U.S. patent application number 14/451094 was filed with the patent office on 2014-12-04 for crude oil desulfurization.
The applicant listed for this patent is H R D Corporation. Invention is credited to Rayford G. ANTHONY, Gregory G. BORSINGER, Abbas HASSAN, Aziz HASSAN.
Application Number | 20140353112 14/451094 |
Document ID | / |
Family ID | 45568131 |
Filed Date | 2014-12-04 |
United States Patent
Application |
20140353112 |
Kind Code |
A1 |
HASSAN; Abbas ; et
al. |
December 4, 2014 |
CRUDE OIL DESULFURIZATION
Abstract
A method of removing sulfur from sour oil by subjecting sour oil
having a first sulfur content to high shear in the presence of at
least one desulfurizing agent to produce a high shear treated
stream, wherein the at least one desulfurizing agent is selected
from the group consisting of bases and inorganic salts, and
separating both a sulfur-rich product and a sweetened oil product
from the high shear-treated stream, wherein the sulfur-rich product
comprises elemental sulfur and wherein the sweetened oil product
has a second sulfur content that is less than the first sulfur
content. A system for reducing the sulfur content of sour oil via
at least one high shear device comprising at least one rotor and at
least one complementarily-shaped stator, and at least one
separation device configured to separate a sulfur-rich product and
sweetened oil from the high shear-treated stream.
Inventors: |
HASSAN; Abbas; (Sugar Land,
TX) ; HASSAN; Aziz; (Sugar Land, TX) ;
ANTHONY; Rayford G.; (College Station, TX) ;
BORSINGER; Gregory G.; (Chatham, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
H R D Corporation |
Sugar Land |
TX |
US |
|
|
Family ID: |
45568131 |
Appl. No.: |
14/451094 |
Filed: |
August 4, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13196519 |
Aug 2, 2011 |
8845885 |
|
|
14451094 |
|
|
|
|
61372013 |
Aug 9, 2010 |
|
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Current U.S.
Class: |
196/46 |
Current CPC
Class: |
C10G 2300/202 20130101;
C10G 2300/205 20130101; C10G 31/10 20130101; C10G 2300/308
20130101; C10G 31/09 20130101; C10G 19/02 20130101; B01F 7/00766
20130101; B01F 13/1016 20130101 |
Class at
Publication: |
196/46 |
International
Class: |
C10G 31/10 20060101
C10G031/10 |
Claims
1. A system for reducing the sulfur content of sour oil, the system
comprising: at least one high shear device comprising at least one
rotor and at least one complementarily-shaped stator and configured
to subject the sour oil and at least one liquid phase desulfurizing
agent selected from the group consisting of aqueous ammonia,
ammonium sulfate, and combinations thereof, to high shear and
produce a high shear-treated stream comprising sweetened oil and
elemental sulfur, wherein the at least one high shear device is
configured to subject the contents therein to a shear rate of at
least 10,000 s.sup.-1, wherein the shear rate is defined as the tip
speed divided by the shear gap, wherein the tip speed is defined as
.pi.Dn, where D is the diameter of the at least one rotor and n is
the frequency of revolution, and wherein the shear gap is the
minimum distance between the at least one rotor and the at least
one complementarily-shaped stator; and a separation device
configured for introduction thereto of the high shear-treated
stream, and extraction therefrom of a sulfur-rich product
comprising elemental sulfur, ammonium sulfate, or both; and a
sweetened oil product comprising sweetened oil, whereby the sulfur
is separated directly from the sweetened oil in elemental form, as
ammonium sulfate, or both.
2. The system of claim 1 wherein the at least one rotor is
configured to provide a tip speed of at least about 23 m/sec.
3. The system of claim 1 wherein the at least one rotor is
configured to provide a tip speed of at least 40 m/sec.
4. The system of claim 1 wherein the at least one rotor is
separated from the at least one stator by a shear gap of less than
about 5 .mu.m.
5. The system of claim 1 wherein the shear rate provided by
rotation of the at least one rotor during operation is at least
20,000 s.sup.-1.
6. The system of claim 1 further comprising one or more lines for
introducing at least one desulfurizing agent selected from bases
and inorganic salts, at least one API-adjustment gas comprising at
least one component selected from carbon monoxide, carbon dioxide,
hydrogen, methane, and ethane, or both desulfurizing agent and
API-adjustment gas into the sour oil upstream of the at least one
high shear device or directly into the at least one high shear
device.
7. The system of claim 1 further comprising a recycle line for
recycling at least one liquid phase desulfurizing agent from the at
least one separation device to the at least one high shear
device.
8. The system of claim 1 wherein the at least one separation device
is configured to provide a substantially dry sulfur product.
9. The system of claim 1 wherein the at least one high shear device
comprises at least two generators, wherein each generator comprises
a rotor and a complementarily-shaped stator.
10. The system of claim 9 wherein the shear rate provided by one
generator is greater than the shear rate provided by another
generator.
11. The system of claim 1 wherein the at least one separation
device is selected from the group consisting of centrifuges and
filtration devices.
12. The system of claim 11 wherein the at least one separation
device comprises a centrifuge.
13. The system of claim 1 wherein the system is a closed-loop
system.
14. The system of claim 1 configured as a mobile unit, a modular
unit, or both.
15. The system of claim 1 comprising no device selected from the
group consisting of external heating apparatus, distillation
apparatus, settling tanks, and combinations thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent application Ser. No. 13/196,519, filed Aug. 2, 2011, which
claims the benefit under 35 U.S.C. .sctn.119(e) of U.S. Provisional
Patent Application No. 61/372,013 filed Aug. 9, 2010, the
disclosure of each of which is hereby incorporated herein by
reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
BACKGROUND
[0003] 1. Technical Field
[0004] The present invention relates generally to the removal of
sulfur from oil. More particularly, the present invention relates
to a system and method for sweetening crude oil. Still more
particularly, the present invention relates to a system and method
for removal of sulfur from oil via high shear.
[0005] 2. Background of the Invention
[0006] Crude oil is generally associated with significant
quantities of hydrogen sulfide and contains various other organic
and inorganic sulfur compounds. Natural fossil fuels, such as crude
oil and natural gas, that contain a substantial concentration of
sulfur compounds, such as hydrogen sulfide, sulfur dioxide, and
mercaptans, are referred to as `sour.` Sulfur compounds may evolve
from fossil fuels over time and the evolution of these compounds
produces significant environmental and safety issues. Emissions of
various sulfur compounds, including hydrogen sulfide and sulfur
dioxide are regulated. Due to enhanced regulations and
restrictions, it is desirable to remove sulfur compounds from crude
oil.
[0007] There is an ever-increasing shortage of naturally-occurring
low sulfur crude oil. With the increasing emphasis on pollution
control and the resulting demand for low sulfur content petroleum
crude oil, a need for the economical production of sulfur-reduced
crude has arisen.
[0008] Besides meeting enhanced regulations and restrictions,
removal of sulfur from crude oil is desirable for other reasons.
Not only does the evolution of sulfur compounds from crude oil
produce significant environmental and safety issues, these
compounds may also attack metal components of the oil well, as well
as pipelines and storage tanks and downstream refinery apparatus.
This attack causes corrosion and/or brittleness of the metal
components. Additionally, in a refinery, downstream processes may
utilize catalysts which are sensitive to the presence of
sulfur.
[0009] In conventional oil refineries, sulfur is generally removed
after the crude oil has been fractionated. Sulfur removal typically
comprises utilization of various desulfurization processes, often
requiring extreme operating conditions, and incorporation of
expensive equipment, often associated with high maintenance costs.
Examples of prior art processes for conventional sulfur removal can
be found in U.S. Pat. Nos. 1,942,054; 1,954,116; 2,177,343;
2,321,290; 2,322,554; 2,348,543; 2,361,651; 2,481,300; 2,772,211;
3,294,678; 3,402,998; 3,699,037; and 3,850,745, the disclosure of
each of which is hereby incorporated herein in its entirety for all
purposes not contrary to this disclosure.
[0010] Accordingly, there is a need in industry for systems and
processes of removing sulfur from crude oil. Desirably, the system
and method allow sweetening of crude oil proximal the removal of
the oil from the earth. The system and method may also be utilized
to enhance the API gravity of the crude oil and/or for removal of
other impurities, such as heavy metals, from the crude oil.
SUMMARY
[0011] Herein disclosed is a method of removing sulfur from sour
oil, the method comprising (a) subjecting sour oil having a first
sulfur content to high shear in the presence of at least one
desulfurizing agent to produce a high shear treated stream, wherein
the at least one desulfurizing agent is selected from the group
consisting of bases and inorganic salts; and (b) separating both a
sulfur-rich product and a sweetened oil product from the high
shear-treated stream, wherein the sulfur-rich product comprises
elemental sulfur and wherein the sweetened oil product has a second
sulfur content that is less than the first sulfur content. In
embodiments, subjecting the sour oil to high shear in the presence
of the at least one desulfurizing agent (a) comprises subjecting
the slurry to a shear rate of at least 10,000 s.sup.-1. In
embodiments, subjecting the sour oil to high shear in the presence
of the at least one desulfurizing agent (a) comprises subjecting
the slurry to a shear rate of at least 20,000 s.sup.-1. In
embodiments, at least one desulfurizing agent is selected from the
group consisting of aqueous ammonia, sodium hydroxide, potassium
hydroxide, ammonium sulfate, calcium carbonate, hydrogen, hydrogen
peroxide, monoethanolamine (MEA), diglycolamine (DGA),
diethanolamine (DEA), diisopropanolamine (DIPA) and
methyldiethanolamine (MDEA). In embodiments, at least one
desulfurizing agent is selected from the group consisting of
ammonium sulfate and ammonium hydroxide.
[0012] In embodiments, the sour oil and the at least one
desulfurizing agent are provided in a ratio of about 50:50 volume
percent. In embodiments, the first sulfur content is in the range
of from about 0.5 to 6 weight percent. In embodiments, the second
sulfur content is less than 50% of the first sulfur content. In
embodiments, the second sulfur content is less than 10% of the
first sulfur content. In embodiments, the second sulfur content is
less than 0.5 weight percent. In embodiments, subjecting sour oil
to high shear (a) comprises introducing the sour oil and the at
least one desulfurizing agent into a high shear device comprising
at least one rotor and at least one complementarily-shaped stator.
