Bissoy
Login
Get Advice on Live Video Call
Earn $ Cash $ with
consultations on Bissoy App
A gas (density = 1.5 kg/m<sup>3</sup>, viscosity = 2 × 10<sup>-5</sup> kg/m.s) flowing through a packed bed (particle size = 0.5 cm, porosity = 0.5) at a superficial velocity of 2 m/s causes a pressure drop of 8400 Pa/m. The pressure drop for another gas, with density of 1.5 kg/m<sup>3</sup> and viscosity of 3 × 10<sup>-5</sup> kg/m.s flowing at 3 m/s will be
A
8400 Pa/m
B
12600 Pa/m
C
18900 Pa/m
D
16800 Pa/m
Correct Answer:
12600 Pa/m
A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun's equation for the above fluid-particle system (in SI units) is given below:
Δ P/L = 375 × 10
3
V
OM
+ 10.94 × 10
6
V
2
OM
(SI units)
If water is to be used as the fluidising medium, in actual operation, the above bed has a height = 1 m. What is the porosity of the fluidised bed?
A
0.2
B
0.5
C
0.7
D
0.8
A fully packed bed with small particle size has _________ pressure drop than a bed with larger particle size.
A
More
B
Less
C
Same
D
Negligible
For Laminar flow through a packed bed, the pressure drop is proportional to (V
s
is the superficial liquid velocity and D
p
is the particle diameter)
A
$$\frac{{{{\text{V}}_{\text{s}}}}}{{{{\text{D}}_{\text{p}}}^2}}$$
B
$$\frac{{{{\text{V}}_{\text{s}}}^2}}{{{{\text{D}}_{\text{p}}}^2}}$$
C
$$\frac{{{{\text{V}}_{\text{s}}}^2}}{{{{\text{D}}_{\text{p}}}^3}}$$
D
$$\frac{{{{\text{V}}_{\text{s}}}}}{{{{\text{D}}_{\text{p}}}^3}}$$
For liquid flow through a packed bed, the superficial velocity as compared to average velocity through the channel in the bed is
A
More
B
Less
C
Equal
D
Independent of porosity
A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun's equation for the above fluid-particle system (in SI units) is given below :
Δ P/L = 375 x 10
3
V
OM
+ 10.94 x 10
6
V
2
OM
(SI units)
If water is to be used as the fluidising medium, the minimum fluidisation velocity, V
OM
is
A
12 mm/s
B
16 mm/s
C
24 mm/s
D
28 mm/s
Bed pressure drop in an air fluidised bed of catalyst particles (ρ
p
= 200 kg/m
3
, D
p
= 0.05 cm) of 60 cm bed depth and bed porosity of 0.5 expressed in cm of water (manometer) is
A
90
B
60
C
45
D
30
A bed consists of particles of density 2000 kg/m
3
. If the height of the bed is 1.5 metres and its porosity 0.6, the pressure drop required to fluidise the bed by air is
A
25.61 kPa
B
11.77 kPa
C
14.86 kPa
D
21.13 kPa
Smaller sized packings are generally dumped to the packed columns, and the large ones of size greater than __________ mm are stacked individually, which provides better control over bed porosity and offers lower gas pressure drop.
A
25
B
50
C
75
D
150
For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, F
G
: mass transfer co-efficient, mols/m
2
, a: in-terfacial area per unit volume of tower)
A
$$\frac{{\text{G}}}{{{{\text{F}}_{\text{G}}}.{\text{a}}}}$$
B
$$\frac{{{{\text{F}}_{\text{G}}}}}{{{\text{G}}{\text{.a}}}}$$
C
$$\frac{{{\text{G}}{\text{.a}}}}{{{{\text{F}}_{\text{G}}}}}$$
D
$$\frac{{\text{L}}}{{{{\text{F}}_{\text{G}}}.{\text{G}}}}$$
The pressure drop per unit length of pipe incurred by a fluid 'X' flowing through pipe is $$\Delta {\text{p}}.$$ If another fluid 'Y' having both the specific gravity & density just double of that of fluid 'X', flows through the same pipe at the same flow rate/average velocity, then the pressure drop in this case will be
A
$$\Delta {\text{p}}$$
B
$$2\Delta {\text{p}}$$
C
$$\Delta {{\text{p}}^2}$$
D
$$\frac{{\Delta {\text{p}}}}{2}$$