JPH0445233B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a mixed-bed excessive desalination method for treating secondary system water of a PWR type nuclear power plant, and in particular, the present invention relates to a method for increasing water content compared to conventional products. This invention relates to a mixed-bed excessive desalination method in which a cation exchange resin and an anion exchange resin are mixed.

[Conventional technology]

Conventionally, in PWR power plants, it is necessary to keep impurities in the water supply as low as possible, so the condensate that flows from the condenser to the steam generator (hereinafter referred to as SG) is purified using a condensate desalination tower. After being highly purified, it is used as a water supply.

This condensate demineralization tower is a so-called mixed bed demineralization tower packed with a mixture of anion exchange resin and cation exchange resin, and contains ionic components and suspended solid components (commonly known as cladding) in condensate. This method separates the condensate by ion exchange and adsorption to purify the condensate.

The conventional method of mixing a cation exchange resin and an anion exchange resin to form a mixed bed is to use a gel type cation exchange resin and a gel type anion exchange resin with a water content (45 to 55%). Conventionally, a method using a porous cation exchange resin and a porous anion exchange resin with a water content (45 to 55%) has been proposed.

[Problem to be solved by the invention]

Recently, in mixed-bed over-desalination technology, the separation effect of ion components and cruds from condensate water has been strengthened.
There is a tendency to maintain the integrity of the SG by reducing the amount of crud brought into the SG, and in the method using the granular ion exchange resin described above, the ability to capture crud is controlled by the affinity between the ion exchange resin and the crud. Therefore, the current ion exchange resins with low water content have a small separation effect on the current cladding, which is mainly relatively hydrophilic, and cannot sufficiently meet the demands for more sophisticated equipment.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a mixed-bed over-desalination method that has a large crud separation capacity in a condensate treatment operation.

[Means to solve the problem]

As a result of intensive research, the present inventors have discovered that the object of the present invention can be achieved by using an ion exchange resin with a higher water content than conventional products. This is the completed version.

That is, the present invention provides a method for excessive desalination using a mixed bed consisting of a granular or powdered cation exchange resin and an anion exchange resin when treating secondary system water of a PWR type nuclear power plant. A mixed bed is formed using a resin in which the water content of the ion exchange resin and/or anion exchange resin is increased (55 to 75%) compared to the standard value (45 to 55%) of conventional gel type resins, A mixed bed over-desalination method is characterized by enhanced ability to remove suspended impurities during secondary system water treatment in a PWR nuclear power plant.

Furthermore, the present invention provides a method for excessive desalination using a mixed bed consisting of a granular or powdered cation exchange resin and an anion exchange resin when treating secondary system water of a PWR type nuclear power plant. A resin in which a cation exchange resin with an increased water content (55-75%) than the standard value (45-55%) of conventional gel-type resins is laminated on the upper layer of the product's mixed bed of ion-exchange resin. There is also a mixed bed over-desalination method characterized by forming a bed and enhancing the ability to remove suspended impurities during secondary system water treatment in a PWR type nuclear power plant.

Next, the present invention will be explained in more detail while comparing it with the prior art.

Figure 1 is a graph showing the relationship between water content and crushing strength, with the water content of a strongly acidic cation exchange resin shown on the horizontal axis and the crushing strength of the resin on the vertical axis. As it increases, the crushing strength of the resin decreases, and this tendency is also seen in strongly basic anion exchange resins.

Figure 2 shows the water content of a strongly acidic cation exchange resin on the horizontal axis and the total exchange capacity on the vertical axis.
According to this, the total exchange capacity decreases as the water content increases. FIG. 3 shows the relationship between the water content and total exchange capacity of strongly basic anion exchange resins, and the same tendency as in FIG. 2 can be seen.

From the above, by increasing the water content of ion exchange resin, properties such as crushing strength and total exchange capacity tend to deteriorate. In the present invention, the water content of the cation exchange resin and anion exchange resin should be set at 55 to 75%, preferably 60 to 70%.
It is considered appropriate to keep it within the range of .

〔Example〕

Examples are described below, but the present invention is not limited to these examples.

Example 1 The water content of the cation exchange resin was varied and the crud separation effect was compared with a conventional over-desalination operation through a single-bed mini-column test and a mixed-bed actual length column test.

(Single-bed mini-column test) Test conditions Using the test equipment shown in Figure 4, raw water is injected into raw water inlet 1.
A test was conducted under the following test conditions through packed column 3.

Γ Resin specifications: Strongly acidic gel type cation exchange resin (H
Type) with water content of 47, 55, 61, or 70%. Γ Pressure-resistant column: Inner diameter 12 mm φ x 200 mm Γ Resin amount: Strongly acidic gel type cation exchange resin 15 ml Γ Resin layer height: 133 mm Γ Linear water flow rate: LV =108m/
h Γ Water flow period: Approximately 2 weeks for each test Test results The results of the single-bed mini-column test using only cation exchange resin are shown in Figure 5. Figure 5 is a graph showing the crud capture ratio when the horizontal axis represents the water content and the vertical axis represents the product with a 55% water content as 1. According to this graph, increasing the water content is more effective in separating the crud. It was confirmed that this improved.

(Mixed bed actual machine length column test) Test conditions The test was conducted using the test equipment shown in Figure 6. In FIG. 6, raw water introduced from the raw water inlet 1 is purified by a resin-filled column 3, passes through a main flow meter 4, and part of it enters a sampling line, which includes a filter 5, a flow meter 6, an integrated flow meter 7, It passes through a conductivity meter 8 and is discharged from a drain line 9. 2 is an inlet for pure water for cleaning.

The test was conducted under the following test conditions.

Γ Resin specifications: Strongly acidic gel type cation exchange resin (H
Type) with a water content of 47, 55, 61, and 70%, and a strong basic gel type anion exchange resin (OH type) with a conventional water content, used in a mixed bed state. Γ Resin amount: cation/anion Resin ratio = 1.66/1
Mix and fill the amount equivalent to 90cm bed height (approx. 2) with Figure 7 shows the results of a mixed-bed actual length column test using a mixed bed with varying resin water content, which shows that increasing the water content of the cation exchange resin improves the cladding separation effect (DF). It was confirmed that the value) was improved. In addition, Figure 7 shows the water content and DF when the water content of the cation exchange resin is changed.
(here, DF value represents inlet crud concentration/outlet crud concentration (ppb)).

The above test results were obtained by changing the water content of the cation exchange resin, and it was found that the crud separation effect of the over-desalination method of the present invention is significantly superior to that of the conventional over-desalination method. was confirmed, and can be said to be an extremely advantageous method in practice.

Example 2 Next, the crust separation effect when changing the water content of the anion exchange resin, which is another over-desalination method of the present invention, is compared with the conventional over-desalination operation using a single-bed mini column test. .

Test Conditions The test was conducted using the test apparatus shown in Figure 4 under the following test conditions.

Γ resin specifications: Strongly basic gel type anion exchange resin (OH type) with water content of 46, 50, 56, 71% Γ resin amount: 15 ml Γ Linear water flow velocity: LV = 108 m/h Γ through Water period: Approximately 2 weeks Test results The results of the single-bed mini-column test using only anion exchange resin are shown in Figure 8, which shows that increasing the water content improves the crud separation effect. It could be confirmed.

Incidentally, FIG. 8 is a graph showing the relationship between the water content of a strongly basic gel type anion exchange resin and the cladding capture ratio when a product with a water content of 55% is taken as 1.

The above test results were obtained by changing the water content of the anion exchange resin, and in general, the effect of anion exchange resin on the cladding separation effect during over-desalination operation is different from that of cation exchange resin due to its nature. Although small, it has been confirmed that the crud separation effect of the over-desalination method of the present invention is significantly superior to that of conventional methods, particularly due to the synergistic effect of the mixed bed with the cation exchange resin, and is extremely advantageous in practice. This can be said to be a great method.

Furthermore, the over-desalination method of the present invention is an over-desalination method using a mixed bed of resins in which the water content of the cation exchange resin and anion exchange resin is increased compared to the conventional product. Over-desalination method using a mixed bed of a resin with a higher water content than the conventional ion exchange resin and a conventional cation exchange resin.In the upper layer of the mixed bed of the conventional ion exchange resin, a cation exchange resin with a higher water content than the conventional product is used. It is assumed that the excessive demineralization method using a resin bed laminated with a resin bed has a crud separation effect superior to the above-mentioned effect, but a recent test has confirmed an excellent crud separation effect, and both are extremely effective in practical use. This can be said to be an advantageous method.

〔Effect of the invention〕

In the present invention, compared to the conventional mixed bed over-desalination method, the anion/cation exchange resin has a high water content, so it has a high affinity with the highly hydrophilic cladding.
Since the crud separation effect is large, high purity water with a lower crud concentration can be obtained during excessive desalination.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between water content and crushing strength of a strongly acidic gel type cation exchange resin, Figure 2 is a graph showing the relationship between water content and total exchange capacity of a cation exchange resin, and Figure 2 is a graph showing the relationship between water content and total exchange capacity of a cation exchange resin. Figure 3 is a graph showing the relationship between water content and total exchange capacity of a strongly basic gel-type anion exchange resin, Figure 4 is a schematic diagram of a water-flowing mini-column test device, and Figure 5 is a graph showing the relationship between water content and total exchange capacity of a strongly basic gel-type anion exchange resin. This is a graph showing the relationship between the moisture content of the resin and the crud separation ability, Figure 6 is a schematic diagram of the mixed bed actual length column test device, and Figure 7 is the relationship between the moisture content of the cation exchange resin and the DF value. This is a graph representing the eighth
The figure is a graph showing the relationship between the water content of the anion exchange resin and the trapping ability of the cladding. 1... Raw water inlet, 2... Pure water inlet for cleaning, 3...
... Resin-filled column, 4 ... Main flow meter, 5 ... Filter, 6 ... Flow meter, 7 ... Integrating flow meter, 8 ...
Conductivity meter, 9...Drain line.

Claims (1)

[Claims] 1. A method for excessive desalination using a mixed bed consisting of a granular or powdered cation exchange resin and an anion exchange resin when treating secondary system water of a PWR nuclear power plant, A mixed bed is formed using a cation exchange resin and/or anion exchange resin whose water content is increased (55 to 75%) from the standard value (45 to 55%) of conventional gel-type resins. , a mixed-bed over-desalination method characterized by enhanced ability to remove suspended impurities during secondary system water treatment of PWR nuclear power plants. 2. In the process of excessive desalination using a mixed bed consisting of granular or powdered cation exchange resin and anion exchange resin when treating secondary system water of a PWR type nuclear power plant, conventional ion exchange resin The standard value of conventional gel type resin (45
~55%) with increased moisture content (55~75
%) of cation-exchange resin layered to form a resin bed, which enhances the ability to remove suspended impurities during secondary system water treatment in PWR nuclear power plants. Salt method.