AU2007232928B2 - Liquid fuel synthesis system - Google Patents

Description

OSP-27756AU SPECIFICATION LIQUID FUEL SYNTHESIZING SYSTEM 5 TECHNICAL FIELD [0001] The present invention relates to a liquid fuel synthesizing system for synthesizing liquid fuels from hydrocarbon raw materials, such as natural gas. Priority is claimed on Japanese Patent Application No. 2006-95534, filed March 30, 2006, the content of which is incorporated herein by reference. 10 BACKGROUND ART OF THE INVENTION [0002] As one of the methods for synthesizing liquid fuel from natural gas, a GTL (Gas-To-Liquid: liquid fuel synthesis) technique of reforming natural gas to produce synthesis gas including carbon monoxide gas (CO) and hydrogen gas (H 2 ) as main 15 components, synthesizing liquid hydrocarbons using this synthesis gas as a source gas by the Fischer-Tropsch synthesis reaction (hereafter referred to as "FT synthesis reaction"), and further hydrogenating and hydrocracking the liquid hydrocarbons to manufacture liquid fuel products, such as naphtha (rough gasoline), kerosene, gas oil, and wax, has recently been developed. 20 [0003] In a conventional liquid fuel synthesizing system using the GTL technique, when recovering the heat of the emission gas discharged from a reformer which reforms natural gas to produce synthesis gas containing carbon monoxide gas and hydrogen gas as main components, or the reaction heat generated in a reactor where, for example, liquid fuel synthesis reaction, such as an FT synthesis reaction, is performed, the heat is 25 recovered as steam, using apparatuses such as heat exchangers.

2 DISCLOSURE OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION [0004] However, since the pressure of the steam generated from an apparatus (for 5 example, a waste heat boiler) which recovers the waste heat of the reformer, or an apparatus (for example, a heat transfer pipe) which recovers the reaction heat of the reactor is, for example, steam having a relatively low pressure of about 1.2 MPaG (hereinafter referred to us "medium-pressure steam"), the steam is not utilized effectively, but is mostly cooled, and discarded as a condensed drain. 10 [0005] Thus, the present invention has been made in view of such a problem, and aims at providing a liquid fuel synthesizing system which synthesizes liquid fuel from a hydrocarbon raw material, such as natural gas, which makes it possible to effectively utilize the medium-pressure steam generated from an apparatus which recovers the waste is heat of a reformer, or an apparatus which recovers the reaction heat of a reactor, thereby improving the thermal efficiency of the whole liquid fuel synthesizing system. MEANS FOR SOLVING THE PROBLEMS 20 [0006] A first aspect of a liquid fuel synthesizing system of the present invention includes: a reformer that reforms a hydrocarbon raw material to produce synthesis gas including carbon monoxide gas and hydrogen gas as main components; a waste heat recovery apparatus that recovers the waste heat of the synthesis gas supplied from the reformer; a reactor that synthesizes liquid hydrocarbons from the carbon monoxide gas 25 and hydrogen gas included in the synthesis gas; and a heat treatment apparatus that performs predetermined heat treatment using medium-pressure steam having a pressure of 1.2 to 2.5 MPaG obtained by pressure reduction of high-pressure steam having a pressure of 3.4 to 10 MPaG generated in the waste heat recovery apparatus.

OSP-27756AU 3 [0007] In the first aspect of the liquid fuel synthesizing system of the present invention, when the waste heat recovery apparatus, such as a waste heat boiler, recovers the waste heat of the synthesis gas supplied from the reformer, the apparatus generates high-pressure steam (high-pressure steam). According to the present invention, this 5 high-pressure steam can be used as a heating source of a predetermined heat treatment apparatus in the liquid fuel synthesizing system, thereby improving the thermal efficiency of the whole liquid fuel synthesizing system. [0008] The first aspect of the liquid fuel synthesizing system invention may further include a CO 2 removal unit having an absorption column that separates carbon dioxide 10 gas from the synthesis gas supplied from the waste heat recovery apparatus by using an absorbent; and a regeneration column that heats the absorbent including the carbon dioxide gas separated in the absorption column to diffuse the carbon dioxide gas. In addition, the heat treatment apparatus may be the regeneration column. According to the present invention, the high-pressure steam from the waste heat recovery apparatus 15 can be used as a heating source when an absorbent is heated in the regeneration column. [0009] The first aspect of the liquid fuel synthesizing system of the present invention may further include a rectifying column that heats the liquid hydrocarbons synthesized in the reactor to fractionally distill the liquid hydrocarbons into two or more kinds of liquid fuels whose boiling points are different from each other. In addition, the heat treatment 20 apparatus may be the rectifying column. According to the present invention, the high-pressure steam from the waste heat recovery apparatus can be used as a heating source when liquid hydrocarbons are heated in the rectifying column. [0010] A second aspect of a liquid fuel synthesizing system of the present invention includes: a reformer that reforms a hydrocarbon raw material to produce synthesis gas 25 including carbon monoxide gas and hydrogen gas as main components; a reactor that 4 synthesizes liquid hydrocarbons from the carbon monoxide gas and hydrogen gas included in the synthesis gas; a reaction heat recovery apparatus that is provided in the reactor to recover the reaction heat of a synthesis reaction of the liquid hydrocarbons; and a heat treatment apparatus that performs predetermined heat treatment using medium 5 pressure steam having a pressure of 1.0 to 2.5 MPaG generated in the reaction heat recovery apparatus. [0011] In the second aspect of the liquid fuel synthesizing system of the present invention, when the reaction heat of recovery apparatus, such as a heat transfer pipe, 10 recover the reaction heat of the reactor, it generates a relatively lower pressure steam (medium-pressure steam). According to the present invention, this medium-pressure steam can be used as a heating source of a predetermined heat treatment apparatus in the liquid fuel synthesizing system, thereby improving the thermal efficiency of the whole liquid fuel synthesizing system. 15 [0012] The second aspect of the liquid fuel synthesizing system of the present invention may further include a rectifying column that heats the liquid hydrocarbons synthesized in the reactor to fractionally distill the liquid hydrocarbons into two or more kinds of liquid fuels whose boiling points are different from each other. In addition, the heat treatment 20 apparatus may be the rectifying column. According to the present invention, the medium pressure steam from the reaction heat recovery apparatus can be used as a heating source when liquid hydrocarbons are heated in the rectifying column. [0013] In the second aspect of the liquid fuel synthesizing system of the present 25 invention, the rectifying column may include a pressure reducing apparatus for a rectifying column (for example, a vacuum pump, etc.) which reduces the pressure, i.e., pressure within the rectifying column. Accordingly, the boiling points of liquid fuel in the rectifying column can be lowered, and steam having low energy such as the medium pressure steam can also be utilized as a heating source. Moreover, since the OSP-27756AU 5 boiling points of liquid fuel can be lowered, the liquid fuel can be distilled fractionally with less heat, and the liquid fuel seldom needs to be subjected to heat history. Accordingly, the quality of refined liquid fuel products can be improved. [0014] The second aspect of the liquid fuel synthesizing system of the present invention 5 may further include a CO 2 removal unit having an waste heat recovery apparatus that recovers the waste heat of the synthesis gas supplied from the reformer; an absorption column that separates carbon dioxide gas from the synthesis gas supplied from the waste heat recovery apparatus using an absorbent; and a regeneration column that heats the absorbent including the carbon dioxide gas separated in the absorption column to diffuse 10 the carbon dioxide gas. The heat treatment apparatus may be the regeneration column. According to the present invention, the medium-pressure steam from the reaction heat recovery apparatus can be used as a heating source when an absorbent is heated in the regeneration column. [0015] Further, in the second aspect of the liquid fuel synthesizing system of the present 15 invention, the regeneration column may include a pressure reducing apparatus for a regeneration column (for example, a vacuum pump, etc.) that reduces the pressure within the regeneration column. Accordingly, the boiling points of the absorbent can be lowered, and steam having low energy such as the medium-pressure steam can also be utilized as a heating source. 20 [0016] Further, a steam pressure reducing apparatus which reduces the pressure of the steam generated in the waste heat recovery apparatus may be disposed between the waste heat recovery apparatus and the heat treatment apparatus. ADVANTAGEOUS EFFECTS OF THE INVENTION 25 [0017] According to the present invention, in a liquid fuel synthesizing system which OSP-27756AU 6 synthesizes liquid fuel from a hydrocarbon raw material, such as natural gas, the pressure of steam generated from an apparatus which recovers the waste heat of a reformer, or an apparatus which recovers the reaction heat of a reactor can be utilized as a heating source of a heat treatment apparatus within the liquid fuel synthesizing system. Accordingly, 5 according to the present invention, the medium-pressure steam can be used effectively, thereby improving the thermal efficiency of the whole liquid fuel synthesizing system. BRIEF DESCRIPTION OF THE DRAWINGS [0018] [FIG. 1] FIG 1 is a schematic diagram showing the overall configuration of a 10 liquid fuel synthesizing system according to an embodiment of the present invention. [FIG. 2] FIG. 2 is a block diagram showing outlines of the utilization of steam in the liquid fuel synthesizing system according to the embodiment of the present invention. DESCRIPTION OF THE REFERENCE SYMBOLS 15 [0019] 1: LIQUID FUEL SYNTHESIZING SYSTEM 3: SYNTHESIS GAS PRODUCTION UNIT 5: FT SYNTHESIS UNIT 7: UPGRADING UNIT 10: DESULFURIZING REACTOR 20 12: REFORMER 14: WASTE HEAT BOILER 16 and18: GAS-LIQUID SEPARATORS 20: CO 2 REMOVAL UNIT 22: ABSORPTION COLUMN 25 24: REGENERATION COLUMN OSP-27756AU 7 26: HYDROGEN SEPARATING APPARATUS 30: BUBBLE COLUMN REACTOR 32: HEAT TRANSFER PIPE 34 and 38: GAS-LIQUID SEPARATORS 5 36: SEPARATOR 40: FIRST RECTIFYING COLUMN 50: WAX COMPONENT HYDROCRACKING REACTOR 52: KEROSENE AND GAS OIL FRACTION HYDROTREATING REACTOR 10 54: NAPHTHA FRACTION HYDROTREATING REACTOR 56, 58 and 60 GAS-LIQUID SEPARATORS 70: SECOND RECTIFYING COLUMN 72: NAPHTHA STABILIZER 144: STEAM PRESSURE REDUCING APPARATUS 15 242, 402 and 702: HEAT EXCHANGERS 244: PRESSURE REDUCING APPARATUS FOR A REGENERATION COLUMN 404: PRESSURE REDUCING APPARATUS FOR FIRST RECTIFYING COLUMN 20 704: PRESSURE REDUCING APPARATUS FOR SECOND RECTIFYING COLUMN DESCRIPTION OF THE PREFERRED EMBODIMENTS [0020] Hereinafter, preferred embodiments of the present invention will be described in 25 detail with reference to the accompanying drawings. In addition, in the present OSP-27756AU 8 specification and drawings, duplicate description is omitted by giving the same reference numerals to constituent parts having substantially the same functional configurations. [0021] First, with reference to FIG. 1, the overall configuration and operation of a liquid fuel synthesizing system 1 which carries out a GTL (Gas-To-Liquid) process according to 5 an embodiment of the present invention will be described. FIG. I is a schematic diagram showing the overall configuration of the liquid fuel synthesizing system 1 according to the present embodiment. [0022] As shown in FIG. 1, the liquid fuel synthesizing system I according to the present embodiment is a plant facility which carries out the GTL process which converts 10 a hydrocarbon raw material, such as natural gas, into liquid fuels. This liquid fuel synthesizing system 1 includes a synthesis gas production unit 3, an FT synthesis unit 5, and an upgrading unit 7. The synthesis gas production unit 3 reforms natural gas, which is a hydrocarbon raw material, to produce synthesis gas including carbon monoxide gas and hydrogen gas. The FT synthesis unit 5 produces liquid hydrocarbons from the 15 above synthesis gas by the Fischer-Tropsch synthesis reaction (hereafter referred to as "FT synthesis reaction"). The upgrading unit 7 hydrogenates and hydrocracks the liquid hydrocarbons produced by the FT synthesis reaction to manufacture liquid fuel products (naphtha, kerosene, gas oil, wax, etc.). Hereinafter, constituent parts of each of these units will be described. 20 [0023] First, the synthesis gas production unit 3 will be described. The synthesis gas production unit 3 mainly includes, for example, a desulfurizing reactor 10, a reformer 12, a waste heat boiler 14 as an example of a waste heat recovery apparatus, gas-liquid separators 16 and 18, a CO 2 removal unit 20, and a hydrogen separating device 26. The desulfurizing reactor 10 is composed of a hydrogenation desulfurizer, etc., and removes a 25 sulfur component from natural gas as a raw material. The reformer 12 reforms the OSP-27756AU 9 natural gas supplied from the desulfurizing reactor 10, to produce synthesis gas including carbon monoxide gas (CO) and hydrogen gas (H 2 ) as main components. The waste heat boiler 14 recovers heat duty of the synthesis gas produced by the reformer 12, to manufacture high-pressure steam. The gas-liquid separator 16 separates the water 5 heated by heat exchange with the synthesis gas in the waste heat boiler 14 into gas (high-pressure steam) and liquid. The gas-liquid separator 18 removes condensed components from the synthesis gas cooled down in the waste heat boiler 14, and supplies a gas component to the CO 2 removal unit 20. The CO 2 removal unit 20 has an absorption column 22 which removes carbon dioxide gas from the synthesis gas supplied 10 from the gas-liquid separator 18 by absorption, and a regeneration column 24 which heats the absorbent including the carbon dioxide gas with, for example, steam to extract and regenerate the carbon dioxide gas. The hydrogen separating apparatus 26 separates a part of the hydrogen gas included in the synthesis gas from the synthesis gas, the carbon dioxide gas of which has been separated by the CO 2 removal unit 20. 15 [0024] Among them, the reformer 12 reforms natural gas by using carbon dioxide and steam to produce high-temperature synthesis gas including carbon monoxide gas and hydrogen gas as main components, by a steam and carbon-dioxide-gas reforming method expressed by the following chemical reaction formulas (1) and (2). In addition, the reforming method in this reformer 12 is not limited to the example of the above steam 20 and carbon-dioxide-gas reforming method. For example, a steam reforming method, a partial oxidation method (POX) using oxygen, an autothermal reforming method (ATR) that is a combination of the partial oxidation method and the steam reforming method, a carbon-dioxide-gas reforming method, and the like can also be utilized. [0025] CH 4 + H 2 0 -CO + 3H 2 -- ' (1) 25 CH 4 + C02 -2CO + 2H 2 '-' (2) OSP-27756AU 10 [0026] Further, a steam pressure reducing apparatus 144 is provided at the tip of the gas-liquid separator 16. For example, the high-pressure steam generated from the waste heat boiler 14 has a pressure of about 3.4 to 10 MPaG, and the steam pressure reducing apparatus 144 for reducing the pressure of this high-pressure steam to make it into 5 medium-pressure steam having, for example, a pressure of about 1.2 to 2.5 MPaG is provided. [0027] Further, as an absorbent used to absorb and remove carbon dioxide gas in the

