SCO2 fluidized bed heat exchanger, system and method suitable for thermochemical particles

Abstract

The invention relates to the technical field of fluidized beds, in particular to an sCO2 fluidized bed heat exchanger, system and method suitable for thermochemical particles, a mixing bin, a heating bin and a cooling bin which are sequentially communicated are formed in the heat exchanger, the mixing bin is communicated with a mixing bin air chamber, the heating bin is communicated with a heating bin air chamber, and the cooling bin is communicated with a cooling bin air chamber; external air is conveyed to the air chamber of the mixing bin and the air chamber of the heating bin, and external flue gas with the oxygen content and the temperature lower than set values is introduced into the air chamber of the cooling bin. The sCO2 is heated by the heating bin to generate power outwards; the thermochemical particles subjected to sCO2 heat exchange still have high temperature, and are transported and stored after being further cooled by the cooling bin, so that the problem that the high-temperature thermochemical particles are difficult to transport is avoided. The chambers in the fluidized bed heat exchanger are partitioned, air fluidization is adopted in the mixing chamber and the heating chamber, the thermal chemical particles can be promoted to react with oxygen to release heat, low-temperature flue gas with low oxygen content is adopted in the cooling chamber for cooling, and the cooling speed of the thermal chemical particles is further increased.

Description

Technical Field

[0001] The present invention relates to the technical field of fluidized beds, and specifically to an sCO2 fluidized bed heat exchanger, system and method applicable to thermochemical particles. Background Art

[0002] Supercritical carbon dioxide (abbreviated as sCO2) power generation system belongs to a kind of power system, which uses carbon dioxide in a supercritical state as the working medium to convert the heat of a heat source into mechanical energy. Due to the special advantages of supercritical carbon dioxide, the power generation system using this working medium has advantages such as high efficiency and small volume, and is a development direction for future comprehensive energy utilization. China has superior natural resource endowments and is one of the countries rich in solar energy resources. Using solar energy as the energy supply for the supercritical carbon dioxide system and developing corresponding systems and equipment have profound strategic significance for ensuring China's energy security.

[0003] Patent CN109682096A proposes a solar energy thermal energy storage system based on solid particles, which uses solid particles to absorb the heat of solar beams and stores it in a high-temperature particle storage bin, and then exchanges heat with the working medium through a fluidized bed heat exchange device to achieve efficient thermal energy storage and utilization of solar energy.

[0004] Patent CN215831879U proposes a multi-stage fluidized bed solid particle steam generator, which divides the fluidized bed heat exchanger into multiple bins, and provides high-quality steam externally through the settings of an empty bin, a superheat bin, an evaporation bin and a heating bin.

[0005] The above patents mainly use inert solid particles as the heat storage medium, and use water to exchange heat with the solid particles during the energy release stage. The solid particles do not react during the whole process. Currently, there is no design and research on the sCO2 fluidized bed heat exchanger for related thermochemical particles. In this system, thermochemical particles will react with oxygen in the fluidizing air in the fluidized bed heat exchanger, and the heat of the material and chemical heat will be provided to sCO2 during the heat exchange process. The heated sCO2 is sent to the power generation system for power generation.

[0006] The so-called thermochemical particles are metal oxide particles that can reversibly undergo redox reactions within a certain temperature range. Compared with inert particles, they have advantages such as large specific heat capacity, strong reaction stability, and reaction reversibility. Thermochemical particles have both sensible heat and latent heat, so they have a large specific volume, which is conducive to maintaining a constant temperature. They absorb heat and produce oxygen during the reaction at high temperatures, and the reaction proceeds reversely at low temperatures, releasing heat when reacting with oxygen.

[0007] It can be seen that there is still room for improvement in the current scheme of using inert particles for heat exchange, and it should be optimized to improve the heat exchange effect. Therefore, a more reasonable technical solution needs to be proposed to solve the technical problems existing in the prior art. Summary of the Invention

[0008] To overcome at least one of the above-mentioned defects, the present invention proposes an sCO2 fluidized bed heat exchanger, system and method applicable to thermochemical particles, which complete the efficient heat exchange between the thermochemical particles and sCO2 by using the thermochemical particles as the heat storage medium in the solar energy heat storage system.

[0009] To achieve the above object, the fluidized bed heat exchanger disclosed by the present invention may adopt the following technical solutions:

[0010] The sCO2 fluidized bed heat exchanger applicable to thermochemical particles has a mixing chamber, a heating chamber and a cooling chamber formed therein and connected in sequence. The mixing chamber is connected to a mixing chamber air chamber, the heating chamber is connected to a heating chamber air chamber, and the cooling chamber is connected to a cooling chamber air chamber; external air is conveyed to the mixing chamber air chamber and the heating chamber air chamber, and external flue gas with an oxygen content and temperature lower than the set value is introduced into the cooling chamber air chamber.

[0011] For the above-mentioned heat exchanger, by gradually pushing the high-temperature thermochemical particles forward, the sCO2 is heated in the heating chamber, and the heated sCO2 can be conveyed and applied to the power generation system; while the high-temperature thermochemical particles can be cooled in the cooling chamber, and after the temperature is reduced to the set temperature, they are conveyed backward and recycled.

[0012] Further, the structure inside the heat exchanger can adopt various forms, and its structure is not uniquely limited. Here, one feasible option is optimized and proposed: a front partition wall and a rear partition wall are arranged inside the heat exchanger to isolate the inner cavity of the heat exchanger to form a mixing chamber, a heating chamber and a cooling chamber. When adopting the above solution, a mixing chamber is formed between the front partition wall and the inner wall surface of the heat exchanger, a heating chamber is formed between the front partition wall and the rear partition wall, and a cooling chamber is formed between the rear partition wall and the inner wall surface of the heat exchanger.

[0013] Still further, when heat exchange is carried out, heat exchange can be carried out simultaneously through multiple chambers: the numbers of the mixing chamber, the heating chamber and the cooling chamber are all greater than one. When adopting the above solution, the arrangement of the mixing chamber, the heating chamber and the cooling chamber is not uniquely limited, and they can be arranged in multiple lines side by side, or arranged in other more ways.

[0014] Further, when introducing fluidizing air into the heat exchanger, multiple schemes can be adopted. For example, the mixing bin and the heating bin can be fluidized with external air, while the cooling bin is fluidized with low-temperature and low-oxygen flue gas. The implementation structure is not uniquely defined. Here, an optimization is carried out and one feasible option is proposed: The cooling bin is connected to the waste heat recovery device. The external air is heated by the waste heat recovery device and then transported into the mixing bin air chamber and the heating bin air chamber. Part of the flue gas discharged from the waste heat recovery device is introduced into the cooling bin air chamber. When adopting the above scheme, the high-temperature flue gas discharged from the cooling bin becomes low-temperature and low-oxygen flue gas after passing through the waste heat recovery device, which can be sent to the cooling bin as fluidizing gas, improving the energy utilization efficiency of the system.

[0015] Further, in some schemes, to enhance the heating effect of sCO2, the structure of the heating bin can be optimized. The structure is not uniquely defined. Here, an optimization is carried out and one feasible option is proposed: A heat-receiving structure is arranged in the heating bin, which is used to receive sCO2 and heat it. After heating, the sCO2 leaves the heat-receiving structure. When adopting the above scheme, the temperature of the sCO2 rises in the heater and is used for power generation and external transmission after rising.

[0016] Further, to improve the cooling effect on high-temperature thermochemical particles, an optimization is carried out here and one feasible option is proposed: A cooling structure for cooling thermochemical particles is arranged in the cooling bin. A cooling medium inlet and an outlet are arranged on the cooling structure. When the cooling medium enters the cooling structure, it exchanges heat with the thermochemical particles for cooling, and the cooled cooling medium leaves the cooling structure.

[0017] Furthermore, the cooling medium includes water or oil.

[0018] The above content discloses the structure of the heat exchanger. The present invention also discloses a heat exchange system, which will be described below.

[0019] An sCO2 fluidized bed heat exchange system applicable to thermochemical particles includes a low-temperature thermochemical particle storage tank, a thermochemical particle reduction device, a collector, a high-temperature thermochemical particle storage tank, and a fluidized bed heat exchanger. The sCO2 in a low-temperature state enters the fluidized bed heat exchanger and is heated to obtain high-temperature sCO2.

[0020] In the above heat exchange system, the thermochemical particles form a flowing cycle and can switch during the endothermic and exothermic processes, thereby realizing the heating treatment of sCO2.

[0021] The present invention also discloses a heating method for sCO2, which will be described below.

[0022] An sCO2 fluidized bed heat exchange method applicable to thermochemical particles adopts the heat exchange system described above, including

[0023] Heat storage stage: The oxidized low-temperature thermochemical particles enter the thermochemical particle reduction device for reduction, and then enter the collector to be heated to a set temperature to become high-temperature thermochemical particles.

[0024] Energy release stage: The high-temperature thermochemical particles enter the fluidized bed heat exchanger to heat sCO2. The heat exchange process includes the physical sensible heat of the high-temperature thermochemical particles and the heat generated by the reaction of the high-temperature thermochemical particles with the fluidizing air. The thermochemical particles after heat release are then transported backward to resume heat storage.

[0025] Furthermore, the flow circulation paths of the high-temperature thermochemical particles and sCO2 in the heat exchanger are different. Optimization is carried out here and one feasible option is proposed: In the energy release stage, the high-temperature thermochemical particles enter from the mixing bin, are mixed evenly under the action of the fluidizing air in the mixing bin, and then enter the heating bin; the high-temperature thermochemical particles in the heating bin heat sCO2 through physical sensible heat and chemical heat; the high-temperature thermochemical particles after heat release enter the cooling bin for cooling until the temperature is reduced to the set temperature and then transported backward. When the above scheme is adopted, sCO2 is connected to the external heat exchange structure and is heated in the heat exchange structure, or sCO2 directly enters the heating bin and is heated in the heating bin.

[0026] Compared with the prior art, some beneficial effects of the disclosed technical solution of the present invention include:

[0027] (1) The fluidized bed heat exchanger is divided into a mixing bin, a heating bin and a cooling bin, and uses the heating bin to heat sCO2 for external power generation; the thermochemical particles after heat exchange with sCO2 still have a relatively high temperature. At present, there is still no reliable high-temperature particle conveying device, so the cooling bin is needed to further cool the thermochemical particles. Subsequently, the low-temperature thermochemical particles can be transported and stored by a conveying device, avoiding the problem of difficult transportation of high-temperature thermochemical particles.

[0028] (2) The compartments in the fluidized bed heat exchanger are arranged in zones and separated from each other in the middle. Air chambers are respectively provided below each compartment. The mixing bin and the heating bin adopt air fluidization, which can promote the reaction of thermochemical particles with oxygen to release heat, and low-temperature flue gas with a lower oxygen content is used for cooling in the cooling bin to further accelerate the cooling rate of the thermochemical particles. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, so they should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1It is a schematic diagram of the internal structure of a heat exchanger.

[0031] Figure 2 It is a schematic diagram of the inflow and outflow of substances at the heat exchanger.

[0032] Figure 3 It is a schematic diagram of the composition of a heat exchange system.

[0033] In the above-mentioned drawings, the meanings of the various markings are as follows:

[0034] 1. Mixing bin; 2. Front partition wall; 3. Heating bin; 4. Heating structure; 5. Rear partition wall; 6. Cooling bin; 7. Cooling structure; 8. Waste heat recovery device; 9. Mixing bin air chamber; 10. Heating bin air chamber; 11. Cooling bin air chamber. Specific embodiments

[0035] The following further elaborates on this embodiment in conjunction with the drawings and specific examples.

[0036] In view of the deficiencies of existing fluidized bed heat exchangers, the following examples are optimized to overcome the defects in the prior art.

[0037] Example 1

[0038] As Figure 1 , Figure 2 shown, this example provides an sCO2 fluidized bed heat exchanger applicable to thermochemical particles. In the heat exchanger, a sequentially connected mixing bin 1, heating bin 3, and cooling bin 6 are formed. The mixing bin 1 is connected to a mixing bin air chamber 9, the heating bin 3 is connected to a heating bin air chamber 10, and the cooling bin 6 is connected to a cooling bin air chamber 11; external air is conveyed to the mixing bin air chamber 9 and the heating bin air chamber 10, and external flue gas with an oxygen content and temperature lower than the set value is introduced into the cooling bin air chamber 11.

[0039] In the heat exchanger disclosed in this example, by gradually pushing the high-temperature thermochemical particles forward, the sCO2 is heated in the heating bin 3, and the heated sCO2 can be transported and applied to a power generation system; while the high-temperature thermochemical particles can be cooled through the cooling bin 6, and after the temperature is reduced to the set temperature, they are transported backward and recycled.

[0040] The structure inside the heat exchanger can adopt various forms, and its structure is not uniquely limited. This example is optimized and adopts one of the feasible options: a front partition wall 2 and a rear partition wall 5 are provided inside the heat exchanger, and the inner cavity of the heat exchanger is isolated to form a mixing bin 1, a heating bin 3, and a cooling bin 6. When adopting the above scheme, a mixing bin 1 is formed between the front partition wall 2 and the inner wall surface of the heat exchanger, a heating bin 3 is formed between the front partition wall 2 and the rear partition wall 5, and a cooling bin 6 is formed between the rear partition wall 5 and the inner wall surface of the heat exchanger.

[0041] When heat exchange is carried out, heat exchange can be carried out in multiple bins simultaneously: the numbers of the mixing bin 1, the heating bin 3 and the cooling bin 6 are all greater than one. When adopting the above scheme, the arrangement of the mixing bin 1, the heating bin 3 and the cooling bin 6 is not uniquely limited, and can be set by arranging multiple lines in parallel, or by using other more methods.

[0042] When supplying fluidizing air into the heat exchanger, various schemes can be adopted. For example, the mixing bin 1 and the heating bin 3 can be fluidized with external air, while the cooling bin 6 is fluidized with low-temperature and low-oxygen flue gas. Its implementation structure is not uniquely limited. In this embodiment, optimization is carried out and one of the feasible options is adopted: the cooling bin 6 is connected to the waste heat recovery device 8. The external air is heated by the waste heat recovery device 8 and then transported into the mixing bin air chamber 9 and the heating bin air chamber 10, and a part of the flue gas discharged from the waste heat recovery device 8 is introduced into the cooling bin air chamber 11. When adopting the above scheme, the high-temperature flue gas discharged from the cooling bin 6 becomes low-temperature and low-oxygen flue gas after passing through the waste heat recovery device 8, and can be sent to the cooling bin 6 as fluidizing gas, improving the energy utilization efficiency of the system.

[0043] In some schemes, in order to enhance the heating effect of sCO2, the structure of the heating bin 3 can be optimized. Its structure is not uniquely limited. In this embodiment, optimization is carried out and one of the feasible options is adopted: a heating structure is arranged in the heating bin 3, and the heating structure is used to receive sCO2 and heat it. After heating, the sCO2 leaves the heating structure. When adopting the above scheme, the temperature of the sCO2 rises in the heater and is used for power generation and external transmission after rising.

[0044] Preferably, a heating surface is arranged on the heating structure, and the sCO2 can obtain heat from it to realize heating and temperature rise.

[0045] In order to improve the cooling effect on high-temperature thermochemical particles, in this embodiment, optimization is carried out and one of the feasible options is adopted: a cooling structure 7 for cooling thermochemical particles is arranged in the cooling bin 6. A cooling medium inlet and an outlet are arranged on the cooling structure 7. When the cooling medium enters the cooling structure 7, it exchanges heat with the thermochemical particles for cooling, and the cooled cooling medium leaves the cooling structure 7.

[0046] Preferably, a cooling surface is arranged on the cooling structure 7, and the high-temperature thermochemical particles can exchange heat and cool down from the cooling surface.

[0047] Preferably, in this embodiment, the cooling medium includes water or oil.

[0048] Embodiment 2

[0049] The content of the above Embodiment 1 discloses the structure of the heat exchanger. This embodiment discloses the heat exchange system, which will be described below.

[0050] As Figure 3 shown, the sCO2 fluidized bed heat exchange system applicable to thermochemical particles includes a low-temperature thermochemical particle storage tank, a thermochemical particle reduction device, a collector, a high-temperature thermochemical particle storage tank, and a fluidized bed heat exchanger. The sCO2 in the low-temperature state is heated to the high-temperature state after entering the fluidized bed heat exchanger.

[0051] Preferably, the collector uses solar energy to heat the thermochemical particles.

[0052] The above heat exchange system enables the thermochemical particles to form a flowing cycle, which can switch during the endothermic and exothermic processes, thereby realizing the heating treatment of sCO2.

[0053] Example 3

[0054] This example discloses a method for heating sCO2, which will be described below.

[0055] The sCO2 fluidized bed heat exchange method applicable to thermochemical particles uses the heat exchange system described above and includes:

[0056] Heat storage stage: The oxidized low-temperature thermochemical particles enter the thermochemical particle reduction device for reduction, and then enter the collector to be heated to a set temperature to become high-temperature thermochemical particles;

[0057] Energy release stage: The high-temperature thermochemical particles enter the fluidized bed heat exchanger to heat sCO2. The heat exchange process includes the physical sensible heat of the high-temperature thermochemical particles and the heat generated by the reaction of the high-temperature thermochemical particles with the fluidizing air. The thermochemical particles after heat release are then transported backward for heat storage again.

[0058] The flow circulation paths of the high-temperature thermochemical particles and sCO2 in the heat exchanger are different. This example is optimized and one feasible option is adopted: In the energy release stage, the high-temperature thermochemical particles enter from the mixing chamber 1, are mixed evenly under the action of the fluidizing air in the mixing chamber 1, and then enter the heating chamber 3; The high-temperature thermochemical particles in the heating chamber 3 heat sCO2 through physical sensible heat and chemical heat; The high-temperature thermochemical particles after heat release enter the cooling chamber 6 for cooling until they are reduced to the set temperature and then transported backward. When the above scheme is adopted, sCO2 is connected to the external heat exchange structure and is heated in the heat exchange structure, or sCO2 directly enters the heating chamber 3 and is heated in the heating chamber 3.

[0059] The above are the implementation manners listed in this embodiment. However, this embodiment is not limited to the above optional implementation manners. Those skilled in the art can arbitrarily combine the above manners to obtain many other implementation manners. Anyone can obtain various other forms of implementation manners under the inspiration of this embodiment. The above specific implementation manners should not be construed as limiting the protection scope of this embodiment. The protection scope of this embodiment shall be defined by the claims.

Claims

1. An sCO2 fluidized bed heat exchanger applicable to thermochemical particles, characterized in that: A mixing chamber (1), a heating chamber (3) and a cooling chamber (6) which are sequentially connected are formed inside the heat exchanger. The mixing chamber (1) is connected to a mixing chamber air chamber (9), the heating chamber (3) is connected to a heating chamber air chamber (10), and the cooling chamber (6) is connected to a cooling chamber air chamber (11). External air is conveyed to the mixing chamber air chamber (9) and the heating chamber air chamber (10), and external flue gas with an oxygen content and temperature lower than the set values is introduced into the cooling chamber air chamber (11).

2. The sCO2 fluidized bed heat exchanger applicable to thermochemical particles according to claim 1, characterized in that: A front partition wall (2) and a rear partition wall (5) are arranged inside the heat exchanger, and the inner cavity of the heat exchanger is partitioned to form a mixing chamber (1), a heating chamber (3) and a cooling chamber (6).

3. The sCO2 fluidized bed heat exchanger applicable to thermochemical particles according to claim 1 or 2, characterized in that: The numbers of the mixing chamber (1), the heating chamber (3) and the cooling chamber (6) are all greater than one.

4. The sCO2 fluidized bed heat exchanger applicable to thermochemical particles according to claim 1, wherein: The cooling chamber (6) is connected to a waste heat recovery device (8). External air is heated by the waste heat recovery device (8) and then conveyed into the mixing chamber air chamber (9) and the heating chamber air chamber (10), and part of the flue gas discharged from the waste heat recovery device (8) is introduced into the cooling chamber air chamber (11).

5. The sCO2 fluidized bed heat exchanger applicable to thermochemical particles according to claim 1, characterized in that: A heat-receiving structure is arranged inside the heating chamber (3), and the heat-receiving structure is used to receive sCO2 and heat it. After heating, the sCO2 leaves the heat-receiving structure.

6. The sCO2 fluidized bed heat exchanger applicable to thermochemical particles according to claim 1, wherein: A cooling structure (7) for cooling the thermochemical particles is arranged inside the cooling chamber (6). A cooling medium inlet and an outlet are arranged on the cooling structure (7). When the cooling medium enters the cooling structure (7), it exchanges heat with the thermochemical particles for cooling, and the cooled cooling medium leaves the cooling structure (7).

7. The sCO2 fluidized bed heat exchanger applicable to thermochemical particles according to claim 6, characterized in that: The cooling medium includes water or oil.

8. sCO2 fluidized bed heat exchange system applicable to thermochemical particles, characterized in that: It includes a low-temperature thermochemical particle storage tank, a thermochemical particle reduction device, a collector, a high-temperature thermochemical particle storage tank and a fluidized bed heat exchanger. Low-temperature sCO2 enters the fluidized bed heat exchanger and is heated to obtain high-temperature sCO2.

9. The sCO2 fluidized bed heat exchange method applicable to thermochemical particles, using the heat exchange system described in claim 8, is characterized in that, including Heat storage stage: The oxidized low-temperature thermochemical particles enter the thermochemical particle reduction device for reduction, and then enter the collector to be heated to a set temperature to become high-temperature thermochemical particles. Energy release stage: The high-temperature thermochemical particles enter the fluidized bed heat exchanger to heat sCO2. The heat exchange process includes the physical sensible heat of the high-temperature thermochemical particles and the heat generated by the reaction of the high-temperature thermochemical particles with the fluidizing air. After heat release, the thermochemical particles are conveyed backward to re-perform heat storage.

10. The sCO2 fluidized bed heat exchange method applicable to thermochemical particles according to claim 9, characterized in that: In the energy release stage, the high-temperature thermochemical particles enter from the mixing chamber (1), are evenly mixed under the action of the fluidizing air in the mixing chamber (1), and then enter the heating chamber (3). In the heating chamber (3), the high-temperature thermochemical particles heat sCO2 through physical sensible heat and chemical heat. The high-temperature thermochemical particles after heat release enter the cooling chamber (6) for cooling until the temperature is reduced to the set temperature and then conveyed backward.

Images