Hydrocarbon generation system and hydrocarbon generation method

Abstract

To provide a hydrocarbon production system and a hydrocarbon production method capable of stably producing a hydrocarbon or producing a high-purity hydrocarbon.SOLUTION: A hydrocarbon production system 1 is equipped with a first reactor 20 for producing a hydrocarbon from a first raw material containing carbon dioxide and hydrogen and a second reactor 40 for producing a hydrocarbon from a second raw material. The hydrocarbon production system 1 is further equipped with a carbon dioxide supply unit 30 for supplying the second reactor 40 with carbon dioxide of the amount corresponding to the amounts of carbon dioxide and hydrogen contained in the first raw material and a hydrogen supply unit 35 for supplying the second reactor 40 with hydrogen of the amount corresponding to the amounts of carbon dioxide and hydrogen contained in the first raw material. The second raw material contains at least one of carbon dioxide and hydrogen supplied from the first reactor 20 and at least one of carbon dioxide supplied from the carbon dioxide supply unit 30 and hydrogen supplied from the hydrogen supply unit 35.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a hydrocarbon production system and a hydrocarbon production method.

Background Art

[0002] Hydrocarbons are widely used as an energy source and a raw material for chemical products, and many of them are produced from fossil fuels. However, when products derived from fossil fuels are burned, the concentration of carbon dioxide in the atmosphere, which is regarded as a cause of global warming, increases. On the other hand, hydrocarbons can be produced from raw materials containing carbon dioxide, and it is expected to suppress carbon dioxide emissions by producing hydrocarbons from carbon dioxide contained in factory exhaust gases and the like.

[0003] However, when producing hydrocarbons from a raw material containing carbon dioxide and hydrogen, the product contains not only the target hydrocarbons but also unreacted carbon dioxide and hydrogen. Therefore, the methane production apparatus disclosed in Patent Document 1 includes a first methanation reactor that produces methane from a gas containing hydrogen and carbon dioxide, and a second methanation reactor that produces methane from the substances remaining in the first methanation reactor. Further, the reaction gas flowing into the first methanation reactor is bypassed and made to flow into the second methanation reactor so that the first methanation reactor approaches a chemical equilibrium state in accordance with fluctuations in the reaction gas flowing into the first methanation reactor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the methane production apparatus of Patent Document 1, methane is produced from the substances remaining in the first methanation reactor, and the reaction process is made multi-stage to improve the production efficiency of methane. However, due to fluctuations in the pressure at the inlet of the first methanation reactor and deviations in the valve opening degrees for supplying each raw material, the ratio of carbon dioxide to hydrogen supplied to the first methanation reactor may vary. In conventional methane production apparatuses, such ratio fluctuations cannot be suppressed, so there is a possibility that hydrocarbons produced in the second methanation reactor cannot be obtained stably or with high purity.

[0006] Therefore, an object of the present disclosure is to provide a hydrocarbon production system and a hydrocarbon production method capable of stably or highly purely producing hydrocarbons.

Means for Solving the Problems

[0007] The hydrocarbon production system according to the present disclosure includes a first reactor that produces hydrocarbons from a first raw material containing carbon dioxide and hydrogen, and a second reactor that produces hydrocarbons from a second raw material. The hydrocarbon production system includes a carbon dioxide supply unit that supplies an amount of carbon dioxide to the second reactor according to the amounts of carbon dioxide and hydrogen contained in the first raw material. The hydrocarbon production system includes a hydrogen supply unit that supplies an amount of hydrogen to the second reactor according to the amounts of carbon dioxide and hydrogen contained in the first raw material. The second raw material includes at least one of carbon dioxide and hydrogen supplied from the first reactor, and at least one of carbon dioxide supplied from the carbon dioxide supply unit and hydrogen supplied from the hydrogen supply unit.

[0008] The hydrocarbon production system further includes a carbon dioxide concentration measurement unit that measures the concentration of carbon dioxide contained in the first raw material, and the amount of carbon dioxide contained in the first raw material may be the concentration of carbon dioxide measured by the carbon dioxide concentration measurement unit.

[0009] The hydrocarbon generation system further includes a hydrogen concentration measurement unit that measures the concentration of hydrogen contained in the first raw material, and the amount of hydrogen contained in the first raw material may be the concentration of hydrogen measured by the hydrogen concentration measurement unit.

[0010] The hydrocarbon generation system further includes a carbon dioxide flow rate measurement unit that measures the flow rate of carbon dioxide contained in the first raw material, and the amount of carbon dioxide contained in the first raw material may be the flow rate of carbon dioxide measured by the carbon dioxide flow rate measurement unit.

[0011] The hydrocarbon generation system further includes a hydrogen flow rate measurement unit that measures the flow rate of hydrogen contained in the first raw material, and the amount of hydrogen contained in the first raw material may be the flow rate of hydrogen measured by the hydrogen flow rate measurement unit.

[0012] At least one of the carbon dioxide supplied by the carbon dioxide supply unit and the hydrogen supplied by the hydrogen supply unit may be supplied to the second reactor according to at least one of the temperature and pressure in the first reactor.

[0013] The hydrocarbons produced in the first reactor and the second reactor may contain linear hydrocarbons having 2 or more carbon atoms.

[0014] The hydrocarbons produced in the first reactor and the second reactor may contain methane.

[0015] The hydrocarbon production method according to the present disclosure includes a first reaction step of producing hydrocarbons from a first raw material containing carbon dioxide and hydrogen in a first reactor, and a second reaction step of producing hydrocarbons from a second raw material in a second reactor. The hydrocarbon production method includes a carbon dioxide supply step of supplying an amount of carbon dioxide to the second reactor according to the amounts of carbon dioxide and hydrogen contained in the first raw material. The hydrocarbon production method includes a hydrogen supply step of supplying an amount of hydrogen to the second reactor according to the amounts of carbon dioxide and hydrogen contained in the first raw material. The second raw material includes at least one of carbon dioxide and hydrogen supplied from the first reactor, and at least one of carbon dioxide supplied in the carbon dioxide supply step and hydrogen supplied in the hydrogen supply step.

Advantages of the Invention

[0016] According to the present disclosure, it is possible to provide a hydrocarbon production system and a hydrocarbon production method capable of stably or highly pure producing hydrocarbons.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0018] Hereinafter, several exemplary embodiments will be described with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the sake of explanation and may differ from the actual ratios.

[0019] [First Embodiment] First, the hydrocarbon generation system 1 according to the first embodiment will be described with reference to FIG. 1. As shown in FIG. 1, the hydrocarbon generation system 1 according to the present embodiment includes a first reactor 20, a second carbon dioxide supply unit 30 (carbon dioxide supply unit), a second hydrogen supply unit 35 (hydrogen supply unit), and a second reactor 40. The hydrocarbon generation system 1 may further include a first carbon dioxide supply unit 10, a first hydrogen supply unit 13, a carbon dioxide concentration measurement unit Q1, a hydrogen concentration measurement unit Q2, a pressure measurement unit P, a temperature measurement unit T, and a control unit 50.

[0020] The first carbon dioxide supply unit 10 supplies carbon dioxide to the first reactor 20. The first carbon dioxide supply unit 10 includes a carbon dioxide supply source 11 and a flow rate adjustment unit 12. The carbon dioxide supply source 11 may include, for example, a carbon dioxide recovery unit that recovers carbon dioxide discharged from a carbon dioxide generation source such as a power plant and a factory. By using the carbon dioxide recovered from the carbon dioxide generation source as a raw material for hydrocarbons, the amount of carbon dioxide released into the atmosphere can be reduced, and useful hydrocarbons can be produced. Also, if hydrocarbons can be produced using carbon dioxide as a raw material, the use of petroleum, which is a finite resource, can also be reduced. The carbon dioxide recovery unit can recover carbon dioxide, for example, by chemical absorption method, pressure swing adsorption method, temperature swing adsorption method, membrane separation concentration method, or a combination thereof. Note that the carbon dioxide supply source 11 is not limited to the above-described form, and may be, for example, a tank containing carbon dioxide. The flow rate adjustment unit 12 may include, for example, an electromagnetic valve, and the supply amount of carbon dioxide supplied from the first carbon dioxide supply unit 10 to the first reactor 20 may be adjusted by opening and closing the electromagnetic valve.

[0021] The first hydrogen supply unit 13 supplies hydrogen to the first reactor 20. The first hydrogen supply unit 13 includes a hydrogen supply source 14 and a flow rate adjustment unit 15. The hydrogen supply source 14 may be, for example, a tank containing hydrogen or the like. The hydrogen may be obtained by electrolyzing water using renewable energy such as sunlight, wind power, and hydraulic power. By using such hydrogen, the carbon dioxide emission amount of the entire hydrocarbon generation system 1 can be reduced. The flow rate adjustment unit 15 may include, for example, an electromagnetic valve, and the supply amount of hydrogen supplied from the first hydrogen supply unit 13 to the first reactor 20 may be adjusted by opening and closing the electromagnetic valve.

[0022] Note that although the carbon dioxide supplied from the first carbon dioxide supply unit 10 and the hydrogen supplied from the first hydrogen supply unit 13 are used as the first raw material, the hydrocarbon generation system 1 according to the present embodiment is not limited to such a form. For example, a first raw material in which carbon dioxide and hydrogen are mixed may be stored in a tank, and the first raw material may be supplied from the tank to the first reactor 20.

[0023] The ratio of the amount of hydrogen to carbon dioxide in the first raw material can be set as appropriate. For example, the molar ratio may be 1 or more, 2 or more, 3 or more, 3.5 or more, or 4 or more. Also, the ratio of the amount of hydrogen to carbon dioxide in the first raw material may be less than 8, less than 6, less than 5, less than 4.5, or less than 4, for example, in terms of molar ratio. In the case of the methanation reaction, the ratio of the amount of hydrogen to carbon dioxide in the first raw material may be 4, which is the stoichiometric ratio.

[0024] The first raw material containing carbon dioxide and hydrogen is supplied to the first reactor 20 via the first flow path 16. The first flow path 16 is provided with a carbon dioxide concentration measurement unit Q1, a hydrogen concentration measurement unit Q2, a compressor 17, a heat exchanger 18, a pressure measurement unit P, and a temperature measurement unit T.

[0025] The carbon dioxide concentration measurement unit Q1 measures the concentration of carbon dioxide contained in the first raw material. By including the carbon dioxide concentration measurement unit Q1 in the hydrocarbon production system 1, the amount of carbon dioxide in the first raw material can be accurately grasped. A signal regarding the concentration of carbon dioxide is sent, for example, from the carbon dioxide concentration measurement unit Q1 to the control unit 50. The carbon dioxide concentration measurement unit Q1 is not particularly limited as long as it can measure the concentration of carbon dioxide, and may include a known carbon dioxide concentration meter. The carbon dioxide concentration measurement unit Q1 may include a gas chromatograph.

[0026] The hydrogen concentration measurement unit Q2 measures the concentration of hydrogen contained in the first raw material. By including the hydrogen concentration measurement unit Q2 in the hydrocarbon production system 1, the amount of hydrogen in the first raw material can be accurately grasped. A signal regarding the concentration of hydrogen is sent, for example, from the hydrogen concentration measurement unit Q2 to the control unit 50. The hydrogen concentration measurement unit Q2 is not particularly limited as long as it can measure the concentration of hydrogen, and may include a known hydrogen concentration meter. The hydrogen concentration measurement unit Q2 may include a gas chromatograph.

[0027] In addition, in the present embodiment, an example in which the hydrocarbon production system 1 includes the carbon dioxide concentration measurement unit Q1 and the hydrogen concentration measurement unit Q2 is described. However, the hydrocarbon production system 1 is not limited to such an example, and may include either one of the carbon dioxide concentration measurement unit Q1 or the hydrogen concentration measurement unit Q2. Further, the hydrocarbon production system 1 may include one concentration measurement unit that measures the concentrations of carbon dioxide and hydrogen.

[0028] The compressor 17 compresses the first raw material. By compressing the first raw material and supplying it to the first reactor 20, the pressure inside the first reactor 20 can be adjusted to a pressure suitable for producing hydrocarbons.

[0029] The heat exchanger 18 heats the first raw material. By heating the first raw material and supplying it to the first reactor 20, the temperature inside the first reactor 20 can be adjusted to a temperature suitable for hydrocarbon production. The heat exchanger 18 exchanges the heat of the first raw material supplied to the first reactor 20 with the heat of the product gas generated in the first reactor 20. Thereby, a hydrocarbon production system 1 with excellent energy efficiency can be provided. Note that since the heat exchanger 18 only needs to be able to heat the first raw material, it is not limited to the heat exchanger as described above and may be a heater.

[0030] The pressure measurement unit P measures the pressure inside the first reactor 20. A signal regarding the pressure inside the first reactor 20 is sent from the pressure measurement unit P to the control unit 50, for example. In the hydrocarbon production system 1 according to the present embodiment, the pressure measurement unit P is provided in the first flow path 16, but the position where the pressure measurement unit P is provided is not particularly limited and may be provided in the first reactor 20. The type of the pressure measurement unit P is not particularly limited as long as it can measure the pressure inside the first reactor 20 and may include a known pressure gauge.

[0031] The temperature measurement unit T measures the temperature inside the first reactor 20. A signal regarding the temperature inside the first reactor 20 is sent from the temperature measurement unit T to the control unit 50, for example. In the hydrocarbon production system 1 according to the present embodiment, the temperature measurement unit T is provided in the first flow path 16, but the position where the temperature measurement unit T is provided is not particularly limited and may be provided in the first reactor 20. The type of the temperature measurement unit T is not particularly limited as long as it can measure the temperature inside the first reactor 20 and may include a known thermometer.

[0032] The first reactor 20 produces hydrocarbons from a first raw material containing carbon dioxide and hydrogen. In the first reactor 20, for example, a catalyst is disposed in the flow path through which the first raw material passes, and hydrocarbons are produced when the first raw material contacts the catalyst. The reaction conditions in the first reactor 20 are not particularly limited. For example, the reaction temperature is 200°C to 400°C, and the pressure is 0.1 MPa to 2 MPa. The hydrocarbons preferably contain straight-chain hydrocarbons having 2 or more carbon atoms. The hydrocarbons preferably also contain methane. 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, for example, a methanation reaction and a Fischer-Tropsch reaction.

[0033] 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 with a high methane concentration can be obtained. Methane can be directly used as an energy source in a factory or directly supplied as town gas. For the methanation reaction, a known reactor including, for example, a multitubular reactor such as a shell-and-tube type reactor may be used.

[0034] The catalyst used in the methanation reaction is not particularly limited as long as it can produce methane. For example, 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 of the whole catalyst, and more preferably 10% by mass or more. When containing nickel as an active ingredient, the content of the active ingredient is preferably 10% by mass or more of the whole catalyst, and when containing ruthenium as an active ingredient, the content of the active ingredient is preferably 0.5% by mass or more of the whole catalyst. From the viewpoints of cost and high methane selectivity, a nickel catalyst is preferably used in the methanation reaction.

[0035] In the Fischer-Tropsch reaction, hydrocarbons containing straight-chain hydrocarbons having 2 or more carbon atoms can be produced from a raw material containing carbon dioxide and hydrogen. Further, hydrocarbons of at least one of paraffin and olefin can be produced from a raw material containing carbon dioxide and hydrogen. At least one of paraffin and olefin preferably contains hydrocarbons having 1 to 4 carbon atoms. Examples of paraffins 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. The product produced by the Fischer-Tropsch reaction usually contains a plurality of types of hydrocarbons. Further, the product produced by the Fischer-Tropsch reaction may contain compounds other than those described above. For the Fischer-Tropsch reaction, a known reactor including, for example, a multitubular reactor such as a shell and tube type reactor, a fluidized bed reactor, or a slurry bed reactor may be used.

