JP2003093821A - Fire retardant filter and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance fire retardant filter for collecting dust by passing air through pleated glass filter paper from the internal cavity part of a cylindrical filter to allow the air to flow in the outer peripheral direction of the cylindrical filter. SOLUTION: The fire retardant filter comprises the cylindrical filter 30, which is formed by holding both surfaces of glass filter paper 20 having a high performance air filter (HEPA) between reticulated layers comprising an ethylene/tetrafluoroethylene copolymer 10 being fluoroplastics to press and reinforce the glass filter paper and folding the reinforced glass filter paper into a pleated shape to form the same into a cylindrical shape, and a lid 33 having a hole 34 provided to the center thereof and a lid 32 provided with no hole, both of which are made of SUS 304 and respectively bonded to both ends of the cylindrical filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant filter suitable for use in the treatment of radioactive gas waste in a nuclear facility such as a nuclear power plant and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, radioactive gas wastes include dusty ones attached to dusts and gaseous ones. Dust-like radioactive gas wastes can be collected in pre-filters, medium-performance air filters and high-efficiency air filters.
culate air filter; HEPA filter).

A high-performance air filter has a removal efficiency of 99.97% or more with respect to particles of 0.3 μm (micron), and the filter is folded into an accordion shape in order to increase the filtration area. By sandwiching a corrugated separator (made of aluminum or the like), the filtration area of the flat filter is increased by about 60 times the apparent cross section.
In addition, products that withstand high temperatures and high humidity have also been commercialized (reference: Nikkan Kogyo Shimbun, book title: Basics of radiation protection, author: Tadashi Tsujimoto / Tomoko Kusama).

Further, in order to make the filtration area larger than the apparent cross section, Japanese Patent No. 2665691 discloses a cylindrical filter. In this patented invention, the filter is folded into an accordion shape in order to increase the filtration area (this is referred to as a pleated shape in this specification), the filter material folded into the pleated shape is rolled into a cylindrical shape, and the inner cavity side of the cylinder is closed. From the outer circumference of the cylinder to the air (or a method of flowing the air in the opposite direction is also generally used).
Further, the inner wall shape is not a normal cylindrical shape, but a frustoconical shape in which the opening area of the air inlet is increased and the opening area is decreased toward the air outlet. Further, a wire mesh is used as a filter medium reinforcing material of the disclosed filter. On the other hand, the characteristics of filter paper are not described. Although it seems that the purpose is different, a filter product in which a pleated filter paper is circular is found in the general market.

A flame-retardant filter having a high performance is 0.3
A removal efficiency of 99.97% or more is required for μm (micron) particles. The filter paper that guarantees this high performance is
Fine and soft. In order to finish this filter paper into pleats and process it into a cylindrical shape, it was necessary to reinforce the filter paper, and the reinforcing material had to be reticulated. When a wire net is used, the filter paper may be damaged by the wire net.

The outer shape of the filter is changed from a flat shape to a cylindrical shape in order to satisfy the demand for a large capacity in a small area, but there is a problem in that the sharp edges of the pleated filter medium come into contact with each other. Further, it is difficult to maintain the interval between the pleats, and the filter paper itself is soft, so there is a risk that it will collapse and be buried. It is necessary to reinforce the filter paper from the front and back,
For that purpose, the selection of a material having a specific elasticity and the setting of the combination of the wire diameter and the particles when reinforcing in a net-like manner were problems.

[0007]

In order to solve the above-mentioned problems of the prior art, it is necessary to finish fine and soft filter paper into pleats and then process it into a circle. Therefore, a reinforcing material is necessary. However, depending on the reinforcing material, the filter paper may be destroyed, and a reinforcing material that does not destroy the filter paper and a material that also has flame retardancy are required. As a reinforcing material, there is a certain elasticity,
When it is reinforced in a mesh shape, it is a material that is easy to combine the wire diameter and particles, and it is also easy to process into pleats,
It must be flame-retardant so that it does not lose its shape,
In this way, there was a problem in selecting materials.

Further, the filter paper includes MIL-STD MIL.
-It is a high-performance air purifying filter paper specified in F-51079C and requires flame retardancy. Under such various requirements and restrictions, the present invention provides a flame-retardant filter having flame retardancy, strength, and elasticity, which is suitable for treating radioactive gas waste, and a method for producing the same. It is an issue.

