Advantages:
Group cyclones Battery cyclones
D d
Types of waste water. Mechanical and physico-chemical methods of wastewater treatment.
Waste water is used water, as well as water that has passed through any contaminated area. Depending on the conditions of formation, wastewater is divided into household, atmospheric (or surface) and industrial.
Household - these are the drains of canteens, baths, laundries, toilets and others. Atmospheric wastewater is formed as a result of precipitation and flowing from the territories of enterprises. They are polluted with organic and mineral substances.
Three types of wastewater are generated on the territory of industrial enterprises: domestic, surface, and industrial.
Domestic wastewater from enterprises is generated during the operation of showers, toilets, laundries and canteens on its territory. The enterprise is not responsible for the quality of this type of wastewater and sends it to municipal treatment plants.
Surface wastewater from industrial enterprises is formed as a result of washing off impurities accumulating on roofs and walls with rain, melt and irrigation water. industrial buildings and within the enterprise. The main impurities of these waters are solid particles (sand, stone, shavings and sawdust, dust, soot, remains of plants and trees, etc.), oil products (oils, gasoline, kerosene). Each enterprise is responsible for the pollution of water bodies, so it is necessary to know the volume of wastewater of this type.
Industrial wastewater is generated as a result of the use of water in technological processes. Their number and composition are determined by the type of enterprise, its capacity, the types of technological processes used, the composition of the initial fresh water and local conditions, the scheme of water supply and sanitation of industrial enterprises.
All applied methods can be divided into mechanical, physico-chemical, chemical and biochemical. Mechanical methods are used to treat wastewater from coarse impurities (for example, sedimentation, filtering and filtration, centrifugal filtration). Physico-chemical methods are used to purify wastewater from fine impurities, from mineral and organic impurities (for example, coagulation, flocculation, ion exchange, sorption, osmosis, extraction, etc.). Chemical methods include neutralization, oxidation and reduction, reagent cleaning methods used to remove heavy metal ions. The biochemical method is used to purify household and industrial wastewater from many dissolved organic and some inorganic (hydrogen sulfide, sulfides, nitrites, ammonia) substances. The purification process is based on the ability of microorganisms to use these substances for nutrition in the process of life - organic substances for microorganisms are a source of carbon.
The use of physicochemical methods has a number of advantages.
1. The possibility of removing toxic, biochemically non-oxidizable organic contaminants from wastewater.
2. Achieving a deeper and more stable degree of cleaning compared to mechanical.
3. Smaller structures (compared to mechanical cleaning).
4. Less sensitivity to load changes.
5. Possibility of full automation.
6. Deeper knowledge of the kinetics of processes occurring during physical and chemical treatment, as well as issues of modeling, mathematical description and optimization, which is important for right choice and equipment calculation.
7. Methods are not related to the control of the activity of living microorganisms, in contrast to biochemical purification.
8. Possibility of recovery of various substances.
The principle of operation of centrifugal cyclones. Cyclone designs
Advantages: absence of moving particles in the device; reliable functioning at high temperatures gases; the ability to capture abrasive materials; dust is captured in a dry form; the hydraulic resistance of the devices practically does not change during operation, which is important when choosing ventilation equipment; technologically easy to manufacture; an increase in the dust content of gases does not lead to a decrease in the fractional cleaning efficiency.
Cyclones are distinguished by the method of supplying the purified gas to the apparatus: gas supply to the apparatus in a spiral; tangential gas supply; helical; gas supply through the "socket" with gas return; gas supply through a "socket" with a direct-flow outlet.
Structurally, they also distinguish: cylindrical and conical; group; battery. Group cyclones are used to purify gases of large volumes, as well as to increase the degree of purification. Battery cyclones are used to clean flue gases of thermal power plants, industrial boilers that burn solid fuels.
