dry centrifugal col lector.ppt by hitarth mihs-istar
DESCRIPTION
This is a seminar on dust collector systems, for dry dust collectors, thisis on dry centrifugal collectorsTRANSCRIPT
Dry Centrifugal Collector
By: – Hitarth MehtaMIHS - 08IH06
ISTAR
Outline
Types of ind. Collectors Dry centrifugal collectors Types of diff. DCC 1) single collectors 2) Multiclones Designing of collectors Advantages & limitations
Types of Dust Collectors
Dry mechanical collectors
Wet collectors & scrubbers
Fabric collectors
ESP
Dust collectors
Dry Centrifugal Collection
› relies on inertia› move gas in a curved path (vanes)
› large particulates collected on a separator wall
Centrifugal collectors [contd.]
Cyclonic action for dust separation
Dust stream enters & spun rapidly
Cf created by circular-flow
throws particle towards the wall of cyclone
Finally collected underneath
“Cyclonic separation”
A. Dry centrifugal collector[According to design]
1) Single cyclone collector
2) Multiple cyclone collector
Single cyclone collector
“Dual Vortex” Main vortex spirals
downwards Carries most of
coarser dust Inner vortex –near
the bottom of the cyclone
Carries finer dust & air spirals upword
Multiple-cyclone separators
“Multiclones” Consists no. of
small dia. Cyclones operating parallely
Common gas inlet & outlet
Operates on same principle as on single
Multiple-cyclone separators[contd.]
Multiclones are more efficient Longer & smaller in dia.Longer length provides longer residence time while smaller dia creates greater centrifugal forceWhich results in better separation of particulatesPressure drop is higher then that of single cyclone separators
B . Dry centrifugal collector[According to mechanism]
Gravity separators
Inertial separators
Dynamic precipitators
Cyclone collectors
High efficiency centrifugal collectors
Gravity separators
gravitational and centrifugal forces
Cyclonic separation When fluid or gas enters
the cyclone with high enough pressure, a spiral flow is created
Rough particles, being heavier, are thrown into the wall of the separator where they sink down into the bottom of the separator where they are removed
Inertial separator
inertia and gravity to separate dust particles
by slowing the flow of dusty air stream
When speed of the dusty air stream is slowed down, heavier dirt particles settle out from the air stream by gravity and fall into a hopper where they are collected.
Inertial separator
i) settling collectors
separate dust from the stream by using a settling chamber (a large box) in ductwork carrying
dusty air
A baffle plat in the path of the dusty air stream to slow it down. The air stream strikes the baffle plate and undergoes a
sudden change in direction
Dynamic precipitators
Also operates on principle of centrifugal force
Combination of specially designed centrifugal fan & dust collector
Cf generated by rotating blades pushes the particles in the air stream to the tips of the blades
From where they drawn off Unsuitable for sticky & fibrous material Fairly efficient:- 5-20 microns in dia.
High efficiency centrifugal collectors
High-efficiency separators use a high velocity vortex centrifugal action for higher separation efficiency or for pneumatic conveying.
This type requires continuous discharge from the separator by the addition of a surge hopper for material storage.
Designing
Commercially available in wide verity of designsAll depends on centrifugal force to separate dust from air stream “The magnitude of Cf which can be exerted on a particle is a funcn of particle mass and angular acceleration”Letter is dependent on air velocities in collectors
Factors influencing Design
1) Concn & particle size of contaminant2) Degree of collection required3) Characteristics of gas / air stream4) Characteristics of contaminant5) Methods of disposal
Applications
Many industrial processes likei. Millingii. Grindingiii. Abrasive blastingiv. Welding , etc. uses dust collectors to improve quality of
air inside the pant
Applications [contd.]
In industrial facilities, centrifugal collectors are used with LEV
Mainly it is used in chemical ind.
Moderate-sized dust such as wood dust,shavings,chips
10-40 microns
Advantages
Least costly & most frequently usedUsed as Primary or precollectorsLow maintenance cost Low operating costRelatively small in sizeLittle pressure dropMay use in series to increase efficiency
Limitation
“Because of today’s more stringent emission standard , the use of dry centrifugal collator is limited almost exclusively to produce recovery applications”Not effective for finer/Respirable
i.e dust particles < 5 micronCyclones used in series may have a large pressure dropsMostly used only as secondary standard
Summery
DCCs are mainly used for pre-cleaning Most commonly used for all type of
medium from coarse to fine Except < 5micron dia. Particles Low cost & maintenance All kind of sizes Collection efficiency of 10 to
100microns with Multiclones.
References
Handbook of heating , ventilating & air-conditioning
Time-saver standards for Architectural design
Basics of industrial hygiene by Debra Nims
Internet:- Wikipedia , thermax.com Directindustry.com www.dustcollectorexperts.com/ cyclone/
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