Low-power S-CO2 turbine power generation all-in-one machine and using method thereof
By setting up an expansion stage in the reverse axial force direction in the low-power S-CO2 turbine generator and using axial thrust bearing, the small-power S-CO2 turbine between the axial force balance and the output performance is solved. The contradiction of the system achieves excellent output performance and compact structural design, and promotes the application of equipment.
Patent Information
- Application Number
- CN202411441403.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2024-12-10
AI Technical Summary
There is a contradiction between the axial force balance and output performance, resulting in limited application in waste heat recovery and small power equipment generation.
A low-power S-CO2 turbine generator is designed. By setting two expansion stages on the high-voltage side shaft and the low-voltage side shaft, and using the design of the reverse axial force direction, combining the axial direction on the low-voltage side shaft. Thrust bearings achieve axial force balance while avoiding the use of split expansion schemes, maintaining a high blade height to reduce expansion losses.
It achieves excellent output performance under balanced axial force, and the integrated design makes the overall structure compact and the volume smaller, enhancing the potential for promotion and application of the equipment.
Smart Images
Figure CN119102789A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of small power generation equipment, and in particular to a small-power S-CO2 turbine integrated power generation machine and a method of using the same. Background Art
[0002] At present, the energy structure of various countries is still dominated by non-renewable energy such as coal and oil in the short term, and a large amount of greenhouse gases such as CO2 will inevitably be produced in the process of energy conversion, thereby exacerbating the process of global warming. The S-CO2 cycle uses CO2 as the working fluid, which can achieve the disguised fixation of CO2 to reduce carbon emissions. At the same time, by utilizing the characteristics of S-CO2's high constant pressure specific heat and energy density, it can improve the cycle efficiency and reduce the size of components. The characteristics of CO2 such as low cost, non-toxic and harmless, and non-corrosive also make it a more ideal circulating working fluid. Therefore, the S-CO2 cycle technology has broad research prospects in many fields such as thermal power, nuclear power, solar energy, and waste heat recovery.
[0003] Among them, the S-CO2 turbine, as the core component in the S-CO2 cycle, directly determines the performance of the power cycle. However, due to the characteristics of high pressure of CO2, the S-CO2 turbine has the problem of large axial force and difficulty in balancing. At present, in high-power S-CO2 turbines, split-flow symmetrical expansion similar to steam turbines can be adopted, or balancing holes can be opened on the impeller to reduce the axial force and achieve safe operation of the turbine; but in low-power S-CO2 turbines, due to the small flow rate, if the split-flow symmetrical expansion method is still adopted, the height of the turbine blades will be too low, which will further lead to a significant increase in expansion losses, which is not conducive to improving the efficiency of the turbine, and the opening of balancing holes will also affect the already low output performance of the low-power turbine.
[0004] Therefore, the contradiction between the axial force balance and output performance of small-power S-CO2 and its mixed working fluid turbines is a key technical issue that restricts their widespread application in waste heat recovery and power generation of small power equipment. Summary of the invention
[0005] The present application provides a small-power S-CO2 turbine integrated power generation machine and a method of use, so as to at least solve the problem of the contradiction between the axial force balance and the output performance of the axial flow turbine of the small-power S-CO2 and its mixed working fluid in the related art.
[0006] In a first aspect, the present application provides a small-power S-CO2 turbine generator, comprising a body, wherein a main chamber is provided inside the body and has a working fluid inlet connected to the main chamber, and a working fluid outlet connected to the main chamber, and further comprising:
[0007] A generator, which is arranged in the main chamber and has at least a stator, a rotor, a high-pressure side shaft and a low-pressure side shaft, wherein the rotor is movably arranged inside the stator, and the high-pressure side shaft and the low-pressure side shaft are respectively fixed to two ends of the rotor;
[0008] There are two expansion stages, which are respectively arranged on the high-pressure side shaft and the low-pressure side shaft. The expansion stage arranged on the high-pressure side shaft has a high-pressure expansion stage inlet and a high-pressure expansion stage outlet, and the expansion stage arranged on the low-pressure side shaft has a low-pressure expansion stage inlet and a low-pressure expansion stage outlet. The high-pressure expansion stage outlet is connected to the low-pressure expansion stage inlet through a high-low pressure stage connecting pipe;
[0009] The high-pressure expansion stage outlet and the low-pressure expansion stage outlet are respectively arranged on one side close to the rotor component, the high-pressure expansion stage inlet is connected to the working medium inlet, and the low-pressure expansion stage outlet is connected to the working medium outlet.
