Dust collector

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Dust collectors are systems used to improve the air quality that is removed from industrial and commercial processes by collecting dust and other impurities from air or gas. Designed to handle high volume dust loads, the dust collection system consists of blowers, dust filters, filter cleaning systems, and dust containers or dust removal systems. It is distinguished from air purifiers, which use disposable filters to remove dust.

Video Dust collector

History

The dust-collector's father was Wilhelm Beth of LÃÆ'¼beck. In 1921, he patented three filter designs he pioneered to remove dust from the air.

Maps Dust collector

Usage

Dust collectors are used in many processes to recover granular grain or valuable powder from the process stream, or to remove granular solids from the flue gas before being discharged into the atmosphere. Dust collection is an online process for collecting dust generated processes from a continuous source point. The dust collector may be a single unit construction, or collection of devices used to separate particulate matter from the process air. They are often used as a means of controlling air pollution to maintain or improve air quality.

Fog collectors move particles in the form of fluid droplets from the air. They are often used for metal working fluid collection, and coolant or oil. Fog collectors are often used to improve or maintain air quality in the workplace environment.

Smoke and smoke collectors are used to remove sub-micrometer-sized particles from the air. They effectively reduce or remove particles and gas flow from many industrial processes such as welding, rubber and plastic processing, high speed machining with cooling, tempering, and quenching.

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Type of dust collector

The five main types of industrial dust collectors are:

• Inertial separator
• Fabric filter
• Wet scrubber
• Unit collector
• electrostatic precipitator

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Inertia separator

The inertia separator separates the dust from the gas stream using a combination of forces, such as centrifugal, gravity, and inertia. These forces transfer dust to areas where the force provided by the gas flow is minimal. Separate dust is driven by gravity into the hopper, where it is temporarily stored.

The three main types of inertial separators are:

• Deposition room
• Baffle chambers
• Centrifugal collector

Both deposition chambers or baffle chambers are commonly used in the mineral processing industry. However, their operating principles are often incorporated into more efficient dust collector designs.

Deposition spaces

A deposition chamber consists of large boxes that are installed in need of ducts. Increased cross-sectional area in space reduces the speed of dust-filled airflow and the heavier particles precipitate. The deposition chamber is simple in design and can be made from almost any material. However, they are rarely used as major dust collectors due to large space requirements and low efficiency. Practical use is as a precleaner for more efficient collection. Advantages: 1) simple construction and low cost 2) maintenance free 3) collect particles without water. Disadvantages: 1) low efficiency 2) large space required.

Baffle chamber

Baffle chambers use a fixed baffle plate that causes a flow of gas to flow to make a sudden change of direction. Large diameter particles do not follow the gas flow but continue into the air chamber die and settle. Baffle chambers are used as precleaner

Centrifugal collector

Centrifugal collectors use cyclone action to separate dust particles from the gas stream. In an ordinary typhoon, the dust gas stream enters a corner and rotates rapidly. The centrifugal force created by the circular flow throws dust particles toward the cyclone wall. After hitting the wall, these particles fall into the hopper located underneath.

The most common types of centrifuges, or inertia, collectors used today are:

Single-cyclone separator

The single-cyclone separator creates a double vortex to separate the coarse from the fine dust. The main whirl turns down and carries most of the coarse dust particles. The inner whirl, made near the bottom of the cyclone, spirals upward and carries the finer particles of dust.

Multi-cyclone separator

The multi-cyclone separator consists of a number of small diameter cyclones, operates in parallel and has a common gas inlet and outlet, as shown in the figure, and operates on the same principle as a single cyclone separator - creating the lower vorta to the outside and an inner vortex which is uphill.

The multi-cyclone separator eliminates more dust than a single cyclone separator because each cyclone has a larger length and a smaller diameter. Longer lengths provide longer residence time while smaller diameters create greater centrifugal force. Both of these factors result in better separation of dust particulates. The decrease in multi-cyclone separator-collector pressure is higher than that of a single cyclone, which requires more energy to clean up the same amount of air. The same one-cell cyclone separator is more economical, but does not remove much dust.

