Yongli Ma

A fractal tree-structured gas–liquid–solid microfluidized bed was developed to overcome the limited throughput of single-tube microfluidized beds and the hydrodynamic changes caused by direct scale-up. The minimum liquid fluidization velocity, cross-level particle migration, and bubble dynamics at different hierarchical levels were systematically investigated. The results show that the minimum liquid fluidization velocity can be identified by combining the empty-bed-corrected pressure drop-liquid velocity curve with the Hurst exponent. With gas introduction, both the minimum liquid fluidization velocity and the critical liquid velocity for particle migration decrease as the superficial gas velocity increases. The mean bubble diameter decreases with increasing liquid velocity but increases with increasing gas velocity and particle diameter. These results indicate that the fractal tree structure provides a potential pathway for hierarchical scale-up of gas–liquid–solid microfluidized beds.

The polymerization of isobutylene is an important chemical reaction process. In order to overcome the shortcomings of existing industrial fixed‐bed reactors in application, a new gas‐liquid‐solid circulating mini‐fluidized bed reactor with an inner diameter of 10 mm is developed. The influences of operating conditions, solvents, and reactant properties on isobutylene conversion, selectivity, and yield of di‐isobutylene were investigated. Compared with fixed‐bed reactor, the performance of the reactor was evaluated. The experimental results showed that the highest yield of di‐isobutylene was 83.4%. Under the same operating conditions, the conversion rate of isobutylene in the circulating mini‐fluidized bed is twice that of the fixed‐bed reactor. The reaction time to achieve the same conversion rate is reduced by 2.5 times. The solid particles and bubbles in the circulating mini‐fluidized bed not only provide a higher specific surface area but also cause hydrodynamic changes and effectively improve the reactor performance.