Engineering Questions with Answers - Multiple Choice Questions
Mechanical Operations MCQ’s – Separation of Solid by Screening
1 - Question
In a continuous thickener, the area is determined by the _____
a) Commination layer
b) Newton layer
c) Plank layer
d) Concentration layer
View Answer
Answer: d
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 - Question
What does the following equation represents?
Q (1 – C)
a) Feed rate
b) Evaporation rate
c) Drying rate
d) Pull over rate
View Answer
Answer: a
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 - Question
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
Answer: a
Explanation: As we know feed rate = Q (1 – C) = 55(1-0.5) = 27.5.
4 - Question
What does the following equation represents?
p (1-C)
a) Feed rate
b) Evaporation rate
c) Mass rate
d) Pull over rate
View Answer
Answer: c
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 - Question
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
Answer: a
Explanation: As we know mass feed rate = p (1 – C) = 78.9 (1-0.03) = 76.533.
6 - Question
To obtain largest throughput, rate of sedimentation should be _____
a) Same
b) High
c) Low
d) Constant
View Answer
Answer: b
Explanation: In order to obtain the highest throughput from a thickener, the rate of sedimentation should be as high as possible.
7 - Question
Cone scrapers are bolted to ______
a) Bottom End
b) Centre shaft
c) Back valve
d) Dirt separator
View Answer
Answer: b
Explanation: Cone scrapers are bolted to the center shaft to prevent plugging of the bottom discharge cone.
8 - Question
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
Answer: c
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 - Question
For a tray thickener, feed enters a ____
a) Exchanger
b) Splitter
c) Driver
d) Separator
View Answer
Answer: b
Explanation: Feed enters a feed splitter box at the top of the tank which divides the flow amongst the compartments of the thickener.
10 - Question
______ is defined as the distance from the liquid from top to bottom.
a) Extrapolation
b) Superposition
c) Superelevation
d) Evenpolation
View Answer
Answer: c
Explanation: Superelevation is defined as the distance from the liquid level in the top compartment to the level in the overflow pipeline.