Biomass-based power generation system and power generation method

Abstract

This invention provides an effective method for generating electricity through a process that involves dissolving biomass to produce solid fuel. [Solution] A power generation method using a power generation system having a dissolution reactor, a fuel converter, a carbon dioxide separator, and a power generation cell, comprising: a biomass dissolution step, in which biomass is reacted with a dissolution reaction solution containing vanadium ions in the dissolution reactor to obtain a fuel liquid which is a solution in which cellulose and hemicellulose contained in the biomass are dissolved in the dissolution reaction solution; a fuel conversion step, in which the fuel liquid is brought into contact with a catalyst contained in the fuel converter to oxidize the sugar components contained in the fuel liquid and obtain carbon dioxide and a converted fuel liquid; an anode supply liquid acquisition step, in which the carbon dioxide separator recovers the carbon dioxide contained in the converted fuel liquid and obtains a converted fuel liquid with a reduced carbon dioxide content as an anode supply liquid; and a power generation step, in which the anode supply liquid is supplied to the anode of a power generation cell to generate electricity.

Description

[Technical Field]

[0001] This invention relates to a method for obtaining suitable solid fuel from biomass, a method for effectively utilizing resources discharged during the process of obtaining solid fuel, and systems used in these. [Background technology]

[0002] Japanese Patent Publication No. 2013-14737 describes a method for producing high-calorific value fuel from biomass. However, this method requires high-temperature reactions and results in a low fuel yield. Therefore, a more efficient method for producing solid fuel was desired. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2013-14737 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] This invention aims to provide a method for producing solid fuel by dissolving biomass. Furthermore, this invention aims to provide a method for effectively utilizing resources discharged during the process of obtaining solid fuel, and a system used for such utilization. [Means for solving the problem]

[0005] This invention solves any of the above objectives and is based on findings from examples showing that high-calorific value solid fuel can be produced in high yield by including vanadium ions in a biomass dissolving solution.

[0006] The above problems are solved by the method of the present invention. This method includes a dissolution step in which biomass is reacted with a dissolution reaction solution containing vanadium ions. [Effects of the Invention]

[0007] As demonstrated by the examples, high-calorific value solid fuel can be produced in high yield by dissolving biomass using a vanadium ion solution. Furthermore, the resulting solid fuel contains high-purity lignin. Moreover, this process for producing such solid fuel can be used to generate electricity effectively. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a block diagram showing an example of an apparatus for manufacturing solid fuel. [Figure 2] Figure 2 is a block diagram showing a different example of an apparatus for manufacturing solid fuel, as shown in Figure 1. [Figure 3] Figure 3 is a block diagram illustrating an example of a power generation system configuration. [Figure 4] Figure 4 shows a conceptual diagram of a solid fuel manufacturing apparatus. [Figure 5] Figure 5 shows a conceptual diagram of a power generation system using a solid fuel manufacturing device. [Figure 6] Figure 6 is a photograph that replaces the diagram showing the biomass before the experiment. [Figure 7] Figure 7 is a graph that replaces the diagram showing the temperature profile in the embodiment. [Figure 8] Figure 8 is a photograph that replaces the diagram showing the biomass after the test. [Figure 9] Figure 9 is a graph that replaces the diagram, showing the results of the compositional analysis of the residue and fuel liquid obtained after the test. [Figure 10] Figure 10 is a graph that replaces the diagram showing the IR analysis results of the residue obtained after the test. [Modes for carrying out the invention]

[0009] The following describes a method for producing solid fuel from biomass. This method includes a dissolution step in which biomass is reacted with a dissolution reaction solution containing vanadium ions.

[0010] This method includes a dissolution step and a solid residue recovery step. FIG. 1 is a block diagram showing an example of an apparatus for producing solid fuel. As shown in FIG. 1, this solid fuel production apparatus 1 has a dissolution reactor 5, a fuel surge tank 7, and a water separator 9. The water separator 9 is an optional element. As shown in FIG. 1, the solid fuel production apparatus 1 may have either or both of a raw material input section 13 and a dissolution reaction liquid input section 19. In the example shown in FIG. 1, a filter 11 is present in the dissolution reactor 5. Also, in the example shown in FIG. 1, the dissolution reactor 5 and the fuel surge tank 7 are connected via a connection section 15 so that liquid can be transported.

