Fuel production method, and fuel production system

Abstract

To provide a fuel production method and a fuel production system improving energy efficiency and decreasing a load to the environment.SOLUTION: The method of producing fuel from a biomass raw material comprises a synthesis gas production step of reacting a biomass raw material, hydrogen, water, and carbon dioxide to produce synthesis gas including hydrogen and carbon monoxide, and a Fischer-Tropsch synthesis step of subjecting the synthesis gas to a Fischer-Tropsch synthesis reaction and separating FT off-gas including hydrogen to produce Fischer-Tropsch oil, with hydrogen supplied to the synthesis gas production step including hydrogen present in the FT off-gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fuel production method and a fuel production system. [Background technology]

[0002] Efforts aimed at mitigating or reducing the impact of climate change have been ongoing for some time, and research and development into reducing carbon dioxide emissions is being carried out to achieve this. In recent years, synthetic fuels made from hydrogen generated from electricity generated by renewable energy sources and carbon sources such as biomass and carbon dioxide emitted from factories have been attracting attention as an alternative to fossil fuels.

[0003] The general procedure for producing liquid fuels such as methanol and gasoline using biomass as a feedstock is as follows: A liquid fuel is produced from biomass feedstock through the following steps: a gasification process in which biomass feedstock that has undergone a specified pretreatment is gasified together with water and oxygen in a gasifier to produce a synthesis gas containing hydrogen and carbon monoxide; a cleaning process in which the synthesis gas produced is cleaned and tar is removed; an H2 / CO ratio adjustment process in which the H2 / CO ratio of the synthesis gas that has undergone the cleaning process is adjusted to a target ratio appropriate for the liquid fuel to be produced; a desulfurization process in which sulfur components are removed from the synthesis gas that has undergone the H2 / CO ratio adjustment process; and a fuel production process in which liquid fuel is produced from the synthesis gas that has undergone the desulfurization process.

[0004] The H2 / CO ratio of the synthesis gas produced through the gasification process often does not reach the target ratio, resulting in a hydrogen deficiency. For this reason, by supplying steam during the gasification process, it is possible to increase the H2 / CO ratio to closer to 2.0, which is the preferred ratio for the Fischer-Tropsch synthesis reaction (hereinafter also referred to as the FT synthesis reaction).

[0005] The target products of the FT synthesis reaction, hydrocarbons with a high carbon number and high boiling point, are extracted as liquid components (hereinafter also referred to as Fischer-Tropsch oil). However, the carbon dioxide contained in the synthesis gas, the reaction by-products HO, light hydrocarbons such as methane and ethane, and unreacted hydrogen and carbon monoxide are extracted as a mixed gaseous component and removed as off-gas (hereinafter also referred to as FT off-gas). However, since FT off-gas contains hydrogen, which is the raw material for the FT synthesis reaction, using it as fuel is energy inefficient.

[0006] Patent Document 1 proposes a method for producing various hydrocarbon oils from natural gas, which includes a step of recycling FT off-gas as fuel for heating a gasification furnace. According to the production method of Patent Document 1, the FT off-gas can be recycled. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-214528 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the production method of Patent Document 1, hydrogen in the FT off-gas is used as fuel for heating the gasification furnace, so hydrogen as a raw material for the FT synthesis reaction is consumed as fuel, and the hydrogen cannot be used effectively, which is a problem. In addition, because the amount of hydrogen supplied in the synthesis gas production process remains the same as before, it is necessary to supply water vapor in addition to hydrogen as before. As a result, the energy consumption required to produce high-purity, high-pressure hydrogen and water vapor is large, resulting in poor energy efficiency. Furthermore, in reducing carbon dioxide emissions, simply recycling the FT off-gas into the FT synthesis reaction does not consume the carbon dioxide in the FT off-gas, and its concentration continues to rise. At some point, this carbon dioxide must be released, which poses a significant environmental burden. In order to solve the above problems, the present application aims to provide a fuel production method and a fuel production system that can effectively utilize hydrogen, improve energy efficiency, and reduce the burden on the environment, thereby contributing to mitigating or reducing the impact of climate change. [Means for solving the problem]

[0009] [1] A method for producing fuel from biomass feedstock, comprising: a synthesis gas production step of reacting a biomass feedstock, hydrogen, water, and carbon dioxide to produce a synthesis gas containing hydrogen and carbon monoxide; a Fischer-Tropsch synthesis step of producing a Fischer-Tropsch oil by subjecting the synthesis gas to a Fischer-Tropsch synthesis reaction and then separating an FT off-gas containing hydrogen, A fuel production method, wherein the hydrogen supplied to the synthesis gas production step comprises hydrogen in the FT off-gas.

[0010] In the fuel production method of the present invention, hydrogen in the FT off-gas is supplied to the synthesis gas production step, thereby making it possible to effectively utilize hydrogen as a raw material for synthesis gas production. Furthermore, because the hydrogen supply volume increases, sufficient amounts of synthesis gas can be produced even when the supply volumes of high-purity, high-pressure hydrogen and steam are reduced, which reduces the energy consumption required to produce high-purity, high-pressure hydrogen and steam, improving energy efficiency. Furthermore, as the supply of hydrogen increases, reactions that consume carbon dioxide as a raw material also proceed more easily, which reduces carbon dioxide emissions and the burden on the environment.

[0011] [2] The fuel production method according to [1], which does not include a heavy hydrocarbon removal step for removing hydrocarbons having a carbon number of 5 or more contained in the FT off-gas.

[0012] The fuel production method of the present invention does not include a heavy hydrocarbon removal step, and therefore the number of steps can be reduced, thereby reducing energy consumption and further improving energy efficiency.

[0013] [3] The fuel production method according to [1], further comprising a hydrogen supplying step of supplying hydrogen in the FT off-gas to the synthesis gas production step.

[0014] In the fuel production method of the present invention, hydrogen in the FT off-gas is supplied to the synthesis gas production step, thereby making it possible to more effectively utilize hydrogen as a raw material for synthesis gas production. Furthermore, because the hydrogen supply can be increased, sufficient amounts of synthesis gas can be produced even when the supply of high-purity, high-pressure hydrogen and steam is reduced. This reduces the energy consumption required to produce high-purity, high-pressure hydrogen and steam, further improving energy efficiency. Furthermore, since the amount of hydrogen supplied can be increased, the reaction that consumes carbon dioxide also proceeds more easily, which reduces carbon dioxide emissions and further reduces the burden on the environment.

[0015] [4] The fuel production method according to [1], wherein only hydrogen in the FT off-gas is supplied as the hydrogen.

[0016] The fuel production method of the present invention allows for more effective use of hydrogen as a raw material for synthesis gas production by supplying only the hydrogen in the FT off-gas to the synthesis gas production step. Furthermore, the amount of hydrogen supplied can be increased without supplying high-purity, high-pressure hydrogen or pressurized hydrogen, which reduces the amount of energy consumed to produce high-purity, high-pressure hydrogen or pressurized hydrogen, thereby further improving energy efficiency.

[0017] [5] The fuel production method according to [1], further comprising a gas separation step of separating the FT off-gas into a gasification assisting gas containing hydrogen and a heat source gas containing hydrocarbons.

[0018] The fuel production method of the present invention can increase the amount of hydrogen supplied by supplying a hydrogen-containing gasification assisting gas to the synthesis gas production process. In addition, the hydrocarbon-containing heat source gas can be recycled as fuel for heating the gasification furnace used in the synthesis gas production process, thereby further improving energy efficiency and further reducing the burden on the environment.

[0019] [6] The fuel production method according to [5], further comprising a heat source gas supplying step of supplying the heat source gas as a heat source in a synthesis gas production step.

[0020] The fuel production method of the present invention can further improve energy efficiency and reduce the burden on the environment by recycling a heat source gas containing hydrocarbons as fuel for heating a gasification furnace used in a synthesis gas production process.

[0021] [7] The fuel production method according to [1], further comprising a steam supplying step of supplying water as steam in the synthesis gas production step so that the mass ratio expressed as [mass of steam] / [mass of biomass] is less than 1.0.

[0022] The fuel production method of the present invention can produce a sufficient amount of synthesis gas even when the amount of steam supplied is reduced compared to conventional methods, thereby reducing the amount of energy consumed to produce steam and further improving energy efficiency.

[0023] [8] The method for producing a fuel according to [1], wherein the FT off-gas is obtained by a fractionation step (s) of fractionating a liquid fuel after the Fischer-Tropsch synthesis step and after hydrocracking the Fischer-Tropsch oil.

[0024] In the fuel production method of the present invention, when obtaining liquid fuel by fractional distillation, FT off-gas containing hydrogen, carbon monoxide, carbon dioxide, and hydrocarbons is also obtained. By supplying the hydrogen in the obtained FT off-gas to the synthesis gas production process, it becomes easier to more effectively utilize hydrogen as a raw material for synthesis gas production. When the total mass of hydrocarbons produced after the FT synthesis reaction is 10 t or less, it is easier to improve energy efficiency by fractionally distilling the liquid fuel obtained after hydrocracking the Fischer-Tropsch oil. In addition,

[0025] [9] The method for producing a fuel according to [1], wherein the FT off-gas is obtained by a fractionation step (l) of fractionating the Fischer-Tropsch oil after the Fischer-Tropsch synthesis step and before hydrotreating or hydrocracking the Fischer-Tropsch oil.

