POWER-GEN International and NUCLEAR POWER International offered multiple technical tours again this year to begin the conference and exhibition in Las Vegas. NV Energy, the host utility for POWER-GEN International and NUCLEAR POWER International, opened its doors to the Harry Allen Generating Station to 35 show and conference attendees on Monday afternoon, one day after completing a week-long maintenance outage.
Located 25 miles north of Las Vegas, the natural gas-fired Harry Allen station was originally built as a 72 MW simple-cycle power plant to provide electricity during peak demand times in southern Nevada. The original 72 MW General Electric 7EA combustion turbine was completed in 1995. In 2006, a similar unit was added and includes a DLN1+ dry low-NOx combustion system.
In November 2007, NV Energy, which serves a 44,424 -square-mile service territory that includes approximately 2.4 million citizens of Nevada and nearly 40 million tourists annually, began construction on a 484 MW combined-cycle addition. Four years later, in May 2011, NV Energy completed the combined-cycle system at the Harry Allen station that includes two GE 7FA+e combustion turbines and a recycled exhaust system, with two heat recovery steam generators that capture waste heat from the turbines, to produce steam for a GE D11 steam turbine to produce additional power. With the addition, NV Energy said it can now meet roughly 80 percent of the peak energy needs of southern Nevada.
Brian Paetzold, assistant regional director for NV Energy, said the combined-cycle system allows the utility to use what would be wasted energy and the plant generates roughly 50 percent more power due to the system.
The Shaw Group provided engineering procurement and construction services, while GE supplied the combustion and steam turbine equipment and Vogt the heat recovery steam generator.
In a time when environmental concerns are a top priority for power plant operators, the Harry Allen station uses an Emerson Ovation control system. With this system, the plant shuts down if it is not operating in compliance, in regards to emissions.
"Emissions monitoring is critical,” said Paetzold.
Currently, the Harry Allen station emits about 1.5 ppm of NOx.
The Harry Allen plant also utilizes a dry-cooling system that allows it to produce electricity using only 6 percent of the water required by similar facilities and other technology that recycles 75 percent of the water used. And utilizing a Siemens water treatment plant, Paetzold said the Harry Allen plant has a 90 percent water recovery rate. The combined-cycle units at the Harry Allen station use a six-story-high dry cooling system, similar to that of a car radiator. Thirty-six fans, powered by 250 horsepower motors, are used to condense the steam back into water to be reused at the plant. And although expensive, Paetzold said due to water limitations in the area, air-cooled condensers are a must at Harry Allen.