Note: Descriptions are shown in the official language in which they were submitted.
CA 02560344 2001-11-05
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METHOD P.ND APPAF,ATUS FOR REMOVING OIL FROM WATER
INCLUDING MONITORING OF ADSORBENT SATURATION
This is a divisional application of Canadian Patent Application
No. 2,422,074 filed on November 5, 2001.
FIELD OF THE TNVENTION
The present invention is directed to an apparatus and method fox
removing oil, hydrocarbons and other organic materials from water,
particularly
industrial waste waters, ship bilge pump waters, produced water and rainwater
collected on offshore oil drilling and production platforms, by adsorption
~~ith an
oil adsorbent, while electronically monitoring the adsorbent with an embedded
probe to d~tei~ine whenthe adsorbentneeds replacement. More particularly, the
present invention is directed to an apparatus and method that includes
relatively
crude, ;cavity separation of oil from the water and then contacting the
separated
1.5 water, oontainin.g a small amolmt of hydrocarbons, such as oil and grease,
with
an orgunophilic clayto purify the water. During adsorption of the
hydrocarbons,
the adsorbent is monitored, by the probe, to determine when the absorbent is
saturated and should be replaced or regenerated. Further, the present
invention
is directed tovaards an improved vessel for housing a plurality of cartridges
of the
' .
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organophilic clay with a removable header for directing filtered water out of
the
vessel.
BACKGROUND OF THE INVENTION AND PRIOR ART
Offshore drilling and production platforms used for recovering oil
from subterranean formations 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 from 40 to 100 or
more
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 areas) and it is notpermissible 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 rainwater, into a sump pump container or sump tank where the water
and oil separate by gravity so 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.
2 o These contained deck areas on offshore structures collect a
significant amount of water during periods of high rainfall. The rainwater 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
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primary oiUwater 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 maj or 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.
This phenomena is known in the art as sheering. As a result of the sump tank
sheering, 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
oil to the ocean.
2 0 Another water treatment problem associated with offshore oil
platforms is the treatment of the aqueous solutions used in acid fracturing
processes. Specifically, acidic solutions are commonly pumped down under
pressure to cause fractures in the oil producing regions of the formation. As
these
acidic solutions are returned to the surface, they are often contaminated with
oil
CA 02560344 2001-11-05
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or hydrocarbons. As discussed above with respect to
rainwater, the hydrocarbons must be removed from the
solutions before the water is returned to the ocean.
Another problem associated with all auxiliary
equipment used on oil platforms is the need for equipment to
be designed in a space efficient manner. Specifically,
auxiliary equipment, including water treatment equipment,
must be designed in as space efficient manner as possible
because horizontal square footage on an oil platform is
scarce. Therefore, there is a need for water treatment
equipment that can treat water at a fast rate, but which is
also space efficient.
SUN~2ARY OF THE INVENTION
According to one aspect of the present invention,
there is provided a filter for separating hydrocarbon
contaminant from a liquid containing water and said
hydrocarbon contaminant, the filter comprising: an outer
cylindrical permeable cover having a top edge and a bottom
edge; an inner cylindrical permeable tube having a top edge
and a bottom edge; an annular bottom connecting the bottom
edge of the outer cover to the bottom edge of the inner
tube; an annular top connecting the top edge of the outer
cover to the top edge of the inner tube; a probe connected
to one of the annular top or the annular bottom at a middle
position between the inner tube and the outer cover, the
probe comprising two spaced apart elements, each element
being connected to a wire lead, each wire lead being
connected to a control panel; and wherein the outer cover
comprises organophilic clay being disposed in a space
defined by the inner tube, the annular top and the annular
bottom, the organophilic clay surrounding the probe.
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In some embodiments the elements each comprise a
metallic hollow circle.
In some embodiments the elements are made from
stainless steel.
In some embodiments the elements are made from
Hasteloy/Incanel.
In some embodiments the elements are aligned
parallel to a radius defined by a common axis of the outer
cover and the inner tube and which extends between the two
elements.
According to another aspect of the present
invention, there is provided an apparatus for separating
hydrocarbons from a liquid containing water and
hydrocarbons, the apparatus comprising: a vessel connected
15~ to an inlet and an outlet; the inlet for conveying the
hydrocarbons and water into the vessel; the vessel further
Comprising at least one permeable conduit, the conduit
passing through at least one cylindrical cartridge; the at
least one cylindrical cartridge comprising a filter
according to the present invention, wherein the liquid flows
radially inwardly through the outer cover, through the
organophilic clay and through the inner tube before flowing
into the conduit, the organophilic clay providing intimate
contact with the liquid and adsorption of the hydrocarbon
contaminant; the conduit being connected to a header and
extending upward from the header, the header being disposed
inside the vessel and being detachably connected to the
outlet.
According to still another aspect of the present
invention, there is provided a method of manufacturing an
apparatus for separating hydrocarbons from a liquid
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containing water and hydrocarbons, the method comprising:
providing a hollow cylinder having an open top end, an open
bottom end and an inside surface; welding a bottom structure
to the bottom end of the cylinder to enclose the bottom end
of the cylinder, the bottom structure comprising an inside
surface and a drain outlet with a valve disposed exterior to
the bottom structure for opening and closing the drain
outlet, the bottom structure further comprising a treated
water outlet, the treated water outlet comprising an inner
end disposed inside the bottom structure; coating the inside
surface of the bottom structure and the inside surface of
the cylinder with a protective coating; connecting a header
to the inner end of the treated water outlet; connecting at
least one permeable conduit to the header; and placing at
least one cartridge, comprising a filter according to the
present invention, on one of the conduits, the permeable
conduit extending through the inner tube, the organophilic
clay providing intimate contact with the liquid and
adsorption of the hydrocarbon; attaching a removable top
structure to the top end of the cylinder.
