A thermal power generation system with supercritical carbon dioxide and steam dual working fluid circulation

Abstract

A thermal power generation system with a supercritical carbon dioxide and steam dual working medium cycle includes a steam power generation system and a boiler, and also includes a supercritical carbon dioxide power generation system; the water outlet of the high-pressure heater of the steam power generation system is connected to the inlet of the economizer of the boiler, the outlet of the superheater of the boiler is connected to the inlet of the high-pressure cylinder of the steam turbine of the steam power generation system; the primary gas outlet of the final superheater of the boiler is connected to the inlet of the high-pressure turbine of the supercritical carbon dioxide power generation system, the secondary gas outlet of the final reheater of the boiler is connected to the inlet of the low-pressure turbine of the supercritical carbon dioxide power generation system, the secondary gas inlet of the low-temperature reheater of the boiler is connected to the primary gas outlet of the high-pressure turbine, and the gas supply outlet of the high-temperature reheater of the supercritical carbon dioxide is connected to the air inlet of the low-temperature superheater of the boiler. The present invention improves energy utilization efficiency and can realize the cascade utilization of heat generated by fuel combustion.

Description

Technical Field

[0001] The invention relates to a power generation system, in particular to a thermal power generation system with supercritical carbon dioxide and steam dual working medium circulation. Background Art

[0002] The traditional thermal power generation system based on the steam Rankine cycle is mature and stable, and the boiler has a high utilization rate of the heat released by fuel combustion. However, under the existing parameters and material technology level, it is difficult to further improve the efficiency of steam power generation due to the limitations of the Rankine cycle configuration. The new power cycle with supercritical carbon dioxide as the working fluid can achieve higher power generation efficiency while maintaining the same working fluid parameters as the steam cycle because the working fluid properties match the cycle characteristics well. However, there are problems such as difficulty in utilizing boiler waste heat and low utilization rate of heat released by fuel combustion.

[0003] In summary, the above system, when used alone as a power generation system, has the disadvantages of low energy utilization efficiency and the heat generated by fuel combustion cannot be effectively utilized. Summary of the invention

[0004] The present invention aims to overcome the deficiencies of the prior art and provides a thermal power generation system with a dual working medium cycle of supercritical carbon dioxide and steam.

[0005] A thermal power generation system with a supercritical carbon dioxide and steam dual-working medium cycle comprises a steam power generation system and a boiler, and also comprises a supercritical carbon dioxide power generation system; the water outlet of the high-pressure heater of the steam power generation system is connected to the inlet of the economizer of the boiler, the outlet of the superheater of the boiler is connected to the inlet of the high-pressure cylinder of the steam turbine of the steam power generation system; the primary gas outlet of the final superheater of the boiler is connected to the inlet of the high-pressure turbine of the supercritical carbon dioxide power generation system, the secondary gas outlet of the final reheater of the boiler is connected to the inlet of the low-pressure turbine of the supercritical carbon dioxide power generation system, the secondary gas inlet of the low-temperature reheater of the boiler is connected to the primary gas outlet of the high-pressure turbine, and the air supply outlet of the high-temperature reheater of the supercritical carbon dioxide is connected to the air inlet of the low-temperature superheater of the boiler.

[0006] Compared with the prior art, the present invention has the following beneficial effects:

[0007] The supercritical carbon dioxide and steam dual-fluid cycle power generation system established by the present invention shares a boiler as a heat source. The boiler design suitable for dual-fluid cycle is simultaneously arranged with water working fluid and supercritical carbon dioxide heating surface. After the two working fluids are heated to the rated parameters, they enter their respective power generation systems to generate electricity. The present invention can realize the cascade utilization of heat generated by fuel combustion, and further improve the energy utilization efficiency by utilizing the respective characteristics of the two cycles. The system can be newly built or, from the perspective of saving equipment investment, utilize the equipment and facilities of existing units to transform, directly saving water treatment equipment and steam turbine generator equipment investment.

