A supercritical carbon dioxide inter-stage reheat turbo system

Abstract

The application discloses a supercritical carbon dioxide interstage reheat turbine system, which comprises a supercritical carbon dioxide heat supply system and a supercritical carbon dioxide recompression cycle power generation system, the supercritical carbon dioxide heat supply system is used for supplying heat to supercritical carbon dioxide of the supercritical carbon dioxide recompression cycle power generation system, and the supercritical carbon dioxide recompression cycle power generation system comprises a turbine; the supercritical carbon dioxide heat supply system comprises a first high-temperature heat storage medium tank and a second high-temperature heat storage medium tank, the first high-temperature heat storage medium tank is communicated with a heat exchanger, and supercritical carbon dioxide passing through the heat exchanger is heated; the heated supercritical carbon dioxide enters the turbine; and the second high-temperature heat storage medium tank provides heat to the supercritical carbon dioxide in the turbine through a heat pipe system. The application realizes the functions of improving turbine power and power generation capacity without increasing the number of reheat platforms, and further improves the efficiency of the supercritical carbon dioxide turbine system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of supercritical carbon dioxide power generation, and particularly relates to a supercritical carbon dioxide inter-stage reheat turbine system. BACKGROUND

[0002] Supercritical carbon dioxide power generation technology is generally considered to be the next generation of revolutionary power generation technology due to its high power generation efficiency, environmental protection and no pollution, etc. In the region above 600℃, it has obvious advantages compared with the existing steam cycle power generation technology. Supercritical carbon dioxide power generation technology is based on the principle of Brayton cycle. However, supercritical carbon dioxide power generation technology is just emerging, and its cost is much higher than that of steam power generation unit under the same power generation power level, so it is necessary to further improve the power generation efficiency of supercritical carbon dioxide cycle.

[0003] The power generation equipment based on the principle of Brayton cycle with supercritical carbon dioxide as working medium is supercritical carbon dioxide turbine. Supercritical CO2 is a carbon dioxide fluid with temperature and pressure higher than the critical value (Tc=30.98℃, Pc=7.38MPa). Supercritical fluid is between gas and liquid, and also has the physical and chemical properties of gas and liquid. Compared with other same type of cycle working medium, supercritical carbon dioxide has the general characteristics of supercritical fluid and other unique characteristics: 1) density close to liquid, 2 orders of magnitude larger than gas; superheat efficiency is high, and work capacity is strong; 2) viscosity close to gas, 2 orders of magnitude smaller than liquid; strong flowability, easy to diffuse, and small system cycle loss. The Brayton cycle is a typical thermodynamic cycle, which consists of two isobaric and two adiabatic processes (adiabatic compression, isobaric heat absorption, adiabatic expansion and isobaric cooling 4 processes), and the working medium does not change phase in the cycle.

[0004] The work temperature of supercritical carbon dioxide turbine is a very important factor affecting the power generation efficiency. The higher the inlet temperature, the higher the power generation efficiency, so the work temperature of supercritical carbon dioxide turbine needs to be improved.

[0005] Due to the limitation of materials, if the turbine inlet temperature is increased to improve the power generation efficiency, the cost will inevitably increase by several times, and there is a temperature limit.

[0006] In the steam cycle, there is a design of reheat cycle, that is, two turbines are set, the working medium after work of the high-pressure turbine is heated and then enters the low-pressure turbine to continue to work, so as to increase the power generation and improve the power generation efficiency. However, in the supercritical carbon dioxide power generation cycle, the cost of supercritical carbon dioxide turbine is high, and the design of reheat cycle is not realistic, and the addition of one turbine will bring secondary loss of gas leakage, and the overall efficiency improvement is not obvious. Therefore, how to improve the work temperature of supercritical carbon dioxide turbine is a difficulty. SUMMARY

[0007] The embodiment of the present application provides a supercritical carbon dioxide inter-stage reheating turbine system, which realizes the improvement of turbine working temperature and power generation capacity without increasing the number of reheating turbines, and further improves the supercritical carbon dioxide power generation efficiency.

