Process Breakdown: CDFU Cyclonic Flotation + Fine Filtration + KHC Coalescing Separation — A Full Analysis of the Three-Stage Refinery Sour Water Treatment Chain

In sour water treatment, oil removal is the key. This article breaks down SINOKLE's new process for refinery sour water treatment: what each of the three core units does, how they work together, and what results they deliver.

Start With the Water to Be Treated

Sulfides and nitrides in crude oil and its products are converted, during processes such as atmospheric and vacuum distillation, catalytic cracking, delayed coking and catalytic hydrogenation, through high-temperature pyrolysis, catalytic cracking and hydrocracking reactions, intoH2S and NH3-N. These enter the product streams, and once those streams are condensed and dehydrated or water-washed, sulfur- and ammonia-bearing wastewater is produced. Coking sour water is the hardest to treat: high coke powder content with a fine particle size distribution; high oil content with small droplets and severe emulsification; high sulfur, ammonia nitrogen and phenols; and a complex composition whose concentrations fluctuate widely.

Stage One:CDFUHigh-Efficiency Compact Cyclonic Flotation

Function: to separate free oil, dispersed oil and most of the emulsified oil. Principle: a cyclonic flow field is introduced on top of conventional flotation. After the oily wastewater enters the cyclone zone, the centrifugal force generated by high-speed rotation rapidly stratifies the oil and water phases, and the less dense oil droplets migrate toward the center. At the same time fine bubbles attach to the droplets, so that buoyancy and centrifugal force work together to carry the small droplets quickly to the surface. Compared with conventional horizontal-flow flotation,CDFUit offers higher efficiency, shorter residence time and a more compact footprint, making it especially suitable for refinery conditions where space is tight and influent quality fluctuates widely.

Stage Two: Fine Filtration

Function: to intercept fine suspended solids such as coke powder and protect the downstream coalescing separator. Principle: coke powder in sour water is fine-grained and easily penetrates conventional filter beds. Fine filtration uses higher-precision filter media to retain small particles and reduce turbidity, preventing particulate fouling and clogging of the coalescing media and ensuring stable long-term operation of the downstream stage.

Stage Three:KHC High-Efficiency Coalescing Separator

Function: to break emulsified oil and achieve deep oil removal. Principle: emulsified oil droplets are small and carry interfacial charge, so gravity separation alone struggles. As the oily wastewater passes through theKHC coalescing media, the small droplets collide with, wet and merge on the media surface, gradually growing into large, separable droplets that then rise and separate quickly under gravity or cyclonic action. This stage is the critical step that turns invisible oil into visible oil.

Parameters and Performance

With the three stages working together, emulsified oil removal precision reaches0.1 micron, and effluent oil content falls below 10 ppm. A 0.1-micron rating means that even sub-micron emulsified oil can be removed effectively, something conventional flotation, which typically handles droplets of tens of microns and above, cannot match.

Comparison With Conventional Processes

Conventionaloil separation plus flotation works well on free and dispersed oil, but its removal rate for emulsified oil is low; effluent oil content is often in the tens of ppm, with heavy chemical consumption and large sludge volumes. SINOKLE's new process relies mainly on physical separation, with low chemical dependence and stable operation, and effluent oil content drops by an order of magnitude, creating favorable conditions for the downstream desulfurization and deamination steps.

Conclusion: this process is highly feasible and reliable, delivering both environmental and economic benefits. Compared with conventional technology it stands at a domestically leading level, and it is a practical choice for fine oil removal from refinery sour water.