aspen plus manual

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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 19811998 Aspen Technology, Inc.ALL RIGHTS RESERVED

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

ADVENT, Aspen Cust om Modeler, Aspen Dyna mics, Aspen P lus, Aspen Tech, BioProcessSimulator (BPS), Dyna PLUS, ModelMana ger, Plan telligence, th e Pla nt elligence logo,POLYMERS PLU S, PROPERTIES PLUS, SPEEDUP , and th e aspen leaf logo are either registeredtr adema rks, or tr adema rks of Aspen Techn ology, Inc., in the U nited Sta tes a nd/or other coun tr ies.

BATCHFRAC an d RATEF RAC 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 Rainbow Techn ologies, Inc.

lan License Man ager is a tr adema rk of lan Computer Group, Inc., Moun ta in View, Californ ia, USA.

Microsoft Windows, Windows NT, and Windows 95 ar e either registered tr adema rks or tr adema rks ofMicrosoft Corporation in the United States and/or other countries.

All other bran d and pr oduct nam es are tr adema rks or registered tr adema rks of their r espectivecompanies.

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

lan License Man ager 1989-1997 lan Compu ter Group, Inc.All right s reser ved

Use of Aspen Plus an d This Manu alThis ma nu al is intended a s a guide to using Aspen P lus process modeling softwar e. This documenta tion containsAspenTech proprietar y an d confident ial inform ation a nd ma y not be disclosed, used, or copied without t he pr iorconsent of AspenTech or as set forth in the applicable license agreement. Users are solely responsible for theproper use of Aspen P lus an d th e application of th e results obta ined.

Alth ough AspenTech has t ested th e software an d reviewed th e docum enta tion, the sole warr an ty for Aspen Plusma y be found in t he app licable license agreem ent bet ween AspenTech a nd t he user . ASPEN TECH MAKES NOWARRANTY OR REP RESEN TATION, EITHER EXPRESS OR IMPLIED, WITH RESP ECT TO THIS

DOCUMENTATION, ITS QUALITY, PERFORMANCE, MERCHANTABILITY, OR FITNESS FOR A

PARTICULAR PURP OSE.


3/140Aspen Plus Get t ing Star ted iiVersion 10

Contents

About Get t ing Star ted Bui ld ing and Runnin g a Process Model

Why Use Process Simulation?.....................................................................viiWhat is a n Aspen P lus Pr ocess S imu lation Model? ..................................viiiSess ions in th is Book.....................................................................................ixFor Mor e In form at ion ................................................................................... ixTechn ical Su pport .......................................................................................... x

1 Aspe n Plus Basic s

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

The Aspen P lus Ma in Wind ow ...................................................................1-2Open ing a File .............................................................................................1-3Selecting Flowshee t Objects ........................................................................1-6Usin g a S hor tcu t Menu ...............................................................................1-7Open ing In pu t F orm s..................................................................................1-8Usin g He lp ...................................................................................................1 -9En ter ing Da ta on a Form ...........................................................................1-11Expert Guidancethe Next Function.......................................................1-12Run nin g th e Sim ula tion ...........................................................................1-16Exa min ing Str eam an d Block Result s .....................................................1-17Modifying an d Reru nn ing Your Model......................................................1-19Exitin g Aspen Plus.....................................................................................1-20

2 Bui lding and Running a Process Simulat ion Model

Building t he Pr ocess M odel ........................................................................2-2Definin g th e Pr oblem: Meth ylcyclohexa ne R ecovery Column .................2-2St ar tin g Aspen Plu s ....................................................................................2-3Creat ing a New Simu lat ion ........................................................................2-3The Aspen P lus Ma in Wind ow ...................................................................2-4Defining t he Flowsh eet ...............................................................................2-5Adding Da ta to th e Pr ocess Model ...........................................................2-11Specifying Title, St rea m Pr operties, a nd Un its ......................................2-13En ter ing Compon en ts ...............................................................................2-14

Selecting Thermodynamic Methods.........................................................2-16En te rin g St rea m Da ta ..............................................................................2-18En ter ing Un it Opera tion Block Dat a .......................................................2-20Run nin g th e Sim ula tion ...........................................................................2-25Examining Simulation Results.................................................................2-26Exa min ing Block Resu lts ..........................................................................2-26Examining Stream Results.......................................................................2-29Chan ging Inpu t Specificat ions .................................................................2-30Rer un nin g th e Sim ula tion ........................................................................2 -31


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Creat ing Report s .......................................................................................2-32Exit ing Aspen Plus ....................................................................................2-33

3 Performing a Sens it ivity Analysis

St ar tin g Aspen Plu s ....................................................................................3-2Open ing an Existin g Simula tion .................................................................3-2Saving a Simu lation un der a New Na me...................................................3-3Definin g t he Sens itivity Ana lysis ................................................................3-4En ter ing Sensitivity Specificat ions ..............................................................3-4

Defining Sa m pled Var iables .................................................................3-5Defining Manipulated Variables..........................................................3-9Defining Tabu lat ed Var iables ............................................................3-11

Run nin g th e Simu lation .............................................................................3-14Displa ying Sensit ivity Ana lysis Resu lts ..................................................3-15Plottin g Sensit ivity Resu lts .......................................................................3-16Exiting Aspen Plus .....................................................................................3-17

4 Meet ing Process Des ign Speci f icat ions

Sta rt ing Aspen Plus .....................................................................................4-2Open ing an Exist ing Simu lat ion ................................................................4-2Saving a Simu lation Under a New Nam e ...................................................4-3Definin g th e Design Specificat ion................................................................4-4En ter ing Design Specificat ions ....................................................................4-4Run nin g th e Simu lation...............................................................................4-9Examin ing Design Specificat ion Result s ...................................................4-10Exiting Aspen Plus .....................................................................................4-11

