Question

Distillation- McCabe-Thiele

A saturated vapor feed (pure vapor at the dew point) containing 52 mol% toluene and 48 mol% n-octane is to be fractionated at 101.3 kPa abs. to give a distillate containing 95 mol% toluene at 10 kmol/hr and a bottoms containing 5 mol% toluene. Use McCabe-Thiele graphical method to answer the following questions:

a) Draw a vapor-liquid equilibrium diagram. Do this in excel and use gridlines to produce a nice figure that you can use for the rest of the steps. (Note: you should already have this from HW#04.)

b) Calculate the flowrates of the feed and bottoms.

c) Determine the minimum reflux ratio (Rmin).

d) Using R = 1.5 Rmin, determine the theoretical number of trays required. (Remember the reboiler) e) Using R = 1.5 Rmin, determine the feed tray number. (Remember the rule for the feed location)

Answer #1

Rectification. McCabe-Thiele Method. A mixture of
benzene-toluene is to be distilled in a fractionating tower at
101.3 kPa. The column is fed 120 kg mol /h of a saturated liquid at
the boiling point with 60 mol % benzene and 40 mol % toluene. The
content of the distillate is 92 mol % benzene, and of the bottoms 5
mol % benzene. The reflux ratio is 3:1.
(a) Calculate the kg mol/h distillate: D=_______
(b) Calculate the kg mol/h bottoms:...

A distillation column should separate benzene and toluene in a
30 t/h feed flow containing 40 % benzene and 60 % toluene. The
overhead product should be 97 % benzene and bottom product 98 %
toluene. The molar reflux ratio RD = 3.5 and the saturated liquid
feed has a boiling point of 95 °C. Calculate flow rates of
distillate and bottom product . determine the number of ideal trays
needed for the separation . Where is the feed tray...

1. The liquid product
from a flash distillation has a mole fraction of the more volatile
component that is lower than the specified liquid purity. Should we
decrease, increase, or hold constant the vapor molar flowrate to
meet the specified liquid purity? Draw a sketch and explain
why?
2. If the
reflux ratio increases, do the molar flowrates for the distillate,
bottoms, reflux, and overhead vapor decrease, stay the same, or
increase? Support your answer.
3)1000 kmol/h of feed with...

We wish to separate a mixture of 60 mol% ethanol and 40 mol%
n-propanol in a distillation column with a partial
reboiler and a total condenser. The feed rate is 1000 kmol/h, and
feed is a saturated vapour. We desire a distillate product of 99
mol% ethanol and a bottoms product that is 0.8 mol% ethanol. Reflux
is saturated liquid and CMO can be used. Equilibrium data can be
approximated with an average relative volatility of 2.1 (ethanol is
more...

11. Your company has a distillation column ready to install. The
column has one feed, a
partial condenser and a partial reboiler. Vapor product is drawn
directly from the condenser.
Find the number of degrees of freedom with this column. HINT there
is no stream divider
after the condenser.
12. Using a total condenser with a reflux ratio of 2, the heat load
on the condenser is
(a) Twice the heat of vaporization of the distillate.
(b) Equal to the...

Minimum number of trays
100 kmol/hr of a feed of 60% benzene and 40% heptane is to be
separated by distillation. The distillate is to be 90% benzene and
the bottoms 10% benzene. The feed enters the column as 30 mol%
vapor. Use R 1.5 times the minimum. Assume a constant relative
voltaility of (alpha) of 4 and that the pressure is constant
throughout the column at 1atm.

A liq mixture of benzene-toluene is to be distilled in a
fractionating tower at 101.3 kPa pressure. The feed of 100 kg mol/h
is liq and it contains 45 mole % benzene and 55 mole % toluene and
enters at 327.6 K (130 ◦F). A distillate containing 95
mole % benzene and 5 mole % toluene and a bottoms containing 10
mole % benzene and 90 mole % toluene are to be obtained. The reflux
ratio is 4:1. The average...

A distillation column has a feed of 100 kmol/h. The feed is 15
mol% heavy non-key, 35 mol% heavy key, and 50 mol% light key. The
reflux ratio is 1.4 times the minimum. It is desired to have 99%
recovery of the light key in the distillate. The mole fraction of
light key in the distillate should be 0.85. Use the FUG approach to
determine the number of ideal stages required. Equilibrium
data:
aLNK =3.5
aLK =1.5
aHK =0.85

Fifty mol% methanol in water at 101 kPa is continuously
distilled in a seven-plate, perforated-tray column, with a total
condenser and a partial reboiler heated by steam. Normally 100
kmol/h of feed is introduced on the third plate from the bottom.
The overhead product contains 90 mol% methanol, and the bottoms 5
mol%. One mole of reflux is returned for each mole of overhead
product. Recently it has been impossible to maintain the product
purity in spite of an increase...

Separation Process:
Suppose a saturated liquid feed of a benzene (B)/toluene (T)
mixture (50 mol% B) to a column is to be separated into a high
purity distillate that is has a mole fraction of B equal to 0.9999
with a bottoms product mole fraction of 0.10. You may take the
relative volatility to be aBT = 2.49 at the temperature that the
column is operated. You are also given the reflux ratio to be 10.0,
assuming a total condenser....

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