A. Plate efficiency increases with increase in superficial vapour velocity till entrainment limit
B. Increase in depth of the liquid about the slots increases the plate efficiency, particularly if the liquid depth is < 1"
C. Too small a plate spacing can cause a low efficiency, if the vapour velocity is greater than the allowable value
D. None of these
Related Mcqs:
- Pick out the wrong statement?
A. If sufficient residence time (around 8 seconds) is not provided to the downcoming liquid in
the downcomer, it may entrain some vapour
B. The liquid head in the downcomer should not be greater than one half the plate spacing to
avoid flooding
C. The discharge end of the downcomer must project far enough into the tray liquid so that no
gas bubbles can enter the open end and by pass the bubble caps
D. None of these - Pick out the wrong statement pertaining to shell and tube heat exchanger_______________?
A. Clearance between shell & baffles and between tube & baffles should be minimum to avoid
by-passing of the fluid, but it should be enough to permit the removal of tube bundle
B. Baffles are supported independently of the tubes by tie rods and positioned by spacers
C. Tie rods are fixed at one end in the tube sheet by making blind holes and the minimum
number of tie rods is 4 with at least 10 mm diameter
D. Bracket supports are used for horizontal shell, while saddle support is used for vertical shell - Pick out the wrong statement?
A. Riveting provides a permanent fastening method
B. The joint made by overlapping of one plate over the other, and then riveting the two plates together with two rows of rivets is called ‘double riveted butt joint’
C. Shank diameter of the rivets should be less than the size of the hole drilled in the plate for riveting
D. The efficiency of a riveted joint is the ratio of the strength of the riveted joint to the strength of the solid plate - 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 - Pick out the wrong statement. In an agitated vertical cylindrical reaction vessel, the___________________?
A. Ratio of liquid depth to tank diameter (i.e. the filling ratio) recommended for most purposes is 1
B. Filling ratio for dispersing gas in a liquid is 2 for sufficiently long contact period
C. Flat bottom and conical bottom vessels have low agitation efficiency for agitation of heavy solids in liquids
D. Dished bottom vessel has very high power consumption - 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 comparative evaluation of performance of the packed tower and the plate tower ?
A. Plate tower is preferred, if interstage cooling is required to remove heats of reaction or
solution
B. Plate tower is preferred over packed tower, if the operation involves liquids containing
dispersed solids
C. The total weight of a dry plate tower is usually much more than that of a dry packed tower
designed for the same duty
D. In operations involving large temperature changes. (e.g. distillation), plate towers are
preferred over packed towers as the packing may be crushed due to large temperature changes - Pick out the wrong statement?
A. Safety valves are provided in heat exchangers for removal of non-condensable
B. Liquid metals and Dowtherm are used for very high temperature heating
C. In a shell and tube heat exchanger, high pressure fluid is generally routed through the tube
D. A loop seal or U-seal is provided in a vertical condenser sub-cooler to prevent quick draining
of the condensate - Pick out the wrong statement about routing of fluids in a shell and tube heat exchanger ?
A. The corrosive and fouling fluid should be preferably routed through the tubes
B. The viscous fluid should be routed through the shell side
C. Lower flow rate fluid should be routed through the shell side
D. Higher pressure fluid stream should be routed through the shell side - 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
