CN105733518A - Integrated energy storage structure, preparation method and application - Google Patents

Abstract

The invention relates to an integrated energy storage structure, which comprises a packaging shell and a phase-change heat storage material packaged inside the packaging shell. The energy storage structure provided by the present invention is an integrated structure composed of an encapsulation shell and a phase-change heat storage material, which not only overcomes the problem of poor heat storage effect of a single heat storage material, but also overcomes the difficulty of storing molten salt heat storage materials, which are easy to store. The problems of leakage and corrosion have fully utilized the advantages of composite materials; and the structure is simple, ensuring the safety and reliability of the heat storage system and good thermal conductivity.

Description

Integrated energy storage structure, preparation method and application

technical field

The invention belongs to the technical field of producing corrosion-leakage coatings of high-temperature heat-resistant heat storage materials by chemical and chemical methods and the field of energy material science, and specifically relates to an integrated energy storage structure, preparation method and application, in particular to a high-temperature composite phase transition An integrated energy storage structure, a preparation method and an application of an integrated package of a heat storage material and an anti-corrosion coating.

Background technique

Improving energy conversion and utilization efficiency is a major issue that must be given priority in the implementation of sustainable development strategy in my country. In many energy utilization systems, there is a contradiction between energy supply and demand mismatch, resulting in irrational energy utilization and a large amount of waste. At present, the discharge of high-temperature flue gas and high-temperature waste heat in industry reaches 57000m ³ /h, and the temperature is 900-1100℃. Long-term emission not only wastes resources, but also causes non-negligible thermal pollution to the atmospheric environment. Recycling and utilizing the above-mentioned high-temperature waste heat can not only solve the thermal pollution of the environment, but also convert it into a usable form of energy, which has important application value and social benefits.

High-temperature phase-change materials, especially metal phase-change materials, have the advantages of high melting point, high heat storage density, approximately isothermal heat absorption/release process, and easy control of the process, which can meet the requirements of recovering high-temperature flue gas and high-temperature waste heat. It is the current heat storage technology research hotspots in the field.

Inorganic salts have great advantages in the application field of high-temperature phase change heat storage, so the current high-temperature heat storage phase change materials use inorganic salts or alloys as the main components. However, the shortcomings of inorganic molten salts in practical applications are also very prominent: molten salts are a very important class of heat storage materials, which have the advantages of high operating temperature, large latent heat, high heat storage density, small degree of supercooling, and low cost. It has received widespread attention at home and abroad. However, molten salt has strong corrosion performance at high temperature, and has high requirements on the anti-corrosion performance of containers. Especially high temperature (above 500°C) molten salt heat storage materials, such as chloride salt, basically corrode all stainless steels. Severely restricts the large-scale application of molten salt heat storage materials, making it difficult to give full play to the advantages of high service temperature, high phase change enthalpy and low cost of chloride salts. Chloride salts are highly corrosive to containers; Large shrinkage and strong corrosion; nitrate has a small heat of fusion, low thermal conductivity, and is prone to local overheating during use. Therefore, it is of great significance to develop integrated heat storage materials and molten salt corrosion-resistant coatings to promote the large-scale use of molten salt heat storage materials.

In order to solve this problem, those skilled in the art often use ceramics as the substrate to load high-temperature phase change heat storage materials, and compound inorganic salts and ceramic substrates. However, during the phase transformation process of molten salts, the liquid phase is easy to leak, especially under high temperature conditions. Salt is highly corrosive and places extremely harsh demands on the containers in which it is contained. US5567346 discloses a heat storage material composed of sodium sulfate, ammonium chloride, sodium bromide and ammonium sulfate as the main raw materials, but the pure inorganic salt requires a large container, which puts forward higher requirements for the thermal insulation and safety of the system ; US5685151 discloses a material for solar heat storage, the main component is sodium chloride, and the container for storing salt used is a special stainless steel material, which is extremely expensive, and after long-term use, there is still corrosion.

Therefore, there is an urgent need to develop a high-temperature phase-change heat storage material in this field, which can solve the defects of easy corrosion of the package and leakage of existing heat storage materials, and has a simple preparation process and low cost.

