U.S. patent application number 09/349493 was filed with the patent office on 2001-06-07 for method of and means for upgrading hydrocarbons containing metals and asphaltenes.
Invention is credited to BRONICKI, LUCIEN Y., GOLDSTEIN, RANDALL S., HOOD, RICHARD L., RETTGER, PHILLIP B..
Application Number | 20010002654 09/349493 |
Document ID | / |
Family ID | 25428315 |
Filed Date | 2001-06-07 |
United States Patent
Application |
20010002654 |
Kind Code |
A1 |
HOOD, RICHARD L. ; et
al. |
June 7, 2001 |
METHOD OF AND MEANS FOR UPGRADING HYDROCARBONS CONTAINING METALS
AND ASPHALTENES
Abstract
A hydrocarbon source feed is upgraded using a solvent
deasphalting (SDA) unit employing a solvent having a critical
temperature T.sub.c by initially separating from a first
hydrocarbon input stream fractions with an atmospheric equivalent
boiling temperature less than about T.sub.f.degree.F. for producing
a stream of T.sub.f.sup.- fractions and a residue stream
(T.sub.f.sup.+ stream), where T.sub.f is greater than about
T.sub.c-50.degree. F. In the SDA unit, a second hydrocarbon input
stream which includes the residue stream is deasphalted for
producing a first product stream of substantially solvent-free
asphaltenes, and a second product stream containing substantially
solvent-free deasphalted oil (DAO). The source feed may be included
in either the first or second input streams. The DAO in the second
product stream is thermally cracked for producing an output stream
that includes thermally cracked fractions and by-product
asphaltenes produced by thermally cracking the DAO. Finally, at
least some the said thermally cracked fractions are included in the
first input stream.
Inventors: |
HOOD, RICHARD L.; (EDMOND,
OK) ; RETTGER, PHILLIP B.; (WALNUT CREEK, CA)
; GOLDSTEIN, RANDALL S.; (MORAGA, CA) ; BRONICKI,
LUCIEN Y.; (YAVNE, IL) |
Correspondence
Address: |
NATH AND ASSOCIATES
1030 FIFTEEN STREET
6TH FLOOR
WASHINGTON
DC
20005
US
|
Family ID: |
25428315 |
Appl. No.: |
09/349493 |
Filed: |
July 9, 1999 |
Current U.S.
Class: |
208/309 |
Current CPC
Class: |
C10G 55/04 20130101 |
Class at
Publication: |
208/309 |
International
Class: |
C10G 003/00 |
Claims
1. A method for upgrading a hydrocarbon source feed using a solvent
deasphalting (SDA) unit employing a solvent having a critical
temperature T.sub.c, said method comprising: a) separating from a
first hydrocarbon input stream fractions with an atmospheric
equivalent boiling temperature less than about T.sub.f.degree.F.
for producing a stream of T.sub.f.sup.- fractions and a residue
stream (T.sub.f.sup.+ stream), where T.sub.f is greater than about
T.sub.c-50.degree. F.; b) de-asphalting, in said SDA unit, a second
hydrocarbon input stream which includes said residue stream for
producing a first product stream of substantially solvent-free
asphaltenes, and a second product stream containing substantially
solvent-free deasphalted oil (DAO); c) including said source feed
in said first or second input streams; d) thermally cracking the
DAO in said second product stream for producing an output stream
that includes thermally cracked fractions and by-product
asphaltenes produced by thermally cracking the DAO; and e)
including at least some of said thermally cracked fractions in said
first input stream.
2. A method according to claim 1 wherein at least some of said
by-product asphaltenes are included in said first input stream.
3. A method according to claim 1 wherein at least some of said
output stream is included in said first input stream.
4. A method according to claim 1 wherein said source feed is
included in said first input stream if said source stream contains
fractions with an atmospheric equivalent boiling temperature less
than about T.sub.f.degree.F.
5. A method according to claim 1 wherein said source feed is
included in said second input stream if said source stream contains
no fractions with an atmospheric equivalent boiling temperature
less than about T.sub.f.degree.F.
6. A method according to claim 1 wherein said stream of
T.sub.f.sup.- fractions is separated from said first input stream
by heating said first input stream to about T.sub.f.degree.F. to
form a heated first input stream and then fractionating said heated
first input stream, and cooling said stream of T.sub.f.sup.-
fractions by heating said source feed with said stream of
T.sub.f.sup.- fractions.
7. A method for processing a hydrocarbon feed comprising: a)
heating and then fractionating said hydrocarbon feed to produce a
stream of fractions with an atmospheric equivalent boiling
temperature less than T.sub.f.degree.F. for producing a stream of
T.sub.f.sup.- fractions and a residue stream (T.sub.f.sup.+
stream); b) cooling said T.sub.f.sup.+ stream to form a cooled
stream; c) mixing a solvent with said cooled stream for effecting
separation of the cooled stream into a stream of deasphalted oil
(DAO) and solvent, and a stream of asphaltenes and solvent; and d)
cooling of said T.sub.f.sup.+ stream being effected by exchanging
heat between said stream of DAO and solvent, and said T.sub.f.sup.+
Stream, and between said stream of asphaltenes and solvent and said
T.sub.f.sup.+ stream.
8. A method for processing a hydrocarbon feed containing no
fractions with atmospheric equivalent boiling temperatures less
than about 450.degree. F. comprising: a) mixing a solvent with said
hydrocarbon feed for effecting separation of the feed into a stream
of deasphalted oil (DAO) and solvent, and a stream of asphaltenes
and solvent; b) heating said stream of DAO and solvent with a heat
transfer fluid until supercritical conditions are reached and the
stream separates into two portions, a portion containing solvent
and a small amount of DAO, and a portion containing DAO and reduced
solvent; c) heating said portion containing DAO and reduced solvent
with a heat transfer fluid for forming a DAO product stream
substantially free of solvent but containing fractions with
atmospheric equivalent boiling temperatures greater than
450.degree. F. (atmospheric DAO product stream); d) heating said
atmospheric DAO product stream with a heat transfer fluid to form a
heated DAO product stream; e) fractionating said heated DAO product
stream to separate fractions with atmospheric equivalent boiling
temperatures less than about 1100.degree. F. for producing a stream
of vacuum distillate fractions and a residue stream of vacuum DAO
product; and f) wherein said stream of vacuum distillate fractions
constitutes at least one of said heat transfer fluids.
9. A method for upgrading a hydrocarbon source feed using a solvent
deasphalting (SDA) unit employing a solvent having a critical
temperature T.sub.c, said method comprising: a) separating from a
first hydrocarbon input stream fractions with an atmospheric
equivalent boiling temperature less than about 450.degree. F.
(atmospheric distillates) for producing a 450.sup.- fraction stream
and a 450.sup.+ residue stream; b) de-asphalting a second
hydrocarbon input stream which includes said 450.sup.+ residue
stream, using a solvent for producing a first product stream of
substantially solvent-free asphaltenes, and a second product stream
containing substantially solvent-free deasphalted oil (atmospheric
DAO stream); c) including said source feed in said first or second
input streams; d) heating said atmospheric DAO stream to form a
heated atmospheric DAO stream; e) separating from said heated
atmospheric DAO stream, a stream of fractions having atmospheric
equivalent boiling temperatures less than about 1100.degree. F.
