Tower internals and packing/tray practice: identify the incorrect statement among common sizing guidelines for columns and trays.

Introduction / Context:
Distillation column internals are sized using a blend of hydraulic limits, mechanical constraints, and practical fabrication limits. Rules-of-thumb guide preliminary choices for cap sizes, packing heights, and sieve tray hole diameters before detailed rating is performed. Recognizing incorrect statements helps avoid operability problems like weeping, excessive entrainment, or high pressure drop.

Given Data / Assumptions:

• Conventional hydrocarbon or aqueous service.
• Standard materials and fabrication methods.
• Focus on preliminary guidelines, not vendor-specific exceptions.

Concept / Approach:
Sieve trays require a minimum hole diameter sufficiently larger than the plate thickness to ensure proper jet formation and to avoid weeping/plugging. A typical practice is hole diameter roughly 1.5–2.5 times the tray thickness (material-dependent). Equating hole diameter to the plate thickness is far below practical limits and leads to poor performance.

Step-by-Step Solution:

Verification / Alternative check:
Open literature and vendor guidance specify minimum hole diameters exceeding plate thickness; undersized holes promote weeping and fabrication difficulties.

Why Other Options Are Wrong (brief appraisal):

• (a) and (b) describe common preliminary selections.
• (d) is a material-specific rule seen in some conservative practices; regardless, (c) is unequivocally incorrect.

Common Pitfalls:
Assuming one-size-fits-all rules; ignoring material differences (carbon steel vs. stainless); neglecting fouling and corrosion margins when choosing hole sizes.

Final Answer:
In a sieve tray, the minimum hole diameter equals the tray thickness.