WO2002073099A1

WO2002073099A1 - Solar thermal system with solar pond and method of maintaining solar pond

Info

Publication number: WO2002073099A1
Application number: PCT/JP2002/002210
Authority: WO
Inventors: Mikio Kinoshita
Original assignee: Mikio Kinoshita
Priority date: 2001-03-12
Filing date: 2002-03-08
Publication date: 2002-09-19
Also published as: JPWO2002073099A1; US20040098998A1

Abstract

A solar thermal system, comprising a solar pond (10) for accumulating salt water heated by solar radiation and a moisture supply device (20) allowing the vapor evaporated from the water having impurities such as sea water to be absorbed by the salt water; a method of maintaining the solar pond; and a method of forming the solar pond; the system, wherein the moisture supply device may have an absorbing heat pump for receiving the supply of the salt water and the water having the impurities, and the salt water with excellent cleanliness is circulated to the solar pond by the operation of the moisture supply device, whereby scale deposit and propagation of algae in the solar pond can be prevented.

Description

Description Solar thermal system with solar pond and method for maintaining solar bond

The present invention relates to a solar thermal system having a solar bond, a method for maintaining a solar bond, and a method for forming a solar bond. Background art

Solar pond is known as a type of solar thermal system. The solar pond accumulates clear brine with a defined concentration distribution. The lower layer of the brine is heated to a high temperature by solar radiation. The concentration of the lower layer of the solar pound is higher than the concentration of the upper layer. For this reason, even if the lower brine is heated to a high temperature, convection does not occur, and the heat transfer from the hot lower layer to the cold upper layer is extremely small. This results in hot brine in the lower layer of the solar pond.

Diffusion of salts occurs due to the difference in concentration of the salt water and the like. In order to suppress a change in the concentration distribution of the salt water due to the diffusion of the salt, water is supplied to an upper portion of the salt water. Further, the lower layer of the brine is concentrated. Thus, it is important to properly replenish the upper brine and concentrate the lower brine in maintaining the solar pond. In particular, when the upper part of the solar bond is open, a large amount of water needs to be supplied because water evaporates in the upper layer.

Cleanliness is required for the quality of water to be replenished. For example, If the supplied water contains impurities such as nutrients, undesired microorganisms and algae will proliferate, resulting in reduced transparency. In order to reduce the cost of water supply, it is required in the prior art solar pond to supply water having a predetermined cleanliness at low cost.

In addition, when seawater or the like is used as such salt water, there is a problem in that scale is deposited as the seawater is concentrated.

The present invention has been made in view of the above, and one object of the present invention is to solve the above problems and other problems. It is another object of the present invention to provide a method for maintaining solar pounds and solar bonds that is easy to maintain. Yet another object of the present invention is to provide a solar thermal system having a solar pond that is easy to maintain. Still another object of the present invention is to provide a solar heat system having a solar bond that can use inexpensive seawater as a raw material for catching water, and a method for maintaining the solar bond. Yet another object of the present invention is to reduce costs in forming solar ponds. Disclosure of the invention

According to one embodiment of the present invention, a novel solar thermal system is provided. The solar thermal system includes a solar pond for storing salt water heated by solar radiation, and a water providing device for absorbing water vapor evaporated from water containing impurities into the salt water. The moisture providing device may include an absorption heat pump that receives the supply of the salt water and the water having the impurities. The solar thermal system may further comprise a concentrator for concentrating the salt water. According to another embodiment of the present invention, a method maintain _ό the solar pounds of how to maintain a novel solar bond is provided comprising a step of storing the brine having a predetermined concentration distribution of solar Bond, Absorbing the water vapor evaporated from the water having impurities into the salt water. The method for maintaining the solar bond may further include a step of concentrating the salt water.

According to yet another embodiment of the present invention, a method for forming a novel solar bond is provided. The method of forming the solar pond includes a step of dissolving a solid salt with an unsaturated salt water, a step of supplying the salt water in which the solid salt is dissolved to a water supply device, and a step of dissolving impurities in the water supply device. Absorbing the water vapor evaporated from the water containing the substance into the salt water in which the solid salt is dissolved, and refluxing a part of the salt water absorbing the water vapor evaporated from the water containing the impurities to the solid salt. A step of further dissolving the solid salt, and a step of sending a residue of the salt water having absorbed water vapor evaporated from the water having impurities to a solar pond. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a conceptual diagram illustrating a solar thermal system according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating the layered structure of salt water accumulated in the solar pond illustrated in FIG.

