What are the common dust removal equipment and technologies?

The working principle of this dust collector is that when the dusty gas passes through the expanded part of the pipeline (gravity settling chamber), the flow velocity is greatly reduced, and the larger dust particles settle down under the action of gravity. In order to prevent the air vortex from taking away the settled dust particles, baffles are usually added in the settling chamber. The air velocity passing through the settling chamber shall not be greater than? 3 m/s, the pressure loss is generally 10 ~ 20 mm water column, which can capture dust particles with particle size greater than 50 microns. Gravity dust collectors can be divided into dry type and wet type, with dry dust removal efficiency of 40-60% and wet dust removal efficiency of 60-80%. Gravity dust collector is suitable for pre-purification of dusty gas. In order to improve the dust removal efficiency, the height of settling chamber can be reduced or multi-layer settling chamber can be set.

Inertia vacuum cleaner

How does it work? The dusty airflow impacts the baffle or filter layer. The airflow suddenly turned. Dust particles are separated from the airflow under the action of inertial force. ? There are two types: collision type and rotational type. 1 and 2 are collision type, 3 and 4 are rotary type, and 4 is also called louver type). Inertial force dust collector is suitable for collecting dust particles with particle size larger than 10 micron, but it is not suitable for caking and fibrous dust because of easy blockage. Its pressure loss varies with the structure, generally 30 ~ 70 mm water column. The dust removal efficiency is 50 ~ 70%.

Centrifugal vacuum cleaner

It is a device to remove dust particles in airflow by using centrifugal force generated by airflow in vortex motion. ? The most commonly used is cyclone dust collector. ? When the cyclone dust collector works, the airflow enters the dust collector from the upper part along the tangential direction and rotates in it. Under the action of centrifugal force, dust particles are thrown to the inner wall of the cylindrical part of the dust collector and fall into the dust collection chamber. Centrifugal dust collector was used in 1885, and it has developed into many types, such as axial airflow introduction, axial dust outlet configuration or peripheral configuration. Its characteristics are simple structure, low cost, no moving parts, and the pressure loss is generally 40 ~ 150 mm water column, which is suitable for removing dust particles larger than 5 microns. The dust removal efficiency of the protective film is about 70 ~ 90%. Multi-tube cyclone (referred to as multi-tube cyclone) is composed of multiple single-tube cyclone plastic combustion plates.

Several cyclone separators with smaller diameters can be connected in parallel. Cyclone separators can also be connected in series. The former stage adopts cyclone dust collector with larger diameter. The diameter of the rear stage is smaller. ? The parallel multi-tube dust collector can be made into vertical and vertical. Horizontal and inclined structures. ? The multi-tube dust collector produced in China has two cylinder diameters of 150 and 250 mm, with 9 tubes, 12 tubes and 16 tubes. Multi-tube dust collector can remove dust particles with particle size larger than 3 microns, with pressure loss of 50 ~ 200mm water column and dust removal efficiency of 85 ~ 95%.

Washing dust collector

A device for purifying dusty gas by washing with water. ? There are the following types: gravity spray dust collector, also known as spray tower or washing tower. ? When the dust-containing gas passes through the droplet space of the spray liquid, due to the collision, interception and condensation between dust particles and droplets. Larger dust particles are precipitated by gravity. And is discharged from the bottom of the tower together with the washing liquid. ? In order to ensure uniform airflow in the tower, porous distribution plates or packed beds are often used. ? The pressure loss of gravity spray dust collector is less than? 25 mm water column, usually used to remove dust particles with particle size greater than 50 microns. This plastic combustion plate has the characteristics of simple structure, small resistance and convenient operation. But it consumes a lot of water, occupies a large area and is inefficient.

cyclone scrubber

The particle size of this vacuum cleaner is smaller than? 5 micron dust particles, suitable for occasions with large gas volume and high dust concentration. Commonly used cyclone water film dust collector, Rotary water film dust collector and central spraying cyclone dust collector. ? The cyclone water film dust collector sprays water mist to the dust collector wall along the tangential direction through the nozzle on the upper part of the dust collector cylinder. Form a thin flowing water film on the wall. The dusty gas flows out from the lower cylinder, and the inlet velocity is about? 15 ~ 22 m/s enters tangentially, rotates and rises, and dust particles are thrown to the wall by centrifugal force, attached to the water film and discharged with the water flow. The pressure loss of airflow is 50 ~ 75 mm water column, and the dust removal efficiency can reach 90 ~ 95%.

Horizontal cyclone water film dust collector

Also known as drum dust collector or rotary dust collector. ? After entering the dust collector, the airflow rotates along the spiral channel. Under the action of centrifugal force, dust particles are thrown to the cylinder wall. ? The airflow impacts the water surface in the water tank at high speed. Dust particles fall into the water. The impact of airflow on the water surface leads to the collision between water droplets and dust particles. It can also capture dust particles. ? The airflow carrying water droplets continues to rotate. Water droplets were thrown at the wall. Form a water film. Catch dust particles falling on the wall. ? What is air pressure loss? 80 ~ 100 mm water column.

