The Florida Department of Environmental Protection on Oct. 5 approved air permitting that would allow Tampa Electric to sharply ramp up the amount of regular natural gas it fires in the Polk Power Station (PPS) Unit 1, which is an integrated gasification combined-cycle unit built in the 1990s that fires syngas derived from coal and petroleum coke.
The existing PPS Unit 1 a 260-MW combined cycle combustion turbine which fires syngas or natural gas. In addition, the PPS facility has: two nominal 165-MW simple cycle gas turbines firing either natural gas or No. 2 fuel oil which comprise Units 2 and 3; and two nominal 165-MW simple cycle gas turbines firing only natural gas which comprise Units 4 and 5. Units 2-5 are in the process of being converted from simple cycle turbine generators to a “4-on-1” combined cycle configuration with four duct-fired heat recovery steam generators (HRSGs), one steam electric generator, a mechanical draft cooling tower, and other ancillary equipment.
The permit approved Oct. 5 increases the hours of operation that the PPS Unit 1 is authorized to fire natural gas only from 876 hours to 3,000 hours per year. No physical changes were proposed to Unit 1 to accommodate the increased use of natural gas. This IGCC includes a General Electric Model Number 7FA unit that is already capable of firing both syngas and natural gas.
Notable is that the combined-cycle conversion of the simple-cycle units (Units 2-5) at Polk will be completed in January 2017, said Tampa Electric officials in Sept. 1 fuel testimony filed at the Florida Public Service Commission. Penelope A. Rusk, the utility’s Manager, Rates in the Regulatory Affairs Department, when asked if there are any significant events reflected in the calculation of the 2017 fuel and purchased power and capacity cost recovery projections, replied: “Yes, the company’s highly efficient Polk combined cycle (‘CC’) unit is anticipated to begin commercial service in January 2017. The unit will provide reliable and efficient natural gas-fired generation for customers. As stated in the testimony of Tampa Electric witness J. Brent Caldwell, the company did not require new natural gas supply or transportation agreements to serve this unit, due to the flexibility of the company’s existing natural gas supply portfolio.”