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

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

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

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

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

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

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

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

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

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