[0036] The catalyst used in the Fischer-Tropsch reaction is not particularly limited as long as it can produce straight-chain hydrocarbons having 2 or more carbon atoms, and known catalysts such as iron catalysts or cobalt catalysts can be used. Iron catalysts can mainly produce light hydrocarbons, and cobalt catalysts can mainly produce heavy hydrocarbons containing wax. Further, iron catalysts can mainly produce olefins and paraffins, and cobalt catalysts can mainly produce paraffins. Note that an iron catalyst is a catalyst containing iron as an active ingredient, and a 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. An iron catalyst may be used in the Fischer-Tropsch reaction. Thereby, light olefins (lower olefins) that can also be used as raw materials for plastics can be produced.

[0037] The product gas generated in the first reactor 20 contains not only the target hydrocarbon but also water and at least one of unreacted carbon dioxide and hydrogen. The product gas generated in the first reactor 20 is supplied to the second reactor 40, and hydrocarbons are generated in the second reactor 40 from unreacted carbon dioxide and hydrogen. A heat exchanger 18, a cooler 22, a gas-liquid separator 23, a product gas flow rate measurement unit F1, and a heat exchanger 24 are provided in a second flow path 21 connecting the first reactor 20 and the second reactor 40. Further, carbon dioxide is supplied to the second flow path 21 from a second carbon dioxide supply unit 30, and hydrogen is supplied from a second hydrogen supply unit 35.

[0038] As described above, the heat exchanger 18 exchanges the heat of the first raw material supplied to the first reactor 20 with the heat of the product gas generated in the first reactor 20. That is, the heat exchanger 18 cools the product gas generated in the first reactor 20.

[0039] The cooler 22 further cools the product gas cooled by the heat exchanger 18. Thereby, the water vapor in the product gas generated in the first reactor 20 can be more reliably condensed.

[0040] The gas-liquid separator 23 removes the moisture contained in the product gas generated in the first reactor 20. By removing the moisture in the product gas, the chemical reaction can proceed in the direction of hydrocarbon generation, so that the hydrocarbon generation efficiency in the second reactor 40 can be improved.

[0041] The product gas flow measurement unit F1 measures the flow rate of the product gas generated in the first reactor 20. By measuring the flow rate of the product gas, the ratio of carbon dioxide to hydrogen in the product gas can be calculated from the amounts of hydrogen and carbon dioxide supplied to the first reactor 20 and the flow rate of the product gas. Thereby, the amounts of carbon dioxide and hydrogen supplied to the second reactor 40 can be calculated more accurately. A signal regarding the flow rate of the product gas is sent, for example, from the product gas flow measurement unit F1 to the control unit 50. The product gas flow measurement unit F1 is not particularly limited as long as it can measure the flow rate of the product gas, and may include a known flow meter. Note that the hydrocarbon generation system 1 may be provided with a concentration measurement unit that measures the concentration of either carbon dioxide or hydrogen in the product gas instead of the product gas flow measurement unit F1. The concentration measurement unit can use the same one as the carbon dioxide concentration measurement unit Q1 or the hydrogen concentration measurement unit Q2.

[0042] The heat exchanger 24 heats the second raw material. By heating the second raw material and supplying it to the second reactor 40, the temperature inside the second reactor 40 can be adjusted to a temperature suitable for generating hydrocarbons. The heat exchanger 24 exchanges the heat of the second raw material supplied to the second reactor 40 with the heat of the product gas generated in the second reactor 40. Thereby, a hydrocarbon generation system 1 with excellent energy efficiency can be provided. Note that the heat exchanger 24 is not limited to the heat exchanger as described above as long as it can heat the second raw material, and may be a heater.

[0043] The second carbon dioxide supply unit 30 supplies an amount of carbon dioxide to the second reactor 40 according to the amounts of carbon dioxide and hydrogen contained in the first raw material. The amount of carbon dioxide contained in the first raw material may be, for example, the concentration of carbon dioxide measured by the carbon dioxide concentration measurement unit Q1. Also, the amount of hydrogen contained in the first raw material may be, for example, the concentration of hydrogen measured by the hydrogen concentration measurement unit Q2. That is, the second carbon dioxide supply unit 30 may supply an amount of carbon dioxide according to the carbon dioxide measured by the carbon dioxide concentration measurement unit Q1 and the hydrogen concentration measured by the hydrogen concentration measurement unit Q2. By supplying an amount of carbon dioxide according to the concentrations of carbon dioxide and hydrogen to the second reactor 40, a more appropriate amount of carbon dioxide can be supplied to the second reactor 40.

[0044] The second carbon dioxide supply unit 30 includes a carbon dioxide supply source 31 and a flow rate adjustment unit 32, similar to the first carbon dioxide supply unit 10. The carbon dioxide supply source 31 may employ the same one as the carbon dioxide supply source 11. The first carbon dioxide supply unit 10 and the second carbon dioxide supply unit 30 may include a common carbon dioxide supply source. The flow rate adjustment unit 32 may include, for example, an electromagnetic valve, and the supply amount of carbon dioxide supplied from the second carbon dioxide supply unit 30 to the second reactor 40 may be adjusted by opening and closing the electromagnetic valve.

