Refinery Desalter Effluent Treatment Process
Refinery desalter effluent is a difficult oily wastewater generated during crude oil processing, characterised by high oil content, severe emulsification and large water-quality fluctuations, so conventional treatment methods struggle to meet standards consistently. As environmental requirements tighten, an efficient, economical and stable treatment process has become an urgent industry need.
Process Core and Technical Features
Modern refinery desalter effluent treatment mainly uses purely physical separation technology, represented by the combined process of 'coalescing oil separator + CDFU (cyclonic dissolved gas flotation)'. Through multi-stage synergy the process achieves efficient oil-water separation: the coalescing oil separator first breaks most of the emulsified oil, and the CDFU then captures residual oil droplets efficiently with micro/nano bubbles, ultimately achieving effluent oil content of 150 mg/L or less and suspended solids of 150 mg/L or less.
Process flow diagram. For specific scheme design or parameter optimisation, water quality data can be provided to further customise the solution.
The technology offers notable advantages: purely physical separation with no chemicals, and recovered oil is of good quality and can be returned directly to refining; no oily sludge (hazardous waste) is generated, eliminating secondary pollution; the process flow is short and the equipment compact, with a footprint only 1/3 of conventional processes; and the skid-mounted design supports rapid deployment and online implementation.
Practical Application Results
The process has been successfully verified in several large refining and chemical projects. The PetroChina Urumqi Petrochemical 100 m³/h treatment project adopts two-stage CDFU process, with inlet oil content of 30,000 ppm or less and effluent stably controlled at 150 ppm or less.
Operation of the Sinopec Cangzhou Branch 50 m³/h unit shows oil removal efficiency above 95%, with water content of recovered waste oil of only 0.5%-10%.
The Sichuan Petrochemical 70 m³/h project achieved even better results, with effluent oil of 100 mg/L or less (around 50 ppm on average), maintaining stable operation even when the influent oil shock reached 40%.
Technical Development and Outlook
With continuous innovation in core technologies such as ultra-fine nano bubbles, material surface modification and high-gravity mass transfer, desalter effluent treatment is moving toward higher efficiency and greater intelligence. Intelligent control systems enable unattended operation, and special materials extend equipment life to more than five years.
The process successfully solves the problem of desalter effluent shocking downstream wastewater treatment plants; while achieving environmental compliance, it also creates significant economic benefits through oil recovery, becoming important technical support for the green transition of refineries. With further process optimisation and new materials, treatment precision and efficiency will improve further, providing strong support for the sustainable development of the refining and chemical industry.