CO

2 removal unit 20, generally, a basic organic solvent is used. Such a basic organic solvent may include, for example, amine-based solvents, such as monoethanolamine, 10 catecholamine, tryptamine, arylamine, and alkanolamine. The CO 2 removal unit 20 uses, for example, the above amine-based solvents as an absorbent, and absorbs carbon dioxide gas to generate carbamic acid, by the reaction expressed by the following chemical reaction formula (3). In addition, the reaction shown in the following reaction formula (3) is an equilibrium reaction. 15 [0028] RNH 2 + CO 2 -> RNHCOOH - (3) [0029] Further, the hydrogen separating apparatus 26 is provided on a line branched from a main pipe which connects the CO 2 removal unit 20 or gas-liquid separator 18 with the bubble column reactor 30. This hydrogen separating apparatus 26 can be composed of, for example, a hydrogen PSA (Pressure Swing Adsorption) device which performs 20 adsorption and desorption of hydrogen by using a pressure difference. This hydrogen PSA device has adsorbents (zeolitic adsorbent, activated carbon, alumina, silica gel, etc.) within a plurality of adsorption columns (not shown) which are arranged in parallel. By sequentially repeating processes including pressurizing, adsorption, desorption (pressure reduction), and purging of hydrogen in each of the adsorption columns, high-purity (for 25 example, about 99.999%) hydrogen gas separated from the synthesis gas can be OSP-27756AU 11 continuously supplied to a reactor. [0030] Next, the FT synthesis unit 5 will be described. The FT synthesis unit 5 mainly includes, for example, the bubble column reactor 30, a gas-liquid separator 34, a separator 36, a gas-liquid separator 38, and a first rectifying column 40. The bubble 5 column reactor 30 carries out an FT synthesis reaction of the synthesis gas produced in the above synthesis gas production unit 3, i.e., carbon monoxide gas and hydrogen gas, to produce liquid hydrocarbons. The gas-liquid separator 34 separates the water circulated and heated through a heat transfer pipe 32, as an example of the reaction heat recovery apparatus disposed in the bubble column reactor 30, into steam (medium-pressure steam) 10 and liquid. The separator 36 is connected to a central part of the bubble column reactor 30, and separates a catalyst and a liquid hydrocarbon product. The gas-liquid separator 38 is connected to an upper part of the bubble column reactor 30, and cools down unreacted synthesis gas and gaseous hydrocarbon product. The first rectifying column 40 distills the liquid hydrocarbons supplied via the separator 36 and the gas-liquid 15 separator 38 from the bubble column reactor 30, and separates and refines the liquid hydrocarbons into individual product fractions according to boiling points. [0031] Among them, the bubble column reactor 30, which is an example of a reactor which converts synthesis gas to liquid hydrocarbons, functions as a reactor which produces liquid hydrocarbons from synthesis gas by the FT synthesis reaction. This 20 bubble column reactor 30 is composed of, for example, a slurry bubble column reactor in which slurry consisting of a catalyst and medium oil is reserved inside a column. This bubble column reactor 30 produces liquid hydrocarbons from synthesis gas by the FT synthesis reaction. In detail, in this bubble column reactor 30, the synthesis gas as a source gas is supplied as bubbles from a dispersing plate at the bottom of the bubble 25 column reactor 30, and ascends through the slurry consisting of a catalyst and medium OSP-27756AU 12 oil, and during this ascent, the synthesis gas included in the bubbles is dissolved in the slurry, and hydrogen gas and carbon monoxide gas cause a synthesis reaction with catalyst, as shown in the following chemical reaction formula (4). [0032] 2nH2 + nCO -> (-CH 2 -)n + nH20 -- (4) 5 [0033] Since this FT synthesis reaction is an exothermic reaction, the bubble column reactor 30, which is a heat exchanger-type reactor within which the heat transfer pipe 32 is disposed, is adapted such that, for example, water (BFW: Boiler Feed Water) is supplied as a refrigerant so that reaction heat of the above FT synthesis reaction can be recovered as medium-pressure steam by heat exchange between slurry and water. 10 [0034] Finally, the upgrading unit 7 will be described. The upgrading unit 7 includes, for example, a WAX component hydrocracking reactor 50, a kerosene and gas oil fraction hydrotreating reactor 52, a naphtha fraction hydrotreating reactor 54, gas-liquid separators 56, 58 and 60, a second rectifying column 70, and a naphtha stabilizer 72. The WAX component hydrocracking reactor 50 is connected to a lower part of the first 15 rectifying column 40. The kerosene and gas oil fraction hydrotreating reactor 52 is connected to a central part of the first rectifying column 40. The naphtha fraction hydrotreating reactor 54 is connected to an upper part of the first rectifying column 40. The gas-liquid separators 56, 58 and 60 are provided so as to correspond to the hydrogenation reactors 50, 52 and 54, respectively. The second rectifying column 70 20 separates and refines the liquid hydrocarbons supplied from the gas-liquid separators 56 and 58 according to boiling points. The naphtha stabilizer 72 rectifies liquid hydrocarbons of a naphtha fraction supplied from the gas-liquid separator 60 and the second rectifying column 70. Then, the naphtha stabilizer 72 discharges components lighter than butane towards flare gas (emission gas), and to separate and recover 25 components having a carbon number of five or more as a naphtha product.

