A novel method is presented here for eliminating acoustic vibration within coal pulverizers. The method emerged from the study of an acoustic vibration which developed within the casing of a coal pulverizer at low to medium loads. The vibration was characterized by an acoustic quarterwave driven by swirling air flow of parallel high velocity air jets issuing from a rotating multi-air port arrangement. By converting the single frequency excitation energy of the air jets into turbulent energy utilizing a new air port design with strongly interacting (colliding) air jets, the vibration was eliminated. The theoretical background and results of the pre- and post-modification operational tests are presented.

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