JP2024016750A - Power generation method and power generation equipment - Google Patents

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

The present invention relates to a power generation method and power generation equipment.

A coal-fired power generation system including a power generation boiler is generally known (see, for example, Non-Patent Document 1).

However, even though Japan possesses one of the world's leading coal-fired power generation technologies, the problem of coal emitting carbon dioxide when it is burned means that opportunities for utilizing this technology are being lost.

As a technology to solve these problems, so-called CCS (carbon dioxide capture and storage) efforts are underway to separate and recover carbon dioxide from the exhaust gas of thermal power plants and store the recovered carbon dioxide. It is being said.

For example, Non-Patent Document 2 introduces an initiative in Tomakomai City, Hokkaido regarding CCS. It is explained that the water is injected and stored deep underground under the seabed about 3 to 4 km from the coast. It is thought that the carbon dioxide injected deep into the earth in this way is stably stored over a long period of time, and over many years it dissolves in salt water and becomes minerals in the crevices of rocks.

However, in order to carry out this type of storage, there are many constraints such as the geological strata having gaps that can store carbon dioxide and being covered with a stratum that does not allow carbon dioxide to pass through. .

“Promoting regional environmental conservation: Mechanism of coal-fired power plants and various environmental conservation measures”, [online], Okinawa Electric Power Co., Inc., [searched on June 30, 2020], Internet <URL: https://www .okiden.co.jp/environment/report2017/sec6/sec63.html＞ “CCS, which captures and buries CO2, is finally coming to fruition after demonstration tests (Part 1)”, [online], November 27, 2020, Agency for Natural Resources and Energy, Ministry of Economy, Trade and Industry, [June 2020] Searched on the 16th of the month], Internet <URL: https://www.enecho.meti.go.jp/about/special/johoteikyo/ccs_tomakomai.html>

The present invention has been made in view of these circumstances, and aims to provide a power generation method and power generation equipment that suppress carbon dioxide emissions by utilizing technology cultivated in coal-fired power generation.

MEANS TO SOLVE THE PROBLEM In order to achieve the said objective, this invention is understood by the following structure.
(1) The power generation method of the present invention combusts an inorganic solid fuel and coal gasification gas as a combustion assisting gas in a combustion chamber of a power generation boiler.

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

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

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

(5) In the configuration of (1) above, the inorganic solid fuel is at least one of at least partially hydrogenated lithium, magnesium, and aluminum, and is a combustion product of the inorganic solid fuel. The oxide is subjected to reduction treatment and hydrogenation treatment, and is repeatedly used as the inorganic solid fuel.

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

(7) In the configuration of (1) above, the combustion auxiliary gas is a fuel gas obtained by refining coal gasification gas produced in a coal gasification facility of a coal gasification power generation facility using a gas purification facility.

(8) In the configuration of (1) above, the combustion assisting gas is a fuel gas produced by refining coal gasification gas produced in a coal gasification equipment of a coal gasification power generation equipment in a gas purification equipment, and the fuel gas is This is the exhaust gas that is emitted from combustion in a combustor.

(9) In the configuration of (1) above, the combustion assisting gas is produced by refining coal gasification gas produced in a coal gasification equipment of a coal gasification power generation equipment in a gas purification equipment to produce a fuel gas; This is dry gas after moisture has been separated from the exhaust gas discharged from combustion in a combustor.

(10) In the configuration of (1) above, the combustion assisting gas is a fuel gas produced by refining coal gasification gas produced in a coal gasification equipment of a coal gasification power generation equipment in a gas purification equipment, and the fuel gas is This is a shift gas obtained by a water gas shift reaction.

(11) In the configuration of (1) above, the combustion auxiliary gas is produced by refining coal gasification gas produced in a coal gasification equipment of a coal gasification power generation equipment in a gas purification equipment to produce a fuel gas; This is carbon dioxide gas after hydrogen has been separated from the shift gas obtained by subjecting it to a water gas shift reaction.

(12) The power generation equipment of the present invention combusts an inorganic solid fuel and coal gasification gas as a combustion assisting gas in a combustion chamber of a power generation boiler, and maintains the pressure in the combustion chamber at a predetermined pressure. Therefore, the amount of the auxiliary combustion gas supplied to the combustion chamber is adjusted.

According to the present invention, it is possible to provide a power generation method and power generation equipment that suppress carbon dioxide emissions by utilizing technology cultivated in coal-fired power generation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system diagram for explaining the schematic configuration of a coal gasification combined cycle facility in an embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is a system diagram for demonstrating the schematic structure of the coal gasification fuel cell combined power generation facility in embodiment. 1 is a diagram for explaining a schematic configuration of a power plant for performing a power generation process according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for demonstrating the schematic structure of the apparatus for carrying out the hydrogenation process of embodiment based on this invention.

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.

The power generation equipment according to the present invention may be installed, for example, in a coal gasification combined cycle facility (IGCC) or in a coal gasification fuel cell combined cycle facility (IGFC). First, a coal gasification combined power generation facility and a coal gasification fuel cell combined power generation facility in which the power generation facility according to the present invention can be installed will be described. Coal gasification combined power generation equipment and coal gasification fuel cell combined power generation equipment are also referred to as "coal gasification power generation equipment."

