Power generation method or hydrogen production method and energy conversion system

Abstract

Provided are a power generation method or a hydrogen production method and an energy conversion system, the power generation method or the hydrogen production method being a method for generating power or producing hydrogen from a carbon source, the method comprising: a chemical conversion step for converting the carbon source into hydrogen in a chemical conversion unit; reducing the intermediate medium while oxidizing the carbon source by reacting a mixture in which the solution containing the intermediate medium and the carbon source are mixed at a temperature at which the chemical # imgabs 0 # of the carbon source exceeds the chemical # imgabs 1 # in the reduced state of the intermediate medium; an electrochemical conversion step in which an anode of a battery structure in an electrochemical conversion unit provided with the battery structure is brought into contact with the intermediate medium reduced in the chemical conversion step, and a cathode of the battery structure is brought into contact with oxygen or air to generate power, or the cathode of the battery structure is brought into contact with water to produce hydrogen; and a recycling step for returning the solution containing the intermediate medium after the electrochemical conversion step to the mixture.

Description

Technical Field

[0001] The present invention relates to a method for generating electricity or a method for producing hydrogen and an energy conversion system. Background Art

[0002] Fossil fuels such as high-quality coal and oil are widely used as carbon sources for conversion into electricity in power plants, etc., because they can easily extract large amounts of energy by burning. However, in recent years, the problem of resource depletion has arisen.

[0003] On the other hand, as an alternative energy source to fossil fuels, Hydrogen energy with a high exergy rate has attracted much attention.

[0004] A method for generating electricity or An energy conversion system or energy conversion method with high energy conversion efficiency of resources in the production of high-efficiency (secondary) energy.

[0005] For example, there is known a system or method for utilizing waste heat (also referred to as exhaust heat) which is a low-temperature energy source that has not been used in power plants and the like until now (Patent Documents 1 and 2).

[0006] Patent document 1 describes a hydrogen production device utilizing waste heat, which includes a thermoelectric power generation device, a steam generating device, and an electrochemical device, and utilizes waste heat released in the iron-making process as its energy source, the thermoelectric power generation device having a high-temperature side exposed to high temperature and a low-temperature side exposed to low temperature and converting thermal energy into electrical energy, the steam generating device is used to obtain water vapor, and the electrochemical device produces hydrogen from the water vapor obtained by the water vapor generating device through electrolysis using the electrical energy obtained by the thermoelectric power generation device.

[0007] Patent Document 2 describes a method for recovering waste heat, which uses waste heat below 150 degrees Celsius in the endothermic reforming reaction of methanol (CH3OH) to produce carbon dioxide (CO2) and hydrogen (H2). The heat energy of low-efficiency exhaust heat is converted into The combustible substance with a higher rate than that, namely hydrogen (H2), is recovered.

[0008] In addition, there is also known a method of utilizing a low-quality carbon source such as lignite or biomass (see Patent Documents 3 and 4).

[0009] Patent Document 3 describes a method for producing hydrogen by thermochemical decomposition reaction of water and carbon using cerium oxide as a reaction medium.

[0010] Patent document 4 describes a hydrogen production method, which is a method for producing hydrogen from biomass and iron oxide, and includes a reduction step and a first oxidation step, wherein a solid phase containing iron oxide obtained in the first oxidation step is supplied to the reduction step to circulate iron and iron oxide, wherein a mixture of iron oxide particles and biomass is heated to reduce the iron oxide, and wherein the solid phase containing metallic iron and carbon obtained in the reduction step is brought into contact with water vapor at a temperature below 600°C to generate hydrogen.

[0011] In addition, there is a known method for producing hydrogen by electrolyzing water using electrons obtained from alkali metals and metals with low ionization tendency. For example, Patent Document 5 describes a method for producing hydrogen, including: an electrochemical oxidation-reduction step, in which electrons are released from an alkali metal by a battery reaction using an alkali metal as a negative electrode and carbon or a metal with a lower ionization tendency than the alkali metal as a positive electrode, and a fusion of the alkali metal and carbon or metal is generated; a hydrogen generation step, in which water is electrolyzed using the electrons released in the electrochemical oxidation-reduction step to generate hydrogen; and a thermochemical reduction step, in which the fusion is heated to reduce it to an alkali metal and carbon or metal.

[0012] Prior art literature

[0013] Patent Literature

[0014] Patent Document 1: Japanese Patent Application Publication No. 2011-208242

[0015] Patent Document 2: Japanese Patent Laid-Open No. 05-170401

[0016] Patent Document 3: Japanese Patent Application Laid-Open No. 10-251001

[0017] Patent Document 4: Japanese Patent Application Publication No. 2008-137864

[0018] Patent Document 5: Japanese Patent Application Publication No. 2016-121036 Summary of the invention

[0019] Problems to be solved by the invention

[0020] However, the devices or methods described in Patent Documents 1 to 5 are all required to further improve the energy conversion efficiency. In particular, there is no known means to efficiently use low-quality carbon sources with high water content (e.g., lignite, peat, biomass, etc. with high water content) as energy.

[0021] Furthermore, according to the conventional method, waste heat is generally utilized at a high temperature of 600° C. or higher, and it is difficult to utilize low temperature waste heat of 350° C. or lower.

[0022] Furthermore, in the conventional method of utilizing a carbon source, since the carbon source is temporarily converted into thermal energy, there is a problem of low energy conversion efficiency.

[0023] The problem to be solved by the present invention is to provide a method for generating electricity or a method for producing hydrogen and an energy conversion system which have excellent energy conversion efficiency even when using a low-quality carbon source and utilizing low-temperature waste heat.

[0024] Technical means of solving problems

[0025] In the present invention, power generation or hydrogen production is performed by undergoing energy conversion from a carbon source to an intermediate medium based on a solution reaction. As described above, in the present invention, power generation or hydrogen production can be performed from a carbon source without undergoing the form of thermal energy, thereby improving energy conversion efficiency.

[0026] In addition, in the present invention, low-temperature waste heat can be used for adjusting the reaction environment temperature and the like.

[0027] Furthermore, the chemical properties of carbon source and intermediate medium can be effectively utilized. Specifically, it was found that according to the present invention, by combining a chemical conversion unit that performs a redox reaction of a carbon source and an intermediate medium with a unit that performs power generation or By combining the electrochemical conversion part of the secondary energy with high efficiency and selecting the reaction temperature of the chemical conversion part, the chemical in the reduced state of the intermediate medium can be Smaller than the carbon source , thereby solving the above-mentioned problem.

[0028] The configuration of the present invention and preferred configurations of the present invention will be described below as specific means for solving the above-mentioned problems.

[0029] [1] A method for generating electricity or producing hydrogen, which is a method for generating electricity or producing hydrogen from a carbon source, and comprises: a chemical conversion step, in which a mixture of a solution containing an intermediate medium and a carbon source is subjected to a chemical conversion step of the carbon source; Chemical reaction in the reduced state exceeding the intermediate medium react at a temperature of 100 to 200 °C to oxidize the carbon source and reduce the intermediate medium at the same time; an electrochemical conversion step, wherein an anode of the battery structure in an electrochemical conversion unit having a battery structure is brought into contact with a solution containing the intermediate medium reduced in the chemical conversion step, or a substrate on which the intermediate medium reduced in the chemical conversion step is precipitated is used as the anode of the battery structure, and a cathode of the battery structure is brought into contact with oxygen or air to generate electricity, or a cathode of the battery structure is brought into contact with water to produce hydrogen; and a recycling step, wherein the solution containing the intermediate medium after the electrochemical conversion step is returned to the mixture.

[0030] [2] The method for power generation or hydrogen production according to [1], wherein, in the chemical conversion step, the intermediate medium in a reduced state is precipitated on a substrate, and in the electrochemical conversion step, the substrate on which the intermediate medium is precipitated is used as the anode of the battery structure in the electrochemical conversion section.

[0031] [3] The method for power generation or hydrogen production according to [1] or [2], wherein the reaction temperature in the chemical conversion step is 350° C. or less.

[0032] [4] A method for generating electricity or a method for producing hydrogen according to technical solution [1] or [2], wherein the intermediate medium contains at least one element of V, Cr, Mn, Fe, Cu, and Zn.

[0033] [5] The method for power generation or hydrogen production according to [1] or [2], wherein CO 2 generated by the oxidation-reduction reaction in the chemical conversion unit is recovered.

[0034] [6] An energy conversion system comprising: a chemical conversion unit, which reduces an intermediate medium from an oxidized state to a reduced state while oxidizing the carbon source; and an electrochemical conversion unit, which comprises one electrode, another electrode, and a current supply unit connecting the one electrode to the other electrode, wherein the intermediate medium is oxidized from a reduced state to an oxidized state by using the one electrode and the reduced material is reduced by using the other electrode, wherein in the chemical conversion unit, the carbon source is oxidized from a reduced state to an oxidized state by using the one electrode. The chemical state of the intermediate medium exceeds the reduction state The reduction reaction is carried out at a temperature of , and the electrochemical conversion unit outputs at least one of the reduced product of the reduced material and electricity to the outside.

[0035] [7] The energy conversion system according to [6] includes a plurality of the chemical conversion units and at least one of the electrochemical conversion units.

[0036] [8] The energy conversion system according to [6] includes a plurality of the electrochemical conversion units, a portion of the electrochemical conversion units outputs hydrogen as the reduced material to the outside, and another portion of the electrochemical conversion units outputs electricity to the outside, and the electricity is used as auxiliary power for outputting the hydrogen to the outside.

[0037] [9] The energy conversion system according to [6], wherein CO 2 generated by the redox reaction in the chemical conversion unit is recovered.

[0038] Effects of the Invention

[0039] In the present invention, energy conversion from a carbon source to an intermediate medium can be performed based on a solution reaction, and power generation or hydrogen production can be performed from the carbon source without undergoing the form of thermal energy, thereby improving energy conversion efficiency. In addition, such energy conversion can also be performed using low-temperature waste heat.

[0040] Furthermore, in the present invention, even a low-quality carbon source that is difficult to convert into thermal energy by combustion or the like can be utilized.

[0041] Furthermore, depending on the needs, one can choose to directly obtain electricity (generate electricity) or produce hydrogen as a secondary energy source.

[0042] As described above, the present invention can provide a method for producing electric power or a method for producing hydrogen and an energy conversion system that are excellent in energy conversion efficiency even when using a low-quality carbon source and utilizing low-temperature waste heat.

[0043] In addition, the CO 2 generated by the method of the present invention can be easily recovered at a high purity, so the environmental load is small, and the CO 2 can also be reused as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] [ Figure 1 ] Figure 1 It is a schematic diagram of an example of the energy conversion system of the present invention.

[0045] [ Figure 2 ] Figure 2 It is a schematic diagram of an example of a first preferred embodiment of the energy conversion system of the present invention.

[0046] [ Figure 3 ] Figure 3 The temperature and chemical properties of the intermediate medium used in the first preferred embodiment Schematic diagram of the relationship.

[0047] [ Figure 4 ] Figure 4 This is a schematic diagram of the form of recovering CO2 gas using the first preferred form.

[0048] [ Figure 5 ] Figure 5 This is a schematic diagram comparing the energy conversion efficiency of a conventional method and a proposed method using the first preferred embodiment of the present invention.

[0049] [ Figure 6 ] Figure 6 (a) shows the chemical properties of the carbon source (lignite) and the intermediate medium at three temperatures. A diagram showing the size relationship of . Figure 6 (b) shows the chemical relationship between the carbon source (lignite) and several intermediate media. Graph of temperature changes.