[0026] In the fuel production method of the present invention, when obtaining liquid fuel by fractional distillation, FT off-gas containing hydrogen, carbon monoxide, carbon dioxide, and hydrocarbons is also obtained. Supplying the hydrogen in the obtained FT off-gas to the synthesis gas production step facilitates more effective use of hydrogen as a raw material for synthesis gas production. When the total mass of hydrocarbons produced after the FT synthesis reaction exceeds 10 tons, fractional distillation of the Fischer-Tropsch oil before hydrorefining or hydrocracking the Fischer-Tropsch oil can improve energy efficiency.

[0027]

[10] A fuel production system for producing fuel from biomass feedstock, comprising: a gasification device that reacts a biomass feedstock, hydrogen, water, and carbon dioxide to produce a synthesis gas containing hydrogen and carbon monoxide; a Fischer-Tropsch unit for producing Fischer-Tropsch oil by subjecting the synthesis gas to a Fischer-Tropsch synthesis reaction and then separating an FT off-gas containing hydrogen; a hydrogen supply device that supplies hydrogen in the FT off-gas to the gasification device.

[0028] The fuel production system of the present invention can effectively utilize hydrogen as a raw material for producing synthesis gas by supplying hydrogen in the FT off-gas to the gasification device. Furthermore, because the hydrogen supply volume increases, sufficient amounts of synthesis gas can be produced even when the supply volumes of high-purity, high-pressure hydrogen and steam are reduced, which reduces the energy consumption required to produce high-purity, high-pressure hydrogen and steam, improving energy efficiency. Furthermore, as the supply of hydrogen increases, the reaction that consumes carbon dioxide also progresses more easily, reducing carbon dioxide emissions and the burden on the environment.

[0029]

[11] The fuel production system according to

[10] , which does not have a heavy hydrocarbon removal device for removing hydrocarbons having a carbon number of 5 or more contained in the FT off-gas.

[0030] The fuel production system of the present invention does not have a heavy hydrocarbon removal device, and therefore can reduce energy consumption and further improve energy efficiency.

[0031]

[12] The fuel production system according to

[10] , wherein the hydrogen supply device is a hydrogen supply device that supplies hydrogen in the FT off-gas to the gasification device.

[0032] The fuel production system of the present invention can more effectively utilize hydrogen as a raw material for producing synthesis gas by supplying only the hydrogen in the FT off-gas to the gasification device. Furthermore, the amount of hydrogen supplied can be increased without supplying high-purity, high-pressure hydrogen or pressurized hydrogen, which reduces the amount of energy consumed to produce high-purity, high-pressure hydrogen or pressurized hydrogen, thereby further improving energy efficiency.

[0033]

[13] The fuel production system according to

[10] , further comprising a gas separation device that separates the FT off-gas into a gasification assist gas containing hydrogen and a heat source gas containing hydrocarbons.

[0034] The fuel production system of the present invention can increase the amount of hydrogen supplied by supplying a hydrogen-containing gasification assisting gas to the gasification apparatus, and can also recycle a hydrocarbon-containing heat source gas as fuel for heating the gasification furnace used in the gasification apparatus, thereby further improving energy efficiency and reducing the burden on the environment.

[0035]

[14] The fuel production system according to

[13] , further comprising a heat source gas supply device for supplying the heat source gas as a heat source in a synthesis gas production process.

[0036] The fuel production system of the present invention can further improve energy efficiency and reduce the burden on the environment by recycling the heat source gas containing hydrocarbons as fuel for heating the gasification furnace used in the gasification device.

[0037]

[15] The fuel production system according to

[10] , further comprising a steam supply device that supplies steam as water to the gasification device so that the mass ratio expressed as [mass of steam] / [mass of biomass] is less than 1.0.

[0038] The fuel production system of the present invention can produce a sufficient amount of synthesis gas even when the amount of steam supplied is reduced compared to conventional methods, which reduces the amount of energy consumed to produce steam and improves energy efficiency.

[0039]

[16] The fuel production system according to claim 10, further comprising a fractionator (S) downstream of the Fischer-Tropsch unit and downstream of the hydrocracker that hydrocracks the Fischer-Tropsch oil, for fractionating a liquid fuel and the FT off-gas.

[0040] In the fuel production system of the present invention, when obtaining liquid fuel by fractional distillation, FT off-gas containing hydrogen, carbon monoxide, carbon dioxide, and hydrocarbons is also obtained. By supplying the hydrogen in the obtained FT off-gas to the gasification system, it becomes easier to more effectively utilize hydrogen as a raw material for producing synthesis gas. When the total mass of hydrocarbons produced after the FT synthesis reaction is 10 tons or less, it is easier to improve energy efficiency by hydrocracking the Fischer-Tropsch oil and then fractionating the obtained liquid fuel.

[0041]

[17] The fuel production system according to

[10] , further comprising a fractionator (L) that fractionates the Fischer-Tropsch oil and the FT off-gas, downstream of the Fischer-Tropsch unit and upstream of a hydrotreating unit that hydrotreates the Fischer-Tropsch oil.

[0042] In the fuel production system of the present invention, when obtaining liquid fuel by fractional distillation, FT off-gas containing hydrogen, carbon monoxide, carbon dioxide, and hydrocarbons is also obtained. By supplying the hydrogen in the obtained FT off-gas to the gasification apparatus, it becomes easier to more effectively utilize hydrogen as a raw material for producing synthesis gas. When the total mass of hydrocarbons produced after the FT synthesis reaction exceeds 10 tons, fractional distillation of the Fischer-Tropsch oil before hydrorefining or hydrocracking the Fischer-Tropsch oil can more easily improve energy efficiency. [Effects of the Invention]

[0043] According to the present invention, it is possible to provide a fuel production method and a fuel production system that can effectively utilize hydrogen, improve energy efficiency, and reduce the burden on the environment, which in turn can contribute to mitigating or reducing the impact of climate change. [Brief explanation of the drawings]

[0044] [Figure 1] 1 is a flowchart showing a configuration of a fuel production method according to one embodiment of the present invention. [Figure 2]10 is a flowchart showing the configuration of a fuel production method according to another embodiment of the present invention. [Figure 3] 1 is a schematic diagram showing the configuration of a fuel production system according to an embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram showing the configuration of a fuel production system according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0045] The present invention will be outlined below. The synthesis gas produced by the reforming reaction of biomass feedstock flows into the bottom of a bubble column reactor installed in the FT unit. The bubble column reactor is filled with a slurry consisting of liquid hydrocarbons, the product of the FT synthesis reaction, and catalyst particles. As the synthesis gas rises within the slurry, hydrocarbons are produced by the FT synthesis reaction with carbon monoxide and hydrogen gas.

[0046] The liquid hydrocarbons synthesized are introduced into a separator as a slurry together with catalyst particles, where they are separated into solid components such as catalyst particles and a liquid component containing liquid hydrocarbons (Fischer-Tropsch oil). The separated solid components are returned to the bubble column reactor. The liquid components are fed to a fractionator, where they are heated and fractionated based on differences in boiling points, and then hydrotreated, or hydrotreated and then fractionated to produce naphtha, SAF (Sustainable Aviation Fuel), diesel, and liquid fuels consisting of heavy fractions.

[0047] Meanwhile, gaseous components (FT off-gas) containing unreacted synthesis gas and gaseous synthesized hydrocarbons are released from the top of the bubble column reactor. The gaseous components are primarily composed of unreacted synthesis gas and light hydrocarbons such as methane and ethane. These gaseous components are subjected to a gas separation device, where they are separated into a gasification assisting gas containing hydrogen, carbon monoxide, and carbon dioxide, and a heat source gas containing hydrocarbons such as methane, ethane, and propane. The gasification assisting gas is resupplied to the gasifier and reused as a raw material for producing synthesis gas. Meanwhile, the heat source gas is reused as fuel for heating the gasification furnace of the gasifier.

[0048] Hereinafter, an embodiment of the method for removing heavy hydrocarbons according to the present invention will be specifically described, although the present invention is not limited to the following embodiment.

[0049] <<Fuel production method>> A fuel production method according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing the configuration of a fuel production method according to this embodiment. In the biomass raw material supply step S2, biomass raw materials such as rice husks, bagasse, and wood are subjected to a predetermined pretreatment, and the pretreated biomass raw materials are supplied via a raw material supply line to a gasification furnace of a gasification apparatus that performs the synthesis gas production step S3. Here, the pretreatment of the biomass raw materials includes, for example, a drying step for drying the raw materials and a crushing step for crushing the raw materials. The method for supplying the biomass raw material to the gasification furnace is not particularly limited, and any known supply method can be used.