(Coal gasification combined cycle facility (IGCC))
FIG. 1 is a system diagram for explaining the schematic configuration of a coal gasification combined cycle power generation facility 100 in an embodiment.

The coal gasification integrated power generation facility 100 burns the coal gasified gas produced in the coal gasification facility 101 in a combustor 103 to drive a gas turbine 104 to obtain electric power, and also recovers the exhaust heat of the gas turbine 104. This is a power generation facility that generates electric power by driving a steam turbine 107 using the steam generated. Since the coal gasification combined cycle power generation facility 100 is a well-known mechanism, a detailed explanation will be omitted, but the general configuration (particularly the configuration related to the present invention) is as follows.

The coal gasification equipment 101 includes a coal gasification furnace, is supplied with coal and an oxidizing agent, and produces coal gasification gas by gasifying the coal through a reaction of the oxidizing agent. The oxidizing agent supplied to the coal gasifier of the coal gasification equipment 101 is an oxygen (O ₂ )-containing gas, and the main component may be oxygen, oxygen and nitrogen (N ₂ ), Air may also be used. Coal gasification gas contains carbon monoxide (CO) and hydrogen (H ₂ ) as main components.

The coal gasification equipment 101 includes a dust remover and a heat exchanger, and performs dust removal processing on the coal gasification gas generated in the coal gasification furnace and adjusts the coal gasification gas to a predetermined temperature. . Coal gasification gas produced by coal gasification equipment 101 is sent to gas purification equipment 102 .

Coal gasification gas contains impurities, sulfur, and the like in addition to combustible components such as carbon monoxide (CO) and hydrogen (H ₂ ). The gas purification equipment 102 refines the coal gasification gas supplied from the coal gasification equipment 101 by removing impurities, sulfur, and the like contained therein.

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

The combustor 103 combusts fuel gas (CO, H ₂ ) 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 (O ₂ ) is supplied to the combustor 103 as an oxidizing agent. High-temperature, high-pressure combustion gas discharged from the combustor 103 is sent to a gas turbine 104. The combustion gas contains carbon dioxide (CO ₂ ) and moisture (H ₂ O).

The gas turbine 104 rotates the turbine by expanding high-temperature, high-pressure combustion gas supplied from the combustor 103, thereby driving the generator 105.

The exhaust heat recovery boiler 106 recovers heat from exhaust gas discharged from the gas turbine 104 to generate steam. The exhaust gas whose heat has been recovered by the exhaust heat recovery boiler 106 is sent to the compressor 110.

The steam turbine 107 uses steam generated by the exhaust heat recovery boiler 106 to rotate the turbine and drive the generator 108 .

The recovery device 109 separates moisture (H ₂ O) among the components of the exhaust gas from at least a portion of the exhaust gas (CO ₂ , H ₂ O) discharged from the exhaust heat recovery boiler 106 and converts it into carbon dioxide ( CO ₂ ) is recovered. The recovery device 109 separates (in other words, removes) moisture from the exhaust gas, for example, by drying the exhaust gas. The exhaust gas (CO ₂ ) after moisture has been separated/removed is referred to as "dry gas".

The compressor 110 receives exhaust gas discharged from the exhaust heat recovery boiler 106 , compresses the exhaust gas, and supplies the compressed gas to the combustor 103 . At this time, excess carbon dioxide from the exhaust gas discharged from the exhaust heat recovery boiler 106 is recovered by the recovery device 109.

(Coal gasification fuel cell combined power generation facility (IGFC))
FIG. 2 is a system diagram for explaining the schematic configuration of the coal gasification fuel cell combined power generation facility 120 in the embodiment.

The coal gasification fuel cell combined power generation equipment 120 uses the coal gasification gas produced in the coal gasification equipment 101 as an anode (fuel) supplied to the anode electrode (fuel electrode; not shown) of the fuel cell 124. , an oxidizing agent is supplied to the cathode (air electrode, oxygen electrode; not shown) of the fuel cell 124 to generate electricity through an electrochemical reaction, and at the same time, the exhaust gas discharged from the fuel cell 124 drives the gas turbine 104. This is a power generation facility that generates electric power by collecting exhaust heat from the gas turbine 104 and driving a steam turbine 107 using steam generated by recovering exhaust heat from the gas turbine 104. Since the coal gasification fuel cell combined power generation facility 120 is a well-known mechanism, a detailed explanation will be omitted, but the general configuration (particularly the configuration related to the present invention) is as follows. Further, regarding the coal gasification fuel cell combined power generation facility 120, the same components as those of the above-mentioned coal gasification combined power generation facility 100 are given the same reference numerals, and the description thereof will be omitted as appropriate.

The shift reaction equipment 121 converts carbon monoxide and water (specifically, for example, steam ) to generate hydrogen and carbon dioxide. Specifically, the shift reaction equipment 121 utilizes a water gas shift reaction (see reaction formula 1 below) to react carbon monoxide (CO) and water (H ₂ O) to produce hydrogen (H ₂ ). and carbon dioxide (CO ₂ ).
CO + H ₂ O → H ₂ + CO ₂ (1)

The gas after the water gas shift reaction (CO ₂ , H ₂ ; referred to as “shift gas”) generated by the shift reaction equipment 121 is sent to the separation equipment 122.

