SINOKLE Desalter Draw-off Water Treatment: Coalescing De-oiler + CDFU Flotation
In the petroleum refining industry, the desalter draw-off water from atmospheric and vacuum distillation units has long been a difficult point in industrial wastewater treatment. This type of wastewater features high oil content, large water-quality fluctuation, high resin and asphaltene content, severe emulsification, and a small oil-water density difference. Conventional processes such as gravity settling, ordinary hydrocyclone de-oiling, and standard membrane filtration generally suffer from poor treatment effect, high operating cost, and difficulty in removing emulsified oil, easily causing the influent oil of the downstream comprehensive wastewater treatment station to exceed limits and directly affecting the stable compliant discharge and water-reuse of the entire wastewater system. To address this industry pain point, SINOKLE (Shenzhen) Technology Co., Ltd. relies on its proprietary patented technology to build a purely physical treatment process centered on the high-efficiency coalescing de-oiler + CDFU hydrocyclone dissolved-air flotation. It offers two application schemes differentiated by influent oil concentration, achieves internationally advanced overall technology, and allows on-line installation and commissioning without stopping production, providing a one-stop solution for refinery desalter draw-off water treatment. The core advantages of the process are as follows:
Multiple separation principles with efficient demulsification and de-oiling, suited to heavily emulsified water quality
This process breaks through the limitation of traditional processes that rely solely on the oil-water density difference for natural settling. It integrates multiple technical principles—coalescence, cyclonic centrifugation, and gas-oil-water three-phase separation—and completes separation by means of multiple density differences among gas-water and oil-gas-water. The de-oiling effect is essentially unaffected by the density of the fouling oil, efficiently solving the severe emulsification problem of desalter draw-off water. For influent oil content of 0.5%–5%, the overall de-oiling rate of the process exceeds 90%, with stable treated effluent oil content below 50 mg/L. At the same time, resource recovery is achieved: the separated crude oil has a water content below 1% and excellent quality, and can be directly sent to the crude-dehydration unit for reuse, creating additional economic benefits for the enterprise on top of compliant wastewater treatment.
Graded process configuration with on-demand selection, covering full-range oil-concentration conditions
Based on on-site water-quality differences, the process is divided into two mature application schemes adapted to different production scenarios. For high-oil, heavily emulsified desalter draw-off water, a combined process of high-efficiency coalescing de-oiler + CDFU hydrocyclone dissolved-air flotation is used: the front-end coalescing de-oiler completes pre-separation of large oil droplets, floating oil, and heavy impurities to reduce the back-end load, while the back-end flotation unit deeply removes emulsified oil and fine suspended solids, with the two stages working together to guarantee treatment effect. For low-oil conditions, it is simplified to a two-stage series CDFU hydrocyclone dissolved-air flotation process—streamlined, smaller footprint, and easier O&M. The two schemes are flexibly selectable, fully covering the desalter draw-off water treatment needs of refining enterprises under different production loads.
Excellent core-equipment performance: anti-clogging, low energy consumption, stable operation
The core units of the process have all undergone structural optimization and flow-field simulation design, with comprehensive performance far exceeding conventional equipment. The high-efficiency coalescing de-oiler adopts a pressurized coalescing structure with dedicated coalescing media, delivering high separation efficiency and strong anti-shock capability; its internal flow channels are self-cleaning, so clogging is unlikely during long-term operation and frequent shutdowns for cleaning are avoided. The CDFU hydrocyclone dissolved-air flotation is a compact structure that relies on the synergy of cyclonic flow and micro-bubbles, requiring no demulsifiers, flocculants, or other chemicals throughout, and strips emulsified oil by purely physical means. This not only reduces chemical costs but also cuts chemical-sludge generation at the source; with low equipment energy consumption, it suits the long-term continuous operation mode of refining enterprises.
Outstanding anti-shock capability, tolerating large water-quality fluctuations
Changes in production load of refining units directly cause violent fluctuations in the oil content and volume of desalter draw-off water—the main reason for effluent exceedance in traditional processes. SINOKLE’s entire process has extremely strong anti-shock capability against water-quality and quantity variations: even if influent oil and suspended-solids indicators fluctuate sharply, the internal flow field and separation system can still operate stably, and the effluent always meets the influent requirements of the downstream wastewater treatment unit. This effectively avoids risks such as whole-line shutdown and excessive discharge caused by water-quality shocks, safeguarding the two-way stable operation of refining production and the wastewater treatment system.
