Note: Descriptions are shown in the official language in which they were submitted.
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LOW COMPLEXITY, HIGH YIELD CONVERSION OF HEAVY
HYDROCARBONS
FIELD OF THE INVENTION
The present invention relates to an optimized method of improving
a heavy high asphaltene hydrocarbon, such as bitumen, to a lighter more fluid
product and, more specifically, to a final hydrocarbon product that is
refinery-
ready and meets pipeline transport criteria without the addition of diluent. A
solid
asphaltene by-product is created for easy handling and further processing. The
invention is targeted to enhance Canadian bitumen, but has general application
in improving any heavy high asphaltene hydrocarbon.
BACKGROUND OF THE INVENTION
A low complexity, high yield integrated process has been
developed, tested and enhanced to improve the viability and economics of
converting heavy viscous hydrocarbons into desired refinery feedstock. The
concept for this integrated process has been previously described in US PAT
APP# 13/037185 and US PAT APP# 13/250935, and has been validated through
pilot plant (5 BPD) and demonstration scale (1500 BPD) facilities.
Improvements
to the integrated process through shear mixing have been disclosed in US PAT
APP# 61/548915.
This invention describes the optimal operating conditions to achieve
the lowest complexity and highest yield for the described integrated process.
=
The integrated process operates at temperatures, pressures, heat fluxes,
residence times, sweep gas rates and solvent to oil ratios outside any open
art
processes. The reduced capital and operating costs with the high liquid
product
yield for this novel integrated process, from the novel combination of all
these
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conditions, and choices of solvent, make it a high return opportunity for any
heavy oil producers.
DESCRIPTION OF PRIOR ART
Processes have been disclosed to convert and/or condition Oil
Sands bitumen into pipeline transportable and refinery acceptable crude. Of
note, thermal cracking, catalytic cracking, solvent deasphalting and
combinations
of all three (for example, visbreaking and solvent deasphalting) have been
proposed to convert bitumen to improve its characteristics for transport and
use
as a refinery feedstock.
Thermal Cracking
Visbreaking or viscosity breaking, a form of thermal cracking, is a
well known petroleum refining process in which heavy and/or reduced crudes are
pyrolyzed, or cracked, under comparatively mild conditions to provide products
that have lower viscosities and pour points, thus reducing required amounts of
less-viscous and increasingly costly to obtain blending hydrocarbons known as
diluent to improve fluidity of the crude, and make the crude meet minimum
transport pipeline specifications (minimum API gravity of 19).
There are two basic visbreaking configurations, the coil-only
visbreaker and the coil-and-soak visbreaker. Both require heaters to heat the
crude, with the coil-only style employing cracking only in the heater tubes.
Coil-
only visbreakers operate at about 900 F at the heater outlet with a residence
time
of about 1 minute. Gas oil is recycled to quench the reaction. In the coil-and-
soak visbreaker, a vessel is used at the outlet of a furnace to provide
additional
residence time for cracking of the crude. The crude sits and continues to
crack/react as the temperature slowly reduces. The coil-and-soak visbreaker
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runs at heater outlet temperatures of 800 F. The soaker drum temperature
reduces down to 700 F at the outlet with aggregate residence times of over 1
hour.
Examples of such visbreaking methods are described in Beuther et
al., "Thermal Visbreaking of Heavy Residues", The Oil and Gas Journal. 57:46,
Nov 9, 1959, pp. 151-157; Rhoe et al., " Visbreaking: A Flexible Process",
Hydrocarbon Processing, January 1979, pp. 131-136; and US Pat. No.
4,233,138. The yield structure is approximately same for either configuration:
1-
3% light ends, 5%(wt) naphtha and 15%(vt) gas oil. The remainder remains as
heavy oil or bitumen. The products are separated in a distillation column for
further processing or blending.
A concern with standard visbreaking schemes is that for Canadian
Bitumen, the operating temperatures are above the limit (around 700 F-720 F)
where significant coking impacts operability (Golden and Bartletta, Designing
Vacuum Units (for Canadian heavy crudes), Petroleum Technology Quarterly,
Q2, 2006, pp. 105). In addition, heat is added over a short period of time in
the
heater, so local heat fluxes are not uniform and can peak well above coking
initiation limits; and the heat is not maintained consistently allowing for
condensation reactions to occur. Attempting to apply conventional visbreaking
to
Canadian Bitumen is limited due to the propensity for coking and inability of
these systems to manage this issue.
In the first part of US Pat. No. 6,972,085 and in US Pat. No.
7,976,695 an attempt is made to address the desire for a constant and
sustained
application of heat to the crude over an extended period of time .
Essentially, the
heater and the holding vessel are merged into one vessel to create a
continuous
heated bath for the crude. Multiple heating levels are applied to the crude at
various times. This is an improvement over standard visbreaking but does not
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eliminate hot spots within the processed crude, permitting coking due to
temperature peaks above optimal levels for cracking.
Combination of Thermal/Catalytic Cracking and Solvent Deasphaltino
In U.S. Pat. No. 4,454,023 a process for the treatment of heavy
viscous hydrocarbon oil is disclosed, the process comprising the steps of:
visbreaking the oil; fractionating the visbroken oil; solvent deasphalting the
non-
distilled portion of the visbroken oil in a two-stage deasphalting process to
produce separate asphaltene, resin, and deasphalted oil fractions; mixing the
deasphalted oil ("DAO") with the visbroken distillates; and recycling and
combining resins from the deasphalting step with the feedstock initially
delivered
to the visbreaker. The U.S. '023 patent provides a means for upgrading lighter
hydrocarbons (API gravity>15) than Canadian Bitumen but is burdened by the
misapplication of the thermal cracking technology that will over-crack and
coke
the hydrocarbon stream, and by the complexity and cost of a two-stage solvent
deasphalting system to separate the resin fraction from the deasphalted oil.
In
addition, the need to recycle part of the resin stream increases the operating
costs and complexity of operation.
In U.S. Pat. No. 4,191,636, heavy oil is continuously converted into
asphaltenes and metal-free oil by hydrotreating the heavy oil to crack
asphaltenes selectively and remove heavy metals such as nickel and vanadium
simultaneously. The liquid products are separated into a light fraction of an
asphaltene-free and metal-free oil and a heavy fraction of an asphaltene- and
heavy metal-containing oil . The light fraction is recovered as a product and
the
heavy fraction is recycled to the hydrotreating step. Catalytic conversion of
Canadian heavy bitumen (API gravity<10) using this '636 process is a high-
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intensity process that tends to have reliability issues with rapid catalyst
deactivation impacting selectivity and yield.
In U.S. Pat. No. 4,428,824, a solvent deasphalting unit is installed
upstream of a visbreaking unit to remove the asphaltenes from the visbreaking
operation. In this configuration, the visbreaking unit can now operate at
higher
temperatures to convert the heavier molecules to lighter hydrocarbon molecules
without fouling, since the asphaltenes are removed from the product stream
entirely. However, the yield of the bitumen is greatly reduced (by 10-15%)
since
the early removal of the asphaltenes in the process prevents thermal
conversion
of this portion of the crude into a refinable product.
As in U.S. Pat. 4,428,824, U.S. Pat No 6,274,032, disclosed a
process for treating a hydrocarbon feed source comprising a fractionator to
separate the primary crude components, followed by a Solvent Deasphalting
(SDA) unit to work on the heavier crude asphaltene rich component, and a mild
thermal cracker for the non-asphaltene stream. The asphaltene rich stream is
processed in a gasification unit to generate syngas for hydrogen requirements.
Placing an SDA unit upstream of a thermal cracker reduces the overall yield of
the bitumen as refinery feed, since the asphaltene portion of the crude,
comprising up to 15% of Canadian bitumen, is removed from consideration for
inclusion in some format as crude. This loss in product yield is not
compensated
for by the increased cracking in the visbreaker.
