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Aspen FLARENET

Getting Started Guide



Version Number: 2006.0

Month: October

Copyright (c) 2006 by Aspen Technology, Inc. All rights reserved.

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iv Contents

Contents1 Introduction.........................................................................................................1

About this document.........................................................................................1 Audience.........................................................................................................1 Related Documentation.....................................................................................1 Technical Support ............................................................................................1

2 Overview..............................................................................................................3

Overview.........................................................................................................3

Data Requirements...........................................................................................4 Pipe Segment Data.................................................................................4 Relief Source Data..................................................................................5 System Design Constraints......................................................................6

Starting FLARENET ...........................................................................................7 Starting a New Model........................................................................................9 Saving the Model ...........................................................................................11 Building the Pipe Network ...............................................................................13 Defining the Scenarios....................................................................................22 Defining the Sources ......................................................................................26 Rating the Network ........................................................................................33 Printing Data and Results ................................................................................35

3 Developing the Model.........................................................................................36

Overview.......................................................................................................36 Data Requirements.........................................................................................36

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

Opening the Old Model.................................................................................... 40 Updating the Model ........................................................................................41 Defining the Scenarios....................................................................................47 Defining the Sources ......................................................................................49

Sizing the Network ...............................................................................53 Design Calculations ........................................................................................55



1 Introduction 1

1 Introduction

This section provides information on the following topics:

About this Document

Audience

Related Documentation

Technical Support

About this documentThe guide provides step by step instructions to the most commonly usedfeatures within FLARENET.

AudienceThis guide is intended for process and process systems engineers.

Related Documentation

Title Content

FLARENET Reference Manual Reference Manual for Using FLARENET

Technical SupportAspenTech customers with a valid license and software maintenanceagreement can register to access the online AspenTech Support Center at:

http://support.aspentech.com

This Web support site allows you to:

Access current product documentation

Search for tech tips, solutions and frequently asked questions (FAQs)

http://support.aspentech.com/



2 1 Introduction

Search for and download application examples

Search for and download service packs and product updates

Submit and track technical issues

Send suggestions

Report product defects

Review lists of known deficiencies and defects

Registered users can also subscribe to our Technical Support e-Bulletins.These e-Bulletins are used to alert users to important technical supportinformation such as:

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Product updates and releases

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2 Overview 3

2 Overview


Overview

Data Requirements

Starting FLARENET

Starting a New Model

Saving the Model

Building the Pipe Network

Defining the Scenario

Defining the Sources

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 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.



4 2 Overview

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 the nodes to which the pipe segments are connected.

Length and fittingsloss coefficients foreach pipe segment

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

Diameter and pipeschedule for eachpipe segment

If you are rating an existing network, these will normally betaken from the flare system P&ID. If you are sizing a newflare system, the pipe diameters that you define are relativelyunimportant since they will be overwritten by the sizingalgorithms. It is recommended that reasonable diameters bedefined, so that the sizing algorithm initializes to a conditionthat will give faster convergence.

The following diagram shows the connectivity of the system that you will bedesigning in this example.

Fig 1.1

When you are

sizing a flaresystem, the initialpipe diameters mayaffect the solutionwhen there is aliquid phase andthe liquid knockoutdrum is modeled.

You should initiallysize a networkusing vapor phasemethods.



2 Overview 5

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 pipe

enlargement and junction losses for the connect to the upstream pipe whichwill automatically be calculated.

Relief Source Data

The following data must be specified for the sources:

Data Description

Flow andComposition

These may vary for each scenario that you are evaluating. If arelief source is not used in a particular scenario the flow maybe set to zero. The Flow refers to the quantity of fluid that thesource valve must pass as a consequence of the plant upsetcondition. The Rated Flow refers to the quantity of fluid thatthe source valve will pass due to its physical construction.

Rated flow must always be greater than or equal to flow.Maximum AllowableBack Pressure(MABP)

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

Downstreamtemperature

This temperature is used as the pressure independenttemperature at which the source enters the network. Thistemperature is used when ideal gas enthalpies are used tocalculate the heat balance, or as an initial guess when anyother enthalpy method is used.

Upstream pressureand temperature

These are only used if Ideal Gas enthalpies are not used forthe heat balance. These may vary for each scenario that youare evaluating. With relief valves, the flowing pressure shouldbe used.

Discharge flangesize

This will normally be determined from the relief valve sizingcalculations. If this value is unknown then the field should beleft empty to ignore the pressure change from the valve tothe downstream 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 source

data for each scenario.



6 2 Overview

Default Source Data

SourceName

Flowrate(kg/hr)

FlangeSize(mm)

Mol.Wt.

USTemp(C)

DSTemp(C)

USPres.(bar

abs)

MABP(barabs)

Source1

100000 300 20 15 15 10 5.0

Source2

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.

(barabs)

MABP(bar

abs)

Source1

100000 300 20 15 15 10 5.0

Source2

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.(bar

abs)

MABP(barabs)

Source1

0 300 20 15 15 10 5.0

Source2

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 andtailpipes.

Maximum allowable noise–

100 dB for both main headers and tailpipes.



2 Overview 7

Starting FLARENETThe installation process creates a short-cut to FLARENET in the Start menu

under Programs...Hyprotech. To Start FLARENET,1 Select the Start menu.

2 Select Programs-Hyprotech-FLARENET 3.51-FLARENET 3.51.

Fig 1.2

3 Now you are ready to begin working with FLARENET.

4 When you start FLARENET, the FLARENET Desktop will appear:



8 2 Overview

Fig 1.3

The view in Figure 1.3 has been resized; your Desktop view should appear

larger than this when initially opened. To re-size the view, click and dragthe outside border. To make the view full size, click the Maximise icon in

the upper right corner.

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

unit set by accessing the Preferences Editor:

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

Fig 1.4

6 The current unit set is shown in the Units drop-down list. The FLARENETdefault is Metric, which will be used for this example.



2 Overview 9

Fig 1.5

7 Confirm that the Edit Objects on Add checkbox is active (checked). Thisoption will open the object editor view each time a new object is added.

8 Click the OK button to close the Preferences Editor view.

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

1 Select File-New on the main program menu bar.

2 Click the New Case icon.

The Description Editor view appears.

Fig 1.6

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

Job Code, Project, and Description fields, and then click the OK button.

The Component Manager view then appears.



10 2 Overview

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 thismodel, we will be using the following components: Methane, Ethane andPropane.

To add methane using the filter option:

1 Ensure that the HC checkbox in the Component Types group is

activated.

2 Start typing methane in the Selection Filter field. Notice that as you

are typing, the Database list will be filtered out to show only thematching components.

3 Double click Methane in the Database list. Methane will now have

been selected and will be shown in the Selected list.

Fig 1.8

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

Initially, all thecheckboxes in theComponent Typesgroup are active.You can deactivatethem by clickingthe Invert button.



2 Overview 11

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

method, you may scroll through the Database list until you see the

desired component. Highlight the component by single clicking on it andthen click Add to place it in the Selected Components list.

This Component Manager view will now appear as follows:

Fig 1.9

5 Click OK to close the Component Manager view and accept the list of

components.

6 Open the View menu and then the Data sub-menu. Select Components

from the sub-menu. The Components data view will be displayed:

Fig 1.10

Saving the ModelIt is good practice to periodically save your case by doing one of the

following:

Click the Save icon on the toolbar.

Select File-Save from the menu bar.

Press Ctrl S.

As this is the first time you have saved your case, the Save FLARENET Model

view will be displayed:

Notice that now allthe requiredcomponents areshown in theSelectedComponents list,

indicating that theyhave been installedin the case.

You can use thehorizontal scrollbar at the bottomof the view toview all of the

componentproperties.



12 2 Overview

Fig 1.11

After selecting an appropriate disk drive and directory in the Save in drop-down menu, enter the name of the file to which you want to save the case inthe File name field.

Note: You do not need to include the .fnw extension; FLARENET willadd it automatically.

Click Save to close the view and save the file.



2 Overview 13

Building the Pipe NetworkSince all scenarios have a common pipe network, you should first build the

pipe network model via the PFD.Click the Open PFD View icon 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 theF4 key will open the Toolbox view, which displays all the objects availablein FLARENET. You can add an object by clicking on it

Fig 1.13

Before proceeding

any further, makesure that the EditObjects on Add

checkbox on theGeneral tab of thePreferences Editorview is checked.



14 2 Overview

Objects can also be added via the Pipe Manager and the Node Manager

views. These are accessible through Pipes... and Nodes... in the Build menu, respectively.

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

Objects on Add checkbox 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 a

more appropriate name as follows:

1 Click in the Name field on the Flare Tip Editor view.

2 Delete the default name and type Flare Tip as the new name.

Since this example is of smaller size, the Location field 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 Stack in the Inlet field.