[0008] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of a thermal power generation system according to Embodiment 1 of the present invention;

[0010] Figure 2 This is a schematic diagram of a thermal power generation system according to Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0011] Specific implementation method 1: Combination Figure 1-Figure 2 Description: A thermal power generation system with a supercritical carbon dioxide and steam dual-fluid cycle in this embodiment includes a steam power generation system C and a boiler E, and also includes a supercritical carbon dioxide power generation system D; the water outlet of the high-pressure heater 18 of the steam power generation system C is connected to the economizer inlet of the boiler E, and the outlet of the superheater of the boiler is connected to the inlet of the high-pressure cylinder 13 of the steam turbine of the steam power generation system; the primary gas outlet of the final superheater of the boiler E is connected to the inlet of the high-pressure turbine 20 of the supercritical carbon dioxide power generation system D, the secondary gas outlet of the final reheater of the boiler E is connected to the inlet of the low-pressure turbine 21 of the supercritical carbon dioxide power generation system D, the secondary gas inlet of the low-temperature reheater of the boiler E is connected to the primary gas outlet of the high-pressure turbine 20, and the air supply outlet of the high-temperature reheater 25 of the supercritical carbon dioxide power generation system D is connected to the air inlet of the low-temperature superheater of the boiler E.

[0012] Furthermore, if Figure 1-Figure 2 As shown, the generator 27 of the supercritical carbon dioxide power generation system D is connected to the high-pressure turbine 20, the high-pressure turbine 20 is connected to the low-pressure turbine 21, the low-pressure turbine 21 is connected to the re-compressor 22, the re-compressor 22 is connected to the main compressor 24, the main compressor 24 is connected to the cooler 23, the low-pressure turbine 21 is connected to the high-temperature regenerator 25, and the cooler 23 is connected to the low-temperature regenerator 26.

[0013] This implementation mode combines the characteristics of high efficiency of supercritical carbon dioxide in the high parameter area and high efficiency of steam power generation in the low parameter area, and designs a supercritical carbon dioxide and steam dual-working fluid cycle power generation scheme to achieve the coupling of steam power generation Rankine cycle and supercritical carbon dioxide power generation Brayton cycle. On the one hand, it solves the difficulties in designing large-capacity supercritical carbon dioxide boilers under existing technical conditions and reduces the amount of expensive metal materials used in boilers. At the same time, by selectively arranging supercritical carbon dioxide high-efficiency heat transfer heating surfaces in the boiler, it greatly reduces the heating resistance loss of supercritical carbon dioxide and improves the efficiency of the Brayton cycle. On the other hand, steam boilers can still be used to effectively utilize exhaust waste heat to make up for this deficiency in supercritical carbon dioxide power generation systems.

[0014] Typically, the generator C19 of the steam power generation system C is connected to the low-pressure cylinder 14, the turbine low-pressure cylinder 14 is connected to the turbine high-pressure cylinder 13, the turbine high-pressure cylinder 13 is connected to the high-pressure heater 18, the high-pressure heater 18 is connected to the deaerator 17, the deaerator 17 is connected to the high-pressure heater 18 through the feed water pump 28, the deaerator 17 is connected to the low-pressure heater 16, the condenser 15 is connected to the low-pressure heater 16, and at the same time, the condenser 15 is connected to the low-pressure heater 16 through the condensate pump 29.

[0015] Based on the above content, the technical solution of the present invention is further described below with examples:

[0016] Example 1: The supercritical carbon dioxide power generation system D is a single reheat system, and the water-based steam power generation system C is a non-reheat system. The two systems share a π-type boiler. Figure 1 shown.

