Process Breakdown: Crude Oil Tank Farm Cut Water Treatment — Two-Stage Synergy of CDFU Flotation and the HCC Cyclonic Coalescer

Cut water treatment in crude oil tank farms is widely acknowledged as one of the hardest problems in refining and petrochemical water treatment: the oil content is extremely high (it can reachmore than 100,000 mg/L) and the emulsification runs deep, so conventional processes struggle to meet discharge limits consistently. This article breaks down the two-stage, purely physical separation process introduced by SINOKLE —CDFUcyclonic dissolved air flotation plus the HCC high-efficiency cyclonic coalescer — as a reference for industry peers.

1. Stage One:CDFUCyclonic Dissolved Air Flotation — Microbubble Flotation Tackling High-Concentration Emulsified Oil

CDFU draws its core capability from bubble generation and oil capture. The dissolved-air system dissolves air into the water under pressure, and a release device then abruptly depressurizes it, producing microbubbles that are extremely fine and enormous in number. Once these bubbles enter the oily water, they collide with and adhere to emulsified oil droplets, forming bubble-and-droplet aggregates. Because the density of such an aggregate is far lower than that of water, buoyancy carries it quickly to the surface, where it forms a floating oil layer that is collected by the skimming device. The cyclonic structure further intensifies flow-field disturbance and raises the collision probability between bubbles and oil droplets, markedly improving the removal efficiency of microbubble flotation on high-concentration emulsified oil.

2. Stage Two:HCC High-Efficiency Cyclonic Coalescer — Coalescing Separation That Polishes Off Residual Fine Droplets

After first-stage flotation, most of the emulsified oil has been removed from the water, yet a small amount of fine oil droplets still remains.Polishing is exactly what the HCC is for. Once the oily water enters the HCC, it rotates at high speed inside the cyclonic field and centrifugal force drives the oil droplets toward the centre; at the same time the water passes through the coalescing media, where fine droplets wet and adsorb onto the media surface, colliding and merging continuously into larger droplets that finally rise and separate rapidly under buoyancy. This dual mechanism of cyclonic separation plus coalescence pushes the oil content of the second-stage effluent lower still, providing assurance for compliant discharge.

3. The Two-Stage Synergy: Flotation Leads, Coalescence Polishes, Forming a Complete Removal Chain

The two stages are not merely connected in series; they form a synergistic system with a clear division of labour:CDFU handles the main separation of high-concentration, heavily emulsified cut water, lifting the overwhelming majority of oil and suspended solids out of the water and sharply reducing the downstream load; the HCC then applies deep coalescing separation to the fine oil droplets remaining in the flotation effluent, keeping effluent quality stable. The first solves the problem of quantity, the second the problem of quality. Tightly linked, the two stages form a complete removal chain that runs from oil contents on the order of 100,000 mg/L all the way to compliant discharge.

4. Comparison with Conventional Processes

5. Summary of Application Value

Viewed in terms of process completeness,CDFU+HCC two-stage purely physical separation delivers stable treatment of highly oily, heavily emulsified cut water: the effluent meets discharge standards and satisfies environmental requirements; recovered oil goes straight back to the crude oil tank, turning waste into value; and the whole process runs on zero chemicals with no secondary pollution, sidestepping the twin burdens of chemical dosing and hazardous waste disposal. For tank farm operators that weigh environmental compliance and resource recovery equally, this process offers a workable and sustainable technical option.