opening 

Industrial and domestic air purification. Industrial air purification Industrial air purification products

ULT AG - the best air filtration systems today!

Air filtration systems are designed to purify oxygen in places where it is polluted. For example, the functioning of many enterprises is associated with the formation harmful impurities. To neutralize their harmful influence, you need to use special devices. One of the best manufacturers filtration equipment is ULT AG.

Brand history

This company appeared quite recently - in 1994. Despite its short history, ULT AG has managed to prove that it is able to consistently provide the consumer with high quality products that meet the most stringent standards.

The success of the company is largely due to the global interest in the environment not only from environmentalists, but also from experts, the public and politicians. Cleaning devices turned out to be unusually in demand, because without them not a single enterprise would function. This set of circumstances has helped ULT AG become one of the most influential companies in the field.

Characteristic features of filtration systems

The most important feature is versatility. It is difficult to name an area in which these technical devices would not be appropriate. That is why the company's products are in high demand around the world.

Another important quality is manufacturability. The developments of ULT AG are so significant that they are used by other companies producing cleaning systems. Our own laboratory research allows you to always be one step ahead.

Industrial air filtration must be economical. Just imagine what kind of capacity any enterprise has. In order to avoid unnecessary operating costs, you should immediately take care that the equipment does not consume too much energy. This is exactly what ULT AG offers its customers.

In addition, filtration systems produced under this brand do not pose any danger to humans during operation. This criterion is extremely important, because emergency situations often occur in production. The use of high-quality technical devices helps to reduce the likelihood of such incidents. All ULT AG products meet these requirements.

Among the characteristic properties, it is necessary to note a special approach to the cleaning process itself. Filtration is carried out in such a way that harmful substances do not have time to spread. They settle almost immediately after the appearance.

High quality of work is provided by the modular systems capable to neutralize any pollution. To illustrate this fact, let's say that the degree of purification approaches 100%. Such a result can pleasantly surprise not only the average consumer, but also a specialist in this field.

The lineup

ULT AG offers its customers filtration equipment in a wide range. All equipment can be divided into a number of categories, each of which has many varieties. Implemented devices are designed for air purification:

  • when cutting, pouring or sintering;
  • in the process of gluing;
  • during lamination;
  • in the processing of metals;
  • during painting work;
  • in the process of welding / soldering;
  • when casting;
  • during laser processing or marking.

Among such a variety, it is easy to choose exactly what you need. All products are covered by a warranty. In addition, you can consult in detail on any issue related to the acquisition and operation of ULT AG.

Industrial air purification systems are aimed at removing particulate matter from emissions and gas inclusions. The latter suggest the course of chemical reactions that neutralize harmful impurities. Industrial filters for air purification are most often multi-stage. Each stage is performed by specialized equipment with specific characteristics and operating parameters.

Industrial air purification

Industrial air purification consists of two technological processes(systems):

  1. Coarse air cleaning system. At this stage, coarse solid pulverized impurities are removed.
  2. Fine cleaning system. Particles of medium and fine dispersion are captured, as well as the neutralization of harmful gaseous chemical elements and compounds. A separate category of equipment makes it possible to extract and dispose of oily and cementing substances.

At each stage, the gas flow is directed to special filters operating on fundamentally different technologies. As the first stage, a centrifugal inertial air purification filter is used.

Scope of application

Gas cleaning complexes are required in various production lines:

  • metallurgy;
  • gas production and gas treatment;
  • oil production and oil refining;
  • chemical and coke industry;
  • the food production industry;
  • light industry;
  • metalworking shops;
  • agricultural procurement complexes;
  • cement plants;
  • plants for the production building materials and mixtures;
  • mining;
  • wood and stone processing;
  • coal mining, etc.

In any production where there are industrial emissions and employees are at risk of getting sick with silicosis of the lungs, filtration equipment should be included in the production line.

