Fluidization Engineering

Terminal Velocity of Particles

Question 1
Marks : +2 | -2
Pass Ratio : 100%
For large solid particles Reynolds number should be greater than?
10
100
1000
10000
Explanation:
Since the size of particles is large, the velocity will be comparatively large. Hence the range also increases.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
When the diameter is narrower of the bed, which kind of problem is most likely to occur in the bed?
Chanelling
Slugging
Entrainment
None of the mentioned
Explanation:
Slugging occurs due to coagulation of air bubbles without breaking.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
What is the range of Ut/Umf for flexible operation of the fluidized bed?
10:1 to 90:1
5:1 to 10:1
90:1 to 120:1
120:1 to 200:1
Explanation:
This range provides best conditions for fluidization without much entrainment.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
What is the Reynolds number range when the drag coefficient formula is 10/(Rep)^0.5?
Rep < 0.4
0.4 < Rep < 500
500 < Rep < 200,000
None of the mentioned
Explanation:
Range is taken based on the experimental values.
Question 5
Marks : +2 | -2
Pass Ratio : 100%
When the bed is just fluidized the height attained is maximum, true or false?
True
False
Explanation:
Because after that height, the further increase in velocity will definitely lead to entrainment of some particles.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
What is the Reynolds number range when the drag coefficient formula is 24/(Rep)?
Rep < 0.4
0.4 < Rep < 500
500 < Rep < 200,000
None of the mentioned
Explanation:
Range is taken based on the experimental values.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
For fine solids Reynolds number should be less than?
0.4
4
40
400
Explanation:
Since the size of particles is small, the velocity will be comparatively small. Hence the range also reduces.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
What can be done in order to prevent slugging in the fluidized bed?
Baffles
Increase diameter
Proper design of distributor
All of the mentioned
Explanation:
Placing baffles will break the bubbles, increasing the diameter will reduce chances of slugging, distributor design also decides the slugging factor.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
The velocity of fluid is operated between minimum fluidizing velocity(Umf) and Pneumatic velocity in fluidized bed, true or false?
True
False
Explanation:
It is operated between minimum fluidizing velocity and terminal velocity(Ut) in fluidized bed.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
What is the Reynolds number range when the drag coefficient formula is 0.43?
Rep < 0.4
0.4 < Rep < 500
500 < Rep < 200,000
None of the mentioned
Explanation:
Range is taken based on the experimental values.