How CDFU Works and Its Advantages
Working principle
The compact cyclonic flotation separator (CDFU) is patented equipment with independent intellectual property rights owned by SINOKLE. Building on advanced international technology, the product innovatively combines cyclonic centrifugal separation with dissolved gas flotation and is deeply optimized through computational fluid dynamics (CFD), resulting in an internationally advanced, highly efficient oil-water separation solution. Its unique cyclone design significantly enhances bubble flotation performance and greatly shortens the retention time required for flotation, achieving fast and efficient oil separation. The unit is widely applicable to industrial wastewater containing oil and suspended solids.
Flotation principle
Flotation technology introduces large quantities of highly dispersed microbubbles into the water to be treated (coagulants or flotation agents are usually dosed), so that they act as carriers, adhering to particles suspended in the water (oil droplets) or flocs, to form a float whose overall density is lower than water, rising together to the surface under buoyancy, to form scum that is removed — a water purification technique that separates solid from solid, solid from liquid and liquid from liquid in water.
(1) Flotation separation involves three processes: bubble generation; bubbles and suspended solids (particles or oil droplets) attachment; bubbles carrying suspended solids (particles or oil droplets) rise to the liquid surface and coalesce for removal by a skimmer.
(i) Bubble generation methods. i. Dissolved gas method: small bubble diameter (20-100μm), bubble-water contact time can be controlled, and bubbles can be generated by pressurized dissolved gas or multiphase pumps. ii. Diffused gas (dispersed gas) method: larger bubble diameter (100-10000μm), produced by ejectors, fine-pore diffusers and impeller agitation. iii. Electrolysis: small bubble diameter (10-60μm), but high power consumption, easy scaling of electrodes and difficult operation. iv. Electrostatic spraying gas method.
(2) Bubble attachment to suspended solids. Microbubbles have a natural adsorption affinity for hydrophobic suspended solids and oil droplets, and the interfacial energy decreases after attachment. Contact angle: when gas, liquid and solid phases contact each other, the angle at the gas-liquid interfacial tension line and the solid-liquid interfacial tension line ((facing the liquid phase) ) is expressed as θ. Hydrophilic: substances easily wetted by water, θ<90. Hydrophobic: substances not easily wetted by water, with θ>90. At the three-phase contact point, the interfacial tensions are in equilibrium:
(3) Bubble-suspended solids separation process. Bubbles adhere to suspended solids (oil droplets) and gradually form scum that rises to the gas-liquid surface of the wastewater, where bubbles break and release the gas; the pollutants gather and coalesce into masses discharged through the sludge outlet.
CDFU Principle of the
Wastewater to be treated enters the CDFU unit and is first thoroughly mixed in a mixer with fine bubbles (5~30 μm diameter) released from dissolved gas water. The mixture then enters the main unit tangentially along the vessel wall, forming a high-speed cyclone. Under strong centrifugal force, microbubbles and emulsified oil droplets are rapidly driven toward the cyclone centre and gather, forming scum. The separated gas (such as nitrogen) exits with the scum from the top outlet into a dedicated collection tank, where the gas is separated and vented, while the treated clean water flows downward and is discharged from the bottom outlet.
Structural features
(1) Greater centrifugal acceleration and more stable cyclone flow favour interaction between bubbles and oil droplets, accelerating their coalescence toward the cyclone centre, improving flotation performance, shortening retention time and allowing a more compact structure. Shock resistance is stronger, accommodating a turndownturndown rate variation of 50%50
(2) Dual flotation zone design. A central cylinder is arranged at the centre of the flotation vessel, dividing it into an inner flotation zone inside the cylinder and an outer flotation zone outside it. The inlet enters the inner cylinder tangentially, generating greater centrifugal force and centrifugal acceleration, better favouring the gathering of bubbles and oil droplets toward the centre and improving flotation performance. The inner and outer cylinder design refines the flow of wastewater within the vessel, forming distinct flotation zones, avoiding oil droplet entrainment in the effluent that would reduce flotation performance, while achieving higher space utilization and a more compact structure.
CDFU (3) Cyclone desanding design. The conical bottom of the central cylinder provides a desanding effect. Larger and heavier particles are gradually thrown to the inner cylinder wall under centrifugal force and flow downward along the wall into the conical zone, always maintaining cyclone flow so that sand does not accumulate easily and is easier to remove. Periodic fluidized sand discharge prevents clogging.
Technical features of the CDFU
● Excellent separation efficiency: slop oil removal efficiency of no less than 90%, far higher than conventional IGF.
● Extremely low operating energy and gas consumption: low energy consumption (10% of the energy) and low gas consumption (1% of the throughput).
● Economical overall operating cost: small chemical dosage, low sludge generation, low operating and maintenance costs.
● Stable operation and strong adaptability: stable performance, accommodating a flow variation range of 120%.
90%, far higher than conventional IGF10%IGF Extremely low operating energy and gas consumption: 1%-3%low energy consumption (
10%of the energy) and low gas consumption (
