aspen flarenet getting started

8/12/2019 Aspen FLARENET Getting Started

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Aspen FLARENET

2004.1Getting Started Guide


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1 Getting Started 2

Contents

1 GETTING STARTED ...................................................................................... 4Overview ................................................................................................................ 4Data Requirements .................................................................................................. 5

Pipe Segment Data.............................................................................................. 5Relief Source Data............................................................................................... 6System Design Constraints................................................................................... 7

Starting FLARENET................................................................................................... 8Starting A New Model ............................................................................................. 10Saving The Model................................................................................................... 13Building The Pipe Network....................................................................................... 14Defining The Scenarios ........................................................................................... 23Defining The Sources.............................................................................................. 27Rating The Network................................................................................................ 34Printing Data And Results........................................................................................ 36

2 DEVELOPING THE MODEL.......................................................................... 37Overview .............................................................................................................. 37Data Requirements ................................................................................................ 37

Pipe Segment Data............................................................................................ 37Relief Source Data............................................................................................. 38System Design Constraints................................................................................. 40

Opening the Old Model............................................................................................ 40Updating the Model ................................................................................................ 41Defining The Scenarios ........................................................................................... 48Defining The Sources.............................................................................................. 50Sizing the Network................................................................................................. 54Design Calculations ................................................................................................ 55

GENERAL INFORMATION............................................................................... 59Copyright.............................................................................................................. 59Related Documentation........................................................................................... 60


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1 Getting Started 3

TECHNICAL SUPPORT.................................................................................... 61Online Technical Support Center .............................................................................. 61Phone and E-mail................................................................................................... 62


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1 Getting Started 4

1 Getting Started

OverviewThis Getting Started tutorial shows the fundamental principles involved inusing FLARENET to design and rate a new flare system. This "guided tour" will

expose you to most of the major features of FLARENET.

This tutorial assumes that you are familiar with the use of Windows and havesome prior experience in the design of flare systems.

This example consists of the following main parts:

1 Building The Pipe Network -Pipes and nodes will be added using eitherthe PFD or the Manager views.

2 Defining the Scenarios -Different scenarios will be set up to simulate

various process conditions.

3 Defining The Sources -Relieving sources will be added to each scenario.

4 Sizing the Network -Finally, the pipe network will be simulated and

results will be viewed both in textual and graphical form.


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1 Getting Started 5

Data RequirementsBefore you can start to build a computer model of the flare header system,you must first define all the data that will determine your system.

Pipe Segment Data

Data Description

Connectivity You would normally have prepared a system sketch that defines thenodes to which the pipe segments are connected.

Length and fittingsloss coefficients foreach pipe segment

These will be based upon either a preliminary or detailed isometricdrawing of the piping.

Diameter and pipeschedule for each pipe

segment

If you are rating an existing network, these will normally be takenfrom the flare system P&ID. If you are sizing a new flare system, the

pipe diameters that you define are relatively unimportant since theywill be overwritten by the sizing algorithms. It is recommended thatreasonable diameters be defined, so that the sizing algorithminitializes to a condition that will give faster convergence.

The following diagram shows the connectivity of the system that you will be

designing in this example.

Fig 1.1

When you aresizing a flaresystem, the initialpipe diameters mayaffect the solutionwhen there is aliquid phase andthe liquid knockout

drum is modeled.You should initiallysize a networkusing vapor phasemethods.


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1 Getting Started 6

The piping in the network diagram is detailed in the following table:

Item Length(m)

InternalDiameter(mm)

WallThickness(mm)

FittingsLoss

ElevationChange(m)

Flare Tip 3.0 0Stack 100 876.3 19.05 0 100

Header 3 50 876.3 19.05 0 0

Tail Pipe 1 25 428.65 14.275 0 0

Tail Pipe 2 25 428.65 14.275 0 0

The flare tip is not a pipe segment, but rather a node that represents a zero

length piece of pipe with defined fittings loss coefficients. Since the internaldiameter is not specified it will assume the same diameter as the upstream

pipe segment. Fittings loss coefficients for the flare tip exclude pipeenlargement and junction losses for the connect to the upstream pipe which

will automatically be calculated.

Relief Source DataThe following data must be specified for the sources:

Data Description

Flow and Composition These may vary for each scenario that you are evaluating. If a reliefsource is not used in a particular scenario the flow may be set to zero.The Flow refers to the quantity of fluid that the source valve mustpass as a consequence of the plant upset condition. The Rated Flowrefers to the quantity of fluid that the source valve will pass due to itsphysical construction. Rated flow must always be greater than orequal to flow.

Maximum AllowableBack Pressure (MABP)

This is the maximum pressure that can exist at the outlet of thedevice (source) without affecting its capacity.

Downstreamtemperature

This temperature is used as the pressure independent temperature atwhich the source enters the network. This temperature is used whenideal gas enthalpies are used to calculate the heat balance, or as aninitial guess when any other enthalpy method is used.

Upstream pressureand temperature

These are only used if Ideal Gas enthalpies are not used for the heatbalance. These may vary for each scenario that you are evaluating.With relief valves, the flowing pressure should be used.

Discharge flange size This will normally be determined from the relief valve sizingcalculations. If this value is unknown then the field should be leftempty to ignore the pressure change from the valve to thedownstream pipe due to the swage.

In this example, you will consider three scenarios that represent one fire case

and two single blocked discharge cases. The following tables define the sourcedata for each scenario.


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1 Getting Started 7

Default Source Data

SourceName

Flowrate(kg/hr)

FlangeSize

(mm)

Mol.Wt.

USTemp

(C)

DSTemp

(C)

USPres.

(barabs)

MABP(bar

abs)

Source 1 100000 300 20 15 15 10 5.0

Source 2 100000 300 25 15 15 10 5.0

Source 1 is a control valve while Source 2 is a relief valve.

Source 1 Only Data

SourceName

Flowrate(kg/hr)

FlangeSize(mm)

Mol.Wt.

