WO2021261417A1

WO2021261417A1 - Hydrocarbon generation system

Info

Publication number: WO2021261417A1
Application number: PCT/JP2021/023306
Authority: WO
Inventors: 健太郎成相; 巧遠藤; 博之鎌田; 光亮稲葉; 順辻川; 範貴水上
Original assignee: 株式会社Ihi
Priority date: 2020-06-22
Filing date: 2021-06-21
Publication date: 2021-12-30
Also published as: JP7392854B2; JPWO2021261417A1

Abstract

A hydrocarbon generation system (1) is provided with a bioreactor (10) that generates a bio-gas including methane and carbon dioxide. The hydrocarbon generation system (1) is provided with a hydrocarbon generation unit (30) that generates hydrocarbon from raw materials including the bio-gas and hydrogen. The hydrocarbon generation system (1) is provided with a measurement unit (50) that measures the concentration of carbon dioxide in the bio-gas and the flow rate of the bio-gas supplied to the hydrocarbon generation unit (30). In the hydrocarbon generation system (1), hydrogen is supplied to the hydrocarbon generation unit (30) in a quantity according to the concentration of carbon dioxide and the flow rate of the bio-gas measured by the measurement unit (50).

Description

Hydrocarbon generation system

This disclosure relates to a hydrocarbon generation system.

In recent years, in order to suppress the increase in carbon dioxide concentration in the atmosphere, the use of renewable energy such as biomass instead of fossil resources such as natural gas has been promoted. As a method of using biomass, it is known to use methane obtained by methane fermentation of biomass as an energy source.

However, the biogas obtained by methane fermentation contains not only methane but also carbon dioxide, which is usually about 10 to several tens of percent. Therefore, it is not easy to directly use biogas as a raw material for city gas or the like, which requires a high concentration of methane.

Therefore, a method for producing high-purity methane by increasing the methane concentration of biogas has been developed. As such a method, Patent Document 1 discloses a method for producing high-purity methane, which comprises a concentration step of increasing the methane concentration of biogas by contacting the biogas with a physical absorption liquid and a chemical absorption liquid. There is.

Japanese Unexamined Patent Publication No. 2014-88524

According to the method of Patent Document 1, since the methane concentration of biogas can be increased, it is expected to be used as city gas by injecting high-purity methane into an existing gas conduit. However, the above method requires an absorption tank for bringing the biogas into contact with the absorption liquid, a regeneration tank for regenerating the absorption liquid, and the like. From the viewpoint of carbon cycle and global warming countermeasures, it is desirable that carbon dioxide produced by biogas is recycled as a valuable resource without being released into the atmosphere.

Therefore, it is an object of the present disclosure to provide a hydrocarbon generation system that can be used as a valuable resource without separating carbon dioxide contained in biogas.

The hydrocarbon generation system according to the present disclosure includes a bioreactor that produces biogas containing methane and carbon dioxide. The hydrocarbon generation system comprises a hydrocarbon generator that produces a hydrocarbon from a raw material containing biogas and hydrogen. The hydrocarbon generation system includes a measurement unit that measures the concentration of carbon dioxide in the biogas supplied to the hydrocarbon generation unit and the flow rate of the biogas. In the hydrocarbon generation system, an amount of hydrogen corresponding to the concentration of carbon dioxide measured by the measurement unit and the flow rate of biogas is supplied to the hydrocarbon generation unit.

Hydrocarbons may contain at least one of paraffin and olefin. The hydrocarbon generator may include a metanation apparatus that produces methane by metanation from raw materials containing biogas and hydrogen. The hydrocarbon generator may include an FT synthesizer that produces at least one of paraffin and olefin hydrocarbons by a Fischer-Tropsch reaction from a raw material containing biogas and hydrogen. The hydrocarbon generator consists of an FT synthesizer that produces at least one of paraffin and olefin hydrocarbons from a raw material containing biogas and hydrogen by a Fischer-Tropsch reaction, and unreacted carbon dioxide discharged from the FT synthesizer. And a metanation device that produces methane by metanation from a raw material containing hydrogen. The hydrocarbon generator consists of an FT synthesizer that produces at least one of paraffin and olefin hydrocarbons from a raw material containing biogas and hydrogen by a Fischer-Tropsch reaction, and methane by metanation from a raw material containing biogas and hydrogen. May include a metanation device that produces. The hydrocarbon generation system further comprises a hydrocarbon pre-generation unit that produces a hydrocarbon from a gas containing a gas having a higher carbon dioxide concentration than biogas and a raw material containing hydrogen, and the hydrocarbon generation unit is discharged from the hydrocarbon pre-generation unit. Hydrocarbons may be produced from raw materials containing unreacted carbon dioxide, biogas and hydrogen. The hydrocarbon pre-producing unit may include a methanation device that produces methane by metanation, and the hydrocarbon generating unit may include a meta-nation device that produces methane by metanation. The bioreactor includes a fermenter, and the fermenter may be heated by the heat of reaction generated in the hydrocarbon generator.

According to the present disclosure, it is possible to provide a hydrocarbon generation system that can be used as a valuable resource without separating carbon dioxide contained in biogas.

