JP2016019944A - Clear water and electrical power supplying system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for readily and efficiently supplying clear water and electrical power at low cost in a region where both clear water infrastructure and electrical power infrastructure are not developed.SOLUTION: The system includes a forward osmosis water purification unit and a fuel cell unit to supply clear water and electrical power. In the system, the forward osmosis water purification unit and the fuel cell unit exchange heat between them.SELECTED DRAWING: None

Description

  The present invention relates to a system and method for supplying water and power. More specifically, the present invention relates to a system and method for supplying purified water and power easily, efficiently and inexpensively in remote areas, undeveloped land, emerging countries, etc. where basic infrastructure such as water purification and power generation facilities are not established.

Water and electricity are important for people to live a healthy and cultural life. Especially in the medical field, water is indispensable for preparation of pharmaceuticals, ensuring cleanliness, etc .; electric power is indispensable as lighting, power source for medical devices, etc.
In areas where basic facilities for living are not available, water is produced, for example, by desalination of seawater using a reverse osmosis membrane; electricity is produced, for example, by diesel power generation. Here, in the production of purified water using a reverse osmosis membrane, in addition to the drive power of the water pump, a large amount of power is required to create a pressure difference that is the drive source of reverse osmosis, so the cost of water purification is never low. Not something. In addition, diesel power generation is inefficient and has a large impact on the global environment in that it uses fossil fuel.

  As a method for producing purified water, forward osmosis technology is known in addition to the above-described method using a reverse osmosis membrane (Patent Documents 1, 2, etc.). The forward osmosis technology is a method in which the raw water to be purified is brought into contact with a draw solution containing a high concentration of solute separable from water through a semipermeable membrane, and only the water in the raw water is extracted into the draw solution. It is a technique for obtaining purified water by removing solutes from a draw solution. In the water purification system using the forward osmosis technology, the extraction of water from the raw water into the draw solution is driven by the osmotic pressure difference, so that no electric power is required to create an artificial pressure difference. However, such water purification technology has little merit in areas with good infrastructure (developed countries, urban areas, etc.).

On the other hand, a fuel cell is known as a method for producing electric power (for example, Patent Documents 3 and 4). A fuel cell is a technique for extracting electric power generated by a chemical reaction between hydrogen and oxygen. The hydrogen can be obtained by reforming a raw material gas (for example, liquefied petroleum gas, natural gas, etc.), and the oxygen can be obtained from the air.
As the fuel cell, for example, a polymer electrolyte fuel cell, a solid oxide fuel cell, and the like are known. When a polymer electrolyte fuel cell is used as the fuel cell, it is necessary to maintain a driving temperature of about 70 to 100 ° C. Here, the fuel cell reaction is an exothermic reaction, and heat is also generated by various resistance components in the battery. Therefore, cooling is required when driving the polymer electrolyte fuel cell. On the other hand, in the case of a solid oxide fuel cell, cooling is unnecessary because it is premised on high temperature operation of about 700 to 1,000 ° C. However, if the heat generated by driving the battery is not taken out and used, the diesel power generation The merit in terms of efficiency when compared to is diminished.

As a cooling medium for cooling the polymer electrolyte fuel cell and a heat medium for recovering heat from the solid oxide fuel cell, water is usually used, and the generated heat is recovered as hot water. The cooling water used here needs to be purified water from the request | requirement which suppresses generation | occurrence | production of fouling in piping as much as possible.
In the present specification, the term “cooling” is used as a concept including heat recovery from a solid oxide fuel cell.
The fuel cell can generate power that is environmentally clean. However, since the power generation capacity is relatively small, it is insufficient as a basic power generation facility in urban areas. For example, fuel cells in Japan are only used on a small scale, such as power sources for driving electric vehicles and auxiliary power sources for household use. On the other hand, in a region where power infrastructure is not established (for example, emerging countries), even a fuel cell has a capacity that is sufficiently worth considering as a main power source in a medical facility, for example, in addition to being used as a home power source. However, it is not easy in emerging countries to obtain and supply the cooling water necessary for driving the fuel cell at low cost.

  Furthermore, the water purification infrastructure and the power infrastructure have been developed and supplied by different operators. There is no active cooperative system between the two operators, and therefore, the consciousness of supplying purified water and electric power as a set in the prior art is scarce.

Special table 2014-512951 gazette International Publication No. 2014/078415 Pamphlet JP 2013-101822 A JP 2014-86130 A

The present invention has been made in order to overcome the above-described present situation.
An object of the present invention is to provide a system and method for supplying purified water and electric power easily, efficiently and inexpensively in an area where both the purified water infrastructure and the electric power infrastructure are not provided.

The present inventors proceeded with studies to achieve the above object.
The inventors have
A survey and research was conducted focusing on the fact that part of the purified water obtained by the forward osmosis system can be used as purified water for cooling the fuel cell; and that heat exchange is possible between the forward osmosis system and the fuel cell. However, by organically coupling the forward osmosis system and the fuel cell, it has been found that it becomes possible to simultaneously supply purified water and electric power as an independent system separated from other infrastructure facilities, and the present invention has been achieved. It is also an advantageous condition for implementing the present invention that the water purification system by forward osmosis can be driven with relatively small electric power.

The present invention is embodied in the following aspects.
[1]
A system for supplying purified water and power having a forward osmosis water purification unit and a fuel cell unit,
The system according to claim 1, wherein heat exchange is performed between the forward osmosis water purification unit and the fuel cell unit.

[2]
The heat exchange is
Using purified water supplied from the forward osmosis water purification unit as cooling water for the fuel cell unit, and using purified water after cooling the fuel cell unit as a heat source for the forward osmosis water purification unit, The system according to [1].

[3]
The heat exchange is
Using a heat medium that circulates between the forward osmosis water purification unit and the fuel cell unit,
The system according to [1], which is performed by using heat generated from the fuel cell unit as a heat source of the forward osmosis water purification unit.

