Solar high-temperature heat utilization system with multiple layers of heat storage balls

Abstract

The invention discloses a solar high-temperature heat utilization system with multilayer heat storage balls, which comprises a circulating fan, a heat absorption tower, a heat absorber and a heat storage bin, the heat storage bin is arranged into multiple layers, each layer of material storage layer is provided with a plurality of heat storage balls for heat energy storage, and heat absorption and heat carrying media are stored in the heat storage balls. A gap is reserved between every two adjacent heat storage balls. The problems that a fused salt medium system is complex, and the freezing and blocking risk is high can be effectively solved. Meanwhile, efficient fluid channels can be formed among the spherical heat storage bodies which are arranged in multiple layers; through special design, the whole process of heat storage and heat release can be completed by adopting a set of circulating fan system, and the temperature distribution that the upper part of the heat storage ball is high and the lower part of the heat storage ball is low is realized. The factors are beneficial to heat exchange between the circulating air and the heat storage ball, and the heat / electricity utilization process of the follow-up process is facilitated. The system can be used as a reasonable choice for solar high-temperature heat utilization.

Description

Technical Field

[0001] The invention relates to the technical field of solar thermal utilization, and in particular to a solar high-temperature thermal utilization system with multi-layer heat storage balls. Background Art

[0002] Solar high temperature thermal power generation technology is an important direction for the large-scale utilization of solar energy, and has far-reaching significance for mankind to solve the fossil energy crisis, air pollution and other problems. According to different focusing methods, solar high temperature thermal power generation can be divided into three types: dish type, trough type and tower type; the working fluids used are water (steam), molten salt, air, thermal oil, liquid metal, other organic matter, etc. Tower focusing has attracted the attention of many countries in the world due to its advantages such as large capacity and high parameters.

[0003] Tower thermal power generation technology is already in the early stages of commercial operation abroad, with large-scale commercial projects that have been built or are under construction on almost every continent. This technology route has demonstrated strong market and vitality. In particular, solar thermal power generation technology with heat storage has broad application prospects due to its longer power generation time and more stable power output. my country's tower thermal power generation industry is currently still in the demonstration operation stage. After the solar thermal power generation price is clarified and the demonstration project is successfully implemented, my country's solar thermal power generation industry will usher in a period of rapid development.

[0004] Among the tower thermal power generation technology routes, the most commonly used technologies are water working fluid and molten salt working fluid. Water working fluid technology has the advantages of cheap working fluid, high safety, and low initial investment cost, but this technology also has problems such as high working pressure and difficulty in water and steam heat storage. The solar thermal power generation system using molten salt working fluid has the advantages of high working temperature, low working pressure, easy large-scale heat storage, stable power output, and high grid acceptance, but the molten salt system also has risks such as complex system and easy freezing of molten salt, which to a certain extent restricts the large-scale development of this technology. Summary of the invention

[0005] In order to solve the above technical problems, the present invention designs a solar high-temperature heat utilization system with multi-layer heat storage balls.

[0006] The present invention adopts the following technical solution: A solar high temperature heat utilization system with multi-layer heat storage balls, comprising a circulating fan (or air compressor), a heat absorption tower, a heat absorber and a heat storage bin, wherein the heat absorber is mounted on the heat absorption tower, and the two ends of the heat absorber are connected to the upper and lower ends of the heat storage bin through pipelines 1 and 2 respectively, the upper end of the heat storage bin is connected to the heat removal / electricity user end through pipeline 3, and the lower end of the heat storage bin is connected to the self-heating / electricity user end through pipeline 4, and a circulating fan is mounted on pipeline 4, wherein the heat storage bin is arranged in multiple layers, and each layer of the storage material is connected to the heat removal / electricity user end through pipeline 3. The airflow is flowing, and each layer is arranged with multiple heat storage balls for thermal energy storage. The heat storage balls store heat absorption and heat-carrying media. There are gaps between adjacent heat storage balls. The lower end of the heat storage bin is connected to the self-heating / electricity user end through pipeline five. Switching valve three is installed on pipeline one, switching valve one is installed on pipeline two, switching valve four is installed on pipeline three, switching valve five is installed on pipeline five, switching valve two is installed between the lower end of the heat storage bin and pipelines two and four, and switching valve six is ​​installed at the self-heating / electricity user end. The absorber on the heat absorption tower absorbs the sunlight reflected by the heliostat and transfers it to the heat storage ball through circulating wind. There are certain gaps between adjacent heat storage balls. During the heat storage process, the circulating wind flows through the gaps to transfer the heat to the heat storage balls. In the heat release process, the circulating wind passing through the gaps takes the heat out of the heat storage balls and then transports it to the heat / electricity users for external heating or power generation.

[0007] For tower thermal power generation technology, in order to obtain stable power output and a long heat storage time, a double tank system with molten salt as the heat absorption and heat carrier medium is currently commonly used. The molten salt in the low-temperature molten salt tank first passes through the upper tower pipeline, then flows through the complex absorber circuit, absorbs the heat converted by solar energy and becomes high-temperature molten salt, then returns to the ground through the lower tower pipeline and is stored in the high-temperature molten salt tank; when power generation is required, the high-temperature molten salt flows out of the high-temperature tank, and when passing through the steam generation system, it generates steam with the required parameters for power generation, and the cooled molten salt returns to the cold salt tank. The molten salt thermal power generation system has complex pipelines, and because the freezing point of molten salt is usually high (the freezing point of commonly used solar salt exceeds 200°C), the risk of freezing and blocking is high when the molten salt system is in operation. In particular, when freezing and blocking occurs on the solar thermal absorber, it may cause risks such as overheating, overheating, and even damage to the absorber, which will seriously threaten the safe operation of the solar thermal power generation system.

[0008] The present invention provides a solar high-temperature heat utilization system with a multi-layer heat storage ball structure. The multi-layer heat storage balls are neatly arranged in the heat storage bin. Due to the regular shape of the balls, a flow gap with a specific rule is formed between adjacent heat storage balls. The heat storage ball layers from top to bottom can use the same or different heat storage media according to the different heat storage temperatures. It can be an energy storage medium that utilizes sensible heat, or a composite phase change material that mainly utilizes latent heat. The heat carrier medium used in the system is usually air, and carbon dioxide, nitrogen, etc. can also be used as the heat carrier medium according to the different materials of the heat storage balls. Driven by a circulating fan (or compressor), the heat carrier medium absorbs the heat converted by solar energy in the solar thermal absorber, and transfers the heat to the heat storage balls when passing through the gaps between the multi-layer heat storage balls. When needed, the circulating wind releases the heat from the heat storage balls for external heating or power generation.

[0009] Preferably, the heat storage balls of different storage layers can be made of different types of materials according to different working temperatures.

[0010] Preferably, the heat storage ball is made of a heat storage material that is mainly sensible heat or a composite phase change material that is mainly latent heat. This system can eliminate the freezing risk of a thermal power generation system using molten salt as a working fluid and improve the safety of the system. Preferably, the heat absorbing and heat-carrying medium is air, carbon dioxide or nitrogen. Air, carbon dioxide, nitrogen or the like is used as the heat absorbing and heat-carrying medium to convert the absorbed solar energy into heat energy and store it in the multi-layer heat storage balls in the heat storage bin.

[0011] Preferably, the heat storage bin comprises three layers, an upper storage layer, a middle storage layer and a lower storage layer.

[0012] Preferably, the heat storage balls are arranged neatly in the storage layer.

[0013] Preferably, the switching valve one, switching valve two, switching valve three, switching valve four, switching valve five and switching valve six are electrically controlled valves.

[0014] The beneficial effects of the present invention are as follows: (1) Circulating wind is used to absorb and carry away the heat generated by solar energy, and the heat is stored in a heat storage bin with multiple layers of heat storage balls, thereby avoiding a complex system using molten salt as a heat absorption / heat carrier medium and improving the safety of the system; (2) The heat storage balls can use sensible heat storage or high-temperature composite phase change materials; if composite phase change materials are used, the materials usually have a higher heat capacity, thereby reducing the amount and volume of the heat storage materials; (3) When the spherical heat storage bodies are arranged regularly, curved, variable, and regular fluid channels are formed between the heat storage balls, so that the airflow can fully contact the heat storage balls, thereby enhancing the heat exchange effect between the heat carrier fluid and the heat storage balls; (4) Through the optimized design of the circulating wind system, a set of fan systems can be used to realize heat storage and heat release of the heat storage system: when storing heat, hot air enters from the top of the heat storage bin and is discharged from the bottom after releasing heat; when releasing heat, cold air enters from the bottom of the heat storage bin, absorbs heat, and is discharged from the top of the heat storage bin after heating, and is transported to heat / electricity users. This design can simplify the system and save initial investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the principle of the present invention in the heat storage mode; Figure 2 It is a schematic diagram of the principle of the present invention in the heat release mode; In the figure: 1. circulating fan, 2. heat absorption tower, 3. heat absorber, 4. heat storage bin, 5. switching valve one, 6. switching valve two, 7. switching valve three, 8. switching valve four, 9. switching valve five, 10. switching valve six, 41. upper heat storage ball, 42. middle heat storage ball, 43. lower heat storage ball. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings: Example: Figure 1 and Figure 2As shown, a solar high temperature heat utilization system with multi-layer heat storage balls includes a circulating fan 1, a heat absorption tower 2, a heat absorber 3, a heat storage bin 4, a switching valve 1 5, a switching valve 2 6, a switching valve 3 7, a switching valve 4 8, a switching valve 5 9, and a switching valve 6 10. The heat absorber is installed on the heat absorption tower, and the two ends of the heat absorber are connected to the upper and lower ends of the heat storage bin through pipeline 1 and pipeline 2 respectively. The upper end of the heat storage bin is connected to the heat removal / electricity user end through pipeline 3, and the lower end of the heat storage bin is connected to the self-heating / electricity user end through pipeline 4. A circulating fan is installed on pipeline 4, and the lower end of the heat storage bin is connected to the self-heating / electricity user end through pipeline 5. A switching valve 3 is installed on pipeline 1, a switching valve 1 is installed on pipeline 2, a switching valve 4 is installed on pipeline 3, and a switching valve 5 is installed on pipeline 5. A switching valve 2 is installed between the lower end of the heat storage bin and pipelines 2 and 4, and a switching valve 6 is provided at the self-heating / electricity user end. The heat storage bin 4 is designed to be one or more layers according to actual needs. In this example, it is designed to be three layers. Airflow circulates between each storage layer. The three layers are respectively arranged with upper heat storage balls 41, middle heat storage balls 42, and lower heat storage balls 43. Each heat storage ball stores heat absorbing and heat carrying media, and gaps are reserved between adjacent heat storage balls. For a complete solar thermal power generation system, it also includes heliostats, steam generation systems, power generation systems, etc., but the above systems are not strongly related to the basic principles of the present invention, so they are not elaborated here.

[0017] like Figure 1 As shown, when the system works in the heat storage mode, the switching valve 1 5, the switching valve 3 7, and the switching valve 5 9 are opened, and the switching valve 2 6, the switching valve 4 8, and the switching valve 6 10 are closed (Note: Figure 1 The valves in the closed state are marked in black). The specific work flow is described as follows: The circulating air with a relatively low temperature (usually air, carbon dioxide, nitrogen, etc.) is driven by the circulating fan 1 and enters the heat absorber 3 at the top of the heat absorption tower 2 through the switching valve 1 5, absorbs the heat energy generated by the solar energy in the heat absorber 3, and the temperature rises to the set temperature, flows through the switching valve 3 7 and enters the upper part of the heat storage bin 4, flows through the upper heat storage ball 41, the middle heat storage ball 42, and the lower heat storage ball 43 in turn, and is discharged from the lower part of the heat storage bin 4 after the temperature gradually decreases, and then returns to the inlet of the circulating fan 1 through the switching valve 5 9, completing a heat storage cycle of the medium.

[0018] When the heat storage process is completed, the heat storage bin 4 has a distribution with the upper layer having the highest temperature, the middle layer having the second highest temperature, and the lower layer having the lowest temperature. This distribution method can effectively avoid heat convection, reduce the entropy increase in the heat storage ball, and is beneficial to the subsequent heat / electricity process.

[0019] Figure 2 Schematic diagram of the principle of the present invention in the heat release mode. In this mode, the switching valve 2 6, the switching valve 4 8, and the switching valve 6 10 are opened, and the switching valve 1 5, the switching valve 3 7, and the switching valve 5 9 are closed (Note: Figure 2The valves in the closed state are marked in black). The specific working process is described as follows: the switching valve 6 10 is opened, and the circulating air with a lower temperature (usually air, carbon dioxide, nitrogen, etc.) enters the lower part of the heat storage bin 4 through the switching valve 2 6 under the drive of the circulating fan 1, and flows through the lower heat storage ball 43, the middle heat storage ball 42, and the upper heat storage ball 41 in sequence. After the temperature gradually rises, it flows out from the upper part of the heat storage bin 4, and then flows to the heat / electricity user through the switching valve 4 8, completing the heat release process on the user side. The circulating air returned from the heat / electricity user passes through the switching valve 6 10 and enters the inlet of the circulating fan 1 again, completing a heat release cycle of the medium.

[0020] Whether it is a heat storage or heat release process, when the circulating air flows through the gaps between the heat storage balls, since the flow channels formed between the heat storage balls are curved, changeable and regular, it can increase the turbulence of the fluid, reduce the thickness of the boundary layer, and enhance the heat exchange effect between the two.

[0021] The present invention can effectively avoid the problems of complex molten salt medium system and high risk of freezing and blocking. At the same time, efficient fluid channels can be formed between the multi-layer spherical heat storage bodies; through special design, a set of circulating fan system can be used to complete the whole process of heat storage and heat release, and achieve a high temperature distribution at the top and low temperature at the bottom of the heat storage ball. These factors are conducive to the heat exchange between the circulating wind and the heat storage ball, and the heat / electricity utilization process of the subsequent process is utilized. The system can be used as a reasonable choice for the utilization of high-temperature solar heat.

[0022] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A solar high temperature heat utilization system with multi-layer heat storage balls, comprising a circulating fan, a heat absorption tower, a heat absorber and a heat storage bin, wherein the heat absorber is installed on the heat absorption tower, and the two ends of the heat absorber are connected to the upper and lower ends of the heat storage bin through pipeline 1 and pipeline 2 respectively, the upper end of the heat storage bin is connected to the heat removal / electricity user end through pipeline 3, and the lower end of the heat storage bin is connected to the self-heating / electricity user end through pipeline 4, and a circulating fan is installed on pipeline 4, characterized in that: The heat storage bin is arranged in multiple layers, and air flows between each material storage layer. Each layer is arranged with multiple heat storage balls for storing thermal energy. The heat storage balls store heat absorbing and heat carrying media. Gaps are reserved between adjacent heat storage balls. The lower end of the heat storage bin is connected to the self-heating / electricity user end through pipeline five. A switching valve three is installed on pipeline one, a switching valve one is installed on pipeline two, a switching valve four is installed on pipeline three, and a switching valve five is installed on pipeline five. A switching valve two is installed between the lower end of the heat storage bin and pipelines two and four, and a switching valve six is ​​arranged at the self-heating / electricity user end.

2. A solar high temperature heat utilization system with multi-layer heat storage balls according to claim 1, characterized in that: The heat storage balls of different storage layers can be made of different types of materials according to different working temperatures.

3. A solar high temperature heat utilization system with multi-layer heat storage balls according to claim 2, characterized in that: The heat storage ball is made of a heat storage material mainly based on sensible heat or a composite phase change material mainly based on latent heat.

4. The solar high temperature heat utilization system with multi-layer heat storage balls according to claim 1 is characterized in that: The heat absorbing and heat carrying medium is air, carbon dioxide or nitrogen.

5. The solar high temperature heat utilization system with multi-layer heat storage balls according to claim 1 is characterized in that: The heat storage bin comprises three layers, an upper storage layer, a middle storage layer and a lower storage layer.

6. The solar high temperature heat utilization system with multi-layer heat storage balls according to claim 1 is characterized in that: The heat storage balls are arranged neatly in the material storage layer.

7. The solar high temperature heat utilization system with multi-layer heat storage balls according to claim 1 is characterized in that: The switching valve 1, switching valve 2, switching valve 3, switching valve 4, switching valve 5 and switching valve 6 are electrically controlled valves.

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