[0050] [ Figure 7 ] Figure 7 This is a schematic diagram of an example of performing (B-1) power generation when power is insufficient in the second preferred embodiment of the energy conversion system of the present invention.

[0051] [ Figure 8 ] Figure 8 It is a schematic diagram of the proposed method for recovering CO2 gas when performing power generation when there is a power shortage (B-1) in the second preferred embodiment, and a bar graph after comparison with the existing method.

[0052] [ Fig. 9 ] Fig. 9 This is a schematic diagram of an example of the case where (B-2) hydrogen production is performed when there is excess electric power in the second preferred embodiment of the energy conversion system of the present invention.

[0053] [ Fig.10 ] Fig.10 It is a schematic diagram of the proposed method for recovering CO2 gas when producing hydrogen in the second preferred form (B-2) when there is excess electricity, and a bar graph after comparison with the existing method.

[0054] [ Fig.11 ] Fig.11 (A) is a bar graph showing the yield of generated gas when the reaction temperature of the chemical conversion section is set to 300°C. Fig.11 (B) is a bar graph showing the yield of generated gas when the reaction temperature of the chemical conversion section is set to 250°C.

[0055] [ Fig.12 ] Fig.12 (A) is the XRD pattern of the solid product when Cr2(SO4)3 is reduced. Fig.12 (B) is the XRD pattern of the solid product when Cr(OH)3 is reduced.

[0056] [ Fig.13 ] Fig.13 (A) is a schematic diagram of the material balance in Evaluation Example 1 of Example 1. Fig.13(B) is the value of the evaluation example 1 in Example 1 Schematic diagram of balance. Fig.13 (C) is the combustion process Schematic diagram of an example of equilibrium.

[0057] [ Fig.14 ] Fig.14 (A) is a schematic diagram of the material balance in Evaluation Example 1 of Example 1. Fig.14 (B) is the value of the evaluation example 1 in Example 1 Schematic diagram of balance. Fig.14 (C) is the gasification process Schematic diagram of an example of equilibrium.

[0058] [ Fig.15 ] Fig.15 This is a schematic diagram of an experimental device used in Evaluation Example 3 as a chemical conversion unit in Example 2.

[0059] [ Fig.16 ] Fig.16 These are photographs of samples of the chemical conversion region before and after the reaction under specific reaction conditions of Evaluation Example 3, and a graph showing the relationship between wavelength and absorbance measured by a spectrophotometer.

[0060] [ Fig.17 ] Fig.17 (A) is the reaction time and VO in several reaction conditions of Evaluation Example 3 2+ Ion conversion ratio X VO 2+ of the relationship between . Fig.17 (B) is VO 2+ Ion conversion ratio X VO 2+ Graph showing the relationship between θ and electrochemical conversion E.

[0061] [ Fig.18 ] Fig.18 (A) is an XRD pattern of the solid product in Evaluation Example 4. Fig.18 (B) is a photograph of a solid product under specific conditions of Evaluation Example 4.

[0062] [ Fig.19 ] Fig.19 is a bar graph showing the yield of generated gas in Evaluation Example 4.

[0063] [ Fig. 20 ] Fig. 20 This is a schematic diagram of a model used in the reaction rate analysis of Evaluation Example 5.

[0064] [ Fig.21 ] Fig.21The reaction time and VO in Evaluation Example 5 are recorded based on the calculated value of the reaction rate. 2+ Ion conversion ratio X VO 2+ The graph showing the relationship between is a graph obtained by plotting experimental values ​​in the confirmation experiment.

[0065] [ Fig. 22 ] Fig. 22 This is a schematic diagram of the reactor design of the chemical conversion unit used in Evaluation Example 6.

[0066] [ Fig.23 ] Fig.23 This is a schematic diagram showing the material balance of Evaluation Example 6 of Example 2, the power generation efficiency, and the size of the reactor at that time.

[0067] [ Fig.24 ] Fig.24 Schematic diagram of the energy conversion system used in Evaluation Example 7.

[0068] [ Fig.25 ] Fig.25 This is a graph showing the relationship between the efficiency of the electrolytic reaction of the energy conversion system used in Evaluation Example 7 and the energy conversion efficiency.

[0069] [ Fig.26 ] Fig.26 This is a graph showing the relationship between current density and voltage when hydrogen is produced using the method of Example 2 and the conventional method.

[0070] [ Fig. 27 ] Fig. 27 (A) is a graph showing the relationship between the current density and the efficiency of the electrolysis reaction when hydrogen is produced by the method of Example 2 and the conventional method. Fig. 27 (B) is a graph showing the relationship between the current density and the energy conversion efficiency when hydrogen is produced by the method of Example 2 and the conventional method.

[0071] [ Fig.28 ] Fig.28 is the battery voltage (E Cell The measured value of [V]) and the comprehensive power generation efficiency are compared with VO with an oxidation number of 4 as the intermediate medium. 2+ To V with oxidation number 3 3+ A graph showing the relationship between the reduction rate and the

[0072] [ Fig.29 ] Fig.29 This is a graph (IV curve) showing the relationship between the current (I) and the voltage (V) during power generation in Evaluation Example 10.

[0073] [ Fig.30 ] Fig.30This is a graph showing the relationship between current density and voltage when hydrogen is produced by the method of Evaluation Example 11 and the conventional method. DETAILED DESCRIPTION

[0074] The present invention is described in detail below. The description of the constituent elements described below is sometimes based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In addition, in this specification, the numerical range represented by "to" refers to the range including the numerical values ​​recorded before and after "to" as the lower limit and upper limit.

[0075] [Method for producing electric power or hydrogen]

[0076] The power generation method or hydrogen production method of the present invention is a method for generating power or producing hydrogen from a carbon source, comprising: a chemical conversion step, in which a mixture of a solution containing an intermediate medium and a carbon source is subjected to a chemical reaction of the carbon source. Chemical reaction in the reduced state exceeding the intermediate medium react at a temperature of 100 to 200 °C to oxidize the carbon source and reduce the intermediate medium at the same time; an electrochemical conversion step, wherein an anode of the battery structure in an electrochemical conversion unit having a battery structure is brought into contact with a solution containing the intermediate medium reduced in the chemical conversion step, or a substrate on which the intermediate medium reduced in the chemical conversion step is precipitated is used as the anode of the battery structure, and a cathode of the battery structure is brought into contact with oxygen or air to generate electricity, or a cathode of the battery structure is brought into contact with water to produce hydrogen; and a recycling step, wherein the solution containing the intermediate medium after the electrochemical conversion step is returned to the mixture.

[0077] (Carbon Source)

[0078] The carbon source is not particularly limited.

[0079] In the present invention, a low-quality carbon source can be used as the carbon source. As the carbon source, preferably a low-quality fossil fuel, or a biomass or plastic as a carbon source other than a fossil fuel, more preferably lignite, peat, biomass, polymer, plastic, (organic) sludge or organic waste discharged from the manufacturing industry.

[0080] As a low-quality fossil fuel, lignite is preferred. Lignite refers to coal with a calorific value of 5800 kcal / kg or more and less than 7300 kcal / kg based on pure carbon. Lignite is preferably non-caking coal that does not have caking properties. The carbon content of lignite is about 65% to 78% by mass, the appearance is brown, and it contains a large amount of water.

[0081] Biomass is a renewable organic resource derived from living organisms and is a substance other than fossil resources. Unlike fossil fuels that emit a large amount of CO2 into the atmosphere, biomass can be reproduced and is a carbon-neutral substance. Biomass is roughly divided into dry biomass (wood, bark, waste paper, sawdust, etc.) and wet biomass (sludge, feces, domestic garbage, aquatic plants, etc.). In addition, the moisture content of raw wood is about 50% by mass.

[0082] The polymer is not particularly limited, and for example, a high molecular compound containing carbon atoms can be used, and examples thereof include organic resins, fibers, rubbers, and coatings.

[0083] The plastic is preferably obtained by recycling waste plastics, etc. In addition, as the waste plastic, it is preferable that the waste plastic does not generate gas other than CO2 during the reaction.

[0084] Organic waste discharged from the manufacturing industry refers to organic waste widely discharged from the manufacturing industry. In addition, the organic waste is not particularly limited, and industrial waste, industrial waste, chemical waste, food waste, etc. can be listed. Here, the so-called manufacturing industry is an industry that manufactures goods, and is a concept that widely includes chemical manufacturing, metal manufacturing, machinery manufacturing, food manufacturing, clothing manufacturing, etc.

[0085] The carbon source used in the present invention is not limited by the moisture content. For example, even a carbon source having a moisture content of more than 60% by mass, which is generally considered difficult to use for combustion reactions, can be used in the present invention.

[0086] The carbon source is preferably liquid or solid at room temperature (25°C).

[0087] The carbon source is preferably in a solid or aqueous solution. For example, a powder is preferred as a solid.

[0088] The following shows the moisture content of the solid fuel as a carbon source and the VO at 250°C for 30 minutes. 2+ The reaction rate is shown as an example, but the reaction rate is only shown as an index of the reaction speed of the solid fuel in the present invention, and any solid fuel can be used in the present invention. In addition, the carbon source in the present invention is not limited to this.

[0089] [Table 1]

[0090]

[0091] (Chemical conversion process)

[0092] The method for generating electricity or producing hydrogen of the present invention comprises the following chemical conversion step: in a chemical conversion section, a mixture of a solution containing an intermediate medium and a carbon source is subjected to a chemical reaction of the carbon source. Chemical reaction in the reduced state exceeding the intermediate medium The reaction is carried out at a temperature of 100 to 200 °C, thereby oxidizing the carbon source and reducing the intermediate medium.

[0093] <Intermediate medium>

[0094] In the chemical conversion step, a mixture of a solution containing an intermediate medium and a carbon source can be used.

[0095] Examples of the intermediate medium include materials containing metal elements such as simple metals, metal compounds, metal ions, metal complexes, or mixtures containing metal elements. The intermediate medium can undergo oxidation and reduction, and can take at least two states: an intermediate medium in an oxidized state and an intermediate medium in a reduced state. The intermediate medium in an oxidized state and the intermediate medium in a reduced state can change reversibly.

[0096] The oxidation / reduction of the intermediate medium refers to a reaction that is accompanied by a change in the valence of the metal element.

[0097] The intermediate medium in the oxidized state and the intermediate medium in the reduced state may be in an oxidized state or a reduced state, respectively. For example, the intermediate medium in the reduced state may contain a metal element having an oxidation number exceeding 0 or a metal element having an oxidation number of 0. More specifically, when the intermediate medium in the oxidized state is a Cr element having an oxidation number of 3, the intermediate medium in the reduced state may be a Cr element having an oxidation number of 2, or may be a Cr single substance metal having an oxidation number of 0.

[0098] The intermediate may also have metal ions as part of a complex, such as a central metal or a ligand.

[0099] The intermediate medium in an oxidized state is preferably a metal compound, a metal ion or a mixture thereof, and more preferably a metal compound or a metal ion. The metal compound contained in the intermediate medium in an oxidized state is, for example, a metal oxide (ion).

[0100] As the metal element used for the intermediate medium, any metal element that can make the intermediate medium in a reduced state chemically stable at the reaction temperature of the chemical conversion unit is sufficient. Smaller than the carbon source There are no other restrictions.

[0101] The intermediate medium preferably contains a transition metal element, more preferably contains at least one element of V, Cr, Mn, Fe, Cu, and Zn, and particularly preferably contains at least one element of V, Cr, and Cu.