According to yet another aspect of the present
invention, there is provided a method of separating water
from a liquid comprising a combination of water and a
hydrocarbon contaminant comprising: flowing the liquid into
a filtration vessel comprising an outlet, a header connected
to the outlet, and at least one permeable conduit connected
to the header, the conduit passing through a plurality of
cylindrical cartridges, each cylindrical cartridge
comprising a filter according to the present invention, the
organophilic clay providing intimate contact with the liquid
and adsorption of the hydrocarbon contaminant; providing a
pressure within the filtration vessel of greater than
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atmospheric; and flowing the separated water through the
conduit, through the header and out through the outlet.
In accordance with one embodiment of the present
invention, an improved apparatus is provided for separating
hydrocarbons from a liquid containing water and
hydrocarbons. The apparatus includes an improved vessel
design. The vessel includes an inlet for conveying
contaminated water into the vessel and an outlet for
transporting treated water out of the vessel. A removable
header is connected to the outlet and housed within the
vessel. Permeable conduits are connected to the header and
extend upward therefrom. Cartridges containing organophilic
media for adsorbing hydrocarbons are then stacked on the
permeable conduits. Each cartridge includes a permeable
outer cover, a permeable inner tube with the organophilic
media disposed therebetween. A pressure drop is provided
between the vessel inlet and the vessel outlet, and
therefore between the vessel inlet and the permeable
conduits. As a result, the contaminated liquid flows
radially inwardly through the outer cover of the cartridges,
through the media and through the inner tube of the
cartridge before
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flowing into the conduit. Intimate contact between the media and the
contaminated liquid results in adsorption of the hydrocarbon contaminents on
the
media. The header is detachably connected to the treated liquid outlet thereby
facilitating removal of the header for replacement or servicing. Accumulated
solids, which do not pass through the cartridges, are conveniently collected
at the
bottom of the vessel and can be flushed out through a drain valve.
In accordance with another aspect of the present invention, an
improved method of manufacturing such a vessel is provided. A bottom structure
is welded to an open bottom end of a hollow cylinder. The bottom structure
1 o includes a drain outlet with a valve disposed exterior to the bottom
structure for
opening and closing the drain outlet. The bottom structure also includes a
treated
liquid outlet with an inner end disposed inside the bottom structure. The
inside
surfaces of the bottom structure and the cylinder are coated with a protective
coating to resist corrosion in the presence of salt water and very acidic or
basic
solutions. A header is connected to the inner end of the liquid outlet and
contained within the bottom structure of the vessel. Pen~eable conduits are
then
connected to the header and extend upward through the cylindrical section of
the
vessel. Cartridges, like those described above, are placed singly or are
stacked
one on top of another with the permeable conduits extending through the inner
2 o tubes of the cylindrical cartridges. The improved method enables the weld
connecting the bottom structure to the bottom end of the cylinder to be easily
coated with the protective coating. Further, because a header is employed, the
bottom of the vessel may be used to accumulate solids that do not pass through
the cartridges and, because the bottom of the vessel is not needed to collect
2 5 treated water, a greater portion of the height of the vessel is utilized
for cartridges
thereby increasing the treatment capacity of each vessel.
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In accordance with another embodiment of the present invention,
an apparatus and method are provided fox treating or polishing an organic
compound-containing waste water with a contained volume of organophilic
media wherein the organophilic media degrades with time due to continued
adsorbance of the organic compounds) from the waste water onto the media.
In accordance with a preferred embodiment, the preferred media
is an organophiIic clay and the contained volume of organophiIic clay includes
a probe disposed within the clay-containing vessel, in contact with the
organophilic clay, for monitoring an electrical property of the organophilic
clay,
preferably by monitoring the electrical conductance or electrical resistance
of 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). It is anticipated that radio frequency or ultrasonic
monitoring ,
of the waste water being treated will serve as suitable substitutes for
electrical
conductance or resistance measurements.
In accordance with another embodiment of the present invention,
the above-described drawbacks of a sump tank system for separation of water
2 0 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 media for final separation of hydrocarbons such
as
oil and paraffins from the water collected on work deck areas of an offshore
drilling platform, preferably while the organophilic media is monitored so
that it
2 5 can be replaced before it becomes ineffective.
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_ 7 _
In brief, one aspect of the present invention is an improved vessel
design for accommodating organophilic cartridges in a more space e~cient
manner. Specifically, the improved vessel design includes an inlet and an
outlet.
A header is connected to the outlet and disposed inside the vessel near the
bottom
thereof. The header is connected to one or more permeable conduits that extend
upward therefrom. Organophilic media cartridges can then be stacked on the
permeable conduits. A pressure drop between the inlet and the outlet causes
the
contaminated liquid to flow radially inwardly through the permeable outer
covers
of the cartridges, through the media, through the permeable inner tubes of the
1 o cartridges and into the permeable conduits. Because intimate contact
between~the
media and liquid results in adsorption of the hydrocarbon contaminate on the
media, treated water passes through the inner tubes of the cartridges and into
the
permeable conduits. The treated water then flows down through the conduits,
through the header and out of the vessel through the outlet.
Another aspect of the present invention is to provide a removable
header connected to the treated fluid outlet and disposed inside the vessel.
By
enabling the header to be removable, the header may be removed andlor replaced
when necessary. The employment of a header avoids the use of the bottom of the
vessel for collecting treated fluid and thereby enables a greater proportion
of the
2 o height of the vessel to be used for stacked filter cartridges thereby
increasing the
capacity of each vessel while not increasing the horizontal footprint of the
vessel.
