Quasi-isothermal expansion axial flow turbine and quasi-isothermal expansion nuclear power generation system

Abstract

The invention discloses a quasi-isothermal expansion axial flow turbine and a quasi-isothermal expansion nuclear energy power generation system. The axial flow turbine comprises a shell, a rotating shaft and a medium inlet and outlet assembly. A plurality of stationary blades are arranged on the inner wall of the shell; a plurality of passages are formed in the side wall of the stationary blade in a penetrating mode, first channels are formed between the passages and the inner ring of the stationary blade, second channels are formed between the passages and the outer ring of the stationary blade, and third channels are formed between every two adjacent passages. The rotating shaft is rotationally connected into the shell; a plurality of movable blades are mounted on the rotating shaft, and the movable blades and the fixed blades are alternately arranged; the medium inlet and outlet assembly is installed on the shell and communicates with the second channel. The nuclear power generation system comprises a quasi-isothermal expansion axial flow turbine, a compressor, a cooler, a heat regenerator, a heat exchanger, a reactor and a power generator. The working medium is heated through the stationary blades of the axial flow turbine, equivalently, a reheater is integrated into the turbine, quasi-isothermal expansion of the working medium is achieved in the turbine, and the power capability and efficiency of circulation are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and particularly to a quasi-isothermal expansion axial flow turbine and a quasi-isothermal expansion nuclear power generation system. Background Art

[0002] As a new generation of green, low-carbon and efficient power generation technology, the currently used reactor types for nuclear power generation mainly include the fourth-generation nuclear reactors, space power reactors, small modular reactors, etc. Focusing on the fourth-generation nuclear reactors, their temperature can reach 500 to 800 °C, and the conventional steam working fluids cannot meet the requirements in this temperature range. Research shows that the supercritical carbon dioxide (SCO 2 ) Brayton cycle has good application prospects in the field of nuclear power. Comparing it with the other two common working fluids, He and water vapor, within the above temperature range, using SCO 2 cycle can increase the efficiency by more than 10%. In addition, due to the characteristics of SCO 2 such as high density, low viscosity and good heat transfer performance, the key components such as compressors and turbines are smaller in size, and the entire cycle system is compact with a small floor area. The above characteristics make it particularly useful in nuclear power systems with limited space, such as ship propulsion and long-range space exploration.

[0003] In order to improve the cycle thermal efficiency, many measures such as regeneration, reheating, splitting and their combinations have been proposed to improve the Brayton cycle to increase its cycle efficiency. Reheating means adding a reheater in the cycle to heat the low-pressure working fluid that has done work to a certain temperature and then sending it into the turbine to do work again. As Figure 1 is the regenerative recompression SCO 2 nuclear power generation system in the prior art, Figure 2 is the temperature-entropy diagram of the cycle of this system. It can be seen in Figure 1 that after the working fluid does work in the turbine, it is extracted and enters the reheater for heating, and then enters the turbine to do work again, which is the reheating process. Figure 2 It can be seen in Figure 2 that after this process, the net work output of the entire cycle has a significant increase compared with the initial Brayton cycle ( Figure 2 the dotted line part). The advantage of reheating is that it can increase the output work of the cycle. With the assistance of a regenerative device, the cycle efficiency can be effectively improved. Theoretically, the more the number of reheating stages, the closer the expansion process of the working fluid is to isothermal expansion, and the greater the net work output of the cycle. However, the number of reheating stages is limited by conditions such as cost and economic benefits, and extracting the working fluid from the turbine and entering the reheater for heat exchange will also cause a large pressure drop loss. Currently, two-stage reheating is generally adopted. More importantly, the reheating device and related pipelines will significantly increase the volume and weight of the system, which will weaken SCO 2The advantage of a compact circulatory system with a small footprint becomes a significant drawback in applications sensitive to system volume and weight, such as ship propulsion, aerospace, etc. Generally speaking, although the above traditional reheating measures can increase cycle work output, they are still limited.

