JP2012041849A - Concentration difference power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a closed cycle concentration difference power system which can achieve improvement of power generation efficiency by reducing a calorific value of a heat source required for generation of a solvent.SOLUTION: A closed cycle concentration difference power system which recycles a solvent and concentrated liquid obtained by leading a high concentration side solution passing though a permeator 10 to a concentration cycle 50 while generating power by converting into mechanical energy the osmotic pressure of a solvent penetrating a semipermeable membrane 11 in the permeator 10 and flowing therein, utilizes two solutions having different concentration, which are liquid mixtures formed by combining a solvent having smaller calorific value required for evaporation than water and a solute dissolved in the solvent.

Description

  The present invention relates to a concentration difference power generation system that generates power using two solutions having different concentrations, and more particularly to a concentration difference power generation system in a closed cycle.

In recent years, a concentration difference power generation apparatus has been proposed that uses two solutions having different concentrations, such as seawater and river water, and generates power using the osmotic pressure between the two liquids separated by a semipermeable membrane.
The osmotic pressure is a pressure acting from a solvent or a low concentration solution toward a high concentration solution. That is, a solution of a solute that does not pass through the semipermeable membrane is directed from a relatively low concentration solution to a relatively high concentration solution through the semipermeable membrane when separated by the semipermeable membrane at different concentrations. Since a solvent flow occurs, the solvent flow that occurs through the semipermeable membrane is called osmosis, and the pressure is called osmotic pressure. In addition, the semipermeable membrane mentioned above is a membrane which permeate | transmits only a solvent.

As such a concentration difference power generation device, two types of an open cycle and a closed cycle are known.
On the other hand, in the open cycle, two solutions are supplied to the permeation apparatus separated by the semipermeable membrane, thereby generating power using the permeation and osmotic pressure of the solvent passing through the semipermeable membrane. The solution after passing through the permeation device and the solvent after power generation are both treated as waste water. That is, in the case of an open cycle using seawater and river water, for example, seawater and fresh water introduced from the sea or river are returned to the sea or river as drainage after being used for concentration difference power generation.

  However, in the closed cycle, for example, by combining a concentration cycle such as a multiple effect method (MED) used for seawater desalination, the solution that has passed through the permeation device is concentrated to produce a solvent and a concentrated solution. Since the solvent and the concentrated liquid thus generated are returned to the permeation device and used for the concentration difference power generation, the concentration difference power generation is continued by circulating in the same closed loop system.

  As a technology related to the above-described concentration difference power generation device, a semipermeable membrane (see Patent Document 1) composed of a thin film layer (diffusion layer) of a non-porous material and one or more layers (porous layer) of a porous material, Known is an osmotic heat engine that converts osmotic pressure into electric power using a semipermeable membrane (see Patent Document 2), and a driving method of a prime mover using osmotic energy related to concentration difference power generation in a closed cycle (see Patent Document 3). It has been.

Special table 2004-50564 gazette Special table 2010-509540 Special table 2007-533884 gazette

By the way, the conventional concentration difference power generation apparatus uses river water and seawater as a general working fluid.
However, the concentration of seawater is about 3.5 wt%, and therefore it is difficult to obtain high osmotic pressure between river water / seawater. In addition, when seawater is used as the working fluid, there is a problem that the installation location suitable for the concentration difference power generation device is limited to the coast adjacent to the river. Furthermore, since river water and seawater are contaminated, it is difficult to maintain and manage the cleanliness of the semipermeable membrane used in the permeation device.

As a solution to the above-described problem, it is conceivable to employ a closed-cycle concentration difference power generation system. However, the closed cycle concentration difference power generation system has a problem that when seawater is used as a working fluid, the amount of heat of evaporation of water required for recirculation is large. That is, in a concentration cycle such as the multi-effect method (MED), a heat source with a large amount of heat is used as a heating source for precipitating salt (solute) such as sodium chloride from seawater (solution) to produce fresh water (solvent). Is required. For this reason, in a closed cycle concentration difference power generation system, in order to improve power generation efficiency, it is desired to generate a solvent with a heat source having a smaller amount of heat.
The present invention has been made to solve the above-described problems, and the object of the present invention is to provide a closed-cycle concentration difference power generation that can achieve an improvement in power generation efficiency by reducing the amount of heat of a heat source necessary for the generation of a solvent. To provide a system.

