Power generation method and power generation equipment

Abstract

To provide a power generation method and power generation equipment that leverage the technology developed in coal thermal power generation to reduce carbon dioxide emissions.SOLUTION: In a combustion chamber 21 of a power generation boiler 2, an inorganic solid fuel and a coal gasification gas as an assistive combustion gas are burnt.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] 2. Description of the Related Art Coal-fired power generation systems equipped with power generation boilers are generally known (see, for example, Non-Patent Document 1).

[0003] However, even though Japan possesses some of the world's leading coal-fired power generation technology, opportunities for utilizing this technology are being lost due to the issue of carbon dioxide being emitted when coal is burned.

[0004] One technology that could provide a solution to these problems is carbon dioxide capture and storage (CCS), which involves separating and capturing carbon dioxide from exhaust gases from thermal power plants and storing the captured carbon dioxide.

[0005] For example, Non-Patent Document 2 introduces the efforts of Tomakomai City, Hokkaido, regarding CCS, specifically explaining that carbon dioxide is separated and captured from exhaust gases from thermal power plants, and the captured carbon dioxide is injected and stored deep underground beneath the seabed about 3 to 4 km from the coast. It is believed that the carbon dioxide injected deep underground in this way is stored stably for a long period of time, and dissolves in salt water over a long period of time and becomes minerals in the gaps between rocks.

[0006] However, there are many restrictions to this type of storage, such as the fact that the stratum must have gaps large enough to store carbon dioxide, and that it must 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 power generation method and power generation facility that utilizes technology cultivated in coal-fired power generation and reduces carbon dioxide emissions. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention is realized by the following configuration. (1) In the power generating method of the present invention, an inorganic solid fuel and a coal gasification gas serving as a combustion supporting gas are combusted in a combustion chamber of a power generating boiler.

[0010] (2) In the above configuration (1), the inorganic solid fuel is at least one of lithium, magnesium, boron, and aluminum.

[0011] (3) In the above configuration (1), the inorganic solid fuel is at least one of lithium, magnesium, and aluminum, and an oxide that is a combustion product of the inorganic solid fuel is reduced and repeatedly used as the inorganic solid fuel.

[0012] (4) In the above configuration (1), the inorganic solid fuel is at least one of lithium, magnesium, boron, and aluminum, which is at least partially hydrogenated.

[0013] (5) In the above configuration (1), the inorganic solid fuel is at least one of lithium, magnesium, and aluminum, which are at least partially hydrogenated, and the oxides that are the combustion products of the inorganic solid fuel are reduced and hydrogenated, and are repeatedly used as the inorganic solid fuel.

[0014] (6) In the above configuration (1), the combustion supporting gas is a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility.

[0015] (7) In the above configuration (1), the combustion supporting gas is a fuel gas obtained by refining, in a gas refining facility, a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility.

[0016] (8) In the configuration of (1) above, the combustion supporting gas is an exhaust gas discharged from a gas refining facility that refines coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility into a fuel gas, and combusts the fuel gas in a combustor.

[0017] (9) In the configuration of (1) above, the combustion supporting gas is a dry gas obtained by refining coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility in a gas refining facility to produce a fuel gas, and then combusting the fuel gas in a combustor to discharge an exhaust gas from which moisture has been separated.

[0018] (10) In the above configuration (1), the combustion supporting gas is a shift gas obtained by purifying a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility into a fuel gas in a gas refining facility, and subjecting the fuel gas to a water-gas shift reaction.

[0019] (11) In the above configuration (1), the combustion supporting gas is carbon dioxide gas remaining after hydrogen is separated from a shift gas obtained by subjecting a water-gas shift reaction of a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility to a fuel gas refined in a gas refinery facility and the fuel gas is subjected to a water-gas shift reaction.

[0020] (12) In the power generation facility of the present invention, inorganic solid fuel and coal gasification gas as a combustion supporting gas are combusted in a combustion chamber of a power generation boiler, and the amount of the combustion supporting gas supplied to the combustion chamber is adjusted to maintain the pressure in the combustion chamber at a predetermined pressure. Effect of the Invention

[0021] According to the present invention, it is possible to provide a power generation method and power generation facility that reduce carbon dioxide emissions by utilizing technology cultivated in coal-fired power generation. [Brief description of the drawings]

[0022] [Figure 1] 1 is a system diagram for explaining a schematic configuration of an integrated coal gasification combined cycle power generation facility according to an embodiment. [Diagram 2] 1 is a system diagram for explaining a schematic configuration of a coal gasification fuel cell combined cycle power generation facility according to an embodiment. [Diagram 3] FIG. 1 is a diagram for explaining a schematic configuration of a power plant for carrying out a power generation process according to an embodiment of the present invention. [Figure 4] FIG. 1 is a diagram for explaining a schematic configuration of an apparatus for carrying out a hydrogenation step according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter, referred to as embodiments) will be described with reference to the accompanying drawings.

[0024] As an example, the power generation facility according to the present invention may be installed alongside an integrated coal gasification combined cycle (IGCC) facility or an integrated coal gasification fuel cell combined cycle (IGFC) facility. First, an integrated coal gasification combined cycle and an integrated coal gasification fuel cell combined cycle to which the power generation facility according to the present invention may be installed will be described. An integrated coal gasification combined cycle and an integrated coal gasification fuel cell combined cycle are also referred to as "coal gasification power generation facilities."

[0025] (Integrated coal gasification combined cycle power generation (IGCC)) FIG. 1 is a system diagram for explaining a schematic configuration of an integrated coal gasification combined cycle power generation facility 100 according to an embodiment.

[0026] The integrated coal gasification combined cycle power generation facility 100 is a power generation facility that burns coal gasification gas produced in a coal gasification facility 101 in a combustor 103 to drive a gas turbine 104 to obtain electric power, and also recovers exhaust heat from the gas turbine 104 to generate steam to drive a steam turbine 107 to obtain electric power. The integrated coal gasification combined cycle power generation facility 100 is a well-known mechanism and will not be described in detail, but the general configuration (particularly the configuration related to the present invention) is as follows.

[0027] The coal gasification facility 101 includes a coal gasifier, receives supply of coal and an oxidant, and produces coal gasification gas by gasifying the coal through a reaction of the oxidant. The oxidant supplied to the coal gasifier of the coal gasification facility 101 is an oxygen (O2)-containing gas, the main components of which may be oxygen, oxygen and nitrogen (N2), or air. The coal gasification gas contains carbon monoxide (CO) and hydrogen (H2) as main components.

[0028] The coal gasification facility 101 includes a dust remover and a heat exchanger, and performs dust removal treatment on the coal gasification gas produced in the coal gasification furnace and adjusts the coal gasification gas to a predetermined temperature. The coal gasification gas produced by the coal gasification facility 101 is sent to a gas purification facility 102.

[0029] Coal gasification gas contains combustible components such as carbon monoxide (CO) and hydrogen (H2), as well as impurities, sulfur, etc. The gas purification facility 102 purifies the coal gasification gas supplied from the coal gasification facility 101 by removing impurities, sulfur, etc.

[0030] The gas purification equipment 102 includes, for example, a dust filter that removes solid impurities in the coal gasification gas, a halide removal device equipped with a halide absorbent that chemically reacts with halides contained in the coal gasification gas, and a desulfurization device equipped with a metal oxide desulfurization agent that chemically reacts with sulfur compounds contained in the coal gasification gas. The coal gasification gas (referred to as "fuel gas") purified by the gas purification equipment 102 is sent to the combustor 103.

[0031] The combustor 103 combusts fuel gas (CO, H2) supplied from the gas purification facility 102, and supplies high-temperature, high-pressure gas (referred to as "combustion gas") to the gas turbine 104. Oxygen (O2) is supplied to the combustor 103 as an oxidizing agent. The high-temperature, high-pressure combustion gas discharged from the combustor 103 is sent to the gas turbine 104. The combustion gas contains carbon dioxide (CO2) and moisture (H2O).

[0032] The gas turbine 104 expands the high-temperature, high-pressure combustion gas supplied from the combustor 103 to rotate the turbine, thereby driving a generator 105 .

[0033] The heat recovery steam generator 106 recovers heat from the exhaust gas discharged from the gas turbine 104 to generate steam. The exhaust gas from which heat has been recovered in the heat recovery steam generator 106 is sent to a compressor 110.

[0034] The steam turbine 107 uses steam generated in the heat recovery steam generator 106 to rotate the turbine and drive a generator 108 .

[0035] The recovery device 109 separates moisture (H2O) from at least a portion of the exhaust gas (CO2, H2O) discharged from the heat recovery boiler 106, and recovers carbon dioxide (CO2). The recovery device 109 separates (in other words, removes) moisture from the exhaust gas, for example, by drying the exhaust gas. The exhaust gas (CO2) from which moisture has been separated / removed is referred to as "dry gas."

[0036] The compressor 110 receives the exhaust gas discharged from the heat recovery boiler 106, compresses the exhaust gas, and supplies it to the combustor 103. At this time, the recovery device 109 recovers excess carbon dioxide from the exhaust gas discharged from the heat recovery boiler 106.

[0037] (Integrated coal gasification fuel cell combined cycle power plant (IGFC)) FIG. 2 is a system diagram for explaining a schematic configuration of a coal gasification fuel cell combined cycle power generation facility 120 according to an embodiment.

[0038] The coal gasification fuel cell combined cycle power generation facility 120 uses the coal gasification gas produced in the coal gasification facility 101 as an anode (fuel) supplied to the anode electrode (fuel electrode; not shown) of the fuel cell 124, supplies an oxidant to the cathode electrode (air electrode, oxygen electrode; not shown) of the fuel cell 124 to generate electricity through an electrochemical reaction, and at the same time, drives the gas turbine 104 with the exhaust gas discharged from the fuel cell 124 to obtain electric power, and drives the steam turbine 107 with steam generated by recovering exhaust heat from the gas turbine 104 to obtain electric power. The coal gasification fuel cell combined cycle power generation facility 120 is a well-known mechanism, so a detailed description will be omitted, but the outline of the configuration (particularly the configuration related to the present invention) is as follows. In addition, in the coal gasification fuel cell combined cycle power generation facility 120, the same components as those of the above-mentioned coal gasification combined cycle power generation facility 100 are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

[0039] The shift reaction equipment 121 generates hydrogen and carbon dioxide by reacting carbon monoxide and water (specifically, for example, steam) contained in the fuel gas obtained after the coal gasification gas produced in the coal gasification equipment 101 is refined by the gas refining equipment 102. Specifically, the shift reaction equipment 121 generates hydrogen (H2) and carbon dioxide (CO2) by reacting carbon monoxide (CO) with water (H2O) using the water-gas shift reaction (see reaction formula 1 below). CO + H2O → H2+ CO2(1)

[0040] The gas after the water-gas shift reaction (CO 2 , H 2 ; referred to as “shifted gas”) produced by the shift reaction facility 121 is sent to a separation facility 122 .

