Oil separators are used for the clarification of operation waste water containing particulate matters floating up (petrol, light tars, oils) with concentration of more than 100 mg/l.
TECHNOLOGICAL PROCESS SCHEME
TECHNOLOGICAL PROCESS DESCRIPTION
The clarification working mechanism of oil separators is based on the density difference of oil products and water. The oil separator is efficient and suitable for elimination of oil products from waste water but not for clarification from sand and other contaminants. That’s why it is necessary to equip the oil separator with a sand catcher.
Taking into consideration the liquid float regime, all oil separators can be divided into:
- gravity-flowing (clarified waste water is moved by gravity forces acting because of the height difference between entry and exit of the oil separator)
- pressure (waste water is moved by pressure created by pump installed either before oil separator or after it)
- accumulative (firstly, waste water is accumulated in the oil separator case; secondly, oil products are separated from water; thirdly, clarified water is taken to the canalization system either on pattern or for further additional clearing).
Under the influence of gravity forces, (without using any electric equipment) such suspended particles as mud and sand are precipitated and oil products contained in waste water are surfaced in the oil separator. Sludge and film formed after clarification are easily eliminated afterwards.
To intensify the clarification process and to increase the effect, there are thin-layer modules installed in oil separators which intercept ultimate particles of oil products and suspensions. These modules do not need any substitution or regeneration.
The multi-storeyed (thin-layer) oil separator is an improved construction of a horizontal oil separator. It is smaller in size and more cost-efficient.
Precipitation and sedimentation processes in thin-layer oil separators are performed in special zones separated by canted bulkheads. The lower the water layer height, the better the efficiency of this clarification method. Thin-layer oil separators are optimum for clarification of so-called light waste water of oil-processing factories without high-viscosity oil fractions (road tar, bitumen).
Thin-layer oil separators are not exposed to undesirable influence of convection and density transition processes. That’s why the sedimentation process spreads equally over the entire length of construction. The volume utilization coefficient of the thin-layer settler is 80%–85%.
Thin-layer modules divide water flow into thin layers which leads to turbulent reduction. Modules are made of thin sheet material. They can be both smooth and corrugated. It is preferable to apply thin-layer modules of different synthetic materials with oil-receptivity because oil globules will aggregate at the surface. Coalescence.
Separated globules after exit from inter-shelf space fall into the oil separator bay where they surface and are eliminated into drain pots. Sludge falls into adjective part of construction. The high ability of thin-layer oil separators to retain relatively small globules can be explained by the fact that precipitation in the laminar water float regime is performed even when there is no turbulent mixing.
Depending on the quantity and further planned utilization, oil and oil products captured in the oil separator fall into special tare or separating reservoirs where they are additionally precipitated for dehydration.
The oil separator is clarified from sludge using one of the following ways:
- oil separator is dewatered, then sludge aggregated on the bottom is flushed with a water stream to the pit to be further taken away by a pump or water-jet blower.
- sludge aggregated on the bottom of the oil separator under water is pulled to the pit using scrapers. Then it is further taken away by a pump or water-jet blower.
Application of thin-layer oil separators because of their high efficiency gives an opportunity to forget about additional mechanic ways of cleaning waste water for oil processing factories. Clarified waste water with low residual concentration of oil products (approximately 50 mg/l) immediately forwards to physical and chemical clarification.
- The degree of output waste water clarification from oil products reaches 95%
- Easy operation and minimum cheap maintenance
- Oil separators case is made of high-quality materials