Multiphase flows have a large applicability in the industry and its studies are very important. One example of three-phase system is bubble columns operating with solid phase as catalyst in the process. In this context the hydrocracking systems are used to process heavy oil and are becoming very common at oil refineries. Its operation is done in multiple-stage each one in a different reactor. In this work, it is proposed a new geometry of bubble columns in which two different solid phases are considered inside the system. The technique used in this work is Particle Image Velocimetry (PIV) in which it is possible to measure velocity fields inside the columns without interfering with the flow. Rhodamine B is a tracer for the liquid phase and the PIV is extended to the Fluorescent Stereo-PIV using two CCDs cameras that allow estimating the third component velocity. In this work it is analyzed the fluid dynamic of the liquid phase inside a three-phase bubble column with expansion of diameter when compared with a traditional bubble column with cylindrical geometry. The liquid phase is water at 22 degrees C, FCC catalyst with diameter of 100-125 mu m and air as gas phase injected at the bottom with constant flow set at 1.5 L/min. Besides, the two column geometries present different positions and the experimental results show the input of different solid concentration inside the system to analyze the influence over the liquid phase average velocity field. The comparison of two columns with different solid concentration is presented and discussed.43 16511656