Compact supercritical carbon dioxide recompression cycle power device

Abstract

The invention provides a compact type supercritical carbon dioxide recompression cycle power device, which relates to a supercritical carbon dioxide cycle power technology, and adopts the structure that a main compressor, a recompressor and a turbine are coaxially arranged in a structure consisting of a first cylinder body, a high-temperature heat regenerator and a second cylinder body; rotation kinetic energy of the rotor can be directly utilized to drive the components to rotate synchronously, energy conversion loss is effectively reduced, equipment composition in the system is simplified, and maintenance cost is reduced. A low-temperature heat regenerator, a main compressor, a re-compressor and a cooler of the re-compressor are highly integrated in the first cylinder body; a turbine and a heat source are highly integrated in a second cylinder body, and a high-temperature heat regenerator serves as a structural center piece to be connected with the cylinder bodies, so that the size and the occupied area of the power device are remarkably reduced; the working medium is circulated through the first circulation structure and the second circulation structure, the requirement for an external pipeline is eliminated, the flow resistance and the leakage risk are reduced, and the space utilization rate is greatly increased.

Description

Technical Field

[0001] The present invention relates to the technical field of supercritical carbon dioxide cycle power, and in particular to a compact supercritical carbon dioxide recompression cycle power device. Background Art

[0002] The supercritical carbon dioxide (sCO2) energy conversion system combines CO2 with the Brayton cycle, using supercritical CO2 as the working fluid. The sCO2 simple cycle primarily consists of a heat source, turbine, generator, regenerator, cooler, compressor, valves, and piping. Its energy conversion follows the Brayton cycle, consisting of a constant-pressure heat absorption process in the heat source, an isentropic expansion process in the turbine, a constant-pressure heat release process in the cooler, and an isentropic compression process in the compressor. A regenerator is also used to recover heat from turbine exhaust gas. Combined with the high density and compressibility of supercritical CO2 near its critical point, this energy conversion system achieves the advantages of low power consumption and high output.

[0003] In order to further improve the thermal efficiency of the system and reduce the impact of the pinch point phenomenon in the regenerator, scholars proposed the sCO2 recompression cycle, which adds a recompressor to the simple cycle and divides the regenerator into a low-temperature regenerator and a high-temperature regenerator. After the outlet of the hot side of the low-temperature regenerator, the sCO2 working fluid is divided into two streams. One stream flows through the cooler and the main compressor and then enters the cold side of the low-temperature regenerator. The other stream flows directly into the recompressor without being cooled. After the working fluid flows out, it merges with the sCO2 working fluid at the outlet of the cold side of the low-temperature regenerator and then flows into the cold side of the high-temperature regenerator. The use of the working fluid diversion method avoids the heat transfer pinch point problem that is prone to occur at the cold end of the regenerator and improves the energy transfer efficiency of the heat exchange equipment. At the same time, the working fluid flowing through the recompressor is not cooled, so that the working fluid temperature entering the heat source is higher than that of the simple cycle, which reduces the heat absorption temperature difference loss of the working fluid in the heat source, increases the temperature of the hot end of the system, and improves the overall thermal efficiency of the system.

[0004] In existing implementation methods of sCO2 recompression technology, each device is arranged separately, and the working fluid is transported between devices through pipelines. This leads to complex system pipelines, resulting in a long gas flow path. The long pipeline setting increases flow resistance and heat loss. In addition, there are many interfaces between pipelines and equipment, and problems such as working fluid leakage at pipeline connections, pipeline vibration, and excessive thermal expansion may occur during operation. Traditional systems use a split layout: the turbine, main compressor, and recompressor are usually independent devices. The turbine drives the generator to generate electricity, and then drives the electric motor through power cables to drive the main compressor and recompressor respectively. This layout requires energy to undergo multiple conversions from "mechanical energy → electrical energy → mechanical energy", which greatly reduces the net output power of the system. Therefore, how to simplify the system pipeline and improve the overall compactness through equipment structure optimization and layout adjustment is of great significance to the sCO2 recompression system. Summary of the Invention

[0005] The object of the present invention is to provide a compact supercritical carbon dioxide recompression cycle power device, which can solve the problems raised by the above-mentioned background technology in view of the shortcomings of the existing technology.

[0006] The technical solution of the present invention is achieved as follows:

[0007] The invention provides a compact supercritical carbon dioxide recompression cycle power device, comprising a high-temperature regenerator, a first cylinder body, a second cylinder body and a rotating shaft, wherein the first cylinder body and the second cylinder body are respectively installed on both sides of the high-temperature regenerator, an axial hole is opened in the high-temperature regenerator, the rotating shaft extends outward after passing through the axial hole, and the two ends of the rotating shaft are respectively rotatably connected to the inner wall of the first cylinder body or the second cylinder body; a low-temperature regenerator connected to the high-temperature regenerator is installed in the first cylinder body, a main compressor connected to the rotating shaft is installed in the first cylinder body, a recompressor is installed on the outer wall of the rotating shaft located between the main compressor and the high-temperature regenerator, a heat source connected to the high-temperature regenerator is installed in the second cylinder body, a turbine is installed on the end of the rotating shaft placed in the second cylinder body, a first circulation structure for gas circulation is provided in the first cylinder body, a second circulation structure for gas circulation is provided in the second cylinder body, and a cooler is installed in the first cylinder body.