High shear can comprise a shear rate of at least 10,000 s.sup.-1,
wherein the shear rate is defined as the tip speed divided by the
shear gap, and wherein the tip speed is defined as .pi.Dn, where D
is the diameter of the at least one rotor and n is the frequency of
revolution. In embodiments, high shear comprises a shear rate of at
least 20,000 s.sup.-1, wherein the shear rate is defined as the tip
speed divided by the shear gap, and wherein the tip speed is
defined as .pi.Dn, where D is the diameter of the at least one
rotor and n is the frequency of revolution.
[0013] In embodiments, subjecting the sour oil to a shear rate of
at least 10,000 s.sup.-1 produces a local pressure of at least
about 1034.2 MPa (150,000 psi) at a tip of the at least one rotor.
In embodiments, (a) comprises providing a tip speed of the at least
one rotor of at least about 23 m/sec, wherein the tip speed is
defined as .pi.Dn, where D is the diameter of the at least one
rotor and n is the frequency of revolution. In embodiments, the
shear gap, which is the minimum distance between the at least one
rotor and the at least one complementarily-shaped stator, is less
than about 5 .mu.m.
[0014] In embodiments, (a) comprises subjecting sour oil to high
shear in the presence of at least one desulfurizing agent and an
API-adjustment gas, wherein the API adjustment gas comprises at
least one compound selected from the group consisting of hydrogen,
carbon monoxide, carbon dioxide, methane and ethane. In
embodiments, the sour oil has a first API gravity, the sweetened
oil product has a second API gravity, and the second API gravity is
greater than the first API gravity. In embodiments, the
API-adjustment gas is selected from the group consisting of
associated gas, unassociated gas, FCC offgas, coker offgas,
pyrolysis gas, hydrodesulfurization offgas, catalytic cracker
offgas, thermal cracker offgas, and combinations thereof. In
embodiments, the high shear-treated stream comprises API-adjustment
gas bubbles having an average diameter of less than or equal to
about 5, 4, 3, 2 or 1 .mu.m. In embodiments, the API-adjustment gas
bubbles have an average diameter of less than or equal to about 100
nm.
[0015] In embodiments, the sour oil has a first API gravity, the
sweetened oil has a second API gravity, and the second API gravity
is greater than the first API gravity. The sour oil can be
extracted from the earth at a location proximal the location at
which the method is carried out. In embodiments, the sulfur-rich
product is yellow.
[0016] In embodiments, remaining after (b) (separating a
sulfur-rich product and a sweetened oil product from the high
shear-treated stream) is a remaining stream comprising at least one
desulfurizing agent, and the method further comprises (c) recycling
at least a portion of the at least one desulfurizing agent in the
remaining stream to (a). In embodiments, aqueous ammonia is
utilized in (a) during startup, ammonium sulfate is produced in
(a), separated in (b) and recycled in (c) to (a) as desulfurizing
agent, and aqueous ammonia is introduced in (a) only as needed to
maintain a desired second sulfur content.
[0017] In embodiments, the sour oil further comprises at least one
impurity selected from the group consisting of heavy metals and
chlorides. In embodiments, at least one of the at least one
impurities is separated from the high shear-treated stream with the
sulfur-rich product. In embodiments, the at least impurity is
selected from the group consisting of vanadium, mercury and
chlorides.
[0018] In embodiments, the sulfur-rich product is separated as a
substantially dry product. In embodiments, separating at (b)
comprises centrifugation, filtration or a combination thereof.
[0019] Also disclosed herein is a system for reducing the sulfur
content of sour oil, the system comprising: at least one high shear
device comprising at least one rotor and at least one
complementarily-shaped stator, and configured to subject the sour
oil to high shear and produce a high shear-treated stream
comprising sweetened oil, wherein the at least one high shear
device is configured to subject the contents therein to a shear
rate of at least 10,000 s.sup.-1, wherein the shear rate is defined
as the tip speed divided by the shear gap, and wherein the tip
speed is defined as .pi.Dn, where D is the diameter of the at least
one rotor and n is the frequency of revolution; and at least one
separation device configured to separate a sulfur-rich product and
sweetened oil from the high shear-treated stream.
[0020] In embodiments, the at least one rotor is configured to
provide a tip speed of at least about 23 m/sec. In embodiments, the
at least one rotor is configured to provide a tip speed of at least
40 m/sec. In embodiments, the at least one rotor is separated from
the at least one stator by a shear gap of less than about 5 .mu.m,
wherein the shear gap is the minimum distance between the at least
one rotor and the at least one stator. In embodiments, the shear
rate provided by rotation of the at least one rotor during
operation is at least 20,000 s.sup.-1.
[0021] The system can further comprise one or more lines for
introducing at least one desulfurizing agent selected from the
group consisting of bases and inorganic salts, at least one
API-adjustment gas comprising at least one component selected from
the group consisting of carbon monoxide, carbon dioxide, hydrogen,
methane and ethane, or one or more lines for introducing both
desulfurizing agent and API-adjustment gas into the sour oil
upstream of the at least one high shear device and/or directly into
the at least one high shear device.
[0022] The system can further comprise a recycle line for recycling
at least one desulfurizing agent from the at least one separation
device to the at least one high shear device. In embodiments, the
at least one separation device is configured to provide a
substantially dry sulfur product. In embodiments, the at least one
high shear device comprises at least two generators, wherein each
generator comprises a rotor and a complementarily-shaped stator.
The shear rate provided by one generator can be greater than the
shear rate provided by another generator. The at least one
separation device can be selected from the group consisting of
centrifuges and filtration devices. In embodiments, the at least
one separation device comprises a centrifuge.
[0023] In embodiments, the system is a closed-loop system. The
system can be configured as a mobile unit, a modular unit, or both.
In embodiments, the system comprises no device selected from the
group consisting of heating apparatus, distillation apparatus,
settling tanks and combinations thereof.
[0024] Certain embodiments of the above-described methods or
systems potentially provide overall cost reduction by providing for
reduced catalyst/desulfurizing agent usage, permitting increased
fluid throughput, permitting operation at lower temperature and/or
pressure, and/or reducing capital and/or operating costs. These and
other embodiments and potential advantages will be apparent in the
following detailed description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] For a more detailed description of the preferred embodiment
of the present invention, reference will now be made to the
accompanying drawings, wherein:
[0026] FIG. 1 is a schematic of a high shear system comprising an
external high shear mixer/disperser according to an embodiment of
the present disclosure.
[0027] FIG. 2 is a longitudinal cross-section view of a high shear
mixing device suitable for use in embodiments of the disclosed
system.
[0028] FIG. 3 is a box flow diagram of a method of removing sulfur
from oil according to an embodiment of this disclosure.
NOTATION AND NOMENCLATURE
[0029] As used herein, the term `dispersion` refers to a liquefied
mixture that contains at least two distinguishable substances (or
`phases`) that will not readily mix and dissolve together. As used
herein, a `dispersion` comprises a `continuous` phase (or
`matrix`), which holds therein discontinuous droplets, bubbles,
and/or particles of the other phase or substance. The term
dispersion may thus refer to foams comprising gas bubbles suspended
in a liquid continuous phase, emulsions in which droplets of a
first liquid are dispersed throughout a continuous phase comprising
a second liquid with which the first liquid is immiscible, and
continuous liquid phases throughout which solid particles are
distributed. As used herein, the term `dispersion` encompasses
continuous liquid phases throughout which gas bubbles are
distributed, continuous liquid phases throughout which solid
particles (e.g., solid sulfur or catalyst) are distributed,
continuous phases of a first liquid throughout which droplets of a
second liquid that is substantially insoluble in the continuous
phase are distributed, and liquid phases throughout which any one
or a combination of solid particles, immiscible liquid droplets,
and gas bubbles is distributed. Hence, a dispersion can exist as a
homogeneous mixture in some cases (e.g., liquid/liquid phase), or
as a heterogeneous mixture (e.g., gas/liquid, solid/liquid, or
gas/solid/liquid), depending on the nature of the materials
selected for combination. A dispersion may comprise, for example,
bubbles of gas (e.g. API-adjustment gas) and/or droplets of one
fluid (e.g., desulfurizing agent or oil) in a phase with which it
is immiscible (e.g., oil or desulfurizing agent).
[0030] Use of the phrase, `all or a portion of` is used herein to
mean `all or a percentage of the whole` or `all or some components
of.`
[0031] As used herein, for conciseness, the term "desulfurizing
agent" is utilized to include pH enhancers, which are compounds
that alter the pH of a solution when added thereto. That is, for
brevity, the term "desulfurizing agent" refers herein to
"desulfurizing agents and/or pH enhancers." As discussed further
hereinbelow, the desulfurizing agent may be basic or acidic. In
embodiments, the desulfurizing agent is a base. The desulfurizing
agent may be caustic. In embodiments, the desulfurizing agent is
selected from the group consisting of ammonia, sodium hydroxide,
potassium hydroxide, ammonium sulfate, calcium carbonate, hydrogen,
hydrogen peroxide, monoethanolamine (MEA), diglycolamine (DGA),
diethanolamine (DEA), diisopropanolamine (DIPA) and
methyldiethanolamine (MDEA). In embodiments, the desulfurizing
agent is aqueous ammonia. In embodiments, the desulfurizing agent
is 28% aqueous ammonia (28% NH.sub.4OH). In embodiments, the
desulfurizing agent comprises an inorganic salt. In embodiments,
the desulfurizing agent comprises calcium carbonate. In
embodiments, the desulfurizing agent comprises ammonium
sulfate.
DETAILED DESCRIPTION
[0032] Overview. Herein disclosed are a system and method for
sweetening oil. The oil to be sweetened may be crude oil or an oil
derived from crude oil. The system comprises an external high shear
mechanical device to provide rapid contact and mixing of reactants
in a controlled environment in the reactor/mixer device. Via the
disclosed system and method, hydrogen sulfide and sulfur compounds
in the oil can be removed as sulfur in dry (or substantially dry)
form without producing undesirable emissions. The system and method
may be utilized to remove sulfur from oil at the source (e.g., at a
wellsite). Desirably, the system is fully modular and/or mobile and
utilizable for sweetening sour crude oil proximal the source of the
crude. In embodiments, the system is operable as a closed loop.
[0033] In embodiments, the system and method allow desulfurization
of oil at substantially atmospheric global operating conditions.
Reduction in sulfur content effected by the disclosed system and
method may eliminate any need for further downstream
desulfurization processes.
[0034] A reactor assembly that comprises an external high shear
device (HSD) or mixer as described herein may decrease mass
transfer limitations and thereby allow the reaction, which may be
catalytic, to more closely approach kinetic limitations. Enhancing
contact via the use of high shear may permit increased throughput
and/or the use of a decreased amount of catalyst (e.g.,
ammonia/ammonium sulfate in certain embodiments) relative to
conventional processes and/or may enable reactions to occur that
would otherwise not be expected to occur.
[0035] High Shear System for Sweetening of Crude Oil. A high shear
system 100 for removal of sulfur from oil will now be described
with reference to FIG. 1, which is a process flow diagram of a high
shear system 100 according to an embodiment of this disclosure. The
basic components of a representative system include external high
shear device (HSD) 40 and separation unit(s) 10. Oil sweetening
system 100 may further comprise pump 5 and/or oil source 15. Each
of these components is further described in more detail below.
Desulfurization system 100 may be configured as a modular and/or
mobile unit (e.g., skid unit). Configuration as a modular/mobile
unit may be useful for utilization at a wellhead, for example.
Desulfurization system 100 may be designed for any desired
volumetric flow rate, for example, 100, 250, 500, 900, 1500, 2000,
3000, 4000, or 5000 gpm or more, or any range encompassed
therein.
[0036] Line 21 is connected to pump 5 for introducing feed
comprising crude oil into pump 5. Line 13 connects pump 5 to HSD
40, and line 19 carries a high shear-treated stream out of HSD 40.
Flow line 19 is any line into which the high shear-treated stream
from HSD 40 (comprising sweetened oil) flows. Separation unit(s) 10
is fluidly connected to HSD 40, for example via high shear-treated
product flow line 19. Separation unit(s) 10 may comprise one or
more outlets. For example, in the embodiment of FIG. 1, separation
unit(s) 10 comprises first separator outlet 16, second separator
outlet 17, and third separator outlet 20.
[0037] Additional components or process steps can be incorporated
between HSD 40 and separation unit(s) 10 or ahead of pump 5 or HSD
40, if desired, as will become apparent upon reading the
description of the high shear process hereinbelow. For example,
line 17 can be connected to line 21, line 22 or line 13, such that
material (e.g. pH enhancing and/or desulfurizing material) from
separation unit(s) 10 may be recycled to HSD 40. Sweetened crude
oil may be removed from system 100 via, for example, first
separator outlet 16.
[0038] In embodiments, one or more lines 22 are configured to
introduce desulfurizing agent reactant (e.g. ammonia) and/or
API-adjustment gas into HSD 40. Line(s) 22 may introduce fresh
reactant into HSD 40 directly or may introduce reactant into line
13.
[0039] High Shear Device 40. High shear oil desulfurization system
100 comprises one or more high shear devices 40. External high
shear device (HSD) 40, also sometimes referred to as a high shear
mixer, is configured for receiving an inlet stream, via line 13.
Line(s) 22 may be configured to introduce desulfurizing agent (e.g.
fresh or recycled from separation unit(s) 10) and/or API-adjustment
gas into HSD 40. Alternatively, HSD 40 may be configured for
receiving desulfurizing agent and crude oil via separate inlet
lines. Although only one HSD is shown for sweetening crude oil in
the embodiment of FIG. 1, it should be understood that some
embodiments of the system can comprise two or more HSDs. The two or
more HSDs can be arranged in either series or parallel flow. In
embodiments, crude oil sweetening system 100 comprises a single HSD
40.
[0040] HSD 40 is a mechanical device that utilizes one or more
generators comprising a rotor/stator combination, each of which has
a gap between the stator and rotor. The gap between the rotor and
the stator in each generator set may be fixed or may be adjustable.
HSD 40 is configured in such a way that it is capable of
effectively contacting the components therein at rotational
velocity. The HSD comprises an enclosure or housing so that the
pressure and temperature of the fluid therein may be
controlled.
[0041] High shear mixing devices are generally divided into three
general classes, based upon their ability to mix fluids. Mixing is
the process of reducing the size of particles or inhomogeneous
species within the fluid. One metric for the degree or thoroughness
of mixing is the energy density per unit volume that the mixing
device generates to disrupt the fluid particles. The classes are
distinguished based on delivered energy densities. Three classes of
industrial mixers having sufficient energy density to consistently
produce mixtures or emulsions with particle sizes in the range of
submicron to 50 microns include homogenization valve systems,
colloid mills and high speed mixers. In the first class of high
energy devices, referred to as homogenization valve systems, fluid
to be processed is pumped under very high pressure through a
narrow-gap valve into a lower pressure environment. The pressure
gradients across the valve and the resulting turbulence and
cavitation act to break-up any particles in the fluid. These valve
systems are most commonly used in milk homogenization and can yield
average particle sizes in the submicron to about 1 micron
range.
[0042] At the opposite end of the energy density spectrum is the
third class of devices referred to as low energy devices. These
systems usually have paddles or fluid rotors that turn at high
speed in a reservoir of fluid to be processed, which in many of the
more common applications is a food product. These low energy
systems are customarily used when average particle sizes of greater
than 20 microns are acceptable in the processed fluid.
[0043] Between the low energy devices and homogenization valve
systems, in terms of the mixing energy density delivered to the
fluid, are colloid mills and other high speed rotor-stator devices,
which are classified as intermediate energy devices. A typical
colloid mill configuration includes a conical or disk rotor that is
separated from a complementary, liquid-cooled stator by a
closely-controlled rotor-stator gap, which is commonly between
0.025 mm to 10 mm (0.001-0.40 inch). Rotors are usually driven by
an electric motor through a direct drive or belt mechanism. As the
rotor rotates at high rates, it pumps fluid between the outer
surface of the rotor and the inner surface of the stator, and shear
forces generated in the gap process the fluid. Many colloid mills
with proper adjustment achieve average particle sizes of 0.1 to 25
microns in the processed fluid. These capabilities render colloid
mills appropriate for a variety of applications including colloid
and oil/water-based emulsion processing such as that required for
cosmetics, mayonnaise, or silicone/silver amalgam formation, to
roofing-tar mixing.
[0044] The HSD comprises at least one revolving element that
creates the mechanical force applied to the reactants therein. The
HSD comprises at least one stator and at least one rotor separated
by a clearance. For example, the rotors can be conical or disk
shaped and can be separated from a complementarily-shaped stator.
In embodiments, both the rotor and stator comprise a plurality of
circumferentially-spaced rings having complementarily-shaped tips.
A ring may comprise a solitary surface or tip encircling the rotor
or the stator. In embodiments, both the rotor and stator comprise
more than 2 circumferentially-spaced rings, more than 3 rings, or
more than 4 rings. For example, in embodiments, each of three
generators comprises a rotor and stator each having 3 complementary
rings, whereby the material processed passes through 9 shear gaps
or stages upon traversing HSD 40. Alternatively, each of three
generators may comprise four rings, whereby the processed material
passes through 12 shear gaps or stages upon passing through HSD 40.
In some embodiments, the stator(s) are adjustable to obtain the
desired shear gap between the rotor and the stator of each
generator (rotor/stator set). Each generator may be driven by any
suitable drive system configured for providing the desired
rotation.
[0045] In some embodiments, HSD 40 comprises a single stage
dispersing chamber (i.e., a single rotor/stator combination; a
single high shear generator). In some embodiments, HSD 40 is a
multiple stage inline disperser and comprises a plurality of
generators. In certain embodiments, HSD 40 comprises at least two
generators. In other embodiments, HSD 40 comprises at least 3
generators. In some embodiments, HSD 40 is a multistage mixer
whereby the shear rate (which varies proportionately with tip speed
and inversely with rotor/stator gap width) varies with longitudinal
position along the flow pathway, as further described
hereinbelow.
[0046] According to this disclosure, at least one surface within
HSD 40 may be made of, impregnated with, or coated with a catalyst
suitable for catalyzing a desired reaction, as described in U.S.
patent application Ser. No. 12/476,415, which is hereby
incorporated herein by reference for all purposes not contrary to
this disclosure. For example, in embodiments, all or a portion of
at least one rotor, at least one stator, or at least one
rotor/stator set (i.e., at least one generator) is made of, coated
with, or impregnated with a suitable catalyst. In some
applications, it may be desirable to utilize two or more different
catalysts. In such instances, a generator may comprise a rotor made
of, impregnated with, or coated with a first catalyst material, and
the corresponding stator of the generator may be made of, coated
with, or impregnated by a second catalyst material. Alternatively
one or more rings of the rotor may be made from, coated with, or
impregnated with a first catalyst, and one or more rings of the
rotor may be made from, coated with, or impregnated by a second
catalyst. Alternatively one or more rings of the stator may be made
from, coated with, or impregnated with a first catalyst, and one or
more rings of the stator may be made from, coated with, or
impregnated by a second catalyst. All or a portion of a contact
surface of a stator, rotor, or both can be made from or coated with
catalytic material.
[0047] A contact surface of HSD 40 can be made from a porous
sintered catalyst material, such as platinum. In embodiments, a
contact surface is coated with a porous sintered catalytic
material. In applications, a contact surface of HSD 40 is coated
with or made from a sintered material and subsequently impregnated
with a desired catalyst. The sintered material can be a ceramic or
can be made from metal powder, such as, for example, stainless
steel or pseudoboehmite. The pores of the sintered material may be
in the micron or the submicron range. The pore size can be selected
such that the desired flow and catalytic effect are obtained.
Smaller pore size may permit improved contact between fluid
comprising reactants and catalyst. By altering the pore size of the
porous material (ceramic or sintered metal), the available surface
area of the catalyst can be adjusted to a desired value. The
sintered material may comprise, for example, from about 70% by
volume to about 99% by volume of the sintered material or from
about 80% by volume to about 90% by volume of the sintered
material, with the balance of the volume occupied by the pores.
[0048] In embodiments, the rings defined by the tips of the
rotor/stator contain no openings (i.e. teeth or grooves) such that
substantially all of the reactants are forced through the pores of
the sintered material, rather than being able to bypass the
catalyst by passing through any openings or grooves which are
generally present in conventional dispersers. In this manner, for
example, a reactant will be forced through the sintered material,
thus forcing contact with the catalyst.
[0049] In embodiments, the sintered material of which the contact
surface is made comprises stainless steel or bronze. The sintered
material (sintered metal or ceramic) may be passivated. A catalyst
may then be applied thereto. The catalyst may be applied by any
means known in the art. The contact surface may then be calcined to
yield the metal oxide (e.g. stainless steel). The first metal oxide
(e.g., the stainless steel oxide) may be coated with a second metal
and calcined again. For example, stainless steel oxide may be
coated with aluminum and calcined to produce aluminum oxide.
Subsequent treatment may provide another material. For example, the
aluminum oxide may be coated with silicon and calcined to provide
silica. Several calcining/coating steps may be utilized to provide
the desired contact surface and catalyst(s). In this manner, the
sintered material which either makes up the contact surface or
coats the contact surface may be impregnated with a variety of
catalysts. Another coating technique, for example, is metal vapor
deposition or chemical vapor deposition, such as typically used for
coating silicon wafers with metal.
[0050] In some embodiments, the minimum clearance (shear gap width)
between the stator and the rotor is in the range of from about
0.025 mm (0.001 inch) to about 3 mm (0.125 inch). The shear gap may
be in the range of from about 5 micrometers (0.0002 inch) and about
4 mm (0.016 inch). In embodiments, the shear gap is in the range of
5, 4, 3, 2 or 1 .mu.m. In some embodiments, the minimum clearance
(shear gap width) between the stator and the rotor is in the range
of from about 1 .mu.m (0.00004 inch) to about 3 mm (0.012 inch). In
some embodiments, the minimum clearance (shear gap width) between
the stator and the rotor is less than about 10 .mu.m (0.0004 inch),
less than about 50 .mu.m (0.002 inch), less than about 100 .mu.m
(0.004 inch), less than about 200 .mu.m (0.008 inch), less than
about 400 .mu.m (0.016 inch). In certain embodiments, the minimum
clearance (shear gap width) between the stator and rotor is about
1.5 mm (0.06 inch). In certain embodiments, the minimum clearance
(shear gap width) between the stator and rotor is about 0.2 mm
(0.008 inch). In certain configurations, the minimum clearance
(shear gap) between the rotor and stator is at least 1.7 mm (0.07
inch). The shear rate produced by the HSD may vary with
longitudinal position along the flow pathway. In some embodiments,
the rotor is set to rotate at a speed commensurate with the
diameter of the rotor and the desired tip speed. In some
embodiments, the HSD has a fixed clearance (shear gap width)
between the stator and rotor. Alternatively, the HSD has adjustable
clearance (shear gap width).
[0051] Tip speed is the circumferential distance traveled by the
tip of the rotor per unit of time. Tip speed is thus a function of
the rotor diameter and the rotational frequency. Tip speed (in
meters per minute, for example) may be calculated by multiplying
the circumferential distance transcribed by the rotor tip, 2.pi.R,
where R is the radius of the rotor (meters, for example) times the
frequency of revolution (for example revolutions per minute, rpm).
The frequency of revolution may be greater than 250 rpm, greater
than 500 rpm, greater than 1000 rpm, greater than 5000 rpm, greater
than 7500 rpm, greater than 10,000 rpm, greater than 13,000 rpm, or
greater than 15,000 rpm. The rotational frequency, flow rate, and
temperature may be adjusted to get a desired product profile. If
channeling should occur, and sulfur removal is inadequate, the
rotational frequency may be increased to minimize undesirable
channeling. Alternatively or additionally, high shear-treated
materials from a first HSD may be introduced into a second or
subsequent HSD 40.
[0052] HSD 40 may provide a tip speed in excess of 22.9 m/s (4500
ft/min) and may exceed 40 m/s (7900 ft/min), 50 m/s (9800 ft/min),
100 m/s (19,600 ft/min), 150 m/s (29,500 ft/min), 200 m/s (39,300
ft/min), or even 225 m/s (44,300 ft/min) or greater in certain
applications. In embodiments, the tip speed is in the range of from
about 5.1 m/s, 23 m/s or 50 m/s to about 23 m/s, 50 m/s, 100 m/s,
150 m/s 200 m/s or 225 m/s, or any range therein (for example, from
about 50 m/s to about 225 m/s). For the purpose of this disclosure,
the term `high shear` refers to mechanical rotor stator devices
(e.g., colloid mills or rotor-stator dispersers) that are capable
of tip speeds in excess of 5.1 m/s (1000 ft/min) or those values
provided above and require an external mechanically driven power
device to drive energy into the stream of products to be reacted.
By contacting the reactants with the rotating members, which can be
made from, coated with, or impregnated with stationary catalyst,
significant energy is transferred to the reaction. The energy
consumption of the HSD 40 will generally be very low. The
temperature may be adjusted as desired to effect desired sulfur
removal.
[0053] In some embodiments, HSD 40 is capable of delivering at
least 300 L/h at a tip speed of at least 22.9 m/s (4500 ft/min).
The power consumption may be about 1.5 kW. HSD 40 combines high tip
speed with a very small shear gap to produce significant shear on
the material being processed. The amount of shear will be dependent
on the viscosity of the fluid in HSD 40. Accordingly, a local
region of elevated pressure and temperature is created at the tip
of the rotor during operation of HSD 40. In some cases the locally
elevated pressure is about 1034.2 MPa (150,000 psi). In some cases
the locally elevated temperature is about 500.degree. C. In some
cases, these local pressure and temperature elevations may persist
for nano- or pico-seconds.
[0054] An approximation of energy input into the fluid (kW/L/min)
can be estimated by measuring the motor energy (kW) and fluid
output (L/min). As mentioned above, tip speed is the velocity
(ft/min or m/s) associated with the end of the one or more
revolving elements that is creating the mechanical force applied to
the fluid. In embodiments, the energy expenditure is at least about
1000 W/m.sup.3, 5000 W/m.sup.3, 7500 W/m.sup.3, 1 kW/m.sup.3, 500
kW/m.sup.3, 1000 kW/m.sup.3, 5000 kW/m.sup.3, 7500 kW/m.sup.3, or
greater. In embodiments, the energy expenditure of HSD 40 is
greater than 1000 watts per cubic meter of fluid therein. In
embodiments, the energy expenditure of HSD 40 is in the range of
from about 3000 W/m.sup.3 to about 7500 kW/m.sup.3. In embodiments,
the energy expenditure of HSD 40 is in the range of from about 3000
W/m.sup.3 to about 7500 W/m.sup.3. The actual energy input needed
is a function of what reactions are occurring within the HSD, for
example, endothermic and/or exothermic reaction(s), as well as the
mechanical energy required for dispersing and mixing feedstock
materials. In some applications, the presence of exothermic
reaction(s) occurring within the HSD mitigates some or
substantially all of the reaction energy needed from the motor
input. When dispersing a gas in a liquid, the energy requirements
are significantly less.
[0055] The shear rate is the tip speed divided by the shear gap
width (minimal clearance between the rotor and stator). The shear
rate generated in HSD 40 may be in the greater than 20,000
s.sup.-1. In some embodiments the shear rate is at least 30,000
s.sup.-1 or at least 40,000 s.sup.-1. In some embodiments the shear
rate is greater than 30,000 s.sup.-1. In some embodiments the shear
rate is at least 100,000 s.sup.-1. In some embodiments the shear
rate is at least 500,000 s.sup.-1. In some embodiments the shear
rate is at least 1,000,000 s.sup.-1. In some embodiments the shear
rate is at least 1,600,000 s.sup.-1. In some embodiments the shear
rate is at least 3,000,000 s.sup.-1. In some embodiments the shear
rate is at least 5,000,000 s.sup.-1. In some embodiments the shear
rate is at least 7,000,000 s.sup.-1. In some embodiments the shear
rate is at least 9,000,000 s.sup.-1. In embodiments where the rotor
has a larger diameter, the shear rate may exceed about 9,000,000
s.sup.-1. In embodiments, the shear rate generated by HSD 40 is in
the range of from 20,000 s.sup.-1 to 10,000,000 s.sup.-1. For
example, in one application the rotor tip speed is about 40 m/s
(7900 ft/min) and the shear gap width is 0.0254 mm (0.001 inch),
producing a shear rate of 1,600,000 s.sup.-1. In another
application the rotor tip speed is about 22.9 m/s (4500 ft/min) and
the shear gap width is 0.0254 mm (0.001 inch), producing a shear
rate of about 901,600 s.sup.-1.
[0056] In some embodiments, HSD 40 comprises a colloid mill.
Suitable colloidal mills are manufactured by IKA.RTM. Works, Inc.
Wilmington, N.C. and APV North America, Inc. Wilmington, Mass., for
example. In some instances, HSD 40 comprises the DISPAX
REACTOR.RTM. of IKA.RTM. Works, Inc.
[0057] In some embodiments, each stage of the external HSD has
interchangeable mixing tools, offering flexibility. For example,
the DR 2000/4 DISPAX REACTOR.RTM. of IKA.RTM. Works, Inc.
Wilmington, N.C. and APV North America, Inc. Wilmington, Mass.,
comprises a three stage dispersing module. This module may comprise
up to three rotor/stator combinations (generators), with choice of
fine, medium, coarse, and super-fine for each stage. This allows
for variance of shear rate along the direction of flow. In some
embodiments, each of the stages is operated with super-fine
generator.
[0058] In embodiments, a scaled-up version of the DISPAX.RTM.
reactor is utilized. For example, in embodiments HSD 40 comprises a
SUPER DISPAX REACTOR.RTM. DRS 2000. The HSD unit may be a DR
2000/50 unit, having a flow capacity of 125,000 liters per hour, or
a DRS 2000/50 having a flow capacity of 40,000 liters/hour. Because
residence time is increased in the DRS unit, the fluid therein is
subjected to more shear. Referring now to FIG. 2, there is
presented a longitudinal cross-section of a suitable HSD 200. HSD
200 of FIG. 2 is a dispersing device comprising three stages or
rotor-stator combinations, 220, 230, and 240. The rotor-stator
combinations may be known as generators 220, 230, 240 or stages
without limitation. Three rotor/stator sets or generators 220, 230,
and 240 are aligned in series along drive shaft 250.
[0059] First generator 220 comprises rotor 222 and stator 227.
