Water production system

Abstract

To provide a water production system capable of effectively using the waste heat of scavenging-air cooling water.SOLUTION: There is provided a water production system 1 desalinating seawater introduced into a ship. The water production system 1 comprises: a water production device 2 comprising a heater 3 heating and vaporizing seawater and a condenser 4 cooling and condensing steam generated by the vaporization of seawater; a scavenging-air cooler 14 configured to exchange heat with scavenging-air cooling water to cool scavenging-air fed to an internal combustion engine (diesel engine 10) for a ship; and a feedwater heater 5 configured to exchange heat at least with a part of the scavenging-air cooling water discharged from the scavenging-air cooler 14 to heat seawater being fed to the heater 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a freshwater production system for desalinating 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 by evaporating seawater pumped from the sea under reduced pressure such as under vacuum using waste heat from an internal combustion engine such as a diesel engine mounted on the ship as a heat source. For example, in the fresh water generator described in Patent Document 1, scavenging air cooling water used for cooling scavenging air supplied to a diesel engine is introduced to the fresh water generator, and the waste heat of the scavenging air cooling water is used to evaporate seawater in the fresh water generator. In the fresh water generator, seawater is evaporated by heat exchange with the scavenging air cooling water, and the generated steam is cooled and condensed 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 about 60°C when the scavenging air cooling water is fresh water, and is generally lower when the scavenging air cooling water is seawater than when it is fresh water. In the fresh water generator, seawater is evaporated under reduced pressure, but it is difficult to efficiently evaporate seawater with scavenging air cooling water at about 60°C. Therefore, if the waste heat of the scavenging air cooling water is used as the main heat source for producing fresh water in the fresh water generator, there is a problem that the performance of the fresh water generator is reduced because there is not enough heat to obtain a sufficient amount of fresh water (fresh water). Alternatively, if a large heat transfer area is secured for heat exchange between seawater and scavenging air cooling water in order to obtain a sufficient amount of fresh water (fresh water), there is a problem that the fresh water generator becomes large.

[0005] The present invention has been made with a focus on solving the above problems, and has an object to provide a water production system that can effectively utilize the waste heat of scavenging air cooling water. [Means for solving the problem]

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

[0007] Item 1. A water production system that desalinates seawater taken into a ship, a freshwater generating system including a heater for heating and evaporating seawater, and a condenser for cooling and condensing steam generated by the evaporation of the seawater; A scavenging air cooler configured to cool scavenging air supplied to the marine internal combustion engine by heat exchange with scavenging air cooling water; a feed water heater configured to heat seawater supplied to the heater by heat exchange with at least a portion of the scavenging air cooling water discharged from the scavenging air cooler; A water production system comprising:

[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. The condenser is configured to cool the steam generated by evaporation of seawater by heat exchange with the seawater taken into the ship, Item 2. The water production system according to item 1, wherein the seawater after heat exchange with the steam in the condenser is heated in the feedwater heater.

[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 items 1 and 2 above.

[0011] Item 3. The water production system according to claim 1 or 2, wherein the scavenging air cooling water is fresh water.

[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 items 1 to 3 above.

[0013] Item 4. The water production system according to any one of Items 1 to 3, wherein the heater is configured to heat seawater by heat exchange with jacket cooling water used to cool the internal combustion engine. Effect of the Invention

[0014] According to the fresh water production system of the present invention, the waste heat of the scavenging air cooling water can be effectively utilized to improve the performance of the fresh water production device. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic configuration diagram of a fresh water production system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The freshwater production system of the present invention improves the performance of the freshwater production system by utilizing waste heat from an internal combustion engine, which is the main engine that generates the propulsive force in a ship, for desalinating seawater in the freshwater production system. The internal combustion engine is, for example, a diesel engine.

[0017] 1 is a schematic diagram of a fresh water production system 1 according to one embodiment of the present invention. The fresh water production system 1 includes at least a fresh water production device 2 including a heater 3 and a condenser 4, a scavenging air cooler 14 for cooling scavenging air supplied to a diesel engine 10, and a feed water heater 5.

[0018] 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. In the diesel engine 10, cooling water (jacket cooling water) for cooling the diesel engine 10 is circulated through a first circulation passage 15.