[0008] To achieve the above object, the technical scheme of the embodiment of the present application is as follows:

[0009] A supercritical carbon dioxide inter-stage reheating turbine system, comprising a supercritical carbon dioxide heat supply system and a supercritical carbon dioxide recompression cycle power generation system, wherein the supercritical carbon dioxide heat supply system is used to supply heat to supercritical carbon dioxide of the supercritical carbon dioxide recompression cycle power generation system, and the supercritical carbon dioxide recompression cycle power generation system comprises a turbine, which utilizes supercritical carbon dioxide output mechanical energy to generate electricity by using a generator.

[0010] The supercritical carbon dioxide heat supply system is connected with the supercritical carbon dioxide recompression cycle power generation system through a heat exchanger, the supercritical carbon dioxide heat supply system comprises a first high-temperature heat storage medium tank and a second high-temperature heat storage medium tank, the first high-temperature heat storage medium tank is communicated with the heat exchanger and heats supercritical carbon dioxide passing through the heat exchanger, and the second high-temperature heat storage medium tank supplies heat to supercritical carbon dioxide in the turbine through a heat pipe system.

[0011] The heat pipe system comprises a heat pipe heat absorption section and a heat pipe heat release section, the heat pipe heat absorption section is arranged in the second high-temperature heat storage medium tank, the heat pipe heat release section is arranged in the turbine, high-temperature heat storage medium in the second high-temperature heat storage medium tank transmits heat to the heat pipe heat absorption section, and then transmits heat to the heat pipe heat release section, and finally heat is transmitted to supercritical carbon dioxide in the turbine through the heat pipe heat release section.

[0012] A plurality of first shafts and a plurality of second shafts are arranged in the cavity of the turbine, the plurality of first shafts comprise a first stage, a second stage, a third stage and the like, the plurality of second shafts also comprise a first stage, a second stage, a third stage and the like, the first shafts and the second shafts are arranged at intervals, i.e. a first stage first shaft, a first stage second shaft, a second stage first shaft, a second stage second shaft and the like are arranged in sequence from a supercritical carbon dioxide inlet to an outlet, the first shafts are all fixed on the cavity wall, the second shafts are all connected with a rotating shaft, a plurality of static blades are arranged on the first shafts, a plurality of dynamic blades are arranged on the second shafts, the rotating shaft is connected with the generator, and the heat pipe heat release section is arranged in the first shaft and used to heat the first shaft and the static blades.

[0013] The supercritical carbon dioxide entering the inner cavity of the turbine passes through the first stage first shaft, which is fixed on the cavity wall, so that heat is transferred to the supercritical carbon dioxide, the temperature of the supercritical carbon dioxide is increased, the enthalpy is increased, the work capacity is increased, and then the supercritical carbon dioxide passes through the first stage moving blade, and since the second shaft is connected to the rotating shaft, the supercritical carbon dioxide drives the second shaft to rotate by work, so that the internal energy is converted into kinetic energy, the rotation of the second shaft drives the rotating shaft, and the rotating shaft further drives the generator to generate electricity, and the temperature of the supercritical carbon dioxide is decreased after passing through the first stage second shaft, and then the supercritical carbon dioxide passes through the second stage first shaft, the second stage second shaft, the third stage first shaft, and the third stage second shaft, so that the temperature of the supercritical carbon dioxide is increased, the enthalpy is increased, the work capacity is increased, and the power generation capacity is increased.

[0014] Since the supercritical carbon dioxide entering the turbine absorbs the heat of the high-temperature heat storage medium in the first high-temperature heat storage medium tank, the heat pipe heat releasing section is arranged in the other first shafts except the first shaft close to the supercritical carbon dioxide inlet, that is, all the first shafts except the first stage first shaft.

[0015] The cavity of the turbine is provided with at least three first shafts, that is, the first shaft is provided with at least three stages, and the heat pipe heat releasing section is arranged in the second stage first shaft and the third stage first shaft except the first stage first shaft, since there is a large heat loss when the supercritical carbon dioxide is transferred to the second shaft through each stage first shaft, the heat of the second high-temperature heat storage medium is heated to the second stage first shaft and the third stage first shaft in stages in the embodiment of the present application, so that the heat loss is reduced, the energy utilization rate is high, and since each stage of the turbine does not have to bear a too high temperature, the structure of the turbine is simple and the reliability is high.

