JPH05138161A - Demineralizer - Google Patents

Abstract

PURPOSE:To unnecissitate backwash and to reduce regeneration time by installing a membrane separation device for preventing the inflow of turbid components in the first part of a demineralizer. CONSTITUTION:In the first part of a demineralizer is installed a membrane separation device for preventing the turbid components from flowing in a cation exchange tower and an anion exchange tower. The cation exchange tower and the anion exchange tower are closely packed with strong acidic cation exchange resin and strong basic anion exchange resin at their space parts with a height of expansion allowance for the exchange resin swelled on regeneration being left in their upper parts respectively. And raw water pretreated by the membrane separation device is treated in each exchange tower with an upflow regeneration/downflow passage system. Thereby since there is no backflow, the number of regeneration processes for ion exchange resin and the time required for regeneration are reduced and since freeboard for backwash is not provided, the height of the unit is reduced to lower manufacturing cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing pure water,
In particular, the conventional backwash is eliminated to shorten the resin regeneration time, and the ion exchange column is made small and simple.

[0002]

2. Description of the Related Art Pure water from which salts, free weak acids, hydrochloric acid, etc. in raw water have all been removed requires high-pressure boiler feed water, process water, electronic industrial water, nuclear reactor water, and other highly pure water. Widely used as process water and test / research water. And such pure water is usually produced by using an ion exchange resin, and actually, a cation exchange column filled with a cation exchange resin and an anion exchange column filled with an anion exchange resin, or a decarboxylation column is further combined. A multi-bed manufacturing device is used. In this multi-bed apparatus, there are various methods depending on the direction of raw water in the tower and the direction of the regenerated chemicals of the ion exchange resin. The raw water flows through the tower, and the raw water flows downward in the tower.
The descending circulating water system is known. This is because it has advantages such as high regeneration efficiency and a small amount of regenerated chemicals, as compared with a system in which both regeneration and water flow are performed in a downward flow.

[0003]

In the conventional ion exchange tower, suspended solids of raw water (hereinafter referred to as turbidity) accumulate in the resin layer due to the passage of raw water, so that the first step of the regeneration process is Backwashing must be carried out to remove the suspended matter in the tower.

For this backwashing, a considerably large space (hereinafter referred to as a freeboard) was required above the filled resin column. For example, in the anion resin tower, the height of the freeboard needs to be about 60% or more of the height of the anion exchange resin layer, and in the cation exchange tower, about 60% or more of the height of the cation exchange resin layer. Was needed. For this reason, the total height of these exchange towers becomes quite large, and there are problems such as an increase in production costs and an increase in the size of the installation building.

In addition, in the above-described upflow regeneration, in order to prevent the exchange resin layer from being pushed up and flowing by the upflow of the regenerant, the regenerant is introduced from a distributor installed in the lower part of the exchange tower to exchange the exchange resin. The method of discharging from the collector installed in the upper part of the layer is adopted. Further, at the time of regeneration, water or air is made to flow in from the upper part of the freeboard, and the resin layer is pressed and held by the inflow pressure of the water or air to prevent its fluidization. Such a distributor is a special one to evenly disperse the regenerant and prevent fluidization of the resin layer during regeneration, and the collector is also a special one for uniform liquid collection. It was pushing up the manufacturing cost of the tower.

In order to solve this, a conventional dedicated backwash tower is installed above the exchange tower, and the backwash tower and the exchange tower are connected by a communication pipe to remove the suspended matter above the backwash tower. The method of discharging from is adopted. However, in this case as well, a backwash tower is required, and the problems of manufacturing cost and installation space still remain.

Further, in such pure water production of the up-flow regeneration / down-flow water system, if backwashing is carried out during regeneration, the H-type cation exchange resin remaining unreacted at the bottom of the tower at the end of the water passage ( R-H) or an OH type anion exchange resin (R-OH) layer is disturbed, so that the residual R-
There is a problem in that H and R-OH are not effectively used, and the advantages of the method are lost.

[0008]

As a result of various studies in view of this, the present invention has developed a pure water producing apparatus comprising an ion exchange column which does not require the above freeboard or backwash column.

That is, the apparatus of the present invention is a pure water production apparatus comprising a cation exchange tower and an anion exchange tower, or a pure water production apparatus comprising a cation exchange tower, a decarboxylation tower and an anion exchange tower, and the preceding stage of the pure water production apparatus A membrane separator to prevent the inflow of suspended solids into the cation exchange column and the anion exchange column, a strong acid cation exchange resin is used for the cation exchange column, and a strong basic anion is used for the anion exchange column. The exchange resin is filled in the space in each exchange tower with a high expansion margin corresponding to the amount of regenerated swelling of each exchange resin without any gap, and the raw water pretreated by the above-mentioned membrane separation device is exchanged for each exchange. It is characterized in that the backwashing step is omitted by treating the resin tower with the upflow regeneration / downflow water system.

The suspended matter is, for example, clay, hydroxides, organic matter, wood chips and other foreign substances. A reverse osmosis membrane device, an ultrafiltration membrane device, or a microfilter (microfiltration membrane device) is effective as the membrane separation device.

The above-mentioned expansion margin is the swelling amount of each filled resin at the time of regeneration (that is, the swelling amount when changing from Na type to H type in the case of cation exchange resin, and also of the anion exchange resin). In this case, the volume corresponding to the swelling amount when changing from Cl type to OH type) is converted to the height of each exchange column. For example, in a cation exchange column packed with Amberlite (registered trademark) IR-124 as the strongly acidic cation exchange resin, this margin is about 3.5% of the packed height of the Na-type cation exchange resin, and In the anion exchange column packed with Amberlite IRA-402 as the basic anion exchange resin, it is about 10% of the filling height of the Cl type anion exchange resin.

Since the membrane separator for suppressing the inflow of suspended matter is installed in the preceding stage of the pure water producing apparatus as described above, it is not necessary to carry out backwashing and the regeneration time can be reduced. .. Further, since the conventional backwash tower and freeboard can be eliminated, the tower height can be reduced, and therefore the manufacturing cost can be reduced.

Further, since the above-mentioned free board is eliminated and the space in each exchange tower is filled with the ion exchange resin with its expansion allowance at the top without any gaps, for example, the upper and lower eye plates are provided inside the tower. In the case of a device that is installed and filled with an ion exchange resin between these two eye plates, the resin layer can be easily pressed against the upper eye plate by letting the regenerant flow in at an upward flow that is slightly faster than the normal flow speed. Therefore, the resin layer does not flow. Therefore, conventional collectors and distributors are not required, and the tower structure is simple.

A flexible porous membrane which is in contact with the top surface of the ion-exchange resin packed in the tower and can expand according to the swelling of the ion-exchange resin during regeneration, for example, two sheets having a large number of small holes. Between the rubber plates, there is provided a material which is sandwiched and adhered with a cloth such as a rag cloth having an opening that does not allow the ion exchange resin to pass through, and the ion exchange resin layer is pressed by the flexible porous membrane. Well,
This makes it possible to more reliably prevent fluidization of the resin layer during regeneration.

[0015]

EXAMPLES Next, examples of the present invention will be described. (Example) Raw water of a water quality containing the following cations and anions was treated in order with an ordinary coagulating sedimentation apparatus, a filter and a decarbonation tower.

[0016]Cationic component Anion component  Na + K = 23.5mgCaCO₃/ Liter HCO₃= 35.6mgCaCO₃/ Liter Ca = 34.8〃 SO_Four = 15.0 〃Mg = 23.2〃 Cl = 26.1 〃 Total cations = 81.5 〃NO ₃ = 4.8 〃 Salt composition All anions = 81.5 〃 CO₂ = 14.3〃SiO ₂ = 15.7 〃 Total anions = 111.5 〃

Thereafter, the treated water was treated with a reverse osmosis membrane device equipped with a reverse osmosis membrane (NTR-759HR, manufactured by Nitto Denko Corporation) to obtain permeated water having the following water quality.

