JP2011041874A - Water treatment device for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment device for a fuel cell which enables long-term operation of a fuel cell by inhibiting the propagation of bacteria caused by the long-term operation. <P>SOLUTION: The water treatment device for a fuel cell uses an ion exchange resin. In the ion exchange resin, ions of the ion exchange resin are substituted with at least one of silver ions, copper ions, and zinc ions by passing a solution containing at least one of silver, copper, and zinc therethrough. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technology of a water treatment device for a fuel cell using an ion exchange resin.

  A fuel cell requires hydrogen, and in order to produce hydrogen from city gas, natural gas, or the like, water is required in the reforming process, and pure water is used. Pure water is also used for cooling the fuel cell and humidifying the polymer membrane of the polymer electrolyte fuel cell.

  Pure water is usually produced by removing impurity ions using a water treatment apparatus equipped with an ion exchange resin. In addition to producing pure water from tap water, various techniques for treating condensed water generated by the power generation reaction of the fuel cell and circulating the treated water (pure water) to the fuel cell have been proposed (see, for example, Patent Document 1). ing.

  Since fuel cells are being developed with the goal of long-term operation, water treatment devices used for the fuel cells are also expected to operate for a long time. And since the water utilized with a fuel cell contacts with the air taken in from the outside air, depending on the installation environment, bacteria may enter the water treatment device via the air and grow. If the bacteria grow in the water treatment apparatus, not only the desired water quality cannot be obtained, but also there is a possibility that stable treatment water cannot be supplied due to clogging.

  Conventionally, several methods for suppressing bacterial propagation in a water treatment apparatus have been proposed (see, for example, Non-Patent Document 1 and Patent Document 2).

  Non-Patent Document 1 shows that the use of an OH-type anion exchange resin has an effect of suppressing bacterial growth. The reason is that the OH type anion exchange resin exhibits strong alkalinity. Non-Patent Document 1 discloses that OH type and H type mixed bed resins have higher sterilization ability than OH type ion exchange resins alone. The reason is that, when bacteria pass through the resin, they are in random contact with the OH type and H type and undergo a large pH change.

  Patent Document 2 discloses a technique for suppressing bacterial growth by mixing an antibacterial agent such as activated carbon supporting silver with an ion exchange resin.

JP-A-8-17457 Japanese Patent Laid-Open No. 10-314727

Toshio Sato et al., Electrochemistry and Industrial Physical Chemistry, 54 (3), 1986, pp. 269-273

  However, even if an OH-type ion exchange resin is used in a water treatment apparatus as in Non-Patent Document 1, a large amount of carbonic acid is present in the condensed water generated by the power generation reaction of the fuel cell, and the condensed water does not pass through. If water is used, the OH type ion exchange resin is replaced with the carbonate type. That is, in the initial use, since the ion exchange resin is OH type, the propagation of bacteria is suppressed, but the ion exchange resin becomes a carbonic acid type by long-term use, so it is difficult to suppress the growth of bacteria. It becomes. Therefore, it can be said that it is not very effective in long-term use of the water treatment apparatus. Further, even if OH type and H type mixed bed resin is used in the water treatment apparatus as in Non-Patent Document 1, as described above, the OH type ion exchange resin is replaced with the carbonic acid type. It can be said that it is not very effective in long-term use.

  Further, when an ion exchange resin mixed with an antibacterial agent supporting silver as in Patent Document 2 is used in a water treatment apparatus, the eluate and crushed material from activated carbon are mixed into the treated water, affecting the power generation performance of the fuel cell. As a result, it is not very effective for long-term operation.

  An object of the present invention is to provide a water treatment device for a fuel cell that suppresses bacterial growth caused by long-term operation of the fuel cell and enables long-term operation.

  The present invention is a water treatment apparatus for a fuel cell using an ion exchange resin, wherein the ion exchange resin passes through a solution containing at least one of silver, copper, and zinc, thereby performing ion exchange. Resin ions are substituted with at least one of silver ions, copper ions, and zinc ions.

