Distillation Column Sizing Calculator for Construction

Calculator

Responsive layout: 3 columns on large screens, 2 on smaller, 1 on mobile.

Column internals

Impacts height model and typical K defaults.

Vapor flow input

Choose the most reliable data source available.

Vapor volumetric flow, Qv

m³/s

At operating conditions in the active section.

Liquid density, ρL

kg/m³

Vapor density, ρV

kg/m³

Provide measured/estimated value for better accuracy.

Surface tension, σ

mN/m

Used for a mild K correction.

Base capacity factor, K0

m/s

Typical: trays 0.10-0.13, packing 0.15-0.30.

System factor

Accounts for foaming, entrainment, uncertainties.

Design fraction of flooding

Common range: 0.70-0.85.

Diameter margin

%

Adds allowance for internals and turndown.

Rounding increment

m

Rounds up to a practical shop size.

Theoretical stages

Used to estimate tray count or packing height.

Tray efficiency

%

Actual trays = ceil(N_theor / efficiency).

Tray spacing

m

Common values: 0.45-0.75 m.

Top allowance

m

Mist eliminator, disengagement, nozzle space.

Bottom allowance

m

Sump, reboiler return, maintenance access.

ΔP per tray (optional)

kPa

Used only for an informational ΔP estimate.

Reset

Educational estimator: verify with vendor data, hydraulics, and project standards.

Formula used

The diameter estimate is based on a capacity (flooding) velocity check using a Souders-Brown style relationship:

V_flood = K_adj × √((ρL − ρV) / ρV)
V_design = f × V_flood
A = Qv / V_design
D = √(4A / π)

Where K_adj is adjusted by a system factor and a mild surface-tension correction:

K_adj = K0 × (System Factor) × (σ / 20)^0.2

K0 is highly dependent on internals and service; use vendor or in-house references when available.

How to use this calculator

Choose Trays or Packing based on your internals.
Select a vapor flow basis and enter the best available data.
Enter densities and surface tension at operating conditions.
Set K0, system factor, and flooding fraction to match your design basis.
Provide stages and allowances to estimate column height.
Click Calculate, then export CSV or PDF if needed.

Example data table

Case	Internals	Qv (m³/s)	ρV (kg/m³)	ρL (kg/m³)	Rounded D (m)	Example height (m)
Medium duty	Trays	3.0	4.0	850	1.95	20.30
High vapor	Trays	5.0	3.0	780	2.45	31.10
Low pressure	Packing	2.5	2.0	900	1.10	14.30

Example heights use: trays (N=20, eff=70%, spacing=0.6 m), trays (N=30, eff=65%, spacing=0.6 m), packing (N=18, HETP=0.6 m), plus 1.5 m top and 2.0 m bottom allowances.

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