Dead-man temperature distribution measurement in a blast furnace by acoustic CT method

A new sensor measuring two dimensional temperature distribution of the dead-man in a blast furnace has developed by using an acoustic wave CT method based on the theory that acoustic velocity in gas depends on a temperature. The features of a new measurement apparatus transmitting and receiving the acoustic wave which decreased to a great extent in packed bed is as follows. Shock wave is used in transmitter to generate acoustic wave with large acoustic pressure. Receiver has the good sensitivity for low frequency. Then, the least square method is adopted for computed tomography since the number of acoustic velocity data is limited. Relationship between temperature and acoustic velocity in a packed bed was obtained in off-line experiment. The measurement in an actual blast furnace was carried out during the scheduled shutdown. The acoustic wave was transmitted from a tuyere and the wave propagated through the furnace were received at some tuyeres. The temperature calculated by this method showed the decreasing tendency from side wall to the center of the blast furnace. An isothermal line of the temperature distribution had the possibility to show the shape of the dead-man. The temperature measured by this method was about 100 °C lower than that measured by thermocouple.