[0010] Optionally, the expansion stage further comprises:
[0011] a stationary blade cascade fixed at the inlet of the high-pressure expansion stage or the inlet of the low-pressure expansion stage;
[0012] The moving blade grid is fixedly arranged on the high-pressure side shaft or the low-pressure side shaft and is located near the high-pressure expansion stage outlet or the low-pressure expansion stage outlet.
[0013] Optionally, radial support bearings are mounted on both the high-pressure side shaft and the low-pressure side shaft, and outer ends of the radial support bearings are interference fit with the inner wall of the main chamber.
[0014] Optionally, the low-pressure side shaft is also equipped with an axial thrust bearing for offsetting the unilateral axial force directed from the high-pressure stage to the low-pressure stage to avoid displacement of the high-pressure side shaft and the low-pressure side shaft.
[0015] Optionally, seals are provided on the expansion stage, the high-pressure side shaft and the low-pressure side shaft.
[0016] Optionally, the sealing element is a comb teeth sealing ring.
[0017] Optionally, an air cooling passage is provided on the machine body, which is connected to the main chamber corresponding to the positions of the high-pressure side shaft and the low-pressure side shaft to cool the expansion stage, the radial support bearing and the axial thrust bearing.
[0018] Optionally, the cooling medium in the air-cooling passage is low-temperature CO2.
[0019] Optionally, the machine body is further provided with a liquid cooling passage, which is opened at a position in the machine body corresponding to the stator component and surrounds the main chamber in a threaded shape.
[0020] In a second aspect, the present application provides a method for using a small-power S-CO2 turbine integrated power generator, the method being applied to the small-power S-CO2 turbine integrated power generator provided in the first aspect, comprising:
[0021] The S-CO2 working fluid is input into the machine body from the working fluid inlet, and is expanded into the first state working fluid for the first time through the expansion stage of the high-pressure side shaft. The first state working fluid is reversely input into the expansion stage of the low-pressure side shaft through the high- and low-pressure stage connecting pipe, and is expanded into the second state working fluid for the second time, and is output from the machine body through the working fluid outlet;
[0022] The energy from the expansion of the first-state working fluid drives the high-pressure side shaft to rotate, and the energy from the expansion of the second-state working fluid drives the low-pressure side shaft to rotate in the same direction as the high-pressure side shaft, so as to synchronously drive the rotor component to rotate coaxially around the stator component, and output electrical energy based on the principle of electromagnetic induction.
[0023] Compared with the related art, the low-power S-CO2 turbine generator integrated machine and its use method provided by this application have at least the following technical effects:
[0024] By arranging the two expansion stages symmetrically on the high-pressure side shaft and the low-pressure side shaft of the generator, the axial forces generated by each stage are in opposite directions to offset most of the axial forces. Finally, with the help of the axial thrust bearing on the low-pressure side shaft, the axial force of the shaft system can be perfectly balanced to avoid safety problems. At the same time, since the existing split-flow expansion scheme is not adopted, the blade height of each stage can also be maintained at a relatively high acceptable level, reducing the excessive expansion loss caused by the smaller blade height, and thus ensuring excellent output performance under the premise of balancing the axial force; and no coupling is used between the generator and the expansion stage, completing the integrated design of the S-CO2 turbine and the generator, making the overall structure more compact and the volume further reduced, which is conducive to the promotion and application of the equipment.
[0025] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:
[0027] Figure 1 It is a three-dimensional diagram of a small-power S-CO2 turbine integrated power generator according to an exemplary embodiment.
[0028] Figure 2 It is a front view of a small-power S-CO2 turbine power generation integrated machine according to an exemplary embodiment.
[0029] Figure 3 It is a cross-sectional view of a small-power S-CO2 turbine integrated power generation machine according to an exemplary embodiment.
[0030] Figure 4 is based on Figure 3 A magnified schematic diagram of the structure in Figure 1.
