A. Narrow
B. Deep
C. Both A. & B.
D. Neither A. nor B.
Related Mcqs:
- 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 × 103 VOM + 10.94 × 106 V2 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 - Bed pressure drop in an air fluidised bed of catalyst particles (ρp = 200 kg/m3, Dp = 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 - Slugging in a fluidised bed can be avoided by using_____________________?
A. Tall narrow vessel
B. Deep bed of solids
C. Shallow beds of solids and proper choice of particle size
D. Very large particles - A 0.5 m high bed made up of a 1 mm dia glass sphere (density 2500 kg/m3 ) is to be fluidised by water (density 1000 kg/m3 ). If at the point of incipient fluidisation, the bed voidage is 40%, the pressure drop across the bed is________________?
A. 4.4 KPa
B. 2.94 KPa
C. 3.7 KPa
D. None of these - Pressure drop in a fluidised bed reactor is ______________ that in a similar packed bed reactor?
A. Less than
B. Greater than
C. Same as
D. None of these - A bed consists of particles of density 2000 kg/m3. 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 - In a fluidised bed reactor___________________?
A. Temperature gradients are very high
B. Temperature is more or less uniform
C. Hot spots are formed
D. Segregation of the solids occurs - The uniformity of a gas fluidised bed depends upon the _______________ of the solid particles?
A. Size
B. Surface properties
C. Both A. and B.
D. Neither A. nor B. - For laminar flow of a fluid through a packed bed of spheres of diameter d, the pressure drop per unit length of bed depends upon the sphere diameter as_________________?
A. d
B. d2
C. d4
D. d̅ 2 - 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 × 103 VOM + 10.94 × 106 V2 OM (SI units) If water is to be used as the fluidising medium, the minimum fluidisation velocity, VOM is_________________?
A. 12 mm/s
B. 16 mm/s
C. 24 mm/s
D. 28 mm/s