[0011] Pretreatment step The pretreatment step is an optional step for processing biomass into a state suitable for the reaction in the dissolution step. In the pretreatment step, the biomass may be washed or crushed to an appropriate size so that the biomass can preferably be dissolved in the dissolution step. The pretreatment step may not be provided, or the dissolution step may be performed immediately after the pretreatment step. Biomass is usually an organic resource derived from nature, has the property of being a renewable resource, and may be an animal-derived or plant-derived resource serving as a carbon source. Examples of animal- and plant-derived biomass are wood, wood chips, crop residues, livestock manure, food waste (e.g., tea leaves, beer lees), seaweed, waste oil (e.g., used cooking oil), paper scraps, and cardboard. As biomass, plant-derived biomass is preferred. Plant-derived biomass contains, for example, cellulose, hemicellulose, and lignin. When the biomass is solid biomass, it is preferable to perform the dissolution step before sending it to the fuel converter 25.

[0012] Dissolution step In the dissolution step, the biomass is reacted with a dissolution reaction liquid containing a mediator (vanadium ions). The dissolution reaction liquid preferably contains an acid. Vanadium ions mean ions of vanadium, for example, V 2+ ,V 3+ ,VO 2+ , and VO2+ Any cation containing vanadium, such as those mentioned above, may be used. The vanadium ions contained in the dissolution reaction solution are preferably vanadium ions in an oxidized state, and may be divalent to pentavalent vanadium ions, preferably trivalent to pentavalent vanadium ions, and may also be tetravalent vanadium ions. In other words, it is preferable that the vanadium ions function as an oxidizing agent. The vanadium ions added to the dissolution reaction solution may be obtained by dissolving vanadium pentoxide (V2O5) in dilute sulfuric acid or dilute nitric acid, or by dissolving vanadium(III) chloride salt in hydrochloric acid or nitric acid, or by dissolving vanadium(IV) oxide in an acid. A preferred example of the vanadium ions in the dissolution reaction solution is vanadyl ions (VO 2+ ). Vanadyl ions (VO 2+ ) are vanadium oxide ions containing tetravalent vanadium. Vanadyl ions may be derived from, for example, an aqueous solution of VOSO4, or may be obtained by dissolving vanadium(IV) oxide in an acid. The dissolution reaction solution may be a commercially available one used as appropriate. The dissolution reaction solution preferably further contains an acid. By containing an acid, the hydrolysis reaction of polysaccharides in the biomass can be promoted in the dissolution step. Examples of the acid are phosphoric acid, sulfuric acid, nitric acid, and hydrochloric acid. As the vanadium ions, those after the dissolution step may be added to the dissolution reaction solution. As the vanadium ions, the anode effluent obtained by the electrochemical conversion step described later may be added to the dissolution reaction solution.

[0013] The dissolution reactor 5 is a container part for accommodating the dissolution reaction solution and reacting the raw material with the dissolution reaction solution. The dissolution reactor 5 preferably has a stirrer. Also, the dissolution reactor 5 preferably has elements for solid-liquid separation, such as a filter 11 and a filtration part. The dissolution reactor 5 has, for example, a connection part 15 between the raw material input part 13 and the fuel surge tank 7. In the example shown in FIG. 1, the dissolution reactor 5 has, upstream thereof, a water separator 9 and a dissolution reaction solution input part 19. The raw material input section 13 is an element for introducing raw materials into the dissolution reactor 5. The raw material input section 13 may have a rotary valve to allow biomass to be introduced into the dissolution reactor 5 continuously or in batches. The biomass may be slurried and introduced using a slurry pump. When slurring the biomass, the biomass and the dissolution reaction solution may be mixed. Alternatively, the dissolution reaction solution may be introduced from the raw material input port 13. The connection section 15 to the fuel surge tank 7 is an element for guiding the fuel liquid obtained in the dissolution process to the fuel surge tank 7. An example of the connection section 15 is a conduit. Various elements may be located along the connection section 15. Examples of elements located along the connection section 15 include valves, sensors, and piping for injecting another liquid into the liquid moving through the connection section. The water separator 9 is an optional element for cooling gases such as water vapor generated in the dissolution reactor 5 and releasing some of them outside the system. The water separator 9 may also return some of the water obtained by cooling the gas back to the dissolution reactor 5. The dissolution reaction solution input section 19 is an optional element for introducing the dissolution reaction solution into the dissolution reactor 5. The dissolution reaction solution may be the anode discharge liquid described later. The dissolution reaction solution input section 19 may be used to introduce a liquid containing the dissolution reaction solution, acid, or mediator into the dissolution reactor 5.

