Method for producing modified combustion ash, method for modifying woody biomass and / or its combustion ash, method for producing low-potassium combustion ash, and method for converting it into a cement resource

Abstract

To provide a modified combustion ash manufacturing method that can manufacture modified combustion ash, in which a proportion of water-soluble potassium amount is increased, from woody biomass and / or combustion ash thereof.SOLUTION: Disclosed is a modified combustion ash manufacturing method. The manufacturing method comprises: a heating step of heating woody biomass and / or combustion ash thereof at 700 to 1100°C in an atmosphere of gas containing hydrogen chloride; and a recovery step of recovering fly ash discharged together with the gas containing hydrogen chloride in the heating step. A molar ratio (K / Cl) of a potassium amount in woody biomass and / or combustion ash thereof to a chlorine amount in the gas containing hydrogen chloride is 0.01 to 1.40.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing reformed combustion ash, a method for reforming woody biomass and / or its combustion ash, a method for producing low-potassium combustion ash, and a method for converting it into a cement resource. [Background technology]

[0002] In recent years, from the perspective of preventing global warming, attention has been focused on systems that generate electricity by burning woody biomass, which is considered carbon-neutral, in a boiler. In addition, with the support of the Feed-in Tariff Scheme (FIT) for renewable energy, the number of certified power generation facilities using woody biomass is on the rise. However, this has also raised concerns about the increase in the amount of ash (woody biomass combustion ash) generated by burning woody biomass. There are few effective ways to utilize this woody biomass combustion ash, and the reality is that much of it is disposed of in landfills, so there is a desire for a stable use of woody biomass combustion ash.

[0003] One of the uses of woody biomass combustion ash is being considered as fertilizer. The potassium and silica components in woody biomass combustion ash are thought to be useful as fertilizer components, and for example, Patent Document 1 discloses a fertilizer containing woody biomass combustion ash.

[0004] Another effective use of wood biomass combustion ash is as a raw material for cement clinker. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-85319 Summary of the Invention [Problem to be solved by the invention]

[0006] The potassium component in woody biomass combustion ash is an effective component for fertilizer, but in most woody biomass combustion ash, the potassium component exists as sparingly soluble potassium. This sparingly soluble potassium is thought to be in a state where potassium is incorporated into the aluminosilicate (crystalline) structure, and exists in a stable state, making it difficult to utilize the potassium component. Therefore, there is a need to convert the potassium component in woody biomass combustion ash into water-soluble potassium.

[0007] Therefore, the main object of the present invention is to provide a method for producing reformed combustion ash that can produce reformed combustion ash having an increased proportion of water-soluble potassium from wood biomass and / or its combustion ash. [Means for solving the problem]

[0008] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they discovered that woody biomass and / or its combustion ash can be efficiently reformed into reformed combustion ash having a high proportion of water-soluble potassium even in fly ash recovery, which has a short residence time, by heating the woody biomass and / or its combustion ash in an atmosphere of gas containing hydrogen chloride, and thus completed the present invention.

[0009] One aspect of the present invention relates to a method for producing reformed combustion ash from woody biomass and / or its combustion ash, producing reformed combustion ash with an increased proportion of water-soluble potassium. The production method includes a heating step of heating woody biomass and / or its combustion ash at 700 to 1100°C in a gas atmosphere containing hydrogen chloride, and a recovery step of recovering fly ash discharged together with the gas containing hydrogen chloride in the heating step. The molar ratio (K / Cl) of the amount of potassium in the woody biomass and / or its combustion ash to the amount of chlorine in the gas containing hydrogen chloride is 0.01 to 1.40. Woody biomass is converted into woody biomass combustion ash by combustion. Woody biomass combustion ash may have an aluminosilicate structure composed of silicon and aluminum. According to this production method, by heating in a gas atmosphere containing hydrogen chloride, sparingly soluble potassium, such as that incorporated in the aluminosilicate (crystalline) structure of the woody biomass combustion ash, is converted into water-soluble potassium, thereby obtaining reformed combustion ash. The hydrogen chloride may be hydrogen chloride generated by burning chlorine-containing plastics.

[0010] The method for producing reformed combustion ash involves recovering fly ash emitted during the heating process along with gas containing hydrogen chloride. If the woody biomass combustion ash is to be recovered as bottom ash or bottom furnace ash after being reformed into water-soluble potassium, pretreatment such as granulation is required before reforming, which may increase costs. Furthermore, if the woody biomass combustion ash is to be recovered as bottom ash or bottom furnace ash without pretreatment such as granulation, the gas flow rate must be reduced to prevent scattering. In this case, the hydrogen chloride concentration in the gas must be increased to reform the woody biomass and / or its combustion ash. However, the use of high concentrations of hydrogen chloride may cause equipment corrosion problems. Therefore, the method for producing reformed combustion ash uses low concentrations of hydrogen chloride, which reduces costs and inhibits equipment corrosion compared to recovering bottom ash or bottom furnace ash.

