By Brian Wheeler
About 50 miles northeast of Louisville, Ky., in a rural district on about 2,200 acres along the banks of the Ohio River is the Trimble County power station. During the 2012 COAL-GEN Conference and Exhibition in Louisville on Aug. 14, about 20 COAL-GEN attendees visited the Trimble County plant. Louisville Gas and Electric (LG&E) and Kentucky Utilities (KU), both PPL companies, own and operate the plant. The Trimble County station, PPL and LG&E’s newest power plant, is home to two large coal-fired units and six combustion turbines. The plant’s two coal-fired units, TC1 and TC2, are also jointly owned by the Illinois Municipal Electric Agency and the Indiana Municipal Power Authority.
|The Trimble County power plant is home to eight generating units, six gas-fired peaking units and two large coal-fired units.|
The station is home to six GE 7FA simple-cycle, natural gas-fired combustion turbines, used primarily for peaking. Gas-fired Units 5 and 6 entered service in the summer of 2002, with Units 7 through 10 following in the summer of 2004.
The units are fueled by a six-mile gas pipeline that LG&E also owns, operates and maintains. Since the gas-fired units are used for peaking, “starting reliability is very important,” said Trimble County plant manager Tom Crutcher. The units have a greater than 95 percent starting reliability.
But the focus of the tour was the coal-fired units.
In commercial operation since 1990, TC1 is a subcritical unit that uses Eastern Bituminous coal to generate about 514 MW. Even though TC1 is a reliable unit that LG&E is proud of, the star of the tour seemed to be TC2, LG&E’s newest unit. TC2 is a supercritical unit that generates 760 MW firing on a blend of Eastern Bituminous and Western Sub-bituminous (PRB) coal.
After receiving permission from the Kentucky Public Service Commission in 2005, LG&E broke ground on the new coal-fired unit in August 2006. That year, LG&E and KU received a $125 million tax credit from the U.S. Internal Revenue Service, made available through the 2005 Energy Policy Act, for the construction of TC2, a savings that is passed on to customers. To receive the credit, LG&E had to meet the IRS’s criteria, which included achieving a 99 percent SO2 and 90 percent mercury removal.
Also in 2006, LG&E selected Bechtel Power Corp. to design and build TC2. At peak construction, over 3,000 workers were constructing TC2 which required about 11.5 million man hours. Prior to the construction of TC2, the Trimble County plant employed 92 full-time employees. When the new unit is commercially operational, 156 full-time employees will be on-site. The unit is now in an ‘interim operation’ mode as the operators deal with problem with the combustion system, according to Crutcher. While the plant is not fully commissioned, Crutcher said the power is dispatchable.
What caught the eye of COAL-GEN 2012 attendees was the uniqueness of the plant along with the amount of environmental controls on TC2.
“Not many units have the arrangement of Unit 2,” said Crutcher.
Twenty-five percent of the total cost of TC2 was spent on environmental-related equipment. TC2, as well as TC1, are equipped with low NOX burners, selective catalytic reduction, which removes about 90 percent of its inlet NOX, dry electrostatic precipitators and wet limestone flue gas de-sulfurization.
TC2 is also equipped with powdered activation carbon injection and a pulse jet fabric filter for mercury removal, as well as a wet ESP for fine acid mist removal.
TC2 was built with a Hitachi steam turbine and generator, as well as a Hitachi SCR system. Doosan-Babcock supplied the boiler.
Wheelabrator Air Pollution Control, a division of Siemens Power Generaiton, designed and fabricated portions of the air quality control system, such as the WFGD, the wet ESP and the carbon injection system for mercury control.
Crutcher, who has worked at the Trimble County plant since 1998, said a lot of construction activity has been taking place over the past 10 years as the utility upgraded Unit 1 and built Unit 2.
“About four years went by from sticking the shovel into the ground to synchronizations,” he said.
Safety at Trimble County is at the fore-front. The plant has not had an Occupational Safety and Health Administration (OSHA) reportable incident or lost time injury in about three years.
“We are looking for a lot of years of operation out of Trimble County,” said Crutcher.