[0014] Initially, an aqueous solution of acid may be present in the dissolution reactor 5. After adding the raw materials, the aqueous solution of acid may be stirred to dissolve the raw materials, and then vanadium ions may be added. However, the dissolution reactor 5 may already contain a dissolution reaction solution containing vanadium ions. Acid may be added to this dissolution reaction solution beforehand. The following describes each step based on an example using vanadyl ions and sulfuric acid. However, each step may use other vanadium ions or other acids. Furthermore, the dissolution reaction solution may contain various catalysts or other elements.

[0015] The concentration of vanadium(V) sulfate (VOSO4) (ionic component) added to the dissolution reaction solution may be, for example, 0.01 mol / L or more and 100 mol / L or less, 0.1 mol / L or more and 10 mol / L or less, 0.1 mol / L or more and 5 mol / L or less, or 0.5 mol / L or more and 1.8 mol / L or less. The concentration of sulfuric acid (acid) in the dissolution reaction solution may be, for example, 0.01 mol / L or more and 100 mol / L or less, 0.1 mol / L or more and 10 mol / L or less, 1 mol / L or more and 10 mol / L or less, or 1.8 mol / L or more and 3 mol / L or less. The dissolution reactor 5 preferably has a heating part (not shown). Examples of the liquid temperature of the dissolution reaction solution in the reaction chamber are 50°C or more and 1000°C or less, 50°C or more and 500°C or less, 100°C or more and 300°C or less, or 150°C or more and 250°C or less. The pressure in the dissolution reactor 5 is preferably adjusted to be a pressure equal to or higher than the vapor pressure of the dissolution reaction solution. On the other hand, it is preferable to prevent a situation where the pressure in the dissolution reactor 5 becomes higher than the endurance pressure of the dissolution reactor 5.

[0016] The vapor in the dissolution reactor 5 may be led to the water separator 9 through a conduit. A cooling part exists in the conduit, and the vapor may be introduced into the water separator 9 as a liquid. The biomass is reacted with the dissolution reaction solution, for example, under stirring for 1 minute or more and 1 day or less (it may also be 10 minutes or more and half a day or less, 20 minutes or more and 5 hours or less, or 0.5 hours or more and 4 hours or less). Then, mainly, a reaction occurs in which cellulose and hemicellulose contained in the biomass dissolve in the liquid phase. The dissolved cellulose and hemicellulose dissolve in the liquid phase as sugars. On the other hand, lignin remains almost insoluble in the dissolution reaction solution. Note that a part of the tetravalent vanadyl ion (VO 2+ ) in the dissolution reaction solution is reduced to trivalent vanadium ion (V 3+ ). Vanadyl ion (VO 2+The presence of vanadyl ions (VO2) increases the solubility of cellulose and hemicellulose, as well as the purity of lignin in the residue, as shown in the examples described later. For this reason, for example, when biomass is continuously fed into the dissolution reactor 5, or when new biomass is fed into the dissolution reactor 5 in batch processing, 2+ It is preferable to introduce the source into the dissolution reactor 5. An example of such a vanadyl ion source is the anode effluent described later.

[0017] The filter 11 installed inside the dissolution reactor 5 is an element that prevents biomass residue (solid fuel) from flowing into the connecting section 15. The mesh size of the filter 11 should be appropriate to the size of the substance that passes through it. A hole for connecting to the connecting section 15 is formed in the bottom surface of the dissolution reactor 5, and the filter 11 may be installed so as to cover this hole. Although not shown in the figures, the bottom surface of the dissolution reactor 5 may be flat like a normal chamber, or the area where the filter 11 is installed (for example, the central area of ​​the bottom surface) may have a raised shape (a raised shape) compared to the surrounding area. The height of the raised area should be adjusted as appropriate according to the size of the dissolution reactor 5 and the amount of biomass being introduced. With such a shape, biomass residue (solid fuel) can accumulate around the filter 11, preventing biomass residue from accumulating on the filter 11.

[0018] Solid residue recovery process The solid residue recovery process is a process for recovering the solid residue of biomass after the dissolution process. The dissolution reactor 5 may have a solid-liquid separator such as a filter 11 or a filtration section inside the dissolution reactor 5. The dissolution reactor 5 may have a lid, and by opening the lid, the dissolution reactor 5 can be opened to recover the solid residue of biomass.

