RU2425089C2 - Fuel oil synthesis system - Google Patents

Abstract

FIELD: oil and gas industry. ^ SUBSTANCE: invention refers to fuel oil synthesis system including the first reforming unit 12 which reforms hydrocarbon raw material in order to obtain synthesis gas containing gaseous carbon monoxide and gaseous hydrogen as the main components, bubble column reactor which synthesises liquid hydrocarbons from gaseous carbon monoxide and gaseous hydrogen, which are contained in synthesis gas, the first rectifying column 40 which heats liquid hydrocarbons synthesised in bubble column reactor 30 for fraction distillation of many kinds of fuel oils having various boiling temperatures, reaction device using hydrogen and performing the specified reaction with liquid fuel fraction by using gaseous hydrogen contained in synthesis gas, the second rectifying column 70 which purifies at least two liquid components separated and extracted from reaction devices using hydrogen so that many kinds of fuel oils and gas fraction are obtained; naphtha stabiliser to which fraction of the gas from the second rectifying column is supplied, and the above stabiliser is located downstream relative to the second rectifying column; the second reforming unit which reforms the gas leaving the naphtha stabiliser; and hydrogen separation device which separates gaseous hydrogen from synthesis gas obtained in the second reforming unit; at that, gas is taken from naphtha stabiliser and supplied via pipeline to the first reforming unit or the second reforming unit; synthesis gas taken from the second reforming unit is supplied via pipeline to reactor or hydrogen separating device, and gaseous hydrogen separated with hydrogen separation device is supplied via pipeline to reactor or reaction devices using hydrogen. ^ EFFECT: higher use efficiency of raw material and lower amount of emissions of carbon dioxide. ^ 4 cl, 4 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a liquid fuel synthesis system for synthesizing liquid fuels from hydrocarbon feedstocks such as natural gas.

Priority claimed is Japanese Patent Application No. 2006-95544, filed March 30, 2006, the contents of which are incorporated herein by reference.

BACKGROUND

As one of the methods for the synthesis of liquid fuels from natural gas, the GTL technology (Gas-In-Liquid: Synthesis of Liquid Fuels, LFG) of converting natural gas to produce synthesis gas including gaseous carbon monoxide (CO) and hydrogen gas ( H ₂₎ as main components, synthesizing liquid hydrocarbons using this synthesis gas as a source gas via the synthesis reaction of Fischer-Tropsch (hereinafter, referred to as "FT synthesis reaction") and subsequent hydrogenation and gidrokrekin and liquid hydrocarbons to produce liquid fuel products such as naphtha (raw gasoline), kerosene, gas oil, and wax.

Although liquid hydrocarbons immediately after the synthesis reaction become a mixture of many liquid hydrocarbons having different boiling points, a unit called a distillation column is used to separate this mixture. The off-gas (hereinafter referred to as “off-gas”), which is discharged from the top of this distillation column, is supplied to the flare rack and burned therein, then emitted into the atmosphere after components of liquid fuel products such as naphtha (untreated gasoline) , kerosene and gas oil, the number of carbon atoms of which is five or more, are separated and extracted.

DESCRIPTION OF THE INVENTION

PROBLEMS SOLVED BY THE INVENTION

However, for example, the exhaust gas contains gaseous hydrocarbons, etc. with the number of carbon atoms, for example, less than five. However, in the aforementioned conventional liquid fuel synthesis system, off-gas is burned and emitted. Therefore, gaseous hydrocarbons, which may be a raw material for liquid hydrocarbons, are disposed of uselessly. Not only is the raw material not used efficiently, but also the amount of carbon dioxide emissions increases as a result of burning off-gas.

Thus, the present invention has been made in view of the above problems and is directed to the development of a liquid fuel synthesis system suitable for efficiently utilizing a hydrocarbon component with a low number of carbon atoms contained in the aforementioned exhaust gas, thereby improving the utilization efficiency of the raw material and reducing the amount of dioxide emissions carbon.

MEANS FOR SOLVING PROBLEMS

The liquid fuel synthesis system according to the present invention includes a first reforming apparatus that converts a hydrocarbon feed material to produce synthesis gas including carbon monoxide gas and hydrogen gas as main components; a reactor that synthesizes liquid hydrocarbons from gaseous carbon monoxide and gaseous hydrogen contained in the synthesis gas; the first distillation column, which heats the liquid hydrocarbons synthesized in the reactor, for fractional distillation of many varieties of liquid fuels having different boiling points; a hydrogen using a reaction device that performs a given reaction with a hydrocarbon feed or liquid fuels using hydrogen gas contained in the synthesis gas; a second distillation column that purifies the liquid component separated and separated from the hydrogen-using reaction device; and a feed device that delivers gas discharged from the second distillation column to at least one unit from a first reformer, using a hydrogen reaction device and a reactor, as part of the raw material.

According to such an arrangement, the feed device delivers gas discharged from the second distillation column to at least one of the first reforming apparatus using a hydrogen reaction device and a reactor as part of the raw material. Since the gas discharged from the second distillation column contains a hydrocarbon component with four carbon atoms or less, the recovery efficiency of the hydrocarbon feed can be improved by returning the gas discharged from the second distillation column to a unit located upstream of the second distillation column .

In a liquid fuel synthesis system, a hydrogen-using reaction device may include at least one of a hydrogenation reactor of at least one of a plurality of liquid fuels and a desulfurization reactor that hydrogenates and desulphurizes the hydrocarbon feed to the first reforming apparatus.

The liquid fuel synthesis system may further include a naphtha stabilizer located downstream of the second distillation column, and the gas may be withdrawn from the naphtha stabilizer and fed to at least one of the first reforming apparatus using a hydrogen reaction device and a reactor as part of the feedstock material. Moreover, the liquid fuel synthesis system may further include a second reforming apparatus that converts the gas removed from the naphtha stabilizer. According to the present invention, the synthesis gas for the liquid fuel synthesis system can be improved by reforming the gas withdrawn from the naphtha stabilizer. Thus, since a hydrocarbon component with a low number of carbon atoms contained in the gas discharged from the naphtha stabilizer can be disposed of, the useless consumption of hydrocarbons as a raw material can be reduced and the efficiency of utilization of the raw material can be improved.

Further, the liquid fuel synthesis system may further include a hydrogen separation device that separates hydrogen gas from the synthesis gas obtained in the second reforming apparatus, and a feeding device may supply hydrogen gas separated by the hydrogen separation device to a reactor or using hydrogen reaction device. With this arrangement of the hydrogen separation apparatus, only hydrogen gas can be separated and purified from the synthesis gas obtained in the second reforming apparatus, and the supply device can supply hydrogen gas to each unit that consumes hydrogen gas. This can reduce the amount of hydrogen gas that must be reintroduced into the liquid fuel synthesis system.

The liquid fuel synthesis system may further include a hydrogen storage device that stores hydrogen gas separated by a hydrogen separation device.

In a liquid fuel synthesis system, a feed device may supply hydrogen gas stored in the hydrogen storage device to a hydrogen-using reaction device during the start-up period of the liquid fuel synthesis system. With this arrangement, a hydrogen-using reaction device can be quickly put into operation before gaseous hydrogen begins to be supplied from the reforming apparatus. Therefore, the production efficiency of the liquid fuel synthesis system can be improved.

Advantageous Effects of the Invention

According to the liquid fuel synthesis system of the present invention, the hydrocarbon component with a low number of carbon atoms contained in the exhaust gas can be efficiently used without emission, so that the utilization efficiency of the raw material can be improved and the amount of carbon dioxide emissions can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic diagram showing an overall arrangement of a liquid fuel synthesis system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an exemplary arrangement of a feeding device that supplies gas discharged from the top of a distillation column in a liquid fuel synthesis system according to an embodiment of the present invention.

FIG. 3 is a block diagram showing yet another exemplary arrangement of a feed device that supplies gas discharged from the top of a distillation column in a liquid fuel synthesis system according to an embodiment of the present invention.

FIG. 4 is a block diagram showing yet another exemplary arrangement of a feed device that supplies gas discharged from the top of a distillation column in a liquid fuel synthesis system according to an embodiment of the present invention.

DESCRIPTION OF CODE SYMBOLS

1: LIQUID FUEL SYNTHESIS SYSTEM

3: SYNTHESIS GAS UNIT

5: FISHER-TROPSH SYNTHESIS BLOCK (FT-SYNTHESIS)

7: QUALITY BLOCK

10: DESULFURIZATION REACTOR

12: FIRST REFORMING MACHINE

14: COOLING BOILER USING WASTE GAS

16 and 18: GAS-LIQUID SEPARATORS

20: CO ₂ REMOVAL UNIT

22: SIPPING COLUMN

24: REGENERATION COLUMN

26: HYDROGEN SEPARATION DEVICE

30: Bubbling Column Reactor

32: TUBULAR HEAT EXCHANGER

34 and 38: GAS-LIQUID SEPARATOR

36: SEPARATOR

40: FIRST RECTIFICATION COLUMN

50: Wax Hydrocracking Reactor

52: KEROSIN AND GAS OIL FACTION HYDRATION REACTOR

54: LIGROIN FACTION HYDROGEN REACTOR

56, 58 and 60: GAS-LIQUID SEPARATORS

70: SECOND RECTIFICATION COLUMN

72: NAFTA STABILIZER

100: EXHAUST GAS DISTRIBUTION AND SUPPLY ROUTE

102: SECOND REFORMING APPARATUS

104: SYNTHESIS GAS FEEDING ROUTE

106: HYDROGEN SEPARATION DEVICE

108: CARBON MONOXIDE SUBMISSION ROUTE

110: HYDROGEN STORAGE DEVICE

112: GAS HYDROGEN FEEDING ROUTE

DESCRIPTION OF PREFERRED EMBODIMENTS

Next, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, a duplicate description is excluded in the present description and drawings by assigning the same reference numbers to components having substantially the same functional configurations.

First, with the involvement of FIG. 1, the general arrangement and operation of a liquid fuel synthesis system 1 that performs a GTL process (Gas-In-Liquid, SLF) according to an embodiment of the present invention will be described. 1 is a schematic diagram showing an overall arrangement of a liquid fuel synthesis system 1 according to the present invention.

As shown in FIG. 1, the liquid fuel synthesis system 1 according to the present embodiment is an industrial plant that performs a GTL process that converts a hydrocarbon feed material, such as natural gas, to liquid fuels. This liquid fuel synthesis system 1 includes a synthesis gas production unit 3, an FT synthesis unit 5, and a quality improvement unit 7. Block 3 for the production of synthesis gas is reformed natural gas, which is a hydrocarbon feedstock, to produce synthesis gas comprising gaseous carbon monoxide and gaseous hydrogen. FT synthesis block 5 produces liquid hydrocarbons from the above synthesis gas using the Fischer-Tropsch synthesis reaction (hereinafter referred to as the “FT synthesis reaction”). The quality improvement unit 7 subjected to hydrogenation and hydrocracking liquid hydrocarbons obtained by the FT synthesis reaction to produce liquid fuel products (naphtha, kerosene, gas oil, wax, etc.). Next, the components of each of these installations will be described.

