Oil-water separation in a cylindrical cyclone with vortex finder

Abstract

Cylindrical cyclones are always used in the petroleum industry to separate the oil-water two-phase mixtures or treatment the waste water. Here, we use dimensional analysis and multiphase flow numerical simulation to analyze the separation process in a cylindrical cyclone with a vortex finder to better understand the theory and characteristics of separation. In the dimensional analysis, we consider all structural, flow, and operating parameters. A multiphase mixture model is used to simulate oil-water two-phase flow and separation in a cylindrical cyclone. There is a vortex in the core of the cylinder, and its structure is influenced by the diameter of the overflow pipe, the inlet velocity, and the flow split ratio. However, the influence of these three factors on the equivalent diameter of the vortex core can be ignored. Moreover, the inlet velocity has little influence on the equivalent length of the vortex core. Therefore, the structure of the vortex core can be calculated from the diameter and flow split ratio of the up-outlet of the cylindrical cyclone. Oil-water separation increases as the diameter of the oil droplet increases. The separation efficiency of the cylindrical cyclone with vortex can reach 80% if the inlet dispersion droplet diameter is larger than 1 mm. The oil volume fractions in the up- and down-outlets decrease as the overflow split ratio increases. The flow split ratio is the only operating parameter to consider to obtain the best separation results for a cylindrical cyclone with a fixed inlet oil-water mixture.