Ship cooling water control system and control method

Abstract

A ship cooling water control system and control method. In the ship cooling water control system, seawater discharged by a seawater cooling unit (1) and fresh water discharged by a fresh water cooling unit (2) exchange heat in a central cooler (5); the central cooler (5) is connected to a second input end of a three-way temperature control valve (6) so as to discharge the fresh water subjected to heat exchange into the three-way temperature control valve (6), and the three-way temperature control valve (6) is connected to a device unit (3); a first variable frequency drive (12) is provided between a control unit (4) and the seawater cooling unit (1); a second variable frequency drive (22) is provided between the control unit (4) and the fresh water cooling unit (2); and the control unit (4) is further electrically connected to a third temperature sensor (9) for monitoring the temperature of seawater. When a cooling water system needs to be controlled, the three-way temperature control valve (6), the seawater cooling unit (1) and the fresh water cooling unit (2) are jointly controlled by means of the control unit (4), and the operating power of the seawater cooling unit (1) and the operating power of the fresh water cooling unit (2) are more intelligently regulated and controlled by introducing an external real-time seawater temperature, a cooling water demand, and a working load, achieving an energy-saving effect while maintaining the cooling requirement of the device unit (3).

Description

A marine cooling water control system and control method TECHNICAL FIELD

[0001] The present application relates to the technical field of marine equipment cooling, in particular to a marine cooling water control system and control method. BACKGROUND

[0002] The function of the marine cooling system is to use seawater or freshwater to cool the excessive heat generated by the main engine and auxiliary system, so as to prevent the equipment from not working normally or being damaged due to high temperature. The whole central cooling system includes a seawater cooling system, a freshwater cooling system, a temperature control valve and a central cooler. The seawater cooling system is composed of a sea chest, a seawater main pipe, a seawater delivery pipe, a valve, a seawater pump and an outboard pipe; the freshwater cooling system is composed of a freshwater tank, a freshwater pump, a freshwater delivery pipe, a valve and the like.

[0003] During the operation of the ship, all cooling system equipment will participate in the work throughout the process. In order to reduce the energy consumption of the system, some ship owners will make the seawater pump into a frequency control, so as to achieve the effect of system energy saving. However, with the increase of electrical equipment, more and more equipment needs to be cooled, and the simple frequency conversion of the seawater pump cannot achieve good energy saving effect. In the current ship cooling scheme, the various energy-saving control devices are independent of each other and cannot work cooperatively, and there is also logical confusion among the control devices. Therefore, the existing cooling water control system cannot achieve good energy saving effect.

[0004] SUMMARY

[0005] The technical problem to be solved by the present application is how to connect the devices in the cooling water system to achieve energy saving effect. In order to solve the above technical problem, the present application provides a marine cooling water control system and control method, which comprises a seawater cooling unit, a freshwater cooling unit, a device unit, a control unit, a central cooler, a three-way temperature control valve and a temperature detection unit.

[0006] The output end of the seawater cooling unit is connected with the first end of the central cooler, the output end of the freshwater cooling unit is connected with the second end of the central cooler, and the seawater output by the seawater cooling unit and the freshwater output by the freshwater cooling unit are subjected to heat exchange in the central cooler.

[0007] The input end of the freshwater cooling unit is connected with the output end of the device unit, and the output end of the freshwater cooling unit is also connected with the first input end of the three-way temperature control valve. The third end of the central cooler is connected with the second input end of the three-way temperature control valve to input the heat-exchanged freshwater into the three-way temperature control valve, and the output end of the three-way temperature control valve is connected with the device unit.

[0008] The temperature detection unit comprises a first temperature sensor for monitoring the temperature of fresh water at the inlet of the equipment unit, a second temperature sensor for monitoring the temperature of fresh water at the outlet of the equipment unit, and a third temperature sensor for monitoring the temperature of sea water.

[0009] The control unit is electrically connected with the sea water cooling unit, the fresh water cooling unit, the equipment unit, the three-way temperature control valve, and the temperature detection unit respectively; a first frequency converter is arranged between the control unit and the sea water cooling unit; a second frequency converter is arranged between the control unit and the fresh water cooling unit.

[0010] Preferably, the first temperature sensor is arranged between the three-way temperature control valve and the equipment unit.

