Bubble measurement in three‐phase fluidized beds using a u‐shaped optical fiber

A photometric technique is being developed to study bubble behaviour in three‐phase fluidized beds constituted by fine particles. A custom made U‐shaped single core silica fiber (400 μm diameter) is used as the bubble sensor. A helium‐neon laser beam is introduced at one end of the U probe and the variation of the light intensity, occurring when a gas bubble contacts the sensor, is detected at the other end of the fiber. The velocity and axial length (cord) of the bubbles were measured by four such probes in a two dimensional bed. This technique could be applied to study the bubble behaviour and to provide experimental data for estimating the performance of reactors with severe operating conditions of high temperature and pressure.