Co-production method and co-production facility for high-concentration methane-containing biogas and carbonated concrete

Abstract

The purpose of the present invention is to provide a co-production method and co-production facility which are capable of simultaneously performing: purification of biogas containing methane gas at a high concentration; and production of carbonated concrete. Provided are a method and facility for co-producing high-concentration methane-containing biogas and carbonated concrete, wherein biogas is brought into contact with a concrete composition, and carbon dioxide in the biogas is immobilized on the concrete composition, thereby performing production of cured carbonated concrete and purification of biogas containing methane.

Description

Method and equipment for the co-production of high-concentration methane-containing biogas and carbonated concrete.

[0001] This invention relates to a method and equipment for the co-production of high-concentration methane-containing biogas and carbonated concrete.

[0002] From the perspective of wastewater treatment and the effective utilization of its resources, methane (CH4) is produced by methane fermentation using livestock excrement from farms and pigpens, food waste such as food scraps from homes, restaurants, and hotels, and food residues from food processing plants, as well as agricultural product residues. ４ Technologies are being researched to generate and effectively utilize biogas primarily composed of )

[0003] Biogas produced by methane fermentation consists mostly of methane and carbon dioxide. The ratio varies depending on the type of raw material and fermentation conditions, but as an example, methane accounts for approximately 60% by volume and carbon dioxide for approximately 40% by volume. By increasing the concentration of methane in biogas, the power generation efficiency can be improved, and the amount of electricity generated can increase, so there is a desire to purify biogas. Furthermore, since biogas purification is carried out by removing carbon dioxide, purifying biogas can reduce the amount of carbon dioxide released into the atmosphere. However, there was a problem in that purifying biogas increased costs.

[0004] For example, Patent Document 1 below describes a method for treating methane fermentation gas, which involves contacting the methane fermentation gas with a calcium silicate-containing material to reduce the carbon dioxide concentration of the methane fermentation gas.

[0005] Japanese Patent Publication No. 2022-127785

[0006] The method for treating methane fermentation gas described in Patent Document 1 involves using a calcium silicate-containing material to process CO2 in methane fermentation gas. ２ This fixates CO2, reducing the carbon dioxide concentration in methane fermentation gas, and also reduces CO2 ２This method uses a calcium silicate-containing material with immobilized carbon dioxide as a raw material for the cement clinker. Therefore, the use of carbon dioxide from biogas to harden concrete had not been considered.

[0007] This invention has been made in view of these circumstances, and aims to provide a co-production method and equipment that can simultaneously purify biogas containing high concentrations of methane gas and produce carbonated concrete.

[0008] The inventors conducted intensive research to solve the above problem and found that by bringing biogas into contact with a concrete composition, the CO2 in the biogas ２ The gas is removed to produce biogas containing high concentrations of methane, and CO2 in the biogas is also removed. ２The present invention was developed by discovering that the problem can be solved by using gas to perform carbonation and produce carbonated concrete. That is, the present invention is as follows: [1] A method for co-producing high-concentration methane-containing biogas and carbonated concrete, comprising contacting biogas with a concrete composition and fixing the carbon dioxide in the biogas to the concrete composition to produce hardened carbonated concrete and purifying biogas containing methane. [2] The method for co-producing high-concentration methane-containing biogas and carbonated concrete according to [1], wherein the carbonated concrete is precast concrete. [3] The method for co-producing high-concentration methane-containing biogas and carbonated concrete according to [1] or [2], wherein the contact between the biogas and the concrete composition is carried out in an airtight state. [4] The method for co-producing high-concentration methane-containing biogas and carbonated concrete according to any one of [1] to [3], wherein the contact time between the biogas and the concrete composition is (1 / 10000) times or more and (1 / 10) times or less than the curing time of the concrete composition. [5] A co-production facility for high-concentration methane-containing biogas and carbonated concrete, comprising: a gas purification carbonation curing tank having a concrete composition inside, for contacting the concrete composition with biogas to produce carbonated concrete and purify the biogas; a gas supply means for supplying the biogas to the gas purification carbonation curing tank; a gas discharge means for discharging the biogas purified in the gas purification carbonation curing tank; and a transport means for transporting the carbonated concrete produced in the gas purification carbonation curing tank. [6] The co-production facility for high-concentration methane-containing biogas and carbonated concrete according to [5], comprising a plurality of gas purification carbonation curing tanks, wherein the gas supply means circulates the biogas to the gas purification carbonation curing tanks so that the concrete composition in the gas purification carbonation curing tank progresses from a concrete composition with a high degree of carbonation curing to a concrete composition with a low degree of carbonation curing. [7] The facility for the co-production of high-concentration methane-containing biogas and carbonated concrete as described in [5] or [6], further comprising a biogas generator for inputting biomass raw materials and causing methane fermentation to generate biogas.[8] The co-production facility for high-concentration methane-containing biogas and carbonated concrete according to any one of [5] to [7], wherein the carbonated concrete is precast concrete. [9] The co-production facility for high-concentration methane-containing biogas and carbonated concrete according to any one of [5] to [8], wherein the gas-purified carbonated curing tank has an airtight member to prevent leakage of gas in the gas-purified carbonated curing tank.

[10] The co-production facility for high-concentration methane-containing biogas and carbonated concrete according to any one of [5] to [9], wherein the space time of the biogas in the gas-purified carbonated curing tank is (1 / 10000) times or more and (1 / 10) times or less than the curing time of the concrete composition.

[0009] According to the present invention, it is possible to provide a co-production method and equipment that can simultaneously purify biogas containing high concentrations of methane gas and produce carbonated concrete.

[0010] This is a schematic diagram showing the co-production equipment of the first embodiment of the present invention. This is a schematic diagram showing the carbonation curing tank of the co-production equipment of the second embodiment of the present invention. This is a graph showing the results of the example. This is a graph showing the results of the example. This is a graph showing the results of the example. This is a graph showing the results of the example.

