Liquid purification or separation – Processes – Separating
Reexamination Certificate
1999-08-20
2001-03-13
Upton, Christopher (Department: 1724)
Liquid purification or separation
Processes
Separating
C210S801000, C210S521000, C210S540000, C210SDIG005
Reexamination Certificate
active
06200490
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to liquid purification systems and more particularly to a system and method for removing free oil from coolant utilized in industrial machining applications.
Industrial machining operations generally require the use of coolants to prevent damage to tools and minimize wear caused by excessive heat. Typically, a coolant comprises an oil-in-water emulsion wherein water is the continuous phase, oil is the disperse phase, and soap is the emulsifying agent.
The oil-in-water emulsion is stabilized by electro-mechanical forces which are weakened or destroyed by contaminants in the form of metallic ions, free oil and bacterial action. The primary culprit in coolant deterioration is free or “tramp” oil which must be removed to maintain the stability and equilibrium of the emulsion.
SUMMARY OF THE INVENTION
The aforesaid problem is solved, in accordance with a preferred constructed embodiment of the pre sent invention, by an improved free oil separation system and method that removes free oil from an oil-in-water emulsion. The oil separation system is disposed downstream of the machining process to accept contaminated coolant produced during the machining operation.
The oil separation system and method of the present invention comprises a plurality of spaced polymeric elements, for example polypropylene tubes, that are positioned above a primary settling chamber. Contaminated coolant flows through the elements without restriction. Oleophilic surface attraction between the polymeric elements and free oil in the coolant attracts and binds the free oil to the walls of the vertically oriented elements where further coalescing of the free oil occurs. The coolant and coalesced oil globules then flow out of the polymeric elements and into a primary settling chamber where gravitational separation of the free oil from the coolant occurs.
Coalesced free oil globules rise upwardly, passing over a primary oil weir and into a secondary settling chamber. Partially cleansed processing fluid is directed beneath a primary coolant baffle thence over a primary coolant weir where free oil again rises and flows into the secondary settling chamber. A primary decant chamber, separated from the secondary settling chamber by a decant chamber wall, is provided with an outlet conduit to allow purified coolant to flow back to the system. Once in the secondary settling chamber, partially cleansed coolant flows over a secondary fluid weir where a second outlet conduit which is opened and closed by a normally open outlet valve is provided to return the remaining purified coolant to the system.
Free oil decanting is accomplished by closing the normally open outlet valve until the coolant and free oil level in the secondary settling chamber rises to the level required to allow free oil on the surface thereof to flow over a waste oil weir into a waste oil chamber. The waste oil chamber is provided with a waste oil conduit that allows for decanting of free oil. The waste oil chamber is further provided with a bottom that prevents separated free oil that flows over the waste oil weir from draining back into the secondary settling chamber.
The aforesaid operation is controlled by a timer that provides for a predetermined waste oil removal period during which the normally open outlet valve is energized closed thereby raising the free oil and coolant level in the secondary settling chamber to allow free oil to flow over the waste oil weir for decanting. By adjusting a fluid inlet valve that controls coolant and free oil flow into the inlet plenum, flow through the separator may be limited such that the total flow through the secondary settling chamber is five to ten percent of the total flow through the entire system.
This flow limitation allows for maximum efficiency in free oil separation and decanting. Furthermore, the use of flow limited multistage gravitational separation eliminates the necessity of employing a surface skimmer to remove free oil from the surface of the oil-in-water emulsion. Known in the art surface skimmers often suffer from the disadvantage that they remove large quantities of coolant mixture from the system, in addition to surface resident free oil, thereby providing for inefficient separation of free oil from coolant.
Therefore, one object of the instant invention is to provide an oil separation system and method that collects and decants a greater concentration of waste oil than known oil separators.
A further object of the present invention is to provide an oil separation system and method that decants waste oil without employing inefficient surface skimmers.
Further objects, features and advantages of the instant invention will be readily apparent from the following detailed description thereof with reference to the accompanying drawing Figures and claims appended hereto.
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Lyon PC
Upton Christopher
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