Note: This is a work in progress.
The goal of this project is to work towards creating a user interface in ArcView through which the FORTRAN model naUTilus will be run. The results of the model will also be displayed.
To accomplish this, the programming language Avenue will be used. As an additional objective, I hope to gain some level of proficiency in using Avenue.
While making a complete interface between ArcView and naUTilus for the purpose of this term project may not be an achievable goal, the desired goal is to enable data output from the naUTilus model to be visually displayed in ArcView.
Work done towards creating an input interface will also be described.
With the passing of the Clean Air Amendments of 1990, industrial sewers have received more focus as a source of Hazardous Air Pollutants (HAPs). Of particular interest are emissions of volatile organic compouds (VOCs) in petroleum refining and organic chemical manufacturing. VOC emissions occur at drains or manhole covers within specific process units (referred to as ISBL or inside the battery limit) or from manhole covers or elevated vents in sewers which collect ISBL discharges (referred to as OSBL or outside the battery limit). In large and mid-sized refineries or chemical manufacturing facilities, emissions may be distributed over thousands of openings, making monitoring programs unfeasible. In the absence of monitoring, VOC emissions are predicted using emission factors or mathematical models. naUTilus was developed to address this issue, as an improved method over highly conservative models which tend to overestimate emissions.
However, present use of naUTilus requires familiarity the numbering scheme of network components and branch connectivity in order to create a lengthy input file. By creating a user interface in ArcView, this project makes naUTilus easier to use, increases the power of the model by facilitating it's application to larger facilities, and spatially represents the input and output.
Industrial sewer networks can be classified into two sections. The several drains and pipes which are involved in a specific process unit is designated as "inside the battery limit" (ISBL). Several ISBL units will drain into a larger set of main lines categorized as "outside the battery limit" (OSBL).
Several features comprise a sewer network: reaches, nodes, drops, manholes, and drains. Liquid-to-air mass transfer occurs in the reaches (also referred to as branches) and at drop structures. Emissions occur at manholes, drains, and elevated vents by air exchange.
naUTilus is a computer model written in FORTRAN which analyses the data from an industrial sewer network and predicts the emissions of volatile organic compounds (VOCs) from the network. It is the product of a great deal of research done by several individuals under the supervision of Dr. Richard Corsi at the University of Texas at Austin.
naUTilus applies mass transfer principles to estimate liquid/gas mass transfer in reaches and fluid mechanic and heat transfer principles to calculate air exchange rates between the sewer network and the ambient atmosphere. Several relationships used in naUTilus were experimentally derived. The inputs to naUTilus are the specifications of an industrial sewer network: flow rates, concentrations, temperatures, and sewer characteristics. naUTilus outputs the emissions and flow rates in that sewer network. The two sections of a sewer network (OSBL and ISBL) are handled by different sets of code in the naUTilus model
At present, a great deal of knowledge of the model is needed to successfully run the naUTilus program. The input consists of a text file; it is essentially a string of numbers representing the system it is to model in a very specific format. To see an example input file, click here. Similarly, the output is a text file listing the output. To see an example output file, click here. The example files were for a sewer network consisting of 110 branches and 83 nodes.
The input file describes flow and concentration inputs to the sewer network as well as the connectivity of the branches and nodes. Information on the chemical of interest, pipe diameters and slopes, drop heights and locations, opening size, temperature, and wind speed are also a part of the input file.
To facilitate the use of naUTilus, a graphic user interface (GUI) is desired. Input and output could then be directly associated with a visual (schematic) of the sewer network . The user will be prompted for input and sewer characteristics will be more easily modified. Results would also be output in a visual, easy to interpret display.
The naUTilus/ArcView interface is created using a series of Avenue scripts. Avenue is an object oriented programming language specific to ArcView. Through Avenue, the digitized map entered to ArcView will be able manipulated to create the input file needed by naUTilus. The model will also be executed from within ArcView. In turn, ArcView will read the model output and, through Avenue scripts, display the data in the desired visual format.
