FRP Lamella Separators

Counter-current (down-flow) lamella plate separators for oil/water and solids separation, built in FRP for hot, corrosive service.

CFD simulation of oil droplets, water and solids in a counter-current FRP lamella separator

How a lamella separator works

Distribute
An inclined distribution plate with metered holes sends the feed down evenly into every plate channel.
Typical process flowOily wastewater: lamella separator, DAF and decanter
Generic flowsheet for illustration. Every Archer system is designed to its own basis; ask us for one drawn for your plant.
Separate
Oil droplets rise to the plate undersides and climb against the flow to the oil layer.
Skim and settle
Oil leaves through a skim trough; solids settle to the hopper.
Discharge
Clean water leaves over an adjustable weir; the interface level is monitored.

See it working before it is built

Before any FRP is laid up, we model the separator with computational fluid dynamics (CFD). The model follows oil droplets, water and solids through the vessel, so we can see where the feed goes, whether every plate channel does its share of the work, and where oil and solids collect.

About four hours of operation in thirty secondsOil droplets (yellow) rise to the plate undersides and build the oil layer at the skim trough; water (blue) moves down the plate channels to the weir; solids (brown) settle to the hopper.

CFD of the lamella separator early in the run, before the oil layer has formed — **Start of the run**Feed spreads across the pack; no oil layer yet.

CFD of the lamella separator after about four hours, with the oil layer built up at the skim trough — **After about four hours**A stable oil layer at the skim trough and solids collected in the hopper.

What we check in the model

Even flow to every plate channel, so the whole pack works and none of it is overloaded
No short circuits or dead zones where the feed bypasses the plates or sits still
Oil droplet and solids capture at the design flow
How quickly the oil layer forms and where it leaves the vessel

Comparing arrangements

Several inlet and outlet arrangements were modelled side by side before one was chosen. Each map shows the water velocity on the centre plane of the vessel: warm colours are fast, dark blue is almost still.

CFD velocity map of the final lamella separator arrangement with even flow through every plate channel — **Final arrangement**Flow spreads across the whole plate pack and leaves evenly.

CFD velocity map of a rejected lamella separator arrangement with dead zones beside the plate pack — **Rejected variant**Part of the pack is bypassed and still zones form beside it.

CFD velocity map of a rejected lamella separator arrangement with recirculation above the plates — **Rejected variant**A large eddy above the pack short-circuits part of the feed.

CFD velocity map of a rejected lamella separator arrangement where the feed jet crosses the plate pack — **Rejected variant**The feed jet cuts across the plates instead of spreading.

CFD velocity section through the lamella separator inlet chamber and plate pack — **Through the inlet chamber**The inlet chamber takes the energy out of the feed before it reaches the plates.

Changes are made on screen, where they cost hours, instead of in a finished FRP vessel.

Structure checked by FEA

The FRP vessel and its steel support frame are modelled in code_aster for every load case: operating, flooded to the rim, maintenance drain, lifting and seismic, including sloshing.