Cyclone separators are found in all types of power and industrial applications, including pulp and paper mills, cement plants, steel mills, petroleum coke factories, metallurgical plants, saw mills and other dust processing facilities.

Secondary airflow separator

This type of cyclone uses secondary airflow, injected into a cyclone to achieve several things. Secondary airflow increases the speed of cyclone action making separators more efficient; it cuts the particles before reaching the inner walls of the unit; and it forces a separate particulate into the collection area. The secondary air stream protects the separator from the abrasion particles and allows the separator to be horizontally mounted because the gravity is independent to move the separated particles downward.

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Fabric filters

Generally known as baghouses, fabric collectors use filtration to separate dust particles from dusty gases. They are one of the most efficient and cost-effective dust collectors available, and can achieve a collection efficiency of over 99% for very fine particulates.

Dust-loaded gas enters the baghouse and passes through a fabric bag that acts as a filter. The bag can be of cotton or woven fabric, synthetic, or glass fiber either in the form of a tube or envelope.

Pre-coating

To make sure the filter bag has a long lifetime, it is generally coated with filter enhancer (pre-layer). The use of inert limestone chemical limestone (calcium carbonate) is most common because it maximizes the efficiency of dust collection (including fly ash) through the formation of so-called cakes or layers on the surface of filter media. It not only traps fine particulates but also provides protection for the pouch itself from moisture, and greasy or sticky particulates that can bind to filter media. Without a pre-layer bag filter allows fine particles to bleed through the bag filter system, especially during start-up, since the pouch can only perform parts of the filtration leaving a finer part to the cake filter enhancer.

Section

Fabric filters generally have the following parts:

1. Clean plenum
2. Dusty plenary
3. Bags, cages, venturi assembly
4. Tubeplate
5. RAV/SCREW
6. Compressed air header
7. The inflatable pipe
8. Housing and hopper

Types of bag cleaning

Baghouse is characterized by their cleaning methods.

Shaking

A rod connected to this pocket is supported by a motor. This provides a movement to remove coated particles. Speed ​​and movement of shocks depends on bag design and particulate composition. Generally vibrate horizontally. The top of the bag is closed and the bottom is open. When shaken, the dust collected on the inside of the bag was released. During the cleaning process, no dirty gas flows through the bag while the bag is being cleaned. This airflow diversion illustrates why baghouse should be boxed.

Reverse air

Airflow gives the bag structure. Dirty air flows through the bag from the inside, allowing dust to collect on the interior surface. During cleaning, the gas stream is limited from certain compartments. Without the air flowing, the bags relax. The cylindrical bag contains a ring that prevents it from fully collapsing under air pressure. A fan blows clean air in the opposite direction. Relaxation and reverse airflow causes the dust cake to collapse and release into the hopper. After the cleaning process is complete, the dirty airflow continues and the bag regains its shape.

Pulse jet

This type of baghouse cleanup (also known as jet-pressure cleaning) is the most common. A high pressure air blast is used to remove dust from the bag. The explosion enters the top of the bag tube, temporarily stopping the flow of dirty air. The air shock causes the expansion wave to move down the fabric. Splash the bag and destroy the dust cake. The air bursts about 0.1 seconds and it takes about 0.5 seconds for the shock wave to travel down the length of the bag. Due to its rapid discharge, the explosion of air does not interfere with the flow of contaminated gas. Therefore, baghouse pulse-jets can operate continuously and are usually not compartmentalized. The compressed air explosion must be strong enough to ensure that the shock waves will roam the entire length of the bag and break the dust cake. The efficiency of a cleaning system makes it possible to have a higher gas-to-fabric ratio (or gas volumetric throughput per unit of filter area) rather than a shaky and reversed air bag filter. Such filters require smaller areas to receive the same air volume.

