JP2015202445A - Reduced-pressure boiling-type seawater desalination apparatus with power generating function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy-efficient seawater desalination apparatus effective in reducing running costs.SOLUTION: A reduced-pressure boiling-type seawater desalination apparatus includes a seawater tower 11 to be erected in seawater, a freshwater tower 12 to be erected in freshwater, a communication pipe 13 for communicating with the towers, means 19 for heating seawater, cooling means 14, and an open-type radial turbine generator using steam as working fluid. The upper space of the seawater tower 11 and the upper space of the freshwater tower 12 are maintained in vacuum. Using Torricelli vacuum, the seawater is boiled at a temperature close to room temperature, and the steam generated is used to drive the turbine for power generation. After power generation, the steam is cooled and condensed to obtain freshwater. The seawater and the freshwater are autonomously transported due to the difference in gravity. Different from conventional reduced-pressure distillation apparatuses, the desalination apparatus can thereby have a nearly zero operation cost.

Description

The present invention relates to a seawater desalination method using a vacuum and a vacuum distillation method that desalinates seawater with energy saving, and more specifically, a small radial turbine is driven by water vapor generated by vacuum distillation to generate electric power. The present invention relates to an energy-saving seawater desalination method and a seawater desalination apparatus that use this electric power as heating energy necessary for distillation of seawater.

In recent years, there has been a worldwide shortage of water (fresh water), and one solution is seawater desalination. Various methods such as distillation, reverse osmosis, electrodialysis, and freezing methods have been proposed for desalination of seawater. Currently, about 60% are evaporation methods and about 30% are reverse osmosis methods. It has been realized. However, in reality, there are various problems such as high construction cost and high operation cost of each device, a new seawater desalination device that can save these problems with energy saving, low operating cost and simple structure. The practical application of this is desired.

Patent Document 1 discloses an invention based on the vacuum distillation principle shown in FIG. 3 which is the basis of the present invention. The operation method of the reduced-pressure boiling seawater desalination apparatus of FIG. 3 is as follows.
The seawater tower 11 standing in the seawater 34 accommodated in the seawater tank 16, the freshwater tower 12 standing in the freshwater 51 accommodated in the freshwater tank 17, the seawater tower 11 and the freshwater tower 12, Are constituted by a communication pipe 13 for hermetically connecting them. A heating means 19 for maintaining a constant seawater temperature is installed at the upper part of the seawater tower 11, and a cooling means 14 is arranged in the upper space 27.

Seawater is pumped up from the sea until the liquid level height H ₁ inside the sea water tower 11 reaches about 10 m, and then the fresh water tower 12 enters the fresh water tower 12 until the height H ₂ of the liquid level 42 inside the fresh water tower 12 reaches about 10 m. Add fresh water.
Next, the air remaining in the top space 27 of the seawater tower 11, the top space 44 of the fresh water tower 12 and the communication pipe 13 is exhausted, and a Trichelli vacuum (which is not strictly a Trichelli vacuum because seawater is used instead of mercury). Hereinafter, this is called for convenience).

Next, the seawater pumped from the sea is passed through the tube 62 of the finned tube heat exchanger (cooling means) 14 and passed near the liquid surface at the top of the seawater tower 11. When the temperature detected by the temperature sensor 20 is lower than the set temperature, the heating means 19 heats. As a result, a stable boiling state is maintained near the liquid level, the upper space 27 of the seawater tower 11 is always filled with saturated water vapor pressure, and the water vapor is condensed exclusively on the surface of the fins 61 of the fin tube heat exchanger 14. The condensed water flows as fresh water into the fresh water tower 12 via the communication pipe 13 and is collected in the collection tank 55.
However, in this patent document 1, although the heat of condensation of water vapor is efficiently recovered, there is no technical idea of recovering the kinetic energy inherent in the water vapor.

Non-patent document 1 discloses, for example, the invention shown in FIG. 4 as an invention for obtaining fresh water by distilling seawater under reduced pressure, rotating a turbine with generated steam to generate power, and condensing steam after power generation. The operation principle of the reduced-pressure boiling seawater desalination apparatus with power generation function of FIG. 4 is as follows.
The reduced-pressure boiling seawater desalination apparatus 80 with a power generation function includes a flash evaporator 81, a condenser 82, a turbine 83, and a generator 84. In this system, the flash evaporator 81, the turbine 83, and the condenser 82 are evacuated in advance by the vacuum pump 85.

Next, warm seawater is introduced into the flash evaporator 81 by the warm seawater pump 85 and evaporated to obtain water vapor. This steam is sent to the turbine 83 as a working fluid, and the turbine 83 is rotated to generate power. The expanded water vapor discharged from the turbine 83 enters the condenser 82 and is cooled by the cold seawater pumped from the deep sea by the cold seawater pump 87 to become fresh water.
In the invention of Reference 2, although the vacuum is used, the Trichelle's vacuum is not used, and there is no specific disclosure about the devices such as the flash evaporator 81 and the condenser 82.

