KR810000450B1 - Method for purifying water by continuous ion-exchanges - Google Patents

Abstract

Raw water was treated with an H-type weak acidic cation exchange resin to remove the bicarbonate and corresponding cations. Thus, the treated water was mixed with the two kinds of weak and strong basic anion exchange resin to make pure water in a continuous ion exchangers of mixed type.

Description

Process for producing pure water by interphase continuous ion exchanger

FIG. 1 shows an embodiment of the present invention, and illustrates a flow of a method for producing pure water by the mixed phase continuous ion exchange device of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing pure water using a mixed phase continuous ion exchanger, which significantly increases the amount of water treated by an ion exchange resin, prevents precipitation of calcium carbonate in the device, and regenerants. It is mainly aimed at the drastic improvement of the amount of the alkali which is used as a raw material.

The conventional method of producing pure water by a mixed phase continuous ion exchange device is a water column, in which a strong acid cation exchange resin and a strong base anion exchange resin are mixed to obtain pure water, and a resin having lost ion exchange ability is used. It is sent to a separation tower, where the amniotic resin is separated by backwashing, and the separated ion exchange resins are sent to the cation regeneration tower and the anion regeneration tower, and are regenerated with acid and alkali, and then returned to the water passage tower to continuously discharge water. How to get and repeat playback.

However, strong basic anion exchange resins, such as Anparaido® IRA-900 and Anparaido IRA-910, have strong exchange capacity for weak acids (H ₂ CO ₃ , H ₂ SiO ₃ ), The exchange capacity is small, and in particular, a decrease in the exchange capacity (especially a decrease in the neutral hydrolysis capacity) during use is large, and a regeneration efficiency is poor.

When raw water containing bicarbonate ions is passed through the water column of the mixed-phase continuous ion exchange device, a part of the slurry ion exchange resin in the lower portion of the water column is either an excess of anion exchange resin or salt type. In relation to the residual exchange capacity of the resin, the more the liquidity of the portion becomes the alkali side, the more difficultly soluble precipitates, such as calcium carbonate, precipitate and form near the bottom tower wall of the water tower or the water distributor, and further, the resin in the water tower. This can cause clogging, such as poor transfer of resin and poor resin fall, and impedes normal resin circulation in the continuous ion exchange device.

In the operation of the conventional mixed bed continuous ion exchange device, if a light blockage occurs, the operation of the device is stopped once, the blocked water passage and the negative ion regeneration tower are dismantled, and the problem is cleaned or the resin is removed. Since it was taken out of the tower and cleaned to remove poorly soluble deposits, it requires a great deal of effort and time in terms of maintenance and maintenance of the apparatus, which is a major obstacle in operation of the mixed phase continuous ion exchange apparatus. Such a phenomenon also occurs in an anion regeneration tower, and the same problem is a problem.

The present invention improves the drawbacks of the conventional method as described above. Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. It communicates with the weakly acidic cation exchange tower 8 installed in the water supply pipe.

In addition, the decarburization gas apparatus 1 communicates with the water flow tower of a mixed phase continuous ion exchanger by a water pipe.

The mixed-phase continuous ion exchange device is a well-known structure, and as shown in FIG. 1, the water supply tower 2 communicates with the separation tower 3 by the transfer pipe of the ion exchange resin, and the separation tower 3 is Each transfer pipe communicates with the cation regeneration tower 4 and the anion regeneration tower 5, and both regeneration towers 4 and 5 communicate with the water supply tower 2 by the transfer pipe. The water column 2 is filled with a strong acid cationic exchange resin and a mixture of a weakly basic anion exchange resin and a strong basic anion exchange resin as an anion exchange resin.

As a strong acid cation exchange resin, for example, Anparaido 200, etc. are used. As a weakly basic anion exchange resin, for example, Anparaido IRA-94, etc. are used. Use

Raw water is then introduced into the weakly acidic cation exchange column 8 and treated with an H-type weakly acidic cation exchange resin, such as Anparaido IRC-84, which is charged in the column, and the bicarbonate roots in the raw water and the divalent equivalents thereof. Remove the cation. That is, the H ⁺ weakly acidic cation exchange resin is not capable of decomposing neutral salts, but has a capacity of ion exchange from a weak acid salt to a corresponding cation, and has a very good regeneration efficiency.

Therefore, after treating with this cation exchange resin, the decarbonate treatment is carried out with the decarbonation gas apparatus 1 to completely remove the bicarbonate ions and to remove the corresponding cations in the order of high valence.

The water quality of the weakly acidic cation exchange resin and the treated water subjected to the decarbonation treatment is reduced in the salt content and further in the weak acid (bicarbonate) content. In the present invention, the treated water is passed to the water tower (2) of the mixed-phase continuous ion exchanger, but as described above, the weakly-anion exchange resin and the strong base anion exchange resin are used instead of the strong base anion exchange resin. Is charged. The treated water decarboxylated through the H-type weakly acidic cation exchange resin has less weak acid ions, and the optimum composition for use of the mixed anion exchange resin.