[0011] The method and equipment for the co-production of high-concentration methane-containing biogas and carbonated concrete according to the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0012] [Method for Co-production of High-Concentration Methane-Containing Biogas and Carbonated Concrete] The present invention provides a method for co-production of high-concentration methane-containing biogas and carbonated concrete (hereinafter simply referred to as the "co-production method"), which involves contacting biogas with a concrete composition to fix the carbon dioxide in the biogas into the concrete composition, thereby producing hardened carbonated concrete and purifying methane-containing biogas. First, the materials used in the co-production method of the present invention will be described.

[0013] (Biogas) The biogas used in the co-production method of the present invention can be, for example, biogas generated by methane fermentation of biomass raw materials such as sewage sludge, night soil sludge, septic tank sludge, food residues, treated sludge of factory wastewater generated from food factories, livestock manure, household waste, and / or grass and trees. When the biogas generated using these biomass raw materials is not subjected to concentration and / or purification treatment, methane (CH ４ ) is contained at about 50 to 70% by volume, and carbon dioxide (CO ２ ) is contained at about 30 to 45% by volume.

[0014] (Concrete Composition) The concrete composition used in the co-production method of the present invention is not particularly limited, and a general concrete composition can be used. For example, a cement composition containing cement and admixtures can be used. In this specification, concrete is a general term for cement paste, cement mortar, and concrete.

[0015] <<Cement>> Examples of the cement contained in the concrete composition include various Portland cements such as ordinary, early strength, ultra-early strength, low heat, and medium heat Portland cements, various blended cements obtained by mixing blast furnace slag, fly ash, or silica with these Portland cements, filler cements obtained by mixing limestone powder, finely powdered blast furnace slag, etc. with these Portland cements, and environmentally friendly cements (eco-cements) manufactured using municipal waste incineration ash and sewage sludge incineration ash as raw materials. These cements can be used alone or in combination of two or more.

[0016] Further, it is preferable that the cement contains γ-2CaO·SiO ２ (γ-C ２ S) as a mineral composition. By containing γ-C ２ S, the absorption amount of CO ２ can be increased, and carbonation can be efficiently performed. The concentration of γ-C ２ S is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 30% by mass or less in the cement. Note that γ-C ２S is not limited to being included in cement, but may also be added to the concrete composition as an admixture as described later.

[0017] The cement content in the concrete composition used in the co-production method of the present invention is 200 kg / m³ in the cement composition, from the viewpoint of maintaining the strength of the carbonated concrete above a certain level. ３ More than 1000kg / m ３ Preferably containing the following amount: 220 kg / m³ ３ More than 800kg / m ３ It is more preferable to include the following:

[0018] ≪Water≫ The concrete composition used in the co-production method of the present invention is mixed with water, for example, in a pan-type concrete mixer. The amount of water usually used for mixing is determined from the viewpoint of the workability of the concrete composition and to increase the void ratio of the concrete composition, CO ２ From the viewpoint of facilitating contact with the other material, the amount of the binder (total of cement and admixture) is preferably 20 to 150 parts by mass, more preferably 30 to 100 parts by mass, even more preferably 35 to 80 parts by mass, and still more preferably 40 to 60 parts by mass, per 100 parts by mass of the binder (total of cement and admixture).

[0019] ≪Aggregates≫ The concrete composition used in the co-production method of the present invention is economical and increases the void ratio of the concrete composition CO ２ It is acceptable to include aggregates from the perspective of facilitating contact with the material and improving workability. Examples of aggregates include river sand, mountain sand, crushed stone, slag aggregate, and recycled aggregate. These aggregates can be used individually or in combination of two or more types.

[0020] The maximum particle size of the aggregate is preferably 50 mm or less, and more preferably 4 to 40 mm.

[0021] In the cement composition used in the co-production method of the present invention, the amount of aggregate used is preferably 80 to 1000 parts by mass per 100 parts by mass of total cement. If the amount of aggregate used is 100 parts by mass or more, the void ratio of the cement concrete will be increased and CO ２This facilitates contact with the material and improves workability. When the amount of aggregate used is 1000 parts by mass or less, the strength of the carbonated concrete can be increased to a certain level or higher. From this viewpoint, the amount of aggregate used is more preferably 100 to 850 parts by mass, and even more preferably 200 to 650 parts by mass.

[0022] ≪Admixtures≫ The concrete composition used in the co-production method of the present invention preferably contains admixtures. Admixtures are materials used in relatively large quantities among admixture materials, and their own volume is included in the mixed volume of concrete, etc. Admixtures are materials other than cement, water, and aggregate, and are added as needed before pouring to give concrete special properties. Examples of admixtures include blast furnace slag powder, fly ash, silica fume, rapid hardening agent, expansive agent, etc. When the concrete composition contains admixtures, CO2 derived from the raw materials is reduced. ２ This can reduce emissions and improve the durability of carbonated concrete. Furthermore, by appropriately using rapid-setting agents, demolding can be performed earlier, thereby increasing the production efficiency of carbonated concrete.

[0023] The admixture content in the concrete composition is not particularly limited, but from the viewpoint of maintaining the strength of the carbonated concrete above a certain level, it is preferably 3 to 1,000 parts by mass, and more preferably 5 to 300 parts by mass, per 100 parts by mass of the total of cement and admixture.

[0024] Next, the method for co-producing high-concentration methane-containing biogas and carbonated concrete according to the present invention will be described. The co-production method of the present invention involves contacting biogas with a concrete composition and fixing the carbon dioxide in the biogas into the concrete composition, thereby producing hardened carbonated concrete and purifying methane-containing biogas. As a result, the carbon dioxide in the biogas is fixed into the concrete composition, allowing for the separation of carbon dioxide from the biogas and the purification of methane to a high concentration. Furthermore, carbonated concrete can be produced by fixing carbon dioxide into the concrete composition. Specifically, it can be produced by the following method (steps). The co-production method of the present invention includes at least the following step (D): a step (A) of mixing a concrete composition containing cement, aggregate, and admixture with water to produce fresh concrete; a step (B) of filling a formwork with the fresh concrete; a step (C) of curing the fresh concrete filled in the formwork and then removing the formwork to produce precast concrete; and a step (D) of carbonation curing by contacting the precast concrete and biogas.

