Method and system for reducing energy consumption of low-temperature cooling water system of large ship

Abstract

The invention relates to a method and system for reducing energy consumption of a low-temperature cooling water system of a large ship, and the method comprises the steps that the low-temperature cooling water system is divided into a main engine cooling water subsystem and an auxiliary engine cooling water subsystem, and the main engine cooling water subsystem is used for cooling equipment related to main engine operation; the auxiliary machine cooling water subsystem is used for cooling equipment related to auxiliary machine operation, and the low-temperature cooling water system provides a power source for cooling water flow through a cooling water pump set with frequency conversion control; when only the auxiliary machine cooling water subsystem is needed to operate, the main machine cooling water subsystem is isolated, and the cooling water pump set is controlled to be used in a power reduction mode; when the main engine cooling water subsystem and the auxiliary engine cooling water subsystem are both normally used, the cooling water pump set is controlled to operate in a variable frequency mode with the main engine load percentage as a variable factor, the characteristics of the low-temperature cooling water system of a large ship that the minimum flow and the flow change amplitude are large can be adapted, and cooling water pump power consumption is reduced in time; the method has the advantages of remarkable consumption reduction, small implementation change, high universality and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy saving of ship cooling water systems, and particularly relates to a method and a system for reducing the energy consumption of a low-temperature cooling water system of a large ship. Background Art

[0002] The low-temperature cooling water system of a ship is an important part of the ship cooling system, mainly used for cooling equipment such as the air cooler of the ship's main engine, the lubricating oil cooler, the generator, and the air conditioner. The low-temperature cooling water is pumped and circulated by a cooling water pump to take away the heat generated during the operation of the equipment, prevent the equipment from deteriorating, being damaged or even malfunctioning due to excessive temperature, and ensure the normal operation of each system of the ship. In the past, during the shipping process of the ship, regardless of whether the ship is in a sailing state or a docked state, and regardless of how many equipment in its low-temperature cooling water system are shut down, the entire low-temperature cooling water system has always been in continuous operation. Therefore, the largest energy-consuming equipment, that is, the cooling water pump, has always been in a state of full load, full power, and continuous operation without interruption, and will not change due to changes in the system working conditions, nor will it reduce the power consumption due to the decrease in the number of operating cooling equipment in the system. That is, the cooling water flow of the entire cooling water system is always constant, regardless of the actual needs of the cooling equipment.

[0003] Since the cooling water pump has been continuously running at full load throughout the entire shipping cycle of the ship, it not only causes wear and tear of the cooling water pump itself and reduces its service life, but also indirectly causes waste of electric energy and fuel consumption for power generation. For example: The power of a cooling water pump group of a large container ship is 160 kW, and the cooling service objects are 30 cooling equipment. Assuming a voyage cycle of three months, without considering the oil-electric conversion efficiency, the fuel consumption for power generation using two cooling water pump groups will reach 12 tons. If this fuel consumption corresponds to the entire 20-year service life cycle of the ship, it will be an even more huge value. Therefore, it is necessary to develop a method and a system for reducing the energy consumption of a low-temperature cooling water system of a large ship to reduce energy consumption, save energy, and improve the shipping life of the ship.

[0004] Although some energy-saving ship cooling systems using variable-frequency pumps have been proposed in the prior art. For example, a ship central cooling system disclosed in Patent CN203358863U changes the pump speed by variable-frequency means, enabling the flow rate to change according to the magnitude of the system's heat load, achieving the purpose of energy-saving operation of the system. However, it is necessary to divide the cooling equipment into three groups, each connected to the cooling fresh water system through a self-acting valve. This not only makes the system structure complex, affecting applicability and implementation cost, but also the method of using conventional temperature parameters for variable-frequency control leads to problems of hysteresis and poor accuracy in the control process. Since the cooling power of the three groups of cooling equipment is not very different, this method is more suitable for the application of small ships. The low-temperature cooling water system of large ships has particularities. The low-temperature cooling water system of large ships is one of the most massive and equipment-intensive pipeline systems in the conventional systems of ships. Due to multiple stages in a shipping cycle, the number of operating cooling equipment and the cooling power consumption vary in each stage, with the characteristics of the lowest flow rate and a large range of flow rate changes. Therefore, the existing methods for reducing energy consumption or system structures of cooling systems cannot meet the application requirements of the low-temperature cooling water system of large ships. Summary of the Invention