(vacuum distillate fractions), and a residue stream of vacuum DAO;
f) thermally cracking said residue stream of vacuum DAO for
producing an output stream that includes thermally cracked
fractions with an atmospheric equivalent boiling temperature less
than about 1100.degree. F. and by-product asphaltenes produced by
thermally cracking said residue stream of vacuum DAO; and g)
fractionating said output stream to separate therefrom fractions
with atmospheric equivalent boiling temperatures less than about
1100.degree. F. for producing a vacuum residue stream that includes
said by-product asphaltenes.
10. A method according to claim 9 including blending lighter
fractions with said vacuum residue stream to form a blended
fuel.
11. A method according to claim 9 including causing said vacuum
residue stream to be included with one of said input streams.
12. Apparatus including an upgrader for upgrading a hydrocarbon
source feed, said upgrader comprising: a) a fractionator for
receiving a first hydrocarbon input stream and separating the same
into fractions with an atmospheric equivalent boiling temperature
less than about T.sub.f.degree.F. (T.sub.f.sup.- fractions) thereby
producing a product stream that consists of T.sub.f.sup.-
fractions, and a residue stream (T.sub.f.sup.+ stream); b) a
solvent deasphalting (SDA) unit utilizing a solvent having a
critical temperature T.sub.c for receiving a second hydrocarbon
input stream which includes said residue stream for producing a
first product stream of substantially solvent-free asphaltenes, and
a second product stream containing substantially solvent-free
deasphalted oil (DAO), and wherein T.sub.f is greater than about
T.sub.c-50.degree. F.; c) means for including said source feed in
said first or second input streams; d) a thermal cracker for
thermally cracking the DAO in said second product stream for
producing an output stream that includes thermally cracked
fractions and by-product asphaltenes produced by thermally cracking
the DAO; and e) means for feeding-back at least some of said
thermally cracked fractions to said first input stream.
13. Apparatus according to claim 12 wherein said means for
including said source feed is constructed and arranged to include
said source feed in said second input stream when said source
stream contains fractions with an atmospheric equivalent boiling
temperature less than about T.sub.f.degree.F.
14. Apparatus according to claim 12 wherein said means for
including said source feed is constructed and arranged to include
said source feed in said first input stream when said said source
stream contains no fractions with an atmospheric equivalent boiling
temperature less than about T.sub.f.degree.F.
15. Apparatus according to claim 12 including: a) a prime mover
operating on a non-asphaltene product stream produced by said
upgrader for generating power and producing exhaust gases; b) a
combustor for combusting asphaltenes from said product stream of
asphaltenes produced by said upgrader, and producing combustion
gases; d) a waste heat boiler responsive to said combustion gases
for generating steam; and e) a steam turbine responsive to said
steam for producing power.
16. Apparatus according to claim 15 wherein said waste heat boiler
is responsive to said exhaust gases as well as said combustion
gases for generating steam.
17. Apparatus according to claim 15 wherein said combustor is a
fluidized bed combustor.
18. Apparatus according to claim 15 wherein said prime mover is a
gas turbine unit having a compressor for compressing ambient air
and producing a compressed air stream, a burner to which said
compressed air stream is supplied and to which is supplied said
non-asphaltene product from said upgrader for heating the air and
producing a heated stream of air, and a gas turbine responsive to
said heated stream of air for generating power and producing
exhaust gases, and means for supplying said exhaust gases to said
combustor.
19. Apparatus according to claim 18 including a heat exchanger
interposed between said burner and said compressor and operatively
associated with said combustor for transferring heat from said
combustor to said compressed air stream.
20. Apparatus according to claim 12 including: a) a gas turbine
unit having a compressor for compressing ambient air and producing
a compressed air stream, a burner to which said compressed air
stream is supplied and to which is supplied said non-asphaltene
product from said upgrader for heating the air and producing a
heated stream of air, and a gas turbine responsive to said heated
stream of air for generating power and producing exhaust gases; b)
a waste heat boiler responsive to said exhaust gases for generating
steam; c) an air turbine unit having a compressor for compressing
ambient air and producing a compressed air stream, a heat exchanger
for heating the air and producing a heated stream of air, and an
air turbine responsive to said heated stream of air for generating
power and producing a heat-depleted stream of air; d) a combustor
for combusting asphaltenes from said product stream of asphaltenes
produced by said upgrader, and producing combustion gases; e) said
heat exchanger being responsive to said combustor for supplying
heat to said compressed air stream; f) a waste heat boiler
responsive to said combustion gases for generating steam; and g) a
steam turbine responsive to steam from a waste heat boiler for
producing power.
21. In combination: a) a power generator system including a prime
mover that generates power and produces exhaust gases; b) a solvent
deasphalting unit that receives a hydrocarbon feed for producing a
substantially solvent-free asphaltene product, and a substantially
solvent-free non-asphaltene product in response to input heat; c)
means for using said waste heat to supply said input heat.
22. Apparatus according to claim 12 including a prime mover
operating on a non-asphaltene product stream produced by said
upgrader for generating power and exhaust gases.
23. Apparatus according to claim 22 including means responsive to
said exhaust gases for transferring heat to said upgrader.
Description
TECHNICAL FIELD
[0001] This invention relates to upgrading of hydrocarbons
containing metals and asphaltenes and more particularly is
concerned with a method of and means for upgrading such
hydrocarbons prior to their use as fuel in power generation systems
or as refinery feedstocks.
BACKGROUND TO THE INVENTION
[0002] Many liquid hydrocarbons are comprised of various fractions
which vaporize under atmospheric or subatmospheric pressure, at
different temperatures. In typical practice, such hydrocarbons are
fractionated by heating and vaporizing one or more of such
fractions to separate the lighter, lower boiling range fractions
from the heavier, higher boiling range material. Since the process
of fractionation separates the lighter, lower boiling range
fractions as vapors, certain constituents of the hydrocarbons which
do not vaporize remain in the heavier, higher boiling range portion
of the hydrocarbon. Examples of constituents with this
characteristic include metals, asphaltenes (pentane-insolubles),
and coke pre-cursors, such as those measured by ASTM test
procedures D-189 and designated as Conradson Carbon Residue
(CCR).
[0003] These constituents are a problem for a variety of potential
users of the heavier, higher boiling range portion of the
hydrocarbon. Examples of users for whom such constituents present a
problem include power generation devices, such as combustion
turbines and internal combustion engines, and refinery process
units such as catalyst-based cracking and hydrotreating units and
thermal cracking units.
[0004] An example of a user that is effected by the constituents
present in the heavier, higher boiling range portion of oil is the
combustion turbine, which is one of the lowest cost, highest
efficiency power generation systems available today. Combustion
turbines can also be configured in a combined cycle configuration
to further increase the efficiency of a power generation cycle.
Combustion turbines can be damaged when using liquid fuels that
contain significant amounts of metals. To avoid such damage, users
of combustion turbines can: (1) use fuel with low levels of metals,
(2) use fuel pre-processing systems to reduce the level of metals
in the fuel burned, (3) add chemicals to the fuel to reduce the
negative impacts of the metals in the fuel, or (4) operate the
combustion turbine at a lower, and less efficient firing
temperature to reduce the impact of the metals. Each of these
options results in an increased cost of power generation, whether
from additional capital, additional operating costs, or lower power
generation efficiency.
