Note: Descriptions are shown in the official language in which they were submitted.
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PATENT SPECIFICATION
CLEANING OF HYDROCARBON-CONTAINING MATERIALS WITH CRITICAL AND SUPERCRITICAL
SOLVENTS
INVENTOR: Ian Tunnicliffe and Raymond Mt. Joy
RELATED APPLICATION
This. application is a Continuation-in-Part of United States Patent
Application Serial
No.
10/066,291 filed 31 January 2002, which claims provisional priority to United
States
Provisional Application Serial No. 60/265,825 filed 1 February 2000.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to an efficient and cost effective method
for treating
hydrocarbon-containing materials to remove solids, water, sulfur and/or other
contaminants.
[0002] More particularly, the present invention relates to a method for
cleaning hydrocarbon-
containing materials including oil-containing materials such as well-fluids,
drilling fluids,
used oils, oil contaminated soils, or the like, under near critical, critical
and/or supercritical
conditions to produce a clean solid residue, an hydrocarbon residue and an
aqueous residue,
where the hydrocarbon residue is reusable, the solid residue is substantially
free of
hydrocarbons and aqueously extractable contaminants and the aqueous residue
can be further
cleaned to produce a purified water residue.
2. Description of the Related Art
[0003] Critical and supercritical extraction processes have been known for
some time.
Supercritical extraction has been used to clean oil and to desulfurize coal,
but the technique
has not been used to clean up drilling fluids so that the cutting are
substantially free of
hydrocarbon residue and/or aqueously soluble contaminants.
[0004] Thus, there is a need in the art for a method for cleaning drilling
fluids and solid
concentration derived therefrom generally via centrifugation to a purified
solid material
substantially free of hydrocarbon residues, drilling field chemicals and/or
water soluble
contaminants.
SUMMARY OF THE INVENTION
[0005] The present invention provides a solid residue substantially free of
organic and/or
non-organic water-soluble components, where the solid residue is derived from
critical and/or
supercritical extraction of a material including the solid, organic and/or non-
organic water-
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soluble components with a cleaning composition comprising CO, COz, HZO, lower
alcohols,
lower alkanes, lower alkenes or mixtures or combinations thereof.
[0006] The present invention provides a slurry residue substantially free of
organic
components, where the slurry residue is derived from near critical, critical
and/or supercritical
extraction of a material including the solid, organic and/or non-organic water-
soluble
components and water with a cleaning composition comprising CO, CO2, HzO,
lower
alcohols, lower alkanes, lower alkenes or mixtures or combinations thereof.
[0007] The present invention provides a water-insoluble liquid residue
substantially free of
solids and/or non-organic water-soluble components, where the liquid residue
is derived from
critical and/or supercritical extraction of a material including the solid,
organic and/or non-
organic water-soluble components with a cleaning composition comprising CO,
COz, HZO,
lower alcohols, lower alkanes, lower alkenes or mixtures or combinations
thereof.
[0008] The present invention provides a hydrocarbon residue substantially free
of solids
and/or water soluble components including organic and inorganic, water-soluble
components
or mixtures thereof, where the hydrocarbon liquid residue,is derived from
critical and/or
supercritical extraction of a material including the solid, organic and/or non-
organic water-
soluble components with a cleaning composition comprising CO, CO2, H20, lower
alcohols,
lower alkanes, lower alkenes or mixtures or combinations thereof.
[0009] The present invention provides a method for cleaning a solid material
including
contacting the mixture with a cleaning composition including CO, COz, HzO,
lower alcohols,
lower alkanes, lower alkenes or mixtures or combinations thereof under
conditions of
temperature and pressure sufficient to maintain the cleaning composition at,
near or above its
critical point for a time sufficient to achieve a desired degree of cleaning
of the solid material.
[0010] The present invention provides a method for cleaning a solid material
including
contacting the mixture with a cleaning composition including CO, COz, HzO,
lower alcohols,
lower alkanes, lower alkenes or mixtures or combinations thereof under
conditions of
temperature and pressure sufficient to maintain the cleaning composition at,
near or above its
critical point for a time sufficient to achieve a desired degree of cleaning
of the solid material
to form an organic residue and a mixture of water and the solid material,
which can be in the
form of an aqueous slurry, dispersion, suspension or other aqueous/solid
mixture.
[0011] The present invention provides a method for cleaning a mixture
including contacting
the mixture with a cleaning composition including CO, CO2, HZO, lower
alcohols, lower
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alkanes, lower alkenes or mixtures or combinations thereof under conditions of
temperature
and pressure sufficient to maintain the cleaning composition at, near or above
its critical point
for a time sufficient to achieve a desired degree of separation of the
mixture.
[0012] The present invention provides a method for cleaning a mixture
including contacting
the mixture including a solid component, a water-insoluble liquid component
and water with
a cleaning composition including CO, CO2, H20, lower alcohols, lower alkanes,
lower
alkenes or mixtures or combinations thereof under conditions of temperature
and pressure
sufficient to maintain the cleaning composition at, near or above its critical
point for a time
sufficient to achieve a desired degree of separation of the mixture into a
solid residue, a
water-insoluble liquid residue and an water-soluble liquid residue.
[0013] The present invention provides a method for cleaning a mixture
including contacting
,a :: ., , . .
the mixture including a solid component, a water-insoluble liquid, component
and water with
a cleaning composition including CO, COZ, H20, lower alcohols, lower alkanes,
lower
alkenes or mixtures or combinations thereof under conditions of temperature
and pressure
sufficient to maintain the cleaning composition at, near or above its critical
point for a time
sufficient to achieve a desired degree of separation of the mixture into a
solid residue, a
water-insoluble liquid residue and/or an water-soluble liquid residue, where
the solid residue
is substantially free of organic and aqueously soluble components, the water-
insoluble liquid
residue is substantially free of solids, water or water-soluble components,
and the water-
soluble liquid residue is substantially free of solids and water-insoluble
liquid components.
[0014] The present invention provides a method for cleaning a mixture
containing solids,
organics such as hydrocarbons, inorganics such as metal complexes,.and/or
water including
contacting the mixture with a cleaning composition including CO, CO2, HZO,
lower alcohols,
lower alkanes, lower alkenes or mixtures or combinations thereof under
conditions of
temperature and pressure sufficient to maintain the composition in a
supercritial state for a
time sufficient of achieve a desired degree of component separation.
[0015] The present invention provides a method for cleaning drilling fluids,
oil contaminated
soil, oil pit material, or the like including contacting a drilling fluid with
a cleaning
composition including CO, CO2, HzO, lower alcohols, lower alkanes, lower
alkenes or
mixtures or combinations thereof under near critical, critical or
supercritical conditions.
[0016] The present invention provides a method for cleaning used motor oils
including
contacting a used-motor oil with a cleaning composition including CO, CO2,
HZO, lower
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alcohols, lower alkanes, lower alkenes or mixtures or combinations thereof
under near
critical, critical or supercritical conditions, to produce a reusable motor
oil. Preferably, the
reusable motor oil is substantially clear in color and has the characteristic
of the motor oil
prior to the addition of one or more additives, especially polar and/or water
soluble additives.
The reusable motor oil also generally has a lower sulfur content that the
sulfur content found
in the used motor oil prior to cleaning.
[0017] The present invention provides a method for desulfurizing a hydrocarbon
fuel such
as fuel oil, gasoline, diesel fuel, jet fuel or similar hydrocarbon fuels
including contacting a
hydrocarbon fuel with a composition including CO, CO2, H20, lower alcohols,
lower alkanes,
lower alkenes or mixtures or combinations thereof under near critical,
critical or supercritical
conditions, to produce a hydrocarbon fuel having a sulfur content less than
the sulfur content
of the hydrocarbon fuel prior to cleaning. . ,
DESCRIPTION OF THE DRAWINGS
[0018] The invention can be better understood with reference to the following
detailed
description together with the appended illustrative drawings in which like
elements are
numbered the same:
[0019] Figure 1 depicts a schematic diagram of a preferred embodiment of a
batch type
apparatus for carrying out the process of this invention;
[0020] Figure 2 depicts a phase diagram for carbon dioxide;
[0021] Figure 3 depicts a graph depicting the pressure verses enthalpy
relationship for carbon
dioxide;
[0022] Figure 4 depicts a schematic diagram of a preferred embodiment of a
semi-batch
apparatus for carrying out the process of this invention;
[0023] Figure 5 depicts a schematic diagram of one preferred embodiment of a
continuous
apparatus for carrying out the process of this invention;
[0024] Figure 6 depicts a schematic diagram of another preferred embodiment of
a
continuous apparatus for carrying out the process of this invention;
[0025] Figures 7A&B depict a schematic diagram of two preferred embodiment of
a
continuous apparatus for cleaning contaminated solid including drilling
fluids, oil containing
soils, or the like of this invention, where the extraction unit is shown in
cross-section;
[0026] Figures 8A&B depict a schematic diagram of two preferred embodiment of
a
continuous multi-staged apparatus of this invention for cleaning and/or
desulfurizing used
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hydrocarbons including used motor oils or cleaning and/or desulfurizing
hydrocarbon fizels
including gasoline, fuel oil, diesel fuel, jet fuel or the like;
[0027] Figures 9A depict a schematic diagram of a preferred embodiment of a
continuous
multi-staged apparatus of this invention for cleaning a composition including
a solid material,
water, and a hydrocarbons or substantially water insoluble organics to form a
hydrocarbon
or organic residue substantially free of solids and/or water, a water residue
substantially free
of solid material and hydrocarbon, and a solid residue substantially free of
water and
hydrocarbon; and
[0028] Figures 9B depict a schematic diagram of a preferred embodiment of a
continuous
mufti-staged apparatus of this invention for cleaning a composition including
a solid material,
water, and a hydrocarbons or substantially water insoluble organics to form a
hydrocarbon
or organic residue substantially free of solids and/or water and a mixture of
water and the
solid material.
DETAILED DESCRIPTION OF THE INVENTION
[0029] The inventors have found that an efficient and cost effective process
for cleaning solid
materials and/or mixtures containing solid materials can be developed using a
cleaning
composition at, near or above is critical point. The processes of this
invention can produce
a solid residue substantially free of hydrocarbons, water soluble contaminants
and/or other
contaminants, a water-insoluble liquid residue substantially free of solids,
water-soluble
contaminants and/or other contaminants and a aqueous residue substantially
free of solids and
water-insoluble liquid contaminants.
[0030] The present invention broadly relates to a process for cleaning solids,
dispersions,
slurries, and/or liquids under near critical, critical or supercritical fluid
extraction where the
extracting fluid includes Xe, NH3, lower aromatic including benzene and
toluene, nitrous
oxide, water, CO, CO2, H20, lower alcohols including methanol, ethanol,
propanol, and
isopropanol, lower alkanes including methane, ethane, propane, butane, pentane
and hexane,
petroleum ether, lower alkenes including ethylene and propylene or mixtures or
combinations
thereof.
[0031] The process is ideally suited for cleaning drilling fluids, reactor
sludge, oil-
contaminated soils, oil contaminated water, used oil, hydrocarbon fuels such
as diesel fuel,
jet fuel and other similar hydrocarbon fuels, extracting oils from tar sands
or the like, tanker
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bottoms, refinery bottoms, pit residues, refinery waste streams, refinery
residue streams or
the like. The pit residue include any material that comprises oil and solid
materials such as
soil, dirt or the like. The pit residue is generally associated with refining
and/or separation
and/or processing of crude oil streams. The present invention can also be used
to extract
hydrocarbon material out of paint wastes, polymer waste or any other chemical
processing
waste or waste stream that contains hydrocarbon materials, solid materials,
water and/or other
components that are amenable to near critical, critical and/or supercritical
extraction.
[0032] The process results in purified hydrocarbons, purified solids, and/or
purified water.
However, near critical, critical and/or supercritical extraction is generally
combined with
other downstream water purification process to produce a purified water.
[0033] Drilling fluids are complex compositions that are the by-product of oil
well drilling
operations. These fluids can include solids from drilling, operations, muds or
other additives
or compounds used in drilling operations, greases, anti-seize.compounds,
hydrocarbons from
hydrocarbon bearing formations, water, heavy metals, fracturing compositions,
proppants, or
other ingredients and mixtures and combination thereof. Drilling fluids can be
in the form
of a mixture of liquids and solids, a dispersions, a suspension, an emulsion,
or any other
liquid like mixture of solids and liquids.
[0034] Drilling fluid solids are solids obtained from an initial separation of
solids from liquid
components of a drilling fluid mixture. The solids are generally obtained via
centrifugation
of the drilling fluids as is well-known in the art. The solids generally have
the appearance of
a tar like material, but can be any solid like material derived from a process
which removes
most liquid material from the drilling fluids.
[0035] The process is also ideally suited for cleaning hydrocarbon-containing
fuels such as
diesel fuel, jet fuel, home heating oil and other similar hydrocarbon fuels,
or even gasoline.
The process results in purified hydrocarbon-containing fuels having reduced
sulfur contents
and a sulfur containing residue. The fuel to be treated is contacted with a
treating solvent or
composition under near critical, critical and/or supercritical conditions of
temperature and
pressure. The treatment temperature is usually from about 100°to about
400°C.
[0036] The process is also ideally suited for cleaning used motor oils to
produce a reusable
motor oil. Because the cleaning process removes material that are polar, many
to all of the
polar additives may be removed during the extraction system. Therefore, in one
preferred
reusable oil product of this invention, additives or additive packages are
added into the
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cleaned oil. These additives can include any additive currently added to motor
oils to
improve their detergent properties or other properties.
[0037] Suitable extracting fluid include, without limitation, Xe, NH3, lower
aromatic such as
benzene, toluene, or xylene , nitrous oxide, water, CO, CO2, H20, lower
alcohols such as
methanol, ethanol, propanol, or isopropanol, lower alkanes such as methane,
ethane, propane,
butane, pentane hexane, or petroleum ether; lower alkenes such as ethylene or
propylene; or
mixtures or combinations thereof. Preferably, the extracting fluid includes
carbon dioxide,
water, lower alkanes, lower alcohols, or mixture or combinations thereof.
Particularly, the
extracting fluid comprises a major portion of COZ and a minor portion of a
secondary fluid
selected from the groups consisting of Xe, NH3, lower aromatics, nitrous
oxide, water, CO,
HZO, lower alcohols, lower alkanes, lower alkenes and mixtures or combinations
thereof,
where a major portion means greater than SO mol% carbon dioxide, preferably,
greater than
70 mol% carbon dioxide, particularly, greater than 90 mol%.carbon dioxide, and
especially,
greater than 95 mol% carbon dioxide . More particularly, the extracting fluid
is exclusively
carbon dioxide.
[0038] Tabulated below are critical conditions for various supercritical
fluids:
Fluid Critical temperatureCritical pressureCritical Volume
Tc (K) Pc (MPa) Vc (cm3/mol)
Carbon dioxide304.14 7.375 94
Water 647.14 22.06 56
Ethane . 305.32 4.872 145.5
Ethene 282.34 5.041 131
Propane 369.83 4.248 200
Xenon 289.73 ~ 5.84 118
Ammonia 405.5 11.35 75
Nitrous oxide309.57 7.255 97
Fluoroform 299.3 4.858 133
Methanol 190.56 4.599 98.60
Isopropanol 508.3 4.764 222
Toluene 591.75 4.108 316
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[0039] For the purposes of this invention, the term substantially free means
that the cleaned
component includes less than or equal to about 5 wt% of any given contaminant,
preferably,
less than or equal to about 2.5 wt% of any given contaminant, particularly
less than or equal
to about 2 wt% of any given contaminant and especially less than or equal 1
wt% of any
contaminant.
[0040] The material-to-be-treated is contacted with treating solvent under
supercritical
conditions of temperature and pressure. The term, "supercritical,"
"supercritical state,"
"supercritical conditions," or "supercritical conditions of temperature and
pressure," refers
to a temperature above the critical temperature (Tc) of the solvent being
used, and a pressure
above the critical pressure (Pc) of the solvent being used. The treatment
temperature is
usually from 470°to 630°K. All temperatures herein will be given
in degrees Kelvin (°K) or
degree Celsius (°C) unless otherwise stated. Treatment according to
this invention is carried
out at a reduced temperature (Tr) from 1.0 to about 1.4, preferably from about
1.05 to about
1.3, and at a reduced pressure (pr) from 1.0 to about 2.0, preferably from
about 1.05 to about
1.5. The term, "critical," "critical state,""critical conditions" or "critical
conditions of
temperature and pressure," refers to a solvent at its critical temperature,
Tc, and its critical
pressure, Pc. The term, "near critical," "near critical state," ,"near
critical conditions" or "near
critical conditions of temperature and pressure," refers to a solvent at most
about 10°C below
its critical temperature, Tc, and at most about 10 psi below its critical
pressure, Pc, and
preferably, at most about 5°C below its critical temperature, Tc, and
at most about S psi below
its critical pressure, Pc.
[0041] The solvent to material-to-be-treated ratio for treatment according to
this invention
can range from about 0.2 to about 3 kilograms of solvent per kilogram of
material-to-be-
treated (Kg/Kg) preferably from about 0.3 to about 1.0 Kg/Kg. Actually, the
solvent to ,
material-to-be-treated ratio is a dimensionless number, since both the amount
of solvent and
the amount of material-to-be-treated are expressed on a weight basis.
[0042] The present invention can make possible the use of a much lower solvent
to material-
to-be-treated ratio than those used in prior art processes at the lower end of
the solvent to
material-to-be-treated range. However, the process of the present invention
can be operated
at any ratio to achieve a desired result.
[0043] The solvent flow rate is generally from about 0.2 to 3 kilograms per
hour of solvent
per kilogram of material-to-be-treated per hour (i. e. , 0.2 to 3 kg/kg-hr).
Preferably the solvent
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flow rate is about 0.5 kg/kg-hr. The time of treatment may range from about
0.5 to about two
hours, and is preferably about one hour.
[0044] The material-to-be-treated may be treated in either a single stage or
in plurality of
stages (i. e. , in two or more stages). In single stage extractions or
treatments, the composition
of the treating solvent remains uniform over the entire course of treatment,
and can be any
solvent described above, but is preferably carbon dioxide alone or in
combination with water,
a lower alcohol or a lower hydrocarbon. In plural stage extractions or
treatments, the
composition of the treating solvent can be the same or different from stage to
stage. For some
using mufti-staged treatment applications, the critical temperature of the
treating solvent used
in each stage increases progressively. Thus, the first stage solvent may be a
carbon dioxide;
next a mixture of carbon dioxide and water, or carbon dioxide and methanol;
the solvent for
the next stage may be, for example, a mixture of methanol and water with no
carbon dioxide
and so on. In extreme cases, the material-to-be-treated may be contacted
consecutively with
each of the treating fluids, i. e. , first with carbon dioxide, then with
methanol, and finally with
. .,,..
water, each in pure or substantially pure form. Whenever the composition of
the solvent is
varied over the course of treatment, the overall solvent , composition (based
on the total
quantities of each treating fluid used over the entire course of treatment) is
as stated above,
i.e., the mole fraction of carbon dioxide is from 0 to 0.5 (preferably 0.05 to
0.25), the mole
fraction of methanol is from 0.20 to 0.70 (preferably 0.30 to _0.50), and the
mole fraction of
water is from 0.20 to 0.70 (preferably 0.25 to 0.65).
[0045] In many of the preferred processes of this invention, carbon dioxide
alone is the
preferred extraction fluid. Thus, in multistage application, only the amount
of carbon dioxide
being supplied to each stage may vary. Again, the carbon dioxide supplied in
the first stage
progresses with the material-to-be-treated to the next stage. Thus as
additional carbon
dioxide is supplied, the ratio to carbon dioxide to the material-to-be-treated
changes.
Additionally, each stage can be operated at a different temperature and/or
pressure to achieve
a desired final product.
[0046] For solid type materials, a fixed bed, a moving bed reactor or other
similar reactors
can be used. Such reactor systems are described in more detail hereinafter.
When the
material-to-be-treated is a fluid (slurry, liquid, dispersion, suspension,
mixture, or the like)
at treatment temperature, a conventional stirred reactor or other type of
batch, semi-batch or
continuous reaction system can be used. For materials that include a large
amount of solids
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such as drilling fluids, a preferred continuous system includes a tube within
a tube within a
tube type reactor described in more detail in disclosure associated with
Figure 8. For
materials, such as used motor oil, which generally, do not include a large
amount of solids,
a preferred system includes a series of extraction units described in more
detail in the
disclosure associated with Figure 9. This same type of multi-staged systems is
ideally suited
for reducing the sulfur content of hydrocarbon based fuels.
[0047] This invention will be further described and illustrated with reference
to the drawings
which represent preferred embodiments of systems for carrying out the
processes of this
invention, i. e. , processes designed to convert drilling fluids are solids
therefrom into a cleaned
solid residue, a non-aqueous residue and an aqueous residue.
stem and System Operation
[0048] Referring now to Figure 1, a preferred embodiment of an extraction
system generally
100 for use in the present invention is shown to include a source of a
supercritical solvent
102, in this case carbon dioxide. The source 102 is connected to a sight glass
104 and a filter
106 via tubing 108. The tubing 108 is also connected to a rupture,disk relief
valve 110 for
safety purposes. The filter 104 is connected to a pump 112 having a back
pressure regulator
114 via tubing 108. The pump 112 is connected to a top entry 116 of an
extraction cell 118
via tubing 108 including a pressure gauge 120, a supply control valve 122 and
a second
rupture disk relief valve 124. The cell 118 includes a bottom entry 126 and a
sensor 128. The
top entry 116 is also connected to a top outlet valve 130 via tubing 108; the
bottom entry 124
is connected to a bottom outlet valve 132 and a bleed control valve 134, which
is intern
connected to a bleed valve 136. The top and bottom outlet control valves 130
and 132 are
connected to a separation vessel 138 via a separator control 140 and a heat
exchanger 142
including a second pressure gauge 144 and a bleed valve 146. The separator 138
includes a
sensor 148, a carbon dioxide outlet 150 and a cleaned material outlet 152
having a control
valve 154 which can be connected to a cleaned material container (not shown).
The carbon
dioxide outlet 150 connects to a used carbon dioxide venting line 156 includes
a back
pressure regulator 158, two filter 160, an flow regulator 162 and an exhaust
line 164, which
can be a recycle line by connecting the line to the pump 112. The entire
system is amenable
to computer control using standard computer control systems as are all of the
other systems
described herein.
[0049] The system of 100 operates by charging the cell 118 with a material-to-
be-treated.
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Once the cell 118 is charged, valves 130, 132, 134, and 136 are closed and
valve 122 is
opened to allow carbon dioxide to be pumped into the charged cell 118 via the
pump 112 until
a supercritical state is reached as indicated by the sensor 128. After the
extraction has been
allowed to run for a specified period of time, the valve 122 is closed and the
pump 112 is
generally turned off. After valve 112 is closed, the valves 130 and 132 are
opened allowing
the contents of the cell 118 to flow through valve 140, which reduces the
pressure of the
transferred contents, and the heat exchanger 140 to warm the contents up after
pressure
reduction and into the separator 138, via an inlet 139. In the seperator 138,
the now gaseous
carbon dioxide is taken out of separator 138 through outlet 150 via venting
line 156 and
associated equipment to either be exhausted to the air or recycled. The
cleaned material exits
the separator 138 through outlet 152 controlled by the control valve 154.
[0050] The system shown in Figure 1 is a preferred embodiment of an extraction
systems, but
is simply an illustrative example of a system for treating mixtures containing
solids,
hydrocarbons and water. Both the piping and fittings together with
instrumentation can be
configured in many different ways to obtain the same result.
[0051] In a batch type operation, a sample is placed into a cell. The cell is
then sealed and
the solvent is pumped into the cell under conditions of temperature and
pressure sufficient to
maintain the solvent at, near or above its critical point-near critical,
critical and supercritical
conditions. In a continuous operation, the solvent and the material to be
separated would be
continuously supplied to an extraction cell and solid-containing and liquid-
containing
residues would be continually removed from the cell. In either case, after
contacting the
solvent with the sample, the liquid phase is allowed to separate into an
organic phase and an
aqueous phase which can then be separated by conventional means such as
decantation,
stripping, distillation, or the like. The solids are either removed when the
cell is opened or
collected continuously for post extraction treatment.
[0052] In the examples that follow a batch extraction system as shown in
Figure 1 was used.
The cuttings samples were placed into the chamber and the chamber or cell was
then sealed.
Carbon Dioxide from a standard commercial cylinder was fed into the suction
side of the
pump. The pump was then switched on and the pressure of COZ was increased
until it
reached the critical point. The critical point of COz is a function of
temperature and pressure
as is the critical point for any other solvent system. For COz this dependence
is shown in
Figure 2. Figure 2 two is a standard phase diagram generally 200 for COZ is
shown to include
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a vapor region 202, a liquid region 204, a solid region 206 and the critical
point 208.
Referring now to Figure 3, a COZ pressure - enthalpy diagram generally is
shown. The super
critical fluid, COz, is fed into the extractor vessel whereupon the super
critical fluid diffuses
through the solids and removes the oil or hydrocarbons or other supercritical
COZ soluble
components, which contaminates the solid, into solution. The contaminants may
be minerals,
hydrocarbon (natural or synthetic). In the case of drilling fluid, the
contaminants will also
include additives to stabilize the drilling well fluids, including, without
limitation,
Polyalphaolefins, Acetals, Isomerised Olefins, Linear Alpha Olefins, Linear
Alkylbenzenes,
drilling muds or mixtures or combinations thereof or the like.
[0053] From the reactor vessel the solute loaded super critical fluid passes
through a heated
metering valve where it is depressurized and separation occurs, depositing the
extracted oil
and additives into the separation vessel. The super critical fluid (now in the
gas phase) is
exhausted to vent through a flow meter and totalizer. In a commercial full
scale operation,
the Carbon Dioxide gas or other fluid composition would be collected and fed
back to the
suction (low pressure) side of the pump, thereby creating a closed loop
system. Samples of
the extracted medium can be taken from the liquid phase to determine a desired
degree of
hydrocarbon removal. The chamber may require heating in certain circumstances.
(0054] The solid which was not taken into solution by the supercritical phase,
remains in the
reaction vessel for subsequent removal. After supercritical extration, the
solid residue not
only has reduced contaminants, preferably substantially no supercritically
soluble
contaminant, but is dry and a sterile.
[0055] Referring now to Figure 4, another preferred systems generally 400 for
performing
the extraction method of this invention is show where the extracting solvent
is a mixture of
carbon dioxide, pure water, and pure methanol. The pure water and pure
methanol are
contained in liquid form in feed reservoirs 402 and 404, respectively, having
exit flow control
valves 406 and 408, respectively. Liquid water and liquid methanol are
introduced from
reservoirs 402 and 404, respectively, into a liquid feed line 410. The
water/methanol mixture
is pumped through feed line 410 by means of a high pressure duplex
reciprocating piston
pump 412. This water/methanol mixture flows to a mixing tee 414.
[0056] Carbon dioxide is stored as a liquid under pressure in a pressure
vessel 416, which
may be a conventional gas cylinder. Carbon dioxide is withdrawn as a gas or
vapor from the
container 416 into a gas line 418. Carbon dioxide flow from the container 416
is controlled
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by a pressure regulator 420. The feed rate of carbon dioxide through the line
418 to the
extractor 422 is controlled by a mass flow controller 424 and a control valve
426. Carbon
dioxide is then passed through a pulse suppressor 428 and a feed pre-heater
430 to insure
smooth flow of the carbon dioxide stream to a gas compressor 432. Carbon
dioxide is then
compressed in the gas compressor 432 and the flow of compressed carbon dioxide
is
stabilized by passing it through a flow stabilizer 434. The carbon dioxide
stream flows from
the stabilizer 434 to the mixing tee 414.
[0057] The carbon dioxide stream is then mixed with the methanol/water mixture
in the
mixing tee 414. The combined mixture is then pre-heated in a feed pre-heater
436 to a
temperature close to but slightly below the desired reaction temperature. The
heated solvent
mixture is then fed via a solvent feed line 438 to the extractor 422, which
has a fixed or
stationary bed 440 therein. The fixed bed 440 is designed to contain an amount
of a
composition to be subjected to supercritical extraction, where the composition
is either
drilling solids from a centrifuge or drilling fluids directly for a well site.
[0058] The extractor 422 is of a generally vertical tubular shape - a
vertically disposed
tubular reactor, which is surrounded by a heating jacket 442 having an
electric heater 444
positioned therein: A foraminous plate 446 at a bottom 448 of the extractor or
reactor 422
supports the bed 440. The extractor 422 is provided with a rupture disc 450
and a pressure
gauge 452. The extractor 422 is also provided with a temperature sensor or
indicator 454,
which indicates the temperature in the bed 440, and a temperature controller
456, which
controls the current to the electric heater 444 in response to a reaction
temperature as sensed
by temperature indicator 454.
[0059] During extraction, the extractor is held under conditions of
temperature and pressure
sufficient to maintain the solvent at, near, but below or above the solvents
critical point -
maintained under near critical, critical or supercritical conditions - as it
passes downwardly
through the bed 440. The effluent exits the reactor 422 at an outlet 458 and
the effluent will
include the solvent and some or all components soluble in the solvent
(depending on the
degree of intended cleaning or treatment) from the material-to-be-treated in
the bed 440 such
as organics, inorganics or the other compounds soluble in the extraction
solvent under near
critical, critical or supercritical conditions. The rate of removal of the
exiting solvent is
controlled by a control valve 460, which may be a needle valve. The normally
liquid
components of the effluent, i.e., water, methanol, and liquids extracted by
the solvent are
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condensed by passage through a tubular condenser 462. The condenser 462 is
cooled by any
suitable means such as a dry ice-acetone bath 464. The condensed liquids may
be removed
periodically (e.g., at the end of a run) from the condenser 462 for analysis.
Uncondensed
gases, typically carbon dioxide and normally gaseous hydrocarbons, are vented
from the
condenser 462 through a vent line 466. These gases may be analyzed as desired
and the
carbon dioxide recovered for recycling. Additionally, the volatile
hydrocarbons can be
collected for further processing. The calorific value of the vent gases in the
line 464 may be
recovered, e.g., by combustion of the gas mixture, where the calorific value
is sufficient to
justify this. Of course, if the above reaction system is run using only one
solvent component,
then the other solvent component feed lines are simply turned off or by-
passed.
[0060] According to a preferred embodiment of a process of this invention,
centrifuged
drilling solids and/or fluids are charged to the reactor 422 prior to the
start of a run. Water,
methanol and carbon dioxide are fed to the reactor 422 in desired proportions,
which can run
from pure carbon dioxide, pure methanol, pure water or any mixture or
combination thereof.
The respective feed rates are controlled by means of the valves 406 and 408
and the mass
flow controller 424. The solvent feed mixture is pre-heated in pre-heater 436
to a temperature
just below the critical temperature of the solvent composition. The solvent
mixture is passed
downwardly through the bed 440 in the reactor 422, where it is operated under
conditions of
temperature and pressure sufficient to maintain the solvent near its critical
point, at ites
critical point or above its critical point - near critical condition, critical
conditions or
.supercritical conditions - by means of external heat supplied by the electric
heater 444. The
effluent exiting the reactor 422 includes the solvent and all solvent soluble
components with
the solid being left in the bed 440 is continuously removed and is condensed
as previously
described. A run is allowed to proceed either for a predetermined length of
time or for a
length of time determined by some other parameter, such as instantaneous
effluent analysis.
Normally the solvent composition, i. e., the relative proportions of water,
methanol and carbon
dioxide, will remain constant throughout a run. This mode of operation may be
described as
semi-batch, since the solids and/or fluids are charged to and the solids are
discharged from
the extractor 422 before and after a run, respectively, in accordance with
batch operation
principles, while the solvent mixture is fed continuously throughout a run. Of
course, the
reaction can be run with non-continuous solvent feed, which would be under
purely batch
operating principles.
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[0061] Semi-batch operation as described in Figure 4 may be carried out in two
or more
stages, using solvents of different compositions in each stage. The solvent
used in each stage
may be Xe, NH3, lower aromatic including benzene and toluene, nitrous oxide,
water, CO,
COz, HzO, lower alcohols including methanol, ethanol, propanol, and
isopropanol, lower
alkanes including methane, ethane, propane, butane, pentane and hexane,
petroleum ether,
lower alkenes including ethylene and propylene or mixtures or combinations
thereof. Using
valves and flow controllers, an operator can pass a solvent of any desired
composition into
an appropriate extractor. When more than one stage is used, the first stage
(the earliest
portion of the run) typically uses the most volatile solvent (i. e. , the
solvent having the lowest
critical temperature), and the solvent or solvent mixtures used in subsequent
operating stages
typically have progressively higher critical temperatures. However, each stage
can use the
same solvent composition.
[0062] The present invention can also be operated under continuous operating
conditions
using reactors systems such as those illustrates in Figures 5 and 6. Referring
now to Figure
5, a preferred continuous system generally 500 for performing the extraction
method of this
invention is shown to include a stirred high-pressure vessel 502, which serves
to mix the
material-to-be-treated such as drilling fluids or a solids with the solvent.
The material-to-be-
treated and the supercritical extraction solvent are fed to the vessel 502 via
a feed line 504 and
a solvent feed line 506, respectively. The solvent entering through the line
506 is a solvent
selected from the group consisting of Xe, NH3, lower aromatic including
benzene and toluene,
nitrous oxide, water, CO, COZ, HZO, lower alcohols including methanol,
ethanol, propanol,
and isopropanol, lower alkanes including methane, ethane, propane, butane,
pentane and
hexane, petroleum ether, lower alkenes including ethylene and propylene or
mixtures or
combinations thereof. The resulting slurry, dispersion ro mixture is then
pumped by a high-
pressure slurry pump 508 through a feed preheater 510, which serves to heat up
the mixture
to a temperature just below the extraction temperature. The preheated feed is
then admitted
through a ball valve 512 or other similar device into a supercritical
extractor 514 which is of
the stirred reactor design, a mixing extruder, or other similar high shear
mixing reactors. The
mixture containing the extracted non-solid components is passed through a
discharge valve
516 into a product cooler 518. The cooled product is next sent to a separating
vessel 520 in
which the gaseous product of extraction are separated from the cleaned solids
and the liquid
products. The gaseous product are either vented from the system 500 through
valve 522 or
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separated to recover carbon dioxide or to a system to recover hydrocarbons or
to recover fuel
equivalents thereof. The solid and liquid products are removed through a
valued discharge
line 524.
[0063] Referring now to Figure 6, another configuration for a continuous
supercritical
extraction system generally 600 for performing the extraction method of this
invention is
shown to include a storage hopper 602 containing a solid material-to-be-
treated such as
drilling solids, where a level of solids in the hopper 602 is controlled via a
solid level
indicator-controller 604. The solids are metered from the storage hopper 602
through a rotary
air lock feeder 606 or via a screw type extruder or other similar apparatus
into an extractor
608. A solvent mixture is fed into the extractor 608 through a solvent feed
line 610. This
solvent is selected from the group consisting of Xe, NH3, lower aromatic
including benzene
and toluene, nitrous oxide, water, CO, CO2, H20, lower alcohols including
methanol, ethanol,
propanol, and isopropanol, lower alkanes including methane, ethane, propane,
butane, pentane
and hexane, petroleum ether, lower alkenes including ethylene and propylene or
mixtures or
combinations thereof, which may be formed, pressurized and preheated to just
below the
critical temperature as described with reference to Figure S. The solvent can
be analyzed for
compositional makeup using a gas chromatograph 612. The system shown in Figure
6 differs
from that shown in Figure 5 in that the system of Figure 5 can be operated
only co-currently,
while the system of Figure 6 can be operated either under counter-current or
co-current flow
conditions. A mixture of extracted and cleaned solids discharged from the
extractor 608 is
cooled in a product cooler 614 before being let down through a valve 616 into
a product
separating vessel 618. In this vessel, the gaseous products of extraction are
separated from
the cleaned solids and the liquid products. The gaseous product is then vented
from the
system through a valve 620. The cleaned solids.and liquid products are
discharged through
a valve 622 and separated as described above.