[0102] Among these, it is preferred that the metal element contained in the intermediate medium is in the form of VO through the carbon source. 2+ →V 3+ Cr3+ →Cr 2+ , Cu 2+ →Cu reduction.

[0103] Here, the reduction reaction is preferably an exothermic reaction from the viewpoint that the reaction temperature can be maintained by the reaction heat itself and the use of external energy such as waste heat can be minimized.

[0104] In addition, from the viewpoint of absorbing waste heat and utilizing it as energy, the reduction reaction is preferably an endothermic reaction (e.g., Cr 3+ →Cr 2+ ).

[0105] In addition, when the temperature during reduction returns to room temperature, the chemical In terms of greatly improving the performance, Cr 3+ →Cr 2+ .

[0106] On the other hand, for VO 2+ →V 3+ , due to the temperature-based chemical The change is small, it is better to say that the chemical Since the temperature is higher, the chemical conversion and electrochemical conversion can be efficiently performed while focusing on the reaction rate and maintaining the temperature high by effectively utilizing waste heat, etc., which is preferred in terms of the above aspects. However, since the reduction reaction in the chemical conversion part is an exothermic reaction, a method of performing external heating only at the start of the reaction can be adopted.

[0107] The intermediate medium in the oxidized state is preferably liquid or solid at room temperature, more preferably liquid.

[0108] <Reduction method (chemical conversion section)>

[0109] In the chemical conversion step, in the chemical conversion section, a mixture of a solution containing an intermediate medium and a carbon source is mixed in a chemical reaction of the carbon source. Chemical reaction in the reduced state exceeding the intermediate medium The reaction is carried out at a temperature of , whereby the carbon source is oxidized and the intermediate medium is reduced.

[0110] The present invention is characterized in that since there is no need to convert the carbon source into heat energy, energy loss is limited to a minimum ( In addition, in the present invention, the reaction is carried out at a reaction temperature lower than the temperature generated by the carbon source in the combustion reaction in the chemical conversion section.

[0111] In this specification, the combustion reaction refers to a reaction in which a carbon source emits heat and light and combines with oxygen.

[0112] Specifically, for example, in the chemical conversion step, in the chemical conversion section, a solution containing an intermediate medium is mixed with a carbon source powder (or liquid), and the temperature of the mixture is raised to a predetermined temperature. The predetermined temperature is the chemical temperature of the carbon source. Chemical reaction in the reduced state exceeding the intermediate medium In addition, the chemical The predetermined temperature is preferably set as low as possible from the viewpoints that the loss of the reaction increases when the difference increases, and a high pressure is required to avoid boiling of the solution. However, it can be set appropriately in consideration of the reaction rate. 2+ →V 3+ In order to start the reaction and increase the reaction rate, it is preferred to appropriately increase the temperature. However, when the reduction reaction is an exothermic reaction, heating from the outside is only required at the beginning, and the temperature can be maintained by the reaction heat as long as the reaction starts.

[0113] Specifically, the reaction temperature in the chemical conversion step is preferably 350°C or less. The reaction temperature can be determined by taking into account the type of carbon source and intermediate medium. The pressure during the reaction can be selected to be a value at which the aqueous solution does not evaporate. For example, in order to prevent the aqueous solution from evaporating at 350°C, a pressure of 15 MPa (150 atmospheres) is required.

[0114] In the chemical conversion process, a solution containing an intermediate medium is mixed with a carbon source powder (or liquid), and the reaction between the intermediate medium and the carbon source is carried out in the liquid. By making the reaction take place in the liquid, it is easy to extract the intermediate medium in a reduced state, and it is easy to avoid mixing the generated gas with the surrounding air and recover the gas.

[0115] In principle, only CO2 gas is produced by the reaction between the intermediate medium and the carbon source in the chemical conversion unit. In actual operation, CO and water vapor may be mixed in, but since CO gas is easily converted into CO2, there is no problem. As for water vapor, it can be easily separated as a liquid by lowering the temperature. As a result, the obtained CO2 can be recovered with a purity of 99.9% or more, or 99.99% or more.

[0116] In the chemical conversion step, when the intermediate medium in a reduced state is solid, the intermediate medium in a reduced state may be precipitated on a substrate separately included in the chemical conversion unit. In this form, the substrate and the intermediate medium in a reduced state precipitated on the substrate may be used as electrodes in the electrochemical conversion unit described later.

[0117] Specifically, for example, an intermediate medium which is a metal ion is reduced to a metal and then precipitated on the substrate.

[0118] In the chemical conversion process, it is not necessary to completely complete the reduction reaction of the intermediate medium in the mixture. (That is, as long as the oxidation of the carbon source proceeds sufficiently.) The mixture used here can be repeatedly used for the reaction with the intermediate medium recovered in the recycling step described later, so the unreacted portion of the intermediate medium will not be immediately lost.

[0119] Furthermore, even when the reaction rate of the intermediate medium is low and the reduction reaction is not completely completed, the subsequent reaction in the electrochemical converter proceeds sufficiently. Fig.17 (b) The explanation thereof will be described later.

[0120] The details of the preferred embodiment of the chemical conversion part will be described later.

[0121] (Electrochemical conversion process)

[0122] The method for generating electricity or producing hydrogen of the present invention includes the following electrochemical conversion process: bringing an electrochemical conversion unit having a battery structure and the anode of the battery structure therein into contact with a solution containing an intermediate medium reduced in the chemical conversion process, or using a substrate in contact with the intermediate medium reduced in the chemical conversion process as the anode of the battery structure, bringing the cathode of the battery structure into contact with oxygen or air to generate electricity, or bringing the cathode of the battery structure into contact with water to produce hydrogen.

[0123] <Electrical power generation method (electrochemical conversion unit)>

[0124] The electrochemical conversion unit includes one electrode (anode), the other electrode (cathode), and a current supply unit connecting the one electrode to the other electrode as a battery structure.

[0125] There is no particular limitation on one electrode and the other electrode. In the present invention, the electrochemical conversion unit is preferably a redox flow type in which one electrode and the other electrode respectively include a pump. The material of one electrode and the other electrode can adopt a known electrode. As an electrode, for example, in addition to using Pt, carbon can also be used to reduce the overvoltage, but it is not limited to this. In addition, in particular as an anode, a substrate having an intermediate medium precipitated on the substrate by the chemical conversion process can also be used.

[0126] In addition, the battery structure may also use a known water electrolysis diaphragm.

[0127] In the electrochemical conversion process included in the power generation method, the anode of the battery structure in the electrochemical conversion unit having the battery structure is brought into contact with a solution containing an intermediate medium reduced in the chemical conversion process, or a substrate on which the intermediate medium reduced in the chemical conversion process is precipitated is used as the anode of the battery structure.

[0128] Examples of a method for bringing the reduced intermediate medium into contact with the anode include a method in which a solution containing the intermediate medium in a reduced state obtained by the chemical conversion step is used as an electrolyte and brought into contact with the anode.

[0129] As a method of using a substrate on which an intermediate medium reduced in a chemical conversion process is deposited as the anode of the battery structure, the following forms can be listed: when the intermediate medium is deposited in a solid phase in the chemical conversion process, the intermediate medium in a reduced state is deposited on a substrate in the chemical conversion process, and in the electrochemical conversion process, the substrate on which the intermediate medium is deposited is used as the anode of the battery structure in the electrochemical conversion unit.

[0130] The form of the substrate is not particularly limited, and any form such as a plate, a rod, or a mesh can be used.

[0131] The material of the substrate is not particularly limited, and a material known as an electrode may be used. However, when the intermediate medium is deposited as a metal, the material may be a material containing the same metal as the intermediate medium.

[0132] However, when the material of the substrate and the intermediate medium in the reduced state are the same metal, the substrate and the precipitated intermediate medium in the reduced state are sometimes inseparable, and the substrate and the intermediate medium become one and play the role of both the anode and the intermediate medium in the reduced state.

[0133] When a method is adopted in which a solution containing an intermediate medium in a reduced state obtained by the chemical conversion step is used as an electrolyte and brought into contact with an anode, the battery structure in the electrochemical converter can be configured as a redox flow battery.

[0134] As the electrolytic solution, a solution in which the intermediate medium that has been reduced in the chemical conversion step is dissolved or a solution in which the intermediate medium is precipitated in the chemical conversion step may be used as it is.

[0135] Here, a battery is formed by supplying oxygen or air to the other electrode (cathode).

[0136] In the electrochemical conversion process (when generating electricity), the oxidation of the intermediate medium does not need to be completely completed. Even if some unreacted parts remain, the solution (electrolyte) and electrode components are reused between chemical reaction parts, so there is no loss.

[0137] <Method for producing hydrogen (electrochemical conversion unit)>

[0138] In a structure substantially the same as that of the above-mentioned battery (electricity generation method), hydrogen is generated by supplying water to the cathode side.

[0139] Depending on the type and state of the intermediate medium, it is sometimes necessary to apply an electrolysis current from the outside. Even in this case, the voltage required for water electrolysis is much lower than that of normal water electrolysis, and the energy conversion efficiency is increased, which can confirm the effect of the contact between the anode and the intermediate medium.

[0140] When an external current is applied, the electrolysis voltage becomes smaller, so a carbon electrode can also be used. In the electrochemical conversion process (when hydrogen is produced), the oxidation of the intermediate medium does not need to be completely completed. Even if a part of the unreacted part remains, the solution (electrolyte) and the electrode components are reused between the chemical reaction parts, so there is no loss. It is important that the carbon source is consumed in the chemical conversion part.

[0141] <Recycling process>

[0142] The power generation method or hydrogen production method of the present invention includes a recycling step of returning the solution containing the intermediate medium after the electrochemical conversion step to the mixture.

[0143] By including a recycling step, the intermediate medium can be reused in the chemical conversion step and the electrochemical conversion step. There is no need to complete the reduction reaction and oxidation reaction of the intermediate medium, which widens the tolerance for changes in reaction conditions. In addition, the carbon source can be consumed efficiently.

[0144] In addition, since the intermediate medium is not consumed in principle, it is also effective from the viewpoint of saving resources.

[0145] <Cooperation between processes>

[0146] For example, in the chemical conversion step of the present invention, a carbon source is added to a solution containing an intermediate medium (oxidized state), and the solution is maintained at a predetermined temperature (chemical state of the carbon source) under pressure. Chemical reaction in the reduced state exceeding the intermediate medium The intermediate medium is reduced in a temperature range of 20°C. Thereafter, the reduced intermediate medium or a solution containing the same is cooled and supplied to the anode of the battery in the electrochemical conversion process of the present invention to extract electrical energy or produce hydrogen. In the electrochemical conversion process, the intermediate raw material is oxidized, so the carbon source is added again after extraction and returned to the chemical conversion process (recycling process).

[0147] When the cooling is performed using a heat pump, the extracted heat can be used for heating or temperature maintenance of the chemical conversion unit.

[0148] When the reaction in the chemical conversion section is carried out in a solution and the intermediate medium in an oxidized state in the electrochemical conversion section is contained in the solution, the chemical conversion section and the electrochemical conversion section can be connected by a pipeline, so that the chemical conversion process, the electrochemical conversion process and the recycling process can be carried out continuously and in parallel.

[0149] The chemical conversion section and the electrochemical conversion section can be combined freely, and a plurality of them can be appropriately combined.

[0150] In the electrochemical converter, multiple cells may be provided to simultaneously generate electricity and produce hydrogen in parallel. In this case, the electricity generated here may be used as auxiliary energy for hydrogen production.

