Thermal power generation method

Abstract

To provide a thermal power generation method that can decrease the amount of carbon dioxide discharged therefrom, without requiring forcible injection of carbon dioxide present in exhaust of a thermal power station into the ground.SOLUTION: The thermal power generation method utilizing the combustion of an organic fuel and an inorganic fuel according to the present invention, with the inorganic fuel being an inorganic matter that can be combusted using oxidized carbon gas as combustion supporting gas, a hydrogenated inorganic matter with at least a portion thereof being hydrogenated, or a mixture of an inorganic matter and a hydrogenated inorganic matter, is characterized in that the inorganic fuel is combusted using oxidized carbon gas present in exhaust gas generated by the combustion of the organic fuel, as combustion supporting gas, and the carbon present in the oxidized carbon gas is solidified.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thermal power generation method. [Background technology]

[0002] 2. Description of the Related Art Thermal power generation systems equipped with power generation boilers are generally known (see, for example, Non-Patent Document 1). However, the thermal power generation system using so-called fossil fuels has a problem in that it emits carbon dioxide, which is believed to be a cause of global warming.

[0003] Therefore, efforts are being made to reduce the release of carbon dioxide into the atmosphere even in thermal power generation systems that use fossil fuels.

[0004] For example, Non-Patent Document 2 introduces the CCS efforts being undertaken in Tomakomai City, Hokkaido, and specifically explains that carbon dioxide is separated and captured from exhaust gases from thermal power plants, and that the captured carbon dioxide is injected deep underground beneath the seabed, approximately 3 to 4 km from the coast, and stored there.

[0005] It is believed that the carbon dioxide injected deep underground in this way will be stored stably for a long period of time and will dissolve into salt water over a long period of time and become minerals in the gaps between rocks.

[0006] However, there are many constraints to this type of storage, including the need for the stratum to have gaps large enough to store carbon dioxide, and for it to be covered by a stratum that is impermeable to carbon dioxide. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] “Promoting regional environmental conservation: The structure of coal-fired power plants and various environmental conservation measures”, [online], Okinawa Electric Power Co., Inc., [Retrieved June 30, 2022], Internet<URL:https: / / www.okiden.co.jp / environment / report2017 / sec6 / sec63.html> [Non-Patent Document 2] “CCS: capturing and burying CO2: After demonstration tests, it is finally nearing realization (Part 1)”, [online], November 27, 2020, Agency for Natural Resources and Energy, Ministry of Economy, Trade and Industry, [Retrieved June 16, 2022], Internet<URL:https: / / www.enecho.meti.go.jp / about / special / johoteikyo / ccs_tomakomai.html> Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above circumstances, and has an object to provide a thermal power generation method that reduces carbon dioxide emissions and does not require the treatment of injecting carbon dioxide in the exhaust gas from a thermal power plant underground. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention is realized by the following configuration. (1) A thermal power generation method of the present invention is a thermal power generation method that utilizes the combustion of an organic fuel and the combustion of an inorganic fuel, wherein the inorganic fuel is an inorganic material that can be combusted using carbon oxide gas as a combustion supporting gas, a hydrogenated inorganic material in which at least a portion of the inorganic material is hydrogenated, or a mixture of the inorganic material and the hydrogenated inorganic material, and the inorganic fuel is combusted using carbon oxide gas in exhaust gas generated by the combustion of the organic fuel as a combustion supporting gas, and carbon in the carbon oxide gas is solidified.

[0010] (2) In the above configuration (1), the inorganic substance is lithium, magnesium, aluminum, or a mixture containing two or more of lithium, magnesium, and aluminum.

[0011] (3) In the above configuration (2), the inorganic substance is magnesium.

[0012] (4) In the configuration of (3) above, the organic fuel is a fossil fuel other than liquefied natural gas, the carbon oxide gas used as the combustion supporting gas for burning the inorganic fuel is carbon dioxide gas, and the carbon dioxide gas is carbon dioxide gas recovered from the exhaust gas after passing through a denitration device, a dust collection device, and a desulfurization device through a carbon dioxide gas separation and recovery device.

