Date: December 16, 2011 Subject: Conversion of EGU MACT Emissions Da ta for Two Integrated Gasification Combined Cycle (IGCC) Units to the Same Basis

From: Stephen Boone (RTI International)

To: Bill Maxwell OAQPS/SPPD/ESG (D243-01) U.S. Environmental Protection Agency Research Triangle Park, NC 27711

Public comments on the EGU MACT proposal noted that the two IGCC units that provided emissions data under the Information Co llection Request (ICR), reported emission rates using different basis, and claimed that thes e data were not comparable. RTI conducted an analysis that confirmed the concerns of th e commenters and developed a methodology for conversion of the emissions data to the same basis. The emissions data from Tampa Electric Company’s (TECO’s) Polk IGCC facility was base d on an estimate of the heat content in the solid fuels being fed into the reaction vessel that produces the syngas, while the emissions data for Duke Energy’s Wabash IGCC facility was repo rted based on the heat content in the syngas exiting the reaction vessel. Si nce the affected source under the MACT standard is the combustion unit (i.e., the combustion turbine for an IGCC facility), the heat input from the syngas to the combustion turbine was used as the common basis for both sources. Available CEMS data from TECO’s Polk IGCC facility were converted from a solid fuel heat input basis (to the reactor) to a syngas heat input basis (to the combustion tu rbine). Since the Wabash data was submitted on a basis consistent with the rule, no conversion of the Wabash data was
necessary. The available CEMS data included 30 days of operating data submitted from the Wabash facility that indicated the heat rate varied from 10.7 MMBtu per gross MW at 90 percent to 10.1 MMBtu/MWg at 100 percent of capacity. Similarl y, the 30 days of operating data submitted by TECO for the Polk facility indicated that it has a slightly better heat rate than Wabash (i.e., 10.3 MMBtu/MWg at 90 percent of capacity and 9. 9 MMBtu/MWg at 100 percent of capacity). The attached file includes a spreadsheet show ing the heat rate derivations for conversion of the lb/MMBtu emission factors to a lb/MWg basis. There is also a spreadsheet with calculations that convert the lb /MMBtu emission rates reported under the ICR for TECO based on an oxygen-based F-factor of 9780 for bituminous coal to a CO2 based calculation using the Ffactor for syngas used in the TECO data acquisition and handling system. The top section of the filterable particul ate (fPM) calculations spreadsheet shows the revised calculations (based on Equation 19-6 of Method 19) necessary to apply the CO 2 based F factor to the stack testers sampling data. The bottom of the spreadsheet includes a QA measure, where the data reported by the stack tester (b ased on the oxygen based F-factor for bituminous coal) were re-entered into Equation 19-1 to conf irm the units of measure and the wet or dry basis of the submitted stack testing data. Upon verifi cation of the units of measure by obtaining thesame results as the stack tester, these same parameters were utilizedin Equation 19-6 to complete the carbon-based F-factor calculations for syngas combustion. In the preceding manner both the heat input based emission data and the output based emissions data for TECO’s Polk IGCC unit were c onverted to the same basis as that submitted for Wabash. The results from this analysis indi cated that the reported lb/MMBtu emission rates on an O 2 basis for bituminous coal for TECO’s Polk faci lity needed to be in creased by a factor of 1.16 to be consistent with the reported values for Wabash (i.e., both sources emissions on a lb/MMBtu basis reflecting the heat input to the combustion turbine.)