Firstly, block 3 for producing synthesis gas will be described. Block 3 for the production of synthesis gas mainly includes, for example, a desulfurization reactor 10, a first reforming apparatus 12 (hereinafter referred to as a “reforming apparatus 12”), a boiler 14 using exhaust gas heat, gas-liquid separators 16 and 18, a device 20 for removing CO ₂ and a device 26 for separating hydrogen. The desulfurization reactor 10 consists of a hydrodesulfurizer, etc. and removes the sulfur component from natural gas as a raw material. The reforming apparatus 12 converts the natural gas supplied from the desulfurization reactor 10 to produce synthesis gas comprising gaseous carbon monoxide (CO) and gaseous hydrogen (H ₂ ) as main components. The boiler 14, which uses the heat of the exhaust gases, utilizes the heat content of the synthesis gas produced in the reforming apparatus 12 to produce high pressure steam. The gas-liquid separator 16 separates the water heated by heat exchange with the synthesis gas in the boiler 14, which uses the heat of the exhaust gases, into gas (high pressure steam) and liquid. The gas-liquid separator 18 removes the condensed components from the synthesis gas cooled in the boiler 14 using the heat of the exhaust gases, and supplies the gaseous component to the block 20 to remove CO ₂ . The CO ₂ removal unit 20 has an absorption column 22, which removes carbon dioxide gas from the synthesis gas supplied from the gas-liquid separator 18 by absorption, and a regeneration column 24 that releases and regenerates carbon dioxide gas from the absorber containing carbon dioxide gas. A hydrogen separator 26 separates a portion of the hydrogen gas contained in the synthesis gas from the synthesis gas from which the carbon dioxide gas was separated by the CO ₂ unit 20.

Among them, the reforming apparatus 12 converts natural gas using carbon dioxide and water vapor to produce high temperature synthesis gas including carbon monoxide gas and hydrogen gas as main components, a method for reforming water vapor and carbon dioxide gas, which is described by the following chemical reaction equations (1) and (2). In addition, the reforming method in this reforming apparatus 12 is not limited to the example of the aforementioned method for reforming water vapor and carbon dioxide gas. For example, a steam reforming method, a partial oxidation method (POC) using oxygen, an autothermal reforming method (ATR), which is a combination of a partial oxidation method and a steam reforming method, a carbon dioxide gas reforming method, and the like can also be used.

CH ₄ + H ₂ O → CO + 3H ₂ ... (1)

CH ₄ + CO ₂ → 2CO + 2H ₂ ... (2)

Further, a device for separating hydrogen 26 is provided in a line branching off from the main pipeline that connects the CO ₂ removal unit 20 or a gas-liquid separator 18 to a bubble column reactor 30. This hydrogen separating device 26 may be constituted, for example, by a hydrogen adsorption device at variable pressure (PSA), which produces adsorption and desorption of hydrogen using a pressure differential. This variable pressure hydrogen adsorption (PSA) device has adsorbents (zeolite adsorbent, activated carbon, alumina, silica gel, etc.) inside a plurality of absorption columns (not shown) that are arranged in parallel. By sequentially repeating processes, including compression, adsorption, desorption (during depressurization) and purging of hydrogen in each of the absorption columns, high-purity (for example, with a purity of about 99.999%) hydrogen gas separated from the synthesis gas can be continuously fed into the reactor.

In addition, the method for separating hydrogen gas in the hydrogen separator 26 is not limited to an example of a method for adsorbing hydrogen under alternating pressure, as in the above hydrogen separator (PSA). For example, it may be a method for storing hydrogen by adsorption by alloys, a membrane separation method, or a combination thereof.

For example, a method for storing hydrogen by adsorption by alloys is a technology for separating hydrogen gas using a hydrogen-absorbing alloy (TiFe, LaNi ₅ , TiFe _0.7-0.9 Mn _0.3-0.1 , TiMn _1.5 , etc. .), which has the property of absorbing or releasing hydrogen in a cooled or heated state. By using a plurality of absorption columns containing a hydrogen absorbing alloy and alternately repeating hydrogen adsorption in each of the absorption columns while cooling the hydrogen absorbing alloy and releasing hydrogen by heating the hydrogen absorbing alloy, hydrogen gas in the synthesis gas can be separated and disposed of.

Further, the membrane separation method is a hydrogen gas separation technology having the ability to perfectly diffuse through a membrane from a gas mixture using a membrane made of a polymeric material such as aromatic polyimide. Since this method of membrane separation is not accompanied by a change in the phase state, less energy is required for its implementation and the cost of the process is reduced. Further, since the design of the membrane separation device is simple and compact, low production costs are required, and the production space required for installation is also reduced. Moreover, since there is no drive mechanism in the separation membrane and a wide range of conditions for stable operation, there is an advantage in the simplicity of maintenance and control.

Next, FT synthesis block 5 will be described. The FT synthesis unit 5 mainly includes, for example, a bubble column reactor 30, a gas-liquid separator 34, a separator 36, a gas-liquid separator 38 and a first distillation column 40. A bubble column reactor 30 conducts a FT synthesis synthesis gas reaction obtained in the aforementioned apparatus for producing synthesis gas 3, i.e., gaseous carbon monoxide and gaseous hydrogen, with the formation of liquid hydrocarbons. The gas-liquid separator 34 separates the water circulating and heated in the tubular heat exchanger 32 located in the bubble column reactor 30 into steam (medium pressure steam) and liquid. The separator 36 is connected to the Central part of the bubble column reactor 30 and separates the catalyst and the liquid hydrocarbon product. A gas-liquid separator 38 is connected to the top of the bubble column reactor 30 and cools the unreacted synthesis gas and gaseous hydrocarbon product. The first distillation column 40 accelerates the liquid hydrocarbons entering through the separator 36 and the gas-liquid separator 38 from the bubble column reactor 30, and separates and refines the liquid hydrocarbons into individual product fractions according to boiling points.