Patent Document 2 discloses the invention of FIG. 5 in which power is generated by a turbine generator in the process of forming a Triceri vacuum to distill seawater to obtain fresh water. In FIG. 5, reference numerals 92 and 94 are seawater, and reference numerals 93 and 95 are fresh water. In the decompression vessel 90, water vapor is generated in the evaporation unit 90a, and the water vapor is condensed in the condensing unit 90b. Therefore, the water vapor flows from the evaporation unit 90a to the condensing unit 90b. Utilizing this water vapor flow, a turbine generator 89 is installed between them to generate power and distill seawater.
The invention using the turbine generator disclosed in Patent Document 2 is very unclear because there is no specific description of the specific configuration of the power generation system and the operation method.

JP2013-413124A WO2010 / 087042

Saga University Ocean Energy Research Center Home Page ・ NELHA (Hawaii State Renewable Energy Laboratory) Hawaii 210 kW open cycle experimental equipment OTEC (1993) constructed on the Kona coast of Hawaii Island ・ Saga University OTEC experimental equipment-Shiranui No. 1 (April 1974)

In the reduced-pressure boiling seawater desalination system that uses the Torrichelli vacuum, the boiling point of the seawater is lowered using the Torrichelli vacuum, and the seawater pumped up for cooling is used as evaporation seawater after the temperature has been raised by heat exchange. It is an energy-saving type desalination device. However, this alone is not sufficient for energy recovery. Non-Patent Document 1 and Patent Document 2 described above disclose an invention in which kinetic energy of water vapor pressure generated by evaporation of seawater is generated by a turbine generator to be recovered as electric energy. However, an efficient energy recovery method using turbine power generation is not easy, but these two prior arts do not specifically disclose the turbine generator section.

In the present invention, it is recognized that the turbine generator incorporated in the reduced-pressure boiling seawater desalination apparatus has the following technical problems.
(1) Although a low-pressure radial turbine generator is used as the generator, it is necessary to restore pressure by suppressing flow loss to ensure efficiency.
(2) In order to ensure good heat exchange in the heat exchanger, the steam flow discharged from the turbine needs to collide uniformly with the entire finned tube heat exchanger.

In the reduced-pressure boiling seawater desalination apparatus of the present invention, by using the Triceri vacuum, the seawater is boiled at a temperature close to room temperature, and the generated steam is used to drive the turbine generator to generate power. Is cooled and condensed to obtain fresh water. In addition, the gravity difference is used as much as possible for the transportation of seawater and fresh water.

The reduced-pressure boiling seawater desalination apparatus with power generation function according to claim 1 of the present invention includes a seawater tower standing in seawater, a freshwater tower standing in freshwater, and these two sealed containers. A communication pipe provided in communication with the upper part and a heating means for boiling the seawater under reduced pressure are provided at the upper part of the seawater tower. In addition, a turbine power generation system is arranged in the seawater evaporation section at the top of the seawater tower, and cooling means (fin tube heat exchanger (condenser) and condensate tray for collecting condensed water) for cooling the steam after power generation are provided. Provided.

Of these, the seawater tower is a long airtight container that is installed in a seawater tank filled with seawater, shut off from the atmosphere, with its upper end sealed and its lower end released into seawater. It is an airtight container, and the liquid level in the seawater tower is maintained lower than the communication position between the seawater tower and the communication pipe.
The inside of the container is filled with seawater except for the upper part, and the upper space where seawater does not exist is formed with a Trichelli vacuum, and almost no air is present and is filled with saturated steam of seawater. The height of the liquid level inside the seawater tower from the level of the seawater tank is balanced with the atmospheric pressure and is about 10 m.

The fresh water tower is a long airtight container standing in a fresh water tank filled with fresh water. The upper end is sealed and the lower end is released into fresh water. The container is filled with fresh water except at the top. In the upper space where there is no fresh water, a Trichelli vacuum is formed, and there is almost no air, and it is filled with saturated steam of fresh water. The height of the liquid level inside the fresh water tower from the surface of the fresh water tank is balanced with the atmospheric pressure and is about 10 m.

On the other hand, the communication pipe is a pipe that connects the upper part of the seawater tower and the upper part of the freshwater tower. The connection part between the communication pipe and the seawater tower has an airtight structure, and the connection part between the communication pipe and the freshwater tower is also airtight. Connected.
In addition, a cooling means that partially enters the communication pipe is installed in the upper space of the seawater tower. The cooling means uses seawater as a cooling medium to cool the water vapor evaporated in the upper space of the seawater tower and let it flow down into the communication pipe.
The cooling means is composed of a slit or a fin tube heat exchanger (condenser) provided with a disturbing element and a condensate tray, and efficiently cools by passing seawater for cooling.
Further, the cooling seawater flowing through the cooling means is discharged to the upper position of the seawater tower.

