Filtering even a percentage of the total flow can yield significant return on investment (ROI). A power-generating company installed filtration to handle 2 percent of its 150,000 gal/min flow. Its engineering staff determined that it would save $818,000 per year, including:
- $30,000 savings in tower basin and condenser tube cleaning
- $170,000 in cooling water chemical treatment costs.
- $306,000 in improved condenser efficiency.
- $312,000 in high-efficiency fill costs.
"We figured our ROI would be under 18 months, and it turned out to be around 15 months," he says. "That's a good ROI. We ended up buying two more here and two bigger ones for the towers across the street."
Other customers have noted similar savings. A Midwestern steel mill installed an automatic self-cleaning screen filter and saw manual basket screen cleaning –- which had to be performed as frequently as every three hours during stormy weather –- drop to zero. An aluminum casting operation extended the interval on its manual chilling mold clean-outs to 20 days, a vast improvement over the three-day cycle its operations crew had maintained before they installed a self-cleaning screen system.
"Whatever you're doing, you have to be filtering out more material than the ambient air is introducing," says Tom Hamilton of Power Products in Vancouver, Wash. "We've found 10 percent to be very effective. You're eventually going to get to a stable state."