binary distillation

ChE 382 Group 5 1

Binary DistillationGroup 5

Alex GuerreroAndrew DuffyBernard Hsu

Daniyal QamarJeff Tyska

Ryan KosakTomi Damo

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ChE 382 Group 5 2

Introduction Binary distillation involves only 2

components It works by using the differences in

boiling points for separation› Methanol BP: 65°C› Water BP: 100°C

This column uses multiple trays for separation

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ChE 382 Group 5 3

Introduction The column runs under total reflux

› Therefore no methanol vapor leaves

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ChE 382 Group 5 4

Purpose The purpose of this experiment is to:

› Separate a binary mixture of methanol and water

› Learn how to use a refractometer› Create a calibration curve › Use live data from the refractometer to

determine the degree of separation throughout the column

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ChE 382 Group 5 5

Theory Works by the difference in component

volatilities Lighter compounds (lower boiling point)

will have a higher concentration in the vapor phase

Like wise the heavier compounds will be found in the liquid phase

Relative volatility is the ratio of the volatilities of the lighter component over the volatility of the heavier component

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ChE 382 Group 5 6

Theory Heat is supplied in the reboiler The condenser at the top uses cold

water and runs under total reflux› Total reflux = no operating lines on

McCabe-Thiele diagram

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ChE 382 Group 5 7

Theory Murphee tray efficiency

Where:› η = plate efficiency› yn = mole fraction of component in vapor phase at tray n

(dimensionless)› yn+1 = mole fraction of component in vapor phase at tray

n+1 (dimensionless)yn

* = the composition in equilibrium with Xn (dimensionless)

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ChE 382 Group 5 8

Apparatus: Column No. Component

1 Condenser2 Water Supply3 Liquid Rotameter4 Stages (6)5 Filling Tank6 Ladder7 Distillation Column Drain8 Drain/Fill Valve9 Pressure Gauge

10 Control Valve (flow rate)11 Pressure Gauge Valve

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ChE 382 Group 5 9

Apparatus: Column DetailsNo. Component

12 Heater13 Thermometer14 Digital Thermometer15 Round Bottom Flask16 Reboiler17 Vapor Release Valve18 Gas Tube19 Liquid Release Valve20 Liquid Tube21 Funnel22 Filling Tank Valve

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ChE 382 Group 5 10

Apparatus: RefractometerNo. Component

23 Refractometer24 Eyepiece25 Thermometer26 Fine Tuning Knob27 Focus Knob28 Light Source29 Scale Illumination30 Illumination Prism31 Cold Water Tubing

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ChE 382 Group 5 11

Apparatus: Ice BathNo. Component

32 Ice Bath33 Liquid Controller34 Temperature Controller35 Switch36 Digital Thermometer37 Heating Coil

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ChE 382 Group 5 12

Materials

No.Material/Supply Description/Use

1 Tap Water Used to make 5 wt% MeOH solution and supplied to condenser2 Methanol 99.8% Anhydrous. Used to make 5 wt% MeOH working solution

3 GlovesProtect hands from toxic MeOH and prevent MeOH from drying hands

4 Goggles Eye protection

5Graduated Cylinders Measure MeOH amount to make 5 wt% solution

6 Ladder To elevate operator so that he or she can add MeOH to filling tank

7Small Test Tubes

To collect samples of liquid and vapor at each stage of distillation column

8 Distilled WaterTo clean the refractometer between readings, to make different MeOH wt% solutions when doing calibration curve

9 IceTo create an ice bath for refractometer to maintain 34ºF temperature

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ChE 382 Group 5 13

Procedure Creating the Calibration Curve:1. Plug in the Refractometer (23) and ice bath (32).2. Obtain ice from the Chemical Engineering office, fill the ice bath

about half way with ice, and add water.3. Adjust the heating to keep the system at 32°F.4. Create samples of methanol and water by mixing solutions of 0-

100% (use increments of 10) methanol by volume in small test tubes (cover with para-film until testing).

5. Place sample under the illumination prism (30), look through the eye piece (24), press the illumination button near the back of the machine then adjust the X to line up with the vertical line using the fine tuning knob (26) and record the value of refraction.

6. Clean off sample with the provided Kimwipes and repeat for all the samples to create a calibration curve of refraction versus volume percent of methanol.

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ChE 382 Group 5 14

Procedure Using the Batch Distillation Column:1. Make sure the drain valve for the filling tank (5) is set to the “Fill” setting and the tank is

closed.2. Measure out 1.6 L of methanol and pour it through the funnel (21) into the filling tank (5)

then add 32 L of water to the tank using the filling tank hose just above the funnel to create 0.05% by volume mixture.

3. Once the tank is full turn the Fill/Drain valve to “Drain” then open the filling tank valve (22) to allow the mixture to fill the round bottom flask (15) of the distillation column.

4. When the filling tank (5) is empty close the filling valve (22) and call the TA or instructor to turn on the reboiler (16).

5. Record the temperatures of thermocouples using the digital thermometer (14) every 20 minutes until steady state is met.

6. Obtain samples of vapor and liquid from each stage using the vapor and liquid release valves (17 and 19).

7. Use the refractometer (23) to obtain the refraction index of each sample (Use the same procedure as the calibration curve).

8. Once all the samples are collected and measured turn off the column and allow it to drain.

9. Unplug and clean the refractometer (23) and ice bath (32).10. Dispose of samples accordingly.

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ChE 382 Group 5 15

Safety The reboiler gets hot so avoid contact The samples taken from the column are

very hot Be careful when using the ladder Avoid spilling any methanol Avoid skin contact with methanol Ensure the area around the column is

cleaned of any spilled water Make sure no methanol vapor leaves the top

of the column4/14/2011

ChE 382 Group 5 16

References “Binary Distillation.”University of Illinois at Chicago - UIC. Web. 13

Sept. 2010. <http://www.uic.edu/depts/chme/UnitOps/entry.html>. Gilbert, John C., and Stephen F. Martin. Experimental organic

chemistry: a miniscale & microscale approach. 4th. BrooksCole Pub Co, 2006. 137. Print.

http://www.separationprocesses.com/Distillation/DT_Chp05.htm McCabe, Warren L., Julian C. Smith, and Peter Harriott. Unit

Operations of Chemical Engineering. New York: McGraw-Hill, 1993. (pp: 578-579) Print.

Stichlmair, Johann. 2000. “Distillation and Rectification.” Encyclopedia of Industrial Chemistry. 7th. 40. New York, NY: Wiley-VCH Verlag GmbH & Co., 2010. (pp: 1-97) Print.

Wankat, Phillip C. Separation Process Engineering. (2nd Edition). Boston, MA: Pearson

  Education, Inc., 2007. (pp: 187 – 284) Print

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