JP4502084B2 - Mixed bed type ion exchange resin tower and method for forming the mixed bed - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mixed bed ion exchange resin tower and a method for forming the mixed bed , and more particularly, a mixed bed ion exchange resin capable of efficiently separating a cation exchange resin and an anion exchange resin during regeneration separation of the ion exchange resin. The present invention relates to a method for forming a tower and its mixed bed .
[0002]
[Prior art]
Mixed-bed ion exchange resin towers are used for the purpose of removing or separating impurities in water or solvents in, for example, pure water equipment, condensate desalination equipment at power plants, soft water equipment, food-chemical processes, etc. Is done. Conventionally, in such a mixed bed type ion exchange resin tower, a cation exchange resin or an anion exchange resin having a wide Gaussian distribution (normal distribution) as a resin particle size has been used. in order to improve the improvement and particulate removal capability, it has become narrow uniform particle size resins having distribution width is used. The ion exchange resin used in this way must be regenerated with a drug after being used for a certain period.
[0003]
Conventionally, for the regeneration of the mixed bed, after interrupting normal operation, first aeration with air or other gas is performed to loosen the resin and make it easy to separate the resin, and then the particle size of the resin by back washing with water The cation exchange resin is moved to the lower part and the anion exchange resin is moved to the upper part by utilizing the difference in the sedimentation rate due to the specific gravity to form the cation exchange resin layer and the anion exchange resin layer, which are separated and regenerated.
[0004]
[Problems to be solved by the invention]
However, when trying to separate a mixed bed layer composed of a cation exchange resin and an anion exchange resin having a uniform particle size by backwashing with water using a difference in sedimentation speed, the conventional Gaussian distribution is changed due to the uniformity of the particle size. Compared with the resin (hereinafter referred to as the conventional resin), the cation and anion layers flow violently, and the resin of the mating layer is drawn into each layer, and the drawn resin together with the mating resin is a resin layer. The phenomenon of flowing greatly occurs. The resin once drawn in this way is not easily separated again by this flow, and it takes a long time to return to the original layer from the resin interface again.
[0005]
In addition, when a new ion exchange resin is used, the cation exchange resin and the anion exchange resin tend to be entangled at the beginning of use, and therefore the above-described pulling phenomenon tends to occur remarkably.
[0006]
Furthermore, even a slight fluctuation in the flow rate of the backwash water is greatly affected, and this flow is greatly disturbed, causing the separation layer to be broken and the resin to be drawn deeply. For this reason, a careful operation and a longer separation time than before are required to handle the uniform particle size resin.
[0007]
In addition, a method of improving the separability by adding a resin having an intermediate specific gravity between the cation exchange resin and the anion exchange resin and having no ion exchange ability is also performed. However, since a resin having an intermediate specific gravity and no ion exchange ability is added, the uniformity of the packed bed is disturbed, and the apparatus performance such as ion exchange ability and fine particle removal ability is deteriorated.
[0008]
In view of such circumstances, the present invention provides a mixed bed type ion exchange resin tower comprising a cation exchange resin and / or an anion exchange resin having a uniform particle size distribution . It is an object to provide a forming method .
[0009]
[Means for Solving the Problems]
A first aspect of the present invention that solves the above-described problems includes a cation exchange resin having a uniform particle size distribution in which a particle size distribution is ± 50 μm with respect to an average particle size of 650 μm, and a uniform particle size distribution of the cation exchange resin. The mixed-bed ion exchange resin tower is characterized by comprising an anion exchange resin having a particle size distribution wider than the particle size distribution.
[0010]
According to a second aspect of the present invention, in the mixed-bed ion exchange resin tower according to the first aspect, a particle size distribution wider than the particle size distribution of the uniform particle size distribution is a Gaussian distribution. It is in the mixed bed type ion exchange resin tower.
