RU2487745C1 - Sorption-filtration sandwich material and filter with such material - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to fibrous sorption-filtration materials used for cleaning from aerosols and radioactive forms of iodine. Material comprises the following layers: layer of high-porosity fibre glass nonwoven material with fibre diameter of 5-10 mcm, layer of fibrous activated carbon material, layer of fibrous carbon material impregnated with amine compound and metal iodide, and layer of thin-fibre paper glass or of nonwoven fibrous polyamide material with fibre diameter of 100-300 nm. Material is corrugated and place in filter made up of two modules. First module comprises three layers. Second module comprises layer of fine fibrous material of paper glass or polyimide.

EFFECT: better cleaning, longer life, lower costs and ease of manufacture.

7 cl

Description

The invention relates to the field of sorption-active filtering materials and filters that can be used to clean gases from aerosols, molecular iodine and its compounds, for example, in air ventilation systems in radiochemical plants and nuclear power plants.

A sorption-filtering three-layer fibrous material is known, the middle layer of which is made of ultrafine perchlorovinyl fibers containing particles of activated carbon treated with silver nitrate, or of activated carbon fibers treated with silver nitrate, and the outer layers are made of a mixture of perchlorovinyl glued together ultrafine fibers, with a diameter of 5-9 and a diameter of 0.5-1.2 microns. Based on this material, products were proposed: filters for gas purification, analytical tape and a filtering half mask (RU 2188695, 09/10/2002).

The disadvantage of this material is the non-environmentally friendly technology for producing microfiber material, associated with large emissions of dichloroethane into the atmosphere.

Known sorption-filtering material, which contains an inner layer of polypropylene microfibers with a diameter of 5-10 microns, filled with particles of activated carbon impregnated with silver nitrate, with a mass ratio of carbon to fibers equal to 1: (2-4), and outer layers consisting from thermally bonded polypropylene microfibers, with nanofibers with a diameter of 100-300 nm deposited on them, obtained by electrospinning from a solution of a mixture of chlorinated polyvinyl chloride and butadiene-nitrile rubber based on butylac etata. The material is effective for the absorption of radioactive iodine (RU 2414960, 03/27/2011).

Known aerosol sorbent filter containing a housing in which the filter element is placed, made of a zigzag folded multilayer filter material of fiberglass with separating separators located between the folds, while the layers of the filter material, except for the last along the cleaned air stream, contain particles of finely ground highly porous sorbent - activated carbon with a particle diameter of 1-100 μm in an amount of 10-500 g / m ² (RU 2192914, 20.11.2002).

A known filter for air purification from radioactive iodine, containing a multilayer material, in which the first layer along the filtered air made of activated carbon fiber material with a surface density of at least 200 g / m ² , then layers made of a material containing particles of highly porous sorbent, impregnated with potassium iodide, tertiary amine, silver nitrate and / or barium iodide in an amount of not more than 10%, and the last layer made of a thin fiber material containing no sorbent, and eyuschy packing density of not more than 0,06 (RU 2262758 10.05.2005).

The disadvantages of the above materials are the presence in them of powdery particles of sorption materials - coal, leading to increased aerodynamic resistance of the material, the possible formation of dust and its entrainment.

The closest in technical essence and the achieved result is a sorption-filtering material and a filter based on it for air purification from aerosols and radioactive iodine compounds, while the material includes sequentially containing layers of fabric from fibers of activated carbon material with a fiber diameter of 2-10 μm, and fabrics made of carbon fiber material impregnated with a compound of amine and / or potassium iodide (RU 2161338, 12.27.2000).

However, the known material and the filter based on it have an increased aerodynamic drag, provide an insufficient degree of purification from impurities of aerosols and dust. In addition, the known sorption-filtering material has a low tensile strength.

The objective of the claimed group of inventions is to develop a sorption-filtering material having a high capacity in relation to radioactive aerosols, molecular iodine and its organic compounds, and a filter design that provides increased strength and low aerodynamic resistance of the material during operation.

The problem is solved by the described sorption-filtering multilayer material intended for the purification of gaseous media from radioactive aerosols, molecular iodine and its compounds, which contains sequentially placed layers: a layer made of highly porous glass fiber nonwoven material with a fiber diameter of 5-10 μm, a layer of fibrous activated carbon material, a layer of fibrous carbon material impregnated with a compound of amine and metal iodide, a layer of fine fiber glass paper gi or a layer of non-woven fibrous material obtained by electrospinning from a solution of polyamide having a fiber diameter of 100-300 nm.

