RU2674967C1 - Method of purifying high-temperature aerosols - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to the purification of high-temperature aerosols from emissions of harmful substances (including solid particles and substances hazardous to the environment and humans) of industrial production. In the method of cleaning high-temperature aerosols from harmful substances in industrial emissions, carry out a multi-stage cleaning of high-temperature aerosols, at which produce at least one stage of purification of coarse aerosol from the dispersed phase with simultaneous controlled withdrawal of precipitated solid particles from the area of their separation, heat recuperation or recovery and coordinated single-stage or multi-stage reduction of the high temperature of the aerosol to the operating temperature for changing at the subsequent stages the chemical composition of the aerosol and the proportions of the content in the aerosol of its components in different state of aggregation and for the mechanical cleaning of the aerosols from the dispersed phase.EFFECT: invention is aimed at improving the efficiency of the method and the quality of cleaning aerosols by achieving a deep degree of purification due to the agreement between the stages of purification of temperature regimes, volume and size of solid particles between the stages, which leads to a decrease in the cost of cleaning, reduction of dispersed phases in the atmosphere and their collection, as well as the continuity of cleaning and creating the necessary conditions for the effective cleaning of the aerosol from harmful chemical compounds.13 cl, 23 dwg, 2 tbl

Description

The invention relates to the cleaning of high-temperature aerosols from harmful substances of industrial production, for example, in the petrochemical and oil refining industries, in particular, in the cleaning processes of high-temperature aerosols generated in catalytic processes, and can be used in any other technological processes in which it is necessary to clean from harmful substances and dispersed phases high-temperature aerosols.

Industrial enterprises emit a large amount of harmful substances into the atmosphere. Impurities of atmospheric air entering the environment with industrial emissions adversely affect the human body, plants, animals and biogeocenoses in general. Therefore, it is necessary to limit the entry of harmful substances into the biosphere. This problem is solved under production conditions by improving technological processes, introducing dust and gas cleaning systems, that is, devices that implement certain methods of cleaning from dispersed phases contained in aerosols.

Industrial waste gases containing suspended solid or liquid particles are two-phase systems. The continuous phase in these systems is gases, while the dispersed phase is solid particles or liquid droplets.

Such aerodispersion systems are called aerosols. Aerosols are divided into dust, fumes and mists. Dusts contain solid particles ranging in size from 5 to 50 microns, and fumes from 0.1 to 5 microns. Fogs consist of droplets of liquid with a size of 0.3-5 microns and are formed as a result of vapor condensation or by spraying a liquid in a gas.

Aerosols, the dispersed phase of which consists of solid particles, if they do not precipitate, speak of smoke (free-dispersed aerosols) or dust (coarse-dispersed aerosol).

The sizes of particles in aerosols vary from fractions of micrometers to several millimeters.

The most significant difficulties arise when it is necessary to remove solid particles of high-temperature aerosols consisting of at least free-dispersed and coarse-dispersed aerosols that are simultaneously released into the atmosphere.

These difficulties are due to the fact that:

• Aerosol is hot.

• An aerosol consists of a mixture of free-dispersed and coarse-dispersed aerosols (that is, they have a substantially heterogeneous composition in terms of the size of the solid particles contained in the gaseous medium (air)).

• High consumption of the amount of aerosol per unit time. Various variants of this method differ in the use of specific forces, under the action of which the deposition of solid particles is carried out.

It is known that they use:

• Gravity forces

• Inertia forces

• Coriolis Force

• Centrifugal forces

• Electrostatic forces

• Mechanical containment forces

The separation of two-phase systems is usually associated with an increase (or regulation) of the relative velocity of the phases and can be carried out in one of three main ways or in combination:

- an increase in the relative velocity of phases in conservative fields (for example, potential) - gravity (sedimentation) and centrifugal fields (centrifugation, deposition in cyclones and direct-flow centrifugal separators) are most often used;

- reducing the speed of the dispersed phase to zero while maintaining the speed of the continuous phase (filtering);

- separation during particle collision, irrigation or absorption, while the velocity of the particles of the dispersed phase is reduced to the velocity of the coarsened particles, which are less difficult to isolate.

Devices that use only one of the separation mechanisms (dust collectors, rotary dust separators, cyclones, nozzle, foam and hollow scrubbers) are mainly used to capture relatively large particles. To collect fine dust (or ash), electrostatic, fabric, fiber and paper filters, as well as high-speed washers are usually used.

The deposition process is the removal of dust and other particles from the gas from the gas. Dust collection coefficient η is a measure of the quality of particle removal from a gas. This parameter is defined as a decrease in the concentration of particles in the gas and the initial concentration of these particles.

Degree of capture:

η = [(с0-с1) / с0] -100%

Dedusting

C ₀ → Dust collector → C ₁ , where

С ₀ - concentration before dust removal;

C ₁ - concentration after dedusting.

The smaller the size of the dust, the worse the process of its deposition. Therefore, during the deposition of coarse dust, dust collection has higher coefficients. At the same time, for fine dust these indicators are always lower.

The range of cleaning aerosols from the solid particles (dust) contained in it (the so-called dedusting range) does not depend on the cleaning method, but is determined by the design features of devices that implement methods for cleaning aerosols from the solid particles contained in them.

The cleaning range for various devices that implement a mechanical method for cleaning aerosols from solid particles (dust) contained in it

Assume that the solids in the aerosol have a size of from 0.01 μm to 1000 μm. In this case, a multi-stage cleaning of such an aerosol can be carried out by a sequence of devices: Cyclone with a diameter of 1-2 m (reduces the largest fraction to 20 microns in the output) - Fiber filter (reduces the largest fraction to 0.05 microns in the output) - Electrofilter (reduces at the output, the largest fraction is up to 0.01 μm).

Each previous stage cleans the inlet aerosol of solid particles in such a way that the aerosol at the exit is admissible in size of the largest fraction for the implementation of the next stage.

Particles of industrial dust contained in aerosols have various shapes (balls, sticks, plates, needles, flakes, fibers, etc.). Dust particles can coagulate and combine into agglomerates, so the concept of particle size is arbitrary. When cleaning aerosols from the solid particles contained in it, it is customary to characterize the particle size by a value that determines its deposition rate. This value is the so-called sedimentation diameter - the diameter of the ball, the deposition rate and density of which are equal to the deposition rate and particle density. In this case, the particle itself can have an arbitrary shape. Dust particles of various shapes with the same mass settle at different speeds. The closer their shape is to spherical, the faster they settle.

The largest and smallest particle sizes characterize the dispersion range of a given dust. To characterize the dispersed composition of dust, the entire mass of dust particles is divided into some fractions limited by particles of a certain size, indicating what percentage of the mass (or number of particles) they comprise.

The dispersed composition of dust is shown in the form of integral curves. Most industrial dust obeys the normal logarithmic law of particle size distribution.

With the wide dispersion of solid particles contained in the aerosol, the technical implementation of the one-stage method for the mechanical cleaning of aerosols becomes either difficult, or unreasonably expensive, or even impossible.

In such conditions, use the method of multi-stage cleaning of aerosols from the solid particles contained in it. The purification steps are carried out sequentially. Each stage is implemented by its technical device.

In multi-stage cleaning, the sequence of stages and devices implementing each stage is fundamental. As a rule, first they are purified from larger fractions, and then fine fractions.

Consider the method of cleaning coarse aerosols, consisting in the deposition of solid particles under the influence of gravity (gravitational deposition), which is based on the following:

Solid particles that are in the gas are affected by forces such as buoyancy force F _A and gravity F _G. And in the process of settling of a particle, a flow resistance force also arises, which is denoted as F _W. When the resulting force Fr is formed, equilibrium arises between these three forces. The resulting force has a downward direction of action and causes the dust to settle at a speed of V _A , gravitational deposition is reflected in FIG. 1: acting forces - 1; dust particles - 2; particle settling rate - V _A.

The particle velocity of particle deposition is directly proportional to their size. In addition, particles whose size is less than 0.1 μm do not precipitate at all due to the fact that in such particles the thermal motion prevails over gravity.

In the event that it is necessary to use gravity to precipitate particles, that is, an aerosol supply mode should be chosen so that the particles have sufficient time for deposition. This process is achieved in a gas treatment channel. The gas channel is a fairly large tank into which an aerosol is directed.

At this moment, the flow velocity decreases, and the cross section of the flow, on the contrary, increases, because the gas is in the gas duct for a certain time.

In this case, some of the particles are lowered into the dust collector, from which dust is removed as it accumulates. Those particles that did not leave the flow path and descend do not precipitate at all.

In FIG. 2 shows gravitational deposition in a gas channel, where a guide plate is indicated under 3.

Particle sizes that are susceptible to precipitation are called separation size. The lower the flow velocity and the higher the flow path, the smaller the separation size.

In the dust collection pocket, you can see the lowest flow paths. In the pocket, the cross section of the flow is separated using horizontal chord nozzles.

Thus, the sedimentation rate of dust particles is very small. Particles fall onto chord attachments and form large flakes. And thanks to the vibrator, the flakes are lowered along inclined surfaces into a cylindrical collector (see Fig. 3 with the accepted position designations: 4 — travel nozzles; 5 — gas movement in the chamber; 6 — dust collector; 7 — vibrator).

Note that gravitational deposition in a gas channel is only suitable for removing dust particles about 100 microns in size. And to remove fine dust, a carrier gas stream is used.

Other mechanical methods for cleaning aerosols, consisting in the deposition of solid particles under the action of other forces, work similarly.

These methods are implemented by the so-called dry dust collectors, which are divided into types depending on the force used, under the influence of which particles are deposited:

• gravitational;

• inertial;

• centrifugal;

The mechanical method of separating solid particles from aerosols (primarily coarse aerosols), which consists in the fact that the mechanical separation of solid particles from aerosols is carried out by the deposition of solid particles under the action of centrifugal forces, the so-called centrifugal dust collectors are implemented. In various modifications of this method and devices that implement it, it uses additional actions that increase the efficiency of separation of solid particles from aerosols. In particular:

• irrigate with liquid (water)

• twist into vortices

• use the action of other forces

• create use Coriolis force

A device that implements a method of cleaning aerosols by mechanically extracting solid particles from an aerosol based on the action of centrifugal force is the so-called centrifugal dust collector - the most common type of mechanical dust collector, which is used in food, chemical, mining and many other industries.

The main advantage of such dust collectors is their low cost, high performance, prostate mechanism, and also quite simple and not expensive operation.

When comparing centrifugal dust collectors with other types, they have such advantages as reliable operation at high temperature and pressure, the absence of parts that move, ease of repair and manufacturing, and the ability to use abrasive particles contained in aerosols to trap.

The most popular centrifugal dust collectors are wet-film cyclones. In such apparatuses, particle deposition occurs by the action of centrifugal forces and inertial forces.

Therefore, the efficiency of such devices is much higher than that of cyclones, because due to the presence of a wet film there is no secondary entrainment of solid particles. In addition, such devices are more efficient than scrubbers due to the fact that the speed of the droplets and gas flow in them is much higher due to centrifugal force.

In wet cyclones, liquid irrigation is used.

In wet cyclones, liquid is supplied along the internal walls of the apparatus and into its axial zone.

The most effective wet dust collector is a Venturi scrubber (see Fig. 4), which refers to high-speed devices: 8 - housing; 9 - confuser; 10 - diffuser; 11 - switchgear; 12 - tangential entrance; 13 - mixer; 14 - sump. Such settings can be divided by area of use into:

• Low pressure, used for concentration and purification of aerosol (aspiration air). The hydraulic resistance of such devices is in the range from 3000 to 500 Pa.

• High-pressure apparatuses are used to clean aerosols from submicron and micron dust. Their resistance reaches 20000-30000 Pa.

The work of such devices is based on the movement of aerosol at high speed (high-velocity gas stream), which performs intensive crushing of the liquid that irrigates it. And due to the turbulence of the gas stream, as well as a sufficiently large difference between the speed of liquid droplets and particles, dust particles are deposited on the liquid droplets that irrigate it.

In order to reduce hydraulic resistance, the main part of the scrubber is made in the form of a Venturi pipe, which gradually narrows at the inlet of the aerosol stream and expands at their exit. The inlet and outlet of aerosol streams are connected using a nozzle.

For stable operation of the apparatus, it is very important that there is a complete and uniform irrigation of the cross section of the neck of the liquid. That is why the choice of irrigation method is very important and affects the design of the apparatus.

Most often, three ways of irrigation of the neck are used:

1. Peripheral. With this method of irrigation, nozzles or nozzles are mounted around the perimeter of the neck or confuser.

2. Central. Irrigating liquid enters the neck of the nozzles that are installed in the confuser or in front of it.

3. Film. It is used most often in order to prevent the formation of deposits on the walls.

Another device that implements a method of cleaning aerosols by mechanical separation of solid particles from an aerosol based on the action of centrifugal force is the so-called cyclones.

In cyclones, vortex swirling is used as additional action

Aerosol (contaminated gas), as a rule, at a speed of 20 to 25 m / s enters the cyclone body. The gas flow moves tangentially, resulting in a rotational motion. Dust particles recline by centrifugal force and fall into the extreme layers of contaminated gas, which move in a spiral downward along the walls of the cyclone.

Suspended solids contained in aerosols are discharged from the installation through a special outlet pipe. The aerosol rotates and rises, resulting in a vortex. This vortex moves in the direction of the installation axis toward the exhaust pipe and captures with it a part of the aerosol from the inner layers moving down. This aerosol layer is characterized by a low solids content. It moves along the conical part of the body to the lower edge of the exhaust pipe. Upon reaching the lower edge of the exhaust pipe, the flow unfolds towards the axis of the cyclone.

Increasingly, vortex dust collectors are used in industry (see Fig. 5 with the accepted designations of the positions: 8 - housing; 15 - cowling; 16 - snail inlet of the upper gas flow; 17 - axial-blade swirls; 18 - breaker washer; 19 - entrance of the lower gas flow). Such an apparatus resembles a cyclone, but its feature is the presence in it of an additional swirling gas flow. Various models of such dust collectors are produced in the world, having a productivity of 300-40000 m3 / hour. The productivity of vortex dust collectors increases with decreasing diameter.

In vortex dust collectors, atmospheric air, aerosols (dusty gases), and also the peripheral part of the clean gas stream are used as secondary gas.

If we compare vortex dust collectors with counterflow cyclones, the former have such advantages as working with high-temperature gases, a good degree of purification, and adjustment of the process of gas purification from dust by adjusting the flow rate of secondary air.

Among the disadvantages of vortex dust collectors, high hydraulic resistance, the need for a powerful draft device, as well as complex operation and installation, should be highlighted.

In such an apparatus, an aerosol (untreated gas stream) enters the apparatus through the nozzles, swirls, and then enters the working area of the vortex dust collector. Under the influence of centrifugal force, dust particles from the gas are directed to the walls of the apparatus. And under the influence of gravity they go down. After that, they fall into a special bunker. At the same time, the purified air is managed through the exhaust pipe.

Another type of device that implements the mechanical method of aerosol cleaning is the so-called dynamic dust collectors (see Fig. 6 with the accepted position designations: 20 dynamic dust collector; 21 - cyclone).

A feature of dynamic dust collectors is that in such devices the gas is cleaned from dust not only by centrifugal force, but also due to the Coriolis force that occurs during the rotation of the impeller. In such dust collectors, in addition to particle deposition, the function of a draft device is also performed.

This type of dust collector uses more electricity than a fan with the same pressure and performance. However, this energy consumption is still less than the required consumption when the centrifugal dust collector and fan are separately functioning.

The design of the simplest dynamic dust collectors consists of a casing and an impeller. The impeller drives an aerosol (raw gas). And under the influence of the Coriolis force and centrifugal force, dust particles are released from the aerosol.

Dynamic dust collectors are divided into two groups. The devices of the first group operate in such a way that a gas stream with dust is supplied to the central part of the wheel, and the dust particles that are separated during the cleaning process move in the direction of the aerosol supply. Dust collectors of the second group of dust particles move in the opposite direction to the movement of the aerosol. In this case, an aerosol (crude gas) is sucked into the holes of the drums, which are located on its side surface.

The most popular dynamic dust collectors are smoke exhausters. Such devices are used for the initial purification of gases for asphalt plants, linear production. Such dynamic dust collectors are capable of retaining dust particles whose size is not less than 15 microns. The impeller on the shaft creates a pressure difference, with the help of which the movement of gases is performed. And under the influence of centrifugal forces, dust particles are discarded in the periphery, and after that they are removed from the apparatus with a certain amount of gas.

The mechanical method of separating solid particles from aerosols (primarily coarse aerosols), which consists in the fact that the mechanical separation of solid particles from aerosols is carried out by the deposition of solid particles under the influence of gravitational and inertial forces realize the so-called dust precipitators.

The principle of operation of these devices is that the solid particles contained in the aerosol are removed from the aerosol under the action of inertial forces. In such installations, the aerosol sharply changes the direction of motion and at the same time loses its speed of movement, as a result of which suspended particles, trying to maintain their speed level, are released from the aerosol.

One of the types of these installations is a louvered ash collector. Structurally, such an apparatus is a pipe equipped with a lattice of inclined partitions. The function of the partitions is a kind of filtering of solid particles. So, suspended ash particles pass through the pipe with a gas stream and hit the partitions. Such contact of the particles with the surface of the gratings casts them in the opposite direction of the motion of the general gas flow.

Thus, an aerosol with a high solids content in it (about 10% of the total flow) is accumulated on one side of the grate, and an aerosol with a low solids content in it (purified aerosol) on the other side.

Typically, the aerosol is discharged into ash collectors and then subjected to further purification in cyclones. This is the so-called sequential aerosol cleaning.

Gravity and inertial dust collectors allow you to clean the gas flows from large and heavy particles, the minimum size of which is 50 microns. Such plants are used only for preliminary cleaning of aerosols, including those having a high concentration of solid particles (dust).

The simplest in design is a dust (precipitation) chamber. The deposition of solid particles in the chamber occurs when the aerosol (dusty gas) flow is slow.

Dust chambers are large and low efficiency. Nevertheless, they are widely used in such industries as chemical, mining and metallurgical. The advantages of these devices are that they are simple and reliable in operation, have low hydraulic resistance.

In FIG. 7 shows a dust chamber. Given the enormous size of the chamber, most often brick or concrete is used for its manufacture. Particle deposition occurs during laminar motion of the air flow, the speed of which should be up to 1-2 m / s. At a higher speed, secondary entrainment of particles is possible.

The efficiency of the dust chamber increases with an increase in its area and a decrease in height. Therefore, for greater performance, the camera is equipped with horizontal or inclined shelves at a distance of 100-300 mm from each other vertically. Thus, when installing n shelves, the efficiency of the dust chamber increases n times.

