Recycling System

Abstract

To provide a recycle system that can recycle carbon dioxide with less electrical energy and reduce the risk of carbon deposition.SOLUTION: A recycle system comprises: a high-temperature gas furnace as a supply source of heat energy in a high-temperature region; an SOEC for co-electrolysis for producing carbon monoxide and hydrogen by co-electrolysis of carbon dioxide and water vapor using the heat energy of the high-temperature gas furnace; and a CO utilization facility arranged to supply carbon monoxide from the SOEC for co-electrolysis and utilizing the carbon monoxide.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a recycling system that reuses carbon dioxide exhausted from factories and the like, reduces carbon dioxide emissions, and utilizes thermal energy in a stepwise manner from a high temperature region to a low temperature region. [Background technology]

[0002] Patent Document 1 discloses a fuel production system including a hydrogen production device that produces hydrogen by endothermic reaction of water vapor, and a hydrocarbon production device that produces hydrocarbons by reacting the produced hydrogen with a gas containing at least a portion of carbon monoxide and carbon dioxide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-108238 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when producing hydrocarbons by reacting carbon dioxide with hydrogen, the carbon dioxide is reduced stepwise to carbon monoxide, and then the carbon monoxide is reduced to hydrocarbons. To obtain carbon monoxide from carbon dioxide, the reaction must be carried out at high temperatures, which requires a lot of electrical energy. In addition, during the process of producing hydrocarbons, carbon may be precipitated from the carbon monoxide (coking phenomenon), which may cause equipment malfunctions, and other risks.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a recycling system that can reuse carbon dioxide with less electrical energy and reduce the risk of carbon precipitation. [Means for solving the problem]

[0006] In order to solve the above problems, the recycling system according to the present disclosure includes: It is the thermal energy contained in water vapor at temperatures between 700℃ and 1000℃. A high-temperature gas-cooled reactor as a source of thermal energy in the high-temperature region; The thermal energy supplied from the high-temperature gas reactor can be used in stages from the high-temperature side to the low-temperature side, and A co-electrolysis SOEC that produces carbon monoxide and hydrogen by co-electrolysis of carbon dioxide and steam using thermal energy from the high-temperature gas reactor. A heat utilization facility having a co-electrolysis facility having the above-mentioned a CO utilization facility that utilizes carbon monoxide and is provided so as to be capable of supplying carbon monoxide from the co-electrolysis SOEC; The heat utilization facility further includes an intermediate heat exchanger that supplies thermal energy of the high temperature region of the high temperature gas reactor, a hydrogen production facility connected to the intermediate heat exchanger via a plurality of lines, and a heat supply steam production facility provided in the CO utilization facility. . Effect of the Invention

[0007] According to the recycling system of the present disclosure, carbon dioxide can be reused with less electrical energy and the risk of carbon deposition can be reduced. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram of a recycling system according to a first embodiment of the present disclosure. [Diagram 2] FIG. 1 is a configuration diagram of a CO2 capture and supply facility according to a first embodiment of the present disclosure. [Diagram 3] FIG. 1 is a diagram of a recycling system according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First Embodiment (Recycling System) Hereinafter, a recycling system 100 according to a first embodiment of the present disclosure will be described with reference to FIGS. The recycle system 100 shown in FIG. 1 is a system that reuses carbon dioxide exhausted from factories and the like, reduces the amount of carbon dioxide emissions, and utilizes thermal energy in stages from a high temperature region to a low temperature region.

[0010] As shown in FIG. 1, the recycling system 100 includes a high-temperature gas reactor 1, an intermediate heat exchanger 2, a hydrogen production facility 3, a co-electrolysis facility 4, a CO utilization facility 5, and a CO2 recovery and supply facility 6.

[0011] The recycling system 100 includes a heat utilization facility 8 that supplies thermal energy to these facilities and devices via a heat medium. In this embodiment, helium and water vapor (water) are used as the heat medium. Each component of the recycle system 100 will be described in detail below.

[0012] (High Temperature Gas Reactor) The HTGR 1 is being developed as a nuclear reactor capable of extracting high-temperature heat with the goal of utilizing nuclear heat for multiple purposes. The HTGR 1 is used as a source of thermal energy in the high-temperature range. In the following, thermal energy contained in water vapor at 700°C or higher and 1000°C or lower will be conceptually referred to as thermal energy in the high temperature region, thermal energy contained in water vapor at 300°C or higher and 700°C or lower will be referred to as thermal energy in the medium temperature region, and thermal energy contained in water vapor at 100°C or higher and 300°C or lower will be referred to as thermal energy in the low temperature region. The thermal energy of the high temperature gas reactor 1 is supplied to other facilities and devices via helium and steam flowing through the heat utilization facility 8.

[0013] The high temperature gas reactor 1 is connected to the intermediate heat exchanger 2 by a first heat exchange line 10 and a second heat exchange line 11. Helium flows from the high temperature gas reactor 1 toward the intermediate heat exchanger 2 through the first heat exchange line 10. Helium flows from the intermediate heat exchanger 2 toward the high temperature gas reactor 1 through the second heat exchange line 11. In this manner, helium circulates between the high temperature gas reactor 1 and the intermediate heat exchanger 2.

[0014] Hereinafter, the helium circulating between the high-temperature gas reactor 1 and the intermediate heat exchanger 2 will be referred to as primary helium. The primary helium enters the high-temperature gas reactor 1, and is directly supplied with thermal energy from the high-temperature region from the high-temperature gas reactor 1. Helium is a thermochemically stable substance, so even if it enters the high-temperature gas reactor 1, it will not become radioactive.

[0015] (Intermediate heat exchanger) The intermediate heat exchanger 2 exchanges heat between the primary helium and helium (hereinafter referred to as secondary helium) that flows through a different flow path from the primary helium. The secondary helium exchanges heat with the primary helium without coming into contact with the HTGR 1, and obtains thermal energy from the high temperature region of the HTGR 1.

[0016] The intermediate heat exchanger 2 is connected to a hydrogen production facility 3, a co-electrolysis facility 4, and a CO utilization facility 5 by supply lines 20.

[0017] The supply line 20 has an upstream supply line 21, a supply header section 22, and a downstream supply line 23. The upstream supply line 21 connects the intermediate heat exchanger 2 and the supply header section 22. The supply header section 22 is provided with a plurality of downstream supply lines 23. Some of the downstream supply lines 23 connect the supply header section 22 and the hydrogen production facility 3, another portion of the downstream supply lines 23 connect the supply header section 22 and the co-electrolysis facility 4, and still another portion of the downstream supply lines 23 connect the supply header section 22 and the CO utilization facility 5. After heat exchange with the primary helium, the secondary helium is supplied to the hydrogen production facility 3, the co-electrolysis facility 4, and the CO utilization facility 5 through the supply line 20.

[0018] (Hydrogen production facility) The hydrogen production facility 3 includes a hydrogen steam production facility 30 and a hydrogen production SOEC (Solid Oxide Electrolysis Cell) 31.

[0019] (Hydrogen steam production equipment) The hydrogen steam production facility 30 is supplied with thermal energy from the high temperature region of the high temperature gas reactor 1 via secondary helium flowing through a supply line 20. The hydrogen steam production facility 30 uses the thermal energy of the high temperature gas reactor 1 to produce high temperature steam.

[0020] The hydrogen steam production facility 30 has a hydrogen steam generator 32, a hydrogen steam preheater 33, and a hydrogen steam superheater 34. The hydrogen steam generator 32 is connected to the hydrogen production SOEC 31 by a hydrogen steam flow path 35. In the hydrogen steam flow path 35, water vapor flows from the hydrogen steam generator 32 toward the hydrogen production SOEC 31. The hydrogen steam preheater 33 and the hydrogen steam superheater 34 are provided in the midstream portion of the hydrogen steam flow path 35. The hydrogen steam preheater 33 is disposed upstream of the hydrogen steam superheater 34.

