AirStream conducted fan performance assessments in January of 2013, which indicated that fan efficiency was only 54.2 percent for a two fan flow of 488,025m3/hr. We proposed fan upgrades that guaranteed an increase in efficiency to 87 percent. The two fan drive-input power use would be lower by 287 kW at test flow. Additionally, the new rotors would attain much more pressure and a flow of 666,000m3/hr with future 1250-hp motors. For present operation up to 596,000m3/hr, the existing 800-hp motors would be used.
The upgrade consisted of two new backward curved-blade rotors and was engineered to minimize equipment and installation costs by reusing the existing fan housings, dampers, couplings, and bearings. Although the rotors were 26 percent larger than the existing rotors, only modest fan housing modifications were needed.