Eliminating air-flow-induced acoustic vibration in coal pulverizers

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. (C) 1998 Academic Press.