Introduction to Aspen Plus --2014.pdf

Introduction to Aspen Plus

Speaker: Bor-Yih Yu(余柏毅)

Date: 2013/09/02

[email protected]

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

http://www.aspentech.com/brochures/Aspen_Plus.pdf

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

Aspen Plus Startup

11

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)

Properties Analysis – Ternary (Check NRTL binary parameter)

3 components -> 3 set of binary parameter

(How about 4 components??)

Properties Analysis – Ternary

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)

Conceptual Design

Azeotrope Analysis

Azeotrope Analysis

4. Select phase (VLE, LLE)

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)

Azeotrope Analysis Report

Ternary Maps

Ternary Maps

4. Select phase (VLE, LLE) 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

23

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

Setup – Report Options

84

Stream Results with Format of Mole Fraction

85

Add Pump Block

86

Add A Material Stream

87

Connect Streams

88

Pump – Specification

2. Specify pump outlet specification

(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

92

Streams Results

93

Calculation Results (Mass and Energy Balances)

1

23

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 46

Mixer Pump3

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 1.0100

105

110

115

120

T (

oC

)x

Water and y

Water

T-x

T-y

Input Components

Thermodynamic Model: NRTL-HOC

Check Binary Parameters

Association parameters of HOC

Binary Parameters of NRTL

Binary Analysis

T-xy plot

1. Select analysis type (Txy) 2. Select phase (VLE, VLLE)

2. Select two component

4. Specify composition range

5. Specify pressure

6. Select property method 3. Select compositions basis


Calculation Result of T-xy

Data results

Generate xy plot

Generate xy plot (cont’d)

Add Block: Flash2

Add Material Stream

Specify Feed Condition

Saturated Feed

(Vapor fraction=0)

P=1atm

F=100 kmol/hr

zwater=0.5

zHAc=0.5

Block Input: Flash2

Flash2: Specification

T=105 C

P=1atm

Required Input Complete

Click ► to run simulation

**Before running simulation, property

analysis should be closed.

Stream Results

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

ADD BLOCK: HEATX

Feeds Conditions

HOT-IN CLD-IN

BLOCK INPUT

121

Check result

122

Check result

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


222

2422

242

24

3

HCOOHCO

OHCHHCO

OHCHHCO

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:

128

Check result

KINETICS REACTORS: RPLUG

Reaction :Exothermic & reversible

222 HCOOHCO )/(09.41 molKJH

)85458

exp(1.3922

)47400

exp(545.51

)(222

RTk

RTk

skgcat

kmolYYkYYkRate

r

f

HCOrOHCOf

Rate [=] Kmol/Kgcat/s

Activation Energy [=] KJ/Kmol


Reaction :Exothermic & reversible

222 HCOOHCO )/(09.41 molKJH

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:


Reaction Setting:


RPLUG Setting:


RPLUG Setting:


RPLUG Setting:

137

Check result

138

Check result

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

TE

MP

ER

AT

UR

E 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

58

5.0

58

7.5

59

0.0

59

2.5

59

5.0

59

7.5

60

0.0

60

2.5

60

5.0

60

7.5

Temperature MIXED

141

Check result

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

0.0

50

.10

.15

0.2

0.2

50

.30

.35

0.4

0.4

50

.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

Reactor Conditions Input

Reaction Kinetics

CHA R A HR kV C C

8

0 10k

0 exp( )Ek kRT

3lbmole

ft

Reaction rate :

Where

VR: reactor volume

CA: concentration of Aniline

CH: concentration of Hydrogen

• Reaction kinetics :

Where

E : activity energy

T : temperature (R) 2000 BtuE

lbmole

3lbmole

ft

3ft

Reaction Kinetics Input



Feeds Conditions

1100 lbmolhr1400 lbmolhr

Two fresh feed stream :

Aniline feed Hydrogen feed

mole rate

temperature

pressure

100 F 100 F

650 psia 650 psia

Feeds Conditions

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

2. By the shortcut method in Aspen Plus (DISTWU) (Select property method)

Select NRTL

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

2. By the shortcut method in Aspen Plus (Stream Results)

Click right button on the unit, and select “Stream

Results”

2. By the shortcut method in Aspen Plus (Stream Results)

The required product

quality

2. By the shortcut method in Aspen Plus (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!

3. More rigorous method in Aspen Plus (RADFRAC)

Connect the required material stream

3. More rigorous method in Aspen Plus (RADFRAC) (Feed Specification)

Same as Case 2

3. More rigorous method in Aspen Plus (RADFRAC) (Column Specification)

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

3. More rigorous method in Aspen Plus (RADFRAC) (Calculation of tray size—Tray Sizing)

3. More rigorous method in Aspen Plus (RADFRAC) (Calculation of tray size—Tray Sizing)

*Calculation from 2th tray from the top to

2th tray from the bottom. (WHY??)

*Select a tray type.

3. More rigorous method in Aspen Plus (RADFRAC) (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


3. More rigorous method in Aspen Plus (RADFRAC) (Stream Results)

Click right button on the unit, and select “Stream

Results”


Different from the shorcut method.

(WHY??)

187



(Additional)

Design, spec, and vary in RADFRAC

3. More rigorous method in Aspen Plus (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”


The required product

quality

3. More rigorous method in Aspen Plus (RADFRAC) (Column Results--top)

Calculated Reflux Ratio = 6.14

(from problem: 3)

3. More rigorous method in Aspen Plus (RADFRAC) (Column Results--bottom)

The required heat duty for

separation is 2341.8 (KW)

3. More rigorous method in Aspen Plus (RADFRAC) (Profile Inside the Column)

T : Temperature

P : Pressure

F : Liquid and vapor flow rate.

Q: Heat Duty

3. More rigorous method in Aspen Plus (RADFRAC) (Profile Inside the Column)

You can select the vapor or

liquid composition profile.

(also in mole or mass basis)

3. More rigorous method in Aspen Plus (RADFRAC) (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)

Documents

Introduction to Aspen Plus --2014.pdf