That is, the ratio of the weakly basic anion exchange resin with large ion exchange capacity and very good regeneration efficiency is increased, and only residual carbonic acid and silica remain as the load of the strong basic anion exchange resin, and the strong basic anion exchange resin has a small exchange capacity. The regeneration efficiency is not good, and the load factor for this is reduced, and the processing capacity of the anion exchange resin is greatly increased as a whole.

In addition, a part of the raw water flowing into the water tower (2) is used for the purpose of resin transfer to the separation tower (3) by using the resin below the distributor installed in the tower as a slurries. Ion exchange is carried out by passing through the resin layer of the tower | column part, and it flows out into the pure water tank 9 outside of a tower as pure water through the collector of a tower part.

Although the mixing ratio of the weakly basic anion exchange resin and the strong basic anion exchange resin in the water column 2 is appropriately determined depending on the composition of raw water, that is, the ratio of the amount of mineral ions and the amount of weak acid ions, it is usually one to one. There is much.

On the other hand, while obtaining pure water, the resin which lost ion exchange capacity of the lower part in the water supply tower 2 is continuously sent to the separation tower 3 via a conveying pipe, and the separation water is sent from the lower part of the separation tower 3 to it. The backwashing is carried out by upward flow, and the amniotic resin is separated using the specific gravity difference between the cation exchange resin and the anion exchange resin. The apparent specific gravity of the weakly basic anion exchange resin and the strong basic anion exchange resin is not a big difference but a mixed state.

Furthermore, the separated cation exchange resin is sent to the cation regeneration tower 4 and the anion regeneration tower 5 through the respective feed pipes at the top of the separation tower 3 at the bottom of the separation tower 3, respectively. An acid solution such as hydrochloric acid is passed through the acid tank 7 as a regenerating agent to the former, and an alkali solution such as caustic soda is passed through the alkali tank 6 as the regenerating agent to regenerate each resin.

In the separation column 3, when the cation exchange resin and the anion exchange resin are separated by a specific gravity difference, both are not completely separated according to various factors, and the cation exchange resin layer has an anion exchange resin on the anion exchange resin layer. The furnace is mixed with cation exchange resin.

Incorporation of the anion exchange resin into the cation exchange resin layer has little problem in the operation of the apparatus.

However, when the cation exchange resin is mixed into the anion exchange resin layer, when it is transported to the anion regeneration tower 5 and contacted with caustic soda, which is a regenerant, the conventional method shows that hardness components such as calcium and magnesium adsorbed on the cation exchange resin are Eluted with caustic soda, which reacts with carbonate or SiO ₂ in the regeneration waste liquid of the anion exchange resin, adheres to the screen portion of the regeneration waste liquid outlet of the anion regeneration tower 5 as a poorly soluble precipitate, However, this phenomenon is remarkable as the amount of cation exchange resin incorporated into the anion exchange resin layer increases and the concentration of HCO ₃ (bicarbonate ion) or Ca ^{++ in} the raw water increases.

However, in the present invention, as described above, since the carbonate component and polycation which are the causes of the formation of precipitates such as calcium carbonate are removed, the anion regeneration tower 5 is not blocked.

The regenerated ion exchange resin is sent to the water tower (2) by a transfer pipe from the lower part of each of the regeneration towers (4) and (5), and is supplied to the production of pure water in the tower, and then repeated. To prepare pure water continuously.

When the amount of bicarbonate ions in the raw water is smaller than the amount of photonic ions, the decarburization treatment as described above is not performed, and the raw water can be passed through the water tower 2 as it is.

The regeneration waste liquid regenerated from the ion exchange resin is discharged from the discharge pipes at the top of each regeneration tower (4) and (5), mixed with both waste liquids, and discharged after neutralization.

Compared with the manufacturing method of pure water by the mixed phase continuous ion exchange apparatus conventionally performed, this invention has the advantage shown below.

1. The amount of regenerant phosphate and alkali can be greatly reduced. The bicarbonate roots in the raw water are physically removed, and the corresponding cations are removed with a weakly acidic cation exchange resin having a very high regeneration efficiency. The regeneration waste liquid of the cation regeneration tower of the continuous ion exchange device can be used for this regeneration.

In addition, since the regeneration of the ion exchange resin in the production of pure water by the continuous ion exchange device is ideally possible to be regenerated, the use of the regeneration agent according to the conventional method is 1.3 for the strong acid cation exchange resin relative to the amount of ions in the raw water. -1.6 times, 1.6-2.2 times for type I strong basic anion exchange resin and 1.3-1.7 times for type II strong basic anion exchange resin.

In the present invention, in addition to using a weakly basic anion exchange resin having a high regeneration efficiency and a large exchange capacity, the present invention is changed by the mixing ratio of the weakly basic anion exchange resin. Regeneration can be drastically reduced by 1.3-1.6 times when mixing weakly basic anion exchange resin and 1.2-1.4 times when mixing with type II strong base anion exchange resin.