[0050] In the synthesis gas production step S3, the biomass raw material, hydrogen, water, and carbon dioxide are reacted to produce a synthesis gas containing hydrocarbons. The reaction conditions for producing the synthesis gas are not particularly limited, and known reaction conditions can be used. When hydrogen, water, and carbon dioxide are introduced into a gasification furnace that has already been charged with biomass feedstock, a total of eight types of gasification reactions and their reverse reactions, as shown in the following formulas (1-1) to (1-8), for example, proceed in the gasification furnace, producing a synthesis gas containing hydrogen, carbon monoxide, carbon dioxide, and hydrocarbons. Here, the water molecules in the following formulas may be derived from the biomass feedstock or may be introduced as water vapor.

[0051] [ka]

[0052] [ka]

[0053] The mass ratio represented by [hydrogen gas] / [biomass feedstock] is preferably 0.01 to 0.05, more preferably 0.01 to 0.04, and even more preferably 0.01 to 0.03. When the mass ratio is within the above range, the reaction of carbon dioxide with hydrogen proceeds more easily, and carbon dioxide is also more easily consumed as a raw material for synthesis gas, which helps to reduce the burden on the environment. Furthermore, excess hydrogen can be recovered and reused in the synthesis gas production process, which helps to further improve energy efficiency.

[0054] After the synthesis gas production step S3 and before the Fischer-Tropsch synthesis step S6, a gas purification step S4 and a gas pressurization step S5 may be performed. In the gas purification step S4, hydrogen is mixed with the synthesis gas produced by the gasification reactions and their reverse reactions shown in the above formulas (1-1) to (1-8) to adjust the H2 / CO ratio of the synthesis gas to a predetermined target ratio. The synthesis gas is then purified by removing undesirable substances contained in the synthesis gas in order to supply it to the subsequent gas pressure increase step S5. For example, the H2 / CO ratio of the synthesis gas is preferably 2.0 or higher, more preferably 2.0 to 5.0, and even more preferably 2.0 to 3.5. By maintaining the H2 / CO ratio of the synthesis gas within the above range, unreacted hydrogen can be recovered in the FT reaction and reused in the synthesis gas production step S2. This eliminates the need to supply high-purity, high-pressure hydrogen gas to the synthesis gas production step S2, thereby improving energy efficiency. The impurity gas containing carbon dioxide, hydrocarbons, etc. removed in the gas purification step S4 may be supplied to the gas separation step S9 described later, mixed with the FT off-gas, and separated into a gasification assisting gas containing hydrogen, carbon monoxide, and carbon dioxide, and a heat source gas containing hydrocarbons. The method for purifying the synthesis gas is not particularly limited, and any known purification method can be used. In the gas pressurization step S5, the pressure of the synthesis gas to be supplied to the Fischer-Tropsch synthesis step is adjusted to a predetermined pressure (e.g., 3 MPa) according to the reaction conditions of the Fischer-Tropsch reaction, and then this synthesis gas is supplied to the subsequent Fischer-Tropsch synthesis step. The method for pressurizing the synthesis gas is not particularly limited, and any known pressure adjustment method can be used.

[0055] In the Fischer-Tropsch synthesis step S6, the synthesis gas is subjected to a Fischer-Tropsch synthesis reaction, and then FT off-gas containing hydrogen is separated to produce Fischer-Tropsch oil. The reaction conditions in the Fischer-Tropsch synthesis step S6 are not particularly limited, and known reaction conditions can be used. In the Fischer-Tropsch synthesis step S6, Fischer-Tropsch oil, which is a raw material for methanol, gasoline, etc., and FT off-gas containing hydrogen, carbon monoxide, carbon dioxide, and hydrocarbons are obtained from the synthesis gas. Examples of hydrocarbons contained in the FT off-gas include hydrocarbons having 1 to 5 carbon atoms.

[0056] In the gas separation step S9, the FT off-gas is separated into a gasification assisting gas containing hydrogen, carbon monoxide, and carbon dioxide, and a heat source gas containing hydrocarbons. The method for separating the gas is not particularly limited, and known separation methods can be used. For example, by passing the FT off-gas through a column that separates the FT off-gas by molecular size, a gasification assisting gas containing hydrogen, carbon monoxide, and carbon dioxide can be obtained, and then a heat source gas containing hydrocarbons can be obtained. Alternatively, the hydrocarbons in the off-gas can be adsorbed into the column to obtain a gasification assisting gas, and then the column can be placed under reduced pressure to recover the hydrocarbons adsorbed in the column, thereby obtaining a heat source gas containing hydrocarbons. Examples of column packing materials include alumina, activated alumina, celite, and porous polymers. Alternatively, the FT off-gas can be separated by distillation, or the FT off-gas can be cooled and the heat source gas containing hydrocarbons can be condensed and separated.

[0057] In the hydrogen supply step SH, the hydrogen in the FT off-gas is supplied to the synthesis gas production step, eliminating the need for a purification step to increase the purity of the hydrogen or a pressurization step to increase the pressure of the hydrogen before supplying it to the synthesis gas production step. Only the hydrogen in the FT off-gas may be supplied to the synthesis gas production process, or a gasification assisting gas containing hydrogen, carbon monoxide, carbon dioxide, etc. in the FT off-gas may be supplied to the synthesis gas production process. However, taking into account the energy consumption for purifying the gas, it is preferable to supply the gasification assisting gas to the synthesis gas production process. The method for supplying hydrogen in the FT off-gas to the gasification furnace is not particularly limited, and any known supply method can be used.

[0058] In a heat source gas supplying step (not shown), the heat source gas is supplied as a heat source in a synthesis gas production step. The method for burning the heat source gas is not particularly limited, and any known method can be used.

[0059] In the steam supplying step (not shown), steam is supplied to the synthesis gas production step so that the mass ratio expressed as [mass of steam] / [mass of biomass] is less than 1.0. The method for supplying water vapor is not particularly limited, and any known method can be used. There are no particular limitations on the method for adjusting the steam so that the mass ratio expressed as [mass of steam] / [mass of biomass] is less than 1.0, and adjustment may be made using a steam supply amount adjustment device such as a valve that adjusts the amount of steam supplied into the gasification furnace based on the mass of biomass supplied into the gasification furnace. The mass ratio expressed as [mass of water vapor] / [mass of biomass] is preferably 0.01 to 0.8, more preferably 0.01 to 0.5, and even more preferably 0.01 to 0.3. When the mass ratio is within the above range, it becomes easier to adjust the proportion of hydrogen contained in the synthesis gas to be higher, and carbon dioxide can be more easily consumed as a raw material, which makes it easier to further improve energy efficiency.

[0060] After the Fischer-Tropsch synthesis step S6 and before the fractionation step S8, there may be a hydrocracking step S7 in which the Fischer-Tropsch oil is hydrocracked. In the hydrocracking step S7, the heavy fraction (approximately C 21 or more) is hydrocracking using hydrogen gas to change the carbon number to C 20 This hydrocracking reaction uses catalysts and heat to break the C-C bonds in hydrocarbons with a large carbon number to produce hydrocarbons with a smaller carbon number and lower molecular weight, resulting in liquid fuels consisting of naphtha, SAF, diesel, and heavier fractions. The reaction conditions for the hydrocracking are not particularly limited, and known reaction conditions can be used. In addition, when the total mass of hydrocarbons produced after the FT synthesis reaction is 10 t or less, if the hydrocracking step S7 is performed after the Fischer-Tropsch synthesis step and before the fractionation step S8, the amount of hydrocarbons fractionated in the fractionation step S8 will be reduced, resulting in excellent energy efficiency.

[0061] In the fractionation step S8, the Fischer-Tropsch oil is hydrocracked, and then the liquid fuel and the FT off-gas are fractionated. Specifically, the liquid fuel is fractionated into naphtha fraction (boiling point less than approximately 200°C), SAF fraction (boiling point approximately 200 to 300°C), diesel fraction (boiling point approximately 200 to 350°C), and heavy fraction (boiling point above approximately 350°C). The gas obtained during fractional distillation is recovered as FT off-gas. The method of fractional distillation is not particularly limited, and any known fractional distillation method can be used.

[0062] FIG. 2 is a flowchart showing the configuration of the fuel production method according to this embodiment. The steps from the biomass raw material supply step S2 to the steam supply step can be the same as those described with reference to FIG.

[0063] In a fractionation step S8, the Fischer-Tropsch oil and the FT off-gas are fractionated after the Fischer-Tropsch synthesis step and before the Fischer-Tropsch oil is subjected to hydrorefining or hydrocracking. The method of fractional distillation is not particularly limited, and any known fractional distillation method can be used.

[0064] After the Fischer-Tropsch synthesis step, the fractionation step S8 may be followed by a hydrotreating step S17 of hydrotreating the Fischer-Tropsch oil and a hydrocracking step S7 of hydrocracking the Fischer-Tropsch oil. In the hydrorefining step S17, the unsaturated bonds of the unsaturated hydrocarbons contained in the liquid fuel after fractionation are hydrogenated to convert them into saturated hydrocarbons, which are then refined. In the hydrocracking step S7, the heavy fraction (approximately C ) obtained after fractional distillation of the Fischer-Tropsch oil is 21The above is hydrocracking using hydrogen gas. When the mass of the synthesis gas exceeds 10 tons, performing the hydrotreating step S17 and hydrocracking step S7 after the Fischer-Tropsch synthesis step and after the fractionation step S8 reduces the amount of fractionation in the fractionation step S8, resulting in excellent energy efficiency. Unlike the hydrocracking step S7, the hydrotreating step S17 does not cleave the C—C bonds of hydrocarbons, and therefore hardly produces by-products with significantly different carbon numbers and boiling points. The reaction conditions for the hydrocracking are not particularly limited, and known reaction conditions can be used. The reaction conditions for hydrotreating are not particularly limited, and known reaction conditions can be used.

[0065] The fuel production method of the present invention preferably does not include a heavy hydrocarbon removal step for removing hydrocarbons contained in the FT off-gas having a carbon number of 5 or more. By not including the heavy hydrocarbon removal step, the number of steps can be reduced, which in turn reduces energy consumption and further improves energy efficiency.

[0066] <<Fuel production system>> FIG. 3 is a schematic diagram showing the configuration of the fuel production system according to this embodiment. The fuel production system according to this embodiment is a system for carrying out the fuel production method of Fig. 1. Therefore, the explanation of the fuel production system according to this embodiment is not particularly limited as long as it can carry out the contents explained in the fuel production method of Fig. 1, and conventional devices can be used. In the gasification device 3, the biomass material, hydrogen, carbon monoxide, and carbon dioxide are reacted to produce a synthesis gas containing hydrocarbons. In a Fischer-Tropsch unit (FT unit) 6, the synthesis gas is subjected to a Fischer-Tropsch synthesis reaction, and then FT off-gas containing hydrogen is separated to produce Fischer-Tropsch oil. In the hydrogen production device or hydrogen supply device 10, the hydrogen in the FT off-gas is supplied to the gasification device. In the gas separation device 9, the FT off-gas is separated into a gasification assisting gas containing hydrogen, carbon monoxide, and carbon dioxide, and a heat source gas containing hydrocarbons. A heat source gas supply device (not shown) supplies the heat source gas as a heat source for heating a gasification furnace used to produce synthesis gas in the gasification device 3. The steam production device or steam supply device 10 supplies steam to the gasification device 3 so that the mass ratio expressed as [mass of steam] / [mass of biomass] is less than 1.0. In the hydrocracker 7, the heavy fraction (approximately C 21 The above materials are hydrocracking using hydrogen gas to obtain liquid fuel consisting of naphtha, SAF, diesel, and heavy fractions. When the total mass of hydrocarbons produced after the FT synthesis reaction is 10 tons or less, providing a hydrocracker 7 downstream of the Fischer-Tropsch unit 6 and upstream of the fractionator (S) 8 reduces the amount of hydrocarbons fractionated in the fractionator (S) 8, resulting in excellent energy efficiency. In the fractionation unit (S) 8, the Fischer-Tropsch oil is hydrocracked, and then the liquid fuel and the FT off-gas are fractionated.

[0067] FIG. 4 is a schematic diagram showing the configuration of the fuel production system according to this embodiment. The fuel production system according to this embodiment is a system for carrying out the fuel production method of Fig. 2. Therefore, the explanation of the fuel production system according to this embodiment is not particularly limited as long as it can carry out the contents explained in the fuel production method of Fig. 2, and conventional devices can be used. Furthermore, the biomass raw material supply device 2 to the Fischer-Tropsch unit 6 can be the same as those described with reference to FIG.

[0068] In a fractionator (L) 8, downstream of the Fischer-Tropsch unit and upstream of a hydrocracker that hydrocracks the Fischer-Tropsch oil, liquid fuel and the FT off-gas are fractionated.

[0069] In the hydrotreating unit 17, the unsaturated bonds of the unsaturated hydrocarbons contained in the liquid fuel after fractionation are hydrogenated to convert them into saturated hydrocarbons, which are then refined. In the hydrocracker 7, the heavy fraction (approximately C ) obtained after fractional distillation of the Fischer-Tropsch oil is 21 The above is hydrocracking using hydrogen gas. When the mass of the synthesis gas exceeds 10 tons, providing a hydrotreating unit 17 and a hydrocracking unit 7 downstream of the Fischer-Tropsch unit 6 and downstream of the fractionation unit (L) 8 reduces the amount of gas fractionated in the fractionation unit (L) 8, resulting in excellent energy efficiency.

