This set of Separation Processes Multiple Choice Questions & Answers (MCQs) focuses on “Drying Equipments-2”.
1. 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
Explanation: Since some materials are thermally degradable, direct heating techniques cannot be employed.
2. 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
Explanation: Drum dryers are used when the material is too thick for spray dryer and too thin for rotary dryer.
3. 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
Explanation: Heating is achieved in the drum dryers by passing heat through the hollow screws.
4. 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
Explanation: When a drum dryer is open to the atmosphere it is called as trough dryer.
5. Which materials are not used in drying in a freeze dryer?
Explanation: Dyes are not used to dry in freeze dryer.
6. How the liquid does gets separated in freeze dryer?
c) Freezing and crystallization
Explanation: The material is first frozen so that the liquid gets frozen and is separated as crystals.
7. Heat sensitive or easily oxidizable materials are dried by:
a) Flash dryer
b) Drum dryer
c) Fluidized bed dryer
d) Rotary dryer
Explanation: Since the contact time is less the flash dryer can be used to dry heat sensitive or easily oxidizable materials.
8. With what is the feed introduced in the spary dryer?
d) Heat exchanger
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. 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
Explanation: Atomization is done by a high pressure nozzle or a whirling disk.
10. Which dryer used radiation for drying?
a) Spray dryer
b) Drum dryer
c) Flash dryer
d) Microwave dryer
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.
Sanfoundry Global Education & Learning Series – Separation Processes.
To practice all areas of Separation Processes, here is complete set of 1000+ Multiple Choice Questions and Answers.