Sonic

The most common type of cleaning method is sonic. Vibration is achieved with sonic vibrations. The sound generator produces a low-frequency sound that causes the bag to vibrate. Sonic cleaners are generally combined with other cleaning methods to ensure thorough cleaning.

Cartridge collector

The cartridge collector uses a hollow metal cartridge that contains folding and pleated filtering media, as opposed to a woven bag or pouch used in a storage house. The pleated design allows for a larger total filter surface area than in a conventional pocket of the same diameter. The larger the filtering area produces a reduction of air to the media ratio, pressure drop, and overall collector size.

Cartridge collectors are available in single use or continuous task design. In a single-use collector, the dirty cartridge is altered and the collected debris is removed when the collector is turned off. In a continuous duty design, the cartridges are cleaned by a conventional pulley cleaning system.

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Wet scrubber

Liquid dust collectors are known as wet scrubbers. In this system, the scrubbing fluid (usually water) is in contact with the gas stream containing dust particles. Larger contacts of gas and liquid streams result in higher dust removal efficiency.

There are a variety of wet scrubbers; However, all have one of three basic configurations:

1. Gas-humidification - The gas-humidification process agglomerates fine particles, increases bulk, makes collection easier.

2. Gas-liquid contact - This is one of the most important factors affecting the efficiency of collection. Particles and droplets come in contact with four main mechanisms:

a) Inertial impaction - When a water droplet is placed in a dust-filled gas flow path, the stream separates and flows around it. Due to inertia, larger dust particles will continue in straight paths, hit droplets, and become encapsulated.

b) Interception - The smoother particles moving in the gas stream do not hit the drip directly but brush and stick to it.

c) Diffusion - When fluid droplets are dispersed among dust particles, particles are deposited on the droplet surface by Brownian motion, or diffusion. This is the main mechanism in collecting submicrometre dust particles.

d) Condensation nucleation - If the gas passing through the scrubber is cooled below the dew point, condensation of water vapor occurs on dust particles. This increase in particle size makes collection easier. â € <â € <

3. Gas-liquid separation - Regardless of the contact mechanism used, as much as possible the liquid and dust must be removed. After contact is made, dust particles and water droplets combine to form agglomerates. As the agglomerates grow larger, they settle into collectors.

The "cleaned" gases are usually passed through a demister pads to remove the water droplets from the gas stream. The dirty water from the scrubber system is cleaned and thrown away or recycled to the scrubber. Dust is removed from scrubbers in clarification units or tank chains. In both systems, solid materials settle at the bottom of the tank. The drag chain system removes precipitate and sediment into the trash or stockpiling.

Type scrubber

Wet scrubber of wet springs can be categorized by the following pressure drops:

• Low-energy scrubber (water gauge 0.5 to 2.5 inches - 124.4 to 621.9 Pa)
• Low to medium scrubber (water gauge 2.5 to 6 inches - 0.622 to 1,493 kPa)
• Medium-to-high-energy scrubber (water gauge 6 to 15 inches - 1,493 to 3,731 kPa)
• High-energy scrubber (larger than 15-inch water gauge - greater than 3,731 kPa)

Due to the large number of commercial scrubbers available, it is not possible to describe each individual type here. However, the following sections provide a typical scrubber example in each category.

Low-energy scrubber

In a simple gravity-spray-tower scrubber, the liquid droplets formed by the atomized liquid in the nozzle spray fall through the increase of the flue gas. Dirty water is drained at the bottom.

These scrubbers operate at a pressure drop of 1 to 2 inches. Water gauges (¼ to ½ kPa) and approximately 70% efficient on 10 Âμm particles. Their efficiency is poor under 10 Âμm. However, they are able to treat relatively high concentrations of dust without having to plug it in.

