HCC High-Efficiency Cyclonic Coalescing Unit: An Outstanding Oil–Water Separation Solution
Produced water from oilfields has a complex composition, covering dissolved hydrocarbons, gases (such as hydrogen sulphide and carbon dioxide) and organic acids, which makes treatment quite challenging. Besides produced water, oil and gas production also generates drilling wastewater, well-washing return fluids and gas-production wastewater. At the same time, refineries discharge large volumes of oily wastewater in production, which can be divided by process into desalter effluent, sour process wastewater (from atmospheric and vacuum distillation, fluid catalytic cracking and hydrotreating) and spent caustic liquor. To deal with this, the oil–water treatment methods commonly used today include filtration separation, membrane technology and gravity settling. Filtration, however, is often troubled by clogged screens or membranes and normally requires a backwashing system and periodic replacement of filter media, which makes maintenance cumbersome; membrane technology suffers from high investment cost and limited treatment capacity, and in oily media is prone to membrane fouling or deformation that degrades treatment flux, separation performance and service life; gravity settling equipment requires a long residence time and a large installation area.
Centrifugal separation, a process that separates and classifies media on the basis of density difference, offers the advantages of a simple structure, a small footprint and easy operation and maintenance. A typical cyclone consists of four parts — the main body, the tangential inlet, the vortex finder and the underflow outlet — and works through centrifugal force: the heterogeneous mixture is injected tangentially into the unit under pressure and forms a high-speed rotating flow field inside the swirling chamber. In this process the denser aqueous phase, driven by centrifugal force, moves axially toward the bottom and, because of its marked inertia, is accelerated radially, gathers near the cone wall and is finally discharged through the underflow outlet. The lighter oil phase, less affected by inertia, gradually migrates toward the central axis of the unit and is then led out through the overflow, achieving effective two-phase separation. Conventional cyclonic equipment, however, has separation limits when treating fine oil droplets, and modern industrial development urgently needs separation technology that can run continuously, is economical and efficient, offers outstanding precision and provides considerable throughput.
Figure. Structure of a conventional cyclone
The HCC high-efficiency cyclonic coalescing unit launched by SINOKLE innovatively integrates super-oleophilic hydrophobic coalescing fibre material, cyclonic centrifugal technology, wetting coalescence, collision merging and interception filtration, significantly improving the demulsification performance on emulsified oil and achieving rapid capture and separation of suspended solids. The technology combines cost economy with high separation efficiency. The core of the unit consists of the inlet chamber, the spiral guide channel, the equal-diameter cylindrical coalescing chamber, the coalescing core unit and the outlet pipeline. Its working process is as follows: after the oil–water mixture enters the unit, it is guided by the spiral channel and the flow pattern changes from axial to tangential, and at this stage the fine oil droplets already begin to collide and aggregate. At the end of the spiral channel the mixture forms a tangential swirling environment; on the one hand it moves as a whole along the coalescing chamber toward the outlet under the driving force of inlet pressure, and on the other hand, because of the change in flow pattern, the liquid travels axially inside the coalescing chamber while rotating around the coalescing core.
Figure. Schematic structure of the high-efficiency cyclonic coalescer
Based on the density difference between oil and water, inside the equal-diameter cylindrical coalescing chamber the oil droplets move radially from the wall toward the axis and, because of differences in droplet size, spatial distribution and residence time, exhibit tangential, radial and axial velocity gradients in the swirl field. This drives collisions between micron-sized droplets, between small droplets and larger droplets, and among large droplets, so that small droplets merge into large ones while continuing to rotate around the core as they travel toward the outlet. Since the outlet of the unit is connected to the inlet of the cyclone, the oil–water distribution pattern is optimised after this pre-treatment — the oil phase concentrates on the inner side while the aqueous phase remains on the periphery, and the oil droplet size increases markedly, greatly shortening the separation time of the downstream cyclone. This effectively solves the pain point of insufficient separation of fine oil droplets in conventional equipment and comprehensively improves the separation efficiency of the system.
Engineering application examples of the SINOKLE HCC high-efficiency cyclonic coalescer:
Coking wastewater treatment site of a refining and chemical enterprise
The treatment performance of the SINOKLE HCC high-efficiency cyclonic coalescer is as follows:
Inlet and outlet water comparison
Verified by actual engineering practice, the SINOKLE HCC high-efficiency cyclonic coalescer offers the following advantages:
The particle size of emulsified oil removed is small (emulsified oil above 0.1 μm is completely removed), and the emulsified oil removal efficiency is high;
Short residence time (<3 min), small equipment footprint and skid-mounted availability;
Strong impurity tolerance and effective removal of suspended solids, fundamentally overcoming the clogging problem of conventional filter-cartridge coalescers, with wide adaptability;
Specially modified super-oleophilic hydrophobic reinforced fibre material that resists fibre breakage and ageing and offers strong corrosion resistance; modular filter cartridge design for simple and quick replacement;
Cartridge service life of 2–5 years, 2–5 times that of conventional coalescing elements;
Fully enclosed automatic operation: safe, environmentally friendly and requiring little manual work.
