Hybrid heat storage system, chemical heat storage block, chemical heat storage device, and chemical heat storage and heat release method

Abstract

To provide a novel hybrid heat storage system.SOLUTION: A hybrid heat storage system of the present invention has a chemical heat storage device 10 and a sensible heat storage device 20, heats a heat medium of the sensible heat storage device by a heat source in a heat storage stage, heats a chemical heat storage medium of the chemical heat storage device, generates the steam of a reaction medium having first pressure, supplies the steam of a reaction medium having second pressure to the chemical heat storage medium in a heat radiation stage, and reheats at least a part of the heat medium by using the heat-generated chemical heat storage medium. Here, the second pressure is higher than the first pressure, and a temperature of the heat medium which is reheated by the chemical heat storage medium in the heat radiation stage is higher than a temperature of the heat medium which is heated by the heat source in the heat storage stage.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hybrid heat storage system, a chemical heat storage block, a chemical heat storage device using this chemical heat storage block, and a chemical heat storage and heat release method using this chemical heat storage device.

Background Art

[0002] Various heat storage devices are used as energy storage means.

[0003] As such heat storage devices, chemical heat storage devices and sensible heat storage devices are known.

[0004] Chemical heat storage devices can store high-temperature thermal energy, and by adjusting the reaction pressure, a chemical heat pump operation can be performed in which the temperature of the generated heat is higher than the temperature of the stored heat. Since the quality (exergy) of energy is higher at higher temperatures and the thermodynamic value is higher, chemical heat storage devices are preferable from these viewpoints. On the other hand, chemical heat storage devices have a problem of high cost because of their complex configuration.

[0005] Sensible heat storage devices have a low cost because of their simple configuration. On the other hand, sensible heat storage devices have a problem that it is difficult to accumulate and hold high-temperature thermal energy in terms of heat resistance and heat insulation of the container.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention provides a hybrid heat storage system that solves the problems of the above-described conventional chemical heat storage devices and sensible heat storage devices. Further, the present invention provides a chemical heat storage block that can perform efficient chemical heat storage when used in a chemical heat storage device, particularly when used in the hybrid heat storage system of the present invention. Further, the present invention relates to a chemical heat storage device using this chemical heat storage block, and a chemical heat storage and heat release method using this chemical heat storage device.

Means for Solving the Problems

[0007] Examples of the present invention include the following examples.

[0008] <Aspect 1> A hybrid heat storage system having a chemical heat storage device and a sensible heat storage device, In the heat storage stage, a heat medium of the sensible heat storage device is heated by a heat source to obtain the heated heat medium, and at least a part of the heated heat medium is used to heat a chemical heat storage medium of the chemical heat storage device to cause an endothermic reaction, separate and remove a reaction medium from the chemical heat storage medium to generate the chemical heat storage medium from which the reaction medium has been removed and steam of the reaction medium at a first pressure, and store the heat medium that has been heated by the chemical heat storage medium and has become low temperature in the sensible heat storage device, In the heat release stage, steam of the reaction medium at a second pressure is supplied to the chemical heat storage medium of the chemical heat storage device to cause an exothermic reaction with the chemical heat storage medium, and at least a part of the heat medium stored in the sensible heat storage device is reheated by the exothermic chemical heat storage medium to obtain the reheated heat medium, The second pressure is higher than the first pressure, and The temperature of the heat medium reheated by the chemical heat storage medium in the heat release stage is higher than the temperature of the heat medium heated by the heat source in the heat storage stage, Hybrid heat storage system. <Aspect 2> Further having a steam turbine, and Steam of the reaction medium at the first pressure generated in the heat storage stage is supplied to the steam turbine to generate electricity. The system according to Aspect 1. <Aspect 3> Further having a heat exchanger, and In the heat storage stage, at least a part of the heat medium whose temperature has decreased by heating the chemical heat storage medium of the chemical heat storage device is reheated by heat exchange with the heat medium from the heat source in the heat exchanger to obtain the reheated heat medium, and the reheated heat medium is stored in the sensible heat storage device. The system according to aspect 1 or 2. 〈Aspect 4〉 The system according to any one of aspects 1 to 3, wherein the sensible heat storage device is a thermocline heat storage device. 〈Aspect 5〉 The system according to any one of aspects 1 to 4, wherein the chemical heat storage medium is calcium hydroxide and the reaction medium is water. 〈Aspect 6〉 Having a porous substrate having communication pores and a chemical heat storage medium filled in the communication pores of the porous substrate. The chemical heat storage medium generates heat when reacting with the reaction medium and absorbs heat when separated from the reaction medium, and The porous substrate has a through-flow path for allowing the vapor of the reaction medium to flow through. Chemical heat storage block. 〈Aspect 7〉 A double-tube container having an inner flow path and an outer flow path, and One or a plurality of chemical heat storage blocks according to aspect 6 disposed in the inner flow path. Having The heat medium is circulated through the outer flow path, In the inner flow path, the vapor of the reaction medium is allowed to flow through the through-flow path of the chemical heat storage block and between the inner wall of the inner flow path and the chemical heat storage block. Chemical heat storage device. 〈Aspect 8〉 The chemical heat storage device according to aspect 7, wherein a plurality of the inner flow paths are disposed in one outer flow path. 〈Aspect 9〉 A chemical heat storage and heat release method using the chemical heat storage device according to aspect 7 or 8, comprising In the heat storage stage, the heat medium is circulated through the outer flow path, thereby heating the chemical heat storage medium of the chemical heat storage block to remove the reaction medium, and generating steam of the chemical heat storage block from which the reaction medium has been removed and the reaction medium at the first pressure. In the heat release stage, the heat medium is circulated through the outer flow path, and the steam of the reaction medium at the second pressure is circulated through the inner flow path to cause the chemical heat storage block to generate heat. The heated heat medium is obtained by reheating the heat medium supplied to the outer flow path by the heated chemical heat storage block. The second pressure is higher than the first pressure, and the temperature of the heat medium reheated by the chemical heat storage medium in the heat release stage is higher than the temperature of the heat medium for heating the chemical heat storage medium in the heat storage stage. Chemical heat storage and heat release method.

