RU2472569C2 - Gas-and-dust separator filter for particles and aerosols - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to air cleaning filters to be used in whatever industry, aircraft engineering, air conditioning, or for engine exhaust cleaning. Filter of particles and aerosols with increased adhesion comprises dirty air inlet branch pipe, cleaned air discharge branch pipe, and cartridge with filtration elements. Front layer in said cartridge comprises mullite-silica cardboard while last layer comprises hydrophobic zeolite.

EFFECT: simplified filter regeneration, longer life, fire safety.

1 dwg, 2 ex

Description

The invention relates to filters in air purification devices. It is intended for use in various industries, aviation, for protection against toxic substances, for air conditioning of residential and industrial buildings, closed facilities. The proposed filter dust and gas separator can be used, for example, for a kitchen air cleaner in a residential area or for cleaning exhaust from engines.

The content of particles and aerosols with increased adhesion (sticky) in household dust is usually small (no more than 2-5%). As a rule, such dust is formed during the heat treatment or burning of organic substances and spreads in the form of fine oil mist, smoke, fumes, soot, tobacco smoke, soot and so on. At the same time, the formation of such dust is accompanied by the release of gaseous components, usually fixed by smell. Sticky dust is firmly held in the filter volume and during its regeneration, for example, by reverse blowing is not removed, it remains in it, gradually accumulating. Current requirements for the specified filter should be approximately the following:

- the filter should be quite effective in capturing this kind of dust;

- the filter should work at high peak concentrations (emissions) of dust;

- the filter must pick up odors (gaseous components of the heat treatment);

- the filter must be suitable for multiple regeneration;

- the filter must have a dust capacity that provides a sufficiently long period of time between regenerations.

The regeneration requirement for new filter designs is becoming ever more urgent. In the technique of air filtration, it is solved in different ways. In relation to these filters, this can be UV radiation, washing or heat treatment. Given the need for frequent regeneration, it is desirable that it (regeneration) does not cause significant difficulties either in the complexity of the process or in time.

Known filters used in filtration-photocatalytic air purifiers, installed in cabinets, offices and bedrooms (US patent 6330947, B01D 39/00). Such filters provide for continuous regeneration. However, photocatalytic filters are less effective in cleaning highly contaminated air (for example, from large dust particles). These filters are designed for small peak loads and concentrations of harmful substances (not more than 100 μg / m ³ ). For kitchen air purifiers, they are not suitable.

A cooker hood differs from conventional forced ventilation systems in that it deals with highly heated and highly polluted air. When working with such an aggressive environment, the ventilation device must be protected from overheating and vapors of boiling oil and grease.

Many manufacturers install grease filters made of acrylic fabric in these hoods. These filters are disposable, it is recommended to replace them with new ones, purchased separately, every one and a half to two months. According to experts, washing filters, practiced by some housewives, is useless, since it does not return the filters to their original qualities and deforms the filter itself. The filter does not remove odors.

Carbon cassette filters are known that are used in air purifiers to remove grease particles, soot, soot during cooking (electric household air purifier BEV-2601-3, Operation manual 2601.00.0.000.RE, UE Hephaestus-Technique, 2004). They work in a circulating mode (purified air returns to the kitchen). Activated carbon significantly reduces cooking odors. The aerosol cleaning efficiency of the air passing through the filter is approximately 85%. However, the carbon filter cannot be regenerated and must be replaced approximately every 3-6 months. Activated carbon is susceptible to oxidation over time. In this regard, gradually (after six months) there is a deterioration in its performance characteristics. For the same reason, it eventually becomes fire hazard. Carbon filters are used to purify air from household gas pollution and unpleasant odors, as a rule, in addition to other types of filters.

A known filter element for ventilation pipes (German application 102007016542, IPC F24C 15/20, 2006; Ukrainian patent 66489, B01D 45/12, 2004) made of several layers of metal. It is designed to remove smoke, child, droplets of fat. Periodic cleaning (regeneration) of such a filter from fat is easy to organize, for example, washing or calcining. However, the total surface in contact with filtered air is relatively small and therefore the efficiency of air purification with such a filter is not high enough (no more than 85%), especially with large single dust emissions (more than 700 μg / m ³ ) and relatively powerful exhaust. The filter does not remove odors.

