JP5738505B2 - Method for filling a filler containing an ion exchanger - Google Patents

Description

  The present invention relates to a method for filling an electric regenerative desalination apparatus with a filler containing an ion exchanger. In particular, the present invention relates to a method for filling a desalting chamber or a concentration chamber of an electric regeneration type desalting apparatus with a filler having ion exchange performance such as an ion exchanger.

  Conventionally, as an apparatus for producing ultrapure water, an electroregenerative desalination apparatus characterized by filling an ion exchanger into a desalination chamber or a concentration chamber is disclosed in Japanese Patent Publication No. 4-72567 and US Pat. No. 4,632,745. And U.S. Pat. No. 3,330,750 (concentration chamber filling by IONICS). These apparatuses are required that the filled ion exchangers are uniformly filled in the respective chambers and that there is no space in which the flow of the liquid is short-passed.

  However, it is generally difficult to charge the ion exchanger uniformly and without gaps in a plurality of desalting chambers and concentration chambers of an electric regeneration type desalting apparatus. As a method for supplying the bead-shaped ion exchanger filled in the electric regenerative desalting (hereinafter referred to as EDI) device to each desalting chamber, there are various methods before or during assembly of the electrodialysis tank for the desalting device. A method of filling every time and a method of filling from a common duct for supplying a liquid after assembling or a nozzle dedicated to filling of an ion exchanger are generally known.

  However, in the method of filling each pair, there is a problem that the structure of the chamber frame becomes complicated due to unitization, and the assembly takes time when the number of pairs of electrodialysis tanks increases. On the other hand, in the method of filling from a common duct or a nozzle dedicated to filling of the ion exchanger, the supply time to each chamber such as a desalting chamber is shortened, but not only the structure of the chamber frame is complicated, but each chamber There is a problem that it is difficult to control the filling degree of the ion exchanger in and the confirmation of the filling amount is difficult.

  Furthermore, the upper limit of the amount of ion exchanger that can be filled is at most about the normal close-packed packing (space ratio = 0.636) or less, so in order to prevent a short path of the liquid, The direction of movement must be downflow. For this reason, there exists a problem that the countermeasure against degassing in a desalination chamber system and the liquid retention countermeasure at the time of a stop are needed separately.

  On the other hand, as shown in Japanese Patent Laid-Open No. 9-253458, which is characterized by preventing a short path in the desalination chamber, the filler containing the ion exchange resin is volume-contracted by drying or other means and then packed. It is possible to swell the filling material after assembling the electrodialysis tank and swell the filler, and to fill the desalting chamber of the dialysis tank without gaps. However, in this method, the volume change of the packed body before and after swelling is too large. Then, there is a possibility that the ion exchange membrane separating the desalting chamber during the swelling of the packing body is dragged by the packing body to cause damage.

Problems to be solved by the invention

  Accordingly, an object of the present invention is to provide a filling technique of a filler having ion exchange performance such as an ion exchanger that can avoid the occurrence of the above-described problems. That is, the present invention prevents the generation of a space in which a liquid flow may short-pass from the inlet to the outlet when a liquid is passed through a chamber such as a desalination chamber filled with a filler, and a plurality of chambers. At the same time, it is possible to reliably store a uniform amount of filler, and at the same time, the filler is filled at a high density without damaging the ion exchange membrane constituting the wall of the desalination chamber or the like when the filler swells. For the purpose.

Means for solving the problem

  In the present invention, a filler containing an ion exchanger is accommodated in a desalination chamber or a concentration chamber of an electric regeneration type desalination apparatus in a state in which an apparent volume is contracted from its use state, and the volume of the filler in the use environment is stored. In a filling method of a filler that increases the pressure generated between the filler and the chamber wall by mechanically limiting the dimensional change due to expansion by the chamber wall, the weight moisture content in the saturated state of the filler is A filler filling method is provided, wherein a ratio of weight moisture content in a contracted state of the filler is 0.3 to 0.7.

  The filler is a material that is arranged in a desalting chamber or a concentration chamber and exhibits an ion exchange action with a liquid in the chamber. The filler may contain not only an ion exchanger but also a material other than the ion exchanger such as a binder. The filler may be composed of an aggregate of separated materials or a molded body. The aggregate of materials separated from each other refers to, for example, an aggregate of ion-exchange resin particles, and includes not only particles but also fibers and relatively large blocks. The molded product refers to a product in which ion exchange resin particles are integrated by applying heat or pressure or using a binder.

  In the present invention, the state of the filler is changed to fill a room such as a desalting chamber. Hereinafter, in this specification, the state of the filler will be described using the following terms. In this specification, the “saturated state” is a state in which a filler such as an ion exchanger is hydrated to the maximum in an unconstrained state. In addition, the “use state” is a state that is balanced with the environment during use. “Saturated state” and “used state” are almost the same water-containing state.

