3. Tower diameter An upward air superficial velocity of 1.2 m * D=√
is taken.
= 14.5 m
Take a tower diameter of 14.5 m leading to an air superficial velocity of 1.156 m *
4. Terminal velocity = 1.5 * Assume
=
= 6.3 m *
= 567
= 0.58 (see Fig. 5.7)
Fig
Terminal velocity of particle (
)g= ) (1335 – 1.14) 9.81 = 2.311 *
(1.5 *
)
0.58 * (1.5 * So, LHS = RHS
5. Heat transfer coefficient
13.75
Heat transefer coefficient 6. Solidification time Ph =
(
(
(
)
)
(
) )
Bi = Fo = Ph ( a=
)
(
)
(
)
(
)
Fig Correction factor for the solidification time. (From VDI, 1993.)
Corrected solidification time 7. Tower height for solidification
8. Prill cooling time
(
)
= 4 sec
(
)
(
)
(
= 1120.448
)
Cooling time
9. Prill cooling height = 3.7350 * 5.144 = 19.212 m 10. Total tower height = Height required for solidification + Height required for cooling of solidified product = 20.1727 + 19.212 = 39.38554 m, take 40 m