FIG. 3 is a conceptual diagram illustrating an example of the structure of the water supply device illustrated in FIG.

FIG. 4 is a conceptual diagram illustrating a solar thermal system according to another embodiment of the present invention. FIG. 5 is a conceptual diagram illustrating a flow of a solar thermal system according to still another embodiment of the present invention.

FIG. 6 is a conceptual diagram illustrating a flow of a solar thermal system according to still another embodiment of the present invention.

FIG. 7 is a conceptual diagram illustrating the inside of the cooling tank in FIG.

FIG. 8 is a conceptual diagram illustrating a flow of a solar thermal system according to still another embodiment of the present invention.

FIG. 9 is a conceptual diagram illustrating a flow in a method of forming a solar thermal system according to still another embodiment of the present invention.

FIG. 10 is a conceptual diagram illustrating the inside of a water supply device provided in a solar pond according to still another embodiment of the present invention.

FIG. 11 is a conceptual diagram illustrating a solar thermal system according to still another embodiment of the present invention.

FIG. 12 is a conceptual diagram illustrating the flow of a solar thermal system according to yet another embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

In order to describe the present invention in more detail, the present invention will be described with reference to the accompanying drawings. Throughout the figures, identical reference numbers indicate identical or corresponding parts.

A solar thermal system according to one embodiment of the present invention will be described with reference to FIG. FIG. 1 is a conceptual diagram illustrating a solar thermal system according to an embodiment of the present invention.

In FIG. 1, the solar thermal system has a solar pond 10, a moisture providing device 20, and a concentrating device 50. In the solar pond 10, clear salt water 70 accumulates. The solar pound 10 absorbs solar radiation. FIG. 2 is a conceptual diagram illustrating a layer structure of the salt water 70 accumulated in the solar cell 10. The salinity of the upper layer 70 A is lower than that of the lower layer 70 C. The salinity of the middle layer 70 B changes continuously. The salt concentration distribution of the middle layer 70B is controlled within a predetermined range so that convection due to heat does not occur. For this purpose, a concentration distribution adjusting means (not shown) may be provided. As salts, salts containing sodium chloride, magnesium chloride, and / or calcium chloride may be used. For example, the salt concentration of the upper layer 7OA and the salt concentration of the lower layer 70C may be 6 wt.% And 25 wt.%, Respectively. The temperature of the lower layer 70 C is higher than the temperature of the upper layer 70 A. The dashed lines in FIG. 2 conceptually illustrate the boundaries of the layers. A water supply pipe 40 and a drain pipe 42 are provided between the water supply device 20 and a water source (not shown). Water containing impurities is supplied to the water supply device 20 via the water supply pipe 40. For example, seawater, groundwater, river water, lake water, or sewage treatment water may be supplied as the water containing the impurities. The upper layer 70 A of the salt water 70 has a molar boiling point increase value larger than the molar boiling point increase value of the impurity-containing water.

Further, a water supply pipe 30 and a drain pipe 32 are provided between the salt water 70 and the water supply device 20. The salt water accumulated in the upper layer 7OA is supplied to the water supply device 20 via the water supply pipe 30.

In the water supply device 20, the water vapor evaporated from the water containing the impurities is absorbed by the salt water. Thereby, the salt water is diluted. The diluted salt water is returned to the upper layer of the salt water accumulated in the solar pond 10 via the drain pipe 32. Provide water to the salt water The water having the impurities thus concentrated is discharged out of the system via the drain pipe 42.

FIG. 3 is a conceptual diagram illustrating an example of the structure of the water supply device 20. In FIG. 3, the water supply device 20 is a kind of absorption heat pump. That is, the water supply device 20 includes a plurality of plates 22, a plurality of permeation members 24, and a plurality of permeation members 26.

