IntroductiontoAspenPlus--2014.pdf

Introduction to Aspen Plus
Speaker: Bor-Yih Yu(余柏毅)
Date: 2013/09/02
f00524023@ntu.edu.tw
PSE Laboratory
Department of Chemical Engineering
Nation Taiwan University
(綜合 room 402)
Edited by: 程建凱/吳義章/余柏毅

2
Part 1: Introduction

What is Aspen Plus
• Aspen Plus is a market-leading process modeling tool for
conceptual design, optimization, and performance monitoring
for the chemical, polymer, specialty chemical, metals and
minerals, and coal power industries.
3
Ref: http://www.aspentech.com/products/aspen-plus.cfm

What Aspen Plus provides
• Physical Property Models
– World’s largest database of pure component and phase equilibrium
data for conventional chemicals, electrolytes, solids, and polymers
– Regularly updated with data from U. S. National Institute of Standards
and Technology (NIST)
• Comprehensive Library of Unit Operation Models
– Addresses a wide range of solid, liquid, and gas processing equipment
– Extends steady-state simulation to dynamic simulation for safety and
controllability studies, sizing relief valves, and optimizing transition,
startup, and shutdown policies
– Enables you build your own libraries using Aspen Custom Modeler or
programming languages (User-defined models)
Ref: Aspen Plus® Product Brochure
4

More Detailed
• Properties analysis
– Properties of pure component and mixtures (Enthalpy,
density, viscosity, heat capacity,…etc)
– Phase equilibrium (VLE, VLLE, azeotrope calculation…etc)
– Parameters estimation for properties models (UNIFAC
method for binary parameters, Joback method for boiling
points…etc)
– Data regression from experimental deta
• Process simulation
– pump, compressor, valve, tank, heat exchanger, CSTR, PFR,
distillation column, extraction column, absorber, filter,
crystallizer…etc 5

What course Aspen Plus
can be employed for
• MASS AND ENERGY BALANCES
• PHYSICAL CHEMISTRY
• CHEMICAL ENGINEERING THERMODYNAMICS
• CHEMICAL REACTION ENGINEERING
• UNIT OPERATIONS
• PROCESS DESIGN
• PROCESS CONTROL
6

Lesson Objectives
• Familiar with the interface of Aspen Plus
• Learn how to use properties analysis
• Learn how to setup a basic process simulation
7

Outline
• Part 1 : Introduction
• Part 2 : Startup
• Part 3 : Properties analysis
• Part 4 : Running Simulation in Aspen Plus (simple units)
• Part 5 : Running Simulation in Aspen Plus (Reactors)
• Part 6 : Running Simulation in Aspen Plus (Distillation)
• Part 7 (additional): Running Simulation in Aspen Plus (Design,
spec and vary)
8

9
Part 2: Startup

Start with Aspen Plus
Aspen Plus User Interface

Interface of Aspen Plus
Process Flowsheet Windows
Model Library (View| Model Library )
Stream
Help
Setup
Components
Properties
Streams
Blocks
Data Browser
Next
Check Result
Stop
Reinitialize
Step
Start
Control Panel
Process Flowsheet Windows
Model Library (View| Model Library )
Status message
12

More Information
Help for Commands for Controlling Simulations 13

Data Browser
• The Data Browser is a sheet and form viewer with a
hierarchical tree view of the available simulation
input, results, and objects that have been defined
14

Setup – Specification
Run Type
Input mode
15

Input components
Remark: If available, are
16

Properties
Process type(narrow the number of
methods available)
Base method: IDEAL, NRTL, UNIQAC, UNIFAC…
17

Property Method Selection—General Rule
18
Example 1:
water - benzene
Example 2:
benzene - toluene

Typical Activity Coefficient Models
Non-Randon-Two Liquid Model (NRTL)
Uniquac Model
Unifac Model

Typical Equation of States
Peng-Robinson (PR) EOS
Redlich-Kwong (RK) EOS
Haydon O’Conell (HOC) EOS