Low to medium scrubbers

Wet cyclones use centrifugal force to rotate dust particles (similar to cyclones), and toss particulates onto the walls of wet collectors. Water is inserted from the top to wet, the cyclone wall carrying these particles away. Wet walls also prevent dust reentrainment.

Pressure drops for these collectors range from 2 to 8 in water. (½ to 2 kPa), and good collection efficiency for 5 m particles and above.

High-energy screwdriver joint scouring current flow

The packed bedding consists of a packing bed bed, such as a coke, broken pieces of stone, rings, saddles, or other elements produced. The packing breaks the flow of liquid into a large surface film so that the dusty gas stream passing through the bed reaches the maximum contact with the liquid film and becomes deposited on the surface of the packing element. The scrubber has a good collection efficiency for inhalable dust.

Three types of bed scrubbers are:

• Cross-flow Scrubber
• The roller of the shared stream
• Scrubber stream counter current

Efficiency can be greatly enhanced by minimizing target size, that is, using 0.003 inch (0.076 mm) diameter stainless steel wire and increasing gas speed up to more than 1,800 feet/min (9.14 m/s).

High-energy scrubber

Venturi scrubber consists of inlets and venturi-shaped separators. The gas-loaded venturi dust scrubber enters through the venturi and is accelerated to speeds between 12,000 and 36,000 feet/min (60.97-182.83 m/s). These high gas velocities immediately sprayed a rough spray of water, which was injected radially into the venturi's throat, into fine droplets. High energy and extreme turbulence push the collision between water droplets and dust particles in the throat. The agglomeration process between the particles and the droplet continues in the venturi divergent part. The large clumps formed in the venturi are then removed by inertia separators.

Venturi scrubbers achieve a very high collection efficiency for inhaled dust. Because the efficiency of venturi scrubbers is dependent on pressure drop, some manufacturers supply variable-throat venturi to maintain pressure drop with various gas streams.

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Electrostatic precipitators use electrostatic forces to separate dust particles from exhaust gases. A number of high voltage discharge electrodes, the direct current is placed between the grounded collector electrodes. The contaminated gas flows through the channels formed by the exhaust and collects the electrodes. Electrostatic precipitators operate on the same principle as "Ionic" home air purifiers.

The air particle receives a negative charge as they pass through the ionized field between the electrodes. The charged particles are then attracted to a grounded or positively charged electrode and adhere to it.

Materials collected on electrodes are eliminated by knocking or vibrating collector electrodes either continuously or at specified intervals. Cleaning the precipitator can usually be done without disturbing the airflow.

The four main components of all electrostatic precipitators are:

• Power supply unit, to provide high-voltage DC power
• The ionizing part, to give the charge to the particulate in the gas stream
• Tool for removing collected particles
• Housing to attach a precipitator zone

The following factors affect the efficiency of electrostatic precipitators:

• Larger collecting surface areas and lower gas flow rates increase efficiency due to increased time available for electrical activity to treat dust particles.
• Increasing the speed of migration of dust particles to the collecting electrodes improves efficiency. Migration speed can be improved by:
  • Reduce the gas viscosity
  • Increase the gas temperature
  • Increases the stress field

Type precipitators

There are two main types of precipitators:

• High voltage, single stage - Single stage precipitator combines ionization and collection steps. They are usually referred to as Cottrell precipitators.
• Low-voltage, two-stage - Two-stage precipitators use the same principle; however, the ionizing section is followed by the collection plate.

Described below is a high voltage precipitator, one stage, which is widely used in mineral processing operations. Two-stage low-voltage deposits are generally used for filtering in air-conditioning systems.

Plate precipitators

The majority of electrostatic precipitators installed are plate types. The particles are collected on a flat, parallel surface that is 8 to 12 inches (20 to 30 cm) apart, with a series of discharge electrodes placed along the center line of two adjacent plates. The contaminated gas passes through the aisle between the plates, and the particles become filled and attached to the collecting plate. Collected particles are usually removed by tapping the plates and stored in a bin or hopper at the base of the precipitator.

