In
the Tyler standard screen scale series, when the mesh number increases from 3
mesh to 10 mesh, then
(A)
The clear opening decreases
(B)
The clear opening increases
(C) The clear opening is unchanged
(D)
The wire diameter increases
GATE 2013
Answer: (A)
Taking
the acceleration due to gravity to be 10 m/s2, the separation factor
of a cyclone 0.5 m in diameter and having a tangential velocity of 20 m/s near
the wall is ___________.
GATE
2013
Answer:
160
100
ton/h of a rock feed, of which 80% passed through a mesh size of 2.54 mm, were
reduced in size such that 80% of the crushed product passed through a mesh size
of 1.27 mm. The power consumption was 100 kW. If 100 ton/h of the same material
is similarly crushed from a mesh size of 5.08 mm to a mesh size of 2.54 mm, the
power consumption (in kW, to the nearest integer) using Bond’s law, is
__________.
GATE
2013
Answer:
70.7 ton/h
The
particle size distributions of the feed and collected solids (sampled for same
duration) for a gas cyclone are given below.
|
Size range (µm) |
1-5 |
5-10 |
10-15 |
15-20 |
20-25 |
25-30 |
|
Weight of feed in the size range
(g) |
2.0 |
3.0 |
5.0 |
6.0 |
3.0 |
1.0 |
|
Weight of collected solids in the
size range (g) |
0.1 |
0.7 |
3.6 |
5.5 |
2.9 |
1.0 |
What is the collection efficiency (in
PERCENTAGE) of the gas cyclone?
(A)
31
(B)
60
(C)
65
(D)
69
GATE
2011
Answer:
(D)
The
critical speed (revolutions per unit time) of a ball mill of radius R, which
uses balls of radius r, is
GATE
2010
Answer:
(D)
The
power required for size reduction in crushing is
GATE
2008
Answer:
(C)
For laminar flow
conditions, the relationship between the pressure drop (ΔPc) across
an incompressible filter cake and the specific surface area (S0) of
the particles being filtered is given by ONE of the following
(A)
ΔPc is proportional to S0
(B)
ΔPc is proportional to 1/S0
(C)
ΔPc is proportional to S02
(D)
ΔPc is proportional to 1/S02
GATE
2008
Answer:
(C)
Consider
the scale-up of a cylindrical baffled
vessel configured to have the standard geometry (i.e. height = diameter). In
order to maintain an equal rate of mass transfer under turbulent conditions for
a Newtonian fluid, the ratio of the agitator speeds should be (given N1,
D1 are agitator speed and vessel diameter before scale-up; N2,
D2 are agitator speed and vessel diameter after scale-up)
GATE
2008
Answer:
(D)
Two
identically sized spherical particles A and B having densities ρA
and ρB respectively, are settling in a fluid of density ρ. Assuming
free settling under turbulent flow conditions, the ratio of the terminal
settling velocity of particle A to that of particle B is given by
GATE 2008
Answer:
(A)
In Tyler series,
the ratio of the aperture size of a screen to that of the next smaller screen
is
GATE
2007
Answer:
(B)
Size reduction
of coarse hard solids using a crusher is accomplished by
(A)
Attrition
(B)
Compression
(C)
Cutting
(D)
Impact
GATE 2007
Answer:
(B)
In constant
pressure filtration, the rate of filtration follows the relation (v: filtrate
volume, t: time, k and c: constants).
GATE 2007
Answer:
(B)
Sticky materials
are transported by
(A)
Apron conveyor
(B)
Screw conveyor
(C)
Belt conveyor
(D)
Hydraulic conveyor
GATE 2007
Answer:
(B)
A
filtration is conducted at constant pressure to recover solids from dilute
slurry. To reduce the time of filtration, the solids concentration in the feed
slurry is increased by evaporating half the solvent. If the resistance of the
filter medium is negligible, the filtration time will be reduced by a factor of
(A) 1
(B) 2
(C) 4
(D) 8
GATE
2006
Answer: (C)
Common Statement for next
two questions
A
continuous grinder obeying the Bond crushing law grinds a solid at the rate of 1000
kg/hr from the initial diameter of 10 mm to the final diameter of 1 mm.
If
the market now demands particles of size 0.5 mm, the output rate of the grinder
(in kg/hr) for the same power input would be reduced to
(A) 227
(B) 474
(C) 623
(D) 856
GATE
2006
Answer: (C)
In
order to restore the output back to 1000 kg/hr, an additional grinder was
installed. The two grinders can be operated either in series (configuration-1)
or parallel (configuration-2). Compare the two configurations in terms of the
additional power consumption over the case above.
(A) Configuration-1 consumes less power than
configuration-2
(B) Configuration-2 consumes less power than
configuration-1
(C) Both configurations consume the same
power
(D) Configuration-2 consumes less or more
power than configuration-1 depending on how the feed is distributed between the
two grinders in configuration-2 (the parallel configuration)
GATE 2006
Answer: (C)
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