Advantages of the Invention

[0009] According to the hybrid heat storage system of the present invention, the problems of conventional chemical heat storage devices and sensible heat storage devices can be solved. Further, the chemical heat storage block of the present invention can perform efficient chemical heat storage when used in a chemical heat storage device, and can be particularly used in the hybrid heat storage system of the present invention.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described based on specific aspects with reference to the drawings, but the present invention is not limited to these aspects. Also, the drawings are for illustrative purposes and do not represent the ratio of actual dimensions.

[0012] 《Hybrid Heat Storage System》 Hereinafter, the hybrid heat storage system of the present invention will be particularly described based on an aspect in which calcium hydroxide (or calcium oxide) and water are used as the chemical heat storage medium and the reaction medium of the chemical heat storage device, respectively, and a thermocline heat storage device is used as the sensible heat storage device. However, of course, in the hybrid heat storage system of the present invention, other combinations of chemical heat storage media and reaction media, and other sensible heat storage devices can also be used.

[0013] 〈First Aspect〉 As shown with reference to FIG. 1, the first aspect of the hybrid heat storage system of the present invention includes a chemical heat storage device and a sensible heat storage device. Note that the temperatures shown in FIG. 1 are examples of the temperatures when operating the hybrid heat storage system of the present invention, and do not necessarily indicate the actual temperatures.

[0014] (Heat storage stage) In the heat storage stage of this hybrid heat storage system, as shown with reference to FIG. 1(a), a heat source (30) heats the heat medium of the sensible heat storage device (20) to obtain a heated heat medium. At least a part of the heated heat medium is supplied to the chemical heat storage device (10) via a branch valve (91), whereby the chemical heat storage medium (Ca(OH)2) of the chemical heat storage device (10) is heated to cause an endothermic reaction. By this endothermic reaction, water (H2O) as a reaction medium is separated and removed from the chemical heat storage medium (Ca(OH)2), generating a chemical heat storage medium (CaO) from which the reaction medium (H2O) has been removed and steam (H2O) of the reaction medium at a first pressure. Also, the heat medium that has become low temperature by heating the chemical heat storage medium (Ca(OH)2) is stored in the sensible heat storage device (20). The steam (H2O) of the reaction medium at the first pressure can optionally be cooled by heat exchange with cooling water and stored as a liquid in the reaction medium storage section (50). At this time, the heat medium discharged from the low temperature side of the sensible heat storage device (20) can be supplied to the heat source (30) via a branch valve (92), whereby it can be heated by the heat source (30).