Thermodynamic Model – NRTL
NRTL
21

NRTL – Binary Parameters
Click “NRTL” and then built-in binary parameters
appear automatically if available.
22

Access Properties Models and
Parameters
23
Review Databank Data

Review Databank Data
Description of each parameter
Including:
Ideal gas heat of formation at 298.15 K
Ideal gas Gibbs free energy of formation at
298.15 K
Heat of vaporization at TB
Normal boiling point
Standard liquid volume at 60°F
….
24

Pure Component
Temperature-Dependent Properties
CPIGDP-1 ideal gas heat capacity
CPSDIP-1 Solid heat capacity
DNLDIP-1 Liquid density
DHVLDP-1 Heat of vaporization
PLXANT-1 Extended Antoine Equation
MULDIP Liquid viscosity
KLDIP Liquid thermal conductivity
SIGDIP Liquid surface tension
UFGRP UNIFAC functional group
25

Example: PLXANT-1
(Extended Antoine Equation)
?
Corresponding Model
Click “↖?” and then click where you don’t know
26

Example: CPIGDP-1
(Ideal Gas Heat Capacity Equation)
?
Corresponding Model
27

Basic Input---Summary
• The minimum required inputs to run a simulation
are:
– Setup
– Components
– Properties
– Streams
– Blocks
Property Analysis
Process Simulation
28

29
Part 3: Property analysis

Overview of Property Analysis
Use this form To generate
Pure
Tables and plots of pure component properties as a function of temperature
and pressure
Binary Txy, Pxy, or Gibbs energy of mixing curves for a binary system
Residue Residue curve maps
Ternary
Ternary maps showing phase envelope, tie lines, and azeotropes of ternary
systems
Azeotrope
This feature locates all the azeotropes that exist among a specified set of
components.
Ternary Maps
Ternary diagrams in Aspen Distillation Synthesis feature: Azeotropes,
Distillation boundary, Residue curves or distillation curves, Isovolatility curves,
Tie lines, Vapor curve, Boiling point
30
***When you start properties analysis, you MUST specify components ,
thermodynamic model and its corresponding parameters. (Refer to Part 2)

Find Components
31
Component ID : just for distinguishing in Aspen.
Type : Conventional, Solid….etc
Component name : real component name
Formula : real component formula

Find Components
32
TIP 1: For common components, you can
enter directly the common name or molecular
equation of the components in “component
ID”.
(like water, CO2, CO, Chlorine…etc)

Find Components
33
TIP 2: If you know the component name
(like N-butanol, Ethanol….etc), you can
enter it in “component name”.

Find Components
34
TIP 3: You can also enter the formula of the
component. (Be aware of the isomers)
You can also click “Find” to search for
component of given CAS number,
molecular weight without knowing its
molecular formula, or if you don’t know the
exactly component name

Select Thermodynamic Model
35
Select NRTL

Check Binary Parameter
36
Click This, it will automatically change to
red if binary parameter exists.
Properties
Parameters
NRTL-1

Find Components
37
TIP 2: If you know the component name
(like N-butanol, Ethanol….etc), you can
enter it in “component name”.

Find Components
38
You can enter
the way of
searching…

Properties Analysis – Pure Component
39

Available Properties
Property (thermodynamic) Property (transport)
Availability Free energy Thermal conductivity
Constant pressure
heat capacity
Enthalpy Surface tension
Heat capacity ratio Fugacity coefficient Viscosity
Constant volume heat
capacity
Fugacity coefficient
pressure correction
Free energy departure Vapor pressure
Free energy departure
pressure correction
Density
Enthalpy departure Entropy
Enthalpy departure
pressure correction
Volume
Enthalpy of
vaporization
Sonic velocity
Entropy departure 40

Example1: CP (Heat Capacity)
1. Select property (CP)
2. Select phase
3. Select component
4. Specify range of temperature
5. Specify pressure
6. Select property method
7. click Go to generate the results
Add “N-butyl-acetate”
41

