JP5551944B2 - Water treatment device for fuel cell - Google Patents

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 the production of 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.

  For example, Patent Document 1 discloses an anion exchange resin, a cation exchange resin in a water treatment apparatus for treating carbonate ions and hydrogen carbonate ions (hereinafter referred to as carbonate ions or simply carbonic acid) in cooling water supplied to a fuel cell. The usage ratio and the technology using mixed bed resin are disclosed.

JP-A-8-17457

  However, since anion exchange resin and cation exchange resin have different specific gravities, a water treatment apparatus using a mixed bed resin of anion exchange resin and cation exchange resin can be used for transportation, installation, operation, etc. of the water treatment apparatus. The accompanying vibration causes the cation exchange resin having a large specific gravity to move to the lower part and the anion exchange resin having a low specific gravity to move to the upper part, so that both ion exchange resins are separated. When the separated mixed bed resin is used in a water treatment device for a fuel cell that is often operated at a high temperature and a low flow rate, trimethylamine is mainly produced from anion exchange resin, and polystyrene sulfonic acid is produced mainly from cation exchange resin. May elute. For example, if the water to be treated is passed in a downward flow, the elution components from the cation exchange resin in the lower part are not captured, and if the water to be treated is passed in an upward flow, the anion exchange resin in the upper part is The elution component is not captured. As a result, the TOC in the treated water increases. If these elution components are mixed into the treated water and the TOC in the treated water increases, the required water conductivity cannot be achieved, or these elution components and these elution components can be used as the production source. Ammonium ions, nitrate ions, nitrite ions, sulfate ions, etc. may adversely affect the power generation performance and life of the fuel cell.

  The objective of this invention is providing the water treatment apparatus for fuel cells which can reduce the impurity ion density | concentration in the water supplied to a fuel cell effectively.

  The present invention is a water treatment apparatus for a fuel cell using an ion exchange resin, wherein the ion exchange resin includes a mixed bed resin of a cation exchange resin and an anion exchange resin, and the average particle diameter of the cation exchange resin Is 0.2 mm or more and 80% or less of the average particle diameter of the anion exchange resin.

  In the fuel cell water treatment apparatus, the volume of the anion exchange resin is preferably 1.5 to 5 times the volume of the cation exchange resin.

  In the fuel cell water treatment apparatus, the ratio of chloride ions to the total exchange capacity of the anion exchange resin in the initial state is preferably 10% or less.

  In the fuel cell water treatment apparatus, the proportion of chloride ions in the total exchange capacity of the anion exchange resin in the initial state decreases as the concentration of carbonic acid dissolved in the water to be treated increases. The desired chlorine concentration is preferably set so as to decrease as the desired chlorine concentration decreases.

Further, in the water treatment apparatus for a fuel cell, the anion exchange resin includes a strongly basic anion exchange resin having a trimethylammonium group as an exchange group, and chlorinated in the total exchange capacity of the anion exchange resin in an initial state. It is preferable that the ratio of the product ions is not more than the value obtained by the formula of R _Cl = 4 × C _Cl / CO ₂ ^0.53 . However, _RCl is the ratio (%) of chloride ions (eq / LR) to the total exchange capacity (eq / LR) of the anion exchange resin, and _CCl is the desired chloride ion concentration in the treated water ( ppb) and CO ₂ are CO ₂ concentrations (ppm) obtained by converting carbonic acid dissolved in the water to be treated into CO ₂ .

In the fuel cell water treatment apparatus, the anion exchange resin includes a strongly basic anion exchange resin having a dimethylethanolammonium group as an exchange group, and occupies the total exchange capacity of the anion exchange resin in an initial state. It is preferable that the ratio of chloride ions is not more than the value obtained by the formula of R _Cl = 1.3 × C _Cl / CO ₂ ^0.45 . However, _RCl is the ratio (%) of chloride ions (eq / LR) to the total exchange capacity (eq / LR) of the anion exchange resin, and _CCl is the desired chloride ion concentration in the treated water ( ppb) and CO ₂ are CO ₂ concentrations (ppm) obtained by converting carbonic acid dissolved in the water to be treated into CO ₂ .

  Moreover, in the water treatment apparatus for a fuel cell, it is preferable that the anion exchange resin in an initial state is a carbonate type by passing carbonate.

  In the water treatment apparatus for a fuel cell, it is preferable that 70 to 100% of the total exchange capacity of the anion exchange resin in the initial state is a carbonate type.

  Moreover, in the water treatment apparatus for the fuel cell, it is preferable that the water to be treated be passed through the anion exchange resin in a downward flow.

  Further, in the water treatment apparatus for a fuel cell, the treated water that passes through the anion exchange resin includes condensed water generated by a power generation reaction of the fuel cell, and the treated water is obtained by the anion exchange resin. After being processed, it is preferably reused in the fuel cell.

  ADVANTAGE OF THE INVENTION According to this invention, the water treatment apparatus for fuel cells which can reduce effectively the impurity ion in the water supplied to a fuel cell 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 diagram showing a relationship between _{R Cl} and _{C Cl} at various CO ₂ concentration in the water to be treated. It is a diagram showing a relationship between _{R Cl} and _{C Cl} at various CO ₂ concentration in the water to be treated.

  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 mainly a mixed bed resin of an anion exchange resin and a cation exchange resin. However, when a cartridge is also installed on the upstream side, an anion exchange resin or a cation exchange resin is also available. A single bed such as an ion exchange resin may be used. In addition, the water treatment apparatus 10 of the fuel cell may add a cartridge filled with activated carbon or the like in addition to the cartridge filled with the ion exchange resin.

  The fuel cell water treatment device 10 according to the present embodiment mainly reduces not only the removal of impurity ions in water supplied to the fuel cell 12 but also the elution from the water treatment device. Examples of water to be treated by the water treatment device 10 of the fuel cell include tap water (city water), pure water, and condensed water generated by the power generation reaction of the fuel cell 12.

  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 the impurity ion in water is removed by the water treatment apparatus 10 of a fuel cell.

  In the mixed bed resin of the anion exchange resin and the cation exchange resin of the present embodiment, the average particle size of the cation exchange resin is 0.2 mm or more and 80% or less of the average particle size of the anion exchange resin. . As explained above, cation exchange resin and anion exchange resin have different specific gravity (generally, cation exchange resin has higher specific gravity than anion exchange resin), so particle size outside the above range. If the cation exchange resin is used, the cation exchange resin with a higher specific gravity moves to the lower part and the anion exchange resin with a lower specific gravity moves to the upper part due to vibrations associated with the transportation, installation, operation, etc. of the water treatment device. The exchange resin is separated. When the mixed bed resin thus separated is operated at a high temperature and a low flow rate, for example, a cation component such as trimethylamine is eluted from the anion exchange resin, and an anion component such as polystyrene sulfonic acid is eluted from the cation exchange resin. There is a case. As a result, the TOC in the treated water increases. In addition, when the average particle size of the cation exchange resin is less than 0.2 mm, the pressure loss of the cartridge increases, so that the processing cost increases. When the average particle size of the anion exchange resin exceeds 80%, Thus, the difference in the terminal speed becomes large, and the cation exchange resin and the anion exchange resin are easily separated.

  Since the separation of both ion exchange resins due to vibration can be suppressed for the first time by using a mixed bed resin in which the particle size of the cation exchange resin is controlled as in this embodiment, the elution component from the anion exchange resin ( Cation components such as trimethylamine) are captured by the cation exchange resin, and components eluted from the cation exchange resin (anion components such as polystyrene sulfonic acid) are captured by the anion exchange resin. As a result, it is possible to reduce the TOC whose main component is the elution component, and to stably remove impurity ions.

  On the other hand, the volume of the anion exchange resin in the mixed bed resin of the present embodiment is preferably 1.5 to 5 times the volume of the cation exchange resin. When the volume ratio is converted into an exchange capacity, the total exchange capacity of the anion exchange resin is in a range of 0.85 to 3 times the total exchange capacity of the cation exchange resin. Here, if the volume of the anion exchange resin is less than 1.5 times the volume of the cation exchange resin, the proportion of the useless cation exchange resin increases and the anions in the water cannot be sufficiently removed. When the volume of the anion exchange resin is more than 5 times the volume of the cation exchange resin, the TOC component derived from the anion exchange resin is eluted without being captured, and the TOC in the treated water is eluted. May increase.

  Examples of impurity ions contained in water include carbonate ions, hydrogen carbonate ions, chloride ions, and sulfate ions. Fuel cell condensate contains a lot of carbonic acid, and removing a small amount of anions (chloride ions, sulfate ions, etc.) from condensate containing a large amount of carbonic acid is a common anion exchange resin. Then it is relatively difficult. In particular, the chloride ion is a monovalent anion, and the adsorption efficiency by the anion exchange resin is poor as compared with a polyvalent anion such as sulfate ion, so it is difficult to reduce the chloride ion in water.