[0031] Figure 5 is based on Figure 3 A magnified schematic diagram of structure B.
[0032] In the figure: a machine body 10; a machine body base 101; a working fluid inlet 102; a working fluid outlet 103;
[0033] Expansion stage 20; high pressure expansion stage inlet 201; high pressure expansion stage outlet 202; high and low pressure stage connecting pipe 203; low pressure expansion stage inlet 204; low pressure expansion stage outlet 205;
[0034] Generator 30; rotor component 301; stator component 302; high-pressure side shaft 303; low-pressure side shaft 304;
[0035] Stationary blade cascade 40; moving blade cascade 50; radial support bearing 60; axial thrust bearing 601; sealing element 70;
[0036] Air cooling passage 80; liquid cooling passage 90. DETAILED DESCRIPTION
[0037] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.
[0038] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.
[0039] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.
[0040] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.
[0041] In the relevant technology, the S-CO2 turbine, as the core component in the S-CO2 cycle process, directly determines the performance of the power cycle. However, due to the characteristics of high pressure of CO2, the S-CO2 turbine has the problem of large axial force and difficulty in balancing. At present, in high-power S-CO2 turbines, a split-flow symmetrical expansion similar to that of a steam turbine can be adopted, or a balancing hole can be opened on the impeller to reduce the axial force and achieve safe operation of the turbine; but in low-power S-CO2 turbines, due to the small flow rate, if the split-flow symmetrical expansion method is still adopted, the height of the turbine blades will be too low, which will further lead to a significant increase in expansion losses, which is not conducive to improving the efficiency of the turbine, and the opening of balancing holes will also affect the already low output performance of the low-power turbine. The contradiction between the axial force balance and output performance of low-power S-CO2 and its mixed working fluid turbine is a key technical problem that restricts its widespread application in waste heat recovery and power generation of small power equipment.
[0042] Based on the above situation, an embodiment of the present invention provides a small-power S-CO2 turbine integrated power generation machine and a method of using the same, which will be described in detail below in conjunction with specific embodiments and drawings.
[0043] Example 1
[0044] The embodiment of the present invention provides a small-power S-CO2 turbine integrated power generation machine. Figure 1 It is a three-dimensional diagram of a small-power S-CO2 turbine integrated power generator according to an exemplary embodiment. Figure 2 It is a front view of a small-power S-CO2 turbine power generation integrated machine according to an exemplary embodiment. Figure 3 FIG. 1 is a cross-sectional view of a small-power S-CO2 turbine generator according to an exemplary embodiment. Figure 1-Figure 3 As shown, the turbine generator integrated machine includes a machine body 10 and a machine body base 101 arranged at the lower part of the machine body 10. The machine body 10 has a main chamber inside and has a working medium inlet 102 connected to the main chamber and a working medium outlet 103 connected to the main chamber. It also includes:
[0045] The generator 30 is arranged in the main chamber and has at least a rotor part 301, a stator part 302, a high-pressure side shaft 303 and a low-pressure side shaft 304. The rotor part 301 is movably arranged inside the stator part 302, and the high-pressure side shaft 303 and the low-pressure side shaft 304 are respectively fixed at both ends of the stator part 302; in this embodiment, the generator 30 is a high-speed permanent magnet synchronous generator, which should be able to cover the high speed range of the turbine (10000rpm~50000rpm) and can maintain a high power generation efficiency within this speed range.
[0046] There are two expansion stages 20, which are respectively arranged on the high-pressure side shaft 303 and the low-pressure side shaft 304. The expansion stage 20 arranged on the high-pressure side shaft 303 has a high-pressure expansion stage inlet 201 and a high-pressure expansion stage outlet 202, and the expansion stage 20 arranged on the low-pressure side shaft 304 has a low-pressure expansion stage inlet 204 and a low-pressure expansion stage outlet 205. The high-pressure expansion stage outlet 202 is connected to the low-pressure expansion stage inlet 204 through a high-low pressure stage connecting pipe 203; further, the expansion stage 20 also includes: a stationary blade cascade 40, which is fixed at the high-pressure expansion stage inlet 201 or the low-pressure expansion stage inlet 204; a moving blade cascade 50, which is fixedly arranged on the high-pressure side shaft 303 or the low-pressure side shaft 304, and is located near the high-pressure expansion stage outlet 202 or the low-pressure expansion stage outlet 205. The expansion stage 20 generally has a row of stationary blades 40 and a row of moving blades 50, which is the basic unit of turbine expansion, wherein the stationary blades 40 mainly complete the conversion of the internal energy of the working fluid into kinetic energy, while the moving blades 50 mainly complete the conversion of the kinetic energy of the working fluid into the rotational mechanical energy of the shaft system.
[0047] The high pressure expansion stage outlet 202 and the low pressure expansion stage outlet 205 are respectively arranged on one side close to the stator component 302 , the high pressure expansion stage inlet 201 is connected to the working medium inlet 102 , and the low pressure expansion stage outlet 205 is connected to the working medium outlet 103 .
[0048] Figure 4 is based on Figure 3 A magnified schematic diagram of the structure in Figure 1. Figure 5 is based on Figure 3 See attached for an enlarged schematic diagram of structure B. Figure 3-Figure 5 In this embodiment, both the high-pressure side shaft 303 and the low-pressure side shaft 304 are equipped with radial support bearings 60, and the outer ends of the radial support bearings 60 are interference fit with the inner wall of the main chamber; wherein, the low-pressure side shaft 304 is also equipped with an axial thrust bearing 601 for offsetting the unilateral axial force from the high-pressure stage to the low-pressure stage to avoid displacement of the high-pressure side shaft 303 and the low-pressure side shaft 304.
[0049] In the technical solution of the above embodiment, since the working fluid flow rate of the small-power S-CO2 turbine integrated machine itself is small, it is not suitable to use the split symmetrical expansion method of the low-pressure cylinder of the power plant to balance the axial force. Therefore, it is still necessary to reasonably distribute the total enthalpy reduction to multiple expansion stages to avoid the supersonic flow and large shock wave losses that may occur in the case of a single expansion stage. The shock wave loss refers to the expansion loss caused by the severe shock wave boundary layer interference caused by the high Mach number flow during the expansion process, which has a great influence on the turbine expansion performance.
[0050] In this embodiment, the specific working process is as follows: the S-CO2 working medium is input into the body 10 from the working medium inlet 102, and the S-CO2 working medium is expanded into the first state working medium for the first time through the expansion stage 20 of the high-pressure side shaft 303, and the first state working medium is reversely input into the expansion stage 20 of the low-pressure side shaft 304 through the high-low pressure stage connecting pipe 203, and is expanded into the second state working medium for the second time, and is output from the body 10 through the working medium outlet 103;
[0051] In the above process, the energy of the expansion of the first-state working fluid drives the high-pressure side shaft 303 to rotate, and the energy of the expansion of the second-state working fluid drives the low-pressure side shaft 304 to rotate in the same direction as the high-pressure side shaft 303. Since the mainstream directions of the fluids on the high-pressure side shaft 303 and the low-pressure side shaft 304 are opposite, the axial forces generated by the expansion stages 20 on both sides are also opposite, thereby balancing most of the axial forces of the turbine itself. At the same time, since the pressure drop on the high-pressure side is large, the resultant axial force is directed from the high-pressure stage to the low-pressure stage. Therefore, it is necessary to install an axial thrust bearing 601 on the low-pressure side to withstand a small part of the axial force, thereby offsetting the unilateral axial force from the high-pressure stage to the low-pressure stage, avoiding the movement of the shaft system, and synchronously driving the stator component 302 to rotate coaxially around the rotor component 301; combined with the overall structure of the coaxial arrangement of the turbine and the generator, the generator speed is the same as the expansion stage speed, the generator can operate at a high speed for a long time and can maintain a high power generation efficiency within a wide speed range.
[0052] In this embodiment, by arranging two expansion stages 20 symmetrically on the high-pressure side shaft 303 and the low-pressure side shaft 304 of the generator 30, the axial forces generated by each stage are in opposite directions to offset most of the axial forces. Finally, with the help of the axial thrust bearing 601 on the low-pressure side shaft 304, the axial force of the shaft system can be perfectly balanced to avoid safety problems. At the same time, since the existing split-flow expansion scheme is not adopted, the blade height of each stage can also be maintained at a relatively high acceptable level, reducing the excessive expansion loss caused by the smaller blade height, and thus ensuring excellent output performance under the premise of balancing the axial force; and no coupling is used between the generator 30 and the expansion stage, completing the integrated design of the turbine and the generator, making the overall structure more compact and the volume further reduced, which is conducive to the promotion and application of the equipment.
