Hyperbolic cooling towers have a distinctive shape, but that form is subordinate to function—natural-draft cooling is cheaper than mechanical-draft cooling. The lower operating costs are offset to some degree by the higher cost of protecting internal tower surfaces from swings in humidity that foster corrosion damage. Learn how one utility added cathodic protection when it repaired its corroded hyperbolic tower, giving it a new lease on life.
Control pollution and slagging on a shoestring / Keeping HRSGs young, cool, and clean / Natural air conditioning
The challenge for suppliers of aftermarket turbine blades is that their starting point is an existing blade and nothing else. There are no CAD models, drawings, measurements, tolerances, or inspection data associated with it. However, thanks to the latest in computer tools, a blade now can be digitally recreated to exact specifications and built using the latest design and manufacturing practices. Here’s an inside look at how turbine blades are captured, reconstructed, inspected, and remade to be better than the originals.
Part I of this three-part series (POWER, October 2006) explored the negative impacts of sulfur trioxide (SO3) on the operations and maintenance of back-end plant equipment. Part II (February 2007) listed and quantified the likely and potential benefits of limiting the concentration of SO3 in flue gas to 3 ppm at the entrance to the air heater. This final part describes the characteristics of an optimal SO3 removal technology and details the operating experience of a patented process that has worked successfully at a half-dozen plants for up to three years.
Want some good news about your predictive maintenance program for a change? A recent research report by the Aberdeen Group found the electric utility industry benchmarks exceptionally well against other industries in its PDM practices. In fact, the research found that best-in-class companies outperformed industry peers in improving asset availability by up to a three-to-one margin. In a web exclusive, the Aberdeen Group has provided its report for download from powermag.com as a service to our readers.
Doctors and engineers realize that solving a health problem is better done by identifying and eliminating its cause than by treating its symptoms. For machinery, the class of multidisciplinary methods known as root cause analysis (RCA) is an important tool for addressing chronic reliability problems. But RCA often is improperly applied to lubrication-related problems. Read on to learn how to use the technique correctly.
The term "water hammer" encompasses a handful of hydraulic and thermohydraulic mechanisms. They include water hammer in steam and water piping, water piston, water induction, flash condensation and evaporation, and shock waves generated by transonic flow. All can lead to failures of steam and water cycle components and put plant operators and workers at risk. Proper design and O&M practices can keep water hammer and similar phenomena under control.
The critical subset / Aging workforce challenges / Tighter tolerances in retrofits / Writing sensible start-up and shutdown procedures
A century ago, boiler explosions were an all-too-familiar event. But with the universal adoption of the ASME Boiler and Pressure Vessel Codes in 1914, explosions caused by poor design or manufacturing became relics of history. Electrical classification codes had the same effect on safety. This article explains how designers and operators practically apply those standards. Code details and samples of area classification drawings for a gas turbine plant are included in an online supplement (see end of story).
Dominion Generation (DG) has installed selective catalytic reduction (SCR) systems on many of the large coal-fired generating units it operates. The catalyst used has an SO2 to SO3 oxidation rate of about 1%, which roughly doubles the SO3 concentration at the outlet of the boiler economizers. The magnitude of the increase was proportional to the […]