In a constant
pressure cake filtration with an in-compressible cake layer, volume of the
filtrate (V) is measured as a function of time t. The plot of t/V versus V
results in a straight line with an intercept of 104 s m-3.
Area of the filter is 0.05 m2, viscosity of the filtrate is 10-3
Pa s, and the overall pressure drop across the filter is 200 KPa. The value of
the filter-medium resistance (in m-1) is
(A)
1×109
(B)
1×1011
(C)
1×1012
(D)
1×1010
GATE 2020
Answer: (B)
A
rigid spherical particle undergoes free settling in a liquid of density 750 kg
m-3 and viscosity 9.81×10-3 Pa s. Density of the particle
is 3000 kg m-3 and the particle diameter is 2×10-4 m.
Acceleration due to gravity is 9.81 ms-2. Assuming stokes’ law to be
valid, the terminal settling velocity (in m s-1) of the particle is
(E)
4×10-3
(F)
3×10-3
(G)
2×10-3
(H)
5×10-3
GATE 2020
Answer: (D)
Consider a
cylinder (diameter D and length D), a sphere (diameter D) and a cube (side
length D). Which of the following statements concerning the sphericity (ф) of
the above objects is true:
GATE 2019
Answer: (A)
A disk turbine is used to stir a liquid
in a baffled tank. To design the agitator, experiments are performed in a lab
scale model with a turbine diameter of 0.05 m and a turbine impeller speed of
600 rpm. The liquid viscosity is 0.001 Pa s while the liquid density is 1000
kg/m3. The actual application has a turbine diameter of 0.5 m, an
impeller speed of 600 rpm, a liquid viscosity of 0.1 Pa s and a liquid density
of 1000 kg/m3. The effect to gravity is negligible. If the power
required in the lab –scale model is P1 and the estimated power for
the actual application is P2, then the ratio P2/P1
is
(A)
103
(B)
104
(C)
105
(D)
106
GATE
2019
Answer: (C)
The terminal
velocity of spherical particle in gravitational settling under Stokes’ regime
varies
(A) Linearly with the particle diameter
(B) Linearly with the viscosity of the liquid
(C) Directly with the square of particle
diameter
(D) Inversely with the density of particle
GATE
2018
Answer: C
Critical speed
of a ball mill depends on
(A) The radius of the mill (shell) and the
radius of the particles
(B) The radius of the mill (shell) and the
density of the particles
(C) The radius of the balls and the radius of
the particles
(D) The radius of the balls and the radius of
the mill (shell)
GATE 2018
Answer: D
Match the equipment in Column A
with the corresponding process in Column B
|
Column
A |
Column
B |
|
(P)
Centrifugal sifter |
(I)
Mixing |
|
(Q)
Ball mill |
(II)
Sedimentation |
|
(R)
Gravity thickener |
(III)
screening |
|
(S)
Two-arm kneader |
(IV)
Grinding |
(A)
P-I, Q-IV, R-II, S-III
(B)
P-III, Q-IV, R-II, S-I
(C) P-IV, Q-I,
R-II, S-III
(D) P-IV, Q-III,
R-I, S-II
GATE
2018
Answer:
B
In
a roll crusher, rolls of diameter 1 m each are set in such a manner that
minimum clearance between the crushing surfaces is 15 mm. if the angle of nip
is 31°, the maximum diameter of the particle (in mm) which can be crushed is
___________ (rounded off to three decimal places).
GATE
2018
Answer:
53.3
Which
of the following is the correct sequence of equipment for size reduction of
solids?
GATE
2017
Answer:
D
Size
analysis was carried out on a sample of gravel. The data for mass fraction (xi)
and average particle diameter (Dpi) of the fraction is given in the
table below:
|
Xi |
0.2 |
0.4 |
0.4 |
|
Dpi (mm) |
5 |
10 |
20 |
The
mass mean diameter of the sample, to the nearest integer, is _____ mm.
GATE
2017
Answer:
13
In
a cyclone separator used for separation of solid particles from a dust laden
gas, the separation factor is defined as the ratio of the centrifugal force to
the gravitational force acting on the particle. Sr denotes the
separation factor at a location (near the wall) that is at a radial distance r
from the centre of the cyclone. Which one of the following statements is
INCORRECT?
(A)
Sr depends on mass of the
particle
(B)
Sr depends on the
acceleration due to gravity
(C)
Sr depends on tangential
velocity of the particle
(D)
Sr depends on the radial
location (r) of the particle
GATE
2016
Answer:
(A)
A vertical cylindrical vessel has a
layer of kerosene (of density 800 kg/m3) over a layer of water (of density
1000 kg/m3). L -shaped glass tubes are connected to the column 30 cm
apart. The interface between the two layers lies between the two points at
which the L-tubes are connected. The levels (in cm) to which the liquids rise
in the respective tubes are shown in the figure below.
The distance (x in cm,
rounded off to the first decimal place) of the interface from the point at
which the lower L-tube is connected is _______.
GATE
2016
Answer:
10
A typical batch
filtration cycle consists of filtration followed by washing. One such
filtration unit operating at constant pressure difference first filters a
slurry during which 5 liters of filtrate is collected in 100 s. this is
followed by washing, which is done for tw seconds and uses 1 liter
of wash water. Assume the following relation to be applicable between the
applied pressure drop ΔP, cake thickness L at time t, and volume of liquid V
collected in time t:
ΔP/L = k1 dV/dt L=k2V, if L is
changing
K1
and k2 can be taken to be constant during filtration and washing.
The wash time tw, in seconds (up to one decimal place), is
_____________.
GATE
2015
Answer:
40
The
diameter of sand particles in a sample range from 50 to 150 microns. The number
of particles of diameter x in the sample is proportional to 1/(50+x). The
average diameter in microns (up to one decimal place) is _______.
GATE 2015
Answer:
94.3
In order to
produce fine solid particles between 5 and 10 µm, the appropriate size reducing
equipment is
(A)
Fluid energy mill
(B)
Hammer mill
(C)
Jaw crusher
(D)
smooth roll crusher
GATE
2014
Answer:
(A)
Slurries are
most conveniently pumped by a
(A)
Syringe pump
(B)
Diaphragm pump
(C)
Vacuum pump
(D)
gear pump
GATE 2014
Answer: (B)
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