Two 72 ft tall stacks were installed.
Each stack was designed to meet air velocity requirements.
The installed stacks cost less than steel.
Composite ducting moves air toward the stacks.The 96 inch (2.4 m) diameter, 72 ft (22 m) high stacks were designed, built and installed by odour control specialist Bay Products Inc. The company manufactured the stacks and odour control system components using corrosion-resistant and fire-retardant Vipel K022 bisphenol A epoxy vinyl ester from AOC. The stacks were manufactured by the filament winding process in which continuous fibreglass roving was encapsulated in the Vipel resin.
The stacks were a natural extension of an odour control system designed to move 120 000 ft3 (3400 m3) per minute of air. The system’s 100 inch (2.54 m) diameter, filament wound composite ducting and open-moulded composite covers and dampers were also made with AOC's Vipel K022 vinyl ester resin.
Vipel K022 resin resists the highly acidic internal operating environment of the anti-odour system where pH levels can get as low as 2. Furthermore, with minimal synergist addition, the resin meets ASTM E84 Class 1 flame spread and smoke requirements.
Composites chosen over steel
To meet the specification for freestanding stacks without guy lines, the Camden County Municipal Authority initially selected stacks made of steel. A thin inner liner of fibre reinforced polymer (FRP) composite was to be added to protect the metal from corrosive exhausts. But Director of Design and Manufacturing Jeff Jones pointed out how all-composite stacks could do the job better, and 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.”
To help meet the freestanding requirement the stack cylinder wall was manufactured to be well over 1 inch (25.4 cm) 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’s Eric Stuck worked with us to develop a resin formulation that keeps exotherm down until the resin was fully cured.”
With corporate headquarters located in Stateline, Nevada, Bay Products Inc specialises in the design and manufacture of equipment for the air and water industries, including odour control systems, ductwork, and chemical storage tanks. The Bay Products manufacturing facility is located in central Texas.