JPS5892463A - Regeneration of ion-exchange apparatus - Google Patents

Abstract

PURPOSE:To perform regeneration effective in raising the electroconductivity of treated water after the regeneration, by separating and regenerating resins, subjecting the resins to a separating-regenerating step again, and then regenerating one part of the resin. CONSTITUTION:In regenerating both of cation- and anion-exchange resins in a mixed bed-type ion-exchange apparatus, water is supplied through a lower drain pipe 9 to separate the cation- and anion-exchange resins, a chemical liquid and balance water are injected through a pipe 9 and a chemical liquid-injecting pipe 7 to regenerate the resins, the resins are backwashed again with water, and then one of the anion- and cation-exchange resins is regenerated. Since the resin converted into a type-Cl or -Na by the first injection of the chemical liquid is separated and regenerated by the next backwashing, the electroconductivity of treated water after the regeneration can be enhanced, and a time for washing can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regenerating a mixed bed type ion exchange device using a negative and positive ion exchange resin.

In a mixed bed type ion exchange device that uses both anion and positive ion exchange resins in a mixed state, both ion exchange resins are separated and regenerated by backwashing, mixed, and then subjected to water flow. The drawing is a vertical cross-sectional view showing a state in which the resin of a mixed bed type ion exchange device is separated, and 1 is an ion exchange column, and 2 is this ion exchange column 1.
3 is an anion exchange resin bed formed in the upper part; 4 is a water collecting plate that supports these resins; 5 is a strainer provided on the water collecting plate 4;
1 is an intermediate drainage pipe provided between both resin beds, 7 is a chemical injection pipe provided above the resin bed, 8 is an upper water supply and drainage pipe, 9 is a lower water supply and drainage pipe, and 10 is a gas discharge pipe. In the mixed bed type ion exchange equipment as described above, water is supplied from the upper water supply and drainage pipe 8 in a state where both resins are mixed, ion exchange is performed, ion exchange water is obtained from the lower water supply and drainage pipe 9, and ion exchange water is obtained by quantitative water sampling or quantitative water sampling. Move on to the regeneration process.

Conventional regeneration methods for such mixed bed ion exchange equipment are generally as follows.

■Water backwashing: Water is supplied from the lower water supply and drainage pipe 9 and the upper water supply and drainage pipe 8
The resin is expanded and fluidized by upward flowing water to relax the resin bed, and the suspended solids trapped in the resin bed are also discharged, and at the same time, the negative and positive ion exchange resins are separated due to the difference in specific gravity.

■Stopping: By completely stopping the movement of water in the ion exchange tower 1, both separated resins are allowed to settle as they are, with the cation exchange resin bed 2 at the bottom and the cation exchange resin bed 6 at the top, as shown in the drawing. form.

■Medicine note: 2 to 3 drops of 5 to 10% hydrochloric acid from the lower water supply and drainage pipe 9
A/, e-resin is supplied, and the drug injection pipe 7
The cation exchange resin bed 2 is regenerated by supplying two lances of water and discharging the regenerated waste liquid from the intermediate drain pipe 6.

When this is completed, 4 to 5% sodium hydroxide is supplied from the chemical injection pipe 7 with 2~'') A/A-resin, balance water is supplied from the lower water supply and drainage pipe 9, and recycled waste liquid is discharged from the intermediate drainage pipe 6. is discharged to regenerate the anion exchange resin bed 6.The order of the above drugs may be reversed, or the drugs may be injected at the same time.

■Extrusion: Even after chemical injection is completed, extrusion water is supplied from the chemical injection pipe 7 and lower water supply/drainage pipe 9 at the same flow rate as the chemical or balance water during chemical injection for a certain period of time, and is drained from the intermediate drain pipe 6 to resin. Push the regeneration agent out of the floor.

■Drainage: Drain water to the top of the resin floor.

■Mixing: Compressed air is supplied from the lower water supply and drainage pipe 9, discharged from the gas discharge pipe 10, and the yin-yang exchange resin is mixed. In addition to compressed air, an inert gas (such as nitrogen) may also be used for mixing.

■Suspension: Stop supplying compressed air, etc. and form a mixed resin bed.

■ Water is supplied from the water supply and drainage pipe 8 above the water filling port, and air is discharged from the gas discharge pipe 10 to fill the ion exchange tower 1 with water.

■Cleaning: Similar to the water sampling process, water is supplied from the upper water supply and drainage pipe 8, and water is drained from the lower water supply and drainage pipe 9, and the resin bed is washed until the water quality reaches a predetermined value.

After completing the regeneration of the resin as described above, the water sampling process is started again, and ion exchange is performed in the same manner as described above.

In the conventional regeneration method as described above, some anion exchange resin becomes Cj form due to hydrochloric acid, which is a regenerant for cation exchange resin, during regeneration, and this resin is hydrolyzed during water passage after regeneration. C! There was a problem that ions were released and the conductivity of the treated water deteriorated.

The same thing happens with cation exchange resins, and some of the cation exchange resins become Na-form due to IJium (hydroxide), which is a regenerating agent for anion exchange resins, and this resin is This is a problem that sometimes releases Na ions and deteriorates the conductivity of treated water.

This invention was made in order to solve the problems of the conventional method as described above. After the resin is separated and regenerated, a bulk separation step is added to regenerate one of the resins, thereby improving the conductivity of the treated water after regeneration. It is an object of the present invention to provide a method for regenerating an ion exchange device that can increase the efficiency.

This invention is a method for regenerating anion exchange resins in mixed bed type ion exchange equipment. This is a method for regenerating an ion exchange device, characterized in that only one of the ion exchange resins is regenerated by chemical injection.

Examples of anion exchange resins that are converted into Cj form by hydrochloric acid during chemical injection regeneration are as follows.

- Due to a defect in the water collection and distribution structure, water remains in the dead soot near the water collection plate 4 and strainer 5 without being able to be separated even by backwashing.

■Things that remain in the cation exchange resin bed 2 due to causes such as dullness or large particle size.

■If the separation surface of the onion tube ion exchange device is lower than the intermediate drain pipe 6, the one located at that lower part.

Further, as cation exchange resins that can be converted into Na form with sodium hydroxide, there are the following.

- Items that remain in the anion exchange resin bed 6 due to dirt and small particle size.

0 If the separation surface of both resins is higher than the intermediate drain pipe 6, the one located at the higher part.

Most of the above Cj-form or Na-form resins are separated into respective resin beds by backwashing again. This is because the resin remaining in the drain is replaced with other resin by backwashing and mixing. Therefore, if you perform backwashing again to separate the resins and regenerate only one resin by chemical injection, that resin will be completely regenerated, and no ions will be released into the treated water after regeneration. , can increase the conductivity of treated water.

Which resin to regenerate depends on the required water quality, resin stability, amount of resin, etc., and should be decided according to each situation, but anion exchange resins tend to deteriorate easily. Since it is preferable to use all of its exchange capacity, it is desirable to regenerate the anion exchange resin again.

When the anion exchange resin is to be regenerated again, the anion exchange resin that has become CI type during chemical injection is collected into the upper anion exchange resin bed 6 by backwashing, and then regenerated with sodium hydroxide. By CI! / shape to OH shape, thereby preventing water decomposition at the cutting edge.

A single resin particle is completely C! If it takes shape, R-CA
In the equilibrium reaction of +HzO;--R-OR+HC#, R-(J
A part of it is hydrolyzed and C! Although ions are released, hydrolysis stops when a portion of the single particle is converted to the OH form. Therefore, the amount of IJ hydroxide used for the second time may be small. The above performance is also the same when regenerating the cation exchange resin.

The regeneration method of the present invention performs a separation step and one of the chemical injection regenerations after the chemical injection regeneration according to the conventional method, and these steps can be performed after the completion of either of the steps ① to ③ in the conventional method. However, it is particularly desirable to perform this after the completion of step 0. In this case, the following step is inserted between steps 2 and 3 of the conventional method.

■Water backwashing: Same as ■ above ■Pause: Same as ■ above.

■Chemical Note: Regenerate either the anion exchange resin or the cation exchange resin. In either case, the procedure is the same as in the above (■), but the amount of regenerant used is 1/'5 and 1/1, respectively.
0 is fine.

■Extrusion: Same as above (■) for recycled resin.

[F] Draining: Same as above (■).

[F] Mixing: Same as above (■).

■ Pause: Same as above.

After performing the above process, perform the process of ■■ of the conventional method,
End playback.

By performing regeneration as described above, the resin converted into Cj form or Na form by the first chemical injection will be separated by the next backwashing, so it will be regenerated, and it will not be hydrolyzed in the water flow process. The conductivity of the treated water will not deteriorate. In order to separate the Cj-type or N&-type resin remaining in other resin beds by arrow backwashing, it is better to perform the mixing step (2). This is because the resin remaining near the strainer can be replaced by air blowing.

As described above, according to the present invention, by adding a separation step again to regenerate one of the resins after separation and regeneration of the resin, it is possible to increase the conductivity of the treated water after regeneration with a simple operation. Cleaning time can be shortened. It also has the advantage that it can be used even with degraded anion exchange resins or weakly basic anion exchange resins that have been hydrolyzed.

Next, examples and comparative examples of the present invention will be described.

Comparative Example 1 100% of cation exchange resin Diaion 5KIB (trademark of Mitsubishi Chemical Industries, Ltd.) was placed in an ion exchange column 1 with a diameter of 60 Crn and a height of 2 m. , anion exchange resin Diaion PA
416 to 200! It was filled, ion exchanged, and the next regeneration was performed.

■Water backwash, 1 minute/'hr, 15 minutes.

■Pause: 5 minutes.

■Medicine injection: 4% sodium hydroxide in a downward flow of 1000A/
hr, 5% hydrochloric acid was passed simultaneously at an upward flow of 5007/hr for 30 minutes.

■Extrusion: Downward flow of pure water 100 (] #/hr, Upward flow 50
Fluid was passed at 0 p/hr for 30 minutes at the same time.

■Drainage: ■Mixing: Air blowing for 5 minutes.

■Pause: 5 minutes.

■Full of water: 5 minutes.

■Cleaning: 3/hr0 Example 1 The following process was inserted between 00 and 00 of Comparative Example L.

■Water backwashing: Same as ■.

■Pause: Same as ■.

■Raku'PE: 4% hydroxide) Downward flow of IJum 100
Z/hr, pure water was passed at an upward flow of 500 A/hr for 5 minutes at the same time.

■Extrusion: Same as ■ above.

[F] Draining: Same as above (■).

[F] Mixing: Same as above (■).

■ Pause: Same as above.

Comparative Example 2 In Comparative Example 1, the amount of cation exchange resin filled was 120!
, the filling amount of the anion exchange resin was set to 180, and the cation exchange resin bed 109 was backwashed and separated! Regeneration was carried out under the same conditions as in Comparative Example 1, except that an intermediate drain pipe was provided at the position of , and the cation exchange resin in the upper part 20e was changed to Na form in the regeneration process.

Example 2 In the above Example 1, the chemical injection of
/hr, 5% hydrochloric acid upward flow 500 /3/hr
Regeneration was carried out by inserting an additional step under the same conditions as in Example 1 between 0 and 0 of Comparative Example 2, except that the liquid was passed for 5 minutes at the same time.

Table 1 shows the relationship between washing time and purity in Comparative Example 1.2 and Example 1.2.

Table 1 Purity of cleaning wastewater (MΩ-crrL)

[Brief explanation of the drawing]

The drawing is a vertical sectional view showing a mixed bed ion exchange device.
1 is an ion exchange column, 2 is a cation exchange resin bed, and 6 is an anion exchange resin bed. Agent: Patent Attorney Sei Yanagihara

Claims (3)

[Claims] (1) When regenerating both the anion exchange resin and the anion exchange resin in a mixed bed type ion exchange device, after separating the both ion exchange resin and regenerating the chemical injection, a separation process is added again, and then the anion exchange resin or the cation exchange resin is regenerated. A method for regenerating an ion exchange device, characterized in that only one of the ion exchange resins is regenerated by chemical injection. (2) The method for regenerating an ion exchange device according to claim 1, wherein the anion exchange resin is regenerated again. (3) A method for regenerating an ion exchange device according to claim 1, wherein the cation exchange resin is regenerated again.