In U.S. Pat. No. 4,686,028 a process for the treatment of whole
crude oil is disclosed, the process comprising the steps of deasphalting a
high
boiling range hydrocarbon in a two-stage deasphalting process to produce
separate asphaltene, resin, and deasphalted oil fractions, followed by
upgrading
only the resin fraction by hydrogenation or visbreaking. The U.S. Pat. No.
4,686,028 invention applies visbreaking to a favourable portion of the whole
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, .
crude stream to minimize coke generation. However, PAT '028 is limited by
missing a large part of the crude that could benefit from optimal conversion
and
thus a large portion of the crude does not end up as pipeline product without
the
need of transport diluent.
In U.S. Pat. No. 5,601,697 a process is disclosed for the treatment
of topped crude oil, the process comprising the steps of vacuum distilling the
topped crude oil, deasphalting the bottoms product from the distillation,
catalytic
cracking of the deasphalting oil, mixing distillable catalytic cracking
fractions
(atmospheric equivalent boiling temperature of less than about 1100 degrees
F.)
to produce products comprising transportation fuels, light gases, and slurry
oil.
U.S. Pat. No. '697 is burdened by the complexity, cost, and technical
viability of
vacuum distilling a topped heavy crude to about 850 F and catalytic cracking
the
deasphalted oil to produce transportation fuels.
In U.S. Pat. 6,533,925, a process is described involving the
integration of a solvent deasphalting process with a gasification process and
an
improved process for separating a resin phase from a solvent solution
comprising
a solvent, deasphalted oil (DAO) and resin. A resin extractor with the solvent
elevated in temperature above that of the first asphaltene extractor is
included in
the '925 invention. The asphaltene stream is treated but removed prior to any
thermal conversion eliminating the possibility of obtaining a value uplift
into
useable refinery feedstock. The impact is a reduction in the potential overall
yield of the crude stream.
In U.S. Patent application 2007/0125686, a process is disclosed
where a heavy hydrocarbon stream is first separated into various fractions via
distillation with the heavy component sent to a mild thermal cracker
(visbreaker).
The remaining heavy liquid from the mild thermal cracker is solvent
deasphalted
in an open art SDA unit. The asphaltenes separated from the SDA are used as
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feed to a gasifier. The deasphalted oil is blended with the condensed mild
thermal cracker vapour to form a blended product. As stated with Pat'023
above,
visbreaking faces the challenges of early coke generation. Specifically, the
'686
patent application explains that the intent of this mild thermal cracker is to
crack
the non-asphaltene material exclusively, which is also not practical with
Canadian bitumen. In this application, the mild thermal cracker operates at
elevated pressures unnecessarily increasing coke formation, and thus yield. In
addition, additional energy is required in the distillation and extraction
steps with
most of the separated components being recombined for pipeline transport.
In US Pat #8,048,291, a process is described where the bottoms
from an atmospheric column and/or vacuum column is treated in a solvent
deasphalting unit and then by some form of thermal or catalytic cracking. The
objective of this patent is to reduce the cost of cracking the DA0 stream by
putting an SDA upstream of the cracker. The multiple extraction steps and
operating conditions of the SDA increase the cost of the entire process
offsetting
some of the savings from a smaller cracking unit, with the integrated process
providing a lower overall yield unless significant costs are incurred to add
hydrogen to increase yield. The SDA unit removes the heavy asphaltenes which
comprised over 15% of heavy bitumen streams, thus limiting overall yield to
less
than 85% unless expensive catalytic processes are employed. The overall result
of this process is uneconomic with the limit of feed being processed being
greater than 5 API through the SDA.
Treatment of SDA generated Asphaltene-Rich Stream
In US Patent# 4,421,639 a solvent deasphalting process uses a 2nd
asphalt extractor to concentrate asphaltene material (and recovery of more
deasphalted oil). The concentrated asphalt stream is sent through a heater to
get to 425 F at 18 psia and uses a flash drum and stream stripper to separate
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. .
solvent (in this case propane) from the asphalt stream. Asphalt product, in
liquid
form, is pumped to storage. This arrangement only works if the asphalt rich
stream is liquid at these conditions. It is burdened by plugging if any
appreciably
solid asphaltenes are present as in asphaltene-rich streams like bitumen.
In US Patent# 3,847,751, the concentrated asphaltene product
from the SDA unit is mixed with solvent to transport as a liquid solution to a
spray
dryer. The spray nozzle design and pressure drop dictates the size of liquid
droplets that are formed. The smaller the light hydrocarbon (solvent) droplet,
the
faster it will flash completely to vapour. The smaller the heavy hydrocarbon
(asphaltene) particle the more surface area available for heat transfer to
cool the
heavy droplets down with the goal of producing a dry, non-sticky solid
particle.
Additional cold gas is added to the bottom of the spray dryer to enhance
cooling
by additional convective heat transfer as well as increasing the droplet
residence
time by slowing its descent rate (via upward cooling gas flow) in order to
reduce
the size of the vessel (which tend to be extremely large). This arrangement is
not required if the asphaltene particles that have settled out in the
extractor are in
a solid form in the solvent at the process operating temperature.
In US Patent# 4,278,529, a process for separating a solvent from a
bituminous material by pressure reduction without carry-over of bituminous
material is illustrated. The fluid-like phase comprising bituminous material
and
solvent is reduced in pressure by passage through a pressure reduction valve
and introduced into a steam stripper. The pressure reduction vaporizes part of
the solvent and also disperses a mist of fine bituminous particles in the
solvent.
The concern with this approach is that the remaining asphaltene remains wet
and
sticky and has not enough solvent left to keep the heavy bituminous phase
(with
many solids) flowable.
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In US PAT# 4,572,781 a solvent deasphalting process for
separating substantially dry asphaltenes of high softening point from heavy
hydrocarbon material using a centrifugal decanter to separate a liquid phase
from
a highly concentrated slurry of solid asphaltenes is described. This process
attempts to handle a rich asphaltene stream that has solid particles but is a
highly costly process since the separation of the solids is done through a
solid/liquid separation with additional solvent needed to make the material
flow to
the decanter. Invariably, the separated solid material is still relatively wet
and
needs another drying step to recover the solvent as a vapour. The solvent
vapour needs to be condensed for re-use, another high energy step.
In US Patent# 5,009,772 a method is shown relating to a
continuous, relatively low temperature deasphalting process in which a heavy
hydrocarbon feedstock material and an extraction solvent are contacted, at
elevated subcritical temperatures and superatmospheric pressures, in an
extraction zone to produce a light extract phase and a heavy phase rich in
higher
molecular weight hydrocarbon components, Conradson carbon precursors and
heavy metals. Pat# 5,009,772 comprises continuously effecting a reduction in
the pressure upon the first light extract phase produced within the extraction
zone suggesting there are benefits of operating at less than supercritical
conditions in the SDA unit. However, further improvements in the overall
process
can be used to allow for more heavier crudes to processed in a simpler, less
costly fashion.
In US Patent# 7,597,794, a dispersion solvent is introduced into
the asphalt phase after separation by solvent extraction and the asphalt phase
undergoes rapid phase change in a gas-solid separator and is dispersed into
solid particles while the solvent vaporizes, resulting in low temperature
separation of asphalt and solvent with adjustable size of the asphalt
particles.
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The challenge with flash/spray driers using liquid solvent as the transport
media
is the propensity for the asphaltenes generated in this process to remain
wetted
before, during and after the flash drying phase. In addition, with this
process, the
asphaltene continues to liquefy at elevated temperatures. A wetted asphaltene
sticks to all surfaces and fouls and plugs the equipment readily. The reduced
reliability from using this approach makes this operation costly for heavy
crudes
with high asphaltenic content. Example 6 in the patent uses heavy crude with
an
API of 2 with a resultant overall DA0 yield of 83.5% and solvent recovery of
over
80%. Both these values represent an uneconomic process and can be greatly
improved.