The separation equipment 122 separates hydrogen (H ₂ ) from among the components of the shift gas (CO ₂ , H ₂ ) supplied from the shift reaction equipment 121 and supplies it to the fuel cell 124 . The gas after hydrogen is separated from the shift gas is carbon dioxide (CO ₂ ) gas.

Compressor 123 compresses air and supplies it to fuel cell 124 .

The fuel cell 124 receives hydrogen from the separation facility 122 and compressed air from the compressor 123 . Hydrogen as a 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, and power is generated by an electrochemical reaction.

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

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

(Resource recycling type power generation equipment)
The power generation method according to the embodiment of the present invention includes a power generation process in which fuel is combusted in the combustion chamber 21 of a power generation boiler 2 to generate power, and raw materials for fuel are generated from combustion ash generated during combustion (in other words, recycled ) a resource recycling process.

(Power generation process)
The power generation process is a process carried out at a power plant, and the technology used there utilizes the technology cultivated in coal-fired power generation (specifically, inorganic solid fuel instead of pulverized coal). (in which the powder of

FIG. 3 is a diagram for explaining the schematic configuration of the power plant 10 for performing the power generation process of the embodiment according to the present invention.

In the power generation method according to the embodiment of the present invention, inorganic solid fuel and coal gasified gas as combustion supporting gas are combusted in the combustion chamber 21 of the power generation boiler 2. The gas is coal gasification gas produced in the coal gasification equipment 101 of the coal gasification power generation equipment.

As shown in FIG. 3, the power plant 10 includes a generator 1, a power generation boiler 2 that drives the generator 1, a fuel storage 3 that stores fuel to be supplied to the power generation boiler 2, and a power generation boiler 2. An auxiliary fuel storage 4 that stores auxiliary fuel to be supplied, a denitrification device 5 that detoxifies (in other words, removes) nitrogen oxides (NOx) contained in exhaust gas discharged from the power generation boiler 2, and a denitrification device 5. It is equipped with a dust collector 6 that collects combustion ash contained in the exhaust gas that has passed through the exhaust gas, and a combustion ash storage 7 that stores the combustion ash.

The power generation boiler 2 includes 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. A piping 23 is provided for supplying water returned to a liquid state by the water dispenser 9 to the combustion chamber 21 again.

A water supply pump 24 is provided in the middle of the pipe 23 connecting the condenser 9 and the combustion chamber 21, and is configured to send water returned to a liquid state by the condenser 9 to the combustion chamber 21 side. ing.

The combustion chamber 21 includes a powder combustion burner 31 that burns powdered fuel supplied from the fuel storage 3 and an auxiliary combustion burner 41 that burns liquid fuel (for example, heavy oil, light oil, etc.) supplied from the auxiliary fuel storage 4. and.

In the present invention, the combustion of the powdered fuel in the combustion chamber 21 is preferably performed in an oxygen-free environment (in other words, in an atmosphere). Even if the atmosphere within the combustion chamber 21 contains oxygen, it is preferable that the oxygen concentration is adjusted to a low enough concentration to allow generation of carbon (C) as a combustion product. That is, the oxygen concentration is adjusted to be so low that the reaction between magnesium and oxygen is not dominant (in other words, it is not prioritized) compared to the reaction between magnesium and the combustion supporting gas (for example, carbon monoxide, carbon dioxide) in the present invention. It is preferable that

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 for supplying powder fuel and combustion supporting gas to the powder combustion burner 31 may also be used in coal-fired power generation. It may be the same as that used in

The auxiliary combustion burner 41 is a burner for obtaining auxiliary thermal power until the temperature in the combustion chamber 21 rises and the combustion of the powder combustion burner 31 becomes stable, and this is also similar to that used in coal-fired power generation. That's fine.

Note that after the combustion of the powder combustion burner 31 becomes stable, the auxiliary thermal power provided by the auxiliary combustion burner 41 is not required. Since thermal power plants basically operate without stopping, the amount of carbon dioxide generated by auxiliary thermal power, which is used only at the start of operation, is at a level that is almost nonexistent.

The fuel storage 3 stores magnesium (Mg) as a powdered fuel that does not emit carbon dioxide during combustion, which is an inorganic solid fuel in the present invention. The magnesium stored in the fuel storage 3 may be magnesium hydride (MgH ₂ ) having at least a hydrogenated layer on its surface, or may be a mixture of magnesium and magnesium hydride.

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

The pulverized coal used in pulverized coal burners used in coal-fired power generation is generally 150 μm or less, and by reducing the particle size of magnesium to 150 μm or less, a burner with the same structure as the pulverized coal burner can be made into powder. It has the advantage that it can be used as a combustion burner 31.

In the powder combustion burner 31, magnesium mixed with combustion supporting gas is combusted.

