JPH0254137B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for backwashing and separating used packing materials in a packed tower that uses two or more types of packing materials with different specific gravities. In addition to reliably and completely transferring the top layer of packed material to other columns, it also effectively removes fine fillers and impurities in the surface layer after backwashing in packed towers using single or multiple packing materials. The present invention relates to a method for separating and transporting filler for removal.

In general, there are many examples in which fluids are treated by filling them with fillers, and various types of fillers such as sand, anthracite, activated carbon, and ion exchange resins are used singly or in combination. When using a plurality of materials, as is well known, they may be used in a layered manner or in a mixed manner. Although the scope of the present invention is not limited by the type of filler and the filling state of the filler, an example in which an ion exchange resin is used will be explained here.

[Prior art]

Desalination tower (hereinafter referred to as MB), cation regeneration tower (hereinafter referred to as CRT), anion regeneration tower (hereinafter referred to as ART)
Conventionally, in condensate desalination equipment consisting of a resin storage tank (hereinafter referred to as RST) and a resin storage tank (hereinafter referred to as RST), a strongly acidic cation exchange resin (hereinafter referred to as SAR) and a strong basic anion exchange resin (hereinafter referred to as SBR) are used. The resin is mixed and filled into the MB to treat the condensate, but when the regeneration period is reached, the resin is transferred from the MB to the CRT.
In CRT, SAR and SBR are backwashed and separated into lower layer SAR and upper layer SBR using the difference in specific gravity.
Transfer SBR to ART. Then add acid to the CRT.
SAR and SBR are regenerated by passing alkali through ART. Both recycled resins are transported to RST, mixed, and used again in MB as needed.

By the way, with the recent spread of supercritical pressure boilers and nuclear power generation boilers, increasingly sophisticated water quality management is required, and the performance of condensate desalination equipment has to be improved.

For example, in supercritical pressure boilers,
It has been operated in a state where SAR's H type and SBR's OH type are mixed, the so-called H-OH cycle.
There are many examples of operation using the so-called ammonia cycle, in which condensate is treated even after the SAR exceeds the ammonia added to the condensate. The biggest problem when treating condensate with this ammonia cycle is that when transitioning from the H-OH cycle to the ammonia cycle, Na ⁺ leaks out according to the reaction formula: R-Na + NH ₄ OH → R-NH ₄ + Na ⁺ . The problem was that the water supply limit value was no longer satisfied, but not only that, but also due to the high condensate pH, water was removed from the resin layer of the MB.
Another major problem is that anions such as Cl ^- or SO ^2- ₄ tend to leak out. The leakage of these impurity ions is due to the presence of Na type SAR and Cl type or _SO ^2-4 type SBR in the mixed resin layer after regeneration.

Na-type SAR excluding abnormal situations such as seawater leaks
is generated because SAR mixed in ART comes into contact with caustic soda, which is a regenerant. This problem has been solved by patent No. 1027750, etc., which makes it possible to reliably and stably suppress the proportion of Na-type SAR to 0.05% or less of the total SAR without using any special regenerating agent.

Except for seawater leaks, the causes of generation of Cl type or SO ^2- ₄ type SBR are (1) insufficient separation and transportation;
(2) Contact of SBR remaining in the CRT with hydrochloric acid or sulfuric acid, which is a regenerating agent; (2) Contact with salt, etc. contained in caustic soda, which is a regenerating agent for SBR;
There are two reasons. Among these, cause (2) can be solved to some extent by using caustic soda produced by a manufacturing method such as the ion exchange membrane method, but (1)
The cause of this has not yet been fully resolved.

Here, when using the conventional resin separation method,
Indicating the status of the SBR remaining in the CRT, the first
As shown in Figures 2 and 3.