[0011] Preferably, the second temperature sensor is arranged between the equipment unit and the fresh water cooling unit, and a plurality of second temperature sensors are arranged corresponding to a plurality of electrical equipment in the equipment unit.

[0012] Preferably, the input end of the equipment unit is further provided with a differential pressure sensor, and the differential pressure sensor is electrically connected with the control unit.

[0013] Preferably, the sea water cooling unit comprises a plurality of parallel sea water pumps; and the fresh water cooling unit comprises a plurality of parallel fresh water pumps.

[0014] Preferably, a plurality of outlet valves are arranged corresponding to a plurality of electrical equipment in the equipment unit.

[0015] The application further provides a ship cooling water control method, which comprises the following steps:

[0016] S1、

[0017] The control unit acquires a first real-time temperature of sea water through the third temperature sensor, and controls the output power of the sea water cooling unit and the fresh water cooling unit according to the first real-time temperature;

[0018] S2, the control unit acquires a first temperature monitored by the first temperature sensor and a second temperature monitored by the second temperature sensor, and controls the three-way temperature control valve, the first frequency converter and the second frequency converter according to the first temperature, the second temperature and the sea water temperature as an adjusting signal;

[0019] S3, the control unit judges whether the first temperature and the second temperature exceed the corresponding preset temperature range, and when the first temperature and the second temperature both exceed the corresponding preset temperature range, the three-way temperature control valve is preferentially adjusted.

[0020] S4, when the first temperature and the second temperature still exceed the corresponding preset temperature range, judging whether the three-way temperature control valve is at the maximum opening, if the three-way temperature control valve opening is not at the maximum opening, adjusting to increase the opening of the three-way temperature control valve, if the three-way temperature control valve is at the maximum opening, adjusting the opening of the equipment unit outlet valve until the maximum;

[0021] S5, the control unit judges whether the first temperature and the second temperature are lower than the corresponding preset temperature range, if both are not lower than the corresponding preset temperature range, judging the sea water cooling unit power or fresh water cooling unit power required to be increased to meet the minimum cooling demand according to the sea water temperature, the first temperature, the second temperature, the cooling water demand of the equipment unit and the working load of the equipment unit, and correspondingly adjusting the sea water cooling unit power and / or fresh water cooling unit power through the first frequency converter and the second frequency converter.

[0022] Preferably, the preset temperature range is determined by the current sea water temperature, historical data and heat balance calculation book.

[0023] Preferably, in step S5, if the first temperature is higher than the corresponding preset temperature range, and the second temperature is lower than the corresponding preset temperature range, the running power of the sea water pump is increased through the first frequency converter, and the running power of the fresh water pump is reduced through the second frequency converter; if the first temperature is lower than the corresponding preset temperature range, and the second temperature is higher than the corresponding preset temperature range, the running power of the fresh water pump is preferentially increased through the second frequency converter; if the first temperature and the second temperature are both lower than the corresponding preset temperature range, the running power of the sea water pump and the running power of the fresh water pump are respectively reduced through the first frequency converter and the second frequency converter.

[0024] The ship cooling water control system and control method provided in the embodiment of the application have the following beneficial effects compared with the prior art:

[0025] When the cooling water system of the ship needs to be controlled, there are usually multiple adjustment means, the opening of the three-way temperature control valve, the power of the sea water cooling unit and the power of the fresh water cooling unit can all be adjusted to improve and meet the cooling effect, but the power consumption required is different under different adjustment means, the temperature of the external sea water, the load of the equipment unit and the cooling water demand will all affect the power consumption of the cooling water system; in the application, the control unit links the adjustment and control of the three-way temperature control valve, the sea water cooling unit and the fresh water cooling unit, and introduces the real-time sea water temperature, the cooling water demand and the working load of the equipment unit to more intelligently adjust and control the running power of the sea water cooling unit and the fresh water cooling unit, so that the running power of the sea water cooling unit or the fresh water cooling unit is reduced under the condition of stable cooling of the equipment unit, and the energy saving effect is realized. BRIEF DESCRIPTION OF DRAWINGS

[0026] Fig. 1 is a schematic diagram of the system of the present application;

[0027] Fig. 2 is a flowchart of the present application.

[0028] In the figure: 1, seawater cooling unit; 11, seawater pump; 12, first frequency converter; 2, freshwater cooling unit; 21, freshwater pump; 22, second frequency converter; 3, equipment unit; 31, differential pressure sensor; 4, control unit; 5, central cooler; 6, three-way temperature control valve; 7, first temperature sensor; 8, second temperature sensor; 9, third temperature sensor. DETAILED DESCRIPTION

[0029] The specific embodiments of the present application are described in further detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application, but are not intended to limit the scope of the present application.

[0030] As shown in Fig. 1, the preferred embodiment of the present application provides a ship cooling water control system and control method, which comprises a seawater cooling unit 1, a freshwater cooling unit 2, an equipment unit 3, a control unit 4, a central cooler 5, a three-way temperature control valve 6, and a temperature detection unit.

[0031] The output end of the seawater cooling unit 1 is connected to the first end of the central cooler 5, and the output end of the freshwater cooling unit 2 is connected to the second end of the central cooler 5. The seawater output by the seawater cooling unit 1 and the freshwater output by the freshwater cooling unit 2 exchange heat in the central cooler 5.

[0032] The input end of the freshwater cooling unit 2 is connected to the output end of the equipment unit 3, and the output end of the freshwater cooling unit 2 is also connected to the first input end of the three-way temperature control valve 6. The third end of the central cooler 5 is connected to the second input end of the three-way temperature control valve 6 to input the heat-exchanged freshwater into the three-way temperature control valve 6, and the output end of the three-way temperature control valve 6 is connected to the equipment unit 3.

[0033] The temperature detection unit comprises a first temperature sensor 7 for monitoring the temperature of the freshwater at the inlet of the equipment unit 3, a second temperature sensor 8 for monitoring the temperature of the freshwater at the outlet of the equipment unit 3, and a third temperature sensor 9 for monitoring the temperature of the seawater.

[0034] The control unit 4 is electrically connected to the seawater cooling unit 1, the freshwater cooling unit 2, the equipment unit 3, the three-way temperature control valve 6, and the temperature detection unit. The first frequency converter 12 is provided between the control unit 4 and the seawater cooling unit 1, and the second frequency converter 22 is provided between the control unit 4 and the freshwater cooling unit 2.

[0035] Specifically, in the present application, the seawater cooling unit 1 extracts low-temperature seawater in the seawater tank through the first end into the central cooler 5, and is discharged to the ship side through the fourth end of the central cooler 5, and the fresh water cooling unit 2 extracts fresh water in the equipment unit 3, wherein the first part of fresh water is input into the central cooler 5 through the second end to exchange heat with seawater to lower the temperature, and then input into the three-way temperature control valve 6 through the third end and flow back to the equipment unit 3 through the three-way temperature control valve 6, and the second part of fresh water is mixed with the cooled first part of fresh water in the three-way temperature control valve 6 and flows back to the equipment unit 3; and the control unit 4 is connected with the seawater cooling unit 1 and the fresh water cooling unit 2 through the first frequency converter 12 and the second frequency converter 22 respectively, and the control unit 4 is also electrically connected with the three-way temperature control valve 6; when the equipment starts, according to the current seawater temperature and the running data of the seawater cooling unit 1 and the fresh water cooling unit 2, the power of the seawater cooling unit 1 and the fresh water cooling unit 2 at the start is set, so that the seawater cooling unit 1 and the fresh water cooling unit 2 can meet the cooling demand while keeping a lower running power, thereby achieving the purpose of energy saving and avoiding power waste; when the temperature of the fresh water at the inlet of the equipment unit 3 is too high and the cooling effect of the cooling system needs to be improved, more fresh water is input into the central cooler 5 to participate in heat exchange by adjusting the opening of the three-way temperature control valve 6, thereby reducing the temperature of the fresh water output by the three-way temperature control valve 6, thereby improving the cooling effect of the fresh water on the equipment unit 3 and reducing the temperature of the fresh water at the inlet and outlet of the equipment unit 3; when the opening of the three-way temperature control valve 6 is opened to the maximum, but the temperature of the fresh water at the inlet and outlet of the equipment unit 3 is still too high, the power of the seawater cooling unit 1 and the fresh water cooling unit 2 can be calculated according to the current seawater temperature, the cooling water demand and the working load of the equipment unit 3 to achieve the best energy saving effect; when the seawater temperature is lower than the preset seawater temperature, the power of the seawater cooling unit 1 is increased and the power of the fresh water cooling unit 2 is partially reduced to transport more seawater to the central cooler 5 to participate in heat exchange, so that the temperature of the fresh water output by the three-way temperature control valve 6 is reduced to the lowest value corresponding to the preset temperature range, thereby keeping or even improving the cooling effect in the case of energy saving; when the working load of the equipment unit 3 becomes smaller or even part of the equipment is shut down, the running power of the fresh water cooling unit 2 can be reduced to reduce the circulating flow rate and flow of fresh water, thereby achieving energy saving while ensuring the cooling effect; when the working load of the equipment unit 3 becomes larger, the seawater cooling unit 1 and the fresh water cooling unit 2 can be adjusted in combination with the data of the current seawater temperature through model data calculation to achieve the best adjustment of the seawater cooling unit 1 and the fresh water cooling unit 2 under the condition of meeting the stable temperature of the fresh water at the inlet and outlet of the equipment unit 3, thereby achieving the energy saving effect; the seawater cooling unit 1 and the fresh water cooling unit 2 can also be adjusted in linkage, rather than directly adjusting the seawater cooling unit 1 or the fresh water cooling unit 2.

