The WaterWall® unit utilizes a proprietary “filtering media” that blocks non-miscible liquid(oil) droplets while permitting other liquid(water) stream to pass through. The blocked small oil droplets coalesce together to form large droplets until they have enough buoyancy.
Automatic pre-activation of the filtering media creates a strong interfacial film that inhibits the passage of the dispersed phase under controlled flow rate. The droplets of the dispersed phase are coalesced while being repelled from the “filtering media”, forming a layer that is continuously skimmed out recovering the dispersed fraction.
A typical WaterWall® system, where the two successive stages are intended to exploit both the deep bed coalescing effect on the first, coarser two-phase filtering layer, and the rejecting barrier of additional interfacial tension generated, at different levels, both on the first and on the second, finer two-phase filtering layer.
The first stage - Coalescing: small oil droplets should pass through coalescing filter to become bigger.
The second stage - WaterWall®: most of oil droplets cannot pass through hydrophilic diaphragm in WaterWall®
 Rejected oil is recovered from the top of both separation chambers. Level controls operate in order to maintain the pressure level on the two-phase filtering layer within the desired range: this range allows the plant to deal with sudden reductions in the incoming flow rate, as well as with a sudden increase in oil concentrations with no effect on the separation efficiency of the system.
WaterWall® can obtain a virtually complete separation of the inflow oil > 99.9% by removing oil droplets up to 0.3 µm.
 Typical oil droplets distribution
Owing to the physics of the separation system, the correct determination of the water velocities on the top of the two-phase filtering layer plays a key role at design level. Numerical techniques simulate water flows inside standard and custom-made WaterWall® configurations. (Click images for bigger size.)
  |
 
|
|