The shaded area in Figure 1 shows the water collection pipe 2, resin transfer pipe 3, and drug delivery pipe 4 when transferring resin from MB to CRT1.
The mixed resin deposited at the top of the CRT 1 is not affected by the backwash flow from the bottom of the CRT1 and often remains even after backwash separation. Then, backwash water is introduced from the bottom of CRT1 to slightly expand the SAR layer and perform SAR.
The SBR and a portion of the SAR are transferred to the ART through a resin transfer pipe 3 installed below the separation interface between the SBR and the SBR.

However, in such a separation and transfer method, SBR remains on the surface layer of the resin layer of the CRT 1 even after SBR transfer is completed, as shown by the hatched area in FIGS. 2 and 3, and complete transfer is not possible. FIG. 2 shows a side view of the SBR after it has been transferred by the conventional method, and FIG. 3 shows a top view. The layer height l of SBR in FIG. 2 can be as high as 20 to 30 mm, and the residual amount of SBR may be 4 to 5% of the total SBR.

In this way, the opening of the resin transfer pipe 3 is set to SAR.
Even though it was installed below the SBR separation interface.
As a result of research, it was found that the reason why SBR remains as shown in Figures 2 and 3 is due to the following reasons.

(1) When backwash water is introduced and the SAR layer is transferred with a slight expansion, the distance d between the opening of the resin transfer pipe 3 and the surface layer of the resin layer, the distance L between this opening and the tower wall, and the distance mentioned above during transfer. It has been found that there is a region of the surface layer of the resin layer that easily enters the opening, and that this region is extremely narrow, and that the above is largely related to the above.

(2) In other words, the closer the SBR is to the tower wall, the longer it takes to reach the opening.

(3) The force of sucking (transferring) the resin at the opening is strongest directly below the opening, and this force suddenly weakens as the resin moves away from directly below. Regarding the resin directly below the opening, SBR is transferred first, but SAR below it is also transferred.
In other words, by the time the SBR far from the opening reaches the opening, the SAR directly below the opening is transferred, so if the amount of backwash water introduced does not change, d will gradually increase, and the SBR far from the opening will be further removed from the opening. This makes it difficult to reach and transport. When d reaches a certain value, the SBR directly below the opening will no longer be transferred and will remain as shown in FIG.

As shown in FIG. 4, there is a method in which the opening of the transfer pipe is a straight pipe 5 that crosses the tower and a slit 5' is cut, but this drawback still remains. Furthermore, even if the amount of backwash water is increased to reduce the above d, the residual amount of SBR will be reduced, but the amount of SAR transferred will be considerably large, and at the same time, SAR will be transferred in proportion to the amount of backwash water, and at a certain level d. When the limit is reached, the SBR will no longer be transferred.

[Purpose of the invention]

The present invention aims to provide a rational separation and transfer method for ion exchange resins that does not have the above-mentioned conventional drawbacks, and is based on the facts explained by the present inventor with reference to FIGS. 1 to 4 above. This was completed as a result of intensive research in light of the problems.

[Structure of the invention]

In a packed tower using two or more types of packing materials with different specific gravities, the present invention is capable of backwashing and separating used packing materials, and then transferring the top layer of packing materials to another column from the bottom of the packed tower. While introducing backwash water and slightly backwashing and expanding the filler in the lower layer than the top layer, the filler in the top layer is removed above the separation interface between the filler in the top layer and the filler in the adjacent lower layer. This method is characterized in that the filler in the uppermost layer is separated and transferred while giving a swirling flow to the filler.

An ion exchange tower using an ion exchange resin as a filler according to the present invention will be described below with reference to FIGS. 5 to 8.

In the present invention, when transferring the upper layer SBR that has been backwashed and separated in the CRT, backwash water is introduced from the bottom of the CRT and the backwash development rate of the lower layer SAR is preferably 10% or less, while the resin separation interface is A liquid or gaseous swirling medium is introduced from above.
Transfer is performed while giving a swirling flow to the SBR, but in this case, if the backwash development rate of the SAR in the lower layer is increased, the swirling flow may cause the SAR to partially swirl as well as the SBR, resulting in a large amount of SAR. There is a risk that the materials may be transferred. To avoid this, the flow rate of backwash water should be LV6m/h or less, preferably LV2~4m/h, so that the SAR backwashing development rate is 10% or less.
Alternatively, a distributor for SBR transfer may be provided slightly below the resin separation interface. With this method, there is no risk of large amounts of SAR being transferred, so the flow rate of backwash water should be from LV10 to
It can be made quite large at 25m/h.

