Experimental study of air-water up-flow in a packed column using laser Doppler anemometry

The hydrodynamics of an air-water flow in a column has been analyzed. The reactor consisted of a vertical column of 0.055 m diameter and 0.255 m height, made of acrylic to achieve good visualization of the bubbles. The column was partially packed with solid cylindrical pellets. The study was focused on the region above the packed zone in three vertical positions. Measurements of velocity in ascendant flow direction were conducted at each position using laser Doppler anemometry. Velocities along the column diameter were experimentally determined for two liquids flow, 300 and 600 L/h. Two conditions of Reynolds number were obtained, Re: 8.3 and 16.7 x 10(3) based on inlet pipe diameter and water properties. The results show that the size and shape of the bubbles become smaller and uniform when the column was packed. Experimental measurements of the velocity were difficult to determine when the Re was higher ( Re > 17 x 10(3)). Also, the velocity profile showed instability of the flow, mainly in the near packed region. However, an average value of the velocity could be observed as function of the inlet condition.