Carbon monoxide or carbon dioxide generated in the system of the coal gasification combined cycle facility 100 described above may be supplied as the auxiliary gas supplied to the powder combustion burner 31; Carbon monoxide and carbon dioxide generated in the system of the fuel cell combined power generation facility 120 may be supplied.

a) Magnesium (Mg), coal gasification gas (CO, H ₂ ) discharged from the coal gasification equipment 101 of the coal gasification combined power generation equipment 100 and the coal gasification fuel cell combined power generation equipment 120 and the gas purification equipment 102 The combustion reaction (including the generation of heat; the same applies hereinafter) with carbon monoxide (CO) out of the fuel gas (CO, H ₂ ) discharged from the fuel gas (CO, H 2 ) is as shown in reaction formula 2 below. Further, the combustion reaction between magnesium hydride (MgH ₂ ) and carbon monoxide is as shown in Reaction Formula 3 below. Note that magnesium oxide (MgO) and carbon (C) produced by the combustion reaction are solids (specifically, powder).
Mg + CO → MgO + C (2)
MgH ₂ + CO → MgO + H ₂ + C (3)

b) The combustion reaction between magnesium (Mg) and carbon dioxide (CO ₂ ) of the combustion gas (CO ₂ , H ₂ O) discharged from the combustor 103 of the coal gasification combined cycle power generation facility 100 is as follows. As shown in reaction formula 4. Further, the combustion reaction between magnesium hydride (MgH ₂ ) and carbon dioxide is as shown in Reaction Formula 5 below. In addition, the combustion reaction between magnesium and water (H ₂ O) is as shown in Reaction Formula 6 below. Further, the combustion reaction between magnesium hydride (MgH ₂ ) and water is as shown in Reaction Formula 7 below.
2Mg + CO ₂ → 2MgO + C (4)
2MgH ₂ + CO ₂ → 2MgO + 2H ₂ + C (5)
Mg + H ₂ O → MgO + H ₂ (6)
MgH ₂ + H ₂ O → MgO + 2H ₂ (7)

c) The combustion reaction between magnesium (Mg) and carbon dioxide (CO ₂ ) gas (i.e., dry gas) discharged from the recovery device 109 of the coal gasification combined cycle power generation facility 100 is shown in reaction formula 8 below. That's right. Further, the combustion reaction between magnesium hydride (MgH ₂ ) and carbon dioxide is as shown in Reaction Formula 9 below.
2Mg + CO ₂ → 2MgO + C (8)
2MgH ₂ + CO ₂ → 2MgO + 2H ₂ + C (9)

D) The combustion reaction between magnesium (Mg) and carbon dioxide (CO ₂ ) of the shift gas (CO ₂ , H ₂ ) discharged from the shift reaction equipment 121 of the coal gasification fuel cell combined power generation equipment 120 is as follows: This is as shown in Reaction Formula 10 below. Further, the combustion reaction between magnesium hydride (MgH ₂ ) and carbon dioxide is as shown in Reaction Formula 11 below.
2Mg + CO ₂ → 2MgO + C (10)
2MgH ₂ + CO ₂ → 2MgO + 2H ₂ + C (11)

e) Magnesium (Mg) and carbon dioxide (CO 2 ) after hydrogen (H ₂ ) is separated from the shift gas (CO ₂ , H ₂ ) in the separation process in the separation facility 122 of the coal gasification fuel cell combined power generation facility ₁₂₀ ) is as shown in Reaction Formula 12 below. Further, the combustion reaction between magnesium hydride (MgH ₂ ) and carbon dioxide is as shown in Reaction Formula 13 below.
2Mg + CO ₂ → 2MgO + C (12)
2MgH ₂ + CO ₂ → 2MgO + 2H ₂ + C (13)

As described above, magnesium oxide (MgO) and carbon (C) are generated in the combustion reaction in the powder combustion burner 31, and carbon dioxide (CO ₂ ) is not generated during combustion for power generation. However, for example, if the combustion auxiliary gas supplied to the powder combustion burner 31 contains moisture, the water and a portion of the magnesium oxide will react, and magnesium hydroxide (Mg(OH) ₂ ) will be formed in the combustion ash. may be included.

Here, the combustion reaction between magnesium and the combustion assisting gas is a pressure reduction reaction in which a solid is generated by the reaction between solid and gas, and when the inorganic solid fuel and the combustion assisting gas are completely combusted in the combustion chamber 21, the combustion chamber 21 In order to maintain the pressure inside the combustion chamber 21 at a predetermined pressure (for example, about 1 atmosphere, or within the allowable pressure range as the pressure inside the combustion chamber 21), the pressure inside the combustion chamber 21 may decrease. , the amount of combustion-assisting gas supplied to the combustion chamber 21 may be adjusted. In this case, for example, a pressure adjustment system in which gas discharged outside the combustion chamber 21 without contributing to the reaction within the combustion chamber 21 is collected and then reinjected into the combustion chamber 21 is provided. It may be provided separately from the supply system and combustion system associated with the powder combustion burner 31.