USTemp(C)

DSTemp(C)

USPres.(bar

abs)

MABP(barabs)

Source 1 100000 300 20 15 15 10 5.0

Source 2 0 300 25 15 15 10 5.0

Source 2 Only Data

SourceName

Flowrate(kg/hr)

FlangeSize(mm)

Mol.Wt.

USTemp(C)

DSTemp(C)

USPres.(barabs)

MABP(barabs)

Source 1 0 300 20 15 15 10 5.0

Source 2 100000 300 25 15 15 10 5.0

System Design ConstraintsIn this case, the following data is used for both Scenarios:

Maximum allowable mach number - 0.50 for both main headers and

tailpipes.

Maximum allowable noise 100 dB for both main headers and tailpipes.


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1 Getting Started 8

Starting FLARENETThe installation process creates a short-cut to FLARENET in the Start menuunder All Programs...AspenTech. To Start FLARENET,

1 Select the Start menu.

2 Select All Programs-AspenTech-Aspen Engineering Suite-FLARENET2004.1-Aspen FLARENET.

Fig 1.2

Now you are ready to begin working with FLARENET.


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1 Getting Started 9

When you start FLARENET, the FLARENET Desktop will appear:

Fig 1.3

The view in Figure 1.3 has been resized; your Desktop view should appearlarger than this when initially opened. To re-size the view, click and drag

the outside border. To make the view full size, click the Maximiseicon inthe upper right corner.

Before setting up the Getting Startedcase, you should choose theFLARENET unit set for displaying information. You can check your current

unit set by accessing the Preferences Editor:

3 Select File-Preferences and the Preferences Editor view will open.

Fig 1.4


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1 Getting Started 10

4 The current unit set is shown in the Unitsdrop-down list. The FLARENET

default is Metric, which will be used for this example.

Fig 1.5

5 Confirm that the Edit Objects on Addcheckbox is active (checked). This

option will open the object editor view each time a new object is added.

6 Click the OKbutton to close the Preferences Editor view.

Starting A New ModelTo start a new case, do one of the following:

1 Select File-Newon the main program menu bar.

2 Click the New Caseicon.

The Description Editorview appears.

Fig 1.6


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3 Enter the appropriate data (as shown in Figure 1.6) into the User Name,

Job Code, Project, and Descriptionfields, and then click the OKbutton.

The Component Manager view then appears.

Fig 1.7

There are number of ways to select components for your simulation. Onemethod is to filter the database for a certain component type. In this model,

we will be using the following components: Methane, Ethaneand Propane.

To add methane using the filter option:

1 Ensure that the HCcheckbox in the Component Typesgroup is

activated.

2 Start typing methane in the Selection Filterfield. Notice that as you are

typing, the Databaselist will be filtered out to show only the matchingcomponents.

3 Double click Methanein the Databaselist. Methanewill now have beenselected and will be shown in the Selectedlist.

Fig 1.8

The Selectedlist isempty, indicating thatno components haveyet been installed inthe case.

Initially, all thecheckboxes in theComponent Typesgroup are active. Youcan deactivate themby clicking the Invertbutton.


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4 Repeat the previous step with Ethane and Propane. As an alternative

method, you may scroll through the Databaselist until you see thedesired component. Highlight the component by single clicking on it and

then click Add to place it in the Selected Componentslist.

This Component Manager view will now appear as follows:

Fig 1.9

5 Click OKto close the Component Manager view and accept the list of

components.

6 Open the Viewmenu and then the Datasub-menu. Select Componentsfrom the sub-menu. The Components data view will be displayed:

Fig 1.10

Notice that now all therequired componentsare shown in theSelectedComponentslist,indicating that theyhave been installed inthe case.


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Saving The ModelIt is good practice to periodically save your case by doing one of thefollowing:

Click the Saveicon on the toolbar.

Select File-Savefrom the menu bar.

Press Ctrl S.

As this is the first time you have saved your case, the Save FLARENET Modelview will be displayed:

Fig 1.11

After selecting an appropriate disk drive and directory in the Save indrop-

down menu, enter the name of the file to which you want to save the case inthe File namefield.

Note:You do not need to include the .fnw extension; FLARENET will

add it automatically.

Click Saveto close the view and save the file.

You can use thehorizontal scroll barat the bottom ofthe view to view allof the component

properties.


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Building The Pipe NetworkSince all scenarios have a common pipe network, you should first build thepipe network model via the PFD.

Click the Open PFD Viewicon on the toolbar. The PFD view will be displayed

with its own toolbar.

Fig 1.12

At this point the view should be blank, since we have not added a singleobject yet.

The desired objects can be added by using either of the following methods:

Clicking the Toggle Palette Display icon on the PFD view or pressing the

F4 key will open the Toolbox view, which displays all the objects available

in FLARENET. You can add an object by clicking on it

Fig 1.13

Before proceeding anyfurther, make surethat the Edit Objectson Addcheckbox onthe Generaltab ofthe Preferences Editorview is checked.


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Objects can also be added via the Pipe Manager and the Node Managerviews. These are accessible through Pipes...and Nodes...in the Buildmenu, respectively.

For the Flare Tip, click the Flare Tipicon on the Toolbox view. Since the Edit

Objects on Addcheckbox is selected, The Flare Tip Editor view will bedisplayed:

Fig 1.14

By default the Flare Tip has been named as 1, which can be changed to amore appropriate name as follows:

1 Click in the Namefield on the Flare Tip Editorview.

2 Delete the default name and type Flare Tipas the new name.

Since this example is of smaller size, the Locationfield will be left blank.This field is only useful for larger cases with multiple sections (areas)within a same plant. Now you need to specify the pipe, which will be

simulated as a flare stack,and it is attached to the Tip.

3 Enter the name Stackin the Inletfield.

4 In the Atdrop-down list, select Downstreamas the pipe end connectedto the Tip.

In order to complete the Flare Tip Editor view, you need to specify the

Diameterand the Fitting Lossvalues on the Calculationstab.

5 On the Calculationstab, enter 876.3as the diameter and 3as the fitting

loss in the appropriate fields.

The fittings loss

coefficient basisshould be set toTotal Pressure toindicate that theloss coefficient weare defining willcalculate thepressure loss in theflare tip includingthe velocitypressure loss.


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Fig 1.15

Now you have provided all the necessary information about the Tip.6 Click OKto close the view.

Notice that two new objects have been added to the PFD view. These maybe drawn one on top of the other so you should either manually arrange

them by clicking and dragging the object icons or let FLARENET auto-arrange the icons by selecting View-PFD-Regenerate.

7 Open the Stack property view and move to the Dimensionstab.

8 Specify the Lengthas 100m and the Elevation Changeas 100m.

This will result in a vertical pipe measuring 100 m tall.

9 Select the Nominal Diameteras 36 inch and the Pipe Scheduleas 40.

Fig 1.16The default methods,as defined in theCalculation OptionsEditorview, should beIsothermal VaporPressureDrop, andCompressibleGasVLE.


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10On the Methodstab, confirm that Vertical Pipeand VLE Methodare set

as default models.

In this example, every pipe segment uses the default models which are

specified on the Methodstab of the Calculation Options Editor view.

11Click OKto close the Stackproperty view.

Now you need to add another pipe segment which will be added using thePipe Manager view.

12Select Build-Pipes from the menu bar. The Pipe Managerview will be

displayed.

Fig 1.17

13Click the Addbutton.

The Pipe Editorproperty view will be displayed.

Fig 1.18


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14Change the default name to Header 3.

15Move to the Dimensionstab and enter the following data in the

appropriate fields:

Field Value

Length (m) 50

Nominal Diameter (inch) 36

Pipe Schedule 40

16Click OKto close the Pipe Editor view.

17Close the Pipe Manager view by clicking the OKbutton.

You need to attach Header 3with Stackusing a node. FLARENET allows

you to choose between a variety of nodes, since you need a simple

connection between the two pipes, a Connector node will be used.

18On the PFD Toolbox view click on the Connector icon.This will open the Connector Editor view.Fig 1.19

19On the Connectionstab, enter the new name as Con 1.

20In the Downstreamdrop-down list, select Stack and specify theconnection at Upstream(of Stack) in the Atdrop-down list.

21In the Upstreamdrop-down list, select Header 3and specify theconnection at Downstream(of Header 3) in the Atdrop-down list.

22Move to the Calculationstab.

Fig 1.20


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Notice that by default the Thetahas a value of 90deg and the FittingLoss Methodis set as Calculated. These and the other entries may be

left at their default values for this example.

23Click the OKbutton to close the Connector Editor view.

Now, a tee will be added, using the Node Manager, to combine the flow

from the two sources.

24Select Build-Nodes. The Node Managerview will be displayed.

Fig 1.21

25Click the Addbutton and Select Teefrom the pop up list.

The Tee Editor will be displayed.

Fig 1.22


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26Change the default name to Tee 1in the Namefield.

27Specify the Downstreamconnection to be Header 3 and select

Upstream from the Atdrop-down list.

28Move to the Calculationstab and change the Fittings Loss Methodssetting to Millerin the drop-down list. The remaining fields may be left at

their default values.

29Close the Tee Editor property view by clicking the OK button.

30Click OKto close the Node Managerview.Now, you can add two pipe segments to the upstream and branch section

of Tee 1 using the Pipe Manager view.

31Open the Pipe Managerview by selecting Build-Pipes.Fig 1.23

32Click the Addbutton to add a new pipe segment.

33Change the default pipe name to Tail Pipe 1.


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34Specify Tee 1as the Downstreamconnection and select Branchin the

Atdrop-down list

Note:Setting the tailpipe option to Yes will cause the pressure

drop to be calculated using the rated flows rather than theactual flow. For this pipe which is a tail pipe to a control valve

source, the rated flow and actual flow will be the same so thesetting of this option will have no effect.

Fig 1.24

35Move to the Dimensionstab and specify the Lengthas 25m.

36Set Nominal Diameteras 18inch from the drop-down list.

37Click Nextto add another pipe segment.

Notice that Tail Pipe 1has been added to the Pipe Managerlist.

38Change the new pipe segment default name to Tail Pipe 2.

39Specify Tee 1as the Downstreamconnection and select Upstreaminthe Atdrop-down list. Since this pipe is a tail pipe for a relief valve set

the Tailpipeoption to Yes.


41Set Nominal Diameteras 18inch from the drop-down list

Fig 1.25


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42Click the OKbutton to close the Pipe Editor property view.43Close the Pipe Manager view by clicking the OKbutton.

Select Data-Pipesfrom the Viewmenu on the menu bar. The Pipesviewdisplays the data for all of the pipe segments:

Fig 1.26

You could also check the PFD to ensure that the proper connections havebeen made. A portion of the PFD is displayed below:

Fig 1.27

You can also open thePipes view by clickingthe Open PipeTabular Viewicon.


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Defining The ScenariosYou now need to define the data for the entire scenario, the DefaultScenario, Source 1 Only and Source 2 Only scenarios. Since each case

must contain at least one scenario, a set of default scenario data is createdwhen you start a new case. We need to modify this data.

1 Select Scenariosfrom the Buildmenu on the menu bar.

The Scenario Manager view will be displayed.


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Fig 1.28

2 Double click Default Scenarioin the Scenariolist.

Fig 1.29

The Scenario Editor view will be displayed. Alternatively, you could selectDefault Scenarioin the Scenariolist then click Edit.

3 Update the header Mach number limit on the Constraintspage for theDefault Scenarioscenario as shown in Figure 1.30, then click OKtoclose the Edit Scenarioview and return to the Scenario Manager.


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Fig 1.30

Now we should add the data for the Source 1 Only scenario.

4 Click Addon the Scenario Manager. TheClone Scenario Fromview willbe displayed.

Fig 1.31

5 Select the only entry in the view, i.e. Default Scenarioscenario.

6 Change the default name to Source 1 Onlyand enter the data for theSource 1 Onlyscenario as shown in Figure 1.32.


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Fig 1.32

7 To add a new scenario click Nexton the Scenario Editor and select the

Source 1 Onlyscenario from the Clone Scenario Fromview.8 Change the default name for the new scenario to Source 2 Only.

