# Fluidization Engineering Questions and Answers – Minimum Fluidizing Velocity

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This set of Fluidization Engineering online test focuses on “Minimum Fluidizing Velocity”.

1. Fluidization occurs when: Drag force by the upward moving gas ________
a) Weight of the particle
b) Weight of the fluid
c) Volume of the bed
d) Pressure drop across bed

Explanation: Drag force by the upward moving gas = Weight of the particle.

2. What is the range of Reynolds number(Re) for small particles in the fluidization bed?
a) Re < 20
b) Re > 20
c) 20 < Re > 1000
d) 20 > Re < 1000

Explanation: Since smaller particles require less velocity of gas to lift the particles, hence the Re is low.

3. What is the range of Reynolds number(Re) for small particles in the fluidization bed?
a) Re < 20
b) Re > 20
c) Re > 1000
d) 20 > Re < 1000

Explanation: Since larger particles require large velocity of gas to lift the particles, hence the Re is large.

4. Fluidization expression is compared with which equation from fluid mechanics?
a) Euler’s equation
b) Bernoulli’s equation
c) Buoyancy equation
d) Navier–Stokes equation

Explanation: Because the Euler’s equation is analogous to Fluidization equation.

5. Minimum Fluidizing equation can be expressed in terms of which physical quantity?
a) Pressure drop
b) Temperature
c) Velocity
d) Volume

Explanation: Since pressure drop is required to find the exact velocity of gas required to keep the particles floating.

6. What is the sphericity of sharp sand particles?
a) 0.67
b) 0.86
c) 0.63
d) 0.58

Explanation: Based on the data from the Voidage table at Minimum fluidizing conditions.

7. What is the sphericity of round sand particles?
a) 0.67
b) 0.86
c) 0.63
d) 0.58

Explanation: Based on the data from the Voidage table at Minimum fluidizing conditions.

8. What is the sphericity of anthracite coal particles?
a) 0.67
b) 0.86
c) 0.63
d) 0.58

Explanation: Based on the data from the Voidage table at Minimum fluidizing conditions.

9. What is the sphericity of Fisher-catalyst particles?
a) 0.67
b) 0.86
c) 0.63
d) 0.58

Explanation: Based on the data from the Voidage table at Minimum fluidizing conditions.

10. On comparison with Fluidized bed and Packed bed, which has the highest voidage?
a) Fluidized bed
b) Packed bed
c) Pressure drop
d) All of the mentioned 