Seawater heating means is installed in the vicinity of the cooling seawater discharge part. The seawater heating means includes a temperature sensor that measures seawater temperature, a heater that heats seawater, and heater heating when the seawater temperature measured by the temperature sensor is lower than a predetermined temperature, and a heater when the seawater temperature is equal to or higher than the predetermined temperature. It consists of a temperature controller that controls to turn off the power.
The heating means is not limited to a heater, and may be a solar heat absorption device that absorbs solar heat, or a combination thereof. However, the installation position of the solar heat absorption device is limited to the place where the heat insulating material of the seawater tower is not installed.

At first, seawater is sampled from the sea for cooling, and is put into the reduced-pressure boiling seawater desalination device as seawater for cooling. It is heated and reaches the boiling temperature at the discharge. Seawater is used as raw water for steam generation after being used as cooling water, but since it is heated to the boiling temperature at the heat exchanger discharge, the seawater heating means uses the condensation heat recovered above from the heat of evaporation. Seawater can be easily evaporated by supplying only the amount obtained by subtracting.

An open power generation system using water vapor as a working fluid or a closed power generation system using ammonia as a working fluid is installed at the upper part of the seawater tower, and converts the kinetic energy and condensation energy of the working fluid into electrical energy.

Further, the relative positional relationship between the liquid level height position inside the seawater tower and the liquid level height position inside the fresh water tower does not necessarily need to be matched, and any of them may be at a high position. However, if the seawater tower liquid level is higher than the fresh water tower liquid level, it is convenient for the fresh water to flow down and to be recovered. As a result, the fresh water obtained by cooling the water vapor naturally flows down into the fresh water tower. The liquid level in the fresh water tower is maintained at a constant height while being balanced with the atmospheric pressure because the water vapor pressure determined by the fresh water temperature in the fresh water tower is constant. Therefore, the same amount of fresh water in the fresh water tower as fresh water newly produced by condensation of water vapor is pushed out into the fresh water tank from the lower open end. The amount of fresh water pushed out at this time is the amount of fresh water produced by the vacuum boiling seawater desalination apparatus with the power generation function.

The invention described in claim 2 is a reduced-pressure boiling seawater desalination apparatus with a power generation function incorporating an open power generation system.
A turbine chamber in which steam generated by the heating means is induced, a radial turbine installed in the turbine chamber and driven to rotate using steam as a working fluid, and a synchronous generator connected to the rotating shaft of the radial turbine are provided. The turbine chamber is further connected to a bent diffuser, which induces steam to impinge on the entire fin tube heat exchanger fins within a predetermined angular range.

Thereby, the water vapor evaporating from the seawater heated and boiled by the seawater heating means is guided to the water vapor inlet port that fills the evaporation chamber and continues to the turbine chamber, and is ejected from the outlet port of the turbine chamber to rotate the turbine. A generator is directly connected to the rotating shaft of the turbine, and the kinetic energy of water vapor is converted into electrical energy.

Since the turbine chamber is provided adjacent to the evaporation chamber in the upper part of the seawater tower, the flow loss of the water vapor flow is suppressed to a minimum, and the water vapor discharged from the turbine chamber is bent and the flow loss is suppressed by the diffuser to restore the pressure. In addition, the water vapor flow is induced to uniformly collide with the entire fin tube heat exchanger fin installed in the condensing chamber at an incident angle of 20 ° to 40 °. It moves between the fins while contacting the surface, and water vapor is condensed on the fin surface as water droplets.

The invention described in claim 3 is a reduced-pressure boiling seawater desalination apparatus with a power generation function incorporating a closed power generation system.
The closed power generation system includes an evaporator, a condenser, a radial turbine, a pump and piping connecting these, and a generator. The evaporator is installed in the seawater where the heating means is installed, and ammonia is vaporized by the heat received from the seawater heated by the heat of condensation of water vapor. Since ammonia turned into gas is ejected to the blades of the radial turbine, the radial turbine is rotated, and a synchronous generator connected thereto generates power. Since the synchronous generator is directly connected to the rotating shaft of the radial turbine, it is easy to reduce the size of the generator, but in some cases, a gear is inserted between the rotating shaft of the radial turbine and the rotating shaft of the generator to convert the rotational speed. May be performed.

The ammonia vapor that has passed through the radial turbine reaches a condenser where it is cooled by seawater and returns from gas to liquid. The liquefied ammonia is again transported to the evaporator by a pump, and the above process is repeated.
Since the closed power generation system of the present invention is seawater in which the heat source for vaporizing ammonia is heated, the invention is particularly effective when the recovery of latent heat of condensation of water vapor performed in a finned tube heat exchanger is ideally advanced. Become.

The invention described in claim 4 is a reduced-pressure boiling seawater desalination apparatus with a power generation function incorporating a closed power generation system.
The closed power generation system includes an evaporator, a condenser, a radial turbine, a pump and piping connecting these, and a generator. The evaporator is an upper space (condensing chamber) of the seawater tower and is installed upstream of the finned tube heat exchanger, and ammonia is vaporized by the heat of condensation of water vapor. The gaseous ammonia is jetted to the blades of the radial turbine and generated by a synchronous generator connected to the radial turbine. Since the synchronous generator is directly connected to the rotary shaft of the radial turbine, it is easy to reduce the size of the generator.

The ammonia vapor that has passed through the radial turbine reaches a condenser where it is cooled by seawater and returns from gas to liquid. The liquefied ammonia is again transported to the evaporator by a pump, and the above process is repeated.
The closed power generation system of the present invention has an advantage that the condenser energy can be reliably recovered from the water vapor because the evaporator is installed upstream of the finned tube heat exchanger.

The depressurized boiling type seawater desalination method with a power generation function according to claim 5 is configured to heat seawater pumped from the sea to a temperature higher than the sea temperature, evaporate water in a vacuum, create a steam stream, This is a vacuum boiling type seawater desalination method with a power generation function in which steam is cooled and recovered as fresh water after a turbine generator is driven to generate power.
The main components of the device are as follows.

(1) A seawater tower that is cut off from the atmosphere and is erected in seawater in a seawater tank, with the bottom open to seawater.
(2) A fresh water tower that is cut off from the atmosphere, is erected in fresh water in a fresh water tank, and has a bottom open to fresh water.
(3) A communication pipe in which one side communicates with the upper part of the seawater tower while maintaining airtightness, and the other communicates with the freshwater tower while maintaining airtightness.
(4) A heating means for evaporating seawater.
(5) A turbine chamber into which steam produced by heating means is introduced.
(6) A turbine generator that is installed in the turbine chamber and is driven to rotate by steam to generate electric power.
(7) A curved diffuser that guides water vapor discharged from the turbine chamber.
(8) A fin-tube heat exchanger (condenser) that condenses water vapor into fresh water.
(9) A condensate tray that collects fresh water and flows it down into the communication pipe.

In the present invention, first, a water vapor stream is created by heating to a temperature above the sea temperature with a heating means under reduced pressure. Next, the steam flow is guided to the turbine chamber, ejected from the outlet of the turbine chamber, and the turbine is rotated by this energy to cause the turbine generator to generate electric power.
After that, the water vapor is bent and guided by the diffuser from the turbine chamber to the finned tube heat exchanger, cooled and condensed on the fin surface of the finned tube heat exchanger to become fresh water. The present invention is a seawater desalination method in which a Tricherry vacuum, a turbine generator, and a finned tube heat exchanger are incorporated into one apparatus, thereby minimizing the energy consumption required for freshwater production.

The present invention is a method for minimizing the energy required for desalination (electrical energy input to the apparatus from the outside), which is the greatest problem when desalinating seawater by a distillation method.
In the present invention, minimization is achieved by the following method.

(1) By using the Tricherry vacuum, the water was boiled at a temperature close to the seawater temperature, and the energy required for heating the seawater was minimized.
(2) In the open power generation system, the evaporation chamber and the turbine chamber are directly connected, and the turbine chamber and the condensing chamber are bent and connected by a diffuser to minimize the flow loss of the water vapor flow.
(3) In the closed power generation system, the radial turbine can be downsized by increasing the working pressure of the working fluid.
(4) The steam flow was made to collide with the fins of the fin-tube heat exchanger at an incident angle of 20 ° to 40 ° to maximize the heat exchange efficiency.
(5) Since the cooling water heated by heat exchange is heated as raw seawater, the heat energy for heating to the boiling temperature is minimized.
(6) Since the electric power generated by the turbine generator is used as a heat source for boiling seawater, the electric power procured from the outside was minimized.
As described above, the reduced-pressure boiling seawater desalination apparatus with a power generation function according to the present invention can produce fresh water with energy saving and stably.