[0016] The heat pipe heat releasing section and the heat pipe heat absorbing section are both provided with fins to increase the area of heat exchange.

[0017] The supercritical carbon dioxide recompression cycle power generation system further comprises a high-temperature regenerator, a low-temperature regenerator, a main cooler, a main compressor, and a recompression compressor, the high-temperature regenerator has two inlets and two outlets, the low-temperature regenerator has two inlets and two outlets, the first outlet of the high-temperature regenerator is connected to the heat exchanger, the heat exchanger is connected to the inlet of the turbine, the outlet of the turbine is connected to the first inlet of the high-temperature regenerator, the second outlet of the high-temperature regenerator is connected to the first inlet of the low-temperature regenerator, the first outlet of the low-temperature regenerator is connected to the inlet of the main cooler, the outlet of the main cooler is divided into two paths, one path is connected to the inlet of the main compressor, and the other path is connected to the inlet of the recompression compressor, the outlet of the main compressor is connected to the second inlet of the low-temperature regenerator, and the second outlet of the low-temperature regenerator and the outlet of the recompression compressor are both connected to the second inlet of the high-temperature regenerator.

[0018] The supercritical carbon dioxide at the outlet of the turbine first enters a high-temperature regenerator to release heat, then enters a low-temperature regenerator to exchange heat again, then the supercritical carbon dioxide is directly led to a main cooler to be cooled, and then a part is directly led to a main compressor to be compressed, and after compression, enters the low-temperature regenerator to exchange heat, and another part is led to a re-compressor to be compressed, and then mixed with the supercritical carbon dioxide passing through the low-temperature regenerator, and then flows through the high-temperature regenerator, and then exchanges heat with the high-temperature heat storage medium in the first high-temperature heat storage medium tank to enter the turbine.

[0019] The supercritical carbon dioxide power generation system is applied to the field of photothermal power generation, so that the supercritical carbon dioxide heat supply system is a molten salt circulation system, the first high-temperature heat storage medium tank is a first high-temperature molten salt tank, the second high-temperature heat storage medium tank is a second high-temperature molten salt tank, the molten salt circulation system further comprises a low-temperature molten salt tank and a heat absorber, the outlet of the first high-temperature molten salt tank is connected to the inlet of the low-temperature molten salt tank through the heat exchanger, the outlet of the second high-temperature molten salt tank and the outlet of the low-temperature molten salt tank are both connected to the inlet of the heat absorber, and the outlet of the heat absorber is connected to the inlet of the first high-temperature molten salt tank and the inlet of the second high-temperature molten salt tank.

[0020] The present application has the following advantages and positive effects compared with the prior art due to the adoption of the above technical scheme:

[0021] The present application has the following advantages and positive effects compared with the prior art due to the adoption of the above technical scheme: BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure is a photothermal power generation supercritical carbon dioxide power generation circulation system diagram of an embodiment of the present application;

[0023] Figure 2 The figure is a heat exchange diagram of the turbine and the second high-temperature heat storage medium tank of the present application.

[0024] Explanation of reference numerals in the attached drawings: 1-Turbine; 2-High-temperature regenerator; 201-First inlet of high-temperature regenerator; 202-First outlet of high-temperature regenerator; 203-Second inlet of high-temperature regenerator; 204-Second outlet of high-temperature regenerator; 3-Low-temperature regenerator; 301-First inlet of low-temperature regenerator; 302-First outlet of low-temperature regenerator; 303-Second inlet of low-temperature regenerator; 304-Second outlet of low-temperature regenerator; 4-Main cooler; 5-Main compressor 6-Recompressor; 7-First high-temperature molten salt tank; 8-Second high-temperature molten salt tank; 9-Heat exchanger; 10-Low-temperature molten salt tank; 11-Absorber; 12-Shaft; 13-First stage first shaft; 14-First stage second shaft; 15-Heat pipe heat dissipation section; 16-Heat pipe heat absorption section; 17-Cavity wall; 18-Second stage first shaft; 19-Second stage second shaft; 20-Third stage first shaft; 21-Third stage second shaft; 22-Fourth stage first shaft; 23-Fourth stage second shaft. Detailed Implementation

[0025] The supercritical carbon dioxide interstage reheat turbine system proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description and claims.

[0026] This embodiment applies a supercritical carbon dioxide power generation system to the power generation stage of a concentrated solar power (CSP) system.

[0027] See Figure 1 A supercritical carbon dioxide interstage reheat turbine system includes a molten salt cycle system and a supercritical carbon dioxide recompression cycle power generation system. The molten salt cycle system is used to provide heat to the supercritical carbon dioxide in the supercritical carbon dioxide recompression cycle power generation system. The supercritical carbon dioxide recompression cycle power generation system includes a turbine 1. The supercritical carbon dioxide flows through the turbine, performs work and outputs mechanical energy, and then generates electricity.

[0028] The molten salt circulation system is connected to the supercritical carbon dioxide recompression cycle power generation system through heat exchanger 9. The molten salt circulation system includes a first high-temperature molten salt tank 7 and a second high-temperature molten salt tank 8. The first high-temperature molten salt tank 7 is connected to the heat exchanger 9 and heats the supercritical carbon dioxide passing through the heat exchanger 9. The supercritical carbon dioxide flows into the turbine 1 after passing through the heat exchanger 9. The second high-temperature molten salt tank 8 provides heat to the supercritical carbon dioxide in the turbine 1 through a heat pipe system.

[0029] The heat pipe system includes a heat pipe heat absorption section 16 and a heat pipe heat dissipation section 15. The heat pipe heat absorption section 16 is located inside the second high-temperature molten salt tank 8, and the heat pipe heat dissipation section 15 is located inside the turbine 1.

[0030] The turbine 1 has a cavity inside, and a plurality of first shafts and a plurality of second shafts are arranged in the cavity. In the embodiment, the plurality of first shafts include a first-stage first shaft 13, a second-stage first shaft 18, a third-stage first shaft 20, and a fourth-stage first shaft 22, and the plurality of second shafts also include a first-stage second shaft 14, a second-stage second shaft 19, a third-stage second shaft 21, and a fourth-stage second shaft 23. The first shafts and the second shafts are arranged at intervals, that is, the first-stage first shaft 13, the first-stage second shaft 14, the second-stage first shaft 18, the second-stage second shaft 19, the third-stage first shaft 20, the third-stage second shaft 21, the fourth-stage first shaft 22, and the fourth-stage second shaft 23 are sequentially arranged from the supercritical carbon dioxide inlet to the supercritical carbon dioxide outlet, as shown in FIG. 1. Figure 2 The first shafts are all fixed on the cavity wall 17, and the second shafts are all connected to a rotating shaft 12. A plurality of stationary vanes are arranged on the first shafts, and a plurality of moving vanes are arranged on the second shafts. The rotating shaft 12 is connected to a generator. The heat pipe heat releasing section 15 is arranged in the first shaft. The high-temperature molten salt in the second high-temperature molten salt tank 8 transmits heat to the heat pipe heat absorbing section 16, and then to the heat pipe heat releasing section 15. Finally, the heat is transmitted to the first shafts and the stationary vanes through the heat pipe heat releasing section 15.

[0031] The supercritical carbon dioxide entering the cavity of the turbine 1 passes through the first-stage first shaft 13. The first-stage first shaft 13 is fixed on the cavity wall 17, so heat is transmitted to the supercritical carbon dioxide. The temperature of the supercritical carbon dioxide increases, the enthalpy increases, and the work capacity increases. Then, when the supercritical carbon dioxide passes through the first-stage moving vanes, the second shaft is connected to the rotating shaft 12, so the supercritical carbon dioxide drives the second shaft to rotate, converting internal energy into kinetic energy. The rotation of the second shaft drives the rotating shaft 12, which in turn drives the generator to generate electricity. After the supercritical carbon dioxide passes through the first-stage second shaft 14, the temperature decreases. The supercritical carbon dioxide passes through the second-stage first shaft 18, the second-stage second shaft 19, the third-stage first shaft 20, the third-stage second shaft 21, the fourth-stage first shaft 22, and the fourth-stage second shaft 23. Therefore, the temperature of the supercritical carbon dioxide increases, the enthalpy increases, the work capacity increases, and the power generation capacity increases.

