Equipment for air purification from dust. Cyclones, filters, dust collectors. Device diagram, operating principles. Industrial cyclone dust collector for cleaning the air from dust Dust extraction cyclone device technical description

Owners of small workshops and just home craftsmen often have to deal with the problem of air purification after intensive work on wood processing and sanding. metal surfaces etc. Conventional room ventilation will not help here; you will need to install specialized equipment. With known skills, you can do it yourself.

Purpose and characteristics of cyclones

The cyclone is a specialized air purification unit (although similar units also used as chip ejectors, sawdust and other means for waste removal).

As air purifiers, industrial cyclone designs must provide suction and dust removal with an efficiency of at least 85...90%, when removing dust fragments with sizes of at least 10...12 microns. They are equipped various designs filters. The most effective are electrostatic precipitators, which simultaneously remove static electricity charges from dust particles.

The principle of operation of the cyclone is as follows. In snail-shaped entrance space Air enters the cyclone at high speed (up to 20 m/s), for which fans are usually used. The air containing dust particles is swirled and then enters the conical cavity of the device. Features of the geometric structure of the cyclone cause a gradual increase in the speed of the air flow containing dust and other waste. During this process, heavier dust particles self-separation from lighter ones. The former settle to the bottom, and the latter, moving in a cone-shaped space, end up in the dust collector, from where they can be easily removed using a bucket or sealed container. The purified air is released into the atmosphere through the pipe.

The number of cyclones, depending on the requirements for the quality of dust removal, can be made different: there are groups of three, four and even eight single cyclones.

Operational requirements for cyclones include the following parameters:

1. permissible dispersion of particles that enter the cyclone, microns.
2. the efficiency of the process, which is expressed in the maximum weight concentration of particles after dust removal, in g/mm 3 ;
3. cyclone productivity, m 3 /h;
4. limit temperature of air or gas entering the cyclone socket (more typical for gas cleaning systems than dust removal systems) - usually up to 400...600 °C;
5. internal diameter of the cyclone, mm.

In addition to purely design requirements, there are also conditions quality installation air purification devices. For example, if the gaps in the air duct connections are exceeded, air leaks often occur, during which the performance of dust separation from air sharply decreases. The permissible suction value should not be more than 6...8%.

Cyclones not only remove dust from the surrounding air, but can also provide clean air into the room.

Construction of a household cyclone

There are no universal cyclones for performing various cleaning operations. For example, the chip ejector must have increased strength of the pipe walls, which will prevent premature wear. Regarding the cyclone intended for collecting and removing sawdust, it is important to provide minimal losses in the intake air ducts. Providing a cyclone for the purpose of cleaning the air from cement dust arising in construction work, special attention pay attention to filter design.

IN living conditions The most universal are cyclones that clean the air from coarse dust. By changing the design of the filters, such devices can be made for dust removal purposes, as a chip suction unit, or for cleaning the air from sawdust in a woodworking workshop (for example, at an operating sawmill).

The components of such a unit are:

• body - includes conical and cylindrical parts, and the shape of the conical part has a predominant influence on the quality of the process;
• pipe - one or more, where the original polluted air enters;
• an exhaust pipe designed to remove dust-free air;
• inlet filter (or their system) as a chip suction device;
• receiving bucket;
• drive motor;
• fan.

All of the listed parts/assemblies can be purchased or made by yourself.

Motor selection

Since a homemade cyclone is installed in a workshop, the main parameter of the engine is its power and the number of rotor revolutions. If there is a fan, motor power special significance does not, since dust particles still end up in a working machine, sawmill, etc. will not hit. However, the power and diameter of the cyclone scroll must be interconnected. With a snail wheel diameter of up to 300...350 mm, a high-speed (required!) engine of up to 1.5 kW is quite suitable. With smaller diameters, the power may be lower, but the cleaning performance will also decrease. Therefore, if there is a metalworking machine in the workshop, a motor of 1 kW or more is accepted.

The power of the electric motor increases significantly if you plan to build it yourself homemade device outside the premises. Free space will increase, but the cleaning efficiency will decrease, mainly due to losses in the air ducts. It is also worth noting that during the cold season, such a homemade cyclone will effectively “pull” heat from the workshop.