[0021] (Hydrogen steam generator) The hydrogen steam generator 32 is supplied with thermal energy in the medium temperature range from the hydrogen steam superheater 34. The supply of thermal energy from the hydrogen steam superheater 34 to the hydrogen steam generator 32 will be described later. In addition, water is supplied to the hydrogen steam generator 32 from the outside. The hydrogen steam generator 32 heats water with the thermal energy in the medium temperature range after use in the hydrogen steam superheater 34 to generate steam. The heat after use in the hydrogen steam superheater 34 is supplied from a hydrogen production intermediate line 36, which is in the medium temperature range and is lower than the heat supplied from the downstream supply line 23, and by using this in the hydrogen steam generator 32, the heat of the high temperature gas reactor 1 is used efficiently.

[0022] (Hydrogen steam preheater) The hydrogen steam preheater 33 is supplied with water steam from the hydrogen steam generator 32. The hydrogen steam preheater 33 is also connected to the supply header section 22 by a downstream supply line 23. The hydrogen steam preheater 33 is supplied with secondary helium from the supply header section 22. The hydrogen steam preheater 33 is supplied with thermal energy from the high temperature region of the high temperature gas reactor 1 via the secondary helium.

[0023] (Hydrogen steam superheater) The hydrogen steam superheater 34 is supplied with steam from the hydrogen steam preheater 33. The hydrogen steam superheater 34 is also connected to the supply header section 22 by the downstream supply line 23. Secondary helium is supplied to the hydrogen steam superheater 34 from the supply header section 22. Thermal energy of the high temperature region of the high temperature gas reactor 1 is supplied to the hydrogen steam superheater 34 via the secondary helium. The hydrogen steam superheater 34 further heats the steam by utilizing the thermal energy of the high temperature region contained in the secondary helium. The steam heated by the hydrogen steam superheater 34 contains the thermal energy of the high temperature region of the high temperature gas reactor 1.

[0024] The hydrogen steam superheater 34 is connected to the hydrogen steam generator 32 by a hydrogen production intermediate line 36. After being supplied to the hydrogen steam superheater 34, the thermal energy of the secondary helium is reduced to the medium temperature range. The secondary helium is supplied from the hydrogen steam superheater 34 through the hydrogen production intermediate line 36 to the hydrogen steam generator 32. This secondary helium supplies the hydrogen steam generator 32 with thermal energy in the medium temperature range after being used in the hydrogen steam superheater 34. Therefore, in the hydrogen steam generator 32, thermal energy in the medium temperature range is used to generate steam.

[0025] (SOEC for hydrogen production) The hydrogen production SOEC 31 is supplied with steam from a hydrogen steam superheater 34. The hydrogen production SOEC 31 also has a hydrogen production hydrogen electrode 31a and an oxygen electrode 31b. An electrolysis voltage is applied between the hydrogen production hydrogen electrode 31a and the hydrogen production oxygen electrode 31b, and electrical energy is supplied to the hydrogen production SOEC 31. The hydrogen production SOEC 31 electrolyzes the steam using thermal energy contained in the steam in the high temperature region of the high temperature gas reactor 1 to produce hydrogen. The hydrogen production SOEC 31 is connected to the CO utilization facility 5 by a recovery line 71. The hydrogen produced by the hydrogen production SOEC 31 is supplied to the CO utilization facility 5 through the recovery line 71. The hydrogen production SOEC 31 produces oxygen during hydrogen production. The oxygen produced by the hydrogen production SOEC 31 is discharged to the outside.

[0026] (Co-electrolysis equipment) The co-electrolysis facility 4 includes a steam production facility 40 for co-electrolysis and an SOEC 41 for co-electrolysis.

[0027] (Steam production equipment for co-electrolysis) The steam production facility 40 for co-electrolysis is supplied with thermal energy from the high temperature region of the high temperature gas reactor 1 via secondary helium flowing through a supply line 20. The steam production facility 40 for co-electrolysis uses the thermal energy of the high temperature gas reactor 1 to produce high temperature steam.

[0028] The co-electrolysis steam production facility 40 includes a co-electrolysis steam generator 42, a co-electrolysis steam preheater 43, and a co-electrolysis steam superheater 44. The co-electrolysis steam generator 42 is connected to the co-electrolysis SOEC 41 by a co-electrolysis steam flow path 45. In the co-electrolysis steam flow path 45, water vapor flows from the co-electrolysis steam generator 42 toward the co-electrolysis SOEC 41. The co-electrolysis steam preheater 43 and the co-electrolysis steam superheater 44 are provided in a midstream portion of the co-electrolysis steam flow path 45. The co-electrolysis steam preheater 43 is disposed upstream of the co-electrolysis steam superheater 44.

[0029] (Steam generator for co-electrolysis) The co-electrolysis steam generator 42 is supplied with thermal energy in the medium temperature range from the co-electrolysis steam superheater 44. The supply of thermal energy from the co-electrolysis steam superheater 44 to the co-electrolysis steam generator 42 will be described later. In addition, water is supplied to the co-electrolysis steam generator 42 from the outside. The co-electrolysis steam generator 42 heats water with thermal energy in the medium temperature range after use in the co-electrolysis steam superheater 44 to generate steam. The heat after use in the co-electrolysis steam superheater 44 is supplied from the co-electrolysis intermediate line 46, which is in the medium temperature range lower than the heat supplied from the downstream supply line 23, and is used in the co-electrolysis steam generator 42 to efficiently utilize the heat of the high temperature gas reactor 1.

[0030] (Steam preheater for co-electrolysis) The co-electrolysis steam preheater 43 is supplied with steam from the co-electrolysis steam generator 42. The co-electrolysis steam preheater 43 is connected to the supply header section 22 by the downstream supply line 23. Secondary helium is supplied to the co-electrolysis steam preheater 43 from the supply header section 22. Thermal energy of the high temperature region of the HTGR 1 is supplied to the co-electrolysis steam preheater 43 via the secondary helium. The co-electrolysis steam preheater 43 heats steam by utilizing the thermal energy of the high temperature region contained in the secondary helium. The steam heated by the co-electrolysis steam preheater 43 contains thermal energy of the medium temperature region.

[0031] (Steam superheater for co-electrolysis) The co-electrolysis steam superheater 44 is supplied with steam from the co-electrolysis steam preheater 43. The co-electrolysis steam superheater 44 is also connected to the supply header section 22 by the downstream supply line 23. Secondary helium is supplied to the co-electrolysis steam superheater 44 from the supply header section 22. Thermal energy of the high temperature region of the HTGR 1 is supplied to the co-electrolysis steam superheater 44 via the secondary helium. The co-electrolysis steam superheater 44 further heats the steam by utilizing the thermal energy of the high temperature region contained in the secondary helium. The steam heated by the co-electrolysis steam superheater 44 contains thermal energy of the high temperature region of the HTGR 1.

[0032] The co-electrolysis steam superheater 44 is connected to the co-electrolysis steam generator 42 by a co-electrolysis intermediate line 46. After being supplied to the co-electrolysis steam superheater 44, the thermal energy of the secondary helium is reduced to the intermediate temperature region. The secondary helium is supplied from the co-electrolysis steam superheater 44 to the co-electrolysis steam generator 42 through the co-electrolysis intermediate line 46. This secondary helium supplies the co-electrolysis steam generator 42 with thermal energy in the intermediate temperature region after being used in the co-electrolysis steam superheater 44. Therefore, in the co-electrolysis steam generator 42, thermal energy in the intermediate temperature region is used to generate steam.

[0033] (SOEC for co-electrolysis) The co-electrolysis SOEC 41 is supplied with steam from the co-electrolysis steam superheater 44, and with carbon dioxide from the CO2 capture and supply facility 6. The co-electrolysis SOEC 41 also has a co-electrolysis hydrogen electrode 41a and a co-electrolysis oxygen electrode 41b. An electrolysis voltage is applied between the co-electrolysis hydrogen electrode 41a and the co-electrolysis oxygen electrode 41b, and electric energy is supplied to the co-electrolysis SOEC 41. The co-electrolysis SOEC 41 co-electrolyzes carbon dioxide and steam using thermal energy in the high temperature region of the high temperature gas reactor 1 contained in the steam to produce synthesis gas. The synthesis gas is a mixed gas of hydrogen and carbon monoxide. The co-electrolysis SOEC 41 is connected to the CO utilization facility 5 by a recovery line 71. The synthesis gas produced by the co-electrolysis SOEC 41 is supplied to the CO utilization facility 5 through the recovery line 71. In the co-electrolysis SOEC 41, oxygen is produced during synthesis gas production. The oxygen produced in the co-electrolysis SOEC 41 is discharged to the outside.

[0034] (CO utilization equipment) The CO utilization facility 5 is a facility that utilizes carbon monoxide in the mixed gas supplied from the co-electrolysis SOEC 41. The CO utilization facility 5 includes a hydrocarbon production facility 5a. In this embodiment, the CO utilization facility 5 is composed of only the hydrocarbon production facility 5a.

[0035] (Hydrocarbon production facility) The hydrocarbon production facility 5a is supplied with hydrogen produced in the hydrogen production SOEC 31 and a synthesis gas of carbon monoxide and hydrogen produced in the co-electrolysis SOEC 41 through a recovery line 71. The hydrocarbon production facility 5a produces hydrocarbons from the carbon monoxide and hydrogen produced in the hydrogen production SOEC 31 and the co-electrolysis SOEC 41. The hydrocarbon production facility 5a has a heat supply steam production facility 50 and a methanol or other synthesis unit 51. In this embodiment, the hydrocarbon production facility 5a produces methanol, ethanol, or the like using the methanol or other synthesis unit 51.

[0036] (Steam production facility for heat supply) The heat supply steam production facility 50 is supplied with thermal energy from the high temperature region of the high temperature gas reactor 1 via secondary helium flowing through a supply line 20. The heat supply steam production facility 50 uses the thermal energy of the high temperature gas reactor 1 to produce steam.

[0037] The heat supply steam production facility 50 has a heat supply steam generator 52 and a heat supply steam heater 53. The heat supply steam generator 52 is connected to the methanol synthesis apparatus 51 by a heat supply steam flow path 54. In the heat supply steam flow path 54, water vapor flows from the heat supply steam generator 52 to the methanol synthesis apparatus 51. The heat supply steam heater 53 is provided in the midstream portion of the heat supply steam flow path 54.

[0038] (Steam generator for heat supply) The heat supply steam generator 52 is connected to the hydrogen steam preheater 33 by a connection line 28. The heat supply steam generator 52 is supplied with secondary helium after use in the hydrogen steam preheater 33. In addition, water is supplied to the heat supply steam generator 52 from the outside. The heat supply steam generator 52 generates water vapor by utilizing heat in the medium temperature range after use in the hydrogen steam preheater 33. The generated water vapor makes effective use of thermal energy in the low temperature range.

[0039] (Steam heater for heat supply) The heat supply steam heater 53 is supplied with water steam from the heat supply steam generator 52. The heat supply steam heater 53 is also connected to the supply header section 22 by the downstream supply line 23. Secondary helium is supplied to the heat supply steam heater 53 from the supply header section 22. Thermal energy of the high temperature region of the high temperature gas reactor 1 is supplied to the heat supply steam heater 53 via the secondary helium. The heat supply steam heater 53 heats the water steam by utilizing the thermal energy of the high temperature region contained in the secondary helium.

[0040] (Methanol synthesis equipment) Steam is supplied to the methanol synthesis apparatus 51 from a heat supply steam heater 53. Thermal energy from the high temperature gas reactor 1 is supplied to the methanol synthesis apparatus 51 via the steam. In addition, hydrogen produced in the hydrogen production SOEC 31 and a mixed gas of carbon monoxide and hydrogen produced in the co-electrolysis SOEC 41 are supplied to the methanol synthesis apparatus 51 via a recovery line 71. The methanol synthesis apparatus 51 synthesizes methanol, ethanol, and the like from carbon monoxide and hydrogen by utilizing the thermal energy supplied via the steam.

[0041] (CO2 capture and supply equipment) The CO2 capture and supply equipment 6 separates and captures carbon dioxide contained in exhaust gas G from refineries, factories, etc., using a carbon dioxide absorbent, and supplies the captured carbon dioxide to the co-electrolysis SOEC 41. An amine absorption solution A is used as the absorbent. As shown in FIG. 2, the CO2 capture and supply equipment 6 has a cooling tower 60, an absorption tower 61, a regeneration tower 62, a reboiler 63, a regeneration heat exchanger 64, and a regeneration cooler 65.

[0042] (cooling tower) Exhaust gas G containing carbon dioxide is supplied to the cooling tower 60. The cooling tower 60 cools the exhaust gas G. The cooling tower 60 is connected to the bottom of the absorption tower 61 by an exhaust gas transfer line 66. The exhaust gas transfer line 66 supplies the exhaust gas G cooled in the cooling tower 60 to the absorption tower 61.

[0043] (Absorption tower) The absorption tower 61 sprays the amine absorbing solution A downward from the top. The amine absorbing solution A comes into contact with the flue gas G to absorb carbon dioxide in the flue gas G. The flue gas G from which carbon dioxide has been removed is cooled and then discharged as a clean gas from the top of the absorption tower 61. The bottom of the absorption tower 61 is connected to the top of the regeneration tower 62 by a first absorption liquid transfer line 67. The first absorption liquid transfer line 67 supplies the amine absorbing solution A to the top of the regeneration tower 62. A regeneration heat exchanger 64 is provided in the midstream part of the first absorption liquid transfer line 67 that connects the absorption tower 61 and the regeneration tower 62. The regeneration heat exchanger 64 will be described later.

[0044] (Regeneration Tower) The amine absorbing liquid A is sent to the regeneration tower 62. A reboiler 63 is provided at the bottom of the regeneration tower 62. The reboiler 63 is connected to the heat supply steam generator 52 by an intermediate reboiler line 69 .

[0045] (Reboiler) Secondary helium is supplied to the reboiler 63 from the heat supply steam generator 52 through a reboiler intermediate line 69. This secondary helium is secondary helium after thermal energy has been supplied to the heat supply steam generator 52, and contains thermal energy in the medium temperature range.

[0046] The reboiler 63 heats the amine absorbing solution A containing carbon dioxide by utilizing thermal energy in the medium temperature range after use in the heat supply steam generator 52. The amine absorbing solution A is heated to about 100°C or higher and 140°C or lower by the thermal energy after use in the heat supply steam generator 52, thereby decreasing the saturated solubility of carbon dioxide, and carbon dioxide is released from the amine absorbing solution A. The carbon dioxide absorption capacity is regenerated by cooling in the regeneration heat exchanger 64. The bottom of the regeneration tower 62 and the reboiler 63 are connected to the upper part of the absorption tower 61 by a second absorption liquid transfer line 68.

[0047] The regenerator 62 and the reboiler 63 transfer the amine absorbing liquid A to the upper part of the absorption tower 61 through the second absorbing liquid transfer line 68. A regenerating heat exchanger 64 and a regenerating cooler 65 are provided in the midstream part of the second absorbing liquid transfer line 68. The regenerating heat exchanger 64 is provided upstream of the regenerating cooler 65. The regenerating heat exchanger 64 is also connected to the midstream part of the first absorbing liquid transfer line 67. The regenerating heat exchanger 64 exchanges heat between the amine absorbing liquid A transferred from the absorption tower 61 to the regenerating tower 62 and the amine absorbing liquid A transferred from the regenerating tower 62 to the absorption tower 61, and cools the amine absorbing liquid A transferred from the regenerating tower 62 to the absorption tower 61. The regenerating cooler 65 further cools the amine absorbing liquid A cooled by the regenerating heat exchanger 64 and returns it to the absorption tower 61. The amine absorbing liquid A returned to the absorption tower 61 is reused for absorbing carbon dioxide.

[0048] The carbon dioxide released from the amine absorption solution A in the regenerator 62 is high-purity carbon dioxide with a purity of 99.9% or more and less than 100%. The top of the regenerator 62 is connected to the co-electrolysis steam flow path 45 downstream of the co-electrolysis steam preheater 43 and upstream of the co-electrolysis steam superheater 44 via a CO2 supply line 70. The regenerator 62 supplies carbon dioxide to the co-electrolysis SOEC 41 through the CO2 supply line 70 and the co-electrolysis steam flow path 45.

[0049] 1 again, the return line 24 has an upstream return line 25, a return header section 26, and a downstream return line 27. A plurality of upstream return lines 25 are provided. The plurality of upstream return lines 25 connect the hydrogen steam generator 32 and the return header section 26, the co-electrolysis steam generator 42 and the return header section 26, the co-electrolysis steam preheater 43 and the return header section 26, the heat supply steam heater 53 and the return header section 26, and the reboiler 63 and the return header section 26, respectively. To the return header section 26, secondary helium after thermal energy supply is returned from each of the hydrogen steam generator 32, the co-electrolysis steam generator 42, the co-electrolysis steam preheater 43, the heat supply steam heater 53, and the reboiler 63 through the plurality of upstream return lines 25.

[0050] The return header section 26 is connected to the intermediate heat exchanger 2 by a downstream return line 27. Secondary helium is returned from the return header section 26 to the intermediate heat exchanger 2 through the downstream return line 27. A fan F is provided in the downstream return line 27. The fan F compresses the secondary helium flowing through the downstream return line 27 and circulates it through the intermediate heat exchanger 2.

[0051] (heat utilization equipment) The heat utilization facility 8 includes the above-mentioned intermediate heat exchanger 2, a first heat exchange line 10, a second heat exchange line 11, a supply line 20, a return line 24, a connection line 28, a hydrogen production facility 3, a hydrogen production intermediate line 36, a hydrogen steam flow path 35, a co-electrolysis facility 4, a co-electrolysis intermediate line 46, a co-electrolysis steam flow path 45, a heat supply steam production facility 50, a heat supply steam flow path 54, a reboiler 63, and a reboiler intermediate line 69.

[0052] The heat utilization equipment 8 recovers thermal energy in the high temperature region of the high temperature gas reactor 1 via helium in the intermediate heat exchanger 2. The heat utilization equipment 8 supplies the thermal energy of the high temperature gas reactor 1 recovered in the intermediate heat exchanger 2 to the hydrogen production equipment 3, the co-electrolysis equipment 4, the CO utilization equipment 5, and the reboiler 63 through the above-mentioned lines and flow paths, etc., making the thermal energy of the high temperature gas reactor 1 available in stages from the high temperature side to the low temperature side. A part of the heat utilization facility 8 constitutes a steam heat utilization facility 80 and a regeneration heat utilization facility 81, which will be described later.

[0053] (Steam heat utilization equipment) The steam heat utilization facility 80 includes a first heat exchange line 10, an intermediate heat exchanger 2, a supply line 20, a connection line 28, a steam production facility for hydrogen 30, an intermediate line for hydrogen production 36, a steam flow path for hydrogen 35, a steam production facility for co-electrolysis 40, an intermediate line for co-electrolysis 46, a steam flow path for co-electrolysis 45, a steam production facility for heat supply 50, and a steam flow path for heat supply 54. The steam heat utilization facility 80 makes it possible to utilize the thermal energy of all temperature ranges, from the high temperature range to the intermediate temperature range and the low temperature range, supplied from the high temperature gas reactor 1, for producing steam.

[0054] (Regeneration heat utilization equipment) The regeneration heat utilization equipment 81 has a first heat exchange line 10, an intermediate heat exchanger 2, an upstream supply line 21, a supply header section 22, a downstream supply line 23 connected to a hydrogen steam preheater 33, the hydrogen steam preheater 33, a connection line 28, a heat supply steam generator 52, a reboiler intermediate line 69, and a reboiler 63. The regeneration heat utilization facility 81 supplies thermal energy in the low temperature range to the amine absorbing solution A that absorbs carbon dioxide in the CO2 recovery and supply facility 6.

[0055] (Trends in Utilizing Thermal Energy from High Temperature Gas Reactors) The flow of thermal energy utilization in the high temperature gas reactor 1 will be described below with reference to FIG. First, the thermal energy of the high temperature region of the high temperature gas reactor 1 is transferred to the primary helium supplied to the high temperature gas reactor 1. The primary helium reaches a high temperature of approximately 950°C. Next, the primary helium is supplied to the intermediate heat exchanger 2. In the intermediate heat exchanger 2, heat exchange occurs between the primary helium and the secondary helium. As a result, the thermal energy of the high temperature region of the high temperature gas reactor 1 is transferred to the secondary helium. The secondary helium reaches a high temperature of approximately 890°C.

[0056] The secondary helium is then supplied from the intermediate heat exchanger 2 to the supply header section 22. The secondary helium supplied to the supply header section 22 is distributed to the hydrogen steam production facility 30, the co-electrolysis steam production facility 40, and the heat supply steam production facility 50.

[0057] In the hydrogen steam production facility 30, secondary helium is supplied to a hydrogen steam preheater 33 and a hydrogen steam superheater 34, respectively.

[0058] Thermal energy of the high temperature range contained in the secondary helium is supplied to the hydrogen steam preheater 33. The hydrogen steam preheater 33 uses the supplied thermal energy of the high temperature range to heat the water vapor of about 150°C supplied from the steam generator. As a result, the temperature of the water vapor becomes about 600°C.

[0059] The hydrogen steam superheater 34 is supplied with thermal energy in the high temperature range contained in the secondary helium. The hydrogen steam superheater 34 uses the supplied thermal energy in the high temperature range to further heat the water steam supplied from the hydrogen steam preheater 33. As a result, the temperature of the water steam becomes approximately 800°C. The secondary helium loses a portion of its thermal energy, and the thermal energy contained in the secondary helium becomes thermal energy in the medium temperature range. The secondary helium is then supplied from the hydrogen steam superheater 34 to the hydrogen steam generator 32.

[0060] The medium temperature range thermal energy of the secondary helium after the thermal energy of the high temperature range is used is supplied to the hydrogen steam generator 32. The hydrogen steam generator 32 uses the supplied medium temperature range thermal energy to heat water supplied from the outside, generating steam at about 150°C.

[0061] In this way, thermal energy is utilized in stages, from the hydrogen steam superheater 34 on the high temperature side to the hydrogen steam generator 32 on the low temperature side. The secondary helium that has supplied thermal energy to the hydrogen steam preheater 33 is sent to the heat supply steam generator 52 through the connection line 28. In addition, the secondary helium that has supplied thermal energy to the hydrogen steam generator 32 is returned to the return header section 26.

[0062] In the co-electrolysis steam production facility 40, secondary helium is supplied to a co-electrolysis steam preheater 43 and a co-electrolysis steam superheater 44, respectively.

[0063] Thermal energy of the high temperature range contained in the secondary helium is supplied to the co-electrolysis steam preheater 43. The co-electrolysis steam preheater 43 uses the supplied thermal energy of the high temperature range to heat the approximately 150°C steam supplied from the co-electrolysis steam generator 42. As a result, the temperature of the steam becomes approximately 600°C.

[0064] The co-electrolysis steam superheater 44 is supplied with thermal energy of the high temperature region contained in the secondary helium. The co-electrolysis steam superheater 44 further heats the steam supplied from the co-electrolysis steam preheater 43 by using the supplied thermal energy of the high temperature region. As a result, the temperature of the steam becomes approximately 800°C. The secondary helium loses a portion of its thermal energy, and the thermal energy contained in the secondary helium becomes thermal energy of the medium temperature region. The secondary helium is then supplied from the co-electrolysis steam superheater 44 to the co-electrolysis steam generator 42.

[0065] Thermal energy in the intermediate temperature range of the secondary helium after the thermal energy in the high temperature range is used is supplied to the co-electrolysis steam generator 42. The co-electrolysis steam generator 42 uses the supplied thermal energy in the intermediate temperature range to heat water supplied from the outside, generating steam at about 150°C.

[0066] In this way, thermal energy is utilized in stages from the co-electrolysis steam superheater 44 on the high temperature side toward the co-electrolysis steam generator 42 on the low temperature side. The secondary helium that has supplied thermal energy to the co-electrolysis steam preheater 43 and the secondary helium that has supplied thermal energy to the co-electrolysis steam generator 42 are each returned to the return header section 26.

[0067] In the heat supply steam production facility 50, secondary helium is supplied to a heat supply steam generator 52 and a heat supply steam heater 53.

[0068] Heat supply steam generator 52 is supplied with thermal energy in the medium temperature range from hydrogen steam preheater 33 after the thermal energy of the high temperature range has been used in hydrogen steam preheater 33. Heat supply steam generator 52 uses the supplied thermal energy of the medium temperature range to heat water supplied from the outside and generate steam. As a result, the secondary helium loses a portion of its thermal energy, and the thermal energy contained in the secondary helium becomes thermal energy in the low temperature range.

[0069] Heat energy in the high temperature range contained in the secondary helium is supplied to the heat supply steam heater 53. The heat supply steam heater 53 utilizes the supplied heat energy in the high temperature range to heat the water vapor supplied from the steam generator. The secondary helium that has supplied thermal energy to the heat supply steam heater 53 is returned to the return header section 26.

[0070] The secondary helium that has supplied thermal energy to the heat supply steam generator 52 is supplied to the reboiler 63. That is, thermal energy in the low temperature range contained in the supplied secondary helium is supplied to the reboiler 63. The reboiler 63 extracts thermal energy in the low temperature range from the supplied secondary helium and supplies it to the amine absorbing solution A. As a result, the amine absorbing solution A is heated and its carbon dioxide absorbency is regenerated.

[0071] In this way, thermal energy is utilized in stages, from the high-temperature side hydrogen steam preheater 33 to the medium-temperature side heat supply steam generator 52, from the medium-temperature side heat supply steam generator 52 to the low-temperature side reboiler 63, and from the reboiler 63 to the amine absorption liquid A. The secondary helium that has supplied thermal energy to the steam generator for the reboiler 63 is returned to the return header section 26.

[0072] The secondary helium returned to the return header section 26 is pressurized by the fan F and returned to the intermediate heat exchanger 2. The secondary helium returned to the intermediate heat exchanger 2 is supplied with thermal energy of the high temperature region of the high temperature gas reactor 1 again by heat exchange with the primary helium, and is used again to supply thermal energy to each facility and device.

[0073] Incidentally, carbon dioxide is absorbed into the amine absorbing solution A in the absorption tower 61 in a temperature range of 100°C or less, and is heated to about 140°C in the regeneration tower 62 to regenerate the amine absorbing solution A. This utilizes the property that the saturated absorption amount of carbon dioxide differs depending on the temperature range of the amine absorbing solution A, that is, the amount of carbon dioxide absorbed is large in a low temperature range of 100°C or less and the amount of saturated absorption is low in a temperature range of 100°C to 140°C, and the carbon dioxide absorbed in the low temperature range is released in the high temperature range to regenerate the amine absorbing solution A. In this embodiment, thermal energy in the low temperature range is supplied to the amine absorbing solution A via secondary helium.

[0074] In this way, the recycle system 100 distributes thermal energy to the hydrogen production facility 3, the co-electrolysis facility 4, and the heat supply steam production facility 50 provided in the CO utilization facility 5 via the intermediate heat exchanger 2 that obtains thermal energy in the high temperature region from the high temperature gas reactor 1 using the heat utilization facility 8, and utilizes the thermal energy supplied from the high temperature gas reactor 1 in stages from the high temperature region toward the low temperature region. Therefore, the recycle system 100 can recycle thermal energy in stages according to the temperature zone.

[0075] (Hydrogen production using SOEC) Hereinafter, hydrogen production using the hydrogen production SOEC 31 will be described. In the hydrogen production SOEC 31, an electrolysis voltage is applied between the hydrogen production hydrogen electrode 31a and the hydrogen production oxygen electrode 31b, causing a reaction shown in formula (1) to occur in the hydrogen production hydrogen electrode 31a, and a reaction shown in formula (2) to occur in the hydrogen production oxygen electrode 31b.

[0076]

number

[0077]

number

[0078] In the entire hydrogen production SOEC 31, the endothermic reaction shown in formula (3) occurs.

[0079]

number

[0080] The electrolysis in the hydrogen production SOEC 31 utilizes the thermal energy contained in the steam in the high temperature region of the high temperature gas reactor 1. For this reason, the steam is electrolyzed at an electrolysis voltage equal to or lower than the thermal neutral point (approximately 1.29 V in the hydrogen production SOEC 31) where the exothermic reaction and the endothermic reaction are balanced.

[0081] (Hydrogen production by SOEC for co-electrolysis) Hereinafter, co-electrolysis of carbon dioxide and water vapor using the SOEC 41 for co-electrolysis will be described. In the co-electrolysis SOEC 41, an electrolysis voltage is applied between the co-electrolysis hydrogen electrode 41a and the co-electrolysis oxygen electrode 41b. As a result, the reactions shown in formulas (4) and (5) occur at the co-electrolysis hydrogen electrode 41a, and the reaction shown in formula (6) occurs at the co-electrolysis oxygen electrode.

[0082]

number

[0083]

number

[0084]

number

[0085] In the entire co-electrolysis SOEC 41, an endothermic reaction shown in formula (7) occurs.

[0086]

number

[0087] In the co-electrolysis of the SOEC for co-electrolysis, the thermal energy contained in the steam in the high temperature region of the high temperature gas reactor 1 is utilized. Therefore, carbon dioxide and steam are co-electrolyzed at an electrolysis voltage equal to or lower than the thermal neutral point (approximately 1.35 V in the SOEC 41 for co-electrolysis) where the exothermic reaction and the endothermic reaction are balanced.

[0088] (Carbon resource circulation) Next, the circulation of carbon resources by the recycle system 100 will be described with reference to FIG. First, the CO2 capture and supply equipment 6 separates and captures carbon dioxide contained in the exhaust gas G discharged from an oil refinery, a factory, etc. The captured carbon dioxide is supplied to the co-electrolysis SOEC 41 via a CO2 supply line 70 together with high-temperature steam containing thermal energy from the high-temperature gas reactor 1.

[0089] In the co-electrolysis SOEC 41, co-electrolysis of carbon dioxide and water vapor is carried out to produce a synthesis gas of carbon monoxide and hydrogen. That is, in the co-electrolysis SOEC 41, carbon dioxide is reduced to carbon monoxide. The synthesis gas is supplied to the hydrocarbon production facility 5a of the CO utilization facility 5 together with hydrogen produced in the hydrogen production SOEC 31.

[0090] The hydrocarbon production facility 5a of this embodiment produces hydrocarbon compounds such as methanol and ethanol from the synthesis gas (carbon monoxide and hydrogen) produced in the co-electrolysis SOEC 41. The produced methanol, ethanol, etc. are used as raw materials for olefins (ethylene, propylene, etc.), which are basic substances of chemical products.

[0091] In this way, the recycle system 100 separates and captures carbon dioxide contained in exhaust gas G from refineries, factories, etc., using the CO2 capture and supply facility 6, and reuses the carbon dioxide as a carbon resource. Therefore, in the recycle system 100, the captured carbon dioxide is used in a co-electrolytic SOEC to produce synthetic gas (CO+H2), which is then converted into hydrocarbon compounds such as methanol, which become raw materials for chemical products such as olefins, and ultimately become plastic resins such as polyethylene (PE) and polypropylene (PP), and carbon dioxide is fixed in the final products such as plastic resins, thereby achieving carbon neutrality.

[0092] In this embodiment, the recycling system 100 includes a high-temperature gas reactor 1 as a source of thermal energy in a high-temperature region, a co-electrolysis SOEC 41 that produces carbon monoxide and hydrogen as synthesis gas through a co-electrolysis reaction of carbon dioxide and water vapor using the thermal energy of the co-electrolysis SOEC 41, and a CO utilization facility 5 that utilizes the carbon monoxide and is provided so as to be able to supply carbon monoxide from the co-electrolysis SOEC 41.

[0093] This allows the co-electrolysis reaction, which is an endothermic reaction, to be carried out by supplying thermal energy from the high-temperature gas reactor 1. This allows operation at an electrolysis voltage below the thermal neutral point, thereby suppressing the energy loss that occurs when electrical energy is converted into Joule heat. This makes it possible to obtain carbon monoxide with less electrical energy. In addition, since carbon dioxide can be electrolyzed together with water, carbon deposition in the co-electrolysis SOEC 41 due to a local deficiency in H2O concentration can be suppressed. This makes it possible to reduce the risk of carbon deposition from carbon monoxide (coking phenomenon), causing malfunctions in the device, and the like. Furthermore, the carbon monoxide produced in the co-electrolysis SOEC 41 can be utilized. Therefore, carbon dioxide can be reused with less electrical energy and the risk of carbon deposition can be reduced.

[0094] In this embodiment, the recycle system 100 further includes a heat utilization facility 8 that enables the thermal energy supplied from the high temperature gas reactor 1 to be utilized in stages from the high temperature side to the low temperature side. The heat utilization facility 8 includes an intermediate heat exchanger 2 that supplies thermal energy of the high temperature region of the high temperature gas reactor 1, a hydrogen production facility 3 connected to the intermediate heat exchanger 2 via a plurality of lines, a co-electrolysis facility 4, and a heat supply steam production facility 50 provided in the CO utilization facility 5. The multiple lines are a supply line 20, a return line 24, a connecting line 28, an intermediate line 36 for hydrogen production, and an intermediate line 46 for co-electrolysis.

[0095] As a result, in the recycle system 100, the thermal energy supplied from the high temperature gas reactor 1 can be used in stages from the high temperature side to the low temperature side, thereby achieving so-called cascade utilization of heat. Specifically, in the hydrogen production facility 3, secondary helium is supplied from the hydrogen steam superheater 34 to the hydrogen steam generator 32 through the hydrogen production intermediate line 36, so that the thermal energy of the high-temperature gas reactor 1 can be utilized in the high-temperature side hydrogen steam superheater 34, and then the thermal energy of the high-temperature gas reactor 1 can be utilized in the low-temperature side hydrogen steam generator 32. In addition, in the co-electrolysis facility 4, secondary helium is supplied from the co-electrolysis steam superheater 44 to the co-electrolysis steam generator 42 through the co-electrolysis intermediate line 46, so that the thermal energy of the high-temperature gas reactor 1 can be utilized in the co-electrolysis steam superheater 44 on the high-temperature side, and then the thermal energy of the high-temperature gas reactor 1 can be utilized in the co-electrolysis steam generator 42 on the low-temperature side. In the regeneration heat utilization facility 81, secondary helium is supplied from the high-temperature side hydrogen steam preheater 33 to the medium-temperature side heat supply steam generator 52 through the connection line 28, and from the medium-temperature side heat supply steam generator 52 to the low-temperature side reboiler 63 through the reboiler intermediate line 69, so that the thermal energy of the high-temperature gas reactor 1 can be utilized in the high-temperature side hydrogen steam preheater 33 and the medium-temperature side heat supply steam generator 52, and then the thermal energy of the high-temperature gas reactor 1 can be utilized in the low-temperature side reboiler 63. This allows the reboiler 63 to extract thermal energy in the low-temperature region from the secondary helium and utilize it for regenerating the amine absorption solution A. In this manner, in the recycle system 100, the heat utilization facility 8 can effectively utilize thermal energy.

[0096] In this embodiment, the recycle system 100 recovers carbon dioxide from either the CO utilization facility 5 or the outside, and includes a CO 2 recovery and supply facility 6 that is provided so as to be able to supply carbon dioxide to the co-electrolysis SOEC 41.

[0097] This makes it possible to separate carbon dioxide from exhaust gas G from refineries, factories, etc., and capture the exhausted carbon dioxide. The captured carbon dioxide is reduced to carbon monoxide in the co-electrolysis SOEC 41 and utilized in the CO utilization facility 5. This makes it possible to reduce carbon dioxide emissions. This makes it possible to achieve so-called carbon neutrality, in which the net carbon dioxide emissions are zero.

[0098] In this embodiment, the heat utilization facility 8 further includes a regenerating heat utilization facility 81 that supplies thermal energy in a low temperature range to the amine absorbing solution A that absorbs carbon dioxide in the CO2 recovery and supply facility 6.

[0099] As a result, the amine absorbing solution A can be heated by utilizing the thermal energy of the high-temperature gas reactor 1. Therefore, the amine absorbing solution A releases carbon dioxide, and the carbon dioxide absorption capacity of the amine absorbing solution A is regenerated. Therefore, there is no need to separately prepare a heat source for regenerating the amine absorbing solution A, and it is possible to save thermal energy.

[0100] In this embodiment, the recycle system 100 includes a hydrogen producing SOEC 31 that produces hydrogen by electrolysis of steam using thermal energy from a high temperature gas reactor 1 .

[0101] This allows the electrolysis of water, which is an endothermic reaction, to be carried out using the thermal energy of the high-temperature gas reactor 1. This makes it possible to operate at an electrolysis voltage below the thermal neutral point. This makes it possible to obtain hydrogen with less electrical energy. Furthermore, since the hydrogen production SOEC 31 uses the thermal energy of the high-temperature region of the high-temperature gas reactor 1 for the electrolysis of water vapor, it is possible to produce hydrogen with less electrical energy. In addition, the hydrogen production SOEC 31 can electrolyze water vapor using the thermal energy of the high temperature gas reactor 1, so that no carbon dioxide is generated during hydrogen production, and so-called CO2-free hydrogen can be produced.

[0102] In this embodiment, the CO utilization facility 5 is provided so as to be capable of supplying carbon monoxide and hydrogen from the co-electrolysis SOEC 41 and so as to be capable of supplying hydrogen from the hydrogen production SOEC 31, and includes a hydrocarbon production facility 5a that produces hydrocarbon compounds from carbon monoxide and hydrogen.

[0103] This allows the carbon monoxide produced in the co-electrolysis SOEC 41 to be reduced to hydrocarbon compounds. Furthermore, only hydrogen can be supplied from the hydrogen production SOEC 31 to the CO utilization facility 5. This allows the amount of hydrogen supplied relative to carbon monoxide to be adjusted, thereby preventing a shortage of hydrogen for the reduction of carbon monoxide.

[0104] Second Embodiment (Recycling System) Hereinafter, a recycling system 200 according to a second embodiment of the present disclosure will be described with reference to FIG. In the recycle system 200 shown in Fig. 3, the CO utilization facility 205 has an iron-making facility 5b. The CO utilization facility 205 of this embodiment is composed only of the iron-making facility 5b.

[0105] (Steel manufacturing facilities) The steelmaking facility 5b has a heat supply steam production facility 50 and a steelmaking facility main body 251. The heat energy of the high temperature gas reactor is supplied to the steelmaking facility main body 251 from the heat supply steam production facility 50 via steam. The steelmaking facility main body 251 is connected to the hydrogen production SOEC 31 and the co-electrolysis SOEC 41 via a recovery line 71. The steelmaking facility main body 251 is supplied with hydrogen from the hydrogen production SOEC 31 through the recovery line 71, and is supplied with carbon monoxide and hydrogen from the co-electrolysis SOEC 41. The steelmaking facility main body 251 reduces iron ore by the DRI (Directly Reduced Iron) method using carbon monoxide and hydrogen to produce steel. Carbon dioxide is generated during steelmaking. The steelmaking facility main body 251 is connected to the cooling tower 60 of the CO2 capture and supply facility 6 via a CO2 transfer line 72. The steelmaking facility main body 251 transfers carbon dioxide to the cooling tower 60 through the CO2 transfer line 72. Carbon dioxide transferred from the steelmaking facility main body 251 is purified in the CO2 capture and supply facility 6 and then supplied to the co-electrolysis SOEC 41.

[0106] In addition, the steelmaking facility main body 251 is connected to the hydrogen production SOEC 31 and the co-electrolysis SOEC 41 by an oxygen recovery line 73. Oxygen produced in the hydrogen production SOEC 31 and the co-electrolysis SOEC 41 is supplied to the steelmaking facility main body 251 through the oxygen recovery line 73.

[0107] In this embodiment, the CO utilization facility 205 is provided so as to be capable of supplying carbon monoxide from the co-electrolysis SOEC 41 and hydrogen from the hydrogen production SOEC 31, and has an iron-making facility 5b that produces iron by reduction of iron ore using carbon monoxide and hydrogen.

[0108] In the conventional DRI system, natural gas (methane) is used as a raw material to generate carbon monoxide, which is then used to reduce iron ore. On the other hand, the recycle system 200 of the present embodiment adopts the above-mentioned configuration, and thus combines the DRI system with the co-electrolysis SOEC 41, and can reduce iron ore by the DRI method using carbon monoxide and hydrogen produced in the co-electrolysis SOEC 41 and hydrogen produced in the hydrogen production SOEC 31, instead of natural gas (methane). This allows iron to be produced without using natural gas as a raw material. In general, in steelmaking, coke (carbon) is added to iron ore, and the iron ore is reduced with the coke to produce pig iron while emitting CO2. This method of steelmaking using coke is an exothermic reaction, and the reduction reaction proceeds spontaneously by adding coke to the iron ore. However, hydrogen reduction steelmaking, in which iron ore is reduced with hydrogen, has been developed to reduce iron ore because it emits a large amount of CO2. However, hydrogen reduction steelmaking is an endothermic reaction, so there is a problem in maintaining a high temperature atmosphere. On the other hand, the DRI method is a method of reducing iron ore with CO, and like the ironmaking method using coke, the DRI method is also an exothermic reaction. However, since the DRI method emits CO2 during the reduction of iron ore, if this CO2 is captured and CO and H2 are produced as synthesis gas in a co-electrolysis SOEC41, and this synthesis gas is used for steelmaking using the DRI method, it is possible to generate heat during hydrogen reduction steelmaking and compensate for the endothermic reaction of hydrogen reduction steelmaking. In hydrogen reduction steelmaking, the reduction of iron ore (iron oxide) using hydrogen is an endothermic reaction, whereas the DRI process is an exothermic reaction that proceeds spontaneously. Therefore, by simultaneously reducing iron ore using the DRI process and producing steel, the exothermic reaction of CO reduction in the DRI process compensates for the endothermic reaction in hydrogen reduction steelmaking, and the synthesis gas produced in the co-electrolysis SOEC41 serves as a heat carrier.

[0109] In this embodiment, the steelmaking facility 5b sends carbon dioxide generated in the steelmaking process by the DRI method to the CO2 capture and supply facility 6, which then supplies the carbon dioxide to the co-electrolysis SOEC 41. This allows the co-electrolysis SOEC 41 to reuse the supplied carbon dioxide for producing carbon monoxide. The carbon monoxide produced in the co-electrolysis SOEC 41 is used again for the reduction of iron ore by the DRI method in the steelmaking facility 5b. In this way, the recycle system 200 is a CO2 closed system that does not discharge carbon monoxide to the external environment, and is a carbon-neutral system.

[0110] In this embodiment, the iron-making facility 5b is provided so as to be supplied with oxygen produced by the hydrogen production SOEC 31 and the co-electrolysis SOEC 41.

[0111] In the DRI method, it is necessary to blow high-purity oxygen into high-temperature reducing gas. However, according to this embodiment, the oxygen produced in the hydrogen production SOEC 31 and the co-electrolysis SOEC 41 can be used in the DRI steelmaking process without blowing in additional high-purity oxygen in the steelmaking process.

[0112] (Other embodiments) Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of the present disclosure are also included.

[0113] In the above embodiment, helium is used as the heat medium that enters the high-temperature gas reactor 1 and is directly supplied with the thermal energy of the high-temperature gas reactor 1, but this is not limited thereto. The heat medium that enters the high-temperature gas reactor 1 may be any heat medium that is thermochemically stable, such as helium.

[0114] In the above embodiment, carbon dioxide is separated and captured from the exhaust gas G of an oil refinery, a factory, or the like, and then directly supplied to the SOEC 41 for co-electrolysis, but the present invention is not limited to this. For example, the separated and captured carbon dioxide may be directly stored underground or underground in an abandoned oil field, etc.

[0115] In the above embodiment, the CO2 capture and supply facility 6 may capture carbon dioxide captured from the atmosphere and supply it to the co-electrolysis SOEC 41, in addition to the carbon dioxide separated and captured from the exhaust gas G of an oil refinery or factory. In this case, a direct air capture (DAC) also serves as a carbon dioxide capture and supply source. By capturing CO2 from the atmosphere, it becomes possible to achieve negative emissions, and carbon neutrality can be achieved on a wider scale.

[0116] In the above embodiment, the amine absorbing solution A is used as the carbon dioxide absorbent, but the present invention is not limited thereto. A solid absorbent such as a ceramic absorbent may be used as the carbon dioxide absorbent. In this case, the absorption tower 61 and the regeneration tower 62 are integrated into one tower, a solid absorbent is placed in the one tower, and the process of absorbing carbon dioxide and the process of regenerating the absorbent must be switched in sequence.

[0117] In the first embodiment, the hydrocarbon production facility 5a has a methanol synthesis unit 51 and produces methane, but this is not limited thereto. The hydrocarbon production facility 5a may produce methanol or ethylene, or may produce other hydrocarbons such as olefins and paraffins by FT (Fischer-Tropsch) synthesis. In this case, the produced hydrocarbon compounds such as methanol and ethanol can be used as raw materials for alternative synthetic fuels such as gasoline, diesel, and jet fuel, in addition to being used as raw materials for chemical products.

[0118] In the first embodiment, the CO utilization facility 5 is composed of only the hydrocarbon production facility 5a, and in the second embodiment, the CO utilization facility 205 is composed of only the iron-making facility 5b. However, the CO utilization facility 5, 205 may include both the hydrocarbon production facility 5a and the iron-making facility 5b.

[0119] <Additional Notes> The recycle systems 100 and 200 described in the respective embodiments can be understood, for example, as follows.

[0120] (1) The recycling system 100, 200 according to the first aspect includes a high-temperature gas reactor 1 as a source of thermal energy in a high-temperature region, a co-electrolysis SOEC 41 that produces carbon monoxide and hydrogen by co-electrolysis of carbon dioxide and water vapor using thermal energy from the co-electrolysis SOEC 41, and a CO utilization facility 5, 205 that utilizes the carbon monoxide and is provided so as to be able to supply carbon monoxide from the co-electrolysis SOEC 41.

[0121] This allows the co-electrolysis reaction, which is an endothermic reaction, to be carried out by supplying thermal energy from the high-temperature gas reactor 1. This allows operation at an electrolysis voltage below the thermal neutral point, making it possible to obtain carbon monoxide with less electrical energy. In addition, since carbon dioxide can be electrolyzed together with water, carbon deposition in the co-electrolysis SOEC 41 due to a local deficiency in H2O concentration can be suppressed. Furthermore, the carbon monoxide produced in the co-electrolysis SOEC 41 can be utilized.

[0122] (2) The recycle system 100, 200 of a second aspect is the recycle system 100, 200 of (1), further comprising a heat utilization facility 8 that enables the thermal energy supplied from the high temperature gas reactor 1 to be utilized in stages from the high temperature side to the low temperature side, and the heat utilization facility 8 may include an intermediate heat exchanger 2 that supplies thermal energy of the high temperature region of the high temperature gas reactor 1, a hydrogen production facility 3 connected to the intermediate heat exchanger 2 via a plurality of lines, a co-electrolysis facility 4, and a heat supply steam production facility 50 provided in the CO utilization facility 5. Examples of the lines include a supply line 20, a return line 24, a connecting line 28, an intermediate line 36 for hydrogen production, and an intermediate line 46 for co-electrolysis.