[4]
The system according to any one of [1] to [3], wherein the drive power of the forward osmosis water purification unit is power supplied from the fuel cell unit.

[5]
The forward osmosis water purification unit is
The osmosis extraction part adjacent to the supply side area through which the raw water to be circulated flows and the draw-out area through which the draw solution circulates through the semipermeable membrane, and the drawn solution after the extraction are separated and recovered. The system according to [1], including a separation and recovery unit.

[6]
The solute of the draw solution in the forward osmosis water purification unit is selected from a solute consisting of a diol (co) polymer and a solute consisting of a combination of a volatile cation source and a volatile anion source, [1] to [5] The system according to any one of the above.

[7]
The fuel cell unit is
[1] The system according to [1], including a reformer that reforms a raw material gas to generate hydrogen, and a fuel cell that generates power by a reaction between hydrogen supplied from the reformer and air.

[8]
The system according to [7], wherein the fuel cell is a polymer electrolyte fuel cell or a solid oxide fuel cell.

[9]
A method for supplying purified water and power using a system having a forward osmosis water purification unit and a fuel cell unit,
The method according to claim 1, wherein heat exchange is performed between the forward osmosis water purification unit and the fuel cell unit.

By using a part of the purified water produced by the forward osmosis system as the purified water for heat recovery of the fuel cell, the fuel cell can be efficiently operated even in an area without a water purification infrastructure. Further, by using the heat recovered from the fuel cell in the form of hot water as a heat source for the forward osmosis system, the operating cost of the entire system is reduced in a superimposed manner.
Furthermore, since the forward osmosis system can be driven with relatively small electric power, even if a part of the electric power generated by the fuel cell is diverted to the forward osmosis system, most of the obtained electric power is, for example, in emerging countries. It can be used as a household power source, a main power source for medical equipment, and the like.
And the system and method of this invention can operate | move as an independent system separated from other infrastructure facilities, and can supply purified water and electric power. Therefore, the system and method are suitable for water supply / power supply in remote areas, undeveloped land, emerging countries, etc. where basic infrastructure such as water purification and power generation facilities is not established.

Schematic for demonstrating the operation principle about one form of the system in this Embodiment. Schematic for demonstrating the principle of operation about another form of the system in this Embodiment. Schematic which shows the one aspect | mode of the system in this Embodiment. Schematic which shows the one aspect | mode of the system in another form of this Embodiment.

The system of the present invention
A system for supplying purified water and power having a forward osmosis water purification unit and a fuel cell unit,
Heat exchange is performed between the forward osmosis water purification unit and the fuel cell unit.

<Normal osmosis water purification unit>
The forward osmosis water purification unit in the present embodiment is a forward osmosis extraction unit in which a supply side region through which raw water to be circulated circulates and a draw-out side region through which a draw solution circulates are interposed via a semipermeable membrane, and after extraction A separation / recovery unit for removing solute from the draw solution and separating and recovering purified water.
Examples of the raw water to be purified include seawater, brackish water, drainage, contaminated water, low-quality tap water, and other aqueous solutions.
Hereinafter, the draw solution, semipermeable membrane, and separation / recovery unit related to the forward osmosis water purification unit will be described.

[Draw solution]
The draw solution used in the present embodiment contains a solute separable from water at a high concentration. The solute needs to be able to dissolve in water at a high concentration and be easily separated from water after extracting the water from the raw water. The term “separation” as used herein refers to any of separation by separating from the solution as a gas, separation by multilayering of the solution, separation by precipitation as a solid, separation by restraint by formation of a chemical bond, etc. It may be.
Therefore, the solute used in the present embodiment includes a solute having a large temperature dependency of solubility, a solute that can be constrained and released by the temperature change, a solute that is gasified at a low temperature, and a difference in solubility due to pH change. Examples of solutes having a large size, solutes that can be separated by application of magnetism, and the like.
In the present embodiment, it is possible to use the heat recovered from the fuel cell; and the temperature dependency of the solubility is large from the viewpoint of handling property in the solute recovery scene by the separation recovery unit described later. It is preferable to use a solute, a solute that gasifies at a low temperature, or a solute that can be converted into a restraint / free state by a change in temperature. Specific examples of such solutes include the following solutes.

  Examples of the solute having a large temperature dependency of solubility include a diol (co) polymer. Examples of the diol (co) polymer include 1,2-ethanediol (ethylene glycol), 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexane Diol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-heptanediol, 1,7-heptanediol, 3,4-heptanediol, diethylene glycol, and neopentyl glycol Homopolymers of diols selected from the group consisting of, and these diols It can be exemplified a copolymer of two or more of. Among these, a homopolymer of propylene glycol or a copolymer of ethylene glycol and propylene glycol is preferable. In the latter case, the form of copolymerization may be random copolymerization, block copolymerization, graft copolymerization, or a combination thereof.

  For the diol (co) polymer, the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography is preferably 500 to 10,000, more preferably 500 to 5,000, and particularly 500 to 3 ,. 000 is preferred. Since the diol (co) polymer having such a molecular weight has high solubility in water, it is preferable in that a draw solution showing a high osmotic pressure that can be suitably used in the present embodiment can be easily prepared.

  These diol (co) polymers have high water solubility at low temperatures, but the water solubility is significantly reduced at high temperatures and separate from water to form oil droplets. Therefore, by heating the draw solution after extracting water from the raw water, it becomes possible to separate the diol (co) polymer and easily recover only purified water.

Examples of the solute that gasifies at a low temperature include a solute composed of a combination of a volatile cation source and a volatile anion source. Examples of the volatile cation source include NH ₃ , R—NH ₂ , R ₃ —N (where R is an alkyl group having 1 to 10 carbon atoms) and the like;
Examples of the volatile anion source include CO ₂ and H ₂ S.
Each can be mentioned.
These volatile solute combinations form a salt consisting of a cation-anion pair at a low temperature and dissolve in water at a high concentration, but return to the original volatile gas at a high temperature. Therefore, by heating the draw solution after extracting the water from the raw water, it becomes possible to separate these volatile gases and easily recover only the purified water.

Examples of solutes whose restraint / free state can be mutually converted by temperature change include diene compounds. The diene compound is dissolved in the solvent in a free state at a high temperature, but forms a new bond by a Diels-Alder reaction with a dienophile (parent diene body) at a low temperature. Therefore, the diene compound can be removed from the draw solution by bringing the dienophile into contact with the diene compound in a state of being supported on a suitable carrier. Further, this reaction is reversible, and the draw solution can be easily regenerated because the diene compound is liberated by raising the temperature of the system.
Examples of such diene compounds include cyclopentadiene and the like;
Examples of the dienophile include maleic acid;
Examples of the carrier include silica.

The draw solution used in the present embodiment is a solution containing a high concentration of solute at a low temperature, and the solute is removed from the solution at a high temperature. It is more advantageous than being removed. The reason for this is that the solubility of such a solute changes due to the phase transition, so that the separation point of the solute appears clearly, so that the separation of the solute from the draw solution can be performed easily, reliably and completely. For these reasons, as the solute of the draw solution used in the present embodiment, among the above, the solubility has a large temperature dependency, but the solute has a higher solubility at a low temperature, or gasifies at a low temperature. Preferably it is a solute.
In addition to the solute as described above, the draw solution used in the present embodiment may further contain other components such as a pH adjusting agent, a viscosity adjusting agent, a pigment, a fungicide, and a rust inhibitor. . However, in order to improve the purity of the purified water obtained as much as possible, it is preferable not to contain these other components.

The osmotic pressure of the draw solution used in the present embodiment is preferably 10 kgf / cm ² or more at the extraction temperature (for example, 25 ° C.) from the viewpoint of increasing the water extraction capability and the extraction speed. On the other hand, in order to suppress the osmotic pressure within a range that the semipermeable membrane can withstand, it is preferable that the extraction temperature is 200 kgf / cm ² or less. Range of osmolality draw solution, more preferably, to 30~150kgf / cm ^2, it is preferable that the particular 50~100kgf / cm ^2.
The solute concentration for indicating such osmotic pressure can be easily obtained by calculation using the van't Hoff equation when the solute is composed of, for example, a combination of a volatile cation source and a volatile anion source. . When the solute is a diol (co) polymer, the osmotic pressure of the draw solution can take a wide range of values depending on the structure and molecular weight of the polymer. However, the appropriate solute concentration in this case can be readily determined by a few preliminary experiments by those skilled in the art.

[Semipermeable membrane]
The semipermeable membrane used in the present embodiment can be a membrane made of, for example, cellulose acetate, aromatic polyamide, aromatic sulfone, polybenzimidazole, graphene, or the like. These semipermeable membranes may be modified with hydrophilic ions (for example, sulfonate ions).
The shape of the semipermeable membrane may be an appropriate shape such as a flat membrane, a spiral flat membrane, or a hollow fiber membrane.
The semipermeable membrane is preferably used in a state of being accommodated in an appropriate module. Examples of the module used here include a cylindrical module, a skein module, and a stack module.

[Separation and recovery unit]
The separation and recovery unit in the present embodiment has a function of separating purified water and solute from the extracted draw solution.
The water-rich draw solution after extracting water from the supplied raw water is supplied to the separation and recovery unit in a heated state as will be described later. Since the water solubility of the solute in the draw solution is remarkably reduced by increasing the temperature, the solute in the feed solution is separated from the solution in the separation and recovery unit. Here, when the solute is, for example, a diol (co) polymer, the supply liquid is dispersed with a water-rich portion substantially containing no solute and a solute-rich portion containing the solute at a high concentration. It will be in the state. In the case where the solute is composed of, for example, a volatile cation source and a volatile anion source, the solute is vaporized by the temperature rise and detached from the solution.
Therefore, by separating the solute-rich part from the water-rich part (after aggregating it if necessary) by appropriate separation and recovery means, the solute and (crude) purified water can be recovered respectively. it can.

Examples of the separation / recovery means in the separation / recovery unit include a separation tank, a coalescer, a centrifuge, and a nanofilter.
The separation tank has a function of separating purified water and solute by specific gravity difference. This separation tank is preferably a tank having a size and a residence time such that the feed liquid is separated into a solute-rich layer and a (coarse) purified water layer, and a flow from each layer is generated.
The coalescer is preferably used when the solute-rich portion separated from the solution shows a state in which the layer does not form two distinct layers. As such a state, for example, a state where a solute-rich portion is dispersed as oil droplets in (coarse) purified water can be exemplified. The coalescer is a tank or tube containing an oil separation filter (for example, a glass cloth, non-woven fabric, etc.) for growing solute-rich droplets to the extent that a layer separated from (coarse) purified water is formed. be able to. The coalescer is designed to have a size and residence time that separates the solute from the water-rich draw solution to produce a solute-rich stream and a (coarse) purified water stream.
The centrifuge is preferably used when the solute is precipitated as a solid from the draw solution.

The nanofilter is preferably a filter having fine pores with a pore diameter of 5 to 50 nm, for example. Such a filter can capture the solute in the aqueous solution passing therethrough and allow only water to pass through.
As the separation and recovery means, only one of the above may be used, or two or more may be connected and used. Only one separation / collection means of the same kind may be used, or two or more may be connected and used. When a plurality of separation and recovery means are connected and used, they may be in series or in parallel, or a combination thereof.
As the separation and recovery means in the forward osmosis water purification unit of this embodiment, either a separation tank, a coalescer, or a centrifuge is used according to the state of separation of the solute-rich portion, or one of these is nano-sized. It is preferable to use a filter connected in series.

