BITUMEN MODIFICATION USING FLY ASH DERIVED FROM BITUMEN COKE

MODIFICATION DE BITUME A L'AIDE DE CENDRES VOLANTES PROVENANT DE COKE DE BITUME

English Abstract

A method for lowering the viscosity and specific gravity of a heavy hydrocarbon to render it pipelineable is disclosed. The method comprises adding a vanadium and nickel containing coke fly ash to the heavy hydrocarbon; reacting the heavy hydrocarbon in the presence of the fly ash with a molecular hydrogen containing gas under hydroconversion conditions for a time sufficient to lower the viscosity of the hydrocarbon in the range of about 20 to 60 centipoise at 40°C and to lower the specific gravity in the range of from about 0.925 to about 0.940 at 15°C, whereby the heavy hydrocarbon is rendered pipelineable.

French Abstract

Procédé permettant d'abaisser la viscosité et la densité d'un hydrocarbure lourd pour le rendre transportable par pipeline. Le procédé comprend l'addition de cendre volante de coke contenant du vanadium et du nickel à l'hydrocarbure lourd ; la réaction de l'hydrocarbure lourd en présence de la cendre volante avec un gaz contenant de l'hydrogène moléculaire dans des conditions d'hydroconversion pendant une durée suffisante pour abaisser la viscosité de l'hydrocarbure dans la plage d'environ 20 à 60 centipoises à 40.degrés.C et pour abaisser la densité dans la plage d'environ 0,925 à environ 0,940 à 15.degrés.C, moyennant quoi l'hydrocarbure lourd est rendu transportable par pipeline.

Claims

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THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for lowering the viscosity and specific gravity of a heavy
hydrocarbon to render it pipelineable which comprises:
adding to the hydrocarbon a coke fly ash containing greater than
about 5000 ppm vanadium and 2000 ppm nickel;
reacting the hydrocarbon in the presence of the coke fly ash with a
molecular hydrogen containing gas under hydroconversion conditions for a time
succient to lower the viscosity of the hydrocarbon in the range of about 20 to
about 60
centipoise at 40°C and to lower the specific gravity in the range of
about 0.925 to about
0.940 at 15°C whereby the hydrocarbon is rendered pipelineble.
2. The method of claim 1 wherein the fly ash is added in an amount
of about 5 to about 25 wt.% based on the weight of hydrocarbon.
3. The method of claim 2 the hydrocarbon is reacted at a temperature
between about 400°C to about 450°C and hydrogen partial pressure
of about 800 to
1500 psig..
4. The method of claim 3 including first roasting the coke fly ash at
an elevated temperature to a constant weight.
5. The method of claim 3 or 4 wherein the fly ash is sulfided.
6. The method of claim 5 including separating the fly ash after the
reacting step.
7. The method of claim 6 including recycling the separated fly ash.
8. A method for lowering the viscosity and specific gravity of a heavy
hydrocarbon containing a substantial portion of material boiling above
525°C to render
it pipelineable which comprises:

obtaining a fly ash containing greater than about 5000 ppm
vanadium and 2000 ppm nickel;
contacting the fly ash with elemental sulfur or a sulfur containing
gas at a temperature and for a time sufficient to sulfide the fly ash;
adding from about 5 to about 25 wt.% of the fly ash to the
hydrocarbon, based on the weight of hydrocarbon;
reacting the hydrocarbon in the presence of the fly ash under
hydroconversion conditions for a time sufficient to lower the hydrocarbon
viscosity to a
range of about 20 to about 60 centipore at 40°C and the specific
gravity to a range of
about 0.925 to about 0.940 at 15°C whereby the hydrocarbon is rendered
pipelineable.
9. The method of claim 8 wherein the fly ash is derived from a
bitumen coke.
10. The method of claim 9 wherein the fly ash is roasted at an elevated
temperature to a constant weight.
11. The method of claim 10 wherein the fly ash is separated after
reacting the hydrocarbon and is recycled.

Description

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FIELD OF THE INVENTION
This invention relates to the modification of heavy hydrocarbons such as
bitumen from oil sands to render them pipelineable.
BACKGROUND OF THE INVENTION
With the decrease in the reserves of conventional crude oils, there is
increasing use of heavy hydrocarbons such as those extracted from oil sands.
These
heavy hydrocarbons contain a wide range of materials including usually more
than 50
wt.% of material boiling above 525°C, equivalent atmospheric boiling
point.
In order to transport these heavy hydrocarbons to a point of use, the
bitumen typically is mixed with a diluent such as natural gas condensate to
reduce the
viscosity of the bitumen for pipelining.
Unfortunately, the supply of natural gas condensate may not keep pace
with the continuing growth in use of such heavy hydrocarbons. Therefore, there
is a
need for a method to reduce the viscosity of bitumen to render it pipelineable
without
adding diluent.
SUMMARY OF THE INVENTION
Accordingly, there is provided a method for lowering the viscosity and
specific gravity of a heavy hydrocarbon to render it pipelineable which
comprises adding
a vanadium and nickel containing coke fly ash to the heavy hydrocarbon;
reacting the
heavy hydrocarbon in the presence of the fly ash with a molecular hydrogen
containing
gas under hydroconversion conditions for a time sufficient to lower the
viscosity of the
hydrocarbon in the range of about 20 to 60 centipoise at 40°C and to
lower the specific
gravity in the range of from about 0.925 to about 0.940 at 15°C,
whereby the heavy
hydrocarbon is rendered pipelineable.
DETAILED DESCRIPTION OF THE INVENTION
The heavy hydrocarbon materials suitable for the use in the practice of
the present invention are those which contain a substantial portion, i.e.,
greater than 50

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vol.% of material boiling above 525°C, equivalent atmospheric boiling
point. Indeed, of
particular interest are the heavy hydrocarbon oils extracted from oil sands
most
particularly Athabasca and Cold Lake oil sands. Typically, such heavy
hydrocarbons at
40°C have a viscosity exceeding 5,000 centipoise and a specific gravity
greater than 1.
The fly ash utilized in the practice of the present invention typically is
material that contains greater than about 5,000 ppm vanadium and greater than
about
2,000 ppm nickel as well as other metals, silica and clay. It is especially
preferred that
the fly ash be derived from burning Cold Lake or Athabasca bitumen derived
coke.
Such fly ash may contain as much as 50 wt.% carbon a majority of which may be
organic carbon. Thus in one embodiment of the invention, the carbon containing
fly ash
is roasted in a furnace at elevated temperatures, e.g., at about 700°C
preferably to a
constant weight, to lower the carbon content. This has the advantage that the
mass of
fly ash required is less than if not roasted. A typical elemental analysis of
a suitable fly
ash and roasted fly ash are given in Table 1 below.
TABLE 1
Element Flv Ash (,~pm~ Roasted Fly Ash (ppm)
Ca 8,790 22,000
Si 78,000 183,000
S 33,000 7,000
Fe 27,000 . 63,000
Mn 750 1,800
Mo 850 5090
Ni 6,400 21,000
Ti 10,500 23,500
V 14,250 33,800
C 48.8 0
In the practice of the present invention, the fly ash is added to the heavy
hydrocarbon in the range of about 5 wt.% to about 25 wt.% based on the weight
of
heavy hydrocarbons. Thereafter, the resulting mixture is reacted with a
molecular
hydrogen containing gas preferably as a slurry under hydroconversion
conditions. The
term hydroconversion is used herein to designate a process conducted in the
presence of