[0011] The amount of water-soluble potassium (K2O) in the reformed combustion ash may be 1.0 to 10.0 mass %.

[0012] When the heating step is a step of heating woody biomass and a chlorine-containing plastic, the proportion of the chlorine-containing plastic may be 1 to 30 parts by mass per 100 parts by mass of woody biomass. When the heating step is a step of heating woody biomass combustion ash and a chlorine-containing plastic, the proportion of the chlorine-containing plastic may be 20 to 3,000 parts by mass per 100 parts by mass of woody biomass combustion ash. The amount of chlorine in the chlorine-containing plastic may be 0.5 to 20% by mass.

[0013] The flow rate of the gas containing hydrogen chloride discharged in the heating step may be 2 to 20 m / s.

[0014] Another aspect of the present invention relates to a method for reforming woody biomass and / or its combustion ash, which reforms woody biomass and / or its combustion ash into reformed combustion ash having an increased proportion of water-soluble potassium. The reforming method includes a heating step of heating the woody biomass and / or its combustion ash at 700 to 1100°C in an atmosphere of a gas containing hydrogen chloride, and a recovery step of recovering fly ash discharged together with the gas containing hydrogen chloride in the heating step. The molar ratio of the amount of potassium in the woody biomass and / or its combustion ash to the amount of chlorine in the gas containing hydrogen chloride is 0.01 to 1.40.

[0015] Another aspect of the present invention relates to a method for producing low-potassium combustion ash, which produces low-potassium combustion ash having a reduced potassium content from reformed combustion ash produced by the above-mentioned production method. The production method includes a washing step of washing the reformed combustion ash with water to remove soluble components.

[0016] Another aspect of the present invention relates to a method for recycling low-potassium combustion ash into a cement resource, in which the low-potassium combustion ash produced by the above-mentioned production method is used as a cement raw material. [Effects of the Invention]

[0017] According to the present invention, there is provided a method for producing reformed combustion ash, which is capable of producing reformed combustion ash having an increased proportion of water-soluble potassium from woody biomass and / or its combustion ash. Furthermore, according to the present invention, there is provided a method for reforming woody biomass and / or its combustion ash, which reforms woody biomass and / or its combustion ash into reformed combustion ash having an increased proportion of water-soluble potassium. Furthermore, according to the present invention, there is provided a method for producing low-potassium combustion ash, which produces low-potassium combustion ash from reformed combustion ash. Furthermore, according to the present invention, there is provided a method for converting reformed combustion ash using low-potassium combustion ash into a cement resource. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing one embodiment of a production facility for reformed combustion ash. [Figure 2] FIG. 2 is a schematic diagram showing another embodiment of the reformed combustion ash production equipment. [Figure 3] FIG. 3 is a schematic diagram showing the reaction apparatus used in the reference examples. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0020] [Manufacturing method of reformed combustion ash] A method for producing reformed combustion ash according to one embodiment is for obtaining reformed combustion ash having an increased proportion of water-soluble potassium from woody biomass and / or its combustion ash. The production method of this embodiment includes at least a heating step and a recovery step.

[0021] The heating step and the recovery step use or generate a gas containing hydrogen chloride, and therefore are usually carried out in a reaction system that allows gas flow and does not leak the gas containing hydrogen chloride.

[0022] Fig. 1 is a schematic diagram showing one embodiment of a manufacturing facility for reformed combustion ash. The manufacturing facility for reformed combustion ash shown in Fig. 1 includes a combustion furnace for carrying out a heating step of heating woody biomass and / or its combustion ash, and a dust collector for carrying out a recovery step of recovering fly ash discharged from the combustion furnace together with a gas containing hydrogen chloride. The combustion furnace has an inlet pipe for introducing the gas containing hydrogen chloride.

[0023] By introducing a gas containing hydrogen chloride into the combustion furnace, the reaction system can be made into an atmosphere of the gas containing hydrogen chloride. The combustion furnace can be appropriately selected depending on the amount of woody biomass and / or its combustion ash to be treated. Examples of combustion furnaces include rotary kiln furnaces, fluidized bed furnaces, circulating fluidized bed furnaces, and stoker furnaces.

[0024] The fly ash collected in the dust collector may be modified combustion ash with an increased proportion of water-soluble potassium. Examples of the dust collector include a cyclone, a bag filter, an electric dust collector, and a spray-type wet dust collector.

[0025] Figure 2 is a schematic diagram showing another embodiment of the equipment for producing reformed combustion ash. The difference from the equipment for producing reformed combustion ash shown in Figure 1 is that hydrogen chloride is generated by heating chlorine-containing plastics, rather than by introducing a gas containing hydrogen chloride. By heating the chlorine-containing plastics in the combustion furnace, the reaction system can be made into an atmosphere of gas containing hydrogen chloride.

[0026] The reformed combustion ash production equipment shown in Figures 1 and 2 can be applied to a system that burns woody biomass as fuel in a boiler to generate electricity. In such a system, reformed combustion ash can be produced in addition to energy production.