As a response to the case where nitrogen oxides (NOx) are generated during combustion within the combustion chamber 21, in order to detoxify (in other words, remove) the nitrogen oxides in the exhaust gas discharged from the combustion chamber 21, A denitrification device 5 is provided in the middle of an exhaust pipe 8 for sending exhaust gas discharged from the combustion chamber 21 to a dust collector 6.

The denitrification device 5 is a denitrification device used in coal-fired power generation that has the function of adding ammonia (NH ₃ ) to exhaust gas and passing it through a catalyst layer to decompose nitrogen oxides into harmless nitrogen and water. Something similar to this is fine.

Although the exhaust gas that has passed through the denitrification device 5 does not contain harmful gases, it does contain combustion ash (specifically, powdered magnesium oxide, magnesium hydroxide, and carbon) generated during combustion. Some of these particles have extremely small particle sizes. For this reason, the exhaust pipe 8 is connected to the dust collector 6, and after the dust collector 6 collects the combustion ash, the exhaust gas is released into the atmosphere.

The dust collector 6 may be similar to a dust collector used in coal-fired power generation, and specifically may be, for example, an electric dust collector.

In the example shown in FIG. 3, an exhaust device 81 is provided downstream of the dust collector 6, so that the exhaust gas in the combustion chamber 21 is discharged into the atmosphere through the denitrification device 5 and the dust collector 6.

On the other hand, since coal-fired power generation uses coal as fuel, the sulfur component contained in the coal is included in the exhaust gas. For this reason, in coal-fired power generation, a desulfurization device is further provided before exhaust gas is released into the atmosphere. On the other hand, in the present invention, since magnesium does not contain a sulfur component, there is an advantage that a desulfurization device is not required.

In addition, in coal-fired power generation, the exhaust gas contains carbon dioxide, so it is necessary to release the exhaust gas into the atmosphere from a tall chimney. In contrast, the present invention does not require such a tall chimney.

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 subjected to the resource regeneration process described below for resource circulation. After that, it is repeatedly regenerated into magnesium. The regenerated magnesium is used as an inorganic solid fuel supplied to the powder combustion burner 31.

In addition, even in coal-fired power generation, dust collectors are used because coal residue accumulates at the bottom of the combustion chamber and is also included in the exhaust gas, and a mechanism for collecting magnesium combustion ash is also used. A mechanism similar to that used in coal-fired power generation may be used.

As can be seen from the above explanation, if magnesium with a particle size of 150 μm or less is used as fuel, it will be compatible with the coal-fired power generation technology that has been cultivated up to now, which generates electricity by burning pulverized coal in a pulverized coal burner. A highly compatible power generation process with reduced carbon dioxide emissions can be performed.

(Resource recycling process)
Next, we will explain the resource recovery process of producing magnesium again using magnesium oxide (specifically, magnesium oxide) contained in combustion ash as a combustion product generated in the power generation process as a starting material. .

Regarding magnesium hydroxide (Mg(OH) ₂ ) contained in the combustion ash, when heated, a dehydration reaction occurs as shown in reaction formula 14 below and it becomes magnesium oxide (MgO), so it is difficult to start the resource recovery process. The material can be considered to be magnesium oxide.
Mg(OH) ₂ → MgO + H ₂ O (14)

The procedure for producing magnesium from the starting material magnesium oxide is a chlorination process that produces magnesium chloride using magnesium oxide, which is combustion ash, and a melting process that produces magnesium using magnesium chloride produced in the chlorination process. It can be divided into salt electrolysis process.

(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 to be used in the subsequent molten salt electrolysis process.

In the chlorination step, first, powdered magnesium oxide (MgO) and carbon (C), which are combustion ash, are introduced into hydrogen chloride (HCl) water. Magnesium oxide undergoes the following reaction formula 15 in hydrogen chloride water to become magnesium chloride (MgCl ₂ ). Magnesium chloride produced by the reaction is a substance with high solubility in water, so it will dissolve in hydrogen chloride water if the water content is sufficiently large.
MgO + 2HCl → MgCl ₂ + H ₂ O (15)

On the other hand, carbon does not cause a reaction and does not dissolve, so it remains in the hydrogen chloride water in powder form. Therefore, carbon in the combustion ash is recovered by filtering hydrogen chloride water in which magnesium chloride is dissolved.

The carbon recovered by the above method has high purity and is useful as an industrial material, and is particularly useful in fields where carbon materials with high purity are required.

Anhydrous magnesium chloride is recovered from the hydrogen chloride water after filtering the carbon. An example of a method for recovering anhydrous magnesium chloride from aqueous hydrogen chloride is a method of heating while blowing hydrogen chloride gas into the aqueous hydrogen chloride. Since this method is a well-known procedure, detailed explanation will be omitted.

As a method for recovering anhydrous magnesium chloride from hydrogen chloride water, or by heating hydrogen chloride water (magnesium chloride is dissolved in the state of hexahydrate) in a nitrogen atmosphere to eliminate water. Anhydrous magnesium chloride may be obtained, or hydrogen chloride may be eliminated to obtain magnesium oxide, and the magnesium oxide may be further processed.