[0005] One of the lowest cost liquid fuels available for use in
combustion turbines is heavy fuel oil. Such oil is produced by
mixing the heavier, higher boiling range portion of the hydrocarbon
with sufficient light petroleum diluent, e.g., diesel fuel, to
achieve the desired product properties. While the resultant heavy
fuel oil usually has a lower cost than other liquid fuel products,
the level of metals in the oil is usually higher, causing higher
operating and maintenance costs and lower power generation
efficiencies in combustion turbines. Moreover, such heavy fuel oil
contains some amount of light petroleum product as diluent and the
diluent alone has a higher value than that of the heavy fuel
oil.
[0006] Conventionally, the low quality of the heavy fuel oil can be
improved prior to use by fuel treatment systems such as
centrifuging or settling to remove sediment, water washing to
remove water soluble corrosive salts, and the addition of
inhibitors to control the effect of non-removable corrosive
elements.
[0007] The cost of heavy fuel oil can be reduced by purchasing
lower quality product, which then requires the use of a greater
amount of fuel treatment, which results in lower combustion turbine
efficiency and increases downtime.
[0008] 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.
[0009] In U.S. Pat. No. 4,528,100, a process for the treatment of
residual oil is disclosed, the process comprising the steps of
treating the residual oil so as to produce a first extract and a
first raffinate using supercritical solvent extraction, and then
treating the first raffinate so as to produce a second extract and
a second raffinate again by supercritical solvent extraction using
a second supercritical solvent and then combining the first extract
and the raffinate to a product fuel. In accordance with a
particular embodiment of the invention disclosed in the U.S. '100
patent, the supercritical solvents are particularly selected to
concentrate vanadium in the second extract. Thus, even though the
amount of vanadium present in the product fuel is low and
consequently beneficial for reducing gas turbine maintenance
problems as stated in this U.S. '100 patent, some amount of
vanadium does still remain therein.
[0010] Another example of a user of the heavier, higher boiling
range portion of a hydrocarbon is a refinery with a fluid catalytic
cracking unit (an FCC unit). FCC units typically are operated with
a feedstock quality constraint of very low metals asphaltenes, and
CCR (i.e., less than 10 wppm metals, less than 0.2 wt %
asphaltenes, and less than 2 wt % CCR). Utilization of feedstocks
with greater levels of asphaltenes or CCR results in increased coke
production and a corresponding reduction in unit capacity. In
addition, use of feedstocks with high levels of metals and
asphaltenes results in more rapid deactivation of the catalyst, and
thus increased catalyst consumption rates and increased catalyst
replacement costs.
[0011] In U.S. Pat. No. 5,192,421, a process for the treatment of
whole crude oil is disclosed, the process comprising the steps of
deasphalting the crude by first mixing the crude with an aromatic
solvent, and then mixing the crude-aromatic solvent mixture with an
aliphatic solvent. The U.S. '421 patent (at page 9, lines 43-45)
identifies that certain modifications must be made to prior art
solvent deasphalting technologies, such as that described in U.S.
Pat. Nos. 2,940,920, 3,005,769, and 3,053,751 in order to
accommodate the process described in the U.S. '421 patent, in
particular since the prior art solvent deasphalting technologies
have no means to remove that portion of the charge oil that will
vaporize concurrently with the solvent and thus contaminate the
solvent used in the process. In addition to being burdened by the
complexity and cost resulting from the use of two solvents, the
U.S. '421 process results in a deasphalted product that still
contains a non-distilled portion with levels of CCR and metals that
exceed the desired levels of such contaminants.
[0012] 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. '028 patent is
burdened by the complexity and cost of a two-stage solvent
deasphalting system to separate the resin fraction from the
deasphalted oil, in addition, like the U.S. '421 patent, the '028
process results in an upgraded product that still contains a
non-distilled fraction--the DAO--that is contaminated with CCR and
metals.
[0013] 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
with the visbroken distillates; and recycling and combining resins
from the deasphalting step with the feed initially delivered to the
visbreaker. The U.S. '023 patent is burdened by the complexity and
cost of a two-stage solvent deasphalting system to separate the
resin fraction from the deasphalted oil. In addition, the '023
process results in an upgraded product that still contains a
non-distilled fraction--the DAO--that is contaminated with CCR and
metals.
[0014] 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 the distillable catalytic cracking
fractions (atmospheric equivalent boiling temperature of less than
about 1100.degree. F.) to produce products comprising
transportation fuels, light gases, and slurry oil. The U.S. Pat.
No. '697 is burdened by the complexity, cost, and technical
viability of vacuum distilling a topped heavy crude to about
850.degree. F. and catalytic cracking the deasphalted oil to
produce transportation fuels. This level of upgrading is too
complex and required too large of a scale to be useful for oil
field applications, and U.S. Pat. No. '697 selectively eliminates
the majority of the material that could be used as fuel for a
combustion turbine or internal combustion engine without further
upgrading. It is therefore an object of the present invention to
provide a new and improved method of and means for upgrading
hydrocarbons containing metals and asphaltenes wherein the
disadvantages as outlined are reduced or substantially
overcome.
SUMMARY OF THE INVENTION
[0015] According to the present invention, a method of and means
for upgrading a hydrocarbon containing metals and asphaltenes is
provided, the method comprising the steps of: supplying the
hydrocarbon containing metals and asphaltenes to a vaporizer
present in a deasphalting unit and operating at, above, or below
atmospheric pressure for heating and vaporizing the hydrocarbon at
a temperature sufficient to vaporize at least that fraction of the
hydrocarbon which has an atmospheric boiling temperature less than
about 50.degree. F. below the critical temperature of the solvent
used in the deasphalting unit; removing and subsequently condensing
the hydrocarbon fraction so vaporized from the balance of the
hydrocarbon to be upgraded, prior to the addition of the solvent to
the hydrocarbon; and processing the hydrocarbon remaining after the
initial vaporization step in a solvent deasphalting unit such as
that disclosed in copending U.S. patent application Ser. No.
08/862,437 filed on May 23, 1997, the disclosure of which is hereby
included by reference, to produce atmospheric distillate,
deasphalted oil (DAO) and asphaltenes.
[0016] Usually, the step of supplying the hydrocarbon to a
vaporizer present in a deasphalting unit and operating at, above,
or below atmospheric pressure for heating and vaporizing the
hydrocarbon is carried out by supplying the hydrocarbon to a heater
for heating the hydrocarbon and thereafter supplying the heated
hydrocarbon to a fractionation column. If a prior art solvent
deasphalting unit is used, all of the material boiling below an
atmospheric equivalent temperature of about 450.degree. F. will
have to be removed in the vaporization step in order to prevent
contamination of the solvent, and the SDA unit will produce only
DAO and asphaltenes. In a preferred embodiment of the present
invention, the DAO (or atmospheric DAO) is firstly fractionated in
a fractionation column which may be a distillation column or flash
vessel which may be included in the SDA unit to produce vacuum
distillate (i.e., fractions with atmospheric equivalent boiling
temperatures less than about 1100.degree. F.) and non-distilled DAO
residue (vacuum DAO), and the non-distilled DAO residue is heated
for sufficient time and at suitable temperature conditions to
thermally crack the non-distilled DAO residue into thermally
cracked lighter, lower boiling range fractions (comprising
thermally cracked fractions with atmospheric equivalent boiling
temperatures less than about 1100.degree. F.), and a thermal
cracker residue fraction (thermal cracker residue, or TCR,
comprising by-product asphaltenes, unconverted vacuum DAO, thermal
cracker gases, etc. ); and fractionating the TCR in a further
fractionation column operating at sub-atmospheric pressure to
separate thermally cracked vacuum distillate fractions (i.e.,
fractions with atmospheric equivalent boiling temperatures in the
range 650-1050.degree. F.) from the non-distilled TCR. Note that
throughout the text the term fractionating, column is used and is
taken to mean a distillation column or flash vessel.
