Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Bubble column reactors are widely employed for gas-liquid reactions due to their superior mass and heat transfer accompanied by being geometrically simple and free from any moving part. However, the gas sparger is a crucial device, which directly determines the process performance. The bubbles released from the orifices of the gas sparger start rising up and buoyancy and drag forces etc., in turn, depending on bubble size, control the traveling velocity of the bubbles, and eventually the overall hydrodynamic behavior, such as mixing and gas holdup. Hence, to get an insight into the impact of orifice patterns and holes’ diameter of a gas sparger on the axially evolving gas-liquid dispersion, an ultrafast X-ray tomography study is performed in a 2 m height bubble column of 100 mm diameter. Two different perforated plate-type spargers are used, namely a single orifice sparger with a 2.9 mm center hole and a plate with 13 orifices arranged in a triangular pitch with a hole diameter of 0.8 mm, respectively. The experiments were performed in a non-coalescing system for superficial gas velocities up to 2.5 cm/s. From the X-ray measurements, the evolving gas structures, the bubble size distributions as well as the cross-sectional gas holdup distributions are extracted along the column height and the benefit of a fine initial distribution is evaluated.