CONCLUSIONS

In order to intensify the mass transfer for gas-liquid-solid reaction in fixed bed, CMGD was applied to disperse gas into a large quantity of multi-scale bubbles in liquid phase, increasing the gas-liquid interfacial area to improve the mass transfer efficiency. The effects of gas-liquid flow rate and rising height on bubble size were investigated. The results show that the d av is ranging from 330 to 345 μm and the quantity of bubbles is 500 under the optimal conditions of 10 cm ceramic membrane, gas flow rate of 10 ml/min, liquid flow rate of 1 ml/min. A large number of bubbles will coalesce in ceramic membrane channel and rising process, which is contrary to the strategy of increasing the two-phase boundary area. The ceramic membrane channel was divided into several channels by installing baffle-type internals, consequently reducing the radial migration between bubbles and significantly inhibiting the coalescence of bubbles. This work revealed the influence of operating conditions and internals on bubble size in CMGD, and discussed the deformation, coalescence, trajectory and velocity of multi scale bubbles, contributing to gas-liquid dispersion, enhancement of mass transfer efficiency and improvement of heterogeneous catalytic reaction performance.