Engineering Questions with Answers - Multiple Choice Questions

Separation Processes MCQ’s – Drying Equipments-2

1 - Question

Why direct heating by hot air cannot be done in some cases?
a) The material can degrade
b) High temperature not required
c) Low temperature not required
d) Conduction gives best results

View Answer

Answer: a
Explanation: Since some materials are thermally degradable, direct heating techniques cannot be employed.




2 - Question

When are drum dryers used?
a) When the material is too thick for spray dryer and too thin for rotary dryer
b) When the material is too thick for rotary dryer and too thin for spray dryer
c) When the material is not biodegradable
d) When large crystal size is to be obtained

View Answer

Answer: a
Explanation: Drum dryers are used when the material is too thick for spray dryer and too thin for rotary dryer.




3 - Question

How is heating achieved in drum dryers?
a) By heating the drums
b) By conduction
c) By passing steam through hollow screws
d) By passing steam through the conveyer belt

View Answer

Answer: c
Explanation: Heating is achieved in the drum dryers by passing heat through the hollow screws.




4 - Question

What is the drum dryer called if it is open to the atmosphere?
a) Open dryer
b) Box dryer
c) Trough dryer
d) Trench dryer

View Answer

Answer: c
Explanation: When a drum dryer is open to the atmosphere it is called as trough dryer.




5 - Question

Which materials are not used in drying in a freeze dryer?
a) Seafood
b) Fruits
c) Pharmaceuticals
d) Dyes

View Answer

Answer: d
Explanation: Dyes are not used to dry in freeze dryer.




6 - Question

How the liquid does gets separated in freeze dryer?
a) Boiling
b) Distillation
c) Freezing and crystallization
d) Evaporation

View Answer

Answer: c
Explanation: The material is first frozen so that the liquid gets frozen and is separated as crystals.




7 - Question

Heat sensitive or easily oxidizable materials are dried by:
a) Flash dryer
b) Drum dryer
c) Fluidized bed dryer
d) Rotary dryer

View Answer

Answer: a
Explanation: Since the contact time is less the flash dryer can be used to dry heat sensitive or easily oxidizable materials.




8 - Question

With what is the feed introduced in the spary dryer?
a) Spray
b) Atomizer
c) Nucleator
d) Heat exchanger

View Answer

Answer: b
Explanation: A spray dryer is used to dry the atomized droplets of a feed that may be
a solution or a slurry of fine particles. It consists of a big drying chamber in which the feed is introduced through an atomizer at the top.




9 - Question

What is the use of a high pressure nozzle or a whirling disk in a spray dryer?
a) Increasing contact time
b) Decreasing contact time
c) Agitation
d) Atomization

View Answer

Answer: d
Explanation: Atomization is done by a high pressure nozzle or a whirling disk.




10 - Question

Which dryer used radiation for drying?
a) Spray dryer
b) Drum dryer
c) Flash dryer
d) Microwave dryer

View Answer

Answer: d
Explanation: A microwave dryer uses long wavelength radiation of the order of radio waves.
The material is heated throughout by the radiation that penetrates into it.

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