In the above case, magnesium oxide may be converted into magnesium chloride by causing a reaction of reaction formula 16 below with magnesium oxide and hydrogen chloride gas at a temperature of about 300 to 600°C.
MgO + 2HCl → MgCl ₂ + H ₂ O (16)

In the above case, magnesium oxide can be converted into magnesium chloride by causing the reaction of reaction formula 17 below with magnesium oxide and ammonium chloride (NH ₄ Cl) at a temperature of about 300 to 600°C. You can also do this.
MgO + 2NH ₄ Cl → MgCl ₂ + H ₂ O + 2NH ₃ (17)

In the above case, for magnesium oxide, or by causing the reaction of reaction formula 18 below at a temperature of about 400°C with a molar ratio of magnesium oxide and ammonium chloride of 1:3, ammonium carnalite can be hydrated. After producing the product, ammonium carnalite hydrate is heated under a stream of ammonia gas to a temperature slightly lower than the sublimation temperature of ammonium chloride (for example, about 5 to 20 degrees Celsius lower than the sublimation temperature). Moisture is removed by causing the dehydration reaction of reaction formula 19 below, and then heated to a temperature higher than the sublimation temperature of ammonium chloride (for example, around 400°C) under a stream of dry nitrogen to produce the following reaction formula. Anhydrous magnesium chloride may be obtained by removing the ammonium chloride moiety by causing the reaction in step 20.
MgO+ _3NH4Cl → _MgCl2・_NH4Cl・_H2O + _2NH3 (18)
_MgCl2・_NH4Cl・_H2O → _MgCl2・_NH4Cl + _H2O (19)
MgCl ₂ .NH ₄ Cl → MgCl ₂ +NH ₃ +HCl (20)

(Molted salt electrolysis process)
The molten salt electrolysis process is a process of producing magnesium by electrolysis using anhydrous magnesium chloride produced in the chlorination process as a material, and is one method used for producing magnesium.

The outline of the molten salt electrolysis process is, for example, heating magnesium chloride to a temperature of around 700° C. in a brick furnace to melt the magnesium chloride.

A brick furnace is equipped with at least one pair of electrodes, and when a power source is connected between these electrodes and a voltage of 2.5V or higher is applied, chlorine (Cl ₂ ) gas is generated at the anode, and magnesium gas is generated at the cathode. is generated.

Hydrogen chloride gas is produced by reacting hydrogen gas and chlorine gas, so even if hydrogen chloride gas is generated from chlorine gas generated in the molten salt electrolysis process and used in the chlorination process. good.

(Atomization process)
The atomization process is a process of turning the magnesium produced in the molten salt electrolysis process into powdered magnesium, and may be performed using a general pulverizer, or a fine powder manufacturing device called a gas atomizer. may be used.

When a pulverizing device is used to carry out the atomization process, it is preferable to carry out the pulverization process in two stages in consideration of pulverization efficiency.

Specifically, the atomization process includes a coarse pulverization process in which the particle size is approximately 180 to 800 μm using a device with a high pulverization speed, although the pulverization process does not result in fine granulation, and a coarse pulverization process in which the magnesium pulverized in the coarse pulverization process is pulverized to a particle size of 150 μm or less. It is preferable to carry out the process in two stages: a fine pulverization step in which the particles are pulverized to a particle size of .

The particle size in the atomization process does not mean an accurate spherical shape, but the particle size in the coarse pulverization process is, for example, a particle size that can pass through a sieve with a mesh opening of about 0.8 mm. be.

When grinding magnesium coarsely, the fact that magnesium is a soft metal does not cause any harm, but when grinding it finely, the problem is that magnesium sticks together during the grinding process, making it difficult to form a fine powder. may occur. For this reason, in the pulverization step, it is preferable that a pulverization aid be added to the coarsely pulverized magnesium.

As the grinding aid, for example, stearic acid can be used, but it is preferable to use powder of an inorganic compound. Specifically, for example, by using magnesium oxide, which is an inorganic compound powder, as a grinding aid, it is possible to divert a portion of the combustion ash as a grinding aid because it has the same composition as combustion ash. It becomes possible.

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

Here, when magnesium comes into contact with oxygen after being atomized, an oxide film is formed on the surface, significantly reducing reaction efficiency. For this reason, the magnesium pulverized in the pulverization step is handled so as not to come into contact with oxygen until the hydrogenation step is completed.

A method for carrying out the hydrogenation process without exposure to outside air will be described with reference to FIG. 4, which is a diagram illustrating the configuration of an apparatus for carrying out the hydrogenation process.

As shown in FIG. 4, an apparatus 300 for carrying out the hydrogenation process includes a heating container 310 that accommodates atomized magnesium and reacts with hydrogen, a heater 320 that heats the heating container 310, and A pipe 315 is detachably connected to an inlet 311 of the container 310.

The heating container 310 is provided with a valve 314 in a pipe section 313 extending from an inlet 311 to a heating section 312, and has a sealed structure when the valve 314 is closed.

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

The heating container 310 also serves as a recovery container for recovering the magnesium pulverized in the pulverization process.

As described above, the pulverization process is performed under an argon gas atmosphere, and the valve 314 is closed and removed before the heating container 310 is removed from the pulverizer that performs the pulverization process, so that the pulverization process is carried out in the heating container 310. The magnesium thus obtained is connected to an apparatus 300 shown in FIG. 4 under argon.

