Principle of separation by gravity
Separation by gravity utilses the density difference between two phases (liquid-liquid or liquid-solid). E.g. a globule ofone phase (oil) suspended in the heavier other phase (water) will attain a constant rising velocity when the resistance to motion offered by the other phase is equal to the rising force created by the density difference. Important considerations for a separator using this principle are:
- The distance through which the globules travels before reaching the surface or bottom of the corrugated plate
- The rate at which the globule rises or settles
- Particle size
- Density difference
The theoretically foundation for this separation is Stokes Law (1845)
For efficient operation, the vertical distance to be covered by the globules should be made as short as possible, and the rising velocity should be increased by agglomerating the small globules thus creating larger, faster rising globules.
Any break-up of these globules by even slight, local, or general turbulence, will reduce the efficiency of the separator. Consequently, the flow through the unit and in the upstream piping system should be with minimized turbulence. By using corrugated, parallel mounted plates inclined at 45° or 60°, the separator optimises the conditions of short vertical travel under stable streamlined flow and maximum separating surface area. The plates are used in "counter current" mode.
The water phase flows top-down through the inclined plate pack module. The lighter oildroplets rise to the higher plate and slide up, in counter flow with the water phase, towards the float layer above the plate pack.The heavier particles sink to the lower plate and slide along that plate to the bottom of the CPI unit.
Different separation methods
For different applications separation can result in two, three or four phase.
- 2 Phase; Oil and water
- 3 Phase; Oil, solids and water
- 4 Phase; Oil, solids, gas and water
The Tilted Plate Separator Systems product line holds more separation principles.
Counter current flow
- TPI Tilted plate interceptor (Flat plates)
- CPI Corrugated plate interceptor (Corrugated plates)
- DAG DGF Dissolved Air Flotation
- cfCPI Cross Flow Corrugated Plate Interceptor
- pCPI Pressurized Corrugated Plate Interceptor