Note: Descriptions are shown in the official language in which they were submitted.
CA 02549358 2006-05-30
HEAVY OIL UPGRADING PROCESS
BACKGROUND
[0001] Many fossil fuels such as hydrocarbons from oil sand deposits, tar
sands and bitumen,
herein referred to as heavy oil, contain polynuclear aromatics composed of
asphaltenes and
resins, heavy metals with nickel and vanadium being the predominant ones and
hetero-atoms
like oxygen, sulphur and nitrogen in their chemical composition. During
refinery operations,
the presence of asphaltenes results in the formation and/or separation of coke
- that plugs the
fixed bed of catalysts. The plugging of a catalyst bed by coke deleteriously
leads to the
formation of a layer of coke over the catalyst - a phenomenon that prevents
the catalyst from
functioning at its efficiency. The nitrogen, sulphur, nickel and vanadium in
heavy oils and
bitumen also have detrimental effect on refining operations in that they
constitute the
poisoning or de-activation agents of the catalyst. Thus the presence of
asphaltenes, heavy
metals and heteroatoms in heavy oil make the oil an undesirable feed for many
refinery
operations - specifically in fixed bed units or fluidized catalytic units and
ultimately has a
negative effect on the value or price of heavy oil.
SUMMARY
[0002] We disclose here a process for the upgrading of heavy oil that provides
a solution to
catalytic poisoning by substantially reducing the concentrations of
contaminants to levels that
enable the residual product to be used as a desirable feedstock for
refineries.
[0003] In one embodiment of a heavy oil upgrading process, the concentrations
of
contaminants of heavy oils can be reduced substantially by dissolving the
heavy oil in a de-
asphalting hydrocarbon solvent to separate the insoluble asphaltenes from the
soluble oil
fraction, and thereafter subjecting the oil fraction to oxidization, including
biological and
chemical treatrnents.
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[0004] In one embodiment, a heavy oil upgrading process uses a hydrocarbon
solvent
composed of a mixture of paraffinic, iso-paraffininc and aromatic solvents
ranging from C4 to
C 10 hydrocarbons in the de-asphalting of heavy oils to produce asphaltenes
that are black
shiny crystalline solids that are easily separated from the heavy oil.
Examples of the
constituents of the solvent include butane, iso-butane, n-pentane, iso-
pentane, n-heptanes, iso-
octane and metaxylene with iso-octane being the preferred solvent.
[0005] For example, in the de-asphalting step the heavy oil may be initially
contacted with the
solvent and heated to a moderate temperature. The mixture is maintained at
temperatures in
the range of 75 C-110 C for a period of 2 to 3 hours. Following the
dissolution of the oil
over a pre-determined time, the asphaltenes are separated from the oil through
gravity or
vacuum filtration. Due to the nature of the solvent used in the de-asphalting
phase, the
asphaltenes recovered are black, shiny and crystalline solids that are easily
separated from the
oil fraction.
[0006] In one embodiment of a heavy oil upgrading process, bio-chemical
catalytic oxidation
of nickel, vanadium, sulphur, nitrogen and unsaturated compounds present in
high
concentrations in heavy oil is conducted in the presence of biological and/or
chemical
reagents at moderate temperatures and pressures.
[0007] In another embodiment of a heavy oil upgrading process, pressures in
the range of 1
atm to 14 atm are applied along with oxidizing reagents and catalysts to
reduce the
concentrations of metallic contaminants, unsaturated compounds, and hetero-
atoms such as
sulphur and nitrogen contained in heavy oil.
[0008] In another embodiment of a heavy oil upgrading process, an adsorbent
material is used
along with the biological and chemical reagents to absorb the oxidized
products from the
heavy oil. In one embodiment, a heavy oil upgrading process enhances the API
gravity of the
heavy oil from less than 10 to 30 and above by reducing the concentrations of
contaminants
contained in the oil by a minimum of 50% by weight.