Presular tubular

Tubular precipitators consist of a cylindrical collection electrode with a discharge electrode located on the cylinder axis. The contaminated gas flows around the exhaust electrode and rises through the inside of the cylinder. The charged particles are collected on the ground wall of the cylinder. Collected dust is removed from the bottom of the cylinder.

Tubular precipitators are often used for fog or mist collection or for sticky, sticky, radioactive, or highly toxic materials.

Unit collector

Unlike central collectors, unit collectors control contamination at the source. They are small and self-contained, consisting of a fan and some form of dust collector. They are suitable for isolated, portable, or often removable dust generation operations, such as trash cans and silos or belt-conveyor remote transfer points. The advantages of unit collectors include small space requirements, the return of dust accumulated to the main material stream, and low initial cost. However, their storage and dust storage capacity, service facilities, and maintenance periods have been sacrificed.

A number of designs are available, with capacities ranging from 200 to 2,000Ã, ftÃ,³/min (90 to 900Ã, L/s). There are two main types of collector units:

• Fabric collectors, with manual milling or pulse-jet cleaning - are usually used for fine dust
• Cyclone Collector - commonly used for rough dust

Fabric collectors are often used in mineral processing operations because they provide high collection efficiency and uninterrupted exhaust airflow between cleaning cycles. Cyclone collectors are used when coarse dust is produced, such as in woodworking, metal grinding, or machining.

The following points should be considered when choosing a unit collector:

• Cleaning efficiency must comply with all applicable regulations.
• The unit retains its rated capacity while collecting large amounts of dust between cleanups.
• Simple cleaning operation does not increase the concentration of dust around it.
• Have the ability to operate unattended for a long time (for example, 8 hours).
• Automatic dump or dust storage space sufficient to withstand at least one week of accumulation.
• If renewable filters are used, they should not be changed more than once a month.
• Durable
• Calm

The use of unit collectors may not be appropriate if dust-producing operations are located in areas where central exhaust systems will be practical. Dust removal and service requirements are expensive for many unit collectors and are more likely to be ignored than single large collectors.

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Choose a dust collector

Dust collectors vary greatly in terms of design, operation, effectiveness, space requirements, construction, and capital, operations, and maintenance costs. Each type has advantages and disadvantages. However, the selection of dust collectors should be based on the following general factors:

• Concentration of dust and particle size - For mineral processing operations, dust concentrations can range from 0.1 to 5.0 grains (0.32 g) of dust per cubic foot of air (0.23 to 11.44 grams per standard cubic meters), and the particle size may vary from 0.5 to 100 micrometers (Ã,Âμm) in diameter.
• The required dust collection rate - The required level of dust collection depends on its potential as a health hazard or public disturbance, factory location, allowable emission level, dust properties, residual value, and so on. Collector selection should be based on the required efficiency and should consider the need for efficient and high-cost equipment, such as electrostatic precipitators; high efficiency equipment at moderate cost, such as storage or wet scrubbers; or lower cost, main unit, such as dry centrifugal collector.
• Airflow characteristics - Airflow characteristics can have a significant impact on collector selection. For example, a cotton cloth filter can not be used where the air temperature exceeds 180 ° F (82 ° C). Also, condensation vapor or moisture can blind the bag. Various chemicals can attack cloth or metal and cause corrosion on wet scrubbers.
• Characteristics of dust - Medium to heavy concentrations of a lot of dust (such as dust from silica sand or metal ores) may be abrasive for dry centrifugal collectors. Hygroscopic materials can wrap bag collectors. The sticky material can be attached to the collector elements and plug channels. Some particle sizes and shapes may override certain types of cloth collectors. The combustible properties of many fine materials override the use of electrostatic precipitators.
• Disposal methods - Methods of dust removal and disposal vary with the material, factory process, volume, and type of collector used. Collectors can unload continuously or in batches. Dry matter may cause secondary dust problems during discharge and disposal that do not occur in wet collectors. Disposal of wet mud or mud may be a matter of handling additional materials; ditch or water pollution problems can occur if wastewater is not handled properly.

