JP2003190731A - Ceramic fiber filter to prevent bypass leak - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a bypass leak in a thermally expanded state under high temperature conditions in a cassette-type air filter including a filter body, comprising a filter cloth of a wavingly folded ceramic fiber and a plurality of separators, surrounded in a rectangular parallelepiped form by upper and lower end plates and side plates provided respectively on both sides of the filter body. <P>SOLUTION: In this ceramic fiber filter, a folded part is provided on the filter cloth in its end face opposite to at least one end plate. According to this construction, upon thermal expansion of the air filter, the folded part of the filter cloth is exposed to wind pressure and consequently is widened, whereby a gap between the filter cloth and the end plate disappears and, at the same time, the folded part approaches the end plate, thereby preventing a bypass leak. A clogging plate such as a metal plate or a filter cloth may be mounted in the gap between the folded part at the end face of the filter cloth and the end plate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette type ceramic fiber filter used for high-temperature air purifiers, incinerator exhaust gas treatment, and the like, and more particularly to a ceramic fiber filter for preventing bypass leak during thermal expansion.

[0002]

2. Description of the Related Art Cassette type ceramic fiber filters are widely used as high temperature air filters.
The structure is shown in FIG.
, A large number of separators (partitions) 61, 61, ... Are inserted between the filter cloths 60 bent in a wave shape, and the filter body 65 composed of the filter cloth 60 and the separators 61 has upper and lower ends. By being surrounded by the plates 66 and 67 and the side plates 68 and 69 on both sides,
It has a rectangular parallelepiped shape. Each plate is generally made of a metal plate such as stainless steel.

When this cassette type ceramic fiber filter is used at a high temperature (250 to 800 ° C.), as shown in FIGS. 5A and 5B, due to the difference in linear expansion coefficient between the metal frame and the filter cloth (filter material). A gap S (for example, 5 to 10 mm) is created between the sealing material 66 a applied to the lower surface of the end plate 66 and the upper end of the filter cloth 60. When the fluid flows through this gap, so-called bypass leak occurs, the filtration efficiency decreases, and the substance that could not be filtered adversely affects.

Japanese Patent Laid-Open No. 2000-70641 "High temperature air filter" describes a high temperature air filter in which a core material is provided in an inorganic adhesive so that the trapping efficiency can be maintained even at high temperatures. Japanese Unexamined Patent Publication No. 8-108022 “Air filter for low dust generation and high temperature” describes a high temperature air filter in which a woven fabric made of long glass fibers is arranged on one surface on the air outflow side of a filter medium. None of the above publications describes a bypass leak due to thermal expansion. Although there are many cases in which the filter material and the seal material are fixed with an adhesive, tensile stress due to thermal expansion causes peeling, cracking, and tearing of the adhesive, resulting in a bypass leak and collection. Efficiency was often reduced.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ceramic fiber filter which prevents bypass leakage during thermal expansion at high temperature.

[0006]

The basic structure of the present invention is a filter composed of a corrugated ceramic fiber filter cloth and a plurality of separators inserted between adjacent filter cloths. The present invention relates to a cassette type air filter in which a main body is surrounded by upper and lower end plates and side plates on both sides in a rectangular parallelepiped shape. In order to achieve the above object, in the present invention, a folded-back portion is provided on the end surface of the filter cloth that faces at least one of the end plates.

[0007]

Thus, according to the cassette type air filter of the present invention, when the air filter is thermally expanded at high temperature, the folded portions receive wind pressure and spread like a bag, and the folded portions come into contact with each other. Close to the plate to prevent bypass leaks.

As a further preferred embodiment, a closing plate such as a metal plate, a filtering cloth or ceramic wool is attached to the gap between the folded-back portion of the end face of the filter cloth and the end plate facing the end surface, and the closing plate is Position to contact the filter cloth. As a result, even if a gap or dissociation occurs in the folded portion of the end face of the filter cloth, as long as the closing plate is in contact with the filter cloth, the bypass leak at the time of thermal expansion can be prevented. Hereinafter, preferred embodiments according to the present invention will be described with reference to the accompanying drawings.

