Utility cuts piping costsin SNCR installation
Delmarva Power & Light Co., Wilmington, Del., and other utilities in the Northeast Ozone Transport Region on the east coast are facing the prospect of additional capital investments to meet the requirements of the Clean Air Act. The Environmental Protection Agency, through the actions of individual states, has mandated installation of available control technology. Delmarva was required to reduce its NOx emissions by May 31, 1995. Moreover, there was speculation that the state might toughen the legislation, reducing the emission rate even further.
The company faced the issue of finding a technology that would not only reduce emissions to current standards, but which would position it to meet pending regulations. The utility decided to install a relatively new technology called selective non-catalytic reduction (SNCR). The SNCR system was installed on Delmarva`s 80-MW Edge Moor Unit 3, a coal-fired boiler. The system requires injection of urea-based NOx Out into the combustion zone of the boiler to form carbon monoxide, nitrogen and water vapor. Research Cottrell of Branchburg, N.J., designed and supplied the equipment for the system which uses 15 injectors on three elevations of the boiler. In the process of complying with regulatory emission levels, Delmarva faced another big issue–cost.
“The urea is stored in a 25,000-gallon tank and conveyed to the boiler by piping,” said Mike Zoccola, project engineer for Delmarva. “The original specs called for welded Schedule 40 stainless steel which is very expensive. Instead we used light-wall stainless steel piping and installed it with Victaulic Co.`s new Pressfit system. It requires no welding, threading or flanges, just an electric pressing tool.”
The system is designed for joining a variety of sizes of stainless steel pipe, ranging from 0.75 to 2 inches, with Type 316/316L stainless steel couplings and fittings. Assembly involves cutting the pipe to size, marking it, inserting it into a coupling and pressing the coupling with a special electric, electro-hydraulic or hydraulic tool.
The couplings incorporate synthetic rubber O-ring seals and internal stops for uniform takeout from pipe dimensions. The jaws of the assembly tool engage the circumference of the coupling and compress it to indent the pipe providing a mechanical union. In the process, the tool also compresses the