JP3330483B2 - Condensate desalination equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condensate desalination apparatus, and more particularly to a condensate desalination apparatus for a BWR type nuclear power plant.

[0002]

2. Description of the Related Art Conventionally, a gel-type cation exchange resin has been used for condensate desalination in applications where a large exchange capacity and a high cladding removal performance are required and the regeneration frequency is not so high. In applications, macroporous cation exchange resins having high physical strength have been used. In addition, as the anion exchange resin used as a mixed bed with these cation exchange resins, the same type of resin as the cation exchange resin has been used. In other words, when the cation exchange resin is a gel type cation exchange resin, a gel type is used for the anion exchange resin. For example, in a condensate treatment in a BWR type nuclear power plant, this combination is generally used. Was.

[0003] Cation exchange resins are more easily oxidatively decomposed in an oxidizing atmosphere such as dissolved oxygen in water than anion exchange resins, and as a result, low-molecular-weight polystyrene sulfonic acid and the like formed by decomposition from the cation exchange resin. Eluted. In a mixed-bed column used in a condensate desalination apparatus, the eluate from the cation exchange resin contaminates the anion exchange resin, which is one of the factors that reduce its reactivity. When the reactivity of the anion exchange resin decreases, the effluent of the cation exchange resin flows into the boiler, reactor and steam generator without being trapped by the anion exchange resin in the condensate of the power plant and the treated water. Decomposes under high temperature to CO ₂ or SO ₄ ^2-
As a result, the amount of ions increases, and the inflow of seawater due to the leakage of the condenser causes a decrease in the treated water quality of the condensate desalination apparatus.

The amount of the organic substance eluted from the cation exchange resin is larger in the gel type cation exchange resin than in the macroporous type cation exchange resin, and the lower the degree of crosslinking, the larger the elution amount. There was a problem in using a gel-type cation exchange resin having a low degree of crosslinking. However, in recent years, the demand for the separation effect of cladding required for cooling water of nuclear power plants has become more sophisticated, and in order to respond to this, cation exchange resins with excellent cladding removal performance have been searched for. It has been found that gel-type cation exchange resins with a low degree of cross-linking are effective in removing cladding. Therefore, there has been a demand for the development of a new condensate desalination apparatus for using a gel-type cation exchange resin having a low degree of cross-linking without causing an increase in the amount of elution into treated water.

On the other hand, the anion exchange resin includes a gel type resin and a macroporous type resin, and the characteristics thereof are as follows. Gel-type resins, which are strongly basic anionic resins without macropores, generally have a volume-based ion exchange capacity (Volume) when compared to porous resins.
Capacity; Vol. Cap.) And the amount (rate) of adsorbing high molecular compounds such as fine particles and polystyrene sulfonic acid (hereinafter sometimes abbreviated as PSS) is small. That is, when the gel-type resin is used, the amount of trapped PSS (rate) is small,
Therefore, the PSS passes through, and the PSS causes sulfate ions and TOC. On the other hand, a strongly basic anionic resin having a macro pore called a porous resin generally has a lower ion exchange capacity on a volume basis as compared with a gel resin, and adsorbs fine particles and high molecular compounds well.
That is, when the macroporous resin is used, PSS is efficiently captured, and the amount (rate) of PSS captured is large. That is, Vol. Cap. Is high, but PSS cannot be efficiently adsorbed and removed.
SS can be efficiently adsorbed and removed.
Cap. Is low, Vol. Cap. Therefore, a method of efficiently adsorbing and removing PSS while keeping the PSS high has been desired.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a condensate desalination apparatus which has excellent cladding removal performance and a small amount of organic substances eluted from a mixed bed. An object is to provide a device useful for condensate treatment.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, by using a mixed bed composed of a gel type cation exchange resin and a macroporous type anion exchange resin, The inventors have found that the amount of organic substances eluted into the mixed-bed treated water can be reduced, and completed the present invention. That is, the present invention relates to a gel type cation exchange resin having a degree of crosslinking of 2.5 to 10%, and a macroporous type anion exchange resin.
The use of mixed bed consisting of providing condensate demineralizer according to claim. The present invention is suitable as a condensate demineralizer of a BWR nuclear power plant, and a gel-type cation exchange resin cross-linking degree of 2.5 to 10% by one embodiment thereof, the macroporous anion exchange resin characterized by using the composed mixed bed comprises a condensate demineralizer of a BWR nuclear power plant.