[0005] The present invention aims to solve at least one of the above technical problems to some extent. The present invention provides a method and system for reducing the energy consumption of the low-temperature cooling water system of large ships, which can adapt to the characteristics of the lowest flow rate and a large range of flow rate changes in the low-temperature cooling water system of large ships, timely reduce the power consumption of the cooling water pump, achieve a significant reduction in energy consumption, and at the same time has the advantages of small implementation changes and strong applicability.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0007] A method for reducing the energy consumption of the low-temperature cooling water system of large ships, the method comprising:

[0008] Dividing the low-temperature cooling water system into a main engine cooling water subsystem and an auxiliary engine cooling water subsystem. The main engine cooling water subsystem is used to provide cooling services for the equipment related to the operation of the main engine, and the auxiliary engine cooling water subsystem is used to provide cooling services for the equipment related to the operation of the auxiliary engine. The low-temperature cooling water system is provided with a power source for the cooling water flow rate by a cooling water pump group with variable-frequency control;

[0009] When only the auxiliary engine cooling water subsystem needs to operate, isolate the main engine cooling water subsystem and control the cooling water pump group to operate with reduced power; when both the main engine cooling water subsystem and the auxiliary engine cooling water subsystem are in normal use, control the cooling water pump group to operate with variable frequency with the percentage of the main engine load as a variable factor.

[0010] Considering that the operating conditions and status of the main engine cooling water subsystem depend on the different navigation stages of the ship, in order to minimize the modifications to the low-temperature cooling water system and enhance its applicability, in the preferred technical solution, during different navigation stages of a large ship, the isolation valve is used to control the relative independence or system integration of the main engine cooling water subsystem and the auxiliary engine cooling water subsystem.

[0011] Considering that the main engine operating condition of a large ship in the berthing and anchoring state is that the main engine is not running, at this time the main engine cooling power consumption is zero, and correspondingly the cooling water flow demand for the main engine cooling equipment is also zero. In order to reduce the power consumption of the cooling water pump group by the cooling water flow related to the main engine, in the preferred technical solution, in the port mode when the large ship is in the berthing and anchoring state, the isolation valve is closed to isolate the main engine cooling water subsystem, so that the cooling water pump group provides cooling water flow for the auxiliary engine cooling water subsystem; when the large ship is in the navigation mode, the isolation valve is opened to integrate the main engine cooling water subsystem and the auxiliary engine cooling water subsystem.

[0012] Considering that the operating conditions and status of the main engine cooling water subsystem depend on the different navigation stages of the ship, in order to make the power consumption of the cooling water pump group change with the cooling water system flow demand, with high energy-saving efficiency and good economy, in the preferred technical solution, during different navigation stages of a large ship, the operation of the cooling water pump group is controlled by frequency conversion.

[0013] In the preferred technical solution, in the port mode when the large ship is in the berthing and anchoring state, the cooling water pump group is controlled to reduce power consumption with the set value of only meeting the cooling water flow of the auxiliary engine cooling water subsystem.

[0014] Considering that when a large ship is in the cruising state, due to the influence of the shipping cycle and the arrival time of the liner at the port, the main engine often operates with reduced power, and at this time the cooling water flow required for the cooling equipment related to the main engine also decreases accordingly; when the large ship is in the in-port and out-port state, the main engine power changes frequently and significantly, and at this time the cooling water flow required for the cooling equipment related to the main engine also changes frequently. In order to enable the power load of the cooling water pump group to be adjusted in real time and dynamically under different working conditions and further reduce the power consumption in a timely manner, in the preferred technical solution, when the large ship is in the navigation mode, the cooling water pump group is controlled by real-time frequency conversion to operate with the main engine load percentage as the variable factor.

[0015] In the preferred technical solution, the navigation mode of the large ship includes the cruising and in-port and out-port states.

[0016] In order to further achieve a significant reduction in energy consumption, in a preferred technical solution, the cooling water pump group includes multiple parallel cooling water pumps, and the power reduction operation of the cooling water pump group includes shutting down one or more cooling water pumps. For example, when the auxiliary engine cooling water subsystem operates independently, only one cooling water pump needs to operate, and there is no need for frequency conversion control to achieve this.