2. The treatment capacity of ion exchange resin can be greatly improved.

The weak basic anion exchange resin has a low exchange capacity for weak acids, but has a high exchange capacity as an anion exchange resin, and further, a decrease in the exchange capacity during use is less than that of a strong basic anion exchange resin.

On the other hand, strong basic anion exchange resins have a low exchange capacity, but use a mixture of weakly basic anion exchange resins and strong basic anion exchange resins as anion exchange resins in the water column, and reduce the amount of weak acid ions in the raw water by pretreatment. Thereby reducing the load of the strong basic anion exchange resin having a low exchange capacity, and carefully combining the advantages of the respective anion exchange resins to impose this portion on the weakly basic anion exchange resin having a large exchange capacity. It is possible to achieve the maximum capability and to further increase the production efficiency of pure water.

In addition, in the present invention, since the strong basic anion exchange resin is mixed with the strong basic anion exchange resin as described above, the physical strength of the weakly basic anion exchange resin is stronger than the strong basic anion exchange resin, and the exchange capacity reduction rate is also lower. With less, the amount of ion exchange resin replenishment can be reduced.

3. It is possible to prevent clogging of the continuous ion exchanger.

In the present invention, the bicarbonate ions in the raw water, which is the source of the precipitate, are almost removed, and most of the hardness components are also removed at the front end. Blockages due to can be completely prevented.

4. The amount of recycled waste is reduced, and waste treatment is simplified because the recycled waste does not contain hard components and carbonate ions. Most of the hardness components in the raw water are adsorbed on the H type weakly acidic cation exchange resin and can be removed as chloride during regeneration. The regeneration waste liquid of the continuous ion exchange device reduces the amount of regenerant because the amount of the inlet ion decreases and the regeneration efficiency of the anion exchange resin becomes good.

Furthermore, since the anion exchange resin regeneration waste liquid does not contain carbonate, it is possible to save acid other than neutralization, and does not produce precipitation of calcium carbonate, and does not block the neutralization tank and piping.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described.

The raw water of the composition shown in the following 1st table | surface was processed by the fixed bed type resin tower which filled Anparaido IRC-84 as H type weakly acidic cation exchange resin, and further this is decarbonated by the well-known decarbonation gas apparatus. The treatment was the same as in the first table below. In the resin tower and the decarbonation gas apparatus, the treatment conditions may be ordinary conditions.

TABLE 1

Next, the raw water or decarbonated water was treated with the following four types of mixed phase continuous ion exchangers (A)-(D) under normal conditions. Quantity, amount of regenerant).

Conventional method

(A) The raw water shown in the first table is treated with Anparaido 200 as a strong acid cation exchange resin and Anparaido IRA-910 as a strong basic anion exchange resin, without treating the H type weakly acidic cation exchange resin and decarboxylation. When treated with the used mixed phase continuous ion exchanger.

(B) H type weakly acidic cation exchange resin and decarbonated treated water shown in Table 1 are treated with a mixed phase continuous ion exchanger using Anparaido 200 and Anparaido IRA-910.

Invention method

(C) Type H weakly acidic cation exchange resin and treated water treated with decarbonization in Table 1 are Anparaido 200, anhydrous IRA-94 as weakly basic anion exchange resin, and strong base anion exchange resin. When treated with a mixed phase continuous ion exchanger using a mixture of Paraido IRA-900 (1 to 1).

(D) Mixtures of H-type weakly acidic cation exchange resins and decarbonated treated water shown in Table 1 with Anparaido 200, Anparaido IRA-94, and Anparaido IRA-910 (1: 1) When treated with a mixed bed continuous ion exchanger.

TABLE 2

The case of (b) was set to 1, and (a), (c), and (d) were compared by ratio.

In the case of (c) and (d) above, that is, the method of the present invention is superior in all respects to the others.

In addition, what was shown in the 3rd table | surface was used for the regeneration agent ratio (equivalent ratio of regeneration agent with respect to target ion amount) of the ion exchange resin used in the present Example.

TABLE 3

Regarding the treatment of regenerated waste liquid, raw water from the first table is used, and the result of processing 1 m 3 of raw water by the methods (a), (b), (c) and (d) is shown in Table 4.

TABLE 4

⁺⁺ M represents total mine.

The method of (C) and (D) which becomes this invention from the said result is the most excellent.

Claims (1)

Raw water is treated with an H-type weakly acidic cation exchange resin to remove bicarbonate roots and corresponding cations in the raw water, followed by decarbonate treatment to reduce the weak acid component, and the decarbonated water is treated with a cation exchange resin and an anion. A method of producing pure water, characterized by passing through a mixed phase continuous ion exchange device using a mixture of a weakly basic anion exchange resin and a strong basic anion exchange resin as an exchange resin.

Images