A good option is to purchase an electric motor complete with a receiving volute, the number of which determines the consumer capabilities of a homemade air purification system. The most common for household use The parameters of the snails and the electric motors recommended for them are given in the table:

The systems are supplied with rubber vibration isolators. They are capable of creating working pressure from 0.8 kPa and above.

When choosing (or making with your own hands) a snail, preference should be given to a radial air intake pattern rather than a tangential one.

In the latter case, unproductive losses increase for a homemade snail, and the inertia of the particle selection method for the option with a chip suction device will be very low.

When choosing a motor, it is necessary to take into account that the speed of air movement in the device cannot be less than 2.5...3 m/s. If cleaning is unsatisfactory, the elements of a homemade cyclone like a chip suction device (filter, bucket) quickly become clogged with shavings, sawdust and other small waste.

Manufacturing of cyclone elements

On specialized Internet forums you can find drawings of all components of the unit, which are available for making them yourself. Using improvised means, a household (or better yet, an industrial) vacuum cleaner is often remade. Additionally required:

• a set of hoses made of translucent corrugated material (this will facilitate visual control of dust particles settled inside). For chip extraction, rubber hoses are more practical;
• a soundproofing box that will perform two functions - it will reduce the noise level in the workshop, and additional protection protect all machines and power tools located there from static electricity periodically accumulated by dust. For this purpose, you can make the box yourself from plywood, and decorate the inside with any type of sound insulator;
• air ducts for purified air: assembled with your own hands from a thin aluminum sheet and connected to each other with folds;
• waste collection container - can be made from an ordinary construction bucket with a capacity of 20 liters or more, which is sealed with the body of a homemade cyclone using a corrugated hose;
• filter (you can use a filter from trucks), which is installed on the outlet pipe.

A vacuum cleaner converted with your own hands for dust removal needs is checked: first for idling, passing normal air through the system, and then connecting the vacuum cleaner to the operating machine.

Single, group and battery cyclones are classified as centrifugal-type inertial dust collectors. Dust collection in cyclones is based on the use of centrifugal forces that arise when the gas flow rotates. This movement is created either by tangential or spiral supply of gases into the cyclone body, or due to the use of twisting devices for the axial supply of gases to the cyclone.

Single cyclones are designed for sedimentation of coarse dust, sawdust and shavings. Their principle of operation is based on centrifugal force, under the influence of which suspended particles, pressing against the outer cylindrical or conical walls of the dust separator, lose speed and fall through the lower conical part to the outlet - the dust collector. The fine dust purified in the air is thrown upward through the outlet pipe. If used incorrectly, flammable and explosive dust can explode in cyclones from static electricity discharges, so install them in production premises forbidden. If, when calculating the degree of purification, it turns out that the required degree is not provided, it is possible to install cyclones in two successive stages.

Group cyclones are obtained by combining single cyclones. Typically, in a group design, cylindrical cyclones of small sizes are used, installing them in 2, 4, 6 and 8 identical cyclones in a group with a one- or two-row rectangular arrangement (Fig. 2, a) or in 10, 12 and 14 single cyclones in a group with circular arrangement (Fig. 2,b).

When cleaning large volumes of ventilation emissions, it is more rational to install group cyclones of smaller sizes instead of one large cyclone.

In small-sized cyclones (multi-cyclones), the magnitude of the centrifugal force is inversely proportional to the distance of the particle from the cyclone axis, therefore, in small-diameter cyclones the magnitude of this force increases. In addition, along with a decrease in the size of the cyclone, the distance from the inner cylindrical to the outer wall of the cyclone decreases, i.e., the path of the particle before its deposition decreases. Cyclones of smaller diameter have a high purification coefficient, so they are used to collect fine, dry and light dust from air and gases. The productivity of a multicyclone is limited, so several cyclones are combined into groups or batteries, which are called group and battery.

The industry produces several types of cyclones. The most widely used cyclones are the designs TsN, TsN-11, TsN-15, TsN-15U, TsN-24. When choosing and calculating cyclones, the characteristics of the collected dust should be taken into account: the minimum diameter of dust particles, abrasiveness, adhesion, temperature and humidity of gases, corrosive Rosiness, fire and explosion hazard. Collected dust from the bunkers is removed through dust unloading devices - dust gates.