[0017] Considering that the cooling power of the main engine air cooler and the required cooling water flow rate of a large ship account for a large proportion in the entire ship's low-temperature cooling water system, in order to make the effect and economy of reducing energy consumption in the cooling water system of a large ship more significant, in a preferred technical solution, the cooling water pump group includes multiple parallel cooling water pumps. The minimum value of the frequency conversion control range of the cooling water pump group is the power value corresponding to the cooling water flow rate required for the normal operation of the auxiliary engine cooling water subsystem, and the maximum value of the frequency conversion control range of the cooling water pump group is the power value corresponding to the cooling water flow rate when multiple cooling water pumps operate at full load.

[0018] A system for reducing the energy consumption of the low-temperature cooling water system of a large ship includes a low-temperature cooling water system, and the low-temperature cooling water system includes a main engine cooling water subsystem, an auxiliary engine cooling water subsystem, an isolation valve, and a cooling water pump group;

[0019] The main engine cooling water subsystem is used to provide cooling services for the equipment related to the operation of the main engine;

[0020] The auxiliary engine cooling water subsystem is used to provide cooling services for the equipment related to the operation of the auxiliary engine;

[0021] The isolation valve is used to open and close to control the relative independence or system integration of the main engine cooling water subsystem and the auxiliary engine cooling water subsystem;

[0022] The low-temperature cooling water system is provided with a power source for the cooling water flow rate by a cooling water pump group with frequency conversion control;

[0023] The low-temperature cooling water system operates based on the method for reducing the energy consumption of the low-temperature cooling water system of a large ship described in any one of the above.

[0024] In a preferred technical solution, it includes a shunt pipeline. The inlet end of the shunt pipeline is connected to the cooling water pump group, and the two outlet ends of the shunt pipeline are respectively connected to the main engine cooling water subsystem and the auxiliary engine cooling water subsystem. The isolation valve is arranged at the outlet end of the shunt pipeline connecting the main engine cooling water subsystem.

[0025] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0026] (1) The method of the present invention divides the low-temperature cooling water system into a main engine cooling water subsystem and an auxiliary engine cooling water subsystem. When only the auxiliary engine cooling water subsystem needs to operate, the main engine cooling water subsystem is isolated, and the cooling water pump group is controlled to operate with reduced power. When both the main engine cooling water subsystem and the auxiliary engine cooling water subsystem are in normal use, the cooling water pump group is controlled to operate with frequency conversion with the main engine load percentage as a variable factor, which can adapt to the characteristics of the low-temperature cooling water system of large ships with a minimum flow rate and a large flow rate variation range, has a high energy-saving efficiency, a wide coverage range, and can meet the dynamic adjustment of reducing the power of the low-temperature cooling water pump group at all stages of the full voyage of large ships, realizing the economic and efficient operation of the cooling water system, achieving the purpose of reducing energy consumption, and indirectly reducing the emission of exhaust gas by saving fuel oil for power generation, making the ship operation more friendly to the environment.

[0027] (2) The method and system of the present invention adopt, at different navigation stages of large ships, to control the relative independence or system integration of the main engine cooling water subsystem and the auxiliary engine cooling water subsystem through isolation valves. The operation is simple, and the power consumption of the cooling water pump group by the main engine-related cooling equipment can be reduced. Especially at the two navigation stages of anchoring and berthing, one or more cooling water pumps can be shut down for power reduction use without frequency conversion control, directly saving more than 50% of the original power consumption.

[0028] (3) The system structure of the present invention is relatively simple. Only one isolation valve is needed to isolate the cooling water flow of the main engine-related cooling equipment, which can better meet the needs of different ship types for the structural adjustment of the low-temperature cooling water system, without changing the original system principle, and has the advantages of small implementation changes, strong versatility, and wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0030] Figure 1 is a schematic structural diagram of the low-temperature cooling water system of the present invention;

[0031] Figure 2 is a schematic structural diagram of the main engine cooling water subsystem of the present invention;

[0032] Figure 3 is a schematic structural diagram of the auxiliary engine cooling water subsystem of the present invention.