[0019] The first circulation flow path 15 is a pipe that supplies jacket cooling water to the diesel engine 10, and the jacket cooling water circulates through the first circulation flow path 15 by driving a pump 19. A flow rate control valve 20 and a cooler 21 are connected to the first circulation flow path 15. The flow rate control valve 20 adjusts the flow rate of the jacket cooling water supplied to the diesel engine 10. The flow rate control valve 20 may be equipped with a flow meter. The cooler 21 cools the jacket cooling water discharged from the diesel engine 10 and heated to a high temperature. The cooler 21 is, for example, a heat exchanger, and is supplied with cooling water from a central cooler. In the cooler 21, the jacket cooling water is cooled by heat exchange with the cooling water.

[0020] The turbocharger 11 supplies scavenging air to the diesel engine 10. The turbocharger 11 includes a turbine 12 driven by exhaust gas discharged by the diesel engine 10 combusting a main fuel, and a compressor 13 that compresses outside air by the rotational power of the turbine 12. The turbocharger 11 supplies the compressed outside air to the diesel engine 10 as scavenging air.

[0021] 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 for the purpose of increasing the air density (weight per unit volume) and is then supplied to the diesel engine 10. The scavenging air cooler 14 is, for example, a heat exchanger, and cooling water (scavenging air cooling water) for cooling the scavenging air is circulated through a second circulation passage 17. Fresh water or seawater is used as the scavenging air cooling water.

[0022] The second circulation passage 17 is a pipe for supplying scavenging air cooling water to the scavenging air cooler 14, and the scavenging air cooling water circulates through the second circulation passage 17 by driving a circulation pump 22. A flow rate control valve 23 and a cooler 24 are connected to the second circulation passage 17. The flow rate control valve 23 adjusts the flow rate of the scavenging air cooling water supplied to the scavenging air cooler 14. The flow rate control valve 23 may be provided with a flow meter. The cooler 24 cools the scavenging air cooling water that has become hot by cooling the scavenging air in the scavenging air cooler 14. The cooler 24 is, for example, a heat exchanger, and cooling water is supplied from a central cooler. In the cooler 24, the scavenging air cooling water is cooled by heat exchange with the cooling water.

[0023] The freshwater generator 2 generates fresh water by heating seawater to generate steam, separating the steam into gas and liquid, and condensing the steam after the gas-liquid separation. The inside of the freshwater generator 2 is maintained in a reduced pressure (vacuum) state by a pressure reducing means such as a water ejector. The freshwater generator 2 is not particularly limited as long as it desalinates seawater. Examples of the freshwater generator 2 include a flash type freshwater generator (e.g., JP 2009-90228 A), a plate type freshwater generator (e.g., JP 9-299927 A), a multi-tube type freshwater generator (e.g., JP 2013-166141 A), and a membrane distillation type freshwater generator (e.g., JP 6-7644 A). The freshwater generator 2 may be a single-effect evaporative concentration apparatus, or a double-effect or more multiple-effect evaporative concentration apparatus.

[0024] In the freshwater generator 2, the heater 3 heats and evaporates seawater introduced into the freshwater generator 2. Seawater, which is a raw material for freshwater, is supplied to the heater 3 through a seawater supply passage 6. The heater 3 is equipped with, but is not limited to, a tubular heat exchanger, for example. The heater 3 is supplied with, but is not limited to, jacket cooling water used to cool a diesel engine 10, for example, as a heat source for evaporating seawater. In the heater 3, the supplied seawater is heated by heat exchange with the jacket cooling water, and is evaporated after its temperature has increased. Steam generated by the evaporation of the seawater is supplied to the condenser 4.

[0025] The temperature of the jacket cooling water after cooling the diesel engine 10 is about 80°C to 90°C. Therefore, seawater can be effectively evaporated by heating it with the jacket cooling water under reduced pressure. Therefore, by using the jacket cooling water as the main heat source for producing fresh water in the fresh water generator 2, a sufficient amount of fresh water (clean water) can be obtained.

