SC-CO2 power generation system, SC-CO2 auxiliary heating system and solar thermal power generation system

Abstract

The application discloses an SC-CO2 power generation system, an SC-CO2 auxiliary heating system and a solar thermal power generation system, and relates to the technical field of supercritical carbon dioxide auxiliary heating systems.The supercritical carbon dioxide auxiliary heating system comprises a first heat storage medium heat exchanger, which is in communication with a heat storage system of the solar thermal power station; an auxiliary heater, which further comprises a burner and a hearth, wherein the burner is in communication with the hearth; and a first heat exchange pipe, wherein carbon dioxide is introduced into the first heat exchange pipe, the first heat exchange pipe passes through cavities of the first heat storage medium heat exchanger and the hearth in the direction of carbon dioxide flow, the first heat storage medium heat exchanger is used for initial heating of the carbon dioxide, and the auxiliary heater is used for re-heating of the initially heated carbon dioxide.The application solves the problem that the solar salt heat exchange system in the solar thermal power generation system cannot meet the temperature requirement (620 DEG C or above) of the heat exchange medium of the supercritical carbon dioxide power generation system.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of solar thermal power generation systems, and particularly relates to an SC-CO2 (supercritical carbon dioxide) auxiliary heating system in an SC-CO2 (supercritical carbon dioxide) power generation system, an SC-CO2 (supercritical carbon dioxide) power generation system and a solar thermal power generation system. BACKGROUND

[0002] Thermal power generation is a traditional form of solar power generation technology, which has the advantages of high power generation efficiency, system output grid adaptability and obvious power generation scale benefit.

[0003] Supercritical carbon dioxide (SC-CO2) power generation has obvious efficiency advantages compared with water vapor power generation at a scale of 600 DEG C or above and ten to one hundred megawatt installed capacity. In addition, compared with water vapor power generation, supercritical carbon dioxide power generation also has the advantages of small equipment size and simple system. Therefore, supercritical carbon dioxide power generation is considered to be one of the most potential technologies in the third generation of solar thermal power generation technology.

[0004] It is worth noting that the supercritical carbon dioxide power generation system has a high requirement for the temperature of the medium, which needs to reach 620 DEG C or above. The existing solar salt heat exchange system (heat storage temperature 565 DEG C) cannot meet the heat exchange temperature requirement of the supercritical carbon dioxide system. At the same time, the high-temperature medium technology (medium temperature reaching 650 DEG C or above) is still in the research and development stage, and many problems such as equipment material and physical property stability are still under study, and it does not have commercial application ability. SUMMARY

[0005] In view of the above technical problems, the application provides an SC-CO2 (supercritical carbon dioxide) power generation system, an SC-CO2 (supercritical carbon dioxide) auxiliary heating system and a solar thermal power generation system, which solve the problem that the solar salt heat exchange system in the solar thermal power generation system cannot meet the heat exchange medium temperature requirement (need to reach 620 DEG C or above) of the supercritical carbon dioxide power generation system.

[0006] To achieve the above purpose, the technical scheme of the application is as follows:

[0007] A supercritical carbon dioxide auxiliary heating system for a solar thermal power station, comprising:

[0008] A first heat storage medium heat exchanger in communication with a heat storage system of the solar thermal power station;

[0009] An auxiliary heater further comprising a combustor and a furnace, the combustor being in communication with the furnace;

[0010] The first heat exchange pipe, into which carbon dioxide flows, passes through the first heat medium heat exchanger for initial heating of the carbon dioxide and the cavity of the furnace.

[0011] The auxiliary heating system further comprises a second heat medium energy storage system, which comprises a plurality of heat storage tanks, each of which is filled with a second heat medium, and the heat storage tanks are arranged in the furnace to heat the second heat medium in the heat storage tanks while heating the carbon dioxide medium.

[0012] The first heat exchange pipe passes through the heat storage tank, and the heat energy stored in the heat storage tank is used to heat the carbon dioxide in the first heat exchange pipe.

