JP3960930B2 - Ion exchange resin filling method for condensate demineralizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of filling an ion exchange resin into a condensate demineralizer provided in a condensate piping system of a nuclear or thermal power plant.
[0002]
[Prior art]
It is known that the treated water of the condensate demineralizer contains several kinds of organic impurities. These are impurities mainly eluted from the ion exchange resin packed in the desalting tower, and are generated when the ion exchange resin is subjected to oxidative decomposition by dissolved oxygen or an oxidizing agent. Among them, the organic impurities eluted from the cation exchange resin are mainly polystyrene sulfonic acid (hereinafter sometimes abbreviated as PSS), which has recently been a problem because it is decomposed in a nuclear reactor or a steam generator to generate sulfate ions. It has become. That is, since sulfuric acid causes corrosion of the structural material and scale generation, it is desirable to reduce it as much as possible, and several methods for reducing the generation of sulfate ions have been proposed.
[0003]
As one of the reduction methods, the ion exchange resin layer formed in the desalting tower is divided into upper and lower, and the upper layer is a mixed ion exchange resin in which a cation exchange resin and an anion exchange resin are mixed, or a layer of a cation exchange resin alone, A method has been proposed in which the lower layer is made of an anion exchange resin alone (Patent Document 1). In this method, since the anion exchange resin in the lower part of the desalting tower adsorbs PSS eluted from the upper layer, the PSS concentration in the treated water can be reduced.
[0004]
However, when a desired upper and lower two-layer ion exchange resin layer is formed in the desalting tower as described above, there are the following problems. That is, since the specific gravity of anion exchange resin is generally smaller than that of cation exchange resin, when the ion exchange resin is filled into the demineralization tower, the anion exchange resin is first received and an anion exchange resin layer is formed in the lower part of the demineralization tower. However, when receiving the mixed ion exchange resin thereon, the resin layer in the desalting tower becomes a fluid state, the anion exchange resin rises and moves to the upper part of the mixed ion exchange resin layer. There arises a problem that the amount of anion exchange resin in the lower part of the column is reduced. When the amount of the anion exchange resin in the lower part of the desalting tower decreases, it becomes difficult to capture PSS, the PSS concentration in the treated water increases, and the target effect of reducing the PSS concentration in the treated water by dividing into two layers is obtained. Absent. In addition, when filling the slurry of the mixed ion exchange resin, the upper surface of the anion exchange resin layer formed in the lower part of the desalting tower is disturbed, the thickness of the anion exchange resin layer becomes uneven, and the thickness is thin. There is also a possibility that the PSS removability is deteriorated in a part.
[0005]
For such a problem, the present applicant has previously proposed a structure in which a drooping wall is provided in the lower part of the desalting tower to suppress the flow of the anion exchange resin layer (Patent Document 2).
[0006]
In addition, although not in the case of forming an upper and lower two-layer ion exchange resin layer, as a method of filling the desalting tower while suppressing the separation of the mixed resin to be charged into a cation exchange resin and an anion exchange resin, A method of filling a mixed resin while making a downward flow of water in the desalting tower has also been proposed (Patent Document 3).
[0007]
[Patent Document 1]
JP-A-9-276862 (Claims)
[Patent Document 2]
JP 2000-167551 A (Claims)
[Patent Document 3]
JP 2002-1328 A (Claims)
[0008]
[Problems to be solved by the invention]
However, the method of providing the hanging wall described in Patent Document 2 can be implemented without any problem if it is a newly installed plant. However, it is possible to modify radiation of a BWR plant (boiling water nuclear power plant) by modifying an existing plant. In remodeling involving welding work and lining repairs in the controlled area, it becomes considerably difficult to actually carry out.
[0009]
Further, since Patent Document 3 describes a case where only one kind of mixed resin layer is formed in the desalting tower, when it is assumed that two different upper and lower ion exchange resin layers are formed. Cannot be applied as is.
