By Brian Wheeler, Associate Editor
With the summer heat straining their installed capacity in the southeast region of the United States and forcing out-of–market energy purchases, Southwestern Electric Power Co. (SWEPCO), a unit of American Electric Power, saw a need to bring additional capacity online.
Using existing natural gas pipelines and electric transmission lines, SWEPCO in 2006 made plans to build the 523 MW J. Lamar Stall gas-fired combined-cycle unit adjacent to the oldest plant in the SWEPCO system, the Arsenal Hill Power Plant in Shreveport, La. Along with the established pipeline and transmission infrastructure, SWEPCO also owned two Siemens-Westinghouse 501FD2 gas turbines, a GE D-11 reheat condensing steam turbine and a modified Thermal Engineering International condenser.
The 523 MW J. Lamar Stall Unit in Shreveport, La. Photo courtesy AEP
“We had the material, needed the capacity and needed it to be brought on rather quickly,” said Bill Sigmon, senior vice president of engineering and construction for American Electric Power. “All these together dictated that we went with gas.”
A joint partnership between Sargent & Lundy and TIC, The Industrial Company, known as JSL Partners, built the Stall Unitin 27 months. It was put into commercial service almost six weeks ahead of the guaranteed completion date. Although construction of the plant proceeded well, Sigmon said several challenges emerged that the engineering, construction and management teams had to overcome.
First, the location at the Arsenal Hill site within Shreveport’s city limits left eight acres of available land for the new plant. The small site, hemmed in by a Union Pacific railroad line and a city fire department, left little room for lay-down space for the necessary equipment.
“Between the rail line, the fire station and the plant, it was cramped,” said Sigmon.
To remedy the problem, land was acquired about two miles from the Stall plant site and equipment was trucked in on an as-needed basis. Due to space issues, the new unit does not have an in-plant control room. Instead, the Arsenal Hill Unit 5 main control room was upgraded and now serves as the control room for the Stall plant as well.
A second challenge that delayed construction for four months was a train accident that destroyed two Nooter/Eriksen HRSG piping modules as they were being delivered. The first shipment had already been received in 2009 and the accident left Nooter/Eriksen scrambling to get the modules to the site. The delay forced the construction team to reserve areas for the crane and resulted in construction delays across the project.
“It was the biggest hurdle we had to overcome,” said Dan Gullaksen, vice president of fossil power for Sargent & Lundy.
Located in the Gulf Coast region, the construction site also felt the remnants of two hurricanes within a few weeks of each other. Hurricanes Gustav and Ike both shut down the site. Although the construction schedule was affected, no damage occurred to existing infrastructure.
After addressing these issues, the EPC contractor integrated new equipment with the components that AEP already owned and the gas-fired power plant began commercial operations on June 16, 2010. Through October the plant had a 77 percent capacity factor and had generated roughly 1.2 million MWh.
“During summer peaks in the Shreveport area this plant is going to have pretty high capacity factor,” said Sigmon.
Operating with low NOX burners and selective catalytic reduction, Gullaksen said engineers were able to remove 90 percent of NOX. The older 501FD2 combustion turbines that emitted 25 ppm of NOX have been controlled to 2.5 ppm. And the CO2 emissions from the burner itself are roughly 10 ppm.
Measured in terms of output and heat rate the plant operates better than the design basis. The original output design was 520 MW and the plant is operating currently at 523 MW. The original heat rate specifications were for a little over 7,000 Btu/kWh, but the plant tested at 6,800 Btu/kWh.
“Both of these key performance parameters we were able to achieve and beat,” said Sigmon.
Now in full operation, the facility was constructed for about $800/kW. Sigmon said that if a similar combined-cycle plant were built today it would cost significantly more.More Power Engineering Issue Articles
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