JP3473705B2 - Preparation method of mixed slurry of precoat material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a mixed slurry of a precoat material for filtration, and more particularly to a method for preparing a mixed slurry containing ion exchange fibers and an ion powder resin as a precoat material.

[0002]

2. Description of the Related Art Strongly acidic powder ion exchange resin (hereinafter referred to as cation powder resin) and strong basic powder are used for removing suspended and ionic impurities contained in water conventionally used in nuclear power plants. Ion exchange resin (hereinafter, anion powder resin
Precoat type filter method using a filter aid material by mixing) that is used. When precoating with a filter aid at a constant low concentration, a good precoat layer can be formed without using a polymer or an electrolyte.

In a filter for precoating a cation / anion powder resin, suspended impurities in water are removed by the precoat layer while passing through a layer near the surface layer of the precoat layer in the initial stage of water collection (volume. When the water collection progresses, the flow path is clogged with the removed impurities, resulting in filtration on the surface of the precoat layer (surface filtration), and the differential pressure increases. The precoat layer is consolidated by this differential pressure, and the increase in differential pressure becomes larger and the end point is reached.

[0004]

[Problems that the Invention is to Solve The cationic powder tree <br/> fat, the precoat type filtration method using an anion powder resin as filtration aids, suspension concentrate, improvement of water quality can often remove ions like impurities However, used filter aid is generated as waste. The used filter aid must be treated with asphalt or the like and packed in drums to be stored in the power plant, but in nuclear power plants, it is necessary to reduce the amount of waste generated as much as possible. An object of the present invention is to provide a method for preparing a mixed slurry of precoat materials, which enables accurate and mechanical precoat filtration with a long filtration life for reducing the amount of waste generated.

[0005]

In order to solve the above problems, in the present invention, a water content of 35 to 5 is used as a precoat material.
Using 0% cation-exchange fiber , cation powder resin, and anion powder resin, each hopper was filled, and the rotor provided at the bottom of each hopper was rotated to rotate the blades of the rotor. The precoat material filled between the blade and the blade is discharged to the slurry mixing tank,
A method for preparing a mixed slurry of a precoat material for filtration, characterized in that a mixed slurry of the precoat material is obtained.

In the above adjusting method, the cation-exchange fiber of the precoat material and the cation powder resin may be mixed and filled in one hopper, in which case the water content of the cation-exchange fiber is 35 to 50%. Then, the water content of the cation powder resin is preferably 40 to 45%.

[0007]

[Function] When short fibers are mixed with the cation / anion powder resin precoat material, a precoat layer having an appropriate space is formed together with the powder resin, and when water is sampled, volumetric filtration is performed inside the precoat layer. Even if the differential pressure rises, the fibers are entangled, so that the fibers are strong against compression, and the precoat layer is less likely to be consolidated, and the differential pressure rise is slow, and the life is long.

[0008] Examples of such fibers, having a cation exchange capacity, in the base material styrene, cation exchange fiber containing the reinforcing core of polyethylene. The shape is 40 in diameter
A columnar shape having a length of ˜50 μm and a length of 200 to 500 μm,
Its water content is 60-70%. This fiber is cation powder resin / anion powder resin / cation exchange fiber = 5
When used in a ratio of 5/15/30 to 35/15/50, the filtration life can be extended by 1.5 to 3 times as compared with the case of using only powder.

When the cation exchange fiber is filled in the hopper, the cation exchange fibers are entangled with each other and the water content is as high as 60 to 70% (the cation powder resin is 40 to 40%).
45%, 55-60% for anion powder resin), the cation exchange fiber causes a crosslinking phenomenon inside the hopper, and even if the scraping blade is rotated, it cannot be discharged from the discharge port. Also, in the rotor part, the cation-exchange fibers between the blades and the blades and the rotor cannot be discharged from the lower part of the rotor due to the entanglement of the cation-exchange fibers or due to the large amount of water, or Quantitative discharge was left behind at the root of the blade and rotor.

Therefore, in order to quantitatively discharge the air, air was blown between the blades in the rotor chamber to force the air to be discharged, but the amount decreased, but the cation-exchange fiber remained.
Next , a test to dry and discharge the cation exchange fiber
It was Tsu line. In this test, the cation exchange fibers were placed in a dryer and dried at 50 ° C for several hours. Then, several cases making what moisture is reduced in drying, was subjected to a discharge test for each, than the following 52% moisture remaining cation exchange fibers during blade and the blade was Tsu or such was observed.

The exchange capacity of this dried cation exchange fiber was measured and found to be 3 to 3.5 meq / g-dr.
There was no change in y . However, when the shape of the dried cation exchange fiber was observed, when the water content was 32% or less, the slenderness ratio became small, and the shape change was observed. When the hopper 1 is filled with the precoat material, the water content of the precoat material evaporates and rises to the upper part of the hopper, but it comes into contact with the wall to form water droplets and adhere. When these water droplets collect, they may flow down the hopper wall and flow down to the lower part of the hopper, increasing the water content of the precoat material at the lower part of the hopper and impairing the quantitative discharge property.

Therefore, from the viewpoint of safety, if the water content of the cation exchange fiber is 35 to 50%, the cation exchange fiber is well discharged from the hopper, the quantitative discharge property from the rotor chamber is also good, and the physical properties are not changed. Further, if the cation exchange fiber and the cation powder resin can be packed in one hopper, the hopper equipment can be saved. About 2/1 with cation exchange fiber dried to 48% using cation powder resin with water content of 40-45%
When the mixture was mixed at a ratio of 1, and an emission test was performed, the rest was not seen. Thus, when 35% to 50% moisture by drying the cation exchange fiber, a hopper, a resin supply apparatus provided with a rotor chamber, a precisely pre-coated material with automatic remote can be fed to a slurry mixing tank, Moreover, it does not impair the filtration performance.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings, but the present invention is not limited thereto. Example 1 A schematic view of a precoat type filtration device using the present invention is shown in FIG. 1, and a partial enlarged view of a lower portion of a hopper for filling a precoat material is shown in FIG. A precoat material composed of a cation exchange fiber having a water content of 35 to 50%, a cation powder resin and an anion powder resin is separately stored in the hopper 1 shown in FIG. As shown in a partially enlarged view of FIG. 2, these hoppers 1 have a discharge port 4 in a bottom plate 3 and are filled inside the hopper by rotating a scraping blade 2 at the bottom of the hopper. The precoat material is discharged downward from the discharge port 4.

A rotor chamber 5 is provided below the hopper 1, and several blades 7 are provided in the rotor 6 so that the precoat material is stored between the blades. A discharge port 8 is provided at the bottom of the rotor chamber, and when the rotor rotates, the precoat material accumulated between the blades is discharged from the connecting pipe 9 to the slurry mixing tank 11 through the discharge port 8. In the same manner, different precoat materials are supplied from the different hoppers 1, and they are respectively charged into the slurry mixing tank 11,
The mixture is agitated by the agitator 12 to prepare a mixed slurry having an 8% concentration.

The adjusted slurry is sucked out by an eductor to have a concentration of 4%, and further, 0.04% by circulating water circulating between the filter and the precoat tank 16.
It is diluted to% concentration, fed to the filter and pre-coated on the filter element 15. And the circulating water is pipe 2
3 is returned to the precoat tank 16 from where it is circulated in the pipe 21 together with the mixed slurry from the pipe 19 from the pipe 22 to the filter 14 by the pump 20.

Here, the rotation of the rotor is performed by the electric motor 10, and the water content of the precoat material is adjusted by controlling the rotation of the electric motor 10. Therefore, the input amount of the precoat material can be properly controlled. it can. With the above method,
A filtration test was carried out using cation exchange fibers having a water content of 45% and those having a water content of 65% for comparison. The results are shown in Table 1.

[0017]

[Table 1] Thus, the filtration performance did not change depending on the water content.

[0018]

According to the present invention, the precoat material can be accurately and mechanically supplied to the slurry mixing tank through the rotor at the lower part of the hopper, and the mixed slurry of a constant quality can be adjusted.

[Brief description of drawings]

FIG. 1 is a schematic view of a precoat type filtration device using the present invention.

[Fig. 2] Partially enlarged view of hopper and rotor chamber

[Explanation of symbols]

1: hopper, 2: hopper scraping blade, 3: hopper bottom plate, 4: hopper discharge port, 5: rotor chamber,
6: rotor, 7: rotor blade, 8: rotor outlet, 9: connecting pipe, 10: electric motor, 11: slurry mixing tank, 12: agitator, 13: eductor, 14: filter, 15: filter element, 16 : Precoat tank,
17, 19, 21, 22, 23: Piping, 18: Pure water, 2
0: Pump, 24: Treated water, 25: Treated water

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B01D 37/02

Claims (2)

(57) [Claims] 1. A water content of 35 to 50 as a precoat material.
% Cation exchange fiber , strongly acidic powder ion exchange resin, and strongly basic powder ion exchange resin are used, filled in separate hoppers, and the rotor provided at the bottom of each hopper is rotated. A method for adjusting a mixed slurry of a precoat material for filtration, comprising: discharging a precoat material filled between blades of a rotor into a slurry mixing tank to obtain a mixed slurry of the precoat material. 2. A cation exchange fiber of the precoat material,
It is mixed with a strongly acidic powder ion exchange resin and filled in one hopper, and the water content of the cation exchange fiber is 35-35.
50% and the water content of the strongly acidic powder ion exchange resin is 40%.
The method for adjusting the mixed slurry of the precoat material for filtration according to claim 1, wherein the content is set to 45%.