[0151] In the present invention, it is preferred that a recovery step of recovering CO2 gas is included in the post-stage of the chemical conversion step, and a step of separating nitrogen from the gas obtained in the chemical conversion step is not included. In the present invention, since no combustion reaction is performed in the chemical conversion step, the reaction will proceed even if a nitrogen-containing gas such as air is not introduced in the chemical conversion step. In the case where a nitrogen-containing gas such as air is not introduced in the chemical conversion step, since the gas obtained in the chemical conversion step originally contains almost no nitrogen, there is no need for a step of separating nitrogen.

[0152] Other preferred aspects of the energy conversion method of the present invention are the same as the preferred aspects of the energy conversion system of the present invention described later.

[0153] [Energy conversion system]

[0154] The energy conversion system of the present invention comprises: a chemical conversion unit that reduces an intermediate medium from an oxidized state to a reduced state while oxidizing a carbon source; and

[0155] The electrochemical conversion unit includes one electrode, another electrode, and a current supply unit connecting the one electrode to the other electrode, wherein the intermediate medium is oxidized from a reduced state to an oxidized state by the one electrode and the reduced material is reduced by the other electrode.

[0156] At the reaction temperature of the chemical conversion unit, the chemical The chemical state of the intermediate medium exceeds the reduction state The reduction reaction is carried out at a temperature of

[0157] The electrochemical converter outputs at least one of a reduced product of the reduced material and electric power to the outside.

[0158] According to the above structure, the system of the present invention generates electricity or Excellent energy conversion efficiency in the production of high-efficiency secondary energy.

[0159] Here, chemistry It refers to the maximum work that the substance can do before it reaches a state of chemical equilibrium with the standard state of the atmosphere.

[0160] (Reduced material, reduced product of reduced material)

[0161] The reduced product of the reduced material obtained by the electrochemical conversion unit is not particularly limited, but is preferably a high-quality energy resource. As a high-quality energy resource, hydrogen is more preferred, but other examples thereof include hydrocarbons, alcohols, aldehydes, carboxylic acids, CO, and the like.

[0162] Likewise, the reduced material introduced into the electrochemical conversion unit is not particularly limited. When hydrogen is produced as a reduced form of the reduced material, the reduced material is preferably H2O from the viewpoint of obtaining high-purity hydrogen.

[0163] Preferred embodiments of the present invention will be described below.

[0164] <Overview of the energy conversion system of the present invention>

[0165] First, the outline of the energy conversion system of the present invention will be described with reference to the drawings. Figure 1 It is a schematic diagram of an example of the energy conversion system of the present invention.

[0166] Figure 1 The system shown includes a chemical conversion section 11 that reduces an intermediate medium from an oxidized state to a reduced state at a reaction temperature lower than the temperature generated by the carbon source 1 in a combustion reaction.

[0167] The chemical conversion unit 11 preferably has a reactor for reacting the intermediate medium in an oxidized state with the carbon source. The reactor is a reactor capable of achieving the temperature and pressure implemented in the chemical conversion process. Regarding the temperature, it is preferred that the reaction container can be controlled at a predetermined temperature by waste heat or the like.

[0168] In the present invention, from the viewpoint of contact between the intermediate medium and the carbon source, the chemical conversion unit 11 preferably reacts the solid carbon source in a solution containing the intermediate medium in an oxidized state. In this case, the reactor preferably has extrusion flow for both the liquid phase and the solid phase.

[0169] Figure 1 The energy conversion system shown includes a recovery unit 31 for recovering CO2 gas at the rear stage of the chemical conversion unit 11, but it is not necessary to include the recovery unit 31. Figure 1 In the embodiment, the chemical conversion section 11 includes a propeller (stirring member), but may not include a propeller.

[0170] Figure 1 The energy conversion system shown includes an electrochemical conversion unit 21, which includes one electrode 22, another electrode 23 and a power supply unit 24 connecting one electrode 22 with the other electrode 23. While one electrode 22 is used to oxidize the intermediate medium from a reduced state to an oxidized state, the other electrode 23 is used to reduce the reduced material 4.

[0171] exist Figure 1 In the energy conversion system shown, the electrochemical converter 21 outputs at least one of the reduced product 5 of the reduced material and the electric power 6 to the outside.

[0172] exist Figure 1 In the energy conversion system shown, in the chemical conversion unit 11, the intermediate medium 2 in an oxidized state is reduced and converted into the intermediate medium 3 in a reduced state, and in the electrochemical conversion unit 21, the intermediate medium 3 in a reduced state is oxidized and converted into the intermediate medium 2 in an oxidized state. In the present invention, it is preferred to return the intermediate medium 2 in an oxidized state obtained by the electrochemical conversion unit 21 to the chemical conversion unit 11, thereby repeating the oxidation-reduction.

[0173] The electrochemical converter 21 oxidizes the intermediate medium from a reduced state to an oxidized state using one of the electrodes. The electrochemical converter 21 preferably includes a pipe for supplying the intermediate medium in a reduced state to one of the electrodes. The electrochemical converter 21 preferably includes a return pipe for returning the intermediate medium in an oxidized state obtained to the chemical converter 11. The intermediate medium in an oxidized state is reused in the chemical converter 11.

[0174] The electrochemical converter preferably includes a structure capable of outputting at least one of the reduced product of the reduced material and the electric power to the outside. The structure for outputting the electric power to the outside may be concurrently performed by the power supply unit or may be another member.

[0175] The energy conversion system of the present invention also preferably includes a plurality of at least one of the chemical conversion unit 11 and the electrochemical conversion unit 21 .

[0176] When a plurality of the chemical conversion sections 11 are included, their structures, reaction materials reacted therein, and reaction conditions may be the same or different.

[0177] When a plurality of the electrochemical conversion units 21 are included, their structures, reaction materials reacted therein, and reaction conditions may be the same or different.

[0178] Here, it is also preferable that a plurality of the electrochemical converters 21 are included, and the auxiliary power for generating hydrogen is generated and supplied by at least one of the electrochemical converters.

[0179] The chemical conversion part in the energy conversion system of the present invention can be classified into four forms: chemical conversion part a to chemical conversion part d described below.

[0180] Chemical conversion part a: The redox reaction is an exothermic reaction, and the intermediate medium after reduction dissolves in the reaction liquid

[0181] Chemical conversion part b: The redox reaction is an exothermic reaction, and the intermediate medium after reduction is solid

[0182] Chemical conversion part c: The redox reaction is an endothermic reaction, and the intermediate medium after reduction dissolves in the reaction solution

[0183] Chemical conversion part d: The redox reaction is an endothermic reaction, and the intermediate medium after reduction is solid

[0184] In addition, the electrochemical conversion section in the energy conversion system of the present invention can be classified into the following six forms: electrochemical conversion section a to electrochemical conversion section f.

[0185] Electrochemical conversion section a: The anode is brought into contact with a solution containing a reduced intermediate medium, and the cathode is brought into contact with oxygen or air (electricity generation)

[0186] Electrochemical conversion section b: Using a substrate with an intermediate medium deposited as the anode, and bringing the cathode into contact with oxygen or air (power generation)

[0187] Electrochemical conversion section c: The anode is in contact with a solution containing a reduced intermediate medium, the cathode is in contact with water, and no additional power is supplied when hydrogen is produced (hydrogen production)

[0188] Electrochemical conversion section d: A substrate with an intermediate medium deposited thereon is used as the anode, the cathode is in contact with water, and additional power is not supplied when hydrogen is produced (hydrogen production)

[0189] Electrochemical conversion section e: The anode is in contact with a solution containing a reduced intermediate medium, and the cathode is in contact with water to supply additional power for hydrogen production (hydrogen production)

[0190] Electrochemical conversion section f: Using a substrate with an intermediate medium deposited thereon as the anode, making the cathode in contact with water, and supplying additional power for hydrogen production (hydrogen production)

[0191] Examples of the combination of a chemical conversion unit and an electrochemical conversion unit in the energy conversion system of the present invention include the following systems 1 to 12.

[0192] System 1: Chemical conversion unit a and electrochemical conversion unit a

[0193] System 2: Chemical conversion unit a and electrochemical conversion unit c

[0194] System 3: Chemical conversion unit a and electrochemical conversion unit e

[0195] System 4: Chemical conversion unit b and electrochemical conversion unit b

[0196] System 5: Chemical conversion unit b and electrochemical conversion unit d

[0197] System 6: Chemical conversion unit b and electrochemical conversion unit f

[0198] System 7: Chemical conversion unit c and electrochemical conversion unit a

[0199] System 8: Chemical conversion unit c and electrochemical conversion unit c

[0200] System 9: Chemical conversion unit c and electrochemical conversion unit e

[0201] System 10: Chemical conversion unit d and electrochemical conversion unit b

[0202] System 11: Chemical conversion unit d and electrochemical conversion unit d

[0203] System 12: Chemical conversion unit d and electrochemical conversion unit f

[0204] Furthermore, the energy conversion system of the present invention may be a composite system including a plurality of different systems among the systems 1 to 12 described above.

[0205] <First preferred embodiment>

[0206] A first preferred embodiment of the energy conversion system of the present invention is described below.

[0207] The first preferred embodiment is a specific example of a case where no additional power supply means is provided during hydrogen production, and is a specific example of the system 1 , the system 2 , the system 4 , the system 5 , the system 7 , the system 8 , the system 10 , or the system 11 .

[0208] In particular, a first preferred form of the energy conversion system preferably utilizes chemical Highly efficient waste heat utilization form with low temperature dependence.

[0209] Waste heat utilization includes any of the following forms: a form of utilizing waste heat in an endothermic reaction in a chemical conversion unit (the system 7, the system 8, the system 10, the system 11), and a form of utilizing waste heat in maintaining and adjusting the ambient temperature (the system 1, the system 2, the system 4, the system 5).

[0210] Figure 2 It is a schematic diagram of an example of a first preferred embodiment of the energy conversion system of the present invention.

[0211] Figure 2 The energy conversion system shown is Figure 1 The energy conversion system shown, wherein the chemical conversion unit 11 further includes a waste heat supply component 33, and waste heat 8 is supplied from the waste heat supply component 33. The waste heat 8 is not particularly limited as long as it is heat discarded from power plants, factories, waste disposal sites, etc. As examples of waste heat, heat discarded from thermal mechanisms such as power plants, factories, waste disposal sites, etc. can be cited. The temperature of the waste heat is preferably above the reaction temperature of the chemical conversion unit. In addition, the chemical conversion unit only needs to have a heat supply component, and the waste heat supply component is not required. The heat supply component in the chemical conversion unit can also be, for example, a solar energy supply component that supplies solar energy.

[0212] exist Figure 2 In the example, using H2O (or H + ) as the reduced material 4 to simultaneously produce (generate together) H2 as the reduced product 5 of the reduced material and electricity 6, the above example is also preferred in terms of being able to produce hydrogen without generating O2. Figure 2 In the embodiment shown, the chemical conversion part may be any one of the chemical conversion part a to the chemical conversion part d. In addition, the electrochemical conversion part may be any one of the electrochemical conversion part c or the electrochemical conversion part d. That is, Figure 2 The illustrated form is a form corresponding to the system 2 , the system 5 , the system 8 , or the system 11 .

[0213] In a first preferred embodiment of the energy conversion system, the chemical composition of the intermediate medium in the electrochemical conversion unit is Greater than the chemical source of carbon in the chemical conversion unit In addition, at this time, the chemical in the electrochemical conversion unit Chemical transformation department The chemical That is, it is not limited to comparing chemical For comparison, the chemical In addition, in the first preferred embodiment of the energy conversion system, the chemical composition of the intermediate medium in the electrochemical conversion unit is preferably Greater than the chemical concentration of the intermediate medium in the chemical conversion unit .

[0214] Figure 3 The temperature and chemical properties of the intermediate medium used in the first preferred embodiment of the energy conversion system A schematic diagram of the relationship between Figure 3 It can be seen that the chemical reaction temperature of the intermediate medium (in a reduced state) is Less than carbon source ( Figure 3 Chemical substances recorded as reaction raw materials And make the chemical of the intermediate medium (in the reduced state) in the electrochemical conversion unit Greater than the chemical concentration of the intermediate medium (in the reduced state) in the chemical conversion section , thus, when the reduction reaction of the intermediate medium is an endothermic reaction, the reaction in the chemical conversion unit is carried out by introducing waste heat or the like as additional energy into the chemical conversion unit. In addition, it is known that in this case, the reaction in the electrochemical conversion unit is also easy to proceed, and electricity or hydrogen can be produced efficiently. High efficiency secondary energy.

[0215] In the first preferred embodiment of the energy conversion system, the reaction in the chemical conversion section is preferably an endothermic reaction, that is, preferably chemical conversion section c or chemical conversion section d, preferably system 7, system 8, system 10 or system 11.

[0216] In a first preferred aspect of the energy conversion system, a heat exchange section may be included between the chemical conversion section and the electrochemical conversion section, and more energy can be effectively utilized by making the reaction temperature in the electrochemical conversion section lower than the reaction temperature in the chemical conversion section.

[0217] Furthermore, from the perspective of improving energy conversion efficiency, the first preferred form of the system preferably includes a heat return piping, which can return the heat recovered from the heat exchange unit to the waste heat supply component (or any second heat exchange unit arranged in the front stage of the chemical reaction unit).

[0218] Figure 4 Schematic diagram of the first preferred form of the system for recovering CO2 gas. Figure 4 As shown, in the case where waste heat is introduced into a chemical conversion unit, biomass or lignite used as a carbon source is oxidized, and the intermediate medium in an oxidized state is reduced, and the chemical conversion unit includes a recovery unit for recovering CO2 gas in the subsequent stage, the gas (gas containing CO2) obtained by the chemical conversion unit does not contain nitrogen and does not require nitrogen separation, so it is easy to recover high-purity CO2 gas.

[0219] Compared with the existing methods, the use of Cr (III)The first preferred form of the system for producing electricity or hydrogen as an intermediate medium in an oxidized state, in which CO2 gas is recovered (the proposed method), has a very high energy conversion efficiency. Figure 5 This is a schematic diagram comparing the energy conversion efficiency of a conventional method and a proposed method using the first preferred embodiment of the system of the present invention.

[0220] As a conventional method, the conversion efficiency of converting the energy of biomass or lignite (the energy is set to 100) into H2 by gasification is about 70%, and if nitrogen separation is also taken into account, the conversion efficiency of recovering CO2 by conventional methods is about 60%. In addition, the efficiency of generating electricity from waste heat (139) at about 300°C using a thermoelectric conversion element is about 10% (about 14).

[0221] In contrast, in the proposed method, waste heat (139) at about 300°C is input to convert the energy (100) of biomass or lignite into Cr by a chemical conversion unit. (II) The endothermic reaction is carried out and CO2 gas is recovered. Water is used for Cr in the electrochemical conversion unit. (II) When reoxidized, electricity (31) and H2 (128) can be generated simultaneously. The energy conversion efficiency is 100%×(128+31) / (100+139)=about 67%.

[0222] Therefore, compared with the existing method (60+14=74) when CO2 gas recovery is involved, the energy conversion efficiency is approximately twice as high in the proposed method (128+31=159).

[0223] Therefore, the energy conversion system of the present invention (common to the first preferred embodiment and the second preferred embodiment) is also a so-called carbon dioxide capture, utilization, and storage ready (CCUS ready) method that can be easily combined with a recovery process for recovering CO2 gas. In this specification, the situation in which CCUS equipment is prepared to be additionally installed at an appropriate time in the future is referred to as "CCUS ready". CCUS is a technology for the recovery, effective utilization, and storage of carbon dioxide (Carbon dioxide Capture, Utilization and Storage). In addition, in the case of ocean dumping of CO2 gas, based on domestic laws or guidelines in Japan, it is required to separate nitrogen from CO2-containing gas in the recovery of CO2 gas to obtain high-purity CO2 gas, and there is a problem that the energy or cost required for the process of separating the nitrogen is large.

[0224] Figure 6(a) shows the chemical properties of the carbon source (lignite) and the intermediate medium for representative temperatures. According to the value of Figure 6 (a) It can be seen that when the Cr compound with an oxidation number of 3 is changed to the Cr compound with an oxidation number of 2, if the reaction temperature of the chemical conversion unit is set to 300°C (calculated to be 255°C or above), the chemical properties of the intermediate medium (in a reduced state) can be reduced. Smaller than the carbon source Similarly, for example, when a Cr compound with an oxidation number of 3 is changed into a Cr compound with an oxidation number of 1 or a Cr compound with an oxidation number of 0, when a Ni compound with an oxidation number of 2 is changed into a Ni compound with an oxidation number of 0, and when a vanadium compound with an oxidation number of 3 is changed into a vanadium compound with an oxidation number of 2, the chemical properties of the intermediate medium can be increased by making the reaction temperature high. Smaller than the carbon source For example, the reaction temperature when a Cr compound with an oxidation number of 3 is changed into a Cr compound with an oxidation number of 1 or a Cr compound with an oxidation number of 0 may be 300° C. or higher, the reaction temperature when a Ni compound with an oxidation number of 2 is changed into a Ni compound with an oxidation number of 0 may be 310° C. or higher, and the reaction temperature when a vanadium compound with an oxidation number of 3 is changed into a vanadium compound with an oxidation number of 2 may be 290° C. or higher. Figure 6 (b) shows the chemical composition of lignite and the intermediate medium after reduction. A graph of the temperature changes is provided, and the valences of substances other than lignite after reduction are recorded.

[0225] In addition, according to Figure 6 (b) It can be seen that if the reaction temperature of the electrochemical conversion unit is set to 25°C (room temperature), the chemical reaction of the intermediate medium in the reduced state in the electrochemical conversion unit can be reduced. The chemical temperature of the intermediate medium in the reduced state in the chemical conversion section is less than (300°C) .

[0226] In a first preferred embodiment of the energy conversion system, the reaction in the chemical conversion unit (reduction reaction of the intermediate medium) is preferably an endothermic reaction (for example, Cr 3+ →Cr 2+ ). In addition, the reaction in the chemical conversion unit is an endothermic reaction, Cr 3+ →Cr 2+ In the case of the above, from the viewpoint of waste heat utilization and pressure when using an aqueous solution to carry out the reaction in the chemical conversion unit, the reaction temperature in the chemical conversion unit is more preferably 255°C to 350°C, particularly preferably 280°C to 320°C.

[0227] In addition, the reaction temperature of the chemical conversion section is as long as the chemical reaction temperature of the intermediate medium in the reduced state is Smaller than the carbon source conditions.

[0228] In the first preferred embodiment of the energy conversion system, the intermediate medium preferably contains Cr element. More preferably, the intermediate medium in the oxidized state is Cr with an oxidation number of 3. (III) , the intermediate medium in the reduced state is Cr with an oxidation number of 2 (II) 、Cr with oxidation number 1 (I) or Cr with oxidation number 0 (0) , and more preferably Cr with oxidation number 1 (I) or Cr with oxidation number 0 (0) Generally speaking, if the reduction degree is increased, It is preferred that the reduction degree be increased, but an appropriate reduction degree can be selected in consideration of the relationship with the treatment conditions of both the chemical conversion section and the electrochemical conversion section.

[0229] <Second preferred embodiment>

[0230] The second preferred form of the energy conversion system is as follows: the electrochemical conversion unit includes an additional power supply component, additional power is supplied from the additional power supply component, and the electrochemical conversion unit outputs the reduced body of the reduced material to the outside. In the following description, (B-2) is this form. The second preferred form is a case where there is an additional power supply component when producing hydrogen, that is, a specific example of the electrochemical conversion unit e or the electrochemical conversion unit f, and is a specific example of the system 3, system 6, system 9 or system 12.

[0231] In the second preferred form of the energy conversion system, it is preferred that (B-1) power generation when power is insufficient and (B-2) hydrogen production when power is excessive can be performed simultaneously. That is, it is preferred that the following form is used: when power supply is insufficient relative to power demand, the electrochemical conversion unit outputs power to the outside, and when power supply is excessive relative to power demand, the electrochemical conversion unit outputs the reduced form of the reduced material to the outside.

[0232] Specifically, the second preferred form of the energy conversion system is more preferably that the electrochemical conversion unit includes a control unit, and the control unit controls in the following manner: when the power supply is insufficient relative to the power demand, the electrochemical conversion unit outputs power to the outside, and when the power supply is excessive relative to the power demand, the electrochemical conversion unit outputs the reduced form of the reduced material to the outside.

[0233] Here, the electrochemical conversion unit that outputs the electricity to the outside (hereinafter also referred to as "electrochemical conversion unit A") and the electrochemical conversion unit that outputs the reduced form of the reduced material to the outside (hereinafter also referred to as "electrochemical conversion unit B") may be the same as or different from each other.

[0234] When the electrochemical conversion section A and the electrochemical conversion section B are different, they may be included in the same system or in different systems.

[0235] That is, the system of the present invention also includes a complex of systems including two or more systems including an electrochemical conversion unit.

[0236] When the electrochemical conversion section A and the electrochemical conversion section B are configured as the same electrochemical conversion section, there are advantages such as miniaturization of the system and reduction in manufacturing cost.

[0237] In addition, when the electrochemical conversion section A and the electrochemical conversion section B are set as different electrochemical conversion sections, there are advantages such as wide freedom in design: in the electrochemical conversion section A, an electrode structure, a catalyst, etc. suitable for outputting electric power to the outside can be selected, and in the electrochemical conversion section B, an electrode structure, a catalyst, etc. suitable for outputting a reduced body to the outside can be selected.

[0238] In addition, the number of electrochemical conversion sections A and electrochemical conversion sections B is not particularly limited.

[0239] For example, the energy conversion system of the present invention can take various forms such as: a system including multiple electrochemical conversion units B relative to one electrochemical conversion unit A, a system that is a composite of a system including one electrochemical conversion unit A and multiple systems including one electrochemical conversion unit B, etc.

[0240] ((B-1) Power generation in case of power shortage)

[0241] Figure 7 It is a schematic diagram of an example of power generation when (B-1) power shortage is performed in the second preferred form of the system of the present invention. (B-1) is a specific example of electrochemical conversion unit a or electrochemical conversion unit b, and is a specific example of the system 1, system 4, system 7 or system 10.

[0242] Figure 7 The system shown is Figure 1 The system shown in the figure, wherein the electrochemical converter 21 further includes a control unit 41, and the control unit 41 controls the electrochemical converter 21 to output the electric power 6 to the outside when the electric power supply is insufficient relative to the electric power demand. In addition, Figure 7The system shown further includes an additional power supply unit 42, but the additional power supply unit 42 may not be used in power generation when (B-1) power is insufficient.

[0243] exist Figure 7 In the example, in the chemical conversion unit, VO 2+ As the intermediate medium 2 in the oxidized state, V is obtained as the intermediate medium 3 in the reduced state. 3+ At the same time, the carbon source 1 is oxidized. Figure 7 In the example of , the reaction temperature of the chemical conversion section can be set to 250° C. or less.

[0244] In addition, Figure 7 In the example of the electrochemical conversion unit, O2 is used as the reduced material 4, and H2O as the reduced product 5 of the reduced material is obtained, while V2 as the intermediate medium 3 in the reduced state is obtained. 3+ Regeneration of VO2 as an intermediate medium in an oxidized state 2+ , and output power 6.

[0245] Figure 8 The following is a diagram showing a proposed method for recovering CO2 gas during power generation in the event of power shortage (B-1) and a bar graph showing a comparison with the existing method. Figure 8 As shown, in a form in which biomass or lignite used as a carbon source is oxidized in a chemical conversion unit, and the intermediate medium in an oxidized state is reduced, and the chemical conversion unit includes a recovery unit for recovering CO2 gas in the subsequent stage, the gas (gas containing CO2) obtained by the chemical conversion unit does not contain nitrogen and does not require nitrogen separation, so it is easy to recover high-purity CO2 gas.

[0246] Figure 7 An example of the reaction in the chemical conversion unit is as follows.

[0247] CH 0.84 O 0.34 +1.66H2O→CO2+4.16H + +4.16e -

[0248] VO 2+ +2H + +e - →V 3+ +H2O

[0249] CH 0.84 O 0.34 +4.16VO 2+ +4.16H + →CO2+2.5H2O+4.16V 3+

[0250] Figure 7 An example of the reaction in the electrochemical conversion unit is as follows.

[0251] V 3+ +H2O→VO 2+ +2H + +e - 0.337V

[0252] O2+4H + +4e - →2H2O 1.23V

[0253] 4V 3+ +2H2O+O2→4VO 2+ +4H + E0=0.89V

[0254] therefore, Figure 7 The theoretical power of the energy conversion system shown is,

[0255] 4.16[mol-e - / mol-C]×0.89[V]×[96500C / mol-C]

[0256] =357.3 kJ / mol-C.

[0257] The calorific value of lignite is 451.2 kJ / mol-C, so Figure 7 The theoretical power generation efficiency of the energy conversion system shown is 0.79 (=357.3 / 451.2).

[0258] In this case, the practical power generation efficiency is 0.79×0.7=0.55 using a coefficient of 0.7 that takes into account the efficiency of electrochemical conversion or other energy losses.

[0259] When performing power generation when there is a power shortage (B-1), it is possible to simultaneously resolve conflicting issues such as the deterioration of fossil fuels due to the depletion of carbon sources, the separation and recovery of CO2 (CCUS), the utilization of biomass, etc., the response to load changes (including the balance between power demand and power supply), and the improvement of power generation efficiency.

[0260] The results of comparison between the case (B-1) (proposed method), the conventional method (boiler) and the integrated gasification combined cycle (IGCC) (coal gasification combined power plant) are shown in Table 2 below.

[0261] [Table 2]

[0262]

[0263] [2] Cost and Performance Baseline for Fossil Energy Plants, Volume 1b, Rev 2b, U.S. Department of Energy / National Energy Technology Laboratory (DOE / NETL) - 2010 / 1397

[0264] According to Table 2, in the integrated combustion power generation method (IGCC), the power generation efficiency decreases by about 10% after the introduction of CCUS, and most of the energy required for the introduction is the separation / recovery process. This is also the case in the existing method (boiler).

[0265] In contrast, in the proposed method (the second preferred form of the energy conversion system (the case of performing (B-1) power generation when power is insufficient)), since the generated gas in the chemical conversion unit is CCUS-ready, the reduction in power generation efficiency when CCUS is introduced can be suppressed. Therefore, the second preferred form of the energy conversion system preferably includes a recovery unit for recovering CO2 gas at the subsequent stage of the chemical conversion unit, and in the case of separating and recovering CO2, higher power generation efficiency can be obtained, especially compared with existing methods.

[0266] exist Figure 8 The results of the above description are summarized in the bar graph on the right side of the paper. As a conventional method, the conversion efficiency when converting the energy of biomass or lignite (the energy thereof is set to 100) into electricity using a boiler is about 20% (10% to 30%) according to Table 1. Furthermore, the conversion efficiency when recovering CO2 using the conventional method is further reduced by about 10% to about 10%.

[0267] On the other hand, in the proposed method, the energy (100) of biomass or lignite can be converted into electric power with a practical power generation efficiency of 0.55 (55%) as calculated above.

[0268] In the second preferred embodiment of the energy conversion system, the reaction in the chemical conversion unit is preferably an exothermic reaction from the viewpoint of maintaining the temperature and continuing the reaction by using its own reaction heat when there is no heat supplied from the outside. However, it may also be an endothermic reaction.

[0269] In addition, in the second preferred form of the energy conversion system, from the perspective of the pressure when using an aqueous solution to carry out a reaction in the chemical conversion section, the reaction temperature in the chemical conversion section is preferably 25°C (room temperature) to 350°C, from the perspective of the reaction rate, it is preferably above 100°C and below 350°C, and from the perspective of using lignite as a carbon source, it is particularly preferably above 220°C and below 250°C.

[0270] In the second preferred embodiment of the energy conversion system, the intermediate medium preferably contains the Cu element or the V element. From the viewpoint of improving the energy conversion efficiency at high temperature in electrochemical conversion, it is more preferable to contain the V element. It is more preferable that the intermediate medium in the oxidized state is Cu with an oxidation number of 2. (II) or V with oxidation number 4 (IV) , the intermediate medium in the reduced state is Cu with an oxidation number of 0 (0) , V with oxidation number 3 (III) or V with oxidation number 2 (II) .

[0271] In a second preferred embodiment of the energy conversion system, the chemical composition of the intermediate medium in the reduced state in the electrochemical converter is The chemistry of carbon sources in comparable chemical conversion units Bigger, but can also be the same or smaller.

[0272] ((B-2) Hydrogen production when there is excess electricity)

[0273] Fig. 9 This is a schematic diagram of an example of the case where (B-2) hydrogen production is performed when there is excess electric power in the second preferred embodiment of the energy conversion system of the present invention.

[0274] Fig. 9 The energy conversion system shown is Figure 7 In the energy conversion system shown, the control unit 41 controls the electrochemical converter 21 so that the reduced product 5 of the reduced material is output to the outside when the power supply is in excess of the power demand. Fig. 9 The energy conversion system shown also includes an additional power supply component 42, and additional power 7 is supplied from the additional power supply component 42 to the electrochemical conversion unit. It is preferred that the additional power supply is surplus power when it is in excess of the power demand, and it is particularly preferred to be surplus power from renewable energy. In particular, among renewable energy sources, sunlight sometimes generates solar power that exceeds the power demand during the day, so it is preferred to use the surplus power from sunlight as the additional power of the present invention. In addition, power obtained by power generation based on the present invention can also be supplied.

[0275] exist Fig. 9 In the example, using H2O (or H +) as the reduced material 4 to produce H2 as the reduced product 5 of the reduced material.

[0276] Fig.10 It is a schematic diagram of the proposed method for recovering CO2 gas when producing hydrogen in the second preferred form of the energy conversion system (B-2) when there is excess electricity, and a bar graph comparing it with the existing method.

[0277] As a conventional method, the conversion efficiency of converting the energy of biomass or lignite (the energy is set to 100) into H2 by gasification is about 70%, and if nitrogen separation is also taken into account, the conversion efficiency of recovering CO2 by conventional methods is about 60%. In addition, the efficiency of producing hydrogen from surplus electricity (43) by water electrolysis is about 70% (about 30).

[0278] In contrast, in the proposed method, the energy (100) of biomass or lignite can be converted into V (III) Cu (0) , CO2 gas is recovered, and the surplus power is introduced into the electrochemical conversion unit to produce H2 by reducing water. The energy conversion efficiency of the proposed method is about 90% according to Evaluation Example 8 of Example 2 described later.

[0279] Therefore, compared with the existing method (60+30=90) when CO2 gas recovery is involved, the energy conversion efficiency is approximately 1.4 times in the proposed method (90+39=129).

[0280] Example

[0281] The present invention is described in more detail below by enumerating examples and comparative examples. The materials, usage amounts, ratios, processing contents, processing procedures, etc. shown in the following examples may be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed restrictively by the specific examples shown below.

[0282] [Example 1]

[0283] Chemical The implementation of the energy conversion system of Example 1 for high-efficiency waste heat conversion with respect to temperature dependence of .

[0284] Follow the process below Figure 2 The demonstration experiment of the energy conversion system described in the document confirmed that electricity and H2 can be generated simultaneously by supplying waste heat.

[0285] The chemical conversion unit is configured to supply waste heat and to perform an endothermic reaction at 250°C to 300°C. Lignite is used as a carbon source. In the chemical conversion unit, an aqueous solution of Cr(OH)3, which is a Cr compound with an oxidation number of 3, is used as an intermediate medium in an oxidized state. In the chemical conversion unit, lignite is oxidized to form CO2, and the intermediate medium in an oxidized state is reduced to form an intermediate medium in a reduced state of CrO with an oxidation number of 2.

[0286] The CO 2 generated in the chemical conversion section is recovered almost 100% (more than 99% by volume) in the recovery section (including components of the separator and the recovery section) connected between the chemical conversion section and the electrochemical conversion section.

[0287] The intermediate medium in a reduced state generated in the chemical conversion section is moved to the electrochemical conversion section.

[0288] The electrochemical conversion unit is configured to include one electrode, another electrode, and a current-carrying unit connecting them, and is configured to be a redox liquid flow type. An intermediate medium in a reduced state is supplied to one of the electrodes, and the intermediate medium CrO in a reduced state is oxidized into Cr(OH)3 in an oxidized state, and the obtained Cr(OH)3 is returned to the chemical conversion unit via a return pipe for reuse. However, the obtained Cr(OH)3 can also be temporarily extracted to the outside and then appropriately reused in the chemical conversion unit.

[0289] For the other electrode, water is used as a reducing material, water is reduced to produce H2, and then extracted to the outside. Electric power is extracted from the power supply part to the outside.

[0290] The reaction temperature in the electrochemical conversion unit was set to room temperature (25° C.).

[0291] <Confirmation of the progress of the reaction>

[0292] (Lignite and Cr 3+ Reaction: Gas Analysis)

[0293] The chemical conversion unit oxidizes the lignite by gas analysis and converts the Cr compound (Cr (III) ) is reduced to a Cr compound with an oxidation number of 2, and the following reaction is confirmed.

[0294] CH 0.84 O 0.34 +4.16Cr 3+ +1.66H2O→CO2+4.16Cr 2+ +4.16H +

[0295] Fig.11(A) is a bar graph showing the yield of generated gas when the reaction temperature of the chemical conversion section is set to 300°C. Fig.11 In (A), the yield results of the generated gas in the case of a control without Cr compound, in the case of Cr2(SO4)3, and in the case of Cr(OH)3 are shown in order from the left side of the paper.

[0296] Fig.11 (B) is a bar graph showing the yield of generated gas when the reaction temperature of the chemical conversion section is set to 250°C. Fig.11 In (B), the yield results of the generated gas in the case of Cr2(SO4)3 and Cr(OH)3 are shown in order from the left side of the paper.

[0297] according to Fig.11 (A) and Fig.11 (B) It can be seen that when the reaction temperature of the chemical conversion unit is set to 300°C, the reaction temperature of lignite and Cr 3+ The CO2 yield was significantly increased by the reaction. In addition, in the case of Cr(OH)3, the generation of H2 was confirmed. Based on these results, it can be seen that lignite is oxidized by Cr compounds (Cr (III) ) oxidation.

[0298] (Lignite and Cr 3+ Reaction: Analysis of solid products)

[0299] The solid product was analyzed by setting the reaction temperature of the chemical conversion section to 300°C, and the Cr compound (Cr (III) ) is reduced to a Cr compound with an oxidation number of 2, and the following reaction is confirmed.

[0300] CH 0.84 O 0.34 +4.16Cr 3+ +1.66H2O→CO2+4.16Cr 2+ +4.16H +

[0301] Fig.12 (A) is the X-ray diffraction (XRD) pattern of the solid product when Cr2(SO4)3 is reduced. Fig.12 (A) It can be seen that CrH (I) and CrC (0) .

[0302] Fig.12 (B) is the XRD pattern of the solid product when Cr(OH)3 is reduced. Fig.12 (A) It can be seen that CrO is generated (II).

[0303] according to Fig.12 (A) and Fig.12 (B) It can be seen that when the reaction temperature of the chemical conversion unit is set to 300°C, the reaction temperature of lignite and Cr 3+ The yield of CO2 increased significantly due to the reaction of Cr(OH)3. In addition, the generation of H2 was confirmed in the case of Cr(OH)3. From these results, it can be seen that when the reaction temperature of the chemical conversion unit is set to 300°C, Cr (III) Reduced by lignite.

[0304] <Evaluation Example 1>

[0305] In Evaluation Example 1, the energy conversion system of Example 1 was used to evaluate the (III) In Evaluation Example 1, the chemical conversion unit includes a waste heat supply component, and a process in which waste heat is supplied by the waste heat supply component is performed in the energy conversion system of Example 1.

[0306] Fig.13 (A) is a schematic diagram of the material balance in Evaluation Example 1 of the energy conversion system of Example 1. Fig.13 (B) is the energy conversion system of Example 1 in Evaluation Example 1 Schematic diagram of the balance. In addition, Fig.13 As shown in (B), the energy conversion system of Example 1 used in Evaluation Example 1 includes a heat return pipe 34.

[0307] on the other hand, Fig.13 (C) is the combustion process Schematic diagram of an example of equilibrium.

[0308] According to the results of Evaluation Example 1, compared with the combustion process, the energy conversion system of Example 1 can utilize waste heat, and The loss is small.

[0309] <Evaluation Example 2>

[0310] In Evaluation Example 2, the energy conversion system of Example 1 was used to evaluate the (III) In Evaluation Example 2, the chemical conversion unit also includes a waste heat supply component, and a process in which waste heat is supplied by the waste heat supply component is performed in the energy conversion system of Example 1.

[0311] Fig.14 (A) is a schematic diagram of the material balance in Evaluation Example 1 of the energy conversion system of Example 1. Fig.14 (B) is the energy conversion system of Example 1 in Evaluation Example 1 Schematic diagram of balance.

[0312] on the other hand, Fig.14 (C) is the gasification process Schematic diagram of an example of equilibrium.

[0313] The results of Evaluation Example 2 show that the energy conversion system of Example 1 can utilize waste heat and has a high yield compared to the gasification process. Furthermore, it is also found that the energy conversion system of Example 1 is advantageous in that it does not require separation of nitrogen from CO2 as the generated gas compared to the gasification process.

[0314] [Example 2]

[0315] The implementation of the energy conversion system of Example 2 that can produce hydrogen with high efficiency was studied.

[0316] The energy conversion system of the second embodiment includes a control unit capable of switching Figure 7 (B-1) Power generation when power is insufficient and Fig. 9 The energy conversion system of Example 1 was manufactured in the same manner as described above except for the above-described (B-2) hydrogen production during excess power. The energy conversion system of Example 2 was tested for verification according to the following procedure.

[0317] <(B-1) Verification of power generation during power shortage>

[0318] (Evaluation Example 3)

[0319] In Evaluation Example 3, the Fig.15 The experimental setup described. Fig.15 This is a schematic diagram of an experimental device used in Evaluation Example 3 as a chemical conversion unit in the energy conversion system of Example 2.

[0320] The reaction conditions are as follows.

[0321] Reaction temperature: 200℃ or 250℃.

[0322] Reaction time: 10 minutes to 180 minutes.

[0323] Pressure: 4MPa.

[0324] Reaction liquid volume: 0.7mL or 7mL.

[0325] Intermediate medium: VOSO4 aqueous solution.

[0326] Additive: H2SO4 aqueous solution.

[0327] Carbon source: Lignite (Loy Yang coal) or eucalyptus.

[0328] The gas analysis method is as follows.

[0329] Gas chromatography (Shimadzu, GC-12A)

[0330] Column: Porapak-Q, Molecular Sieve 5A

[0331] Detector: Thermal Conductivity Detector (TCD), Flame Ionization Detector (FID)

[0332] The analysis method of the liquid is as follows.

[0333] Ultraviolet-Visible-Near Infrared Ray (UV-vis-NIR) (Shimadzu, UV-3100PC)

[0334] The analysis method of the solid residue is as follows.

[0335] Carbon / Hydrogen / Nitrogen (CHN) (Yanako, MT-6)

[0336] Fig.16 The specific reaction conditions of Evaluation Example 3 (reaction time 250°C, reaction time 25 minutes, initial VO 2+ Concentration C VO 2+ ,0 =0.50mol / L, initial carbon concentration C c,0 =1.0mol / L, initial H2SO4 concentration C H2SO4,0 =3.0 mol / L) before and after the reaction of the chemical conversion unit, and a graph showing the relationship between wavelength and absorbance. Fig.16 It can be seen that under the specific reaction conditions, VO with an oxidation number of 4 as an intermediate medium in an oxidized state in the chemical conversion unit 2+ The ion is reduced to V with oxidation number 3, which is an intermediate in the reduction state. 3+ ions, the reaction proceeds. That is, according to Fig.16 The results suggest that under the specific reaction conditions, the oxidation reaction of lignite as a carbon source proceeds.

[0337] Fig.17 (A) is the reaction time and VO in several reaction conditions of Evaluation Example 3 2+ The conversion ratio of ions is the conversion, X VO 2+(Conversion,X VO 2+ ) (unit: none). Fig.17 (A) It can be seen that when biomass (eucalyptus) is used as the carbon source, the above-mentioned VO 2+ Ion to V 3+ The reduction reaction of VO ions is carried out at a temperature of at least 125°C to 200°C. In addition, it is known that when lignite is used as a carbon source, the reduction reaction of VO ions is carried out at a temperature of 250°C. 2+ Ion to V 3+ The reduction reaction of the ions is carried out at a temperature of at least 125°C to 200°C.

[0338] in addition, Fig.17 (B) is VO 2+ The conversion ratio of ions is the conversion, X VO 2+ (Conversion,X VO 2+ ) and electrochemical conversion E (unit: V). Fig.17 (B) It can be seen that even if VO 2+ The conversion ratio of ions is the conversion, X VO 2+ (Conversion,X VO 2+ ) is as low as 0.2, and a sufficient electromotive force of 0.86 V can be obtained in the electrochemical converter of the subsequent stage. In other words, it can be seen that a sufficient voltage can be obtained in the electrochemical converter even in a state where the reduction of the intermediate medium is insufficient.

[0339] (Evaluation Example 4: Cu and biomass)

[0340] In Evaluation Example 4, the Cu 2+ Ions replace VO 2+ ions as the intermediate medium, the reaction temperature was set to 300°C, the reaction time was set to 120 minutes, and the initial Cu 2+ Concentration C Cu 2+ ,0 =1.0mol / L, initial carbon concentration C c,0 =1.0 mol / L, 0.47 mol / L or 0.30 mol / L, and the evaluation was performed. In Evaluation Example 4, the solid product after the reaction was evaluated by XRD and photographs, and the generated gas after the reaction was evaluated by gas analysis.

[0341] In addition, in the chemical conversion section, while oxidizing the biomass (cellulose), Cu with an oxidation number of 2 is converted into2+ The reaction of ion reduction to Cu as a single substance having an oxidation number of 0 is as follows.

[0342] (C6H 10 O5) n +7H2O →6nCO2+24nH + +24ne -

[0343] Cu 2+ +2e - →Cu

[0344] (C6H 10 O5) n +7H2O+12nCu 2+ →6nCO2+24nH + +12nCu

[0345] Fig.18 (A) is an XRD pattern of the solid product in Evaluation Example 4. Fig.18 (B) is the specific condition of Evaluation Example 4 (the initial Cu 2+ Concentration C Cu 2+ ,0 =1.0mol / L, initial carbon concentration C c,0 =1.0 mol / L) in the case of a solid product (solid residue).

[0346] according to Fig.18 (A) and Fig.18 (B) It can be seen that in the chemical conversion section, Cu with an oxidation number of 2 as an intermediate medium in an oxidized state 2+ The ions are reduced by the biomass as a carbon source to Cu as a single substance having an oxidation number of 0 as an intermediate medium in a reduced state, and the reaction proceeds.

[0347] Fig.19 is a bar graph showing the yield of generated gas in Evaluation Example 4. Fig.19 It can be seen that when the reaction temperature of the chemical conversion section is set to 300°C, Cu 2+ is reduced to Cu, while biomass is oxidized to CO2. 2+ The stoichiometric ratio with CO2 = 2.

[0348] The reaction temperatures of the chemical conversion unit in the above evaluation examples corresponding to the types of solid fuel (carbon source) and medium (intermediate medium) are shown in Table 3. As can be seen from Table 3, low-temperature waste heat of 350° C. or less can be utilized in various combinations of carbon source and intermediate medium.

[0349] [Table 3]

[0350]

[0351] (Evaluation Example 5)

[0352] In Evaluation Example 5, the reaction temperature was set to 250°C and the initial VO 2+ Concentration C VO 2+ ,0=1.0mol / L or 1.8mol / L, initial carbon concentration C c,0 =1.8mol / L, initial H2SO4 concentration C H2SO4,0 =3.0 mol / L, the reaction rate was evaluated.

[0353] Fig. 20 Schematic diagram of the model used in the reaction rate analysis of Evaluation Example 5. Reaction rate r VO 2+ The calculated value is using Fig. 20 The model described is calculated based on the following formula.

[0354] [Formula 1]

[0355]

[0356] k r =0.335L 3 / (mol 2 mol-C min)

[0357] k V3+ =60.9L / mol

[0358] K=0.00129L 2 / mol 2

[0359] ε0=0.15

[0360] Fig.21 The reaction time and VO in Evaluation Example 5 are recorded based on the calculated value of the reaction rate. 2+ The conversion ratio of ions is the conversion, X VO 2+ (Conversion,X VO 2+ ) is a graph showing the relationship between the experimental values ​​in the verification experiment. Fig.21 It can be seen that the experimental value is in good agreement with the calculated value. That is, it is suggested that under the above reaction conditions, in the chemical conversion unit, VO with an oxidation number of 4 as an intermediate medium in an oxidized state 2+The ion is reduced to V with oxidation number 3, which is an intermediate in the reduction state. 3+ ions, and the oxidation reaction of lignite as a carbon source proceeds.

[0361] (Evaluation Example 6)

[0362] In the energy conversion system of Example 2, lignite and VO 2+ The reactor size is calculated for the ion process.

[0363] Fig. 22 This is a schematic diagram of the reactor design of the chemical conversion unit used in Evaluation Example 6. The reactor used is set as an isothermal moving bed reactor. In addition, both the liquid phase and the solid phase are set as extrusion flow. The reactor used is a structure that can react a solid carbon source in a solution containing an intermediate medium in an oxidized state. Z is designed based on the following formula.

[0364] [Formula 2]

[0365]

[0366] Where, the mass velocity of the empty cylinder Gs is: 3.2[kg / (m 2 s)];

[0367] Carbon mass fraction in lignite wc: 0.654 [unitless];

[0368] Molecular weight of carbon Mc: 0.012 [kg / mol];

[0369] Liquid empty cylinder speed uL: 2 [m / s].

[0370] Fig.23 It is a schematic diagram showing the material balance (unit: kmol / s) in Evaluation Example 6 of the energy conversion system of Example 2, the power generation efficiency, and the size of the reactor at that time. Fig.23 In the case of the initial carbon concentration C c,0 =75mol / L, VO 2+ Ion conversion ratio X VO 2+ = 0.2, the reaction temperature is 250°C, and the reactor size is 807m when the operation is carried out in such a way that 100MW of electricity can be obtained with a power generation efficiency of 52.4%. 3 It can be seen that this is about the same size as a boiler with the same power generation capacity and is a size that can be fully realized. Fig.23 In the electrochemical conversion in the electrochemical conversion unit, V 3+ Ion conversion ratio X V 3+ =0.75, efficiency =0.7.

[0371] <(B-2) Demonstration of hydrogen production during power surplus>

[0372] (Evaluation Example 7)

[0373] In Evaluation Example 7, hydrogen production during excess power was verified by an electrolytic reaction (indirect method) using lignite and Cu. Fig.24 Schematic diagram of the energy conversion system used in Evaluation Example 7. In Evaluation Example 7, the electrochemical conversion unit includes an additional power supply component, and in the system of Example 2, a process is performed in which additional power is supplied from the additional power supply component and the electrochemical conversion unit outputs the reduced body (H2) of the reduced material (water) to the outside. The reaction formula of the electrochemical conversion unit in Evaluation Example 7 is as follows.

[0374] Anode: Cu→Cu 2+ +2e - E0=0.337V

[0375] Cathode: 2H + +2e - →H2 E0=0V

[0376] Cu+2H + →Cu 2+ +H2

[0377] ΔH r,0 =64.9KJ / mol

[0378] ΔG r,0 =65.5KJ / mol

[0379] Fig.25 This is a graph showing the relationship between the efficiency of the electrolytic reaction of the energy conversion system used in Evaluation Example 7 and the energy conversion efficiency.

[0380] Energy conversion efficiency

[0381] = Combustion heat of H2 [KJ] / (Combustion heat of lignite after reaction + Amount of electricity actually applied by electrolysis reaction) [KJ]

[0382] The efficiency of the electrolysis reaction

[0383] = The minimum energy required from the thermodynamic point of view [KJ] / The actual amount of electricity applied by the electrolysis reaction [KJ]

[0384] according to Fig.25 It can be seen that when the operation is performed at a general efficiency of 70% for electrochemical reactions, the overall energy conversion efficiency is 90%.

[0385] (Evaluation Example 8)

[0386] In Evaluation Example 8, an example of a hydrogen production process based on an electrolysis reaction using lignite and Cu in the energy conversion system of Example 2 was evaluated by comparison with a conventional hydrogen production process based on an electrolysis reaction of water using a Pt electrode.

[0387] The voltage required to achieve the same current density (same hydrogen generation rate) in each process was measured and is shown in Fig.26 . Fig.26 This is a graph showing the relationship between current density and voltage when hydrogen is produced using the energy conversion system of Example 2 and a conventional method.

[0388] Furthermore, the efficiency of the electrolysis reaction and the energy conversion efficiency at the same current density (same hydrogen generation rate) in each process were calculated and shown in Fig. 27 (A) and Fig. 27 (B). Fig. 27 (A) is a graph showing the relationship between the current density and the efficiency of the electrolysis reaction when hydrogen is produced using the energy conversion system of Example 2 and the conventional method. Fig. 27 (B) is a graph showing the relationship between current density and energy conversion efficiency when hydrogen is produced using the energy conversion system of Example 2 and a conventional method.

[0389] according to Fig.26 and Fig. 27 (B) It can be seen that the energy conversion efficiency of the energy conversion system of Example 2 is about 90%, which is higher than that of the hydrogen production process of the existing method. In addition, it can be seen that the required voltage of the energy conversion system of Example 2 is also lower than that of the hydrogen production process of the existing method.

[0390] In addition, according to Fig. 27 (A) Compared with the conventional hydrogen production process, the energy conversion system of Example 2 has the same efficiency of electrolysis reaction.

[0391] (Evaluation Example 9)

[0392] In Evaluation Example 9, VO as an intermediate medium in the chemical conversion unit was prepared by the same method as in Evaluation Example 5. 2+ Ion concentration and V 3+ Electrolytes with different ion concentrations were prepared, and each electrolyte was brought into contact with the anode and air was supplied to the cathode to confirm the electromotive force and the overall power generation efficiency. The single cell structure in the electrochemical converter was as shown in Table 4 below.

[0393] Fig.28 is the battery voltage (E Cell [V]) and the comprehensive power generation efficiency and VO with an oxidation number of 4 as an intermediate medium in an oxidized state 2+Ion concentration (C VO 2+ ), V with an oxidation number of 3 as an intermediate medium for a metal-containing material in a reduced state 3+ Ion concentration (C V 3+ ) in terms of the total amount of C V 3+ The ratio (C V 3+ / (C VO 2+ +C V 3+ ))'s relationship diagram.

[0394] according to Fig.28 It can be seen that even in C V 3+ / (C VO 2+ +C V 3+ ) is small, that is, the reduction rate is small, sufficient battery voltage and power generation efficiency can be obtained.

[0395] (Evaluation Example 10)

[0396] In Evaluation Example 10, VO2 as an intermediate medium in the chemical conversion unit was prepared in the same manner as in Evaluation Example 9. 2+ Ion concentration and V 3+ The electrolyte solution with the same ion concentration was then brought into contact with the anode and air was supplied to the cathode to generate electricity. The changes in the current value and voltage value during power generation were measured. The structure of the single cell in the electrochemical converter is shown in Table 4 below.

[0397] Fig.29 This is a graph (IV curve) showing the relationship between the current (I) and the voltage (V) during power generation in Evaluation Example 10.

[0398] according to Fig.29 It can be seen that even in VO 2+ ions are not completely reduced to V 3+ In the ion state, there is no problem with the power generation characteristics.

[0399] (Evaluation Example 11)

[0400] In Evaluation Example 11, an example of a hydrogen production process based on an electrolysis reaction using lignite and V as an intermediate medium in the system of Example 2 was evaluated by comparing it with a hydrogen production process of a conventional method based on an electrolysis reaction of water using a Pt electrode. The single cell structure, the medium, and the counter electrode (cathode) supply were set as shown in Table 4 described below.

[0401] The voltage required to achieve the same current density (same hydrogen generation rate) in each process was measured and is shown in Fig.30 . Fig.30 This is a graph showing the relationship between current density and voltage when hydrogen is produced using the system of Example 2 and the conventional method in Evaluation Example 11.

[0402] according to Fig.30 It can be seen that the system of Example 2 has a large current density even at a low voltage, even when V is used as the intermediate medium, compared with the hydrogen production process of the conventional method, and is suitable for high-efficiency hydrogen production.

[0403] Will Figure 26 to Figure 30 Table 4 shows the generated energy forms, single cell structures, media, cathode supplies, applied voltages, and temperatures during power generation or hydrogen production in (Evaluation Examples 8 to 11).

[0404] [Table 4]

[0405]

[0406] Explanation of symbols

[0407] 1: Carbon source

[0408] 2: Intermediate medium in oxidation state

[0409] 3: Intermediate medium in reduced state

[0410] 4: Reduced materials

[0411] 5: Reduced

[0412] 6: Electricity

[0413] 7: Remaining power

[0414] 11: Chemical Conversion Department

[0415] 21: Electrochemical conversion department

[0416] 22: One of the electrodes

[0417] 23: Another electrode

[0418] 24: Power supply unit

[0419] 31: Recycling Department

[0420] 32: Heat exchange unit

[0421] 33: Waste heat supply components

[0422] 34: Heat return piping

[0423] 41: Control Department

[0424] 42: Additional power supply components

Claims

1. A method for generating electricity or producing hydrogen, which is a method for generating electricity or producing hydrogen from a carbon source, and comprises: In the chemical conversion step, a mixture of a solution containing an intermediate medium and a carbon source is mixed in a chemical conversion section. Chemical reaction in the reduced state exceeding the intermediate medium reacting at a temperature of 1000 to 2000 °C to reduce the intermediate medium while oxidizing the carbon source; An electrochemical conversion step, wherein an anode of the battery structure in an electrochemical conversion unit having a battery structure is brought into contact with a solution containing an intermediate medium reduced in the chemical conversion step, or a substrate on which an intermediate medium reduced in the chemical conversion step is precipitated is used as the anode of the battery structure, and a cathode of the battery structure is brought into contact with oxygen or air to generate electricity, or a cathode of the battery structure is brought into contact with water to produce hydrogen; as well as The recycling step returns the solution containing the intermediate medium after the electrochemical conversion step to the mixture.

2. The method for generating electricity or the method for producing hydrogen according to claim 1, wherein: In the chemical conversion step, the intermediate medium in a reduced state is deposited on a substrate, and in the electrochemical conversion step, the substrate on which the intermediate medium is deposited is used as the anode of the battery structure in the electrochemical conversion unit.

3. The method for generating electricity or the method for producing hydrogen according to claim 1 or 2, wherein: The reaction temperature in the chemical conversion step is 350° C. or less.

4. The method for generating electricity or the method for producing hydrogen according to claim 1 or 2, wherein: The intermediate medium contains at least one element of V, Cr, Mn, Fe, Cu, and Zn.

5. The method for generating electricity or the method for producing hydrogen according to claim 1 or 2, wherein: The CO2 generated by the redox reaction in the chemical conversion unit is recovered.

6. An energy conversion system comprising: A chemical conversion section that oxidizes the carbon source and simultaneously reduces the intermediate medium from an oxidized state to a reduced state; as well as The electrochemical conversion unit includes one electrode, another electrode, and a current supply unit connecting the one electrode to the other electrode, wherein the intermediate medium is oxidized from a reduced state to an oxidized state by the one electrode and the reduced material is reduced by the other electrode. In the chemical conversion section, the chemical The chemical state of the intermediate medium exceeds the reduction state The reduction reaction is carried out at a temperature of The electrochemical converter outputs at least one of a reduced product of the reduced material and electric power to the outside. 7 . The energy conversion system according to claim 6 , comprising a plurality of at least one of the chemical conversion unit and the electrochemical conversion unit.

8. The energy conversion system according to claim 6 comprises a plurality of the electrochemical conversion units, a part of the electrochemical conversion units outputs hydrogen as the reduced material to the outside, and another part of the electrochemical conversion units outputs electric power to the outside, and the electric power is used as auxiliary power for outputting the hydrogen to the outside.

9. The energy conversion system according to claim 6, wherein: The CO2 generated by the redox reaction in the chemical conversion unit is recovered.

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