OSP-27756AU 13 [0035] Next, a process (GTL process) of synthesizing liquid fuel from natural gas by the liquid fuel synthesizing system 1 configured as above will be described. [0036] Natural gas (whose main component is CH 4 ) as a hydrocarbon raw material is supplied to the liquid fuel synthesizing system 1 from an external natural gas supply 5 source (not shown), such as a natural gas field or a natural gas plant. The above synthesis gas production unit 3 reforms this natural gas to manufacture synthesis gas (mixed gas including carbon monoxide gas and hydrogen gas as main components). [0037] Specifically, first, the above natural gas is supplied to the desulfurizing reactor 10 along with the hydrogen gas separated by the hydrogen separating apparatus 26. The 10 desulfurizing reactor 10 hydrogenates and desulfurizes a sulfur component included in the natural gas using the hydrogen gas, with a ZnO catalyst. By desulfurizing natural gas in advance in this way, it is possible to prevent from decreasing activity of a catalyst used in the reformer 12, the bubble column reactor 30, etc. because of sulfur. [0038] The natural gas (may also contain carbon dioxide) desulfurized in this way is 15 supplied to the reformer 12 after the carbon dioxide (CO 2 ) gas supplied from a carbon-dioxide supply source (not shown) and the steam generated in the waste heat boiler 14 are mixed to the desulfurized natural gas. The reformer 12 reforms natural gas by using carbon dioxide and steam to produce high-temperature synthesis gas including carbon monoxide gas and hydrogen gas as main components, by the above steam and 20 carbon-dioxide-gas reforming method. At this time, the reformer 12 is supplied with, for example, fuel gas for a burner disposed in the reformer 12 and air, and reaction heat required for the above steam and carbon-dioxide-gas reforming reaction, which is an endothermic reaction, is provided by the heat of combustion of the fuel gas in the burner. [0039] The high-temperature synthesis gas (for example, 900*C, 2.0 MPaG) produced 25 in the reformer 12 in this way is supplied to the waste heat boiler 14, and is cooled down OSP-27756AU 14 by the heat exchange with the water which circulates through the waste heat boiler 14 (for example, 400*C), thereby exhausting and recovering heat. At this time, the water heated by the synthesis gas in the waste heat boiler 14 is supplied to the gas-liquid separator 16. From this gas-liquid separator 16, a gas component is supplied to the 5 reformer 12 or other external devices as high-pressure steam (for example, 3.4 to 10.0 MPaG), and water as a liquid component is returned to the waste heat boiler 14. [0040] Meanwhile, the synthesis gas cooled down in the waste heat boiler 14 is supplied to the absorption column 22 of the CO 2 removal unit 20, or the bubble column reactor 30, after condensate components are separated and removed from the synthesis 10 gas in the gas-liquid separator 18. The absorption column 22 absorbs carbon dioxide gas included in the synthesis gas into the circulated absorbent, to remove the carbon dioxide gas from the synthesis gas. The absorbent including the carbon dioxide gas within this absorption column 22 is introduced into the regeneration column 24, the absorbent including the carbon dioxide gas is heated and subjected to stripping treatment 15 with, for example, steam, and the resulting diffused carbon dioxide gas is delivered to the reformer 12 from the regeneration column 24, and is reused for the above reforming reaction. Further, the absorbent from which the carbon dioxide gas has been extracted and regenerated is delivered to the absorption column 22, and is reused for removal of the above carbon dioxide gas. 20 [0041] The synthesis gas produced in the synthesis gas production unit 3 in this way is supplied to the bubble column reactor 30 of the above FT synthesis unit 5. At this time, the composition ratio of the synthesis gas supplied to the bubble column reactor 30 is adjusted to a composition ratio (for example, H2: CO = 2:1 (molar ratio)) suitable for the FT synthesis reaction. In addition, the pressure of the synthesis gas supplied to the 25 bubble column reactor 30 is raised to a pressure (for example, 3.6 MPaG) suitable for the OSP-27756AU 15 FT synthesis reaction by a compressor (not shown) provided in a pipe which connects the

CO

2 removal unit 20 with the bubble column reactor 30. [0042] Further, a part of the synthesis gas, the carbon dioxide gas of which has been separated by the above CO 2 removal unit 20, is also supplied to the hydrogen separating 5 apparatus 26. The hydrogen separating apparatus 26 separates the hydrogen gas included in the synthesis gas, by the adsorption and desorption (hydrogen PSA) utilizing a pressure difference as described above. This separated hydrogen is continuously supplied from a gas holder (not shown), etc. via a compressor (not shown) to various hydrogen-utilizing reaction devices (for example, the desulfurizing reactor 10, the WAX 10 component hydrocracking reactor 50, the kerosene and gas oil fraction hydrotreating reactor 52, the naphtha fraction hydrotreating reactor 54, etc.) which perform predetermined reactions utilizing hydrogen within the liquid fuel synthesizing system 1. [0043] Next, the above FT synthesis unit 5 produces liquid hydrocarbons by the FT synthesis reaction from the synthesis gas produced by the above synthesis gas production 15 unit 3. [0044] Specifically, the synthesis gas from which carbon dioxide gas has been separated in the above CO 2 removal unit 20 flows into the bubble column reactor 30 from the bottom of the reactor 30, and flows up through the catalyst slurry reserved in the bubble column reactor 30. At this time, within the bubble column reactor 30, the carbon 20 monoxide and hydrogen gas which are included in the synthesis gas react with each other by the FT synthesis reaction, thereby producing hydrocarbons. Moreover, by circulating water through the heat transfer pipe 32 of the bubble column reactor 30 at the time of this synthesis reaction, the reaction heat of the FT synthesis reaction is removed, and the water heated by this heat exchange is vaporized into steam. As for this water 25 vapor, the water separated in the gas-liquid separator 34 is returned to the heat transfer OSP-27756AU 16 pipe 32, and the vapor is supplied to an external device as medium-pressure steam (for example, 1.0 to 2.5 MPaG). [0045] The liquid hydrocarbons synthesized in the bubble column reactor 30 in this way are removed from the central part of the bubble column reactor 30, and are introduced 5 into the separator 36. The separator 36 separates the introduced liquid hydrocarbons into a catalyst (solid component) in the extracted slurry, and a liquid component including a liquid hydrocarbon product. A part of the separated catalyst is supplied to the bubble column reactor 30, and a liquid component thereof is supplied to the first rectifying column 40. From the top of the bubble column reactor 30, unreacted 10 synthesis gas, and a gas component of the synthesized hydrocarbons are introduced into the gas-liquid separator 38. The gas-liquid separator 38 cools down these gases, and then separates some condensed liquid hydrocarbons to introduce them into the first rectifying column 40. Meanwhile, as the gas component separated in the gas-liquid separator 38, unreacted synthesis gases (CO and H 2 ) are put into the bottom of the bubble 15 column reactor 30, and reused for the FT synthesis reaction. Further, the emission gas (flare gas) other than target products, which contains as a main component hydrocarbon gas having a low carbon number (less than C 4 ), is introduced into an external combustion facility (not shown), is combusted therein, and is then discharged to the atmosphere. [0046] Next, the first rectifying column 40 heats the liquid hydrocarbons (whose carbon 20 numbers are various) supplied via the separator 36 and the gas-liquid separator 38 from the bubble column reactor 30 as described above, to fractionally distill the liquid hydrogen using a difference in boiling point. Thereby, the first rectifying column 40 separates and refines the liquid hydrogen into a naphtha fraction (whose boiling point is less than about 315*C), a kerosene and gas oil fraction (whose boiling point is about 315 25 to 800*C), and a WAX component (whose boiling point is greater than about 800*C).