Second generator 230 comprises rotor 223, and stator 228. Third
generator 240 comprises rotor 224 and stator 229. For each
generator the rotor is rotatably driven by input 250 and rotates
about axis 260 as indicated by arrow 265. The direction of rotation
may be opposite that shown by arrow 265 (e.g., clockwise or
counterclockwise about axis of rotation 260). Stators 227, 228, and
229 may be fixably coupled to the wall 255 of HSD 200. As mentioned
hereinabove, each rotor and stator may comprise rings of
complementarily-shaped tips, leading to several shear gaps within
each generator.
[0060] As mentioned hereinabove, each generator has a shear gap
width which is the minimum distance between the rotor and the
stator. In the embodiment of FIG. 2, first generator 220 comprises
a first shear gap 225; second generator 230 comprises a second
shear gap 235; and third generator 240 comprises a third shear gap
245. In embodiments, shear gaps 225, 235, 245 have widths in the
range of from about 0.025 mm to about 10 mm. Alternatively, the
process comprises utilization of an HSD 200 wherein the gaps 225,
235, 245 have a width in the range of from about 0.5 mm to about
2.5 mm. In certain instances the shear gap width is maintained at
about 1.5 mm. Alternatively, the width of shear gaps 225, 235, 245
are different for generators 220, 230, 240. In certain instances,
the width of shear gap 225 of first generator 220 is greater than
the width of shear gap 235 of second generator 230, which is in
turn greater than the width of shear gap 245 of third generator
240. As mentioned above, the generators of each stage may be
interchangeable, offering flexibility. HSD 200 may be configured so
that the shear rate remains the same or increases or decreases
stepwise longitudinally along the direction of the flow 260.
[0061] Generators 220, 230, and 240 may comprise a coarse, medium,
fine, and super-fine characterization, having different numbers of
complementary rings or stages on the rotors and complementary
stators. Rotors 222, 223, and 224 and stators 227, 228, and 229 may
be toothed designs. Each generator may comprise two or more sets of
complementary rotor-stator rings. In embodiments, rotors 222, 223,
and 224 comprise more than 3 sets of complementary rotor/stator
rings. In embodiments, the rotor and the stator comprise no teeth,
thus forcing the reactants to flow through the pores of a sintered
material.
[0062] HSD 40 may be a large or small scale device. In embodiments,
system 100 is used to process from less than 100 gallons per minute
to over 5000 gallons per minute. In embodiments, one or more HSD 40
processes at least 100, 500, 750, 900, 1000, 2000, 3000, 4000, 5000
gpm or more. Large scale units may produce 1000 gal/h (24
barrels/h). The inner diameter of the rotor may be any size
suitable for a desired application. In embodiments, the inner
diameter of the rotor is from about 12 cm (4 inch) to about 40 cm
(15 inch). In embodiments, the diameter of the rotor is about 6 cm
(2.4 inch). In embodiments, the outer diameter of the stator is
about 15 cm (5.9 inch). In embodiments, the diameter of the stator
is about 6.4 cm (2.5 inch). In some embodiments the rotors are 60
cm (2.4 inch) and the stators are 6.4 cm (2.5 inch) in diameter,
providing a clearance of about 4 mm. In certain embodiments, each
of three stages is operated with a super-fine generator comprising
a number of sets of complementary rotor/stator rings.
[0063] HSD 200 is configured for receiving at inlet 205 a fluid
mixture from line 13. The mixture comprises reactants, as discussed
further hereinbelow. In embodiments, the reactants comprise oil and
desulfurizing agent. In embodiments, the reactants comprise crude
oil and desulfurizing agent. In embodiments, the reactants comprise
crude oil and aqueous ammonia. In embodiments, the reactants
comprise crude oil and ammonium sulfate. In embodiments, the
reactants comprise crude oil and potassium hydroxide. In
embodiments, the reactants comprise crude oil and caustic. In
embodiments, the reactants further comprise at least one
API-adjustment gas, as discussed further hereinbelow. Feed stream
entering inlet 205 is pumped serially through generators 220, 230,
and then 240, such that product sweetened oil is produced. Product
exits HSD 200 via outlet 210 (and line 19 of FIG. 1). The rotors
222, 223, 224 of each generator rotate at high speed relative to
the fixed stators 227, 228, 229, providing a high shear rate. The
rotation of the rotors pumps fluid, such as the feed stream
entering inlet 205, outwardly through the shear gaps (and, if
present, through the spaces between the rotor teeth and the spaces
between the stator teeth), creating a localized high shear
condition. High shear forces exerted on fluid in shear gaps 225,
235, and 245 (and, when present, in the gaps between the rotor
teeth and the stator teeth) through which fluid flows process the
fluid and create desulfurized oil product. The product may comprise
an emulsion containing sweetened oil and released sulfur. The high
shear-treated stream 19 may comprise spent desulfurizing agent,
excess desulfurizing agent, altered desulfurizing agent, or some
combination thereof, as will be discussed hereinbelow. Product
exits HSD 200 via high shear outlet 210 (lines 19 of FIG. 1).
[0064] As mentioned above, in certain instances, HSD 200 comprises
a DISPAX REACTOR.RTM. of IKA.RTM. Works, Inc. Wilmington, N.C. and
APV North America, Inc. Wilmington, Mass. Several models are
available having various inlet/outlet connections, horsepower, tip
speeds, output rpm, and flow rate. Selection of the HSD will depend
on throughput selection, for example. IKA.RTM. model DR 2000/4, for
example, comprises a belt drive, 4M generator, PTFE sealing ring,
inlet flange 25.4 mm (1 inch) sanitary clamp, outlet flange 19 mm
(3/4 inch) sanitary clamp, 2HP power, output speed of 7900 rpm,
flow capacity (water) approximately 300-700 L/h (depending on
generator), a tip speed of from 9.4-41 m/s (1850 ft/min to 8070
ft/min). Scale up may be performed by using a plurality of HSDs, or
by utilizing larger HSDs. Scale-up using larger models is readily
performed, and results from larger HSD units may provide improved
efficiency in some instances relative to the efficiency of
lab-scale devices. The large scale unit may be a DISPAX.RTM.
2000/unit. For example, the DRS 2000/5 unit has an inlet size of 51
mm (2 inches) and an outlet of 38 mm (1.5 inches).
[0065] In embodiments HSD 40 or portions thereof are manufactured
from refractory/corrosion resistant materials. For example,
sintered metals, INCONEL.RTM. alloys, HASTELLOY.RTM. materials may
be used. For example, the desulfurizing agent may be very caustic,
so the rotors, stators, and/or other components of HSD 40 may be
manufactured of refractory materials (e.g. sintered metal) in
various applications.
[0066] Separation Unit(s) 10. Oil desulfurization system 100
comprises one or more separation unit(s) 10. Separation unit(s) 10
can be any type of separation vessel configured to separate phases
and/or materials of different densities. In embodiments, separation
unit(s) 10 is selected from centrifuges, decanters and filtration
units. In embodiments, separation unit 10 comprises one or more
centrifuges. In embodiments, separation unit(s) 10 comprises a
single centrifuge. In embodiments, separation unit 10 comprises one
or more filtration units. Separation unit(s) 10 may be operable
continuously, semi-continuously, or in batches. One or more
separation unit(s) 10 may be configured in series or in parallel.
For parallel operation, outlet line 19 may divide to introduce high
shear-treated product into multiple separation unit(s) 10. In
embodiments, the components separated in separation unit(s) 10 are
selected from sulfur, sweetened oil, desulfurizing agent or any
combination thereof. In the embodiment of FIG. 1, separation unit
10 comprises first separator outlet line 16, second separator
outlet line 17 and third separator outlet line 20.
[0067] Separation unit(s) 10 may include one or more of the
following components: heating and/or cooling capabilities, pressure
measurement instrumentation, temperature measurement
instrumentation, one or more injection points, and level regulator,
as are known in the art of separator design. For example, a heating
and/or cooling apparatus may comprise, for example, a heat
exchanger.
[0068] Heat Transfer Devices. Internal or external heat transfer
devices for heating the fluid to be treated are also contemplated
in variations of the system. For example, the reactants may be
preheated via any method known to one skilled in the art. Some
suitable locations for one or more such heat transfer devices are
between pump 5 and HSD 40, between HSD 40 and flow line 19, and
between flow line 17 and pump 5 when fluid in second separator
outlet 17 is recycled to HSD 40. HSD may comprise an inner shaft
which may be cooled, for example water-cooled, to partially or
completely control the temperature within the HSD. Some
non-limiting examples of such heat transfer devices are shell,
tube, plate, and coil heat exchangers, as are known in the art.
[0069] Pumps. High shear oil desulfurization system 100 may
comprise pump 5. Pump 5 is configured for either continuous or
semi-continuous operation, and may be any suitable pumping device
that is capable of providing controlled flow through HSD 40 and
system 100. In applications pump 5 provides greater than 202.65 kPa
(2 atm) pressure or greater than 303.97 kPa (3 atm) pressure. Pump
5 may be a Roper Type 1 gear pump, Roper Pump Company (Commerce
Ga.) Dayton Pressure Booster Pump Model 2P372E, Dayton Electric Co
(Niles, Ill.) is one suitable pump. Preferably, all contact parts
of the pump comprise stainless steel, for example, 316 stainless
steel. In some embodiments of the system, pump 5 is capable of
pressures greater than about 2026.5 kPa (20 atm). In addition to
pump 5, one or more additional, high pressure pumps may be included
in the system illustrated in FIG. 1. For example, a booster pump,
which may be similar to pump 5, may be included between HSD 40 and
flow line 19 for boosting the pressure into flow line 19. When oil
source 15 is an oil well, i.e., when high shear system 100 is
located near an oil well, the crude oil may be introduced at
pressure, and no pump 5 may be utilized.
[0070] High Shear Process for Producing Sweetening Oil. A process
for sweetening oil will now be described with respect to FIG. 3
which is a schematic of a method 300 of producing sweetened oil
according to an embodiment of this disclosure. Process 300
comprises providing oil and desulfurizing agent at 310; intimately
mixing the oil and desulfurizing agent to produce a high
shear-treated stream at 320; and extracting sweetened oil from the
high shear-treated stream at 330. The sulfur removal system is
operable as a closed loop. In embodiments, no distillation, no
settling tanks, and/or no external heating is required to effect
desulfurization of oil via the disclosed method.
[0071] Providing Oil to be Sweetened and Desulfurizing Agent 310.
Process 300 comprises providing oil to be sweetened and providing
desulfurizing agent(s) 310. The oil to be sweetened may be crude
oil. The oil to be treated may be introduced directly following
extraction from an oil well, and may thus be at elevated
temperature and/or pressure. In embodiments, no heating is
utilized, and the system exposed to ambient temperature. In
embodiments, oil source 15 comprises an oil well. In embodiments,
the oil to be sweetened is held in a storage unit. Thus, in
embodiments, oil source 15 comprises a storage vessel as known in
the art.
[0072] The oil to be sweetened may comprise organic and/or
inorganic forms of sulfur. For example, the oil to be sweetened may
comprise, for example, hydrogen sulfide, organic sulfides, organic
disulfides, mercaptans (also known as thiols), and aromatic ring
compounds, such as thiophene, benzothiophene and related compounds.
The sulfur in aromatic ring compounds will be herein referred to as
`thiophene sulfur.` The liquid oil extracted from oil shale as well
as that derived from tar sands is referred to as syncrude. The oil
to be sweetened may be petroleum or syncrude. The oil to be
sweetened may be refined oil or used refined oil. The oil to be
treated may also comprise chloride, mercury, vanadium, and/or other
heavy metals which may also be advantageously removed during the
disclosed sulfur removal process, as discussed further
hereinbelow.
[0073] In embodiments, providing oil to be sweetened comprises
providing one or more crude oils. Crude oils are naturally
occurring complex mixtures of hydrocarbons that typically include
small quantities of sulfur, nitrogen, and oxygen derivatives of
hydrocarbons as well as trace metals. Crude oils contain many
different hydrocarbon compounds that vary in appearance and
composition from one oil field to another. Crude oils range in
consistency from water to tar-like solids, and in color from clear
to black. An `average` crude oil contains about 84% carbon, 14%
hydrogen, 1%-3% sulfur, and less than 1% each of nitrogen, oxygen,
metals, and salts. Crude oils are generally classified as
paraffinic, naphthenic, or aromatic, based on the predominant
proportion of similar hydrocarbon molecules. Mixed-base crudes
contain varying amounts of each type of hydrocarbon. Refinery crude
base stocks usually contain mixtures of two or more different crude
oils.
[0074] Relatively simple crude oil assays are used to classify
crude oils as paraffinic, naphthenic, aromatic, or mixed. One assay
method (United States Bureau of Mines) is based on distillation,
and another method (UOP `K` factor) is based on gravity and boiling
points. More comprehensive crude assays may be utilized to estimate
the value of the crude (i.e., yield and quality of useful products)
and processing parameters. Crude oils are typically grouped
according to yield structure.
[0075] Crude oils are also defined in terms of API (American
Petroleum Institute) gravity. API gravity is an arbitrary scale
expressing the density of petroleum products. The higher the API
gravity, the lighter the crude. For example, light crude oils have
high API gravities and low specific gravities. Crude oils with low
carbon, high hydrogen, and high API gravity are usually rich in
paraffins and tend to yield greater proportions of gasoline and
light petroleum products, while those with high carbon, low
hydrogen, and low API gravities are usually rich in aromatics.
[0076] Crude oils that contain appreciable quantities of hydrogen
sulfide or other reactive sulfur compounds are referred to as
`sour.` Crude oils containing less sulfur are referred to as
`sweet.` A notable exceptions to this rule are West Texas crude
oils, which are always considered `sour` regardless of their
hydrogen sulfide content, and Arabian high-sulfur crudes, which are
not considered `sour` because the sulfur compounds therein are not
highly reactive. Providing crude oil at 310 may comprise providing
one or more selected from sour crude oils. The sour crude oils may
be low API crude oils, high API crude oils, medium API crude oils,
paraffinic crude oils, naphthenic crude oils, aromatic crude oils,
mixed crude oils, or any combination thereof. Table 1 shows typical
characteristics, properties, and gasoline potential of various
crude oils. In embodiments, providing oil to be sweetened at 310
comprises providing one or more crude oil similar to those
presented in Table 1.
TABLE-US-00001 TABLE 1 Typical Approximate Characteristics,
Properties and Gasoline Potential of Various Crude Oils* Sulfur
Napht. Paraffins Aromatics Naphthenes (wt. ~API Yield Octane #
Source (vol. %) (vol. %) (vol. %) %) Gravity (vol. %) (est.)
Nigerian- 37 9 54 0.2 36 28 60 Light Saudi- 63 19 18 2 34 22 40
Light Saudi- 60 15 25 2.1 28 23 35 Heavy Venezuela- 35 12 53 2.3 30
2 60 Heavy Venezuela- 52 14 34 1.5 24 18 50 Light USA- -- -- -- 0.4
40 -- -- Midcont. Sweet USA-W. 46 22 32 1.9 32 33 55 Texas Sour
North Sea- 50 16 34 0.4 37 31 50 Brent *(representative average
values)
[0077] The oil to be sweetened may comprise about 5, 4, 3, 2 or 1
weight percent sulfur. In embodiments, the oil to be sweetened
comprises from about 0.2 to about 20 ppm sulfur. In embodiments,
the oil to be sweetened comprises from about 0.2 to about 10 ppm
sulfur. In embodiments, the oil to be sweetened comprises from
about 5 to about 10 ppm sulfur. In embodiments, the oil to be
sweetened comprises from about 0.1 to about 5 ppm thiophene
sulfur.
[0078] Providing oil to be sweetened and desulfurizing agent at 310
comprises providing at least one desulfurizing agent. In
embodiments, providing oil and desulfurizing agent comprises
providing a 50:50 volume mixture of oil and desulfurizing agent. In
embodiments, the desulfurizing agent is a base. The desulfurizing
agent may be caustic. In embodiments, the desulfurizing agent is
selected from the group consisting of ammonia, sodium hydroxide,
potassium hydroxide, ammonium sulfate, calcium carbonate, hydrogen,
hydrogen peroxide, monoethanolamine (MEA), diglycolamine (DGA),
diethanolamine (DEA), diisopropanolamine (DIPA) and
methyldiethanolamine (MDEA). In embodiments, the desulfurizing
agent is aqueous ammonia. In embodiments, the desulfurizing agent
is 28% aqueous ammonia (28% NH.sub.4OH). In embodiments, the
desulfurizing agent comprises an inorganic salt. In embodiments,
the desulfurizing agent comprises calcium carbonate. In
embodiments, the desulfurizing agent comprises ammonium sulfate.
Ammonium sulfate may be formed within HSD 40 (when aqueous ammonia
is initially introduced as desulfurizing agent into HSD 40) and
recycled for use as desulfurizing agent. Alternatively, ammonium
sulfate may be purchased and introduced into HSD 40. Alternatively,
ammonium sulfate may be produced on site, for example, from dry
ammonium sulfate and water.
[0079] Intimately Mixing Oil and Desulfurizing Agent 320. Process
300 comprises intimately mixing the oil to be sweetened and the
desulfurizing agent(s) at 320. Intimately mixing may comprise
subjecting the oil to be sweetened and the desulfurizing agent(s)
to high shear to produce a high shear-treated stream. In
embodiments, subjecting the oil to be sweetened and the
desulfurizing agent(s) to high shear comprises subjecting to a
shear rate of at least 10,000 s.sup.-1, at least 20,000 s.sup.-1,
at least 30,000 s.sup.-1, or higher, as further discussed
hereinbelow. In embodiments, intimately mixing the oil and
desulfurizing agent 320 comprises introducing the oil to be
sweetened (e.g., via lines 21 and 13) and the desulfurizing
agent(s) (e.g., via line 22) into a HSD 40, as indicated in FIG.
1.
[0080] Referring now to FIG. 1, intimately mixing the oil and
desulfurizing agent(s) 320 may comprise introducing the oil to be
sweetened from oil source 15 into HSD 40. Pump 5 is used to pump
the oil into HSD 40. The desulfurizing agent(s) may be introduced
into line 13 via line 22 or elsewhere throughout system 100. For
example, fresh or makeup ammonia may be introduced via line 22. In
embodiments, gas is introduced into HSD 40 along with the oil to be
sweetened and the desulfurizing agent(s). For example, gas may be
introduced into HSD 40 via line 22, via an additional inlet line,
may be introduced directly into HSD 40, or may be present in the
oil introduced from oil source 15. When line 22 is utilized for the
introduction of desulfurizing agent(s), a second line may introduce
gas into line 13.
[0081] The introduction of gas into HSD 40 along with desulfurizing
agent may be utilized to alter the API of the resulting sweetened
crude oil. Generally, refining of crude oil produces significant
amounts of refinery-related gas. Generally 5% or so of the crude
oil is converted to various gases during refinery operations). Such
gases are typically used as fuel or flared. The use of such gas for
API enhancement may be desirable over the flaring of such gas,
especially in view of progressively tighter emissions restrictions.
Additionally, passing the API adjustment gas through the HSD along
with the desulfurizing agent may serve to clean the gas (i.e.
remove sulfur (such as hydrogen sulfide) therefrom). A significant
portion of the gas may be consumed in reactions in the HSD. Any
remaining gas may be recycled to HSD 40, flared, or used for
fuel.
[0082] The method may serve to alter the API gravity and/or
stabilize the crude oil, by reducing volatile components therein,
and also sweeten the oil by removal of sulfur therefrom. It is
noted that even in the absence of gas addition, intimately mixing
the oil to be sweetened and the desulfurizing agent(s) may
effectively raise the API gravity. For example, removal of sulfur
from crude oil comprising thiophene compounds may result in
sweetened oil having a higher API gravity than the sour crude oil
introduced thereto.
[0083] The refinery-related gas may comprise various amounts of
carbon dioxide, carbon monoxide, hydrogen, methane, ethane, and/or
hydrogen sulfide, for example. In embodiments, the API adjustment
gas is or comprises carbon dioxide. Additionally, crude oil may be
extracted from the earth in conjunction with associated gas.
Associated gas is gas found dissolved in crude oil at the high
pressures existing in a reservoir, or gas present as a gas cap over
the oil. Associated gas comprises natural gas. Unassociated gas may
also be available. The phrase `unassociated gas` herein refers to
gas obtained in a reservoir in the absence of oil, as known in the
art. The gas introduced into HSD along with desulfurizing agent may
be selected from, but is not limited to: FCC offgas, pyrolysis gas,
associated gas, hydrodesulfurization offgas, catalytic cracker
offgas, thermal cracker offgas, unassociated gas, and combinations
thereof. For example, regeneration of FCC catalyst in a refinery
may produce significant quantities of CO and/or CO.sub.2, which may
be introduced into the HSD along with the desulfurizing agent(s).
The gas may be selected from associated gas, unassociated gas,
refinery-related gas, methane, ethane, carbon monoxide, carbon
dioxide, hydrogen and combinations thereof. In embodiments, crude
oil extracted from the earth with associated gas is intimately
mixed via HSD 40 (desirably before pressure reduction) with
desulfurizing agent to adjust the stability and/or the API gravity
thereof and remove sulfur therefrom. In embodiments, crude oil
extracted from the earth (with or without associated gas) is
intimately mixed with unassociated gas and desulfurizing agent(s)
via HSD 40 to adjust the stability/API gravity thereof and remove
sulfur therefrom. The removal of sulfur within HSD 40 will enhance
interaction of the gas with the crude oil, and a substantial
portion of the gas introduced into HSD 40 may be consumed. The
presence, in the crude oil, of vanadium and other metals having
catalytic properties, may enhance the reaction of the crude oil
with the API-adjustment gas.
[0084] Referring now to FIG. 1, when present, pump 5 may be
operated to pump the oil to be sweetened through line 13, and to
build pressure and feed HSD 40, providing a controlled flow
throughout high shear (HSD) 40 and high shear system 100. In some
embodiments, pump 5 increases the pressure of the HSD inlet stream
in line 13 to greater than 200 kPa (2 atm) or greater than about
300 kPa (3 atmospheres). In this way, high shear system 100 may
combine high shear with pressure to enhance production of sweetened
oil. As mentioned above, when the crude oil is sweetened at the
wellhead or well site, the oil may have suitable pressure as
extracted from the ground, in which case, pump 5 is not
utilized.
[0085] Within high shear device 40, desulfurizing agent(s) and
optionally API-adjustment gas are intimately mixed with the oil to
be sweetened. The temperature, shear rate and/or residence time
within HSD 40 may be controlled to effect desired sulfur removal.
For example, the operating parameters may be selected/adjusted to
produce sweetened oil having less than a desired sulfur content.
The desired sulfur content may be less than 2 weight percent
sulfur, less than 1.5 weight percent sulfur, less than 1.0 weight
percent sulfur, less than 0.75 weight percent sulfur, less than 0.5
weight percent sulfur, or less than about 0.25 weight percent
sulfur.
[0086] Subjecting the oil and desulfurizing agent (and optionally
API adjustment gas) to high shear may provide an emulsion or
dispersion comprising droplets of the desulfurizing agent or oil or
bubbles of the API adjustment gas. In embodiments, an emulsion or
dispersion comprising nanodroplets and/or microdroplets of liquid
and/or nanobubbles and/or microbubbles of the API-adjustment gas is
formed. In embodiments, the droplets in the emulsion and/or the
bubbles in the dispersion have an average diameter of less than or
about 5, 4, 3, 2 or 1 .mu.m. In embodiments, the droplets in the
emulsion and/or the bubbles in the dispersion have an average
particle diameter in the nanometer range, the micron range, or the
submicron range.
[0087] Within HSD 40, the contents are subjected to high shear. In
an exemplary embodiment, the high shear device comprises a
commercial disperser such as IKA.RTM. model DR 2000/4, a high
shear, three stage dispersing device configured with three rotors
in combination with stators, aligned in series, as described above.
The disperser is used to subject the contents to high shear. The
rotor/stator sets may be configured as illustrated in FIG. 2, for
example. In such an embodiment, the feed enters the high shear
device via line 13 and enter a first stage rotor/stator combination
having circumferentially spaced first stage shear openings. The
coarse mixture exiting the first stage enters the second
rotor/stator stage, which has second stage shear openings. The
mixture emerging from the second stage enters the third stage
rotor/stator combination having third stage shear openings. The
rotors and stators of the generators may have circumferentially
spaced complementarily-shaped rings. A high shear-treated stream
exits the high shear device via line 19. In some embodiments, the
shear rate increases stepwise longitudinally along the direction of
the flow 260, or going from an inner set of rings of one generator
to an outer set of rings of the same generator. In other
embodiments, the shear rate decreases stepwise longitudinally along
the direction of the flow, 260, or going from an inner set of rings
of one generator to an outer set of rings of the same generator
(outward from axis 200). For example, in some embodiments, the
shear rate in the first rotor/stator stage is greater than the
shear rate in subsequent stage(s). For example, in some
embodiments, the shear rate in the first rotor/stator stage is
greater than or less than the shear rate in a subsequent stage(s).
In other embodiments, the shear rate is substantially constant
along the direction of the flow, with the stage or stages being the
same. If HSD 40 includes a PTFE seal, for example, the seal may be
cooled using any suitable technique that is known in the art. The
HSD 40 may comprise a shaft in the center which may be used to
control the temperature within HSD 40. For example, the
desulfurizing agent flowing in line 22 may be used to cool the seal
and in so doing be preheated prior to entering the high shear
device.
[0088] The rotor(s) of HSD 40 may be set to rotate at a speed
commensurate with the diameter of the rotor and the desired tip
speed. As described above, the HSD (e.g., colloid mill or toothed
rim disperser) has either a fixed clearance between the stator and
rotor or has adjustable clearance.
[0089] In some embodiments, HSD 40 delivers at least 300 L/h at a
nominal tip speed of at least 22 m/s (4500 ft/min), 40 m/s (7900
ft/min), and which may exceed 225 m/s (45,000 ft/min) or greater.
The power consumption may be about 1.5 kW or higher as desired.
Although measurement of instantaneous temperature and pressure at
the tip of a rotating shear unit or revolving element in HSD 40 is
difficult, it is estimated that the localized temperature seen by
the intimately mixed reactants may be in excess of 500.degree. C.
and at pressures in excess of 500 kg/cm.sup.2 under high shear
conditions.
[0090] Conditions of temperature, pressure, space velocity,
API-adjustment gas composition, and/or ratio of desulfurizing agent
to oil to be sweetened may be adjusted to effect a desired sulfur
removal. Such parameters may be adjusted as the composition of the
crude oil to be treated varies. In some embodiments, the operating
temperature and pressure are determined by the temperature and
pressure at which the crude oil exits the wellhead. The residence
time within HSD 40 is typically low. For example, the residence
time can be in the millisecond range, can be about 10, 20, 30, 40,
50, 60, 70, 80, 90 or about 100 milliseconds, can be about 100,
200, 300, 400, 500, 600, 700, 800, or about 900 milliseconds, can
be in the range of seconds, or can be any range thereamong.
[0091] As mentioned above, intimately mixing the crude oil with the
desulfurizing agent(s) may comprise running the crude oil through
one or more HSDs 40. Intimately mixing the crude oil with the
desulfurizing agent(s) may comprise running the crude oil through
two or more HSDs 40, in series or in parallel. Intimately mixing
the crude oil with the desulfurizing agent(s) may comprise running
the crude oil through three or more HSDs 40, in series and/or in
parallel. Additional API-adjustment gas and/or desulfurizing
agent(s) may be introduced into each subsequent HSD.
[0092] Without wishing to be limited by theory, when aqueous
ammonia and/or ammonium sulfate are introduced into HSD 40 as
desulfurizing agent(s), ammonium sulfate present within HSD 40 will
repetitively release sulfur and extract further sulfur from the
oil. The presence of elemental sulfur will effect removal of
chloride, mercury, vanadium, and other heavy metals which may have
been present in the oil to be sweetened. Thus, sulfur removal may
be combined with chloride and/or heavy metal removal via the
disclosed system and method.
[0093] Without wishing to be limited by theory, it is believed that
the conditions within HSD 40 force reactions that would otherwise
not be thermodynamically favorable. In embodiments, the
desulfurizing agent(s) introduced into HSD 40 comprises aqueous
ammonia or ammonium sulfate. The ammonium sulfate formed within HSD
40 or introduced as desulfurizing agent (e.g. introduced into HSD
40 via line 22 or recycled from separation unit(s) 10, as discussed
further hereinbelow) sequentially removes sulfur from the oil. The
ammonium sulfate may thus be considered a catalyst in the
desulfurization, consecutively removing sulfur from the oil,
releasing elemental sulfur (due to the shear/pressure), and
extracting subsequent sulfur molecules from the oil.
[0094] Extracting Sweetened Oil 330. High shear sulfur removal
method 300 further comprises extracting sweetened oil at 330.
Extracting sweetened oil 330 comprises separating sweetened oil
from high shear-treated stream 19. During intimately mixing 320,
the desulfurizing agent may be converted to a new form. For
example, when fresh aqueous ammonia is introduced into HSD 40 along
with oil to be sweetened, ammonium sulfate will form within HSD 40.
Extracting sweetened oil may thus comprise separating sweetened oil
from sulfur and desulfurizing agent(s), which may comprise the same
desulfurizing agent originally introduced into HSD 40 or may
comprise a desulfurizing agent formed within HSD 40 (e.g., ammonium
sulfate). In embodiments, desulfurizing agent(s) are extracted from
separation unit(s) 10 via second separator outlet 17; sweetened oil
is removed from separation unit(s) 10 via first separator outlet
16; and (solid) sulfur is removed from separation unit(s) 10 via
third separator outlet 20. As mentioned above, in embodiments,
API-adjustment gas is introduced into HSD 40 along with
desulfurizing agent(s) and oil. Any unreacted gas or produced gas
may be removed upstream of separation unit(s) 10 or removed from
separation unit(s) 10. Unreacted or product gas may be recycled as
desired to HSD 40 or to a different HSD, or used as fuel or
flared.
[0095] As discussed hereinabove, separation unit(s) may be selected
from centrifuges, filtration devices (e.g. filter press),
decanters, and combinations thereof. In embodiments, separation
unit(s) 10 is one or more centrifuges.
