Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/934530
20 | January - February 2018 | www . machinerylubrication.com Using Centrifugal Separators for Oil Reclamation OIL RECLAMATION Stephen Chastain | US Filtermaxx Oil reclamation offers a number of economic benefits. For instance, if oil that is discarded and replaced could be cleaned and put back into operation, tens or hundreds of thousands of dollars could be saved every year. is type of cleaning process frequently involves a centrifuge. Centrifuges work on the principle of high gravity. In short, anything that is heavier than the fluid will be forced out, regardless of size. With these devices, even small differences in specific gravity are amplified to such a degree that submicron particles quickly settle out. Centrifuges can break emulsions and remove particulate, including graphite, but they will not eliminate particles held in suspension by Van der Waals forces. Types of Centrifuges ere is no shortage of centrifuge designs. e variations generally are based on the type of contami- nation involved. For particulate cleaning and light water removal, a bowl type of centrifuge is a good option. When there is heavy water contamination, a tube type of centrifuge is more appropriate. For oils that have both water and particle contamination, a more complex centrifuge may be needed to remove and dump solids while separating the water. Unfortunately, the more complex the centrifuge, the higher the cost. A bowl centrifuge spins the oil, with particulate settling out against an inside wall of the bowl. A layer of water forms on top of the hard particles, followed by a layer of water/oil emulsion and then a layer of oil that progressively becomes cleaner toward the center of the bowl. e clean oil will spill over the bowl's top edge and drain from the centrifuge. ere are also a few variations on the solid bowl design. For high solids and gentle acceleration, an open bowl containing no vanes or plates is used. Frequently, this is a biological type of bowl that does not rupture cell walls. However, some applications may require minimum shearing because of delicate polymers contained in the fluid. A high solids biological type of open bowl may be used in these situations. A high solids bowl will also be open with no plates but may have vanes to provide more acceleration to the fluid, forcing it deep into the bowl. No plate is used to make removal of the solids easier. For difficult cleaning jobs, a plate is added to the high solids bowl to force fluid to the outer wall so maximum G-force can be exerted. e area for solids collection is reduced by the plate. is type of bowl should be cleaned before the solids block off the plate e longer the oil remains in the centrifuge, the better the cleaning will be." " An example of a plate type of bowl