[0033] Reference numerals in the drawings: main engine cooling water subsystem 1, No. 1 stern tube lubricating oil cooler 101, No. 2 stern tube lubricating oil cooler 102, No. 1 intermediate bearing 103, No. 2 intermediate bearing 104, main engine MGO cooler 105, main engine air cooler 106, main engine cylinder jacket water cooler 107, No. 1 main engine lubricating oil cooler 108, No. 2 main engine lubricating oil cooler 109;

[0034] Auxiliary engine cooling water subsystem 2, cab air conditioner 201, galley unit air conditioner 202, No. 1 air conditioner unit 203, No. 2 air conditioner unit 204, No. 1 refrigeration unit 205, No. 2 refrigeration unit 206, No. 2 transformer 207, machine repair shop air conditioner 208, steam condenser 209, No. 1 main transformer 210, No. 2 central control room air conditioner 211, No. 1 main switchboard air conditioner 212, No. 2 main switchboard air conditioner 213, No. 1 central control room air conditioner 214, No. 1 air compressor 215, No. 2 air compressor 216, No. 3 air compressor 217, generator MGO cooler 218, boiler MGO cooler 219, generator cylinder block 220;

[0035] Cooling water pump group 3, cooling water pump 301, main seawater pipe 4, main seawater pump 5, central cooler 6, isolation valve 7, shunt pipeline 8, unlabeled arrows indicate the flow direction. Detailed implementation manners

[0036] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0037] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by terms such as "import", "export", "front", "rear", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. In the description of the present invention, the meanings of "a plurality" and "several" are two or more, unless otherwise specifically defined.

[0038] In the present invention, unless otherwise clearly defined and limited, terms such as "connected", "connected to", "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0039] Embodiment 1:

[0040] In view of the problem that the cooling water pump 301, which is the most energy-consuming device in the entire low-temperature cooling water system of large ships in the prior art, is always in a state of full load, full power, and continuous operation, resulting in wear of the pump itself, waste of electric energy and fuel consumption for power generation, and considering the characteristics of the large ship low-temperature cooling water system with a large minimum flow rate and a large range of flow rate changes, and the fact that the existing energy-saving methods or systems of the cooling system cannot meet the application requirements of the large ship low-temperature cooling water system. Considering that the large ship low-temperature cooling water system is one of the most massive and equipment-intensive conventional pipeline systems in the ship's affiliated systems, usually a low-temperature cooling water system needs to meet the cooling water flow required by more than 30 cooling devices, and the corresponding cooling water flow required by the low-temperature cooling water system varies greatly. A preferred embodiment of the method for reducing the energy consumption of the large ship low-temperature cooling water system of the present invention includes:

[0041] Divide the low-temperature cooling water system into a main engine cooling water subsystem 1 and an auxiliary engine cooling water subsystem 2. The main engine cooling water subsystem 1 is used to provide cooling services for the equipment related to the operation of the main engine, and the auxiliary engine cooling water subsystem 2 is used to provide cooling services for the equipment related to the operation of the auxiliary engine. The low-temperature cooling water system is provided with a power source for cooling water flow by a cooling water pump group 3 with variable frequency control;

[0042] When only the auxiliary engine cooling water subsystem 2 needs to operate, isolate the main engine cooling water subsystem 1 and control the cooling water pump group 3 to operate with reduced power. When both the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2 are in normal use, control the cooling water pump group 3 to operate with variable frequency with the main engine load percentage as a variable factor.

[0043] For example: such as Figures 1 to 3As shown in the figure, the cooling equipment in the low-temperature cooling water system is classified into two categories according to the main engine and auxiliary engines, and each category forms a relatively independent cooling water subsystem. One is the main engine cooling water subsystem 1, which provides cooling services for equipment related to the operation of the main engine, such as the No. 1 stern tube lubricating oil cooler 101, the No. 2 stern tube lubricating oil cooler 102, the No. 1 intermediate bearing 103, the No. 2 intermediate bearing 104, the main engine MGO cooler 105, the main engine air cooler 106, the main engine cylinder jacket water cooler 107, the No. 1 main engine lubricating oil cooler 108, and the No. 2 main engine lubricating oil cooler 109. The main seawater pump 5 can supply seawater from the main seawater pipe 4, and under the action of the central cooler 6, the cooling water pump group 3 can provide a circulating cooling water flow to each piece of equipment related to the operation of the main engine. The other is the auxiliary engine cooling water subsystem 2, which provides cooling services for equipment related to the operation of auxiliary engines, such as the cab air conditioner 201, the galley unit air conditioner 202, the No. 1 air conditioner unit 203, the No. 2 air conditioner unit 204, the No. 1 refrigeration unit 205, the No. 2 refrigeration unit 206, the No. 2 transformer 207, the machine repair shop air conditioner 208, the steam condenser 209, the No. 1 main transformer 210, the No. 2 centralized control room air conditioner 211, the No. 1 main switchboard air conditioner 212, the No. 2 main switchboard air conditioner 213, the No. 1 centralized control room air conditioner 214, the No. 2 main switchboard air conditioner 213, the No. 1 air compressor 215, the No. 2 air compressor 216, the No. 3 air compressor 217, the generator MGO cooler 218, the boiler MGO cooler 219, and the generator cylinder block 220. The main seawater pump 5 can supply seawater from the main seawater pipe 4, and under the action of the central cooler 6, the cooling water pump group 3 can provide a circulating cooling water flow to each piece of equipment related to the operation of the auxiliary engine. According to the operating states of the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2 during the ship's voyage, the relative independence or system integration of the two types of cooling water subsystems can be controlled.