[0017] The distilled, thermally cracked and low boiling range
fractions and the thermally cracked vacuum distillate are
substantially asphaltene-free and metal-free and can be used, alone
or re-combined with one or more of the distillate fractions
obtained from the original feedstock, without further treatment, as
a replacement for premium distillate fuels or refinery
feedstocks.
[0018] According to the present invention, the TCR fraction can be
substantially recycled and combined with the feed to the solvent
deasphalting unit.
[0019] In the course of cracking the non-distilled DAO residue,
asphaltenes are produced as a by-product of the thermal cracking
process. Under severe thermal cracking conditions, such as would be
employed to maximize the generation of lighter products, sufficient
asphaltenes can be created in the thermal cracking step so as to
cause precipitation of asphaltenes and fouling of the thermal
cracker heater exchanger, or precipitation of the asphaltenes from
the thermal cracker in subsequent storage or transport. The
precipitation of asphaltenes thus produces a limit on the severity
and yield of lighter, lower boiling range fractions and vacuum
distillate fractions from the thermal cracking process.
[0020] According to the present invention, the asphaltenes present
in the hydrocarbons to be upgraded are removed in the deasphalting
step prior to the thermal cracking step. In addition, by recycling
the TCR, which contains asphaltenes created as a by-product of the
thermal cracking to the solvent deasphalting step, the thermal
cracker-produced asphaltenes are removed from the TCR and the
deasphalted TCR can be returned to the thermal cracker for further
cracking. Thus, according to the present invention, the removal of
asphaltenes from the initial and the recycled feedstocks to the
thermal cracker allow for a much improved level of conversion of
non-distilled hydrocarbon into distillates than is possible with
the prior art.
[0021] Furthermore, in accordance with the present invention, the
recycled TCR stream can be used to provide at least some of the
heat required to achieve the desired temperature for the initial
vaporization step of the process.
[0022] According to the present invention, the asphaltenes produced
from the invention can be used as fuel by another fuel user. For
example, these asphaltenes can be used as fuel in a fluidized bed
combustor or high viscosity fuel oil boiler, or emulsified and used
in as an alternative to heavy fuel oil in conventional systems.
Alternatively, the asphaltenes can be used As fuel in a gasifier,
or they can be cracked to produce lighter liquid fuels. If so
cracked, the distillate fuel produced from the asphaltenes can be
combined with the distillate products that result from the cracking
of the DAO or from the fractionation of the original feedstock to
the process.
[0023] In accordance with another embodiment of the present
invention, the hydrocarbon to be upgraded can sometimes comprise
non-distilled residue which contains metals, asphaltenes, and CCR,
combined with a lower-boiling range hydrocarbon diluent to achieve
a desired viscosity and density of the combined oil. Such diluent,
if separated from the non-distilled residue, is a valuable fuel
which requires no further processing. In the case of a
non-distilled-heavy oil and diluent mixture, the invention would
comprise of the steps of supplying the heavy oil or hydrocarbon
mixture to a diluent vaporizer present in the deasphalting unit for
heating and vaporizing the hydrocarbon at a temperature sufficient
to vaporize or boil off the diluent and subsequently condensing the
diluent; and processing the remaining distillation residue in the
deasphalting unit as previously described. Usually the step of
supplying the heavy oil or hydrocarbon mixture to a vaporizer
present in a deasphalting unit for heating and vaporizing the
diluent is carried out by supplying the heavy oil or hydrocarbon
mixture to a heater for heating the heavy oil or hydrocarbon
mixture and thereafter supplying the heated heavy oil or
hydrocarbon mixture to a fractionation column.
[0024] In accordance with another embodiment of the invention, if
the hydrocarbons to be upgraded contains a fraction that is
distillable at an equivalent atmospheric boiling temperature less
than about 50.degree. F. below the critical temperature of the
solvent used in the solvent deasphalting step, the invention can be
used to simultaneously fractionate and deasphalt in one device to
produce as separate products distillates, non-distillable
deasphalted oil, and asphaltenes.
[0025] In a further embodiment of the invention, diluent, either
from a deasphalting unit or from another source, can be added to
the asphaltenes exiting the deasphalting unit to produce heavy fuel
oil.
[0026] In another embodiment of the invention, if the invention is
used at the site of a power generation system, such as a combustion
turbine, to produce fuel for the power generation, system, then
waste heat from the power generation unit can be used to provide at
least some of the thermal energy required by the deasphalting or
thermal cracking steps.
[0027] Furthermore, the present invention also comprises means or
apparatus for carrying out the method or methods of the present
invention. In an embodiment of means for upgrading hydrocarbons
containing metals and asphaltenes in accordance with the present
invention, apparatus comprises a heat exchanger and vaporizer
contained in a deasphalting unit for heating the hydrocarbons to a
temperature sufficient to vaporize at least that fraction of
hydrocarbon which has an atmospheric boiling temperature less than
about 50.degree. F. below the critical temperature of the solvent
used in the solvent deasphalting process and boiling off and
subsequently condensing the fraction so vaporized; and means for
supplying the remaining hydrocarbon to a deasphalting unit such as
that disclosed in copending U.S. patent application Ser. No. ______
filed on May 23, 1997, for producing deasphalted oil (DAO) and
asphaltenes. If a prior art solvent deasphalting unit is used, all
of the material boiling below an atmospheric equivalent temperature
of about 450-650.degree. F. will have to be removed in the
vaporization step in order to prevent contamination of the solvent,
and the SDA unit will produce only DAO and asphaltenes. In a
preferred embodiment of the present invention, means for
fractionating the resulting deasphalted oil under subatmospheric
conditions are provided which may be included in the SDA unit, as
well as means for thermally cracking and distilling the
non-distillate residue of the DAO.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Embodiments of the invention are described by way of
example, and with reference to the accompanying drawings
wherein:
[0029] FIG. 1A is a block diagram of one embodiment of a heavy oil
upgrader according to the present invention;
[0030] FIG. 1B is a block diagram of a modified version of the
embodiment of FIG. 1A;
[0031] FIG. 2A is a block diagram showing details of the front-end
and solvent deasphalting unit of a heavy oil upgrader according to
the present invention;
[0032] FIG. 2B is a block diagram showing details of a further
portion of the upgrader shown in FIG. 2A;
[0033] FIG. 3 is a block diagram showing details of a thermal
cracker and other components of the upgrader shown in FIGS. 2A and
2B;
[0034] FIG. 4A is a block diagram of one embodiment of a power
plant incorporated into an upgrader according to the present
invention;
[0035] FIG. 4B is a block diagram of a modified version of the
embodiment of FIG. 4A;
[0036] FIG. 5 is a block diagram of a further embodiment of a power
plant incorporated into an upgrader according to the present
invention;
[0037] FIG. 6 is a block diagram of a still further embodiment of
the present invention; and
[0038] FIG. 7 is a schematic showing of the use of waste heat in a
conventional power generation system for supplying heat to an
upgrader according to the present invention.
DETAILED DESCRIPTION
[0039] Turning now to the drawings wherein like reference
characters in the various figures designate like components,
reference numeral 10A in FIG. 1A, and reference numeral 10B in FIG.
1B, designate embodiments of a heavy oil upgrader according to the
present invention. Upgrader 10A functions to upgrade a source feed
of crude oil, which is mainly heavy hydrocarbons but typically
contains light fractions, heavy metals, asphaltenes, etc., to a
plurality of valuable non-asphaltene product streams including
atmospheric and vacuum distillates, etc., and to a less valuable
asphaltene product stream that contains most of the metals, coke
pre-cusors, etc. present in the source feed. Upgrader 10B in FIG.
1B functions to upgrade a source feed, such as atmospheric or
vacuum residual, which lacks light fractions with atmospheric
equivalent boiling temperatures below about 450.degree. F.
[0040] An upgrader according to the present invention, utilizes a
solvent deasphalting (SDA) unit 11 that employs a solvent having a
critical temperature T.sub.c, and includes fractionator 12
constructed as a distillation column, and arranged to separate from
first hydrocarbon input stream 13, fractions with an atmospheric
equivalent boiling temperature less than about T.sub.f.degree.F.
for producing stream 14 of T.sub.f.sup.- fractions (e.g., naphtha,
atmospheric distillate, vacuum distillate, etc.) and residue stream
15 (T.sub.f.sup.+ stream), where T.sub.f is greater than about
T.sub.c-50.degree. F. Typically, T.sub.f will be less than about
1100.degree. F.
[0041] SDA unit 11, which may be either of conventional design, or
constructed in accordance with the details shown in FIGS. 2A, 2B,
and 3, deasphalts second hydrocarbon input stream 16, which
includes residue stream 15, for producing first product stream 17
of substantially solvent-free asphaltenes, and second product
stream 18 containing substantially solvent-free deasphalted oil
(DAO).
[0042] Source feed 19A is included in first input stream 13 (FIG.
1A) when feed 19A contains fractions with an atmospheric equivalent
boiling temperature less than about T.sub.f.degree.F. However, if
source feed 19B contains no such fractions, then source feed 19B
bypasses fractionator 12 and is included in the second input stream
(FIG. 1B). Thus, the source feed is included in either the first or
second input streams according to the nature of the source
feed.
[0043] Second product stream 18 containing DAO is heated in heater
20 and then cracked in thermal cracker 21. The cracking operation
that takes place in cracker 21 produces output stream 22 that
includes thermally cracked fractions and by-product asphaltenes
produced by thermally cracking the DAO. Stream 22 also contains
unconverted DAO the level of which is dependent on the efficiency
of conversion of thermal cracker 21.
[0044] At least some of the thermally cracked fractions in stream
22 are fed back through heat exchanger 23 to first input stream 13
supplying fractionator 12. The entire output stream may be fed back
to allow fractionator 12 to separate all of the lighter fractions
produced by the thermal cracking process, and to allow the SDA unit
to separate by-product asphaltenes produced by the thermal cracking
process.
[0045] Stream 14 of T.sub.f.sup.- fractions produced by
fractionator 12 is cooled prior to storage or use by passing this
stream through heat exchanger 24 wherein heat contained in stream
14 is transferred to the source feed which is preheated in
preparation either for removing light fractions (FIG. 1A), or for
processing by SDA unit 11 (FIG. 1B). Note that in FIG. 1A, the
first input stream consists of source feed 19A and output 22 of the
thermal cracker, and the second input stream consists of residue
stream 15. In FIG. 1B, the first input stream consists of output 22
of the thermal cracker, and the second input stream consists of
source feed 19B and residue stream 15.
[0046] The upgraders shown in FIGS. 1A and 1B have a single input,
namely, a hydrocarbon source feed, and two main products as
outputs: a range of non-asphaltene product streams of valuable
light fractions, and a less valuable asphaltene product stream.
Thus, the upgraders of the present invention represent a
particularly simple technological solution for upgrading heavy
hydrocarbon feedstock to provide fuel for power generation, or
feedstock for a refinery.
[0047] Preferably, the fractionator shown in FIG. 1A and FIG. 1B is
integrated into an SDA unit to establish a new and improved
upgrader designated by reference numeral 30 in FIGS. 2A, 2B and 3.
Referring first to FIG. 2A, upgrader 30 receives hydrocarbon feed
31, such as crude oil usually containing light fractions, which if
not removed upstream of SDA unit 18', adversely affect the
operation of the SDA unit due to the trapping of the light
fractions in the solvent. The feed is heated in passing through
serially disposed heat exchangers E1 and E2 (which correspond to
heat exchanger 24 in FIG. 1A), and H1 to about 450.degree. F. and
applied to fractionator V1 which produces a stream of atmospheric
distillate (i.e., fractions such as naphtha with atmospheric
equivalent boiling temperatures less that about 450.degree. F.)
which passes out the top of the fractionator. The stream of
atmospheric distillate flows through conduit 33 and is cooled by
transferring heat to feed 31 in heat exchanger E2 forming a product
stream in conduit 33'. Residue 32 passes out the bottom of
fractionator V1. Because this residue is what remains in the
fractionator after atmospheric distillate is removed, thus residue
is referred to as atmospheric residue for reference purposes.
[0048] In order to utilize a solvent deasphalting process to
separate asphaltenes in residue 32, the temperature of the residue
must be reduced from that of the fractionator V1 to about T.sub.c
where T.sub.c is the critical temperature of he solvent prior to
mixing the residue with a solvent. To this end, the residue is
pumped through conduit 34 by pump P1 at the outlet 34' of
fractionator V1, to inlet 34" of mixer M1 after passing through
serially disposed heat exchangers E3, E4 and E5. If feed 31 is
vacuum resid, heat exchangers H1, E3, E4, and E5 would be
by-passed, and the feed exiting heat exchanger E2 would be applied
directly to input 34" of mixer M1 as indicated by chain line
40.
[0049] Mixer M1 mixes the cooled residue from fractionator V1 with
a solvent (e.g., liquid pentane), and the mixture is applied to
asphaltene separator V2 wherein gravity separates the mixture into
lighter deasphalted oil (DAO) and heavier asphaltenes. Through
conduit 35 at the top of the separator flows a mixture stream of
DAO and solvent, and through conduit 36 at the bottom flows a
mixture stream of asphaltenes and solvent in which a small amount
of DAO is dissolved.
[0050] A product stream of substantially solvent-free DAO (termed
atmospheric DAO product stream because atmospheric distillate has
been removed upstream of SDA unit 18') is produced by SDA 18' by
sequentially applying the mixture of DAO and solvent in conduit 35,
first to supercritical solvent recovery section 37, and then to
evaporative solvent recovery section 38. A product stream of
substantially solvent-free asphaltene is also produced by SDA 18 by
applying the asphaltene and solvent mixture, directly to
evaporative solvent recovery section 38.
[0051] Section 37 includes serially disposed heat exchangers E6-9
associated with conduit 35 so that the stream of DAO and solvent
produced by separator V2 is heated to above the critical
temperature of the solvent before reaching DAO separator V3 of
section 37. In this separator, phase separation of the fluid takes
place producing a stream of solvent that flows out the top of
separator V3 into conduit 39, and a mixture of DAO and reduced
solvent that flows out the bottom of the separator into conduit
40.
[0052] The temperature of the stream of solvent leaving separator
V3 is above the critical temperature of the solvent and must be
cooled before it can be recycled to mixer M1. Preferably, the
stream of hot solvent is cooled by passing it through heat
exchanger E6 and cooler E10 in preparation for recovering and then
recycling the solvent to mixer M1. Thus, some of the heat added to
the stream of DAO and solvent in conduit 35 to raise the
temperature of the stream to above the critical temperature of the
solvent is recovered in heat exchanger E6 by cooling the hot
solvent from separator V3. Further cooling of the solvent to the
desired temperature for use in mixer M1 is effected by condenser
E10 whose operation is controlled to achieve the desired final
temperature at the outlet of pump P2 which supplies solvent to
mixer M1.
[0053] The temperature of the stream of DAO and reduced solvent
leaving separator V3 through conduit 40 at the bottom of the
separator is also above the critical temperature and pressure of
the solvent. In preparation for flashing this stream in flash drum
V5 in evaporative section 38, which evaporates the reduced solvent
and produces a substantially solvent-free product steam of
atmospheric DAO, the stream of DAO and reduced solvent is further
heated in heat exchanger E3 by transferring heat from the residue
flowing from fractionator V1. Thus, some of the heat added to the
stream in conduit 31 by heater H1 is recovered by heat exchanger
E3.
[0054] In a similar manner, the stream of asphaltene and solvent
mixture in conduit 36 produced by separator V2, which is cooler
than the DAO and reduced solvent stream in conduit 40 produced by
separator V3, is heated in preparation for flashing this stream in
flash drum V4 of evaporation section 38. First, the stream in
conduit 36 passes through heat exchanger E4 downstream of heat
exchanger E3 extracting heat from residue 32 produced by
fractionator V1. The thus preheated stream is further heated in
heat exchanger E11 supplied with hot fluid (preferably hot DAO
product from hot oil supply HOS, FIG. 2B).
[0055] In parallel operations in section 38, the stream of DAO and
reduced solvent leaving heat exchanger E3 is flashed in drum V5,
and the stream of asphaltene and solvent leaving heat exchanger E11
is flashed in drum V4 producing vaporized solvent that is applied
to heat exchanger E7 wherein the DAO and solvent stream in conduit
35 is heated. The residues produced by the flash drums are
respectively applied to strippers V6 and V7 wherein, with the aid
of injected steam and reduced pressure, a substantially
solvent-free product stream of atmospheric DAO is produced at the
bottom of stripper V7, and a substantially solvent-free product
stream of asphaltene is produced at the bottom of stripper V6.
[0056] Before describing the further processing of these two
product steams, the disposition of the vaporized solvent produced
by flash drums V4 and V5, and of the mixture of vaporized solvent
and steam produced by strippers V6 and V7 is described. After the
vaporized solvent produced by drums V4 and V5 is cooled somewhat in
heat exchanger E7, the solvent may still be too hot for proper
expansion in an organic turbine. As a consequence, the solvent is
further cooled in heat exchanger E12 (which preheats solvent pumped
by pump P3,P4 from solvent storage tank V10); and the cooler
vaporized solvent is applied to separator V8 for the purpose of
separating any atmospheric distillate trapped in the solvent.
[0057] Vaporized solvent exits from the top of separator V8 and is
applied to the inlet stage of organic vapor turbine T wherein
expansion occurs driving generator G and producing power. Heat
depleted solvent at lower pressure is exhausted from this turbine,
cooled in heat exchanger E13 (which preheats solvent pumped by pump
P3,P4 from solvent storage tank V10) to remove some of the
superheat from the heat-depleted turbine exhaust, and then
condensed in air-cooled condenser E14 producing liquid solvent that
is stored in tank V10.
[0058] The fluid that exits from the bottom of separator V8
comprises atmospheric distillate and a residual amount of solvent.
To this fluid is added the solvent and steam from the overhead of
strippers V6 and V7; and the combined fluid, a mixture of
atmospheric distillate, solvent, and steam flows though heat
exchanger 15 to separator V9. Cooling of the fluids in heat
exchanger E15 causes the steam and atmospheric distillate to
condense in separator V9. The lower layer of liquid in the
separator is water which is drained from the bottom, and the upper
layer is a liquid comprising atmospheric distillate and perhaps
some naphtha and condensed solvent, which flows to point W upstream
of separator V14. Most of the solvent in separator V9 remains
vaporized and is delivered to solvent condenser E14.
[0059] As indicated above, pumps P3,P4 also deliver make-up solvent
to mixer M1 via pump P2. Condenser E10 is operated at a level that
will establish the appropriate temperature for the solvent applied
by pump P2 to mixer M1 taking into account the temperature of the
solvent in tank V10, and the temperature of the solvent exiting
heat exchanger E6. In addition to supplying make-up solvent to
mixer M1, pumps P3, P4 also supply solvent from tank V10 to an
intermediate stage of turbine T along three parallel paths. In one
path, the solvent is heated by passing through heat exchangers E13
and E12. In a second path, solvent is heated by passing through
heat exchanger E13 and heat exchanger E19 whose function is to cool
atmospheric distillate produced downstream of the SDA unit by a
thermal cracking operation described below. In a third path, the
solvent is heated by passing through heat exchangers E13 and E15.
Thus, the turbine will generate additional power using heat
extracted from the solvent in the turbine exhaust prior to
condensation, from the solvent produced by flash drums V4 and V5,
strippers V6 and V7, and from atmospheric distillate produced by
the SDA unit and the thermal cracker that is downstream of the SDA
unit.
[0060] The mixture of liquids at point W arriving from separator V9
is joined by the distillate that passes through heat exchanger E2,
and distillate (produced by the downstream thermal cracking
operation) that passes through heat exchanger E1. This combined
stream is applied to separator V14 wherein, at a reduced pressure,
the lighter fractions vaporize and pass out the top of the
separator. The vapor passing out the top of separator V14 is
vaporized solvent, steam, and naphtha. This vapor is cooled in
condenser E18 and supplied to separator V15 in which the water and
naphtha separate from the solvent which remains a vapor and is
returned by pump P12 to solvent condenser E14. The naphtha and
steam are separated from each other in separator V16, the water
being drawn from the bottom of this separator. The naphtha is
pumped at P10 to point Z where it is combined with liquid
atmospheric distillate from the bottom of separator 14, and with
vacuum distillate produced by the thermal cracker downstream of SDA
unit 18' to produce a finished product stream that is supplied to
tankage or pipeline.