Central spray cyclone dust collector

The center is provided with a spray porous tube. The dusty airflow is introduced tangentially from the lower part. Dust particles are thrown to the wall by centrifugal force. Due to the collision between water droplets and dust particles and the adhesion of water film on the equipment wall to dust particles, dust particles are removed. What is air pressure loss? 50 ~ 200mm water column. ? Is it suitable for less than? 0.5 micron dust particles, its dust removal efficiency is 95 ~ 98%.

Diaphragm pump dust collector

Depending on the kinetic energy of the airflow itself, the dust collector hits the liquid surface and stirs up water droplets and spray. ? For example, an impact water bath dust collector, the dusty airflow is ejected from the nozzle at a high speed. Change direction after entering the water. Large particles of dust are captured by water. ? The airflow continues to flow through the water layer, arousing a lot of spray, foam and droplets, and dust particles are captured again, and the dust removal efficiency can reach 80 ~ 95%. The pressure loss is about 100 ~ 150 mm water column. In addition, there are pulse and double-blade pulse dust removal devices made according to the same working principle.

Foam dust collector

Also known as foam scrubber, or simply foam tower. There are one or several porous sieve plates in the tower, and the washing liquid flows to the tray to maintain a certain liquid layer height. The dusty airflow is introduced from the lower part of the tower. Uniformly passes through the small holes on the tower plate and is dispersed in the liquid flow. At the same time, a lot of bubbles were produced. Increase the surface area of gas-liquid two-phase contact. So that dust particles are captured by the liquid. ? Dust removal efficiency mainly depends on the thickness of foam layer. Foam layer thickness? When 30 mm, the dust removal efficiency is 95 ~ 99%; When the thickness of foam layer is 1.20 mm, the dust removal efficiency can reach above 99.5%. The air pressure loss is 50 ~ 80mm water column.

Jet washing dust collector

The working principle of this kind of dust collector is to inject water into the ejector at high pressure (3.5 ~ 7 kgf/cm2) to inhale dusty gas, so that the dust particles in the airflow collide with water droplets and are captured. ? Then the mixture of water droplets and gas enters the precipitation chamber. Water droplets and dust particles are separated from the airflow. Achieve the purpose of dust removal. ? Is this vacuum cleaner suitable for removing particle size? The dust removal efficiency of dust particles above 0.5 micron is about 90%. Because of the large water consumption and high operating cost, it is not suitable for treating a large number of dusty gases.

Packed bed scrubber

Also known as packed tower. ? Packing layer wetted by spray liquid. There is a big wet surface. ? When the dusty airflow passes through the packing layer, the dust particles are captured and removed when they hit the surface of the wet packing. ? Can this vacuum cleaner remove particles? The dust removal efficiency of dust particles above 3 microns is about 90%. The air pressure loss is 1.5 ~ 50 mm water column. There are vertical and horizontal packed bed scrubbers, single packing and multi-layer packing, fixed bed, moving bed and fluidized bed, horizontal flow and cross flow, etc.

Venturi dust collector

Also known as venturi dust collector, it consists of venturi condenser and demister. ? The condenser consists of a contraction tube. Throat and diffuser. ? The velocity of dusty gas increases after it enters the contraction tube, and reaches the maximum when it enters the throat. When the washing liquid is added from the contraction tube or throat, the relative velocity between gas and liquid is very high, the droplets are atomized under the high-speed airflow, the gas humidity reaches saturation, and the dust particles are wetted by water. Violent collision and condensation occur between dust particles and fog droplets or between dust particles and dust particles. In the diffusion tube, the air speed decreases, the pressure increases, and the condensation with dust particles as condensation nuclei accelerates, and it condenses into dust-containing droplets with larger particle size, which is easy to be trapped.

Is Venturi dust collector suitable for removing particle size? 0. 1 ~ 100 micron dust particles have a dust removal efficiency of 80 ~ 95% and a pressure loss of 300 ~ 800 mm water column. If the venturi tube is equipped with a device to adjust the throat diameter, the dust removal efficiency will not decrease when the gas flow rate changes. Venturi structure has many forms, which can be divided into round and square according to the cross-sectional shape. According to the throat structure, it can be divided into adjustable throat diameter and fixed throat diameter; According to the atomization mode of liquid, it can be divided into pre-atomization and non-pre-atomization. Since the early 1970s, some factories have used steam and hot water wet dust collectors, and the dust removal efficiency can be improved to 99.9%, and the waste heat of factories can be utilized.

bag type dust collector

Belonging to a filter vacuum cleaner. ? It is a dusty airflow through the filter material. Separate dust? Trap device ? The dusty gas enters the cylindrical filter bag from the lower part. When passing through the gap of filter cloth, dust particles are due to inertia. Contact and diffusion are intercepted. If the dust particles and the filter material have opposite charges, the dust particles are adsorbed on the filter material. Can you improve the dust removal efficiency? But it is difficult to clean up the ashes; ? If it has the same charge. Dust removal efficiency decreases, but dust removal is easier. Bag filter can remove dust particles with particle size above 0. 1 micron, and the dust removal efficiency is 99%. The air pressure loss is100 ~ 200mm water column. The cloth bag material can be natural fiber or synthetic fiber textiles or felt products; When purifying high temperature gas, glass fiber can be used as filter material.