5 Creating a Proces s Flow Diagram

Sta rt ing Aspen Plus .....................................................................................5-2Open ing an Existin g Simula tion .................................................................5-2Switching to PF D Mode ...............................................................................5-3Adding Equipment Icons and Streams........................................................5-4Displaying Str eam Dat a...............................................................................5-8Adding a St rea m Ta ble .............................................................................5-11Adding Text ................................................................................................5-13Pr int ing a Pr ocess Flow Diagr am ..............................................................5-15Leaving PF D Mode ....................................................................................5-16Exiting Aspen Plus .....................................................................................5-16

6 Estimating Ph ysical Properties for a Non-Databank Compone nt

Thiazole Ph ysical P roper ty Da ta .................................................................6-2Sta rt ing Aspen Plus .....................................................................................6-3Crea tin g a Pr operty Est ima tion Simu lation..............................................6-3En ter ing Component s In form at ion..............................................................6-4Specifying P roper ties t o Est ima te ...............................................................6-5En ter ing Molecular Str uctu re......................................................................6-7En ter ing Pr opert y Dat a ...............................................................................6-9


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Run ning a Pr operty Constan t Estim ation (PCE S) ...................................6-14Exam ining Pr operty Constan t Estim ation Results ..................................6-14Crea ting a Pr operty Ba ckup F ile...............................................................6-15Exitin g Aspen Plus.....................................................................................6-16

7 Analyzing Prope rties

Sta rt ing Aspen Plus .....................................................................................7-2Entering Components and Properties.........................................................7-2Gener at ing a Txy Diagra m ..........................................................................7-5

A Connect ing to the Aspen Plus Simulat ion Engine


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7/140Aspen Plus Getting StartedVersion 10 vii

About Getting S tartedBuilding and Running a

Process ModelAspen Plus ma kes it easy to build and r un a pr ocess simulation model byproviding you with a compr ehen sive system of online pr ompts, hyper text h elp,an d expert system guidan ce at every step. In ma ny cases, you will be able todevelop an Aspen Plus process simulation model without referring to printedmanuals .

If you a re n ew to Aspen Plus, you should do all of these Getting S tartedsessions.To fam iliar ize your self with Aspen Plus basics, first do the br ief ha nds-on sessionin Cha pter 1. Then do the six oth er sessions in th is book to lear n st ep-by-stephow to use t he full power a nd s cope of Aspen Plus . Ea ch session requ ires only 20to 30 minut es.

This guide as sum es only th at you h ave a n ins ta lled copy of th e softwa re. If youha ve not inst alled the softwar e, please see th e appr opriat e insta llat ion guide.

Why Use P rocess Sim ulation?

Pr ocess simu lat ion a llows you t o predict t he beh avior of a p rocess by using basicengineering relationships, such as ma ss and ener gy balances, an d phase a ndchemical equilibrium. Given reliable t herm odynam ic data, realistic operat ingconditions, a nd rigorous equipment models, you can simulate actua l plantbehavior. Process simulation enables you to run many cases, conduct "what if"an alyses, and perform sensitivity studies an d optimization r uns . With simulation,you can design bett er plan ts a nd increase pr ofitability in existing plan ts.


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Pr ocess simulat ion is u seful thr oughout t he en tir e lifecycle of a p rocess, fromresear ch an d development thr ough process design to production.

What is an Aspe n P lus P rocess Sim ulation

Model?

A process consist s of componen ts being mixed, separ at ed, hea ted, cooled, an dconverted by un it opera tions. These components a re t ra nsferred from u nit t o unitthrough process streams.

You can translate a process into an Aspen Plus process simulation model by

doing the following steps:

1. Define th e process flowsheet configura tion. To do th is step, you:

Define th e un it opera tions in the process Define the pr ocess str eams tha t flow between th ese unit operat ions Select u nit opera tion models from the Aspen Plu s model libra ry to

describe each unit operation

2. Specify th e chem ical componen ts in th e process. You can t ak e thesecomponents from th e Aspen Plus dat aban ks, or you can define th em.

3. Choose app ropria te ther modynam ic models from those ava ilable in AspenPlus, to represent th e physical properties of the components a nd m ixtu res inthe process.

4. Specify th e componen t flow ra tes an d the th erm odyna mic condit ions (forexample, temper at ur e an d pressur e) of feed strea ms t o the process.

5. Specify th e opera ting condit ions for th e unit operat ions in the flowsheet .

When you ha ve specified this inform at ion, you h ave defined a n Aspen Plu sprocess simulat ion m odel of your process. You can u se th e Aspen Plu s pr ocesssimu lation model to predict pr ocess beha vior.

With Aspen P lus you can int era ctively cha nge specificat ions, su ch as flowsheetconfigur at ion, operat ing condit ions, a nd feed compositions, t o ru n n ew cases a ndan alyze alterna tives.

In a ddition to process simu lation, Aspen P lus allows you t o perform a wide ra ngeof oth er ta sks such as est imating a nd r egressing physical properties, genera tingcustom graphical an d tabular outpu t results, data -fitting plan t dat a tosimu lation models, costing your plan t, optimizing your pr ocess, an d int erfacingresults to spreadsheets.


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Sess ions in this Book

The han ds-on ses sions in t his book a re described in th e following ta ble:

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 simulationflowsheet.

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 Information

Online Help ASPEN PLUS h as a complete system of online help an dcontext-sensitive prompts. The help system contains both context-sensitive helpan d r eference inform at ion. For more inform at ion a bout using ASPEN PLUS h elp,see theAS PE N PL US User Gu id e, Chapt er 3.

AS PEN PLUS Get t ing S t a r t ed Bui ld in g a n d R un n in g a Pr oc ess Mod el

This tu torial includes severa l han ds-on sessions to fam iliar ize you withASPEN P LUS. The guide ta kes you step-by-step to lear n t he full power a nd scope

of ASPEN P LUS.AS PEN PLUS User Guid e The three-volume AS PE N PL US User Gu id eprovides step-by-step procedur es for developing an d using a n ASPEN PLUSprocess simu lation model. The guide is task -orien ted t o help you a ccomplish t heengineer ing work you n eed to do, usin g th e powerful capa bilities ofASPEN PLUS.


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AS PEN P LUS r efe r en ce m a n u a l ser ies ASPEN P LUS reference manu alsprovide detailed technical reference information. These manuals includebackground inform at ion a bout the unit operat ion m odels and t he ph ysicalproperties meth ods an d models a vailable in ASPEN P LUS, tables of

ASPEN P LUS data bank pa ra meter s, group contr ibution met hod fun ctiona lgroups, an d a wide ra nge of oth er r eferen ce inform at ion. The set comprises:

Unit Operation M odels

Physical Property Methods and Models

Physical Property Data

User Models

System Management

S um m ary File Toolkit

AS PEN P LUS a p p l ica t ion exa m p les A suite of sam ple online ASPEN PLUSsimu lations illust ra ting specific processes is delivered with ASPEN P LUS.

AS PEN PLUS In st a l la t ion Gu id es These guides pr ovide inst ru ctions onplatform an d net work installation of ASPEN PLUS. The set comprises:

AS PE N PL US In stal lation Gu id e for Windows AS PE N PL US In stal lation Gu id e for OpenVMS AS PE N PL US In stal lation Gu id e for U NIX

The ASPEN P LUS ma nu als ar e delivered in Adobe porta ble documen t forma t(PDF) on t he ASPEN PLUS Docum ent at ion CD. You can also order prin tedma nua ls from AspenTech.

Tech nical SupportWorld Wide Web For a dditiona l inform at ion about AspenTech products an dservices, check th e AspenTech World Wide Web home page on the In ter net at :

http:/ /www.aspentech.com/

Technica l resources To obtain in-depth technical support information on theInt ernet , visit th e Techn ical Support h omepage. Register a t:

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

Approxima tely th ree da ys after r egistering, you will receive a confirma tion e-ma ilan d you will th en be able to access th is inform at ion.

The m ost cur rent Hotline cont act inform at ion is listed. Oth er informa tionincludes:

Frequen tly asked questions Product tr aining cour ses Techn ical t ips


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Asp en Tech Hot l ine If you n eed help from a n AspenTech Cust omer Sup portengineer , 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 & theCaribbean

+1-617/949-1021

+1-888/996-7001

(toll free)

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

South America

(Argentina office)

(Brazil office)

+54-1/326-9835

+55-11/5506-0756

+54-1/394-8621

+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]

[email protected]

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

Asia & Australia +85-2/2838-6077 +85-2/2833-5642 [email protected]

y y y y


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Aspen Plus Get t ing Star ted 1-

Version 10

Chapter 1

1 Aspen Plus Basics

The best way to learn basic Aspen P lus concepts is by using Aspen Plu s. Thissession leads you t hr ough a n exam ple Aspen P lus simulat ion to explain how to

open a file, ent er dat a, ru n a simulation, an d examine resultsAllow about 20 minu tes for th is session.


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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 10.0-1, 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.

Tip You can creat e a sh ortcut icon for your Windows deskt op th at youdouble-click t o star t Aspen P lus. To crea te t his icon, u se WindowsExplorer t o na vigat e to the xeq folder of your Aspen Plus U serInt erface installation. Next, select t he a pwn.exe progra m a nddra g it ont o your Windows deskt op.

The Aspe n P lus Main Wind ow

The Aspen Plus main window (shown in Figure 1.1) is displayed when you startAspen P lus. In t he workspace of this window you crea te a nd display yoursimulation flowsheet. The workspace rema ins blank un til you en ter problemspecifications.

Aspen Plus displays context-dependent definitions and information in the promptar ea of the ma in window. Whenever you n eed informa tion a bout the cur rent lyhighlighted field or item, r efer t o th e prompt for guida nce.


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Figure 1.1 Aspen Plus Main Window

Open ing a Fi le

You can open a file for an Aspen Plus simulat ion by either :

Double-clicking the file from Windows Explorer Selecting th e Open comma nd from the F ile menu in Aspen P lus

In this section you will use t he 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 indicat

Scroll bars

Next buttonHelp button

Select Mode

button



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

By defau lt, th e Fa vorit es list cont ain s five folders t ha t a re pr ovided with AspenPlus . The files in th ese folders a re designed t o ass ist you in crea tin g suita blesimulation models in Aspen Plus.

Tip You can add folders t o th e Fa vorites list by na vigat ing to the

ap propria te folder an d clicking th e Add to Fa vorites 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 th e simula tion model, th e mouse point er sh ows th e busysymbol, to indicate t ha t Aspen Plus is finishing a n opera tion. When th e opera tionis complete, the mouse pointer retu rn s to the Select a rr ow shape.



