Aim of the Experiment
To study the operation of a distillation column, to determine tray efficiency using the McCabe-Thiele graphical method, and to study the effect of reflux ratio on product composition and column performance.
Apparatus Required
- Distillation column (sieve tray or bubble cap column)
- Reboiler with heater and temperature controller
- Condenser with cooling water supply
- Reflux divider / splitter
- Refractometer or hydrometer (for composition measurement)
- Thermometers / temperature sensors at each tray
- Sampling ports at feed, distillate, and bottoms
Theory
Distillation is a separation process based on differences in volatility (boiling points) of components in a liquid mixture. In a distillation column, vapour rises up the column and liquid flows downward. At each tray, vapour and liquid come into contact and approach equilibrium, the more volatile component (MVC) concentrates in the vapour phase.
Reflux Ratio: R = L/D, where L is liquid returned to the column (reflux) and D is distillate product flow.
Operating Line (Rectifying section): y = [R/(R+1)] × x + x_D/(R+1)
McCabe-Thiele Method: Graphical construction on a vapour-liquid equilibrium (VLE) diagram. Theoretical trays are stepped off between the equilibrium curve and operating lines. Tray efficiency = (actual trays) / (theoretical trays needed).
Murphree Tray Efficiency: E_mv = (y_n − y_{n+1}) / (y*_n − y_{n+1})
Procedure
- Charge the reboiler with a known feed mixture (e.g., ethanol-water, 30–40% ethanol by volume).
- Switch on the heater. Set the reflux ratio to a known value (e.g., R = 3).
- Allow the column to reach steady state (approximately 45–60 minutes). Monitor temperatures at each tray, they should stabilise.
- Collect samples from the distillate and bottoms outlets.
- Measure compositions (mole fractions) of distillate (x_D) and bottoms (x_B) using a refractometer or calibrated hydrometer.
- Draw the McCabe-Thiele diagram: plot VLE curve, rectifying operating line, stripping operating line, and step off theoretical trays.
- Calculate overall column efficiency: E_o = N_theoretical / N_actual.
- Repeat for a different reflux ratio (e.g., R = 5) and compare distillate composition and efficiency.
Observation Table
| Parameter | Run 1 (R=3) | Run 2 (R=5) |
|---|---|---|
| Feed composition x_F (mole fraction) | ||
| Distillate composition x_D | ||
| Bottoms composition x_B | ||
| Reboiler temperature (°C) | ||
| Distillate temperature (°C) | ||
| Theoretical trays (McCabe-Thiele) | ||
| Actual trays | ||
| Overall efficiency E_o (%) |
Result
Overall tray efficiency at R = 3: E_o = _______%. At R = 5: E_o = _______%. A higher reflux ratio gives purer distillate but reduces column capacity and increases energy consumption. The McCabe-Thiele construction confirms the number of theoretical stages required.
Internal Links
Related: Process Engineering Lab Equipment | Process Engineering Lab Setup Guide | Dissolution Apparatus Experiment | Instruments in Chemistry Lab
Get Process Engineering Lab Equipment
Scientico India manufactures ISO 9001:2015 and CE-certified process and chemical engineering lab apparatus including distillation columns, heat exchangers, and fluid handling systems.
Scientico India manufactures this and the full range of Process Engineering equipment, CE-certified and supplied to engineering colleges worldwide.
Explore Process Engineering Equipment → or request a quoteDefine the distillation teaching outcome before choosing the column
A column intended for reflux-ratio or stage-efficiency work needs a clear feed system, reboiler, condenser, reflux control and temperature or sampling locations. The proposed fluid system, operating pressure and laboratory utilities must be suitable for the intended teaching method and local safety procedure.
What to confirm before requesting a quotation
- State batch or continuous operation and the proposed mixture.
- Confirm column internals, stage count and sampling or temperature points.
- Define reflux measurement/control and energy-input measurement.
- List cooling water, ventilation, drainage and electrical requirements.
For an international order, also state the quantity, destination, electrical supply, documentation, installation or training needs and requested delivery basis. Treat catalogue information as a starting point; the current model page, datasheet and written quotation must confirm the exact configuration.
Distillation trainer: process flow, measurements and utilities
One honest ask
We don't gate anything on this site. You just read the whole thing free. If it was useful, leave your email and two things happen: we send you this page as a plain-text block you can paste into a tender file or an internal email, and we notify you the next time we publish a buyer tool like this one. Nothing else. No drip sequence, no sales calls booked without asking.