Fused salt energy storage coupled coal-fired power generation system with deep peak shaving and rapid peak topping

Abstract

The utility model relates to the field of fused salt energy storage, specifically relates to a fused salt energy storage coupling coal-fired power generation system with depth peak shaving and fast peak topping, which comprises: a boiler, a steam turbine generator unit, a boiler feedwater system, a fused salt heat storage unit and a fused salt heat release unit; the fused salt heat storage unit is used to improve the depth peak shaving capacity of the coal power unit; the fused salt heat release unit is used to release the heat storage of high-temperature fused salt to realize fast peak topping of the coal power unit; when the unit needs depth peak shaving, part of the hot reheat steam and the intermediate stage extraction steam in the high-pressure cylinder are extracted to heat the low-temperature fused salt in multiple stages in series and store it in the high-temperature fused salt tank, so as to realize load pressure reduction of the generator unit; when the unit needs fast peak topping, the heat storage released by the high-temperature fused salt stored in the high-temperature fused salt tank is used to heat the boiler feedwater to quickly improve the work output of the steam turbine, so that more electric energy is sent to the grid to meet the peak demand of the power grid.

Description

Technical Field

[0001] This utility model relates to the field of molten salt energy storage, specifically to a molten salt energy storage coupled with coal-fired power generation system that features deep peak shaving and rapid peak shaving. Background Technology

[0002] As the proportion of new energy power generation such as wind and solar power in the power grid increases, their inherent intermittency and volatility pose unprecedented challenges to the safe and stable operation of the power grid. In order to maintain the real-time balance of the power grid, traditional coal-fired power generating units, as the main power source in the power system, are required to undertake more frequent and in-depth flexible operation tasks such as peak shaving and frequency regulation.

[0003] However, conventional coal-fired power generating units are typically designed to operate stably near rated load to achieve maximum power generation efficiency. When units are required to operate for extended periods under low load conditions (i.e., deep peak shaving) or to respond quickly to load increase commands (rapid peaking), they often face a series of technical challenges.

[0004] Molten salt energy storage has significant advantages such as large thermal storage capacity and long cycle, high energy density, long service life, and low investment and operating costs. Molten salt energy storage coupled with coal-fired power units can greatly improve the peak-shaving, frequency regulation, and peak-load capacity of coal-fired power units, and is one of the most effective and feasible technical approaches to realize the flexible transformation of coal-fired power units.

[0005] Currently, extensive technical research and industrial demonstration applications are underway, indicating a huge future market potential. Molten salt thermal storage commonly employs either electric or steam heating methods, each with its own advantages and disadvantages. Electric heating systems are simpler, less technically demanding, and offer greater operational flexibility, allowing for larger peak-shaving ranges in coal-fired power units and the generation of higher molten salt temperatures. It has been adopted by most demonstration projects, but its main drawback is lower thermal efficiency. Steam heating, on the other hand, boasts high thermal efficiency and eliminates the need for costly power supply and distribution systems. However, the system is more complex and technically challenging, resulting in fewer engineering applications using steam heating and indicating that the technology is still immature. Further in-depth technical research and development are urgently needed for steam heating.

[0006] The simplest, most economical, and most efficient technical route for utilizing thermal energy in the molten salt exothermic process is to generate steam for direct external supply or to heat the return water of the heating system for external heating. However, there are not many power plants in China with such application scenarios. Most coal-fired power units do not have a long-term and stable demand for external gas or heat supply in their vicinity. How to efficiently utilize the exothermic heat of molten salt is a technical problem that urgently needs to be solved. In summary, the best solution is to reuse all the heat from the molten salt exothermic process in the steam-water system of the coal-fired power unit for peak power generation. Utility Model Content

