Chemical Engineering MCQs

Pick out the wrong statement about distillation operation

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Distillation under vacuum is a substitute for steam distillation.
In differential (simple) distillation, the vapour is removed as soon as it is formed without appreciable condensation.
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.
Flash distillation, differential distillation & steam distillation are all continuous distillation processes.
✅ The correct answer is option D.

An increase in the liquid resistance to interphase mass transfer and a resultant reduction in plate efficiency is caused by

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an increase in liquid viscosity.
an increase in relatived volatility for rectification columns.
decrease in gas solubility for absorbers.
all (a), (b) and (c).
✅ The correct answer is option D.

Bubble cap tray is the most commonly used tray in large distillation column, because

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of its flexibility and nearly constant efficiency under varying conditions of operation.
it incurs less pressure drop as compared to any other try designed for the same duty.
it eliminates the foaming and entrain-ment tendency during operation.
none of these.
✅ The correct answer is option A.

Pick out the wrong statement pertaining to ‘Horton sphere’ used for the storage of liquid ammonia.

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Diameter of Horton sphere is normally 6 to 25 metres and it is supported by 6 to 12 nos. tubular or rolled section column.
Thickness of spherical shell is half that of the cylinderical vessel under same operating pressure condition. Besides, the ratio of surface area to volume is less for sphere than any other shape ; hence insulation required is less.
Horton sphere is used for the storage of gases and volatile liquid at a moderate pressure of 1 to 10 kg/cm2 .
Horton sphere is used for the storage of liquid at sub-zero temperature at very high pressure upto 200 kg/cm2 .
✅ The correct answer is option D.