Liquid purification or separation – Processes – Ion exchange or selective sorption
Reexamination Certificate
1999-07-13
2001-05-22
Simmons, David A. (Department: 1724)
Liquid purification or separation
Processes
Ion exchange or selective sorption
C210S746000, C210S112000, C210S170050
Reexamination Certificate
active
06235201
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to an apparatus and method for removing oil, hydrocarbons and other organic materials from water, particularly industrial waste waters, ship bilge pump waters, and rainwater collected on offshore oil drilling and production platforms, by adsorption with an oil adsorbent, while electronically monitoring the adsorbent with an embedded probe to determine when the adsorbent needs replacement. More particularly, the present invention is directed to an apparatus and method that includes relatively crude, gravity separation of oil from the water and then contacting the separated water, containing a small amount of hydrocarbons, such as oil and grease, with an organophilic clay to purify the water. During adsorption of the hydrocarbons, the adsorbent is monitored, by the probe to determine when the adsorbant is saturated and should be replaced or regenerated.
BACKGROUND OF THE INVENTION AND PRIOR ART
Offshore drilling and production platforms used for recovering oil from subterranean structure disposed beneath ocean water includes a number of structural support legs for supporting a plurality of work deck areas at substantial heights above the water level, e.g., disposed about 40 to about 100
+
feet above sea level. During the recovery of oil at one or more of these work deck areas, oil, grease and other hydrocarbons are unavoidably spilled onto the deck area(s) and it is not permissible to discard these hydrocarbons into the ocean water. Such work deck areas or platform surfaces are constructed to be fluid-impermeable in order to contain the spilled hydrocarbons on the work deck areas. These hydrocarbons, such as recovered oil, grease, surfactants and other organic contaminants, are directed from the work deck or platform areas, either by water washing or rain water, into a sump pump container or sump tank where the water and oil separate by gravity such that the water can be removed from a lower portion of the sump tank, for conveyance back to the ocean, and the oil can be pumped from an upper portion of the sump tank into an oil recovery container so that the oil is not returned to the ocean.
These contained deck areas on offshore structures collect a significant amount of water during periods of high rainfall. The rain water and entrained hydrocarbons, particularly recovered oil, grease and surfactants, are conveyed to the sump tank or collection tank through a gravity drain system from each of the work deck areas. These sump tanks rely on retention time as the primary oil/water separation mechanism in order to skim the lighter density hydrocarbons from a top of the sump tank so that the water can be returned to the ocean.
The sump tanks presently used on offshore platforms suffer from a number of major drawbacks which result in significant amounts of hydrocarbons, particularly oil, paraffins, grease, and refined hydrocarbons being returned to the ocean causing significant ecological contamination. One major drawback of the presently used sump tanks is that they are designed for a maximum of about three inches of rainwater per hour. It has been found that it is not uncommon to experience eight to ten inches of rainfall per hour in areas such as the Gulf of Mexico. Another major drawback of the sump tanks presently used on offshore drilling platforms is that a tank containing a layer of oil disposed above a layer of water will lose the water by evaporation over an extended dry period and the oil layer, as a result, will coat the inside surfaces of the sump tank such that water generated from even a modest rain shower, after this drying period, carries the oil through a water leg or drain portion of the sump tank as the water initially washes lower inner surfaces of the sump tank, thereby carrying the coated oil to the ocean.
In accordance with one embodiment of the present invention, there is provided an apparatus and method for treating an organic compound-containing waste water with a contained volume of an organophilic clay, the organophilic clay degrading with time due to continued adsorbance of the organic compound(s) from the waste water. The contained volume of organophilic clay includes an electrical probe disposed in contact with the organophilic clay for monitoring an electrical property of the waste water being treated, preferably monitoring the electrical conductance or electrical resistance of the waste water contacting the organophilic clay and the electrical probe, to obtain a visual or audible signal when it is time to regenerate or replace the organophilic clay (before the organophilic clay has adsorbed so much organic material that its capacity for further adsorbance of organics is insufficient to provide effluent water of sufficient purity).
In accordance with another embodiment of the present invention, the above-described drawbacks of a sump tank system for separation of water from oils and other hydrocarbons have been eliminated by the apparatus and method of the present invention wherein the sump tank water is conveyed for contact with an organophilic clay for final separation of hydrocarbons such as oil and paraffins from the water collected on work deck areas of an offshore drilling platform, while the organophilic clay is monitored so that it can be replaced before it becomes ineffective.
SUMMARY OF THE INVENTION
In brief, the present invention is directed to apparatus for monitoring adsorbance capacity of an organophilic clay by monitoring, continuously or periodically, an electrical property of the liquid being treated by the organophilic clay, particularly the electrical conductance or electrical resistance of the liquid being treated. The liquid being treated by the organophilic clay for removal of hydrocarbons therefrom can be an industrial waste water, ship bilge pump water, or, in a preferred embodiment, sump tank water collected on offshore drilling platforms (hereinafter collectively referred to as “waste water”). The organophilic clay is electronically monitored to provide a recognizable audible or visual signal, preferably an alarm, to indicate when the organophilic clay should be regenerated or replaced.
Accordingly, one aspect of the present invention is to provide a method of monitoring the changing adsorbance capacity of a contained volume of organophilic clay that is being used to treat an organic compound-containing waste water for removal of organic compounds therefrom such that a visible or audible signal is provided as an indication of when to regenerate or replace the organophilic clay.
Another aspect of the present invention is to provide a new and improved method and apparatus for complete separation of oil from water admixed on an offshore oil well drilling platform so that the separated water can be returned to the ocean without ocean contamination, with an oil adsorbent, such as an organophilic clay, while monitoring the oil adsorbent for oil saturation.
Another aspect of the present invention is to provide a new and improved method and apparatus for separation of oil and water including a first gravity separation step that provides for separation of water and oil by settling to provide layering of the water in a layer below an oil layer and then draining the lower water layer from the upper oil layer, and thereafter directing at least a portion of the separated water layer through a vessel containing an organophilic clay for contact with the organophilic clay for removal (adsorption) of remaining hydrocarbons entrained with the drained water layer, while electronically monitoring the oil adsorbent for oil saturation, such as by installing an electrical conductivity sensor within the oil adsorbent, such that a measurement of electrical conductivity of the hydrocarbon-contaminated water being treated indicates the extent of adsorption capacity remaining in the oil adsorbent.
Another aspect of the present invention is to provide a new and improved method and apparatus for separation of oil and water including a first gravity separation step that provides for separation
Berger Michael A.
Darlington, Jr. Jerald W.
Johnson Michael R.
Smith Jeffrey J.
Amcol International Corporation
Lawrence Frank M.
Marshall O'Toole Gerstein Murray & Borun
Simmons David A.
LandOfFree
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