Oil-water separation is mainly based on the difference in density of water and oil or chemical properties, using gravity sedimentation principle or other physical and chemical reactions to remove impurities or complete the separation of oil and water.
The oil-water separation methods mainly include gravity separation, centrifugal separation, electrical separation, adsorption separation, air flotation separation, etc.
1. Gravity separation:
Due to the different relative density of oil, gas and water, a certain mixture of oil and water at a certain pressure and temperature will form a certain proportion of oil, gas and water phase when the system is in equilibrium. When the relatively light component is in the laminar flow state, the heavier component droplets settle according to the motion law of the Stokes formula, and the gravity sedimentation separation device is designed according to this basic principle.
2. Centrifugal separation
By using different oil-water densities, the high-speed rotating oil-water mixture produces different centrifugal forces, thereby separating the oil from the water. Since the centrifugal device can reach very high rotational speeds, generating centrifugal forces of up to several hundred times the gravitational acceleration, the centrifugal device can completely remove the oil moisture and requires only a short residence time and a small equipment volume.
3. Electrical separation
As the final means of oil-water treatment, electro-evaporation is widely used in oil fields and refineries. The principle is that the emulsion is placed in a high-voltage alternating or direct current electric field. Due to the effect of the electric field on water droplets, the interfacial film strength of the emulsion is weakened and promoted. The collision and coalescence of water droplets eventually coalesce into water droplets with larger particle diameters and separate them from the crude oil.
4. Coarse granulating evaporation of emulsified water
Different kinds of solid materials of hydrophilic eucalyptus oil are used to make various evaporation devices by utilizing the difference in the affinity of the oil and water for the solid matter. Solid materials used for oil-water separation should have good wettability.
5. Air flotation separation
The air floatation method is a method of forming tiny bubbles in water and carrying the floc floating up to the liquid surface to purify the water. The condition is that bubbles attached to the oil droplets can form oil and gas particles. Since the occurrence of bubbles causes the density difference between the water and the particles to increase, and the particle diameter is larger than that of the crude oil droplets, the increase in the density can be significantly improved by using the particle density instead of the oil density.