[0013] (5) In the configuration of (3) above, the organic fuel is liquefied natural gas, the carbon dioxide gas used as the combustion supporting gas for burning the inorganic fuel is carbon dioxide gas, and the carbon dioxide gas is carbon dioxide gas recovered from the exhaust gas through a carbon dioxide gas separation and recovery device.

[0014] (6) In the configuration of (3) above, the solidified carbon is recovered as combustion ash together with oxides of the inorganic fuel generated by combustion of the inorganic fuel, and the solidified carbon is separated from the combustion ash, and the solidified carbon is used as a raw material for a carbon material.

[0015] (7) In the above configuration (6), the inorganic fuel is produced again using the oxide as a material and used for thermal power generation. Effect of the Invention

[0016] According to the present invention, it is possible to provide a thermal power generation method that does not require injection of carbon dioxide in exhaust gas from a thermal power plant underground and reduces the amount of carbon dioxide emissions. [Brief description of the drawings]

[0017] [Figure 1]FIG. 1 is a diagram for explaining a thermal power plant in which a thermal power generation method according to a first embodiment of the present invention is implemented. [Diagram 2] FIG. 2 is a diagram for explaining a thermal power plant in which a thermal power generation method according to a second embodiment of the present invention is implemented. [Diagram 3] FIG. 11 is a diagram for explaining a thermal power plant in which a thermal power generation method according to a fourth embodiment of the present invention is implemented. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter, referred to as embodiments) will be described in detail with reference to the accompanying drawings. In addition, the same elements are denoted by the same reference numerals throughout the description of the embodiments.

[0019] (First embodiment) The thermal power generation method of the first embodiment according to the present invention is carried out in a thermal power plant. However, since many of the components are similar to those of current thermal power plants, a description of the similarities may be omitted.

[0020] FIG. 1 is a diagram for explaining a thermal power plant in which the thermal power generation method of the present embodiment is carried out. The thermal power plant includes a generator 1, a power generation boiler 2 that drives the generator 1, an organic fuel storage tank 3 that stores organic fuel to be supplied to the power generation boiler 2, and an inorganic fuel storage tank 4 that stores inorganic fuel to be supplied to the power generation boiler 2.

[0021] The power generating boiler 2 comprises a combustion chamber 21, a steam turbine 22 whose rotating shaft is connected to the generator 1 and which is driven by steam produced in the combustion chamber 21, and piping 23 for supplying the steam to the steam turbine 22 and for supplying water that has been returned to a liquid state in a condenser (not shown) back to the combustion chamber 21.

[0022] The combustion chamber 21 includes a first combustion chamber A which receives organic fuel from the organic fuel storage tank 3 and burns the organic fuel, and a second combustion chamber B which receives inorganic fuel from the inorganic fuel storage tank 4 and burns the inorganic fuel.

[0023] The power generation boiler 2 of this embodiment is a commonly known stoker type boiler, and differs mainly in that its combustion chamber 21 is partitioned by a wall as shown by the dotted line, separating it into a first combustion chamber A and a second combustion chamber B.

[0024] The fuel supply mechanism for supplying fuel to the first combustion chamber A and the second combustion chamber B may be similar to that provided in a stoker-type boiler, and although not shown in the figure, in this embodiment, such a fuel supply mechanism is provided in the first combustion chamber A and the second combustion chamber B, respectively.

[0025] That is, a fuel supply mechanism for supplying organic fuel from the organic fuel storage tank 3 to the first combustion chamber A, and a fuel supply mechanism for supplying inorganic fuel from the inorganic fuel storage tank 4 to the second combustion chamber B are provided.

[0026] The piping 23 passes through the first combustion chamber A and the second combustion chamber B, and the heat of combustion of the organic fuel in the first combustion chamber A and the heat of combustion of the inorganic fuel in the second combustion chamber B are used to generate steam that drives the steam turbine 22.