FIG. 1 is a schematic view showing a hydrocarbon generation system according to an embodiment. FIG. 2 is a schematic view showing an example of a hydrocarbon generation unit according to an embodiment. FIG. 3 is a schematic view showing an example of a hydrocarbon generation unit according to an embodiment. FIG. 4 is a schematic diagram showing a hydrocarbon generation system according to an embodiment.

Hereinafter, some exemplary embodiments will be described with reference to the drawings. The dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

[First Embodiment]
First, the hydrocarbon generation system 1 according to the first embodiment will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the hydrocarbon generation system 1 according to the present embodiment includes a bioreactor 10, a purification unit 20, a hydrocarbon generation unit 30, a hydrogen supply unit 40, a measurement unit 50, and a control unit 60. And. In the hydrocarbon generation system 1 according to the present embodiment, the hydrocarbon generation unit 30 can generate hydrocarbons from the biogas without recovering the biogas generated in the bioreactor 10 by a carbon dioxide recovery device or the like. .. Therefore, carbon dioxide contained in biogas can be used as a valuable resource without being separated.

(Bioreactor 10)
The bioreactor 10 produces biogas containing methane and carbon dioxide. Biogas can be produced from biomass as a raw material. Biomass is a resource derived from animals and plants, and by using such renewable energy instead of fossil resources, it is possible to suppress the emission of carbon dioxide, which is considered to be one of the causes of global warming. Biomass includes, for example, wood, herbs, paper, livestock excrement, domestic wastewater such as sewage sludge and septic tank sludge, and organic matter such as food waste. In order to efficiently generate biogas, biomass that has undergone pretreatment such as crushing and diluting the supplied raw material and removing foreign substances in the supplied raw material is supplied to the bioreactor 10. May be good.

The bioreactor 10 may be a batch type in which the supply, fermentation and discharge of raw materials are repeated as one unit, or may be a continuous type in which the supply, fermentation and discharge of raw materials are continuously performed simultaneously. The bioreactor 10 may include a fermenter for performing a methane fermentation treatment. The bioreactor 10 may include only a single fermenter or may include a plurality of fermenters. The bioreactor 10 may include a heating unit that heats the temperature in the fermenter to a predetermined temperature so that the fermentation temperature becomes the optimum temperature.

The bioreactor 10 includes a fermenter, and the fermenter may be heated by the reaction heat generated in the hydrocarbon generation unit 30. As will be described later, the hydrocarbon generation unit 30 can generate a hydrocarbon by a methanation reaction, a Fischer-Tropsch reaction, or the like, and these reactions are generally exothermic reactions. By heating the fermenter with this heat of reaction, the heat energy generated by the reaction can be effectively utilized.

The fermenter may contain microorganisms for methane fermentation. The method for retaining microorganisms is not particularly limited, and examples thereof include a fixed bed method, a fluidized bed method, and a USAB (upward flow anaerobic sludge bed) method. In the fixed bed method, a carrier carrying a microorganism is usually filled in a fermenter. In the fluidized bed method, a carrier carrying a microorganism is usually housed in a fermenter and flows in the fermenter. In the USAB method, a granule in which microorganisms are aggregated without being supported on a carrier is usually housed in a fermenter. The particle size of the granule is, for example, about 0.5 to 2 mm.

In methane fermentation, many anaerobic microorganisms produce methane from biomass. Specifically, organic substances including proteins, carbohydrates and lipids are hydrolyzed to produce amino acids, sugars and fatty acids. Amino acids, sugars and fatty acids are decomposed into acetic acid, carbon dioxide and hydrogen. Then, the methanogen produces methane from acetic acid, carbon dioxide and hydrogen. In the bioreactor 10, digestive juice is also produced by methane fermentation.

The methanogen may contain a high temperature methanogen that is active at a high temperature such as 50 ° C to 60 ° C, and may contain a medium temperature methanogen that is active at a medium temperature such as 35 ° C to 38 ° C. You may be. When high temperature methanogens are used, the time for methane fermentation can be shortened. When low-temperature methane bacteria are used, the temperature required for heating the fermenter can be reduced.

(Refining unit 20)
Biogas includes methane and carbon dioxide as described above. The carbon dioxide contained in the biogas is, for example, 10% by volume to 40% by volume. However, in addition to methane and carbon dioxide, biomass may contain sulfur components such as hydrogen sulfide and methyl mercaptan, organic polysiloxane, and impurities such as ammonia, depending on the components contained in the raw material biomass. .. Therefore, by removing the impurities as described above by the purification unit 20, it is possible to suppress the adhesion of impurities to the hydrocarbon generation unit 30 and the piping, which will be described later, and the poisoning of the catalyst of the hydrocarbon generation unit 30. .. When the need to remove these impurities is low, the purification unit 20 is not required, so that the hydrocarbon generation system 1 does not have to include the purification unit 20.

(Hydrocarbon generator 30)
The hydrocarbon generation unit 30 generates a hydrocarbon from a raw material containing biogas and hydrogen. By generating hydrocarbons from the biogas generated by the bioreactor 10 and the hydrogen-containing raw materials supplied by the hydrogen supply unit 40, carbon dioxide contained in the biogas can be used as a valuable resource, and is a fossil resource. The use of can be reduced. Since the amount of carbon dioxide in the product can be reduced, there is less need to recover it with a carbon dioxide recovery device that uses a chemical absorption method, etc., and the equipment required to recover carbon dioxide from biogas Installation and maintenance costs can be reduced.