[0013] In the direction of the flow of carbon dioxide, the heat storage tanks are arranged at intervals, and the first heat exchange pipe passes through the heat storage tanks to form interval heating, which can make the overall heating of the first heat exchange pipe uniform, and the carbon dioxide can relatively slowly transition from a liquid-like state to a gas-like state during the warming process, avoiding the short-term temperature change when supercritical carbon dioxide crosses the pseudo-critical line, which can cause a large fluctuation in the physical parameters of supercritical carbon dioxide.

[0014] In the direction of the flow of carbon dioxide, the distance between adjacent heat storage tanks gradually increases, which can ensure that the temperature of the carbon dioxide in the first heat exchange pipe rises relatively smoothly.

[0015] The second heat medium energy storage system further comprises a liquid charger, which is in communication with the heat storage tanks to charge or discharge the second heat medium.

[0016] The auxiliary heating system further comprises a flue gas treatment system, which comprises a compressor, a vortex chamber, a hot stream pipe, and a second heat exchange pipe, the inlet of the compressor is in communication with the flue gas outlet of the furnace, the outlet of the compressor is in communication with the inlet of the vortex chamber, the high-temperature outlet of the vortex chamber is in communication with the hot stream pipe, and the hot stream pipe is in communication with the second heat exchange pipe through a delivery pipe.

[0017] The second heat medium energy storage system further comprises a heat exchange chamber, one side of which is in communication with the heat storage tanks, and the other side is in communication with the liquid charger.

[0018] The second heat exchange pipe is arranged inside the heat exchange chamber.

[0019] The high-temperature flue gas generated in the furnace enters the vortex chamber, and the secondary heated hot gas stream passes through the second heat exchange pipe to heat the second heat medium again.

[0020] The outer wall of the furnace is provided with a ring channel, which is communicated with the upper part of the furnace;

[0021] The bottom of the ring channel is communicated with the inlet of the compressor. The flue gas in the furnace is transported to the outside of the furnace through the ring channel, which surrounds the circumference of the furnace and can be used as a heat preservation layer of the furnace.

[0022] The end of the heat pipe near the second heat exchange pipe is communicated with the conveying pipe through the gas distribution cavity, and the diameter of the gas distribution cavity decreases from large to small in the direction of gas flow. When the high-temperature flue gas flows into the second heat exchange pipe, the high-temperature gas first flows to the variable-diameter gas distribution cavity, and the pressure gradient is formed inside the gas distribution cavity, which is beneficial to the uniform distribution of hot gas.

[0023] Based on the same concept, the application also provides a supercritical carbon dioxide power generation system for a solar thermal power station, comprising the supercritical carbon dioxide auxiliary heating system for a solar thermal power station.

[0024] Based on the same concept, the application also provides a solar thermal power generation system, comprising the supercritical carbon dioxide power generation system for a solar thermal power station.

[0025] The application has the following advantages and positive effects compared with the prior art due to the use of the above technical scheme:

[0026] In the embodiment of the application, after the first heat exchange medium heat exchanger preliminarily heats the carbon dioxide, the auxiliary heater is arranged to heat the carbon dioxide again, so that the temperature of the carbon dioxide reaches the required temperature for carbon dioxide power generation, and then the heated carbon dioxide is used in the subsequent power generation system, thereby solving the problem that the solar salt heat exchange system in the solar thermal power generation system cannot meet the temperature requirement (which needs to reach more than 620 DEG C) of the heat exchange medium of the supercritical carbon dioxide power generation system.

[0027] In another embodiment of the application, the second heat storage medium energy storage system is also included, the heat storage tank filled with the second heat storage medium is placed in the furnace, and the second heat storage medium is heated for energy storage while the carbon dioxide is heated. Preferably, the first heat exchange pipe filled with carbon dioxide penetrates through the heat storage tank of the second heat storage medium energy storage system. When the burner is not working, the heat energy stored in the heat storage tank can be used to heat and raise the temperature of the carbon dioxide. When the burner is working, the carbon dioxide is mainly heated by the high-temperature flue gas, thereby realizing the integration of heat storage and heat exchange, and the flexible regulation and control according to the requirement.

