Gettingstarted Building and Running

8/2/2019 Gettingstarted Building and Running

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Building and Runninga Process Model

S T E A D Y S T A T E S I M U L A T I O N

10

AspenTec

Vers

ion

G E T T I N G S T A R T E D

Aspen Plus 7


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COPYRIGHT 19811999 Aspen Technology, Inc.ALL RIGHTS RESE RVED

The flowsheet gra phics an d plot componen ts of Aspen P lus wer e developed by MY-Tech, Inc.

Aspen Aerotran, Aspen Pin ch

, ADVENT

, Aspen B-JAC

, Aspen Cus tom Modeler

, Aspen

Dynamics, Aspen Hetra n

, Aspen P lus

, AspenTech

, B-JAC

, BioProcess Simulator (BPS)

,

DynaPlus, ModelMana ger

, Plan telligence

, th e Pla nt elligence logo

, Polymers Plus

, Pr operties

Plus, SPEEDUP

, and th e aspen leaf logo

ar e eith er registered tra demar ks, or tr adema rks of Aspen

Technology, Inc., in the United States and/or other countries.

BATCHFRAC

and RATEFRAC

ar e tr adema rks of Koch Engineering Compa ny, Inc.

Activator is a trademark of Software Security, Inc.

Rainbow SentinelSuperPr o

is a t ra dema rk of Rain bow Techn ologies, Inc.

lan License Manager is a trademark of lan Computer Group, Inc., Mountain View, California, USA.

Microsoft Windows, Windows NT, Windows 95 and Windows 98 are eith er r egistered t ra dema rk s ortr adema rks of Microsoft Corporat ion in th e Un ited Sta tes a nd/or other coun tr ies.

All oth er bran d and pr oduct nam es are tr adema rks or registered tr adema rks of th eir respectivecompanies.

The License Ma na ger portion of th is product is based on:

lan License Man ager

1989-1997 lan Compu ter Group, In c.All right s reser ved

Use of Aspen P lus an d This Manu al

This ma nua l is intended a s a guide to using Aspen P lus process modeling software. This documen tat ion conta ins

AspenTech proprietary and confidential information and may not be disclosed, used, or copied without the prior

consen t of AspenTech or a s set forth in th e applicable license agreem ent . Users a re solely responsible for the

proper use of Aspen P lus an d th e application of the results obtained.

Although AspenTech h as t ested th e software an d reviewed th e documenta tion, th e sole warra nty for Aspen Plus

may be found in th e applicable license agreemen t between AspenTech a nd the user. ASPEN TECH MAKES NO

WARRANTY OR REP RESEN TATION, EITHER EXPRESS OR IMPLIED, WITH RES PE CT TO THIS

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Building and Running a Process Model iiVersion 10.1-0

Contents

About Getting Started Building and Run ning a Proce ss Model

Why Us e Pr ocess Simu lat ion?........................................................................................vii

Wha t is an Aspen Plu s Pr ocess Simu lation Model?.................................................... viii

Sess ions in th is Book .......................................................................................................ix

For More In form at ion ......................................................................................................ix

Techn ical Su ppor t ............................................................................................................. x

1 Aspe n Plu s Bas ics

St ar tin g Aspen Plus .......................................................................................................1-2

The Aspen Plu s Main Window ......................................................................................1-2

Open ing a File ................................................................................................................1-3

Selecting Flowsheet Objects ...........................................................................................1-6

Us ing a Sh ortcu t Menu .................................................................................................1-7

Open ing In pu t For ms ....................................................................................................1-8

Us ing Help .....................................................................................................................1-9

En ter ing Da ta on a Form .............................................................................................1-11

Exper t Guida ncethe N ext F un ction .........................................................................1-12Runn ing th e Sim ula tion ..............................................................................................1-16Examining Stream and Block Results........................................................................1-17Modifying an d Reru nn ing Your Model ........................................................................1-19Exitin g Aspen Plus .......................................................................................................1-20

2 B u il di n g an d Ru n n i ng a P ro c e ss S im u la ti on Mo d e l

Building th e Pr ocess Model ...........................................................................................2-2Defining the Problem: Methylcyclohexane Recovery Column ....................................2-2St ar tin g Aspen Plu s.......................................................................................................2-3Cr eat ing a New Sim ula tion ...........................................................................................2-3The Aspen Plu s Main Window ......................................................................................2-4Defining th e Flowsh eet ..................................................................................................2-5Adding Da ta to t he Pr ocess Model..............................................................................2-11Specifying Title, Stream Properties, and Units .........................................................2-13En ter ing Compon ent s ..................................................................................................2-14

Selectin g Th erm odyna m ic Meth ods............................................................................2-16En ter ing St rea m Da ta .................................................................................................2-18Entering Unit Operation Block Data .........................................................................2-20Runn ing th e Sim ula tion ..............................................................................................2-25Exa min ing Sim ula tion Resu lts ...................................................................................2-26Exa min ing Block Resu lts ............................................................................................2-26Exa min ing St rea m Resu lts .........................................................................................2-29Chan ging In pu t Specificat ions....................................................................................2-30Rer un nin g t he Sim ula tion ...........................................................................................2-31


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iv Building and Running a Process ModelVersion 10.1-0

Creat ing Report s ......................................................................................................... 2-32

Exit ing Aspen Plus ...................................................................................................... 2-33

3 P e rfo rm i n g a Se n s it iv it y An a ly s is

St ar tin g Aspen Plu s ...................................................................................................... 3-2Open ing an Existin g Simu lation ................................................................................... 3-2

Saving a Simu lation un der a New Na me .................................................................... 3-3

Defining th e Sens itivity Analysis .................................................................................. 3-4

En ter ing Sensit ivity Specifications ............................................................................... 3-4

Defining Sam pled Var iables .................................................................................. 3-5

Defining Man ipu lat ed Var iables ........................................................................... 3-9

Defining Tabu lat ed Var iables .............................................................................. 3-11

Run nin g t he Simu lat ion .............................................................................................. 3-14

Displa ying Sensit ivity Ana lysis Resu lts .................................................................... 3-15

Plotting Sensit ivity Result s ......................................................................................... 3-16

Exitin g Aspen Plus ...................................................................................................... 3-17

4 Me e ti n g P r oc e s s D e s ig n Sp e c ifi c at io n s

Sta rt ing Aspen Plus....................................................................................................... 4-2

Open ing an E xistin g Sim ula tion .................................................................................. 4-2

Saving a Simulat ion Un der a New Na me ..................................................................... 4-3

Defining th e Design Specificat ion ................................................................................. 4-4

En ter ing Design Specificat ions ..................................................................................... 4-4

Run nin g t he Simu lation ................................................................................................ 4-9

Exa min ing Design Specificat ion Resu lts .................................................................... 4-10


5 Cr ea ti ng a P ro ce s s F lo w D ia gra m


Open ing an Existin g Simu lation ................................................................................... 5-2

Switching to PF D Mode ................................................................................................. 5-3

Adding Equipm ent Icons an d Strea ms ......................................................................... 5-4

Displaying Str eam Dat a ................................................................................................ 5-8

Adding a St rea m Tab le ............................................................................................... 5-11

Adding Text ................................................................................................................. 5-13

Pr intin g a Pr ocess F low Diagr am ................................................................................ 5-15

Leaving PF D Mode...................................................................................................... 5-16


6 E sti mati ng P hys ica l P roper ti e s for a Non-Databank Component

Thiazole Ph ysical Pr operty Dat a ................................................................................... 6-2


Crea ting a Pr operty Est imat ion Simu lation ............................................................... 6-3

En ter ing Componen ts In form at ion ............................................................................... 6-4

Specifying P ropert ies to E stim at e ................................................................................. 6-5

En ter ing Molecula r St ru ctur e ....................................................................................... 6-7

En ter ing P ropert y Da ta ............................................................................................... 6-10


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Building and Running a Process Model vVersion 10.1-0

Running a Property Constant Estimation (PCES)......................................................6-14

Exa min ing Pr operty Consta nt Est ima tion Result s .....................................................6-14

Crea ting a Pr operty Ba ckup File .................................................................................6-16

Exitin g Aspen Plus .......................................................................................................6-16

7 An aly zin g Pro pe rtie s

Sta rt ing Aspen Plus........................................................................................................7-2

En ter ing Componen ts an d P ropert ies............................................................................7-2

Gener at ing a Txy Diagr am ............................................................................................7-5

A Connect i ng to the Aspen P lus S imul ati on E ngine


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vi Building and Running a Process ModelVersion 10.1-0


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Building a nd Ru nn ing a Process ModelVersion 10.1-0

vii

About Getting S tarted

Building and Running a

Process ModelAspen P lus ma kes it easy t o build and ru n a process simulation model by

providing you with a compr ehen sive system of online pr ompts, hyper text h elp,

an d expert system guidance at every step. In ma ny cases, you will be able to

develop an Aspen Plus process simulation model without referring to printed

manuals .

If you a re n ew to Aspen Plu s, you sh ould do all of these Getting Startedsessions.

To fam iliar ize your self with Aspen Plus basics, first do the br ief ha nds-on session

in Chapter 1. Then do the six other sessions in this book to learn step-by-stephow to use th e full power an d scope of Aspen Plu s. Ea ch session r equires only 20

to 30 minu tes.

This guide ass um es only th at you h ave an inst alled copy of th e softwar e. If you

ha ve not insta lled the softwar e, please see th e appr opriat e installation guide.

Why Us e P rocess Sim ulation?

Pr ocess simu lat ion a llows you t o predict t he beh avior of a process by using basic

engineering relat ionships, such a s mass a nd ener gy balances, an d phase a nd

chemical equilibrium. Given reliable therm odynamic dat a, r ealistic opera ting

conditions, a nd r igorous equipment models, you can simulate actua l plant

behavior. Process simulation enables you to run many cases, conduct "what if"

an alyses, an d perform sensitivity stu dies and optimizat ion r un s. With simulation,

you can design bett er plan ts a nd increase pr ofitability in existing plan ts.


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Building and Ru nn ing a P rocess ModelVersion 10.1-0

viii

Pr ocess simu lat ion is u seful th roughout th e ent ire lifecycle of a p rocess, from

resear ch an d development thr ough process design to production.

What is an Aspe n P lus P rocess S imu lation

Model?

A process consist s of componen ts being mixed, separ at ed, hea ted, cooled, an d

converted by un it opera tions. These components a re t ra nsferred from u nit t o unit

through process streams.

You can translate a process into an Aspen Plus process simulation model bydoing the following steps:

1. Define t he process flowsheet configur at ion. To do this s tep, you:

Define th e un it operations in th e process

Define th e process str eams tha t flow between th ese unit operat ions

Select unit operation models from the Aspen Plus model library todescribe each unit operation

2. Specify the chem ical componen ts in th e process. You can ta ke t hesecomponents from the Aspen Plus data bank s, or you can define them .

3. Choose appropriate thermodynamic models from those available in AspenPlus, to represent the physical properties of the components a nd m ixtu res in

the process.

4. Specify the componen t flow ra tes a nd t he t her modynam ic condit ions (forexample, temper at ur e an d pressur e) of feed strea ms t o the process.

5. Specify the opera ting condit ions for t he u nit opera tions in th e flowsheet .

When you ha ve specified this inform at ion, you h ave defined a n Aspen P lus

process simulat ion m odel of your pr ocess. You can u se th e Aspen Plu s pr ocess

simu lat ion m odel to predict pr ocess beha vior.

With Aspen P lus you can in ter actively chan ge specifications, such a s flowsheetconfigura tion, opera ting condit ions, a nd feed compositions, t o run new cases a nd

an alyze alterna tives.

In a ddition to process simu lat ion, Aspen Plu s allows you t o perform a wide r an ge

of other ta sks such as estimat ing and r egressing physical properties, genera ting

cust om graphical an d tabular out put r esults, data-fitting plan t dat a to

simu lat ion m odels, costing your plan t, optimizing your pr ocess, an d int erfacing

results to spreadsheets.


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ix

Sess ions in this Book

The h an ds-on sess ions in t his book a re described in t he following table:

Follow the steps in Chapter To learn how to

1 Aspen Plus Basics Start Aspen Plus, use the Aspen Plus user interface, exit Aspen Plus

2 Building and Running a Process Simulation

Model

Build and run a typical Aspen Plus process simulation model.

3 Performing a Sensitivity Analysis Use Aspen Plus to study the sensitivity of process performance to changes

in process feeds and operating variables.

4 Meeting Process Design Specifications Use Aspen Plus to make your process model meet a design specification

by manipulating a process feed or operating variable.

5 Creating a Process Flow Diagram Add stream tables, graphics, and text to your graphical simulation

flowsheet.

6 Estimating Physical Properties for a Non-

Databank Component

Use Aspen Plus to enter and estimate missing physical properties required

for simulation.

7 Analyzing Properties Use Aspen Plus to generate tables and plots of physical properties,

computed over a range of values.

For More Informa tion

Online Help Aspen P lus ha s a complete system of online help an d

context-sensitive prompts. The help system contains both context-sensitive help

an d r eference inform at ion. F or more inform at ion about u sing Aspen P lus help, see

theAspen Plus U ser Gu id e, Chapter 3.

Asp en P lu s Get t ing S t a r t ed Bu ild ing a n d R un n in g a Pr ocess Mod el This

tutorial includes several hands-on sessions to familiarize you with Aspen Plus.

The guide ta kes you step-by-step t o lear n t he full power a nd scope of Aspen Plus .

Asp en P lu s Get t in g S t a r ted Mod el in g Pr ocesses w i t h Elect r olytes This

tutorial includes several hands-on sessions to familiarize you with simulating

electrolyte systems with Aspen Plus.

Asp en P lus Get t in g S t a r t ed Mod el in g Pet r oleu m Pr ocesses This tutorial

includes several hands-on sessions to familiarize you with simulating petroleum

processes with Aspen Plus.


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Asp en P lu s Get t in g S t a r t ed Cu st om iz ing Un i t Op er a t ion Mod els This

tutorial includes several hands-on sessions to familiarize you with the

customizat ion of un it operat ion m odels with Aspen P lus.

Asp en P lu s User Gu id e The three-volume Aspen Plus User Gu id e provides

step-by-step pr ocedur es for developing an d usin g an Aspen P lus pr ocess

simu lat ion m odel. The guide is task -orien ted t o help you a ccomplish t he

engineer ing work you n eed to do, using th e powerful capa bilities of Aspen Plu s.

Asp en P lus r efe r ence m a n u a l ser ies Aspen P lus reference manu als pr ovide

detailed technical reference information. These manuals include background

informa tion a bout the un it opera tion m odels and t he ph ysical properties meth ods

an d models available in Aspen Plus, ta bles of Aspen Plus da taba nk pa ra meters,

group contribution method functional groups, and a wide range of other reference

inform at ion. The set comprises:

Un it Operation Models

Physical Property Methods an d Models Physical Property Data

User Models

System Management

System Administration

S um m ary File Toolkit

Asp en P lus a p p l ica t ion exa m p les A suite of sam ple online Aspen P lus

simu lations illust ra ting specific processes is delivered with Aspen Plus.

Asp en P lu s In st a l la t ion Gu id es These guides pr ovide inst ru ctions on

platform and network installation of Aspen Plus. The set comprises:

Aspen Plus Instal lation Gu id e for Windows Aspen Plus Instal lation Gu id e for OpenVMS

Aspen Plus Instal lation Gu id e for UNIX

The Aspen Plus man ua ls are delivered in Adobe port able document form at (PDF)

on t he Aspen Plus Documen ta tion CD.