Aspen Plus

Basics

Se lecting Flow sh ee t Objec ts

In the main window workspace, Aspen Plus displays the graphical flowsheet forth e opened Flash simulation:

The graphical simulation flowsheet shows the feeds, products, unit operationblocks, an d process str eams. The F lash simu lation h as one feed str eam (str eam1), 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 t he feed strea m (str eam 1) on the sim ulat ionflowsheet an d ent er sp ecificat ions.


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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:

Usin g a Shortcut Men u

A short cut m enu of comm an ds is ava ilable for th e flowsheet objects. To display th eshortcut m enu for stream 1:

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



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.

Ope nin g Inpu t Forms

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

Select Str eams from th e Data men u.

Click th e Strea ms butt on on th e ma in window toolbar. Select Inpu t on the shortcut menu for th e strea m.

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

Tip 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 ulat ion flowsheet inth e Pr ocess Flowsheet window.


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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 sh eet an d form viewer with a h ierarchical menu tr ee view(on t he left side of th e window) of th e available simula tion input , result s, an dobjects that have been defined.

Using Help

When you view a form or a dialog box, you can get cont ext-sensitive help in a ny ofthe following ways:

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

From H elp on t he m ain window menu bar, select What s This? from th e Helpmenu

Press t he Help key (F1)

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

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

Data Browser

menu tree



Aspen Plus

Basics

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 Stream I nput Form at the end ofth 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 also get h elp on a ny topic at an y time by using th e Help men u. Forexample:

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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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 Br owser t o enter da ta on form s. In t his section, you will entermissing temperat ur 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.

Tip Alter na tively, you can select st rea ms 1 (Mater ial) - Dat a Br owserfrom th e Window menu in th e main window to make th e DataBrowser wind ow a ctive.

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 mistak e while typing, use th e Backspace key toera se the previous chara cters.



Aspen Plus

Basics

The completed St rea ms In put Specifications sheet is sh own in t he followingfigure:

When you enter values in boxes or change default options on Input forms, thespecifications you en ter an d th e defau lts you m odify are sh own in black text, a nda check ma rk will appear next to th e sheet name. On th e Specificat ions sheet,the temper at ur e, pressur e, and component flow specificat ions ar e black,indicat ing user input.

Expert Guidan ce the N ex t Func tion

The Aspen P lus expert system, kn own a s th e Next function, guides you t hr ough a llth e steps for en ter ing specifications for your simula tion model. The Next function:

Guides you t hr ough t he r equired an d optiona l input for a simulation bydisplaying th e a ppropriate form s

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

when you cha nge options a nd specificat ions you ha ve alrea dy enter ed

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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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:



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 complet e as in dicat ed by the check ma rk on th e B1folder 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 themessage in the sta tu s bar a t th e bottom of the m ain window.

Close the Data Browser window by clicking the Close button .



Aspen Plus

Basics

Runn ing the Simulat ion

With the input specifications for this simulation model complete, the simulation isrea dy to be ru n. You can ru n t he simu lation in any of th e following ways:

Select Run from the Run menu in the ma in window menu bar

Click th e Star t butt on on the Simulation Run toolbar in th e ma in windowtoolbar

Click the Run Cont rol Pan el butt on to open th e Contr ol Pan el an d then

click th e Sta rt butt on on the Cont rol Pan el toolbar

Click Run on the menu bar.

Aspen Plus displays the Run menu:

Select Run.


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While Aspen Plus performs calcula tions for th e simula tion, the mouse pointer ha sa st op sign sha pe. The block being execut ed is also highlighted in th e simula tionflowsheet in th e Pr ocess Flowsheet window. When t he calcula tions ar e complete,the mouse pointer retur ns to the Select ar row shape. In the sta tus bar at the

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 er rors or war nings, thesta tu s messa ge indicates "Results Available with E rr ors" and"Results Available with War nings," respectively.

Examining Stream an d Block ResultsIn t his section you will view the r esults for t he flash overhea d vapor str eam(str eam 2) and t he su mma ry resu lts for th e Flash 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.



Aspen Plus

Basics

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 methanolan d 40 lbmol/hr water :

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

Right-click to display the stream shortcut menu.

Select Input from the menu.



Aspen Plus

Basics

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 P lus:

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.

Congra tu lat ions! You ha ve successfully complet ed an Aspen Plus sim ula tion.

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Chapter 2

2 Building and Running aProcess Simulation Model

In th is session you will crea te a n Aspen Plus pr ocess model for amethylcyclohexane (MCH) recovery column.

This session is divided into th ree sections:

Building th e Pr ocess Model Adding Dat a t o the Pr ocess Model Runn ing the Simulation

Allow about 50 minu tes t o complete t he en tir e session.



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Building the P rocess Model

In t his section, you will build the pr ocess model by performing th ese ta sks: Define the problem to be simulated Start Aspen Plus Create a new simulation Define the flowsheet using the graphical interface

De fining the P roblem: Meth ylcyclohex ane

Recov ery ColumnThe pr ocess flow diagra m, operat ing conditions, and pr oblem definition a re sh ownin Figure 2.1.

Figure 2.1 Problem Definition: MCH Recovery Column

MCH a nd t oluene form a close-boiling system th at is difficult to separ at e bysimple binar y distillat ion. In t he r ecovery colum n in F igure 2.1, phenol is used toextra ct toluene, a llowing relat ively pur e met hylcyclohexan e to be r ecovered inthe overhea d.



Chapter 2

In t his session, you will evalu at e th e perform an ce of an existing column forrecovering MCH from a feed str eam with a lower concentra tion tha n the origina ldesign condit ions. You can increas e th e phen ol solvent r at e to improve MCHrecovery. However, you n eed to simu lat e th e colum n t o deter mine t he pr oduct

pur ity, column 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 informa tion, see Star ting Aspen P lus in Cha pter 1.

