JP3470104B2 - Ceramic fiber filter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter structure using ceramic fiber (ceramic fiber), and more particularly, to a filter structure suitable for use in an exhaust gas treatment of an incineration facility of a nuclear facility. Regarding filters. 2. Description of the Related Art Generally, incinerators of nuclear facilities are equipped with a high-performance air filter (HEPA filter) in an exhaust gas treatment system in order to prevent radioactive substances in combustion exhaust gas from being released to the environment. However, the HEPA filter becomes clogged in a short period of time if there is a large amount of soot and dust, so that a dust removal device having a high removal efficiency is required at the preceding stage. At present, a high-temperature filter called a ceramic filter (a filter using a filter material obtained by sintering a ceramic powder into a cylindrical shape) is often used as a dust removing device. [0003] However, ceramic filters have many problems as follows. 1) The filter medium used in the ceramic filter is obtained by sintering ceramic powder such as cordierite or silicon carbide into a cylindrical shape at a sintering temperature of about 1200 to 1600 ° C. For this reason, cracks and a decrease in strength occur due to thermal shock caused by unburned combustion accumulated on the filter surface, thermal shock caused by gas temperature fluctuation caused by starting and stopping, thermal shock caused by gas temperature fluctuation caused by backwashing, and the like. [0004] 2) Since the filter medium used in the ceramic filter is obtained by sintering ceramic powder into a cylindrical shape, the pressure loss is large due to its structure. Therefore, the power load increases. When the backwash is performed, the filter differential pressure does not recover to the initial state. 3) SiC used for the ceramic filter is expensive. Since it is undeniable that the filtering effect may be lost due to cracking of the ceramic filter during use, it is necessary for nuclear facilities to replace all filters at annual inspections from the viewpoint of preventive maintenance. The running cost is very high because the unit price of the filter medium is high. Also, the used filter becomes secondary waste, and its disposal poses a problem. 4) Since the differential pressure of the filter rises quickly and the backwash interval is short, it is necessary to backwash during the incineration operation. 5) Backwash during incineration operation is a disturbance of negative pressure control in the system. 6) Filters using ceramic fibers (ceramic fibers) cannot be backwashed due to strength issues.
Frequent replacements increase running costs. Japanese Patent Application Laid-Open No. 9-285710, entitled "Ceramic Filter, Method for Producing the Same, and Apparatus Using the Same" discloses that a porous ceramic is heated with a ceramic heating element in order to prevent the destruction of the ceramic due to thermal shock and to enhance reliability. A method of compounding and a dust removing device using the method are described. JP-A-9-38432 "Ceramic filter"
Discloses a ceramic filter having a honeycomb structure in which openings for introducing and discharging a liquid containing impurities are alternately sealed as a ceramic filter having excellent filtration efficiency and a high filtration speed. JP-A-7-6
No. 0037 “Ceramic filter material and method for producing the same” describes a ceramic filter material in which a ceramic particle layer is formed on one side of a supporting base material formed from ceramic fibers and a method for producing the same. SUMMARY OF THE INVENTION An object of the present invention is to provide a filter having a novel structure which eliminates the drawbacks of the conventional ceramic filter, and in particular, does not cause cracks.
An object of the present invention is to provide a high-temperature filter which enables efficient backwashing and reduces running costs. According to a first aspect of the present invention, there is provided a ceramic fiber filter in which a fibrous ceramic fiber containing about 50% of alumina and silica is plain woven together with a reinforcing core wire. A pleated filter medium formed by bending the filter medium into a waveform and forming a pleated structure, a metal separator inserted into a gap between the waveforms of the pleated filter medium, and storing the pleated filter medium and the metal separator And a metal plate that abuts against the back side of the corrugation of the pleated filter medium.
At the top (tip side) of the metal separator, R
The pleated structure increases the filtration area and does not concentrate thermal stress on the folds of the filter media.
It is characterized in that the the like. According to the present invention, a compact, low-pressure-drop, inexpensive high-temperature filter is provided by molding a ceramic fiber containing a core wire (for example, made of SUS) into a pleated structure and increasing the filtration area. Pleated filter media has no risk of cracking like conventional ceramic filter media,
Longer life due to physical conditions and higher reliability.
In addition, since the filter medium has a pleated structure including a core wire, the filtration area increases, the filtration passage speed decreases, and the pressure loss decreases. Since no SiC is required unlike the conventional ceramic filter, the cost of the filter medium is reduced. A metal separator is disposed in order to maintain the shape of the filter medium portion and increase the strength of the structure. However, if a metal mesh separator is used as the metal separator, it is possible to effectively prevent dust and the like adhering to the surface of the filter medium. Washing becomes possible. In addition, it is considered that the folds of the filter media may be thermally degraded and damaged due to long-term exposure to a high-temperature atmosphere .
R on the top (tip side) of the separator or wire mesh separator
(Radial bending) processing is performed, so thermal stress
Can be avoided. As a modification of the ceramic fiber filter according to the present invention, as a modification, a filter medium is formed by weaving a fibrous ceramic fiber containing about 50% each of alumina and silica together with a reinforcing core wire, and this filter medium is folded into a waveform. Pleated filter material formed into a pleated structure, a round bar-shaped metal separator inserted on the back side of each fold portion of the corrugation of the pleated filter material, and a metal plate supporting an end of the round bar-shaped metal separator With frame material,
