Home / Chemical Engineering / Mechanical Operations :: Section 4

Chemical Engineering :: Mechanical Operations

  1. A __________ mixer resembles a ball mill without balls.

  2. A.
    banbery
    B.
    pug mill
    C.
    tumbling
    D.
    pan

    View Answer

    Workspace

    Discuss Discuss in Forum


  3. __________ conveyor is the most suitable for short distance transportation of non-abrasive loose materials like garbage, grain, food wastes etc.

  4. A.
    Flight
    B.
    Screw
    C.
    Drag
    D.
    Belt

    View Answer

    Workspace

    Discuss Discuss in Forum


  5. As the product becomes finer, the energy required for grinding

  6. A.
    decreases
    B.
    increases
    C.
    is same as for coarser grinding
    D.
    is 1.5 times that for coarser grinding

    View Answer

    Workspace

    Discuss Discuss in Forum


  7. Gyratory crushers compared to the reciprocating jaw crushers

  8. A.
    have greater capacity per unit of discharge area.
    B.
    crush intermittantly.
    C.
    are less suitable for coarse materials.
    D.
    have less steady power consumption.

    View Answer

    Workspace

    Discuss Discuss in Forum


  9. The important dimensional group involved in the power requirement calculation in mixing operation is the __________ number.

  10. A.
    Reynold's
    B.
    Froude
    C.
    both (a) & (b)
    D.
    neither (a) nor (b)

    View Answer

    Workspace

    Discuss Discuss in Forum


  11. 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.

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

    View Answer

    Workspace

    Discuss Discuss in Forum


  13. Which of the following grinding mills has the horizontally arranged rods as the grinding elements thereby delivering more uniform granular products with minimum fines ?

  14. A.
    Compartment mill
    B.
    Rod mill
    C.
    Pebble mill
    D.
    Tube mill.

    View Answer

    Workspace

    Discuss Discuss in Forum


  15. Rittinger's crushing law states that

  16. A.
    work required to form a particle of any size is proportional to the square of the surface to volume ratio of the product.
    B.
    work required to form a particle of a particular size is proportional to the square root of the surface to volume ratio of the product.
    C.
    work required in crushing is proportional to the new surface created.
    D.
    for a given machine and feed, crushing efficiency is dependent on the size of the feed & product.

    View Answer

    Workspace

    Discuss Discuss in Forum


  17. Mechanical conveyors which push the material along an endless trough or tube are called scrappers. Which of the following conveying equipments comes under the category of 'scrappers' ?

  18. A.
    Bucket conveyor
    B.
    Flight conveyor
    C.
    Screw conveyor
    D.
    Both (b) and (c)

    View Answer

    Workspace

    Discuss Discuss in Forum


  19. Sphericity of pulverised coal is

  20. A.
    1
    B.
    <1
    C.
    >1
    D.

    View Answer

    Workspace

    Discuss Discuss in Forum