Composite stacks save taxpayers money

An alternative specification for two new towering exhaust stacks not only significantly reduced initial costs for the Camden County Municipal Authority. The durability and superior corrosion resistance of the stacks’ all-composite design will also essentially eliminate maintenance costs at a Camden, New Jersey, wastewater facility for years to come.

The 96-inch diameter by 72-feet tall (244 centimeters by 22 meters) stacks were designed, built and installed by odor control specialist ECS Environmental Solutions (ECS). ECS made the stacks and odor control system components with corrosion-resistant and fire-retardant Vipel K022 bisphenol A epoxy vinyl ester from AOC.

To meet the specification for freestanding stacks without guy lines, the Authority initially selected stacks made of steel. A thin inner liner of fiber-reinforced polymer (FRP) composite was to be added to protect the metal from corrosive exhausts. Jeff Jones, President of ECS. pointed out how all-composite stacks could do the job better for less.

“We explained how composite can be engineered to be freestanding and to withstand the same forces that the steel stacks were designed for. In addition, the solid composite ensures superior corrosion resistance and a Class 1 fire rating throughout the entire structure - inside and out.”

The stacks were manufactured by the filament winding process in which continuous fiberglass roving is encapsulated in the Vipel® resin. One design parameter that helped each composite stack meet the free-standing requirement was to manufacture the cylinder wall to be well over 1-inch (25.4-centimeter) thick.

Building a composite that thick can compromise laminate integrity because of excess exotherm, the heat generated when a composite resin cures into a structural solid. “Controlled exotherm was another benefit of using the AOC material. AOC worked with us to develop a resin formulation that keeps exotherm down until the resin was fully cured.”

120,000 CFM System

Suggesting the all-composite stacks drew upon ECS’reputation for offering superior solutions with high value. “Like everyone else today, municipal authorities are looking for ways to trim costs. We offer a variety of odor control systems to help meet performance requirements in the most cost-effective way.”

The stacks were a natural extension of an odor control system designed to move 120,000 cubic feet (3,400 cubic meters) per minute of air. The system’s 100-inch (254-centimeter) diameter, filament wound composite ducting and open-molded composite covers and dampers were also made in the ECS facility with Vipel K022 vinyl ester.

Vipel K022 resin resists the highly acidic internal operating environment of the anti-odor system where pH levels can get as low as 2. Furthermore, with minimal synergist addition, the resin meets ASTM E84 Class 1 flame spread requirements.

About Engineered Composite Systems

With corporate headquarters located in Stateline, Nevada, Engineered Composite Systems specializesin the design, manufacture and sales of equipment for the air and water industries. The ECS manufacturing facility is located in central Texas. ECS is the largest odor control system supplier in North America. Product offerings include a full line of odor control sys-tems, such as carbon absorbers, chemical scrubbers, several different biological systems, ductwork, dampers, chemical storage tanks and odor control covers. For more information go to www.ecs-env.com.

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