[0041] The separation equipment 122 separates hydrogen (H2) from the components of the shift gas (CO2, H2) supplied from the shift reaction equipment 121, and supplies the hydrogen (H2) to the fuel cell 124. The gas remaining after hydrogen is separated from the shift gas is carbon dioxide (CO2) gas.

[0042] The compressor 123 compresses the air and supplies it to the fuel cell 124 .

[0043] The fuel cell 124 receives a supply of hydrogen from the separation equipment 122 and a supply of compressed air from a compressor 123. Hydrogen as fuel is sent to the anode electrode of the fuel cell 124, and compressed air as an oxidant is sent to the cathode electrode of the fuel cell 124, where electricity is generated by an electrochemical reaction.

[0044] The anode gas and cathode gas after the reaction in the fuel cell 124 are combusted in a fuel cell rear stage combustor 125 to become high temperature and high pressure gas (ie, combustion gas), which is then supplied to the gas turbine 104 .

[0045] The gas turbine 104 rotates the turbine by expanding high-temperature, high-pressure combustion gas supplied from the fuel cell rear-stage combustor 125 , thereby driving the generator 105 .

[0046] (Resource-recycling power generation facilities) The power generation method of the embodiment of the present invention includes a power generation process in which fuel is combusted in the combustion chamber 21 of the power generation boiler 2 to generate power, and a resource regeneration process in which raw materials for fuel are produced (in other words, regenerated) from the combustion ash generated by the combustion.

[0047] (Power generation process) The power generation process is a process carried out at a power plant, but the technology used there utilizes technology that has been developed in coal-fired power generation (specifically, burning inorganic solid fuel powder instead of pulverized coal), so explanations of similarities with conventional technologies may be omitted.

[0048] FIG. 3 is a diagram for explaining a schematic configuration of a power plant 10 for carrying out a power generation process according to an embodiment of the present invention.

[0049] In the power generation method of the embodiment according to the present invention, inorganic solid fuel and coal gasification gas as a combustion supporting gas are combusted in the combustion chamber 21 of the power generation boiler 2, and in particular, the combustion supporting gas is coal gasification gas produced in the coal gasification facility 101 of the coal gasification power generation facility.

[0050] As shown in Figure 3, the power plant 10 includes a generator 1, a power generation boiler 2 that drives the generator 1, a fuel storage tank 3 that stores fuel to be supplied to the power generation boiler 2, an auxiliary fuel storage tank 4 that stores auxiliary fuel to be supplied to the power generation boiler 2, a denitrification device 5 that renders harmless (in other words, removes) nitrogen oxides (NOx) contained in the exhaust gas discharged from the power generation boiler 2, a dust collector 6 that recovers combustion ash contained in the exhaust gas that has passed through the denitrification device 5, and a combustion ash storage tank 7 that stores the combustion ash.

[0051] 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 the condenser 9 back to the combustion chamber 21.

[0052] In addition, a water supply pump 24 is provided midway through the pipe 23 connecting the condenser 9 and the combustion chamber 21, and sends the water that has been returned to a liquid state in the condenser 9 to the combustion chamber 21 side.

[0053] The combustion chamber 21 is equipped with a powder combustion burner 31 that burns powdered fuel supplied from the fuel storage tank 3, and an auxiliary combustion burner 41 that burns liquid fuel (e.g., heavy oil, light oil, etc.) supplied from the auxiliary fuel storage tank 4.

[0054] In the present invention, the combustion of the powdered fuel in the combustion chamber 21 is preferably carried out in an oxygen-free environment (in other words, in the atmosphere). Even if the atmosphere in the combustion chamber 21 contains oxygen, the oxygen concentration is preferably adjusted to a concentration low enough to enable the production of carbon (C) as a combustion product. In other words, the oxygen concentration is preferably adjusted to a low level at which the reaction between magnesium and oxygen is not dominant (in other words, not preferred) compared to the reaction between magnesium and the combustion supporting gas in the present invention (e.g., carbon monoxide, carbon dioxide).

[0055] The powder combustion burner 31 may be, for example, similar to a pulverized coal burner used in coal-fired power generation, and the supply system that supplies powdered fuel and combustion supporting gas to the powder combustion burner 31 may also be similar to that used in coal-fired power generation.

[0056] The auxiliary combustion burner 41 is a burner for obtaining auxiliary heat until the temperature in the combustion chamber 21 rises and the combustion in the powder combustion burner 31 becomes stable, and this may be similar to that used in coal-fired power generation.

[0057] After the combustion of the powder combustion burner 31 becomes stable, there is no need for auxiliary heating power from the auxiliary combustion burner 41. And since a thermal power plant basically operates without being shut down, the amount of carbon dioxide generated by the auxiliary heating power, which is used only at the start of operation, is almost negligible.

[0058] Magnesium (Mg) is stored as a powder fuel that does not emit carbon dioxide when burned, which is the inorganic solid fuel of the present invention, in the fuel storage 3. The magnesium stored in the fuel storage 3 may be magnesium hydride (MgH2) having at least a hydrogenated layer on its surface, or a mixture of magnesium and magnesium hydride.

