Velocity of a small particle of diameter ‘Dp’ at a distance ‘r’ from the rotational axis of a cyclone rotating at an angular speed ‘ω’ is given by (the other symbols are as per standard notation) ?

Related Mcqs:

1. A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ρL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is δ and no cake is formed. The initial pressure drop during filtration is ___________________?

   A. ½w2 . R2 . ρL
   B. ½w2 . δ2 . ρL
   C. ½w2 . δρL (2R + δ)
   D. ½w2 . R . ρL(R + 2δ)

2. Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle)?

   A. 6.V/D.S
   B. V/6D.S
   C. D.S/V
   D. V/D.S

3. Theoretical capacity of crushing rolls in tons/hr is given by (where, V = peripheral velocity, m/sec. W = width of rolls, m Dr = distance between rolls ρ = density of material to be crushed, kg/m3 here, V =πND where, N = speed of the rolls in rotation per second (rps) D = diameter of rolls, m) ?

   A. 3.6 V.W.Dr.ρ
   B. 3.6 V.W. ρ
   C. 3.6 W.Dr.ρ
   D. 3.6 V.W.Dr/ρ

4. At low Reynold’s number, the power (P) required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied: Po = ρ/ρN3 D5: Power number Re = ρ N D2/μ: Reynold’s number N is the impeller rotational speed, and D is the impeller diameter ?

   A. Po ∝ Re-1.0
   B. Po ∝ Re0.0
   C. Po ∝ Re0.5
   D. Po ∝ Re1.0

5. Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity ?

   A. Sphere
   B. Cube
   C. Cylinder (L/D = 1)
   D. Raschig rings

6. For a cyclone of diameter 0.2 m with a tangential velocity of 15 m/s at the wall, the separation factor is__________________?

   A. 2250
   B. 1125
   C. 460
   D. 230

7. The power number for a stirred tank becomes constant at high Reynolds number. In this limit, the variation of power input with impeller rotational speed (N) is proportional to___________________?

   A. N°
   B. N1
   C. N2
   D. N3

8. Equivalent diameter of a particle is the diameter of the sphere having the same __________________?

   A. Ratio of surface to volume as the actual volume
   B. Ratio of volume to surface as the particle
   C. Volume as the particle
   D. None of these

9. Which of the following agitators having a large blade area, rotating at slow speed is used for mixing high viscosity liquids (> 50000 centipoise) ?

   A. Propeller
   B. Helical screw
   C. Flat blade turbine
   D. Curved blade turbine

10. The specific surface of spherical particles is given by (where D and ρ are diameter and density of particle) ?

    A. 6/D.ρ
    B. 2/D.ρ
    C. 4/D.ρ
    D. 12/D.ρ