Fan and motor

Fan and motor systems supply mechanical energy to transfer contaminated air from dust-producing sources to dust collectors.

Fan type

There are two main types of industry fans:

• Centrifugal fans
• Axial stream fan

Centrifugal fans

The centrifugal fan consists of a wheel or rotor mounted on a rotating shaft in a roll-shaped housing. The air enters the rotor's eye, makes a right-angle turn, and is forced through the rotor blades by centrifugal force into the shaped housing of the roll. The centrifugal force gives static pressure to the air. Different scrolls also change some of the pressure velocity into static pressure.

There are three main types of centrifugal fans:

• Radial-blade fans - Radial-blade fans are used for heavy dust loads. Their straight radial blades are not clogged by the material, and they withstand considerable abrasion. This fan has medium tip speed and medium noise factor.
• Backward-blade fans - Backward blade enthusiasts operate at higher tip speeds and are thus more efficient. Since the material can accumulate on the propeller, this fan should be used after the dust collector. Although they are more noisy than radial-blade fans, rear blade fans are usually used for large volume dust collection systems because of their higher efficiency.
• Curved blades forward - This fan has a curved blade that leads in the direction of rotation. They have low space requirements, low tip speed, and low noise factor. They are usually used against low to medium static pressure.

Axial flow fan

Axial flow fan is used in systems that have low resistance levels. This fan moves the air parallel to the fan rotation axis. The screw-like action of the propellers moves air in a straight parallel path, causing a helical flow pattern.

The three main types of axial fans are:

• Propeller fans - These fans are used to move large amounts of air against very low static pressure. They are usually used for general ventilation or dilution ventilation and are good at developing up to 0.5 inches. (124.4 Pa).
• The axial fan of the tube - The axial fan of a tube is similar to a propeller fan unless mounted on a tube or cylinder. Therefore, they are more efficient than propeller fans and can develop up to 3 to 4 inches across. Wg (743.3 to 995 Pa). They are best suited for moving air containing substances such as smoke or conditioned pigments.
• Propeller Fan - A propeller fan is similar to an axial-axial fan except an air straightener blade mounted on the suction side or rotor discharge. They are easily adapted to multistaging and can develop static pressure as high as 14 to 16 inches across. Wg (3.483 to 3.98 kPa). Usually used only for clean air.

Fan selection

When selecting a fan, the following points should be considered:

• Volume required
• Fan static pressure
• The type of material to be handled via fan (For example, radial-blade fans should be used with fibrous materials or heavy dust loads, and nonsparking construction should be used with explosives or flammable.)
• Drive setting type, such as direct drive or drive belt
• Space requirements
• Noise level
• Operating temperature (For example, the arm bearings are suitable for 250 ° F/121.1 ° C, ball bearings up to 550 ° F/287.8 ° C).
• Adequate size to handle required volume and pressure with minimum horsepower
• The need for special coatings or construction when operating in a corrosive atmosphere
• Fan capability to accommodate small changes in total pressure while maintaining required air volumes
• The need for an outlet damper to control airflow during a cold start (If necessary, dampers may interlock with fans for a gradual beginning until steady-state conditions are reached.)

Fan Ranking Table

Once the above information is collected, the actual fan size and fan selection is usually made from the ratings table published by the fan manufacturer. This table is known as a multirating table, and it shows a complete range of capacity for certain fan sizes.

