Sea water pump frequency conversion control system suitable for iCER system

Abstract

The invention discloses a seawater pump frequency conversion control system suitable for an iCER system. A high-position seabed box and a low-position seabed box are respectively connected with an iCER system plate heat exchanger and a central plate heat exchanger through a seawater header pipe via a seawater pump; and the iCER system plate heat exchanger is connected with an iCER low-temperature fresh water cooling system user, and returns to the iCER system plate heat exchanger after connection. And the central plate heat exchanger is connected with a low-temperature fresh water cooling system user through a three-way temperature control valve and a low-temperature fresh water lightering pump, and then returns to the central plate heat exchanger and the three-way temperature control valve. Under the condition of ensuring normal operation of the central fresh water cooling system and the iCER system, the power of the sea water pump can be reduced to the greatest extent, the purpose of saving energy is achieved, automatic operation and comprehensive monitoring of the low-temperature fresh water cooling system are realized to the greatest extent through design and logic control of the sensors, and the system is suitable for popularization and application. And the working intensity in the ship operation is reduced, the automatic operation level of the ship is provided, and the ship operation is more stable and safer.

Description

Technical Field

[0001] The invention belongs to the field of marine ship design and construction, and in particular relates to a seawater pump frequency conversion control system suitable for an iCER system. Background Art

[0002] The conventional ship low-temperature fresh water cooling system uses seawater pumps to transfer external seawater into the central plate heat exchanger, which then cools the low-temperature fresh water system. The low-temperature fresh water system provides cooling fresh water at a temperature of 36°C to the equipment that needs cooling in the ship through the mixing water method of the three-way temperature control valve.

[0003] However, along with the technology update of the main engine patentee, the main engine currently requires the cooling water temperature provided to the main engine to be as low as possible. The MAN B&W main engine requires the set temperature of the three-way temperature control valve to be 10°C, and the WinGD main engine requires the set temperature of the three-way temperature control valve to be 25°C.

[0004] In addition, when the external seawater temperature is low, the cooling efficiency of seawater is greatly improved, and the amount of seawater that can be provided by the seawater pump designed according to the set temperature of 32°C is too large, resulting in a waste of seawater pump power. Therefore, considering the operating costs of the ship, more and more ship owners choose to use variable frequency design for seawater pumps, that is, when the seawater temperature is low, reduce the power of the seawater pump and reduce the seawater flow rate. Under the premise of meeting the requirements of the cooling system, the power consumption of the seawater pump is minimized to save energy.

[0005] iCER is WinGD’s latest system for use with dual-fuel engines. The cooling system also requires a seawater pump to provide cooling seawater.

[0006] Therefore, while ensuring the normal operation of the low-temperature fresh water cooling system, the normal operation of the iCER cooling water system must also be considered. Simple frequency conversion control logic cannot meet the requirements, and a seawater pump frequency conversion control system suitable for the iCER system needs to be designed. Summary of the invention

[0007] In order to solve the above problems, the present invention proposes a seawater pump frequency conversion control system suitable for the iCER system, aiming to simultaneously ensure the normal operation of the ship's low-temperature fresh water cooling system and the iCER cooling water system, and to minimize the power of the seawater pump, thereby saving energy to the greatest extent while ensuring the normal operation of the ship's system. The technical solution adopted is: A seawater pump frequency conversion control system suitable for an iCER system. A high-level seabed box and a low-level seabed box are respectively connected to an iCER system plate heat exchanger and a central plate heat exchanger through a seawater main pipe and a seawater pump; the iCER system plate heat exchanger is connected to an iCER low-temperature fresh water cooling system user and returns to the iCER system plate heat exchanger after connection; the central plate heat exchanger is connected to a low-temperature fresh water cooling system user through a three-way temperature control valve and a low-temperature fresh water transfer pump, and then returns to the central plate heat exchanger and the three-way temperature control valve.

[0008] The seawater pump inlet is provided with a seawater pump inlet pressure difference sensor, the low-temperature seawater inlet of the central plate heat exchanger is provided with a temperature sensor, the low-temperature seawater outlet of the central plate heat exchanger is provided with a temperature sensor, the low-temperature seawater inlet of the central plate heat exchanger is provided with a temperature sensor and a pressure sensor, the low-temperature fresh water outlet of the central plate heat exchanger is provided with a temperature sensor, the seawater inlet of the iCER system plate heat exchanger is provided with a temperature sensor, the seawater outlet of the iCER system plate heat exchanger is provided with a temperature sensor, and the seawater pump frequency conversion control system control box is connected with the signals of each temperature sensor and pressure sensor.

