Falling film evaporators are used in conventional evaporators except for the mechanism for evaporation in each stage is of different unit.

Are these statements about the gasketed plate-and-frame evaporators true? Statement 1: Gasketed plate-and-frame evaporators are not used for heat sensitive materials. Statement 2: These systems are operated as rising-film, falling-film evaporators.

A

True, False

B

True, True

C

False, True

D

False, False

Climbing film evaporators are _________ falling film evaporators.

A

Better than

B

Have more efficiency than

C

Not as good as

D

Considered over

Falling film evaporators are considered over climbing film evaporators because of which one of the following factor?

A

Efficiency

B

Product holdup

C

Driving force requirement

D

Temperature sensitivity

Falling film evaporators are those in which evaporation takes place from the film interface with nucleate boiling at the wall.

A

True

B

False

The applications of falling film and rising film are more or less same, but if industries have the cost capital, they go for falling film, why?

A

It has high temperature gradient and natural convection

B

Better efficiency of falling film

C

It has less temperature gradient and natural convection

D

No need for upward pressure

Falling film evaporators can be used with the fluid falling over (i) Plates (ii) Coils (iii) Horizontal tubes (iv) Vertical tubes

A

(i)(ii)(iii)

B

(i)(ii)

C

(i)(iii)(iv)

D

(i)(ii)(iii)(iv)

Falling film evaporators are a subclass of long tube evaporators.

A

True

B

False

How are the tube surfaces in falling film evaporators heated to enhance evaporation?

A

Heaters at about 200℃

B

Heaters at above 200℃

C

Heaters at just above 100℃

D

Steam condensing at the outer wall

Statements : All film stars are playback singers. All film directors are film stars.

Conclusions :
I. All film directors are playback singers.
II. Some film stars are film directors.

A

Only conclusion I follows

B

Only conclusion II follows

C

Either I or II follows

D

Neither I nor II follows

E

Both I and II follow

Steam economy is defined as the amount of evaporation per unit amount of steam used, while the capacity is the total evaporation obtained per hour. Use of multiple effect in evaporation

A

Increases capacity

B

Increases economy

C

Does not affect the capacity

D

Both B & C

Falling film evaporators are used in conventional evaporators except for the mechanism for evaporation in each stage is of different unit.

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