Page 132 - Air Pollution Control Engineering

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Cyclones 111

Fig. 4. Collection efficiency as a function of particle diameter, for three entry velocities:
curves obtained from the Barth model (12) and experimental points from Dirgo and Leith (17).

V = 0.0299 m 3
nl
Once V is known, the geometry parameter is calculated from Eq. (9):
nl
[ {
2
2
G = 0.302 m 2 2 π (0.151 m − 0.151 m 2 ) ( ( 0.302 m ) −(0.151 m ) )]
2
(0.151 m ) (0.060 m )
+ ( 4 0.0299 m 3 )}
G = 559.4
The vortex exponent [Eq. (14)] is obtained from D and the operation temperature as
c
[ 0.14 (  27 + 273 ) 0.3
n = 1 − 1 − 0.67 (0.302 )] 
 283 

n = 0.56
The relaxation time [Eq. (15)] can now be calculated as a function of particle diameter:

860 kg m 3 D i ( ) 2
τ =
i −5 )
.× 10
18 (1 8 kg ms
τ = 2654321 D 2 , with D in meters.
i i i
Therefore, the grade collection efficiency [Eq. (8)] results in