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[0009] In one embodiment of a heavy oil upgrading process, the de-asphalted
oil is contacted
with biological reagents that contain enzymes that catalyze the oxidation of
the contaminants
in the oil. In one embodiment of a heavy oil upgrading process, biological
materials or
agricultural wastes are used as reagents to upgrade heavy oil into products
that are acceptable
as refinery feedstock. The biological oxidation in one embodiment is
accomplished by the
introduction of an oxidant and an adsorbent along with the biological reagents
into the de-
asphalted oil and then subjecting the mixture to temperatures of between 85 C
and 150 C
and at pressures ranging from I atm to 14 atm for a period of time, preferably
between 2 to 3
hours, and thereafter separating the oil from the oxidized contaminants. The
oil from this
stage is then subjected to chemical oxidation by the introduction of chemical
reagents
including adsorbents into the oil and heating the mixture to between 105 C
and 180 C for 1
hour to 3 hours at between 1 atm and 14 atm. Upon completion of the chemical
treatment, the
oil is separated from the oxidized contaminants through filtration.
[0010] In one embodiment of a heavy oil upgrading process, adsorbents are
added to the oil to
extract from the bio-chemically treated oil the polar or oxidized compounds.
The separation
of the adsorbent and any or all accompanying oxidized compounds from the
oxidized oil may
be, for example, accomplished through gravity or vacuum filtration, or
preferably through a
centrifuge or pressure leaf filter. The oil recovered from the oxidized
contaminants is
composed of the upgraded oil and the de-asphalting solvent which is ultimately
separated
from the upgraded oil. The separation of solvent from the upgraded oil may be
achieved by
various processes such as distillation. The residual oil, following the
separation of the
solvent, is an upgraded oil which is substantially reduced in contaminants'
concentration and
possesses characteristics that make it acceptable as a refinery feed stock.
[0011] In one embodiment, a heavy oil upgrading process provides a bio-
chemical catalytic
process for the oxidation of nickel, vanadium, sulphur, nitrogen and
unsaturated compounds
by the application of waste biological reagents in the oxidation of the
contaminants and also
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the application of waste iron oxide along with other chemical reagents
including a hydrogen
donor solvent such as acetic acid.
[0012] In one embodiment, a heavy oil upgrading process provides still a bio-
chemical
catalytic oxidation of nickel, vanadium, sulphur, nitrogen and unsaturated
compounds
contained in heavy oils and bitumen at pressures ranging from 1 atm to 14 atm
and at
temperatures between 85 C and 180 C for 1 hour to 3 hours.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Embodiments of a heavy oil upgrading process will now be described by
way of
example with reference to Fig. 1, which is a flow diagram of a heavy oil
upgrading process.
DETAILED DESCRIPTION
[0014] This detailed description of a heavy oil upgrading process is exemplary
and not
intended to limit the scope of the claimed heavy oil upgrading process.
Immaterial variations
from the precise examples set forth here are intended to be included within
the scope of the
claims. In the claims, the word "comprising" is used in its inclusive sense
and does not
exclude other elements being present. The indefinite article "a" before a
claim feature does
not exclude more than one of the feature being present.
[0015] Heavy oil from source 10 is transferred to tank 14 where it is mixed
with solvent from
tank 12. The mixture is heated (source of heat not shown) for a desired period
of time; and
upon completion of the reaction between the solvent and the heavy oil, the
insoluble
asphaltenes are separated through the separation device 16. The asphaltenes
are collected and
stored in tank 36 while the de-asphalted oil is transferred to Tank 24. Tank
18 contains
biological reagents that are added to the contents of tank 24 where biological
oxidation takes
place. The biologically oxidized oil is separated from the oxidized
contaminants through
separator 30 and transferred to reactor 28 leaving the residue which is stored
in tank 38.
Cheniical reagents from Tank 22 are added to the contents of reactor 28 for a
chemical
oxidation phase. Following the chemical oxidation, the oxidized oil is
separated from the
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oxidation residue through separator 34. The chemical oxidation residue is
transferred to
storage tank 42 while the oxidized oil is transferred to distillation unit 44
where the initial de-
asphalting solvent is separated from the upgraded oil through atmospheric or
vacuum
distillation. The solvent recovered is transferred back into Tank 12 while the
upgraded oil
from unit 44 is collected and stored in Tank 48.
[0016] The heavy oil upgrading process described here reduces problems
associated with high
asphaltenes content and high contaminants' concentrations of heavy oil. The
heavy oil
upgrading process provides a process for upgrading heavy oil to crude oils
with characteristics
that enable them to be used as refinery feedstock. The heavy oil upgrading
process provides
the dissolution of the heavy oil in a hydrocarbon solvent comprising of
paraffinic, iso-
paraffinic and/or aromatic solvents. This solvent, by virtue of its
composition rejects the
asphaltenes which separate from the oil as black, shiny, hard and crystalline
solids. Following
the separation of asphaltenes from the oil, the heavy oil upgrading process
provides the
application of biological and chemical reagents for the reduction of
contaminants'
concentration from the de-asphalted oil. An embodiment of the heavy oil
upgrading process
comprises the steps of solvent de-asphalting followed by bio-chemical
treatments as
illustrated in FIG 1. Initially, an amount of the hydrocarbon solvent is added
to a specified
mass of heavy oil or bitumen to give a solvent to oil ratio where the minimum
solvent to oil
volume ratio is 4:1 and a maximum solvent to oil volume ratio is 40:1 with
10:1 being the
preferred solvent to oil volume ratio.
[0017] The exemplary hydrocarbon solvent herein described is a mixture of
straight and
branch chained paraffinic and aromatic solvents ranging from C4 to C I O
examples of which
include butane, iso-butane, n-pentane, iso-pentane, n-heptanes iso-octane and
metaxylene
with iso-octane being the preferred solvent. The mixture is heated at
atmospheric pressure to a
desired temperature and for a time sufficient to cause dissolution of the
heavy oil in the
solvent. The mixture may be heated to a minimum temperature of 60 C and a
maximum
temperature of 120 C, the preferred temperature being in the range of 105 C-
115 C under
reflux. The residence time may range from one hour to four hours and most
preferably from
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two to three hours. Under these conditions, the asphaltenes are separated from
the oil as
insoluble crystalline black shiny solids and recovered through a proper
separation device. A
suitable separation device comprises gravity or vacuum filtration. The amount
of asphaltenes
that are typically recovered through this heavy oil upgrading process is
approximately 16-20
% weight of the heavy oil, although this can vary depending on the source of
the heavy oil
and also on the operating parameters of the de-asphalting process.
[0018] Following the de-asphalting phase of the heavy oil upgrading process,
biological
reagents are introduced to a reactor containing a mass of the de-asphalted
oil, the minimum
mass of the said de-asphalted oil being 50 g and a maximum mass being 2 kg
with 750 g as
the preferred mass in this example. The biological reagents are selected from
agricultural
wastes, examples of which comprise peat moss, canola hulls, peanut shells,
soybean hulls, and
cellulose. The biological reagents contain enzymes that are capable of
operating at high
temperatures and low pH conditions and also catalyze the oxidation of the
contaminants,
particularly nickel and vanadium to their respective oxides at the expense of
an oxidizing
agent. The addition of the oxidizing agent follows the biological reagents.
The oxidizing agent
may comprise oxides of metals of Group IIA such as calcium and magnesium, or
oxides of
metals of Group VIII such as cobalt, nickel, copper or iron as well as their
combinations.
Other oxidizing agents which may be used comprise oxygen, air, ozone, hydrogen
peroxide,
chlorine, per-acetic acid, formic acid, per-benzoic acid, benzoic acid, and
acetic acid. The
oxidant, when applied in a liquid form is preferentially added in a range of
0.5 % volume to
5.5 % volume of the heavy oil/bitumen feed, although volume percentages of
between 0.1 %
and 7.2 % are also suitable for the process.
[0019] A further embodiment of the heavy oil upgrading process is the
introduction of an
adsorbent selected from among materials such as: fullers' earth, alumina,
zeolite, clay, silica
gel, peat moss or a combination of two or more of them into the reaction
chamber. Preferred
adsorbents are alumina, peat moss, clay or their combinations. In one
embodiment, the
adsorbent is applied as a weight percentage of the heavy oil or bitumen from
between 0.055%
weight and 6.5% weight with the preferred range being 2.5% weight to 5.5%
weight.
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[0020] The biological oxidation, according to one embodiment of the heavy oil
upgrading
process, is carried out at pressures ranging from 1 atm to 14 atm and at
temperatures ranging
from 85 C to 150 C, and over a period of time ranging between 2 and 3 hours.
Following
the biological oxidation of the de-asphalted oil, the oxidized oil is
separated from the
contaminants by means of a suitable separation device. Such a device may
comprise gravity
filtration, vacuum filtration, centrifugation, or pressure-leaf filtration.
[0021] A further embodiment of the heavy oil upgrading process comprises the
introduction
of chemical reagents to the biologically oxidized oil in a second reactor. The
preferred
chemical reagents comprise catalysts, examples of which comprise alumina,
activated carbon,
bituminous coal, lignite char or coconut char. Oxides of Group VIII metals
have also been
found to be useful as oxidation catalysts with the preferred such catalyst
being iron oxide. As
an embodiment of this heavy oil upgrading process, iron oxide is derived
exclusively from a
waste hydrometallurgical metal processing plant. A hydrogen donor solvent,
preferably a
carboxylic acid solvent may also be employed. Preferred carboxylic acids may
comprise
formic or acetic acid. As a further embodiment of the heavy oil upgrading
process, any one of
the oxidants used in the biological oxidation phase can be used in the
chemical oxidation. As
well, the most preferred oxidants comprise iron oxide, water, and hydrogen
peroxide or a
mixture of aqueous hydrogen peroxide and an acid. As another embodiment of the
heavy oil
upgrading process, any one of the adsorbents used in the biological oxidation
phase can be
used in the chemical oxidation.
[0022] The mixture of oil, chemical reagents and adsorbent may be heated to a
sufficient
temperature and sufficient pressure over a sufficient amount of time. These
parameters
comprise a temperature range of 105 C to 180 C, pressures ranging between 1
atm and 14
atm, and times ranging from 1 hour to 3 hours. Thereafter, the chemically
oxidized oil is
separated from the contaminants via a separation device. Examples of such
separation devices
comprise gravity filtration, vacuum filtration, centrifugation and pressure
filtration.
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[0023] The oil recovered from the separation unit is further subjected to yet
another
separation system to recover the upgraded oil from the de-asphalting solvent.
As an
embodiment of the heavy oil upgrading process, the preferred method of
separating the
solvent from the upgraded oil is by either atmospheric or vacuum distillation.
The solvent
recovered from the distillation unit is re-used in subsequent de-asphalting
phases of the
upgrading process. The residual product, following the separation of the
solvent is the
upgraded oil which is substantially reduced in contaminants' concentration as
disclosed by the
results of the chemical and physical analyses of the product. As an embodiment
of the heavy
oil upgrading process, the chemical oxidation process can precede the
biological oxidation.
EXAMPLES OF EXPERIMENTAL WORK
Example 1
[0024] This example illustrates the effect of using virgin and recycled
solvent in the de-
asphalting phase of the upgrading process.
[0025] In a 1L beaker was accurately weighed 5g of Alberta heavy oil. IOOmL of
virgin
solvent was added to the heavy oil to give a 20:1 solvent to oil ratio and the
mixture was
stirred with heat from a hot plate until the formation of an emulsion was
observed. With
continuous stirring, the mixture was heated to a moderate temperature and
thereafter,
transferred to a 3-neck round bottom 1L flask provided with a reflux condenser
and a
thermometer, where the mixture was heated with further stirring for 3 hours at
a temperatures
ranging from 60 C to 100 C. The mixture was allowed to cool to ambient
temperature and
thereafter, the asphaltenes were separated from the de-asphalted oil through
filtration, and the
weight of dry asphaltenes was recorded. This experiment was repeated five
times and the
average weight of asphaltenes determined. From the average weight of
asphaltenes, the
weight percent of the asphaltenes, based on the initial weight of 5g of the
heavy oil, was
calculated. In similar experiments, previously used solvent was used in de-
asphalting
experiments as described above. The average weight of asphaltenes recovered
from the five
experiments with the recycled solvents was determined and the weight percent
of the
asphaltenes calculated. The weight percent of the asphaltenes recovered from
the experiments
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with the virgin solvent was approximately 18% while the weight percent of the
asphaltenes
recovered from the experiments with the previously used solvent was
approximately 13%.
[0026] The following examples are based on investigations conducted with
samples of de-
asphalted oil derived from composite de-asphalted oil prepared from the
reaction between
Alberta heavy oil and the solvent.
Example 2
[0027] This example illustrates the application of a heavy oil upgrading
process. Into a 3-neck
1L round bottom flask was measured 350mL sample of de-asphalted oil. 3g of
biological
reagent A (soybean hulls) and 2g of biological reagent B (peanut shells) were
added to the de-
asphalted oil followed by the addition of 1mL of oxidant. Using a magnetic
stirrer, the
mixture was subjected to stirring while being heated to 175 C for 3 hours.
During the reaction
between the oil, the biological reagents, and the oxidant, the enzymes in the
agricultural waste
or the biological reagents catalytically oxidized the contaminants in the oil.
This resulted in
the formation of the oxides of nickel and vanadium. Following the biological
oxidation, the
oil was separated from the oxidized by-products through filtration. The
filtrate was transferred
to another 3-neck 1L round bottom flask to which the chemical reagents were
added. The
chemical reagents included activated carbon, iron oxide oxidant, a hydrogen
donor solvent,
water, and the adsorbent. The mixture was subjected to chemical oxidation by
heating it to a
temperature range of 120 C - 140 C for 3 hours and at pressures ranging
between latm and
14atm. Following the chemical oxidation, the mixture was cooled and filtered.
The oxidized
contaminants from the oil, which included the oxides of the metals nickel and
vanadium, were
thus separated from the oil. The post-treated oil was analyzed for its
contaminants
concentrations. Table 1 contains the results of the analyses of the upgraded
oil.
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[0028] Table 1
Properties of Concentration of Concentration of Concentration of
oil contaminants in contaminants in oil contaminants in oil treated
the heavy oil as is treated with Biological with oxidant only and NO
Reagents Biological Reagents
SG @ 60/60oF 1.000 0.8415 0.9088
API Gravity 11 37 24
Ni (ppm) 45 14 21
V (ppm) 128 30 58
S (wt %) 6.20 2.62 4.47
Example 3
[0029] This example illustrates the effect of using biological reagents as
catalysts in the
upgrading process. Into a 3-neck 1L round bottom flask was measured 500mL of
de-asphalted
oil. Specified amounts of the two biological reagents, A (soybean hulls) and B
(peanut shells)
were added followed by the addition of an oxidant. Upon heating the mixture
for 2 hours at a
temperature of 1500C, the mixture was cooled and filtered. The filtrate, which
was a mixture
of the de-asphalting solvent and the biologically upgraded oil, was subjected
to a separation
process from which the solvent was recovered from the upgraded oil. In a
comparable
experiment, 500mL of de-asphalted oil was oxidized under the same experimental
conditions
as before, including the same amount of oxidant, but without any biological
reagents.
Following the separation of the solvent from the upgraded oil, contaminants
concentrations of
the two upgraded oils were determined. The results are contained in Table 2.
CA 02549358 2006-05-30
[0030] Table 2
Properties of Oil Un-treated Heavy Oil Upgraded oil by the Process %
Contaminant Removed
SG @60/60oF 1.007 0.8475 N/A
API Gravity 11 35 N/A
Ni (ppm) 42 14 69
V (ppm) 128 39 70
S (wt %) 6.20 3.01 52
N (wt %) 0.30 0.11 63
[0031 ] Tables 3 and 4 contain some physical and chemical data of upgraded
crude oils with
characteristics of a refinery feedstock produced from the bio-chemical
catalytic oxidation
process of the present heavy oil upgrading process.
[0032] Table 3
Parameter Method Alberta Heavy 45/55 59/60
Oil Upgraded Upgraded
Crude Oil Crude Oil
Abs Density @ 150C ASTM D5002 998 g/M3 811.5 kg/m 828.8 kg/m
API Gravity @ 150C N/A 10 43 39
Relative. Density @ 15oC ASTM D5002 1.007 0.8122 0.8295
Total Sulphur ASTM D5453 6.20 Mass % 1.8 Mass % 2.67 Mass %
Total Nitrogen ASTM D5291 0.30 Mass % 0.11 Mass % 0.10 Mass %
Nickel ASTM D5708A 45 mg/kg 8.5 mg/kg 11 mg/kg
Vanadium ASTM D5708A 128 mg/kg 27 mg/kg 33 mg/kg
MCR ASTM D4530 N/A 2.68 2.72
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[0033] Table 4 contains a summary by carbon of the fractional composition of a
crude oil
produced by the bio-chemical catalytic oxidation of Alberta heavy oil.
[0034] Table 4
C# %Wt % Vol. %Mol
C5 0.007 0.008 0.011
C7 4.119 3.518 5.466
C8 59.225 61.474 63.902
C9 2.322 2.195 2.274
C 10 20.461 19.940 17.740
C 11 6.827 6.545 5..413
C12 0.588 0.519 0.437
[0035] In one embodiment, a heavy oil upgrading process provides further a bio-
chemical
catalytic oxidation process for obtaining, from heavy oils and bitumen
containing 6.20 %
weight of sulphur and 0.30 % weight of nitrogen as well as 45 ppm of nickel
and 128 ppm of
vanadium, an upgraded oil containing a minimum of 50% of the original
contaminants.
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