Removal of oil from electric desalting wastewater using centrifugal contactors

To solve the problem of over-standard oil content in electric desalting wastewater (EDW), a new process for removing oil was designed based on centrifugal contactors. In addition, an industrial sidetrack tester was established. The effects of rotor speed, inlet flow rate, water temperature, oil content, and crude oil density on separating performance were studied. Results show that oil removal efficiency increases with the decreasing inlet flow rate, increasing oil concentration, or decreasing oil density. At 50-90 °C, oil removal efficiency remains stable but initially rises first and then falls with increasing rotor speed, whereas the water content in separated waste oil (SWO) initially decreases and then increases. Oil concentrations ranging from 4000 mg/L to 60,000 mg/L can be reduced to below 200 mg/L using centrifugal contactors. The proposed process is highly efficient for separating oil from EDW.