Another aspect of the present invention is directed toward an
improved method for manufacturing vessels for accommodating organophilic
cartridges for treating hydrocarbon-contaminated water.
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_ g _
Another aspect of the present invention is directed toward a
method of manufacturing an apparatus for separating hydrocarbons from a
water/hydrocarbon mixture. The manufacturing method includes the steps of
providing a hollow cylinder having an open top end, an open bottom end and an
inside surface, welding a bottom structure to the bottom end of the cylinder
to
enclose the bottom end of the cylinder. The bottom structure includes an
inside
surface with a drain outlet with a valve disposed exterior to the bottom
structure
for opening and closing the drain outlet. The bottom structure also includes a
treated water outlet which has an inner end disposed inside the bottom
structure.
1 o The method further includes the steps of coating the inside surface of the
bottom
structure and the inside surface of the cylinder with a protective coating,
connecting a header to the inner end of the treated water outlet, connecting
at
least one permeable conduit to the header, and placing at least one cartridge
on
the conduit. The cartridge includes a permeable outer cover and a permeable
inner tube through which the conduit extends. The cartridge contains an
organophilic media between the outer cover and the inner tube. Intimate
contact
between the media and liquid results in adsorption of the hydrocarbon in the
liquid on the media. Finally, the method includes the steps of attaching a
removable top structure on the top end of the cylinder.
2 o Yet another aspect of the present invention is directed toward a
method of separating water from a liquid that comprises a combination of water
and a hydrocarbon contaminate. The separation method includes the step of
flowing the liquid into a vessel that includes an outlet, a header connected
to the
outlet and at /east one permeable conduit connected to the header. The conduit
2 5 passes through a plurality of cylindrical cartridges. Each cartridge
includes a
permeable outer cover, a permeable inner tube and contains an organophilic
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_ g _
media between the outer cover and inner tube. The method further includes the
step of providing a negative pressure gradient between a portion of the vessel
exterior to the cartridges and the inside of the permeable conduit thereby
causing
the liquid to flow radially inwardly through the outer cover of each
cartridge,
through the media and through the inner tube before flowing into the conduit
Another aspect of the present invention is directed to an apparatus
for monitoring adsorbance capacity of an organophilic media by monitoring,
continuously or periodically, a property of the liquid being treated by the
organophilic media, particularlythe electrical conductance or electrical
resistance
of the liquid being treated. The liquid being treated by the organophilic
media for
removal of hydrocarbons therefrom can be an industrial waste water, ship bilge
pump water, produced water, or, in a preferred embodiment, sump tank water .
collected on offshore drilling platforms (hereinafter collectively referred to
as
"waste water"). The organophilic media preferably is electronically monitored
to provide a recognizable audible or visual signal, preferably an alarm, to
indicate
when the organophilic media should be regenerated or replaced.
Another aspect of the present invention is to provide an improved
probe for monitoring the organophilic clay when organophilic clay is used as
the
organophilic media A probe in accordance with the preferred embodiment of the
2 0 present invention is disposed within one of the cartridges and includes
two spaced
apart elements for monitoring a property of the liquid flowing through the
clay.
The elements preferably are aligned transverselyto the radially inward flow of
the
liquid through the clay. A convenient property to measure is either the
conductivity or resistivity of the fluid by applying a voltage across the two
spaced
2 5 apart elements. An increase in the resistivity or a decrease in the
conductivity of
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the organophilic clay will serve as an indication that the organophilic clay
contains hydrocarbon and therefore the organophilic clay needs to be
regenerated
or replaced. The probe should be placed within the canister and adjacent to
the
inner tube of the canister as saturation of the organophilic clay will begin
from
the outside or adjacent to the permeable cover of the canister and proceed
inward
towards the inner tube.
Another aspect of the present invention is to provide an improved
organophilic media canister'for separating hydrocarbon contaminate from water
that provides an indication as to when the organophilic media has become
saturated with hydrocarbon and therefore needs to be replaced or regenerated.
The filter canister of the present invention includes an outer cylindrical
permeable
cover, an inner cylindrical permeable tube, an annular bottom connecting
bottom
edges of the outer cover to the inner cube, an annular top connecting top
edges of
the outer cover to the inner tube and, in a preferred embodiment, includes a
probe
connected between the inner tube and the outer cover, preferably connected to
one of the annular top or annular bottom at a middle position. The probe
includes
two spaced apart elements. The spaced apart elements are each connected to a
wire lead. Each wire lead is connected to a control panel. The elements
preferably are aligned transversely to a radial flow from the outer cover .to
the
2 0 inner tube or, in other words, transversely to a radius defined by a
common axis
of the outer cover and the inner tube and which extends between the two spaced
apart elements. Finally, the filter cartridge includes organophilic media
disposed
in the space defined by the inner tube, the outer cover, the annular top and
the
annular bottom. The organophilic media surrounds the probe and comes in
2 5 intimate contact with liquid flowing through the canister.
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Another aspect of the present invention is to provide a method of
monitoring the changing adsorbance capacity of a contained volume of
organophiIic media 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 media.
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
1 o be returned to the ocean without ocean contamination, with an oil
adsorbent, such
as an organophilic media, 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 Iayer below an oil Iayer 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 oil
adsorbent
for contact with the oil adsorbent for removal (adsorption) of remaining
hydrocarbons entrained with the drained water layer, while electronically
2 0 monitoring the oiI 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 oil adsorbent indicates the extent of
adsorption.
capacity remaining in the oil adsorbent.