Each osmotic member 24 is bonded on one surface of the plate 22. The salt water is supplied to each of the permeating members 24 via the water supply pipe 30. Each permeating member 24 permeates the salt water.

Each osmotic member 26 is glued on another side of the plate 22. Each permeation member 26 is arranged so as to face the permeation member 24. The water having the impurities is supplied to each of the permeating members 26 via the water supply pipe 40. Each permeating member 26 permeates the water containing the impurities. Each plate 22 does not penetrate the salt water. That is, non-volatile substances such as salts do not move between the water containing the impurities and the salt water.

As described above, the value of the molar boiling point rise of the salt water is larger than the value of the molar boiling point rise of the water having the impurities. Therefore, each penetrating member

The water vapor evaporating from the water having the impurities permeated into 26 diffuses in the void and is absorbed by the salt water permeated into the opposing permeation member 24. The water having the impurities concentrated by losing water is discharged through the drain pipe 42. The salt water diluted by absorbing water is supplied to the drain pipe.

It is discharged onto the surface of the brine 70 accumulated in the solar pond 10 via 32. The outlet of the discharge pipe 32 may be extended to the right side in FIG. Thus, the concentration of the upper layer of the salt water 70 is within a predetermined range. Is maintained in the enclosure. Since the non-volatile impurities in the water containing the impurities do not move into the salt water, the cleanliness of the salt water is maintained well. That is, the same cleanliness as that obtained by diluting the salt water with distilled water can be obtained.

In order to increase the diffusion amount of water vapor evaporated from the water containing the impurities, the inside of the water supply device 20 may be evacuated to a vacuum state using a vacuum system having a vacuum chamber (not shown). Instead, the inside of the water supply device 20 may be heated to a predetermined high temperature by using a heating system having a not-shown container having a heat insulating property. Furthermore, a heat exchange means (not shown) may be provided in order to increase the efficiency regarding heating. Further, the plurality of plates 22 may be arranged along a closed line.

The concentrating device 50 receives the supply of the salt water via a water supply pipe 60. The concentrator 50 condenses the salt water accumulated in the lower layer of the solar bond 10 and supplies the concentrated salt water to the lower layer of the solar bond via a drain pipe 62. Thereby, the concentration of the salt water accumulated in the lower layer of the solar pond 10 is maintained in a predetermined range.

The concentrating device 50 may be, for example, a multi-effect distillation device. In this case, a distilled water discharge pipe 64 is provided to discharge the generated distilled water. Further, the concentrator 50 may distill the salt water by utilizing the temperature difference between the upper layer and the lower layer of the salt water accumulated in the solar pond. The brine that accumulates in the upper layer of the solar pond 10 may be cooled by evaporation. Alternatively, the salt water may be concentrated by cooling with natural ventilation.

In the formation of the solar pond 10, first have a rich concentration Salt water may accumulate to a predetermined water level. Thereafter, the salt water may be supplied to the water supply device 20 to absorb the steam vaporized from the water containing the impurities into the salt water. By supplying the salt water diluted in this way to the solar bond 10, a salt water layer having the above concentration distribution may be formed.

FIG. 4 is a conceptual diagram illustrating a solar thermal system according to another embodiment of the present invention. In addition to the solar heat system illustrated in FIG. 1, a salt water desalination unit 80, a high-temperature heat source pipe 90 connected to the salt water desalination unit 80, and a cooling unit connected to the salt water desalination unit 80 And source pipe 92.

A heat transfer medium circulates through the high-temperature heat source tube 90. The high-temperature heat source pipe 90 supplies the heat energy of the salt water accumulated in the lower layer of the solar pond 10 to the salt water desalination apparatus 80.

A heat transfer medium circulates through the cooling source pipe 92. The cooling source pipe 92 releases the heat released from the salt water desalination unit 80 into the salt water stored in the upper layer of the solar pond 10. The upper layer is cooled by evaporative cooling, radiant cooling, and cooling by ventilation.

As the salt water desalination apparatus 80, a multi-effect distillation apparatus or a multi-stage flash evaporator may be used. The salt water desalination device 80 may desalinate the salt water supplied by the water supply device 20.