A multi-shelf precipitation chamber with horizontal shelves (precipitation shelves 22) is shown in FIG. 8, and a multi-shelf settling chamber with inclined shelves 23 is shown in FIG. 9.

In dust chambers, the deposition of solid particles from aerosols is possible not only from horizontal flows, but also vertical ones.

To work with a vertically moving aerosol, reflex type devices (or reflectors) are used. Their main component is an annular collector mounted on a chimney in which particles are deposited.

To increase the cleaning efficiency in a dust chamber and reduce its size, gravitational deposition is combined with inertial one.

In particular, they design such a structure in which the direction of movement of the aerosol sharply changes. In this case, inertial forces begin to act on solid particles in the aerosol, causing them to strive to move in the same direction. As a result, solid particles are easily separated from the gas stream (released from the aerosol). According to this principle, many inertial dust collectors work. An example is the design of “dust bags” that are typical in this class.

To reduce secondary ablation, the inertial dust collector design provides a deeper hopper and a cylindrical part of the housing.

The mechanical method of separating solid particles from aerosols (primarily coarse dispersed aerosols), which consists in the fact that the mechanical separation of solid particles from aerosols is carried out by deposition of solid particles under the influence of gravitational so-called dust precipitation chambers (Fig. 10 with the accepted position designations: 24 - chamber; 25 - internal partitions).

The principle of operation of the dust precipitation chamber is that inside the unit the gas moves so slowly that the polluting particles have time to settle as a result of the action of gravity. The lower the height of the chamber, the faster the particles settle.

For this reason, horizontal partitions (parallel or inclined) are installed inside such chambers. The distance between the partitions is in the range from 400 to 1000 mm. Thus, the deposition surface increases, and the gas is distributed more evenly across the width of the chamber. This type of apparatus is characterized by low efficiency and large dimensions.

Such installations are used only for primary rough cleaning of gases.

The camera has the following device. The case is equipped with horizontal shelves. The shelves are located at a distance of 100-300 mm from each other and form channels. Entering the chamber body, dusty gas passes between the shelves, and solid particles are deposited on their surface. A vertical reflective partition is also installed in the casing, which ensures uniform distribution of gas through the channels. After the gas passes the shelves, it goes around this partition and is removed from the chamber. When the gas goes around the partition, part of the dust is removed from it under the influence of inertia. The removal of the solid phase from the chamber is carried out through the hatches using scrapers or washed off with water.

Dust collecting chambers allow you to install a large number of shelves, thereby increasing the surface area for dust deposition. However, despite this, they are able to make gas cleaner by no more than 30-40%. Only large particles larger than 5 microns are deposited. For this reason, dust precipitation chambers are used for rough cleaning of coarse aerosols (highly dusty gases) in which there are relatively large solid particles.

A variation of the inertial installation is a louver dust collector. Its design provides a lattice of inclined plates, which changes the direction of gas flow. The louvred dust collector allows you to select particles larger than 20 microns and is used in cases where preliminary gas treatment is necessary. After which the gas undergoes further purification in cyclones or bag filters.

Another type of device that implements a mechanical method of aerosol cleaning is the so-called louvered ash collectors (see Fig. 11 with the accepted position designations: 21 - cyclone; 26 - inclined partitions).

In a conical type inertial dust collector (FIG. 12) with a filter grate 27, the aerosol moves from top to bottom through the grate. The lattice is represented by a set of overlapping rings that are located at a distance of 2-3 mm. Dust and part of the original aerosol (dusty air) are thrown to the axis of the dust collector. The cleaned aerosol passes through the grate and is removed from the casing. Dusty air escapes through the narrow lower opening of the apparatus.

The advantages of inertial dust collectors are usually small dimensions and simplicity of design (including the absence of moving parts).

Consider also the so-called Rotary dust collectors.

Mechanical rotating dust collectors (rotary) are installations that simultaneously move and clean the air. A typical scheme of a rotary dust collector is shown in FIG. 13, having the following position designations: 28 - ring receiver; 29 - the impeller; 30 - dust collector; 31 - hopper for collecting dust.

The rotating wheel is made in the form of a concave disk on which the blades are placed. This design is placed in a cochlea-shaped case. Contaminated gas is supplied through a pipe along the axis of the wheel. As a result of inertial forces, gas fills the space in the narrow channels between the blades of the wheel. Solid dust particles, having a greater weight than gas, are subject to centrifugal forces. Dust is pressed against the disk and the blades, slides along them from the center to the periphery and enters the space between the casing and the disk. After which the particles are removed to the dust collector. From the dust collector, a gas mixture containing up to 5% of gas enters the hopper, where it settles. Pure gas is discharged through the outlet pipe.

The advantages of these plants are usually attributed to: high performance, small dimensions, ease of operation, high-quality cleaning of fine dust particles.

Now consider porous filters

Porous filters implement a method of mechanical cleaning of aerosols in which solid particles are mechanically separated from aerosols in several successive stages by deposition of solid particles under the action of inertial and electrostatic forces

The work of all types of porous filters is based on the process of aerosol filtration through a porous septum, during which solid particles are retained and gas passes completely through it.

Filtering partitions are very diverse in their structure, but they mainly consist of fibrous or granular elements and are conditionally divided into the following types:

• flexible porous partitions - fabric materials from natural, synthetic or mineral fibers; non-woven fibrous materials (felts, glued and needle-punched materials, paper, cardboard, fibrous mats); cellular sheets (sponge rubber, polyurethane foam, membrane filters);

• semi-rigid porous materials - layers of fibers, shavings, knitted nets located on thrust devices or sandwiched between them;

• rigid porous partitions - granular materials (porous ceramics or plastic, sintered or pressed metal powders, porous glass, carbon-graphite materials, etc.); fibrous materials (formed layers of glass and metal fibers); metal mesh and perforated sheets.

In the process of aerosol cleaning, particles approach the fibers or the surface of the grains of the material, collide with them and precipitate mainly as a result of inertia and electrostatic attraction. Passing through the filtering baffle, the flow is divided into thin continuously disconnecting and closing trickles. Particles, possessing inertia, tend to move in a straight line, collide with fibers, grains and are held by them.

Such a mechanism is characteristic for the capture of large particles and manifests itself more strongly with increasing filtration rate. The electrostatic mechanism of dust capture is manifested when the fibers carry charges or are polarized by an external electric field.

In the filters, trapped particles accumulate in the pores or form a dust layer on the surface of the septum, and thus become a part of the filtering medium for newly arriving dust particles. As dust accumulates, the porosity of the septum decreases, and the resistance increases.

Therefore, there is a need for dust removal and filter regeneration.

Depending on the purpose and magnitude of the input and output concentration, the filters are conventionally divided into three classes:

• fine filters (high-performance or absolute filters) - are designed to capture with very high efficiency (> 99%) mainly submicron particles from industrial gases with a low input concentration (<1 mg / m3) and a filtering speed <10 cm / s. Filters are used to capture particularly toxic particles, as well as for ultra-fine air purification during certain technological processes that prevent the presence of dust. Fine filters are not regenerated;

• air filters - used in systems of forced ventilation and air conditioning. They work at a dust concentration of less than 50 mg / m3, with a high filtration rate - up to 2.5-3.0 m / s. Filters can be non-regenerable and regenerable;

• industrial filters (fabric, granular, coarse fiber) are used to purify industrial gases with a dust concentration of up to 60 g / m3.

Filters are regenerated.

Let's dwell on fabric filters.

Fabric filters are the most common. The possibilities of their use are expanding in connection with the creation of new heat-resistant and resistant to aggressive gases tissues.

Bag filters are most common.

The filter housing is a metal cabinet divided by vertical partitions into sections, each of which contains a group of filter bags. The upper ends of the sleeves are muffled and suspended from a frame connected to a shaking mechanism. At the bottom there is a dust bin with a screw for unloading. Shaking the sleeves in each of the sections is performed alternately.

Two types of filtering materials are used in fabric filters: ordinary fabrics made on looms and felts obtained by lapping or mechanical entangling of fibers using the needle-punched method. In typical filter tissues, the size of the through pores between the threads reaches 100-200 microns.

The following requirements are imposed on fabrics:

• high dust capacity during filtration and the ability to hold after regeneration such an amount of dust that is sufficient to ensure high efficiency of gas purification from fine particulate matter;

• preservation of optimally high air permeability in an equilibrium dusty state;

• high mechanical strength and resistance to abrasion during repeated bending, dimensional stability and properties at elevated temperatures and aggressive exposure to chemical impurities in dry and saturated with moisture gases;

• ability to easily remove accumulated dust;

• low cost.

Existing fabrics do not have all of these properties and are selected depending on the specific cleaning conditions. For example, cotton fabrics have good filtering properties and have a low cost, but have insufficient chemical and thermal resistance, high combustibility and moisture capacity.

Woolen fabrics are characterized by high breathability, provide reliable cleaning and regeneration, but resistance to acid gases, especially to SO ₂ and fog of sulfuric acid, is low. Their cost is higher than cotton. With prolonged exposure to high temperature, the fibers become brittle. Work at a temperature of gases to 90 ° C.

Synthetic materials displace materials from cotton and wool due to higher strength, resistance to high temperatures and aggressive influences, lower cost. Among them are nitron fabrics, which are used at a temperature of 120-130 ° C in the chemical industry and non-ferrous metallurgy. Lavsan fabrics are used to clean hot dry gases in the cement, metallurgical and chemical industries.

In acidic environments, their resistance is high, in alkaline environments it decreases sharply.

Glass fabric racks at 150-350 ° C. They are made from aluminoborosilicate alkali-free or magnesian glass.

The aerodynamic properties of clean filter fabrics are characterized by breathability - air flow at a certain pressure drop. The resistance of non-dusted fabrics at loads of 0.3-2.0 m3 / (m2⋅min) is usually 5-40 Pa. With dusting, the aerodynamic drag of the fabric increases, and the gas flow through the filter decreases.

The fabric is regenerated by blowing in the opposite direction, mechanical shaking or other methods.

After several cycles of filtration-regeneration, the residual amount of dust in the fabric stabilizes; it corresponds to the so-called equilibrium dust content of the fabric and the residual resistance of the equilibrium dusty fabric. The values of these values depend on the type of filter material, the size and properties of dust particles, the relative humidity of the gases, the regeneration method and other factors.

The most widely used are the so-called bag filters.

Bag filters are used for the complete deposition of fine dust. The degree of purification of dusty air with bag filters is 98 ... 99.6% - The aerodynamic resistance of the filters is in the range of 0.6 ... 1.2 kPa. Bag filters with impulse purge of the FRKI type are effective. These devices have a low specific consumption of compressed air for cleaning the hoses during their purging, reliable in operation and convenient for maintenance.

The bag filter (Fig. 14) consists of a metal housing 32 provided with an inlet 33 and an outlet, inspection hatches 36, a dust collecting bin 31 and covers 37, filter bags 38, a chamber 24, a compressed air pipe 43, a diffuser 10, and a device for pulsed purging of hoses during their cleaning from a layer of dust.

The sleeves are equipped with rigid frames, are closed at the bottom and connected to diffusers at the top 10. The device for pulsed purging of the sleeves includes air distribution pipes 40 with nozzles 39, valve sections 41 with membrane solenoid valves 42, and an electric pulse programmer controlling the valves 42.

Bag filter works as follows. Aerosol (dusty air) through the nozzle 33 enters the chamber 24 under the influence of the vacuum created by the fan. Having passed the filter bags 38, the aerosol is cleaned of dust and through the holes (diffusers 10) in the upper part of the bags enters the chamber 24. The purified aerosol (purified air) is removed from the bag filter through the outlet pipe 34 and is discharged into the atmosphere by the fan.

As dust accumulates on the surface of the sleeves, the aerodynamic drag of the filter increases. Cleaning (regeneration) of the sleeves from dust is carried out without turning off the apparatus separately for each row of sleeves and lasts for 0.2 ... 0.3 s by applying a pulse of compressed air through the nozzle 39 to the diffuser part of each sleeve. Entering the sleeve through the diffuser 10, a stream of air draws in (injects) purified air from the chamber 24 and creates increased pressure in the sleeve. In this case, the sleeve inflates, destroying the dust layer, which is separated from the fabric by the reverse pulse air flow and is poured into the hopper 31. Dust is periodically unloaded from the hopper through the lock gate by a screw conveyor.

The supply of pulses of compressed air is carried out by briefly opening the membrane solenoid valve 42, separating the pipe 43 with the air under pressure 0.3 ... 0.4 MPa, and the air distribution tubes 40. The valve 42 opens upon receipt of electrical pulses from the programmer. The programmer is equipped with knobs, with which you can change both the duration of the pulses and the time between pulses. This allows you to select the desired regeneration mode of the filter bags, depending on the properties of dust and tin used filter material.

Technical characteristics of the bag filter type FRKI - 60: number of sleeves 72 pcs .; sleeve sizes: diameter 135 mm, length 2 m; filter surface 60 m2; maximum air temperature 130 ° C; maximum dust content of air 50 g / m3; compressed air consumption per 1000 m3 of dusty air 1 ... 2 m3. As the material of the sleeves, lavsan, felt, etc. are used.

Multi-stage cleaning is implemented, as a rule, as a sequence of devices, each of which performs a single-stage cleaning of aerosols from the solid particles (dust) contained in it. For example, in FIG. 15 shows multi-stage cleaning in the production of phosphoric flour (cascade dust cleaning), where

44 - oven; 45 - dust precipitation chamber; 46 - electrostatic precipitator; 47 - smoke exhaust; 48 - foam apparatus.

The cleaning steps are performed sequentially. In this case, the stages may be agreed upon or not agreed upon.

For example, the agreed stages will be when each previous stage cleans the inlet aerosol of solid particles so that the outlet aerosol is admissible in size of the largest fraction for the implementation of the next stage.

Multi-stage cleaning of aerosols from the solid particles (dust) contained in it can be implemented as a series of devices, each of which performs a single-stage cleaning of aerosols from the solid particles (dust) contained in it, and one technical device.

In FIG. 16 shows a dust collector-classifier and is indicated by:

53 - I, II, III - three stages of gas purification; 8 - case; 33 - inlet pipe; 49 - pipe branch of a large fraction of dust; 50 - inclined bottom; 51 - pipe outlet of the middle fraction of dust; 52 - receiving cylinder of the second stage of gas purification; 54 - screen; 55 - receiving cylinder of the third stage of gas purification; 56 - motionless blades; 34 - output pipe; 57 - conical bottom; 58 - branch pipe removal of fine dust

In the dust collector-classifier, gas is cleaned at several stages, in which deposition is carried out due to inertia and centrifugal force.

This device is intended for use when it is necessary to solve several problems: to efficiently separate dust from an aerosol, and also to classify it by fractions, since particles of a certain size are the target product.

Let us dwell on electrostatic precipitators.

Electrofilters are efficient devices designed to clean aerosols from dust particles.

Electrofilters are widely used in almost all industries: thermal power, ferrous and non-ferrous metallurgy, chemical and petrochemical industries, in the construction industry, in the production of fertilizers and the disposal of household waste.

The essence of the mechanical cleaning process, in which the deposition of solid particles (dust) is carried out on the basis of electrostatic forces, is as follows.

An aerosol containing solid particles passes through a system consisting of grounded precipitation electrodes and corona electrodes placed at some distance (called the interelectrode gap), to which a high-voltage direct current is applied. At a sufficiently high voltage applied to the interelectrode gap at the surface of the corona electrode, intense shock ionization of the gas occurs, accompanied by the appearance of a corona discharge (corona), which does not propagate throughout the interelectrode gap and attenuates as the electric field decreases in the direction of the precipitation electrode.

In FIG. 17 shows the charging and deposition mechanism in the electrostatic precipitator and is indicated: 59 - corona electrode; 60 - electrons; 61 - ions; 62 - solid particles (dust particles); 63 - precipitation electrode;

Gas ions of different polarity, formed in the corona zone under the action of electric field forces, move to opposite electrodes, as a result of which an electric current arises in the interelectrode gap, called the corona current.

Due to adsorption of ions on their surface, the trapped particles acquire an electric charge in the interelectrode gap and, under the influence of electric field forces, move to the electrodes, deposited on them.

The main amount of particles is deposited on the developed surface of the precipitation electrodes, a smaller part of them falls on the corona electrodes. As they accumulate on the electrodes, the deposited particles are removed by shaking or washing the electrodes.

In FIG. 18, 19 reflect the electrostatic precipitator, where under the positions indicated:

64 - rectifier; 65 - distribution grid; 66 - filter power supply system.

The main pollutants, the content of which in the atmosphere is regulated by air quality standards, are sulfur dioxide SO ₂ , nitrogen oxides NO and NO ₂ , carbon monoxide CO and gaseous hydrocarbons HC and particulate matter [1]. Among other pollutants emitted into the atmosphere, the content of sulfur trioxide SO ₃ , reduced sulfur compounds (hydrogen sulfide H ₂ S and carbon disulfide CS ₂ ), ammonia NH ₃ , benzene C ₆ H _{6 is} usually controlled.

Nitrogen oxides. The environmental hazard of NO ₂ is several times greater than NO. It is a reddish-brown gas with a suffocating and pungent, annoying odor, it dissolves well in water, forming a reddish-brown liquid, which hardens at -10.2 ° C and forms colorless crystals. Nitrogen dioxide adversely affects people's health, affects the respiratory system, lungs. Even temporary inhalation of air with a concentration of nitrogen dioxide of 200-500 mg / m ³ may turn out to be extremely life-threatening. A greater danger to living organisms is the formation of even more harmful, carcinogenic substances in reactions involving NO. For example: a proven, reliable and highly efficient technology for the separation of harmful nitrogen compounds from gases is selective catalytic reduction (SCR) of NOx with ammonia as a reagent.

One of the most acute problems in the modern world is the reduction of the environmental impact of emissions in terms of carbon dioxide.

Since the completeness of burning of organic substances is characterized by the content of carbon dioxide and water (to a greater extent), it is most important to consider methods for cleaning gases, including carbon dioxide. Briefly, the main methods for cleaning aerosols from dioxide are presented below:

- Water absorption. The method is simple and cheap, however, the cleaning efficiency is small, since the maximum absorption capacity of water is low.

- Absorption by solutions of ethanolamines: monoethanolamine is usually used as an absorber, although triethanolamine is more reactive, followed by regeneration of the absorbent at different pressures and further compression of carbon dioxide.

- The cold methanol is a good absorber of CO ₂ at 35 ° c.

- Purification by CaA type zeolites. The CO ₂ molecules are very small: 3.1A, therefore molecular sieves are used to extract CO ₂ from the gas.

An analysis of the methods used for cleaning industrial exhaust gases from harmful chemical compounds, the main of which are absorption, adsorption, catalytic and thermal, shows that the absorption ("wet") cleaning method is most acceptable for industrial gases cleaning from harmful chemical compounds. The use of wet cleaning requires minimal preliminary preparation of gas and the use of expensive catalysts or absorbents; it allows simultaneous cleaning of gaseous and mechanical components under mild temperature conditions.

There are various methods of multi-stage cleaning of aerosol particulate matter, which consists in the fact that in several stages the mechanical separation of particulate matter from an aerosol is carried out by deposition of particulate matter under the action of one or more forces - gravitational, inertial forces, Coriolis forces, centrifugal forces, electrostatic forces, applied to the deposited particles simultaneously or sequentially, and each previous stage cleans the inlet aerosol of solid particles so that the aerosol at the exit is acceptable th largest size fraction for the implementation of the next step.

The disadvantage of these methods is that their implementation for high-temperature aerosols, consisting of at least free-dispersed and coarse-dispersed aerosols, simultaneously emitted into the atmosphere does not provide temperature matching with the subsequent stage, or it is extremely technically difficult or unreasonably expensive or impossible.

The prior art methods and devices for wet cleaning and cooling gas (US 6042636, 03/28/1991; SU 1638482, 03/30/1991; SU 1533740, 01/07/1990; JPH 06212174, 02/08/1994; US 9504951, 11/29/2016) and methods and dry gas cleaning devices with gas flow cooling and sediment removal (AT 412533, 04/25/2005; WO 2016/182441, 11/17/2016; US 4305909, 12/15/1981; WO 2009/108983, 09/11/2009; CN 1033508, 28.06. 1989).

However, the indicated sources do not disclose multistage purification of the dispersed phases of high-temperature aerosols, in which the purification is not only mechanical, but also chemical, while for each subsequent purification step the temperature regime and particle size of the dispersed phases are consistent, and therefore proper purification is not achieved high temperature aerosols.

The technical problem to be solved by the proposed invention is to expand the arsenal of methods for cleaning dispersed phases of high-temperature aerosols, parameters whose characteristics provide high cleaning of high-temperature aerosols while reducing cleaning costs, reducing emissions of dispersed phases into the atmosphere, their controlled collection and removal, however, the continuity of the cleaning process is not violated.

The technical result achieved by the practical implementation of this invention is to increase the efficiency of the method and the quality of aerosol cleaning by achieving a deep degree of cleaning due to the coordination between the stages of cleaning temperature conditions, the volume and size of solid particles between stages, which leads to lower cleaning costs, reduce emissions of dispersed phases into the atmosphere and their collection, as well as the continuity of cleaning and creating the necessary conditions for the effective cleaning of aerosol from harmful chemical compounds.

The specified technical result is achieved in a method for cleaning high-temperature aerosols from harmful substances (including solid particles and substances hazardous to the environment and humans) in industrial emissions, in which a multi-stage purification of high-temperature aerosols is carried out, in which at least one stage of purification of the coarse-dispersed aerosol from the dispersed phase with the simultaneous controlled removal of the deposited solid particles from the area of their selection, recovery or utilization of heat and lasovannym one-stage or multi-stage lowering of the high temperature of the aerosol to the operating temperature to change the chemical composition of the aerosol and the proportions of the content of its components in the aerosol in different aggregate state at subsequent stages, and for mechanical cleaning of the aerosols from the dispersed phase.

High temperature aerosols consist of at least free and coarse aerosols.

The aerosol high temperature is lowered to the working temperature of the next stage.

The stage of purification of coarse aerosol, the recovery or utilization of aerosol heat, the coordinated lowering of the high temperature of the aerosol, for the next stage is carried out using the apparatus of the heat-mass transfer principle.

The stage of purification of coarse aerosol, the coordinated lowering of the high temperature of the aerosol, for the next stage is carried out by means of an apparatus with the functions of simultaneous: aerosol filtration, aerosol cooling, heat removal and ash and slag removal.

The cooling and heat recovery of the high-temperature aerosol in the first stage is carried out using the apparatus of the heat-mass transfer principle of the apparatus with the functions of the following: aerosol filtration, aerosol cooling, heat removal and ash and slag removal.

At each stage, at least one cleaning device is used, and coordination according to the result of the operation of one cleaning device is coordinated with at least several stages.

Lowering the high temperature of the aerosol is carried out to a temperature below the dew point, in this case harmful substances are emitted from the aerosol, which are at least in the liquid phase and consisting of at least solid particles.

The removal of harmful substances is carried out by controlled movement outside the zone in which the harmful substances are released from the aerosol for subsequent storage, disposal or processing.

At the previous stage, the volumetric amount of the large fraction output fraction is higher than at the next stage. With the claimed purification method, (due to a combination of various devices) step-by-step screening of the largest fractions relative to particles occurs in subsequent stages. The largest particles settle intensively in the first stage. In the second stage, you can adjust the cleaning to a specific particle diameter, for example, using a bag filter with a specific cell diameter larger than which the particle will not slip. With wet cleaning, the fraction of particles slipping through is very small or reduced to zero, thus at each previous stage the proportion of particles with a larger diameter and mass is higher than in the subsequent stage.

Additional heat recovery of the captured hot dispersed phase is carried out.

Also, by means of the apparatus of the heat-mass transfer principle of action, a coordinated decrease in the high temperature of the aerosol is carried out for the next stage, the range of permissible sizes of the dispersed phase, volumes of the dispersed phase in the aerosol, aerosol temperature and aerosol flow are set at the stage of designing the technological scheme and equipment.

The stage of cleaning coarse aerosol, the coordinated lowering of the high temperature of the aerosol, for the next stage is carried out by means of apparatuses, for example: a precipitation chamber with heat sink surfaces, a waste heat boiler, a shell-and-tube heat exchanger.

The cooling and use of heat of a high-temperature aerosol in the first stage is carried out by means of a heat and mass transfer apparatus or a group of apparatuses: a precipitation chamber with heat-removing surfaces, a waste heat boiler, and a shell-and-tube heat exchanger.

The precipitation of solid particles from the first and subsequent stages is carried out by controlled movement outside the zone in which the separation of solid particles from the aerosol is carried out for subsequent storage, or disposal, or processing. The output of the deposited solid particles is carried out, for example, by manual discharge from the storage hopper, by means of a pneumatic conveying system, by means of a screw conveyor or by a vacuum suction system.

The mechanical cleaning of high-temperature aerosols from the dispersed phase is carried out simultaneously with the cleaning of the aerosol from harmful substances that enter into a chemical reaction with water condensate formed by lowering the temperature of the aerosol, resulting in a mixture of precipitated solid particles and substances resulting from a chemical reaction followed by removal of the resulting mixture.

Changing the chemical composition of the aerosol and the proportions of the content of its components in the aerosol in a different state of aggregation is carried out by reducing the proportion of harmful substances in the aerosol, as well as by reducing the temperature of the aerosol to the temperature of condensation.

The efficiency of the method can be increased, for this, heat recovery of the captured high-temperature dispersed phase is used, and the generated heat is used to reduce the cost of the Method or for other purposes. The value by which the efficiency increases directly depends on the temperature of the trapped dispersed phase and the amount of trapped dispersed phase.

The consistency in the size of the fractions of solid particles, the permissible volume of solid particles in the aerosol at each stage, the temperature of the aerosol stream at each stage, and the degree of purification of the aerosol as a whole are carried out at the stage of designing a device that implements the Method.

When chemical cleaning of an aerosol does not exclude the use of additional devices, reagents and / or catalysts.

Create the necessary working conditions for the release of harmful chemicals.

The heat of the captured dispersed phase is recovered and the aerosol temperature is lowered to a temperature below the dew point.

The control of the volume of dispersed phases, as well as harmful chemical compounds, is carried out, for example, with periodic measuring devices for spot measurements in a certain area of the technological scheme, but it is most preferable to use stationary on-line aerosol monitoring systems after each stage or at the exit from the chimney .

Implementation for high-temperature aerosols, consisting of at least free-dispersed and coarse-dispersed aerosols, simultaneously emitted into the atmosphere is either extremely technically difficult, unreasonably expensive, or impossible. Such aerosols are characteristic, for example, for petrochemical or oil refining industries, in particular in catalytic processes. For such aerosols, the coordination of the cleaning stages, when each previous stage cleans the inlet aerosol of solid particles in such a way that the aerosol at the exit is admissible by the size of the largest fraction for the implementation of the next stage, is insufficient precisely because the aerosol is high-temperature and not every cleaning method having a limitation in operating temperature is suitable.

The implementation of cleaning high-temperature aerosols is the more expensive and resource-intensive, the higher the temperature of the aerosol. Therefore, in this case, to eliminate the noted drawback, it is necessary to reduce the temperature of the aerosol to acceptable values. In the technological process of catalytic production, the temperature of the aerosol is reduced using, for example, radiation air heaters, surface (gas) refrigerators (coolers), a waste heat boiler whose main function is to utilize excess heat by heating the coolant in the interest of its use in other technological processes. This reduces the cost of finished products.

The above methods for cooling aerosols have limitations, for example, in a classic recovery boiler, as a side effect (with respect to its main function of utilizing excess heat), a layer of deposited solid particles contained in the initial (hot) aerosol are accumulated, which accumulate on its heating surfaces and in the bottom, reaching critical volumes, which impede its further effective work subsequently. As a result, from a certain point in time, the deposited particles are again carried away with the flow of the passing aerosol, if the function of cleaning the inner surface and the function of controlled removal of the deposited particles are not provided. As a result, in subsequent stages, aerosol is subjected to mechanical cleaning at a lower temperature, but still containing coarse particles, which may be unacceptable for this subsequent stage.

The inventive method is characterized in that to reduce emissions of dispersed phases into the atmosphere and their collection, as well as the continuity of the cleaning at the first stage of cleaning the dispersed phase, including solid particles are separated from the coarse aerosol simultaneously with lowering the temperature of the aerosol, recovery or utilization of the heat of the aerosol, and the removal of the trapped dispersed phase outside the working area of the apparatus; solid particles extracted from the aerosol at each stage are controlled and collected outside the zone in which the solid particles are released from aerosol and create the necessary conditions for subsequent purification from harmful chemicals, in which the mechanical cleaning of high-temperature aerosols from fine phase with simultaneous cleaning of the aerosol from harmful substances that enter into a chemical reaction with water condensate formed by lowering the temperature of the aerosol, resulting in a mixture of precipitated solid particles and substances resulting from a chemical reaction with subsequent removal of the resulting mixture, i.e. at this stage of purification, the binding of substances that must be removed from the aerosol occurs through a particular chemical reaction (hereinafter chemical purification). Traditionally, chemical cleaning uses substances that were not present in the aerosol prior to this cleaning step. A distinctive feature of the proposed cleaning method is that when the temperature of the aerosol is lower than the dew point, no additional substances are required for chemical cleaning. Chemical cleaning of the aerosol is carried out due to and due to the appearance of condensate during cooling of the aerosol. Condensation forms from the moment the dew point is reached. The resulting condensate enters into a chemical reaction with harmful substances (harmful (reacting) substances are in the same volume (mixed, that is, mixing of harmful substances in a gaseous state and water condensate is mixed). The result of this reaction is removed from the reaction zone. All reagents are contained in the aerosol itself, and the chemical reaction begins when the dew point is reached, due to which the aggregate state of the aerosol changes and gas with impurities and water condensate (liquid) are obtained. chemical reaction with water condensate, the harmful substance “binds” and becomes part of the new substance (in liquid state). The withdrawal of this new substance (regardless of its usefulness or harmfulness) means the removal of the harmful substance that was previously contained in the initial aerosol in the gaseous state from the initial aerosol Thus, the specific composition of the aerosol does not matter, since it is important for the claimed method that there are solid particles in the aerosol that are removed mechanically, and chemical compounds that are removed by a chemical reaction involving condensate and these impurities. This is achieved by coordinating the stages of cleaning according to particle size and temperature.

Due to the consistency of working conditions between the stages, the process of cleaning the initial aerosol is cheaper and the output aerosol contains a significantly smaller volume of dispersed phases.

The invention is illustrated by examples of the implementation of the claimed method of purification from solid particles of high-temperature aerosols and drawings, where in FIG. 1-19 illustrates the prior art: FIG. 1 - gravitational deposition; FIG. 2 - gravitational deposition in a gas channel; FIG. 3 - gravitational deposition in a cylindrical collector; FIG. 4 - venturi scrubber; FIG. 5 - vortex dust collector; FIG. 6 - dynamic dust collector; FIG. 7-9 - dust chamber; FIG. 10 - dust precipitation chamber; FIG. 11 - louvered ash collector; FIG. 12 - inertial dust collector conical type; FIG. 13 - rotary dust collecting unit; FIG. 14 - bag filter; FIG. 15 - installation of multi-stage cleaning; FIG. 16 - dust collector-classifier; FIG. 17 - charging and deposition mechanism in the electrostatic precipitator; FIG. 18, 19 is an electrostatic precipitator, and in FIG. 20-23 - the essence of the claimed invention: FIG. 20 - types of methods used depending on the size of the dispersed phase of the aerosol; FIG. 21 - a waste heat boiler for flexible process management; FIG. 22 - a waste heat boiler with a superheater; FIG. 23 is a schematic diagram of a bag filter.

Referring to FIG. 20 methods allow achieving the necessary degree of aerosol purification from solid particles, but they may have limitations on the operating temperature, i.e. coordination of this stage of cleaning by aerosol temperature is required. To ensure the required temperature before this stage, choose a method of lowering the temperature by installing an apparatus with the function of cooling the dry or wet type aerosol, direct, contact type or through an intermediate surface. The above-mentioned way is the coordination of the stages according to the necessary conditions for the correct performance of their functions at each stage.

Table 1 below shows examples of different methods for use at different aerosol temperatures at a particular stage. Examples of implementing the method by compiling cleaning methods, cooling high-temperature aerosols, utilizing and recovering heat from aerosols, and removing captured substances outside the treatment zone are given. Moreover, for each stage, choose one or several devices; and coordination on the result of the operation of one device occurs both with one and with several stages.

In the examples described below, the stage of the final moisture drying of the cooled and purified aerosol before being discharged into the atmosphere is not considered, since this stage is not the goal of this work and can be implemented depending on the needs in any way.

Example 1. Initial data: The initial aerosol can be formed as a result of the combustion of combustible substances, for example, liquid fuel; coke in the regenerator of catalytic processes, metallurgical furnaces; or in firing and drying processes in cement production, as well as other high-temperature processes.

For definiteness, we consider the case when an aerosol is formed as a result of combustion of coking products on the surface of spent catalysts in the regenerator of the catalytic process. The aerosol consists of coarse and fine aerosols with a solids content of up to 1100 mg / nm3. The temperature of the initial aerosol reaches 650 ° C at the outlet of the regenerator.

It is required to cool the aerosol to a temperature of 220-2500 C, to utilize the heat of the cooled aerosol and reduce the solids content to a value of not more than 10 mg / nm3.

To solve the tasks:

in the first stage, two heat recovery boilers are used in parallel for flexible process control, see FIG. 21. They contain a heat-exchange surface 67, baffle plates 68 and an air dilution chamber 69 and perform the function of: heat-mass transfer apparatus for cooling the aerosol from 650 to 250-220 ° C; aerosol heat recovery and steam generation function; the function of separating coarse particles and removing captured particles from the selection zone. The characteristics of waste heat boilers are calculated in accordance with well-known calculation methods (for example, we will use the methodology from the publication “Thermal Calculation of Boilers” (normative method), edition 3 revised, supplemented by JSC VTI and JSC NPT TsKTI named after Polzunov., St. Petersburg 1998 g.).

In the first stage, in addition to cooling the aerosol, intense precipitation of the largest dispersed particles occurs, including fragments of spent catalysts with products of incomplete combustion of coke with a complex chemical composition.

At the next stage (mechanical cleaning of high-temperature aerosols from the finely dispersed phase), an aerosol fine filter is used in the form of bag filters with the functions of: cleaning the aerosol from solid particles from 1100 to 10 mg / nm3; removal of trapped particles from the cleaning zone. The working temperature of bag filters is limited to no more than 270 ° C. The characteristics of the bag filter are selected and calculated according to well-known methods (for example, we use the method from the publication “Methods and systems for gas purification”, Barkan M.Sh., Pashkevich MA, Dompalm E.I., Burmistrova M.M., Publishing House -to: St. Petersburg State Mining Institute named after G.V. Plekhanov, 2006).

All trapped particles are removed from the cleaning zone, thereby re-entrainment of the deposited particles is minimized, while the temperature of the aerosol is not lowered below the dew point. Particulate matter is removed outside the purification zone by means of a pneumatic conveying system, the characteristics of which are calculated according to well-known methods (for example, we will use the method of AI Voloshin, “Mechanics of pneumatic conveying of bulk materials,” NAUKOVA DUMKA, 2001).

After two stages in the aerosol, the ratio of solid to gaseous components changes, i.e. components with different state of aggregation and chemical composition.

The cooled and purified aerosol enters the chimney with a temperature of 220 ° C and a solids content of up to 10 mg / nm3.

Example 2 Initial data: The initial aerosol is formed, for example, during the regeneration of the catalyst in the regenerator of the catalytic cracking unit. As a result, the aerosol consists of products of incomplete combustion of deposits, among which harmful sulfur oxides are present, as well as a dispersed phase of solid particles with sizes from fractions of a micrometer to 160 microns and quantities up to 600 mg / nm3. Aerosol temperature 700 ° C.

It is required to reduce the content of the dispersed phase to below 5 mg / nm3. In addition, it is necessary to lower the temperature below the dew point temperature and convert the resulting energy into steam; in addition, it is necessary to capture and remove corrosive sulfur oxides from the aerosol cleaning zone.

To solve the tasks:

in the first stage we will use a recovery boiler, see FIG. 21. It performs the function of a heat and mass transfer apparatus to lower the temperature of the aerosol and produce high-energy steam. In addition, the waste heat boiler performs the function of cleaning the aerosol from solid particles with the aid of the fenders included in its composition, which intensify the beating of solid particles. These devices are in the form of plates installed inside the recovery boiler. For example, the particle density, porosity and other characteristics are known, we can calculate that particles of less than 30 microns have a low mass, low gravitational sedimentation rate and are able to slip through the aerosol stream to the next stage, and particles more than 100 microns have several times the mass more and this is enough for their deposition under the action of gravity and inertia which is created in the process of inertial bounce from the internal surfaces of the waste heat boiler. Thus, knowing the percentage of fractions with a diameter of more than 100 microns, it is possible to calculate the degree of aerosol purification in the waste heat boiler from the coarse fraction. In addition, to increase the efficiency of deposition of solid particles from the aerosol, an additional surface in the form of studding and fins on the heat exchange surface can be used, which further increases the efficiency of heat removal. In this case, the cleaning of the deposited particles from the internal surfaces is carried out by a gas-pulse cleaning system by periodically shaking. The characteristics of the recovery boiler are calculated in accordance with well-known calculation methods (for example, we use the methodology from the publication “Thermal Calculation of Boilers” (normative method), edition 3 revised, supplemented by JSC VTI and JSC NPT TsKTI named after Polzunov., St. Petersburg 1998 g.). Lowering the temperature to the operating value for the subsequent cleaning stage, in our case, to 200 ° C, is provided either in the recovery boiler itself or in a separate recovery boiler, which implements a separate cleaning stage. By fulfilling the above items, we ensure coordination with the subsequent stage in terms of aerosol temperature. Moreover, this technique allows you to calculate both options. We will choose the most economically more profitable option. The volume of solid particles in the bottom of the recovery boiler is controlled by a level gauge. The coarse fraction, with a large mass and particle size sufficient for natural deposition under the action of gravity and inertia, is beaten off the baffle surfaces and fall into the bottom of the recovery boiler.

The heat of deposited solids in the bottom of the recovery boiler is recovered by installing, for example, an additional heat exchange surface, see FIG. 21, in the form of a hollow lamellar or tubular structure, which is in contact with the external surface with solid particles, and a heat transfer fluid flows through the internal space, which removes heat from solid particles.

Precipitated solid particles are removed outside the waste heat boiler through a pneumatic conveying system, the characteristics of which are calculated according to well-known methods (for example, we will use the method of AI Voloshin, “Mechanics of pneumatic conveying of bulk materials,” NAUKOVA DUMKA, 2001). Fulfilling the above points, we ensure coordination with the subsequent stage in terms of particle size and volume of coarse fraction;

At the second stage, we will use 2 devices: an electrostatic precipitator for aerosol cleaning and an economizer section for aerosol cooling. The principle of electric gas purification is based on the ionization of gas passing in the electrode space with a non-uniform electric field of high tension, causing ionization of the gas medium. Being in the ionized space, dust particles (fog) acquire an electric charge (usually an excess negative) and are deposited on an electrode of the opposite sign. The characteristics of electrostatic precipitators are calculated according to well-known methods (for example, we use the methodology from the publication “Calculation of ash collection and slag ash collection systems”, Vilensky TV, Publishing House: ENERGY, 1964). The degree of aerosol purification after the electrostatic precipitator reaches up to 90%. To coordinate with the next stage in temperature, we use the economizer section made in the form of tube bundles, inside of which a heat agent is let in the form of water, which cools the aerosol, the whole structure is made in a steel case. At the same time, the economizer section is connected to the recovery boiler and performs the function of primary heating of boiler water. The economizer characteristics are calculated using similar methods for calculating waste heat boilers, the links to which are given in this example. The temperature of the aerosol at the exit of this stage is below 150 ° C;

In the third stage, we use condensation equipment made in the form of a mono- or multiblock type heat exchanger with the function of removing sludge from the heat exchanger. During condensation, liquid vapors envelop and capture the smallest dispersed particles with them. At the same time, dispersed dust particles coated with a condensate film have good adhesive ability, thereby increasing the efficiency of coagulation of such particles with each other. The contact heat exchange surface can be made in the form of hollow plates, inside which a refrigerant moves, which removes the heat of the aerosol, and outside the heat transfer plates, condensation of harmful substances occurs at a temperature below the dew point. The characteristics of the condensation heat exchanger are calculated according to well-known methods (for example, we will use the method from the publication “Heat Exchangers and Condensing Devices”, S. Berman, Publishing House: MASHGIZ, 1959). In addition, the contact surface of the plates with the aerosol is coated with protective coatings to protect against aggressive environments. As protective coatings, coatings based on silicon oxides, up to 100 microns thick, produced by sol-gel technology, which form a strong and relatively elastic matrix that withstands thermal expansion in wide temperature ranges and have good thermal conductivity, are used, and they are used as a dispersed phase. metal oxides. The coatings form a durable, gas-tight layer on the heat exchange surface. At temperatures lower than 150 ° C, vaporous water and sulfur oxides react with acid condensation. Acidic condensate is collected and discharged into a separate receiving tank for re-irrigation in the recirculation loop, and excess is discharged into the transport line to drain acidic sludge. Drop traps are used to trap drops after condensation equipment. The characteristics of the transport systems for removing sludge (i.e. mixtures of bulk and liquid components) are calculated according to well-known methods (for example, we use the method from the publication "Calculation of ash collection and slag ash collection systems", Vilensky TV, Publishing House: ENERGY, 1964).

At the same time, the aerosol is cooled to a temperature below 100 ° C, for example, to 40 ° C, depending on the requirements. Thus, at each stage, agreement is reached on the operating temperature, size of the fractions, and volume of the dispersed phase in the aerosol.

Example 3. Initial data: The initial aerosol can be formed as a result of the process of sublimation of charge and metal elements, and mechanical entrainment of melt drops and solid charge particles in open-hearth furnaces of the metallurgical industry. Aerosol composition: harmful chemicals, for example, SOx, NOx, COx, as well as the dispersed phase of solid particles, 85% of iron oxides, with particle sizes from fractions of a micrometer to conglomerates with sizes up to 100 microns and a total amount of dust up to 10000 mg / nm ³ . Aerosol temperature 600 ° С in the furnace hog before cleaning.

It is required to reduce the temperature of the aerosol to 100-80 ° C, to utilize the heat of the aerosol, to reduce the content of the dispersed phase to a value no higher than 10 mg / nm ³ , while it is necessary to isolate harmful and corrosive compounds from the aerosol.

To solve the tasks: at the first stage we will use a waste heat boiler, see Fig.22. It contains a heat exchange surface 67, baffle plates 68 and an air dilution chamber 69 and functions as a heat and mass transfer apparatus to lower the temperature of the aerosol and produce high-energy steam. In addition, the recovery boiler performs the function of cleaning the aerosol from solid particles. We carry out the function of cleaning coarse particulate matter at the inlet of the waste heat boiler by installing, along the direction of the aerosol, a vertical baffle section in which the passage openings are staggered due to which the particles are intensively beaten off during turbulization of the aerosol stream and multiple changes in the movement of aerosol flows , which leads to intense inertial rebound of particles and their deposition. Due to the installation of the baffle section in front of the heat exchange pipes, the amount of deposited particles on the pipes is reduced and the steam production of the recovery boiler is more efficient and the pipe service life is extended, because reduced erosion by solid particles on pipes. In this case, the cleaning of the deposited particles from the internal surfaces is carried out by a gas-pulse cleaning system by periodically shaking. The characteristics of the recovery boiler are calculated in accordance with well-known calculation methods, taking into account the installed fenders (for example, we will use the methodology from the publication “Heat and Power Equipment and Heat Supply” Methodological Instructions. Compiled by T. Gerasimenko, TEREK Publishing House, 2014 g.). Lowering the temperature to the operating value for the subsequent cleaning stage, in our case, up to 240 ° C, is provided in the recovery boiler itself. By fulfilling the above items, we ensure coordination with the subsequent stage in terms of aerosol temperature. A coarse fraction, with a relatively large mass and particle size sufficient for natural deposition under the action of gravity and inertia, falls into the bottom of the recovery boiler.

The heat of deposited solids in the bottom of the recovery boiler is recovered by installing, for example, an additional heat exchange surface, see FIG. 21, in the form of a hollow lamellar or tubular structure, which is in contact with the external surface with solid particles, and a heat transfer fluid flows through the internal space, which removes heat from solid particles.

Precipitated solid particles are removed outside the waste heat boiler through a pneumatic conveying system, the characteristics of which are calculated according to well-known methods (for example, we will use the method of AI Voloshin, “Mechanics of pneumatic conveying of bulk materials,” NAUKOVA DUMKA, 2001). Fulfilling the above points, we ensure coordination with the subsequent stage in terms of particle size and volume of coarse fraction;

In the second stage we will use 2 devices. Dust collection cyclone and economizer section for aerosol cooling and heat recovery. A cyclone, an apparatus that collects dust under the action of centrifugal forces arising in a rotating stream of dusty gases. Relatively large dust particles are thrown away by the stream to the cyclone wall, inhibit their motion due to friction and are gradually deposited in the lower part of the apparatus. The design feature of the cyclone is the flow of gas into it tangentially to the cylinder; the rotation of gases occurs from top to bottom (in the cylindrical part), and in the conical part of the cyclone an external rotating vortex is formed. The degree of purification in the cyclone reaches up to 90%. The characteristics of the cyclone are calculated in accordance with well-known calculation methods (for example, we will use the methodology from the publication Methodological Instructions "Dust Collectors for Purifying Air Emissions. Calculation of Cyclones" in the discipline "Fundamentals of Ecology" for students of all specialties of full-time and extramural studies / Comp. B .V. Sevrikov, A.A. Nikitin. - Sevastopol: Publishing House of SevNTU, 2008.). The economizer characteristics are calculated using similar methods for calculating waste heat boilers, the links to which are given in this example. The temperature of the aerosol at the exit of this stage is below 140 ° C.

Fulfilling the conditions of stage 2, we ensure coordination with the subsequent stage in terms of particle size, volume of the dispersed fraction and aerosol temperature;

In the third stage, we use a high-pressure venturi scrubber. This is one of the most effective devices for wet cleaning of aerosol from solid particles and absorption of gaseous impurities at low temperatures. Since at this stage the temperature of the aerosol is below the dew point, the execution of the internal structural elements must be protected from the effects of chemical aggressive environments. The venturi scrubber is equipped with a drop catcher. The characteristics of the Venturi scrubber are calculated in accordance with well-known calculation methods (for example, we will use the method from the publication “Designing of dust and gas cleaning devices. / Ziganshin MG, Kolesnik A.A., Posokhin V.N./M .:“ Ecopress - 3M ”, 1998 - 505 s.) The degree of purification from solid particles after all stages is up to 99%.

Thus, at each stage, agreement is achieved on the basic necessary working conditions, such as temperature, size of fractions and volume of the dispersed phase in the aerosol, for the implementation of the next stage and the achievement of the best result.

Example 4. Initial data: Aerosol is formed as a result of oxygen purge of cast iron of converter production. As a result, dust predominantly aerosol consists of oxides of iron, silicon, aluminum, manganese, with sizes ranging from fractions of a micron to 5 microns and the amount of up to 250 mg / ^Nm3. In addition, the aerosol consists of carbon oxides and sulfur, hydrogen sulfide and fluorine with chlorine. The temperature of the aerosol before cleaning is 1300 ° C.

It is required to reduce the content of the dispersed phase to below 5 mg / nm ³ . In addition, it is necessary to lower the temperature below the dew point temperature and convert the resulting energy into steam. It is also required to catch and remove corrosive sulfur oxides outside the aerosol cleaning zone, and reduce, for example, NOx content to 95%.

To solve the tasks: in the first stage we will use a pre-installed superheater for generating hot steam and a waste heat boiler, see Fig. 22. and the description is given in stage 1, in example 3, see above. Lowering the temperature to the operating value for the subsequent stage of cleaning, in our case, up to 300 ° C, is provided by 2 devices. The characteristics of the recovery boiler are calculated in accordance with well-known calculation methods, taking into account the installed fenders (for example, we will use the methodology from the publication “Thermal calculation of boilers” (standard method), edition 3 revised, supplemented by JSC VTI and JSC NPT TsKTI named after Polzunov ., St. Petersburg 1998). By fulfilling the above items, we ensure coordination with the subsequent stage in terms of aerosol temperature. The volume of solid particles in the bottom of the recovery boiler is controlled by a level gauge. A coarse fraction with a large mass and particle size sufficient for natural deposition by gravity and inertia falls into the bottom of the recovery boiler.

The heat of deposited solids in the bottom of the recovery boiler is recovered by installing, for example, an additional heat exchange surface, see FIG. 21, in the form of a hollow lamellar or tubular structure, which is in contact with the external surface with solid particles, and a heat transfer fluid flows through the internal space, which removes heat from solid particles. Precipitated solid particles are removed outside the waste heat boiler through a pneumatic conveying system, the characteristics of which are calculated according to well-known methods (for example, we will use the method of AI Voloshin, “Mechanics of pneumatic conveying of bulk materials,” NAUKOVA DUMKA, 2001)., Performing the above items , we ensure coordination with the subsequent stage in terms of particle size and volume of the coarse fraction;

In the second stage we will use 2 devices: a complex purification device from harmful substances and an economizer for cooling the aerosol., A device using the technology of complex purification of aerosol from particulate matter and NOx, in our case, using CERCAT® technology from Maguin (Official website of the company http: / /maquin.com/en/activities/environment/cercat-filter/; a detailed description of the technology is available at https://tri-mer.com/pdf-files/ceramic-filter-systems.pdf). This design has operating temperature limits for effective cleaning. Operating temperature values range from 230 to 370 ° C. The entire aerosol purification installation at this stage can be performed in a standard design for bag filters, where nozzles of porous permeable high-temperature ceramics with a deposited catalyst layer for the reduction of nitrogen oxides from aerosol are used as filter elements, a schematic diagram is shown in FIG. 23, in which under the position 70 the bag filter is reflected, under 71, a hopper with additives; under 72 - ash and slag transport line.

To carry out the reduction reaction of nitrogen oxides, a certain amount of reagents is injected into the aerosol stream to the filter, which are mixed with the aerosol and pass through the ceramic filter elements as a mixture. In the presence of a catalyst on the filter elements, a reduction reaction to N ₂ occurs. In this case, the contained solid particles in the aerosol are retained on the surface of the filter elements, and dust is shaken off the surface by a gas-pulse installation. Thus, at this stage, the aerosol is cleaned from harmful NOx impurities in the aerosol by 98% and from solid particles to a value below 10 mg / nm3.

The economizer characteristics are calculated using similar methods for calculating waste heat boilers, the links to which are given in this example. The temperature of the aerosol at the exit of this stage is below 140 ° C.

The temperature of the aerosol at the outlet of the stage exceeds the temperature of the dew point and corresponds to the operating value for the subsequent stage; In the third stage, we use condensation equipment made in the form of a mono- or multiblock type heat exchanger with the function of removing sludge from the heat exchanger. During condensation, liquid vapors envelop and capture the smallest dispersed particles with them. At the same time, dispersed dust particles coated with a condensate film have good adhesive ability, thereby increasing the efficiency of coagulation of such particles with each other. The contact heat exchange surface can be made in the form of hollow plates, inside which a refrigerant moves, which removes the heat of the aerosol, and outside the heat transfer plates, condensation of harmful substances occurs at a temperature below the dew point. The characteristics of the condensing heat exchanger are calculated according to well-known methods (for example, we will use the method from the publication “Heat Exchangers and Condensing Devices”, Berman S.S., Publishing House: MASHGI 3.1959). In addition, the contact surface of the plates with the aerosol is coated with protective coatings to protect against aggressive environments. As protective coatings, coatings based on silicon oxides, up to 100 microns thick, produced by sol-gel technology, which form a strong and relatively elastic matrix that withstands thermal expansion in wide temperature ranges and have good thermal conductivity, are used, and they are used as a dispersed phase. metal oxides. Coatings form a durable, gas-tight layer on a heat-exchange surface. At temperatures lower than 150 ° C, vaporous water and sulfur oxides react with acid condensation. Acidic condensate is collected and discharged into a separate receiving tank for re-irrigation in the recirculation loop, and excess is discharged into the transport line to drain acidic sludge. Drop traps are used to trap drops after condensation equipment. The characteristics of the transport systems for removing sludge (i.e. mixtures of bulk and liquid components) are calculated according to well-known methods (for example, we use the method from the publication "Calculation of ash collection and slag ash collection systems", Vilensky TV, Publishing House: ENERGY, 1964).

At the same time, the aerosol is cooled to a temperature below 100 ° C, for example, to 40 ° C, depending on the requirements. The degree of aerosol purification after all stages is more than 99%.

Thus, at each stage, agreement is reached on the operating temperature, size of the fractions, and volume of the dispersed phase in the aerosol.

Claims (13)

1. A method of cleaning high-temperature aerosols from harmful substances in industrial emissions, characterized in that a multi-stage cleaning of high-temperature aerosols is carried out, in which at least one stage of cleaning the coarse-dispersed aerosol from the dispersed phase is carried out with the simultaneous controlled removal of the deposited solid particles from their area heat generation and recovery or utilization and a coordinated one-stage or multi-stage reduction of the aerosol high temperature to a temperature of water condensate formation for changing at the subsequent stages the aerosol chemical composition and proportions of the content of its components in the aerosol in a different aggregate state by entering into a chemical reaction of harmful substances with water condensate and for mechanical cleaning of aerosols from the dispersed phase, while mechanical cleaning of high-temperature aerosols from the dispersed phase carried out simultaneously with the cleaning of the aerosol from harmful substances that enter into a chemical reaction with water condensate, and the stage of purification ki coarsely dispersed aerosol coordinated lowering high temperature aerosol for subsequent step performed by the device with simultaneous functions: filtering an aerosol spray cooling, and teplootvedeniya zoloshlakootvedeniya. 2. The method according to p. 1, characterized in that the high-temperature aerosols consist of at least free-dispersed and coarse-dispersed aerosols. 3. The method according to p. 1, characterized in that they produce a decrease in the high temperature of the aerosol to the working temperature of the next stage. 4. The method according to p. 1, characterized in that the stage of cleaning coarse aerosol, recovery or utilization of heat of the aerosol, the coordinated lowering of the high temperature of the aerosol for the next stage is carried out by means of a heat and mass transfer principle of operation. 5. The method according to p. 1, characterized in that the cooling and heat recovery of the high-temperature aerosol in the first stage is carried out by means of a heat and mass transfer apparatus with simultaneous functions: aerosol filtration, aerosol cooling, heat removal and ash and slag removal. 6. The method according to claim 1, characterized in that at each stage at least one device is used, and coordination according to the result of the operation of one device is coordinated with at least several stages. 7. The method according to p. 1, characterized in that the lowering of the high temperature of the aerosol is produced to a temperature below the dew point. 8. The method according to p. 7, characterized in that when lowering the high temperature of the aerosol to a temperature below the dew point of the aerosol emit harmful substances that are at least in the liquid phase. 9. The method according to p. 8, characterized in that the harmful substances released from the aerosol consist of at least solid particles. 10. The method according to p. 9, characterized in that the output of the selected harmful substances is carried out by controlled movement outside the zone in which the harmful substances are released from the aerosol for subsequent storage, or disposal, or processing. 11. The method according to p. 1, characterized in that at the previous stage, the volumetric amount of the output fraction of large diameter is higher than at the next stage. 12. The method according to p. 1, characterized in that they produce additional heat recovery of the captured hot dispersed phase. 13. The method according to p. 1, characterized in that the change in the chemical composition of the aerosol and the proportions of the content of its components in the aerosol in a different state of aggregation is carried out by reducing the proportion of harmful substances contained in the aerosol.

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