Among them, the bubble column reactor 30, which is an example of a reactor that converts synthesis gas to liquid hydrocarbons, functions as a reactor that produces liquid hydrocarbons from synthesis gas by a FT synthesis reaction. This bubble column reactor 30 is constituted, for example, by a suspension bubble column reactor in which a suspension consisting of a catalyst and an oil medium is placed inside the column. This bubble column reactor 30 produces liquid hydrocarbons from synthesis gas using a FT synthesis reaction. In more detail, in this bubble column reactor 30, synthesis gas as feed gas is supplied by bubbling through a perforated plate divider in the bottom of the bubble column reactor 30 and passes through a suspension consisting of a catalyst and an oil medium, and in a suspended state, hydrogen gas and gaseous carbon monoxide synthesize with the catalyst, as shown in the following chemical reaction equation (3).

2nH ₂ + nCO → (-CH ₂ -) _n + nH ₂ O ... (3)

Since this FT synthesis reaction is an exothermic reaction, the bubble column reactor 30, which is a heat exchanger type reactor inside which a tubular heat exchanger 32 is placed, is arranged such that, for example, water (BFW: water for feeding the boiler) is supplied as a cooling medium so that the heat of reaction from the aforementioned FT synthesis reaction can be disposed of as medium pressure vapor by heat exchange between the suspension and water.

Finally, a quality improvement unit 7 will be described. The quality improvement unit 7 includes, for example, a wax component hydrocracking reactor 50, a kerosene and gas oil fraction hydrogenation reactor 52, a naphtha hydrogenation reactor 54, gas-liquid separators 56, 58 and 60, a second distillation column 70, and a naphtha stabilizer 72. The wax component hydrocracking reactor 50 is connected to the lower part of the first distillation column 40. The kerosene and gas oil fraction hydrogenation reactor 52 is connected to the central part of the first distillation column 40. The naphtha hydrogenation reactor 54 is connected to the upper part of the first distillation column 40. Gas-liquid separators 56, 58 and 60 are arranged to correspond to hydrogenation reactors 50, 52, and 54, respectively. A second distillation column 70 separates and purifies the liquid hydrocarbons from the gas-liquid separators 56 and 58 according to the boiling points. The naphtha stabilizer 72 rectifies the liquid hydrocarbons of the naphtha fraction coming from the gas-liquid separator 60 and the second distillation column 70. The naphtha stabilizer 72 then removes components that are lighter than butane in the form of gas flared and separates and regenerates components having a number carbon atoms of five and above, as a ligroin product.

Next, a process (GTL process) for synthesizing liquid fuel from natural gas using the liquid fuel synthesis system 1 configured as shown above will be described.

Natural gas (the main component of which is CH ₄ ) as a hydrocarbon feed is supplied to the liquid fuel synthesis system 1 from an external source of natural gas (not shown), such as a natural gas field or a natural gas processing plant. The above synthesis gas production unit 3 converts this natural gas to produce synthesis gas (a gas mixture comprising carbon monoxide gas and hydrogen gas as main components).

More specifically, firstly, the aforementioned natural gas is supplied to the desulfurization reactor 10 together with hydrogen gas separated in the hydrogen separation device 26. The desulfurization reactor 10 hydrogenates and desulfurizes the sulfur component present in the natural gas using hydrogen gas using ZnO catalyst. Due to the preliminary desulfurization of natural gas in this way, it is possible to prevent the sulfur-induced decrease in the activity of the catalyst used in the reforming apparatus 12, the bubble column reactor 30, etc.

Natural gas (may also contain carbon dioxide), subjected to desulfurization by this method, is fed to the reforming apparatus 12, after which gaseous carbon dioxide (CO ₂ ) supplied from a carbon dioxide supply source (not shown), and water vapor formed in the boiler 14, using the heat of the exhaust gases, mixed with desulphurized natural gas. The reforming apparatus 12 converts natural gas using carbon dioxide and steam to form a high-temperature synthesis gas including carbon monoxide gas and hydrogen gas as main components using the aforementioned method for reforming water vapor and carbon dioxide gas. At this time, the reforming apparatus 12 is supplied with, for example, gaseous fuel for the burner located in the reforming apparatus 12, and air, and the heat of reaction required for the aforementioned reforming reaction of water vapor and gaseous carbon dioxide, which is an endothermic reaction, is supplied from heat combustion of gaseous fuel in the burner.

High-temperature synthesis gas (for example, with a temperature of 900 ° C, a pressure of 2.0 MPa (excess)) obtained in the reforming apparatus 12 in this way is fed to a boiler 14 using exhaust gas heat and cooled by heat exchange with water, which circulates through the boiler 14, using the heat of the exhaust gases (for example, to a temperature of 400 ° C), thereby losing and utilizing heat. At this point, the water heated by the synthesis gas in the boiler 14 using the heat of the exhaust gases is supplied to the gas-liquid separator 16. From this gas-liquid separator 16, the gaseous component is supplied to the reforming apparatus 12 or other external devices in the form of high pressure steam (for example, pressure from 3.4 to 10.0 MPa (excess)), and water in the form of a liquid component is returned to the boiler 14 using the heat of the exhaust gases.

Meanwhile, the synthesis gas cooled in the boiler 14, using the heat of the exhaust gases, is supplied to the absorption column 22 of the block 20 to remove CO ₂ or bubble column reactor 30, after the condensed components are separated and removed from the synthesis gas in a gas-liquid separator 18. The absorption column 22 absorbs the carbon dioxide gas present in the synthesis gas using a circulating absorber to remove carbon dioxide gas from the synthesis gas. The absorber trapping carbon dioxide gas inside this absorption column 22 is introduced into the regeneration column 24, the absorber comprising carbon dioxide gas is heated and subjected to desorption treatment, for example, with steam, and the resulting free carbon dioxide gas is fed to the reforming apparatus 12 from the regeneration column 24 and is used again for the aforementioned reforming reaction.

The synthesis gas obtained in this way in block 3 for producing synthesis gas is supplied to the bubble column reactor 30 of the above FT synthesis block 5. At this time, the compositional ratio of the synthesis gas fed to the bubble column reactor 30 is adjusted to the compositional ratio (e.g., H ₂ : CO = 2: 1 (molar ratio)) suitable for the FT synthesis reaction. In addition, the pressure of the synthesis gas supplied to the bubble column reactor 30 is increased to a pressure (e.g., 3.6 MPa (excess)) suitable for the FT synthesis reaction using a compressor (not shown) provided in the pipeline, which connects the block 20 to remove CO ₂ with a bubble column reactor 30.

