Liquid purification or separation – Processes – Including controlling process in response to a sensed condition
Reexamination Certificate
1998-07-21
2001-05-29
Walker, W. L. (Department: 1723)
Liquid purification or separation
Processes
Including controlling process in response to a sensed condition
C210S740000, C210S744000, C210S800000, C210S801000, C210S803000
Reexamination Certificate
active
06238572
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method and apparatus for separating two immiscible liquids, for example, kitchen effluent contains a mixture of grease, water and solids.
Kitchen effluent generated during food processing has conventionally been collected in a grease trap separator, which is commonly a rectangular tank made of pre-cast concrete, buried below grade. In the separator, the grease, being of a lower density than the water, rises to the top, forming a separate grease mat layer. Periodically, the grease is removed from the trap, normally with a vacuum pump. The grease may then be disposed of in a landfill or sold to rendering companies for conversion into useful products.
Processing of the grease into useful products is obviously preferred to dumping of the grease into a landfill, which also may not be possible due to the increased environmental regulations. Processors, however, are not always willing to accept grease if it includes a significant percentage of water, i.e., more than fifteen percent (15%), because of the increased difficulty in processing. Moreover, the prolonged contact of water with the grease tends to make the grease rancid as a result of the breakdown of lipids into shorter chain fatty acids, decreasing the value of the grease.
The prior art discloses various methods and apparatus for separating two immiscible liquids, and also discloses various methods and apparatus for removing one liquid from contact with the other after separation of liquids into two layers in a separator. For example, in some cases, the lighter liquid is discharged by gravity from the separator through an upper pipe and the heavier liquid is discharged from the separator through a lower pipe. Generally, the methods and apparatus relate to the separation of grease or oil from water.
U.S. Pat. No. 2,747,736 to Mobley describes a device for removing grease from wastewater in a separator, in which grease which floats to the top of the separator is removed by hydrostatic forces. The grease is then stored at a collecting and storage point remote from the separator.
U.S. Pat. No. 5,236,585 to Sink describes an apparatus comprised of a separator in which oil and water are separated. The oil, which floats to the top of the water, flows under gravity to a second separator, where remaining oil is removed, e.g., by filtration. Water is removed from the bottom of the first separator.
Other patents show similar devices. U.S. Pat. No. 4,915,823 to Hall, describes a device for separating oil from water in bilge discharges. After separation, the oil and water are removed through separate discharge pipes. U.S. Pat. No. 4,119,541 to Makaya, discloses a similar arrangement for cleaning up oil spills by separating oil from seawater. U.S. Pat. No. 4,400,274 to Protos, describes a gravity separator in which solids are removed prior to separation of the grease and water. Those systems often suffer the problem of incomplete removal of grease from the water, leading to waste of recyclable grease, and perhaps more importantly, the need to treat the water more thoroughly because of the residual grease contaminants.
The kinds of apparatus disclosed in the prior art, however, are not readily adaptable for use with the thousands of conventional grease traps that currently exist. Since these traps are generally comprised of a concrete storage tank buried several feet below ground level, i.e., grade, which has a pair of generally cylindrical access ports fitted with manhole covers, removal or structural modification is difficult. An apparatus which would permit removal of grease from water with great efficiency in conventional grease traps would be of substantial commercial utility.
Further, there is a need in the art for a new apparatus for separation of oil/grease from wastewater which is simple in design so that service is not often needed, yet capable of being done in the field by simple replacement of easily replaceable parts.
SUMMARY OF THE INVENTION
The current invention is useful in retrofitting existing separation systems, such as grease traps, many of which are located below grade. After modification of the grease trap with the present invention, the first liquid (grease) can be periodically and automatically removed and transported to a remote location.
While the invention is described in terms of the separation of grease from water, it will be apparent that the apparatus and method described herein are generally useful in the separation of any immiscible liquids.
The apparatus includes a containment vessel, an influent channel having an intake end and a discharge end disposed into a central region of the vessel, an effluent channel disposed in the vessel having an intake end in a lower portion of the vessel and a discharge end. A plate in a lower portion of the vessel has a downward slope from a central location toward the periphery of the vessel and is mounted downstream of flow from the discharge end of the influent channel. Influent liquid can be introduced into the vessel through the influent channel for discharge centrally into the vessel to permit radially outward movement of the influent to slow the influent and provide residence time for gravitational separation of lighter immiscible liquids from the main liquid flow.
The apparatus may include a transfer tube with an intake end and a discharging end with the intake end located in an upper portion of the vessel. It may also include a sensor for sensing immiscible liquids within an upper portion of the vessel and a pump actuable upon the sensor sensing immiscible liquids to pump from the vessel.
The apparatus may have a vertically extending suction conduit having an intake end and a discharge end, whereby the intake end can be inserted through the center portion of the vessel to permit the suction of heavier-than-water solids from the bottom portion of the vessel.
In one preferred embodiment the influent end is inserted from the upper portion of the vessel so the influent flow is discharged vertically downward. Thereafter, the influent is collected on an upwardly curved deflection plate mounted below and aligned with the discharge end of the influent channel. The downward slope plate is in a lower portion of the vessel than the deflection plate to provide an overhang from an outer peripheral portion of the deflection plate above an inner central portion of the downward slope plate.
In another embodiment, the influent end is inserted from the bottom portion of the containment vessel so the influent flow is discharged vertically upward. In this embodiment, a downwardly curved deflection plate is mounted above and aligned with the discharge end of the influent channel. The downward slope plate is mounted to the discharge end of the influent channel so the downward slope plate is in a lower portion of the vessel from the deflection plate. Further, one portion has a gap between the discharge end of the influent channel and the downward slope plate.
An embodiment of the vessel may be vertically extending with a generally rounded bottom, formed of roto-formed plastic and having a cover. Such a cover may have a flat top surface, a radial inwardly upwardly slanted bottom surface and an opening through the middle. Further, the channels, preferably, are made of vacuum formed plastic.
In the preferred embodiment, a conical plate is used to define the bottom of the vessel, the influent channel is disposed vertically along one side of the vessel, the effluent channel is disposed vertically along another side of the vessel such that the central peripheral portion of the channels is mounted to the outer peripheral portion of the conical plate.
The apparatus may have a gray water conduit, having an intake end from a remote location and a discharge end disposed into an upstream location of the discharge end of the influent channel. It may also have a transfer tube, with an intake end located in the upper portion of the vessel and a discharge end in a remote location for recovery of the separated grease. Additionally it may have a verti
Clearline Systems, Inc.
Fleming Michael A.
Rhodes & Mason PLLC
Walker W. L.
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