[0061] As described above, the apparatus shown in FIG. 2A receives
a hydrocarbon feed at 31, and produces the following: a product
stream of substantially solvent-free atmospheric DAO at the output
of stripper V7, a product stream of substantially solvent-free
asphaltene at the output of stripper V6; and, at point Z, a product
stream that is a blend of virgin atmospheric and vacuum distillates
and naphtha (i.e., fractions present in the original feed), as well
as atmospheric and vacuum distillates and naphtha produced by the
thermal cracking process applied to the DAO product stream.
[0062] Pump P6 at the outlet of stripper V7 delivers the
atmospheric DAO product stream to holding tank V12 as shown in FIG.
2B to which reference is now made. Tank V12 is at ambient
temperature, and any solvent or light non-condensable gases in the
DAO are removed from the overhead of this tank and burned with
additional fuel to heat DAO from tank V12 delivered by pump P7 to
heater H2. Some of the hot DAO produced by heater H2 is supplied to
heat exchanger E9 in supercritical section 37 of the SDA unit (FIG.
2A) and to heater H1 upstream of fractionator V1 (FIG. 2A). Because
the hot DAO used as a heat exchange fluid is constantly renewed by
the SDA unit, the quality of the heat exchange fluid supplied to
the SDA unit for heating does not deteriorate over time. This
technique is disclosed in copending application Ser. No. 08/710,545
filed Sep. 19, 1996, the disclosure of which is hereby incorporated
by reference.
[0063] The bulk of the hot DAO, however, is supplied to vacuum
fractionator V13 which produces at its overhead, a stream of
fractions with atmospheric equivalent boiling temperatures less
than about 1100.degree. F. (vacuum distillate), and which at its
bottom, produces a residue stream that is termed vacuum DAO (i.e.,
DAO that remains after vacuum distillate is removed). The vacuum
distillate produced by fractionator V13 is cooled in heat exchanger
E8 (FIG. 2A) which helps raise the DAO and solvent mixture from the
asphaltene separator to the supercritical temperature of the
solvent, and then further cooled in heat exchanger E1 (FIG. 2A)
which helps raise the temperature of feed 31 upstream of
fractionator V1.
[0064] The product stream of vacuum DAO is supplied by pump P13 to
heat exchanger E22 (FIG. 3) wherein the stream is preheated, and
then to heater H3 wherein the temperature of the stream is raised
to about 900.degree. F. From this heater, the hot DAO flows to
holding tank V17 of a size that provides sufficient residence time
for thermal cracking of the DAO to take place. The thermally
cracked stream produced by thermal cracker V17 comprises fractions
with atmospheric equivalent boiling temperatures ranging through
about 1100.degree. F., by-product asphaltenes produced by the
thermal cracking process, unconverted vacuum DAO, thermal cracker
gas, etc. all at about 900.degree. F. This hot thermally cracked
stream is cooled by passing through heat exchanger E22 which serves
to heat the stream of vacuum DAO from fractionator V13 (FIG. 2B)
being supplied to the thermal cracker.
[0065] After passing through pressure reducer valve 50, some or all
of the somewhat cooled thermally cracked stream may be supplied to
the input to fractionator V1 as indicated by broken line 41 in FIG.
2A. In such case, the lighter fractions in the thermally cracked
stream would be recovered from the overhead of fractionator V1, and
the remaining portion of the thermal cracked stream, namely
by-product asphaltenes, heavier fractions, and the unconverted DAO
being part of the residue that passes out the bottom of
fractionator V1. Preferably, however, recovery of the lighter
fractions produced by the thermal cracking process takes place
without feeding back the thermally cracked stream to the input 31
of the upgrader.
[0066] As shown in FIG. 3, the cooled, and pressure reduced
thermally cracked stream is applied to separator V18 which produces
two streams: at its overhead, a stream of thermal cracker
atmospheric distillate (fractions with atmospheric equivalent
boiling temperatures less than about 650.degree. F. and gases)
produced by the cracking process; and at its bottom, a stream of
thermal cracker atmospheric residue (i.e., a stream of that which
remains after atmospheric distillate is removed from the thermally
cracked feed to the separator). The fluid flowing out the overhead
of this separator is further cooled in heat exchanger E23 before
entering separator V19 which serves to separate the feed into a
vapor stream containing some atmospheric distillate and gas, and a
liquid stream containing atmospheric distillate all produced by the
thermal cracking process. The liquid stream of atmospheric
distillate from separator V19 is supplied to heat exchanger E19
(FIG. 2A) where cooling takes place before this stream is delivered
to condenser E20 to join the virgin atmospheric distillate
contained in feed 31.
[0067] The vapor stream from separator V19 may be cooled in heat
exchanger E25 for the purpose of preheating solvent for application
to turbine T, and then condensed in condenser E26. After pressure
reduction in a reducer valve, the overhead fluid from separator V19
flows to separator V20 which allows the non-condensable gases
produced by the thermal cracking process to be drawn out the
overhead of this separator and supplied, for example, to heater H2.
The bottom fluid from separator V20, atmospheric distillate
produced by the thermal cracking process, is delivered by pump P14
to heat exchanger E27 where it cools the output of mixer M2 before
being an input to this mixer.
[0068] The other input to mixer M2 is the heaviest portions of the
thermal cracker atmospheric residue stream produced at the bottom
of separator V18. Such stream is applied to vacuum fractionator V21
which produces two streams: at its overhead, a stream of thermal
cracker vacuum distillate (i.e., fractions with atmospheric
equivalent boiling points in the range 650-1000.degree. F.)
produced by the thermal cracking process; and at its bottom, a
stream of thermal cracker vacuum residue (i.e., a stream of that
which remains after vacuum distillate is removed from the thermal
cracker atmospheric residue feed to the separator). The thermal
cracker vacuum residue contains by-product asphaltenes, unconverted
DAO, etc. Superheated steam may be injected into separator V21 to
assist in the fractionation process.
[0069] Pump P15 delivers a stream of thermal cracker vacuum residue
to mixer M2 wherein the stream is mixed with thermal cracker
atmospheric distillate to produce a mixture that is cooled in heat
exchanger E27, and heated as needed in heat exchanger E28 before
being delivered to mixer M3. In this mixer, the heated mixture is
combined with virgin asphaltenes in feed 31 delivered to mixer M3
by pump P5 at the outlet of stripper V6 (FIG. 2A) of evaporation
section 38 of SDA unit 18'. The output of mixer M3 is a fuel oil
blend that is comparable to conventional fuel oil produced by
refineries by blending diesel fuel with the asphaltene product
produced by an SDA unit.
[0070] The present invention also contemplates other uses for the
thermal cracker atmospheric distillate produced at the overhead of
separator V18, the thermal cracker atmospheric residue produced at
the bottom of separator V18, and the vacuum thermally cracked
stream, and the thermal cracker vacuum residue produced at the
bottom of fractionator V21. For example, instead of producing a
fuel oil blend, these components can be used to produce asphalt
cement or asphalt cement binder.
[0071] The upgrader shown and described in FIGS. 2A, 2B, and 3
receives crude oil at its input at 31, and produces at point Z
valuable light hydrocarbons (e.g., naphtha, virgin and thermal
cracker produced atmospheric distillates, and virgin and thermal
cracker produced vacuum distillates) for tankage or pipeline
utilization, and at point Y, a fuel oil blend of the heavy residual
material that remains after the valuable light hydrocarbons are
removed from the feed. However, instead of storing or transporting
the valuable light hydrocarbons produced by the upgrader apparatus,
they may be directly used for power generation purposes as
illustrated in FIGS. 4A, 4B, 5, 6 and 7.
[0072] In apparatus 50 shown in FIG. 4A, upgrader 30A is
constructed in accordance with the present invention and receives
hydrocarbon feed 51 which may be crude oil, vacuum resid from a
refinery, or other heavy hydrocarbon. Upgrader 30A produces two
main outputs from this single input: non-asphaltene product stream
52, which comprises light, valuable hydrocarbons (e.g., atmospheric
and vacuum distillates, etc.) produced as described above, and
asphaltene product stream 53. Some or all of stream 52 is piped to
prime mover 54 which may be, for example, an internal combustion
engine such as a diesel engine, gas engine, or a gas turbine, etc.,
coupled to a generator (not shown) for generating power by using
stream 52 as a fuel and producing hot exhaust gases in conduit
55.
[0073] Some or all of asphaltene stream 53 is directed to combustor
56 wherein combustion takes place producing hot products of
combustion in conduit 57. Both all, or some of the exhaust from the
prime mover and the hot products of combustion from the combustor
are applied to steam boiler 58 which generates steam that is
applied to steam turbine 59 for generating additional power. The
heat depleted gases that exit the steam boiler are conveyed to a
stack which may contain scrubber 60 that removes environmentally
deleterious components such as sulfur before the heat depleted
gases are vented to the atmosphere.
[0074] In apparatus 70 shown in FIG. 4B, upgrader 30A is
constructed in accordance with the present invention and receives
hydrocarbon feed 51 which may be crude oil, vacuum resid from a
refinery, or other heavy hydrocarbon. Upgrader 30A produces two
main outputs from this single input: non-asphaltene product stream
52, which comprises light, valuable hydrocarbons (e.g., atmospheric
and vacuum distillates, etc.) produced as described above, and
asphaltene product stream 53. Some or all of stream 52 is piped to
prime mover 54 which may be, for example, an internal combustion
engine such as a diesel engine, gas engine, or a gas turbine, etc.,
coupled to a generator (not shown) for generating power by using
stream 52 as a fuel and producing hot exhaust gases in conduit
55.
[0075] All or some of the exhaust gases are applied to fluidized
bed combustor 71 (which, if preferred, may be a spouted bed
combustor) as combustion air, or as a fluidizing medium, or as both
as combustion air and as a fluidizing medium. The fuel for
combustor 71 is the asphaltene in stream 53 produced by the
upgrader. The hot combustion gases produced by the fluidized bed
combustor are applied to steam boiler 72 which generates steam that
is applied to steam turbine 73 which generates additional power.
The heat depleted gases that exit the steam boiler are conveyed to
a stack which may contain scrubber 74 that removes environmentally
deleterious components such as sulfur before the heat depleted
gases are vented to the atmosphere.
[0076] In apparatus 80 shown in FIG. 5 is a variant of the
apparatus shown in FIG. 4B in that FIG. 5 shows gas turbine unit
54A as the prime mover. Unit 54A includes compressor 81 for
compressing ambient air and producing a compressed air stream that
is applied to burner 82 in which is burned a non-asphaltene product
from the upgrader. Burner 82 produces a heated stream of gas that
is applied to turbine 83 coupled to generator 84. The heated stream
of gas expands in turbine 83 driving the generator and producing
power and exhaust gases. All or some of these exhaust gases are
supplied to fluidized bed combustor 85 as a fluidizing medium
and/or combustion air to support the combustion of asphaltene
product produced by the upgrader.
[0077] Heat exchanger 86 interposed between compressor 81 and
burner 82 is operatively associated with combustor 85 (which may be
a fluidized bed combustor, or spouted bed combustor) for
transferring heat from the combustor to the compressed air stream
produced by the compressor. The hot combustion gases produced by
combustor 84 are applied to steam boiler 87 which generates steam
that is used by steam turbine 88 to generate additional power. The
heat depleted gases that exit the steam boiler are conveyed to a
stack which may contain scrubber 89 that removes environmentally
deleterious components such as sulfur before the heat depleted
gases are vented to the atmosphere.
[0078] In apparatus 90 shown in FIG. 6, both an air turbine and a
gas turbine are the prime movers that use the non-asphaltene
product stream produced by upgrader 30A. Gas turbine unit 91 of
apparatus 90 includes compressor 92 for compressing ambient air and
producing a compressed air stream, and burner 93 to which the
compressed air stream is supplied and to which is supplied a
non-asphaltene product from the upgrader. Burner 93 heats the air
producing a heated stream of gas that is applied to gas turbine 94
coupled to generator 95. The heated stream of gas expands in
turbine 94 which drives the generator producing power and exhaust
gases which are applied to waste heat boiler 103 for producing
steam.
[0079] Apparatus 90 also includes air turbine unit 96 having
compressor 97 for compressing ambient air and producing a
compressed air stream, and heat exchanger 98 for heating the air
and producing a heated stream of air. Air turbine 99 coupled to
generator 100 is responsive to the heated stream of air for driving
the generator and producing power and a heat-depleted stream of
air. Combustor 101, configured as a fluidized bed combustor, or
spouted bed combustor, combusts asphaltenes from the product stream
of asphaltenes produced by said upgrader, and produces combustion
gases.
[0080] Heat exchanger 98 is operatively associated with and
responsive to combustor 101 for supplying heat to the air stream
compressed by compressor 97. As indicated, the heat-depleted stream
of air exhausted by turbine 99 supplies all, or some of the air for
fluidizing the combustor. Finally, steam boiler 102 is responsive
to the combustion gases from the combustor for generating steam,
which together with steam from waste heat boiler 103, is supplied
to steam turbine 104 for generating additional power.
[0081] Optionally, oil shale, low grade coal, or other material,
e.g., limestone, containing substantial amounts of calcium
carbonate, can be combusted in the combustors shown in FIGS. 4A,
4B, 5, and 6 for effecting the capture of sulfur compounds in the
asphaltene product stream burned in the various combustors. In a
further embodiment of the invention shown in FIG. 7, waste heat
produced by a power generating system, such as a system that
includes a prime mover such as a combustion turbine, and/or
internal combustion engines (e.g., diesel engine, gas engine,
etc.), or a combined cycle system having a steam turbine, can be
utilized to provide process heat for a conventional solvent
deasphalting unit, or for the upgraders disclosed in this
application.
[0082] When gases from the prime mover are added to the combustor
or steam boiler, pollutants (e.g., sulfur, etc.) of both streams
can be treated using a common system, e.g., by adding limestone,
oil shale, low grade fuel, etc. to the combustor. In such a manner,
sulfur rich fuel can be used in the gas turbine, the sulfur being
treated in the combustor to which all or a portion of the exhaust
gases of the gas turbine are added.
[0083] The advantages and improved results furnished by the method
and apparatus of the present invention are apparent from the
foregoing description of the preferred embodiments of the
invention. Various changes and modifications may be made without
departing from the spirit and scope of the invention as described
in the appended claims.
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