Coalescence, breakup and liquid circulation in bubble column reactors

摘要

Bubble columns are widely used for carrying out reactions and mass transfer operations in chemical, pharmaceutical and biochemical processes. This thesis concerns the modeling of the characteristics for bubble column reactors in order to provide the basis for solving the engineering problems such as design, scale-up and process control of the reactors. The background of this study is to improve the utilization of natural gas resources. A new model to be used with the dynamic gas disengagement technique has been developed, based on the concept of non-uniform steady state gas holdup and bubble size distribution. The model is shown to predict the distribution of bubble classes, and thereby gas holdup, in agreement with experimental data. The model shows that the classification of bubbles according to their rise velocities, which is the basis of the DGD technique, is reasonable and effective. The five-point conductivity technique is verified by measured results. The bubble size distribution and the specific interfacial area have been deduced based on the assumption of a constant rise velocity for a given bubble class through the whole disengagement process. Integrating this as the swarm terminal velocity, Sauter mean diameters and specific interfacial areas could be determined in fair and good agreement respectively with those found experimentally over a wide range of gas velocities (2-18 cm/s). 130 refs., 67 figs., 5 tabs.