The principle of operation and the device of cyclones
The dusty gas flow is introduced into the upper part of the cyclone body, which is a cylinder (diameter D), ending in a cone at the bottom. The gas inlet pipe to the cyclone of rectangular shape must be placed tangentially to the circumference of the cylindrical part of the cyclone. The gases leave the apparatus through a round pipe (diameter d) located along the axis of the cyclone. After entering the cyclone, the gases move from top to bottom, rotating first in the annular space between the outer cylindrical surface of the cyclone and the central outlet pipe, and then in the main body of the cyclone, forming an external rotating vortex. In this case, centrifugal forces develop, under the influence of which dust particles suspended in a rotating gas flow are thrown to the walls of the cyclone body, both cylindrical and conical parts. At this stage, the process of dust settling is carried out due to centrifugal forces.
At the second stage, at the conical wall of the cyclone, the gas flow begins to be affected by the pressure difference between the inlet and outlet nozzles of the cyclone, the compressive force of which significantly exceeds the centrifugal forces. The concentration of particles in the gas stream reaches the limit load. As a result, dust particles are released from the main flow and their further sedimentation occurs due to the secondary near-wall vortex, which carries the main part of the dust into the hopper. The purified main gas flow, freed from dust, begins to turn due to the pressure drop and move upwards to the outlet pipe, forming an internal rotating vortex.
The most versatile and commonly used cyclones. Designed to separate from the gaseous medium of suspended particles of dry dust formed in various grinding and crushing plants, during the transportation of bulk materials, as well as fly ash. For fibrous and sticky dust, for cleaning a gaseous medium in which there is a droplet-liquid phase or vapor condensation is possible, these cyclones should not be used. Cyclone TsN-15 is more productive.
Cyclone STsN-50 One of the best NIIOGAZ cyclones. Cyclones STsN-50 are used to clean air or gases from fine dust (more than 10 microns) and medium dispersion, as well as abrasive dust in various industries. Increased inlet and outlet pipes compared to STsN-40 allowed the developer to reduce the cyclone resistance and increase the productivity of the STsN-50 cyclone. At the same time, the overall dimensions of the STsN-50 cyclone became closer to the TsN-15 of similar capacity.
Cyclone TsN-24 has a high throughput with a low level of purification. The use of these cyclones is justified as a preliminary purification stage, as a cyclone-unloader, as well as for gas purification from dust with an average diameter of more than 20 microns.
Cyclone STsN-40 is designed for effective purification of gases and aspiration air from fine and medium-dispersed dust. It has the highest degree of purification in comparison with cyclones TsN-15, SK-TsN-34 and UTs-38.
Cyclone SDK-TsN-33 it is used to clean gases from fine dust, with an average diameter of 5-6 microns, as well as for high requirements to the quality of cleaning. Able to provide a high degree of purification at a relatively low gas flow rate at the cyclone inlet.
Cyclone SK-TSN-34 designed to capture solid particles of auxiliary systems for the production of technical carbon, catalytic cracking of petroleum products, butane dehydrogenation. The intended purpose of these cyclones is soot production.
Cyclone SK-TsN-34M used to trap dusts with high abrasiveness of particles or their high stickiness. The most effective of the TsN series. However, the pressure loss in these cyclones is approximately 2 times greater than in the SDK-TsN-33, SK-TsN-34 cyclones.
Cyclones for removal of wood waste
JECDM Used in pneumatic conveying systems wood waste low dust content: wood chips, bark, twisted shavings, wet sawdust, heavy dust. Compared to other common cyclones, they have the lowest coefficient of hydraulic resistance, which means the lowest energy consumption. They are mainly installed on the discharge section of the system (after the dust fan).CDO are intended for use in pneumatic transport systems for crushed wood waste: wood chips, bark, sawdust and shavings. The main advantages are high productivity with a low coefficient of hydraulic resistance and relatively small dimensions. According to its characteristics, it is close to type K cyclones (OEKDM), but more compact.
CDO-V variant of DDO execution: they have a snail-tangential swirler and are intended for installation in aspiration systems upstream of the fan. They are used in systems of pneumatic transport of large fractions of wood waste or as a cyclone-unloader of various bulk materials.
UTs and UTs-38 They are used to clean technological emissions from woodworking industries from non-sticking, non-fibrous dusts, as well as mixtures of dry sawdust, shavings and grinding dust. Widely used in furniture factories. They are installed both on the discharge and on the suction side of the fan. When installed on the suction side of the fan, a volute must be added. UTs-38 differ in a more developed conical part and are designed to capture finer bulk materials that are subject to easy entrainment.