[0045] The second hydrogen supply unit 35 supplies an amount of hydrogen to the second reactor 40 according to the amounts of carbon dioxide and hydrogen contained in the first raw material. The amount of carbon dioxide contained in the first raw material may be, for example, the concentration of carbon dioxide measured by the carbon dioxide concentration measurement unit Q1. Also, the amount of hydrogen contained in the first raw material may be, for example, the concentration of hydrogen measured by the hydrogen concentration measurement unit Q2. That is, the second hydrogen supply unit 35 may supply an amount of hydrogen according to the carbon dioxide measured by the carbon dioxide concentration measurement unit Q1 and the hydrogen concentration measured by the hydrogen concentration measurement unit Q2. By supplying an amount of hydrogen according to the concentrations of carbon dioxide and hydrogen to the second reactor 40, a more appropriate amount of hydrogen can be supplied to the second reactor 40.

[0046] The second hydrogen supply section 35 includes a hydrogen supply source 36 and a flow rate adjustment section 37. As the hydrogen supply source 36, the same one as the hydrogen supply source 14 may be adopted. The first hydrogen supply section 13 and the second hydrogen supply section 35 may include one common hydrogen supply source. The flow rate adjustment section 37 may include, for example, a solenoid valve, and the supply amount of hydrogen supplied from the second hydrogen supply section 35 to the second reactor 40 may be adjusted by opening and closing the solenoid valve.

[0047] At least one of the carbon dioxide supplied by the second carbon dioxide supply section 30 and the hydrogen supplied by the second hydrogen supply section 35 may be supplied to the second reactor 40 according to at least one of the temperature and pressure in the first reactor 20. Thereby, a second raw material having a composition suitable for the reaction in the second reactor 40 can be supplied to the second reactor 40. In the hydrocarbon production system 1 according to the present embodiment, the temperature is measured by the temperature measurement section T, and the pressure is measured by the pressure measurement section P.

[0048] The second reactor 40 generates hydrocarbons from the second raw material. The second raw material includes at least one of carbon dioxide and hydrogen supplied from the first reactor 20, and at least one of carbon dioxide supplied from the second carbon dioxide supply section 30 and hydrogen supplied from the second hydrogen supply section 35. As the second reactor 40, the same one as the first reactor 20 can be adopted, and hydrocarbons can be generated by a methanation reaction, a Fischer-Tropsch reaction, or the like. The second reactor 40 may generate hydrocarbons using different reaction methods in the first reactor 20 and the second reactor 40.

[0049] The product gas generated in the second reactor 40 and containing hydrocarbons is discharged from the second reactor 40 through the third flow path 41. A heat exchanger 24, a back pressure valve 42, a cooler 43, and a gas-liquid separator 44 are provided in the third flow path 41.

[0050] As described above, the heat exchanger 24 exchanges the heat of the second raw material supplied to the second reactor 40 with the heat of the product gas generated in the second reactor 40. That is, the heat exchanger 24 cools the product gas generated in the second reactor 40.

[0051] The back pressure valve 42 adjusts the opening degree of the valve to adjust the pressures in the first reactor 20 and the second reactor 40 within a predetermined range.

[0052] The cooler 43 further cools the product gas cooled by the heat exchanger 24. Thereby, the water vapor in the product gas generated in the second reactor 40 can be more surely condensed.

[0053] The gas-liquid separator 44 removes the moisture contained in the product gas generated in the second reactor 40. By removing the moisture in the product gas, high-purity hydrocarbons can be obtained.

[0054] The control unit 50 controls the flow rate of the carbon dioxide supplied from the second carbon dioxide supply unit 30. Further, the control unit 50 controls the flow rate of the hydrogen supplied from the second hydrogen supply unit 35. The control unit 50 may calculate the supply amount of the carbon dioxide supplied by the second carbon dioxide supply unit 30 and the supply amount of the hydrogen supplied by the second hydrogen supply unit 35 based on a signal generated by at least one element selected from the group consisting of the carbon dioxide concentration measurement unit Q1, the hydrogen concentration measurement unit Q2, the pressure measurement unit P, the temperature measurement unit T, and the product gas flow rate measurement unit F1. The control unit 50 adjusts, for example, the flow rate of the carbon dioxide supplied from the second carbon dioxide supply unit 30 by the flow rate adjustment unit 32. Further, the control unit 50 adjusts, for example, the flow rate of the hydrogen supplied from the second hydrogen supply unit 35 by the flow rate adjustment unit 37.

[0055] The control unit 50 may include a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU can read a program stored in the ROM and execute instructions such as arithmetic operations and control according to the program. The program may include, for example, a process of calculating the supply amounts of carbon dioxide and hydrogen supplied to the second reactor 40 from the amounts of carbon dioxide and hydrogen contained in the first raw material. 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 carbon dioxide concentration measurement unit Q1, the hydrogen concentration measurement unit Q2, the pressure measurement unit P, the temperature measurement unit T, the generated gas flow rate measurement unit F1, etc., and the CPU can read the information stored in the RAM and use it for processes such as arithmetic operations.

[0056] When the product generated in the second reactor 40 contains multiple types of hydrocarbons, the hydrocarbon production system 1 may be provided with a separation device that separates the hydrocarbons according to their chemical structure by fractional distillation or the like. The separation device may include at least one separation column such as a demethanizer, a deethanizer, a deethylene column, a depropanizer, a depropylene column, a debutanizer, and a debutene column. By these separation columns, multiple types of hydrocarbons can be separated according to their chemical structures such as methane, ethane, ethylene, propane, propylene, butane, and butene.