[0009] According to the claim, a seawater pump frequency conversion control system suitable for an iCER system is characterized in that the minimum speed of the seawater pump frequency conversion is set to % of the maximum rated speed.

[0010] The above-mentioned seawater pump frequency conversion control system suitable for the iCER system, further, has two seawater pumps, one of which is a backup seawater pump. When the pressure difference sensor at the inlet of the seawater pump detects that the seawater pressure is less than or equal to .Mpa, the seawater pump frequency conversion control system control box automatically starts the backup seawater pump.

[0011] The above-mentioned seawater pump variable frequency control system suitable for the iCER system, further, the maximum temperature of the seawater entering the central plate heat exchanger is 32°C.

[0012] The above-mentioned seawater pump variable frequency control system suitable for the iCER system, further, the temperature difference of the central plate heat exchanger is 12°C~16°C.

[0013] The above-mentioned seawater pump variable frequency control system suitable for the iCER system further has a set temperature of the three-way temperature control valve being 25°C.

[0014] The above-mentioned seawater pump variable frequency control system suitable for the iCER system further has a temperature difference between the low-temperature fresh water outlet temperature of the central plate heat exchanger and the low-temperature seawater inlet temperature of the central plate heat exchanger set to 5°C.

[0015] The present invention meets the requirements of the current mainstream main engine with iCER system for the low-temperature fresh water cooling system. It can reduce the power of the seawater pump to the maximum extent possible while ensuring the normal operation of the central fresh water cooling system and the iCER system, thereby achieving the purpose of energy saving. At the same time, through the design of sensors and logical control, the automatic operation and comprehensive monitoring of the low-temperature fresh water cooling system are realized to the maximum extent possible, which reduces the workload during ship operation, improves the level of ship automation operation, and makes ship operation more stable and safe. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the system of the present invention; Among them, 1- low-level seabed box, 2- high-level seabed box, 3- seawater main pipe, 4- seawater pump, 5- iCER system plate heat exchanger, 6- central plate heat exchanger, 7- low-temperature fresh water cooling system three-way temperature control valve, 8- low-temperature fresh water transfer pump, 9- low-temperature fresh water outlet temperature sensor of central plate heat exchanger, 10- low-temperature fresh water inlet temperature sensor of central plate heat exchanger, 11- iCER system plate heat exchanger seawater outlet temperature sensor, 12- iCER system plate heat exchanger seawater inlet temperature sensor, 13- central plate heat exchanger low-temperature seawater outlet temperature sensor, 14- central plate heat exchanger low-temperature seawater inlet temperature sensor, 15- central plate heat exchanger low-temperature seawater inlet pressure sensor, 16- seawater pump inlet and outlet pressure difference sensor, 17- seawater pump frequency conversion control system control box, 18- low-temperature fresh water cooling system user, 19- iCER low-temperature fresh water cooling system user. DETAILED DESCRIPTION

[0017] The present invention will be further described in conjunction with the accompanying drawings. Example

[0018] The seawater enters the seawater main 3 through the high-level seabed tank 2 and the low-level seabed tank 1. The seawater pump 4 transports the seawater to the iCER system plate heat exchanger 5 and the central plate heat exchanger 6 to cool the fresh water entering the heat exchanger.

[0019] The fresh water cooled by the iCER system plate heat exchanger 5 enters the iCER low-temperature fresh water cooling system user 19 to cool related systems and equipment.

[0020] The fresh water cooled by the central plate heat exchanger 6 first passes through the low-temperature fresh water cooling system three-way temperature control valve 7, and after mixing with the high-temperature fresh water returned after passing through the low-temperature fresh water cooling system user 18, it is transferred to the low-temperature fresh water cooling system user 18 through the low-temperature fresh water transfer pump 8 to cool the relevant systems and equipment.

[0021] The seawater pump variable frequency control system control box 17 controls the motor speed of the seawater pump 4 by collecting signals from various sensors and three-way temperature control valves arranged on the system, so as to control the start and stop of the seawater pump and the seawater flow rate. Under the premise of meeting the normal operation of the cooling system, the seawater pump motor power is reduced to save energy.

