| Canadian Air Systems Co. is a engineering
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| | concurrently, counter=concurrently or in
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| company for industrial dust collecting
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| | cross-flow and are used primarily for
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| systems. Dust collecting equipment is
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| | applications involving gas, vapor and
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| available in numerous designs utilizing a
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| | mist removal.
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| number of principles and featuring wide
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| | - Wet Centrifugal Collectors
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| variation in effectiveness, initial cost,
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| | Â Wet centrifugal dust collectros
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| operating and maintenance expense, space,
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| | utilize centrifugal force to acceslerate
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| arrangements and material of
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| | the dust particle and impigne it upon a
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| construction.
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| | wetted collector surface. These
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| Factors influencing dust collection
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| | collectors are more efficient than the
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| equipment selection include:
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| | chamber type. Some are availbale with
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| * Concentration and particle size of
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| | different number of impingement sections.
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| contaminant;
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| | - Wet Dynamic Precipitators
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| * Degree of collection required;
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| | Â This type uses water sprays within a
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| * Characteristics of air or gas stream;
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| | fan housing and obtains precipitation of
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| * Characteristics of contaminant;
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| | the dust particles on the wetted surface
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| * Methods of disposal.
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| | of an impeller with special fan blade
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| Depenging on above factors, the following
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| | shape. No internal pressure drop is
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| Canadian Air Systems dust collector types
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| | involved although mechanical efficiency
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| can be utilized:
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| | is somewhat lower than the mechanical
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| ELECTROSTATIC PRECIPIRATORS
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| | efficiency of standard exhaust fans.
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| Â The principle of collection relies on
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| | - Orifice Type Collectors
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| the ability to impart a negative charge
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| | Â In this group of wet collectors
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| to particles in the gas stream causing
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| | designs, the air flow through the
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| them to move and adhere to the grounded
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| | collector is brought in contact with a
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| or positively charged collector plates.
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| | sheet of water in a restricted passage.
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| Most precipitators are made for
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| | Water flow may be induced by the velocity
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| horizontal air flow with velocities 100
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| | of the air stream or maintained by pumps
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| to 600 fpm.
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| | and weirs.
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| - Fabric Collectors
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| | - Venturi Scrubbers
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| Â Fabric arresters are high efficiency,
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| | Â This collector uses a venturi-shaped
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| medium cost collectros. Dust collection
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| | construction to establish throat
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| is obtained by building up a mat of the
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| | velocities considerably higher than those
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| material on the dirty side of the media.
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| | experienced with the orifice type. The
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| This mat provides the actual filtering or
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| | collection mechanism of the venturi is
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| straining bed. By means of this bed a
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| | impaction. As with wet collectors in
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| high degree of removal is obtained even
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| | general, the collection efficiency of the
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| on submicron size particles.
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| | venturi increases with higher pressure
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| - Intermittent-Duty Fabric Collectors
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| | drops. Different pressure drops are
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| Â These types may use either envelope
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| | achieved by designing for selected gas
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| or stocking arrangement of the fabric but
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| | velocities in the throat. The venturi
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| will generally employ shaking or
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| | iteself is a gas conditioner causing
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| vibrating as a means of reconditioning.
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| | intimate contact between particles in the
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| Periodically Uusually at 4 to 6 hour
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| | gas and the multiple jet streams of
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| intervals0 the air flow must be stopped
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| | scrubbing water.
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| to effect reconditioning - thus the
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| | DRY COLLECTORS
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| classification "intermittent".
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| | - Cyclone Dust Collectros
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| - Multiple-Section, Continuous-Duty,
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| | Â Cyclone Collectors are frequently
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| Automatic Fabric Collectors
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| | applied for the removal of coarse dusts
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| Â The disadvanteges of stopping the air
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| | from an air stream, as a pre-cleaner to
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| flow to permit vibration and variations
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| | more efficient dry or wet dust collectors
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| in the airflow can be overcomed by using
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| | and / or as a separator in product
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| of sectional arresters allowing
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| | conveying systems using an air stream to
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| continuous operation of the exhaust
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| | transport material. Principle advantages
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| system as automatic dampers periodically
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| | are low cost, low maintenance and low
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| take one section out of service for
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| | pressure drop (in order 0.75" to 1.5"
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| reconditioning the fabric while the
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| | WG), but this type dust collector can not
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| remaining sections take the entire gas
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| | be used for collection of fine particles.
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| volume.
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| | Â
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| - Reverse-Jet Fabric Collectors
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| | - High Efficiency Centrifugal Collectors
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| Â The reverse-jet type differs from the
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| | Â Have been developed whereby higher
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| conventional arrsters in its use of high
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| | centrifugal forces are exerted on dust
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| pressure air to clean the fabric. One
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| | particles in a gas stream. Improvement in
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| type uses high pressure air (30" - 40"
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| | dust separation efficiency has been
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| WG) froma travelling "blow ring" to
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| | obtained by 1) increasing velocities
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| dislodge the collected cake from inside
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| | through a cyclone shape dust collector,
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| the fabric tube. Another type uses high
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| | 2) utilizing a skimmer or other design
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| pressure compressed air (100 PSI) to
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| | feature, 3) using a number of small
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| break the dust cake from the exterior of
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| | diameter cyclones in parallel and 4)
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| the fabric tube or envelope by the
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| | placing units in series in some unusual
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| intermittent application of reverse-jet
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| | applications.
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| compressed air.
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| | - Dry Type Dynamic Precipitators
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| - Reverse-Flow Collapse, Continuous-Duty
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| | Â In this collector, dust is
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| Collectors
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| | precipitated by centrifugal force on to
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| Â Reverse-flow collapse cleaning is
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| | specially shaped blades on an exhauster
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| generally used with glass media which is
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| | wheel and then conveyed through a dust
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| fragile and requires a gentle cleaning
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| | circuit in the fan casing to the dust
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| technique. Reversing the glass flow
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| | storage hopper.
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| provides a gentle collapse of the fabric
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| | - Louver Type Dust Collectors
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| usually in a "four point star" braking
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| | Â Centrifugal forces can be applied to
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| the dust cake which falls by gravity into
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| | a particle by a rapid change in direction
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| the hopper.
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| | of air flow by series of plates set at an
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| WET COLLECTORS
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| | angle to the air stream. Coarse particles
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| Â Wet collectors are available in many
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| | traverse the air stream and will project
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| different designs. They have the ability
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| | back to the dirty air side by the forces
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| to handle high temperature and
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| | that can be produced from such an impact.
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| moisture-laden gases. The collection of
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| | - Settling Chambers
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| dust in wetted form eliminates a
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| | Â Dust is ettled out in a large chamber
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| secondary dust problem in disposal of
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| | when conveying velocities are reduced to
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| collected material. Also, some dust
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| | the point where the particles are no
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| represent explosion or fire hazard when
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| | longer conveyed. Extreme space
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| dry and wet collectors eliminate or at
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| | requirements and the presence of edde
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| least reduce the hazzard.
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| | currents to nullify the effective
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| - Chamber or Spray Tower
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| | velocity mean that settling chamber type
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| Â Consists of a round or rectangular
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| | of dust collectors can be used only for
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| chamber into which water is introduced
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| | removal of extremely coarse particles.
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| via spray nozzles. There are many
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| | - Potable Unit Collectors
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| variations in design but the principal
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| | Â To fill the need for dust collection
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| mechanism is impaction of dust particles
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| | from isolated, portable or frequently
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| on the liquid droplets created by
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| | relocated dust producing operations, a
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| nozzles. These droplets are separated
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| | number of unit collector designs are
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| from the air stream by centrifugal force
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| | availbale having capacities in the range
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| or impingement on water eliminators.
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| | of 200 to 1,000 CFM. Featuring small
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| - Packed Towers
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| | space and designed to recirculate the
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| Â Collectors in this group are
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| | air, collectors of this type have been
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| essentially contact beds through which
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| | used extensively, especially in the metal
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| gases and liquid pass either
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| | working industry.
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