Ship cooling water system modeling debugging method

Abstract

The invention provides a ship cooling water system modeling and debugging method, which comprises the following steps of: performing parametric modeling on a cooling water system which is the most complicated pipeline system in a ship building process, and pre-judging the opening degrees of each branch and each valve of the system according to limited input conditions in combination with a numerical simulation calculation platform and an iterative optimization strategy; and important reference is provided for field debugging. Meanwhile, according to the method, serial and parallel valve position-flow control is conducted on a control branch step by step, the calculation time is reasonably saved, and a result meeting the flow deviation requirement can be obtained as soon as possible. Besides, when some ship systems are relatively complex in composition and a result meeting the flow deviation is difficult to obtain through full-system simulation, the same modeling debugging effect can be achieved in a system partition mode. According to the method, the field debugging work of the ship cooling water system can be more efficiently completed, and a theoretical reference is provided for operation and maintenance of the cooling water system when the ship sails under multiple working conditions after being put into operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship cooling water configuration, in particular to a ship cooling water system modeling and debugging method. BACKGROUND

[0002] In the field of shipbuilding, the debugging of low-temperature fresh water cooling system is one of the indispensable works before delivery. The quality of the debugging work of the low-temperature fresh water cooling system has a very important influence on the quality of the whole ship, and the quality of the debugging work will affect the safe and stable operation of the ship cooling box, air conditioner, main engine, various electrical devices and other equipment. Good cooling water system debugging work completion is an important part of the quality of the ship.

[0003] During the navigation and berthing of the ship, a large number of equipment (including mechanical equipment, electrical equipment, etc.) need to be cooled during their normal operation, and the heat dissipation required by different equipment is quite different, which puts different demands on the cooling water quantity. When the cooling water is distributed, both "less" and "excessive" will have a negative impact, especially when the cooling water quantity is insufficient, which will cause the temperature of the equipment to be too high, which directly affects the functionality of the corresponding system and the safe operation of the whole ship. Taking the diesel engine as an example, insufficient cooling will cause the parts to be overheated, the cylinder temperature to rise, and long-term operation under such conditions will lead to a decrease in the mechanical properties of the main engine materials, deformation due to thermal stress when the temperature exceeds the normal working range, and even damage. Excessive cooling will cause too much heat to be taken away by the cooling water, thereby reducing the economy of the diesel engine operation. If the main engine uses fuel with a high sulfur content, then insufficient cooling water quantity may form sulfuric acid on the inner wall of the cylinder and cause corrosion. Therefore, the reasonable distribution of the flow of the cooling water system is very important.

[0004] For the flow distribution of the cooling water, the site mainly relies on the experience-based debugging method, which continuously adjusts the valve or the throttle orifice plate to continuously try and error to complete the empirical evaluation of the flow range of each branch, thereby completing the distribution and debugging of the pipe network flow. This adjustment process is difficult and time-consuming, and often causes the throttle orifice plate to be scrapped due to improper aperture adjustment, resulting in a huge waste of labor and materials, so there is an urgent need for a ship cooling water system modeling and debugging method to provide support for the debugging of the ship cooling water system before delivery and the operation and maintenance after delivery. SUMMARY

[0005] In view of the above-mentioned shortcomings of the prior art, the present application provides a ship cooling water system modeling and debugging method, which comprises the following steps:

[0006] S1, cooling water system model construction: based on fluid calculation simulation software, all pipes, pipe accessories and various cooling water user equipment are connected according to technical documents, the pipe accessories including valves, tees, elbows and reducers;

[0007] S2, electric control setting of valve model: all valves involved in the system are set as electric control valves of corresponding models;

[0008] S3, boundary condition setting: including pipeline parameter and pipeline accessory parameter, equipment inlet and outlet parameter, pump performance curve, fluid parameter, and pressure drop and flow value of each equipment under rated working condition;