[0022] The seawater pump frequency conversion control system control box 17 has three control modes, automatic frequency conversion mode, manual frequency conversion mode and fixed frequency mode. The automatic frequency conversion mode is that the seawater pump frequency conversion control system operates autonomously and controls the operation of the seawater pump according to the set control logic. The manual frequency conversion mode requires the crew to manually control the motor speed of the seawater pump. The fixed frequency mode is that when the seawater pump frequency conversion system fails, in order not to affect the operation of the cooling system, it will automatically switch to the seawater pump fixed frequency and reach the set maximum rated speed. At this time, the energy saving effect will not be considered.

[0023] At the same time, since the seawater pump runs in low speed mode for a long time and is prone to damage, the minimum speed of the seawater pump frequency conversion will be set, generally 60% of the maximum rated speed.

[0024] A seawater pump inlet and outlet pressure difference sensor 16 is installed at the inlet and outlet of the seawater pump 4 to monitor the inlet and outlet pressure difference of the seawater pump. When the pressure difference is too small, less than or equal to 0.02Mpa, it indicates that the seawater pump is faulty, and the seawater pump frequency conversion control system control box 17 will automatically start the standby seawater pump to ensure the normal operation of the cooling water system.

[0025] A temperature sensor 14 and a pressure sensor 15 are installed at the low-temperature seawater inlet of the central plate heat exchanger. When the seawater pressure is too low, less than or equal to 0.02Mpa, it indicates that the seawater pump and the seawater system have failed, and a low-pressure alarm will be issued, requiring the crew to check related equipment, valves, filters, etc.

[0026] In the design of the low-temperature fresh water cooling system, the maximum design temperature of seawater entering the central plate heat exchanger is 32°C. The seawater temperature is monitored by a temperature sensor 14 installed at the low-temperature seawater inlet. When the temperature exceeds 32°C, a high temperature alarm will be issued, requiring the crew to check related equipment, valves, filters, etc. and perform manual intervention.

[0027] A temperature sensor 13 is installed at the low-temperature seawater outlet of the central plate heat exchanger. By comparing the temperatures of the seawater inlet and outlet of the central plate heat exchanger, when the temperature difference is too large, exceeding the designed temperature difference of the central plate heat exchanger, generally 12°C~16°C, it means that the seawater flow is insufficient. The frequency conversion control system will increase the flow of the seawater pump and start the backup pump to run at the same time when necessary to ensure the normal operation of the cooling water system. At the same time, an alarm will be issued to prompt the crew to check the relevant systems.

[0028] A temperature sensor 9 is installed at the low-temperature fresh water outlet of the central plate heat exchanger to monitor the temperature of the fresh water after being cooled by the central plate heat exchanger and mixed with the returned high-temperature fresh water. According to the requirements of WinGD, the set temperature of the three-way temperature control valve of the low-temperature fresh water cooling system is 25°C. When the low-temperature fresh water outlet temperature of the central plate heat exchanger is higher than 25°C, the three-way temperature control valve will adjust the mixing ratio to reduce the temperature as much as possible. When the seawater temperature is high, exceeding 20°C, the low-temperature fresh water after being cooled by the central plate heat exchanger is already higher than 25°C. The three-way temperature control valve will be fully adjusted to the low-temperature fresh water outlet side of the central plate heat exchanger and will no longer mix with the returned high-temperature fresh water.

[0029] The seawater frequency conversion system will set the control logic. When the low-temperature seawater inlet temperature of the central plate heat exchanger exceeds 20°C, the temperature difference between the low-temperature fresh water outlet temperature of the central plate heat exchanger and the low-temperature seawater inlet temperature of the central plate heat exchanger is set to 5°C. When the temperature difference is greater than 5°C, the seawater frequency conversion system will increase the speed of the seawater pump and increase the amount of cooled seawater. If the requirements are still not met, the standby seawater pump will be further turned on and an alarm will be issued.

[0030] When the temperature difference is less than 5°C, the seawater frequency conversion system will reduce the speed of the seawater pump and reduce the amount of seawater to be cooled until the temperature difference stabilizes at 5°C or reaches the minimum speed set for the seawater pump, thereby achieving the purpose of saving energy.