  In the present embodiment, an anion exchange resin having a ratio of chloride ions in the total exchange capacity of the anion exchange resin in the initial state is preferably 10% or less, more preferably 1% or less. This makes it possible to effectively reduce chloride ions in water containing a large amount of carbonic acid. When the ratio of chloride ions in the total exchange capacity of the anion exchange resin in the initial state exceeds 10%, the anion exchange resin absorbs impurity ions such as carbonate ions contained in the water instead of chloride ions. Is easily released to the treated water side, and it becomes difficult to effectively reduce chloride ions in the treated water.

When the anion exchange resin includes a strongly basic anion exchange resin having a trimethylammonium group as an exchange group, the ratio of chloride ions to the total exchange capacity of the anion exchange resin in the initial state is expressed by the following formula (1 ) Or less is preferably obtained. Thereby, the ratio which discharge | releases a chloride ion to the treated water side in the treated water containing a large amount of carbonic acid falls, and the chloride ion in treated water can be reduced more effectively.
R _Cl = 4 × C _Cl / CO ₂ ^0.53 (1)
R _Cl : Ratio of chloride ion (eq / LR) to the total exchange capacity (eq / LR) of the anion exchange resin (%)
C _Cl : Desired chloride ion concentration in treated water (ppb)
CO ₂ : CO ₂ concentration (ppm) obtained by converting carbonate ions and hydrogen carbonate ions dissolved in the water to be treated into CO ₂

Further, when the anion exchange resin includes a strongly basic anion exchange resin having a dimethylethanolammonium group as an exchange group, the ratio of chloride ions in the total exchange capacity of the anion exchange resin in the initial state is expressed by the following formula: It is preferable that it is below the value calculated | required by (2). Thereby, the ratio which discharge | releases a chloride ion to the treated water side falls, and the chloride ion in treated water can be reduced more effectively.
R _Cl = 1.3 × C _Cl / CO ₂ ^0.45 (2)
R _Cl : Ratio of chloride ion (eq / LR) to the total exchange capacity (eq / LR) of the anion exchange resin (%)
C _Cl : Desired chloride ion concentration in treated water (ppb)
CO _2: CO ₂ concentration of the carbon dioxide which is dissolved in the water to be treated was converted to CO ₂ (ppm)

The above equation (1) is calculated from FIG. 2 showing the relationship between R _Cl and C _Cl at various CO ₂ concentrations in the water to be treated. The above equation (2) is calculated from FIG. 3 showing the relationship between R _Cl and C _Cl at various CO ₂ concentrations in the water to be treated. As can be seen from the above equation, when the desired chloride ion concentration in the treated water is small or the CO ₂ concentration dissolved in the treated water is large, it accounts for the total exchange capacity of the anion exchange resin in the initial state. It is necessary to reduce the ratio of chloride ions.

  Further, anion exchange resins used in water treatment devices for fuel cells have demands for heat resistance, downsizing, etc. in addition to reducing chloride ions. For example, Japanese Patent Application Laid-Open No. 11-204123 discloses an example in which an anion exchange resin having a plurality of hydrocarbon groups is used to improve heat resistance. The publication discloses an example of optimizing the amount of cation exchange resin filled in the mixed bed cartridge in order to reduce the size of the apparatus. Therefore, in the present embodiment, it is preferable to use carbonates such as ammonium bicarbonate that are passed through an anion exchange resin and converted to a carbonate type as an anion exchange resin in an initial state. However, since carbonic acid type anion exchange resin cannot remove carbonic acid, decarbonation (degassing membrane, decarbonation tower by air contact, etc.) can be performed later if carbonic acid removal is necessary. desirable. The carbonate type anion exchange resin has a small resin volume even with the same exchange capacity as compared with the anion exchange resin such as OH type. That is, the resin volume is reduced by replacing the OH type anion exchange resin with the carbonic acid type. For this reason, the apparatus can be miniaturized. Carbonic acid type anion exchange resins have higher heat resistance than OH type anion exchange resins. Therefore, even when treated water (for example, 40 to 80 ° C.) having a relatively high temperature, such as condensed water of a fuel cell, is processed, decomposition of the ion exchange resin due to heat is suppressed, and a decrease in ion exchange capacity is suppressed. can do.

