This set of Mechanical Operations Multiple Choice Questions & Answers (MCQs) focuses on “Separation of Solid by Screening”.
1. In a continuous thickener, the area is determined by the _____
a) Commination layer
b) Newton layer
c) Plank layer
d) Concentration layer
View Answer
Explanation: In case of a continuous layer, the area is determined by that concentration layer for which solids handling capacity is per unit time minimum.
2. What does the following equation represents?
Q (1 – C)
a) Feed rate
b) Evaporation rate
c) Drying rate
d) Pull over rate
View Answer
Explanation: The liquid feed rate is given by the above equation for a thickener, where Q is the volumetric flow and C is the concentration.
3. Calculate the feed rate, if the volumetric flow is 55 m3/s and concentration is 0.5?
a) 27.5
b) 3.5
c) 55
d) 50
View Answer
Explanation: As we know feed rate = Q (1 – C) = 55(1-0.5) = 27.5.
4. What does the following equation represents?
p (1-C)
a) Feed rate
b) Evaporation rate
c) Mass rate
d) Pull over rate
View Answer
Explanation: The mass feed rate is given by the above equation for a thickener, where p is the density of fluid in kg/m3 and C is the concentration.
5. Calculate the feed rate, if the density of fluid is 78.9 kg/m3 and concentration is 0.03?
a) 76.53
b) 75.5
c) 50.2
d) 1.33
View Answer
Explanation: As we know mass feed rate = p (1 – C) = 78.9 (1-0.03) = 76.533.
6. To obtain largest throughput, rate of sedimentation should be _____
a) Same
b) High
c) Low
d) Constant
View Answer
Explanation: In order to obtain the highest throughput from a thickener, the rate of sedimentation should be as high as possible.
7. Cone scrapers are bolted to ______
a) Bottom End
b) Centre shaft
c) Back valve
d) Dirt separator
View Answer
Explanation: Cone scrapers are bolted to the center shaft to prevent plugging of the bottom discharge cone.
8. What are the size of centered column thickener?
a) 75 ft. in diameter
b) 55 ft. in diameter
c) < or = 75 ft. in diameter
d) < or = 55 ft. in diameter
View Answer
Explanation: They are usually 75 ft. in diameter and in special cases they may be smaller, Lifting devices will lift the raking arms 12 to 36 inches.
9. For a tray thickener, feed enters a ____
a) Exchanger
b) Splitter
c) Driver
d) Separator
View Answer
Explanation: Feed enters a feed splitter box at the top of the tank which divides the flow amongst the compartments of the thickener.
10. ______ is defined as the distance from the liquid from top to bottom.
a) Extrapolation
b) Superposition
c) Superelevation
d) Evenpolation
View Answer
Explanation: Superelevation is defined as the distance from the liquid level in the top compartment to the level in the overflow pipeline.
Sanfoundry Global Education & Learning Series – Mechanical Operations.
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