[0025] (Process (A)) In process (A), a concrete composition containing cement, aggregate, and admixtures is mixed with water to produce fresh concrete. The mix of the fresh concrete is preferably determined considering the molding and water curing methods so that the fresh concrete satisfies the required quality after hardening.

[0026] (Process (B)) In process (B), fresh concrete is filled into formwork or molded into any shape using 3D printing or spraying. When formwork is used, it is preferable that it has a robust structure, can obtain the required shape and dimensions of the concrete, and is easy to assemble and remove. Wooden formwork may be used if the number of forms is small, but steel formwork is preferred. In process (B), after filling the formwork with fresh concrete, mechanical compaction may be performed. Examples of mechanical compaction include vibration compaction, vibration and pressure compaction, vacuum compaction, and compaction using a combination of these.

[0027] (Process (C)) In Process (C), if the formwork is filled, the fresh concrete filled in the formwork is water-cured, and then the formwork is removed to produce precast concrete. The method and duration of water-curing of the fresh concrete filled in the formwork are preferably determined to obtain the required quality. It is preferable to water-cur the fresh concrete filled in the formwork thoroughly, taking care not to expose it to harmful effects such as low temperature, drying, rapid temperature changes, loads, and impacts. The method of water-curing is not particularly limited, but steam curing is preferable from the viewpoint of improving initial strength development and increasing productivity. Steam curing generally involves sending steam generated by a boiler through pipes to a steam curing room, and heating and humidifying the fresh concrete in the formwork under normal pressure to accelerate strength development. The steam curing conditions are not particularly limited, but it is preferable to ensure a predetermined pre-setting time, set the heating rate to 1 to 20°C / hr, apply steam, set the maximum temperature to be in the range of 20 to 60°C, and hold the maximum temperature for 1 to 24 hours. When each condition is within the above range, the initial strength development by steam curing is improved, increasing productivity and resulting in a hardened body with the desired characteristics. After maintaining the maximum temperature reached, it is preferable to gradually lower the temperature in the curing room to prevent cracking in the hydrated hardened body. It is preferable to set the cooling time so that the precast concrete can be removed after the temperature difference with the outside air has become small. Furthermore, wet curing may be performed after steam curing to further improve the quality of the carbonated concrete. Demolding is preferably performed after the strength of the precast concrete has reached a strength that does not hinder handling. The hydrated hardened precast concrete removed from the formwork must be handled in a way that does not impair its shape and dimensions.

[0028] (Process (D)) Process (D) involves carbonation curing of precast concrete by bringing it into contact with biogas to produce carbonated concrete. Carbonation curing involves sending biogas into a carbonation curing room and heating and humidifying the precast concrete in a biogas atmosphere to carbonize the precast concrete. The carbonation of precast concrete proceeds as the biogas diffuses into the voids within the precast concrete and carbonates the cement hydrate. Carbonation curing is preferably carried out in biogas (carbon dioxide concentration of approximately 40 vol%) at a temperature of 20 to 80°C and a humidity of 30 to 100% RH, over a period of 1 hour to 2 weeks, depending on the size of the precast concrete. Process (D) is used to process CO2 in the biogas. ２ It is fixed to the precast concrete, and CO in biogas ２ This reduces the amount of methane. Therefore, the methane concentration in biogas can be made relatively higher, allowing for the purification of high-concentration methane-containing gas.

[0029] It is preferable to carry out the contact between biogas and precast concrete in an airtight state within a carbonation curing chamber. It is preferable to carry out the carbonation curing in the carbonation curing chamber under normal pressure or under a pressurized state of 10 MPa or less. By carrying out the process in an airtight state, biogas can be brought into contact with precast concrete without leakage from the curing tank, thus facilitating the production of carbonated concrete. Furthermore, since biogas leakage is prevented, the yield of high-concentration methane-containing biogas can also be increased. An airtight state means that the amount of biogas leaking from the carbonation curing tank into contact with the concrete composition is within 5% of the biogas supply, and this can be determined from the gas volume at the inlet and outlet of the carbonation curing tank and the concentration of methane gas. Also, since the methane combustion range is 5.0% to 15%, if the amount of biogas leaking from the carbonation curing tank is within 5%, the methane concentration in the atmosphere can be kept below the above-mentioned methane combustion range, allowing for safe operation.

[0030] Furthermore, the contact time between biogas and precast concrete is preferably (1 / 10000) times or more and (1 / 10) times or less than the curing time of the precast concrete. When the concrete composition is CaO only and carbonation curing is performed, the difference in volume between solid and gas per unit amount of substance is the largest, and when comparing the volume per mole, CaO is (56 g / mol) / (3.34 g / cm³). ３ ) = 17 cm ３ It is / mol. 40 volume% CO ２ The ratio is 22.4 L / mol / 0.4 = 56 L / mol. Therefore, CaO and 40 volume% CO ２ The volume difference is approximately 3300 times. That is, when CaO is considered as 1, carbonation curing can be completed by contacting it with 3300 times the volume of biogas. Therefore, by setting the biogas contact time to (1 / 3300) relative to the curing time, carbonation can be carried out efficiently. On the other hand, 10% by volume of the concrete composition is cement, and 10% by volume of that is γ-C ２ If S is used, then 1 volume percent of the concrete composition is γ-C ２ S becomes γ-C ２ Of the 172 molecular weights of S, 112 become CaO. Assuming the density of the concrete composition is 2.4, the above ratio is 3300 × 0.01 × 112 / 172 × 2.4 / 3.34 = 15. That is, 10 volume percent of the concrete composition is cement, and 10 volume percent of that is γ-C ２ If we consider S, the carbonation curing can be completed by contacting it with approximately 15 times the volume of biogas. Therefore, by setting the biogas contact time to (1 / 15) of the curing time, carbonation can be carried out efficiently. Carbonation curing is CO2 ２ Because the curing time differs depending on the concentration of CO2 in the biogas and the composition of the concrete, it is preferable that the contact time between the biogas and the precast concrete be between (1 / 10000) times and (1 / 10) times the curing time of the precast concrete. By setting the contact time within the above range, the CO2 in the biogas is reduced. ２ CO2 in biogas can be efficiently brought into contact with precast concrete. ２This allows for effective separation of biogas and precast concrete. The contact time between biogas and precast concrete is (volume of the carbonation curing tank [m³]). ３ ] / Volumetric flow rate of biogas under standard conditions [m ３ It can be defined by the spatial time obtained using [ / min]. The contact time between biogas and precast concrete can be adjusted by controlling the volumetric flow rate of biogas supplied to the carbonation curing tank where carbonation curing is performed, as well as by adjusting the valve on the discharge side.

