Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
HEAVY OIL UPGRADING APPARATUS AND HEAVY OIL UPGRADING METHOD
TECHNICAL FIELD
[0001]
The present invention relates to a technique for heavy
oil upgrading by using supercritical water.
BACKGROUND ART
[0002]
As crude oil consumption is predicted to increase, in
particular in developing countries such as China and India,
the production of light crude oil that has been conventionally
used has peaked, and the necessity of using heavy crude oil
or ultra-heavy crude oil that has not been heretofore used is
growing. Even in the field of ultra-heavy oil, cost-efficient
production technologies have already been established for oil
sand bitumen in Canada and Orinoco tar in Venezuela and the
production volumes have been increasing.
[0003]
These ultra-heavy crude oils have extremely high density
and viscosity. Therefore, pipelines cannot be directly used
for transporting the oils from the wells at the production sites
to the refineries at the consumption site. For this reason,
two methods are selected for use at a well site: a dilution
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method by which a diluting agent is mixed to reduce the
viscosity and an upgrading method by which a plant that is
called "upgrader" is constructed nearby for conducting thermal
cracking and hydrogenation treatment and a light synthetic
crude oil is produced.
[0004]
However, the following problems are associated with the
dilution method. Thus, it
is necessary to ensure the
sufficient amount of a diluting agent such as condensate and
the transportation cost is increased because the amount to be
transported is increased by dilution. Problems are also
associated with the upgrading method. Thus, since a
large-scale plant that is as large as a refinery is necessary
at the well site, such a construction is cost efficient only
in the vicinity of large-scale oil fields. Further,
byproducts such as coke and sulfur have to be treated and the
supply of hydrogen necessary for upgrading has to be ensured.
[0005]
Thermal cracking processes such that use a delayed coker
and a fluid coker and hydrogenation cracking processes such
as H-Oil and LC-Finings are presently available as heavy oil
upgrading techniques. In the thermal cracking process, the
heavy oil is thermally cracked and the cracked oil, gas and
coke are produced. The problem is that byproducts such as coke
and sulfur that are generated in large quantities in this
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process often have to be disposed of in unused areas.
[0006]
The hydrogenation cracking process is a technique for
heavy oil cracking by using a catalyst under high-temperature
and high-pressure hydrogen conditions. In this case, a large
amount of hydrogen is necessary and therefore naphtha or
natural gas is required. Therefore, a problem is associated
with supply thereof. In addition, the supplies of catalyst
and spent catalyst wastes also have to be taken into account.
As described hereinabove, with the presently available
technology, problems are associated with processing of
byproducts, production of hydrogen, supply of catalyst, and
processing of spent catalysts.
[0007]
In order to resolve the above-described problems, the
inventors of the present application focused there attention
on a technique for upgrading a heavy crude oil or ultra-heavy
crude oil (referred to hereinbelow as "heavy oil") by using
supercritical water and producing synthetic crude oil that can
be transported in pipelines, without using a diluting agent,
by a simple upgrading scheme. With this technique,
pipeline-transportable synthetic crude oil can be obtained by
advancing in parallel a thermal cracking reaction of heavy oil
that is induced by contact of the heavy oil with supercritical
water and extraction of the light oil fraction generated by
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, 1
the thermal cracking into the supercritical water in a reactor
and separating and recovering the extracted light oil fraction.
The heavy residual oil fraction that has not been extracted
into the supercritical water can be used as residual oil for
applications such as a boiler fuel.
[0008]
For example, Patent Document 1 describes a technique of
supplying heavy oil vertically downward from the top of a
reactor, supplying supercritical water (or subcritical water)
from below and bringing the two into contact and upgrading
inside the reactor, thereby separating the heavy oil into a
light oil fraction that has been dissolved in the supercritical
water and a heavy residual oil fraction that has not been
dissolved therein, as a technique for upgrading heavy oil by
using supercritical water.
[0009]
Further, Patent Document 2 suggests an upgrading
apparatus having a primary thermal cracking unit in which heavy
oil is heated and mixed with supercritical water in the lower
portion inside a vertical reactor and part of a starting
material is cracked into a light component and gasified and
a secondary cracking unit that is suspended inside the reactor
above the central portion thereof in the up-down direction and
serves to crack further part of the gasified light component
into an upgraded component at a high temperature. In the
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1
primary thermal cracking unit, a thermal cracking container
is provided inside the reactor and the heavy oil is reacted
inside thereof. The liquid that overflows from the thermal
cracking container, without being thermally cracked, is
discharged as residual oil from the lower portion of the reactor.
Further, Patent Document 3 discloses a technique for reacting
heavy oil with supercritical water inside a reactor, generating
upgraded oil emulsion and coke, withdrawing the upgraded oil
emulsion in a continuous mode and withdrawing the coke in an
intermittent mode.
Citation List
Patent Documents
[0010]
Patent Document 1: Japanese Patent No. 4171062: claim
1, paragraphs [0030]-[0033], FIG. 1.
Patent Document 2: JP-A-2008-208170: claim 1, paragraphs
[0012]-[0017], FIG. 1.
Patent Document 3: JP-A-2007-51224: claim 1, paragraphs
[0024]-[0030], FIG. 3.
SUMMARY
Problem to be solved by the Invention
[0011]
With the technique described in Patent Document 1, from
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among the above-described prior art, heavy oil is brought into
contact with supercritical water and a light oil fraction is
dissolved in the supercritical water, thereby removing heavy
metals such as vanadium contained in the heavy oil and obtaining
gas turbine fuel that hardly causes high-temperature corrosion.
In this case, heavy metals contained in the heavy oil are
concentrated in the heavy residual oil fraction that is not
dissolved in the supercritical water and this heavy residual
oil fraction is used as fuel for a boiler or the like.
[0012]
Further, the description of Patent Document 1 (paragraph
[0012] ) indicates that although upgrading advances when heavy
oil is brought into contact with supercritical water, the
technique is focused on dissolving the light oil fraction in
the supercritical water and the heavy oil that is not dissolved
therein is precipitated and separated without being further
upgraded. Therefore, Patent Document 1 does not disclose a
technique of upgrading the heavy residual oil fraction that
has not been dissolved in the supercritical water, reducing
density or viscosity, and producing synthetic crude oil.
[0013]
Further, with the technique described in Patent Document
2, the primary thermal cracking unit is heated to a temperature
of 380 C-450 C, and the secondary thermal cracking unit that
is located above the primary thermal cracking unit is heated
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to a temperature of 450 C-550 C, which is higher than that of
the primary thermal cracking unit, whereby the cracking is
conducted in two stages: the heavy oil that has been brought
into contact with the supercritical water is cracked into a
light oil fraction and then into an upgraded component.
However, where the cracking of the light component is actively
advanced as by the above-described technique, the amount of
gas generated due to overcracking increases (liquid yield is
decreased) or the concentration of olefins in the light
component is raised. Therefore, this technique is not
suitable for producing synthetic crude oil.
[0014]
Further, Patent Document 2 (paragraph [0018] ) indicates
that the reaction time of heavy oil inside the thermal cracking
container disposed in the primary thermal cracking unit is
adjusted by changing the supplied amount of heavy oil or volume
of the thermal cracking container, and the reaction time in
the secondary thermal cracking unit is adjusted by changing
the flow rate of heavy oil or packing a filler into the secondary
thermal cracking unit and changing the internal volume thereof.
[0015]
The description of Patent Document 2 does not disclose,
for example, a space between the primary thermal cracking unit
and the secondary thermal cracking unit or a gap between the
thermal cracking container disposed inside the reactor of the
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primary thermal cracking unit and the reactor, or temperature
conditions in the bottom portion of the reactor where the liquid
that overflowed from the thermal cracking container is retained.
However, the cracking reaction and polymerization reaction of
light component and liquid that come into contact with the space
with a temperature reaching for example 380 C-550 C and flow
therein apparently proceed in the space, and the reaction
proceeding inside the reactor is difficult to control
sufficiently with the above-described methods.
[0016]
With the technique described in Patent Document 3, the
operations are conducted by selecting conditions under which
coke is actively generated and processing the generated coke
causes problems. Further, the increase in gas generation
(decrease in liquid yield) caused by overcracking of light oil
and increase in olefin concentration in the upgraded oil
require attention under severe conditions such that cause coke
generation.
[0017]
The present invention has been created to resolve the
above-described problems and it is an object thereof to provide
a heavy oil upgrading apparatus and upgrading method that make
it possible to control the advance degree of thermal cracking
of heavy oil when heavy oil is upgraded by using supercritical
water.
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[0018]
A heavy oil upgrading apparatus according to one aspect
of the present invention includes:
a reactor that is maintained at a temperature and a
pressure equal to or higher than critical points of water and
in which a heavy oil and supercritical water are brought into
contact with each other and the heavy oil is separated into
a first phase composed of a heavy residual oil fraction obtained
by thermal cracking and supercritical water dissolved in the
heavy residual oil fraction and a second phase composed of the
supercritical water and a light oil fraction extracted into
the supercritical water, while advancing thermal cracking of
the heavy oil;
a heavy oil supply unit that supplies the heavy oil into
the reactor;
a supercritical water supply unit that supplies the
supercritical water into the reactor;
a first withdrawing unit that withdraws a mixed fluid
of the heavy residual oil fraction and the supercritical water
from the first phase;
a second withdrawing unit that withdraws a mixed fluid
of the supercritical water and the light oil fraction from the
second phase;
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,
an interface detection unit that detects a height
position of an interface between the first phase and the second
phase in the reactor, and
a control unit that finds a volume of the first phase
on the basis of the height position of the interface detected
by the interface detection unit and controls the withdrawn
amount of the mixed fluid of the heavy residual oil fraction
and the supercritical water on the basis of the volume of the
first phase so that a residence time of the mixed fluid of the
heavy residual oil fraction and the supercritical water
dissolved in the heavy residual oil fraction becomes a first
residence time that has been set in advance.
[0019]
A heavy oil upgrading apparatus according to another
aspect of the present invention includes:
a reactor that is maintained at a temperature and a
pressure equal to or higher than critical points of water and
in which a heavy oil and supercritical water are brought into
contact with each other and the heavy oil is separated into
a first phase composed of a heavy residual oil fraction obtained
by thermal cracking and supercritical water dissolved in the
heavy residual oil fraction and a second phase composed of the
supercritical water and a light oil fraction extracted into
the supercritical water, while advancing thermal cracking of
the heavy oil;
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a heavy oil supply unit that supplies the heavy oil into
the reactor;
a supercritical water supply unit that supplies the
supercritical water into the reactor;
a first withdrawing unit that withdraws a mixed fluid
of the heavy residual oil fraction and the supercritical water
from the first phase;
a second withdrawing unit that withdraws a mixed fluid
of the supercritical water and the light oil fraction from the
second phase, and
a control unit that controls the withdrawn amount of the
mixed fluid of the heavy residual oil fraction and the
supercritical water on the basis of the supplied amount of the
heavy oil so that a residence time of the mixed fluid of the
heavy residual oil fraction and the supercritical water
dissolved in the heavy residual oil fraction becomes a first
residence time that has been set in advance.
[0020]
The above-described heavy oil upgrading apparatuses may
include the following features:
(a) in order to inhibit the formation of coke in the heavy
residual oil fraction, the control unit controls the withdrawn
amount of the mixed fluid of the heavy residual oil fraction
and the supercritical water so that the first residence time
is equal to or longer than 3 min and equal to or shorter than
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95 min;
(b) the first residence time is a residence time in which
thermal cracking of the heavy oil is advanced within a range
in which a generated amount of coke is equal to or greater than
0 wt.% and equal to or less than 20 wt.% of the heavy residual
oil fraction;
(c) the first residence time is a residence time in which
thermal cracking of the heavy oil is advanced till a kinematic
viscosity of the heavy residual oil fraction at a temperature
of 350 C becomes equal to or less than 3.0 x 10-5 m2/s;
(d) the control unit finds a volume of the second phase
on the basis of the height position of the interface detected
by the interface detection unit and controls the supplied
amount of the supercritical water on the basis of the volume
of the second phase so that a residence time of the mixed fluid
of the supercritical water and the light oil fraction extracted
into the supercritical water becomes a second residence time
that has been set in advance;
(e) the control unit controls the supplied amount of the
supercritical water on the basis of the supplied amount of the
heavy oil so that a residence time of the mixed fluid of the
supercritical water and the light oil fraction extracted into
the supercritical water becomes a second residence time that
has been set in advance;
(f) in order to inhibit overcracking of the light oil
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t
fraction, the control unit controls the supplied amount of the
supercritical water so that the second residence time is equal
to or longer than 1 min and equal to or shorter than 25 min;
(g) the second residence time is a residence time in which
thermal cracking of the heavy oil is advanced within a range
in which an amount of gas generated by overcracking is equal
to or greater than 0 wt.% and equal to or less than 5 wt .% of
the heavy residual oil fraction;
(h) the second residence time is a residence time in which
thermal cracking of the heavy oil is advanced till a kinematic
viscosity of the light oil fraction at a temperature of 10 C
becomes equal to or less than 5.0 x 10-3 m2/s, and
(i) the heavy oil is selected from a heavy oil group
including oil sand bitumen, Orinoco tar, atmospheric residue
fraction, and vacuum residue fraction.
[0021]
A heavy oil upgrading method according to yet another
aspect of the present invention includes the steps of:
supplying a heavy oil into a reactor;
supplying supercritical water into the reactor;
maintaining the inside of the reactor at a temperature
and a pressure equal to or higher than critical points of water,
bringing the heavy oil and the supercritical water into contact
with each other, and separating the heavy oil into a first phase
composed of a heavy residual oil fraction obtained by thermal
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t
cracking and supercritical water dissolved in the heavy
residual oil fraction and a second phase composed of the
supercritical water and a light oil fraction extracted into
the supercritical water, while advancing thermal cracking of
the heavy oil;
withdrawing a mixed fluid of the heavy residual oil
fraction and the supercritical water from the first phase;
withdrawing a mixed fluid of the supercritical water and
the light oil fraction from the second phase;
detecting a height position of an interface between the
first phase and the second phase in the reactor, and
finding a volume of the first phase on the basis of the
height position of the interface detected by the interface
detection unit and controlling the withdrawn amount of the
mixed fluid of the heavy residual oil fraction and the
supercritical water on the basis of the volume of the first
phase so that a residence time of the mixed fluid of the heavy
residual oil fraction and the supercritical water dissolved
in the heavy residual oil fraction becomes a first residence
time that has been set in advance.
[0022]
A heavy oil upgrading method according to still another
aspect of the present invention includes the steps of:
supplying a heavy oil into a reactor;
supplying supercritical water into the reactor;
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maintaining the inside of the reactor at a temperature
and a pressure equal to or higher than critical points of water,
bringing the heavy oil and the supercritical water into contact
with each other, and separating the heavy oil into a first phase
composed of a heavy residual oil fraction obtained by thermal
cracking and supercritical water dissolved in the heavy
residual oil fraction and a second phase composed of the
supercritical water and a light oil fraction extracted into
the supercritical water, while advancing thermal cracking of
the heavy oil;
withdrawing a mixed fluid of the heavy residual oil
fraction and the supercritical water from the first phase;
withdrawing a mixed fluid of the supercritical water and
the light oil fraction from the second phase, and
controlling the withdrawn amount of the mixed fluid of
the heavy residual oil fraction and the supercritical water
on the basis of the supplied amount of the heavy oil so that
a residence time of the mixed fluid of the heavy residual oil
fraction and the supercritical water dissolved in the heavy
residual oil fraction becomes a first residence time that has
been set in advance.
[0023]
The above-described heavy oil upgrading methods may
include the following features:
(j) the first residence time is adjusted to a range of
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equal to or longer than 3 min and equal to or shorter than 95
min in order to inhibit the formation of coke in the heavy
residual oil fraction;
(k) the first residence time is a residence time in which
thermal cracking of the heavy oil is advanced within a range
in which a generated amount of coke is equal to or greater than
0 wt.% and equal to or less than 20 wt.% of the heavy residual
oil fraction;
(1) the first residence time is a residence time in which
thermal cracking of the heavy oil is advanced till a kinematic
viscosity of the heavy residual oil fraction at a temperature
of 350 C becomes equal to or less than 3.0 x 10-5 m2/s;
(m) a step is included of finding a volume of the second
phase on the basis of the height position of the interface
detected in a step of detecting a height position of an
interface between the first phase and the second phase in the
reactor and controlling the supplied amount of the
supercritical water so that a residence time of the mixed fluid
of the supercritical water and the light oil fraction extracted
into the supercritical water in the second phase becomes a
second residence time that has been set in advance;
(n) a step is included of controlling the supplied amount
of the supercritical water on the basis of the supplied amount
of the heavy oil so that a residence time of the mixed fluid
of the supercritical water and the light oil fraction extracted
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. .
into the supercritical water becomes a second residence time
that has been set in advance;
(o) the second residence time is adjusted to a range of
equal to or longer than 1 min and equal to or shorter than 25
min in order to inhibit overcracking of the light oil fraction;
(p) the second residence time is a residence time in which
thermal cracking of the heavy oil is advanced within a range
in which an amount of gas generated by overcracking is equal
to or greater than 0 wt.% and equal to or less than 5 wt.% of
the heavy residual oil fraction;
(q) the second residence time is a residence time in which
thermal cracking of the heavy oil is advanced till a kinematic
viscosity of the light oil fraction at a temperature of 10 C
becomes equal to or less than 5.0 x 10-3 m2/s;
[0024]
(r) a step is included of lowering a temperature and
lowering a pressure of the mixed fluid of the heavy residual
oil fraction and supercritical water that has been withdrawn
from the first phase and separating the heavy residual oil
fraction and water;
(s) a step is included of lowering a temperature of the
mixed fluid of the heavy residual oil fraction and
supercritical water that has been withdrawn from the first
phase and obtaining a fuel oil in a state in which a water
fraction is included in the heavy residual oil fraction;
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(t) the mixed fluid of the heavy residual oil fraction
and supercritical water that has been withdrawn from the first
phase includes the water fraction within a range of equal to
or higher than 3 wt.% and equal to or lower than 100 wt.% of
the heavy residual oil fraction;
(u) a step is included of lowering a temperature and
lowering a pressure of the mixed fluid of the supercritical
water and light oil fraction that has been withdrawn from the
second phase and separating the light oil fraction and water;
(v) a step is included of recovering water separated from
the heavy residual oil fraction or light oil fraction for reuse
as supercritical water to be supplied into the reactor;
(w) steps are included of lowering a temperature and
lowering a pressure of the mixed fluid of the heavy residual
oil fraction and supercritical water that has been withdrawn
from the first phase and separating the heavy residual oil
fraction and water;
lowering a temperature and lowering a pressure of the
mixed fluid of the supercritical water and light oil fraction
that has been withdrawn from the second phase and separating
the light oil fraction and water, and
mixing the heavy residual oil fraction and the light oil
fraction after separating from water, and
(x) the heavy oil is selected from a heavy oil group
including oil sand bitumen, Orinoco tar, atmospheric residue
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30802-4
fraction, and vacuum residue fraction.
[0024a]
Another aspect of the invention relates to a heavy
oil upgrading method comprising the steps of: supplying a heavy
oil into a reactor; supplying supercritical water into the
reactor; maintaining the inside of the reactor at a temperature
and a pressure equal to or higher than critical point of water,
bringing the heavy oil and the supercritical water into contact
with each other, and separating the heavy oil into a first
phase composed of a heavy residual oil fraction obtained by
thermal cracking and supercritical water dissolved in the heavy
residual oil fraction and a second phase composed of the
supercritical water and a light oil fraction extracted into the
supercritical water, while advancing thermal cracking of the
heavy oil; withdrawing a mixed fluid of the heavy residual oil
fraction and the supercritical water from the first phase;
withdrawing a mixed fluid of the supercritical water and the
light oil fraction from the second phase; detecting a height
position of an interface between the first phase and the second
phase in the reactor, finding a volume of the first phase on
the basis of the height position of the interface detected by
the interface detection unit and controlling the withdrawn
amount of the mixed fluid of the heavy residual oil fraction
and the supercritical water on the basis of the volume of the
first phase so that a residence time of the mixed fluid of the
heavy residual oil fraction and the supercritical water
dissolved in the heavy residual oil fraction becomes a first
residence time that has been set in advance, and finding a
volume of the second phase on the basis of the height position
of the interface detected in a step of detecting a height
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30802-4
position of an interface between the first phase and the second
phase in the reactor and controlling the supplied amount of the
supercritical water so that a residence time of the mixed fluid
of the supercritical water and the light oil fraction extracted
into the supercritical water in the second phase becomes a
second residence time that has been set in advance.
[0024b]
A still further aspect of the invention relates to a
heavy oil upgrading method comprising the steps of: supplying a
heavy oil into a reactor; supplying supercritical water into
the reactor; maintaining the inside of the reactor at a
temperature and a pressure equal to or higher than critical
point of water, bringing the heavy oil and the supercritical
water into contact with each other, and separating the heavy
oil into a first phase composed of a heavy residual oil
fraction obtained by thermal cracking and supercritical water
dissolved in the heavy residual oil fraction and a second phase
composed of the supercritical water and a light oil fraction
extracted into the supercritical water, while advancing thermal
cracking of the heavy oil; withdrawing a mixed fluid of the
heavy residual oil fraction and the supercritical water from
the first phase; withdrawing a mixed fluid of the supercritical
water and the light oil fraction from the second phase;
estimating a height position of an interface between the first
phase and the second phase in the reactor based on the
solubility of supercritical water in the heavy residual oil
fraction, the amount of heavy oil supplied per unit time and
the yields of the light oil fraction and the heavy residual oil
fraction; finding a volume of the first phase and the second
phase on the basis of the height position of the estimated
19a
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30802-4
. '
interface; controlling the withdrawn amount of the mixed fluid
of the heavy residual oil fraction and the supercritical water
on the basis of the found volume of the first phase so that a
residence time of the mixed fluid of the heavy residual oil
fraction and the supercritical water dissolved in the heavy
residual oil fraction becomes a first residence time that has
been set in advance, and controlling the supplied amount of the
supercritical water on the basis of the found volume of the
second phase so that a residence time of the mixed fluid of the
supercritical water and the light oil fraction extracted into
the supercritical water becomes a second residence time that
has been set in advance.
[0025]
According to the present invention, the heavy oil and
supercritical water are brought into contact with each other
inside the reactor, thereby separating these fluids into two
phases: the first phase (a phase composed of a mixed fluid of a
heavy residual oil fraction and the supercritical water
dissolved in the heavy residual oil fraction) and the second
phase (a phase composed of a mixed fluid of the supercritical
water and a light oil fraction extracted into the supercritical
water), and the withdrawn amount of the mixed fluid of the
heavy residual oil fraction and supercritical water is adjusted
so that the residence time of the mixed fluid constituting the
first phase in the first phase becomes a first residence time
that has been set in advance. As a result, the advance degree
of thermal cracking of the heavy residual oil fraction that
proceeds in the first phase can be controlled and the upgrading
apparatus can be operated under optimum conditions, for
example, maximum limit thermal cracking is conducted within a
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range in which the generation of coke from the heavy residual
oil fraction is inhibited or thermal cracking is conducted so
that a kinematic viscosity of the heavy residual oil fraction
is within a desired range.
19c
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BRIEF DESCRIPTION FO THE DRAWINGS
[0026]
FIG. 1 is a process flow diagram relating to the heavy
oil upgrading apparatus of the present embodiment.
FIG. 2 is an explanatory drawing illustrating the
configuration of a reactor provided in the upgrading apparatus.
FIG. 3 is a process flow diagram of a test apparatus of
an example.
FIG. 4 is an explanatory drawing illustrating an
interface of the first phase and the second phase formed inside
the reactor.
MODE FOR CARRYING OUT THE INVENTION
[0027]
First, the entire configuration of the heavy oil
upgrading apparatus of the present embodiment will be explained
with reference to the process flow diagram shown in FIG. 1.
The upgrading apparatus of the present embodiment is disposed
at a well site where high-density and high-viscosity crude oil
such as oil sand bitumen or Orinoco tar is produced and serves
to upgrade the heavy oil into a low-density and low-viscosity
synthetic crude oil.
[0028]
As shown in FIG. 1, the upgrading apparatus is provided
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with a first reactor in which a heavy oil and supercritical
water are brought into contact with each other and the heavy
oil is upgraded and separated into a heavy residual oil fraction
and a light oil fraction, a high-pressure separator 2 that
performs oil-water separation of the mixed fluid of the light
oil fraction and supercritical water that has flown out of the
reactor 1, for example, under pressure conditions identical
to the pressure inside the reactor 1, a low-pressure separator
3 that performs oil-water separation of the mixed fluid of the
light oil and water that has flown out of the high-pressure
separator 2, under pressure conditions lower than those of the
high-pressure separator 2, a flash drum 4 that performs
oil-water separation of the mixed fluid of the heavy residual
oil fraction and supercritical water that has flown out of the
reactor 1 under pressure conditions lower than those of the
reaction 1, and a recycle water tank 5 for recycling the water
after the oil-water separation.
[0029]
In the reactor 1, the heavy oil is thermally cracked by
bringing the heavy oil and supercritical water under elevated
temperature and increased pressure into, for example,
countercurrent flow contact. The reactor serves to separate
the light oil fraction and heavy residual oil fraction obtained
therein and withdraw the separated fractions. The reactor 1
is a pressure vessel with an internal cavity that is formed,
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. .
for example, in a columnar shape. A heavy oil supply line 110
for receiving the heavy oil from the heavy oil supply source
11 is connected, for example, to a side wall portion at the
upper side of the reactor. The heavy oil supply source 11 is
composed, for example, of a tank that stores the heavy oil.