[0057] [Second Embodiment] Next, the hydrocarbon production system 1 according to the second embodiment will be described with reference to FIG. 2. The hydrocarbon production system 1 according to the present embodiment includes a carbon dioxide flow rate measurement unit F2 instead of the carbon dioxide concentration measurement unit Q1, and a hydrogen flow rate measurement unit F3 instead of the hydrogen concentration measurement unit Q2. Except for the above, the hydrocarbon production system 1 according to the present embodiment has the same configuration as the hydrocarbon production system 1 according to the first embodiment.

[0058] The carbon dioxide flow rate measurement unit F2 measures the flow rate of carbon dioxide contained in the first raw material. By providing the hydrocarbon generation system 1 with the carbon dioxide flow rate measurement unit F2, the amount of carbon dioxide in the first raw material can be accurately grasped. A signal regarding the flow rate of carbon dioxide is sent, for example, from the carbon dioxide flow rate measurement unit F2 to the control unit 50. The carbon dioxide flow rate measurement unit F2 is not particularly limited as long as it can measure the flow rate of carbon dioxide, and may include a known flow meter.

[0059] The hydrogen flow rate measurement unit F3 measures the flow rate of hydrogen contained in the first raw material. By providing the hydrocarbon generation system 1 with the hydrogen flow rate measurement unit F3, the amount of hydrogen in the first raw material can be accurately grasped. A signal regarding the concentration of hydrogen is sent, for example, from the hydrogen flow rate measurement unit F3 to the control unit 50. The hydrogen flow rate measurement unit F3 is not particularly limited as long as it can measure the flow rate of hydrogen, and may include a known flow meter.

[0060] In this embodiment, an example in which the hydrocarbon generation system 1 includes the carbon dioxide flow rate measurement unit F2 and the hydrogen flow rate measurement unit F3 is described. However, the hydrocarbon generation system 1 is not limited to such an example, and may include either one of the carbon dioxide flow rate measurement unit F2 or the hydrogen flow rate measurement unit F3. Furthermore, the hydrocarbon generation system 1 may further include at least one of the carbon dioxide concentration measurement unit Q1 and the hydrogen concentration measurement unit Q2.

[0061] Similar to the first embodiment, the second carbon dioxide supply unit 30 supplies an amount of carbon dioxide corresponding to the amounts of carbon dioxide and hydrogen contained in the first raw material to the second reactor 40. The amount of carbon dioxide contained in the first raw material may be, for example, the flow rate of carbon dioxide measured by the carbon dioxide flow rate measurement unit F2. Also, the amount of hydrogen contained in the first raw material may be, for example, the flow rate of hydrogen measured by the hydrogen flow rate measurement unit F3. Therefore, the second carbon dioxide supply unit 30 may supply an amount of carbon dioxide corresponding to the carbon dioxide measured by the carbon dioxide flow rate measurement unit F2 and the hydrogen flow rate measured by the hydrogen flow rate measurement unit F3. By supplying an amount of carbon dioxide corresponding to the flow rates of carbon dioxide and hydrogen to the second reactor 40, a more appropriate amount of carbon dioxide can be supplied to the second reactor 40.

[0062] Similarly, the second hydrogen supply unit 35 supplies an amount of hydrogen corresponding to the amounts of carbon dioxide and hydrogen contained in the first raw material to the second reactor 40. The amount of carbon dioxide contained in the first raw material may be, for example, the flow rate of carbon dioxide measured by the carbon dioxide flow rate measurement unit F2. Also, the amount of hydrogen contained in the first raw material may be, for example, the flow rate of hydrogen measured by the hydrogen flow rate measurement unit F3. Therefore, the second hydrogen supply unit 35 may supply an amount of hydrogen corresponding to the carbon dioxide measured by the carbon dioxide flow rate measurement unit F2 and the hydrogen flow rate measured by the hydrogen flow rate measurement unit F3. By supplying an amount of hydrogen corresponding to the flow rates of carbon dioxide and hydrogen to the second reactor 40, a more appropriate amount of hydrogen can be supplied to the second reactor 40.

[0063] As described above, in the present disclosure, the hydrocarbon production system 1 and the hydrocarbon production method according to the first embodiment and the second embodiment have been described. That is, the hydrocarbon production system 1 includes a first reactor 20 that produces hydrocarbons from a first raw material containing carbon dioxide and hydrogen, and a second reactor 40 that produces hydrocarbons from a second raw material. The hydrocarbon production system 1 includes a second carbon dioxide supply unit 30 that supplies an amount of carbon dioxide corresponding to the amounts of carbon dioxide and hydrogen contained in the first raw material to the second reactor 40. The hydrocarbon production system 1 includes a second hydrogen supply unit 35 that supplies an amount of hydrogen corresponding to the amounts of carbon dioxide and hydrogen contained in the first raw material to the second reactor 40. The second raw material includes at least one of carbon dioxide and hydrogen supplied from the first reactor 20, and at least one of carbon dioxide supplied from the second carbon dioxide supply unit 30 and hydrogen supplied from the second hydrogen supply unit 35.

[0064] The hydrocarbon production method includes a first reaction step of producing hydrocarbons from a first raw material containing carbon dioxide and hydrogen in the first reactor 20, and a second reaction step of producing hydrocarbons from a second raw material in the second reactor 40. The hydrocarbon production method includes a carbon dioxide supply step of supplying an amount of carbon dioxide corresponding to the amounts of carbon dioxide and hydrogen contained in the first raw material to the second reactor 40. The hydrocarbon production method includes a hydrogen supply step of supplying an amount of hydrogen corresponding to the amounts of carbon dioxide and hydrogen contained in the first raw material to the second reactor 40. The second raw material includes at least one of carbon dioxide and hydrogen supplied from the first reactor 20, and at least one of carbon dioxide supplied in the carbon dioxide supply step and hydrogen supplied in the hydrogen supply step.

