COPYRIGHT The copyright in this manual and its accompanying software are the property of Softbits Consultants Ltd with all rights reserved. Both this manual and the software have been provided pursuant to a License Agreement containing restrictions on use. Softbits Consultants Ltd reserves the right to make changes to this manual or its accompanying software without obligation to notify any person or organisation. No part of this manual may be reproduced, transmitted, transcribed, stored in a retrieval system or translated into any other language in any form or by any means, or disclosed to third parties without the prior written consent of Softbits Consultants Ltd.
WARRANTY Softbits Consultants Ltd or its agents will replace any defective manual, program disks within 90 days of purchase of the product providing that proof of purchase is evident. Neither Softbits Consultants Ltd nor its agents or dealers make any warranty, implied or otherwise, with respect to the software or results generated by the software. This program is intended for use by a qualified engineer to aid the design and analysis of flare systems. The results calculated by this program may not be reliable if the input data has not been appropriately specified or if the program is used without regard to its documented limitations. It is the responsibility of the user to interpret the results generated by this program. Softbits Consultants Ltd shall bear no liability for special, indirect, incidental, consequential, exemplary or punitive damages arising from use of this software. The governing law of this warranty shall be that of England.
ACKNOWLEDGEMENTS Softbits Consultants Ltd would like to thank Mr. John F. Straitz III and the National Airoil Company and GBA Ltd of Slough for assistance with some algorithms within the software. Windows XP, Vista and Windows 7 are registered trademarks of Microsoft Corporation. Copyright Softbits Consultants Ltd, 1989, 1990, 2002, 2006, 2008, 2010
Table of Contents 1 Introduction.................................................. 1-1 1.1 1.2 1.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 Program Overview. . . . . . . . . . . . . . . . . . . . . . 1-7 Documentation Overview . . . . . . . . . . . . . . . 1-13
2 Installation.................................................... 2-1 2.1 2.2 2.3 2.4
Installation Requirements . . . . . . . . . . . . . . . . 2-3 Installing Flaresim-Single User . . . . . . . . . . . . 2-4 Installing Flaresim - Network . . . . . . . . . . . . . 2-25 Flaresim File Locations . . . . . . . . . . . . . . . . . 2-40
3 Getting Started............................................. 3-1 3.1 3.2 3.3 3.4 3.5 3.6
Simple Flare Stack Design . . . . . . . . . . . . . . . 3-4 Sonic Tip Design . . . . . . . . . . . . . . . . . . . . . . 3-18 Two Tip Design . . . . . . . . . . . . . . . . . . . . . . . 3-23 Working With Isopleths . . . . . . . . . . . . . . . . . 3-26 Welltest Burner Design . . . . . . . . . . . . . . . . . 3-36 Gas Dispersion . . . . . . . . . . . . . . . . . . . . . . . 3-47
1
2
Introduction
1-1
1 Introduction Page 1.1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2
Program Overview . . . . . . . . . . . . . . . . . . . .7
1.2.1 1.2.2 1.2.3
1.3
Flaresim Objects . . . . . . . . . . . . . . . . . . . . . 7 Object Definition . . . . . . . . . . . . . . . . . . . . . 9 Running a Model . . . . . . . . . . . . . . . . . . . . 10
Documentation Overview . . . . . . . . . . . . . 12
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Introduction
1-3
Flaresim is a computer program designed to assist professional engineers in the design and evaluation of flare systems. The program calculates the thermal radiation and noise generated by flares and estimates the temperatures of exposed surfaces. It also performs dispersion analysis of the combustion gases or relieved fluid in flame out conditions. Flaresim provides a user friendly interface with program actions accessed by menu and toolbar options. Data entry is through a series of data views controlled from an overall Case Navigator view. Context sensitive help is available at all points to assist the user in the use of the program and selection of appropriate design parameters. Output from the Flaresim is highly customisable with the user having the freedom to select summary or detailed output. The reports also include graphical output where appropriate. Experienced flare system engineers should read the remainder of this chapter for an overview of the way that Flaresim performs calculations. They may then find that they will be able to use the program with assistance from the help system without further reference to the manual. However we would advise study of the manual to become familiar with the full range of options and recommendations for using the program. Engineers new to flare system design should work through the examples in the Getting Started section of the manual after first reading this chapter. The examples provide a step by step guide to using Flaresim for flare system design and highlight some of the critical parameters that must be determined.
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Features
1.1 Features The following features highlight the main capabilities of Flaresim. • Equally applicable to the design of flare systems for offshore platforms, gas plants, refineries and chemical plants. • Data may be entered and reported in the users choice of units and may be converted at any time. • Correlations are available for modelling a range of flare tips including sonic tips, pipeflare tips and steam or air assisted tips. For assisted flares the quantity of steam or air required for smokeless operation can be calculated. • A number of correlations are provided to predict the fraction of heat radiated from flames of a range of hydrocarbon fluids with different types of flare tip. • Liquid flaring systems can be handled. • A wide range of algorithms for calculation of thermal radiation. These include integrated multipoint methods and the Chamberlain (Shell) method in addition to the Hajek/Ludwig and Brzustowski/Sommer methods which are described in the API guidelines for flare system design. • Full three dimensional flame shape analysis with complete flexibility in specification of the location and orientation of multiple stacks. • Calculation of combustion gas composition. • Calculation of purge gas flows required for tips. • Jet dispersion model to analyse flammable gas concentrations close to flare in flame out conditions.
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Introduction
1-5
• Gaussian dispersion model to analyse longer distance dispersion of the relieving fluid or combustion gases. • A range of options for defining and analysing the noise spectrum generated by flare systems including user defined spectra. • Ability to define multiple environmental scenarios to allow rapid evaluation of flare system performance under different wind speeds and directions. • Multiple stacks/booms each accomodating multiple flare tips. • Calculation of radiation, noise spectrum and surface temperatures at multiple receptor points. • Calculation of radiation variation with wind direction and speed at a point and display of results on a wind rose chart. • Ability to define multiple receptor grids in multiple planes for calculation of radiation, noise or surface temperatures. • Plotting of grid results as isopleth contours for sterile area definition. • Receptor point characteristics for calculating surface temperatures include mass, absorbtivity, emissivity, area, specific heat, orientation and initial temperature. • Modelling of water curtains or solid shields to reduce radiation and noise transmission. • Sizing of stack or boom length to meet radiation, noise or surface temperature limits at defined receptor points. • A setup wizard to allow new users to set up an initial model rapidly with appropriate defaults.
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Features
• Expert mode to control access to less commonly used options. • Import of files from Flaresim 2.0 and later. • Multiple reports can be created and compared as updates are made to a model and the data corresponding to any report can be saved. • Quality Assurance options are included in the reports. • Customisable HTML reports • Customisable graphic reports • Multiple Flaresim cases can be open at the same time. The wide range of calculation options available within Flaresim may lead to the possibility of selecting inappropriate correlations for a particular combination of fluid type and flare system configuration. While we have tried to prevent the use of the more obvious problems we have also tried to allow flexibility for “one off” situations. As with all engineering computer software, Flaresim is a tool which cannot replace sound engineering judgement. Softbits Consultants Ltd are always interested in continuing product development to ensure that Flaresim meets the needs of our clients. Should you wish to see any feature incorporated in Flaresim, please feel free to contact us at
[email protected]. If the request is reasonable we will endeavour to include it in future releases of the program.
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Introduction
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1.2 Program Overview The Flaresim program has been developed to provide great flexibility in modelling by breaking down the flare system into a number of objects such as fluids, stacks, tips etc. These individual objects are then linked together to define the complete system. Flaresim provides a Case Navigator view, see Figure 1-1, that shows a tree structure of all the objects that have been defined in a given model and provides a rapid overview of which ones are currently complete and in use. Case Navigator Icons
Figure 1-1, Case Summary view
Required object present and ready Required object missing or not ready Optional object Permanent object Object ready Object not ready Object ignored
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Program Overview
1.2.1 Flaresim Objects The objects that can be defined are:Case Summary Each model contains a single Case Summary object which defines descriptive information. Fluids A model can contain multiple fluid objects. Each object describes the physical properties of a fluid to be flared such as density, lower heating value, lower explosive limit etc. Fluids may be defined either by entering bulk properties or by defining the composition of the fluid to allow calculation of its properties from pure component data. A single fluid can be flared through multiple tips. Environments A model can contain multiple environment objects each of which describes a combination of wind speed, direction, humidity etc. The variation of wind speed with direction can also be defined to support wind rose calculations. Environment characteristics can also be defined for use in dispersion calculations. Only one environment object can be active for a set of calculations. Stacks Multiple stack objects can be defined which may be active or ignored in any set of calculations. Stack data includes length, location and orientation. Each stack may support multiple flare tips. Tips Multiple tip objects can be defined and set active or ignored in a set of calculations. Tip data includes tip type and associated calculation methods, dimensions and stack location data and the flow and selection of the fluid being flared. Tip objects provide access to flame shape and other tip specific results such as combustion gas composition and purge gas requirements. Receptor Points Multiple receptor point objects can be defined and then set active or ignored in a set of calculations. Receptor point data includes 1-8
Introduction
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location, characteristics for surface temperature calculation and constraints for sizing calculations. Receptor point objects provide access to results calculated for the point. The effect of wind speed and direction on the radiation can also be calculated and displayed as a wind rose plot. Receptor Grids Multiple receptor grid objects can be defined and then activated or ignored in a set of calculations. Receptor grid data includes orientation, location and coarseness data as well as characteristics for surface temperature calculations. Receptor grid objects provide access to their calculated results including contour plots of radiation, noise, surface temperature and gas dispersion. Assist Fluids Multiple assist fluid objects may be defined and selected for one or more flare tips. Data includes assist fluid type and calculation method to be used. Shields Multiple shield objects may be defined to model the reduction in radiation and noise through the installation of water sprays and solid shields. The transmissivity of water sprays can be specified by the user or calculated using an internal correlation. Shields can also be defined to model burn pits or protective locations. Dispersions Multiple dispersion objects may be defined to model the dispersion of combustion gases and flare fluids over long distances using a Gaussian dispersion model. Either concentration contour plots for a single pollutant or a downwind plot for multiple pollutants can be calculated. Overlays Overlay objects allow simple drawings to be created to act as background pictures for contour plots produced by the Receptor Grid and Dispersion objects.
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Program Overview
Calculation Options A single calculation options object defines the correlations to be used in the calculations. It also provides for control of stack sizing options, heat transfer options to be used for temperature calculations and default emissions data. A data fitting option is also available. Component Management A component library manager object allows maintenance of the pure component database.
1.2.2 Object Definition Flaresim objects are created by selecting the branch in the Case Navigator view and then clicking the Add button. Alternatively the Add dropdown menu in the Case Navigator can be used. Creation of an object automatically opens its view to allow its data to be entered. When all the required data has been entered the status text at the bottom of the view will indicate Ready as shown in Figure 1-2. Some objects have more data items than will fit on a single form so their views have been divided into multiple tabs. For example the Tip view as shown in Figure 1-2 has tabs for Details, Noise Input, Location & Dimensions, Fluids, Emissions, Results, Noise Results, Flame Shape, Combustion Results and Purge Gas. Individual tabs are selected by clicking on their name. Existing objects can be updated by double clicking them in the Case Navigator view or selecting them in the Case Navigator view and clicking the View button. When the Case Navigator is closed existing objects can be displayed by selecting them in the View dropdown menu.
