Axially resolved measurement of axial gas dispersion in bubble columns via gas flow modulation technique

• Gas flow modulation allows axially resolved gas dispersion measurements. • The axial gas dispersion coefficient varies along the column axial direction. • Sparger performance strongly affects dispersion phenomena at low gas velocities. • Non-uniform gas distribution causes enhanced dispersion in the sparger region. The Gas Flow Modulation technique (GFM) is a recently introduced approach for measuring axial gas dispersion coefficients in bubble columns. This technique overcomes the limitations of the traditional tracer-based approaches, enabling axially resolved measurements. The present work evaluates the effects of column diameter, gas sparger design and gas superficial velocity on the axial gas dispersion coefficient. Applying GFM, this parameter is evaluated compartment-wise along the axial position in the column. The results highlight a strong influence of the gas sparger design and formed gas bubbles on the dispersion phenomena. In addition, the axial gas dispersion coefficient was found to change significantly along the column axial direction. This study highlights the potential role of GFM for developing reliable dispersion correlations and advanced reactor models in the future