  However, since the state of use refers to the state when the filler is actually used in a demineralization chamber or the like, it may be restricted by the chamber wall, and in that case, it may be slightly more than the saturated volume. Sometimes it gets smaller. On the other hand, the “shrinked state” refers to a state in which the apparent volume of the filler is actively shrunk by some method, and refers to a state at the time of filling in which the moisture content is reduced unless otherwise specified.

  When the filler is an aggregate, the shape of each material is not particularly limited, but shapes such as a spherical shape, a pellet shape, a fiber shape, a plate shape, and a sheet shape can be employed. These shapes may be used alone or in combination of two or more. There is no restriction | limiting in particular also about a magnitude | size, The thing of various magnitude | sizes is employable.

  When the filler is a molded body, it is preferable because it can contribute not only to prevention of short path formation in the liquid flow direction but also to simplification of the device assembly means. The molded body is preferably one in which ion exchanger particles are bonded and molded into a porous shape using a binder. As the ion exchanger particles, particles similar to those used when the filler is an aggregate can be used, and spherical or pellet ion exchangers are particularly preferable.

  As the ion exchanger, various organic ion exchangers can be used alone or in admixture of two or more. Examples of the organic ion exchanger include an ion exchange resin in which an ion exchange group is introduced into a polymer such as a styrene-divinylbenzene copolymer and an acrylate polymer.

  The method for bringing the filler into a “shrinked state” needs to be selected according to the characteristics of the filler, but when an ion exchange resin is used as the filler, the volume of the ion exchange resin increases as the moisture content increases. Therefore, it is preferable to reduce the moisture content so that the “contracted state” is achieved. Not only when it is dehydrated from the “nearly used” or “saturated” state in advance to the “shrinked state”, but when the ion exchange resin or its molded product is produced, the moisture content is less than the “used state”. This includes cases obtained as products.

  However, in particular, in the case of a general ion exchange resin having a moisture content of 43 to 47% in a saturated state, if the moisture content in the contracted state is set to several percent or less, the difference in volume between the contracted state and the used state (saturated state). In a swelling process from a contracted state to a used state in a specific direction with respect to length, width, thickness or depth even if the contracted filler is correctly placed at a predetermined position in a room such as a desalination chamber An excessive force or displacement may occur in the chamber, which may cause damage to the chamber walls constituting the desalination chamber of the desalination apparatus.

In particular, in the case of an ion exchange membrane constituting the chamber wall of the desalination chamber of the electrodialysis tank constituting the electroregenerative desalination apparatus, the membrane is dragged along with the elongation of the filler, causing wrinkles or membrane breakage. There is a possibility.
In order to prevent such film damage, it is preferable to reduce the displacement of the filler as much as possible. As a result of examination from such a viewpoint, if the ratio of the moisture content in the contracted state of the filler to the moisture content in the saturated state of the filler is 0.3 to 0.7, the swelling of the filler It was found that the ion exchange membrane constituting the desalting chamber wall was not damaged by the displacement of time.

  Furthermore, in order to prevent a short pass and high density filling, it is preferable that the saturated volume of the filler is at least equal to or larger than the volume of the desalting chamber or the like. In this case, when the ratio is close to 1, the volume in the contracted state is larger than the volume of the container when filling the filler, and filling is difficult. Also from such a point, it is necessary to make the said ratio of a filler into 0.3-0.7.

  Heat drying is preferable as a means for reducing the moisture content of the filler. When an ion exchange resin is used as the filler, it is preferable to heat and dry at a temperature of 120 ° C. or lower, particularly 95 ° C. or lower, and more preferably 30 to 60 ° C. in order to prevent deterioration. Furthermore, for the reason of shortening the time or increasing the moisture content change, a method of drying under reduced pressure under a pressure below atmospheric pressure can be used. Similarly, as a method of reducing the moisture content of the filler, there are a method of changing the concentration, composition, type and temperature of the liquid around the filler, and a method of changing the counter ion of the ion exchanger contained in the filler. Available.

  After the filler is stored in a desalting chamber or the like, for example, when immersed in a liquid, the filler gradually expands to a “use state”. In the present invention, since the expansion of the filler is restricted by the chamber wall, the volume of the “use state” is smaller than the “saturation state”. Thereby, pressure is generated between the filler and the chamber wall. When the filler is a molded body, the shape can be a flat plate shape or a cylindrical shape corresponding to the shape of the indoor space. When the shape of the filler is similar to or close to the shape of the indoor space, it is preferable because the pressure generated between the filler and each part of the chamber wall can be made uniform.