Further, part of the synthesis gas from which carbon dioxide gas has been separated in the said unit 20 for removing CO _2, is also fed to the hydrogen separation device 26. The hydrogen separating apparatus 26 separates the hydrogen gas present in the synthesis gas, by adsorption and desorption (hydrogen adsorption at variable pressure (PSA)) using the pressure difference, as described above. This separated hydrogen is continuously supplied from a gas tank (not shown) and the like. through a compressor (not shown) to a variety of hydrogen-using reaction devices (e.g., desulphurization reactor 10, wax component hydrocracking reactor 50, kerosene and gas oil fraction hydrogenation reactor 52, naphtha hydrogenation reactor 54, etc.) that perform predetermined reactions, using hydrogen within the framework of the liquid fuel synthesis system 1.

Further, the above FT synthesis unit 5 produces liquid hydrocarbons by the FT synthesis reaction from synthesis gas obtained in the above synthesis gas production unit 3.

More specifically, synthesis gas from which carbon dioxide gas was separated in the aforementioned unit 20 for removing CO ₂ flows into the bubble column reactor 30 from the bottom of the reactor 30 and flows through a catalyst slurry placed in the bubble column reactor 30. At this time inside the bubble column reactor 30, carbon monoxide and hydrogen gas, which are part of the synthesis gas, react with each other in the FT synthesis reaction, thereby forming hydrocarbons. Moreover, by circulating water through a tubular heat exchanger 32 in a bubble column reactor 30 during this synthesis reaction, the heat of the FT synthesis reaction is removed and the water heated by this heat exchange evaporates to form steam. As for this water vapor, the water separated in the gas-liquid separator 34 is returned to the tubular heat exchanger 32, and the steam is supplied to the external device in the form of medium pressure steam (for example, with a pressure of from 1.0 to 2.5 MPa (excess)).

The liquid hydrocarbons synthesized in the bubble column reactor 30 in this way are removed from the central portion of the bubble column reactor 30 and introduced into the separator 36. The separator 36 separates the introduced liquid hydrocarbons into a catalyst (solid component) in the recovered suspension and a liquid component including a liquid hydrocarbon product. A portion of the separated catalyst is fed to a bubble column reactor 30, and a liquid component is supplied from it to a first distillation column 40. From the top of the bubble column reactor 30, unreacted synthesis gas and a gaseous component of the synthesized hydrocarbons are introduced into a gas-liquid separator 38. A gas-liquid separator 38 cools these gases and then separates some of the condensed liquid hydrocarbons for introduction into the first distillation column 40. Meanwhile, in the form of a gaseous component, the department Nogo in the gas-liquid separator 38, unreacted synthesis gases (CO and H ₂₎ are introduced into the bottom of the bubble column reactor 30 and used again for the FT synthesis reaction. Further, a gaseous discharge (gas for flaring), other than the target products, which contains as a main component a gaseous hydrocarbon having a low number of carbon atoms (C ₄ or less), is output to an external combustion device (not shown), burned in it and then released into the atmosphere.

Further, the first distillation column 40 heats the liquid hydrocarbons (the number of carbon atoms in which) is supplied through a separator 36 and a gas-liquid separator 38 from the bubble column reactor 30, as described above, for fractional distillation of liquid hydrocarbons using the difference in boiling points. Thus, the first distillation column 40 separates and purifies liquid hydrocarbons into a naphtha fraction (boiling point of which is less than about 315 ° C), a kerosene and gas oil fraction (boiling point of which is from about 315 to 800 ° C) and a wax component (boiling point which is more than about 800 ° C). Liquid hydrocarbons (mainly C ₂₁ or more), as a wax component, extracted from the bottom of the first distillation column 40, are transferred to the wax component hydrocracking reactor 50, liquid hydrocarbons (mainly C ₁₁ to C ₂₀ ), as a kerosene and gas oil fraction removed from the central part of the first distillation column 40 are transferred to the hydrogenation reactor 52 of the kerosene and gas oil fraction, and liquid hydrocarbons (mainly from C ₅ to C ₁₀ ), as a naphtha fraction recovered from the upper part of the first rect identification columns 40 are transferred to the ligroin fraction hydrogenation reactor 54.

The wax component hydrocracking reactor 50 hydrocracks liquid hydrocarbons as a wax component with a high number of carbon atoms (approximately C ₂₁ or more) that was fed from the bottom of the first distillation column 40 using hydrogen gas supplied from the aforementioned hydrogen separation device 26 to reduce the number of carbon atoms to less than C ₂₀ . In this hydrocracking reaction, hydrocarbons with a high number of carbon atoms and low molecular weight are formed by cleavage of C — C bonds in hydrocarbons with a large number of carbon atoms, using a catalyst and heat. A product including liquid hydrocarbons obtained by hydrocracking in this wax component hydrocracking reactor 50 is separated into gas and liquid in a gas-liquid separator 56, from which liquid hydrocarbons are sent to a second distillation column 70, and a gaseous component (including hydrogen gas) is sent to the reactor 52 hydrogenation of the kerosene and gas oil fraction; and a naphtha hydrogenation reactor 54.

The kerosene and gas oil fraction hydrogenation reactor 52 hydrogenates liquid hydrocarbons (approximately C ₁₁ to C ₂₀ ) as a kerosene and gas oil fraction having approximately the average number of carbon atoms that was supplied from the central portion of the first distillation column 40 using hydrogen gas, fed through the hydrocracking reactor 50 of the wax component from the hydrogen separation device 26. This hydrogenation reaction is a reaction in which hydrogen is attached to saturated relations above liquid hydrocarbons to saturate the liquid hydrocarbons and the formation of saturated hydrocarbons with a linear chain. As a result, a product including hydrogenated liquid hydrocarbons is separated into gas and liquid in a gas-liquid separator 58, from which liquid hydrocarbons are sent to a second distillation column 70, and the gaseous component (including hydrogen gas) of which is used again for the above hydrogenation reaction.