[0028] Meanwhile, in the direction of the carbon dioxide flow, a plurality of heat storage grooves are arranged, each of the heat storage grooves is a heated section in contact with the first heat exchange pipe, and between adjacent heated sections, a section not in contact with the heat storage groove is arranged, forming a form of interval heating. By using the interval heating form, the heating amount of the whole first heat exchange pipe heated section is approximately the same, and the area between the interval heated sections can make the supercritical carbon dioxide temperature rise slowly. The above characteristics can make the critical carbon dioxide relatively slowly transition from the liquid-like zone to the gas-like zone during the temperature rising process, avoid the short time temperature zone change when the supercritical carbon dioxide crosses the pseudo critical line, and cause the supercritical carbon dioxide physical property parameters to fluctuate greatly.

[0029] In another embodiment of the present application, a flue gas treatment system is arranged, and a vortex chamber is arranged in the flue gas treatment system. By the separation effect of the vortex, the flue gas after the first heat exchange is heated again to heat the second heat storage medium for the second time, forming the second heat storage of heat energy. The high-temperature flue gas in the furnace is discharged outside the furnace through the ring channel and enters the vortex chamber. Meanwhile, the high-temperature flue gas in the ring channel also has a heat preservation function, which is helpful for heat preservation of the second heat storage medium in the heat storage groove or the high-temperature flue gas in the furnace, and avoids heat loss. BRIEF DESCRIPTION OF DRAWINGS

[0030] Fig. 1 It is a transverse sectional view of the supercritical carbon dioxide auxiliary heating system for the solar thermal power station of embodiment 1 of the present application;

[0031] Fig. 2 It is a longitudinal sectional view of the supercritical carbon dioxide auxiliary heating system for the solar thermal power station of embodiment 1 of the present application;

[0032] Explanation of reference signs: 1-burner; 2-furnace; 3-first heat storage medium heat exchanger; 301-first heat storage medium inlet; 302-first heat storage medium outlet; 4-first heat exchange pipe; 5-heat storage groove; 6-liquid flushing device; 7-conveying pipe; 8-heat exchange cavity; 9-ring channel; 10-compressor; 11-vortex chamber; 12-hot flow pipe; 13-cold flow pipe; 14-gas distribution cavity; 15-second heat exchange pipe; 16-burner inlet; 17-first heat storage medium; 18-second heat storage medium. DETAILED DESCRIPTION

[0033] The present application is further described in detail below in combination with the drawings and specific embodiments. According to the following description, the advantages and characteristics of the present application will be more apparent.

[0034] Embodiment 1

[0035] Reference Figs. 1-2The application discloses a supercritical carbon dioxide auxiliary heating system for a solar thermal power station, and particularly applies to a tower type solar thermal power station.

[0036] The first heat storage medium heat exchanger 3 is communicated with an energy storage system of the solar thermal power station, and is filled with the first heat storage medium 17.

[0037] The auxiliary heater further comprises a burner 1 and a furnace 2, and the furnace 2 is provided with a burner inlet 16, and the burner 1 is communicated with the furnace 2 through the burner inlet 16.

[0038] The first heat exchange pipe 4 is filled with carbon dioxide, and passes through cavities of the first heat storage medium heat exchanger 3 and the furnace 2 in the direction of carbon dioxide flow, the first heat storage medium heat exchanger 3 is used for initial heating of the carbon dioxide, and the auxiliary heater is used for re-heating of the initially heated carbon dioxide.

[0039] The low-temperature carbon dioxide enters the first heat exchange pipe 4, the first heat exchange pipe 4 is in the first heat storage medium heat exchanger 3, and the heat storage medium solar salt in the heat storage system of the solar thermal power station is used for heating the low-temperature carbon dioxide. The solar salt in the solar thermal power station absorbs the heat of solar energy from a heat absorber, exchanges heat with the low-temperature carbon dioxide through the first heat storage medium heat exchanger 3, and the heat storage temperature of the current solar salt heat exchange system cannot reach the temperature requirement of the carbon dioxide power generation, the heat storage temperature of the tower type solar thermal power station is 565 DEG C, and the heat exchange temperature requirement of the supercritical carbon dioxide system cannot be met, therefore, the auxiliary heater is arranged in the direction of carbon dioxide flow in the embodiment, the carbon dioxide after the solar salt heat exchange re-enters the auxiliary heater for heating. High-temperature gas is generated in the burner 1 and the furnace 2, the high-temperature gas is used for heating the carbon dioxide in the first heat exchange pipe 4, and the heated carbon dioxide enters a subsequent power generation system.

