A major milestone in the development of Advanced Ultra-Supercritical Steam power plants (A-USC) was recently achieved with the successful completion of more than 17,000 hours of operation of the world’s highest operating-temperature steam loop at Plant Barry Unit 4.
The plant is located in Bucks, Alabama, and is operated by Southern Company subsidiary Alabama Power, which, together with the Southern Company research and development team, was instrumental in this achievement.
During the trials, the steam loop maintained operation at temperatures exceeding 1,400 degrees F (760 degrees C). The loop contained a unique combination of 94 specimens with eight different superalloys and three different surface coatings that enabled it to withstand the high A-USC temperatures within the coal-fired boiler. Upon removal, the components appeared in good condition and retained their original mechanical integrity. The components are now undergoing an extensive corrosion, oxidation and material properties examination at Alstom’s Material Technology Center in Chattanooga, Tennessee.
This successful trial is an important contribution in the development and verification of A-USC power plants and improves the confidence in commercial deployment of these higher operating temperature plants that are 25 percent more efficient than today’s fleet average and 10 percent more efficient than the most advanced current state-of-the-art steam plants.
The steam loop was designed and overseen by Alstom’s Boiler research and development group in Windsor, Connecticut. It was fabricated by Alstom’s Factory in Chattanooga, Tennessee and installed at Plant Barry in December 2011. It is part of the U.S. Department of Energy’s National Energy Technology Laboratory and Ohio Coal Development Office A-USC Materials Consortium which is validating super alloy materials for use at the extreme conditions of A-USC plants.