  When the filler is a molded body, it is preferable to dispose one continuous filler in a room such as a desalting chamber in order to prevent a short pass, but it may be divided as appropriate. Further, it is not necessary that the whole is a homogeneous filler. For example, a portion including only an anion exchanger as an ion exchanger and a portion including only a cation exchanger as an ion exchanger are arranged in a mosaic pattern. It may be what you have. The filler containing only the anion exchange group and the filler containing only the cation exchange group may be appropriately divided and arranged.

  As an electric regeneration type desalination apparatus to which the filling method of the present invention is applied, an electrodialysis tank having a desalination chamber and a concentration chamber using an ion exchange membrane, a pretreatment apparatus for water to be treated, a concentrated water circulation apparatus, etc. Preferably, the electrodialysis tank has a plurality of cation exchange membranes and anion exchange membranes between an anode chamber having an anode and a cathode chamber having a cathode. In an alternating arrangement, the anode side is partitioned by an anion exchange membrane, the cathode side is partitioned by a cation exchange membrane, the cathode side is partitioned by an anion exchange membrane, and the anode side is cation exchange. A structure in which concentration chambers partitioned by a membrane are alternately formed is preferable.

  It is preferable that the desalting chamber and the concentration chamber in this desalination apparatus are not easily deformed in order to suppress the expansion of the filler and generate pressure, but the ion exchange membrane itself on the chamber wall has sufficient rigidity. In the case where it is difficult to impart strength and strength, for example, when a filler is disposed in the desalting chamber, in order to generate a sufficient pressure from the concentration chamber side, the water permeability is not substantially deformed in the concentration chamber. It is preferred to fill the material.

  Hereinafter, the preparation of the filler used in the filling method and the comparative filling method of the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited by the Examples. Needless to say, it is specified based on the description of the scope of claims.

[Example 1]
Spherical cation exchange resin (Made by Mitsubishi Chemical, trade name Diaion SK1B, weight moisture content 43-50 mass%) and spherical anion exchange resin (Mitsubishi Chemical, trade name Diaion SA10A, average diameter 500 μm) having an average diameter of 500 μm, Weight water content (43 to 47 mass%) was mixed at a volume ratio of 50/50 and dried at 50 ° C. The weight was reduced to less than 3% by weight by drying. To this, a pellet-shaped polyolefin resin (polyolefin plastomer) having a diameter of 2 to 6 mm and a length of 4 to 9 mm was added as a binder so that the binder was 2% with respect to the total amount of the binder and the ion exchange resin. And kneading at 140 ° C. for 40 minutes.

  The kneaded product was put into a rectangular metal mold having an opening surface of 250 mm × 150 mm and pressed at 120 ° C. under the condition of 2.5 MPa to obtain a cuboid porous molded body having a thickness of 7.7 mm. This was allowed to stand for 16 hours in a container kept at a temperature of 25 ° C. and a humidity of 85% or more to adjust the humidity. The thickness at this time was 7.9 mm. The obtained molded body had a weight moisture content of 20.3%, and was used for filling a desalting chamber of an electric regeneration type desalting apparatus. In addition, the weight moisture content in the saturated state of this molded object was 46%.

[Comparative Example 1]
A porous molded body was prepared in the same manner as in Example 1 except that the molded body was not conditioned. The obtained molded body had a weight moisture content of 4%. This was used for filling a desalting chamber of an electric regeneration type desalting apparatus.

[Example 2]
The cation exchange resin and anion exchange resin used in Example 1 were dried at 50 ° C., and the weight water content was reduced to less than 3%. These were weighed by weight ratio as cation exchange resin / anion exchange resin = 54/46, placed in a container with a lid, and water in such an amount that the water content by weight of this ion exchange resin mixture was about 27%. In addition, when well shaken for 1 minute, the water content by weight was approximately 27%. When 100 ml of this mixture was taken in a graduated cylinder, the weight was 76.6 g, and this mixture was used for filling the desalting chamber of the electric regenerative desalting apparatus as in Example 1. In addition, the weight moisture content in the saturated state of the said mixture was 46%.

[Comparative Example 2]
An ion exchange resin mixture was obtained in the same manner as in Example 2 except that the weight moisture content after shaking was 9.0%. When 100 ml of this mixture was taken in a graduated cylinder, the weight was 85.4 g. This mixture was used for filling the desalting chamber of the electric regenerative desalting apparatus in the same manner as in Example 2.

[Comparative Example 3]
About 100 g of water was added to 100 g of the ion exchange resin mixture obtained in the same manner as in Example 2 and mixed well. After removing adhering water from the obtained mixture and measuring with a graduated cylinder, the volume was 249 ml and the weight water content was 37%. This mixture was used for filling the desalting chamber of the electric regenerative desalting apparatus in the same manner as in Example 2.