Cyclone type C (Giprodrevprom) serves to catch shavings, sawdust and wood dust. A special feature is the presence of a separator operating on the principle of a louvered dust collector with a screw inlet, which contributes to additional. unwinding the air flow and increasing the degree of cleaning.
Cyclone Giprodrev provides rough air purification from sawdust, shavings, wood waste and dust at woodworking enterprises. Possesses low aerodynamic resistance.
Cyclone LTA It is used to clean air during transportation from machine tools and sawmills of large particles (wood chips, shavings) and wet small particles (sawdust) or in technological process for separating large chips.
Cyclones for the flour industry
Cyclone TsOL designed to capture large and medium (more than 120 microns) grain dust in aspiration plants of elevators and flour mills.Cyclone TsR and TsRK (shortened) are designed to capture large fractions of dust at grain processing enterprises, where it is required to purify the air from large fractions during transportation and loading of products without significant energy costs.
Cyclone OTI designed to capture a mixture of grain waste in the pneumatic transport system at grain processing and food enterprises. Not suitable for fibrous and sticky dust. They are installed in groups of 2-8 cyclones, which significantly increases the dust collection coefficient. Resistant to input speed changes up to ±35%, which is important for variable speed systems.
Cyclone UCM-38 designed to capture flour dust in grinding and peeling departments of flour and cereal factories. As a swirler, a snail of a spiral-helical shape is used. This made it possible, with the same efficiency, to increase productivity and reduce the aerodynamic drag of the UCM cyclone compared to the UTS cyclone.
Cyclone TsVV high-performance cyclone unloader with a built-in dust fan is designed to clean the air from dust in pneumatic transport and aspiration systems at woodworking and grain processing enterprises. Air dust content up to 2 kg is allowed. per m3.
Cyclone BTSSH is designed to clean the air from dust in pneumatic transport and aspiration systems at grain storage and processing enterprises, food industry and agriculture enterprises.
Reverse cone cyclones for capturing abrasive and sticky dusts
ZOK cyclones designed to clean ventilation emissions from dust with increased abrasive properties. It is allowed to use cyclones with sticking dusts such as soot and talc. They are used in shops of mechanical processing of metal, in tool-grinding and peeling installations.Adjustable cyclone RC- Designed to capture sticky and oily dusts. It is equipped with a special control device that allows you to adjust the air mode of the device, which helps prevent the removal of large particles and carry out dust coagulation.
Cyclone CM- improved design of the CSC cyclone - designed for cleaning from granular, fibrous dust prone to sticking together; waste of crushed materials of light, food, printing industry; from dust generated during the processing of agricultural products; heavy abrasive dusts.
Cyclone RISI Suitable for all types of fibrous and highly sticky dust, polishing dust and paint waste.
Cyclones and swirl cleaners for dry dust
CDW is designed to clean waste air removed by aspiration and pneumatic transport systems from process equipment in various industries. Sandy, clay, cement, silicate, asbestos and other types of dust.VZP-M differs from VZP in a higher efficiency of catching fine dust, as well as fibrous and sticky dust. In the VZP-M cyclone, the upper swirler is snail.
Dry cyclone type SIOT Designed for coarse and medium cleaning of air and gases from non-sticking non-fibrous dust. The design of the SIOT cyclone is characterized by the absence of a cylindrical part of the body and the triangular shape of the inlet pipe. This cyclone is not inferior in efficiency to the cyclone TsN-15
Cyclone SIOT-M- a modernized version of the SIOT cyclone. A number of design changes made it possible to improve the flow structure and increase the degree of purification, which made it possible to add three b O larger sizes.
V cyclone SIOT-M1 to increase the degree of cleaning between the body and the hopper, an insert-twist is installed (as in VZP dust collectors). The main dusty flow enters the upper part of the cyclone, and the additional flow is fed into the lower part of the cyclone.
Cyclone LIOT It is used for coarse and medium air purification from dry, non-sticky, non-fibrous dust.