[0027] Air is supplied to the first combustion chamber A, and the oxygen in the air and the organic fuel are combusted. For example, coal can be suitably used as the organic fuel, and carbon dioxide gas (CO2) is generated as a carbon oxide gas by combustion. In addition, since the air also contains nitrogen gas, nitrogen oxides (NOx) are also produced, and if the organic fuel is coal, it also contains sulfur components, so sulfur dioxide gas is also produced.

[0028] The exhaust gas containing carbon dioxide gas, nitrogen oxides (NOx), sulfur dioxide gas, etc. is sent from the first combustion chamber A through an exhaust pipe (not shown) as indicated by the solid arrow, to a denitrification device 5 where the nitrogen oxides (NOx) are rendered harmless. The denitration device 5 may be the same as that generally used in coal-fired power plants.

[0029] Then, the exhaust gas that has passed through the denitration device 5 is sent to the dust collector 6 through an exhaust pipe (not shown) as indicated by the solid arrow, where soot and the like contained in the exhaust gas is removed. The dust collector 6 may be the same as that generally used in coal-fired power plants.

[0030] Furthermore, the exhaust gas that has passed through the dust collector 6 is sent to a desulfurizer 7 through an exhaust pipe (not shown), as indicated by a solid arrow, where sulfur dioxide gas contained in the exhaust gas is removed. The desulfurization device 7 may be the same as that generally used in coal-fired power plants.

[0031] Then, the exhaust gas that has passed through the desulfurization device 7 is sent through an exhaust pipe (not shown) to a separation and capture device 8 that separates and captures carbon dioxide gas, as indicated by the solid arrow, and the carbon dioxide gas contained in the exhaust gas is captured.

[0032] The carbon dioxide gas thus recovered by the separation and recovery device 8 is supplied to a storage tank 81 that stores carbon dioxide gas through a gas pipe (not shown), as indicated by the dotted arrow. A booster (not shown) is provided at the inlet of the storage tank 81 so that carbon dioxide gas is supplied to the storage tank 81 in a pressurized state, and some of the carbon dioxide gas is stored in a liquefied state inside the storage tank 81.

[0033] On the other hand, the exhaust gas from which carbon dioxide gas has been removed in the separation and recovery device 8 is sent to an exhaust fan 9 through an exhaust pipe (not shown) as indicated by the solid arrow, and is then released into the atmosphere. Incidentally, this exhaust fan 9 also has a configuration that is generally provided in coal-fired power plants, and may be similar to that.

[0034] The storage tank 81 is connected to the second combustion chamber B through a gas piping (not shown), as indicated by the dotted arrow, so that the carbon dioxide gas stored in the storage tank 81 can be supplied to the second combustion chamber B.

[0035] Specifically, carbon dioxide gas is supplied from the storage tank 81 so that the pressure in the second combustion chamber B becomes slightly positive according to the output of a pressure gauge (not shown) connected to the second combustion chamber B. In order to control the pressure, a flow control valve for controlling the flow rate of the carbon dioxide gas is provided in the gas piping (not shown) from the storage tank 81 to the second combustion chamber B.

[0036] The second combustion chamber B is supplied with inorganic fuel that can be burned using carbon oxide gas, specifically carbon dioxide gas, as a combustion supporting gas from the inorganic fuel storage tank 4, and combustion takes place using the supplied carbon dioxide gas as the combustion supporting gas.

[0037] Specifically, the inorganic fuel is an inorganic substance that can be burned using carbon oxide gas such as carbon dioxide gas (CO2) or carbon monoxide gas (CO) as a combustion supporting gas, a hydrogenated inorganic substance in which at least a portion of the inorganic substance is hydrogenated, or a mixture of an inorganic substance and a hydrogenated inorganic substance, and the inorganic substance is lithium (Li), magnesium (Mg), aluminum (Al), or a mixture containing two or more of lithium, magnesium, and aluminum.

[0038] In addition, when non-hydrogenated inorganic materials are used as inorganic fuels, they become flammable when in fine powder form and must be handled as hazardous materials.

