The maximum liquid gradient over a tray must not exceed__________________?

Related Mcqs:

1. Maximum acceptable total liquid gradient over a tray is about _______________ mm?

   A. 5.5
   B. 12.5
   C. 30.5
   D. 45.5

2. Liquid gradient over the tray results due to the___________________?

   A. Resistance offered to flow of liquids by caps & risers and the flow of gas
   B. Low gas velocity
   C. Large plate spacing
   D. Large reflux ratio

3. Excessive liquid gradient on a tray may result in the______________________?

   A. Maldistribution of gas
   B. Back trapping
   C. Gas blowing beneath cap skit
   D. All A., B. and C.

4. Liquid gradient over a tray can be minimised by________________?

   A. Providing a higher skirt clearance or a higher weir
   B. Decreasing the number of rows of caps through which the liquid flows or by decreasing the
   velocity of liquid flow past the caps or by reducing the distance along the tray through which
   the liquid must flow
   C. Using split flow, radial flow or cascade flow for column diameter large than 4 ft
   D. All A., B. and C.

5. Bubble cap tray is the most commonly used tray in large distillation column, because______________?

   A. Of its flexibility and nearly constant efficiency under varying conditions of operation
   B. It incurs less pressure drop as compared to any other try designed for the same duty
   C. It eliminates the foaming and entrainment tendency during operation
   D. None of these

6. Pick out the wrong statement pertaining to the use of valve tray, seive tray and bubble cap trays in continuous distillation column ?

   A. Bubble cap trays though most expensive are the best in situations, where low vapour rates is to be handled and a positive liquid seal is essential at all flow rates
   B. Murphree efficiency of all the three trays are nearly equal, however the peak efficiency is generally higher for sieve and valve trays than the bubble cap
   C. Maintenance cost for valve and sieve trays are comparatively more than bubble cap tray due to their relatively complicated construction features
   D. Valve trays have the highest turn down ratio (i.e. the ratio of the highest to the lowest vapour flow rates) and thus provide the maximum flexible operating range

7. Generally, as the length of the liquid path on a tray is increased beyond 5 ft, the overall column efficiency___________________?

   A. Increases
   B. Decreases
   C. Remain same
   D. May increase or decrease depending upon the plate spacing

8. _____________________ tray arrangement is recommended for distillation column having diameter upto 4 ft ?

   A. Radial flow
   B. Cross flow
   C. Split flow
   D. Cascade

9. Overall distillation column efficiency for most of the refinery columns can be given by (for μ = 0.07 – 1.4 cp and relative volatility < 4) (where ε = overall column efficiency, % μ = molal average viscosity of feed at average column temperature and pressure, cp Δp = pressure drop per tray, psi) ?

   A. η = 17 – 61.1 log μ
   B. η = 24.6 (Δp/μ)
   C. η = 1.66 – 0.25 log μ
   D. η = 0.25 log μ – 1.67

10. Diameter of the sieve tray column is determined by the_________________?

    A. Lower limit of vapour velocity
    B. Upper limit of the vapour velocity
    C. Hole diameter of the sieve tray
    D. Height of the plate spacing