Figure 2. Group cyclones: a - TsN-11 on a pedestal (for unloading dust from the dust collector of a car); b-- NIIOGaz TsN - a group of 10 or more cyclones; 8 -- battery cyclone; 1 -- inlet pipe; 2 -- cyclonic elements; 3 -- partition: g -- battery cyclone element: 1 -- frame; 2 -- outlet pipe; 3 - screw blades.

The most important requirement for a dust seal is its tightness. Leakage of the dust seal leads to air leaks into the hopper, and then through the dust outlets into the cyclones, since in accordance with the requirements of industrial sanitation, most cyclones operate under vacuum, the degree of cleaning is sharply reduced.

Figure 3. Louvre-cyclone dust collector: 1 - dust collector; 2 -- cyclone; 3 -- blinds

Battery cyclones (Fig. 2, c) are dust collecting devices made up of large number cyclone-new elements of small diameter , combined in one housing and having a common gas supply and outlet, as well as a common collection hopper for collected dust.

Gas purification in battery cyclones is based on the use of centrifugal forces. Unlike single and group cyclones, most types of battery cyclones rotational movement purified gases are created by installing a swirling guide vane in each cyclone element.

Louvre-cyclone dust collection. The design of louvre-cyclone dust collection (Fig. 3) is the simplest inertial apparatus 1 with louvered grille 3. The blinds consist of overlapping rows of plates or rings with a gap of 2...3 mm, and the entire grille is given some taper to maintain a constant gas flow rate. The dusty flow passing through the grate at a speed of 15 m/s abruptly changes direction. Large particles of dust, hitting the inclined planes of the louvered grille, are reflected by inertia from the grille to the axis of the cone and are deposited. The gas, freed from large dust and passing through the grate, exits the apparatus.

Part of the gas flow (5.10%) sucked from the space in front of the louvre grille contains the main amount of fine dust and is sent to the cyclone 2, where it is cleared of fine dust under the action of centrifugal forces and then connected to the main flow of dusty gas. In such devices, the gas is approximately 60% free from dust, the particle size of which is 25 microns. Due to the relatively low efficiency and high hydraulic resistance, these devices are not widely used and are not mass-produced, but in in some cases(especially in combination with other dust collection devices) their use is completely justified.

When selecting and calculating cyclones, it is necessary to take into account such properties of the collected dust as abrasiveness and adhesion. To reduce abrasive wear, cyclones should be designed to operate at the smallest of acceptable values gas speeds. When collecting moderately clumped and highly clumped dust, do not use small-diameter cyclones (600-800 mm), which are prone to clogging.

When designing cyclones, especially for cleaning heated and humid gases, it is necessary to prevent the formation of water vapor from the gases in order to avoid clogging the cyclones with wet dust. To do this, it is necessary to maintain the temperature of the gases supplied for cleaning above the dew point temperature by at least 20. .25°; the housing must be covered with thermal insulation of a certain thickness.

When designing group cyclones, it is very important to evenly distribute the purified gases among the cyclones (provide symmetrical supply). If this condition is violated, due to different hydraulic resistance of individual cyclones, some gases will flow from one cyclone to another through dust outlets located in a common bunker.

In woodworking enterprises for cleaning ventilation air in pneumatic transport and aspiration systems, cyclones of Giprodrev, Giprodrevprom, Klaipeda OEKDM and UC type are used. Giprodrev cyclones effectively catch wood chips and large shavings.

Cyclones of the “C” type from Giprodrev and Klaipeda OEKDM are designed to collect shavings and sawdust from wood dust. They are installed only on the discharge side of the circuit and exhaust into the atmosphere. To avoid the capture of chips from the passing air flow in cyclones of the “C” type, a separator is mounted under the exhaust pipe.

To collect fine wood dust, as well as polyester dust in woodworking, cyclones of the UC-38 type, borrowed from the flour-grinding industry, are used; in their configuration, geometric relationships and performance indicators, the UC cyclones are similar to the conical cyclones of NIIOGaz.