[0039] For this reason, when using a non-hydrogenated inorganic material as the inorganic fuel, it is desirable to make the inorganic material have a particle size that does not fall under the category of hazardous materials.

[0040] For example, in the case of magnesium, if the particle size is 400 μm or more, it will not be classified as a hazardous material.

[0041] On the other hand, as an inorganic matter used for the inorganic fuel, magnesium is preferable from the viewpoint of good combustibility in the second combustion chamber B. When the inorganic fuel is magnesium, the combustion reaction shown in the following formula (1) occurs. 2Mg + CO2→ 2MgO + C + heat (1)

[0042] In the combustion reaction shown in equation (1), when solid magnesium (Mg) and carbon dioxide gas (CO2) undergo a combustion reaction, the inorganic fuel magnesium oxide, i.e., magnesium oxide (MgO), and solid carbon (C) are produced. As the gas components disappear, a pressure reduction reaction occurs and the gas concentration becomes thinner. If the second combustion chamber B contains moisture, a small amount of magnesium hydroxide may be formed in addition to the magnesium oxide, which is an inorganic fuel.

[0043] If the gas concentration becomes low like this and there is a shortage of combustion supporting gas, the combustion reaction cannot be sustained, so as explained above, carbon dioxide gas is supplied to the second combustion chamber B while measuring the pressure to maintain a positive pressure.

[0044] As described above, the combustion reaction in the second combustion chamber B is a reduced pressure reaction, and a positive pressure environment is maintained by supplying carbon dioxide gas in excess of the amount of carbon dioxide gas required for the reaction. Therefore, it is preferable that the inner diameter of the exhaust pipe (not shown) that exhausts the exhaust gas from the second combustion chamber B be relatively small.

[0045] For example, by restricting the inner diameter to about 100 to 300 mmφ, it becomes easier to control the positive pressure inside the second combustion chamber B.

[0046] However, since the specific inner diameter of the exhaust pipe (not shown) needs to be matched to the internal volume of the second combustion chamber B, an inner diameter of 100 to 300 mmφ is not necessarily optimal.

[0047] For example, in clean rooms, etc., a positive pressure of 5 Pa or more is maintained to prevent outside air from entering the room. If the pressure is similarly maintained at a positive pressure of 5 Pa or more, it is possible to prevent exhaust gas from flowing back into the second combustion chamber B through the exhaust pipe (not shown), so it is good to maintain the pressure at 5 Pa or more, which is more positive than atmospheric pressure.

[0048] The second combustion chamber B is provided with an exhaust pipe (not shown) connected to an exhaust pipe (not shown) that runs from the first combustion chamber A to the denitrification device 5, as shown by the solid arrow, so that exhaust is taken in order to prevent the internal pressure from becoming too high.

[0049] However, even if there is a slight negative pressure, it does not lead to a situation where there is a shortage of combustion supporting gas, so, for example, the exhaust pressure immediately after leaving the first combustion chamber A (the exhaust pipe (not shown) near the first combustion chamber A before it joins with the exhaust pipe (not shown) from the second combustion chamber B) can be measured, and the pressure in the second combustion chamber B can be kept slightly higher than the measured pressure (for example, a pressure higher by 5 Pa or more). Even in this way, the pressure is controlled to be higher than that of the main exhaust, so that backflow of exhaust into the second combustion chamber B can be suppressed.

[0050] The carbon dioxide gas thus discharged from the second combustion chamber B reaches the separation and recovery device 8 in the flow described above, and is stored in the storage tank 81 again.

[0051] As can be seen from the above explanation, the thermal power generation method of this embodiment is a thermal power generation method that utilizes the combustion of organic fuel and the combustion of inorganic fuel, in which inorganic fuel is burned using carbon oxide gases such as carbon dioxide gas in the exhaust gas generated by the combustion of the organic fuel as a combustion supporting gas, and as a result of this combustion reaction, the carbon in the carbon oxide gas is solidified, thereby suppressing the emission of carbon oxide gases such as carbon dioxide gas, which have an impact on global warming.

