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
Related Mcqs:
- A high vapour velocity is required for high plate efficiency in a sieve plate column. The satisfactory value of operating vapor velocity for design purpose in sieve plate column is about _______________ percent of the flooding velocity?
A. 45
B. 60
C. 80
D. 95 - 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 - Holes of a sieve tray are arranged in triangular pitch of _________________ times the hole diameter?
A. 1.5 to 2
B. 2.5 to 5
C. 5 to 10
D. 10 to 15 - 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 - Pick out the wrong statement about the design of sieve plate column and the bubble cap column ?
A. The downcomer design and the residence time in the downcomer is almost same for sieve
plate and bubble cap columns
B. Weir length for a bubble cap plate is the same as that for the sieve plate
C. Weir height for a bubble cap plate column is the same as that for a sieve plate column
D. Weir height in case of a bubble cap plate ranges from 50 to 150 mm and is higher than the
sieve plate - 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 - Hole diameter of the sieve trays in the distillation column ranges from ______________ mm?
A. 1 to3
B. 4 to 8
C. 3 to 12.5
D. 12.5 to 18.5 - 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 - _____________________ tray arrangement is recommended for distillation column having diameter upto 4 ft ?
A. Radial flow
B. Cross flow
C. Split flow
D. Cascade
