Aerosol absorption filter and the manufacturing method

 

(57) Abstract:

Aerosol absorption filter includes a housing, which houses a zigzag folded filter material, the folds of which is inserted a comma-separators of corrugated aluminum sheet. The filter material is made of krupnorogatogo material containing finely dispersed sorbent with highly porous particles with a diameter of 1-100 μm, Packed in layers. The last in the course of the cleaned air flow layer, this material is made of fine material and does not contain sorbent. The use of such a filter allows you to simplify the complex process of air purification, so as simultaneously possesses the properties of highly fileimage aerosol filter, absorbent iodides, high-efficiency for aerosols and high molecular iodine and its organic compounds. 2 S. and 6 C.p. f-crystals, 2 ill., table 1.

The invention relates to techniques for gas cleaning by filtration, including radioactive and highly toxic chemicals, more specifically to devices for separating aerosol particles and adsorption of molecular compounds of the filter material designed for Blarney form and can be used in gas cleaning systems of nuclear reactors and other facilities, operation of which leads to contamination of the gas environment by radioactive substances.

The operation of nuclear reactors, reprocessing and disposal of nuclear fuel and other objects, which are associated with the use of radioactive substances, poses numerous problems, due to the need for protection of personnel, population and environment from radioactive contamination.

Intake of radionuclides in air and process gas environment occurs both in normal manufacturing processes, and in emergency situations, when emissions of radionuclides can be particularly significant.

In this case, the radionuclides enter the air in the form of aerosols, i.e., solid and liquid particles containing radionuclides, and in the form of gaseous and vaporous molecular compounds, which are then partially deposited on aerosol particles.

The size of aerosol particles contained in the underlying clean air nuclear and other enterprises, and also in the fresh air, lie in a wide range of the s from fractions of a micrometer up to 3-5 micrometers. Mass concentration of aerosol particles, typically 0.05-0.5 mg/m3but can reach values of several g/m3. The radioactivity of the individual particles is usually 1-100 BC, but the individual particles can be active in the tens and hundreds of Becquerel.

Radionuclides in gaseous(or vapor form are radioactive noble gases and vapours of iodine, rhenium and some other radionuclides and a couple of their volatile compounds, such as CH3J - methyliodide.

The main danger of a pair of elementary radioiodide and a couple of their organic compounds - methyliodide.

Thus, to reduce the content of radionuclides in air from nuclear enterprises and reduce their emission into the atmosphere, especially during accidents, nuclear plant must be highly reliable exhaust flow recirculation air purification system operating in a normal mode of operation of the enterprise, and in terms of accidents, and provide clearance from radioactive aerosols and radioitem.

Nuclear plants typically use two-stage cleaning system, consisting of viscoity iodine purification are, typically, the device, in which the sorbent is placed in the camera box type, divided into sections, filled with granules of adsorbent. As a sorbent in most cases used granules of active carbon with a size of about 1-2 mm, impregnated with various chemical compounds, providing hammarbya molecular iodine and / or methyliodide [Patent Germany 3129384, CL 01 D 46/30, 53/00 announced. 25.07.1981, publ. 24.02.1983; Patent Germany 2149604, CL G 21 F 9/00, B 01 D 46/34 announced. 19.04.1964, publ. 30.10.1975].

Filter-adsorbers with a granular sorbent have a number of disadvantages.

First, when the grain size of 1-2 mm, the ratio of the area of geometric surface of the granules to their small mass, the result is to ensure high efficiency of the adsorber requires a large mass of sorbent, which leads to high aerodynamic resistance of the adsorber and, consequently, high cost of operation of the adsorber. So, for example, used in Russia iodine adsorber AYU-1500 [Adsorber coal AYU-1500-1, passport AND B, G. Birch, 1995 ] contains about 250 kg of coal sorbent has a capacity of 1500 m3/h and its aerodynamic resistance reaches 2500 PA.

Secondly, the truth leads to the formation of dust, which is partly carried away and partly remains in the adsorber, clogs the channels between the granules and thereby dramatically increases aerodynamic drag, making it ultimately unworkable. Removal of dust adsorber, i.e., small particles of sorbent containing radionuclides, requires the installation of another aerosol filter, which further increases the manufacturing cost and the cost of operation of the cleaning system.

Thirdly, the utilization of overage health of the filter-adsorber with a large number of granular sorbent very expensive. Its value ten times higher than the cost of disposal of aerosol filter the same performance.

