JP2012007061A - Method for producing hydrated salt for heat storage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method for directly producing hydrated salt for heat storage on a site of use.SOLUTION: This method for producing the hydrated salt for heat storage includes a first step, a second step and a third step. In the first step, a raw material 1A having less hydration water than the hydration water of the hydrated salt for heat storage to be produced is filled in a container 2. In the second step, water is fed in the container 2, by such an amount that is not less than the mass difference between the hydrated salt for heat storage to be produced and the raw material 1A and dissolvable of total raw material 1A. In the third step, the aqueous solution 1B in the container 2 is boiled by depressing the inside of the container 2 and concentrated into salt concentration of the hydrated salt for heat storage to be produced.

Description

  The present invention relates to a method for producing a hydrated salt for heat storage.

  A heat storage technique for storing thermal energy is a technique for manipulating heat over a wide temperature range from a very low temperature when heat is used to a very high temperature when heat is generated. In recent years, the application of heat storage technology has been considered even in a relatively low temperature range (200 ° C. or lower) mainly for the purpose of cooling and heating and hot water supply, such as natural energy such as solar heat, which is unused energy, or effective use of nighttime power. R & D continues actively.

  In these relatively low temperature ranges, the latent heat storage method using the latent heat associated with the solidification and melting of the heat storage material exhibits excellent characteristics, and organic materials such as paraffin and fatty acids, or hydrated salts are used as the heat storage material. It has been well examined. In particular, many studies have been made on hydrated salts from the viewpoint of excellent heat storage density and price. Therefore, it is important from the viewpoints of both performance and price to manufacture a desired hydrated salt accurately and inexpensively.

  As a conventional method for producing a hydrated salt, there is a production method using a fluidized bed container, taking calcium chloride hydrate as an example (see, for example, Patent Document 1). In this production method, in a fluidized bed container, anhydrous calcium chloride, calcium chloride monohydrate, calcium chloride dihydrate, or a mixture thereof is allowed to flow as seed particles, and an aqueous solution of calcium chloride is sprayed to form seed particles. Adhere to the surface. By using such a manufacturing process, the hydration number of seed particles is increased. And the calcium chloride hydrate of the desired number of water molecules is produced | generated by adjusting the water vapor partial pressure in a fluidized bed container based on the temperature in a fluidized bed container. An advantage of this production method is that a large amount of calcium chloride hydrate having a desired number of water molecules can be produced with high accuracy.

Japanese Patent No. 4162837

  By the way, in the above manufacturing method, since a special fluidized bed container for forming a fluidized bed is required, calcium chloride hydrate is produced in a factory where the fluidized bed container is installed. However, since the weight of the manufactured calcium chloride hydrate is increased due to hydrated water, it takes a lot of labor to transport it from the factory to the place of use. Therefore, it is desired that a hydrate salt having a desired number of water molecules can be directly produced at the place of use.

  This invention is made | formed in view of the said situation, The objective is to provide the manufacturing method which can manufacture the hydrated salt for thermal storage directly at a use place.

  In order to solve the above-mentioned problem, the present invention is a method for producing a heat storage hydrate salt, the first step of filling a container with a raw material having less hydration water than the heat storage hydrate salt, and the container A second step of supplying water in an amount greater than the mass difference between the hydrated salt for heat storage and the raw material and capable of dissolving the total amount of the raw material, and reducing the pressure in the container to obtain an aqueous solution in the container. And a third step of concentrating the aqueous solution to the salt concentration of the heat storage hydrate salt, and providing a method for producing a heat storage hydrate salt.

  According to the above configuration, the aqueous solution can be boiled at a relatively low temperature by reducing the pressure in the container. Such boiling under reduced pressure is accompanied by sudden large bubble (steam) generation, so that the aqueous solution in the container is vigorously stirred. Thereby, the hydration reaction in an aqueous solution can be promoted, and a hydrated salt having a desired number of water molecules can be produced with high accuracy. And since this manufacturing method can be performed if there exists a container, a pressure reduction means (for example, vacuum pump), and water, the hydrated salt for thermal storage can be directly manufactured at the place of use.

The block diagram of the manufacturing apparatus used for the manufacturing method of the hydrated salt for thermal storage which concerns on 1st Embodiment of this invention. Phase diagram of calcium chloride hydrate Graph showing saturation curve of water and calcium chloride hexahydrate The block diagram of the manufacturing apparatus used for the manufacturing method of the hydrated salt for thermal storage which concerns on 2nd Embodiment of this invention. The block diagram of the manufacturing apparatus of the modification in 2nd Embodiment. The block diagram of the manufacturing apparatus used for the manufacturing method of the hydrated salt for thermal storage which concerns on 3rd Embodiment of this invention. The block diagram of the manufacturing apparatus used for the manufacturing method of the hydrated salt for thermal storage which concerns on 4th Embodiment of this invention. The block diagram of the manufacturing apparatus used for the manufacturing method of the hydrated salt for thermal storage which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram of a production apparatus used in the method for producing a heat storage hydrate salt according to the first embodiment of the present invention. In the present embodiment, a heat storage device 10A including a heat storage container 2 for housing a heat storage material is used as a manufacturing device. That is, the hydrated salt for heat storage is produced in the heat storage container 2 and used as it is as a heat storage material.

  Specifically, the heat storage device 10A includes the above-described heat storage container 2, the heater 3 that heats the heat storage material in the heat storage container 2, the outflow pipe 4 for causing air to flow out of the heat storage container 2, and the heat storage container. 2 is provided with a water supply pipe 5 for supplying water. The outflow pipe 4 is provided with a pressure reducing means (for example, a vacuum pump) 41 for reducing the pressure inside the heat storage container 2 to the atmospheric pressure or lower, and a regulator 42 for adjusting the pressure upstream of the pressure reducing means 41. Is provided. Furthermore, the heat storage container 2 is provided with a pressure sensor 6 for detecting the pressure in the heat storage container 2 and a temperature sensor 7 for detecting the temperature of the aqueous solution 1B described later.

  The heater 3 has a circulation part 31 that penetrates the heat storage container 2 while meandering, for circulating a heat medium that radiates heat to the heat storage material or absorbs heat from the heat storage material. The circulation part 31 is preferably provided with fins 32 for efficient heat exchange between the heat storage material and the heat medium. Examples of the heat medium include water, air, and a refrigerant.

  The manufacturing method which concerns on this embodiment manufactures the hydrated salt for thermal storage using 10 A of thermal storage apparatuses, and contains a 1st process, a 2nd process, and a 3rd process. Hereinafter, each step will be described in detail.

<First step>
First, the heat storage container 2 is filled with the raw material 1A. The raw material 1A may be any material that has less hydration water than the hydrated salt for heat storage to be manufactured, and may be an anhydride (salt itself), or water having a smaller number of water molecules than the hydrated salt for heat storage. It may be a Japanese salt. The total amount of the raw material 1A is preferably solid, but it is also possible to use a raw material coexisting in a solid-liquid state.

As the salt, for example, the following can be used.
KNO ₃
MgCl ₂
Al ₂ (SO ₄ ) ₃
NH ₄ Al (SO ₄ ) ₂
KAl (SO ₄ ) ₂
Sr (OH) ₂
Ba (OH) ₂
MgCl ₂
CH ₃ COONa
Mg (NO ₃ ) ₂
Na ₂ S ₂ O ₃
CaBr ₂
Zn (NO ₃ ) ₂
Na ₂ HPO ₄
Na ₂ SO ₄
LiNO ₃
CaCl ₂
Na ₂ SO ₄ / NaCl / KCl

  For example, when producing calcium chloride hexahydrate as a hydrated salt for heat storage, anhydrous calcium chloride may be used as raw material 1A, or calcium chloride dihydrate may be used. Alternatively, a mixture of anhydrous calcium chloride and calcium chloride dihydrate can be used.

  After the filling of the raw material 1A, the heat storage container 2 has sufficient airtightness so that the raw material 1A in the heat storage container 2 does not absorb moisture in the atmosphere or to perform decompression in the third step described later. And the first step is completed.

  Note that the first step may be performed after the heat storage container 2 is installed at the installation location, or may be performed in advance before the heat storage container 2 is installed at the installation location. That is, the first step may be performed at a place where the heat storage hydrate salt is used, or may be performed at a factory or the like.

<Second step>
After the first step, water having a mass difference between the heat storage hydrate salt to be manufactured and the raw material 1A is supplied from the water supply pipe 5 into the heat storage container 2 at the installation location of the heat storage container 2. That is, more water than the amount necessary for producing the hydrated salt for heat storage is supplied from the raw material 1A, which is derived from the hydration reaction formula of the raw material 1A and water.

  At that time, as shown in FIG. 1, the water from the water supply pipe 5 is preferably supplied upward from the bottom of the heat storage container 2 so as to pass through the raw material 1A from the bottom to the top. When water is sprayed from above the raw material 1A, the supplied water and the raw material 1A are separated due to the density difference between the substances themselves, and their hydration reaction hardly proceeds. On the other hand, if water is supplied so as to pass through the raw material 1A from the bottom to the top, the hydration reaction between water and the raw material 1A can be favorably progressed.

  When the salt is a substance that generates heat by hydration (water absorption) reaction with water, such as calcium chloride, the temperature rises in the second step. For this reason, there is an advantage that boiling easily occurs when the inside of the heat storage container 2 is decompressed in the third step.

  In this embodiment, the amount of water supplied in the second step is such that the total amount of the raw material 1A can be dissolved, in other words, in the liquid phase rather than the boundary between the liquid phase and the solid-liquid coexistence in the phase diagram of the hydrated salt It is also an amount that can achieve the salt concentration on the side. Thereby, ideally, the aqueous solution 1B in a state in which the raw material 1A is completely dissolved is generated. However, since the aqueous solution 1B is stirred by boiling in the third step, a part of the raw material 1A may remain as a solid without dissolving in the aqueous solution 1B generated in the second step.

  As an example, as shown in FIG. 2, when calcium chloride hexahydrate (D point) is produced, water supplied to anhydrous calcium chloride (A point) or calcium chloride dihydrate (B point) is supplied. When all are reacted, an amount of water corresponding to the formation of calcium chloride octahydrate (C point: salt concentration of about 44%) is supplied.

<Third step>
After completion of the second step, the inside of the heat storage container 2 is depressurized to boil the aqueous solution 1B in the heat storage container 2. Thereby, unnecessary water | moisture content is removed from aqueous solution 1B, and aqueous solution 1B is concentrated to the salt concentration of the hydrated salt for thermal storage which should manufacture.

  FIG. 3 shows the relationship between the temperature and pressure in the saturated state of water and calcium chloride hexahydrate. Boiling does not occur unless the temperature of the liquid rises above the saturation temperature corresponding to the pressure of the liquid. Therefore, as can be seen from FIG. 3, for example, in the case of water, boiling does not occur unless it is heated to 100 ° C. or higher at atmospheric pressure (101.32 kPa). However, if the pressure in the container containing water is reduced to, for example, 10 kPa, the water can be boiled even if the temperature of the water is 50 ° C. This tendency is the same for calcium chloride hexahydrate.

  If the inside of the heat storage container 2 is depressurized, the aqueous solution 1B will boil at a relatively low temperature. Since the aqueous solution 1B is stirred by this boiling, the hydration reaction in the aqueous solution 1B can be promoted even if the heater 3 having the fins 32 is disposed in the heat storage container 2.

  The boiling of the aqueous solution 1B can be caused only by reducing the pressure in the heat storage container 2 to the saturated vapor pressure or less corresponding to the temperature of the aqueous solution 1B by the decompression means 41. In this case, the time taken for the salt concentration of the aqueous solution 1B to coincide with the salt concentration of the hydrated salt for heat storage to be produced is measured in advance by experiment and the concentration of the aqueous solution 1B is terminated when this time has elapsed. Also good. Thereby, a hydrated salt having a desired number of water molecules can be easily obtained.

  However, in order to produce the hydrated salt for heat storage in a shorter time, it is preferable to boil the aqueous solution 1B by heating the aqueous solution 1B with the heater 3 in a state where the inside of the heat storage container 2 is decompressed. When the aqueous solution 1B is boiled, bubbles are generated, that is, moisture is vaporized, so that heat is lost as heat of vaporization and the temperature of the aqueous solution 1B is lowered. If the temperature drop is too great, boiling under reduced pressure no longer occurs. Therefore, the aqueous medium 1B is heated by continuing to distribute the heat medium having a constant temperature heated by the heat source to the circulation part 31 of the heater 3. This continuously causes boiling under reduced pressure. Moreover, when the vaporization of water occurs too much, the pressure in the heat storage container 2 increases, and boiling under reduced pressure does not occur. Therefore, it is preferable to heat the aqueous solution 1B by the heater 3 while keeping the pressure in the heat storage container 2 constant by the regulator 42.

  When heating the aqueous solution 1B while keeping the pressure in the heat storage container 2 constant, the concentration of the aqueous solution 1B can be terminated based on the values detected by the pressure sensor 6 and the temperature sensor 7. In this way, a hydrated salt having a desired number of water molecules can be produced with higher accuracy. Specifically, when the temperature of the aqueous solution 1B detected by the temperature sensor 7 reaches the saturation temperature of the hydrated salt for heat storage to be manufactured, corresponding to the pressure in the heat storage container 2 detected by the pressure sensor 6. Then, the concentration of the aqueous solution 1B is completed. Below, operation when manufacturing calcium chloride hexahydrate as an example of the 3rd process is explained.

<Example of the third step>
Water at 80 ° C. is circulated through the circulation part 31 of the heater 3. From FIG. 3, when the saturated vapor pressure when the temperature of calcium chloride hexahydrate reaches 80 ° C., for example, is derived, the value is 12.76 kPa.

  The pressure in the heat storage container 2 is reduced to 12.76 kPa by the decompression means 41, and the pressure is maintained by the regulator 42. In the heat storage container 2, an aqueous solution 1B having a salt concentration corresponding to, for example, calcium chloride octahydrate is generated in the second step. As shown in FIG. 3, since the saturation curve of this aqueous solution is above calcium chloride hexahydrate, the aqueous solution 1B in the heat storage container 2 boils at a temperature lower than 80 ° C. Since water vaporization occurs due to this boiling, the salt concentration of the aqueous solution 1B increases. That is, the saturation curve of the aqueous solution 1B approaches the saturation curve of calcium chloride hexahydrate. In accordance with this, the saturation temperature of the aqueous solution 1B also rises, so that the temperature detected by the temperature sensor 7 also rises. When the salt concentration of the aqueous solution 1B in the heat storage container 2 decreases until it matches the salt concentration of calcium chloride hexahydrate, the temperature of the aqueous solution 1B in the heat storage container 2 reaches 80 ° C. Therefore, when the pressure in the heat storage container 2 is set to 12.76 kPa, it can be understood that calcium chloride hexahydrate is generated if the temperature detected by the temperature sensor 7 reaches 80 ° C. If concentration of aqueous solution 1B is complete | finished at this time, calcium chloride hexahydrate can be manufactured uniformly and accurately.

  In the above embodiment, the pressure in the heat storage container 2 is set to 12.76 kPa, and the temperature when the concentration of the aqueous solution 1B is finished is 80 ° C. However, other values as shown in Table 1, for example, are used. Even if the combination is used, calcium chloride hexahydrate can be accurately produced.

  As described above, according to the present embodiment, the heat storage hydrate salt can be directly manufactured at the place of use using the heat storage device 10A, and the manufactured heat storage hydrate salt is used as it is as a heat storage material. be able to. For this reason, conventionally, the heat storage hydrate salt produced must be transported to the place of use, whereas in the present invention, the raw material 1A that is lighter than the heat storage hydrate salt may be transported to the place of use.

  Table 2 shows the weight of the raw material 1A with respect to 100 kg of the heat storage hydrate salt for various heat storage hydrate salts. As can be seen from Table 2, if the hydrated salt for heat storage is manufactured using the manufacturing method of the present embodiment, the labor required to transport the heat storage material can be significantly reduced.

  In the present embodiment, in the second step, an aqueous solution is once generated in the heat storage container 2 by supplying an amount of water that can dissolve the entire amount of the raw material 1 </ b> A into the heat storage container 2. In the conventional manufacturing method, the hydration reaction proceeds only on the solid phase so as to move linearly from point A or point B in FIG. 2 to point D. Therefore, even if it is going to manufacture the hydrated salt for thermal storage in the thermal storage container 2, the heater 3 becomes obstructive and a uniform hydration reaction does not occur. On the other hand, as in the present embodiment, once the aqueous solution is formed in the heat storage container 2 in the second step and the aqueous solution is boiled in the third step, the heater 3 is present in the heat storage container 2. A uniform hydration reaction can occur. As a result, a hydrated salt having a desired number of water molecules can be produced with high accuracy.

(Second Embodiment)
Next, with reference to FIG. 4, the manufacturing method of the hydrated salt for thermal storage which concerns on 2nd Embodiment of this invention is demonstrated. In the present embodiment, the heat storage device 10B is used as the manufacturing device. In the present embodiment and each embodiment described later, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The heat storage device 10B includes a heat pump having a refrigerant circuit 8 that circulates the refrigerant. And the heater 3 radiates the heat created by the heat pump.

  Specifically, the refrigerant circuit 8 includes a compressor 81, a radiator 82, an expansion means 83, and an evaporator 84, and these devices 81 to 84 are connected in this order by piping. The heater 3 is constituted by a radiator 82. The expansion means 83 may be an expansion valve or an expander that recovers power from the expanding refrigerant.

  This embodiment is the same as the first embodiment, except that the aqueous solution 1B is heated by the refrigerant in the heater 3 (heat radiator 82) in the third step. Therefore, even if such a heat storage device 10B is used, a hydrated salt having a desired number of water molecules can be accurately produced as in the first embodiment.

  When heat generated by the heat pump is used, a heat medium circuit 9 that passes through the heater 3 and the radiator 82 is provided as in the heat storage device 10C of the modification shown in FIG. By circulating the heat medium in the circuit 9, the heat medium heated by the refrigerant in the radiator 82 may be radiated by the heater 3.

(Third embodiment)
Next, with reference to FIG. 6, the manufacturing method of the hydrated salt for thermal storage which concerns on 3rd Embodiment of this invention is demonstrated. In the present embodiment, the heat storage device 10D is used as the manufacturing device. In this heat storage device 10 </ b> D, a solar heat collector 92 is provided in the heat medium circuit 9 that circulates the heat medium via the heater 3.

  This embodiment is the same as the first embodiment except that the aqueous solution 1B is heated by a heat medium to which solar heat is applied in the third step. Therefore, even if such a heat storage device 10B is used, a hydrated salt having a desired number of water molecules can be accurately produced as in the first embodiment.

(Fourth embodiment)
Next, with reference to FIG. 7, the manufacturing method of the hydrated salt for thermal storage which concerns on 4th Embodiment of this invention is demonstrated. In the present embodiment, the heat storage device 10E is used as the manufacturing device. The heat storage device 10E is provided with a heat exchanger 93 that performs heat exchange between the heat medium circulating in the heat medium circuit 9 via the heater 3 and the second heat medium heated by the combustion device 94. ing. As the combustion device 94, a gas water heater, a fuel cell, a boiler, or the like can be used.

  This embodiment is the same as the first embodiment, except that the aqueous solution 1B is heated using the exhaust heat of the combustion device 94 in the third step. Therefore, even if such a heat storage device 10E is used, a hydrated salt having a desired number of water molecules can be accurately produced as in the first embodiment.

(Other embodiments)
In the embodiment and the modification thereof, as shown in FIG. 8, the heater 35 can be installed in the heat storage container 2. In this way, the aqueous solution 1B can be heated even when the heating capability of the heater 3 is reduced and boiling under reduced pressure does not occur. Therefore, it becomes possible to proceed with the production of the hydrated salt without reducing the hydration reaction.

  Moreover, in the said embodiment and its modification, although heat storage apparatus 10A-10E was used as a manufacturing apparatus, this invention is not limited to this. For example, it is also possible to produce a hydrated salt for heat storage using a container dedicated for production. Moreover, although this invention can manufacture the hydrate salt for thermal storage directly in the place of use, it is useful also when manufacturing the hydrate salt for thermal storage in a factory.

  INDUSTRIAL APPLICATION This invention is useful as a method of manufacturing the hydrated salt for thermal storage used for the thermal storage apparatus utilized for a water heater, an air conditioning facility, a factory waste heat utilization apparatus, etc.

DESCRIPTION OF SYMBOLS 1A Raw material 1B Aqueous solution 2 Heat storage container 3 Heater 4 Outflow pipe 41 Pressure reducing means 42 Regulator 5 Water supply pipe 6 Pressure sensor 7 Temperature sensor 10A to 10E Heat storage device

Claims (6)

A method for producing a hydrated salt for heat storage, comprising:
A first step of filling a container with a raw material having less hydration water than the hydrated salt for heat storage;
A second step of supplying, in the container, water in an amount that is equal to or greater than a mass difference between the hydrated salt for heat storage and the raw material and that can dissolve the total amount of the raw material;
Depressurizing the inside of the vessel to boil the aqueous solution in the vessel, and concentrating the aqueous solution to the salt concentration of the hydrated salt for heat storage;
The manufacturing method of the hydrated salt for thermal storage containing this.   The method for producing a hydrated salt for heat storage according to claim 1, wherein the raw material is entirely solid.   The method for producing a hydrated salt for heat storage according to claim 1 or 2, wherein in the third step, the aqueous solution is boiled by heating the aqueous solution in a state where the inside of the container is decompressed.   The said 3rd process WHEREIN: When the temperature of the aqueous solution in the said container reaches | attains the saturation temperature of the said hydrated salt for thermal storage corresponding to the pressure in the said container, the concentration of the said aqueous solution is complete | finished. A method for producing a hydrated salt for heat storage. The container is a heat storage container for housing a heat storage material in a heat storage device,
The manufacturing method of the hydrated salt for thermal storage of Claim 3 or 4 which heats the said aqueous solution with the heater which should heat the said thermal storage material in the said thermal storage container at a said 3rd process.   The said heater is a manufacturing method of the hydrated salt for thermal storage of Claim 5 which thermally radiates the heat produced with the heat pump.

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