Solid heat storage equipment with high heat storage temperature

Abstract

The solid heat storage equipment with the high heat storage temperature comprises a heat storage body and a heat preservation mechanism, the heat storage body comprises heat storage bricks and an electric heating wire assembly, the electric heating wire assembly comprises a connecting plate and a spiral electric heating wire connected to the connecting plate, and the heat preservation mechanism comprises a side wall, a top wall and a concrete foundation. The side walls and the top wall each comprise an outer heat preservation layer, an inner heat preservation layer and a phase change heat storage module located between the outer heat preservation layer and the inner heat preservation layer. The phase change heat storage module comprises a phase change heat storage module shell, a heat preservation layer heat exchange pipe is installed in the phase change heat storage module shell, and the phase change heat storage module shell is filled with a phase change heat storage material. The inner heat preservation layer is an aluminum silicate fiber module. And a foundation layer heat exchange pipe is pre-buried in the concrete foundation. By improving the heating wire material, the heat preservation measure, the heat accumulator structure and the like, the problems that the heating wire is poor in temperature resistance and short in service life in the high-temperature environment, the external heat preservation measure is difficult to meet the requirement, and the heat accumulator is prone to deformation are solved.

Description

Technical Field

[0001] This invention relates to a solid heat storage device, and more particularly to a solid heat storage device with a high heat storage temperature (e.g., a heat storage temperature of 1000°C). Background Technology

[0002] Currently, the heat storage temperature of existing solid thermal energy storage equipment is generally below 800℃. With the changing demands for high-temperature, high-pressure steam (e.g., 530℃ / 25MPa steam), higher requirements are being placed on the heat storage temperature, such as reaching 1000℃. Achieving this temperature presents several challenges in existing equipment manufacturing technologies and processes. First, while the iron-based high-temperature alloy (e.g., 0Cr25Al5, 0Cr27Al7Mo2) heating wires in existing solid thermal energy storage equipment can operate normally at around 1200℃ (the heating wire temperature reaches 1150℃~1250℃ when the heat storage body temperature reaches 1000℃), their lifespan is significantly shortened, failing to meet normal equipment usage and maintenance cycles. Second, at 1000℃, the heat storage body experiences significant expansion, making it prone to deformation and damage. Third, at 1200℃, the spiral heating wire is prone to creeping, bulging out of the heat storage body, leading to short circuits between heating wire layers and equipment malfunction. Fourth, because the heating wire is supplied with 10KV or 35KV high-voltage electricity, contact measurement cannot be used, and there is a large temperature difference between the outer surface and the interior of the heat storage body. Therefore, when the heat storage temperature reaches 1000℃, it is difficult to detect the temperature of the heating wire and the heat storage body. Fifth, when the heat storage temperature reaches 1000℃, existing external insulation measures are difficult to meet the requirements. First, the external insulation material needs to be an expensive material that can withstand temperatures of 1200℃. Second, using existing insulation measures, the insulation loss reaches 3%-5% at a heat storage body temperature of 800℃, and the insulation loss is even greater at a temperature of 1000℃. Therefore, special insulation measures must be taken. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a solid heat storage device with a high heat storage temperature. By improving the heating wire material, insulation measures and heat storage body structure, this invention solves the problems of poor temperature resistance and short service life of heating wire in high-temperature environments, difficulty in meeting the requirements of external insulation measures, easy deformation of the heat storage body, easy creep of spiral heating wire leading to short circuit between heating wires, and difficulty in detecting the temperature of the heat storage body.

[0004] The technical solution of the present invention is as follows: A high-temperature solid heat storage device includes a heat storage body and an insulation mechanism. The heat storage body includes heat storage bricks and a heating wire assembly. The heating wire assembly includes a connecting plate and a spiral heating wire connected to the connecting plate. The insulation mechanism includes side walls, a top wall, and a concrete foundation. The side walls and top wall each include an outer insulation layer, an inner insulation layer, and a phase change heat storage module located between the outer and inner insulation layers. The phase change heat storage module includes a phase change heat storage module shell. The phase change heat storage module shell is equipped with heat exchange tubes for the insulation layer and filled with phase change heat storage material. The inner insulation layer is an aluminum silicate fiber module. A foundation layer heat exchange tube is pre-embedded inside the concrete foundation.