The cyclone is one of the most common dust collection devices. However, with high efficiency Cyclones are capable of capturing dust only with a size of 15 - 20 microns or more.

The most widespread are the cyclones of the Research Institute of Gas Purification (NIIOgaz), shown in Fig. 1. Their distinctive feature is an inclined inlet pipe, a relatively short cylindrical part and exhaust pipe, as well as a small opening angle of the conical part.

The operation of the cyclone is based on the use of centrifugal forces that arise when the gas flow rotates inside the cyclone body. This rotation is achieved by introducing gas tangentially into the cyclone. As a result of the action of centrifugal forces, dust particles suspended in the gas flow are thrown onto the walls of the housing and fall out of the flow. The gas, freed from dust, continues to rotate, makes a 180° turn and exits the cyclone through an axially located exhaust pipe (Fig. 1).

Dust particles that have reached the walls of the housing, under the influence of a rotating flow moving in the axial direction and gravity forces, move towards the outlet of the housing and are removed from the cyclone. Due to the fact that the decisive factor determining the movement of dust is aerodynamic forces, and not gravity, cyclones can be positioned obliquely and even horizontally.

The slope of the inlet pipe and the screw-shaped top cover help direct the rotating gas flow downward, which reduces hydraulic resistance cyclone A snail is sometimes installed on the exhaust pipe of a cyclone, which spins up a rotating gas flow. The inclination of the inlet pipe and the cover, as well as the installation of the scroll, reduces the resistance of the cyclone.

A bunker is installed under the cyclone to collect collected dust. Dust should not accumulate in the conical part of the cyclone to avoid agitation and secondary entrainment into the exhaust pipe.

Basic rules for operating cyclones boil down to the following:

1. It is necessary to ensure that dust does not accumulate in the conical part of the cyclone. To collect it under the cyclone, a special bunker is provided.

2. Air leakage in the lower part of the cyclone is unacceptable. The dust collection bin must be sealed. Dust is discharged from the hopper through a pipe with a double shutter - a flashing light, adjusted so that the valves operate only alternately.

3. Standard cyclone designs can operate at gas temperatures no higher than 400° C and pressures (rarefactions) no more than 2.5 kPa

4. When running on gas high temperature cyclones are lined inside with fire-resistant tiles, and when the wall temperature is below the dew point temperature, it is covered with insulation on the outside.

5. The initial concentration for non-coalescing dusts in cyclones with a diameter of 800 mm or more is allowed up to 400 g/m3. For clumping dusts and smaller cyclones, the dust concentration should be 2 to 4 times lower.

6. The cyclone must operate with a constant gas load. In case of significant fluctuations in flow, groups of cyclones should be installed with the ability to turn off individual elements.

They allow you to remove unwanted or harmful suspended matter, remove sawmill or carpentry waste, and other small particles.

Transportation of solid particles is carried out by air flow. After delivery of the material to its destination it is necessary to remove them from the flow and stop moving, which is provided by special devices - cyclones. They perform the task of accumulating material; when a certain amount is reached, they are unloaded for further processing or disposal.

In some systems, cyclones are called dust collectors. They perform similar functions, only the fraction size of the transferred material is smaller, requiring greater density. Typically, in such systems only round channels are used, since rectangular ones create turbulence that contributes to the formation of dust accumulations.

Cyclones can serve both for the accumulation and removal of waste, and as product receivers. For example, at grain processing plants, elevators or similar departments, cyclones are receiving containers for products. At the same time, husks and other waste are also collected in cyclones installed on other lines. Such systems do not belong to general ventilation, being separate lines for transportation or dust removal. Combining such systems with ventilation is not practiced, since other equipment is required and the specifics of operation do not correspond to general ventilation technology.

There are areas where the use of cyclones is irrational. These include:

• textile industry. Small fibers and fluff particles are light in weight and scatter under any impact, which requires the use of a different collection technology
• steel production. The installations do not capture soot and allow many small particles to pass through.

The main users of cyclones are concentrated in woodworking, manufacturing building materials, metallurgy, grain processing enterprises.

Application and principle of operation of cyclones

The use of cyclones makes it possible removal of small waste, industrial waste with a loose texture. The devices have many advantages over other transportation methods, the main of which is ease of installation and maintenance, and the ability to use the entire workshop volume. Air ducts can be located at any point, the only requirement is that there are no sharp bends that contribute to the formation of congestion.

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A cyclone is a closed container in the form of a cone with the top facing down. Upper part container is connected to the outlet of the transport air duct, the lower part has an unloading hatch or dispenser hopper. An air stream carrying bulk waste or other material enters the cyclone. Due to a sharp expansion of the volume, the energy of the flow drops; the transported material, under the influence of gravity, sinks to the bottom of the container. Excess pressure generated inside the cyclone is released into the atmosphere through leaks top cover devices.

As the cyclone fills, it is unloaded through the lower hatch or dosing hopper. In installations that fill relatively slowly, hatches are usually installed, but for quickly filling cyclones, dosing hoppers are needed to quickly and mechanized way unload the container.

To create an air flow that entrains bulk material, special dust fans are used. They are radial-type structures with a small (usually 5-6) number of blades. This is a mandatory condition, otherwise debris particles will constantly get stuck between the blades of the impeller, which will make the operation of the fan significantly more difficult or stop altogether. A jammed impeller will cause motor failure, so only specialized equipment should be used.

Bag filters

One type of cyclone is bag filters. They are used in highly dusty production areas. The difference in the operation of bag filters and conventional cyclones lies in the specifics of the material being transferred. Dust particles have very low weight, which does not allow them to settle inside the container. Therefore, the flow from the workshops is supplied in the lower part of the housing, and not in the upper, as is done in cyclones. The dusty stream enters the housing, inside of which there are fabric bags with an open bottom. The air passing through them is cleaned and discharged through a pipe at the top of the device.

To separate solid particles from gases (air) that were used as a working fluid (for example, during pneumatic transport), and to avoid contamination environment, mechanical dry cleaning in cyclones, cleaning using fabric filters, as well as electrical and wet cleaning are used.

Centrifugal cyclones used for purifying gases with a dust content of 200-400 g/m 3, with minimum size besieged. particles 5-10 microns. The productivity of cyclones for the dust-air mixture, depending on their size, is 1500-15000 m 3 /h.

The operating principle of the cyclone is shown in diagram (IV). Dusty air is introduced into the upper cylindrical part of the housing tangentially. In a cyclone, the air moves in a downward spiral, for which a guide is provided - a fixed helical blade (or the cylinder cover is made along the helical surface). Under the influence of centrifugal forces, the particles are thrown towards the outer walls, slide down and are removed through a special gate through the cyclone. The purified air exits upward through the central pipe. The speed of the air mixture at the entrance to the cyclone is 15-25 m/s. The purification coefficient in centrifugal cyclones is 70-90%.

Small diameter cyclones provide better cleaning. Therefore, in order to achieve high degree cleaning and increase productivity, they are combined into groups (batteries). A diagram of such an installation is shown in the figure.

The air mixture enters through pipe 4 into distributor 3, from where it is supplied to cyclones 5. Purified air exits through pipes 7 into manifold 2 and is discharged through pipe 1 into the next cleaning cascade. The separated material settles in collection 6, from where it is removed through special gates. Technical characteristics cyclones is given in the table.

More complete cleaning gases are reached in fabric filters. The essence of gas purification in such filters is to pass gases through porous partitions on which small particles settle. Typically, partitions are made in the form of sleeves made of thick fabric. At gas temperatures above 100 °C, the sleeves are made of fiberglass. The bag filter diagram is shown below.

Contaminated air enters through pipe 1 into housing 2, in which hoses 3 are installed on special suspensions 4. Passing through the walls of the hoses, the gas is cleaned of dust that settles on them and is discharged through pipe 5. To ensure the operation of the filter, its hoses are periodically shaken with a special mechanism 6.

At the moment of shaking, the outlet pipelines 5 are closed by a valve 5, locked with the shaking mechanism. The material deposited in the collector 9 is fed by a screw 7 through the sluice gate 10 into the bunkers. To better clean the fabric, periodically blow through the filter clean air in the opposite direction.

The degree of purification in fabric filters reaches 96-98%, provided that dry gases are purified. The technical characteristics of bag filters are given in the table below. The most perfect is electric method gas purification.

The method is based on the ionization of particles suspended in a gas, when passing the latter through electric field high voltage. Particles that have received a charge move to the electrode, the charge of which is opposite in sign, and are deposited on it. Electrostatic precipitators capture particles up to 5 microns in size with a purification rate of up to 99%. Such filters work successfully to purify hot (up to 350°C) gases. Aerodynamic drag there is little difference in them from fabric ones. Energy consumption is about 0.3 kWh per 1000 m 3 of gas. Technical characteristics of electric precipitators are given in table. 20.

To create electric field A high voltage direct current (up to 75,000 V) is applied between the filter electrodes. Dust particles are electrolyzed in the electrostatic field created by the electrodes, are repelled from the corona electrode, and settle on electrode 1 connected to the housing.

The design of a horizontal electrostatic precipitator is shown below. The contaminated gas enters through the inlet distributor 1 into the filter measure 2, divided into two parallel sections. Each section contains three cascades of electrostatic precipitators through which the gas passes sequentially. Each cascade consists of several rows of precipitating mesh flat electrodes and corona electrodes consisting of rods 49 installed on insulators 5.

The collecting electrodes are periodically shaken by a cam mechanism 6 to free them from dust that has settled on them. The dust collected in the receivers 8 is removed through the gates 9. The purified gas is discharged through the collection manifold. The detailed calculation of the electrical and design parameters of electrostatic precipitators is specific and is carried out by specialized design organizations. When designing enterprises using these filters, they are selected according to catalog data; gov and reference books.

Equipment for wet cleaning contaminated gases are used for final purification of gases coming from rotary kilns and drying drums. Shown below vertical scrubber.

Contaminated gas flows through pipe 6 into the lower zone of the lined housing 1 ceramic tiles 2. Water is supplied to the upper zone of the scrubber through spray 3. The body contains 5 nozzles from wooden slats. The upper nozzle evenly distributes water over the cross section of the body, the middle one serves to catch dust, and the lower one distributes the flow of incoming gas.

Gas is introduced into the scrubber through pipe 6 at a speed of 18-20 m/s tangential to the housing. Relatively large particles, under the influence of centrifugal forces, are thrown towards the walls, wetted with water and flow down in the form of a film. The final capture of particles by water occurs when the gas flow passes through water curtain, formed over the entire cross section of the scrubber. To avoid water being carried out into collection 4, the gas velocity in the scrubber body should not exceed 6 m/s. The degree of purification in such a scrubber is 95-98%.

Below is the diagram foam dust collector, consisting of a body 3 divided in height by a grate 4. Water is supplied to the upper compartment on the grate through pipe 2 so that its layer on the grate is 20-30 mm. The dusty gas enters through pipe 1 and moves up through the grate towards the streams of water.

As a result of this movement, a layer of foam 120-180 mm thick is formed, in which dust particles are retained. The purified gas is collected in bell 5 and released into the atmosphere. Dust particles that form sludge with water are discharged through a collector 7 and partially through a side opening 6 along with the sludge. Foam dust collectors trap particles up to 3 microns in size. The speed of gas movement in the apparatus reaches 3.5 m/s. Water consumption is 0.5-0.8 m 3 per 1000 m 3 of gas.

The equipment discussed above is designed to remove dust from air and gases and, therefore, is equipment to protect the environment and improve human working conditions. However there are specific features during its operation, to which special attention should be paid.

In separators, cyclones and bag filters Compressed gas is used, which means there is a danger of explosion of these devices and pipelines if their operating modes are not observed. During operation, it is necessary to continuously monitor the incorrectness of control and protective instruments and devices (pressure gauges, safety valves etc.). Emergency control devices must be calibrated and sealed by a special service of the State Mining and Technical Supervision Service.

Only specially trained personnel with appropriate certificates are allowed to work with pressure equipment. IN electrical filters applies high voltage and exists increased danger defeats electric shock. Therefore, the filter must be installed in such a way as to prevent direct contact of personnel with live equipment.