U.S. patent application number 15/122140 was filed with the patent office on 2016-12-22 for ft gtl apparatus and method for producing single synthetic crude oil.
This patent application is currently assigned to DAEWOO SHIPBUILDING & MARINE ENGINEERING CO., LTD.. The applicant listed for this patent is DAEWOO SHIPBUILDING & MARINE ENGINEERING CO., LTD.. Invention is credited to Won Seok KIM, Hyuk KWON, Young Sik MOON.
Application Number | 20160369173 15/122140 |
Document ID | / |
Family ID | 54009262 |
Filed Date | 2016-12-22 |
United States Patent
Application |
20160369173 |
Kind Code |
A1 |
KWON; Hyuk ; et al. |
December 22, 2016 |
FT GTL APPARATUS AND METHOD FOR PRODUCING SINGLE SYNTHETIC CRUDE
OIL
Abstract
Disclosed are a Fischer-Tropsch (FT) gas-to-liquid (GTL)
apparatus for producing unitary synthetic crude oil and an FT GTL
method for producing unitary synthetic crude oil. The FT GTL
apparatus for producing unitary synthetic crude oil of the present
invention is an FT GTL apparatus for producing unitary synthetic
crude oil from floating production, storage, and off-loading
(FPSO), and characterized by comprising: a gas injection
stabilization unit for performing stabilization on the produced
natural gas to generate a natural gas condensate; and a
modification unit for modifying the natural gas, which has been
treated in the gas injection stabilization unit, to produce a
synthetic crude oil product.
Inventors: |
KWON; Hyuk; (Seoul, KR)
; MOON; Young Sik; (Gwangmyeong-si, KR) ; KIM; Won
Seok; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAEWOO SHIPBUILDING & MARINE ENGINEERING CO., LTD. |
Seoul |
|
KR |
|
|
Assignee: |
DAEWOO SHIPBUILDING & MARINE
ENGINEERING CO., LTD.
Seoul
KR
|
Family ID: |
54009262 |
Appl. No.: |
15/122140 |
Filed: |
July 30, 2014 |
PCT Filed: |
July 30, 2014 |
PCT NO: |
PCT/KR2014/007012 |
371 Date: |
August 26, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 5/00 20130101; C10G
2300/1025 20130101; C10G 49/00 20130101; C10G 45/58 20130101; C10G
2/31 20130101; C10G 2/32 20130101; C10G 47/00 20130101; C10G 67/00
20130101; C10G 2300/4037 20130101; C10G 2300/4062 20130101 |
International
Class: |
C10G 5/00 20060101
C10G005/00; C10G 67/00 20060101 C10G067/00; C10G 49/00 20060101
C10G049/00; C10G 2/00 20060101 C10G002/00; C10G 47/00 20060101
C10G047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2014 |
KR |
10-2014-0024695 |
May 19, 2014 |
KR |
10-2014-0059689 |
Claims
1. A Fischer-Tropsch (FT) gas-to-liquid (GTL) apparatus for
producing a single synthetic crude oil in a floating production,
storage, and off-loading (FPSO) unit, comprising: a gas injection
stabilization unit producing a natural gas condensate by
stabilizing produced natural gas; and a reforming unit producing a
synthetic crude oil product by reforming the natural gas treated in
the gas injection stabilization unit.
2. The FT GTL apparatus according to claim 1, further comprising: a
product treatment unit mixing the natural gas condensate with the
synthetic crude oil product to produce a single synthetic crude
oil.
3. The FT GTL apparatus according to claim 2, wherein the gas
injection stabilization unit comprises a first three-phase
separator separating CH.sub.1 to CH.sub.40 and H2O injected in the
separator into CH.sub.1 to CH.sub.4, the natural gas condensate
(CH.sub.5 to CH.sub.40), and water (H2O).
4. The FT GTL apparatus according to claim 3, wherein the synthetic
crude oil product is FT naphtha, FT heavy oil, and FT wax, and the
reforming unit comprises an FT reactor producing the FT wax and a
second three-phase separator producing a first mixture of the FT
naphtha and the FT heavy oil.
5. The FT GTL apparatus according to claim 4, wherein the second
three-phase separator separates syngas treated in the FT reactor
into a tail gas, H.sub.2O, and the first mixture through heat
exchange of the syngas in a first heat exchanger.
6. The FT GTL apparatus according to claim 5, wherein the product
treatment unit comprises: a product mixing tank mixing the first
mixture with a second mixture of the FT naphtha, the FT heavy oil,
and the FT wax and the natural gas condensate; and a storage tank
storing a GTL liquid prepared in the product mixing tank.
7. The FT GTL apparatus according to claim 6, wherein the product
treatment unit further comprises a second heat exchanger performing
heat exchange of the FT wax produced in the FT reactor, a reactor
producing the second mixture by subjecting the FT wax subjected to
heat exchange in the second heat exchanger to hydrocracking or mild
hydroisomerization, and a separator separating unreacted tail gas
from the second mixture.