[0009]

As a filter for solving the above-mentioned problems, the present invention is designed to pass a gas through an inner cavity of a cylindrical filter composed of pleated glass filter paper through the filter paper and to flow gas in an outer peripheral direction. In a filter for removing dust, a glass filter paper showing the property that the capture rate of 0.3 μm dioctyl phthalate particles is 99.9% or more under the condition that the surface wind velocity is 5.33 cm / sec is formed by reticulated ethylene of a fluorine resin. / Tetrafluoroethylene (hereinafter referred to as ETFE)
A cylindrical filter which is sandwiched with a copolymer and press-reinforced from the front and back is folded into a pleat shape to form a cylindrical filter, and a lid made of metal, preferably SUS304, having a hole at the center and a lid having no hole at the center. A flame-retardant filter bonded to the end of the cylindrical filter is provided.

The filter of the present invention employs a glass fiber filter paper generally called HEPA which meets the MIL standard, and is flame-retardant, and moreover, at a high temperature for treating radioactive gas wastes emitted from nuclear facilities. It has high performance and is safe even when used under humid conditions.

Further, the filter according to the present invention is ETFE.
Since the cylindrical filter is constructed by sandwiching both sides of the glass filter paper with a reinforcing material made of a mesh of a copolymer, the reinforcing material has elasticity, and it is reinforced by pressing from both sides of the glass filter paper. However, it does not break the glass filter paper. Further, the glass filter paper reinforced with the reticulated ETFE copolymer is easily processed into pleats and does not lose its shape.

The reticulated ETFE copolymer used in the flame-retardant filter of the present invention has a wire diameter of 0.12 to 0.25.
When a combination of mm and particle size 20 to 60 mesh is used, the soft glass filter paper can be reinforced in optimal condition from both sides.

The present invention also provides a method of manufacturing a filter for solving the above problems, in which a filter paper for capturing dust and a filter formed by covering the front and back of the filter paper with a reinforcing material to form a pleated shape are used. A step of preparing to supply a filter paper and a reticulated ETFE copolymer; a step of sandwiching the glass filter paper from the front and back using the reticulated ETFE copolymer to press-reinforce it through a slitter machine;
The step of folding the pressure-reinforced material into pleats and heating the tip of the filter with an acute angle to perform reciprocal folding, and cutting into the number of folds according to the size of the circle of the filter to cut the cut surface of the filter into two parts Provided is a method for manufacturing a flame-retardant filter, which comprises a cylindrical filter by a step of bonding a cylindrical epoxy resin to form a cylindrical filter.

According to this production method of the present invention, glass filter paper pressed and reinforced with a mesh-like ETFE copolymer from both the front and back sides is folded into a pleat shape, and the sharpened tip is heated by the folding to perform reciprocal folding. By doing so, the flame-retardant filter of the present invention described above can be continuously manufactured industrially in a state where the shape is not lost.

The heating in this reciprocal folding step is 1
By carrying out at a temperature of from 0 to 120 ° C., it is possible to satisfactorily hold the tip of an acute angle that is folded and formed into a pleat shape.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. First, a method for manufacturing a flame-retardant filter will be described. FIG. 1 is a schematic view of an apparatus for manufacturing a flame retardant filter. 1 is a reel stand, and this reel stand 1 is a reel stand in which a flame-retardant material used for reinforcing the filter is wound around. The material wound around the reel stand 1 is a fluororesin made of ETFE copolymer. 10
Shows the ETFE copolymer unwound from the reel stand 1.

The resin has been developed as a fluororesin which can be melt processed and has mechanical toughness. ETFE copolymers having a wide range of compositions have been studied for a long time, but they have not been industrialized for a long time because of stress cracking. This problem has been solved by copolymerizing the third component.

The three-component copolymer can be used either in emulsion polymerization or suspension polymerization in water. ETFE is an alternating polymer in which repeating units of ethylene and tetrafluoroethylene alternate, and the alternating structure is 75% or more. Ethylene / tetrafluoroethylene one-to-one copolymer has a structure in which vinylidene fluoride isomers, that is, vinylidene fluoride is added head by head and tail by tail, but has a melting point much higher than that of polyvinylidene fluoride. , And also
It also has a low dielectric constant.

The melting point of the ETFE resin depends on the molar ratio of ethylene and tetrafluoroethylene, the degree of alternatingness, and the third
It is affected by the amount of ingredients. A typical sample shows a melting point of 270 ° C and is estimated to be 318 ° C at 100% alternation. ETFE dissolves in isoptyl adipate above 230 ° C. As the optimum reinforcing dimension of ETFE10 for reinforcing the filter paper, the wire diameter is 0.12 to 0.25 (mm) millimeters and the particle size is 20 to 60 mesh.