The hydrocarbon generation unit 30 includes a reactor, and the catalyst may be arranged in a flow path through which the raw material supplied to the reactor passes. Hydrocarbons can be produced by contacting the raw material with the catalyst. The hydrocarbon preferably contains, for example, at least one of paraffin and olefin. Paraffin means alkane and olefin means alkene. Since these hydrocarbons can be used as an energy source and a raw material for chemical products, they have high utility value.

Hydrocarbons can be produced by a methanation reaction, a Fischer-Tropsch reaction, or the like, as described later. These reactions are generally exothermic reactions, and the temperature of the catalyst layer may reach 700 ° C. or higher depending on the conditions. However, since biogas contains methane and the concentration of carbon dioxide is reduced by hydrocarbons, the reaction can proceed under relatively mild conditions. Therefore, the generation of heat of reaction can be suppressed, and the heat resistant temperature of the catalyst layer and the reactor can be lowered. These reaction conditions are, for example, a reaction temperature of 200 ° C. to 400 ° C. and a pressure in the reactor of 0.1 MPa to 10 MPa.

The hydrocarbon generation unit 30 may include a metanation device 31 that produces methane by metanation from a raw material containing biogas and hydrogen. In the methanation reaction, a product containing methane and water can be produced from a raw material containing carbon dioxide and hydrogen. Therefore, by removing water from the product, a product having a high methane concentration can be obtained. Therefore, the methane obtained by the hydrocarbon generation unit 30 can be directly used as an energy source in the factory or directly supplied as city gas. The methanation device 31 may include a known reactor such as a multi-tube reactor such as a shell-and-tube reactor.

The selectivity of methane produced by methane is high, for example, methane is produced from 85% or more of the carbon dioxide contained in the raw material. The rate at which methane is produced depends on the reaction conditions and may be 90% or more, or 95% or more.

The catalyst used in the metanation apparatus 31 is not particularly limited as long as it can generate methane, and a known catalyst such as a nickel catalyst or a ruthenium catalyst can be used. A nickel catalyst is a catalyst containing nickel as an active ingredient, and a ruthenium catalyst is a catalyst containing ruthenium as an active ingredient. The content of the active ingredient is preferably 0.5% by mass or more, and more preferably 10% by mass or more of the whole catalyst. When nickel is contained as an active ingredient, the content of the active ingredient is preferably 10% by mass or more of the entire catalyst, and when ruthenium is contained as the active ingredient, the content of the active ingredient is the content of the entire catalyst. It is preferably 0.5% by mass or more. From the viewpoint of cost and high methane selectivity, it is preferable that the metanation apparatus 31 is provided with a nickel catalyst.

The hydrocarbon generation unit 30 may include an FT synthesizer 32 that produces a hydrocarbon of at least one of paraffin and olefin by a Fischer-Tropsch reaction from a raw material containing biogas and hydrogen. In the Fischer-Tropsch reaction, hydrocarbons of at least one of paraffin and olefin can be produced from a raw material containing carbon dioxide and hydrogen.

It is preferable that at least one of paraffin and olefin contains a hydrocarbon having 1 to 4 carbon atoms. Examples of paraffin having 1 to 4 carbon atoms include methane, ethane, propane and butane. Examples of olefins having 1 to 4 carbon atoms include ethylene, propylene, 1-butene, 2-butene, isobutene and 1,3-butadiene. Among these, olefins having 2 or more and 4 or less carbon atoms are useful because they can be used as raw materials for plastics. Further, the product produced by the FT synthesizer 32 may contain a compound other than the above. The FT synthesizer 32 may include, for example, a known reactor such as a multi-tube reactor such as a shell-and-tube reactor, a fluidized bed reactor or a slurry bed reactor.

The product produced by the Fischer-Tropsch reaction usually contains multiple types of hydrocarbons. In the product produced by the Fischer-Tropsch reaction, for example, hydrocarbons of at least one of paraffin and olefin are produced from carbon dioxide of 20% or more and less than 85% of the carbon dioxide contained in the raw material. The rate at which hydrocarbons are produced depends on the reaction conditions and may be 35% or more, or 50% or more. Further, the ratio of hydrocarbons produced may be 65% or less, or 55% or less.

The catalyst used in the FT synthesizer 32 is not particularly limited as long as it can generate a hydrocarbon of at least one of paraffin and olefin, and a known catalyst such as an iron catalyst or a cobalt catalyst can be used. .. Iron catalysts can mainly produce light hydrocarbons, and cobalt catalysts can mainly produce heavy hydrocarbons, including waxes. Further, the iron catalyst can mainly produce olefins and paraffin, and the cobalt catalyst can mainly produce paraffin. The iron catalyst is a catalyst containing iron as an active ingredient, and the cobalt catalyst is a catalyst containing cobalt as an active ingredient. The content of the active ingredient is preferably 10% by mass or more of the whole catalyst. It is preferable that the FT synthesizer 32 is provided with an iron catalyst. This makes it possible to produce a light olefin (lower olefin) that can also be used as a raw material for plastics.

The hydrocarbon generation unit 30 may include at least one of the methanation device 31 and the FT synthesizer 32. That is, the hydrocarbon generation unit 30 may include only the methanation device 31, may include only the FT synthesizer 32, or may include both the metanation device 31 and the FT synthesizer 32. ..

The hydrocarbon generation unit 30 may include an FT synthesizer 32 and a methanation device 31, as shown in FIG. 2, for example. The FT synthesizer 32 may produce at least one of paraffin and olefin hydrocarbons from a raw material containing biogas and hydrogen by a Fischer-Tropsch reaction. The methanation device 31 may generate methane by methanation from a raw material containing unreacted carbon dioxide and hydrogen discharged from the FT synthesizer 32.

The FT synthesizer 32 can generate at least one of paraffin and olefin hydrocarbons from carbon dioxide, but is discharged from the FT synthesizer 32 without being converted to hydrocarbons as compared with the metanation device 31. There is a tendency for a large amount of unreacted carbon dioxide. Therefore, by arranging the methanation device 31 in series after the FT synthesizer 32, methane can be produced from unreacted carbon dioxide with a high selectivity by the methanation device 31. Therefore, the amount of carbon dioxide discharged as an unreacted product from the hydrocarbon generation unit 30 can be reduced, and the unreacted carbon dioxide can be effectively used. In addition, since the concentration of carbon dioxide in the product can be reduced, the amount of heat in the product can be improved. Since the FT synthesizer 32 produces not only hydrocarbons but also water, it is preferable that a gas-liquid separator capable of removing water is provided between the FT synthesizer 32 and the methanation device 31. ..

Further, as shown in FIG. 3, the hydrocarbon generation unit 30 may include an FT synthesizer 32 and a methanation device 31. The FT synthesizer 32 may produce at least one of paraffin and olefin hydrocarbons from a raw material containing biogas and hydrogen by a Fischer-Tropsch reaction. The methanation device 31 may generate methane by methanation from a raw material containing biogas and hydrogen.

By arranging the metanation device 31 and the FT synthesizer 32 in parallel in this way, the metanation device 31 can generate methane with a high selectivity. In addition, the FT synthesizer 32 can generate at least one of paraffin and olefin hydrocarbons. Further, the calorific value of the gas generated by the metanation apparatus 31 can be adjusted by mixing the methane produced by the metanation apparatus 31 and the hydrocarbon produced by the FT synthesis apparatus 32.

Note that FIGS. 2 and 3 have described a mode in which the metanation device 31 and the FT synthesizer 32 are arranged in series or in parallel. However, the hydrocarbon generation unit 30 may be a combination of these. For example, even if the metanation device 31 and the FT synthesizer 32 are arranged in parallel as in the form of FIG. 3, and the metanation device 31 is arranged in series as in the form of FIG. 2 after the FT synthesizer 32. good.

Further, in FIGS. 2 and 3, an example in which two different hydrogen supply units 40 supply hydrogen to the FT synthesizer 32 and the metanation device 31 has been described, but the FT synthesizer 32 and the meta are described by a common hydrogen supply unit 40. Hydrogen may be supplied to the nation device 31.

The methanation device 31 may include only a single reactor, or may include a plurality of reactors. Similarly, the FT synthesizer 32 may include only a single reactor or may include a plurality of reactors. The number of reactors can be appropriately determined, but when the concentration of carbon dioxide in the biogas is high, it is preferable that the hydrocarbon generation unit 30 includes a plurality of reactors. On the other hand, when the concentration of carbon dioxide in the biogas is low, the hydrocarbon generator 30 may contain only a single reactor. When the methanation device 31 and the FT synthesizer 32 include a plurality of reactors, each reactor may be arranged in series or in parallel.

When the product produced by the hydrocarbon generation unit 30 contains a plurality of types of hydrocarbons, the hydrocarbon generation system 1 may include a separation device that separates hydrocarbons according to the chemical structure by fractional distillation or the like. The separation device may include at least one separation column such as a demethane column, a deethane column, a deethylene column, a depropane column, a depropylene column, a debutane column and a debutene column. With these separation towers, a plurality of types of hydrocarbons can be separated according to the chemical structure such as methane, ethane, ethylene, propane, propylene, butane and butene.

(Hydrogen supply unit 40)
The hydrogen supply unit 40 supplies hydrogen to the hydrocarbon generation unit 30. As shown in FIG. 1, the hydrogen supply unit 40 may include a hydrogen generation unit 41 and a hydrogen tank 42. The hydrogen generation unit 41 is not particularly limited as long as it can generate hydrogen, but it is preferable to use renewable energy to generate hydrogen. By utilizing renewable energy, carbon dioxide emissions can be reduced as a whole in the hydrocarbon generation system 1. The hydrogen generation unit 41 may use renewable energy such as solar power, wind power, and hydraulic power to electrolyze water to generate hydrogen. Further, the hydrogen supply unit 40 may gasify the biomass to generate hydrogen. The hydrogen tank 42 may store the hydrogen generated by the hydrogen generation unit 41, or a commercially available hydrogen tank filled with hydrogen may be used.

Hydrogen may be directly supplied from the hydrogen generation unit 41 to the hydrocarbon generation unit 30 without going through the hydrogen tank 42, or may be supplied from the hydrogen tank 42 to the hydrocarbon generation unit 30. The mixed gas containing carbon dioxide and hydrogen may be compressed by a compressor and supplied to the hydrocarbon generation unit 30.

(Measurement unit 50)
The measuring unit 50 measures the concentration of carbon dioxide in the biogas supplied to the hydrocarbon generating unit 30 and the flow rate of the biogas. In the hydrocarbon generation system 1, an amount of hydrogen corresponding to the concentration of carbon dioxide measured by the measurement unit 50 and the flow rate of biogas is supplied to the hydrocarbon generation unit 30. The concentration of carbon dioxide contained in biogas and the flow rate of biogas may vary depending on a plurality of factors such as the state of bioreactor 10, microorganisms and biomass contained in raw materials. Therefore, when a predetermined fixed amount of hydrogen is supplied to the hydrocarbon generation unit 30, the amount of carbon dioxide supplied to the hydrocarbon generation unit 30 varies depending on the above-mentioned plurality of elements, and the target hydrocarbon is efficiently produced. It may not be possible to obtain it well. Further, in order to efficiently obtain a hydrocarbon having a desired chemical structure, it is preferable to make an optimum ratio of carbon dioxide and hydrogen supplied to the hydrocarbon generation unit 30.

Therefore, the concentration of carbon dioxide in the biogas and the flow rate of the biogas are measured, and hydrogen is supplied to the hydrocarbon generation unit 30 according to the concentration of carbon dioxide and the flow rate of the biogas. As a result, the mixed gas adjusted so that the ratio of carbon dioxide and hydrogen is within a predetermined range can be supplied to the hydrocarbon generation unit 30. This makes it possible to efficiently generate hydrocarbons of a desired chemical species from carbon dioxide in biogas.

The ratio of the amount of hydrogen to the carbon dioxide supplied to the hydrocarbon generation unit 30 can be appropriately set depending on the target chemical species, but for example, the molar ratio may be 1 or more, or 2 or more. May be good. Further, the ratio of the amount of hydrogen to the carbon dioxide supplied to the hydrocarbon generation unit 30 may be, for example, less than 8 or less than 5 in terms of molar ratio. In the case of metanation, the _{ratio of H 2} / CO ₂ is preferably around 4.0. Further, in the case of olefin synthesis, the _{vicinity of H 2} / CO ₂ = 3.0 is preferable.

The measuring unit 50 may include a densitometer and a flow meter. The densitometer is not particularly limited as long as it can measure the concentration of carbon dioxide, and a known densitometer can be used. The flow meter is not particularly limited as long as it can measure the flow rate of biogas, and a known flow meter can be used. The measuring unit 50 may include an integrated measuring instrument capable of measuring the concentration and the flow rate, or may include a plurality of separate measuring instruments in which the densitometer and the flow meter are separated from each other. The hydrogen supply unit 40 may adjust the hydrogen supply amount based on the signal related to the concentration of carbon dioxide generated by the measurement unit 50 and the flow rate of biogas.

(Control unit 60)
The hydrocarbon generation system 1 may include a control unit 60 that controls the amount of hydrogen supplied from the hydrogen supply unit 40. The control unit 60 may calculate, for example, the amount of hydrogen supplied by the hydrogen supply unit 40 based on the signal generated by the measurement unit 50. The control unit 60 may control the hydrogen supply unit 40 so that the calculated amount of hydrogen is supplied to the hydrocarbon generation unit 30. The control unit 60 may adjust the amount of hydrogen supplied to the hydrocarbon generation unit 30 by a flow rate regulator such as a pump. The control unit 60 may control the hydrogen supply amount of at least one of the hydrogen generation unit 41 and the hydrogen tank 42. When the hydrogen supply unit 40 includes the hydrogen generation unit 41 and the hydrogen tank 42, the control unit 60 may control the amount of hydrogen generated by the hydrogen generation unit 41 according to the remaining amount of the hydrogen tank 42.

The control unit 60 may include a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU can read the program stored in the ROM and execute instructions such as arithmetic and control according to the program. The program may include, for example, a process of calculating the supply of hydrogen from the concentration of carbon dioxide and the flow rate of biogas. The program may be stored in advance in a recording medium other than the ROM, or may be supplied to the recording medium via a wide area communication network including the Internet or the like. The RAM stores information acquired from the measurement unit 50 or the like, and the CPU can read the information stored in the RAM and use it for processing such as calculation.

As described above, the hydrocarbon generation system 1 according to the present embodiment has a bioreactor 10 that produces biogas containing methane and carbon dioxide, and a hydrocarbon generation that produces hydrocarbons from a raw material containing biogas and hydrogen. A unit 30 is provided. Since hydrocarbons are generated from carbon dioxide in the hydrocarbon generation unit 30, carbon dioxide contained in biogas can be used as a valuable resource without being separated by a carbon dioxide recovery device using a chemical absorption method or the like. can. Therefore, the installation and maintenance costs required for the carbon dioxide capture device can be reduced. In addition, since biogas is used as a raw material, the use of fossil resources such as natural gas can be reduced.

