Liquid purification or separation – With movable support
Reexamination Certificate
2001-06-22
2002-05-21
Lithgow, Thomas M. (Department: 1724)
Liquid purification or separation
With movable support
C210S167050, C210S532100, C210S120000, C210S436000, C210S258000, C210S259000, C210S416100, C210S299000
Reexamination Certificate
active
06391198
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to oil-water and emulsion separation systems, and more particularly, to a system which includes components that are placed in an oil-contaminated water-based system and arranged in series with sludge or oil removed first, and then secondarily, oil, oil removal, and finally a relatively pure aqueous solution results, and this solution is returned to the system. The unit is useful with parts washers and other forms of apparatus which use water and are contaminated by free oil as at least a part of their process fluids. Preferably, the system conveniently uses the same transport containers in which oil, soap or other component is supplied as an integral part of the removal system.
The term “washing fluid” is intended to be an all-inclusive term, which includes water, any number of emulsifying agents, cutting oils, lube oils, way oils and lubricants of various kinds, additives, as well as impurities created by cutting, drilling or other machining operations, including grinding or abrasive metal reduction. The term also includes fluids not strictly used for washing, but which are nonetheless subject to oil/water separation, such as those used in aqueous-based parts washers. For purposes of illustration, however, the description herein is primarily directed to those creating sludge or oil to be separated from the aqueous component.
In the preferred form, a floating skimmer is placed in the user's machine sump and this is able to transport oil and contaminant-laden fluid to the treating elements. The remainder of the elements making up the system are preferably drums or transport vessels, together with hoses, manifolds, vacuum reliefs and other components. The servicing of the apparatus is carried out by a contractor who specializes in removing sludge and/or oil from the premises.
In the preferred form, the containers are removable and replaceable, and the components which are used in processing the fluids are reusable.
In one embodiment, the system contains a floating contaminant removal device, termed a “skimmer”, which has an inlet lying just beneath the surface of the liquid. In another embodiment, there is a dip tube or pick up which is dispensed in the body of the washing fluid bath itself. The liquid itself is continuously recirculated by means of a positive displacement pump and passes through one or more drums. The sludge may collect at the bottom of the drum, and the oils and other lighter-than-water contaminants are picked up from the top surface of the washing fluid in this embodiment by a floating skimmer and directed via suitable tubing through an oil trap, and finally, through a positive displacement pump before being returned in a substantially free of non-emulsified oil condition to the machine bath or other source of liquid. The oil trap, where present, removes tramp oil, floating solids, and other non-emulsified, lighter-than-water impurities, and in some cases, heavier than water contaminants which are trapped or otherwise contained in the oil or emulsified phases.
The system is designed to clean and maintain a variety of liquid systems which primarily use water, but also contain, in most cases in emulsion form, a lubricant for the machine, and various surface active gents which maintain the oil-water emulsion and prevent corrosion. There may be other components whose identity will vary somewhat with the application and the details of whose composition is not particularly relevant to the present invention.
An advantage of one form of the present invention is that it gives an outside contractor or supplier the ability periodically to service the apparatus without disturbing the principal machine, or compromising its operation. Thus, service may be performed by removing the sludge or oil from the trap or separator. This is accomplished merely by disconnecting the electrical power supply to the pump and disconnecting the fluid conduits leading to the various sludge or oil traps. In this way, the customer's principal machine need undergo no significant down time, or no down time at all. Most or all of the maintenance can be performed without stopping the principal machine.
The skimmer and the hose connecting it to the remainder of the apparatus may be simply serviced or replaced. This is because the skimmer preferably has no moving parts and preferably only one adjustable part. The height of the inlet may be adjusted simply by turning the threaded insert to raise or lower the skimmer inlet and thus to adjust the skim gap.
The sludge trap when operated without an oil trap preferably consists of a drum of the type used to transport liquids, namely, a 16-, 30-, or 55-gallon drum. The inlet at the source lies on or near the bottom of the customer sump in one embodiment. The hose leads to the sludge trap and the inlet to the drum is a fraction of the drum depth. The outlet connects to a fitting with a vacuum relief port. The liquid is advanced by a positive displacement pump, and the outlet of the pump connects with the customer sump to return the sludge-free fluid to the sump.
The construction of an oil trap according to the invention is such that a somewhat non-emulsified oil-water mixture enters the trap at a manifold and the liquid phase is directed downwardly well past the vertical middle of the trap. As the oil coalesces, it floats to the top and forms several layers. An air layer is at the top, an oil layer is next, then an emulsified oil-and-water layer, and finally, a lowermost water layer is formed. Accordingly, the water phase lies adjacent the bottom of the oil trap housing. The return tube extends toward the bottom of the vessel and has a connection at its upper end to the positive displacement pump; it is also in communication with the air in the air-tight manifold. The oil accumulates below a bleed hole in the manifold portion of the oil trap. The water passes from near the bottom to the return tube and hence is substantially oil-free. A strainer screen and a filter may be introduced between the trap and pump to protect the positive displacement pump from harmful impurities or components on this portion of the apparatus.
The positive displacement pump is preferably a bellows-, oscillating-, or diaphragm-type pump which functions at various flow rates but efficiencies are determined by the size of the drum used. A bellows-, oscillating-, or diaphragm-type pump is selected because of its self-priming capability. Preferably, the rate of the flow of the oil pump is selected so as to allow an appropriate residence time for oil and water separation within the oil trap. Additionally, a positive displacement pump provides low shear forces.
Another embodiment uses two identical oil trap drums cascaded so as to empty a more clear fluid from the first to the second. The two drums each include a manifold with an inlet, an outlet and a bleed opening, and the second one includes a vacuum break. Only one positive displacement pump is used, preferably just past the outlet of the second drum.
Still another embodiment cascades the sludge trap with an oil trap, with the oil trap having the bleed opening and the vacuum relief as well as the same positive displacement pump. This arrangement may have a skimmer or a bottom pick up, or both. Other arrangements may be found suitable.
The vacuum opening on the manifold may permit vacuum to be broken so as to protect the pump from becoming clogged or especially, collapsing one or more drums in operation.
In view of the failure of the prior art to provide a simple, integrated cost-effective system for liquids, including sludge and oil separators, that uses transport vessels as a part thereof, it is an object of the present invention to provide such an integrated or independent oil and/or sludge trap system.
It is another object of the invention to provide a sludge trap system, which, except for the pick up and discharge elements, lies entirely outside the apparatus with which it is used, and hence is functionally independent of such apparatus.
Yet another ob
Porter Brian E.
Shortreed William J.
FitzGibbon James T.
Lithgow Thomas M.
Safety-Kleen Systems, Inc.
Vedder Price Kaufman & Kammholz
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