[0065] The hydrocarbon production system 1 according to this embodiment includes a first reactor 20 that produces hydrocarbons from a first raw material containing carbon dioxide and hydrogen, and a second reactor 40 that produces hydrocarbons from a second raw material. Therefore, carbon dioxide and hydrogen that were unreacted in the first reactor 20 are supplied as raw materials to the second reactor 40, and higher-purity hydrocarbons can be obtained. However, due to fluctuations in the pressure at the inlet of the first reactor 20 and deviations in the valve openings of the flow rate adjustment units 12 and 15, the ratio of carbon dioxide to hydrogen supplied to the first reactor 20 may vary. Also, when separating the water contained in the product gas generated in the first reactor 20, carbon dioxide dissolves in the water, and the ratio of carbon dioxide to hydrogen supplied to the second reactor 40 may deviate from the ideal ratio. In such a case, the conversion rate in the first reactor 20 may decrease below the assumption, and the concentration of hydrocarbons in the product gas generated in the second reactor 40 may fall below the desired value.

[0066] However, the hydrocarbon production system 1 according to this embodiment includes a second carbon dioxide supply unit 30 that supplies an amount of carbon dioxide to the second reactor 40 according to the amounts of carbon dioxide and hydrogen contained in the first raw material. The hydrocarbon production system 1 also includes a second hydrogen supply unit 35 that supplies an amount of hydrogen to the second reactor 40 according to the amounts of carbon dioxide and hydrogen contained in the first raw material. Thereby, even when the ratio of carbon dioxide to hydrogen in the first raw material supplied to the first reactor 20 deviates from the desired range, the second carbon dioxide supply unit 30 and the second hydrogen supply unit 35 can complement carbon dioxide and hydrogen to the second reactor 40 respectively. Therefore, the ratio of carbon dioxide to hydrogen in the second raw material can be adjusted to the ideal ratio. Thereby, the hydrocarbon concentration in the product gas generated in the second reactor 40 is adjusted to be within a predetermined range. Therefore, according to the present disclosure, it is possible to provide a hydrocarbon production system 1 and a hydrocarbon production method capable of stably or highly purely producing hydrocarbons.

[0067] In addition, the second raw material contains a large amount of hydrocarbons produced in the first reactor 20, and the amount of hydrocarbons produced in the second reactor 40 tends to be less than the amount of hydrocarbons produced in the first reactor 20. That is, since the amount of hydrocarbons produced in the second reactor 40 is not large as a whole for the hydrocarbon production system 1, control for stably or highly pure producing hydrocarbons is relatively easy.

[0068] According to the retail delivery supply terms of Osaka Gas Co., Ltd. (implemented on November 13, 2019), the composition of the methane-containing gas to be received is required to have hydrogen of 4% by volume or less and carbon dioxide of 0.5% by volume or less. The results of calculating the supply amounts of raw materials necessary for producing such a gas in the first reactor 20 and the second reactor 40 are shown in FIG. 3. Specifically, in the range where the ratio of hydrogen to carbon dioxide (H2 / CO2 ratio) in the first raw material is from 3.6 to 4.4, the H2 / CO2 ratio of the second raw material at which a methane-containing gas having the above composition can be produced in the second reactor 40 was calculated. The reaction conditions of the first reactor 20 and the second reactor 40 are set at a temperature of 325°C and a pressure of 0.7 MPaG.

[0069] As shown in FIG. 3, it can be seen that a methane-containing gas having the required composition can be produced if the H2 / CO2 ratio of the second raw material is in the range from the upper limit to the lower limit. According to the reaction formula: CO2 + 4H2 → CH4 + 2H2O, 1 mole of methane is produced from 1 mole of carbon dioxide and 4 moles of hydrogen. The reason why the H2 / CO2 ratio of the second raw material is 4 or more is considered to be that the allowable range of hydrogen is 4% by volume or less, while the allowable amount of carbon dioxide is 0.5% by volume or less, and the allowable range is wide.

[0070] Next, the upper and lower limits of the supply amounts of carbon dioxide and hydrogen for generating the methane-containing gas in the second reactor 40 were calculated respectively. The relationships between the H2 / CO2 ratio of the first raw material and the ratio of the supply amount of hydrogen supplied to the second reactor 40 to the supply amount of carbon dioxide supplied to the first reactor 20 are shown in Table 1 and FIG. 4. Also, the relationships between the H2 / CO2 ratio of the first raw material and the ratio of the supply amount of carbon dioxide supplied to the second reactor 40 to the supply amount of carbon dioxide supplied to the first reactor 20 are shown in Table 2 and FIG. 5. Note that the reaction conditions of the first reactor 20 and the second reactor 40 are a temperature of 325°C and a pressure of 0.7 MPaG.

[0071] [Table 1]

[0072] [Table 2]

[0073] As shown in Table 1, Table 2, and FIGS. 3 to 5, it can be seen that by supplying an amount of carbon dioxide or hydrogen corresponding to the amounts of carbon dioxide and hydrogen contained in the first raw material to the second reactor 40, it is possible to generate a methane-containing gas having the above composition. Also, from these results, it can be seen that even when the H2 / CO2 ratio of the first raw material supplied to the first reactor 20 fluctuates, hydrocarbons can be stably or highly purified by supplying carbon dioxide or hydrogen to the second reactor 40.

