the optimal solution with the most parameters.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A parameter optimization method for a marine circulating cooling water system based on multi-objective decision-making, characterized in that, include: Obtain the attribute parameters and input them into the optimization model of the marine circulating cooling water system; Obtain system parameters and input them into the optimization model of the marine circulating cooling water system; The boundary parameters of the heat exchange temperature difference are obtained by setting the boundary condition interval parameters of the primary heat exchange temperature difference and the secondary heat exchange temperature difference, and the boundary parameters are input into the optimization model of the marine circulating cooling water system. and Based on the attribute parameters, system parameters, and boundary parameters, all parameter combination schemes that meet the constraints are generated through an exhaustive method. These schemes are then categorized and sorted in descending order according to the same primary heat exchange flow rate. The optimal scheme with multiple parameter combinations is selected, including: Identify the total heat exchange area value from groups with the same primary heat exchange flow rate and the same secondary heat exchange flow rate, and extract groups with a total heat exchange area smaller than this value. From groups with the same primary heat exchange flow rate and the smallest secondary heat exchange flow rate, identify the total heat exchange area value and extract groups smaller than this total heat exchange area; from groups with the same primary heat exchange flow rate and the smallest total heat exchange area, identify the secondary heat exchange flow rate value and extract groups smaller than this secondary heat exchange flow rate value; from groups with the same secondary heat exchange flow rate and the smallest primary heat exchange flow rate, identify the total heat exchange area value and extract groups smaller than this total heat exchange area; from groups with the smallest secondary heat exchange flow rate in the group with the smallest primary heat exchange flow rate, identify both the secondary heat exchange flow rate and the total heat exchange area value, and extract groups from other groups that are smaller than either the secondary heat exchange flow rate or the total heat exchange area, to obtain all optimized combinations of the optimal range for the total heat exchange area; set the primary heat exchange flow rate increment percentage ΔQ. f % and the percentage increase in secondary heat exchange flow rate ⊿Q s The percentage or the temperature difference between the primary and secondary heat exchangers is used to obtain the optimal solution with multiple parameter combinations.

2. The method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making according to claim 1, characterized in that, The acquisition of attribute parameters includes: under predetermined heat exchange conditions, acquiring cooling medium attribute parameters and heat exchange equipment attribute parameters, wherein the cooling medium attribute parameters and heat exchange equipment attribute parameters include specific heat of primary heat exchange cold source medium, specific heat of secondary heat exchange cold source medium, heat transfer coefficient of primary heat exchange equipment, heat transfer coefficient of secondary heat exchange equipment, primary thermal efficiency coefficient, secondary thermal efficiency coefficient, primary flow coefficient, and secondary flow coefficient. The acquisition of system parameters includes: obtaining the parameters of the cooled medium from the process system simulation results. The parameters of the cooled medium include the inlet and outlet temperatures of the primary heat exchange heat source, the primary heat exchange cooling load, and the secondary heat exchange cooling load. The parameter combination includes: the inlet temperature of the primary heat exchange cold source, the outlet temperature of the primary heat exchange cold source, the primary heat exchange temperature difference, the secondary heat exchange temperature difference, the primary heat exchange flow rate, the secondary heat exchange flow rate, the heat exchange area of ​​the primary heat exchange equipment, the heat exchange area of ​​the secondary heat exchange equipment, and the total heat exchange area.

3. The method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making according to claim 1, characterized in that, When the heat exchange is a co-current flow, determine the relative values ​​of T1-t1 and T2-t2; the higher value is Δt. max Otherwise, it is Δt min When the heat exchange is counter-current, determine the relative values ​​of T1-t2 and T2-t1; the higher value is Δt. max Otherwise, it is Δt min When the secondary heat exchange is set to counter-flow, determine t2-t. b With t1-t a The higher or lower, the greater is Δt. max Otherwise, it is Δt min ; Determine Δt max With Δt min The ratio: when When, then set the objective function Δt m for: when When, then set the objective function Δt m for: In the formula: T1 is the inlet temperature of the primary heat exchanger; T2 is the outlet temperature of the primary heat exchanger heat source; t1 is the inlet temperature of the primary heat exchange cold source; t2 is the outlet temperature of the primary heat exchange cold source; t a This refers to the inlet temperature of the secondary heat exchange cold source. t b This refers to the outlet temperature of the secondary heat exchange cold source. Objective function Δt m This is the logarithmic mean temperature difference for a single heat exchange or the logarithmic mean temperature difference for a two-stage heat exchange. Δt mf The logarithmic mean temperature difference for a single heat exchange; Δt ms The logarithmic mean temperature difference for secondary heat exchange; The obtained objective function Δt m The results are used to output the heat exchange area of ​​a primary heat exchanger or a secondary heat exchanger.

4. The method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making according to claim 3, characterized in that, The objective function is: min Q f (Q f1 ,Q f2 ,…Q fn ) min Q s (Q s1 ,Q s2 ,…Q sn ) maxΔt mf (Δt mf1 ,Δt mf2 ,…Δt mfn ) maxΔt ms (Δt ms1 ,Δt ms2 ,…Δt msn ) for me f (IN f1 ,IN f2 ,…IN fn ) for me s (IN s1 ,IN s2 ,…IN sn ) min A(A1, A2, …A n ) The constraints are: When the heat exchange is a co-current flow, t2 ≤ T2-3, t2 = t1 + Δt f ; When the heat exchange is counter-current, t2 ≤ T1-3 and t1 ≤ T2-3, t2 = t1 + Δt f ; The secondary heat exchange is set to counter-current, t a ≤t1-3 and t b ≤t2-3,t b =t a +⊿t s ; In the formula: Q f This is the heat exchange flow rate for one heat exchange. Q s This refers to the secondary heat exchange flow rate; A f The heat exchange area of ​​a primary heat exchanger; A s The heat exchange area of ​​the secondary heat exchange equipment; A represents the total heat exchange area; ⊿t f This refers to the temperature difference during a single heat exchange. ⊿t s This refers to the temperature difference during secondary heat exchange.

5. The method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making according to claim 1, characterized in that, Extract groups with the same primary heat exchange flow rate from groups with the same secondary heat exchange flow rate, retain the group with the smallest total heat exchange area, and exclude the remaining groups.

6. The method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making according to claim 5, characterized in that, Extract the group with the smallest secondary heat exchange flow rate from the groups with the same primary heat exchange flow rate, and use the corresponding total heat exchange area in this group as the benchmark total heat exchange area. Then retain the groups with the same primary heat exchange flow rate whose total heat exchange area is less than the benchmark total heat exchange area.

7. The method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making according to claim 6, characterized in that, Extract the group with the smallest total heat exchange area from the groups with the same primary heat exchange flow rate. Use the corresponding secondary heat exchange flow rate in this group as the benchmark secondary heat exchange flow rate. Retain the groups with the same primary heat exchange flow rate whose secondary heat exchange flow rate is smaller than the benchmark secondary heat exchange flow rate.

8. The method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making according to claim 7, characterized in that, Extract the group with the smallest primary heat exchange flow rate from the groups with the same secondary heat exchange flow rate, and use the corresponding total heat exchange area in this group as the benchmark total heat exchange area. Then retain the groups with the same secondary heat exchange flow rate whose total heat exchange area is smaller than the benchmark total heat exchange area.

9. The method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making according to claim 8, characterized in that, Extract the group with the minimum primary heat exchange flow rate from the group with the minimum secondary heat exchange flow rate. Use the corresponding secondary heat exchange flow rate and total heat exchange area in this group as the benchmark secondary heat exchange flow rate and benchmark total heat exchange area. Retain the groups whose secondary heat exchange flow rate is smaller than the benchmark secondary heat exchange flow rate in the groups whose primary heat exchange flow rate is not the minimum. Also retain the groups whose total heat exchange area is smaller than the benchmark total heat exchange area in the groups whose primary heat exchange flow rate is not the minimum. This will give you all the optimized combinations of the optimal range of total heat exchange area.

10. The method for optimizing parameters of a marine circulating cooling water system based on multi-objective decision-making according to claim 9, characterized in that, Set the percentage increase in primary heat exchange flow rate ⊿Q f % and the percentage increase in secondary heat exchange flow rate ⊿Q s Alternatively, by locking the primary heat exchange temperature difference and the secondary heat exchange temperature difference, a unique optimal combination of the primary heat exchange cold source inlet temperature, the primary heat exchange cold source outlet temperature, the primary heat exchange flow rate, the primary heat exchange area, the secondary heat exchange flow rate, the secondary heat exchange area, and the total heat exchange area can be obtained.

Images