Working Principle of a Purifier
Liquids with a specific gravity or density difference can be separated in a setting tank by the effect of gravity. The centrifugal separation of two liquids, such as oil and water, results in the formation of a cylindrical interface between the two. The positioning of this interface between the centrifuges is very important. With reference to the section view, the heavy bowl and the stack of conical disks that it contains are rotated by the spindle, which is driven at high speed through gearing by the electric motor visible in the photograph. Untreated oil flows in at points and is directed to the bottom of the bowl. Holes in the disks allow the oil to flow upward through the stack. The rapid rotation of the disks and bowl spins the mass of oil. Since the water and sludge are heavier than the oil, they are outward by the centrifugal force, while the oil remains nearer the center. Sludge accumulates on the inside periphery of the bowl, and water, just inside of the sludge. The water passes toward outside the outer edge of the disk stack and exits at point 5. The top disk directs clean oil toward the center, and the clean oil exits at point 4. Like most modern oil purifiers, the unit in these figures is said to be self-cleaning or sludge-ejecting: the bottom of the bowl can move down slightly, but is normally forced upward against the upper part of the bowl by water introduced under pressure at point 7. At timed intervals while the purifier is running, this water pressure is interrupted momentarily and accumulated sludge is forced out by centrifugal force through ports in the bowl at point 3. Purifiers that are not self cleaning must be disassembles and cleaned by hand frequently. Even self-cleaning purifiers must occasionally be cleaned manually.
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