Note: Descriptions are shown in the official language in which they were submitted.
- 1 -
METHOD FOR RECOVERING OIL BY HEATING, STIRRING AND
CENTRIFUGATION OF A CRUDE OIL SLUDGE
BACKGROUND OF THE INVENTION
Field of the Invention
[0001]
The present invention relates to a method for
recovering oil from in a crude oil sludge deposited in a
crude oil tank in which a crude oil is stored.
Description of the Related Art
[0002]
A crude oil sludge deposited in crude oil tanks, after
being taken out of the crude oil tanks, is generally
processed as industrial waste, but its disposal needs a high
cost. On the other hand, the crude oil sludge contains about
30 to 80% by volume of oil in many cases, and thus there is a
large need to recover oil in the crude oil sludge.
[0003]
Then, attempts have conventionally been made to
recover oil from a crude oil sludge by using a vacuum
distillation method, a heat separation method, a
centrifugal separation method or the like (for example,
International Publication No. W02012/141024, Japanese
Date recue / Date received 2021-11-02
cA029891002017-12-11
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Patent Laid-Open No. 3-226481, Japanese Patent Laid-Open No.
2004-243300).
[0005]
However, oil recovered from a crude oil sludge is of a
poor quality, and thus in the case where a good-quality
fuel is produced by using the oil as a stock oil, the
refining cost becomes high. Hence, oil recovered from a
crude oil sludge is often used directly as an inexpensive
fuel oil.
[0006]
Here, if oil recovered from a crude oil sludge is
mixed with a stock oil, the mixture becomes allowed to be
sold not as an inexpensive fuel oil but as a crude oil of a
higher price. Studies by the present inventors, however,
have revealed that oil recovered from a crude oil sludge is
low in fluidity and poor in compatibility with a crude oil,
and thus when the oil, as it is, is mixed with a crude oil,
a sludge is easily generated again.
[0007]
Therefore, an object of the present invention is to
provide a method for recovering oil in a crude oil sludge,
wherein even if the oil recovered from the crude oil sludge
is mixed with a crude oil, a sludge is unlikely to be
generated again.
CA 02989100 2017-12-11
- 3 - SUMMARY OF THE INVENTION
[0008]
The above-mentioned problem is solved by the following
present inventions.
That is, the present invention (1) provides a method
for recovering oil in a crude oil sludge, comprising:
a first step (1) of mixing a crude oil sludge (A) with
a crude oil (B) so that the proportion of the crude oil
sludge (A) to the sum of the crude oil sludge (A) and the
crude oil (B) becomes 20 to 95% by mass, and then heating
and stirring the mixture of the crude oil sludge (A) with
the crude oil (B) at 40 to 200 C to thereby obtain a heated
and stirred material of the crude oil sludge (A) and the
crude oil (B);
a second step (1) of centrifugally separating the
heated and stirred material at 40 to 200 C into a light
liquid and a heavy fraction to thereby obtain the light
liquid; and
a third step (1) of bringing the temperature of the
light liquid to a temperature equal to or higher than the
melting point thereof, and mixing the light liquid having
the temperature equal to or higher than the melting point
into a crude oil (C) in a crude oil transfer pipe, wherein
the temperature of the crude oil (C) is equal to or higher
than the temperature of the light liquid, or the
CA 089100 2017--11
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temperature of the crude oil (C) is lower than the
temperature of the light liquid and the difference between
the temperature of the light liquid and the temperature of
the crude oil (C) is 40 C or lower.
[0009]
Further the present invention (2) provides a method
for recovering oil in a crude oil sludge, comprising:
a first step (2) of heating a crude oil sludge (A) at
40 to 200 C to thereby obtain a heated material of the
crude oil sludge (A);
a second step (2) of centrifugally separating the
heated material at 40 to 200 C into a light liquid and a
heavy fraction to thereby obtain the light liquid; and
a third step (2) of bringing the temperature of the
light liquid to a temperature equal to or higher than the
melting point thereof, and mixing the light liquid having
the temperature equal to or higher than the melting point
into a crude oil (C) in a crude oil transfer pipe, wherein
the temperature of the crude oil (C) is equal to or higher
than the temperature of the light liquid, or the
temperature of the crude oil (C) is lower than the
temperature of the light liquid and the difference between
the temperature of the light liquid and the temperature of
the crude oil (C) is 40 C or lower.
[0010]
CA 089100 2017--11
- 5 - Further the present invention (3) provides a crude oil
(D), being obtained by carrying out:
a first step (1) of mixing a crude oil sludge (A) with
a crude oil (B) so that the proportion of the crude oil
sludge (A) to the sum of the crude oil sludge (A) and the
crude oil (B) becomes 20 to 95% by mass, and then heating
and stirring the mixture of the crude oil sludge (A) with
the crude oil (B) at 40 to 200 C to thereby obtain a heated
and stirred material of the crude oil sludge (A) and the
crude oil (B);
a second step (1) of centrifugally separating the
heated and stirred material at 40 to 200 C into a light
liquid and a heavy fraction to thereby obtain the light
liquid; and
a third step (1) of bringing the temperature of the
light liquid to a temperature equal to or higher than the
melting point thereof, and mixing the light liquid having
the temperature equal to or higher than the melting point
into a crude oil (C) in a crude oil transfer pipe, wherein
the temperature of the crude oil (C) is equal to or higher
than the temperature of the light liquid, or the
temperature of the crude oil (C) is lower than the
temperature of the light liquid and the difference between
the temperature of the light liquid and the temperature of
the crude oil (C) is 40 C or lower.
CA 02989100 2017-12-11
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Further the present invention (4) provides a crude oil
(E), being obtained by carrying out:
a first step (2) of heating a crude oil sludge (A) at
40 to 200 C to thereby obtain a heated material of the
crude oil sludge (A);
a second step (2) of centrifugally separating the
heated material at 40 to 200 C into a light liquid and a
heavy fraction to thereby obtain the light liquid; and
a third step (2) of bringing the temperature of the
light liquid to a temperature equal to or higher than the
melting point thereof, and mixing the light liquid having
the temperature equal to or higher than the melting point
into a crude oil (C) in a crude oil transfer pipe, wherein
the temperature of the crude oil (C) is equal to or higher
than the temperature of the light liquid, or the
temperature of the crude oil (C) is lower than the
temperature of the light liquid and the difference between
the temperature of the light liquid and the temperature of
the crude oil (C) is 40 C or lower.
[0012]
The present invention can provide a method for
recovering oil in a crude oil sludge, wherein even if the
oil recovered from the crude oil sludge is mixed with a
crude oil, a sludge is unlikely to be generated again.
CA 02989100 2017-12-11
- 7 - BRIEF DESCRIPTION OF THE DRAWING
[0013]
FIG. 1 is a view illustrating a mixing system of a
light liquid with a crude oil, used in Examples and
Comparative Examples.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014]
A method for recovering oil in a crude oil sludge
according to a first aspect of the present invention is a
method for recovering oil in a crude oil sludge,
comprising:
a first step (1) of mixing a crude oil sludge (A) with
a crude oil (B) so that the proportion of the crude oil
sludge (A) to the sum of the crude oil sludge (A) and the
crude oil (B) becomes 20 to 95% by mass, and then heating
and stirring the mixture of the crude oil sludge (A) with
the crude oil (B) at 40 to 200 C to thereby obtain a heated
and stirred material of the crude oil sludge (A) and the
crude oil (B);
a second step (1) of centrifugally separating the
heated and stirred material at 40 to 200 C into a light
liquid and a heavy fraction to thereby obtain the light
liquid; and
CA 02989100 2017-12-11
- 8 - a third step (1) of bringing the temperature of the
light liquid to a temperature equal to or higher than the
melting point thereof, and mixing the light liquid having
the temperature equal to or higher than the melting point
into a crude oil (C) in a crude oil transfer pipe, wherein
the temperature of the crude oil (C) is equal to or higher
than the temperature of the light liquid, or the
temperature of the crude oil (C) is lower than the
temperature of the light liquid and the difference between
the temperature of the light liquid and the temperature of
the crude oil (C) is 40 C or lower.
[0015]
The first step (1) in the method for recovering oil in
a crude oil sludge according to the first aspect of the
present invention is a step of mixing a crude oil sludge
(A) with a crude oil (B), and then heating and stirring the
mixture of the crude oil sludge (A) with the crude oil (B)
at 40 to 200 C to thereby obtain a heated and stirred
material of the crude oil sludge (A) and the crude oil (B).
[0016]
The crude oil sludge (A) in the first step (1) is a
sludge generated from in a stored crude oil and deposited
on the bottom of a crude oil tank. The crude oil sludge
(A) includes a crude oil sludge which is generated from a
crude oil cleared of solid contents, moisture and the like
cA029891002017-12-11
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after crude oil mining, and stored in a crude oil tank, and
before being shipped to oil production plants, and is
deposited on the bottom of the crude oil tank; a crude oil
sludge deposited on the bottom of a crude oil tank in a
crude oil tanker; and a crude oil sludge which is generated
from a crude oil in a crude oil tank for storage before
being refined in an oil production plant, and is deposited
on the bottom of the crude oil tank. The crude oil sludge
(A) may be generated from one crude oil, or may be
generated from a plurality of crude oils.
[0017]
The crude oil sludge (A) contains oil, asphaltene,
iron, sand, water and the like. The oil in the crude oil
sludge (A) is mainly paraffins and aromatic hydrocarbons
having 40 or more carbon atoms. Then, the oil in the crude
oil sludge (A) is a component to be recovered from in the
crude oil sludge (A) by the method for recovering oil in a
crude oil sludge according to the present invention.
[0018]
A method of taking out a crude oil sludge (A)
deposited in a crude oil tank outside the crude oil tank is
not especially limited, and examples thereof include a
method (COW: crude oil washing) in which after a crude oil
in the crude oil tank is extracted outside the crude oil
tank, a high-pressure crude oil is jetted against the crude
c.A029891002017-12-11
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oil sludge (A) deposited in the crude oil tank to crush or
partially dissolve the crude oil sludge (A), which is then
extruded outside the crude oil tank with the crude oil, and
a method in which after the crude oil in the crude oil tank
is extracted outside the crude oil tank, the crude oil
sludge (A) deposited in the crude oil tank is taken out by
manpower.
[0019]
The crude oil (B) to be mixed with the crude oil
sludge (A) is not especially limited, and may be a crude
oil before being cleared of solid contents, moisture and
the like after crude oil mining, and being stored in a
crude oil tank, may be a crude oil shortly after being
cleared of solid contents, moisture and the like after
crude oil mining, and starting to be stored in a crude oil
tank, and before generating a crude oil sludge, or may be a
supernatant crude oil in a crude oil tank after a crude oil
sludge is generated on the bottom of the crude oil tank
during a certain-period storage of the crude oil in the
crude oil tank. The crude oil (B) may be the same crude
oil as a crude oil as a generation source of the crude oil
sludge (A), or may be a crude oil different therefrom.
[0020]
When a crude oil sludge (A) is taken out of a crude
oil tank, and in the case where the crude oil sludge (A) is
c.A029891002017-12-11
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taken out by extruding the crude oil sludge (A) with a
crude oil outside the crude oil tank (for example, COW), a
material taken out of the crude oil tank is a mixture of
the crude oil sludge (A) with the crude oil used for taking
out the crude oil sludge (A), but in this case, the crude
oil used for taking out the crude oil sludge (A) is
included in the crude oil (B).
[0021]
The first step (1) first mixes a crude oil sludge (A)
with a crude oil (B) so that the proportion of the crude
oil sludge (A) to the sum of the crude oil sludge (A) and
the crude oil (B) becomes 20 to 95% by mass, preferably 40
to 90% by mass, and more preferably 60 to 90% by mass. If
the proportion of the crude oil sludge (A) to the sum of
the crude oil sludge (A) and the crude oil (B) is less than
the above range, the amount to be processed in the second
step (1) increases and the economic efficiency decreases;
and if the proportion exceeds the above range, the recovery
of oil from the crude oil sludge (A) becomes insufficient.
[0022]
Further when a crude oil sludge (A) is taken out of a
crude oil tank, in the case where the crude oil sludge (A)
is taken out by extruding the crude oil sludge (A) with a
crude oil outside the crude oil tank (for example, COW
washing), the crude oil used for taking out the crude oil
c.A029891002017-12-11
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sludge (A) is included in the crude oil (B), and the
proportion of the crude oil sludge (A) to the sum of the
crude oil sludge (A) and the crude oil (B) is calculated.
Hence, in this case, by using the crude oil in an amount
such that the proportion of the crude oil sludge (A)
deposited on the bottom of the crude oil tank to the sum of
the crude oil sludge (A) and the crude oil to be used for
taking out the crude oil sludge (A) is a predetermined
mixing proportion, that is, the proportion of the crude oil
sludge (A) to the sum of the crude oil sludge (A) and the
crude oil (B) is 20 to 95% by mass, preferably 40 to 90% by
mass, and more preferably 60 to 90% by mass, the crude oil
sludge (A) may be taken out outside the crude oil tank to
provide a mixture, as it is, of the taken-out crude oil
sludge (A) with the crude oil as a mixture of a crude oil
sludge (A) and a crude oil (B) to be used for the heating
and stirring. Alternatively, by using a small amount of a
crude oil, a crude oil sludge (A) deposited on the bottom
of a crude oil tank may be taken out outside the crude oil
tank to further mix, into a mixture of the taken-out crude
oil sludge (A) with the crude oil, the same crude oil as
the crude oil used for taking out the crude oil sludge (A)
or a crude oil different therefrom to make a predetermined
mixing proportion, that is, bring the proportion of the
crude oil sludge (A) to the sum of the crude oil sludge (A)
CA 02989100 2017-12-11
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and the crude oil (B) to 20 to 95% by mass, preferably 40
to 90% by mass, and more preferably 60 to 90% by mass to
provide the obtained mixture as a mixture of a crude oil
sludge (A) with a crude oil (B) to be used for the heating
and stirring.
[0023]
The first step (1) then heats and stirs the mixture of
the crude oil sludge (A) with the crude oil (B) at 40 to
200 C, preferably 50 to 150 C, and more preferably 60 to
100 C to thereby obtain a heated and stirred material of
the crude oil sludge (A) and the crude oil (B). If the
heating and stirring temperature is lower than the above
range, the recovery of oil from the crude oil sludge (A)
becomes insufficient; and if the temperature exceeds the
above range, a demerit due to a loss of light fractions is
generated. A method for heating and stirring the mixture
of the crude oil sludge (A) with the crude oil (B) is not
especially limited, and examples thereof include a method
in which the mixture of the crude oil sludge (A) with the
crude oil (B) is heated and stirred in a tank where the
crude oil sludge (A) taken out of a crude oil tank is
stored. The heating and stirring time is not especially
limited, and is selected according to the stirring
conditions so as to make a homogeneously mixed state.
[0024]
CA 02989100 2017-12-11
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=
The content of oil in the crude oil sludge (A) is not
especially limited, but is usually 30 to 80% by mass. Then,
the oil in the crude oil sludge (A) is dissolved in the
crude oil (B) in the first step by heating and stirring the
mixture of the crude oil sludge (A) with the crude oil (B)
at 40 to 200 C, preferably 50 to 150 C, and more preferably
60 to 100 C.
[0025]
The second step (1) in the method for recovering oil
in a crude oil sludge according to the first aspect of the
present invention is a step of centrifugally separating the
heated and stirred material of the crude oil sludge (A) and
the crude oil (B) obtained by carrying out the first step
(1), at 40 to 200 C into a light liquid and a heavy
fraction to thereby obtain the light liquid.
[0026]
In the second step (1), the temperature when the
heated and stirred material of the crude oil sludge (A) and
the crude oil (B) is centrifugally separated is 40 to 200 C,
preferably 50 to 150 C, and more preferably 60 to 100 C. If
the centrifugal separation temperature is lower than the
above range, then part of the heated and stirred material
of the crude oil sludge (A) and the crude oil (B) freezes
and the fluidity of the heated and stirred material greatly
decreases during the centrifugal separation, and thus the
c.A029891002017-12-11
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centrifugal separation cannot be carried out; and if the
temperature exceeds the above range, a demerit due to a
loss of light fractions is generated. Further in the
second step (1), the temperature when the heated and
stirred material of the crude oil sludge (A) and the crude
oil (B) are centrifugally separated is preferably made
equal to or higher than the heating and stirring
temperature of the mixture of the crude oil sludge (A) with
the crude oil (B) in the first step (1).
[0027]
The heated and stirred material of the crude oil
sludge (A) and the crude oil (B) obtained by carrying out
the first step (1) is a mixture of a light liquid having a
low specific gravity and a heavy fraction having a higher
specific gravity than the light liquid; and in the second
step (1), the light liquid and the heavy fraction are
separated by the difference in specific gravity. Then, the
light liquid is a liquid obtained by that the oil in the
crude oil sludge (A) is dissolved in the crude oil (B) in
the first step (1). That is, the light liquid is basically
composed of the crude oil (B) and the oil in the crude oil
sludge (A) dissolved in the crude oil (B). The heavy
fraction is components in the crude oil sludge (A) which
have not been dissolved in the crude oil (B) in the first
step (1), and mainly asphaltene, moisture, iron, sand, oil
CA 02989100 2017-12-11
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being carried in these components and being in a hard-to-
separate state, and the like.
[0028]
A centrifugal separation apparatus to centrifugally
separate the heated and stirred material in the second step
(1) is not especially limited, and suffices if being one
capable of continuously separating the light liquid and the
heavy fraction by the difference in specific gravity with
the above centrifugal separation temperature being held.
Examples thereof include a decanter-type centrifugal
separator, a disc separator-type centrifugal separator, and
a centrifugal separator in a combination of these.
[0029]
The physical properties of the light liquid obtained
by carrying out the second step (1) are not especially
limited; but its density is preferably 0.80 to 0.95 g/cm3,
and more preferably 0.80 to 0.88 g/cm3; its melting point
is preferably 40 to 150 C, more preferably 40 to 110 C, and
still more preferably 40 to 90 C; its freezing point is
preferably 30 to 140 C, more preferably 30 to 100 C, and
still more preferably 30 to 80 C; and its oil content is
60% by mass or higher.
[0030]
The third step (1) in the method for recovering oil in
a crude oil sludge according to the first aspect of the
CA 02989100 2017-111
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present invention is a step of bringing the temperature of
the light liquid obtained by carrying out the second step
(1) to a temperature equal to or higher than the melting
point thereof, and mixing the light liquid having the
temperature equal to or higher than the melting point into
a crude oil (C) in a crude oil transfer pipe. If the
temperature of the light liquid is lower than the melting
point, it becomes difficult to mix the light liquid into
the crude oil (C) in the crude oil transfer pipe.
[0031]
In the third step (1), the crude oil (C) to be mixed
with the light liquid is not especially limited, and may be
a crude oil before being cleared of solid contents,
moisture and the like after crude oil mining, and being
stored in a crude oil tank, may be a crude oil shortly
after being cleared of solid contents, moisture and the
like after crude oil mining, and starting to be stored in a
crude oil tank, and before generating a crude oil sludge,
or may be a supernatant crude oil in a crude oil tank after
a crude oil sludge is generated on the bottom of the crude
oil tank during a certain-period storage of the crude oil
in the crude oil tank. The crude oil (C) may be the same
crude oil as a crude oil as a generation source of the
crude oil sludge (A), may be a crude oil different
CA 089100 2017--11
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therefrom, or may be the same crude oil as the crude oil
(B) or a crude oil different therefrom.
[0032]
The oil in the crude oil sludge (A) is mainly
hydrocarbons having large molecular weights having 40 or
more carbon atoms, and thus if the temperature of the light
liquid becomes too low compared to the temperature when the
heating and stirring is carried out in the first step (1),
the light liquid freezes or the fluidity of the light
liquid remarkably decreases; therefore, in the third step
(1), the temperature of the light liquid is brought to a
temperature equal to or higher than the melting point
thereof and then the light liquid is mixed into the crude
oil (C). The temperature of the light liquid is preferably
equal to or higher than the melting point, and in the range
of 40 to 200 C, more preferably 50 to 150 C, and still more
preferably 60 to 100 C.
[0033]
In the third step (1), with respect to the relation
between the temperatures of the crude oil (C) and the light
liquid when the light liquid is mixed into the crude oil
(C), the temperature of the crude oil (C) is equal to or
higher than that of the light liquid, or the temperature of
the crude oil (C) is lower than that of the light liquid
and the difference between the temperature of the light
CA 02989100 2017-12-11
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liquid and the temperature of the crude oil (C) is 40 C or
lower. In the case where the temperature of the crude oil
(C) is lower than that of the light liquid, with a smaller
difference between the temperature of the light liquid and
the temperature of the crude oil (C), when the light liquid
is mixed into the crude oil (C), the deposition of the oil
of the crude oil sludge (A) in the crude oil (C) is more
suppressed or even if the oil deposits, more of the oil
deposits finely, more unlikely causing a sludge, and thus a
difference between the temperature of the light liquid and
the temperature of the crude oil (C) that is 40 C or lower
has the following effect: the deposition of the oil of the
crude oil sludge (A) in the crude oil (C) is suppressed or
even if the oil deposits, the oil deposits finely, unlikely
causing a sludge. Further in the case where the
temperature of the crude oil (C) is lower than that of the
light liquid, a difference between the temperature of the
light liquid and the temperature of the crude oil (C) that
is preferably 30 C or lower, more preferably 20 C or lower,
and still more preferably 10 C or lower enhances the
following effect: the deposition of the oil of the crude
oil sludge (A) in the crude oil (C) is suppressed or even
if the oil deposits, the oil deposits finely, unlikely
causing a sludge. Further in the case where the
temperature of the crude oil (C) is equal to or higher than
CA 02989100 2017-12-11
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that of the light liquid, when the light liquid is mixed
into the crude oil (C), the deposition of the oil of the
crude oil sludge (A) in the crude oil (C) is suppressed or
even if the oil deposits, the oil deposits finely, unlikely
causing a sludge, and thus a temperature of the crude oil
(C) equal to or higher than that of the light liquid has
the following effect: when the light liquid is mixed into
the crude oil (C), the deposition of the oil of the crude
oil sludge (A) in the crude oil (C) is suppressed or even
if the oil deposits, the oil deposits finely, unlikely
causing a sludge. Further in the case where the
temperature of the crude oil (C) is equal to or higher than
that of the light liquid, the difference between the
temperature of the crude oil (C) and the temperature of the
light liquid is preferably 10 C or lower, and more
preferably 5 C or lower.
[0034]
In the third step (1), the temperature of the crude
oil (C) flowing in a crude oil transfer pipe meets the
above relation between the temperature of the crude oil (C)
and the temperature of the light liquid; however when the
temperature of the crude oil (C) is too high, a demerit due
to a loss of light fractions is generated, and thus the
temperature of the crude oil (C) is preferably 60 C or
lower, and more preferably 50 C or lower.
cA0m9100201711
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[0035]
In the third step (1), by mixing the light liquid into
the crude oil (C) in the crude oil transfer pipe, the light
liquid is mixed into the crude oil (C). The crude oil
transfer pipe is a transfer pipe to transfer the crude oil
(C), and the crude oil (C) flows therein, and thus mixing
of the light liquid in the crude oil (C) into the crude oil
transfer pipe refers to mixing the light liquid into the
crude oil (C) in the state of flowing in the crude oil
transfer pipe. Then, in the third step (1), by mixing the
light liquid into the crude oil (C) in the flowing state,
the depositing oil of the crude oil sludge (A) can be
dispersed in the crude oil (C) quickly before the
depositing oil of the crude oil sludge (A) aggregates in
the crude oil (C), and thus a sludge can be made unlikely
to be generated in the crude oil (C). By contrast, when
the light liquid is added directly to and mixed with a not-
flowing crude oil, for example, a crude oil in a crude oil
tank, the depositing oil of the crude oil sludge (A) in the
crude oil (C) is unlikely to be dispersed in the crude oil
(C), and thus even if the oil of the crude oil sludge (A)
becomes a fine deposit unlikely forming a sludge, a sludge
becomes likely to be generated in the crude oil (C) because
the depositing oil ends in aggregating immediately after
the mixing.
c.A029891002017-12-11
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[0036]
A method of mixing the light liquid into the crude oil
(C) in the crude oil transfer pipe includes mixing by line
mixing, a static mixer, an injection nozzle, a mixing valve
or the like.
[0037]
In the third step (1), the amount of the light liquid
to be mixed into the crude oil (C) is, with respect to 100
parts by volume of the crude oil (C), preferably 45 parts
by volume or smaller, and more preferably 2 to 15 parts by
volume. When the amount of the light liquid to be mixed
into the crude oil (C) is in the above range, a sludge is
unlikely to be generated in the crude oil (C).
[0038]
In the third step (1), the linear velocity of the
crude oil (C) flowing in the crude oil transfer pipe is
preferably 1 cm/sec or higher, more preferably 4 cm/sec or
higher, and still more preferably 6 cm/sec or higher. When
the linear velocity of the crude oil (C) flowing in the
crude oil transfer pipe is in the above range, the
depositing oil of the crude oil sludge (A) in the crude oil
(C) easily becomes dispersed, and thus a sludge becomes
unlikely to be generated in the crude oil (C). Here,
although there is no upper limit value of the linear
velocity of the crude oil (C) flowing in the crude oil
CA 02989100 2017-12-11
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transfer pipe, the usual linear velocity of the crude oil
in the crude oil transfer pipe is 500 cm/sec or lower in
many cases.
[0039]
Then, by carrying out the third step (1), there is
obtained a crude oil (D) in which the light liquid is mixed
into the crude oil (C).
[0040]
The crude oil (D) according to the present invention
is a crude oil obtained by carrying out:
a first step (1) of mixing a crude oil sludge (A) with
a crude oil (B) so that the proportion of the crude oil
sludge (A) to the sum of the crude oil sludge (A) and the
crude oil (B) becomes 20 to 95% by mass, and then heating
and stirring the mixture of the crude oil sludge (A) with
the crude oil (B) at 40 to 200 C to thereby obtain a heated
and stirred material of the crude oil sludge (A) and the
crude oil (B);
a second step (1) of centrifugally separating the
heated and stirred material at 40 to 200 C into a light
liquid and a heavy fraction to thereby obtain the light
liquid; and
a third step (1) of bringing the temperature of the
light liquid to a temperature equal to or higher than the
melting point thereof, and mixing the light liquid having
CA 089100 2017--11
- 24 -
the temperature equal to or higher than the melting point
into a crude oil (C) in a crude oil transfer pipe, wherein
the temperature of the crude oil (C) is equal to or higher
than the temperature of the light liquid, or the
temperature of the crude oil (C) is lower than the
temperature of the light liquid and the difference between
the temperature of the light liquid and the temperature of
the crude oil (C) is 40 C or lower.
[0041]
The crude oil sludge (A), the crude oil (B), the
mixture of the crude oil sludge (A) with the crude oil (B),
the heated and stirred material of the crude oil sludge (A)
and the crude oil (B), the first step (1), the centrifugal
separation, the light liquid, the heavy fraction, the
second step (1), the crude oil (C) and the third step (1)
relevant to the crude oil (D) according to the present
invention are the same as the crude oil sludge (A), the
crude oil (B), the mixture of the crude oil sludge (A) with
the crude oil (B), the heated and stirred material of the
crude oil sludge (A) and the crude oil (B), the first step
(1), the centrifugal separation, the light liquid, the
heavy fraction, the second step (1), the crude oil (C) and
the third step (1) relevant to the method for recovering
oil in a crude oil sludge according to the first aspect of
the present invention.
CA 089100 2017--11
- 25 -
[0042]
A method for recovering oil in a crude oil sludge
according to a second aspect of the present invention is a
method for recovering oil in a crude oil sludge,
comprising:
a first step (2) of heating a crude oil sludge (A) at
40 to 200 C to thereby obtain a heated material of the
crude oil sludge (A);
a second step (2) of centrifugally separating the
heated material at 40 to 200 C into a light liquid and a
heavy fraction to thereby obtain the light liquid; and
a third step (2) of bringing the temperature of the
light liquid to a temperature equal to or higher than the
melting point thereof, and mixing the light liquid having
the temperature equal to or higher than the melting point
into a crude oil (C) in a crude oil transfer pipe, wherein
the temperature of the crude oil (C) is equal to or higher
than the temperature of the light liquid, or the
temperature of the crude oil (C) is lower than the
temperature of the light liquid and the difference between
the temperature of the light liquid and the temperature of
the crude oil (C) is 40 C or lower.
[0043]
The first step (2) in the method for recovering oil in
a crude oil sludge according to the second aspect of the
CA 02989100 2017-12-11
= - 26 -
present invention is a step of heating a crude oil sludge
(A) at 40 to 200 C to thereby obtain a heated material of
the crude oil sludge (A).
[0044]
The crude oil sludge (A) in the first step (2) is the
same as that in the first step (1).
[0045]
The first step (2) heats the crude oil sludge (A) at
40 to 200 C, preferably 50 to 150 C, and more preferably 60
to 100 C to thereby obtain a heated material of the crude
oil sludge (A). If the heating temperature is lower than
the above range, the recovery of oil from the crude oil
sludge (A) becomes insufficient; and if the temperature
exceeds the above range, the heating cost rises and the
economic efficiency is lost. A method of heating the crude
oil sludge (A) is not especially limited, and examples
thereof include a method in which the crude oil sludge (A)
is heated in a tank where the crude oil sludge (A) taken
out of a crude oil tank is stored.
[0046]
The second step (2) in the method for recovering oil
in a crude oil sludge according to the second aspect of the
present invention is a step of centrifugally separating the
heated material of the crude oil sludge (A) obtained by
carrying out the first step (2), at 40 to 200 C into a
CA 02989100 2017-12-11
- 27
light liquid and a heavy fraction to thereby obtain the
light liquid.
[0047]
In the second step (2), the temperature when the
heated material of the crude oil sludge (A) is
centrifugally separated is 40 to 200 C, preferably 50 to
150 C, and more preferably 60 to 100 C. If the centrifugal
separation temperature is lower than the above range, then
part of the heated material of the crude oil sludge (A)
freezes and the fluidity of the heated material greatly
decreases during the centrifugal separation, and thus the
centrifugal separation cannot be carried out; and if the
temperature exceeds the above range, the heating cost rises
and the economic efficiency is lost. Further in the second
step (2), the temperature when the heated material of the
crude oil sludge (A) is centrifugally separated is
preferably made equal to or higher than the heating
temperature of the crude oil sludge (A) in the first step
(2).
[0048]
The heated material of the crude oil sludge (A)
obtained by carrying out the first step (2) is a mixture of
a light liquid having a low specific gravity and a heavy
fraction having a higher specific gravity than the light
liquid; and in the second step (2), the light liquid and
CA 02989100 2017-12-11
- 28 - the heavy fraction are separated by the difference in
specific gravity. Then, the light liquid is oil in the
crude oil sludge (A). That is, the light liquid is
basically composed of oil in the crude oil sludge (A). The
heavy fraction is components in the crude oil sludge (A)
which have higher specific gravities than the oil, mainly
such as asphaltene, moisture, iron, sand, oil being carried
in these components and being in a hard-to-separate state
by the heating in the first step (2).
[0049]
A centrifugal separation apparatus to centrifugally
separate the heated material in the second step (2) is not
especially limited, and suffices if being one capable of
continuously separating the light liquid and the heavy
fraction by the difference in specific gravity with the
above centrifugal separation temperature being held.
Examples thereof include a decanter-type centrifugal
separator, a disc separator-type centrifugal separator, and
a centrifugal separator in a combination of these.
[0050]
The physical properties of the light liquid obtained
by carrying out the second step (2) are not especially
limited; but its density is preferably 0.80 to 0.95 g/cm3,
and more preferably 0.80 to 0.88 g/cm3; its melting point
is preferably 40 to 150 C, more preferably 40 to 110 C, and
CA 02989100 2017-12-11
- 29 -
still more preferably 40 to 90 C; its freezing point is
preferably 30 to 140 C, more preferably 30 to 100 C, and
still more preferably 30 to 80 C; and its oil content is
60% by mass or higher.
[0051]
The third step (2) in the method for recovering oil in
a crude oil sludge according to the second aspect of the
present invention is a step of bringing the temperature of
the light liquid obtained by carrying out the second step
(2) to a temperature equal to or higher than the melting
point thereof, and mixing the light liquid having the
temperature equal to or higher than the melting point into
a crude oil (C) in a crude oil transfer pipe. If the
temperature of the light liquid is lower than the melting
point, it becomes difficult to mix the light liquid into
the crude oil (C) in the crude oil transfer pipe. The
third step (2) is the same as the third step (1), except
that in the third step (2), the light liquid to be mixed
into the crude oil (C) is a light liquid obtained by
carrying out the first step (2) and the second step (2)
whereas in the third step (1), the light liquid to be mixed
into the crude oil (C) is a light liquid obtained by
carrying out the first step (1) and the second step (1).
[0052]
c.A029891002017-12-11
- 30 -
In the third step (2), the crude oil (C) to be mixed
with the light liquid is not especially limited, and may be
a crude oil before being cleared of solid contents,
moisture and the like after crude oil mining, and being
stored in a crude oil tank, may be a crude oil shortly
after being cleared of solid contents, moisture and the
like after crude oil mining, and starting to be stored in a
crude oil tank, and before generating a crude oil sludge,
or may be a supernatant crude oil in a crude oil tank after
a crude oil sludge is generated on the bottom of the crude
oil tank during a certain-period storage of the crude oil
in the crude oil tank. The crude oil (C) may be the same
crude oil as a crude oil as a generation source of the
crude oil sludge (A), or may be a crude oil different
therefrom.
[0053]
The oil in the crude oil sludge (A) is mainly
hydrocarbons having large molecular weights having 40 or
more carbon atoms, and thus if the temperature of the light
liquid becomes too low compared to the temperature when the
heating is carried out in the first step (2), the light
liquid freezes or the fluidity of the light liquid
remarkably decreases; therefore, in the third step (2), the
temperature of the light liquid is brought to a temperature
equal to or higher than the melting point thereof, and then,
CA 02989100 2017-12-11
- 31 -
the light liquid is mixed into the crude oil (C). The
temperature of the light liquid is preferably equal to or
higher than the melting point, and in the range of 40 to
200 C, more preferably 50 to 150 C, and still more
preferably 60 to 100 C.
[0054]
In the third step (2), with respect to the relation
between the temperatures of the crude oil (C) and the light
liquid when the light liquid is mixed into the crude oil
(C), the temperature of the crude oil (C) is equal to or
higher than that of the light liquid, or the temperature of
the crude oil (C) is lower than that of the light liquid
and the difference between the temperature of the light
liquid and the temperature of the crude oil (C) is 40 C or
lower. In the case where the temperature of the crude oil
(C) is lower than that of the light liquid, with a smaller
difference between the temperature of the light liquid and
the temperature of the crude oil (C), when the light liquid
is mixed into the crude oil (C), the deposition of the oil
of the crude oil sludge (A) in the crude oil (C) is more
suppressed or even if the oil deposits, more of the oil
deposits finely, more unlikely causing a sludge, and thus a
difference between the temperature of the light liquid and
the temperature of the crude oil (C) that is 40 C or lower
has the following effect: the deposition of the oil of the
CA 02989100 2017-12-11
- 32 -
=
crude oil sludge (A) in the crude oil (C) is suppressed or
even if the oil deposits, the oil deposits finely, unlikely
causing a sludge. Further in the case where the
temperature of the crude oil (C) is lower than that of the
light liquid, a difference between the temperature of the
light liquid and the temperature of the crude oil (C) that
is preferably 30 C or lower, more preferably 20 C or lower,
and still more preferably 10 C or lower enhances the
following effect: the deposition of the oil of the crude
oil sludge (A) in the crude oil (C) is suppressed or even
if the oil deposits, the oil deposits finely, unlikely
causing a sludge. Further in the case where the
temperature of the crude oil (C) is equal to or higher than
that of the light liquid, when the light liquid is mixed
into the crude oil (C), the deposition of the oil of the
crude oil sludge (A) in the crude oil (C) is suppressed or
even if the oil deposits, the oil deposits finely, unlikely
causing a sludge, and thus a temperature of the crude oil
(C) that is equal to or higher than that of the light
liquid has the following effect: when the light liquid is
mixed into the crude oil (C), the deposition of the oil of
the crude oil sludge (A) in the crude oil (C) is suppressed
or even if the oil deposits, the oil deposits finely,
unlikely causing a sludge. Further in the case where the
temperature of the crude oil (C) is equal to or higher than
CA 02989100 2017-12-11
- 33 -
that of the light liquid, the difference between the
temperature of the crude oil (C) and the temperature of the
light liquid is preferably 10 C or lower, and more
preferably 5 C or lower.
[0055]
In the third step (2), the temperature of the crude
oil (C) flowing in a crude oil transfer pipe meets the
above relation between the temperature of the crude oil (C)
and the temperature of the light liquid; however when the
temperature of the crude oil (C) is too high, a demerit due
to a loss of light fractions is generated, and thus the
temperature of the crude oil (C) is preferably 60 C or
lower, and more preferably 50 C or lower.
[0056]
In the third step (2), by mixing the light liquid in
the crude oil (C) into the crude oil transfer pipe, the
light liquid is mixed into the crude oil (C). That is, the
light liquid is mixed into the crude oil (C) in the state
of flowing in the crude oil transfer pipe. Further in the
third step (2), by mixing the light liquid into the crude
oil (C) in the flowing state, the depositing oil of the
crude oil sludge (A) can be dispersed in the crude oil (C)
quickly before the depositing oil of the crude oil sludge
(A) aggregates in the crude oil (C), and thus a sludge can
be made unlikely to be generated in the crude oil (C). By
cA029891002017-12-11
- 34 -
contrast, when the light liquid is added directly to and
mixed with a not-flowing crude oil, for example, a crude
oil in a crude oil tank, the depositing oil of the crude
oil sludge (A) in the crude oil (C) is unlikely to be
dispersed in the crude oil (C), and thus even if the oil of
the crude oil sludge (A) becomes a fine deposit unlikely
forming a sludge, a sludge becomes likely to be generated
in the crude oil (C) because the depositing oil ends in
aggregating immediately after the mixing.
[0057]
A method of mixing the light liquid into the crude oil
(C) in the crude oil transfer pipe includes mixing by line
mixing, a static mixer, an injection nozzle, a mixing valve
or the like.
[0058]
In the third step (2), the amount of the light liquid
to be mixed into the crude oil (C) is, with respect to 100
parts by volume of the crude oil (C), preferably 45 parts
by volume or smaller, and more preferably 2 to 15 parts by
volume. When the amount of the light liquid to be mixed
into the crude oil (C) is in the above range, a sludge
becomes unlikely to be generated in the crude oil (C).
[0059]
In the third step (2), the linear velocity of the
crude oil (C) flowing in the crude oil transfer pipe is
CA 089100 2017--11
- 35 -
preferably 1 cm/sec or higher, more preferably 4 cm/sec or
higher, and still more preferably 6 cm/sec or higher. When
the linear velocity of the crude oil (C) flowing in the
crude oil transfer pipe is in the above range, the
depositing oil of the crude oil sludge (A) in the crude oil
(C) easily becomes dispersed, and thus a sludge becomes
unlikely to be generated in the crude oil (C). Here,
although there is no upper limit value of the linear
velocity of the crude oil (C) flowing in the crude oil
transfer pipe, the usual linear velocity of the crude oil
in the crude oil transfer pipe is 500 cm/sec or lower in
many cases.
[0060]
Then, by carrying out the third step (2), there is
obtained a crude oil (E) in which the light liquid is mixed
into the crude oil (C).
[0061]
The crude oil (E) according to the present invention
is a crude oil obtained by carrying out:
a first step (2) of heating a crude oil sludge (A) at
40 to 200 C to thereby obtain a heated material of the
crude oil sludge (A);
a second step (2) of centrifugally separating the
heated material at 40 to 200 C into a light liquid and a
heavy fraction to thereby obtain the light liquid; and
CA 089100 2017--11
- 36 -
a third step (2) of bringing the temperature of the
light liquid to a temperature equal to or higher than the
melting point thereof, and mixing the light liquid having
the temperature equal to or higher than the melting point
into a crude oil (C) in a crude oil transfer pipe, wherein
the temperature of the crude oil (C) is equal to or higher
than the temperature of the light liquid, or the
temperature of the crude oil (C) is lower than the
temperature of the light liquid and the difference between
the temperature of the light liquid and the temperature of
the crude oil (C) is 40 C or lower.
[0062]
The crude oil sludge (A), the heated material of the
crude oil sludge (A), the first step (2), the centrifugal
separation, the light liquid, the heavy fraction, the
second step (2) and the third step (2) relevant to the
crude oil (E) according to the present invention are the
same as the crude oil sludge (A), the heated material of
the crude oil sludge (A), the first step (2), the
centrifugal separation, the light liquid, the heavy
fraction, the second step (2) and the third step (2)
relevant to the method for recovering oil in a crude oil
sludge according to the second aspect of the present
invention.
[0063]
c.A029891002017-12-11
- 37 -
The crude oil (D) according to the present invention
is obtained by carrying out the first step (1), the second
step (1) and the third step (1), and thus when the crude
oil (D) is stored in a crude oil tank, a crude oil sludge
is unlikely to be generated. Further the crude oil (E)
according to the present invention is obtained by carrying
out the first step (2), the second step (2) and the third
step (2), when the crude oil (E) is stored in a crude oil
tank, a crude oil sludge is unlikely to be generated.
[0064]
In the method for recovering oil in a crude oil sludge
according to the first aspect of the present invention, oil
can be recovered from in a crude oil sludge (A) by
dissolving oil in the crude oil sludge (A) in a crude oil
(B) and centrifugally separating a light liquid, that is, a
crude oil (B) containing the oil in the crude oil sludge
(A) dissolved therein from a heavy fraction, that is,
components excluding the oil in the crude oil sludge (A),
by carrying out the first step (1) and the second step (1).
Further in the method for recovering oil in a crude oil
sludge according to the second aspect of the present
invention, oil can be recovered from in a crude oil sludge
(A) by centrifugally separating oil in the crude oil sludge
(A) as a light liquid from a heavy fraction, that is,
CA 089100 2017--11
- 38 -
components excluding the oil in the crude oil sludge (A),
by carrying out the first step (2) and the second step (2).
[0065]
Here, the oil in the crude oil sludge (A) cannot be
dissolved in the crude oil (B) at the crude oil storage
temperature (usually 20 to 40 C), and thus when the light
liquid obtained by carrying out the second step (1) or the
second step (2) is returned directly to a crude oil tank,
simultaneously with contacting of the light liquid with the
crude oil in the crude oil tank, the oil in the crude oil
sludge (A) dissolved in the light liquid is deposited as a
large solid and generates a large deposit, which thus again
forms into a sludge.
[0066]
Then, in the method for recovering oil in a crude oil
sludge according to the present invention, by carrying out
the third step (1) or the third step (2), that is, by
bringing the temperature of the light liquid to a
temperature equal to or higher than the melting point
thereof, and mixing the light liquid into the crude oil (C)
whose temperature is equal to or higher than the
temperature of the light liquid, or whose temperature is
lower than the temperature of the light liquid wherein the
temperature difference between the crude oil (C) and the
light liquid is 40 C or lower, the deposition of the oil of
c.A029891002017-12-11
- 39
the crude oil sludge (A) in the crude oil (C) is suppressed
or even if the oil deposits, the oil deposits finely,
making it possible to unlikely cause a sludge; and by
mixing the light liquid into the crude oil (C) in the
flowing state, the oil in the crude oil sludge (A) can be
dispersed in the crude oil (C) before the depositing oil of
the crude oil sludge (A) aggregates in the crude oil (C);
thus, the oil in the crude oil (C) can be made unlikely to
form into a sludge in the crude oil (C).
Examples
[0067]
Hereinafter, the present invention will be described
more specifically by way of Examples, but the present
invention is not limited thereto.
[0068]
<The crude oil sludge (A)>
A crude oil sludge a recovered from a crude oil tank
Analysis values: oil content: 75.1% by mass,
asphaltene content: 10.3% by mass, moisture content: 11.0%
by mass, sediment content: 3.6% by mass
<The crude oil (B)>
A crude oil b having the following analysis values
API: 30.3 , water and sediment content: 0% by volume
<The crude oil (C)>
The above crude oil b was used as the crude oil (C).
CA 02989100 2017-12-11
- 40 -
[0069]
(Examples 1 to 4)
The crude oil sludge a and the crude oil b were added
to a stirring vessel so that the proportion of the crude
oil sludge a to the sum of the both became 70% by mass; and
the mixture was heated and stirred at 80 C.
Then, with the temperature being held at 80 C, the
heated and stirred material was put in a centrifugal
separator set at 80 C, and centrifugally separated under
the conditions of 80 C, 1,000 G and 1 min.
Then, a light liquid was separated by decantation to
thereby obtain the light liquid. The analysis values of
the obtained light liquid are shown in Table 1.
Then, the light liquid heated to 80 C was mixed in a
corresponding proportion indicated in Table 1 into the
crude oil b of 50 C flowing at a corresponding linear
velocity indicated in Table 1 to thereby obtain a mixture
(mixed sample). The mixing method is as shown in FIG. 1.
Then, the obtained mixture was allowed to stand still
at 35 C for 5 days, and there were measured the amount of
deposited sludge, and API and the water and sediment
content of the crude oil cleared of the sludge. The
results are shown in Table 1.
[0070]
<The measuring method of the amount of deposited sludge>
CA 02989100 2017-12-11
- 41 -
100 mL of the sample was put in a 100-mL centrifuging
tube, and allowed to stand still at 35 C for 5 days. Then,
the centrifuging tube was tilted and the supernatant was
thrown away over 15 sec; and the centrifuging tube was then
turned upside down, and allowed to stand still for 30 sec.
Then, the centrifuging tube was restored to its original
position, and allowed to stand still at 80 C for 60 min;
and the amount of sludge remaining in the centrifuging tube
was measured.
[0071]
(Comparative Examples 1 and 2)
A light liquid heated to 80 C was mixed in a
corresponding proportion indicated in Table 1 into the
crude oil b of 30 C flowing at a corresponding linear
velocity indicated in Table 1 to thereby obtain a mixture
(mixed sample). Here, the light liquid was prepared by the
same method as in the Examples.
Then, the obtained mixture was allowed to stand still
at 35 C for 5 days, and there were measured the amount of
deposited sludge, and API and the water and sediment
content of the crude oil cleared of the sludge. The
results are shown in Table 1.
[0072]
(Comparative Example 3)
CA 02989100 2017-12-11
- 42
A light liquid heated to 80 C was added and mixed,
without being stirred, in a proportion indicated in Table 1
to the crude oil b of 30 C allowed to stand still in a
vessel. Here, the light liquid was prepared by the same
method as in the Examples.
Then, the obtained mixture was allowed to stand still
at 35 C for 5 days, and there were measured the amount of
deposited sludge, and API and the water and sediment
content of the crude oil cleared of the sludge. The
results are shown in Table 1.
[0073]
CA 02989100 2017-12-11
- 43 -
..
,
[Table 1]
Example Example Example Example Comparative Comparative Comparative
1 2 3 4 Example 1
Example 2 Example 3
<First Step> ,
Mixing Proportion (% by
mass)
Crude Oil Sludge a 70 70 70 70 70 70 70
Crude Oil b 30 30 30 30 30 30 30
<Second Step>
_
Light Liquid (% by mass) 72.5 72.5 72.5 72.5 72.5
72.5 72.5
Heavy Fraction (% by
27.5 27.5 27.5 27.5 27_5 27.5
27.5
mass)
Melting Point of Light
78.8 78.8 78.8 78.8 78.8 78.8
78.8
Liquid ( C)
Freezing Point of Light
69.1 69.1 69.1 69.1 69.1 69.1
69.1
Liquid ( C)
Density at I5 C of Light
0.869 0.869 0.869 0.869 0.869 0.869
0.869
Liquid (g/mL)
Oil [% by
95 95 95 95 95 95 95
mass]
Asphaltene [%
4.0 4.0 4.0 4.0 4.0 4.0 4.0
Light Liquid by mass]
Composition Sediment [%
<0.1 <0.1 <0.1 <0.1 <0.1 <0.1
<0.1
by mass]
Moisture [%
0.16 0.16 0.16 0.16 0.16 0.16
0.16
by mass]
<Third Step>
Crude Oil b (parts by
100 100 100 100 100 100 100
volume)
Light Liquid (parts by
7.5 7.5 7.5 7.5 7.5 7.5 7.5
volume)
Temperature of Light
80 80 80 80 80 80 80
Liquid ( C)
Temperature of Crude Oil 50
50 50 50 30 30 30
b ( C)
Linear Velocity of Crude
40 32 20 6.0 32 20 -
Oil b (cm/sec)
<Evaluation Results>
Amount of Deposited
0.9 1.1 1.3 1.0 5.0 5.5 12
Sludge (% by volume)
API ( ) 30.7 30.7 30.7 30.6 30.7
30.7 30.4
1
,
Water And Sediment
0.05 0.05 0.05 0.10 0.05 0.05 0
Content (% by mass) ,
' -
1