Water production system

Abstract

To provide a water production system that can effectively use waste heat from scavenging air cooling water for desalination of seawater in a water production device.SOLUTION: A water production system 100 comprises: a water production device 1 equipped with a heater 2 and a steam condenser 3; a steam cooling water supply line L6 for supplying steam cooling water to the steam condenser 3; a raw water supply line L4 for supplying a part of the steam cooling water used to cool steam in the steam condenser 3 to the heater 2; a temperature sensor 6 for measuring the temperature of seawater supplied to the steam condenser 3 as steam cooling water; and a scavenging air cooling water supply line L2 for supplying the seawater to a scavenging air cooler 14 as scavenging air cooling water for cooling scavenging air. When the seawater temperature measured by a temperature sensor 6 is below the predetermined temperature, a part of the scavenging air cooling water used for cooling scavenging air in the scavenging air cooler 14 is supplied to a heater 2 as raw material water.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a freshwater production system for desalination of seawater, and more particularly to a freshwater production system that utilizes waste heat from an internal combustion engine such as a diesel engine that is the main engine of a ship. [Background technology]

[0002] In ships, it has been conventional to produce fresh water from seawater by utilizing waste heat from an internal combustion engine such as a diesel engine mounted on the ship. For example, in Patent Document 1, scavenging air cooling water whose temperature has been increased by being used to cool scavenging air supplied to the diesel engine is supplied to a fresh water generator, and the waste heat of the scavenging air cooling water is used as a heat source for evaporating seawater in the fresh water generator. In the fresh water generator, seawater is heated and evaporated in a heater by heat exchange with the scavenging air cooling water, and then the steam generated by evaporation is cooled and condensed in a condenser to desalinate the seawater. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4409546 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the temperature of the scavenging air cooling water used to cool the scavenging air is approximately 60°C when the scavenging air cooling water is fresh water, whereas the temperature is approximately 45°C to 50°C when the scavenging air cooling water is seawater, which is lower than the temperature of fresh water. In freshwater generators, seawater is evaporated under reduced pressure, and the evaporation temperature of seawater is generally approximately 55°C to 60°C. Therefore, if the waste heat of the scavenging air cooling water, which is approximately 45°C to 60°C, is used as the main heat source for evaporating seawater in freshwater generators, the amount of heat required to produce a sufficient amount of steam is insufficient, resulting in a decrease in the amount of freshwater produced. This can lead to problems such as a decrease in the freshwater production performance of the freshwater generator, or a larger heat transfer area is required for heat exchange between the seawater and the scavenging air cooling water to produce a sufficient amount of freshwater, resulting in an increase in the size of the freshwater generator. Thus, it is not practical to use the waste heat of the scavenging air cooling water as the main heat source for evaporating seawater in freshwater generators.

[0005] The present invention has been made with a view to solving the above-mentioned problems, and an object of the present invention is to provide a fresh water production system that can effectively utilize the waste heat of scavenging air cooling water for desalination of seawater in a fresh water production system. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention is directed to a fresh water production system as described in item 1 below.

[0007] Item 1. A water production system for desalination of seawater on a ship, a freshwater generator including a heater to which seawater is supplied as raw water and which heats and evaporates the raw water, and a condenser to which seawater is supplied as steam cooling water and which cools and condenses steam generated by evaporation of the raw water using the steam cooling water; a steam cooling water supply line for supplying steam cooling water to the condenser; a raw water supply line for supplying at least a portion of the steam cooling water used to cool the steam in the condenser to the heater; a temperature sensor for measuring the temperature of seawater supplied to the condenser as steam cooling water; a scavenging air cooling water supply line for supplying seawater to a scavenging air cooler as scavenging air cooling water for cooling scavenging air supplied to the marine internal combustion engine; Equipped with a fresh water production system configured to mix at least a part of scavenging air cooling water used for cooling the scavenging air in the scavenging air cooler with seawater supplied to the condenser as steam cooling water from the scavenging air cooling water supply line, or to supply the seawater as raw water to the heater, when the seawater temperature measured by the temperature sensor is lower than a predetermined temperature.

[0008] Furthermore, the fresh water production system of the present invention encompasses the fresh water production system described in the following item 2 as a preferred embodiment of the fresh water production system described in the above item 1.

