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
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 - Pick out the wrong statement about the design of a sieve plate column ?
A. An increased weir height improves the tray efficiency at the cost of high plate pressure drop; optimum wear height being 40-90 mm for column pressure above atmospheric and 6-12 mm for vacuum columns
B. For segmental downcomers, the chord length is 60-80% of the column diameter. An initial value of downcomer area of 12% is taken in the design
C. Width of the calming section provided at the inlet and outlet sides of the plate is 75 mm for column diameter below 1.5 metres and 100 mm for larger diameter columns
D. Minimum recommended downcomer residence time for the disengagement of entrained vapour is the same for both foaming and non-foaming liquids, which is about 20 seconds - 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 - For a given design of bubble cap, the number of bubble caps to be used per tray is set by the _________________?
A. Allowable gas velocity through the slots
B. Plate spacing
C. Diameter of the column
D. All A., B. and C. - In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about _______________ cms?
A. 10
B. 20
C. 30
D. 35 - Bubble cap plate column is___________________?
A. A finite stage contactor
B. Used only for distillation, not for absorption
C. A differential stage contactor
D. A continuous contactor - Typical static submergence for bubble cap plate column operating at atmospheric pressure may be around _________________?
A. 2.5″
B. 0.5″
C. 5″
D. 50% of the plate spacing - In common bubble cap distillation column design practice, riser area is approximately equal to (where, Aa = Annular passage area, and Sa = Slot area) ?
A. Aa = Sa
B. 1.2 Aa = 1.2 Sa
C. Sa = 1.5 Aa
D. Aa = 1.5 Sa - In the allocated cap area, bubble caps are generally arranged on equilateral triangular pitch. Number of caps fixed on a plate is with a __________________?
A. Clearance of 25-75 mm
B. Cap pitch of 1.3-2 times the cap diameter
C. Either A. or B.
D. Neither A. nor B. - 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
