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CYCLONE |
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| How
DAV’s Cyclone Works In
DAV cyclone, dusty air enters its tangential inlet,
whirls through several revolutions in the body and cone,
depositing its dust load, and departs, still whirling,
through the axial cylindrical air-outlet, under the
influence of centrifugal force, the dust particles which
have been dispersed throughout the entering stream tend
to concentrate in the thin layer of air next to the
cyclone wall, the downward helical motion of the main
air-stream and the discharge of a small quantity of
air through the dust outlet tend to project the separated
solids into the dust bin.
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Separation
Efficiency Of Cyclone
The
centrifugal force of separation is proportional to
the square of the velocity and inversely proportional
to the radius of rotation. Resistance to separation
is a function of the radial distance the dust particle
must travel to reach the cyclone wall, its gravitational
settling rate in still air, and the length of time
it is acted upon by centrifugal separating forces.
The time of exposure to these forces is a matter of
rotational speed and the number of convolutions of
the dust path from the inlet to dust outlet. |
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centrifugal force acting on a particle is:
F = wv2 / gr
where:
w = weight of particle, lb,
v = tangential velocity, ft per sec,
g = gravitational acceleration, ft per sec2,
r = radius of rotation, ft.
since the weight, w,
is the force of gravity acting on the particle, the
separating effect of a centrifugal cleaner as compared
to gravity separation is:
S = v2 / gr
where S is termed the
"separation coefficient.” the separation
coefficient of a gravity chamber is, of course, 1.0.
DAV’s cyclone has separation coefficient up to
1200. At this efficiency, particle size of 100µm
can be separated up to 99%.
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Multi Cyclones
2
identical cyclones connected in series offer little
advantage over a single cyclone. This is confirmed
by a test wherein a single cyclone captured 94% of
a certain dust and two in series raised the collecting
efficiency to only 96%.
However,
when cyclones are connected in parallel, the separation
improvement achieved relative to single bigger cyclone
is tremendous. DAV’s multi cyclones is used
in application as fine as powder coating dust, yet
meeting 0.4mg/Nm3 specification by Malaysia Department
of Environment. |
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Multi
cyclones come in the form of 2, 4, 8 and as high as
200 cyclones in one system. This tailor-made multi
cyclones are used widely in palm oil mill boilers
and smelting furnace off gas system, when conventional
filter bags can
not withstand either the elevated temperature or high
moisture content. Selection of this system requires
good command of aerodynamic and thermodynamic engineering
as well as field experience. You can rely on DAV for
this expertise. |
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pictures
shows SS316 multicyclone element that can achieve separation
of 10micron particles up to efficiency of 99.5% |
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Copyright
© 2005 DAV ENGINEERING SDN BHD |