[0010]
The object of the present invention is to form the upper ion exchange resin while forming the lower ion exchange resin layer in a desired form, particularly when forming two different upper and lower ion exchange resin layers in the desalting tower. To the demineralization tower of the condensate demineralization apparatus capable of reliably forming the target two-layer ion exchange resin layer in the tower and obtaining the desired effect of reducing the PSS concentration in the treated water An ion exchange resin filling method is provided.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, an ion exchange resin filling method for a condensate demineralizer according to the present invention comprises an upper ion exchange resin layer comprising a mixed resin A of a cation exchange resin and an anion exchange resin in a demineralization tower. When forming two different upper and lower ion exchange resin layers of the anion exchange resin alone or the lower ion exchange resin layer made of the mixed resin B having a higher ratio of the anion exchange resin than the mixed resin A, After filling the salt tower with the anion exchange resin or mixed resin B together with the transfer water to form the lower ion exchange resin layer, the demineralizer is replenished with water to raise the water level in the demineralizer. After giving the water depth to the upper surface of the lower ion exchange resin layer, the mixed resin A is filled together with the transfer water while forming a downward flow in the desalting tower by draining water from the desalting tower, The lower ion exchange tree Consists method characterized by forming the upper ion-exchange resin layer on the layer. The water depth is preferably at least 200 mm, preferably 300 mm or more from the upper surface of the lower ion exchange resin layer. Further, in the method according to the present invention, as a result of providing the water depth to the upper surface of the lower ion exchange resin layer as described above, even if the inside of the desalting tower becomes full, there is no problem. Such an embodiment is also included in the scope of the present invention.
[0012]
In the method according to the present invention, the replenishment of water can be performed from the lower side of the demineralization tower or from the upper side of the demineralization tower. When water is replenished from the lower side, it can be expected that the lower ion exchange resin layer that has already been formed is in a slightly fluidized state and the upper surface (grain surface) is smoothed. This replenishment mode is particularly suitable when the lower ion exchange resin layer is formed of the anion exchange resin alone. In this case, the separation within the layer is performed even if the lower ion exchange resin layer is somewhat fluidized. Does not occur. On the other hand, the replenishment of water from the upper side is particularly suitable when the lower ion exchange resin layer is formed from the mixed resin B rich in anion exchange resin. In this case, the replenishment is performed from the upper side. The side ion exchange resin layer is basically not in a fluid state, and separation of the cation and anion exchange resin inside is suppressed. However, in this case, it is preferable to supply water so as not to greatly disturb the upper surface of the lower ion exchange resin layer that has already been formed.
[0013]
In addition, after the replenishment of water, a short time of water replenishment (instantaneous from the lower side of the desalting tower is performed in order to give an instantaneous flow to the lower ion exchange resin layer and level the upper surface of the lower ion exchange resin layer. Water replenishment). This makes it possible to align the upper surface of the lower ion exchange resin layer as flat as possible before receiving the mixed resin A.
[0014]
Furthermore, even after filling with the mixed resin A, water is replenished for a short time from the lower side of the desalting tower in order to give an instantaneous flow to the upper ion exchange resin layer and level the upper surface of the upper ion exchange resin layer. be able to. This makes it possible to align the top surface of the entire ion exchange resin layer finally filled in the desalting tower as flat as possible.
[0015]
In the ion exchange resin filling method to the condensate demineralization apparatus according to the present invention as described above, after the anion exchange resin or the mixed resin B is filled with the transfer water to form the lower ion exchange resin layer, the deionization resin is removed. Water is replenished in the salt tower, the water level in the desalting tower is raised, and a water depth of a predetermined depth or more is given to the upper surface of the lower ion exchange resin layer. That is, a sufficient amount of water is secured to drain water into the desalting tower. From this state, when the water is extracted from the desalting tower, a downward flow is formed in the desalting tower, and while the downward flow is formed, that is, in the state where the downward flow is formed, the mixed resin A Are filled together with the transfer water, and an upper ion exchange resin layer is formed on the lower ion exchange resin layer. When the downward flow is formed and the state is continued, the force that presses the resin layer downward continues to act on the lower ion exchange resin layer that has already been formed. Even during filling, the lower ion exchange resin layer continues to be maintained in a predetermined form. As a result, the target ion exchange resin layer in the upper and lower two-layer form is formed in the desalting tower without particularly disturbing the upper surface of the lower ion exchange resin layer.
[0016]
Further, when the mixed resin A is filled together with the transfer water by providing a water depth of a predetermined depth or more on the upper surface of the lower ion exchange resin layer, it exists on the upper surface of the lower ion exchange resin layer. The water layer that functions as a buffer layer suppresses the occurrence of turbulence of the upper surface of the lower ion exchange resin layer due to the mixed resin A or its transferred water flowing in. Thereby, the target ion-exchange resin layer of the upper and lower two-layer form is more reliably formed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a method according to the present invention will be described with reference to the drawings.
FIGS. 1 to 5 show the case where the ion exchange resin filling method in the demineralization tower in the condensate demineralization apparatus according to one embodiment of the present invention is applied to the vertical cylindrical demineralization tower in the BWR plant. The method is shown in the order of steps. FIG. 1 shows that an anion exchange resin or a mixed resin B (a mixed resin having a higher ratio of anion exchange resin than the mixed resin A forming the upper ion exchange resin layer) is sent from a regeneration tower or the like together with transfer water into the desalting tower. It shows how the lower ion exchange resin layer is formed by filling the desalting tower. A resin transfer pipe 3 for introducing a lower ion exchange resin slurry 2 (mixed form of lower ion exchange resin and transfer water) into the desalting tower 1 and a vent pipe 4 are provided at the upper part of the desalting tower 1. It has been. The lower ion exchange resin 5 transferred through the resin transfer pipe 3 is filled in the desalting tower 1 and is provided in the lower part of the desalting tower 1, in the illustrated example, in the lower part of the desalting tower 1. 6, the lower ion exchange resin layer 7 is formed. At this time, excess transfer water may be extracted (drained) through a drain pipe 8 provided in the lower part of the desalting tower 1 as necessary. When the transfer of the lower ion exchange resin slurry 2 is completed, the upper surface of the lower ion exchange resin layer 7 is usually not flat and often irregularly disturbed, as shown in FIG.
[0018]
Next, as shown in FIG. 2, makeup water 9 is supplied into the desalting tower 1 from the lower part of the desalting tower 1 using, for example, a drain pipe 8 to raise the water level in the desalting tower 1. A predetermined water depth H is given to the upper surface of the lower ion exchange resin layer 7. The water depth H should be at least 200 mm, preferably 300 mm or more. In addition, since the lower ion exchange resin layer 7 is brought into a slightly flowable state by replenishing water from the lower part of the demineralization tower 1, there is an effect that the upper surface of the lower ion exchange resin layer 7 is flattened. . In order to further flatten the upper surface, for example, after replenishing water so that the predetermined water depth H is obtained, water is instantaneously supplied at a higher flow rate (short-time water replenishment), and lower ions are supplied. The exchange resin layer 7 may be instantaneously flowed to adjust the upper surface (grain surface).
[0019]
Although not shown, makeup water for providing the water depth H can be supplied from the upper part of the demineralization tower 1. The supply from the lower part of the desalting tower 1 has the effect of making the lower ion exchange resin layer 7 slightly flowable and flattening its upper surface, but at this time, the lower ion exchange resin layer 7 is formed. When the lower ion exchange resin 5 is the mixed resin B, the cation exchange resin and the anion exchange resin may be separated and classified due to the difference in specific gravity. This is particularly effective when the lower ion exchange resin layer 7 has an anion exchange resin alone. On the other hand, in the supply from the upper part of the desalting tower 1, separation in the lower ion exchange resin layer 7 as in the case of the supply from the lower part does not substantially occur. This is effective when the side ion exchange resin layer 7 is formed of the mixed resin B.
[0020]
After the lower ion exchange resin layer 7 is formed as described above and given a predetermined water depth H, the water in the desalting tower 1 is drained through the drain pipe 8 at the lower part of the desalting tower 1 as shown in FIG. By pulling out, while forming a downward flow R in the water present in the desalting tower 1, the upper ion exchange resin slurry 10 (upper ion exchange resin [mixed resin A ] And mixed water) are fed into the desalting tower 1. The upper ion exchange resin 11 (mixed resin A) transferred into the desalting tower 1 is filled on the lower ion exchange resin layer 7 in the desalting tower 1 to form an upper ion exchange resin layer 12. Go. At this time, since the state where the downward flow R is formed is maintained, the force that presses the resin layer 7 downward continues to act on the already formed lower ion exchange resin layer 7, The lower ion exchange resin layer 7 is kept in a predetermined desired form even while the upper ion exchange resin 11 is being filled in. In addition, since there is a water layer having a depth above the lower ion exchange resin layer 7, even if the upper ion exchange resin 11 or its transfer water is dropped into the tower vigorously, Serves as a buffer. Therefore, also from this surface, the disturbance of the upper surface of the lower ion exchange resin layer 7 is suppressed, and the lower ion exchange resin layer 7 is kept in a predetermined desirable form.
[0021]
Further, in the process of forming the upper ion exchange resin layer 12 while forming the downward flow R, the make-up water 13 may be supplied from the upper side of the desalting tower 1 through the vent pipe 4 at the same time. Good. By replenishing the makeup water 13, a sufficient amount of water in the desalting tower 1 having the water depth H is secured, and even if the flow rate of the descending flow R is increased, the water depth is prevented from excessively decreasing. Therefore, the function of holding the lower ion exchange resin layer 7 in a predetermined desired form is maintained. It is also possible to supply pressurized air instead of or together with the makeup water 13. By supplying the pressurized air, the action of pressing the lower ion exchange resin layer 7 downward and maintaining its form is reinforced.
[0022]
Further, since the process of forming the upper ion exchange resin layer 12 is performed in a state where the downward flow R is formed, the separation of the upper ion exchange resin 11 being filled, that is, the mixed resin A (cation exchange). The separation of the resin and the anion exchange resin) is also suppressed, and the upper ion exchange resin layer 12 is formed in a desirable mixed state.
[0023]
After the upper ion exchange resin layer 12 is formed in this way, it may be assumed that some disturbance remains on the upper surface. In this case, for example, as shown in FIG. 4, make-up water 14 is instantaneously supplied from the lower part of the desalting tower 1 (short-time water supply is performed), and the upper ion-exchange resin layer 12 flows instantaneously. Thus, the upper surface (grain surface) can be made flat. However, if this operation is unnecessary, it can be omitted.
[0024]
After forming the lower ion exchange resin layer 7 and the upper ion exchange resin layer 12 in a desired desirable form in the demineralization tower 1 as described above in two upper and lower layers, as shown in FIG. The makeup water 15 is supplied from the upper side, and excess water is drained from the vent pipe 4 so that the inside of the desalting tower 1 is filled with water.
[0025]
In the above embodiment, the case where the present invention is applied to the vertical cylindrical demineralization tower in the BWR plant is shown. However, the present invention can be similarly applied to the spherical demineralization tower in the BWR plant, for example. Furthermore, the present invention can be similarly applied to a desalting tower having a resin inlet on a side surface. When the resin inlet is provided on the side surface of the desalting tower, the particle surface of the resin layer formed in the desalting tower tends to be higher in the portion near the resin inlet, By supplying the make-up water instantaneously, it is possible to level the grain surface appropriately.
[0026]
【The invention's effect】
As described above, according to the ion exchange resin filling method for the condensate demineralizer according to the present invention, the upper ion exchange resin layer is formed while maintaining the lower ion exchange resin layer in a desired form in the demineralization tower. Thus, both the upper and lower ion exchange resin layers can be formed in a desired desired form. The method according to the present invention can be easily carried out on an existing desalting tower without substantial modification of equipment. And the implementation of the method according to the present invention makes it possible to obtain a high PSS concentration reduction effect in the treated water.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a desalting tower showing one step in a method for filling an ion exchange resin into a condensate desalination apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of a desalting tower showing the next step of FIG.
FIG. 3 is a schematic longitudinal sectional view of a desalting tower showing the next step of FIG. 2;
4 is a schematic longitudinal sectional view of a demineralization tower showing the next step of FIG. 3. FIG.
FIG. 5 is a schematic longitudinal sectional view of a demineralization tower showing the next step of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Desalination tower 2 Lower ion exchange resin slurry 3 Resin transfer pipe 4 Vent pipe 5 Lower ion exchange resin 6 Eyeplate 7 Lower ion exchange resin layer 8 Drain pipe 9 Make-up water 10 Upper ion exchange resin slurry 11 Upper ion exchange Resin 12 Upper ion exchange resin layer 13 Makeup water 14 Makeup water 15 Makeup water H Water depth R Downflow

Claims (5)

In the desalting tower, an upper ion exchange resin layer made of a mixed resin A of a cation exchange resin and an anion exchange resin, and a lower resin made of an anion exchange resin alone or a mixed resin B having a higher ratio of the anion exchange resin than the mixed resin A When forming two different upper and lower ion exchange resin layers with the side ion exchange resin layer, the anion exchange resin or mixed resin B is filled together with transport water in the desalting tower to form the lower ion exchange resin layer. After the formation, water is replenished in the desalting tower to raise the water level in the desalting tower so that the upper surface of the lower ion exchange resin layer has a water depth, and then the water is drained from the desalting tower. Thus, the mixed resin A is filled with the transfer water while forming a downward flow in the demineralization tower, and an upper ion exchange resin layer is formed on the lower ion exchange resin layer. Ion exchange with salt equipment Resin filling method. The method for filling an ion exchange resin into a condensate demineralizer according to claim 1, wherein the water is replenished from the lower side of the demineralization tower. The method for filling ion-exchange resin into a condensate demineralizer according to claim 1, wherein the water is replenished from the upper side of the demineralization tower. After the replenishment of water, in order to give an instantaneous flow to the lower ion exchange resin layer and level the upper surface of the lower ion exchange resin layer, water is replenished for a short time from the lower side of the demineralization tower. Item 4. A method for filling an ion exchange resin into a condensate demineralizer according to any one of Items 1 to 3. After the filling of the mixed resin A, short-time water replenishment is performed from the lower side of the demineralization tower in order to give an instantaneous flow to the upper ion exchange resin layer to level the upper surface of the upper ion exchange resin layer. Item 5. A method for filling an ion exchange resin into a condensate demineralizer according to any one of Items 1 to 4.

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