[0004] Therefore, a quasi-isothermal expansion axial flow turbine and a quasi-isothermal expansion nuclear power generation system are proposed. Summary of the Invention

[0005] The object of the present invention is to provide a quasi-isothermal expansion axial flow turbine and a quasi-isothermal expansion nuclear power generation system, aiming to solve or improve at least one of the above technical problems.

[0006] To achieve the above object, the present invention provides the following solution: The present invention provides a quasi-isothermal expansion axial flow turbine, comprising:

[0007] A housing, on the inner wall of which there are several stationary blades; the several stationary blades are arranged at intervals along the inner wall of the housing; the transverse cross-sectional shape of the stationary blade is annular, and several through passages are formed through the side wall of the stationary blade, and the several through passages are arranged circumferentially along the axis of the stationary blade. A first channel is provided between the through passage and the inner ring of the stationary blade, and a second channel is provided between the through passage and the outer ring of the stationary blade. A third channel is provided between two adjacent through passages, and the first channel and the second channel are connected through several third channels; the through passage is used for the circulation of SCO 2 working medium;

[0008] A rotating shaft, which is rotatably connected in the housing and penetrates through the inner ring of the stationary blade; several moving blades are installed on the rotating shaft, and the several moving blades are arranged at intervals along the axis of the rotating shaft, and the several moving blades and the several stationary blades are arranged alternately;

[0009] A medium inlet and outlet assembly, which is installed on the housing and is connected to the second channel for introducing a heating medium into the second channel.

[0010] According to the quasi-isothermal expansion axial flow turbine provided by the present invention, the medium inlet and outlet assembly includes an outlet and an inlet, both of which are installed on the housing. The outlet is fixedly connected to the top of the outer ring of the stationary blade, the inlet is fixedly connected to the bottom of the outer ring of the stationary blade, and both the outlet and the inlet are connected to the second channel.

[0011] According to the quasi-isothermal expansion axial flow turbine provided by the present invention, the heating medium includes but is not limited to liquid sodium or water vapor.

[0012] According to the quasi-isothermal expansion axial flow turbine provided by the present invention, the several through passages are arranged circumferentially at equal intervals along the axis of the stationary blade.

[0013] The present invention also provides a quasi-isothermal expansion nuclear power generation system, which includes the quasi-isothermal expansion axial flow turbine described above, and further includes a compressor, a cooler, a regenerator, a heat exchanger, a reactor and a generator;

[0014] The compressor is connected to the regenerator through a second pipeline, the regenerator is connected to the heat exchanger through a third pipeline, the heat exchanger is connected to the passage of the quasi-isothermal expansion axial flow turbine through a fourth pipeline, the passage of the quasi-isothermal expansion axial flow turbine is connected to the regenerator through a fifth pipeline, the regenerator is connected to the cooler through a sixth pipeline, and the cooler is connected to the compressor through a first pipeline; the first pipeline, the second pipeline, the third pipeline, the fourth pipeline, the fifth pipeline and the sixth pipeline are all used for transporting SCO 2 working medium;

[0015] The reactor is connected to the heat exchanger through a seventh pipeline, the medium inlet and outlet assembly of the quasi-isothermal expansion axial flow turbine is connected to the reactor through an eighth pipeline, the heat exchanger is connected to the reactor through a ninth pipeline, and the reactor is connected to the medium inlet and outlet assembly of the quasi-isothermal expansion axial flow turbine through a tenth pipeline; the seventh pipeline, the eighth pipeline, the ninth pipeline and the tenth pipeline are all used for transporting heating medium; the rotating shaft of the quasi-isothermal expansion axial flow turbine is connected to the generator.