The degree of crosslinking of the gel type cation exchange resin is 10%
Below, preferably 8% or less, more preferably 6% or less, good cladding removal performance can be obtained. However, according to the apparatus of the present invention, good gel-type cation exchange resin can be used. The amount of organic substances eluted can be reduced while maintaining the clad removal performance. From the viewpoint of the physical strength of the resin, the degree of crosslinking is preferably 2.5% or more, and more preferably 4% or more. Further, in order to maintain the performance of removing the clad, the degree of crosslinking of the gel-type cation exchange resin is preferably 10% or less.

In an ion exchange resin, the degree of cross-linking and the water holding capacity are closely related, and generally, the lower the degree of cross-linking, the greater the water holding capacity. Therefore, the gel-type cation exchange resin used in the present invention can be defined by the water holding capacity. That is, recovery of the present invention is water held capacity from 44 to 73%, preferably characterized by the use and the gel-type cation exchange resin is 44 to 70%, a mixed bed consisting of macroporous anion-exchange resin A water desalination apparatus is provided, and as one embodiment, a mixed bed comprising a gel type cation exchange resin having a water retention capacity of 44 to 73%, preferably 44 to 70%, and a macroporous anion exchange resin. BWR characterized by using
Includes condensate and desalination equipment for nuclear power plants.

As in the case of the degree of cross-linking, when the water-retaining capacity of the gel-type cation exchange resin is at least 44%, preferably at least 50%, good clad removal performance can be obtained. According to the salt apparatus, the amount of organic substances eluted can be reduced while maintaining good clad removal performance, regardless of which gel-type cation exchange resin is used. The water holding capacity is about 73%, which is the upper limit of the gel type cation exchange resin that can be actually used. If the water holding capacity is more than this, the physical strength is too weak and it is difficult to actually use it.

As the gel type cation exchange resin used in the present invention, known ones can be used. For example, manufactured by copolymerizing aromatic monovinyl monomers such as styrene, vinyl toluene, vinyl xylene, ethyl styrene, and chlorostyrene with aromatic polyvinyl monomers such as divinyl benzene and divinyl toluene, and introducing a cation exchange group into the copolymer. it can. As the polyvinyl monomer, an aromatic polyvinyl monomer and an ester-based polyvinyl monomer can be used in combination, and a gel-type cation exchange resin derived from such a copolymer is more preferable. As the ester-based polyvinyl monomer, for example, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, and the like,
Acrylates corresponding to these can be used alone or as a mixture.

The degree of crosslinking refers to the degree of crosslinking by the above-mentioned polyvinyl monomer, and refers to the mass ratio (%) of divinylbenzene to all vinyl monomers. However, in the case of a resin in which the above-mentioned aromatic polyvinyl monomer and ester-based polyvinyl monomer are used in combination, the degree of crosslinking cannot be defined by the above definition of the degree of crosslinking. In that case,
Based on the water holding capacity, a suitable gel type cation exchange resin can be selected and determined. What is water retention capacity?
It refers to the water content when the water content in the pores of the resin is adjusted to a saturated equilibrium state, and the measurement method is described in detail in Examples below.

The macroporous anion exchange resin in the present invention is also called a giant network ion exchange resin.
R type (macro reticular) and MP type (macro porou)
s). The internal structure of a normal gel-type ion exchange resin has a network structure (microporosity) determined by the degree of molecular cross-linking, whereas the MR-type ion exchange resin has a distinct physical pore (macroporosity). And microporosity. This can be produced by copolymerizing styrene-divinylbenzene and changing the polymerization method when introducing an ion exchange group. The macroporous ion exchange resin has a slightly small ion exchange capacity, but has excellent performance in removing organic substances. In addition, it has high physical strength and can be highly purified, and is chemically stable. Known and commercially available macroporous ion exchange resins having a diameter of 100 to 1000 μm can be used, and both strong basic resins and weak basic resins can be used. Commercially available macroporous ion exchange resins suitably used in the present invention include, for example, Amberlite (IRA-900, IRA-9, manufactured by Rohm and Haas Company).
04, IRA-938, IRA-911, IRA-9
3), Mitsubishi Chemical Diaion (PK308, PA3
16, PA416, WA30).

In the present invention, the ratio of the gel cation exchange resin to the macroporous anion exchange resin is as follows: gel cation exchange resin: macroporous anion exchange resin = 1: 2 to 3: 1 (volume ratio) Is preferred. Also,
The gel type cation exchange resin is usually used in the H type, and the macroporous type anion exchange resin is used in the OH type.