[0026] The jacket cooling water after cooling the diesel engine 10 circulates through the heater 3 via a first bypass flow path 16. The first bypass flow path 16 is a pipe that guides the jacket cooling water that has become hot by cooling the diesel engine 10 to the heater 3. A part of the jacket cooling water is diverted from the first circulation flow path 15 via the first bypass flow path 16, passes through the heater 3, and then returns to the first circulation flow path 15.

[0027] A temperature sensor 25 and a flow rate control valve 26 are connected to the first bypass flow path 16. The flow rate control valve 26 adjusts the flow rate of jacket cooling water (jacket cooling water supplied to the heater 3) diverted from the first circulation flow path 15 to the first bypass flow path 16. The flow rate control valve 26 may be equipped with a flow meter. The temperature sensor 25 measures the temperature of the jacket cooling water supplied to the heater 3. Based on the temperature of the jacket cooling water detected by the temperature sensor 25, the flow rate of the jacket cooling water supplied to the heater 3 is adjusted.

[0028] In the freshwater generator 2, the condenser 4 cools and condenses the steam generated by evaporation of seawater. The condenser 4 is equipped with, but is not limited to, a tubular heat exchanger, for example. The condenser 4 is supplied with, but is not limited to, seawater pumped from the sea and taken into the ship through a seawater inlet passage 7 as a heat source for condensing the steam. When the seawater pumped from the sea is introduced into the freshwater generator 2, the seawater is supplied to the condenser 4. In the condenser 4, the steam generated by evaporation of the seawater is cooled by heat exchange with the seawater, and condenses after its temperature has decreased. The fresh water (distilled water) generated by condensation of the steam is discharged outside the freshwater generator 2 by a pump and then stored in a water storage tank.

[0029] After the seawater has exchanged heat with the steam in the condenser 4, a part of the seawater is discharged outside the system, such as outside the ship, and a part of the seawater is supplied to the heater 3 through a seawater supply passage 6 as raw seawater.

[0030] The feedwater heater 5 is provided in the seawater supply passage 6 and heats the seawater supplied from the condenser 4 to the heater 3. By raising the temperature of seawater, which is the raw material for fresh water, and supplying it to the heater 3, it is possible to reduce the amount of heat (sensible heat) required to raise the temperature of the seawater in the heater 3 until it evaporates, and to increase the amount of heat (latent heat) required to evaporate the seawater, which contributes to the actual amount of fresh water produced. This makes it possible to improve the thermal efficiency of the heater 3, improve the performance of the fresh water producer 2, such as increasing the amount of fresh water produced, and also make it possible to reduce the size of the fresh water producer 2.

[0031] The feedwater heater 5 is, for example, a tubular heat exchanger, but is not particularly limited thereto. Scavenging air cooling water used for cooling the scavenging air is supplied to the feedwater heater 5 as a heat source for increasing the temperature of the seawater. In the feedwater heater 5, the supplied seawater is heated by heat exchange with the scavenging air cooling water, and the temperature of the seawater increases. The seawater with the increased temperature is supplied to the heater 3 as raw seawater.

[0032] When the scavenging air cooling water is fresh water, the temperature after cooling the scavenging air is about 60°C. On the other hand, when the scavenging air cooling water is seawater, the temperature after cooling the scavenging air is generally about 45°C to 50°C. When the scavenging air cooling water is seawater, if the temperature after cooling the scavenging air becomes too high, there is a risk of significant scale generation. If a large amount of scale adheres to the heat exchanger through which the scavenging air cooling water flows, it leads to a decrease in the performance of the heat exchanger. Therefore, when the scavenging air cooling water is seawater, the temperature after cooling the scavenging air is limited to about 45°C to 50°C. Therefore, in order to raise the temperature of seawater, which is the raw material for fresh water, as much as possible by the feed water heater 5 and supply it to the heater 3, it is preferable that the scavenging air cooling water is fresh water.

[0033] The scavenging air cooling water after cooling the scavenging air is circulated through the feed water heater 5 by the second bypass passage 18. The second bypass passage 18 is a pipe that guides the scavenging air cooling water that has become hot by cooling the scavenging air to the feed water heater 5. At least a part of the scavenging air cooling water is diverted from the second circulation passage 17 via the second bypass passage 18, passes through the feed water heater 5, and then returns to the second circulation passage 17.