[0040] The auxiliary heating system further comprises a second heat storage medium energy storage system, the second heat storage medium energy storage system comprises a plurality of heat storage tanks 5, the second heat storage medium 18 is filled in each heat storage tank 5, and the heat storage tank 5 is arranged in the furnace 2. The high-temperature gas is used for heating the carbon dioxide medium and the second heat storage medium 18 in the heat storage tank 5 at the same time, and the heat of the auxiliary heater is fully utilized.

[0041] The second heat storage medium 18 in the heat storage tank 5 is a high-temperature heat storage medium such as liquid metal, high-temperature molten salt (chloride salt, carbonate salt) and the like. Since the high-temperature heat storage medium has strong corrosiveness in an air atmosphere, the heat storage tank 5 is easily damaged, therefore, the second heat storage medium 18 is sealed and stored in the heat storage tank 5, and impurity gas in the heat storage tank 5 is exhausted.

[0042] In the case of the operation of the burner 1, the high-temperature gas as the main heat source heats the carbon dioxide in the first heat exchange pipe 4, and also heats the second heat storage medium in the heat storage tank 5; in the case of the non-operation of the burner 1, the heat energy stored in the heat storage tank 5 as the main heat source heats the carbon dioxide in the first heat exchange pipe 4.

[0043] In the direction of the carbon dioxide flow, the plurality of heat storage tanks 5 are arranged at intervals, the first heat exchange pipe 4 passes through the heat storage tank 5, and the part of the first heat exchange pipe 4 in contact with the heat storage tank 5 is the heated section, therefore, the heated sections of the first heat exchange pipe 4 are arranged at intervals relative to the second heat storage medium 18.

[0044] In the direction of the carbon dioxide flow, the heat storage tanks 5 are arranged at intervals, forming the interval heating of the carbon dioxide, which can make the heating amount of each heated section of the first heat exchange pipe 4 approximate, and the area between the interval heated sections can make the temperature of the carbon dioxide slowly transition. Thus, the carbon dioxide can relatively slowly transition from the liquid-like zone state to the gas-like zone in the heating process, avoiding the short-time temperature zone change when the supercritical carbon dioxide crosses the pseudo-critical line, causing the supercritical carbon dioxide physical property parameters to greatly fluctuate.

[0045] In the direction of the carbon dioxide flow, the interval distance between the adjacent heat storage tanks 5 gradually increases, that is, the interval between the heated sections of the first heat exchange pipe 4 gradually increases in the direction of the carbon dioxide flow, which can make the heating of the carbon dioxide in the first heat exchange pipe 4 more gentle, the principle is: ① when the burner 1 is used for combustion heating, the carbon dioxide entering the furnace 2 through the first heat exchange pipe 4 has a relatively large temperature difference with the combustion gas, the heat transfer efficiency is high, and rapid heating can be formed, but the heated sections are arranged at a relatively small interval, and the indirect heat transfer through the heat storage tank 5 (the high-temperature gas heats the second heat storage medium 18 in the heat storage tank 5, and the second heat storage medium 18 in the heat storage tank 5 exchanges heat with the carbon dioxide in the first heat exchange pipe 4) can prevent the continuous high-temperature heat transfer of the carbon dioxide, so that the carbon dioxide is slowly heated at intervals when it is at a relatively low temperature, avoiding the rapid change of the supercritical carbon dioxide temperature (rapid transition from the liquid-like zone state to the gas-like zone) causing the physical property to fluctuate dramatically; ② when the second heat storage medium 18 is used for heating, the carbon dioxide exchanges heat with the second heat storage medium 18 in the heat storage tank 5, and the temperature in the furnace 2 is relatively low, so that a heating and cooling interval heat exchange process is formed at this stage, if the distance between the adjacent heat storage tanks is small when the carbon dioxide just flows into the furnace, that is, the heating and cooling interval heat exchange process is relatively more in the downstream section of the carbon dioxide, a relatively gentle heating process of the carbon dioxide can be formed in the process of the carbon dioxide flow, avoiding the rapid change of the supercritical carbon dioxide temperature (rapid transition from the liquid-like zone state to the gas-like zone) causing the physical property to fluctuate dramatically.

[0046] The second heat storage medium energy storage system further comprises a liquid filling device 6, which is in communication with the heat storage tank 5 and is used to fill or discharge the second heat storage medium 18 in the heat storage tank 5.

[0047] The auxiliary heating system further comprises a flue gas treatment system, which comprises a compressor 10, a vortex chamber 11 and a second heat exchange pipe 15, the inlet of the compressor 10 is in communication with the flue gas outlet of the furnace 2, the outlet of the compressor 10 is in communication with the inlet of the vortex chamber 11, the high-temperature outlet of the vortex chamber 11 is in communication with one end of the hot flow pipe 12, the other end of the hot flow pipe 12 is in communication with the second heat exchange pipe 15 through the conveying pipe 7, and the low-temperature outlet of the vortex chamber 11 is in communication with the cold flow pipe 13.

[0048] The second heat storage medium energy storage system further comprises a heat exchange cavity 8, which is in communication with the heat storage tank 5 on one side and in communication with the liquid filling device 6 on the other side.

[0049] The second heat exchange pipe 15 is arranged inside the heat exchange cavity 8.

[0050] The high-temperature flue gas generated in the furnace 2 is converted into high-pressure flue gas in the compressor 10, the high-pressure flue gas enters the vortex chamber 11, and the secondary heated hot gas flows into the second heat exchange pipe 15, which is arranged in the heat exchange cavity 8, and the second heat exchange pipe 15 is surrounded by the second heat storage medium 18, the high-temperature flue gas in the second heat exchange pipe 15 heats the second heat storage medium 18 in the heat exchange cavity 8, and the low-temperature flue gas flowing out of the low-temperature outlet of the vortex chamber 11 flows out of the cold flow pipe. The heat exchange cavity 8 has the functions of heat exchange and heat storage, and also has the function of supplementing the second heat storage medium 18 in the heat storage tank 5.

[0051] The outer wall of the furnace 2 is provided with a ring channel 9, which is in communication with the upper part of the furnace 2.

[0052] The bottom of the ring channel 9 is in communication with the inlet of the compressor 10. The flue gas in the furnace 2 is transmitted to the outside of the furnace 2 through the ring channel 9, and the ring channel 9 is arranged around the side of the furnace 2 and can be used as a heat preservation layer of the furnace 2 to avoid heat loss.

[0053] The end of the hot flow pipe 12 close to the second heat exchange pipe 15 is in communication with a gas distribution cavity 14, the gas distribution cavity 14 is in communication with the second heat exchange pipe 15 through the conveying pipe 7, and the diameter of the gas distribution cavity 14 decreases from large to small along the direction of gas flow. The gas distribution cavity 14 with variable diameter is arranged in this way to generate a pressure gradient inside, so that the hot gas is uniformly distributed.

[0054] The low-temperature carbon dioxide enters the first heat storage medium heat exchanger 3 and exchanges heat with the first heat storage medium 17 in the heat storage system of the tower type solar thermal power station, and is heated to a range of 540-560℃.

[0055] The preliminarily heated carbon dioxide enters the auxiliary heater to be heated again to form supercritical carbon dioxide at 620℃ or above, and then enters the subsequent supercritical carbon dioxide power generation system.

[0056] The working principle of the auxiliary heater is as follows:

[0057] The burner 1 works to burn in the furnace 2, and the generated hot gas rises to flow through the first heat exchange pipe 4 and the outer wall area of the heat storage tank 5 to heat the carbon dioxide in the first heat exchange pipe 4, and then the heated carbon dioxide enters the subsequent power generation system; and the second heat storage medium 18 in the heat storage tank 5 is also heated to store heat energy.