[Scale of forward osmosis water purification unit]
The scale of the purified water in the forward osmosis water purification unit is generally determined by the area of the semipermeable membrane.
Here, the amount of purified water generally required for an advanced life is estimated to be about 300 L per household per day. In order to secure this amount of purified water, a water purification scale of 30 L / hour per household is required.
If the number of households in the region unit that enjoys the benefits of the system of the present embodiment is estimated to be about 1 to 20 households, a capacity of 30 to 600 L / hour is required as the water purification scale. In addition, regarding hospital use, considering the scale of the hospital in the area where the system of the present embodiment is assumed, it is thought that clean water equivalent to about 5 to 10 standard households is required. Included in the above range. The area of the semipermeable membrane for enabling the above-described water purification can be calculated to be about 50 to 2,000 m ² . As a more preferable area of the semipermeable membrane in the forward osmosis water purification unit of the present embodiment, for example, a numerical range of 80 to 1,000 m ² can be exemplified. However, as for the area of the semipermeable membrane corresponding to the desired water purification scale, the contributions of the performance of the draw solution and the semipermeable membrane, the compatibility of both, and the water quality level of the raw water to be purified (eg salt concentration) are large. Therefore, the present invention is not limited to the above numerical range.

<Fuel cell unit>
The fuel cell unit in the present embodiment is
It has a reformer that reforms the raw material gas to generate hydrogen, and a fuel cell that generates power by reaction of hydrogen supplied from the reformer and air. In addition to these, for example, a desulfurizer, a humidifier, a selective oxidizer, and the like may be further included.

[Reformer]
The reformer has a function of reforming the raw material gas to generate hydrogen.
As source gas, methane gas, ethane gas, propane gas, butane gas, carbon monoxide gas, coal gas, natural gas, biogas, methanol, ethanol etc. can be used, for example. Of these, methane gas is supplied as city gas, and other liquefied petroleum gas is supplied in the form of filled cylinders.
Such a raw material gas can be reformed by an appropriate method such as steam reforming, partial oxidation reforming, autothermal reforming, or thermal decomposition.
The steam reforming is performed by supplying a raw material gas and steam onto a suitable catalyst. Examples of the reforming catalyst include a catalyst in which nickel, nickel-potassium, noble metal (eg, platinum, rhodium, ruthenium, etc.) is supported on an appropriate carrier (eg, alumina, etc.). The operating temperature can be, for example, 700 to 1,200 ° C.

The partial oxidation reforming is performed by heating the raw material gas together with an appropriate amount of oxygen (air) to a high temperature (for example, 1,200 to 1,500 ° C.) without a catalyst.
The autothermal reforming is performed by supplying a raw material gas, water vapor, and an oxidizing agent (oxygen, air, etc.) onto a suitable catalyst. Examples of the catalyst in this case include a catalyst in which nickel, a noble metal (eg, platinum, rhodium, etc.) is supported on an appropriate carrier (eg, alumina, zirconia, ceria, etc., or a solid solution composed of a plurality of these). it can. The operating temperature can be, for example, 150 to 400 ° C.
Only one reformer that performs such reforming may be used, or a plurality of reformers may be connected in parallel or in series.

[Fuel cell]
The fuel cell in the present embodiment has a function of generating electric power by a reaction between hydrogen supplied from the reformer and oxygen. This fuel cell
An anode supplied with hydrogen generated by the reformer;
A cathode to which oxygen is supplied;
An electrolyte sandwiched between the anode and the cathode;
Have The oxygen may be supplied as air.
The fuel cell in the present embodiment can be of an appropriate system such as a solid polymer fuel cell, a solid oxide fuel cell, an alkaline fuel cell, a phosphoric acid fuel cell, or a molten carbonate fuel cell. Among these, it is preferable to use a polymer electrolyte fuel cell or a solid oxide fuel cell from the viewpoint of power generation, ease of maintenance, operating temperature, and the like.

The polymer electrolyte fuel cell is a fuel cell using an ion conductive polymer membrane (ion exchange membrane) as an electrolyte. As the electrolyte of the solid polymer fuel cell in the present embodiment, for example, a sulfonated fluorine-based polymer is preferable. Specific examples include sulfonated polytetrafluoroethylene.
As an anode of a polymer electrolyte fuel cell, for example, a catalyst in which a platinum catalyst or a ruthenium-platinum alloy catalyst is supported on carbon black;
As the cathode, for example, carbon black carrying a platinum catalyst can be used.
The operating temperature of the polymer electrolyte fuel cell is preferably set to a relatively low temperature from the viewpoint of battery durability, and can be set to, for example, 70 to 100 ° C, and preferably 80 to 90 ° C. By operating the polymer electrolyte fuel cell in such a temperature range, high power generation efficiency and high thermal efficiency as a whole water purification / power supply system can be realized at the same time, which is preferable.

The solid oxide fuel cell is a fuel cell using ion conductive ceramics as an electrolyte. Examples of the electrolyte of the solid oxide fuel cell in the present embodiment include stabilized zirconia and perovskite.
As an anode of a solid oxide fuel cell, for example, zirconia cermet (metal component is preferably nickel) or the like;
Examples of the cathode include noble metals (for example, platinum), electron conductive oxides, and electron / ion conductive ceramics (for example, lanthanum-manganese composite oxide doped with strontium).
The operating temperature of the solid oxide fuel cell is preferably 800 to 1,000 ° C, more preferably 800 to 900 ° C.

In the present embodiment, the fuel cell may be used as a single cell, or may be used as a stack formed by stacking a plurality of bipolar plates, for example.
The electromotive force of a single cell is about 0.75 V in the case of a polymer electrolyte fuel cell, and about 0.8 V in the case of a solid oxide fuel cell. In the application of the present embodiment, it is assumed that an electromotive force of about 15 to 100 V is required. Therefore, it is preferable to use the stack as a stack of about 20 to 120 bipolar plates.
The fuel cell is preferably used in a state of being housed in a suitable manifold.

