JP-2026076109-A - Thermal energy generation system and thermal energy generation method

Abstract

[Problem] To provide a thermal energy generation system and thermal energy generation method that can reduce the difficulty of separating carbon dioxide and impurities in the exhaust gas after the combustion reaction, while making use of existing combustion equipment as much as possible. [Solution] The thermal energy generation system 10 includes a water electrolysis device 20, a methanation device 30 that generates methane and water by reacting carbon dioxide with hydrogen produced in the water electrolysis device 20, a combustion device 40 that burns the methane discharged from the methanation device 30 using a combustion gas containing oxygen discharged from the water electrolysis device 20, and a CO2 distribution unit 55 that distributes and supplies the carbon dioxide discharged from the combustion device 40 to the methanation device 30 and the combustion device 40, respectively. The methanation device 30 carries out the methanation reaction using carbon dioxide from the CO2 distribution unit 55. The combustion device 40 carries out the combustion reaction by incorporating carbon dioxide from the CO2 distribution unit 55 into the combustion gas. [Selection Diagram] Figure 1

Inventors

• 國領 也恵子
• 藤澤 彰利
• 松岡 亮
• 笠原 奨平

Assignees

• 株式会社神戸製鋼所

Dates

Publication Date

20260511

Application Date

20250806

Priority Date

20241023

Claims (8)

1. A water electrolysis device that generates and discharges hydrogen and oxygen by electrolyzing water, A methanation device that produces and discharges methane and water through a methanation reaction between carbon dioxide and hydrogen produced in the water electrolysis device, A combustion device that generates thermal energy by carrying out a combustion reaction between methane discharged from the methanation device and a combustion gas containing oxygen discharged from the water electrolysis device, and discharges carbon dioxide as a reaction product of the combustion reaction, The system includes a CO2 distribution unit that distributes and supplies carbon dioxide emitted from the combustion device to the methanation device and the combustion device, respectively. The methanation apparatus is configured to carry out the methanation reaction using carbon dioxide supplied from the CO2 distribution unit. The combustion apparatus is a thermal energy generation system configured to incorporate carbon dioxide supplied from the CO2 distribution unit into the combustion gas to carry out the combustion reaction.
2. In the thermal energy generation system according to claim 1, A thermal energy generation system further comprising a first flow rate adjustment unit that adjusts the flow rate of carbon dioxide supplied to the combustion device so that the concentration of oxygen in the combustion gas is equivalent to the concentration of oxygen in the atmosphere.
3. In the thermal energy generation system according to claim 1 or 2, A thermal energy generation system further comprising a second flow rate adjustment unit that adjusts the flow rate of methane and the flow rate of oxygen supplied to the combustion device so that the combustion reaction of methane in the combustion device is carried out in an oxygen-rich state where there is more oxygen than the theoretical air ratio.
4. In the thermal energy generation system according to claim 3, The combustion apparatus is configured to discharge combustion exhaust gas containing carbon dioxide and oxygen by performing the combustion reaction in the oxygen-rich state. A thermal energy generation system comprising a CO2 distribution unit having a separator that separates high-purity CO2 gas having a predetermined carbon dioxide concentration from combustion exhaust gas discharged from the combustion device, and supplying the high-purity CO2 gas separated by the separator to the methanation device, and supplying the low-purity CO2 gas containing carbon dioxide and oxygen, and with a carbon dioxide concentration lower than the predetermined concentration, which remains after the high-purity CO2 gas has been separated from the combustion exhaust gas, to the combustion device.
5. In the thermal energy generation system according to claim 4, The CO2 distribution unit further includes a combustion exhaust gas distribution unit that supplies a portion of the combustion exhaust gas discharged from the combustion device to the separator and supplies the remaining combustion exhaust gas to the combustion device. The separator is configured to separate high-purity CO2 gas from the combustion exhaust gas supplied from the combustion exhaust gas distribution unit, and is part of a thermal energy generation system.
6. In the thermal energy generation system according to claim 1 or 2, A thermal energy generation system further comprising a third flow rate adjustment unit that adjusts the flow rate of methane supplied to the combustion device and the flow rate of oxygen supplied to the combustion device so that the combustion reaction of methane in the combustion device is carried out at a stoichiometric air ratio.
7. In the thermal energy generation system according to claim 1, A thermal energy generation system further comprising a fourth flow rate adjustment unit that adjusts the flow rate of hydrogen and the flow rate of carbon dioxide supplied to the methanation apparatus so that the ratio of hydrogen to carbon dioxide used in the methanation reaction in the methanation apparatus becomes a predetermined ratio in which hydrogen is more abundant than the stoichiometric ratio.
8. A method for generating thermal energy, A water electrolysis process that generates hydrogen and oxygen by electrolyzing water, A methanation step that produces methane and water through a methanation reaction between carbon dioxide and hydrogen produced in the water electrolysis step, A combustion step is performed in which a combustion reaction of methane produced in the methanation step is carried out using a combustion gas containing oxygen produced in the water electrolysis step, thereby generating thermal energy and emitting carbon dioxide as a reaction product of the combustion reaction. The system includes a distribution step that separates the carbon dioxide generated in the combustion step into carbon dioxide for the methanation step and carbon dioxide for the combustion step. In the methanation step, the methanation reaction is carried out using carbon dioxide for the methanation step. A method for generating thermal energy, wherein the combustion step involves adding carbon dioxide for the combustion step to the combustion gas and carrying out the combustion reaction.

Description

This invention relates to a thermal energy generation system and a thermal energy generation method. Conventionally, in order to reduce the carbon dioxide emitted during the combustion of fossil fuels, a thermal energy generation system is known that recovers the carbon dioxide generated during combustion, converts it to methane by reacting it with hydrogen, and then uses the converted methane as fuel for combustion. For example, Patent Document 1 discloses an example in which the aforementioned thermal energy generation system is used as a power generation system. This power generation system includes a generator that generates thermal energy through a combustion reaction and converts it into electricity, a dehydrogenation reactor that produces hydrogen from hydrolyzed aromatics through a dehydrogenation reaction, a separator that separates carbon dioxide from the exhaust gas generated by the combustion reaction, and a methanation device that produces methane and water by reacting the carbon dioxide separated in the separator with the hydrogen produced in the dehydrogenation reactor. The generator generates thermal energy by burning the methane produced in the methanation device together with fossil fuels. Patent Document 1 describes using atmospheric air for fuel combustion in a generator. However, as shown in Patent Document 2, for example, there are also cases where the combustion reaction is carried out by pure oxygen combustion using oxygen generated by the electrolysis of water. Patent No. 6126952Japanese Patent Publication No. 2023-181869 Figure 1 is a schematic diagram showing the general configuration of the thermal energy generation system of this embodiment.Figure 2 is a schematic diagram showing the flow rates of each working fluid in Example 1-1.Figure 3 is a diagram corresponding to Figure 2, showing Example 1-2.Figure 4 is a diagram corresponding to Figure 1, showing Embodiment 2.Figure 5 is a schematic diagram showing the flow rates of each working fluid in Example 2-1.Figure 6 is a diagram corresponding to Figure 5, showing Example 2-2.Figure 7 is a diagram corresponding to Figure 1, showing Embodiment 3.Figure 8 is a schematic diagram showing the flow rates of each working fluid in Example 3-1.Figure 9 is a diagram corresponding to Figure 8, showing Example 3-2. The embodiments and examples of the present invention will be described in detail below with reference to the drawings. (Embodiment 1) Figure 1 is a schematic diagram showing the general configuration of the thermal energy generation system 10 of this embodiment. This thermal energy generation system 10 converts carbon dioxide emitted by a combustion reaction into methane, and generates thermal energy by using the methane as fuel to carry out the combustion reaction. The thermal energy generated by the thermal energy generation system 10 can be used, for example, for power generation, metal melting and processing, glass manufacturing, or ceramic firing. Specifically, the thermal energy generation system 10 includes a water electrolyzer 20, a methanation device 30, a combustion device 40, and a high-purity CO2 separator 50. The water electrolysis device 20 is a device that decomposes water supplied from an external source into hydrogen and oxygen using electrical energy. The reaction equation for the water electrolysis reaction in the water electrolysis device 20 is as shown in equation (1) below. H 2 O → H 2 + (1/2) O 2 ……………(1) The oxygen generated by this water electrolysis reaction is supplied to the combustion device 40 via the flow path 61 and the combustion gas supply flow path 62. Meanwhile, the hydrogen generated by the water electrolysis reaction is supplied to the methanation device 30 via the flow path 63. The methanation device 30 reacts hydrogen supplied from the water electrolysis device 20 with carbon dioxide (high-purity CO2 gas) supplied from the high-purity CO2 separator 50 to produce methane and water (more precisely, water vapor). The reaction equation for this reaction (hereinafter referred to as the methanation reaction) is shown in equation (2) below. CO 2 +4H 2 →CH 4 +2H 2 O………(2) The mixture of methane and water produced by the methanation device 30 is supplied to the water separator 11 via the flow path 64. The water separator 11 is a so-called condenser, which separates the water supplied from the methanation device 30 by liquefying it through condensation. The methane, from which the water has been separated, is supplied to the combustion device 40 via the flow path 65. More specifically, the methane from which the water has been separated in the water separator 11 is supplied to the CH4 tank 31 via the flow path 65a for temporary storage, and then supplied to the combustion device 40 via the flow path 65b. The combustion device 40 is a device that burns methane supplied from the methanation device 30 via the water separator 11. Specifically, the combustion device 40 supplies the methane fuel and combus