The third aspect of the present invention includes (a) a cation exchange resin having a uniform particle size distribution with a particle size distribution of ± 50 μm with respect to an average particle size of 650 μm, and (b) a particle size with respect to an average particle size of 550 μm. An anion exchange resin having a uniform particle size distribution with a distribution of ± 50 μm, and (c) particles having an average particle size smaller than the average particle size of the cation exchange resin and wider than the particle size distribution of the uniform particle size distribution At least one of a cation exchange resin having a size distribution and an anion exchange resin having an average particle size larger than the average particle size of the anion exchange resin and a wider particle size distribution than the uniform particle size distribution The mixed bed type ion exchange resin tower is characterized in that a mixed bed of the mixed bed type ion exchange resin tower is formed by mixing one of them so that the amount (c) is 2 to 5% of the total amount. The method of forming a mixed bed.
[0011]
Here, the conventional resin having a Gaussian distribution is a resin having a wide particle size distribution of the resin, while the uniform particle size resin is a resin having a narrower particle size distribution than the conventional resin. As an example of a conventional resin, for example, an ion exchange resin having a particle size distribution range of 200 to 1180 μm and a particle size having a Gaussian distribution can be given. Examples of the uniform particle size resin include exchange resins whose particle size distribution is controlled to ± 100 μm, preferably ± 50 μm with respect to the average particle size.
[0012]
In the present invention, the ratio of adding the conventional resin of small particle size of cation exchange resin or the conventional resin of large particle size of anion exchange resin to the mixed bed of uniform particle size resin is preferably 10% or less, preferably Is 2-5%. If a conventional resin is added in an amount of 10% or more based on the total amount, the effect of using a resin having a uniform particle size is undesirably reduced.
[0013]
Moreover, what is necessary is just to make it the mixing ratio of the cation exchange resin and anion exchange resin which form the conventional mixed bed, when mixing and using a uniform particle size resin and conventional resin.
[0014]
When water backwashing is performed on a mixed bed composed of a cation exchange resin and an anion exchange resin having a uniform particle size resin, all the resin flows uniformly in each resin layer. Moreover, the flow range is large, and it flows from the lower part of each resin layer to the upper part. On the other hand, according to the backwash time, the conventional resin moves in the lower part when the particle size is larger and moves toward the upper part when the particle size is smaller, and fluidly aligns in the resin fluidized bed. Therefore, the flow of the resin is limited to the flow in the local area, and the flow over all the resins such as the resin having a uniform particle diameter is hardly generated.
[0015]
In the present invention, a small particle size conventional resin of cation exchange resin or a large particle size conventional resin of anion exchange resin is added to cation exchange resin and anion exchange resin of uniform particle size resin, or uniform particle size resin and conventional resin Can be used to form a locally small layer of fluid at the interface, thus preventing the resin having a uniform particle diameter from being pulled in and improving the separability.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on examples.
[0017]
(Examples 1-4, comparative example)
An ion exchange resin layer was formed by mixing and filling the following resins in a column having an inner diameter of 50 mm and a height of 2000 mm.
[0018]
Example 1:
Cation exchange resin 1.5 liter uniform particle size resin (95%)
: Gel-type cation exchange resin Dowex 650C (manufactured by Dow Chemical Company)
: Particle size: 650 μm ± 50 μm
Conventional resin (5%)
: Gel-type cation exchange resin Dowex 50W-X8 (manufactured by Dow Chemical Company)
: Particle size: 300 μm to 500 μm (particle size adjusted product)
Anion exchange resin 0.7 liter uniform particle size resin (100%)
: Gel type anion exchange resin Dowex 550A (manufactured by Dow Chemical Company)
: Particle size: 550 μm ± 50 μm
[0019]
Example 2:
Cation exchange resin 1.5 liter uniform particle size resin (100%)
: Gel type cation exchange resin Dowex 650C
: Particle size: 650 μm ± 50 μm
Anion exchange resin 0.7 liter uniform particle size resin (95%)
: Gel type anion exchange resin Dowex 550A
: Particle size: 550 μm ± 50 μm
Conventional resin (5%)
: Gel type anion exchange resin Dowex SBR (manufactured by Dow Chemical Company)
: Particle size: 650 μm to 1000 μm (particle size adjusted product)
[0020]
Example 3:
Cation exchange resin 1.5 liter uniform particle size resin (100%)
: Gel type cation exchange resin Dowex 650C
: Particle size: 650 μm ± 50 μm
Anion exchange resin 0.7 liter conventional resin (100%)
: Gel type anion exchange resin Dowex SBR
: Particle size: 650 μm to 1000 μm (particle size adjusted product)
[0021]
Reference example :
Cation exchange resin 1.5 liter Conventional resin (100%)
: Gel-type cation exchange resin Dowex 50W-X8
: Particle size: 350 μm to 1180 μm
Anion exchange resin 0.7 liters Uniform particle size resin (100%)
: Gel type anion exchange resin Dowex 550A
: Particle size: 550 μm ± 50 μm
[0022]
Comparative example:
For comparison, an ion exchange resin layer made only of a uniform particle size resin was formed as follows.
[0023]
Cation exchange resin 1.5 liter uniform particle size resin (100%)
: Gel type cation exchange resin Dowex 650C
: Particle size: 650 μm ± 50 μm
Anion exchange resin 0.7 liter uniform particle size resin (100%)
: Gel type anion exchange resin Dowex 550A
: Particle size: 550 μm ± 50 μm
[0024]
Ammonia water equivalent to 50% of the exchange capacity of the cation exchange resin was passed through each of the ion exchange resin layers described above, and then the resin was separated by performing air aeration for 5 minutes and water backwash for 30 minutes.
[0025]
A 2.5 cm width (about 100 ml) was collected on both sides of the cation-anion interface center of the resin after separation. Next, the collected anion exchange resin layer and cation exchange resin layer were immersed in a 25% NaOH solution, and the volumes of the cation exchange resin and anion exchange resin mixed in another resin layer were measured.
[0026]
The results are shown in Table 1.
[0027]
[Table 1]
On the cation exchange resin side On the anion exchange resin side
Mixed anions Mixed cations
Exchange resin ratio (%) Exchange resin ratio (%)
Example 1 0.1 0.01
Example 2 0.5 0.01
Example 3 0.7 0.01
Reference example 0.1 0.03
Comparative Example 3 0.2
[0028]
【The invention's effect】
As described above, according to the present invention, it is possible to adopt a uniform particle size resin without major modification to a conventional device intended for resin, and in a device based on the premise that a uniform particle size resin is used from the beginning. The apparatus can be simplified without incorporating a simple mechanism. In addition, even if a resin having a uniform particle size is used, it is possible to prevent the resin from being drawn in, and the quality of the treated water can be improved. Furthermore, the time required for resin separation is shortened, and the influence of contamination, resin degradation, and the like can be reduced.

Claims (3)

A cation exchange resin having a uniform particle size distribution with a particle size distribution of ± 50 μm with respect to an average particle size of 650 μm, and an anion exchange having a wider particle size distribution than the uniform particle size distribution of the cation exchange resin A mixed bed ion exchange resin tower characterized by comprising a resin.   2. The mixed bed ion exchange resin tower according to claim 1, wherein a particle size distribution wider than the uniform particle size distribution is a Gaussian distribution. 3. (A) a cation exchange resin having a uniform particle size distribution with a particle size distribution of ± 50 μm with respect to an average particle size of 650 μm;
(B) an anion exchange resin having a uniform particle size distribution with a particle size distribution of ± 50 μm with respect to an average particle size of 550 μm;
(C) a cation exchange resin having an average particle size smaller than the average particle size of the cation exchange resin and a particle size distribution wider than the uniform particle size distribution, and the average particle size of the anion exchange resin An anion exchange resin having a larger average particle size and a wider particle size distribution than the uniform particle size distribution,
The mixed bed of the mixed bed type ion exchange resin tower is formed by mixing so that (c) is 2 to 5% with respect to the total amount of the mixed bed type ion exchange resin tower. Forming method.