[0053] In this embodiment, the expansion stage 20, the high pressure side shaft 303 and the low pressure side shaft 304 are all provided with a seal 70, wherein, continue to refer to the attached Figure 4-Figure 5 In this embodiment, the seal 70 is a comb seal ring, which includes comb teeth for sealing the blade tip clearance at the top of the moving blade grid 50, and also includes sealing comb teeth at the axial end positions of the high-pressure side shaft 303 and the low-pressure side shaft 304.
[0054] In this embodiment, an air-cooling passage 80 is provided on the machine body 10, which is connected to the main chamber corresponding to the high-pressure side shaft 303 and the low-pressure side shaft 304 to cool the expansion stage 20, the radial support bearing 60 and the axial thrust bearing 601; wherein, the cooling medium in the air-cooling passage 80 is low-temperature CO2, and the cooling fan returns the low-temperature CO2 that has been expanded and reheated and cooled, thereby avoiding the introduction of other cooling media and ensuring the singleness of the flowing media.
[0055] Optionally, the machine body 10 is further provided with a liquid cooling passage 90 , which is opened at a position corresponding to the rotor component 301 in the machine body 10 and surrounds the main chamber in a threaded shape, so as to be mainly used for cooling the stator component 302 of the generator 30 .
[0056] In summary, the small-power S-CO2 turbine generator integrated machine provided by the embodiment of the present invention arranges two expansion stages 20 symmetrically on the high-pressure side shaft 303 and the low-pressure side shaft 304 of the generator 30, so that the axial forces generated by each stage are in opposite directions to offset most of the axial forces, and finally, with the assistance of the axial thrust bearing 601 on the low-pressure side shaft 304, the axial force of the shaft system can be perfectly balanced to avoid safety problems. At the same time, since the existing diversion expansion scheme is not adopted, the blade height of each stage can also be maintained at a relatively high acceptable level, reducing the excessive expansion loss caused by the smaller blade height, and thus ensuring excellent output performance under the premise of balancing the axial force; and no coupling is used between the generator 30 and the expansion stage, completing the integrated design of the turbine and the generator, making the overall structure more compact and the volume further reduced, which is conducive to the promotion and application of the equipment.
[0057] Example 2
[0058] Embodiment 2 of the present invention provides a method for using a small-power S-CO2 turbine integrated power generator, which is applied to the small-power S-CO2 turbine integrated power generator provided in the first aspect above, comprising:
[0059] The S-CO2 working medium is input into the body 10 from the working medium inlet 102, and is expanded into the first state working medium through the expansion stage 20 of the high-pressure side shaft 303 for the first time. The first state working medium is reversely input into the expansion stage 20 of the low-pressure side shaft 304 through the high-low pressure stage connecting pipe 203, and is expanded into the second state working medium for the second time, and is output from the body 10 through the working medium outlet 103;
[0060] The energy of the first-state working fluid expansion drives the high-pressure side shaft 303 to rotate, and the energy of the second-state working fluid expansion drives the low-pressure side shaft 304 to rotate in the same direction as the high-pressure side shaft 303, so as to synchronously drive the stator component 302 to rotate coaxially around the rotor component 301, and output electrical energy based on the principle of electromagnetic induction.
[0061] For other structures not described, refer to Example 1.
[0062] In summary, the small-power S-CO2 turbine generator integrated machine and its use method provided by the embodiment of the present invention arrange the two expansion stages 20 symmetrically on the high-pressure side shaft 303 and the low-pressure side shaft 304 of the generator 30 so that the axial forces generated by each stage are in opposite directions to offset most of the axial forces. Finally, with the assistance of the axial thrust bearing 601 on the low-pressure side shaft 304, the axial force of the shaft system can be perfectly balanced to avoid safety problems. At the same time, since the existing diversion expansion scheme is not adopted, the blade height of each stage can also be maintained at a relatively high acceptable level, reducing the excessive expansion loss caused by the smaller blade height, and thus ensuring excellent output performance under the premise of balancing the axial force. Moreover, no coupling is used between the generator 30 and the expansion stage, completing the integrated design of the turbine and the generator, making the overall structure more compact and the volume further reduced, which is conducive to the promotion and application of the equipment.
