Tray columns: under which flow pattern is the maximum plate (stage) efficiency generally achieved?

Introduction / Context:
Plate (Murphree) efficiency in tray columns reflects the degree of approach to equilibrium on a given tray. Hydraulics and contacting patterns strongly influence efficiency. Different tray layouts—cross, reverse, or split flow—change liquid path lengths and vapor–liquid contacting times, impacting mass transfer and backmixing.

Given Data / Assumptions:

• Conventional tray internals with outlet weirs and downcomers.
• Comparable vapor and liquid loadings for fair comparison.
• Interest in relative efficiency potential of common patterns.

Concept / Approach:
Reverse-flow trays route liquid across nearly the full tray active area, often yielding longer liquid path and improved contacting with rising vapor. This tends to increase tray efficiency compared to simpler cross-flow arrangements that may have shorter paths or more non-ideal zones. Split-flow trays divide liquid into parallel paths; they can reduce path length and may lower efficiency relative to well-designed reverse flow (though they can reduce tray pressure drop and handle higher capacities).

Step-by-Step Solution:

Verification / Alternative check:
Design literature indicates reverse-flow trays can reach higher efficiencies given comparable hydraulics, though exact values depend on system properties and tray details.

Why Other Options Are Wrong:

• Cross flow and split flow often trade some efficiency for capacity/operability.
• “Cascade” is not a standard tray-flow category for general efficiency comparison.

Common Pitfalls:
Ignoring weeping, entrainment, and froth behavior; assuming efficiency gains without verifying hydraulics and pressure drop.

Final Answer:
Reverse flow