  In the water treatment apparatus for a fuel cell, the ion exchange resin includes a cation exchange resin, and the solution is selected from at least one of a nitrate solution, a sulfate solution, a chloride solution, and a complex salt solution. It is preferable.

  Further, in the water treatment apparatus for a fuel cell, the ion exchange resin includes a strong acid cation exchange resin, and the solution includes at least one of a nitrate solution, a sulfate solution, a chloride solution, and a complex salt solution. Preferably it is selected.

  In the water treatment apparatus for a fuel cell, it is preferable that the ion exchange resin includes an anion exchange resin, and the solution is a complex salt solution.

  In the water treatment apparatus for a fuel cell, the anion exchange resin is preferably a strongly basic anion exchange resin having a trimethylammonium group as an exchange group.

  Moreover, in the water treatment apparatus of the fuel cell, by passing the complex salt solution through the ion exchange resin, the ions of the ion exchange resin are replaced with at least one of silver ions, copper ions, and zinc ions. Thereafter, it is preferable to deposit silver, copper or zinc on the surface and inside of the ion exchange resin by reduction treatment.

  In the water treatment apparatus for a fuel cell, the degree of crosslinking of the strong acid cation exchange resin is preferably 12% or more.

  Further, in the water treatment apparatus of the fuel cell, the ion exchange resin includes a mixed bed resin of a strong acid cation exchange resin and a strongly basic ion exchange resin, and the average particle size of the strong acid cation exchange resin is It is preferably 80% or less of the average particle size of the strongly basic ion exchange resin.

In the water treatment apparatus for a fuel cell, the ion exchange resin includes a strong acid cation exchange resin, and silver ions or complex ions containing silver occupy the total exchange capacity of the strong acid cation exchange resin in an initial state. The ratio is preferably equal to or less than the value (R _Ag ) determined by the following formula (1).
C _Ag = 37 exp (−2.4 pH) R _Ag ³ +82 exp (−2.0 pH) R _Ag ² +110,000 exp (−2.3 pH) R _Ag (1)
(Where C _Ag is the desired silver concentration of the water treatment device outlet side treated water of the fuel cell (where C _Ag = 0.001 to 10 ppb), pH is the water to be treated on the fuel cell water treatment device inlet side) Hydrogen ion index (where pH = 4 to 6), R _Ag is silver ion or complex ion containing silver (eq / L) in the total exchange capacity (eq / LR) of the strongly acidic cation exchange resin -R) (%)

  ADVANTAGE OF THE INVENTION According to this invention, the water treatment apparatus of the fuel cell which suppresses the reproduction of the bacteria which arise by long-term operation of a fuel cell, and enables long-term operation can be provided.

It is a schematic diagram which shows an example of a structure of the water treatment apparatus of the fuel cell which concerns on this embodiment. It is a figure which shows the relationship between _RAg and _CAg in various hydrogen ion exponents (pH).

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  FIG. 1 is a schematic diagram illustrating an example of a configuration of a water treatment apparatus for a fuel cell according to the present embodiment. The fuel cell water treatment device 10 shown in FIG. 1 includes a cartridge filled with an ion exchange resin. There may be one or more cartridges. The ion exchange resin filled in the cartridge is an anion exchange resin, a cation exchange resin, a mixed bed resin of an anion exchange resin and a cation exchange resin, or the like.

  The fuel cell water treatment device 10 according to the present embodiment mainly removes impurity ions in water supplied to the fuel cell 12. Examples of water to be treated by the fuel cell water treatment apparatus 10 include tap water (city water), pure water, and condensed water generated by the power generation reaction of the fuel cell 12. Examples of impurity ions contained in water include carbonate ions, hydrogen carbonate ions, chloride ions, and sulfate ions.

  City water such as tap water is supplied to the water treatment device 10 of the fuel cell from the treated water line 14. Further, the condensed water discharged from the fuel cell 12 is temporarily stored in, for example, the condensed water tank 16 and is supplied from the condensed water line 20 to the water treatment device 10 of the fuel cell by the pump 18. And city water, condensed water, etc. are passed through the ion exchange resin of the water treatment apparatus 10 of a fuel cell, and the impurity ion in water will be removed.