[0063] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0064] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.
Claims
1. A small-power S-CO2 turbine generator, comprising a body, wherein a main chamber is provided inside the body and a working fluid inlet connected to the main chamber and a working fluid outlet connected to the main chamber are provided, characterized in that: Also included are: A generator, which is arranged in the main chamber and has at least a stator, a rotor, a high-pressure side shaft and a low-pressure side shaft, wherein the rotor is movably arranged inside the stator, and the high-pressure side shaft and the low-pressure side shaft are respectively fixed to two ends of the rotor; There are two expansion stages, which are respectively arranged on the high-pressure side shaft and the low-pressure side shaft. The expansion stage arranged on the high-pressure side shaft has a high-pressure expansion stage inlet and a high-pressure expansion stage outlet, and the expansion stage arranged on the low-pressure side shaft has a low-pressure expansion stage inlet and a low-pressure expansion stage outlet. The high-pressure expansion stage outlet is connected to the low-pressure expansion stage inlet through a high-low pressure stage connecting pipe; The high-pressure expansion stage outlet and the low-pressure expansion stage outlet are respectively arranged on one side close to the rotor component, the high-pressure expansion stage inlet is connected to the working medium inlet, and the low-pressure expansion stage outlet is connected to the working medium outlet.
2. The integrated generator according to claim 1, characterized in that: The expansion stage also includes: a stationary blade cascade fixed at the inlet of the high-pressure expansion stage or the inlet of the low-pressure expansion stage; The moving blade grid is fixedly arranged on the high-pressure side shaft or the low-pressure side shaft and is located near the high-pressure expansion stage outlet or the low-pressure expansion stage outlet.
3. The integrated generator according to claim 1, characterized in that: The high-pressure side shaft and the low-pressure side shaft are both equipped with radial support bearings, and the outer ends of the radial support bearings are interference-fitted with the inner wall of the main chamber.
4. The integrated generator according to claim 3, characterized in that: The low-pressure side shaft is also equipped with an axial thrust bearing for offsetting the unilateral axial force directed from the high-pressure stage to the low-pressure stage to avoid displacement of the high-pressure side shaft and the low-pressure side shaft.
5. The integrated generator according to claim 1, characterized in that: The expansion stage, the high-pressure side shaft and the low-pressure side shaft are all provided with seals.
6. The integrated generator according to claim 5, characterized in that: The sealing element is a comb teeth sealing ring.
7. The integrated generator according to claim 4, characterized in that: The machine body is provided with an air cooling passage which is connected to the main chamber corresponding to the positions of the high-pressure side shaft and the low-pressure side shaft to cool the expansion stage, the radial support bearing and the axial thrust bearing.
8. The integrated power generator according to claim 1, characterized in that: The cooling medium in the air cooling passage is low-temperature CO2.
9. The integrated power generator according to claim 1, characterized in that: The machine body is also provided with a liquid cooling passage, which is opened at a position in the machine body corresponding to the stator component and surrounds the main chamber in a threaded shape.
10. A method for using a small-power S-CO2 turbine generator, characterized in that: The method is applied to the small-power S-CO2 turbine power generation integrated machine described in claims 1 to 9, comprising: The S-CO2 working fluid is input into the machine body from the working fluid inlet, and is expanded into the first state working fluid for the first time through the expansion stage of the high-pressure side shaft. The first state working fluid is reversely input into the expansion stage of the low-pressure side shaft through the high- and low-pressure stage connecting pipe, and is expanded into the second state working fluid for the second time, and is output from the machine body through the working fluid outlet; The energy from the expansion of the first-state working fluid drives the high-pressure side shaft to rotate, and the energy from the expansion of the second-state working fluid drives the low-pressure side shaft to rotate in the same direction as the high-pressure side shaft, so as to synchronously drive the rotor component to rotate coaxially around the stator component, and output electrical energy based on the principle of electromagnetic induction.