[0096] In embodiments, the desulfurizing agent(s) introduced into
HSD 40 or formed therein act as a catalyst in the sulfur removal
process. In such instances, for example when desulfurizing agent
comprising aqueous ammonia is introduced into HSD 40 (and ammonium
sulfate is formed within HSD 40) or when ammonium sulfate is
introduced into HSD 40, desulfurizing agent separated from high
shear-treated stream 19 may be recycled from separation unit(s) 10
to HSD 40 by fluidly connecting second outlet 17 with line 22, line
21, or line 13, whereby a portion of the contents of second outlet
line 17 may be recycled to HSD 40, or by introducing the contents
of line 17 (or a portion thereof) directly into HSD 40. The
separated desulfurizing agent may comprise the same desulfurizing
agent introduced into HSD 40 (e.g., unreacted aqueous ammonia or
ammonium sulfate introduced into HSD 40) or desulfurizing agent
formed within HSD 40 (e.g., ammonium sulfate formed within HSD 40
due to introduction of aqueous ammonia into HSD 40). Recycle of
desulfurizing agent(s) may be desirable, to reduce the amount of
desulfurizing agent utilized in the desulfurization. For example,
initially, aqueous ammonia may be introduced into HSD 40 via line
22. Within HSD 40, ammonium sulfate is formed, which repetitively
extracts sulfur from the oil to be sweetened. The ammonium sulfate
is separated from the sweetened oil product (which exits separation
unit(s) 10 via first separator outlet 16) and solid removed sulfur
(which exits separation unit(s) 10 via third separator outlet 20)
and some or all of the ammonium sulfate is recycled to HSD 40 via
second separator outlet 17. In such instances, introduction of
fresh aqueous ammonia may be terminated when sufficient ammonium
sulfate has been produced and is available for recycle to HSD 40.
This is desirable, for example, as aqueous ammonia must be handled
carefully, and because, especially for large scale operation, cost
can be significantly reduced by utilizing recycled material rather
than by using massive volumes of fresh desulfurizing agent. Should
ammonium sulfate be desirable as sale product or for use elsewhere,
ammonium sulfate may not be recycled. Alternatively or
additionally, ammonium sulfate may be recycled through system 100
and sulfur removed primarily as elemental sulfur (e.g. sulfur
crystals).
[0097] In other embodiments, the desulfurizing agent(s) is spent
during operation, and altered desulfurizing agent is not recycled,
but is removed from system 100 via second outlet 17. For example,
when caustic is utilized as desulfurizing agent, NaCl may be
formed, which does not reverse and extract further sulfur from the
oil. In such instances, fresh caustic will need to be continually
introduced as necessary into HSD 40 during operation.
[0098] Product Sweetened Oil. The sweetened oil removed from
separation unit(s) 10 comprises oil having a lower sulfur content
than the oil to be sweetened. The sweetened oil may have a sulfur
content of less than 2 weight percent sulfur, less than 1.5 weight
percent sulfur, less than 1.0 weight percent sulfur, less than 0.75
weight percent sulfur, less than 0.5 weight percent sulfur, or less
than about 0.25 weight percent sulfur. In embodiments, the sulfur
content of the sweetened oil is less than 90, 80, 70, 60, 50, 40,
30, 20, or 10% of the sulfur content of the oil to be sweetened.
For example, the sweetened oil may comprise 10% of the sulfur
content of the crude oil introduced into HSD 40.
[0099] In embodiments, chloride is removed during desulfurization.
Chloride may be removed as sodium chloride or ammonium chloride,
for example. In embodiments, the chloride content of the sweetened
oil is less than about 50%, 40%, 30%, 20%, 15%, or less than about
10% of the chloride content of the oil to be sweetened.
[0100] As mentioned above, removal of sulfur from the oil may
beneficially alter the API gravity of the crude oil. Additionally,
introduction of gas into HSD 40 along with oil to be sweetened and
desulfurizing agent(s) may further enhance the API gravity and/or
stability of the oil. In embodiments, the API of the sweetened oil
product is at least or about 1.25, 1.5 or 2 times the API of the
oil to be sweetened. In embodiments, the API of a crude oil is
increased from about 15 to about 30, from about 5 to about 20, or
from about 10 to about 20 via the disclosed method.
[0101] The sulfur removed from separation unit(s) 10 via third
outlet 20 comprises solid sulfur, and will generally appear yellow.
The sulfur may be present as regular sulfur or poly sulfur. Various
allotropes of sulfur may be present in the removed sulfur, for
example, S8, S7, S6 or combinations thereof. When desulfurizing
agent comprises ammonia, sulfur is also removed as ammonium
sulfate. The sulfur may be removed as a filter cake, as a slurry,
or as a dry product, for example, from a centrifuge.
[0102] Multiple Pass Operation. In the embodiment shown in FIG. 1,
the system is configured for single pass operation. The output of
HSD 40 may be run through a subsequent HSD. In some embodiments, it
may be desirable to pass the contents of flow line 19, or a
fraction thereof, through HSD 40 during a second pass. In this
case, at least a portion of the contents of flow line 19 may be
recycled from flow line 19 and optionally pumped by pump 5 into
line 13 and thence into HSD 40. Additional reactants (e.g.,
API-adjustment gas and/or desulfurizing agent(s)) may be injected
via line 22 into line 13, or may be added directly into the HSD. In
other embodiments, product in outlet line 19 is fed into a second
HSD prior to separation unit(s) 10. Due to the rapidity of the
sulfur removal witnessed in the experiments performed to date, it
appears that multiple pass operation may not be necessary or
desirable.
[0103] Multiple HSDs. In some embodiments, two or more HSDs like
HSD 40, or configured differently, are aligned in series, and are
used to promote further reaction. In embodiments, the reactants
pass through multiple HSDs 40 in serial or parallel flow. In
embodiments, a second HSD may be positioned downstream of
separation unit(s) 10, whereby the sweetened oil exiting separation
unit(s) 10 via first outlet 16 may be introduced into a subsequent
HSD for removal of remaining sulfur therefrom. When multiple HSDs
40 are operated in series, additional reactants may be injected
into the inlet feedstream of each HSD. For example, additional API
adjustment gas and/or desulfurizing agent(s) may be introduced into
a second or subsequent HSD 40. In some embodiments, multiple HSDs
40 are operated in parallel, and the outlet products therefrom are
introduced into one or more flow lines 19.
[0104] Features. The rate of chemical reactions involving liquids,
gases and solids depend on time of contact, temperature, and
pressure. In cases where it is desirable to react two or more raw
materials of different phases or immiscible materials, one of the
limiting factors controlling the rate of reaction involves the
contact time of the reactants. When reaction rates are accelerated,
residence times may be decreased, thereby increasing obtainable
throughput.
[0105] The intimate contacting of reactants provided by the HSDs
may allow and/or result in faster and/or more complete sulfur
removal than simple mixing. In embodiments, use of the disclosed
process comprising reactant mixing via external HSD allows use of
reduced quantities of catalyst (e.g. ammonium sulfate) than
conventional configurations and methods, and/or increases sulfur
removal.
[0106] Without wishing to be limited to a particular theory, it is
believed that the level or degree of high shear mixing may be
sufficient to increase rates of mass transfer and also produce
localized non-ideal conditions (in terms of thermodynamics) that
enable reactions to occur that would not otherwise be expected to
occur based on Gibbs free energy predictions and/or increase the
rate or extent of expected reactions. For example, in conventional
mixing of crude oil with aqueous ammonia, ammonium sulfate may
form, but the catalytic effect of the ammonium sulfate and
successive removal of additional sulfur from the oil to be
sweetened by the ammonium sulfate due to the release of the sulfur
at the high pressure/shear encountered in the HSD would not be
expected to occur. Localized non ideal conditions are believed to
occur within the HSD resulting in increased temperatures and
pressures with the most significant increase believed to be in
localized pressures. The increases in pressure and temperature
within the HSD are instantaneous and localized and quickly revert
back to bulk or average system conditions once exiting the HSD.
Without wishing to be limited by theory, in some cases, the HSD may
induce cavitation of sufficient intensity to dissociate one or more
of the reactants into free radicals, which may intensify a chemical
reaction or allow a reaction to take place at less stringent
conditions than might otherwise be required. Cavitation may also
increase rates of transport processes by producing local turbulence
and liquid micro-circulation (acoustic streaming). An overview of
the application of cavitation phenomenon in chemical/physical
processing applications is provided by Gogate et al., "Cavitation:
A technology on the horizon," Current Science 91 (No. 1): 35-46
(2006). The HSD of certain embodiments of the present system and
methods may induce cavitation whereby one or more reactant is
dissociated into free radicals, which then react. In embodiments,
the extreme pressure at the tips of the rotors/stators leads to
liquid phase reaction, and no cavitation is involved.
[0107] Various dimensions, sizes, quantities, volumes, rates, and
other numerical parameters and numbers have been used for purposes
of illustration and exemplification of the principles of the
invention, and are not intended to limit the invention to the
numerical parameters and numbers illustrated, described or
otherwise stated herein. Likewise, unless specifically stated, the
order of steps is not considered critical. The different teachings
of the embodiments discussed herein may be employed separately or
in any suitable combination to produce desired results.
[0108] While preferred embodiments of the invention have been shown
and described, modifications thereof can be made by one skilled in
the art without departing from the spirit and teachings of the
invention. The embodiments described herein are exemplary only, and
are not intended to be limiting. Many variations and modifications
of the invention disclosed herein are possible and are within the
scope of the invention. Where numerical ranges or limitations are
expressly stated, such express ranges or limitations should be
understood to include iterative ranges or limitations of like
magnitude falling within the expressly stated ranges or limitations
(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater
than 0.10 includes 0.11, 0.12, 0.13, and so forth). Use of the term
`optionally` with respect to any element of a claim is intended to
mean that the subject element is required, or alternatively, is not
required. Both alternatives are intended to be within the scope of
the claim. Use of broader terms such as comprises, includes,
having, etc. should be understood to provide support for narrower
terms such as consisting of, consisting essentially of, comprised
substantially of, and the like.
[0109] Accordingly, the scope of protection is not limited by the
description set out above but is only limited by the claims which
follow, that scope including all equivalents of the subject matter
of the claims. Each and every claim is incorporated into the
specification as an embodiment of the present invention. Thus, the
claims are a further description and are an addition to the
preferred embodiments of the present invention. The disclosures of
all patents, patent applications, and publications cited herein are
hereby incorporated by reference, to the extent they provide
exemplary, procedural or other details supplementary to those set
forth herein.
* * * * *