Coarse air filter

Unlike a hydrofilter, a cyclone is a mechanical air purification device in which gas is supplied tangentially and spun in the form of a vortex funnel. Devices operating without liquid are not suitable for industries where contaminants are substances prone to self-ignition. For explosive connections, this category of devices is also not suitable. Mechanical systems Air purifiers work by centrifugal forces that throw heavy solid dust particles against the filter walls and into the dust collector.

Classification of coarse dust filters

There are two types of equipment for catching coarse dust:

  • installations for dry cleaning of atmospheric air at enterprises;
  • industrial wet cleaning systems.

The wet type industrial air cleaner is characterized by the use of a liquid as a trapping agent. Industrial water is more often used in air purification filter units. It is this factor that allows you to capture and neutralize impurities from the categories of explosive and flammable.

In the working cavity of the air purification unit, the walls of the tank of the air purification system are sprayed with water. Wetting is carried out continuously and abundantly. Water is taken from the tank, and after the end of the aspiration cycle, it is returned to the tank for reuse.

The adhering dust flows down with water, turning into sludge. However, cleaning the air in a room where people work involves capturing fine dust. For this, the complex includes a fine filter.

Air purification device

A device for air purification from medium and fine dust is a scrubber. This is the setting cylindrical shape where capture takes place. It is a standalone unit. This device is of the wet type.

As a trapping liquid - water or a reagent (for industries requiring the extraction of harmful gases). The scheme of the filtration complex along the path of the air flow looks like this:

  1. Pre-filter for catching large dusty inclusions of dry or wet type.
  2. A flow-through hydraulic filter for air purification from small and medium-sized solid impurities.

Air purification units are included in the complex sequentially. The complex may consist of a single installation, if its characteristics fully meet the requirements for filtration.

Types of scrubbers

The industrial scheme of the air purification system includes a scrubber of one of three types:

  • Ordinary hollow scrubbers for cleaning air in factories without a nozzle.
  • Industrial plants with fixed nozzle.
  • Highly efficient air filters with movable nozzle.

This division into classes allows you to choose best option in terms of price and efficiency. A qualitative indicator of the operation of filtration equipment is the degree of air purification. Modern technologies allow you to achieve 96-99.9%.

Selection and justification of the aspiration system

The presented types of filters for air purification differ in price and performance parameters. Both factors are individual, and are formed based on the requirements production line described in terms of reference. Which system is needed in a particular case is indicated in the design documentation and technical passport for the air purification plant at the enterprise.

The use of wet type equipment implies the possibility of moistening the gas. The choice of air purification and humidification system is determined by the requirements of production. Designers and designers begin to create the complex after reading the terms of reference, which indicates:

  1. The required performance of the system for cleaning the air of the working area from dust.
  2. Qualitative composition, which must be handled by air purification equipment in the enterprise.
  3. Fractional list of dust that the water filter should catch.
  4. The concentration of each of the impurity fractions neutralized by the air cleaner.

Depending on these indicators, a filter device is being developed.

Cleaning equipment products

Aspiration is the main, but not the only task solved using wet-type installations. In addition, you can:

  • humidify the processed gas;
  • clean the smoke of boiler rooms from soot, ash, carbon monoxide;
  • absorb chemical compounds;
  • redirect heat for further heating;
  • generate electricity.

Heating installations and power plants involve the supply of gas at high temperatures. Modern technologies are adapted to work with gases +700 0 C.

Absorption of chemical releases

Gas recovery systems are always wet type. The difference between dust filters lies in the cleaning liquid and the method of neutralization. In scrubbers for gas cleaning of chemicals, instead of technical water, reagents are used. They are an aqueous solution of compounds that react with impurities to neutralize the latter.

Each production requires its own set of reagents, which depends on the qualitative composition of the contaminants. The reaction products are also an aqueous solution. It contains compounds obtained as a result of chemical reactions. The choice of reagent is based on two criteria:

  1. capture efficiency.
  2. The possibility of using the resulting products.

So, when natural gas and oil are purified from hydrogen sulfide, hydrocarbonates and other substances are obtained that can be used as raw materials in the process of further processing.