Fig 1.33

9 Enter the data for the new scenario as shown in Figure 1.34.


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Fig 1.34

10Click OKto close the Scenario Editor view and return to the ScenarioManager, then click OKto close the Scenario Manager.

Defining The SourcesYou will now enter the source data for the sources in all scenarios. Since for

the first part of the example you will be defining the source compositions interms of molecular weight, the program preferences must be set to accept

the compositions on this basis.

1 Select Preferencesfrom the Filemenu on the menu bar. The

Preferences view will bedisplayed.Fig 1.35


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Ensure that Mol. Wt.is selected in the Composition Basisdrop-down

list on the Defaultstab.

Fig 1.36

2 Click OKto close the Preferences Editorview.

Before defining a set of source data, you must select the scenario whichcorresponds to this data. You will start by defining the data for the Default

Scenario.

3 Select Default Scenariofrom the drop-down list on the main Tool Bar.

Any open data views would now display data for this scenario. This can

be done using the scenario selector drop-down list on the main FLARENET

toolbar.


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Fig 1.37

You can now add the data corresponding to this scenario for each source.

4 Select Nodesfrom the Buildmenu on the main menu bar (ALT B N). The

Node Manager view will be displayed:

Fig 1.38

5 Click Addand select Control Valvefrom the pop up list.


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Fig 1.39

The Control Valve Editor view will be displayed:

Fig 1.40

6 Change the default name to Source 1. Select Tail Pipe 1in the Outletdrop-down list and set connection to be at Upstream(of Tail Pipe 1).


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Fig 1.41

7 Move to the Conditionstab and set the Mass Flowas 100000kg/hr.In this example, the inlet pressure and temperatures are the same asthe default values but this will not normally be the case.

Fig 1.42

8 On the Compositiontab, specify the Mol. Wt.to be 20. Once you haveentered the Mol. Wt. and tabbed to the next field you will notice thecomposition will be calculated to give the required Mol. Wt.

The Mole Fractions areautomaticallyestimated from theMolecular Weight.Because HC isselected from thedrop-down list, onlyhydrocarboncomponents will beused to match theMolecular Weight.


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Fig 1.43

9 Click Nextto add a new source. The node pop up list will again bedisplayed.

10Select Relief Valvefrom the pop up menu and the Relief Valve view will

be displayed.

11Name the new source asSource 2on the Connectionstab.

12Select Tail Pipe 2in the Outletdrop-down list and set connection to beat Upstream(of Tail Pipe 2).

Fig 1.44

13On the Conditionstab, check that the relief valve set pressure or MAWP

is set to the default value of 10 bar which is correct for this source. Selectthe Autocheckbox next to the Relievingpressure field. This tells

FLARENET to calculate the relieving pressure from the MAWP and theselected Contingency, which should be left as Operatingin this case.

Check that the relieving pressure is calculated as 10.89 bar.


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14Still on the Conditionstab, check that the MABP is set to 5.0bar. Then

enter the required mass flow rate for this source of 100000 kg/ hr. Select

the Autocheckbox next to the Rated flow field. This tells FLARENET tocalculate the rated flow for the valve from the specified fluid conditions

and properties, valve type and orifice area.

15Still on the Conditionstab, use the drop-down list next to the Orificearea field to select orifice code T. Check that the orifice area is updated to

16774 mm2and notice the rated flow calculation is updated to reflect theincreased orifice area.

16On the Compositiontab specify the molecular weight of the fluid to be

25. When you tab away from this field, FLARENET will calculate thecomposition of the fluid from the mole weight. Click back on the

Conditionstab to confirm that the Rated flow calculation has beenupdated to give a rated flow of 109,405 kg/hr.

Fig 1.45

17Click OK to close the Relief Valve Editor view.

The Node Manager view will now appear as follows:

Fig 1.46


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18Close the Node Manager view by clicking the OKbutton.

19Select Data-Sourcesfrom the Viewmenu on the menu bar.

The Sources data view for the Default Scenariowill be displayed:

Fig 1.47

You must now add the source data for the other two scenarios.

20Select the Source 1 Onlyscenario from the Scenario Selector drop-down list on the toolbar (to the right of the icons). Any open data views

will now display data for this scenario.

21Make the following changes to the flowrates in the Source 1 OnlyScenario (all other information remains the same):

Source 1 - 100000 kg/hr

Source 2 - 0 kg/hr

Finally reselect the Default Scenario from the Scenario Selector.

22Next, select the Source 2 Onlyscenario from the Scenario Selectordrop-down list on the tool bar (to the right of the icons) and make the

following changes to the Source 2 Only:

Source 1 - 0 kg/hr

Source 2 - 100000 kg/hr

Finally reselect the Default Scenario from the Scenario Selector.

Rating The NetworkWe have now entered all the model data and can now make the sizing

calculations. We will need to set the calculation options before starting thecalculations.

1 Select Optionsfrom the Calculationmenu on the menu bar. The

Calculation Options Editorview will be displayed:


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Fig 1.48

2 For this example we are going to use the default methods and settings

defined when FLARENET creates a new model. This includes the followingkey options:

On the Generaltab, Calculation Modeshould be set to Rating,Enable heat Transfer checkbox should be cleared, Include Kinetic

Energycheckbox should be cleared.

On the Scenariostab, Calculate should be set to All Scenarios.On the Methodstab, the VLE Methodshould be set to

Compressible Gas, the Enthalpy Methodto Ideal Gasand allpressure drop methods to Isothermal Gas.

You can now start the calculations.

3 Select Calculatefrom the Calculationmenu on the menu bar (ALT C CorCTRL R). Alternatively, you could click the Calculateicon.

Fig 1.49

Once the calculations are complete you can review the results.

4 Select Results-Messagesfrom the Viewmenu on the menu bar.

The Messages data view will be displayed.


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Fig 1.50

The above view contains general information and warning messages

regarding the calculations.

