ChemCalc provides a complete suite for distillation column design and rating, from binary VLE and shortcut methods through detailed tray and packed-column hydraulics. All calculations run in-browser with no installation required.
Available Distillation Modules
FUG shortcut method McCabe-Thiele graphical stages Sieve tray hydraulics (9-check) Random packing (GPDC) Structured packing (Mellapak/FlexiPac/BX) Preliminary column summary Sensitivity analysisFUG Shortcut Method
| Step | Method | Output |
|---|---|---|
| Minimum stages | Fenske equation | N_min at total reflux |
| Minimum reflux | Underwood equation | R_min for q-line feed |
| Actual stages | Gilliland correlation | N_theor at operating R |
| Feed stage | Kirkbride equation | Optimal feed tray location |
Sieve Tray Hydraulics — 9-Check Audit
Based on Fair (1961) flood correlation and Kister "Distillation Design" (1992) Ch. 6:
| Check | Criterion |
|---|---|
| Flood fraction | Ua / Uflood ≤ 80% (Fair Csb) |
| Downcomer backup | Hdc ≤ 50% tray spacing |
| Downcomer choke | Velocity in DC < 0.12 m/s |
| Weeping guard | Ua ≥ 40% flood (Fair heuristic) |
| Hole velocity | Vh ≥ minimum to prevent weep |
| System limit | Stupin-Kister capacity check |
| Pressure drop | Dry tray + liquid head + residual |
| Entrainment | Fair fractional entrainment e/L |
| Residence time | DC liquid residence ≥ 3 s |
Packed Column Rating
Supports random packings (Raschig rings, Pall rings, IMTP, Cascade Mini-Rings, Nutter rings — GPDC correlation from Strigle 1994) and structured packings (Sulzer Mellapak 250/350/500/750, MellapakPlus, BX, CY; Koch FlexiPac; Raschig Super-Pak — Spiegel-Meier 1992 capacity model).
VLE Thermodynamics
Distillation modules integrate with ChemCalc's VLE engine: Peng-Robinson or SRK EOS for high-pressure service, and NRTL gamma-Raoult for 17 verified binary pairs at low pressure (ethanol-water, acetone-water, benzene-cyclohexane, and more).