JP3947767B2 - Regeneration method of ion exchange resin - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for regenerating an ion exchange resin for 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 type 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. 5, the regeneration facility is a cation exchange resin regeneration tower (hereinafter simply referred to as “cation regeneration tower”) for regenerating the cation exchange resin K of the used mixed ion exchange resin. 1), an anion exchange resin regeneration tower (hereinafter simply referred to as "anion regeneration tower") 2 for regenerating the anion exchange resin A of the mixed ion exchange resin, and these regeneration towers 1, And a resin storage tank 3 for storing each ion exchange resin regenerated in 2 for the next use. The mixed bed type ion exchange tower (not shown) and the cation regeneration tower 1 are connected via a first transfer line 4, and the mixed bed type ion exchange tower and the cation regeneration tower 1 are connected via the first transfer line 4. and receiving the spent mixed ion exchange resin, after the backwash separated mixed ion exchange resin in the cation regeneration tower 1 into a cation exchange resin and an anion exchange resin, anion as described below anion exchange resin Transfer to the ion regeneration tower 2 to leave only the cation exchange resin in the cation regeneration tower 1, and regenerate the cation exchange resin by passing an acid regenerant into the cation regeneration tower 1. The cation regeneration tower 1 and the anion regeneration tower 2 are connected via a second transfer line 5, and an anion exchange resin is received from the cation regeneration tower 1 into the anion regeneration tower 2 via the second transport line 5. After that, an anion exchange resin is poured into the anion regeneration tower 2 to regenerate the anion exchange resin. The cation regeneration tower 1 and the anion regeneration tower 2 are respectively connected to the resin storage tank 3 through the third transfer line 6, and the regenerated cation from the regeneration towers 1 and 2 through the third transfer line 6. The ion exchange resin and the anion exchange resin are 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 becomes the lower layer and the anion exchange resin becomes the upper layer due to the difference in specific gravity, and 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 a mixed layer in which both ion exchange resins are mixed exists in the vicinity of the separation boundary surface S. The mixed ion exchange resin of this mixed layer is reversely regenerated regardless of whether it is transferred to any regeneration tower 1 or 2 (the cation exchange resin is in contact with the alkali regenerant and the anion exchange resin is in contact with the acid regenerant). Therefore, an amount suitable for the mixed ion exchange resin is prepared in advance and replenished in the cation regeneration tower 1 before the backwash separation, and after the backwash separation, the mixed ion exchange resin in the mixed layer is added. Removal from the cation regeneration tower 1 and regeneration in each regeneration tower 1 and 2 are performed. 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 the storage tank 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 mixed ion exchange resin M for circulation 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. 5, 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 is expanded to about twice and mixed ion exchange is performed. The resin is separated by the specific gravity difference. Next, when the inflow of backwashing water is stopped, the ion exchange resin is settled, 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. There is a mixed layer made of the mixed ion exchange resin M for circulation.
[0006]
Next, a small amount of the anion exchange resin is left 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. Then, 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 mixed via the fifth transfer line 9 as a mixed ion exchange resin M for circulation. It returns to the circulation resin storage tank 7 from the inside of the ion regeneration tower 1, and stores it as a mixed ion exchange resin for circulation to be replenished at the next regeneration. Thereafter, according to a conventional method, the cation regeneration tower 1 regenerates the cation exchange resin K remaining in the tower with an acid regeneration agent, and the anion regeneration tower 2 regenerates the anion exchange resin with an alkali regeneration agent. Each ion exchange resin is transferred to the resin storage tank 3 through the third transfer line 6 and is prepared 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]
[Problems to be solved by the invention]
However, in the case of the conventional ion exchange resin regeneration method, in addition to the mixed ion exchange resin to be regenerated, a mixed ion exchange resin for circulation M for preventing reverse regeneration is added to the cation regeneration tower 1 to mix ions. In order to backwash and separate the exchange resin, the volume of the ion exchange resin increases by the amount of the mixed ion exchange resin for circulation and the circulation mixed ion exchange resin M also expands during the backwash separation operation. it is inevitable to increase the tower height of the cation regeneration tower 1, it is inevitable to increase until the building for further equipment, construction costs of playback equipment is increased, moreover, the future, and space saving is promoted, There existed a subject that the reproduction | regeneration equipment became easy to receive restrictions, such as height restrictions. Incidentally, the layer height of the volume of the mixed ion exchange resin for circulation in the cation regeneration tower 1 is, for example, about 500 mm. If the expansion during backwashing is included in this, the height of the cation regeneration tower 1 The increase reaches about 1000 mm.