To define a term project of reasonable scope, the selected goal was to enable ArcView to read and display naUTilus output for an OSBL system.
The following steps were required to display naUTilus data
For help in digitzing, see Exercise on Digitizing Coverages in AutoCAD and Arc/Info.
The above example shows DXFARC used on a file called "dposbl.dxf" to create a coverage called "branch". It uses the AutoCad layer "branches". This command was repeated for the layer "nodes", creating a coverage called "nodes".
After BUILDING the coverages, they were transformed into shape files and opened as themes in ArcView. The themes are built on for user input and result display.
Note that the coverage "branch" was built in terms of both arcs and nodes. The "node" coverage need only be build for nodes. Each of the two AutoCad layers (nodes and branches) became a shape theme in ArcView. Each feature of the themes was labelled by its unique number. The unique number identifies each branch or node throughout the process of creating an input file, running naUTilus, and displaying the data.
OSBL in ArcView, with branches numbered:
Another problem encountered in creating the digital map of the OSBL network was a discrepancy between naUTilus requirements and the sewer set up. naUTilus assumes flow enters the OSBL system at branches, while the schematic indicated that some inflow occurred at nodes. To solve this problem, a several short branches (1 meter in length) were added at the nodes where this occurred.
In the following graphic (a portion of the OSBL show above), nodes 92,92,94, and 95 are 1 meter branches added to the OSBL.
The comma separated text files consisted of an initial row, holding names used to define the columns of a table, and several rows of numerical data. As an example, see osblnd.txt.
Option one finds the maximum and minimum emissions which occur and divide that range into four equal intervals. This option is considered to display relative emissions ranges. Option two displays emissions between set ranges. The final ranges to be used are yet to be determined and will likely vary by chemical, possibly depending on health effects.
Shown below is an OSBL unit:
These results are shown on an actual industrial sewer network for the chemical Benzene. Hypothetical inputs for flow, temperature, and concentration values were used.
Other works in progress to enhance the naUTilus/ArcView interface include:
Some data has entered into an initial chemical library. The entries for Emm.Lim are fictitious, entered for the purpose of display and experimentation. Values for the other fields are found in literature.
Several steps have yet to be completed for the OSBL portion of the naUTilus code. Work is continuing on all steps.
Work similar to that done for OSBL is being done for ISBL, some
in parallel with steps yet to be completed for OSBL. In particular,
an input interface for both OSBL and ISBL is in the early stages
Some of the work completed for ISBL includes:
Several scripts were written to complete this project and have been mentioned previously in this document. They are not in their final format, as they will likely be modified before the entire research project is complete. However, for the purpose of this term project, they are functional. Each script must be run from the script with the view as the immediately underlying document.
In addition to providing a user friendly interface, the integration of naUTilus and ArcView allows for immediate "hot spot" analysis and the possibility of fenceline risk assessment and municipal sewer applications. "Hot spot" analysis consists of identification of problem areas where emissions may exceed tolerance levels. Fenceline risk assessment would consist of using dispersion models and naUTilus predictions to estimate contaminant levels at the boundaries of a plant. Being able to spatially orient the industrial sewer network would make fenceline risk assessment possible. Applying naUTilus to municipal sewers would further utilize the spatial capabilities of GIS. Emissions could be seen on a wide scale and in relation to other spatial data: streets, streams, land use, and various other data.
Data on some industrial sewer networks is being sought from Shell. This data will include a network schematic, branch lengths, branch diameters, drop structures, flow rates, concentrations, and temperatures.
Presently working on the naUTilus model is David Olson, one of Dr. Corsi's former students who now works for him as a Research Engineer.
On the GIS/ArcView side of this project, I am receiving help from members of Dr. Maidment's research group. Thanks to all who are contributing to this project!
I would also like to thank the Environmental Solutions Program (ESP) for funding this project.
Last edited: 4/23/97