Maximum allowable vapour velocity in a bubble cap tower is determined by the

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

Even though bubble cap towers are very effective for humidification operation, they are not used commonly in industries, because of the

A

High evaporation losses of water

B

High pressure drop of the gas

C

Difficulty in its fabrication

D

None of these

In the allocated cap area, bubble caps are generally arranged on equilateral triangular pitch. Number of caps fixed on a plate is with a

A

Clearance of 25-75 mm

B

Cap pitch of 1.3-2 times the cap diameter

C

Either A or B

D

Neither A nor B

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 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

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

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

A

19

B

38

C

76

D

95

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 high vapour velocity is required for high plate efficiency in a seive plate coloumn. The satisfactory value of operating vapor velocity for design purpose in seive plate column is about __________ percent of the flooding velocity.

A

45

B

60

C

80

D

95

Maximum allowable vapour velocity in a bubble cap tower is determined by the

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