[0019] Figure 2 is a block diagram showing a different example of an apparatus for producing solid fuel from Figure 1. In this example, a solid-liquid separator 17 is located outside the chamber of the dissolution reactor 5. Thus, the apparatus 1 may have a solid-liquid separator 17 in addition to the dissolution reactor 5. As shown in Figure 1, a hole for connecting to a connecting part 15 may be provided at the bottom of the dissolution reactor 5, or as shown in Figure 2, a hole for connecting to a connecting part 15 may be provided on the side of the dissolution reactor 5. In the case of Figure 2, the main part of the solid residue may accumulate at the bottom of the dissolution reactor 5, and a portion of the solid residue transmitted to the connecting part 5 may be separated by the solid-liquid separator 17. However, the biomass residue present inside the dissolution reactor 5 may be transmitted to the solid-liquid separator 17 and separated into a solid part and a solution part by the solid-liquid separator 17. Furthermore, as shown in Figure 1, a filter 11 may be provided inside the dissolution reactor 5, and a solid-liquid separator 17 may be provided outside the dissolution reactor 5. The solid-liquid separator 17 may be installed between the fuel surge tank 7 and the dissolution reactor 5, or it may be installed downstream of the fuel surge tank 7.

[0020] When biomass reacts with the dissolution reaction solution, the partially dissolved biomass is separated into residue components and components of biomass dissolved in the dissolution reaction solution. These are separated into residue and components dissolved in the solution by the solid-liquid separator 17. After recovering the residue, a post-treatment process may be performed. The post-treatment process is the final treatment process and is for purifying the product and properly treating the waste. Specifically, after recovering the biomass residue, solid fuel can be obtained by washing and drying it as appropriate. As shown in the examples described later, this residue contains lignin in high purity. Therefore, this apparatus 1 also functions as a (high-purity) lignin production apparatus. The produced lignin can be used as solid fuel, and because it has an aromatic polymer backbone, it can be used as a raw material for phenol derivatives and aromatic chemicals through oxidation, decomposition, catalytic modification, etc. Thus, this apparatus can also be applied as an apparatus for producing lignin as a chemical raw material. The solution separated by filter 11 or solid-liquid separator 17 contains a large amount of reducing sugar components, as well as vanadyl ions (VO2). 2+In addition to ), vanadium ions (V 3+ ) and sulfate ions are included. This solution is introduced into the fuel surge tank 7 as appropriate. These vanadium ions are used in the power generation system described later and may be converted into a solution containing vanadyl ions as anode discharge liquid.

[0021] Figure 3 is a block diagram illustrating an example of the configuration of a power generation system. As shown in Figure 3, the power generation system 21 includes a dissolution reactor 5, a fuel converter 25, a heat exchanger 27, (a carbon dioxide separator 29), and a power generation cell 31. The power generation cell 31 is the part that undergoes an electrochemical reaction. The power generation system 21 is a device for obtaining electricity using the solid fuel manufacturing apparatus 1 described above. However, the example shown in Figure 3 can also function as a battery system, so it may be a system that is not intended to manufacture solid fuel. Solid biomass may be introduced into the dissolution reactor 5 in the power generation system 21 shown in Figure 3. The fuel surge tank 7 contains a liquid containing vanadium ions and sulfate ions. The fuel surge tank 7 is an element for holding the dissolved reaction liquid (fuel liquid) after the reaction has taken place in the dissolution reactor 5 and the residue has been removed. This fuel liquid contains dissolved biomass, which is a biomass-derived component that has dissolved in the liquid phase after passing through the dissolution reactor. This fuel liquid in the fuel surge tank 7 is used as a reducing agent in the electrochemical reaction described later. However, the fuel surge tank 7 does not have to be present in the power generation system 21.

[0022] Fuel converter 25 The fuel converter 25 is an element for oxidizing the sugar components contained in the fuel liquid into carbon dioxide and water. The fuel liquid containing dissolved biomass along with the dissolution reaction liquid is sent to the fuel converter 25 from the dissolution reactor 5 via the connecting part 15. Vanadyl ions (VO2) are added to the fuel liquid. 2+ If ) is included, the fuel converter 25 contains vanadium ions (V 3+) is reduced to ). This process is also called the chemical energy conversion process. In the fuel converter 25, the biomass dissolved in the fuel liquid may be oxidized. The liquid containing the mediator (vanadyl ion) reduced by the fuel converter 25 is transmitted to the next heat exchanger 27 or power generation cell 31, for example, via a connecting pipe. A mediator refers to a chemical species that mediates the exchange of electrons in an oxidation-reduction reaction.