Fully automatic intelligent operation, greatly reducing manual O&M costs
The entire system is equipped with an integrated fully-automatic control system incorporating on-line water-quality, pressure, and flow monitoring instruments, enabling automated management of the whole process of influent, separation, oil discharge, backwash, and effluent, and supporting both local on-site control and remote monitoring. Equipment operating parameters can be automatically adjusted according to influent water quality, requiring no dedicated on-site attendance. Compared with traditional processes that involve high manual-operation intensity and high human-error rates, this process greatly reduces labor input and lowers O&M management difficulty, meeting the intelligent production-management needs of modern refining enterprises.
Fully enclosed pressurized operation: safe, eco-friendly, eliminating on-site hazards
The entire process adopts a fully enclosed pressurized design in which wastewater, waste oil, and waste gas all circulate within enclosed chambers and pipelines, effectively containing the diffusion of volatile hazardous gases and odors outward and thoroughly solving the safety hazards and environmental problems of traditional semi-open processes. Waste gas generated by the system is uniformly collected and sent to the waste-gas treatment system; sludge and backwash water are classified and diverted to the sludge-treatment unit, with no disordered leakage of wastewater or waste gas. The on-site working environment is safe and tidy, fully complying with the safety-production and environmental-control standards of the petrochemical industry.
Skid-mounted integrated design with compact footprint, allowing on-line construction without stopping production
All equipment adopts a skid-mounted integrated layout—compact structure and small footprint—requiring no large civil structures and greatly saving plant-site land resources and infrastructure investment. Assembly, commissioning, and linkage testing are completed before delivery, so on-site only pipe connections and control-system linking are needed for start-up. Its most prominent advantage is on-line installation and phased commissioning while the desalter unit remains in normal production; the construction process does not disturb the operation of the main refining unit, avoiding economic losses from production stoppage and shortening the project implementation cycle.
Purely physical process with zero chemicals, reducing secondary pollution and offering high overall cost-performance
The entire treatment flow is a purely physical separation process that adds no chemicals throughout. Unlike traditional chemical-dosing processes, it generates no large amount of oily chemical sludge, greatly reducing hazardous-waste disposal costs. At the same time, the recovered high-quality crude oil can be re-refined and reused, achieving resource recycling. With reasonable equipment cost, simple O&M, and long service life, combined with multiple advantages of energy saving, chemical saving, and revenue increase, the project’s whole-life-cycle cost-performance is significantly higher than that of traditional treatment processes, delivering both economic and environmental benefits.
Mature technology with rich implemented cases and strong application reliability
To date, this process has been implemented and applied in multiple large petrochemical and refining enterprises. Typical projects include the crude-oil de-salter drainage de-oiling skid project of PetroChina Yunnan Petrochemical’s atmospheric-vacuum unit (treatment capacity 105 m³/h) and a large Shandong petrochemical desalter wastewater treatment project (treatment capacity 30 m³/h). Multiple projects have been verified by long-term continuous operation, with stable treatment effect and low equipment failure rate. The technology maturity and site adaptability have been fully recognized, making it a mature preferred scheme for desalter draw-off water treatment in the refining industry.
Summary
The SINOKLE desalter draw-off water treatment scheme centers on two patented core devices—the high-efficiency coalescing de-oiler and the CDFU hydrocyclone dissolved-air flotation—and combines multiple advantages such as graded process design, purely physical separation, automatic control, and enclosed skid-mounted integration to comprehensively solve the industry pain points of traditional processes: difficult emulsified-oil removal, poor anti-shock capability, easy clogging, cumbersome O&M, and large safety/environmental hazards. The process not only stably treats desalter draw-off water to compliant status and ensures the smooth operation of the downstream wastewater treatment system, but also recovers high-quality crude oil for resource reuse, delivering both environmental and economic benefits. Meanwhile, the equipment can be installed on-line without stopping production, runs fully automatically, and is safe, enclosed, and eco-friendly—perfectly suiting the continuous, intelligent, and green production requirements of petrochemical and refining enterprises. It is an advanced, reliable, and cost-effective integrated solution for oily wastewater treatment in atmospheric-vacuum desalter draw-off water today.