[0074] In the above embodiment, an example in which the hydrocarbon generation system 1 includes two reactors, the first reactor 20 and the second reactor 40, has been described. However, the hydrocarbon generation system 1 may include three or more reactors. When the hydrocarbon generation system 1 includes three or more reactors, the first-stage reactor may be the first reactor 20 and the second-stage reactor may be the second reactor 40, or the second-stage reactor may be the first reactor 20 and the third-stage reactor may be the second reactor 40.

[0075] Although some embodiments have been described, it is possible to modify or deform the embodiments based on the above disclosure. All the components of the above embodiments and all the features described in the claims may be extracted and combined individually as long as they do not conflict with each other.

[0076] This disclosure can contribute to, for example, Goal 7 of the Sustainable Development Goals (SDGs) led by the United Nations, "Ensure access to affordable, reliable, sustainable and modern energy for all", and Goal 13, "Take urgent action to combat climate change and its impacts".

Explanation of Reference Numerals

[0077] 1 Hydrocarbon generation system 20 First reactor 30 Second carbon dioxide supply unit (carbon dioxide supply unit) 35 Second hydrogen supply unit (hydrogen supply unit) 40 Second reactor Q1 Carbon dioxide concentration measurement unit Q2 Hydrogen concentration measurement unit F2 Carbon dioxide flow rate measurement unit F3 Hydrogen flow rate measurement unit

Claims

1. A first reactor that produces hydrocarbons from a first raw material containing carbon dioxide and hydrogen by a Fischer-Tropsch reaction; A second reactor that produces hydrocarbons from a second raw material by a Fischer-Tropsch reaction; A carbon dioxide supply unit that supplies an amount of carbon dioxide to the second reactor according to the ratio of carbon dioxide to hydrogen in the first raw material supplied to the first reactor; A hydrogen supply unit that supplies an amount of hydrogen to the second reactor according to the ratio of carbon dioxide to hydrogen in the first raw material supplied to the first reactor; Comprising: The second raw material includes at least one of carbon dioxide and hydrogen supplied from the first reactor, and at least one of carbon dioxide supplied from the carbon dioxide supply unit and hydrogen supplied from the hydrogen supply unit; The hydrocarbons produced in the first reactor include hydrocarbons having 2 to 4 carbon atoms produced by contacting the first raw material with an iron catalyst or a cobalt catalyst; A hydrocarbon production system, wherein the hydrocarbons produced in the second reactor include hydrocarbons having 2 to 4 carbon atoms produced by contacting the second raw material with an iron catalyst or a cobalt catalyst.

2. The hydrocarbon production system according to claim 1, further comprising a carbon dioxide concentration measurement unit that measures the concentration of carbon dioxide contained in the first raw material, and the amount of carbon dioxide contained in the first raw material is the concentration of carbon dioxide measured by the carbon dioxide concentration measurement unit.

3. The hydrocarbon production system according to claim 1 or 2, further comprising a hydrogen concentration measurement unit that measures the concentration of hydrogen contained in the first raw material, and the amount of hydrogen contained in the first raw material is the concentration of hydrogen measured by the hydrogen concentration measurement unit.

4. The hydrocarbon production system according to any one of claims 1 to 3, further comprising a carbon dioxide flow rate measurement unit that measures the flow rate of carbon dioxide contained in the first raw material, and the amount of carbon dioxide contained in the first raw material is the flow rate of carbon dioxide measured by the carbon dioxide flow rate measurement unit.

5. The hydrocarbon production system according to any one of claims 1 to 4, further comprising a hydrogen flow rate measurement unit that measures the flow rate of hydrogen contained in the first raw material, and the amount of hydrogen contained in the first raw material is the flow rate of hydrogen measured by the hydrogen flow rate measurement unit.

6. In the hydrocarbon production system according to any one of claims 1 to 5, at least one of carbon dioxide supplied by the carbon dioxide supply unit and hydrogen supplied by the hydrogen supply unit is supplied to the second reactor according to at least one of the temperature and pressure in the first reactor.

7. A first reaction step of producing hydrocarbons in a first reactor by a Fischer-Tropsch reaction from a first raw material containing carbon dioxide and hydrogen; A second reaction step of producing hydrocarbons in a second reactor by a Fischer-Tropsch reaction from a second raw material; A carbon dioxide supply step of supplying an amount of carbon dioxide corresponding to the ratio of carbon dioxide to hydrogen in the first raw material supplied to the first reactor to the second reactor; A hydrogen supply step of supplying an amount of hydrogen corresponding to the ratio of carbon dioxide to hydrogen in the first raw material supplied to the first reactor to the second reactor; comprising The second raw material includes at least one of carbon dioxide and hydrogen supplied from the first reactor, and at least one of carbon dioxide supplied in the carbon dioxide supply step and hydrogen supplied in the hydrogen supply step; The hydrocarbons produced in the first reactor include hydrocarbons having 2 to 4 carbon atoms produced by contacting the first raw material with an iron catalyst or a cobalt catalyst; A hydrocarbon production method, wherein the hydrocarbons produced in the second reactor include hydrocarbons having 2 to 4 carbon atoms produced by contacting the second raw material with an iron catalyst or a cobalt catalyst.

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