Batch Distillation Simulator

Rigorous multicomponent ideal mixture simulation using Antoine's equation. Supports Simple Batch (N=0) and Staged Constant Reflux distillation with multi-cut receiver scheduling.

US CUSTOMARY METRIC / SI

1. Project Data

Project Name

Column Tag

Engineer

2. Mixture Components

Equation form: $\log_{10}(P^{sat}) = A - \frac{B}{T + C}$ (Internal calculation uses mmHg and °C regardless of input units).

#	Component Name	Feed (kmol)	Actions
Total Initial Pot Charge (kmol):		0.00

3. Column Configuration

Operating Pressure (bar)

Theoretical Stages ($N$) N=0 for Simple Batch (Rayleigh).

Boilup Rate, $V$ (kmol/hr)

Stage Holdup (kmol/stage)

4. Operating Policy

Operating Mode

Constant Reflux Ratio ($R$)

Reflux Ratio ($R = L/D$)

Stop Condition

Max Time (hr)

Stop when Pot Moles (kmol) $\le$

Cut Schedule optional

Click to define receiver cuts

5. Equipment Sizing Estimates

Preliminary estimates at initial (peak) vapour load. Ideal VLE and ideal liquid mixing assumed. Watson correlation for ΔH_vap temperature correction. Not for detailed mechanical design.

Column Sizing

Sieve / Valve Tray Column — Souders-Brown, C_sb = 0.05 m/s at 600 mm tray spacing, 75% flood

Column Diameter

Design Vapour Velocity

m/s

Flood Velocity

m/s

Packed Column — 1" IMTP (Koch-Glitsch) — GPDC-based flooding, C_pk = 0.065 m/s, 70% flood; HETP = 0.40 m/stage

Column Diameter

Design Vapour Velocity

m/s

Packed Height

HETP

0.40

m/stage

1" IMTP: a_p = 207 m²/m³ | F_p = 41 ft²/ft³ | ε = 0.978 | Flood velocity: - m/s

Thermal Duties

Condenser — Peak

kcal/h

Reboiler — Peak

kcal/h

Condenser — Total

kcal

Reboiler — Total

kcal

Still Pot (Reboiler Vessel)

Liquid Volume

m³

Vessel Volume

m³

Shell Diameter

L/D = 1.5, fill fraction = 60%. Tangent-to-tangent height: - m

Simulation Summary

Total Time (hr) -

Initial Charge (kmol) -

Final Pot Moles (kmol) -

Total Distillate (kmol) -

Avg Distillate Purity, $x_{D,0}$ -

Dynamic Concentration Profiles

Engineering Reference & Technical Basis

1. Thermodynamics & Vapor-Liquid Equilibrium (VLE)

The application models ideal multicomponent mixtures. Vapor pressures are calculated using the Antoine Equation:

\[\log_{10}\!\left(P_i^{\text{sat}}\right) = A_i - \frac{B_i}{T{^\circ\!C}+C_i}\]

where $P_i^{\text{sat}}$ is in mmHg and $T$ in °C. VLE is determined by Raoult's Law:

\[y_i = x_i \frac{P_i^{\text{sat}}}{P}\]

Stage temperatures are found by Newton-Raphson on the bubble point condition $\sum_i y_i = 1$.

2. Dynamic Mass Balances (ODE System)

The process is a system of ODEs solved by an adaptive-step explicit Euler method.

Simple Batch (Rayleigh Distillation, N = 0)

\[\frac{dx_{W,i}}{dt} = \frac{V}{W}\!\left(y_{W,i} - x_{W,i}\right)\]

Staged Distillation (N > 0) — Constant Molar Overflow

Distillate rate $D = V/(R+1)$, reflux rate $L = R \cdot D$.

Condenser:

\[H_D\frac{dx_{D,i}}{dt} = V\,y_{N,i} - (L+D)\,x_{D,i}\]

Tray $j$:

\[H_T\frac{dx_{j,i}}{dt} = V(y_{j-1,i}-y_{j,i}) + L(x_{j+1,i}-x_{j,i})\]

Still Pot:

\[W\frac{dx_{W,i}}{dt} = L\,x_{1,i} - V\,y_{W,i} + D\,x_{W,i}\]

Integration step: $\Delta t = 0.1 \cdot H_T/V$ (10× stability margin).