[0009] Item 2. A second raw water supply line connected to the scavenging air cooling water supply line and for supplying at least a portion of the scavenging air cooling water used to cool the scavenging air to the heater or for mixing it with the raw water supply line; a first flow rate regulating valve that regulates the flow rate of the steam cooling water flowing through the raw water supply line; a second flow rate control valve that adjusts the flow rate of scavenging air cooling water flowing through the second raw water supply line; Item 1. The fresh water production system according to item 1, further comprising: a control device that controls the first flow rate adjustment valve and the second flow rate adjustment valve based on the seawater temperature measured by the temperature sensor.

[0010] Furthermore, the fresh water production system of the present invention encompasses the fresh water production system described in the following item 3 as a preferred embodiment of the fresh water production system described in the above item 2.

[0011] Item 3. The second raw water supply line supplies at least a portion of the scavenging air cooling water used to cool the scavenging air to the heater; Item 3. The freshwater production system according to Item 2, wherein the control device controls the first flow control valve and the second flow control valve so as to close the first flow control valve and open the second flow control valve when the seawater temperature measured by the temperature sensor is lower than a predetermined temperature, and to open the first flow control valve and close the second flow control valve when the seawater temperature measured by the temperature sensor is higher than the predetermined temperature.

[0012] Furthermore, the fresh water production system of the present invention encompasses the fresh water production system described in the following item 4 as a preferred embodiment of the fresh water production system described in the above item 1.

[0013] Item 4. A scavenging air cooling water supply line connected to the scavenging air cooling water supply line for mixing at least a portion of the scavenging air cooling water used to cool the scavenging air with seawater supplied to the condenser as steam cooling water; a flow rate regulating valve for regulating the flow rate of the scavenging air cooling water flowing through the scavenging air cooling water supply line; Item 1. The fresh water production system according to item 1, further comprising: a control device that controls the flow rate regulating valve based on the seawater temperature measured by the temperature sensor.

[0014] Furthermore, the fresh water production system of the present invention encompasses the fresh water production system described in the following item 5 as a preferred embodiment of the fresh water production system described in items 1 to 4 above.

[0015] Item 5. The fresh water production system according to any one of Items 1 to 4, wherein the heater is configured to heat the raw water with jacket cooling water used to cool the internal combustion engine. [Effects of the Invention]

[0016] According to the fresh water production system of the present invention, the waste heat of the scavenging air cooling water can be effectively utilized for desalination of seawater in the fresh water production apparatus, and the fresh water production performance of the fresh water production apparatus can be improved. [Brief explanation of the drawings]

[0017] [Figure 1]1 is a schematic configuration diagram of a fresh water production system according to an embodiment of the present invention. [Figure 2] FIG. 10 is a schematic configuration diagram of a fresh water production system according to another embodiment of the present invention. [Figure 3] FIG. 10 is a schematic configuration diagram of a fresh water production system according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention relates to a freshwater production system that utilizes waste heat from an internal combustion engine, which is a main engine for generating propulsion power in a ship, to desalinate seawater in the freshwater production system, thereby improving the performance of the freshwater production system. The internal combustion engine is, for example, a diesel engine.

[0019] 1 is a schematic configuration diagram of a freshwater production system 100 according to one embodiment of the present invention. The freshwater production system 100 includes at least a freshwater generator 1, a steam cooling water supply line L6 for supplying seawater as steam cooling water to a condenser 3 of the freshwater generator 1, a raw water supply line L4 for supplying at least a portion of the steam cooling water used to cool the steam in the condenser 3 to a heater 2 of the freshwater generator 1 as raw water, a temperature sensor 6 for measuring the temperature of the seawater supplied to the condenser 3 as steam cooling water, a scavenging air cooling water supply line L2 for supplying seawater to a scavenging air cooler 14 as scavenging air cooling water for cooling scavenging air supplied to a diesel engine 10 as an internal combustion engine for a marine vessel, and a second raw water supply line L5 connected to the scavenging air cooling water supply line L2 and for supplying at least a portion of the scavenging air cooling water used to cool the scavenging air in the scavenging air cooler 14 to the heater 2 as raw water.

[0020] The diesel engine 10 is an internal combustion engine that uses at least one of fuel oil and fuel gas as a main fuel and burns the main fuel together with scavenging air.

[0021] The jacket cooling water supply line L1 is a pipe through which jacket cooling water flows in order to supply cooling water for cooling the diesel engine 10 (referred to as "jacket cooling water" in this disclosure) to the diesel engine 10. The jacket cooling water circulates through the jacket cooling water supply line L1 by driving a pump 15.

[0022] The flow rate of the jacket cooling water supplied to the diesel engine 10 is adjusted by a flow rate adjustment valve 16. The flow rate adjustment valve 16 may be equipped with a flow meter. A cooler 17 is connected to the jacket cooling water supply line L1. The cooler 17 cools the jacket cooling water whose temperature has increased after being used to cool the diesel engine 10. The cooler 17 is, for example, a heat exchanger, and is supplied with cooling fluid from a central cooler. In the cooler 17, the jacket cooling water is cooled by heat exchange with the cooling fluid.

[0023] A heating fluid supply line L3 is connected to the jacket cooling water supply line L1 using, for example, a pipe joint. The heating fluid supply line L3 is a pipe through which jacket cooling water flows in order to supply a portion of the jacket cooling water, which has become hot as a result of cooling the diesel engine 10, to the heater 2 of the fresh water generator 1. A portion of the jacket cooling water, which has become hot as a result of cooling the diesel engine 10, is used as a heating fluid for heating seawater, which serves as raw water, in the heater 2 of the fresh water generator 1. A portion of the jacket cooling water is diverted from the jacket cooling water supply line L1 to the heating fluid supply line L3, passes through the heater 2 of the fresh water generator 1, and then returns to the jacket cooling water supply line L1.

[0024] A temperature sensor 18 is connected to the heating fluid supply line L3. The temperature sensor 18 measures the temperature of the jacket cooling water that is diverted from the jacket cooling water supply line L1 to the heating fluid supply line L3 and supplied to the heater 2 of the fresh water generator 1. A conventionally known temperature sensor can be used as the temperature sensor 18. The detection result by the temperature sensor 18 is preferably monitored by a control device.

[0025] The flow rate of the jacket cooling water supplied to the heater 2 of the fresh water generator 1 through the heating fluid supply line L3 is adjusted by a flow rate adjustment valve 19. The opening / closing and opening degree of the flow rate adjustment valve 19 are preferably controlled by a control device. The flow rate of the jacket cooling water supplied to the heater 2 of the fresh water generator 1 through the heating fluid supply line L3 is preferably adjusted by the control device based on the temperature of the jacket cooling water detected by a temperature sensor 18. The flow rate adjustment valve 19 may be equipped with a flow meter, and the detection results by the flow meter may be monitored by a control device described later.

[0026] The turbocharger 11 supplies scavenging air to the diesel engine 10. The turbocharger 11 includes a turbine 12 driven by exhaust gas emitted when the diesel engine 10 combusts main fuel, and a compressor 13 that compresses outside air using the rotational power of the turbine 12. The turbocharger 11 supplies the compressed outside air to the diesel engine 10 as scavenging air.

[0027] The scavenging air cooler 14 cools the scavenging air supplied from the turbocharger 11 to the diesel engine 10. Since the scavenging air is adiabatically compressed and has a high temperature, it is cooled in the scavenging air cooler 14 before being supplied to the diesel engine 10 for purposes such as increasing the air density (weight per unit volume). The scavenging air cooler 14 is, for example, a heat exchanger.

[0028] The scavenging air cooling water supply line L2 is a pipe through which scavenging air cooling water flows in order to supply cooling water for cooling scavenging air (referred to as "scavenging air cooling water" in this disclosure). Seawater that is pumped from the sea by a seawater pump and taken into the ship is used as the scavenging air cooling water. The seawater pumped by the seawater pump is supplied to various seawater-using locations including the scavenging air cooler 14. The seawater pumped by the seawater pump is supplied to, for example, the condenser 3 of the freshwater generator 1 as steam cooling water.

[0029] A second raw water supply line L5 is connected to the scavenging air cooling water supply line L2 using, for example, a pipe joint. The second raw water supply line L5 is a pipe through which scavenging air cooling water flows in order to supply at least a part of the scavenging air cooling water used for cooling the scavenging air to the heater 2 of the fresh water generator 1. At least a part of the scavenging air cooling water whose temperature has increased as the scavenging air is cooled in the scavenging air cooler 14 is used as raw water for producing fresh water in the heater 2 of the fresh water generator 1, and the remainder is supplied to a location in the ship where seawater is used.

[0030] The flow rate of scavenging air-cooling water supplied from the scavenging air-cooling water supply line L2 through the second raw water supply line L5 to the heater 2 of the fresh water generator 1 is adjusted by a flow control valve 5. The opening / closing and opening degree of the flow control valve 5 are preferably controlled by a control device. The flow rate of scavenging air-cooling water supplied as raw water to the heater 2 of the fresh water generator 1 through the second raw water supply line L5 is preferably adjusted by the control device based on the seawater temperature detected by a temperature sensor 6 described later. The flow control valve 5 may be provided with a flow meter, and the detection result by the flow meter may be monitored by the control device.

[0031] The freshwater generator 1 includes a heater 2 and a condenser 3. In the freshwater generator 1, seawater is supplied to the heater 2 as raw water, and the raw water is heated and evaporated in the heater 2. After that, the raw water is separated into gas and liquid, and the steam resulting from the gas-liquid separation is condensed in the condenser 3 to produce freshwater. The interior of the freshwater generator 1 is maintained under reduced pressure or in a vacuum state by a pressure reducing means such as a water ejector. The freshwater generator 1 is not particularly limited as long as it desalinates seawater. Examples of the freshwater generator 1 include multi-tube freshwater generators (e.g., those disclosed in JP 2022-51869 A, JP 2019-195750 A, and JP 2016-205242 A), but may also be a plate-type or other type freshwater generator. The freshwater generator 1 may be a single-effect freshwater generator, or may be a double- or higher-effect multiple-effect freshwater generator.

[0032] In the freshwater generator 1, the heater 2 heats raw water to generate steam. The heater 2 is not particularly limited, and may include, for example, a tubular heat exchanger. Seawater (scavenging air cooling water or steam cooling water) is supplied as raw water to the heater 2 through a raw water supply line L4 or a second raw water supply line L5. A heating fluid for heating the raw water, preferably jacket cooling water used to cool the diesel engine 10, is supplied to the heater 2 through a heating fluid supply line L3. In the heater 2, the seawater supplied as raw water is heated by heat exchange with the jacket cooling water, and after its temperature rises, it evaporates. The steam generated by the evaporation of the raw water is supplied to the condenser 3.

[0033] The temperature of the jacket cooling water after cooling the diesel engine 10 is high, at approximately 80°C to 90°C. On the other hand, the evaporation temperature of seawater in the heater 2 of the freshwater generator 1 under reduced pressure is generally approximately 55°C to 60°C. Therefore, in the freshwater generator 1 under reduced pressure, raw water can be heated by the jacket cooling water to effectively evaporate the raw water and generate steam. Therefore, by using the jacket cooling water as the main heat source for evaporating the raw water in the freshwater generator 1, a sufficient amount of fresh water can be obtained.

[0034] In the freshwater generator 1, the condenser 3 cools and condenses the steam generated by evaporation of the raw water. The condenser 3 is not particularly limited, but may include, for example, a tubular heat exchanger. Seawater pumped from the sea and brought into the ship is supplied to the condenser 3 via a steam cooling water supply line L6 as steam cooling water for cooling the steam. When the steam cooling water is supplied to the condenser 3, the steam is cooled in the condenser 3 by heat exchange with the steam cooling water, and condenses after its temperature has dropped. The fresh water produced by condensing the steam is discharged outside the freshwater generator 1 and supplied to a water storage tank via a fresh water supply line L7.

[0035] At least a portion of the steam cooling water, the temperature of which has increased as a result of cooling the steam in the condenser 3, is supplied to the heater 2 of the fresh water generator 1 and used as raw water for producing fresh water in the heater 2, with the remainder being discharged outside the system, such as outside the ship. The raw water supply line L4 is a pipe through which the steam cooling water flows in order to supply at least a portion of the steam cooling water used to cool the steam to the heater 2 of the fresh water generator 1.

[0036] The flow rate of the steam cooling water supplied from the condenser 3 to the heater 2 of the freshwater generator 1 through the raw water supply line L4 is adjusted by a flow control valve 4. The opening / closing and opening degree of the flow control valve 4 are preferably controlled by a control device. The flow rate of the steam cooling water supplied as raw water to the heater 2 of the freshwater generator 1 through the raw water supply line L4 is preferably adjusted by the control device based on the seawater temperature detected by a temperature sensor 6. The flow control valve 4 may be equipped with a flow meter, and the detection results from the flow meter may be monitored by the control device.

[0037] The temperature sensor 6 is connected to the steam cooling water supply line L6. The temperature sensor 6 measures the temperature of seawater supplied as steam cooling water to the condenser 3 of the freshwater generator 1. A conventionally known temperature sensor can be used as the temperature sensor 6. The detection result by the temperature sensor 6 is preferably monitored by a control device.

[0038] The control device may be configured as a general-purpose computer or as a dedicated computer such as a control panel.

[0039] Next, a description will be given of a seawater desalination method in the fresh water production system 100 of this embodiment. In order to convert steam generated in the heater 2 of the fresh water production apparatus 1 into fresh water in the condenser 3, steam cooling water is supplied to the condenser 3 through a steam cooling water supply line L6.

[0040] The steam cooling water supplied to the condenser 3 is, for example, seawater pumped from the ocean, but the temperature of the seawater varies depending on the season and region. Here, part of the steam cooling water supplied to the condenser 3 cools the steam and is then supplied to the heater 2 as raw water. If the seawater temperature is lower than a predetermined temperature, the temperature of the raw water supplied to the heater 2 will be low. If the temperature of the raw water is low, the temperature of the raw water will be too low compared to the amount of heat supplied to the heater 2 for evaporation of the raw water, and the raw water will not evaporate efficiently, which may result in a decrease in the freshwater production performance of the freshwater generator 1.

[0041] Therefore, in the fresh water production system 100 of this embodiment, it is determined whether the temperature of seawater supplied as steam cooling water to the condenser 3 of the fresh water production apparatus 1 is lower than a predetermined temperature based on the temperature measured by the temperature sensor 6. The predetermined temperature is set based on the estimated temperature of the steam cooling water after cooling the steam in the condenser 3, and the seawater temperature at which the estimated temperature of the steam cooling water after cooling the steam is expected to be higher than the temperature of the scavenging air cooling water after cooling the scavenging air is set as the predetermined temperature.

[0042] When the seawater temperature measured by the temperature sensor 6 is lower than a predetermined temperature, seawater having a higher temperature than the steam cooling water used to cool the steam in the condenser 3 needs to be supplied as raw water to the heater 2. Therefore, for example, by controlling the control device to close the flow control valve 4 of the raw water supply line L4 and open the flow control valve 5 of the second raw water supply line L5, at least a part of the scavenging air cooling water used to cool the scavenging air in the scavenging air cooler 14 is supplied as raw water to the heater 2.

[0043] When seawater is used as the scavenging air cooling water, the temperature after cooling the scavenging air is generally about 45°C to 50°C. The evaporation temperature of seawater, which serves as raw water in the heater 2 of the fresh water generator 1, is generally about 55°C to 60°C. Therefore, when the seawater temperature measured by the temperature sensor 6 is lower than a predetermined temperature, the scavenging air cooling water used to cool the scavenging air in the scavenging air cooler 14 is supplied as raw water to the heater 2 of the fresh water generator 1 instead of the steam cooling water used to cool the steam in the condenser 3. This reduces the amount of sensible heat required to raise the temperature of the raw water in the heater 2 until it evaporates, and increases the amount of latent heat required to evaporate the raw water, which contributes to the actual amount of fresh water produced. This improves the thermal efficiency of the heater 2 and prevents a decrease in the fresh water production performance of the fresh water generator 1, such as an increase in the amount of fresh water produced.

[0044] On the other hand, when the seawater temperature measured by the temperature sensor 6 is equal to or higher than a predetermined temperature, for example, by controlling the control device to open the flow control valve 4 of the raw water supply line L4 and close the flow control valve 5 of the second raw water supply line L5, the steam cooling water used to cool the steam in the condenser 3 can be supplied as raw water to the heater 2 of the fresh water generator 1. In this case, the temperature of the steam cooling water after cooling the steam is higher than the temperature of the scavenging air cooling water after cooling the scavenging air, so the fresh water production performance of the fresh water generator 1 does not decrease due to the raw water temperature being too low.

[0045] The raw water supplied to the heater 2 of the fresh water generator 1 is heated in the heater 2 by the jacket cooling water, which has become hot due to cooling of the diesel engine 10, and the raw water is evaporated. The steam thus generated is cooled and condensed in the condenser 3 to produce fresh water. The fresh water produced in the fresh water generator 1 is discharged outside the apparatus through a fresh water supply line L7.

[0046] In the fresh water production system 100 of the above-described embodiment, the temperature of seawater supplied as steam cooling water to the condenser 3 of the fresh water production system 1 is measured by the temperature sensor 6 in the steam cooling water supply line L6, and when the seawater temperature measured by the temperature sensor 6 is lower than a predetermined temperature, at least a part of the scavenging air cooling water, the temperature of which has increased as a result of cooling the scavenging air in the scavenging air cooler 14, is supplied as raw water to the heater 2 of the fresh water production system 1. In this way, when the temperature of seawater used for steam cooling water is low, the scavenging air cooling water used for cooling the scavenging air is supplied to the heater 2, whereby high-temperature raw water can be supplied to the heater 2, and the raw water can be efficiently evaporated in the heater 2. Therefore, according to the fresh water production system 100 of the embodiment, the waste heat of the scavenging air cooling water can be effectively used to improve the fresh water production performance of the fresh water production system 1.

[0047] Furthermore, in the fresh water production system 100 of the above-described embodiment, when the seawater temperature measured by the temperature sensor 6 is higher than a predetermined temperature, at least a part of the steam cooling water, the temperature of which has increased as the steam is cooled in the condenser 3 of the fresh water production system 1, is supplied as raw water to the heater 2 of the fresh water production system 1. In this way, when the temperature of seawater used for steam cooling water is high, the steam cooling water used for cooling the steam is supplied to the heater 2, thereby making it possible to supply high-temperature raw water to the heater 2 and efficiently evaporate the raw water in the heater 2. Therefore, according to the fresh water production system 100 of the above-described embodiment, high-temperature raw water can be stably supplied to the heater 2 regardless of the seawater temperature by simple control such as monitoring the seawater temperature and supplying either scavenging air cooling water or steam cooling water to the heater 2 as raw water, thereby suppressing a decrease in fresh water production performance even if the seawater temperature fluctuates.

[0048] Furthermore, in the fresh water production system 100 of the above-described embodiment, at least a portion of the jacket cooling water, which has become hot as a result of cooling the diesel engine 10, is supplied as a heating fluid to the heater 2 of the fresh water production system 1, and the raw water is evaporated by heat exchange between the jacket cooling water and the raw water in the heater 2. Therefore, in the fresh water production system 100 of the above-described embodiment, the waste heat of the jacket cooling water can be effectively used for desalination of seawater in the fresh water production system 1.

[0049] While one embodiment of the fresh water production system of the present invention has been described above, the embodiment shown in Fig. 1 above is merely an example and is not limiting. Therefore, the fresh water production system of the present invention is not limited to the embodiment shown in Fig. 1 above, and various modifications are possible without departing from the spirit of the present invention.

[0050] <Variation 1> 1 described above, when the seawater temperature measured by the temperature sensor 6 is lower than a predetermined temperature, the scavenging air cooling water used to cool the scavenging air in the scavenging air cooler 14 is supplied as raw water to the heater 2 instead of the steam cooling water used to cool the steam in the condenser 3. As another embodiment, as shown in FIG. 2, when the seawater temperature measured by the temperature sensor 6 is lower than a predetermined temperature, at least a part of the scavenging air cooling water used to cool the scavenging air in the scavenging air cooler 14 may be mixed with the steam cooling water used to cool the steam in the condenser 3, and the mixture may be supplied to the heater 2 as raw water together with the steam cooling water.

[0051] 2, the downstream end of the second raw water supply line L5 is preferably connected to the raw water supply line L4 using, for example, a pipe joint, etc. By mixing the high-temperature scavenging air cooling water flowing through the second raw water supply line L5 with the low-temperature steam cooling water flowing through the raw water supply line L4, the temperature of the raw water supplied to the heater 2 of the fresh water generator 1 can be adjusted to an appropriate temperature.

[0052] 2, for example, a control device adjusts the openings of the flow rate control valves 4 and 5 based on the seawater temperature measured by the temperature sensor 6, thereby making it possible to mix scavenging air cooling water from the second raw water supply line L5 with the steam cooling water flowing through the raw water supply line L4 at a flow rate necessary to raise the temperature to an appropriate level for use as raw water for the heater 2. In the embodiment shown in Fig. 2, a temperature sensor 7 may be provided in the raw water supply line L4 at a position downstream of the position where the second raw water supply line L5 is connected, and the detection result by the temperature sensor 7 may be monitored by the control device.

[0053] <Variation 2> 1 and 2, when the seawater temperature measured by the temperature sensor 6 is lower than a predetermined temperature, the scavenging air cooling water used for cooling the scavenging air in the scavenging air cooler 14 is directly supplied as raw water to the heater 2 of the fresh water generator 1. As another embodiment, as shown in Fig. 3, when the seawater temperature measured by the temperature sensor 6 is lower than a predetermined temperature, at least a part of the scavenging air cooling water used for cooling the scavenging air in the scavenging air cooler 14 may be mixed with seawater supplied as steam cooling water to the condenser 3 of the fresh water generator 1. In the embodiment shown in Fig. 3, a scavenging air cooling water make-up line L8 branches off from the scavenging air cooling water supply line L2 using a pipe joint or the like and is connected to the steam cooling water supply line L6.

[0054] The flow rate of scavenging air cooling water that flows from the scavenging air cooling water supply line L2 through the scavenging air cooling water make-up line L8 and is mixed into the steam cooling water supply line L6 is adjusted by a flow control valve 8. The opening / closing and opening degree of the flow control valve 8 are preferably controlled by a control device. The flow rate of scavenging air cooling water that is mixed into the steam cooling water supply line L6 through the scavenging air cooling water make-up line L8 is preferably adjusted by the control device based on the seawater temperature detected by a temperature sensor 6, which will be described later. The flow control valve 8 may be provided with a flow meter, and the detection result by the flow meter may be monitored by the control device.

[0055] The seawater supplied to the condenser 3 of the freshwater generator 1 as steam cooling water is, for example, seawater pumped from the ocean, but the temperature of the seawater varies depending on the season and region. If the flow rate of seawater supplied to the condenser 3 of the freshwater generator 1 as steam cooling water is high when the seawater temperature is low, the evaporation temperature in the freshwater generator 1 decreases, which results in an increase in the salinity of the freshwater produced by the freshwater generator 1, and this may reduce the freshwater production performance of the freshwater generator 1. Furthermore, some of the seawater supplied to the condenser 3 as steam cooling water is supplied to the heater 2 as raw water after cooling the steam. If the seawater temperature is low, the temperature of the raw water supplied to the heater 2 will be low. If the temperature of the raw water is low, the temperature of the raw water will be too low compared to the amount of heat supplied to the heater 2 for evaporation of the raw water, and the raw water will not evaporate efficiently, which may reduce the freshwater production performance of the freshwater generator 1.

[0056] 3, the fresh water production system 100 determines whether the temperature of seawater supplied as steam cooling water to the condenser 3 of the fresh water production system 1 in the steam cooling water supply line L6 is lower than a predetermined temperature based on the temperature measured by the temperature sensor 6. The predetermined temperature is, for example, 10°C.

[0057] When the seawater temperature measured by the temperature sensor 6 is lower than a predetermined temperature, it is necessary to increase the temperature of the seawater supplied as steam cooling water to the condenser 3 of the fresh water generator 1. Therefore, for example, by a control device adjusting the aperture of the flow rate control valve 8 based on the seawater temperature measured by the temperature sensor 6, scavenging air cooling water can be mixed from the scavenging air cooling water supply line L8 at a flow rate necessary to raise the temperature of the seawater supplied as steam cooling water to an appropriate temperature for steam cooling water. In the embodiment shown in Fig. 3 , a temperature sensor 9 may be provided in the steam cooling water supply line L6 at a position downstream of the position where the scavenging air cooling water supply line L8 is connected, and the detection result by the temperature sensor 9 may be monitored by the control device.

[0058] In the embodiment shown in FIG. 3, the temperature of the steam cooling water supplied to the condenser 3 of the fresh water generator 1 can be adjusted to an appropriate temperature by mixing low-temperature seawater with high-temperature scavenging air cooling water flowing through the scavenging air cooling water supply line L8.

[0059] Furthermore, by adjusting the temperature of the steam cooling water supplied to the condenser 3 of the fresh water generator 1 to an appropriate temperature, the temperature of the steam cooling water after cooling the steam becomes high. Therefore, even if the steam cooling water used to cool the steam in the condenser 3 is subsequently supplied to the heater 2 of the fresh water generator 1 as raw water, the temperature of the raw water will not be too low.

[0060] As described above, in the fresh water production system 100 of the embodiment shown in FIG. 3 , the temperature of seawater supplied as steam cooling water to the condenser 3 of the fresh water production system 1 is measured by the temperature sensor 6 through the steam cooling water supply line L6. When the seawater temperature measured by the temperature sensor 6 is lower than a predetermined temperature, at least a portion of the scavenging air cooling water, the temperature of which has increased as a result of cooling the scavenging air in the scavenging air cooler 14, is mixed with the seawater supplied as steam cooling water to the condenser 3. In this way, by supplementing the seawater with the scavenging air cooling water used to cool the scavenging air when the seawater temperature is low, steam cooling water at an appropriate temperature can be stably supplied to the condenser 3, thereby improving the fresh water production performance of the fresh water production system 1. Furthermore, high-temperature raw water can be stably supplied to the heater 2 of the fresh water production system 1, thereby improving the fresh water production performance of the fresh water production system 1. Therefore, the fresh water production system 100 of the embodiment can effectively utilize the waste heat of the scavenging air cooling water to improve the fresh water production performance of the fresh water production system 1.

[0061] <Variation 3> 1 to 3, the fresh water generator 1 may include a preheater equipped with, for example, a tubular heat exchanger. Specifically, a portion of the steam cooling water used for condensing steam in the condenser 3 of the fresh water generator 1 may be supplied to the preheater to preheat the steam cooling water by heat exchange with the steam, and a portion of the preheated steam cooling water may be supplied to the heater 2 as raw water.

[0062] <Variation 4> In the above-described embodiment of FIGS. 1 to 3, the heating fluid for evaporating the raw water in the heater 2 of the fresh water generator 1 does not necessarily have to be jacket cooling water, but may be steam from a boiler. [Explanation of symbols]

[0063] 1 Water generator 2 Heater 3 Condenser 4. Flow control valve 5. Flow control valve 6 Temperature Sensor 8 Flow control valve 10 Diesel engine (internal combustion engine) 14 Scavenging air cooler L2 Scavenging air cooling water supply line L4 Raw water supply line L5 Second raw water supply line L6 Steam cooling water supply line L8 Scavenging air cooling water supply line

Claims

1. A water production system for desalination of seawater on a ship, comprising: a freshwater generator including a heater to which seawater is supplied as raw water and which heats and evaporates the raw water, and a condenser to which seawater is supplied as steam cooling water and which cools and condenses steam generated by evaporation of the raw water using the steam cooling water; a steam cooling water supply line for supplying steam cooling water to the condenser; a raw water supply line for supplying at least a portion of the steam cooling water used to cool the steam in the condenser to the heater; a temperature sensor for measuring the temperature of seawater supplied to the condenser as steam cooling water; a scavenging air cooling water supply line for supplying seawater to a scavenging air cooler as scavenging air cooling water for cooling scavenging air supplied to the marine internal combustion engine; Equipped with a fresh water production system configured to mix at least a part of scavenging air cooling water used for cooling the scavenging air in the scavenging air cooler with seawater supplied to the condenser as steam cooling water from the scavenging air cooling water supply line, or to supply the seawater as raw water to the heater, when the seawater temperature measured by the temperature sensor is lower than a predetermined temperature.

2. a second raw water supply line connected to the scavenging air cooling water supply line, for supplying at least a portion of the scavenging air cooling water used to cool the scavenging air to the heater or for mixing the scavenging air cooling water with the raw water supply line; a first flow rate regulating valve that regulates the flow rate of the steam cooling water flowing through the raw water supply line; a second flow rate control valve that adjusts the flow rate of scavenging air cooling water flowing through the second raw water supply line; 2. The freshwater production system according to claim 1, further comprising: a control device that controls the first flow rate adjustment valve and the second flow rate adjustment valve based on the seawater temperature measured by the temperature sensor.

3. the second raw water supply line supplies at least a portion of the scavenging air cooling water used to cool the scavenging air to the heater; 3. The freshwater production system according to claim 2, wherein the control device controls the first flow control valve and the second flow control valve so as to close the first flow control valve and open the second flow control valve when the seawater temperature measured by the temperature sensor is lower than a predetermined temperature, and to open the first flow control valve and close the second flow control valve when the seawater temperature measured by the temperature sensor is higher than the predetermined temperature.

4. a scavenging air cooling water supply line connected to the scavenging air cooling water supply line for mixing at least a portion of the scavenging air cooling water used to cool the scavenging air with seawater to be supplied to the condenser as steam cooling water; a flow rate regulating valve for regulating the flow rate of the scavenging air cooling water flowing through the scavenging air cooling water supply line; The fresh water production system according to claim 1 , further comprising: a control device that controls the flow rate adjustment valve based on the seawater temperature measured by the temperature sensor.

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