In order to solve the above problems, the present invention employs the following means.
The concentration difference power generation system according to the present invention uses two solutions having different concentrations, converts the osmotic pressure of a solvent flowing through the semipermeable membrane in the permeation device into mechanical energy, and generates power, and the permeation device. In a closed cycle concentration difference power generation system that circulates and reuses the solvent and concentrate obtained by guiding the high-concentration solution that has passed through the concentration section, the solution requires less heat to evaporate than water or water It is a liquid mixture composed of a combination of a solvent and a solute dissolved in the solvent.

  According to such a concentration difference power generation system, the two solutions having different concentrations are a liquid mixture composed of a combination of water or a solvent having a smaller amount of heat required for evaporation than water and a solute dissolved in the solvent. Therefore, it is possible to operate with a reduced amount of heat from the heat source required to evaporate the solvent during solution recycling. In the present invention, the two solutions having different concentrations include a pure solvent in which the solution on the low concentration side does not contain any solute.

In this case, suitable solvents include substances having a boiling point lower than that of water and a small latent heat of vaporization, such as ethylene oxide, ethanol, heptane, hydrofluoroether (HFE). However, there are some substances, such as isobutyl alcohol and phenol, whose boiling point or latent heat of vaporization is lower than water, but the amount of heat required for evaporation is smaller than that of water. Such solvents and solutes dissolved in these solvents Can be combined with.
As a combination of a solvent and a solute suitable for the above invention, the solvent is water, the solute is ammonium carbonate (NH ₄ CO ₃ ), the solvent is water, and the solute is ammonia (NH ₃ ).

  In the above invention, the osmotic device preferably includes a heating means and / or a heat retaining means for increasing the temperature of the solution, whereby the temperature of the solution flowing through the osmotic device is increased, whereby the osmotic pressure is increased. Get higher.

In the above invention, the semipermeable membrane module of the osmosis device is preferably placed vertically so that the flow direction of the solution is in the vertical direction, whereby the concentration polarization formed around the semipermeable membrane Can be prevented or suppressed.
When the semipermeable membrane module is installed vertically, concentration polarization can be prevented or suppressed by natural convection by heating the solution and raising the temperature.

  In the above invention, the permeation apparatus preferably includes an ultrasonic wave generating means for minutely vibrating the solution on the high concentration side, whereby concentration polarization can be prevented or suppressed.

In the above invention, the concentration part preferably adjusts the concentration by utilizing the temperature dependence of the solubility of the solution, thereby precipitating the solute by cooling the solution and heating the solute by heating. Can be dissolved in a solvent to obtain a high-concentration solution.
In this case, exhaust heat from a factory, power plant, etc. can be used for heating, and heat radiation using cold heat such as stored snow or liquefied natural gas, or natural heat radiation due to cold nighttime in the desert can be used for cooling.

  In the above invention, the concentrating unit preferably includes a regenerative heat exchanger that exchanges heat between the solution on the cooling side and the solution on the heating side, thereby improving the thermal efficiency.

  In the above invention, the concentrating unit preferably includes an ultrasonic atomizing means for precipitating the solute from the solution, thereby reducing energy required for separation for precipitating the solute from the solution.

According to the present invention described above, the two solutions having different concentrations used in the closed-cycle concentration difference power generation system are constituted by a combination of water or a solvent having a smaller heat flow required for evaporation than water and a solute dissolved in the solvent. Since the liquid mixture to be used is employed, it is possible to reduce the amount of heat of the heat source required for evaporating the solvent when the solution is recycled. As a result, in the concentration difference power generation system of the closed cycle, a remarkable effect of improving the power generation efficiency is obtained by reducing the amount of heat consumed by the heat source during operation.
In addition, if a concentration unit that adjusts the concentration using the temperature dependence of the solubility of the solution is adopted, the amount of heat required can be reduced compared to the evaporation method such as the multiple effect method, which also improves the power generation efficiency. Is possible.

BRIEF DESCRIPTION OF THE DRAWINGS It is a systematic diagram of the apparatus structure which shows one Embodiment about the concentration difference power generation system of the closed cycle which concerns on this invention. It is a figure which shows an example of the osmosis | permeation apparatus shown in FIG. 1, (a) is a principal part cross-sectional front view, (b) is a principal part cross-section enlarged view of the 1st modification which provided the heating / heat retention apparatus. It is a principal part cross-sectional front view which shows the 2nd modification made into vertical installation about the osmosis | permeation apparatus shown in FIG. It is a systematic diagram of the apparatus structure which shows a 1st modification about the concentration cycle shown in FIG. It is a systematic diagram of the apparatus structure which shows a 2nd modification about the concentration cycle shown in FIG. It is a systematic diagram of the apparatus structure which shows a 3rd modification about the concentration cycle shown in FIG. It is a systematic diagram of the apparatus structure which shows a 4th modification about the concentration cycle shown in FIG. It is a systematic diagram of the apparatus structure which shows a 5th modification about the concentration cycle shown in FIG. It is a systematic diagram of the apparatus structure which shows a 6th modification about the concentration cycle shown in FIG. It is a systematic diagram of the apparatus structure which shows a 7th modification about the concentration cycle shown in FIG. It is a systematic diagram of the apparatus structure which shows an 8th modification about the concentration cycle shown in FIG.