[0044] Since the cooling water pump group 3 is the largest energy-consuming equipment in the entire low-temperature cooling water system, when only the auxiliary engine cooling water subsystem 2 needs to operate, the main engine cooling water subsystem 1 can be isolated. That is, when the cooling water pump group 3 supplies cooling water flow to the auxiliary engine cooling water subsystem 2 alone, the cooling water flow related to the main engine can be isolated, reducing its consumption of the power of the cooling water pump group 3. The power of the cooling water pump group 3 can be controlled to operate at a reduced power, and the power of the cooling water pump group 3 only needs to meet the cooling water flow required for cooling the equipment related to the auxiliary engine, achieving the purpose of reducing the power operation of the cooling water pump group 3.

[0045] When both the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2 are in normal use, the main engine power changes frequently and significantly. At this time, the cooling water flow required by the cooling equipment related to the main engine also changes frequently. When the cooling water pump group 3 supplies cooling water flow to both the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2 simultaneously, controlling the cooling water pump group 3 to operate with variable frequency using the main engine load percentage as a variable factor can enable the cooling water pump group 3 to be controlled by frequency conversion, so that its flow rate changes with the change of the main engine power. Compared with the existing conventional methods such as temperature parameter variable frequency control, the power load of the cooling water pump 301 can be adjusted timely and dynamically under different working conditions, thus adapting to the characteristics of the large ship low-temperature cooling water system with the lowest flow rate and large flow rate change range. Since the cooling power of the main engine air cooler 106 and the required cooling water flow rate of the large ship account for a large proportion in the whole ship's low-temperature cooling water system, this method is more effective and economical in reducing the energy consumption of the large ship's low-temperature cooling water system. It can not only improve the energy-saving efficiency and economy of large ships, but also indirectly reduce the exhaust gas emissions by saving fuel oil for power generation, making the ship operation more friendly to the environment. It is widely applicable to various civil ships such as large and medium-sized container ships, LNG ships, LPG ships, chemical tankers, ro-ro ships, floating storage tankers, product oil tankers, crude oil tankers, and bulk carriers.

[0046] Considering that the operating conditions and states of the main engine cooling water subsystem 1 depend on the different navigation stages of the ship, in order to make the modification of the low-temperature cooling water system small and the applicability strong, further, in different navigation stages of large ships, the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2 are controlled to be relatively independent or system integrated through the isolation valve 7; for example: when the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2 are connected in parallel to the cooling water pump group 3, the isolation valve 7 is set on the main engine cooling water subsystem 1, then only one manual isolation valve 7 is needed to isolate the main engine cooling water subsystem 1, or the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2 can be used simultaneously, which can simplify the system structure and the implementation cost is low.

[0047] Considering that the main engine operating condition of a large ship in the mooring or anchoring state is that the main engine is not running, at this time the cooling power consumption of the main engine is zero, and correspondingly the cooling water flow demand for the main engine cooling equipment is also zero. To reduce the power consumption of the cooling water flow related to the main engine on the cooling water pump set 3, further, taking an ordinary voyage as an example, a voyage is now split into four different stages, namely the in-port / out-port, cruising, anchoring, and mooring stages. When the large ship is in the port mode of the mooring or anchoring state, the main engine is not running. At this time, the power consumption of the main engine related cooling equipment is zero, and the corresponding cooling water flow is also zero, that is, there is no need to provide cooling water flow for the main engine related cooling equipment. At this time, the isolation valve 7 is closed to isolate the main engine cooling water subsystem 1, so that the cooling water pump set 3 only provides cooling water flow for the auxiliary engine cooling water subsystem 2, and forms a relatively independent cooling water flow circulation of the auxiliary engine cooling water subsystem 2; when the large ship is in the navigation mode of the in-port / out-port and cruising states, the isolation valve 7 is opened to integrate the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2. For example: the isolation valve 7 is fully opened, and the cooling water pump set 3 provides cooling water flow, forming a cooling water flow circulation of the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2.

[0048] Considering that the operating condition change and state of the main engine cooling water subsystem 1 depend on the different navigation stages of the ship, in order to make the power consumption of the cooling water pump set 3 change with the change of the cooling water system flow demand, with the characteristics of high energy consumption reduction efficiency and good economy, further, in different navigation stages of the large ship, the cooling water pump set 3 is controlled to operate by frequency conversion.

[0049] Further, when the large ship is in the port mode of the mooring or anchoring state, the main engine cooling water subsystem 1 is isolated, and the cooling water pump set 3 is controlled to reduce power consumption with only the cooling water flow of the auxiliary engine cooling water subsystem 2 as the set value, so as to achieve the purpose of reducing energy consumption.

[0050] In order to further achieve a significant reduction in energy consumption, further, the cooling water pump group 3 includes multiple parallel cooling water pumps 301. The power reduction operation of the cooling water pump group 3 includes shutting down one or more cooling water pumps 301. For example, the cooling water pump group 3 includes three parallel cooling water pumps 301. When the auxiliary engine cooling water subsystem 2 operates independently, the flow rate of the auxiliary engine cooling water subsystem 2 is 547.52 m3 / h. Only one cooling water pump 301 needs to operate, and the corresponding single-pump power is 120 KW. Without frequency conversion control, it can meet the flow circulation requirements of the auxiliary engine cooling water subsystem 2 and satisfy the operation of the cooling water system in the two stages of ship anchoring and berthing. Compared with the overall operating conditions of the original low-temperature cooling water system, the required cooling water pumps 301 are 2, and the power consumption for continuous full-power and full-load operation is 2×160 KW / h. It can save 200 KW of power. The fuel consumption of the generator for this ship type is 186 g / kWh. Calculated based on 30 days of anchoring and berthing time in a year, 27 tons of fuel can be saved.

[0051] Considering that when a large ship is in the cruising state, due to the influence of the shipping cycle and the arrival time of the liner, the main engine often has the situation of power reduction, and at this time, the cooling water flow required by the cooling equipment related to the main engine also decreases accordingly; when a large ship is in the state of entering and leaving the port, the power of the main engine changes frequently and the change range is large. At this time, the cooling water flow required by the cooling equipment related to the main engine also changes frequently. In order to enable the power load of the cooling water pump group 3 to be adjusted in real time and dynamically under different working conditions, and further reduce the power consumption in a timely manner, further, when the large ship is in the navigation mode, the cooling water pump group 3 is controlled by frequency conversion in real time and operates with the main engine load percentage as the variable factor. For example, when the large ship is in the cruising and entering / leaving port states, the isolation valve 7 is fully opened, and the low-temperature cooling water system operates normally. The power of the cooling water pump group 3 is changed by frequency conversion with the change of the main engine load, so as to adapt to the flow change of the low-temperature cooling water system in different navigation stages, and achieve the purpose of timely reducing the power of the cooling water pump group 3 and reducing energy consumption.

[0052] Considering that the cooling power of the main engine air cooler 106 of a large ship and the required cooling water flow rate account for a large proportion in the entire ship's low-temperature cooling water system, in order to make the effect of reducing energy consumption and the economy of the cooling water system of a large ship more significant, further, the cooling water pump group 3 includes multiple parallel cooling water pumps 301. The minimum value of the frequency conversion control range of the cooling water pump group 3 is the power value of the cooling water flow rate required for the normal operation of the auxiliary engine cooling water subsystem 2, and the maximum value of the frequency conversion control range of the cooling water pump group 3 is the power value corresponding to the cooling water flow rate when multiple cooling water pumps 301 operate at full load. For example, the cooling water pump group 3 includes three parallel cooling water pumps 301. When the large ship is at anchor or in port, the isolation valve 7 is closed, and only one cooling water pump 301 needs to operate, with a power of 120 kW. When the large ship is in cruising or entering / leaving port, the isolation valve 7 is fully opened. According to the flow rate / power curve of the cooling water pump 301 in this embodiment, the minimum value of the frequency conversion control range of the cooling water pump group 3 is the power value of the cooling water flow rate of the auxiliary engine cooling water subsystem 2 plus the cooling water flow rate required by the main engine at the minimum load percentage, which is 140 kW. The maximum value of the frequency conversion control range of the cooling water pump group 3 is the power value corresponding to the cooling water flow rate when two cooling water pumps 301 operate at full load, which is 320 kW. Therefore, the frequency conversion power range of the cooling water pump group 3 corresponding to this ship type is 120 kW to 320 kW. Within this range, the low-temperature cooling water system operates as a whole and reduces power consumption following the change of the main engine load.

