Which of the following air pollution-control/particle-collection devices uses the force of gravity to aid in the collection of particles by exploiting their terminal velocity?

Correct option is B

1. Elutriators and Gravity:
· Elutriators utilize terminal velocity and the force of gravity to separate particles from a gas stream.
· The principle involves allowing the particles to settle due to gravity when the upward flow of gas becomes slow enough for particles to fall.
· This process is highly effective for size-based separation of particles.
2. Explanation of Other Options:
· Electrostatic precipitators: Use an electric field to charge particles and then collect them on oppositely charged plates, not relying on gravity.
· Bag houses: Utilize fabric filters to capture particulate matter by filtration mechanisms.
· Super saturators: Enhance particle collection by using condensation methods rather than gravity or terminal velocity.
Elutriators specifically rely on gravitational settling by exploiting the terminal velocity of particles, making them unique among the options listed.
Information Booster: 1. Types of Particle Collection Devices:
· Gravity-based: Elutriators and settling chambers.
· Filtration-based: Bag houses and HEPA filters.
· Electrostatic: Electrostatic precipitators.
· Condensation-based: Super saturators and wet scrubbers.
2. Elutriation Process:
· Gas flows upward through a chamber at a controlled velocity.
· Particles with higher settling velocities fall out due to gravity, while finer particles remain suspended.
3. Advantages of Elutriators:
· Simple design and operation.
· Low cost compared to other particle collection devices.
4. Limitations:
· Ineffective for very fine particles.
· Often requires additional filtration systems for complete air pollution control.