[0064] Referring now to Figures 7A&B, a preferred configuration for a
continuous
supercritical extraction system, generally 700, for performing the extraction
method of this
invention for solid and/or slurry materials is shown to include an input
container 702
containing a solid material-to-be-extracted 703 such as drilling fluids.
[0065] The solids are metered from the container 702 through a
control/metering system 704
into an extractor 706 via lines 707, where the control/metering system 704 can
be a pump, a
rotary air lock feeder, a screw type extruder, a value, or other
control/metering apparatus. It
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the container 702 is pressurized, the controller 704 can be a remote
controlled valve, but
generally, the controller 704 is a pump.
[0066] The extractor 706 comprises a tube within a tube within a tube type
extractor. The
extractor 706 includes an outer column or tube 708a, a semi-permeable membrane
710, a
lower section 712a and an upper section 712b. The upper section 712b includes
a closed
ended, inverted middle tube 708b and an inner tube 708c. The extractor 706
also includes
a material-to-be-extracted inlet 714 connected to one of the lines 707 from
the controller
704A. The inlet 714 passes through the membrane 710 delivering the material-to-
be-
extracted 703 into an interior 716 of the inner tube 708c from the container
702. The dashed
lines with arrows indicate the direction of material flow in the extractor
706. The inner tube
708c extends upward to form a first gap 718a between a top 720 of the inner
tube 708c and
an inner surface 722 of the closed end 724 of the middle tube 708b. The middle
tube 708b
extends downward to form a second gap 718b between a top 711 of the membrane
710 and
a bottom 726 of the middle tube 708b. While a third gap 718c is formed between
an outer
surface 728 of the closed end 724 of the middle tube 708b and an inner surface
730 of a top
732 of the column 708a. The inner surface 730 is shown here to include a
tapered section 731
to improve material flow out of the extractor 706. The gaps 718a, 718b and
718c may have
the same dimension or may have different dimensions and are designed to
provide shear
mixing of the material-to-be-extracted and the extracting fluid as the
combined flow
progressed through the extractor 706 along the path indicated by the dashed
and arrowed
lines.
[0067] The extractor 706 also includes extraction fluid inlets 734a, 734b and
734c adapted
to supply an extraction fluid 736 from an extraction fluid supply system 738
to the extractor
706 via lines 735a-c. The inlet 734c supplies a first amount of extraction
fluid 736 into the
inner tube 708c at a position 740 near a top 715 of the inlet 714 via line
735c. The inlet 734b
supplies a second amount of extraction fluid 736 via line 735b into the middle
tube 708b at
a position 742. The position 742 can be at any desired location along the
middle tube 708b,
but is preferably located near the gap 718b. The inlet 734a supplies a third
amount of
extraction fluid 736 via line 735a into the outer tube 708a at a position 744.
Although the
position 744 can be located anywhere along the column 708a, it is preferably
located near the
gap 718b.
[0068] The supply system 738 includes an extraction fluid storage tank 746, a
compressor
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748, and a mass controller 750. The compressor 748 compresses the extraction
fluid 736 to
a desired pressure, which is preferably a pressure that is sufficient to
maintain the extraction
fluid in the extractor to be at or above the supercritical point for the
particular extraction fluid
being used. Looking at Figure 7A, the system 738 also includes separate valves
752a-c for
controlling the first, second, and third amount of extracting fluid flowing
into the extractor
706 through lines 735a-c and a fourth valve 752d controlling the amount of
extraction fluid
736 supplied, via line 735d, to a venturi valve described below. Looking at
Figure 7B, the
system 738 includes only a single valve 752 for controlling the amount of
extracting fluid
flowing into the extractor 706 through lines 735a-c and into the venturi valve
via line 735d.
In both Figures 7A&B, the supply system 738 also includes a recycle line 754.
[0069] As the material-to-be-extracted 703 is being feed and mixed with the
extraction fluid
736, any water and materials dissolved in the water migrate across the
membrane 710 into the
lower section 712a and exit the extractor 706 via a line 713 to an aqueous
phase storage tank
756 via a control valve 758a and a heat exchanger 758b, where the control
valve 758a
reduces the pressure to ambient pressure.
[0070] After the material-to-be-extracted 703 has been mixed with the three
portions of
extraction fluid 736 in the extractor 706, the combined mixture exits the
extractor 706 via exit
line 760 which interconnects the extractor 706 with a first separator 762. The
separator 762
allows the solids to sink to a bottom section 764a of the separator 762, while
the fluids
occupy a top section 764b of the separator 762. The separator 762 also
includes a venturi
valve 766 connected to an extraction fluid input 768 connected to the supply
line 735d from
the extraction supply system 738. As the extraction fluid 736 travels through
the venturi
value 766, the solids 770 are pulled into the venturi valve 766 and exit the
separator 762 to
a solids recovery system 772 via a solids outlet 771. The solids recovery
system includes a
solids storage vessel 772a connected to the separator 762 via lines 772b
having a pressure
reducing control valve 772c and a heat exchanger 772d. The separator 762 can
also include
a by-pass outlet 769 for the extraction fluid supplied to the venturi valve
766 via inlet 768.
[0071] The liquids, oils and extraction fluid, from the first separator 762
are forwarded to a
second separator 774 through two pressure-reducing control valves 776a&b and
two heat
exchangers 778a&b via lines 779. The second separator 774 includes hydrocarbon
liquid exit
line 780 connected to a hydrocarbon storage vessel 781 via control valve 782.
The second
separator 774 also includes probes 784, that determine the liquid level 785 in
the separator
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774, and an extraction fluid exit 786 connected to the extraction fluid
recycle line 754.
Additionally, the extraction fluid by-pass outlet 769 from the venturi valve
766 is directed via
line 788 to a by-pass valve 789 and a regulator valve 790 and combined with
the liquids from
the first separator 762 at the heat exchanger 778a.
[0072] The preferred extraction fluid for use in the extraction system 700 is
pure carbon
dioxide, but the extraction fluid can be selected from the group consisting of
Xe, NH3, lower
aromatic including benzene and toluene, nitrous oxide, water, CO, COZ, HzO,
lower alcohols
including methanol, ethanol, propanol, and isopropanol, lower alkanes
including methane,
ethane, propane, butane, pentane and hexane, petroleum ether, lower alkenes
including
ethylene and propylene or mixtures or combinations thereof, which may be
formed,
pressurized and preheated to just below the critical temperature as described
with reference
to Figure 5.
[0073] The apparatus of the present invention can be located remote from the
drilling site or
can be integrated into the drill complex. Thus, an off shore drilling platform
could have an
extraction unit built onto the pumping system for the drilling fluids so that
the solids and
aqueous components could be separated on the hydrocarbon components which
would
include mud ingredients could be fed back into the downhole fluid stream.
[0074] Referring now to Figure 8A, a preferred configuration of a continuous
supercritical
extraction system generally 800 of this invention for cleaning and/or
desulfurizing liquids
with only minor amount of solids therein, such as used motor oils or fuels, is
shown to include
a material-to-be-treated supply system 802. The material-to-be-treated supply
system 802
includes a material-to-be-treated reservoir 804 containing the material-to-be-
treated 806, a
pump 808 or any other apparatus for transferring a liquid material and a feed
line 810.
[0075] The system 800 also includes an extracting fluid supply system 812. The
extraction
fluid supply system 812 includes an extracting fluid reservoir 814 containing
an extraction
fluid 815, a compressor 816, an extraction fluid feed line 818 and a recycle
line 820.
[0076] The system 800 is a mufti-staged extraction/cleaning system shown in
Figure 8A to
have four extractors 822a-d in series and a separator 824. Each extractor 822
includes a
membrane 826 separating each extractor 822 into an upper section 828 and a
lower section
830. The membranes 826 allow water and polar compounds to migrated from the
upper
section 828 of each extractor into the lower section of each extractor. The
first extractor 822a
is connected to the material-to-be-treated feed line 810, while the other
three extractors 822b-
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d include a forwarding line 832, which feeds the extractors 822b-d with the
contents of the
upper section 828 of the preceding extractor 822a-c, i. e. , the contents of
the upper section 828
of the extractor 822a is the feed for the extractor 822b via forwarding line
832 and so on.
Finally, the contents of the upper section 828 of the extractor 822d are
forwarded to the
separator 824 via a separator feed line 834. Each extractor 822 also includes
an extractor feed
line 836 connected to the feed line 818. Looking at Figure 8B, each feed line
836 includes
a separate flow controlling valve 838, where the valves 838 allow the amount
of extraction
fluid 815 entering each extractor 822a-d to be separately controlled so that
the amount of
extraction fluid 815 being supplied to each extractor 822a-d can be different.
Each extractor
822a-d also includes an aqueous phase outlet 840 connected to a waste aqueous
storage
system 842 via waste lines 844. The storage system 842 includes a pressure
reduction valve
846 and a heat exchanger 848 to reduce the pressure to ambient pressure and
allow the
temperature to warm to room temperature and a waste water storage container
850. The
waste water can be forwarded to a water treatment facility for further
processing.
[0077] The separator 824 includes a finished product outlet 852 and an
extraction fluid outlet
854. The finished product outlet 852 is connected to a finished product
storage system 856
via finished product line 858. The finished product storage system 856
includes a pressure
reduction valve 860 and a heat exchanger 862 to reduce the pressure to ambient
pressure and
allow the temperature to warm to room temperature and a finished product
storage container
864. The extraction fluid outlet 854 is connected to the recycle line 820
passing through a
pressure reduction valve 866 and a heat exchanger 868 to reduce the pressure
to ambient
pressure and allow the temperature to warm to room temperature prior to mixing
with the
fresh extraction fluid going into the compressor 816.
[0078] In the following detailed description of Figures 9A&B, two preferred
reactor
schematics are shown for a continuous process for separating oil and other
organics (water
insoluble compounds) from mixtures including solid, water and oil or other
organics. The
mixture can be any mixture derived from oil and/or gas exploration and/or
productions such
as fresh drilling fluids, used drilling fluid (drilling fluids including
cutting and other solid
materials entrained in the drilling fluid during drilling operations), waste
pit materials which
generally includes oils and/or other organics, water, and solid such as soil,
cuttings, or other
solid materials.
[0079] The reactors schematics shown below are similar to the reactor
schematic of Figures
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8A&B combined with Figures 7A&B. The reactor system includes an extraction
fluid supply
system, a material-to-be-treated supply system, a reactor system and two or
three recovery
systems depending on the type of material the user wishes to recover. If the
user desires to
recover an organic fraction (hydrocarbons and other substantially water
insoluble organics),
an aqueous fraction and a dry solids fraction, then the user would use the
reactor system
shown in Figure 9A. If the user desires to recover only an organic fraction
and a mixed
fraction of water, water soluble materials and solids, then the user would use
the reactor
system shown in Figure 9B.
[0080] As will be discussed below, the advantage of using the reactor system
of Figure 9B,
is that with sufficient heating of the mixed fraction as it is withdrawn from
the reactor, each
reactor can be run on a continuous basis, without having to have a staged four
reactor system
configuration with each individual reactor running in a batch mode. It should
also be
recognized that with sufficient heating of the reactor components associated
with each
fraction withdrawal system, each reactor can be run continuously. However, for
convenience
and operational expediency, a staged reactor system may have advantages
because the staging
can be adjusted so that one reactor can be taken off line without
significantly affecting the
through put of the system.
[0081] Although a four reactor system is shown below, the preferred number of
reactors can
range from 1 to about 12 or higher, with 2 to 10 being preferred, 3 to 8 being
particularly
preferred and 4 to 8 being especially preferred. When the reactor system is
run as a group of
batch reactors, the sequence of events for each reactor is staggered so that
the entire process
is continuous. Although the reactors can be scaled to any desired size and can
have any
desired properties, one preferred reactor design has the following properties
or characteristics:
Property/CharacteristicValue Property/CharacteristicValue
Max. Working Pressure4,000 psigWorking Volume 94 gallons
Height 48 inches Freeboard Volume 47 gallons
Diameter 24 inches Plenum under filter 11.75 gallons
Volume
Freeboard 24 lnCheSa'/2 inch Outlets 7
Plenum number Filter 6 inChesa 1 inch Outlets
1
Parallel sides Max 78 inches 1'/4 inch Outlets 1
Height
Parallel sides Max 24 inches 1 Y2 inch Outlets 1
ID
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measured to dish shoulder
[0082] Using these reactor and system specifications, the reactor cycle
process is as follows:
(1) 12 minute fill time @ 8 gpm (gallons per minute); (2) 3 minutes
pressurization time; (2)
3 minute process time; and (4) 12 minute discharge time. These times give rise
to a per
reaction cycle time of 30 minutes. Thus, in a four reactor system, one reactor
can be
undergoing the process of each of the four steps so that the entire process is
continuous and
stagged. Of course, for 2 to 10 reactors, the start times of each reactor can
be staged to allow
continuous processing. Although an 8 gpm fill rate and discharge rate are
preferred, in
practice the fill and discharge rates can be varied considerably from about 4
gpm to about 20
gpm or lower or higher, preferably from about 6 to about 16, particularly from
about 6 to
about 12 and more particularly from about 6 to about 10.
[0083] The reactor systems of Figures 9A&B are designed to operate at
pressures between
about 800 psig (subcritical) to about 4000 psig (supercritical) at a
temperature between about
10°C and about 100°C, preferably between about 20°C and
about 50°C, particularly, between
about 20°C and about 40°C and more particularly between about
20°C and about 30°C or
ambient. Although each reactor can be designed to run continuously at
pressure, potential
difficulties can arise due to expansive cooling and the formation of solid
water or extraction
fluid (e.g., dry ice formation) during discharge or removal of desired
materials. These
potential difficulties can be overcome in at least two principle ways: (1)
provide sufficient
heat to each fraction recovery system to prevent or reduce ice formation or
(2) reduce the
pressure to below about 800 psig prior to discharge. At pressure between about
600 psig and
800 psig, ice formation (water or carbon dioxide) is greatly reduced and
smaller heat
exchanger can be used to prevent ice formation.
[0084] The process by which the reactors system operates in a batch mode
involves using
control values controlled by a controller attached either to a manual control
console or a
computer control console running scada processing systems as is well known in
the art, with
the computer control console being preferred with software sufficient to set,
monitor, change
and control reactor system parameters including the timing of opening and
closing valves.
At the start of each reactor cycle, the discharge valves of each reactor are
closed via their
controllers under computer or operator control.
[0085] First, fill valve associated with the material-to-be-treated supply
system is opened via
its controllers under computer or operator control, and the reactor is filled
with the
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appropriate amount of material-to-be-treated at a pressure below a pressure
that would cause
ice formation. After the material-to-be-treated has been charged, the material-
to-be-treated
fill valve is closed via its controllers under computer or operator control,
and the fill valve
associated with the extracting fluid supply system is then opened via its
controllers under
computer or operator control and at operating pressure. After the extracting
fluid has been
charged to the reactor, the extraction fluid fill valves is closed via its
controllers under
computer or operator control. All values remained closed during the extraction
process,
where non-aqueous fluids are separated from solids and aqueous fluids. After
the extraction
time has elapsed, the pressure is lowered to a pressure below the critical
pressure of the
extracting fluid (generally at or below about 750 psig) and the fraction
dispatch valves are
opened via their controllers under computer or operator control is a given
sequence.
[0086] Although the exact sequence is not critical, the preferred sequence of
opening of the
discharge valves is the non-aqueous (organics and extracting fluid) fraction
first by opening
and then closing its discharge valve via its controllers under computer or
operator control.
Next, the aqueous fraction second by opening and then closing its discharge
valve via its
controllers under computer or operator control, and followed by a dry,
powdered solids
fraction which is discharged by opening and then closing its discharge valve
via its controllers
under computer or operator control aided by a venturi valve in the reactor.
Each reactor
includes a water permeable screen member and/or membrane member in a lower
section of
the reactor so that the aqueous fraction goes into a lower portion of the
reactor below the
membrane and/or screen, the solid stay on the top of the member and the non-
aqueous
fraction occupies an upper portion of the reactor above the member. After the
fractions have
been discharged and their discharge valves opened and closed in the desired
sequence via
their controllers under computer or operator control, the process starts all
over again. By
staggering the cycle process for each reactor, the four reactors operate
similar to an internal
combustion engine where a sequence of pistons impart torque to the crank shaft
in
consecutive combustion events.
[0087] For reactor or reactor systems that do not require separation of the
aqueous fraction
from the solids fraction, but only require remove of all non-aqueous
components of the
material-to-be-treated, the water permeable member and the venturi valve and
associated lines
are removed, which converts the reactor from a three fraction discharge
configuration to a two
fraction discharge configuration. In the two fraction discharge configuration,
reactor charging
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proceeds exacting as above, which is the preferred manner of charging, because
the material-
to-be-treated is charged under relatively low pressure. Although high pressure
charging of
the material-to-be-treated is difficult because of the variability of the
composition and its
handling characteristics and the difficulty in equipment behavior for charging
such material
at high pressure. Of course, the pressure in each reactor can be raised or
lowered during the
course of the extraction process by adding or removing extracting fluid. Once
charging and
extraction are complete, the order of discharge is preferably the non-aqueous
fraction first
(organics and extracting fluid) and slurry second (water and solids). It
should be obvious to
an ordinary artisan that the aqueous phase will migrate to a lower portion of
the reaction due
to density as well the solid material.
[0088] Referring now to Figure 9A, a preferred configuration of a continuous
extraction
system generally 900 of this invention for cleaning solids such as drilling
fluids including
fluids that aid in the drilling operation and the fluids return from down hole
which include
solids, water and oil, is shown to include an extraction fluid supply system
902, a material-to-
be-treated supply system 920, a reactors system 940, an oil recover system
958, a water
recovery system 970 and a solids recovery system 980. While Figure 9B, shown
another
preferred continuous extraction system 900 includes the extraction fluid
supply system 902,
a material-to-be-treated supply system 920, a reactors system 940, an oil
recover system 958,
and a water-solids mixture recovery system 990. It should be recognized that
although
supercritical extraction is preferred, the reactor systems can be operated at
sub-critical, critical
and super-critical conditions. The reactor systems of Figures 9A&B also
include a heat
exchange system 1000 for exchanging heat between the extraction fluid
compression step
(exergonic or exothermic) and the discharge fraction step (energonic or
endothermic).
