The bubble size, gas holdup, and interfacial area in a swirling contactor were investigated through experiments and simulations. The interfacial area was obtained for liquids and gases with Reynolds numbers Rel and Reg, respectively. The contactor was divided into 12 subregions. When Reg=23.8 and Rel =20075.4, regions near the side wall and center of the swirl contactor exhibited small bubbles with diameters of 0.33–0.40 and 0.38–0.45 mm, respectively. Rel was negatively related to bubble size, gas holdup, and interfacial area, whereas Reg was positively related. The maximum bubble interfacial area among the 12 subregions was 530 m-1,and for the entire swirling contactor was 196.3 m-1 with a gas–liquid ratio of 0.022. Euler-Euler simulations using the population balance model accurately predicted this area. Larger areas were obtained at lower Rel values. Increasing the liquid velocity is not necessary to achieve larger areas, which indicates a contactor with lower energy consumption.

The movement of fine bubbles in a swirling field determines the mass transfer, heat transfer, and reaction performance of the swirl equipment. This study investigated the separation of fine bubbles strengthened by a swirling field in order to achieve higher separation efficiency of the planar cyclone through optimizing the structure of the convection field. The bubble size and gas holdup in the swirling flow field under different working conditions were explored by combining high-speed camera online measurement and computational fluid dynamics(CFD) simulation. The gas holdup and bubble size of each region in the swirl region, as well as the separation efficiency of gas by swirl eccentricity, were observed at different liquid and gas Reynolds numbers, Rel and Reg, respectively. Furthermore, the influence of different swirl eccentricities, dc, was investigated. It found that the highest separation efficiency can be achieved under all working conditions when swirl eccentricity dc= 5 mm.

The hydrodynamics of gas and liquid flow through a granular bed were proposed in this work. A high-speed camera was used to capture bubbles at different heights in a granular bed. The effect of bubble size on the rising velocity and stagnation of single bubble and multiple bubbles was investigated. The results showed that a single bubble rose along a non-uniform trajectory. The average rising velocity increased nonlinearly with the increase of the initial bubble diameter. This work also provides a visual verification that multiple bubbles stagnation occurs. The results show that the rising velocity and bubble size were the two key factors, which dominate the stagnation probability. The rising velocity of multiple bubbles is expressed by the overall velocity, and the bubble size is expressed by the projected area, which is found the bubble projection area and the overall velocity of the bubbles were negatively correlated with the stagnation.

A gas-liquid stirred tank reactor (STR) has some problems, such as low mass transfer efficiency, high exhaust gas oxygen concentration, and low product conversion rate, due to limitations of stirring speed and input power. This article proposes a method to enhance the gas-liquid mass transfer in a STR using circulating jet internals. When a circulating jet is added, the average bubble size in the reactor is reduced to 1.26 mm, and the overall gas holdup is increased to 8.23%, which is an increase of 3.62 times of the original STR. The gas-liquid volumetric mass transfer coefficient is increased to 0.05556 s-1, which is 4.84 times of the original STR. The unit volume power is increased by only 1.4 times. These data provide references for the design and scale-up of new jet STRs.

An industrial-scale internal loop airlift reactor is used to remove volatile gas from high-viscosity molten sulfur. The effects of the superficial gas velocity and reactor height on the hydrodynamic characteristics were studied. The gas holdup, average bubble diameter, and liquid circulation velocity in the reactor under different conditions were analyzed using computational fluid dynamics simulation. The superficial gas velocity was varied from 0.0056 m/s to 0.05 m/s at a constant reactor height of 15 m. The total reactor height was varied from 5 m to 25 m at a superficial gas velocity of 0.0389 m/s.Based on the correlation between the gas holdup and liquid circulation velocity proposed by Chisti (1988), an optimized correlation between the gas holdup and liquid circulation velocity was developed by considering the influence of the bubble diameter. The results obtained using the proposed correlation were compared with those obtained using the Chisti correlation and simulation.

Based on the premise that large bubbles are removed in larger cyclones and small bubbles are removed in smaller cyclones, a combined degassing hydrocyclone with main and subsidiary chambers was designed to enhance liquid degassing. The liquid feed volume flow rate ranged from 0.377 to 1.459 m3/h, and the gas feed volume flow rate ranged from 0.197 to 1.000 m3/h. The pressure loss, liquid flow rate at the gas outlet, split ratio, gas flow rate at the liquid outlet and degassing efficiency of the degassing hydrocyclone were measured and calculated. Correlative equations for pressure loss and degassing efficiency were established. The experimental results show that the degassing hydrocyclone can remove most of the gas and has good degassing performance in a large gas-liquid flow rate range. The parameter contours provide an effective foundation for the removal of gas from industrial fluids.