The Aspen Plus Sta rt up 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 th e New dialog box to specify the t empla te a nd Ru n Type for the n ewsimu lation. Use th e Run Type option t o select t he t ype of calcula tions you wa nt toperform. For example, you can perform flowsheet simulation, data regression,

an d pr operty est imation 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 t o Engine dialog box appea rs, see Appendix A.

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

The Aspe n P lus Main Wind ow

The Aspen Plus main 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 inform at ion a bout th e ma in window, refer to th e section, The AspenPlus Main Window, in Chapt er 1.

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



Chapter 2

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 t

In the flowsheet for the MCH process shown in Figure 2.1, there are two feedstreams (MCH-toluene feed and phenol solvent), one unit operation (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 ionblocks in the workspa ce an d conn ecting str eam s to the blocks.

Firs t you will select a u nit opera tion model to simulat e th e extra ctive distillat ioncolumn.

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

Next button



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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 num ber of pictorialicons. You can select t he defau lt displayed in t he Model Libra ry or select a

different icon from th e 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:



Chapter 2

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 efault icon for t he m odel, un tilyou 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.

Tip Alter na tively, you can click t he icon in th e Model Libar y an d th enclick th e ar ea in t he pr ocess flowsheet window wher e you wa nt toplace th e block. Th is met hod a llows you t o place mult iple blocksby clicking d ifferent locations in th e pr ocess flowsheet window.

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

Tip To stop th e au toma tic nam ing of blocks, select Options from t he

Tools menu , click th e Flowsheet ta b an d deselect t heAutomat ically Assign Block N am e option.



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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.

Tip To select a Heat or Work str eam, click t he down ar row next to theMater 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.



Chapter 2

Ports th at m ust h ave at least one stream conn ected ar e shown in red. Optiona lports a re sh own in blue. If you position t he m ouse point er over a port for a fewseconds, th e ar row is highlight ed an d a description of the port a ppears.

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 theprocess 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.

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



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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 the

left 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 connect t he 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.

Tip To can cel connecting the st rea m a t a ny time, press E SC.To delete a str eam, select t he st ream in th e graph ical flowsheetan d press th e Delete key.

Your gra phical simula tion flowsheet is now complete. The st at us indicat or in thebott om r ight of th e ma in window says "Required In put Incomplete" indicatingtha t furt her input specificat ions a re r equired for t he simulat ion.


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Adding D ata to the P rocess Mode l

Now that you h ave defined your flowsheet gra phically, use t he Dat a Browser inpu tform s to enter t he rem aining required inform at ion for t his ru n.

You can rely on t he Aspen Plus Next fun ction t o display th e requir ed inpu t form s.As an altern at ive, you can display th e input form s by:

Selecting th e appropriate form s from th e Data menu Clicking th e appr opriat e butt on on th e Data Browser toolbar

in the m ain window Selectin g an object in the gr aph ical flowsheet an d clicking Inp ut on the

shortcut menu Double-clicking an object in t he gra phical flowsheet

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



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For t his section, you will use th e Next fun ction.

Click the Next button in the main window toolbar.

Aspen Plus displa ys a dia log box telling you t ha t your flowsheet is complete an dtha t you ar e now ready t o provide rema ining specificat ions t hr ough t he inpu tforms.

Click OK to display the first required input form.

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

form s. The Data Browser window title bar conta ins th e form na me.

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



Chapter 2

Spe cifyin g Title , Stream P roperties , an d

Units

The Setup Specificat ions form displays some of th e defaults Aspen P lus uses for t heother simulation form s. (Global defaults a ppear on all subsequent form s, but youcan override t hem .) You will use th e Global sheet t o give your simu lat ion a tit le.You can also review the other global options t ha t were set wh en you selectedGeneral with En glish Un its as the 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 t he r ema ining boxes on t his sh eet est ablish global defaults foryour simulation input. For t his session you will use En glish un its an d th e otherdefaults , so you do not need t o 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 always calculates temperature, pressure, vapor fraction, molecularweight a nd t ota l flow, entha lpy, entropy, an d density for t he simulat ion st rea ms.Becau se you selected th e Genera l with En glish U nits Applicat ion Type when youcreat ed th is ru n, Aspen Plus will also calculat e componen t m ole flow by defau lt.

Click the Stream tab to view the Stream sheet.

On t he St ream sheet, you can specify which a dditiona l properties you wa ntAspen Plus to calculat e an d report . The componen t flow an d fra ction ba ses an dadditiona l properties requested on t his form will be included in th e Str eam-Summar y 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 calculat e an d report a dditiona l strea mpropert ies. A nu mber of sets of add itiona l propert ies ar e built in t o Aspen Plus foreach applicat ion t ype, as Pr operty 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, cont ains 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 Compone nts

You use t he Component s Specificat ions Selection sheet to select t he chem icalcomponents pr esent in t he simulat ion.

The components for the process in this example are toluene, phenol, andmethylcyclohexane. 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 t he Ba ckspace key to erase. )

Becau se Aspen Plus recognizes the componen t n am e Toluen e as a n Aspen Plus

dat aban k component, Aspen Plus fills in th e Type, Component Nam e, andFormula boxes automatically.

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

Aspen Plus aga in fills in t he Type, Componen t Na me, an d Formu la boxes.



Chapter 2

For met hylcyclohexa ne, use t he a bbreviat ion MCH for t he componen t 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 m ust a lso enter a da tabank formu la or da taban k na me to retrieve theappr opriat e component da ta from the Aspen Plus databa nk.

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

The Fin d dialog box appea rs, listing all the componen ts in t he Aspen Plusdat aban k th at ha ve a na me conta ining the letters you t yped, METHYLCYC:

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

Tip To view the complet e componen t n am e, click a nd slide th e rightedge of th e componen t n am e column label to the 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 inu e a dding componen ts from th is dialog box or closeit .

Tip If you n eed to sear ch for componen ts ba sed on molecula r weightra nge, boiling point ra nge, or CAS num bers, you sh ould use th eAdvan ced sheet in t he F ind dialog box.

Click Close to return to the Components Specifications Selection sheet.

You ha ve now specified the t hr ee componen ts r equired for th is processsimula tion model, Toluene, P hen ol, and Meth ylcyclohexan e.

Click the Next button on the Data Browser window toolbar.

The Aspen Plus expert system displays th e next r equired sheet, th e Pr opertiesSpecifications Global sheet.

Selec t ing The rmodyn amic Meth ods

Use th e Pr operties Specificat ions Global sheet to select t he th ermodynamicmeth ods used t o calculat e properties such a s K-values, ent ha lpy, and density.Property met hods in Aspen P lus ar e ar ra nged according to Pr ocess Types an d inlogical gr oupings called Base Meth od.

For t his simu lat ion, use t he U NIF AC activity coefficient model to estima te

liquid-phase 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.



Chapter 2

You can get basic inform at ion about a base m ethod by using the mouse or th ear row keys to move to the ba se meth od an d reading th e prompt. For m oreinforma tion a bout a base m ethod, you can m ove to the ba se meth od na me an duse 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 Required P ropert ies Inpu t Complete dialog box appea rs. This dia log boxallows you to select additional input forms for physical property parameters andestimation.

However, th e pr operty specificat ions for th is problem a re complete, so you cancontinu e to th e next required input.

Click OK to close the dialog box.

Entering Strea m Data

The Strea m Inpu t Specificat ions sh eet for St rea m 1 appea rs, as indicated in theData Browser window title bar. Str eam 1 will be the MCH-toluene feed strea m.

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



Chapter 2

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 da ta for St ream 1, as indicat ed by the In putComplete message in the Da ta Browser sta tus bar, at the lower left of the

window.

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

The Str eam Specificat ions form for St ream 2 appear s, 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 Ope ration Block Da taOn th e RadFr ac Setup Configura tion sh eet, you ent er th e num ber of theoreticalsta ges, th e valid phases in th e column, t he distillat e vapor fraction, an d otheroperat 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 youth at t he sheet is not yet complete and you must en ter some additiona lspecifications.

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 tyou n eed to enter Nu mber of sta ges, Condenser type, an d two out of a list ofspecificat ions, in order to complete th is sheet :



Chapter 2

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 defau lt of Vapor-Liquid for Valid ph ases is corr ect for th is problem becausewe expect only a vapor ph ase a nd one liquid phase.

The blue check mar k n ext to the Configur at ion t ab indicat es th e sheet iscomplete.



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The RadFr ac column m odel requires more th an one sheet t o enter the n ecessaryinformation. The expert system displays the Streams sheet, on which you specifyfeed an d product st age locations.

In t he RadF ra c model, sta ge 1 is th e top stage (condenser ) and st age N (where Nis the n um ber of sta ges) is the bottom st age (reboiler). For th e process th at youare simulating (shown in Figure 2.1), the MCH-toluene feed (stream 1) enters

above sta ge 14, and th e phenol solvent str eam (str eam 2) ent ers a bove stage 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:



Chapter 2

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

On th e next required sh eet, the Pr essure sh eet, you will enter the columnpres sur e pr ofile. You m ay en ter a s ta ge-by-sta ge profile, or specify a t op-stagepressur e an d a pr essure dr op for t he rest of the column. For th e MCH recoverycolumn in th is example, use a condenser pressur e of 16 psia, and a reboilerpressur e of 20.2 psia. In t he simu lation, Aspen Plus will interpolat e th e pressur eof the interm ediate sta ges.

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 Pr essure sheet is n ow complete.



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The Inpu t Complete message in th e Data Browser sta tu s bar in the lower left ofth e window, indicates t ha t you ha ve completed th e requ ired specificat ions for t hecolumn model.

All the requ ired form s for t he flowsheet ar e now complete. You can still ent erspecifications on optiona l inpu t forms. You can also go back t o any of the r equiredform s and m ake chan ges.

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, andBlocks folders indicate that these required forms are complete.

The r ema ining inpu t folders Reactions, Convergen ce, Flowsheeting Options, an dModel Analysis Tools are optional

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


The Requir ed Inp ut Complete d ialog box confirms th at all requ ired specificat ions

ar e complete, and pr ompts you to run the simu lation:



Chapter 2

Runn ing the Simulat ion

To ru n th e simu lation:

Click OK on the Required Input Complete dialog box.

Aspen Plus displays the Control Panel.

The Cont rol Panel a llows you t o monitor a nd int eract with th e Aspen Plussimu lation calcula tions. For more inform at ion on h ow to contr ol th e simula tionth rough the Control Panel, 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 Help.

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

Pr ocessing inp ut specifications Calculations begin Generat ing results

As Aspen Plus execut es th e simulation, statu s messages appea r in th e Contr olPa nel. When t he simulat ion h as completed, the messa geResu lt s Availableappear s in the sta tus bar at t he bott om of th e main window.



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Examining Simu lation Resu lts

When theResu lts Avai lable message appears in the st atu s ar ea, you can examineth 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 Resu lts

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 m enu 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 Summar y sheet reports asumm ar y of column results, su ch as condenser an d r eboiler du ties:



Chapter 2

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 temper at ur e, pressure, enth alpies,an d flow profiles for th e RadF ra c column :



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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 t he Composition s heet , when th e Liquid View is selected, liquid composition(as mole fra ction) profiles are sh own for t he Ra dFr ac colum n:

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



Chapter 2

Examining Stream Resu lts

You can display calculat ed str eam results by selecting a str eam directly from th egraphical simulation flowsheet.

To display th e gra phical flowsheet , first close the Da ta Browser window:

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 St ream 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 the r esults for St rea m 3. In a ddition t oth e ther modyna mic sta te a nd flow results for t he str eam, th e properties you

requested on t he Setu p 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 forStream 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 Mater ial sheet displays results for St ream s 3, 4, and 1:

Fr om t he component flow rat es reported in th e strea m r esults, you can deter mineth at th e met hylcyclohexa ne r ecovery overhea d is 97%.

Chan ging Inpu t Specificat ions

In t his section, you wa nt to see the effect of increa sing th e solvent flow ra te on th epur ity an d recovery of met hylcyclohexane. To increase th e phen ol solvent st rea mflow ra te 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.



Chapter 2

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.

Rerunning the Simulat ion

To rer un t he model with the chan ged input :

Click the Next button on the main window toolbar.

The Required In put Complete dia log box appea rs t elling you t ha t you inpu t iscomplete an d asking if you wan t t o run t he simulat ion with t he newspecifications.

Select OK to run the simulation.

The Cont rol Panel appea rs a gain, and t he column calculat ions a re completedusing th e new ph enol flow ra te.

Display the block and stream results for the new conditions, as previouslydescribed. You will observe t ha t in creasin g th e solvent flow ra te from 1200 to1800 lbmol/hr increases th e MCH pur ity in th e overhea d product to 98.4% andth e MCH recovery t o 98.4%.

To choose th e optimal condit ions, it would be h elpful t o gener at e a sensit ivityta ble of MCH r ecovery an d pur ity versus phen ol flow ra te. This exam ple is inChapter 3.



Building

and

Running a

Simulation

Model

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.

You can open t his file with a text editor or you can pr int t he file. By default, th ereport file mch.rep is saved in your workin g directory (displayed in th e Save Inbox). You can select a noth er dir ectory by na vigat ing to it usin g th e Save In box.

Tip You can a lso examin e th e report by selectin g Report from t heView men u on t he m ain window. The Report dialog box allows



Chapter 2

you t o select which section of the r eport you wan t d isplayed in atext editor (selecting the simulation will display the entirereport).

Exiting Aspen P lus

When you a re finished work ing with t his model, you can exit Aspen Plus as 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 yourdefault 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.

Congrat ulations! You ha ve just built an d r un a complete simulat ion model usingAspen P lus.

y y y y



Building

and

Running a

Simulation

Model



Chapter 3

3 Performing a SensitivityAnalysis

One of th e benefits of using a pr ocess simu lation model is tha t you can quicklystu dy the sen sitivity of process perform an ce to cha nges in process opera tingvar iables. With Aspen Plus, you can allow simu lat ion inpu ts t o var y, an d canta 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 a na lysis withAspen P lus.

Allow about 20 minu tes for th is session.

This session assumes that you have successfully completed themet hylcyclohexan e (MCH) recovery column simula tion in Chapt er 2, an d th atyou 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 th e Chapt er 2 example, you can open a backup file from th eAspen Plus Examples folder as described in Opening an Existing Simulation, thischapter.



Performing a

Sensitivity

Analysis

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 Sta rt up dialog box appear s.

Ope nin g an Existing Simu lation

If you saved t he m eth ylcyclohexane (MCH) recovery column simula tion creat ed inChapter 2:

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

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

Select mch.apw in the list and click OK.

If your saved file mch.a pw is not displayed in th e 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 t o Engine dialog box appea rs, see Appendix A.

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

If you did not create the MCH simulation in Chapt er 2, you can open t he backupfile mch.bkp in th e Exam ples folder.



Chapter 3

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 files and folders displayed, navigate to theExamples folders in the Aspen Plus user interface installation directory (e:\ProgramFiles\AspenTech\Apui100\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 simulat ion sta rt ing from t he MCH columnsimulat ion, creat e an d save a copy of the MCH simu lat ion file with a new filename, MCHSENS. Then you can modify this 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 thebase case simulation, MCH.



Performing a

Sensitivity

Analysis

De finin g the Se ns it ivity Analysis

In t he base case MCH simulat ion in Cha pter 2, you simu lated t he MCH r ecoverycolumn performa nce at t wo values for t he ph enol solvent flow ra te (1200 and 1800lbmol/hr). In the sensitivity analysis, you will want to tabulate methylcyclohexane(MCH) distillat e product pu rit y (mole fra ction), as well as condenser dut y andreboiler dut y, for severa l different flow rat es of phen ol.

Entering Sen sit ivity Spe cifications

To enter sens itivity specifications, use S ensit ivity form s, which you a ccess from theData 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.



Chapter 3

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 wa ntto look at , the input s you wan t t o vary, and h ow Aspen Plus ta bulates th e results.

De finin g Sample d Variables

On t he In put Define sheet, you select t he simulat ion var iables you wa nt tosam ple for t he sensitivity an alysis an d give each var iable a unique na me. In th isexample you will define the MCH distillate product purity, the condenser duty,an d the r eboiler dut y as sampled variables.

To select the MCH distillate pr oduct pur ity as a sampled 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.



Performing a

Sensitivity

Analysis

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 list box.

Click the Component list box to display a list of valid components. Select MCH.

The blue check mark next to XMCH in the Variable Name list box indicates that thedefinition of variable XMCH is complete.

Click the Close button to close the Variable Definition dialog box and return to theDefine sheet.



Chapter 3

You ha ve specified th e first sam pled var iable, XMCH:

To select t he condenser duty a s a sampled variable:

Click the New button.

In the Create New Variable dialog box, enter QCOND in the Variable Name box. ClickOK to continue.

Since condenser duty is a scalar result for the RadFr ac block B1, this sa mpledvar iable belongs t o the Blocks category an d is of type Block-Var.

Click the Blocks option under Category.

Click the Type list box to display the flowsheet variable types that can be accessed forblocks.

Select Block-Var for Type.

In the Blocks list box that appears, select block B1.

Click the Variable list box to display the list of variables. Move through the list and lookat the descriptive prompts.

Select COND-DUTY for Variable since it represents the result of interest.



Performing a

Sensitivity

Analysis

Aspen Plus automatically fills the Sentence box based on your choice of variable.

The definition of th e var iable QCOND is n ow complet e.

You ha ve crea ted t wo new sa mpled var iables (XMCH an d QCOND) usin g the

New butt on on th e Define sheet. To illustra te a nother way to creat e sam pledvar iables, you will now use t he Var iable Na me list box in th e Variable Definitiondialog box to define th e colum n r eboiler dut y as a sam pled varia ble.

Click the Variable Name box and select New.

Tip You can also right-click on t he Var iable Na me box and selectCreat e from the popup menu .

The New item dialog box appears.

In the Create a New Item box enter QREB, the name of the new variable that you wantto define. Click OK to continue.

You are returned to the Variable Definition dialog box with QREB displayed in theVariable Name box.

Reboiler duty is also a Block variable of type Block-Var.

Click the Blocks option button under Category.

Select Block-Var in the Type list box.



Chapter 3

Select B1 for Block and REB-DUTY for Variable.

The definition of variable QRE B is n ow complete.

Click Close to close the Variable Definition dialog box and to return to the Definesheet.

You have identified the three process variables to sample for the sensitivityan alysis and given each a un ique name.

Click the Next button.

The expert system displays the next required sheet, the Vary sheet.

De finin g Manip ulate d Variables

On th e Input Var y sheet, you define th e simulation var iable to be man ipulatedfor t he sen sitivity ana lysis, identify th e varia ble valu es to be used, a nd specifyth e labels for t he variable to be used in t he ta bulated r esults. In th is exam ple,you will manipulat e th e molar flow ra te of th e phen ol feed str eam (str eam 2).

Click the Variable Number list box, select to create a new manipulatedvariable.

Aspen Plus creates the manipulated variable and displays the ID 1 in the VariableNumber list box.

Click the Type box to display a list of valid variable types.

Select Stream-Var for the Type.

Aspen Plus displays the remaining fields necessary to uniquely identify the flowsheetvariable.

Select 2 for the Stream.

Select MOLE-FLOW for the Variable.



Performing a

Sensitivity

Analysis

For t his session, you will var y the flow ra te bet ween 1200 an d 2000 lbmol/hr atincremen ts of 100 lbmol/hr:

Click the Overall Range option button.

Move to the Lower box and enter 1200 for the bottom of the range.

On the Upper box, enter 2000 for the top of the range.

On the Incr field, enter 100 for the increment size.

For t his session, you will specify PH EN OL FLOWRATE a s th e label for t hemanipulated variable.

Enter the label PHENOL for Line1 and FLOWRATE for Line2 of the Report labels.

You ha ve specified the informa tion for th e ma nipu lat ed process var iable:

Click the Next button.

The Tabulate sheet appears.



Chapter 3

De finin g Tabulated Variables

On t he Tabu late sheet , you specify the var iables to be tabu lated by the sen sitivityan alysis, and s upply optiona l hea dings for t he t able column s. You can choose

from am ong th e variables tha t you defined on t he Sensitivity Inpu t Define sh eet.You can also tabu lat e an y algebraic combinat ions of th ose var iables.

To ta bulat e MCH distillate composition:

In the Column Number box, enter 1, indicating that this is the first tabulated variable.

A second row opens up in the table to define a second tabulated variable.

On the Tabulate variable or expression box, in the first row enter XMCH.

To specify column labels for th e ta bulat ed MCH distillate composition:

Click the Table Format button, the Table Format dialog box appears.

Enter the label MCHPURITY IN DIST on the column label field in the first column, asshown:



Performing a

Sensitivity

Analysis

Click Close to close the Table Format dialog box.

To ta bulate t he column condenser duty a nd r eboiler du ty:

On the Column Number box in the second row, enter 2.

Enter QCOND for the Tabulate variable or expression field.

On the next Column Number field, enter 3.

Enter QREB for the Tabulate variable or expression field.

You ha ve now defined th e th ree var iables to be ta bulated in your Sensitivityanalysis.



Chapter 3

To specify th e column labels for condenser dut y an d reboiler d ut y:

Click the Table Format button.

Enter the label CONDENS DUTY in the column label boxes under Column Number 2.

Enter the label REBOILER DUTY in the Column label boxes under Column Number 3.



Performing a

Sensitivity

Analysis

Close the Table Format dialog box.

The In put Sta tu s for Sen sitivity block S-1 (th e blue check m ar k on folder S-1 inth e left pan e of Data Browser window) shows tha t all required inpu t is complete.

Runn ing the Simula