Packed towers vs. plate (tray) towers – choose the correct statement Considering corrosion, foaming tendency, and pressure drop, which of the following statements is correct?

Introduction / Context:
Absorption, stripping, and distillation columns are commonly built either with trays (plates) or with packing. The selection depends on pressure drop, turndown, fouling, corrosion, and foaming. Knowing typical trends helps with cost and operability decisions early in design.

Given Data / Assumptions:

• Same duty and separation difficulty.
• Comparable column diameter and materials options.
• General industry practice (not niche exceptions).

Concept / Approach:
For highly corrosive services, packed towers often win because corrosion-resistant random or structured packings (ceramic, plastics) and simple internals can be cheaper and easier than fabricating many corrosion-resistant trays. For foaming tendencies, trays are actually preferred because foam can flood packings; tray hydraulics handle foam better. Regarding pressure drop, packed towers typically offer lower pressure drop than tray columns for the same duty, one reason they are preferred in vacuum service.

Step-by-Step Solution:

Verification / Alternative check:
Vendor data and design texts show structured packing with pressure drop on the order of a few mm H2O/m vs. trays at tens of mm H2O per tray.

Why Other Options Are Wrong:

• (a) Reversed: corrosion-resistant packings simplify construction.
• (b) Reversed: foaming liquids favor trays.
• (c) Reversed: pressure drop is lower with packing.

Common Pitfalls:
Generalizing a special-case experience; always check foaming and vacuum constraints before choosing internals.

Final Answer:
none of these