5 Select Source 1 Onlyfrom the Scenario selector.

6 Click Pressure/Flow Summaryicon on the toolbar.

The Pressure/Flow Summaryview will be displayed:

Fig 1.51

With the Pressure/Flow Summary view open, select each scenario in turnusing the Scenarioselector on the toolbar.

Note:In the scenario Source 1 Only, the mach number problemon Tail Pipe 1 is automatically highlighted.

7 At this point save the model using either the Saveicon from the main

Toolbar or the File-Savemenu option.

Printing Data And ResultsTo print data and results:

1 Select File-Print from the menu bar. The Print view will be displayed.

2 Click on the appropriate checkboxes to select the items that you want toprint. Also check the All Scenarioscheckbox to print the results for all of

the scenarios instead of just the current scenario. If you want to print to afile, check the Print To Text Filecheckbox, then select the file type from

the Text File Typedrop-down list.

3 Click OK.

TheProblemstablists two machnumber violations.These problems canbe fixed by doingdesign calculations forthe network but for

this example we willignore the problem.


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2 Developing the Model 37

2 Developing the Model

OverviewIn this Getting Started tutorial you will change the network designed inGetting Started to model the tie-in of two new control valves into our current

system. The modified system will be simulated for two new scenarios, one

each for the new sources.This tutorial assumes that you are familiar with the use of Windows and have

some prior experience in the design of flare systems.

This example consists of the following main parts:

1 Building The Pipe Network -Pipes and nodes will be added using either

the PFD or the Manager views.

2 Defining the Scenarios -Different scenarios will be set up to simulatevarious process conditions.

3 Defining The Sources -Relieving sources will be added to each scenario.

4 Sizing the Network -Finally, the pipe network will be simulated and

results will be viewed both in textual and graphical form.

Data RequirementsBefore you can start to upgrade a computer model of the existing flare header

system, you must first define all the data that will determine your system.

Pipe Segment Data

Data Description

Connectivity You would normally have prepared a system sketch thatdefines the nodes to which the new pipe segments areconnected.

Length and fittings losscoefficients for new pipe segment

These will be based upon either a preliminary or detailedisometric drawing of the piping.

Diameter and pipe schedule foreach pipe segment

If you are rating an existing network, these will normallybe taken from the flare system P&ID. If you are sizing anew flare system, the pipe diameters that you define arerelatively unimportant since they will be overwritten by

This tutorial is acontinuation of theone in Getting Startedand requires that youcomplete that tutorialbefore continuing withthis one.

When you are sizing aflare system, theinitial pipe diametersmay affect thesolution when there isa liquid phase and theliquid knockout drumis modelled. Youshould initially size anetwork using vapourphase methods.


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the sizing algorithms. It is recommended that reasonablediameters be defined, so that the sizing algorithminitialises to a condition that will give faster convergence.

The following diagram shows the connectivity of the system which includesthe new sources you will be adding in this example.

Fig 2.1

The pipe segments in the network diagram are detailed in the following table.

SegmentName

Length (m) NominalDiameter (inch)

Schedule FittingsLoss

ElevationChange (m)

Stack 100 36 40 0 100

Header 1 50 28 30 0 0

Header 2 50 28 30 0 0

Header 3 50 36 40 0 0Tail Pipe 1 25 18 40 0 0

Tail Pipe 2 25 18 40 0 0

Tail Pipe 3 25 12 40 0 0

Tail Pipe 4 25 18 40 0 0

The new pipe segments Header 1, Header 2, Tail Pipe 3 and Tail Pipe 4 will be

added.

Relief Source Data

The following data must be specified for the sources:

Data Description

Flow and Composition These may vary for each scenario that you are evaluating. If arelief source is not used in a particular scenario the flow may beset to zero. The Flow refers to the quantity of fluid that the sourcevalve must pass as a consequence of the plant upset condition. TheRated Flow refers to the quantity of fluid that the source valve willpass due to its physical construction. Rated flow must always be


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greater than or equal to flow.

Maximum AllowableBack Pressure (MABP)

This is the maximum pressure that can exist at the outlet of thedevice (source) without affecting its capacity.

DownstreamTemperature

This temperature is used as the pressure independent temperatureat which the source enters the network. This temperature is usedwhen ideal gas enthalpies are used to calculate the heat balance,or as an initial guess when any other enthalpy method is used.

Upstream Pressure andTemperature

These are only used if the Ideal Gas enthalpies are not used for theheat balance. These may vary for each scenario that you areevaluating. With relief valves, the flowing pressure should be used.

Discharge Flange Size This will normally be determined from the relief valve sizingcalculations.

In this example, you will consider five scenarios that represent one fire case

and four single blocked discharge cases. The following tables define thesource data for each scenario.

The discharge flange size values are left undefined. In this case they areassumed to have the same diameter as the attached pipes

Default Source Data

SourceName

Flowrate(kg/hr)

Mol.Wt.

US Temp(C)

DSTemp(C)

USPres.(barabs)

MABP(barabs)

Source 1 100000 20 15 15 10 5.0

Source 2 100000 25 15 15 10 5.0

Source 3 100000 30 15 15 10 5.0

Source 4 100000 35 15 15 10 5.0

Source 1 Only Data

SourceName

Flowrate(kg/hr)

Mol.Wt.

USTemp(C)

DSTemp(C)

USPres.(barabs)

MABP(barabs)

Source 1 100000 20 15 15 10 5.0

Source 2 0 25 15 15 10 5.0

Source 3 0 30 15 15 10 5.0

Source 4 0 35 15 15 10 5.0

Source 2 Only Data

SourceName

Flowrate(kg/hr)

Mol.Wt.

USTemp(C)

DSTemp(C)

USPres.(barabs)

MABP(barabs)


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Source 1 0 20 15 15 10 5.0

Source 2 100000 25 15 15 10 5.0

Source 3 0 30 15 15 10 5.0

Source 4 0 35 15 15 10 5.0

Source 3 Only Data

SourceName

Flowrate(kg/hr)

Mol.Wt.