[0052] On the other hand, not only in stoker-type boilers, but in all combustion chambers, combustion ash and the like accumulates, so a recovery mechanism is provided to recover the combustion ash. Although not shown in the figure, in this embodiment, a combustion ash recovery mechanism of a similar configuration is provided in each of the first combustion chamber A and the second combustion chamber B, and the combustion ash recovered from the first combustion chamber A is stored in the first combustion ash storage section, and the combustion ash recovered from the second combustion chamber B is stored in the second combustion ash storage section.

[0053] Incidentally, the soot and the like collected by the dust collector 6 may be sent to a first combustion ash storage section in which the combustion ash collected from the first combustion chamber A is stored.

[0054] The combustion ash stored in the first combustion ash storage area is almost the same as the combustion ash produced by conventional coal-fired power plants, so it can be used as an admixture for concrete, etc.

[0055] On the other hand, the combustion ash stored in the second combustion ash storage section, i.e., the combustion ash from which solidified carbon has been recovered together with the oxides of inorganic fuel, in this embodiment, consists of magnesium oxide and carbon and contains almost no other impurities.

[0056] Therefore, the carbon obtained by separating the solidified carbon from the combustion ash can be used as a raw material for carbon materials that require high purity.

[0057] Specifically, when combustion ash consisting of magnesium oxide and carbon is placed in an aqueous solution of hydrochloric acid, the magnesium oxide reacts with the hydrochloric acid to become magnesium chloride, which dissolves in the solution; on the other hand, carbon does not react with hydrochloric acid, so it does not dissolve in the solution and remains solid. In addition, like magnesium oxide, magnesium hydroxide becomes magnesium chloride and dissolves in an aqueous solution.

[0058] Therefore, by filtering this aqueous solution through a filter, the carbon powder can be recovered. In order to achieve high purity, the recovered carbon powder should be further washed with pure water or the like.

[0059] On the other hand, magnesium chloride is dissolved in the filtrate, so if the magnesium chloride is recovered and subjected to molten salt electrolysis, magnesium can be produced.

[0060] Specifically, when the water in the collected filtrate is evaporated, magnesium chloride hexahydrate precipitates as crystals, which are then collected.

[0061] Then, in order to remove moisture from the crystals, magnesium chloride hexahydrate is heated to a temperature of about 300°C to 600°C while hydrogen chloride gas is blown over it. In addition, the temperature is preferably set to 400°C to 550°C in terms of the reaction rate of the dehydration reaction and suppression of the production of magnesium oxide.

[0062] If you simply heat magnesium chloride hydrate to remove the water, it turns into magnesium oxide.

[0063] However, if heating is performed while hydrogen chloride gas is blown over the material, the reaction leading to magnesium oxide is inhibited and the dehydration reaction proceeds, resulting in anhydrous magnesium chloride.

[0064] The anhydrous magnesium chloride produced in this way can be heated to around 700°C, molten, and subjected to electrolysis to produce magnesium.

[0065] Therefore, it is possible to use magnesium oxide, which is an oxide of inorganic fuel in the combustion ash, as a material to produce magnesium, which can be used as inorganic fuel again, and if the inorganic fuel produced is used in the thermal power generation described above, it becomes a resource-circulating thermal power generation method.

[0066] In terms of recycling resources in this way, it is preferable that the oxides of the inorganic fuel contained in the combustion ash are of a single type, since this saves the effort of separating them.

[0067] Therefore, it is preferred that the inorganic fuel be made up of only a single inorganic substance, or a mixture of inorganic hydrides.

[0068] For example, if the inorganic substance is magnesium, the inorganic hydride mixed therewith should preferably be magnesium hydride.

[0069] On the other hand, the molten salt electrolysis method described above only uses electricity as energy, and therefore can be carried out using electricity that cannot be connected to a grid, such as that found in residual wind turbines, and can suppress the generation of carbon dioxide gases, which have an impact on global warming, including the overall resource circulation.

[0070] In the above, coal has been given as an example of an organic fuel, but similarly, any fuel that can be burned in a stoker-type boiler and generates carbon oxide gas (carbon monoxide gas, carbon dioxide gas, etc.) that acts as a combustion supporting gas for inorganic fuels during combustion can be used.

[0071] Therefore, for example, wood chips may be used as organic fuel. Since wood chips are made from wood that is renewable in nature, they are considered to be a carbon-neutral, sustainable fuel.

[0072] Therefore, when wood chips are used as an organic fuel, the carbon oxide gas (carbon dioxide gas, etc.) generated by its combustion is decomposed by the combustion of inorganic fuel, resulting in a thermal power generation method that does not emit carbon oxide gas, making this a carbon-negative power generation method.

[0073] Second embodiment FIG. 2 is a diagram for explaining a thermal power plant in which a thermal power generation method according to a second embodiment of the present invention is implemented. The thermal power plant of this embodiment is also substantially similar to the thermal power plant of the first embodiment, so a description of the same parts may be omitted.

[0074] The thermal power generation method of the present embodiment is different in that a hydrogenated inorganic fuel that is at least partially hydrogenated is used as the inorganic fuel. For example, a specific example is low-purity magnesium hydride, at least the surface of which is hydrogenated and has a layer of magnesium hydride.

[0075] In this case, the combustion reaction in the second combustion chamber B includes not only the combustion reaction of magnesium with the combustion supporting gas being carbon oxide gas (carbon dioxide gas) described in the first embodiment (see equation (1)), but also the combustion reaction of the magnesium hydride portion.

[0076] The combustion reaction of magnesium hydride (MgH2) begins with the reaction shown in formula (2) below, in which magnesium hydride is decomposed by heat into magnesium and hydrogen gas (H2). The magnesium produced by this reaction then undergoes the combustion reaction shown in formula (1). MgH2-heat → Mg+H2·····················(2)

[0077] In this case, the hydrogen gas generated by the decomposition of magnesium hydride is not consumed in the second combustion chamber B, but is discharged to the outside of the second combustion chamber B together with the exhaust gas discharged from the second combustion chamber B.

[0078] Therefore, in this embodiment, as indicated by the solid arrow, exhaust gas is first supplied through an exhaust pipe (not shown) to a hydrogen recovery unit H that recovers hydrogen gas, and the hydrogen gas is recovered there.

[0079] The recovered hydrogen gas is then supplied to the fuel cell F through a gas pipe (not shown) as indicated by the two-dot chain line arrow, where power is generated.

[0080] The recovered hydrogen gas may be temporarily stored in a hydrogen gas tank for storing hydrogen gas, and then sent to the fuel cell F from the hydrogen gas tank.

[0081] For example, the electric power generated by this fuel cell F is used as the electric power required for the operation of a thermal power plant that implements this thermal power generation method. Therefore, all of the power generated by the generator 1 can be used for power transmission.

[0082] Although the above description is given in the case where the inorganic fuel is at least partially hydrogenated magnesium, the same applies when the inorganic fuel is a mixture of magnesium and at least partially hydrogenated magnesium, that is, a mixture of an inorganic material and a hydrogenated inorganic material.

[0083] Third embodiment In the first and second embodiments, the case of a stoker type boiler has been described, but the present invention may also be applied to a thermal power generation method using a power generation boiler in the form of a pulverized coal combustion boiler, for example.

[0084] In this case, the first combustion chamber A may be provided with a general pulverized coal burner for burning pulverized coal.

[0085] In addition, the second combustion chamber B may have a stoker-type structure, but a powder combustion burner having a structure similar to that of a pulverized coal burner may be provided, and the inorganic fuel used may be pulverized into a powder suitable for combustion in the powder combustion burner.

[0086] In this case, since combustible inorganic substances become more flammable as they are powdered, it is preferable to use hydrogenated inorganic substances having at least a hydrogenated layer on the surface.

[0087] In this way, the hydrogenated film suppresses the reaction between the inorganic material and oxygen in the air and also protects it from ignition.

