Numerical Simulation on the Structure Selection of Oil-Water Pre-separation Zone in a Compact Flotation Unit

The oil-water separation performance of 4 kinds of pre-separation zone structure of a compact flotation unit (CFU) was studied with computational fluid software Fluent. Based on the steady and reliable computational model, the de-oiling efficiency and oil-phase distribution of the 4 structural configurations were studied under the design flow rate and inlet oil content firstly, and the effects of flow rate and inlet oil content on the de-oiling efficiency of a CFU were examined. The numerical results show that for the same kind of pre-separation zone structural configuration, the de-oiling efficiency is relevant with the flow rate and inlet oil content, which increases with increasing of inlet oil content when the flow rate is given, and decreases with increasing of the flow rate when the inlet oil content is given. The comprehensive oil-water separation performance of cylinder with bell-mouth upward structure is the best under the conditions of designed flow rate of 4 m 3 /h and inlet oil content of 2 000 mg/L, the oil-water separation efficiency is 87.13%, and this structure configuration has wide operating range.