Chemical Engineering:: Process Equipment and Plant Design

To keep the power input constant for a stirred vessel operating under fully developed turbulent flow conditions (constant power number), if the impeller diameter is increased by 20%, the impeller speed should be decreased by a factor of

A. (1.2)3/2
B. (1.2)3/5
C (1.2)2/3
D. (1.2)5/3

Speed of the drum of the rotary vacuum filter normally ranges from __________ rpm.

A. 0.1 to 2
B. 5 to 7
C 3 to 8
D. 8 to 15

A stuffing box is used for

A. absorbing the contraction/expansion of pipeline due to temperature changes.
B. prevention of fluid leakage around moving parts.
C facilitating smooth opening and closing of a valve.
D. reducing the resistance of fluid flow.

Pick out the wrong statement. In an agitated vertical cylinderical reaction vessel, the

A. ratio of liquid depth to tank diameter (i.e. the filling ratio) recommended for most purposes is 1.
B. filling ratio for dispersing gas in a liquid is 2 for sufficiently long contact period.
C flat bottom and conical bottom vessels have low agitation efficiency for agitation of heavy solids in liquids.
D. dished bottom vessel has very high power consumption.

Pick out the wrong statement pertaining to the design of the bubble cap tray of a distillation column to give stable operation and even vapour distribution.

A. The pressure drop due to the caps & slots and the static submergence should be as high as practicable for reasonable operation.
B. Tendency towards stable operation is increased by increasing the skirt clearance of the caps, lowering the rate of liquid flow per unit plate width or increasing the spacing between the caps.
C The dimensionless ratio of liquid gradient to pressure drop head caused by the bubble cap assembly should be less than 0.4.
D. none of these.

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