Typical pressure drop per tray: in an atmospheric distillation column, what is the approximate pressure drop across a single tray, expressed in psi?

Introduction / Context:
Knowing the typical pressure drop per tray helps in estimating overall column pressure profile, condenser duty, and potential vacuum limitations. Atmospheric columns are designed to keep per-tray pressure drops modest to prevent excessive cumulative losses over many stages.

Given Data / Assumptions:

• Atmospheric operation (near 1 atm at the top).
• Conventional tray types and normal vapor/liquid loadings.
• Pressure drop requested in psi per tray.

Concept / Approach:
Empirical design practice places per-tray pressure drop in a relatively small band. For many atmospheric services, pressure drop of roughly 0.07–0.12 psi per tray is typical, balancing sufficient vapor–liquid contact with reasonable column height and energy use. Much higher drops are more typical of high-pressure or high-capacity services and would be undesirable at atmospheric conditions.

Step-by-Step Solution:

Verification / Alternative check:
Rules-of-thumb in distillation design texts list comparable ranges for atmospheric columns.

Why Other Options Are Wrong:

• 0.01–0.5 is too broad; 0.01 psi is unrealistically low and 0.5 psi is too high for typical atmospheric operation.
• 0.5–1.0 and 1–3 psi are characteristic of much heavier services and would cause undue total pressure loss.
• 3–5 is far above normal.

Common Pitfalls:
Confusing mm H2O or inches of water with psi; not accounting for tray type and loading effects.

Final Answer:
0.07 – 0.12