Chemical Absorption Systems

The equipment for this purpose is a scrubber. The downward flow of finely dispersed reagent envelops the nozzle (stationary or mobile). The reversed gas passes through the sections and zones of the reagent mist. When interacting, a reaction occurs, the result of which is the absorption of pollutants by an aqueous solution.

The latter flows into the pan and is sent to the tank for reuse. The processed gas passes through a control unit (gas analyzer) before being released into the atmosphere. The task of the node is to establish the concentration of the remaining harmful impurities. If it is higher than the established norm, then re-capturing is required, and the gas is sent to the next cycle. If all requirements are met, it is released into the atmosphere.

Industrial air purification

Air purification on industrial enterprises produced by a complex that includes equipment with different efficiency indicators in the apparatus. Modern absorption technologies involve the use of the following types of filters:

  • dry type centrifugal filters;
  • devices for air purification in wet type production;
  • installations for cleaning air emissions from fine dust;
  • air purification systems in industrial premises from gaseous components (such production equipment is called an absorber and uses aqueous solutions of reagents as a liquid);
  • complexes, including various combinations of the listed devices.

The absorption process must ensure the safety of the health of workers and environment. Therefore, all types of industrial filters in workshops must have high efficiency. In addition, installations must comply with current health and safety regulations. To do this, in the manufacture of aspiration systems, materials are used that are resistant to corrosion processes and aggressive environments.

In this article, we will briefly review the methods of air purification that are used in industry, classify and give a brief description of them.

History of global pollution

Throughout its industrial history, mankind has polluted the environment in one way or another. Moreover, one should not think that pollution is an invention of the 19th and 20th centuries. So already in the 13-14th century, the Chinese silver casters of Khan Khubilai burned an enormous amount of firewood, thereby polluting the earth with combustion products. Moreover, according to archaeologists, the pollution rate was 3-4 times higher than in modern China, which, as you know, does not put the environmental friendliness of production in the first place.

However, after the industrial revolution with the advent of industrial zoning, the development of heavy industry, the growth in the consumption of petroleum products, pollution of nature, and in particular the atmosphere, became global.

Dynamics of carbon emissions into the atmosphere

(source wikipedia.org)

By the end of the 20th century, at least in developed countries, there was an awareness of the need to clean the air, and an understanding that the well-being of not only individual countries, but also of a person as a species depends on ecology.

A global movement began for the legislative limitation of atmospheric emissions, which was eventually enshrined in the Kyoto Protocol (adopted in 1997), which obligated signatory countries to quota harmful emissions in atmosphere.

In addition to legislation, technology is also improving - now thanks to modern devices for air purification, up to 96-99% of harmful substances can be captured.

Legislative justification for the use of air purification systems in industrial enterprises

The main document regulating environmental issues in the Russian Federation is Federal Law No. 7 “On Environmental Protection”. It is he who defines the concept of the rule of nature management, contains the norms for the use of the environment.

The types and penalties for violators of environmental law are contained in the Civil and Labor Codes of the Russian Federation.

In case of air pollution, the following penalties are provided for violators:

    Fines are set for the emission of harmful substances into the atmosphere: for entrepreneurs from 30 to 50 thousand rubles, for legal entities- from 180 to 250 thousand rubles.

    For violation of the conditions of a special permit for the emission of harmful substances, a fine is set for legal entities from 80 to 100 thousand rubles.

Areas of application for air purification systems

Means for purifying the air in one form or another are in every industrial production. But they are especially relevant for:

    Metallurgical enterprises that emit into the atmosphere:

    • ferrous metallurgy - solid particles (soot), sulfur oxides, carbon monoxide, manganese, phosphorus, mercury vapours, lead, phenol, ammonia, benzene, etc.

      non-ferrous metallurgy - solid particles, sulfur oxides, carbon monoxide, other toxic substances.

    Mining and processing plants that pollute the atmosphere with soot, nitrogen, sulfur and carbon oxides, formaldehydes;

    Oil refineries - in the process of operation, hydrogen sulfide, oxides of sulfur, nitrogen and carbon are emitted into the atmosphere;

    Chemical industries that emit highly toxic waste - sulfur and nitrogen oxides, chlorine, ammonia, fluorine compounds, nitrous gases, etc.;

    Energy enterprises (thermal and nuclear power plants) - solid particles, oxides of carbon, sulfur and nitrogen.

Tasks performed by air cleaning systems

The main tasks of any air purification system at the enterprise are reduced to:

    Capturing particles - residues of combustion products, dust, aerosol particles, etc. for their subsequent disposal.

    Screening of foreign impurities - steam, gases, radioactive components.

    Capturing valuable particles - screening out from the bulk of particles, the preservation of which has an economic justification, for example, oxides of valuable metals.

Classification of the main methods of air purification

It should be noted right away that there is no universal method, therefore, enterprises often use multi-stage air purification methods, when several methods are used to achieve the best effect.

Types of air purification can be classified as according to the way they work:

    Chemical methods for cleaning polluted air (catalytic and sorption cleaning methods)

    Mechanical air cleaning methods (centrifugal cleaning, water cleaning, wet cleaning)

    Physical and chemical methods of air purification (condensation, filtration, precipitation)

So for the type of pollution:

    Devices for air purification from dust pollution

    Devices for cleaning from gas pollution

Now let's look at the methods themselves.

The main methods of air purification from suspended particles

Sedimentation - foreign particles are screened out from the bulk of the gas due to the action of a certain force:

  • Forces of gravity in dust settling chambers.

    • Inertial forces in cyclone devices, inertial dust collectors in mechanical dry dust collectors.

  • Electrostatic forces that are used in electrostatic precipitators.

Examples of dust collection chambers

(Source: intuit.ru)

Filtration- foreign particles are filtered out with the help of special filters that pass the bulk of the air, but retain suspended particles. Main types of filters:

    Sleeve filters - in the case of such filters there are sleeves made of fabric (most often Orlon, bike or fiberglass fabric is used), through which a stream of polluted air passes from the lower pipe. Dirt settles on the fabric, and fresh air comes out of the nozzle at the top of the filter. As a preventive measure, the sleeves are periodically shaken, the dirt from the sleeves falls into a special sump.

    Ceramic filters - in such devices filter elements made of porous ceramics are used.

    Oil filters - such filters are a set of individual cassette cells. Inside each cell are nozzles that are lubricated with a special high-viscosity grease. Passing through such a filter, dirt particles stick to the nozzles.

Bag filter example

(Source: ngpedia.ru)

    Electrical filters - in such devices, the gas flow passes through electric field, fine particles receive an electric charge, after which they settle on grounded collecting electrodes.

Example of an electric filter

(Source: sibac.info)

Wet cleaning - foreign particles in the gas stream are deposited with the help of water dust or foam - the water envelops the dust with the help of gravity flows into the sump.

Most often, scrubbers are used for wet gas cleaning - in these devices, the stream of polluted gas passes through a stream of fine water droplets, they envelop dust under the action of gravity, settle and drain into a special sump in the form of sludge.

There are about ten types of scrubbers, differing in design and principle of operation, it is worth highlighting separately:

1. Venturi scrubbers - have a characteristic hourglass shape. The operation of such scrubbers is based on the Bernoulli equation - an increase in the speed and turbulence of the gas due to a decrease in the flow area. At the point of maximum velocity, in the central part of the scrubber, the gas stream is mixed with water.

Venturi scrubber

(source: en.wikipedia.org)

2. Atomizing hollow scrubbers - the design of such a scrubber is a hollow cylindrical container, inside of which there are nozzles for spraying water. Water droplets capture dust particles and flow down into the sump under the action of gravity.

Scheme of a nozzle hollow scrubber

(Source: studopedia.ru)

3. Foam-bubbling scrubbers - inside such scrubbers there are special bubbling nozzles in the form of a lattice or plate with answers, on which there is a liquid. The gas flow, passing through the liquid at high speed (more than 2 m/s), forms foam, which successfully cleans the gas flow from foreign particles.