[0031] When the low-temperature seawater inlet temperature of the central plate heat exchanger is lower than 20°C, the seawater frequency conversion system will not consider the temperature difference between the low-temperature fresh water outlet temperature of the central plate heat exchanger and the low-temperature seawater inlet temperature of the central plate heat exchanger, and will only focus on the low-temperature fresh water outlet temperature of the central plate heat exchanger. When the temperature is higher than 25°C, the seawater frequency conversion system will reduce the speed of the seawater pump and reduce the amount of cooled seawater until the temperature stabilizes at 25°C or reaches the minimum speed set by the seawater pump, thereby achieving the purpose of saving energy.

[0032] The low-temperature fresh water inlet temperature sensor 10 of the central plate heat exchanger does not participate in the control of the seawater frequency conversion system, but only serves as an inlet temperature display.

[0033] In addition to providing cooling seawater for the central plate heat exchanger, cooling seawater is also needed for the iCER system plate heat exchanger. When the seawater temperature is low or the cooling water demand of the low-temperature fresh water system is low, the demand for seawater from the central plate heat exchanger will decrease, and the seawater frequency conversion system will reduce the seawater pump power to the minimum value, which will lead to a decrease in the amount of seawater entering the iCER system plate heat exchanger. When the iCER system plate heat exchanger cannot meet the demand for seawater, it will affect the operation of the iCER system. Therefore, temperature sensors 11, 12 are added to the seawater inlet and outlet of the iCER system plate heat exchanger. When the temperature difference between the outlet and the inlet is too large, generally 12°C~16°C, the seawater pump frequency conversion system will increase the speed of the seawater pump until the temperature difference reaches a reasonable range.

Claims

1. A seawater pump frequency conversion control system suitable for iCER system, characterized in that: The high-level seabed box (2) and the low-level seabed box (1) are connected to the iCER system plate heat exchanger (5) and the central plate heat exchanger (6) respectively through the seawater main pipe (3) via the seawater pump (4); the iCER system plate heat exchanger is connected to the iCER low-temperature fresh water cooling system user (19), and after the connection, it returns to the iCER system plate heat exchanger; the central plate heat exchanger is connected to the low-temperature fresh water cooling system user (18) through the three-way temperature control valve (7) via the low-temperature fresh water transfer pump (8), and then returns to the central plate heat exchanger and the three-way temperature control valve; A seawater pump inlet pressure difference sensor (16) is provided at the inlet of the seawater pump, a temperature sensor (10) is provided at the low-temperature seawater inlet of the central plate heat exchanger, a temperature sensor (13) is provided at the low-temperature seawater outlet of the central plate heat exchanger, a temperature sensor (14) and a pressure sensor (15) are provided at the low-temperature seawater inlet of the central plate heat exchanger, a temperature sensor (9) is provided at the low-temperature fresh water outlet of the central plate heat exchanger, a temperature sensor (12) is provided at the seawater inlet of the iCER system plate heat exchanger, a temperature sensor (11) is provided at the seawater outlet of the iCER system plate heat exchanger, and a seawater pump frequency conversion control system control box (17) is connected to the temperature sensors and pressure sensor signals.

2. A seawater pump frequency conversion control system suitable for an iCER system according to claim 1, characterized in that: Set the minimum speed of the seawater pump variable frequency to 60% of the maximum rated speed.

3. A seawater pump frequency conversion control system suitable for an iCER system according to claim 1, characterized in that: There are two seawater pumps, one of which is a backup seawater pump. When the pressure difference sensor at the inlet of the seawater pump detects that the seawater pressure is less than or equal to 0.02Mpa, the seawater pump frequency conversion control system control box automatically starts the backup seawater pump.

4. A seawater pump frequency conversion control system suitable for an iCER system according to claim 1, characterized in that: The maximum temperature of seawater entering the central plate heat exchanger is 32°C.

5. The seawater pump frequency conversion control system suitable for the iCER system according to claim 1, characterized in that: The temperature difference of the central plate heat exchanger is 12℃~16℃.

6. A seawater pump frequency conversion control system suitable for an iCER system according to claim 1, characterized in that: The set temperature of the three-way temperature control valve is 25℃.

7. A seawater pump frequency conversion control system suitable for an iCER system according to claim 1, characterized in that: The temperature difference between the low-temperature fresh water outlet temperature of the central plate heat exchanger and the low-temperature seawater inlet temperature of the central plate heat exchanger is set to 5°C.

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