Additives for chemical heat storage materials, chemical heat storage materials, and methods for manufacturing chemical heat storage materials

Abstract

The object of the present invention is to provide an additive for chemical heat storage materials, a chemical heat storage material, and a method for manufacturing a chemical heat storage material that suppresses the loss of reaction characteristics (high heat storage operation temperature and heat storage density) as a chemical heat storage material, while achieving both structural stability and low cost for the chemical heat storage material. [Solution] In solving the above problems, the present invention provides an additive for chemical heat storage materials containing incinerator residue, a chemical heat storage material containing this additive and a compound in which an exothermic reaction by hydration and an endothermic reaction by dehydration can proceed reversibly, and a method for producing a chemical heat storage material comprising a mixing step of mixing incinerator residue and a compound (hydroxide) in which an exothermic reaction by hydration and an endothermic reaction by dehydration can proceed reversibly. According to the present invention, it is possible to easily obtain a chemical heat storage material that suppresses the loss of reaction characteristics as a chemical heat storage material while achieving both structural stability and low cost.

Description

Technical Field

[0001] The present invention relates to an additive for a chemical heat storage material, a chemical heat storage material, and a method for producing a chemical heat storage material.

Background Art

[0002] Chemical heat storage, which performs heat storage and heat release using chemical reactions and enables heat energy storage at normal temperature, is being researched and developed from the perspective of effectively utilizing waste heat (exhaust heat) from heat sources that generate heat during operation, such as driving engines, factories, and facilities for combustion treatment (such as waste incineration facilities).

[0003] A chemical heat storage material is a substance (solid material) used for chemical heat storage, and heat storage and heat release proceed reversibly through a chemical reaction with a reaction gas (mainly water vapor, carbon dioxide, etc.). However, since the chemical reactions that occur in chemical heat storage involve the uptake and release of the reaction gas with respect to the chemical heat storage material (for example, if the reaction gas is water vapor, hydration and dehydration), it is known that wear of the chemical heat storage material occurs by repeatedly performing chemical heat storage. Therefore, various studies have been conducted to improve the durability of chemical heat storage materials.

[0004] For example, Patent Document 1 describes a chemical heat storage material containing a Group 2 element compound (calcium oxide, magnesium oxide, etc.) and a silicone polymer as a chemical heat storage material that is difficult to be pulverized and has a high thermal conductivity.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The Group 2 element compounds (calcium-based compounds and magnesium-based compounds) described in Patent Document 1 have the advantages of high heat storage operating temperatures and heat storage densities, as well as being inexpensive to obtain. On the other hand, using industrial chemical products such as the silicone polymer described in Patent Document 1 to improve the durability of chemical heat storage materials leads to higher costs for the chemical heat storage materials, which presents a challenge in that it makes it difficult to reduce the cost of chemical heat storage materials.

[0007] Furthermore, when substances that undergo repeated hydration and dehydration during chemical heat storage, such as Group 2 element compounds (calcium-based compounds and magnesium-based compounds), are used as chemical heat storage materials, the repeated increase and decrease in volume of the chemical heat storage material leads to wear and tear and pulverization, as described in Patent Document 1. In addition to this, the expansion and coagulation phenomena associated with the hydration reaction of the chemical heat storage material itself affect the reaction rate and continuous operation in the reactor (chemical heat storage device) containing the chemical heat storage material.

[0008] Therefore, the object of the present invention is to provide an additive for chemical heat storage materials, a chemical heat storage material, and a method for manufacturing a chemical heat storage material that suppresses the loss of reaction characteristics (high heat storage operation temperature and heat storage density) as a chemical heat storage material, while enabling both structural stability and cost reduction of the chemical heat storage material. [Means for solving the problem]

[0009] As a result of diligent research into the above-mentioned problems, the inventors of the present invention have discovered that when using a compound in which an exothermic reaction due to hydration and an endothermic reaction due to dehydration can proceed reversibly as a chemical heat storage material, incineration residue, which remains after incineration, can function as an additive to the chemical heat storage material, and have completed the present invention. In other words, the present invention relates to the following additives for chemical heat storage materials, chemical heat storage materials, and methods for producing chemical heat storage materials.