In US Patent #7,749,378, a method is illustrated for transporting
and upgrading heavy oil or bitumen, comprising: diluting the heavy oil or
bitumen
at a production site with a diluent comprising a hydrocarbon having from 3 to
8
carbon atoms to form a mixture; transporting the mixture from the production
site
to a solvent deasphalting unit; deasphalting the mixture in the solvent
deasphalting unit to recover an asphaltene fraction, a deasphalted oil
fraction
essentially free of asphaltenes, and a solvent fraction; separating water and
salts
from the asphaltene fraction, the deasphalted oil fraction, and the solvent
fraction
at the solvent deasphalting unit; and conveying at least a portion of the
solvent
fraction to the production site to dilute the heavy oil or bitumen and form
the
mixture. The process is rightfully limited to crudes above 2 API (2-15 API is
claimed) in this patent since plugging of the extractor invariably results in
low
reliability and the conditions allowed in the process limit overall yield to
<85% of
the total barrel since heavy crudes like bitumen will have asphaltene content
over
15% and these molecules are entirely rejected in this process.
In US Patent# 7,964,090 a method for upgrading heavy asphaltenic
crudes using SDA and gasification is disclosed. Of interest in this patent, a
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stream to a gasifier is generated by mixing a hydrocarbon comprising one or
more asphaltenes and one or more non-asphaltenes with a solvent, wherein a
ratio of the solvent to the hydrocarbon is about 2:1 to about 10;1. The
asphaltene rich stream is transferred out of the SDA to a gasifier as a liquid
stream. The large quantities of solvent used in transport are consumed in the
gasifier, and are downgraded in value to a fuel gas equivalent. Since the
asphaltenes tend to be liquid, using a solvent to transport the material in
the
quantities stated is feasible. For a solid asphaltene, this method would
require
10-20 times more solvent to transport and this quantity of expensive solvent
would be consumed and its value reduced.
SUMMARY OF THE INVENTION
Essentially, an improved process for producing a pipeline-ready
crude and refinery feedstock from heavy crude oils, such as Canadian Oil Sands
bitumen, is described, with said process consisting of: (1) optimal asphaltene
conversion with minimum coke and offgas make in a full bitumen stream within a
reactor to produce a thermally affected asphaltene-rich fraction, a minimum
non-
condensable vapour stream, and an increased refinery-feed liquid stream; (2)
deasphalting said thermally affected asphaltene-rich fraction into a refinery-
feed
liquid stream and a concentrated asphaltene stream; (3) selectively
hydrotreating
specific hydrocarbon components as required for pipeline specification, and
finally blending of all the liquid streams to produce a refinery feed; and (4)
inertial
separation of the concentrated solid asphaltene stream for conversion in a
gasifier, power or asphalt plant.
The bitumen is thermally treated to remove and convert/crack
selected asphaltenes, which are then sufficiently separated in a more
efficient
solvent extraction process, reducing production of coke and isolating
undesirable
contaminants (like metals, MCR, and remaining asphaltenes).
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Considering the relative complexity and high degree of side chains
on Canadian bitumen asphaltenes, under the operating conditions of the
invention disclosed here, the side chains are preferentially cleaved from the
core
asphaltene molecule to make desired vacuum gas oil to light hydrocarbon range
components. Light hydrocarbon includes for example methane, ethane, and
propane. The remaining thermally affected polyaromatic asphaltene cores remain
solid at elevated temperatures and pressures above operating conditions and
thus separate more readily than non-thermally affected asphaltenes resulting
in
improved separation processes, such as solvent deasphalting (50) and inertial
separation (60).
Further, the heavier hydrocarbons in the bitumen are also mildly
cracked to vacuum gas oil, gasoline and distillate boiling range components,
all
desirable for separation and conversion in refineries. Any major deviations in
temperature and heat flux within the bitumen pool in the reactor will lead to
coking and increased gas yield and a reduction in the overall crude yield of
the
original bitumen, and reduced reliability of the operation, increasing the
operating
cost of the facility.
.= The invention provides an improved apparatus and
method for
producing a pipeline-ready and refinery-ready feedstock from heavy, high
asphaltene crudes (for example, Canadian bitumen) and feedstocks, with utility
for any virgin or previously processed hydrocarbon stream, the process and
apparatus comprising a pre-heater for pre-heating a process fluid to a design
temperature at or near the desirable operating temperature of a reactor;
moving
the process fluid into a reactor for conversion of the process fluid by
controlled
application of heat to the process fluid in the reactor so that the process
fluid
maintains a substantially homogenous temperature throughout the reactor to
produce a stream of thermally affected asphaltene-rich fractions, and a stream
of
liquid hydrocarbon vapour with minimal non-condensable vapour. The stream of
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vapour is separated into two further streams: of non-condensable vapour, and
of
light liquid hydrocarbons. The thermally affected asphaltene-rich fraction is
first
mixed using a shear mixer, then is deasphalted using a single-stage solvent
extraction process into streams of deasphalted oil liquid and concentrated
asphaltene, respectively. The deasphalted oil liquid and the light liquid
hydrocarbons produced in the processes are blended to form a pipeline and
refinery-ready feedstock. The concentrated asphaltene is processed in an
inertial separation unit to create a dry solid asphaltene by-product.
A sweep gas can be deployed in the reactor, and can be preheated
to provide a heat flux source other than the reactor's heaters; the sweep gas
may
also assist in the removal of reactor vapour products.
Deasphalting is achieved using a minimum of one extraction step
(more steps may be used) and a low pressure stripper at conditions outside any
open-art solvent extraction process. Since the initial process fluid has been
thermal-affected, the heavy asphaltene-rich fractions can be further separated
using a shear mixer and a lower complexity single stage extraction process
using
a combination of lower solvent-to-oil ratios, temperatures and pressures than
typically found in similar upgrader operations. Even further improved solvent-
extraction performance, using even lower overall solvent to oil ratios and
improved DA0 yield can be achieved by further concentrating the asphaltene
rich
fraction before a final extraction step. The process improves on open-art
solvent
deasphalting utilizing an additional solvent extraction column (rinse column)
operating on the asphaltene-rich stream from the primary solvent extraction
column to increase pipeline crude recovery and quality.
The SDA process may allow for some portion of the heavy
asphaltene-rich hydrocarbon stream to be recycled and blended with the fresh
feed to the reactor.
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The resulting concentrated thermally-affected asphaltenes can be
successfully processed in an inertial separator such as a centrifugal
collector or
settling chamber to generate a dry, solid asphaltene by-product.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the drawings wherein like reference numerals indicate
similar parts throughout the several views, several aspects of the present
invention are illustrated by way of example, and not by way of limitation, in
detail
in the figures, wherein:
Fig. 1 is a process diagram for forming a pipeline transportable
hydrocarbon product from a heavy high asphaltene hydrocarbon feedstock; and
Fig. 2 is a process diagram pertaining specifically to a cracking
process and liquid separation process and a solids separation process; and
FIG. 3 depicts an illustrative application of an integrated mild
thermal cracking and improved solvent deasphalting process with appropriately
placed shear mixing devices within an existing upgrader or refinery with a
vacuum and/or coking unit according to one or more embodiments described.
FIG. 4 depicts a specific illustrative application from FIG. 3 of an
integrated mild thermal cracking and improved solvent deasphalting process fed
a vacuum bottoms stream from an existing upgrader or refinery with the various
products from the integrated cracker/SDA sent to hydrocracking, residual
hydrocracking and gasification units according to one or more embodiments
described.
