Safeguarding coal-handling assets;
Giant wind turbine hard to bear
Safeguarding coal-handling assets;
First live superconducting cable / Biggest CO2 storage project / Largest hydrogen-fueled plants / Record run for fuel cell cogen system / Largest PV plant still in Bavaria / Luz returns to U.S. / POWER digest
Concerns about global climate change have prompted interest in reducing or eliminating the carbon dioxide (CO2) emissions of fossil fuel-fired power plants. Here’s a guide to the technology and economics of three CO2 capture methods: postcombustion separation of CO2 from flue gas (applicable to existing plants), and oxygen-fired combustion and precombustion capture (suitable for new coal-fired capacity, including IGCC plants).
For some gencos, the dearth of operating experience for integrated gasification combined-cycle plants adds too much uncertainty to the risk/reward equation for new-capacity technology options. For others, the possibility of being able to comply with air pollution limits as far out as 2018, as well as to meet all-but-certain CO2 caps, makes IGCC well worth investing in—now.
Slagging and fouling of furnaces and boilers’ convective pass top the list of costly coal plant O&M problems. Although sootblowing is a tried and true solution, running sootblowers too often can erode boiler tubes. Lehigh University’s Energy Research Center has developed an "expert" sootblowing system that has outperformed experienced operators’ "seat of their pants" sootblowing procedures on two head-to-head field tests.
Fuel flexibility isn’t free. Whether you’re equipping a new power plant to burn more than one type of coal or retrofitting an existing plant to handle coal blends, you’ll have to spend time and money to ensure that all three functions performed by its coal-handling system—unloading, stockout, and reclaim—are up to the task. The first half of this article lays out the available options for configuring each subsystem to support blending. The second half describes, in words and pictures, how 12 power plants—both new and old—address the issue.
The O&M staff of AES Westover Station wisely took a holistic approach to optimizing combustion within Unit 8’s boiler in order to reduce its NOx emissions while maintaining acceptable levels of carbon-in-ash content. The results of major modifications—centered on the addition of a fan-boosted overfire air system—were a 60% reduction in NOx levels, improved unit reliability, and a project payback period measured in months rather than years. As this project proved, the whole is more than the sum of its parts.
Point Aconi’s circulating fluidized-bed boiler experienced erosion, corrosion, and fouling problems from the day it went on-line in 1993. After several frustrating years of unreliable operation, in late 1999, Nova Scotia Power discovered the right combination of engineering and fuel modifications. Today, after a switch to 80% petroleum coke and major boiler modifications, Point Aconi’s output exceeds its original nameplate rating. For having the vision and fortitude to plan and execute a multiyear, $20 million project to revitalize North America’s first in-service utility CFB boiler, Nova Scotia Power’s Point Aconi plant is the well-deserved winner of POWER magazine’s 2006 Marmaduke Award for excellence in O&M.
It’s said that pioneers take the arrows. In the case of Springerville Unit 3—a 418-MW (net) expansion of a Tucson Electric Power facility in Arizona and the first pulverized coal–fired unit built in the U.S. in more than a decade—the arrows were many. Although Tri-State (the developer), Tucson Electric (the host), and Bechtel Power (the EPC contractor) were wounded by delayed deliveries of major equipment, bankruptcy of a major supplier, and a labor shortage, the companies showed their pioneering spirit and completed the project ahead of schedule. For ushering in a new generation of clean and desperately needed baseload capacity, Springerville Unit 3 is POWER magazine’s 2006 Plant of the Year.
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