Gas–liquid absorption (co-current packed tower): Which factors influence the pressure drop through the packed section?

Introduction / Context:
Pressure drop in packed absorbers affects blower or compressor power, operating costs, and capacity. Understanding how packing properties and operating conditions influence pressure drop guides both design and troubleshooting of gas–liquid contactors.

Given Data / Assumptions:

• Co-current or counter-current principles apply similarly for the packing region behavior.
• Non-reactive absorption, typical industrial packings.
• Flooding and loading concepts are relevant.

Concept / Approach:
Ergun-type correlations and generalized pressure-drop charts (e.g., Sherwood–Lobo–Eckert) show pressure drop depends on packing geometry and specific surface, fluid properties (density, viscosity, surface tension), and superficial velocities or mass fluxes of both phases. Approach to loading/flooding increases holdup and friction, raising pressure drop sharply.

Step-by-Step Reasoning:

Verification / Alternative check:
Generalized pressure-drop charts collapse data across packings using dimensionless groups (e.g., F-factor), confirming multivariable dependence consistent with (a)–(c).

Why Other Options Are Wrong:

• Any single-factor choice underrepresents the multivariate nature of pressure drop.
• “None of these” contradicts well-established correlations.

Common Pitfalls:
Extrapolating vendor data beyond recommended loading, ignoring liquid distribution quality (maldistribution can spike local holdup and pressure drop), and overlooking fouling which effectively changes packing geometry.

Final Answer:
All (a), (b) and (c)