Example1: Calculation Results of CP
Data results 42

Properties Analysis – Binary Components

Binary Component Properties Analysis
Use this Analysis type To generate
Txy
Temperature-compositions diagram at
constant pressure
Pxy
Pressure-compositions diagram at
constant temperature
Gibbs energy of mixing
Gibbs energy of mixing diagram as a
function of liquid compositions. The
Aspen Physical Property System uses this
diagram to determine whether the
binary system will form two liquid phases
at a given temperature and pressure.

Example: T-XY
1. Select analysis type (Txy)
2. Select phase (VLE, VLLE)
2. Select two component
4. Specify composition range
5. Specify pressure
3. Select compositions basis

Example: calculation result of T-XY
Data results

Example: Generate XY plot
Click “plot wizard” to generate XY plot

Example: Generate XY plot (cont’d)

Properties Analysis – Ternary
(add one new components)

(Check NRTL binary parameter)
3 components -> 3 set of binary parameter
(How about 4 components??)

Ternary Map
4. Select phase (VLE, LLE)
1. Select three component
5. Specify pressure
2. Specify number of tie line
6. Specify temperature
(if LLE is slected)

Calculation Result of Ternary Map (LLE)
Data results

Property Analysis – Conceptual Design
Use this form To generate
Pure
Tables and plots of pure component properties as a function of temperature
and pressure
Binary Txy, Pxy, or Gibbs energy of mixing curves for a binary system
Residue Residue curve maps
Ternary
Ternary maps showing phase envelope, tie lines, and azeotropes of ternary
systems
Azeotrope
This feature locates all the azeotropes that exist among a specified set of
components.
Ternary Maps
Ternary diagrams in Aspen Distillation Synthesis feature: Azeotropes,
Distillation boundary, Residue curves or distillation curves, Isovolatility curves,
Tie lines, Vapor curve, Boiling point
54
(Optional)

Azeotrope Analysis
1. Select components (at least two) 2. Specify pressure
5. Select report Unit
6. click Report to generate the results

Error Message
Close analysis input dialog box (pure or binary analysis)

Ternary Maps
1. Select three components
2. Specify pressure
5. Select report Unit
6. Specify temperature of LLE
(If liquid-liquid envelope is selected)
6. Click Ternary Plot to generate the results

Ternary Maps
Ternary Plot Toolbar:
Add Tie line, Curve,
Marker…
Change pressure or
temperature

63
Part 4: Running simulation
Simple Units
(Mixer, Pump, valve, flash, heat exchanger)

Example 1: Calculate the mixing
properties of two stream
1
2
3
4
Mixer Pump
1 2 3 4
Mole Flow kmol/hr
WATER 10 0 ? ?
BUOH 0 9 ? ?
BUAC 0 6 ? ?
Total Flow kmol/hr 10 15 ? ?
Temperature C 50 80 ? ?
Pressure bar 1 1 1 10
Enthalpy kcal/mol ? ? ? ?
Entropy cal/mol-K ? ? ? ?
Density kmol/cum ? ? ? ?
64

Setup – Specification
Select Flowsheet
65

Reveal Model Library
View|| Model Library
or press F10
66

Adding a Mixer
Click “one of icons”
and then click again on the flowsheet window
Remark: The shape of the icons are meaningless
67

Adding Material Streams
Click “Materials” and then click
again on the flowsheet window
68

Adding Material Streams (cont’d)
When clicking the mouse on the flowsheet window,
arrows (blue and red) appear.
69

When moving the mouse on the arrows, some description appears.
Blue arrow: Water
decant for Free water
of dirty water.
Red arrow(Left) Feed
(Required; one ore more
if mixing material
streams)
Red arrow(Right):
Product (Required; if
mixing material streams)
70

After selecting “Material Streams”, click and pull a stream line.
Repeat it three times to generate three stream lines.
71

Reconnecting Material Streams
(Feed Stream)
Right Click on the stream and
select Reconnect Destination
72

Reconnecting Material Streams
(Product Stream)
Right Click on the stream and
select Reconnect Source
B1
1
2
3
73

Specifying Feed Condition
Right Click on the stream
and select Input
74

Specifying Feed Condition (cont’d)
1 2
75

Specifying Input of Mixer
Right Click on the block and select Input
76

Specifying Input of Mixer (cont’d)
Specify Pressure and valid phase
77

Run Simulation
Click ► to run the simulation
Check “simulation status”
“Required Input Complete” means the input is ready to run simualtion
Run Start or continue calculations
Step Step through the flowsheet one block at a time
Stop Pause simulation calculations
Reinitialize Purge simulation results
78

Status of Simulation Results
Message Means
Results available
The run has completed normally, and results are
present.
Results with warnings
Results for the run are present. Warning
messages were generated during the
calculations. View the Control Panel or History
for messages.
Results with errors
Results for the run are present. Error messages
were generated during the calculations. View the
Control Panel or History for messages.
Input Changed
Results for the run are present, but you have
changed the input since the results were
generated. The results may be inconsistent with
the current input.
79

Stream Results
Right Click on the block and
select Stream Results
80

1 2 3
Substream: MIXED
Mole Flow kmol/hr
WATER 10 0 10
BUOH 0 9 9
BUAC 0 6 6
Total Flow kmol/hr 10 15 25
Total Flow kg/hr 180.1528 1364.066 1544.218
Total Flow cum/hr 0.18582 1.74021 1.870509
Temperature C 50 80 70.08758
Pressure bar 2 1 1
Vapor Frac 0 0 0
Liquid Frac 1 1 1
Solid Frac 0 0 0
Enthalpy kcal/mol -67.81 -94.3726 -83.7476
Enthalpy kcal/kg -3764.03 -1037.77 -1355.82
Enthalpy Gcal/hr -0.6781 -1.41559 -2.09369
Entropy cal/mol-K -37.5007 -134.947 -95.6176
Entropy cal/gm-K -2.0816 -1.48395 -1.54799
Density kmol/cum 53.81564 8.619647 13.36534
Density kg/cum 969.5038 783.851 825.5604
Average MW 18.01528 90.93771 61.76874
Liq Vol 60F cum/hr 0.1805 1.617386 1.797886
Pull down the list and select
“Full” to show more properties
results.
81
Enthalpy and Entropy

Change Units of Calculation Results
82

Setup – Defining Your Own Units Set
83

Stream Results with Format of
Mole Fraction
85

Pump – Specification
2. Specify pump outlet specificatio
(pressure, power)
1. Select “Pump” or “turbine”
3. Efficiencies (Default: 1)
89

Run Simulation
Click ► to generate the results
Check “simulation status”
“Required Input Complete”
90

Block Results (Pump)
Right Click on the block and select Results
91

Calculation Results
(Mass and Energy Balances)
1
2
3
4
Mixer Pump
1 2 3 4
Mole Flow kmol/hr
WATER 10 0 10 10
BUOH 0 9 9 9
BUAC 0 6 6 6
Total Flow kmol/hr 10 15 25 25
Temperature C 50 80 70.09 71.20
Pressure bar 1 1 1 10
Enthalpy kcal/mol -67.81 -94.37 -83.75 -83.69
Entropy cal/mol-K -37.50 -134.95 -95.62 -95.46
Density kmol/cum 969.50 783.85 825.56 824.29
94

Exercise
1
2 4
6
Mixer Pump
3
5
1 2 3 4 5 6
Mole Flow kmol/hr
Water 10 0 0 ? ? ?
Ethanol 0 5 0 ? ? ?
Methanol 0 0 15 ? ? ?
Total Flow kmol/hr 10 15 15 ? ? ?
Temperature C 50 70 40 ? ? ?
Pressure bar 1 1 1 1 4 2
Enthalpy kcal/mol ? ? ? ? ? ?
Entropy cal/mol-K ? ? ? ? ? ?
Density kmol/cum ? ? ? ? ? ?
95
Please use Peng-Robinson EOS to solve this problem.