[0058] The flue gas discharged from the annular channel 9 enters the compressor 10 to form high-pressure flue gas, and then the high-pressure flue gas generates a separation effect in the vortex chamber 11, and the cold gas flows out from the cold flow pipe, and the hot gas heated again flows out from the hot flow pipe 12; the hot gas enters the gas distribution cavity 14 through the hot flow pipe 12, and then enters the second heat exchange pipe 15 through the conveying pipe 7 to heat the second heat storage medium 18 in the heat exchange cavity 8 to store heat energy.

[0059] In the case that the burner 1 does not work, the supercritical carbon dioxide is heated by the heated second heat storage medium 18, and then enters the subsequent system.

[0060] Embodiment 2

[0061] A supercritical carbon dioxide power generation system for a solar thermal power station, comprising the supercritical carbon dioxide auxiliary heating system for a solar thermal power station of embodiment 1, and the carbon dioxide in the first heat exchange pipe 4 is heated by the auxiliary heater and then enters the turbine of the carbon dioxide power generation system to do work to generate power.

[0062] Embodiment 3

[0063] A solar thermal power generation system, comprising the supercritical carbon dioxide power generation system for a solar thermal power station of embodiment 2.

[0064] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above-described embodiments. Even if various changes are made to the present application, as long as the changes fall within the scope of the claims of the present application and the equivalent technology thereof, they still fall within the protection scope of the present application.

Claims

1. A supercritical carbon dioxide auxiliary heating system for a solar thermal power plant, characterized in that, include: The first heat storage medium heat exchanger is connected to the heat storage system of the solar thermal power plant; An auxiliary heater, further comprising a burner and a furnace, wherein the burner is in communication with the furnace; The first heat exchange tube is filled with carbon dioxide. Along the direction of carbon dioxide flow, the first heat exchange tube passes through the cavity of the first heat storage medium heat exchanger and the furnace. The first heat storage medium heat exchanger is used for initial heating of carbon dioxide, and the auxiliary heater is used for reheating the initially heated carbon dioxide. The auxiliary heating system also includes a second thermal storage medium energy storage system, which includes a plurality of thermal storage tanks. A second thermal storage medium is introduced into each of the thermal storage tanks, and the thermal storage tanks are disposed inside the furnace. The first heat exchange tube passes through the heat storage tank; the heat storage tanks are arranged at intervals along the direction of carbon dioxide flow; the distance between adjacent heat storage tanks increases from small to large. The auxiliary heating system also includes a flue gas treatment system, which includes a compressor, a vortex chamber, a heat flow tube, and a second heat exchange tube. The inlet of the compressor is connected to the flue gas outlet of the furnace, the outlet of the compressor is connected to the inlet of the vortex chamber, the high-temperature outlet of the vortex chamber is connected to the heat flow tube, and the heat flow tube is connected to the second heat exchange tube through a delivery pipe. The second thermal energy storage system further includes a heat exchange chamber, which is connected to the thermal storage tank, and the second heat exchange tube is disposed inside the heat exchange chamber; the outer wall of the furnace is provided with a ring channel, which is connected to the upper part of the furnace and the bottom of the ring channel is connected to the inlet of the compressor.

2. The supercritical carbon dioxide auxiliary heating system for a solar thermal power plant according to claim 1, characterized in that, The second thermal energy storage system also includes a filling device, which is connected to the thermal storage tank.

3. The supercritical carbon dioxide auxiliary heating system for a solar thermal power plant according to claim 2, characterized in that, The heat exchange chamber is connected to the liquid filling device.

4. The supercritical carbon dioxide auxiliary heating system for a solar thermal power plant according to claim 1, characterized in that, The end of the heat flow tube near the second heat exchange tube is connected to the gas distribution chamber. The gas distribution chamber is connected to the second heat exchange tube through the delivery pipe. Along the direction of gas flow, the diameter of the gas distribution chamber decreases from large to small.

5. A supercritical carbon dioxide power generation system for a solar thermal power plant, characterized in that, Includes the supercritical carbon dioxide auxiliary heating system for solar thermal power plants as described in any one of claims 1-4.

6. A solar thermal power generation system, characterized in that, Includes the supercritical carbon dioxide power generation system for solar thermal power plants as described in claim 5.

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