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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 aid then draining
the
lower water' Dyer from the upper oil layer, and thereafter directing the
separated
water layer through a vessel containing an organophilic media for pressurized
contact with the organophilic media, at a pressure of about atmospheric,
preferably at least 10 psig above atmospheric, for removal (adsorption) of
remaining hydrocarbons entrained with the drained water layer.
1 o The data of Table I show that, at atmospheric pressure and up to
Iess than 10 psig water pressure entering the organophilic media-containing
vessel, the effluent is cloudy and contains detectable levels of oil:
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TABLE I
EFFECT OF PRESSURE ON OIL ADSORPTION
BY ORGANOPHILIC CLAY
Pressure Influent Oil Color of
Concentration Concentration Effluent
and Color via EPA
Method 413.1
Atmospheric 100 ppm, dark 27 ppm Cloudy, dark
1 psig 100 ppm, dark 26 ppm Cloudy, dark.
2 psig 100 ppm, dark 24 ppm ~ ' Cloudy, dark
3 psig 100 ppm, dark 22 ppm Cloudy, dark
4 psig 100 ppm, dark 21 ppm Cloudy, light v'
S psig 100 ppm, dark 20 ppm Cloudy, light
10 prig 100 ppm, dark 12 ppm Clear
1 S psig 100 ppm, dark 8 ppm ' Clear
prig 100 ppm, dark 4 ppm - , Clear
psig 100 ppm, dark 1 ppm Clear
15 30 prig ~ 100 ppm, dark~ 1 ppm Clear
psig 100 ppm; dark Non detect Clear
psig 100 ppm, dark Non detect Clear
4S psig 100 ppm, dark Non detect Clear
prig 100 ppm, dark Non detect Clear
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The above and other aspects and advantages of the present
invention will become more apparent from the following detailed description of
the preferred embodiment read in conjunction with the drawings.
BRIEF DESCRTPTIOl~ OF TFIE DRAWINGS
FIG. 1 is a side view of an offshore oil well drilling platform
generally showing the oil and water separating apparatus and method of the
present invention attached to a platform support structure with an alternative
placement of a sump tank;
FIG. 2 is a side view of one embodiment of an oil and water
1 o separating apparatus and method of the present invention;
FIG. 3 is a sectional view of an embodiment of a vessel containing
a plurality of organophilic media-containing cartridges for efficient contact
of
hydrocarbon-containing water with an organophilic media contained therein;
FIG. 4 is an elevational view of a preferred embodiment of a
vessel containing a plurality of organophilic media-containing cartridges for
efficient contact of hydrocarbon-containing water with organophilic media
contained within the cartridges;
FIG. 5 is a top plan view of the header of the vessel shown in FIG.
4 and openings within the header for receiving permeable conduits each of
which
2 o can extend through a stack of $lter cartridges as shown in FIGS. 3 and 4;
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FIG. 6 is a partially broken-away side view of an embodiment of
a sump water polishing unit of the present invention, containing multiple,
stacked
cartridges (FIGS. 3 and 4), wherein one of the cartridges is equipped with a
probe
for indicating when the cartridge becomes saturated, or nearly saturated, with
hydrocarbons, so that the sump water can be directed into another polishing
unit
while cartridges are replaced;
FIG. 7 is a sectional elevational view of a preferred embodiment
of a probe for placement within an organophilic media-containing filter
cartridge
which provides a signal indicating when the media of said cartridge is
sufficiently
1 o contaminated or saturated with hydrocarbon so as to need replacement or
regeneration;
FIG. 8 is a top plan view of the top cap of the probe shown in FIG.
7;
FIG. 9 is a bottom plan view of the bottom cap of the probe shown
in FIG. 7;
FIG..10 is an elevational view of one of the elements of the probe
shown in FIG. 7;
FIG. 11 is an elevational view of a preferred embodiment of an
organophilic media-containing cartridge shown i . FIGS. 3 and 4;
2 o FIG. I2 is a top plan view of the organophilic media-containing
cartridge shown in FIG. 11;
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FIG. 13 is a sectional view of an annular bottom plate of an
organophilic media-containing filter cartridge made in accordance with the
present invention; and
FIG. 14 is a partial side plan view of a filter canister illustrating
the position of a probe therein.
It should be understood that the drawings are not necessarily to
scale and that the embodiments are sometimes illustrated by graphic symbols,
phantom'lines, diagrammatic representations and fragmentary views. In certain
instances, details which are not necessary for an understanding' of the
present
1 o invention or which render other details difficult to perceive may have
been
omitted. It should be understood, of course, that the invention is not
necessarily
limited to the particular embodiments illustrated herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to the drawings, and initially to FIG. l, there is
shown an offshore drilling platform generally designated by reference numeral
10, including a work deck support structure 12 for supporting a plurality of
stacked work decks at a substantial height above an ocean water level 14. The
work decks commonly include a cellar deck 16 at a lowest work deck level, a
second deck 18 located directly above the cellar deck 16, a third deck 20
disposed
2 o directly above deck I 8, and a main deck 22 at an uppermost work deck
level. In
extant offshore drilling platforms, a sump tank 24 has been connected to the
drilling platform 10 at the cellar deck level 16 and rainwater, including
entrained
hydrocarbons, particularly oil, paraffins and surfactants have been directed
from
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all deck levels, which are contained so that rainwater and entrained
hydrocarbons
do not spill over to the ocean, to drain by gravity into the sump tank 24. It
has
been found that further separation of hydrocarbons from rainwater is required
for
effective elimination of ocean water contamination by providing a secondary
hydrocarbon recovery apparatus and method for organophilic media treatment of
the rainwater separated by gravity in the sump tank 24 or 24A.
In accordance with a preferred embodiment of the present
invention, it has been found that the apparatus and method of the present
invention function best when the sump tank 24A is disposed on or near a boat
landing deck level 26 (FIG.1) of the offshore drilling platform I 0. However,
the
sump tank can also be disposed at an upper level, in accordance with the
present
invention, as indicated by reference numeral 24 in FIG. 1.
In accordance with a preferred. embodiment of the present
invention, it has been found that the apparatus and method of the present
invention function best when the oil-contaminated water treated in the
organophilic media-containing vessel is pressurized above atmospheric
pressure,
preferably to at least about 1 Opsig, while in contact with the organophilic
media.
In accordance with an important feature of the present invention, when the
contaminated water is pressurized to at least 5 psig, preferably to at least
10 prig,
2 0 the effluent sent back to the ocean is clear (not cloudy) and has
surprisingly Iess
remaining oil as a result of pressurized contact of the oil-containing water
with
the organophilic media.
Pressurized contact of the oil-containing water with the
organophilic media can be accomplished in a number of ways. One method of
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_ 18
establishing pressurized contact of oil-contaminated water with the
organophilic
media, when used on an offshore drilling platform, is by placement of sump
tank
24A at the cellar deck level 16, and by securing the organophilic media-
containing cartridge 44 at or near the boat landing deck level 26 (such that
at least
a portion of the organophilic media-containing cartridge 4-4. is within about
10
feet of ocean level). Oil and other hydrocarbons collected on the production
decks 16, 18, 20 and 22 that may accumulate during dry weather on the inner
surfaces of the conduit 28 and inner surfaces of sump tank 24 can be separated
from the water that flows from the decks to the organophilic media-containing
l0 cartridge 44 for recovery and separation in accordance with the apparatus
and
method of the present invention.
Other expedients for establishing pressure within the organophilic
media-containing cartridge 44 include installing a valve 47 (FIG.2) , or 71
(FIG.
3) or other restrictions in the effluent conduit 48 (FIG.2) or 73 (F1G. 3).
Water and entrained hydrocarbons are conveyed via conduit 28
from the deck areas 16,18, 20 and 22 along the platform infrastructure or
support
leg 12 down to the sump tank 24 or 24A, preferably sump tank 24A, for
convenient servicing and/or organophilic media cartridge replacement. Although
placement of sump tank 24A. at this level has not been expedient with prior
art
2 0 sump tank gravity water/oil separation, it is now expedient to dispose the
water/oil separation apparatus of the present invention at or near the boat
landing
deck level 26 (such that a: least a portion of the s~,zmp tank 24A is within
about
10 feet of ocean level) since oil and other hydrocarbons collected on the
production decks 16, 18, 20 and 22 that may accumulate during dry weather on
2 5 the inner surfaces of the conduit 28 and inner surfaces of sump tank 24A
can be
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separated from the water that flows from the decla to the sump tank 24A for
recovery and separation in accordance with the apparatus and method of the
present invention.
Turning nowto FIG. 2, tbere is shown another embodiment of the
hydrocarbon separation apparatus of the present invention that includes a b
avifiy
separation sump tank 24A for gravity separation of a lower level of water ? 9
from
a floating layer of oil 30. The water 29 is conveyed through a water outlet 32
disposed near a bottom of the sump tank 24A through a water leg 34 in the
shape
of an inverted U. The water leg 34 achieves gravity flow of water through the
water leg 34 only when the level of water within the sump'tank 24A reaches
height h, above an uppermost or base portion 34A of water leg 34. The sump
tank 24A includes an inner, contained float valve housing 36 open at its top
38
for receiving oil from oil level 30 when the level of liquid within the sump
tank
24 reaches height h'. Float valve 40 is disposed within inner housing 36 and
is
connected to a pump (not shown) for pumping oil into an oiI recovery vessel
when a floating ball portion 41 of float valve 40 rises to a predetermined
level
within inner valve housing 36 as a result of oil entering inner vessel 36 when
the
liquid level h' is reached within sump tank 24A. While h and h' are shown to
be
appro~.imately equal, h may be smaller than h' in order to achieve water
removal
2 0 without oil pumping, as well known in the art.
In accordance with an important feature of the present invention,
a doumwardIy extending Ieg portion 42 of water Ieg 34 is operatively
interconnected to, and in fluid communication with, one or more sump water
polishing units 44 containing a volume of oil adsorbent, particularly an
organophilic media. The separated watez flows by gravity through water leg
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conduit 42 and is conveyed through conduit 42 into sump water polishing unit
44
containing organophilic media. The organophilic media within sump water
polishing unit 44 adsorbs the hydrocarbons, oil and other organic materials
entrained with the water flomng thl'Ol:lgh C017duii 42 for essentially
complete hydrocarbon removal (less than about I 0 parts per azillion,
preferably
less than about 1 part per million organics after organophilic media
treatment).
The treated water flows by gravity through water exit opening 46 in the sump
water polishing unit 44 and through e~:it conduit 48 back to the ocean water
14.
It will be noted that FIG. 2 is a simplified drawing of an actual
apparatus which, preferably, would include a plurality of vessels 44 connected
downstream of one or more sock filters (not shown). The vessels 44 would also
be connected upstream of one or more activated charcoal filters (not shown) or
other suitable filter as a foal polishing step before the water is returned to
the
ocean. Such sock filters and activated charcoal or carbon filters are well
known
to those skilled in the art.