[0032] In the embodiment, the number of heated first shafts can be one, two, three, or four. Since the supercritical carbon dioxide entering the turbine 1 absorbs the heat of the high-temperature molten salt in the first high-temperature molten salt tank 7, the heat pipe heat releasing section 15 is preferably arranged in the first shafts other than the first shaft close to the supercritical carbon dioxide inlet, that is, in all the first shafts except the first-stage first shaft 13.

[0033] The heat pipe heat releasing section 15 and the heat pipe heat absorbing section 16 are both provided with fins to increase the area of heat exchange.

[0034] The supercritical carbon dioxide re-compression cycle power generation system further comprises a high-temperature regenerator 2, a low-temperature regenerator 3, a main cooler 4, a main compressor 5, and a re-compressor 6, the high-temperature regenerator 2 has two inlets and two outlets, the low-temperature regenerator 3 has two inlets and two outlets, the first outlet 202 of the high-temperature regenerator is connected to the heat exchanger 9, the heat exchanger 9 is connected to the inlet of the turbine 1, the outlet of the turbine 1 is connected to the first inlet 201 of the high-temperature regenerator, the second outlet 204 of the high-temperature regenerator is connected to the first inlet 301 of the low-temperature regenerator, the first outlet 302 of the low-temperature regenerator is connected to the inlet of the main cooler 4, the outlet of the main cooler 4 is divided into two paths, one path is connected to the inlet of the main compressor 5, and the other path is connected to the inlet of the re-compressor 6, the outlet of the main compressor 5 is connected to the second inlet 303 of the low-temperature regenerator, and the second outlet 304 of the low-temperature regenerator and the outlet of the re-compressor 6 are both connected to the second inlet 203 of the high-temperature regenerator.

[0035] The supercritical carbon dioxide at the outlet of the turbine 1 is first subjected to heat release in the high-temperature regenerator 2, then subjected to heat exchange in the low-temperature regenerator 3, and then directly sent to the main cooler 4 for cooling, and then a part is directly sent to the main compressor 5 for compression, and the compressed supercritical carbon dioxide is subjected to heat exchange in the low-temperature regenerator 3, and the other part is sent to the re-compressor 6 for compression, and then mixed with the supercritical carbon dioxide that has passed through the low-temperature regenerator 3, and then flows through the high-temperature regenerator 2 again, and then subjected to heat exchange with the high-temperature molten salt in the first high-temperature molten salt tank 7 and then enters the turbine 1.

[0036] The molten salt circulation system further comprises a low-temperature molten salt tank 10 and a heat absorber 11, the outlet of the first high-temperature molten salt tank 7 is connected to the inlet of the low-temperature molten salt tank 10 through the heat exchanger 9, the outlets of the low-temperature molten salt tank 10 and the second high-temperature molten salt tank 8 are connected to the inlet of the heat absorber 11, and the outlet of the heat absorber 11 is connected to the inlets of the first high-temperature molten salt tank 7 and the second high-temperature molten salt tank 8.

[0037] The high-temperature molten salt in the first high-temperature molten salt tank 7 transmits heat to the supercritical carbon dioxide through the heat exchanger 9, and then enters the low-temperature molten salt tank 10, the low-temperature molten salt in the low-temperature molten salt tank 10 absorbs solar energy through the heat absorber 11, the molten salt in the second high-temperature molten salt tank 8 is directly subjected to heat exchange and then enters the heat absorber 11 to absorb solar energy, and the molten salt that has absorbed solar energy in the heat absorber 11 returns to the first high-temperature molten salt tank 7 and the second high-temperature molten salt tank 8.

[0038] In this embodiment, the first high-temperature molten salt tank 7 exchanges heat with the supercritical carbon dioxide entering the turbine 1, then the second high-temperature molten salt tank 8 exchanges heat with the supercritical carbon dioxide entering the turbine 1, and the supercritical carbon dioxide that has done work and been cooled exchanges heat, and the inter-stage reheat system is arranged, so that the turbine working temperature is increased and the power generation capacity is increased without increasing the number of reheat turbine stages, and the supercritical carbon dioxide power generation efficiency is further improved.

[0039] The embodiments of the present application are explained in detail above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments. Even if various changes are made to the present application, provided that the changes fall within the scope of the present application claims and equivalent technologies thereof, they still fall within the scope of the present application.

Claims

1. A supercritical carbon dioxide inter-stage reheat turbo system, characterized by, The supercritical carbon dioxide heating system and the supercritical carbon dioxide re-compression cycle power generation system, the supercritical carbon dioxide heating system is used for providing heat for the supercritical carbon dioxide of the supercritical carbon dioxide re-compression cycle power generation system, the supercritical carbon dioxide re-compression cycle power generation system includes a turbine; The supercritical carbon dioxide heating system is connected with the supercritical carbon dioxide re-compression cycle power generation system through a heat exchanger, the supercritical carbon dioxide heating system includes a first high-temperature heat storage medium tank and a second high-temperature heat storage medium tank, the first high-temperature heat storage medium tank is communicated with the heat exchanger and heats the supercritical carbon dioxide passing through the heat exchanger, and the heated supercritical carbon dioxide enters the turbine, the second high-temperature heat storage medium tank provides heat for the supercritical carbon dioxide in the turbine through a heat pipe system; The heat pipe system includes a heat pipe heat absorption section and a heat pipe heat release section, the heat pipe heat absorption section is arranged in the second high-temperature heat storage medium tank, and the heat pipe heat release section is arranged in the turbine; A plurality of first shafts and a plurality of second shafts are arranged in the cavity of the turbine, the first shafts and the second shafts are arranged at intervals, the first shafts are all fixed on the cavity wall, the second shafts are all connected with a rotating shaft, the rotating shaft is connected with a generator, and the heat pipe heat release section is arranged in the first shaft.

2. The supercritical carbon dioxide inter-stage reheat turbo system of claim 1, wherein, The heat pipe heat release section is arranged in the first shafts except the first shafts close to the supercritical carbon dioxide inlet.

3. The supercritical carbon dioxide inter-stage reheat turbo system of claim 2, wherein, At least three first shafts are arranged in the cavity of the turbine.

4. The supercritical carbon dioxide inter-stage reheat turbo system of claim 1, wherein, The heat pipe heat release section and the heat pipe heat absorption section are both provided with fins.

5. The supercritical carbon dioxide inter-stage reheat turbo system of any one of claims 1-4, wherein, The supercritical carbon dioxide re-compression cycle power generation system further includes a high-temperature regenerator, a low-temperature regenerator, a main cooler, a main compressor and a re-compressor, the high-temperature regenerator has two inlets and two outlets, the low-temperature regenerator has two inlets and two outlets, the first outlet of the high-temperature regenerator is connected with the heat exchanger, the heat exchanger is connected with the inlet of the turbine, the outlet of the turbine is connected with the first inlet of the high-temperature regenerator, the second outlet of the high-temperature regenerator is connected with the first inlet of the low-temperature regenerator, the first outlet of the low-temperature regenerator is connected with the inlet of the main cooler, the outlet of the main cooler is divided into two paths, one path is connected with the inlet of the main compressor, and the other path is connected with the inlet of the re-compressor, the outlet of the main compressor is connected with the second inlet of the low-temperature regenerator, and the second outlet of the low-temperature regenerator and the outlet of the re-compressor are both connected with the second inlet of the high-temperature regenerator.

6. The supercritical carbon dioxide inter-stage reheat turbo system of any one of claims 1-4, wherein, The supercritical carbon dioxide heating system is a molten salt circulation system, the first high-temperature heat storage medium tank is a first high-temperature molten salt tank, the second high-temperature heat storage medium tank is a second high-temperature molten salt tank, the molten salt circulation system further includes a low-temperature molten salt tank and a heat absorber, the outlet of the first high-temperature molten salt tank is connected with the inlet of the low-temperature molten salt tank through the heat exchanger, the outlet of the second high-temperature molten salt tank and the outlet of the low-temperature molten salt tank are both connected with the inlet of the heat absorber, and the outlet of the heat absorber is connected with the inlet of the first high-temperature molten salt tank and the inlet of the second high-temperature molten salt tank.

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