  In the carbonate type anion exchange resin of the present embodiment, the proportion of chloride ions in the total exchange capacity of the anion exchange resin in the initial state is 10% or less, and the total exchange capacity of the anion exchange resin in the initial state is The proportion of carbonate ions occupied is preferably 70% or more, more preferably 90% or more, and even more preferably 100%. The carbonate type mentioned here includes both carbonate type and bicarbonate type. In the case of the carbonate type, it is preferable to substitute with bicarbonate (bicarbonate) instead of carbonate. This is because bicarbonate ions are more stable than carbonate ions under the fuel cell conditions.

  In the water treatment apparatus 10 of the fuel cell according to the present embodiment, it is preferable that water to be treated (for example, tap water, condensed water, etc.) is passed through the anion exchange resin described above in a downward flow. The anion exchange resin filled in the cartridge is consolidated by the downward flow of the water to be treated. As a result, the water to be treated can flow uniformly in the resin and improve the treatment performance.

As described above, the water treatment device 10 of the fuel cell according to the present embodiment reduces the eluted component (TOC) from the water treatment device 10 of the fuel cell into the water, and the concentration of impurity ions, particularly chloride ions, in the water. The treated water (pure water) with reduced water is supplied from the treated water line 22 to the fuel cell 12. Here, the fuel cell 12 is a solid oxide fuel cell, and in this example, the supplied water reforms city gas or the like into carbon monoxide (CO) and hydrogen gas (H ₂ ). Used for

  In the water treatment apparatus 10 for a fuel cell according to the present embodiment, the cation exchange resin and the anion exchange resin are not separated regardless of the use state, so that the eluted components (TOC) from these ion exchange resins are reduced. Accordingly, it is possible to suppress an increase in water conductivity due to the elution component of the ion exchange resin. Moreover, the production | generation of the ammonium ion, nitrate ion, nitrite ion, and sulfate ion which uses these elution components as a production source is suppressed. Furthermore, since a resin in which chloride ions in the ion exchange resin are appropriately managed is used, even water containing a large amount of carbonic acid, such as condensed water discharged from a solid oxide fuel cell, A small amount of chloride ions present in the water can be effectively removed. Therefore, the condensed water generated by the power generation reaction of the solid oxide fuel cell is processed by the water treatment device 10 of the fuel cell of the present embodiment, and the treated water is supplied to the solid oxide fuel cell and reused. However, stable fuel cell operation is possible over the long term. Further, when the condensed water is circulated and used, tap water or pure water may be supplied at the initial stage of operation of the fuel cell. When the condensed water is circulated and used, it is preferable to discharge the gas contained in the condensed water to the atmosphere, then treat it with the water treatment device 10 and supply it to the fuel cell.

  Note that SUS304, which is one of the general-purpose materials, is known to cause stress corrosion cracking depending on conditions even in the case of ppm level of chloride ions. It is necessary to reduce the chloride ion in water to 100 ppb or less, preferably 50 ppb or less, more preferably 10 ppb or less.

  In the solid oxide fuel cell, fuel gas (for example, city gas) and air (containing oxygen) are supplied to the (solid oxide type) fuel cell 12 from the fuel supply line 24 and the air supply line 26, respectively. Hydrogen gas or carbon monoxide obtained by the fuel reforming reaction reacts with oxygen to generate power. In such a solid oxide fuel cell, since power generation is performed at a high temperature of 600 to 1000 ° C., for example, exhaust water from the heat exchanger 28 is exchanged with tap water to supply hot water. preferable.

  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.

Example 1
An anion exchange resin having an average particle size of 0.7 mm (true density 1080 kg / m ³ ) and a cation exchange resin having an average particle size of 0.5 mm (true density 1140 kg / m ³ ) in a volume ratio of 3: 1 (= anion) A mixed bed resin cartridge (diameter: 40 mm × height: 200 mm) filled at a ratio of exchange resin: cation exchange resin) was prepared. This was shaken for 24 hours. Pure water was passed through the cartridge after shaking at 10 mL / min, and the TOC of the treated water was measured. Table 1 summarizes the presence or absence of the ion exchange resin after shaking and the TOC concentration.

