U.S. patent application number 15/273192 was filed with the patent office on 2017-01-12 for method for producing hydrocarbon oil and system for producing hydrocarbon oil.
This patent application is currently assigned to JAPAN OIL, GAS AND METALS NATIONAL CORPORATION. The applicant listed for this patent is COSMO OIL CO., LTD., INPEX CORPORATION, JAPAN OIL, GAS AND METALS NATIONAL CORPORATION, JAPAN PETROLEUM EXPLORATION CO., LTD., JX NIPPON OIL & ENERGY CORPORATION, NIPPON STEEL & SUMIKIN ENGINEERING CO., LTD.. Invention is credited to Marie IWAMA, Yuichi TANAKA, Kazuhiko TASAKA.
Application Number | 20170009153 15/273192 |
Document ID | / |
Family ID | 45605179 |
Filed Date | 2017-01-12 |
United States Patent
Application |
20170009153 |
Kind Code |
A1 |
TASAKA; Kazuhiko ; et
al. |
January 12, 2017 |
METHOD FOR PRODUCING HYDROCARBON OIL AND SYSTEM FOR PRODUCING
HYDROCARBON OIL
Abstract
Hydrocarbon oil obtained by Fischer-Tropsch (FT) synthesis
reaction using a catalyst within a slurry bed reactor is
fractionated into a distilled oil and a column bottom oil in a
rectifying column, part of the column bottom oil is flowed into a
first transfer line that connects a column bottom of the rectifying
column to a hydrocracker, at least part of the column bottom oil is
flowed into a second transfer line branched from the first transfer
line and connected to the first transfer line downstream of the
branching point, the amount of the catalyst fine powder to be
captured is monitored while the catalyst fine powder in the column
bottom oil that flows in the second transfer line are captured by a
detachable filter provided in the second transfer line, and the
column bottom oil is hydrocracked within the hydrocracker.
Inventors: |
TASAKA; Kazuhiko; (Tokyo,
JP) ; TANAKA; Yuichi; (Tokyo, JP) ; IWAMA;
Marie; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JAPAN OIL, GAS AND METALS NATIONAL CORPORATION
INPEX CORPORATION
JX NIPPON OIL & ENERGY CORPORATION
JAPAN PETROLEUM EXPLORATION CO., LTD.
COSMO OIL CO., LTD.
NIPPON STEEL & SUMIKIN ENGINEERING CO., LTD. |
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo |
|
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
JAPAN OIL, GAS AND METALS NATIONAL
CORPORATION
Tokyo
JP
INPEX CORPORATION
Tokyo
JP
JX NIPPON OIL & ENERGY CORPORATION
Tokyo
JP
JAPAN PETROLEUM EXPLORATION CO., LTD.
Tokyo
JP
COSMO OIL CO., LTD.
Tokyo
JP
NIPPON STEEL & SUMIKIN ENGINEERING CO., LTD.
Tokyo
JP
|
Family ID: |
45605179 |
Appl. No.: |
15/273192 |
Filed: |
September 22, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13817182 |
Feb 15, 2013 |
9493714 |
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|
PCT/JP2011/068476 |
Aug 12, 2011 |
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15273192 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 31/00 20130101;
C10G 2/00 20130101; C10G 65/18 20130101; C10G 2300/1022 20130101;
C10G 67/16 20130101; C10G 2/342 20130101; C10G 2300/208 20130101;
Y02P 30/20 20151101; C10G 47/00 20130101; C10G 3/56 20130101; C10G
67/00 20130101; C10G 67/02 20130101 |
International
Class: |
C10G 67/02 20060101
C10G067/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 19, 2010 |
JP |
2010-184083 |
Claims
1-2. (canceled)
3. A system for producing a hydrocarbon oil, comprising: a
rectifying column for fractionating a hydrocarbon oil obtained by a
Fischer-Tropsch synthesis reaction using a slurry bed reactor, in
which a catalyst is suspended in a liquid hydrocarbon, into at
least one distilled oil and a column bottom oil; a hydrocracker for
hydrocracking the column bottom oil; a first transfer line
connecting a column bottom of the rectifying column to the
hydrocracker; and a second transfer line branched from a branching
point of the first transfer line, provided with a detachable filter
for capturing a catalyst fine powder derived from the catalyst, and
connected to the first transfer line downstream of the branching
point, wherein the first transfer line does not have a filter
between the branching point and the point where the second transfer
line is connected to the first transfer line downstream of the
branching point.
4. The system for producing a hydrocarbon oil according to claim 3,
wherein the first transfer line and the second transfer line
comprise a flow meter.
5. The system for producing a hydrocarbon oil according to claim 3,
wherein the second transfer line comprises a device that measures a
differential pressure before and after the filter provided in the
second transfer line.
6. The system for producing a hydrocarbon oil according to claim 4,
wherein the second transfer line comprises a device that measures a
differential pressure before and after the filter provided in the
second transfer line.
7. The system for producing a hydrocarbon oil according to claim 3,
wherein the first transfer line does not contain a filter for
monitoring an amount of the catalyst fine powder.
8. The system for producing a hydrocarbon oil according to claim 3,
wherein the detachable filter for capturing a catalyst fine powder
derived from the catalyst is at a halfway point of the second
transfer line.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing a
hydrocarbon oil and a system for producing a hydrocarbon oil.
BACKGROUND ART
[0002] Recently, from the viewpoint of reduction in environmental
load, clean and eco-friendly liquid fuels in which the contents of
sulfur and aromatic hydrocarbons are small have been demanded. From
such a viewpoint, as a technique for producing a raw material
hydrocarbon in order to produce a fuel oil base material that
contains no sulfur or aromatic hydrocarbons and is rich in
aliphatic hydrocarbons, particularly, a kerosene and light oil base
material, a method using a Fischer-Tropsch synthesis reaction
(hereinafter, referred to as the "FT synthesis reaction" in some
cases) in which carbon monoxide gas and hydrogen gas are used as
the raw material has been examined.
[0003] Moreover, a technique in which a synthesis gas whose
principal component is carbon monoxide gas and hydrogen gas is
produced by reforming of a gaseous hydrocarbon raw material such as
natural gas, a hydrocarbon oil (hereinafter, referred to as the "FT
synthetic oil" in some cases) is synthesized from the synthesis gas
by the FT synthesis reaction, and further, through an upgrading
step that is a step of hydrogenating and refining the FT synthetic
oil to produce a variety of liquid fuel oil base materials, the
kerosene and light oil base material and naphtha or wax and the
like are produced is known as a GTL (Gas To Liquids) process (see
the following Patent Literature 1, for example).
[0004] As a synthesis reaction system that synthesizes the
hydrocarbon oil by the FT synthesis reaction, for example, a bubble
column type slurry bed FT synthesis reaction system that blows a
synthesis gas into a slurry, in which a solid catalyst
(hereinafter, referred to as the "FT synthesis catalyst" in some
cases) particle having activity to the FT synthesis reaction is
suspended in the hydrocarbon oil, to make the FT synthesis reaction
is disclosed (see the following Patent Literature 2, for
example).
[0005] As a bubble column type slurry bed FT synthesis reaction
system, for example, an external circulating system including a
reactor that accommodates a slurry to make the FT synthesis
reaction, a gas feeder that blows the synthesis gas into a bottom
of the reactor, an outflow pipe that evacuates from the reactor the
slurry containing the hydrocarbon oil obtained by the FT synthesis
reaction within the reactor, a catalyst separator that separates
the slurry evacuated through the outflow pipe into the hydrocarbon
oil and the FT synthesis catalyst particle, and a re-introducing
pipe that re-introduces the FT synthesis catalyst particle and part
of the hydrocarbon oil separated by the catalyst separator into the
reactor is known.
CITATION LIST
Patent Literature
[Patent Literature 1] Japanese Patent Application Laid-Open
Publication No. 2004-323626
[Patent Literature 2] U.S. Patent Application Laid-Open Publication
No. 2007/0014703
SUMMARY OF INVENTION
Technical Problem
[0006] The catalyst separator in the bubble column type slurry bed
FT synthesis reaction system includes a filter whose opening is
approximately 10 .mu.m, for example. The FT synthesis catalyst
particle in the slurry is captured by the filter to be separated
from the hydrocarbon oil.
[0007] However, part of the FT synthesis catalyst particles are
gradually reduced to a fine powder due to friction between the FT
synthesis catalyst particles, friction with an inner wall or the
like of the reactor, or thermal damage caused by the FT synthesis
reaction. The fine powder whose particle size becomes smaller than
the size of the opening of the filter in the catalyst separator
(hereinafter, referred to as the "catalyst fine powder" in some
cases) may unintendedly pass through the filter with the
hydrocarbon oil to flow into a reaction system in the upgrading
step of the FT synthetic oil. The flow of the catalyst fine powder
into the reaction system causes deterioration in the catalyst used
in the reaction system, increase in pressure loss of the reactor,
and further, reduction in quality of liquid fuel base materials and
liquid fuel products. However, it is difficult to provide a filter
having an opening smaller than the particle size of the catalyst
fine powder in a flow path in which the FT synthetic oil obtained
by the FT synthesis reaction flows at a large flow rate, thereby to
capture the catalyst fine powder, because pressure loss in the
filter is large, and the pressure loss is further increased by
capturing of the catalyst fine powder. Further, in the conventional
method, it is difficult to accurately capture the state of the
catalyst fine powder flowing into the upgrading step. Namely,
because mixing of the catalyst fine powder in the FT synthetic oil
is an event in which mixing of a slight amount of the catalyst fine
powder continues for a long time, and the amount of the catalyst
fine powder to be mixed fluctuates over time, it is difficult to
capture the state of mixing quantitatively with high precision by a
method for periodically sampling the FT synthetic oil to determine
the content of the catalyst fine powder. Particularly, it is
difficult to capture the amount of the catalyst fine powder to flow
into the upgrading step as a cumulative amount with respect to a
lapse of time with high reliability. For this reason, it is
difficult to predict the occurrence of problems depending on the
amount of the catalyst fine powder to be accumulated in the
reaction system in the upgrading step, and take a precautionary
measure based on the prediction.
[0008] The present invention has been made in consideration of the
problems above, and an object of the present invention is to
provide a method for producing a hydrocarbon oil and a production
system in which without having a large influence on operation of an
apparatus for producing a hydrocarbon oil, the amount of a catalyst
fine powder to flow into a reaction system in an upgrading step
used in the Fischer-Tropsch synthesis reaction can be
quantitatively monitored with high precision, and the occurrence of
problems in the reaction system in the step can be predicted.
Solution to Problem
[0009] In order to achieve the object above, a method for producing
a hydrocarbon oil according to the present invention comprises: a
step of obtaining a hydrocarbon oil containing a catalyst fine
powder derived from a catalyst by a Fischer-Tropsch synthesis
reaction using a slurry bed reactor in which the catalyst is
suspended in a liquid hydrocarbon; a step of fractionating the
hydrocarbon oil into at least one distilled oil and a column bottom
oil containing the catalyst fine powder using a rectifying column;
a step of flowing at least part of the column bottom oil through a
second transfer line to capture the catalyst fine powder in the
column bottom oil flowing through the second transfer line by a
detachable filter while flowing the remaining column bottom oil
through a first transfer line to transfer the column bottom oil to
a hydrocracker in a transfer device comprising the first transfer
line that connects a column bottom of the rectifying column to the
hydrocracker, and the second transfer line branched from a
branching point of the first transfer line, provided with the
filter halfway, and connected to the first transfer line downstream
of the branching point; a step of monitoring an amount of the
catalyst fine powder captured by the filter; and a step of
hydrocracking the column bottom oil in the hydrocracker.
[0010] By the method for producing a hydrocarbon oil according to
the present invention, without having a large influence on
operation of an apparatus for producing a hydrocarbon oil, the
amount of a catalyst fine powder to flow into a reaction system in
an upgrading step used in the Fischer-Tropsch synthesis reaction
can be quantitatively monitored with high precision, and the
occurrence of problems in the reaction system in the step can be
predicted.
[0011] In the method for producing a hydrocarbon oil according to
the present invention, it is preferable that the ratio F2/F1 of the
mass flow rate F2 of the column bottom oil to be transferred by the
second transfer line to the mass flow rate F1 of the column bottom
oil to be transferred by the first transfer line be 0.01 to
0.2.
[0012] At a ratio F2/F1 of 0.01 to 0.2, the detachable filter
provided halfway of the second transfer line can be small-sized,
and replacement or the like of the filter can easily be performed.
Here, the "mass flow rate F1 of the column bottom oil to be
transferred by the first transfer line" refers to a mass flow rate
of the column bottom oil in the first transfer line between the
branching point of the second transfer line branched from the first
transfer line and a merging point of the second transfer line with
the first transfer line.
[0013] The system for producing a hydrocarbon oil according to the
present invention includes a rectifying column for fractionating a
hydrocarbon oil obtained by a Fischer-Tropsch synthesis reaction
using a slurry bed reactor, in which a catalyst is suspended in a
liquid hydrocarbon, into at least one distilled oil and a column
bottom oil; a hydrocracker for hydrocracking the column bottom oil;
a first transfer line connecting a column bottom of the rectifying
column to the hydrocracker; and a second transfer line branched
from a branching point of the first transfer line, provided with a
detachable filter for capturing a catalyst fine powder derived from
a catalyst halfway, and connected to the first transfer line
downstream of the branching point.
[0014] According to the system for producing a hydrocarbon oil
according to the present invention, the method for producing a
hydrocarbon oil according to the present invention can be
implemented.
[0015] In the system for producing a hydrocarbon oil according to
the present invention, it is preferable that the first transfer
line and the second transfer line include a flow meter.
[0016] The first transfer line and the second transfer line each
include a flow meter; thereby, from the amount of the catalyst fine
powder captured for a predetermined period by the filter provided
in the second transfer line and a cumulative amount of a fluid
flowed for the period through the first transfer line and that
through the second transfer line, the amount of the catalyst fine
powder flowed into the hydrocracker for the period can be
estimated.
[0017] In the system for producing a hydrocarbon oil according to
the present invention, it is also preferable that the second
transfer line include a device that measures a differential
pressure before and after the filter provided in the second
transfer line.
[0018] The second transfer line includes the device that measures a
differential pressure before and after the filter provided in the
second transfer line; thereby, the amount of the catalyst fine
powder captured by the filter can be estimated in the state where
the filter is mounted on the second transfer line.
Advantageous Effects of Invention
[0019] According to the present invention, the method for producing
a hydrocarbon oil and the production system can be provided in
which without having a large influence on operation of an apparatus
for producing a hydrocarbon oil, the amount of the catalyst fine
powder derived from the catalyst used for the Fischer-Tropsch
synthesis reaction to flow into the reaction system in the
upgrading step of the FT synthetic oil can be quantitatively
captured with high precision, and the occurrence of problems in the
reaction system in the step can be predicted.
BRIEF DESCRIPTION OF DRAWINGS
[0020] FIG. 1 is a schematic view of a system for producing a
hydrocarbon oil according to one embodiment of the present
invention.
DESCRIPTION OF EMBODIMENTS
[0021] Hereinafter, with reference to FIG. 1, a method for
producing a hydrocarbon oil using a system for producing a
hydrocarbon oil and a production system according to one embodiment
of the present invention will be described in detail. Same
reference numerals will be given to same or identical
components.
Outline of System for Producing Hydrocarbon Oil
[0022] A system 100 for producing a hydrocarbon oil used in the
present embodiment is a plant facility for performing a GTL process
that converts a hydrocarbon raw material such as natural gas into a
liquid fuel (hydrocarbon oil) base material such as light oil,
kerosene, and naphtha. The system 100 for producing a hydrocarbon
oil according to the present embodiment mainly includes a reformer
(not shown), a bubble column type slurry bed reactor C2, a first
rectifying column C4, first transfer lines L12 and L16, a second
transfer line L14, a filter 2, a hydrocracker C6, an intermediate
fraction hydrorefining apparatus C8, a naphtha fraction
hydrorefining apparatus C10, and a second rectifying column C12.
The line L12 that forms the first transfer line connects the first
rectifying column C4 to a mixing drum D6. The line L16 that forms
the first transfer line connects a mixing drum D2 to the
hydrocracker C6. The "line" means a piping for transferring a
fluid.
Outline of Method for Producing Hydrocarbon Oil
[0023] A method for producing a hydrocarbon oil using the
production system 100 comprises the following steps S1 to S8.
[0024] In Step S1, in the reformer (not shown), natural gas as the
hydrocarbon raw material is reformed to produce a synthesis gas
containing carbon monoxide gas and hydrogen gas.
[0025] In Step S2, in the bubble column type slurry bed reactor C2,
by the FT synthesis reaction using an FT synthesis catalyst, a
hydrocarbon oil (FT synthetic oil) is synthesized from the
synthesis gas obtained in Step S1. In Step S2, a catalyst fine
powder may be produced from part of the FT synthesis catalyst, and
part of the catalyst fine powder may pass through the filter, which
separates the hydrocarbon oil from the FT synthesis catalyst
particles, to be mixed in the FT synthetic oil to be fed to Step.
S3 described below.
[0026] In Step S3, in the first rectifying column C4, the FT
synthetic oil obtained in Step S2 is fractionated into at least one
distilled oil and a column bottom oil containing the catalyst fine
powder. In the present embodiment, by the fractionation, the FT
synthetic oil is separated into a crude naphtha fraction, a crude
intermediate fraction, and a crude wax fraction. Here, the crude
naphtha fraction and crude intermediate fraction are distilled oils
each obtained by condensing a product once vaporized from the FT
synthetic oil in the first rectifying column C4, and evacuating the
products from the column top of the first rectifying column C4 and
the column middle thereof, respectively; the crude wax fraction is
a column bottom oil evacuated as it is a liquid from the column
bottom without vaporization from the FT synthetic oil. The column
bottom oil may contain the catalyst fine powder produced in Step S2
and mixed in the FT synthetic oil. The crude naphtha fraction, the
crude intermediate fraction, and the crude wax fraction each refer
to a fraction obtained by fractionation of the FT synthetic oil and
not subjected to a hydrorefining or hydrocracking treatment.
[0027] The steps subsequent to Step S4 to be described below
comprise the upgrading step of the FT synthetic oil. In Step S4,
the crude wax fraction that is the column bottom oil in the first
rectifying column C4 separated in Step S3 and contains the catalyst
fine powder is transferred from the first rectifying column C4 to
the hydrocracker C6. The crude wax fraction is transferred through
a transfer device including the first transfer lines L12 and L16
that connect the column bottom of the first rectifying column C4 to
the hydrocracker C6, and the second transfer line L14 branched from
the branching point of the first transfer line L12, provided with
the detachable filter 2 halfway, and connected to the first
transfer line L12 downstream of the branching point. In transfer,
at least part of the crude wax fraction flows through the second
transfer line, and the catalyst fine powder contained therein is
captured by the detachable filter 2 provided halfway of the second
transfer line L14. Further, Step S4 comprises the step of
monitoring the amount of the catalyst fine powder to be captured by
the filter 2.
[0028] In Step S5, in the hydrocracker C6, hydrocracking of the
crude wax fraction separated in Step S3 and transferred in Step S4
is performed.
[0029] In Step S6, in the intermediate fraction hydrorefining
apparatus C8, hydrorefining of the crude intermediate fraction is
performed.
[0030] In Step S7, in the naphtha fraction hydrorefining apparatus
C10, hydrorefining of the crude naphtha fraction is performed.
Further, the hydrorefined naphtha fraction is fractionated in a
naphtha stabilizer C14 to recover naphtha (GTL-naphtha) that is a
product of the GTL process.
[0031] In Step S8, a mixture of the hydrocracking product of the
crude wax fraction and the hydrorefined product of the crude
intermediate fraction is fractionated in the second rectifying
column C12. By the fractionation, a light oil (GTL-fight oil) base
material and a kerosene (GTL-kerosene) base material that are
products of the GTL process are recovered.
[0032] Hereinafter, Steps S1 to S8 will be described more in
detail.
[0033] (Step S1)
[0034] In Step S1, first, a sulfur compound contained in natural
gas is removed by a desulfurization apparatus (not shown). Usually,
the desulfurization apparatus includes a hydrogenation
desulfurization reactor filled with a known hydrogenation
desulfurization catalyst and an adsorptive desulfurization
apparatus provided at the rear stage thereof and filled with an
adsorptive material for hydrogen sulfide such as zinc oxide. The
natural gas is fed to the hydrogenation desulfurization reactor
with hydrogen, and the sulfur compound in the natural gas is
converted into hydrogen sulfide. Subsequently, in the adsorptive
desulfurization apparatus, hydrogen sulfide is removed by
adsorption, and the natural gas is desulfurized. By the
desulfurization of the natural gas, poisoning of a reforming
catalyst filled in the reformer, the FT synthesis catalyst used in
Step S2, and the like by the sulfur compound is prevented.
[0035] The desulfurized natural gas is fed to reforming using
carbon dioxide and steam in the reformer to produce a synthesis gas
at a high temperature containing carbon monoxide gas and hydrogen
gas as principal components. The reforming reaction of the natural
gas in Step S1 is represented by reaction equations (1) and (2).
The reforming method is not limited to the steam carbon dioxide gas
reforming method using carbon dioxide and steam; for example, a
steam reforming method, a partial oxidation reforming method (PDX)
using oxygen, an autothermal reforming method (ATR) that is a
combination of the partial oxidation reforming and the steam
reforming method, a carbon dioxide gas reforming method, or the
like can also be used.
CH.sub.4+H.sub.2O->CO+3H.sub.2 (1)
CH.sub.4+CO.sub.2->2CO+2H.sub.2 (2)
[0036] (Step S2)
[0037] In Step S2, the synthesis gas produced in Step S1 is fed to
the bubble column type slurry bed reactor C2, and hydrocarbon is
synthesized from hydrogen gas and carbon monoxide gas in the
synthesis gas.
[0038] The bubble column type slurry bed FT reaction system
including the bubble column type slurry bed reactor C2 mainly
includes the bubble column type slurry bed reactor C2 that
accommodates a slurry containing the FT synthesis catalyst, a gas
feeder that blows the synthesis gas into the bottom of the reactor
(not shown), a line L2 that evacuates the gaseous hydrocarbon
obtained by the FT synthesis reaction and the non-reacted synthesis
gas from the column top of the bubble column type slurry bed
reactor C2, a gas liquid separator D2 that cools the gaseous
hydrocarbon and non-reacted synthesis gas evacuated from the line
L2, and separates the substance fed from the line L2 into gas and
liquid, an outflow pipe L6 that evacuates the slurry containing
hydrocarbon oil from the reactor, a catalyst separator D4 that
separates the slurry evacuated through the outflow pipe L6 into the
hydrocarbon oil and the FT synthesis catalyst particles, and a
re-introducing pipe L10 that re-introduces the FT synthesis
catalyst particles and part of the hydrocarbon oil separated by the
catalyst separator D4 into the reactor C2, for example. Inside of
the bubble column type slurry bed reactor C2, a heat conducting
pipe (not shown) for removing the reaction heat generated by the FT
synthesis reaction, through which cool water is flowed, is
provided.
[0039] As the FT synthesis catalyst used in the bubble column type
slurry bed reactor C2, a known carrier type FT synthesis catalyst
in which an active metal is supported by an inorganic carrier is
used. As the inorganic carrier, porous oxides such as silica,
alumina, titania, magnesia, and zirconia are used; silica or
alumina is preferable, and silica is more preferable. Examples of
the active metal include cobalt, ruthenium, iron, and nickel;
cobalt and/or ruthenium is preferable, and cobalt is more
preferable. The amount of the active metal to be supported is
preferably 3 to 50% by mass, and more preferably 10 to 40% by mass
based on the mass of the carrier. In the case where the amount of
the active metal to be supported is less than 3% by mass, the
activity tends to be insufficient; in the case where the amount of
the active metal to be supported is more than 50% by mass, the
activity tends to be reduced by aggregation of the active metal.
Other than the active metal, other components may be supported in
the FT synthesis catalyst in order to improve the activity or
control the number of carbon atoms of hydrocarbon to be produced
and distribution thereof. Examples of the other component include a
compound containing a metal element such as zirconium, titanium,
hafnium, sodium, lithium, and magnesium. It is preferable that the
average particle size of the FT synthesis catalyst particle be 40
to 150 .mu.m so that the catalyst particles may easily flow within
the slurry bed reactor as a slurry suspended in the liquid
hydrocarbon. It is also preferable that from the viewpoint of the
fluidity as the slurry, the shape of the FT synthesis catalyst
particle be spherical.
[0040] The active metal is supported by a carrier by a known
method. Examples of the compound containing the active metal
element used for supporting can include salts of mineral acid of an
active metal such as nitric acid salts, hydrochloric acid salts,
and sulfuric acid salts; salts of organic acid such as formic acid,
acetic acid, and propionic acid; and complexes such as
acetylacetonate complexes. The supporting method is not
particularly limited, and an impregnation method represented by an
Incipient Wetness method using a solution of a compound containing
an active metal element is preferably used. The carrier by which
the compound containing the active metal element is supported is
dried by a known method, and more preferably fired under an air
atmosphere by a known method. The firing temperature is not
particularly limited, and usually approximately 300 to 600.degree.
C. By firing, the compound containing the active metal element on
the carrier is converted into metal oxide.
[0041] For the FT synthesis catalyst in order to demonstrate high
activity to the FT synthesis reaction, it is necessary that the
active metal atom be converted into a metal by reduction treatment
of the catalyst in which the active metal atom is oxidized. The
reduction treatment is usually performed by contacting the catalyst
with reducing gas under heating. Examples of the reducing gas
include hydrogen gas, gases containing hydrogen gas such as a mixed
gas of hydrogen gas and an inert gas such as nitrogen gas, and
carbon monoxide gas; preferable is hydrogen containing gas, and
more preferable is hydrogen gas. The temperature in the reduction
treatment is not particularly limited, and it is preferable that it
be usually 200 to 550.degree. C. At a reduction temperature less
than 200.degree. C., the active metal atom tends not to be
sufficiently reduced and not to sufficiently demonstrate the
catalyst activity; at a temperature more than 550.degree. C., the
catalyst activity tends to be reduced due to aggregation of the
active metal or the like. The pressure in the reduction treatment
is not particularly limited, and it is preferable that it be
usually 0.1 to 10 MPa. At a pressure less than 0.1 MPa, the active
metal atom tends not to be sufficiently reduced and not to
sufficiently demonstrate the catalyst activity; at a pressure more
than 10 MPa, facility cost tends to be increased for a need to
increase pressure resistance of the apparatus. The time of the
reduction treatment is not particularly limited, and it is
preferable that it be usually 0.5 to 50 hours. At a reduction time
less than 0.5 hours, the active metal atom tends not to be
sufficiently reduced and not to sufficiently demonstrate the
catalyst activity; at a reduction time more than 50 hours, the
catalyst activity tends to be reduced due to aggregation of the
active metal or the like, and the efficiency tends to be reduced.
The facility in which the reduction treatment is performed is not
particularly limited; for example, the reduction treatment may be
performed in the absence of liquid hydrocarbon within the reactor
to perform the FT synthesis reaction. The reduction treatment may
also be performed within a facility connected to the reactor to
perform the FT synthesis reaction, and the catalyst may be
transferred through a piping to the reactor to perform the FT
synthesis without contacting the catalyst with the air.
[0042] On the other hand, in the case where the reduction treatment
is performed in a facility located in a place different from that
of the facility to perform the FT synthesis reaction such as a
catalyst production facility, the catalyst activated by the
reduction treatment is deactivated if the catalyst is contacted
with the air during transportation or the like. In order to prevent
this, the activated catalyst is subjected to a stabilization
treatment to prevent deactivation caused by contact with the air.
Examples of the stabilization treatment include a method for
performing a light oxidation treatment on an activated catalyst to
form an oxidation coating on the surface of an active metal so as
not to further progress oxidation due to contact with the air, or a
method for coating an activated catalyst with hydrocarbon wax or
the like in the absence of the air to block contact with the air.
In the method for forming an oxidation coating, the catalyst can be
fed to the FT synthesis reaction as it is after transportation; in
the method for performing coating with wax or the like, when the
catalyst is suspended in a liquid hydrocarbon to form a slurry, the
wax or the like used for coating is dissolved in liquid
hydrocarbon, and the activity is demonstrated.
[0043] The reaction condition on the FT synthesis reaction in the
bubble column type slurry bed reactor C2 is not limited; for
example, the following reaction condition is selected. Namely, it
is preferable that the reaction temperature be 150 to 300.degree.
C. from the viewpoint of increase in the conversion rate of carbon
monoxide and the number of carbon atoms of hydrocarbon to be
produced. It is preferable that the reaction pressure be 0.5 to 5.0
MPa. It is preferable that a hydrogen/carbon monoxide ratio (molar
ratio) in the raw material gas be 0.5 to 4.0. It is desirable that
the conversion rate of carbon monoxide be not less than 50% from
the viewpoint of the production efficiency of the FT synthetic
oil.
[0044] Inside of the bubble column type slurry bed reactor C2, a
slurry in which the FT synthesis catalyst particles are suspended
in the liquid hydrocarbon (product of the FT synthesis reaction) is
accommodated. The synthesis gas (CO and H.sub.2) obtained in Step
S1 is injected into the slurry within the reactor through a
dispersion plate installed in the bottom of the bubble column type
slurry bed reactor C2. The synthesis gas blown into the slurry
becomes bubbles, which move upward in the slurry to the upper
portion of the bubble column type slurry bed reactor C2. In the
course thereof, the synthesis gas is dissolved in the liquid
hydrocarbon to contact the FT synthesis catalyst particles;
thereby, the FT synthesis reaction progresses to produce
hydrocarbon. The FT synthesis reaction is represented by reaction
equation (3) below, for example.
2nH.sub.2+nCO->(--CH.sub.2--).sub.n+nH.sub.2O (3)
[0045] A gaseous phase exists in the upper portion of the slurry
accommodated in the bubble column type slurry bed reactor C2. The
light hydrocarbon that is produced by the FT synthesis reaction and
gaseous under the condition within the bubble column type slurry
bed reactor C2 and the non-reacted synthesis gas (CO and H.sub.2)
move from the slurry phase to the gaseous phase portion, and are
further evacuated from the top of the bubble column type slurry bed
reactor C2 through the line L2. Then, by the gas liquid separator
D2 including a cooler (not shown) and connected to the line L2, the
evacuated light hydrocarbon and the non-reacted synthesis gas are
separated into the gas content containing the non-reacted synthesis
gas and hydrocarbon gas having C.sub.4 or less as principal
components and a liquid hydrocarbon (light hydrocarbon oil)
liquefied by cooling. Of these, the gas content is recycled to the
bubble column type slurry bed reactor C2, and the non-reacted
synthesis gas contained in the gas content is fed to the FT
synthesis reaction again. On the other hand, the light hydrocarbon
oil is fed through a line L4 and a line L8 to the first rectifying
column C4.
[0046] On the other hand, the hydrocarbon (heavy hydrocarbon oil)
that is produced by the FT synthesis reaction and a liquid under
the condition within the bubble column type slurry bed reactor C2
and the slurry containing the FT synthesis catalyst particles are
fed from the central portion of the bubble column type slurry bed
reactor C2 through the line L6 to the catalyst separator D4. The FT
synthesis catalyst particles in the slurry are captured by the
filter installed within the catalyst separator D4. The heavy
hydrocarbon oil in the slurry passes through the filter to be
separated from the FT synthesis catalyst particles, and is
evacuated from the line L8 to merge with the light hydrocarbon oil
from the line L4. The mixture of the heavy hydrocarbon oil and the
light hydrocarbon oil is heated in a heat exchanger H2 installed
halfway of the line L8, and then fed to the first rectifying column
C4.
[0047] As the product of the FT synthesis reaction, the hydrocarbon
(light hydrocarbon) that is gaseous under the condition within the
bubble column type reactor C2 and the hydrocarbon (heavy
hydrocarbon oil) that is a liquid under the condition within the
bubble column type reactor C2 are obtained. These hydrocarbons are
substantially normal paraffin, and few aromatic hydrocarbon,
naphthene hydrocarbon and isoparaffin are contained. Distribution
of the number of carbon atoms of the light hydrocarbon and heavy
hydrocarbon oil in total widely ranges from C.sub.4 or less as a
gas at normal temperature to approximately C.sub.80, for example,
as a solid (wax) at room temperature. The product of the FT
synthesis reaction also contains olefins and oxygen-containing
compounds containing oxygen atoms derived from carbon monoxide
(e.g., alcohols) as a by-product.
[0048] If the opening of the filter that the catalyst separator D4
includes is smaller than the particle size of the FT synthesis
catalyst particle, the size of the opening is not particularly
limited, preferably 10 to 20 .mu.m, and more preferably 10 to 15
.mu.m. The FT synthesis catalyst particles captured by the filter
that the catalyst separator D4 includes are re-introduced through
the line L10 into the bubble column type reactor C2 by properly
flowing (backwashing) the liquid hydrocarbon in a direction
opposite to the ordinary flow direction, and re-used.
[0049] Part of the FT synthesis catalyst particles that flow as the
slurry in the bubble column type slurry bed reactor C2 wear or
collapse due to friction between the catalyst particles, friction
with the wall of the apparatus or the heat conducting pipe provided
within the reactor for cooling, or damages or the like caused by
the reaction heat to produce the catalyst fine powder. Here, the
particle size of the catalyst fine powder is not particularly
limited, and is a size such that the catalyst fine powder may pass
through the filter that the catalyst separator D4 includes, namely,
the particle size is equal to or smaller than the size of the
opening of the filter. For example, in the case where the opening
of the filter is 10 .mu.m, a catalyst particle having a particle
size of not more than 10 .mu.m is referred to as the catalyst fine
powder. The catalyst fine powder contained in the slurry passes
through the filter with the heavy hydrocarbon oil, and fed to the
first rectifying column C4.
[0050] (Step S3)
[0051] In Step S3, the hydrocarbon oil comprising the mixture of
the light hydrocarbon oil and heavy hydrocarbon oil fed from the
bubble column type slurry bed reactor C2 (FT synthetic oil) is
fractionated in the first rectifying column C4. By the
fractionation, the FT synthetic oil is separated into the crude
naphtha fraction having approximately C.sub.5 to C.sub.10 whose
boiling point is lower than approximately 150.degree. C., the crude
intermediate fraction having approximately C.sub.11 to C.sub.20
whose boiling point is approximately 150 to 360.degree. C., and the
crude wax fraction having approximately C.sub.21 or more whose
boiling point is approximately more than 360.degree. C.
[0052] The crude naphtha fraction is evacuated through a line L20
connected to the column top of the first rectifying column C4. The
crude intermediate fraction is evacuated through a line L18
connected to the central portion of a first rectifying column C4.
The crude wax fraction is evacuated through the line L12 connected
to the bottom of the first rectifying column C4.
[0053] The catalyst fine powder contained in the FT synthetic oil
to be fed to the first rectifying column C4 does not accompany the
distilled oil obtained by vaporization once and subsequent
condensation within the first rectifying column C4 (crude naphtha
fraction and crude intermediate fraction), and substantially
accompanies only the crude wax fraction that is not vaporized
within the first rectifying column C4 but kept in a liquid state to
become the column bottom oil. Accordingly, the catalyst fine powder
contained in the FT synthetic oil (the whole fractions) is to be
condensed in the crude wax fraction.
[0054] (Step S4)
[0055] The line L12 connected to the column bottom of the first
rectifying column C4 is connected to the mixing drum D6, and the
mixing drum D6 and the hydrocracker C6 are connected to each other
through the line L16. The line L12 and line L16 through the mixing
drum D6 form the first transfer line. The line L14 is branched from
the branching point on the line L12, and connected to the line L12
downstream of the branching point through the filter 2 for
capturing the catalyst fine powder contained in the crude wax
fraction. The line L14 and the filter 2 form the second transfer
line.
[0056] It is preferable that the line L12 that forms the first
transfer line (preferably a position downstream of the branching
point from the line L14 and upstream of the merging point with the
line L14) and the line L14 that forms the second transfer line each
be provided with a flow meter, and it is more preferable that the
flow meter be one that can measure a cumulative flow rate.
[0057] The first transfer line and the second transfer line include
the flow meter; thereby, the amount of the catalyst fine powder
flowed into the hydrocracker for a predetermined period can be
estimated from the amount of catalyst fine powder captured by the
filter provided in the second transfer line for the period, and the
cumulative amount of the respective fluids flowed through the first
transfer line and second transfer line for the period, by the
method specifically described later.
[0058] It is preferable that the line L12 that forms the first
transfer line (preferably the position downstream of the branching
point of the line L14 and upstream of the merging point with the
line L14) and the line L14 that forms the second transfer line
(preferably upstream of the filter 2) be provided with a valve (not
shown) for adjusting the respective flow rates of the crude wax
fraction in the first transfer line and the second transfer line or
closing the flow path.
[0059] By provision of the valve, the respective flow rates of the
crude wax fraction in the first transfer line and the second
transfer line can be adjusted, and the ratio of the flow rates in
the first transfer line and the second transfer line can be used as
a predetermined value. In replacement of the filter 2 or the like,
the valve provided in the second transfer line L14 is closed to
stop the flow of the crude wax fraction into the filter 2.
[0060] It is preferable that the production system 100 include a
device that measures the differential pressure before and after the
filter 2 such as a differential pressure gauge. The differential
pressure means pressure loss in the filter 2. A large differential
pressure indicates that openings of the filter 2 are clogged with
the catalyst fine powder. Accordingly, the relationship between the
amount of the catalyst fine powder captured by the filter 2 and the
differential pressure before and after the filter 2 is found in
advance; thereby, in the state where the filter 2 is installed in
the second transfer line L14, the amount of the catalyst fine
powder captured by the filter 2 can be estimated from the
differential pressure. Thereby, without limitation to the point in
time when the amount of the catalyst fine powder is measured with
the filter 2 being dismounted, the amount of the catalyst fine
powder captured by the filter 2 at any point in time can be
estimated, and the cumulative amount of the catalyst fine powder to
flow into the hydrocracker C6 from the start of operation to the
point in time can be estimated. Further, when the differential
pressure reaches the predetermined value, the filter 2 may be
dismounted from the second transfer line L14 to be replaced by a
new filter or a reproduced filter from which the captured catalyst
fine powder is removed. Alternatively, the catalyst fine powder may
be removed from the filter 2, and the filter 2 may be reinstalled
in the second transfer line L14. Thereby, capturing of the catalyst
fine powder by the filter and monitoring can be continued.
[0061] If the opening of the filter 2 is smaller than that of the
filter provided within the catalyst separator D4, the opening of
the filter 2 is not particularly limited, preferably less than 10
.mu.m, and more preferably not more than 7 .mu.m. As the opening of
the filter 2 is smaller, the catalyst fine powder can be captured
more securely, but the differential pressure of the filter 2
becomes larger. In order to secure the flow rate of the crude wax
fraction in the second transfer line L14, the opening of the filter
2 is preferably not less than 1 .mu.m, and may be not less than 5
.mu.m.
[0062] As the filter 2, sintered metal filters such as metallic
mesh sintered filters can be used, for example. The sintered metal
filter is a filter produced by heating a metallic mesh, powder, and
the like to a temperature lower than the melting point of the metal
to bond these. The metallic mesh sintered filter is a filter
obtained by layering a plurality of metallic meshes and sintering
the layered metallic meshes in vacuum at a high temperature;
according to the size of the opening of the metallic mesh and the
number of the layered meshes, the diameter (opening) to be formed
in the metallic mesh sintered filter can be adjusted. Particularly
in the case where the flow rate of the fluid that flows through the
second transfer line is small and a small filter is provided, the
filter 2 may be a filter comprising a porous resin membrane such as
a membrane filter.
[0063] In Step S4, at least part of the crude wax fraction flowed
out of the column bottom of the first rectifying column C4 through
the line L12 is flowed into the second transfer line L14, and the
catalyst fine powder in the crude wax fraction that flows through
the second transfer line L14 is continuously captured by the filter
2. On the other hand, the remaining crude wax fraction is
transferred to the hydrocracker C6 through the path from the first
transfer line, i.e., the line L12 through the mixing drum D6 and
the line L16. The crude wax fraction from which the catalyst fine
powder is captured by the filter 2 merges with the crude wax
fraction that flows through the second transfer line L14 into the
first transfer line L12.
[0064] The catalyst fine powder in crude wax fraction that flows
through the second transfer line is continuously captured by the
filter 2; thereby, the amount of the catalyst fine powder to flow
into the hydrocracker C6 can be reduced. Thereby, deterioration of
the hydrocracking catalyst used in Step S5 (hydrocracking) by the
catalyst fine powder can be prevented or suppressed, and increase
in the differential pressure in the hydrocracker C6 can also be
prevented or suppressed. As a result, the hydrocracker C6 can also
be stably continuously operated for a long time.
[0065] In the present embodiment, the FT synthetic oil in which the
catalyst fine powder is mixed is fractionated in the first
rectifying column C4, the filter is provided one of the two
transfer lines through which the crude wax fraction in which the
catalyst fine powder obtained by the fractionation is condensed
flows, and the catalyst fine powder is captured by the filter
thereby to remove at least part of the catalyst fine powder;
accordingly, the flow rate of the fluid that flows through the
filter is reduced, for example, compared with the case where the
filter is provided in the line L8 that feeds the FT synthetic oil
to the first rectifying column C4, and the catalyst fine powder
mixed in the FT synthetic oil is removed by the filter. If the flow
rate of the fluid that flows through the filter is reduced, the
differential pressure in the filter can be reduced, and operation
of the hydrocarbon oil production system 100 is easier. In
addition, if the flow rate of the fluid that flows through the
filter is reduced, the size of the filter, for example, the area
that the fluid passes through can be reduced, leading to reduction
in facility cost and easier operation such as replacement of the
filter.
[0066] Step S4 further comprises a step of monitoring the amount of
the catalyst fine powder captured by the filter 2. Here,
"monitoring the amount of the catalyst fine powder captured" means
that in the case of replacement of the filter 2 or the like, the
amount of the catalyst fine powder captured by the filter used so
far is measured; or the differential pressure before and after the
filter 2 is measured with the filter being mounted, the correlation
between the differential pressure and the amount of the catalyst
fine powder captured by the filter is found in advance, and the
amount of the catalyst fine powder captured is estimated from the
correlation with the differential pressure.
[0067] Examples of the conventional method for capturing the state
of mixing of the catalyst fine powder in the FT synthetic oil
include a method in which the FT synthetic oil containing the
catalyst fine powder is periodically or properly extracted, and the
amount of the catalyst fine powder contained therein is measured.
However, the amount of the catalyst fine powder to be mixed in the
FT synthetic oil is slight and the amount of mixing fluctuates over
time, while frequency of measurement is limited in the conventional
method; accordingly, it is difficult to capture the cumulative
amount of the catalyst fine powder mixed in the FT synthetic oil
for a predetermined period to be flowed into the upgrading step
with high precision.
[0068] On the other hand, in the method for producing a hydrocarbon
oil according to the present embodiment, the amount of the catalyst
fine powder captured by the filter 2 is monitored; thereby, the
cumulative amount of the catalyst fine powder flowed into the
hydrocracker C6 can be estimated with high precision. In the case
of using the method in which the amount of the catalyst fine powder
captured by the filter 2 is estimated by the differential pressure
of the filter 2, the cumulative amount of the catalyst fine powder
to flow into the hydrocracker C6 at any point in time is
estimated.
[0069] The method for measuring the amount of the catalyst fine
powder captured by the filter 2 dismounted from the second transfer
line for replacement or the like is not limited; for example, a
method is used in which the dismounted filter 2 is washed by a
solvent with a low boiling point in which the wax fraction is
dissolved, thereby to remove the adhering wax fraction; further,
the solvent is removed by heating, reduction of pressure, or the
like, and then the mass of the filter in which only the catalyst
fine powder remains is measured; the mass of the catalyst fine
powder captured is calculated from the difference between the
measured mass and the mass of only the filter measured in advance.
In the case where the filter is formed from a material such as a
metal or ceramic, the wax fraction adhering to the filter may be
removed by burning, and then the mass of the filter on which only
the catalyst fine powder remains may be measured, and the mass of
the catalyst fine powder captured may be calculated from the
difference between the measured mass and the mass of only the
filter measured in advance. Alternatively, in the case where the
filter is a filter formed from a material that can be burned and
causes no burning residue such as an organic polymer, the filter
itself may be burned, and the amount of the catalyst fine powder
may be determined as ash.
[0070] The filter 2 subjected to the measurement of the amount of
the catalyst fine powder captured may be subjected to a
reproduction treatment to remove the captured catalyst fine powder,
and re-used. As the method for removing the captured catalyst fine
powder from the filter 2, a method for scraping the adhering
catalyst fine powder, or a method for flowing a fluid in a
direction opposite to the flow direction in use under pressure
using a predetermined apparatus is used, for example.
[0071] On the other hand, in the method in which the correlation
between the differential pressure before and after the filter 2 and
the amount of the catalyst fine powder captured is found in
advance, and the amount of the catalyst fine powder captured is
estimated from the correlation with the differential pressure, the
data on the amount of the catalyst fine powder captured by the
filter 2 measured by the method and the data on the differential
pressure just before the filter 2 is dismounted are accumulated,
and the correlation therebetween is found. If the correlation is
found, without dismounting the filter 2 to measure the amount of
the catalyst fine powder captured, the amount of the catalyst fine
powder captured by the filter 2 can be estimated from the
differential pressure before and after the filter 2 while the
capturing by the filter is continued. In the case where the flow
rate of the crude wax in the second transfer line in which the
filter 2 is provided fluctuates, it is preferable that the flow
rate be measured in order to correct the influence by fluctuation
of the differential pressure due to the flow rate.
[0072] Hereinafter, in the present embodiment, operation to monitor
the amount of the catalyst fine powder captured by the filter 2
thereby to estimate and monitor the state of the catalyst fine
powder flowing into the hydrocracker C6 will be specifically
described.
[0073] A case is assumed in which the hydrocracking catalyst to be
filled in the hydrocracker C6 is replaced by a new hydrocracking
catalyst or a reproduced hydrocracking catalyst to start operation
of the hydrocarbon oil production system 100. In this case, a new
or reproduced (the captured catalyst fine powder is removed) filter
2 is mounted on the second transfer line L14, and monitoring of the
catalyst fine powder flowing into the upgrading step is started at
the same time of the start of operating the hydrocarbon oil
production system 100. The crude wax fraction is flowed into the
first transfer line L12 and the second transfer line L14 branched
from the first transfer line L12 at respective predetermined flow
rates. The amount of the catalyst fine powder to be captured by the
filter 2 is increased with a lapse of time, and following this, the
differential pressure before and after the filter 2 is increased.
When the differential pressure before and after the filter 2 is
increased to a predetermined value, the valve provided in the
second transfer line L14 is closed to temporarily stop the flow of
the crude wax into the second transfer line L14; the filter 2 is
dismounted, and a new filter is mounted to resume the flow of the
crude wax fraction into the second transfer line L14. The amount of
the catalyst fine powder captured by the filter 2 dismounted at the
time of replacement of the filter is measured by the method above,
and the obtained amount of the catalyst fine powder captured (mass)
is defined as w.sub.1. Then, the amount (mass) of the catalyst fine
powder W.sub.1 estimated to flow into the hydrocracker C6 from the
start of operating the hydrocarbon oil production system 100 to the
time of replacement of the filter 2 is represented by equation A.
The cumulative mass flow rate of the crude wax fraction flowed
through the first transfer line L12 for a period from the start of
operating the hydrocarbon oil production system 100 to replacement
of the filter 2 is defined as Sa.sub.1, and the cumulative mass
flow rate of the crude wax fraction flowed through the second
transfer line L14 is defined as Sb.sub.1.
W.sub.1=w.sub.1.times.(Sa.sub.1/Sb.sub.1) (A)
[0074] After replacement of the filter 2, when the differential
pressure before and after the filter 2 is increased with the time
by capturing the catalyst fine powder to reach the predetermined
value, replacement of the filter 2 and measurement of the amount of
the catalyst fine powder captured are performed by the same
operation as before. Then, wherein the amount (mass) of the
catalyst fine powder captured by the dismounted filter 2 is defined
as w.sub.2, the cumulative mass flow rate of the crude wax fraction
flowed through the first transfer line L12 for a period from the
last replacement of the filter 2 to the replacement this time is
defined as Sa.sub.2, and the cumulative mass flow rate of the crude
wax fraction flowed through the second transfer line L14 is defined
as Sb.sub.2, the amount (mass) of the catalyst fine powder W.sub.2
flowed into the hydrocracker C6 for the period is represented by
equation B.
W.sub.2=w.sub.2.times.(Sa.sub.2/Sb.sub.2) (B)
[0075] Hereinafter, this is repeated, and the amount of the
catalyst fine powder captured by the filter 2 between one
replacement and the next replacement of the filter is integrated;
thereby, the estimated cumulative amount W of the catalyst fine
powder that flows into the hydrocracker C6 for the period from the
start of operating the hydrocarbon oil production system 100 to the
closest time of replacement of the filter can be calculated.
Namely, W is calculated by equation C.
W.dbd.W.sub.1+W.sub.2+ (C)
[0076] The cumulative amount of the catalyst fine powder that flows
into the hydrocracker C6 may also be estimated not only by
measuring the amount of the catalyst fine powder captured by the
filter 2, but also using a method for estimating the captured
amount from the differential pressure of the filter 2.
Alternatively, by a combination of the method for measuring the
amount of the catalyst fine powder and the method for estimating
the captured amount from the differential pressure, the estimated
cumulative amount of the catalyst fine powder that flows into the
hydrocracker C6 at any point in time from the start of operating
the hydrocarbon oil production system 100 can be calculated.
[0077] The ratio F2/F1 of the mass flow rate (F2) of the crude wax
fraction that flows through the second transfer line to the mass
flow rate (F1) of the crude wax fraction that flows through the
first transfer line is not limited; as the F2/F1 is larger, the
ratio of the catalyst fine powder captured and removed by the
filter 2 is larger, and the amount of the catalyst fine powder that
flows into the hydrocracker C6 is reduced. On the other hand, as
the F2/F1 is larger, the differential pressure before and after the
filter 2 and the rate of increasing the differential pressure by
capturing the catalyst fine powder is larger, and the frequency of
replacement of the filter 2 is increased. Moreover, the size of the
filter 2, for example, the area in which the crude wax flows needs
to be increased, facility cost is increased, and replacement
operation of the filter is complicated. Accordingly, it is
preferable that the F2/F1 be determined considering a degree of
mixing of the catalyst fine powder in the FT synthetic oil, the
occurrence of problems caused by the catalyst fine powder flowing
into the hydrocracker C6, complicatedness of replacement operation
of the filter 2, and cost needed therefor.
[0078] In the present embodiment, the F2/F1 may be 0.001 to 0.2. In
the case where the F2/F1 is 0.001 to 0.2, the detachable filter 2
provided halfway of the second transfer line can be smaller, and
facility cost of the filter 2 can be reduced. Moreover, the
complicatedness in replacement of the filter 2 can be reduced, and
replacement of the filter 2 can be performed with a high frequency.
Furthermore, the time needed for replacement of the filter 2 can be
reduced, and the time in which the monitoring of the catalyst fine
powder flowing into the hydrocracker C6 is halted can be reduced.
Moreover, by making the filter 2 smaller, operation to determine
the amount of the catalyst fine powder captured by the filter 2 is
easier. Namely, the operation to wash the crude wax fraction
adhering to the dismounted filter 2 by a solvent or burn that for
removal, the operation to weigh the filter 2, and the like can be
performed in a facility for performing ordinary quality management,
or a facility to perform a chemical test depending on the cases.
Thereby, without a hitch in operation of the system 100 for
producing a hydrocarbon oil, the state of the catalyst fine powder
flowing into the hydrocracker C6 can be highly accurately monitored
at low cost and with simple operation all the time.
[0079] In Step S4, a threshold of the cumulative amount of the
catalyst fine powder to flow into the hydrocracker C6 when the
activity of the hydrocracking catalyst to be filled into the
hydrocracker C6 is remarkably reduced may be found in advance.
Moreover, a threshold of the cumulative amount of the catalyst fine
powder to flow into the hydrocracker C6 when serious increase in
the differential pressure in the hydrocracker C6 occurs may be
found in advance. For example, if the catalyst fine powder is
accumulated within the hydrocracker C6, production of a
carbonaceous substance (coke) using the catalyst fine powder as a
nucleus is promoted; thereby, the activity of the hydrocracking
catalyst may be reduced. Moreover, accumulation of the catalyst
fine powder within the hydrocracker C6 may cause increase in the
differential pressure in the hydrocracker C6. The occurrence of
these problems tends to be remarkable when the cumulative amount of
the catalyst fine powder flowed into the hydrocracker C6 exceeds a
predetermined value. Then, the cumulative amount of the catalyst
fine powder flowed into the hydrocracker C6 when the occurrence of
problems in the hydrocracker C6 is remarkable, which is estimated
from the amount of the catalyst fine powder captured by the filter
2, is found in advance, and the cumulative amount is defined as a
threshold of the occurrence of problems in the hydrocracker C6. The
amount of the catalyst fine powder captured by the filter 2 is
monitored; thereby, at a stage in which the cumulative amount of
the catalyst fine powder flowed into the hydrocracker C6 which is
estimated from the amount of the catalyst fine powder captured is
close to the threshold, measures against reduction in the activity
of the hydrocracking catalyst in the hydrocracker C6 and/or
increase in the differential pressure can be taken in advance.
Namely, in the present embodiment, prediction of the occurrence of
problems attributed to the catalyst fine powder can be performed
and precautionary measures based on the prediction can be
taken.
[0080] Moreover, even before the stage in which the cumulative
amount is close to the threshold, in the case where the amount of
the catalyst fine powder to flow into the hydrocracker C6 is
determined to be large based on the monitoring of the amount of the
catalyst fine powder captured by the filter 2 according to the
present embodiment, the precautionary measures can be taken.
[0081] As the precautionary measures, for example, the ratio F2/F1
of the mass flow rate (F2) of the crude wax fraction that flows
through the second transfer line to the mass flow rate (F1) of the
crude wax fraction that flows through the first transfer line in
the present embodiment may be increased, and the amount of the
catalyst fine powder to be captured and removed by the filter 2 may
be increased.
[0082] Moreover, examples of the precautionary measures include a
method in which a facility is operated to remove the catalyst fine
powder to flow into the hydrocracker C6 or reduce the amount
thereof in the case where in the production system 100, the
facility for performing a step of removing at least part of the
catalyst fine powder contained in the crude wax fraction is
provided separated from that of capturing the catalyst fine powder
by the filter 2 according to the present embodiment. Examples of
the step of removing at least part of the catalyst fine powder
contained in the crude wax fraction, separated from that of
capturing the catalyst fine powder by the filter 2, include a step
of feeding at least part of the crude wax fraction that flows out
from the first rectifying column C4 to a storage tank or the like
to separate and capture the catalyst fine powder by sedimenting, or
a step of centrifuging at least part of the crude wax fraction to
separate and capture the catalyst fine powder. The facility to
perform these steps may be operated at the same time as the start
of operating the production system 100, or the operation may be
started at the stage mentioned above based on the monitoring of the
amount of the catalyst fine powder to be captured by the filter 2
according to the present embodiment.
[0083] In the present embodiment, the line L14 branched from the
branching point on the line L12 and connected through the filter 2
to the line L12 downstream of the branching point is the second
transfer line; a line L14a branched from the branching point on the
line L16 connecting the mixing drum D6 to the hydrocracker C6,
provided with a detachable filter 2a halfway, and connected to the
line L16 downstream of the branching point may be provided, and the
line L14a may be the second transfer line instead of the line L14.
In this case, the catalyst fine powder in the crude wax fraction is
captured by the filter 2a to monitor the amount of the catalyst
fine powder to be captured. The total flow rate of the fluid to
flow through the line L16 and the line L14a is larger than the
total flow rate of the crude wax fraction to flow through the line
L12 and the line L14 because the column bottom oil of the second
rectifying column C12 to be recycled from the second rectifying
column C12 is added to the crude wax fraction from the first
rectifying column C4. Because the differential pressure of the
filter is increased with increase in the flow rate, an embodiment
in which the line L12 is the first transfer line, and the line L14
is the second transfer line is preferable. Moreover, the production
system 100 may include all the line L14, the filter 2, the line
L14a, and the filter 2a.
[0084] (Step S5)
[0085] The crude wax fraction transferred from the first rectifying
column C4 in Step S4, with hydrogen gas fed by a feed line of the
hydrogen gas (not shown) connected to the line L16, is heated to
the temperature needed for hydrocracking of the crude wax fraction
by a heat exchanger H4 installed halfway of the line L16, and then
fed to the hydrocracker C6 to be hydrocracked. The crude wax
fraction not sufficiently hydrocracked in the hydrocracker C6
(hereinafter, referred to as the "uncracked wax fraction" in some
cases) is recovered as the column bottom oil of the second
rectifying column C12 in Step S8, recycled by a line L38 to the
line L12, mixed with the crude wax fraction from the first
rectifying column C4 in the mixing drum D6, and fed to the
hydrocracker C6 again.
[0086] The type of the hydrocracker C6 is not particularly limited,
and a fixed bed flow reactor filled with a hydrocracking catalyst
is preferably used. The reactor may be singular, or a plurality of
reactors may be provided in serial or in parallel. Moreover, the
catalyst bed within the reactor may be singular or plural.
[0087] As the hydrocracking catalyst filled in the hydrocracker C6,
a known hydrocracking catalyst is used, and a catalyst in which a
metal that is an element having hydrogenation activity and belongs
to Group 8 to Group 10 in the periodic table is supported by an
inorganic carrier having a solid acidity is preferably used.
[0088] Examples of the inorganic carrier that forms the
hydrocracking catalyst and has suitable solid acidity include those
comprising zeolites such as ultra stable Y-type (USY) zeolite,
Y-type zeolite, mordenite, and .beta. zeolite, and one or more
inorganic compounds selected from amorphous composite metal oxides
having heat resistance such as silica alumina, silica zirconia, and
alumina boria. Further, as the carrier, compositions comprising USY
zeolite, and one or more amorphous composite metal oxides selected
from silica alumina, alumina boria, and silica zirconia are more
preferable, and compositions comprising USY zeolite and alumina
boria and/or silica alumina are still more preferable.
[0089] USY zeolite is one obtained by ultra-stabilizing Y-type
zeolite by a hydrothermal treatment and/or acid treatment; in
addition to the micro fine porous structure called micro fine pores
that Y-type zeolite originally has and whose pore size is not more
than 2 nm, new fine pores having a pore size in the range of 2 to
10 nm are formed in USY zeolite. The average particle size of USY
zeolite is not particularly limited, preferably not more than 1.0
.mu.m, and more preferably not more than 0.5 .mu.m. Moreover, in
USY zeolite, it is preferable that the molar ratio of
silica/alumina (molar ratio of silica to alumina) be 10 to 200, and
it is more preferable that the molar ratio be 15 to 100, and it is
still more preferable that the molar ratio be 20 to 60.
[0090] Moreover, it is preferable that the carrier contain 0.1 to
80% by mass of crystalline zeolite and 0.1 to 60% by mass of
amorphous composite metal oxide having heat resistance.
[0091] The carrier can be produced as follows: a carrier
composition comprising the inorganic compound having solid acidity
and a binder is molded, and fired. The proportion of the inorganic
compound having solid acidity to be blended is preferably 1 to 70%
by mass, and more preferably 2 to 60% by mass based on the whole
mass of the carrier. Moreover, in the case where the carrier
contains USY zeolite, the proportion of USY zeolite to be blended
is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by
mass based on the whole mass of the carrier. Further, in the case
where the carrier contains USY zeolite and alumina boria, it is
preferable that the proportion of USY zeolite to alumina boria to
be blended (USY zeolite/alumina boria) be 0.03 to 1 in the mass
ratio. Moreover, in the case where the carrier contains USY zeolite
and silica alumina, it is preferable that the proportion of USY
zeolite to silica alumina to be blended (USY zeolite/silica
alumina) be 0.03 to 1 in the mass ratio.
[0092] The binder is not particularly limited; alumina, silica,
titania, magnesia are preferable, and alumina is more preferable.
The amount of the binder to be blended is preferably 20 to 98% by
mass, and more preferably 30 to 96% by mass based on the whole mass
of the carrier.
[0093] The temperature in firing the carrier composition is
preferably in the range of 400 to 550.degree. C., more preferably
in the range of 470 to 530.degree. C., and still more preferably in
the range of 490 to 530.degree. C. Firing at such a temperature can
give sufficient solid acidity and mechanical strength to the
carrier.
[0094] Examples of Groups 8 to 10 metals in the periodic table
supported by the carrier and having hydrogenation activity
specifically include cobalt, nickel, rhodium, palladium, iridium,
and platinum. Among these, metals selected from nickel, palladium,
and platinum are preferably used singly or in combinations of two
or more. These metals can be supported on the carrier mentioned
above by a standard method such as impregnation and ion exchange.
The amount of the metal to be supported is not particularly
limited, and it is preferable that the total amount of the metal be
0.1 to 3.0% by mass based on the mass of the carrier. Here, the
periodic table of the elements refers to the long form of the
periodic table of the elements based on the specification by IUPAC
(the International Union of Pure and Applied Chemistry).
[0095] In the hydrocracker C6, the crude wax fraction and part of
the uncracked wax fraction (hydrocarbons having approximately
C.sub.21 or more) is converted into hydrocarbons having
approximately C.sub.20 or less by hydrocracking; further, part
thereof is converted into naphtha fraction (approximately C.sub.5
to C.sub.10) lighter than the target intermediate fraction
(approximately C.sub.11 to C.sub.20) and further gaseous
hydrocarbons having C.sub.4 or less by excessive cracking. On the
other hand, the crude wax fraction and part of the uncracked wax
fraction are not subjected to sufficiently hydrocracking, and
become the uncracked wax fraction having approximately C.sub.21 or
more. The composition of the hydrocracking product is determined
according to the hydrocracking catalyst to be used and the
hydrocracking reaction condition. Here, the "hydrocracking product"
refers to all hydrocracking products containing the uncracked wax
fraction, unless otherwise specified. If the hydrocracking reaction
condition is tighter than necessary, the content of the uncracked
wax fraction in the hydrocracking product is reduced while the
light content which weight is equal to or lighter than the naphtha
fraction is increased to reduce yield of the target intermediate
fraction. On the other hand, if the hydrocracking reaction
condition is milder than necessary, the uncracked wax fraction is
increased to reduce yield of the intermediate fraction. In the case
where the ratio M2/M1 of the mass M2 of the cracked product whose
boiling point is 25 to 360.degree. C. to the mass M1 of all cracked
products whose boiling point is not less than 25.degree. C. is
defined as a "cracking rate," the reaction condition is selected so
that the cracking ratio M2/M1 may be usually 20 to 90%, preferably
30 to 80%, more preferably 45 to 70%.
[0096] In the hydrocracker C6, in parallel with the hydrocracking
reaction, a hydrogenation isomerization reaction of normal paraffin
that includes the crude wax fraction and uncracked wax fraction or
hydrocracking products thereof progresses to produce isoparaffin.
In the case where the hydrocracking product is used as the fuel oil
base material, isoparaffin to be produced by the hydrogenation
isomerization reaction is a component that makes contribution to
improvement in fluidity at a low temperature, and it is preferable
that the production rate be high. Further, removal of olefins and
oxygen-containing compounds such as alcohols that are by-products
of the FT synthesis reaction contained in the crude wax fraction
also progresses. Namely, the olefins are converted into paraffin
hydrocarbons by hydrogenation, and the oxygen-containing compounds
are converted into paraffin hydrocarbon and water by
hydrodeoxidation.
[0097] The reaction condition in the hydrocracker C6 is not
limited, and the following reaction condition can be selected.
Namely, examples of the reaction temperature include 180 to
400.degree. C.; 200 to 370.degree. C. is preferable, 250 to
350.degree. C. is more preferable, and 280 to 350.degree. C. is
particularly preferable. At a reaction temperature more than
400.degree. C., not only does cracking into the light content tend
to progress to reduce the yield of the intermediate fraction, but
the product tends to be colored to limit use as the fuel oil base
material. On the other hand, at a reaction temperature less than
180.degree. C., not only does the hydrocracking reaction tend not
to sufficiently progress to reduce the yield of the intermediate
fraction, but production of isoparaffin by the hydrogenation
isomerization reaction tends to be suppressed, and the
oxygen-containing compounds such as alcohols tend not to be
sufficiently removed to remain. Examples of the hydrogen partial
pressure include 0.5 to 12 MPa, and 1.0 to 5.0 MPa is preferable.
At a hydrogen partial pressure less than 0.5 MPa, hydrocracking,
hydrogenation isomerization and the like tend not to sufficiently
progress; on the other hand, at a hydrogen partial pressure more
than 12 MPa, high pressure resistance is demanded of the apparatus,
and facility cost tends to be increased. Examples of the liquid
hourly space velocity (LHSV) of the crude wax fraction and
uncracked wax fraction include 0.1 to 10.0 h.sup.-1, and 0.3 to 3.5
h.sup.-1 is preferable. At an LHSV less than 0.1 h.sup.-1,
hydrocracking tends to excessively progress, and productivity tends
to be reduced; on the other hand, at an LHSV more than 10.0
h.sup.-1, hydrocracking, hydrogenation isomerization and the like
tend not to sufficiently progress. Examples of the ratio of
hydrogen/oil include 50 to 1000 NL/L, and 70 to 800 NL/L is
preferable. At a ratio of hydrogen/oil less than 50 NL/L,
hydrocracking, hydrogenation isomerization and the like tend not to
sufficiently progress; on the other hand, at a ratio of
hydrogen/oil more than 1000 NL/L, a large-sized hydrogen feeding
apparatus or the like tends to be needed.
[0098] In this example, the hydrocracking product and non-reacted
hydrogen gas flowed from the hydrocracker C6 are cooled, and
separated into gas and liquid at two stages by a gas liquid
separator D8 and a gas liquid separator D10, the relatively heavy
liquid hydrocarbon containing the uncracked wax fraction is
obtained from the gas liquid separator D8, and the gas content
mainly containing hydrogen gas and gaseous hydrocarbons having
C.sub.4 or less and the relatively light liquid hydrocarbon are
obtained from the gas liquid separator D10. By such two-stage
cooling and gas liquid separation, the occurrence of clogging of
the line accompanied by solidification by rapid cooling of the
uncracked wax fraction contained in the hydrocracking product can
be prevented. The liquid hydrocarbons each obtained in the gas
liquid separator D8 and the gas liquid separator D10 merge with a
line L32 through a line L28 and a line L26, respectively. The gas
content separated in the gas liquid separator D12 and mainly
containing hydrogen gas and gaseous hydrocarbon with C.sub.4 or
less is fed to the intermediate fraction hydrorefining apparatus C8
and the naphtha fraction hydrorefining apparatus C10 through a line
(not shown) connecting the gas liquid separator D10 to the line L18
and the line L20, and hydrogen gas is re-used.
[0099] (Step S6)
[0100] The crude intermediate fraction evacuated from the first
rectifying column C4 through the line L18, with the hydrogen gas
fed by a feed line of the hydrogen gas connected to the line L18
(not shown), is heated to the temperature needed for hydrorefining
of the crude intermediate fraction by a heat exchanger H6 installed
in the line L18, and then fed to the intermediate fraction
hydrorefining apparatus C8 to be hydrorefined.
[0101] The type of the intermediate fraction hydrorefining
apparatus C8 is not particularly limited, and a fixed bed flow
reactor filled with a hydrorefining catalyst is preferably used.
The reactor may be singular, or a plurality of reactors may be
provided in serial or in parallel. Moreover, the catalyst bed
within the reactor may be singular or plural.
[0102] As the hydrorefining catalyst used in the intermediate
fraction hydrorefining apparatus C8, catalysts usually used for
hydrorefining and/or hydrogenation isomerization in petroleum
refining or the like, namely, the catalysts in which a metal having
hydrogenation activity is supported by an inorganic carrier can be
used.
[0103] As the metal having hydrogenation activity that forms the
hydrorefining catalyst, one or more metals selected from the group
consisting of metals in Groups 6, 8, 9, and 10 in the periodic
table of the elements are used. Specific examples of these metals
include noble metals such as platinum, palladium, rhodium,
ruthenium, iridium, and osmium, or cobalt, nickel, molybdenum,
tungsten, and iron; preferable are platinum, palladium, nickel,
cobalt, molybdenum, and tungsten, and more preferable are platinum
and palladium. Moreover, two or more of these metals are also
preferably used in combination; examples of a preferable
combination in this case include platinum-palladium,
cobalt-molybdenum, nickel-molybdenum, nickel-cobalt-molybdenum, and
nickel-tungsten.
[0104] Examples of the inorganic carrier that forms the
hydrorefining catalyst include metal oxides such as alumina,
silica, titania, zirconia, and boria. These metal oxides may be
used alone, or used as a mixture of two or more thereof, or a
composite metal oxide such as silica alumina, silica zirconia,
alumina zirconia, and alumina boria. From the viewpoint of
efficiently progressing hydrogenation isomerization of normal
paraffin at the same time of hydrorefining, it is preferable that
the inorganic carrier be a composite metal oxide having solid
acidity such as silica alumina, silica zirconia, alumina zirconia,
and alumina boria. Moreover, a small amount of zeolite may be
contained in the inorganic carrier. Further, in order to improve
the moldability and mechanical strength of the carrier, a binder
may be blended in the inorganic carrier. Examples of a preferable
binder include alumina, silica, and magnesia.
[0105] In the case where the metal is the noble metal, it is
preferable that the content of the metal having hydrogenation
activity in the hydrorefining catalyst be approximately 0.1 to 3%
by mass as the metal atom based on the mass of the carrier.
Moreover, in the case where the metal is a metal other than the
noble metal, it is preferable that the content be approximately 2
to 50% by mass as metal oxide based on the mass of the carrier. In
the case where the content of the metal having hydrogenation
activity is less than the lower limit value, hydrorefining and
hydrogenation isomerization tend not to sufficiently progress. On
the other hand, in the case where the content of the metal having
hydrogenation activity is more than the upper limit value,
dispersion of the metal having hydrogenation activity tends to be
reduced to reduce the activity of the catalyst, and cost of the
catalyst is increased.
[0106] In the intermediate fraction hydrorefining apparatus C8, the
crude intermediate fraction (normal paraffin with approximately
C.sub.11 to C.sub.20 is a principal component) is hydrorefined. In
the hydrorefining, olefins that are a by-product of the FT
synthesis reaction contained in the crude intermediate fraction are
hydrogenated to be converted into paraffin hydrocarbon. Moreover,
oxygen-containing compounds such as alcohols are converted into
paraffin hydrocarbon and water by hydrodeoxidation. Moreover, in
parallel with hydrorefining, the hydrogenation isomerization
reaction of normal paraffin that forms the crude intermediate
fraction progresses to produce isoparaffin. In the case where the
intermediate fraction is used as the fuel oil base material, the
isoparaffin produced by the hydrogenation isomerization reaction is
a component that makes contribution to improvement in fluidity at a
low temperature, and it is preferable that the production rate be
high.
[0107] The reaction condition in the intermediate fraction
hydrorefining apparatus C8 is not limited, and the following
reaction condition can be selected. Namely, examples of the
reaction temperature include 180 to 400.degree. C., 200 to
370.degree. C. is preferable, 250 to 350.degree. C. is more
preferable, and 280 to 350.degree. C. is particularly preferable.
At a reaction temperature more than 400.degree. C., cracking into
the light content tends to progress to reduce the yield of the
intermediate fraction, and the product tends to be colored to
limited use as fuel oil base material. On the other hand, at a
reaction temperature less than 180.degree. C., oxygen-containing
compounds such as alcohols tend not to sufficiently be removed to
remain, and production of isoparaffin by the hydrogenation
isomerization reaction tends to be suppressed. Examples of the
hydrogen partial pressure include 0.5 to 12 MPa, and 1.0 to 5.0 MPa
is preferable. At a hydrogen partial pressure less than 0.5 MPa,
hydrorefining and hydrogenation isomerization tend not to
sufficiently progress; on the other hand, at a hydrogen partial
pressure more than 12 MPa, high pressure resistance is demanded of
the apparatus, and facility cost tends to be increased. Examples of
the liquid hourly space velocity (LHSV) of the crude intermediate
fraction include 0.1 to 10.0 h.sup.-1, and 0.3 to 3.5 h.sup.-1 is
preferable. At an LHSV less than 0.1 h.sup.-1, cracking into the
light content tends to progress to reduce the yield of the
intermediate fraction, and productivity tends to be reduced; on the
other hand, at an LHSV more than 10.0 h.sup.-1, hydrorefining and
hydrogenation isomerization tend not to sufficiently progress.
Examples of the ratio of hydrogen/oil include 50 to 1000 NL/L, and
70 to 800 NL/L is preferable. At a ratio of hydrogen/oil less than
50 NL/L, hydrorefining and hydrogenation isomerization tend not to
sufficiently progress; on the other hand, at a ratio of
hydrogen/oil more than 1000 NL/L, a large-sized hydrogen feeding
apparatus and the like tend to be needed.
[0108] After the gas content mainly containing the non-reacted
hydrogen gas is separated in the gas liquid separator D12 to which
a line L30 is connected, an outflow oil of the intermediate
fraction hydrorefining apparatus C8 is transferred through the line
L32 to merge with the hydrocracking product of the liquid wax
fraction transferred by the line L26. The gas content separated in
the gas liquid separator D12 and mainly containing hydrogen gas is
fed to the hydrocracker C6, and re-used.
[0109] (Step S7)
[0110] The crude naphtha fraction evacuated from the first
rectifying column C4 by the line L20, with the hydrogen gas fed by
a feed line of the hydrogen gas (not shown) connected to the line
L20, is heated to the temperature needed for hydrorefining of the
crude naphtha fraction by a heat exchanger H8 installed in the line
L20, and fed to the naphtha fraction hydrorefining apparatus C10 to
be hydrorefined.
[0111] The type of the naphtha fraction hydrorefining apparatus C10
is not particularly limited, and a fixed bed flow reactor filled
with a hydrorefining catalyst is preferably used. The reactor may
be singular, or a plurality of reactors may be provided in serial
or in parallel. Moreover, the catalyst bed within the reactor may
be singular or plural.
[0112] The hydrorefining catalyst used for the naphtha fraction
hydrorefining apparatus C10 is not particularly limited, and the
hydrorefining catalyst may be the same hydrorefining catalyst as
that used for hydrorefining of the crude intermediate fraction.
[0113] In the naphtha fraction hydrorefining apparatus C10,
unsaturated hydrocarbon contained in the crude naphtha fraction
(normal paraffin with approximately C.sub.5 to C.sub.10 is a
principal component.) is converted into paraffin hydrocarbon by
hydrogenation. Moreover, the oxygen-containing compounds contained
in the crude naphtha fraction such as alcohols are converted into
paraffin hydrocarbon and water by hydrodeoxidation. In the naphtha
fraction, the hydrogenation isomerization reaction does not
progress much because the number of carbon atoms is small.
[0114] The reaction condition in the naphtha fraction hydrorefining
apparatus C10 is not limited, and the same reaction condition as
that in the intermediate fraction hydrorefining apparatus C8 can be
selected.
[0115] The outflow oil of the naphtha fraction hydrorefining
apparatus C10 is fed through a line L34 to a gas liquid separator
D14; in the gas liquid separator D14, the outflow oil is separated
into the gas content in which hydrogen gas is a principal
component, and liquid hydrocarbon. The separated gas content is fed
to the hydrocracker C6, and hydrogen gas contained in this is
re-used. On the other hand, the separated liquid hydrocarbon is
transferred through a line L36 to the naphtha stabilizer C14.
Moreover, part of the liquid hydrocarbon is recycled through a line
L48 to the line L20 upstream of the naphtha fraction hydrorefining
apparatus C10. Because the amount of heat to be produced in
hydrorefining of the crude naphtha fraction (hydrogenation of
olefins and hydrodeoxidation of alcohols and the like) is large,
part of the liquid hydrocarbon is recycled to the naphtha fraction
hydrorefinig apparatus C10 and the crude naphtha fraction is
diluted; thereby, increase in the temperature in the naphtha
fraction hydrorefining apparatus C10 is suppressed.
[0116] In the naphtha stabilizer C14, the liquid hydrocarbon fed
from the naphtha fraction hydrorefining apparatus C10 and the
second rectifying column C12 is fractionated to obtain refined
naphtha with carbon atoms of C.sub.5 to C.sub.10 as a product. The
refined naphtha is transferred from the column bottom of the
naphtha stabilizer C14 through a line L46 to a naphtha tank T6, and
stored. On the other hand, from a line L50 connected to the column
top of the naphtha stabilizer C14, hydrocarbon gas in which
hydrocarbon with the number of carbon atoms of a predetermined
number or less (C.sub.4 or less) is a principal component is
discharged. Because the hydrocarbon gas is not a target product,
the hydrocarbon gas is introduced into an external burning facility
(not shown) to be burned, and then discharged into the air.
[0117] (Step S8)
[0118] The mixed oil comprising the liquid hydrocarbon obtained
from the outflow oil from the hydrocracker C6 and the liquid
hydrocarbon obtained from the outflow oil from the intermediate
fraction hydrorefining apparatus C8 is heated by a heat exchanger
H10 provided in the line L32, and fed to the second rectifying
column C12 to be fractionated into hydrocarbon having approximately
C.sub.10 or less, a kerosene fraction, a light oil fraction, and a
uncracked wax fraction. In the hydrocarbon having approximately
C.sub.10 or less, the boiling point is lower than approximately
150.degree. C.; the hydrocarbon is evacuated from the column top of
the second rectifying column C12 by a line L44. In the kerosene
fraction, the boiling point is approximately 150 to 250.degree. C.;
the kerosene fraction is evacuated from the central portion of the
second rectifying column C12 by a line L42 to be stored in a tank
T4. In the light oil fraction, the boiling point is approximately
250 to 360.degree. C.; the light oil fraction is evacuated from a
lower portion of the second rectifying column C12 by a line L40 to
be stored in a tank T2. In the uncracked wax fraction, the boiling
point exceeds approximately 360.degree. C.; the uncracked wax
fraction is evacuated from the column bottom of the second
rectifying column C12 to be recycled by the line L38 to the line
L12 upstream of the hydrocracker C6. The hydrocarbon having
approximately C.sub.10 or less evacuated from the column top of the
second rectifying column C12 is fed by the lines L44 and L36 to the
naphtha stabilizer, and fractionated with the liquid hydrocarbon
fed from the naphtha fraction hydrorefining apparatus C10.
[0119] As above, the suitable embodiment of the method for
producing a hydrocarbon oil and production system according to the
present invention has been described, but the present invention
will not be always limited to the embodiment described above.
[0120] For example, in the embodiment, as the GTL process, natural
gas is used as the raw material for production of the synthesis
gas, while a non-gaseous hydrocarbon raw material such as asphalt
and a residue oil may be used, for example. Moreover, in the
embodiment, fractionation into three fractions of the crude naphtha
fraction, the crude intermediate fraction, and the crude wax
fraction is performed in the first rectifying column C4, and the
crude naphtha fraction and the crude intermediate fraction are
hydrorefined in individual steps; however, fractionation into two
fractions of a crude light fraction of the crude naphtha fraction
and the crude intermediate fraction in combination and the crude
wax fraction may be performed, and the crude light fraction may be
hydrorefined in one step. Moreover, in the embodiment, the kerosene
fraction and the light oil fraction are fractionated as separate
fractions in the second rectifying column C12; however, these may
be fractionated as one fraction (intermediate fraction).
[0121] Moreover, as described above, the method for producing a
hydrocarbon oil according to the present invention may comprise a
step of capturing catalyst fine powder by the filter 2 and/or the
filter 2a (hereinafter, referred to as a "filter 2 and the like")
and monitoring the amount of the catalyst fine powder to be
captured, and besides this, a step of capturing and removing at
least part of the catalyst fine powder contained in the crude wax
fraction. Moreover, the system for producing a hydrocarbon oil
according to the present invention may include a facility for
capturing and removing at least part of the catalyst fine powder
contained in the crude wax fraction besides that by the filter 2
and the like. Examples of a step of capturing and removing at least
part of the catalyst fine powder contained in the crude wax
fraction besides that by the filter 2 and the like include a step
of separating catalyst fine powder in a storage tank by sedimenting
and capturing the catalyst fine powder, and a step of separating
catalyst fine powder by centrifugation and capturing the catalyst
fine powder. In the case where these steps are provided, from the
viewpoint of capturing the amount of the catalyst fine powder that
remains in the crude wax fraction after the catalyst fine powder is
captured and removed by these step, and flow into the hydrocracker
C6, it is preferable that these steps be performed upstream of the
step of capturing catalyst fine powder by the filter 2 and the like
and monitoring the amount thereof to be captured according to the
present embodiment. Moreover, these steps may be performed all the
time, or performed in the case where the hydrocracking catalyst
filled in the hydrocracker C6 is deteriorated by flow-in of the
catalyst fine powder, or the differential pressure of the
hydrocracker C6 is increased.
INDUSTRIAL APPLICABILITY
[0122] According to the present invention, the method for producing
a hydrocarbon oil and the production system can be provided in
which without having a large influence on operation of an apparatus
for producing a hydrocarbon oil, the amount of the catalyst fine
powder derived from the catalyst used for the Fischer-Tropsch
synthesis reaction to flow into the reaction system in the
upgrading step of the FT synthetic oil can be quantitatively
captured with high precision, and the occurrence of problems in the
reaction system in the step can be predicted.
REFERENCE SIGNS LIST
[0123] 2, 2a . . . Filter, C4 . . . First rectifying column, C6 . .
. Hydrocracker, C8 . . . Intermediate fraction hydrorefining
apparatus, C10 . . . Naphtha fraction hydrorefining apparatus, C12
. . . Second rectifying column, L12, L16 . . . First transfer line,
L14, L14a . . . Second transfer line, 100 . . . System for
producing hydrocarbon oil.
* * * * *