Contents of the invention

In view of the leakage and corrosion problems of pure inorganic molten salt heat storage materials and molten salt/ceramic composite heat storage materials in the prior art, the present invention provides an integrated energy storage structure, preparation method and application. The integrated energy storage structure is an integrated packaging structure of high-temperature composite heat storage material and anti-corrosion coating, and the preparation method is low-cost and the process is simple.

The present invention solves its technical problem and adopts the following technical solutions:

An integrated energy storage structure, the structure includes an encapsulation shell, and a phase-change heat storage material encapsulated inside the encapsulation shell.

Preferably, the packaging shell of the present invention is graphite dispersed with sodium silicate.

Preferably, the dispersion of sodium silicate in the graphite is 1-10wt%, such as 1.2wt%, 1.5wt%, 1.8wt%, 2.4wt%, 2.8wt%, 3.5wt%, 4.2wt%, 5.5wt% %, 5.7wt%, 6.1wt%, 6.6wt%, 6.8wt%, 7.2wt%, 7.8wt%, 8.4wt%, 8.9wt%, 9.4wt%, etc.

Preferably, the modulus of the sodium silicate is 0.9-1.3, such as 1.0, 1.1, 1.2 and so on.

Preferably, the phase change heat storage material is a mixture of binary molten salt and carrier.

Preferably, the binary molten salt is a combination of any two or more of sodium carbonate, lithium carbonate, potassium carbonate, lithium nitrate, sodium nitrate, barium nitrate, lithium nitrate, and potassium nitrate; preferably sodium carbonate and carbonic acid A combination of lithium, a combination of sodium nitrate and potassium nitrate.

Preferably, the carrier is magnesium oxide or silicon dioxide.

Preferably, the phase change heat storage material is a mixture of sodium carbonate, lithium carbonate and magnesium oxide, preferably the mass ratio of sodium carbonate and lithium carbonate is 4:1 to 1:1, such as 3.5:1, 3.2:1 , 3.0:1, 2.7:1, 2.3:1, 1.8:1, 1.6:1, 1.3:1, etc., the mass ratio of the sum of the quality of sodium carbonate and lithium carbonate to magnesium oxide is 1:2～4: 1, such as 3.5:1, 3.2:1, 3.0:1, 2.7:1, 2.3:1, 1.8:1, 1.6:1, 1.3:1, 1:1.2, 1.2:1, etc.

Preferably, the packaging shell has a thickness of 0.5-3 cm;

Preferably, the diameter or side length of the phase change heat storage material is 1 to 20 times the thickness of the packaging shell.

If the phase-change heat storage material is cylindrical, its diameter is 1-20 times the thickness of the packaging shell; if the phase-change heat storage material is a cuboid, its side length is 1-20 times the thickness of the packaging shell.

The second object of the present invention is to provide a method for preparing the integrated energy storage structure according to the first object, the method comprising the following steps:

(1) Prepare solid phase change heat storage materials;

(2) Prepare solid packaging shell materials;

(3) Lay the packaging shell material on the bottom of the mould, vertically put a baffle inside the mould, the baffle has a certain distance from the side wall, and the baffle and the shell material encapsulated at the bottom form a container;

(4) Add the phase-change heat storage material of step (1) to the interior of the container described in step (3), and add the encapsulation shell material of step (2) to the space between the container and the side wall of the mold described in step (3). ; Then extract the baffle, and spread the encapsulation shell material above the phase change energy storage material in the mold to encapsulate the phase change heat storage material;

(5) Pressurize the inside of the mold, press the phase change heat storage material and the packaging shell material into an integrated structure under pressure, and obtain a molded sample after demoulding;

(6) Sintering the molded sample obtained in step (5) to obtain the integrated energy storage structure according to claim 1 .

Preferably, the holding pressure in step (5) is 5-30 MPa, such as 6 MPa, 10 MPa, 13 MPa, 18 MPa, 22 MPa, 28 MPa, 28 MPa, etc.

Preferably, the holding time is 0.5min to 10min, such as 0.6min, 1min, 1.3min, 1.8min, 2.5min, 2.9min, 3.3min, 4.2min, 4.8min, 5.6min, 7.8min, 9.5min, etc. .

Preferably, the phase change heat storage material in step (1) is a mixture of binary molten salt and carrier.

Preferably, the binary molten salt is a combination of any two or more of sodium carbonate, lithium carbonate, potassium carbonate, lithium nitrate, sodium nitrate, barium nitrate, lithium nitrate, and potassium nitrate; preferably sodium carbonate and carbonic acid A combination of lithium, a combination of sodium nitrate and potassium nitrate.

Preferably, the carrier is magnesium oxide or silicon dioxide.

Preferably, the phase change heat storage material is a mixture of sodium carbonate, lithium carbonate and magnesium oxide, preferably the mass ratio of sodium carbonate and lithium carbonate is 4:1 to 1:1, such as 3.5:1, 3.2:1 , 3.0:1, 2.7:1, 2.3:1, 1.8:1, 1.6:1, 1.3:1, etc., the mass ratio of the sum of the quality of sodium carbonate and lithium carbonate to magnesium oxide is 1:2～4: 1, such as 3.5:1, 3.2:1, 3.0:1, 2.7:1, 2.3:1, 1.8:1, 1.6:1, 1.3:1, 1:1.2, 1.2:1, etc.

Preferably, the method for preparing the solid phase-change heat storage material is mixing grinding, and the grinding process is solvent-free grinding.

Preferably, the process of preparing the solid packaging shell material described in step (2) is: adding sodium silicate solution to graphite.

Preferably, the modulus of the sodium silicate solution is 0.9-1.3, such as 1.0, 1.1, 1.2 and so on.

Preferably, the amount of sodium silicate solution added to the graphite is 0.01 to 0.1 g/g graphite, for example, 0.02 g of sodium silicate solution, 0.03 g of sodium silicate solution, and 0.04 g of sodium silicate solution are added to each gram of graphite , Sodium silicate solution 0.05g, sodium silicate solution 0.06g, sodium silicate solution 0.07g, sodium silicate solution 0.08g or sodium silicate solution 0.09g, etc.

Preferably, the mold in step (3) is cylindrical or cuboid.

Preferably, when the mold is cylindrical, the distance between the baffle and the side wall is 0.1 to 0.3 of the diameter of the bottom surface of the cylinder; when the mold is cuboid, the distance between the baffle and the side wall is corresponding to the cuboid 0.1 to 0.3 of the distance between the two side walls.

Preferably, the thicknesses of the packaging casing material laid flat on the bottom of the mold in step (3) and the packaging casing material laid flat above the phase change energy storage material in the mold in step (4) are each independently 1.1 to 1.3 times the distance between the baffle and the side wall.

The third purpose of the present invention is to provide an integrated energy storage structure as described in the first purpose, which is used for industrial waste heat recovery, solar thermal utilization, and large-scale abandoned wind power utilization for heat storage , high-temperature flue gas recovery, cold-heat-electricity combined system and the synthesis of composite materials.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The energy storage structure provided by the present invention is an integrated structure composed of an encapsulation shell and a phase-change heat storage material, which not only overcomes the problem of poor heat storage effect of a single heat storage material, but also overcomes the difficulty of molten salt heat storage materials. The problems of storage, easy leakage and corrosion give full play to the advantages of composite materials; and the structure is simple, ensuring the safety and reliability of the heat storage system, good thermal conductivity, and the thermal conductivity is above 4.5W/(m K);

(2) The preparation method of the energy storage structure provided by the present invention is to directly encapsulate the phase-change heat storage material (molten salt) and the packaging shell through briquetting to obtain an integrated energy storage structure. The preparation process is simple, and the heat storage material The comprehensive performance including heat storage and heat release efficiency has been greatly improved, and at the same time, the high corrosion performance of molten salt has been solved.

Description of drawings

Fig. 1 has provided the schematic diagram of the perspective structure of the integrated energy storage structure prepared in Example 1;

Figure 2 shows a schematic cross-sectional structure of the integrated energy storage structure prepared in Example 1;

Among them, 1-encapsulation shell, 2-phase change heat storage material.

detailed description

In order to facilitate understanding of the present invention, the present invention enumerates the following examples. It should be clear to those skilled in the art that the embodiments are only for helping to understand the present invention, and should not be regarded as specific limitations on the present invention.

Example 1:

(1) Get 6 grams of sodium carbonate, 6 grams of lithium carbonate and 18 grams of magnesium oxide and mix and grind evenly to be mixed with 30 grams of inorganic salt/ceramic matrix mixture, take by weighing 20 grams of the mixture, as a phase change heat storage material;

(2) Get coating raw material graphite 5 grams, 0.5 gram 0.9 modulus sodium silicate solution and carry out batching, take by weighing 2g as encapsulation shell material;

(3) Take a cylindrical mold with a diameter of 10cm and a height of 5cm, spread 0.5g of the packaging shell material in step (2) evenly on the bottom of the mold, and then put in a baffle with a size smaller than that of the mold, and the baffle is at a distance from the mold The distance between the side walls is 0.5 cm, and the baffle and the shell material encapsulated at the bottom form the container;

(4) Add 20g of the phase-change heat storage material of step (1) to the interior of the container described in step (3), and add 1g of the packaging shell material of step (2) between the baffle plate and the side wall of the mold; then pull out the baffle plate, Then inside the mould, spread the remaining 0.5g packaging shell material above the phase change energy storage material, and encapsulate the phase change heat storage material;

(5) Forming on a hydraulic press, the pressure is 6MPa, and the pressure holding time is 10min, and the molded sample is obtained by demoulding;

(6) Put the molded sample in step (5) into a graphite crucible, sinter and heat to 550°C in an inert atmosphere, keep it warm for 1 hour and then lower it to room temperature to obtain an integrated energy storage structure—corrosion-resistant and leak-proof Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated heat storage material.

The integrated energy storage structure prepared in Example 1 has an encapsulation shell 1 and a phase-change heat storage material 2 encapsulated inside the encapsulation shell 1. The thickness of the shell is 9 cm, and the diameter of the phase-change heat storage material is 4.5cm, 4cm high.

Fig. 1 has provided the schematic diagram of the perspective structure of the integrated energy storage structure prepared in Example 1;

FIG. 2 shows a schematic cross-sectional structure of the integrated energy storage structure prepared in Example 1.

The thermal conductivity of the Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated package heat storage material obtained in Example 1 was tested by a laser thermal conductivity meter (model 427, NETZSCH, Germany) to 4.5 W/(m·K).

Example 2:

(1) Get 8 grams of sodium carbonate, 2 grams of lithium carbonate and 10 grams of magnesium oxide and mix and grind evenly to be prepared into 20 grams of inorganic salt/ceramic matrix mixture, and take 15 grams of the mixture as a phase-change heat storage material;

(2) Get coating raw material graphite 10 grams, 0.05 gram 1.3 modulus sodium silicate solution and carry out batching, take by weighing 5g, as encapsulation shell material;

(3) Take a cylindrical mold with a diameter of 20cm and a height of 10cm, spread 1.25g of the packaging shell material in step (2) evenly on the bottom of the mold, and then put in a baffle whose size is smaller than that of the mould. A distance of 1 cm from the side wall, the baffle and the shell material encapsulated at the bottom form a container;

(4) Add 15g of the phase-change heat storage material of step (1) to the inside of the container described in step (3), and add 2.5g of the packaging shell material of step (2) between the baffle plate and the side wall of the mold; then pull out the baffle plate , and then lay the remaining 1.25g of encapsulation shell material on the top of the phase change energy storage material inside the mould, and encapsulate the phase change heat storage material;

(5) Forming on a hydraulic press, the pressure is 15MPa, the pressure holding time is 2min, and the molded sample is obtained by demoulding;

(6) Put the molded sample in step (5) into a graphite crucible, sinter and heat to 650°C in an inert atmosphere, keep it warm for 30 minutes, and then lower it to room temperature to obtain an integrated energy storage structure—corrosion-resistant and leak-proof Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated heat storage material.

Using the same test method as in Example 1, the thermal conductivity of the obtained Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated heat storage material was tested to be 4.7 W/(m·K).

Example 3:

(1) Get 20 grams of sodium carbonate, 10 grams of sodium carbonate and 7.5 grams of magnesium oxide, mix and grind evenly to be mixed with 37.5 grams of inorganic salt/ceramic matrix mixture, and take 14 grams of the mixture as a phase change heat storage material;

(2) Get 10 grams of coating raw material graphite and 0.1 gram of 1.1 modulus sodium silicate solution to carry out batching, take by weighing 5g, as encapsulation shell material;

(3) Take a cylindrical mold with a diameter of 10cm and a height of 20cm, spread 0.5g of the packaging shell material in step (2) evenly on the bottom of the mold, and then put in a baffle whose size is smaller than that of the mould. The side wall is 3cm away, and the shell material encapsulated by the baffle plate and the bottom forms a container;

(4) Add 14g of the phase-change heat storage material of step (1) to the interior of the container described in step (3), and add 1g of the encapsulation shell material of step (2) between the baffle plate and the side wall of the mold; then pull out the baffle plate, Then inside the mould, spread the remaining 0.5g packaging shell material above the phase change energy storage material, and encapsulate the phase change heat storage material;

(5) Forming on a hydraulic press, the pressure is 30MPa, the pressure holding time is 0.5min, and the molded sample is obtained by demoulding;

(6) Put the molded sample in step (5) into a graphite crucible, sinter and heat to 600°C in an inert atmosphere, keep it warm for 40 minutes, and then lower it to room temperature to obtain an integrated energy storage structure—corrosion-resistant and leak-proof Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated heat storage material.

Using the same test method as in Example 1, the thermal conductivity of the obtained Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated heat storage material was tested to be 4.6 W/(m·K).

Comparative example 1

(1) Get 8 grams of sodium carbonate, 2 grams of lithium carbonate and 10 grams of magnesium oxide and mix and grind evenly to be prepared into 20 grams of inorganic salt/ceramic matrix mixture, and take 15 grams of the mixture as a phase-change heat storage material;

(2) Take a cylindrical mold with a diameter of 20cm and a height of 10cm, add 15g of the phase-change heat storage material in step (1) to the mold, and mold it on a hydraulic press with a pressure of 15MPa and a holding time of 2min, and demould to obtain a molded sample ;

(6) Put the molded sample in step (5) into a graphite crucible, sinter and heat to 650° C. in an inert atmosphere, keep it warm for 30 minutes, and then lower it to room temperature to obtain a heat storage material.

Using the same test method as in Example 1, the thermal conductivity of the obtained heat storage material was tested to be 0.93 W/(m·K).

The Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated encapsulation high-temperature composite phase change heat storage material prepared in Example 1, Example 2 and Example 3, compared with the heat storage material prepared in the comparative example, Na The thermal conductivity of the ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite conduction integrated package high-temperature composite phase change heat storage material is significantly improved, that is, it has better heat conduction, heat storage and heat transfer, and at the same time prevents molten salt leakage.

The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow process can be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (9)

1. an integral type energy storing structure, it is characterised in that described structure includes encapsulating housing, and is encapsulated in the phase-change heat-storage material within described encapsulating housing.

2. structure as claimed in claim 1, it is characterised in that described encapsulating housing is the graphite being dispersed with sodium silicate；

Preferably, in described graphite, the dispersion amount of sodium silicate is 1～10wt%；

Preferably, the modulus of described sodium silicate is 0.9～1.3；

Preferably, described phase-change heat-storage material is the mixture of binary fuse salt and carrier；

Preferably, described binary fuse salt is any 2 kinds or the combination of more than two kinds in sodium carbonate, lithium carbonate, potassium carbonate, lithium nitrate, sodium nitrate, barium nitrate, lithium nitrate, potassium nitrate；The combination of preferred sodium carbonate and the combination of lithium carbonate, sodium nitrate and potassium nitrate；

Preferably, described carrier is magnesium oxide or silicon dioxide；

Preferably, described phase-change heat-storage material is sodium carbonate, lithium carbonate and magnesian mixture, it is preferable that the mass ratio of described sodium carbonate and lithium carbonate is 4:1～1:1, and the quality sum of described sodium carbonate and lithium carbonate and magnesian mass ratio are 1:2～4:1.

3. structure as claimed in claim 1 or 2, it is characterised in that the thickness of described encapsulating housing is 0.5～3cm；

Preferably, the diameter of described phase-change heat-storage material or the length of side are 1～20 times of the thickness of described encapsulating housing.

4. the preparation method of the integral type energy storing structure as described in one of claims 1 to 3, it is characterised in that described method comprises the steps:

(1) phase-change heat-storage material of solid-state is prepared；

(2) the encapsulating housing material of solid-state is prepared；

(3) at mold bottom tiling encapsulating housing material, vertically putting into baffle plate at mould inside, described baffle plate distance sidewall has certain distance and the case material composition vessel of described baffle plate and bottom package；

(4) to the internal phase-change heat-storage material adding step (1) of the described vessel of step (3), the encapsulating housing material of step (2) is added to the space between step (3) described vessel and mould side wall；Extract described baffle plate the encapsulating housing material that tiles above phase-changing energy storage material in described mould afterwards out, in order to encapsulate described phase-change heat-storage material；

(5) pressurizeing to mould inside, phase-change heat-storage material and encapsulating housing material are pressed into integral structure by pressurize, obtain molded samples after the demoulding；

(6) molded samples sintering step (5) obtained obtains the integral type energy storing structure described in claim 1.

5. method as claimed in claim 4, it is characterised in that the pressure of step (5) described pressurize is 5～30MPa；

Preferably, the described dwell time is 0.5min～10min.

6. the method as described in claim 4 or 5, it is characterised in that step (1) described phase-change heat-storage material is the mixture of binary fuse salt and carrier；

Preferably, described binary fuse salt is any 2 kinds or the combination of more than two kinds in sodium carbonate, lithium carbonate, potassium carbonate, lithium nitrate, sodium nitrate, barium nitrate, lithium nitrate, potassium nitrate；The combination of preferred sodium carbonate and the combination of lithium carbonate, sodium nitrate and potassium nitrate；

Preferably, described carrier is magnesium oxide or silicon dioxide；

Preferably, described phase-change heat-storage material is sodium carbonate, lithium carbonate and magnesian mixture, it is preferable that the mass ratio of described sodium carbonate and lithium carbonate is 4:1～1:1, and the quality sum of described sodium carbonate and lithium carbonate and magnesian mass ratio are 1:2～4:1；

Preferably, the method for the phase-change heat-storage material of described preparation solid-state is mixed grinding, and described process of lapping is solvent-free grinding.

7. the method as described in one of claim 4～6, it is characterised in that the process of the encapsulating housing material of the preparation solid-state described in step (2) is: add sodium silicate solution in graphite；

Preferably, the modulus of described sodium silicate solution is 0.9～1.3；

Preferably, the amount of the sodium silicate solution added in described graphite is 0.01～0.1g/g graphite.

8. the method as described in one of claim 4～7, it is characterised in that step (3) described mould is column type or cuboid-type；

Preferably, when mould is column type, distance is column type basal diameter the 0.1～0.3 of described baffle plate distance sidewall；When mould is cuboid-type, distance is corresponding two the sidewall distances of cuboid-type the 0.1～0.3 of described baffle plate distance sidewall；

Preferably, the encapsulating housing material of step (3) described mold bottom tiling and the described thickness tiling encapsulating housing material in described mould above phase-changing energy storage material of step (4) are all each independently 1.1～1.3 times of described baffle plate and sidewall distance.

9. the purposes of the integral type energy storing structure as described in one of claims 1 to 3, it is characterized in that, described integral type energy storing structure is used for the large-scale synthesis field abandoning wind-powered electricity generation utilization, high-temperature flue gas recovery, cold-hot-electricity combined system and composite of industrial afterheat recovery, solar energy heat utilization, heat accumulation.