The treated water from which the impurity ions have been removed (pure water) is supplied from the treated water line 22 to the fuel cell 12. The treated water may be, for example, cooling of a fuel cell, humidification of a polymer membrane in the case of a solid polymer fuel cell, etc., and in the case of a solid oxide fuel cell, city gas or the like is converted into carbon monoxide (CO ) And hydrogen gas (H ₂ ).

  The ion exchange resin used in the present embodiment is made to pass through a solution containing at least one of silver, copper, and zinc, so that ions of the ion exchange resin are at least of silver ions, copper ions, and zinc ions. Those substituted by any one (hereinafter may be referred to as a silver-type ion exchange resin, a copper-type ion exchange resin, or a zinc-type ion exchange resin) are used. By using such a silver-type ion exchange resin, a copper-type ion exchange resin, and a zinc-type ion exchange resin, even if bacteria are mixed in the water treatment device of the fuel cell, the propagation is suppressed. Long-term operation is possible.

  The time, temperature, and the like for allowing a solution containing at least one of silver, copper, and zinc to pass through (contact with) the ion exchange resin are silver type ion exchange resins (copper type ion exchange resin, zinc type What is necessary is just to select the optimal conditions so that the silver ion (copper ion, zinc ion) which occupies for the total exchange capacity of an ion exchange resin) may reach a desired ratio.

  The proportion of silver ions (copper ions, zinc ions) in the total exchange capacity of the silver type ion exchange resin (copper type ion exchange resin, zinc type ion exchange resin) is 0.01% or more and less than 90%. The range is preferable, and the range of 0.1% to 70% is more preferable. If the proportion of silver ions in the total exchange capacity of the silver-type ion exchange resin (similar to copper and zinc types) is less than 0.01%, the bacteria mixed in the water treatment device of the fuel cell are sufficiently propagated. If it is 90% or more, the elution amount of silver ions (copper ions, zinc ions) into the treated water discharged from the water treatment device of the fuel cell may increase. This is because the condensed water of a fuel cell contains a lot of carbonic acid and may show acidity. Such acidic water, that is, water containing a large amount of hydrogen ions, is a silver-type, copper-type or zinc-type ion exchange resin. It is thought that this is because an exchange reaction occurs with silver ions, copper ions or zinc ions adsorbed on the ion exchange group when the water is passed through. If treated water containing eluted silver ions or the like is supplied to the fuel cell, it may affect long-term operation.

  When the ion exchange resin is a cation exchange resin as a solution containing at least one of silver, copper and zinc, a nitrate solution (a silver nitrate solution, a copper nitrate solution, a zinc nitrate solution, etc.), a sulfate solution (Silver sulfate solution, copper sulfate solution, zinc sulfate solution, etc.), chloride solution (silver chloride solution, copper chloride solution, zinc chloride solution, etc.), complex salt solution (silver complex salt solution, copper complex salt solution, zinc complex salt solution, etc.) Preferably, at least one of them is selected.

  Further, as a solution containing at least one of silver, copper and zinc, when the ion exchange resin is a strong acid cation exchange resin, a nitrate solution, a sulfate solution, a chloride solution, or a complex salt solution It is preferable that at least any one is selected.

  Furthermore, when a strongly acidic ion exchange resin is used as the ion exchange resin, the degree of crosslinking is preferably 12% or more. When the degree of crosslinking of the strongly acidic ion exchange resin is less than 12%, silver ions (copper ions, zinc ions) may be eluted in the treated water discharged from the water treatment device of the fuel cell.

  When the ion exchange resin is an anion exchange resin as a solution containing at least one of silver, copper and zinc, a complex salt solution is preferable. Further, from the viewpoint of impurity ion removal performance, the anion exchange resin is preferably a strongly basic anion exchange resin having a trimethylammonium group as an exchange group.