Configuration explanatory diagram of the reduced-pressure boiling seawater desalination apparatus with power generation function of the present invention (first embodiment) Illustration of the principle of energy recovery in the present invention Configuration diagram of the vacuum boiling seawater desalination system Principle diagram of non-patent document 1 vacuum boiling seawater desalination equipment with power generation function Conceptual diagram of the vacuum boiling seawater desalination device with power generation function of Patent Document 2 Closed-type vacuum boiling seawater desalination system (second embodiment) Closed type vacuum boiling seawater desalination system (third embodiment)

The overall configuration of the first embodiment of the reduced pressure boiling seawater desalination apparatus with power generation function of the present invention will be described with reference to FIG.
The reduced-pressure boiling seawater desalination apparatus 10 with a power generation function includes a seawater tower 11 erected in the seawater 34 accommodated in the seawater tank 16 and a freshwater tower erected in the freshwater 51 accommodated in the freshwater tank 17. 12 and a communication pipe 13 that connects the seawater tower 11 and the freshwater tower 12 in an airtight manner. A heating means 19 for maintaining a constant seawater temperature is installed in the upper part of the seawater tower 11, and a cooling means 14 is arranged in the condensing chamber 73 of the seawater tower 11. Furthermore, a heat insulating material 18 that surrounds and insulates the outer walls is attached to the upper outer wall portion of the seawater tower 11, the outer wall of the communication pipe 13, and the outer wall of the fresh water tower 12.

Next, the process from the start-up of this apparatus to the steady operation will be described with reference to FIG.
The valves 21, 22, 29, 31 arranged at the top and bottom and the side of the seawater tower 11 are opened, the valve 32 is closed, the pump 24 is operated, the seawater is pumped from the sea through the pipe 33, and the seawater tower 11 is filled with seawater. . When the seawater tank 16 is filled with seawater, the pump 24 is stopped and the valve 21 is closed. The pump 24 is restarted to inject seawater into the seawater tower. When the height H ₁ of the liquid level 26 reaches about 10 m, the valve 31 is closed and the pump 24 is stopped.

The valves 43, 45, 47 arranged above and below the fresh water tower 12 are opened, the pump 46 is operated while checking the flow rate with the flow meter 52, fresh water is supplied through the pipe 58, and fresh water is supplied into the fresh water tower 12. throw into. When the fresh water tank 17 is filled with fresh water, the pump 46 is stopped and the valve 45 is closed. Fresh water is injected into the fresh water tower is re-activated pump 46, closing the valve 52 when the height H ₂ of the liquid surface 42 was about 10 m, to stop the pump 46.

When the valves 22 and 43 are closed and the valves 21 and 51 are opened, the pressure in the top space 27 of the seawater tower 11, the top space 44 of the fresh water tower 12 and the communication pipe 13 decreases depending on the water heads H ₁ and H ₂ . Close to vacuum.
Next, in order to remove the air remaining in the condensing chamber 73 of the seawater tower 11, the top space 44 of the freshwater tower 12 and the communication pipe 13, the valve 39 is opened and the vacuum pump 15 is operated. The inside of the communication tube 13 is evacuated. The degree of vacuum at this time can be confirmed with the vacuum gauge 28. Thereby, a Trichelli vacuum is formed inside the seawater tower and inside the fresh water tower. It should be noted that the seawater and freshwater towers boil in the seawater and freshwater just before reaching the Torrichelli vacuum.

When the Trichelli vacuum is formed, the valve 39 is closed and the vacuum pump 15 is stopped. At this time, the liquid level 26 in the seawater column 11 is made from the liquid surface 35 of the sea water tank 16 and the height of the _{H 1, H 1} is about 10 m. Moreover, the height of the liquid level 42 in the fresh water tower 12 becomes the height of H ₂ from the liquid level 53 of the fresh water tank 17, and H ₂ becomes about 10 m.

Next, with the valve 31 closed, the valves 29 and 32 are opened, and the seawater pumped from the sea while measuring the flow rate with the flow meter 36 is passed through the tube 62 of the finned tube heat exchanger (cooling means) 14. , And discharged near the liquid surface at the top of the seawater tower 11. Further, a temperature sensor 20 is installed in the vicinity of the liquid surface, and when the temperature detected by the temperature sensor 20 is lower than the control temperature set in the heating means 19, the heating means 19 is heated by PID control. 23 is operated to heat the seawater 25 near the liquid surface of the seawater tower 11. As a result, a stable boiling state is maintained near the liquid level, and the evaporation chamber 27 is always filled with saturated water vapor pressure.

The water vapor filled in the evaporation chamber 27 flows into the turbine chamber 71 from the water vapor introduction port 76 and causes the radial turbine 72 to rotate vigorously. A generator 74 is directly connected to the rotary shaft 78 of the radial turbine 72, and power is generated by the rotation of the radial turbine 72. Thereby, the kinetic energy of water vapor | steam is converted into an electrical energy. The electric power generated here is used as an auxiliary power source for the heating means 19.

The steam that has finished generating electricity in the turbine chamber 71 is bent from the steam outlet 75 and discharged to the diffuser 30. The bending diffuser 30 suppresses the flow loss and recovers the pressure, and at the same time guides the water vapor flow to the finned tube heat exchanger 14 installed in the condensing chamber 73. The main function of the bending diffuser 30 is to make the water vapor flow collide with the fins 61 of the finned tube heat exchanger 14 in the range of incident angles of 20 ° to 40 °. Accordingly, the water vapor flow is accompanied by turbulent flow, and is uniformly distributed between the fins 61 of the fin tube heat exchanger 14 and efficiently condenses the water vapor on the surfaces of the fins 61 while flowing.

Since the outer wall surface of the upper part of the seawater tower 11 is surrounded by a heat insulating material, the water vapor is not condensed on the wall surface, and the water vapor is condensed exclusively on the surface of the fin 61 of the fin tube heat exchanger 14. Further, since the cooling water is continuously supplied to the finned tube heat exchanger 14 by the pump 24, the condensing capacity is maintained.
The float member 60 that covers the liquid surface of the communication pipe 13 is held by a method of hanging from the upper part of the communication pipe 13, and suppresses fresh water from re-evaporating into the condensation chamber 73.

In these series of operations, boiling and evaporation of seawater and cooling and condensation of the generated water vapor proceed simultaneously in the evaporation chamber 27 and the condensation chamber 73, so that the volume and pressure of the evaporation chamber 27 and the condensation chamber 73 are kept substantially constant. Be drunk. In addition, these series of operations do not require artificial control and all proceed autonomously.
Moisture condensed on the surface of the fin 61 is dropped on the receiving tray 63 immediately below to become fresh water and flows down into the communication pipe 13. Since the liquid level in the communication pipe is kept constant, the fresh water that flows down is sequentially pushed downward in the fresh water tower 12, reaches the fresh water tank 17, gets over the weir 54 of the fresh water tank 17, and reaches the recovery tank 55. .

Fresh water in the collection tank 55 is taken out while the valve 57 is opened and the flow rate is measured by the flow meter 56.
The amount of seawater supplied from the pump 24 can be confirmed with the flow meter 36. However, when the amount of seawater evaporated in the evaporation chamber 27 of the seawater tower 11 is larger than the amount of seawater, It is pushed away to reach the seawater tank 16, gets over the weir 40 and is discharged from the sub-storage tank 37 to the outside.

For the first embodiment of the present invention shown in FIG. 1, a rough estimation of the energy balance of the entire apparatus will be described in the following steps 1 to 4.
Step 1: Energy required for vaporizing seawater FIG. 2 is an explanatory diagram of the principle of energy recovery in the present invention. After seawater is evaporated in the evaporation tank 64, a steam flow created by evaporation flows into the turbine chamber 71 and generates electricity. It flows into the condensing tank 65.
Here, the diameter of the evaporation tank 64 is D ₁ = 5 [m], and the height H of the evaporation chamber 27 is 0.2 [m].
The temperature of the seawater 25 is 25 [° C.], and this is heated to 30 [° C.] to be steam.
Diameter D ₂ of cross section of turbine chamber 71 = 0.5 [m]

The temperature in the evaporation chamber 27 is 30 [° C.], the vapor pressure is about 30 [mmHg], and the surface of the seawater 25 is maintained at 30 [° C.]. Also, under this situation, 31.4 [kg / m ² · min] of seawater continues to evaporate into the evaporation chamber (reference: Encyclopedia 38, 2004 Ikuo Hashimoto).
The heating and evaporation energy of seawater required to maintain this equilibrium state is the sum of the heating energy for raising the temperature of seawater corresponding to the amount of evaporation from 25 [° C] to 30 [° C] and the evaporation (vaporization) heat. Become. Of these, the heating energy can be calculated as 216 [kWh / φ5 m · h]. The heat of evaporation will be described in step 3.

Step 2: Since the amount of water vapor produced in the power generation energy evaporation chamber 27 is 31.4 [kg / m ² · min] under the conditions of 30 [° C.] and 30 [mmHg], the amount of water vapor produced by this apparatus Is about 10.3 [kgf / φ5 m · s].
On the other hand, the specific volume of saturated water is 0.001 [m ³ / kg] under the conditions of 30 [° C.] and 30 [mmHg]. 7 [m ³ / kg] (heat transfer engineering data revision 5th Japan Society of Mechanical Engineers, Maruzen 2009/05).
Since the total amount of water vapor in the evaporation chamber 27 is about 10.3 [kgf / φ5 m · s], when converted to volume, it becomes 25 [m ³ / s], which is the volume of water vapor generated every second.

Further, since the inner diameter of the turbine chamber is 0.5 [m], the flow velocity of the water vapor flow flowing through the turbine chamber is 50 [m / s]. The kinetic energy of the water vapor flow is calculated as 1.310 [kw / s] because the water vapor density is 0.412 [kgf / m ³ ].
Here, the case where the conversion efficiency of the radial turbine generator is set to 2 [%] will be described first (the case where the conversion efficiency is set to 2.7 [%] will be described later in paragraph [0047]). When 2% of the previous 1.310 [kw / s] is recovered as electric energy by the radial turbine generator, the recovered power amount is about 94 [kWh].

Step 3: Recovery of heat energy by fin tube heat exchanger In the fin tube heat exchanger, 30 [° C.] water vapor is cooled and condensed to 25 [° C.] and latent heat is released. The thermal energy recovered here can be grasped as the difference from the heat of evaporation absorbed in step 1.
The heat of vaporization of water is 580.2 [kcal / kg], and the heat of condensation is 583.1 [kcal / kg]. If all the heat of condensation is absorbed by the cooling water when water vapor condenses, the amount of heat is recovered by 2.9 [kcal / kg] corresponding to the difference between the two.
Since the amount of water vapor generated per unit time is 31.4 × 60 [kg / m ² · h], the recovered energy due to the difference between the latent heat and the evaporation heat is +91 [kWh / φ5 m · h].

Step 4: Overall energy balance (1) Heating energy of seawater: -216 [kWh / φ5m · h]
(2) Power generation energy: +94 [kWh]
(3) Energy counted by condensation heat: +91 [kWh / φ5m · h]
The sum of the above (1) to (3) is −31 [kWh].
Therefore, in this system, fresh water of about 1,884 [kg] can be produced with the power consumption of 31 [kWh] per hour.

If the conversion efficiency of the radial turbine generator is calculated again as 2.7 [%], the recovered power amount is about 127 [kWh], and the overall energy balance is as follows.
(1) Heating energy of seawater: -216 [kWh / φ5m · h]
(2) Power generation energy: +127 [kWh]
(3) Energy counted by condensation heat: +91 [kWh / φ5m · h]
The sum of (1) to (3) is +2 [kWh], and approximately 1,884 [kg] of fresh water can be produced every hour without external power supply.

The power generation system used in the present invention shown in FIG. 1 is water vapor obtained by evaporating seawater as the working fluid that rotates the turbine. Since the working fluid is discharged outside the turbine chamber, the power generation system generally called an open type is used. being classified. However, in this invention, it can be set as the closed type electric power generation system which uses ammonia for a working fluid. FIG. 6 shows a second embodiment of the closed-type reduced-pressure boiling seawater desalination apparatus.

A difference from FIG. 1 is a closed power generation system 100. In this closed type power generation system, ammonia is used as a working fluid. Ammonia is vaporized by the evaporator 103 and rotates the radial turbine 101. Thereby, the generator 102 directly connected to the radial turbine 101 generates power. Next, the ammonia gas is liquefied by the condenser 104, and is transported in the ammonia gas pipe 109 by the pump 105 in the direction of the arrow, where it reaches the evaporator 103 again and is superheated and vaporized. The condenser 104 is cooled by a seawater pipe 108 branched from the seawater pipe 33 by a valve 107, and the seawater used for cooling is used as the seawater 25 for generating steam.

Ammonia is a harmful substance, but there is no problem in safety because it is used closed in the system. In this power generation system, the vapor pressure of ammonia is 1.00 [MPa] at 25 ° C. and 1.17 [MPa] at 30 ° C. Therefore, the differential pressure between 25 ° C. and 30 ° C. is 0.17 [MPa], and the radial turbine generator 101 can be driven with this differential pressure.
In the second embodiment, a system that is particularly effective when the heat energy recovery in the fin tube heat exchanger 14 with slits or disturbance elements functions sufficiently and heating of the seawater 25 by the heating means 19 is not necessarily required. The power generation energy can be used in addition to heating the seawater 25.

FIG. 7 shows a closed-type reduced-pressure boiling seawater desalination apparatus according to the third embodiment.
FIG. 7 is a modification of FIG. 6, and the evaporator 103 is disposed in the condensation chamber 73. Therefore, the evaporator 103 and two of the fin tube heat exchanger 14 with a slit or a disturbance element are arrange | positioned in a condensing chamber. As a result, the condensation energy of water vapor generated by heating the seawater 25 is recovered in two stages of the evaporator 103 and the slit or finned tube heat exchanger 14 with a disturbing element.

In this embodiment, the heat of condensation of the water vapor is reliably recovered, so that the heating temperature of the seawater 25 can be raised relatively easily. For example, when the seawater temperature is 35 ° C., the vapor pressure of ammonia at 35 ° C. is 1.35 [MPa]. The differential pressure between the vapor pressure of ammonia at 25 ° C. and 35 ° C. is 0.35 [MPa], and the driving of the radial turbine generator 101 is further facilitated as compared with the seawater temperature of 30 ° C.

DESCRIPTION OF SYMBOLS 10 Vacuum boiling type seawater desalination apparatus 11 Seawater tower 12 Freshwater tower 13 Communication pipe 14 Fin tube type heat exchanger with a slit or a disturbance element 15 Vacuum pump 16 Seawater tank 17 Freshwater tank 18 Heat insulating material 19 Heating means
DESCRIPTION OF SYMBOLS 23 Heater 25 Seawater 27 Evaporating chamber 41 Fresh water 64 Evaporating tank 65 Condensing tank 71 Turbine chamber 72 Radial turbine 73 Condensing chamber

Claims (5)

Seawater pumped up from the sea is heated to above the sea temperature, the water is evaporated in a vacuum, and the turbine generator is driven using the water vapor and heated seawater produced by the evaporation. A reduced-pressure boiling seawater desalination apparatus with a power generation function for cooling the water vapor and collecting it as fresh water,
A seawater tower that is cut off from the atmosphere and standing in seawater, the bottom of which is opened in the seawater of the seawater tank in which seawater is stored;
A fresh water tower that is cut off from the atmosphere and is erected in fresh water in a fresh water tank, and whose bottom is opened into the fresh water;
One communicating with the upper part of the seawater tower while maintaining confidentiality, and the other communicating with the freshwater tower while maintaining confidentiality;
Heating means for evaporating the seawater;
A turbine power generation system that generates power by being disposed in the seawater evaporation section at the top of the seawater tower;
Cooling means for cooling the water vapor, condensing it into fresh water, and flowing down into the communication pipe,
The cooling means is composed of a fin tube heat exchanger (condenser) and a condensate tray, and is disposed in the upper space of the seawater tower,
A reduced-pressure boiling seawater desalination apparatus with a power generation function, wherein a liquid level in the seawater tower is lower than a communication position between the seawater tower and the communication pipe. The turbine power generation system is an open power generation system,
A turbine chamber for introducing water vapor evaporating from the upper part of the seawater tower;
A radial turbine installed in the turbine chamber;
A synchronous generator that is directly connected to the rotary shaft of the radial turbine and is rotationally driven;
A bent diffuser for guiding the water vapor from the turbine chamber to a cooling means;
The water vapor discharged from the turbine chamber is uniformly guided to the entire fins of the finned tube heat exchanger by a bent diffuser and collides with the fins of the finned tube heat exchanger in a predetermined angle range. The reduced-pressure boiling seawater desalination apparatus with a power generation function according to claim 1. The turbine power generation system is a closed power generation system,
An evaporator installed in seawater in which the heating means is installed;
A condenser that diverts and cools part of the cooling seawater used in the finned tube heat exchanger;
A radial turbine using ammonia as a working fluid;
The reduced-pressure boiling seawater desalination apparatus with a power generation function according to claim 1, comprising a synchronous generator directly connected to a rotary shaft of the radial turbine and driven to rotate. The turbine power generation system is a closed power generation system,
An evaporator installed in an upper space of the seawater tower;
A condenser that diverts and cools part of the cooling seawater used in the finned tube heat exchanger;
A radial turbine using ammonia as a working fluid;
The reduced-pressure boiling seawater desalination apparatus with a power generation function according to claim 1, comprising a synchronous generator directly connected to a rotary shaft of the radial turbine and driven to rotate. Seawater pumped from the sea is heated to above the sea temperature to evaporate water in a vacuum, and a turbine generator is driven by steam generated by evaporation to generate power. A vacuum boiling type seawater desalination method to be recovered as
A sea water tower that is cut off from the atmosphere and is erected in seawater in a seawater tank, and whose bottom is open to the seawater;
A fresh water tower that is cut off from the atmosphere and is erected in fresh water in a fresh water tank, and whose bottom is open to the fresh water;
One communicating with the upper part of the seawater tower while maintaining airtightness, and the other communicating with the freshwater tower while maintaining airtightness;
Heating means for evaporating the seawater;
A turbine chamber into which steam produced by the heating means is introduced;
A turbine generator that is installed in the turbine chamber and is rotationally driven by the steam to generate electricity;
A curved diffuser for guiding the water vapor discharged from the turbine chamber;
A finned tube heat exchanger (condenser) that condenses the water vapor into fresh water;
A condensate tray that collects the fresh water and causes it to flow down into the communication pipe, and
Introducing water vapor evaporated by the heating means into the turbine chamber;
Turn the turbine to cause the turbine generator to generate power,
Next, the water vapor is guided from the turbine chamber to the finned tube heat exchanger by the bent diffuser,
A reduced-pressure boiling seawater desalination method with a power generation function for producing fresh water by condensing in the finned tube heat exchanger.