Three phases in one machine
According to Flottweg, its Tricanter® it separates solids and two immiscible liquids of different densities continuously, in a single process step. Flottweg lists oil-containing sludge, starch production, the slaughterhouse and rendering industry and food residues among the applications it names. The description concerns the simultaneous separation of solids and two immiscible liquids, not three freely mixable components.
The machine builds on decanter technology. The feed goes into a rotating bowl, and under the influence of high centrifugal forces the solids settle against the inner surface of the bowl. The Flottweg page describes the two liquid phases as being discharged separately, and it does not explain the physics of density sorting beyond this, so the description here stays with what the manufacturer states. Everything here describes the Flottweg design, the source does not claim that every machine sold as a three-phase separator works in exactly this way.
What the scroll does
Inside the bowl sits a scroll, which turns at a defined differential speed relative to the bowl. According to Flottweg, the scroll continuously transports the settled solids to the conical end of the bowl, where they are discharged. Flottweg's differential-speed page explains that this difference between scroll and bowl speed is required to transport the solids that collect on the bowl's inner diameter, a scroll turning with the bowl would have no relative motion to carry them along.
It helps to keep the roles apart. The bowl rotation creates the centrifugal field in which the solids settle. The scroll, running at a speed that differs from the bowl by a defined amount, handles the transport of solids. Flottweg's feature pages also say the adjustable differential speed allows the retention time of solids in the machine to be adjusted, so it is tied to residence time as well as to conveying. The solids outlet at the conical end is a separate discharge path from the liquid discharge.
Light and heavy liquid
The feature that distinguishes a Tricanter from a two-phase decanter is how the two liquids leave. In the manufacturer's description, the light liquid, the one of lower density, flows out unpressurized. The heavy liquid, with the higher density, is discharged under pressure via an adjustable impeller. The sectional drawing caption on the Flottweg page makes the same distinction: the higher-density phase is discharged under pressure, while the lower-density phase flows downwards without pressure.
The adjustable impeller is stepless, and Flottweg says it allows the position of the separation zones to be changed even during operation. The stated purpose is a high degree of separation resolution between the two liquids and the ability to respond to changing product characteristics and feed conditions. The page also says this adjustability lays the groundwork for simple automation of the process.
This adjustment should not be confused with the scroll's differential speed. The impeller concerns the position of the separation zones between the liquid phases, the differential speed concerns how the solids are conveyed and how long they remain in the bowl. The Flottweg pages describe the impeller and the differential speed as separate features of the machine, and a reader of a diagram or a trend should keep them apart in the same way.
Reading a plant diagram
When this Flottweg Tricanter principle is compared with a diagram of that machine, the first useful step is simply to identify three distinct discharge paths: solids from the conical end, light liquid leaving unpressurized, and heavy liquid leaving under pressure via the impeller. Keeping them separate prevents the common mistake of treating the machine as if it had one liquid outlet and one solids outlet.
The manufacturer's overview does not say which stream on a particular site carries which composition, and it gives no setting that suits any particular feed. It also does not supply operating limits or a procedure for adjusting the impeller. Those details belong to the installed machine's documentation and the approved site procedure. A product overview is useful for understanding the layout and the logic of the three outlets, but it is not an operating instruction.