Preferably, the fibrous carbon impregnated material has a surface density of 140-170 g / m ² and is impregnated with triethanolamine and potassium or barium iodide.

The sorption-filtering multilayer material may also further comprise a layer made of a non-woven fibrous polyester material with a fiber diameter of 10-50 μm, which is placed first along the cleaned gas medium.

The problem is also solved by the described filter for cleaning gaseous media from aerosols, molecular iodine and its compounds, which contains a housing equipped with means for entering and exiting the gaseous medium, and sorption-filtering material described above, and the material is placed in the filter housing in the form of two modules, of which the first module contains a layer made of highly porous fiberglass nonwoven material, a layer of fibrous activated carbon material and a layer of fibrous carbon the impregnated material, and the second module comprises a layer of fine fiber glass paper or layer of nonwoven fibrous material obtained by electrospinning of nylon solution.

Preferably, the sorption-filtering material is laid in the filter housing to form a pleated structure.

Preferably, the layers in the first module are separated by spacers made in the form of a mesh of corrosion resistant metal, with a mesh thickness of not more than 0.5 mm and a mesh cell size of not more than 30 × 30 mm.

The filter may be further provided with a removable insert containing a layer of non-woven fibrous polyester material with a fiber diameter of 10-50 μm, having a thickness of not more than 20 mm

The above set of features allows you to provide the claimed technical result. The presence in the first module of a layer of highly porous glass fiber non-woven material with a fiber diameter of 5-10 μm, which is chemically resistant, non-combustible and highly porous, provides preliminary cleaning of the gas from dust particles, including particles having a high temperature. The use of triethanolamine potassium or barium iodide as an impregnating substance increases the sorption properties of the fibrous carbon material, and also helps to increase the service life, especially at elevated temperatures. The surface density of the impregnated carbon fiber layer, equal to 140-170 g / m ² , is optimal for achieving high capacity for iodine and its compounds with low aerodynamic drag. The use of separators in the filter also reduces aerodynamic drag. Placing the material in the filter housing in the form of two modules eliminates the damage to the surface of fine-fibrous materials (glass paper and polyamide material) in case of an emergency, while the materials used in the second module with the stated arrangement of the layers provide a high degree of purification of the gaseous medium from aerosol particles. Additional supply of the filter with a removable insert containing polyester material provides gas pre-treatment, which is desirable in case of high dustiness of the gas stream. The presence of two modules in the filter facilitates the technology of its assembly, and reduces the cost of the filter.

The assembly of the claimed sorption-filtering material and its placement in the filter is as follows:

Example 1

At the first stage, the sorption-filtering material is assembled, which will be equipped with the first filter module. For this purpose, a layer of highly porous non-woven fiber glass material with fiber diameter of 5-10 microns and a surface density of 40 g / m ² is applied a layer of fibrous activated carbon material with a diameter of 20-25 microns and fiber areal density of 150 g / m ^2. Then impose a layer of fibrous carbon material with a fiber diameter of 20-25 μm and a surface density of 150 g / m ² impregnated with triethanolamine in a mixture with KI at the rate of 8% wt. by weight of carbon material. Then the material is corrugated and a separator is placed between the layers, made in the form of a corrugated mesh with a thickness of 0.5 mm and a mesh size of 30 × 30 mm. After that, the first module is inserted into the filter housing and sealed at the joints. Then carry out the assembly of the second module. For this, a layer of fine fiber glass paper with a fiber diameter of 0.3-0.6 μm and 7-10 μm and a surface density of 70 g / m ^{2 is} corrugated and a separator is laid between the layers, made in the form of a corrugated mesh with a thickness of 0.5 mm and a mesh size 30 × 30 mm. After that, the resulting module is inserted into the filter housing, placed directly behind the first module in the direction of air flow, and sealed at the joints.

Example 2

At the first stage, material is assembled for the first module. For this purpose, a layer of highly porous non-woven fiber glass material with fiber diameter of 5-10 microns and a surface density of 40 g / m ² is applied a layer of fibrous activated carbon material with a diameter of 20-25 microns and fiber areal density of 150 g / m ^2. Then impose a layer of fibrous carbon material with a fiber diameter of 20-25 μm and a surface density of 150 g / m ² impregnated with triethanolamine in a mixture with BaI ₂ at the rate of 8% wt. by weight of carbon material. The layers are corrugated and a separator is laid between the layers, made in the form of a corrugated mesh with a thickness of 0.4 mm and a mesh size of 25 × 25 mm. Thus prepared material is placed in the filter housing and sealed at the joints. Next, a layer of non-woven fibrous material obtained by electroforming from a solution of polyamide having a fiber diameter of 100-300 nm and a surface density of 40 g / m ^{2 is} corrugated and a separator made in the form of a corrugated mesh with a thickness of 0.4 mm and a cell size is placed between the layers 25 × 25 mm. The prepared module is placed in the filter housing behind the first module along the air and is also sealed at the joints.

Example 3

The filter material is assembled as in example 2. At the inlet of the filter of example 2, a removable insert containing a layer of non-woven fibrous polyester material with a fiber diameter of 20-30 μm, a thickness of 20 mm is placed.

Filters according to pr.1 and 2 are tested in the process of purification of a gaseous medium.

The cleaned air contains: 1 mg / m ^{3 of} atmospheric dust with a particle diameter of 0.15-2 microns (more than 95%). The measurement of particle concentration was determined using a laser aerosol spectrometer LAS-P. The concentration of compounds of radioactive iodine is 10 ⁵ Bq / m ³ . Volumetric activity was measured on a gamma spectrometer.

A stream of contaminated air is passed through the filter at a space velocity of 3000 m ³ / h. The initial aerodynamic drag of the filter was 790 Pa.

The filter tests of example 3 were carried out under the same conditions as in pr 1 and 2, however, the dust content of the air was 10 mg / m ³ .

The filter test results are presented in table 1.

Table 1 Example No. Temperature ° C Relative humidity, % The efficiency of filtering particles with a diameter of 0.3 μm,% The efficiency of cleaning compounds of radioactive iodine,% one 23 67 99.98 99.65 2 22 70 99.95 99.92 3 22 68 99.96 99.75

Tests showed that the cleaning efficiency is not lower than the data obtained in example 1, despite the high dust content of the medium being cleaned, 10 times higher than the dust content of the air in examples 1 and 2.

Thus, the claimed sorption-filtering material and a filter based on it showed a high efficiency of trapping radioactive aerosols and radioactive iodine and an acceptable aerodynamic drag. The claimed filter is recommended for use in cleaning systems of nuclear power plants.

Claims (7)

1. Sorption-filtering multilayer material intended for the purification of gaseous media from aerosols, molecular iodine and its compounds, containing successively placed layers of fibrous activated carbon material and fibrous carbon material impregnated with a compound of amine and metal iodide, characterized in that before the layer of fibrous activated carbon material placed a layer made of highly porous fiberglass non-woven material with a fiber diameter of 5-10 microns, and after a layer of fibrous carbon impregnated material placed a layer of fine fiber glass paper or a layer of non-woven fibrous material obtained by electrospinning from a solution of polyamide and having a fiber diameter of 100-300 nm. 2. Sorption-filtering multilayer material according to claim 1, characterized in that the fibrous carbon impregnated material has a surface density of 140-170 g / m ² , while the material is impregnated with triethanolamine and potassium or barium iodide. 3. Sorption-filtering multilayer material according to claim 1, characterized in that it further comprises a layer made of non-woven fibrous polyester material with a fiber diameter of 10-50 μm and placed first along the cleaned gas medium. 4. A filter for cleaning gaseous media from aerosols, molecular iodine and its compounds, comprising a housing equipped with means for entering and exiting a gaseous medium and a material characterized according to claims 1-3, which is placed in the filter housing in the form of two modules, wherein the first module contains a layer made of highly porous fiberglass nonwoven material, a layer of fibrous activated carbon material and a layer of fibrous carbon impregnated material, and the second module contains a layer of fine fiber glass paper or a layer of non-woven fibrous material obtained by electroforming from a solution of polyamide. 5. The filter according to claim 4, characterized in that the sorption-filtering material is laid in the filter housing with the formation of a corrugated structure. 6. The filter according to claim 4, characterized in that the layers in the first module are separated by separators made in the form of a mesh of metal resistant to corrosion, with a mesh thickness of not more than 0.5 mm with a mesh cell size of not more than 30 × 30 mm 7. The filter according to claim 4, characterized in that at the inlet it is equipped with a removable insert containing a layer of non-woven fibrous polyester material with a fiber diameter of 10-50 μm with a layer thickness of not more than 20 mm