Dissecting SINOKLE's CDFU Cyclonic Dissolved-Air Flotation + Coalescing Oil Separator Package: How a Pure-Physical Method Squeezes 105 m³/h Oily Wastewater Below 150 mg/L?
In a deoiling project for desalter effluent from the atmospheric/vacuum unit at a PetroChina refinery in Southwest China, Shenzhen SINOKLE delivered a set of"coalescing pressure oil separator+ CDFUcyclonic dissolved-air flotation (CDAF)"combined skid-mounted package. The core highlight of this package is not its scale——105 m³/h(which is not large in the petrochemical industry)——but rather"the pure-physical-method"logic behind these three words.
This article gives an equipment-level technical breakdown.
I. Process Route Overview
The whole package adopts a two-stage series structure:
Stage 1: Coalescing Pressure Oil Separator——handles coarse separation — large free oil and dispersed oil.
Stage 2:CDFUCyclonic Dissolved-Air Flotation (CDFU)——handles fine separation — emulsified oil and fine droplets.
No dosing point between the two stages. The whole process is purely physically driven.
II. Coalescing Pressure Oil Separator: Letting Oil Droplets"'Grow by Themselves'"
Coalescence (Coalescence) is not complicated: oily wastewater passes through a bed packed with specific material; tiny droplets are captured by the surface, held, and collide and merge with later droplets as they travel the tortuous channels, finally growing large enough to detach and rise under gravity or buoyancy.
But the engineering difficulties of this equipment lie in three points:
First, selection of coalescing media. Different materials' surfaces are oleophilic/or oleophobic to different degrees, and coalescing efficiency for specific oils varies markedly. SINOKLE customizes the coalescing medium based on petrochemical oil characteristics.
Second, balancing flow velocity and residence time. Too fast and droplets can't collide and merge in time; too slow and capacity suffers. Being able to105 m³/hmake the coalescer work effectively at the total treatment capacity is the core hydraulic-design challengeknow-how。
Third, the requirements for the pressure vessel. The coalescer runs under pressure; the equipment's sealing and strength design directly determine safety.
III.CDFU: Four Technologies Cooperating in One Cavity
CDFUFull name:Cyclonic Dissolved Gas Flotation Unit——Cyclonic Dissolved-Air Flotation unit, a patented SINOKLE product and China's first enclosed pressurized flotation technology. Rather than adding a cyclone onto a conventional flotation tank, it redesigns the separation chamber from the fluid-dynamics level.
The four coupled technologies, analyzed layer by layer:
3.1 Cyclonic centrifugal separation
Oily wastewater enters tangentiallyCDFUthe cavity, forming a high-speed swirl in the cylindrical separation zone. By the centrifugal variant of Stokes' law, oil droplets (density<less than water) migrate toward the axis in the centrifugal field. Separation efficiency is proportional to the square of swirl intensity——This isCDFUthe physical basis for higher efficiency than conventional gravity flotation.
3.2 Ultra-fine bubble generation
This isCDFUthe core technical barrier distinguishing it from conventional flotation. SINOKLE uses proprietary dissolved-air release technology: pressurized dissolved-air water is instantaneously depressurized through a special releaser, generating large numbers of micron-scale bubbles.
Why is bubble size so critical? The smaller the bubble, the larger its specific surface area and the higher the collision probability with oil droplets, and the slower a single bubble's rise velocity (per Stokes' law), so its"'sweeping'"time in water is longer. Conventional flotation bubbles are usually millimeter-scale,CDFUso micron-scale bubbles are equivalent to raising"the 'capture net's'"mesh density by orders of magnitude.
3.3 Dissolved-air flotation
After micro-bubbles collide with oil droplets, a stable attachment forms at the oil–water–gas interface. The bubble lowers the droplet's overall effective density, letting the droplet–bubble aggregate quickly float to the surface.CDFUThe enclosed pressurized design ensures the whole flotation proceeds in a stable pressure field, avoiding bubble escape and scum-layer destruction caused by surface fluctuation in conventional open flotation tanks.
3.4 Coalescent demulsification
CDFUInternally integrates a coalescing unit so that tiny droplets not captured by the previous three stages collide and merge while passing the coalescing media. Put vividly: the cyclone throws out"what it can fling out,"the bubbles stick on"what they can stick to,"and the coalescer grows"what neither can fling out nor stick to —""nurtures it bigger"and then sends it back to the first two stages.
IV. The Coupling Logic of the Four Technologies
The core value of this combination lies not in any single technology but in synergy.
The logic of conventional processes is"'series':"——gravity separation, then flotation, then filtration — each independent, each managing its own segment.CDFUSINOKLE's logic is"'fusion':"——in one cavity, the cyclone creates a centrifugal-force gradient, bubbles create a buoyant-force gradient, and coalescence creates a size gradient; the three gradient fields superimpose to capture oil droplets of different sizes simultaneously.
The result: processing efficiency rises while equipment volume is greatly compressed. This is why105 m³/hSINOKLE can skid-mount this capacity — the physical premise——whereas conventional schemes need ponds of hundreds of square meters to match it.
V. Key Process Parameters
Although SINOKLE has not disclosed detailed equipment design parameters, several key indicators can be extracted from the delivered project results:
· Treatment capacity:105 m³/h
· Effluent oil content:<150 mg/L(meets discharge standard)
· Operation mode: no dosing throughout, pure-physical method
· Oily-waste recovery: separated oil can be re-refined
· Waste: no oily sludge generated
The commercial logic of this package is clear: it cuts the recurring chemical-cost line and the hazardous-waste-disposal compliance-cost line, while compressing the construction period from half a year to months. For refinery operators, it is a win–win–win proposition.
