Questions and answers for exam Preparation

MCQs

Total Questions : 1628 | Page 9 of 163 pages

Question 81. In a rotary drier, the average retention time of solid is(where Z = length of the drier, metres ρ = apparent solid density, kg/m³ L = flow rate of dry solids, kg/see. m² drier cross-section H = hold up of solid.)

Z.H.ρ/L
L/Z.H.ρ
H.ρ/L
Z.H/L.ρ

Discuss Question

Answer: Option A. -> Z.H.ρ/L

Question 82. The most common standard size of bubble caps used in industrial operation is

1" dia cap with 0.5" dia riser
6" dia cap with 4" dia riser
8" dia cap with 1" dia riser
4" dia cap with 8" dia riser

Discuss Question

Answer: Option B. -> 6" dia cap with 4" dia riser

Question 83. The circumferential (hoop) stress in a thin walled cylinderical vessel under internal pressure is

pd/2t
pd/4t
pd/t
pd/3t

Discuss Question

Answer: Option A. -> pd/2t

Question 84. The longitudinal stress induced in a thin walled cylinderical vessel under internal pressure is

pd/2t
pd/4t
pd/t
pd/8t

Discuss Question

Answer: Option B. -> pd/4t

Question 85. In case of design of a shell and tube heat exchanger,

Minimum cleaning lane of 6.5 mm is provided, when tubes are on a square pitch
Minimum tube sheet thickness (in which tubes are fixed) is equal to the O.D. of the tube upto 15 mm tube diameter; and for > 15 mm tube diameter, tube sheet thickness is smaller than tube diameter
O.D. of the tube is 6 to 40 mm while the tube lengths used are 0.5, 2.5, 3.0, 4.0, 5.0, 6 metres
All of the above

Discuss Question

Answer: Option D. -> All of the above

Question 86. Pick out the wrong statement about routing of fluids in a shell and tube heat exchanger.

The corrosive and fouling fluid should be preferably routed through the tubes
The viscous fluid should be routed through the shell side
Lower flow rate fluid should be routed through the shell side
Higher pressure fluid stream should be routed through the shell side

Discuss Question

Answer: Option D. -> Higher pressure fluid stream should be routed through the shell side

Question 87. Pick out the wrong statement pertaining to a shell and tube heat exchanger.

The minimum value of baffle spacing is 50 mm
The maximum value of baffle spacing is equal to the I.D. of the shell
The maximum unsupported tube span is generally about 75 times tube diameter, but is reduced to about 60 times for aluminium, copper & alloys of these
Disk and doughnut baffle is the most commonly used baffle

Discuss Question

Answer: Option D. -> Disk and doughnut baffle is the most commonly used baffle

Question 88. Pick out the wrong statement pertaining to shell and tube heat exchanger.

Clearance between shell & baffles and between tube & baffles should be minimum to avoid by-passing of the fluid, but it should be enough to permit the removal of tube bundle
Baffles are supported independently of the tubes by tie rods and positioned by spacers
Tie rods are fixed at one end in the tube sheet by making blind holes and the minimum number of tie rods is 4 with at least 10 mm diameter
Bracket supports are used for horizontal shell, while saddle support is used for vertical shell

Discuss Question

Answer: Option D. -> Bracket supports are used for horizontal shell, while saddle support is used for vertical shell

Question 89. In case of a shell and tube heat exchanger, the effect of L/D on inside film heat transfer co-efficient (hi) vanishes after a Reynold number of