The noise from a pair of new cooling towers had ignited complaints from residents across the road from the site. A typical acoustic consultant was drafted-in who recommended the industry default silencers and a noise barrier without carrying out any diagnosis. Not good practice, let alone best practice.
The predicted effect on the plant noise of fitting the typical conventional acoustic package of silencers and a barrier along the edge of the site was to reduce the noise level down to around 56dB(A) at the neighbours - still far too high for the area. Despite a total cooling tower noise attenuation package costing well over £40k, not only would the problem not have been solved but in addition, as the acoustic barrier would have caused serious transport access problems, the company had to look for alternatives.
Our solution was based on a very accurate diagnosis and ranking of the cooling tower fan, drive and pump noise sources to develop an engineering source control package. The final noise reduction measures for both cooling towers comprised:-
This package achieved a noise level of <50dB(A) at a cost of only £6k and without affecting normal site operation or cooling tower efficiency. Around 15% of the cost and more than 4 times the attenuation of the conventional noise reduction measures.