As shown in FIGS. 3 and 6, the sump water polishing unit 44
includes an outer, fluid-impermeable housing 48 having a water inlet 42
interconnected through the housing 48 so that contamunated water enters the
polishing unit 44 and then enters the organophilic media-containing vessels or
2 0 cartridges 55, through a plurality of apertures 56. The organophilic media-
containing cartridge 55 is water-permeable by virtue of the water flow
apertures
56 that are sized sufficiently small such that organaphilic media granules do
not
pass therethrough. Water entering the polishing unit 44 through water inlet
conduit 42 and apertures S6 flows radially inwardly into longitudinal, axial,
2 5 central conduits 50, S l, 52, 53 and 54, each containing treated water-
receiving
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apertures 57 for receiving the organophilic media-treated water. Organophilic
media contained in cartridges SS adsorbs any oil and organics contained in the
water and the clean water exits through exit openings 59, 61, 63, 65 and 67 in
each stack of cartridges 55 and the clean water collectively exits the housing
48
through ehit conduit 69 and through valve 71 and then is returned to the ocean
via
outlet 73.
Turning to FIG. 4, another embodiment of a vessel 100 containing
stacks of cartridges, one of which is shown at 102. Each cartridge stack
includes
a plurality of annular cartridges 104 through which a porous conduit 106
extends.
1 o The porous conduit 106, instead of being connected to a porous tube sheet
111
as shown in FIG. 3, instead is connected to a header 108 which is disposed
within
a bottom section I 10 of the vessel 100.
Turning to FIG. 5, the header I08 is connected to a filtered water
outlet 112 which includes a flange 114 which is connected to the flange 116 of
the header 108 by a plurality of fasteners, such as bolts (not shown). The
header
is also supported within the vessel, or more specifically, within the bottom
structure 110 (see FIG. 4) of the vessel by a plurality of supports shown at
118.
The header 108 includes a plurality of openings 120, each of which receives a
permeable conduit 106 (see FIG. 4). In the embodiment illustrated in FIGS. 4
and
2 0 5, the header 108 is connected to 23 permeable conduits and therefore
supports
33 stacks of cartridges 104. By providing the header 108 within the bottom
structure 110 of the vessel 100, the permeable tube sheet I 1 I shown in FIG.
3 is
eliminated and the bottom section 110 of the vessel can be used to collect
accumulated solids, or solids which do not pass through the outer covers of
the
2 5 filter cartridges 104. A drain 122 is provided for purposes of flushing
out the
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22 -
accumulated solids which settle in the bottom structure 110 of the vessel 100.
In
contrast, as shown in FIG. 3, solids will accumulate on top of the tube sheet
111.
Thus, the solids must be removed from above the tube sheet 108 using one or
more nozzle openings shown at 109 in FIG. 3. As shown in FIG. 4, these
additional nozzle openings are not required in the vessel 100 because the
accumulated solids are easily flushed down the drain pipe I22.
Further, by utilizing the header 108 and eliminating the tube sheet
111, the interior space of the vessel 100 is more e~ciently utilized.
Specifically,
a greater proportion of the interior volume of the vessel 100 is available for
stacking cartridges 104. In contrast, the~design shown in FIG. ~3 requires the
cartridges to be stacked on top of the tube sheet 11 I and the filtered water
to be
collected in the bottom area 103 before flowing out through the exit conduit
69.
Still further, the construction of the vessel 100 facilitates both the
assembly and the painting or the application of protective coating to the
inside of
the vessel 100. Specifically, the bottom structure 110 is equipped with the
drain
122 and the filtered water outlet 112. The bottom structure I IO can then be
welded to the cylindrical portion I24 of the vessel 100. At this point, the
inside
surfaces of the cylindrical section 124 and the bottom structure I 10 can be
painted with a protective coating to prevent rust and con:osion caused by salt
2 0 water and/or acidic water. The welding seam shown at 126 can be easily
coated
with the protective coating.
In contrast, the vessel 44 of FIG. 3 requires additional painting
steps depending upon when the tube sheet 111 is installed in the cylindrical
section I OS of the vessel 44. Specifically, both sides of the tube sheet must
be
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coated with the protective material. After the bottom structure 103 is
installed
and welded onto the cylindrical section I05, the weld seam 109 must be coated.
Thus, the additional openings I 09 and manway opening 107 are provided to make
the necessary repairs to the inside surface of the vessel 44 along the weld
seam.
The preferred coating material for the vessels used to separate
hydrocarbon contaminants from water or non-acidic water are modif ed epoxy
phenolic materials. For example, a material sold under the trademark
CARBOLINE, Product No.187-0500 is a suitable material for a first coat for the
vessels 44, 100 and a material also sold under the trademark CARBOLINE,
ProductNo.187-C703 is suitable as a second coat. For vessels used in acid flow
back operations, the preferred coating materials are mica filled novalac vinyl
esters. A suitable material for a first coat is sold under the trademark
SENTRY
POLYMERS, Product No. 5302-HT and a suitable material for a second coat is
also sold under the trademark SENTRY POLYMERS, Product No. 5302-HT.
z 5 As shown in FIG. 5, an extremely dense number of stacks of
cartridges 104 is provided by the header 108. Specifically, the header 108, as
shown in FIG. 5, includes 23 openings 120, and therefore 23 porous conduits
106
and therefore 23 stacks 102 of cartridges I 04. Accordingly, the volumetric
flow
rate that can be handled by the vessel 100 is substantially greater than the
2 0 volumetric flow rate that can be handled by the vessel 44, Of course,
smaller
vessels with fewer stacks of cartridges and large vessels with more stacks of
cartridges are anticipated.
