Cyclone separators — pressure drop effect:\nFor a given particle size distribution, how does increasing the pressure drop across a cyclone affect its dust collection efficiency?

Introduction / Context:
Cyclone separators remove particulates by imparting tangential velocity, generating centrifugal forces that drive particles to the wall for collection. Hydraulic resistance (pressure drop) reflects the intensity of swirl and gas acceleration, both of which influence separation performance.

Given Data / Assumptions:

• Particle size distribution fixed; gas properties and cyclone geometry constant.
• Pressure drop increase is achieved by higher inlet velocity or design tuning.
• Operation away from extreme fouling or severe re-entrainment.

Concept / Approach:
Collection efficiency correlates with the particle cut size d50, which decreases as tangential velocity and residence time increase. Higher inlet velocity raises centrifugal acceleration a_c ≈ v_θ^2 / r, improving the likelihood that particles overcome turbulent diffusion and are collected, at the cost of higher pressure drop.

Step-by-Step Reasoning:

Verification / Alternative check:
Empirical correlations (e.g., Stairmand, Lapple) show efficiency rising with velocity (and thus ΔP), barring excessive erosion or re-entrainment at very high loads.

Why Other Options Are Wrong:

• Decrease/Unaffected: contradict observed dependence on swirl intensity.
• Unpredictable based only on dust chemistry: geometry and hydrodynamics dominate.
• Zero due to re-entrainment: re-entrainment can occur at extremes, but not the general trend.

Common Pitfalls:
Ignoring power costs and erosion at higher ΔP; not accounting for parallel cyclones to limit velocity while meeting efficiency.

Final Answer:
Increase