[0023] The fuel converter 25 may, for example, have a mechanism (catalyst layer) in which a solid catalyst is packed into a tubular container. The solid catalyst should be capable of decomposing sugar into carbon dioxide and water. Examples of such solid catalysts include metal catalysts, metal oxide catalysts, mixed oxide catalysts, photocatalysts, peroxides, and radical generation catalysts. Examples of metal catalysts include catalysts supported with platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), gold (Au), silver (Ag), Pt, or Pd. Examples of metal oxide catalysts include copper oxide (CuO, Cu2O), manganese oxide (MnO2), iron oxide (Fe2O3, Fe3O4), cobalt oxide (Co3O4), chromium oxide (Cr2O3), nickel oxide (NiO), cerium oxide (CeO2), and vanadium oxide (V2O5). Examples of mixed oxide catalysts include perovskite oxides (e.g., LaMnO3 and LaCoO3), spinel oxides (e.g., MgAl2O4), zeolite-supported metal catalysts (e.g., Pt / ZSM-5), and ceria-zirconia catalysts (CeO2-ZrO2). Examples of photocatalysts include titanium dioxide (TiO2), nitrogen-doped titanium dioxide, ZnO (zinc oxide), CdS (cadmium sulfide), graphite carbon nitride, and BiVO4 (bismuth vanadate). Examples of peroxide and radical-generating catalysts include Fenton reaction catalysts. These can be used individually or in combination of two or more. These solid catalysts may also be used supported on some kind of carrier.

[0024] The fuel converter 25 is preferably adjusted to an appropriate temperature depending on the type of catalyst. The temperature inside the fuel converter is 50°C to 1000°C, may be 50°C to 500°C, 100°C to 300°C, or 150°C to 250°C. The reaction may be allowed to proceed in the fuel converter for 1 minute to 1 day. The reaction time may be 10 minutes to half a day, 20 minutes to 5 hours, or 0.5 hours to 4 hours. Inside the fuel converter, it is preferable to adjust the temperature to be above the vapor pressure of the solution so that the solution does not vaporize. Therefore, carbon dioxide generated by the oxidation of sugar may be dissolved in the solution and may exist as carbonate ions, carbonates, or carbon dioxide.

[0025] heat exchanger 27 The heat exchanger 27 is an element for exchanging heat between the high-temperature solution (converted fuel liquid) output from the fuel converter 25 and a low-temperature fluid (for example, the low-temperature anode discharge liquid output from the power generation cell). The heat exchanger 27 is an optional element. The cold liquid may be fuel liquid, cooling water supplied from outside the system, or cooling air. For example, the solution (dissolution reaction liquid) output from the fuel converter 25 may be cooled to below 100°C by heat exchange in the heat exchanger 27 and further cooling in the cooling section.

[0026] carbon dioxide separator 29 In the carbon dioxide separator 29, a portion of the carbon dioxide in the converted fuel liquid, which is the solution output from the fuel converter 25, remains dissolved, while the rest forms bubbles and is sent to the carbon dioxide separator 29 in a gas-liquid mixed phase state. The carbon dioxide separator 29 is an optional element. The carbon dioxide is separated by the carbon dioxide separator 29 and can be recovered as high-purity carbon dioxide. Preferably, the carbon dioxide separator 29 is equipped with a control valve in the gas phase of the carbon dioxide separator 29 to control the pressure in the gas phase so that it is at a predetermined gauge pressure (e.g., 4 MPaG or less). The converted fuel liquid from which most of the carbon dioxide has been removed by the carbon dioxide separator 29 contains the dissolved reaction liquid and reduced vanadium ions. The carbon dioxide separator 29 may also have a condenser and a water separator. The water separated in the water separator may be returned to the dissolution reactor 5.

[0027] Power generation cell 31 The power generation cell 31 includes a housing for the electrolyte, an anode and a cathode installed within the housing, and an ion exchange membrane. The electrolyte refers to a solution that allows ions to move within the power generation cell and enables oxidation-reduction reactions. An example of an electrolyte is a solution containing 1.8 M VOSO4 (vanadium electrolyte) and 3 M H2SO4 (supporting electrolyte). The structure and mechanism of the power generation cell 31 are well known. In the power generation cell, for example, the converted fuel liquid obtained in each of the above steps is supplied to the anode side of the power generation cell as the anode supply liquid, oxidizing the vanadium ions contained in the anode supply liquid to obtain an anode discharge liquid, which is a liquid containing the oxidized vanadium ions. This step is also called the electrochemical conversion step. The electrochemical conversion step has, for example, the following two patterns.

[0028] (1) The converted fuel liquid (anode supply liquid), from which carbon dioxide has been removed by the carbon dioxide separator 29, is supplied to the anode side of the power generation cell using the operating pressure of the carbon dioxide separator 29. A solution containing vanadium ions or air is supplied to the cathode side of the power generation cell. As a result, the vanadium ions on the anode side are oxidized, and the vanadium ions on the cathode side or oxygen in the air are reduced. Electricity can be generated by the electromotive force produced by this oxidation-reduction reaction. For example, trivalent vanadium is supplied to the anode side and pentavalent vanadium is supplied to the cathode side, and they are all or partially oxidized and reduced to tetravalent vanadium, respectively.

[0029] (2) The converted fuel liquid (anode supply liquid), from which most of the carbon dioxide has been removed by the carbon dioxide separator 29, is sent to the anode side of the hydrogen production cell using the operating pressure of the carbon dioxide separator 29. Water is supplied to the cathode side of the hydrogen production cell and charged. Vanadium ions on the anode side are oxidized, and the water on the cathode side is reduced to hydrogen. For example, if trivalent vanadium is supplied to the anode side and water is supplied to the cathode side and charged, the trivalent vanadium is oxidized to tetravalent vanadium and the water is reduced to hydrogen.

[0030] In all of the above patterns, the vanadium ions supplied to the anode are oxidized, for example, vanadyl ions (VO2). 2+ ) is included. The anode discharge liquid obtained in this manner may be heated as appropriate via the heat exchanger 27 and added to the fuel converter 25. Alternatively, the anode discharge liquid may be added to the dissolution reactor 5.

[0031] The power generation method described in this specification may include a solid residue recovery step, a chemical energy conversion step, and an electrochemical conversion step. The method for producing solid fuel described above may further include a chemical energy conversion step and an electrochemical conversion step after the solid residue recovery step, or it may further include a vanadium oxide ion addition step after the electrochemical conversion step. The solid residue recovery process is the process of recovering solid residue after the dissolution process. The chemical energy conversion process is a process in which biomass-derived components (e.g., reducing sugar components) contained in the fuel liquid after the solid residue recovery process are oxidized to carbon dioxide to obtain the converted fuel liquid. In other words, the chemical energy conversion process is a process for converting chemical energy by using chemical reactions to change the raw material (solvent) into the target compound (fuel liquid). The electrochemical conversion process is a process that uses electrochemical reactions to oxidize and reduce substances and extract electrical energy. Specifically, the electrochemical conversion process involves supplying the converted fuel liquid (anode supply liquid) after the chemical energy conversion process to the anode side of the power generation cell, oxidizing the vanadium ions contained in the anode supply liquid, and obtaining anode discharge liquid, which is a liquid containing the oxidized vanadium ions. The vanadium oxide ion addition step involves adding the anode effluent to either the dissolution reaction solution in the dissolution step or the fuel liquid in the chemical energy conversion step, or both.

[0032] Another aspect of this invention relates to a method for producing lignin from biomass. This method can be described by substituting lignin for the solid fuel mentioned above. As will be shown in the examples described later, the residue obtained by this method has a high purity of lignin. [Examples]

[0033] Identification of vanadium ions Vanadium ions can be analyzed using known methods. For example, the presence of these ions can be detected by analyzing the ultraviolet absorption spectrum of a solution. For instance, vanadyl ions show absorption around 450-600 nm. After confirming the presence of vanadium ions, the valence of the ions in the solution can be evaluated by adding an oxidizing or reducing agent and observing the color change.

[0034] [Examples 1, 2 and Comparative Examples] Figure 4 shows a conceptual diagram of a solid fuel production apparatus in an embodiment. The system includes a dissolution reactor for carrying out the reaction; a biomass inlet located upstream of the dissolution reactor for introducing biomass into the dissolution reactor; a dissolution reaction liquid injection section for injecting the dissolution reaction liquid into the dissolution reactor, which has piping, a heater and a pump for liquid delivery; and a connecting section located downstream of the dissolution reactor, which has a cooler and a back pressure valve. Furthermore, covers and filters are installed at the connections to various pipes of the fuel converter to prevent biomass from flowing into the pipes. Figure 5 shows a conceptual diagram of a power generation system using the solid fuel production apparatus.

