Question

Question 2 (8 Marks) A centrifuge that has a 60em ID and is 45 cm long has an overflow weir that is Sem wide. The centrifuge operates at a speed of 4000 rpm What is the maximum capacity of the centrifuge in gpm for which particles with a diameter of 30pm and SG 1.5 can be separated from a water suspension? Take water density as 1000kg/m and water viscosity as 0.0009 Pa-s Useful equations: - 18μ dr 2AN/60

Answer 1

Here,

r1=4 cm

r2=30 cm

d (diameter of fluid particle) = 30$\mu m$

2X3.14X4000 60

μ 0.0009Pa.s

Density of particles=S.GX1000=1.5X1000=1500 kg/m3

Density of water=1000kg/m3

The time taken by fluid particle to go from r1 to r2 is given by the equation mentioned in the question:

18,1 11 1

Substituting the values we get:

t=0.2053 sec

Now the total volume capacity is given by
V = π( r22-r12) H = 0.12477

Volumetric flow rate  

Q=-=-= O 0.124 0.60m3/s 95 10.20pm 0.60m3/s-95 10.2gprn

(1m3/s- 15850.32gpm)