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4/14/2011 1 ChE 382 Group 5

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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

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The column runs under total reflux Therefore no methanol vapor leaves 4/14/2011 ChE 382 Group 5 3

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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

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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

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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

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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

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No.Component 1Condenser 2Water Supply 3Liquid Rotameter 4Stages (6) 5Filling Tank 6Ladder 7Distillation Column Drain 8Drain/Fill Valve 9Pressure Gauge 10Control Valve (flow rate) 11Pressure Gauge Valve 4/14/2011ChE 382 Group 5 8

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No.Component 12Heater 13Thermometer 14Digital Thermometer 15Round Bottom Flask 16Reboiler 17Vapor Release Valve 18Gas Tube 19Liquid Release Valve 20Liquid Tube 21Funnel 22Filling Tank Valve 4/14/2011ChE 382 Group 5 9

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No.Component 23Refractometer 24Eyepiece 25Thermometer 26Fine Tuning Knob 27Focus Knob 28Light Source 29Scale Illumination 30Illumination Prism 31Cold Water Tubing 4/14/2011ChE 382 Group 5 10

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No.Component 32Ice Bath 33Liquid Controller 34Temperature Controller 35Switch 36Digital Thermometer 37Heating Coil 4/14/2011ChE 382 Group 5 11

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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

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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

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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

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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

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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