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Separation of the solids occurs as a result of adhesion to the tramp oil, floating up of very small particles or sinking of heavy particles. In the development of the separator our attention focused on the much more difficult problem of achieving optimum separation of minute oil droplets from the water (or from the emulsion/solution): We make use of the upward force of the oil, which is dependent on its lower density in relation to the density of the water or the emulsion/solution. To achieve the desired effect, it is necessary to produce the appropriate relationship between the upward forces - produced by density differences and droplet sizes - and currents, fluid friction and volumes. In our mobile unit, separation is carried out through several process stages. |
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In the 1. stage of our separator and the following main separation chamber, oil droplets are separated out and allowed to float to the surface. The separated oil then flows off through an oil overflow.
2. Coalescence
The separation is greatly assisted in the second separation stage
by means of the extremely large surface of the material being
processed in the coalescence basket. The higher viscosity of the
oil and the surface tension differences have a strong braking
effect on the flow speed of the oil droplets in comparison to
the flow speed of the water at the surface of the coalescence
unit. The small oil droplets remaining from the preliminary separation
stage collect at the surface of the processed material, where
they combine together into larger drops, becoming more buoyant.
They can then rise to the surface.
3. Flow Separation
When two mixed fluids flow through a material with a large surface,
neither of the two fluids flows as fast as it would on its own.
In the two phase oil/water system (dispersion) this difference
in flow speed between oil and water increases constantly as the
oil proportion is reduced.
By fitting the separator with appropriate equipment, the additional delay of the oil proportion at the coalescence units is used to separate off even microscopic oil droplets.
