RU171699U1 - HEATABLE AEROSOL FILTER - Google Patents

Abstract

Refractory aerosol filter refers to aerosol filters, which are analogues of D-23 filters; D-13; D-6.5, used for the purification of process air in the radiochemical, chemical and metallurgical, chemical, electronic, medical and biotechnical industries. A flame-retardant AFG aerosol filter consists of a housing and a filter element FVA-NS, which is a separate housing, with corrugates installed inside it at an angle of at least 10 ° relative to each other, forming folds ("accordion"). The corrugations are made of corrugated filter paper based on microfine fiberglass, which does not contain substances that are harmful to the environment. The filter housing is made of plywood (type D). Plywood cases and wooden structural elements of the filter and filter element are impregnated in three layers with the Terminus-11 fire-retardant compound. The utility model provides high efficiency air purification at low energy costs.

Description

The utility model relates to the field of gaseous radioactive waste management in the nuclear industry, namely to the treatment equipment for collecting radioactive aerosols, and can be used in the electronic, chemical, medical and biotechnical industries.

Known filters D-23; D-13; D-6.5 with filtering material Petryanov’s filter (FP), which are widely used at the enterprises of the nuclear industry [TU 952314-98. Aerosol filters with filtering material FP]. The filter element in them is a folded bag in the form of a parallelepiped. Along with high technical indicators, FP filters have several disadvantages:

- relatively low thermal stability of the filter material - not more than 60 ° C;

- the filtering material is combustible; toxic substances are released during combustion;

- during the operation of the filter, a decrease in cleaning efficiency is observed with increased moisture content of the medium being cleaned or under the influence of ionizing radiation.

High-performance fireproof fine air filters of the HEPA and ULPA type are known, where glass paper based on microfine fiberglass is used as filter material [Air Filters For Use At Nuclear Facilities // Technical Reports Series. - No. 122, International Atomic Energy Agency, Vienna. - 1970; Testing And Monitoring of Off-Gas Cleanup Systems At Nuclear Facilities // Technical Reports Series. - No. 243, International Atomic Energy Agency, Vienna. - 1984; Design And Operation Of Off-Gas Cleaning Systems And High Level Liquid Waste Conditioning Facilities // Technical Reports Series. - No. 291, International Atomic Energy Agency, Vienna. - 1988]. Filters are a folded package of glass paper, poured into the walls with sealant. Such a package, especially if it is large (600-1200 mm), has little stiffness, and even the presence of separators cannot significantly increase it. This disadvantage leads to significant deformation under the influence of air load and dead weight, which, in turn, is associated with the appearance of defects in the filter layer. The design of these filters prevents their use in existing ventilation and gas purification systems of nuclear industry enterprises without their modernization and reconstruction. The latter is associated with huge economic costs, because only one enterprise operates up to several thousand filter filters.

The above disadvantages are eliminated by the use of filters of the type FTOV-SBM L- or M-shaped configuration based on glass paper and polyester, developed in the dimensions of standard filters FP [RF Patent No. 65398]. Aerosol filters consist of a wooden case and a filter element of an L- or M-shaped configuration, which is a folded package of glass paper with separation of folds by separators. The filter elements are connected to the walls of the housing using sealant. They differ from the FP filters in terms of increased heat and moisture resistance, high cleaning efficiency in humid conditions, increased dust absorption, increased filter volume utilization due to an increase in the useful filtering area of the fine air purification stage, as well as fire resistance and fire safety. These glass paper filters also eliminate the disadvantage of HEPA and ULPA filters regarding the possibility of their installation in existing cleaning systems without additional alteration.

But the design of filters with an M-shaped and L-shaped arrangement of FTOW filter elements, proposed to increase the useful filtration area, has the same main drawback as the design of HEPA and ULPA filters, namely:

- insufficient rigidity due to the large size of the filter modules (over 700 mm) included in the filter element, which was confirmed experimentally. After testing on an aerodynamic stand, wrinkles and ruptures of fiberglass were found along the perimeter of the filtering modules parallel to embedding in the aluminum profile of the frame, which greatly reduced their effectiveness. Multiple tests showed that the fiberglass-based filtering material, which is more fragile and has a lower elongation coefficient than FP materials, does not resist shear deformations, which inevitably affect the filter, filtering element and its components during testing and operation.

