Fluidization in Gas-Fluidized Beds

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What occurs in gas-fluidized beds?

Large pockets of gas, free of particles, rise through the bed (correct)

The entire bed becomes a homogenous mixture

The bed void fraction decreases significantly

Particles settle at the bottom of the bed

What is the term used to describe the condition where successive bubbles move up the column?

Particulate fluidization

Incipient fluidization

Slugging (correct)

Bubbling fluidization

What happens to the pressure drop as the superficial fluid velocity is gradually increased from zero?

It suddenly spikes

It gradually increases (correct)

It gradually decreases

It remains constant

What is the point at which the pressure drop starts to decrease?

Minimum fluidization velocity (B) Signup and view all the answers

What occurs when very dense particles are in a liquid?

Bubbling fluidization occurs (C) Signup and view all the answers

What is the term used to describe the phenomenon where gases at high pressure flow through beds of fine particles?

Particulate fluidization (C) Signup and view all the answers

What is the primary reason for fluidizing a bed of particles?

To obtain vigorous agitation of the solids in contact with the fluid (A) Signup and view all the answers

What is the term for the minimum velocity of the fluid required to fluidize a bed of particles?

Minimum fluidization velocity (C) Signup and view all the answers

What type of fluidization occurs in liquids?

Particulate fluidization (D) Signup and view all the answers

What is the primary application of fluidized beds in the petroleum industry?

Catalytic cracking (B) Signup and view all the answers

What is the benefit of using fluidized beds in highly exothermic reaction situations?

Nearly uniform temperatures (A) Signup and view all the answers

What is the purpose of fluidizing a bed of catalytic particles?

To achieve intimate contact between the particles and the fluid (A) Signup and view all the answers

What is the condition to prevent particles from being carried out with the fluid at the exit?

Superficial velocity is equal to the settling velocity of the particles (A) Signup and view all the answers

What is the range of void fraction ε for nearly spherical particles?

0.40 - 0.45 (C) Signup and view all the answers

What equation should be used to determine the minimum fluidization velocity for large particles?

Ergun equation (B) Signup and view all the answers

What is the result of combining Equations (11) and (12) and eliminating pressure drop?

Minimum fluidization velocity (D) Signup and view all the answers

What is the state of the bed when the superficial velocity Vs is equal to Vf?

Incipient fluidization (A) Signup and view all the answers

What is the ratio of the settling velocity to the minimum fluidization velocity for ε lying in the range 0.40 - 0.45?

78-50 (C) Signup and view all the answers