Foam bubbling scrubbers

(source: ecologylib.ru)

4. Packed scrubbers, they are also a tower with a nozzle - inside such scrubbers there are various nozzles (Berl saddles, Raschig rings, rings with partitions, Berl saddles, etc.), which increase the contact area between polluted air and the cleaning liquid. Inside the housing there are also nozzles for spraying the contaminated gas stream.

Packed scrubber example


For the neutralization of aerosols (dusts and mists), dry, wet and electrical methods are used. In addition, the devices differ from each other both in design and in the principle of sedimentation of suspended particles. The operation of dry apparatuses is based on gravitational, inertial and centrifugal mechanisms of sedimentation or filtration mechanisms. In wet dust collectors, dusty gases come into contact with a liquid. In this case, deposition occurs on drops, on the surface of gas bubbles or on a liquid film. In electrostatic precipitators, the separation of charged aerosol particles occurs on the collecting electrodes.

The choice of method and apparatus for capturing aerosols primarily depends on their disperse composition. one

Table 1. Dependence of the apparatus for trapping on particle size

Particle size, µm Apparatus Particle size, µm Apparatus
40 – 1000 Dust collection chambers 20 – 100 scrubbers
20 – 1000 Cyclones with a diameter of 1–2 m 0,9 – 100 Fabric filters
5 – 1000 Cyclones with a diameter of 1 m 0,05 – 100 Fiber filters
0,01 – 10 Electrostatic precipitators

Dry mechanical dust collectors include devices that use various deposition mechanisms: gravitational, inertial and centrifugal.

Inertial dust collectors. With a sharp change in the direction of the gas flow, dust particles under the influence of inertial force will tend to move in the same direction and, after turning the gas flow, fall into the bunker. The effectiveness of these devices is small. (Fig. 1)

Venetian blinds. These devices have a louvered grille consisting of rows of plates or rings. The purified gas, passing through the grate, makes sharp turns. Due to inertia, dust particles tend to maintain their original direction, which leads to the separation of large particles from the gas flow, the same is facilitated by their impact on the inclined planes of the grating, from which they are reflected and bounce away from the slots between the shutter blades. As a result, gases are divided into two streams. The dust is mainly contained in the stream, which is sucked off and sent to the cyclone, where it is cleaned of dust and again merged with the main part of the stream that has passed through the grate. The velocity of the gas in front of the louver must be high enough to achieve the effect of inertial separation of dust. (Fig. 2)

Typically, louvered dust collectors are used to capture dust with a particle size of >20 µm.

The efficiency of particle collection depends on the efficiency of the grate and the efficiency of the cyclone, as well as on the proportion of gas drawn off in it.

Cyclones. Cyclone devices are the most common in industry.

Rice. 1 Inertial dust collectors: a- with a partition; b - with a smooth turn of the gas flow; in - expanding cone.

Rice. 2 Louvre dust collector (1 - frame; 2 - lattice)

According to the method of supplying gases to the apparatus, they are divided into cyclones with spiral, tangential and helical, as well as axial supply. (Fig. 3) Cyclones with axial gas supply operate both with the return of gases to upper part apparatus, and without it.

The gas rotates inside the cyclone, moving from top to bottom and then moving up. Dust particles are thrown by centrifugal force towards the wall. Usually, in cyclones, the centrifugal acceleration is several hundred or even a thousand times greater than the acceleration of gravity, so even very small dust particles are not able to follow the gas, but move towards the wall under the influence of centrifugal force. (Fig. 4)

In industry, cyclones are divided into high-efficiency and high-performance.

At high flow rates of the gases to be purified, a group arrangement of apparatuses is used. This allows not to increase the diameter of the cyclone, which has a positive effect on the cleaning efficiency. The dusty gas enters through a common collector and then is distributed between the cyclones.

Battery cyclones- Union a large number small cyclones in a group. Reducing the diameter of the cyclone element aims to increase the cleaning efficiency.

Vortex dust collectors. The difference between vortex dust collectors and cyclones is the presence of an auxiliary swirling gas flow.

