Dynamic Bubble Tracking in Fluidized Beds Via Electrical Capacitance Volume Tomography

Detailed knowledge of the dimensions and velocities of bubbles in fluidized beds is invaluable for the development and validation of correlations and models of particles in fluidized bed systems. This work sets forth the development of a novel, dynamic bubble detection algorithm for use with electrical capacitance volume tomography (ECVT) sensors for bubbling fluidized beds. The novel phase detection method was developed to address the shortcomings of other published methods by more fully utilizing the three-dimensional capability of the sensors. After the sensor parameters were optimized to verify capability of bubble detection, measurements were made with glass beads as well as quartz sand. A range of air velocities in a 10 cm diameter bubbling fluidized bed were used. The results largely agree with the fundamentals of bubbling fluidization and results from publications with similar experimental setups. Within each measurement the bubble dimensions, velocities and frequencies over the axial and radial position could be evaluated. Due to the three-dimensional nature of the novel bubble detection technique, insight into the directional tendencies of detected bubbles was gained. For example, bubble migration toward the radial center of the bed, as well as radial and axial bubble coalescence and splitting, are more clearly evident from the trends that are producible with this method.