3. Column Profile Pre-Initialisation

Before integration, tray compositions are pre-initialised to the steady-state enrichment profile using the rectifying section operating line, iterated 8 times to convergence:

\[x_{j+1,i} = \frac{V\,y_{j,i} - D\,x_{D,i}}{L}\]

This ensures physically distinct condenser and reboiler duties from $t = 0$.

4. Energy Balance & Thermal Duties

Condenser Duty (kW):

\[Q_{\text{cond}} = \frac{V}{3600}\sum_i y_{\text{top},i}\,\Delta H_{\text{vap},i}(T_D)\]

Reboiler Duty (kW):

\[Q_{\text{reb}} = \frac{V}{3600}\sum_i y_{W,i}\,\Delta H_{\text{vap},i}(T_W)\]

Watson Correlation for temperature-dependent $\Delta H_{\text{vap}}$:

\[\Delta H_{\text{vap}}(T) = \Delta H_{\text{vap,bp}}\!\left(\frac{T_c-T}{T_c-T_{\text{bp}}}\right)^{\!0.38}\]

5. Equipment Sizing Correlations

All sizing is based on peak (initial) vapour load. Vapour density from ideal gas law; liquid density from ideal mixing.

Tray Column — Souders-Brown (Fair, 1961)

\[u_{\text{flood}} = C_{sb}\!\sqrt{\tfrac{\rho_L-\rho_V}{\rho_V}},\quad C_{sb}=0.05\;\text{m/s}\]

600 mm tray spacing; design at 75% flood.

Packed Column — 1" IMTP, Koch-Glitsch GPDC (Strigle, 1994)

\[u_{\text{flood}} = C_{pk}\!\sqrt{\tfrac{\rho_L-\rho_V}{\rho_V}},\quad C_{pk}=0.065\;\text{m/s}\]

a_p = 207 m²/m³ F_p = 41 ft²/ft³ ε = 0.978 HETP = 0.40 m/stage

Design at 70% flood.

Still Pot Vessel

Liquid volume $V_L = W_0\bar{M}_L/\rho_L$; vessel volume at 60% fill; L/D = 1.5:

\[D_{\text{pot}} = \!\left(\frac{4\,V_{\text{vessel}}}{\pi\cdot 1.5}\right)^{\!1/3}\]

6. Physical Property Databank

Built-in databank covers 30 common solvents with the following properties:

Property	Symbol	Units	Source
Antoine constants	A, B, C	log₁₀(P/mmHg), T/°C	Poling et al. (2001); Perry's 8th ed.
Molecular weight	M_W	kg/kmol	IUPAC atomic weights
Liquid density	ρ_L	kg/m³ at 20°C	Perry's 8th ed.; NIST WebBook
Heat of vaporisation	ΔH_vap	kJ/kmol at T_bp	Poling et al. (2001); NIST WebBook
Critical temperature	T_c	K	Poling et al. (2001)
Normal boiling point	T_bp	°C	Perry's 8th ed.

References

Poling, B.E., Prausnitz, J.M., O'Connell, J.P. The Properties of Gases and Liquids, 5th ed. McGraw-Hill, 2001.
Perry, R.H., Green, D.W. Perry's Chemical Engineers' Handbook, 8th ed. McGraw-Hill, 2008.
Strigle, R.F. Packed Tower Design and Applications, 2nd ed. Gulf Publishing, 1994.
Diwekar, U.M. Batch Distillation: Simulation, Optimal Design and Control, 2nd ed. CRC Press, 2012.
Watson, K.M. Prediction of critical temperatures and heats of vaporisation. Ind. Eng. Chem., 23(4), 360–364, 1931.
Fair, J.R. How to predict sieve tray entrainment and flooding. Petro/Chem Engineer, 33(10), 45–52, 1961.
Koch-Glitsch. IMTP® Random Packing — Technical Data Sheet. Koch-Glitsch LP, 2012.
NIST Chemistry WebBook. National Institute of Standards and Technology. webbook.nist.gov