[0009]

1A and 1B show a folded-back portion of a filter cloth according to the first feature of the present invention, in which a bag-shaped folded-back portion is provided on an end surface of the filter cloth 12 facing an upper end plate 66. 12a and 12b are provided, and these folded portions are folded upstream. As described above, when subjected to thermal expansion, the rate at which the ceramic fiber filter cloth 12 vertically extends is smaller than the rate at which the separator 14 made of a metal plate vertically extends, and therefore, the upper end of the filter cloth 12 and the end plate 66. There will be a gap between the bottom surface of the and.
In the present invention, the folded-back portions 12a, 1 are provided on the end surface of the filter cloth 12.
2b is provided, and the folded portion is folded upstream, so that it receives wind pressure when the fluid to be filtered flows,
As shown by the dimension E, the folded-back portions 12a and 12b are
You will bid up. Thus, the upper end of the filter cloth 12 approaches the lower surface of the end plate 66 and the sealing material 6
The contact with 6a can be maintained, and the bypass leak can be prevented. The folded-back portion may be provided on the lower end surface of the filter cloth 12 facing the lower end plate 67.

2A and 2B show a closing plate according to the second feature of the present invention, which is a metal plate, a filter cloth, or the like between the upper end of the folded portion of the end face of the filter cloth and the end plate 66 opposed thereto. The closing plate 20 made of the inorganic fiber material is disposed, and the closing plate 20 is positioned so as to contact the filter cloth 12. The closing plate 20 is attached so as to cover one fold. As described above, when subjected to thermal expansion, a gap is created between the upper end of the filter cloth 12 and the lower surface of the end plate 66, but in the present invention, the closing plate 20 keeps contact with the filter cloth. Therefore, bypass leak at the time of thermal expansion can be prevented.

3A and 3B show a preferred embodiment of the present invention, in which a gap between a folded portion of the end face of the filter cloth and the end plate 66 facing the folded portion is filled with metal plates, filter cloth, ceramic wool or the like 51, 52. , 53 are adhered with high temperature cement or fixed with a high temperature curing agent, and the filling 5
It shows an example in which 1, 52, 53 are positioned so as to contact the filter cloth 12. As a result, as long as the padding is in contact with the filter cloth, bypass leak during thermal expansion can be prevented. If necessary, it is possible to make modifications such as providing a closing plate in front of the bag-shaped folded portion, but they need to be arranged so as not to reduce the filtration efficiency.

[0012]

As described in detail above, according to the present invention, when the air filter thermally expands at high temperature, the folded portion receives wind pressure and expands like a bag to approach the end plate to prevent bypass leak. To do. Further, by providing a closing plate, the closing plate keeps contact with the filter cloth, thereby preventing bypass leak at the time of thermal expansion. Thus, the filtration efficiency does not decrease even at high temperatures, and the technical effect is extremely remarkable.

[Brief description of drawings]

FIG. 1 is a perspective view and a vertical sectional view showing a folded-back portion of a filter cloth, which is a feature of the present invention.

FIG. 2 is a vertical sectional view and a perspective view showing an example of a closing plate according to the present invention.

FIG. 3 is a vertical sectional view showing an example of a padding according to the present invention and a sectional view taken along line BB.

FIG. 4 is a perspective view showing a conventional cassette type air filter.

FIG. 5 is a vertical cross-sectional view showing a gap during thermal expansion in a conventional filter.

[Explanation of symbols]

10 Ceramic fiber filter 12 filter cloth 12a, 12b Folded part 14 Separator 20 Block 51,52,53 Stuffed 66,67 End plate 68,69 Side plate

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4D019 AA01 BA05 BB03 BC12 CA02                       CB04                 4D058 JA13 JB06 JB25 KA01 KA08                       KA27 KA30 SA20

Claims (2)

[Claims] 1. A filter body composed of a ceramic fiber filter cloth bent in a corrugated shape and a plurality of separators inserted between adjacent filter cloths is composed of upper and lower end plates and side plates on both sides. A cassette-type air filter, which is surrounded by a rectangular parallelepiped shape, wherein a folded-back portion is provided on an end surface of a filter cloth facing at least one end plate, and the folded-back portion receives wind pressure when the air filter thermally expands. A ceramic fiber filter that is blocked by expanding and is close to the end plate to prevent bypass leak. 2. A metal plate, a filter cloth, and a filter cloth in the gap between the folded-back portion of the end surface of the filter cloth and the end plate facing the end surface.
The ceramic fiber filter according to claim 1, wherein a blocking plate made of ceramic wool or the like is attached, and the blocking plate is positioned so as to contact the filter cloth.