For better distribution of gas with dust and for dust removal, a battery cyclone is widely used in practice. Such an apparatus is a cyclone elements that are connected in parallel and have a common body, a collection hopper, as well as a common gas supply and discharge.
In battery cyclones (multicyclones), gas movement is achieved by installing a swirling element in the form of a socket or screw in each part of the apparatus, and not by a tangential gas supply. Due to this, the performance of a battery cyclone will be much greater than that of a conventional cyclone of the same size.
The most popular types of cyclone element can be seen in the figures.
The “screw” element has the least hydraulic resistance and is practically not prone to clogging with dust.
The deposition of dust in the individual elements of such a cyclone occurs in the same way as in an ordinary cyclone. The most commonly used cyclone elements are 100, 150 or 250 mm in diameter. In such devices, a dusty gas velocity of about 4 m/s can be achieved. Such devices have a high rate of dust deposition. At the same time, they have a small size and hydraulic resistance. That is, if we compare battery cyclones with single or group ones, then with the same size the former are more efficient.
The design and principle of operation of the battery cyclone (multicyclone)
The polluted gas is fed into the gas distribution chamber, which is limited by tube sheets. The cyclone elements are hermetically fixed in the tube sheets. After the gas is purified, it is discharged through the exhaust pipes of the elements into the common chamber. The separated dust particles accumulate in the conical bottom of the cyclone. Cyclone elements of this design have a small diameter. Gas enters them from above, and not tangentially. The rotational movement of the gas flow is transmitted through a special screw or rosettes equipped with inclined blades.
The high-quality operation of a battery cyclone installation is ensured due to the identity of its elements and equal operating conditions.
The general body of the multicyclone includes cyclone elements. The elements are hermetically installed in the tube sheets. The source gas enters the gas distribution chamber through the fitting and is distributed over the cyclone elements, fills the annular space between the element body and the branch pipe for removing the purified gas. Bladed devices are located in the annular space, causing the gas flow to rotate. Dust particles are thrown to the walls of the cyclone element, move downward in a spiral and enter the hopper common to all elements. The purified gas from each element is discharged through a pipe into a common chamber, and from there - out through the top fitting.
battery cyclone
As a rule, single cyclones have a diameter of 40-1000 mm, and cyclone elements - 40-250 mm.
Battery cyclones are small-diameter cyclones connected in parallel. Such devices capture dust better, because. with a small radius of the cyclone, the centrifugal force increases significantly.
Battery cyclones are capable of operating with a variable load, i.e. if necessary, you can turn on or off individual battery cells.
The pipe is equipped with external helical vanes, which transfer the gas flow in a spiral motion. The gas is fed into the housing from above, then passes over the surface of the screw in the annular space (between the outer surface of the pipe and the inner surface of the housing). Solid particles linger on the walls of the housing, after which they fall into the lower conical part and enter the battery hopper.
The structural elements of the battery cyclone are located vertically, in parallel rows in a rectangular body. The chamber is equipped with two gratings, in the holes of which the elements are installed. The gas to be purified is fed through a branch pipe into the space between the gratings and distributed over individual elements. After purification, the gas enters the space above the upper grate and is discharged through the side pipe. Solid particles fall into the conical bottom. The structural elements of the battery are made of cast iron, and the gratings are made of sheet steel. Such devices are capable of purifying gas over a wide temperature range.
Dust-cleaning cyclone is an equipment that is used in some models of vacuum cleaners and industry for cleaning liquids and gases from suspended particles. The principle of operation, which uses a cyclone, is inertial, while centrifugal and gravitational forces are applied. Such dust collectors make up the most massive group among other dust collectors and are used today in all areas of industry. The collected dust is usually recycled in the future.
The purpose of the cyclone
Cyclone for air purification from dust can be used in transport. This includes trucks of the type KamAZ and MAZ. With this equipment, it is possible to carry out preliminary effective cleaning air, which in the next stage enters the internal combustion engine. After that, a complete cleaning takes place, which is carried out in an inertial oil air filter. It may also be dry.
The equipment is also used in the conditions of elevators, where grain products are involved in a complex of operations associated with transportation, reloading, storage and processing. Huge masses of mineral and organic dust particles are released into the air at each stage of the process. They contaminate fine fractions, which are explosive and flammable.
Main tasks
As one of the main key tasks of the enterprises of the grain processing industry are the prevention of dust emission and the reduction of the concentration of grain dust. To solve such problems, grain processing enterprises use dedusting ventilation systems which include aspiration and ventilation equipment.
The cyclone for air purification from dust in this case is used for industrial air purification in the processing of grain materials and grain. Such equipment is characterized by ease of maintenance and simple design. It is inexpensive, characterized by high performance and low resistance. That is why such installations are today one of the most common among other types of equipment for mechanical dust removal.
Principle of operation
The cyclone for cleaning the air from dust works quite well. simple principle. It lies in the fact that the streams of polluted gas enter the apparatus through a pipe in the upper part. A gas flow is formed in the equipment, which constantly rotates. It is directed downward and rushes to the conical part of the equipment.
Inertia, which is the removal of particles from the flow, settling on the walls of the device. They are captured by the secondary flow and carried away to the lower part. The contaminants enter the outlet in the hopper where the dust is collected. The gas stream is cleaned of contaminants, it moves from the bottom up and is discharged outside through the exhaust pipe.
What else you need to know about the principle of operation
The cyclone for cleaning air from dust, the purpose of which was described above, provides centrifugal acceleration, which is several thousand times greater than the acceleration of gravity. This causes even the smallest dust particles to remain on the walls and not be carried away by the gas. The collected dust moves in a spiral, and fresh air changes direction, entering the cyclone zone. The degree in this case reaches 90%. The final value will depend on the size of the equipment, the speed and properties of the dust particles.
If the diameter of the cyclone is smaller, then the efficiency of collecting debris will increase, the flow rate will increase. If we consider the cyclone together with the elevator equipment, then dust collectors can increase the reliability of the complex, reducing the risk of fire hazard. These devices reduce the likelihood of occupational diseases for people working in storage facilities. Therefore, at any elevator, the cyclone installation acts as one of the necessary links in the technological chain.
Description of the cyclone brand JET CDC-2200 10001056T
The mentioned cyclone for air purification from dust, the characteristics of which will be presented below, has a cost of 132,000 rubles. This equipment represents exhaust unit, which has found application in the conditions of small industries and private workshops. The unit can be used in conjunction with woodworking machines and for collecting debris from the floor when operating small-scale wood production equipment.
Additional advantage
The design has a garbage container, which is made of metal, it is almost not subject to mechanical damage. The technology used by the cyclone guarantees fast and high-quality air purification and allows sorting waste into fractions. Small particles enter special containers, while the chips are sent to a metal hopper.
Specifications of the model and some of its positive features
The above model of the cyclone consumes air in the amount of 36 m 3 /min. The kit comes with one dust bag. The diameter of the nozzle of the vacuum cleaner is 100 mm. Equipment dimensions are 1200x700x1800 mm. The power of the device is equivalent to 2600 watts. The unit has two suction openings.
Dust bags are designed for 105 liters of volume. Such cyclones for air purification of wood dust weigh quite a lot. For example, the mass of the described model is 88 kg. Before purchasing such a device, it is important to pay attention to some features, among them:
- long service life;
- convenient transportation;
- emergency shutdown;
- thoughtful design;
- mobility.
As for the long service life, it is provided by a variety of stiffeners that contribute to the efficient cooling of the motor during operation. This increases the service life and eliminates overheating. The unit is equipped with transport loops that allow you to move the equipment using a lifting mechanism.
The main types of cyclones
The cyclone for cleaning air from dust, the types of which will be presented below, is equipment similar to hydrocyclones. These designs have only some differences, expressed in the shape of the body. Cyclones can be classified into direct-flow and counter-flow. In the first case, the gas is discharged along one axis; such a system is not as efficient as counterflow.
Cyclones are also subdivided according to the shape of the hull, they can be:
- conical;
- cylindrical-conical;
- cylindrical.
A cyclone for cleaning air from dust, the manufacture of which can be done independently, is also divided into elements. This makes it possible to single out helical, tangential and spiral designs of cyclones. Cylinders are also subdivided according to the direction of twisting: they can be right or left.
