Abstract: An apparatus for neutralizing acidic or acid-containing pollutants in furnace flue gases comprising a flue gas duct having an inner pipe suspended therein and arranged so that the flue gases can flow both inside and outside the pipe. Preferably, the gases flow upwards around the outside of the pipe to an outlet zone. Atomizers project into the inner pipe for spraying an extremely fine suspension of a neutralizing agent in water into the flue gases flowing through the pipe. The inner pipe is formed from a plurality of longitudinal strips which are separate from each other and are suspended from their upper ends. Vibrating apparatus is provided for periodically vibrating the strips to dislodge deposits of neutralizing agent and fly ash on the inside of the pipe, thereby preventing the build-up of a permanent coating.