[0027] Each step in the method for producing reformed combustion ash will be described in detail below.

[0028] <Heating process> This step involves heating woody biomass and / or its combustion ash at 700 to 1100°C in an atmosphere of gas containing hydrogen chloride.

[0029] Woody biomass refers to wood resources such as forest residues, sawmill residues, construction waste, palm kernel shells, herbaceous plants, and agricultural residues.When using woody biomass for power generation, it is burned in combustion devices such as fluidized bed furnaces, stoker furnaces, and kiln furnaces, and the resulting thermal energy is used.

[0030] Woody biomass combustion ash refers to ash generated when woody biomass is burned, and is a concept that includes bottom ash that accumulates at the bottom of the combustion device and fly ash that is collected by a dust collector. When burning woody biomass, combustible materials other than woody biomass, such as general waste, and fossil fuels such as coal and heavy oil, may also be burned together, but the proportion of woody biomass is preferably 50% by mass or more based on the total amount of materials to be burned.

[0031] The main elements in woody biomass combustion ash are silicon and aluminum, which form the aluminosilicate structure, and phosphorus and potassium, which are plant nutrients. Most of the potassium in woody biomass combustion ash is thought to be incorporated into the aluminosilicate (crystalline) structure and exists in a water-insoluble state.

[0032] In this step, woody biomass and / or its combustion ash may be introduced into a reaction system heated to 700 to 1100°C in an atmosphere of gas containing hydrogen chloride, and then heated. Alternatively, woody biomass and / or its combustion ash may be introduced into a reaction system heated to 700 to 1100°C in an atmosphere other than that of gas containing hydrogen chloride, and then heated by introducing a gas containing hydrogen chloride.

[0033] It is believed that by heating woody biomass and / or its combustion ash in an atmosphere of gas containing hydrogen chloride, the woody biomass immediately burns and is converted into woody biomass combustion ash. In dry woody biomass, the amount of woody biomass combustion ash in the woody biomass is typically 1 to 5 parts by mass per 100 parts by mass of woody biomass. On the other hand, in woody biomass combustion ash (including woody biomass converted into woody biomass combustion ash), heating in an atmosphere of gas containing hydrogen chloride is thought to cause a reaction represented by the following formula (1) to proceed, converting potassium (KO) in the woody biomass combustion ash into water-soluble potassium chloride (KCl), thereby increasing the proportion of water-soluble potassium. K2O+2HCl→2KCl+H2O (1)

[0034] The average volume concentration of hydrogen chloride in the hydrogen chloride-containing gas is preferably 0.005 to 10% by volume, since this allows stable reforming of woody biomass and / or its combustion ash. The average volume concentration of hydrogen chloride is more preferably 0.01 to 5% by volume, and even more preferably 0.1 to 2% by volume. The average volume concentration of hydrogen chloride can be determined, for example, by installing a hydrogen chloride concentration meter in the reactor and tracking changes in the hydrogen chloride concentration. When using a gas containing a predetermined hydrogen chloride concentration that has been prepared in advance, the average volume concentration of hydrogen chloride can be the predetermined concentration of hydrogen chloride in the prepared gas. The average volume concentration of hydrogen chloride can be adjusted, for example, by varying the flow rates of introduced air, nitrogen, etc. When using hydrogen chloride generated by burning chlorine-containing plastics, the average volume concentration of hydrogen chloride can be adjusted by varying the amount of chlorine-containing plastic used, the chlorine content of the chlorine-containing plastic, the amount of introduced air, etc.

[0035] The molar ratio (K / Cl) of the amount of potassium (amount of potassium per unit time) in woody biomass and / or its combustion ash to the amount of chlorine (amount of chlorine per unit time) in the gas containing hydrogen chloride (molar amount of potassium (molar amount of potassium per unit time) / molar amount of chlorine (molar amount of chlorine per unit time)) is 0.01 to 1.40, since woody biomass and / or its combustion ash can be stably modified. The amount of potassium in woody biomass and / or its combustion ash can be measured, for example, in accordance with JIS R 5202:2010 "Methods for Chemical Analysis of Cement." The amount of chlorine in the gas containing hydrogen chloride can be determined, for example, by installing a concentration meter compatible with hydrogen chloride in a reactor to measure the concentration of hydrogen chloride, and then calculating the amount of chlorine based on the concentration. When a chlorine-containing plastic is heated together with woody biomass and / or its combustion ash in a reaction system for heating the woody biomass and / or its combustion ash to generate hydrogen chloride, the amount of chlorine in the chlorine-containing plastic may be considered to be the amount of chlorine in the hydrogen chloride-containing gas. However, if the chlorine-containing plastic contains a component that reacts with chlorine, such as calcium carbonate, the amount of hydrogen chloride generated tends to be low. Therefore, it is desirable to measure the concentration of hydrogen chloride actually generated and calculate the amount of chlorine based on that concentration. The molar ratio is preferably 0.05 to 1.00, more preferably 0.06 to 0.20.