The pleated structure has a large filtering area. The ceramic fiber filter according to the present invention enables efficient backwashing by taking these measures. The filter body weighs about 30k as an example.
g, the external dimensions are about 300 × 300 × 600 mm. As for the specifications of the ceramic fiber, the maximum operating temperature is 1200 ° C, and the chemical components are alumina and silica 50 each.
%. Hereinafter, preferred embodiments according to the present invention will be described with reference to the accompanying drawings. 1A and 1B show a filter medium portion 10 of a ceramic fiber filter according to a first preferred embodiment of the present invention, in which a pleated filter medium 12 and a metal separator 14 are shown. And Pleated filter media 1
No. 2 forms a filter medium in which fibrous ceramic fibers each containing about 50% of alumina and silica are plain-woven together with a reinforcing core wire, and this filter medium is bent into a waveform to form a pleated structure. A metal separator 14 is inserted in the corrugated gap of the pleated filter medium 12.
In the example of FIG. 1, the separator 14 is formed of a metal member,
Acts as a reinforcement. Thus, the filtering area of the filter medium 12 is increased by such a pleated structure. The exhaust gas is fed into the filter medium section 10 from the direction of arrow G in FIG. 1A, and as shown in FIG. 1B, the dust F adheres to and is captured by the filter medium 12 made of ceramic fiber. The passing speed at this time is, for example, about 2 cm.
/ S. In FIG. 1B, the top portion 14a of the metal separator abutting against the back side of the fold of the corrugation of the filter medium 12
, As thermal stresses in the folds of the filter medium of the waveform is not concentrated R
Processing has been done. FIGS. 2A to 2C show an application example in which a ceramic fiber filter assembly 20 in which a ceramic fiber filter medium portion 10 is housed in outer plates 16 and 18 is formed. The ends of the outer plates 16 and 18 are folded back, and packing is adhered so that the surfaces of the folded portions 22 and 24 become a sealing surface with a mating flange surface (not shown).
This packing is preferably made of ceramic. A member having heat resistance, for example, a reinforcing member 26 made of SUS310S or the like is attached to the filter medium portion 10 in order to prevent deformation due to thermal stress. The filter medium of the filter medium section 10 is made of ceramic fiber, and the separator is made of a heat-resistant member, for example, a metal such as SUS310S. The exhaust gas flows in the direction of arrow G from the inside of the upper folded portion 22 to the inside of the lower folded portion 24 in FIG. 2A, and the radioactive dust is filtered. The external dimensions of the filter 20 are such that the width W is about 300 mm and the depth D is about 300 m
m and height H are about 600 mm. FIG. 2B shows a filter 30 according to another embodiment.
In this example, a filter medium 32 made of ceramic fiber and a mesh separator 34 made of a metal wire mesh are used. Mesh separator 34
R (bent) is provided so that the top of the mark has the same shape as the fold of the waveform of the filter medium 32. Backwash air is arrow S
, The backwash air passes through the mesh separator 34 and is sprayed uniformly on the surface of the filter medium 32, so that the dust F adhered to the surface of the filter medium is reliably removed. FIG. 2C shows a cross section of a filter 40 according to still another embodiment. In this example, a filter medium 42 made of ceramic fiber and a circle supporting the corrugated portions of the filter medium 42 from behind are supported. It comprises a bar-shaped reinforcing member 44 and a round bar-shaped frame member 46 for fixing an end of the reinforcing member 44. The round bar-shaped reinforcing member 44 functions to prevent the fold portion of the filter medium 42 from being deteriorated and bent by heat. When the backwash air flows in the direction of the arrow S, the backwash air flows through a large gap between the round bar-shaped reinforcing members 44, so that the backwash effect is high, and the dust adhering to the surface of the filter medium 42 is high. F will surely be paid off. As another embodiment, a separator corrugated so as to follow the waveform of the filter medium may be used. As described in detail above, according to the ceramic fiber filter of the present invention, there is provided a filter having a novel structure which eliminates many disadvantages of the conventional ceramic filter, and particularly, a crack caused by thermal shock. The technical effect is extremely remarkable, for example, there is no occurrence, the pressure loss is reduced, efficient backwashing is possible, and the running cost is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a structure of a pleated filter medium and a separator in the present invention. FIG. 2 is a perspective view showing an assembly and a sectional structure of a ceramic fiber filter according to the present invention. DESCRIPTION OF SYMBOLS 10 Filter media part 20, 30, 40 Ceramic fiber filter 12, 32, 42 Pleated filter media 14, 34 Separator 16, 18 Outer plate 22, 24 Outer plate folded portion 26 Reinforcement 44 Reinforcement 46 Frame material

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Yasuo Yajima               1-8-1 Kita Shinjuku, Shinjuku-ku, Tokyo               Shikinari Institute                (56) References JP-A-57-61997 (JP, A)                 JP-A-61-28415 (JP, A)                 JP-A-63-287522 (JP, A)                 JP-A-50-106854 (JP, A)                 JP-A 1-224019 (JP, A)                 JP-A-6-79119 (JP, A)                 50-111776 (JP, U)

Claims (1)

(57) [Claims 1] A filter medium is formed by weaving a fibrous ceramic fiber containing about 50% each of alumina and silica together with a reinforcing core wire in a plain weave, and this filter medium is bent into a corrugated form to be pleated. a pleated filter medium formed into structures, and metal separators which are inserted into the gap of the pleated filter medium wave, and an outer plate housing the metal separator and the pleated filter medium, the pleated filter medium wave The metal that comes in contact with the back side of the
The top of the separator has a radial bend.
Ri, filter media with a large filtration area by pleated structure
A ceramic fiber filter characterized in that thermal stress is not concentrated on the fold .