Fluidized Bed: Online Monitoring of the Particle Temperature

In a fluidized bed, the online temperature of the particles is important for monitoring the process and for monitoring the process and understanding the heat transfer mechanisms. In order to minimize the influence of the air on the particle temperature measurement, thermal cameras were recently used to determine the particle temperature non-invasively. When using a thermal camera to monitor the particles in a fluidized bed, especially in an ordinary fluidized bed, it is expected that some the particles in the thermal images will be blurry. The blurry particles can be caused by the particle movement and the thermal camera focus. In order to measure the particle temperature accurately, the clear particles and the blurry particles in the thermal images should be considered separately. In this thesis, based on the calibrated particle size and shape, only the pixels that represent the clear particles in the thermal images were identified and correlated to the particle temperature. Using this technique, the online temperature of the particles was measured together with the temperatures of the air and the fluidized bed wall. It was found that higher inlet air velocity and higher loaded particle mass can accelerate the heating process of the particles more than the heating process of the fluidized bed wall. At the temperature steady state, a two-compartment model was developed to correlate the heat transfer coefficients between the air and the particles and between the particles and the fluidized bed wall. It was found that the relationship between them depends on how the void fraction and the particle Reynolds number are related to the contact area between the particle and the zones (hot and cold) and the time that the particle spent in the zones.