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Cyclones 105

For d > B,
c
 ( H − h)    d  
Z = ( H − S) −    c − 1  (26)
c
c ( 
 DB) − 1    B  
For d < B,
c
Z = ( H − S) (27)
c
The maximum tangential gas velocity, v , is given by
tmax
 ab  0.61  D  − 0.74  H  − 0.33
v tmax = 6.1 v i   e    (28)
 D   D   D 
2
c
c
c
where v is the gas velocity at the cyclone entry:
i
v = Q (29)
i
ab
The exponent β in Eq. (23) is dependent on the cut diameter, and a correlation was
derived from 11 experiments at ambient temperature (13,24,25):
 ab    ab   2
lnβ = 0.62 − 0.87 ln(D 50) + 5.21 ln   + 1.05  ln    (30)
 D c 2     D c 2   

with D in centimeters.
50
2.3. Correlations for Cyclone Pressure Drop
The pressure drop, ∆P, in a particle-free cyclone can be estimated by

∆P = ρv i 2 ∆H (31)
2
where ∆H is a dimensionless parameter that depends on the cyclone geometry (1,23) and
can be calculated by the following correlation proposed by Shepherd and Lapple (26):
 ab 
∆H = 16   (32)
 D 
2
e
Alternatively, Casal and Benet (27), after performing a number of experimental tests,
adjusted (with a standard deviation of 1.61 against the 2.58 of Shepherd and Lapple) the
following expression:
 ab  2
∆H = 11 .3   + . 3 33 (33)
 D 
2
c
Ramachandran et al. (24), based on 98 cyclone configurations, statistically deter-
mined the best correlation for predicting ∆H that had the following form:
1
 ab   SD  3
∆H = 20    c  (34)
 D  (  HD )( h D )( B D )
2
c 
e 
c
c