[0036] The hydrogen chloride in the hydrogen chloride-containing gas can be a general industrial gas or a reaction gas used in general chemistry experiments (for example, a gas generated by dropping concentrated hydrochloric acid into concentrated sulfuric acid).

[0037] The hydrogen chloride in the hydrogen chloride-containing gas may be hydrogen chloride generated by burning chlorine-containing plastics in an oxidizing atmosphere. The chlorine-containing plastics may be, for example, waste plastics containing vinyl chloride resin and / or vinylidene chloride resin. In general, waste plastics may contain, in addition to vinyl chloride resin and / or vinylidene chloride resin, resins such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polycarbonate, and acryl butadiene styrene, which are used in packaging films, home appliances, food trays, clothing, etc. The waste plastics may also be RPF (Refuse-Derived Paper and Plastics Densified Fuel). The amount of chlorine in the chlorine-containing plastics when burned may be 0.5 to 20% by mass, preferably 0.6 to 10% by mass, and more preferably 1 to 5% by mass. The oxidizing atmosphere is not particularly limited as long as it contains oxygen, but preferably has an oxygen volume concentration of 0.1 to 24% by volume. The oxidizing atmosphere may be, for example, air. The temperature at which the chlorine-containing plastic is burned is preferably 700 to 1100°C, more preferably 750 to 1050°C, and even more preferably 800 to 1000°C.

[0038] The hydrogen chloride-containing gas preferably contains oxygen. That is, the atmosphere of the hydrogen chloride-containing gas may be an oxidizing atmosphere. In this case, the average volume concentration of oxygen in the hydrogen chloride-containing gas is preferably 0.1 to 24 volume%, more preferably 5 to 24 volume%, even more preferably 10 to 24 volume%, and particularly preferably 15 to 24 volume%. The average volume concentration of oxygen means the average value of the oxygen concentration in the reaction apparatus from the start to the end of the contact time. The hydrogen chloride-containing gas may contain oxygen, nitrogen, carbon dioxide, etc. in addition to hydrogen chloride.

[0039] When using hydrogen chloride generated by burning chlorine-containing plastics, a reaction system for generating hydrogen chloride may be provided separately from the reaction system for heating woody biomass and / or its combustion ash, and the hydrogen chloride may be generated in that reaction system.

[0040] When using hydrogen chloride generated by burning chlorine-containing plastics, the hydrogen chloride may be generated by heating (combusting) the woody biomass and / or its combustion ash in a reaction system for heating the woody biomass and / or its combustion ash (see FIG. 2). That is, the heating step may be a step of heating the woody biomass and / or its combustion ash with the chlorine-containing plastics.

[0041] When the heating step is a step of heating woody biomass and a chlorine-containing plastic, the proportion of the chlorine-containing plastic may be 1 to 30 parts by mass, preferably 1.5 to 10 parts by mass, and more preferably 2 to 7.5 parts by mass, per 100 parts by mass of woody biomass.

[0042] When the heating step is a step of heating woody biomass combustion ash and a chlorine-containing plastic, the proportion of the chlorine-containing plastic may be 20 to 3000 parts by mass, 30 to 1000 parts by mass, or 100 to 600 parts by mass per 100 parts by mass of the woody biomass combustion ash.

[0043] When hydrogen chloride is generated by heating a chlorine-containing plastic together with woody biomass and / or its combustion ash in a reaction system for heating the woody biomass and / or its combustion ash, the chlorine-containing plastic and the woody biomass and / or its combustion ash may be introduced into the reaction system simultaneously or separately.

[0044] Even when a chlorine-containing plastic is heated together with woody biomass and / or its combustion ash in a reaction system for heating the woody biomass and / or its combustion ash, a gas containing hydrogen chloride may be introduced as the atmospheric gas.

[0045] The heating temperature of the woody biomass and / or its combustion ash is 700 to 1100°C, as this allows stable modification of the woody biomass and / or its combustion ash. The heating temperature is preferably 750 to 1050°C, more preferably 800 to 1000°C.

[0046] The heating time for woody biomass and / or its combustion ash is preferably 1 to 120 minutes, more preferably 10 to 120 minutes, even more preferably 15 to 120 minutes, and particularly preferably 40 to 90 minutes, because this allows the woody biomass and / or its combustion ash to be stably modified.

[0047] The starting point of the heating time may be the point at which woody biomass and / or its combustion ash is introduced into a reaction system heated to 700 to 1100°C in an atmosphere of gas containing hydrogen chloride, or the point at which gas containing hydrogen chloride is introduced into a reaction system in which woody biomass and / or its combustion ash is heated to 700 to 1100°C in an atmosphere other than gas containing hydrogen chloride. When using hydrogen chloride generated by burning chlorine-containing plastics, the point at which the specified gas is introduced can be determined, for example, based on a relationship between heating time and the amount of hydrogen chloride generated, which is determined in advance.

[0048] <Recovery process> This step is a recovery step for recovering fly ash discharged together with the gas in the heating step. The fly ash recovered by the dust collector here may be reformed combustion ash.

[0049] The flow velocity of the hydrogen chloride-containing gas discharged in the heating step may be 2 to 20 m / s, since this allows for efficient recovery of fly ash. The flow velocity of the hydrogen chloride-containing gas discharged in the heating step can be adjusted, for example, by adjusting the amount of air introduced into the combustion furnace. The flow velocity is preferably 5 to 15 m / s, more preferably 7 to 12 m / s.

[0050] The amount of water-soluble potassium (KO) in the reformer combustion ash is greater than the amount of water-soluble potassium (KO) in woody biomass and / or its combustion ash. The amount of water-soluble potassium (KO) in the reformer combustion ash may be, for example, 1.0 to 10.0 mass%, preferably 1.2 to 7.0 mass%, and more preferably 1.5 to 5.0 mass%. Here, the amount of water-soluble potassium (KO) in the reformer combustion ash can be measured by the following method. First, the absolute amount of KO in the reformer combustion ash (g) is measured in accordance with JIS R 5202:2010 "Methods for Chemical Analysis of Cement." Next, water in an amount 10 times the mass of the reformer combustion ash is added to the reformer combustion ash, and the mixture is stirred for 30 minutes to dissolve the water-soluble potassium. The residual solids are recovered by filtration, and the absolute amount of KO in the residual solids (g) is measured in accordance with JIS R 5202:2010 "Methods for Chemical Analysis of Cement." Next, the amount of water-soluble potassium (K2O) in the reformed combustion ash can be calculated from the obtained absolute amount (g) of K2O in the reformed combustion ash and the absolute amount (g) of K2O in the residual solid content based on the following formula (1). Amount of water-soluble potassium (KO) in reformed combustion ash (mass%) = [(absolute amount of K2O in reformed combustion ash (g) - absolute amount of K2O in residual solids (g)) / (total amount of reformed combustion ash (g))] × 100 (1)

[0051] The proportion of water-soluble potassium (K2O) in the total potassium (K2O) amount of the reformed combustion ash is higher than the proportion of water-soluble potassium (K2O) in the total potassium (K2O) amount of woody biomass and / or its combustion ash. The proportion of water-soluble potassium (K2O) in the total potassium (K2O) amount of the reformed combustion ash may be, for example, 30 mass% or more. Here, the proportion of water-soluble potassium (K2O) in the total potassium (K2O) amount of the reformed combustion ash can be calculated based on the following formula (2) from the absolute amount of K2O (g) of the reformed combustion ash and the absolute amount of K2O (g) of the residual solid content. The proportion of water-soluble potassium (KO) in the total amount of potassium (KO) in reformed combustion ash (mass%) = [(absolute amount of K2O in reformed combustion ash (g) - absolute amount of K2O in residual solids (g)) / (absolute amount of K2O in reformed combustion ash (g))] × 100 (2)

[0052] [Method for modifying woody biomass and / or its combustion ash] In one embodiment, a method for reforming woody biomass and / or its combustion ash includes a heating step of heating woody biomass and / or its combustion ash at 700 to 1100°C in an atmosphere of a gas containing hydrogen chloride, and a recovery step of recovering fly ash discharged together with the gas containing hydrogen chloride in the heating step. The molar ratio of the amount of potassium in the woody biomass and / or its combustion ash to the amount of chlorine in the gas containing hydrogen chloride is 0.01 to 1.40. This reforming method can reform woody biomass and / or its combustion ash into reformed combustion ash with an increased proportion of water-soluble potassium. Note that the materials, equipment, etc. used in the method for reforming woody biomass and / or its combustion ash are similar to the materials, equipment, etc. used in the method for producing reformed combustion ash. Therefore, redundant explanations will be omitted here.

[0053] [Method of producing low-potassium combustion ash] In one embodiment, a method for producing low-potassium combustion ash is provided for obtaining low-potassium combustion ash having a reduced potassium content from the reformed combustion ash produced by the above-described method. The method includes at least a washing step.

[0054] <Cleaning process> This process involves washing the reformer combustion ash with water to remove soluble matter. More specifically, this process involves stirring a fixed amount of reformer combustion ash and water to prepare a slurry, and separating the insoluble reformer combustion ash (low-potassium combustion ash) from the soluble matter. The soluble matter includes alkali metal salts such as potassium chloride that have dissolved from the reformer combustion ash. This process is usually carried out after cooling the reformer combustion ash to a temperature of 100°C or less (e.g., room temperature of 25°C).

[0055] The reforming combustion ash and water can be stirred using a commonly used stirring device. The reforming combustion ash and water may be stirred while being heated, if necessary.

[0056] When the reforming combustion ash and water are stirred, the mass ratio of water to the reforming combustion ash (mass of water / mass of reforming combustion ash) is preferably 1 to 20, since this allows for efficient removal of alkali metal salts. The mass ratio is more preferably 3 to 15, and even more preferably 5 to 12.

[0057] The water used to wash the reforming combustion ash may be hydrochloric acid water containing hydrogen chloride. By using hydrochloric acid water, alkali metal salts such as potassium chloride in the reforming combustion ash can be more thoroughly eluted. The concentration of the hydrochloric acid water is not particularly limited, but may be 0.01 to 2 mol / L. The hydrochloric acid water may be a diluted version of commercially available hydrochloric acid water. Furthermore, the hydrochloric acid water may include hydrochloric acid water obtained by gas-liquid contact of hydrogen chloride in a hydrogen chloride-containing gas discharged in the heating step of the method for producing reforming combustion ash.

[0058] The insoluble reformed combustion ash (low-potassium combustion ash) can be separated from the soluble matter by filtration. The solid residue obtained by filtration may be dried. When drying is performed, the conditions can be, for example, 20 to 300°C and 0.1 to 100 hours.

[0059] [Method for recycling low-potassium combustion ash into cement resources] In one embodiment, the method for recycling low-potassium combustion ash into a cement resource uses the low-potassium combustion ash produced by the above-described method as a cement raw material. Since the potassium content of the low-potassium combustion ash produced by the above-described method is sufficiently reduced, it can be used as a cement raw material and can be recycled into a cement resource. [Example]

[0060] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0061] [Preparation of woody biomass combustion ash] The woody biomass combustion ash was obtained by burning wood chips and palm kernel shells (PKS) in a circulating fluidized bed furnace and collecting the ash using a dust collector. The physical properties and composition of the woody biomass combustion ash are shown in Tables 1 and 2. The chemical composition analysis values ​​(%) and loss on ignition of the woody biomass combustion ash in Tables 1 and 2 were measured in accordance with JIS R 5202:2010, "Methods for Chemical Analysis of Cement," while the density and Blaine specific surface area of ​​the woody biomass combustion ash were measured in accordance with JIS R 5201:2015, "Physical Testing Methods for Cement." The average particle size of the woody biomass combustion ash in Table 1 was the median diameter (D50: particle size at which the cumulative frequency reaches 50%) measured using a laser diffraction particle size analyzer (SALD-2200, Shimadzu Corporation). The chemical composition analysis values ​​(%) in Table 2 were measured using an X-ray fluorescence analyzer (Simultix12, Rigaku Corporation).

[0062] The amount of water-soluble potassium (KO) in the woody biomass combustion ash in Table 1 was measured using the following method. First, the absolute amount of KO (g) in the woody biomass combustion ash was measured in accordance with JIS R 5202:2010, "Methods for Chemical Analysis of Cement." Next, 10 times the mass of water relative to the mass of the woody biomass combustion ash was added to the woody biomass combustion ash, and the mixture was stirred for 30 minutes to dissolve the water-soluble potassium. The residual solids were recovered by filtration, and the absolute amount of KO (g) in the residual solids was measured in accordance with JIS R 5202:2010, "Methods for Chemical Analysis of Cement." Next, the amount of water-soluble potassium (KO) in the woody biomass combustion ash was calculated using the absolute amount of KO (g) in the woody biomass combustion ash and the absolute amount of KO (g) in the residual solids, based on the following formula (3): Amount of water-soluble potassium (KO) in reformed combustion ash (mass%) = [(absolute amount of K2O in woody biomass combustion ash (g) - absolute amount of K2O in solid residue (g)) / (total amount of woody biomass combustion ash (g))] × 100 (3)

[0063] The proportion of water-soluble potassium (KO) in the total amount of potassium (KO) in the woody biomass combustion ash in Table 1 can be calculated from the absolute amount of KO (g) in the woody biomass combustion ash and the absolute amount of KO (g) in the solid residue, based on the following formula (4): The proportion of water-soluble potassium (KO) in the total amount of potassium (KO) in reformed combustion ash (mass%) = [(absolute amount of K2O in woody biomass combustion ash (g) - absolute amount of K2O in solid residue (g)) / (absolute amount of K2O in woody biomass combustion ash (g))] × 100 (4)

[0064] [Table 1]

[0065] [Table 2]

[0066] [Preparation of chlorine-containing plastics] (1) RPF (solid fuel containing waste paper and waste plastic, with the physical properties shown in Table 3) Measured in accordance with JIS M 8820:2000: Total moisture Measured in accordance with JIS M 8812:2006: Volatile matter, fixed carbon Measured in accordance with JIS Z 7302:2009: Higher heating value, lower heating value, K2O, Cl (2) Polyvinyl chloride reagent (polyvinyl chloride powder, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., chlorine content in polyvinyl chloride: 56.0% by mass)

[0067] [Table 3]

[0068] Example 1 [Production and evaluation of reformed combustion ash (1)] <Production of reformed combustion ash> The reformed combustion ash was produced using the reformed combustion ash production equipment shown in Figure 2. RPF and polyvinyl chloride reagent were continuously heated at 800 °C in a rotary kiln furnace as a combustion furnace, along with combustion ash A, which was woody biomass combustion ash. The amount of each raw material fed to the rotary kiln was set so that the molar ratio of the potassium content in the woody biomass combustion ash to the chlorine content in the hydrogen chloride-containing gas was 0.37, since the RPF and polyvinyl chloride reagent contained almost no calcium carbonate or other components that react with chlorine. The chlorine content in the RPF and polyvinyl chloride (chlorine content in chlorine-containing plastic: 2.2% by mass) was considered to be the chlorine content in the hydrogen chloride-containing gas. The specific feed amounts of each raw material are shown in Table 4. To combust the combustibles in the RPF, the amount of air introduced into the rotary kiln was adjusted to ensure that the oxygen concentration in the exhaust gas at the outlet was approximately 10% by volume, and the flow rate of the hydrogen chloride-containing gas was set to 9.7 m / s. More precise temperature control was performed using a kerosene burner. Most of the combustion ash A after heating moved with the exhaust gas (gas containing hydrogen chloride), and the fly ash (reformed combustion ash) was collected by a cyclone as a dust collector installed in the outlet path.

[0069] [Table 4]

[0070] <Evaluation of reformed combustion ash> The amount of water-soluble potassium (KO) in the reformer combustion ash was determined according to the following procedure. First, the absolute amount of KO (g) in the obtained reformer combustion ash was measured in accordance with JIS R 5202:2010 "Methods for Chemical Analysis of Cement." Next, 10 times the mass of water relative to the reformer combustion ash was added to the reformer combustion ash and stirred for 30 minutes to dissolve the water-soluble potassium. The residual solids were recovered by filtration, and the absolute amount of KO (g) in the residual solids was measured in accordance with JIS R 5202:2010 "Methods for Chemical Analysis of Cement." Next, the amount of water-soluble potassium (KO) in the reformer combustion ash was calculated from the absolute amount of KO (g) in the obtained reformer combustion ash and the absolute amount of KO (g) in the residual solids according to the following formula (1). The amount of water-soluble potassium (KO) in the reformer combustion ash was 2.1% by mass. Amount of water-soluble potassium (KO) in reformed combustion ash (mass%) = [(absolute amount of K2O in reformed combustion ash (g) - absolute amount of K2O in residual solids (g)) / (total amount of reformed combustion ash (g))] × 100 (1)

[0071] The proportion of water-soluble potassium (K2O) in the total amount of potassium (K2O) in the reforming combustion ash was determined according to the following procedure. The proportion of water-soluble potassium (K2O) in the total amount of potassium (K2O) in the reforming combustion ash was calculated based on the absolute amount of K2O (g) in the reforming combustion ash and the absolute amount of K2O (g) in the residual solid content, according to the following formula (2). The proportion of water-soluble potassium (K2O) in the total amount of potassium (K2O) in the reforming combustion ash was 39 mass%. The proportion of water-soluble potassium (KO) in the total amount of potassium (KO) in reformed combustion ash (mass%) = [(absolute amount of K2O in reformed combustion ash (g) - absolute amount of K2O in residual solids (g)) / (absolute amount of K2O in reformed combustion ash (g))] × 100 (2)

[0072] As shown above, the reformed combustion ash of Example 1 produced by a predetermined production method had a higher amount of water-soluble potassium (KO) and a higher proportion of water-soluble potassium (KO) in the total amount of potassium (KO) compared to combustion ash A. These results confirmed that the production method for reformed combustion ash of the present invention can produce reformed combustion ash with an increased proportion of water-soluble potassium from woody biomass and / or its combustion ash.

[0073] Example 2 [Production and evaluation of modified combustion ash (2)] <Preparation of reactor> Reformed combustion ash was produced using the following reactor. Figure 3 is a schematic diagram of the reactor used in the reference example. The reactor 100 shown in Figure 2 includes a heating section 20 and an exhaust gas trap section 30. The heating section 20 is mainly composed of a ceramic tube 22 filled with wood biomass ash 26, which is the heating target, and a tubular furnace 24 for heating the ceramic tube 22. The ceramic tube 22 has a connecting pipe 44 connecting to the hydrogen chloride generation section 10 and a gas exhaust pipe 46 for exhausting gas from the tubular furnace 24. Hydrogen chloride is introduced into the ceramic tube 22 from the connecting pipe 44. When hydrogen chloride generated by burning chlorine-containing waste is used, hydrogen chloride is generated from the hydrogen chloride generation section 10 and introduced into the ceramic tube 22 from the connecting pipe 44. The exhaust gas trap section 30 is mainly used to trap hydrogen chloride discharged from the gas exhaust pipe 46.

[0074] <Production of reformed combustion ash> 25 g of combustion ash B (100% by mass of fly ash), which is woody biomass combustion ash, was packed into a ceramic tube (outer diameter φ50 mm, inner diameter φ42 mm), and the ceramic tube packed with combustion ash B was placed in a tubular furnace in the heating section. The interior of the tubular furnace was heated to 1000 °C under an air atmosphere. After the tubular furnace reached 1000 °C, a hydrogen chloride-containing gas (oxygen volume concentration: 21% by volume) prepared using air and hydrogen chloride generated by dropping concentrated hydrochloric acid into concentrated sulfuric acid was introduced into the tubular furnace. The amount of hydrogen chloride gas introduced is shown in Table 5. The start of the heating time for combustion ash B in the hydrogen chloride-containing gas atmosphere was determined as the time when the hydrogen chloride-containing gas was introduced, and the heating time was 30 minutes. The tubular furnace was then cooled to room temperature (25 °C), and the reformed combustion ash was recovered. Since the proportion of fly ash in combustion ash B is 100% by mass, combustion ash B after the heating process can be considered as fly ash recovered in the recovery process. The amount of water-soluble potassium (KO) in the reformed combustion ash and the proportion of water-soluble potassium (KO) in the total amount of potassium (KO) in the reformed combustion ash are also shown in Table 5.

[0075] [Table 5]

[0076] As shown in Table 5, the reformed combustion ash of Examples 2-1 to 2-4, which was produced under conditions where the molar ratio of the potassium content in combustion ash B to the chlorine content in the hydrogen chloride-containing gas was 0.01 to 1.40, had a higher amount of water-soluble potassium (KO) and a higher proportion of water-soluble potassium (KO) in the total potassium (KO) content compared to combustion ash B. Furthermore, as shown in Table 5, it was found that the lower the molar ratio of the potassium content in combustion ash B to the chlorine content in the hydrogen chloride-containing gas, the higher the amount of water-soluble potassium (KO) and the higher the proportion of water-soluble potassium (KO) in the total potassium (KO) content. These results confirmed that the method for producing reformed combustion ash of the present invention can produce reformed combustion ash with an increased proportion of water-soluble potassium from woody biomass and / or its combustion ash. [Explanation of symbols]

[0077] 10...hydrogen chloride generation section, 20...heating section, 22...ceramic tube, 24...tubular furnace, 26...wood biomass ash, 30...exhaust gas trap section, 44...connecting pipe, 46...gas exhaust pipe, 100...reaction device

Claims

1. A method for producing reformed combustion ash from woody biomass and / or its combustion ash, which produces reformed combustion ash having an increased proportion of water-soluble potassium, a heating step of heating woody biomass and / or its combustion ash at 700 to 1100°C in an atmosphere of a gas containing hydrogen chloride; a recovery step of recovering fly ash discharged together with the hydrogen chloride-containing gas in the heating step; Equipped with the molar ratio (K / Cl) of the amount of potassium in the woody biomass and / or its combustion ash to the amount of chlorine in the gas containing hydrogen chloride is 0.01 to 1.40; Method for producing reformed combustion ash.

2. The water-soluble potassium (K ２ O) amount is 1.0 to 10.0 mass%; The method for producing reformed combustion ash according to claim 1.

3. the heating step is a step of heating the woody biomass and the chlorine-containing plastic, The ratio of the chlorine-containing plastic is 1 to 30 parts by mass per 100 parts by mass of the woody biomass. The method for producing reformed combustion ash according to claim 1 or 2.

4. The heating step is a step of heating the combustion ash of the woody biomass and the chlorine-containing plastic, The ratio of the chlorine-containing plastic is 20 to 3000 parts by mass per 100 parts by mass of the combustion ash of the woody biomass. The method for producing reformed combustion ash according to claim 1 or 2.

5. The amount of chlorine in the chlorine-containing plastic is 0.5 to 20% by mass. The method for producing reformed combustion ash according to claim 3 or 4.

6. The flow rate of the hydrogen chloride-containing gas discharged in the heating step is 2 to 20 m / s. The method for producing reformed combustion ash according to any one of claims 1 to 5.

7. The hydrogen chloride is hydrogen chloride generated by burning a chlorine-containing plastic. The method for producing reformed combustion ash according to claim 1 or 2.

8. A method for reforming woody biomass and / or its combustion ash, which reforms woody biomass and / or its combustion ash into reformed combustion ash having an increased proportion of water-soluble potassium, a heating step of heating woody biomass and / or its combustion ash at 700 to 1100°C in an atmosphere of a gas containing hydrogen chloride; a recovery step of recovering fly ash discharged together with the hydrogen chloride-containing gas in the heating step; Equipped with the molar ratio (K / Cl) of the amount of potassium in the woody biomass and / or its combustion ash to the amount of chlorine in the gas containing hydrogen chloride is 0.01 to 1.40; A method for modifying woody biomass and / or its combustion ash.

9. A method for producing low-potassium combustion ash, which produces low-potassium combustion ash having a reduced potassium content from reformed combustion ash produced by the production method according to any one of claims 1 to 7, A washing step of washing the reformed combustion ash with water to remove soluble components is provided. A method for producing low-potassium combustion ash.

10. The low-potassium combustion ash produced by the production method according to claim 9 is used as a cement raw material. A method for converting low-potassium combustion ash into a cement resource.

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