What began as scheduled maintenance turned into that plus preventive efforts at JEA’s Brandy Branch Generating Station.
When a natural gas combustion turbine was disassembled for its 24,000-hour maintenance and overhaul, cracks were discovered in the rotors in one of the units, said Mike Brost, vice president and general manager of electric systems.
That meant the rotor assembly had to be removed and sent for repair to General Electric’s facility in Greenville, S.C.
The unit operates at 2,000 degrees and the turbines rotate 3,600 times per minute to produce about 500 megawatts of electricity.
“It’s like a jet engine mounted on a foundation. This is a common issue after 12 years of operation,” said Brost.
The utility’s board of directors approved Tuesday transfer of $12.86 million to the electric system’s capital budget for the work.
Located in West Jacksonville near Baldwin, Brandy Branch began operation in 2001 with three combustion turbines that burn natural gas.
The performance and efficiency of the plant were enhanced in 2005 by converting two of the turbines into combined cycle units with the addition of steam turbines.
The gas turbine generates electricity by burning natural gas while the steam turbine generates electricity using waste heat from the gas turbine.
Heat that previously was vented through the plant’s exhaust stack is used to convert water into steam, which drives a turbine that generates electricity with no additional fuel cost.
Brandy Branch is one of three natural gas combustion turbine facilities operated by the utility.
The generators at the Kennedy Generating Station along Talleyrand Avenue and the Greenland Energy Center in South Jacksonville are unmanned and controlled at Brandy Branch.
The overhaul was scheduled after winter and before summer to have as little impact on JEA’s electric generating capacity as possible.
Brandy Branch accounts for about 15 percent of the utility’s electric capacity, Brost said.
Originally scheduled to be complete by April 15, the additional repair added a few weeks to the station being off-line.
“We should be back up this week,” said Brost.
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