Hereinafter, an embodiment of a concentration difference power generation system according to the present invention will be described with reference to the drawings.
In the embodiment shown in FIG. 1, the illustrated concentration difference power generation system is a closed cycle system in which a tank switching type concentration difference power generation device 1 is combined with a concentration cycle 50 of a multiple effect method (MED) as a concentration unit. In the embodiment described below, the two solutions having different concentrations also include a pure solvent having a concentration of 0% in which the low concentration solution does not contain any solute.

The concentration difference power generation device 1 includes a permeation device 10, a low concentration solution system 20 that supplies a low concentration solution to the permeation device 10, a high concentration solution system 30 that supplies a high concentration solution to the permeation device 10, and a generator 2. And a turbine 3 to be driven.
In the osmosis device 10, a flow path for flowing a low concentration solution and a high concentration solution is formed inside the vessel after being separated into the semipermeable membrane 11, and the solvent on the low concentration solution side penetrates the semipermeable membrane 11 to increase the concentration. It flows into the solution side. For example, as shown in FIG. 2, the normal permeation apparatus 10 has a vessel 12 placed horizontally, and low-concentration solution and high-concentration solution outlets are provided at both left and right end portions in the axial direction.

2 is a semipermeable membrane module provided with a number of hollow fiber-like semipermeable membranes 11 horizontally disposed inside a vessel 12 having a substantially cylindrical shape.
A high-concentration solution inlet 13a and a low-concentration solution outlet 14b are provided at the left end of the vessel 12 in the drawing, and a high-concentration solution outlet 13b and a low-concentration solution inlet 14a are provided at the right-end of the drawing. In this case, the low concentration solution flows in the hollow fiber-shaped semipermeable membrane 11, and the high concentration solution flows outside the semipermeable membrane 11.
In addition, the code | symbol 12a in a figure is a wall surface member which comprises the vessel 12. FIG.

Accordingly, one high-concentration solution flows into the permeation device 10 from the high-concentration solution inlet 13a on the left side of the paper, and flows out from the high-concentration solution outlet 13b on the right side of the paper together with the solvent that has permeated from the low-concentration solution. The other low-concentration solution flows into the infiltration device 10 from the low-concentration solution inlet 14a on the right side of the paper, and the solvent that has permeated into the high-concentration solution side decreases and flows out of the low-concentration solution outlet 14b on the left side of the paper.
That is, by passing through the permeation device 10, the concentration decreases on the high concentration solution side due to the addition of the permeated solvent, and on the low concentration solution side, the concentration increases due to the decrease of the permeated solvent. When a pure solvent is used for the low-concentration solution, the concentration does not increase, but the permeate flow rate decreases and flows out.

The low-concentration solution system 20 supplies the low-concentration solution to the permeation device 10 and collects the low-concentration solution whose concentration has increased through the permeation device 10. The low-concentration solution tank 21 stores the low-concentration solution. For example, a low-concentration solution pump 23 driven by an electric motor 22 and a low-concentration solution channel 24 through which the low-concentration solution flows are provided.
In this case, the low-concentration solution channel 24 forms a closed circuit channel in which the low-concentration solution in the low-concentration solution tank 21 returns to the low-concentration solution tank 21 again via the low-concentration solution pump 23 and the permeation device 10. is doing.

Therefore, the low-concentration solution stored in the low-concentration solution tank 21 is supplied to the permeation device 10 by the operation of the low-concentration solution pump 23, and returned to the low-concentration solution tank 21 in a state where the concentration has increased.
However, since the solvent generated in the concentration cycle 50 described later is supplied to the low concentration solution tank 21, the concentration increased in the permeation apparatus 10 can be set to a desired value by adjusting the supply amount from the concentration cycle 50. Can be maintained.

The high-concentration solution system 30 supplies a high-concentration solution to the permeation device 10 and employs a tank switching type including two high-concentration solution tanks 31a and 31b. In this method, for example, a filling pump 33 driven by an electric motor 32 is driven, and two high concentration solution tanks are filled with a high concentration solution from a high concentration solution supply source 34.
When operating the concentration difference power generation device, for example, a high concentration solution is introduced from one of the high concentration solution tanks 31a and 31b by a high concentration solution pump 36 driven by an electric motor 35, and this high concentration solution is a high concentration solution. The solution is supplied to the permeation apparatus 10 through the solution flow path 37.

The high concentration solution supplied to the osmosis device 10 is supplied to the turbine 3 with an osmotic pressure and increased flow rate by merging with the solvent that has permeated from the low concentration solution side. That is, the main energy of the fluid supplied to the turbine 3 is due to the osmotic pressure, and this energy is converted into mechanical energy of shaft output by driving the turbine 3. It is converted into electric power by the driven generator 2.
The medium-concentration solution that has driven the turbine in this way is guided to a concentration cycle 50, which will be described later, as medium-concentration drainage in a state where the concentration has decreased due to the merging of the solvents.

The high-concentration solution tanks 31a and 31b described above are filled with a high-concentration solution from the high-concentration solution supply source 34 or supplied from the concentration cycle 50 described later to the tank 34 when the other of the supply side tanks is empty. By filling the concentrated liquid (high-concentration solution), it is possible to prepare for the next supply in a state adjusted to a desired concentration.
The high-concentration solution tanks 31a and 31b can be selectively switched by operating a three-way valve (not shown) or the like, and continuous operation is possible by using the two high-concentration solution tanks 31a and 31b alternately. become.

The concentrating cycle 50 is a concentrating unit having a concentrating device 51 adopting a multiple effect method (MED) as a main component, and using a thermal energy such as heating steam supplied from a heat source 52, a concentration difference power generation device. The medium concentration solution supplied from 1, that is, the medium concentration drainage is heated. This heating evaporates the solvent in the medium concentration drainage liquid, so that the medium concentration drainage liquid can be separated into the solvent and the concentrated liquid.
In the solvent and the concentrated solution thus generated, the solvent is supplied to the low concentration solution tank 21 of the low concentration solution system 20, and the concentrated solution is supplied to the high concentration solution tank 34 of the high concentration solution system 30.

As a result, a closed loop is formed in which the intermediate concentration drainage is reused and circulated, so that the operation of the concentration difference power generator 1 can be continued by supplying heat energy mainly from the heat source 52 to the concentration cycle 50. It becomes a closed cycle concentration difference power generation system.
For this reason, when river water and seawater are used as two solutions having different concentrations, if the river water and seawater are first introduced, the seawater is heated by the heat source 52 to evaporate the water of the solvent. A closed cycle system that continues differential power generation is formed.

As described above, two solutions having different concentrations are used to generate electricity by converting the osmotic pressure of the solvent flowing through the semipermeable membrane 11 in the osmosis device 10 into mechanical energy, and to generate the osmosis device 10. In the closed cycle concentration difference power generation system that circulates and reuses the solvent and concentrate obtained by guiding the medium concentration drainage that has passed to the concentration cycle 50, in this embodiment, the amount of heat required for evaporation is smaller than that of water or water. A liquid mixture composed of a combination of a solvent and a solute dissolved in the solvent is used as the solution.
In addition, the solvent whose calorie | heat amount required for evaporation is smaller than water is specifically a substance with a boiling point lower than water and a small latent heat of vaporization.

Suitable solvents in this case include low boiling point solvents such as ethylene oxide, methanol, ethanol, heptane, hydrofluoroether (HFE) and the like.
Ethylene oxide is a substance having a boiling point / 10.66 ° C. and a latent heat of vaporization / 581.38479 KJ / kg, both of which are significantly lower than the boiling point of water / 100 ° C. and the latent heat of vaporization / 22256.381798 KJ / kg. In addition, substances such as ethanol, heptane, and hydrofluoroether (HFE) have a lower boiling point than water and also have a low latent heat of vaporization.

An example of a solute (absorbent) suitable for combination with ethanol, which is a low-boiling solvent, is lithium bromide (LiBr), for example.
Other suitable solutes (absorbents) such as hydrofluoroether (HFE) and chlorofluorocarbon refrigerants (R22, R21, R30, R31), for example, tetraethylene glycol dimethyl ether, cyclohexanone, tributyl phosphate, acetophenone, isophorone, etc. There is.

