API and corrugated-plate (CPI) separators — the gravity first stage that removes free oil and coarse solids from produced water.
Produced-Water Deoiling — in depth
Gravity separation is the workhorse first stage of produced-water deoiling. API basins and corrugated-plate interceptors (CPI) exploit the density difference between oil, water and solids; plate packs shorten the rise distance so free oil droplets coalesce and rise faster, removing the bulk of free oil before finer polishing.
What matters in practice
Density difference floats oil and settles solids.
Plates cut droplet rise distance for faster separation.
Removes bulk free oil to ~50–150 mg/L.
Heavy solids drop to a sludge hopper.
| Parameter | Typical | Note |
|---|---|---|
| Inlet oil | >1000 mg/L | Free oil |
| Outlet oil | 50–150 mg/L | Before polishing |
| Droplet cut | >100 µm | Free oil only |
| Stage | Primary | Ahead of flotation |
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