[0053] Embodiment 2:

[0054] A preferred embodiment of the system for reducing the energy consumption of the low-temperature cooling water system of a large ship according to the present invention. The system for reducing the energy consumption of the low-temperature cooling water system of a large ship includes a low-temperature cooling water system, and the low-temperature cooling water system includes a main engine cooling water subsystem 1, an auxiliary engine cooling water subsystem 2, an isolation valve 7, and a cooling water pump group 3;

[0055] The main engine cooling water subsystem 1 is used to provide cooling services for the equipment related to the operation of the main engine;

[0056] The auxiliary engine cooling water subsystem 2 is used to provide cooling services for the equipment related to the operation of the auxiliary engine;

[0057] The isolation valve 7 is used to open and close to control the relative independence or system integration of the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2;

[0058] The low-temperature cooling water system is provided with a power source for the cooling water flow rate by a cooling water pump group 3 with frequency conversion control;

[0059] The low-temperature cooling water system operates based on the method for reducing the energy consumption of the low-temperature cooling water system of a large ship described in Embodiment 1.

[0060] Further, it includes a shunt pipeline 8. The inlet end of the shunt pipeline 8 is connected to the cooling water pump group 3. The two outlet ends of the shunt pipeline 8 are respectively connected to the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2. The isolation valve 7 is arranged at the outlet end of the shunt pipeline 8 connected to the main engine cooling water subsystem 1.

[0061] For example: As Figures 1 to 3 shown, the main seawater pipe 4 is connected to the main seawater pump 5. The main seawater pump 5 is connected to the central cooler 6. The central cooler 6 is connected to the cooling water pump group 3. The cooling water pump group 3 includes three parallel cooling water pumps 301. The cooling water pump group 3 is connected to the inlet end of the shunt pipeline 8. Each main engine-related device of the main engine cooling water subsystem 1 is connected to one outlet of the shunt pipeline 8, and the isolation valve 7 is arranged at this outlet. The return pipeline of each main engine-related device is connected to the central cooler 6 to form an independent low-temperature cooling water cycle to cool the devices related to the operation of the main engine; each auxiliary engine-related device of the auxiliary engine cooling water subsystem 2 is connected to the other outlet of the shunt pipeline 8, and the return pipeline of each auxiliary engine-related device is connected to the central cooler 6 to form another independent low-temperature cooling water cycle to cool the devices related to the operation of other auxiliary engines except the main engine; then the cooling devices belonging to the classification system can be classified to apply to different navigation stages, corresponding to two usage modes:

[0062] One is when the ship is in the port mode, that is, the main engine stops running and the isolation valve 7 is closed. The auxiliary engine cooling water subsystem 2 can operate independently. The cooling water pump group 3 reduces power consumption by means such as frequency conversion or shutting down one or more cooling water pumps 301 to only meet the set value of the cooling water flow of the auxiliary engine cooling water subsystem 2 and reduce power consumption to achieve the purpose of energy saving; the other is when the ship is in the navigation mode, that is, when the main engine and the auxiliary engine-related devices are running simultaneously, the isolation valve 7 is fully open, and a complete low-temperature cooling water system running as a whole can be formed. At this time, the cooling water pump group 3 takes the percentage change of the main engine load as a variable factor and takes the cooling water flow required for the normal operation of the auxiliary engine cooling equipment as the lowest set value. By controlling the frequency conversion of the cooling water pump group 3, its power changes with the main engine load, so as to reduce the power of the cooling water pump 301, and further enable the cooling water pump group 3 to adjust the power according to the change of the flow requirements of the main engine cooling water subsystem 1 and the auxiliary engine cooling water subsystem 2. The power consumption of the cooling water pump group 3 corresponds to the change of the actual low-temperature cooling water system flow demand and is adjusted in real time to achieve the purpose of energy saving. With only one isolation valve 7, the cooling water flow of the cooling equipment related to the main engine can be isolated. Therefore, the overall design structure of the system is simple, the operation is convenient, and the power consumption reduction is remarkable. It can be applied to the energy-saving design of the low-temperature cooling water system of each large ship and can better meet the needs of different ship types for the structural adjustment of the low-temperature cooling water system.

