JPH0677687B2 - Regeneration method of ion exchange resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for regenerating an ion exchange resin, and by effectively removing a clad from an ion exchange resin contaminated by a condensate treatment, a recuperation after the regeneration is performed. The present invention relates to a regeneration method for improving the ability to remove suspended impurities during water treatment.

[Conventional technology]

In steam power generation equipment, the inside of the boiler must be kept clean at all times, so the condensate that flows into the boiler from the condenser is purified by a condensate demineralizer, and then highly purified before entering the boiler. Water is supplied as cooling water.

This condensate demineralizer is a so-called mixed bed desalting tower in which a cation exchange resin and an anion exchange resin are mixed and packed, and the ionic components and suspended solid components (mainly metal Oxide (commonly called clad) is removed by ion exchange, filtration and adsorption to purify condensate. Then, the ion component and the clad trapped in the ion exchange resin are separated from the ion exchange resin by the chemical regeneration in the regenerator of the condensate demineralizer and the physical washing operation by the backwash and removed from the system. Is discharged to. As a result, the ion exchange resin was cleaned and the ability to remove the ionic components and the clad was restored.

[Problems to be solved by the invention]

However, since the cleanliness of the clad required for cooling water into the boiler has been improved, the ion exchange resin is required to have a high clad removing ability. It only peels off the clad attached between, and in the chemical regeneration operation,
Since the current contact time with acid and alkali is as short as 1 to 2 hours, the clad adsorbed on the resin particle surface and the clad adsorbed inside the particle cannot be removed sufficiently, so the ion exchange resin is highly cleaned. However, the ability to adsorb the clad when passing water is too small to meet the demand for advanced clad removal.

The present inventor has made earnest studies in view of such a current situation and has conceived the present invention. The present invention is a method for regenerating an ion exchange resin capable of always maintaining the clad removing ability of the ion exchange resin at a high level. It is about.

[Means for solving problems]

The present invention relates to a method for regenerating a mixed resin of a granular cation exchange resin and an anion exchange resin which is contaminated by condensate treatment of a steam power plant, wherein the mixed resin is a cation exchange resin and an anion exchange resin. In the method for regenerating an ion exchange resin, the separated cation exchange resin is soaked in an acidic aqueous solution for 5 hours or more for regeneration, and the separated anion exchange resin is regenerated by a conventional method. is there.

In the present invention, as a means for separating a contaminated mixed resin of a cation exchange resin and an anion exchange resin into a cation exchange resin and an anion exchange resin, a means utilizing a difference in specific gravity is exemplified. However, it is not particularly limited.

Specifically, the cation exchange resin and the anion exchange resin are separated into two upper and lower layers (the cation exchange resin is the lower side and the anion exchange resin is the upper side) due to the difference in specific gravity due to the upper layer flow from the bottom.
The separated upper layer anion exchange resin is transferred to a separate column (anion exchange resin regeneration tower).

These separating means may be the same as or different from the means for regenerating the cation exchange resin in an acidic aqueous solution. Further, the separation process and the regeneration process may be intermittent or continuous. Further, the anion exchange resin separated by the separation treatment is usually treated with a NaOH solution.

As the cation exchange resin and the anion exchange resin used in the present invention, those known in the art can be used. Specific examples thereof include strong acid gel type or macroporous type cation exchange resin as the cation exchange resin, and strong acidic gel type or macroporous type anion exchange resin (I type) as the anion exchange resin. ) And the like.

In the present invention, the conventional regeneration method, that is, H ₂ SO ₄ having a concentration of about 8% injected from the upper portion of the resin layer in the cation exchange resin regeneration tower in a full state is transferred to the resin layer via the distribution nozzle. From the bottom to the bottom, comparing with the method that regeneration is performed during that,
Since it is in contact with the acidic aqueous solution for a long time, the resin particle surface is cleaned by efficiently removing and discharging the clad adsorbed on the resin particle surface or occluded inside the particle, and when the water is passed thereafter, the clad concentration becomes higher. It is possible to obtain high-purity water having a low purity. Further, as the acidic aqueous solution used as the regenerant of the cation exchange resin used at that time, an aqueous solution of sulfuric acid, hydrochloric acid, nitric acid or the like is suitable, and the concentration of those used is not particularly limited as long as it is 2% by weight or more. Considering the corrosion of the equipment due to acid and economical efficiency, a sufficient effect can be obtained by preferably adding 5 to 10% by weight.

(Operation) Hereinafter, the operation of the present invention will be described with reference to the drawings in comparison with the related art.

FIG. 1 shows the time of immersing the cation exchange resin in 8% by weight sulfuric acid on the horizontal axis and the amount of clad iron adsorbed on the surface on the vertical axis. According to this, the immersion time is lengthened. It can be seen that the amount of clad iron adsorbed decreases. About 8% concentration of H ₂ SO ₄ injected from the upper part of the resin layer in the conventional cation-exchange resin regeneration tower in a full water state flows from the top to the bottom of the resin layer via the distribution nozzle, and regeneration is performed during that time. In the chemical regeneration operation by the method, the time of contact with the acidic aqueous solution is about 1 to 2 hours because the conventional method was only intended to restore the ion exchange capacity. On the other hand, in the present invention, since the passage is stopped at the stage of being immersed in the acidic aqueous solution for the purpose of removing the clad that is difficult to dissolve and remove in a short time, the immersion can be performed for 5 hours or more. Since the amount of the clad desorbed from the cation exchange resin increases, the ability to remove suspended impurities during the condensate treatment after regeneration increases.

In the present invention, the immersion regeneration treatment is preferably performed for 10 to 15 hours in consideration of the ability to remove the clad adsorbed on the surface and problems in operation.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

FIG. 3 is a schematic cross-sectional view showing a specific example of a cation exchange resin regeneration treatment apparatus used in the present invention, wherein 1 is a scraping air valve, 2 is a backwash water valve, 3 is an acid inlet valve, 4 Is a freeboard drain valve, 5 is a freeboard drain pipe backwash air valve, 6 is an overflow valve, 7 is a wash water valve, 8 is a pressurized air valve, 9 is a vent valve, 10 is a drain drain valve, and 11 is a regeneration valve. A tower, 12 is an air and water supply pipe, 13 is an acid supply pipe, 14 is a freeboard drain pipe, and 15 is an overflow pipe.

The anion and cation exchange resins are separated from the contaminated resin by the difference in specific gravity, and the contaminated cation exchange resin suspended in water, that is, the slurry of the contaminated resin, is introduced into the regeneration tower 11, and the resin is lowered to a level below the acid supply pipe 13. To house. Next, the pressurized air valve 8 and the waste liquid drain valve 10 are opened and the other valves are fully closed to drain the water in the regeneration tower 11, the acid inlet valve 3 and the bend valve 9 are opened, and the other valves are fully closed. An acidic aqueous solution is supplied from the acid supply pipe 13 with the contaminated resin contained, and the contaminated resin is immersed. Then acid inlet valve 3
Store in a fully closed position. Predetermined time (5 hours or more,
After dipping for 10 to 15 hours) to remove the clad adsorbed on the contaminated resin from the acidic aqueous solution, the pressurized air valve 8 and the waste liquid drain valve 10 are opened and the other valves are fully closed to include the clad. The acidic aqueous solution, that is, the waste liquid is discharged. next,
After the bend valve 9 and the wash water valve 7 are opened and the other valves are fully closed to fill the regeneration tower 11 with water, the wash water valve 7 and the waste liquid drain valve 10 are opened and the other valves are fully closed to wash the resin. Wash the acid adhering to the. In this operation, when the clad contamination of the contaminated resin is significant, the effect can be improved by repeating the washing with the acidic aqueous solution a plurality of times.

Next, the cation exchange resin separated from the contaminated mixed resin is immersed and regenerated for 12 hours in the above regeneration treatment apparatus, and the anion exchange resin is treated by a conventional method in which an alkaline aqueous solution is passed downward for 1 hour. Then, a mixed resin composed of these both ion exchange resins was filled in a mixed bed desalting tower, and the transition of the clad iron concentration at the outlet of the mixed bed desalting tower during the condensate treatment after regeneration was measured. The results are shown in FIG.

For comparison, the same contaminated mixed resin as described above was regenerated after the regeneration in the same manner as above except that an acidic aqueous solution, which was the conventional chemical regeneration operation described above, was regenerated at a downward flow from the upper part of the resin layer for 1 hour. The transition of the clad iron concentration at the outlet of the mixed bed desalination tower during the condensate treatment was measured. This result is also shown in FIG.

From the above-mentioned Examples and Comparative Examples, it was confirmed that the reclaiming method of the present invention markedly improves the clad removing performance.

The apparatus shown in FIG. 3 is of the same type as the apparatus used for physical cleaning that is normally performed with pure water and air, and the present invention utilizes such existing cleaning equipment. It has the advantage of being extremely simple to implement.

〔The invention's effect〕

As described above, in the present invention, the ability to remove the clad with the ion exchange resin is remarkably excellent as compared with the prior art, so that the clad in the condensate can be highly purified by the condensate demineralizer. Therefore, the inside of the boiler can be always kept clean, and the soundness of the constituent equipment can be maintained.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the immersion time in an acidic aqueous solution and the amount of clad adsorbed on the surface of resin particles. The clad amount is shown by normalizing the surface adsorbed clad iron amount before immersion to 1. FIG. 2 is a graph showing the change over time in the clad iron concentration at the outlet of the desalting tower during the condensate treatment after regeneration of the contaminated mixed resin in the conventional comparative example and the example of the present invention.
The figure is a schematic sectional view showing a specific example of the apparatus used in the present invention. 1 ... Scraping air valve 2 ... Backwash water valve 3 ... Acid inlet valve 4 ... Freeboard drain valve 5 ... Freeboard drain pipe backwash air valve 6 ... Overflow valve 7 ... Wash water valve 8 ... Pressurized air valve 9 ... Vent valve 10 ... Waste liquid drain valve 11 ... Regeneration tower 12 ... Air and water supply pipe

Claims (2)

[Claims] 1. A method for regenerating a mixed resin of a granular cation exchange resin and an anion exchange resin, which is contaminated by condensate treatment of a steam power plant, wherein the mixed resin is a cation exchange resin and an anion exchange resin. And the separated cation exchange resin is immersed in an acidic aqueous solution for 5 hours or more for regeneration, and the separated anion exchange resin is regenerated by a conventional method. . 2. The method for regenerating an ion exchange resin according to claim 1, wherein the acidic aqueous solution is an aqueous solution of sulfuric acid, hydrochloric acid or nitric acid.