USTemp(C)

DSTemp(C)

USPres.(barabs)

MABP(barabs)

Source 1 0 20 15 15 10 5.0

Source 2 0 25 15 15 10 5.0

Source 3 100000 30 15 15 10 5.0

Source 4 0 35 15 15 10 5.0

Source 4 Only Data

SourceName

Flowrate(kg/hr)

Mol.Wt.

USTemp(C)

DSTemp(C)

USPres.(barabs)

MABP(barabs)

Source 1 0 20 15 15 10 5.0

Source 2 0 25 15 15 10 5.0

Source 3 0 30 15 15 10 5.0

Source 4 100000 35 15 15 10 5.0

System Design ConstraintsIn this case, the following data is used for all Scenarios:

Maximum allowable mach number - 0.50 for both main headers and

tailpipes.

Maximum Noise 100 dB for both main headers and tailpipes.

Opening the Old Model1 Start FLARENET and open the previously stored case that you have

just saved in Getting Started.

Select Openfrom the Filemenu on the main program menu bar.

Click the Load An Existing Model From Diskbutton.

Press Ctrl O.

The Open FLARENET Model view will appear.


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Fig 2.2

2 Use the Look indrop-down menu to select the appropriate disk drive and

directory.

3 Next select the file that you created in Getting Started from the list and

click the Openbutton.

Updating the ModelYou need to add new pipe segments to the existing model, but first you mustdelete the connection between Tee 1 and Header 3. Open the PFD and delete

the connection as follows:

1 Click the Toggle Connect/Arrange Modeicon to switch to connectmode and select the connection between Tee 1and Header 3.

Fig 2.3

2 Press the DELETEkey.

To add a tee section after Header 3:

3 Open the Node Manager view, using the Build-Nodesmenu option.


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Fig 2.4

4 Click the Addbutton and select the Teefrom the pop up list.The Tee Editor view will be displayed:

Fig 2.5

5 Specify the name to be Tee 3, the Downstream connection to beHeader 3 and select Upstream from the Atdrop-down list.

6 Move to the Calculationstab and change the Fittings Loss Methods

setting to Millerin the drop-down list.

7 Close the Tee Editorproperty view by clicking OKbutton.

8 Click OK to close the Node Managerview.

Now, you can add two pipe segments to the upstream and branch sectionof Tee 3 using the Pipe Manager view.

9 Open the Pipe Manager view by selecting Pipesfrom the Build menu.

Since this example isof smaller size,therefore theLocationfield will beleft blank. This field isonly useful for larger

case with multiplesections (areas)within a same plant.


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Fig 2.6

10Click the Addbutton to add a new pipe segment.

11Change the default pipe name to Tail Pipe 4.

12Specify Tee 3as the Downstreamconnection and select Branchin theAtdrop-down list.

Fig 2.7


14Set Nominal Diameteras 18inch from the drop-down list.15Click Nextto add another pipe segment.

16Change the new pipe segment default name to Header 2.

17Specify Tee 3as the Downstreamconnection and select Upstreaminthe Atdrop-down list.



After clicking Next,you will notice thatTail Pipe 4has beenadded to the PipeManagerlist.


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Fig 2.8

20Click the OKbutton to close the Pipe Editor property view.

21Close the Pipe Manager view by clicking the OKbutton.

Notice that three new objects have been added to the PFD view. You can

either manually arrange them by clicking and dragging the object icons orlet FLARENET do the auto-arrangement by selecting PFD-Regenerate

from the View menu.

Now you will add a tee section using the PFD Toolbox.

22Open the PFD Toolbox view (if it is not displayed) by clicking the PFDToolboxicon

23Click the Teeicon on the Toolbox view.

Since the Edit Objects on Addcheckbox is selected, The Tee Editor viewwill be displayed.

Fig 2.9


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24Change the default name to Tee 2.

25Specify Header 2as the Downstream connection and select Upstream

in the Atdrop-down list. On the Calculationstab set the fittings loss

method to Miller.

26Close the Tee Editor view by clicking the OKbutton.Now, you can add two pipe segments to the upstream and branch sectionof Tee 2 using the PFD Toolbox view.

27Click the Pipebutton to add a new pipe segment. A fly out menu of 4

buttons showing alternate pipe directions will appear to allow you to selectthe orientation that you require for your PFD. This is only the initial

orientation and it may be changed later.

28On the Pipe Editor view, change the default pipe name to Tail Pipe 3.

29Specify Tee 2as the Downstreamconnection and select Branchin theAtdrop-down list.

Multiple pipe buttonswith differentorientations willappear when this isselected.


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Fig 2.10



32Close the Pipe Editor property view by clicking the OKbutton.33Click the Pipebutton again to add another pipe segment.

34Change the new pipe segment default name to Header 1.

35Specify Tee 2as the Downstreamconnection and select Upstreaminthe Atdrop-down list.

36Specify Tee 1as the Upstreamconnection and select Downstreamin

the Atdrop-down list.37Move to the Dimensionstab and specify the Lengthas 50m.

38Set Nominal Diameteras 28inch from the drop-down list as shown inFig 2.11.


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Fig 2.11

39Click the OKbutton to close the Pipe Editor property view.

Select Data-Pipesfrom the Viewmenu on the menu bar. The Pipes view

displays the data for all of the pipe segments:

Fig 2.12

At this point you might want to rearrange the new items on the PFDmanually or use the View-PFD-Regenerate menu option to redraw the

PFD automatically. The PFD should be similar to that displayed in Figure

2.13:


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Fig 2.13

Defining The ScenariosYou now need to define the data for the new scenarios, the Source 3 Onlyand Source 4 Only scenarios. The existing model already contains three

scenarios which you will still be using in this example. To add the newscenarios:

1 Select Scenariofrom the Buildmenu on the menu bar.

The Scenario Manager view will be displayed.

Fig 2.14

2 Click Addon the Scenario Manager. TheClone Scenario Fromview willbe displayed.


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Fig 2.15

3 Select the Source 2 Onlyscenario from the list.4 Change the default name to Source 3 Onlyand set the Mach number

data in theHeaders and Tailpipes tab to0.5as shown in Figure 2.16.

