Note: Descriptions are shown in the official language in which they were submitted.
-
l 159788
01
--1--
UPGRADING HYDROCARBONACEOUS OILS
WITH AN AQUEOUS ~IQUID
05
BACKGROUND OF THE INVENTION
The present invention concerns a process for
upgrading hydrocarbonaceous oils. More specifically, the
invention concerns a process for upgrading heavy oils by
contacting the oils with free oxygen and liquid phase
water at an elevated temperature.
Heavy petroleum fractions such as residuals and
heavy crude oils can be used as low grade commercial fuels
or may be converted by thermal and catalytic conversion
processes into more valuable, lighter hydrocarbons, parti-
cularly gasoline. Heavy crudes and heavy oil fractionsare oten contaminated with substantial ccncentrations of
detrimental materials. Common contaminants are organic
nitrogen and sulfur compounds, metals, particularly nickel
and vanadium, nondistillable, heat-sensitive coke precur-
sors, such as asphaltenes, and the like. When heavy oilsare burned directly as fuel, combustion of the nitrogen
and sulfur compounds results in formation of objectionable
pollutants, nitrogen oxides and sulfur oxides. When heavy
25 oils are upgraded by conven~ional catalytic conversions,
the presence o~ the nitrogen and sulfur compounds, and
particularly the presence o the metals, results in rapid
deactivation of catalysts, and causes the upgrading of
residual oils to be undesirably expensive. Conventional
methods for upgrading heavy oil fractions to provide more
valuable hydrocarbons often consume substantial amounts of
hydrogen. The cost of hydrogsn consumed is an economic
drawback when hydroprocessing is employed for the upgrad-
ing. When heavy crudes and oil fractions are subjected to
conventional pyrolysis-type coking (e.g., delayed or fluid
coking) at temperatures of 350C to 500C, large concen-
trations of heat-sensitive, coke-forming materials, such
as asphaltenes, can result in relatively low yields of the
more valuable primary pr~oduct, distillates, and relatively
high yields of the less valuable by-product, coke. The
. .
1 159788
presence of undesirably large concentrations of contaminants in coke derived
by conventional coking of heavy oils detracts from the value of coke as a
by-product. This is particularly true for sulfur. The quality of coke
obtained from heavy oil high in contaminants may thus make it unsuitable for
some uses, e.g., electrodes, because of poor specifications of such
properties as coefficient of thermal expansion, electrical resistivity and
sulfur content.
A general discussion of the wet air oxidation technology, is to be
found in Mechanical Engineering, December 1979, page 30. A discussion of
the regeneration of active carbon after use in waste water treating, by
means of wet air oxidation, i9 to be found in the AICHE Symposium Series,
Vol. 76, No. 192, (Recent Advances in Separation Technology - II), page 51
(AICHF, 1980).
A process for removing pyritic sulfur from coal by treatment with
water and air at elevated temperature and pressure to convert the pyritic
sulfur to water-soluble ferrous and ferric sulfate is disclosed in United
States Patent No. 3,824,084. Use of silicates and an oxidizing agent (such
;~ as air, oxygen, hydrogen, peroxide, alkali metal sulfides, alkaline or metal
sulfides) or a reducing agent (such as H2, C0, K2, S204, NaS204, and alkali
metal polythionates) in an aqueous medium to desulfurize coal is disclosed
in United States Patents No. 4,174,953 and No. 4,197,090.
Use of wet air oxidation to provide heat energy in the form of
steam, as by wet oxidation of coal, is disclosed in United States Patents
No. 4,211,174, No. 4,100,730, and 4,013,560.
Use of copper or silver ions to catalyze wet air oxidation of
organic material in waste water is disclosed in United States Patent
;~ No. 3,912,626.
Treatment of papermill waste sludges to convert organic components
to innocuous oxidation products and to provide for recovery of inorganic
i
filter materials for reuse is disclosed in United States Patent No. 3,876,497.
--2--
1 159788
01 _3_
Essentially complete oxidation of solid or
liquid combustible materials which are difficult to sus-
pend in water, such as diesel fuel and nitroglycerine by
direct injection into a wet air oxidation reactor is dis-
closed in U.S. Patent No. 4,174,280.
None of the disclosures concerning wet air oxi-
dation is concerned with upgrading of hydrocarbonaceous
materials. Hydrocarbonaceous oils which are utilized in
the disclosed wet air oxidation processes are simply
essentially completely consumed to form highly oxidized
materials, primarily carbon dioxide, water and the like.
SUMMARY OF THE INVENTION
..
The present invention concerns a process for
upgrading a hydrocarbonaceous oil which comprises con-
tacting the oil with free oxygen in the presence of an
aqueous liquid at a temperature above about 175C and a
pres~ure sufficient to maintain the aqueous liquid at
least partially in a liquid phase.
I have found that surprising improvements in
several properties of a heavy hydrocarbonaceous oil can be
advantageously obtained by contacting the oil with free
oxygen and liquid phase water at an elevated temperature.
The amounts of contaminants, such as metals, nitrogen and
sulfur, in the oil can be substantially decreased. The
viscosity of the oil can be substantially decreased. When
the temperature is maintained generally below about 300C,
the amount of nondistillable, coke-forming constituents of
the oils, such as asphaltenes, can be substantially
decreased. ~he process of present invention also permits
the viscosity of heavy oils to be substantially decreased.
The present process can advantageously be performed at a
temperature much lower than used in conventional heavy oil
upgrading systems.
In one embodiment, the present invention con-
cerns a process for producing coke from a hydroc~rbona-
~ ceous oil, which comprises forming coke by contacting the
;l 40 oil with free oxygen in the presence of an aqueous liquid
~ at a temperature of at least 300C and a pressure
,
' ,~:
`` 1 159788
01 _4_
sufficient to maintain the aqueous liquid at least
partially in the liquid phase.
I have found that high-quality coke can be
formed from a heavy hydrocarbonaceous oil by contact with
liquid phase water and free oxygen at elevated temperature
and pressure. The amounts of such contaminants as metals
and sulfur in the resulting coke are advantageously low,
and a desirable, low yield of coke, relative to distill-
able hydrocarbons, is obtained. Advantageously, the coke
formation can be carried out in a continuous manner, eli-
minating the need for removal of coke from drums, as is
done in delayed coking. Heat requirements for the present
process can be provided completely by oxidation of heavy
oil in the system.
DESCRIPTION OF THE DRAWING
The attached drawing is a schematic representa-
0 tion of preferred embodiments of the present invention.
In an embodiment for mild hydrocarbon upgrading,
there is shown a wet air oxidation reactor l. Aqueous
liquid is introduced into the system through a conduit
3. A feed stream of hydrocarbonaceous oil to be upgraded
25 ~ is introduced to the system through a conduit 5 and is
charged to the reactor l through a diesel injector (not
shown~ at a rate of one part (by volume) of oil per four
parts of aqueous liquid. Free oxygen-containing gas is
introduced into the system through a conduit 7 and is
mixed with the aqueous liquid in the conduit 3. The
~ water-oxygen mixture is passed into the reactor l. In the
;; ~ reactor the oil-water-oxygen mixture is maintained at
suitable reaction conditions including an appropriate
elevated temperature such as 204C and a pressure suffi-
cient to maintain the aqueous phase as a liquid such as 50
atmospheres. The mixture flows upwardly through the reac-
tor and is removed from the top of the reactor through a
conduit 9. The mixture is then cooled in a heat exchanger
ll, passed through a pressure reducing valve 13, and
charged to gas separator vessel 15, in which the gases in
:
l 159788
01 -5-
the mixture are separated from the aqueous and hydrocar-
bonaceous liquids. The gases are removed from the top of
the separator vessel 15 and passed out of the system
through a conduit 17. The mixture of liquid aqueous and
hydrocarbonaceous phases is withdrawn from the vessel 15
and passed through a conduit 19 into a phase separator,
such as a settling vessel 21. The lighter oil phase rises
to the top of the vessel 21 and is withdrawn from the
vessel and recovered by means of a conduit 23. Aqueous
liquid settles to the bottom of the vessel 21 and is with-
drawn through a conduit 25.
In a coking embodiment, aqueous liquid, which
may include fresh water, recycle water, or both, is intro-
duced into the system through a conduit 3. A feed stream
of heavy hydrocarbonaceous oil to be converted is intro-
duced to the system through a conduit 5 and is mixed with
the aqueous phase in the conduit 3. Free oxygen-contain-
ing gas i5 introduced into the system through a conduit 7
and is passed into the lower portion of the reactor 1.
The oil-water mixture in the conduit 3 is passed into the
reactor 1 above the oxygen inlet. In the reactor, the
; mixture is maintained at suitable reaction conditions
including an elevated temperature above 300C, such as
about 375C, and a pressure sufficient to maintain the
aqueous phase as a liquid such as 70 atmospheres. The
liquids and gases flow upwardly through the reactor and
are removed from the top of the reactor through a con-
duit 9. The mixture is then cooled in a heat
exchanger 11, and is passed through a pressure reducing
. ,
valve 13. The mixture is then charged to a gas separator
vessel 15, in which gases in the mixture are separated
from the liquids. Gases are removed from the top of the
gas separator vessel and withdrawn from the system through
a conduit 17. The mixture of aqueous and hydrocarbona-
ceous liquid phases is then passed from the vessel 15
through a conduit 19 into phase separation means, such as
a settling vessel 21. The generally lighter oil phase
rises to the top of the vessel 21 and is withdrawn by
:
`~:
~' :
1 15~788
Ol -6-
means of a conduit 23. Aqueous liquid settles to the
bottom of the vessel 21 and is withdrawn through a con-
; 05 duit 25. The hydrocarbonaceous liquid is passed from the
conduit 23 into a fractionator vessel 27. Lower-boiling,
more valuable product hydrocarbons are vaporized, with-
drawn overhead through a conduit 29, and recovered.
Higher-boiling, less valuable components of the oil are
withdrawn from the bottom of the fractionator and recycled
to the feed conduit 3 by way of a conduit 31. A reboiling
slip stream from the liquid effluent in the conduit 31 is
removed into a conduit 33, heated in a furnace 35, and
returned to the fractionator through a conduit 37.
Referring again to the reactor vessel 1, reactions occur
in the vessel which form solid coke particles. The coke
particles sink to the bottom of the vessel, and are
withdrawn as a slurry in aqueous liquid through a conduit
39. Coke is separated from most of the aqueous liquid in
a centrifuge 41 and is withdrawn from the system as a
concentrated aqueous slurry by way of a conduit 43.
Aqueous liquid is withdrawn from the centrifuge through a
conduit 45. The aqueous streams in conduits 25 and 45
may, if desired, be recycled directly to the reactor 1, or
may be mixed with fresh water in the conduit 5 or hydro-
carbon feed in the conduit 3. The water recycle streams
may be treated, as for removal of solids, mineral salts,
and the like (by means not shown) prior to recycle, if
desired. Various conventional elements necessary for
carrying out the embodiment depicted in the drawing, such
~; as control means, pumping means, compressing means, and
the like, are not shown or discussed. The disposition and
use of such conventional elements will be apparent to
those skilled in the art.
DETAILED DESCRIPTION OF THE INVENTION
A wide variety of hydrocarbonaceous oils may be
upgraded by the process of this invention. In general,
any oil which contains an objectionable amount of oné or
more undesirable contaminants can be upgraded. For exam-
ple, an oil containing an undesirable concentration of one
:
1 1~9788
Ol _7_
or more metalliferous contaminants can be upgraded, i.e.
demetallized, by reduction of the metals concentration.
05 Oils containing an undesirably high concentration of one
or more sulfurous contaminants can be upgraded, i.e.,
desulfurized, by reduction of the sulfur concentration.
Oils containing an undesirably high concentration of one
or more nitrogenous contaminants can be upgraded, i.e.,
denitrified, by reduction of their nitrogen concentration.
Oils having an undesirably high concentration of asphal-
tenes can be upgraded, i.e. deasphalted by reduction of
their asphaltenes concentration. Oils having a viscosity
which is higher than desired can be upgraded to decrease
their viscosity by treatment according to the present
invention. Oils containing an undesirably high concentra-
tion of relatively higher molecular weight hydrocarbona-
ceous molecules can be upgraded according to the invention
to provide a product having a decreased concentration of
such higher molecular weight materials and an increased
concentration of lower molecular weight hydrocarbons, as
by cracking and decomposition of high mol~cular weight
heteronuclear compounds, polycyclic aromatics, etc.
For example, high molecular weight, nondistillable com-
pounds, such as asphaltenes, can be converted to distill-
able hydrocarbon compounds and lower molecular weight com-
pounds by upgrading according to the present invention.
In the coking embodiment, the oil is treated to
provide coke and a distillate of lower contaminant level,
lower molecular weight, and/or lower viscosity, etc,
Although any oil contaminated with one or more
of the contaminants discussed above or having an overly
;~ high boiling range or overly high viscosity, can be suita-
bly upgraded according to the present invention, the pre-
ferred feed oils are petroleum residuals, heavy petroleum
' crudes, shale oils, coal oils, tar sand oils (bitumens),
and analogous natural or synthetic oils and oil fractions.
For example, preferred feeds include such petroleum frac-
tions as atmospheric distillation bottoms streams, vacuum
distillation bottoms streams, catalytic cracking product
l 15978~ `
01 -8-
fractionator bottoms and slurry oils, and in general
petroleum, coal oil, tar sand oil, shale oil, or the like
or heavy fractions thereof, a substantial portion of which
has a normal boiling point above 565C. Preferred heavy
crude petroleum or tar sand oils for upgrading are those
with one or more of the following properties: an API
gravity of less than 20; a Ramsbottom carbon residue
factor of greater than 0.8; an asphaltenes (n-heptane
insoluble fraction) content of greater than 3 weight per-
cent; or a fraction of greater than l0 weight percent of
the oil boiling above 565C. Preferred feeds include
bitumen derived from tar sands, i.e., bituminous sands,
and heavy crudes and tars such as those found in the
Athabasca region of Canada and the Orinoco region of
Venezuela.
Preferred feed oils include oils having a sub-
stantial concentration of at least one metal selected from
nickel and vanadium. These metals are usually present in
crude oils and residual fractions in the form of organo-
metallic compounds, such as metalloporphyrins.
Preferred feed oils include oils having a sub-
stantial concentration of finely divided solid contami-
nants, which may be solid organic material, solid inor-
ganic material, or both. Examples of solids found in some
preferred feed oils are clay, sand, silt and such salts as
alkaline earth metal carbonates and silicates.
Preferred feed oils may be oils which are mixed
with small or large concentrations of aqueous liquids. In
fact, the present process provides a highly advantageous
way to dispose of waste slop oils, oil-water emulsions,
desalter separator cuff layers, contaminated oil bottoms
from storage tanks and the like.
The aqueous liquid used in the treatment of the
-~ present invention may simply be water or may be an aqueous
solution or suspension of one or more inorga~ic or organic
compounds or ions. In some cases, addition of solubie or
suspended materials can be beneficial to carrying out the
process in that the added material can catalyze reactions
1 159788
01 _9_
which take place in upgrading an oil. Preferred additive
materials include alkali metals, alkaline earth metals,
05 their ions and salts. Added extraneous materials, such as
alkali and alkaline earth metals, can be mixed with the
feed oil or with the oxygen-containing gas prior to con-
tacting the gas, water and oil at high temperatures, or
can preferably be premixed with the aqueous phase.
The temperature at which the present process is
carried out should usually be maintained above about
175C. For upgrading without substantial coking, the
reaction temperature is maintained between about 175C and
300C, particularly between about 195C and 260C. For
coking, the process is carried out at a temperature suffi-
cient to form coke from the feed oil. The temperatureshould usually be maintained above 300C, preferably
between about 315C and ~40C, particularly between about
325C and 425C. In either case, the elevated operating
temperature can be achieved solely by oxidation reactions
which occur after the oil, water and molecular oxygen are
contacted. One or more of the components can be preheated
prior to contact with the other components. The mixture
can also be heated by an external heat source after con-
tact. Often, heat exchange between the hot effluent from
the reaction zone and one or more of the aqueous feed, oilfeed or oxygen feed is advantageous in conserving heat
energy.
It will be apparent that the reaction tempera-
tures may not be uniform over the course of the reaction
time in carrying out many embodiments of the present pro-
cess, since oxidation reactions will tend to increase the
temperature of the reaction mixture over the extent of the
contact time, if free oxygen is not limited. Thus, in a
batch-type non-coking reaction, the reaction temperature
may start at a very low temperature, e.g. below 175C, and
rise to a high level, e.g. above 300C at the end of the
contact time. For coking, the temperature may start at a
very low temperature, e.g. below 300C, and rise to a high
level, which may even be above 540C by the end of the
l 159788
01
--10--
contact time. A similar temperature profile will often be
observed when a plug flow-type contacting scheme is
employed. In general, however, the reactants should be
maintained within the indicated temperature ranges for at
least a major portion of the total contact time. Prac-
tical contact times are usually those sufficient to allow
consumption of at least a major portion of the free oxygen
employed.
The pressure employed in the present process is
at least sufficient to maintain at least a portion of the
water, i.e., the aqueous phase, in the liquid state.
Preferably, a pressure is employed which is at least suf-
ficient to maintain the major portion of water present in
the reaction mi~ture as a liquid. Higher pressures have
the advantage of permitting relatively larger amounts of
free oxygen to be dissolved or diffused in the liquid
aqueous phase, but increased capital and operating costs
involved in the carrying out of higher pressure operations
usually set a practical upper limit on the pressure that
can economically be used.
According to the invention, free oxygen, i.e.,
molecular or atomic oxygen, or a precursor thereof, is
contacted with oil and an aqueous liquid. To supply the
free oxygen component for the process, pure molecular
oxygen gas (2 or O3) can be used. Gases, such as air,
which contain molecular oxygen mixed with one or more
diluent gases, such as nitrogen, steam, carbon dioxide,
etc., are also suitable for use. Solid, liquid or gaseous
compounds of combined oxygen, which decompose or react to
form atomic or molecular oxygen, such as hydrogen per-
~d ~ oxide, may be used to supply the free oxygen component.
. ~
The free oxygen component, or a precursor thereof, can be
mixed with the aqueous liquid prior to, simultaneously
with, or after contact is established between the aqueous
.,
liquid and the feed oil. The amount of free oxygen
~ employed relative to the amount of oil should be suffi-
! 40 cient to react with not more than a minor portion of the
~ `
1 159788
--11--
oil. Preferably, the free oxygen should not constitute
more than about 30 weight percent of the oil.
Contact of the feed oil with aqeuous liquid and
with free oxygen can be carried out in a suitable conven-
tional reactor or other suitable conventional vessel or
container means, which should be sufficiently resistant to
the temperatures, pressures, corrosive compounds and other
reaction conditions which are encountered in carrying out
the present invention. The oil, water and free oxygen
components can be contacted in a batch-type system or,
preferably, in a continuous type system. The oil, water
and oxygen components can be contacted in cocurrent flow,
in countercurren~ flow, in a stirred tank-type reaction
system, or in another analogous contact system. Prefer-
ably, contact is carried out in cocurrent flow through a
reaction zone, particularly preferably in upflow through a
vertically extending vessel. Preferably, at least a por-
tion of the free oxygen employed is dissolved in the
aqueous liquid prior to contacting the aqueous liquid with
the oil to be treated.
Preferably, oil and aqueous liquid are contacted
at an aqueous liquid-oil volume ratio in the range from
about 0.5:1 to about 10:1. Particularly preferably, an
aqueous liquid:oil volume ratio of about 1:1 to about 4:1
is used. Preferably, the feed oil i5 introduced into
contact with the aqueous liquid in finely divided form,
e.g. as droplets, as by using a mixer, diesel injector or
the like.
The product oil can be separated from the water
and gas by phase separation (settling, decantation, etc.)
or fractional ~istillation or the like conventional separ-
,
ation technique. The product oil can be used advanta-
geously in several ways. One advantageous use of the
product of a non-coking process is as a feed for a thermal
distillation or coking process. Suitable conventional
coking techniques include delayed coking and fluidized
coking. Another advantageous use for product oil is as a
feed for a catalyti~ cracking operation, especially for an
'
l 159788
01 -12-
FCC operation in which the oil is contacted with an
acidic, zeolite or non-7eolite catalyst in the absence of
05 added molecular hydrogen. A further advantageous use for
product oil is as a feed for a hydrogen treating process
such as hydrodemetalation, hydrodenitrification, hydrode-
sulfurization, hydrocracking or simple hydrogenation, in
which the oil is contacted with a Group VIB and/or Group
VIII metal on a porous carrier such as silica, alumina,
clays and the like. Suitable hydrogen treating catalysts
may include an acidic component such as silica-alumina, a
zeolite, etc. The product oil formed in the present pro-
cess can often be fractionated to provide high yields of
such products as diesel fractions, jet fuels, gasolines,
naphthas, etc.
As a byproduct of upgrading the feed oil, it may
be advantageous to generate steam from a portion of the
aqueous liquid, and the steam can be used to supply energy
for electrical or mechanical power generation. It should
be noted, however, that at least a portion of the aqueous
phase should remain as a liquid at the end of the contact-
ing period.
EXAMPLE 1
An atmospheric distillation residual oil frac-
tion from an Arabian Heavy crude was upgraded according to
the present invention in a series of bench scale tests
using an upflow, vertical reactor system. The properties
of the feed oil and product oils and the operating condi-
tions used in each test are shown in the Table. In
Test 2, 0.5 weight percent potassium hydroxide was dis-
solved in the water prior to the test. In Tests 4 and 5
hydrogen peroxide was &dded to the water to provide the
free oxygen component by decomposition. The API gravities
for the products as reported in Tests 1 and 2 in the table
were calculated from a TGA analysis. Distillation figures
were also calculated from TGA analyses. Feed oil was
mixed with water prior to introduction of the liquids into
; the upflow reactor in Tests 1 and 2. In Tests 3-6, oil was sprayed into the lower end of the reactor using a
:
l 159788
01 -13-
diesel injector, while water was introduced along with
hydrogen peroxide into the bottom of the reactor.
S Referring to the Table, it is apparent that upgrading an
atmospheric distillation bottoms feed according to the
present invention results in a substantially lighter prod-
uct (higher API gravity, lower boiling range), with fewer
heat-sensitive, nondistillable components such as asphal-
tenes (lower Ramsbottom carbon), with reduced concentra-
tion of metalliferous contaminants (Ni, V), a reduced
concentration of sulfurous contaminants (weight per-
cent S), a reduced concentration of nitrogenous contami-
nants (weight percent N), and a substantially decreased
Saybolt viscosity. The above-noted improvements were
advantageously obtained at an operating temperature much
lower than used in a conventional thermal cracking system.
EXAMPLE 2
An atmospheric distillation residual oil frac-
; tion was co~ed according to the present invention in abench scale test. The temperature employed was 371C.
The pressure employed was 67 atmospheres. Oil was fed at
a rate of 80 cc per hour. The feed was an Arabian Heavy
atmospheric residual fraction containing 3.4 weight per-
cent sulfur, 0.31 weight percent nitrogen, with a carbon
content of 84.5 weight percent and a hydrogen content of
11.0 weight percent. The test was performed in a cocur-
rent, upflow system in a simple reactor vessel. The coke
formed in the reactor was analyzed and found to contain
4.9 weight percent sulfur, 0.46 to 0.49 weight percent
nitrogen, 73.6 weight percent carbon and 4.~ weight per-
cent hydrogen. It had a heat of combustion of 12,613
BTU/pound (293,000 kJ/kg).
l 159788
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