A well-known honeycomb metal-ceramic filter for treating exhaust gases of internal combustion engines (EPO 1508357, B01D 39/20, 2000; US patent 6843817, B01D 39/20, 2001; US patent 7112234, B01D 39/20, 2004) or a honeycomb filter for treating exhaust gases ( EPO 1645319, B01D 39/20, 2004). These filters hold well the high temperature (up to 900 ° C) necessary for their thermal regeneration, but their dust absorption is limited, they clog relatively quickly, and their regeneration is laborious due to the difficulty of access of the oxidizing agent (air oxygen) to the filter pores. From the point of view of regeneration, fiber filters are more convenient. The filter does not remove odors.

A known filter containing basalt fibers (40-50%) for filtering exhaust gases (EPO 1862208, B01D 39/16, 2006). The filter is in the form of a felt-like substance and further includes fibers of polyimide, polyvinyl sulfide and polytetrafluoroethylene. Due to the presence of organic components in the filter, thermal regeneration (more than 400 ° C) does not withstand such a filter. The filter does not remove odors.

Typically, two types of filters are used in the hood at the same time: grease and charcoal. As a prototype of the invention, the filter proposed in US patent 7041147, B01D 35/30, 2005 was selected. The filter includes an inlet pipe for polluted air, an outlet pipe for purified air and a cartridge with filtering elements: a fibrous HEPA filter in the frontal layer and a carbon filter in the closing layer. Obviously, in general, the filter cannot be classified as recoverable, since the carbon filter cannot be regenerated. The patent does not contain information on the chemical composition of the fibrous material, which is absolutely necessary for the conclusion on the heat resistance of the material. As a rule, the HEPA filter material is also not sufficiently heat-resistant for its thermal regeneration and is fire hazardous. In general, the disadvantages of the filter include other disadvantages of the carbon filter, namely the short life and potential fire hazard.

The objectives of the invention are:

- the possibility of simplified (accessible to the user) periodic filter regeneration;

- increase the term (duration) of the filter;

- ensuring fire safety of the filter.

The above tasks of air purification are solved with the help of a dust and gas particle and aerosol filter, which contains an inlet pipe for contaminated air, an outlet pipe for purified air and a cartridge with filter elements, and differs in that mullite-siliceous cardboard is located in the front layer of the filter cartridge, and in the closing the layer is a hydrophobic zeolite.

The invention is expressed in the totality of the listed features. By removing any of these listed signs, it becomes impossible to achieve the specified technical result.

Mullite-siliceous cardboard is used as a heat-resistant fibrous filter material, which at the same time has sufficient efficiency to retain sticky dust. It withstands heating above 1100 ° C, and the efficiency of cleaning the aerosols (oil mist) of the air passing through the cardboard is approximately 96-98%. The chemical composition of cardboard (aluminum oxide (53%) and silicon oxide) does not contain organic components, so mullite-siliceous cardboard withstands a significantly larger number of thermal regeneration cycles than other known fibrous materials. The average fiber diameter is about 3 microns.

A mullite-siliceous fibrous filter assumes the main (frontal) impact of a liquid aerosol (oil) in the air stream and retains up to 90-98% of the total aerosol. The combination of cardboard fibers (diameter 3 μm) and grain (diameter 1 mm) of a hydrophobic zeolite in a single unit in the adopted sequence gives a certain synergistic effect in relation to the amount of filtered dust.

However, the hydrophobic zeolite in the proposed aerosol filter works not only as an additional aerosol filter (sticky oil film covers it completely), but also as an adsorbent of light hydrocarbons that give odors. The appearance of a smell at the outlet of the filter, thus, serves as an indicator of the exhaustion of the entire filter. Hydrophobic zeolite is quite effective in absorbing odors and is quite durable in use. For comparison, such a zeolite filter completely purifies the air in the room in half an hour, a carbon filter in an hour; if the carbon filter is to be replaced every six months, the proposed zeolite filter remains in working condition up to 4-5 years. It can withstand heating up to 600 ° C without destroying the porous structure. In the experiments, hydrophobic zeolite was used in the form of spheres with a diameter of about 1 mm.

The average operating time of the filter as a whole is approximately 4 years due to its possible regeneration, which is almost an order of magnitude longer than the operating time of the carbon filter.

Thus, the filter as a whole allows for easy thermal regeneration with its various variations (for example, with simultaneous air purging). The filter does not require regeneration in parts. The use of warm regeneration of such a filter should be recognized as a natural and convenient form, especially considering the very thermal nature of the origin of sticky dust. In practice, in everyday life, thermal regeneration is quite simple and short-lived. Both components of the filter are completely fireproof.