The naphtha hydrogenation reactor 54 hydrogenates liquid hydrocarbons (approximately C ₁₀ or less) as a low carbon atom naphtha fraction which was fed from the top of the first distillation column 40 using hydrogen gas supplied through a wax component hydrocracking reactor 50 from hydrogen separation devices 26. As a result, the product, including hydrogenated liquid hydrocarbons, is separated into gas and liquid in a gas-liquid separator 60, liquid carbohydrates the hydrogen species from which are transferred to the naphtha stabilizer 72 and the gaseous component (including hydrogen gas) which is used again for the aforementioned hydrogenation reaction.

Further, the second distillation column 70 accelerates liquid hydrocarbons supplied from the wax component hydrocracking reactor 50 and the kerosene and gas oil fraction hydrogenation reactor 52, as described above. Thus, the second distillation column 70 separates and purifies liquid hydrocarbons into a naphtha fraction (boiling point of which is less than about 315 ° C) with 10 carbon atoms or less, kerosene (boiling point of which is from about 315 to 450 ° C) and gas oil (boiling point of which is from about 450 to 800 ° C). Gas oil is removed from the bottom of the second distillation column 70, and kerosene is taken from the central part thereof. Meanwhile, a gaseous hydrocarbon with a number of carbon atoms of 10 or more is recovered from the upper part of the second distillation column 70 and fed to a naphtha stabilizer 72.

Moreover, the naphtha stabilizer 72 accelerates hydrocarbons with a carbon number of 10 or less that were supplied from the aforementioned ligroin fraction hydrogenation reactor 54 and the second distillation column 70. Thus, the naphtha stabilizer 72 separates and refines the naphtha (C ₅ to C ₁₀ ) as product. Accordingly, high-purity naphtha is extracted from the bottom of the naphtha stabilizer 72. Meanwhile, the exhaust gas (exhaust gas), other than products, which contains hydrocarbons with the number of carbon atoms less than or equal to a predetermined or smaller number (less than or equal to C ₄ ) as the main component, is discharged from the upper part of the stabilizer 72 naphthas. Although typically this off-gas is fed to an external incinerator (not shown), burned as a flare gas and then released into the atmosphere as a gaseous discharge, the liquid fuel synthesis system according to the present embodiment has the peculiarity of utilizing hydrocarbons with a number of atoms four or less carbon contained in this off-gas using methods as described in detail below, and reuses hydrocarbons as part of the raw material.

So far, the process (GTL process) of the liquid fuel synthesis system 1 has been described. Using the GTL process, natural gas can be easily and economically converted to pure liquid fuels, such as highly pure naphtha (C ₅ to C ₁₀ : untreated gasoline), kerosene (C ₁₁ to C ₁₅ : kerosene) and gas oil (C ₁₆ to C ₂₀ : gas oil). Moreover, in the present embodiment, the aforementioned method for reforming water vapor and gaseous carbon dioxide is performed in the reforming apparatus 12. Thus, there are advantages in which carbon dioxide contained in the natural gas used as a raw material can be disposed of efficiently. a compositional ratio (for example, H ₂ : CO = 2: 1 (molar ratio)) of the synthesis gas suitable for the above FT synthesis reaction can be effectively implemented in a single reaction in a reforming apparatus 12 , adjusting the concentration of hydrogen, etc. not necessary.

Next, referring to FIGS. 2-4, a feeding device that supplies hydrocarbons with four or less carbon atoms contained in the exhaust gas discharged from the upper part of the naphtha stabilizer as part of the raw material of the liquid fuel synthesis system 1 will be described in detail. according to the present embodiment.

FIG. 2 is a flowchart for explaining a feed device that supplies exhaust gas discharged from an upper portion of a naphtha stabilizer 72 to an installation upstream of a naphtha stabilizer 72 in a liquid fuel synthesis system 1 according to the present embodiment. In addition, in FIG. 2, for convenience of description, the main components of the liquid fuel synthesis system 1 of FIG. 1 are illustrated, an illustration of some of the components is omitted.

As described above, hydrocarbons with four or less carbon atoms are contained in the exhaust gas discharged from the top of the naphtha stabilizer. Although these hydrocarbons with four or less carbon atoms differ from the target products, they are available as hydrocarbon feed to the first reformer 12.

As shown in FIG. 2, in an exemplary arrangement according to the present embodiment, one end of the off-gas extraction and supply path 100 is connected to the top of the head of the naphtha stabilizer 72, and the other end of the off-gas extraction and supply path 100 is connected to the upstream side reforming apparatus 12. With this route 100 hydrocarbons with four or less carbon atoms contained in the exhaust gas can be reused as part of the hydrocarbon feed material for introduction into forming apparatus 12.

Using the aforementioned exhaust gas recovery and supply route 100, the amount of natural gas used can be reduced from a natural gas supply source (not shown) located upstream of the reforming apparatus 12. Therefore, the efficiency of using hydrocarbon raw material in the whole can be improved. liquid fuel synthesis system as a whole.

In addition, at the connection point between the exhaust gas extraction and supply route 100 and the main route that natural gas is supplied to, both routes can be interconnected via a control valve (not shown) or the like, so that the amount of natural gas supplied can be controlled according to pressure, flow rate, etc. off-gas, which is present in route 100.

FIG. 3 is a block diagram for explaining yet another exemplary arrangement that supplies off-gas from the top of a naphtha stabilizer 72 to a plant located upstream of the naphtha stabilizer 72 in the liquid fuel synthesis system 1 according to the present embodiment. In addition, also in FIG. 3, for convenience of description, the main components of the liquid fuel synthesis system 1 of FIG. 1 are illustrated, an illustration of some components is omitted.

In this exemplary arrangement, the exhaust gas discharged from the upper part of the naphtha stabilizer 72 is introduced into the second reforming apparatus 102 (hereinafter referred to as the “reforming apparatus 102”), which is located separately from the reforming apparatus 12, and is subjected to reforming therein, thereby forming synthesis gas containing gaseous carbon monoxide and gaseous hydrogen as the main components. The carbon dioxide needed to convert the exhaust gas may be supplied from a carbon dioxide supply source (not shown), which is located separately, or may be supplied from a carbon dioxide supply source (not shown), which supplies carbon dioxide to the reforming apparatus 12, or off-gas can only be reformed with water vapor.

The synthesis gas synthesized in the aforementioned reforming apparatus 102 is supplied to the bubble column reactor 30 from the upstream side through a synthesis gas supply conduit 104 connected to the reforming apparatus 102 and is used as part of the raw material for FT synthesis reactions, etc. As described above, when reforming the exhaust gas discharged from the top to use the exhaust gas as synthesis gas, the efficiency of using natural gas in the entire liquid fuel synthesis system as a whole can be improved.

In addition, when the amount of synthesis gas produced in the reforming apparatus 12 and the reforming apparatus 102 can be monitored, and the amount of synthesis gas sufficient for the reaction, is obtained in the reforming apparatus 102, the amount of natural gas supplied from the natural gas supply source gas (not shown) can also be reduced by reducing the amount of synthesis gas obtained in the reforming apparatus 12.

FIG. 4 is a flowchart for explaining yet another exemplary arrangement that supplies exhaust gas discharged from the top of a naphtha stabilizer 72 to an apparatus located upstream of the naphtha stabilizer 72 in a liquid fuel synthesis system according to the present embodiment . In addition, also in FIG. 4, for convenience of description, the main components of the liquid fuel synthesis system 1 of FIG. 1 are illustrated, an illustration of some of the components is omitted.

The exemplary arrangement illustrated in FIG. 4 mainly includes a reforming apparatus 102 that performs the reforming of the exhaust gas discharged from the top of the naphtha stabilizer 72, a hydrogen separation device 106 that separates the synthesis gas, which contains gaseous carbon monoxide and gaseous hydrogen as the main components formed in the reforming apparatus 102, to gaseous carbon monoxide and gaseous hydrogen, and a hydrogen storage device 110 that stores hydrogen gas, flushed in a hydrogen separation device 106.

Since the reforming apparatus 102 has the same functional purpose and acts the same as shown in FIG. 3, a detailed description thereof is omitted. The hydrogen separation device 106 is an apparatus that separates the synthesis gas obtained in the reforming apparatus 102 into gaseous carbon monoxide and gaseous hydrogen. A carbon monoxide gas supply line 108 that leads the separated carbon monoxide gas to the bubble column reactor 30 from the upstream side and a hydrogen storage device 110 that can store the separated hydrogen gas are connected to the hydrogen separation device 106. As the aforementioned hydrogen separation device 106, an apparatus that has the same functionality and functions in the same way as the hydrogen separation device 26 located in the synthesis gas production unit 3 can be used.

In addition, a separate supply route may be provided so that the synthesis gas synthesized in the reforming apparatus 102 can be brought directly to a place upstream of the reforming apparatus 12.

The carbon monoxide supply path 108 delivers gaseous carbon monoxide separated in a hydrogen separation device 106, for example, to adjust the concentration of carbon monoxide in the synthesis gas supplied to the bubble column reactor 30. That is, when the concentration of carbon monoxide in the synthesis gas is monitored generated in the reforming apparatus 12 and the amount of carbon monoxide supplied through the gaseous carbon monoxide supply path 108 is small, the gaseous carbon monoxide may be odveden to the reformer unit 12 to route 108 the gaseous carbon monoxide through the apparatus for storage of carbon monoxide and carbon monoxide compressor (not shown) provided in the path 108 supplying gaseous carbon monoxide.

The hydrogen storage device 110, for example, consists of a storage tank consisting of pressurized airtight containers, such as a spherical tank, and can, for example, store hydrogen gas separated in the hydrogen separation device 106 in a liquefied state. A hydrogen gas supply route 112 is connected to this hydrogen storage device 110.

The hydrogen gas supply route 112 can supply hydrogen gas to all places where hydrogen gas is required in the liquid fuel synthesis system 1 according to the present embodiment, thereby properly adjusting the hydrogen gas concentration. Places where hydrogen gas is required include, for example, a desulfurization reactor 10, which hydrogenates and desulfurizes natural gas as a hydrocarbon feed, a bubble column reactor 30, which synthesizes a plurality of liquid fuels having different boiling points from synthesis gas, containing gaseous carbon monoxide and gaseous hydrogen as the main components, or reactors 50, 52 and 54 for hydrogenation, which produce hydrogenation of liquid fuel having unsaturated carbon-carbon bonds, such as double C = C bonds or triple C≡C bonds.

Compared with the conventional liquid fuel synthesis system in the liquid fuel synthesis system 1, according to the present embodiment, it is possible to reduce the amount of natural gas used as a raw material by about 10-15% or more in the whole system using a feed device as described above.

In addition, with the hydrogen storage device 110, hydrogen gas can be supplied immediately from the hydrogen storage device 110 when hydrogen gas is required. For this reason, hydrogen gas stored in the hydrogen storage device 110 can be immediately supplied to hydrogen-using reaction devices, such as hydrogenation reactors 50, 52 and 54 or a desulfurization reactor 10, during restart, etc. systems 1 synthesis of liquid fuel. In this way, the period of time taken to start up and bring these hydrogen-using reaction devices to a stable state can be minimized. Accordingly, since the heating time of the entire liquid fuel synthesis system 1 as a whole can be significantly reduced, the production efficiency of liquid fuel products such as naphtha, kerosene, gas oil and wax can be improved.