[0088] In addition, since the hydrogenated film is for protection purposes, when viewed as an inorganic hydrogenated material, it does not need to be a high-purity inorganic hydrogenated material, and it is sufficient if it is a low-purity inorganic hydrogenated material with a purity of 30 mass % or less.

[0089] In this way, by limiting the hydrogenation rate to a low purity hydrogenated inorganic material, the hydrogenation treatment time for treating the inorganic material in a hydrogen atmosphere can be significantly reduced, and production efficiency can be improved.

[0090] On the other hand, instead of the pulverized coal burner, the burner provided in the first combustion chamber A may be a burner for burning liquid fuel, and the organic fuel may be a petroleum-based liquid fuel (for example, heavy oil, light oil, etc.).

[0091] In this way, even if the organic fuel is a petroleum-based liquid fuel, it contains sulfur components and also generates soot, so the treatment of the exhaust gas discharged from the first combustion chamber A can be performed in the same manner as in the first embodiment.

[0092] In other words, the carbon dioxide gas may be recovered by a separation and recovery device that recovers the carbon dioxide gas from the exhaust gas that has passed through a denitration device, a dust collector, and a desulfurization device.

[0093] (Fourth embodiment) The organic fuel is not limited to those described so far (that is, fossil fuels other than liquefied natural gas), but may also be liquefied natural gas.

[0094] In this case, a gas combustion burner may be provided in the first combustion chamber A, but in the case of thermal power generation in which gas is burned, it is better to use a gas turbine in consideration of power generation efficiency and the like.

[0095] Therefore, as the fourth embodiment, a case where the organic fuel is liquefied natural gas and a gas turbine is used will be described.

[0096] In addition, liquefied natural gas is produced through a refining process from natural gas obtained from oil and gas fields, and does not contain any sulfur components, so no sulfur dioxide gas is generated, and no sulfur dioxide gas is generated when inorganic fuels are burned.

[0097] Therefore, when a gas combustion burner for burning liquefied natural gas is provided in the first combustion chamber A mentioned above, the desulfurization device described above may be omitted.

[0098] FIG. 3 is a diagram for explaining a thermal power plant in which the thermal power generation method of the present embodiment is implemented. In addition, since the thermal power plant in which the thermal power generation method of the present embodiment is implemented is similar in many respects to the thermal power plant described with reference to FIG. 1, a description of the similar points may be omitted.

[0099] As shown in FIG. 3, in this embodiment, a gas turbine G that is powered by the combustion of liquefied natural gas is added to drive the generator 1.

[0100] The liquefied natural gas, which is the organic fuel in this embodiment, is sent to the gas turbine G, rather than being sent from the organic fuel storage 3 to the combustion chamber 21 of the power generation boiler 2, in order to be combusted in the gas turbine G.

[0101] In addition, since the organic fuel storage tank 3 stores liquefied natural gas, it is a tank for storing liquefied gas.

[0102] Then, the exhaust gas containing carbon dioxide gas remaining after the liquefied natural gas is combusted in the gas turbine G is sent through an exhaust pipe (not shown) as indicated by the solid arrow, and then sent to a denitration device 5, and further to a dust collector 6. The carbon dioxide gas is separated and captured in a separation and capture device 8, where it is then released into the atmosphere via an exhaust fan 9.

[0103] On the other hand, the carbon dioxide gas recovered by the separation and recovery device 8 is supplied to the combustion chamber 21 of the power-generating boiler 2 via a storage tank 81.

[0104] In this embodiment, the liquefied natural gas, which is an organic fuel, is combusted in the gas turbine G, and does not need to be combusted in the combustion chamber 21 of the power boiler 2.

[0105] Therefore, unlike the first embodiment, the combustion chamber 21 is not divided into a first combustion chamber and a second combustion chamber, and the combustion chamber 21 is used only for burning inorganic fuel.

[0106] Then, the exhaust gas from the combustion chamber 21 passes through an exhaust pipe (not shown) and joins an exhaust pipe (not shown) between the gas turbine G and the denitration device 5, as indicated by a solid arrow.

[0107] In this embodiment, the exhaust gas containing fine powder that needs to be collected by the dust collector 6 is exhaust gas discharged from the combustion chamber 21, so the dust collector 6 is provided in the exhaust pipe (not shown) between the gas turbine G and the denitration device 5 until it joins the exhaust pipe (not shown), and the exhaust gas discharged from the gas turbine G may pass through the denitration device 5 without passing through the dust collector 6, and then be sent to the separation and recovery device 8 that separates and recovers carbon dioxide gas.

[0108] In addition, some gas turbines that use liquefied natural gas as fuel can suppress the generation of nitrogen oxides (NOx) to below environmental standards if the combustion temperature can be kept high, and some use a combustion supporting gas with a high oxygen concentration to suppress the generation of nitrogen oxides (NOx).In this case, the denitrification device 5 may be omitted.

[0109] Furthermore, in the case where the inorganic fuel contains hydrogenated inorganic matter, a hydrogen recovery device H and a fuel cell F may be provided as described with reference to FIG. 2, and in the case where a large amount of hydrogen is recovered, the fuel cell F may be replaced with a hydrogen gas turbine for power generation.

[0110] Although the thermal power generation method of the present invention has been described above through specific embodiments, the present invention is not limited to the specific embodiments, and appropriate modifications and improvements are also included in the technical scope of the present invention, which will be apparent to those skilled in the art from the description of the claims. [Explanation of symbols]

[0111] 1. Generator 2. Power generation boilers 21 Combustion chamber 22 Steam turbine 23 Piping 3. Organic Fuel Storage 4 Inorganic Fuel Storage 5 Denitration equipment 6 Dust collector 7 Desulfurization equipment 8 Separation and recovery device 81 Storage Tank 9 Exhaust fan F fuel cell H Hydrogen recovery equipment

Claims

1. A thermal power generation method utilizing the combustion of organic fuel and the combustion of inorganic fuel, The inorganic fuel is an inorganic material combustible with carbon dioxide gas as a combustion supporting gas, a hydrogenated inorganic material in which at least a part of the inorganic material is hydrogenated, or a mixture of the inorganic material and the hydrogenated inorganic material, A thermal power generation method comprising the steps of: burning the inorganic fuel using carbon oxide gas in exhaust gas generated by combustion of the organic fuel as a combustion supporting gas, and solidifying carbon in the carbon oxide gas.

2. The thermal power generation method according to claim 1 , wherein the inorganic substance is lithium, magnesium, aluminum, or a mixture containing two or more of lithium, magnesium, and aluminum.

3. The thermal power generation method according to claim 2 , wherein the inorganic substance is magnesium.

4. The organic fuel is a fossil fuel other than liquefied natural gas; the carbon oxide gas used as the combustion supporting gas for the combustion of the inorganic fuel is carbon dioxide gas; 4. The thermal power generation method according to claim 3, wherein the carbon dioxide gas is recovered from the exhaust gas after passing through a denitration device, a dust collector, and a desulfurization device, through a carbon dioxide gas separation and recovery device.

5. the organic fuel is liquefied natural gas; the carbon oxide gas used as the combustion supporting gas for the combustion of the inorganic fuel is carbon dioxide gas; The thermal power generation method according to claim 3 , wherein the carbon dioxide gas is recovered from the exhaust gas through a carbon dioxide gas separation and recovery device.

6. 4. The thermal power generation method according to claim 3, wherein the solidified carbon is recovered as combustion ash together with oxides of the inorganic fuel generated by combustion of the inorganic fuel, the solidified carbon is separated from the combustion ash, and the solidified carbon is used as a raw material for a carbon material.

7. The thermal power generation method according to claim 6 , further comprising the step of: producing the inorganic fuel again using the oxide as a material, and using the inorganic fuel for thermal power generation.

8. In order to maintain a positive pressure in a combustion chamber in which the inorganic fuel is burned, a flow rate of the carbon dioxide gas supplied to the combustion chamber is adjusted. The thermal power generation method according to claim 1.

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