[Desulfurizer]
Of the above-described source gases, naturally derived ones may contain an organic sulfur compound. Organic sulfur compounds often act as catalyst poisons for fuel cells. Therefore, it is meaningful that the fuel cell unit includes a desulfurizer. When the raw material gas contains an organic sulfur compound, it is preferably desulfurized by a desulfurizer prior to the treatment by the reformer or after the treatment by the reformer.
The desulfurization is preferably performed by a method in which an organic sulfur compound is converted into hydrogen sulfide by a hydrodesulfurization reaction in the presence of a suitable catalyst, and then the hydrogen sulfide is absorbed and removed by a suitable absorbent. Examples of the hydrodesulfurization catalyst include nickel-molybdenum composite oxide and cobalt-molybdenum composite oxide;
Examples of the absorbent include zinc oxide and the like.

[Scale of fuel cell unit]
The scale of the power generation amount in the fuel cell unit is represented by the amount of power (unit: Wh).
Here, the required amount of electric power in the emerging countries is estimated to be about 300 to 400 Wh per household per day.
When the system according to the present embodiment is applied to an emerging country, the following power situation in the emerging country should be considered when setting the amount of power generation. That is, the power situation in emerging countries:
(1) The original absolute amount of power generation capacity is small,
(2) Power demand is large and power supply cannot catch up. (3) Even if power is generated, the grid (power distribution system) is fragile, so it cannot transmit power efficiently.

For the above reasons, the power supply / demand balance is likely to be disrupted, and therefore a power failure is likely to occur. Especially in the summer, there is a tendency for power demand to increase and frequent power outages. As countermeasures in the event of a power failure in emerging countries, it is possible to wait until the power failure is restored or to obtain power from another route. It is possible for the wealthy to have a power source other than general power transmission, but even in this case, they only have lead-acid batteries as an auxiliary power source for the fan and lighting.
The system of the present embodiment is excellent in that it can perform distributed power generation using fuel gas whose supply is relatively stable without relying on an existing distribution grid as a raw material. Therefore, it is possible to stably supply the necessary amount of power not only to ordinary households but also to hospitals and the like that should receive power stably.

  The system of this embodiment can be adapted to the required amount of power generation and water purification, whether it is an independent detached house, a community where detached houses are gathered to some extent, or an apartment where several households are gathered. Select the scale and install. For example, if the number of households in the region unit that enjoys the benefits of the system of the present embodiment is estimated to be about 1 to 20 households, a capacity of 300 to 8,000 Wh / day is required as the scale of power generation. Regarding hospital use, considering the scale of the hospital in the area where the system of the present embodiment is assumed, the necessary power is considered to be about 5 to 10 households of standard households, and thus is included in the above range. . The power generation scale is preferably 500 to 3,000 Wh / day.

<Combination of scale of forward osmosis water purification unit and fuel cell unit>
For the forward osmosis water purification unit and the fuel cell unit, it is preferable to select a combination that is suitable in terms of the amount of heat that these scales give and receive. That is, the forward osmosis water purification unit needs to be large enough to sufficiently cool the fuel cell unit, but needs to be small enough to operate with heat from the fuel cell unit.
In the following, preferred combinations of the two will be described in order for a polymer electrolyte fuel cell and a solid oxide fuel cell having different operating temperatures.
When a polymer electrolyte fuel cell is used as the fuel cell, the power generation capacity is preferably 50 W or more as the power generation amount of the fuel cell with respect to 1 L of the purified water production amount of the forward osmosis water purification unit, and 1,200 to 1,800 W More preferably. In this case, the power generation amount per purified water 1 m ³ becomes approximately 40～60KWh.

  On the other hand, when a solid oxide fuel cell is used as the fuel cell, cooling of the fuel cell unit is essentially unnecessary, and therefore it is not necessary to consider the scale of the forward osmosis water purification unit that meets this requirement based on the cooling capacity standard. In addition, since the operating temperature of the solid oxide fuel cell is sufficiently high, the amount of heat required for the former operation is certain if the forward osmosis water purification unit and the fuel cell unit are combined within the range of the capacity (scale) described above. Secured. Therefore, in this case, it is sufficient to consider the scale of the fuel cell unit only from the viewpoint of heat resistance of the forward osmosis water purification unit. Since the heat resistance temperature of the forward osmosis water purification unit is generally about 200 ° C., it is preferable to employ a combination in which the forward osmosis water purification unit after heat transfer does not reach this temperature.

<System in the present embodiment>
The system in the present embodiment includes each unit as described above. However, it will be apparent to those skilled in the art that in addition to these, a predetermined pump, heat exchanger, and the like should be provided.
In addition to these, the system in the present embodiment may optionally further include other units.
As the other unit, for example, a filter for removing water-insoluble solids from the supplied raw water,
A draw solution tank for temporarily storing the water-rich draw solution after extraction,
A water storage tank for temporarily storing the obtained purified water,
An additional heater that is used as an auxiliary when the temperature is insufficient for the heat quantity of the heat exchanger,
A power conditioner (for example, a DC-DC booster, a DC-AC converter, etc.) for adjusting the generated power to a desired mode;
An indicator lamp indicating the operating state of the system can be mentioned.

The said filter is used in order to remove the water-insoluble solid content which inhibits operation | movement of a forward osmosis water purification unit from the raw | natural water supplied. As this filter, it is preferable that it is a filter unit which has a hole diameter of about 0.01-1 micrometer, for example. A plurality of filter units having different hole diameters or a plurality of filter units having the same hole diameter may be connected in series or in parallel. In order to reduce the frequency of filter clogging and facilitate maintenance, it is preferable to use a filter with a large pore diameter and a filter with a small pore diameter connected in series in this order;
In order to ensure the flow rate of raw water, it is preferable to use a plurality of filters having the same pore diameter connected in parallel.
The additional heater is preferably of a type driven by inexpensive gas. As this gas, the same raw material gas supplied to the fuel cell unit can be used.

<System Operation Principle in this Embodiment>
In the system according to the present embodiment, the forward osmosis water purification unit and the fuel cell unit cooperate in a complementary manner. Specifically, heat exchange is performed between the forward osmosis water purification unit and the fuel cell unit. Preferably, the drive power of the forward osmosis water purification unit is power supplied from the fuel cell unit.
The heat exchange is
The purified water supplied from the forward osmosis water purification unit is used as cooling water for the fuel cell unit, and the purified water after cooling the fuel cell unit is used as a heat source for the forward osmosis water purification unit. Or using a heat medium circulating between the forward osmosis water purification unit and the fuel cell unit,
The heat generated from the fuel cell unit is used as a heat source for the forward osmosis water purification unit.

The cooling water of the fuel cell unit according to one embodiment of the present invention may be purified water supplied from the forward osmosis water purification unit. As purified water for cooling, it is preferable to use purified water obtained from coalescer after being heated to the solute separation temperature of the draw solution. Since this purified water is not subjected to cooling treatment other than natural cooling by heat radiation from the pipe, it shows a temperature slightly lower than the solvent separation temperature. However, when the preferred solute in the present embodiment is used, the solvent separation temperature is about 65 to 80 ° C., while the driving temperature of the fuel cell is preferably 80 to 100 ° C. in the case of a polymer electrolyte fuel cell. In the case of a solid oxide fuel cell, the temperature is about 800 to 1,000 ° C. Therefore, the purified water for cooling functions sufficiently as the cooling water for the fuel cell unit while maintaining the temperature.
Since the temperature of the purified water after cooling the fuel cell unit rises, it can be used as a heat source for the forward osmosis purified water unit. Here, the part which needs to be heated in the forward osmosis water purification unit is a place (only) where the water-rich draw solution is heated to the solute separation temperature after the water is extracted from the raw water in the forward osmosis extraction unit. Here, in a preferable aspect of the present embodiment, the difference between the water extraction temperature and the solute separation temperature is as small as about 10 to 30 ° C. Therefore, heating with purified water after cooling is sufficient.

In another aspect of the present embodiment, heat exchange between the two is performed using a heat medium circulating between the forward osmosis water purification unit and the fuel cell unit. Specifically, the heat generated from the fuel cell unit is recovered by the heat medium, and the heat medium is used as a heat source for the forward osmosis water purification unit.
Examples of the heat medium used here include water, oil, silicon oil, and the like, as well as Dowsum A (Dowtherm A, a liquid that is a mixture of biphenyl and diphenyl ether, a mixing ratio of approximately 3: 7), and the like. Can be used.
The heat medium is preferably circulated in a pipe independent of the water flow in the forward osmosis water purification unit.

  For cooling (heat recovery) of the fuel cell unit, a part of the purified water obtained from the forward osmosis water purification unit and the heat medium may be used in combination. Even in this case, it is preferable that the heat medium be circulated in a pipe independent of the water flow in the forward osmosis water purification unit.

The driving power of the forward osmosis water purification unit in this embodiment is preferably obtained from the power supplied from the fuel cell unit. As a device that requires electric power to drive the forward osmosis water purification unit, a pump for water supply is mainly used. In addition, when the system according to the present embodiment has other electrical equipment such as an indicator lamp, these are also driven by electric power. However, the forward osmosis water purification unit in the present embodiment uses the purified water after cooling the fuel cell unit as a main heat source, as will be described later. Therefore, very little electric power is required to operate the forward osmosis water purification unit.
For example, since the power consumption of the pump for water supply is small, if the hope of the forward osmosis water purification unit and the fuel cell unit is within the above preferred range, the total power of the pump required for the operation of the forward osmosis water purification unit is the fuel Only a small part of the power generation of the battery unit. The power used by the indicator lamp is also extremely small.
As described above, the forward osmosis water purification unit according to the present embodiment can be operated with a small amount of electric power, and therefore, most of the electric power supplied from the fuel cell unit can be used for an intended use outside the system. It is.

Furthermore, when a polymer electrolyte fuel cell is employed as the fuel cell, a part of the purified water obtained from the forward osmosis water purification unit may be used as a humidifying water source for the battery separator.
As described above, in the system according to the embodiment, the forward osmosis water purification unit and the fuel cell unit cooperate with each other in a complementary manner, and can efficiently supply water purification and electric power simultaneously.

Hereinafter, the operation of the water purification / power supply system in the present embodiment will be described with reference to the drawings.
FIG. 1 is a conceptual diagram of one embodiment of a water purification / power supply system having a forward osmosis water purification unit and a fuel cell unit.
The forward osmosis water purification unit separates and collects purified water by removing the solute from the forward osmosis extraction unit where the supply region side and the withdrawal side are adjacent to each other via the forward osmosis membrane (FO membrane) and the drawn solution after extraction. Part. The fuel cell unit has a reformer in addition to the fuel cell. This water purification / power supply system further includes a water circulation mechanism for circulating a part of the obtained purified water as cooling water for the fuel cell, and a plurality of pumps (not shown) necessary for water supply.
Raw water (unpurified water) is introduced into the supply region side of the forward osmosis extraction unit. On the other hand, the draw solution circulates on the drawing side of the forward osmosis extraction unit. In this forward osmosis extraction unit, water in the raw water passes through the semipermeable membrane and is extracted into the draw solution (DS). The driving source for this extraction is the osmotic pressure difference between the raw water and the draw solution.

  The raw water from which water has been extracted and concentrated with impurities is subjected to wastewater treatment. On the other hand, the water-rich draw solution absorbed is heated to the solute separation temperature by a heat exchanger and then sent to the separation and recovery unit. The solute in the draw solution is significantly less water soluble at high temperatures. Therefore, the purified water and the solute in the water rich draw solution are respectively recovered by appropriate separation and recovery means in the separation and recovery unit. The collected purified water is first sent to the water circulation mechanism. The purified water is supplied as a purified water product except that a part of the purified water is circulated and used as cooling water for the fuel cell. The collected solute is subjected to re-preparation of the draw solution.

Hydrogen (H ₂ ) obtained from the fuel gas by the reformer is sent to the anode of the fuel cell, and air (oxygen) is sent to the cathode, and electricity is generated by the fuel cell reaction using these. Since this fuel cell reaction is an exothermic reaction, cooling is required for stable operation. A part of the purified water obtained from the forward osmosis water purification unit is circulated for cooling.
A part of the purified water obtained from the separation and recovery unit is sent to the fuel cell by the water circulation mechanism. The purified water after cooling the fuel cell becomes hot water having a high temperature. This hot water is sent to a heat exchanger and used as a heat source for raising the temperature of the water-rich draw solution to the solute separation temperature. Since the hot water after heat exchange moves through the piping independent of the operation of the fuel cell except for the receipt of heat, the water purity does not deteriorate. Therefore, the hot water after the heat exchange is returned to the water circulation mechanism as it is and joined with the purified water obtained from the separation and recovery unit. The purified water after joining is supplied as a purified water product except that a part of the purified water is circulated and used as cooling water for the fuel cell.

FIG. 2 is a conceptual diagram of another aspect of a water purification / power supply system having a forward osmosis water purification unit and a fuel cell unit.
The system of FIG. 2 is substantially the same as the system of FIG. 1, but differs in that heat exchange between the forward osmosis water purification unit and the fuel cell unit is governed by a heat medium independent from both systems.
In the system of FIG. 2, all of the purified water recovered from the water-rich draw solution and obtained through the separation and recovery unit is supplied as a purified water product. The heat medium is circulated by a heat medium circulation mechanism to control heat exchange between the forward osmosis water purification unit and the fuel cell unit. The heat medium sent to the fuel cell at a low temperature receives heat from the fuel cell and is in a high temperature state. This high-temperature heat medium is sent to a heat exchanger and used as a heat source for raising the temperature of the water-rich draw solution to the solute separation temperature. The hot water after the heat exchange becomes a low temperature again, is returned to the heat medium circulation mechanism along the heat medium return line, and is recycled. Since this heat medium only circulates in the pipe independent of the flow of water in the forward osmosis water purification unit, the purified water obtained from the forward osmosis water purification unit is not contaminated.

In any case, it is preferable to use a part of electricity obtained from the fuel cell as a pump drive source necessary for water supply. Since the power consumption of the pump for water supply is small, the fuel cell can supply a sufficient amount of electricity even if part of the obtained electricity is accommodated in the water pump.
Thus, the water purification / power supply system in the present embodiment uses fuel gas (usually inexpensive) and air by the forward osmosis water purification unit and the fuel cell unit functioning in a complementary manner, Purified water and electric power can be supplied efficiently.

Hereinafter, the present embodiment will be described more specifically, and the effect will be verified by computer simulation.
The first verification example was performed for the water purification / power supply system shown in FIG. In FIG. 3, the numbers surrounded by diamonds are sampling points for mass balance measurement. The water samples obtained from each of these sampling points are hereinafter referred to as “Sample 1” or the like. For example, a water sample sampled at the point of the number “1” in the diamond box will be referred to as “sample 1”.
The solute of the draw solution in the forward osmosis water purification unit is a polyethylene glycol-polypropylene glycol copolymer (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name “Epan 450”, weight average molecular weight 2,400), and at the forward osmosis extraction unit (FO) inlet. The solute concentration was adjusted to 90.0% by mass for use.
As raw water, it was decided to supply low quality tap water (water supply in Thane, India) containing 0.3% by mass of salt. The supply temperature was 25 ° C.

Raw water is first introduced into a filter to remove water-insoluble solids (sample 1). Here, in order to prevent the system from becoming unstable due to the supply flow rate of the raw water being insufficient, circulation is performed to return a part of the supply water that has passed through the filter to the filter so that the supply flow rate becomes constant. Considered.
The raw water after passing through the filter is then introduced into the supply side region of the forward osmosis extraction unit (FO). In the forward osmosis water purification unit, the supply side region and the drawing side region through which the draw solution flows are adjacent to each other via a semipermeable membrane (area 100 m ² ). In this forward osmosis extraction unit, water in the raw water passes through the semipermeable membrane and is extracted into the draw solution (DS). Here, the water flow is divided into a flow of a water-rich draw solution (sample 2) containing extraction water and a flow of concentrated brine (sample 3) in which a part of the water is extracted and removed to concentrate the salt. The concentrated brine is drained.

  Next, the water-rich draw solution is sent to a draw solution tank, and after being merged with a later-described recovered draw solution (recovered DS), it is sent to the next step (sample 4). The temperature of the sample at this point was 37.2 ° C. The water rich draw solution stream is sent to two heat exchangers (Ecomizers 1 and 2) in parallel and heated. The solution flow temperature after recombination was 59.0 ° C. Furthermore, it heats to 70.0 degreeC with the heat exchanger (separation heat exchange) for heating to the solute separation temperature of a draw solution. The water-rich draw solution after heating is introduced into the coalescer.

In the coalescer, the water rich draw solution is
A stream from the top where the salinity is removed and further substantially free of solute polypropylene glycol;
A flow from the bottom containing a high concentration of polypropylene glycol;
To separate. This flow (sample 6) from the lower part is sent to the heat exchanger (Ecomizer 1), and after releasing the heat for heating the water-rich draw solution stream, it enters the extraction side region of the forward osmosis extraction unit (FO). Introduced and used for extraction of water in the raw feed water.
On the other hand, the flow (sample 5) from the top of the coalescer is crude purified water substantially free of salt and polypropylene glycol. This crude purified water is sent to a heat exchanger (Ecomizer 2), which releases heat for heating the water-rich draw solution stream and then sent to the nanofilter (NF).

  The nanofilter removes the remaining polypropylene glycol in the crude purified water to obtain purified water (sample 7). This purified water is sent to a water storage tank, temporarily stored, then supplied as, for example, drinking water (sample 11), and a part thereof is diverted to the cooling water of the fuel cell unit as will be described later. A solution (sample 8) containing a small amount of polypropylene glycol collected from the nanofilter is sent to a draw solution tank as a collected draw solution, and merges with the water-rich draw solution.

In this verification example, sulfo ion exchange resin is used as the electrolyte;
Carbon black carrying a ruthenium-platinum alloy catalyst as the anode; and carbon black carrying platinum as the cathode,
It was decided to use the polymer electrolyte fuel cell that each had.
The operating temperature of the fuel cell was 80 ° C., and liquefied propane gas (LPG) and air were used as the raw material gas.

The liquefied natural gas is sent to a reformer equipped with a nickel-based catalyst. The hydrogen generated by the reformer is sent to the anode side of the fuel cell (PEFC) and the air is sent to the cathode side to generate electricity.
As the cooling water for the fuel cell unit, a part of the purified water obtained by the forward osmosis water purification unit was used. The temperature of the purified water for cooling was 58.1 ° C. (Sample 9). The purified water for cooling is heated to 75.0 ° C. after cooling the power generated by the fuel cell. The purified water for cooling is then sent to a heat exchanger (separation heat exchange), used as a heating heat source for the water-rich draw solution flow, and then merged with purified water (sample 10) and sent to a water storage tank. The purified water for cooling is only circulated in the pipe independent from the operation of the fuel cell except for the receipt of heat, so the water purity does not deteriorate. Therefore, the purified water for cooling after use can be used as it is with the purified water.
This system is provided with an additional heater (Boost Heater) driven by a raw material gas, but it was not necessary to operate the additional heater in this verification example.

Tables 1 to 5 show the operating conditions for the above water purification and power supply systems.
The mass balance is shown in Table 6, respectively.

  As shown in the above table and diagram, the water purification / power supply system in this verification example uses 30 kg / h purified water (drinking water) and 1,834 kWh using raw water (low quality tap water) and 0.41 kg / h LPG. Was able to get the power.

Next, a system that performs heat exchange using a heat medium circulating between the forward osmosis water purification unit and the fuel cell unit was similarly verified by computer simulation. This verification example was performed for the water purification / power supply system shown in FIG.
The system of FIG. 4 is generally similar to the system of FIG. 3 described above, but the heat flow between the forward osmosis water purification unit and the fuel cell unit is separate from the water flow in the forward osmosis water purification unit. The difference is that the heat medium that circulates in the independent pipes controls. As this heat medium, purified water produced regardless of the operation of this system was used.
Purified water (sample 7) obtained from the upper part of the coalescer and passed through the nanofilter is sent to a water storage tank and used exclusively for a predetermined application (for example, drinking water).

An independent circulating heat medium was used for cooling the fuel cell unit in this system.
The temperature of this heating medium was 62.7 ° C. (Sample 9). The heat medium is cooled to the power generated by the fuel cell, then heated to 75.0 ° C., and then sent to a heat exchanger (separation heat exchange) to be used as a heating heat source for the water-rich draw solution flow. The heat medium temperature at the separation heat exchange outlet was 63.5 ° C. This heating medium continues to circulate by the pump D without joining with purified water, and is used for cooling the fuel cell unit.
This system also includes an additional heater (Boost Heater) driven by the raw material gas, but it was not necessary to operate the additional heater in this verification example.

Tables 7 to 11 show the operating conditions for the above water purification and power supply systems.
The mass balance is shown in Table 12, respectively.

  The water purification and power supply system in this verification example can obtain 30 kg / h of purified water (drinking water) and 1,339 kWh of power using raw water (low quality tap water) and 0.299 kg / h of LPG. It was.

  As understood from these results, in the water purification / power supply system in the present embodiment, the forward osmosis water purification unit and the fuel cell unit function in a complementary manner, and each of the water purification and electric power efficiency is achieved as an independent system. Can be supplied automatically. Therefore, it was verified that these water purification and power supply systems can be effectively applied to establish living infrastructures in remote areas, undeveloped land, and emerging countries where basic infrastructure is not established.

Claims (9)

A system for supplying purified water and power having a forward osmosis water purification unit and a fuel cell unit,
The system according to claim 1, wherein heat exchange is performed between the forward osmosis water purification unit and the fuel cell unit. The heat exchange is
Using purified water supplied from the forward osmosis water purification unit as cooling water for the fuel cell unit, and using purified water after cooling the fuel cell unit as a heat source for the forward osmosis water purification unit, The system of claim 1. The heat exchange is
Using a heat medium that circulates between the forward osmosis water purification unit and the fuel cell unit,
The system according to claim 1, wherein the system is performed by using heat generated from the fuel cell unit as a heat source of the forward osmosis water purification unit.   The system according to any one of claims 1 to 3, wherein the drive power of the forward osmosis water purification unit is power supplied from the fuel cell unit. The forward osmosis water purification unit is
The osmosis extraction part adjacent to the supply side area through which the raw water to be circulated flows and the draw-out area through which the draw solution circulates through the semipermeable membrane, and the drawn solution after the extraction are separated and recovered. The system as described in any one of Claims 1-4 which has a separation-and-recovery part to perform.   The solute of the draw solution in the forward osmosis water purification unit is selected from a solute consisting of a diol (co) polymer and a solute consisting of a combination of a volatile cation source and a volatile anion source. A system according to claim 1. The fuel cell unit is
The system according to claim 1, further comprising: a reformer that reforms a source gas to generate hydrogen; and a fuel cell that generates power by a reaction between hydrogen supplied from the reformer and air.   The system according to claim 7, wherein the fuel cell is a solid polymer fuel cell or a solid oxide fuel cell. A method for supplying purified water and power using a system having a forward osmosis water purification unit and a fuel cell unit,
The method according to claim 1, wherein heat exchange is performed between the forward osmosis water purification unit and the fuel cell unit.

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