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


  • Options
  • A. ½w2 . R2 . ?L
  • B. ½w2 . ?2 . ?L
  • C. ½w2 . ??L (2R + ?)
  • D. ½w2 . R . ?L(R + 2?)

  • Correct Answer
  • ½w2 . ??L (2R + ?) 


  • Mechanical Operations problems


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    • 1. Solid particles of different densities are separated by

    • Options
    • A. filters
    • B. thickness
    • C. cyclones
    • D. sorting classifier
    • Discuss
    • 2. Optimum ratio of operating speed to critical speed of a trommel is

    • Options
    • A. 0.33-0.45
    • B. 1.33-1.45
    • C. 0.5-2
    • D. 1.5-2.5
    • Discuss
    • 3. Filtration rate through a filter cake is proportional to (where, S = filtering surface R = specific cake resistance ? = viscosity of the filtrate)

    • Options
    • A. S
    • B. 1/R
    • C. 1/?
    • D. all (a), (b) & (c)
    • Discuss
    • 4. Which of the following is the softest material?

    • Options
    • A. Talc
    • B. Feldspar
    • C. Corundum
    • D. Calcite
    • Discuss
    • 5. A fluid energy mill is used for

    • Options
    • A. cutting
    • B. grinding
    • C. ultra grinding
    • D. crushing
    • Discuss
    • 6. Dry powdery solid materials are transported by a __________ conveyor.

    • Options
    • A. belt
    • B. bucket
    • C. screw
    • D. none of these
    • Discuss
    • 7. In a roll crusher, both the rolls

    • Options
    • A. have the same diameter.
    • B. are rotated towards each other.
    • C. run either at the same or different speeds.
    • D. all (a), (b) and (c).
    • Discuss
    • 8. What is the critical rotation speed in revolutions per second, for a ball mill of 1.2 m diameter charged with 70 mm dia balls?

    • Options
    • A. 0.5
    • B. 1.0
    • C. 2.76
    • D. 0.66
    • Discuss
    • 9. The cake resistance increases steadily with the time of filtration in a plate and frame filter employing constant __________ filtration.

    • Options
    • A. rate
    • B. pressure
    • C. both (a) & (b)
    • D. neither (a) nor (b)
    • Discuss
    • 10. As particle size is reduced

    • Options
    • A. screening becomes progressively more difficult.
    • B. screening becomes progressively easier.
    • C. capacity and effectiveness of the screen is increased.
    • D. none of these.
    • Discuss


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