Drying/ Humidification

Question 1

The vapor pressure exerted by the moisture contained in a wet solid depends upon the

Answer 1

Nature of the moisture
Temperature
Nature of the solid
ALL OF THE ABOVE

Question 2

To remove all the moisture from a wet solid requires exposure to

Answer 2

Perfectly dry air

Question 3

Milk is dried usually in a

Answer 3

Spray dryer

Question 4

Equilibrium-moisture curves of different solids

Answer 4

are different

Question 5

Detergent solution is dried to a powder in a

Answer 5

Spray dryer

Question 6

If moisture content of a solid on a dry basis is X then the same on wet basis is

Answer 6

X/(X+1)

Question 7

In paper industry, paper is dried in

Answer 7

Heated cylinder dryer

Question 8

Moisture content of a substance when at equilibrium with a given partial pressure of the vapor is called

Answer 8

Equilibrium moisture

Question 9

Calcium ammonium nitrate (fertilizer) is dried in a

Answer 9

Rotary dryer

Question 10

Moisture in a substance exerting an equilibrium vapor pressure LESS than that of pure liquid at the same temperature is

Answer 10

Bound moisture

Question 11

Rotary dryer cannot handle

Answer 11

Sticky materials

Question 12

Moisture in a solid exerting an equilibrium vapor pressure EQUAL to that of the pure liquid at the same temperature is

Answer 12

Unbound moisture

Question 13

Refractory bricks are usually dried in a

Answer 13

Tunnel dryer

Question 14

Heat sensitive materials like certain pharmaceuticals and food stuff can be dried

Answer 14

By freeze drying

Question 15

Moisture contained by a substance in excess of the equilibrium moisture is called

Answer 15

Free moisture

Question 16

Flights in a rotary dryer are provided to

Answer 16

lift and shower the solids thus exposing it thoroughly to the drying action of the gas

Question 17

In the constant rate period of the rate of drying curve for batch drying

Answer 17

Surface evaporation of unbound moisture occurs

Question 18

The falling rate period in the drying of a solid is characterized by

Answer 18

Increasing temperatures both on the surface and within the solids

Question 19

Dryer widely used in a textile industry is

Answer 19

Festoon dryer

Question 20

Sticky material can be dried in a

Answer 20

Tray dryer

Question 21

Drying of a solids involves

Answer 21

Both heat and mass transfer

Question 22

A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process

Answer 22

temperature of the solid

Question 23

Capacity of a rotary dryer depends on

Answer 23

its rpm
its inclination with ground surface

Question 24

Air at a particular humidity is heated in a furnace. The new dew point

Answer 24

Increases

Question 25

The critical moisture content in case if drying indicates

Answer 25

Beginning of falling rate period

Question 26

A slurry is to be dried to produce flaky solid. Which dryer would you recommend?

Answer 26

Spray dryer

Question 27

For continuous drying of granular or crystalline material, the dryer used is

Answer 27

Rotary

Question 28

All moisture in a non-hygroscopic material is … moisture

Answer 28

Unbound

Question 29

During constant rate period, the rate of drying decreases with

Answer 29

decrease in air temperature
increase air humidity