The present inventors have reported in Vol. Cap. It has been found that a mixture of a gel-type resin and a porous-type resin may be used in order to efficiently adsorb and remove PSS while maintaining a high PSS. That is, in the present invention, a mixture of a macroporous anion exchange resin and a gel anion exchange resin can be used. Accordingly, the present invention provides a mixed bed comprising a gel type cation exchange resin, a macroporous type anion exchange resin, and a gel type anion exchange resin having a degree of crosslinking of 2.5 to 10%, preferably 4 to 10%. A condensate desalination apparatus characterized in that it is used, and a gel type cation exchange resin having a water retention capacity of 44 to 73%, preferably 44 to 70%, a macroporous anion exchange resin, and a gel type there is provided also a condensate demineralizer, which comprises using a mixed bed consisting of an anion exchange resin.

The preferable volume ratio of the MR type anion exchange resin / gel type anion exchange resin is based on the total volume of the MR type anion exchange resin and the gel type anion exchange resin.
MR type anion exchange resin is 5% or more, more preferably 4% or more.
0% or more. The ratio of the gel type cation exchange resin to the total of the macroporous type anion exchange resin and the gel type anion exchange resin is as follows: cation exchange resin: anion exchange resin = 1: 2 to 3: 1 (volume ratio) Is preferred. Gel type anion exchange resins are also usually used in OH type.

The gel type anion exchange resin refers to an anion exchange resin which does not have macroporosity but has only a stitch structure (microporosity) which is determined by the degree of molecular crosslinking. Known gel-type anion exchange resins used in the present invention can be used. For example, the gel-type anion exchange resin, like the gel-type cation exchange resin described above, styrene, vinyl toluene, vinyl xylene,
It can be produced by copolymerizing an aromatic monovinyl monomer such as ethylstyrene and chlorostyrene with an aromatic polyvinyl monomer such as divinylbenzene and divinyltoluene, and introducing an anion exchange group into the copolymer.

The present invention can be used for condensate treatment in the fields of general industrial boilers, thermal power plants, nuclear power plants, paper dryers, etc., and is particularly useful for condensate treatment of thermal power plants and nuclear power plants. In particular, it is useful as an apparatus for treating water in a condensate circulation system operated by a combined water treatment method or a neutral water treatment method in a power plant. More preferably, desalination treatment of condensed water operated by the neutral water treatment method of the BWR type nuclear power plant, desalination treatment of secondary system water which is condensed water of the PWR type nuclear power plant, and thermal power plant It is applied to the desalination treatment of condensate and the like, and is effective in removing the clad together with the removal of the impurity ions.
The condensate desalination apparatus of the present invention is characterized by the combination of the ion exchange resins used as described above, and this point is different from the conventional condensate desalination apparatus, but the other structures are the same as those of the conventional condensate desalination apparatus. Since it is almost the same as the water desalination apparatus, detailed description of the structure of the apparatus will be omitted.

Example Reference Example 1 A cation exchange resin and an anion exchange resin were regenerated into H-form and OH-form by a conventional method, and sufficiently washed with ultrapure water. Thereafter, each ion exchange resin is immersed in ultrapure water at a volume ratio of resin / ultrapure water = 1/1, left under heating at 60 ° C. for 24 hours, and the TOC of the supernatant water after immersion for 24 hours is measured. did. The following were used as samples. Sample A: Gel-type cation exchange resin having a degree of crosslinking of 8% (Amberlite IR-120B) Sample B: Gel-type cation exchange resin having a degree of crosslinking of 6% (Amberlite XT-1004) Sample C: Macroporous anion Exchange resin (Amberlite IRA-900CP) Sample D: Gel type anion exchange resin (Amberlite IRA-400T) Both the above resin and the ion exchange resin used in the following examples are sold by Organo Corporation. Is what it is. The results are shown in FIG. The TOC displayed is the increase in TOC due to the immersion of the ion-exchange resin after subtracting the TOC of the ultrapure water.
The same applies to and 2. In FIG. 1, reference characters A to D on the horizontal axis respectively correspond to the sample names of the ion exchange resins.

Example 1 A cation-exchange resin and an anion-exchange resin were regenerated into H-form and OH-form by a conventional method, washed with ultrapure water, and then mixed with the cation-exchange resin and anion-exchange resin by a volume ratio of 1 /. 1 to prepare a mixed resin. The mixed resin was immersed in ultrapure water at a volume ratio of resin / ultrapure water = 1/1, left under heating at 60 ° C. for 24 hours, and TOC of the supernatant water after immersion for 24 hours was measured. The samples of the gel-type cation exchange resin used are as follows. Sample A: Amberlite IR-120B (crosslinking degree 8%, moisture retention capacity 47.0%) Sample B: Amberlite IR-120BN (crosslinking degree 8%, moisture retention capacity 45.3%) Sample C: Amberlite XT -1004 (crosslinking degree 6%, water holding capacity 53.8%) The above sample was mixed with gel type anion exchange resin (Amberlite IRA-400T) or macroporous type anion exchange resin (Amberlite IRA-900CP). Floor, and in each case the T
OC was measured. The results are shown in FIG. 2, where the hatched one is the result of a mixed bed of the gel-type cation exchange resin and the gel-type anion exchange resin, and the other is the result of the gel-type cation exchange resin and the macroporous-type anion exchange resin. The result is a mixed bed with an ion exchange resin. In FIG. 2, the symbols A, B, C on the horizontal axis correspond to the sample names of the cation exchange resin.
Comparing the gel type anion exchange resin and the macroporous type anion exchange resin alone, as shown in FIG. 1, the gel type anion exchange resin has a smaller TOC elution amount despite the smaller TOC elution amount. When mixed with an ion exchange resin, unexpectedly, the macroporous anion exchange resin has a smaller TOC elution amount than the ion exchange resin.

In this example and the following examples, the value of the water retention capacity was measured by the following method for a gel type strongly acidic cation exchange resin having an ionic form as a reference form (sodium form). Value. (A) Normal form (sodium form) with water in equilibrium
A sample resin is prepared. (B) Weigh about 5 g of the sample resin prepared in (a) up to 1 mg into two flat weighing bottles each having a constant weight. (C) This is placed in a drying container which has been previously adjusted to 110 ± 5 ° C., and dried for 24 hours. (D) Allow to cool in a desiccator for about 30 minutes. (E) Next, the weight of the weighing bottle is measured by closing the lid of the weighing bottle. Calculate the water holding capacity (%). M ₁ = a / W × 100 where M ₁ : water holding capacity (%) W: resin in which water is in an equilibrium state (g) The weight of the resin in which the water is in an equilibrium state and the resin after drying are the same. The test is repeated for each of the two resins, and when the two results fluctuate by 0.5% or more, the test is repeated, and when the results match within 0.5%, the average value of the two is shown as the test result.

Example 2 Gel-type cation exchange resin regenerated to H-type (Amberlite XT-1004), gel-type anion-exchange resin regenerated to OH-type (Amberlite IRA-400T) and macroporous anion Exchange resin (Amberlite I)
RA-900CP) was mixed at a volume ratio of 1/1, and the mixed resin was packed in an acrylic column having an inner diameter of 20 mm and a height of 800 mm, and ultrapure water at 25 ° C. was passed at a linear flow rate of 20 meters per hour. Measure the TOC of the column outlet water at this time,
The results are shown in FIG. As is apparent from FIG. 3, in the mixed bed of the gel-type cation exchange resin and the macroporous-type anion exchange resin, the mixture of the gel-type cation exchange resin and the gel-type anion exchange resin has been used for a long time from the beginning of use. Outlet water with a significantly lower TOC concentration than in the bed was obtained.

Reference Example 2 Gel type anion exchange resin (IRA-400T) and macroporous type anion exchange resin (IRA-900C)
P), a standard substance (molecular weight: 10,000) of polystyrenesulfonic acid (PSS), which is a typical decomposition product eluted from the cation exchange resin, is adsorbed in a predetermined amount, and the mass transfer coefficient (MTC) of the resin after adsorption is adsorbed. ) Was measured to examine the relationship between the amount of PSS adsorbed and the dynamic performance of the anion exchange resin. FIG. 4 shows the results of the amount of PSS adsorbed on the anion exchange resin and the dynamic performance of the anion exchange resin. The PSS adsorption amount on the horizontal axis in FIG. 4 is the amount of PSS remaining in the resin after the PSS was once adsorbed on the anion exchange resin and then regenerated using an aqueous sodium hydroxide solution. is there. FIG. 4 shows that the macroporous anion-exchange resin has stronger stain resistance than the gel-type anion-exchange resin, and has less decrease in reactivity.

Example 3 Using a mixed bed of a gel type anion exchange resin (IRA-400T) and an MR type anion exchange resin, and using a mixed resin of various ratios, the adsorption amount and adsorption rate of PSS according to Reference Example 2. Was measured. As a PSS sample, Poly NaSS 5 (molecular weight: 50,000) manufactured by Tosoh Corporation was used. PSS adsorption condition: 100 ml of H-type PSS aqueous solution (about 0.1%) was added to each 50 ml of OH-type strong basic anion exchange resin.
and shaken at 40 ° C. for 16 hours. 0.45 μm
Was filtered. Resin preparation conditions: 100 ml of standard type (Cl type) resin
After passing 2 liters of an 8% NaOH aqueous solution over 5 hours, 2 liters of ultrapure water was passed for 1 hour. PSS preparation conditions: Na type (standard type) polystyrene sulfonic acid (20%) 20 g, resin height 50 cm, resin amount 20
The mixture was passed through 0 ml of the strongly acidic cation exchange resin of the H type over 1 hour to obtain the H type. The analysis was performed by HPLC. Table 1 shows the results.

[0025]

[Table 1]

In Table 1, the “actual adsorption rate” is a value obtained by dividing the amount of adsorption of PSS adsorbed on the anion exchange resin by the load of PSS and multiplying the result by 100, and is expressed in%. It is expressed by an equation. Actual adsorption ratio (%) = [PSS adsorption amount (mg) / PSS load amount (mg)] × 100 “Simple average adsorption ratio” is obtained by comparing the gel type anion exchange resin with the MR.
The adsorption rate predicted based on the mixing ratio when the type anion exchange resin is mixed, the actual adsorption rate of the gel type anion exchange resin is A (%), and the actual adsorption rate of the MR type anion exchange resin Rate as B (%), gel type anion exchange resin and M
Assuming that the respective volume fractions in the mixture of the R-type anion exchange resin are V1 and V2, they are represented by the following equations. Simple average adsorption rate (%) = A × V1 + B × V2 From the comparison between the simple average adsorption rate and the actual adsorption rate of the mixture, it can be seen that the mixing rate of the MR type strong basic anion exchange resin significantly improves the mixing rate. I understand.

Example 4 In this example, PSS having a molecular weight of 400,000 to 600,000 was used, and the PSS adsorption rate was measured in the same manner as in Example 3.
The results are as shown in Table 2.

[0028]

[Table 2]

[0029]

According to the present invention, a combination of a gel type cation exchange resin having a specific degree of crosslinking or a specific water holding capacity and a macroporous type anion exchange resin according to the present invention provides excellent clad removal performance and mixing. It is possible to obtain a condensate desalination apparatus capable of reducing the amount of organic substances eluted in the bed system and suppressing the decrease in the reactivity of the anion exchange resin.

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of Reference Example 1.

FIG. 2 is a diagram showing the results of Example 1.

FIG. 3 is a diagram showing the results of Example 2.

FIG. 4 is a diagram showing the results of Reference Example 2.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-101782 (JP, A) JP-A-2-131187 (JP, A) JP-A-61-254293 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C02F 1/42 B01J 47/00-47/14 G21C 19/30

Claims (6)

(57) [Claims] 1. A gel type cation exchange resin having a degree of crosslinking of 2.5 to 10%, and a macroporous type anion exchange resin.
A condensate desalination apparatus characterized by using a mixed bed consisting of: 2. The gel-type cation exchange resin has a degree of crosslinking of 4 to 4.
The condensate desalination apparatus according to claim 1, wherein the concentration is 10%. 3. A water held capacity and gel-type cation exchange resin is 44 to 73%, macroporous condensate demineralizer apparatus characterized by using a mixed bed consisting of an anion exchange resin. 4. The condensate desalination apparatus according to claim 3, wherein the gel type cation exchange resin has a water holding capacity of 44 to 70%. 5. The condensate desalination apparatus according to claim 1, wherein the mixed bed further contains a gel type anion exchange resin. 6. The mixed bed further contains a gel type anion exchange resin, and the macroporous type anion exchange resin contains at least 5% of the total volume of the macroporous type anion exchange resin and the gel type anion exchange resin. The condensate desalination apparatus according to any one of claims 1 to 4.