[0016] The present invention discloses the following technical effects:

[0017] The present invention uses the stator blades of the axial flow turbine to heat the working medium, which is equivalent to integrating the reheater into the turbine, enabling the working medium to achieve quasi-isothermal expansion in the turbine, and improving the work capacity and efficiency of the cycle; by improving the axial flow turbine, the SCO 2 working medium expands and absorbs heat inside the casing of the turbine, realizing a process similar to isothermal expansion, and can further improve the system efficiency without significantly increasing other system devices;

[0018] The stator blades of the present invention are of a hollow structure, and the heating medium flows through and exchanges heat with the first channel, the second channel and the third channel inside it, heating the SCO 2 working medium after the previous-stage rotor blade does work, and is discharged after several processes of the above-mentioned work-heating. The total process in the turbine is approximately a quasi-isothermal expansion process, and the work capacity and efficiency of the cycle are effectively improved;

[0019] Compared with traditional reheating, which generally has at most two stages due to limitations such as cost and mechanical efficiency of the device, the combination of several moving blades and stationary blades in the axial flow turbine of the present invention is equivalent to the function of multi-stage reheating, effectively reducing the volume of the system while further improving the efficiency. This is a significant advantage in some application scenarios with strict requirements for the floor area and volume of the system, enabling the improvement of the cycle efficiency within the same cycle temperature range; or reducing the maximum temperature of the cycle at the same efficiency, thereby reducing the heat resistance requirements for the device materials.

[0020] Due to the low dynamic viscosity of supercritical fluids and the very thin boundary layer, the heat transfer per unit area is greatly increased. Therefore, the effect of reheating using the stationary blade surface is more obvious. The present invention is particularly suitable for supercritical CO 2 Brayton cycle and other supercritical turbine power generation technologies. Brief Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 For the regenerative recompression SCO in the prior art 2 Nuclear power generation system diagram;

[0023] Figure 2 For the regenerative recompression SCO in the prior art 2 Nuclear power generation cycle temperature-entropy diagram;

[0024] Figure 3 Schematic diagram of the quasi-isothermal expansion nuclear power generation system in the present invention;

[0025] Figure 4 Temperature-entropy diagram of the power generation cycle of the quasi-isothermal expansion nuclear power generation system in the present invention;

[0026] Figure 5 Cross-sectional view of the quasi-isothermal expansion axial flow turbine in the present invention;

[0027] Figure 6 For Figure 5 Cross-sectional view of A-A in;

[0028] Figure 7 Structural schematic diagram of Embodiment 2 of the present invention.

[0029] Among them, 1. Rotating shaft; 2. Static blade; 3. Heating medium; 4. Moving blade; 5. Shell; 6. Outlet; 7. Inlet; 8. Passage; 9. Compressor; 10. Cooler; 11. Regenerator; 12. Heat exchanger; 13. Reactor; 14. Generator; 15. Volute; 16. Impeller; 17. End cover. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the drawings and specific implementation manners.

[0032] Embodiment 1

[0033] Referring to Figures 3 - 6 , the present invention provides an approximately isothermal expansion axial turbine, including:

[0034] A shell 5, on the inner wall of the shell 5 are several static blades 2; the shell 5 is in a static state; several static blades 2 are arranged at intervals along the inner wall of the shell 5; the transverse cross-sectional shape of the static blade 2 is annular, and several passages 8 are penetrated through the side wall of the static blade 2, and several passages 8 are arranged circumferentially along the axis of the static blade 2. A first channel is provided between the passage 8 and the inner circle of the static blade 2, a second channel is provided between the passage 8 and the outer circle of the static blade 2, and a third channel is provided between two adjacent passages 8. The first channel and the second channel are communicated through several third channels; the passage 8 is used for flowing SCO 2 working medium;

[0035] A rotating shaft 1, the rotating shaft 1 is rotatably connected in the shell 5, and the rotating shaft 1 penetrates through the inner circle of the static blade 2; several moving blades 4 are installed on the rotating shaft 1, and several moving blades 4 are arranged at intervals along the axis direction of the rotating shaft 1, and several moving blades 4 and several static blades 2 are arranged alternately; Figure 5 Only one group of moving blades 4 and static blades 2 are shown in

[0036] A medium inlet and outlet 6 assembly, the medium inlet and outlet 6 assembly is installed on the shell 5, and the medium inlet and outlet 6 assembly is communicated with the second channel for introducing a heating medium 3 into the second channel;