[0031] The above description explains a method in which precast concrete is manufactured by steam curing, etc., and then subjected to carbonation curing, but it is not limited to this. For example, step (C) may be omitted, and after filling the formwork with fresh concrete in step (B), carbonation curing in step (D) may be performed on the fresh concrete. Similarly, if the concrete is molded by 3D printing, carbonation curing in step (D) can be performed immediately.

[0032] According to the present invention's method for the co-production of high-concentration methane-containing biogas and carbonated concrete, by fixing carbon dioxide in the biogas into the concrete composition, the purification of biogas containing high concentrations of methane gas and the production of carbonated concrete can be carried out simultaneously. Normally, the purification of biogas is costly, and the production of carbonated concrete also incurs costs for obtaining carbon dioxide. With the co-production method of the present invention, by using carbon dioxide in the biogas, the costs of biogas purification and obtaining carbon dioxide can be reduced. Furthermore, by increasing the methane concentration, power generation efficiency is improved, the amount of electricity obtained increases, and carbon dioxide emissions can also be reduced.

[0033] [Co-production facility for high-concentration methane-containing biogas and carbonated concrete] Next, the co-production facility for high-concentration methane-containing biogas and carbonated concrete of the present invention (hereinafter simply referred to as the "co-production facility") will be described. The co-production facility of the present invention comprises a gas purification carbonated curing tank having a concrete composition inside, for contacting the concrete composition with biogas to produce carbonated concrete and purify the biogas, a gas supply means for supplying the biogas to the gas purification carbonated curing tank, a gas discharge means for discharging the biogas purified in the gas purification carbonated curing tank, and a conveying means for conveying the carbonated concrete produced in the gas purification carbonated curing tank.

[0034] (First Embodiment) Figure 1 is a schematic diagram showing a co-production facility according to the first embodiment of the present invention. The co-production facility 10 of the first embodiment includes a gas purification carbonation curing tank 12 for manufacturing carbonated concrete and purifying biogas. Precast concrete 14 is provided as the concrete composition inside the gas purification carbonation curing tank 12, and carbonation curing is carried out by biogas supplied into the gas purification carbonation curing tank 12. In addition, the biogas supplied into the gas purification carbonation curing tank 12 contains CO ２ However, because it is used for the carbonation curing of concrete, CO in biogas ２ As the concentration decreases and the relative concentration of methane increases, it becomes possible to obtain biogas containing a high concentration of methane.

[0035] The gas purification and carbonation curing tank 12 is equipped with a gas supply means 16 for supplying biogas to the gas purification and carbonation curing tank 12. The gas supply means 16 may include a supply pipe, a valve (not shown), a pump (not shown), etc. The gas purification and carbonation curing tank 12 is also equipped with a gas outlet 18 for discharging the purified biogas (high-concentration methane-containing biogas). The gas outlet 18 may include a discharge pipe, a valve (not shown), a pump (not shown), etc.

[0036] Contact between biogas and precast concrete 14 within the gas purification and carbonation curing tank 12 can be achieved by circulating biogas within the gas purification and carbonation curing tank 12.

[0037] The gas purification and carbonation curing tank 12 is preferably operated in an airtight state in order to efficiently carry out carbonation curing within the tank and to increase the yield of high-concentration methane-containing biogas. An airtight state of the gas purification and carbonation curing tank 12 means that the amount of biogas leaking from the tank is within 5% of the supply amount, and this airtight state can be achieved by having an airtight member that prevents gas leakage from within the tank. Examples of airtight members include sealing members made of elastic material provided at the connection part of the gas purification and carbonation curing tank 12, such as gaskets (packings), O-rings, adhesives, and fillers that prevent biogas leakage from the tank.

[0038] Furthermore, it is preferable that the space time of the biogas in the gas purification carbonation curing tank 12 is between (1 / 10000) and (1 / 10) times the curing time of the precast concrete 14. By setting the space time of the biogas within the above range, the CO in the biogas is reduced. ２ CO can be efficiently brought into contact with the precast concrete 14, and the CO in biogas ２ This allows for effective separation of biogas. The space time of biogas is (volume of the carbonation curing tank [m³] ３ ] / Volumetric flow rate of biogas under standard conditions [m ３ It can be calculated using [ / min].

[0039] Furthermore, the co-production equipment 10 of this embodiment preferably includes a biogas generator 20. The biogas generator 20 is a device that generates biogas by taking biomass raw materials and causing methane fermentation. The biogas generator 20 is configured to take biomass raw materials such as sewage sludge, human waste sludge, septic tank sludge, food residue, treated sludge from factory wastewater generated from food factories, livestock manure, food waste, and / or plants, and to produce biogas by causing methane fermentation of these biomass raw materials.

