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Abstract

Сontents

Introduction

Dust. What associations do people at a meeting with this word? Most say, they say dirt, unsanitary conditions and decide that you need to tidy up the apartment. If you ask a person more experienced in this matter, a person engaged in the development and maintenance of domestic ventilation systems, you can find another interesting property of the dust — it is dangerous. When you are exposed to is not the fact that you start inhaling from sneezing or coughing. Dust — cause more serious diseases allergies. It is on the dust particles move various harmful bacteria and viruses. The conclusion should be the same — need to get rid of dust.

And now let's look at the dust from a different angle — by the employee of an enterprise, but rather the person responsible for dedusting. Besides the above information, we learn another interesting thing: dust — valuable resource. Yes, in spite of its danger and harm, dust valuable. For example, take the jewelry industry. Precious stones, metals and minerals, before heading to the shelves are processed. Thus one of the main processes are grinding and polishing operations. It is those operations in which the chip is formed, ie dust. And what do we put a fan and will throw gold, platinum, diamonds, and other valuable resources into the atmosphere? Of course not, we will try to collect the dust and put to use again. Therefore, in such enterprises, we meet some of the most advanced air pollution control systems.

But here there is a value of dust. And what about the expense of industrial enterprises? The same — you need to pick up dust. Consider the common clay. clay — it is not dirt. Yes, unlike gold, couple grams of clay, trapped in the atmosphere will not cause losses to the enterprise. But when you consider that the construction industry enterprises in the manufacturing process produce tons of dust, the unprofitability of such emissions visible without calculations. Of course you would think that the dust from clay or coal is not dangerous. Unfortunately this is not true. All mineral dust inhaled in large quantities cause incurable lung disease — pneumoconiosis.

Now we can conclude — dust is a problem. And this problem is based on two seemingly unrelated aspects: the dangers and values ??of dust. Of course, for different types of dust ratio of these different concepts. So there is dust, which has extreme danger to human health and life, but not having any value for use. Although perhaps the potential of its use has not yet been disclosed. What today seems rubbish, tomorrow can be a major resource for existence. But mankind has begun to think about it only in the XIX century — it was then patented the first cyclone dust collector. It then began to develop techniques and technologies dedusting. The problem of dust and relevant today.

Not too bright prospects loom, is not it? But all is not so terrible. In fact, everything is solved by filtration of industrial emissions. And unless emissions are not filtered, you ask? Of course filters and various equipment for dust abatement costs in many companies, but that's the problem, it is worth. Lots of gas cleaning equipment already for several decades, and of course it is out of date both mentally and physically. It is about opportunities to improve and develop advanced pollution control equipment will be discussed.

1. Actuality

The Earth's atmosphere has the ability to self-cleaning and restoration of violations [1], caused by human activity. When a catastrophe accompanied emission occurs imbalance of natural processes. With the passage of time under the action of this mechanism, the balance is recovered, but stronger than the violation, the more time is needed for recovery. With constant exposure to industrial emissions atmosphere does not have time to recover, which entails irreversible changes, usually negative. Cleaning the air directly to the atmosphere is difficult to implement the process. All the emphasis in research and development is to reduce pollutants entering the atmosphere.

2. Effect of air pollutants on the environment and people

Human health is largely dependent on the quality of the air entering the body. At high air pollution in humans begins violation of health, and with prolonged exposure — development of chronic diseases.

Emissions from industrial pollution, energy systems, transport in the atmosphere has a direct impact on all living things. Suffering nature, plants and animals die, there is an increased incidence of the population. The effects of pollution on humans and animals is manifested primarily in the upper respiratory tract, as well as reducing the body's resistance to infectious agents. Adversely affect the health of humans and animals lead compounds emitted by road, leading to nervous disorders, anemia, memory loss, blindness and infertility.

High dustiness of air leads to pulmonary and allergic diseases, registered in 20% of the urban population. Hazardous pollutants formed during the production of cement and glass. Ambient air pollution poses a threat not only to human health, but also carries huge economic losses.

Picture 1 — Scheme sources of air pollution

Dusty atmosphere prevents the penetration of UV rays that help cleanse the air of harmful bacteria. Despite the harmful effects of ultraviolet radiation on all living organisms, reducing its level below the norm will lead to the spread of diseases, epidemics and pandemics possible.

3. Industrial pollution of the atmosphere by ultrafine particles

Activities of enterprises is not without emissions in the form of dust and toxic substances. The presence in emissions of large dust particles or droplets of chemicals at this stage though is dangerous, but in enterprises provide effective gas cleaning system [6] successfully coping with particles of dirt. Studies show that large particles represent a certain threat to the environment and human health. Such particles have a relatively large mass and size, which reduces their risk, since the great mass of the particle, even got into the air eventually settle, and, the heavier and larger the particle, the less time it is suspended.

Picture 2 — Methods of Abatement

Picture 3 — The principle of integrated dust collection system

The main sources of industrial emissions are power plants and heavy industry, which respectively account for almost two-thirds of man-made pollution. In the composition of gas and dust emissions are oxides of nitrogen and sulfur, ash, fine particles of fuel, dangerous radioactive elements, dioxins, carbon dioxide and many other harmful substances. Significant air pollutant is motor vehicles.

4. Aerosols, nano air pollutants in various spheres of human activity

Particularly dangerous particles of very small size, which when mixed with air or gas medium to form ultrafine system (UFS) — aerosols [2]. It affects the so–called size effect: the smaller the particle size, the greater its active surface. The greatest danger to man up and aerosol particles and nanometer–sized ultra– size range. Because of the very small size of these particles can penetrate through the pores of the light and even cell membranes, which leads to irreversible processes in the cells and the development of severe disease. Ultrafine particles are found not only in the enterprises, but also in terms of residential complexes: perfumes, air fresheners, powder, talc, makeup products and household products.

Modern civilization is increasingly a problem of artificial aerosols. Distribution of particulate matter in a gas passage of time is increasing. In the 60–70s of the twentieth century study of tiny particles were carried out only in specific industries such as the nuclear industry, electronics, aerospace. Currently ultrafine particle size can be found everywhere. This is due to increasing demands for accuracy and quality of products. It also stimulates the search for new, more high–tech ways to improve the manufacturing process.

However, without the ultrafine particles, in particular nanoparticles, our everyday life is unthinkable. Nanotechnology has a great potential for the use of research in the field of climate protection and natural resources. Studies using nanoscale particles can spend development of efficient technologies for environmental protection and methods for obtaining renewable energy. Pay attention to the inorganic nanoparticles, which are a valuable resource. As with any phenomenon, the problem of nanoparticles has two sides. On the one hand due to their specific properties, certain nanoparticles can be used in medicine. On the other hand, all insufficiently explored nanoparticles may carry greater risk .

5. Air domestic premises — special problem

In everyday life, the air recovery, especially with modern glazing and sealing in the apartments is very urgent. Air coming into the living room from the atmosphere, e.g, relatively clean air, which poses no threat to human health can be found except in mountainous areas or in remote villages with little road transport at long distances from any industrial complexes. In the cities, especially in metropolitan areas, the air contains different types of aerosol particles, bacteria and chemicals. Their number is small, but great exposure period, which adversely affects the health and well-being of people. The problem of purification of the feed air in a room is partially solved by using air conditioners having a function of a cleaner, but they provide cleaning of coarse dust and, at best, only partially from microorganisms.

Picture 4 — Photograph of the structure of household dust under a microscope

House dust may contain hair and pet dander, feather fragments, insect parts, human hair and skin, fungal spores, nylon, fiberglass, sand, particles and tissue paper, tiny fragments of materials from which made ??the walls, furniture and household items.

Therefore, it is necessary to clean the apartment and is in the air. Usually this does not attach importance to, but during the life of a man accustomed to using a variety of chemicals, cosmetics, air fresheners, powders , detergents and other MAC. It is known that odors are the result of contact with the molecules of substances on the olfactory receptors. Flavoring agents are also chemicals. When injected into the olfactory person feels pleasant or unpleasant smell, but eventually get used receptors and the sensitivity decreases. However, the flavor particles continue to fall into the respiratory system and that begin to accumulate. From an excess of these compounds in the human body can develop an allergy, the immune system and worsen the overall tone.

Also, the person himself is the source of aerosol particles: particles of skin, hairs up 80–85% of the human dust in the living room. Aerosol particles of organic origin can serve as the birthplace of pathogens. All this - recovery factors airspace in a residential area and cleaning the air entering from outside.

6. Known scale and partial solutions to ensure clean air

As an example, the treatment of large volumes of dust-laden gas from the dust can cause an industrial cleaning. All dust collection system installed at enterprises, designed for efficient use in large gas flows. To do this, apply various filters [3], separators, sprinklers, etc [4]. Cleaning of small volumes of gas are usually carried out with the help of filters. Such filtering devices peculiar portable type (equipment for air sampling) or to protect the rights (masks, respirators) [5]. These devices have a high degree of purification of air, but filters are single use. However, conventional industrial dust collectors do not carry cleaning air to the maximum permissible concentrations of ultrafine particles. For example, industry capture efficiency of particles below 1 micron never reaches 99%.

Picture 5 — Scheme of the main methods for the purification of industrial emissions

In this connection, will push the development of highly efficient filtration methods. The result of research and development in this area has been the emergence of so-called absolute filters. These filters allow you to capture ultrafine particle size range: radioactive particles, bacteria and germs and odors and mists. Further studies in this area have been developed cellulose and glass fiber filter materials. Capture particles in these environments do not occur mainly through mechanical sieving, as a result of deposition of particles on the fibers while passing the gas stream.

Cleaning efficiency in filtering taken is calculated by the following formula:

ψ — structure index of filter layer;

η'Σ — total capture coefficient.

Summary capture ratio indicates the number of trapping factors involved in passing the gas stream through the filter.

η'R — capture coefficient by touch;

η'Stk — capture coefficient due to inertia;

η'D — capture coefficient due to molecular diffusion;

η'G — capture coefficient due to gravitational forces;

η'E — capture coefficient due to electrostatic forces.

Conclusion

After analyzing this formula, we can conclude that the filtering process— one of the most complex processes in abatement. Moreover, while passing the gas stream through the filter particles are at least five different factors, depending on the particle size of those or other factors acting on the particle in a different extent.

Studying the properties of nanoparticles is possible by their capture or receipt. Particles in the gas and dust emission enterprises also need to study the physical properties. These particles are difficult to obtain in the laboratory, because of their heterogeneity and unpredictable properties. If we study the behavior of ultrafine particles in the gas stream for further possible to construct equipment for effective separation of these particles from the stream. Nanoparticles, there are specific studies examining the issue of allocation of particles from the gas stream.

Currently, there are many ways and solutions for gas purification from various fine impurities. During studies of ultrafine particles, their properties and behavior laws have been proposed many different innovative technical solutions and utility models. In analyzing the structure of the device, their applicability and effectiveness can see similarities in the structures and identify different ways to capture the MAC [7]. Analysis of these data allows us to classify the device for cleaning gas from aerosols on the mechanisms for cleaning up:

  1. Ozonation. To clean the air of odors, active chemicals and bacteria are widely used ozone generators — ozone generators. These devices use an electrical charge under the influence of oxygen in air is converted into ozone. Ozone is a very strong oxidizing agent, which reacts with the chemical components neutralizes them. Ozone also has useful antiseptic properties. Ozone generators are widely used in various fields of medicine, equipment for climate control, portable device to remove odors.
  2. Filtering . The solid fine particles and liquid droplets typically collected using a gas through a porous filter material at low speeds. Used in industry fibrous materials with different structures: granular, fibrous, bag and paper filters. Application filtering materials can achieve a very high filtration efficiency (about 99.9%). Such filters are called absolute. The main disadvantage of this method is the complexity of the gas purification, or not regeneration of the filter material. This leads to a sharp increase in the cost of such a filtration method.
  3. Chemical treatment. Separate kind of ultrafine particles that pose a threat to humans, are bacteria and viruses. When cleaning the air of these particles is to pay attention to what is necessary not just to capture and neutralize or destroy microorganisms in the air. For these purposes special widely different chemical compositions having antiseptic properties in the input gas stream. But while such formulations should not bear any harm to human body. Also antibacterial compounds are often used not by introducing them to the dispersed state in the gas, and by treating the surfaces in the room.
  4. Sorption. For cleaning of gas emissions and indoor air from chemically active components used sorbents. With this type of sorbent depends on the type of the captured substance. Filtration through a bed of sorbent is usually occurs through the granular layer.
  5. Air purification from suspended impurities. Carried out in an atmosphere of mist or by collision of the gas stream with a solid or liquid surface. The particles contained in the gas adsorb solid surface or wetted and coagulated, then perhaps their selection from a stream of simple dust or mist eliminators.
  6. Wet dedusting. Common wet scrubbers and rotary scrubbers are dust collectors, and the fluid used in baghouses can be with any impurities and additives which impart antiseptic or anti–static properties.
  7. Ultraviolet radiation. Air purification by harmful microorganisms as possible with UV radiation. To do this, use a variety of UV lamps that irradiate passing gas.

In modern engineering and technology have long ceased to use filtering using only one cleaning mechanism. To improve the cleaning efficiency of these factors combine in a single device. All of these ways to capture , disinfection and air recovery have their advantages and disadvantages. Some of them are applicable only to small volumes of gas and small velocities. However, there are objects which must be cleaned and decontaminated with large volumes of gas. Such systems are common and very little they paid little attention to the studies, but the need for effective cleaning of large volumes of gases increases. In the future we plan to continue to study the properties of dust and based on them to offer a technical solution that will handle a wide range of problems faced by dedusting device.

In the future it is possible to use more exotic and high-tech ways to capture. For example, based on ponderomortnogo light pressure, ie the pressure of light waves on solids. But while the main focus on improving the quality filtering yavletsya combination of different ways to capture in a single device. Not a new idea is presented in a vacuum, and purged yavlyaetsya processing of several ideas of others, or their combination.

References

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