4/14/2011 1 ChE 382 Group 5. Binary distillation involves only 2 components It works by using the...
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4/14/2011 1 ChE 382 Group 5. Binary distillation involves only 2 components It works by using the differences in boiling points for separation › Methanol
Binary distillation involves only 2 components It works by
using the differences in boiling points for separation Methanol BP:
65 C Water BP: 100C This column uses multiple trays for separation
4/14/2011 2 ChE 382 Group 5
Slide 3
The column runs under total reflux Therefore no methanol vapor
leaves 4/14/2011 ChE 382 Group 5 3
Slide 4
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 4/14/2011 4 ChE 382
Group 5
Slide 5
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 4/14/2011 5 ChE 382 Group 5
Slide 6
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 4/14/2011 ChE 382 Group 5 6
Slide 7
Murphee tray efficiency Where: = plate efficiency y n = mole
fraction of component in vapor phase at tray n (dimensionless) y
n+1 = mole fraction of component in vapor phase at tray n+1
(dimensionless) y n * = the composition in equilibrium with X n
(dimensionless) 4/14/2011 ChE 382 Group 5 7
No.Material/SupplyDescription/Use 1Tap WaterUsed to make 5 wt%
MeOH solution and supplied to condenser 2Methanol99.8% Anhydrous.
Used to make 5 wt% MeOH working solution 3Gloves Protect hands from
toxic MeOH and prevent MeOH from drying hands 4GogglesEye
protection 5 Graduated CylindersMeasure MeOH amount to make 5 wt%
solution 6LadderTo 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 8Distilled Water To
clean the refractometer between readings, to make different MeOH
wt% solutions when doing calibration curve 9IceTo create an ice
bath for refractometer to maintain 34F temperature 4/14/2011 12 ChE
382 Group 5
Slide 13
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 32F. 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.
4/14/2011 13 ChE 382 Group 5
Slide 14
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. 4/14/2011 ChE 382 Group 5
14
Slide 15
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 column 4/14/2011 15 ChE 382
Group 5
Slide 16
Binary Distillation.University of Illinois at Chicago - UIC.
Web. 13 Sept. 2010.. 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
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. (2 nd Edition).
Boston, MA: Pearson Education, Inc., 2007. (pp: 187 284) Print
4/14/2011 16 ChE 382 Group 5