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a molten salt energy storage coupled with coal-fired power generation system that features deep peak shaving and rapid peak shaving. This effectively enhances the deep peak shaving and rapid peak shaving capabilities of coal-fired power generating units, improves their operational flexibility, and further expands the application scenarios of molten salt exothermics. When the coal-fired power generating unit requires deep peak shaving, steam is drawn from the high-pressure cylinder and the hot reheat steam header to heat the molten salt, thereby reducing the amount of steam entering the turbine to perform work and thus reducing the unit's power generation. When the coal-fired power generating unit requires peak shaving, the heat released by the high-temperature molten salt exothermics is used to heat the boiler feedwater, thereby reducing the amount of steam consumed by the high-pressure heater group to heat the boiler feedwater. This reduces the need for the high-pressure heater group to draw steam from the high-pressure and intermediate-pressure cylinders for heating, thus significantly improving the turbine's power output and load ramp-up rate.

[0008] This utility model is achieved through the following technical solution:

[0009] A molten salt energy storage coupled coal-fired power generation system with deep peak shaving and rapid peak shaving includes: a boiler, a steam turbine generator set, a boiler feedwater system, a molten salt thermal storage unit, and a molten salt heat release unit;

[0010] The main steam outlet and hot reheat steam outlet of the boiler are respectively connected to the steam inlet of the turbine generator set; the exhaust steam outlet of the turbine generator set is connected to the boiler feedwater system, and the outlet of the boiler feedwater system is connected to the inlet of the boiler.

[0011] The molten salt thermal storage unit is connected to the steam turbine generator set and the boiler through the first and second extraction steam pipelines. It extracts steam from the corresponding parts to heat the molten salt for thermal storage, thereby improving the deep peak-shaving capacity of the coal-fired power unit.

[0012] The molten salt exothermic unit heats the boiler feedwater by releasing the stored heat of high-temperature molten salt to achieve rapid peak power generation for coal-fired power units.

[0013] Optionally, the steam turbine generator set includes a steam turbine and a generator, and the steam turbine further includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder;

[0014] The main steam and hot reheat steam generated by the boiler are respectively delivered to the steam inlets of the high-pressure cylinder and the intermediate-pressure cylinder;

[0015] The first extraction steam pipeline extracts a portion of the hot reheat steam from the hot reheat steam header between the boiler outlet and the intermediate pressure cylinder inlet.

[0016] The second extraction pipeline extracts a portion of the steam from the intermediate stage of the high-pressure cylinder;

[0017] Optionally, the boiler feedwater system includes a condenser, a condensate pump, a low-pressure heater group, a deaerator, a boiler feedwater pump, and a high-pressure heater group connected in series via pipelines.

[0018] The condenser condenses the exhaust steam from the low-pressure cylinder into water;

[0019] The low-pressure heater group consists of multiple heaters connected in series, and steam is drawn from different parts of the low-pressure cylinder as heating steam to heat the condensate in stages.

[0020] The deaerator draws steam from the intermediate-pressure cylinder as its heating steam to remove dissolved oxygen and other non-condensable gases from the boiler feedwater.

[0021] The boiler feedwater pump draws water from the deaerator, pressurizes it, heats it through the high-pressure heater group, and then sends it into the boiler.

[0022] The high-pressure heater group consists of multiple heaters connected in series, which draw steam from the intermediate-pressure cylinder and the high-pressure cylinder respectively to heat the boiler feedwater in stages.

[0023] Optionally, the molten salt thermal storage unit includes a low-temperature molten salt tank, a high-temperature molten salt tank, a molten salt heater, and a low-temperature molten salt pump;

[0024] The outlet of the cryogenic molten salt tank is connected to the molten salt inlet of the molten salt heater via the cryogenic molten salt pump; the molten salt outlet of the molten salt heater is connected to the inlet of the high-temperature molten salt tank.

[0025] The hot reheat steam extracted by the first extraction steam pipeline and part of the steam extracted from the intermediate stage of the high-pressure cylinder by the second extraction steam pipeline are respectively delivered to the molten salt heater to heat the molten salt flowing out of the low-temperature molten salt tank in stages.

[0026] Optionally, the molten salt heater includes a first heat exchanger, a second heat exchanger, and a third heat exchanger;

[0027] The steam inlet of the third heat exchanger is connected to the first extraction steam pipeline, the steam outlet of the third heat exchanger is connected to the steam inlet of the first heat exchanger, and the steam condensate outlet of the first heat exchanger is connected to the deaerator of the boiler feedwater system.

[0028] The steam inlet of the second heat exchanger is connected to the second extraction steam pipeline, and the slightly superheated steam from the steam outlet of the second heat exchanger flows into the cold reheat steam header and is connected to the boiler.

[0029] Optionally, both the third heat exchanger and the second heat exchanger use only the sensible heat of steam to heat the molten salt, while the first heat exchanger uses the remaining sensible heat and latent heat after steam heat exchange to heat the molten salt.

[0030] Optionally, the molten salt heat release unit includes a high-temperature molten salt pump and a feedwater heater. The inlet of the high-temperature molten salt pump is connected to the outlet of the high-temperature molten salt tank, and the outlet of the feedwater heater is connected to the inlet of the low-temperature molten salt tank. The high-temperature molten salt pump delivers high-temperature molten salt to the feedwater heater, where the heat released by the high-temperature molten salt heat release is used to heat part of the boiler feedwater.

[0031] Optionally, the feedwater heater is connected to the high-pressure heater group bypass. When the coal-fired power unit needs peak power, the feedwater heater is put into operation. The boiler feedwater from the boiler feedwater pump flows through the high-pressure heater group and the feedwater heater respectively for heating before converging and entering the boiler. The distribution ratio of boiler feedwater flow into the feedwater heater can be flexibly adjusted according to the peak power grid requirements.

[0032] Optionally, the molten salt operating temperature range is 160~450℃.

[0033] Alternatively, the molten salt may be a ternary molten salt or another molten salt.

[0034] This invention addresses the need for deep peak shaving in coal-fired power units. The system extracts a portion of the steam from the turbine's steam cycle to heat low-temperature molten salt in a multi-stage series connection, storing the heated salt in a high-temperature molten salt tank. This reduces the load on the generator unit. When the coal-fired power unit needs rapid peak shaving, the system utilizes the stored high-temperature molten salt in the tank, releasing its heat through a molten salt heat release unit to heat the boiler feedwater, thereby rapidly increasing the turbine's power output.

[0035] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0036] 1) Molten salt thermal storage is carried out by combining high-pressure cylinder extraction steam with hot reheat steam extraction. All the heat released by the molten salt is efficiently fed into the boiler feedwater system of the coal-fired power unit for reuse. This technical route has outstanding advantages such as high thermal efficiency, good peak regulation and frequency regulation and peak performance, fast response speed and wide application.

[0037] 2) The heat source for molten salt thermal storage is partly taken from the high-pressure cylinder extraction steam, that is, the medium-pressure steam after the high-pressure main steam has done a certain amount of work in the high-pressure cylinder, instead of directly taking steam from the main steam. This can significantly reduce the steam pressure entering the molten salt energy storage system, thereby reducing the design pressure and cost of the steam pipeline and heat exchange tube bundle of the molten salt thermal storage unit, which is conducive to improving the safety of the molten salt energy storage system. On the other hand, it can make the most of the energy of the high-pressure part of the main steam to do more work. Attached Figure Description

[0038] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention, and are included in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0039] Figure 1 This is a schematic diagram of the structure of the molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving, according to the present invention.

[0040] Figure 2 This is a schematic diagram of the molten salt heat storage process of the system according to the present invention.

[0041] Figure 3 This is a schematic diagram of the molten salt exothermic process of the system according to this utility model.

[0042] Reference numerals: 1. Boiler; 2. Steam turbine generator set; 201. High-pressure cylinder; 202. Intermediate-pressure cylinder; 203. Low-pressure cylinder; 204. Generator; 3. Condenser; 4. Condensate pump; 5. Low-pressure heater assembly; 6. Deaerator; 7. Boiler feedwater pump; 8. High-pressure heater assembly; 9. Low-temperature molten salt tank; 10. Low-temperature molten salt pump; 11. First heat exchanger; 12. Second heat exchanger; 13. Third heat exchanger; 14. High-temperature molten salt tank; 15. High-temperature molten salt pump; 16. Feedwater heater. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this utility model.

[0044] It should also be noted that, for ease of description, only the parts related to this utility model are shown in the accompanying drawings.

[0045] Where there is no conflict, the embodiments and features of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] Example 1

[0047] like Figure 1 As shown, this embodiment provides a molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving, including: boiler 1, steam turbine generator set 2, boiler feedwater system, molten salt thermal storage unit and molten salt heat release unit;

[0048] The main steam outlet and reheat steam outlet of boiler 1 are connected to the corresponding steam inlets of turbine generator set 2, respectively. The exhaust steam outlet of turbine generator set 2 is connected to the boiler feedwater system, and the outlet of the boiler feedwater system is connected to the inlet of boiler 1. The high-temperature and high-pressure main steam generated by boiler 1 enters turbine generator set 2 to perform power generation. The exhaust steam (i.e., low-pressure exhaust steam) after performing power generation enters the boiler feedwater system, and after condensation and heating, it returns to boiler 1 to form a complete cycle.

[0049] This embodiment achieves both heat storage peak shaving mode and heat release peak mode by setting up molten salt heat storage unit and molten salt heat release unit.

[0050] like Figure 2 As shown, when the power grid requires generator sets to reduce load for deep peak shaving, the system enters the thermal storage working mode.

[0051] The molten salt thermal storage unit is connected to the steam turbine generator set 2 and the boiler 1 through the first and second extraction steam pipelines. It extracts steam from the corresponding parts to heat the molten salt for thermal storage, thereby improving the deep peak-shaving capacity of the coal-fired power unit.

[0052] The molten salt thermal storage unit extracts a portion of high-temperature steam from key components of the turbine generator set 2 and boiler 1 via the first and second extraction steam pipelines, respectively. This extracted steam is no longer used for power generation or conventional heating; instead, it is guided to the molten salt thermal storage unit, where its thermal energy is transferred to the low-temperature molten salt, thereby heating the salt to a high temperature and storing it. By actively extracting and transferring the energy of this steam, the amount of steam required to drive the turbine is directly reduced. This lowers the power output of the generator 204 while maintaining the boiler 1's combustion conditions essentially unchanged, achieving deep peak shaving.

[0053] like Figure 3 As shown, when the power grid needs generator sets to quickly increase the load to cope with peak electricity demand, the system enters the heat dissipation mode.

[0054] The molten salt exothermic unit heats the boiler feedwater by releasing the stored heat of high-temperature molten salt to achieve rapid peak power generation for coal-fired power units.

[0055] The molten salt used is ternary molten salt or other molten salts. The molten salt has a lower melting point, allowing for lower controllable operating temperatures, while the maximum permissible operating temperature is no more than 450℃. The molten salt's heat storage and release units are better suited to the steam-water system of coal-fired power units. The molten salt's operating temperature range is 160~450℃.

[0056] Example 2

[0057] This embodiment describes the steam turbine generator set 2 and the boiler feedwater system based on the overall architecture of Embodiment 1.

[0058] The steam turbine generator set 2 includes a steam turbine and a generator 204. The steam turbine includes a high-pressure cylinder 201, an intermediate-pressure cylinder 202, and a low-pressure cylinder 203.

[0059] The main steam and hot reheat steam generated by boiler 1 are respectively delivered to the steam inlets of high-pressure cylinder 201 and intermediate-pressure cylinder 202;

[0060] The first extraction steam pipeline extracts a portion of the hot reheat steam from the hot reheat steam header between the outlet of boiler 1 and the steam inlet of intermediate pressure cylinder 202.

[0061] The second extraction pipeline extracts a portion of steam from the intermediate stage of the high-pressure cylinder 201.

[0062] This embodiment clarifies the steam source used for heating molten salt in the thermal storage and peak-shaving mode. The system is equipped with two steam extraction pipelines, which extract steam from two different locations:

[0063] First extraction steam pipeline: This pipeline is connected to the hot reheat steam header. The steam extracted from here is the hot reheat steam that has just been heated from the reheat section of boiler 1 and is ready to enter the intermediate pressure cylinder 202.

[0064] Second extraction steam line: This line is connected to the intermediate stage of high-pressure cylinder 201. The steam extracted from here is a portion of the steam in high-pressure cylinder 201 that has not yet fully expanded and done work.

[0065] The boiler feedwater system includes a condenser 3, a condensate pump 4, a low-pressure heater group 5, a deaerator 6, a boiler feedwater pump 7, and a high-pressure heater group 8 connected in series via pipelines.

[0066] Condenser 3 condenses the exhaust steam from low-pressure cylinder 203 into water;

[0067] The low-pressure heater group 5 consists of multiple heaters connected in series. Steam is drawn from different parts of the low-pressure cylinder 203 as heating steam to heat the condensate in stages.

[0068] Deaerator 6 draws steam from intermediate pressure cylinder 202 as its heating steam to remove dissolved oxygen and other non-condensable gases from the feedwater of boiler 1.

[0069] Boiler feed pump 7 draws water from deaerator 6, which is then pressurized, heated by high-pressure heater group 8, and then sent to boiler 1.

[0070] The high-pressure heater group 8 consists of multiple heaters connected in series, which draw steam from the intermediate-pressure cylinder 202 and the high-pressure cylinder 201 respectively to heat the boiler feedwater in stages.

[0071] Example 3

[0072] This embodiment describes the internal structure of the molten salt thermal storage unit.

[0073] The molten salt thermal storage unit includes a low-temperature molten salt tank 9, a high-temperature molten salt tank 14, a molten salt heater, and a low-temperature molten salt pump 10;

[0074] The outlet of the cryogenic molten salt tank 9 is connected to the molten salt inlet of the molten salt heater via the cryogenic molten salt pump 10; the molten salt outlet of the molten salt heater is connected to the inlet of the high-temperature molten salt tank 14.

[0075] The hot reheat steam extracted from the first extraction steam pipeline and the steam extracted from the intermediate stage of the high-pressure cylinder 201 from the second extraction steam pipeline are respectively delivered to the molten salt heater to heat the molten salt flowing out of the low-temperature molten salt tank 9 in stages.

[0076] When the thermal storage mode is activated, the cryogenic molten salt pump 10 draws cryogenic molten salt from the cryogenic molten salt tank 9 and pumps it into the molten salt heater. Inside the molten salt heater, the molten salt flows through heat exchange equipment, fully exchanging heat with the high-temperature steam, thus raising its own temperature. Finally, the heated high-temperature molten salt is transported to the high-temperature molten salt tank 14 for storage.

[0077] The molten salt heater includes a first heat exchanger 11, a second heat exchanger 12, and a third heat exchanger 13; the heat source for the molten salt heater comes from the two extraction steam lines defined in Embodiment 2.

[0078] The steam inlet of the third heat exchanger 13 is connected to the first extraction steam pipeline, the steam outlet of the third heat exchanger 13 is connected to the steam inlet of the first heat exchanger 11, and the steam condensate outlet of the first heat exchanger 11 is connected to the deaerator 6 of the boiler feedwater system.

[0079] The steam inlet of the second heat exchanger 12 is connected to the second extraction steam pipeline, and the slightly superheated steam from the steam outlet of the second heat exchanger 12 flows into the cold reheat steam header and is connected to the boiler 1.

[0080] Among them, the third heat exchanger 13 and the second heat exchanger 12 use only the sensible heat of steam to heat the molten salt, while the first heat exchanger 11 uses the remaining sensible heat and latent heat after steam heat exchange to heat the molten salt.

[0081] Steam from the first extraction pipeline first enters the third heat exchanger 13, releasing some heat energy, and then enters the first heat exchanger 11 to continue releasing heat energy. Sensible heat is used for heat exchange in the third heat exchanger 13. The remaining sensible heat and all latent heat continue to be released in the first heat exchanger 11, condensing into liquid water, which is then transported to the deaerator 6 in the boiler feedwater system for recovery.

[0082] Steam from the second extraction pipeline is introduced into the second heat exchanger 12, where its sensible heat is used to heat the molten salt. The resulting slightly superheated steam is guided and fed into the power plant's cold reheat steam header, and finally returned to boiler 1 for reheating.

[0083] Example 4

[0084] This embodiment describes the internal structure of the molten salt exothermic unit.

[0085] The molten salt heat release unit includes a high-temperature molten salt pump 15 and a feedwater heater 16. The inlet of the high-temperature molten salt pump 15 is connected to the outlet of the high-temperature molten salt tank 14, and the outlet of the feedwater heater 16 is connected to the inlet of the low-temperature molten salt tank 9. The high-temperature molten salt pump 15 transports high-temperature molten salt to the feedwater heater 16, where the heat released by the high-temperature molten salt heat release is used to heat part of the boiler feedwater.

[0086] The feedwater heater 16 is connected to the bypass of the high-pressure heater group 8. When the coal-fired power unit needs peak power, the feedwater heater 16 is put into operation. The boiler feedwater from the boiler feedwater pump 7 flows through the high-pressure heater group (8) and the feedwater heater (16) respectively for heating before converging into the boiler (1). The distribution ratio of the boiler feedwater flow into the feedwater heater (16) can be flexibly adjusted according to the peak power grid requirements.

[0087] Example 5

[0088] This embodiment provides the complete workflow of embodiments one through four.

[0089] I. Thermal storage and peak shaving operation mode.

[0090] When a coal-fired power unit receives a peak-shaving command from the power grid, boiler 1 can maintain the existing load or gradually reduce the load. When entering deep peak-shaving, boiler 1 can maintain the minimum stable combustion load. At this time, the molten salt thermal storage unit is started, and steam is extracted for molten salt thermal storage to reduce the work done by the steam turbine, thereby quickly reducing the electricity generated by the coal-fired power unit. This helps to improve the deep peak-shaving and frequency regulation capabilities of the coal-fired power unit and to a certain extent realizes the decoupling of the boiler and turbine.

[0091] The specific working process of the molten salt thermal storage unit is as follows: The low-temperature molten salt pump 10 is started to draw low-temperature molten salt from the low-temperature molten salt tank 9 and flows through the first heat exchanger 11, the second heat exchanger 12 and the third heat exchanger 13 in sequence. After the low-temperature molten salt is heated step by step through the three sets of heat exchangers, it becomes high-temperature molten salt and enters the high-temperature molten salt tank 14 for storage.

[0092] A portion of the hot reheat steam is extracted as the heating source for the third heat exchanger 13. In the third heat exchanger 13, the sensible heat of the hot reheat steam is used to heat the molten salt for the third time. After heat exchange in the third heat exchanger 13, the steam enters the first heat exchanger 11. In the first heat exchanger 11, the remaining sensible heat and all latent heat of the steam are used to heat the molten salt for the first time. After heat exchange, the steam becomes liquid water, which flows into the deaerator 6 for reuse.

[0093] The intermediate stage steam extracted from the high-pressure cylinder 201 is used as the heating source for the second heat exchanger 12. In the second heat exchanger 12, the sensible heat of the intermediate stage steam extracted from the high-pressure cylinder 201 is used to continue to heat the molten salt for the second time. The steam after heat exchange is still slightly superheated steam. This steam is then merged into the cold reheat steam header and enters the reheat section of boiler 1 together with the cold reheat steam for heating and temperature rise, generating hot reheat steam.

[0094] II. Exothermic Peak Operating Mode

[0095] When a coal-fired power unit receives a power grid instruction to rapidly increase power generation, boiler 1 can maintain the existing load or gradually increase the load. At this time, the molten salt heat release unit is started to increase the amount of steam for the turbine to do work as soon as possible, so as to quickly increase the turbine's power output, thereby improving the coal-fired power unit's peak capacity and load ramp-up rate, and better meeting the power grid's demand for rapid peak generation.

[0096] The specific working process of molten salt exothermic reaction is as follows: the high-temperature molten salt pump 15 is started to draw high-temperature molten salt from the high-temperature molten salt tank 14, which flows through the feed water heater 16 and then enters the low-temperature molten salt tank 9.

[0097] Boiler feedwater pump 7 draws deoxygenated water from deaerator 6 and sends it to the cold end inlet of feedwater heater 16. The heat released by the high-temperature molten salt heats the feedwater entering feedwater heater 16, thereby increasing the feedwater temperature entering boiler 1. The feedwater temperature of deaerator 6 must be strictly controlled at more than 20°C higher than the melting point of molten salt to ensure that the molten salt does not condense during transportation.

[0098] The feedwater heater 16 is connected to the bypass of the high-pressure heater group 8. When the coal-fired power unit needs peak power, the feedwater heater 16 is put into operation. The boiler feedwater from the boiler feedwater pump 7 flows through the high-pressure heater group 8 and the feedwater heater 16 respectively for heating before converging into the boiler 1. The distribution ratio of the boiler feedwater flow into the feedwater heater 16 can be flexibly adjusted according to the peak power grid requirements.

[0099] Using the heat released by the high-temperature molten salt to heat the boiler feedwater can directly reduce the heating output of the high-pressure heater group 8, thereby significantly reducing the heating steam consumption required by the high-pressure heater group 8. This reduces the amount of steam drawn from the high-pressure cylinder 201 and the intermediate-pressure cylinder 202 by the high-pressure heater group 8 as heating steam, thereby rapidly increasing the power output of the high-pressure cylinder 201 and the intermediate-pressure cylinder 202 so that more electricity can be generated to meet the peak demand of the power grid.

[0100] Those skilled in the art should understand that the above embodiments are merely for clearly illustrating the present invention and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications can be made based on the above-described invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving capabilities, characterized in that, include: Boiler (1), steam turbine generator set (2), boiler feedwater system, molten salt thermal storage unit and molten salt heat release unit; The main steam outlet and hot reheat steam outlet of the boiler (1) are respectively connected to the steam inlet of the turbine generator set (2); the exhaust steam outlet of the turbine generator set (2) is connected to the boiler feedwater system, and the outlet of the boiler feedwater system is connected to the inlet of the boiler (1); The molten salt thermal storage unit is connected to the steam turbine generator set (2) and the boiler (1) through the first extraction steam pipeline and the second extraction steam pipeline. It extracts steam from the corresponding part to heat the molten salt for thermal storage, which is used to improve the deep peak shaving capacity of the coal-fired power unit. The molten salt exothermic unit heats the boiler feedwater by releasing the stored heat of high-temperature molten salt to achieve rapid peak power generation for coal-fired power units.

2. The molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving as described in claim 1, characterized in that, The steam turbine generator set (2) includes a steam turbine and a generator (204), and the steam turbine includes a high-pressure cylinder (201), an intermediate-pressure cylinder (202), and a low-pressure cylinder (203). The main steam and hot reheat steam generated by the boiler (1) are respectively delivered to the steam inlets of the high-pressure cylinder (201) and the intermediate-pressure cylinder (202); The first extraction steam pipeline extracts a portion of the hot reheat steam from the hot reheat steam header between the outlet of the boiler (1) and the steam inlet of the intermediate pressure cylinder (202); The second extraction pipeline extracts a portion of the steam from the intermediate stage of the high-pressure cylinder (201).