Additionally, when assembling the filters, it was noted by specialists that it is difficult to seal the joints of the FTOV modules with each other and with the walls of the housings due to the need to use long filter modules and a small turning angle between them for the L- or M-shaped configuration. This led to additional damage to the filter material and complicated visual inspection during the production process.

The technical task is to eliminate all the disadvantages of filters such as HEPA, ULPA, L - and M-shaped filters FTOV-SBM, namely:

- increasing the stiffness of the filter without reducing the area of the filter surface;

- an increase in the maintainability factor in the process of its assembly prior to testing;

- increase the area of the filter surface, without changing the overall dimensions of the filter.

The problem is solved by using a fine filter element type FVA-NS (configuration "accordion") in a separate housing. As constituents of the filter element, corrugates with a folded filter material of corrugated filter paper based on microfine fiberglass, installed at an angle to each other in the form of folds at an angle of at least 10 °, are used. The filter element is inserted into the AFG filter housing (Gordienko aerosol filter). For the AFG-D-6.5 filter, the length of the corrugation is 300 mm; for the AFG-D-13 filter - 350 mm; for the AFG-D-23 filter - 350 mm. The number of corrugates is assigned depending on the overall dimensions and the area of the filter surface of the filter.

Schematic representation of the proposed filter designs AFG-D-23-FVA-NS; AFG-D-13-FVA-NS; AFG-D-6,5-FVA-HC is depicted in FIG. 1, 2, 3, respectively. The principle of operation of all three proposed filters is the same: the cleaned air enters the filter housing 1, then passes through the filter element 2, equipped with corrugated bags with folded filter material based on fiberglass 3. After cleaning, the air leaves the filter. The direction of air movement is indicated by an arrow.

The main advantages of the proposed model for these filters:

- fiber glass damage is prevented when the filter is pressed into the test bench and the ventilation system, since the main (standard) housing in which the FVA-NS filter element with corrugates is installed will almost completely take on the negative effect of shear deformations.

- increased stiffness and reliability of the filter;

- increased maintainability coefficient of the filter;

- increased filter surface area, without changing the overall dimensions of the filter;

- there is the possibility of installing an additional stage of rough cleaning.

The types of developed filters AFG-FVA-NS configuration of filtering blocks in comparison with analogues are shown in table 1.

Filter housings can be made of plywood (type D). To transfer to the first group of fire-retardant efficiency, plywood cases and wooden structural elements of AFG-FVA-NS filters are impregnated in three layers with the “Terminus-11” fire-retardant composition [TU 2499-003-55171591-2005. Fire-retardant composition for wood with antiseptic action "Terminus-11"].

The test results of AFG-FVA filters based on glass paper are presented in table 2.

Thanks to the proposed technical solution:

- the stiffness and reliability of the product significantly increases due to the use of the FVA filter element (with a depth of not more than 350 mm) installed in the body of a standard filter;

- eliminates the possibility of damage to the glass paper when sealing the junction of the filter element with the housing, because sealing joints between the housings will consist in applying silicone sealant around the perimeter of the filter element FVA-NS;

- simplifies the process of assembling the filter;

- there is an additional opportunity for visual inspection of the marriage that appeared in the filter manufacturing process;

- the nominal filter performance is increased and energy costs are reduced due to a decrease in aerodynamic drag (the use of fine filter modules with a length of less than 250 mm and more than 400 mm in the filter is impractical due to a sharp increase in the aerodynamic drag of the entire filter).

Claims (4)

1. A nonflammable aerosol filter consisting of a housing and a fine filter element of glass paper, characterized in that the filter element is a housing in which corrugates are installed. 2. The aerosol filter according to claim 1, characterized in that the corrugated filter paper based on microfine fiberglass is used as components of the filter element, installed at an angle to each other in the form of folds at an angle of at least 10 °, having a certain depth: AFG-D-6.5 filter - 300 mm; for the AFG-D-13 filter - 350 mm; for the AFG-D-23 filter - 350 mm. 3. The aerosol filter according to claim 1, characterized in that the filter housing is made of plywood soaked in three layers with the Terminus-11 fire-retardant composition. 4. The aerosol filter according to claim 1, characterized in that the filter contains wooden elements impregnated in three layers with the Terminus-11 fire-retardant composition.

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