Cyclone calculation
Calculation of a cyclone for cleaning air from dust can be carried out on the basis of determining the centrifugal force. In this case, the formula C \u003d (m ω²) / r should be used, where the mass is denoted by the letter m, the speed of rotation of the body is ω, while the radius of rotation is denoted by the letter r. The ratio of the acceleration of the centrifugal force to the acceleration of gravity corresponds to the ratio of the magnitude of the centrifugal force to the force of the weight of the body. This parameter is the main one, and it characterizes centrifugal apparatuses.
Making a cyclone with your own hands
You can easily make a cyclone for cleaning the air from dust with your own hands. This will allow you to establish furniture production in your own workshop. At the same time, workers will not be exposed to the dangerous effects of the smallest wood dust that they would have to inhale. At the first stage, a centrifugal fan in the form of a snail is made. The body can be made from alucobond and the body covers can be made from 20mm plywood.
Via manual router grooves are made in the covers, the diameter of which will be 3 mm. The body of the snail is installed in the groove, the whole structure is tightened with bolts. At the next stage, a snail fan is made from alucobond, for this two circles are cut with a milling cutter, grooves are made into them, into which the blades are installed. They are glued with a hot glue gun. This will give you a drum that looks like a squirrel wheel.
A cyclone for cleaning air from dust, which can be produced independently, will have a fairly strong and lightweight impeller with precise geometry. It is put on the axis of the engine. One with a power of 0.55 kW is suitable. For the manufacture of the case, you will need 20 mm plywood, on the surface of which, using a compass, you need to draw the circumference of the base. The upper body in the form of a cylinder is bent from the roofing sheet. On the base, fastening is carried out with self-tapping screws, the joints are glued with double-sided tape. The sheet is pulled together with rivets. The lower conical part is made according to the same principle.
Work methodology
The manufacture of a cyclone at the next stage involves installation in a cylinder. They should be glued with hot glue. WITH inside cylinder suction pipe must be given a rectangular shape. For this, it is heated with a hairdryer, and then a wooden mandrel is inserted into it, after which it is cooled. The air filter housing is bent according to the same principle. The filter can be borrowed from KamAZ, because it has an impressive filter curtain area.
Now you can connect the lower housing and the upper cylinder by screwing the volute on top. Air filter secured with polypropylene fittings. The whole structure is assembled, and a plastic barrel is installed for sawdust. A transparent corrugated pipe must be used to connect to the lower cone, this will allow the master to see the filling level. The unit at the last stage must be tested by connecting it, for example, to a planer. After all, most of the chips are formed from this equipment.
Details Created on 08/10/2012 03:57 PM Updated on 08/13/2012 04:49 PM Author: AdminTo isolate solid particles from gases (air), which were used as a working fluid (for example, in pneumatic transport), and to avoid environmental pollution, mechanical dry cleaning in cyclones, cleaning with fabric filters, as well as electric and wet cleaning are used. .
Centrifugal cyclones used for gas cleaning at dust content of 200-400 g/m3, at minimum size besieged. particles 5-10 microns. The productivity of cyclones in dusty air mixture, depending on their size, is 1500-15000 m 3 /h.
The principle of operation of the cyclone is shown in the scheme (IV). Dusty air is introduced into the upper cylindrical part of the housing tangentially. In the 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 action of centrifugal forces, the particles are thrown to the outer walls, slide down and are removed through a special gate through the cyclone. The purified air exits up the central pipe. The speed of the air mixture at the entrance to the cyclone is 15-25 m/s. The purification factor in centrifugal cyclones is 70-90%.
Small diameter cyclones provide better cleaning. Therefore, in order to achieve a high degree of purification 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 fed into cyclones 5. The purified air exits through tubes 7 into collector 2 and is discharged through pipe 1 into the next purification cascade. The selected material settles in the collection 6, from where it is removed through special gates. The technical characteristics of the cyclones are given in the table.
A more complete purification of gases is achieved in cloth filterspax. The essence of gas purification in such filters is the passage of gases through porous partitions, on which small particles settle. Usually partitions are made in the form of sleeves of thick fabric. At gas temperatures above 100 ° C, the sleeves are made of fiberglass. The bag filter diagram is shown below.
