A. Drain the liquid from the tray when the unit is not in operation
B. Allow for thermal expansion and facilitate installation
C. Avoid back-trapping
D. None of these
Related Mcqs:
- 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 - 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 - 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 - A minimum clearance of about _______________ mm is maintained between the distillation column wall and the bubble cap?
A. 19
B. 38
C. 67
D. 95 - In a distillation column, minimum clearance to be maintained between the overflow weir and the last row of the bubble caps is ______________ cms?
A. 2.5
B. 7.5
C. 15
D. 20 - The function of manholes provided in the shell of a distillation column is to __________________?
A. Keep a check on the liquid gradient over the plate by direct visual observation
B. Give access to the individual trays for cleaning, maintenance and installation
C. Guard against foaming & entrainment by dumping antifoaming agent through it
D. All A., B. and C. - _____________________ tray arrangement is recommended for distillation column having diameter upto 4 ft ?
A. Radial flow
B. Cross flow
C. Split flow
D. Cascade - The minimum tray spacing in distillation column of diameter less than 3 ft is normally _____________ inches?
A. 6
B. 18
C. 24
D. 34 - Pressure drop per tray in the atmospheric distillation column is about ________________ psi?
A. 0.01 – 0.5
B. 0.07 – 0.12
C. 0.5 – 1.0
D. 1 – 3 - Overall tray efficiency of a distillation column is the ratio of the number of ___________________?
A. Overall gas transfer units to the number of ideal trays required
B. Ideal trays required to the number of real trays required
C. Real trays required to the number of ideal trays required
D. None of these