[0015] In FIG. 1(a), the dotted line indicates a flow path that is not used in the heat storage stage. However, although not shown in FIG. 1(a), naturally, the heat of the heat source (30) can be used not only for heat storage but also in heat utilization facilities (40) such as power generation facilities.

[0016] (Heat release stage) In the heat dissipation stage of this hybrid heat storage system, as shown with reference to Fig. 1(b), steam of the reaction medium (H2O) at a second pressure is supplied to the chemical heat storage medium (CaO) of the chemical heat storage device (10) to cause an exothermic reaction with the chemical heat storage medium (CaO). Further, at least a part of the heat medium stored in the sensible heat storage device (20) is reheated by the chemical heat storage medium that has generated heat thereby, to obtain a reheated heat medium.

[0017] Here, the second pressure, that is, the pressure when supplying steam of the reaction medium (H2O) to the chemical heat storage medium (CaO) of the chemical heat storage device (10) in the heat dissipation stage, is higher than the first pressure, that is, the pressure when separating and removing the reaction medium (H2O) from the chemical heat storage medium (Ca(OH)2) of the chemical heat storage device (10) in the heat storage stage. Specifically, the second pressure may be 1.1 times or more, 1.3 times or more, 1.5 times or more, 2.0 times or more, 3.0 times or more, 4.0 times or more, or 5.0 times or more of the first pressure, and may also be 20.0 times or less, 10.0 times or less, 8.0 times or less, 6.0 times or less, or 5.0 times or less.

[0018] In this way, by making the second pressure higher than the first pressure, the temperature of the heat medium reheated by the chemical heat storage medium in the heat dissipation stage can be made higher than the temperature of the heat medium heated by the heat source in the heat storage stage. Specifically, this temperature difference may be 1°C or more, 3°C or more, 5°C or more, or 10°C or more, and may also be 200°C or less, 150°C or less, 100°C or less, 50°C or less, 30°C or less, 20°C or less, or 10°C or less.

[0019] This is because in the reaction of separating and removing the reaction medium from the chemical heat storage medium by an endothermic reaction to generate the chemical heat storage medium from which the reaction medium has been removed and steam of the reaction medium, for example, in the reaction of decomposition of calcium hydroxide shown below, when the reaction pressure increases, the equilibrium shifts to the left side (exothermic reaction side), and when the reaction temperature increases, the equilibrium shifts to the right side (endothermic reaction side). Therefore, when the reaction pressure is high, the thermodynamic equilibrium temperature becomes high: Ca(OH)2 (solid) + endothermic → CaO (solid) + H2O (gas)

[0020] Specifically, in the reaction of the decomposition of calcium hydroxide shown above, the thermodynamic equilibrium temperature is about 507°C at a steam pressure of 0.1 MPa (1.0 atm), whereas the thermodynamic equilibrium temperature becomes about 600°C at a steam pressure of 0.47 MPa (4.7 atm).

[0021] The high-temperature heat obtained in the heat release stage can be optionally used in heat utilization equipment (40) such as power generation equipment.

[0022] In addition, in Fig. 1(b), the dotted line indicates a flow path that is not used in the heat storage stage.

[0023] According to such a hybrid heat storage system of the present invention, the storage of low-temperature thermal energy is performed by a low-cost sensible heat storage device, and the storage of high-temperature thermal energy is performed by a chemical heat storage device. Thus, in the heat release stage, heat output at a temperature higher than the heat storage temperature can be performed by chemical heat pump operation.

[0024] As the sensible heat storage device that can be used in the present invention, a molten salt heat storage device can be used. Therefore, molten salt can be used as the heat medium. Examples of the sensible heat storage device include, in particular, a thermocline heat storage (temperature stratification type sensible heat storage) device, a direct or indirect two-tank heat storage device using a tank for a low-temperature heat medium and a tank for a high-temperature heat medium, and the like.

[0025] Examples of the molten salt that can be used include carbonate-based molten salts, chloride-based molten salts, nitrate-based molten salts, and fluoride-based molten salts.

[0026] Specifically, examples of carbonate-based molten salts include those containing lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, or any combination thereof. Examples of chloride-based molten salts include those containing lithium chloride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, barium chloride, zinc chloride, or any combination thereof. Examples of nitrate-based molten salts include those containing lithium nitrate, sodium nitrate, potassium nitrate, magnesium nitrate, calcium nitrate, barium nitrate, or any combination thereof. Examples of fluoride molten salts include those containing lithium fluoride, sodium fluoride, potassium fluoride, magnesium fluoride, calcium fluoride, barium fluoride, or any combination thereof.

[0027] In addition, examples of combinations of the chemical heat storage medium and the reaction medium that can be used in the present invention include combinations of metal hydroxides (and metal oxides) and water, or combinations of metal salt hydrates (and metal salt anhydrides) and water.

[0028] Specifically, the combination of metal hydroxides (and metal oxides) and water may be a combination of calcium hydroxide (and calcium oxide) and water, a combination of magnesium hydroxide (and magnesium oxide) and water, a combination of strontium hydroxide (and strontium oxide) and water, or a combination of barium hydroxide (and barium oxide) and water.

[0029] In addition, the combination of metal salt hydrates and metal salt anhydrides and water may be a combination of calcium sulfate hydrate (and anhydrous calcium sulfate) and water, or a combination of calcium chloride hydrate (and anhydrous calcium chloride) and water.

[0030] The reaction equations between the above chemical heat storage medium and reaction medium are specifically as follows. Ca(OH)2 (solid) + endothermic → CaO (solid) + H2O (gas) Mg(OH)2(solid) + Endothermic → MgO(solid) + H2O(gas) Sr(OH)2(solid) + Endothermic → SrO(solid) + H2O(gas) Ba(OH)2(solid) + Endothermic → BaO(solid) + H2O(gas) CaSO4·0.5H2O(solid) + Endothermic → CaSO4(solid) + 0.5H2O(gas) CaCl2·0.5H2O(solid) + Endothermic → CaCl2(solid) + 0.5H2O(gas)

[0031] <Second Aspect> The second aspect of the hybrid heat storage system of the present invention further includes a steam turbine (60) and a heat exchanger (70) in addition to the equipment of the first aspect.

[0032] In this hybrid heat storage system, in the heat storage stage, the steam (H2O) of the reaction medium at the generated first pressure is supplied to the steam turbine (60) to generate electricity. According to this, the energy of the steam of the reaction medium at the generated first pressure can be efficiently utilized by converting it into electric power.

[0033] Also, in this hybrid heat storage system, in the heat storage stage, at least a part of the heat medium whose temperature has decreased by heating the chemical heat storage medium (Ca(OH)2) of the chemical heat storage device (10) is heat-exchanged with the heat medium from the heat source (30) in the heat exchanger (70) to be reheated, and the reheated heat medium is obtained and stored in the sensible heat storage device (20). According to this, the temperature of the heat medium stored in the sensible heat storage device (20) can be increased, and thereby the amount of energy stored in the sensible heat storage device (20) can be increased.

[0034] 《Chemical Heat Storage Block》 As shown with reference to FIG. 3, the chemical heat storage block (110) of the present invention has a porous base material (111) having communicating pores and a chemical heat storage medium filled in the communicating pores of the porous base material, and the porous base material (111) has a through-flow path (112) for allowing the vapor of the reaction medium to flow through. Here, the chemical heat storage medium generates heat when reacting with the reaction medium and absorbs heat when separated from the reaction medium.

[0035] Here, the cross-sectional area of this through-flow path can be arbitrarily determined according to the air permeability of the porous base material to be used, the type and amount of the chemical heat storage medium, the intended vapor flow rate, etc. For example, when looking at the cross-section perpendicular to the flow path of the through-flow path, it may be 1% or more, 2% or more, 3% or more, 4% or more, or 5% or more of the porous base material, and may also be 30% or less, 20% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, or 5% or less of the porous base material. Also, as shown with reference to FIG. 4, the chemical heat storage block (120) of the present invention can also have two or more through-flow paths (122).

[0036] According to such chemical heat storage blocks (110, 120) of the present invention, since the chemical heat storage medium is filled in the communicating pores of the porous base material and the porous base materials (111, 121) have through-flow paths (112, 122) for allowing the vapor of the reaction medium to flow through, the separation and reaction between the chemical heat storage medium and the vapor of the reaction medium can be efficiently carried out.