Te ch nic al Sup port

World Wide Web For a dditiona l informa tion about AspenTech products an dservices, check th e AspenTech World Wide Web home pa ge on t he In ter net at :

http:/ /www.aspentech.com/


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Technica l resources To obtain in-depth technical support information on the

Inter net, visit t he Technical Support homepage. Register a t:

http://www.aspentech.com/ts/

Approximat ely thr ee days a fter r egistering, you will receive a confirma tion e-mailan d you will th en be able to access th is informa tion.

The m ost current Hotline cont act informa tion is listed. Oth er informa tion

includes:

Fr equently asked questions

Pr oduct tr aining cour ses

Techn ical t ips

Asp enTech Hot l in e If you need help from an AspenTech Customer Support

engineer , cont act our Hotline for an y of th e following locations:

If you are located in: Phone Number Fax Number E-Mail Address

North America & the

Caribbean

+1-617/949-1021

+1-888/996-7001

(toll free)

+1-617/949-1724 [email protected]

South America

(Argentina office)

(Brazil office)

+54-11/4393-5308

+55-11/5506-0756

+54-11/4394-8621

+55-11/5506-0567

[email protected]

[email protected]

Europe, Gulf Region, & Africa

(Brussels office)

(UK office)

+32-2/724-0100

+44-1223/312220

+32-2/705-4034

+44-1223/366980

[email protected]

Japan +81-3/3262-1743 +81-3/3262-1744 [email protected]

Asia & Australia

(Hong Kong office)

(Korea office)

+85-2/2838-6077

+82-2/761-5800

+85-2/2833-5642

+82-2/761-5803

[email protected]

y y y y


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Building and Running a Process Model 1-Version 10.1-0

Chapter 1

1 Aspen Plus Basics

The best wa y to learn basic Aspen P lus concepts is by using Aspen P lus. This

session leads you through an example Aspen Plus simulation to explain how to

open a file, enter da ta , run a simulation, an d exam ine results

Allow about 20 minu tes for t his session.


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1-2 Building and Running a Process ModelVersion 10.1-0

Aspen Plus

Basics

Starting Aspen P lus

To sta rt Aspen Plus:

From your Windows desktop, click Start and then select Programs.

Click AspenTech, select Aspen Plus 10.1-0, and click Aspen Plus User Interface.

The Aspen Plus Startup dialog box appears. You can use this dialog box to open anexisting simulation or to create a new simulation using a template or a blanksimulation.

Select the Blank Simulation option and click OK to start the new Aspen Plus

simulation.

Note If the Connect to Engine dialog box appea rs, see Appendix A.

Aspen Plus starts a new simulation with the default name, Simulation 1.

Ti p You can creat e a sh ortcut icon for your Windows deskt op tha t youdouble-click t o star t Aspen P lus. To crea te t his icon, u se Windows

Explorer to na vigat e to th e xeq folder of your Aspen P lus User

Inter face insta llat ion. Next, select t he a pwn.exe progra m a nd

dra g it ont o your Windows desktop.

The Aspe n P lus Main Wind ow

The Aspen Plus ma in window (shown in F igur e 1.1) is displayed when you sta rt

Aspen Plus . In th e work spa ce of th is window you crea te a nd displa y your

simulation flowsheet. The workspace rema ins blank unt il you en ter problem

specifications.

Aspen Plus displays context-dependent definitions and information in the prompt

ar ea of the ma in window. Whenever you n eed informa tion a bout th e curren tly

highlighted field or item, refer to th e prompt for guida nce.


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Chapter 1

Figure 1.1 Aspen Plus Main Window

Open ing a Fi le

You can open a file for a n Aspen P lus simu lat ion by either : Double-clicking the file from Windows Explorer

Selecting th e Open comma nd from the File menu in Aspen P lus

In t his section you will use th e Open comma nd on t he F ile menu to open a

partially completed Aspen Plus simulation stored in a backup file.

To display the File menu, click File on the menu bar.

Menu bar

Prompt area

Flowsheet

work space

Model Library

Toolbar

Status indicator

Scroll bars

Next buttonHelp button

Select Mode

button


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Aspen Plus

Basics

Aspen Plus displays the File menu:

From the File menu select Open.

The Open dialog box appears. Your default working directory is displayed in the LookIn box. You can navigate to the folder containing a file by using the Look In box or the

Look In Favorites button .

Click the Look in Favorites button.


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Chapter 1

A list of folders is displayed in the Open dialog box:

By defau lt, th e Fa vorites list cont ain s five folders t ha t a re pr ovided with Aspen

Plus. The files in these folders are designed to assist you in creating suitable

simulation models in Aspen Plus.

Ti p You can add folders t o th e Fa vorit es list by na vigat ing to the

app ropria te folder an d clicking th e Add to Fa vorit es but ton.

Double-click the Examples folder.

From the files list, select flash.bkp and click Open.

Click Yes when Aspen Plus prompts "Do you want to close current run before openingnew run?"

Click No when Aspen Plus prompts "Save changes to Simulation 1?"

While Aspen Plus opens the simulation model, the mouse pointer shows the busy

symbol, to indicate that Aspen Plus is finishing an operation. When the operation

is complete, the mouse pointer r etur ns t o the Select a rr ow sha pe.


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Aspen Plus

Basics

Se lecting Flow sh ee t Objec ts

In the main window workspace, Aspen Plus displays the graphical flowsheet for

th e opened Flash simu lation:

The graphical simulation flowsheet shows the feeds, products, unit operation

blocks, and process strea ms. The Flash simulation has one feed str eam (strea m

1), two product str eam s (strea ms 2 a nd 3), and one un it operat ion block (B1).

In t his section, you will select the feed str eam (strea m 1) on t he simu lat ion

flowsheet an d ent er specificat ions.


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Chapter 1

To select stream 1, place the mouse pointer over stream 1 in the graphical simulationflowsheet and click.

Stream 1 is selected and highlighted, as shown in the following figure:

Using a Sh ortcu t Men u

A shortcut men u of commands is available for t he flowsheet objects. To display the

shortcut m enu for st ream 1:

Place the mouse pointer over stream 1 and click with the right mouse button.


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Aspen Plus

Basics

The stream shortcut menu appears, listing the commands that you can execute forstream 1:

Use the Up and Down arrow keys to highlight the commands in the shortcut menu.The prompts at the bottom of the main window change as you highlight each

command.

Open ing Inpu t Forms

To open t he in put form s for a str eam , you can do any of th e following:

Select St reams from t he Data menu.

Click th e Str eams butt on on th e main window toolbar.

Select Inpu t on the shortcut men u for th e strea m.

To open the input forms for stream 1, select Input on the shortcut menu.


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Chapter 1

Ti p Alter na tively, to open a str eam or block input form quickly,double-click t he object from t he gr aph ical sim ula tion flowsheet in

the Process Flowsheet window.

The input forms for stream 1 (Material) appear in a Data Browser window, which isdisplayed on top of the Aspen Plus main window:

The Data Browser is a sheet a nd form viewer with a hierar chical menu tr ee view

(on t he left side of th e window) of th e available simu lat ion inpu t, resu lts, an d

objects that have been defined.

Using Help

When you view a form or a d ialog box, you can get cont ext-sensitive help in an y of

the following ways:

Click the box you want inform at ion on an d the Help butt on on the ma inwindow toolbar

Fr om H elp on the ma in window menu bar, select Wha ts This? from t he H elpmenu

Pr ess the H elp key (F1)

Click the Help button on the main window toolbar, then click the Specifications tabin the Data Browser.

Data Browser

menu tree


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Aspen Plus

Basics

Aspen Plus displays a Help window that explains how to use the current sheet, theStream Input Specifications Sheet:

In Help, green underlined words identify topics with additional or related help.

In th is example there is a link t o help on th e Strea m Inpu t Form a t th e end of

th e Help topic.

Scroll to the end of this Help topic and click the underlined text Input Form Help.

Help on this topic appears.

When you finish reading the help, close the Help window by clicking the Close button

on the upper right corner of the Help window.

You can a lso get help on any topic at an y time by using the H elp menu . For

example:

Click Help on the main window menu bar.

Use the arrow keys to move through the menu, and read the prompts at the bottom ofthe screen to see a description of each item .

To learn more about the Aspen Plus online help system, select Help Topics.


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Building and Running a Process Model 1-1Version 10.1-0

Chapter 1

From the Contents tab, double-click Using Aspen Plus Help and select a help topic todisplay.

When you are finished, close the Help window by clicking the Close button.

Entering Data on a Form

You u se th e Dat a Browser t o enter da ta on form s. In t his section, you will enter

missing tempera tur e, pressure, and component flow data for str eam 1.

To move from box to box on a form , use t he Ta b key or th e mouse.

Click the open Data Browser window to make it active. This returns you to the StreamsInput Specifications sheet.

Ti p Alternatively, you can select streams 1 (Material) - Data Browserfrom the Window menu in t he ma in window to make th e Data

Browser win dow active.

Enter the following specifications:

Temperature 180F

Pressure 20 psi

Methanol component flow 50 lbmol/hr

Water component flow 50 lbmol/hr

Since the default units are appropriate for this simulation, you will need to enter onlythe values.

Note If you m ake a m istake while typing, use th e Backspace key toerase th e previous char acters.


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Aspen Plus

Basics

The complet ed Str eam s Inpu t Specificat ions sh eet is shown in t he following

figure:

When you enter values in boxes or change default options on Input forms, the

specificat ions you ent er a nd t he defau lts you m odify ar e shown in black text, an d

a check ma rk will appear next to th e sheet name. On th e Specificat ions sheet,

th e tem perat ur e, pressur e, an d component flow specificat ions ar e black,

indicat ing user inpu t.

Expert Guidan cethe Next F un ction

The Aspen Plus expert system, known as t he Next fun ction, guides you t hr ough a ll

th e steps for ent erin g specificat ions for your simu lat ion m odel. The Next function:

Guides you t hr ough t he r equired and optiona l input for a simulation bydisplaying the appr opriat e forms

Displays messa ges informing you wh at you n eed to do next Ensures that you do not enter incomplete or inconsistent specifications even

when you chan ge options an d specifications you h ave alr eady ent ered

To use the Next function to complete the simulation model, click the Next buttonon the Data Browser window toolbar. (When the Data Browser window is not open,you can also click the Next button on the main window toolbar.)


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Chapter 1

Aspen Plus displays the next sheet on which input data is required for the simulationmodel, the Flash2 Input Specifications sheet for Block B1:

The input data for Block B1 on the Specifications tab is incomplete as indicated by the

symbol on the Specifications tab.

Click the Next button again.

Aspen Plus displays a Completion Status window that indicates additional data are

required:


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Aspen Plus

Basics

Close the Completion Status window.

Move to the first flash specification box and click the Down arrow to display the list offlash specification types.

Select Heat Duty from the list.

In the Heat Duty value box , enter 0. Press Enter.

To specify the flash conditions of 1 atmosphere, move the pointer to the Pressurevalue box, and type 1. Press Enter.

To change the input units from psi to atm, move to the Pressure Units box, whichcurrently displays units of psi.

Click the arrow on the pressure units box to display the available options.

The units list for pressure appears:


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Select atm from the list.

The input data on the Specifications tab is now complete, as indicated by the checkmark on the Specifications tab:

The inpu t for Block B1 is complete as indicat ed by the check mar k on th e B1

folder in t he m enu tr ee view on t he left side of th e Dat a Br owser window.

The input specifications for the simulation are complete as indicated by the

message in the sta tu s bar a t th e bottom of th e main window.

Close the Data Browser window by clicking the Close button .


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Runn ing the Simulat ion

With the input specifications for this simulation model complete, the simulation is

rea dy to be ru n. You can ru n t he simu lat ion in a ny of th e following ways:

Select Run from the Run menu in the m ain window menu ba r

Click th e Sta rt butt on on th e Simulation Run toolbar in the main windowtoolbar

Click the Run Contr ol Pa nel butt on to open the Contr ol Pa nel an d then

click th e Sta rt butt on on th e Contr ol Pa nel toolbar

Click Run on the menu bar.

Aspen Plus displays the Run menu:

Select Run.


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While Aspen Plus performs calculations for the simulation, the mouse pointer has

a st op sign sh ape. The block being execut ed is also highlighted in th e simula tion

flowsheet in th e Pr ocess Flowsheet window. When t he calculations ar e complet e,

the mouse pointer retur ns to the Select a rrow shape. In th e statu s bar a t t he

bottom of the main window, the prompt message "Simulation run completed"appear s on t he left a nd on th e right, the st at us m essage "Results Available"

appear s in blue.

Note If the calculations ar e completed with err ors or wa rn ings, thesta tus message indicat es "Results Available with Er rors" and

"Result s Available with War nings," respectively.

Examining Stream and Block Resu lts

In th is section you will view th e resu lts for the flash overhead vapor st rea m

(stream 2) and t he su mma ry r esults for t he F lash block (Block B1).

To display the flash overhead vapor (stream 2) results, click stream 2 in the graphicalflowsheet to select the stream.

With stream 2 selected, right-click on the stream to display the shortcut menu for thestream.

Select Results from the menu.


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Aspen Plus displays the thermodynamic state and composition flows of the vaporstream, stream 2, on the Streams 2 (Material) Results Sheet in a Data Browserwindow:

Use the vertical scrollbar to the right of the results to scroll down the stream results.

To display the results for the Flash Block B1, double-click Blocks on the Data Browsermenu tree and then double-click B1.


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Aspen Plus displays the results forms for Block B1 in a Data Browser window. TheBlock B1 (Flash2) Results Summary sheet displays the overall results for the block.You can see the calculated flash outlet temperature and overall vapor fraction:

Click the Next Form button on the toolbar of the Data Browser window to browsethrough the results.

Close the Data Browser window by clicking .

Modifying an d Reru nn ing You r Mode l

To simulate changing the composition of the feed stream to 60 lbmol/hr methanol

an d 40 lbmol/hr wat er:

Click stream 1 in the graphical simulation flowsheet to select it.

Right-click to display the stream shortcut menu.

Select Input from the menu.


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The input form for stream 1 appears.

Move to the Value boxes in the Composition group box and enter a component flow of60 for METHANOL and 40 for WATER.

Close the Data Browser window.

To run the simulation, select Run from the Run menu.

When the run is completed, select and display results for the outlet streams and theflash block to examine the new process results. (See Examining Stream and BlockResults, this chapter, to review how to do this.)

Exiting Aspe n P lus

To exit Aspen Plus :

Click File on the main window menu bar to display the File menu.

Select Exit.

Aspen Plus displays a dialog box asking if you want to save your simulation.

Select No to exit without saving the simulation.

Congr at ula tions! You ha ve successfully completed an Aspen Plus simula tion.

y y y y


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2 Building and Running a

Process Simulation Model

In th is session you will crea te a n Aspen Plus pr ocess model for a

methylcyclohexane (MCH) recovery column.

This session is divided int o thr ee sections:

Building th e Pr ocess Model

Adding Dat a t o th e Pr ocess Model

Runn ing the Simulation

Allow about 50 min ut es to complete th e ent ire session.


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Building the P rocess Model

In t his section, you will build th e process model by performing th ese ta sks:

Define the problem to be simulated

Start Aspen Plus

Creat e a new simulation

Define the flowsheet using the graphical interface

De fining the P roblem : Meth ylcyclohex ane

Reco very Column

The pr ocess flow diagram , opera ting condit ions, and pr oblem definit ion a re sh own

in F igur e 2.1.

Figure 2.1 Problem Definition: MCH Recovery Column

MCH a nd t oluene form a close-boiling system t ha t is difficult to separ at e by

simple binar y distillat ion. In t he r ecovery column in Figur e 2.1, phen ol is used to

extra ct toluene, allowing rela tively pure m eth ylcyclohexan e to be recovered in

th e overhead.


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In t his session, you will evalu at e th e perform an ce of an existing column for

recovering MCH from a feed str eam with a lower concentra tion t ha n t he original

design condit ions. You can increas e th e phen ol solvent r at e to improve MCH

recovery. However, you n eed to simulat e th e column to deter mine t he pr oduct

pur ity, colum n flow, an d composition p rofiles, an d th e conden ser a nd r eboilerdut ies, for a given solvent ra te.

Starting Aspe n P lus


Start Aspen Plus from the Windows Start menu or by double-clicking the Aspen Plusicon on your desktop.

For more deta iled inform at ion, see Star ting Aspen P lus in Chapt er 1.

The Aspen Plus St ar tu p dialog box appear s.

Creat ing a New Simulat ion

Aspen Plus provides built-in templates for applications such as chemicals,

petroleum, electrolytes, specialty chemicals, pharmaceuticals, and metallurgy.

On the Aspen Plus Startup dialog box, select the Template option. Click OK tocontinue.

The New dialog box appears.

Use t he New dialog box to specify th e temp lat e an d Run Type for t he n ew

simu lat ion. Use t he Ru n Type option to select t he t ype of calculat ions you wan t t o

perform. For example, you can perform flowsheet simulation, data regression,

an d property estima tion calculat ions.

On the New dialog box, click any item in the list of templates.

A brief description of the selected template appears in the Preview box on the rightside of the dialog box.

Select the General with English Units template for this session.


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The default Run Type, Flowsheet, is appropriate for this session.

Click OK to start the new Aspen Plus simulation.

Note If the Conn ect to En gine dialog box appea rs, see Append ix A.

Aspen Plus starts a new simulation with the default name, Simulation 1.

The Aspe n P lus Main Wind ow

The Aspen Plus ma in window is displayed when you sta rt Aspen P lus. Becau se you

ha ve not ent ered a ny pr oblem specificat ions yet, the workspa ce is blank :

For more information about the main window, refer to the section, The Aspen

Plus Ma in Window, in Chapt er 1.


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Click the Next button on the Aspen Plus main window toolbar.

Aspen Plus displays the Flowsheet Definition dialog box telling you that the first step isto define the flowsheet in the graphics workspace:

Click OK to close the dialog box.

Defin ing the F low shee tIn th e flowsheet for t he MCH process shown in F igur e 2.1, ther e ar e two feed

str eams (MCH-toluene feed an d ph enol solvent), one u nit operat ion (an extractive

distillation column), and two product streams (distillate and bottoms).

In th is session, you will define t he pr ocess flowsheet by placing u nit operat ion

blocks in the workspace and connecting streams to the blocks.

Next button


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First you will select a unit operation model to simulate the extractive distillation

column.

From the Aspen Plus main window, click the Columns tab on the Model Library.

The list of available distillation columns is displayed. Move the mouse over any modelin the Model Library and read the description in the lower left of the window.

Move the mouse over the RadFrac block and read the prompt.

The prompt for RadFrac suggests this is the right model for this problem.

Click RadFrac, then press the Help key (F1).

The help information confirms that RadFrac is suitable for extractive distillation.

Close the Help window.

The RadF ra c model can be represent ed on th e flowsheet by a nu mber of pictorial

icons. You can select t he defau lt displayed in t he Model Libra ry or select a

different icon from t he icon list:

To choose a different icon for RadFrac, click the down arrow to the right of RadFrac inthe Model Library.

The available icons for RadFrac are displayed:


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Move the mouse pointer over the displayed icons to view the label for each icon.

In this session, you will use the icon labeled FRACT1 for the RadFrac block.

Select the RadFrac icon that you want to place in your process flowsheet.

Note The icon you select becomes t he d efau lt icon for th e model, unt ilyou select a different icon.

Click the icon and drag it to the Process Flowsheet window.

The mouse pointer is in the shape of a box with an arrow, which indicates that onlyone block will be placed.

In the Process Flowsheet window, release the mouse button where you want to placethe block. The icon that you selected appears on the flowsheet.

Ti p Alter na tively, you can click t he icon in t he Model Libra ry a ndth en click the a rea in th e process flowsheet window wher e you

wan t t o place th e block. This meth od allows you t o place mu ltiple

blocks by clicking different locations in the process flowsheet

window.

Aspen Plus automatically assigns a block ID, B1, to your RadFrac block.


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Ti p To stop th e au toma tic nam ing of blocks, select Options from t heTools menu, click the Flowsheet tab and deselect the

Aut oma tically Assign Block Na me option.

The inserted RadFrac block is shown below:

Next, place th e str eam s for t he Ra dFr ac column by doing th e following:

Click the Material Stream icon on the left side of the Model Library.

Ti p To select a Heat or Work st ream , click t he down ar row next to the

Mater ial Stream icon a nd choose Heat or Work st ream .

Move the cursor to the Process Flowsheet window.

For each block in the Process Flowsheet window, all ports that are compatible with thestream type you selected are highlighted.


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Ports th at m ust h ave at least one stream conn ected ar e shown in red. Optiona l

ports a re sh own in blu e. If you position t he m ouse point er over a port for a few

seconds, th e ar row is highlighted a nd a description of th e port appear s.

Four required ports, shown with red arrows, appear on the RadFrac block B1. Movethe mouse over the red arrows; the port labels indicate the types of port that arerequired to be connected to at least one stream.

To connect the feed streams:

Point to the RadFrac Feed (Required; one or more) port on the RadFrac icon in the

process flowsheet window. Click once to select it.

Move the mouse pointer to a blank part of the process flowsheet window where youwant the feed stream to originate in your graphical flowsheet and click once.

A feed stream connecting the selected inlet port is created. Aspen Plus automaticallyassigns the ID 1 to this stream.


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Similarly, connect a second feed stream to the same feed port on the RadFrac icon.

To connect the overhead liquid distillate product stream:

Move the mouse pointer through the ports until the port labeled Liquid Distillate(Required if Distillate Vapor Fraction < 1(Setup Condenser sheet)) appears. Click theleft mouse button once to select it.

Move the mouse pointer to a blank part of the process flowsheet window where youwant the product stream to terminate in your graphical flowsheet, and click.

Product stream 3 is created, connected to the selected outlet port.

To conn ect th e bottoms pr oduct str eam:

Move the mouse pointer through the ports until the port labeled Bottoms (Required)appears. Click once to select it.

Move the mouse pointer to a blank part of the Process Flowsheet window and clickonce to create Stream 4.

When you have finished placing streams, click the Select Mode button in theupper left corner of the Model Library.

Ti p To cancel conn ecting th e str eam at an y time, press ESC.

To delete a strea m, select t he st rea m in the graph ical flowsheetan d press th e Delete key.

Your graphical simulation flowsheet is now complete. The status indicator in the

bottom right of the main window says "Required Input Incomplete" indicating

th at fur th er input specificat ions a re r equired for t he simulat ion.


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Adding Da ta to the P rocess Mode l

Now tha t you ha ve defined your flowsheet gra phically, use t he Da ta Browser input

forms t o enter th e rema ining required inform at ion for t his run .

You can rely on t he Aspen Plus Next function t o display th e requ ired inpu t form sAs an altern at ive, you can display th e input forms by:

Selecting the a ppropriate forms from the Dat a m enu

Clicking the appr opriat e butt on on th e Data Browser toolbarin the m ain window

Selecting an object in t he gra phical flowsheet a nd clicking Input on t heshortcut menu


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Double-clicking an object in the graphical flowsheet

(For more information on opening Input forms, see Chapter 1.)

For t his section, you will use t he N ext function.

Click the Next button in the main window toolbar.

Aspen Plus d isplays a d ialog box telling you t ha t your flowsheet is complete an d

th at you a re n ow ready t o provide rema ining specificat ions t hr ough t he inpu t

forms.

Click OK to display the first required input form.

Aspen Plus displays a Da ta Browser window conta ining th e Setu p Specificat ions

form s. The Data Browser window title bar cont ains t he form na me.

In th e following sections, you will enter inpu t specifications for your model.


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Spe cifying Title , Stream P roperties , an d

Units

The Set up Specifications form displays some of the defau lts Aspen Plu s uses for t he

oth er simu lation forms . (Global defau lts a ppear on all subsequent forms, but you

can override t hem .) You will use th e Global sh eet t o give your simu lat ion a title.

You can also review the other global options t ha t wer e set wh en you selected

Genera l with En glish Units as t he Applicat ion Type.

Use either the mouse, or the Tab key to move from box to box on the form and readthe prompts at the bottom of the main window.

When you are finished reading about the boxes on this form, click the Title box.

In the Title box, enter Methylcyclohexane Recovery Process and then press Enter.

The values for the r ema ining boxes on t his sheet esta blish global default s for

your simulation input. F or this session you will use En glish un its an d th e oth er

default s, so you do not n eed to specify an ythin g else on t his sh eet.

In the menu tree of the Data Browser window, click the Report Options form in theSetup folder to review the report options specified in the selected Template.

Aspen Plus a lways calculat es tem perat ur e, pressur e, vapor fra ction, m olecular

weight a nd t ota l flow, entha lpy, entr opy, and density for t he simulat ion st ream s.

Because you selected t he Gener al with E nglish Un its Application Type when you

creat ed th is ru n, Aspen Plus will also calcula te componen t m ole flow by default.

Click the Stream tab to view the Stream sheet.

On t he St ream sheet, you can specify which additiona l properties you want

Aspen Plus to calculat e an d report . The componen t flow an d fraction ba ses an d

additiona l propert ies requested on th is form will be included in th e Str eam-

Summa ry reports.

To specify that you would like to have Aspen Plus calculate mole fractions, click theFraction Basis Mole checkbox.

You can also request th at Aspen Plus calculate an d report a dditiona l strea m

propert ies. A nu mber of sets of additional pr operties a re bu ilt in to Aspen Plus for

each applicat ion t ype, as P roperty Sets.


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Click the Property Sets button.

You can use the Property Sets dialog box to enter additional property sets for yourcalculations.

The Available Property Set, TXPORT, conta ins tr an sport properties an d density.

To specify that you want Aspen Plus to calculate transport properties, select theTXPORT Property Set in the Available Property Sets list.

Click the right arrow button to move TXPORT Property Set from the Availablelist it to the Selected list.

Click Close to close the Property Sets dialog box.

Click the Next button on the Data Browser window toolbar, to move to the nextrequired input form.

The Components Specifications form appears.

Entering Compon en ts

You use t he Componen ts Specifications Selection sh eet t o select th e chemical

components pr esent in t he simulat ion.

The components for the process in this example are toluene, phenol, and

methylcyclohexane. For each component, you must enter a unique component ID.

In the first Component ID box, type TOLUENE and press Enter.

(If you m ake a mistak e while typing, use th e Backspace key to erase. )

Because Aspen Plus recognizes the componen t n am e Toluene a s an Aspen Plus

databank component, Aspen Plus fills in the Type, Component Name, andFormula boxes automatically.

Click the next blank Component ID box, below TOLUENE. Type PHENOL and pressEnter.

Aspen Plus again fills in the Type, Component Name, and Formula boxes.


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For m eth ylcyclohexan e, use th e abbreviat ion MCH for the component ID:

Move to the next blank Component ID box for MCH. Type MCH and press Enter.

Because you have used an abbreviation, MCH, to represent methylcyclohexane,you mu st also enter a databank formu la or dat abank name t o retrieve the

appr opriat e component da ta from the Aspen Plus dat aban k.

Click the blank Component Name box. Type the partial name METHYLCYC andpress Enter.

The F ind dialog box appea rs, listing all the component s in th e Aspen Plus

dat aban k th at h ave a na me conta ining the letter s you typed, METHYLCYC:

Use t he F ind dia log box to choose th e componen t you n eed.

Ti p To view the complete componen t n am e, click a nd slide th e rightedge of th e componen t n am e colum n label to th e right.


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Using the mouse, or the Up and Down arrow keys, look through the list until you findMETHYLCYCLOHE... The corresponding Formula, Databank, Molecular Weight,Boiling Point, CAS Number, and Component Class are displayed in the searched list.

Select the component METHYLCYCLOHEXANE from the list and click Add to add it tothe component list.

Note You can cont inue add ing componen ts from th is dialog box or closeit .

Ti p If you need t o search for componen ts ba sed on molecula r weightra nge, boiling point ra nge, or CAS num bers, you sh ould us e th e

Advan ced sheet in t he F ind dialog box.

Click Close to return to the Components Specifications Selection sheet.

You h ave now specified th e th ree componen ts r equired for th is process

simu lation m odel, Toluene, P hen ol, an d Meth ylcyclohexa ne.

Click the Next button on the Data Browser window toolbar.

The Aspen Plus expert system displays th e next r equired sheet, the P roperties

Specificat ions Global sheet .

Select ing The rmodyn amic Methods

Use th e Pr operties Specificat ions Global sheet to select t he t herm odynam ic

meth ods used to calculat e properties such a s K-values, entha lpy, an d density.

Pr operty met hods in Aspen P lus ar e ar ra nged according to Process Types an d in

logical gr oupings called Bas e Met hod.

For t his simu lat ion, use t he UN IFAC activity coefficient m odel to estima te

liquid-pha se nonideality.

To find the appropriate type of base method for this simulation:

Click the arrow to the right of the Base Method box to display the availablethermodynamic property methods in Aspen Plus.


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You can get basic information about a base method by using the mouse or the

ar row keys to move to th e base meth od an d rea ding the prompt. For more

informa tion a bout a ba se meth od, you can move to the ba se meth od na me a nd

use Help.

To select the UNIFAC property method:

Move the highlight down the list to the UNIFAC property method. The information inthe prompt indicates this is the appropriate property method for this simulation.

Select UNIFAC by clicking it.


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The Requir ed Pr operties Inpu t Complete dialog box appea rs. This dialog box

allows you to select additional input forms for physical property parameters and

estimation.

However, th e propert y specificat ions for th is problem ar e complete, so you can

cont inue to the next r equired input.

Click OK to close the dialog box.

Entering Stream Data

The Str eam In put Specificat ions sh eet for St ream 1 appear s, as indicat ed in the

Data Browser window title bar . Str eam 1 will be the MCH-toluene feed stream .

Enter the following state variable and component flow specifications for the MCH-toluene feed stream:

Temperature 220 FPressure 20 psiToluene flow value 200 lbmol/hrMCH flow value 200 lbmol/hr


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Because the default units are correct for this simulation, you will need to only enter thevalues. (Refer to Entering Data on Forms in Chapter 1 for more information.)

You h ave now finished entering dat a for St ream 1, as indicat ed by the Input

Complete message in th e Data Browser st at us bar , at t he lower left of th e

window.

Click Next on the Data Browser window toolbar to guide you to the next form.

The Str eam Specificat ions form for St rea m 2 a ppears, as indicat ed in th e DataBrowser window title bar . Strea m 2 will be th e phenol feed strea m.

Enter the following stream specifications for the phenol solvent stream:

Temperature 220 FPressure 20 PSIPhenol flow value 1200 lbmol/hr

The feed str eam specifications for t he m odel ar e now complete.

Click Next on the Data Browser window toolbar.

The RadFrac Setup form for block B1 appears.


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Entering Un it Operation Block Da ta

On th e RadFr ac Setup Configur at ion sh eet, you ent er t he nu mber of theoretical

sta ges, th e valid pha ses in th e column, t he distillat e vapor fra ction, an d other

operat ing specificat ions for th e column .

Use the TAB key to move through the boxes on the form, and read the descriptiveprompts for each box.

The red Incomplete sta tus indicat or next to th e Configura tion ta b tells you

th at the sh eet is not yet complete and you must en ter some additiona l

specifications.

To learn what specifications this sheet requires, click the Next button on the DataBrowser window title bar.

The Aspen Plus expert system displays a Completion St at us window, stat ing tha t

you n eed to enter Nu mber of sta ges, Conden ser t ype, and t wo out of a list of

specificat ions, in order t o complete th is sheet :


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Close the Completion Status window.

Now enter the operating specifications for the column:

Number of stages 22

Click the Condenser list box and select Total

Distillate Rate 200 lbmol/hr

Reflux ratio 8

The d efau lt of Vapor-Liquid for Valid ph ases is corr ect for th is problem because

we expect only a vapor pha se an d one liquid pha se.

The blue check mar k next t o the Configura tion t ab indicat es the sh eet is

complete.


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The RadFr ac column m odel requires more tha n one sheet to enter t he necessary

information. The expert system displays the Streams sheet, on which you specify

feed and pr oduct st age locations.

In t he RadF ra c model, sta ge 1 is th e top stage (condenser ) and sta ge N (where N

is the n um ber of sta ges) is the bottom st age (reboiler). For th e process th at you

ar e simulat ing (shown in F igur e 2.1), the MCH-toluene feed (str eam 1) enter s

above sta ge 14, and th e phenol solvent st ream (str eam 2) enter s above sta ge 7.

For stream 1, enter a feed stage location of 14.

For stream 2, enter a feed stage location of 7 and press Enter.

The Str eams sheet is n ow complete:


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Click the Next button to view the next required input sheet.

On th e next required sheet, th e Pressu re sheet, you will enter the column

pres sur e profile. You m ay en ter a s ta ge-by-sta ge profile, or specify a top-sta ge

pressur e an d a pr essure dr op for t he r est of th e column. F or t he MCH r ecovery

column in this example, use a condenser pressure of 16 psia, and a reboiler

pressur e of 20.2 psia. In th e simulat ion, Aspen Plus will interpolat e th e pressu re

of th e intermediat e stages.

Click the arrow to the right of the View box to display a list of available views, andselect Pressure profile.

In the Stage box, enter 1 to indicate the top stage (condenser). Enter 16 psi for thepressure of this stage.

In the next Stage box enter 22 to indicate the bottom stage (reboiler). Enter 20.2 psifor the pressure and press Enter.

The P ressur e sheet is now complete.


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The Inpu t Complete message in the Dat a Browser stat us bar in the lower left of

the window, indicates that you have completed the required specifications for the

column model.

All the r equired forms for t he flowsheet ar e now complet e. You can still enter

specificat ions on optiona l inpu t forms. You can a lso go back to an y of th e requ ired

form s and m ake changes.

To see what optional input forms are available, use the scroll bar on the left side of theData Browser window to view all the folders.

The blue check mar ks on the Setu p, Components, Pr operties, Stream s, and

Blocks folders indicate that these required forms are complete.

The r ema ining inpu t folders Reactions, Convergen ce, Flowsheeting Options, an d

Model Analysis Tools are optional

For th is exam ple, ther e is no additiona l input.


The Requir ed Inpu t Complete dialog box confirms t ha t a ll requ ired specificat ions

ar e complete, and pr ompts you t o run t he simulat ion:


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Runn ing the Simu lat ion

To ru n th e simulation:

Click OK on the Required Input Complete dialog box.

Aspen Plus displays the Control Panel.

The Control Pan el allows you to monitor an d inter act with the Aspen Plus

simu lat ion calculations. For more inform at ion on how to contr ol th e simula tion

th rough the Contr ol Pan el, you can either see the Aspen PlusUser Guide,

Volum e 1, Chapt er 11, or see t he t opic Control Pan el:aboutin th e on-line H elp.

The simulat ion calculat ions occur in t hr ee sequential st eps:

Pr ocessing inpu t specifications

Calculat ions begin

Generating results

As Aspen Plus executes t he simulat ion, sta tu s messages appea r in t he Control

Pa nel. When the simu lation h as completed, the message R esu lt s Available

appear s in the sta tu s bar a t th e bottom of the ma in window.


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Examining Sim ulation Res ults

When theResu lts A va ilab le message appears in the st atu s ar ea, you can examine

th e resu lts of your flowsheet simu lation r un .

If the Control Panel window obscures your view of the graphical simulation flowsheet,

close the window by clicking .

Examining Block Res ults

To display t he r esult s for block B1:

Click Block B1 in the simulation flowsheet.

The Block icon is surrounded by square bullets, indicating it is selected.

Continue to point to the column and click (or press and hold) the right mouse button.

The Block menu appear s, showing all the comma nds t ha t a pply to a block.


The RadFrac ResultsSummary form appears in a Data Browser window.

For th is run , results a re r eport ed on several form s, as indicat ed by the check

mar k next to the form names in the menu tree. The Summa ry sheet reports a

summ ar y of column results, such a s condenser an d reboiler dut ies:


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To examine the RadFrac profile results, click the Next Form button on the DataBrowser window toolbar.

-or-

Click the Profiles form in the menu tree on the left side of the Data Browser window.

The displayed Profiles TPFQ sheet r eport s tempera tu re, pressur e, enth alpies,

an d flow profiles for th e RadF ra c colum n:


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Use the scroll bars at the bottom of the window and to the right to view up and down,and left and right, through the displayed profiles. You can also resize the window toexpand the view.

By default, the Summary view of the TPFQ profile results is shown. You can use theView box to select a different view of the TPFQ profile results.

Click the arrow on the right of the View box to display a list of available views, andselect Stage Flows.

You can use the Basis box to specify the flow basis for the displayed results.

Click the arrow on the right of the Basis box to display a list of available flow bases.

To display the RadFrac Composition results, click the RadFrac Profiles Compositionstab.

On th e Composition sh eet, wh en t he Liqu id View is selected, liquid composition

(as mole fra ction) profiles are sh own for t he Ra dFr ac column :

Check the purity of the methylcyclohexane overhead product (about 97%) byexamining the composition at the top of the column (stage 1).


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Examining Stream Results

You can display calculat ed str eam results by selecting a str eam directly from th e

graphical simulation flowsheet.

To display th e gra phical flowsheet, first close th e Dat a Br owser win dow:

Click the command icon in the upper left corner of the Data Browser window todisplay the command menu.

Select Close to close the Data Browser window.

To display th e results for Str eam 3:

On the flowsheet, click in the rectangle that displays the stream ID 3 to select it.

Display the Stream shortcut menu by right-clicking Stream 3 while it is selected.


The Mat erial sheet is displayed, showing th e resu lts for St ream 3. In addition t o

th e ther modyna mic sta te a nd flow results for t he str eam, th e properties you

requested on th e Setup Report Options sh eet ar e also displayed.


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To display th e results for St ream s 1 an d 4 on t he sa me form as t he r esults for

Stream 3:

Move to the blank box next to 3 (in the next column).

Click the list box and select 4 from the dropdown list to display results for stream 4.

To display results for stream 1, repeat the preceding step and select 1 in the nextcolumn of the table.

The Mat erial sheet displays results for St rea ms 3, 4, and 1:

Fr om th e component flow rat es report ed in the str eam r esults, you can deter mine

th at th e met hylcyclohexan e recovery overhea d is 97%.

Chan ging Inpu t Specificat ions

In t his section, you wan t t o see th e effect of increasing th e solvent flow ra te on th e

pur ity an d recovery of meth ylcyclohexane. To increase th e phen ol solvent st rea m

flow r at e from 1200 lbmol/hr to 1800 lbmol/hr :

Close the Stream Results form by clicking the in the top right corner of the DataBrowser window.


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Select Stream 2 on the graphical simulation flowsheet.

From the Stream shortcut menu, select Input to display the Stream InputSpecifications sheet.

Use the Tab key to move to the PHENOL flow value box, or click in the box.

Change the PHENOL flow rate from 1200 to 1800 lbmol/hr by entering 1800.

Rerun ning the Simulat ion

To reru n th e model with th e cha nged input :

Click the Next button on the main window toolbar.

The Required Input Complete dialog box appears telling you that you input is

complete an d asking if you wa nt to run the simu lation with the n ew

specifications.

Select OK to run the simulation.

The Control Panel appea rs a gain, and the column calculat ions a re completed

using the new phenol flow rate.

Display the block and stream results for the new conditions, as previously

described. You will observe t ha t in creasing t he solvent flow ra te from 1200 to

1800 lbmol/hr increases the MCH purity in the overhead product to 98.4% and

th e MCH recovery t o 98.4%.

To choose th e optima l condit ions, it would be h elpful t o gener at e a sensit ivity

ta ble of MCH r ecovery an d pur ity versus p hen ol flow rat e. This example is in

Chapter 3.


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Creatin g Reports

To generate a report of the simulation specifications, calculations, and results:

From the File menu in the main window, select Export.

On the Export dialog box, select Report File (*.rep) in the Save As Type box.

Type the filename mchin the File name box.

Click Save to generate the report file, mch.rep.


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You can open t his file with a text editor or you can pr int t he file. By defau lt, the

report file mch.rep is saved in your work ing directory (displayed in t he Sa ve In

box). You can select an oth er dir ectory by na vigat ing to it us ing th e Sa ve In box.

Ti p You can also exam ine th e report by selecting Report from t heView men u on t he m ain window. The Report dialog box allowsyou t o select which section of th e report you wa nt displayed in a

text editor (selecting the simulation will display the entire

report).

Exiting Aspen P lus

When you ar e finished workin g with th is model, you can exit Aspen P lus a s follows

From the File menu, select Exit.

When the dialog box appears, select YES to save the simulation.

In the Save As dialog box, enter the Run ID mch in the File name box.

Aspen Plus saves the simulation as the Aspen Plus Document file, mch.apw, in your

default working directory (displayed in the Save In box). This saved simulation will beused as the starting point for the exercises in Chapters 3 and 4.

Congra tulat ions! You ha ve just built an d r un a complete simulation model using

Aspen P lus.

y y y y


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3 Performing a Sensitivity

Analysis

One of th e benefits of using a pr ocess simu lation model is tha t you can qu ickly

stu dy the sen sitivity of process perform an ce to cha nges in pr ocess operat ing

var iables. With Aspen Plus, you can a llow simula tion input s to vary, an d can

ta bulat e th e effect on a set of result s of your choice.

In t his session, you will lear n h ow to perform sensit ivity an alysis with

Aspen P lus.

Allow about 20 minu tes for t his session.

This session assumes that you have successfully completed the

methylcyclohexane (MCH) recovery column simulation in Chapter 2, and that

you h ave sa ved the simu lat ion a s th e Aspen P lus docum ent file, mch.apw. If youha ve not creat ed the Chapt er 2 example, you can open a backup file from th e

Aspen Plus Examples folder as described in Opening an Existing Simulation, this

chapter.


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Starting Aspe n P lus


Start Aspen Plus from the Windows Start menu or by double-clicking the Aspen Plusicon on your desktop.

For more details, see Star ting Aspen Plus in Cha pter 1.

The Aspen Plus St ar tu p dialog box appear s.

Open ing an Exist ing Simu lation

If you saved t he m eth ylcyclohexane (MCH) recovery column simu lat ion crea ted in

Chapter 2:

Select the option Open an Existing Simulation on the Aspen Plus Startup dialog box.

If your saved file mch.apw is displayed in t he list box:

Select mch.apw in the list and click OK.

If your saved file mch.apw is not displa yed in t he list box:

Double-click on More Files in the list box.

In the Open dialog box that appears, use the Look In box to navigate to the directorythat contains your saved file mch.apw.

Select mch.apw in the list of files and click Open.

Note If the Conn ect to En gine dialog box appea rs, see Append ix A.

Aspen Plus displays the graphical flowsheet for the MCH column simulation.

If you did not creat e th e MCH simulat ion in Chapt er 2, you can open t he backup

file mch.bkp in t he E xamp les folder.


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From the Aspen Plus Startup dialog box, select the option Open an Existing Simulationand then click OK.

The Open dialog box appears.

Using the Look In box and the list of f iles and folders displayed, navigate to theExamples folders in the Aspen Plus user interface installation directory (e:\ProgramFiles\AspenTech\Aspen Plus 10.1-0\Favorites\Examples by default).

Double-click the Examples folder.

Select mch.bkp and click OK.

Note If the Conn ect to En gine dialog box appea rs, see Appendix A.

Aspen Plus displays the graphical flowsheet for the MCH column simulation.

Saving a S imulation unde r a New Name

Before you create a sensitivity simula tion sta rt ing from t he MCH column

simu lat ion, creat e an d save a copy of th e MCH simu lat ion file with a new file

na me, MCHSEN S. Then you can modify th is new file.

From the File menu, click Save As.

In the Save As dialog box, choose the directory where you want to save the simulation

In the Filename box, enter the new filename mchsens.

From the Save as Type list, select Aspen Plus Documents (*.apw).

Click Save to save the simulation and continue.

Aspen Plus creat es a n ew simula tion model, MCHSE NS, which is a copy of the

base case simulat ion, MCH.


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De finin g the Se nsit ivity Analysis

In t he base case MCH simulation in Chapt er 2, you simulat ed the MCH r ecovery

column performa nce at two values for t he ph enol solvent flow ra te (1200 and 1800

lbmol/hr). In the sensitivity analysis, you will want to tabulate methylcyclohexane

(MCH) distillate product purity (mole fraction), as well as condenser duty and

reboiler dut y, for severa l different flow rat es of phen ol.

Entering Sen sit ivity Spe cifications

To enter sensit ivity specificat ions, u se Sen sitivity forms, which you access from th e

Data menu:

To display the Data menu, click Data on the main window menu bar.

Drag the mouse through the Data menu and read the prompts at the bottom of thewindow for each type of form.

Select Model Analysis Tools and then select Sensitivity from the submenu.

Aspen Plus displays the Sensitivity Object Manager from which you can create newSensitivity blocks, as well as edit input, display results, or perform other operations onexisting Sensitivity blocks.

On the Sensitivity Object Manager, click New.

The Create New ID dialog box appears, displaying an automatically generatedSensitivity ID, S-1. You can accept the default ID or replace it with an ID of yourchoice.

In the Create New ID dialog box, click OK to accept the default ID and continue.


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The Sensitivity Input Define sheet for S-1 appears:

Ea ch sensitivity ana lysis genera tes a ta ble. You will define th e resu lts you want

to look a t, th e inputs you want to var y, and how Aspen Plus tabulat es the r esults.

Definin g Sa mp led Variables

On th e Inpu t Define sheet , you select t he simulat ion var iables you wa nt tosam ple for t he sensitivity an alysis a nd give each variable a u nique na me. In t his

example you will define the MCH distillate product purity, the condenser duty,

an d the r eboiler dut y as sam pled var iables.

To select t he MCH distillate pr oduct pur ity as a sam pled var iable:

Click the New button.

The Create New Variable dialog box appears.

Type XMCH in the Variable Name field and click OK to continue.

The Variable Definition dialog box appears. MCH distillate product purity is the molefraction of component MCH in the distillate product, stream 3. This sampled variablebelongs to the Streams category and is of type Mole fraction.

Under Category, click the Streams button to select the variable category.


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In the Reference frame, click the arrow to the right of the Type box to display a list offlowsheet variable types that can be accessed for streams.

Move through the list using the arrow keys, and look at the descriptive prompts.

Select the Type Mole-Frac, since the variable is a component mole fraction.

Aspen Plus displays the other fields necessary to complete the variable definition. Inthis case, the Stream list box appears.

Select stream 3, the liquid distillate stream from the dropdown list in the Stream listbox.

The Substream and Component list boxes appear. In this example, you do not need tomodify the default choice of MIXED in the Substream lis

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