JP3947818B2 - Cation exchange resin regeneration tower - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cation exchange resin regeneration tower (hereinafter simply referred to as “cation regeneration tower”) used when regenerating a mixed ion exchange resin comprising a cation exchange resin and an anion exchange resin.
[0002]
[Prior art]
Conventionally, as an apparatus for treating the condensate of a thermal power plant or a nuclear power plant, for example, an ion exchange device including a plurality of mixed bed ion exchange towers has been used. The mixed bed ion exchange tower is filled with a mixed ion exchange resin in which a cation exchange resin and an anion exchange resin are mixed at a predetermined ratio. If the ion exchange capacity of the mixed ion exchange resin is reduced by using a mixed bed type ion exchange tower, or if a constant yield is reached, it is necessary to regenerate the mixed ion exchange resin using a regeneration facility attached to the ion exchange device. There is. When the mixed ion exchange resin is regenerated, the mixed bed ion exchange column to be regenerated is usually switched to a preparatory column filled with the regenerated mixed ion exchange resin.
[0003]
For example, as conceptually shown in FIG. 3, the regeneration facility includes a cation regeneration tower 1 that regenerates the cation exchange resin K of the used mixed ion exchange resin, and an anion exchange resin A of the mixed ion exchange resin. An anion exchange resin regeneration tower (hereinafter simply referred to as “anion regeneration tower”) 2 to be regenerated, and a resin storage tank 3 for storing each ion exchange resin regenerated in these regeneration towers 1 and 2 for the next use It has. The mixed bed type ion exchange tower (not shown) and the cation regeneration tower 1 are connected via the first transfer line 4 and used from the mixed bed type ion exchange tower to the cation regeneration tower 1 via the first transfer line 4. After receiving the mixed ion exchange resin already used and backwashing and separating the mixed ion exchange resin as a cation exchange resin and an anion exchange resin in the cation regeneration tower 1, the anion exchange resin is transferred to the anion regeneration tower 2 as described later. Only the cation exchange resin is left in the cation regeneration tower 1, and an acid regenerant is poured into the cation regeneration tower 1 to regenerate the cation exchange resin. The cation regeneration tower 1 and the anion regeneration tower 2 are connected via a second transfer line 5, and after receiving an anion exchange resin from the cation regeneration tower 1 into the anion regeneration tower 2 via the second transfer line 5, anion regeneration is performed. An alkali regenerant is passed through the tower 2 to regenerate the anion exchange resin. The cation regeneration tower 1 and the anion regeneration tower 2 are connected to the resin storage tank 3 via the third transfer line 6, respectively, and the regenerated cation exchange resin from the regeneration towers 1 and 2 via the third transfer line 6. The anion exchange resin is transferred to the resin storage tank 3, and the regenerated ion exchange resin is stored in the resin storage tank 3 for the next use.
[0004]
Thus, when the mixed ion exchange resin is backwashed and separated and settled in the cation regeneration tower 1, the cation exchange resin K becomes the lower layer and the anion exchange resin A becomes the upper layer due to the difference in specific gravity, and at the boundary between the two ion exchange resins. A separation boundary surface S is formed. However, it is difficult to completely separate the cation exchange resin and the anion exchange resin, and in the vicinity of the separation boundary surface S, there is a mixed layer in which both ion exchange resins are mixed. Even if the mixed ion exchange resin M in this mixed layer is transferred to any of the regeneration towers 1 and 2, the ion exchange resin is reversely regenerated (the cation exchange resin is in contact with the alkali regenerant and the anion exchange resin is in contact with the acid regenerant). In order to receive this phenomenon, an amount suitable for the mixed ion exchange resin is prepared in advance and replenished into the cation regeneration tower 1 before the backwash separation, and the mixed ion exchange resin in the mixed layer is subjected to cation regeneration after the backwash separation. It removes from the tower 1 and regenerates in each of the regeneration towers 1 and 2. In this case, even if the mixed ion exchange resin is removed, the ion exchange resin to be returned to the mixed bed type ion exchange tower remains in each regeneration tower 1 and 2, and the reverse regeneration in each regeneration tower 1 and 2 is prevented. it can. That is, a mixed ion exchange resin storage tank (hereinafter simply referred to as “circulation resin storage tank”) 7 for circulation is connected to the cation regeneration tower 1 via the fourth and fifth transfer lines 8 and 9. The mixed ion exchange resin M stored in 7 is circulated and used during regeneration.
[0005]
Hereinafter, a conventional reproducing method will be described with reference to FIG. When the mixed ion exchange resin in the mixed bed type ion exchange tower reaches the through-flow point and the ion exchange capacity is lost or a constant yield is reached, first, the mixed ion exchange resin after use is transferred to the first transfer line 4. Then, the circulating mixed ion exchange resin M is transferred from the circulation resin storage tank 7 into the cation regeneration tower 1 through the fourth transfer line 8 and the first transfer line 4. Next, as shown in FIG. 3, when the backwash water 50 is supplied in an upward flow from the bottom of the cation regeneration tower 1, the mixed ion exchange resin is fluidized and the capacity of the ion exchange resin expands to about twice and the mixed ion exchange resin. Are separated by specific gravity difference. Next, when the backwash water is stopped from flowing, the ion exchange resin settles, so that the upper layer is formed of the anion exchange resin A and the lower layer is formed of the cation exchange resin K as shown in FIG.
[0006]
Next, after a small amount of anion exchange resin remains above the separation boundary surface S and most of the other anion exchange resin A is transferred from the cation regeneration tower 1 to the anion regeneration tower 2 via the second transfer line 5. Furthermore, a small amount of the remaining anion exchange resin and a small amount of the cation exchange resin below the separation boundary surface S are circulated from the cation regeneration tower 1 through the fifth transfer line 9 as a mixed ion exchange resin M for circulation. It is returned to the resin storage tank 7 and stored as a mixed ion exchange resin for circulation to be replenished at the next regeneration. Thereafter, according to a conventional method, in the cation regeneration tower 1, the cation exchange resin K remaining in the tower is regenerated with an acid regeneration agent, and in the anion regeneration tower 2, the anion exchange resin is regenerated with an alkali regeneration agent. Is transferred to the resin storage tank 3 through the third transfer line 6 to prepare for the next use. Thus, by using the mixed ion exchange resin M for circulation, reverse regeneration of the ion exchange resin in each of the regeneration towers 1 and 2 can be prevented, and it can be regenerated as a mixed ion exchange resin to obtain high-purity treated water. .
[0007]
By the way, in the cation regeneration tower 1, as shown in FIG. 4, a high-order nozzle 1A and a low-order nozzle 1B used when taking out most of the anion exchange resin A after the backwash separation and the mixed ion exchange resin M for circulation separately. Is attached. The upper nozzle 1A is attached to a position where only the anion exchange resin almost not mixed with the cation exchange resin is taken out above the separation boundary surface S after the backwash separation, and the lower nozzle 1B is separated from a small amount of the remaining anion exchange resin. A small amount of cation exchange resin below the boundary surface S is attached to a position where it is taken out as a mixed ion exchange resin M for circulation.
[0008]
[Problems to be solved by the invention]
However, in the case of the conventional cation regeneration tower 1, when the mixed ion exchange resin after use is regenerated as described above, the mixed ion exchange resin M for circulation is added to the mixed ion exchange resin and the cation regeneration tower 1 is recovered. However, since the amount of resin in the cation regeneration tower 1 is large, when the backwash separation is performed, the backwash separation operation is reversed at the corner portion between the support bed of the cation exchange resin K and the tower body. The flow rate of the washing water is not sufficient, and the mixed ion exchange resin in this portion is difficult to fluidize, and as shown in FIG. 4, a small amount of anion exchange resin A ′ remains in the corner portion and the like after backwash separation, and the cation regeneration tower 1 When the cation exchange resin K is regenerated, the residual anion exchange resin A ′ is reversely regenerated by the acid regenerant.
[0009]
The present invention has been made to solve the above problems, and the ion exchange resin is sufficiently fluidized even in a corner portion between the support bed of the cation exchange resin and the tower body, and after backwash separation, the ion exchange resin is contained in the cation exchange resin. An object of the present invention is to provide a cation regeneration tower in which anion exchange resin does not remain, and reverse regeneration of the anion exchange resin can be almost eliminated during the regeneration.
[0010]
[Means for Solving the Problems]
The cation regeneration tower according to claim 1 of the present invention accepts a mixed ion exchange resin comprising a used cation exchange resin and an anion exchange resin and a mixed ion exchange resin for circulation, and converts these mixed ion exchange resins into anions. Separating the exchange resin into the upper layer and the cation exchange resin into the lower layer, the majority of the anion exchange resin above the separation interface of both ion exchange resins, and a small amount of cation exchange below the remainder of the anion exchange resin and the separation interface In the cation exchange resin regeneration tower for regenerating the remaining cation exchange resin by taking out the resin from the outside of the tower, an upper outlet for taking out most of the anion exchange resin, and a lower outlet for the upper outlet, Between these two outlets between the remaining anion exchange resin and the lower outlet from which a small amount of cation exchange resin below the separation interface is taken out. In which characterized in that a middle outlet for taking out a part of the ion exchange resin located.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the following, the present invention will be described based on the embodiment shown in FIG. 1 and FIG. In each figure, FIG. 1 shows the state of the main part of the regeneration facility in the step of backwashing and separating the mixed ion exchange resin after use using the regeneration facility to which the cation regeneration tower of one embodiment of the present invention is applied. FIG. 2 is a conceptual diagram showing, and FIG. 2 is a view corresponding to FIG. 1 showing a state in which a part of the mixed ion exchange resin for circulation is taken out from the cation regeneration tower shown in FIG.