[0018]Cationic component Anion component  Na + K = 1.9 mg CaCO₃/ Liter HCO₃= 1.5 mg CaCO₃/ Liter Ca = 0.3〃 SO_Four = 0.2 〃Mg = 0.2 〃 Cl = 0.4 〃 Total cations = 2.4 〃NO ₃ = 0.3 〃 Salt composition All anions = 2.4 〃 CO₂ = 5.0 〃SiO ₂ = 1.4 〃 Total anions = 8.8 〃

The permeated water thus obtained is passed through a multi-bed type pure water producing apparatus comprising a cation exchange column (1) as shown in FIG. 1 and an anion exchange column (2) as shown in FIG. Watered That is, a well-known eye plate (3) (4) of a structure that allows liquid to pass through but not ion exchange resin at the height positions shown in the figures in the towers (1) and (2)
Amberlite IR-124 was installed as a strongly acidic cation exchange resin (5) in the cation exchange tower (1) during this period.
To 100 liters (Na type standard), and the anion exchange column (2) was charged with 300 liters (Cl type standard) of Amberlite IRA-410 as a strongly basic anion exchange resin (6). In addition, an exchange tower was used in which an expansion margin height (7) in consideration of the amount of regenerated and swelled resin was provided between the upper eye plate (3) and the top surface of the packed resin.

Flow rates of 50 m / H and 13 m / H (hereinafter LV) are applied to the cation exchange column and the anion exchange column, respectively.
The above-mentioned permeated water was passed through in a downward flow, and the exchange resin was regenerated in an upward flow under the following conditions to produce pure water. As a result, it was possible to stably produce pure water having a specific resistance of 16 MΩ-cm or more when passing water.

[0021]Playback condition  (1) Cation exchange tower ・ Regenerant 3% hydrochloric acid ・ Regeneration level 35% HCl 150g / liter-R ・ Regeneration process (water collection end) → HCl replenishment (LV = 16m / H, 10 minutes)
→ Extrusion (LV = 16m / H: 15 minutes) → Washing (20 minutes) ・ Regeneration time: 45 minutes

(2) Anion exchange tower-Regenerant 3.0% caustic soda-Regeneration level 100% NaOH 100g / liter-R-Regeneration process (end of water sampling)-> NaOH feed (LV = 15m / H, 15 minutes)-> Extrusion (LV = 15m / H: 20 minutes) → Washing (20 minutes) ・ Regeneration time: 55 minutes

(Conventional example) On the other hand, in the conventional downflow / upflow regeneration multi-bed type pure water production apparatus in which backwashing is performed in the regeneration step, the regeneration step and regeneration at the same regeneration level as in the above embodiment The required time is shown in Table 1 below.

When regeneration was performed under the conditions shown in Table 1 and pure water was produced by passing permeated water at the same flow rate as in the example, the specific resistance of the obtained treated water was 3 to. 5 MΩ
-cm, which was of extremely low purity as compared with the case of the device of the present invention.

[0025]

[Table 1]

[0026]

As described above, according to the present invention, it is possible to significantly reduce both the number of steps and the time required for the regeneration of the ion exchange resin as compared with the prior art, and further, the regeneration is accompanied by this. The amount of water used will also be greatly reduced.

Further, no internal components such as a distributor and a collector which are conventionally required are required, the exchange tower has a simple structure, and the freeboard for backwashing is eliminated, so that the tower height is higher than that of the conventional apparatus. Since it has been possible to lower the manufacturing cost, it contributes greatly to the simplification of the structure and the reduction of the manufacturing cost.

Further, according to the present invention, since backwashing is not carried out at the time of regeneration, at the end of the passage of water, the layers of RH and R-OH which remain unreacted at the bottom of the tower can be effectively used as they are without disturbing. Therefore, the electric resistivity of the obtained treated water is also extremely higher than that of the conventional method.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a filling height of a resin in a cation exchange tower according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a filling height of resin in an anion exchange column according to an embodiment of the present invention.

[Explanation of symbols]

 1 Cation exchange tower 2 Anion exchange tower 3rd plate 4th plate 5 Strongly acidic cation exchange resin 6 Strongly basic anion exchange resin 7 Expansion margin

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 6, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art Pure water from which salts, free weak acids, silicic acid, etc. in raw water are all removed requires high-pressure boiler feed water, process water, electronic industrial water, reactor water, and other highly pure water. Widely used as process water and test / research water. And such pure water is usually produced by using an ion exchange resin, and actually, a cation exchange column filled with a cation exchange resin and an anion exchange column filled with an anion exchange resin, or a decarboxylation column is further combined. A multi-bed manufacturing device is used. In this multi-bed apparatus, there are various methods depending on the direction of raw water in the tower and the direction of the regenerated chemicals of the ion exchange resin. The raw water flows through the tower, and the raw water flows downward in the tower.
The descending circulating water system is known. This is because it has advantages such as high regeneration efficiency and a small amount of regenerated chemicals, as compared with a system in which both regeneration and water flow are performed in a downward flow.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

For this backwashing, a considerably large space (hereinafter referred to as a freeboard) was required above the filled resin column. For example, in the anion exchange tower, the height of the freeboard needs to be about 60% or more of the height of the anion exchange resin layer, and in the cation exchange tower, about 60% or more of the height of the cation exchange resin layer. Was needed. For this reason, the total height of these exchange towers becomes quite large, and there are problems such as an increase in production costs and an increase in the size of the installation building.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

Further, in the above-described upflow regeneration, in order to prevent the ion exchange resin layer from being pushed up and flowing due to the upflow of the regenerant, the regenerant is introduced from a distributor installed in the lower part of the exchange tower to generate ions. The method of discharging from the collector installed above the exchange resin layer is adopted. Further, at the time of regeneration, water or air is made to flow in from the upper part of the freeboard, and the resin layer is pressed and held by the inflow pressure of the water or air to prevent its fluidization. Such a distributor is a special one to evenly disperse the regenerant and prevent fluidization of the resin layer during regeneration, and the collector is also a special one for uniform liquid collection. It was pushing up the manufacturing cost of the tower.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

A flexible porous membrane which is in contact with the top surface of the ion-exchange resin packed in the tower and can expand according to the swelling of the ion-exchange resin during regeneration, for example, two sheets having a large number of small holes. Between the rubber plates, a piece of Saran cloth or the like having an opening that allows liquid to pass but not ion exchange resin to pass is sandwiched and adhered, and the flexible porous membrane holds down the ion exchange resin layer. Well,
This makes it possible to more reliably prevent fluidization of the resin layer during regeneration.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

The permeated water is passed through the cation exchange column and the anion exchange column at a flow rate of 50 m / H and 13 m / H (hereinafter referred to as LV), respectively, under the following conditions. Pure water was produced by regenerating the ion exchange resin in an upward flow. As a result, the specific resistance is 16 when passing water.
Pure water of MΩ-cm or more could be stably manufactured.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Miwa Shimizu 1-4-9 Kawagishi, Toda City, Saitama Organo Research Institute

Claims (4)

[Claims] 1. A pure water production apparatus comprising a cation exchange tower and an anion exchange tower, or a pure water production apparatus comprising a cation exchange tower, a decarboxylation tower and an anion exchange tower,
A membrane separator for suppressing the inflow of suspended solids into the cation exchange tower and the anion exchange tower is installed in the preceding stage of the pure water producing apparatus, and a strong acid cation exchange resin and anion exchange resin are installed in the cation exchange tower. The columns were filled with strong basic anion exchange resin in the space inside each exchange column with a high expansion margin for the regenerated and swollen portion of each exchange resin at the top without any gaps, and the space was reserved by the membrane separation device described above. A pure water producing apparatus characterized in that the backwashing step is omitted by treating the treated raw water in each exchange resin tower by an upflow regeneration / downflow circulating water method. 2. A pure water producing device, wherein the membrane separation device according to claim 1 is a reverse osmosis membrane device, an ultrafiltration membrane device or a microfilter. 3. The expansion margin according to claim 1 corresponds to the regenerated expansion height of each filled resin provided between the eye plate fixed to the upper part of the tower and the top surface of the filled resin. Pure water production equipment. 4. The pure water production apparatus according to claim 1, wherein the expansion allowance is equivalent to the allowable expansion height of the flexible porous membrane provided in contact with the top surface of the exchange resin.