By giving such a swirling flow, deposits are deposited in the water collection pipe 2, drug delivery pipe 4, resin transfer pipe 3, etc., and the CRT
Resin that remained unsettled even by backwash water from the bottom fell down due to horizontal flow, and furthermore, with conventional transfer methods, it remained on the surface of the SAR.
As shown in Fig. 5, the SBR moves from the tower wall toward the center of the tower by the swirling flow generated by the introduction of water, air, etc. from the swirling flow introduction pipe 6, and opens near the center. More than 99.9% of the total anion resin is reliably transferred from the opening 7 of the resin transfer tube 3, and almost no SBR remains in the CRT 1.
Moreover, even when the resin is transferred while giving a swirling flow as described above, the backwash water is introduced from the bottom of the column, so there is no unevenness on the surface layer of the SAR.
The SBR is transported smoothly and reliably to the center of the tower.

The backwash water is used to ensure that the SBR is smoothly transported toward the center of the tower and to prevent unevenness from occurring on the surface layer of the SAR.
Excessive backwashing of SAR must be avoided.

By this method, as shown in Figure 5,
SBR gathers in the center of the tower in a spiral shape due to swirling flow.
In the center, the SBR soars to a fairly high position. In such a state, if all the water above the opening 7 of the resin transfer tube 3 is transferred by pressurization using air pressure, the SBR can be almost completely separated and transferred.

As a result, SBR does not come into contact with acid during the resin regeneration process, and therefore leakage of impurity anions during condensate treatment can be appropriately prevented. In addition, the opening 7 of the resin transfer pipe 3 is positioned above the separation interface between SAR and SBR.
Preferably, by positioning it at a position 20 to 100 mm above the separation interface, the amount of SAR mixed in when SBR is transferred to ART can be almost eliminated. As a result, the conventional transfer method had the disadvantage that the resin balance was easily lost, but the present invention can also overcome this disadvantage.

In addition to the above effects, if the method of the present invention is applied to ART, there is an advantage that the leakage of Na ⁺ can be further reduced as described below.

In other words, in the conventional method, the
SBR contains a large amount of SAR, but conventionally only the upper layer of SBR, which is backwashed and separated in the presence of excess SBR in ART, can be regenerated and used for condensate desalination. It is being done. However, with this method, most of the SAR settles to the bottom of the ART and does not cause problems;
Some SAR has a sedimentation rate similar to that of SBR, so although the amount of SAR is extremely small, SAR
It will be mixed into the layer. When this fine SAR comes into contact with caustic soda, which is a regenerating agent, it turns into Na form and is added to the treated water during condensate treatment using an ammonia cycle.Although this is a problem in the range of 0.3ppb as Na or less, it is a cause of extremely small amounts of Na ⁺ leakage. Become.

Fine SAR mixed in the SBR layer by the inventor
A detailed investigation of the distribution of SAR on several actual devices revealed that a relatively large amount of fine SAR exists in the 10 to 20 mm surface layer of the SBR, and the amount is greater than that in the surface layer.
It is 3 to 6 times larger than the part below 20 mm. Therefore, the SBR and a portion of the SAR transferred to the ART are backwashed in the presence of excess SBR, and then the method of the present invention is applied to transfer and remove the surface layer portion of the SBR while giving a swirling flow. This makes it possible to extremely reduce the amount of fine SAR that gets mixed into the SBR layer and causes Na ⁺ leakage. Also,
Since fine SBR is also removed at the same time, the differential pressure of water passing through the MB can also be reduced.

Next, an example of an embodiment of the present invention will be explained in detail with reference to the drawings. In Figure 6, the used mixed resin that has undergone condensation treatment in the MB passes through the resin transfer pipe 8.
Transferred to CRT1. In the CRT 1, the backwash valve 9 and air wiping valve 10 are opened to fill the resin layer with water.
Furthermore, the backwash valve 9 is closed and the wash water valve 11 is opened.
Fill the CRT with water.

Next, the swirl flow introduction valve 6' attached to the swirl flow introduction pipe 6 and the backwash drain valve 12 are opened to generate a swirl flow.
The resin deposited on the water collection branch pipes, supports, manhole attachment parts, etc. of the water collection pipe 2 during transfer is removed by swirling flow. Then, the backwash valve 9 and the backwash drain valve 12 are opened and backwash separation is performed at a flow rate of LV10 to 20m/h, which is normally performed, and the lower layer SAR13 and the upper layer are separated.
Separate into two layers of SBR14.

When backwash separation is completed, backwash water introduction valve 1 for transfer
5. Open the backwash drain valve 12 and introduce backwash water for transfer at LV2 to 4 m/h so that the SAR backwash development rate in the lower layer is 10% or less, and keep the SAR backwash development rate constant. keep. After opening the swirling flow introduction valve 6' to generate a swirling flow, the resin transfer valve 3' attached to the resin transfer pipe 3 is opened, the backwash drain valve 12 is closed, and the air valve 16 is opened to apply pressure. While using SBR14 as ART1
Transfer to 7.

The swirling flow introduction pipe 6 may have its opening 6'' directed in the circumferential direction concentric with the inner wall of the CRT 1, as shown in FIGS. 7 and 8, for example, but it is not limited to this. In Figures 7 and 8, the swirling flow introduction pipe 6 is installed at only one location, but if the column diameter is large, it may be installed at two or three locations.In addition, the installation location should be determined so as not to disturb the SAR layer 13. to make
It is preferable that the opening 6'' be installed 300 to 400 mm or more above the separation interface between SAR and SBR, and that the direction of the opening 6'' be inclined at 5 to 15 degrees with respect to the horizontal plane and directed upward.

The flow velocity of the swirling flow is 0.05 to 0.3 at the tower wall.
The opening diameter of the swirling flow introduction pipe is set so that m/sec.
It is best to determine the flow rate.

When the separation and transfer of the SBR 14 is completed, air scrubbing is performed to remove SS, and then the regenerant inflow valve 18 and the regenerant outflow valve 19 are opened to allow the regenerant, hydrochloric acid or sulfuric acid, to pass through. The drug delivery device inside the CRT1 is not shown, but it is installed near the center of the CRT1.
The installation height should be set so that it does not interfere with the swirling flow.
Next, the SAR 13 that has been extruded and washed and regenerated is transferred to the RST (not shown) via the resin transfer pipe 20. On the other hand, the SBR 14 transferred to the ART 17 is backwashed by opening the backwash valve 21 and the backwash drain valve 22 in the presence of excess SBR. During this process, some SAR23 brought in during transfer settles to the bottom of ART17. After scrubbing and backwashing the resin above the water collection pipe 24, the valve 2 of the swirling flow introduction pipe 25 installed above the surface layer of the SBR 14
5' and the valve 26' of the fine resin transfer pipe 26 are opened to provide a swirling flow while transferring and removing the SBR and fine SAR on the surface layer.

This step of removing fine resin does not need to be performed every cycle, but once every several dozen cycles, the amount of Na ⁺ leakage and
This can be done as appropriate while paying attention to the increase in the differential pressure of MB.

The medicine is passed by opening the regenerating agent inflow valve 27, the valve 28 attached to the water collection pipe 24, and the pressurized water introduction valve 29, and then extrusion and washing are performed. Next, the amount used for condensate desalination of the regenerated SBR14 in the upper part of the water collection pipe 24 is 600 to 1000 from the surface layer of SAR23.
The resin is transferred to the RST in a known manner via a resin transfer pipe 30 located at a distance of mm above the water collection pipe 24 and slightly above the water collection pipe 24. In RST, the previously transported SAR and SBR are mixed and reused in the MB.

By doing this, the recycled mixed resin contains
Almost no Na-type SAR and Cl-type or SO ^2-4 _- type SBR are contained, so treated water of extremely high purity can be obtained.

In addition, when the packed tower is filled with three or more types of fillers, the uppermost layer of the filler may be transferred to the outside of the column using the above method, and then the lower layer of filler may be sequentially transferred using the same method.

〔Effect of the invention〕

As described above, if the present invention is applied to condensate desalination, it will be possible to sufficiently meet the demands for advanced water quality control with a simple device and simple operation. The invention is applicable to various types of packed towers that use fillers other than ion exchange resins, and the separation and transfer of fillers can be carried out accurately, thus preventing impure fillers from entering the packed tower. This has the advantage of significantly improving the performance of the packed column and significantly streamlining its operation and maintenance.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a CRT showing the residual state of the mixed resin, and Figures 2 and 3 are vertical cross-sectional views of a CRT showing the residual state of the strong basic anion exchange resin on the surface layer of the strongly acidic cation exchange resin. and a plan view, FIG. 4a is a vertical sectional view showing an example of a resin transfer tube of a conventional CRT, and FIG. 4b is a - of FIG. 4a.
5 to 8 show one embodiment of the present invention; FIG. 5 is a longitudinal sectional view of the CRT during the transfer of strongly basic anion exchange resin in a swirling flow; FIG. 6 is a longitudinal sectional view of the CRT; is a flow sheet showing the resin separation and transfer process,
FIGS. 7 and 8 are plan views showing different specific examples of the shape and arrangement of the swirling flow introduction tube provided in the CRT. 1...CRT, 2...Water collection pipe, 3...Resin transfer pipe, 3'...Resin transfer valve, 4...Medication pipe, 5...
Straight pipe, 5'...slit, 6... swirling flow introduction pipe,
6'...Swirling flow introduction valve, 6''...Opening, 7...Opening, 8...Resin transfer pipe, 9...Backwash valve, 10...
...Air vent valve, 11...Washing water valve, 12...Backwash drain valve, 13...SAR, 14...SBR, 15...
...Backwash water introduction valve, 16...Air valve, 17...
ART, 18... Regenerant inflow valve, 19... Regenerant outflow valve, 20... Resin transfer pipe, 21... Backwash valve,
22...Backwash drain valve, 23...SAR, 24...
Water collection pipe, 25... swirling flow introduction pipe, 25'... valve,
26... Fine resin transfer pipe, 26'... Valve, 27...
... Regenerant inflow valve, 28 ... Valve, 29 ... Pressurized water introduction valve, 30 ... Resin transfer pipe.

Claims (1)

[Claims] 1. In a packed tower filled with two or three or more types of fillers having different specific gravities, after these fillers are backwashed and separated, the fillers in the uppermost packed bed are A method for transferring a packing material, characterized in that the filling material is transferred to the outside of the packed tower while giving a swirling flow to the filling material and simultaneously introducing backwash water from a position below the packed bed. 2 The introduction flow rate of the backwash water during the transfer of the filler material is set to a value such that the backwash expansion rate of the filler in the uppermost packed layer and the adjacent packed layer is 10% or less. The method described in Scope 1. 3. A patent claim in which the operation of imparting a swirling flow to the packing material is performed by introducing water in the circumferential direction of the inner wall surface of the packed column above the separation interface between the uppermost packed bed and the adjacent packed bed. The method according to item 1 or 2 of the scope. 4. Claims in which the filler is transferred via a resin transfer pipe having an opening above the separation interface between the uppermost packed bed and the adjacent packed bed and near the center of the packed tower. The method according to item 1, item 2, or item 3. 5. Any one of claims 1 to 4, wherein the packing material used in the packed tower is of a single type or a plurality of types, and the portion to be transferred after backwashing is a surface layer portion of the packing material or impurities. or the method described in one section.