Then, before the valve 314 is opened, evacuation is performed, and after the piping 315 and the air on the previous stage side than the valve 314 are exhausted, the valve 314 is opened, and the argon gas in the heating section 312 is exhausted.

After that, the heater 320 is driven to heat the temperature inside the heating unit 312 to a temperature suitable for hydrogenation (specifically, 180° C. to 220° C.), and hydrogen gas is supplied to the heating container 310, Hydrogenation treatment (see reaction formula 21 below) is performed.
Mg + H ₂ → MgH ₂ (21)

Here, magnesium hydride with a hydrogenation rate of about 20% by mass has almost the same calorific value per weight as coal, so as a fuel to replace coal (in other words, in place of coal), low-purity hydrogen Magnesium is fine. Furthermore, when magnesium becomes a fine powder, it becomes easily combustible and is generally treated as a dangerous substance under the Fire Service Act. On the other hand, magnesium hydride is less flammable due to hydrogenation, and even in fine powder form it is not classified as a dangerous substance under the Fire Service Act. Therefore, hydrogenation of magnesium only needs to achieve a hydrogenation rate that does not fall under the category of hazardous materials in terms of transportation, storage, etc.

Note that the hydrogenation of magnesium does not proceed in proportion to the treatment time, but the rate of progress slows down significantly as the purity increases. Therefore, by using low-purity magnesium hydride with a hydrogenation rate of 30% by mass or less (for example, about 20% by mass) that is hydrogenated at least on the surface side, the time required for the hydrogenation process can be significantly reduced. This makes it possible to significantly increase productivity.

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

Note that as the inorganic solid fuel in the present invention, magnesium hydride with a high hydrogenation rate may be used, or a mixture of magnesium and magnesium hydride may be used.

(effect)
According to the power generation method and power plant 10 according to the embodiment, in the combustion chamber 21 of the power generation boiler 2, inorganic solid fuel (specifically, magnesium, magnesium hydride) and coal gasification as a combustion supporting gas are used. Since gas is burned, carbon dioxide is not generated during power generation, and furthermore, it is possible to realize resource recycling type thermal power generation in which magnesium resources are recycled. Furthermore, according to the power generation method and power plant 10 according to the embodiment, carbon dioxide emitted from coal gasification power generation equipment (specifically, coal gasification combined power generation equipment, coal gasification fuel cell combined power generation equipment) By using it as a combustion auxiliary gas to generate electricity, it is possible to significantly reduce the environmental impact of coal-fired power generation.

According to the power generation method and power plant 10 according to the embodiment, it is possible to use a mechanism similar to that used in coal-fired power generation, so that the technology cultivated in coal-fired power generation can be used to reduce carbon dioxide. This makes it possible to suppress emissions.

According to the power generation method and power plant 10 according to the embodiment, since the resource regeneration process consists only of equipment that runs on electric power, it is possible to regenerate fuel using only surplus electric power that cannot be connected to the grid. becomes. Therefore, if the resource regeneration process is carried out using surplus power, it will function as a receiver for surplus power such as renewable energy, while the power generation method and power plant 10 according to the embodiment will meet the demand for power. It can be said that it is a power generation with inertial force that can balance supply and demand according to supply and demand. In other words, it can be said that this is a power generation method that can convert the power without inertia into power with inertia by performing the resource regeneration process using power without inertia such as renewable energy.

Although the embodiments of the present invention have been described above, the specific configuration aspects of the present invention are not limited to the above embodiments, and modifications and variations may be made to the above embodiments without departing from the gist of the present invention. The present invention also includes forms in which changes and the like are added.

For example, in the above embodiment, a case where the power plant 10 is installed alongside a coal gasification power generation facility (specifically, a coal gasification combined power generation facility 100 and a coal gasification fuel cell combined power generation facility 120) is taken as an example. Although described above, the power generation equipment according to the present invention is not limited to an aspect in which it is installed alongside a coal gasification power generation equipment. The power generation facility according to the present invention may be installed, for example, in conjunction with a coal gasification gas storage facility.

In addition, in the above embodiment, a power generation boiler using a powder combustion burner 31 was explained as an example, but for coal-fired power generation, the combustion chamber of a power generation boiler without using a pulverized coal burner is called a stoker boiler. There is also a combustion furnace-like configuration in which coal is simply fed so that combustion continues, and the above-described fuel may be used in such a configuration. In this case, there is no need for atomization, which was necessary to sustain combustion as a burner flame, and it is only necessary to supply fuel to maintain thermal power, so a relatively large size of fuel is sufficient. Even magnesium is not classified as a dangerous substance under the Fire Service Act if it has a particle size of about 500 μm, so only appropriate coarse pulverization is performed to keep the size of the magnesium to 500 μm or more, and then the hydrogenation process is carried out. It is also possible to generate electricity using magnesium as fuel. In other words, when implementing the power generation method according to the present invention by supplying magnesium with a particle size of about 500 μm to a stoker boiler, the resource regeneration process is performed up to coarse pulverization, and the fine pulverization process and hydrogenation process are not performed. You may choose not to have one.