Further, the hydrocarbon generation system 1 according to the present embodiment further includes a measurement unit 50 for measuring the concentration of carbon dioxide in the biogas supplied to the hydrocarbon generation unit 30 and the flow rate of the biogas. Then, an amount of hydrogen corresponding to the concentration of carbon dioxide measured by the measuring unit 50 and the flow rate of the biogas is supplied to the hydrocarbon generating unit 30. Therefore, a mixed gas adjusted so that the ratio of carbon dioxide and hydrogen is within a predetermined range can be supplied to the hydrocarbon generation unit 30, and the target hydrocarbon can be efficiently produced from the carbon dioxide in the biogas. Can be generated well.

[Second Embodiment]
Next, the hydrocarbon generation system 1 according to the second embodiment will be described with reference to FIG.

As shown in FIG. 4, the hydrocarbon generation system 1 has a bioreactor 10, a purification unit 20, a hydrocarbon generation unit 30, a hydrogen supply unit 40, and a measurement unit, similarly to the hydrocarbon generation system 1 according to the first embodiment. It includes 50 and a control unit 60. Further, the hydrocarbon generation system 1 according to the present embodiment includes a carbon dioxide recovery device 70, a hydrocarbon pre-generation unit 35, a hydrogen supply unit 45, a measurement unit 51, and a control unit 61.

The bioreactor 10, the purification unit 20, the hydrocarbon generation unit 30, the hydrogen supply unit 40, the measurement unit 50, and the control unit 60 are the same as those of the hydrocarbon generation system 1 according to the first embodiment, and thus the description thereof will be omitted. .. Further, since the hydrocarbon pre-generation unit 35, the hydrogen supply unit 45, the measurement unit 51, and the control unit 61 are the same as the above-mentioned hydrocarbon generation unit 30, hydrogen supply unit 40, measurement unit 50, and control unit 60. , The description is omitted. Further, since the hydrogen supply unit 45 includes a hydrogen generation unit 46 and a hydrogen tank 47, and the hydrogen generation unit 46 and the hydrogen tank 47 are the same as the hydrogen generation unit 41 and the hydrogen tank 42, the description thereof will be omitted.

The carbon dioxide recovery device 70 recovers carbon dioxide from a gas containing carbon dioxide emitted from a carbon dioxide generation source. The carbon dioxide generation source is, for example, a power plant or a factory that emits carbon dioxide by burning fuel. The carbon dioxide recovery device 70 discharges a gas having a carbon dioxide concentration higher than that of the gas to be recovered from the gas containing carbon dioxide to be recovered. The carbon dioxide recovery device 70 can recover carbon dioxide by, for example, a chemical absorption method, a pressure swing adsorption method, a temperature swing adsorption method, a membrane separation concentration method, or the like.

The concentration of carbon dioxide emitted from the carbon dioxide recovery device 70 may be higher than the concentration of carbon dioxide in the biogas. The gas emitted by the carbon dioxide capture device 70 contains, for example, 90% or more carbon dioxide in terms of molar ratio. The concentration of carbon dioxide emitted from the carbon dioxide recovery device 70 is preferably 95% or more, more preferably 99% or more in terms of molar ratio.

The high-concentration carbon dioxide emitted from the carbon dioxide recovery device 70 is supplied to the hydrocarbon pre-generation unit 35. The concentration of carbon dioxide in the gas supplied to the hydrocarbon pre-generating unit 35 and the flow rate of biogas are measured by the measuring unit 51. Similar to the hydrogen supply unit 40, the hydrogen supply unit 45 may adjust the hydrogen supply amount based on the signals related to the concentration of carbon dioxide generated by the measurement unit 51 and the flow rate of the biogas. Similar to the control unit 60, the control unit 61 may calculate the amount of hydrogen supplied by the hydrogen supply unit 45 based on the signal generated by the measurement unit 51. Similar to the control unit 60, the control unit 61 may control the hydrogen supply unit 45 so that the calculated amount of hydrogen is supplied to the hydrocarbon pre-generation unit 35. Similar to the control unit 60, the control unit 61 may control the hydrogen supply amount of at least one of the hydrogen generation unit 46 and the hydrogen tank 47. Then, the amount of hydrogen corresponding to the concentration of carbon dioxide measured by the measuring unit 51 and the flow rate of the biogas is supplied to the hydrocarbon pre-generating unit 35.

The hydrocarbon pre-generating unit 35 may generate a hydrocarbon from a gas having a carbon dioxide concentration higher than that of biogas and a raw material containing hydrogen. The hydrocarbon produced by the hydrocarbon pre-producing unit 35 may contain at least one of paraffin and olefin. Like the hydrocarbon generation unit 30, the hydrocarbon pre-generation unit 35 may include at least one of a methanation device and an FT synthesis device. Further, the metanation apparatus may include only a single reactor, or may include a plurality of reactors. Similarly, the FT synthesizer may include only a single reactor or may include multiple reactors. When the methanation device and the FT synthesizer include a plurality of reactors, each reactor may be arranged in series or in parallel.

A cooler 81 and a gas-liquid separator 82 may be provided in the pipe connecting the hydrocarbon pre-generating unit 35 and the hydrocarbon generating unit 30. The product produced by the hydrocarbon pre-producing unit 35 is cooled by the cooler 81, the water contained in the product is condensed, and the water is removed from the product by the gas-liquid separator 82. The product from which the water has been removed is supplied to the hydrocarbon generation unit 30.

The hydrocarbon generation unit 30 may generate a hydrocarbon from a raw material containing unreacted carbon dioxide, biogas and hydrogen discharged from the hydrocarbon pre-generation unit 35. The hydrocarbon produced by the hydrocarbon generator 30 may contain at least one of paraffin and olefin. The hydrocarbon generation unit 30 may include at least one of the methanation device 31 and the FT synthesizer 32, as in the above embodiment. Further, the metanation device 31 may include only a single reactor, or may include a plurality of reactors. Similarly, the FT synthesizer 32 may include only a single reactor or may include a plurality of reactors. When the methanation device 31 and the FT synthesizer 32 include a plurality of reactors, each reactor may be arranged in series or in parallel.

A connection pipe may be provided at the discharge port for discharging the product generated by the hydrocarbon generation unit 30, and a cooler 83 and a gas-liquid separator 84 may be provided at the connection pipe. The product produced by the hydrocarbon generator 30 is cooled by the cooler 83 to condense the water, and the water is removed by the gas-liquid separator 84.

Since the product produced by the hydrocarbon generation unit 30 contains high-concentration hydrocarbons, it can be used as it is as an energy source in a factory or directly supplied as city gas. Hydrocarbons such as olefins can also be used as raw materials for plastics. In the hydrocarbon generation unit 30, various hydrocarbons may be separated by the separation device as described above.

As described above, the hydrocarbon generation system 1 according to the present embodiment has a bioreactor 10 that produces biogas containing methane and carbon dioxide, and a hydrocarbon generation that produces hydrocarbons from a raw material containing biogas and hydrogen. A unit 30 is provided. Since hydrocarbons are generated from carbon dioxide in the hydrocarbon generation unit 30, carbon dioxide contained in biogas can be used as a valuable resource without being separated by a carbon dioxide recovery device using a chemical absorption method or the like. can. In addition, since biogas is used as a raw material, the use of fossil resources such as natural gas can be reduced.

Further, the hydrocarbon generation system 1 may further include a hydrocarbon pre-generation unit 35 that generates a hydrocarbon from a gas having a carbon dioxide concentration higher than that of biogas and a raw material containing hydrogen. The hydrocarbon generation unit 30 may generate a hydrocarbon from a raw material containing unreacted carbon dioxide, biogas and hydrogen discharged from the hydrocarbon pre-generation unit 35.

As a result, carbon dioxide is consumed in the hydrocarbon pre-generation unit 35, and a gas having a carbon dioxide concentration lower than that supplied to the hydrocarbon pre-generation unit 35 is supplied to the hydrocarbon generation unit 30. Since the partial pressure of carbon dioxide in the hydrocarbon pre-generating unit 35 is high, hydrocarbons can be efficiently generated. Further, since unreacted carbon dioxide is also discharged from the hydrocarbon pre-generating unit 35, a gas having a composition similar to that of biogas can be supplied to the hydrocarbon generating unit 30.

Further, the hydrocarbon pre-generation unit 35 may include a metanation device that produces methane by metanation, and the hydrocarbon generation unit 30 may include a meta-nation device that produces methane by metanation. This makes it possible to efficiently generate a gas containing a high concentration of methane from a gas containing a high concentration of carbon dioxide and a biogas. Therefore, by injecting such a gas into an existing gas conduit, it becomes easy to use it as city gas.

The gas composition at the inlet of the hydrocarbon generation unit 30 when the hydrocarbon pre-generation unit 35 includes a methanation device and the carbon dioxide conversion rate in the hydrocarbon pre-generation unit 35 is 70%, 80% and 90% is as follows. It is a street. The gas composition was _{calculated by a molar ratio based on the reaction formula of CO 2} + 4H ₂ → CH ₄ + 2H ₂ O, and it was assumed that water was removed by the gas-liquid separator 82.

As shown in Table 1, the gas supplied from the hydrocarbon pre-generating unit 35 to the hydrocarbon generating unit 30 includes methane and carbon dioxide as in the case of biogas. Therefore, by supplying the product produced by the hydrocarbon pre-generating unit 35 to the hydrocarbon generating unit 30, a gas having a carbon dioxide concentration closer to that of the biogas than the gas supplied to the hydrocarbon pre-generating unit 35 is carbonized. It can be supplied to the hydrogen generation unit 30. From the viewpoint of approaching the composition of biogas, the carbon dioxide conversion rate of the hydrocarbon pre-producing unit 35 is preferably 80% or more.

The hydrocarbon pre-generation unit 35 includes a single reactor, and the gas supplied to the hydrocarbon generation unit 30 by the single reactor may be brought closer to the composition of biogas. Further, the hydrocarbon pre-generation unit 35 may include a plurality of reactors, and the gas supplied to the hydrocarbon generation unit 30 by the plurality of reactors may be brought close to the composition of biogas. The composition of the biogas is close to that, for example, the methane concentration in the gas produced by the hydrocarbon pre-producing unit 35 and supplied to the hydrocarbon generating unit 30 is -10% with respect to the methane concentration of the biogas. It means that it is within the range of ~ + 10%.

In the present embodiment, the supply amount of hydrogen supplied from the hydrogen supply unit 40 to the hydrocarbon generation unit 30 is controlled by the control unit 60, and is supplied from the hydrogen supply unit 45 to the hydrocarbon pre-generation unit 35. The amount of hydrogen supplied is controlled by the control unit 61. However, hydrogen may be supplied to the hydrocarbon generation unit 30 and the hydrocarbon pre-generation unit 35 from one common hydrogen supply unit. Similarly, the hydrogen supply amount of the hydrogen supply unit 40 and the hydrogen supply unit 45 may be controlled by one common control unit. Further, the carbon dioxide concentration in the gas discharged from the carbon dioxide recovery device 70 tends to have a smaller fluctuation than the carbon dioxide concentration in the biogas. Therefore, the hydrocarbon generation system 1 does not have to include the measurement unit 51 and the control unit 61.

Further, the hydrocarbon generation system 1 according to the present embodiment includes a bioreactor 10 that generates biogas containing methane and carbon dioxide, and a hydrocarbon generation unit 30 that generates hydrocarbons from a raw material containing biogas and hydrogen. Be prepared. As a result, carbon dioxide contained in biogas can be used as a valuable resource without being separated. Therefore, the hydrocarbon generation system 1 does not have to include the measurement unit 50 and the control unit 60.

That is, the hydrocarbon generation system 1 is a hydrocarbon pregeneration that produces a hydrocarbon from a bioreactor 10 that produces a biogas containing methane and carbon dioxide, and a gas having a higher carbon dioxide concentration than the biogas and a raw material containing hydrogen. A unit 35 may be provided. Further, the hydrocarbon generation system 1 may include a hydrocarbon generation unit 30 that generates a hydrocarbon from a raw material containing unreacted carbon dioxide, biogas and hydrogen discharged from the hydrocarbon pre-generation unit 35. Even with such a hydrocarbon generation system 1, carbon dioxide contained in biogas can be used as a valuable resource without being separated. In addition, hydrocarbons can be efficiently generated, and a gas having a composition similar to that of biogas can be supplied to the hydrocarbon generation unit 30.

The entire contents of Japanese Patent Application No. 2020-106800 (application date: June 22, 2020) are incorporated here.

Although some embodiments have been described, it is possible to modify or modify the embodiments based on the above disclosure contents. All the components of the embodiment and all the features described in the claims may be individually extracted and combined as long as they do not contradict each other.

1 Hydrocarbon generation system 10 Bioreactor 30 Hydrocarbon generator 31 Metanation device 32 FT synthesizer 35 Hydrocarbon pre-generation section 50 Measurement section

Claims

A bioreactor that produces biogas containing methane and carbon dioxide,
A hydrocarbon generator that generates hydrocarbons from the raw materials containing biogas and hydrogen,
A measuring unit that measures the concentration of carbon dioxide in the biogas supplied to the hydrocarbon generating unit and the flow rate of the biogas.
Equipped with
A hydrocarbon generation system in which an amount of hydrogen corresponding to the concentration of carbon dioxide measured by the measurement unit and the flow rate of the biogas is supplied to the hydrocarbon generation unit.
The hydrocarbon generation system according to claim 1, wherein the hydrocarbon contains at least one of paraffin and olefin.
The hydrocarbon generation system according to claim 1, wherein the hydrocarbon generation unit includes a metanation apparatus that generates methane by metanation from the biogas and a raw material containing hydrogen.
The hydrocarbon generation unit according to claim 1, wherein the hydrocarbon generation unit includes an FT synthesizer that produces at least one of paraffin and olefin hydrocarbons from the biogas and a raw material containing hydrogen by a Fischer-Tropsch reaction. system.
The hydrocarbon generation unit is an FT synthesizer that produces at least one of paraffin and olefin hydrocarbons from the raw material containing biogas and hydrogen by a Fischer-Tropsch reaction, and an unreacted unit discharged from the FT synthesizer. The hydrocarbon generation system according to claim 1, further comprising a metanation apparatus for producing methane by metanation from a raw material containing carbon dioxide and hydrogen.
The hydrocarbon generator is an FT synthesizer that produces at least one of paraffin and olefin hydrocarbons from the biogas and hydrogen-containing raw materials by Fischer-Tropsch reaction, and meta from the biogas and hydrogen-containing raw materials. The hydrocarbon generation system of claim 1, comprising a metanation apparatus that produces methane by nation.
Further provided with a hydrocarbon pre-generation unit that generates a hydrocarbon from a gas having a higher carbon dioxide concentration than the biogas and a raw material containing hydrogen.
The hydrocarbon generation system according to claim 1, wherein the hydrocarbon generation unit produces a hydrocarbon from a raw material containing unreacted carbon dioxide, biogas and hydrogen discharged from the hydrocarbon pre-generation unit.
The hydrocarbon pre-generation unit includes a meta-nation device that produces methane by meta-nation.
The hydrocarbon generation system according to claim 7, wherein the hydrocarbon generation unit includes a metanation apparatus that produces methane by metanation.
The hydrocarbon generation system according to any one of claims 1 to 8, wherein the bioreactor includes a fermenter, and the fermenter is heated by the reaction heat generated in the hydrocarbon generation unit.