  In the present embodiment, when a cation exchange resin or an anion exchange resin (particularly a strongly basic ion exchange resin having a trimethylammonium group as an exchange group) is used as the ion exchange resin, silver, copper and zinc are used as the ion exchange resin. A complex salt solution is passed (contacted) as a solution containing at least one of the above, and the ion of the ion exchange resin is replaced with at least one of silver ion, copper ion and zinc ion, and then silver ion, copper ion Ions and zinc ions may be reduced to deposit at least one of silver, copper and zinc on the surface and inside of the ion exchange resin. Thus, by carrying out the reduction treatment after ion exchange, it is possible to suppress the growth of bacteria mixed in the water treatment device of the fuel cell even when using an ion exchange resin in which silver, copper and zinc are deposited. . As a result, long-term operation of the water treatment device for fuel cells becomes possible.

The reduction treatment may be performed by bringing a reducing gas such as H ₂ gas into contact with the ion exchange resin, but the reduction treatment using the reducing gas requires a treatment at a relatively high temperature for a long time. For this reason, a reduction treatment by a wet method, which is relatively mild and can be performed in a short time, is preferable. The wet reduction treatment is performed, for example, by passing (contacting) a solution obtained by dissolving a reducing agent in an ion exchange resin.

  As the reducing agent, hydrazine, hydrogen peroxide, ascorbic acid, sodium ascorbate, formaldehyde, formic acid, sodium formate, sodium borohydride and the like can be used.

  The contact time, temperature, pH, and the like with the reducing agent-containing solution when silver, copper, and zinc are precipitated are appropriately set depending on the ion species to be deposited, the type of the reducing agent, and the like. In addition, when the amount of silver, copper, and zinc deposited is insufficient in one ion exchange and reduction treatment of silver ions, copper ions, and zinc ions, the ion exchange and reduction treatment is performed until the desired amount of precipitation is reached. It is preferable to repeat.

  In this embodiment, when using a mixed acid resin of strong acidic cation exchange resin and strong basic ion exchange resin, the average particle size of strong acid cation exchange resin is the average particle size of strong basic anion exchange resin. It is preferable that it is 80% or less. This is because the specific gravity of cation exchange resin and anion exchange resin is different (generally, the specific gravity of cation exchange resin is larger than that of anion exchange resin). When ion exchange resin is used, both ion exchange resins may be separated due to vibration associated with transportation, installation, operation, etc. of the water treatment apparatus, and impurity ions in the water supplied to the fuel cell may not be sufficiently removed.

In the present embodiment, when a strong acid cation exchange resin is used, the ratio of silver ions or complex ions containing silver to the total exchange capacity of the strong acid cation exchange resin in the initial state is obtained by the following equation (1). It is preferable that it is below a value (R _Ag ). Equation (1) is calculated from FIG. 2 showing the relationship between R _Ag and C _{Ag at} various hydrogen ion exponents (pH).
C _Ag = 37 exp (−2.4 pH) R _Ag ³ +82 exp (−2.0 pH) R _Ag ² +110,000 exp (−2.3 pH) R _Ag (1)
(Where C _Ag is the desired silver concentration of the water treatment device outlet side treated water of the fuel cell (where C _Ag = 0.001 to 10 ppb), pH is the water to be treated on the fuel cell water treatment device inlet side) Hydrogen ion index (where pH = 4 to 6), R _Ag is silver ion or complex ion containing silver (eq / L) in the total exchange capacity (eq / LR) of the strongly acidic cation exchange resin -R) (%)

When the ion exchange resin used in the water treatment apparatus exceeds the value (R _Ag ) obtained by the equation (1), the silver ions in the treated water discharged from the water treatment apparatus of the fuel cell exceed a desired concentration. Elution easily.

  As described above, in the fuel cell water treatment device of the present embodiment, even if bacteria are mixed in the fuel cell water treatment device, the sterilization action of silver ions, copper ions, and zinc ions adsorbed on the ion exchange resin Thus, since the growth of bacteria can be suppressed, the water treatment apparatus can be operated for a long time. That is, if the condensed water generated by the power generation reaction of the fuel cell is processed by the water treatment device of the fuel cell of the present embodiment, and the treated water is supplied to the fuel cell and reused, the fuel cell can be stabilized for a long time. Driving is possible. When the condensed water is circulated and used, it is preferable that the gas contained in the condensed water is discharged to the atmosphere, then processed by the water treatment device 10 and supplied to the fuel cell 12.

