A. Facilitate draining out liquid from a tray when the unit is not in operation
B. Are normally located near the overflow weir so that any delivery of liquid during operation
follows approximately the same path as the overflow fluid
C. Must be large enough (usually 1/4″ to 5/8″ dia) to prevent plugging but should not deliver
excessive amount of fluid during operation
D. All A., B. and C.
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 - 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. - An adequate clearance between the tray and the shell wall of a distillation column is provided to_____________________?
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 - In sieve plate column, holes are drilled or punched in sizes ranging from 2.5 to 12 mm (5 mm being widely used). The hole pitch is normally ______________ times the hole diameter to give the required hole area?
A. 0.5 to 1.5
B. 2.5 to 4.0
C. 5 to 10
D. 10 to 15 - In packed towers provided with pall rings liquid redistributors are positioned at heights of every 6 metres or 5-10 times the column diameter, whichever is less. Maximum size of the pall rings should not exceed _______________________ of the column diameter?
A. 1/10-1/15th
B. 1/5-1/10th
C. 1/20-1/30th
D. 1/2 to 1/4th - The thickness of heat transfer plates used in the plate type heat exchanger ranges from _____________ mm, pressed in a single piece provided with grooves & corrugations?
A. 0.3 to 0.8
B. 1.25 to 3.125
C. 3.5 to 7.0
D. 8 to12 - Bubble cap diameter used for the distillation column having diameter ranging from 1.5 to 4.5 metres is about ______________ mm?
A. 10
B. 50
C. 100
D. 200 - Which of the following factors determine the amount of entrainment in a distillation column ?
A. Plate spacing
B. Depth of liquid above the bubble cap slots
C. Vapour velocity in the volume between the plates
D. All A., B. and C. - 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 - Pick out the wrong statement pertaining to the design of the distillation column?
A. Generally, a skirt clearance of 0.5″ to 1.5′ is recommended to prevent plugging of the slots by
residue build up
B. The purpose of the slot is to disperse the gas into the liquid in the form of small bubbles
C. If sufficient slot area is not provided, the gas may pass through the skirt clearance
D. None of these