[0010] The additive for chemical heat storage materials of the present invention, which solves the above problems, is characterized by containing combustion residue. As a result of diligent research, the inventors have found that when using a compound in which an exothermic reaction due to hydration and an endothermic reaction due to dehydration proceed reversibly as a chemical heat storage material, it is possible to form a structure (composition) that suppresses the volume change of the compound due to hydration / dehydration by reacting with the components of the combustion residue as the chemical reaction progresses, and that the loss (consumption) of the compound due to a partial change in the structure (composition) of the compound can be compensated for by the components of the combustion residue. The additive for chemical heat storage materials of the present invention is based on this knowledge. Furthermore, since incinerator residue is generally disposed of in landfills as waste, it can be obtained at a lower cost compared to industrial chemical products, and from the perspective of effective utilization of waste, it is possible to reduce the cost and environmental burden associated with the treatment of the incinerator residue itself (waste). As a result, it is possible to provide a chemical heat storage material that suppresses the loss of reaction characteristics as a chemical heat storage material (high heat storage operation temperature and heat storage density) while achieving both structural stability and low cost.

[0011] Furthermore, one embodiment of the additive for chemical heat storage materials of the present invention is characterized in that the combustion residue contains silica. According to this characteristic, when used as an additive for chemical heat storage materials, the silica in the combustion residue reacts with some of the compounds in which exothermic reactions due to hydration and endothermic reactions due to dehydration can proceed reversibly, forming silicate compounds. This makes it possible to further increase the strength of the chemical heat storage material and improve its durability.

[0012] The present invention, which solves the above problems, is characterized by containing the above-mentioned additive for chemical heat storage materials and a compound in which an exothermic reaction by hydration and an endothermic reaction by dehydration can proceed reversibly. The present invention relates to a chemical heat storage material based on the inventors' findings that incinerator residue functions as an additive to the chemical heat storage material. As the chemical reaction related to chemical heat storage progresses, the compounds undergoing reversible exothermic reactions due to hydration and endothermic reactions due to dehydration react with the components of the incinerator residue, forming a structure (composition) that suppresses volume changes of the compounds associated with hydration / dehydration. In addition, the components of the incinerator residue can compensate for the loss (consumption) of the compounds due to partial changes in the structure (composition) of the compounds. Furthermore, since incinerator ash is generally disposed of in landfills as waste, it can be obtained at a lower cost compared to industrial chemical products. From the perspective of effective waste utilization, it is possible to reduce the costs and environmental impact associated with processing the ash itself (waste). This makes it possible to provide a chemical heat storage material (chemical heat storage material composition) that suppresses the loss of the reaction characteristics of the chemical heat storage material (high heat storage operation temperature and heat storage density) while achieving both structural stability and cost reduction.

[0013] Furthermore, one embodiment of the chemical heat storage material of the present invention is characterized by having a particle size of 1 mm or more. This characteristic allows for the full utilization of the properties of the chemical heat storage material, which suppresses expansion and coagulation associated with chemical heat storage. More specifically, in a reactor (chemical heat storage device) containing this chemical heat storage material, the fluidity of the chemical heat storage material in the reactor is improved, enabling improved reaction rates related to chemical heat storage and smooth continuous operation.

