| 摘要 |
PROBLEM TO BE SOLVED: To provide a nose reduction device connectable to a burner of an existing asphalt plant narrow in the installation part periphery, without stopping operation of the asphalt plant, by effectively utilizing the existing burner.SOLUTION: A noise reduction device of using an L-shaped duct of the present invention is a device connected to a burner 1 of an asphalt plant and reducing noise generated by the burner 1, and comprises: a cylindrical duct 3 formed in an L shape stuck with a sound absorption material on an inner wall thereof, the cylindrical duct 3 having one end of becoming a connection part to the burner 1 and the another end of becoming an opening end part; a detection microphone 4 for detecting noise in the duct 3; a controller 7 for converting a sound wave of the noise in the duct detected by the detection microphone 4 into the antiphase; a loudspeaker 5 for generating the sound wave of the antiphase by output from the controller 7; and an error microphone 6 for detecting the noise after generating the sound wave of the antiphase by the loudspeaker. The detection microphone 4 is provided in a position for detecting the noise, of a straight line part on the connection part side to the burner 1, of the duct, and the loudspeaker 5 is provided so as to issue a sound in a straight line part on the opening end part side of the duct. |