In the nozzle-type apparatus, the dusty gas flow is swirled by a vane swirler and moves upward, being exposed to three jets of secondary gas flowing from tangentially located nozzles. Under the action of centrifugal forces, the particles are thrown to the periphery, and from there into the spiral secondary gas flow excited by the jets, directing them down into the annular annular space. The secondary gas in the course of a spiral flow around the stream of purified gas gradually completely penetrates into it. The annular space around the inlet pipe is equipped with a retaining washer, which ensures the irreversible descent of dust into the hopper. Vane-type vortex dust collector is characterized by the fact that the secondary gas is taken from the periphery of the purified gas and supplied by an annular guide vane with inclined blades. (Fig. 5)

Rice. 3 Main types of cyclones (for gas supply): a- spiral; b– tangential; in-helical; d, d– axial

Rice. 4. Cyclone: ​​1 - inlet pipe; 2 - exhaust pipe; 3 - cylindrical chamber; 4 - conical chamber; 5 - dust settling chamber

As a secondary gas in vortex dust collectors, fresh atmospheric air, part of the purified gas or dusty gases can be used. The most economically advantageous is the use of dusty gases as a secondary gas.

As with cyclones, the efficiency of vortex devices decreases with increasing diameter. There may be battery installations consisting of separate multi-elements with a diameter of 40 mm.

Dynamic dust collectors. Cleaning of gases from dust is carried out due to centrifugal forces and Coriolis forces arising from the rotation of the impeller of the draft device.

The most widely used smoke exhauster-dust collector. It is designed to capture dust particles >15 µm in size. Due to the pressure difference created by the impeller, the dusty flow enters the "snail" and acquires a curvilinear motion. Dust particles are thrown to the periphery under the action of centrifugal forces and, together with 8–10% of the gas, are discharged into a cyclone connected to the snail. The purified gas flow from the cyclone returns to the central part of the cochlea. Purified gases through the guide apparatus enter the impeller of the smoke exhauster-dust collector, and then through the casing of emissions into the chimney.

Filters. The operation of all filters is based on the process of gas filtration through a partition, during which solid particles are retained, and the gas passes completely through it.

Depending on the purpose and the value of the input and output concentrations, filters are conditionally divided into three classes: fine filters, air filters and industrial filters.

Bag filters are a metal cabinet divided by vertical partitions into sections, each of which contains a group of filtering sleeves. The upper ends of the sleeves are plugged and suspended from a frame connected to a shaking mechanism. At the bottom there is a dust hopper with an auger for unloading it. The shaking of the sleeves in each of the sections is performed alternately. (pic 6)

Fiber filters. The filter element of these filters consists of one or more layers in which fibers are uniformly distributed. These are volumetric filters, since they are designed to trap and accumulate particles mainly throughout the entire depth of the layer. A continuous layer of dust is formed only on the surface of the densest materials. Such filters are used at a concentration of the dispersed solid phase of 0.5–5 mg/m 3 and only some coarse fiber filters are used at a concentration of 5–50 mg/m 3 . At such concentrations, the main fraction of particles is less than 5–10 μm in size.

There are the following types of industrial fiber filters:

- dry - fine-fibre, electrostatic, deep, pre-filters (pre-filters);

- wet - net, self-cleaning, with periodic or continuous irrigation.

The filtration process in fibrous filters consists of two stages. At the first stage, the trapped particles practically do not change the structure of the filter over time; at the second stage of the process, continuous structural changes occur in the filter due to the accumulation of trapped particles in significant quantities.

Grainy filters. They are used for gas purification less often than fibrous filters. Distinguish between packed and rigid granular filters.

Hollow scrubbers. Hollow jet scrubbers are the most common. They represent a column of circular or rectangular cross section, in which contact is made between gas and liquid droplets. According to the direction of movement of gas and liquid, hollow scrubbers are divided into counter-flow, direct-flow and transverse liquid supply. (Fig. 7)

Packed scrubbers are columns with bulk or regular packing. They are used to capture well-wetted dust, but at a low concentration.

Rice. 5 Vortex dust collectors: a- nozzle type: b - blade type; 1 - camera; 2 - outlet pipe; 3 - nozzles; 4 - bladed swirler of the "socket" type; 5 - inlet pipe; 6 - retaining washer; 7 - dust bunker; 8 - annular blade swirler

Rice. 6 Bag filter: 1 – housing; 2 - shaking device; 3 - sleeve; 4 - distribution grid

Gas scrubbers with movable nozzle are widely used in dust collection. Balls made of polymeric materials, glass or porous rubber are used as nozzles. The nozzle can be rings, saddles, etc. The density of the nozzle balls should not exceed the density of the liquid. (Fig. 8)

Scrubbers with a movable conical ball nozzle (KSH). To ensure the stability of operation in a wide range of gas velocities, improve the distribution of liquid and reduce the entrainment of splashes, apparatuses with a movable ball nozzle of a conical shape are proposed. Two types of devices have been developed: injector and ejection

In an ejection scrubber, the balls are irrigated with liquid, which is sucked from a vessel with a constant level of gases to be cleaned.

Disc scrubbers(bubbling, foam). The most common froth machines are with dip trays or overflow trays. Plates with overflow have holes with a diameter of 3–8 mm. Dust is captured by the foam layer, which is formed by the interaction of gas and liquid.

The efficiency of the dust collection process depends on the size of the interfacial surface.

Foam machine with foam stabilizer. A stabilizer is installed on the failure grid, which is a honeycomb grid of vertically arranged plates that separate the cross section of the apparatus and the foam layer into small cells. Thanks to the stabilizer, there is a significant accumulation of liquid on the plate, an increase in the height of the foam compared to a failed plate without a stabilizer. The use of a stabilizer can significantly reduce water consumption for irrigation of the apparatus.

Gas scrubbers of shock-inertial action. In these devices, the contact of gases with a liquid is carried out due to the impact of a gas flow on the surface of the liquid, followed by passing the gas-liquid suspension through holes of various configurations or by direct removal of the gas-liquid suspension to the liquid phase separator. As a result of this interaction, droplets with a diameter of 300–400 µm are formed.

Rice. 7 Scrubbers: a– hollow nozzle: b- packed with transverse irrigation: 1 - body; 2– nozzles; 7 - body; 2– nozzle; 3 - irrigation device; 4 - support grid; 5 - nozzle; 6 – sludge collector


Rice. 8. Gas scrubbers with a movable nozzle: a - with a cylindrical layer: 1 - support grid; 2 - ball nozzle; 3 - restrictive lattice; 4 - irrigation device; 5 - spray trap; b and in - with a conical layer nozzle and ejection: 1 - housing; 2 - support grid; 3 - layer of balls; 4– spray trap; 5 - restrictive lattice; 6 - nozzle; 7 - container with a constant liquid level

Centrifugal gas scrubbers. The most common are centrifugal scrubbers, which can be divided into two types according to their design: 1) devices in which the gas flow is swirled using a central blade swirler; 2) devices with lateral tangential or volute gas supply.

High-speed scrubbers (Venturi scrubbers). The main part of the devices is a spray pipe, which provides intensive crushing of the irrigated liquid by a gas flow moving at a speed of 40–150 m/s. There is also a drop catcher.

Electrostatic precipitators. Purification of gas from dust in electrostatic precipitators occurs under the action of electrical forces. In the process of ionization of gas molecules by an electric discharge, the particles contained in them are charged. Ions are absorbed on the surface of dust particles, and then, under the influence of an electric field, they move and are deposited to the collecting electrodes.

The following methods are used to neutralize exhaust gases from gaseous and vaporous toxic substances: absorption (physical and chemisorption), adsorption, catalytic, thermal, condensation and compression.

Absorption methods for cleaning exhaust gases are divided according to the following criteria: 1) by the absorbed component; 2) according to the type of absorbent used; 3) by the nature of the process - with and without gas circulation; 4) on the use of the absorbent - with regeneration and its return to the cycle (cyclic) and without regeneration (non-cyclic); 5) on the use of captured components - with and without recovery; 6) by type of recovered product; 7) on the organization of the process - periodic and continuous; 8) on the design types of absorption equipment.

