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Noise-emission characteristics of circular mechanical, natural, and fan-assist natural-draft cooling towers with silencers

Conference · · Proc. Am. Power Conf.; (United States)
OSTI ID:6661189

Inlet noise, mainly water noise, of all large, wet towers tends to average 85 to 86 dBA. Propagation of this noise, with respect to distance, is similar for all sizes of wet-style cooling towers. Outlet noise emission characteristics of circular mechanical-draft, fan-assist, and natural-draft towers show inlet-to-outlet chimney attenuation on the order of 1.5, 3.5, and 15 dB, respectively. There is a potential for outlet noise to be perceived at 3280 to 4920 ft. Berms provide effective reduction of near-field inlet noise (15 dB) for natural-draft towers, while application of mineral wool absorptive silencers to natural-draft or fan-assist inlets can provide noise attenuation of 10 to 40 dB. Silencers can be selected to control specific emission level from tower outlets as well. Lowering of fan speed for circular mechanical-draft or reducing numbers of fans on line for fan-assist towers produces noise buildup on the order of 2 dB rather than noise reduction at the inlet and outlet. When the cost is justifiable, noise reductions as much as 40 dB can readily be achieved.

Research Organization:
Stone and Webster Engineering Corp., Boston
OSTI ID:
6661189
Report Number(s):
CONF-770403-
Journal Information:
Proc. Am. Power Conf.; (United States), Journal Name: Proc. Am. Power Conf.; (United States) Vol. 39; ISSN PAPWA
Country of Publication:
United States
Language:
English