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Or~:anophilic Clav
The terms "organophilic clay" and "organoclay" are used herein
interchangeably to refer to various types of clay, e.g., smectites, that have
organoammonium ions substituted for cations between the clay layers. The term
"organoammonium ion substituted" refers to a substituted ammonium ion in
which one or more hydrogen atoms are replaced by an organic group. The
organoclays ~ are essentially solid compounds that have an inorganic and an
organic phase.
The preferred clay substrates for use in this invention are the
smectite-type clays, particularly the smectite-type clays that have a canon
exchange capacity of at least 75 milliequivalents per 100 grams of clay.
Useful
clays for such purpose include the naturally occurring Wyoming variety of
swelling bentonite and similar clays, and hectorite, which is a selling
magnesium-
lithium silicate clay. The clays are preferably converted to the sodium form
if
they are not already in this form. This can be effected by a cation exchange
reaction with a soluble sodium compound. These methods are well-known in the
art. Smectite-type clays prepared synthetically can also be utilized, such as
montmorillonite, bentonite, beidelite, hectorite, saponite, and stevensite.
The organoclays useful in this invention also include those set
2 0 forth in U.S. Patent No. 2,531,427 to Hauler. These organoclays are
modified
clays which exhibit inorganic liquid, some of those characteristics that
untreated
clays exhibit in water. For example, they will swell in many organic liquids
and
will form stable gels and colloidal dispersions.
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Generally, the quaternary ammonium salt substituted onto the clay
has organic groups attached to the clay that will range from aliphatic
hydrocarbon
of from 1 to 24 carbons to aromatic organic molecules, such as benzyl groups
that
could have a host of groups substituted on the benzyl ring. The number of
benzyl
versus straight chain hydrocarbons substituted on the ammonium ion can vary
from 3 to 0 aromatic substituents per aliphatic substituent (i.e., dimethyl
dioctododecyl 0:2, methyl benzyI dioctododecyl 1:2, dibenzyl dioctobenzyl 1:1,
tribenzyl octadecyl 3:1, and methyl dibenzyl octodecyl 2:1). The amount of
quaternary ammonium salt substituted on the clay can vary between 0.5% to 50%
1 o by weight.
Preferred organoclays useful in the invention comprises one or
more of the following types of quaternary ammonium canon-modif ed
montmorillonite, clays: .
R2
Montmorillonite'
R1 N R4
R3
wherein R~ is an alkyl group having at least 10 carbon atoms and up to, for
example, 24 atoms, and preferably having a chain length of from I2 to I 8
carbon
atoms; R2 is hydrogen, benzyl, or an alkyl group of at least 10 carbon atoms
and
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up to, for example, 24 carbon atoms, and preferably from 12 to 18 carbon
atoms;
and R3 and R4 are each hydrogen or lower alkyl groups, i.e., they contain
carbon
chains of from 1 to 4 atoms, and preferably are methyl groups.
Other organoclays utilizable in the invention include benzyl
organoclays such as dimethyl benzyl (hydrogenated tallow) ammonium bentonite;
methyl benzyl di(hydrogenated tallow) ammonium bentonite; and more generally
quaternary ammonium cation modified montrnorillonite clays represented by the
formula:
R~
Montmorillonite
R~ N - ~
R3
1 o wherein R1 is CH3 or C6HSCH=; RZ is C6HSCH2; and. R3 and R4 are alkyl
groups
containing long chain alkyl radicals having 14 to 22 carbon atoms, and most
preferably wherein 20% to 35% of said long chain alkyl radicals contain 16
carbon atoms and 60% to 75% of said long chain alkyl radicals contain 18
carbon
atoms.
The montmorillonite clays that may be so modified are the
principal constituents of bentonite rock, and have the chemical compositions
and
characteristics described, for example, in.Berry ~; Mason, "Mineralogy," 1959,
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- 27 -
pp. 508-509. Modified montmorillonite clays of this type (i.e., organoclays)
are
commercially available from Southern Clay Products, Inc., Gonzales, Tex. under
such trade designations as CLAYTONE 34 and 40, and are available from NL
Industries, Inc., New York, NY under such trade designations as BENTONE 27,
34, and 38. Other organoclays useful in the invention are the higher dialkyl
dimethyl ammonium organoclays such as dimethyl di(hydrogenated tallow)
ammonium bentonite; the benzyl ammonium organoclays, such as dimethyl
benzyl (hydrogenated tallow) ammonium bentonite; and ethylhydroxy ammonium
organoclays such as methyl bis(2-hydroxyethyl)octodecyl ammonium bentonite.
Oil-Adsorption Monitorin Probes
The organophilic clay adsorbs oil, grease and other hydrocarbon
contaminants and, after a period of time, which depends upon the flow rate and
hydrocarbon contamination level of the liquid contacting the organophilic
clay,
the clay becomes "spent"; or saturated with hydrocarbons to an extent that the
clay cannot further adsorb hydrocarbons to an extent that the effluent can be
legally disposed of back into the ocean. Presently, the regulations do not
permit
water to be returned to the ocean if it contains more than 29 ppm
hydrocarbons.
When the organophilic clay becomes spent, the waterloil mixture is directed
from
the cannister containing the spent clay and flow is contained through a
cannister
2 o containing fresh or regenerated organophilic clay.
In accordance with a preferred embodiment of the present
invention, it has been found that the organophilic clay within one or more
canisters 54 can be electronically monitored, continuously, or periodically,
to
detect when the organophilic clay is spent, or almost spent, e.g., within a
short
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safety factor of becoming spent, so that the water flow can be directed into
another cannister while regenerating or replacing the spent organophilic clay.