[0008] In some technical solutions of the present invention, the first cylinder body includes a first inner shell and a first outer shell with both ends open, one end of the first outer shell is closed, and the other end has an opening; the first inner shell is sleeved on the outer wall of the high-temperature regenerator, the first outer shell is sleeved on the outer wall of the first inner shell, and the first circulation structure is installed between the first inner shell and the first outer shell; a guide channel is opened on the side of the first inner shell close to the recompressor, and the first circulation structure is connected to the guide channel.

[0009] In some technical solutions of the present invention, a main compressor stator blade structure matching the main compressor is installed in the first inner shell, and a re-compressor stator blade structure matching the re-compressor is installed in the first inner shell. A conical guide structure for guiding the gas flow is provided between the main compressor stator blade structure and the re-compressor stator blade structure, and an installation port adapted to the rotating shaft is provided on the guide structure.

[0010] In some technical solutions of the present invention, the second cylinder body includes a second inner shell with both ends open and a second outer shell, one end of the second outer shell is closed and the other end has an opening; the second inner shell is sleeved on the outer wall of the high-temperature regenerator, and the second outer shell is sleeved on the outer wall of the second inner shell. The second circulation structure is installed between the second inner shell and the second outer shell, and the inner wall of the second inner shell is provided with a turbine stator structure matching the turbine.

[0011] In some technical solutions of the present invention, a plurality of semi-annular hollow sandwich structures are sequentially provided in the first inner shell or the second inner shell along the axial direction thereof.

[0012] In some technical solutions of the present invention, there are two groups of coolers, which are spliced ​​together and arranged around the outside of the main compressor; the cooler includes a first bushing and a second bushing, the first bushing is installed in the second bushing, and several cooling structures are installed between the first bushing and the second bushing. The inner cavity of the cooling structure is provided with a zigzag heat exchange flow channel, and the outer side wall of the second bushing is provided with two water tanks that are respectively connected to the inner cavity of the cooling structure, one of the water tanks is provided with two cooling water inlet pipes on the outer side wall, and the other water tank has two cooling water outlet pipes on the outer fan blades, and a zigzag gas flow channel is provided between any two adjacent cooling structures.

[0013] In some technical solutions of the present invention, the low-temperature regenerator is arranged on the periphery of the re-compressor, the small diameter end of the low-temperature regenerator faces the side of the high-temperature regenerator, a low-temperature gas inlet and outlet are provided on the large diameter end face of the low-temperature regenerator, and the outer wall of the low-temperature regenerator has a first low-temperature gas flow channel arranged in a tortuous manner and connected to the low-temperature gas inlet and outlet; a high-temperature gas inlet and outlet are provided on the large diameter inner wall of the low-temperature regenerator, and the outer wall of the low-temperature regenerator has a first high-temperature gas flow channel arranged in a tortuous manner and connected to the high-temperature gas inlet and outlet, and the first high-temperature gas flow channel is located between any two adjacent first low-temperature gas flow channels.

[0014] In some technical solutions of the present invention, there are two groups of high-temperature regenerators, which are connected to each other to form a circular ring shape; the high-temperature regenerator includes several surrounding high-temperature gas circulation structures, and a zigzag second low-temperature gas flow channel is provided between any two adjacent high-temperature gas circulation structures. A zigzag second high-temperature gas flow channel is provided in the inner cavity of the high-temperature gas circulation structure, and two inlet and outlet channels are provided on the outer wall of the high-temperature gas circulation structure, and both inlet and outlet channels are connected to the second high-temperature gas flow channel.

[0015] In some technical solutions of the present invention, the heat source includes two groups of reactor pressure vessels spliced ​​together, which form a ring-shaped structure after being spliced ​​together. A chamber is opened on the outer wall of the reactor pressure vessel, one end of the reactor pressure vessel is opened with an air inlet connected to the chamber, and the other end of the reactor pressure vessel is opened with an air outlet connected to the chamber. The chamber is filled with spherical fuel elements, and two groups of control ball guide tubes are installed in the chamber, and both ends of the control ball guide tube pass through the outer wall of the reactor pressure vessel and extend outward.

[0016] Compared with the prior art, the present invention has at least the following advantages or beneficial effects: the main compressor, recompressor, and turbine are coaxially arranged in a structure consisting of a first cylinder, a high-temperature regenerator, and a second cylinder. The kinetic energy of the rotor rotation can be directly used to drive the above components to rotate synchronously, effectively reducing energy conversion losses. There is no need to set up equipment such as a main compressor drive motor, a recompressor drive motor, and power cables, which effectively improves the system's energy conversion efficiency, streamlines the equipment structure in the system, and reduces maintenance costs; the low-temperature regenerator, main compressor, recompressor, and cooler are highly integrated in the first cylinder; the turbine and heat source (such as a nuclear reactor) are highly integrated in the second cylinder, and the high-temperature regenerator serves as a structural centerpiece connecting the cylinders, giving the entire power unit a non-uniform cylindrical appearance, significantly reducing its volume and footprint; the annular cavity interlayer space between the first / second inner shell and the first / second outer shell is used to respectively construct the first circulation structure and the second circulation structure. These flow channels serve as both working medium circulation channels and part of the supporting shell, eliminating the need for external pipes, reducing flow resistance and leakage risks, and greatly improving space utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the overall structure of a compact supercritical carbon dioxide recompression cycle power plant;

[0018] Figure 2 This is a schematic diagram of the exploded structure of a compact supercritical carbon dioxide recompression cycle power plant;

[0019] Figure 3 This is a schematic diagram of the working fluid flow of a compact supercritical carbon dioxide recompression cycle power plant;

[0020] Figure 4 Schematic diagram of the three-dimensional structure of the cooler;

[0021] Figure 5 Schematic diagram of the flow structure of cooling water in the cooler;

[0022] Figure 6 Schematic diagram of the supercritical carbon dioxide flow structure in the intercooler;

[0023] Figure 7 Schematic diagram of the three-dimensional structure of the second high-temperature gas flow channel in the high-temperature regenerator;

[0024] Figure 8 Schematic diagram of the three-dimensional structure of the second low-temperature gas flow channel in the high-temperature regenerator;

[0025] Figure 9 Schematic diagram of the three-dimensional structure of the first high-temperature gas flow channel in the low-temperature regenerator;

[0026] Figure 10Schematic diagram of the three-dimensional structure of the first low-temperature gas flow channel in the low-temperature regenerator;

[0027] Figure 11 Schematic diagram of the three-dimensional structure of the heat source;

[0028] Figure 12 Schematic diagram of the three-dimensional structure after the first inner shell and the second inner shell are combined;

[0029] Figure 13 It is a schematic diagram of the three-dimensional structure after the first shell and the second shell are combined.

[0030] Reference numerals:

[0031] 1. Second outer shell; 2. High-temperature regenerator; 3. First inner shell; 4. Rotating shaft; 5. Cooling water inlet pipe; 6. Cooling water outlet pipe; 7. Control ball guide tube; 8. First outer shell; 9. Turbine; 10. Recompressor; 11. Main compressor; 12. Cooler; 13. Heat source; 14. Water tank; 15. Low-temperature regenerator; 16. Second inner shell; 17. Second circulation structure; 18. First circulation structure; 19. Flow guide structure; 20. Heat exchange flow channel; 21. Gas outlet; 22. Gas flow channel; 23. Second low-temperature gas flow channel; 24. Inlet and outlet channels; 25. Low-temperature gas inlet and outlet; 26. Second high-temperature gas flow channel; 27. First high-temperature gas flow channel; 28. Air inlet; 29. ​​Air outlet; 30. Main compressor stator blade structure; 31. Recompressor stator blade structure; 32. Turbine stator blade structure; 33. First low-temperature gas flow channel; 34. High-temperature gas inlet and outlet. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0034] Example

[0035] The present invention provides a compact supercritical carbon dioxide recompression cycle power device, the overall shape of which is a non-uniform cylindrical shape, such as Figure 1 、 Figure 2As shown, its specific structure includes a high-temperature regenerator 2, a first cylinder body, a second cylinder body and a rotating shaft 4. The first cylinder body and the second cylinder body are both divided into an upper cylinder head and a lower cylinder head to facilitate equipment installation and maintenance operations; the first cylinder body and the second cylinder body are respectively installed on both sides of the high-temperature regenerator 2, and an axial hole is opened in the high-temperature regenerator 2. The rotating shaft 4 extends outward after passing through the axial hole. The two ends of the rotating shaft 4 are respectively connected to the inner wall of the first cylinder body or the second cylinder body through bearings to achieve rotational connection; a low-temperature regenerator 15 connected to the high-temperature regenerator 2 is installed in the first cylinder body, and a main compressor 11 connected to the rotating shaft 4 is installed in the first cylinder body. The rotor of the main compressor 11 contains a multi-stage impeller, which compresses the supercritical carbon dioxide working fluid to achieve pressure increase and drive the working fluid flow.