Reference numeral 2 is a reel stand, which is a reel stand in which a material to be a main body of the filter, that is, a glass filter paper 20 is wound. The glass filter paper 20 is a so-called high performance air cleaning filter paper made of glass fiber. The glass filter paper 20 is specified by MIL-STD MIL-F-51079C, and the capture rate of 0.3 μm (micron) dioctyl phthalate particles (abbreviation: DOP particles) is under the condition that the surface wind velocity is 5.33 cm / sec. It is specified that it is a glass fiber filter paper usually referred to as a HEPA filter, exhibiting a property of 99.97% or more. Such a glass filter paper 2
0 is adopted as the filter paper of the flame-retardant filter.

With the glass filter paper 20 fed from the reel stand 2 as the center, the ETFE 10 is fed from the reel stand 1 from the front surface and the back surface so as to sandwich the glass filter paper 20. The glass filter paper 20 and the ETFE 10 are pressed by the slitter machine 3 in the next step.

In the slitter machine 3, both sides of the glass filter paper 20 are sandwiched by the ETFE 10 and the slitter machine 3 is used.
Is passed, a single flat filter is formed. The pressed planar filter is reciprocally folded by the reciprocating folding machine 4 in the next step. In the reciprocating folding machine 4, the filter is folded into an accordion shape, that is, a pleat shape in order to increase the filtration area. The acute-angled tip portion folded in a pleated shape is heated by the heating unit in order to maintain the acute angle. The optimum temperature for heating in the heating section is 100-120 ° C.
Is.

When the heating process is completed, the filter is cut according to the number of folds required to form a cylindrical shape,
The cut surface is adhered into a cylindrical shape using a two-component epoxy resin. As shown in FIG. 3, both ends of the cylindrical filter 31 which is adhered into a cylindrical shape are covered with a lid made of SUS304 metal. The metal lid is composed of two kinds of lids, a lid 33 having the same size as the circle of the cylindrical filter 31 and having a hole 34 in the center, and a lid 32 having no hole on the entire surface. And a two-component epoxy resin is used for adhesion processing.

The cylindrical filter 31 is provided with metallic lids 32, 3
3 is bonded to complete the flame-retardant filter 30. The finished product of the flame-retardant filter 30 is a UL safety standard U relating to the combustion test of plastic materials for parts of machines and appliances.
Pass the L94 test. FIG. 2 is a sectional view of the filter material of the present invention obtained as described above. In FIG. 2, 10 is ETFE and 20 is glass filter paper.

The flame-retardant filter 30 shown in FIG. 3 is used by injecting gas through the opening of the hole 34 in the lid of the cylindrical filter 31 and passing the pleated glass filter paper through the inner cavity of the cylindrical filter 31. The gas is flown in the outer circumferential direction of the cylinder to capture dust.

The present invention has been described above based on the embodiment, but the present invention is not limited to this embodiment, and various modifications can be made within the scope of the present invention shown in the claims.
It goes without saying that modifications may be added. For example, in the above-described embodiment, as the reticulated ETFE copolymer, a combination of a wire diameter of 0.12 to 0.25 mm and a particle size of 20 to 60 mesh is used, but a combination other than this combination is used. May be adopted. Further, in the above-described embodiment, the heating in the reciprocal folding step is 1
Although it is performed at 00 to 120 ° C, it may be performed at a temperature outside this range.

[0027]

As described above, the present invention provides a filter for removing dust by passing the filter paper from the inner cavity of a cylindrical filter made of pleated glass filter paper and flowing gas in the outer peripheral direction. , 0.3 μm dioctyl phthalate particles have a capture rate of 99.9% or more under the condition that the surface wind velocity is 5.33 cm / sec, and the glass filter paper, which is usually called HEPA, is reticulated. ETF
A cylindrical filter that is sandwiched between E copolymers, reinforced and pressed from the front and back, and folded into a pleat shape to make it into a cylindrical shape.
And a flame-retardant filter, which is preferably made of SUS304 and is made of metal and has a lid with a hole in the center and a lid without a hole bonded to the end of the cylindrical filter.

The thus constructed filter according to the present invention is a flame-retardant, high-performance, safe, and high-temperature, high-humidity radioactive gas waste from a nuclear facility, which employs glass fiber filter paper satisfying the MIL standard. It is suitable for treating objects.

Further, the filter according to the present invention is ETFE.
Since the cylindrical filter is constructed by sandwiching both sides of the glass filter paper with a reinforcing material made of a mesh of a copolymer, the reinforcing material has elasticity, and it is reinforced by pressing from both sides of the glass filter paper. Even if you do not destroy the glass filter paper,
It is easy to process into pleats and does not lose its shape.