[0012]
The regeneration facility to which the cation regeneration tower of this embodiment is applied includes a cation regeneration tower 1, an anion regeneration tower 2, and a circulating resin storage tank 7, for example, as shown in FIGS. Except for the conventional configuration. In the cation regeneration tower 1 of this embodiment, the backwash separation operation is performed twice, and the mixed ion exchange resin M for circulation in the cation regeneration tower 1 is extracted in two portions.
[0013]
Thus, as shown in FIG. 1 and FIG. 2, the cation regeneration tower 1 includes an anion exchange resin A after adding a circulating mixed ion exchange resin M to the used mixed ion exchange resin and backwashing and separating it. The upper nozzle 1A, which is the upper outlet for taking out most of the gas, and the recirculation mixing of the remaining portion of the anion exchange resin A and a small amount of the cation exchange resin K below the separation boundary surface S disposed below the upper nozzle 1A A lower nozzle 1B that is a lower outlet to be taken out as the ion exchange resin M, and a middle outlet that is arranged between the two nozzles 1A and 1B and takes out a part of the mixed ion exchange resin M after the backwash separation operation. A middle nozzle 1C. Therefore, the present embodiment is characterized in that the middle nozzle 1C is provided between the upper and lower nozzles 1A and 1B. The middle nozzle 1C is connected to the fifth transfer line 9 via the sixth transfer line 10, and a part of the mixed ion exchange resin M is taken out from the middle nozzle 1C, and the sixth transfer line 10 and the fifth transfer line. It is made to transfer to the circulation resin storage tank 7 through 9.
[0014]
The upper nozzle 1A is arranged above the separation boundary surface S separated by the first backwash separation operation (for example, 250 mm above the separation boundary surface S) at a position to take out the anion exchange resin A almost not mixed with the cation exchange resin. The lower nozzle 1B is disposed at a position where a small amount of remaining anion exchange resin and a small amount of cation exchange resin below the separation boundary surface S are taken out as a mixed ion exchange resin M for circulation. Arranged in the cation regeneration tower 1. Further, as described above, the middle nozzle 1C is a position where a part of the mixed ion exchange resin after taking out the anion exchange resin A from the upper nozzle 1A above the separation boundary surface S can be extracted as the mixed ion exchange resin M for circulation. Arranged in the cation regeneration tower 1.
[0015]
Next, a backwash separation method using the cation regeneration tower 1 will be described with reference to FIGS. First, the mixed ion exchange resin after use is transferred from the mixed bed type ion exchange tower (not shown) into the cation regeneration tower 1 through the first transfer line 4 (see FIG. 3), and then the circulating resin storage tank 7 is used. After the mixed ion exchange resin M for circulation is transferred into the cation regeneration tower 1 through the fourth transfer line 8, the mixed ion exchange resin is fed into the cation regeneration tower 1 while supplying backwash water from the bottom thereof. 1, the capacity expands to about twice, and the mixed ion exchange resin separates due to the difference in specific gravity. As shown in FIG. 1, the anion exchange resin gathers in the upper layer and the cation exchange resin gathers in the lower layer. Thereafter, when the backwash water flow is stopped, the upper layer becomes anion exchange resin A and the lower layer becomes cation exchange resin K as shown in FIG. 1, and the separation boundary surface S is formed at the boundary between both ion exchange resins. Is done. When most of the anion exchange resin A in the cation regeneration tower 1 separated by the first backwash separation operation is taken out from the upper nozzle 1A and transferred to the anion regeneration tower 2 via the second transfer line 5, a separation boundary surface is obtained. As shown in FIG. 1, only a substantially pure anion exchange resin A in which the cation exchange resin K mixed in the anion exchange resin in the vicinity of the upper part of S is almost not mixed in the anion regeneration tower 2 without being taken out. Filled.