OSP-27756AU 17 The liquid hydrocarbons (mainly C 21 or more) as the WAX component extracted from the bottom of the first rectifying column 40 are transferred to the WAX component hydrocracking reactor 50, the liquid hydrocarbons (mainly C 11 to C 20 ) as the kerosene and gas oil fraction removed from the central part of the first rectifying column 40 are 5 transferred to the kerosene and gas oil fraction hydrotreating reactor 52, and the liquid hydrocarbons (mainly C 5 to Cio) as the naphtha fraction extracted from the upper part of the first rectifying column 40 are transferred to the naphtha fraction hydrotreating reactor 54. [0047] The WAX component hydrocracking reactor 50 hydrocracks the liquid 10 hydrocarbons as the WAX component with a large carbon number (approximately C 2 1 or more), which has been supplied from the lower part of the first rectifying column 40, by using the hydrogen gas supplied from the above hydrogen separating apparatus 26, to reduce the carbon number to less than C 20 . In this hydrocracking reaction, hydrocarbons with a large carbon number and with low molecular weight are generated 15 by cleaving C-C bonds of hydrocarbons with a large carbon number, using a catalyst and heat. A product including the liquid hydrocarbons hydrocracked by this WAX component hydrocracking reactor 50 is separated into gas and liquid in the gas-liquid separator 56, the liquid hydrocarbons of which are transferred to the second rectifying column 70, and the gas component (including hydrogen gas) of which is transferred to 20 the kerosene and gas oil fraction hydrotreating reactor 52 and the naphtha fraction hydrotreating reactor 54. [0048] The kerosene and gas oil fraction hydrotreating reactor 52 hydrotreats liquid hydrocarbons (approximately C 11 to C 20 ) as the kerosene and gas oil fractions having an approximately middle carbon number, which have been supplied from the central part of 25 the first rectifying column 40, by using the hydrogen gas supplied via the WAX OSP-27756AU 18 component hydrocracking reactor 50 from the hydrogen separating apparatus 26. This hydrotreating reaction is a reaction which adds hydrogen to unsaturated bonds of the above liquid hydrocarbons, to saturate the liquid hydrocarbons and to generate straight-chain saturated hydrocarbons. As a result, a product including the hydrotreated 5 liquid hydrocarbons is separated into gas and liquid in the gas-liquid separator 58, the liquid hydrocarbons of which are transferred to the second rectifying column 70, and the gas component (including hydrogen gas) of which is reused for the above hydrogenation reaction. [0049] The naphtha fraction hydrotreating reactor 54 hydrotreats liquid hydrocarbons 10 (approximately Cio or less) as the naphtha fraction with a low carbon number, which have been supplied from the upper part of the first rectifying column 40, by using the hydrogen gas supplied via the WAX component hydrocracking reactor 50 from the hydrogen separating apparatus 26. As a result, a product including the hydrotreated liquid hydrocarbons is separated into gas and liquid in the gas-liquid separator 60, the 15 liquid hydrocarbons of which are transferred to the naphtha stabilizer 72, which is a kind of rectifying column, and the gas component (including hydrogen gas) of which is reused for the above hydrogenation reaction. [0050] Next, the second rectifying column 70 distills the liquid hydrocarbons supplied from the WAX component hydrocracking reactor 50 and the kerosene and gas oil fraction 20 hydrotreating reactor 52 as described above. Thereby, the second rectifying column 70 separates and refines the liquid hydrogen into a naphtha fraction (whose boiling point is less than about 315'C) with a carbon number of 10 or less, kerosene (whose boiling point is about 315 to 450'C), and gas oil (whose boiling point is about 450 to 800*C). The gas oil is extracted from a lower part of the second rectifying column 70, and the 25 kerosene is extracted from a central part thereof. Meanwhile, a hydrocarbon gas with a OSP-27756AU 19 carbon number of 10 or more is extracted from the top of the second rectifying column 70, and is supplied to the naphtha stabilizer 72. [0051] Moreover, the naphtha stabilizer 72 distills the hydrocarbons with a carbon number of 10 or less, which have been supplied from the above naphtha fraction 5 hydrotreating reactor 54 and second rectifying column 70. Thereby, the naphtha stabilizer 72 separates and refines naphtha (C 5 to CIO) as a product. Accordingly, high-purity naphtha is extracted from a lower part of the naphtha stabilizer 72. Meanwhile, the emission gas (flare gas) other than products, which contains as a main component hydrocarbons with a carbon number lower than or equal to a predetermined 10 number or less (lower than or equal to C 4 ), is discharged from the top of the naphtha stabilizer 72. Further, the emission gas is introduced into an external combustion facility (not shown), is combusted therein, and is then discharged to the atmosphere. [0052] The process (GTL process) of the liquid fuel synthesizing system 1 has been described hitherto. By the GTL process, natural gas can be easily and economically 15 converted into clean liquid fuels, such as high-purity naphtha (Cs to CIO: rough gasoline), kerosene (C 1 to C 15 : kerosene), and gas oil (C 16 to C 20 : gas oil). Moreover, in the present embodiment, the above steam and carbon-dioxide-gas reforming method is adopted in the reformer 12. Thus, there are advantages in that carbon dioxide contained in natural gas to be used as a raw material can be effectively utilized, the composition 20 ratio (for example, H 2 :CO = 2:1 (molar ratio)) of a synthesis gas suitable for the above FT synthesis reaction can be efficiently produced in one reaction of the reformer 12, and a hydrogen concentration adjustor, etc. is unnecessary. [0053] Meanwhile, conventionally, the high-pressure steam generated with waste heat recovery of the synthesis gas produced by the reformer 12 by the waste heat boiler 14, 25 and the medium-pressure steam generated with reaction heat recovery of the FT synthesis OSP-27756AU 20 reaction in the bubble column reactor 30 by the heat transfer pipe 32 was not utilized effectively, and most thereof was collected and discarded as a condensed drain. In particular, since the medium-pressure steam is, for example, steam having a relatively low pressure of about 1.2 MPaG as described above, its energy was relative small, and its 5 utility value as a heating source, etc. was low. Further, the high-pressure steam generated by the heat recovery of the waste heat boiler 14 is often turned into medium-pressure steam using an independent pressure-reducing valve or an independent temperature-reducing apparatus, and the steam pressure reducing apparatus 144 by the combination thereof. 10 [0054] Thus, in the liquid fuel synthesizing system I according to the present embodiment, as shown in FIG. 1, the high-pressure steam ("A" circled in the drawing) generated at the time of the waste heat recovery by the waste heat boiler 14, or the medium-pressure steam ("B" circled in the drawing) generated with the reaction heat recovery by the heat transfer pipe 32 is used as a heating source of a heat treatment 15 apparatus which performs predetermined heat treatment using steam, such as the regeneration column 24 of the CO 2 removal unit 20, the first rectifying column 40, the second rectifying column 70, or the naphtha stabilizer 72. Thereby, the above high-pressure steam or medium-pressure steam is effectively used within the liquid fuel synthesizing system 1, improving thermal efficiency of the whole liquid fuel synthesizing 20 system 1 using the GTL technique. [0055] Hereinafter, with reference to FIG 2, the details of utilization of steam, such as the high-pressure steam generated at the time of the waste heat recovery by the waste heat boiler 14, and the medium-pressure steam generated at the time of the reaction heat recovery by the heat transfer pipe 32, in the liquid fuel synthesizing system 1 according 25 to the present embodiment, will be described. In addition, FIG. 2 is a block diagram OSP-27756AU 21 showing outlines of utilization of steam in the liquid fuel synthesizing system according to the embodiment of the present invention. [0056] First, the detailed configuration of the regeneration column 24, the first rectifying column 40, and the second rectifying column 70 according to the present 5 embodiment will be described. In addition, other configurations are as described above. [0057] As shown in FIG. 2, the regeneration column 24 includes a heat exchanger 242 as a heating means for performing heating when carbon dioxide gas is diffused from an absorbent including a large concentration of carbon dioxide gas. This heat exchanger 242 performs heat exchange in order to use the heat of high-temperature steam for 10 heating of the absorbent in the regeneration column, and the steam after the heat exchange is discharged as a drain via a steam trap, etc. In the present embodiment, the medium-pressure steam obtained by reducing the pressure of the high-pressure steam generated by the waste heat recovery of the waste heat boiler (WHB) 14 with the steam pressure reducing apparatus 144, or the medium-pressure steam generated by the reaction 15 heat recovery of the heat transfer pipe 32 is used as steam to be used as a heating source of the heat exchanger 242. The heat exchanger 242 can heat the absorbent in the regeneration column 24 to, for example, about 100 tol40*C using such medium-pressure steam. [0058] Further, the regeneration column 24 includes a pressure reducing apparatus 244 20 for a regeneration column which reduces the pressure in the regeneration column 24. As such a pressure reducing apparatus 244 for a regeneration column, for example, a vacuum pump can be used. As this vacuum pump, for example, an ejector pump can be used in which a high-pressure liquid current is generated by a pump, this liquid current is supplied to a nozzle, a pressure drop by the velocity energy of the liquid ejected at high 25 speed from the nozzle is utilized, and a pipeline which sucks air and gas, or its OSP-27756AU 22 condensate liquid is connected to this pressure-drop portion. As such, by reducing the pressure in the regeneration column 24 using the pressure reducing apparatus 244 for a regeneration column to lower the boiling point of the absorbent, even if steam having low holding energy like the above medium-pressure steam is used, regeneration of the 5 absorbent which has absorbed the carbon dioxide gas can be performed sufficiently. [0059] Further, the first rectifying column 40 includes a heat exchanger 402 as a heating means for fractionally distilling a mixture of a plurality of liquid hydrocarbons that are generated by the bubble column reactor 30 and are different in boiling point from one another. The second rectifying column 70 includes a heat exchanger 702 as a heating 10 means for fractionally distilling reaction products of the hydrogenation reactors 50, 52 and 54. These heat exchangers 402 and 702 perform heat exchange in order to use the heat of high-temperature steam for heating of the liquid hydrocarbons in the first rectifying column 40 and the second rectifying column 70, and the steam after the heat exchange is performed is discharged as water. In the present embodiment, the 15 medium-pressure steam obtained by reducing the pressure of the high-pressure steam generated by the waste heat recovery of the waste heat boiler (WIHB) 14 with the steam pressure reducing apparatus 144, or the medium-pressure steam generated by the reaction heat recovery of the heat transfer pipe 32 is used as steam to be used as heating sources of the heat exchangers 402 and 702. The heat exchangers 402 and 702 can heat the 20 liquid hydrocarbons in the first rectifying column 40 and the second rectifying column 70 to, for example, about 300*C using such medium-pressure steam. [0060] The first rectifying column 40 includes a pressure reducing apparatus 404 for a first rectifying column, which reduce the pressure, i.e., pressure in the first rectifying column 40. The second rectifying column 70 includes a pressure reducing apparatus 25 704 for a second rectifying column, which reduce the pressure, i.e., pressure in the OSP-27756AU 23 second rectifying column 70. As the pressure reducing apparatus 404 for a first rectifying column, and the pressure reducing apparatus 704 for a second rectifying column, for example, vacuum pumps can be used such as the pressure reducing apparatus 244 for a regeneration column. As such, the pressure reducing apparatus 404 for a first 5 rectifying column and the pressure reducing apparatus 704 for a second rectifying column are used to reduce the pressure, i.e., pressures within the first rectifying column 40 and the second rectifying column 70 to lower the boiling point of the liquid hydrocarbons to perform vacuum distillation, etc, whereby, even if steam having low holding energy like the above medium-pressure steam is used, the amount of heat 10 sufficient to fractionally distill liquid hydrocarbon components whose boiling points are different from one another can be supplied. Further, by lowering the boiling point of liquid hydrocarbons, the amount of heat given to the liquid hydrocarbons to be heated can be made low, and the frequency to which the liquid hydrocarbons are subjected to heat history can be reduced even further. Accordingly, the quality of refined liquid 15 hydrocarbon products can be improved. [0061] Hereinafter, a concrete method of utilizing steam, such as the high-pressure steam generated at the time of the waste heat recovery by the waste heat boiler 14, and the medium-pressure steam generated at the time of the reaction heat recovery by the heat transfer pipe 32, will be described. 20 [0062] As shown in FIG. 2, the natural gas from which a sulfur component has been removed by the desulfurizing reactor 10 is reformed by the reformer 12 to produce synthesis gas including carbon monoxide gas and hydrogen gas as main components. The waste heat of the synthesis gas produced by the reformer 12 is recovered by the waste heat boiler 14. Although the steam (high-pressure steam) generated by the waste 25 heat recovery of the waste heat boiler 14 has a high pressure of, for example, about 3.8 OSP-27756AU 24 MPaG its pressure is reduced to about 1.2 MPaG by the steam pressure reducing apparatus 144. Meanwhile, the synthesis gas from which waste heat has been recovered is delivered to the absorption column 22 of the CO 2 removal unit 20 where carbon dioxide gas is separated by the absorbent. 5 [0063] The absorbent which has absorbed the carbon dioxide gas and thus has become high in carbon dioxide gas concentration is delivered to the regeneration column 24 where regeneration of the absorbent is performed. In the regeneration column 24, the inside of the regeneration column 24 is made into a reduced the pressure by the pressure reducing apparatus 244 for a regeneration column, and carbon dioxide gas is discharged 10 from the absorbent while the absorbent including the carbon dioxide gas is heated using the heat exchanger 242. Further, the absorbent from which the carbon dioxide gas has been extracted and regenerated in the regeneration column 244 is delivered to the absorption column 22, and is reused for removal of the above carbon dioxide gas. [0064] The synthesis gas from which the carbon dioxide gas has been removed is 15 introduced into the bubble column reactor 30 where the FT synthesis reaction, i.e., the synthesis reaction of the liquid hydrocarbons, is performed. At this time, since the FT synthesis reaction is an exothermic reaction, the reaction heat of the FT synthesis reaction is recovered by the heat transfer pipe 32, and is controlled so that the temperature of the liquid hydrocarbons in the bubble column reactor 30 may not rise too 20 much. Steam (medium-pressure steam) is generated by recovery of the reaction heat of this heat transfer pipe 32. [0065] The liquid hydrocarbons synthesized within the bubble column reactor 30, which are a mixture including various kinds of hydrocarbons having different carbon numbers (different boiling points), are delivered to the first rectifying column 40, and 25 fractional distillation is performed in the first rectifying column 40 using differences OSP-27756AU 25 between the boiling points. In the first rectifying column 40, the inside of the first rectifying column 40 is made into a vacuum state by the pressure reducing apparatus 404 for a first rectifying column, and a mixture of liquid hydrocarbons having different boiling points is fractionally distilled while the liquid hydrocarbon mixture is heated 5 using the heat exchanger 402. [0066] The hydrocarbon components distilled fractionally in the first rectifying column 40 also include a component having a still larger carbon number, and a component having unsaturated bonds, such as olefin, other than naphtha kerosene, and gas oil, which are still final products of the liquid fuel synthesizing system 1. Therefore, the 10 hydrogenation reactors 50, 52 and 54 decompose the hydrocarbon components into components having a lower carbon number by hydrocracking of hydrocarbons or making them into saturated hydrocarbon components by hydrogenation. [0067] Further, the reaction products in these hydrogenation reactors 50, 52 and 54 are further delivered to the second rectifying column 70, where they are fractionally distilled 15 into final liquid hydrocarbon products (liquid fuel products), such as naphtha, kerosene, and gas oil. In the second rectifying column 70, the inside of the second rectifying column 70 is placed under a reduced pressure state by the pressure reducing apparatus 704 for a second rectifying column, and a mixture of liquid hydrocarbons having different boiling points is fractionally distilled while the liquid hydrocarbon mixture is 20 heated using the heat exchanger 702. [0068] As described above, the medium-pressure steam obtained by reducing the pressure of the high-pressure steam generated by the waste heat recovery of the waste heat boiler 14 with the steam pressure reducing apparatus 144, or the medium-pressure steam generated by the reaction heat recovery of the heat transfer pipe 32 is used as 25 steam to be used as heating source to be used by the heat exchanger 242 in the OSP-27756AU 26 regeneration column 24, the heat exchanger 402 in the first rectifying column 40, and the heat exchanger 702 in the second rectifying column 70. Accordingly, the medium-pressure steam that conventionally had few applications, and was seldom used effectively because the pressure of the steam was relatively low, can be used effectively 5 within the liquid hydrocarbon system 1. As a result, the thermal efficiency of the whole liquid hydrocarbon system 1 can be improved remarkably. Further, the medium-pressure steam having small energy can be used for heating in the first rectifying column 40 or heating in the second rectifying column 70, thereby reducing the heat history that liquid hydrocarbons are subjected to, and improving the quality of final 10 products. [0069] Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, it is needless to say that the present invention is not limited to such embodiments. It is apparent to those skilled in the art that various alternations or modifications can be made within the scope as set 15 forth in the claims, and it will be understood that these alternations or modifications naturally belong to the technical scope of the present invention. [0070] For example, in the above embodiments, natural gas is used as a hydrocarbon raw material to be supplied to the liquid fuel synthesizing system 1. However, the present invention is not limited to such an example. For example, other hydrocarbon 20 raw materials, such as asphalt and residual oil, may be used. [0071] Further, in the above embodiments, liquid hydrocarbons are synthesized by the FT synthesis reaction, using the bubble column reactor 30 as a bubble column reactor according to the present invention. However, the present invention is not limited to this example. Specifically, the present invention can also be applied to, for example, oxo 25 synthesis (hydroformylation reaction) "R-CH=CH 2 + CO + H 2 -+ R-CH 2

CH

2

CHO",

OSP-27756AU 27 methanol synthesis "CO + 2H 2 -) CH 3 0H", dimethylether (DME) synthesis "3CO + 3H 2 -+ CH 3 0CH 3 + C0 2 ", etc., as the synthesis reaction in the bubble column reactor. [0072] Further, in the above embodiment, the regeneration column 24 of the CO 2 removal unit 20, the first rectifying column 40, and the second rectifying column 70 are 5 given as examples of the heat treatment apparatus. However, the present invention is not limited to such examples. Any devices other than those above may be adopted as long as they perform a predetermined heat treatment in a liquid fuel synthesizing system using steam. For example, the medium-pressure steam can be used even in heating of the naphtha stabilizer 72, etc. 10 [0073] Further, in the above embodiments, the slurry bubble column reactor is used as the reactor which converts synthesis gas to liquid hydrocarbons. However, the present invention is not limited to such an example. For example, an FT synthesis reaction using a fixed bed type reactor, etc. may be performed. 15 INDUSTRIAL APPLICABILITY [0074] The present invention relates to a liquid fuel synthesizing system including: a reformer that reforms a hydrocarbon raw material to produce synthesis gas including carbon monoxide gas and hydrogen gas as main components; a waste heat recovery apparatus that recovers the waste heat of the synthesis gas supplied from the reformer; a 20 reactor that synthesizes liquid hydrocarbons from the carbon monoxide gas and hydrogen gas included in the synthesis gas; and a heat treatment apparatus that performs predetermined heat treatment using steam generated in the waste heat recovery apparatus. According to the liquid fuel synthesizing system of the present invention, the medium-pressure steam generated from an apparatus which recovers the waste heat of a 25 reformer, or an apparatus which recovers the reaction heat of a reactor can be used OSP-27756AU 28 effectively, thereby improving the thermal efficiency of the whole liquid fuel synthesizing system.

Claims (9)

1. A liquid fuel synthesizing system comprising: a reformer that reforms a hydrocarbon raw material to produce synthesis gas s including carbon monoxide gas and hydrogen gas as main components; a waste heat recovery apparatus that recovers the waste heat from the synthesis gas supplied from the reformer; a reactor that synthesizes liquid hydrocarbons from the carbon monoxide gas and hydrogen gas included in the synthesis gas; and 10 a heat treatment apparatus that performs a predetermined heat treatment using medium-pressure steam having a pressure of 1.2 to 2.5 MPaG obtained by pressure reduction of high-pressure steam having a pressure of 3.4 to 10 MPaG generated in the waste heat recovery apparatus. 15

2. The liquid fuel synthesizing system according to Claim 1, further comprising a CO 2 removal unit having an absorption column that separates carbon dioxide gas from the synthesis gas supplied from the waste heat recovery apparatus by using an absorbent, and a regeneration column that heats the absorbent including the carbon dioxide gas separated in the absorption column to diffuse the carbon dioxide gas, wherein 20 the heat treatment apparatus is the regeneration column.

3. The liquid fuel synthesizing system according to Claim I, further comprising a rectifying column that heats the liquid hydrocarbons synthesized in the reactor to fractionally distill the liquid hydrocarbons into two or more kinds of liquid fuels whose 25 boiling points are different from each other, wherein the heat treatment apparatus is the rectifying column.

4. A liquid fuel synthesizing system comprising: a reformer that reforms a hydrocarbon raw material to produce synthesis gas 30 including carbon monoxide gas and hydrogen gas as main components; a reactor that synthesizes liquid hydrocarbons from the carbon monoxide gas and hydrogen gas included in the synthesis gas; a reaction heat recovery apparatus that is provided in the reactor to recover the reaction heat of a synthesis reaction of the liquid hydrocarbons; and 30 a heat treatment apparatus that performs predetermined heat treatment using medium-pressure steam having a pressure of 1.0 to 2.5 MPaG generated in the reaction heat recovery apparatus.

5 5. The liquid fuel synthesizing system according to Claim 4, further comprising a rectifying column that heats the liquid hydrocarbons synthesized in the reactor to fractionally distill the liquid hydrocarbons into two or more kinds of liquid fuels whose boiling points are different from each other, wherein the heat treatment apparatus is the rectifying column. 10

6. The liquid fuel synthesizing system according to Claim 5, wherein the rectifying column includes a pressure reducing apparatus for a rectifying column that reduces the pressure within the rectifying column. 15

7. The liquid fuel synthesizing system according to Claim 4, further comprising a CO 2 removal unit having a waste heat recovery apparatus that recovers the waste heat of the synthesis gas supplied from the reformer; an absorption column that separates carbon dioxide gas from the synthesis gas emitted from the waste heat recovery apparatus using an absorbent, and a regeneration column that heats the absorbent including the carbon 20 dioxide gas separated in the absorption column to diffuse the carbon dioxide gas, wherein the heat treatment apparatus is the regeneration column.

8. The liquid fuel synthesizing system according to Claim 7, wherein the regeneration column includes a pressure reducing apparatus for a 25 regeneration column which reduces the pressure within the regeneration column.

9. A liquid fuel synthesizing system substantially as hereinbefore described with reference to the accompanying drawings. 30 Dated 24 January, 2011 Nippon Steel Engineering Co., Ltd. Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON