A reheat steam split coal-fired power generation system coupled with heat storage and operation method

Abstract

The present invention relates to the technical field of coal-fired power generation systems, and provides a reheated steam split coal-fired power generation system coupled with heat storage and an operating method. The reheated steam split coal-fired power generation system coupled with heat storage comprises: a coal-fired power generation system; a pre-installed steam turbine connected to a boiler in the coal-fired power generation system; and a heat storage system connected to both the pre-installed steam turbine and the coal-fired power generation system. The heat storage system is capable of storing thermal energy from reheated steam in the boiler when the coal-fired power generation system is operating at high load, and is capable of releasing thermal energy to heat the outlet steam of the pre-installed steam turbine when the coal-fired power generation system is operating at low load. The coal-fired power generation system, by configuring the heat storage system, uses reheated steam from the boiler in the coal-fired power generation system to charge the heat storage system, and uses the stored thermal energy to heat the outlet steam of the pre-installed steam turbine, thereby increasing the temperature of the steam entering the high-pressure cylinder of the coal-fired power generation system, thereby keeping the outlet steam temperature of the high-pressure cylinder within a reasonable range.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired power generation systems, and in particular to a reheat steam split-flow coal-fired power generation system coupled with heat storage and an operation method thereof. Background Art

[0002] With the development of renewable energy, the proportion of renewable energy power generation is also increasing. Due to the unstable shortcomings of renewable energy, the integration of renewable energy power generation into the power grid poses a threat to the stability of the power grid. Therefore, it is necessary to use power plants for peak load regulation to improve the stability of the power grid. However, during the deep peak load regulation of the power plant, the operating conditions of the power plant deviate significantly from the design conditions, resulting in a significant decrease in the efficiency of the unit, which reduces the economic efficiency of the unit. The problem of significantly reduced unit efficiency at low load can be solved by configuring a pre-steam turbine; however, because the main steam first performs work in the pre-steam turbine before entering the high-pressure cylinder, the outlet steam temperature of the high-pressure cylinder is too low, posing a threat to the safe operation of the high-pressure cylinder. Increasing the outlet steam temperature of the high-pressure cylinder requires energy consumption. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is that after a pre-turbine is configured in the unit in the prior art, the main steam first performs work in the pre-turbine before entering the high-pressure cylinder, resulting in the outlet steam temperature of the high-pressure cylinder being too low, posing a threat to the safe operation of the high-pressure cylinder. Increasing the outlet steam temperature of the high-pressure cylinder requires energy consumption, thereby providing a reheat steam split coal-fired power generation system coupled with heat storage and an operation method.

[0004] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0005] A reheated steam split coal-fired power generation system coupled with heat storage comprises: a coal-fired power generation system; a pre-installed steam turbine connected to a boiler in the coal-fired power generation system; and a heat storage system connected to both the pre-installed steam turbine and the coal-fired power generation system, wherein the heat storage system is capable of storing the heat energy of the reheated steam in the boiler when the coal-fired power generation system is operating at high load, and is capable of releasing the heat energy to heat the outlet steam of the pre-installed steam turbine when the coal-fired power generation system is operating at low load.

[0006] Furthermore, the coal-fired power generation system includes a connected boiler, a high-pressure cylinder and a medium- and low-pressure cylinder; the inlet of the pre-turbine is connected to the main steam outlet of the boiler, and the outlet of the pre-turbine is connected to the inlet of the high-pressure cylinder; the heat storage system includes a steam-molten salt heat exchanger, a low-temperature molten salt heat storage tank and a high-temperature molten salt heat storage tank; the steam inlet of the steam-molten salt heat exchanger is connected to the outlet of the pre-turbine and the reheat steam outlet of the boiler, and the steam outlet of the steam-molten salt heat exchanger is connected to the inlet of the high-pressure cylinder and the first steam extraction port of the medium- and low-pressure cylinders; the molten salt inlet of the steam-molten salt heat exchanger is connected to the low-temperature molten salt heat storage tank, and the molten salt outlet of the steam-molten salt heat exchanger is connected to the high-temperature molten salt heat storage tank; wherein a first control valve is provided on the pipeline between the outlet of the pre-turbine and the steam inlet of the steam-molten salt heat exchanger; a second control valve is provided on the pipeline between the inlet of the high-pressure cylinder and the steam outlet of the steam-molten salt heat exchanger; A third control valve is provided on the pipeline between the main steam outlet of the boiler and the inlet of the pre-steam turbine; a fourth control valve is provided on the pipeline between the outlet of the pre-steam turbine and the inlet of the high-pressure cylinder; a fifth control valve is provided on the pipeline between the main steam outlet of the boiler and the inlet of the high-pressure cylinder; a sixth control valve is provided on the pipeline between the reheat steam outlet of the boiler and the steam inlet of the steam-molten salt heat exchanger; a seventh control valve is provided on the pipeline between the steam outlet of the steam-molten salt heat exchanger and the first steam extraction port of the intermediate and low-pressure cylinders; an eighth control valve is provided on the pipeline between the inlet of the low-temperature molten salt heat storage tank and the steam-molten salt heat exchanger; a ninth control valve is provided on the pipeline between the outlet of the low-temperature molten salt heat storage tank and the steam-molten salt heat exchanger; a tenth control valve is provided on the pipeline between the inlet of the high-temperature molten salt heat storage tank and the steam-molten salt heat exchanger; and an eleventh control valve is provided on the pipeline between the outlet of the high-temperature molten salt heat storage tank and the steam-molten salt heat exchanger.

[0007] Furthermore, a first pump body is provided on the pipeline between the ninth control valve and the outlet of the low-temperature molten salt heat storage tank; a second pump body is provided on the pipeline between the eleventh control valve and the outlet of the high-temperature molten salt heat storage tank.

[0008] Furthermore, the reheat steam split coal-fired power generation system coupled with heat storage also includes a first generator adapted to be arranged with the pre-installed steam turbine.

[0009] Furthermore, the coal-fired power generation system also includes a second generator, a condenser, a low-pressure heater group, a deaerator, a feed water pump and a high-pressure heater group; the second generator is adapted to the high-pressure cylinder and the medium and low-pressure cylinder settings; the inlet of the condenser is connected to the steam outlet of the medium and low-pressure cylinders, and the outlet of the condenser is connected to the feed water inlet of the low-pressure heater group; the feed water outlet of the low-pressure heater group is connected to the feed water inlet of the deaerator; the feed water outlet of the deaerator is connected to the inlet of the feed water pump; the outlet of the feed water pump is connected to the feed water inlet of the high-pressure heater group; the feed water outlet of the high-pressure heater group is connected to the feed water inlet of the boiler; the steam inlet of the low-pressure heater group is connected to the first steam extraction port of the medium and low-pressure cylinders; the steam inlet of the deaerator is connected to the second steam extraction port of the medium and low-pressure cylinders; the steam inlet of the high-pressure heater group is connected to the steam extraction port of the high-pressure cylinder.

[0010] A method for operating a reheated steam split coal-fired power generation system coupled with heat storage includes the above-mentioned reheated steam split coal-fired power generation system. The specific operating method is as follows: when the system is operating at high load, a portion of the heat in the reheated steam generated by the boiler of the coal-fired power generation system is stored in the heat storage system; when the system is operating at medium or low load, the heat stored in the heat storage system is used to heat the outlet steam of the front steam turbine.

[0011] Furthermore, when the system is operating at high load, storing a portion of the heat in the reheated steam generated by the boiler of the coal-fired power generation system in the heat storage system specifically includes: closing the first control valve, the second control valve, the eighth control valve and the eleventh control valve, and opening the fifth control valve, the sixth control valve, the seventh control valve, the ninth control valve, the tenth control valve and the first pump body, so that a portion of the reheated steam generated by the boiler enters the steam side of the steam-molten salt heat exchanger, heating the low-temperature molten salt entering the steam-molten salt heat exchanger from the low-temperature molten salt heat storage tank, and storing the heated high-temperature molten salt in the high-temperature molten salt heat storage tank.

[0012] Furthermore, the steam side flow of the steam-molten salt heat exchanger is adjusted by the sixth control valve to adjust the load of the system; the molten salt flow of the steam-molten salt heat exchanger is adjusted by the ninth control valve and the tenth control valve to make the temperature of the high-temperature molten salt entering the high-temperature molten salt heat storage tank reach the design value.

[0013] Furthermore, if the pre-turbine is in the startup state, the third control valve and the fourth control valve are opened.

[0014] Furthermore, when the system is operating at medium or low load, using the heat stored in the heat storage system to heat the outlet steam of the pre-turbine specifically includes: closing the fourth control valve, the sixth control valve, the seventh control valve, the ninth control valve and the tenth control valve, opening the first control valve, the second control valve, the third control valve, the fifth control valve, the eighth control valve, the eleventh control valve and the second pump body, and using the high-temperature molten salt from the high-temperature molten salt heat storage tank to heat the outlet steam of the pre-turbine.

[0015] Furthermore, the molten salt flow rate of the steam-molten salt heat exchanger is regulated by the eighth control valve and the eleventh control valve so that the outlet steam temperature of the high-pressure cylinder is higher than the lower limit value.

[0016] Furthermore, if the outlet steam temperature of the high-pressure cylinder is higher than the lower limit by more than 30° C., the fifth control valve is closed.

[0017] Furthermore, if the molten salt reserves in the high-temperature molten salt heat storage tank are insufficient, the first control valve, the second control valve, the eighth control valve, the eleventh control valve and the second pump body are closed; the fourth control valve is opened, and the third control valve is adjusted down.

[0018] Furthermore, the steam side design temperature of the steam-molten salt heat exchanger is the rated reheat steam temperature, and the design flow rate is 40%-60% of the rated main steam flow rate; the molten salt side design temperature of the steam-molten salt heat exchanger is the rated temperature of the high-temperature molten salt heat storage tank, and the design flow rate is 40%-60% of the steam side design flow rate.

[0019] The technical solution of the present invention has the following advantages:

[0020] The reheated steam split coal-fired power generation system coupled with heat storage provided by the present invention, by configuring a heat storage system, uses the reheated steam of the boiler in the coal-fired power generation system to charge the heat storage system, and uses the stored heat energy to heat the outlet steam of the front steam turbine, thereby increasing the temperature of the steam entering the high-pressure cylinder of the coal-fired power generation system, thereby keeping the outlet steam temperature of the high-pressure cylinder within a reasonable range, avoiding threats to the safe operation of the high-pressure cylinder, and eliminating the need to consume energy outside the system to heat the outlet steam of the high-pressure cylinder, thereby reducing the energy consumption of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1Schematic diagram of a reheat steam split coal-fired power generation system coupled with heat storage in an embodiment of the present invention.

[0023] 1. Boiler; 2. High-pressure cylinder; 3. Medium- and low-pressure cylinders; 4. First generator; 5. Condenser; 6. Low-pressure heater group; 7. Deaerator; 8. Feedwater pump; 9. High-pressure heater group; 10. Pre-turbine; 11. Second generator; 12. First control valve; 13. Second control valve; 14. Third control valve; 15. Fourth control valve; 16. Fifth control valve; 17. Steam-molten salt heat exchanger; 18. Sixth control valve; 19. Seventh control valve; 20. Eighth control valve; 21. Ninth control valve; 22. Tenth control valve; 23. Eleventh control valve; 24. First pump body; 25. Second pump body; 26. Low-temperature molten salt heat storage tank; 27. High-temperature molten salt heat storage tank. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Figure 1Schematic diagram of a reheat steam split coal-fired power generation system coupled with heat storage in an embodiment of the present invention, as shown in FIG. Figure 1 As shown, this embodiment provides a reheat steam split coal-fired power generation system coupled with heat storage, comprising: a coal-fired power generation system; a pre-installed steam turbine 10 connected to a boiler 1 in the coal-fired power generation system; and a heat storage system connected to both the pre-installed turbine and the coal-fired power generation system. The heat storage system is capable of storing the heat energy of the reheated steam in the boiler 1 when the coal-fired power generation system is operating at high load, and is capable of releasing the heat energy to heat the outlet steam of the pre-installed steam turbine 10 when the coal-fired power generation system is operating at low load.

[0029] The reheated steam split coal-fired power generation system coupled with heat storage provided in this embodiment is configured with a heat storage system. The reheated steam from the boiler 1 in the coal-fired power generation system is used to charge the heat storage system, and the stored heat energy is used to heat the outlet steam of the pre-turbine 10. This increases the temperature of the steam entering the high-pressure cylinder 2 of the coal-fired power generation system, thereby keeping the outlet steam temperature of the high-pressure cylinder 2 within a reasonable range, avoiding threats to the safe operation of the high-pressure cylinder 2. It also eliminates the need to consume energy outside the system to heat the outlet steam of the high-pressure cylinder 2, thereby reducing the energy consumption of the entire system.

[0030] Furthermore, the coal-fired power generation system includes a connected boiler 1, a high-pressure cylinder 2, and intermediate- and low-pressure cylinders 3. The inlet of the pre-turbine 10 is connected to the main steam outlet of the boiler 1, and the outlet of the pre-turbine 10 is connected to the inlet of the high-pressure cylinder 2. The heat storage system includes a steam-molten salt heat exchanger 17, a low-temperature molten salt heat storage tank 26, and a high-temperature molten salt heat storage tank 27. The steam inlet of the steam-molten salt heat exchanger 17 is connected to the outlet of the pre-turbine 10 and the reheat steam outlet of the boiler 1, while the steam outlet of the steam-molten salt heat exchanger 17 is connected to the inlet of the high-pressure cylinder 2 and the first steam extraction port of the intermediate- and low-pressure cylinders 3. The molten salt inlet of the steam-molten salt heat exchanger 17 is connected to the low-temperature molten salt heat storage tank 26, and the molten salt outlet of the steam-molten salt heat exchanger 17 is connected to the high-temperature molten salt heat storage tank 27. A first control valve 12 is provided in the pipeline between the outlet of the pre-turbine 10 and the steam inlet of the steam-molten salt heat exchanger 17. A second control valve 13 is installed on the pipeline between the inlet of the high-pressure cylinder 2 and the steam outlet of the steam-molten salt heat exchanger 17. A third control valve 14 is installed on the pipeline between the main steam outlet of the boiler 1 and the inlet of the pre-turbine 10. A fourth control valve 15 is installed on the pipeline between the outlet of the pre-turbine 10 and the inlet of the high-pressure cylinder 2. A fifth control valve 16 is installed on the pipeline between the main steam outlet of the boiler 1 and the inlet of the high-pressure cylinder 2. A sixth control valve 18 is installed on the pipeline between the reheat steam outlet of the boiler 1 and the steam inlet of the steam-molten salt heat exchanger 17. A seventh control valve 19 is installed on the pipeline between the steam outlet of the steam-molten salt heat exchanger 17 and the first steam extraction port of the intermediate and low-pressure cylinders 3. An eighth control valve 20 is installed on the pipeline between the inlet of the low-temperature molten salt heat storage tank 26 and the steam-molten salt heat exchanger 17. A ninth control valve 21 is installed on the pipeline between the outlet of the low-temperature molten salt heat storage tank 26 and the steam-molten salt heat exchanger 17. A tenth control valve 22 is provided on the pipeline between the inlet of the high-temperature molten salt heat storage tank 27 and the steam-molten salt heat exchanger 17. An eleventh control valve 23 is provided on the pipeline between the outlet of the high-temperature molten salt heat storage tank 27 and the steam-molten salt heat exchanger 17.

[0031] Furthermore, a first pump body 24 is provided on the pipeline between the ninth control valve 21 and the outlet of the low-temperature molten salt heat storage tank 26 ; a second pump body 25 is provided on the pipeline between the eleventh control valve 23 and the outlet of the high-temperature molten salt heat storage tank 27 .

[0032] Furthermore, the reheat steam split coal-fired power generation system coupled with heat storage also includes a first generator 4 adapted to be provided with the pre-installed steam turbine 10 .

[0033] Furthermore, the coal-fired power generation system also includes a second generator 11, a condenser 5, a low-pressure heater group 6, a deaerator 7, a feedwater pump 8, and a high-pressure heater group 9. The second generator 11 is adapted to be installed in the high-pressure cylinder 2 and the intermediate and low-pressure cylinders 3; the inlet of the condenser 5 is connected to the steam outlet of the intermediate and low-pressure cylinders 3, and the outlet of the condenser 5 is connected to the feedwater inlet of the low-pressure heater group 6. The feedwater outlet of the low-pressure heater group 6 is connected to the feedwater inlet of the deaerator 7; the feedwater outlet of the deaerator 7 is connected to the inlet of the feedwater pump 8. The outlet of the feedwater pump 8 is connected to the feedwater inlet of the high-pressure heater group 9; the feedwater outlet of the high-pressure heater group 9 is connected to the feedwater inlet of the boiler 1. The steam inlet of the low-pressure heater group 6 is connected to the first steam extraction port of the intermediate and low-pressure cylinders 3; the steam inlet of the deaerator 7 is connected to the second steam extraction port of the intermediate and low-pressure cylinders 3; and the steam inlet of the high-pressure heater group 9 is connected to the steam extraction port of the high-pressure cylinder 2.

[0034] Specifically, in the coupled heat storage reheat steam diversion coal-fired power generation system, a branch of the main steam outlet of the boiler 1 is connected to the inlet of the high-pressure cylinder 2 through the fifth control valve 16. The steam outlet of the high-pressure cylinder 2 is connected to the reheat steam inlet of the boiler 1, and the reheat steam outlet of the boiler 1 is connected to the inlet of the medium and low-pressure cylinders 3. The steam outlet of the medium and low-pressure cylinders 3 is connected to the inlet of the condenser 5, and the outlet of the condenser 5 is connected to the feed water inlet of the low-pressure heater group 6. The feed water outlet of the low-pressure heater group 6 is connected to the feed water inlet of the deaerator 7. The feed water outlet of the deaerator 7 is connected to the inlet of the feed water pump 8. The outlet of the feed water pump 8 is connected to the feed water inlet of the high-pressure heater group 9, and the feed water outlet of the high-pressure heater group 9 is connected to the feed water inlet of the boiler 1. The steam inlets of the low-pressure heater group 6, the deaerator 7 and the high-pressure heater group 9 are respectively connected to the first steam extraction port, the second steam extraction port of the medium and low-pressure cylinders 3 and the steam extraction port of the high-pressure cylinder 2. The shafts of the high-pressure cylinder 2 and the medium and low-pressure cylinders 3 are connected, and are also connected to the shaft of the second generator 11.

[0035] Another branch of the main steam outlet of boiler 1 connects to the inlet of pre-turbine 10 through third control valve 14. The outlet of pre-turbine 10 is connected to the inlet of first control valve 12. The outlet of first control valve 12 is connected to the steam inlet of steam-molten salt heat exchanger 17. The steam outlet of steam-molten salt heat exchanger 17 is connected to the inlet of second control valve 13. The outlet of second control valve 13 merges with the outlet of fifth control valve 16 and is connected to the inlet of high-pressure cylinder 2. The steam inlet of steam-molten salt heat exchanger 17 also passes through sixth control valve 18 and is connected to the reheat steam outlet of boiler 1. The steam outlet of steam-molten salt heat exchanger 17 also passes through seventh control valve 19 and is connected to the steam inlet of low-pressure heater group 6. The outlet of pre-turbine 10 is also connected to the inlet of high-pressure cylinder 2 through fourth control valve 15.

[0036] The outlet of the low-temperature molten salt heat storage tank 26 is connected to the inlet of the first pump body 24, which is in turn connected to the ninth control valve 21. The ninth control valve 21 is connected to the molten salt inlet of the steam-molten salt heat exchanger 17 and, via the eighth control valve 20, to the inlet of the low-temperature molten salt heat storage tank 26. The outlet of the high-temperature molten salt heat storage tank 27 is connected to the inlet of the second pump body 25, which is, in turn, connected to the inlet of the eleventh control valve 23. The outlet of the eleventh control valve 23 is connected to the molten salt outlet of the steam-molten salt heat exchanger 17 and, via the tenth control valve 22, to the inlet of the high-temperature molten salt heat storage tank 27.

[0037] Another embodiment provides an operating method for a coupled heat storage reheated steam split coal-fired power generation system, including the above-mentioned coupled heat storage reheated steam split coal-fired power generation system, and the specific operating method is as follows: when the system is operating at high load, a portion of the heat in the reheated steam generated by the boiler 1 of the coal-fired power generation system is stored in the heat storage system; when the system is operating at medium and low loads, the heat stored in the heat storage system is used to heat the outlet steam of the front steam turbine 10.

[0038] Furthermore, when the system is operating at high load, storing a portion of the heat in the reheated steam generated by the boiler 1 of the coal-fired power generation system in the heat storage system specifically includes: closing the first control valve 12, the second control valve 13, the eighth control valve 20 and the eleventh control valve 23, and opening the fifth control valve 16, the sixth control valve 18, the seventh control valve 19, the ninth control valve 21, the tenth control valve 22 and the first pump body 24, so that a portion of the reheated steam generated by the boiler 1 enters the steam side of the steam-molten salt heat exchanger 17, heats the low-temperature molten salt entering the steam-molten salt heat exchanger 17 from the low-temperature molten salt heat storage tank 26, and stores the heated high-temperature molten salt in the high-temperature molten salt heat storage tank 27.

[0039] Furthermore, the steam side flow of the steam-molten salt heat exchanger 17 is adjusted by the sixth control valve 18 to adjust the load of the system; the molten salt flow of the steam-molten salt heat exchanger 17 is adjusted by the ninth control valve 21 and the tenth control valve 22 to make the temperature of the high-temperature molten salt entering the high-temperature molten salt heat storage tank 27 reach the design value.

[0040] Furthermore, if the pre-turbine 10 is in the startup state, the third control valve 14 and the fourth control valve 15 are opened.

[0041] Furthermore, when the system is operating at medium or low load, using the heat stored in the heat storage system to heat the outlet steam of the pre-turbine 10 specifically includes: closing the fourth control valve 15, the sixth control valve 18, the seventh control valve 19, the ninth control valve 21 and the tenth control valve 22, and opening the first control valve 12, the second control valve 13, the third control valve 14, the fifth control valve 16, the eighth control valve 20, the eleventh control valve 23 and the second pump body 25, and using the high-temperature molten salt from the high-temperature molten salt heat storage tank 27 to heat the outlet steam of the pre-turbine 10.

[0042] Furthermore, the molten salt flow rate of the steam-molten salt heat exchanger 17 is adjusted by the eighth control valve 20 and the eleventh control valve 23 so that the outlet steam temperature of the high-pressure cylinder 2 is higher than the lower limit value.

[0043] Furthermore, if the outlet steam temperature of the high-pressure cylinder 2 is higher than the lower limit by more than 30° C., the fifth control valve 16 is closed.

[0044] Furthermore, if the molten salt reserves in the high-temperature molten salt heat storage tank 27 are insufficient, the first control valve 12, the second control valve 13, the eighth control valve 20, the eleventh control valve 23 and the second pump body 25 are closed; the fourth control valve 15 is opened, and the third control valve 14 is adjusted down.

[0045] Furthermore, the steam side design temperature of the steam-molten salt heat exchanger 17 is the rated reheat steam temperature, and the design flow rate is 40%-60% of the rated main steam flow rate; the molten salt side design temperature of the steam-molten salt heat exchanger 17 is the rated temperature of the high-temperature molten salt heat storage tank 27, and the design flow rate is 40%-60% of the steam side design flow rate.

[0046] Specifically, this coupled thermal storage and reheat steam shunt coal-fired power generation system operates by charging the high-temperature molten salt heat storage tank 27 when the system is under high load. The first and second control valves 12 and 13 are closed, eliminating the path between the pre-turbine 10 and the steam-molten salt heat exchanger 17. The eighth and eleventh control valves 20 and 23 are closed, placing the thermal storage system in a charging state. The fifth, sixth, seventh, and tenth control valves 16, 18, 19, 21, and 22, along with the first pump 24, are opened. Reheated steam from the boiler 1 partially enters the steam side of the steam-molten salt heat exchanger 17, while low-temperature molten salt from the low-temperature molten salt heat storage tank 26 enters the molten salt side of the steam-molten salt heat exchanger 17, where the reheated steam heats the low-temperature molten salt. The steam-side flow rate of the steam-molten salt heat exchanger 17 is used to regulate the system load within a certain range. The molten salt flow rate at the steam-molten salt heat exchanger 17 is controlled to ensure that the molten salt temperature entering the high-temperature molten salt heat storage tank 27 reaches the designed value. Throughout this process, if the pre-turbine 10 is in the startup state, the third control valve 14 and the fourth control valve 15 are opened. This is because at high loads, the pre-turbine 10 is shut down. Even if it is in the startup state, the steam flow entering the pre-turbine 10 is low, which will not cause a significant drop in the outlet steam temperature of the high-pressure cylinder 2. Therefore, there is no need to heat the outlet steam of the pre-turbine 10. Simultaneously, during this stage, the energy of some of the reheated steam generated by the boiler 1 is stored.

[0047] When the system is at medium to low load, the high-temperature molten salt heat storage tank 27 begins discharging energy. At this time, the pre-turbine 10 is in the startup state, and the steam flow rate of the pre-turbine 10 is 40% to 60% of the main steam flow rate generated by the boiler 1. At this time, the fourth control valve 15, the sixth control valve 18, the seventh control valve 19, the ninth control valve 21, and the tenth control valve 22 are closed, stopping the energy storage process in the high-temperature molten salt heat storage tank 27. The first control valve 12, the second control valve 13, the third control valve 14, and the fifth control valve 16 are then opened, allowing a portion of the main steam generated by the boiler 1 to enter the pre-turbine 10 and the outlet steam from the pre-turbine 10 to enter the steam-molten salt heat exchanger 17. Simultaneously, the eighth control valve 20, the eleventh control valve 23, and the second pump 25 are opened, allowing the high-temperature molten salt from the high-temperature molten salt heat storage tank 27 to heat the outlet steam from the pre-turbine 10. The molten salt flow rate on the steam-molten salt heat exchanger 17 side is controlled to ensure that the outlet steam temperature of the high-pressure cylinder 2 is above the lower limit. If the steam flow rate entering the pre-steam turbine 10 increases, the required flow rate of high-temperature molten salt will also increase. Since the fifth control valve 16 is not completely closed, the main steam pressure at the outlet of the boiler 1 is maintained at the design value. If the outlet steam temperature of the high-pressure cylinder 2 is more than 30°C higher than the lower limit, the fifth control valve 16 is closed, and the main steam pressure at the outlet of the boiler 1 no longer maintains the design value, but changes proportionally with the flow rate. This is because the higher the steam flow rate entering the pre-steam turbine 10, the higher the efficiency of the pre-steam turbine 10, but the lower the steam temperature entering the high-pressure cylinder 2. Therefore, if the outlet steam temperature of the high-pressure cylinder 2 is high enough, the flow rate of the pre-steam turbine 10 can be increased. If the main steam generated by the boiler 1 completely enters the pre-steam turbine 10, the main steam pressure of the boiler 1 cannot be maintained at the set value, but will change according to the steam flow rate. If the molten salt storage tank 27 is insufficient, the first control valve 12, second control valve 13, eighth control valve 20, eleventh control valve 23, and second pump 25 are closed, the fourth control valve 15 is opened, and the third control valve 14 is adjusted downward. Because insufficient molten salt storage tank 27 can't heat the outlet steam flow of the pre-turbine 10, the flow of the pre-turbine 10 should be reduced by adjusting the third control valve 14, and the power of the system should be controlled by adjusting the fifth control valve 16.

[0048] In summary, the coupled heat storage reheat steam diversion coal-fired power generation system and operation method in the present application can heat the outlet steam of the front steam turbine 10 with high-temperature molten salt, thereby increasing the outlet steam temperature of the high-pressure cylinder 2; by formulating the system's operation strategy at different loads, it can ensure that the reserves of high-temperature molten salt are sufficient, so that the front steam turbine 10 and the high-pressure cylinder 2 can operate efficiently and safely under all working conditions.

[0049] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A reheat steam split coal-fired power generation system coupled with heat storage, characterized in that: include: Coal-fired power generation system, including connected boilers, high-pressure cylinders, and medium- and low-pressure cylinders; a pre-mounted steam turbine, wherein the inlet of the pre-mounted steam turbine is connected to the main steam outlet of the boiler, and the outlet of the pre-mounted steam turbine is connected to the inlet of the high-pressure cylinder; a heat storage system connected to both the pre-installed steam turbine and the coal-fired power generation system, wherein the heat storage system is capable of storing the heat energy of the reheated steam in the boiler when the coal-fired power generation system is operating at high load, and is capable of releasing the heat energy to heat the outlet steam of the pre-installed steam turbine when the coal-fired power generation system is operating at low load.

2. The reheat steam split coal-fired power generation system coupled with heat storage according to claim 1 is characterized in that: The heat storage system includes a steam-molten salt heat exchanger, a low-temperature molten salt heat storage tank and a high-temperature molten salt heat storage tank; The steam inlet of the steam-molten salt heat exchanger is connected to the outlet of the front steam turbine and the reheat steam outlet of the boiler, and the steam outlet of the steam-molten salt heat exchanger is connected to the inlet of the high-pressure cylinder and the first steam extraction port of the medium and low-pressure cylinders; the molten salt inlet of the steam-molten salt heat exchanger is connected to the low-temperature molten salt heat storage tank, and the molten salt outlet of the steam-molten salt heat exchanger is connected to the high-temperature molten salt heat storage tank; Wherein, a first control valve is provided on the pipeline between the outlet of the pre-turbine and the steam inlet of the steam-molten salt heat exchanger; A second control valve is provided on the pipeline between the inlet of the high-pressure cylinder and the steam outlet of the steam-molten salt heat exchanger; A third control valve is provided on the pipeline between the main steam outlet of the boiler and the inlet of the pre-turbine; A fourth control valve is provided on the pipeline between the outlet of the pre-turbine and the inlet of the high-pressure cylinder; A fifth control valve is provided on the pipeline between the main steam outlet of the boiler and the inlet of the high-pressure cylinder; A sixth control valve is provided on the pipeline between the reheat steam outlet of the boiler and the steam inlet of the steam-molten salt heat exchanger; A seventh control valve is provided on the pipeline between the steam outlet of the steam-molten salt heat exchanger and the first steam extraction port of the medium and low pressure cylinder; An eighth control valve is provided on the pipeline between the inlet of the low-temperature molten salt heat storage tank and the steam-molten salt heat exchanger; A ninth control valve is provided on the pipeline between the outlet of the low-temperature molten salt heat storage tank and the steam-molten salt heat exchanger; A tenth control valve is provided on the pipeline between the inlet of the high-temperature molten salt heat storage tank and the steam-molten salt heat exchanger; An eleventh control valve is provided on the pipeline between the outlet of the high-temperature molten salt heat storage tank and the steam-molten salt heat exchanger.

3. The reheat steam split coal-fired power generation system coupled with heat storage according to claim 2 is characterized in that: A first pump body is provided on the pipeline between the ninth control valve and the outlet of the low-temperature molten salt heat storage tank; A second pump body is provided on the pipeline between the eleventh control valve and the outlet of the high-temperature molten salt heat storage tank.

4. The reheat steam split coal-fired power generation system coupled with heat storage according to claim 1 is characterized in that: It also includes a first generator adapted to be arranged with the front steam turbine.

5. The reheat steam split coal-fired power generation system coupled with heat storage according to any one of claims 2 to 4, characterized in that: The coal-fired power generation system further includes a second generator, a condenser, a low-pressure heater group, a deaerator, a feedwater pump, and a high-pressure heater group; The second generator is adapted to be arranged in the high-pressure cylinder and the medium- and low-pressure cylinders; The inlet of the condenser is connected to the steam outlet of the medium and low pressure cylinders, and the outlet of the condenser is connected to the water inlet of the low pressure heater group; The water feed outlet of the low-pressure heater group is connected to the water feed inlet of the deaerator; The water feed outlet of the deaerator is connected to the inlet of the water feed pump; The outlet of the water supply pump is connected to the water supply inlet of the high-pressure heater group; The feed water outlet of the high-pressure heater group is connected to the feed water inlet of the boiler; The steam inlet of the low-pressure heater group is connected to the first steam extraction port of the medium and low-pressure cylinders; The steam inlet of the deaerator is connected to the second steam extraction port of the medium and low pressure cylinder; The steam inlet of the high-pressure heater group is connected to the steam extraction port of the high-pressure cylinder.

6. A method for operating a reheat steam split coal-fired power generation system coupled with heat storage, characterized in that: The reheat steam split coal-fired power generation system coupled with heat storage according to any one of claims 1 to 5 has the following specific operating method: When the system is operating at high load, a portion of the heat in the reheated steam generated by the boiler of the coal-fired power generation system is stored in the heat storage system; When the system is operating at medium or low load, the heat stored in the heat storage system is used to heat the outlet steam of the front steam turbine.

7. The method for operating a reheat steam split coal-fired power generation system coupled with heat storage according to claim 6, characterized in that: When the system is operating at high load, part of the heat in the reheated steam generated by the boiler of the coal-fired power generation system is stored in the heat storage system, specifically including: Close the first control valve, the second control valve, the eighth control valve and the eleventh control valve, and open the fifth control valve, the sixth control valve, the seventh control valve, the ninth control valve, the tenth control valve and the first pump body, so that a portion of the reheated steam generated by the boiler enters the steam side of the steam-molten salt heat exchanger, heats the low-temperature molten salt entering the steam-molten salt heat exchanger from the low-temperature molten salt heat storage tank, and stores the heated high-temperature molten salt in the high-temperature molten salt heat storage tank.

8. The method for operating a reheat steam split coal-fired power generation system coupled with heat storage according to claim 7, characterized in that: The steam side flow of the steam-molten salt heat exchanger is adjusted by the sixth control valve to adjust the load of the system; The molten salt flow rate of the steam-molten salt heat exchanger is regulated by the ninth control valve and the tenth control valve so that the temperature of the high-temperature molten salt entering the high-temperature molten salt heat storage tank reaches the design value.

9. The method for operating a reheat steam split coal-fired power generation system coupled with heat storage according to claim 7, characterized in that: If the pre-turbine is in the startup state, the third control valve and the fourth control valve are opened.

10. The method for operating a reheat steam split coal-fired power generation system coupled with heat storage according to claim 6, characterized in that: When the system is running at medium or low load, the heat stored in the heat storage system is used to heat the outlet steam of the front steam turbine, specifically including: Close the fourth control valve, sixth control valve, seventh control valve, ninth control valve and tenth control valve, open the first control valve, second control valve, third control valve, fifth control valve, eighth control valve, eleventh control valve and second pump body, and use the high-temperature molten salt from the high-temperature molten salt heat storage tank to heat the outlet steam of the front steam turbine.

11. The method for operating a reheat steam split coal-fired power generation system coupled with heat storage according to claim 10, characterized in that: The molten salt flow rate of the steam-molten salt heat exchanger is adjusted by the eighth control valve and the eleventh control valve to make the outlet steam temperature of the high-pressure cylinder higher than the lower limit value.

12. The method for operating a reheat steam split coal-fired power generation system coupled with heat storage according to claim 10, characterized in that: If the outlet steam temperature of the high-pressure cylinder is higher than the lower limit by more than 30°C, the fifth control valve will be closed.

13. The method for operating a reheat steam split coal-fired power generation system coupled with heat storage according to claim 10, characterized in that: If the molten salt reserves in the high-temperature molten salt heat storage tank are insufficient, the first control valve, the second control valve, the eighth control valve, the eleventh control valve and the second pump body are closed; Open the fourth control valve and reduce the third control valve.

14. The method for operating a reheat steam split coal-fired power generation system coupled with thermal storage according to any one of claims 6 to 13, characterized in that: The steam side design temperature of the steam-molten salt heat exchanger is the rated reheat steam temperature, and the design flow rate is 40%-60% of the rated main steam flow rate; The design temperature of the molten salt side of the steam-molten salt heat exchanger is the rated temperature of the high-temperature molten salt heat storage tank, and the design flow rate is 40%-60% of the design flow rate of the steam side.

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