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Introduction
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Figure 1-2, Tip View
1.2.3 Running a Model In order to run calculations a Flaresim model must contain at least one of each of the following objects in an active and ready state. • Fluid object • Environment object • Stack object • Tip object While this is sufficient to perform calculations this will not calculate any radiation, noise or surface temperature results without addition of at least one active Receptor Point or Receptor Grid. Calculations are started by clicking the button at the top of the Case Navigator. This button is also used to display the progress of 1-11
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Program Overview
calculations and the status of the model. When the Case Navigator is closed the icon can be clicked to run the model. Progress of calculations and any problems encountered are reported in the right hand Message window at the bottom of the Flaresim screen. Results from the calculations may be viewed through the appropriate tabs in the Tip view, Receptor Point view or Receptor Grid view. Results may be viewed in tabular or graphical format where appropriate. Alternatively results can be viewed and printed through the Print or Print Graphic Report buttons in the Case Navigator tool bar. Once complete a case can be saved using the Save buttons in the Case Navigator tool bar.
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and Save As
Introduction
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1.3 Documentation Overview The printed Flaresim manual contains the following chapters:Chapter 2 - Software Installation and License Activation. Chapter 3 - Tutorial with detailed worked examples. The electronic documentation in the file Flaresim.pdf contains this material and the following additional chapters which provide a full detailed description of the program features. Chapter 4 - Concepts, Flaresim Interface, Menu structure, Log Panels and File Dialogs. Chapter 5 - General Setup including Case Navigator, Case Summary, Preferences and Component Management. Chapter 6 - Fluid and Assist Fluid views. Chapter 7 - Environment view. Chapter 8 - Stack view. Chapter 9 - Tip view. Chapter 10 - Receptor Point and Receptor Grid views. Chapter 11 - Shield view. Chapter 12 - Dispersion view. Chapter 13 - Overlay editor view. Chapter 14 - Calculation Options view. Chapter 15 - Report options including Print Reports and Graphic Reports. Chapter 16 - Calculation methods. Appendix A - Graphic Report Layout File Definition
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Documentation Overview
Installation
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2 Installation Page 2.1
Installation Requirements . . . . . . . . . . . . . .3
2.1.1 2.1.2
2.2
Installing Flaresim-Single User. . . . . . . . . . 4
2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7
2.3
Starting Flaresim Software Installation . . . 4 Installing .Net Framework . . . . . . . . . . . . . . 5 Running Flaresim Installation. . . . . . . . . . . 7 Installation of Sentinel Drivers . . . . . . . . . 13 Standalone License File Installation . . . . 17 Obtaining A License File . . . . . . . . . . . . . . 19 Troubleshooting Standalone Installation. 22
Installing Flaresim - Network . . . . . . . . . . 25
2.3.1 2.3.2 2.3.3 2.3.4 2.3.5
2.4
Package Requirements . . . . . . . . . . . . . . . . 3 System Requirements . . . . . . . . . . . . . . . . . 3
Installing Server Software . . . . . . . . . . . . . Installing Server License File . . . . . . . . . . Troubleshooting License File Installation Installing Flaresim Clients. . . . . . . . . . . . . Trouble Shooting Flaresim Client. . . . . . .
25 32 36 37 38
Flaresim File Locations . . . . . . . . . . . . . . . 40
2.4.1 2.4.2 2.4.3
Install Locations on Windows XP . . . . . . . 40 Install Locations on Windows Vista . . . . . 41 Install Locations on Windows 7 . . . . . . . . 41
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Installation
2-3
2.1 Installation Requirements 2.1.1 Package Requirements Before installation, check that you have the following elements of the Flaresim package. • Program CD Rom or Flaresim Download Package • USB Computer ID Key, (or legacy 25 pin parallel port key) • License File • Getting Started Guide The License File will be sent to you separately by e-mail as an attachment. You should save the file to a temporary location so that it is ready when required by the installation process.
2.1.2 System Requirements The following system requirements must be met to allow installation of Flaresim. Item Operating system
Requirement Windows XP, Windows Vista or Windows 7
Disk space - Flaresim program
~45 MB
Disk space - .Net framework
~290 MB
Disk space - Sample files (opt) Computer ID key device port Flaresim install files Internet Access
~2MB USB port (opt 25pin parallel port) Supplied on CD Rom or download package For 280 Mb download of .Net framework if not already installed and you are using the Flaresim download package.
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Installing Flaresim-Single User
2.2 Installing Flaresim-Single User The single user version is where usage of the program is controlled by a license file installed on the PC on which Flaresim is running. The installation of Flaresim is a two step process. First the software must be installed. Then the license file must be installed to activate the software.
2.2.1 Starting Flaresim Software Installation The installation of Flaresim is similar to the installation of other Windows programs. The steps are:1.
Shut down other windows programs. The Windows Explorer program may be left open to start the Flaresim Setup program.
2.
Either: Insert the Flaresim CD Rom into your CD or DVD drive. If the AutoRun feature is enabled then step 3 will be performed automatically and should be skipped. Or: Extract install files from download package to a temporary location on your hard disk.
3.
Either: Start the setup program Setup.exe on the CD Rom. This may be done through Windows Explorer by navigating to your CD or DVD drive, locating the Setup.exe file in the root directory of the CD and then double-clicking it. Alternatively you can click the Windows Start button, select the Run option, type d:\setup.exe in the pop-up dialog and then click the Ok button. Note that your CD or DVD drive letter should be substituted if it is not d:. Or: Start the setup program Setup.exe in the temporary location to which you have extracted the installation files.
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Installation
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This may be done through Windows Explorer by navigating to the temporaryfile location, locating the Setup.exe file and then double-clicking it. Alternatively you can click the Windows Start button, select the Run option, type [location}\setup.exe in the pop-up dialog and then click the Ok button. Note [location] is the temporary file location to which you extracted the installation files. The installation program will begin.
2.2.2 Installing .Net Framework Starting with Flaresim version 3.0 the Microsoft .Net Framework 3.5. is required to support Flaresim. The installation program first checks whether this set of support files is available. If it is then the installation process will automatically skip to step 7. If you do not have the .Net Framework already installed on your computer the following screen will be displayed and you will be invited to install it. If you do not install it then the Flaresim installation program will close. The details of the following screen will differ depending on whether you are installing from a CD or a download package. In the former case the .Net Framework 3.5 SP1 files are included on the CD and the screen will appear as shown. In the case of a download package the screen will indicate that the .Net Framework 3.5 SP1 will be installed through download from the web.
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Installing Flaresim-Single User
Figure 2-1, .Net Framework Required
4.
Click the Install button to start the .Net Framework installation. If you are using a Flaresim download package and the Web Download installation of the .Net Framework be aware that this is a 280Mb download and can take an appreciable time to download and install.
5.
Once the .Net Framework installation process has finished the following screen will be displayed. Click the Yes button to restart your computer and complete the installation of the .Net Framework.
Figure 2-2, .Net Framework Installation Finished
6.
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Once your system has completed rebooting please restart the Flaresim Installer as described in section 2.2.1
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2.2.3 Running Flaresim Installation 7.
After verifying the availability of the .Net Framework version 3.5 the Flaresim Installation wizard will start and after a configuration screen for the Windows Installer the follows screen will appear. Click the Next button.
Figure 2-3, Flaresim Installation Wizard Start
Note that the setup program provides a Cancel button that may be clicked to exit the installation procedure at any point. 8.
The following License Agreement screen, Figure 2-4, should then appear..
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Installing Flaresim-Single User
Figure 2-4, License Agreement
9.
At this point you should read the License Agreement and confirm your acceptance of its terms by clicking the accept option. Once the accept option has been selected the Next button will be activated and should be clicked to continue the installation. The following screen, Figure 2-5, will appear. If you do not wish to accept the license terms then click the Cancel button to exit the setup program without installing Flaresim. The license terms must be accepted before the program will install.
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Installation
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Figure 2-5, Destination Folder
10.
If you are content with the proposed installation folder in your Program Files directory then click Next to continue. Otherwise click the Browse button and use the standard windows file browser to select the destination folder for the Flaresim program. Once you are happy with your selection click Next to continue. The installation type screen, Figure 2-6, will appear.
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Installing Flaresim-Single User
Figure 2-6, Installation Type
11.
On this screen for a full installation select the Typical option and click Next. The Custom option should be selected if you do not wish to install the Flaresim sample files. The final install screen will appear..
Figure 2-7, Ready to Install Screen
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Installation
12.
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At this point Flaresim is ready to install. Click the Install button to start the installation process. If you wish to change any data entered in an earlier screen the Back button may be used to return to earlier screens. After clicking the Install button the installation will start.
13.
The setup program will show the progress of the installation as files are copied from the CD Rom to your install folder as shown below.
Figure 2-8, Installation Progress
Should you need to halt the installation, the Cancel button may be used to stop the installation. A confirmation dialog will ask you to confirm that you wish to exit without completing the installation of the program. 14.
Once the installation of the program files has been completed the Flaresim License Installer will be started to allow you to install a local license file.
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Installing Flaresim-Single User
Figure 2-9, Flaresim License Installer
If you do not have your license file or you expect to be using a network license click the Cancel button. Otherwise click the Browse button to open a standard Windows file browser and select the Flaresim license file from the temporary location to which you have saved the license file sent you by email. Alternatively you can type the license file name into the field provided. 15.
When you have entered the license file name, click the Install button. If the license file has been correctly installed the following message will be displayed. Click the Ok button to finish the license installation process and close the license installer.
Figure 2-10, Successfull License Installation
If there is any error in installing the license file a pop-up message will describe the problem and you will be returned 2-12
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to the main window of the Flaresim License Installer. If you have persistent problems then you can use the Cancel button to bypass license installation at this time and complete this later. 16.
Following the closure of the Flaresim License Installer, the following screen will be shown. Click the Finish button to complete the installation process.
Figure 2-11, Completion Screen
2.2.4 Installation of Sentinel Drivers Following completion of the Flaresim installation process an installer for the Sentinel Drivers for use of the Computer ID key will appear as shown below, The Sentinel Drivers are not required for using Flaresim through a network license or for a short term standalone license when the license will be locked to a specific PC hard disk. If this is the case click the Cancel button and skip to section 2.2.5..
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Installing Flaresim-Single User
Figure 2-12, Sentinel Drivers Installation
17.
Click the Next button to start the Sentinel software installation. It is also possible that the Sentinel Protection software is already installed on your PC to support other applications for example, the Aspentech suite. If this is the case you may be offered an Upgrade button in place of the Next button. The Flaresim USB keys are compatible with any version of the Sentinel Protection Installer greater than 7.2.2 so if your current version is more recent you can use the Cancel button to exit without upgrading the Sentinel software.
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18.
A screen displaying the Sentinel Protection software license will then be displayed. This license must be accepted to allow the installation to procede. Click the Next button.
19.
The next screen, Figure 2-13, allows you to select the installation type.
Installation
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Figure 2-13, Sentinel Software Installation Type
For the Flaresim Computer ID keys you need only the driver software so you can select Custom option as shown and click Next to display the Installation Options selection screen shown below, Figure 2-14. Figure 2-14, Sentinel Software Installation Options
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Installing Flaresim-Single User
If you are doing an Upgrade installation you might wish to select the Complete option to ensure that all other Sentinel protected applications will have the required software installed. In this case clicking the Next button will skip to step 23. 20.
In the Sentinel Software Installation Options screen, ensure that the Sentinel System Drivers are selected for installation as shown in Figure 2-14. The other features such as the Sentinel Protection Server can be set to “Do not install”. Click Next to continue.
21.
The next screen will indicate that the Sentinel Protection Installer is ready to begin. Click the Install button to start it.
22.
Once complete the following view, Figure 2-15, will be displayed. Click the Finish button to complete.
Figure 2-15, Sentinel Protection Installer Complete
23.
At this point you are ready to install your Computer ID key. If you have USB computer ID key then plug it into a free USB port on your computer. The first time this is done, you
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should expect to see confirmation that a Sentinel Ultrapro device has been detected and the driver installed. If the key is a parallel port device with 25 pin connectors, plug it into the parallel port of your computer. The parallel port is the 25 pin female connector on the back of your computer. The arrows on the Computer ID key show which end connects to the computer. If you have a printer already connected to the parallel port, disconnect it, connect the key and then reconnect the printer to the female connector on the key. You will not see any messages from the driver software for this type of device. 24.
Congratulations, Flaresim has been successfully installed. You are now ready to run the program for the first time by selecting it through the windows Start menu.
2.2.5 Standalone License File Installation Flaresim requires installation of a license file before it will run. If a license file is not found when Flaresim starts, then an error message similar to that shown below in Figure 2-16 will be displayed. . Figure 2-16, Flaresim License Error
If you are installing a demonstration version of Flaresim or do not have a license file available at installation because this has been emailed separately then you will need to install the Flaresim license using this procedure. If you do not have a license file see the instructions in the following section, 2.2.6, to obtain one. 2-17
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Installing Flaresim-Single User
1.
Firstly ensure that you have permission to write files in the Flaresim program folder - normally C:\Program Files\Flaresim 3.0. This may require Adminstrator or other privileges.
2.
Start the Flaresim License Installer from the Flaresim 3.0 folder in the Start Programs menu. The Flaresim License Installer program will open and display the following view.
Figure 2-17, Flaresim License Installer
2-18
3.
Click the Browse button to open a standard Windows file browser and select the Flaresim license file from either your Flaresim CD or any other location to which you have saved a license file. Alternatively you can type the license file name into the field provided.
4.
When you have entered the license file name, click the Install button. If the license file has been correctly installed the following message will be displayed. Click the Ok
Installation
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button to finish the license installation process and close the license installer. Figure 2-18, Successfull License Installation
If there is any error in installing the license file a pop-up message will describe the problem and you will be returned to the main window of the Flaresim license installer. The most likely cause is that the installer does not have permission to write the license file to the Flaresim program folder. If required you can use the Cancel button to close the Flaresim license installer without installing the license. If you have problems during the license installation or Flaresim continues to generate error messages when you attempt to run it then make a note of any error message messages. You should then follow the troubleshooting guide in section 2.2.7 and/or contact
[email protected] for assistance.
2.2.6 Obtaining A License File If you have a fully licensed copy of Flaresim your license file will normally be emailed to you when you confirm receipt of your Flaresim package. If a license file was not emailed to you, you will need to supply some information about your installation to Softbits Consultants to allow a license file to be generated and emailed to you. The information required will depend on whether you have a full license for the program or a demo license. Full License If you have a full license for Flaresim you will have been supplied with a security key. The security key and its associated license file
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Installing Flaresim-Single User
will allow Flaresim to be used by any PC as long as the security key is installed. The procedure to obtain the license file is as follows: 1. Open the Windows Explorer program and browse to the Support sub-folder in the Flaresim program folder (usually C:\Program Files\Flaresim 3.0\Support). 2.
Locate the program echoid.exe and double click it to run it. The program will check the security key and report the information required through a message window as shown below.
Figure 2-19, Security Key Information
3.
Report this information by e-mail to
[email protected] together with your name and contact details. Your license file will be generated and returned to you by e-mail.
Short Term Lease or Demo License If you have a short term lease or demo license for Flaresim you will not have a security key. A license file will be supplied to activate Flaresim for the single PC on which it is installed and for a limited period. The procedure to obtain the license file is as follows: 1. Open the Windows Explorer program and browse to the Support sub-folder in the Flaresim program folder (usually C:\Program Files\Flaresim 3.0).
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Installation
2.
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Locate the program wechoid.exe and double click it to start it. The program will start and display the screen shown below.
Figure 2-20, Wechoid Program
3.
Clear all the Locking Criteria check boxes except that for Disk ID as shown above. Note the Locking Data displayed at the bottom of the screen. If the Locking Criteria check boxes have been set correctly, the Locking Data selector will be 0x4. Unless otherwise instructed ensure that the radio button at the bottom of the view is set to “New Style” to generate a long 16 character code.
4.
Report the Locking Data by e-mail to
[email protected] together with your name and contact details. Your license file will be generated and sent to you by e-mail. When you receive the license file use the procedure described in section 2.2.5 to install it.
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Installing Flaresim-Single User
2.2.7 Troubleshooting Standalone Installation If an error message similar to Figure 2-16, is seen when starting Flaresim for the first time or an error message is seen when trying to add the Flaresim license then there are two possible causes. • The Computer ID Key is not correctly installed • There is a Sentinel LM server in your network that is responding to license requests and interfering with the operation of the local license for Flaresim. The Sentinel LM system is used by other products apart from Flaresim for example the Aspentech suite of software. Checking Computer ID Key Installation. The first of these problems can be tested for by running the program wechoid.exe which can be found in the support sub-folder of the Flaresim program folder (normally C:\Program Files\Flaresim 3.0). Running this program should give an output similar to that shown in Figure 2-21. If the Computer ID entry is visible and holds a value then the security device is correctly installed If the Computer ID section of the wechoid.exe output is greyed out or no data is shown then the security device is not correctly installed. A possible solution to this problem is to reinstall the Computer ID Key device drivers from the Drivers folder on the Flaresim CD. If the Computer ID key still cannot be seen by wechoid.exe even after reboot then the security device may be faulty and you should contact
[email protected].
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Installation
2-23
Figure 2-21, Wechoid.exe Output
Manual Installation of License File If the license file cannot be installed by the FSWLicense Installer, it is possible to install the Flaresim license file manually as follows. 1. Open Windows Explorer, locate your license file (it will have a .LIC extension) and copy this to the Flaresim program folder (normally C:\Program Files\Flaresim 3.0. 2.
In Windows Explorer, right click the license file in the Flaresim program folder and select the Rename option. Rename the file to “lservrc” note the quotes should be omitted and the file should have no file extension.
Forcing Flaresim to Use a Local License If a Sentinel LM server is present in your network to support the use of other products e.g. the Aspentech suite of software then it is possible that it may be detected by Flaresim when starting and respond to license requests which then fail, preventing Flaresim
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Installing Flaresim-Single User
from starting. In these circumstances Flaresim must be configured to force it to use a local license. There are two methods of doing this:• Create a lshost file to help the Flaresim client locate the server. This is a simple text file called “lshost” containing the word “NO-NET”. A copy of this file can be found in the support subfolder of your Flaresim program folder. To use it simply copy it to the Flareism program folder. Alternatively you can create the file lshost using a text editor. The file must not have a .txt extension and must contain a single line with the word NO-NET. • Set up an environment variable called either LSHOST or LSFORCEHOST and set this to the value NO-NET. Note that environment variables LSHOST and LSFORCEHOST take precedence over the contents of an lshost file (if any). If an LSHOST or LSFORCEHOST environment variable has already been set up to support a different product then it will be necessary to start Flaresim from either a batch file or a script file that resets these variables to values appropriate to for the Flaresim server before starting Flaresim. Examples of both approaches can be found in the files Start Flaresim NoNet.bat and Flaresim NoNet.vbs in the Support sub-folder of the Flaresim program folder. These examples will require update to reflect the precise details of your installation if you have not used the standard installation folders..
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Installation
2-25
2.3 Installing Flaresim - Network The network version of Flaresim allows the use of Flaresim from multiple client systems with the total number of copies in use being controlled by a central Flaresim license server. Installing the Flaresim network version is a 3 step process. Firstly the server software must be installed. Then the license file must be added to the server. Finally the Flaresim client software must be installed on each machine that will run Flaresim. Note the Flaresim license server is any PC on which the server software is installed. It does not have to be an existing network file server IMPORTANT NOTE If you already have a Sentinel LM server version 7.2 installed for a version of Flaresim prior to 2.1 it must be uninstalled and replaced with the new Sentinel RMS version 8 server that ships with Flaresim 3.0.
2.3.1 Installing Server Software The Flaresim server software is the Sentinel RMS product from Safenet Inc. Full details of this product are given in the online manuals which can be found in the SysAdminHelp sub-folder of the Server folder of the Flaresim CD. The following instructions are provided as a quick guide to installing your server software with a basic configuration. For more detailed information on the management of Sentinel RMS servers consult the online manuals. The installation of the server software is similar to the installation of other Windows programs. The steps are:1. Shut down other windows programs. The Windows Explorer program may be left open to start the server setup program if required. 2-25
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Installing Flaresim - Network
2.
Insert the Flaresim CD Rom into your CD or DVD drive. If the AutoRun feature is enabled then the screen shown below will appear inviting you to start a client installation. If this happens click the Cancel button to exit the client installation.
Figure 2-22, Flaresim Client Screen
3.
Open Windows Explorer, select the Flaresim install CD and browse to the folder \Server\Setup. Double click on the program Setup.exe to run it. Alternatively you can click the Start button select Run and then type [Drive]:\Server\Setup\Setup.exe where [Drive] is the drive letter of your CD. Hit Enter to start the setup program. On starting the server setup program the following screen will appear
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Installation
2-27
Figure 2-23, Server Setup Opening Screen
4.
Click the Next button to continue. The following license agreement screen will be displayed
Figure 2-24, Server Setup License Agreement
5.
Click the appropriate radio button to accept the server software license agreement and click Next to continue. You must accept the license agreement in order to be able to run the Flaresim server software. 2-27
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Installing Flaresim - Network
The following screen will then appear. Figure 2-25, User Selection
6.
This screen defines whether the software will be installed for all users of this computer or only the current user. Generally you will want to install it for all users. Once you have made your selection click Next to continue. The following screen will be shown.
Figure 2-26, Server Software location
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Installation
7.
2-29
This screen defines the location to which the server software will be installed, click Next to continue. The following screen will be displayed.
Figure 2-27, Select Installation Options
8.
This screen allows selection of the Installation Options. Since Flaresim licenses are locked to Computer ID keys you must select the Complete option to install the device drivers for the keys as well as the server software. Click Next button to continue. The following view will be displayed.
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Installing Flaresim - Network
Figure 2-28, Firewall Settings
9.
A port must be opened through any server firewall to allow communication between the Flaresim server and client PCs. This screen allows you to tell the installer to do this automatically. Note that if you are using 3rd Party firewall software you may need to do this separately. The system administrators help system has the information you need to do this (Server\SysAdminHelp folder on CD). Select the check box and click Next. The following screen will be displayed.
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Installation
2-31
Figure 2-29, Ready to Install
10.
This confirms that you are ready to begin installation of the Sentinel RMS server software. Click the Install button. The server software install process will then start. On completion the following screen will be displayed.
Figure 2-30, Server Installation Complete
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Installing Flaresim - Network
11.
At this point the server software is installed and the server service will have been started. Click the Finish button to close the window.
12.
You may wish to confirm that the server service has installed correctly by checking the list of running processes through the Task Manager. The server service is called lservnt.exe. By default, this service will be set to start automatically each time the computer is started.
13.
Optionally copy the server utility programs to your server as follows. Open Windows Explorer and browse to the directory [Drive]:\Server\Admin.net\W32 where [Drive] is the drive letter of your CD drive. Select and copy all the files from this directory to an appropriate place on your server. It is up to your local policies whether to make these file available to Flaresim users as well as server administrators.
2.3.2 Installing Server License File The Flaresim server software requires installation of a license file before it will be able to authorise Flaresim client software to run. This license file will normally be locked to the Computer ID key supplied with Flaresim. The procedure to install the Computer ID key and license file is as follows. The license file will normally be found on the Flaresim CD. 1. Locate and install your Computer ID key on your server system. If you have USB computer ID key then plug it into a free USB port on your computer.
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Installation
2-33
If the key is a parallel port device with 25 pin connectors, plug it into the parallel port of your server. The parallel port is the 25 pin female connector on the back of your computer. The arrows on the Computer ID key show which end connects to the computer. If already have a printer on the parallel port, disconnect it, connect the key and then reconnect the printer to the female connector on the key. 2.
Open Windows Explorer and use it to browse to and start the program WlmAdmin.exe from either the Flaresim CD or the location to which you copied the server utility software. When open, the program will display the following screen.
Figure 2-31, WlmAdmin Program
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Installing Flaresim - Network
3.
Expand the tree of SubNet servers by clicking the symbol next to the SubNet servers entry. If your system is the only Sentinel server on the network then you will see only its name in the list. If other servers are present locate the server to which you have connected the Flaresim security device.
4.
Right click the name of your server in the SubNet server list. From the pop-up menus select Add Feature, From a File, To Server and its File as the options appear as shown below.
Figure 2-32, WlmAdmin - Adding license
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Installation
5.
Left click on the To Server and its File option. Select your license file (.lic extension) in the browser and click Open. Your license should be added to the server and displayed in the tree below the server name.
6.
You will now be able to click the Flaresim license to display its details as shown below. Note that the WlmAdmin program can be used to show usage details of licenses at any time.
2-35
Figure 2-33, WlmAdmin License details
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Installing Flaresim - Network
2.3.3 Troubleshooting License File Installation Should you get an error message when installing the license file perhaps of the form shown below then the first thing to check is that the Computer ID key is plugged in and accessible. Figure 2-34, License Installation Error
This can be done by running the program wechoid.exe which can be found in the folder Server\Admin.net\W32 on your Flaresim CD. Running this program should give an output similar to that shown below. If the Computer ID entry is visible and holds a value then the security device is correctly installed. Figure 2-35, Wechid.exe Output
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Installation
2-37
If the Computer ID section of the wechoid.exe output is greyed out or no data is shown then the security device is not correctly installed. A possible solution to this problem is to reinstall the security device drivers from the Drivers folder on the Flaresim CD. If the security device still cannot be seen by wechoid.exe even after reboot then the security device may be faulty and you should contact
[email protected] If the license file will not install when the wechoid.exe output shows that the security device is visible then there may be a problem with the license file and you should contact
[email protected].
2.3.4 Installing Flaresim Clients The installation of the Flaresim client software for use with a Flaresim license server is the same as for a standalone installation as described in sections 2.1.1 to 2.2.3 above. Since there is no requirement for local license in a Flaresim network installation, when the FSWLicense installer is shown, step 14. , Figure 2-9, you should click the Cancel button. Likewise since there is no need for a security key on a Flaresim client in a network installation you should click Cancel when the Sentinel Protection Installer view is displayed, step17., Figure 2-12. You are now ready to run the Flaresim by selecting it through the windows Start menu.
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Installing Flaresim - Network
2.3.5 Trouble Shooting Flaresim Client If the Flaresim client program fails to find a server license when it starts up the following message will be displayed. Figure 2-36, License Error
If you see this message you should click the Ok button to close the window. The following check list offers possible reasons why Flaresim might not be able to locate the license server to obtain a license. • All available licenses are in use. • Client system does not have network access to the server. • Server may not be active. Checking Available Licenses The first step in resolving these problems is to run the WlmAdmin program from the client system and open the list of subnet servers. If the Flaresim server can be seen, open the Flaresim license to check whether there is a license available. If all are in use the client must wait until a license becomes free. It can take up to 5 minutes for a license to become free after another user has shut down Flaresim. Configuring Server Location If an available license can be seen on the server but the Flaresim client still will not load then it may be caused by Flaresim being either unable to locate the Flaresim server or by Flaresim locating another Sentinel server for another product e.g. Aspentech products.
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Installation
2-39
In this case it is necessary to specify the name of the host to Flaresim. There are two options for this:• Create a lshost file to help the Flaresim client locate the server. To do this create a simple text file called lshost (note no .txt extension) in the Flaresim client program directory. Edit the contents of this file so that it contains the name of the Flaresim server. For example in the case of the server installation shown in section 2.3.2 of this file would have the text “orac.flaresim.co.uk”. • Set up an environment variable called either LSHOST or LSFORCEHOST to specify the name of the server. For example in our example the environment variable would be set LSHOST=orac.flaresim.co.uk • If multiple servers must be included in a lshost file or LSHOST variable use a “~” character to separate the e.g. “server1.flaresim.co.uk~server2.flaresim.co.uk Note that environment variables LSHOST and LSFORCEHOST take precedence over the contents of an lshost file (if any). If an LSHOST or LSFORCEHOST environment variable has already been set up to support a different product then it will be necessary to start Flaresim from either a batch file or a script file that resets these variables to values appropriate to for the Flaresim server before starting Flaresim. Examples of both approaches can be found in the files Start Flaresim.bat and Flaresim.vbs in the Support sub-folder of the Flaresim program folder. These examples will require update to reflect the precise details of your installation. Checking Access To The Server If the WlmAdmin program does not list a Flaresim server when run on the client then the problem likely lies in the client system not having network access to the server. You will need to check all elements of the network routing (e.g. firewalls, routers) to ensure that the server can be seen by the client system. Further help on license server setup and possible problems can be found in the online manual in the SysAdminHelp folder on the Flaresim CD. 2-39
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Flaresim File Locations
2.4 Flaresim File Locations A Flaresim client installation comprises a number of files split into the following groups. Program Files Program - Flaresim.exe Support libraries - various .dll files License installer - FSWLicense.exe Installed license file - lservrc Help files - FSWHelp.chm, *.HLP Documentation folder - Flaresim.pdf Support Files Layout files - *.lay Default case file - Default.fsw Default report definition - Flaresim.xsl Units definitions - Units.xml Component database - LibraryComponents.xml Default preference file - Preferences.xml Default preferences file - PrintPreference.xml Report logo file - Logo.gif Sample Files Examples - *.fsw Report sub-folders
2.4.1 Install Locations on Windows XP The default install locations for the different groups of files when Flaresim is installed on Windows XP are as follows. Program Files C:\Program Files\Flaresim 3.0 Support Files C:\Documents and Settings\All Users\Application Data\Softbits\Flaresim 3.0 Sample Files [My Documents]\Softbits\Flaresim 3.0\Samples
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2.4.2 Install Locations on Windows Vista The default install locations for the different groups of files when Flaresim is installed on Windows Vista are as follows. Program Files C:\Program Files\Flaresim 3.0 Support Files C:\ProgramData\Softbits\Flaresim 3.0 Sample Files [My Documents]\Softbits\Flaresim 3.0\Samples
2.4.3 Install Locations on Windows 7 The default install locations for the different groups of files when Flaresim is installed on Windows 7 are as follows. Program Files C:\Program Files\Flaresim 3.0 Support Files C:\ProgramData\Softbits\Flaresim 3.0 Sample Files [My Documents]\Softbits\Flaresim 3.0\Samples
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Flaresim File Locations
Getting Started
3-1
3 Getting Started Page 3.1
Simple Flare Stack Design . . . . . . . . . . . . .4
3.1.1 3.1.2 3.1.3 3.1.4
3.2
Sonic Tip Design . . . . . . . . . . . . . . . . . . . . 18
3.2.1 3.2.2 3.2.3 3.2.4 3.2.5
3.3
18 18 18 20 21
Objective and Data. . . . . . . . . . . . . . . . . . . Open Starting File . . . . . . . . . . . . . . . . . . . Update Tip Data . . . . . . . . . . . . . . . . . . . . . Run & Review Calculations. . . . . . . . . . . . Update Pipe Tip . . . . . . . . . . . . . . . . . . . . .
23 23 24 24 25
Working With Isopleths . . . . . . . . . . . . . . . 26
3.4.1 3.4.2 3.4.3
3.5
Objective and Data. . . . . . . . . . . . . . . . . . . Open Starting File . . . . . . . . . . . . . . . . . . . Create Sonic Tip. . . . . . . . . . . . . . . . . . . . . Run & Review Calculations. . . . . . . . . . . . Compare Results . . . . . . . . . . . . . . . . . . . .
Two Tip Design . . . . . . . . . . . . . . . . . . . . . . 23
3.3.1 3.3.2 3.3.3 3.3.4 3.3.5
3.4
Objective and Data. . . . . . . . . . . . . . . . . . . . 4 Initial Setup. . . . . . . . . . . . . . . . . . . . . . . . . . 4 Initial Calculations . . . . . . . . . . . . . . . . . . . 13 Print Results . . . . . . . . . . . . . . . . . . . . . . . . 16
Open Starting File . . . . . . . . . . . . . . . . . . . 26 Adding a Flaresim Overlay . . . . . . . . . . . . 30 External Overlay File . . . . . . . . . . . . . . . . . 33
Welltest Burner Design . . . . . . . . . . . . . . . 36 3-1
3-2
3.5.1 3.5.2 3.5.3 3.5.4 3.5.5 3.5.6 3.5.7 3.5.8 3.5.9 3.5.10
3.6
Gas Dispersion. . . . . . . . . . . . . . . . . . . . . . 47
3.6.1 3.6.2 3.6.3 3.6.4 3.6.5 3.6.6
3-2
Objective and Data. . . . . . . . . . . . . . . . . . . .36 Open Starting File . . . . . . . . . . . . . . . . . . . .36 Add New Fluid Data . . . . . . . . . . . . . . . . . . .36 Add New Stack . . . . . . . . . . . . . . . . . . . . . . .37 Add Welltest Burner Tip . . . . . . . . . . . . . . .39 Add New Receptor Point . . . . . . . . . . . . . . .39 Run & Review Calculations. . . . . . . . . . . . .40 Add Water Screen . . . . . . . . . . . . . . . . . . . .41 Evaluate Rate of Temperature Rise . . . . . .44 Check Safety Case. . . . . . . . . . . . . . . . . . . .45
Objective and Data. . . . . . . . . . . . . . . . . . . .47 Load or Create Base Case . . . . . . . . . . . . .48 Jet Dispersion Calculation . . . . . . . . . . . . .48 Gaussian Dispersion, Contour Plot . . . . . .51 Gaussian Dispersion, Downwind Plot . . . .53 Dispersion Analysis Comments . . . . . . . . .56
Getting Started
3-3
The purpose of this chapter is to provide an introduction to the use of Flaresim. The examples show how Flaresim may be used to calculate thermal radiation, noise and exposed surfaces temperatures arising from flaring at one or more flare stacks. Examples of dispersion calculations are also given. The examples begin with a simple flare stack design which is then refined and expanded. The examples attempt to highlight some of the critical parameters to be considered when designing a safe flare system. The examples build up in stages. If you wish to skip a particular stage, the Samples sub-folder of the Flaresim program folder has model files saved at each stage.
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Simple Flare Stack Design
3.1 Simple Flare Stack Design 3.1.1 Objective and Data The objective is to design a flare stack for an offshore platform. It is assumed that an inclined flare boom will be used mounted on the side of the platform which faces the prevailing wind. The design is to be based on thermal radiation limits as follows:• 1,500 btu/hr/ft2 at the base of the flare stack. • 600 btu/hr/ft2 at the helideck located 150 ft from the side of the platform and 30 ft above the base of the flare stack. The following design data is available Fluid Material Hydrocarbon Vapour Flow 100,000 lb/hr Mol Wt. 46.1 Vapour Temp. 300 F Heat of combustion 21,500 btu/lb Heat Capacity ratio 1.1 Tip Diameter
18 in
Wind Velocity
20 mph
3.1.2 Initial Setup
New File Icon
3-4
1.
Start the Flaresim program through the windows Start button in the usual way.
2.
We are going to build our first model through the Setup Wizard. For a new installation of Flaresim this will open automatically ready to build a new model. If this does not appear then you should select the File - Preferences menu option and select the “Use Setup Wizard for New Cases” check box on the Files&Options tab. Then select File - New
Getting Started
3-5
or the New File icon on the tool bar to create a new case with the Setup Wizard. 3.
In the opening view of the Setup Wizard, set the unit set to Default Field as shown. Then click the Next button to move to the Fluid definition tab.
Figure 3-1, Setup Wizard Opening View
4.
In the Fluid tab of the Setup Wizard enter the following data items, using the tab key or the mouse to move from field to field. Temperature = 300 F Mole Weight = 46.1 LHV = 21500 btu/lb Cp/Cv = 1.1 Note that some of these values (e.g Temperature or Cp/Cv) are originally displayed in purple colour denoting a default 3-5
3-6
Simple Flare Stack Design
LEL is used only by the Brzustowski flare radiation method.
value. When you entered a value the colour changes to blue denoting a user specified value. The full list of colours used by Flaresim to display values is:Purple for a fixed default value Red for calculated default values Blue for a user specified value Grey for a fixed, unchangeable input value Black for a calculated result The remaining values for Ref Pressure, LEL and Saturation can be left at their default values. The finished view is shown below Figure 3-2, Setup Wizard Fluid Tab
Note that Flaresim requires the lower heating value for a fluid for its calculations. We are assuming that the value we 3-6
Getting Started
3-7
have been given is the lower, net heating value rather than the higher, gross heating value. Advice on the usage of each input value and the allowable input range is displayed in the advice panel as you move through the input fields. When the entries are complete click the Next button. 5.
In the Tip tab select the radio button to set the tip type to a Pipe Tip. In the table for selection of F Factor method select the check box to select the Generic Pipe method. The F Factor, i.e. the fraction of heat radiated by the flame, is a critical design parameter for flare system design. The Generic Pipe correlation has been developed to predict F Factors across a range of exit velocities and fluid molecular weights and is generally recommended for initial calculations. For final designs, we would always recommend consulting a flare system vendor for advice on the appropriate F Factor for a specific fluid and specific flare tip.
6.
Still in the Tip tab, enter the Fluid Mass Flow Rate as 100,000 lb/hr. After this entry has been completed, the Tip Diameter field is updated to show the tip diameter required for the default Mach number of 0.45. In our case we know the tip diameter is 18 in so we update the calculated value to 18 in. The Mach number will be updated to 0.199 to indicate the velocity for the new diameter. When complete the view should be as shown in Figure 3-3.
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Simple Flare Stack Design
Figure 3-3, Setup Wizard Tip Tab
Click the Next button to move to the next tab. 7.
The humidity value is only used when calculating the transmissivity.
3-8
In the next tab, the Environment tab, enter the wind speed. Since the value we have been given is 20 mph we first click the entry displaying ft/s and select mph in the drop down menu before entering the value. If we wish to see the value in ft/s then click again in the units entry and select ft/s to display the converted value of 29.33 ft/s. The remaining items can be left at their default values namely Wind Direction as 0 (i.e. North), Temperature 59 F, Humidity 10% and the User Transmissivity 1.0 with the Transmissivity Method set to “User specified”. Note this default transmissivity method with a specified transmissivity value of 1.0 is the most conservative option.
Getting Started
3-9
The final input is to remove the tick from the check box labelled “Include Solar Radiation” which means that the specified solar radiation value will NOT be added to the calculated value of flare radiation. Including solar radiation leads to a more conservative design and its inclusion is recommended by API 521. However some sources suggest it can be excluded. Solar radiation can have a significant impact on the flare design when low radiation values are considered. Since we considering a low design radiation for the Helideck in this case we will exclude solar radiation for this example. The completed view is shown as Figure 3-4. Click the Next button to continue. Figure 3-4, Setup Wizard Environment Tab
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Simple Flare Stack Design
8.
In the Stack tab, select the radio button to set the Vertical Orientation to 60 degrees from horizontal. Then set the Stack Horizontal Orientation angle to 0 (i.e. North). The Stack Length will be left unspecified to let Flaresim calculate it. The completed form is shown as Figure 3-5. Click the Next button to continue.
Figure 3-5, Setup Wizard Stack Tab
9.
In the Receptors tab, click on the default receptor point “RP_1” and rename it to “Stack Base”. Set its Distance Downwind from Stack to 0 ft and confirm that the Allowable Radiation for the point is 1500 btu/hr/ft2. Now click the Add button to create an additional receptor point for the radiation at the Helideck. Change the default name “RP_2” to “Helideck” and enter the location as North-
3-10
Getting Started
3-11
ing -150ft, Easting 0ft, Elevation 30ft. and the radiation limit as 600 btu/hr/ft2. The completed form is shown as Figure 3-6. Click the Next button to continue. Figure 3-6, Setup Wizard Receptors Tab
10.
In the Calculations tab, select the check box to set the Calculation Method to Mixed and set the Flame Elements to 25. As discussed in the Methods chapter, the Mixed method is a compromise designed to give the best accuracy for calculating radiation both close to and further away from the flame. As such it is a good default method. 25 flame elements is usually sufficient to calculate the flame shape with a reasonable degree of accuracy.
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Simple Flare Stack Design
The completed view is shown as Figure 3-7. At this points we have completed the Setup Wizard so click the Finish button. Figure 3-7, Setup Wizard Calculations Tab
11.
3-12
When the Finish button is clicked, the Setup Wizard takes the data we have supplied and uses it to create the Flaresim objects that we need for our initial model. The Case Navigator view will be displayed to list all of these objects as shown in Figure 3-8. Note that the icon is shown against each object indicating it is ready to calculate and that the icon is shown against the key object branches to indicate that the model has the minimum information needed to run calculations.
Getting Started
3-13
At this point you can open each objects view by double clicking on them in the Case Navigator to see how the Setup Wizard has initialised the values. Figure 3-8, Case Summary
12.
This is a suitable point to save the data we have entered so far. Click the tool bar button in the tool bar at the top of the Case Navigator or main tool bar. Since we have not yet saved the file, a File Save Dialog window will appear to allow us to specify the location and name of the file.
3.1.3 Initial Calculations 13.
At this point we are ready to run the calculations by clicking the large button labelled “Click to Calculate” at the top of the Case Navigator. The button will change to show a progress bar as the calculation runs. Messages will be output to the Error/Warnings/Info log to show progress as shown below.
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Simple Flare Stack Design
Figure 3-9, Error/Warnings/Info log
Note that the scroll bars can be used to review earlier messages. Also the log window can be resized by dragging the separator bar above it. 14.
We can now review the results. Double click the Grid 1 item in the Case Summary view and then click the Radiation tab. Then select Plot in the Display drop down. The radiation isopleths are displayed as shown below.
Figure 3-10, Receptor Grid Isopleth Plot
3-14
Getting Started
3-15
Click Stack 1 in the Case Navigator view and click the View button. The view will show that the stack length has been calculated as 247ft. Finally open the Receptor summary view by double clicking the “Receptor Point” branch label in the Case Navigator. As shown below, the Radiation Results line shows that our design radiation limit of 600 btu/h/ft2 has been met for the Helideck receptor while the radiation value at the Stack Base receptor is lower than its allowed value limit at 767 btu/hr/ft2. Figure 3-11, Receptor Point Summary
15.
This completes our initial design. Save the case.
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Simple Flare Stack Design
3.1.4 Print Results 16.
Select the Print button in the Case Navigator tool bar. The Report Preview view shown below opens. Note that this will open in a new window, independent of the main Flaresim view.
Figure 3-12, Report Preview
17.
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Select the report elements you wish to see printed. To see what the report will look like with the current set of elements you will need to click the Refresh button to update it.
Getting Started
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In order to allow us to compare these results with future results you will need to ensure that the Stack Configuration, Tip Results - General and Flame Shape elements and the Receptor Point results are included. Once you have set your preferred report options you can click the Save Options button to save your report options to a configuration file. Your chosen options will also be saved with the case. 18.
When you are happy with the options you have chosen click the Print button to send the report to your default printer. The standard Printer Dialog view shown below will appear to allow the printer and other options to be selected.
Figure 3-13, Printer Dialog
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Sonic Tip Design
3.2 Sonic Tip Design 3.2.1 Objective and Data The design that we produced in Example 1 meets our design radiation limits but requires a long 247ft stack. Since we are designing a flare stack for an offshore platform we wish to minimise the length and hence the weight of the flare stack as much as possible. Therefore we will attempt to reduce the required flare stack length by redesigning the system using a sonic flare tip. The fluid data, environmental data and radiation limits are the same as for Example 1.
3.2.2 Open Starting File 1.
If you are continuing from Example 1 you should save your case before continuing using the button from the tool bar at the top of the Case Navigator. Skip to step 3.
2.
Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples folder created by your Flaresim installation. This will usually be in the Softbits\Flaresim 3.0 folder in your configured “Documents” folder. Select the file “Example 1 Result.fsw” and click the Open button.
3.2.3 Create Sonic Tip 3.
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Create a new tip by selecting the Tip branch in the Case Navigator view and then clicking the Add button or by selecting the Add - Tip drop down menu option.
Getting Started
4.
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On the Details tab of the Tip view that opens enter the following data: Name = “Sonic Tip” Tip Type = Sonic Number of Burners = 1 Seal Type = None Fraction Heat Radiated Method = High Efficiency
5.
On the Noise Input tab of the Tip view enter the following data: Combustion Noise Method = Standard Reference.
6.
Move to the Location & Dimensions tab and enter the following data: On Stack = Stack_1 Length = 3.0ft Angle to Horizontal = 90 Angle to North = 0 Exit Diameter = 18in Riser Diameter = 18in Contraction Coefficient = 1.0 (default) Exit Loss Coefficient = 1.0 (default) Roughness = 9.843e-4in (default) Calc Burner Opening = Selected
7.
Click on the Fluids tab and enter the following: Fluid Name = Fluid 1 Fluid Mass Flow = 100,000lb/hr
8.
At this point the Status Text at the bottom of the Tip view should indicate that the tip data is complete. Close the view.
9.
In the Case Navigator, select the branch labelled Tip 1 and then click the Ignore button. The icon beside the label should turn to a icon to confirm that the tip will not be included in the calculations.
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Sonic Tip Design
3.2.4 Run & Review Calculations 10.
We are now ready to run the calculations. Click the large button at the top of the Case Navigator. Once Flaresim has finished calculating, check the Errors/ Warnings/Info log panel to confirm that the expected calculations for the two Receptor Points have been completed. Note that if earlier messages in the log panel are causing confusion, you can click the right mouse button over the log panel to access a pop-up menu which provides a Clear option to remove the current log messages.
11.
We are now ready to review the results. Open the Stack view for the Main Stack. The new length calculated for the stack is 68ft.
12.
Open the Receptor Summary view. As shown below, this indicates that the Stack Base receptor point is now the controlling limit since the thermal radiation at this point is calculated as 1500 btu/hr/ft2. The radiation at the Helideck receptor point is 543 btu/hr/ft2.
Figure 3-14, Sonic Tip, Receptor Summary
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Getting Started
13.
Save the new design to a new case name.
14.
Generate a report for this new case using the Print tool bar button.
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3.2.5 Compare Results Our new design with the sonic flare tip is clearly better since it leads to a much shorter stack that will save a great amount of weight and hence cost over our initial design using the pipe flare tip. It is worth doing a detailed comparison to understand the difference between the designs. 15.
Reopen the original case “Example 1 - Results.fsw” and click the Print tool bar button. Since reports are generated in separate windows then you will now have two report windows that you can compare side by side. Note that both cases are open simultaneously in Flaresim and you can switch between them using the Windows menu option. Alternatively you can use your Internet browser to view the saved report files “Example 1 - Result.html” in the “Samples\Example 1 - Result” sub-folder and “Example 2 Result.html” in the “Samples\Example 2 - Result” subfolder. (usually in [Documents]\Softbits\Flaresim 3.0).
16.
Find the Tip Data - Results section in the reports. The fraction of heat radiated value for the Pipe flare design is 0.35 while that for the Sonic design is 0.1. The fraction of heat radiated by a flare is a critical parameter in the design. Pipe flares exhibit relatively poor mixing of air with the flared fluid and as a result the flame contains many partially combusted luminescent carbon particles that give it an orange colour and a relatively high fraction of heat radiated. Sonic flare tips are designed to maximise the mixing of air and the flared fluid and so burn with a clearer flame with lower heat radiation.
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Sonic Tip Design
By selecting the appropriate F Factor method to calculate the fraction of heat radiated in both our designs we have allowed the program to calculate an appropriate value for the different tips. However since this is such an important factor in the design, the heat radiation factor to be used should be confirmed with your flare system vendor prior to the final design. Should you wish to use a heat radiation factor supplied by a vendor you should set the method to User Specified and enter the value. 17.
Still in the Tip Data - Results section of the reports find the flame length. For the Pipe flare design this is 173 ft. while for the Sonic flare design the flame length is 88ft. Note that the flame length calculated by the API method is the same in both cases. Sonic flare tips by their design and by their greater gas exit velocities lead to a flame shape that is shorter and stiffer compared to that of a pipe flare. As a result the flame is less affected by wind and stays closer to the tip and thus further from the platform. This can be seen most clearly by comparing the 3D plot of the Flame Shape in the reports. Finally in the Tip Results section of the reports find the tip back pressure i.e. tip inlet pressure. For the Pipe flare this is 14.7 psi while for the Sonic flare it is 26.0 psi. The fact that the sonic tip is operating at choked conditions means that the pressure drop over this type of tip is much higher than for the pipe tip. Thus a sonic tip can only be used if the resulting back pressure on the flare system is not so high as to prevent safe relief of the gas.
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Getting Started
3-23
3.3 Two Tip Design Comparison of our two designs using the pipe tip and the sonic tip shows that the sonic tip is much the better since it produces a shorter, stiffer and above all a flame with a lower F Factor than the pipe flare. This means that the flare stack can be much shorter while still meeting radiation limits. Given the advantages of the sonic tip it might appear that we should always specify this type of tip. However we have also seen that the sonic flare tip results in higher back pressures on the flare system. In many cases this additional back pressure will be too high to allow safe relief from all the possible relief sources in the process. Therefore it is common to see designs with both high and low pressure flare systems relieving through different tips.
3.3.1 Objective and Data The relieving sources in our process have been reviewed to check that the new back pressure resulting from the sonic tip is acceptable. The review has shown that 10,000 lb/h of the material being flared cannot be relieved safely at the new higher back pressure. As a result we have decided to split our design so this 10,000 lb/h is relieved through a low pressure flare system leading to a pipe tip with the remaining material flowing through a high pressure flare system to a sonic tip.
3.3.2 Open Starting File 1.
If you are continuing from Example 2 you should save your case before continuing using the Save tool bar button the Case Navigator. Skip to step 3.
2.
in
Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples sub-folder of your Flaresim installation (usually [My Documents]\Softbits\Flaresim 3.0) and click the Open button. 3-23
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Two Tip Design
3.3.3 Update Tip Data 3.
In the Case Navigator view double-click the Sonic Tip branch to open the view for this Tip. On the Fluids tab change the flow rate to 90,000 lb/h. Close the view.
4.
Open the view for the Tip 1 by double-clicking this in the Case Navigator view or by selecting it and then clicking the View button. Rename the tip to “Pipe Tip”. On the Fluids tab change the flow rate to 10,000 lb/h. Then clear the tick from the Ignore check box to activate this tip again. Close the view.
3.3.4 Run & Review Calculations 5.
We are now ready to run the calculations. Click the large button at the top of the Case Navigator. Check the Errors/Warnings/Info log panel to confirm that the expected calculations for the two Receptor Points have been completed.
6.
We are now ready to review the results. Open the Stack view for the Main Stack. The new length calculated for the stack is 96ft.
Figure 3-15, Stack View
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Getting Started
7.
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Open the Receptor Summary view. This indicates that the Main Stack receptor point is still the controlling limit since the thermal radiation at this point is still calculated as 1500 btu/hr/ft2.
3.3.5 Update Pipe Tip In reducing the flow through the Pipe tip we have changed its performance. 8.
Open the Tip view for the Pipe tip. You will see on the Details tab that the fraction of heat radiated from this tip has been calculated as 0.38 whereas before it was 0.35. The reason for this is the greatly reduced velocity, 0.02 mach, through the tip which reduces the tips efficiency. For efficient operation the velocity should be 0.2 mach or higher.
9.
On the Location & Dimensions tab, click the Size Me button. Set the Mach number to 0.3 and set “Use Nominal Diam” to “No” and the tip size will be calculated as 4.6 in. Set “Use Nominal Diam” back to “Yes” and an nominal diameter of 5 inch will be selected. If you wish to check the actual Mach Number at the selected tip size, use the Nominal Diameter drop down list and reselect 5 inch to update the calculated Mach Number which will be 0.25 Mach. This is acceptable so click the Ok button. The tip size and riser diameter will automatically be updated to the new selected diameter.
10.
Now recalculate the case. The new exit velocity is 0.25 mach and the fraction of heat radiated is now 0.34. The improvement in efficiency of this flare reduces the calculated size of the stack to 90ft.
11.
Our two tip design is complete so save the case.
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Working With Isopleths
3.4 Working With Isopleths To see details of the thermal radiation around the flare Flaresim provides the Receptor Grid objects that will calculate the radiation for a grid of points that can be used to generate isopleth charts showing lines of constant thermal radiation. Similar isopleth charts can be displayed for noise and surface temperature results. Our model already has one receptor grid called Grid 1. This was automatically generated for us by the Setup Wizard. It shows a plan view around our flare stack at the grade elevation i.e. 0ft. Since the Helideck is the main area of interest we will update this grid to the correct elevation.
3.4.1 Open Starting File 1.
If you are continuing from Example 3 you should save your case before continuing using the Navigator tool bar. Skip to step 3.
icon from the Case
2.
Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples folder in your Flaresim installation ([Documents]\Softbits\Flaresim 3.0), select the file “Example 3 - Result.fsw” and click the Open button.
3.
Since the Helideck is one of the main areas of interest, we will update the receptor grid to plot the radiation at this level. Open the Grid 1 object by double clicking on it in the Case Navigator. Once open, change the name to “Helideck Plan” and change the elevation offset to 30ft. Also update the number of points for each axis to 41. Note that the number of points in the grid is not critical - a higher number will generate smoother, more accurate isopleths at a cost of increased calculation time.
4.
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In the Case Navigator view select the Receptor Grid branch and click the Add button (alternatively select the Add -
Getting Started
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Receptor Grid drop down menu option) to create and open the view for a new Receptor Grid object. 5.
Enter the following data to create a grid for the vertical cross-section through the axis of the flare. Name = Helideck Elevation, Orientation = Elevation-Northing, Easting = 0ft, Elevation Min = -100ft, Elevation Max = 300ft, Elevation Points = 41, Northing Min = -500ft, Northing Max = 300ft, Northing Points = 41. The receptor point properties are left at the default values.
6.
Re-run the case. When the run is complete you will be able to inspect the isopleth plot by opening the grid view, clicking on the Radiation tab and then selecting Plot as the Display option. Similar plots for noise and surface temperatures can be found on the Noise and Temperature tabs.
7.
You can customise the isopleth lines displayed on the plot by clicking the Customise button to open a plot properties view as shown below. Select the Contour Details tab and select the check boxes to show only the isopleth values for 600, 1500, 3000, 5000 and 10000 btu/hr/ft2 as shown in Figure 3-16 below. Note the colours of each isopleth can be customised by clicking on the line colour panel and selecting the colour from the pop-up colour picker dialog. When your updates are complete you can click the button at the bottom of the Customise window to copy your changes to other isopleths of the same type.
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Working With Isopleths
Figure 3-16, Isopleth Customisation
8.
Isopleth plots will be included automatically as part of Flaresim standard reports. A plot may also be exported as a standalone graphics file clicking the Export button on an isopleth result tab when the display option is set to Plot. This displays a standard file save dialog which allows the type of graph to be exported to be selected from the Save as type drop down. Allowed types are JPG, BMP and PNG bitmap formats or WMF and EMF vector formats. Note vector format files are more suitable for re-scaling and inclusion in reports. If the Export button is clicked while the isopleth results are displayed as a Table the save dialog will provide options to save the results table to a text file (of comma separated values) or to an Excel spreadsheet file.
9.
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A graphical report that displays an isopleth plot together with a summary of the model data can be generated from the Graphical Report tab on the Receptor Grid view. Simply select the type of plot to be produced, the layout file and click the View Graphic Report button. A sample of the output produced is shown below. Note this is a modal
Getting Started
3-29
window that must be closed before you can use other parts of Flaresim. Figure 3-17, Graphic Report View
10.
Graphic reports can be printed or exported as graphics files using the Print Graphic Reports tool bar button . For example to export a graphic report of the radiation isopleth for the Helideck Plan view, select the Helideck Plan in the list of available receptors grids, select the check box for the radiation plot and JPEG Bitmap as the file type as shown below. Then click the Save Graphic Reports button. A browser window will open to allow the output folder to be specified. The graphic reports will then be automatically created and saved and the Log area of the Flaresim screen 3-29
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Working With Isopleths
will list the output location of the saved files. Note the layout file used will be that specified on the Graphic Report tab for each receptor grid. Figure 3-18, Output Graphic Report
3.4.2 Adding a Flaresim Overlay Flaresim allows drawings to be overlaid on isopleth plots. Drawings can either be imported or generated using the internal overlay editor. In this example we will create a simple plan view within Flaresim.
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11.
In the Case Navigator, select the Overlay branch and click the Add button. A new overlay object called Overlay 1 will be created and displayed. Change the name to “Helideck Plan”.
12.
In the “Update Details From Grid” section of the Details tab, select the “Helideck Plan” grid and click Update. The Overlay dimensions are updated with those from the Helideck Plan Grid.
Getting Started
13.
Select the Editor tab and click the zoom in
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and zoom
out buttons and/or resize the view until you can see the full drawing. Check the Show Stacks check box to display the location of the stack in the drawing to act as a guideline. Not this will not form part of the drawing. 14.
Now click the Add Rectangle button and draw a rectangle to represent the platform outline from the top left corner at -200,0 to the bottom right corner 50,-200. This is done by moving to the first point using the displayed X,Y coordinates at the left of the view as a guide, clicking and holding the left mouse button then dragging to the second point.
15.
Add a second rectangle to represent the helideck from the points -50,-100 to 30, -180.
16.
Click the ellipse button and draw a circle within the helideck rectangle by moving to the point -50, -100, clicking and holding the left mouse button and dragging to the point 30, -180.
17.
Click the text button and then click the drawing in the middle of the helideck circle. A vertical flashing bar will appear to indicate the text insertion point. Type the letter H and then hit the enter key to complete the text entry. If the text is too small, click the select button and then select the text you have just entered. A set of selection points will appear around it to indicate that it has been selected. Now click the properties drop down menu and select the Text Font option to open a standard font dialog to allow the text size and style to be defined. A size of around 24 pt is probably suitable.
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Working With Isopleths
If required the selected text can also be moved by clicking and dragging with it the left mouse button - the yellow dot will indicate the point to click for dragging the text. The overlay picture is now complete and should look something like the view below. Figure 3-19, Completed Overlay
18.
Next open the “Helideck Plan” Receptor Grid and go to the Plot Overlay tab. Select the Use Flaresim Overlay radio button and then in the drop down menu that appears select the overlay we have just created, “Helideck Plan”. Finally tick the Show Overlay check box. Now go to the radiation tab. The overlay is now displayed as the background picture to the isopleth as shown below.
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Getting Started
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Figure 3-20, Isopleth with Overlay
19.
Save the case. The overlay file we have created will be automatically saved in the Flaresim case folder (i.e. the sub folder created with the same name as the Flaresim case which contains the report data) with the file extension “.fso”.
3.4.3 External Overlay File The other method of displaying an overlay with your isopleth plots is to link to an external graphics file. The best type of background drawing to import is a scaled vector drawing i.e. a Windows metafile (.wmf) or enhanced metafile (.emf) but bitmap files (.bmp, .png and .jpg files) can also be used. Given that the locations of the stacks etc. in your Flaresim model are matched to the drawing on import the
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Working With Isopleths
isopleths will be correctly positioned in relation to the drawing. The following example shows how this is done. 20.
Open the Plot Overlay tab in the Helideck Elevation Receptor Grid. We know that the drawing we are going to import represents dimensions of 1050 ft wide by 750 ft high. The point corresponding to the base of the main stack (0,0) in the model is located at the point 500, 350 in the drawing.
21.
Ensure the Details radio button is selected in the External File Details section and enter the following values:Elevation - Min = 0ft, Elevation - Max = 750ft Northing - Min = 0ft Northing - Max = 1050ft. Location of Flaresim Origin - Elevation = 350ft Location of Flaresim Origin - Northing = 500ft
22.
Click the Browse button to import the background graphics file. The file to import is called elevation.wmf and is located in the Samples\example 4 - result folder. You will need to select “Windows Metafiles (.wmf)” in the “Files of Type” drop down in the File Open view to select this. Click Ok. You can now click the Preview radio button to see the imported graphic file together with a blue outline rectangle which shows the extents of the current receptor grid on the drawing.
23.
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Reselect the Details radio button and set the Show Overlay check box. Move to the Radiation tab and you should see your overlay displayed on the isopleth as shown below.
Getting Started
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Figure 3-21, External Overlay File
24.
Our work enhancing the isopleth plots is now complete. Save the case.
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Welltest Burner Design
3.5 Welltest Burner Design Offshore platforms often include a facility for burning off liquids produced during well tests. Flaresim is capable of modelling this type of burner in addition to the conventional safety release flares.
3.5.1 Objective and Data A welltest burner capable of burning 30,000 lb/hr of liquid is to be added to our design. The properties of the liquid to be burned are as follows: Fluid Material Hydrocarbon Liquid Flow 30,000 lb/hr Mol Wt. 52.9 Vapour Temp. 100 F Heat of combustion 19,550 btu/lb Tip Diameter
12 in
3.5.2 Open Starting File 1.
If you are continuing from Example 4 you should save your case before continuing using the Navigator tool bar. Skip to step 3.
2.
icon from the Case
Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples sub-folder in the Flaresim installation folder (usually [My Documents]\Softbits\Flaresim 3.0) select the file “Example 4 - Result.fsw” and click the Open button.
3.5.3 Add New Fluid Data 3.
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In the Case Navigator view select the Fluids branch and then click the Add button to create a new Fluid and open its view.
Getting Started
4.
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Complete the view with the following entries; Name = Welltest Liquid, Temperature = 100F, Ref Pressure = 14.7psi Mole Weight = 52.9, LHV = 19,550 btu/lb, Cp/Cv = 1.2, LEL = 1.7%, Saturation = 100%. The Critical Temperature and Critical Pressure fields can be left blank. The completed view is shown below. Close the view when the data has been entered.
Figure 3-22, Welltest Fluid View
3.5.4 Add New Stack 5.
In the Case Navigator view select the Stacks branch and then click the Add button to create a new Stack and open its view.
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Welltest Burner Design
6.
Enter data for the new stack as follows, leaving other entries at their default values; Name - Welltest Boom, Location Northing = -200ft, Easting = 0ft, Elevation = 0ft, Dimensions section Length = 55ft, Angle to Horizontal = 0 deg, Angle to North = 180 deg. These entries define our new stack as a horizontal boom on the opposite side of the platform to our main flare stack. The completed view is shown as Figure 3-23. Close the view when complete.
Figure 3-23, Welltest Boom View
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Getting Started
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3.5.5 Add Welltest Burner Tip 7.
In the Case Navigator, select the Tips branch and click the Add button to create and view a new Tip object.
8.
On the Details tab of the Tip view enter the following data; Name = Welltest Burner, Tip Type = Welltest, Number of Burners = 3, Fraction Heat Radiated Method = User Specified Specified Fraction Heat Radiated = 0.3 All other values should be left at their defaults.
9.
On the Location & Dimensions tab enter the following, leaving other values at their defaults; On Stack = Welltest Boom, Length = 0ft, Angle to Horizontal = 0 deg, Angle from North = 180 deg. Exit Diameter = 12 in (Default) Note the burner length and orientation fields serve to locate the precise location of the flame and the initial flame direction. Even when the burner length is 0ft as here, the orientation fields must still be entered.
10.
On the Fluids tab select the Fluid as Welltest Liquid and enter the flow rate as 30,000 lb/hr. Close the view.
3.5.6 Add New Receptor Point 11.
Add a new Receptor Point in the usual way. Define the following data to locate the receptor point at the base of the welltest burner boom;
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Welltest Burner Design
Name - Base Welltest Boom, Northing = -200ft, Easting = 0ft, Elevation = 0ft. All other fields may be left at their default values. Close the view.
3.5.7 Run & Review Calculations
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12.
In the Case Navigator view, select the Stack 1 object. Clear the Size This Stack check box. Now click the Ignore button. This will exclude the two tips on the main flare stack from the calculations.
13.
Run the calculations by clicking the large button labelled “Click to Calculate”. Check in the Errors/Warnings/Info log panel that the case has run and calculated correctly.
14.
Open the Receptor Summary view. The results, see Figure 3-24, show that the radiation limits for our original two critical locations that we have defined are met. The radiation at the base of the well test burner stack is 1406 btu/hr/ft2.
Getting Started
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Figure 3-24, Receptor Summary
15.
Save the case.
3.5.8 Add Water Screen The radiation calculated at the base of the welltest burner stack is acceptable for brief exposure only. Since more extended exposure might be required it is necessary to reduce the radiation. While this could be achieved by extending the length of the stack this would be an expensive option due to the added weight. It is normal to reduce radiation from welltest burners using water screens. The effect of these can be modelled in Flaresim through the installation of shield objects 16.
Add a Shield object either by clicking the Shield branch in the Case Navigator view and then the Add button or by using the Add - Shield menu option according to your preference. 3-41
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Welltest Burner Design
17.
Enter data in the Details tab of the new Shield view as follows; Name = Water Curtain, Radiation - Type = Water Screen Radiation - Layer Thickness Calculation = User Radiation - Layer Thickness = 0.5 in Noise - Transmissivity = 1.0 [default]
18.
Select the Sections tab. The first section is already created for you. In the lower half of this view click the Add Vertex button 4 times to create a rectangular shield section with 4 corners or vertices.
19.
Enter the following data; Name - Water Curtain Vertex 1 = Northing -205 ft, Easting, 50 ft, Elevation 40 ft Vertex 2 = Northing -205 ft, Easting, 50 ft, Elevation -10 ft Vertex 3 = Northing -205 ft, Easting, -50 ft, Elevation -10 ft Vertex 4 = Northing -205 ft, Easting, -50 ft, Elevation 40 ft Note it is a requirement when entering the locations of the vertices that each point is directly connected to the next point in the list as shown below. Flaresim will attempt to sort the points to meet this criteria if necessary.
Figure 3-25, Shield Section Input
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Getting Started
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The completed form is shown below. Figure 3-26, Complete Shield Section Editor
20.
The Shield view should now show that the shield data setup is complete. Run the updated case and inspect the results. The radiation value at the base of the welltest burner stack has been reduced to an acceptable value of 264 btu/hr/ft2. The radiation isopleth for the plan view clearly shows the effect of the shield, see Figure 3-27. Save the case..
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Welltest Burner Design
Figure 3-27, Isopleth plot for Helideck Plan View
3.5.9 Evaluate Rate of Temperature Rise Since we are relying on the water screen to reduce thermal radiation in normal use, we should check the situation when the water screen fails. Given data on the receiving surface, Flaresim is able to calculate the rate of temperature rise. 21.
Open the view for the Base Welltest Stack receptor point and select the Properties tab. Update the data as follows; Emissivity = 0.7, Absorbtivity = 0.7, Area Ratio = 2.0, Mass = 10.4 lb/ft2, Mass Cp = 0.1075 btu/lb/ft, Initial Temperature = 60F.
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Getting Started
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This data represents a steel plate, 0.25in thick. The Area Ratio of 2.0 indicates that one side of the plate is exposed to the flare radiation. The On Plane value at its default value of None is a conservative assumption that means that no credit will be taken for radiation striking the plate at an angle. Enabling this option to select the angle of the plate requires selection of the Export Mode option in the Calculation Options view. 22.
Select the Water Curtain shield object in the Case Navigator and click the Ignore button. Then run the calculations.
23.
In the Thermal Results tab of the Base Welltest Stack receptor point you can inspect the rate of temperature rise results in tabular or graphical form. The results show that the temperature will rise to 83F after 2 mins on its way to a final temperature of 122F. Save the case.
3.5.10 Check Safety Case The results with only the welltest burner in use show that the original design radiation limit for the helideck is met. However we still have to consider the situation when a safety release occurs while the welltest burner is in use. 24.
Select the Main Stack, Stack 1 in the Case Navigator view and click the Activate button to restore it to the calculations. You will probably find that the stack is not ready to run since its length was originally being calculated we have been running the case with the stack set to ignored. Set the stack length to 90ft, the value calculated in Example 3.
25.
Click the Calculate button to run the model.
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Welltest Burner Design
Open the Receptor Point summary. The results show that the thermal radiation at the Helideck receptor is 1145 btu/hr/ ft2, significantly exceeding our limit of 600 btu/hr/ft2. At this point we might consider increasing the length of either the Main Stack or the Welltest Stack in order to ensure that the radiation limits are met again. However it may also be possible to consider the circumstances under which the welltest burners would be used at the same time as the main flare. Perhaps procedures could be established to prevent helicopter operations while the welltest burner was in use meaning that this higher radiation value is acceptable. It is appropriate to emphasise at this point that Flaresim is a tool for analysing the performance of flare systems. It cannot replace the engineers judgement in selecting the appropriate conditions to model or determining whether a particular set of results represent an acceptable or a dangerous situation.
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Getting Started
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3.6 Gas Dispersion Flaresim includes two types of gas dispersion model intended for two different types of analysis A jet dispersion calculation models dispersion of flared fluid close to the tip to identify the potential for dangerous gas concentrations in flame out conditions. A Gaussian dispersion calculation models dispersion of flared fluid or combustion products over longer distances. The aim of this section is to illustrate how to use each of these models.
3.6.1 Objective and Data A new case with the following data will be used. Flared Fluid Methane Ethane H2S Temperature Ref Pressure Flow
0.9 mole frac 0.08 mole frac 0.02 mole frac 75 C 1.013 bar a 50000 kg/hr
Mechanical Data Tip diameter Tip length Stack location Stack length Stack orientation
387.4mm (16in) 1m At origin, 0, 0, 0 20m Vertical
Environment Data Temperature Wind
15 C 10 m/s from North
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Our objective will be to analyse the gas dispersion around the flare in normal operation and flame out conditions.
3.6.2 Load or Create Base Case 1.
If you wish to build the case from scratch then either select the File - New menu option or click the icon in the tool bar. The Setup Wizard will appear. Select the European units set on the opening page for easy of entering the remaining data. Work through the Fluid, Tip, Environment and Stack tabs entering the data defined above. Once you have entered the Stack data you can click the Finish button to accept the default data for Receptors and Calculation options. Skip to step 3.
2.
Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples sub-folder in the Flaresim installation folder (usually [My Documents]\Softbits\Flaresim 3.0) select the file “Example 6 - Starter.fsw” and click the Open button.
3.6.3 Jet Dispersion Calculation In this exercise we run a jet dispersion study to study the flammable gas concentrations around the flare in the event of a flame out. 3.
Before enabling the jet dispersion calculations we will create a new Receptor Grid to see the results more clearly. Select the Receptor Grid branch in the Case Navigator and click the Add button. In the new view enter the following data. Name = Elevation Grid Plane = Elevation-Northing Grid Offset = 0m Elevation Minimum = -100m Elevation Maximum = 300m
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Northing Minimum = -300m Northing Maximum = 100m Leave remaining values at defaults. 4.
Open the Calculation Options view by selecting it in the Case Navigator and clicking the view button. Select the check box labelled Jet Dispersion in the Include Options section of the General Tab. Click the Calculate button
5.
Return to the view for your Elevation receptor grid and select the Concentrations tab. You should see a result that looks something like that shown below.
Figure 3-28, Jet Dispersion Initial Result
The jet dispersion calculation shows the concentrations of the flare fluid in the event of a flame out and is useful for 3-49
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establishing the regions in which a flammable gas concentration may be obtained. At first sight the result above looks unrealistic since the concentration isopleths do not appear connected to the flare tip. This is a function of the limited number of points calculated in the default grid. 6.
In your Elevation grid view, go back to the Extent tab and increase the number of calculated points for both Elevation and Northing dimensions to 51. Click the Calculate button again. Return to the Concentrations tab and you should see the following, more accurate result.
Figure 3-29, Final Jet Dispersion Result
Save the case. 3-50
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3.6.4 Gaussian Dispersion, Contour Plot In this exercise we will study the dispersion of H2S from the flare tip in the event of a flame out. 7.
Create a Dispersion Object by selecting the Dispersion branch in the Case Navigator and clicking the Add button. In the Dispersion view enter the following data on the Input Data tab as shown below. Name = H2S Contour Pollutant Source = Flared Fluid Calculation Type = Contour Plot Contours Height = 0m Northing Minimum = -1000m Northing Maximum = 0m Easting Minimum = -500m Easting Maximum = 500m Number of points, Northing and Easting = 41
Figure 3-30, Gaussian Dispersion Input Tab
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8.
On the Pollutant Data tab select the H2S component only. For a contour plot, only one component can be selected.
9.
Open the Calculation Options view and select the Gaussian Dispersion checkbox to enable these calculations. Click the Calculate button
10.
Select the Results tab and then the Plot option for the display. The plot shows the ground level concentration contours for H2S downwind of the stack as shown below
Figure 3-31, H2S Contour Plot
11.
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The results shown have been calculated at the default environmental conditions with atmospheric stability characterised as Class D with dispersion coefficients applicable to Rural terrain around the flare. Open the Environment view at the Dispersion Data tab and test the effect on the dispersion results as you change the Atm.
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Stability class from A (most turbulent) to F (most stable) and the effect of changing the terrain from Rural to Urban. You will see that the H2S concentrations are higher closer to the flare when atmosphere is more turbulent and when urban terrain classification is used. The sensitivity of the results to these parameters shows the necessity of selecting the appropriate environment settings for your particular flare location.
3.6.5 Gaussian Dispersion, Downwind Plot In this exercise we will consider the downwind concentrations of pollutants in the combustion gases of the flare when it is operating. 12.
In the Case Navigator select the Dispersion branch and click Add to create a new dispersion object. In the Input Data tab of its view enter the following data. Name = Combustion Emissions Pollutant Source = Combustion Gas Calculation Type = Downwind Line Plot Line through Point = Origin Height for Calculation = 0m Downwind Distance Minimum = 0m Downwind Distance Maximum = 10000m Number of points = 41
13.
Select the Pollutant tab. Select the SO2, NO, CO and Methane pollutants for calculation by checking the box alongside these components. Some of the components in this list, the CO2, H2O, SO2 are calculated directly from combustion of the components in the flared gas. The Fluid view, Combustion Results tab shows the stoichiometric fraction of each of these components generated by combustion of the flared gas. The remaining components, NOx (assumed as NO), CO and unburnt hydrocarbon (assumed as CH4) are calculated as 3-53
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typical emissions resulting from hydrocarbon combustion. The quantities of each component generated is calculated by default using the global basis defined on the Calculation Option view Emissions tab. Alternatively in Expert Mode the emissions basis for each Tip can be specified on the Emissions tab of the Tip view. The quantities of each component in the combustion gases for each Tip are displayed on the Combustion Results tab of the Tip view. 14.
Since the dispersion of the combustion gases will be dependent on the flame temperature we will now set this. Open the Tip View and select the Fluids tab. At the bottom of this view you may input a value for the flame temperature or clear the specified value to allow it to be calculated from the specified combustion air ratio. Set the Combustion Air ratio to 3.0 and clear the specified flame temperature.
15.
Open the Environment view and set the Atm. Stability Class to PasquillB. Click the Calculate button.
16.
Return to the Combustion Gas Results tab of the Tip view to see the calculated flame temperature of 721 C and the combustion gas compositions. In the Combustion Gas dispersion view go to the results page and select the plot result to view the results as shown below. The peak concentration of SO2 is calculated at 68 µg/m3 at a distance of approximately 1500m downwind of the flare tip.
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Figure 3-32, Combustion Gas Dispersion Downwind Plot Results
17.
As in the previous example, open the Environment view to the Dispersion Data tab and test the effect of changing the Atm. Stability Class and Terrain class settings. You will find that for stable atmospheric conditions, stability classes E, F that the emission concentrations are still rising at the maximum downwind distance we have defined (10,000m). If you wish you can increase the maximum downwind distance on the Input Data tab to calculate the results further downwind.
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3.6.6 Dispersion Analysis Comments It is worth making the following general comments on the dispersion analysis capabilities of Flaresim. The jet dispersion analysis for flammable gas concentrations is based on the Cleaver & Edwards jet dispersion model which is regarded as a reasonable model for concentrations close to the source. However it does assume dispersion in “free air” and does not consider the effect of structures which might modify dispersion patterns and lead to higher concentrations of flammable gas than predicted by Flaresim. A more detailed analysis with specialised software would be required in these situations. The Gaussian dispersion calculations for combustion gases and flared fluid over longer distances is a simpler theoretical model that does not include detailed terrain effects. As such it should be considered as suitable for screening calculations to indicate a possible need for more detailed analysis. Chapter 12 has additional comments on the implementation of the Gaussian dispersion model in Flaresim.
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