Although 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 will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the claims, and it will be understood that these changes or modifications naturally belong to the technical field of the present invention.

For example, in the above embodiments, natural gas is used as the hydrocarbon feed material supplied to the liquid fuel synthesis system 1. However, the present invention is not limited to such an example. For example, other hydrocarbon feedstocks such as bitumen and heating oil can be used.

Further, in the above embodiment, a case has been described where the liquid fuel synthesis system 1 is equipped with a unit 20 for removing CO ₂ . However, depending on the circumstances, block 20 for the removal of CO ₂ may be absent.

Further, in the above embodiment, liquid hydrocarbons are synthesized by FT synthesis reaction as a synthesis reaction in a bubble column reactor 30. However, the present invention is not limited to this example. More specifically, the present invention can be applied, for example, to oxosynthesis (hydroformylation reaction) R-CH = CH ₂ + CO + H ₂ → R-CH ₂ CH ₂ CHO, methanol synthesis CO + 2H ₂ → CH ₃ OH, dimethyl synthesis ether (DME, DME) 3CO + 3H ₂ → CH ₃ OCH ₃ + CO ₂ , etc., as a synthetic reaction in a bubble column reactor.

Further, in the above embodiment, the desulfurization reactor 10, the wax component hydrocracking reactor 50, the kerosene and gas oil fraction hydrogenation reactor 52, and the naphtha hydrogenation reactor 54 are shown as examples of hydrogen-using reaction devices. However, the present invention is not limited to such examples. Any plants other than those mentioned above can be involved to the extent that they perform a given reaction using hydrogen gas in a liquid fuel synthesis system. More specifically, a hydrogen-using reaction device can be, for example, a fuel cell, a plant in which a hydrogenation reaction (naphthalene → decalin) of naphthalene is carried out, a plant that performs a hydrogenation reaction (benzene → cyclohexane, etc.) of aromatic hydrocarbons (benzene ), or a plant that conducts the hydrogenation reaction of an unsaturated aliphatic acid.

Further, in the above embodiments, a slurry bubble column reactor is used as a reactor that converts synthesis gas to liquid hydrocarbons. However, the present invention is not limited to such an example. For example, a FT synthesis reaction may be carried out using a type of fixed bed reactor, etc.

Further, although the above embodiment has been described using, as an example, exhaust gas discharged from the top of the naphtha stabilizer, the present invention is not limited to the gas discharged from the top of the naphtha stabilizer. For example, it is also possible to carry out the above-described treatment of gases discharged from the upper parts of other distillation columns and gas discharged from a gas-liquid separator.

INDUSTRIAL APPLICABILITY

The present invention relates to a liquid fuel synthesis system comprising a first reforming apparatus that converts a hydrocarbon feed material to produce synthesis gas comprising carbon monoxide gas and hydrogen gas as main components; a reactor that synthesizes liquid hydrocarbons from gaseous carbon monoxide and gaseous hydrogen contained in the synthesis gas; the first distillation column, which heats the liquid hydrocarbons synthesized in the reactor, for fractional distillation of many varieties of liquid fuels having different boiling points; a hydrogen using a reaction device that performs a given reaction with a hydrocarbon feed or liquid fuels using hydrogen gas contained in the synthesis gas; a second distillation column that purifies the liquid component separated and separated from the hydrogen-using reaction device; and a feed device that delivers gas discharged from the second distillation column to at least one unit from a first reforming apparatus using hydrogen of the reaction device and the reactor as part of the raw material.

Accordingly, the liquid fuel synthesis system according to the present invention, the raw material utilization efficiency can be improved, and the amount of carbon dioxide emissions can be reduced.

Claims (4)

1. A liquid fuel synthesis system comprising:
a first reforming apparatus that converts a hydrocarbon feed material to produce synthesis gas containing carbon monoxide gas and hydrogen gas as main components;
a reactor that synthesizes liquid hydrocarbons from gaseous carbon monoxide and gaseous hydrogen contained in the synthesis gas;
the first distillation column, which heats the liquid hydrocarbons synthesized in the reactor, for fractional distillation of many types of liquid fuel fractions having different boiling points;
hydrogen-using reaction devices that carry out a given reaction with liquid fuel fractions using hydrogen gas contained in the synthesis gas;
a second distillation column, which purifies at least two liquid components separated and isolated from hydrogen-using reaction devices to obtain many types of liquid fuels and gas fractions;
a naphtha stabilizer into which a fraction of the gas withdrawn from the second distillation column is located, located downstream of the second distillation column,
the second reforming apparatus, which performs the reforming of gas discharged from the naphtha stabilizer; and
a device for separating hydrogen, which separates the hydrogen gas from the synthesis gas obtained in the second reforming apparatus, while the gas is removed from the naphtha stabilizer and is piped to the first reforming apparatus or the second reforming apparatus,
the synthesis gas discharged from the second reforming apparatus is piped to a reactor or apparatus for separating hydrogen, and
hydrogen gas separated by a hydrogen separation device is piped to a reactor or reaction devices using hydrogen. 2. The liquid fuel synthesis system according to claim 1, wherein the hydrogen-using reaction device comprises a hydrogenation reactor that hydrogenates at least one of a plurality of types of liquid fuels and / or a desulfurization reactor that hydrogenates and desulfurizes the hydrocarbon feed to the first reforming apparatus. 3. The liquid fuel synthesis system of claim 1, further comprising a hydrogen storage device that stores hydrogen gas separated by a hydrogen separation device. 4. The liquid fuel synthesis system according to claim 3, wherein the feed device delivers hydrogen gas stored in the hydrogen storage device to the hydrogen-using reaction devices during start-up of the liquid fuel synthesis system.

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