[0063] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for reducing the energy consumption of the low-temperature cooling water system of large ships, characterized in that, The method includes: Dividing the low-temperature cooling water system into a main engine cooling water subsystem (1) and an auxiliary engine cooling water subsystem (2), where the main engine cooling water subsystem (1) is used to provide cooling services for equipment related to the operation of the main engine, the auxiliary engine cooling water subsystem (2) is used to provide cooling services for equipment related to the operation of the auxiliary engine, and the low-temperature cooling water system is provided with a power source for the cooling water flow by a cooling water pump group (3) with frequency conversion control; When only the auxiliary engine cooling water subsystem (2) needs to operate, isolate the main engine cooling water subsystem (1) and control the cooling water pump group (3) to operate with reduced power; when both the main engine cooling water subsystem (1) and the auxiliary engine cooling water subsystem (2) are in normal use, control the cooling water pump group (3) to operate with frequency conversion with the main engine load percentage as a variable factor.

2. A method for reducing the energy consumption of the low-temperature cooling water system of a large ship according to claim 1, characterized in that, At different navigation stages of a large ship, control the relative independence or system integration of the main engine cooling water subsystem (1) and the auxiliary engine cooling water subsystem (2) through an isolation valve (7).

3. A method for reducing the energy consumption of the low-temperature cooling water system of a large ship according to claim 2, characterized in that, In the port mode when the large ship is in the mooring or anchoring state, close the isolation valve (7) to isolate the main engine cooling water subsystem (1), so that the cooling water pump group (3) provides cooling water flow for the auxiliary engine cooling water subsystem (2); when the large ship is in the navigation mode, open the isolation valve (7) to integrate the main engine cooling water subsystem (1) and the auxiliary engine cooling water subsystem (2).

4. A method for reducing the energy consumption of the low-temperature cooling water system of a large ship according to claim 1, characterized in that, At different navigation stages of a large ship, control the operation of the cooling water pump group (3) through frequency conversion.

5. A method for reducing the energy consumption of the low-temperature cooling water system of a large ship according to claim 4, characterized in that, In the port mode when the large ship is in the mooring or anchoring state, control the cooling water pump group (3) to operate with reduced power with the set value of only meeting the cooling water flow of the auxiliary engine cooling water subsystem (2).

6. A method for reducing the energy consumption of the low-temperature cooling water system of a large ship according to claim 4, characterized in that, When the large ship is in the navigation mode, control the cooling water pump group (3) to operate with frequency conversion in real time with the main engine load percentage as a variable factor.

7. A method for reducing the energy consumption of the low-temperature cooling water system of a large ship according to claim 1, characterized in that The cooling water pump group (3) includes multiple parallel cooling water pumps (301), and the cooling water pump group (3) operating with reduced power includes shutting down one or more cooling water pumps (301).

8. A method for reducing the energy consumption of the low-temperature cooling water system of a large ship according to claim 1, characterized in that, The cooling water pump group (3) includes multiple parallel cooling water pumps (301), the minimum value of the frequency conversion control range of the cooling water pump group (3) is the power value of the cooling water flow required for the normal operation of the auxiliary engine cooling water subsystem (2), and the maximum value of the frequency conversion control range of the cooling water pump group (3) is the power value corresponding to the cooling water flow when multiple cooling water pumps (301) operate at full load.

9. A system for reducing the energy consumption of the low-temperature cooling water system of a large ship, including a low-temperature cooling water system, characterized in that, The low-temperature cooling water system includes a main engine cooling water subsystem (1), an auxiliary engine cooling water subsystem (2), an isolation valve (7), and a cooling water pump group (3). The low-temperature cooling water system operates based on the method for reducing the energy consumption of the low-temperature cooling water system of a large ship according to any one of claims 1 to 8, and the isolation valve (7) is used to open and close to control the relative independence or system integration of the main engine cooling water subsystem (1) and the auxiliary engine cooling water subsystem (2).

10. The system for reducing the energy consumption of the low-temperature cooling water system of large ships according to claim 9, characterized in that, It includes a diversion pipeline (8), the inlet end of the diversion pipeline (8) is connected to the cooling water pump group (3), the two outlet ends of the diversion pipeline (8) are respectively connected to the main engine cooling water subsystem (1) and the auxiliary engine cooling water subsystem (2), and the isolation valve (7) is arranged at the outlet end of the diversion pipeline (8) connected to the main engine cooling water subsystem (1).

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