As described above, when a low-concentration solution and a high-concentration solution using a low-boiling solvent are used in the concentration difference power generation system, an operation in which the amount of heat of the heat source 52 required to evaporate the solvent during the solution recirculation is reduced. It becomes possible. That is, when the high-concentration effluent after power generation by the turbine 3 is separated into the solvent and the concentrated liquid by the concentration system 50, the boiling point of the solvent is low and the latent heat of evaporation is small. This can be greatly reduced compared to when water is used.
As a result, the concentration difference power generation system of the present embodiment improves the power generation efficiency of the entire system by significantly reducing the amount of heat consumed by the heat source 52 during operation, particularly when using river water and seawater. To do.
In addition, some solvents that require less heat for evaporation than water include substances such as isobutyl alcohol and phenol that have either a boiling point or a latent heat of evaporation lower than that of water. Therefore, it is also possible to use a solution in which a solvent having a boiling point lower than that of water and / or a latent heat of evaporation lower than that of water and a solute dissolved in this solvent are combined.

In the concentration difference power generation device 1 described above, it is desirable to perform heating and heat retention in order to increase the temperature of the solution flowing through the permeation device 10 and obtain a high osmotic pressure.
This utilizes the characteristic that a larger osmotic pressure can be obtained as the temperature of the solution supplied to the permeation apparatus 10 is higher. For example, as shown in FIG. 2B, a wall surface member 12a constituting the vessel 12 is used. The outer periphery is covered with a heat insulating material 15 for heat insulation, and a heater 16 is installed inside the heat insulating material 15 for heating.

That is, in order to increase the temperature of the low-concentration solution and the high-concentration solution flowing through the permeation apparatus 10, it is desirable that the permeation apparatus 10 includes the heater 16 of the heating means and / or the heat insulating material 15 of the heat retention means. When the osmotic pressure increases in this way, the amount of power generated by driving the turbine 3 and the generator 2 increases, so that the power generation efficiency of the concentration difference power generation apparatus 1 and the concentration difference power generation system as a whole improves.
Further, since the temperature of the solution flowing through the permeation device 10 described above only needs to be high, not only the configuration in which the permeation device 10 is directly heated and kept warm, but also, for example, a heater or the like at an appropriate place in the low concentration solution system 20 and the high concentration solution system 30 A heating means may be provided to raise the solution temperature, and the permeation device 10 may simply be kept warm.

In the semipermeable membrane module of the osmosis device 10 described above, concentration polarization that hinders osmotic pressure occurs around the semipermeable membrane 11 in the horizontal direction. This concentration polarization is a concentration difference that occurs in the vicinity of the high-concentration solution side of the semipermeable membrane 11, so that the flow directions of the low-concentration solution and the high-concentration solution are vertical as shown in FIG. If the semipermeable membrane module of the permeation device 10 is used in a vertical position, concentration polarization can be prevented or suppressed by the action of gravity.
In order to prevent or suppress such concentration polarization, the semipermeable membrane module may be placed vertically, and the temperature of the semipermeable membrane module may be increased by heating the solution described above. Prevents or suppresses concentration polarization.

Further, in order to prevent or suppress the above-described concentration polarization, it is also effective to provide an ultrasonic wave generating means (not shown) that causes the high concentration side solution to vibrate in the permeation apparatus 10. This ultrasonic wave generating means is an ultrasonic wave generating device installed at an appropriate position of a high concentration solution system 30 for supplying a high concentration solution to the permeation device 10, and the high concentration solution is vibrated with ultrasonic waves to prevent concentration polarization. Or it can be suppressed.
When concentration polarization is prevented or suppressed in this way, a high osmotic pressure can be obtained in the osmosis device 10, so that the amount of power generated by driving the turbine 3 and the generator 2 is increased, and the concentration difference power generation device 1 and the concentration are increased. The power generation efficiency of the entire differential power generation system is improved.

  Subsequently, instead of the concentration cycle 50 described above, a concentration unit that adjusts the concentration using the temperature dependence of the solubility of the solution may be employed. That is, since the solubility of the solute varies depending on the temperature, if a substance having this large change is used as the solute, the solute can be easily dissolved and precipitated according to the temperature change of the solution. In other words, the solute is precipitated by cooling the solution, and the solute can be dissolved in the solvent by heating to obtain a highly concentrated solution. In this case, the temperature difference can be relatively small.

A concentration cycle 50A shown in FIG. 4 is a system diagram showing a first modification of the concentration cycle 50 shown in FIG. In this case, the solute is solid.
The concentration cycle 50A is a concentration unit that adjusts the concentration by utilizing the temperature dependence of the solubility of the solution, and uses a regenerative heat exchanger 53 instead of the heat source 52 described above. The regenerative heat exchanger 53 is a device that performs heat exchange between a relatively high temperature medium concentration drainage liquid and a relatively low temperature precipitation liquid. In this case, the precipitation solution is in a state where a solid solute is precipitated in the solvent.

