JP2940648B2 - Pure water production equipment - Google Patents

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, it eliminates the conventional backwashing, shortens the resin regeneration time, and makes the ion exchange tower smaller and simpler.

[0002]

2. Description of the Related Art Pure water from which all salts and free weak acids and silicic acids in raw water have been removed requires high-pressure boiler feed water, process water, electronics industry 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 using an ion exchange resin, and in fact, a combination of a cation exchange column filled with a cation exchange resin and an anion exchange column filled with an anion exchange resin, or further a decarbonation column A double-bed manufacturing apparatus is used. In this double-bed apparatus, there are various methods depending on the flow direction of raw water in the tower and the flow direction of the regenerating chemicals of the ion-exchange resin. And the raw water flows downward through the tower.
Downstream water systems are known. This is because there are advantages such as a higher regeneration efficiency and a smaller amount of regenerated chemicals, as compared with a method in which both regeneration and water flow are performed in a downward flow.

[0003]

In a conventional ion exchange tower, suspended substances (hereinafter referred to as "turbidity") of the raw water accumulate in the resin layer due to the flow of the raw water. A backwash must be performed to remove the turbidity in the column.

[0004] For this backwashing, a considerably large space (hereinafter referred to as a free board) is required above the filled resin tower. For example, in the anion exchange tower, the height of the free board needs to be about 60% or more of the height of the anion exchange resin layer, and in the cation exchange tower, the height of the free board also needs to be about 60% or more. Was needed. For this reason, the total height of these exchange towers is considerably large, and there have been problems such as an increase in production costs and an increase in the size of the installation building.

In the upward flow regeneration, in order to prevent the ion exchange resin layer from being pushed up and flowing by the upward flow of the regenerant, the regenerant is introduced from a distributor installed at the lower part in the exchange tower and ionized. A method of discharging from a collector installed above the exchange resin layer is adopted. Further, at the time of regeneration, water or air is caused to flow in from the upper portion of the free board, and the resin layer is pressed and held by the inflow pressure of the water or air to prevent fluidization thereof. Such distributors are special in order to uniformly disperse the regenerant and prevent fluidization of the resin layer during regeneration, and the collectors are also special for uniform liquid collection. The cost of building the tower was increasing.

In order to solve this problem, a conventional backwash tower is provided above the exchange tower, and the backwash tower and the exchange tower are connected to each other by a communication pipe. The method of discharging from is adopted. However, in this case, a backwash tower is required, and the problems of manufacturing cost and installation space still remain.

Further, in such an upflow regeneration / downflow water purification method, 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 water flow ( (R-H) or OH type anion exchange resin (R-OH) is disturbed, so that the residual R-
There is a problem that the effective use of H, R-OH is not performed, and the above-mentioned advantages of the method are lost.

[0008]

According to the present invention, as a result of various studies, a pure water producing apparatus comprising an ion exchange tower which does not require the above-mentioned freeboard or backwash tower has been developed.

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 decarbonation tower and an anion exchange tower, which is disposed upstream of the pure water production apparatus. In addition, a membrane separation device is installed to suppress the inflow of turbid matter into the cation exchange tower and the anion exchange tower. A strong acidic cation exchange resin is used in the cation exchange tower, and a strong basic anion is used in the anion exchange tower. The exchange resin is filled in the space inside each exchange tower without any gaps by providing an expansion allowance for the regeneration swelling of each exchange resin at the top, and the raw water pretreated by the above membrane separation device is exchanged. It is characterized in that the backwashing step is omitted by treating in a resin tower by an upflow regeneration / downflow water system.

The turbid substance is, for example, clay, hydroxides, organic substances, wood chips and other foreign substances. As the above-mentioned membrane separation device, a reverse osmosis membrane device, an ultrafiltration membrane device or a microfilter (microfiltration membrane device) is effective.

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

As described above, since the membrane separation device for suppressing the inflow of turbid matter is installed at the preceding stage of the pure water production device, it is not necessary to perform the backwash, and the regeneration time can be reduced. . In addition, since the conventional backwash tower and free board can be eliminated, the height of the tower can be reduced, and the production cost can be reduced.

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

A flexible porous membrane, for example, two sheets having a large number of small holes, which is in contact with the top surface of the ion exchange resin filled in the column and can be expanded in accordance with swelling during regeneration of the ion exchange resin. Between the rubber plates, a material such as a Saran cloth having openings that allow the liquid to pass but not allow the ion-exchange resin to pass is provided and bonded, and the ion-exchange resin layer is pressed by the flexible porous membrane. Well,
By doing so, fluidization of the resin layer during regeneration can be more reliably prevented.

