🧪 Reflux Partial Condenser Sizer (Dephlegmator)

Size vertical reflux partial condensers and dephlegmators: Hewitt & Wallis flooding limit velocity, Silver-Bell-Ghaly heat transfer, and overhead vapor enrichment.

⚡ Fortran 90 Engine Double Precision (IEEE 754) ✓ ISO / ASME Validated

Reflux Partial Condenser Sizer (Dephlegmator)

Heat Exchangers

📊 Solver Telemetry ● ACTIVE

👁️ Views 25

⚡ Solves 20

💾 Downloads 373 📦 Fortran Code 4.1 KB

📅 Released Jun 2026

⏱️ Latency < 1 ms

⚡ Counter-Current Vapor Ascent & Falling Liquid Reflux

Real-time visual simulation: Upward rising binary vapor, falling condensate reflux, and overhead purified vapor

📝 Configuration & Presets

🌾 Bioethanol Column Top 🧪 Methanol Stripper Reflux 🛢️ Aromatics Benzene-Toluene 💊 Pharma Acetone Recovery

🧪 Binary Vapor Mixture from Column

Vapor Mixture System:

Vapor Feed Flow ṁ_vap [kg/h]:

Vapor Inlet Temp T_v,in [°C]:

Inlet Light Mole Fraction y_in [%]:

Condensation Reflux Ratio R:

📐 Vertical Tube Bundle Geometry

Number of Vertical Tubes:

Tube Inner Diameter D_i [mm]:

Tube Active Length L [m]:

Cooling Water Inlet T_cool [°C]:

Hewitt & Wallis Flooding Model:
• Flooding Velocity Limit: V_flood = 0.85 · √[g·D_i·(ρ_L−ρ_v)/ρ_v] · [1 + (ρ_v/ρ_L)^1/4·(ṁ_L/ṁ_v)^1/2]^-2
• Flooding Margin: (V_actual / V_flood) · 100% < 80% (Safe operation)
• Silver-Bell-Ghaly Condensation: 1/U = 1/h_cond + Z/h_gas + t_w/k_w + 1/h_cool.

📊 Performance Results

📊 Output Summary
💾 Fortran Source

Enriched Overhead Vapor Purity

77.8 mol% (Enriched)

Inlet: 70.0% | Duty: 257.7 kW

SAFE COUNTER-CURRENT FLOW

Flooding Limit Approach 35.0% V = 2.19 m/s / Vfl = 6.25 m/s

Reflux Condensate Return 2275 kg/h 65% reflux split

Overhead Distillate Vapor Flow 1225 kg/h Purified top product

Overall U-Value (Silver-Bell) 405 W/(m²·K) 140 vertical tubes

📈 Flooding % vs Number of Vertical Tubes Nt

📊 Overhead Purity ytop (mol%) vs Reflux Fraction

=================================================================
 THERMOFLUIDCALC — REFLUX CONDENSER (DEPHLEGMATOR) REPORT
=================================================================
Case Title                 : Aromatics Benzene-Toluene Column Dephlegmator
Binary Mixture             : Benzene-Toluene (Petroleum Aromatics Fractionator)
Vapor Feed Conditions      : mvap = 3500.0 kg/h, Tv = 92.0 C, yin = 70.0 mol%
Condenser Geometry         : Nt = 140 tubes, Di = 38.0 mm, L = 4.00 m
-----------------------------------------------------------------
VAPOR VELOCITY / FLOOD LIM : 2.19 m/s / 6.25 m/s
FLOODING APPROACH MARGIN   : 35.0% (SAFE COUNTER-CURRENT FLOW)
OVERHEAD VAPOR PURITY      : 77.80 mol% (Enriched from 70.0%)
Reflux Condensate Flow     : 2275.0 kg/h
Overhead Distillate Flow   : 1225.0 kg/h
THERMAL CONDENSER DUTY (Q) : 257.74 kW
Overall Heat Transfer (U)  : 405.0 W/(m2.K)
=================================================================

📘 Calculation Methodology & Dephlegmator Standards

Internal Distillation Action

In a reflux partial condenser (dephlegmator), the counter-current contact between upward rising vapor and descending condensate film provides additional theoretical distillation stages, significantly enriching the overhead vapor.

Hewitt & Wallis Flooding Limit

High upward vapor velocities can bridge the tube diameter and prevent liquid reflux from descending, causing column liquid entrainment and pressure surge.

Key Engineering Assumptions

Silver-Bell-Ghaly multicomponent partial condensation resistance model.
Rayleigh fractionation equilibrium enrichment.
Widely used in bioethanol distillation, solvent recovery, and petrochemical fractionators.

ThermoFluidCalc Engineering Report