Efficient Design of Industrial Fan and Combustion Silencers by Finite Element Tools and In-Duct Source Characterisation

Abstract

This paper presents three case studies of designing and manufacturing a silencer for an existing exhaust duct or project. In all three cases, acoustic finite element method (FEM) was utilized successfully as the main acoustic design tool. First case is an exhaust air duct silencer for a thermal insulation factory. The noise from exhaust air channel of water treatment plant fans presented strong noise emission at two blade pass frequencies, causing disturbance in the nearby neighborhood. Reactive channel silencer was designed to attenuate the noise at the problematic frequencies. Second case concerns design of a simpler but more effective silencer for emergency diesel generator (EDG). Third case is an exhaust gas duct silencer for a gas turbine power plant. Distinctive features of the case were very large silencer dimensions and needed tolerance for exceptionally high exhaust gas temperature. The three presented case studies had their own unique features and challenges, and design basis for each case were different from each other. Acoustic design addressing the challenges was successful in all three cases. In one of the cases the solution is already implemented at the plant, with a result satisfying the customer and fulfilling all design targets.