  In the fuel cell 12, fuel gas (for example, city gas) and air (containing oxygen) are supplied to the fuel cell 12 from the fuel supply line 24 and the air supply line 26, respectively, and electricity is generated. Since the fuel cell 12 generates power at a high temperature, for example, the heat exchanger 28 can also supply hot water by exchanging the generated exhaust heat with condensed water and tap water.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

(Examples 1 and 2)
The apparatus shown in FIG. 1 was used to treat the condensed water discharged from the solid oxide fuel cell. The concentration of CO ₂ dissolved in the condensed water was about 16 ppm, the concentration of chloride ions was about 100 ppb, and the pH of the condensed water was 5. As the ion exchange resin filled in the cartridge, an ion exchange resin in which 30 mL of a strongly basic anion exchange resin having a trimethylammonium group as an exchange group and 10 mL of a strongly acidic cation exchange resin was mixed and packed was used. As the strongly basic anion exchange resin of Examples 1 and 2, an OH type strongly basic anion exchange resin (Amberjet 4002 (OH)) was used. In addition, the strongly acidic cation exchange resin of Example 1 uses a cation exchange resin (Amberjet 1024 (H)) having a crosslinking degree of 12%, and 1500 mL of a 0.15 ppb AgNO ₃ aqueous solution is passed through the resin. This is converted to Ag type, and the proportion of silver ions in the total exchange capacity of the cation exchange resin is adjusted to 9%. The strongly acidic cation exchange resin of Example 2 uses a cation exchange resin (Amberjet 1024 (H)) having a crosslinking degree of 12%, and 1500 mL of a 10 g / L AgNO ₃ aqueous solution is passed through the resin to obtain an Ag type. The ratio of silver ions in the total exchange capacity of the cation exchange resin is adjusted to 90% or more.

  In both Examples 1 and 2, the water to be treated was passed through the ion exchange resin in a downward flow. After 10 days of operation, the treated water treated with the ion exchange resin was sampled, the silver ion concentration and the chloride ion concentration were measured, and the presence or absence of bacteria was examined. The results are summarized in Table 1.

(Comparative example)
The comparative example was the same as Example 1 except that a strongly acidic cation exchange resin not converted to Ag type was used.

  As can be seen from Table 1, in Examples 1 and 2 using the strongly acidic cation exchange resin converted to Ag type, bacteria were hardly generated even after 10 days of operation, but not converted to Ag type. In a comparative example using a strongly acidic cation exchange resin, generation of bacteria was observed. In Example 2 in which the ratio of silver ions in the total exchange capacity of the cation exchange resin was adjusted to 90% or more, the treated water contained about 1000 ppb of silver ions, but the total exchange capacity of the cation exchange resin In Example 1 in which the proportion of silver ions in the water was adjusted to 9%, the silver ions in the treated water could be suppressed to 10 ppb or less. In Examples 1 and 2 and the comparative example, the chloride ion concentration in the treated water was 10 ppb or less, and the chloride ions could be sufficiently removed.

To _{C Ag} = 37exp _^(-2.4pH) wherein the ^{R Ag 3 + 82exp (-2.0pH)} R Ag 2 + 110000exp (-2.3pH) R Ag, Applying _pH5, C _Ag 10ppb, _R Ag is 9. 4%. That is, in order to treat the water to be treated having a pH of 5 so that the silver ion concentration in the treated water is 10 ppb or less, the ratio of silver ions in the total exchange capacity of the anion exchange resin is 9.4% or less. There is a need to. And the said Example 1 is satisfy | filling that it is below the value calculated from said formula. Therefore, it can be seen that Example 1 is more suitable for long-term operation than Example 2.

(Examples 3 and 4)
In Example 3, a strongly acidic cation exchange resin (Amberjet 1024 (H)) having a crosslinking degree of 8% was used, and 1500 mL of 0.27 ppb AgNO ₃ aqueous solution was passed through this resin to convert it into an Ag type, The test was performed in the same manner as in Example 1 except that the ratio of silver ions in the total exchange capacity of the ion exchange resin was adjusted to 9%. After 10 days of operation, the treated water treated with the ion exchange resin was sampled, the silver ion concentration was measured, and the presence or absence of bacteria was examined. The results are summarized in Table 2.

