Introduction to drying

Why direct heating by hot air cannot be done in some cases?

• The material can degrade

• High temperature not required

• Low temperature not required

• Conduction gives best results

When are drum dryers used?

• When the material is too thick for spray dryer and too thin for rotary dryer

• When the material is too thick for rotary dryer and too thin for spray dryer

• When the material is not biodegradable

• When large crystal size is to be obtained

How is heating achieved in drum dryers?

• By heating the drums

• By conduction

• By passing steam through hollow screws

• By passing steam through the conveyer belt

What is the drum dryer called if it is open to the atmosphere?

• Open dryer

• Box dryer

• Trough dryer

• Trench dryer

Which materials are not used in drying in a freeze dryer?

• Seafood

• Fruits

• Pharmaceuticals

• Dyes

How the liquid does gets separated in freeze dryer?

• Evaporation

• Freezing and crystallization

• Distillation

• Boiling

Heat sensitive or easily oxidizable materials are dried by:

• Flash dryer

• Drum dryer

• Fluidized bed dryer

• Rotary dryer

With what is the feed introduced in the spary dryer?

• Spray

• Atomizer

• Nucleator

• Heat exchanger

What is the use of a high pressure nozzle or a whirling disk in a spray dryer?

• Increasing contact time

• Decreasing contact time

• Agitation

• Atomization

Which dryer used radiation for drying?

• Spray dryer

• Drum dryer

• Flash dryer

• Microwave dryer