The high-temperature medium-concentration drainage liquid is supplied to the regenerative heat exchanger 53 via an intermediate tank 54 and a drainage pump 55 provided as necessary.
The low temperature precipitation liquid is supplied to the regenerative heat exchanger 53 via a precipitation tank 57 and a precipitation pump 58 provided as necessary.
In the regenerative heat exchanger 53, the high-temperature medium-concentration effluent is cooled to a low-temperature precipitation solution, and the temperature drops. That is, as indicated by an arrow H in the figure, the heat held by the medium concentration drainage moves to the low temperature precipitation solution side. For this reason, the solute dissolved in the medium concentration drainage is deposited as a solid in the precipitation device 56. As a result, a solvent containing a solute precipitate (solid) is accumulated in the precipitation device 56, and is separated into a pure solvent and a solvent precipitation solution containing a solute precipitate by filtration.

One solvent is supplied to the low-concentration solution tank 21 of the concentration difference power generator 1 described above by a pump (not shown) or the like. Since the solvent before being supplied to the low concentration solution tank 21 is stored, an intermediate storage tank (not shown) for the solvent may be installed as necessary.
The other precipitation liquid is supplied to the regenerative heat exchanger 53 directly from the precipitation device 56 or via the precipitation tank 58. Since this precipitation liquid is heated by heat exchange with the medium concentration waste liquid and the temperature rises, the solute precipitated in the solvent dissolves to become a high concentration solution (concentrated liquid). The high concentration solution is supplied to the above-described high concentration solution tank 34 by a pump or the like (not shown). In order to store the high-concentration solution before being supplied to the high-concentration solution tank 34, an intermediate storage tank (not shown) for the solvent may be installed as necessary.

In this way, since the medium concentration drainage liquid can be separated into the solvent and the high concentration solution using the regenerative heat exchanger 53, the heat efficiency is improved by eliminating the heat source 52. That is, by improving the thermal efficiency of the concentrator 50A, the power generation efficiency of the entire concentration difference power generation system is improved.
In addition, such a regenerative heat exchanger 53 can be appropriately combined with the concentrating device 51 and the heat source 52 according to the configuration of the concentration difference power generation system and various conditions such as the solution to be used. . Also in this case, since the heat energy of the heat source 52 can be reduced, the power generation efficiency of the entire concentration difference power generation system is improved by improving the thermal efficiency of the concentrator 50A.

The concentration cycle 50B shown in FIG. 5 is a system diagram showing a second modification of the concentration cycle 50 shown in FIG. In addition, the same code | symbol is attached | subjected to the part similar to the 1st modification mentioned above, and the detailed description is abbreviate | omitted.
In the concentration cycle 50B, an ultrasonic atomizing device 59 is provided as ultrasonic atomizing means for depositing a solute from the solution. The ultrasonic atomizer 59 atomizes the solvent with ultrasonic waves to promote solute precipitation. In the configuration example shown in the figure, since the ultrasonic atomizer 59 is installed in the precipitation liquid storage part of the precipitation device 56, it is possible to reduce the thermal energy required for separation for precipitating the solute from the solution.

A concentration cycle 50C shown in FIG. 6 is a system diagram showing a third modification of the concentration cycle 50 shown in FIG. In addition, the same code | symbol is attached | subjected to the part similar to each modification mentioned above, and the detailed description is abbreviate | omitted.
The concentration cycle 50 </ b> C is a concentration unit that cools the precipitation device 56 by natural heat radiation to precipitate a solute and heats the precipitation tank 57 by exhaust heat to perform melting. In this case, the regenerative heat exchanger 56 is not necessarily required, and may be provided as appropriate according to various conditions.

  The natural heat dissipation in this case includes, for example, cooling of a natural phenomenon at night in a desert, and the exhaust heat for heating includes, for example, exhaust heat from a boiler used in a power plant or factory. In addition, when using the coldness of the desert as natural heat dissipation, precipitation by natural heat dissipation may be performed at night, and melting using factory waste heat may be performed during the daytime.

The concentration cycle 50D shown in FIG. 7 is a system diagram showing a fourth modification of the concentration cycle 50 shown in FIG. In addition, the same code | symbol is attached | subjected to the part similar to each modification mentioned above, and the detailed description is abbreviate | omitted.
The concentration cycle 50D is a concentration unit that cools the precipitation device 56 by heat radiation using cold heat to precipitate the solute, and heats the precipitation tank 57 by exhaust heat to perform melting. In this case, the regenerative heat exchanger 56 is not necessarily required, and may be provided as appropriate according to various conditions.

  The heat release in this case uses, for example, the cold heat stored in snow, liquefied natural gas, etc. stored during the snowfall season. In addition, about the waste heat for a heating, it is the same as that of the 3rd modification mentioned above. Therefore, the high concentration waste liquid radiates heat by cooling the precipitation device 56 with cold heat such as snow or natural gas, and the precipitation tank may be heated using the exhaust heat such as factory waste heat for melting.

The concentration cycle 50E shown in FIG. 8 is a system diagram showing a fifth modification of the concentration cycle 50 shown in FIG. 1, and uses a gas such as NH ₃ CO ₂ as a solute. In addition, the same code | symbol is attached | subjected to the part similar to each modification mentioned above, and the detailed description is abbreviate | omitted.
The concentration cycle 50E is a concentration unit that separates a medium concentration drainage (medium concentration solution) into a solute gas and a solvent or a dilute solution using the regenerative heat exchanger 53A. That is, in the regenerative heat exchanger 53A, heat exchange is performed between the medium concentration waste liquid and the solute gas and the dilute solution (or solvent), and the medium concentration waste liquid side is heated to precipitate the solute gas. Dilute solution remains.

Furthermore, in the regenerative heat exchanger 53A, the dilute solution (or solvent) is cooled by heat exchange with the medium concentration drainage, so that the solute gas is absorbed into the dilute solution and becomes a high concentration solution (concentrated solution). That is, in the regenerative heat exchanger 53A used in this modification, as indicated by an arrow H in the figure, the heat of the solute gas and the dilute solution (or solvent) moves to the low-temperature medium concentration drainage side.
The solvent or dilute solution thus obtained is supplied to the permeation device 10 via a low concentration solution tank 21 (not shown), and the high concentration solution is supplied to the permeation device via high concentration solution tanks 31a and 31b (not shown). 10 is supplied.

Further, in the fifth modified example of FIG. 8, the solution is ammonium carbonate (NH ₄ CO ₃ ). However, as in the sixth modified example shown in FIG. 9, for example, a concentration cycle 50F using ammonia water instead of ammonium carbonate. Is also possible.
In the concentration cycle 50F shown in FIG. 9, medium concentration ammonia water becomes medium concentration drainage liquid, and is supplied to the regenerative heat exchanger 53A described above via the medium concentration ammonia water tank 54A.
In the regenerative heat exchanger 53A, heat exchange is performed between medium concentration ammonia water, ammonia gas (solute gas), and dilute concentration ammonia water (or solvent water), and the medium concentration ammonia water side is heated to convert ammonia gas. Since it precipitates, the solvent or dilute aqueous ammonia remains.

Further, in the regenerative heat exchanger 53A in this case, since the rare ammonia water (or solvent) side is cooled by heat exchange with the medium ammonia water, the ammonia gas is absorbed by the rare ammonia water and the high ammonia water is absorbed. (Concentrated liquid). That is, also in the regenerative heat exchanger 53A used in this modification, as indicated by an arrow H in the figure, the heat of ammonia gas and dilute ammonia water (or solvent) moves to the low-temperature medium-concentration ammonia water side.
The solvent or dilute aqueous ammonia thus obtained is supplied to the permeation device 10 through a low concentration solution tank 21 (not shown), and the high concentration ammonia water is supplied through high concentration solution tanks 31a and 31b (not shown). And supplied to the permeation apparatus 10.

The concentration cycle 50G shown in FIG. 10 is a system diagram showing a seventh modification of the concentration cycle 50 shown in FIG. 1, and uses a gas such as NH ₃ CO ₂ as a solute. In addition, the same code | symbol is attached | subjected to the part similar to each modification mentioned above, and the detailed description is abbreviate | omitted.
In this modified example, the regenerative heat exchanger is not used, and the medium concentration solution in the intermediate tank 54 is heated by exhaust heat such as factory exhaust heat to precipitate the solute gas. As a result, the medium concentration solution is separated into a solute gas and a solvent or a dilute solution. The solvent or dilute solution thus obtained is supplied to the permeation apparatus 10 via a low concentration solution tank 21 (not shown).

On the other hand, the solute gas and the dilute solution (or solvent) are introduced into the concentration tank 59, where they are cooled by natural heat dissipation or heat dissipation. As a result, the solute gas is absorbed by the dilute solution (or solvent) to become a high concentration solution (concentrated solution), and is supplied to the permeation apparatus 10 via high concentration solution tanks 31a and 31b (not shown).
In this case, the natural heat radiation includes cooling in the desert at night, and the heat radiation includes cold heat such as stored snow and liquefied natural gas. In the illustrated configuration example, the regenerative heat exchanger is not used, but may be appropriately combined depending on various conditions.