Example 2: Flash Separation
Saturated Feed
P=1atm
F=100 kmol/hr
zwater=0.5
zHAc=0.5
T=105 C
P=1atm
What are flowrates and compositions of the two outlets?
0.0 0.2 0.4 0.6 0.8 1.0
100
105
110
115
120
T
(
o
C) xWater
and yWater
T-x
T-y

T-xy plot
1. Select analysis type (Txy) 2. Select phase (VLE, VLLE)
2. Select two component
4. Specify composition range
5. Specify pressure
3. Select compositions basis

Calculation Result of T-xy
Data results

Specify Feed Condition
Saturated Feed
(Vapor fraction=0)
P=1atm
F=100 kmol/hr
zwater=0.5
zHAc=0.5

Flash2: Specification
T=105 C
P=1atm

Required Input Complete
Click ► to run simulation
**Before running simulation, property
analysis should be closed.

Stream Results (cont’d)
Saturated Feed
P=1atm
F=100 kmol/hr
zwater=0.5
zHAc=0.5
T=105 C
P=1atm
42.658 kmol/hr
zwater=0.501
zHAc=0.409
57.342 kmol/hr
zwater=0.432
zHAc=0.568

HEAT EXCHANGE
熱物流
入口温度：200℃、入口壓力：0.4 MPa
流量：10000kg/hr
组成：苯 50%，苯乙烯 20%，水 10%
冷卻水
入口温度：20℃、入口压力：1.0 MPa
流量：60000 kg/hr。
熱流出口氣相分率為 0
（飽和液相）

116
COMPONENTS – SPECIFICATION

117
Thermodynamic Model – NRTL

Feeds Conditions
HOT-IN
CLD-IN

123
Reactor Systems
(RGIBBS, RPLUG,RCSTR)

124
Equilibrium Reactor: RGIBBS
1. Reaction Kinetics are unknown.
2. There are lots of products
RGIBBS unit predicts the product by
minimizing GIBBS energy in the system
It is very Useful When…:

125
2
2
2
2
4
2
2
2
4
2
2
4
3
H
CO
O
H
CO
O
H
CH
H
CO
O
H
CH
H
CO









Reactions:
Fresh Feed
Flow rate 1000 (kmol/h)
CO 0.2368
H2 0.7172
H2O 0.0001
CH4 0.0098
CO2 0.0361
T=300 k
P=470 psia

126

Inside the Block:

KINETICS REACTORS: RPLUG
Reaction :Exothermic & reversible
2
2
2 H
CO
O
H
CO 

 )
/
(
09
.
41 mol
KJ
H 


)
85458
exp(
1
.
3922
)
47400
exp(
545
.
51
)
(
2
2
2
RT
k
RT
k
s
kgcat
kmol
Y
Y
k
Y
Y
k
Rate
r
f
H
CO
r
O
H
CO
f







Rate [=] Kmol/Kgcat/s
Activation Energy [=] KJ/Kmol

Reaction :Exothermic & reversible
2
2
2 H
CO
O
H
CO 

 )
/
(
09
.
41 mol
KJ
H 


Catalyst Loading = 0.1865 Kg
Bed Voidage = 0.8928
Feed Temperature = 583K
Feed Pressure = 1 bar
Reactor Length = 10 m
Reactor Diameter = 5m
Fresh Feed
Flow rate 200 (mol/h)
CO 0.030
H2 0.430
H2O 0.392
CO2 0.148

Feed Stream:

Reaction Setting:

RPLUG Setting:

139
Check result
Select Reactor Length column
Plot -> x-Axis variable
Select Temperature Column
Plot -> y-Axis variable
Display Plot

140
Check result
Block B2 (RPlug) Profiles Process Stream
Reactor length MIXED meter
TEMPERATURE
K
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0
585.0
587.5
590.0
592.5
595.0
597.5
600.0
602.5
605.0
607.5
Temperature MIXED

142
Check result
Select Reactor Length column
Plot -> x-Axis variable
Select all other columns
Plot -> y-Axis variable
Display Plot

Check result
Block B2 (RPlug) Profiles Process Stream
Reactor length MIXED meter
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Mole fraction MIXED CO
Mole fraction MIXED H2O
Mole fraction MIXED CO2
Mole fraction MIXED H2

KINETICS REACTORS: RCSTR
Reaction :Exothermic & Irreversible
Aniline + Hydrogen  Cyclohexylamine (CHA)
C6H7N + 3H2  C6H13N

Reactor Conditions
Reactor :
Reactor
condition
Reactor type
Reactor liquid level
595 psi
250 F
1200 ft3
Temperature
Volume
Vertical cylindrical vessel
80%
Pressure

Reaction Kinetics
CHA R A H
R kV C C

8
0 10
k 
0 exp( )
E
k k
RT


3
lbmole
ft
Reaction rate :
Where
VR: reactor volume
CA: concentration of Aniline
CH: concentration of Hydrogen
• Reaction kinetics :
Where
E : activity energy
T : temperature (R)
2000Btu
E
lbmole

3
lbmole
ft
3
ft

Feeds Conditions
1
100 lbmolhr 1
400 lbmolhr
Two fresh feed stream :
Aniline feed Hydrogen feed
mole rate
temperature
pressure
100 F 100 F
650 psia 650 psia

153
Check result
(1) Compare the conversion between RSTOIC and RCSTR.
(2) Compare the net duty inside the RSTOIC and RCSTR
Question:

154
Distillation Process
(DSTWU, RADFRAC)

1
2
39
Saturated Feed
P=1.2atm
F=100 kmol/hr
zwater=0.5
zHAc=0.5
xwater=0.99
xHAc=0.99
40
20
Distillation Separation
• There are two degrees of
freedom to manipulate
distillate composition and
bottoms composition to
manipulate the distillate and
bottoms compositions.
• If the feed condition and the
number of stages are given,
how much of RR and QR are
required to achieve the
specification.
RR ?
QR ?

Distillation Separation
Example :
A mixture of benzene and toluene containing 40 mol% benzene
is to be separated to dive a product containing 90 mol%
benzene at the top, and no more than 10% benzene in bottom
product. The feed enters the column as saturated liquid, and
the vapor leaving the column which is condensed but not
cooled, provide reflux and product. It is proposed to operate
the unit with a reflux ratio of 3 kmol/kmol product. Please
find:
(1) The number of theoretical plates.
(2) The position of the entry.
(Problem is taken from Coulson & Richardson’s Chemical
Engineering, vol 2, Ex 11.7, p.564)

1. By what you learned in Material balance and
unit operation
1
Saturated Feed
P=100 Kpa
F=100 kmol/hr
xben=0.4
xtol=0.6
xben=0.9
xben<0.1
n
From Overall Material Balance:
100 = D+B
From Benzene Balance:
100*0.4 = 0.9 * D+ 0.1* B
Thus, D=37.5 and B=62.5.
37.5
62.5

1. By what you learned in Material balance and
unit operation
From thermodynamic phase equilibrium, and the calculation of operating line:
We can get the number of theoretical plate to be 7.

2. By the shortcut method in Aspen Plus (DISTWU)
(Add components)
Built in the components

(Select property method)
Select NRTL

(Select property method)
Check the binary parameters

2. By the shortcut method in Aspen Plus (DSTWU)
Add the unit “DSTWU”
The red arrows are the required material stream!

Connect the required material stream

“Feed1” Stream specification

2. By the shortcut method in Aspen Plus
(Column Specification)
From the problem Assume no pressure drop
Inside the column

Light Key recovery
= (mol of light component in distillate) /
(mol of light component in feed)
= (37.5*0.9)/(100*0.4)
= 0.84375

Heavy Key recovery
= (mol of heavy component in distillate)
/ (mol of heavy component in feed)
= (37.5*0.1)/(100*0.6)
= 0.0625

Get results by varying the
number of stages. (Initial
Guess)

RUN THE SIMULATION

(Stream Results)
Click right button on the unit, and select “Stream
Results”

(Stream Results)
The required product
quality

(RR vs number of stage)
For RR=3, at least 7
theoretical stages are
required.

3. More rigorous method in Aspen Plus (RADFRAC)
Add the unit “RADFRAC”
The red arrows are the required material stream!

Connect the required material stream

(Feed Specification)
Same as Case 2

Double click left button on the unit….

RR=3 from the problem, distillate rate = 37.5
(kmol/h) from previous calculation
7 stages from previous
calculation.

Specify the feed stage.

Specify the pressure at the top of column

(Calculation of tray size—Tray Sizing)

(Calculation of tray size—Tray Sizing)
*Calculation from 2th tray from the top to
2th tray from the bottom. (WHY??)
*Select a tray type.

(Pressure drop calculation– Tray Rating)

(Pressure drop calculation– Tray Rating)
*Calculation from 2th tray from the top to
2th tray from the bottom. (WHY??)
*Initial guess of the tray size

(Stream Results)
Click right button on the unit, and select “Stream
Results”

(Stream Results)
Different from the shorcut method.
(WHY??)

187
(Additional)
Design, spec, and vary in RADFRAC

(Design , Spec and Vary)

What do we want??
--- 90% Benzene at top.
Select “Mole Purity”…

What do we want??
--- 90% Benzene at top.
And the target is 0.9.

Select “Benzene”

Select the distillate stream

Add a Vary
(1 Design Spec 1 Vary)

Varying Reflux ratio to
reach the design target.

Specify the varying range.
(Should contain the initial value)

2nd Design Spec

What do we want??
--- 10% Benzene at bot.

What do we want??
--- 10% Benzene at bot.
And the target is 0.1.

Select the Benzene

Select the bottom stream

2nd Vary

Varying distillate rate to
reach the design target.
Specify the varying range.
(Should contain the initial value)

RUN THE SIMULATION,
and click right button on
the unit, select “Stream
results”

(Stream Results)
The required product
quality

(Column Results--top)
Calculated Reflux Ratio = 6.14
(from problem: 3)

(Column Results--bottom)
The required heat duty for
separation is 2341.8 (KW)

(Profile Inside the Column)
T : Temperature
P : Pressure
F : Liquid and vapor flow rate.
Q: Heat Duty

(Profile Inside the Column)
You can select the vapor or
liquid composition profile.
(also in mole or mass basis)

(Plotting Temp. Profile)
Select the column “Stage”
Click “Plot”
Select “X-axis variable”

Select the column “Temp.”
Click “Plot”
Select “Y-axis variable”

Then, select “Display
Plot”

Exercise
Example:
Typically, 90 mol% product purity is not enough for a product to
sale. In the same problem, assume the number of stages
increase to 10. Try the following exercises:
(1) Is it possible to separate the feed to 95 mol% of benzene in
the distillate, and less than 5% of benzene in the bottom
product? If yes, what is the RR and Qreb?
(2) As in (1), is it possible to separate the feed to 99 mol% of
benzene in the distillate, and less than 1% of benzene in the
bottom product? If yes, what is the RR and Qreb?
(3) As in (2), if no, how many number of stages is required to
reach this target?
(Hint: Use design, spec, and vary to do this problem)

214
Thanks for your attention!
PSE Laboratory
Department of Chemical Engineering
Nation Taiwan University
(綜合 room 402)

IntroductiontoAspenPlus--2014.pdf

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