The Florida Department of Environmental Protection on July 27 put out for comment a draft air permit approval that would allow Florida Power & Light to undertake a major revamp at its Fort Myers power plant.
The Fort Myers Plant includes one bank of 12 simple cycle gas turbine units (GT1 through GT12). GT Units 1 through 12 began operation in May 1974. Each GT, used for peaking purposes, has a nominal gross capacity of 63 MWs. In addition to units GT1 through GT12, the Fort Myers Plant consists of six combined-cycle generating units (Units 2A through 2F) which began operation between 2000 and 2001, and two modern simple cycle combustion turbines (Units 3A and 3B) which began operation in 2003.
Each combined-cycle unit (2A through 2F) consists of one combustion turbine (CT) which exhausts through a separate heat recovery steam generator (HRSG). Each HRSG converts the heat from the CT exhaust into steam. The steam produced from the HRSG drives a steam turbine electrical generator. Each combined-cycle unit has a net summer continuous capability of 250 MW, which includes 170 MW from the CT generator and 80 MW from the associated steam turbine generator.
The two simple cycle CTs (3A and 3B) are 170-MW General Electric MS7241FA peaking units, with dry low-NOX combustors.
This current application is for a project to replace ten of the 12 simple cycle gas turbine units with two modern combustion turbines. The two existing GTs that will remain will be used for black start capability and for generation. Like the turbines they are to replace, the two new turbines will be used as peaking units. FPL has chosen the GE 7F.05 turbine for this project.
This project involves construction of two new GE 7F.05 combustion turbines with nominal generating capacity of 200 MW each. The maximum heat input for each turbine will be approximately 2,262.4 million British thermal units (MMBtu)/hr with natural gas, and 2,353.7 MMBtu/hr on fuel oil.
“These turbines are intended to be run as peaking units; therefore, they will be run primarily during periods of high electrical demand,” said a DEP technical review document. “FPL has requested a permitted limit of 3,390 hr/yr of operation for each of the turbines, of which up to 500 hr/yr may be fueled by ultra-low-sulfur distillate (ULSD) oil. The primary fuel for the turbines will be natural gas. Actual usage of these turbines will likely be considerably less than these requested permitted hours. For example, in their 2015 Ten Year Site Plan to the Florida Public Service Commission, FPL estimated a capacity factor of approximately 3% (~300 hr/yr) for these turbines.”
The DEP added that these turbines will incorporate inlet air cooling consisting of evaporative cooling and wet compression. In this arrangement, water from an evaporative cooling medium cools the inlet air stream. This results in a cooler, denser stream of air, which allows for a greater throughput of air to the turbines and additional power output. Wet compression also increases power output by increasing mass flow through the introduction of water droplets near the compressor inlet.
“FPL intends to keep two of the 12 existing 1970s-vintage gas turbines available for black start capability and generation,” the DEP added. “Currently, these turbines have no restrictions on their hours of operation. FPL has requested that the hours of operation for these two turbines remain unrestricted.”
These new GE 7F.05 turbines are the same model proposed for a similar project at the FPL Lauderdale Plant in Broward County. FPL has requested that the permit for this project at Fort Myers be as consistent as possible with the permit for the project at the Lauderdale facility. The DEP went out for comment earlier in July on the Lauderdale project’s air permit.