Points to note:

• The multirating table shows possible pressure and speed ranges within the limits of fan construction.
• Certain fans may be available in different construction classes (identified as classes I to IV) relating to capabilities and limits.
• For certain pressures, the highest mechanical efficiency is usually found in the middle third of the volume column.
• Fans who operate at a certain speed can have unlimited ratings (pressure and volume) along the characteristic curve. However, when the fan is installed in the dust collection system, the rating point can only be at the point where the system resistance curve intersects the fan characteristic curve.
• In some systems, fans at fixed speed or in fixed blade settings can only have a single rating. This rating can be changed simply by changing the fan speed, blade settings, or system endurance.
• For certain systems, increasing the exhaust volume will result in an increase in static and total pressure. For example, for a 20% increase in exhaust volume in systems with a pressure of 5 in., The new pressure will be 5 ÃÆ'â € "(1.20) ² = 7.2 in.
• o For a quick estimate of the possible disposal volume available for the given motor size, the equations for brake horsepower, as illustrated, can be useful.

Fan installation Typical fan release conditions Fan ratings for volume and static pressure, as described in multirating tables, are based on tests conducted under ideal conditions. Often, field installations create airflow problems that reduce air fan delivery. The following points should be considered when installing the fan:

• Avoid elbow or bend installation on fan discharge, which will decrease fan performance by increasing system endurance.
• Avoid installing fittings that can cause uniform flow, such as elbows, mitred elbows, or square channels.
• Check whether the impeller fan is rotating in the right direction, clockwise or counterclockwise.
• For belt-driven fans:
  • Check that the sheave motor and sheave fan are aligned correctly.
  • Check if there is a proper belt tension.
• Check the parts between the entrance holes, the impeller blades, and the inside of the housing for the buildup of dirt, obstructions, or trapped foreign objects.
Electric motors

The electric motor is used to supply the energy needed to drive the fan.

Integral-horsepower electric motors are usually three-phase, alternating-current motors. Horsepower-fractional electric motors are usually single-phase, alternating-current motors and used when less than 1 hp (0.75 kW) is required. Since most dust collection systems require motors with more than 1 hp (0.75 kW), only the horse-integral motor is discussed here.

Two types of integral motors-the most common horsepower used in dust collection systems are:

• Squirrel-cage motor - This motor has a constant speed and non-synchronized induction type.
• Motor scattering-rotor - This motor is also known as a slip-ring motor. They are general purpose motors or constantly rated and are mainly used when the desired speed-adjustable motor is desired.

Squirrel-cage motors and rotor are further classified according to the type of enclosure used to protect the interior rolls. This appendix is ​​divided into two broad categories:

• Open
• Completely closed

The drip-resistant and anti-sparking motor is open motor. They provide different levels of protection; However, they should not be used where the air contains substances that may be harmful to the motor interior.

Fully enclosed motorcycles are weather-protected with covered rolls. This enclosure prevents the exchange of free air between the inside and outside, but not airtight.

The motor is completely closed, the cooling fan (TEFC) is another type of motor that is completely enclosed. These motors are the most common motors used in dust collection systems. They have an integral cooling fan outside the enclosure, but inside a protective shield, which directs air above the enclosure.

Both open and completely closed motors are available in blast-resistant and contact-resistant models to protect against explosions and fires in hazardous environments.

The motor is selected to provide sufficient power to operate the fan through various process conditions (temperature and flow rate).

Configuration

Dust collectors can be configured into one of five common types:

1. Ambient units - An ambient unit is a free hanging system to use when an application limits the use of a source-catching arm or requires a work line.
2. Collection chambers - Collector chambers require no air ducts, and allow greater freedom of movement for workers. They are often portable.
3. Downdraft table - Downdraft table is a self-contained portable filtration system that removes harmful particles and returns filtered air back to the facility without the need for external ventilation.
4. Source collector or Portable unit - Portable unit for collecting dust, fog, smoke, or smoke at the source.
5. Stationary unit - An example of stationary collector is baghouse.

Parameters involved in determining dust collector

Important parameters in determining dust collectors include airflow velocity velocities made by vacuum manufacturers; power system, motor power system, usually specified in horsepower; storage capacity for dust and particles, and minimum particle size filtered by the unit. Other considerations when choosing a dust collection system include temperature, moisture content, and the possibility of burning dust collected.

Systems for fine deletion can only contain a single filtering system (such as filter bags or cartridges). However, most units use a primary/secondary separation/separation system. In many cases, the heat or moisture content of the dust can negatively affect the filter media from the baghouse or cartridge dust collector. The cyclone separator or dryer may be placed before the unit to reduce heat or moisture before it reaches the filter. In addition, some units may have third and fourth stage filtration. All separation and filtration systems used in the unit shall be determined.

A baghouse is an air pollution reduction tool used to trap particulates by filtering the flow of gas through a large cloth bag. They are usually made of glass fibers or fabrics.

Cyclone separator is a tool for separation, by centrifugal, fine particles suspended in air or gas.

Electrostatic precipitators are a type of air purifier, which fills dust particles by passing dust-filled air through a strong electrostatic field (50-100 kV). This causes the particles to be attracted to the opposite charge plate so that it can be removed from the airflow.

The impinger system is a device in which particles are removed by affecting the aerosol particles into liquids. Modular media type units incorporate a variety of custom filter modules in a single unit. This system can provide solutions to many air contaminant problems. Typical systems incorporate a series of pre-disposable or clean filters, vee-bag filters or disposable cartridges. The final HEPA or carbon filter module can also be added. A variety of models are available, including hanging or channeled installations, vertical or horizontal mounting, and fixed or portable configurations. Filter cartridges are made of various synthetic fibers and are able to collect sub-micrometer particles without creating excessive pressure drop in the system. The filter cartridge requires periodic cleaning.

Wet scrubber, or venturi scrubber, is similar to a cyclone but has an orifice unit that sprays water into a vortex in the cyclone, collecting all the dust in the slurry system. Water media can be recirculated and reused to continue filtering the air. Finally, solids must be removed from the stream and disposed of.

Filter cleanup method

Online cleaning - automatic filter cleaning that allows continuous and continuous dust collector operation for heavy dust operations.

Offline cleanup - filter cleaning done during the dust collector is closed. Practically whenever the dust load in each dust collector cycle does not exceed the capacity of the filter. Allows for maximum effectiveness in removing and disposing of dust.

Cleanser on request - filter cleaning begins automatically when the filter is fully loaded, as determined by the pressure drop set across the media surface.

Reverse-pulse/Reverse-jet Cleaning - A filter cleaning method that provides a compressed air blast from the clean side of the filter to dissipate the collected dust.

Impact/Rapper Cleaning - A filter cleaning method in which high speed compressed air forced through a resilient tube produces arbitrary rapping of the filter to remove the dust cake. Very effective when the dust is very smooth or sticky.

See also

• Axial fan design

References

External links

• Cyclone Dust Collector Research Do yourself a Collections Dust for a home to a small-scale shop written by engineers damaged by lung.
• EPA Air Pollutants and Control Technique Additional information on various topology and wet scrubber techniques
• Deswirl Device for Cyclone Dust Dissipation PDF Scientific study of deswirl devices written by M.Z. Abdulla, Z. Husain & amp; S.M. Engineering Engineering School Fraser Penang Malaysia 2003, the device turns part of the vortex energy back into pressure energy, reducing the pressure drop.
• Rod Cole's article, "The Foundation of PVC and Other Dust Collection Myths Deep research reveals many of the myths surrounding the use of non-metallic pipes in dust collecting dust.
• Collectors' Dust Collector Guides Additional information related to the correct procedure for maintaining dust collectors
• How Dust Collecting Systems Work in Mine and Quarry Additional information breaks down every process of the Mine and Mining Collection System

This article incorporates public domain material from a United States Government document "https://www.osha.gov/SLTC/silicacrystalline/dust/chapter_4.html".

Source of the article : Wikipedia