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DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
The detailed description set forth below in connection with the
appended drawings is intended as a description of various embodiments of the
present invention and is not intended to represent the only embodiments
contemplated by the inventor. The detailed description includes specific
details
for the purpose of providing a comprehensive understanding of the present
invention. However, it will be apparent to those skilled in the art that the
present
invention may be practiced without these specific details.
It is to be understood that other aspects of the present invention will
become readily apparent to those skilled in the art from the following
detailed
description, wherein various embodiments of the invention are shown and
described by way of illustration. As will be realized, the invention is
capable for
other and different embodiments and its several details are capable of
modification in various other respects, all without departing from the spirit
and
scope of the present invention. Accordingly the drawings and detailed
description are to be regarded as illustrative in nature and not as
restrictive.
Figure 1 is a process flow diagram depicting a process 10 for
forming a hydrocarbon product 160 from a hydrocarbon feedstock 12, where the
final hydrocarbon product 160 has sufficient characteristics to meet minimum
pipeline transportation requirements (minimum API gravity of 19, and 350 cSt
at
ambient temperatures) and is a favourable refinery feedstock. A process fluid
14 formed from a feedstock 12 of heavy high asphaltene hydrocarbon can be
routed through a pre-heater 20 to heat the process fluid 14 to a desired
temperature level before the resulting stream 21 is routed to a reactor 30
where
the process fluid 14 is controlled and maintained while it undergoes a mild
controlled cracking process. After the mild cracking process, a light top
fraction
32 can be routed from the reactor 30 to a gas liquid condensing separator
process 40 and a heavy bottom fraction 34 can be routed to a high performance
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solvent extraction process 50. Some of the outputs 44 from the gas liquid
=
separation process 40 can be blended with some of the outputs 52, 54 of the
simplified solvent extraction process 50 to result in a hydrocarbon product
160
that has sufficient physical characteristics to enable it to meet the required
pipeline transport criteria without having to mix the final hydrocarbon
product 160
with diluents from external sources, or requiring much reduced volumes of such
diluent.
The feedstock 12 can be a heavy high asphaltene hydrocarbon
(virgin or a previously processed stream), such as the heavy high asphaltene
hydrocarbon obtained from a SAGD (steam assisted gravity drainage) process,
for example Canadian Oil sands bitumen, or from any other suitable source of
heavy high asphaltene hydrocarbon. In one aspect, the feedstock 12 can have
an API gravity in the range of 0 to 14.
In one aspect, a recycled portion 70 of the resin stream 54 output
from the high performance solvent extraction process 50 can be blended with
the
incoming feedstock 12 to form the process fluid 14 that passes through process
10. The resin stream may be added to the process fluid in instances in which
further crude yield, and/or lighter crude, and/or asphaltene suppression is
desired
in order to meet treated product characteristic targets. The resin recycle
provides the operator with flexibility, through an adjustable flow parameter,
to
meet production specifications, and allows the plant to handle feedstock
variations robustly.
The resin product 54 from the solvent extraction process 50 will
typically have a relatively low API gravity. In one aspect, the API gravity of
the
resin product 54 can have an API gravity between 0 and 10. Depending on the
characteristics of the feedstock 12 and the amount of resin product 54 blended
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with the feedstock 12, the resulting process fluid 14 can have a range of
characteristics and particularly a range of API gravities.
The process fluid 14 (obtained entirely from the feedstock 12 or
formed as a blend of feedstock 12 and resin product 54 from the solvent
extraction process 50) can be routed to the pre-heater 20 where the process
fluid
14 can be heated to a desired temperature as it passes through the pre-heater
20 before being routed to the reactor 30 to undergo mild thermal cracking.
Reactor 30 maintains a consistent fluid temperature through a uniform
application of heat through-out the reactor to allow for mild thermal cracking
to
occur without coking being a concern or detrimental to the operation and/or
performance of the reactor.
In one aspect, the pre-heater 20 will heat the process fluid 14 to a
temperature between 675-775 F before the process fluid 14 is introduced into
the
reactor 30.
In the reactor 30, the process fluid 14 (heated to between 675-
775 F by the pre-heater 20) undergoes a mild controlled cracking process.
Appropriately located heaters are provided in this reactor 30 to maintain the
desired constant temperature generated in pre-heater 20 and to apply uniform
heat flux for the fluid 14. The heaters provide heat through any source
readily
available (electric, heat transfer fluid, radiant etc.). The reactor 30 can be
operated in a manner, through optimizing primarily five inter-related process
variables (Temperature, Pressure, Residence Time, Sweep Gas and Heat Flux),
so as to reduce or even prevent coke from forming during the reaction, and
minimizing gas production, while also providing optimal conversion of the part
of
the asphaltene portion of the heavy high asphaltene hydrocarbon to refinery-
ready feedstock components.
WSLega1\048127\00093\0553014v6 - 17 -
CA 02764676 2013-04-11
The first and second variables involve applying a uniform heat flux
between 7000-12000 BTU/hr sq.ft to the entire pool of process fluid in the
reactor
and maintaining a single operating temperature in the reactor between 675-
775 F. This may be achieved by the presence of appropriately sized and located
The third reactor variable, residence time, can be between 40-180
The fourth reactor variable, operating pressure, can be maintained
at near atmospheric pressure, in any case to be less than 50 psig, with
standard
pressure control principles used for consistent performance. The pressure
range
is controlled on the low end to prevent excessive, premature flashing of
The fifth reactor variable, hot sweep gas 36, in the same
temperature range as the process fluid (675-775 F) 21, is added to the process
fluid 14 in the reactor 30 in the range of 20-80 scf/bbl.
20 The sweep gas 36 can be natural gas, hydrogen, produced/fuel gas
from the process, steam, nitrogen or any other non-reactive, non-condensable
gas that will not condense to a liquid in the reactor environment.
Sweep gas in the dosage of 20-80 scf/bbl of feed is provided to
remove the "lighter" hydrocarbon products (i.e. methane to <750 F boiling
point
WSLega11048127\00093\85530144 - 18 -
CA 02764676 2013-04-11
minimum of secondary cracking which could increase gas make and potentially
increase olefinic naphtha/distillate production.
The sweep gas may also allow the reactor to operate closer to the
desired operating pressure (<50 psig) and temperature. The sweep gas 36 can
also be used to provide additional heat and/or mixing to the process fluid 14
in
the reactor 30.
As discussed with respect to Figures 1 and 2, the heat energy
stream 36, for reactor 30 is uniformly (7000-12000 BTU/hrsq.ft) applied
throughout the hydrocarbon residence time (40-180 minutes) in the reactor at
the
desired temperature (675-775 F) and pressure (less than 50 psig) to minimize
any local peak fluid temperatures which can initiate coking, and thereby
allowing
an increased thermal transfer of heat at a higher bulk temperature improving
the
conversion of hydrocarbons within reactor 30. At these operating conditions,
the
reaction kinetics favour optimum conversion of the asphaltenes that
preferentially
cleaves the outlying hydrocarbon chains creating desirable hydrocarbons (VG0
and diesel range hydrocarbons) for the refiner without causing coking or
increased gas production in the reactor. As an example, Table 1 illustrates
different configurations of asphaltenes for different types of crudes. The
proposed operating conditions of reactor 30 factor in the relative complexity
and
high degree of side chains on different crudes.
WSLegaR048127\00093µ8553014v6 - 19 -
CA 02764676 2012-01-17
sN
C113
cH., .. ((
,
= -
,
s >
71' j.
013 NII
r
r_ ---,
113C (
)-
i
-rar
A
Table 1 ¨ Average molecular structures representing asphaltene molecules from
different sources: A, asphaltenes from traditional heavy crudes; B,
asphaltenes
from Canadian bitumen (Sheremata et al., 2004).
