Compared with the commonly used gas-liquid bubble tower, the tubular gas-liquid contactor has the advantages of high gas content rate, low energy consumption and simple maintenance to strengthen the gas-liquid mass transfer process by generating a uniform bubble-like and highly dispersed system in the pipeline space.A micro-bubble type tubular gas-liquid contactor was developed independently which utilizes the high-speed shear crushing effect of a venturi jet bubble generator to generate micro bubbles.Based on computational fluid dynamics (CFD) numerical simulation and indoor experiments,the bubble formation mechanism and bubble size distribution of the micro bubble tubular gas-liquid contactor were investigated.The results show that the VOF multiphase flow model coupled with RNG k-ε turbulence model can simulate the jet impingement process and bubble formation characteristics. In the expansion section of the venturi jet bubble generator,large bubbles are sheared and broken into micro bubbles, and the bubbles are uniform and stable. The particle size of bubbles decreases with the increase of liquid volume, and the particle size of bubbles is the smallest (76.5 μm) when the liquid volume is 14.0 L/min, the gas volume is the maximum natural suction volume, and the length of the column is 800 mm. The bubble particle size increases with the increase of gas volume, and is the smallest (86.7 μm) when the gas volume is 1.5 L/min, the liquid volume is 8.0 L/min, and the length of the column is 800 mm.As the length of column increases, the bubble size first decreases and then remains basically unchanged. When the column length is greater than 800 mm, its impact on the bubble particle size is relatively small.

The flow field datributions of the hydrocyclone such as static pressure, tangential velocity and turbulent dissipation rate by loading PBM model and the conventional model, respectively. The results show that the two methods are approximately the same in the prediction of flow field characterics. Therefore, the CFD numerical simulation method based on the PBM model was used to simulate the separation characteristics of the hydrocyclone numerically. And the effects of the factors such as inlet flow rate, overflow split ratio, oil phase viscosity and density on the oil droplet size distribution and oil?water separation characteristics are explored. The results indicate that the separation efficiency of hydrocyclone increases firstly and then decreases with the rising of the inlet flow rate, and reaches a maximum efficiency of 98% as the processing capacity is 4 m³/h; the increase of the overflow split ratio is beneficial to improve separation efficiency; the radial force on the oil droplets decreases with the increasing of the viscosity of the oil phase, preventing aggregation and significantly reducing the separation efficiency as well; the higher density of the oil phase leads to larger the average oil droplet diameter of the tail pipe section and a reduced separation efficiency. Above all, the CFD?PBM numerical simulation method can be used to investigate the particle size distribution and variation characteristics of oil droplets in hydrocyclone, in order to reveal the separation mechanism of the hydrocyclone from different scales.