The industry leader in FGD systems is Ershigs, headquartered in Bellingham, Washington. The most common type of pollution control equipment produced by Ershigs is wet FGD scrubber systems with standard spray towers, according to Chaun Trenary, VP Sales & Marketing. Ershigs is one of only a handful of companies capable of doing field winding of large scrubber tanks and vessels. Sizing is based on the gas flow of the system. The largest wet FGD scrubber built by the company was 119 feet in diameter and about 70 feet tall – a Chiyoda CT-121 jet bubbling reactor.
Most processers limit their filament winding to the shop rather than investing in the large winding equipment needed for field production, which requires the equipment to be trucked to the site and assembled inside a temporary building. An enclosure is needed to control the production environment. The winders are carousel-type vertical winders. Chimney liners can be wound vertically or horizontally in the field, notes Trenary. Typically, continuous strand E glass or ECR glass is used with vinyl ester resin along with a corrosion barrier of chopped strand E glass or chopped ECR glass mat.
“Because of the scrubber efficiency requirements, especially in the spray towers, the spray zones have shrunk, creating an impingement situation where the limestone slurry is shooting onto the spray header below it,” he explains. The higher volumes of abrasive slurry showering down on the piping in these designs can reduce the FRP material’s service life. “We actually did a generation change on our abrasion resistant piping to address it. That’s the biggest change we’ve been affected by in recent years.”