Polluted air enters through pipe 1 into housing 2, in which sleeves 3 are installed on special hangers 4. Passing through the walls of the sleeves, the gas is cleaned of dust that settles on them and is removed through pipe 5. To ensure the operation of the filter, its sleeves are periodically shaken with a special mechanism 6.
At the moment of shaking, the outlet pipelines 5 are closed by a damper 5 locked with the shaking mechanism. The material deposited in the collection 9 is fed by the screw 7 than the sluice gate 10 into the bunkers. To better clean the fabric, clean air is periodically blown through the filter in the opposite direction.
The degree of purification in cloth filters reaches 96-98%, provided that dry gases are purified. Technical characteristics of bag filters are given in the table below. The most perfect is the electric method of gas purification.
The method is based on the ionization of particles suspended in a gas, when the latter is passed through a high voltage electric field. 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 with a degree of purification up to 99%. Such filters successfully work on purification of hot (up to 350°C) gases. The aerodynamic resistance in them is small, how they differ from cloth ones. The energy consumption is about 0.3 kWh per 1000 m 3 of gas. The technical characteristics of electrostatic precipitators are given in Table. twenty.
To create an electric field between the electrodes of the filter, a high-voltage direct current (up to 75,000 V) is used. Dust particles are electrolyzed in an electrostatic field with given electrodes, repelled from the corona electrode, and deposited on electrode 1 connected to the body.
The device of a horizontal electrostatic precipitator is shown below. The polluted gas enters through the inlet distributor 1 to the filter chamber 2, divided into two parallel sections. In each section, three cascades of an electrostatic precipitator are mounted, through which the gas passes in series. Each cascade consists of several rows of precipitating grid flat electrodes and corona electrodes 49 consisting of rods mounted on insulators 5.
The collecting electrodes are periodically shaken by a cam mechanism 6 to free them from the 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. A 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 the catalog data; gov and reference books.
Equipment for wet cleaning polluted gases are used for the final purification of exhaust gases from rotary kilns and drying drums. Below is shown vertical scrubber.
Contaminated gas through pipe 6 enters the lower zone of the body 1 lined ceramic tiles 2. Water is supplied to the upper zone of the scrubber through the sprinkler 3. Nozzles 5 of wooden slats. The upper nozzle evenly distributes water over the section of the housing, the middle nozzle serves to trap dust, and the lower nozzle distributes the flow of incoming gas.
The gas is introduced into the scrubber through pipe 6 at a speed of 18-20 m/s tangentially to the body. Relatively large particles under the action of centrifugal forces are thrown to the walls, wetted with water and flow down in the form of a film. The final capture of particles by water is carried out when the gas flow passes through the water curtain formed over the entire cross section of the scrubber. In order to avoid the removal of water into the collector 4, the velocity of the gas in the scrubber housing should not exceed 6 m/s. The degree of purification in such a scrubber is 95-98%.
The diagram below is shown foam dust collector, consisting of a body 3 divided in height by a grate 4. Water is supplied to the grate through the branch pipe 2 in the upper compartment 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 water jets.
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 the cap 5 and discharged into the atmosphere. Dust particles that form sludge with water are discharged through the collector 7 and partially through the side hole 6 together with the sludge. Foam dust collectors trap particles up to 3 microns in size. The speed of movement of gases 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 for dedusting air and gases and, therefore, is equipment for protecting the environment and improving human working conditions. but during its operation, there are specific features to which special attention should be paid.
Separators, cyclones and bag filters use compressed gas, which means that there is a risk of explosion of these devices and lines, if their operating modes are not observed. During operation, it is necessary to continuously monitor the incorrectness of control and safety devices and devices (pressure gauges, safety valves, etc.). Control and emergency devices must be calibrated and sealed by a special service of Gosgortekhnadzor.
Only specially trained personnel with appropriate certificates are allowed to work with pressure equipment. Electrical filters use high voltage and there is an increased risk of electric shock. Therefore, the filter must be installed in such a way as to exclude direct contact of personnel with live equipment.