[0014] The present invention provides a method for producing a chemical heat storage material to solve the above problems, comprising a mixing step of mixing incinerator residue and hydroxide, wherein the hydroxide is a compound in which an exothermic reaction due to hydration and an endothermic reaction due to dehydration can proceed reversibly. The present invention provides a method for producing a chemical heat storage material that suppresses the loss of reaction characteristics (high heat storage operation temperature and heat storage density) as a chemical heat storage material, while simultaneously achieving both structural stability and low cost. More specifically, as the chemical reaction related to chemical heat storage progresses, a portion of the hydroxide, which is a compound in which the exothermic reaction due to hydration and the endothermic reaction due to dehydration proceed reversibly, reacts with the components of the combustion residue to form a structure (composition) that suppresses the volume change of the compound due to hydration / dehydration, and at the same time, the loss (consumption) of the compound due to a partial change in the structure (composition) of the compound is compensated for by the components of the combustion residue, thereby providing a chemical heat storage material. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an additive for chemical heat storage materials, a chemical heat storage material, and a method for manufacturing a chemical heat storage material that suppresses the loss of reaction characteristics (high heat storage operation temperature and heat storage density) as a chemical heat storage material, while achieving both structural stability and cost reduction of the chemical heat storage material. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram illustrating an apparatus for evaluating embodiments and comparative examples of the present invention. (A) Using an open-top boat-shaped holder, (B) Using a cylindrical tube holder. [Figure 2] This is a photograph showing the state before and after the chemical heat storage reaction when using the apparatus shown in Figure 1A, with an example according to an embodiment of the present invention as the sample. [Figure 3] This is a photograph showing the state before and after the chemical heat storage reaction when Comparative Example 1 according to an embodiment of the present invention is used as a sample and the apparatus shown in Figure 1A is used. [Figure 4] This is a photograph showing the state before and after the chemical heat storage reaction when Comparative Example 2 according to an embodiment of the present invention is used as a sample and the apparatus shown in Figure 1A is used. [Figure 5] This is a photograph showing the state after a chemical heat storage reaction using the apparatus shown in Figure 1B, with an example according to an embodiment of the present invention as the sample. [Figure 6]A photograph showing the state after the reaction related to chemical heat storage when Comparative Example 2 according to an embodiment of the present invention was used as a sample and the apparatus of FIG. 1B was used. [Figure 7] A graph showing the thermogravimetric analysis results when Examples, Comparative Example 1, and Comparative Example 2 according to embodiments of the present invention were used as samples. [Figure 8] A photograph showing the state of the sample during thermogravimetric analysis (heating up) when Examples, Comparative Example 1, and Comparative Example 2 according to embodiments of the present invention were used as samples.

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of an additive for a chemical heat storage material, a chemical heat storage material, and a method for manufacturing a chemical heat storage material according to the present invention will be described in detail. The additive for a chemical heat storage material, the chemical heat storage material, and the method for manufacturing a chemical heat storage material described in the embodiments are merely examples for explaining the additive for a chemical heat storage material, the chemical heat storage material, and the method for manufacturing a chemical heat storage material according to the present invention, and are not limited thereto.

[0018] 〔Additive for Chemical Heat Storage Material〕 First, embodiments of the additive for a chemical heat storage material according to the present invention will be described. The additive for a chemical heat storage material of the present invention contains combustion ash, which is an incineration residue remaining after incinerating a substance, and is used as an additive for a compound that functions as a chemical heat storage material, particularly a compound in which an exothermic reaction due to hydration and an endothermic reaction due to dehydration can proceed reversibly (hereinafter, also referred to as "TCES (Thermochemical Energy Storage) material"). More specifically, the additive for chemical heat storage materials of the present invention is based on the inventors' findings that, as the chemical reaction related to chemical heat storage progresses, a portion of the TCES material reacts with the incinerator residue to form a structure (composition) that suppresses volume changes of the TCES material due to hydration / dehydration, and that the loss (consumption) due to a partial change in the structure (composition) of the TCES material can be compensated for by the components of the incinerator residue. It is used to provide a chemical heat storage material that suppresses the loss of reaction characteristics as a chemical heat storage material (high heat storage operation temperature and heat storage density) while achieving both structural stability and cost reduction of the chemical heat storage material.

[0019] This embodiment will describe the combustion residue contained in the additive for the chemical heat storage material. In this embodiment, the incineration residue refers to the residue left after incineration. The types and proportions of components contained in the incineration residue vary depending on the material being incinerated, but generally, Al, Si, Ca, Mg, and Na are commonly included as constituent elements. In this embodiment, the type of material to be incinerated is not particularly limited, but it is preferable that the incinerated ash contains silica (SiO2). By including silica in the incinerated ash, when applied as an additive for chemical heat storage material to TCES material, this silica reacts with a portion of the TCES material to form a silicate compound. This silicate compound has a structure (composition) that suppresses the volume change of the TCES material due to hydration / dehydration, thereby further increasing the strength as a chemical heat storage material and improving its durability as a chemical heat storage material. Furthermore, it is even more preferable that the incinerated residue contains compounds of constituent elements (metal elements) related to the TCES material. Examples of such compounds include metal oxides, and more specifically, alkaline earth metal oxides such as calcium oxide (CaO) and magnesium oxide (MgO) are preferred examples. This makes it possible to effectively compensate for losses (consumption) due to partial changes in the structure (composition) of the TCES material with the components of the incinerated residue, in a manner that matches the composition of the TCES material.

[0020] In this embodiment, the incineration residue is preferably one that contains a large amount of silica and metal oxides (particularly alkaline earth metal oxides), and is the incineration residue remaining after incinerating materials containing cellulosic components. Specifically, examples include ash (bottom ash) after incinerating papermaking sludge and ash (bottom ash) derived from biomass power generation (wood biomass power generation).

[0021] The combustion residue used as an additive for the chemical heat storage material in this embodiment may be ash (bottom ash) recovered directly from the source (incinerator, etc.), or it may be subjected to treatment to equalize the particle size distribution (separation by sieving, crushing, etc.) or drying (50-60°C). As described later, when applying incinerated residue as an additive for chemical heat storage materials, and when adhering it to the surface of the TCES material, it is preferable that the incinerated residue be in the form of fine particles (fine powder) of 1 mm or less, and more preferably fine particles (fine powder) on the order of 0.1 mm.

[0022] Incineration residue is generally disposed of in landfills as waste, and it has the advantage of being inexpensive to obtain compared to industrial chemical products. Furthermore, from the perspective of effective waste utilization, it is possible to reduce the cost and environmental impact associated with processing the incineration residue itself (waste). In other words, using incineration residue as an additive to TCES materials (additive for chemical heat storage materials) could be one of the new technologies related to waste treatment.

[0023] [Chemical heat storage material (chemical heat storage material composition)] Next, embodiments of the chemical heat storage material according to the present invention will be described. The chemical heat storage material of the present invention contains the above-mentioned additive for chemical heat storage materials and a compound that functions as a chemical heat storage material, in particular a compound (TCES material) in which an exothermic reaction by hydration and an endothermic reaction by dehydration can proceed reversibly. More specifically, the present invention is based on the inventors' findings that combustion residue functions as an additive for chemical heat storage materials. As the chemical reaction related to chemical heat storage progresses, a portion of the TCES material reacts with the combustion residue components contained in the additive for chemical heat storage materials, forming a structure (composition) that suppresses volume changes of the TCES material due to hydration / dehydration. In addition, the loss (consumption) due to a partial change in the structure (composition) of the TCES material can be compensated for by the combustion residue components. As a result, the present invention provides a chemical heat storage material that suppresses the loss of reaction characteristics as a chemical heat storage material (high heat storage operation temperature and heat storage density) while achieving both structural stability and low cost.

[0024] The TCES material contained in the chemical heat storage material in this embodiment will be described below. In this embodiment, the TCES material refers to a compound in which an exothermic reaction due to hydration and an endothermic reaction due to dehydration can proceed reversibly. The hydration / dehydration reactions in this case proceed as gas-solid reactions. An example of a TCES material in this embodiment is a compound in which a reversible oxide / hydroxide reaction proceeds with water (water vapor). Specific examples of such TCES materials include those containing one or more hydroxides selected from the group consisting of calcium hydroxide, magnesium hydroxide, nickel hydroxide, aluminum hydroxide, cobalt hydroxide, copper hydroxide, barium hydroxide, and sodium hydroxide. In the following description, the TCES material used in this embodiment will primarily be a calcium-based TCES material (CaO / Ca(OH)2), which has the advantages of a high heat storage operating temperature and heat storage density, and is readily available at low cost. However, the invention is not limited to this material.