A waterproofprobe 60 (FIG. 6), having two diametrically opposed
non corrosive hollow circle conductor plates 62 and 64 extending from a probe
body 66, is embedded in the ~organophilic clay within one or more of the
filter
cartridges 55. The hollow circle probe conductor plates 62 and 64 are at a
"fixed"
distance from each other "d", e.g., from %z" to 1" apart. The probe conductor
body 66 preferably will be about 1" to 4" in length and extend from a probe
support structure 68. The probe support structure 68 will be affixed to a
central,
1 o treated-water outlet conduit 50, 51, 52, 53 or 54 of the cartridges~55
(see FIG. 3).
Electrical wires 70 encased in a watertight jacket 72 will extend from the
probe
body 66 and penetrate through a cable gland, 73A mounted in a cover 76 of
cartridge 55 through a packing gland connector 74. A cable jacket 72 provides
a waterproof seal around the electrical wires 70 and extends up from cartridge
55
. through the packing gland connector 74 and wires 70 will provide for
conveyance
of an electrical signal from the probe 60 through the cartridge 55 that houses
the
organophilic clay and, in a preferred embodiment, will convey the electrical
signal to a nearby probe junction box 80 which then connects to a
control/alarm
panel 81.
2 o It is estimated fihat a maximum of three probes per sump water
polishing unit (one per stack of cartridges 55) would provide adequate
sampling
to determine the adsorbed condition of organophilic clay in all of the
canisters.
After proper electrical connections have been accomplished, DC power is
applied
to the control/alarm panel 81 at a desired voltage. A precision calibrated
signal
2 5 is applied to the probes 60. When sea water or other non-hydrocarbon-
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29 -
contaminated reference water floods the cartridges 55, a measurement reference
is established. The precision voltage/frequency signal applied to the probes
60
may vary from a very low frequency bipolar wave up to a frequency in the
"ultrasonic" range.
As the organophilic clay begins to adsorb oil from the oily water
flowing through the cannister, the sea water is displaced and squeezed away
from
the electrical path of the hollow circle probe plates 62 and 64. The
conductance/resistance reference established from non-hydrocarbon-
contaminated water, e.g., sea water, flow is compared to the data measured as
the
oil is accumulatively adsorbed by the organophilic clay. Over time, the
dielectric
conductance/resistance path changes - the conductance decreases and the
resistance increases. The electrical path between the hollow circle probe
plates
62 and 64 slowly changes to a higher "dielectric" value, whereas the probe
plates,
dielectric and fixed distance between the plates 62 and 64 now become a
"capacitor". The resulting wave shape and/or signal level produced by the
capacitance and/or conductance ofthe media (hydrocarbon-containing sea water)
is evaluated by the controUalarrn panel 81. If the wave shape and/or signal
level
meet a predetermined criteria, the control circuitry of the panel 81 will
issue an
alarm signal (digital or analog) that can be audible and/or visual and can
signal
2 0 any telemetry or supervisory control and data acquisition (SCADA) system.
A preferred embodiment of a probe 1 SO is illustrated in FIGS. 7-
I0. Specifically, the probe body 150 includes two spaced apart elements 152,
154. Each hollow circle probe tip element 152,154 is connected to its own wire
lead 156, 158. The wire leads, which are insulated from one another, extend
2 5 through a protective j acket 160 and are connected to a probe junctionbox
80 and
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then connected to a control panel as shown in FIG. 6. The elements 152, 154
extend into the probe body 162 and are supported by a top cap 164. A bottom
cap
is shown at 166 which includes a key 168 for ensuring that the probe is
properly
aligned within the canister 104. Specifically, the probe is aligned so that
the
hollow circle probe tips 7 5?, 1 ~4 are aligned parallel to the radial flow of
fluid
thl'ULI~Th the canister. Orthogonal alignment of the hollow circle probe tips
152,
154 to the radial flow compromises the performance of the probe. The hollow
circle probe tip design allows full circulation of sea water through and
around the
surface area of the probe tips enabling a reliable measurement sample of the
1 o media. As shown in FIG. 10, each probe preferably includes a hollow circle
portion I70 connected to a downwardly protruding shaft 172. The preferred'
material for the elements 152, 154 is 316 stainless steel. Another suitable
material is HasteloylLncanel. The probe body tube 2 62, top cap 164 and bottom
cap 166 are made from Hylar thermoplastic fluoropolymer. The probe tube 162
is about two-thuds filled with a potting compound. ~ One suitable potting
compound is sold by the Minnesota Mining and Manufacturing Company under
the trademark DP270 (Black Potting Compound).
FIGS. 1 I, 12 and 14 illustrate a typical filter cartridge 104. Each
cartridge includes a permeable outer cover 130, a permeable iruier tube 132,
an
2 D annular top 134 and an annular bottom 136. The space defined by the cover
130,
tube 132, top 134 and bottom 136 is filled with organophilic clay. Handles 13
8,
140 are provided to facilitate the removal of the cartridges 104 from the
conduits
106 for regeneration of the clay or replacement of the cartridges 104.
FIG. 13 is a sectional view of an annular bottom plate of a
cartridge 104. The outer cover 130 is accommodated between the lips 138, 140.
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The inner tube 132 is accommodated between the lips 142, 144. The probe 150
for evaluating the condition of the clay, or the fluid flowing through the
cartridge
104 is received in the opening 146.
From the above description, it is apparent that the objects and
advantages of the present invention have been achieved. While only certain
embodiments have been set forth, alternative embodiments and various
modifications will be apparent from the above description to those skilled in
the
art. These and other altenaatives are considered equivalents and within the
spirit
and scope of the present invention.
w
Y.
