The Florida Department of Environmental Protection is reviewing an April 29 application from Tampa Electric for an air permit change allowing more use of regular natural gas, which would displace some use of syngas from an on-site gasifier, at the Unit 1 of the Polk Power Station (PPS).
The Unit 1 integrated gasification combined cycle facility was built in the 1990s with funding help from a U.S. Department of Energy clean coal demonstration program. The unit has operated largely on petroleum coke in recent years that is (along with any coal used) trucked from Tampa Electric’s Big Bend power plant on Tampa Bay. Big Bend takes in coal and petcoke either by ship or rail.
The Polk plant consists of one nominal 260-MW combined-cycle gas turbine facility (Unit 1) and four simple-cycle combustion turbines (CTs). Tampa Electric is in the process of modifying the four simple-cycle CTs to a four-on-one, combined-cycle configuration with the installation of four new heat recovery steam generators (HRSGs), one steam electric generator, a mechanical draft cooling tower, and other ancillary equipment.
Unit 1 is currently authorized to combust syngas only, syngas with natural gas augmentation, and pipeline-quality natural gas only. The current Title V air operation permit authorizes Unit 1 to operate continuously, i.e. 8,760 hours per year (hr/yr) while combusting syngas or while combusting syngas with natural gas augmentation. Unit 1 is also authorized to operate up to a 10% annual capacity factor (876 hr/yr) while combusting natural gas only.
Said the April 29 application: “Tampa Electric wishes to increase the maximum annual hours of operation for EU 001 while combusting natural gas only from 876 hr/yr to 3,000 hr/yr. This will provide PPS with greater operational flexibility. This increase in maximum hours of natural gas-fired operation will result in an increase in annual nitrogen oxides (NOx) emissions since the hourly NOx emissions rate is slightly higher when combusting natural gas as opposed to combusting syngas. The hourly emissions rate for all other pollutants is the same whether combusting syngas or natural gas; therefore, there will be no increase in annual emissions of any other pollutant. The increase in annual NOx emissions will be greater than the NOx Prevention of Significant Deterioration (PSD) significant emissions rate (SER) and thus will be considered a major modification under PSD regulations.”