In principle, we allow the recovery process (photocatalytic regeneration) of the filter under the action of ultraviolet radiation on titanium dioxide contained in the fibers and zeolite. However, in practice this process is not quick, requires special installation and, as a rule, is difficult in the presence of dust in the filter volume.

The presence of these two components in the filter is essential. The exclusion or replacement of any of these components deprives the filter dust and gas trap of its advantages (it does not allow solving the above tasks).

It should be noted that since the development of the zeolite part of the filter, as a rule, always outstrips the time the development of the frontal part of the filter (the amplification of odors is fixed), the time of working out the filter as a whole is determined relatively simply.

It is important to always keep the order of the filter parts in relation to the air flow both during air purification and during its thermal regeneration. Mullite-siliceous cardboard is used in the frontal layer of the filter, and hydrophobic zeolite is used in the closing layer. This is due to the fact that the frontal layer of the filter always perceives the main load both in terms of dust (more than 99%) during the filtration process and in temperature during the regeneration process.

The invention is illustrated in the drawing (figure 1), which shows a General view of the filter. The filter contains an inlet pipe 1 for inputting contaminated air and an outlet pipe 2 for outputting purified air. Between the nozzles is a cartridge 3 with filter elements. Metal mesh 4 made of stainless steel serves to separate and fasten the frontal part of the filter 5 and the trailing part 6. The side part of the filter is also made of stainless steel.

When the filter is operating, the air intake is generated by a fan located behind the outlet pipe 2 (not shown in FIG. 1). The polluted air stream through the pipe 1 enters the frontal part of the filter 5 (mullite-siliceous cardboard), is cleaned of sticky organic dust and aerosols, and then passes the closing part of the filter 6 (hydrophobic zeolite), where up to 90% of all gas impurities that provide odors are absorbed. To prevent mixing of components and free passage of air, grids 4 were used. Cassette 3 and nozzles 1 and 2 during filter regeneration can be disconnected.

Example 1. The filter dust and gas trap is made in the form of a cartridge with a diameter of 150 mm and a height of 30 mm. The thickness of the fibrous mullite-siliceous cardboard (frontal part of the filter) is 10 mm. The density of the cardboard is 0,084 kg / m ³ . The thickness of the granular layer (grain diameter 1 mm) of the hydrophobic zeolite (the trailing part of the filter) is 20 mm. The packing density of the grain is 0.95 kg / m ³ . Air with oil mist (turbine oil Тп-22С) with an initial concentration of 2.5-5.0 g / m ^{3 was} blown through the filter. The linear velocity of the air flow was approximately 0.2 l / min · cm ² . The concentration of oil mist at the outlet of the filter is not more than 7 mg / m ³ . The dust absorption efficiency (oil mist) is more than 96%. The end of filter working out was determined subjectively (by the appearance of an oil smell). In addition, the end of mining was recorded by the increase in hydraulic resistance to gas flow. The amount of oil deposited on the filter is 3-5 g (by weight). The filter was regenerated by heating it on a household gas stove with the output of volatile decomposition components into the external environment for 30 minutes. The possibility of multiple filter regeneration is established.

Example 2. The filter dust and gas trap is made in the form of a cartridge with a diameter of 180 mm and a height of 35 mm. The thickness of the fibrous mullite-siliceous cardboard is 5-6 mm. The density of the cardboard is 0.16 kg / m ³ . The thickness of the granular layer (grain diameter 1 mm) of a hydrophobic zeolite is 30 mm. The packing density of the grain is 0.95 kg / m ³ . Air with oil mist (turbine oil Тп-22С) with an initial concentration of 2.5-5.0 g / m ^{3 was} blown through the filter. The linear velocity of the air flow was approximately 0.15 l / min · cm ² . The concentration of oil mist at the outlet of the filter is not more than 3 mg / m ³ . The dust absorption efficiency (oil mist) is over 98%. The end of filter working out was determined subjectively (by the appearance of an oil smell). The amount of oil deposited on the filter is 5-6 g (by weight). The filter was regenerated by heating it on a household gas stove with the output of volatile decomposition components into the external environment for 30 minutes. The possibility of multiple filter regeneration is established.

An important advantage of the filter is its simplicity and reliability. The filter performance has been repeatedly tested in parts and verified as a whole.

Claims (1)

A dust and gas separator for particles and aerosols, including an inlet pipe for polluted air, an outlet pipe for purified air and a cartridge with filter elements, characterized in that mullite-siliceous cardboard is located in the front layer of the filter cartridge, and a hydrophobic zeolite is located in the closing layer.