Each variable may be changed independently, within the ranges
suggested, based on the quality of feedstock provided or based on the quality
of
output desired. Since the 5 noted process variables are inter-related, a multi-
variable process control scheme with a prescribed objective function (for
example maximum yield to meet minimum product specifications) will be
beneficial to ensure the process operates at an optimal point when any one of
the variables is changed or the feed/product situation or goal is altered.
Once the process fluid 14 has remained in the reactor 30 for a
sufficient amount of time so that the characteristics of the outputs of the
reactor
30 reach desired qualities, a light overhead fraction 32 and a heavy bottoms
fraction 34 can be removed from the reactor 30.
The light overhead fraction 32 of the output from the reactor 30 can
contain non-condensable vapor products, light liquid hydrocarbon and heavier
liquid hydrocarbon. The vapor products can be vapors released from the
- 20 -
WSLega1\048127\00091\7461414v3
CA 02764676 2013-01-21
process fluid 14, such as sour gas, while undergoing thermal cracking, as well
as
introduced and unconverted or unused sweep gas 36 that has passed through
the reactor 30.
The overhead liquid fraction 32 will have a much higher API gravity
than the bottom fraction 34. For example, the overhead liquid fraction 32
could
typically have an API gravity of 26 or greater. The overhead fraction 32 can
be
directed to a gas liquid separation unit 40, which can comprise a cooler and
separation drum, as an example, in which a portion of the overhead fraction 32
that is a condensable liquid product containing naphtha and heavier
hydrocarbons can be separated from the gaseous components of the overhead
fraction 32. An off-gas line 43 containing undesirable gases such as sour gas,
can be provided at the separation drum for those gases to be disposed of,
recycled, or subjected to further treatment.
One or more liquid hydrocarbon streams can be produced from
separation drum. Stream 44, a heavier hydrocarbon than stream 43, can be sent
to product blending, while stream 43 can be considered for further bulk hydro-
treating prior to product blending.
The bottom fraction 34 can contain hydrocarbons, and modified
asphaltenes. Although the characteristics of the bottom fraction 34 taken from
the reactor 30 will vary depending on the process fluid 14 input into the
reactor
and the reactor's operating parameters, in one aspect the bottom fraction 34
can have an API gravity ranging between -7 and 5.
Controllable process variables allow an operator to vary the
performance of the reactor 30 to meet the needs of the final product based on
25 changing characteristics of the incoming process fluid 14.
- 21 -
WSLega11048127100093\8566603v1
CA 02764676 2013-04-11
The controllability of the five inter-related variables, residence time,
sweep gas, heat flux, temperature and pressure in the reactor 30 allow an
operator to vary the performance of the reactor 30.
In this manner, when the characteristics of the feedstock 12 are
changed either as different fresh feed or more or less resin recycle 70, the
five
inter-related process variables can be optimized to avoid the production of
coke
and minimize the production of non-condensable vapors that are produced in the
reactor 30. For example, the operator can vary the residence time of the
process
fluid 14 in the reactor 30 based on the characteristics of the process fluid
14 to
obtain the desired yields and/or quality of the outputs 32, 34. Alternatively,
the
operator can vary the sweep gas, temperature or pressure to achieve similarly
tailored outcomes. The process variables are inter-related and the
minimization
of coke and avoidance of excess gas make is challenging and is best determined
by pilot operations, which may be done without undue experimentation.
The bottom fraction 34 from the reactor 30 can be fed to a
simplified solvent extraction process 50 that can produce a thermally affected
asphaltene stream 58, an extracted oil stream 52 and a resin stream 54. The
reactor 30 is operated in a manner that significantly limits and even prevents
the
formation of coke and reduces gas production while converting asphaltenes into
more suitable components for downstream processing. Consequently, modified
asphaltenes and other undesirable elements remain in the bottom fraction 34
that
is removed from the reactor 30.
To maximize the recovery of the desirable refinery feedstock crude
the undesirable elements that remain in the bottom fraction 34, the bottom
fraction 34 from the reactor 30 must be further treated using, for example, a
high
simplified solvent extraction process 50. The treatment of the bottom fraction
34
by solvent extraction process 50 allows the reactor 30 and the solvent
WSLega1\048127\00093\85530140 - 22 -
CA 02764676 2013-04-11
extraction process 50 to be used in conjunction to produce a suitable full
range
refinery feedstock crude.
The solvent extraction process 50 can comprise any suitable
solvent extraction process. In one aspect, it can be a three stage super-
critical
solvent process that separates the asphaltenes from the resins in the bottom
fraction 34. A preferred embodiment is a shear mixer, a simple asphaltene
extractor, a solvent/DA stripper and an inertial separation unit. The output
of
the solvent extraction process 50 can be an asphaltene stream 58, an extracted
oil stream 52 and a resin stream 54. The asphaltene stream 58 is typically
undesirable and is removed from the process 10. The extracted oil stream 52
can be of a relatively high quality, with an API gravity range of 9 to 15. The
resin
stream 54 is typically of a lower quality than the extracted oil stream 52,
with an
API gravity lower than the extracted oil stream 52. In one aspect, the resin
stream 54 can have an API gravity in the range of 0 to 10 API gravity.
The extracted oil stream 52 and the resin stream 54 from the
solvent extraction process 50 can be blended along with the liquid product
stream 44 obtained from the liquid gas separator 40 to form a final
hydrocarbon
product 160 meeting the specifications of the pipeline and/or refinery-ready.
In
one aspect, this final hydrocarbon product 160 would have an API gravity
greater
than 19. Typically, the final hydrocarbon product 160 would have a viscosity
of
350 CentiStokes ("cSt") or less.
The resin stream 54 is typically of a lesser quality than the
extracted oil stream 52. The recycle portion 70 of the resin stream 54 can be
blended with the feedstock 12 to be reprocessed in order to form the final
hydrocarbon product 160. As a result, this recycling portion of the resin
stream
will improve the quality of the final hydrocarbon product 160.
WSLegaR048127\00093\8553014v6 - 23 -
CA 02764676 2013-01-21
In one embodiment, the asphaltene stream 58 is fed to an inertial
separation unit 60 to produce a solvent vapour stream 62 and a dry solid
asphaltene stream 61. The inertial separation unit 60 will be described in
more
detail hereinbelow.
In another aspect, in figure 2, the optimal solvent deasphalting and
solid separation scheme is illustrated when integrated with reactor 30
operated
with the five inter-related variables set accordingly for maximum yield. The
feedstock 12 is fed to an integrated mild thermal cracker 20,30,40 which
generates at least stream 44, a heavier hydrocarbon than stream 43, and bottom
fraction 34, as described above with respect to figure 1. Solvent 1 may be
added
to bottom fraction 34 before it is sent to an SDA pre-heat unit 25 to generate
stream 21. Stream 21 is sent to a shear mixer and/or rapid/complete mixer 35
to
produce stream 31, which is then fed to a single asphaltene extractor 50. A
solvent 3 may be added to the extractor 50 while stream 31 is processed
therein.
The shear mixer 35 and the single asphaltene extractor 50 are provided to
separate the solid asphaltenes in stream 58 from the oil and solvent, stream
51.