[0034] A temperature sensor 27 and a flow rate control valve 28 are connected to the second circulation passage 17. The flow rate control valve 28 adjusts the flow rate of scavenging air cooling water (scavenging air cooling water supplied to the feed water heater 5) diverted from the second circulation passage 17 to the second bypass passage 18. The flow rate control valve 28 may be equipped with a flow meter. The temperature sensor 27 measures the temperature of the scavenging air cooling water supplied to the feed water heater 5. Based on the temperature of the scavenging air cooling water detected by the temperature sensor 27, the flow rate of the scavenging air cooling water supplied to the feed water heater 5 is adjusted.

[0035] According to the freshwater production system 1 of the above-mentioned embodiment, at least a part of the scavenging air cooling water used for cooling the scavenging air supplied to the diesel engine 10 is supplied to the feedwater heater 5, and the temperature of the raw seawater is increased in the feedwater heater 5 by heat exchange between the scavenging air cooling water and the raw seawater supplied to the heater 3 of the freshwater production system 2. As a result, raw seawater of a higher temperature is supplied to the heater 3 of the freshwater production system 2, and the raw seawater can be efficiently heated and evaporated in the heater 3, thereby improving the performance of the freshwater production system 2.

[0036] In this manner, in the freshwater production system 1 of the above-described embodiment, the performance of the freshwater production apparatus 2 is improved by recovering the waste heat of the scavenging air cooling water in the raw seawater, and the waste heat of the scavenging air cooling water can be effectively utilized.

[0037] Furthermore, according to the freshwater production system 1 of the above-described embodiment, at least a part of the jacket cooling water used for cooling the diesel engine 10 is supplied to the heater 3 of the freshwater production apparatus 2, and the raw seawater is evaporated by heat exchange between the jacket cooling water and the raw seawater in the heater 3. Therefore, the freshwater production system 1 of the above-described embodiment can effectively utilize the waste heat of the jacket cooling water.

[0038] Although one embodiment of the freshwater production system of the present invention has been described above, the above-mentioned embodiment is merely illustrative and not restrictive. Therefore, the freshwater production system of the present invention is not limited to the above-mentioned embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0039] For example, in the above-described embodiment, the feed water heater 5 is provided outside the fresh water generator 2, but it may be provided inside the fresh water generator 2.

[0040] For example, in the above-described embodiment, the freshwater generator 2 may include a preheater equipped with, for example, a tubular heat exchanger. Specifically, a part of the seawater used for condensing the steam in the condenser 4 of the freshwater generator 2 may be supplied to the preheater to preheat the seawater by heat exchange with the steam, and the preheated seawater may be supplied to the feedwater heater 5 and then supplied to the heater 3 as raw seawater.

[0041] For example, in the above-described embodiment, the main heat source for evaporation of seawater in the heater 3 of the freshwater generator 2 does not necessarily have to be the waste heat of the jacket cooling water, and may be steam from a boiler. [Explanation of symbols]

[0042] 1. Water production system 2 Water generator 3 Heater 4 Condenser 5 Feed water heater 10 Diesel engine (internal combustion engine) 14 Scavenging air cooler

Claims

1. A water production system for desalinating seawater taken into a ship, comprising: a freshwater generating system including a heater for heating and evaporating seawater, and a condenser for cooling and condensing steam generated by the evaporation of the seawater; A scavenging air cooler configured to cool scavenging air supplied to the marine internal combustion engine by heat exchange with scavenging air cooling water; a feed water heater configured to heat seawater supplied to the heater by heat exchange with at least a portion of the scavenging air cooling water discharged from the scavenging air cooler; A water production system comprising:

2. The condenser is configured to cool steam generated by evaporation of seawater by heat exchange with seawater taken into the ship, The water production system according to claim 1 , wherein the seawater after heat exchange with the steam in the condenser is heated in the feedwater heater.

3. The water production system according to claim 1 , wherein the scavenging air cooling water is fresh water.

4. 2. The freshwater production system according to claim 1, wherein the heater is configured to heat the seawater by heat exchange with jacket cooling water used to cool the internal combustion engine.

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