(Comparative Example 1)
In Comparative Example 1, an anion exchange resin having an average particle size of 0.7 mm (true density 1080 kg / m ³ ) and a cation exchange resin having an average particle size of 0.7 mm (true density 1140 kg / m ³ ) were used. Were tested under the same conditions as in Example 1. Table 1 summarizes the presence or absence of the ion exchange resin after shaking and the TOC concentration.

  As can be seen from Table 1, in Example 1, the separation of the anion exchange resin and the cation exchange resin was not confirmed even when visually confirmed after shaking for 24 hours, and the TOC of the treated water after passing pure water. Was 0.1 ppm or less. In contrast, in Comparative Example 1, after shaking for 24 hours, it was confirmed that about 80% of the cation exchange resin was collected and separated at the bottom of the cartridge. In this state, the TOC in the treated water after passing pure water was 0.5 ppm.

(Example 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 250 ppm. As a water treatment apparatus, a mixed bed resin cartridge (diameter: 40 mm × height 200 mm) filled with 30 mL of an anion exchange resin having an average particle diameter of 0.7 mm and 10 mL of a cation exchange resin having an average particle diameter of 0.5 mm. Was used. The apparatus shown in FIG. 1 was supplied with 10 mL / min of condensed water (60 ° C.) of the fuel cell. Table 2 summarizes the TOC concentration of treated water after 24 hours of operation.

(Comparative Examples 2 and 3)
As Comparative Example 2, a cartridge filled only with 40 mL of anion exchange resin was used, and as Comparative Example 3, a cartridge filled only with 40 mL of cation exchange resin (diameter: 40 mm × height 200 mm) was used. The test was performed under the same conditions as in Example 2. Table 2 summarizes the TOC concentration of treated water after 24 hours of operation.

  As can be seen from Table 2, Example 2 in which the ratio of the anion exchange resin to the cation exchange resin is appropriate is Comparative Example 2 in which only the anion exchange resin is filled, and only the cation exchange resin is filled. As compared with Comparative Example 3, it was found that TOC can be kept lower. In Comparative Example 2 in which only the anion exchange resin was filled, trimethylamine considered to be derived from the functional group of the anion exchange resin was detected from the treated water. Moreover, in the comparative example 3 filled only with the cation exchange resin, the polystyrene sulfonic acid considered to be derived from the functional group of the cation exchange resin was detected from the treated water.

  From the results of Examples 1 and 2 above, if the ratio of the anion exchange resin to the cation exchange resin is mixed within an appropriate range, even if vibration during transportation of the resin cartridge or vibration after installation is applied, the Separation of the ion exchange resin and the anion exchange resin is suppressed. As a result, elution of the TOC component derived from the ion exchange resin can be suppressed, and high-purity water can be supplied.

(Examples 3 and 4)
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 250 ppm, and the chloride ion concentration was about 150 ppb. As the ion exchange resin filled in the cartridge, a mixed bed resin of 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 used. The anion exchange resin of Example 3 was obtained by passing 1500 mL of a 7% NaOH aqueous solution through a chlorine-type strongly basic anion exchange resin (Rohm and Haas, Amberjet 4002C1) to convert it into an OH type, The ratio of chloride ions to the total exchange capacity of the ion exchange resin (hereinafter sometimes simply referred to as R _Cl ) is 1% or less. The anion exchange resin of Example 4 is a mixture of the anion exchange resin of Example 3 and an anion exchange resin that has not been converted to OH type, so that _RCl is 10%. The cation exchange resin of Examples 3 and 4 is amber jet 1024H (manufactured by Rohm and Haas) which is a hydrogen type.

  In both Examples 3 and 4, the water to be treated was passed through the ion exchange resin in a downward flow. Then, after 24 hours of operation, the treated water treated with the ion exchange resin was sampled and the chloride ion concentration was measured. The results are summarized in Table 3.

(Comparative Example 4)
Comparative Example 4 was the same as Example 3 except that the anion exchange resin used had an _RCl of 20%.

As can be seen from Table 3, it was possible to reduce the chloride ion concentration in Example 4 using R _Cl 10% anion exchange resin to less 50 ppb. Further, in Example 3 using an anion exchange resin having an _RCl of 1% or less, the chloride ion concentration could be reduced to less than 10 ppb, and the chloride ion removal performance higher than that in Example 4 was exhibited. On the other hand, in Comparative Example 4 R _Cl was used 20% of the anion-exchange resin, the chloride ion concentration is 110Ppb, could not be adequately remove chloride ions.

If the CO ₂ concentration of treated water is 250 ppm and the chloride ion concentration of treated water is 50 ppb in the formula of R _Cl = 4 × C _Cl / CO ₂ ^0.53 , R _Cl becomes 10.7%. That is, in order to treat the water to be treated having a CO ₂ concentration of 250 ppm so that the chloride ion concentration in the treated water is 50 ppb or less, the ratio of chloride ions to the total exchange capacity of the anion exchange resin is 10. It is necessary to make it 7% or less. And the said Example 3, 4 is satisfying that it is below the value computed from said formula. If the chloride ion concentration in the treated water can be reduced to 50 ppb or less, the fuel cell can be stably operated over a long period of time.

(Examples 5 and 6)
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 250 ppm, and the chloride ion concentration was about 150 ppb. As the ion exchange resin filled in the cartridge, a mixed bed resin of 30 mL of strongly basic anion exchange resin having dimethylethanolammonium group as an exchange group and 10 mL of strongly acidic cation exchange resin was used. The anion exchange resin of Example 5 was passed through 1500 mL of a 7% NaOH aqueous solution through a strong basic anion exchange resin of the chlorine type (Amberlite IRA410Cl, manufactured by Rohm and Haas, Inc.) to convert it into an OH type. _Cl is 1% or less. The anion exchange resin of Example 6 is a mixture of the anion exchange resin of Example 5 and an anion exchange resin that has not been converted to OH type to have _RCl of 5%. The cation exchange resin of Examples 5 and 6 is H-type Amberjet 1024H (manufactured by Rohm and Haas).

  In both Examples 5 and 6, the water to be treated was passed through the ion exchange resin in a downward flow. Then, after 24 hours of operation, the treated water treated with the ion exchange resin was sampled and the chloride ion concentration was measured. The results are summarized in Table 4.

(Comparative Example 5)
Comparative Example 5 was the same as Example 5 except that the anion exchange resin used had an _RCl of 20%.

As can be seen from Table 4, it was possible to reduce the chloride ion concentration in Example 6 using R _Cl 5% anion exchange resin to less 50 ppb. In Example 5 using an anion exchange resin having an R _Cl content of 1% or less, the chloride ion concentration could be reduced to less than 10 ppb, indicating higher chloride ion removal performance than Example 6. On the other hand, in Comparative Example 5 using an anion exchange resin having an R _Cl content of 20%, the chloride ion concentration was 210 ppb, and the chloride ions could hardly be removed.

If the CO ₂ concentration of the treated water is 250 ppm and the chloride ion concentration of 50 ppb in the treated water is applied to the formula of R _Cl = 1.3 × C _Cl / CO ₂ ^0.45 , R _Cl becomes 5.4%. That is, in order to treat the water to be treated having a CO ₂ concentration of 250 ppm so that the chloride ion concentration in the treated water is 50 ppb or less, the ratio of chloride ions to the total exchange capacity of the anion exchange resin is 5. It must be 4% or less. And the said Example 5, 6 is satisfying that it is below the value computed from said formula.

(Examples 7 and 8)
The apparatus shown in FIG. 1 was used to treat the condensed water discharged from the solid oxide fuel cell. As the ion exchange resin filled in the cartridge, a strongly basic anion exchange resin having a trimethylammonium group equivalent to 0.13 eq as an exchange group was used. The anion exchange resins of Examples 7 and 8 were OH-type strongly basic anion exchange resin (Rohm and Haas, Amberjet 4002OH) and ammonium bicarbonate (ammonium bicarbonate (NH ₄ ) HCO ₃ ) (1 4L), and the ratio of chloride ions to the total exchange capacity of the anion exchange resin (R _Cl ) is 1% or less and the ratio of carbonate ions (hereinafter sometimes simply referred to as R-carbonic acid). 90% or more and 70%.

  Condensed water (about 60 ° C.) generated in a solid oxide fuel cell having a power generation amount of 1 kW was supplied to the water treatment apparatuses of Examples 7 and 8 and operated for 24 hours. The water to be treated was passed through the ion exchange resin in a downward flow. Table 5 summarizes the results of measuring the volume of the ion exchange resins of Examples 7 and 8 and the TOC concentration in the treated water.

(Comparative Example 6)
Comparative Example 6 was the same as Example 7 except that the R-carbonic acid of the anion exchange resin used was less than 1%.

  As can be seen from Table 5, by making the ion exchange resin into a carbonate type as in Examples 7 and 8, the resin volume can be reduced without impairing the ion exchange capacity compared to the OH type ion exchange resin of Comparative Example 6. I was able to. In particular, in Example 7 in which R-carbonic acid was 90% or more, the resin volume was reduced by 20% compared to Comparative Example 6. Further, even when the carbonic acid ion exchange resin of Examples 7 and 8 was treated by passing condensed water at 60 ° C., the TOC in the treated water was 0.1 ppm or less, and the resin was decomposed by heat. It was found to be suppressed. On the other hand, when the treatment was conducted by passing 60 ° C. condensed water through the OH ion exchange resin of Comparative Example 6, 0.5 ppm of TOC was detected in the treated water, and the resin due to heat was decomposed. It is considered a thing.

  Thus, by making the anion exchange resin in the initial state carbonic acid type in advance, the installation space of the apparatus can be reduced, decomposition of the resin due to heat can be suppressed, and elution of TOC can be reduced.

Example 9
Example 9 was the same as Example 3 except that the flow direction of the water to be treated to the ion exchange resin was an upward flow. And the treated water processed with the ion exchange resin was sampled, and the chloride ion concentration was measured. The results are summarized in Table 6 (for comparison, the results of Example 3 are also listed in Table 6).

  In Example 9 in which the direction of water to be treated was upward, the resin was not consolidated and a slight flow was observed. Therefore, a short circuit flow occurred in Example 9, and the chloride ion concentration in the treated water increased slightly compared to Example 3 which was a downward flow. Therefore, it is preferable to perform the water treatment in a downward flow as in the third embodiment.

  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 (7)

A water treatment device for a fuel cell using an ion exchange resin, wherein the ion exchange resin includes a mixed bed resin of a cation exchange resin and an anion exchange resin,
An average particle size of the cation exchange resin is 0.2 mm or more and 80% or less of an average particle size of the anion exchange resin.   The water treatment apparatus for a fuel cell according to claim 1, wherein the volume of the anion exchange resin is 1.5 to 5 times the volume of the cation exchange resin. apparatus. The water treatment apparatus for a fuel cell according to claim 1 or 2, wherein a ratio of chloride ions to a total exchange capacity of the anion exchange resin in an initial state is a concentration of CO ₂ dissolved in the water to be treated. A fuel cell water treatment apparatus, which is set to be inversely proportional to each other and proportional to a desired chlorine concentration in the treated water. A water treatment device for a fuel cell according to claim 3 Symbol placement, the anion exchange resin comprises a strong basic anion exchange resin to exchange group trimethylammonium group, the anion exchange resin in the initial state all A water treatment apparatus for a fuel cell, characterized in that a ratio of chloride ions in the exchange capacity is not more than a value (R _Cl ) obtained by the following formula (1)
R _Cl = 4 × C _Cl / CO ₂ ^0.53 (1)
(Where R _Cl is the ratio (%) of chloride ions (eq / LR) to the total exchange capacity (eq / LR) of the anion exchange resin, and C _Cl is the desired chloride ion concentration in the treated water. (Ppb), CO ₂ is the CO ₂ concentration (ppm) dissolved in the water to be treated. A water treatment device for a fuel cell according to claim 3 Symbol placement, a water treatment device for a fuel cell using an anion exchange resin, the anion exchange resin to exchange groups dimethylethanolammonium groups strong bases The ratio of chloride ions to the total exchange capacity of the anion exchange resin in the initial state is not more than the value (R _Cl ) obtained by the following formula (2). Fuel cell water treatment device.
R _Cl = 1.3 × C _Cl / CO ₂ ^0.45 (2)
(Where R _Cl is the ratio (%) of chloride ions (eq / LR) to the total exchange capacity (eq / LR) of the anion exchange resin, and C _Cl is the desired chloride ion concentration in the treated water. (Ppb), CO ₂ is the CO ₂ concentration (ppm) dissolved in the water to be treated. The water treatment apparatus for a fuel cell according to any one of claims 1 to 5 , wherein the water to be treated is passed through the anion exchange resin in a downward flow. Water treatment equipment. The water treatment apparatus for a fuel cell according to any one of claims 1 to 6 , wherein the water to be treated that is passed through the anion exchange resin includes condensed water generated by a power generation reaction of the fuel cell. The water treatment apparatus for a fuel cell, wherein the water to be treated is treated with the anion exchange resin and then reused in the fuel cell.

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