[0089] The extraction fluid supply system 902 includes an extracting fluid
supply reservoir
904 containing an extraction fluid 906, an intensifier 908 for comprising the
extracting fluid
to a desired pressure, a pressurized extracting fluid reservoir 910a,
extraction fluid feed lines
912, low pressure extraction fluid recycle lines 914, and a low pressure
recycle extracting
fluid reservoir 910b. The supply system 902 also includes extracting fluid
charging control
valves 916a-d and associated controllers 918a-d.
[0090] The material-to-be-treated supply system 920 includes a material-to-be-
treated supply
reservoir 922, a pressurization system 924 for charging the material-to-be-
treated via
material-to-be-treated supply lines 926. The supply system 920 also includes
material-to-be-
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treated charging control valves 928a-d and associated controllers 930a-d.
[0091] The reactors system 940 including four reactors or extractors 942a-d in
parallel. Each
reactor 942 includes a membrane 944 separating each reactor 942 into an upper
section 946
and a lower section 948. The membranes 944 allow water and polar compounds to
migrated
from the upper section 946 of each reactor 942 into the lower section 948 of
each reactor 942.
Each reactor 942a-d is connected to the extracting fluid supply system 902 via
supply lines
912, where charging is controlled by the control valves 916a-d and associated
controllers
918a-d. Each reactor 942a-d is also connected to the material-to-be-treated
supply system
920 via supply lines 926, where charging is controlled by the control valves
928a-d and
associated controllers 930a-d. As stated above, the control valves 916a-d and
928a-d and
their associated controllers 918a-d and 930a-d are timed to open so that the
material-to-be-
extracted is charged first at a low pressure, followed by high pressure
charging of the
extracting fluid. Once charged, each reactor 942 is held at pressure for a
specified period of
time at ambient temperature (preferred, although higher and lower temperatures
can be used
with concurrent pressure adjustment) to promote complete extraction. Of
course, the reactors
942 can also, and preferably do, include pressure sensors 950a-d, temperatures
sensors 952a-
d and level sensors 954a-d.
[0092] The oil recover system 958 includes a non-aqueous or oil fraction
outlet 959
connected to a separation tank 960 via oil fraction recovery lines 961
including an oil fraction
discharge valves 962a-d and their associated controllers 963a-d. The separator
tank 960
allows the extraction fluid to transition to the gas phase and includes an oil
outlet 964
connected to a finished product storage system 965 via finished product line
966. The tank
960 also includes an extracting fluid outlet 967 which is connected to the
extraction supply
system 902 via return lines 968.
[0093] The water recovery system 970 includes an aqueous fraction outlet 971
connected to
an aqueous fraction storage tank 972 via aqueous fraction recovery lines 973
including
aqueous fraction discharge valves 974a-d and their associated controllers 975a-
d.
[0094] The solids recovery system 980 includes a solids fraction outlet 981
connected to a
separation tank 982 via solids fraction recovery lines 983 including solids
fraction discharge
valves 984a-d and their associated controllers 985a-d and venturi valves 986a-
d located
inside the upper section 946 of the reactors 942. The separator tank 982
includes an
extracting fluid outlet 987 connected to the recycle lines 914 and a solids
outlet 988.
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(0095] Referring to Figure 9B, the reactors 942 do not include the membrane
944, the
aqueous recovery system 970 and the solids recovery system 980. Instead, the
water recovery
system 970 and the solids recovery system 980 are combined into a single water-
solids
mixture recovery system 990, where the system 990 includes a mixed fraction
outlet 991
connected to a storage tank 992 via mixed fraction recovery lines 993
including mixed
fraction discharge valves 994a-d and their associated controllers 995a-d.
[0096] In addition to the features and aspects of the reactor systems of
Figures 9A&B, the
reactor system also include a heat exchange system 1000. The heat exchange
system 1000
is adapted to utilize the heat generated during the extraction fluid
compressing step to warm
the reactor systems and recovery lines during the discharge process. The heat
exchange
system 1000 includes a first heat exchanger 1002 associated with the
intensifier 908 for
withdrawing heat generated in the compression step and carrying the heat via a
heat exchange
fluid through heat exchange lines 1004 to reactor heat exchangers 1006 and
recovery line heat
exchangers 1008. Thus, heat generated in transitioning the low pressure
extracting fluid (gas)
to high pressure extracting fluid (liquid) is used to counteract the cooling
due to the transition
of the extracting fluid from its high pressure state (liquid) to its low
pressure state (gas),
preventing ice and/or dry ice formation in the reactor or discharge lines or
valves during the
discharge process.
[0097] Although any extraction fluid described in this invention can be used
in the systems
of Figures 7A&B, 8A&B and 9A&B, the system preferably uses pure carbon
dioxide.
[0098] Additionally, if carbon dioxide is used in the extraction solvent
composition, then any
of the previously described installation can be equipped with a low
temperature separator for
separating carbon dioxide out of the atmosphere. Additionally, the apparatus
can have
recycling equipped to recover the extraction solvent for recycling.
EXPERIMENTAL RESULTS
[0099] The supercritical extraction solvent used in the following examples was
standard
commercial grade Carbon Dioxide, from a stock cylinder. The type of cell used
in the
following examples was an 8 mL stainless steel view cell. The pump type used
in the
following examples was a Milton Roy 100m1/hour max, positive displacement
pump. The
samples used in the following examples was a sample as received from Baker
Hughes and
was centrifuged cuttings from well fluids. In all of the examples the follow,
the oil removal
was estimated or derived by sight only.
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Examele 1
[0100] This example illustrates the cleanup of a sample of oil laden solids
obtained after well
fluids are subjected to centrifugation under supercritical conditions using
COZ at 3,500 psi.
[0101] The supercritical extraction cell and pipework were cleaned with
acetone. 1 g of the
sample was placed in the cell and the cell was reassembled. The cell was then
placed into
supercritrical pipe circuit. The cell and pipework were flushed twice with
stock Carbon
Dioxide. The pressure was then increased to about 3,500 psi at ambient
temperature. No
color change in liquid phase was noted. The pressure was held at about 3,500
psi pressure
for about 1 hour and 20 minutes. The total oil removed from the sample was
about 99%. The
solid material had a slight hydrocarbon sent, but dry to the touch.
Example 2
[0102] This example illustrates the cleanup of a sample of oil laden solids
obtained after well
fluids are subjected to centrifugation under supercritical conditions using
COz at 1,000 psi and
at 25°C.
[0103] The cell was cleaned and prepared as described in Example 1. After
preparation, the
pressure was increased to about 1000 psi at a temperature of about
25°C. The pressure and
temperature were maintained for about 1 hour. Under these conditions only
partial oil
removal was achieved with the recovery being about 60%.
Example 3
[0104] This example illustrates the cleanup of a sample of oil laden solids
obtained after well
fluids are subjected to centrifugation under supercritical conditions using
COZ at 2,000 psi and
at 27.8°C.
[0105] The cell was cleaned and prepared as described in Example 1. After
preparation, the
pressure was increased to about 2000 psi at a temperature of about
27.8°C. The pressure and
temperature were maintained for about 20 minutes. Under these conditions only
partial oil
removal was achieved with the recovery being about 85%.
Example 4
[0106] This example illustrates the cleanup of a sample of oil laden solids
obtained after well
fluids are subjected to centrifugation under supercritical conditions using
COZ at 2,500 psi and
at 22.5°C.
[0107] The cell was cleaned and prepared as described in Example 1. After
preparation, the
pressure was increased to about 2500 psi at a temperature of about
22.5°C. The pressure and
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temperature were maintained for about 10 minutes. Under these conditions only
partial oil
removal was achieved with the recovery being about 95%.
Example 5
[0108] This example illustrates the cleanup of a sample of oil laden solids
obtained after well
fluids are subj ected to centrifugation under supercritical conditions using
COZ at 3,500 psi and
at 43°C.
[0109] The cell was cleaned and prepared as described in Example 1. After
preparation, the
pressure was increased to about 3500 psi at a temperature of about
43°C. The pressure and
temperature were maintained for about 5 minutes. Under these conditions only
partial oil
removal was achieved with the recovery being about 95%.
Example 6
[0110] This example illustrates the cleanup of a sample of oil laden solids
obtained after well
fluids are subjected to centrifugation under supercritical conditions using
COZ at 2,500 psi and
at 43°C.
[0111] The cell was cleaned and prepared as described in Example 1. After
preparation, the
pressure was increased to about 2500 psi at a temperature of about
43°C. The pressure and
temperature were maintained for about 5 minutes. Under these conditions only
partial oil
removal was achieved with the recovery being about 95%.
Example 7
[0112] This example illustrates the cleanup of a sample of oil laden solids
obtained after well
fluids are subjected to centrifugation under supercritical conditions using
COZ at 2,500 psi and
at 23 °C.
[0113] The cell was cleaned and prepared as described in Example 1. After
preparation, the
pressure was increased to about 2500 psi at a temperature of about
23°C. The pressure and
temperature were maintained for about 5 minutes. Under these conditions only
partial oil
removal was achieved with the recovery being about 97%.