Further, in the seventh modified example of FIG. 10, the solution is ammonium carbonate, but, for example, as in the eighth modified example shown in FIG. 11, a concentration cycle 50H using ammonia water instead of ammonium carbonate is also possible.
Also in this case, the regenerative heat exchanger is not used, and the medium concentration ammonia water in the intermediate tank 54A is heated by exhaust heat such as factory exhaust heat to deposit ammonia gas. As a result, the medium concentration ammonia water is separated into ammonia gas and a solvent or dilute concentration ammonia water. The solvent or dilute concentration aqueous ammonia thus obtained is supplied to the permeation apparatus 10 via a low concentration solution tank 21 (not shown).

On the other hand, ammonia gas and dilute aqueous ammonia (or solvent) are introduced into the concentration tank 59, where they are cooled by natural heat dissipation or heat dissipation. As a result, the ammonia gas is absorbed by dilute aqueous ammonia (or solvent) to become high-concentration aqueous ammonia (concentrated liquid), and is supplied to the permeation apparatus 10 via high-concentration solution tanks 31a and 31b (not shown).
In this case, the natural heat radiation includes cooling in the desert at night, and the heat radiation includes cold heat such as stored snow and liquefied natural gas.
In the illustrated configuration example, the regenerative heat exchanger is not used, but may be appropriately combined according to various conditions as in the above-described sixth modification.

  As described above, according to the present embodiment and the modification thereof described above, the two solutions having different concentrations are constituted by a combination of water or a solvent having a smaller amount of heat required for evaporation than water and a solute dissolved in the solvent. Therefore, an operation can be performed in which the amount of heat of the heat source required for evaporating the solvent in the concentrating unit when the solution is recycled is reduced. Therefore, the above-described closed cycle concentration difference power generation system has improved power generation efficiency by reducing the amount of heat consumed by the heat source during operation.

Furthermore, if the concentration unit of each modified example that adjusts the concentration by utilizing the temperature dependence of the solubility of the solution is adopted, the required amount of heat is reduced compared to a concentration unit that employs an evaporation method such as a multi-effect method. This can also improve the power generation efficiency.
In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary, it can change suitably.

DESCRIPTION OF SYMBOLS 1 Concentration difference power generator 2 Generator 3 Turbine 10 Osmosis device 11 Semipermeable membrane 12 Vessel 15 Insulation material 16 Heater 20 Low concentration solution system 30 High concentration solution system 50, 50A-50H Concentration cycle (concentration part)
51 Concentrator (MED)
52 Heat source 53 Regenerative heat exchanger 56 Deposition equipment

Claims (9)

Two solutions with different concentrations are used to generate electricity by converting the osmotic pressure of the solvent that permeates the semipermeable membrane in the permeation device into mechanical energy and concentrates the solution on the high concentration side that has passed through the permeation device. In the closed cycle concentration difference power generation system that circulates and reuses the solvent and concentrate obtained by guiding to the section,
The concentration difference power generation system according to claim 1, wherein the solution is a liquid mixture composed of water or a solvent having a smaller amount of heat required for evaporation than water and a solute dissolved in the solvent. The concentration difference power generation system according to claim 1, wherein the solvent is water and the solute is ammonium carbonate (NH ₄ CO ₃ ). The concentration difference power generation system according to claim 1, wherein the solvent is water and the solute is ammonia (NH ₃ ).   The concentration difference power generation system according to any one of claims 1 to 3, wherein the permeation apparatus includes a heating unit and / or a heat retaining unit for increasing the temperature of the solution.   The concentration difference power generation system according to any one of claims 1 to 4, wherein the semipermeable membrane module of the permeation apparatus is vertically placed so that the flow direction of the solution is in the vertical direction.   6. The concentration difference power generation system according to any one of claims 1 to 5, wherein the permeation device includes an ultrasonic wave generation unit that minutely vibrates the solution on the high concentration side.   The concentration difference power generation system according to claim 1, wherein the concentration unit adjusts the concentration by utilizing temperature dependency of solubility of the solution.   The concentration difference power generation system according to claim 7, wherein the concentration unit includes a regenerative heat exchanger that exchanges heat between the solution on the cooling side and the solution on the heating side. The concentration difference power generation system according to claim 6 or 7, wherein the concentration unit includes an ultrasonic atomizing unit that precipitates the solute from the solution.

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