In the flame-retardant filter of the present invention, a wire diameter of 0.12 to 0.25 m as a reticulated ETFE copolymer
In the case of using a combination of m and a grain size of 20 to 60 mesh, soft glass filter paper is reinforced in optimal condition from both sides.

Further, according to the present invention, in a method for producing a filter paper for capturing dust and a pleated filter in which the front and back of the filter paper are covered with a reinforcing material, a glass filter paper and a reticulated ETFE copolymer are provided on a reel stand. Supply preparation step,
A step of sandwiching the glass filter paper from the front and back using the reticulated ETFE copolymer to press-reinforce it through a slitter machine, and folding the press-reinforced material into pleats to heat the tip of the filter into an acute angle for reciprocal folding. And a step of cutting the filter into a number of folds corresponding to the size of the circle of the filter and adhering the cut surface of the filter into a cylindrical shape using a two-component epoxy resin. Provided is a method for manufacturing a sex filter.

According to this production method of the present invention, glass filter paper pressed and reinforced with a mesh-like ETFE copolymer from both the front and back sides is folded in a pleat shape, and the sharp-edged tip is heated by the folding to perform reciprocating folding. By doing so, it is possible to continuously manufacture the flame-retardant filter of the present invention in a state in which it does not lose its shape.

The heating in this reciprocal folding step is 1
The manufacturing method carried out at 00 to 120 ° C. can favorably hold the sharp-angled tip that is folded and formed in the shape of pleats.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus for manufacturing a flame-retardant filter according to the present invention.

FIG. 2 is a cross-sectional view showing a filter material forming a flame-retardant filter according to the present invention.

FIG. 3 is a perspective view showing an example of a flame-retardant filter according to the present invention with a part cut away.

[Explanation of symbols]

1 Reel Stand 2 Reel Stand 3 Slitting Machine 4 Reciprocating Folding Machine 5 Filter 10 Ethylene / Tetrafluoroethylene (ETF
E) Copolymer 20 Glass filter paper 30 Flame-retardant filter 31 Cylindrical filter 32 Lid 33 Lid 34 Hole

Continued front page    (72) Inventor Zenji Muroshita             Osaka Prefecture Osaka City Nishiyodogawa Ward Minejima 3-629             No. Misuzu Seiko Co., Ltd. F-term (reference) 4D019 AA01 BA04 BA13 BB03 BB08                       BB10 BC11 BC12 BD10 CA02

Claims (4)

[Claims] 1. A filter for removing dust by passing a gas through an inner hollow portion of a cylindrical filter made of pleated glass filter paper and passing the filter paper in an outer peripheral direction to remove dust.
3. The capture rate of 3 μm dioctyl phthalate particles is 5.
A glass filter paper showing 99.9% or more properties under the condition of 33 cm / sec is sandwiched between ethylene / tetrafluoroethylene copolymers of reticulated fluorine resin and pressed and reinforced from the front and back, and folded into a pleat shape. A flame-retardant filter, characterized in that a cylindrical filter having a cylindrical shape, and a lid made of metal and having a hole at the center and a lid not having a hole are bonded to an end portion of the cylindrical filter. 2. The ethylene / tetrafluoroethylene copolymer of the reticulated fluorine resin has a wire diameter of 0.12 to 0.25.
The flame-retardant filter according to claim 1, which has a combination of mm and a grain size of 20 to 60 mesh. 3. A method of producing a filter paper which captures dust and a pleated shape in which the front and back surfaces of the filter paper are covered with a reinforcing material, and a glass filter paper and a reticulated ethylene / tetrafluoroethylene copolymer are provided on a reel stand. A step of preparing for supply, a step of sandwiching the glass filter paper from the front and back using the reticulated ethylene / tetrafluoroethylene copolymer to press-reinforce through a slitter machine, and a pleated shape of the press-reinforced material to form an acute angle. A step of heating and reciprocating the tip of the filter, and a step of cutting the filter into a number of folds corresponding to the size of the circle of the filter and bonding the cut surface of the filter into a cylindrical shape using a two-component epoxy resin. A method for manufacturing a flame-retardant filter, characterized in that a cylindrical filter is constituted by and. 4. The temperature of the reciprocal folding step of heating the tip of the filter to maintain an acute angle of the filter is 1
The temperature is set to 00 to 120 ° C.
A method for manufacturing a flame-retardant filter according to 1.