[0030]
A heavy oil supply pump 111 that raises a pressure to
a value equal to or higher than 22.1 MPa, which is a critical
pressure of water, for example, to 25 MPa to 30 MPa and pumps
the heavy oil received from the heavy oil supply source 11
towards the reactor 1, a flow rate adjusting valve 112 that
adjusts the supplied amount of the heavy oil, and a heating
device 113 composed, for example, of a heating furnace and
serving to heat the heavy oil supplied to the reactor 1, for
example, to a temperature of 300 C-450 C are installed in the
heavy oil supply line 110. In order to prevent the heavy oil
from polycondensation in the heavy oil supply line 110 or
heating device 113, the heavy oil is supplied at a temperature
lower than the temperature (for example, 374 C-500 C) inside
the reactor 1. The heavy oil supply line 110, heavy oil supply
pump 111, flow rate adjusting valve 112, and heating device
113 correspond to a heavy oil supply unit of the present
embodiment.
[0031]
A supercritical water supply line 120 for supplying the
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water received from a water supply source 12 composed of a
storage tank or the like to the reactor 1 in a supercritical
state is connected, for example, to a side wall portion at the
lower side of the reactor. A supercritical water supply pump
121 that raises a pressure to a value equal to or higher than
a critical pressure of water (22.1 MPa), for example, to 25
MPa to 30 MPa, and pumps the water received from the water supply
source 12 towards the reactor 1, a flow rate adjusting valve
122 that adjusts the supplied amount of the supercritical water,
and a heating device 123 composed, for example, of a heating
furnace and serving to heat the supercritical water supplied
to the reactor 1, for example, to a temperature equal to or
higher than a critical temperature thereof (374 C), for example,
450 C-600 C are installed in the supercritical water supply
line 120. As described hereinabove, the heavy oil supplied
from the heavy oil supply line 110 is supplied at a temperature
lower than the temperature inside the reactor 1 with the object
of preventing the polycondensation. Therefore, where the
supercritical water is supplied from the supercritical water
supply line 120 at a temperature higher than the temperature
inside the reactor 1, heat necessary for a thermal cracking
reaction of the heavy oil is supplied to the reactor. The
supercritical water supply line 120, supercritical water
supply pump 121, flow rate adjusting valve 122, and heating
device 123 correspond to the supercritical water supply unit
23
CA 02774062 2012-03-13
of the present embodiment.
[0032]
A light oil fraction withdrawing line 130 for withdrawing
the mixed fluid formed by extraction of the light oil fraction
obtained by cracking of the heavy oil inside the reactor 1 into
the supercritical water is connected, for example, to the top
portion of the column of the reactor 1. A cooling device 132
composed of a heat exchanger or the like and serving to cool
the mixed fluid flowing in the light oil fraction withdrawing
line 130 to a temperature lower than a critical pressure of
water, for example, to 200 C-374 C and a pressure adjusting
valve 131 for adjusting the pressure inside the reactor 1 to,
for example, 25 MPa to 30 MPa are installed in the light oil
fraction withdrawing line 130. The light oil fraction
withdrawing line 130, pressure adjusting valve 131, and cooling
device 132 correspond to the second withdrawing unit of the
present embodiment.
[0033]
The high-pressure separator 2 for separating the mixed
fluid cooled in the cooling device 132 into a light oil fraction
(this light oil fraction also contains a water fraction) and
water under a pressure almost equal to the pressure inside the
reactor 1 is provided downstream of the light oil fraction
withdrawing line 130. A light oil fraction line 210 through
which the light oil fraction is withdrawn and pumped to the
24
CA 02774062 2012-03-13
low-pressure separator 3 is connected to the upper side of the
high-pressure separator 2. A cooling device 212 composed of
a heat exchanger or the like and serving to cool the light oil
fraction to a temperature about 40 C-100 C and a pressure
reducing valve 211 for reducing the pressure of the light oil
fraction flowing in the line 210, for example, to a pressure
of about 0.2 MPa to 1.0 MPa, which is higher than the normal
pressure, are installed in the light oil fraction line 210.
[0034]
A high-pressure separated water line 220 for withdrawing
the water separated from the light oil fraction under a pressure
of about 25 MPa to 30 MPa and temperature conditions of
200 C-374 C is provided at the bottom side of the high-pressure
separator 2. The high-pressure separated water line 220 is
connected to the below-described recycle water line 510, and
the separated water from the high-pressure separator 2 can be
supplied again to the reactor 1. A high-pressure separated
water recycle pump 221 installed in the high-pressure separated
water line 220 serves to pump the separated water from the
high-pressure separator 2.
[0035]
The low-pressure separator 3 provided at the downstream
side of the light oil fraction line 210 will be explained below.
The low-pressure separator 3 serves to conduct again the
separation of the light oil fraction and water under a pressure
CA 02774062 2012-03-13
of about 0.2 MPa to 1.0 MPa and a temperature conditions of
about 40 C-100 C with respect to the light oil fraction
including a water fraction and flowing out from the
high-pressure separator 2. The reference numeral 320 stands
for a synthetic crude oil line that withdraws the light oil
fraction separated from water, as a synthetic crude oil, into
the synthetic crude oil tank 62.
[0036]
A low-pressure separated water recycle line 330 is
connected, for example, to a bottom portion of the low-pressure
separator 3. The low-pressure separated water recycle line
330 serves to withdraw the water separated from the light oil
fraction and pump the withdrawn water as supercritical water
into the recycle water tank 5 for recycling. Further, a
discharged water line 340 through which part of the water that
will be recycled is withdrawn toward a discharged water
treatment equipment 63 branches off the low-pressure separated
water recycle line 330, and the concentration of oil fraction
or the concentration of salts in the recycle water that
circulates inside the upgrading apparatus can be adjusted to
a value equal to or lower than a predetermined value by
increasing or decreasing the amount of liquid pumped into the
discharged water treatment equipment 63. The reference
numeral 310 in the figure stands for a discharged gas line for
pumping the gas that has evaporated from the light oil fraction
26
CA 02774062 2012-03-13
into the discharged gas treatment equipment 61.
[0037]
Concerning the process flow in the column top system of
the above-described reactor 1, a heavy residual oil fraction
withdrawing line 140 for withdrawing the mixed fluid of a heavy
residual oil fraction that has not been extracted into the
supercritical water and the supercritical water that has been
dissolved in the heavy residual oil fraction, from among the
heavy oil cracked inside the reactor 1, is connected, for
example, to the column bottom portion of the reactor 1. A
cooling device 141 composed of a heat exchanger or the like
for cooling the mixed fluid flowing in the line 140 to a
temperature of about 200 C-350 C and a flow rate adjusting valve
142 serving to adjust the withdrawn amount of the mixed fluid
from the column bottom portion of the reactor 1 and reduce the
pressure of the mixed fluid flowing inside the heavy residual
oil fraction withdrawing line 140, for example, to about 0.2
MPa to 1.0 MPa, which is higher than the normal pressure, are
installed in the heavy residual oil fraction withdrawing line
140. The heavy residual oil fraction withdrawing line 140,
cooling device 141, and flow rate adjusting valve 142
correspond to the first withdrawing unit of the present
embodiment.
[0038]
The flow rate adjusting valve 142 is connected to the
27
CA 02774062 2012-03-13
=
flash drum 4, and the flash drum 4 plays a role of separating
the heavy residual oil fraction and water dissolved in the heavy
residual oil fraction under a pressure condition of 0.2 MPa
to 1.0 MPa and temperature conditions of about 200 C-350 C. A
drum separated water line 410 provided in the flash drum 4
serves to withdraw the water separated inside the flash drum
4 towards a low-pressure separated water recycle line 330 and
recycle the water. A residual oil line 420 serves to withdraw
the heavy residual oil fraction separated from water, for
example, as a residual oil for boiler combustion, into a
residual oil tank 64.
[0039]
A synthetic crude oil mixing line 430 for mixing the
entire amount of the heavy residual oil fraction withdrawn from
the flash drum 4, or part thereof, with the light oil fraction
withdrawn from the low-pressure separator 3 and pumping the
mixture to the synthetic crude oil tank 62 is branched off the
residual oil line 420. By mixing the heavy residual oil
fraction with the light oil fraction, it is possible to increase
the yield of the synthetic crude oil with an added value higher
than that of the boiler fuel. The amount of the heavy residual
oil fraction mixed with the light oil fraction is adjusted to
a mixed amount within a range in which compatibility of the
synthetic crude oil after mixing is ensured, in other words,
to a mixed amount within a range in which the synthetic crude
28
CA 02774062 2012-03-13
oil after mixing is not separated again into the heavy and light
oil fractions.