[0005] Preferably, the heat storage brick has a thermocouple socket; the solid heat storage device includes a corundum thermocouple that passes through the side wall into the thermocouple socket and is used to detect the temperature of the heat storage body.

[0006] Preferably, the solid heat storage device includes an infrared temperature sensor for detecting the temperature of the spiral heating wire; the infrared temperature sensor extends from the side wall into the internal space of the heat preservation mechanism, and a high-purity quartz glass lens is installed at its inner end.

[0007] Preferably, the two ends of the heat exchange tube in the insulation layer serve as the inlet and outlet ends of the tube-side medium, respectively, passing through the shell of the phase change heat storage module and connecting to the manifold; the two ends of the heat exchange tube in the foundation layer serve as the inlet and outlet ends of the tube-side medium, respectively, passing through the concrete foundation and connecting to the manifold.

[0008] Preferably, the aluminum silicate fiber module is a high-purity aluminum silicate fiber insulation module, wherein Al2O3 ≥ 47%; Al2O3 + SiO2 ≥ 99%.

[0009] Preferably, the heat storage brick has a convex-concave structure on its upper and lower surfaces that interlock with each other; in the horizontal direction, an expansion joint is left between adjacent heat storage bricks.

[0010] Preferably, the connecting plate is fixed to the heat storage brick at the end of the heat storage body by fixing bolts.

[0011] Preferably, the phase change thermal storage material is composed of magnesium sulfate heptahydrate, sodium dihydrogen phosphate dihydrate, nucleating agent and thickener.

[0012] Preferably, the spiral heating wire is made of 0Cr27Al7Mo2NbY material; the 0Cr27Al7Mo2NbY material is made from the following raw materials in the following weight percentages: chromium: 28.0~30.0%, aluminum: 8.0%~10.0%, molybdenum: 1.5%~2.5%, carbon ≤ 0.08%, silicon ≤ 1.0%, manganese ≤ 1.0%, phosphorus ≤ 0.03%, sulfur ≤ 0.030%, yttrium: 0.07%~0.13%, niobium: 0.20%~0.40%, titanium: 0.70%~0.90%, with the balance being iron and unavoidable impurity elements; the unavoidable impurity elements have a weight percentage of ≤0.05%.

[0013] More preferably, the 0Cr27Al7Mo2NbY material is prepared according to the following steps: Step 1: Mix all raw materials according to the element ratio, add them to a vacuum induction melting furnace for vacuum induction melting, and control the vacuum level at 10. -2 kPa, melting temperature is 1560~1600℃, refining time is 30~60min; Among them, yttrium (Y) is added using an Al-Y master alloy; niobium (Nb) is added using an Fe-Nb master alloy; Step 2: Hot working of the steel ingots formed after melting, at 900~1000℃; The third step is to open the hot-processed steel ingots and hot-roll them into wire rods.

[0014] Compared with the prior art, the present invention has the following beneficial effects: First, this invention uses a specially formulated heating wire material, 0Cr27Al7Mo2NbY. This material is based on the original iron-based high-temperature alloy (0Cr27Al7Mo2) material, with the addition of niobium and yttrium rare earth elements. Through micro-alloying treatment, the material's high-temperature strength and oxidation resistance are further improved. Niobium refines the grains, inhibits excessive grain growth at high temperatures, and enhances the material's creep resistance; yttrium forms a stable oxide film, improving the heating wire's resistance to high-temperature oxidation during long-term operation at 1000℃. This solves the problems of traditional iron-based high-temperature alloy materials being prone to embrittlement at high temperatures, having rapid oxidation rates, and short service life. The specially formulated heating wire material of this invention also incorporates titanium, further improving the heating wire's corrosion resistance.

[0015] Secondly, the heat storage bricks of this invention have a concave-convex structure on both the top and bottom, forming a unified structure for the heat storage body, while leaving an expansion joint of about 1mm between each heat storage brick. At high heat storage temperatures, the heat storage body will not deform due to expansion.

[0016] Third, the spiral heating wire connecting plate of this invention is fixed to the end of the heat storage body with stainless steel bolts. At temperatures above 1200℃, the spiral heating wire will not creep, solving the problem of short circuit faults between heating wires and improving the safety performance and working efficiency of the equipment.

[0017] Fourth, this invention uses a lens structure to measure the temperature of the heating wire with infrared light. The heat storage brick is specially shaped to form holes in the heat storage body. A corundum thermocouple is used to measure the temperature inside the heat storage body, which can conveniently realize the temperature detection of the heating wire and the heat storage body.

[0018] Fifth, the thermal insulation layer around and at the top of the heat storage body in this invention utilizes a composite insulation structure consisting of an inner insulation layer, a phase change heat storage module, and an outer insulation layer. Heat exchange pipes are pre-embedded in the concrete foundation, further improving the insulation performance of the high-temperature electric heating heat storage equipment. In particular, by employing low-temperature phase change technology, the heat storage capacity per unit area of ​​the equipment wall can be increased, reducing heat loss and improving heat utilization. Through multi-layer insulation, the outer surface temperature of the top layer is reduced to below 35°C and remains relatively stable. The outer insulation body of this invention uses a high-purity silicate fiber insulation module, wherein Al2O3 ≥ 47%; Al2O3 + SiO2 ≥ 99%. A phase change composite insulation layer is used around the perimeter and top, and stainless steel coils are embedded in the bottom concrete foundation to absorb heat diffused from the bottom. These measures ensure that heat loss is within 1%. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the solid thermal energy storage device of the present invention.

[0020] Figure 2 This is a schematic diagram of the heating wire assembly in an embodiment of the solid thermal storage device of the present invention.

[0021] Figure 3 This is a schematic diagram of the insulation mechanism in an embodiment of the solid heat storage device of the present invention.

[0022] Figure 4 This is a schematic diagram of the phase change heat storage module in the insulation mechanism of an embodiment of the solid heat storage device of the present invention.

[0023] Figure 5 This is a schematic diagram of the end face structure of the heat storage body in an embodiment of the solid heat storage device of the present invention.

[0024] Figure 6 This is a three-dimensional structural diagram of the heat storage body in an embodiment of the solid heat storage device of the present invention.

[0025] Figure 7 This is a schematic diagram of the upper structure of the heat storage brick in an embodiment of the solid heat storage device of the present invention.

[0026] Figure 8This is a schematic diagram of the lower structure of the heat storage brick in an embodiment of the solid heat storage device of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. Heat storage body; 1-1. Heat storage brick; 1-1-1. Protrusion; 1-1-2. Groove; 1-2. Heating wire channel; 1-3. Fixing bolt; 1-4. Thermocouple socket; 2. Top wall; 2-1. Inner insulation layer of top wall; 2-2. Phase change heat storage module of top wall; 2-3. Outer insulation layer of top wall; 3. Side wall; 3-1. Inner insulation layer of side wall; 3-2. Phase change heat storage module of side wall; 3-3. Outer insulation layer of side wall; 4. Corundum thermocouple; 5. Heating wire assembly; 5-1. Connecting plate; 5-2. Spiral heating wire; 6. Infrared temperature sensor; 7. High-purity quartz glass lens; 8. Concrete foundation; 9. Heat exchanger; 10. Fan; 11. Heat exchange tube of foundation layer; 12. Heat exchange tube of insulation layer; 13. Phase change heat storage material; 14. Phase change heat storage module shell. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments.

[0029] An embodiment of the solid heat storage device of the present invention includes a heat storage body 1 and a heat storage body 1 insulation mechanism.

[0030] like Figure 5 and Figure 6 The heat storage body 1 includes heat storage bricks 1-1, with heating wire channels 1-2 between adjacent heat storage bricks 1-1. The heat storage body 1 also includes... Figure 2 The heating wire assembly 5 shown includes a connecting plate 5-1 and a spiral heating wire 5-2 connected to the connecting plate 5-1. The spiral heating wire 5-2 is arranged in the heating wire channel 1-2. The connecting plate 5-1 is fixed to the heat storage brick at the end of the heat storage body by fixing bolts 1-3.

[0031] The top and bottom surfaces of the heat storage brick 1-1 adopt a convex-concave structure with interlocking joints. In the horizontal direction, an expansion joint of about 1 mm is left between adjacent heat storage bricks 1-1.

[0032] Specifically, in combination Figure 6 , Figure 7 and Figure 8 The upper side of a lower heat storage brick 1-1 has several protrusions 1-1-1, and the lower side of a corresponding upper heat storage brick 1-1 has grooves 1-1-2 that correspond one-to-one with the protrusions 1-1-1. The protrusions 1-1-1 are inserted into the corresponding grooves 1-1-2 to combine the upper and lower heat storage bricks into a whole.

[0033] like Figure 1The insulation mechanism includes side walls 3, a top wall 2, and a concrete foundation 8. Specifically, the side walls 3 include four side walls located on the left, right, front, and rear sides of the heat storage body 1. These four side walls are connected end-to-end and enclose a cuboid heat storage space with the top wall 2 and the concrete foundation 8. One side wall has a circulating air inlet and outlet, and the internal space of the insulation mechanism is connected to the heat exchanger 9 and the fan 10 through the circulating air inlet and outlet. The above structure is a conventional structure for solid heat storage equipment.

[0034] like Figure 3 The side wall 3 includes an outer insulation layer 3-3, an inner insulation layer 3-1, and a phase change heat storage module 3-2 located between the outer insulation layer 3-3 and the inner insulation layer 3-1. The top wall 2 includes an outer insulation layer 2-3, an inner insulation layer 2-1, and a phase change heat storage module 2-2 located between the outer insulation layer 2-3 and the inner insulation layer 2-1.

[0035] like Figure 4 Both the sidewall phase change heat storage module 3-2 and the top wall phase change heat storage module 2-2 are rectangular flat plates. They each include a rectangular flat plate (flat cuboid) phase change heat storage module shell 14. The phase change heat storage module shell 14 contains a serpentine insulated heat exchange pipe 12 and is filled with phase change heat storage material 13. The concrete foundation 8 has a pre-embedded foundation layer heat exchange pipe 11.

[0036] The two ends of the heat exchange tube 12 in the insulation layer serve as the inlet and outlet of the tube-side medium, respectively, and extend out from the phase change heat storage module shell 14. The two ends of the heat exchange tube 11 in the foundation layer serve as the inlet and outlet of the tube-side medium, respectively, and extend out from the concrete foundation 8.

[0037] The inlet end of each heat exchange tube (including the insulation layer heat exchange tube 12 and the foundation layer heat exchange tube 11) is connected to an inlet manifold, and the outlet end of the medium is connected to an outlet manifold. When heat energy needs to be extracted from the phase change heat storage module and the concrete foundation 8, a water pump is used to pump circulating medium (such as low-temperature water) into the inlet manifold. After absorbing heat in the phase change heat storage module and the concrete foundation, the circulating medium is discharged through the outlet manifold.

[0038] Specifically, the external insulation layer 3-3 of the side wall and the external insulation layer 2-3 of the top wall are both fiber felt with a thickness of approximately 90mm. The internal insulation layer 3-1 of the side wall and the internal insulation layer 2-1 of the top wall are both aluminum silicate fiber modules with a thickness of approximately 300mm. The aluminum silicate fiber modules are high-purity aluminum silicate fiber insulation modules, requiring Al2O3 ≥ 47% (mass percentage); Al2O3 + SiO2 ≥ 99% (mass percentage).

[0039] The phase change heat storage module (the phase change heat storage module is a general term for the side wall phase change heat storage module 3-2 and the top wall phase change heat storage module 2-2) is approximately 100mm thick. The phase change heat storage module housing 14 is made of stainless steel.

[0040] The preparation method of the phase change heat storage module is as follows: the phase change heat storage module shell 14 is welded from stainless steel plates into a box structure, the heat exchange tube 12 in the form of stainless steel tube is installed inside, the outer cavity of the heat exchange tube 12 is filled with phase change heat storage material 13, the two ends of the heat exchange tube 12 pass through the phase change heat storage module shell 14 respectively, and the passing parts are welded and sealed.

[0041] The phase change thermal storage material 13 is a binary eutectic salt: it is composed of magnesium sulfate heptahydrate, sodium dihydrogen phosphate dihydrate, nucleating agent and thickener, and can stably carry out phase change thermal storage at a temperature of about 50°C.

[0042] Example of the composition of phase change thermal energy storage material: MgSO4•7H2O accounts for 70% by mass, NaH2PO4•2H2O accounts for 28% by mass, borax (Na2B4O7·10H2O) nucleating agent accounts for 1.5% by mass, and sodium carboxymethyl cellulose (CMC) thickener accounts for 0.5% by mass.

[0043] Example of physical properties of phase change thermal storage material: phase change temperature 49~51℃, latent heat of phase change 156KJ / Kg, solid density 1640Kg / m3, liquid density 1460Kg / m3, solid thermal conductivity 0.52W / (mK), liquid thermal conductivity 0.58W / (mK), solid specific heat capacity 1.6 KJ / Kg, liquid specific heat capacity 2 KJ / Kg, operating temperature 30~55℃.

[0044] Combination Figure 1 and Figure 5 The heat storage brick 1-1 has a thermocouple socket 1-4. This embodiment also includes a corundum thermocouple 4 that passes through the side wall 3 into the thermocouple socket 1-4 and is used to detect the temperature of the heat storage body.

[0045] like Figure 1 This embodiment also includes an infrared temperature sensor 6 for detecting the temperature of the spiral heating wire. The infrared temperature sensor 6 penetrates into the internal space of the insulation mechanism from the side wall 3, and a high-purity quartz glass lens 7 is installed at its inner end. The high-purity quartz glass lens 7 is at the same height as the spiral heating wire being detected.

[0046] In this embodiment of the invention, the spiral heating wire material 0Cr27Al7Mo2NbY is made from the following raw materials in the following weight percentages: chromium (Cr): 29.0%, aluminum (Al): 9.0%, molybdenum (Mo): 2.0%, carbon (C): 0.08%, silicon (Si): 1.0%, manganese (Mn): 1.0%, phosphorus (P): 0.03%, sulfur (S): 0.030%, yttrium (Y): 0.10%, niobium (Nb): 0.30%, titanium (Ti): 0.80%, with the balance being iron and unavoidable impurity elements; the weight percentage of unavoidable impurity elements is ≤0.05%.

[0047] The following examples illustrate the preparation steps of the spiral heating wire material 0Cr27Al7Mo2NbY and the heating wire of the present invention.

[0048] A. After preparing and mixing all raw materials, add them to a vacuum induction melting furnace for vacuum induction melting, controlling the vacuum level at 10. -2 The working pressure is kPa, the melting temperature is 1580℃, and the refining time is 30 min. Yttrium (Y) is added using an Al-Y master alloy (Al-10%Y). Niobium (Nb) is added using an Fe-Nb master alloy (Fe-10%Nb).

[0049] B. Perform composition analysis on the steel ingots formed after smelting. If the composition is not up to standard, prepare the raw materials again. If the composition is up to standard, perform hot working on the steel ingots at 950°C, avoiding the low-temperature brittleness zone.

[0050] C. The steel ingots after hot processing in step B are shaped into billets and hot rolled into wire rods.

[0051] D. The wire rod formed after hot rolling is annealed at a temperature of 900℃ for 2 hours.

[0052] E. After annealing, the wire rod is heated to 450℃ and then hot-drawn to form a heating wire.

[0053] F. Finally, inspect the finished product. If the inspection fails, prepare new raw materials and start production again. If the inspection passes, package and put it into storage.

Claims

1. A solid heat storage device with a high heat storage temperature, comprising a heat storage body (1) and a heat insulation mechanism, wherein the heat storage body (1) comprises a heat storage brick (1-1) and a heating wire assembly (5), the heating wire assembly (5) comprises a connecting plate (5-1) and a spiral heating wire (5-2) connected to the connecting plate (5-1), and the heat insulation mechanism comprises a side wall (3), a top wall (2) and a concrete foundation (8), characterized in that: The side wall (3) and the top wall (2) respectively include an outer insulation layer, an inner insulation layer and a phase change heat storage module located between the outer insulation layer and the inner insulation layer; the phase change heat storage module includes a phase change heat storage module shell (14), and the phase change heat storage module shell (14) is equipped with an insulation layer heat exchange tube (12) and filled with phase change heat storage material (13); the inner insulation layer is an aluminum silicate fiber module; the concrete foundation (8) has a foundation layer heat exchange tube (11) pre-embedded inside.

2. The solid thermal storage device with high thermal storage temperature as described in claim 1, characterized in that: The heat storage brick (1-1) has a thermocouple socket (1-4); the solid heat storage device includes a corundum thermocouple (4) that passes through the thermocouple socket (1-4) from the side wall (3) and is used to detect the temperature of the heat storage body.

3. The solid thermal storage device with high thermal storage temperature as described in claim 1, characterized in that: The solid heat storage device includes an infrared temperature sensor (6) for detecting the temperature of the spiral heating wire; the infrared temperature sensor (6) extends from the side wall (3) into the internal space of the heat preservation mechanism, and a high-purity quartz glass lens (7) is installed at its inner end.

4. The solid thermal storage device with high thermal storage temperature as described in claim 1, characterized in that: The two ends of the heat exchange tube (12) of the insulation layer are respectively the tube-side medium inlet and outlet ends, which pass through the phase change heat storage module shell (14) and are connected to the manifold; the two ends of the heat exchange tube (11) of the foundation layer are respectively the tube-side medium inlet and outlet ends, which pass through the concrete foundation (8) and are connected to the manifold.

5. The solid thermal storage device with high thermal storage temperature as described in claim 1, characterized in that... The aluminum silicate fiber module uses high-purity aluminum silicate fiber insulation module, wherein Al2O3 ≥ 47%; Al2O3 + SiO2 ≥ 99%.

6. The solid thermal storage device with high thermal storage temperature as described in claim 1, characterized in that: The heat storage brick (1-1) has a convex-concave structure on its upper and lower surfaces that fit together; in the horizontal direction, an expansion joint is left between adjacent heat storage bricks (1-1).

7. The solid thermal storage device with high thermal storage temperature as described in claim 1, characterized in that: The connecting plate (5-1) is fixed to the heat storage brick at the end of the heat storage body by fixing bolts (1-3).

8. The solid thermal storage device with high thermal storage temperature as described in claim 1, characterized in that: The phase change thermal storage material (13) is composed of magnesium sulfate heptahydrate, sodium dihydrogen phosphate dihydrate, nucleating agent and thickener.

9. The solid thermal storage device with high thermal storage temperature as described in any one of claims 1-8, characterized in that: The spiral heating wire (5-2) is made of 0Cr27Al7Mo2NbY material; the 0Cr27Al7Mo2NbY material is made from the following raw materials in the following weight percentages: chromium: 28.0~30.0%, aluminum: 8.0%~10.0%, molybdenum: 1.5%~2.5%, carbon ≤ 0.08%, silicon ≤ 1.0%, manganese ≤ 1.0%, phosphorus ≤ 0.03%, sulfur ≤ 0.030%, yttrium: 0.07%~0.13%, niobium: 0.20%~0.40%, titanium: 0.70%~0.90%, with the balance being iron and unavoidable impurity elements; the weight percentage of unavoidable impurity elements is ≤0.05%.

10. The solid thermal storage device with high thermal storage temperature as described in claim 9, characterized in that: The 0Cr27Al7Mo2NbY material was prepared according to the following steps: Step 1: Mix all raw materials according to the element ratio, add them to a vacuum induction melting furnace for vacuum induction melting, and control the vacuum degree at 10. -2 kPa, melting temperature is 1560~1600℃, refining time is 30~60min; Among them, yttrium (Y) is added using an Al-Y master alloy; niobium (Nb) is added using an Fe-Nb master alloy; Step 2: Hot working of the steel ingots formed after melting, at 900~1000℃; The third step is to open the hot-processed steel ingots and hot-roll them into wire rods.

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