3. The molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving as described in claim 2, characterized in that, The boiler feedwater system includes a condenser (3), a condensate pump (4), a low-pressure heater group (5), a deaerator (6), a boiler feedwater pump (7), and a high-pressure heater group (8) connected in series by pipelines. The condenser (3) condenses the exhaust steam from the low-pressure cylinder (203) into water; The low-pressure heater group (5) consists of multiple heaters connected in series. Steam is drawn from different parts of the low-pressure cylinder (203) as heating steam to heat the condensate step by step. The deaerator (6) draws steam from the intermediate pressure cylinder (202) as its heating steam to remove dissolved oxygen and other non-condensable gases from the boiler feedwater. The boiler feed pump (7) draws water from the deaerator (6), pressurizes it, heats it through the high-pressure heater group (8), and then sends it into the boiler (1). The high-pressure heater group (8) consists of multiple heaters connected in series, which draw steam from the intermediate-pressure cylinder (202) and the high-pressure cylinder (201) respectively to heat the boiler feedwater step by step.

4. The molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving as described in claim 1, characterized in that, The molten salt thermal storage unit includes a low-temperature molten salt tank (9), a high-temperature molten salt tank (14), a molten salt heater, and a low-temperature molten salt pump (10). The outlet of the cryogenic molten salt tank (9) is connected to the molten salt inlet of the molten salt heater via the cryogenic molten salt pump (10); the molten salt outlet of the molten salt heater is connected to the inlet of the high-temperature molten salt tank (14); The hot reheat steam extracted by the first extraction steam pipeline and part of the steam extracted from the intermediate stage of the high-pressure cylinder (201) by the second extraction steam pipeline are respectively delivered to the molten salt heater to heat the molten salt flowing out of the low-temperature molten salt tank (9) step by step.

5. The molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving as described in claim 4, characterized in that, The molten salt heater includes a first heat exchanger (11), a second heat exchanger (12) and a third heat exchanger (13). The steam inlet of the third heat exchanger (13) is connected to the first extraction steam pipeline, the steam outlet of the third heat exchanger (13) is connected to the steam inlet of the first heat exchanger (11), and the steam condensate outlet of the first heat exchanger (11) is connected to the deaerator (6) of the boiler feedwater system. The steam inlet of the second heat exchanger (12) is connected to the second extraction steam pipeline, and the slightly superheated steam from the steam outlet of the second heat exchanger (12) flows into the cold reheat steam header and is connected to the boiler (1).

6. The molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving as described in claim 5, characterized in that, The third heat exchanger (13) and the second heat exchanger (12) both use only the sensible heat of steam to heat the molten salt, while the first heat exchanger (11) uses the remaining sensible heat and latent heat after steam heat exchange to heat the molten salt.

7. The molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving as described in claim 1, characterized in that, The molten salt heat release unit includes a high-temperature molten salt pump (15) and a feedwater heater (16). The inlet of the high-temperature molten salt pump (15) is connected to the outlet of the high-temperature molten salt tank (14), and the outlet of the feedwater heater (16) is connected to the inlet of the low-temperature molten salt tank (9). The high-temperature molten salt pump (15) transports high-temperature molten salt to the feedwater heater (16), and the heat released by the high-temperature molten salt heat release is used in the feedwater heater (16) to heat part of the boiler feedwater.

8. The molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving as described in claim 7, characterized in that, The feedwater heater (16) is connected to the bypass of the high-pressure heater group (8). When the coal-fired power unit needs peak power, the feedwater heater (16) is put into operation. The boiler feedwater from the boiler feedwater pump (7) flows through the high-pressure heater group (8) and the feedwater heater (16) respectively for heating before converging into the boiler (1). The distribution ratio of the boiler feedwater flow into the feedwater heater (16) can be flexibly adjusted according to the peak power grid requirements.

9. The molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving as described in claim 1, characterized in that, The working temperature range of molten salt is 160~450℃.

10. The molten salt energy storage coupled with coal-fired power generation system with deep peak shaving and rapid peak shaving as described in claim 9, characterized in that, The molten salt used is a ternary molten salt or another molten salt.

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