[Filling of filler and assembly of electrodialysis tank for EDI]
The fillers prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were collected so that the weight of the ion exchange resin was 66 g when the weight moisture content was 0%. However, in Example 1 and Comparative Example 1, the vertical / horizontal ratio of the molded body was set to 1.4 / 1.0.
These fillers were put into a desalting chamber of an electrodialysis tank constituting an electric regenerative desalination apparatus having three desalting chambers and four concentrating chambers, and tightened to a specified size.

  The shape of the desalting chamber is a rectangular parallelepiped, the length in the water flow direction is 140 mm, the width is 100 mm, and the interval between the anion and cation exchange membranes is 8 mm. Each of the concentration chambers was filled with a polypropylene spacer net so that the space between the anion and cation exchange membranes was not substantially changed even when the filler in the desalting chamber expanded. In addition, since the volume of the ion exchange resin mixture of Comparative Example 3 was larger than that of the desalting chamber, the electrodialysis tank could not be substantially assembled. Therefore, the volume of Comparative Example 3 was reduced by 32% to reduce the volume of the desalting chamber. It was assembled in the same manner and filled with the resin mixture, which was referred to as Comparative Example 4.

  When the filler existing in the electrodialysis tank assembled and filled as described above is filled, that is, the weight moisture content in the contracted state, the filler filling volume, the dry dry resin weight of the filler, and the Table 1 summarizes the ratio of the weight moisture content in the contracted state of the filler (weight moisture ratio) to the weight moisture content in the saturated state of the filler.

[Evaluation by EDI desalination]
The desalting chamber of the electrodialysis tank assembled as described above has 21.6 liter / h of pure water having a conductivity of about 10 μS / cm, and 40 liter / h of water having a conductivity of about 100 μS / cm in the concentration chamber. A current of 1.0 A was applied while flowing water having a conductivity of about 100 μS / cm through the anode chamber and the cathode chamber at a rate of 1 liter / h. When it was operated continuously for 40 hours and stabilized, the flow rate of the desalting chamber was set to 43.2 liter / h. Further, the operation was continued for 200 hours, and the pressure loss in the desalting chamber of the electrodialysis tank, the voltage of the electrodialysis tank, and the specific resistance discharged from the desalting chamber were measured. The measurement results are shown in Table 2.

  Except for Comparative Example 3 where assembly of the electrodialysis tank was impossible, when desalting treatment was performed by the EDI method, high purity deionized water could be stably obtained except for Comparative Example 2 and Comparative Example 4. It was. Considering that the voltages in Examples 1 and 2 and Comparative Example 1 were also low, it is considered that no short path occurred in the dilution chamber.

  Therefore, the electrodialysis tank was disassembled and the state of the membrane was observed. As a result, in Example 1, Example 2 and Comparative Example 4, no remarkable damage was observed in the ion exchange membrane constituting the desalination chamber, but in Comparative Example 1 and Comparative Example 2, the filler was swollen. A recumbent that seemed to be pulled by the filler was generated in a direction perpendicular to the flow of the demineralized water. In Comparative Example 1, no visible membrane damage was found, but in the pinhole test using filter paper, bleeding leaks were found in the vicinity of the wrinkles, and in the long-term operation, there was a possibility of reaching the pinhole. There is.

  On the other hand, film tearing was observed in the central portion of Comparative Example 2. The reason why high-purity demineralized water could not be obtained despite the high pressure loss and low voltage is considered not to be caused by a short path but by membrane breakage. Furthermore, although the membrane was not broken, the purity of the desalted water in Comparative Example 4 was low because of the result of the measurement of the pressure loss, from the inlet to the outlet of the desalting chamber or between the filler and the chamber frame, or the ion exchange with the filler. The cause seems to be a gap between the membranes.

Effect of the invention

  By the filling method of the filler of the present invention, it is possible to prevent a short path of the supply water in the desalination chamber of the electric regeneration type desalination apparatus. In addition, a uniform amount of packing material can be reliably stored in multiple desalting chambers or concentrating chambers at the same time, the packing density of the packing material can be increased, and the ion exchange membrane constituting the chamber can be damaged without being damaged. Can be filled in a short time.

Claims (4)

The packing material containing the ion exchanger is stored in the desalination chamber or concentrating chamber of the electric regenerative desalination apparatus in a state in which the apparent volume is contracted compared to the usage state, and the dimensions accompanying the volume expansion of the packing material in the usage environment A shrinkage of the filler with respect to the weight moisture content in saturation of the filler in a filling method of increasing the pressure generated between the filler and the chamber wall by mechanically limiting the change by the chamber wall A filling method for a filler, wherein the ratio of the weight moisture content in the state is 0.3 to 0.7.   2. A filling material filling method according to claim 1, wherein the filling material comprises an aggregate of materials separated from each other.   The method for filling a filler according to claim 1, wherein the filler comprises a molded body.   The filling material filling method according to any one of claims 1 to 3, wherein the filling material is contracted by drying.