[0037] Moreover, in particular, according to such chemical heat storage blocks of the present invention, efficient operation of the chemical heat storage device, particularly chemical heat pump operation of the chemical heat storage device, can be enabled. Also, according to the chemical heat storage device using such chemical heat storage blocks of the present invention, by increasing the reaction pressure during heat dissipation, a chemical heat pump operation that outputs a temperature higher than the heat storage temperature can be performed.

[0038] In such a chemical heat storage block of the present invention, as the porous substrate, a porous substrate containing a substance selected from the group consisting of silicon oxide, silicon carbide, aluminum nitride, boron nitride, magnesium oxide, aluminum oxide, beryllium oxide, and mixtures thereof can be used. The porous substrate may be, for example, a foamed structure.

[0039] In the chemical heat storage block of the present invention, as the combination of the chemical heat storage medium and the reaction medium, the combination described with respect to the hybrid heat storage system of the present invention can be used.

[0040] In the production of the chemical heat storage block of the present invention, a slurry containing a powder of the chemical heat storage medium can be coated on the porous substrate as described above, dried, and fired as necessary.

[0041] Specifically, for example, when calcium hydroxide (or calcium oxide) is used as the chemical heat storage medium, limestone is fired in a reaction kettle to obtain calcium oxide, water is added to the obtained calcium oxide for a hydration reaction to obtain a calcium hydroxide slurry, this calcium hydroxide slurry is dehydrated by a pressure filter to increase the solid content concentration, a dispersant is added to the obtained calcium hydroxide slurry, water is appropriately added to adjust the solid content concentration, and a calcium hydroxide slurry is obtained.

[0042] Thereafter, this calcium hydroxide slurry is vacuum-impregnated and coated on a porous material as a supporting substrate. Here, the vacuum impregnation can be performed by putting the supporting substrate coated with the calcium hydroxide slurry into a desiccator, reducing the pressure with a vacuum pump, and impregnating the supporting substrate with the calcium hydroxide slurry. Thereafter, the supporting substrate impregnated with the calcium hydroxide slurry is put into an oven and dried to obtain the chemical heat storage block of the present invention.

[0043] The photograph in Fig. 5 shows a silicon carbide-based porous substrate (left in the photograph) and the chemical heat storage block of the present invention manufactured as described above using this silicon carbide-based porous substrate (right in the photograph).

[0044] In FIGS. 3 to 5, a cylindrical chemical heat storage block is shown as the chemical heat storage block of the present invention. However, the chemical heat storage block of the invention is not naturally limited to a cylindrical shape. Therefore, the chemical heat storage block of the present invention may have other shapes, for example, a quadrangular prism shape or a hexagonal prism shape. The fact that the chemical heat storage block of the present invention is a quadrangular prism or a hexagonal prism is preferable for densely filling and arranging a plurality of chemical heat storage blocks.

[0045] The chemical heat storage block of the present invention can be used in a chemical heat storage device.

[0046] 《Chemical Heat Storage Device》 As shown in FIG. 6, the chemical heat storage device (200) of the present invention using the chemical heat storage block (110) of the present invention includes a double-tube container having an inner flow path (210) and an outer flow path (220), and one or a plurality of the chemical heat storage blocks (110) of the present invention arranged in the inner flow path (210). It has.

[0047] In such a chemical heat storage device (200), as shown by the black arrow, a heat medium is circulated through the outer flow path (220), as shown by the white arrow, in the inner flow path (210), the vapor of the reaction medium is circulated through the through-flow path (112) of the chemical heat storage block (110) and between the inner wall of the inner flow path (210) and the chemical heat storage block (110).

[0048] In such a chemical heat storage device (200), the separation and reaction of the chemical heat storage medium and the reaction medium of the chemical heat storage block (110) are promoted, and the heat exchange between the heat medium and the chemical heat storage block (110) is promoted. Therefore, chemical heat storage can be performed efficiently. Further, in such a chemical heat storage device (200), the required heat storage capacity can be easily achieved by changing the number of the chemical heat storage blocks (110).

[0049] In FIG. 6, the distance between the inner wall of the inner flow path (210) and the chemical heat storage block (110) is shown to be relatively wide for the purpose of explanation. However, in reality, it is preferable that this distance be narrow in order to promote heat exchange between the heat medium in the outer flow path and the chemical heat storage block.

[0050] Also, in FIG. 6, as the chemical heat storage device of the present invention, a cylindrical chemical heat storage device having a cylindrical chemical heat storage block is shown. However, as described above, the chemical heat storage block of the invention is not limited to a cylindrical shape. Therefore, the chemical heat storage device of the present invention may be another chemical heat storage device having another shape of chemical heat storage block, for example, a prismatic chemical heat storage device having a prismatic chemical heat storage block with a square cross-section, or a hexagonal prismatic chemical heat storage device having a hexagonal prismatic chemical heat storage block.

[0051] Further, for example, as shown in FIG. 7, in the chemical heat storage device (300) of the present invention, a plurality of inner flow paths (310) may be arranged within one outer flow path (320). Here, as indicated by the black arrow, a heat medium is circulated through the outer flow path (320), and as indicated by the white arrow, vapor of the reaction medium is circulated through the inner flow path (310). In this case, by changing the number of inner flow paths (310) arranged in the outer flow path (320), the required heat storage capacity can be easily achieved.

[0052] In addition, when a plurality of inner channels are arranged within one outer channel, the number of inner channels and the shape of the outer channel can be arbitrarily determined. Therefore, for example, as shown in Fig. 8(a), in a chemical heat storage device (400) where 12 inner channels (410) are arranged within a quadrangular outer channel (420), as shown in Fig. 8(b), in a chemical heat storage device (500) where 7 inner channels (510) are arranged within a circular outer channel (520), as shown in Fig. 8(c), in a chemical heat storage device (600) where 7 inner channels (610) are arranged within a hexagonal outer channel (620), as shown in Fig. 8(d), in a chemical heat storage device (700) where 12 inner channels (710) are arranged within a quadrangular outer channel (720), and as shown in Fig. 8(e), in a chemical heat storage device (800) where 7 inner channels (810) are arranged within a hexagonal outer channel (820) can be implemented.

[0053] Note that in Figs. 8(a) to 8(c), cylindrical heat storage blocks are respectively arranged within quadrangular, circular, and hexagonal outer channels, while in Fig. 8(d), a quadrangular heat storage block is arranged within a quadrangular outer channel, and in Fig. 8(e), a hexagonal heat storage block is arranged within a hexagonal outer channel.

[0054] 《Chemical Heat Storage and Heat Release Method》 In the chemical heat storage and heat release method of the present invention, the chemical heat storage device of the present invention is used.

[0055] As shown with reference to Fig. 9(a), in the heat storage stage of this method, as indicated by the black arrow, a heat medium is circulated through the outer channel (220), thereby heating the chemical heat storage medium of the chemical heat storage block (110) to remove the reaction medium, generating a chemical heat storage block (110) from which the reaction medium has been removed and vapor of the reaction medium at the first pressure, and as indicated by the white arrow, taking out the vapor of this reaction medium.

[0056] Further, as shown with reference to FIG. 9(b), in the heat dissipation stage of this method, a heat medium is circulated through the outer flow path (220), and steam of a reaction medium at a second pressure is circulated through the inner flow path (210) to cause the chemical heat storage block (110) to generate heat. The heated chemical heat storage block (110) reheats the heat medium supplied to the outer flow path as indicated by the black arrow to obtain a reheated heat medium.

[0057] Here, the second pressure, i.e., the pressure of the steam of the reaction medium circulated through the inner flow path in the heat dissipation stage, is higher than the first pressure, i.e., the pressure of the reaction medium removed from the chemical heat storage medium in the heat storage stage. By setting the second pressure higher than the first pressure in this way, the temperature of the heat medium reheated by the chemical heat storage medium in the heat dissipation stage can be made higher than the temperature of the heat medium that heats the chemical heat storage medium in the heat storage stage.

[0058] Regarding the relationship between the second pressure and the first pressure, the difference between the temperature of the heat medium reheated by the chemical heat storage medium in the heat dissipation stage and the temperature of the heat medium that heats the chemical heat storage medium in the heat storage stage, the relationship between the pressure and the thermodynamic equilibrium temperature, etc., reference can be made to the description regarding the hybrid heat storage system of the present invention.

Example

[0059] Using the chemical heat storage device as shown in FIG. 6, a chemical heat storage and heat dissipation method was implemented.

[0060] Specifically, a slurry containing calcium hydroxide was coated on a cylindrical silicon carbide foam structure (diameter 55 mm, height 50 mm) having a through hole at the axial center, and dried to obtain a chemical heat storage block as shown in FIGS. 3 and 5. Twenty of the thus obtained chemical heat storage blocks were stacked and placed in the inner flow path of a vertically placed stainless steel double tube container as shown in FIG. 6. The total amount of calcium hydroxide in the double tube container was about 1.7 kg.

[0061] In the heat storage stage, molten salt at 550 °C was circulated through the outer flow path of the double-pipe container from top to bottom for 400 minutes to decompose calcium hydroxide in the chemical heat storage block into calcium oxide and water vapor (about 0.01 MPa (about 10 kPa)), and water was recovered. From the amount of recovered water after the completion of the heat storage stage, the reaction conversion rate from calcium hydroxide to calcium oxide was estimated to be about 77%.

[0062] In the heat release stage, steam at 0.76 MPa (760 kPa) was circulated through the inner flow path of the double-pipe container with an initial temperature of 400 °C from bottom to top to initiate an exothermic reaction. Here, this steam was made to flow around the chemical heat storage block and through the through-flow path in the inner flow path of the double-pipe container.

[0063] After the start of the reaction, the pressure decreased to 0.5 MPa, but recovered to the initial pressure after about 30 minutes. At almost the same timing when the pressure reached its maximum during the pressure recovery process, the highest temperature of 630 °C, which almost coincides with the equilibrium temperature corresponding to this maximum pressure, was observed.

[0064] The temperature and the steam pressure in the inner flow path of the double-pipe container between the first and the second chemical heat storage blocks from the bottom in the heat release stage are shown in Fig. 10.

Explanation of symbols

[0065] 10 Chemical heat storage device 20 Sensible heat storage device 30 Heat source 40 Heat utilization equipment 50 Reaction medium storage section 60 Steam turbine 70 Heat exchanger 91, 92 Branch valve 110, 120 Chemical heat storage block 111, 121 Porous substrate 112, 122 Through-flow path 200, 300, 400, 500, 600, 700, 800 Chemical heat storage device Inner flow paths 210, 310, 410, 510, 610, 710, 810 Outer flow paths 220, 320, 420, 520, 620, 720, 820

Claims

1. A hybrid heat storage system having a chemical heat storage device and a sensible heat storage device, In the heat storage stage, a heat medium of the sensible heat storage device is heated by a heat source to obtain the heated heat medium, and at least a part of the heated heat medium is used to heat a chemical heat storage medium of the chemical heat storage device to cause an endothermic reaction, separating and removing a reaction medium from the chemical heat storage medium to generate the chemical heat storage medium from which the reaction medium has been removed and vapor of the reaction medium at a first pressure, and storing the heat medium that has been heated by the chemical heat storage medium and has become low temperature in the sensible heat storage device, In the heat release stage, vapor of the reaction medium at a second pressure is supplied to the chemical heat storage medium of the chemical heat storage device to cause an exothermic reaction with the chemical heat storage medium, and at least a part of the heat medium stored in the sensible heat storage device is reheated by the exothermic chemical heat storage medium to obtain the reheated heat medium, The second pressure is higher than the first pressure, In the heat release stage, the temperature of the heat medium reheated by the chemical heat storage medium is higher than the temperature of the heat medium heated by the heat source in the heat storage stage, Further comprising a heat exchanger, and In the heat storage stage, at least a part of the heat medium whose temperature has decreased by heating the chemical heat storage medium of the chemical heat storage device is heat-exchanged with the heat medium from the heat source in the heat exchanger and reheated to obtain the reheated heat medium, and the reheated heat medium is stored in the sensible heat storage device, A hybrid heat storage system.

2. Further comprising a steam turbine, and In the heat storage stage, the vapor of the reaction medium at the first pressure generated is supplied to the steam turbine to generate electricity, The system according to Claim 1.

3. The system according to Claim 1 or 2, wherein the sensible heat storage device is a thermocline heat storage device.

4. The system according to any one of Claims 1 to 3, wherein the chemical heat storage medium is calcium hydroxide and the reaction medium is water.

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