Numerical simulation study on the structure optimization of cyclone tube of horizontal compact cyclone air flotation device

Abstract

Due to the increase of the water content in the produced fluid from oilfield development and the limitation of space on offshore platforms, compact wastewater treatment equipment is urgently needed to treat oily wastewater. In this regard, a horizontal compact cyclone air flotation device was designed, and the flow field distribution and oil-water separation performance of the cyclone cylinder area of the device were systematically studied by the Fluent numerical simulation method. The effects of cyclone cylinder structure, inlet pipe diameter, oily sewage inlet velocity and inlet oil content on oil-water separation were explored. The results showed that when the inlet pipe diameter was 20 mm and the oily sewage inlet velocity was 2 m/s, the swirl tube structure using the guide vane could obtain a better flow field distribution. The larger the oily sewage inlet velocity, the more serious the attenuation of tangential velocity. When the height of the swirl cylinder was 100-300 mm, the tangential velocity attenuation was larger, and the attenuation was small within the height of 300-650 mm. Under the same oily sewage inlet velocity, increasing the inlet pipe diameter could increase the volume fraction of the oil phase in the cyclone tube. Increasing the oily sewage inlet velocity would lead to a decrease in the volume fraction of the oil phase. The volume fraction of oil phase in the cyclone tube was distributed in a “U” shape, and increased with the increase of inlet oil content, which was directly proportional to the inlet oil content.

Keywords

• compact flotation unit
• air floatation swirl
• structural optimization
• numerical simulation