Tackling the Challenge of Heavy Crude Oil Tank Draw-Off Water: SINOKLE's Engineered Application of 'Coalescence + Cyclonic Dissolved-Air Flotation'
In petroleum refining, tank-farm draw-off water is one of the typical hard-to-treat oily wastewater sources. As crude oil becomes heavier and poorer in quality, the oil content of the water accumulated at tank bottoms soars (lingering at several thousand to tens of thousands of mg/L year-round, and even reaching 100,000 mg/L), accompanied by high concentrations of COD and suspended solids.
Traditional sedimentation tanks or chemically dosed dissolved-air flotation often fall into a vicious cycle of 'high energy use, much sludge, and incomplete oil removal', and may even create safety hazards due to failed water seals.
Faced with this industry predicament,how can low-cost, low-risk, high-efficiency reuse be achieved? SINOKLE has delivered a disruptive solution centered on 'high-efficiency coalescence + cyclonic dissolved air'.
Core breakthrough: from 'chemical dependence' to 'physical separation'
Unlike traditional processes that rely on large amounts of flocculant,this pretreatment process consists of a 'high-efficiency coalescingoil separator' and aCDFUcyclonic dissolved-air flotation' unit in series, supplemented by necessary buffering and lift facilities.
The specific flow is as follows:
Equalization and lift:Tank-farm draw-off water first enters a dirty-oil buffer tank for flow regulation and pre-settling, then is pumped by a lift pump into the main treatment line.
Primary treatment (coalescing oil removal):The wastewater enters the high-efficiency coalescing oil separator. Ultra-hydrophilic modified media (modified by atomic layer deposition) change the interfacial energy of oil droplets, causing micron-scale dispersed oil to collide, coalesce into larger oil droplets, and separate by floatation. This stage mainly retains free oil and large suspended particles.
Secondary treatment (cyclonic flotation):The effluent after primary treatment entersCDFUthe cyclonic dissolved-air flotation device. This unit combines cyclonic centrifugal separation with micro-nano bubble flotation to deeply strip emulsified oil and fine suspended solids, further strengthening the oil-water-solid three-phase separation.
Compared with traditional chemically dosed flotation or biochemical pretreatment, this physical combination process shows the following technical characteristics:
Dimension | Technical performance |
Separation mechanism | Purely physical process: no demulsifier, flocculant, or other chemicals are dosed throughout; separation relies on physical coalescence and buoyancy, avoiding secondary interference of chemicals with water quality. |
Treatment efficiency | High-efficiency removal:The two-stage treatment can stably control the effluent oil content atbelow 10 mg/L (for crude oil tank-farm draw-off water), and also shows a significant synergistic removal of SS and COD, providing favorable influent conditions for the downstream biochemical system. |
Product destination | Resource recovery: the separated dirty oil has low water content and can be directly recovered to the crude oil system; the sludge produced is minimal, mainly inorganic impurities, reducing the hazardous-waste disposal load. |
Operational stability | Strong shock resistance: the physical separation mechanism is little affected by water temperature andpH fluctuations; together with an automatic control system it adapts to the intermittent, highly variable water quality of tank-farm draw-off water. |
Footprint and O&M | Compact: skid-mounted modular design with high integration and a clearly smaller footprint than traditional processes; without a dosing system, daily O&M is simplified and labor demand is low. |
Conclusion
For the 'high oil, high COD, hard-to-emulsify' characteristics of refinery tank-farm draw-off water, the physical combination process of 'coalescence + cyclonic flotation' can effectively solve the traditionalsludge disposal problem and operating cost pressure brought by chemical methods. The process logic is clear; through staged separation it achieves efficient oil-water dissociation and has high engineering application value in the field of industrial wastewater pretreatment.