[0025] When the TCES material is CaO / Ca(OH)2, the hydration / dehydration reactions are as shown in Equation 1.

number

[0026] In the reversible reaction shown in Equation 1, the reaction moving to the right is an exothermic reaction due to hydration, and the reaction moving to the left is an endothermic reaction due to dehydration.

[0027] During the chemical reaction shown in Equation 1, the presence of the aforementioned chemical heat storage material additive (burnt residue) allows the reaction between compounds containing constituent elements (Ca) related to the TCES material (CaO, Ca(OH)2) and silica, one of the components of the chemical heat storage material additive (burnt residue), to proceed simultaneously, forming calcium silicate, a type of silicate compound. In other words, it forms a structure (composition) that suppresses the volume change of the TCES material due to hydration / dehydration. Furthermore, although a certain amount of CaO in the TCES material is lost (consumed) at this time, it is replenished because metal oxides (CaO) are contained as components of the burnt residue.

[0028] Furthermore, while the shape and size of the chemical heat storage material in this embodiment are not particularly limited, it is preferable that the particle size be 1 mm or larger. This "particle size" refers to the smallest particle diameter. For example, the material remaining on a sieve with a mesh size of this value can be used. This allows the properties of the chemical heat storage material to be fully utilized, as expansion and aggregation associated with chemical heat storage are suppressed. More specifically, in a reactor (chemical heat storage device) containing this chemical heat storage material, the fluidity of the chemical heat storage material (chemical heat storage material composition) in the reactor is improved, enabling improved reaction rates related to chemical heat storage and smooth continuous operation. While there are no particular limitations on the type (format) of reactor (chemical heat storage device) that houses the chemical heat storage material of this embodiment, applying the chemical heat storage material of this embodiment to a chemical heat storage device that utilizes a moving bed (fluidized bed) will produce particularly remarkable effects.

[0029] Regarding the control of particle size of the chemical heat storage material, this can be achieved by selecting conditions or methods when mixing and granulating the TCES material and the additive for the chemical heat storage material. In this case, a substance that functions as a binder may be added separately. In addition, chemical heat storage material of the desired particle size can be obtained by controlling the particle growth process through granulation (stopping particle growth at a predetermined stage), or by obtaining chemical heat storage material of the desired particle size through crushing treatment. Examples of particle size control for chemical heat storage materials include, for instance, granulating only the TCES material in advance using a conventional method to achieve a predetermined particle size, and then mixing in additives for chemical heat storage materials, or adding a binder to a mixture of TCES material and additives for chemical heat storage materials to achieve a predetermined particle size.

[0030] (Method of manufacturing chemical heat storage materials) The method for producing the chemical heat storage material in this embodiment includes a mixing step of mixing combustion residue, which functions as an additive for the chemical heat storage material, with hydroxide, which is a TCES material.

[0031] The specific methods used in this mixing step are not particularly limited. For example, dry mixing of incinerator residue and hydroxide (such as Ca(OH)2) or wet mixing in the presence of a solvent (binder) such as water or PVA (polyvinyl alcohol) are possible. In this case, the hydroxide used as the TCES material may be introduced into the mixing step in powder form and the mixture with the incinerated residue may be granulated, or granulation may be performed before introducing it into the mixing step. For example, if granulation (granulation) of the TCES material (hydroxide) is performed before the mixing step, mixing the granulated TCES material with the incinerator residue results in the incinerator residue adhering to the surface of the TCES material. In other words, the surface of the granular TCES material becomes covered with fine-grained (fine-powdered) incinerator residue. At this time, as the chemical reaction related to chemical heat storage progresses, components of the incinerator residue and some of the TCES material react on the surface of the TCES material. As a result, a structure (composition) that suppresses the volume change of the TCES material due to hydration / dehydration is efficiently formed on the surface of the TCES material, making it possible to effectively suppress the expansion and aggregation phenomena of the TCES material due to the hydration reaction. [Examples]

[0032] The following describes the additive for chemical heat storage materials, chemical heat storage materials, and methods for producing chemical heat storage materials according to this embodiment, with reference to examples and comparative examples. Note that this embodiment is not limiting to the present invention.

[0033] In the example, papermaking sludge incineration ash was used as the combustion residue in the additive for chemical heat storage materials, Ca(OH)2 was used as the TCES material, and commercially available slaked lime powder (slaked lime special grade, manufactured by Yabashi Kogyo Co., Ltd.) was used. The papermaking sludge incineration ash used in this example mainly consisted of Ca (75% by mass), Si (13% by mass), and Al (7% by mass).

[0034] The chemical heat storage material in this embodiment was prepared as follows. 45g of TCES material and 5g of incinerator residue were weighed and roughly mixed and granulated using a mortar and pestle to obtain a mixture. This mixture was placed in a high-speed stirring granulator (VGmm stirring mixing granulator, manufactured by Powrec Co., Ltd.), and after a mixing step in which 20-50g of water was introduced as a binder (agitator rotation speed 350 rpm, chopper rotation speed 4000 rpm, processing time less than 1 minute), it was dried (50°C, 2 hours) to obtain the resulting material, which was used as the example (chemical heat storage material). The particle size of the example was 1-2 mm.

[0035] On the other hand, the comparative examples used only TCES material (Ca(OH)2) with the same composition as the example, without containing the chemical heat storage material additive (burnt residue) of the present embodiment. Comparative Example 1 was a powdered material, and Comparative Example 2 was a granulated material. In this study, Comparative Example 1 used commercially available slaked lime powder (Special Grade Slaked Lime, manufactured by Yabashi Kogyo Co., Ltd.) as is, while Comparative Example 2 used the slaked lime powder from Comparative Example 1 granulated using a dry granulator (roller compactor, manufactured by Freund Turbo). Comparative Example 1 was a powder with an average particle size of 20-30 μm, while Comparative Example 2 was a granulated material with a particle size of 0.5 mm or larger.

[0036] (Evaluation of structural stability) The samples obtained as Examples, Comparative Example 1, and Comparative Example 2 were evaluated for their structural stability before and after chemical heat storage reactions (hydration / dehydration reactions) using the apparatus shown in Figure 1. Note that Figures 1A and 1B show different sample holder shapes. As shown in Figure 1, the apparatus for sample evaluation consisted of a sample holder 20 containing the sample S, which was placed in a cylindrical reaction section 10. Using this apparatus, a chemical heat storage reaction (hydration / dehydration reaction) was repeated five times. During this process, a thermocouple 30A was provided to measure the temperature inside the reaction section 10, and a thermocouple 30B was provided to measure the temperature inside the sample S. The start and end of the reaction were determined from the temperature difference between thermocouples 30A and 30B. The hydration reaction was carried out by introducing steam and nitrogen into the reaction section 10, and the dehydration reaction was carried out by heating the inside of the reaction section 10. For the hydration reaction, the reaction conditions and steps involved introducing steam and nitrogen into the reaction chamber 10 at a temperature of 400°C, with flow rates of 0.1 ml / min and 100 ml / min, respectively. For the dehydration reaction, the target temperature in the reaction chamber 10 after the hydration reaction was set to 550°C. The temperature inside the reaction chamber 10 was then increased, and the dehydration reaction was deemed complete when the temperature inside the reaction chamber 10 and the temperature inside the sample S both reached 550°C and stabilized using thermocouples 30A and 30B (for example, held for approximately 10 minutes after reaching 550°C). The reaction was then allowed to cool naturally back down to the temperature conditions for the hydration reaction (400°C). These reaction conditions and steps were used to carry out the chemical heat storage reaction (hydration and dehydration), and this process was repeated.

[0037] First, we will show the results when using a boat-shaped holder 21 with an open top, as shown in Figure 1A, as the sample holder 20 of the apparatus for sample evaluation. Figures 2 to 4 are photographs showing the evaluation results for each sample at that time. More specifically, Figure 2 is a photograph showing the state before and after the chemical heat storage reaction when the example sample is used and the apparatus in Figure 1A is used. Figure 3 is a photograph showing the state before and after the chemical heat storage reaction when Comparative Example 1 is used and the apparatus in Figure 1A is used. And Figure 4 is a photograph showing the state before and after the chemical heat storage reaction when Comparative Example 2 is used and the apparatus in Figure 1A is used.

[0038] As shown in Figure 2, when the example sample was used, it can be seen that the appearance (shape) of the sample was maintained before and after the reaction. On the other hand, as shown in Figure 3, when comparative example 1 was used as the sample, it can be seen that the sample aggregated after the reaction, and one large aggregate was formed within the sample holder 20 (boat-shaped holder 21). Furthermore, as shown in Figure 4, when comparative example 2 was used as the sample, although the tendency to aggregate was suppressed more than in comparative example 1, it can be seen that some pulverization had progressed. Furthermore, although the evaluation using the apparatus shown in Figure 1 is performed under atmospheric pressure, considering that chemical heat storage proceeds with the chemical heat storage material (chemical heat storage material composition) contained in the reactor involves pressurized and depressurized states, it is expected that Comparative Examples 1 and 2 will show a more pronounced tendency to aggregate and undergo pulverization.

[0039] Next, the results when a cylindrical tube holder 22 is used as the sample holder 20 of the apparatus for sample evaluation, as shown in Figure 1B, are presented. Figures 5 and 6 are photographs showing the evaluation results for each sample at that time. More specifically, Figure 5 is a photograph showing the state after the chemical heat storage reaction when the example sample is used and the apparatus in Figure 1B is used. The left side of Figure 5 is a photograph showing the state inside the sample holder after the reaction, and the right side of Figure 5 is a photograph of the sample removed from the sample holder. Figure 6 is a photograph showing the state after the chemical heat storage reaction when Comparative Example 2 is used and the apparatus in Figure 1B is used. The left side of Figure 6 is a photograph showing the state inside the sample holder after the reaction, and the right side of Figure 6 is a photograph of the sample removed from the sample holder.

[0040] As shown in Figure 5, when the example was used as a sample, even in the tube holder 22, which has less free space compared to the boat-shaped holder 21, no aggregates were formed before and after the reaction, and pulverization did not progress, indicating that it has sufficient strength as a chemical heat storage material. On the other hand, as shown in Figure 6, when Comparative Example 2 was used as a sample, it can be seen that the sample aggregated and pulverized after the reaction in the tube holder 22, which has less free space.

[0041] In other words, the results shown in Figures 2 to 6 indicate that, in the embodiment according to the present invention, high structural stability as a chemical heat storage material is observed even when the chemical heat storage reaction is repeated. Furthermore, in the embodiment, aggregation and pulverization, as seen in Comparative Examples 1 and 2, are suppressed, demonstrating that even when housed in a reactor (chemical heat storage device), a decrease in the reaction rate related to chemical heat storage is suppressed, enabling stable continuous operation.

[0042] (Evaluation of reaction characteristics of chemical heat storage materials) The samples obtained as Examples, Comparative Example 1, and Comparative Example 2 were evaluated for their reaction characteristics as chemical heat storage materials. Specifically, thermogravimetric analysis (TGA) was performed on Examples, Comparative Example 1, and Comparative Example 2 to evaluate the heat storage operation temperature, which is one of the reaction characteristics of chemical heat storage materials. In this example, the material obtained from the above preparation (in a dry state) was further baked at 120°C for 1 hour and then at 650°C for 2 hours. The conditions for thermogravimetric analysis (TGA) are as follows: Equipment: Differential scanning calorimeter (Thermo plus EVO2, manufactured by Rigaku Corporation) Measurement conditions: Under a helium atmosphere, helium flow rate 100 ml / min Heating conditions: Heat from room temperature to 50°C at a rate of 10°C / min, hold at 50°C for 10 minutes, then heat from 50°C to 900°C at a rate of 10°C / min.

[0043] Figure 7 is a graph showing the results of thermogravimetric analysis for the Example, Comparative Example 1, and Comparative Example 2, and is known as a TG curve. The vertical axis represents the weight of the sample as a percentage of the initial weight (unit: wt%), and represents the change in the weight of the sample. The horizontal axis represents temperature (unit: °C). As shown in Figure 7, the TG curves in all three examples (Example, Comparative Example 1, and Comparative Example 2) showed a similar trend, indicating that the heat storage reaction proceeded at 350-450°C. In other words, the chemical heat storage material (chemical heat storage material composition) containing the additive for chemical heat storage materials (combustion residue) in the Example was shown to have similar reaction characteristics to calcium compounds known as chemical heat storage materials (Comparative Example 1, Comparative Example 2).

[0044] Figure 8 is a photograph showing the state of Example, Comparative Example 1, and Comparative Example 2 during thermogravimetric analysis (during heating: 50°C and 850°C). As shown in Figure 8, in Comparative Example 1, as the temperature rises, a gap forms along the inner wall of the sample holder for thermogravimetric analysis between the sample holder and the sample S filled in the sample holder, indicating a decrease in sample volume. Similarly, in Comparative Example 2, focusing on the sample S near the inner wall of the sample holder for thermogravimetric analysis, as the temperature rises, the distance (gap) from the inner wall of the sample holder increases, indicating a decrease in sample volume, similar to Comparative Example 1. On the other hand, in the Example, there is no change in the appearance of the sample S placed in the sample holder for thermogravimetric analysis regardless of temperature, indicating that no change in sample volume occurs due to the rise in temperature. Therefore, Figure 8 shows that the Example, in conjunction with the evaluation results regarding structural stability described above, possesses high structural stability.

[0045] The embodiments described above are merely examples of additives for chemical heat storage materials, chemical heat storage materials, and methods for manufacturing chemical heat storage materials. The additives for chemical heat storage materials, chemical heat storage materials, and methods for manufacturing chemical heat storage materials according to the present invention are not limited to the embodiments described above, and the additives for chemical heat storage materials, chemical heat storage materials, and methods for manufacturing chemical heat storage materials according to the embodiments described above may be modified without changing the gist of the claims. [Industrial applicability]

[0046] The additive for chemical heat storage materials, the chemical heat storage material, and the method for producing the chemical heat storage material of the present invention are suitably used in the technical field related to chemical heat storage. In particular, they are suitably used as a technology to obtain a chemical heat storage material that suppresses the loss of reaction characteristics of the chemical heat storage material (high heat storage operation temperature and heat storage density) while achieving both structural stability and cost reduction. [Explanation of Symbols]

[0047] 10 Reaction section, 20 Sample holder, 21 Boat-shaped holder, 22 Tube holder, 30A, 30B Thermocouple, S Sample

Claims

1. An additive for chemical heat storage materials, characterized by containing incinerator residue.

2. The additive for chemical heat storage material according to claim 1, characterized in that the combustion residue contains silica.

3. Additive for chemical heat storage material according to claim 1 or 2, A chemical heat storage material characterized by containing a compound in which an exothermic reaction due to hydration and an endothermic reaction due to dehydration can proceed reversibly.

4. The chemical heat storage material according to claim 3, characterized in that the particle size is 1 mm or larger.

5. The process includes a mixing step of mixing incinerated residue and hydroxide, A method for producing a chemical heat storage material, characterized in that the hydroxide is a compound in which an exothermic reaction due to hydration and an endothermic reaction due to dehydration can proceed reversibly.

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