[0037] With such a setting, when the SCO 2 working medium enters the turbine, it first passes through the moving blade 4, expands and does work on the moving blade 4, and the moving blade 4 drives the rotating shaft 1 to do work externally; then, the SCO2 The working fluid passes through the stator blade 2. Since the interior of the stator blade 2 is filled with the heating medium 3, the SCO 2 working fluid will be reheated when passing through it. Subsequently, it continues to pass through the next pair of moving and stator blades and undergoes a similar process. This cycle repeats until the working fluid is discharged from the turbine;

[0038] This invention utilizes the stator blade 2 of the axial-flow turbine to heat the SCO 2 working fluid, which is equivalent to integrating the reheater into the turbine, enabling the SCO 2 working fluid to achieve quasi-isothermal expansion within the turbine, thereby enhancing the work capacity and efficiency of the cycle. By improving the axial-flow turbine, this invention enables the SCO 2 working fluid to expand and absorb heat simultaneously inside the casing 5 of the turbine, realizing a process similar to isothermal expansion. Without significantly increasing other system devices, the system efficiency can be further improved;

[0039] The stator blade 2 of this invention has a hollow structure. The heating medium 3 flows through and exchanges heat with it in the first channel, second channel, and third channel inside it, heating the SCO 2 working fluid after it has done work in the previous-stage moving blade. After passing through several such work-heating processes, the working fluid is discharged. The overall process in the turbine approximates a quasi-isothermal expansion process, effectively enhancing the work capacity and efficiency of the cycle;

[0040] Compared with traditional reheating, which generally has at most two stages due to limitations such as cost and mechanical efficiency of the device, the combination of several moving blades 4 and stator blades 2 in the axial-flow turbine of this invention is equivalent to the function of multi-stage reheating. It effectively reduces the volume of the system while further improving the efficiency, which is a significant advantage in some application scenarios with strict requirements for system floor area and volume. It can achieve an increase in cycle efficiency within the same cycle temperature range; or at the same efficiency, reduce the maximum cycle temperature, thereby lowering the heat resistance requirements for the device materials;

[0041] Due to the low dynamic viscosity of supercritical fluids and the very thin boundary layer, the heat transfer per unit area is greatly increased. Therefore, the effect of reheating using the surface of the stator blade 2 is more obvious. This invention is particularly suitable for supercritical CO 2 Brayton cycle and other supercritical turbine power generation technologies.

[0042] In a further optimized solution, the medium inlet and outlet 6 assembly includes an outlet 6 and an inlet 7. Both the outlet 6 and the inlet 7 are installed on the casing 5. The outlet 6 is fixedly connected to the top of the outer ring of the stator blade 2, and the inlet 7 is fixedly connected to the bottom of the outer ring of the stator blade 2. Both the outlet 6 and the inlet 7 are in communication with the second channel;

[0043] SCO 2 The working fluid flows through the passage 8, and the heating medium enters from the inlet 7, filling the entire hollow-structured stator blade to heat the SCO 2The working fluid is heated and flows out from outlet 6.

[0044] For a further optimized solution, the heating medium 3 includes but is not limited to liquid sodium or water vapor;

[0045] Taking the existing relatively mature sodium-cooled fast reactor as an example, since the circulating working fluid is SCO 2 , the risk of sodium-water reaction is avoided. The liquid sodium in the reactor loop can be directly pumped into the turbine to act as the heating medium 3. At this time, it is feasible for the heating medium 3 to enter from outlet 6 and discharge from inlet 7 or to discharge from outlet 6 and enter from inlet 7;

[0046] If the heating medium 3 uses water vapor, such as in a pressurized water reactor, it can be introduced from outlet 6. After the steam releases heat and condenses on the inner wall of the stator blade 2, due to the action of gravity, it will naturally converge at the bottom and be discharged from inlet 7;

[0047] Different heating media can adopt different introduction forms and directions.

[0048] For a further optimized solution, a number of passages 8 are arranged at equal intervals circumferentially along the axis of the stator blade 2.

[0049] For a further optimized solution, the flow of the heating medium 3 inside the stator blade 2 is driven by a passive circulation method such as a heat pipe. The self-driving force of the heat pipe comes from the capillary pump effect or the thermosiphon effect.

[0050] This invention only focuses on introducing the process related to the turbine, and other processes of the cycle are simplified; in actual engineering, many measures such as regeneration, reheating, splitting and their combinations are proposed to improve the Brayton cycle. These improvement measures do not conflict with the transformation of the turbine proposed in this invention to achieve quasi-isothermal expansion. That is, a quasi-isothermal expansion turbine can be used in various existing improved Brayton cycle devices to improve the cycle efficiency.

[0051] Generally speaking, the stator blade 2 in the axial-flow turbine not only plays the original role of guiding the air flow, etc., but also plays the role of a reheater.

[0052] This invention also provides a quasi-isothermal expansion nuclear power generation system, including a quasi-isothermal expansion axial-flow turbine, and further including a compressor 9, a cooler 10, a regenerator 11, a heat exchanger 12, a reactor 13 and a generator 14;

[0053] The compressor 9 is connected to the regenerator 11 through the second pipeline, the regenerator 11 is connected to the heat exchanger 12 through the third pipeline, the heat exchanger 12 is connected to the passage 8 of the quasi-isothermal expansion axial flow turbine through the fourth pipeline, the passage 8 of the quasi-isothermal expansion axial flow turbine is connected to the regenerator 11 through the fifth pipeline, the regenerator 11 is connected to the cooler 10 through the sixth pipeline, and the cooler 10 is connected to the compressor 9 through the first pipeline; the first pipeline, the second pipeline, the third pipeline, the fourth pipeline, the fifth pipeline and the sixth pipeline are all used to transport SCO 2 working fluid;

[0054] The reactor 13 is connected to the heat exchanger 12 through the seventh pipeline, the medium inlet and outlet 6 assembly of the quasi-isothermal expansion axial flow turbine is connected to the reactor 13 through the eighth pipeline, the heat exchanger 12 is connected to the reactor 13 through the ninth pipeline, and the reactor 13 is connected to the medium inlet and outlet 6 assembly of the quasi-isothermal expansion axial flow turbine through the tenth pipeline; the seventh pipeline, the eighth pipeline, the ninth pipeline and the tenth pipeline are all used to transport the heating medium 3; the rotating shaft 1 of the quasi-isothermal expansion axial flow turbine is connected to the generator 14;

[0055] With such a setting, except for the expansion link, the other parts of the quasi-isothermal expansion nuclear power generation system of the present invention have no obvious difference from the common SCO 2 Brayton cycle system. After the SCO 2 working fluid enters the compressor 9 and is compressed, it enters the regenerator 11 to exchange heat with the high-temperature and low-pressure working fluid coming out of the turbine, and then enters the heat exchanger 12 to exchange heat with the heat exchange medium of the reactor 13, and is further heated to the high-temperature and high-pressure state. After the high-temperature and high-pressure working fluid enters the turbine, it undergoes a quasi-isothermal process of expanding and absorbing heat in the turbine, and becomes a high-temperature and low-pressure working fluid, which enters the regenerator to release heat, and so on in a cycle;

[0056] The cycle temperature-entropy diagram of the quasi-isothermal expansion nuclear power generation system of the present invention is as Figure 4 shown. O-PT is the ideal isothermal expansion process, and the actual expansion process is along O-P. It can be seen that compared with the reheat expansion, the work done by the quasi-isothermal expansion cycle is more.

[0057] Embodiment 2

[0058] Referring to Figure 7 , the difference between this embodiment and Embodiment 1 is that this embodiment provides a quasi-isothermal expansion radial flow turbine expander, which includes an impeller 16, an end cover 17 and a volute 15;

[0059] The inside of the end cover 17 and the volute 15 is a hollow structure, and the heating medium 3 is introduced to heat the working fluid during the expansion process.