[0035] A cylindrical container was filled with 500 mg of dry biomass (dried cedar) and sandwiched between liquid-permeable filters. The biomass was at room temperature and had a moisture content of 30-60%. This is shown in Figure 6. Figure 6 is a photograph that replaces the diagram showing the biomass before the test. The cylindrical container filled with biomass was placed in the dissolution reactor. The dissolution reaction solution at room temperature, with the concentrations shown in Table 1, was pumped at a rate of 1 mL / min, heated to the test temperature in a heater, and then added to the dissolution reactor from the dissolution reaction solution injection port. More specifically, the sulfuric acid concentration of the vanadium sulfate oxide aqueous solution used in the experiment was 1-2 mol / L, and the acidity was pH -0.3 to -0.6. The pump was set to 1 mL / min at room temperature. The vanadium sulfate oxide aqueous solution flowing through the piping was heated to 150°C in Example 1 and Comparative Example 1, and to 200°C in Example 2, and the reaction was carried out for about 30 minutes. The piping (or hoses) used were resistant to vanadium sulfate oxide. An aqueous solution of vanadium sulfate oxide was injected into the dissolution reactor via a lid. A (first) filter was installed inside the dissolution reactor. This filter was used to prevent biomass in the dissolution reactor from flowing into the piping. The pressure inside the dissolution reactor was 2 MPa. The material fed into the dissolution reactor was plant biomass. A (second) filter was also installed at the biomass inlet, and a lid was provided. Piping was installed via the lid. In this embodiment, a cooler was provided to cool the liquid flowing through the piping.

[0036] In the example, the system temperature was controlled according to the temperature profile shown in Figure 7. After maintaining the temperature at each condition shown in Table 1 for the required residence time, the system temperature was lowered. The biomass after the test is shown in Figure 8. Figure 8 is a photograph instead of a diagram showing the biomass after the test. After the test, filtration was performed to separate the residue from the solution.

[0037] Compositional analysis and IR analysis were performed on the residues and solutions obtained after the test. Figure 9 is a graph that replaces the diagram showing the results of the compositional analysis of the residues and solutions obtained after the test. The graph shows, from left to right, raw material, Example 1 (residue), Example 2 (residue), Comparative Example 1 (residue), lignin (dealkalized), Example 1 (solution), Example 2 (solution), cellulose, hemicellulose, and monosaccharides. Figure 10 is a graph that replaces the diagram showing the results of the IR analysis of the residues obtained after the test. The horizontal axis shows wavenumber, and the vertical axis shows absorption. The graph shows, from bottom to top, Example 1, Example 2, Comparative Example 1, and lignin (dealkalized).

[0038] Table 1 shows the residue yield, calorific value, and heat recovered from the biomass. The Steuer formula was used to calculate the calorific value. The Steuer equation is used to determine the amount of heat generated from the elemental composition (carbon C, hydrogen H, sulfur S, oxygen O [%]). Assuming that the oxygen in the combustible material is CO and the other half is bonded in the form of H2O, the amount of heat generated is calculated using the following equation. Hh=339.4(C-(3 / 8)O)+238.8×(3 / 8)O+1435.1(HO / 16)+94.3·S

[0039] [Table 1]

[0040] Consideration Figure 9 shows that the residues (solid fuels) obtained in Examples 1 and 2 approached the elemental composition of pure lignin, and the solutions (dissolved biomass) obtained in Examples 1 and 2 approached the elemental composition of monosaccharides. This trend was stronger in Example 1 than in Example 2. Figure 9 also shows that the amount of cellulose contained in the biomass raw material decreased in the examples. Furthermore, Figure 10 shows that the residues (solid fuels) obtained in Examples 1 and 2 exhibited absorption spectra close to those of pure lignin. Therefore, this method can be said to function as a method for producing high-purity lignin. Comparing Example 2 with Comparative Example 1 in Table 1, it can be seen that including vanadyl ions in the dissolution reaction solution improves the residue yield by more than 20% and the recovered heat by about 10%. Thus, it has been shown that including vanadyl ions in the dissolution reaction solution improves the yield of solid fuel.

[0041] In this example, dried cedar was used as the biomass. The effect of this example is thought to be based on the function of vanadyl ions as an oxidizing agent. Therefore, it is believed that any biomass that serves as a carbon source will produce the same effect as in this example. Furthermore, any oxidizing agent that contributes to biomass may produce the same effects as in the example, so it is thought that including ions that can function as oxidizing agents, such as vanadium ions, in the reaction solution can improve the yield of solid fuel. For this reason, the concentration of these ions and their ratio to the acid are not limited to this example and can be adjusted as appropriate (for example, the concentration of vanadium ions in the dissolution reaction solution may be 0.01 mol / L or more and 100 mol / L or less). Although the reaction system temperature may be room temperature for the reaction to take place, it is preferable to carry out the reaction at a relatively high temperature (e.g., 50°C to 400°C) and high pressure (e.g., 1.5 atmospheres to 100 atmospheres) in order to improve the yield of solid fuel. In addition, although sulfuric acid was used as the acid component in the example, it is thought that any component that can dissolve biomass and form a salt with vanadium can be preferably used in this system. [Industrial applicability]

[0042] This invention can preferably produce solid fuel from biomass, and therefore can be used in fields such as solid fuels and the utilization of biomass-derived chemical raw materials. [Explanation of symbols]

[0043] 1. Solid fuel manufacturing apparatus 5. Dissolution reactor 7. Fuel surge tank 9 Water separator 13 Raw material input section 15 Connecting part 19 Dissolution reaction solution input section 21 Power generation system 25 Fuel Converter 27 Heat exchanger 29 Carbon dioxide separator 31 power generation cells

Claims

1. A method for generating electricity using a power generation system having a dissolution reactor (5), a fuel converter (25), a carbon dioxide separator (29), and a power generation cell (31), The biomass dissolution step is a step in which biomass is reacted in the dissolution reactor (5) with a dissolution reaction solution containing vanadium ions to obtain a fuel liquid which is a solution in which components contained in the biomass are dissolved in the dissolution reaction solution, A fuel conversion step is a step of bringing the fuel liquid into contact with a catalyst contained in the fuel converter (25) to oxidize the components contained in the fuel liquid and obtain carbon dioxide and converted fuel liquid. The carbon dioxide separator (29) separates or removes at least a portion of the carbon dioxide contained in the converted fuel liquid, and obtains the converted fuel liquid with a reduced carbon dioxide content as an anode supply liquid, in the anode supply liquid acquisition step, A method comprising a power generation step, which is the step of supplying the anode supply liquid to the anode of the power generation cell (31) and generating electricity.

2. A power generation method according to claim 1, The power generation process includes an anode discharge liquid acquisition step, which is a step of oxidizing the vanadium ions contained in the anode supply liquid and obtaining an anode discharge liquid which is a liquid containing the oxidized vanadium ions. A method further comprising an anode discharge supply step, which is a step of supplying the anode discharge to the dissolution reactor (5).

3. A power generation method according to claim 1, The method involves the dissolution reaction solution containing vanadium ions in an amount of 0.01 mol / L to 100 mol / L and sulfuric acid in an amount of 0.01 mol / L to 100 mol / L.

4. A method for generating electricity according to claim 1, wherein the vanadium ion includes a vanadyl ion.

5. A power generation method according to claim 2, The power generation system further includes a heat exchanger (27), A method further comprising a heat exchange step, which is a step of performing heat exchange between the converted fuel liquid and the anode discharge liquid.

6. A power generation method according to claim 3, The biomass dissolution step further includes a step of obtaining a solid residue of the biomass containing lignin contained in the biomass, A method further comprising a biomass solid residue recovery step, which is a step of recovering the solid residue of the biomass.

7. A power generation method according to claim 6, The fuel liquid contains cellulose and hemicellulose contained in the biomass, The method wherein the solid residue of the biomass contains lignin contained in the biomass.

8. A power generation system comprising a dissolution reactor (5), a fuel converter (25), a carbon dioxide separator (29), and a power generation cell (31), The dissolution reactor (5) is configured to contain a dissolution reaction solution containing vanadium ions, react biomass with the dissolution reaction solution, and obtain a fuel liquid which is a solution in which components contained in the biomass are dissolved in the dissolution reaction solution. The fuel converter (25) has a catalyst, and the catalyst is configured to oxidize the components contained in the fuel liquid by contacting it with the fuel liquid to obtain carbon dioxide and converted fuel liquid. The carbon dioxide separator (29) is configured to separate or remove at least a portion of the carbon dioxide contained in the converted fuel liquid, and to obtain the converted fuel liquid with a reduced carbon dioxide content as the anode feed liquid. The power generation cell (31) is configured to generate electricity using the anode supply liquid when the anode supply liquid is supplied to the anode of the power generation cell (31). Power generation system.

9. A power generation system according to claim 8, The power generation cell (31) is configured to oxidize the vanadium ions contained in the anode supply liquid and to discharge the anode discharge liquid, which is a liquid containing the oxidized vanadium ions. A power generation system further comprising piping for supplying the anode discharge liquid to the dissolution reactor (5).

10. A power generation system according to claim 8, The fuel liquid contains cellulose and hemicellulose contained in the biomass, The aforementioned dissolution reaction solution contains vanadium ions in an amount of 0.01 mol / L to 100 mol / L and sulfuric acid in an amount of 0.01 mol / L to 100 mol / L. The power generation system further includes a solid residue recovery unit for recovering the solid residue of the biomass containing lignin contained in the biomass, wherein the dissolution reactor (5) is a dissolution reactor (5).

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