[0016]
Next, a part of the mixed ion exchange resin M in the cation regeneration tower 1 is taken out from the middle nozzle 1C disposed in the vicinity of the separation boundary surface S and transferred into the circulating resin storage tank 7 through the sixth transfer line 10. The capacity of the mixed ion exchange resin M in the cation regeneration tower 1 is reduced from the state shown by the one-dot chain line in FIG. 2 to the state shown by the solid line. Next, a second backwash separation operation is performed in this state. That is, when the backwashing water 50 is supplied from the bottom of the cation regeneration tower 11 and a gas 60 such as compressed air is supplied to bubble the ion exchange resin in the tower in the backwashing water, the anion at the corner in the tower The exchange resin is fluidized evenly. Thereafter, the supply of the gas 60 is stopped, the backwashing water 50 alone is supplied for backwashing separation, and then the backwashing water 50 is stopped, the mixed ion exchange resin is calmed and separated again. The anion exchange resin slightly remaining in the corner portion between the support floor and the tower body gathers in the upper layer and comes to be positioned above the lower nozzle 1B. In the case of this second backwash separation operation, the amount of resin is markedly reduced compared to the case of the first backwash separation operation. The flow is promoted, the anion exchange resin in the corner portion is also fluidized reliably, and the residual amount of the anion exchange resin in the lower cation exchange resin K can be remarkably suppressed. Subsequently, the remaining part of the mixed ion exchange resin M in the cation regeneration tower 1 is taken out from the lower nozzle 1B as a mixed ion exchange resin for circulation, and is transferred to the circulation resin storage tank 7 through the fifth transfer line 9. Only a substantially pure cation exchange resin K is left.
[0017]
Thereafter, the cation exchange resin K is regenerated with an acid regenerant such as hydrochloric acid or sulfuric acid in the cation regeneration tower 1 and the anion exchange resin A is regenerated with an alkali regenerant such as sodium hydroxide in a conventional manner. Since the cation regeneration tower 1 contains almost no anion exchange resin, and the anion regeneration tower 2 contains almost no cation exchange resin, a reverse regeneration phenomenon may occur in each of the regeneration towers 1 and 2. Absent. Therefore, if the regenerated cation exchange resin K and the anion exchange resin A are mixed in a resin storage tank (see FIG. 3) and then used in a mixed bed ion exchange tower, high-purity treated water can be obtained.
[0018]
As described above, according to this embodiment, since the middle nozzle 1C for taking out a part of the mixed ion exchange resin M for circulation is provided between the upper nozzle 1A and the lower nozzle 1B, the mixing is performed up to the height of the middle nozzle 1C. The amount of resin in the anion regeneration tower 1 can be reduced by taking out the ion exchange resin, the fluidization of the ion exchange resin in the tower can be promoted, and the residual amount of the anion exchange resin in the corner portion in the tower can be suppressed. As a result, reverse regeneration of the anion exchange resin in the cation regeneration tower 1 can be significantly suppressed, and the quality of the treated water can be improved.
[0019]
The present invention is not limited to the above-described embodiment, and in short, a cation regeneration in which a middle nozzle for taking out a part of the mixed ion exchange resin after the backwash separation operation is attached between the upper nozzle and the lower nozzle. Any tower is included in the present invention.
[0020]
【The invention's effect】
According to the present invention, the ion exchange resin is sufficiently fluidized even in the corner portion between the support bed of the cation exchange resin and the tower body, and the anion exchange resin does not remain in the cation exchange resin after the backwash separation, and the regeneration thereof. It is possible to provide a cation regeneration tower that sometimes eliminates the reverse regeneration of the anion exchange resin.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a state of a main part of a regeneration facility in a step of backwashing and separating a mixed ion exchange resin after use using a regeneration facility to which a cation regeneration tower according to an embodiment of the present invention is applied. .
2 is a view corresponding to FIG. 1 showing a state in which a part of the mixed ion exchange resin for circulation is taken out from the cation regeneration tower shown in FIG.
FIG. 3 is a conceptual diagram showing a main part of a conventional regeneration facility.
4 is a conceptual diagram showing a state of a cation regeneration tower showing a state where a mixed ion exchange resin for circulation is added to a mixed ion exchange resin after use using the regeneration facility shown in FIG. 3 and then backwashed and separated. .
[Explanation of symbols]
1 Cation regeneration tower 1A Upper nozzle 1B Lower nozzle 1C Middle nozzle 2 Anion regeneration tower 7 Circulating resin storage tank K Cation exchange resin A Anion exchange resin M Mixed ion exchange resin for circulation

Claims (1)

Accepts mixed ion exchange resin consisting of cation exchange resin and anion exchange resin after use and mixed ion exchange resin for circulation, and separates these mixed ion exchange resins into the upper layer and the cation exchange resin into the lower layer. The most part of the anion exchange resin above the separation boundary surface of both ion exchange resins and the remaining part of the anion exchange resin and a small amount of the cation exchange resin below the separation boundary surface are taken out of the column and left to remain. In the cation exchange resin regeneration tower for regenerating the resin, an upper outlet from which most of the anion exchange resin is taken out, and a small amount of the lower anion exchange resin and a small amount below the separation interface are arranged below the upper outlet. While taking out a part of the ion exchange resin located between these two outlets between the lower outlet from which the cation exchange resin is taken out Cation exchange resin regeneration column, characterized in that a outlet.

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