In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.

What is the steam economy in case of a single effect evaporator system?

A

1

B

> 1

C

0.1

A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because

A

Total heat transfer area of all the effects is -less than that in a single effect evaporator system

B

Total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect

C

Boiling point elevation in a single effect system is much higher than that in any effect in a multieffect system

D

Heat transfer co-efficient in a single effect is much lower than that in any effect in a multieffect system

Expanding steam to a very low pressure (high vacuum) in steam engines is

A

Desirable

B

Economical

C

Essential

D

Uneconomical

Vacuum for reciprocating steam engines compared to steam turbines is

A

More

B

Equal

C

Less

D

Could be more or less depending on the size of plant

Steam economy in case of a triple effect evaporator will be

A

1

B

> 1

C

Between 0 and 1

Vacuum is applied in __________ zone, in case of a general type continuous rotary drum vacuum filter.

A

Filtering

B

Washing

C

Drying

D

All of the above

Vacuum maintained in the vacuum distillation column in oil refinery is in the range of about __________ mm Hg absolute.

A

1 to 5

B

30 to 80

C

250 to 350

D

450 to 500

The vacuum maintained in vacuum distillation unit for reduced crude is about __________ mmHg.

A

1.2

B

12

C

120

D

700

Vacuum maintained in the vacuum distillation tower of the crude distillation plant is about __________ mm Hg (absolute).

A

5-10

B

30-80

C

150-250

D

350-400

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

In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.

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