upflow oil-separation filters – colexerReading time:
Fine drops of hydrocarbons (1 to 20 mm) suspended in water are trapped by the media, using the same mechanisms as for suspended solids (see section filtration), and feed a film that gradually migrates towards the upper part of the bed from which it escapes in the form of 0.2 to 2 mm droplets. The solid particles are also trapped and stored but their accumulation gradually affects the coalescence mechanism and the filter has to be washed at regular intervals; in addition, rising velocities must avoid sudden fluidisation resulting in sludge being drawn away.
On the other hand, the wash must allow these to remove the sludge throughout the media.
The value of these filters has been validated in three areas :
- oil removal from condensates (where the oil’s coalescence function must reign supreme) with continuous oil collection;
- oil removal from «oil field water» (where the filtration function can be relatively more important, but limited to cases where the hydrocarbons HC/suspended solids ratio is higher than 5);
- the recovery of organic solvents in some hydro-metallurgical processes includes an extraction stage using a solvent.