Abstract
Recent advances in liquid-liquid centrifuge design coupled with experience gained in separating water from oil and oil from water provides a powerful, new option for petroleum production. The annular centrifugal contactor is a vertical, liquid-liquid, direct drive, low speed centrifuge that is capable of both mixing and separating in a single unit. Further design improvements which enhance this centrifuge's utility and efficiency in two-phase liquid separation are a low mixing sleeve and a clean-in-place rotor. Using the low mix mode, oil in water concentrations at the centrifuge outlet are typically in a range of 20 to 200 ppm, dependent upon the process conditions. Water in oil levels of less than 1% can be reached in heavier oil stocks and are even lower for light crudes and refined products. This new design is capable of processing input oil-water ratios which vary from 0–100% without adjustment. This important advancement is possible because, in this design, the oil-water interface can shift position within the separating zone of the rotor without causing a loss of separation quality. A clean-in-place (CIP) option consisting of numerous spray nozzles installed in the rotor's central hollow shaft is employed to deliver a cleaning solution to the inside diameter wall for rapid and efficient solids removal. The entire process can be automated to clean multiple centrifuges, sequentially, requiring only five minutes per unit. Examples of applications for this technology include; single stage oil dehydration, de-oiling process water, desalting of oil via washing, and other custom liquid-liquid processes.
