Coalescing oil-water separator

Coalescing oil-water separators are meant to separate oil-water emulsions formed in oil production technology, oil and oil product processing, transportation and storage. They are used to separate and regenerate oil products from process wastewater and water solutions of oil refineries, dewater highly watered oils, treat stratal and bottom waters of oil fields and tank farms, treat ballast and bilge waters of marine vessels, treat wastewater of oil depots, washing and steaming stations, etc. The separators are most efficiently used to separate highly concentrated emulsions; herewith, the main requirement is a high degree of separation and return of the trapped product to production or end products.

The technology is based on the results of the 15-year research of contact coalescence of oil products emulsified in the aqueous medium on the surface of various coalescing materials and nozzles.

15 m3/h
2.0 m
4.0 - 4.5 m
Concentration of oil products in the initial emulsion
50 000 - 300 000 mg/l
Concentration of oil products in the initial emulsion in the treated water
not more than 100 mg/l
Emulsion temperature
20 - 90 °C
Moisture content in the separated product
not more than 1.0%
Type and operating mode

Constructional solution

An independent one-stage reagentless process of emulsion separation with a continuous evacuation of the separated product is a distinctive feature of the developed technological and constructional solutions. The process allows to reject the establishment of gravity separation zones, to reduce plant dimensions by several times, increase the separation efficiency of the emulsion and minimize the moisture content of the separated product. At the same time, high process stability in a wide range of oil product concentrations in the initial emulsion (up to 25-30%) is provided. The residual concentration of oil products in the treated water, as a rule, does not exceed 50-100 mg/l. The efficiency and specific capacity of the separators increases as the temperature and concentration of the processed emulsion increases and the density and viscosity of the separated oil products reduces.

Separators SVN-K are cylinder-conic vertical tanks equipped with coalescing elements, phase interface and temperature sensors, automatic valves and an automatic system providing continuous or periodic operation. They include a precipitation zone of coarsely dispersed mechanical impurities and an initial oil storage tank; as it is filled, the separated oil products are automatically discharged into a storage tank.

The technological scheme of one of the options of the separator use is shown in the picture.

Pic. Technological scheme of automatic drainage and treatment of bottom waters of the tank farm.

1 - group of tanks with similar products; 2 - drainage system; 3 - separator SVN-K; 4 - automatic valves; 5 - phase interface sensors; 6 - automation unit; 7 - underground tank; 8 - trapped product discharge; 9 - trapped product return (option); 10 - treated water outflow; 11 - sludge discharge; 12 - industrial sewage; 13 - technical water supply (option); 14 - pumping of the trapped product into production.

Results of production tests

Table 1 shows the results of production and operational tests of separators in the treatment systems of bottom waters of tank farms with various products (crude oil, petroleum, diesel fuel, jet fuel) as well as in the treatment systems of drainage water of diesel hydrotreating plants, Parex and the separation of oil products from monoethanolamine solutions (MEA) in elemental sulfur production plants.

Results of operational tests of separators SVN-K


Bottom waters of tank farms

Drainage water

15% MEA solution

Petroleum, jet fuel

Diesel fuel

Parex plant

Hydrotreatment of DT L-24/7

Elemental sulfur production

Specific capacity, m3/m2·hour






Oil product concentration, mg/l
-before treatment - after treatment

45-680000 10-36

7080-850000 35-88

2125-250000 10-55





Wastewater temperature, 0С






The developed separators can be used for the establishment of low-waste and non-waste petrochemical production. Their technological parameters allow to provide highly efficient treatment of ballast water of tanker fleet ships and one-stage preparation of highly watered oil at field.

Separators SVN-K have passed a full cycle of research and production tests in the drainage systems of bottom waters of tank farms of oil refineries and oil trunk pipelines, in the treatment systems of process wastewater of petrochemical plants as well as of marine bilge water and oil-depot wastewater.