[0017] The boiler comprises a front flue economizer A1, a rear flue economizer A2, a front flue superheater A3, a rear flue superheater A4, a furnace inner wall superheater A5, a low temperature reheater A7, a low temperature superheater A6, a partition screen superheater A8, a screen superheater A9, a final stage reheater A10 and a final stage superheater A11;

[0018] The water outlet of the high-pressure heater 18 of the steam power generation system is respectively connected to the inlet of the front flue economizer A1 and the rear flue economizer A2 of the boiler, and the outlets of the front flue economizer A1 and the rear flue economizer A2 are respectively connected to the front flue superheater A3 and the rear flue superheater A4 through the boiler furnace water-cooled wall, and the steam outlets of the front flue superheater A3 and the rear flue superheater A4 are respectively connected to the high-pressure cylinder 13 of the steam turbine of the steam power generation system through the furnace inner wall superheater A5, and the outlets of the low-temperature reheater A6 and the low-temperature superheater A7 are respectively connected to the final stage reheater A10 and the partition screen superheater A 8 is connected, the partition plate superheater A8 is connected to the plate superheater A9, the plate superheater A9 is connected to the final superheater A11, the primary gas outlet of the final superheater A11 is connected to the inlet of the high-pressure turbine 20 of the supercritical carbon dioxide power generation system, the secondary gas outlet of the final reheater A10 is connected to the inlet of the low-pressure turbine 21 of the supercritical carbon dioxide power generation system, the air supply outlet of the high-temperature reheater 25 of the supercritical carbon dioxide is connected to the air inlet of the low-temperature superheater A7 of the boiler, and the secondary gas inlet of the low-temperature reheater A6 of the boiler is connected to the secondary gas outlet of the high-pressure turbine 20.

[0019] For the water working medium flow: after the boiler feed water is preheated by the parallel front flue economizer A1 and the rear flue economizer A2, the undersaturated water enters the boiler water-cooled wall for phase change and becomes slightly superheated steam, and then enters the parallel front flue superheater A3 and the rear flue superheater A4 to be heated into superheated steam, and then enters the high-pressure cylinder 13 of the steam turbine to do work after the superheat is further increased by the furnace inner wall superheater A5. There is an exhaust port in the middle of the cylinder body of the high-pressure cylinder 13 of the steam turbine to extract part of the steam and enter the shell side of the high-pressure heater 18 to heat the feed water, and the remaining small part of the exhaust steam enters the deaerator 17, and most of it enters the low-pressure cylinder 14 of the steam turbine to continue to do work. Before leaving the low-pressure cylinder 14 of the steam turbine, part of the steam is extracted and enters the shell side of the low-pressure heater 16 to heat the condensed water, and the rest enters the condenser 15 to condense into water. After the condensate is pressurized by the condensate pump 29, it passes through the low-pressure heater 16 tube side and the deaerator 17 in sequence, and is further pressurized by the feed water pump 28 and heated by the high-pressure heater 18 tube side before returning to the boiler.

[0020] For the supercritical carbon dioxide process: the boiler feed gas is preliminarily heated by the low-temperature superheater A6, and then further heated by the partition screen superheater A8 and screen superheater A9, and finally heated to the rated temperature of the primary gas outlet in the final superheater A11; the primary gas outlet gas flow passes through the high-pressure turbine 20 to do work, and the exhaust enters the reheating process. The cold reheated gas passes through the low-temperature reheater A7 for preliminarily heating, and then passes through the final reheater A10 to the required rated secondary gas flow temperature and enters the low-pressure turbine 21 to do work. The exhaust gas of the low-pressure turbine 21 passes through the high-temperature reheater 25 and the low-temperature reheater 26 in turn to heat the feed gas and then is divided into two gas flows. One gas flow is directly boosted by the recompressor 22 and merged into the intermediate feed gas of the two-stage reheater, and the other gas flow passes through the cooler 23 and enters the main compressor 24 for boosting. The boosted feed gas passes through the two-stage reheater and is heated before returning to the boiler.

[0021] Example 2: The supercritical carbon dioxide power generation system D is a single reheat system, and the water-based steam power generation system C is a non-reheat system. The two systems share a tower-type boiler, as shown in the attached figure. Figure 2 shown.

[0022] The boiler comprises a secondary superheater B1, a final reheater B2, a final superheater B3, a low-temperature superheater B4, a low-temperature reheater B5, a front flue superheater B6, a rear flue superheater B7, a front flue economizer B8 and a rear flue economizer B9;

[0023] The outlet of the secondary superheater B1 is connected to the inlet of the final superheater B3, the outlet of the low-temperature superheater B4 is connected to the inlet of the secondary superheater B1, the inlet of the final reheater B2 is connected to the outlet of the low-temperature reheater B5, the outlets of the front flue superheater B6 and the rear flue superheater B7 are respectively connected to the inlet of the high-pressure cylinder 13 of the steam turbine of the steam power generation system, the water outlet of the high-pressure heater 18 of the steam power generation system is respectively connected to the inlet of the front flue economizer B8 and the rear flue economizer B9 of the boiler, the front flue economizer B 8 and the outlet of the rear flue economizer B9 are connected to the cold water wall of the boiler furnace, the air supply outlet of the high-temperature reheater 25 of the supercritical carbon dioxide is connected to the air inlet of the low-temperature superheater B4 of the boiler, the primary gas outlet of the final superheater B3 is connected to the inlet of the high-pressure turbine 20 of the supercritical carbon dioxide power generation system, the secondary gas outlet of the final reheater B2 is connected to the inlet of the low-pressure turbine 21 of the supercritical carbon dioxide power generation system, and the secondary gas inlet of the low-temperature reheater B5 of the boiler is connected to the secondary gas outlet of the high-pressure turbine 20.

[0024] For the water working medium flow: after the boiler feed water is preheated by the parallel front flue economizer B8 and the rear flue economizer B9, the undersaturated water enters the boiler water-cooled wall for phase change and becomes slightly superheated steam, and then enters the parallel front flue superheater B6 and the rear flue superheater B7 to be heated into superheated steam and output to the turbine high-pressure cylinder 13. There is an air extraction port in the middle of the cylinder body of the turbine high-pressure cylinder 13 to extract part of the steam and enter the high-pressure heater 18 shell side to heat the feed water, and the remaining small part of the exhaust steam flow enters the deaerator 17 and most of it enters the turbine low-pressure cylinder 14 to continue to work. Before leaving, the steam entering the turbine low-pressure cylinder 15 is partially extracted and enters the low-pressure heater 16 shell side to heat the condensate, and the rest enters the condenser 15 to condense into water. After the condensate is pressurized by the condensate pump 29, it passes through the low-pressure heater 16 tube side and the deaerator 17 in turn, and then further pressurized by the feed water pump 28 and heated by the high-pressure heater 18 tube side to return to the boiler.

[0025] For the supercritical carbon dioxide process: the boiler feed gas is preliminarily heated by the low-temperature superheater B4, then further heated by the secondary superheater B1, and finally heated to the rated temperature of the primary gas in the final superheater B3; the primary gas outlet airflow passes through the high-pressure turbine 20 to do work, and the exhaust enters the reheating process. The cold reheated gas passes through the low-temperature reheater B5 for preliminarily heating, and then is heated to the required rated secondary gas parameters by the final reheater B2. After the low-pressure turbine 21 completes the work, the exhaust gas at the boiler outlet passes through the high-temperature reheater 25 and the low-temperature reheater 26 in turn to heat the feed gas and is divided into two airflows. One airflow is directly boosted by the recompressor 22 and merged into the middle feed gas of the two-stage reheater, and the other airflow passes through the cooler 23 and enters the main compressor 24 for boosting. The boosted feed gas is heated by the two-stage reheater and then returns to the boiler.

[0026] Theoretical studies have shown that when the working fluid temperature is higher than 450°C, the supercritical carbon dioxide Brayton power generation cycle has a higher efficiency advantage than the steam Rankine cycle at higher parameters. The supercritical carbon dioxide and steam dual-working fluid cycle power generation system established in this embodiment shares a boiler as a heat source. The boiler design suitable for dual-working fluid circulation is simultaneously arranged with water working fluid and supercritical carbon dioxide heating surfaces. After the two working fluids are heated to the rated parameters, they enter their respective power generation systems to generate electricity. This implementation method can realize the cascade utilization of heat generated by fuel combustion, and further improve energy utilization efficiency by utilizing the respective characteristics of the two cycles. The system can be newly built or, from the perspective of saving equipment investment, utilize the equipment and facilities of existing units to transform and directly save water treatment equipment and steam turbine generator equipment investment.

[0027] The dual-fluid coupling power generation system proposed in this embodiment uses the core equipment of traditional thermal power generation - the boiler as a common heat source. Water working fluid and supercritical carbon dioxide heating surface are arranged simultaneously on a conventional boiler burning hydrocarbon fuels. The water-cooled wall of the furnace can directly apply the mature steam boiler selection guidelines (using conventional vertical tube ring membrane wall or lower furnace spiral tube ring and upper furnace vertical tube ring), solving the difficulty of furnace selection. The rear flue of the boiler also adopts steam cooling wall, avoiding the problem of using supercritical carbon dioxide as the wall cooling working fluid with large pressure loss and small temperature rise, which has a great impact on the efficiency of the supercritical carbon dioxide Brayton cycle. Supercritical carbon dioxide chooses to use the screen-type heating surface above the furnace and the horizontal flue, which has the advantages of high heat transfer efficiency and low resistance. This embodiment can simultaneously realize high-parameter steam power generation and supercritical carbon dioxide power generation system in parallel.

[0028] The present invention has been disclosed as above with preferred implementation cases, but it is not used to limit the present invention. Any technician familiar with the profession can make slight changes or modifications to equivalent implementation cases with equivalent changes by using the above-disclosed structures and technical contents without departing from the scope of the technical solution of the present invention, which still fall within the scope of the technical solution of the present invention.

Claims

1. A thermal power generation system with supercritical carbon dioxide and steam dual working medium circulation, comprising a steam power generation system C and a boiler E, characterized in that: It also includes a supercritical carbon dioxide power generation system D; The water outlet of the high-pressure heater of the steam power generation system C is connected to the inlet of the economizer of the boiler E, and the outlet of the superheater of the boiler E is connected to the inlet of the high-pressure cylinder of the steam turbine of the steam power generation system; the primary gas outlet of the final superheater of the boiler E is connected to the inlet of the high-pressure turbine of the supercritical carbon dioxide power generation system, the secondary gas outlet of the final reheater of the boiler E is connected to the inlet of the low-pressure turbine of the supercritical carbon dioxide power generation system, the secondary gas inlet of the low-temperature reheater A (6) of the boiler E is connected to the primary gas outlet of the high-pressure turbine (20), and the high-temperature of the supercritical carbon dioxide is connected to the primary gas outlet of the high-pressure turbine (21). The air supply outlet of the regenerator (25) is connected to the air inlet of the low-temperature superheater of the boiler E; the generator (27) of the supercritical carbon dioxide power generation system D is connected to the high-pressure turbine (20), the high-pressure turbine (20) is connected to the low-pressure turbine (21), the low-pressure turbine (21) is connected to the recompressor (22), the recompressor (22) is connected to the main compressor (24), the main compressor (24) is connected to the cooler (23), the low-pressure turbine (21) is connected to the high-temperature regenerator (25), and the cooler (23) is connected to the low-temperature regenerator (26); The boiler is a π-type boiler, comprising a front flue economizer A (1), a rear flue economizer A (2), a front flue superheater A (3), a rear flue superheater A (4), a furnace wall superheater A (5), a low-temperature reheater A (6), a low-temperature superheater A (7), a partition screen superheater A (8), a screen superheater A (9), a final reheater A (10) and a final superheater A (11); steam power generation The water outlet of the high-pressure heater (18) of the system is connected to the inlet of the front flue economizer A (1) and the rear flue economizer A (2) of the boiler respectively. The outlets of the front flue economizer A (1) and the rear flue economizer A (2) are connected to the front flue superheater A (3) and the rear flue superheater A (4) respectively through the boiler furnace water-cooled wall. The steam outlets of the front flue superheater A (3) and the rear flue superheater A (4) are connected to the boiler furnace water-cooled wall respectively. The heat exchanger A (5) is connected to the high-pressure cylinder (13) of the steam turbine of the steam power generation system. The outlets of the low-temperature reheater A (6) and the low-temperature superheater A (7) are respectively connected to the final-stage reheater A (10) and the partition-plate superheater A (8). The partition-plate superheater A (8) is connected to the platen superheater A (9). The platen superheater A (9) is connected to the final-stage superheater A (11). The primary gas outlet of the final-stage superheater A (11) is connected to the inlet of the high-pressure turbine (20) of the supercritical carbon dioxide power generation system. The secondary gas outlet of the final-stage reheater A (10) is connected to the inlet of the low-pressure turbine (21) of the supercritical carbon dioxide power generation system. The air supply outlet of the high-temperature reheater (25) of the supercritical carbon dioxide is connected to the air inlet of the low-temperature superheater A (7) of the boiler. The secondary gas inlet of the low-temperature reheater A (6) of the boiler is connected to the primary gas outlet of the high-pressure turbine (20).

2. A thermal power generation system with supercritical carbon dioxide and steam dual working medium circulation, comprising a steam power generation system C and a boiler E, characterized in that: It also includes a supercritical carbon dioxide power generation system D; The water outlet of the high-pressure heater of the steam power generation system C is connected to the inlet of the economizer of the boiler E, and the outlet of the superheater of the boiler E is connected to the inlet of the high-pressure cylinder of the steam turbine of the steam power generation system; the primary gas outlet of the final superheater of the boiler E is connected to the inlet of the high-pressure turbine of the supercritical carbon dioxide power generation system, the secondary gas outlet of the final reheater of the boiler E is connected to the inlet of the low-pressure turbine of the supercritical carbon dioxide power generation system, the secondary gas inlet of the low-temperature reheater B (5) of the boiler E is connected to the primary gas outlet of the high-pressure turbine (20), and the high-temperature of the supercritical carbon dioxide is connected to the primary gas outlet of the high-pressure turbine (21). The air supply outlet of the regenerator (25) is connected to the air inlet of the low-temperature superheater of the boiler E; the generator (27) of the supercritical carbon dioxide power generation system D is connected to the high-pressure turbine (20), the high-pressure turbine (20) is connected to the low-pressure turbine (21), the low-pressure turbine (21) is connected to the recompressor (22), the recompressor (22) is connected to the main compressor (24), the main compressor (24) is connected to the cooler (23), the low-pressure turbine (21) is connected to the high-temperature regenerator (25), and the cooler (23) is connected to the low-temperature regenerator (26); The boiler is a tower-type boiler, comprising a secondary superheater B (1), a final reheater B (2), a final superheater B (3), a low-temperature superheater B (4), a low-temperature reheater B (5), a front flue superheater B (6), a rear flue superheater B (7), a front flue economizer B (8) and a rear flue economizer B (9); the outlet of the secondary superheater B (1) is connected to the inlet of the final superheater B (3), the outlet of the low-temperature superheater B (4) is connected to the inlet of the secondary superheater B (1), the inlet of the final reheater B (2) is connected to the outlet of the low-temperature reheater B (5), the outlets of the front flue superheater B (6) and the rear flue superheater B (7) are respectively connected to the inlet of the high-pressure cylinder (13) of the steam turbine of the steam power generation system, and the steam The water outlet of the high-pressure heater (18) of the power generation system is respectively connected to the inlet of the front flue economizer B (8) and the rear flue economizer B (9) of the boiler, the outlet of the front flue economizer B (8) and the rear flue economizer B (9) are connected to the water-cooled wall of the boiler furnace, the air supply outlet of the high-temperature reheater (25) of the supercritical carbon dioxide is connected to the air inlet of the low-temperature superheater B (4) of the boiler, the primary gas outlet of the final superheater B (3) is connected to the inlet of the high-pressure turbine (20) of the supercritical carbon dioxide power generation system, the secondary gas outlet of the final reheater B (2) is connected to the inlet of the low-pressure turbine (21) of the supercritical carbon dioxide power generation system, and the secondary gas inlet of the low-temperature reheater B (5) of the boiler is connected to the primary gas outlet of the high-pressure turbine (20).

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