SINOKLE Solves the Sulfur-Containing Wastewater Challenge with an Innovative Cyclonic Dissolved Air Flotation plus Coalescing Oil Removal Process
In the petroleum refining industry, the sulfur-containing wastewater produced by delayed coking units is extremely difficult to treat because it contains high concentrations of emulsified oil and fine coke powder, and it has long troubled the stable operation of production units and environmental compliance. Conventional single treatment technologies often address one problem at the expense of another, with limited effectiveness. Recently, SINOKLE announced that its independently developed combined process of cyclonic dissolved air flotation (CDFU) plus coalescing oil removal has been successfully applied at industrial scale in a large refinery of Sinopec, achieving breakthrough results and providing an efficient, economical and reliable innovative solution to this industry pain point.
Facing the Challenge Head-On: Sulfur-Containing Wastewater Is a Persistent Problem for the Industry
Delayed coking is a key process for treating inferior heavy oil, but the sulfur-containing wastewater it produces has a complex composition, containing large amounts of stable emulsified oil formed by natural surfactants and additives, as well as fine coke powder. If these pollutants enter the downstream stripping unit directly without effective pre-treatment, they easily cause tray coking and blockage, foaming and disruption of the gas-liquid balance. This not only greatly increases steam consumption and equipment maintenance costs, but may also cause unplanned shutdowns, seriously affecting the smooth operation and economic performance of the entire refining chain. Conventional settling, filtration or chemical demulsification methods suffer from a large footprint, unstable treatment performance, high operating costs or easy clogging.
Innovative Solution: Multi-Technology Coupling Achieves Advanced Purification
SINOKLE precisely targeted the industry pain point and innovatively coupled cyclonic dissolved air flotation (CDFU) with coalescing oil removal technology deeply, supplemented by coarse and fine two-stage filtration, forming a complete pre-treatment process package.
Core Technology One: Cyclonic Dissolved Air Flotation (CDFU). This technology generates large numbers of micro- and nano-scale bubbles through a dissolved air pump. Under the powerful centrifugal force generated by the cyclonic field, the bubbles collide efficiently with and adhere to emulsified oil droplets and suspended coke powder in the wastewater. The cyclonic action not only greatly increases the contact frequency and capture probability between bubbles and pollutants, but the turbulent vortices it produces also effectively break down the stable system of emulsified oil droplets, achieving efficient demulsification and initial separation.
Core Technology Two: High-Efficiency Coalescing Oil Removal. The wastewater treated byCDFUthen flows through an oil remover fitted with specially modified coalescing packing. This packing has excellent hydrophobic and oleophilic characteristics and can capture the remaining fine dispersed oil droplets in the water like a magnet, causing them to coalesce and merge into large droplets that rapidly float and separate under buoyancy, achieving advanced removal of the oil phase.
Supporting Safeguard: Precision Filtration for Coke Removal. Auto-backwashing coarse and fine filters are installed at the front of the process, effectively intercepting and removing coke powder and solid impurities from the wastewater, ensuring long-term stable operation of the downstream core equipment and preventing clogging.
The entire system adopts a modular skid-mounted design with a small footprint, particularly suitable for technical upgrades of existing refineries, achieving a unity of intensification and high performance.
Industrial Verification: Outstanding Performance Withstands Production Conditions
This technology was fully verified in the sulfur-containing wastewater treatment of a 1.4 Mt/a delayed coking unit at a Sinopec refinery. The industrial operating data is striking: during normal production stages (non-steam blowdown), the average oil concentration in the wastewater before treatment was as high as 45,000 mg/L, and after treatment by this combined process the average effluent oil concentration dropped to 175.11 mg/L, with an average oil removal rate of 98.83%; suspended solids (coke powder) dropped from an average of 353 mg/L to 7 mg/L, with clear and bright effluent.
In the more demanding steam blowdown stage (when wastewater flow is high and oil and coke powder concentrations rise sharply), facing a shock load with an average oil concentration as high as 197,000 mg/L, the technology demonstrated strong fluctuation resistance, with average effluent oil concentration still controlled at 285 mg/L and average oil removal rate further rising to 99.85%, while suspended solids removal performance remained stable and excellent.
Significant Benefits: A Double Harvest of Environmental and Economic Performance
The successful application of this technology has brought multiple benefits: it safeguards safe, stable and long-term operation of the unit by eliminating coke powder and emulsified oil damage to the downstream stripping column at the source, significantly reducing unplanned shutdowns and maintenance frequency.
It creates direct economic benefits: the system operates with low energy consumption and requires no large amounts of chemical agents. At the same time, more than 560 tonnes of high-quality light oil can be recovered each year, which alone generates nearly 4 million yuan in economic returns, with a high return on investment.
It improves environmental protection and resource utilisation: it greatly reduces the load on downstream wastewater treatment plants and creates good conditions for advanced wastewater reuse (such as injection water for electric desalting), embodying the concepts of energy saving, emission reduction and resource recycling.
The successful industrial application of SINOKLE's cyclonic dissolved air flotation plus coalescing oil removal technology is not only a major technical breakthrough in the field of sulfur-containing wastewater treatment for delayed coking, but also provides a completely new solution and successful example for the pre-treatment of difficult emulsified oily wastewater across the refining and chemical industry. It marks China's leading independent research and development and engineering capability in the field of special separation technology for industrial wastewater.
