A. Distillation under vacuum is a substitute for steam distillation
B. In differential (simple) distillation, the vapour is removed as soon as it is formed without appreciable condensation
C. In flash (equilibrium) distillation, a definite fraction of liquid is vaporised in such a way that the evolved vapour & residual liquids are in equilibrium with each other
D. Flash distillation, differential distillation & steam distillation are all continuous distillation processes
Related Mcqs:
- 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 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 - Pick out the wrong statement?
A. The tensile strength of a brittle material is less than its compressive strength
B. The compressive strength of a ductile material is less than its tensile strength
C. In a thick cylindrical shell, the hoop stress is maximum at the inner radius
D. The value of crushing load is more than that of buckling load for long columns - 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
