Abstract: Aiming at the characteristics of high oil content and low sludge content in Xingzhong oil sludge, a new double-layer cyclone structure is proposed for the three-phase separation of oil-water-particles. Numerical simulation is used to study the separation effect of single-layer cyclone and three double-layer cyclones with different inlet type by selecting the hybrid model and k-e model, and analyze the effects of each cyclone structure on the pressure distribution, oil-water distribution and sludge particle distribution efficiency. The results show that: the cyclone separation effect is the best when the inlet flow rate is 40 m³/h, i.e., the inlet flow rate is 6 m/s; the pressure in the outer layer of the double-layer cyclone conforms to the pressure distribution characteristics of the cyclonic field, and the pressure difference distribution in the inner layer is not obvious, but the pressure is stable, which can further separate the fluid and oil sludge particles; the oil phase purity in the inner layer of the three types of double-layer cyclones is above 95%; and the oil phase purity in the overflow of the inner cyclone is more than 99%. The structure of double-layer cyclone can improve the three-phase separation effect of oil-water-particles effectively.

Key words: hydrocyclone, numerical simulation, sludge particles, separation efficiency