[0008]
The present invention has been made to solve the above-mentioned problems, and can lower the height of the cation regeneration tower to reduce the construction cost of the regeneration facility, and at the same time, greatly suppress the reverse regeneration of the mixed ion exchange resin. Another object of the present invention is to provide a method for regenerating an ion exchange resin that can be saved and can save space.
[0009]
[Means for Solving the Problems]
The method for regenerating an ion exchange resin according to claim 1 of the present invention uses a regeneration facility comprising a cation exchange resin regeneration tower, an anion exchange resin regeneration tower, and a mixed ion exchange resin storage tank for circulation. An ion exchange resin regeneration method for regenerating a mixed ion exchange resin comprising a cation exchange resin and an anion exchange resin after use in an exchange tower, wherein the mixed bed ion exchange tower is used in the cation exchange resin regeneration tower. A step of backwashing the transferred mixed ion exchange resin into a cation exchange resin and an anion exchange resin, and a part of the anion exchange resin after the backwash separation in this step in the cation exchange resin regeneration tower After the transfer of the anion exchange resin to the anion exchange resin regeneration tower and the transfer of the anion exchange resin in this step, the circulating mixed ion exchange resin is transferred from the circulating mixed ion exchange resin storage tank to the positive ion. After transferring the mixed ion exchange resin for circulation to the on-exchange resin regeneration tower and in this step, the mixed ion-exchange resin is again converted into the cation exchange resin and the anion exchange resin in the cation exchange resin regeneration tower. And backwash separation in this step, after the backwash separation in this step, the step of transferring the remaining anion exchange resin from the cation exchange resin regeneration tower to the anion exchange resin regeneration tower, And a step of transferring the circulating mixed ion exchange resin from the cation exchange resin regeneration tower to the circulating mixed ion exchange resin storage tank after completion of the transfer of the anion exchange resin.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the embodiment shown in FIG. 1 to 4 are conceptual views of a regeneration facility showing an embodiment of the ion exchange resin regeneration method of the present invention in the order of steps.
For example, as shown in FIG. 1, a regeneration facility 10 used in the ion exchange resin regeneration method of the present embodiment includes a cation regeneration tower 11, an anion regeneration tower 12, a resin storage tank 13, a circulating resin storage tank 17, and transfer lines. 14, 15, 16, 18, and 19, and the equipment itself is configured by the same equipment as the conventional one, but the height of the cation regeneration tower 11 is lower than that of the conventional one.
[0011]
Then, the regeneration method of the ion exchange resin of this embodiment is demonstrated below. First, as shown by the arrows in FIG. 1, the mixed ion exchange resin after use is transferred from the mixed bed type ion exchange tower (not shown) into the cation regeneration tower 11 through the first transfer line 14. Next, when the mixed ion exchange resin is fluidized in the tower while supplying backwash water 50 from the bottom into the cation regeneration tower 11 as indicated by the arrow in the figure, the capacity expands to about twice. At the same time, the mixed ion exchange resin is separated due to the difference in specific gravity, the cation exchange resin is collected in the lower layer, and the anion exchange resin is collected in the upper layer. Thereafter, when the backwash water is stopped from flowing, the upper layer becomes an anion exchange resin A and the lower layer becomes a cation exchange resin K as shown in FIG. Is formed. Next, as shown by the arrow in FIG. 2, most of the anion exchange resin A is extracted from above the separation boundary surface S (for example, 250 mm above the separation boundary surface S) and regenerated through the second transfer line 15. When transferred into the column 12, the cation exchange resin mixed in the anion exchange resin near the upper portion of the separation boundary surface S remains in the cation regeneration column 11 without being extracted, and therefore remains in the anion regeneration column 12. As shown in FIG. 2, a substantially pure anion exchange resin A almost free of cation exchange resin K is transferred.
[0012]
Next, as shown by the arrows in FIG. 3, the circulating mixed ion exchange resin M is transferred from the circulating resin storage tank 17 into the cation regeneration tower 11 through the fourth transfer line 18 and the first transfer line 14. Even if the mixed ion exchange resin M for circulation is transferred in this way, most of the anion exchange resin has already been extracted from the cation regeneration tower 11, so the total amount of ion exchange resin in the cation regeneration tower 11 is initially Is equal to or less than the resin amount of the mixed ion exchange resin after use. In this state, as shown in FIG. 4, when the backwash water 50 is supplied from the bottom of the cation regeneration tower 11 and separated by backwashing, the anion exchange resin A ′ is gathered again in the upper layer and the cation exchange resin K is gathered in the lower layer. However, the height of the expanded resin layer at this time is equal to or lower than that of the expanded resin layer when the mixed ion exchange resin first transferred from the mixed bed ion exchange tower is backwashed and separated. After the backwashing and separation in this way, by calming down, a layer of anion exchange resin A ′ is formed in the upper layer as shown in FIG. 4, a layer of cation exchange resin K is formed in the lower layer, and at the boundary A new separation boundary surface S ′ is formed. This separation boundary surface S ′ is formed above the position of the separation boundary surface S in the case of FIG. 2 by the amount of newly added mixed ion exchange resin M for circulation. In other words, the layer of the anion exchange resin A ′ is also pushed upward from the case of FIG. 2, and the upper surface thereof is again positioned above the resin outlet of the second transfer line 15. Therefore, the anion exchange resin A ′ existing above the resin outlet is transferred into the anion regeneration tower 12 through the second transfer line 15 in the same manner as described above, and combined with the previous anion exchange resin, The same amount of anion exchange resin as that extracted from the mixed bed type ion exchange tower is secured in the anion regeneration tower 12. Subsequently, a small amount of anion exchange resin above the separation boundary surface S ′ and a small amount of cation exchange resin below the separation boundary surface S ′ remaining in the cation regeneration tower 11 are mixed for ion exchange for circulation. The resin (ion exchange resin located between the dotted lines above and below the separation boundary surface S ′ in FIG. 4) M is returned from the cation regeneration tower 11 to the circulating resin storage tank 17 through the fifth transfer line 19, Only the cation exchange resin K is left in the ion regeneration tower 11. The cation exchange resin at this time contains almost no anion exchange resin, and has the same capacity as the cation exchange resin initially extracted from the mixed bed ion exchange tower, and the mixture returned to the circulation resin storage tank 17. The amount of ion exchange resin M is also the same as when it was first received by the cation regeneration tower.
[0013]
Then, according to a conventional method, the cation exchange resin is regenerated with an acid regenerant such as hydrochloric acid or sulfuric acid in the cation regeneration tower 11, and the anion exchange resin is regenerated with an alkali regenerant such as sodium hydroxide in the anion regeneration tower. Since the anion exchange resin is hardly contained in the cation regeneration tower 11 and the cation exchange resin is hardly contained in the anion regeneration tower 12, the reverse regeneration phenomenon is caused in each of the regeneration towers 11 and 12. Will not occur. Therefore, the regenerated both ion exchange resins are transferred from the respective regeneration towers 11 and 12 to the resin storage tank 13 through the third transfer line 16 to prepare for reuse in the next mixed bed type ion exchange tower. Then, when regenerating the mixed ion exchange resin of the mixed bed ion exchange tower, the used mixed ion exchange resin is transferred from the mixed bed ion exchange tower into the cation regeneration tower 11 and emptied. The regenerated mixed ion exchange resin in the resin storage tank 13 is transferred into the mixed bed type ion exchange tower. Since this mixed ion exchange resin contains almost no reversely regenerated ion exchange resin, high-purity treated water can be obtained.
[0014]
As described above, according to the present embodiment, the mixed ion exchange resin after use is supplemented with the mixed ion exchange resin M for circulation, and the cation exchange resin K and the anion exchange resin A are backwashed and separated. In the method of regenerating ion exchange resins for individually regenerating the ion exchange resins K and A, the mixed ion exchange resin after use is backwashed and separated in the cation regeneration tower 11, and then the anion exchange is performed from the cation regeneration tower 11. Most of the resin A is transferred to the anion regeneration tower 12 to be removed, and then the mixed ion exchange resin M for circulation is replenished in the cation regeneration tower 11, and then the cation exchange resin K and the anion exchange resin A are replenished. Since the backwash separation was performed again, most of the anion exchange resin was already removed from the mixed ion exchange resin after use when adding the circulating mixed ion exchange resin and performing the backwash separation operation. The total amount of the ion exchange resin present in the cation regeneration tower 11 is low in comparison with the reproduction method. As a result, the backwash separation operation can be sufficiently performed even if the height of the cation regeneration tower 11 is lowered by the volume and expansion of the mixed ion exchange resin M for circulation compared with the conventional regeneration method, Therefore, space saving can be realized, and as a result, not only the construction cost of the cation regeneration tower 11 but also the construction cost incidental thereto can be reduced.
[0015]
Further, in this embodiment, the backwash separation transfer operation is performed in two stages, so that the separation performance of the mixed ion exchange resin is improved, and the reverse regeneration rate can be further reduced as compared with the prior art. The quality of the treated water by the ion exchange resin becomes higher than before, and a treated water with higher purity can be obtained.
[0016]
The present invention is not limited to the above-described embodiment, and after the mixed ion exchange resin to be regenerated in the cation regeneration tower is backwashed and separated, the anion exchange resin is extracted, and then the cation regeneration tower. Any operation in which a mixed ion exchange resin for circulation for preventing reverse regeneration is added therein and the mixed ion exchange resin is backwashed and separated again is included in the present invention.
[0017]
【The invention's effect】
According to the present invention, the height of the cation regeneration tower can be made lower than before, and the construction cost of the regeneration equipment can be reduced, and the reverse regeneration of the mixed ion exchange resin can be remarkably suppressed, and the space can be saved. It is possible to provide a method for regenerating an ion exchange resin that can be made simple.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a regeneration facility showing an embodiment of a method for regenerating an ion exchange resin according to the present invention in the order of steps, in which mixed ion exchange resin transferred from a mixed bed type ion exchange tower to a cation regeneration tower is shown. It is a figure which shows the state isolate | separated by backwashing.
FIG. 2 is a conceptual diagram of a regeneration facility showing a step that follows the step shown in FIG.
FIG. 3 is a conceptual diagram of a regeneration facility showing a step that follows the step shown in FIG. 2;
4 is a conceptual diagram of a regeneration facility showing a step that follows the step shown in FIG. 3. FIG.
FIG. 5 is a conceptual diagram showing a main part of a conventional regeneration facility.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Regeneration equipment 11 Cation regeneration tower 12 Anion regeneration tower 17 Circulating resin storage tank K Cation exchange resin A Anion exchange resin M Mixed ion exchange resin for circulation

Claims (1)

Using a cation exchange resin regeneration tower, an anion exchange resin regeneration tower, and a regeneration facility equipped with a mixed ion exchange resin storage tank for circulation, from a cation exchange resin and an anion exchange resin after use in a mixed bed ion exchange tower In the ion exchange resin regeneration method for regenerating the mixed ion exchange resin, the mixed ion exchange resin transferred from the mixed bed ion exchange tower in the cation exchange resin regeneration tower is converted into a cation exchange resin and an anion exchange resin. In this step, a part of the anion exchange resin after the backwash separation in this step is transferred from the cation exchange resin regeneration tower to the anion exchange resin regeneration tower, and in this step After the transfer of the anion exchange resin is completed, a step of transferring the mixed ion exchange resin for circulation from the circulation mixed ion exchange resin storage tank to the cation exchange resin regeneration tower, and a circulation in this step. After the completion of the transfer of the mixed ion exchange resin, the step of backwashing the mixed ion exchange resin again into the cation exchange resin and the anion exchange resin in the cation exchange resin regeneration tower, and after the backwash separation in this step The step of transferring the remaining anion exchange resin from the cation exchange resin regeneration tower to the anion exchange resin regeneration tower, and after the transfer of the anion exchange resin in this step, the cation exchange resin regeneration tower And a step of transferring the mixed ion exchange resin for circulation from the inside to the mixed ion exchange resin storage tank for circulation.

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