[0040] The biogas supplied to the gas purification and carbonation curing tank 12 can be supplied by the gas supply means 16 using biogas generated by the biogas generator 20. Alternatively, as shown in Figure 1, the biogas may be supplied by connecting the biogas generator 20 and the gas supply means 16 and directly supplying the biogas generated by the biogas generator 20 to the gas purification and carbonation curing tank 12. Alternatively, the biogas produced by the biogas generator 20 may be filled into a container such as a cylinder, and the cylinder may be connected to the gas supply means 16 to supply the biogas to the gas purification and carbonation curing tank 12.

[0041] The carbonated concrete produced by carbonation curing in the gas-purified carbonation curing tank 12 is transported outside the gas-purified carbonation curing tank 12 by the transport means 24. The transport means 24 can be a manually operated means such as a forklift or trolley, or an automatically operated means such as a belt conveyor.

[0042] The biogas that has passed through the gas purification and carbonation curing tank 12 passes through the discharge pipe from the gas outlet 18 and is filled into the biogas storage tank 22. The biogas that has passed through the gas purification and carbonation curing tank 12 undergoes CO2 conversion within the gas purification and carbonation curing tank 12. ２ However, since it is used for the carbonation curing of precast concrete, CO in biogas ２ By immobilizing the methane, the concentration can be increased, and high-concentration methane-containing biogas can be obtained. The high-concentration methane-containing biogas purified in the gas purification carbonation curing tank 12 is filled into the biogas storage tank 22 and can be used as a raw material for heat and electrical energy.

[0043] In addition, a conventional steam curing section (not shown) may be provided separately from the gas-purified carbonation curing tank 12. The precast concrete 14 can be precast concrete that has been steam-cured in this curing section. Furthermore, the concrete composition provided in the gas-purified carbonation curing tank 12 is not limited to precast concrete. Fresh concrete of the concrete composition may be prepared, and this fresh concrete may be filled into a formwork and placed in the gas-purified carbonation curing tank 12 for carbonation curing.

[0044] (Second Embodiment) Figure 2 is a schematic diagram showing a gas purification carbonation curing tank of a co-production facility according to the second embodiment of the present invention. The co-production facility of the second embodiment is equipped with a plurality of gas purification carbonation curing tanks, and biogas is supplied to the gas purification carbonation curing tanks by a gas supply means so that the concrete composition in the gas purification carbonation curing tank progresses from concrete composition with a high degree of carbonation curing to concrete composition with a low degree of carbonation curing.

[0045] The co-production equipment 110 of the second embodiment includes a first gas purification carbonation curing tank 112a, a second gas purification carbonation curing tank 112b, a third gas purification carbonation curing tank 112c, and a fourth gas purification carbonation curing tank 112d for manufacturing carbonated concrete and purifying biogas (hereinafter collectively referred to as "gas purification carbonation curing tanks 112a, 112b, 112c, and 112d"). It also includes biogas supply ports 114a, 114b, 114c, and 114d for supplying biogas to each of the gas purification carbonation curing tanks 112a, 112b, 112c, and 112d, and biogas discharge ports 116a, 116b, 116c, and 116d for discharging biogas. Furthermore, a gas flow section 118 for circulating biogas is provided between the first gas purification carbonation curing tank 112a and the second gas purification carbonation curing tank 112b, between the second gas purification carbonation curing tank 112b and the third gas purification carbonation curing tank 112c, between the third gas purification carbonation curing tank 112c and the fourth gas purification carbonation curing tank 112d, and between the fourth gas purification carbonation curing tank 112d and the first gas purification carbonation curing tank 112a. The gas flow section 118 is provided by partially sharing with the biogas supply ports 114a, 114b, 114c, 114d and the biogas outlet ports 116a, 116b, 116c, 116d, and by branching using a valve 126.

[0046] Furthermore, each of the biogas supply ports 114a, 114b, 114c, and 114d is connected to the gas supply means 16 shown in Figure 1, and each of the biogas outlets 116a, 116b, 116c, and 116d is connected to the gas outlet 18. In addition, each of the biogas supply ports 114a, 114b, 114c, and 114d, and each of the biogas outlets 116a, 116b, 116c, and 116d are connected to CO2 via valve 126. ２ The carbonation curing tanks that supply and discharge the gas containing the biogas are provided in a changeable configuration. This makes it possible to change the location of the gas purification carbonation curing tank that supplies the biogas and the location of the gas purification carbonation curing tank that discharges the biogas, thereby changing the biogas distribution route. In Figure 2(a), biogas is supplied from the biogas supply port 114a and discharged from the biogas discharge port 116d.

[0047] Furthermore, each gas purification carbonation curing tank 112a, 112b, 112c, and 112d is equipped with precast concrete (hereinafter also simply referred to as "concrete") 122a, 122b, 122c, and 122d with different degrees of carbonation curing, and within each gas purification carbonation curing tank 112a, 112b, 112c, and 112d, the precast concrete is arranged so that it progresses from the precast concrete 122a with a high degree of carbonation curing to the precast concrete 122d with a low degree of carbonation curing, along the biogas flow path. For example, in Figure 2(a), biogas is supplied from the biogas supply port 114a of the first gas purification carbonation curing tank 112a, and biogas is discharged from the biogas discharge port 116d of the fourth gas purification carbonation curing tank 112d. At this time, the valve 126 is controlled so that biogas flows through the gas flow section 118 from the first gas purification carbonation curing tank 112a to the second gas purification carbonation curing tank 112b, from the second gas purification carbonation curing tank 112b to the third gas purification carbonation curing tank 112c, and from the third gas purification carbonation curing tank 112c to the fourth gas purification carbonation curing tank 112d. As a result, the biogas flow path becomes a flow path from the first gas purification carbonation curing tank 112a to the fourth gas purification carbonation curing tank 112d. In the precast concrete, the first gas-purified carbonation curing tank 112a contains the concrete 122a with the highest degree of carbonation curing, followed by the second gas-purified carbonation curing tank 112b containing concrete 122b with a moderately high degree of carbonation curing, the third gas-purified carbonation curing tank 112c containing concrete 122b with a moderately low degree of carbonation curing, and the fourth gas-purified carbonation curing tank 112d containing concrete 122d with a low degree of carbonation curing.

[0048] By arranging the precast concretes 122a, 122b, 122c, and 122d in this manner, the concrete 122a, which has a high degree of carbonation curing, receives CO ２Because high-concentration biogas can be reacted, carbonation curing can be advanced even for precast concrete whose reaction has slowed down due to the progress of carbonation curing. In addition, the gas supplied from the first gas-purified carbonation curing tank 112a through the gas flow section 118 to the second gas-purified carbonation curing tank 112b is less likely to undergo carbonation in the first gas-purified carbonation curing tank 112a, so CO ２ It is not consumed much, CO ２ Biogas with a relatively high concentration is supplied. Therefore, it is possible to cure the concrete 122b, which has undergone a certain degree of carbonation curing in the second gas-purified carbonation curing tank 112b. Furthermore, the gas supplied from the second gas-purified carbonation curing tank 112b to the third gas-purified carbonation curing tank 112c through the gas flow section 118 is CO2 because carbonation curing is taking place in the second gas-purified carbonation curing tank 112b. ２ Gas is consumed, CO ２ It is a biogas with a relatively low concentration. However, the concrete 122c provided in the third gas purification carbonation curing tank 112c is concrete with a relatively low degree of carbonation curing progress, and is more easily carbonized than the concrete 122a and 122b provided in the first gas purification carbonation curing tank 112a and the second gas purification carbonation curing tank 112b, so CO ２ Carbonation curing can be carried out even with low-concentration biogas. Similarly, in the fourth gas purification carbonation curing tank 112d, the gas supplied from the third gas purification carbonation curing tank 112c through the gas flow section 118 to the fourth gas purification carbonation curing tank 112d is treated in the third gas purification carbonation curing tank 112c as CO ２ Gas is consumed, CO ２ It is a low-concentration biogas. However, the precast concrete 122d provided in the fourth gas-purified carbonation curing tank 112d is concrete with a low degree of carbonation curing progress, and is more easily carbonized than the precast concrete provided in the first gas-purified carbonation curing tank 112a, the second gas-purified carbonation curing tank 112b, and the third gas-purified carbonation curing tank 112c, so CO ２ Carbonation curing can be carried out even with low-concentration biogas.

[0049] In this way, by supplying biogas along the biogas distribution route from concrete 122a, which has a high degree of carbonation curing, to concrete 122d, which has a low degree of carbonation curing, CO2 is released into the concrete 122a, which has a high degree of carbonation curing. ２ By contacting concrete with a high concentration of biogas, carbonation curing can be advanced even for concrete that is difficult to cure through carbonation. In addition, concrete 122d with a low degree of carbonation curing can be treated by passing it through a gas-purified carbonation curing tank, which allows CO2 to be released. ２ Although low-concentration biogas will come into contact with the material, the carbonation curing process will not progress well, resulting in CO2 ２ Even when exposed to biogas with a low concentration, carbonation curing can be promoted. Therefore, CO2 in biogas ２ This allows for the effective use of gas and improves reaction efficiency. Furthermore, it reduces the CO2 emissions from the biogas. ２ Because the concentration can be reduced, the methane concentration can be increased, and high-concentration methane-containing biogas can be produced.

[0050] Once the carbonation curing in the first gas-purified carbonation curing tank 112a is complete, the carbonated concrete 122a is removed from the first gas-purified carbonation curing tank 112a, as shown in Figure 2(b). After removing the carbonated concrete 122a from the first gas-purified carbonation curing tank 112a, precast concrete 122e that has not yet undergone carbonation curing is placed in the first gas-purified carbonation curing tank 112a. By placing the precast concrete in this manner, the precast concrete in the gas-purified carbonation curing tanks is arranged so that the degree of carbonation curing progresses in the order of the second gas-purified carbonation curing tank 112b, the third gas-purified carbonation curing tank 112c, the fourth gas-purified carbonation curing tank 112d, and the first gas-purified carbonation curing tank 112a.

[0051] Then, the biogas supply is changed from the distribution route in Figure 2(a) to the biogas supply side, with the valve 126 of the biogas supply port 114b provided in the second gas purification carbonation curing tank 112b being switched to the biogas supply side, and the valve 126 of the biogas discharge port 116a provided in the first gas purification carbonation curing tank 112a being switched to the discharge side, and CO2 is introduced into the gas flow section 118 between the first gas purification carbonation curing tank 112a and the second gas purification carbonation curing tank 112b. ２ This prevents gas containing the substance from circulating. Then, the valve 126 is controlled so that gas passes through the gas flow section 118 between the fourth gas purification carbonation curing tank 112d and the first gas purification carbonation curing tank 112a. As a result, the biogas flow path becomes the second gas purification carbonation curing tank 112b, the third gas purification carbonation curing tank 112c, the fourth gas purification carbonation curing tank 112d, and the first gas purification carbonation curing tank 112a, so that the carbonation curing progresses from the precast concrete 122b, which has a high degree of progress, to the precast concrete 122e, which has a low degree of progress.

[0052] Subsequently, the carbonated concrete, whose carbonation curing has been completed, is removed, and precast concrete that has not yet undergone carbonation curing is installed. Then, the biogas flow path is changed so that the precast concrete with a high degree of carbonation curing progresses is replaced with concrete with a low degree of carbonation curing, thereby reducing the CO content in the biogas. ２ The gas can be efficiently used for carbonation curing, and high-concentration methane-containing biogas with a high methane concentration can be produced.

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Example 1] Assuming biogas, a methane-carbon dioxide mixed gas was prepared to have a carbon dioxide concentration of 40 vol% and a methane concentration of 60 vol%. The concrete composition was prepared by mixing 100 vol parts cement with 300 vol parts sand and 50 vol parts water. (Materials used) Cement: Research-grade ordinary Portland cement (manufactured by the Cement Association) Sand: ISO cement standard sand (manufactured by the Cement Association) Water: Tap water The prepared concrete composition was poured into a 4 x 4 x 16 cm formwork, and cured in the formwork for 24 hours in an environment of 20 degrees Celsius and 80% humidity. After demolding, a test sample simulating precast concrete was produced. Carbonation curing of the concrete composition was performed using the prepared methane-carbon dioxide mixed gas. Carbonation curing was performed at a temperature of 50 degrees Celsius using a single curing tank. The methane-carbon dioxide mixed gas was supplied at a flow rate of 200 cm³ under standard conditions. ３ / min, volume of gas purification carbonation curing tank 100 cm³ ３ The space time for the methane-carbon dioxide mixed gas was 0.5 min. The carbonation curing time was set to 180 min, and the conditions were set so that the space time for the mixed gas in the carbonation curing tank was 1 / 360 of the curing time of the concrete composition. The biogas discharged from the gas-purified carbonation curing tank was CH4. ４ Concentration, CO ２ The concentration and compressive strength of the manufactured carbonated concrete were measured. Compressive strength was measured in accordance with the method specified in JIS R 5201;2015 "Physical Testing Methods for Cement". Compressive strength was measured 7 or 8 days after the completion of the carbonation curing.

[0054] Table 1 shows the CH4 discharged from the gas purification carbonation curing tank after curing time of 1 minute, 10 minutes, and 180 minutes. ４ Concentration (Curing tank outlet CH ４ (Gas concentration), CO ２ Concentration (Curing tank outlet CO ２ It shows the gas concentration and compressive strength.

[0055] Figure 3 shows the CO2 at the curing tank outlet. ２ Gas, CH４ This graph shows the changes in gas and water vapor concentrations with respect to curing time. As shown in Figure 3, the outlet gas from the 50°C curing tank contains a high concentration of water vapor, but as it returns to room temperature, the water vapor pressure decreases and the moisture is removed, so the composition of the dry gas becomes important.

[0056] Furthermore, Figure 4 is a graph showing the change in the gas composition at the curing tank outlet, excluding water vapor, with respect to curing time. As shown in Figure 4, the gas composition at the curing tank outlet, excluding water vapor, is CO2 at the curing tank outlet. ２ The gas concentration was 4% by volume after 1 minute, 31% by volume after 10 minutes, and 39% by volume after 180 minutes, at the curing tank outlet CH ４ The gas concentration was 96% by volume at 1 minute, 69% by volume at 10 minutes, and 61% by volume at 180 minutes. In the initial stages of curing, the reactivity of the concrete composition is high, and CO2 is effectively absorbed. ２ absorbs CH ４ It can be seen that CO can be concentrated. On the other hand, the reactivity of the concrete composition decreases with curing time, and CO ２ Absorption and CH ４ It can also be seen that the degree of concentration decreases. Furthermore, the compressive strength of the concrete composition before carbonation is 22 N / mm². ２ However, as shown in Table 1, the compressive strength of carbonated concrete after carbonation is 43 N / mm². ２ The strength increased.

[0057] Figure 5 shows the total amount of CO2 recovered from the curing tank outlet, excluding water vapor. ２ and CH ４ This graph shows the cumulative change in concentration, and Figure 6 shows the CO2 fixed in 1 kg of concrete composition. ２ This graph shows the change in the mass [g] of CO in relation to the carbonation curing time. When the carbonation curing time is 180 min, the space time of the mixed gas in the carbonation curing tank becomes 1 / 360 of the curing time of the concrete composition, and the amount of CO fixed in 1 kg of concrete composition is 1 / 360. ２ Its mass is 26.4 g, CH ４The integrated concentration was 61% by volume. When the curing was stopped after 10 min, the space time of the mixed gas in the carbonation curing tank became 1 / 20 of the curing time of the concrete composition. At this time, the mass of CO fixed in 1 kg of the concrete composition was 6.2 g, and the integrated concentration of CH was 69% by volume. It is preferable to set the space time of the mixed gas in the carbonation curing tank to be 1 / 10000 or more and 1 / 10 or less of the curing time of the concrete composition. However, when the curing time is shortened, the integrated concentration of CH increases, but the fixed amount of CO in the concrete composition decreases. When the curing time is lengthened, the fixed amount of CO in the concrete composition increases, but the integrated concentration of CH decreases. That is, when the space time of the mixed gas in the carbonation curing tank is shortened, the fixed amount of CO in the concrete composition increases, but the integrated concentration of CH decreases. When the space time is lengthened, the integrated concentration of CH increases, but the fixed amount of CO in the concrete composition decreases. Therefore, it is preferable to select the optimum curing time and space time in consideration of the fixed amount of CO and the compressive strength of the concrete composition relic, and the integrated concentration of CH. Also, as shown in Fig. 2, when a plurality of curing tanks are connected and a state where the concrete composition with a long curing time is arranged on the upstream side and the concrete composition with a short curing time is arranged on the downstream side is always maintained, CO can be effectively absorbed and CH can be continuously concentrated. Since the curing time of the concrete composition can be lengthened, the fixed amount of CO can also be increased. ２ The mass of was 6.2 g, and the integrated concentration of CH ４ was 69% by volume. It is preferable to set the space time of the mixed gas in the carbonation curing tank to be 1 / 10000 or more and 1 / 10 or less of the curing time of the concrete composition. However, when the curing time is shortened, the integrated concentration of CH ４ increases, but the amount of CO fixed in the concrete composition decreases. When the curing time is lengthened, the amount of CO fixed in the concrete composition increases, but the integrated concentration of CH ２ decreases. That is, when the space time of the mixed gas in the carbonation curing tank is shortened, the amount of CO fixed in the concrete composition increases, but the integrated concentration of CH ２ decreases. When the space time is lengthened, the integrated concentration of CH ４ increases, but the amount of CO fixed in the concrete composition decreases. Therefore, considering the fixed amount of CO in the concrete composition relic and the compressive strength, and the integrated concentration of CH ２ it is preferable to select the optimum curing time and space time. Also, as shown in Fig. 2, when a plurality of curing tanks are connected and a state where the concrete composition with a long curing time is arranged on the upstream side and the concrete composition with a short curing time is arranged on the downstream side is always maintained, CO ４ can be effectively absorbed and CH ４ can be continuously concentrated. Since the curing time of the concrete composition can be lengthened, the amount of CO fixed in the concrete composition can also be increased. ２ Therefore, considering the fixed amount of CO in the concrete composition relic and the compressive strength, and the integrated concentration of CH ２ it is preferable to select the optimum curing time and space time. Also, as shown in Fig. 2, when a plurality of curing tanks are connected and a state where the concrete composition with a long curing time is arranged on the upstream side and the concrete composition with a short curing time is arranged on the downstream side is always maintained, CO ４ can be effectively absorbed and CH ２ can be continuously concentrated. Since the curing time of the concrete composition can be lengthened, the amount of CO fixed in the concrete composition can also be increased. ４ can be continuously concentrated, and the curing time of the concrete composition can also be lengthened, so the amount of CO fixed can also be increased. ２ fixed amount can also be increased.

[0058] [Reference Example 1] To confirm the influence of methane, carbonation curing was carried out in the same manner as in Example 1, except that the gas for carbonation curing was adjusted to a mixed gas having a carbon dioxide concentration of 40% by volume and a nitrogen concentration of 60% by volume. The results are shown in Table 1. The CO at the outlet of the curing tank corresponding to the carbonation curing time ２There was no significant difference in gas concentration and compressive strength, confirming that there was no difference between methane and nitrogen.

[0059] [Reference Example 2] To confirm the effect of high concentrations of carbon dioxide, carbonation curing was performed in the same manner as in Example 1, except that the gas mixture used for carbonation curing was adjusted to a concentration of 20% by volume of carbon dioxide and 80% by volume of nitrogen. The results are shown in Table 1. CO ２ Carbonated concrete cured with a gas concentration of 40% by volume showed higher compressive strength after 180 minutes of carbonation curing. Biogas is CO2. ２ Due to its high gas concentration, it was shown to be suitable as a gas for use in carbonation curing.

[0060]

[0061] The high-concentration methane-containing biogas obtained by this invention can be used in the energy sector to generate electricity or as fuel. Furthermore, carbonated concrete can be suitably used in the civil engineering and construction sectors, among others.

[0062] 10, 110 Co-production facility for high-concentration methane-containing biogas and carbonated concrete 12 Gas purification and carbonation curing tank 14 Precast concrete 16 Gas supply means 18 Gas outlet 20 Biogas generator 22 Biogas storage tank 24 Conveying means 112a First gas purification and carbonation curing tank 112b Second gas purification and carbonation curing tank 112c Third gas purification and carbonation curing tank 112d Fourth gas purification and carbonation curing tank 114a, 114b, 114c, 114d Biogas supply outlet 116a, 116b, 116c, 116d Biogas outlet 118 Gas flow section 122a, 122b, 122c, 122d, 122e Precast concrete (carbonated concrete) 126 Valve

Claims

1. A method for the co-production of high-concentration methane-containing biogas and carbonated concrete, comprising contacting biogas with a concrete composition to fix carbon dioxide in the biogas to the concrete composition, thereby producing hardened carbonated concrete and purifying methane-containing biogas.

2. The method for co-producing high-concentration methane-containing biogas and carbonated concrete according to claim 1, wherein the carbonated concrete is precast concrete.

3. The method for co-producing high-concentration methane-containing biogas and carbonated concrete according to claim 1 or 2, wherein the contact between the biogas and the concrete composition is carried out in an airtight state.

4. The method for co-producing high-concentration methane-containing biogas and carbonated concrete according to claim 1 or 2, wherein the contact time between the biogas and the concrete composition is (1 / 10000) times or more and (1 / 10) times or less than the curing time of the concrete composition.

5. A co-production facility for high-concentration methane-containing biogas and carbonated concrete, comprising: a gas purification and carbonation curing tank having a concrete composition inside, for contacting the concrete composition with biogas to produce carbonated concrete and purify the biogas; a gas supply means for supplying the biogas to the gas purification and carbonation curing tank; a gas discharge means for discharging the biogas purified in the gas purification and carbonation curing tank; and a conveying means for conveying the carbonated concrete produced in the gas purification and carbonation curing tank.

6. The apparatus for co-producing high-concentration methane-containing biogas and carbonated concrete according to claim 5, comprising a plurality of gas-purified carbonation curing tanks, wherein the gas supply means circulates the biogas to the gas-purified carbonation curing tanks so that the degree of carbonation curing of the concrete compositions in the gas-purified carbonation curing tanks progresses from concrete compositions with a high degree of carbonation curing to concrete compositions with a low degree of carbonation curing.

7. The co-production facility for high-concentration methane-containing biogas and carbonated concrete according to claim 5 or 6, further comprising a biogas generator for inputting biomass raw materials and causing methane fermentation to generate biogas.

8. The co-production facility for high-concentration methane-containing biogas and carbonated concrete according to claim 5 or 6, wherein the carbonated concrete is precast concrete.

9. The gas purification and carbonation curing tank has an airtight member for preventing gas leakage from within the gas purification and carbonation curing tank, as described in claim 5 or 6, for the co-production equipment for high-concentration methane-containing biogas and carbonated concrete.

10. The co-production apparatus for high-concentration methane-containing biogas and carbonated concrete according to claim 5 or 6, wherein the space time of the biogas in the gas purification and carbonation curing tank is (1 / 10000) times or more and (1 / 10) times or less than the curing time of the concrete composition.

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