4 In the At drop-down list, select Downstream as the pipe end connected

to the Tip.

In order to complete the Flare Tip Editor view, you need to specify theDiameter and the Fitting Loss values on the Calculations tab.

5 On the Calculations tab, enter 876.3 as the diameter and 3 as the fittingloss in the appropriate fields.

The fittings loss

coefficient basisshould be set toTotal Pressure toindicate that theloss coefficientwe are definingwill calculate thepressure loss inthe flare tipincluding thevelocity pressureloss.



2 Overview 15

Fig 1.15

Now you have provided all the necessary information about the Tip.6 Click OK to 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 arrangethem 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 Dimensions tab.

8 Specify the Length as 100 m and the Elevation Change as 100 m.

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

9 Select the Nominal Diameter as 36 inch and the Pipe Schedule as 40.

The defaultmethods, asdefined in theCalculation OptionsEditor view, shouldbe IsothermalVapor Pressure Drop, andCompressible Gas VLE.



16 2 Overview

Fig 1.16

10 On the Methods tab, confirm that Vertical Pipe and VLE Method are setas default models.

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

specified on the Methods tab of the Calculation Options Editor view.

11 Click OK to close the Stack property view.

Now you need to add another pipe segment which will be added using the

Pipe Manager view.

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

displayed.Fig 1.17

13 Click the Add button.

The Pipe Editor property view will be displayed.



2 Overview 17

Fig 1.18

14 Change the default name to Header 3.

15 Move to the Dimensions tab and enter the following data in the

appropriate fields:

Field Value

Length (m) 50

Nominal Diameter (inch) 36

Pipe Schedule 40

16 Click OK to close the Pipe Editor view.17 Close the Pipe Manager view by clicking the OK button.

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

you to choose between a variety of nodes, since you need a simpleconnection between the two pipes, a Connector node will be used.

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



18 2 Overview

Fig 1.19

19 On the Connections tab, enter the new name as Con 1.

20 In the Downstream drop-down list, select Stack and specify theconnection at Upstream (of Stack) in the At drop-down list.

21 In the Upstream drop-down list, select Header 3 and specify the

connection at Downstream (of Header 3) in the At drop-down list.22 Move to the Calculations tab.

Fig 1.20

Notice that by default the Theta has a value of 90 deg and the Fitting Loss

Method is set as Calculated. These and the other entries may be left at

their default values for this example.

23 Click the OK button to close the Connector Editor view.

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

from the two sources.

24 Select Build-Nodes. The Node Manager view will be displayed.



2 Overview 19

Fig 1.21

25 Click the Add button and Select Tee from the pop up list.

The Tee Editor will be displayed.

Fig 1.22

26 Change the default name to Tee 1 in the Name field.

27 Specify the Downstream connection to be Header 3 and selectUpstream from the At drop-down list.

28 Move to the Calculations tab and change the Fittings Loss Methods

setting to Miller in the drop-down list. The remaining fields may be left attheir default values.

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

30 Click OK to close the Node Manager view.

Now, you can add two pipe segments to the upstream and branch section of

Tee 1 using the Pipe Manager view.

31 Open the Pipe Manager view by selecting Build-Pipes.



20 2 Overview

Fig 1.23

32 Click the Add button to add a new pipe segment.

33 Change the default pipe name to Tail Pipe 1.

34 Specify Tee 1 as the Downstream connection and select Branch in theAt drop-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 valvesource, the rated flow and actual flow will be the same so the

setting of this option will have no effect.



2 Overview 21

Fig 1.24

35 Move to the Dimensions tab and specify the Length as 25 m.

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

37 Click Next to add another pipe segment.

Notice that Tail Pipe 1 has been added to the Pipe Manager list.

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

39 Specify Tee 1 as the Downstream connection and select Upstream in

the At drop-down list. Since this pipe is a tail pipe for a relief valve setthe Tailpipe option to Yes.


41 Set Nominal Diameter as 18 inch from the drop-down listFig 1.25

42 Click the OK button to close the Pipe Editor property view.



22 2 Overview

43 Close the Pipe Manager view by clicking the OK button.

Select Data-Pipes from the View menu on the menu bar. The Pipes view

displays 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

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 created

when you start a new case. We need to modify this data.1 Select Scenarios from the Build menu on the menu bar.

The Scenario Manager view will be displayed.

You can also openthe Pipes view byclicking the OpenPipe Tabular View icon.



2 Overview 23

Fig 1.28

2 Double click Default Scenario in the Scenario list.

Fig 1.29

3 The Scenario Editor view will be displayed. Alternatively, you could select

Default Scenario in the Scenario list then click Edit.

Update the header Mach number limit on the Constraints page for the4 Default Scenario scenario as shown in Figure 1.30, then click OK to

close the Edit Scenario view and return to the Scenario Manager.



24 2 Overview

Fig 1.30

Now we should add the data for the Source 1 Only scenario.4 Click Add on the Scenario Manager. The Clone Scenario From view will

be displayed.

Fig 1.31

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

6 Change the default name to Source 1 Only and enter the data for the

Source 1 Only scenario as shown in Figure 1.32.



2 Overview 25

Fig 1.32

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

Source 1 Only scenario from the Clone Scenario From view.

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.



26 2 Overview

Fig 1.34

10 Click OK to close the Scenario Editor view and return to the Scenario

Manager, then click OK to 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 Preferences from the File menu on the menu bar. ThePreferences view will be displayed.

Fig 1.35



2 Overview 27

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

list on the Defaults tab.

Fig 1.36

2 Click OK to close the Preferences Editor view.

Before defining a set of source data, you must select the scenario which

corresponds to this data. You will start by defining the data for the DefaultScenario.

3 Select the Default Scenario scenario from the drop-down list on the

main Tool Bar. Any open data views would now display data for thisscenario. This can be done using the scenario selector drop-down list on

the main FLARENET toolbar.



28 2 Overview

Fig 1.37

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

4 Select Nodes from the Build menu on the main menu bar (ALT B N). TheNode Manager view will be displayed:

Fig 1.38

5 Click Add and select Control Valve from the pop up list.



2 Overview 29

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 1 in the Outlet

drop-down list and set connection to be at Upstream (of Tail Pipe 1).



30 2 Overview

Fig 1.41

7 Move to the Conditions tab and set the Mass Flow as 100000 kg/hr. In

this example, the inlet pressure and temperatures are the same as the

default values but this will not normally be the case.

Fig 1.42

8 On the Composition tab, specify the Mol. Wt. to be 20. Once you haveentered the Mol. Wt. and tabbed to the next field you will notice the

composition will be calculated to give the required Mol. Wt.

The Mole Fractions

are automaticallyestimated from theMolecular Weight.Because HC is

selected from thedrop-down list, onlyhydrocarboncomponents will beused to match the

Molecular Weight.



2 Overview 31

Fig 1.43

9 Click Next to add a new source. The node pop up list will again be

displayed.

10 Select Relief Valve from the pop up menu and the Relief Valve view willbe displayed.

11 Name the new source as Source 2 on the Connections tab.

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

Fig 1.44

13 On the Conditions tab, 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 Auto checkbox next to the Relieving pressure field. This tellsFLARENET to calculate the relieving pressure from the MAWP and the

selected Contingency, which should be left as Operating in this case.

Check that the relieving pressure is calculated as 10.89 bar.

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

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

the Auto checkbox next to the Rated flow field. This tells FLARENET to



32 2 Overview

calculate the rated flow for the valve from the specified fluid conditions

and properties, valve type and orifice area.

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

16774 mm2 and notice the rated flow calculation is updated to reflect theincreased orifice area.

16 On the Composition tab specify the molecular weight of the fluid to be25. When you tab away from this field, FLARENET will calculate the

composition of the fluid from the mole weight. Click back on theConditions tab to confirm that the Rated flow calculation has been

updated to give a rated flow of 109,405 kg/hr.

Fig 1.45

17 Click OK to close the Relief Valve Editor view.

The Node Manager view will now appear as follows:

Fig 1.46

18 Close the Node Manager view by clicking the OK button.

19 Select Data-Sources from the View menu on the menu bar.

The Sources data view for the Default Scenario will be displayed:



2 Overview 33

Fig 1.47

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

20 Select the Source 1 Only scenario 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.

21 Make the following changes to the flowrates in the Source 1 Only Scenario (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.

22 Next, select the Source 2 Only scenario from the Scenario Selector drop-down list on the tool bar (to the right of the icons) and make thefollowing 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 sizingcalculations. We will need to set the calculation options before starting the

calculations.

1 Select Options from the Calculation menu on the menu bar. TheCalculation Options Editor view will be displayed:



34 2 Overview

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 following

key options:

On the General tab, Calculation Mode should be set to Rating, Enable

heat Transfer checkbox should be cleared, Include Kinetic Energy checkbox should be cleared.

On the Scenarios tab, Calculate should be set to All Scenarios.

On the Methods tab, the VLE Method should be set to CompressibleGas, the Enthalpy Method to Ideal Gas and all pressure drop methods

to Isothermal Gas.

You can now start the calculations.

3 Select Calculate from the Calculation menu on the menu bar (ALT C C orCTRL R ). Alternatively, you could click the Calculate icon.

Fig 1.49

Once the calculations are complete you can review the results.

4 Select Results-Messages from the View menu on the menu bar.

The Messages data view will be displayed.



2 Overview 35

Fig 1.50

The above view contains general information and warning messagesregarding the calculations.

5 Select Source 1 Only from the Scenario selector.

6 Click Pressure/Flow Summary icon on the toolbar.

The Pressure/Flow Summary view will be displayed:

Fig 1.51

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

Note: In the scenario Source 1 Only, the mach number problem

on Tail Pipe 1 is automatically highlighted.

7 At this point save the model using either the Save icon from the mainToolbar or the File-Save menu 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 to

print. Also check the All Scenarios checkbox to print the results for all of the scenarios instead of just the current scenario. If you want to print to a

file, check the Print To Text File checkbox, then select the file type from

the Text File Type drop-down list.

3 Click OK.

The Problems tablists two machnumber violations.These problems canbe fixed by doingdesign calculations

for the network butfor this example wewill ignore theproblem.



36 3 Developing the Model

3 Developing the Model


Overview

Data Requirements

Opening the Old Model

Updating the Model

Defining the Scenarios

Defining the Sources

Design Calculations

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 currentsystem. 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 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 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.

This tutorial is acontinuation of theone in Getting

Started andrequires that youcomplete thattutorial beforecontinuing with thisone.



3 Developing the Model 37

Pipe Segment Data

Data Description

Connectivity You would normally have prepared a system sketchthat defines the nodes to which the new pipe

segments are connected.Length and fittings losscoefficients for new pipesegment

These will be based upon either a preliminary ordetailed isometric drawing of the piping.

Diameter and pipe schedulefor each pipe segment

If you are rating an existing network, these willnormally be taken from the flare system P&ID. If you are sizing a new flare system, the pipediameters that you define are relativelyunimportant since they will be overwritten by thesizing algorithms. It is recommended thatreasonable diameters be defined, so that the sizingalgorithm initialises to a condition that will givefaster 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 100Header 1 50 28 30 0 0

Header 2 50 28 30 0 0

Header 3 50 36 40 0 0

Tail Pipe1

25 18 40 0 0

Tail Pipe2

25 18 40 0 0

When you aresizing a flaresystem, the initialpipe diameters may

affect the solutionwhen there is aliquid phase andthe liquid knockoutdrum is modelled.You should initiallysize a networkusing vapour phasemethods.




Tail Pipe3

25 12 40 0 0

Tail Pipe4

25 18 40 0 0

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

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

Data Description

Flow andComposition

These may vary for each scenario that you are evaluating.If a relief source is not used in a particular scenario the flowmay be set to zero. The Flow refers to the quantity of fluid

that the source valve must pass as a consequence of theplant upset condition. The Rated Flow refers to the quantityof fluid that the source valve will pass due to its physicalconstruction. 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 the device (source) without affecting its capacity.

DownstreamTemperature

This temperature is used as the pressure independenttemperature at which the source enters the network. Thistemperature is used when ideal gas enthalpies are used to

calculate the heat balance, or as an initial guess when anyother enthalpy method is used.

Upstream Pressureand Temperature

These are only used if the Ideal Gas enthalpies are not usedfor the heat balance. These may vary for each scenario thatyou are evaluating. With relief valves, the flowing pressure

should be used.

Discharge FlangeSize

This will normally be determined from the relief valve sizingcalculations.

In this example, you will consider five scenarios that represent one fire caseand four single blocked discharge cases. The following tables define the

source data for each scenario.

The discharge flange size values are left undefined. In this case they are

assumed to have the same diameter as the attached pipes

Default Source Data

SourceName

Flowrate(kg/hr)

Mol.Wt.

US Temp(C)

DSTemp(C)

USPres.(bar

abs)

MABP(barabs)




Source1

100000 20 15 15 10 5.0

Source2

100000 25 15 15 10 5.0

Source3

100000 30 15 15 10 5.0

Source4

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)

Source1

100000 20 15 15 10 5.0

Source2

0 25 15 15 10 5.0

Source3

0 30 15 15 10 5.0

Source4

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)

Source1

0 20 15 15 10 5.0

Source2

100000 25 15 15 10 5.0

Source3

0 30 15 15 10 5.0

Source4

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)

Source1

0 20 15 15 10 5.0

Source2

0 25 15 15 10 5.0

Source 100000 30 15 15 10 5.0




3

Source4

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)

Source1

0 20 15 15 10 5.0

Source2

0 25 15 15 10 5.0

Source3

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.

2 Select Open from the File menu on the main program menu bar.

3 Click the Load An Existing Model From Disk button.

4 Press Ctrl O.

5 The Open FLARENET Model view will appear.

Fig 2.2




6 Use the Look in drop-down menu to select the appropriate disk drive anddirectory.

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

click the Open button.

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 deletethe connection as follows:

1 Click the Toggle Connect/Arrange Mode icon to switch to connect

mode and select the connection between Tee 1 and Header 3.

Fig 2.3

2 Press the DELETE key.

To add a tee section after Header 3:

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

Fig 2.4




Click the Add button and select the Tee from 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 At drop-down list.

6 Move to the Calculations tab and change the Fittings Loss Methods

setting to Miller in the drop-down list.

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

8 Click OK to close the Node Manager view.

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 Pipes from the Build

menu.

Fig 2.6

10 Click the Add button to add a new pipe segment.

11 Change the default pipe name to Tail Pipe 4.

Since this exampleis of smaller size,therefore theLocation field willbe left blank. Thisfield is only usefulfor larger case withmultiple sections(areas) within asame plant.




12 Specify Tee 3 as the Downstream connection and select Branch in

the At drop-down list.

Fig 2.7



15 Click Next to add another pipe segment.

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





Fig 2.8


21 Close the Pipe Manager view by clicking the OK button.

After clicking Next,you will notice thatTail Pipe 4 has

been added to thePipe Manager list.




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 or

let FLARENET do the auto-arrangement by selecting PFD-Regenerate from the View menu.

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

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

23 Click the Tee icon on the Toolbox view.

Since the Edit Objects on Add checkbox is selected, The Tee Editor view

will be displayed.

Fig 2.9

24 Change the default name to Tee 2.

25 Specify Header 2 as the Downstream connection and select Upstream in the At drop-down list. On the Calculations tab set the fittings lossmethod to Miller.

26 Close the Tee Editor view by clicking the OK button.

Now, you can add two pipe segments to the upstream and branch sectionof Tee 2 using the PFD Toolbox view.

27 Click the Pipe button 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.

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

29 Specify Tee 2 as the Downstream connection and select Branch in theAt drop-down list.

Multiple pipebuttons withdifferentorientations willappear when this isselected.




Fig 2.10



32 Close the Pipe Editor property view by clicking the OK button.

33 Click the Pipe button again to add another pipe segment.

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



36 Specify Tee 1 as the Upstream connection and select Downstream inthe At drop-down list.


38 Set Nominal Diameter as 28 inch from the drop-down list.Fig 2.11





Select Data-Pipes from the View menu 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 thePFD automatically. The PFD should be similar to that displayed in Figure

2.13:

Fig 2.13

Defining the ScenariosYou now need to define the data for the new scenarios, the Source 3 Only

and 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 Scenario from the Build menu on the menu bar.

The Scenario Manager view will be displayed.




Fig 2.14

2 Click Add on the Scenario Manager. The Clone Scenario From view will

be displayed.Fig 2.15

3 Select the Source 2 Only scenario from the list.

4 Change the default name to Source 3 Only and set the Mach numberdata in the Headers and Tailpipes tab to 0.5 as shown in Figure 2.16.




Fig 2.16

5 To add a new scenario click Next on 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.

Fig 2.17

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

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

Manager. Now select Default Scenario and click the Current button tomake this the working scenario. Click OK to 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 acceptthe compositions on this basis as described in Getting Started.

1 Select Nodes from the Build menu on the main menu bar (Alt B S).




The Node Manager view will be displayed:

Fig 2.18

2 Click Add and select Control Valve from the pop up list.

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 3 in the Outlet

drop-down list and set connection to be at Upstream (of Tail Pipe 3).




4 Move to the Conditions tab and set the Mass Flow as 100000 kg/hr.

Fig 2.21

5 On the Composition tab, 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 Next to add a new source. The node pop up list will again bedisplayed.

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

displayed.

8 Name the new source as Source 4.

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

at Upstream (of Tail Pipe 4).

The Mole Fractionsare automaticallyestimated from the

Molecular Weight.Because HC isselected from thedrop-down list, onlyhydrocarbon

components will beused to match theMolecular Weight.




Fig 2.23

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

11 Click the OK button to close the Control Valve Editor view.

The Node Manager view will now appear as follows:

Fig 2.24

12 Close the Node Manager view by clicking the OK button.

13 Select Data-Sources from the View menu on the menu bar.

The Sources data view for the Default Scenario will be displayed:

Fig 2.25

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




15 Select 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 1Only

100000 0 0 0

Source 2Only

0 100000 0 0

Source 3Only

0 0 100000 0

Source 4Only

0 0 0 100000

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

ignored (i.e. select the Ignore checkbox for the source).

Sizing the NetworkYou have now entered all the model data and can now make the sizing

calculations. You will need to set the calculation options before starting the

calculations.

1 Select Options from the Calculation menu on the menu bar. TheCalculation 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 General tab, Calculation Mode should be set to Rating, Enable HeatTransfer checkbox should be cleared, Include Kinetic Energy checkbox

should be cleared, Ignore Source to Pipe Pressure Loss in Design Modeshould 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 Method to Ideal Gas and all the pressure drop methods to

Isothermal Gas.

3 Ensure that the Default Scenario is selected using the ScenarioSelector drop-down list on the main toolbar.

You can now start the calculations.

4 Select Calculate from the Calculation menu on the menu bar (ALT C C orctrl r). Alternatively, you could click the Calculations icon.

Fig 2.27

Once the calculations are complete you can review the results.

5 Select Results-Problems from the View menu on the menu bar. TheMessages data view will be displayed.

Fig 2.28

The above view contains general information and warning messagesregarding the calculations. In this case the mach number exceeds the design

value of 0.5, which was defined for each scenario, for Tail Pipe 3. It alsoshows both upstream and downstream pipe segment mach number for each

violation. It is due to smaller pipe segments causing very high fluid velocitiesacross the pipe segment.

At this point, it is a good idea to save your case before doing detail design.6 Select Save As from the File menu and save the file as Get Started 2

Rating.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 thecalculation mode to Debottleneck. This calculation mode will redesignthe flare system to meet our defined system limits without reducing the

current sizes of any pipes.

2 Click the Start Calculation icon on the toolbar.

After the calculation has been completed, you can review the new results.

Fig 2.29

3 Open the Results - Messages view from the View menu and then select

the Sizing tab to see a list of the changes that FLARENET has made to the

network. In this case it has increased the size of Tailpipe 3 from 12 inchto 14 inch.

4 Select Results - Pressure/Flow Summary from the View menu on

the menu bar.


Fig 2.30

Notice that the upstream and downstream mach numbers are now withinthe 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 DefaultScenario where all sources are relieving but we have not yet checked

that 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 Mode toRating on the General tab. On the Scenarios tab, set the Calculate

option to All Scenarios. After closing the Calculation Options view,

click the Start Calculation icon to run the rating check.

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




6 When the calculations have finished, open the Results - Messages view

from the View menu. Click on the Problems tab 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 thesingle source scenarios.

Fig 2.31

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 reduced resulting 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 Mode selector on

the main toolbar to change the calculation mode to Debottleneck andthen click the Calculate icon.

8 When complete, review the Problems tab of the Messages view to

confirm that the flare system now meets all our design limits in allscenarios. The Sizing tab will show which pipe sizes have beenincreased.

Fig 2.32

Note: We could have run the Debottleneck calculations for allscenarios 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 have

caused changes to pipe sizes by doing our calculations in stages.

9 Select Results-Pressure/Flow Summary from the View menu on the

menu bar.


Fig 2.33



Notice that the upstream and downstream mach numbers are now within thedesign specification for the given scenario. You can use the bottom scroll barto move across the columns.

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

11 Enter the new file name as Get Started 2 Design.fnw on the SaveFLARENET Model view and click the Save button.

aspenflarenet2006-start.pdf

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