[0009] S4, first-stage valve position setting: initial valve positions of all valves are set as full opening state, and opening degree of each valve position is adjusted in the setting process;

[0010] S5, after setting, main equipment branch flow calculation: the simulation software calculates main equipment branch flow of the system to be concerned according to the boundary condition in step S3;

[0011] S6, branch flow deviation comparison: each branch calculated flow is compared with actual demand flow one by one, if the deviation is within the preset deviation, the valve position is output, if there is a branch flow deviation greater than the preset deviation, step S7 is entered;

[0012] S7, establishment of flow control logic of serial valve position: for the two valves before and after the valve position of the equipment with the branch flow deviation greater than the preset deviation, the automatic control logic related to the branch flow is established, and the cycle number of cycle a is increased by one.

[0013] Optionally, the following steps are further included:

[0014] S8, judgment of whether the cycle number of cycle a is less than the preset number, if yes, step S4 is returned, if no, step S9 is entered;

[0015] S9, establishment of flow control logic of parallel valve position: for all valves in the parallel branch associated with the to-be-adjusted branch with the flow deviation greater than the preset deviation, the automatic control logic related to the flow of the to-be-adjusted branch is established;

[0016] S10, second-stage valve position setting: the valve position value in the last iteration calculation in the first-stage valve position setting process is taken as the initial value of the second-stage valve position setting, and the opening degree of the valve position is adjusted in the setting process.

[0017] Optionally, the following steps are further included:

[0018] S11, after setting, main equipment branch flow calculation: main equipment branch flow of the system to be concerned is calculated;

[0019] S12, branch flow deviation comparison: compare each branch calculated flow with actual demand flow one by one, if the deviation is within the preset deviation, output the valve position; if there is a branch flow deviation greater than the preset deviation, the cycle b number m increases by 1, and step S13 is entered;

[0020] S13, judge whether the cycle number of cycle b is less than the preset number, if not, return to step S10; if yes, enter step S14.

[0021] Optionally, the following steps are further included:

[0022] S14, establish the next level partition: partition the current level cooling water system according to the location distribution of the cooling water users and the principle design, calculate each partition respectively, and no longer perform the overall calculation of the current level system;

[0023] S15, initialize the boundary conditions of each partition: take the last calculation result in the second stage valve position setting process as the initial condition of the partition calculation, and obtain the valve position setting value, and enter step S16;

[0024] S16, in each partition, calculate the main equipment branch flow: calculate the main equipment branch flow of the system that needs to be paid attention to;

[0025] S17, branch flow deviation comparison in the partition: compare the calculated flow of each branch in the partition with the actual demand flow one by one, if the deviation is within the preset deviation, output the valve position; if there is a branch flow deviation greater than the preset deviation, enter step S7 to establish the control logic of the series valve position in the partition again and cycle.

[0026] Optionally, in step S7, the automatic control logic related to the branch flow includes: if the branch flow is lower than the demand value, open the inlet valve; if it is higher than the demand value, close the inlet valve.

[0027] Optionally, in step S9, the automatic control logic related to the to-be-adjusted branch flow is established for all parallel branches, including: if the to-be-adjusted branch flow is lower than the demand value, close the parallel branch valve, if it is higher than the demand value, open the parallel branch valve.

[0028] Optionally, the preset deviation is 10%.

[0029] Optionally, the preset number is 20 times.

[0030] As described above, the present application provides a ship cooling water system modeling debugging method, which parameterizes the cooling water system, the most complex pipeline system in the shipbuilding process, and according to the limited input conditions, combines the numerical simulation calculation platform and the iterative optimization strategy to pre-judge the opening of each branch and each valve of the system, and provides an important reference for the on-site debugging. At the same time, the method saves the calculation time reasonably and can get the result meeting the flow deviation requirement as soon as possible by step-by-step series and parallel valve position-flow control of the control branch. In addition, when the composition of some ship systems is relatively complex and it is difficult to get the result meeting the flow deviation through full system simulation, the same modeling debugging effect can also be achieved in the form of system partition. The present application can more efficiently complete the on-site debugging work of the ship cooling water system, shorten the delivery cycle, accumulate relevant washing data, and provide a theoretical reference for the operation and maintenance of the cooling water system of the ship when sailing under multiple working conditions after being put into operation. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The flowchart of the modeling debugging method in the present application is shown.

[0032] Figure 2 The valve position opening-resistance characteristic curve in the present application is shown.

[0033] Figure 3 The partitioning diagram of the cooling water system in the present application is shown. DETAILED DESCRIPTION

[0034] The embodiments of the present application will be described in detail below with specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied in other different specific embodiments, and each detail in the present specification can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0035] It should be noted that the diagrams provided in the present embodiment only illustrate the basic concept of the present application in a schematic manner, and only show the components related to the present application in the diagrams, not the number, shape and size of the components when actually implemented. The actual implementation of each component may be randomly changed in shape, number and proportion, and the component layout pattern may also be more complex.

[0036] The valve of the ship cooling water system usually has only two states of opening and closing. When the opening and closing states of the valve cannot meet the flow requirement of the pipe network system in the running state, a throttle orifice plate is generally used to adjust the pressure. In the field debugging process, due to the complexity of the pipe network, the large number of equipment and valves, and especially the unknown corresponding relationship between the valve opening and the resistance coefficient, the throttle orifice plate is easily prepared unreasonably. After the throttle orifice plate is installed, its structure is fixed, and the orifice diameter can only be adjusted by continuously replacing the throttle orifice plate or modifying the structure of the orifice plate on site to achieve the actual required pipeline flow. The adjustment process is difficult and long, and the throttle orifice plate is often scrapped due to improper orifice diameter adjustment, resulting in a huge waste of labor and materials, so a ship cooling water system modeling and debugging method is urgently needed to provide support for the debugging of the ship cooling water system before delivery and the operation and maintenance of the ship cooling water system after delivery.

[0037] In view of the improvement space encountered in the ship pipeline series washing process, the present application provides a new ship cooling water system modeling and debugging method, which aims to more efficiently complete the field debugging work of the ship cooling water system, shorten the delivery cycle, accumulate related series washing data, and provide a theoretical reference for the operation and maintenance of the cooling water system of the ship when sailing under multiple working conditions after being put into operation.

[0038] As shown in Figure 1 , the present application provides a ship cooling water system modeling and debugging method, comprising the following steps:

[0039] S1, cooling water system model construction: based on fluid calculation simulation software, all pipelines, pipeline accessories (valves, tees, elbows, reducers, etc.) and various cooling water user equipment are connected according to technical documents; the purpose of this step is to convert the actual physical system (pipeline, equipment, accessory) into a model that can be recognized by a computer.

[0040] Specifically, existing fluid calculation simulation software such as AFT Fathom, ANSYS, etc. can be used for cooling water flow simulation. Regardless of the simulation software, the simulation process needs to meet the basic pipe network hydraulic model and follow the following rules:

[0041] Node equation (mass conservation): the sum of the flow rates into any node is zero.

[0042] Loop equation (energy conservation): around any closed loop, the sum of the pressure drops (including valves, equipment, pipe friction) of all pipe fittings is zero.

[0043] Pipe pressure drop equation: Darcy-Weisbach or Hazen-Williams formula is usually used.

[0044] Valve model: Valve is modeled as a local resistance element, whose pressure drop is: ΔΡ = Kv x p x v2 / 2 or more commonly used ΔΡ = (G / Kv)2. Where Kv(flow coefficient) is the key parameter to characterize the valve opening.

[0045] S2, Valve model electric control setting: all valves involved in the system (including manually adjusted valves, remote control valves and automatically adjusted valves) are set as corresponding type of electric control valve, and the control logic is to be determined. Usually there are many types of valves in a system, and each type of valve has a specific flow characteristic curve; taking a ball valve as an example, the valve resistance loss and valve position (opening) curve is as shown in the figure. Figure 2 The purpose of this step is to give the valve the attribute of remotely adjustable opening.

[0046] S3, Boundary condition setting: including pipeline parameters and pipeline accessory parameters, equipment inlet and outlet parameters, pump performance curve, fluid parameters (density, temperature and pressure), etc., as well as the pressure drop and flow value of each device under rated working condition (generally speaking, there are only a small amount of such data). Boundary conditions are known parameters required by simulation software for solving, which are not limited to the above parameters and can be increased or decreased as needed.

[0047] Specifically, the pipeline parameters include pipeline size, length, and inner wall roughness; the pipeline accessory parameters include the resistance coefficient; the equipment inlet and outlet parameters include the inlet pressure and outlet pressure of the cooling water flowing through the user equipment to be cooled, to ensure that the equipment can be normally cooled. The pump performance curve includes (head-flow relationship), which is the "power source" of the system. The fluid parameters include density, viscosity, etc., which determine the physical properties of the fluid. The pressure drop and flow value of each device under rated working condition, the pressure drop = inlet pressure - outlet pressure, are used to determine how much cooling water is needed for the device to work effectively.

[0048] Based on the built-in physical laws such as mass conservation and energy conservation, the simulation software solves the pressure of each node and the flow of each branch in the entire network according to these inputs.

[0049] S4, First stage valve position setting: the initial valve position of all valves is set to full opening state, and the opening of each valve position is adjusted during the setting process;

[0050] S5, After setting, calculate the flow of the main equipment branch (N): according to the boundary conditions in step S3, calculate the flow of the main equipment branch of the system to be concerned;

[0051] S6, branch flow deviation comparison: compare each branch calculated flow with actual demand flow one by one, if the deviation is within the preset deviation (10%), output the valve position; if there is a branch flow deviation greater than the preset deviation (10%), go to step S7; the preset deviation here is not limited to 10%, but also can be 8%, 12% and other values.

[0052] S7, establish flow control logic of serial valve position: for the equipment with branch flow deviation greater than the preset deviation (10%) located in the front and back two valves of the inlet and outlet, the automatic control logic related to the branch flow is established, and the number of cycles of cycle a is increased once;

[0053] For example, if the branch flow is lower than the demand value, open the inlet valve; if it is higher than the demand value, close the inlet valve. This control logic will be automatically executed in the next iteration calculation. This step can more accurately and independently control the flow of the branch by designing the control logic of the two valves (for example, one is mainly responsible for setting the flow, and the other is responsible for compensating the pressure fluctuation), while minimizing the interference to other parts of the system. This is equivalent to adding an independent and high-precision flow control to the branch.

[0054] S8, judge whether the number of cycles of cycle a is less than the preset number (20 times), if yes, return to step S4; if no, go to step S9. The purpose of this step is to make a cycle judgment:

[0055] Continue the cycle: if the number of cycles of cycle a is less than the preset number (20 times), return to S4, and take the last adjusted valve position as the new starting point to calculate, test and adjust again. This process will be repeated continuously to try to converge to a stable state by adjusting only the valves of the problem branch itself.

[0056] Break out of the loop: if 20 cycles are not met, it means that only adjusting the valves of the problem branch itself cannot effectively solve the problem. At this time, the process enters the second stage.

[0057] S9, establish flow control logic of parallel valve position: for all the valves of the parallel branches associated with the to-be-adjusted branch with flow deviation greater than the preset deviation (10%), the automatic control logic related to the flow of the to-be-adjusted branch is established;

[0058] This step starts to use a more complex strategy to consider the mutual influence between branches. For each to-be-adjusted branch with deviation > preset deviation (10%), find the valves of all parallel branches; if the flow of the to-be-adjusted branch is lower than the demand value, close the valves of the parallel branches, and if it is higher than the demand value, open the valves of the parallel branches. For example, if the flow of A branch is too low, close the valves of B and C branches parallel to it, so as to squeeze more flow to A branch.

[0059] S10, second stage valve position setting: taking the valve position value at the last iteration calculation in the first stage valve position setting process as the initial value of the second stage valve position setting, adjusting the opening of the valve position in the setting process;

[0060] S11, after setting, calculating the flow test of the main equipment branch (N in total): calculating the flow of the main equipment branch of the system to be concerned;

[0061] S12, branch flow deviation comparison: comparing the calculated flow of each branch with the actual demand flow one by one, if the deviation is within the preset deviation (10%), output the valve position; if there is a branch flow deviation greater than the preset deviation (10%), the cycle b number m increases by 1, and step S13 is entered;

[0062] S13, judging whether the cycle number of cycle b is less than the preset number (20 times), if not, returning to step S10; if yes, entering step S14;

[0063] S14, establishing the next level partition: partitioning the current level cooling water system according to the location distribution of the cooling water users (such as different decks, front and rear cabins, left and right sides) and the principle design, calculating each partition respectively, and no longer performing the overall calculation of the current level system, as shown in Figure 3 ;

[0064] S15, initialization of boundary conditions of each partition: taking the last calculation result in the second stage valve position setting process as the initial condition of the partition calculation, and obtaining the valve setting value, and entering step S16;

[0065] S16, in each partition, calculating the flow test of the main equipment branch (p in total): calculating the flow of the main equipment branch of the system to be concerned;

[0066] S17, branch flow deviation comparison in the partition: comparing the calculated flow of each branch in the partition with the actual demand flow one by one, if the deviation is within the preset deviation (10%), output the valve position; if there is a branch flow deviation greater than the preset deviation (10%), entering step S7 to establish the control logic of the series valve position in the partition again and circulating.

[0067] In the above valve setting process, first, the simplest local adjustment strategy (series valve control) is tried, when the simple strategy fails, a more complex strategy considering system coupling (parallel valve control) is introduced. When parallel valve control still cannot be solved, the complex system is decomposed into smaller and more manageable subsystems, and then debugged by partition.

[0068] The whole process relies on multiple iterative calculations, constantly correcting control actions (valve opening) through feedback (deviation of calculated flow from required flow), ultimately approaching the target state. At the same time, by setting the maximum number of iterations (20), it ensures that the process will not run indefinitely, preventing dead loops, and switching to more advanced strategies at the appropriate time.

[0069] In summary, the present application provides a ship cooling water system modeling and debugging method, which parameterizes the cooling water system, the most complex piping system in the shipbuilding process, and according to the limited input conditions, combines numerical simulation platform and iterative optimization strategy to predict the opening of each branch and each valve of the system, providing an important reference for on-site debugging. At the same time, this method can reasonably save calculation time and quickly get the results that meet the flow deviation requirements by step-by-step series and parallel valve-flow control of the control branch. In addition, when some ship systems are complex and difficult to get the results that meet the flow deviation through full system simulation, the same modeling and debugging effect can be achieved in the form of system partition. The present application can more efficiently complete the on-site debugging of the ship cooling water system, shorten the delivery cycle, accumulate relevant washing data, and provide a theoretical reference for the operation and maintenance of the cooling water system of the ship under multiple working conditions when it is put into operation.

[0070] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical idea disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method for modeling and debugging a ship cooling water system, characterized in that, Includes the following steps: S1. Cooling water system model construction: Based on fluid calculation simulation software, all pipelines, pipe fittings and various cooling water user equipment are connected according to the technical documents. Pipe fittings include valves, tees, elbows and reducers. S2. Valve Model Electrical Control Setting: Set all valves involved in the system to the corresponding model of electrically controlled valve; S3. Boundary condition setting: including pipeline parameters and pipeline accessory parameters, equipment inlet and outlet parameters, pump performance curves, fluid parameters, and pressure drop and flow rate values ​​of each piece of equipment under rated operating conditions; S4. First stage valve position setting: The initial valve position of all valves is set to fully open. During the setting process, the opening degree of each valve position is adjusted. S5. After tuning, verify the flow rate of the main equipment branches: The simulation software calculates the flow rate of the main equipment branches that the system needs to focus on based on the boundary conditions in step S3. S6. Branch flow deviation comparison: Compare the calculated flow of each branch with the actual required flow one by one. If the deviation is within the preset deviation, output the valve position; if there is a branch flow deviation greater than the preset deviation, proceed to step S7. S7. Establish flow control logic for series valve positions: For the two valves before and after the inlet and outlet of the equipment where the branch flow deviation is greater than the preset deviation, establish automatic control logic related to the flow of the branch, and at the same time increase the number of cycles of loop a by one.

2. The method for modeling and debugging a ship cooling water system according to claim 1, characterized in that, It also includes the following steps: S8. Determine whether the number of iterations of loop a is less than the preset number. If yes, return to step S4; otherwise, proceed to step S9. S9. Establish flow control logic for parallel valve positions: For valves in all parallel branches associated with the branch to be regulated where the flow deviation is greater than the preset deviation, establish automatic control logic related to the flow of the branch to be regulated. S10, Second stage valve position setting: The valve position value calculated during the last iteration of the first stage valve position setting process is used as the initial value for the second stage valve position setting. The valve position opening is adjusted during the setting process.

3. The method for modeling and debugging a ship cooling water system according to claim 2, characterized in that, It also includes the following steps: S11. After tuning, verify the calculated flow rate of the main equipment branches: calculate the flow rate of the main equipment branches that the system needs to focus on; S12, Branch flow deviation comparison: Compare the calculated flow of each branch with the actual required flow one by one. If the deviation is within the preset deviation, output the valve position; if there is a branch flow deviation greater than the preset deviation, the number of cycles b m is increased by 1, and proceed to step S13. S13. Determine whether the number of iterations of loop b is less than the preset number. If not, return to step S10. If so, proceed to step S14.

4. The method for modeling and debugging a ship cooling water system according to claim 3, characterized in that, It also includes the following steps: S14. Establish the next level of partition: Divide the cooling water system of this level into partitions according to the location distribution of cooling water users and the principle design, calculate each partition separately, and no longer perform the overall calculation of this level of system. S15. Initialize the boundary conditions of each partition: Use the last calculation result in the second stage valve position setting process as the initial condition for partition calculation, obtain the valve position setting value, and proceed to step S16. S16. Within each partition, verify the flow rate of the main equipment branches: calculate the flow rate of the main equipment branches that the subsystem needs to focus on; S17. Branch flow deviation comparison within the partition: Compare the calculated flow of each branch within the partition with the actual required flow one by one. If the deviation is within the preset deviation, output the valve position; if there is a branch flow deviation greater than the preset deviation, proceed to step S7 again to establish the control logic of the series valve position within the partition and loop.

5. The method for modeling and debugging a ship cooling water system according to claim 4, characterized in that: In step S7, establishing automatic control logic related to the flow rate of the branch includes: if the flow rate of the branch is lower than the demand value, then open its inlet valve; if it is higher than the demand value, then close its inlet valve.

6. The method for modeling and debugging a ship cooling water system according to claim 4, characterized in that: In step S9, the valves in all parallel branches establish automatic control logic related to the flow rate of the branch to be regulated, including: if the flow rate of the branch to be regulated is lower than the demand value, the valves of the parallel branches are closed; if the flow rate is higher than the demand value, the valves of the parallel branches are opened.

7. The method for modeling and debugging a ship cooling water system according to claim 1, characterized in that: The preset deviation is 10%.

8. The method for modeling and debugging a ship cooling water system according to claim 1, characterized in that: The preset number of attempts is 20.

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