JPH03284311A - Sintered wire net filter medium and filter element using the same - Google Patents

Abstract

PURPOSE:To form a sintered wire net with the clogging reduced by placing two twilled wire nets with the longitudinal and lateral opening being extremely fine on each other so that the angle between the warp and weft is controlled to 90 deg. and sintering the laminate. CONSTITUTION:A protective wire net 1, a sintered wire net filter medium 2, a protective wire net 3, a reinforcing wire net 4 and a reinforcing wire net 5 are successively arranged from a filtrate contact surface to constitute a filter element. The reinforcing wire nets 4 and 5 are used to reinforce the filter medi um against the filtration pressure exerted on the filter medium 2 surface. The wire nets 4 and 5 are a twilled wire net of a stainless steel wire and having about 12 longitudinal mesh and about 64 lateral mesh, and the nets are placed on each other so that the angle between the warp and weft is controlled to 90 deg., pressed on the inner side face of the protective wire net 3 and sintered to weld the respective contacts. The effect in separating a current to the rein forcing wire nets 4 and 5 is enhanced by the protective wire net 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a filter, particularly an extremely small one in the micron range, used in a filter in the clarification process of a spent nuclear fuel reprocessing plant received from a nuclear power plant. The present invention relates to a wire mesh sintered filter material for filtering out undissolved solid particles, and a filter element using this wire mesh sintered filter material.

[Prior art] In the solution clarification process at a reprocessing plant for spent nuclear fuel received from nuclear power plants, etc., the particle size contained in the dissolved solution/fL (nitric acid solution) of spent nuclear fuel is 5 to 0. It is required to remove 95% or more of extremely fine solid particles of micron size.

Conventionally, a pulse filter using a sintered metal powder filter element made of sintered stainless steel metal powder has been used as a filter that satisfies these conditions.

[Problem to be solved by the invention] However, although the metal powder sintered filter medium for filtering out extremely small solid particles on the micron scale as described above has extremely excellent collection efficiency, the layer of the filter medium The filtration holes are thick, the shape of the filtration holes is complicated, and the liquid passage is bent, resulting in high filtration resistance, and the filtration speed is greatly reduced due to clogging with particulates. In addition, the clogging is severe, and further cleaning (
It is also difficult to obtain a sufficient effect in clogging recovery by backwashing. Therefore, filter elements using such conventional filter media have the disadvantage that they must be replaced extremely frequently.

However, when handling radioactive materials such as nuclear fuel, in order to prevent contamination from spreading outside, filters must be cleaned before replacing them, and the transport cask and work area may be damaged by dripping liquid during replacement. It is necessary to drain the liquid sufficiently and dry it naturally to avoid contamination, which results in a decrease in the operating rate.

Another problem is that because filter elements are frequently replaced, the number of filter elements becomes high-level radioactive waste.

The present invention has been developed in view of the above-mentioned problems of the conventional technology, and its objectives are to have low filtration resistance, a low degree of clogging, and to be easier to clean even in the event of clogging. The present invention aims to provide a wire mesh sintered filter material that can remove clogging and filter out extremely fine solid particles on the micron scale, and a filter element using this wire mesh sintered filter material.

[Means for Solving the Problems J] In order to achieve the above object, the wire mesh sintered filter medium of the present invention consists of two pieces of twilled woven wire mesh with extremely fine openings in either the vertical or horizontal direction, each vertically or horizontally. The wires and horizontal wires are overlapped so that the intersection angle is 90 degrees, and then pressurized and sintered to integrate them.

Furthermore, the filter element of the present invention is constructed by sequentially disposing a protective wire mesh, a wire mesh sintered filter medium of the present invention, a protective wire mesh, and a reinforcing wire mesh from the filtrate contact surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

In this example, a twill woven wire mesh made of stainless steel wire with a length of 325 meshes (wire diameter 0,035 i+m) and a width of 2400 meshes (wire diameter 0.025m1) was used as the basic wire mesh, and two pieces of this basic wire mesh were used. are overlapped so that the respective vertical lines and horizontal lines intersect with each other at a 90 degree angle, and then pressurized and sintered to bond the vertical lines and horizontal lines at their intersections where they touch each other. The wire mesh sintered filter medium of the present invention is constructed as described above.

In this example, a twill woven wire mesh with 325 meshes in length and 2400 meshes in width was used as the basic wire mesh.
Depending on the case, the number of meshes may be even smaller by 270 meshes in height and 20 meshes in width.
00 meshes, or 500 vertical meshes with many words,
Twill woven wire mesh with a width of 3,600 mm can also be used. If the mesh is too small, the particle collection efficiency will decrease, and if the mesh is too large, it will be difficult to manufacture the wire mesh and there will be problems with its strength. 50o metsunyu, tl! 12000~3
It is preferable to use a 600 mesh twill wire mesh.

FIG. 1 is a perspective cross-sectional view of the essential parts for explaining the configuration of a filter element using the wire mesh sintered filter medium of the present invention.
From the filtrate contact surface, the protective wire mesh (1), the wire mesh sintered filter medium of the present invention (2), the protective wire mesh (3), the reinforced wire mesh (4), and the reinforced wire mesh (
5) are sequentially arranged to constitute the filter element of the present invention.

The protective wire mesh (1) and (3) are both wire mesh sintered filter media (
2) with 300 mesh (wire diameter 0.1m)
The wire mesh sintered filter medium (2) is sandwiched between the stainless steel wire plain weave wire mesh (m), and both sides thereof are pressed and sintered. In addition,
The protective wire mesh (3) not only protects the wire mesh sintered filter medium (2) but also has the effect of improving the effect of dividing the flow to the reinforcing wire meshes (/I) and (5).

The reinforcing wire meshes (4) and (5) are both used to reinforce the filter material against the filtration pressure applied to the surface of the filter material (2), and both of the reinforcing wire meshes (4) and (5) are vertical! 2 mesh (wire diameter 0.6
mm), a flat tatami-woven wire mesh made of stainless steel wire with a width of 64 mesh (wire diameter 0.4 mm), stacked inside the protective wire mesh (3) so that the intersection angle of each vertical line and horizontal line is 90 degrees. Pressure is applied to the sides, sintering is performed, and each contact area is welded.

Next, changes in particulate collection efficiency and filtration speed of the pulse filter using the wire mesh sintered filter element of the present invention shown in the above example were measured, and compared with the pulse filter using the conventional metal powder sintered filter element. Contrasted.

Table 1 shows the measurement results of particulate collection efficiency.

Note: Collection efficiency is expressed in number percent.

(a) d≦5μm (b)
5 μs < d ≦ 10 μm (c) 10 μm < d [d; Particle size] Figure 2 shows a pulse filter using the wire mesh sintered filter element of the present invention and a pulse filter using the conventional metal powder sintered filter element. This is a curve comparing the filtration speed with a filter, and the measurement conditions are as follows.

Operating conditions Vacuum level: -0.9m^q Backwash pressure
・0.9 Kg/cI11' Backwash time; 5
．． 0sec Filtration area: 1350 cm" Liquid supply conditions Residue concentration: 0.6 g/L Residue particle size: 5 to 10 μm Liquid temperature: Room temperature (approximately 25°C) [Effects] As described above, the wire mesh sintered filter of the present invention The particulate collection efficiency of a pulse filter using an element is
Not only is the pulse filter using the conventional metal powder sintered filter element superior to that of the conventional metal powder sintered filter element, but the pulse filter using the wire mesh sintered filter element of the present invention is also superior to the conventional metal powder sintered filter element. Compared to a pulse filter using an element, the filtration rate of particulates and its change over time (rate of decline) are extremely superior.

Furthermore, since the wire mesh sintered filter medium of the present invention is made by sintering two wire meshes, it has lower filtration resistance and less clogging than conventional metal powder sintered filter media. Furthermore, the wire mesh sintered material of the present invention mainly collects fine particles through surface filtration, and even when clogged, it is easy to recover from the clog by washing (backwashing). Therefore, the backwash performance is extremely good, and the amount of liquid processed (life) is about 15 times that of a filter element using a conventional metal powder sintered filter element.

Therefore, if used in a pulse filter that filters out micron-sized undissolved solid particles in a solution in the clarification process of spent nuclear fuel reprocessing plants such as nuclear power plants,
Since the downtime during element replacement is shortened, the operating rate is improved, and since the frequency of element replacement is low, the amount of radioactive waste generated can be significantly reduced.

[Brief explanation of drawings]

Fig. 1 is a perspective cross-sectional view of a main part illustrating the configuration of a filter element using the sintered wire mesh filter medium of the present invention, and Fig. 2 shows a pulse filter using the sintered wire mesh filter element of the present invention and a conventional metal powder filter. 1 is a curve comparing filtration speed with a pulse filter using a sintered filter element. ], 3. Protective wire mesh, 2. Sintered wire mesh filter material 4.5.
- Reinforced wire mesh A...Filtration speed curve of a pulse filter using the sintered wire mesh material filter element of the present invention B...Filtration speed curve of a pulse filter using a conventional metal powder sintered filter material filter element

Claims (1)

[Claims] 1. Two pieces of twilled tatami wire mesh with extremely fine openings in either the vertical or horizontal direction are superimposed so that the vertical and horizontal lines intersect with each other at a 90 degree angle. A wire mesh sintered filter material characterized by being integrated after being pressurized and sintered. 2. Twill tatami wire mesh, length 270-500 mesh, width 20
The wire mesh sintered filter medium according to claim 1, which is a twilled wire mesh of 00 to 3600 mesh. 3. A filter element in which a protective wire mesh, a wire mesh sintered filter medium, a protective wire mesh, and a reinforcing wire mesh are sequentially arranged from the filtrate contact surface, wherein the wire mesh sintered filter medium is constituted by the wire mesh sintered filter medium according to claim 1 or 2. A filter element characterized by: