CN108884383B

CN108884383B - Chemical heat-storage granules and method for producing same

Info

Publication number: CN108884383B
Application number: CN201780022073.2A
Authority: CN
Inventors: 刘醇一; 大塚泰弘; 冈田翔太
Original assignee: Chiba University NUC; Tateho Chemical Industries Co Ltd
Current assignee: Chiba University NUC; Tateho Chemical Industries Co Ltd
Priority date: 2016-03-31
Filing date: 2017-03-28
Publication date: 2022-02-25
Anticipated expiration: 2037-03-28
Also published as: KR20180123132A; WO2017170582A1; SA518400077B1; CN108884383A; KR102380429B1

Abstract

The invention provides a high-strength chemical heat-storage granule which causes a dehydration endothermic reaction in a low-temperature region of 100 to 350 ℃. A chemical heat storage granule comprising, as main components, at least 1 compound selected from the group consisting of an oxide of magnesium, a hydroxide of magnesium, a composite oxide of magnesium and a composite hydroxide of magnesium, at least 1 compound selected from the group consisting of a lithium compound, a potassium compound and a sodium compound, and a carbon compound, wherein, when the carbon content in the chemical heat storage granule is 12 to 35% by mass, Li, K and/or Na is contained in a range of 0.1 to 50 mol% relative to Mg in the chemical heat storage granule, and further wherein the composite oxide of magnesium and the composite hydroxide of magnesium contain at least 1 element selected from the group consisting of Ni, Co, Cu and Al in a range of 1 to 40 mol% relative to Mg, the chemical heat storage granule exhibits excellent durability in a dehydration endothermic reaction in a low-temperature region of 100 to 350 ℃.

Description

Chemical heat-storage granules and method for producing same

Technical Field

The present invention relates to a chemically heat-accumulative granule which causes a dehydration endothermic reaction at a low temperature of 100 to 350 ℃ and has excellent cycle resistance.

Background

In recent years, reduction in the use of fossil fuels has been demanded due to carbon dioxide emission control, and it has been necessary to utilize exhaust heat in addition to energy saving in each process. As a method for utilizing the exhaust heat, heat storage with warm water of 100 ℃. However, warm water heat storage has the following problems and the like: (1) heat cannot be stored for a long time due to heat dissipation loss; (2) since the amount of sensible heat is small, a large amount of water is required, and miniaturization of the heat storage device is difficult; (3) the output temperature is not constant according to the amount of use, and gradually decreases. Therefore, in order to utilize such exhaust heat for civilian use, it is necessary to develop a heat storage technology with higher efficiency.

As a heat storage technique with high efficiency, a chemical heat storage method is exemplified. Since the chemical heat storage method involves chemical changes such as adsorption and hydration of substances, the amount of heat stored per unit mass is higher than that of a heat storage method based on latent heat and sensible heat of the material itself (water, molten salt, etc.). As the chemical heat storage method, a steam adsorption/desorption method based on adsorption/desorption of steam in the atmosphere, an absorption of ammonia in a metal salt (an ammonia complex formation reaction), an adsorption/desorption reaction based on an organic substance such as alcohol, and the like have been proposed. The water vapor adsorption/desorption method is most advantageous in view of the burden on the environment and the simplicity of the apparatus. As a chemical heat storage material used in the steam adsorption/desorption method, magnesium oxide is known.

Magnesium oxide does not function as a practical heat storage material in a low temperature region of 100 to 300 ℃. This is because the hydroxide of magnesium does not cause an effective dehydration reaction in the low temperature region. In order to solve these problems, a chemical heat storage material has been proposed which is capable of storing heat at about 100 to 300 ℃ by combining Mg and at least 1 metal component selected from the group consisting of Ni, Co, Cu and Al (patent document 1). Further, a chemical heat storage material has been proposed which can store heat at about 100 to 350 ℃ with a high heat storage amount per unit mass or unit volume by adding a hygroscopic metal salt of lithium chloride to magnesium hydroxide (patent document 2). Further, it is disclosed that, in a chemical heat storage material based on calcium hydroxide, aggregation of a chemical heat storage material layer during a dehydration reaction can be suppressed by forming a skeleton structure based on sepiolite or the like, and that a hydration reaction can be performed when the dehydration reaction is shifted to a hydration reaction, and reversibility of the dehydration reaction and the hydration reaction is maintained (patent document 3).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2007 and 309561

Patent document 2: japanese patent laid-open publication No. 2009-186119

Patent document 3: japanese laid-open patent publication No. 2009-256517

Disclosure of Invention

Problems to be solved by the invention

However, in the techniques described in patent documents 1 and 2, when the powder is used as it is as a chemical heat storage material, the reaction area decreases due to aggregation after pulverization due to repetition of hydration reaction and dehydration reaction during operation, and the reactivity as a heat storage system decreases. In addition, the chemical heat storage material described in patent document 3 is formed of a skeleton structure made of sepiolite or the like, and thereby suppresses aggregation of the chemical heat storage material layer during dehydration reaction, but the strength of the skeleton structure is weak, and suppression of aggregation of the chemical heat storage material layer is insufficient.

Accordingly, an object of the present invention is to provide a chemical heat storage body which causes a dehydration endothermic reaction in a low temperature range of 100 to 350 ℃ and has excellent cycle resistance.

Means for solving the problems

The present inventors have conducted various studies to solve the above problems, and as a result, have found that a chemical heat-storing granule comprising, as main components, at least 1 magnesium compound selected from the group consisting of an oxide of magnesium, a hydroxide of magnesium, a composite oxide of magnesium and a composite hydroxide of magnesium, at least 1 alkali metal compound selected from the group consisting of a lithium compound, a potassium compound and a sodium compound, and a carbon compound, has a dehydration endothermic reaction at a low temperature of 100 to 350 ℃, has sufficient strength, and is excellent in cycle resistance, and the present invention has been completed.

The present invention has excellent sufficient strength and excellent cycle resistance in the following embodiments.

The chemical heat-storage granules are mainly composed of at least 1 compound selected from the group consisting of magnesium oxides, magnesium hydroxides, magnesium composite oxides, and magnesium composite hydroxides, at least 1 compound selected from the group consisting of lithium compounds, potassium compounds, and sodium compounds, and a carbon compound, and the carbon content in the chemical heat-storage granules is 12-35 mass%.

ADVANTAGEOUS EFFECTS OF INVENTION

The reason why the chemical heat-accumulative granules of the present invention cause a dehydration endothermic reaction in a low temperature range of 100 to 350 ℃ and have sufficient strength and excellent cycle resistance is that the carbon content in the chemical heat-accumulative granules is controlled to 12 to 35 mass%, and as a result, the strength of the chemical heat-accumulative granules is higher than that of the prior art, and the results (pass rate) of the cycle test are clear. Therefore, even if the heat-accumulative dehydration/hydration cycle is repeated, aggregation due to the pulverization can be suppressed, and a chemical heat-accumulative material having no deterioration in heat-accumulative performance can be provided. In the present invention, the magnesium composite oxide and the magnesium composite hydroxide contain 1 to 40 mol% of at least 1 element selected from Ni, Co, Cu and Al in a wide range relative to Mg, cause dehydration endothermic reaction in a low temperature region of 100 to 350 ℃, and have sufficient strength and excellent cycle resistance. Further, the chemical heat-accumulative granules contain 0.1 to 50 mol% of Li, K and/or Na relative to Mg in the granules, cause dehydration endothermic reaction in a low temperature range of 100 to 350 ℃, and have sufficient strength and excellent cycle resistance.

Detailed Description

[ chemical Heat-accumulative granules ]

The chemical heat storage granules are mainly composed of at least 1 compound selected from the group consisting of magnesium oxides, magnesium hydroxides, magnesium composite oxides, and magnesium composite hydroxides, at least 1 compound selected from the group consisting of lithium compounds, potassium compounds, and sodium compounds, and a carbon compound, and contain Li, K, and/or Na in relation to Mg in the chemical heat storage granules, and the carbon content in the chemical heat storage granules is 12 to 35 mass%.

Here, as the at least 1 compound selected from the group consisting of an oxide of magnesium, a hydroxide of magnesium, a composite oxide of magnesium, and a composite hydroxide of magnesium, magnesium oxide, magnesium hydroxide, or a mixture thereof, or a composite oxide of magnesium, a composite hydroxide, or a mixture thereof containing 1 to 40 mol% of at least 1 element selected from the group consisting of Ni, Co, Cu, and Al with respect to Mg.

As the lithium compound, the potassium compound, and the sodium compound, any compound may be used as long as it has hygroscopicity, adsorbs moisture in the atmosphere, or generates a corresponding hydrate. The lithium compound, potassium compound, and sodium compound are preferably chlorides, hydroxides, oxides, bromides, nitrates, or sulfates that satisfy the above requirements and are easy to handle. The lithium compound is more preferably a lithium halide or a lithium hydroxide, and still more preferably a lithium chloride, a lithium bromide, or a lithium hydroxide. The potassium compound is more preferably a potassium halide or potassium hydroxide, and still more preferably potassium chloride, potassium bromide, or potassium hydroxide. The sodium compound is more preferably a sodium halide or sodium hydroxide, and still more preferably sodium chloride, sodium bromide, or sodium hydroxide. At least 1 compound selected from the group consisting of a lithium compound, a potassium compound, and a sodium compound is added to at least 1 compound selected from the group consisting of an oxide of magnesium, a hydroxide of magnesium, a composite oxide of magnesium, and a composite hydroxide of magnesium, whereby a dehydration endothermic temperature of less than 350 ℃ is exhibited, and the temperature changes depending on the addition ratio.

As the carbon compound, a calcined carbide obtained by calcining a polymer compound in an inert atmosphere, an inorganic carbon compound, or the like may be used as long as it does not change in the hydration/dehydration temperature region.

In the chemical heat-accumulative granules, when the carbon content in the chemical heat-accumulative granules is 12 to 35% by mass, the predetermined effect is exhibited in the range of 0.1 to 50 mol% of Li, K and/or Na with respect to Mg in the chemical heat-accumulative granules, and the content of Li, K and/or Na is preferably 2 to 45 mol%, more preferably 3 to 30 mol%. When the content of Li, K and/or Na is less than 0.1 mol%, the effect of lowering the dehydration temperature cannot be obtained even if the carbon content in the chemical heat-accumulative granules is 12 to 35 mass%, and when it exceeds 50 mol%, the dehydration/hydration reaction of magnesium hydroxide itself is inhibited, and the amount of heat accumulated per unit mass or unit volume is reduced, thereby deteriorating the heat-accumulative performance. The carbon content is preferably in the range of 13 to 33 mass%, more preferably 14 to 30 mass%. When the carbon content is less than 12% by mass, a skeleton structure having sufficient strength cannot be obtained, and when it exceeds 35% by mass, the amount of heat stored per unit mass or unit volume decreases, and the heat storage performance decreases.

The chemical heat storage granules are obtained by processing a powdery raw material composed of a single or a plurality of components into granules larger than the raw material using a binder containing a carbon component, and then carbonizing the granules in an inert atmosphere. The chemical heat-storage granules of the present invention are obtained by granulating a polymer compound constituting a carbon compound as a binder and then carbonizing the granules. The chemical heat storage granules may have a volume density of 0.2 to 1.0g/cm³Left and right pellet (pellet) shapes. The heat-accumulative material of the chemical heat-accumulative granules of the present invention has improved strength, and even if the cycle of heat-accumulative dehydration and hydration is repeated, aggregation due to micronization is suppressed and the heat-accumulative capacity is not lowered.

The chemical heat storage granules can be produced by granulating a mixture containing a chemical heat storage material using a granulator and then subjecting the mixture to a carbonization treatment. The granulation method is not limited, and dry granulation or wet granulation may be used. In the case of wet granulation, the granules may be dried after granulation, passed through a sieve, and then carbonized to obtain a chemically heat-accumulative granules. The particle size of the chemical heat-accumulative granules may be 1 to 20mm, as long as it can be used as a chemical heat-accumulative material. If the particle size is less than 1mm, the steam introduction pipe and the like may be clogged in the chemical heat pump system, and the pipe may be clogged. When the particle diameter exceeds 20mm, large pores are necessary for passing water vapor, and in this case, the strength of the chemical heat-accumulative granules is lowered, and the chemical heat-accumulative granules are easily broken.

The carbon compound in the chemically heat-accumulative granules preferably forms a porous structure. The porous structure is a solid structure having very many pores, and functions as a flow path through which water vapor passes. The porosity of the porous body may be about 10 to 80%, and a structure in which pores are randomly dispersed in the chemical heat storage granules is preferable from the viewpoint of reaction efficiency.

The chemical heat-storage granulated body can be produced by carbonizing at 400 to 800 ℃ in an inert atmosphere, and can be formed into a porous structure by carbonization. When the calcination temperature is less than 400 ℃, the high molecular compound constituting the carbon compound is not carbonized, and when it exceeds 800 ℃, the activity of magnesium oxide is lowered and the hydration reactivity is lowered. The polymer compound constituting the carbon compound may be a polymer compound such as a resin having a high carbon residue ratio during carbonization treatment and/or easily forming a three-dimensional structure. The polymer compound constituting the carbon compound is preferably a mixture of 1 or 2 or more of thermosetting resins such as phenol resin, melamine resin, urea resin, epoxy resin, furan resin, polyamide resin, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, acrylic resin, vinyl chloride resin, fluororesin, polyacetal resin, polycarbonate resin, polyurethane resin, and cellulose, and more preferably at least 1 polymer compound selected from the group consisting of phenol resin, melamine resin, and cellulose.

In order to form a porous structure more easily, a polymer compound which is easily volatilized at 400 to 800 ℃ in an inert atmosphere may be further added. The easily volatile polymer compound is preferably potato starch, corn starch, sweet potato starch, tapioca starch, sago starch, rice starch, amaranth starch, or the like.

The chemical heat storage granules formed from at least 1 compound selected from a composite oxide and a composite hydroxide of magnesium containing 1 to 40 mol% of at least 1 element selected from the group consisting of Ni, Co, Cu and Al with respect to the Mg are those which utilize the following reversible reaction of the magnesium oxide/aqueous chemical heat storage material described in patent documents 1 and 2.

The Δ H of Co and Ni is 50-60 kJ/mol, which is lower than that of Mg, and Cu and Al also show the same values, thus showing the same action effect. The composite magnesium compound containing at least 1 element selected from the group consisting of Ni, Co, Cu and Al shows a dehydration endothermic temperature of less than 350 ℃, and the temperature varies according to the composite composition ratio. As the element, Ni, Co, or Al is preferable, and Ni or Co is more preferable. The content of the element is preferably 3 to 30 mol%, more preferably 10 to 25 mol%. When the content of the element is less than 1 mol%, the effect of lowering the dehydration temperature is not obtained, and when it exceeds 40 mol%, the stored heat amount per unit mass or unit volume is lowered.

The source of at least 1 element selected from the group consisting of Ni, Co, Cu, and Al may be any source as long as it can be mixed with water and easily handled, and it is possible to use chloride, hydroxide, oxide, carbonate, nitrate, and/or sulfate, preferably chloride, nitrate, and/or sulfate, and more preferably chloride. When chloride is used, it has high solubility in water, is rich in handleability, and is easily dispersed uniformly.

After removing the chemical heat-accumulative granules having a small particle size by using a sieve having a mesh size that leaves 80 to 99 mass% of the chemical heat-accumulative granules, the chemical heat-accumulative granules are put in a 500mL plastic container containing 5 nylon balls having a diameter of 15mm to 250mL, and after rotating a turntable at 148rpm for 2 hours, the amount of the granules passing through the sieve used for removing the chemical heat-accumulative granules having a small particle size is preferably 40 mass% or less. When the amount exceeds 40 mass%, the strength of the chemically heat-accumulative granules is insufficient, and when the heat-accumulative dehydration and hydration cycle is repeated, the heat-accumulative performance is deteriorated due to aggregation by the pulverization.

(method for producing chemical Heat-accumulative granules)

The method for producing a chemically heat-accumulative granule comprises:

step (A): preparing a hydroxide of magnesium or a magnesium composite hydroxide containing 1 to 40 mol% of at least 1 element selected from the group consisting of Ni, Co, Cu and Al with respect to Mg;

a step (B): mixing the magnesium hydroxide or magnesium composite hydroxide prepared in the step (A) with at least 1 compound selected from the group consisting of a lithium compound, a potassium compound and a sodium compound in an amount of 0.1 to 50 mol% relative to Mg, and with a polymer compound constituting a carbon compound in an amount of 15 to 60 parts by mass relative to 100 parts by mass of the magnesium hydroxide or magnesium composite hydroxide;

step (C): granulating the mixture containing the magnesium hydroxide or magnesium composite hydroxide obtained in the step (B);

a step (D): classifying the granulated substance containing the magnesium hydroxide or the magnesium composite hydroxide obtained in the step (C); and the number of the first and second groups,

step (E): calcining the mixture containing the magnesium hydroxide or the magnesium composite hydroxide prepared in the step (D) at 400 to 800 ℃ for 1 to 24 hours in an inert atmosphere.

The step of obtaining a magnesium hydroxide in the step (a) preferably includes the steps of:

preparing a magnesium chloride aqueous solution with a concentration of 1-10 mol/L and a sodium hydroxide solution or a calcium hydroxide dispersion solution with a concentration of 1-18 mol/L, simultaneously adding the magnesium chloride aqueous solution and the sodium hydroxide solution or the calcium hydroxide dispersion solution with a reaction rate of 80-150% to react to obtain a magnesium hydroxide slurry, and filtering, washing and drying the obtained magnesium hydroxide slurry to obtain the magnesium hydroxide.

The step of obtaining the magnesium composite hydroxide in the step (a) preferably includes the steps of:

preparing a magnesium chloride aqueous solution having a concentration of 1 to 10mol/L, an aqueous solution containing at least 1 element selected from the group consisting of Ni, Co, Cu and Al having a concentration of 0.1 to 10mol/L, and a sodium hydroxide solution or a calcium hydroxide dispersion having a concentration of 1 to 18mol/L, mixing the magnesium chloride aqueous solution and the solution containing at least 1 element selected from the group consisting of Ni, Co, Cu and Al, adding a sodium hydroxide solution or a calcium hydroxide dispersion having a reaction rate of 80 to 150% to react, thereby obtaining a composite magnesium hydroxide slurry, and filtering, washing and drying the obtained composite magnesium hydroxide slurry, thereby obtaining a composite hydroxide of magnesium.

The step (B) is a step of mixing the magnesium hydroxide or magnesium composite hydroxide prepared in the step (a), at least 1 compound selected from the group consisting of lithium compounds, potassium compounds and sodium compounds in an amount of 0.1 to 50 mol% based on Mg, and a polymer compound constituting a carbon compound in an amount of 15 to 60 parts by mass based on 100 parts by mass of the magnesium hydroxide or magnesium composite hydroxide, and a universal Mixer, a ribbon Mixer (ribbon Mixer), a Spartan Reuser (スパルタンリューザー), or the like can be used for the mixing.

The step (C) is a step of granulating the mixture containing the magnesium hydroxide or magnesium composite hydroxide obtained in the step (B), and a wet extrusion granulator, such as DOME GRAN (ドームグラン), disk granulator (disk granulator), or pellet mill, may be used for the granulation.

[ examples ]

Specifically, the present invention will be described with respect to the strength and cycle resistance of granules using examples in which Ni and Co are representative metal elements and Li is representative alkali metal, and the present invention has sufficient strength and excellent cycle resistance in a wide range in which the magnesium composite oxide and the magnesium composite hydroxide contain 1 to 40 mol% of at least 1 element selected from Ni, Co, Cu and Al with respect to Mg. Further, the granules have sufficient strength and excellent cycle resistance in a wide range in which 0.1 to 50 mol% of Li, K and/or Na is contained in the Mg in the granules. Therefore, the present invention is not limited to the following examples.

[ evaluation ]

(1) Method for measuring quality of Mg, Li, K, Na, Ni, Co, Cu and Al

The measurement sample was added to 12N hydrochloric acid (reagent grade) and perchloric acid (reagent grade), heated and completely dissolved, and then measured using an ICP emission spectrometer (PS3520 VDD Hitachi High-Tech Science Corporation).

(2) Method for measuring carbon content

The contents of Fe, Ba, Ti, Zn, P, Si, and B were measured in addition to Mg, Li, K, Na, Ni, Co, Cu, and Al measured in (1), and with respect to Li, K, and Na, the contents were calculated by conversion of the compounds used and the other elements by conversion of oxides, and the carbon content (%) was calculated by subtracting the chemical component values from 100% assuming that no other components except those chemical components and C were present in the granules.

(3) Method for evaluating durability of chemically heat-accumulative granules

The chemical heat-storage granules are dried at 120 ℃ for 12 hours, and then 200g of the granules are weighed, and in order to remove the chemical heat-storage granules having a small particle size, a sieve which leaves 80 to 99 mass% of the granules on the sieve is used, and the chemical heat-storage granules having a small particle size are removed. Then, a measurement sample from which the small-sized chemical heat-accumulative granules were removed was put into a 500mL plastic container to 250mL, 5 nylon balls having a diameter of 15mm were put into the container, and the container was rotated at 148rpm for 2 hours by a porcelain pot ball mill rotary table. In order to examine pulverization of the granulated substance, the weight of the passed measurement sample was measured using the sieve used for removing the chemically heat-accumulated granulated substance having a small particle size, and the pass rate was calculated.

(4) Method for measuring particle diameter

The particle size of 20 chemically heat-accumulative granules was measured with a slide rule, and the minimum and maximum values were removed to calculate an average value. The diameter of the cylindrical granulated body was defined as the particle diameter.

(5) Method for evaluating durability after cycle test

30g of the chemically heat-accumulative granules were measured and (i) kept at 350 ℃ for 80 minutes to prepare an oxide, (ii) kept at 140 ℃ for 40 minutes to cool, (iii) kept at 140 ℃ for 80 minutes by passing steam to prepare a hydroxide, and (iv) dried at 140 ℃ for 40 minutes. After the 10 cycles of the steps (i) to (iv) were performed, the weight of the passed measurement sample was measured using a sieve having a mesh opening of 1mm, and the pass rate was calculated.

(production of chemical Heat-accumulative granules)

[ example 1]

Anhydrous magnesium chloride having a purity of 98 mass% was dissolved with pure water, and a mixed solution was prepared by adding pure water to a nickel chloride solution having a purity of 97 mass% so that the concentration of Ni ions was 0.8mol/L, and adding a solution in which the concentration of Ni ions was 20 mol% with respect to Mg ions to a magnesium chloride aqueous solution adjusted so that the concentration of Mg ions was 2.0 mol/L.

To the prepared mixed solution, a solution prepared by adding pure water to a reagent-grade sodium hydroxide solution and adjusting the concentration to 2.0mol/L was added dropwise at 5 mL/min so that the reaction rate of sodium hydroxide with respect to magnesium chloride became 90% by using a roller press pump, and the mixture was stirred at 300rpm and reacted at 30 ℃ for 1 hour. And filtering and washing the reacted dispersion liquid of the composite magnesium hydroxide, and drying at 120 ℃ for 12 hours to obtain the composite magnesium hydroxide.

The following were put into a vessel of a universal mixer (DULTON CO., LTD. model 5 DM-r): 10 mol% lithium chloride relative to Mg; 20 parts by mass of a phenol resin powder, a melamine resin solution prepared by adjusting 7.3 parts by mass of a melamine resin to a 77% solution with pure water, and 240 parts by mass of pure water were stirred for 10 minutes at a revolution speed of 62rpm and a rotation speed of 141rpm with respect to 100 parts by mass of composite magnesium hydroxide, to obtain a mixture containing composite magnesium hydroxide as a main component.

Then, the clay-like mixture was put into a hopper of a DOME GRAN (model DG-L1 manufactured by Ltd.) of a wet extrusion granulator in small amounts at a screw rotation speed of 40rpm, a DOME die hole diameter of 3.0mm, a plate thickness of 1.0mm, and an opening ratio of 22.7%, and granulated. After the granulation, the mixture was dried at 100 ℃ for 24 hours and sieved to obtain a granulated body containing composite magnesium hydroxide having a particle size of about 2 to 5mm as a main component.

Then, the resulting granules were carbonized at 600 ℃ for 1 hour in an atmosphere replacement electric furnace (SPU 1518-17V manufactured by MARUSHO DENKI CO., LTD.) while flowing nitrogen gas at a flow rate of 0.25L/min, to obtain a chemically heat-stored granules having a carbon content of 14.4 mass%.

[ example 2]

A chemical heat-accumulative granulated body having a carbon content of 19.6 mass% was obtained in the same manner as in example 1, except that the aqueous solution of nickel chloride was changed to an aqueous solution of cobalt chloride.

[ example 3]

A chemically heat-accumulative granulated material having a carbon content of 28.3 mass% was obtained by the same method as in example 1, except that Ni was not added.

[ example 4]

A chemically heat-accumulative granulated material having a carbon content of 20.6 mass% was obtained in the same manner as in example 1, except that the content of Co ions was 5 mol% based on Mg ions.

[ example 5]

A chemically heat-accumulative granulated material having a carbon content of 32.2 mass% was obtained in the same manner as in example 4, except that 50 parts by mass of a phenolic resin in powder form was used per 100 parts by mass of the composite magnesium hydroxide.

[ example 6]

A chemically heat-accumulative granulated material having a carbon content of 14.5 mass% was obtained in the same manner as in example 4, except that 10 parts by mass of a phenolic resin in powder form was used per 100 parts by mass of the composite magnesium hydroxide.

[ example 7]

A chemically heat-accumulative granulated material having a carbon content of 20.6 mass% was obtained in the same manner as in example 4, except that cellulose was used instead of the melamine resin.

[ example 8]

A chemically heat-accumulative granulated material having a carbon content of 26.4 mass% was obtained in the same manner as in example 1, except that lithium bromide was used instead of lithium chloride.

Comparative example 1

A chemically heat-accumulative granulated material was obtained in the same manner as in example 3 except that 27.3 parts by mass of sepiolite was used instead of the phenol resin and the melamine resin for 100 parts by mass of the composite magnesium hydroxide.

Comparative example 2

The granules could not be formed by the same method as in example 3 without using a polymer compound constituting a carbon compound.

Comparative example 3

A chemically heat-accumulative granulated material having a carbon content of 10.9 mass% was obtained in the same manner as in example 4, except that the amount of the phenolic resin powder was changed to 5 parts by mass based on 100 parts by mass of the composite magnesium hydroxide.

Comparative example 4

A chemically heat-accumulative granulated material having a carbon content of 38.9 mass% was obtained in the same manner as in example 4, except that the amount of the phenolic resin powder was changed to 70 parts by mass based on 100 parts by mass of the composite magnesium hydroxide.

The results are summarized in Table 1.

[ Table 1]

In the determination, the heat-accumulative portion of the chemical heat-accumulative granules, excluding carbon, was regarded as a heat accumulator, and the case where the content was 65% or more was regarded as o, and the case where the content was less than 65% was regarded as x. When the content is less than 65%, the heat storage capacity is decreased.

2 the heat storage content of comparative example 1 was calculated by subtracting the sepiolite used in the mixing.

As is clear from the results in table 1, the chemical heat-accumulative granules of the present invention have a significantly higher strength and can provide a high-strength chemical heat-accumulative granule, as compared with the case where sepiolite is used instead of a carbon compound (comparative example 1) and the case where a polymer compound constituting a carbon compound is not used (comparative example 2).

Industrial applicability

The heat-accumulative granules of the present invention cause dehydration endothermic reaction at a low temperature of 100 to 350 ℃ and have high strength. Therefore, it is suitable for effectively utilizing the heat of the exhaust gas discharged from the engine, the fuel cell, and the like. For example, the heat of the exhaust gas can be applied to shortening of the warm-up operation of the automobile, improvement of the comfort of the passengers, improvement of the fuel consumption, reduction of the harm of the exhaust gas due to the improvement of the activity of the exhaust gas catalyst, and the like. In particular, in the case of an engine, since the load imposed by the operation is not constant and the exhaust output is not stable, direct use of exhaust heat is inevitably accompanied by inefficiency and inconvenience. By using the chemical heat storage system of the present invention, exhaust heat can be temporarily chemically stored and then output in accordance with a heat demand, thereby achieving more desirable use of exhaust heat.

Claims

1. A chemically heat-accumulative granulated product comprising a magnesium compound, an alkali metal compound and a carbon compound as main components, wherein the carbon content in the chemically heat-accumulative granulated product is 26.4% by mass, the magnesium compound is a composite hydroxide of magnesium, the alkali metal compound is lithium bromide in an amount of 10 mol% based on Mg,

the magnesium composite hydroxide contains Ni in the form of chloride, and contains Ni in an amount of 20 mol% based on Mg in the chemically regenerative granules,

the carbon compound in the chemical heat storage granules forms a porous structure,

the method for producing the chemically regenerative granules comprises:

step (A): preparing a composite hydroxide of magnesium containing 20 mol% of Ni with respect to Mg;

a step (B): mixing the magnesium composite hydroxide prepared in the step (a), lithium bromide in an amount of 10 mol% based on Mg, and 27.3 parts by mass of a polymer compound constituting a carbon compound based on 100 parts by mass of the magnesium composite hydroxide;

step (C): granulating the mixture containing the magnesium composite hydroxide obtained in the step (B);

a step (D): classifying the granulated substance of the composite hydroxide containing magnesium obtained in the step (C); and a process for the preparation of a coating,

step (E): and (D) calcining the mixture of the composite hydroxide containing magnesium prepared in the step (D) at 400 to 800 ℃ for 1 to 24 hours in an inert atmosphere.

2. The chemical heat storage granule according to claim 1, wherein the carbon compound having a porous structure is a calcined substance in an inert atmosphere of at least 1 resin selected from the group consisting of a phenol resin, a melamine resin, and cellulose.

3. The chemical heat-accumulative granule of claim 1 or 2, wherein a sieve having a mesh size that leaves 80 to 99 mass% of the chemical heat-accumulative granule is used for the chemical heat-accumulative granule, and after removing the chemical heat-accumulative granule having a small particle diameter, the chemical heat-accumulative granule is put in a 500mL plastic container containing 5 nylon balls having a diameter of 15mm to 250mL, and rotated at 148rpm for 2 hours by a rotary table, and the amount of the sieve used for removing the chemical heat-accumulative granule having a small particle diameter is 40 mass% or less.

4. A method for producing a chemical heat-accumulative granule according to claim 1, comprising: