Problem SM.4 Questions
your_name
date
1. As with column C3 in Problem SM.3, you must first compare the normal boiling points and
composition of all chemical components leaving the decanter in the organic stream. What are the
normal boiling points (nbp) for all of those chemical components? What are their mole fractions?
List the components and their nbp in order of increasing boiling point in the first two columns of
the table below, using the data found in the “Flowsheet Thermodynamic Data” section of Chapter
1 in this HYSYS manual. Then, list the mole fractions of the same chemical components in the
third column of the table.
Chemical
Component
Tnbp, C
at 1 atm
Mole Fractions in
Stream S14 for Reactor
R1 Inlet of ________°C
hydrogen
methanol
water
toluene
ethylbenzene
styrene monomer
2. Furthermore, you are to complete the fourth and fifth columns in the above table. What is the
feed type of each chemical component, i.e. state whether each component is a LK, HK, non-LK,
or non-HK? What is the qualitative distribution of each component? State which stream or
streams (i.e., distillate and/or bottoms) the chemical component appears in, and in what relative
amount, such as all, most or little. If necessary, refer to the Problem SM.3 handout to refresh
your memory about the concept of key and non-key components. Remember that the column is
being designed to separate the reactants from the products.
Chemical
Component
Tnbp, C
at 1 atm
Feed Type
Distribution
hydrogen
methanol
water
toluene
ethylbenzene
styrene monomer
3. Column C1 is depicted on the next page. What is the functional form for the HYSYS
simulation algorithm for this column, based on knowing the mole fraction of the heavy-key
component in the distillate stream? Define each of the variables in this functional form (HINT:
Refer to the Problem SM.3 assignment).
 V ,  D ,  B , QPC , QR   rcolumn____   F , PPC , PPC , PR , PR , N S , N FS , R, z D , HK , VRPC 
where QPC is the ____________ energy rate or heat duty, Q R is the ____________ energy rate or
heat duty, Pu is the pressure of the partial ____________ or ____________ unit, Pu is the
pressure drop across the partial ____________ or ____________ unit, N S is the number of
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your_name
Problem SM.4 Questions
date
____________ stages, NFS is the ____________ stage number, R is the ____________, z D , HK is the
total mole fraction of the ____________ in the distillate, and VRPC is the vent ratio for the partial
____________. The vector i is a short notation to represent the temperature, pressure, flow rate,
and molar composition (i.e., total mole fractions) of Stream i.
4. How might the value for the vent ratio be estimated?
vent ratio 
flow rate sum of all non-condensables in the feed
total flow rate of the feed
vent ratio 
________ kgmol / h in Stream S 22

________ kgmol / h in Stream S 22
A value one-hundred times greater like 1×10-2 should be used for the vent ratio of the
condenser vapor stream, because this value is less likely to constrain the iterative process that
converges the material and energy balances of the distillation column. A stricter vent ratio
like 1×10-3 will lead to an iteration error of “two liquid phases were found on the condenser
stage.” Using 1×10-2 eliminates this error.
What are the composition profiles of just the LK and HK in the distillation column?
Use the Performance/Plots page to print these profiles. Note that toluene is the light key
and ethylbenzene is the heavy key in this problem.
Below is the composition profile of toluene and ethylbenzene for a reactor inlet temperature of
________°C.
Use Snipping Tool to copy and paste graph here.
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