[0036] In some embodiments, a first temperature sensor 7 is arranged between the three-way temperature control valve 6 and the equipment unit 3, and is used to monitor the temperature of the fresh water entering the equipment unit 3. A second temperature sensor 8 is arranged between the equipment unit 3 and the fresh water cooling unit 2, and is provided with multiple temperature sensors corresponding to multiple electrical equipment in the equipment unit 3.

[0037] Specifically, the first temperature sensor 7 and the second temperature sensor 8 can respectively monitor the temperature of the fresh water entering and exiting the equipment unit 3, and can respectively represent the cooling condition of the equipment unit 3 and the heat exchange condition of the fresh water. In a specific embodiment, when the first temperature monitored by the first temperature sensor 7 exceeds the corresponding preset temperature range, it indicates that the heat exchange condition of the fresh water is not ideal, at which time the running power of the seawater pump 11 in the seawater cooling unit 1 can be increased to increase the circulation speed of the seawater, so as to reduce the monitored first temperature and meet the cooling requirements of the equipment unit 3. When the second temperature monitored by the second temperature sensor 8 exceeds the corresponding preset temperature range, it indicates that the cooling effect of the equipment is not ideal, which may be due to the excessive heat generated by the equipment under excessive load. At this time, the running power of the fresh water pump 21 in the fresh water cooling unit 2 can be increased to increase the circulation speed of the fresh water, so as to reduce the monitored second temperature and meet the cooling requirements of the equipment unit 3. Further, when the second temperature exceeds the corresponding preset temperature range and the seawater temperature is lower than the preset seawater temperature, the running power of the seawater cooling unit 1 can also be increased slightly to reduce the first temperature, so that the temperature of the fresh water entering the equipment unit 3 is at the lowest value within the corresponding preset temperature range, thereby reducing the second temperature and achieving energy saving effect while ensuring the cooling effect.

[0038] In some embodiments, the input end of the equipment unit 3 is also provided with a differential pressure sensor 31, which is electrically connected to the control unit 4.

[0039] Specifically, the differential pressure sensor 31 is used to monitor the pressure and flow of the fresh water entering the equipment unit 3. When the feedback value of the differential pressure sensor 31 decreases, it indicates that the flow and flow rate of the fresh water are decreasing, at which time the cooling effect of the equipment unit 3 may be affected. When the feedback value of the differential pressure sensor 31 is less than the preset feedback value and the second temperature is higher than the corresponding preset temperature range, the running power and speed of the fresh water pump 21 in the fresh water cooling unit 2 are increased to provide more fresh water for the equipment unit 3 to achieve the cooling effect.

[0040] In some embodiments, the seawater cooling unit 1 includes multiple seawater pumps 11 connected in parallel; and the fresh water cooling unit 2 includes multiple fresh water pumps 21 connected in parallel.

[0041] Specifically, in actual use, the seawater pump 11 in the seawater cooling unit 1 and the fresh water pump 21 in the fresh water cooling unit 2 are provided with multiple pumps, when the running power of the seawater cooling unit 1 or the fresh water cooling unit 2 needs to be adjusted, in addition to adjusting the running power of each seawater pump 11 or fresh water pump 21 to reduce the rotating speed, the running power of the seawater cooling unit 1 or the fresh water cooling unit 2 can also be reduced by closing some seawater pumps 11 or fresh water pumps 21, so as to achieve the purpose of energy saving.

[0042] In some embodiments, multiple outlet valves are provided in the device unit 3 corresponding to multiple electric devices. Specifically, when the first temperature and the second temperature both exceed the corresponding preset temperature range, in addition to adjusting the opening degree of the three-way temperature control valve 6, the opening degree of the outlet valve can also be adjusted, and the opening degree of the outlet valve is adjusted to the maximum, so that the fresh water can flow through the device unit 3 more quickly and conveniently, and the cooling of the device unit 3 is realized. Only when the opening degree of the three-way temperature control valve 6 and the opening degree of the outlet valve are both opened to the maximum, but the first temperature and the second temperature still exceed the corresponding preset temperature range, the running power of the seawater pump 11 or the fresh water pump 21 is adjusted in combination with the current seawater temperature, so that the cooling effect of the cooling system remains stable.

[0043] As shown in FIG. 2, the application also provides a ship cooling water control method, which comprises the following steps:

[0044] S1, the control unit 4 obtains the first real-time temperature of the seawater through the third temperature sensor 9, and controls the output power of the seawater cooling unit 1 and the fresh water cooling unit 2 according to the first real-time temperature;

[0045] S2, the control unit 4 obtains the first temperature monitored by the first temperature sensor 7 and the second temperature monitored by the second temperature sensor 8, and controls the three-way temperature control valve 6, the first frequency converter 12 and the second frequency converter 22 according to the first temperature, the second temperature and the seawater temperature as an adjustment signal;

[0046] S3, the control unit 4 judges whether the first temperature and the second temperature exceed the corresponding preset temperature range, and adjusts the three-way temperature control valve 6 when the first temperature and the second temperature both exceed the corresponding preset temperature range;

[0047] S4, when the first temperature and the second temperature still exceed the corresponding preset temperature range, it is judged whether the three-way temperature control valve 6 is at the maximum opening degree, if the opening degree of the three-way temperature control valve 6 is not at the maximum opening degree, the opening degree of the three-way temperature control valve 6 is continuously adjusted to increase, if the three-way temperature control valve 6 is at the maximum opening degree, the opening degree of the outlet valve of the device unit 3 is adjusted to the maximum;

[0048] S5, the control unit 4 judges whether the first temperature and the second temperature are lower than the corresponding preset temperature range, if both are not lower than the corresponding preset temperature range, the seawater temperature, the first temperature, the second temperature, the cooling water demand of the equipment unit 3 and the working load of the equipment unit 3 are used to judge the required increased seawater cooling unit 1 power or fresh water cooling unit 2 power, and the seawater cooling unit 1 power and / or fresh water cooling unit 2 power are correspondingly adjusted by the first frequency converter 12 and the second frequency converter 22.

[0049] Wherein, when the seawater pump 11 and the fresh water pump 21 are not started, the current seawater temperature and the running state of the equipment unit 3, that is, the working load, can be obtained, and then the seawater temperature and the working load of the equipment unit 3 are input into the model to obtain the minimum running number and running power of the seawater pump 11 and the minimum running number and running power of the fresh water pump 21 that meet the cooling demand, and the seawater pump 11 and the fresh water pump 21 are started with the data, so that the energy saving effect can be achieved, and the seawater pump 11 and the fresh water pump 21 are prevented from being started too much and the power being too large during starting, thereby causing energy waste. Further, when the first temperature sensor 7 and the second temperature sensor 8 monitor the first temperature and the second temperature respectively when the cooling system is stably running after the seawater pump 11 and the fresh water pump 21 are started for a period of time, the first temperature is used to represent the fresh water temperature before entering the equipment unit 3, and the second temperature is used to represent the fresh water temperature discharged by the equipment unit 3, in addition to the real-time seawater temperature and the fresh water demand and working load of the equipment unit 3, the above data are used as the adjustment signal, and the control unit 4 controls the running state of the seawater pump 11 and the fresh water pump 21 through the first frequency converter 12 and the second frequency converter 22. Further, the first temperature and the second temperature have corresponding preset temperature ranges, in an embodiment, the maximum value of the preset temperature range corresponding to the first temperature is 36 degrees Celsius, when the first temperature is monitored to exceed 36 degrees Celsius, it indicates that the fresh water temperature entering the equipment unit 3 is too high, which is not conducive to the cooling use of the equipment in the equipment unit 3, if the opening degrees of the three-way temperature control valve 6 and the outlet valve have been adjusted to the maximum, the current seawater temperature, the working load of the equipment unit 3 and how much the first temperature exceeds the corresponding preset temperature range are used to judge the required increased seawater pump 11 speed or fresh water pump 21 speed that meets the minimum cooling demand, the size of the power required to increase the different pump speeds is judged, and the speed of the seawater pump 11 or the fresh water pump 21 is increased with the size; when the first temperature and the second temperature are reduced to the corresponding preset temperature range by increasing the power of the seawater pump 11 which can meet the cooling demand, the seawater pump 11 is started preferentially, otherwise the fresh water pump 21 is started preferentially, thereby achieving the energy saving effect.

[0050] In another embodiment, the model can also determine how much power of the seawater pump 11 and the fresh water pump 21 needs to be adjusted to make the first temperature and the second temperature return to the normal range, and then the model is used to intelligently adjust the running power of the seawater pump 11 and the fresh water pump 21, instead of adjusting the function of the seawater pump 11 or the fresh water pump 21 alone, so as to achieve the best cooling use power through the joint adjustment and control of the seawater pump 11 and the fresh water pump 21, thereby achieving the energy saving effect.

[0051] In some embodiments, the preset temperature range is determined by the current seawater temperature, historical data and heat balance calculation book. The preset temperature range can be set according to the current seawater temperature and the state of the equipment unit 3 running load in the past history, so as to avoid that the preset temperature range is too high to cause poor cooling effect and affect the normal operation of the equipment unit 3, and also avoid that the preset temperature range is too low to cause energy waste.

[0052] In step S5 of some embodiments, if the first temperature is higher than the corresponding preset temperature range and the second temperature is lower than the corresponding preset temperature range, the running power of the seawater pump 11 is increased by the first frequency converter 12 and the running power of the fresh water pump 21 is decreased by the second frequency converter 22; if the first temperature is lower than the corresponding preset temperature range and the second temperature is higher than the corresponding preset temperature range, the running power of the fresh water pump 21 is preferentially increased by the second frequency converter 22; and if the first temperature and the second temperature are both lower than the corresponding preset temperature range, the running power of the seawater pump 11 and the running power of the fresh water pump 21 are respectively decreased by the first frequency converter 12 and the second frequency converter 22.

[0053] In summary, the embodiment of the present application provides a ship cooling water control system and control method, which orderly connects the three-way temperature control valve 6, the first frequency converter 12 and the second frequency converter 22 through the control unit 4. When the temperature is too high and the cooling system needs to be controlled, the opening of the three-way temperature control valve 6 is preferentially adjusted to improve the cooling effect, so as to avoid the energy loss caused by increasing the power of the seawater pump 11 or the fresh water pump 21. When the opening of the three-way temperature control valve 6 is maximum but the fresh water temperature is still too high, the current minimum power required to meet the minimum cooling demand can be determined according to the current seawater temperature and the current working load of the equipment unit 3, and the running state and the running power of the seawater pump 11 and the fresh water pump 21 are adjusted according to the power, so that the energy saving effect is further enhanced.

[0054] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make some improvements and replacements without departing from the technical principles of the present application, and these improvements and replacements should also be considered as the protection scope of the present application.

Claims

1. A ship cooling water control system, characterized in that: It includes seawater cooling unit, fresh water cooling unit, equipment unit, control unit, central cooler, three-way temperature control valve and temperature detection unit; The output end of the seawater cooling unit is connected to the first end of the central cooler, and the output end of the freshwater cooling unit is connected to the second end of the central cooler. The seawater output from the seawater cooling unit and the fresh water output from the freshwater cooling unit are heat exchanged in the central cooler. The input end of the fresh water cooling unit is connected to the output end of the equipment unit, and the output end of the fresh water cooling unit is also connected to the first input end of the three-way temperature control valve; the third end of the central cooler is connected to the second input end of the three-way temperature control valve to input the heat-exchanged fresh water into the three-way temperature control valve, and the output end of the three-way temperature control valve is connected to the equipment unit; The temperature detection unit includes a first temperature sensor for monitoring the temperature of fresh water at the inlet of the equipment unit, a second temperature sensor for monitoring the temperature of fresh water at the outlet of the equipment unit, and a third temperature sensor for monitoring the temperature of sea water; The control unit is electrically connected to the seawater cooling unit, the fresh water cooling unit, the equipment unit, the three-way temperature control valve and the temperature detection unit respectively; a first frequency converter is provided between the control unit and the seawater cooling unit; a second frequency converter is provided between the control unit and the fresh water cooling unit.

2. The ship cooling water control system according to claim 1, characterized in that: The first temperature sensor is arranged between the three-way temperature control valve and the equipment unit.

3. The ship cooling water control system according to claim 1, characterized in that: The second temperature sensor is disposed between the equipment unit and the fresh water cooling unit, and a plurality of the second temperature sensors are disposed corresponding to the plurality of electrical devices in the equipment unit.

4. The ship cooling water control system according to claim 1, characterized in that: The input end of the equipment unit is further provided with a pressure difference sensor, and the pressure difference sensor is electrically connected to the control unit.

5. The ship cooling water control system according to claim 1, characterized in that: The seawater cooling unit includes a plurality of seawater pumps connected in parallel; the freshwater cooling unit includes a plurality of freshwater pumps connected in parallel.

6. The ship cooling water control system according to claim 1, characterized in that: The equipment unit is provided with a plurality of outlet valves corresponding to a plurality of electrical devices.

7. A ship cooling water control method, characterized in that: The ship cooling water control system according to any one of claims 1 to 7 comprises the following steps: S1. A control unit obtains a first real-time temperature of seawater through a third temperature sensor, and controls the output power of the seawater cooling unit and the fresh water cooling unit according to the first real-time temperature; S2. The control unit obtains a first temperature monitored by the first temperature sensor and a second temperature monitored by the second temperature sensor, and controls the three-way temperature control valve, the first frequency converter, and the second frequency converter according to the first temperature, the second temperature, and the seawater temperature as adjustment signals; S3, the control unit determines whether the first temperature and the second temperature exceed the corresponding preset temperature range, and when both the first temperature and the second temperature exceed the corresponding preset temperature range, preferentially adjusts the three-way temperature control valve; S4. When the first temperature and the second temperature still exceed the corresponding preset temperature range, determine whether the three-way temperature control valve is at the maximum opening; if the three-way temperature control valve is not at the maximum opening, continue to adjust and increase the opening of the three-way temperature control valve; if the three-way temperature control valve is at the maximum opening, adjust the opening of the equipment unit outlet valve to the maximum; S5. The control unit determines whether the first temperature and the second temperature are lower than the corresponding preset temperature ranges. If both are not lower than the corresponding preset temperature ranges, the control unit determines the amount of seawater cooling unit power or freshwater cooling unit power that needs to be increased to meet the minimum cooling demand based on the seawater temperature, the first temperature, the second temperature, the cooling water demand of the equipment unit, and the workload of the equipment unit, and adjusts the seawater cooling unit power and / or the freshwater cooling unit power accordingly through the first inverter and the second inverter.

8. The ship cooling water control method according to claim 7, characterized in that: The preset temperature range is determined by combining the current seawater temperature with historical data and according to a heat balance calculation sheet.

9. The ship cooling water control method according to claim 7, characterized in that: In step S5, if the first temperature is higher than the corresponding preset temperature range and the second temperature is lower than the corresponding preset temperature range, the operating power of the seawater pump is increased by the first inverter, and the operating power of the fresh water pump is reduced by the second inverter; if the first temperature is lower than the corresponding preset temperature range and the second temperature is higher than the corresponding preset temperature range, the operating power of the fresh water pump is preferentially increased by the second inverter; if both the first temperature and the second temperature are lower than the corresponding preset temperature range, the operating power of the seawater pump and the operating power of the fresh water pump are respectively reduced by the first inverter and the second inverter.

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