aspen tutorial reaction

8/3/2019 Aspen Tutorial Reaction

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Aspen TutorialChBE 431Spring 2005

Author: Joseph Zakzeski

Getting Started 2

Setup 2

VLE diagrams 4

Reactions 6

The Reactor 8

Separation: Flash Columns 11

Distillation Columns 12

Heat Exchangers 17

1


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Getting started

ClickAspen Plus User Interface icon and enter password once the simulator finishes initializing. Save

the file as a new file name and SAVE OFTEN with different versions (ie save as design1, make a change,

then save the new design as design2. If something goes wrong, then, its still possible to go back to

design1 and fix problems).

The simulator will open with the following screen after the password has been entered.

Setup

First, click the Data pull-down menu then clickSetup. This section allows the title, base units, and other

characteristics to be manipulated. Name the project and switch to the appropriate units. Note the toolbar

on the left part of the screen displayed in outline form. The rest of the system properties can be specified

using this toolbar by simply going down the list until all the sections have BLUE checkmarks.

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After finishing the initial setup, click on the Components section to define the species present. Click the

box under component ID and type in the name of the component (ie hydrogen or water). Select the type

(typically conventional). The Tab button can be used to move to remaining sections. The simulator will

input the component name and formula automatically if the species is present in the database. Enter all

elements accordingly.

3

Toolbar1: Name the

Project

2: Set the units

3. Set globalproperties

Select

Components

1: Type in compound ID

(ie hydrogen)

2: Select type (usuallyconventional)

3: Ensure that compound

name and formula are

correct


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After the components are entered, select Properties and Specifications on the toolbar. This section is

where the THERMODYNAMIC MODEL is selected. First, select an appropriate thermodynamic model

for that adequately models the components present. Using a correct thermodynamic model is crucial

because the entire separation system will be based on it. Select the thermodynamic model in the Base

Method section. Depending on the model chosen, the simulator should input the remaining required

information. Enter in any necessary information if required in the appropriate section. The section iscompleted when blue checkmarks appear on the screen.

VLE diagrams

Make sure to check the VLE diagrams to make sure that the boiling points, and components of the mixtures

match the components and that theres no unusual occurrences. To check the VLE diagrams, after

selecting the model, go to Tools, then Analysis, then Property, and finally Binary.

4

SelectSpecifications

under

Components

Select the

thermodynamic model

in the Base MethodSection


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Select the analysis type (typically Txy) and the components of interest. Setup the computer to use mole

fraction based on a particular component, and under the property method select the thermodynamic model

used. Select Go to get the Txy diagram, which should be analyzed for accuracy.

5

1: Set Txy

diagram

2: Select

Components

3: Select Basis

and Component

4: Select phases

(typically Vapor

Liquid)

5: Set the pressure

(or temperature)

6: Select the

thermodynamic model

7: Select Go


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Reactions

The next step is to enter reaction stoichiometry and chemical kinetics. Scroll down on the toolbar to the

folder marked Reactions. Click Reactions, then click the subfolderReactions. A new screen should

appear. Click the New button.

On the next screen, hit the New button and fill in the information on the Edit Reaction Screen. Enter the

Reactants and the appropriate coefficients (Aspen automatically places a minus sign on the reactants) along

with the products. When the stoiciometry is correct, hit the Kinetics Tab

6

Click

Reactionsand then

subfolder

Reactions

1: Click the New

button

2: Name the

reaction

3: Select the

reaction type

4: Click OK

Ensure no unusual

behavior (like spikes)

and that boiling points

match


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Under kinetics, select the appropriate reaction, select the phase (ie vapor), and enter the kinetic parameters.

Do not fill in the To space. When all the parameters have been entered, select Driving Force.

Under driving force, enter the appropriate basis (ie partial pressure for gases) for term1. Enter the correct

coefficients based on the kinetics (typically the reactants have a 0 exponential unless theyre present in the

rate equation). For the coefficients for driving force, unless theres a temperature dependence known, enter0s for all parameters. Under Term 2, the exponentials of all components is typically set at 0. Select Next.

7

1: Hit New

2: Enter

Reactant

3: Enter coefficient

4: Select

Reaction Type

(usually kinetic)

5: Enter

Products and

Coefficients

6: Click Next

7: When finished, select

Kinetics Tab

1: Select

Reaction

2: Select

Phase

3: Enter kinetic

Parameters (ensure

units are correct)

Leave To

blank!

4: Select

Driving force


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The Reactor

At this point, the simulator is now ready for the unit operations. The best and place to start is with the

Reactor since this component is the most important in the process. On the main screen, select the Reactors

tab, click on the icon for the desired reactor (ie RPlug), and click on the screen to place the reactor. On the

far left part of the screen is a materials stream button. After placing the reactor, click on the material screen

and click on the blue arrow either entering or leaving the reactor to place the stream. Left clicking places

the streams, and right clicking deselects the materials button. To delete the reactor, simply right click the

icon on the screen and select the Delete Block option on the menu.

8

1: Select Basis and Term

2: Set ex onentials

3: Select coefficients

4: Set up Term 2 in

kinetic reaction

5: Select Next

1: Select Reactors tab2: Click reactor and lace

3: Click materials

button and place

streams

Note: Reactants enter

the Top in the Blue

arrows. Coolant streams

enter through the Red

arrows


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Double click the stream entering into the reactor to specify its components. Select the appropriate

temperature and pressure along with the species present in the stream. Click next when finished.

The next step is to setup the reactor block. Select Blocks on the outline on the left. Select Setup. Select

the desired reactor type (ie isothermal, adiabatic, etc.). When finished, click configuration.

Enter the reactor length and diameter under configuration. Aspen uses these values to calculate conversion.

Click the Reactions tab when finished

9

1: Double

click stream

2: Set Temperature

and Pressure

3: Specify

components

4: Ensure Total flow

equals Total flow

5: Click Next

1: Select

Blocks

2: Select theReactor and

then Setup

3: Select theReactor type and

enter necessary

information

4: When finished,

Click

configuration


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Under the reactions tab, simply select the reactions that are occurring in the reactor by double clicking the

reaction. Clicknext.

At this point, the simulator will attempt to converge the process flow diagram. Click OK and the computer

will run the simulation. To view the results of the process, double click the reactor or the stream leavingthe reactor to determine the species present.

10

1: Enter

length and

diameter

2: Select

Reactions

Ensure correct phases

are allowed

1: Select

Reactions

2: Click Next


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Separation Flash Columns

In order to insert separation units, select the Separators Tab and select the desired unit. Place on thescreen as was done with the reactor. Right click the stream leaving the reactor and select Reconnect

Destination. Click on the separator to connect the stream. Finally, select the materials button and create

any other necessary streams. The example used is a flash column. Double click the flash column to set the

specifications including temperature and pressure. Clicknext to run the simulator. (NOTE: Flash Columns

cannot be sized in ASPEN to the best of my knowledge!)

11

1: Double

Click stream

Species present

in stream

Three possibilities:

Error (red = plant blows up)

Results Available with Warnings(yellow = caution)

Results Available (blue =happiness)

1: Select

Separators

2: Place

Separator andReconnect Stream

Destination

3: Double click

separator and set

specifications

4: Click Next to

run Simulator


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Distillation Columns

Its best to start with a short-cut column before using a rigorous column in order to first acquire some

necessary information. First, click the columns tab and place the short-cut column on the screen. Connectthe stream similarly as was done with the flash column.

Double click the short-cut column to designate the specifications. Designate the column specifications (use

correlations). Clicknext to converge.

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1: Click

Columns Tab

2: Place short-cut

column

3: Reconnect

Streams

1: Set

specifications

2: Consider if itsbetter to have

Total or Partial

Condenser

3: Click Next


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Once the simulator converges and the system has adequately separated the components (takes some trial

and error), double click the short-cut column again. On the outline on the left part of the screen, click onresults and record the information. This information will aid in designing the rigorous column.

Delete the short-cut column and replace with the RadFrac column. This column is much more rigorous

(and also more difficult to converge). Use the information from the short-cut column to help design the

rigorous column.

Double click the RadFrac column. Under the Configuration Tab, enter the number of stages, select the

condenser type, distillate rate, and reflux ratio. Click the Streams tab when finished

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1: Double click

short-cut column

2: Click on Blocks,

The Distillation

Column, and then

Results3: Record all

information

4: When satisfied,

DELETE short-cut

column (save as a new

name in case you need to

go back)

1: Install

RadFrac

2: Reconnect

Lines


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On the Streams section, enter the feed stage and also where on the stage the stream enters (typically on

stage or above stage). Click the Pressure Tab.

In the Pressure Screen, designate the condenser pressure and clicknext. The Simulator should now attempt

to converge the Distillation Column. Check the outlet streams to ensure that the compositions the

conditions (Temperature and Pressure, etc.) are acceptable in each stream by double clicking the streams.

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1: Double

Click

RadFrac

2: Enter #

of Stages

3: Enter

Condenser,

Reboiler, andPhases

4: Input Operating

Specifications

5: Click the

Streams Tabwhen finished

1: Input Feed

Stage and

Convention

2: Ensure phases are

correct

3: Click Pressure

Tab


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In order to find the important information about the column, double click the column and select Results

Summary for condenser/reboiler duties and other information. Read through the other tabs for other

important or necessary information.

In order to size the trays, on the menu on the left, click the Tray Sizingfolder. On the screen that appears,

click the New button. A Tray Sizing Section Number should appear. Simply Click OK.

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1: Enter

Condenser

Conditions

2: ClickNext

1: Double

click

column

2: Click

Results

Summary

3: Admire what a

sweet column this is


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Aspen sizes the distillation columns on a single tray basis. Simply select a starting tray (ie 6) and an ending

tray. Also input the tray type. This section also indicates the spacing between the trays. Once everything

is designated, clickNext to converge the PFD.

After the simulator converges, double click the distillation column. The Tray Sizing folder will now have

a bluish color. Click the folder. On the new screen, select the box that says Results Available and hit the

edit button.

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1: Select

Tray Sizing

2: Click New

3: Select a

number and

press OK

1: Select

Starting Tray

(ie 6)

2: Select

Ending Tray

(ie 7)

3: Select tray

type

4: Click Next

Tray

Spacing

indicated

here


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On the new screen, click the results tab. The column diameter is listed on this menu.

Heat Exchangers

To insert a heat exchanger, click on the Heat Exchanger Tab and place the desired heat exchanger on the

screen (HeatX is the rigorous exchanger. Use this type rather than starting with a shortcut exchanger). TheHeatX exchanger requires both the shell side and tube side streams. If cooling, for example, without using

heat integration, simply designate the stream a water stream at the desired temperature by double clicking

the stream and filling in the appropriate information.

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1: Doubleclick

distillation

column

2: Click

Tray Sizing

(now blue)

3: Click

ResultsAvailable

4: Click Edit

1: Click

Results Tab

2: Record

Column

Diameter


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For the unspecified stream, just enter the desired temperatures and flowrates, then close the box

Double click the heat exchanger to specify the parameters. A shortcut calculation should suffice. Specify

the stream conditions (ie, hot stream outlet temperature, cold stream outlet temperature), and ensure that the

minimum approach temperature is AT LEAST 10K. When finished at this screen, select pressure drop.

18

1: Select Heat

Exchangers Tab

2: Place Heat X

(rotate if desired)

3: Connect Material

Streams

4: Double click

unspecified

Stream

1: Enter

Temperature

2: Enter

Pressure

3: Enter species

and total flowrate

4: Close the box


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Specify the pressure drop that occurs in both the hot and the cold side of the exchanger. Click U Methods.

Select and appropriate U term for the system (depending on if the species are both liquids, liquid/gas,

condensing gas, etc.) Clicknext to converge PFD.

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1: Enter

Specification

2: Ensure minimum

approach temperature

at least 10K

3: Click Pressure

Drop

1: Designate

Hot or Coldside

2: Specifyoutlet pressure

3: Click U

Methods


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Double click the Heat Exchanger. Click the Thermal Results listing on the Outline, and clickExchanger

Details to find the heat duty and exchanger area. Make sure to check the streams leaving and entering the

exchanger to ensure appropriate conditions.

You should now have enough of the basic tools to design a chemical system using ASPEN. Several otherunit operations are available and can be placed and used similarly. Make sure to save often when making

changes under new file names because its easier to make changes to a working diagram than it is to fix and

make changes to one that doesnt work. Good luck!

1: Select

Appropriate U

(watch units!)

2: click Next

1: Double

Click Heat

Exchanger

2: Click Thermal

Results

3: Click

Exchanger

Details

4: Note

Duty, Area,

U, and otherinfo

5: Check actual streams to

ensure appropriate conditions

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