[0059] Magnesium (including magnesium hydride; the same applies below) as an inorganic solid fuel is preferably adjusted to a particle size of 150 μm or less. However, since magnesium is not perfectly spherical, a particle size of 150 μm or less here means a particle size that can pass through a sieve with a mesh opening of about 0.16 mm, for example.

[0060] Here, the pulverized coal used in pulverized coal burners used in coal-fired power generation is generally 150 μm or less, and by making the particle size of the magnesium 150 μm or less, there is an advantage that a burner with a similar structure to the pulverized coal burner can be used as the powder combustion burner 31.

[0061] In the powder combustion burner 31, magnesium mixed with a combustion supporting gas is burned.

[0062] As the combustion supporting gas supplied to the powder combustion burner 31, carbon monoxide or carbon dioxide generated in the system of the above-mentioned coal gasification combined cycle power generation plant 100 may be supplied, or carbon monoxide or carbon dioxide generated in the system of the above-mentioned coal gasification fuel cell combined cycle power generation plant 120 may be supplied.

[0063] A) The combustion reaction (including the generation of heat; the same applies below) between magnesium (Mg) and carbon monoxide (CO) in the coal gasification gas (CO, H2) discharged from the coal gasification equipment 101 of the integrated coal gasification combined cycle power plant 100 or the integrated coal gasification fuel cell combined cycle power plant 120 or the fuel gas (CO, H2) discharged from the gas purification equipment 102 is as shown in the following reaction formula 2. Also, the combustion reaction between magnesium hydride (MgH2) and carbon monoxide is as shown in the following reaction formula 3. Note that magnesium oxide (MgO) and carbon (C) produced by the combustion reaction are solids (specifically, powders). Mg + CO → MgO + C (2) MgH2+ CO → MgO + H2+ C (3)

[0064] A) The combustion reaction between magnesium (Mg) and carbon dioxide (CO2) in the combustion gas (CO2, H2O) discharged from the combustor 103 of the integrated coal gasification combined cycle power generation facility 100 is as shown in the following reaction formula 4. The combustion reaction between magnesium hydride (MgH2) and carbon dioxide is as shown in the following reaction formula 5. In addition, the combustion reaction between magnesium and moisture (H2O) is as shown in the following reaction formula 6. The combustion reaction between magnesium hydride (MgH2) and moisture is as shown in the following reaction formula 7. 2Mg + CO2 → 2MgO + C (4) 2MgH2+ CO2→ 2MgO + 2H2+ C (5) Mg + H2O → MgO + H2(6) MgH2+ H2O → MgO + 2H2(7)

[0065] C) The combustion reaction between magnesium (Mg) and carbon dioxide (CO2) gas (i.e., dry gas) discharged from the recovery device 109 of the integrated coal gasification combined cycle power generation facility 100 is as shown in the following reaction formula 8. Also, the combustion reaction between magnesium hydride (MgH2) and carbon dioxide is as shown in the following reaction formula 9. 2Mg + CO2 → 2MgO + C (8) 2MgH2+ CO2→ 2MgO + 2H2+ C (9)

[0066] D) The combustion reaction between magnesium (Mg) and carbon dioxide (CO2) in the shift gas (CO2, H2) discharged from the shift reaction equipment 121 of the coal gasification fuel cell combined cycle power generation equipment 120 is as shown in the following reaction formula 10. In addition, the combustion reaction between magnesium hydride (MgH2) and carbon dioxide is as shown in the following reaction formula 11. 2Mg + CO2 → 2MgO + C (10) 2MgH2+ CO2→ 2MgO + 2H2+ C (11)

[0067] E) The combustion reaction between magnesium (Mg) and carbon dioxide (CO2) obtained after hydrogen (H2) is separated from the shift gas (CO2, H2) in the separation process in the separation equipment 122 of the coal gasification fuel cell combined cycle power generation equipment 120 is shown in the following reaction formula 12. The combustion reaction between magnesium hydride (MgH2) and carbon dioxide is shown in the following reaction formula 13. 2Mg + CO2 → 2MgO + C (12) 2MgH2+ CO2→ 2MgO + 2H2+ C (13)

[0068] As described above, magnesium oxide (MgO) and carbon (C) are generated in the combustion reaction in the powder combustion burner 31, and carbon dioxide (CO2) is not generated during combustion for power generation. However, for example, if the combustion supporting gas supplied to the powder combustion burner 31 contains moisture, the water may react with part of the magnesium oxide, resulting in magnesium hydroxide (Mg(OH)2) being contained in the combustion ash.

[0069] Here, the combustion reaction between magnesium and the combustion supporting gas is a pressure reducing reaction in which a solid is produced by a reaction between a solid and a gas, and since the pressure in the combustion chamber 21 may decrease when the inorganic solid fuel and the combustion supporting gas are completely combusted in the combustion chamber 21, the amount of the combustion supporting gas supplied to the combustion chamber 21 may be adjusted in order to maintain the pressure in the combustion chamber 21 at a predetermined pressure (for example, about 1 atmosphere, or about the range of pressure allowed for the pressure in the combustion chamber 21). In this case, for example, a pressure adjustment system in which gas discharged to the outside of the combustion chamber 21 without contributing to the reaction in the combustion chamber 21 is collected and then reintroduced into the combustion chamber 21 may be provided separately from the supply system and combustion system associated with the powder combustion burner 31.

[0070] In order to deal with cases in which nitrogen oxides (NOx) are generated during combustion in the combustion chamber 21, a denitrification device 5 is provided midway through the exhaust pipe 8, which sends the exhaust gas discharged from the combustion chamber 21 to a dust collector 6, in order to render the nitrogen oxides in the exhaust gas discharged from the combustion chamber 21 harmless (in other words, to remove them).

[0071] The denitration device 5 may be similar to a denitration device used in coal-fired power plants, which has the function of decomposing nitrogen oxides into harmless nitrogen and water by adding ammonia (NH3) to the exhaust gas and passing it through a catalyst layer.

[0072] The exhaust gas after passing through the denitrification device 5 does not contain any harmful gases, but does contain combustion ash (specifically, powdered magnesium oxide, magnesium hydroxide, and carbon) generated during combustion that has an extremely small particle size. For this reason, the exhaust pipe 8 is connected to the dust collector 6, and after the combustion ash is collected by the dust collector 6, the exhaust gas is released into the atmosphere.

[0073] The dust collector 6 may be the same as a dust collector used in coal-fired power generation, and specifically may be, for example, an electric dust collector.

[0074] In the example shown in FIG. 3, an exhaust device 81 is provided downstream of the dust collector 6, and this allows the exhaust gas in the combustion chamber 21 to pass through the denitration device 5 and the dust collector 6 and be released into the atmosphere.

[0075] On the other hand, in coal-fired power generation, coal is used as fuel, so the sulfur components contained in the coal are contained in the exhaust gas. For this reason, in coal-fired power generation, a desulfurization device is further installed before the exhaust gas is released into the atmosphere. In contrast, in the present invention, magnesium does not contain sulfur components, so there is an advantage that a desulfurization device is not required.

[0076] In addition, in coal-fired power plants, since the exhaust gas contains carbon dioxide, it is necessary to release the exhaust gas into the atmosphere from a tall chimney. In contrast, in the present invention, such a tall chimney is not necessary.

[0077] The combustion ash deposited at the bottom of the combustion chamber 21 and the combustion ash collected by the dust collector 6 are collected in the combustion ash storage 7 and are repeatedly regenerated into magnesium through a resource regeneration process described below for resource circulation. The regenerated magnesium is used as an inorganic solid fuel supplied to the powder combustion burner 31.

[0078] In addition, in coal-fired power generation, coal residue accumulates at the bottom of the combustion chamber and is also contained in the exhaust gas, so a dust collector is used, and the mechanism for recovering magnesium combustion ash may be similar to the mechanism used in coal-fired power generation.

[0079] As can be seen from the above explanation, if magnesium with a particle size of 150 μm or less is used as fuel, it is extremely compatible with the coal-fired power generation technology that has been developed so far, in which pulverized coal is burned in a pulverized coal burner to generate electricity, and a power generation process with reduced carbon dioxide emissions can be carried out.

[0080] (Resource recycling process) Next, a resource recovery process will be described in which magnesium is regenerated using as a starting material an oxide of magnesium (specifically, magnesium oxide) contained in the combustion ash generated as a combustion product in the power generation process.

[0081] Regarding magnesium hydroxide (Mg(OH)2) contained in the combustion ash, when heated, a dehydration reaction occurs and it becomes magnesium oxide (MgO) as shown in the following reaction formula 14. Therefore, magnesium oxide can be considered as the starting material for the resource recovery process. Mg(OH)2 → MgO + H2O (14)

[0082] The procedure for producing magnesium from the starting material, magnesium oxide, can be divided into a chlorination process, in which magnesium chloride is produced using magnesium oxide, which is combustion ash, as a material, and a molten salt electrolysis process, in which magnesium is produced using the magnesium chloride produced in the chlorination process as a material.

[0083] (Chlorination process) The chlorination process is a process in which magnesium oxide, which is combustion ash, is used as a material to produce magnesium chloride, which is used in the subsequent molten salt electrolysis process.

[0084] In the chlorination process, powdered magnesium oxide (MgO) and carbon (C), which are combustion ash, are first added to hydrogen chloride (HCl) water. The magnesium oxide reacts in the hydrogen chloride water to become magnesium chloride (MgCl2) as shown in the following reaction formula 15. The magnesium chloride produced by the reaction is a substance that has high solubility in water, so it will dissolve if the hydrogen chloride water has a sufficient amount of water. MgO + 2HCl → MgCl2+ H2O (15)

[0085] On the other hand, carbon does not react or dissolve, so it remains in powder form in the hydrogen chloride water. Therefore, by filtering the hydrogen chloride water in which magnesium chloride is dissolved, the carbon in the combustion ash can be recovered.

[0086] The carbon recovered by the above method is of high purity and is useful as an industrial material, and is particularly useful in fields where high-purity carbon materials are required.

[0087] After filtering the carbon, anhydrous magnesium chloride is recovered from the hydrogen chloride water. For example, anhydrous magnesium chloride can be recovered from hydrogen chloride water by heating the hydrogen chloride water while blowing hydrogen chloride gas into it. This method is well known and will not be described in detail.

[0088] As a method for recovering anhydrous magnesium chloride from hydrogen chloride water, hydrogen chloride water (wherein magnesium chloride is dissolved in the form of a hexahydrate) may be heated in a nitrogen atmosphere to remove water and obtain anhydrous magnesium chloride, or hydrogen chloride may be removed to obtain magnesium oxide, which may then be further processed.

[0089] In the above case, magnesium oxide may be converted to magnesium chloride by reacting magnesium oxide with hydrogen chloride gas at a temperature of about 300 to 600° C. according to the following reaction formula 16. MgO + 2HCl → MgCl2+ H2O (16)

[0090] In the above case, magnesium oxide may be converted to magnesium chloride by reacting magnesium oxide with ammonium chloride (NH4Cl) at a temperature of about 300 to 600°C according to the reaction represented by the following reaction formula 17. MgO + 2NH4Cl → MgCl2+ H2O + 2NH3(17)

[0091] In the above case, for magnesium oxide, alternatively, a molar ratio of magnesium oxide and ammonium chloride is 1:3 and the reaction of the following reaction formula 18 is caused at a temperature of about 400 ° C. to generate an ammonium carbohydrate hydrate, and then the ammonium carbohydrate hydrate is heated to a temperature slightly lower than the sublimation temperature of ammonium chloride (for example, a temperature about 5 to 20 ° C. lower than the sublimation temperature) under ammonia gas stream to cause a dehydration reaction of the following reaction formula 19 to remove moisture, and further heated to a temperature higher than the sublimation temperature of ammonium chloride (for example, around 400 ° C.) under dry nitrogen stream to cause the reaction of the following reaction formula 20 to remove the ammonium chloride portion to form anhydrous magnesium chloride. MgO+3NH4Cl→MgCl2·NH4Cl·H2O+2NH3(18) MgCl2·NH4Cl·H2O→MgCl2·NH4Cl+H2O (19) MgCl2·NH4Cl→MgCl2+NH3+HCl (20)

[0092] (Molten salt electrolysis process) The molten salt electrolysis process is a process in which magnesium is produced by electrolysis using anhydrous magnesium chloride produced in the chlorination process as a material, and is a method used for producing magnesium.

[0093] The outline of the molten salt electrolysis process is as follows: for example, magnesium chloride is heated to a temperature of around 700°C in a brick furnace to melt the magnesium chloride.

[0094] At least a pair of electrodes are installed inside the brick furnace, and when a power source is connected between these electrodes and a voltage of 2.5V or more is applied, chlorine (Cl2) gas is generated at the anode and magnesium is produced at the cathode.

[0095] Hydrogen chloride gas is produced by reacting hydrogen gas with chlorine gas, so hydrogen chloride gas may be produced using chlorine gas generated in the molten salt electrolysis process as a material and used in the chlorination process.

[0096] (Atomization process) The atomization process is a process for converting the magnesium produced in the molten salt electrolysis process into powdered magnesium, and may be carried out using a general grinding machine or a fine powder manufacturing device called a gas atomizer.

[0097] When a pulverizing device is used to carry out the microparticulation step, it is preferable to carry out the pulverization step in two stages in consideration of pulverization efficiency.

[0098] Specifically, the micronization process is preferably carried out in two stages: a coarse crushing process in which the magnesium is coarsely crushed to a particle size of about 180 to 800 μm using a device with a high crushing speed, although not to the micronized level; and a fine crushing process in which the magnesium crushed in the coarse crushing process is crushed to a particle size of 150 μm or less.

[0099] The particle size in the atomization step does not mean an exact sphere, and the particle size in the coarse pulverization step is, for example, a particle size that can pass through a sieve with a mesh opening of about 0.8 mm.

[0100] Here, when magnesium is roughly crushed, the fact that magnesium is a soft metal does not cause any problems, but when it is finely crushed, there is a problem that magnesium particles stick together during the crushing process, making it difficult to form a fine powder. For this reason, it is preferable to add a crushing aid to the coarsely crushed magnesium in the fine crushing process.

[0101] As the grinding aid, for example, stearic acid or the like can be used, but it is preferable to use a powder of an inorganic compound. Specifically, for example, by using magnesium oxide, which is a powder of an inorganic compound, as the grinding aid, it becomes possible to use a part of the combustion ash as the grinding aid, since it has the same composition as the combustion ash.

[0102] (Hydrogenation process) As described above, magnesium hydride having at least a hydrogenated layer on its surface may be used as the inorganic solid fuel in the present invention. Therefore, the magnesium atomized in the atomization process may be hydrogenated (this process is referred to as the "hydrogenation process").

[0103] Here, if magnesium comes into contact with oxygen after being pulverized, an oxide film will form on the surface, significantly reducing the reaction efficiency. For this reason, the magnesium pulverized in the pulverization process must be handled in such a way that it does not come into contact with oxygen until the hydrogenation process is completed.

[0104] A method for performing the hydrogenation step without exposing the mixture to the outside air will be described with reference to FIG. 4, which is a diagram illustrating the configuration of an apparatus for performing the hydrogenation step.

[0105] As shown in FIG. 4, the apparatus 300 for carrying out the hydrogenation process includes a heating vessel 310 for containing micronized magnesium and reacting it with hydrogen, a heater 320 for heating the heating vessel 310, and a pipe 315 detachably connected to the inlet 311 of the heating vessel 310.

[0106] Heating vessel 310 is provided with a valve 314 at a conduit section 313 extending from inlet 311 to heating section 312, and when valve 314 is closed, the vessel becomes airtight.

[0107] Although not shown, the pipe 315 is connected to a hydrogen gas supply system, an argon gas supply system, and a vacuum pump.

[0108] The heating vessel 310 also serves as a recovery vessel for recovering the magnesium pulverized in the fine pulverization process.

[0109] As described above, the fine grinding process is performed under an argon gas atmosphere, and before the heating container 310 is removed from the grinding device performing the fine grinding process, the valve 314 is closed and the magnesium recovered in the heating container 310 is connected to the device 300 shown in Figure 4 in an argon-filled state.

