Coalescer is a simple, virtually maintenance-free system for separating oil from oily water  utilizing a bed of oleophilic ion exchange resins. Coalescer can be used in petroleum refineries, petrochemical plants and related industries as well as treating ballast water, oil well field produced water and other oily waste waters.

The coalescing system for oil removal consists of special filters, filled with oleophilic resin, in order to reach the requested quality of water, even less than 1 ppm of oil. The oily water passes though a layer of granular resins on which a surfactant has been fixed, which makes them oleophilic.

The hydrocarbons are initially absorbed, building up a film on the
resins surface, then start being released in form of larger drops.
The film is continuously removed and therefore the process can be considered as self-regenerating. The coalescing filter is the most
suitable process for these type of effluents for the following main
it has a high removal efficiency
it is the most suitable process for the removal of oil
  particles with a diameter <15 microns
the effluent can be re-used without further treatment

Moreover, the installation, maintenance and management for these solutions are extremely easier instead of the oil/steam separator.
Coalescing filters are suitable if the content of inlet suspended solids is below 5 ppm. Therefore it is foreseen a basket filter as protection to the coalescing system to remove the suspended materials exceptionally present in the stream.

Normal filtering rate 5-20 m/h   Operating temperature 50-100°C   Suspended solids 5 ppm   Hydrocarbon content, feed 10-100 pm   Hydrocarbon content, outlet 1 ppm   Detection method infrared

Removal efficiency up to 99,9%   No moving parts   High filtering rate, thus limited area requirements   Operation up to 100°C   Long resin life   Possibility of periodical backwash of the resins   No chemicals added, thus no additional sludge build-up neither change of salinity of water   Low cost operation   Simplicity of operation and maintenance