  As can be seen from Table 2, Example 3 using a strongly acidic cation exchange resin having a crosslinking degree of 8% was compared with Example 1 using a strongly acidic cation exchange resin having a crosslinking degree of 12%. The elution of silver ions into the treated water increased. Therefore, in order to suppress the elution of silver ions into the treated water, it has been found that it is preferable to use a strongly acidic cation exchange resin having a crosslinking degree of 12% or more.

  DESCRIPTION OF SYMBOLS 10 Water treatment apparatus, 12 Fuel cell, 14 To-be-treated water line, 16 Condensed water tank, 18 Pump, 20 Condensed water line, 22 Treated water line, 24 Fuel supply line, 26 Air supply line, 28 Heat exchanger.

Claims (9)

  A water treatment apparatus for a fuel cell using an ion exchange resin, wherein the ion exchange resin passes through a solution containing at least one of silver, copper, and zinc to thereby remove ions of the ion exchange resin. A water treatment device for a fuel cell, wherein the water treatment device is substituted with at least one of silver ions, copper ions, and zinc ions.   2. The water treatment apparatus for a fuel cell according to claim 1, wherein the ion exchange resin includes a cation exchange resin, and the solution is at least one of a nitrate solution, a sulfate solution, a chloride solution, and a complex salt solution. A water treatment device for a fuel cell, wherein the water treatment device is selected from the two.   2. The water treatment apparatus for a fuel cell according to claim 1, wherein the ion exchange resin includes a strong acid cation exchange resin, and the solution is at least one of a nitrate solution, a sulfate solution, a chloride solution, and a complex salt solution. A water treatment device for a fuel cell, wherein the water treatment device is selected from any one of the above.   The water treatment apparatus for a fuel cell according to claim 1, wherein the ion exchange resin includes an anion exchange resin, and the solution is a complex salt solution.   5. The water treatment apparatus for a fuel cell according to claim 4, wherein the anion exchange resin is a strongly basic anion exchange resin having a trimethylammonium group as an exchange group.   The water treatment apparatus for a fuel cell according to claim 2, 4 or 5, wherein the ion of the ion exchange resin is converted into silver ions, copper ions and zinc ions by passing the complex salt solution through the ion exchange resin. A water treatment apparatus for a fuel cell, wherein silver, copper, or zinc is deposited on the surface and inside of the ion exchange resin by reduction after substitution with at least one of them.   The water treatment apparatus for a fuel cell according to claim 3, wherein the cross-linking degree of the strong acid cation exchange resin is 12% or more. The water treatment apparatus for a fuel cell according to claim 1, wherein the ion exchange resin includes a mixed bed resin of a strongly acidic cation exchange resin and a strongly basic ion exchange resin,
An average particle size of the strongly acidic cation exchange resin is 80% or less of an average particle size of the strongly basic ion exchange resin. The water treatment apparatus for a fuel cell according to claim 1, wherein the ion exchange resin includes a strong acid cation exchange resin, and silver ions or silver occupying the total exchange capacity of the strong acid cation exchange resin in an initial state. A water treatment apparatus for a fuel cell, wherein a ratio of complex ions to be contained is not more than a value (R _Ag ) obtained by the following formula (1).
C _Ag = 37 exp (−2.4 pH) R _Ag ³ +82 exp (−2.0 pH) R _Ag ²
+ 110,000exp (−2.3pH) R _Ag (1)
(Where C _Ag is the desired silver concentration of the water treatment device outlet side treated water of the fuel cell (where C _Ag = 0.001 to 10 ppb), pH is the water to be treated on the fuel cell water treatment device inlet side Hydrogen ion index (where pH = 4 to 6), R _Ag is silver ion or complex ion containing silver (eq / L) in the total exchange capacity (eq / LR) of the strongly acidic cation exchange resin -R) (%)

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