Particulate control devices – Working principle of a cyclone separator: The operating principle of a cyclone dust collector is primarily based on which action exerted on the particles?
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ADiffusion
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BCentrifugal force
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CGravitational settling only
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DElectrostatic attraction
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EBrownian motion
Answer
Correct Answer: Centrifugal force
Explanation
Introduction / Context:Cyclone separators are rugged, low-maintenance devices used to remove medium-to-coarse particles from gas streams in boilers, kilns, and process exhausts. Knowing their governing mechanism guides selection and performance prediction.
Given Data / Assumptions:
- Swirling gas flow is generated tangentially in a conical/cylindrical body.
- Particles have inertia relative to the carrier gas.
Concept / Approach:As gas swirls, particles experience an outward radial force proportional to mass, tangential velocity squared, and inversely to radius (centrifugal force). Particles migrate to the wall, lose momentum, and drop into a hopper, while cleaned gas exits near the centerline.
Step-by-Step Solution:Induce tangential entry → create vortex flow.Centrifugal force drives particles radially outward to the wall.Axial flow carries the gas upward through a vortex finder; particles fall by gravity into the dust leg.
Verification / Alternative check:Empirical grade-efficiency curves show improved capture with higher inlet velocity and larger particle size, consistent with centrifugal separation physics.
Why Other Options Are Wrong:
- Diffusion/Brownian motion: dominate for ultrafines, not the cyclone’s main mechanism.
- Gravitational settling only: gravity helps once at wall, but the key separation is centrifugal.
- Electrostatic attraction: principle of ESPs, not cyclones.
Common Pitfalls:Using cyclones for submicron particles expecting high efficiency—electrostatic precipitators or fabric filters are better for very fine dust.
Final Answer:Centrifugal force