Microsoft Word 321hw5_07'doc

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CHE321 TUTORIAL Homework 5
Question One 700lbmole/hr of feed is available
for separation at 1 atm. The feed contains 45
mol benzene and 55-mol toluene and enters a
column at its bubble point. Use the short cut
distillation column to find the number of trays
required for the separation at Reflux Ratio of
1.5 such that the distillate contains 92-mol
benzene and the bottoms 95-mol toluene. If
cold water is available at 19oC and steam is
available at 120oC, estimate the masses of water
and steam required for the condenser and reboiler
respectively. Question Two Toluene is
produced from n-heptane by dehydrogenation over a
Cr2O3 catalyst absorbed on Al2O3
CH3CH2CH2CH2CH2CH2CH3 C6H5-CH3 4H2 As
shown in the Fig., n-heptane is heated from 65 to
800 F in a SUPERHEATER and then fed to a
CATALYTIC REACTOR, which operates isothermally
and converts 17.5 mol of n-heptane to toluene.
Its effluent is cooled to 65F and fed to a
separator. The separator is used to remove
hydrogen from the reactor effluent. Assuming that
all the units operate at atmospheric pressure,
use CHEMCAD to determine the species flow
rate in every stream. The heat loads on
both the heater and the cooler. The reactor
load. Now use the shortcut distillation unit
to separate the resulting liquid effluent at the
exit conditions of the flash unit. State clearly
the number of stages required ( for R/Rmin
1.25 ) to achieve 99 mol toluene in the
product. What are the condenser and reboiler
duties required for this operation?