[0015]

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

[0016]Cation component Anion component  Na + K = 23.5mgCaCO_Three/ Liter HCO_Three= 35.6mgCaCO_Three/ Liter Ca = 34.8 〃 SO_Four = 15.0 〃Mg = 23.2〃 Cl = 26.1 〃 total cations = 81.5NO ₃ = 4.8 〃 Salt constituent total anion = 81.5 ＣＯ CO_Two = 14.3 〃SiO ₂ = 15.7〃 Total anion = 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]Cation component Anion component  Na + K = 1.9 mgCaCO_Three/ Liter HCO_Three= 1.5 mgCaCO_Three/ Liter Ca = 0.3〃SO_Four = 0.2 〃Mg = 0.2〃 Cl = 0.4 〃 Total cation = 2.4NO ₃ = 0.3〃 Salt composition total anion = 2.4 ＣＯ CO_Two = 5.0 〃SiO ₂ = 1.4〃 Total anion = 8.8 〃

The permeated water thus obtained is passed through a double-bed pure water production 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 known eye plate (3) (4) having a structure in which the liquid passes through the height positions shown in the figures in the towers (1) and (2) but does not allow the ion exchange resin to pass therethrough
During this time, Amberlite IR-124 was used as a strongly acidic cation exchange resin (5) in the cation exchange column (1).
100 liters (based on Na type), 300 liters (based on Cl type) of Amberlite IRA-410 as a strongly basic anion exchange resin (6) were charged into the anion exchange column (2), In addition, an exchange tower was used in which a height of expansion allowance (7) in consideration of the amount of regenerated swelling of these resins was provided between the upper panel (3) and the top surface of the filled resin.

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

[0021]Play conditions  (1) Cation exchange tower ・ Regeneration agent 3% hydrochloric acid ・ Regeneration level 35% HCl 150g / liter-R ・ Regeneration process (water sampling completed) → HCl passage (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 100 g / liter-R • Regeneration step (water sampling completed) → NaOH passing (LV = 15 m / H, 15 minutes) → extrusion (LV = 15m / H: 20 minutes) → Washing (20 minutes) ・ Regeneration time: 55 minutes

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

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

[0025]

[Table 1]

[0026]

As described above, according to the present invention, the number of steps for regeneration of the ion exchange resin and the time required for the regeneration can be greatly reduced as compared with the prior art. The required water usage is also greatly reduced.

Also, there is no need for any internal components such as distributors and collectors, which are conventionally required. The exchange tower has a simple structure and the height of the tower is higher than that of the conventional apparatus by eliminating the free board for backwashing. Can greatly reduce the production cost as well as simplifying the structure.

Further, according to the present invention, since backwashing is not performed at the time of regeneration, the RH or R-OH layer which remains unreacted at the bottom of the tower at the end of water flow can be effectively used without disturbing the layer. Accordingly, the electrical resistivity of the obtained treated water is also extremely high in purity as compared with the conventional method.

[Brief description of the drawings]

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cation exchange tower 2 Anion exchange tower 3 Face plate 4 Face plate 5 Strongly acidic cation exchange resin 6 Strongly basic anion exchange resin 7 Expansion margin height

Continuation of the front page (72) Inventor Miwa Shimizu 1-4-9, Kawagishi, Toda City, Saitama Prefecture Inside the Organo Research Institute (56) References JP-A-58-159852 (JP, A) JP-A-63- 205145 (JP, A) Japanese Patent Publication No. 4-11273 (JP, B2) Jiko 58-2432 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) C02F 1/42 B01J 47 / 02-47/08 B01J 49/00-49/02

Claims (4)

(57) [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 decarbonation tower and an anion exchange tower,
In front of the pure water production device, a membrane separation device for preventing the inflow of turbid matter into the cation exchange column and the anion exchange column is installed, and the strongly acidic cation exchange resin is anion-exchanged in the cation exchange column. The column is filled with a strong basic anion exchange resin in the space inside each exchange column, with a sufficient expansion allowance for the regenerated swelling of each exchange resin at the top, without any gaps, and pre-filled with the above membrane separator. A pure water production apparatus characterized in that the treated raw water is treated in each of the exchange resin towers by an upflow regeneration / downflow water system to omit the backwashing step. 2. The pure water production apparatus according to claim 1, wherein the membrane separation device is a reverse osmosis membrane device, an ultrafiltration membrane device, or a microfilter. 3. The expansion allowance according to claim 1 corresponds to a regeneration expansion height of each filled resin provided between a mesh plate fixed on an upper part of the tower and a top surface of the filled resin. Pure water production equipment. 4. The pure water production apparatus according to claim 1, wherein the expansion allowance corresponds to an allowable expansion of a flexible porous membrane provided in contact with a top surface of the exchange resin.