For physical absorption, water, organic solvents that do not react with the extracted gas, and aqueous solutions of these substances are used in practice. In chemisorption, aqueous solutions of salts and alkalis, organic substances, and aqueous suspensions of various substances are used as an absorbent.

The choice of purification method depends on many factors: the concentration of the extracted component in the exhaust gases, the volume and temperature of the gas, the content of impurities, the presence of chemisorbents, the possibility of using recovery products, the required degree of purification. The choice is made on the basis of the results of technical and economic calculations.

Adsorption gas purification methods are used to remove gaseous and vaporous impurities from them. The methods are based on the absorption of impurities by porous adsorbent bodies. Purification processes are carried out in batch or continuous adsorbers. The advantage of the methods is a high degree of purification, and the disadvantage is the impossibility of purification of dusty gases.

Catalytic purification methods are based on chemical transformations of toxic components into non-toxic ones on the surface of solid catalysts. Gases that do not contain dust and catalyst poisons are subjected to purification. Methods are used to purify gases from oxides of nitrogen, sulfur, carbon and organic impurities. They are carried out in reactors various designs. Thermal methods used to neutralize gases from easily oxidized toxic impurities.



An important element ventilation units are dust cleaners. Cleaning is carried out if the supply and exhaust air contains dust in quantities exceeding those allowed by the standards.

Cleaning can be: fine, medium and coarse.

Fine cleaning is used in supply systems to retain fine dust fractions (10 microns and below), as well as during recirculation, when the dust-free air is released back into the working room or partially mixed with the supply air in order to save heat.

With medium cleaning, dust particles with a size of 10-100 microns are captured. Dust-removing installations of exhaust ventilation are supplied with medium cleaning.

The purpose of coarse cleaning is to remove mainly dust particles larger than 100 microns from the exhaust air. It is used in cases where the dust transported by air consists mainly of large particles (sawdust, husks, etc.).

Sometimes two-stage purification of exhaust and especially recirculation air from dust is used: at the first stage; coarse dust is caught, on the second - fine.

The efficiency of air purification from dust is characterized mainly by weight (gravimetric) indicators and is expressed as a percentage according to the formula:

where d1 is the concentration of dust in the air before cleaning in milligrams per 1 m 3;
d2 - dust concentration after cleaning.

So, for example, at the initial dust content d1 = 100 mg/m 3 and the final d2=10 mg/m 3 the dust retention weight efficiency will be:

The choice of one or another dust-cleaning device is determined by the dispersion, physical and chemical properties of the dust, the required degree of purification, and technical and economic considerations. Considerations about the possibility of recycling the trapped dust are essential.

For fine cleaning, oil and paper filters are used, assembled in installations from individual cells.

The oil filter cell is a flat metal box with mesh bottoms. The box is filled with steel rings. The cells are wetted with a special grade, odorless liquid oil with a constant viscosity over a wide temperature range. The air, passing through the filter in a winding way, leaves dust on the surface of the filler, covered with an oil film. Periodically contaminated cells are washed with a hot soda solution, dried and oiled again. In addition to metal, porcelain rings, metal and plastic corrugated meshes, mineral fiber, etc. are used as cell fillers.

At in large numbers air to clean it from dust using self-cleaning oil filters, which are a mesh tape, continuously moving in a vertical direction. When the tape passes through the oil bath installed at the bottom of the filter, it is released from the trapped dust and the oil layer resumes on it.

Paper filters are used at high dispersion and low initial dust concentrations. Porous paper (silk, alignin) is laid in 8-10 layers on a corrugated mesh attached to a metal frame. Paper layers contaminated with dust are replaced with fresh ones. Roll paper filters are used.

If there is a need for very fine air purification (for example, from radioactive dust), special filter materials FPP and FPA are used, which practically ensure complete dust collection in the so-called LAIK filters.

Coarse and medium, and in some cases fine air purification from dust, used in exhaust ventilation installations, can be performed using various wet and dry methods.