[0040]
For example, a CII (Colloidal Instability Index)
represented by Equation (1) below can be used as an index for
determining the compatibility of the synthetic crude oil. The
CII is found from Equation (1) by implementing, for example,
a SARA analysis with respect to the synthetic crude oil after
mixing the heavy and light oil fractions and measuring the
amounts of saturated hydrocarbons, aromatic hydrocarbons,
resins, and asphaltenes contained in the synthetic crude oil.
The mixed amount of the heavy residual oil fraction is adjusted
so that the CII value becomes equal to or less than 0.5.
CII = { (Saturated hydrocarbons + Asphaltenes) /
(Aromatic hydrocarbons + Resins)} 0.5 ... (1)
[0041]
A water recycle system for supercritical water will be
explained below.
The recycle water tank 5 provided downstream of the
low-pressure separated water recycle line 330 plays a role of
receiving the water separated from the light oil fraction in
the low-pressure separator 3 and the water separated from the
heavy residual oil fraction in the flash drum 4 and resupplying
the water collected in the recycle water tank 5 into the
supercritical water supply line 120. In the figures, the
29
CA 02774062 2012-03-13
reference symbol 510 stands for a recycle water line that
connects the recycle water tank 5 to the supercritical water
supply line 120, and 511 - a recycle water pump for raising
the pressure of water released from the recycle water tank 5,
for example, to 22.1 MPa to 40 MPa, which is equal to or higher
than the critical pressure (22.1 MPa), and pumping the water
towards the supercritical water supply line 120. Further, as
described hereinabove, the high-pressure separated water line
220 for recycling the water separated in the high-pressure
separator 2 merges with the recycle water line 510. By
recycling the water to be used as the supercritical water, it
is possible to reduce the amount of new water that is to be
used, easily ensure the amount of water necessary for heavy
oil upgrading, and also reduce an environmental load.
[0042]
As shown in FIG. 2, the upgrading apparatus includes a
control unit 7. The control unit 7 is composed, for example,
of a computer provided with a CPU and a storage unit. The
storage unit has recorded therein a program including a group
of steps (commands) of control relating to the operation of
the upgrading apparatus, that is, operations of bringing the
heavy oil and supercritical water into contact with each other
inside the reactor 1 and advancing thermal cracking, separating
into the heavy residual oil fraction and light oil fraction,
removing a water fraction contained in each oil fraction, and
CA 02774062 2014-01-08
30802-4
obtaining residual oil composed of the light oil fraction alone
or a synthetic crude oil in which the light oil fraction is
mixed with the heavy residual oil fraction, and the heavy
residual oil fraction. This program is stored in a storage
medium, for example, a hard disk, a compact disk, a
magnetooptical disk, and a memory card and installed therefrom
into the computer.
[0043]
The upgrading apparatus of the present embodiment for
which the entire process flow has been schematically described
hereinabove has a configuration that makes it possible to
regulate by using mutually independent operation variables:
(1) the control that decreases the kinematic viscosity of the
heavy residual oil fraction, while inhibiting the generation
of coke in the heavy residual oil fraction, and (2) the control
that decreases the kinematic viscosity of the light oil
fraction, while inhibiting the generation of gas that
accompanies overcracking of the light oil fraction. This
configuration will be described below in greater detail.
[0044]
FIG. 2 shows schematically the internal structure of the
aforementioned reactor 1 and the configuration of the control
system provided in the reactor 1. The heavy oil that has been
heated while passing through the heavy oil supply line 110 is
supplied from the upper side of the reactor 1, and the
31
CA 02774062 2012-03-13
supercritical water that has been heated while passing through
the supercritical water supply line 120 is supplied from the
bottom side of the reactor 1. When the two fluids come into
contact, thermal cracking of the heavy oil is advanced by the
heat carried by the supercritical water and the entire heavy
oil is converted into a lighter oil. The reference numeral
101 shown in FIG. 2 stands for a heavy oil supply nozzle and
102 - a supercritical water supply nozzle.
[0045]
Further, where the two fluids are brought into contact,
first, the light oil fraction that has been contained in the
heavy oil is extracted into the supercritical water, the heavy
residual oil fraction that has remained, without being
extracted into the supercritical water, is thermally cracked,
and the light oil fraction produced by the thermal cracking
is extracted into the supercritical water, thereby forming two
phases, namely, forming a continuous phase (referred to
hereinbelow as "second phase") composed of the supercritical
water and light oil fraction and a continuous phase (referred
to hereinbelow as "first phase") formed by the light oil
fraction that has not been extracted into the supercritical
water. Since the heavy residual oil fraction has a specific
gravity higher than that of the mixed fluid of the supercritical
water and light oil fraction, the first phase is formed in the
lower portion of the reactor 1 and the second phase is formed
32
CA 02774062 2012-03-13
in the upper portion of the reactor 1.
[0046]
In reality, the supercritical water in an amount of about
3 wt.% to 100 wt.% of the heavy residual oil fraction (based
on a dry weight in a state in which no water fraction is
contained) is dissolved in the heavy residual oil fraction
constituting the first phase, the actual amount of the
dissolved supercritical water depending on the type of heavy
oil and temperature and pressure conditions of the reactor 1.
From this standpoint, the first phase can be said to be
constituted by a mixed fluid of the heavy residual oil fraction
and supercritical water. As a result of such dissolution of
the supercritical water in the heavy residual oil fraction,
water molecules penetrate, for example, between molecules of
polycyclic aromatic hydrocarbons constituting the heavy
residual oil fraction that undergoes thermal cracking, and a
cage effect can be demonstrated by which the generation of
asphaltenes by polycondensation of polycyclic aromatic
hydrocarbons and the generation of coke by polycondensation
of asphaltenes are inhibited.
[0047]
In the reactor 1 of the present embodiment, the
supercritical water is supplied from the supercritical water
supply nozzle 102 into the first phase located in the lower
portion of the reactor, and the heavy oil is supplied from the
33
CA 02774062 2012-03-13
heavy oil supply nozzle 101 into the second phase located in
the upper portion. In this case, the extraction of the light
oil fraction into the supercritical water and the dissolution
of the supercritical water in the heavy residual oil fraction
proceed at an interface with the supercritical water (dispersed
phase) that rises in the first phase, an interface with the
heavy oil (dispersed phase) that settles in the second phase,
and a contact interface of the first phase and second phase.
[0048]
The inventors have established that the rise rate of the
supercritical water that rises in the first phase and the
sedimentation rate of the heavy oil that settles in the second
phase are extremely high and that the supercritical water and
heavy oil pass inside the first and second phases, for example,
in about several seconds to several tens of seconds. Therefore,
in the thermal cracking of heavy oil, the thermal cracking of
the heavy residual oil fraction actually proceeds in the first
phase, the light oil fraction generated as a result of such
thermal cracking is extracted into the second phase and thermal
cracking of the light oil fraction and the light oil fraction
supplied from the first phase further proceeds in the second
phase.
[0049]
The mixed fluid constituting the first phase is withdrawn
from the heavy residual oil fraction withdrawing line 140 and
34
CA 02774062 2012-03-13
cooled by the cooling device 141, whereby thermal cracking of
the heavy residual oil fraction is stopped. The mixed fluid
constituting the second phase is withdrawn from the light oil
fraction withdrawing line 130 and cooled by the cooling device
132, whereby thermal cracking of the light oil fraction is
stopped.
[0050]
According to the above-described thermal cracking
mechanism, the advance degree of thermal cracking of the heavy
residual oil fraction can be controlled by the residence time
of the mixed fluid of the heavy residual oil fraction in the
first phase and the supercritical water dissolved in this heavy
residual oil fraction (this mixed fluid will be referred to
hereinbelow as "effluent from first phase "). The yield of
the light oil fraction increases as thermal cracking of the
heavy oil advances. Further, by dissolving the supercritical
water in the heavy residual oil fraction and appropriately
advancing the cracking of the heavy residual oil fraction under
conditions at which the cage effect is demonstrated, the
viscosity of the heavy residual oil fraction is decreased and
the synthetic crude oil can be easily handled when used as a
boiler fuel or after mixing with the light oil fraction. Where
thermal cracking is advanced to a degree such that cancels the
aforementioned cage effect, coke is generated in the heavy
residual oil fraction.
CA 02774062 2012-03-13
,
[0051]
Accordingly, in the upgrading apparatus of the present
embodiment, a mechanism is provided that adjusts the residence
time of the effluent from first phase in the first phase so
that the kinematic viscosity, for example at 350 C, of the heavy
residual oil fraction that becomes a residual oil is equal to
or less than 3.0 x 10-5 m2/s (equal to or less than 30 cSt) and
so that thermal cracking of the heavy residual oil fraction
is advanced to a degree at which coke generation is inhibited.
[0052]
Concerning the advance degree of thermal cracking of the
light oil fraction, the residence time in the second phase of
the mixed fluid (referred to hereinbelow as "effluent from
second phase") of the supercritical water and the light oil
fraction extracted into the supercritical water can be adjusted.
The kinematic viscosity of the light oil fraction decreases
as thermal cracking advances and, for example, in cold climate
regions, the synthetic crude oil can be transported without
providing special heating equipment. However, where the light
oil fraction is overcracked, the amount of gas generated from
the light oil fraction increases and the yield of the synthetic
crude oil decreases.
[0053]
Accordingly, the present upgrading apparatus is provided
with a mechanism that adjusts the residence time of the effluent
36
CA 02774062 2012-03-13
from second phase in the second phase so as to obtain the
kinematic viscosity, for example at 10 C, of the light oil
fraction alone or a synthetic crude oil after mixing with the
heavy residual oil fraction, of equal to or less than 5.0 x
10-3 m/s (equal to or less than 5000 cSt) and so that thermal
cracking of the light oil fraction is advanced to a degree at
which coke generation is inhibited. In this case, in order
to obtain the kinematic viscosity of the synthetic crude oil
after mixing with the heavy residual oil fraction that is equal
to or less than 5.0 x 10-3 m2/s (equal to or less than 5000 cSt) ,
the second residence time is adjusted so that the kinematic
viscosity of the light oil fraction alone that will be mixed
with the heavy residual oil fraction having a comparatively
high kinematic viscosity assumes even lower value.
[0054]
For example, where the residence time of the effluent
from first phase in the first phase is denoted by ()pitch, the
residence time of the effluent from second phase in the second
phase is denoted by TA the amount of heavy oil supplied per
unit time from the heavy oil supply line 110 is denoted by Foin,
the amount of supercritical water supplied per unit time from
the supercritical water supply line 120 is denoted by Fwin, the
amount of the effluent from first phase that is withdrawn per
unit time from the heavy residual oil fraction withdrawing line
140 is denoted by Fwl+Pitchr and the amount of the effluent from
37
CA 02774062 2012-03-13
second phase that is withdrawn per unit time from the light
oil fraction withdrawing line 130 is denoted by Fw2 + Lt the
supply - withdraw balance of fluids in the reactor 1 can be
represented by the following Equation (2):
FOin + FWin = FW1+Pitch + FW2+Lt = = = ( 2 )
[0055]
The ratio of light oil fraction extracted into the second
phase varies depending on the state of heavy oil and also the
temperature and pressure conditions in the reactor 1 and the
advance degree of thermal cracking of the heavy residual oil
fraction. In the present example, a case will be considered
in which heavy oil is used such that a fraction lighter than
VGO (Vacuumed Gas Oil) with a boiling point of for example equal
to or lower than 540 C is extracted as a light oil fraction
into supercritical water and a fraction corresponding to VR
(Vacuumed Residue) with a boiling point higher than 540 C is
withdrawn as a heavy residual oil fraction that is not extracted
into the supercritical water. In the present embodiment, the
VG0 yield (that is, VR yield) is assumed to be handled as almost
constant by controlling pitch/ for example, within a variation
range of about 1 min of a target value and controlling the
advance degree of thermal cracking to at constant range.
[0056]
Where of the heavy oil supplied into the reactor 1, the
flow rate of a heavy residual oil fraction withdrawn therefrom
38
CA 02774062 2012-03-13
is denoted by Fpitch and the flow rate of a light oil fraction
withdrawn therefrom is denoted by FLt, and, of the supercritical
water supplied into the reactor 1, the flow rate of
supercritical water dissolving in the heavy residual oil
fraction and withdrawn from the first phase is denoted by Fw1r
and the flow rate of supercritical water extracting the light
oil fraction and withdrawn from the second phase is denoted
by Fw2, the withdrawn amounts of the first fluid and second fluid
can be represented by the following Equation (3) and Equation
(4) .
Fwl+Pitch = FW1 + FPitch = = = (3)
Fw2+Lt = Fw2 + FLt (4)
[0057]
Where the volume of the first phase in the reactor 1 is
denoted by V1 and the volume of the second phase is denoted
by V2 the residence time ()pitch of the effluent from first phase
in the first phase and the residence time OLt of the effluent
from second phase in the second phase can be represented by
the following Equation (5) and Equation (6) .
Opitch = V1 /Fwl+Pitch = V1/ ( Fw1 + FPitch ) = - - ( 5 )
OLt = V2 / FW2+Lt = V2 ( Fw2 + FLt) . . . ( 6 )
[0058]
(5) According to Equation (5) , when the volume V1 of the
first phase is constant, the residence time ()pitch of the effluent
from first phase in the first phase can be adjusted by
39
CA 02774062 2012-03-13
increasing or decreasing the withdrawn amount Fwl+Pitch of the
effluent from first phase from the heavy residual oil fraction
withdrawing line 140. The results of the below-described
examples have confirmed that in the upgrading apparatus of the
present embodiment, the generation of coke in the heavy
residual oil fraction can be inhibited and the kinematic
viscosity of the residual oil at a temperature of 350 C can
be controlled to a value equal to or less than 3.0 x 10-5 m2/s
(equal to or less than 30 cSt) by setting the residence time
Opitch within a range of "3 min pitch 95 min".
[0059]
Further, under constant temperature and pressure
conditions, the solubility of supercritical water in the heavy
residual oil fraction is constant. Therefore, where the flow
rate FPitch of the heavy residual oil fraction withdrawn from
the first phase is determined, the amount Fw1 of the
supercritical water dissolved in the heavy residual oil
fraction assumes a constant value. Where the supplied amount
Fwir, of the supercritical water is increased or decreased in
this state, the amount of supercritical water that is not
dissolved in the heavy residual oil fraction, that is, the
amount F2 of supercritical water forming the second phase can
be increased or decreased. The dissolved amount Fw1 of
supercritical water related to the amount Fpitch of the heavy
residual oil fraction that has flown out may be determined for
CA 02774062 2012-03-13
example by preliminary tests.
[0060]
The above-described relationships indicate that when the
volume V2 of the second phase is constant, Fw2 in Equation (6)
can be increased or decreased and the residence time OLt of the
effluent from second phase in the second phase can be adjusted
by increasing or decreasing the amount Fwin of the supercritical
water supplied from the supercritical water supply line 120.
The results of the below-described examples have confirmed that
in the upgrading apparatus of the present embodiment, the
generation of coke in the heavy residual oil fraction can be
inhibited and the kinematic viscosity at 10 C of the light oil
fraction alone or a synthetic crude oil after mixing with the
heavy residual oil fraction can be adjusted to a value equal
to or less than 5.0 x 10-3 m2/s (equal to or less than 5000 cSt)
by setting the residence time OLt within a range of "1 min OLt
< 25 min".
[0061]
On the basis of the above-described approach, a flow rate
controller 74 for adjusting the withdrawn amount Fwl+Pitch of the
effluent from first phase is provided in the heavy residual
oil fraction withdrawing line 140, and the indicated value (b)
of the flow rate controller 74 is outputted to the control unit
7. In the
control unit 7, the residence time pitch is calculated
on the basis of Equation (5) , and the flow rate set value (e)
41
CA 02774062 2012-03-13
of the flow rate controller 74 is increased or decreased and
the opening degree of the flow rate adjusting valve 142 is
adjusted so that the pitch assumes a preset target value.
[0062]
A flow rate controller 72 for adjusting the supplied
amount Fwin (that is, Fw2) is provided in the supercritical water
supply line 120, and the indicated value (a) of the flow rate
controller 72 is outputted to the control unit 7. In the
control unit 7, the residence time OLt is calculated on the basis
of Equation (6) , and the flow rate set value (d) of the flow
rate controller 74 is increased or decreased and the opening
degree of the flow rate adjusting valve 122 is adjusted so that
the OLt assumes a preset target value.
[0063]
In the reactor 1, an interface level meter 75, for example,
of differential-pressure, ultrasonic, or X-ray system that is
an interface detection unit of the present embodiment is
provided in the reactor 1, and a signal (c) that indicates
"Interface Level High" or "Interface Level Low", that is,
whether the level of the interface of the first phase and second
phase inside the reactor 1 is above or below a preset range,
is outputted to the control unit 7. The control unit 7 is
configured to maintain the volume V1 of the first phase (that
is, the volume V2 of the second phase) constant by increasing
or decreasing the flow rate set value (f) of the flow rate
42
CA 02774062 2012-03-13
controller 71 provided in the heavy oil supply line 110 and
adjust the supplied amount Foin of the heavy oil so as to return
the interface level to a height position within the set range.
The pressure inside the reactor is controlled by a
pressure controller (not shown in the figure) provided in the
light oil fraction line 210 of the high-pressure separator 2
shown in FIG. 1 by opening and closing a pressure reducing valve
211.
[0064]
The operation of adjusting the residence times pitch, OLt
in the upgrading apparatus of the above-described
configuration will be described below. Where the residence
time pitch of the effluent from first phase in the first phase
is assumed to surpass a set value, the pitch can be reduced and
returned to the set value by increasing the withdrawn amount
Fpitcn of the effluent from first phase according to Equation
(5) . However, where FPitch is increased, the interface level
is decreased. Therefore, an "Interface Level Low" signal is
outputted from the interface level meter 75, the flow rate
adjusting valve 112 is actuated, and the supplied amount Foin
of heavy oil from the heavy oil supply line 110 is increased.
[0065]
In the increase AFoin of the supplied amount of heavy oil,
"AFpitcn" is distributed to the first phase, but "AFLt" is
distributed to the second phase. As a result, as follows from
43
CA 02774062 2012-03-13
Equation (6) , OLt decreases, but this variation can be
compensated by reducing the supplied amount Fwin (that is, Fw2)
of the supercritical water to increase OLt and return it to the
set value.
[0066]
Where the residence time OLt of the effluent from second
phase in the second phase is assumed to surpass a set value,
the OLt is reduced and returned to the set value by increasing
the supplied amount FWin (that is, Fw2) of the supercritical
water according to Equation (6) . Even if Fwin is increased,
the withdrawn amount Fw2 + Lt from the second phase is increased
to match the increase in Fwin (F2), for example, so as to obtain
a constant pressure inside the reactor 1, and the interface
of the first phase and second phase is maintained at a constant
level.
[0067]
With the upgrading apparatus according to the present
embodiment, the heavy oil and supercritical water are separated
into two phases, namely, a first phase (a phase composed of
a heavy residual oil fraction and supercritical water dissolved
in the heavy residual oil fraction) and a second phase (a phase
composed of the supercritical water and a light oil fraction
that has been extracted into the supercritical water) by
bringing the two fluids into contact inside the reactor, and
the withdrawn amount of a mixed fluid (effluent from first
44
CA 02774062 2012-03-13
phase) of the heavy residual oil fraction and supercritical
water is adjusted so that a residence time of the mixed fluid
constituting the first phase in the first phase becomes the
first residence time (for example, set to a predetermined value
within a range of 3 min to 95 min) that has been set in advance.
As a result, the advance degree of thermal cracking of the heavy
residual oil fraction that proceeds in the first phase can be
controlled and the upgrading apparatus can be operated under
optimum conditions, for example, thermal cracking is conducted
within a range in which the generation of coke from the heavy
residual oil fraction is inhibited or thermal cracking is
conducted so that a kinematic viscosity of the heavy residual
oil fraction is within a desired range.
[0068]
Further, the withdrawn amount of the effluent from second
phase (mixed fluid of the light oil fraction and supercritical
water) is adjusted to that a residence time of the mixed fluid
constituting the second phase in the second phase becomes the
second residence time (for example, set to a predetermined
value within a range of 1 min to 25 min) that has been set in
=
advance. As a result, the advance degree of thermal cracking
of the light oil fraction that proceeds inside the second phase
can be controlled, thermal cracking is conducted within a range
in which, for example, the overcracking of the light oil
fraction is inhibited and gas generation is also inhibited,
CA 02774062 2012-03-13
and thermal cracking is conducted so that the kinematic
viscosity of the synthetic crude oil obtained from the light
oil fraction is within a desired range.
[0069]
In the example shown in FIG. 2, the interface level meter
75 is provided, the interface between the first and second
phases is measured, and V1 and V2 are made constant. However,
it is not necessary that the upgrading apparatus be provided
with the interface level meter 75. For example, it is also
possible to determine by preliminary tests the yields of the
light fraction and VR fraction from VG0 corresponding to the
type, temperature, and pressure conditions of the heavy oil,
estimate the interface level inside the reactor 1 from values
of Foinr Fwinr FPitchr FLt Fl, and F2, maintain constant volumes
V1, V2 on the basis of the estimated interface level, and adjust
the residence times ()pitch, OLt on the basis of Equations (5) and
(6) .
[0070]
In the examples shown in FIG. 2, constant volumes Vi,
V2 are maintained and the residence times pitch, OLt are adjusted,
but it is also possible to adjust the residence times n
-pitchr
OLt , while changing Vi, V2. For example, when the residence time
()pitch of the effluent from first phase in the first phase
surpasses the set value, pitch is reduced and returned to the
set value by increasing the withdrawn amount FPitch of the
46
CA 02774062 2012-03-13
effluent from first phase and reducing the volume V1 of the
first phase according to Equation (5) . As a result, the volume
V2 of the second phase is increased and the residence time OLt
of the effluent from second phase is affected. However, OLt
can be returned to the set value by increasing the supplied
amount Fwin of supercritical water (that is, Fw2) so as to
compensate the increase in volume V2
[0071]
In the above-described example, the residence time pitch
of the effluent from first phase in the first phase is adjusted
by the withdrawn amount FPitch of the effluent from first phase,
and the residence time Lt of the effluent from second phase
in the second phase is adjusted by the supplied amount Fwin of
supercritical water, but these residence times obviously can
be adjusted by other operation variables shown in Equation (5)
and Equation (6) , for example, the supplied amount Foin of heavy
oil and the withdrawn amount Fw2+Ltout of the effluent from second
phase.
[0072]
In the process flowchart shown in FIG. 1, an example is
illustrated in which water is separated from the heavy residual
oil fraction in the flash drum 4 and pumped as a residual oil
into the residual oil tank 64, but a configuration having no
flash drum 4 is also possible. For example, when the residual
oil is used as boiler fuel in a plant in the vicinity of the
47
CA 02774062 2012-03-13
upgrading apparatus, the flash drum 4 can be omitted. For
example, by obtaining the boiler fuel in a state in which a
water fraction is dispersed in the residual oil, without
subjecting the first fluid to pressure reduction, it is
possible to reduce further the viscosity of the residual fuel
and facilitate the handling of the residual fuel. At the same
time, under the effect of water dispersed in the residual oil,
vaporization during use as a boiler fuel is enhanced and
combustibility in the boiler can be improved.
[0073]
In the above-described embodiment, a case is explained
in which ultra-heavy crude oil such as oil sand bitumen or
Orinoco tar is processed as the heavy oil that is upgraded in
the upgrading apparatus, but the heavy oils that can be
processed in the present upgrading apparatus are not limited
to crude oil. For example, the upgrading processing of
atmospheric residue fraction and vacuum residue fraction is
also included in the technical scope of the present invention.
EXAMPLES
[0074]
Test 1
A test apparatus shown in FIG. 3 was fabricated as a model
apparatus of the upgrading apparatus shown in FIG. 1 and an
upgrading test of heavy oil was conducted.
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CA 02774062 2012-03-13
[0075]
A. Test Conditions
The reference numeral 200 in FIG. 3 stands for a
gas-liquid separation tank for separating the effluent from
second phase withdrawn from the upper side of the reactor 1
into gas and a mixed fluid of light oil fraction and water.
The reference numeral 143 stands for a ball valve for
withdrawing the heavy residual oil fraction (effluent from
second phase) from the lower side of the reactor 1. In the
present apparatus, the residence time ()pitch of the effluent from
first phase was controlled by the withdrawn amount Fpitch of the
residual oil, and the residence time OLt of the effluent from
second phase was controlled by the supplied amount Fwin of the
supercritical water. Oil sand bitumen produced in Canada and
having properties shown in Table I was used as the heavy oil.
Table 1
Density (g/cm3) 1.012
Kinematic viscosity at 40 C (m2/s) 1.7 x 10-2
[0076]
Example 1
The test was conducted under the following conditions.
Reaction temperature in the reactor 1: 430 C.
Reaction pressure in the reactor 1: 25 MPa.
Water/oil weight ratio: 1Ø
49
CA 02774062 2014-01-08
30802-4
Water/oil weight ratio: 1Ø
Residence time ()pitch of the effluent from first phase:
95 min.
Residence time Ou, of the effluent from second phase: 2.3
min.
Example 2
The test was conducted under the same conditions as in
Example 1, except:
Reaction temperature in the reactor 1: 450 C.
Residence time OPitch Of the effluent from first phase:
4.9 min.
Residence time OLtof the effluent from second phase: 11
min.
Example 3
The test was conducted under the same conditions as in
Example 1, except:
Residence time Opitch of the effluent from first phase:
32 min.
Residence time OLtof the effluent from second phase: 25
min.
Example 4
The test was conducted under the same conditions as in
Example 1, except:
Residence time Pitch of the effluent from first phase:
67 min.
CA 02774062 2014-01-08
. .
Comparative Example 1
The test was conducted under the same conditions as in
Example 1, except:
Residence time %itch of the effluent from first phase:
105 min.
Residence time OLtof the effluent from second phase: 1.1
min.
Test conditions of the examples and comparative example
are assembled in Table 2.
Table 2
Example 1 Example 2 Example 3 Example 4
---------------------------,
Comparative
Example 1
Reactor
430 450 430 430 430
temperature ( C)
Reactor pressure
25 25 25 25 25
(MPa)
Water/oil weight
1.0 1.0 0.5 1.0 1.0
ratio
Residence time
pad, of effluent
95 4.9 32 67 105
from first phase
(min)
Residence time Om
of effluent from 2.3 11 25 1.8 1.1
second phase (min) .
[0077]
B. Test Results
The yields of gas, synthetic crude oil (light oil
fraction), and residual oil (heavy residual oil fraction) in
the examples and comparative example are shown in Table 3. The
properties of the synthetic crude oil are shown in Table 4 and
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,
properties of the residual oil are shown in Table 5.
Table 3
.-----------------------------
Comparative
Example 1 Example 2 Example 3 Example 4
Example 1
Gas yield (wt.%) 4 2 3 1 -
Synthetic crude
74 60 63 63 -
oil yield (wt.%)
Residual oil Coking
22 38 34 36
yield (wt.%)
generation .
Table 4
Comparative
Example 1 Example 2 Example 3 Example 4
Example 1
Density
0.916 0.915 0.911 0.918 -
(g/cm3)
Kinematic
viscosity at 2.6 x 10-5 2.0 x 10-5 1.6 x 10-5 2.8 x 10-5 -
C (m2/s)
Table 5
Comparative
Example 1 Example 2 Example 3 Example 4
Example 1
Density
1.173 1.100 1.116 1.101 -
(g/cm3)
Kinematic
viscosity at 1.8 x 10-5 1.2 x 10-5 1.2 x 10-5 1.4 x 10 5 _
310 C (m2/s)
[0078]
Table 6 compares the results obtained in Examples 1 and
2 with the yield ratio of each fraction obtained as a result
of conducting a visbreaker test and a delayed coker test on
the oil sand bitumen identical to that used in Example 1. The
results in Examples 1 and 2 are obtained by combining the yield
ratios of the synthetic crude oil and residual oil and
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CA 02774062 2012-03-13
converting into the VG0 fraction with a boiling point equal
to or lower than 540 C and a VR fraction with a boiling point
higher than 540 C. Therefore, these results sometimes do not
match the yield ratio shown in Table 3.
Table 6
Delayed
Example 1 Example 2
Visbreaker
coker
Gas wt.% 3 2 7 2
VG0 fraction wt.% 74 67 75 64
Liquid
VR fraction wt.% 22 31 0 32
=
Coke wt.% 0 0 19 2
[0079]
According to the results of Example 1, as the first
residence time Opitch of effluent from first phase increases in
the sequence of Example 2 (Opitch: 4.9 min) -* Example 3 (Opitch:
32 min) -* Example 1 (Opitch: 95 min), the residual oil yield
decreases, but the synthetic crude oil yield increases.
Further, in Comparative Example 1 in which Opitch is 105 min,
coke generation (coking) was observed. The reason why the
residual oil yield is higher in Example 4 (Opitch: 67 min), in
which the first residence time ()pitch is longer than in Example
3, than in Example 3, but the synthetic crude oil yield is of
the same order as in Example 3 is not clear, but this is
apparently the result of the effect produced by a fluctuation
error.
[0080]
As for the gas yield, with the exception of Example 1
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CA 02774062 2012-03-13
in which the gas yield was the highest (OLt: 2.3 mm), the gas
yield tends to increase as the second residence time OLt
increases in the order of Example 4 (OLt: 1.8 min) ---> Example
2 (OLt: 11 min) ¨> Example 3 (OLt: 25 min) . The reason why the
highest gas yield of 4 wt.% is reached in Example 1 with the
second shortest second residence time OLt is not clear, but this
is apparently the result of the effect produced by a fluctuation
error.
[0081]
According to the results obtained by measuring the
kinematic viscosity of the synthetic crude oil shown in Table
4, a synthetic crude oil with a kinematic viscosity that caused
no practical problems, that is, a maximum kinematic viscosity
of 2.8 x 10-5 m2/s (28 cSt) at 10 C (standard value is 5.0 x
10-3 m2/s (5000 cSt) , was obtained in all the examples. In this
case, the kinematic viscosity of the synthetic crude oil tends
to decrease as the second residence time OLt increases in the
order of Example 4 (OLt: 1.8 min) ¨> Example 1 (OLt: 2.3 min)
¨> Example 2 (OLt: 11 min) ---> Example 3 (OLt: 25 min) . This is
apparently because the cracking of the light oil fraction
advances as the second residence time increases. This can be
also confirmed by the decrease in density of the synthetic crude
oil that follows the increase in the second residence time.
[0082]
According to the results obtained by measuring the
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CA 02774062 2012-03-13
kinematic viscosity of the residual oil shown in Table 5, a
residual oil with a kinematic viscosity that caused no
practical problems, that is, a maximum kinematic viscosity of
1.8 x 10-5m2/s (18 cSt) at 310 C, was obtained in all the examples.
The kinematic viscosity further decreased when the residual
oil was heated to 350 C. The kinematic viscosity of the
residual oil tends to increase following the increase in the
first residence time Opitch in the order of Example 2 (Opitch: 4.9
min) ¨> Example 3 (Opitch: 32 min) Example 4 (Opitch: 67 min)
¨> Example 1 (Opitch: 95 min) . This is apparently because the
polymerization of the heavy residual oil fraction advances
against the caged effect of the supercritical water that is
dissolved in the heavy residual oil fraction. This can be also
confirmed by the increase in density of the residual oil that
follows the increase in the first residence time.
[0083]
Combining the results of Examples 1 to 4 and Comparative
Example 1, when oil sand bitumen is used as a heavy oil serving
as a starting material, an easily handleable residual oil with
a kinematic viscosity of equal to or lower than 1.8 x 10-5 m2/s
(18 cSt) at 310 C is obtained, while inhibiting the coke
generation, if the first residence time Opitch is within a range
of 3 min to 95 min. Further, gas generation is inhibited to
a value of equal to or lower than about 4 wt.% and a synthetic
crude oil with a kinematic viscosity of equal to or lower than
CA 02774062 2012-03-13
2.8 x 10-5 m2/s (28 cSt) at 10 C is obtained when the second
residence time OLt is within a range of 1 min to 25 min.
[0084]
According to the results shown in Table 6, coke
generation has been inhibited and the yield ratio of the VG0
fraction has increased over that of visbreaker, and in Example
1, a VGO fraction yield ratio of about the same order as that
of a delayed coker was obtained. This result demonstrates that
thermal cracking of heavy oil that uses supercritical water
is a thermal cracking process in which a VG0 fraction (light
oil fraction) can be obtained at a high yield ratio, while
inhibiting the generation of coke and gas, by adequately
controlling the first and second residence times.
[0085]
Example 2
An observation window for internal observations was
provided in the reactor 1 of the test apparatus identical to
that of Example 1 and the separation of fluid inside the reactor
into the first phase and second phase and the formation of
interface were confirmed. The results obtained by
photographing the inside of the reactor 1 through the
observation window are shown in FIG. 4A and the schematic
diagram thereof is shown in FIG. 4B. According to the results
shown in FIG. 4A, the first phase composed of the heavy residual
oil fraction and supercritical water dissolved in the heavy
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residual oil fraction and the second phase composed of
supercritical water and the light oil fraction extracted into
the supercritical water were confirmed in the lower portion
of the reactor 1.
[Explanation of Reference Symbols]
[0086]
1 reactor
110 heavy oil supply line
112 flow rate adjusting valve
120 supercritical water supply line
122 flow rate adjusting valve
130 light oil fraction withdrawing line
131 pressure adjusting valve
140 heavy residual oil fraction withdrawing line
142 flow rate adjusting valve
2 high-pressure separator
3 low-pressure separator
4 flash drum
recycle water tank
7 control unit
71, 72, 74 flow rate controller
73 pressure controller
75 interface level meter
57