Example 8
This example illustrates the cleanup of a sample of oil laden solids obtained
after well
fluids are subj ected to centrifugation under supercritical conditions using
COZ at 2,500 psi and
at 23°C.
[0114] The cell was cleaned and prepared as described in Example 1. After
preparation, the
pressure was increased to about 2500 psi at a temperature of about
23°C. The pressure and
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temperature were maintained for about 2 minutes. Under these conditions only
partial oil
removal was achieved with the recovery being about80%.
Example 9
[0115] This example illustrates an analysis of a used oil after supercritical
cleanup using the
apparatus of this invention and COZ as the extracting fluid.
[0116] The following table lists the properties of the treated oil:
Test Common Name Test Units Results
ASTM D 482-95 Viscosity Index wt% 0.365
ASTM D 93 Flash Point by PMCC F 230+
ASTM D 1296-99 API Gravity @60F API 28.8
ASTM D 4077 Water Content vol% 6.32
ASTM D 445 Kinematic Viscosity cSt 24.470
@100F
ASTM D 4294-98 Total Sulfur wt% 0.327
Example 10
[0117] This example illustrates the comparison of used oil before and after
supercritical
cleanup using the apparatus of this invention and COZ as the extracting fluid.
[0118] The following table lists the properties of the oil before treatment:
Test Common Name Test Units Results
ASTM D 482-95 Ash Content wt% 0.365
ASTM D 93 Flash Point by PMCC F 230+
ASTM D 1296-99 API Gravity @60F API 28.8
ASTM D 4077 Water Content vol% 6.32
ASTM D 445 Kinematic Viscosity cSt 24.470
@100F
ASTM D 4294-98 Total Sulfur wt% 0.327
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[0119] The following table lists the properties of the oil after treatment:
Test Common Name Test UnitsResults
ASTM D 482-95 Ash Content wt% 0.005
ASTM D 93 Flash Point by PMCC F 190
ASTM D 1298 API Gravity @60F API 33.9
ASTM D 4052 API Gravity @60F API 33.9
ASTM D 4077 . Water Content vol% 0.08
ASTM D 445 Kinematic Viscosity cSt 2.904
@100C
ASTM D~445 Kinematic Viscosity cSt 11.62
@100F
ASTM D 445 Kinematic Viscosity 10.71
@40F
ASTM D 2887-97a Distillation, 99% RecoveryF 924
-
Ext'd
ASTM D 1500-98 Color ASTM L 2.0
ASTM D 2270-93 Viscosity Index 124
ASTM D 4530-93 Carbon Residue (micro <0.1
method)
ASTM D 4294-98 Total Sulfur wt% 0.244
ASTM 6762 Nitrogen mg/Kg 46.0
AAS by Acid DigestionIron ppm-wt 0.4
AAS by Acid DigestionNickel ppm-wt <0.1
AAS by Acid DigestionCopper ppm-wt 0.2
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Example 11
[0120] This example illustrates the comparison of used oil before and after
supercritical
cleanup using the apparatus of this invention and COZ as the extracting fluid.
[0121] The following table lists the properties of the oil after treatment:
Test Value Test Value
Viscosity Index. D-227085 Viscosity CST @40F, 31.38
D-
445
Appearance Clear & Pour Point, F, D-97 <-10
Bright yellow
liquid
Odor Petroleum Sulfur wt%, D-4294 0.2802
Viscosity SUS @210F, 43.0 Ash wt%, D-482 <0.001
D
Viscosity SUS @100F, 154.1 Color, D-1500 1.5
D-
445
Gravity API @ 31.8 Actual flash point, 400F
COC D-
92
Flash point, S.W. 230+ Metals 0.10
101, F
Example 12
[0122] This example illustrates the comparison of used oil before and after
supercritical
cleanup using the apparatus of this invention and COZ as the extracting fluid.
[0123] The following table lists the properties of the oil before and after
treatment:
Spec Before After Diff %Diff +/-
Ash 0.365 0.005 0.360 98.6 Decrease
Water 6.32 0.03 6.29 99.5 Decrease
Viscosity 24.47 2.904 21.566 88.1 Decrease
Flash 190 230 40 21 Increase
API Gravity28.8 33.9 5.1 17.7 Increase
Sulfur 0.337 0.244 0.093 27.7 Decrease
Example 13
[0124] This example illustrates the comparison of used oil before and after
supercritical
cleanup using the apparatus of this invention and COZ as the extracting fluid.
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[0125) The following table lists the properties of the oil before and after
treatment:
Spec Before After Diff %Diff +/-
Ash 0.4 0.02 0.38 95 Decrease
Water 6.4 0.4 6.0 93.75 Decrease
Flash 200+ 200+ ---- --- ---
Sulfur 0.3 0.3 --- --- ---
Example 14
(0126] This example illustrates the comparison of used oil before and after
supercritical
cleanup using the apparatus of this invention and COZ as the extracting fluid.
[0127] The following table lists the properties of the oil before and after
treatment:
Parameter Test Detection Before After
Method Limit
Gravity API@60F D-287 --- 28.2 29.7
Flash Point, F S.W. 1010 -10 BFO 380
Viscosity CST @40C D-445 1 24.37 35.63
Pour Point, F D-97 -10 <-10 <-10
Sulfur, wt% D-4294 0.0001 0.3116 0.3019
Ash, wt% D-482 0.001 0.315 0.004
Total Halogen, PPM D-808 1.0 617.2 10.6
PCB's, PPM S.W. 8082 0.05 BDL BDL
Water by distillation, D-95 0.05 6.4 <0.05
Vol%
Sediment by Extraction,D-473 0.01 0.05 <0.01
wt%
Heat of Combustion, D-240 10 17,761 19,302
BTU/lb
Heat of Combustion, D-240 60 131,04 141,07
BTU/gal 0 8
Carbon Residue Ramsbottom,D-524 0.01 --- 0.06
Wt%
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Heavy Metals PPM Method Detection Before After
Limit
Arsenic EPA-6010 0.0012 BDL BDL
Cadmium EPA-6010 0.001 S 0.113 0.014
Chromium EPA-6010 0.0040 0.525 0.007
Lead EPA-6010 0.0140 9.693 0.338
Nickel EPA-6010 0.0055 4.021 BDL
Sodium EPA-6010 0.0010 66.277 1.823
Vanadium EPA-6010 0.0020 0.030 0.015
Iron EPA-6010 0.0015 31.981 0.351
BDL- beyond detection limit; BFO- Blows flame out @200°F
Recovery, D-86Distillation, Recovery, D-86 Distillation,
F F
IBP 542 70% Recovery 728
5% Recovery 602 80% Recovery 740
10% Recovery 670 90% Recovery 756
20% Recovery 690 95% Recovery 788
30% Recovery 700 End Point 796
40% Recovery 708 Recovery ~ 98.0%
50% Recovery 714 Residue 1.5%
60% Recovery 718 Loss 0.5%
Example 15
[0128] This example illustrates the analytical data for the oil extracted from
a drilling fluid
under supercritical cleanup using the apparatus of this invention and COZ as
the extracting
fluid.
[0129] The following table lists the properties of the drilling fluid
recovered oil:
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Parameter Test Method Results
Gravity API@60F D-287 38.0
Flash Point, PMCC F D-93 148
Viscosity CST @100F D-445 2.73
Pour Point, F D-97 -5
Cloud Point, F D-2500 10
Sulfur, wt% D-4294 0.0615
Ash, wt% . D-482 <0.001
Color D-15 0.5
PCB's, PPM S.W. 8082 BDL
Water by distillation, Vol% D-95 <0.05
Sediment by Extraction, wt% D-473 <0.01
Carbon Residue Ramsbottom, wt% D-524 0.06
Carbon Residue Ramsbottom, wt% D-524 0.20
on 10%
residue
Cetane Index D-976 54.0
Bacteria Count, Counts/mL --- 0
Hea Metals PPM Method Before
Arsenic EPA-6010 BDL
Cadmium EPA-6010 BDL
Chromium EPA-6010 0.006
Lead EPA-6010 0.254
Nickel EPA-6010 BDL
Sodium EPA-6010 0.572
Vanadium EPA-6010 BDL
Iron EPA-6010 0.039
BDL- beyond detection limit; BFO- Blows flame out @200°F; same
detection limits as in
Example 14
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Recovery, D-86Distillation, Recovery, D-86 Distillation,
F F
IBP 354 70% Recovery 578
5% Recovery 396 80% Recovery 600
10% Recovery 408 90% Recovery 636
20% Recovery 438 95% Recovery 674
30% Recovery 460 End Point 698
40% Recovery 482
50% Recovery 528
60% Recovery 554
Accelerated Stability, Value
F 21-61
Initial Color 0.5
Final Color 1.0
Pad Rating (Blotter) 1
[0130] All references cited herein are incorporated by reference. While this
invention has
been described fully and completely, it should be understood that, within the
scope of the
appended claims, the invention may be practiced otherwise than as specifically
described.
Although the invention has been disclosed with reference to its preferred
embodiments, from
reading this description those of skill in the art may appreciate changes and
modification that
may be made which do not depart from the scope and spirit of the invention as
described
above and claimed hereafter.