Known filter unit for cleaning the air of nuclear installations from radioactive substances [French Patent 2473348, CL G 21 F 9/02, B 01 D 46/42 announced. 09.01.81, publ. 17.07.81] , which consists of two series connected standard container, one of which is placed granulated or powdered filter layer, and the other solid filter material, both of the container is connected to the air channel.

In addition to the disadvantages that are inherent filter> Known aerosol absorptive filter, comprising a housing which contains a filter element made of zigzag folded multilayer filter material containing finely dispersed particles of carbon, and located between the folds separators-separators [Y. N. Filatov. "Electropermanent fibrous materials (EFV-process)", M. 1997, pages 254-259, 198-203].

However, the capacity of such a small filter and high dust cleaned air containing molecular iodine and especially its organic compounds, it is not efficient enough. The filter is quickly filled with iodides and other aerosol particles with sizes less than 1 μm, containing Radiohead, can pass through the pores of the filter material. The present invention is to improve the efficiency of air cleaning from aerosols containing molecular iodine and its organic compounds by increasing the capacity of the filter, absorbent iodides, as well as simplifying the process of a comprehensive air cleaning and filter design.

The problem is solved in that the aerosol absorption filter, comprising a housing which contains a filter element,polozhennymi between the folds separators-separators, all layers krupnorogatogo of the filter material, except the last in the course of the cleaned air flow, contain finely ground particles of the sorbent with a diameter of 1-100 μm in the amount of 10-500 g/m2and during the last layer of cleaned air stream is made of fine material, not containing sorbent with a packing density of not more than 0,06.

For thermal stability of the filter as the filter material is a glass, and as finely milled sorbent particles impregnated activated carbon.

For the rational organization of the receipt of the flow in the filter is installed between the folds of the zigzag folded filter material separators-separators made of corrugated aluminum sheet.

The problem is solved in that the filter is made in a way that is that is placed in the housing zigzag folded, pre-Packed in layers of fibrous filter material, and placed in the folds separators-separators, all layers except the last in the course of the purified stream is made of a filtering material, which is injected cha is chesemore air layer made of a not containing particles of sorbent filter material, the packing density is not more than 0,06.

To introduce the particles of sorbent in the filter material can flow of air at a rate of 0.5-1.0 m/s, aimed directly at the filter, with simultaneous vibration of the filter housing with a frequency of 100-1000 Hz.

Comparative analysis with the prototype showed that the proposed filter is different from the known fact that all layers krupnorogatogo of the filter material, except the last, contain finely ground particles of the sorbent with a diameter of 1-100 μm in the amount of 10-500 g/m2a highly porous material, and the last layer in the course of the purified air stream is made of fine material, not containing sorbent material, the packing density of not more than 0.06, which allows to judge the criterion of "novelty."

The invention consists in the following.

To filter performed both highly effective aerosol filter and functions of the adsorber vapor molecular radioiodine and vapours of organic compounds radioiodine proposed to use superfine with highly porous particles with a diameter of 1-100 μm, previously entered or input into a ready-made filter in one or more layers of highly porous vysokoperedelnogo m aerosol particles smaller than 0.5 micron, proposed to add a sorbent material with a layer of high-quality filter material, providing high filtration efficiency the most penetrating particle size of 0.2-0.4 μm.

Of multilayer sorption-filtering material you can create a filter-adsorber separator of the type in which the material is placed in a hard case folds separated aluminum corrugated plate that allows you to have a relatively small amount of filter developed surface of the material a large area. This leads to the fact that at very large flow of air through the filter, the flow rate through the filter surface is small - of the order of several centimeters per second, which means at the same time and high efficiency filtration of aerosols, high efficiency vapor sorption of organic compounds radioitem and low aerodynamic resistance of the filter as a whole. The use of highly porous vysokoperedelnogo material in the first layer allows you to have a filter rather large dust capacity.

The invention is illustrated by drawings, where Fig.1 shows a General diagram of the device, and Fig.2 - fragment filter the masonry which is placed a separator 3 made of corrugated aluminum sheet. The filter material is made of krupnorogatogo material 4 containing highly dispersed sorbent with highly porous particles with a diameter of 1-100 μm, Packed in layers. The last in the course of the cleaned air flow layer 5 in this material is made of not containing sorbent material, the packing density of the fibers is 0.06.

Such a filter can be manufactured as follows. 4 material containing particles of sorbent Packed in layers, attached to the multilayer material, the latter layer 5 of a material not containing the sorbent, with a packing density of the fibers is 0.06, fold the material zig-zag, fold insert corrugated aluminum sheets and such a filter element accommodated in the housing 1. Fold the side edges of the material 2 and the side edges of the corrugated plate separators rigidly attached (e.g. glued) to the two inner surfaces of the housing 1. The outer surfaces of the first and last pleats also glued to the other two internal surfaces of the filter. Untreated air enters the filter through the grooves of the corrugation troughs of the input separators-separators and after passing through the material covering the cage with the two sides of novolakskogo material with particles of the sorbent can be used pre-made, for example, by blowing air containing finely powdered sorbent, through the fibrous material superimposed on the material or the flow vibration [RF Patent 2114681, CL 01 D 39/00 announced. 17.07.96, publ. 10.07.98, 19].

However, the use of material obtained in this way can sometimes lead to a decrease in filtration efficiency as a whole, since the change rate of the purified gas stream is possible blowing of the material particles of the sorbent.

To manufacture such a filter is possible and in another way, which is that in the case place multilayer material without sorbent and the sorbent is injected directly into the filter with the air flow at a rate of 0.5-1.0 m/s In this case, all the particles of sorbent to be in the first few layers krupnorogatogo material.

In the last layer of fine material, the packing density is not more than 0,06, in which the pore size is comparable to the diameter of the fibers, the sorbent particles no larger than 1 μm does not penetrate. For more uniform distribution of particles of a sorbent material layers, except the last one, the filter is subjected to vibration with a frequency of 100-1000 Hz simultaneously with the blowing air with particles of sorbent.

X The claimed aerosol absorption filter can be used in a highly efficient multi-stage cleaning systems as iodine level. Its high efficiency filtration of aerosols and high dust holding capacity allow it to be used as stages for coarse and fine cleaning and eliminate useless aerosol last step. While the resulting cleaning system may comprise a step of separating condensed moisture and two or even three aerosol-sorbing filter.

The filtration efficiency of the system and the efficiency of sorption of vapor and organic compounds radioiodine be very high and its low aerodynamic resistance. Pleeease of this system is ensured by the capacity of the first aerosol-sorbing filter. System capacity for iodine and thus resource efficiency, which is entirely determined by the resource efficiency of iodine level increases with the increase in the number of aerosol absorption filters in it.

A significant advantage of generated aerosol absorptive filter is also the possibility of its use (with appropriate dimensions) instead of the aerosol filter, widely used in present systems, air purification from radioactive aerosols, while not required per the Lema the abrasion of the sorbent. Ash particles of sorbent excluded, as the last layer is highly effective for aerosol particles of all sizes.

The problem of disposal of spent the resource efficiency of the filter is exactly the same as the problem of disposal of conventional aerosol filters, which is solved them by crushing in a small volume and disposal. The cost of manufacture and operation of the designed filter is comparable, though slightly higher, with similar values for aerosol filters of the same class (for aerosols) and the same performance.

1. Aerosol absorption filter, comprising a housing which contains a filter element made of zigzag folded multilayer filter material located between the folds of the separator separators, characterized in that all layers krupnorogatogo of the filter material, except the last in the course of the cleaned air flow, contain finely ground particles of highly porous sorbent with a diameter of 1-100 μm in the amount of 10-500 g/m2and the last layer in the course of the purified air stream is made of fine material, not containing sorbent with a packing density of not more than 0,06.

3. Aerosol absorption filter under item 1, characterized in that as finely milled sorbent particles used impregnated active carbon.

4. Aerosol absorption filter under item 1, characterized in that the separators separators are made in the form of corrugated sheet metal.

5. Aerosol absorption filter under item 1, characterized in that the separators separators are made of corrugated aluminum sheet.

6. The method of manufacture of aerosol absorption filter PP. 1-5, including accommodation in the case of the zigzag folded and Packed in layers of the filter material, the installation between the folds separators-separators, characterized in that all layers except the last in the course of the purified stream is made of a filtering material, which is injected finely ground particles of the sorbent with a diameter of 1-100 μm in the amount of 10-500 g/m2and the last during the flow of cleaned air layer made of a not containing particles of sorbent filter material, the packing density is not more than 0,06.

7. The method of manufacture of aerosol absorption filter on p. 6, characterized by the fact that all sairastui 0.5-1.0 m/s, aimed directly at the filter, particles of crushed sorbent with simultaneous vibration of the filter body.

8. The method of manufacture of aerosol absorption filter under item 7, characterized in that the filter is subjected to vibration with a frequency of 100-1000 Hz.

 

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EFFECT: the invention improves the capability of filtering oily aerosols.

19 cl, 16 tbl, 19 dwg, 23 ex

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