Further, in the above embodiment, magnesium is supplied as the inorganic solid fuel supplied to the powder combustion burner 31, but in the present invention, the inorganic solid fuel supplied to the powder combustion burner 31 is magnesium. The material is not limited, and may be lithium (Li), boron (B), or aluminum (Al). Alternatively, a plurality of substances may be supplied to the powder combustion burner 31 as inorganic solid fuels. Note that, like magnesium in the above embodiment, lithium is converted into a chloride through a chlorination process, and then electrolyzed and reduced through a molten salt electric field process. Aluminum is electrolyzed and reduced by the molten salt electric field process without being converted into chloride by the chlorination process.

Furthermore, in the above embodiment, the auxiliary gas supplied to the powder combustion burner 31 is used in coal gasification power generation equipment (specifically, coal gasification combined power generation equipment 100, coal gasification fuel cell combined power generation equipment 120). The coal gasification gas generated in the system (containing gas obtained by subjecting the coal gasification gas produced in the coal gasification equipment 101 to predetermined processing, and containing carbon monoxide and carbon dioxide as components) is supplied. However, in the present invention, the combustion supporting gas supplied to the powder combustion burner 31 is not limited to coal gasification gas generated in the system of coal gasification power generation equipment, but may be generated in other systems or independently. It may be coal gasification gas that is stored or stored.

Further, in the above embodiment, the magnesium oxide (specifically, magnesium oxide), which is a combustion product resulting from combustion in the combustion chamber 21, is reduced by electrolysis. The method is not limited to electrolysis, and the reduction process may be performed by other methods.

10 Power plant 1 Generator 2 Power generation boiler 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 device 6 Dust collector 7 Combustion ash storage 8 Exhaust pipe 81 Exhaust device 9 Condenser 100 Combined coal gasification combined power generation facility 101 Coal gasification facility 102 Gas purification facility 103 Combustor 104 Gas turbine 105 Generator 106 Exhaust heat recovery boiler 107 Steam turbine 108 Generator 109 Recovery device 110 Compressor 120 Coal gasification fuel cell combined power generation equipment 121 Shift reaction equipment 122 Separation equipment 123 Compressor 124 Fuel cell 125 Fuel cell post-stage combustor 300 Device for carrying out the hydrogenation process 310 Heating container 311 Inlet 312 Heating section 313 Pipe section 314 Valve 315 Piping 320 Heater

Claims (12)

Burning inorganic solid fuel and coal gasification gas as combustion supporting gas in the combustion chamber of a power generation boiler,
A power generation method characterized by: the inorganic solid fuel is at least one of lithium, magnesium, boron, and aluminum;
The power generation method according to claim 1, characterized in that: The inorganic solid fuel is at least one of lithium, magnesium, and aluminum,
reducing the oxide that is a combustion product of the inorganic solid fuel and repeatedly using it as the inorganic solid fuel;
The power generation method according to claim 1, characterized in that: The inorganic solid fuel is at least one of at least partially hydrogenated lithium, magnesium, boron, and aluminum.
The power generation method according to claim 1, characterized in that: The inorganic solid fuel is at least one of at least partially hydrogenated lithium, magnesium, and aluminum,
The oxide that is a combustion product of the inorganic solid fuel is subjected to reduction treatment and hydrogenation treatment, and is repeatedly used as the inorganic solid fuel.
The power generation method according to claim 1, characterized in that: The combustion auxiliary gas is coal gasification gas produced in coal gasification equipment of coal gasification power generation equipment,
The power generation method according to claim 1, characterized in that: The combustion assisting gas is a fuel gas obtained by refining coal gasification gas produced in a coal gasification equipment of a coal gasification power generation equipment with a gas purification equipment,
The power generation method according to claim 1, characterized in that: The combustion auxiliary gas is an exhaust gas that is produced by refining 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 be discharged. is,
The power generation method according to claim 1, characterized in that: The combustion auxiliary gas is an exhaust gas that is produced by refining 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 be discharged. is the dry gas after moisture has been separated from
The power generation method according to claim 1, characterized in that: The combustion auxiliary gas is a shift gas obtained by refining coal gasified gas produced in a coal gasification facility of a coal gasification power generation facility using a gas purification facility to obtain a fuel gas, and subjecting the fuel gas to a water gas shift reaction. ,
The power generation method according to claim 1, characterized in that: The combustion auxiliary gas is produced by refining coal gasified gas produced in the coal gasification equipment of the coal gasification power generation equipment in a gas purification equipment to produce a fuel gas, and then producing hydrogen from the shift gas obtained by subjecting the fuel gas to a water gas shift reaction. is the carbon dioxide gas after it is separated,
The power generation method according to claim 1, characterized in that: In the combustion chamber of a power generation boiler, inorganic solid fuel and coal gasification gas as combustion supporting gas are combusted,
In order to maintain the pressure within the combustion chamber at a predetermined pressure, the amount of the combustion assisting gas supplied to the combustion chamber is adjusted.
A power generation facility characterized by: