ERT 318/4
UNIT OPERATIONS
SEMESTER 1 (2013/2014)
DISTILLATION OPERATION
School of Bioprocess Engineering
University Malaysia Perlis
1.0
2.0
OBJECTIVE
Experiment 1
1. To perform batch distillation on a binary mixture using a continuous distillation column
with constant reflux ratio.
2. To investigate the composition of top product during the distillation period.
Experiment 2
1. To perform batch distillation on a binary mixture using a continuous distillation column
and regulate the reflux ratio.
2. To study the effect of regulating reflux ration on the purity of the top product.
2.0
CORRESPONDING COURSE OUTCOME
Ability to describe, analyze and evaluate the gas-liquid and vapor-liquid separation
equipments
3.0
MATERIALS AND EQUIPMENTS
3.1 Apparatus
Figure 1: Distillation Column Unit
Legend
A. Top product condenser
B. Solvent tank
C. Feed pump
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D. Packed column, sieve plate column
E. Evaporator tank
F. Bottom product heat exchanger
G. Bottom product
H. Product tank
I. Preheated-product tank
J. Control panel
K. Top product tank
L. Reflux tank
3.2 Description
Distillation process is widely applied in the engineering industry for mass transfer and
separation operations. This is done by vaporization of a liquid mixture of miscible and volatile
substances into individual components.
A sieve plate distillation column comprises of 8 plates. One of the plates is clearly shown
during the distillation process via the borosilicate glass section. Sieve plates are designed to
illustrate the actual plant column construction with underflow weir and downcomer.
A coil type overhead condenser made of stainless steel is connected to the top of the
column to condense the product vapors to be collected at the reflux divider. Reflux control is
made possible from 0 - 100% via electronic control valves. A glass product collector sits below
the reflux divider with a sample port fitted for collection of final product to be analyzed. A
stainless steel fully insulated reboiler is connected at the base of the column to evaporate
process substances. A jet vacuum pump fitted at the top product line allows vacuumed
distillation operation.
3.3 Technical Specifications
Process Unit
•
60mm diameter sieve plate column made of stainless steel and borosilicate glass containing 8
sieve plates with downcomers and underflow weirs ; every plate incorporates a temperature
sensor positioned to accurately measure the liquid temperature.
•
10L electrical heated reboiler made of stainless steel with sight level glass and full insulation;
level switch and digital temperature controller included for protection with low level warning
alarm; comes with internal overflow during continuous operation.
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•
Overhead coil type condenser made of borosilicate glass to allow vapor and condensate to be
viewed, comes with cooling water flow meter.
•
Condensate collector made of borosilicate glass with double overflow weirs and exit pipes to
allow separation of immiscible liquids.
•
Reflux return valve, electrical operated to allow reflux setting of 0 - 100% via signal.
•
Differential manometer connected to measure column top and bottom pressure drop.
•
Jet pump for vacuum down to 200 mbar(abs) ; comes with pressure gauge.
•
2 x 10L cylindrical feed tanks made of stainless steel.
•
10L cylindrical glass product tank with drain and venting port.
•
Chemical resistant feed pump - 18L/hr.
•
Dosing feed vessel connected to the column for continuous addition of third liquid component
which together with the condensate phase separator vessel, allows study of azeotropic
distillation.
•
Bottom product heat exchanger which may be water cooled or used as feed pre-heater.
•
Maximum process temperature 1300C.
•
Heater capacity 2000 W.
•
Heater power controller with transducer.
•
Water flow meter 0 - 400 Liters/hour.
•
15 point thermocouple measurement with digital display.
•
Column pressure gauge.
•
Safety relieve valve x 2 units.
4.0
SAFETY & PRECAUTION
1. Read the safety instructions throughly before conducting the experiment.
2. Wear protective gloves, glasses, laboratory protective clothing, long pants and closed
toe shoes when conducting the experiment.
3. Dispose of all unused chemicals in an appropriate manner after the experiment. Under
no circumstances should the chemicals be allowed to flow into the main drains.
4. Should any of the chemicals come into contact with the body, rinse off immediately
with cold water and inform the lab attendant. Seek medical treatment if symptoms
persist.
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5. Report any breakages or consumables which need replenishing.
6. Wash your hands thoroughly with soap after the experiment.
7. Be alert and careful at all times when conducting the experiment.
8. Do not touch the heat plate or air duct when conducting the experiment.
9. Do not touch the fan when conducting the experiment.
10. Ensure the heat plate is cooled down before remove away from the air duct.
11. Be careful when using the handheld digital anemometer. Keep it away once the air
velocity is measured.
12. Be careful when connecting the heat socket to the power source.
13. Be careful when dealing with chemicals.
14. Do not attempt to change the setting of the digital power meter.
Safety
Footwear
Safety
Goggle
Lab Coat
5.0
EXPERIMENTAL PROCEDURES
5.1
CHEMICAL PREPARATION
Chemical
Gloves
Chemical
Respirator
Distilled water/ethanol mixture
To prepare a mixture of composition X% of ethanol, observe the following steps.
5.1.1
Fill a 1 L measuring cylinder with 10X mL of ethanol.
5.1.2
Pour ethanol into a 1 L beaker.
5.1.3
Fill the beaker up to 1 L with distilled water.
5.1.4
Stir using a glass rod.
5.1.5
The product is now a 1 L batch of binary mixture with X% v/v of component A.
For example, to create a 35% v/v mixture of ethanol, pour 350 mL of ethanol into a
beaker, and fill the beaker up to 1 L with either distilled water.
NOTE
1. Ethanol are volatile and will evaporate quickly. Avoid exposing this chemical to the
atmosphere for extended periods of time.
2. Dispose of all unused chemicals in an appropriate manner after the experiment. Under
no circumstances should the chemicals be allowed to flow into the main drains.
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5.2
REFRACTIVE INDEX GRAPH
To obtain the refractive index data for ethanol-water solution
5.2.1
Prepare 100ml distilled water.
5.2.2
Obtain 10ml of ethanol.
5.2.3
Measure the refractive index for both distilled water and ethanol by digital handheld
refractor meter.
5.2.4
Record the refractive index for each.
5.2.5
Dilute 10ml of ethanol with 100ml of distilled water in a beaker. Then measure the
refractive index by refractor meter.
5.2.6
Add another 10 ml of ethanol into beaker and measure the refractive index. Repeat
this procedure until 100ml of ethanol is added.
5.2.7
Prepare 100ml of ethanol and 10ml of distilled water in a beaker. Measure the
refractive index by refractor meter.
5.2.8
Add another 10ml of distilled water into the same beaker. Repeat the procedure
until 90ml of distilled water is added.
5.3
EXPERIMENT 1
5.3.1 Experiment Pre-Procedure
1. Place the LS-32 203-continuous distillation column on a floor level.
2. Plug the 3 pin plug to the 240VAC main power supply. Turn ON the power supply.
3. Switch ON the power supply unit in front of the control panel.
4. Connect cooling water inlet and outlet to the main water hose.
5. Shut down all valves
6. Fill the evaporator tank with solution (ethanol-distilled water)
7. Open vacuum cooling inlet ( V10) and vacuum valve (V9) to vacuum top product
condenser and reflux tank. Leave it for 10 minutes.
8. Close Vacuum valve (V9)
9. Open cooling water inlet (V11)
10. Close vacuum cooling inlet (V10).
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5.3.2 Procedure
1. Prepare a 10 L batch of binary mixture (refer to CHEMICAL PREPARATION) of known
composition.
2. Collect a 10 mL sample using a syringe and test the refractive index.
3. Record the refractive index shown.
4. Pour the mixture into the evaporator tank.
5. Setup the unit according to experiment pre-procedure.
6. Note: Do not open vacuum valve (V10) and (V9) for the vacuum pump during the
experiment. Operation of the vacuum pump after the mixture is partially
vaporized will cause the fluids to gush upwards, damaging the column.
7. Set the temperature of the evaporator tank, T13 to 90°C using the temperature
controller.
8. Using the potentiometer, set the reflux to 100%.
9. Once the top product appears in the phase break vessel, run the column at total reflux
for another 10 minutes.
10. Record down all the temperatures.
11. Take a sample from evaporator tank and phase break vessel and measure the
refractive index.
12. Using the potentiometer, set the reflux ratio to the between ( 50% - 80%.)
13. At intervals of 10 minutes, record down all temperatures and draw a sample from the
top product tank (5) and evaporator tank(2). Measure and note down the refractive
index of each sample. To quickly cool down the evaporator sample, place the test tube
in a beaker filled with ice water.
14. Take 3 readings. Then, empty the top product vessel and measure its volume.
15. Tabulate the data obtained.
16. After the experiment, drain off the contents in the evaporator tank , phase break vessel
and top product tank . All alcohol samples can be re-used after the experiment, as long
as they are uncontaminated.
17. Switch off the main power switch and power supply. Turn off the water supply and
disconnect the hoses.
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5.4
EXPERIMENT 2
5.4.1 Experiment Pre-Procedure
1.
Place the LS-32 203-continuous distillation column on a floor level.
2.
Plug the 3 pin plug to the 240VAC main power supply. Turn ON the power supply.
3.
Switch ON the power supply unit in front of the control panel.
4.
Connect cooling water inlet and outlet to the main water hose.
5.
Shut down all valves
6.
Fill the evaporator tank with solution (ethanol-distilled water)
7.
Open vacuum cooling inlet ( V10) and vacuum valve (V9) to vacuum top product
condenser and reflux tank. Leave it for 10 minutes.
8.
Close Vacuum valve (V9)
9.
Open cooling water inlet (V11)
10.
Close vacuum cooling inlet (V10).
5.4.2 Procedure
1.
Prepare a 10 L batch of binary mixture (refer to CHEMICAL PREPARATION) of known
composition.
2.
Collect a 10 mL sample using a syringe and test the refractive index.
3.
Pour the mixture into the evaporator tank.
4.
Setup the unit according to pre-procedure instructions.
5.
Note: Do not open vacuum valve (V10) and (V9) for the vacuum pump during the
experiment. Operation of the vacuum pump after the mixture is partially
vaporized will cause the fluids to gush upwards, damaging the column.
6.
Set the temperature of the evaporator tank, T13 to 90°C using the temperature
controller.
7.
Using the potentiometer, set the reflux to 100%.
8.
Once the top product appears in the phase break vessel, run the column at total reflux
for another 10 minutes.
9.
Record down all the temperatures.
10.
Take a sample from evaporator tank and phase break vessel and measure the
refractive index.
11.
Using the potentiometer, set the reflux ratio to the 50%.
12.
At intervals of 10 minutes, record down all temperatures and draw a sample from the
top product tank and evaporator tank . Measure and note down the refractive index of
each sample. To quickly cool down the evaporator sample, place the test tube in a
beaker filled with ice water.
Increase the reflux by 20% after each interval until 90% reflux.
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13.
After 3 readings have been obtained, empty the top product vessel and measure its
volume.
14.
Tabulate the data obtained.
15.
After the experiment, drain off the contents in the evaporator tank, phase break vessel
and top product tank. All alcohol samples can be re-used after the experiment, as long
as they are uncontaminated.
16.
Switch off the main power switch and power supply. Turn off the water supply and
disconnect the hoses.
6.0
PROCESS FLOW DIAGRAM
6.1 Draw a Process Flow Diagram (PFD).
7.0
RESULT AND CALCULATION
7.1
Record all data obtained from the experiment and calculate in an appropriate
table(s).
7.2
Plot a graph of Refractive Index versus Mass Fraction of ethanol.
7.3
Calculate the q-line and operating line equations.
7.4
Construct a graphical method of McCabe-Thiele Method and determine the
theoretical stage required for this separation.
Useful Data
Heat capacity of ethanol, Cp = 158.8 kJ/kmoloC
Heat capacity of water, Cp = 75.4 kJ/kmoloC
8.0
9.0
DISCUSSION
8.1
Discuss the finding of the graphs and results.
8.2
Discuss the effect of regulating reflux ratio on the purity of the top product.
QUESTION
9.1
How does different reflux ratio affect the column performance?
9.2
What is the definition of total reflux?
9.3
What is the definition of minimum reflux?
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10.0
CONCLUSION
10.1
Based on the experimental procedure done and the results taken draw some
conclusions to this experiment.
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