[0036] The re-compressor 10 is installed on the outer wall of the rotating shaft 4 between the main compressor 11 and the high-temperature regenerator 2 for secondary compression of the working medium. A heat source 13 connected to the high-temperature regenerator 2 is installed in the second cylinder. The end of the rotating shaft 4 placed in the second cylinder is installed with a turbine 9. The turbine 9 also includes a multi-stage impeller, which uses high-temperature and high-pressure working medium to drive the turbine 9 impeller to rotate, converting the internal energy of the working medium into rotational mechanical energy, driving the integrated rotating shaft 4 to rotate, driving the back-end equipment such as the generator, and also driving the impellers of the main compressor 11 and the re-compressor 10 to rotate, so as to realize the circulation of the working medium in the above structure. The present technology solves the problem in the prior art that the main compressor 11, the re-compressor 10 and the turbine 9 are arranged separately by an electric motor. The main compressor 11 and the re-compressor 10 are driven by the turbine 9 to rotate, thereby compressing the working fluid. The electricity for the turbine 9 comes from the generator driven by the turbine 9, and the energy undergoes the conversion from mechanical energy to electrical energy to mechanical energy. There are problems such as energy conversion loss and mechanical friction loss between multiple devices. In this structure, the main compressor 11, the re-compressor 10, and the turbine 9 are coaxially arranged in a structure composed of the first cylinder body, the high-temperature regenerator 2, and the second cylinder body. The kinetic energy of the rotor rotation can be directly used to drive the above components to rotate synchronously, effectively reducing the energy conversion loss. There is no need to set up the main compressor 11 drive motor, the re-compressor 10 drive motor, the power cables and other equipment, which effectively improves the system energy conversion efficiency, simplifies the equipment structure in the system, and reduces the maintenance cost.

[0037] A first circulation structure 18 for gas circulation is provided in the first cylinder, and a second circulation structure 17 for gas circulation is provided in the second cylinder. The first circulation structure 18 and the second circulation structure 17 are used for the working medium to circulate among the coaxially arranged first cylinder, second cylinder, main compressor 11, recompressor 10, low-temperature regenerator 15, high-temperature regenerator 2 and turbine 9; a cooler 12 is installed in the first cylinder for cooling the working medium in a high-temperature state to achieve efficient utilization of the working medium.

[0038] The sCO2 working medium circulation process: After being heated by the heat source 13, the sCO2 working medium forms a high-temperature, high-pressure working medium. This high-temperature, high-pressure working medium rushes into the impeller of the turbine 9, driving the turbine 9 to rotate at high speed. After undergoing multiple stages of energy conversion in the impeller, the working medium's enthalpy decreases. After exiting the turbine 9 impeller, the exhaust gas flows through the second outer casing 1, where it is directed into the second circulation structure 17 (annular cavity) between the second inner casing 16 and the second outer casing 1. The working medium then flows axially along the second circulation structure 17, radially flowing from the side of the high-temperature regenerator 2. Heat is recovered in the high-temperature regenerator 2 to heat the working medium entering the heat source 13. The working medium flows out of the side outlet of the high-temperature regenerator 2, is directed by the first outer casing 8, and flows into the side of the low-temperature regenerator 15. Within the low-temperature regenerator 15, the working medium generally flows axially. At the other end of the low-temperature regenerator 15, the working medium splits into two streams through the two side outlets. One stream flows into the impeller of the recompressor 10, where it is compressed and then flows into the high-temperature regenerator 2. Another stream of working fluid flows through the cooler 12 arranged on the periphery of the main compressor 11 through the first circulation structure 18, and the temperature is further reduced. Then, the working fluid is guided axially by the first outer shell 8 and the first inner shell 3 to flow into the impeller of the main compressor 11. After the main compressor 11 does work, the working fluid pressure is greatly increased. It flows into the low-temperature regenerator 15 again through the channel between the first inner shell 3 and the rotating shaft 4, and then further flows into the inlet of the high-temperature regenerator 2. At the inlet of the high-temperature regenerator 2, it merges with the working fluid at the outlet of the re-compressor 10. After being heated by the high-temperature regenerator 2, it enters the heat source 13 to absorb heat, and the cycle repeats.

[0039] In some technical solutions of the present invention, the first cylinder includes a first inner shell 3 and a first outer shell 8, both ends of which are open. One end of the first outer shell 8 is closed to form a pressure boundary, and the other end has an opening. The first inner shell 3 is mounted on the outer wall of the high-temperature regenerator 2, and the first outer shell 8 is mounted on the outer wall of the first inner shell 3. The first circulation structure 18 is installed between the first inner shell 3 and the first outer shell 8. A guide channel is opened on the side of the first inner shell 3 close to the recompressor 10, and the first circulation structure 18 is connected to the guide channel. The first circulation structure 18 is installed in the interlayer space formed between the first outer shell 8 and the first inner shell 3 to construct a high-temperature flow channel, so that the working medium circulates in the space formed by the first cylinder, the high-temperature regenerator 2, and the second cylinder.

[0040] In some technical solutions of the present invention, a main compressor stator blade structure 30 matching the main compressor 11 is installed within the first inner shell 3, and a recompressor stator blade structure 31 matching the recompressor 10 is installed within the first inner shell 3. The main compressor stator blade structure 30 and the recompressor stator blade structure 31 regulate the flow direction of the working medium. A conical flow guide structure 19 for guiding gas flow is provided between the main compressor stator blade structure 30 and the recompressor stator blade structure 31. The flow guide structure 19 has a mounting opening adapted for the rotating shaft 4. A sealing structure is provided on the wall where the conical flow guide contacts the rotating shaft 4 to reduce leakage of the working medium at the shaft gap. The inner and outer wall surfaces of the first inner shell 3 and the second inner shell 16 are both smoothed to reduce frictional resistance of the working medium.

[0041] In some technical solutions of the present invention, the second cylinder includes a second inner shell 16 open at both ends and a second outer shell 1. The second outer shell 1 is closed at one end to form a pressure boundary and has an opening at the other end. The second inner shell 16 is sleeved onto the outer wall of the high-temperature regenerator 2, and the second outer shell 1 is sleeved onto the outer wall of the second inner shell 16. The second circulation structure 17 is installed between the second inner shell 16 and the second outer shell 1. The second inner shell 16 and the second outer shell 1 are each composed of two half-shell structures spliced ​​together.

[0042] A turbine stator blade structure 32 matching the turbine 9 is installed in the second inner shell 16 to adjust the flow direction of the working medium.

[0043] In some technical solutions of the present invention, several semi-annular hollow sandwich structures are sequentially arranged along the axial direction within the first inner shell 3. Because working fluid flows through both the inner and outer annular surfaces of the inner shell, radial heat conduction through the inner shell must be minimized. Therefore, hollow sandwich structures are used in the first inner shell 3 and the second inner shell 16. The hollow sandwich structures are semi-circular cavity structures with a vacuum or low thermal conductivity material inside to minimize radial heat conduction and reduce heat loss.

[0044] Preferably, the first inner shell 3 located at the main compressor 11 and recompressor 10, and the second inner shell 16 located at the turbine 9, due to their relatively complex structures, can be formed by casting, additive manufacturing, or other methods. The second inner shell 16 located at the heat source 13 has a uniform structure and is a multi-layer thin shell, which can be formed by vacuum diffusion welding, brazing, additive manufacturing, or other methods. The inner walls of the first outer shell 8 and the second outer shell 1 also have smooth surfaces to reduce friction. Because the first and second outer shells 8 and 1 need to isolate the internal high-temperature and high-pressure working fluid from the external environment, their walls are relatively thick and can be formed by casting, forging, machining, or other methods.

[0045] In some technical solutions of the present invention, there are two groups of coolers 12. After being spliced ​​together, the two coolers 12 are arranged around the periphery of the main compressor 11. The outer shape is a conical ring, and a single cooler 12 occupies a 180-degree space. The cooler 12 includes a first bushing and a second bushing. The first bushing is installed in the second bushing. Several cooling structures are installed between the first bushing and the second bushing. The inner cavity of the cooling structure is provided with a zigzag heat exchange flow channel 20. The outer wall of the second bushing is provided with two water tanks 14 respectively connected to the inner cavity of the cooling structure. Two cooling water inlet pipes 5 are provided on the outer wall of one water tank 14, and two cooling water outlet pipes 6 are provided on the outer fan blade of the other water tank 14. A zigzag gas channel 22 is provided between any two adjacent cooling structures. The cooling structure and the gas channel 22 are arranged periodically in sequence to achieve an efficient and compact heat exchange effect. Cooling water is fed from the cooling water inlet pipe 5 located at the large diameter end of the cooler 12 into the annularly arranged water tank 14. The annular cavity structure within the water tank 14 distributes the cooling water. After diversion, the cooling water radially flows into each layer of the cooling structure, absorbs heat through the zigzag heat exchange channel 20, and then flows into another water tank 14 for collection. The collected cooling water flows out from the cooling water outlet pipe 6 located at the small diameter end of the cooler 12. The sCO2 working medium enters the zigzag heat exchange channel 20 from the small diameter end of the cooler 12 to achieve heat transfer, and then flows out axially from the gas outlet 21 located at the large diameter end of the cooler 12. The cooling water and sCO2 working medium flow in counter-currents within the heat exchange channel 20 within the cooler 12 to achieve a higher heat exchange temperature difference, thereby reducing the volume of the cooler 12.

[0046] Preferably, the heat exchange flow channel 20 is a continuous microchannel, such as a straight, zigzag, circuitous, or S-shaped channel; or a discontinuous channel, such as a wing-shaped fin, diamond-shaped fin, or cylindrical fin; or an irregular channel formed by additive manufacturing. The inner wall of the channel can be provided with various one-dimensional, two-dimensional, or three-dimensional heat transfer enhancement structures. The cooler 12 can also be formed using a compact micro-shell-and-tube structure, formed by brazing or welding tiny heat transfer tubes to a tube sheet.

[0047] In some technical solutions of the present invention, the low-temperature regenerator 15 is arranged on the periphery of the re-compressor 10, and its outer shape is a conical ring. A single low-temperature regenerator 15 occupies 180 degrees of the first inner shell 3. The small diameter end of the low-temperature regenerator 15 faces the side of the high-temperature regenerator 2. A low-temperature gas inlet and outlet 25 is provided on the large-diameter end face of the low-temperature regenerator 15. The outer wall of the low-temperature regenerator 15 has a first low-temperature gas flow channel 33 that is arranged in a tortuous manner and connected to the low-temperature gas inlet and outlet 25; a high-temperature gas inlet and outlet 34 is provided on the large-diameter inner wall of the low-temperature regenerator 15. The outer wall of the low-temperature regenerator 15 has a first high-temperature gas flow channel 27 that is arranged in a tortuous manner and connected to the high-temperature gas inlet and outlet 34. The first high-temperature gas flow channel 27 is located between any two adjacent first low-temperature gas flow channels 33. The working fluid on both the hot and cold sides of the low-temperature regenerator 15 is sCO2, but the working fluid mass flow rates are different. The two sCO2 working fluids of different temperatures sequentially pass through the periodically arranged first high-temperature gas flow channels 27 and first low-temperature gas flow channels 33 at intervals to achieve efficient and compact heat exchange. The high-temperature sCO2 working fluid flows in from the low-temperature gas inlet and outlet 25 on the side of the small-diameter end of the low-temperature regenerator 15. After heat exchange through the first high-temperature gas flow channels 27, it is divided into two streams at the large-diameter end of the low-temperature regenerator 15 and flows out through the inner and outer wall outlets. The flow ratio of the two working fluids can be adjusted by adjusting the flow area of ​​the inner and outer wall outlets. In the low-temperature sCO2 working fluid heat exchange layer, the low-temperature sCO2 working fluid flows axially into the low-temperature gas inlet and outlet 25 at the large-diameter end of the low-temperature regenerator 15, transfers heat through the zigzag first low-temperature gas flow channels 33, and then flows out axially. The low-temperature sCO 2 working medium and the high-temperature sCO 2 working medium flow in counter-currents in the first low-temperature gas flow channel 33 and the first high-temperature gas flow channel 27 to achieve a higher heat exchange temperature difference and thus reduce the volume of the low-temperature regenerator 15 .

[0048] The flow is split through the low-temperature regenerator 15, so that the working fluid flow rates on the cold and hot sides of the low-temperature regenerator 15 are different. Since the sCO2 working fluid on the low-temperature side has a lower temperature, its working fluid state is close to the pseudo-critical state, and thus has a larger specific heat capacity value. By reducing the mass flow rate, the heat capacity (i.e., the product of specific heat capacity and mass flow rate) can be effectively controlled from increasing too quickly, thereby avoiding the pinch point phenomenon inside the heat exchanger, which causes a decrease in heat exchange efficiency.

[0049] Preferably, the first high-temperature gas flow channel 27 and the first low-temperature gas flow channel 33 are continuous microchannels, such as straight, zigzag, circuitous, and S-shaped channels, as well as discontinuous channels such as wing-shaped fins, diamond-shaped fins, and cylindrical fins, and irregular channels formed by additive manufacturing. The inner walls of the channels can be provided with various one-dimensional, two-dimensional, and three-dimensional heat transfer enhancement structures. The low-temperature regenerator 15 can be formed using a compact micro-shell-and-tube structure, formed by brazing or welding tiny heat transfer tubes to a tube sheet.

[0050] In some technical solutions of the present invention, the high-temperature regenerators 2 are arranged in two groups. When connected, they form a circular ring, with each regenerator 2 being semicircular. The high-temperature regenerators 2 include several surrounding high-temperature gas circulation structures. Between any two adjacent high-temperature gas circulation structures, a zigzag second low-temperature gas flow channel 23 is provided. Both ends of the second low-temperature gas flow channel 23 are open and fan-shaped on the end surface of the circle surrounding the high-temperature regenerator 2. A zigzag second high-temperature gas flow channel 26 is provided within the inner cavity of the high-temperature gas circulation structure. Two inlet and outlet channels 24 are provided on the outer wall of the high-temperature gas circulation structure. Both inlet and outlet channels 24 communicate with the second high-temperature gas flow channel 26. The air inlet direction of the second low-temperature gas flow channel 23 is perpendicular to the air inlet direction of the second high-temperature gas flow channel 26. The working medium on both sides of the high-temperature regenerator 2 is sCO2. The low-temperature sCO2 and high-temperature sCO2 flow media sequentially pass through the periodically arranged second low-temperature gas flow channels 23 and second high-temperature gas flow channels 26, achieving efficient heat exchange. The working fluids on both sides flow axially, but in opposite directions. After passing through turbine 9, the high-temperature sCO2 working fluid flows through inlet and outlet channels 24 located on the outer annular surface of high-temperature regenerator 2, exchanges heat through a zigzag second high-temperature gas flow channel 26, and then exits through inlet and outlet channels 24 on the outer annular surface of high-temperature regenerator 2. On the other side, the low-temperature sCO2 working fluid, compressed by recompressor 10, and the low-temperature sCO2 working fluid, heated by low-temperature regenerator 15, merge at the low-temperature end surface of high-temperature regenerator 2 and flow into the second low-temperature gas flow channel 23. They exchange heat through the zigzag second low-temperature gas flow channel 23 and then exit through the other end of the second low-temperature gas flow channel 23 within high-temperature regenerator 2. Through the structural arrangement, the inlet and outlet channels 24 for the high-temperature working fluid are both located on the outer annular surface of the regenerator, while the flow ports for the low-temperature working fluid are located on the end surfaces of high-temperature regenerator 2, achieving efficient and compact heat exchange. The flow ports are connected to the second low-temperature gas flow channel 23.

[0051] In some technical solutions of the present invention, heat source 13 comprises two sets of reactor pressure vessels joined together to form a ring-shaped structure. A chamber is defined on the outer wall of each reactor pressure vessel. An air inlet 28 communicating with the chamber is defined at one end of the reactor pressure vessel, and an air outlet 29 communicating with the chamber is defined at the other end of the reactor pressure vessel. The chamber is filled with spherical fuel elements and is equipped with two sets of control ball guide tubes 7, each of which extends outward through the outer wall of the reactor pressure vessel. Heat source 13 provides power for a direct-cycle nuclear energy conversion system using sCO2 as a working fluid. Heat source 13 can employ a gas-cooled reactor and primarily comprises a reactor pressure vessel, spherical fuel elements, and reaction rate control balls. After absorbing heat in the high-temperature regenerator 2, the sCO2 working medium flows into the reactor through the air inlet 28 at the end of the pressure vessel. The nuclear fuel releases a large amount of heat through the fission reaction, heating the sCO2 working medium. After heating, the working medium, at a high temperature and high pressure, flows out of the reactor through the air outlet 29. During operation, the nuclear reaction rate of the gas-cooled reactor needs to be controlled. A control ball conduit 7 is installed within the reactor pressure vessel. When the nuclear reaction rate needs to be slowed, the control ball is pushed into the conduit to absorb neutrons, slowing the chain fission rate and controlling the rate of heat release from the nuclear reaction. When the nuclear reaction rate does not need to be slowed, the control ball is pushed out of the conduit and out of the reactor pressure vessel.

[0052] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A compact supercritical carbon dioxide recompression cycle power plant, characterized in that: The invention comprises a high-temperature regenerator (2), a first cylinder body, a second cylinder body and a rotating shaft (4), wherein the first cylinder body and the second cylinder body are respectively installed on both sides of the high-temperature regenerator (2), an axial hole is opened in the high-temperature regenerator (2), the rotating shaft (4) extends outward after passing through the axial hole, and the two ends of the rotating shaft (4) are respectively rotatably connected to the inner wall of the first cylinder body or the second cylinder body; a low-temperature regenerator (15) connected to the high-temperature regenerator (2) is installed in the first cylinder body, and a main pressure regenerator (15) connected to the rotating shaft (4) is installed in the first cylinder body. A compressor (11) is provided, a recompressor (10) is installed on the outer wall of a rotating shaft (4) located between the main compressor (11) and the high-temperature regenerator (2), a heat source (13) connected to the high-temperature regenerator (2) is installed in the second cylinder, a turbine (9) is installed at the end of the rotating shaft (4) located in the second cylinder, a first circulation structure (18) for gas circulation is provided in the first cylinder, a second circulation structure (17) for gas circulation is provided in the second cylinder, and a cooler (12) is installed in the first cylinder.

2. A compact supercritical carbon dioxide recompression cycle power plant according to claim 1, characterized in that: The first cylinder body comprises a first inner shell (3) and a first outer shell (8) both ends of which are open, wherein one end of the first outer shell (8) is closed and the other end has an opening; the first inner shell (3) is sleeved on the outer wall of the high-temperature regenerator (2); the first outer shell (8) is sleeved on the outer wall of the first inner shell (3); the first circulation structure (18) is installed between the first inner shell (3) and the first outer shell (8); a guide channel is opened on the side of the first inner shell (3) close to the recompressor (10), and the first circulation structure (18) is connected to the guide channel.

3. A compact supercritical carbon dioxide recompression cycle power plant according to claim 2, characterized in that: A main compressor stator blade structure (30) matching the main compressor (11) is installed in the first inner shell (3), and a re-compressor stator blade structure (31) matching the re-compressor (10) is installed in the first inner shell (3). A conical guide structure (19) for guiding gas flow is provided between the main compressor stator blade structure (30) and the re-compressor stator blade structure (31), and a mounting opening adapted to the rotating shaft (4) is provided on the guide structure (19).

4. A compact supercritical carbon dioxide recompression cycle power plant according to claim 2, characterized in that: The second cylinder body includes a second inner shell (16) with both ends open and a second outer shell (1), one end of the second outer shell (1) is closed and the other end has an opening; the second inner shell (16) is sleeved on the outer wall of the high-temperature regenerator (2), the second outer shell (1) is sleeved on the outer wall of the second inner shell (16), the second circulation structure (17) is installed between the second inner shell (16) and the second outer shell (1), and a turbine stator structure (32) matching the turbine (9) is provided on the inner wall of the second inner shell (16).

5. A compact supercritical carbon dioxide recompression cycle power plant according to claim 2 or 4, characterized in that: A plurality of semi-annular hollow sandwich structures are sequentially arranged in the first inner shell (3) or the second inner shell (16) along its axial direction.

6. A compact supercritical carbon dioxide recompression cycle power plant according to claim 5, characterized in that: The cooler (12) is divided into two groups. The two coolers (12) are spliced ​​together and arranged around the outside of the main compressor (11); the cooler (12) includes a first bushing and a second bushing, the first bushing is installed in the second bushing, and a plurality of cooling structures are installed between the first bushing and the second bushing. The inner cavity of the cooling structure is provided with a zigzag heat exchange flow channel (20), and the outer wall of the second bushing is provided with two water tanks (14) respectively connected to the inner cavity of the cooling structure, one of the water tanks (14) is provided with two cooling water inlet pipes (5) on the outer wall, and the outer upper blade of the other water tank (14) is provided with two cooling water outlet pipes (6), and a zigzag gas channel (22) is provided between any two adjacent cooling structures.

7. The compact supercritical carbon dioxide recompression cycle power plant according to claim 5, characterized in that: The low-temperature regenerator (15) is arranged on the periphery of the recompressor (10), the small-diameter end of the low-temperature regenerator (15) faces the high-temperature regenerator (2), a low-temperature gas inlet and outlet (25) is provided on the large-diameter end face of the low-temperature regenerator (15), and a first low-temperature gas flow channel (33) is provided in a zigzag arrangement and connected to the low-temperature gas inlet and outlet (25) on the outer wall of the low-temperature regenerator (15); a high-temperature gas inlet and outlet (34) is provided on the large-diameter inner wall of the low-temperature regenerator (15), and a first high-temperature gas flow channel (27) is provided in a zigzag arrangement and connected to the high-temperature gas inlet and outlet (34) on the outer wall of the low-temperature regenerator (15), and the first high-temperature gas flow channel (27) is located between any two adjacent first low-temperature gas flow channels (33).

8. The compact supercritical carbon dioxide recompression cycle power plant according to claim 5, characterized in that: The high-temperature regenerator (2) is divided into two groups, and the two groups of high-temperature regenerators (2) are connected to each other to form a circular ring shape; the high-temperature regenerator (2) includes a plurality of high-temperature gas circulation structures arranged in a surrounding manner, and a second low-temperature gas flow channel (23) arranged in a zigzag manner is provided between any two adjacent high-temperature gas circulation structures, and a second high-temperature gas flow channel (26) arranged in a zigzag manner is provided in the inner cavity of the high-temperature gas circulation structure, and two inlet and outlet channels (24) are provided on the outer wall of the high-temperature gas circulation structure, and the two inlet and outlet channels (24) are both connected to the second high-temperature gas flow channel (26).

9. The compact supercritical carbon dioxide recompression cycle power plant according to claim 5, characterized in that: The heat source (13) comprises two groups of reactor pressure vessels spliced ​​together, and the two groups of reactor pressure vessels are spliced ​​together to form a ring structure. A chamber is provided on the outer wall of the reactor pressure vessel, and an air inlet (28) communicating with the chamber is provided at one end of the reactor pressure vessel, and an air outlet (29) communicating with the chamber is provided at the other end of the reactor pressure vessel. The chamber is filled with spherical fuel elements, and two groups of control ball guide tubes (7) are installed in the chamber, and both ends of the control ball guide tube (7) pass through the outer wall of the reactor pressure vessel and extend outward.

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