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Site-Wide Modeling for MSS

Site-Wide Modeling for MSS. Robert Opiela, Team Leader Air Dispersion Modeling Team TCEQ, Air Permits Division Austin, Texas October 16, 2007. Introduction. Define concepts Clarify expectations Provide examples. Applicability. MSS related projects Flexible permits

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Site-Wide Modeling for MSS

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  1. Site-Wide Modeling for MSS Robert Opiela, Team Leader Air Dispersion Modeling Team TCEQ, Air Permits Division Austin, Texas October 16, 2007

  2. Introduction • Define concepts • Clarify expectations • Provide examples

  3. Applicability • MSS related projects • Flexible permits • Permits with operational flexibility

  4. New Concepts • Activity • Facility emissions authorized for specific activity • Activity not associated with a facility • Emissions of same pollutant from all activities are evaluated

  5. Not So New Concept (1) • Modeling scenario • Representation of activities from a single source • Examples • Load analyses for EGU • Tank working losses and breathing losses • Short-term analysis separate from annual

  6. Implementation in Modeling • Demonstrating worst-case scenario • Represent all applicable operating scenarios (production and MSS activities) • Key representations included in permit conditions

  7. Not So New Concept (2) • Generic modeling • Model each source/source group at 1 lb/hr • Report results (µg/m3 per lb/hr) for each source/source group • Use ONE model input file, please

  8. Implementation in Modeling • Determining culpable sources • Provides information on source(s) driving worst-case scenario • Allows focus on limited number of sources • Determines site baseline concentrations

  9. Not So New Concept (3) • Emission rate to ESL ratio (E/ESL) • Evaluate site-wide or • Sum source by source for all sources

  10. Implementation in Modeling • Determining limiting pollutant • If this pollutant acceptable, all pollutants acceptable • Determining limiting emission rates • Demonstrates pollutant emission rate by source that would be acceptable

  11. Not So New Concept (4) • Continuous Activity • Theoretically could operate 8760 hours/year but practically could not • Operates from hour-to-hour for many hours/year during any 8760 hours/year • Operates from hour-to-hour for many hours/year on a certain schedule

  12. Not So New Concept (5) • Batch Activities • Activity starts and finishes within a few hours • Significant time between activities • Limited number of activities per year

  13. Expectations • Document all steps in your analysis • Substantiate all claims and representations • Provide technical justifications for all assumptions and selections

  14. Example (1) • Continuous production and one MSS activity • Is MSS activity separate source from all production sources? • In either case, all emissions considered in annual analysis

  15. Example (1) Implementation • Case of MSS simultaneous with production • Model production as one source group • Model MSS activity as one source group • Model using ALL group

  16. Example (1) Implementation • Case of MSS not simultaneous with all production • Model all production activities as one scenario • Model MSS and simultaneous production sources as separate groups in 2nd scenario • Could model MSS and all production together as a short-cut, only if below threshold

  17. Example (1) Implementation • Analyzing exceedances in either case • Consider production and MSS hours of operation separately to adjust number of exceedances • Could consider only production hours of operation as a short-cut

  18. Example (1) Implementation • Annual concentrations • Model production as one source group • Model MSS as one source group at maximum hour emission rate • Add the production concentrations to N/8760 times the sum of the N highest MSS predicted concentrations; N is MSS hours

  19. Example (1) Implementation • Annual concentrations short-cuts • Add N/8760 times MSS GLCmax to production GLCmax, or • Add MSS GLCmax to production GLCmax

  20. Example (2) • Continuous and batch production activities and multiple MSS activities • Much more complicated, but don’t make more complicated than you need to • Recommend you submit a detailed modeling protocol; coordinate with us FIRST before you start modeling

  21. Example (2) Implementation • Helpful hints • Follow general ADMT guidance; pre-coordinate deviations from general guidance • Be ready to perform generic modeling of ALL sources • Use MAXIFILE option with source groups

  22. Example (2) Implementation • First conduct generic modeling • Use 1 lb/hr for each source/source group • Use 1 model input file • Use 1 PLOTFILE • Use 1 averaging time (1-hour or annual)

  23. Example (2) Implementation • Import PLOTFILE into a spreadsheet • Select fixed record length option • Parse the columns properly • Start on first row of data, skip the header • Sort data in spreadsheet • Sort by source group, x, y • Delete all header lines

  24. Example (2) Implementation • Import spreadsheet into database program • Create a table of the spreadsheet data • Run query to reformat data • Export query results into another spreadsheet • Results are the unit concentrations

  25. Example (2) Implementation

  26. Example (2) Implementation • Determine maximum unit concentrations • Use MAX function for each source group • Determine worst case source • Can apply E/ESL for that source, maybe • Can use for generic method 1 • If you pass, you’re done

  27. Example (2) Implementation

  28. Example (2) Implementation • Determine worst case scenario • Provide data from generic modeling • Analyze data from generic modeling • Specify the operational conditions • Propose physical or operational limits

  29. Example (2) Implementation

  30. Example (2) Implementation

  31. Example (2) Implementation • Refine with generic method 2 • Create worksheet with emission rates • List pollutant • List ESL • List emission rate by source group

  32. Example (2) Implementation

  33. Example (2) Implementation • Refine with generic method 2 • Apply unit concentration to E/ESL • For each source group • Sum contributions from all source groups • Determine the maximum • Results are in multiples of the ESL

  34. Example (2) Implementation

  35. Example (2) Implementation • Further Refinement • Pollutant specific modeling • Use the MAXIFILE option • For the ALL source group • For culpable source groups • Use an appropriate threshold

  36. Example (2) Implementation • Further Refinement • Adjusting hours of exceedance • Consider hours of culpable sources • If hours fewer than hours of exceedances • Scale based on hours if operating hours are frequent • Consider operation schedule • Daytime only or nighttime only • Hours between activities

  37. Summary • Be clear on concepts discussed earlier • Ask questions if you are unclear or unsure • Follow ADMT guidance • Document everything you did • Minimize the modeling and modeling files

  38. Questions

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