8. The FT GTL apparatus according to claim 7, wherein the product
treatment unit further comprises a first compressor for compressing
a tail gas and a second compressor for adding hydrogen, and the
unreacted tail gas separated in the separator is supplied to the
second heat exchanger through the first compressor and the second
compressor.
9. The FT GTL apparatus according to claim 2, further comprising: a
tail gas separation unit separating the synthetic crude oil into a
tail gas and a first mixture of FT naphtha and FT heavy oil, and
the first mixture separated in the tail gas separation unit is
supplied to the product treatment unit.
10. The FT GTL apparatus according to claim 1, wherein the
reforming unit comprises: an F-T synthesis unit producing synthetic
oil from syngas produced from the natural gas; and a control unit
controlling the F-T synthesis unit to maintain wax content in the
synthetic crude oil reformed into the synthetic oil at a
predetermined level so as to adjust wax content of the synthetic
crude oil.
11. The FT GTL apparatus according to claim 10, wherein the F-T
synthesis unit is provided with an LT-FT reactor and an HT-FT
reactor in series or in parallel and adjusts flow rates of the
LT-FT reactor and the HT-FT reactor depending upon the composition
of a synthetic crude oil produced at a downstream side of the F-T
synthesis unit.
12. The FT GTL apparatus according to claim 10, wherein the control
unit is provided with a wax detection unit detecting wax content of
the synthetic crude oil and an unreacted gas detection unit
detecting unreacted gas content.
13. The FT GTL apparatus according to claim 12, wherein the control
unit controls the wax content to be maintained at a minimum level
to a degree to which unreacted gas content is maintained within a
predetermined range.
14. A Fischer-Tropsch (FT) gas-to-liquid (GTL) method for producing
a single synthetic crude oil in a floating production, storage, and
off-loading (FPSO) unit, comprising: (a) producing a natural gas
condensate from natural gas; (b) producing FT wax and a first
mixture of FT naphtha and FT heavy oil from syngas; (c) producing a
second mixture of FT naphtha, FT heavy oil, and FT wax; and (d)
producing a single synthetic crude oil by mixing the natural gas
condensate with the first mixture and the second mixture.
15. The FT GTL method according to claim 14, wherein step (c) is
performed though wax hydrocracking or mild hydroisomerization.
16. The FT GTL method according to claim 15, wherein the single
synthetic crude oil produced in step (d) is stored and transported
without heat treatment.
17. The FT GTL method according to claim 15, further comprising:
(e) refining the single synthetic crude oil in an on-shore refinery
plant.
Description
TECHNICAL FIELD
[0001] The present invention relates to an FT (Fischer-Tropsch) GTL
(gas-to-liquid) apparatus and method for producing a single
synthetic crude oil (syncrude) and, more particularly, to an FT GTL
apparatus and method which can fluidize FT wax, which is an
intermediate synthetic crude oil product (FT naphtha, FT heavy oil,
FT wax) produced by chemical processes in a GTL floating
production, storage, and off-loading (FPSO) and is in a solid state
causing difficulty in transportation, by subjecting some of the FT
wax to a low level of general hydrocracking or mild
hydroisomerization and mixing FT naphtha and FT heavy oil with the
FT wax such that the resulting product can be stored and
transported in a solid state.
BACKGROUND ART
[0002] Recently, as petroleum resources are on the brink of being
exhausted, there is demand for alternative resources capable of
producing transportation oils, fuel oils, and petrochemicals.
Representative examples of hydrocarbon materials that can meet such
demand include coal and natural gas, deposits of which are
abundant, and alternative eco-friendly hydrocarbon sources such as
biomass or wastes can be used in order to achieve CO.sub.2
reduction for prevention of global warming. As a method of
producing chemicals such as transportation oils including gasoline
and diesel, alcohols, wax, lube base oils, or olefins from such
alternative hydrocarbon sources, an indirect coal liquefaction
(coal-to-liquid (CTL)) process, a process of producing synthetic
distillates from natural gas (gas-to-liquid (GTL) process), and an
indirect biomass liquefaction (biomass-to-liquid (BTL)) process are
well known in the art.
[0003] An FT GTL process includes converting syngas, in which a
small amount of methane and carbon dioxide are contained and
hydrogen is mixed with carbon monoxide, into large hydrocarbon
molecules using a high pressure catalyst reactor. In other words,
an FT synthesis reaction in a reactor for Fischer-Tropsch synthesis
is as follows:
CO+2H.sub.2.fwdarw.-CH.sub.2+H.sub.2O .DELTA.H(227.degree. C.)=-165
kJ/mol
Methanation reaction
CO+3H.sub.2.fwdarw.CH.sub.4+H.sub.2O .DELTA.H(227.degree. C.)=-215
kJ/mol
water gas shift
CO+H.sub.2O CO.sub.2+H.sub.2.DELTA.H(227.degree. C.)=-40 kJ/mol
Boudouard reaction
2COC+CO.sub.2.DELTA.H(227.degree. C.)=-134 kJ/mol
[0004] Here, as a catalyst, an iron oxide-based catalyst or a
cobalt-based catalyst is used; the reaction temperature ranges from
200.degree. C. to 350.degree. C.; and the reaction pressure ranges
from 10 bar to 30 bar. Such an FT synthesis reaction is a moderate
exothermic reaction, and thermal control through heat exchange,
which is a key determinant in design of the reactor, is important
in order to increase the catalytic reaction rate.
[0005] An FT product produced by the catalyst reactor is composed
of unreacted syngas, methane, ethane, LPG (C3 to C4), naphtha (C5
to C10), heavy oil (C11 to C22), and wax (>C22). Essentially,
several hundreds of components having carbon numbers of 1 to 40 or
more are produced through FT synthesis.
[0006] Relative amount of each of the above components in an
untreated product mainly depends on the reaction temperature of the
reactor and the kind of catalyst used. Generally, there are three
types of basic FT operating systems, that is, high temperature FT
reaction using an iron-based catalyst (HTFT-Fe), low temperature FT
reaction using an iron-based catalyst (LTFT-Fe), and low
temperature FT reaction using a cobalt-based catalyst
(LTFT-Co).
[0007] An FPSO unit is a floating vessel for production, storage,
and offloading of crude oil and serves to produce and store crude
oil and to offload the crude oil onto a crude oil transportation
means such as an oil tanker at sea.
[0008] The FPSO unit includes drilling facilities for off-shore
drilling and an oil/gas separator for separating glassy oil into
crude oil and associated gas. In addition, the FPSO unit includes
storage facilities for storing crude oil and an offloading means
capable of transferring crude oil to a crude oil transportation
means.
[0009] Generally, associated gas incidentally generated in the FPSO
process is burned and discharged to air or is compressed and
reintroduced into an undersea disused oil well. Thus, FPSO-GTL and
FPSO-DME processes using such an associated gas as a raw material
for the GTL process after on-board preparation of syngas are
commonly employed. Further, natural gas extracted directly from a
marginal gas field may be used in an FPSO-GTL process of producing
a synfuel or in an FPSO-LNG process for direct liquefaction.
[0010] Examples of such technology are disclosed in Patent
Documents 1 and 2.
[0011] For example, Patent Document 1 discloses an off-shore
FPSO-DME apparatus for direct synthesis of DME which includes FPSO
equipment including a glassy oil separator and an oil/gas
separation unit, a reforming reactor, a dimethyl ether reactor, an
undersea CO.sub.2 storage device, and a power system for internal
power generation, wherein a hydrogen separator and a carbon dioxide
separation unit are disposed between the reforming reactor and the
dimethyl ether reactor and the carbon dioxide separation unit is
connected to the dimethyl ether reactor such that carbon dioxide
from the carbon dioxide separation unit, and water and carbon
dioxide generated in the power system for internal power generation
are recycled to the reforming reactor and surplus carbon dioxide is
stored undersea.
[0012] Patent Document 2 discloses an off-shore FPSO-GTL apparatus
which includes: FPSO equipment including a glassy oil separator
separating glassy oil extracted from an oil field into an
associated gas and crude oil and an oil/gas separation unit
separating the separated crude oil into oil and gas; a reforming
reactor receiving a gas obtained by removing an H.sub.2S component
from a C.sub.1 to C.sub.4 carbon compound using a desulfurizer,
wherein the carbon compound is separated from the gas supplied from
the FPSO equipment; a liquid-phase carbon compound preparation
device preparing a liquid-phase carbon compound using syngas
passing through the reforming reactor; an upgrading reactor
receiving hydrogen obtained by subjecting syngas passing through
the reforming reactor to a water gas shift reaction; an undersea
CO.sub.2 storage device receiving surplus carbon dioxide obtained
by removing hydrogen from the syngas; and a power system for
internal power generation of the FPSO-GTL apparatus, wherein a
hydrogen separator and a carbon dioxide separation unit are
disposed between the reforming reactor and the liquid-phase carbon
compound preparation apparatus, and a water separator is disposed
between the liquid-phase carbon compound preparation apparatus and
the upgrading reactor, such that water and carbon dioxide from the
water separator and the carbon dioxide separation unit and water
and carbon dioxide generated in the power system for internal power
generation are recycled to the reforming reactor and surplus carbon
dioxide is stored undersea.
[0013] Synthetic crude oil is a fuel artificially prepared using
resources other than petroleum, such as natural gas, coal, or
biomass and is developed as next generation clean fuel technology
by major companies and institutions under the government
administration in Korea. Since demand for a GTL clean fuel is
expected to rapidly increase in the future given increasing oil
prices, such synthetic crude oil technology is considered to be
economically feasible.
[0014] In this context, although development of a GTL FPSO aimed at
allowing technology on land to be realized at sea is proceeding,
there are many problems to solve before commercialization. One of
such problems involved with the GTL FPSO is an issue of securing
flowability for storage and transportation of GTL synthetic crude
oil. This is due to the fact that a synthetic crude oil produced in
the GTL FPSO contains a large amount of wax and thus exhibits high
viscosity. Thus, flowability of the synthetic crude oil is crucial
to secure efficient operation and economic feasibility of the GTL
FPSO.
[0015] For this purpose, there has been proposed a method in which
a synthetic crude oil is heated to a temperature at which the
synthetic crude oil can exhibit flowability based on a concept as
in a typical very large crude oil carrier (VLCC). However, this
method requires additional facilities and fuel supply to
continuously maintain the temperature during a series of processes
including production/storage/offloading/separation.
[0016] As one example of the related art, Korean Patent No.
0,339,993 discloses a fluidization method which includes bringing
tar/sludge into contact with an effective amount of a surfactant
and an effective amount of an inorganic acid and/or a carrier,
wherein the inorganic acid is sulfuric acid, phosphoric acid or a
mixture thereof and is introduced from a container/tube to wash or
fluidize tar/sludge. Thus, this method is expected to remove
tar/sludge such that the resulting product can be easily
transported, handled, and pumped.
[0017] However, this method is aimed at washing tar/sludge without
causing physical deformation of a pipe and a storage tank, and is
thus difficult to use to secure flowability so as to facilitate
transportation and use of a synthetic crude oil produced in the GTL
FPSO.
DISCLOSURE
Technical Problem
[0018] A conventional technique as described above has a problem in
that a refinery apparatus for completely shifting LPG, gasoline,
kerosene, diesel, or the like into a light material through
hydrocracking of wax includes a product fractionating apparatus as
well as a large expensive hydrocracking apparatus, thereby causing
increase in production costs.
[0019] In addition, the conventional technique has a problem in
that three types of products produced by a refinery process are
individually stored and transported, thereby causing increase in
transportation costs.
[0020] The present invention has been conceived to solve such
problems in the art and it is an aspect of the present invention to
provide an FT GTL apparatus and method for producing a single
synthetic crude oil (syncrude) which can produce a single synthetic
crude oil using as few devices as possible.
[0021] It is another aspect of the present invention to provide an
FT GTL apparatus and method for producing a single synthetic crude
oil which can reduce complexity and costs involved with storage of
FPSO products and transportation of the products to an on-shore
refinery.
[0022] It is a further aspect of the present invention to provide
an apparatus for adjusting wax content in a GTL FPSO synthetic
crude oil which allows production and mixing to be achieved with
wax content in a synthetic crude oil produced in a GTL FPSO
adjusted to a predetermined level to secure flowability of the
synthetic crude oil, thereby improving economic feasibility of a
series of processes including production, storage, offloading,
transportation, and separation of the synthetic crude oil.
Technical Solution
[0023] In accordance with one aspect of the present invention, a
Fischer-Tropsch (FT) gas-to-liquid (GTL) apparatus for producing a
single synthetic crude oil in a floating production, storage, and
off-loading (FPSO) unit includes:
[0024] a gas injection stabilization unit producing a natural gas
condensate by stabilizing produced natural gas; and
[0025] a reforming unit producing a synthetic crude oil product by
reforming the natural gas treated in the gas injection
stabilization unit.
[0026] Preferably, the FT GTL apparatus further includes a product
treatment unit mixing the natural gas condensate with the synthetic
crude oil product to produce a single synthetic crude oil.
[0027] Preferably, the gas injection stabilization unit includes a
first three-phase separator separating CH.sub.1 to CH.sub.40 and
H.sub.2O injected in the separator into CH.sub.1 to CH.sub.4, the
natural gas condensate (CH.sub.5 to CH.sub.40), and water
(H.sub.2O).
[0028] Preferably, the synthetic crude oil product is FT naphtha,
FT heavy oil, and FT wax, and the reforming unit includes an FT
reactor producing the FT wax and a second three-phase separator
producing a first mixture of the FT naphtha and the FT heavy
oil.
[0029] Preferably, the second three-phase separator separates
syngas treated in the FT reactor into a tail gas, H.sub.2O, and the
first mixture through heat exchange of the syngas in a first heat
exchanger.
[0030] Preferably, the product treatment unit includes: a product
mixing tank mixing the first mixture with a second mixture of the
FT naphtha, the FT heavy oil, and the FT wax and the natural gas
condensate; and a storage tank storing a GTL liquid prepared in the
product mixing tank.
[0031] Preferably, the product treatment unit further includes a
second heat exchanger performing heat exchange of the FT wax
produced in the FT reactor, a reactor producing the second mixture
by subjecting the FT wax heat exchanged in the second heat
exchanger to hydrocracking or mild hydroisomerization, and a
separator separating unreacted tail gas from the second
mixture.
[0032] Preferably, the product treatment unit further includes a
first compressor for compressing a tail gas and a second compressor
performing hydrogenation, and the unreacted tail gas separated in
the separator is supplied to the second heat exchanger through the
first compressor and the second compressor.
[0033] Preferably, the FT GTL apparatus further includes a tail gas
separation unit separating the synthetic crude oil into a tail gas
and a first mixture of FT naphtha and FT heavy oil, and
[0034] the first mixture separated in the tail gas separation unit
is supplied to the product treatment unit.
[0035] Preferably, the reforming unit includes: an F-T synthesis
unit producing synthetic oil from syngas produced from the natural
gas; and a control unit controlling the F-T synthesis unit to
maintain wax content in the synthetic crude oil reformed into the
synthetic oil at a predetermined level so as to adjust wax content
of the synthetic crude oil.
[0036] Preferably, the F-T synthesis unit is provided with an LT-FT
reactor and an HT-FT reactor in series or in parallel and adjusts
flow rates of the LT-FT reactor and the HT-FT reactor depending
upon the composition of synthetic crude oil produced at a
downstream side of the F-T synthesis unit.
[0037] Preferably, the control unit is provided with a wax
detection unit detecting wax content in the synthetic crude oil and
an unreacted gas detection unit detecting unreacted gas
content.
[0038] Preferably, the control unit controls the wax content to be
maintained at a minimum level to a degree to which unreacted gas
content is maintained within a predetermined range.
[0039] In accordance with another aspect of the present invention,
a Fischer-Tropsch (FT) gas-to-liquid (GTL) method for producing a
single synthetic crude oil in a floating production, storage, and
off-loading (FPSO) unit includes:
[0040] (a) producing a natural gas condensate from natural gas;
[0041] (b) producing FT wax and a first mixture of FT naphtha and
FT heavy oil from syngas;
[0042] (c) producing a second mixture of FT naphtha, FT heavy oil,
and FT wax; and
[0043] (d) producing a single synthetic crude oil by mixing the
natural gas condensate with the first mixture and the second
mixture.
[0044] Preferably, step (c) is performed though hydrocracking or
mild hydroisomerization of wax.
[0045] Preferably, the single synthetic crude oil produced in step
(d) is stored and transported without heat treatment.
[0046] Preferably, the FT GTL method further includes: (e) refining
the single synthetic crude oil in an on-shore refinery plant.
Advantageous Effects
[0047] According to the present invention, it is possible to
provide an FT GTL apparatus and method for producing a single
synthetic crude oil which can save deck space in an FPSO while
reducing production costs due to use of simple product upgrading
equipment, and allows the FPSO to only require one tank to store
products and eliminates a need for additional heat supply needed to
store the products and transfer the products to a pump, thereby
reducing transportation costs.
[0048] In addition, according to the present invention, it is
possible to provide an FT GTL apparatus and method for producing a
single synthetic crude oil which subjects some of FT wax to a low
level of general hydrocracking or mild hydroisomerization after
mixing FT naphtha with FT heavy oil so as to allow a synthetic
crude oil to be transported without being heated, thereby reducing
complexity, space, and cost as compared with the case of using a
refinery apparatus provided with a high pressure hydrocracking
reaction unit while reducing hydrogen consumption as compared with
the case of using such a refinery apparatus.
[0049] Further, according to the present invention, it is possible
to secure flowability of a synthetic crude oil produced in a GTL
FPSO, thereby improving economic feasibility of a series of
processes including production, storage, offloading,
transportation, and separation of the synthetic crude oil, such
that marketable technology can be accumulated in the related
art.
DESCRIPTION OF DRAWINGS
[0050] FIG. 1 is a block diagram of an FT GTL apparatus for
producing a single synthetic crude oil according to a first
embodiment of the present invention.
[0051] FIG. 2 is a block diagram illustrating connection between
the main units of FIG. 1.
[0052] FIG. 3 is a flowchart illustrating an FT GTL method of
producing a single synthetic crude oil according to the first
embodiment of the invention
[0053] FIG. 5 is a view illustrating production, storage,
offloading, transportation, and separation of a single synthetic
crude oil according to the first embodiment of the invention.
[0054] FIG. 6 is a flowchart showing main processes of a GTL FPSO
according to a second embodiment of the present invention.
[0055] FIG. 7 is a block diagram showing main parts of an F-T
synthesis unit of FIG. 6.
[0056] FIG. 8 is a synthetic crude oil weight fraction diagram
illustrating control according to the second embodiment of the
invention.
EMBODIMENTS
[0057] The above and other aspects, features, and advantages of the
present invention will become apparent from the detailed
description of the following embodiments in conjunction with the
accompanying drawings.
[0058] First, the concept of the present invention will be
described.
[0059] A GTL FPSO is an off-shore structure in which a GTL unit is
incorporated into an FPSO (Floating Production, Storage, and
Off-loading) unit so as to produce clean energy at sea. A GTL
process is composed of a reforming process of producing syngas
(H.sub.2, CO) from natural gas (NG), a Fischer-Tropsch (F-T)
process of producing synthetic crude oil from the syngas, and an
upgrading process of converting the synthetic crude oil into a fuel
having a desired carbon number.
[0060] In the GTL FPSO, securing flowability and transferability of
a synthetic crude oil is an issue of growing importance for
commercialization. For this purpose, although installation of
upgrading equipment is considered, there is high probability of
performance and safety problems given the fact that such equipment
has not yet been installed at sea.
[0061] First, in a first embodiment of the present invention, a
single synthetic crude oil product transferable from the FT GTL
FPSO can be produced. In other words, the first embodiment of the
invention provides a novel concept of producing single hybrid FT
synthetic crude oil which is a mixture of FT naphtha, FT heavy oil
and treated FT wax, and can be stored and transferred without heat
treatment.
[0062] The concept of single hybrid FT synthetic crude oil requires
a catalyst, reactor design, and operating system suitable for wax
hydrocracking or mild hydroisomerization. In addition, such a
concept of the single hybrid FT synthetic crude oil can reduce
space and costs for processing FT products while simplifying
storage and transportation requirements for FT GTL FPSO
products.
[0063] Further, synthetic crude oil produced in each of plural FT
GTL FPSOs is transferred to a single on-shore refinery plant and is
treated therein. In addition, the synthetic crude oil may be
produced into a marketable fuel for vehicles through mixing with
general crude oil products and/or through additional refinement.
Such a concept is useful because the concept can operate a carrier
fleet more efficiently and minimize spatial, capital requirements
for the FPSO while allowing a system that can benefit from
economies of scale in an on-shore refinery plant.
[0064] According to the first embodiment of the invention, after FT
naphtha is mixed with FT heavy oil, some of FT wax is subjected to
a low level of general hydrocracking or mild hydroisomerization
such that the synthetic crude oil can be transported without heat
treatment. Such a concept includes transforming mixed synthetic
crude oil such that the synthetic crude oil can be stored and
transported without heat treatment, although the concept includes
using a catalyst and operating system not intended to produce a
final FT product. In addition, this concept also includes using
different catalysts to produce different products without diluting
(or mixing) FT naphtha and FT heavy oil with treated FT wax.
[0065] The above concept includes subjecting FT wax to
hydrocracking or mild hydroisomerization in order to only increase
the pour point and freezing point of the synthetic crude oil
without trying to modify other properties. Thus, it is possible to
reduce costs required for processing an FPSO on-board FT product
while providing size and space reduction and simplifying storage
and transportation of the product.
[0066] Hereinafter, the first embodiment of the invention will be
described with reference to the accompanying drawings.
[0067] FIG. 1 is a block diagram of an FT GTL apparatus for
producing a single synthetic crude oil according to the first
embodiment of the invention.
[0068] Referring to FIG. 1, the FT GTL apparatus for producing a
single synthetic crude oil according to the first embodiment is an
FT GTL apparatus for producing a single synthetic crude oil in an
FPSO, and includes a gas injection stabilization unit 10 receiving
produced gas, a desulfurization unit 20, a natural gas saturation
and pre-reforming unit 30, a small reforming unit 40, a syngas
conditioning unit 50, an FT synthesis unit 60, a tail gas
separation unit 70, and a product treatment unit 80.
[0069] The gas injection stabilization unit 10 performs
stabilization of produced raw natural gas (NG) to produce natural
gas, a natural gas condensate (NG condensate), and water
(H.sub.2O), wherein the natural gas condensate is supplied to the
product treatment unit 80.
[0070] The desulfurization unit 20 removes sulfur from the natural
gas and supplies the raw natural gas to the natural gas saturation
and pre-reforming unit 30. Some of the raw natural gas having been
pre-treated in the natural gas saturation and pre-reforming unit 30
is used as a fuel gas, and the rest of the natural gas is heated by
steam and then supplied to the reforming unit 40 and discharged to
a saturator.
[0071] The reforming unit 40 reforms the steamed natural gas
supplied from the natural gas saturation and pre-reforming unit 30
into raw syngas, thereby producing a synthetic crude oil product.
In addition, a gas untreated in the reforming unit 40 is supplied
to the natural gas saturation and pre-reforming unit 30 as a fuel
gas.
[0072] The raw syngas treated in the reforming unit 40 is produced
into syngas in the syngas conditioning unit 50, and H.sub.2
generated in this process is supplied to the reforming unit 40 and
the product treatment unit 80 as a fuel gas. Further, the syngas
condensate generated in the syngas conditioning unit 50 is supplied
to the natural gas saturation and pre-reforming unit 30 or
discharged.
[0073] The syngas supplied from the syngas conditioning unit 50 is
passed through the FT synthesis unit 60 to be separated into FT wax
and a first mixture of FT naphtha and FT heavy oil, which, in turn,
are supplied to the product treatment unit 80.
[0074] The tail gas separation unit 70 separates the syngas
supplied from the FT synthesis unit 60 into a tail gas and the
first mixture of FT naphtha and FT heavy oil, wherein the first
mixture is supplied to the product treatment unit 80, and the tail
gas is discharged in part or recycled to the natural gas saturation
and pre-reforming unit 30.
[0075] The product treatment unit 80 serves to mix the natural gas
condensate supplied from the gas injection stabilization unit 10
with the first mixture and the FT wax supplied from the FT
synthesis unit 60 and the first mixture supplied from the tail gas
separation unit 70 to produce a single synthetic crude oil
according to the present invention.
[0076] Boiler feed water (BFW) for steam formation is supplied to
the reforming unit 40 and the syngas conditioning unit 50.
[0077] Next, configurations of the gas injection stabilization unit
10, the reforming unit 40, and the product treatment unit 80, which
are main features of the first embodiment of the invention, will be
described with reference to FIG. 2.
[0078] FIG. 2 is a block diagram illustrating connection between
the main units of FIG. 1.
[0079] Referring to FIG. 2, the gas injection stabilization unit 10
includes a first three-phase separator 41 which separates received
CH.sub.1 to CH.sub.40 and H.sub.2O into CH.sub.1 to CH.sub.4, the
natural gas condensate (CH.sub.5 to CH.sub.40) and water
(H.sub.2O). The natural gas condensate (CH.sub.5 to CH.sub.40) is
supplied to the product treatment unit 80, and the water (H.sub.2O)
is supplied to the natural gas saturation and pre-reforming unit
30.
[0080] The reforming unit 40 includes an FT reactor 41 producing FT
wax from the natural gas and a second three-phase separator 42
producing the first mixture of FT naphtha and FT heavy oil. The
second three-phase separator 42 separates the syngas treated in the
FT reactor 41 into a tail gas, H.sub.2O, and the first mixture
through heat exchange in a first heat exchanger 43. The first
mixture is supplied to the product treatment unit 80.
[0081] The product treatment unit 80 includes: a product mixing
tank 81 for mixing the first mixture supplied from the second
three-phase separator 42 with the natural gas condensate supplied
from the gas injection stabilization unit 10 and a second mixture
of FT naphtha, FT heavy oil, and FT wax; a storage tank 82 storing
a GTL liquid prepared in the product mixing tank 81; a second heat
exchanger 83 performing heat exchange of the FT wax produced in the
FT reactor 41; a reactor 84 producing the second mixture through
hydrocracking or mild hydroisomerization of the FT wax subjected to
heat exchange in the second heat exchanger 83; and a separator 85
for separating unreacted tail gas from the second mixture.
[0082] The single synthetic crude oil product according to the
present invention is prepared by mixing FT wax with FT naphtha and
FT heavy oil. As described above, the single synthetic crude oil
product is obtained by mixing the first mixture of FT naphtha and
FT heavy oil with the second mixture of FT naphtha, FT heavy oil,
and FT wax, and the natural gas condensate in the product mixing
tank 81, followed by storage in the storage tank 82.
[0083] The single synthetic crude oil product prepared as above
allows the FPSO to need only one tank to store the product, i.e.
the storage tank 82 and can eliminate a need for additional heat
supply for storage of the product and transfer of the product to a
pump, thereby reducing transportation costs.
[0084] In addition, the product treatment unit 80 further includes
a first compressor 86 which compresses the tail gas separated in
the separator 85 and a second compressor 87 which performs
hydrogenation, wherein unreacted tail gas separated in the
separator 85 is supplied to the second heat exchanger 83 through
the first compressor 86 and the second compressor 87.
[0085] Next, a process of performing production, storage,
offloading, transportation, and separation of the single synthetic
crude oil using the FT GTL apparatus for producing a single
synthetic crude oil as shown in FIGS. 1 and 2 will be described
with reference to FIGS. 3 and 4.
[0086] FIG. 3 is a flowchart illustrating an FT GTL method of
producing a single synthetic crude oil according to the first
embodiment of the invention, and FIG. 4 is a view illustrating
production/storage/offloading/transportation/separation of a single
synthetic crude oil according to the first embodiment of the
invention.
[0087] The FT GTL method of producing a single synthetic crude oil
according to the first embodiment of the invention is an FT GTL
method for producing a single synthetic crude oil in an FPSO, and,
in the method, first, natural gas is subjected to stabilization in
the gas injection stabilization unit 10 to produce a natural gas
condensate (S10).
[0088] Thereafter, sulfur is removed from the natural gas by the
desulfurization unit 20, and a syngas is produced by the natural
gas saturation and pre-reforming unit 30 and the small reforming
unit 40.
[0089] In the reforming unit 40, FT wax and the first mixture of FT
naphtha and FT heavy oil are produced from the syngas (S20).
[0090] Then, in the product treatment unit 80, the FT wax is
subjected to hydrocracking or mild hydroisomerization to produce
the second mixture of FT naphtha, FT heavy oil, and FT wax
(S30).
[0091] In addition, in the product treatment unit 80, the natural
gas condensate produced in step S10 is mixed with the first mixture
produced in step S20 and the second mixture produced in step S30 to
produce a single synthetic crude oil (S40).
[0092] As shown in FIG. 4, the single synthetic crude oil produced
in step S40 is stored and transported without heat treatment (S50).
The single synthetic crude oil transported in step S50 is refined
in an on-shore refinery plant (S60).
[0093] According to the second embodiment of the invention, the FT
synthesis unit 600 is provided to produce synthetic oil from syngas
prepared from natural gas. Referring to FIG. 5, a GTL main process
is performed by the natural gas saturation and pre-reforming unit
300, the reforming unit 400, the syngas conditioning unit 500, the
FT synthesis unit 600, and the product treatment unit 800, which
are sequentially connected to one another. The FT synthesis unit
600 serves to convert the syngas into the synthetic oil, and the
product treatment unit 800 serves to upgrade the synthetic oil to
produce a synthetic crude oil. A surplus syngas generated in the FT
synthesis unit 600 is fractionated in the tail gas separation unit
700 to be partially recycled to the pre-reforming unit 20. The
synthetic crude oil produced in the product treatment unit 800 is
stored in a tank.
[0094] Here, since the synthetic crude oil produced in the GTL FPSO
exhibits high viscosity due to containing a large amount of wax, it
is necessary to secure flowability of the synthetic crude oil so as
to facilitate storage, offloading, and transportation. As the
amount of the wax approaches 100%, the synthetic crude oil is more
likely to be solidified at atmospheric pressure/room temperature,
such that storage and offloading of the synthetic crude oil is
impossible.
[0095] According to the second embodiment, a control unit 900
controls the FT synthesis unit 600 to maintain wax content in the
synthetic crude oil that will be reformed into the synthetic oil at
a predetermined level. The control unit 900 determines the state of
the synthetic crude oil stored in the tank and executes an
algorithm for maintaining the wax content at an optimal level based
on the determination.
[0096] According to details of the second embodiment, the FT
synthesis unit 600 is provided with an LT-FT reactor 620 and an
HT-FT reactor 640 in series or in parallel and adjusts a flow rate
of the LT-FT reactor 620 and the HT-FT reactor 640 depending upon
the composition of a synthetic crude oil produced at a downstream
side thereof. Referring to FIG. 2, the FT synthesis unit 600
includes the HT-FT reactor 640 at a downstream side of the LT-FT
reactor 620. The LT-FT reactor 620 is operated at a temperature of
220.degree. C. to 250.degree. C. and mainly produces a liquid
product such as a heavy oil fraction or wax, and the HT-FT reactor
640 is operated at a temperature of 330.degree. C. to 350.degree.
C. and produces a gaseous product such as gasoline or naphtha.
[0097] When the LT-FT reactor 620 and the HT-FT reactor 640 are
operated at the same time, it is possible to easily secure
flowability of the synthetic crude oil through adjustment of the
amount of the wax. In FIG. 6, reference numeral 48 denotes a
separator for removing moisture and the like after the synthetic
reaction.
[0098] Referring to FIG. 7, it is shown from marks at the right
side that the wax is present in an amount of about 50% after
primary reaction in the LT-FT reactor 620, and it is shown from
marks at the left side that the amount of the wax is reduced to
about 10% and the amount of naphtha is increased after the
secondary reaction in the HT-FT reactor 640.
[0099] The LT-FT reactor 620 may be disposed at a downstream side
of the HT-FT reactor 640 depending upon desired properties of the
synthetic crude oil. Examples of the above case may include the
case of trying to produce a light synthetic crude oil such as
gasoline, naphtha, or diesel in large amounts.
[0100] According to details of the second embodiment, the control
unit 900 is provided with a wax detection unit 920 detecting wax
content, an unreacted gas detection unit 940 detecting unreacted
gas content, and a driving unit 960. The wax detection unit 920 and
the unreacted gas detection unit 940 are not limited to hardware
such as a specific sensor and may include a database in which data
of changes in content for each component of the synthetic crude oil
are collected and software.
[0101] According to details of the second embodiment, the control
unit 900 maintains wax content at a minimum level to a degree to
which unreacted gas content is maintained within a predetermined
range. As shown in FIG. 3, as wax content of the synthetic crude
oil is decreased, transport efficiency is reduced due to increasing
content of unreacted gas such as LPG. Thus, the control unit
maintains wax content at an optimal level to a degree to which
content of unreacted gas is maintained within a predetermined
range. It should be understood that wax content must also be
maintained within a range capable of securing flowability of the
synthetic crude oil.
[0102] As such, both the LT-FT reactor 620 and the HT-FT reactor
640 are used commercially in on-shore facilities and thus have low
risk when applied to off-shore facilities. Thus, it is not
necessary to secure flowability through an upgrading process, which
is unproven in off-shore facilities, and it is possible to reduce
CAPEX and OPEX required for establishment of an upgrading
system.
[0103] Although some embodiments have been described, it will be
apparent to those skilled in the art that these embodiments are
given by way of illustration only, and that various modifications,
changes, alterations, and equivalent embodiments can be made
without departing from the spirit and scope of the invention. The
scope of the invention should be limited only by the accompanying
claims and equivalents thereof.
* * * * *