Method for Producing Synthesis Gas and Fuel Production System

Priority is claimed on Japanese Patent Application No. 2024-048262, filed Mar. 25, 2024, the content of which is incorporated herein by reference.

The present disclosure relates to a method for producing a synthesis gas and a fuel production system.

In the related art, efforts to mitigate climate change or reduce an impact thereof have continued, and research and development related to reducing carbon dioxide emissions has been performed to achieve this.

In recent years, as an alternative to fossil fuels, synthetic fuels obtained by using hydrogen generated using electric power generated from renewable energy and a carbon source such as carbon dioxide discharged from biomass or factories as raw materials have attracted attention.

A general procedure for producing a liquid fuel such as methanol or gasoline using biomass as a raw material is as follows. That is, the liquid fuel is produced from the biomass raw material through a gasification step of gasifying the biomass raw material, which has undergone a predetermined pretreatment, together with water or oxygen in a gasification furnace to generate a synthesis gas containing hydrogen and carbon monoxide, a cleaning step of cleaning the generated synthesis gas to remove tar, an H/CO ratio adjustment step of adjusting an H/CO ratio of the synthesis gas, which has undergone the cleaning step, to a target ratio corresponding to a liquid fuel to be produced, a desulfurization step of removing a sulfur component from the synthesis gas, which has undergone the H/CO ratio adjustment step, and a fuel production step of producing the liquid fuel from the synthesis gas, which has undergone the desulfurization step.

Here, the H/CO ratio of the synthesis gas generated through the gasification step does not reach the target ratio in many cases, resulting in a hydrogen deficiency. Therefore, in the H/CO ratio adjustment step, hydrogen is generated by reacting carbon monoxide with water, thereby increasing the H/CO ratio to the target ratio.

Japanese Unexamined Patent Application, First Publication No. 2021-147505 discloses an invention in which, in a fuel production system that produces a synthetic fuel from the biomass raw material as mentioned above, hydrogen is generated using electric power generated from renewable energy, and the generated hydrogen is mixed with the synthesis gas to be generated by a gasification furnace to adjust an H/CO ratio to a target ratio.

In the fuel production system disclosed in Japanese Unexamined Patent Application, First Publication No. 2021-147505, hydrogen is generated using electric power generated from renewable energy through an electrolytic device, and the generated hydrogen is stored in a hydrogen tank. Here, since wind power and solar light assumed as the renewable energy in Japanese Unexamined Patent Application, First Publication No. 2021-147505 are not always generated in a constant amount, a hydrogen remaining amount in the hydrogen tank may significantly fluctuate depending on environmental conditions. Therefore, in a case where the hydrogen remaining amount approaches a lower limit of the hydrogen tank, a sufficient amount of hydrogen cannot be supplied to the gasification furnace or the like, which may, in turn, lead to an increase in carbon dioxide emissions in the gasification step, the H/CO ratio adjustment step, or the like mentioned above. As a result, carbon dioxide emission intensity (which is an amount of carbon dioxide discharged to produce a unit amount of liquid fuel and also referred to as “carbon intensity”) of the liquid fuel produced by the fuel production system may deteriorate.

Additionally, in the related art, in order to operate the fuel production system, it is necessary to raise a temperature of a reaction field, a raw material, or the like to a predetermined temperature; however, in a non-steady state during temperature raising, the synthesis gas cannot be produced, which poses a problem of poor energy efficiency.

Further, in a case where hydrogen gas generated in the fuel production system exceeds a capacity of the hydrogen tank, the hydrogen gas can only be used as a fuel or discharged, which poses a problem of ineffective hydrogen utilization.

In order to solve the above-described problems, an object of the present application is to provide a method for producing a synthesis gas and a fuel production system that can effectively utilize hydrogen, improve energy efficiency, and reduce an environmental burden. Moreover, it contributes to the mitigation of climate change or the reduction of the impact.

[1] A method for producing a synthesis gas for producing a fuel from a biomass raw material, the method including:

In the method for producing a synthesis gas of the present disclosure, hydrogen can be effectively utilized as a raw material for synthesis gas production even in a non-steady state in which the fuel production system is in a preparation stage.

In addition, since a supply amount of hydrogen increases, it is possible to produce a sufficient amount of synthesis gas even in a case where no high-purity and high-pressure hydrogen or steam is supplied. Therefore, an amount of energy consumption for producing high-purity and high-pressure hydrogen or steam can be reduced, making it possible to improve energy efficiency.

Further, since the supply amount of hydrogen increases, reactions that consume carbon dioxide as a raw material also proceed more easily, making it possible to reduce carbon dioxide emissions and reduce the environmental burden.

[2] A method for producing a synthesis gas for producing a fuel from a biomass raw material, the method including:

In the method for producing a synthesis gas of the present disclosure, hydrogen can be effectively utilized as a raw material for synthesis gas production even in a non-steady state in which the fuel production system is in a preparation stage.

In addition, since the supply amount of hydrogen increases, it is possible to produce a sufficient amount of synthesis gas even in a case where a small amount of high-purity and high-pressure hydrogen or steam is supplied. Therefore, the amount of energy consumption for producing high-purity and high-pressure hydrogen or steam can be reduced, making it possible to improve energy efficiency.

Further, since the supply amount of hydrogen increases, reactions that consume carbon dioxide as a raw material also proceed more easily, making it possible to reduce carbon dioxide emissions and reduce the environmental burden.

[3] The method for producing a synthesis gas according to [1] or [2],

In the method for producing a synthesis gas of the present disclosure, hydrogen can be effectively utilized as a raw material for synthesis gas production even in a case of a low temperature in which the temperature of the gasification furnace is 700° C. or higher and lower than 850° C., in a non-steady state in which the fuel production system is in a preparation stage.

[4] The method for producing a synthesis gas according to [1] or [2],

In the method for producing a synthesis gas of the present disclosure, hydrogen can be effectively utilized as a raw material for synthesis gas production by supplying a sufficient amount of hydrogen such that the supply amount of the hydrogen gas is 100 L/day or more, even in a non-steady state in which the fuel production system is in a preparation stage.

Additionally, since the supply amount of hydrogen increases, a sufficient amount of synthesis gas can be produced even in a case where no steam or a small amount of steam is supplied. Therefore, an amount of energy consumption for producing steam can be reduced, making it possible to improve energy efficiency.

[5] A fuel production system that produces a liquid fuel from a biomass raw material, including:

In the fuel production system of the present disclosure, hydrogen can be effectively utilized as a raw material for synthesis gas production even in a non-steady state in which the fuel production system is in a preparation stage.

In addition, since the supply amount of hydrogen increases, it is possible to produce a sufficient amount of synthesis gas even in a case where no high-purity and high-pressure hydrogen or steam is supplied. Therefore, the amount of energy consumption for producing high-purity and high-pressure hydrogen or steam can be reduced, making it possible to improve energy efficiency.

Further, since the supply amount of hydrogen increases, reactions that consume carbon dioxide as a raw material also proceed more easily, making it possible to reduce carbon dioxide emissions and reduce the environmental burden.

[6] A fuel production system that produces a liquid fuel from a biomass raw material, including:

In the fuel production system of the present disclosure, hydrogen can be effectively utilized as a raw material for synthesis gas production even in a non-steady state in which the fuel production system is in a preparation stage.

Additionally, since the supply amount of hydrogen increases, it is possible to produce a sufficient amount of synthesis gas even in a case where a small amount of high-purity and high-pressure hydrogen or steam is supplied. Therefore, the amount of energy consumption for producing high-purity and high-pressure hydrogen or steam can be reduced, making it possible to improve energy efficiency.

Further, since the supply amount of hydrogen increases, reactions that consume carbon dioxide as a raw material also proceed more easily, making it possible to reduce carbon dioxide emissions and reduce the environmental burden.

[7] The fuel production system according to [5] or [6], further including:

In the fuel production system of the present disclosure, hydrogen can be effectively utilized as a raw material for synthesis gas production even in a case of a low temperature in which the temperature of the gasification furnace is 700° C. or higher and lower than 850° C., in a non-steady state in which the fuel production system is in a preparation stage.

[8] The fuel production system according to [5] or [6], further including:

In the fuel production system of the present disclosure, hydrogen can be effectively utilized as a raw material for synthesis gas production by supplying a sufficient amount of hydrogen such that the supply amount of the hydrogen gas is 100 L/day or more, even in a non-steady state in which the fuel production system is in a preparation stage.

In addition, since the supply amount of hydrogen increases, a sufficient amount of synthesis gas can be produced even in a case where no steam or a small amount of steam is supplied. Therefore, the amount of energy consumption for producing steam can be reduced, making it possible to improve energy efficiency.

[9] The fuel production system according to [5] or [6], further including:

In the fuel production system of the present disclosure, the synthesis gas can be produced even in a non-steady state in which the fuel production system is in a preparation stage, and the synthesis gas can be used as a raw material of the liquid fuel, allowing for effective utilization.

Additionally, even in a case where the gasification rate is not sufficient, the obtained synthesis gas can be used as a heat source of the gasification furnace, making it possible to reduce the amount of energy consumption and improve energy efficiency.

Further, by effectively utilizing the obtained synthesis gas, the emissions to the environment can be reduced, making it possible to reduce the environmental burden.

According to the present disclosure, it is possible to provide a method for producing a synthesis gas and a fuel production system that can effectively utilize hydrogen, improve energy efficiency, and reduce an environmental burden.

Hereinafter, embodiments of a fuel production method in the present disclosure will be specifically described. Note that the present disclosure is not limited to the following embodiments.

The fuel production method according to one embodiment of the present disclosure includes supplying a hydrogen gas such that a mass ratio represented by [mass of hydrogen gas]/[mass of biomass] is 0.01 to 0.05 in gasification of a biomass raw material.

is a flowchart showing a configuration of the fuel production method according to the present embodiment.

As shown in, the fuel production method according to the embodiment includes a biomass raw material supply step Sof supplying a biomass raw material to a gasification furnace for producing a synthesis gas, a hydrogen supply step Sof supplying hydrogen to the gasification furnace, a synthesis gas production step Sof reacting the biomass raw material, hydrogen, steam, and the like to produce a synthesis gas containing hydrocarbons, a Fischer-Tropsch synthesis step Sof subjecting the generated synthesis gas to a Fischer-Tropsch (hereinafter, sometimes referred to as “FT”) synthesis reaction to produce a Fischer-Tropsch oil, a hydrocracking step Sof subjecting a heavy fraction (generally, Cor more) contained in the Fischer-Tropsch oil to hydrocracking using a hydrogen gas to reduce the carbon number to Cor less, and a distillation step Sof distilling the Fischer-Tropsch oil after hydrocracking to separate a liquid fuel and the FT off-gas.

In the fuel production method according to the embodiment, in the hydrogen supply step Sof supplying hydrogen to the gasification furnace, the hydrogen gas is supplied such that a mass ratio represented by [mass of hydrogen gas]/[mass of biomass] is 0.01 to 0.05.

In the biomass raw material supply step S, a predetermined pretreatment is performed on the biomass raw material such as rice husks, bagasse, and wood, and the biomass raw material subjected to the pretreatment is supplied to the gasification furnace of a gasification device that performs the synthesis gas production step Svia a raw material supply path. Here, the pretreatment for the biomass raw material includes, for example, a drying step of drying the raw material, a grinding step of grinding the raw material, and the like.

In the hydrogen supply step S, hydrogen is supplied to the gasification furnace of the gasification device. Hydrogen may be supplied by, for example, generating hydrogen through electrolysis of water.

The supply amount of hydrogen is such that the mass ratio represented by [mass of hydrogen gas]/[mass of biomass] is 0.01 to 0.05, preferably 0.01 to 0.04, and more preferably 0.01 to 0.03. When the mass ratio is within the above-described range, the proportion of hydrogen contained in the synthesis gas to be supplied to the Fischer-Tropsch synthesis step Sis more easily adjusted to be larger, making it easier to consume carbon dioxide as a raw material. Therefore, the synthesis gas can be produced even in a case where no steam is supplied, and hydrogen can be effectively used, facilitating further improvement in energy efficiency.