Operating velocity in a packed tower is usually __________________ the flooding velocity ?

Related Mcqs:

1. At the same gas flow rate, the pressure drop in a packed tower being irrigated with liquid _______________ that in dry packed tower ?

   A. Is greater than
   B. Is lower than
   C. Is same as
   D. Cannot be predicted as data are insufficient

2. Under conditions of flooding in packed tower, the gas pressure drop___________________?

   A. Decreases rapidly
   B. Increases rapidly
   C. Remain constant
   D. Is maximum

3. The reason for preferring packed towers over plate towers in distillation practice is that the packed tower operation gives___________________?

   A. Low pressure drop and high hold up
   B. High pressure drop and low hold up
   C. Low pressure drop and low hold up
   D. High pressure drop and high hold up

4. Pressure drop through plate tower as compared to that through packed tower, for the same duty will be___________________?

   A. Less
   B. More
   C. Equal
   D. Either A. or B.; depends on the packing height

5. In a moderately sized packed absorption tower, channelling (which is most severe with stacked packings) can be minimised by taking the ratio of tower diameter to packing diameter ?

   A. > 4 :1
   B. < 8 : 1
   C. > 8:1
   D. < 6:1

6. A packed tower compared to a plate tower for a particular mass transfer operation__________________?

   A. Incurs smaller pressure drop
   B. Allows installation of cooling coils
   C. Is less costly when built in large sizes/diameters
   D. Is more suitable, if suspended solids are present in fluid streams

7. In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalent to a theoretical plate HTUOG = overall gas phase height of a transfer unit) ?

   A. Straight
   B. Parallel
   C. Both A. & B.
   D. Neither A. nor B.

8. In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG ______________ the absorption factor?

   A. Increases with increase in
   B. Is one at unity value of
   C. Both A. and B.
   D. Neither A. nor B.

9. In an absorption column, the flooding velocity for random packing is ___________________ that for stacked/regular packing?

   A. Greater than
   B. Smaller than
   C. Equal to
   D. Either A., or B.; depends on the type of packing

10. For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, FG: mass transfer co-efficient, moles/m2, a: interfacial area per unit volume of tower) ?

    A. G/(FG . a)
    B. FG/(G . a)
    C. (G . a)/FG
    D. L/(FG . G)