A minimum clearance of about __________ mm is maintained between the distillation column wall and the bubble cap.

In a distillation column, minimum clearance to be maintained betweeen the overflow weir and the last row of the bubble caps is __________ cms.

A

2.5

B

7.5

C

15

D

20

With decrease in the throughput (compared with the design capacity) for a bubble cap distillation column, its efficiency

A

Increases

B

Decreases

C

Remains same

D

May increase or decrease ; depends on individual design

Bubble cap tray is the most commonly used tray in large distillation column, because

A

Of its flexibility and nearly constant efficiency under varying conditions of operation

B

It incurs less pressure drop as compared to any other try designed for the same duty

C

It eliminates the foaming and entrain-ment tendency during operation

D

None of these

An adequate clearance between the tray and the shell wall of a distillation column is provided to

A

Drain the liquid from the tray when the unit is not in operation

B

Allow for thermal expansion and facilitate installation

C

Avoid back-trapping

D

None of these

In actual operation of a bubble cap distillation tower, the __________ at the bottom of the tower is more than that at the top of the tower.

A

Molal flow rate of vapour

B

Vapour molecular weight

C

Pressure and temperature

D

All of the above

For a given design of bubble cap, the number of bubble caps to be used per tray is set by the

A

Allowable gas velocity through the slots

B

Plate spacing

C

Diameter of the column

D

All of the above

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

In a distillation column, bubble caps are located on trays with a pitch of __________ times the outside diameter of the caps.

A

1.3 to 2

B

1.6 to 2

C

2.5

D

1.5 to 3

Bubble cap plate column is

A

A finite stage contactor

B

Used only for distillation, not for absorption

C

A differential stage contactor

D

A continuous contactor

Typical static submergence for bubble cap plate column operating at atmospheric pressure may be around

A

2.5"

B

0.5"

C

5"

D

50% of the plate spacing

A minimum clearance of about __________ mm is maintained between the distillation column wall and the bubble cap.

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