Because of the thermally affected asphaltenes created in reactor 30, the
solvent
extraction can occur in one stage and can be effective at a solvent to oil
mass
ratio of up to about 2.5:1 and at operating conditions well below the critical
point
for the solvent. As a result of the low energy/intensity single stage
extraction, a
single low pressure solvent stripper processing stream 41 is economical and
effective to separate the product deasphalted oil 52 and the recovered solvent
as
stream 101. Stream 41 may be separated into stream 101 and oil 52 by adding
solvent 2 and/or 51 and heating 90 the resulting stream to generate a stream
91
for processing in a solvent stripper unit 100. In one embodiment, prior to
heating
90, stream 41 may be optionally heated 70 to produce stream 71 for processing
in a resin extractor and stripper 80. The resin extractor and stripper 80
outputs a
stream 81 for subsequent heating 90 and processing by solvent stripper 100,
and
the resin stream 54 as described above with respect to figure 1. Stream 42,
the
- 24 -
WSLega11048127\00093\8565603v1
CA 02764676 2013-04-11
concentrated asphaltene solid stream produced by asphalt extractor 50, is
processed in an inertial separator 60 separating a solvent vapour stream 62
and
a dry solid asphaltene stream 61. Stream 62 is condensed using a solvent
condenser 110 to produce stream 111, which is fed to a solvent recovery unit
120. The recovered solvent 122 is mixed with stream 1 for reuse in the
process.
The dry solid is sent to dry solid storage 130 or otherwise handled. The
inertial
= separation unit 60 separates the asphaltene solids from the remaining
solvent in
stream 42 using a combination of forces such as centrifugal, gravitational,
and
inertial. These forces may move the asphaltene solid to an area where the
forces exerted by the gas stream are minimal. The separated solid asphaltene
may be moved by gravity into a hopper where it is temporarily stored. Unit 60
can be either a settling chamber, baffle chamber or centrifugal collector; a
device
that provides inertial separation of solid and gas. Centrifugal collectors can
either be single or multi-staged cyclones. In the event the SDA unit 50 is
overly
effective in separating the asphaltenes from the resin, DAD and solvent,
stream
42 can be injected with suitable low molecular weight gas (ex. Natural gas, or
nitrogen) to provide pneumatic conveyance to the asphaltene solids that
otherwise would be provided by flashing remaining process solvent in the line.
A
pneumatic conveying system may transport solids up to approximately 50 mm
particle size. The solid must be dry, with no more than 20% moisture and not
sticky. The thermally-affected asphaltene solids meet the above criteria and
thus
the process benefits from the ability to use an inertial separation unit, 60.
1
To increase overall recovery of product hydrocarbon from reactor
and reduce solvent circulation rates, a simplified solvent extraction process
25 may optionally include a supplemental extraction process 55, with a
second
shear mixer and/or rapid/complete mixer 235. For example, stream 42 from
extractor 50 is fed to shear mixer 235 to generate a stream 231 for processing
in
the second extractor 55. Solvent 3 may be added to stream 42
- 25 -
WSLega1104812710009318553014v6
CA 02764676 2013-01-21
prior to entering shear mixer 235 and may also be added to extractor 55 while
processing stream 231. Extractor 55 outputs asphaltene stream 58 which may be
processed by the inertial separator 60 in a similar manner as stream 42 as
described above. Solvent 3 and transport gas 4 may be added to stream 58 prior
to the inertial separation process 60. The additional solvent extraction step
on the
asphaltene-rich stream by the second extractor 55 uses standard liquid-liquid
=
extraction with the same solvent used in the primary extractor. The placement
of
this standard liquid-liquid column on the asphaltene-rich stream may be
beneficial since the solvent to oil ratio can be economically increased within
this
column up to 20:1 to increase the recovery of deasphalted oil, while the
overall
solvent use is reduced. Overall solvent use to achieve high hydrocarbon
recovery in stream 52 can be 25% less than using comparable open art
processes. The result is a significant reduction in energy consumption
compared
to a state of the art 3-stage extraction process. The resulting asphaltene
stream
58 can be processed in a 20% smaller asphaltene separation unit 60. The core
portion of the remaining concentrated thermally-affected asphaltenes are solid
even at elevated temperatures (above 7000F) with the side hydrocarbon chains
removed, resulting in less volume for the asphaltene separation unit to
handle.
In addition, the modified nature of the asphaltenes provides for the
opportunity
for more effective metals reclamation and better feedstock for a clean energy
conversion technology (eg. gasification, catalytic gasification, oxy-
combustion for
enhanced SAGD production).
Process 10 in figure 1 provides a crude feedstock that is pipeline
compliant and is optimal for high conversion refiners. Stream 160 has low
metals
- 25a -
WSLega1\048127\00093\8565603v1
CA 02764676 2012-01-17
. ,
(<20 wppm Ni+V), low asphaltenes (<0.3 wt%), a very low TAN number (<0.3 mg
KOH/mg), no diluent, and is high in VGO range material (30-50% of crude). For
high conversion refiners (>1.4:1 conversion to coking), the distillation
quality of
the crude produced in stream 160 will improve utilization of the highest
profit-
generating units while filling out the remaining units. Table 2
shows the
percentage of each boiling range material that comprises a barrel of oil for
various representative heavy oil crude streams in comparison to stream 160 of
process 10. The "non-upgraded" feedstocks (dilbit= diluted bitumen, and WCS=
Western Canada Select ) have more vacuum heavy residue (950+oF material),
over 35% of the total barrel, requiring intense conversion and more light
material
to transport (C5's) to the refinery than refiners can profitably refine to
transportation fuels. The full upgraded/produced refinery-ready feedstock
(SSB=
sweet synthetic blend) on the other hand has essentially no vacuum residue or
light material (C5's). It is not balanced and thus has volume limitations with
refiners. Refiners have developed operations that process an overall well-
balanced feedstock comprising of 10-25% vacuum residue, 20-50% gas oils
(HVGO = heavy vacuum gas oil, LVGO = light vacuum gas oil, AGO
=atmospheric gas oil), a 40-60% gasoline to diesel range material. As shown in
table 2, Stream 160 compares favourably to other heavy conventional well-
balanced crudes (ANS = Alaska North Slope, WTI = West Texas Intermediate,
MSO = Medium Sour (Midale)) with hydrocarbon composition in the same range
as these other heavy conventional crudes.
- 26 -
WSLega1\048127\00091\7461414v3
CA 02764676 2013-01-21
Stream 160
% of barrel (Process 10) Dilbit ANS WTI MS0 WCS
SSB
C5s 0.0 6.0 4.0 4.0 4.0 6.9
1.5
Naphtha/Gasoline 8.7
16.0 26.6 31.0 18.5 12.3 20,1
Kerosene 15.5 5.0 13.4 20.0 18.3 10.9
23.7
Diesel 15.1 5.0 11.3 10.6 18.8 7.5
15.5
AGO/Fuel 011 16.1 6.0 9.1 73 6.2 8.9
12.0
INGO 15.1 7.5 7.7 7.3 6.6 6.9
17.8
HVGO/Bunker C 12,7 8.5 8.3 7.3 7.0 10.1
9.0
Vacuum Residue 16.9 46.0 19.7 12.5 20.6
36.5 0.5
Table 2 - Distillation analysis for various crudes including Process 10
Product
The combination of reactor 30, high performance solvent extraction
process unit 50, and inertial separation unit 60, exhibits a reduced process
complexity. This may be expressed as a Nelson complexity index value of 4.0-
4.5, significantly less than 9.0-10.0 for a coking and/or hydroprocessing
scheme.
Another illustration of improved performance is the reduced energy requirement
of 3.93 GJ/tonne feed when compared to a delayed coking process that requires
an energy input of 4.70 GJ/tonne feed to operate. This is a 16.4% reduction in
energy intensity compared to a delayed coking process. This corresponds to a
specific greenhouse gas (GHG) output of 0.253 tonne CO2/tonne feed for the
Delayed Coking process and 0.213 tonne CO2/tonne feed for the proposed
process. On a product comparison basis, the energy reduction is approximately
25-27% versus a coking process.
When compared to a coking upgrading process and standard
reactor and solvent extraction process, process 10 provides a significant
- 27 -
wst.eg8m48,27\0009318565603v1
CA 02764676 2012-01-17
improvement in yield by minimizing by-products (Coke and non-condensable
hydrocarbons) as noted in Table 3.
Volume `1/0 Mass %
Coking 80-84 78-80
Standard reactor/solvent 86 80-82
extraction process
Process 10 89-91 84-86
Table 3 ¨ Product (stream 60) yield comparison
With the lower complexity of process 10, another benefit, attributed
to lower operating temperatures and pressures, is the lower capital cost. Less
equipment is needed, and the flange rating that can be used is right below the
"break-point" where materials specifications change due to pressures and
temperatures involved, increasing costs. Considering the high sulfur content
and
TAN rating of the material, 304L/316LSS material is a suitable choice for
reliability. For this metallurgy, class 300 piping and flanges, as an example,
can
handle up to 400 F and 415 psig (source: ASME/ANSI B16.5 1988/2009
specification). The SDA unit will operate at maximum 400 F and 400 psig, so
Class 300 can be specified. When comparing to open-art SDA processes, a
higher piping/flange class like class 600 will be required to deal with the
higher
operating temperatures and pressures of those other processes. The overall
capital cost savings will be in the 20-30% range for process 10 versus open-
art
SDA configured processes, with Class 600 flanges, for example, costing 8 times
the price of Class 300 flanges.
- 28 -
WSLegah 048127 \ 00091 \7461414v3
CA 02764676 2013-01-21
As well as being suitable for new grassroots facilities, figure 3
shows an illustrative application of the disclosed integrated controlled
thermal
cracker and improved SDA of this invention to an existing upgrader. The
proposed integrated process, reactor 30, simplified SDA 50, and asphaltene
recovery 60, can be placed upstream of a refiner's/upgrader's coking unit. The
benefit to a refiner/upgrader is the ability to debottleneck the vacuum and
coking
unit and accept more heavy crude to the unit. More barrels processed on
existing equipment equates to larger profits and economic returns on invested
capital. In addition, with a higher quality material being sent to the coking
unit,
300, the operating severity can be decreased, increasing the life of the coker
by
increasing the cycle time for the coker (from 12 to 24 hours), and producing
less
gas and coke and more product. Capital costs to replace equipment can be
delayed and an increased yield can be realized (approx. 2-3%). The solid
asphaltenes captured in the SDA have a readily available disposition, stream
302, the existing coke gathering and transport systems making the addition of
the
proposed integrated process more cost effective and highly profitable.
Stream 12 can be the bottoms streams from an atmospheric
column, vacuum column, or a catalytic cracking unit, noted as unit 200 in
Figure
3. In Figure 3, stream 12 is fed into integrated cracker 20, 30, 40 to produce
at
least stream 44, a heavier hydrocarbon than stream 43, and bottom fraction 34,
all as described above with respect to figure 1. Stream 34 may have solvent 1
added thereto prior to SDA pre-heating 25 to generate stream 21. Stream 21 is
sent to shear mixer 35 and the resulting stream 31 undergoes SDA process
50,55,60,100,235. The integrated cracker 20,30,40 and SDA process
50,55,60,100,235 produce a DAO stream 52 that can be further processed into
transportation fuels of stream 401 in a hydrocracking and hydrotreating
complex
unit 400. The integrated cracker and SDA process also can produce a resin
quality stream 54 that can be sent to a coking, FCC (fluidized catalytic
cracking)
and/or an asphalt plant 300 for further processing into finished products.
Unit
- 29 -
WSLega1104812710009318565803v1
CA 02764676 2013-01-21
300 produces a hydrocarbon stream 301, which can be sent to unit 400 for
further processing, and a coke stream 302. As stated previously, the solid
asphaltenes generated as stream 61 can either be mixed with the coke 302
generated in unit 300 or sent off-site for further processing (energy
generation
and/or sequestration).
As an example, Figure 4 shows a specific embodiment for a new
design or revamp opportunity for a refinery and/or upgrader. Unit 200 is a
vacuum unit and the bottoms stream 12 is sent to the integrated cracker/SDA
process, units 20,30,40,50,55,60,100,235.
Integrated cracker 20, 30, 40
produces at least stream 44, a heavier hydrocarbon than stream 43, and bottom
fraction 34, all as described above with respect to figure 1. Stream 34 may
have
solvent 1 added thereto prior to SDA pre-heating 25 to generate stream 21.
Stream 21 is sent to shear mixer 35 and the resulting stream 31 undergoes SDA
process 50,55,60,100,235. The DA stream 52 generated by the SDA process is
sent to the hydrocracking and hydrotreating unit 400, along with stream 205
from
the vacuum unit 200 and stream 44 from unit 40, to produce transportation
fuels
stream 401. A resin stream 54 is produced from unit 50, and sent to a residue
hydrocracking unit 500, which produces a hydrocarbon stream 501 and an
asphaltene stream 502. With less asphaltenes, that are highly exothermic when
reacted, sent to unit 500, the residue hydrocracker can run at higher
conversions
(+8-15%) producing more material as final transportation fuel product. The
solid
asphaltene stream 61 from unit 60, along with stream 502 from the residue
hydrocracking unit 500, can be sent to the gasification unit 600 for hydrogen
generation.
As in figure 3, the benefits of adding the integrated unit in figure 4
may include: maximum yield of incoming crude to plant debottlenecking, if
existing, or reduction of coking unit size; debottlenecking, if existing, or
reduction
- 30 -
WSLega1\048127100093\8585603v1
CA 02764676 2013-04-11
of residue hydrocracking size; debottlenecking, if existing, or reduction of
gasification unit size; overall carbon footprint reduced for complex.
The integrated process in figure 2 can also can help sweet, low
complexity (hydro-skimming) refiners take heavier, cheaper crudes which are
more readily available, and thus reposition assets to capture more value. The
integrated process can be placed at the front of the refinery to provide the
initial
conditioning of the heavier crude.
OPERATING CONDITIONS COMPARISON
The novel arrangement and features of the integrated process of
the invention may provide an opportunity to operate in a region not previously
possible in any specific prior art process thereby creating a technically
feasible
and economically favourable/superior solution for treating heavy high
asphaltene
hydrocarbons
WSLe9a1\04812710009318553014v6 - 30a -
CA 02764676 2013-04-11
down to API's of O. With DAO volume yields in the 89-91% range and with
solvent losses less than 2%, this low complexity integrated process, resulting
in
= low operating and capital costs, creates an economical (based on rates of
return)
solution to create a pipeline ready and refinery feedstock. Table 4 provides a
comparison of some representative existing patents with the present invention.
The items in bold indicate conditions that directly limit or disadvantage the
prior
art when compared to process 10. None of the compared technologies achieve
the same yields as the illustrated process for heavy high asphaltene
hydrocarbon
feeds in the 0 to 7 API density range. The comparison includes integrated
cracker and SDA units, and also SDA only schemes. Since this invention
borrows some concepts of a thermal cracker process outlined in US PAT#
7976695 for part of its operation, a comparison to thermal cracker processes
is
not provided. Of note in Table 4, the unique combination of operating
conditions
for the thermal cracker allows for a simplification of the SDA that can run
with a
unique combination of operating conditions and the use of an inertial
separator
handling strictly asphaltene solids and solvent vapour.
- 31 -
WSLega11048127\00093185530144
Zhao Zhao _ Zheng et al Lutz KBR KBR-Rose Kerr-
McGee
Conditions MEG HI-Q 7597794 , 7597794
2007/0125686 4454023 8048291 7749378 5009772
Example 6
Arrangement Cra cker to SDA SDA only
SDA only Cracker to SDA Cracker to SDA SDA to cracker SDA only
SDA only
Thermal Cracker
Style controlled - Visbreaker ,
Visbreaker Visbreaker -
-
-
.
Feed to Thermal Cracker (API) 0-9 - - ? ? -
- -
Temperature of reactor (oF) 675-775 - 662-932
850-920 _
-
-
.
Pressure of reactor (psig) 0-40 - - 43-2175 250
- -
Residence Time (min) 40-180- - 60-360 16-26
- -
Sweep Gas (scf/bbl) 20-80- - - , -
- - 0
_
Heat Flux in Reactor (BTU/hr sqft) 7000-12000- - -
- - - - o
N.)
Gearhart -4
,
o)
SDA 4239616
o.
.
cn
Feed to SDA (API) -5 to 0 2.00 2+ ? , ? ( O, VB coke)
5-30 2-15 ? --:
_
o)
320-400;
N.)
o
Asphalt ext temp (oF) Tc-(40-130) 374.00 176-482 50-392
200-550 TC+(60-270)tt <450o F Tc-(41-68) ,
N.)
1
200-400;
o
1-,
asphalt ext press (psig) Pc-(40-240) 580.00 435-1450
29-1450 125-900 Pc+(0-100)* 275-1000 Pv to >Pc 1
1-,
Solvent choice C6-C7 C6 C4-C6 C3-05 C3-C9 C3-
C7 C3-C8 C3-C6
solvent to oil ratio _ 2-4:1 M 4.65:1 M _ 1.72-7.02:1 M 3-
12:1 V 2-20:1 M 2-100:1 1-10:1 M 4-20:1 V
Extraction steps in SDA min. 1 2/3 2/3 ? ?
2/3 2/3 min 3 .
_
DAC' Yield (%) 89-90 62/83.5 62/83.5 ? ? ?
? ?
Solvent Recovery(%) over 98% over 80% _ over 80% ?
? ? ? ?
Table 4 ¨ Comparison of Operating Conditions
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With this integrated process, crudes in the API range of 0-12+ can
be processed reliably. In addition, the SDA unit 50 can accept feeds with an
API
in the range of -5 to 0 reliably. The use of sweep gas (not used in other
similar
processes), a uniform heat flux (not maintained in other processes), low
operating pressures and temperatures allow for mild, favourable reactions to
shift
heavier hydrocarbons to the light gas oil range suitable for pipeline
transport
along with the existing hydrocarbons in this range. Minimal coke formation,
and
light gas formation keeps a majority of the hydrocarbons (>90% of crude
barrel)
as desireable product. Asphaltenes have also been converted from "sticky"
molecules to "crunching" molecules. The modified asphaltene rich stream, at
API
densities of -7 to 0, can be processed in a simplified SDA process with a
novel
combination of operating conditions. A single extraction step and a low
pressure
solvent stripper with an inertial solids separator may be all that is needed
to
obtain the stated high yields. As shown in Table 5, the solvent to oil mass
ratio
can be in the range of 2 to 4 : 1 for preferred solvents in the C6 and C7
range.
The temperature in the single extraction column is well below critical, as is
the
pressure. At these low operating conditions, energy use is greatly reduced,
and
only a single low pressure stripper is needed. There is a lot less physical
equipment of less expensive materials and configurations required, making the
overall investment cost lower than other concepts.
Solvent Choice
To be technically viable while meeting economic objectives, the
solvent for deasphalting heavy crude (less than 2 API) needs to be heavy
enough (high enough molecular weight) to just precipitate out the necessary
asphaltenes while keeping the DA0 in solution with the solvent. Also, the
solvent
must be light enough to flash during the transfer of the asphalt extractor
bottoms
(solid asphaltenes plus solvent) without requiring large quantities of energy.
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. .
Similarly, the operating temperature has to be cool enough to encourage DAD
solubility in the solvent and warm enough so there is enough heat to flash the
solvent during transport of the solid asphaltenes. For this process, solid
asphaltene precipitation out of solution is mostly insensitive to solvent
selection.
Table 5 provides a comparison of the solvents to be considered when processing
heavy viscous hydrocarbons (-7 to 0 API to the SDA). C6 and C7 provide a high
yield (89-91%) and with the reduced complexity of the process creates a novel
and economically viable process.
Solvent Solids Separation in Required DAC)
Desired Flash Economic Solvent to
Extractor removal in extractor during Solids
Oil Ratio
Transport
04 Yes No Yes No
05 Yes No Yes No
C6 Yes Yes Yes 2.5-4
C7 Yes Yes Yes 2-3
Table 5 ¨ Solvent selection
Based on the similar effectiveness of C6's and C7's to separate out
' asphaltenes, a blend of these hydrocarbons can be considered to reduce
costs.
A rough fraction of transport diluent can be extracted and considered for use
as
the solvent in the SDA. Testing has confirmed that a mixture of C5-C8 (>60%
C6's and C7's) can be a low cost option when sourcing Solvent for the process
10 operation. This further reduces the operating cost of the process through
sourcing readily available solvents ordinarily characterized as diluent for
the feed
to the process.
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The present invention is not intended to be limited to the
embodiments shown herein, but is to be accorded the full scope consistent with
the claims, wherein reference to an element in the singular, such as by use of
the
article "a" or "an" is not intended to mean "one and only one" unless
specifically
so stated, but rather "one or more", All structural and functional equivalents
to
the elements of the various embodiments described throughout the disclosure
that are known or later come to be known to those of ordinary skill in the art
are
intended to be encompassed by the elements of the claims. Moreover, nothing
disclosed herein is intended to be dedicated to the public regardless of
whether
such disclosure is explicitly recited in the claims.
GLOSSARY OF TERMS USED IN THIS APPLICATION
Applicant submits the following to assist the reader in interpreting
this patent application. Of course, these definitions do not replace common
and
ordinary meanings for these terms as would be understood by a person
nominally skilled in the art of the invention, and are meant as an aid, and to
disambiguate meanings where more than one may exist for similar terms.
Asphaltene asphaltenes are the material in crude oil that is (1)
insoluble in n-pentane (or n-heptane) at a dilution ratio of 40 parts alkane
to 1
part crude oil and (2) re-dissolves in toluene.
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Bitumen - shares the attributes of heavy oil but is yet more dense
and viscous. Natural bitumen is oil having a viscosity greater than 10,000 cP
and
an API typically <10.
Bottoms ¨ Crude Material that does not vaporize in the mentioned
thermal cracker. Primarily consists of gas oil, resins and asphaltenes.
Canadian Bitumen ¨ crude oil with gravity API <10 from Canadian
resources.
Canadian Heavy Crudes - comprises of both conventional heavy oil
and bitumen with API <20.
Deasphalted oil (DAO) ¨ Portion of heavy oil that has majority of
asphaltenes removed with a boiling range of nominally 500+ F.
Gas oil - portion of any crude oil that boilings in the range of 520-
1000 F.
Heavy oil - is an asphaltic, dense (low API gravity <20 API), and
viscous oil (limit of 100 cP) that is chemically characterized by its content
of
asphaltenes (very large molecules incorporating most of the sulfur and perhaps
90 percent of the metals in the oil).
Light ends - Hydrocarbon that consists of 5 carbon chains and less,
typically comprising of pentanes, pentylenes butanes, butylenes, propane,
propylene, ethane, ethylene and methane Includes all material found in crude
oil
and bitumen with Boiling points below 100 F at atmospheric conditions.
MCR means micro carbon residue.
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Resin- Portion of Heavy Oil that is in the 800+ F boiling range and
can contain asphaltenes.
SDA means "solvent deasphalter" or "solvent deasphalting" and
refers typically to a SDA unit, which is a processing apparatus (or step) for
solvent deasphalting (removal of asphalt from a process fluid using solvent).
Syngas ¨ a gaseous mixture primarily comprised of hydrogen,
methane, carbon monoxide, and contaminants generated from the destructive
distillation of hydrocarbons.
Topped crude oil - A portion of the crude stream remaining after the
removal by distillation or other means of an appreciable quantity of the more
volatile components of crude petroleum (eg. Light ends).
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