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hydrogen in which a portion of the heavy constituents of the hydrocarbon feed
is
converted to lower boiling hydrocarbon products. Typical hydroconversion
conditions
include maintaining the reactants at a temperature ranging from about
400°C to about
450°C preferably from about 400°C to about 435°C at a
hydrogen partial pressure
ranging from about 800 to about 1500 psig and preferably from about 1,000 to
about
1,200 psig.
The slurry of heavy hydrocarbon and coke fly ash is reacted for a time
suffcient to lower the viscosity of the heavy hydrocarbon at 40°C
within the range of
about 20 to 60 centipoise, and preferably within 40 to 50 centipoise and the
specific
gravity at 15°C within the range of about 0.940 to 0.925. Thereafter,
it is preferred to
separate the so treated hydrocarbon from the fly ash. Optionally, the
recovered fly ash
can be recycled for use in the process of the invention with or without
roasting.
In the practice of the present invention, it is particularly preferred to
convert only about 60 to 70 wt.% of the heavy hydrocarbon as measured by ASTM
test
method D 1160 or ASTM test method D2887. Under these conditions, there is
substantially no coke formation or asphaltene precipitation and the production
of
gaseous materials is on the order of 3 to 4 wt.%.
As will be readily appreciated, the vanadium, nickel and other metals in
coke fly ash used in the process of the present invention are present largely
as metal
oxides. Therefore, in one embodiment before adding the fly ash to the heavy
hydrocarbon the fly ash is first sulfided. Optionally, the fly ash may be
sulfided in the
presence of the hydrocarbon. In either case, sulfiding is readily achieved by
reacting the
fly ash or mixture of fly ash and hydrocarbon as the case may be, with
elemental sulfur
or a sulfur containing gas, such as hydrogen sulfide in an amount and at a
temperature
sufficient to convert at least a portion of the metal oxide to the
corresponding sulfides.
Typical temperatures are above room temperature up to about 385°C.
Generally at least
a stoichiometric amount of sulfur will be employed.
The following examples will illustrate the invention.

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EXAMPLES 1 AND 2
Two batch tests were conducted each using a bitumen having the
properties shown in Table II below, one test using fly ash (Example 1) and the
other
using roasted fly ash (Example 2). In Example 1 a 1 liter stirred autoclave
reactor was
charged with 275g of Cold Lake bitumen and 20g of coke fly ash. H2S gas was
added
to about 200 psig. Then hydrogen was added to increase the pressure to about
600
psig. Heating was initiated while stirnng the autoclave (2000 rpm) and the
autoclave
was heated to about 380°C for 30 minutes to allow catalyst sulfiding to
occur. The
reactor pressure was then increased to about 1300 psig with hydrogen and
continuous
hydrogen flow was initiated. At the same time, heating was resumed until the
target
temperature of 420°C was reached. The reactor was held at 422°C
for about 90
minutes. The heater was then removed, the autoclave was cooled and hydrogen
flow
was stopped. When the temperature of the fluids was less than 300°C,
the pressure was
then vented through a cooled knock-out vessel. When the reactor was at ambient
pressure a small hydrogen purge was initiated to remove any remaining acid
gas. The
reactor was then opened at a temperature of 150 to 175°C and the
contents were rapidly
vacuum filtered while hot. After cooling this filtered fraction (217g) was
recombined
with the light fraction collected in the knock-out vessel (38g). The
properties of the
product oil were then measured and are given in Table 2.
In Example 2, coke fly ash was replaced with coke fly ash which had
been roasted at 700°C to constant weight prior to use. The composition
of this roasted
fly ash is found in Table 1. This autoclave run was conducted exactly as per
Example 1
except in this case, the autoclave was charged with 251 g of bitumen and 1
O.Og of
roasted coke fly ash. In this example, the reactor was heated to 418°C
for about 2
hours. The properties of the product oil are found in Table 2.

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Table 2
Bitumen Example 1 Example 2 Example
3
Cold Lake Product Product Product
Specific 0.9972 0.9397 0.9327 0.9267
Gravity
Viscostiy, 7050 32 18 17
cP
@40C
Sulfur, Wt.%4.62 3.1 2.9 2.3
Ni (ppm) 72 54 60 20
V (ppm) 172 93 95 28
525C+Resid 51 29 25 17
(%)
EXAMPLE 3
In a fizrther example, the beneficial properties of fly ash were
demonstrated in a continuous lab pilot unit consisting of a tubular reactor. A
feed batch
was prepared by blending 6.8 wt.% Athabasca bitumen coke fly ash with Cold
Lake
bitumen. The feed and catalyst mixture was then mixed with hydrogen in-line,
pumped
through a pre-heater coil to a heated tubular reactor 2.54 cm in diameter and
22.1 cm in
length. The reactor was maintained at 445°C and 1000 psig with a liquid
residence time
of about 1 hour. The reactor products were separated in 2 stages to recover
the liquid
product and separate the reaction gases. The reactor had no internals and no
mixing
was provided. The final liquid product was pressure filtered with nitrogen
gas. The
filtered liquid product had a viscosity of 17 cP at 40°C and a specific
gravity of 0.9267
at 15°C per Table 2.