Fluid-Solid Systems

This quiz contains multiple-choice problems on fluidisation and its types, characteristics of fluidised systems, the flow of solids through particles, bubbles and drops settling, fluidisation velocity, spherical particles, fluidisation applications and hindered setting.

Start Quiz

Which of the following parts of a fluidized system separates the product from air?

Filter bags Air handler High shear mixer Distributor plate

Which of the following is true about Wurster fluid system’s coating process?

Inner partition has a diameter that is approximately 30% of the coating chamber’s diameter Air distribution plate has holes drilled of equal sizes all over the plate Spray nozzle is located at the center of the plate Wurster fluid bed was designed in 1850

Which of the following happens when the gas velocity increases in fluidization?

Bulk density of the increases and fluidization become less aggressive Bulk density of the decreases and fluidization become less aggressive Bulk density of the increases and fluidization become more aggressive Bulk density of the decreases and fluidization become more aggressive

Which of the following is the best condition for minimum fluidization?

Drag force imparted by the down flowing gas equals the weight of the particles, and void space in the bed increases slightly Drag force imparted by the upward flowing gas equals the weight of the particles, and void space in the bed increases slightly Drag force imparted by the upward flowing gas equals the weight of the particles, and void space in the bed decreases slightly Drag force imparted by the down flowing gas equals the weight of the particles, and void space in the bed decreases slightly

How do solids behave like fluids in fluidization?

By blowing liquid downwards through the reactor

By blowing gas upwards through the reactor

By blowing gas or liquid downwards through the reactor

By blowing gas or liquid upwards through the reactor

When does slugging occur in fluidization?

When height of the bed is greater than diameter of the bed

When height of the bed is shorter than diameter of the bed

When height of the bed is equal to the diameter of the bed

Slugging does not depend on the ratio of height of bed and diameter of bed

Which of the following statements is false regarding the Huttlin – Kugel coater?

It does not consist of central processor

Spray nozzles cannot be located at the bottom

The product container is spherical

Fluidized air passes through the center of product container

Calculate the initial porosity of the bed, given that the void volume is 0.8901 and the total volume is 1.1.

0.9791

0.2099

1.2358

0.8092

Calculate the porosity of the bed when the initial bed height is 24.5 cm, the final bed height is 34.5 cm, and the initial porosity is 0.2036.

0.634

0.534

0.434

0.334

Water was used as the fluid in a fluidized bed. The length of the fluidization column was 1000 mm, and the manometer readings were 26 cm and 24 cm. Calculate the pressure difference per length of the column. Acceleration due to gravity is used as 9.8 m/s^2.

198 kg/m^2s^2

196 kg/m^2s^2

200 kg/m^2s^2

194 kg/m^2s^2

Which of the following statements is true regarding fluidized beds?

Intense mixing leads to non-uniform temperature

Fluidized solids can be easily transferred from one reactor to another

Heat transfer in a fluidized bed is moderate

Heat exchangers are present over the circumference of the fluidized bed

Which of the following statements is false regarding fluidized bed catalytic cracking?

It cracks longer molecules into shorter compounds

Catalytic reactions in the catalytic riser take 2-4 seconds to complete

Stacked configuration covers more space than side-to-side configuration

Carbon produced during cracking gets deposited on the catalyst

For a bed of small spherical particles that fluidizes at the rate of 1cm/s, the operating velocity should be less than which of the following? Consider porosity of the bed to 0.45.

25 cm/s

50 cm/s

40 cm/s

48 cm/s

Which of the following is the correct equation for minimum fluidization velocity for large particles? Here, D{p} is the diameter of the particle, ρ{P} and ρ{F} are the densities of particle and fluid medium respectively, ε{mf} is the porosity and Φ{S} is the shape factor.

U{mf}^2 = D{p}g((ρ{P} - ρ{F})/1.75ρF)*(ε{mf}^3)*Φ{S}

U{mf}^2 = D{p}g((ρ{P} + ρ{F})/(1.75)ρF)*(ε{mf}^3)*Φ{S}

U{mf}^2 = D{p}g((ρ{P} - ρ{F})/(1.75)ρF)*(ε{mf}^2)*Φ{S}

U{mf}^2 = D{p}g((ρ{P} + ρ{F})/(1.75)ρF)*(ε{mf}^2)*Φ{S}

A fluidized bed has small particles with Reynolds number 18 and diameter 2 mm. The fluid medium is water, and the density of the particles is 2500 kg/m^3. If we consider the viscosity of water to be 8.11 × 10-4 kg/ms, porosity of the bed to be 0.45, acceleration due to gravity to be 9.8 m/s^2 and the particles to be completely spherical, what is the minimum fluidization velocity for those particles?

0.07

0.004

0.08

0.04

Quiz/Test Summary

Title: Fluid-Solid Systems

Questions: 15

Contributed by: