Sludge Treatment and Disposal 227similar machine would perform equally well. The machine variables are:
Machine 1 Machine 2Bowl diameter (cm) 20 40Bowl speed (rpm)^4000 3200
Bowl length (cm)^30 72
Conveyor speed (rpm)^3950 3150
Pitch (cm)^4 8
Number of leads^1 1Pool depth (cm) 2 4Looking first at the settling (sigma) scale-up, the volume of the sludge in the pool may
be approximated as
v = 2n ( y) (r2 - q)L, (10.11)
where the variables are defined in Fig. 10-15. The volumes of the two machines are
VI = 2n ( y) (10 - 8)(30) = 3400cm3
v2 = 2n (?) 16 + 20 (20 - 16)(72) = 32,600cm'.
Sincew1 = (4000) - (2n) = 42Orad/s
(:o)w2 = (3200) - (2~) = 335rad/s
(Qo)x1= 980 (420)2 (&) = 2.76 x lo6
= 16.8 x lo6.
(335)2 32,600
" = 980 (ln(20/16))