[0060] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention.

[0061] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A quasi-isothermal expansion axial flow turbine, characterized in that: include: A shell (5), a plurality of stationary blades (2) are arranged on the inner wall of the shell (5); the plurality of stationary blades (2) are arranged at intervals along the inner wall of the shell (5); the transverse cross-section of the stationary blade (2) is annular, a plurality of passages (8) are penetrated through the side wall of the stationary blade (2), the plurality of passages (8) are arranged circumferentially along the axis of the stationary blade (2), a first channel is arranged between the passage (8) and the inner ring of the stationary blade (2), a second channel is arranged between the passage (8) and the outer ring of the stationary blade (2), a third channel is arranged between two adjacent passages (8), and the first channel and the second channel are connected through the plurality of third channels; the passage (8) is used for circulating SCO2 working fluid; A rotating shaft (1), the rotating shaft (1) being rotatably connected in the housing (5), the rotating shaft (1) penetrating the inner ring of the stationary blade (2); a plurality of moving blades (4) being mounted on the rotating shaft (1), the plurality of moving blades (4) being arranged at intervals along the axial direction of the rotating shaft (1), and the plurality of moving blades (4) and the plurality of stationary blades (2) being arranged alternately; A medium inlet and outlet (6) component, wherein the medium inlet and outlet (6) component is mounted on the housing (5) and is connected to the second channel for introducing a heating medium (3) into the second channel.

2. The quasi-isothermal expansion axial flow turbine according to claim 1, characterized in that: The medium inlet and outlet (6) assembly comprises an outlet (6) and an inlet (7), wherein the outlet (6) and the inlet (7) are both mounted on the housing (5), wherein the outlet (6) is fixedly connected to the top of the outer ring of the stationary blade (2), and the inlet (7) is fixedly connected to the bottom of the outer ring of the stationary blade (2), and wherein the outlet (6) and the inlet (7) are both connected to the second channel.

3. The quasi-isothermal expansion axial flow turbine according to claim 1, characterized in that: The heating medium (3) includes but is not limited to liquid sodium or water vapor.

4. The quasi-isothermal expansion axial flow turbine according to claim 1, characterized in that: The plurality of passages (8) are arranged at equal intervals in the circumferential direction of the axis of the stationary blade (2).

5. A quasi-isothermal expansion nuclear power generation system, comprising the quasi-isothermal expansion axial flow turbine according to any one of claims 1 to 4, characterized in that: It also includes a compressor (9), a cooler (10), a regenerator (11), a heat exchanger (12), a reactor (13) and a generator (14); The compressor (9) is connected to the regenerator (11) via a second pipeline, the regenerator (11) is connected to the heat exchanger (12) via a third pipeline, the heat exchanger (12) is connected to the passage (8) of the quasi-isothermal expansion axial flow turbine via a fourth pipeline, the passage (8) of the quasi-isothermal expansion axial flow turbine is connected to the regenerator (11) via a fifth pipeline, the regenerator (11) is connected to the cooler (10) via a sixth pipeline, and the cooler (10) is connected to the compressor (9) via a first pipeline; the first pipeline, the second pipeline, the third pipeline, the fourth pipeline, the fifth pipeline and the sixth pipeline are all used for conveying SCO2 working medium; The reactor (13) is connected to the heat exchanger (12) via a seventh pipeline, the medium inlet and outlet (6) components of the quasi-isothermal expansion axial flow turbine are connected to the reactor (13) via an eighth pipeline, the heat exchanger (12) is connected to the reactor (13) via a ninth pipeline, and the reactor (13) is connected to the medium inlet and outlet (6) components of the quasi-isothermal expansion axial flow turbine via a tenth pipeline; the seventh pipeline, the eighth pipeline, the ninth pipeline, and the tenth pipeline are all used to transport the heating medium (3); the rotating shaft (1) of the quasi-isothermal expansion axial flow turbine is connected to the generator (14).

Images