[0110] Then, before the valve 314 is opened, a vacuum is drawn, and the air existing in the pipe 315 and upstream side of the valve 314 is exhausted, and then the valve 314 is opened and the argon gas in the heating unit 312 is exhausted.

[0111] Thereafter, the heater 320 is driven to heat the temperature inside the heating section 312 to a temperature suitable for hydrogenation (specifically, 180°C to 220°C), and hydrogen gas is supplied to the heating container 310 to perform the hydrogenation process (see reaction formula 21 below). Mg + H2 → MgH2(21)

[0112] Here, magnesium hydride with a hydrogenation rate of about 20% by mass has almost the same calorific value per weight as coal, so low-purity magnesium hydride can be used as a fuel to replace coal (in other words, to replace coal). Furthermore, magnesium becomes more flammable when it is turned into fine powder, and is generally treated as a hazardous material under the Fire Service Act. On the other hand, magnesium hydride is less flammable because it has been hydrogenated, so even in fine powder form it does not qualify as a hazardous material under the Fire Service Act. Therefore, it is sufficient for magnesium hydrogenation to achieve a hydrogenation rate that does not qualify it as a hazardous material in terms of transportation, storage, etc.

[0113] The hydrogenation of magnesium does not proceed in proportion to the treatment time, but rather the rate of progress slows down significantly as the purity increases. Therefore, if low-purity magnesium hydride is produced with a hydrogenation rate of 30 mass% or less (e.g., about 20 mass%) in which at least the surface side is hydrogenated, the time required for the hydrogenation process can be significantly reduced, making it possible to significantly increase productivity.

[0114] After the hydrogenation process, the heater 320 is turned off, and after cooling, the hydrogen gas in the heating vessel 310 is replaced with argon gas, and low-purity magnesium hydride is taken out. The low-purity magnesium hydride thus produced, in which at least the surface side has been hydrogenated to a hydrogenation rate of 30 mass % or less (for example, about 20 mass %), is used again as fuel in the power generation process.

[0115] In addition, as the inorganic solid fuel in the present invention, magnesium hydride having a high hydrogenation rate may be used, or a mixture of magnesium and magnesium hydride may be used.

[0116] (Action and effect) According to the power generation method and power plant 10 of the embodiment, inorganic solid fuel (specifically, magnesium, magnesium hydride) and coal gasification gas as a combustion supporting gas are combusted in the combustion chamber 21 of the power generation boiler 2, so that no carbon dioxide is generated during power generation, and it is possible to realize resource-circulating thermal power generation in which magnesium resources are circulated. Furthermore, according to the power generation method and power plant 10 of the embodiment, the carbon dioxide emitted from a coal gasification power generation facility (specifically, a coal gasification combined cycle power generation facility, a coal gasification fuel cell combined cycle power generation facility) is used as a combustion supporting gas to generate power, thereby making it possible to significantly reduce the environmental impact of coal-fired power generation.

[0117] According to the power generation method and power plant 10 of the embodiment, it is possible to utilize a mechanism similar to that used in coal-fired power generation, and therefore it is possible to reduce carbon dioxide emissions by utilizing the technology cultivated in coal-fired power generation.

[0118] According to the power generation method and power plant 10 of the embodiment, and also because the resource recycling process is composed only of equipment that runs on electricity, it is possible to perform fuel regeneration production using only surplus electricity that cannot be connected to a grid. Therefore, if the resource recycling process is performed using surplus electricity, it functions as a receptacle for surplus electricity from renewable energy, etc., while the power generation method and power plant 10 of the embodiment can be said to be power generation with inertia that can balance supply and demand in accordance with the demand and supply of electricity. In other words, by performing the resource recycling process using electricity without inertia, such as renewable energy, it can be said to be a power generation method that can convert the electricity without inertia into electricity with inertia.

[0119] Although an embodiment of the present invention has been described above, the specific configuration aspects of the present invention are not limited to the above embodiment, and the present invention also includes forms in which the above embodiment has been modified or changed within the scope of the gist of the present invention.

[0120] For example, in the above embodiment, the power plant 10 is installed alongside a coal gasification power generation facility (specifically, the integrated coal gasification combined cycle power generation facility 100 and the integrated coal gasification fuel cell combined cycle power generation facility 120), but the power generation facility according to the present invention is not limited to being installed alongside a coal gasification power generation facility. The power generation facility according to the present invention may also be installed alongside, for example, a coal gasification gas storage facility.

[0121] In the above embodiment, the power generation boiler using the powder combustion burner 31 is used as an example. However, there is a type of coal-fired power generation called a stoker boiler, which does not use a pulverized coal burner, and the combustion chamber of the power generation boiler is simply configured like a combustion furnace, and coal is fed in so that combustion continues at all times. The fuel described above may be used in such a configuration. In this case, atomization, which was necessary to maintain combustion as a burner flame, is not necessary, and fuel may be supplied to maintain the heat, so a relatively large size of fuel is sufficient. Furthermore, since magnesium does not fall under the category of dangerous goods under the Fire Service Act if the particle size is about 500 μm, it may be a power generation method using magnesium as fuel by only appropriately crushing the magnesium to a size of 500 μm or more and not performing the hydrogenation process. In other words, when magnesium with a particle size of about 500 μm is supplied to a stoker boiler to carry out the power generation method according to the present invention, the resource regeneration process may be performed up to the coarse crushing process, and the fine crushing process and the hydrogenation process may not be performed.

[0122] In the above embodiment, magnesium is supplied as the inorganic solid fuel to the powder combustion burner 31, but the inorganic solid fuel to be supplied to the powder combustion burner 31 in the present invention is not limited to magnesium, and may be lithium (Li), boron (B), or aluminum (Al). A plurality of substances may be supplied to the powder combustion burner 31 as the inorganic solid fuel. Like magnesium in the above embodiment, lithium is converted into a chloride in a chlorination process, and then electrolyzed and reduced in a molten salt electric field process. Aluminum is not converted into a chloride in a chlorination process, and is electrolyzed and reduced in a molten salt electric field process.

[0123] In addition, in the above embodiment, the coal gasification gas (including gas obtained by subjecting the coal gasification gas produced in the coal gasification plant 101 to a specified treatment, and containing carbon monoxide and carbon dioxide as components) generated in the system of the coal gasification power generation plant (specifically, the integrated coal gasification combined cycle plant 100, the integrated coal gasification fuel cell combined cycle plant 120) is supplied as the combustion supporting gas supplied to the powder combustion burner 31. However, in the present invention, the combustion supporting gas supplied to the powder combustion burner 31 is not limited to the coal gasification gas generated in the system of the coal gasification power generation plant, and may be coal gasification gas generated in another system or stored or preserved independently.

[0124] Furthermore, in the above embodiment, the oxide of magnesium (specifically, magnesium oxide), which is a combustion product produced by combustion in the combustion chamber 21, is reduced by electrolysis, but the method of reduction in the present invention is not limited to electrolysis, and reduction may be performed by other methods. [Explanation of symbols]

[0125] 10. Power Plant 1. Generator 2. Power generation boilers 21 Combustion chamber 22 Steam turbine 23 Piping 24 Water Pump 3. Fuel Storage 31 Powder combustion burner 4. Auxiliary Fuel Storage 41 Auxiliary combustion burner 5 Denitration equipment 6 Dust collector 7. Ash Storage 8. Exhaust pipe 81 Ventilation device 9. Condenser 100 Coal gasification combined cycle power plant 101 Coal gasification facility 102 Gas purification equipment 103 Combustor 104 Gas Turbine 105 Generator 106 Waste heat recovery boiler 107 Steam Turbine 108 Generator 109 Recovery Device 110 Compressor 120 Coal gasification fuel cell combined cycle power plant 121 Shift reaction facility 122 Separation equipment 123 Compressor 124 Fuel Cell 125 Fuel Cell Post-Combustor 300 Apparatus for carrying out the hydrogenation process 310 Heating container 311 Entrance 312 Heating section 313 Vessel Department 314 Valve 315 Piping 320 Heater

Claims

1. In the combustion chamber of the power generation boiler, inorganic solid fuel and coal gasification gas as a combustion supporting gas are combusted. Power generation method.

2. The inorganic solid fuel is at least one of lithium, magnesium, boron, and aluminum; The method for generating electricity according to claim 1 .

3. the inorganic solid fuel is at least one of lithium, magnesium, and aluminum; The oxides, which are the combustion products of the inorganic solid fuel, are subjected to a reduction treatment and are repeatedly used as the inorganic solid fuel. The method for generating electricity according to claim 1 .

4. The inorganic solid fuel is at least one of at least partially hydrogenated lithium, magnesium, boron, and aluminum; The method for generating electricity according to claim 1 .

5. The inorganic solid fuel is at least one of at least partially hydrogenated lithium, magnesium, and aluminum; The oxides, which are the combustion products of the inorganic solid fuel, are subjected to a reduction treatment and a hydrogenation treatment, and are repeatedly used as the inorganic solid fuel. The method for generating electricity according to claim 1 .

6. The combustion supporting gas is a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility. The method for generating electricity according to claim 1 .

7. The combustion supporting gas is a fuel gas obtained by refining a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility in a gas refining facility. The method for generating electricity according to claim 1 .

8. The combustion supporting gas is an exhaust gas discharged by combusting a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility, the fuel gas being refined in a gas refining facility, and the fuel gas being combusted in a combustor. The method for generating electricity according to claim 1 .

9. The combustion supporting gas is a dry gas obtained by purifying a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility in a gas purification facility to produce a fuel gas, and combusting the fuel gas in a combustor to produce an exhaust gas from which moisture has been separated. The method for generating electricity according to claim 1 .

10. The combustion supporting gas is a shift gas obtained by purifying a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility in a gas purification facility to obtain a fuel gas, and then subjecting the fuel gas to a water-gas shift reaction. The method for generating electricity according to claim 1 .

11. the combustion supporting gas is carbon dioxide gas obtained by purifying a coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility in a gas purification facility to produce a fuel gas, and subjecting the fuel gas to a water-gas shift reaction to produce a shift gas from which hydrogen has been separated; The method for generating electricity according to claim 1 .

12. The amount of the combustion supporting gas supplied to the combustion chamber is adjusted to maintain the pressure in the combustion chamber at a predetermined pressure. The method for generating electricity according to claim 1 .

13. In a combustion chamber of a power generation boiler, inorganic solid fuel and coal gasification gas serving as a combustion supporting gas are combusted, The amount of the combustion supporting gas supplied to the combustion chamber is adjusted to maintain the pressure in the combustion chamber at a predetermined pressure. Power generation equipment.

Images