Process Design & Simulation_ASPEN_HYSIS -- 2
Budget: $66 – $99 USD
Process Design & Simulation
You have been asked by your employer to investigate the initial design of a continuous distillation
column to separate Toluene (C7H8) and Chlorobenzene (C6H5Cl). Your employer has suggested you
work from a basis of a feed stream with a composition of 30 mol % toluene, and flow of 1000 kg/hr.
The column is expected to produce a toluene product stream containing not more than 3 mol%
chlorobenzene, and similarly not more than 1 mol% toluene should be present in the chlorobenzene
product stream.
You are expected to:
Determine the vapour liquid equilibria for the system
Perform hand calculations to initially determine
o The minimum reflux ratio.
o Number of ideal stages in the column.
o Location of the feed tray for the column
o Condenser and Reboiler energy duties in kW.
Use the shortcut distillation unit op in ASPEN HYSYS to verify the hand calculations.
Use the distillation unit op in ASPEN HYSYS to analyse the separation and suggest
recommended operating parameters for the column and location for the feed.
Determining the vapour liquid equilibria for the system.
Using the Antoine Constants provided in Table 1, generate the vapour liquid equilibria data for
mixtures of Chlorobenzene and Toluene under a system pressure of 2 atmospheres.
Important: You should state any assumptions you make clearly
Initial calculations to determine minimum reflux ratio and number of ideal stages.
Using the vapour liquid equilibria (VLE) data that you have generated; you should apply the McCabe
Thiele Method to determine the minimum reflux ratio for the column and for an assumed reflux ratio,
determine the number of ideal stages required to achieve the separation and the location of the feed
tray.
Important: You should state any assumptions you make clearly.
Nomenclature
N = number of stages in column, (the reboiler is considered a stage)
Nmin = minimum number ofstages in column
Nr = number of stages above the feed, including any partial condenser
Ns = number of stages below the feed, including the reboiler.
R = reflux ratio.
Rmin = minimum reflux ratio
XA = mole faction of most volatile component
XB = mole fraction of least volatile component
α = average relative volatility of component A with respect to component B
D = Distillate product molar flow in kmol h-1
W = Bottom product molar flow in kmol h
Subscripts F, D, W refer to feed, distillate and bottom product respectively.
Compare the values from the McCabe Thiele Method and Shortcut Calculations. Discuss if the values
are in agreement, suggest reasons for any differences.
Condenser and Reboiler Duties
For the reflux ratio that you have chosen; perform an energy balance over the distillation unit
operation and determine the condenser and reboiler duties in kW.
Important: You will need find relevant thermodynamic data to perform these calculations. Clearly
state any assumptions that you make, and cite all sources that you have used.
Verification of hand calculations by simulation in ASPEN HYSYS
You will now use ASPEN HYSYS to simulate the separation, verify your hand calculations and then
analyse the separation. You will do this using the ‘Shortcut Distillation Unit Operation’ and the
‘Distillation Column Unit Operation’.
Shortcut Distillation Unit Operation
Open a new ASPEN HYSYS casefile.
Input your component and select a suitable ‘fluid package’ to model the thermodynamics.
Generate your flowsheet and model the separation using the ‘Shortcut Distillation Unit Operation’.
Think carefully aboutthe inputs you provide and the parameters you specify within the unit operation.
Analysis of simulation results
Clearly show the performance results you have obtained from the simulation and discuss how the
values that have been generated compare with values obtained from your hand calculations. Do you
have confidence in the results provided by the simulation?
You have been asked by your employer to investigate the initial design of a continuous distillation
column to separate Toluene (C7H8) and Chlorobenzene (C6H5Cl). Your employer has suggested you
work from a basis of a feed stream with a composition of 30 mol % toluene, and flow of 1000 kg/hr.
The column is expected to produce a toluene product stream containing not more than 3 mol%
chlorobenzene, and similarly not more than 1 mol% toluene should be present in the chlorobenzene
product stream.
You are expected to:
Determine the vapour liquid equilibria for the system
Perform hand calculations to initially determine
o The minimum reflux ratio.
o Number of ideal stages in the column.
o Location of the feed tray for the column
o Condenser and Reboiler energy duties in kW.
Use the shortcut distillation unit op in ASPEN HYSYS to verify the hand calculations.
Use the distillation unit op in ASPEN HYSYS to analyse the separation and suggest
recommended operating parameters for the column and location for the feed.
Determining the vapour liquid equilibria for the system.
Using the Antoine Constants provided in Table 1, generate the vapour liquid equilibria data for
mixtures of Chlorobenzene and Toluene under a system pressure of 2 atmospheres.
Important: You should state any assumptions you make clearly
Initial calculations to determine minimum reflux ratio and number of ideal stages.
Using the vapour liquid equilibria (VLE) data that you have generated; you should apply the McCabe
Thiele Method to determine the minimum reflux ratio for the column and for an assumed reflux ratio,
determine the number of ideal stages required to achieve the separation and the location of the feed
tray.
Important: You should state any assumptions you make clearly.
Nomenclature
N = number of stages in column, (the reboiler is considered a stage)
Nmin = minimum number ofstages in column
Nr = number of stages above the feed, including any partial condenser
Ns = number of stages below the feed, including the reboiler.
R = reflux ratio.
Rmin = minimum reflux ratio
XA = mole faction of most volatile component
XB = mole fraction of least volatile component
α = average relative volatility of component A with respect to component B
D = Distillate product molar flow in kmol h-1
W = Bottom product molar flow in kmol h
Subscripts F, D, W refer to feed, distillate and bottom product respectively.
Compare the values from the McCabe Thiele Method and Shortcut Calculations. Discuss if the values
are in agreement, suggest reasons for any differences.
Condenser and Reboiler Duties
For the reflux ratio that you have chosen; perform an energy balance over the distillation unit
operation and determine the condenser and reboiler duties in kW.
Important: You will need find relevant thermodynamic data to perform these calculations. Clearly
state any assumptions that you make, and cite all sources that you have used.
Verification of hand calculations by simulation in ASPEN HYSYS
You will now use ASPEN HYSYS to simulate the separation, verify your hand calculations and then
analyse the separation. You will do this using the ‘Shortcut Distillation Unit Operation’ and the
‘Distillation Column Unit Operation’.
Shortcut Distillation Unit Operation
Open a new ASPEN HYSYS casefile.
Input your component and select a suitable ‘fluid package’ to model the thermodynamics.
Generate your flowsheet and model the separation using the ‘Shortcut Distillation Unit Operation’.
Think carefully aboutthe inputs you provide and the parameters you specify within the unit operation.
Analysis of simulation results
Clearly show the performance results you have obtained from the simulation and discuss how the
values that have been generated compare with values obtained from your hand calculations. Do you
have confidence in the results provided by the simulation?