Distillation Tray Flooding & Weeping Calculator

Calculate Souders-Brown sieve tray vapor flooding velocity, operating percent flood, Fair weep limit, and hydrodynamic operating envelope.

Column Geometry & Tray Parameters

Column Inside Diameter (ft):

Tray Spacing (in):

Active Area % of Column:

Hole Area % of Active:

Fluid Physical Properties & Flow Rates

Vapor Flow Rate (lb/hr):

Liquid Flow Rate (lb/hr):

Vapor ρ (lb/ft³):

Liquid ρ (lb/ft³):

σ (dyne/cm):

Hydrodynamic Evaluation

Percent Jet Flooding

--%

Normal Operation (65-82%)

Flood Velocity (uflood)

-- ft/s

Souders-Brown Limit

Operating Velocity (ua)

-- ft/s

Active Net Area

Flow Parameter (Flv): --

Capacity Factor (Csb): --

Hole Vapor Velocity (uh): -- ft/s

Min Weep Velocity (umin): -- ft/s

Sieve tray operating above minimum weeping threshold; liquid is supported by vapor kinetic energy.

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Frequently Asked Questions

What is tray jet flooding versus downcomer backup flooding?

Jet flooding (entrainment flood) occurs when excessive upward vapor velocity atomizes and lifts liquid droplets up to the tray above, choking the column. Downcomer backup flooding occurs when liquid head in the downcomer exceeds the tray spacing due to high liquid rates or downcomer restriction.

Why is sieve tray weeping harmful to fractionation?

Weeping occurs when vapor velocity through the tray perforations is insufficient to support the liquid pool. Instead of flowing across the tray into the downcomer, liquid rains down directly through the holes, bypassing vapor contact and devastating separation stage efficiency.

What is the optimal percent flood design range for commercial towers?

Most distillation columns are designed for 75% to 82% of flooding velocity at normal design flow. This provides adequate headroom for 15-20% process surges and feed fluctuations while ensuring the column does not weep during 60% minimum turndown operation.