[0070] The present invention is not limited to the above-described embodiments, and includes modifications and improvements within the scope of achieving the object of the present invention. [Explanation of symbols]

[0071] 1, 11 Fuel production system 2. Biomass raw material supply device 3 Gasifier 4 Gas purification equipment 5. Gas pressure generator 6. Fischer-Tropsch Unit (FT Unit) 7 Hydrocracker 8 Fractionation equipment 9 Gas Separator 10 Hydrogen production equipment or hydrogen supply equipment 17 Hydrotreating Unit

Claims

1. A method for producing fuel from biomass feedstock, comprising: a synthesis gas production step of reacting a biomass feedstock, hydrogen, water, and carbon dioxide to produce a synthesis gas containing hydrogen and carbon monoxide; a Fischer-Tropsch synthesis step of producing a Fischer-Tropsch oil by subjecting the synthesis gas to a Fischer-Tropsch synthesis reaction and then separating an FT off-gas containing hydrogen, The method for producing fuel, wherein the hydrogen supplied to the synthesis gas production step comprises hydrogen in the FT off-gas.

2. 2. The fuel production method according to claim 1, which does not include a heavy hydrocarbon removal step for removing hydrocarbons having a carbon number of 5 or more contained in the FT off-gas.

3. 2. The fuel production method according to claim 1, further comprising a hydrogen supply step of supplying hydrogen in the FT off-gas to the synthesis gas production step.

4. The method for producing fuel according to claim 1 , wherein only hydrogen contained in the FT off-gas is supplied as the hydrogen.

5. 2. The fuel production method according to claim 1, further comprising a gas separation step of separating the FT off-gas into a gasification-assisting gas containing hydrogen and a heat source gas containing hydrocarbons.

6. 6. The fuel production method according to claim 5, further comprising a heat source gas supplying step of supplying the heat source gas as a heat source in a synthesis gas production step.

7. 2. The fuel production method according to claim 1, further comprising a steam supplying step of supplying steam as water in the synthesis gas production step so that a mass ratio expressed as [mass of steam] / [mass of biomass] is less than 1.

0.

8. 2. The method for producing fuel according to claim 1, wherein the FT off-gas is obtained by a fractionation step (s) of fractionating a liquid fuel after the Fischer-Tropsch synthesis step and after hydrocracking the Fischer-Tropsch oil.

9. 2. The method for producing fuel according to claim 1, wherein the FT off-gas is obtained by a fractionation step (l) of fractionating the Fischer-Tropsch oil after the Fischer-Tropsch synthesis step and before hydrotreating or hydrocracking the Fischer-Tropsch oil.

10. A fuel production system for producing fuel from biomass feedstock, comprising: a gasification device that reacts a biomass feedstock, hydrogen, water, and carbon dioxide to produce a synthesis gas containing hydrogen and carbon monoxide; a Fischer-Tropsch unit for producing a Fischer-Tropsch oil by subjecting the synthesis gas to a Fischer-Tropsch synthesis reaction and then separating an FT off-gas containing hydrogen; a hydrogen supply device that supplies hydrogen in the FT off-gas to the gasification device.

11. The fuel production system according to claim 10 , wherein the fuel production system does not include a heavy hydrocarbon removal unit that removes hydrocarbons having a carbon number of 5 or more contained in the FT off-gas.

12. The fuel production system according to claim 10 , wherein the hydrogen supply device only includes a hydrogen supply device that supplies hydrogen in the FT off-gas to the gasification device.

13. The fuel production system according to claim 10 , further comprising a gas separation device that separates the FT off-gas into a gasification assisting gas containing hydrogen and a heat source gas containing hydrocarbons.

14. The fuel production system according to claim 13 , further comprising a heat source gas supply device for supplying the heat source gas as a heat source in a synthesis gas production process.

15. 11. The fuel production system according to claim 10, further comprising a steam supply device that supplies steam as water to the gasification device so that a mass ratio expressed as [mass of steam] / [mass of biomass] is less than 1.

0.

16. 11. The fuel production system according to claim 10, further comprising a fractionator (S) downstream of the Fischer-Tropsch unit and downstream of the hydrocracker that hydrocracks the Fischer-Tropsch oil, that fractionates the liquid fuel and the FT off-gas.

17. 11. The fuel production system according to claim 10, further comprising a fractionator (L) that fractionates the Fischer-Tropsch oil and the FT off-gas, downstream of the Fischer-Tropsch unit and upstream of the hydrotreating unit that hydrotreates the Fischer-Tropsch oil.

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