The salt water desalination apparatus 80, the high-temperature heat source pipe 90, and the cooling source pipe 92 move in the directions indicated by arrows in FIG.

FIG. 5 is a conceptual diagram illustrating a flow of a solar thermal system according to still another embodiment of the present invention. In FIG. 5, the solar thermal system comprises a solar pond 10, a first moisture provider 20, and a second It has a water supply device 120, a flash evaporation tank 210, a steam power generation device 220, and a cooling tank 230.

Salt water accumulates in the solar pond 10. The upper layer of the solar bond 10 is open, and the salt water in the upper layer is cooled by evaporative cooling or the like. The solar pound 10 may be plural.

Sea water is supplied to the first water supply device 20 from the sea 3 10. In the water supply device 20, the salt water absorbs water vapor evaporated from seawater. This dilutes the salt water. Seawater concentrated after the provision of water accumulates in salt fields 320. The seawater accumulated in the salt field 320 is further concentrated, whereby solid salts are precipitated in the salt field 320. Such solid salts may be used to form new solar ponds.

Into the flash evaporator tank 210, the hot salt water stored in the lower layer of the solar pond 10 is introduced. As a result, the salt water flash-evaporates in the flash evaporating tank 210 to release water vapor. This steam is introduced into the steam power generation device 220. The condensed water and steam after passing through the steam power generation device 220 are cooled in the cooling tank 230. With this cooling, the steam condenses into water. This cooling is performed by cooling water supplied to the cooling tank 230. As the cooling water, the salt water in the upper layer of the solar pond 10 is used. The condensed water is discharged to a fresh water tank 260 as fresh water. That is, the solar thermal system simultaneously performs power generation and freshwater production.

The exhaust device 240 exhausts the space in the cooling tank 230, whereby the non-condensable gas remaining in the cooling tank 230 is exhausted. The brine is concentrated with the flash evaporation of the brine. The flash After the steam evaporation, the salt water is returned to the lower layer of the solar bond 10. By controlling the salt concentration of the returned salt water, the salt concentration of the lower layer is maintained at a predetermined value. If it is necessary to dilute the brine after the flash evaporation, valve 128 opening is opened. The salt water is diluted by absorbing the water vapor evaporated from the sea water by the operation of the second water supply device 120 receiving the supply of the sea water from the sea 310. When the valve 456 is opened, the salt water is directly returned to the solar bond. Further, a concentrating device (not shown) may be provided in case the salt water needs to be concentrated.

FIG. 6 is a conceptual diagram illustrating a flow of a solar thermal system according to still another embodiment of the present invention. In FIG. 6, the solar thermal system includes a solar pond 10, a first moisture supply device 20, a second moisture supply device 120, a flash evaporation tank 210, and a steam power generator 2. 20 and a cooling tank 2 32. Further, a valve 456, a valve 128, and an exhaust device 240 are provided.

FIG. 7 is a conceptual diagram illustrating the inside of the cooling tank 232. The brine in the upper layer of the solar pound 10 is directly injected into the cooling tank 232. The altitudes of the salt water discharge part 610 and the salt water introduction part 620 are lower than the cooling tank 232. For this reason, the inside of the cooling tank 232 realizes a vacuum state of a tricelli. A shelf-shaped flow path 2 34 is provided in the cooling tank 2 32, and the salt water flows in a direction indicated by an arrow in the cooling tank 2 32. The salt water is directly absorbed by steam and discharged. The exhaust device 240 exhausts the space in the cooling tank 232.

FIG. 8 is a conceptual diagram illustrating a flow of a solar thermal system according to still another embodiment of the present invention. In FIG. 8, the solar thermal system The solar pump 10, the first moisture supply device 20, the second moisture supply device 120, the flash evaporation tank 210, the steam power generation device 220, and the cooling tank 2 32, a heat exchanger 250, and a concentrator 50. In addition, a valve 56, a valve 456, a valve 128, an exhaust system 240, and a freshwater tank 260 will be provided.

The heat exchanger 250 receives the supply of salt water in the upper layer of the solar pond 10 and uses this to cool the fresh water circulating between the heat exchanger 250 and the cooling tank 2332. I do. The fresh water cooled by passing through the heat exchanger 250 is directly injected into the cooling tank 232. The fresh water absorbs water vapor in the cooling bath 232. An amount of the fresh water corresponding to the injection amount is returned to the heat exchanger 250. Excess fresh water is discharged to a fresh water tank 260. That is, the solar thermal system simultaneously performs power generation and freshwater production. When the valve 56 is opened, the brine is further concentrated by the concentrator 50 and returned to the lower layer of the solar bond 10. When the valve 128 is opened, the salt water is diluted by the water supply device 120 and returned to the lower layer of the solar bond. When the valve 456 is opened, the salt water is returned to the lower layer of the solar bond 10 as it is. A controller (not shown) may be provided to control the concentration distribution of the salt water stored in the solar pond 10. In this case, the controller includes the valve 56, the valve 128, the valve 456, the first moisture supply device 20, the second moisture supply device 120, and the The operation of the concentrator 50 is controlled.

FIG. 9 is a conceptual diagram illustrating a flow in a method of forming a solar bond according to still another embodiment of the present invention. In FIG. 9, the salt water dissolving tank 330 is arranged to accumulate salt water in the solar pond 10. Be provided. Solid salt and a small amount of salt water saturated with the salt are accumulated in the salt water dissolving tank 330. The salt water in the saturated state is supplied to the water supply device 20.

From the sea 310, seawater is supplied to the water providing device 20. The value of the molar boiling point rise of the salt water in the saturated state is larger than the value of the molar boiling point rise of the seawater. Therefore, the water vapor evaporated from the seawater in the water supply device 20 is absorbed by the salt water. At this time, the volume of the salt water increases. A part of the salt water diluted to a predetermined concentration by the operation of the water supply device 20 is supplied to the solar bond 10, whereby the salt water having a predetermined concentration is accumulated. The remaining salt water that has become unsaturated due to the supply of water is returned to the dissolution tank 330. The solid salt is dissolved in the unsaturated salt water in the dissolving tank 330, and the saturated salt water is supplied again to the water supply device 20 at the outlet of the dissolving tank 330. It is. By repeating this, it is realized that the salt water having a predetermined concentration distribution is accumulated in the solar bond. The salt water is clean because non-volatile impurities contained in seawater do not enter the salt water. Thus, a method for forming a solar bond using inexpensive seawater as a water source is provided. Seawater concentrated by providing water may be drained to salt fields 320. The solid salts precipitated in the salt field 320 may be supplied to the dissolution tank 330. Further, the solid salts may be used to accumulate salt water in another solar pond.

FIG. 10 is a conceptual diagram illustrating the inside of a moisture providing device provided in a solar bond according to still another embodiment of the present invention. The water supply device 120 is provided with a closed flow path 44, a blowing means 470, 3 There are a plurality of shelves 450 falling down, and a plurality of shelves 450 flowing down water containing impurities.

The water containing the impurities is supplied from the upper part of each shelf 450, and the water containing the dull material flows down the shelf, and is discharged out of the system from the lower part.

The upper portion of each shelf 460 is supplied with the salt water below the solar ponds, and the salt water flows down the shelves and is returned from the lower portion to the solar ponds. The plurality of shelves 450 and the plurality of shelves 460 are alternately arranged in the closed flow path 450.

A circulating airflow indicated by a plurality of arrows in FIG. 10 is generated in the closed channel 440 by the blowing means 470. As the air stream passes through the shelf 450, the air stream is humidified by water vapor evaporated from the water containing the impurities. Next, when the air stream passes through the shelf 460, the salt water dehumidifies the air stream. In this process, the water vapor evaporated from the water containing the impurities is absorbed by the salt water. Thereby, the salt water is diluted. FIG. 11 is a conceptual diagram illustrating a solar thermal system according to still another embodiment of the present invention. In FIG. 11, the solar thermal system has a solar pond 10, a moisture providing device 20, a solar radiation concentrating device 900, and a reflecting mirror 910. The solar radiation concentrator 900 concentrates solar radiation towards the reflector 9110. The solar radiation reflected by the reflecting mirror 910 is applied to the solar bond 10. The arrows in Fig. 11 indicate the direction of solar radiation. This increases the energy density of the solar radiation applied to the solar pond 10. Thereby, high-temperature thermal energy is supplied.

FIG. 12 shows a solar thermal system according to still another embodiment of the present invention. It is a conceptual diagram explaining the flow of. In FIG. 12, the solar thermal system has a solar pond 10, a moisture providing device 20, a plurality of vapor-permeable water-repellent pipes 810, and a solar thermal power generation device 820.

The plurality of vapor-permeable water-repellent pipes 8 10 do not permeate water but transmit vapor. The plurality of vapor-permeable water-repellent pipes 810 are installed above a lower layer of salt water accumulated in the solar bond. A steam flow path is formed that connects the plurality of steam-permeable water-repellent tubes 8 10 in series. Steam circulates in the steam flow path. The pressure in the steam flow path may have a value close to the pressure of the salt water in the steam-permeable water-repellent pipe. In this case, a non-condensable gas may be contained in the vapor flow path. Instead, an exhaust device (not shown) for exhausting the non-condensable gas may be provided so that the non-condensable gas is not contained in the steam flow path. The upper surface of the vapor channel may be colored black to absorb solar radiation. The steam flow path supplies heat to the solar thermal power generator 820.

In the foregoing, the solar thermal system with solar bonds, the method of maintaining a solar pond, and the method of forming a solar pond according to the present invention have been described in detail. In addition, auxiliary means for suitably operating the solar heat system, the method for maintaining a solar bond, and the method for forming a solar bond according to the present invention, for example, a solar heat collecting means, a heat storage means, a vacuum system, a temperature sensor, a salt Concentration sensor, aeration device, filter, transparency sensor, heat pipe, windproof side wall, wave suppression means provided on the surface of salt water, container accommodating the water supply device, liquid supply means, flow rate adjustment means, and heat or heat The present invention may be implemented with an exchange means or the like.

SUMMARY OF THE INVENTION The invention disclosed herein is directed to a solar thermal system having a novel solar bond, a method for maintaining a solar pound, and Although the present invention provides a method for implementing the present invention, in view of the teachings disclosed in the above detailed description, the practice of the present invention is not limited to the above-described embodiment which has been made to explain the best mode of the present invention. However, the present invention may be embodied in other forms with various changes within the scope of the following claims, or additional forms added to describe the best embodiment among the above-described embodiments, It may be implemented without components. Industrial applicability

Because the present invention has been made as described above, a solar heat system having a new solar bond and a method for maintaining a solar bond using a water source containing water having impurities such as seawater are provided. The solar heat system may be used as a heat source for a solar system, a heat source for a solar thermal power generation system, a heat source for desalination of seawater, or a heat storage means for storing waste heat of the solar thermal power generation system.

Claims

The scope of the claims

1. A solar thermal system comprising: a solar pond that accumulates salt water heated by solar radiation; and a water supply device that causes the salt water to absorb water vapor evaporated from water containing impurities.

2. The solar thermal system according to claim 1, wherein the water supply device has an absorption heat pump that receives the supply of the salt water and the water containing the impurities.

3. The solar thermal system according to claim 1, further comprising a concentrating device for concentrating the salt water.

4. The solar thermal system according to claim 3, wherein the concentrating device is a distillation device.

5. A method for maintaining a solar bond, comprising: a step of accumulating salt water having a predetermined concentration distribution in a solar bond; and a step of absorbing water vapor evaporated from water having impurities into the salt water.

6. The method for maintaining a solar bond according to claim 5, further comprising a step of concentrating the salt water.

7. a step of dissolving a solid salt with unsaturated salt water, a step of supplying the salt water in which the solid salt is dissolved to a water supply device, and a step of removing water vapor evaporated from water having impurities in the water supply device. Absorbing the solid salt in the salt water in which the solid salt is dissolved; and refluxing a part of the salt water in which the water vapor evaporating from the water containing the impurities is absorbed into the solid salt, thereby returning the solid salt to the solid salt. Further comprising: dissolving the salt water; and sending the residual salt water that has absorbed water vapor evaporated from the water having impurities to a solar pond.