Fig 2.16

5 To add a new scenario click Nexton the Scenario Editor and select the

Source 3 Only scenario from the Clone Scenario From view.

6 Change the default name for the new scenario to Source 4 Only.


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Fig 2.17

7 Enter the data for the new scenario as shown in Figure 2.16.

8 Click OKto close the Scenario Editor view and return to the Scenario

Manager. Now select Default Scenario and click the Currentbutton tomake this the working scenario. ClickOKto close the Scenario Manager.

Defining The SourcesYou will now enter the source data for the sources in all scenarios. Since for

the first part of the example you will be defining the source compositions in

terms of molecular weight, the program preferences must be set to acceptthe compositions on this basis as described in Getting Started.

1 Select Nodesfrom the Buildmenu on the main menu bar (Alt B S).

The Node Manager view will be displayed:

Fig 2.18

2 Click Addand select Control Valvefrom the pop up list.


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Fig 2.19

The Control Valve Editor view will be displayed:

Fig 2.20

3 Change the default name to Source 3. Select Tail Pipe 3in the Outletdrop-down list and set connection to be at Upstream(of Tail Pipe 3).

4 Move to the Conditionstab and set the Mass Flowas 100000kg/hr.

Fig 2.21


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5 On the Compositiontab, specify the Mol. Wt.to be 30.

Note:The composition will be calculated as soon as you tab awayfrom the Mol Wt field.

Fig 2.22

6 Click Nextto add a new source. The node pop up list will again bedisplayed.

7 Again select Control Valveand the Control Valve Editor view will be

displayed.

8 Name the new source asSource 4.

9 Select Tail Pipe 4in the Outletdrop-down list and set connection to be

at Upstream(of Tail Pipe 4).

Fig 2.23

10Repeat 5-7 to add all the information required by the scenario. SpecifyMole Wt. to be 35on the Compositiontab.

11Click the OKbutton to close the Control Valve Editor view.

The Node Manager view will now appear as follows:

Fig 2.24

The Mole Fractions areautomaticallyestimated from theMolecular Weight.Because HC isselected from thedrop-down list, onlyhydrocarboncomponents will beused to match theMolecular Weight.


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12Close the Node Manager view by clicking the OKbutton.

13Select Data-Sourcesfrom the Viewmenu on the menu bar.

The Sourcesdata view for the Default Scenariowill be displayed:

Fig 2.25

14You must now add the source data for the other four scenarios.

15Select the scenarios from the selector on the tool bar. Any open data

views will display data for the selected scenario.

Make the following changes to the flowrates in all scenarios:

Scenarios Source 1(kg/hr)

Source 2(kg/hr)

Source 3(kg/hr)

Source 4(kg/hr)

Source 1 Only 100000 0 0 0

Source 2 Only 0 100000 0 0

Source 3 Only 0 0 100000 0

Source 4 Only 0 0 0 100000

For each scenario, ensure that the sources which have a flowrate of zero

are ignored(i.e. select the Ignorecheckbox for the source).


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Sizing the NetworkYou have now entered all the model data and can now make the sizingcalculations. You will need to set the calculation options before starting the

calculations.

1 Select Optionsfrom the Calculationmenu on the menu bar. The

Calculation Options Editor view will be displayed:

Fig 2.26

2 For the first calculation of this example ensure that the following options

are set:

On the Generaltab, Calculation Mode should be set to Rating,

Enable Heat Transfer checkbox should be cleared, Include Kinetic

Energy checkbox should be cleared, Ignore Source to PipePressure Loss in Design Mode should be set.

On the Scenarios tab, the Calculate drop-down list should be set toCurrent Scenario.

On the Methods tab, the VLE Method should be set to

Compressible Gas, the Enthalpy Methodto Ideal Gas and all thepressure drop methods to Isothermal Gas.

3 Ensure that the Default Scenariois selected using the ScenarioSelectordrop-down list on the main toolbar.

You can now start the calculations.


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4 Select Calculatefrom the Calculationmenu on the menu bar (ALT C Corctrl r). Alternatively, you could click the Calculationsicon.

Fig 2.27

Once the calculations are complete you can review the results.

5 Select Results-Problemsfrom the Viewmenu on the menu bar. The

Messages data view will be displayed.

Fig 2.28

The above view contains general information and warning messages

regarding the calculations. In this case the mach number exceeds thedesign value of 0.5, which was defined for each scenario, for Tail Pipe 3.

It also shows both upstream and downstream pipe segment mach numberfor each violation. It is due to smaller pipe segments causing very high

fluid velocities across the pipe segment.

At this point, it is a good idea to save your case before doing detaildesign.

6 Select Save Asfrom the Filemenu and save the file as Get Started 2Rating.fnw.

Design Calculations1 We will now use FLARENET's design capabilities to redesign the network to

resolve the mach number problem we have identified in the ratingcalculation we have just completed.

Use the Calculation Mode selector on the main toolbar to change the

calculation mode to Debottleneck. This calculation mode will redesign

the flare system to meet our defined system limits without reducing thecurrent sizes of any pipes.

2 Click the Start Calculationicon on the toolbar.After the calculation has been completed, you can review the new results.


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Fig 2.29

3 Open the Results - Messagesview from the Viewmenu and then select

the Sizingtab to see a list of the changes that FLARENET has made to thenetwork. In this case it has increased the size of Tailpipe 3from 12 inch

to 14 inch.

4 Select Results - Pressure/Flow Summary from the Viewmenu on the

menu bar.


Fig 2.30

Notice that the upstream and downstream mach numbers are now within

the design specification for the given scenario. You can use the bottom

scroll bar to move across the columns.

We now have a flare system that is designed correctly for the Default

Scenariowhere all sources are relieving but we have not yet checkedthat it is adequate for all of the scenarios. To do this we will do a Rating

calculation for all of the scenarios.

5 Open the Calculation Options view and set the Calculation Modeto

Ratingon the Generaltab. On the Scenariostab, set the Calculateoption to All Scenarios. After closing the Calculation Optionsview,

click the Start Calculationicon to run the rating check.

6 When the calculations have finished, open the Results - Messagesviewfrom the Viewmenu. Click on the Problemstab where any violations of

our system design limits will be displayed. You will see that FLARENEThas detected a violation of the mach number limits for the tail pipes in the

single source scenarios.

Fig 2.31

You can also accessthe Pressure/FlowSummary view byclicking the OpenPressure/FlowSummaryicon.


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The reason for this is that the lower back pressure in the system when

only a single source is relieving means that the gas density is reducedresulting in higher velocities.

7 To fix this problem with our design we will re-run the Debottleneck

calculations for all the scenarios. Use the Calculation Modeselector onthe main toolbar to change the calculation mode to Debottleneckand

then click the Calculateicon.

8 When complete, review the Problemstab of the Messages view to

confirm that the flare system now meets all our design limits in all

scenarios. The Sizingtab will show which pipe sizes have beenincreased.

Fig 2.32

Note:We could have run the Debottleneck calculations for all

scenarios immediately after our first rating calculation andobtained the same results. While this might have been faster, we

have obtained a better understanding of which scenarios havecaused changes to pipe sizes by doing our calculations in stages.

9 Select Results-Pressure/Flow Summary from the Viewmenu on themenu bar.


Fig 2.33


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Notice that the upstream and downstream mach numbers are now within

the design specification for the given scenario. You can use the bottom

scroll bar to move across the columns.

10Press Ctrl A to save the case as a new file.

11Enter the new file name as Get Started 2 Design.fnwon the Save

FLARENET Model view and click the Savebutton.


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General Information 59

General Information

This section provides Copyright details and lists any other documentationrelated to this release.

CopyrightVersion Number: 2004.1

April 2005

Copyright 1981 - 2005 Aspen Technology, Inc. All rights reserved.

FLARENET, Aspen Custom Modeler, ACOL, ACX, APLE, AspenAdsim, Aspen Aerotran, Aspen CatRef, Aspen Chromatography, Aspen

Decision Analyzer, Aspen Dynamics, Aspen Enterprise Engineering,Aspen FCC, Aspen Hetran, Aspen Hydrocracker, Aspen Hydrotreater,

Aspen Icarus Process Evaluator, Aspen Icarus Project Manager, Aspen

Kbase, Aspen Plus, Aspen Plus HTRI, Aspen OLI, Aspen OnLine,Aspen PEP Process Library, Aspen Plus BatchFrac, Aspen Plus Optimizer,

Aspen Plus RateFrac, Aspen Plus SPYRO, Aspen Plus TSWEET, AspenSplit, Aspen WebModels, Aspen Pinch, Aspen Properties, Aspen SEM,

Aspen Teams, Aspen Utilities, Aspen Water, Aspen Zyqad,COMThermo, COMThermo TRC Database, DISTIL, DISTIL Complex

Columns Module, FIHR, FRAN, HX-Net, HX-Net Assisted DesignModule, Hyprotech Server, HYSYS, HYSYS Optimizer, ACM Model

Export, HYSYS Amines, HYSYS Crude Module, HYSYS Data Rec,

HYSYS DMC+ Link, HYSYS Dynamics, HYSYS Electrolytes, HYSYSLumper, HYSYS Neural Net, HYSYS Olga Transient, HYSYS OLGAS 3-

Phase, HYSYS OLGAS, HYSYS PIPESIM Link, HYSYS Pipesim Net,

HYSYS PIPESYS, HYSYS RTO, HYSYS Sizing, HYSYS Synetix ReactorModels, HYSYS Tacite, HYSYS Upstream, HYSYS for Ammonia Plants,MUSE, PIPE, Polymers Plus, Process Manuals, Process Tools, ProFES

2P Tran, ProFES 2P Wax, ProFES 3P Tran, ProFES Tranflo, STX,TASC-Thermal, TASC-Mechanical, the aspen leaf logo and Enterprise

Optimization are trademarks or registered trademarks of Aspen Technology,

Inc., Cambridge, MA.

All other brand and product names are trademarks or registered trademarks

of their respective companies.


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General Information 60

This document is intended as a guide to using AspenTech's software. This

documentation contains AspenTech proprietary and confidential information

and may not be disclosed, used, or copied without the prior consent ofAspenTech or as set forth in the applicable license agreement. Users are

solely responsible for the proper use of the software and the application of theresults obtained.

Although AspenTech has tested the software and reviewed the

documentation, the sole warranty for the software may be found in theapplicable license agreement between AspenTech and the user. ASPENTECH

MAKES NO WARRANTY OR REPRESENTATION, EITHER EXPRESSED ORIMPLIED, WITH RESPECT TO THIS DOCUMENTATION, ITS QUALITY,

PERFORMANCE, MERCHANTABILITY, OR FITNESS FOR A PARTICULARPURPOSE.

Corporate

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Phone: (1) (617) 949-1000

Toll Free: (1) (888) 996-7001Fax: (1) (617) 949-1030

URL: http://www.aspentech.com/

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FLARENET Reference Manual Reference Manual for Using FLARENET
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Technical Support 61

Technical Support

Online Technical Support

CenterAspenTech customers with a valid license and software maintenance

agreement can register to access the Online Technical Support Center at:

http://support.aspentech.com

You use the Online Technical Support Center to:

Access current product documentation.

Search for technical tips, solutions, and frequently asked questions

(FAQs).

Search for and download application examples.

Search for and download service packs and product updates.

Submit and track technical issues.

Search for and review known limitations.

Send suggestions.

Registered users can also subscribe to our Technical Supporte-Bulletins. These e-Bulletins proactively alert you to important technical

support information such as:

Technical advisories.

Product updates.

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Product release announcements.
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Phone and E-mailCustomer support is also available by phone, fax, and e-mail for customerswho have a current support contract for their product(s). Toll-free charges are

listed where available; otherwise local and international rates apply.

For the most up-to-date phone listings, please see the Online Technical

Support Center at:

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