[0123] As a result, in the recycle systems 100 and 200, the thermal energy supplied from the high temperature gas reactor 1 can be used in stages from the high temperature side to the low temperature side, thereby achieving so-called cascade utilization of heat.

[0124] (3) The recycle system 100, 200 of a third aspect may be the recycle system 100, 200 of (2), further including a CO2 recovery and supply facility 6 that recovers carbon dioxide from either the CO utilization facility 5, 205 or an outside facility and is capable of supplying carbon dioxide to the co-electrolysis SOEC 41.

[0125] This allows the exhausted carbon dioxide to be captured. The captured carbon dioxide is reduced to carbon monoxide in the co-electrolysis SOEC 41 and used in the CO utilization facility 5,205. This allows the amount of carbon dioxide emissions to be reduced. Carbon dioxide can also be captured from the atmosphere.

[0126] (4) The recycling system 100, 200 of the fourth aspect is the recycling system 100, 200 of (3), wherein the heat utilization equipment may further include a regenerative heat utilization equipment 81 that supplies low-temperature thermal energy to an absorbent that absorbs carbon dioxide in the CO2 recovery and supply equipment 6. An example of the absorbent is amine absorbing solution A.

[0127] This makes it possible to heat the absorbent by utilizing the thermal energy of the high temperature gas reactor 1. Therefore, the absorbent releases carbon dioxide, and the carbon dioxide absorption capacity of the absorbent is regenerated.

[0128] (5) The fifth aspect of the recycle system 100, 200 may be any of the recycle systems 100, 200 of (1) to (4) and may include a hydrogen production SOEC 31 that produces hydrogen by electrolysis of steam using thermal energy of the high-temperature gas reactor 1.

[0129] This allows the electrolysis of water, which is an endothermic reaction, to be carried out by utilizing the thermal energy of the high temperature gas reactor 1. This makes it possible to operate the reactor at an electrolysis voltage equal to or lower than the thermal neutral point.

[0130] (6) The recycling system 100, 200 of a sixth aspect is the recycling system 100, 200 of (5), wherein the CO utilization facility 5, 205 is provided so as to be capable of supplying carbon monoxide and hydrogen from the co-electrolysis SOEC 41 and so as to be capable of supplying hydrogen from the hydrogen production SOEC 31, and may include a hydrocarbon production facility 5a that produces hydrocarbon compounds from carbon monoxide and hydrogen.

[0131] This makes it possible to reduce the carbon monoxide produced in the co-electrolysis SOEC 41 to hydrocarbons. Furthermore, only hydrogen can be supplied from the hydrogen production SOEC 31 to the CO utilization facility 5,205.

[0132] (7) The seventh aspect of the recycling system 100, 200 is the recycling system 100, 200 of (5) or (6), wherein the CO utilization facility 5, 205 is provided so as to be capable of supplying carbon monoxide from the co-electrolysis SOEC 41 and capable of supplying hydrogen from the hydrogen production SOEC 31, and includes an iron-making facility 5b that produces iron by reduction of iron ore using carbon monoxide and hydrogen, and the iron-making facility 5b may be provided so as to be supplied with oxygen produced by the co-electrolysis SOEC 41 and the hydrogen production SOEC 31.

[0133] As a result, iron ore can be reduced to produce steel using carbon monoxide produced in the co-electrolysis SOEC 41 and hydrogen produced in the hydrogen production SOEC 31. Furthermore, in the steelmaking process, oxygen produced in the co-electrolysis SOEC 41 and the hydrogen production SOEC 31 can be used without separately blowing in high-purity oxygen. [Explanation of symbols]

[0134] 1...High-temperature gas-cooled reactor 2...Intermediate heat exchanger 3...Hydrogen production equipment 4...Co-electrolysis equipment 5...CO utilization equipment 5a...Hydrocarbon production equipment 5b...Iron-making equipment 6...CO2 capture and supply equipment 8...Heat utilization equipment 10...First heat exchange line 11...Second heat exchange line 20...Supply line 21...Upstream supply line 22...Supply header section 23...Downstream supply line 24...Return line 25...Upstream return line 26...Return header section 27...Downstream return line 28...Connection line 30...Steam production equipment for hydrogen 31...SOEC for hydrogen production 31a...Hydrogen electrode for hydrogen production 31b...Oxygen electrode for hydrogen production 32...Steam generator for hydrogen 33...Steam preheater for hydrogen 34...Steam superheater for hydrogen 35...Steam flow path for hydrogen 36...Intermediate line for hydrogen production 40...Steam production equipment for co-electrolysis 41...SOEC for co-electrolysis 41a...Hydrogen electrode for co-electrolysis 41b...Oxygen electrode for co-electrolysis 42...Steam generator for co-electrolysis 43...Steam preheater for co-electrolysis 44...Steam superheater for co-electrolysis 45...Steam flow path for co-electrolysis 46...Intermediate line for co-electrolysis 50...Steam production equipment for heat supply 51...Methanol synthesis equipment 52...Steam generator for heat supply 53...Steam heater for heat supply 54...Steam flow path for heat supply 60...Cooling tower 61...Absorption tower 62...Regeneration tower 63...Reboiler 64...Heat exchanger for regeneration 65...Cooler for regeneration 66...Exhaust gas transfer line 67...First absorption liquid transfer line 68...Second absorption liquid transfer line 69...Intermediate line for reboiler 70...CO2 supply line 71...Recovery line 72...CO2 transfer line 73...Oxygen recovery line 80...Heat utilization equipment for steam 81...Heat utilization equipment for regeneration 100...Recycle system 200...Recycle system 205...CO utilization equipment 251...Iron-making equipment A...Amine absorbent (absorbent material) F...Fan G...Exhaust gas

Claims

1. A high-temperature gas reactor as a supply source of high-temperature thermal energy, which is thermal energy contained in water vapor at 700°C or more and 1000°C or less; a heat utilization facility having a co-electrolysis facility including a co-electrolysis SOEC that enables the thermal energy supplied from the high-temperature gas reactor to be utilized in stages from the high-temperature side to the low-temperature side and produces carbon monoxide and hydrogen by co-electrolysis of carbon dioxide and water vapor using the thermal energy of the high-temperature gas reactor; a CO utilization facility that utilizes carbon monoxide and is provided so as to be capable of supplying carbon monoxide from the co-electrolysis SOEC; Equipped with The heat utilization facility includes: an intermediate heat exchanger for supplying thermal energy to the high temperature region of the high temperature gas reactor; A hydrogen production facility connected to the intermediate heat exchanger via a plurality of lines; a heat supply steam production facility provided in the CO utilization facility; A recycling system further comprising:

2. 2. The recycling system according to claim 1, further comprising a CO2 recovery and supply facility that recovers carbon dioxide from either the CO utilization facility or an outside source and is capable of supplying carbon dioxide to the co-electrolysis SOEC.

3. The heat utilization facility includes: The recycling system according to claim 2, further comprising a heat utilization facility for regeneration that supplies low-temperature thermal energy, which is thermal energy contained in water vapor at 100°C or higher and 300°C or lower, to an absorbent that absorbs carbon dioxide in the CO2 recovery and supply facility.

4. A recycling system described in any one of claims 1 to 3, wherein the hydrogen production equipment is equipped with a hydrogen production SOEC that produces hydrogen by electrolysis of water vapor using thermal energy from the high-temperature gas reactor.

5. The recycling system according to claim 4, wherein the CO utilization facility has a hydrocarbon production facility capable of supplying carbon monoxide and hydrogen from the co-electrolysis SOEC and capable of supplying hydrogen from the hydrogen production SOEC, and which produces hydrocarbon compounds from carbon monoxide and hydrogen.

6. The CO utilization facility is provided so as to be capable of supplying carbon monoxide from the co-electrolysis SOEC and hydrogen from the hydrogen production SOEC, and has an ironmaking facility that produces iron by reducing iron ore using carbon monoxide and hydrogen, The recycling system according to claim 4 or 5, wherein the iron-making facility is provided so as to be supplied with oxygen produced by the co-electrolysis SOEC and the hydrogen production SOEC.

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