According to the different cleaning methods of filter cloth, it can be divided into three types:? Intermittent cleaning type is to temporarily stop working, remove accumulated dust by knocking or vibration, or reverse purging with compressed air; Periodic cleaning type is several groups of bag filters, which stop the work of one group at regular intervals in sequence and then clean; Continuous cleaning type is to remove accumulated dust by continuously moving gas ring back blowing or pulsed air back blowing. Pulse dust collector is used to remove accumulated dust. The disadvantage of bag filter is that it has no cooling effect on the passing gas and occupies a large area; Its advantages are simple equipment and high dust removal efficiency, and the recovered dry dust can be directly used.

Acoustic wave dust collector

Sound waves vibrate dusty gases. Cause dust particles to vibrate, dust particles collide with each other, and then condense. Acoustic wave dust collector is composed of acoustic wave generation source,? Condensing tower? Vacuum cleaner, etc. It is usually used in series with centrifugal dust collector. ? The sound wave source is located in the upper part of the condensation tower. The intensity generated in the condensing tower is about? 150 decibel sound waves make dust particles collide and condense. Dust particles are trapped in a tower with an effective height of 10 ~ 20m for several seconds to more than ten seconds, and then collected by a dust collector. Sonic dust collector can treat dust particles with particle size of 0. 1 ~ 100 micron, with pressure loss of 60 ~ 100 mm water column and dust removal efficiency of 80 ~ 95%. It is characterized by strong adaptability, can handle high temperature and high concentration dusty gas, and can also be used in wet state, but it is noisy. Electrostatic precipitator1906 F.G. cottrell was successfully developed for the first time, so it is also called cottrell electrostatic precipitator. It uses a strong electric field.

The gas is ionized, and the dust in the gas is also charged and separated from the gas under the action of electric field.

There are two kinds of electrode forms of dust collector: flat plate type and tube type. The negative electrode is usually called the discharge electrode. The positive electrode is called a dust collecting electrode (or a settling electrode). ? Like the handle of a tubular electrostatic precipitator? 220V (or 380V) alternating current is converted into 30000 ~ 6000V high voltage direct current through step-up rectifier, and enters the insulated corona wire. The cylinder wall is a dust collecting electrode, an electrostatic field is formed between the corona wire and the cylinder wall, and the air around the corona wire is ionized, forming a large number of negative ions and electrons, which move to the dust collecting electrode. Dust-containing gas enters the dust collector from the inlet of the dust collector, and the uncharged dust particles combine with negative ions to be negatively charged. After moving to the dust collecting electrode, they lose charge and become neutral, and then fall into the ash hopper along the dust collecting electrode through vibration. The purified gas is discharged from the outlet of the dust collector. The energy consumption of electrostatic precipitator is lower than that of other precipitators. The pressure loss of airflow is generally 10 ~ 50 mm water column, and the dust removal efficiency is as high as 90 ~ 99.9%. It is suitable for removing dust particles with a particle size of 0.05 ~ 50 microns, and can be used in high temperature and high pressure occasions and can run continuously. Disadvantages are huge equipment and high investment.

Other types of dust collectors

In addition to the above-mentioned various dust collectors that have been finalized and produced, there is also a high gradient magnetic dust collector. Electrostatic wet dust collector? Ceramic filter dust collector, etc. ? What are the dust particles in the waste gas of iron and steel industry? More than 70% has strong magnetism, so a high gradient magnetic filter can be used. For example, converter dust, mainly strong magnetic particles, is captured by magnetic filter with particle size greater than 0.8 micron, with efficiency of 99% and pressure loss of 65,438+0.70 mm water column.

The electrostatic wet dust collector is equipped with a high voltage ion generator. Charge the dust particles in the airflow before entering the packaging washing area. Charged dust particles are attracted by fillers and washed away by water. ? Can this dust collector remove the particle size? The efficiency of 0. 1 micron dust particles can reach 90%. Ceramic filter dust collector adopts microporous ceramics as filter material, which can be used for dust removal of high temperature gas. The micropores of the filter material can be made into different pore sizes. If the pore size is 1 micron and the particle size is above 1 micron, all dust can be collected. According to the test, when the pore size is 0.85 micron, dust particles with particle size larger than 0. 1 micron can also be captured.