Coupling double-tank indirect solar photo-thermal boiler complementary steam supply system and method

Abstract

The invention provides a coupled double-tank indirect solar photo-thermal boiler complementary steam supply system and method. The coupled double-tank indirect solar photo-thermal boiler complementary steam supply system comprises a solar tower, a main heat exchanger, a high-temperature fused salt storage tank, a low-temperature fused salt storage tank, a fused salt storage heat exchanger, a first heat exchanger and a coal-fired unit. A hot end inlet and a cold end outlet of the fused salt storage heat exchanger are respectively connected with a high-temperature fused salt outlet and a low-temperature fused salt inlet of the solar tower; a hot end inlet and a cold end outlet of the main heat exchanger are respectively connected with a high-temperature fused salt outlet and a low-temperature fused salt inlet of the solar tower; the fused salt storage heat exchanger is respectively connected with the high-temperature fused salt storage tank and the low-temperature fused salt storage tank; the main heat exchanger is connected with the fused salt storage heat exchanger and the first heat exchanger. A cold end inlet of the first heat exchanger is connected with a water supply pipeline at a first inlet of a boiler of the coal-fired unit, and a hot end outlet of the first heat exchanger is connected with a main steam pipeline at a first outlet of the boiler. The system can guarantee the industrial steam supply demand under the deep peak regulation state of the unit, and can also reduce the power generation coal consumption of the unit.

Description

Technical Field

[0001] This invention belongs to the field of energy utilization technology, specifically relating to a boiler complementary steam supply system and method with coupled dual-tank indirect solar thermal power. Background Technology

[0002] Under the current dual-carbon requirements of achieving carbon peaking and carbon neutrality, the proportion of renewable energy sources such as wind and solar power is becoming increasingly significant. However, the intermittent and fluctuating nature of these renewable energy sources presents new challenges to the power grid. Against this backdrop, combined heat and power (CHP) units, while providing industrial steam, also frequently participate in peak shaving. This forces existing thermal power units to meet the parameter requirements of dual-stage industrial steam supply by employing main steam desuperheating and pressure reduction methods under low-load conditions, resulting in poor thermal economy and increased coal consumption.

[0003] There are four commonly used high-pressure industrial steam supply technologies for existing cogeneration units: cold resteam extraction heating, hot resteam extraction heating, main steam desuperheating and pressure reduction heating, and main steam back-pressure turbine heating. For the most commonly used 300MW-class thermal power units in China, cold resteam extraction heating and hot resteam extraction heating are difficult to provide the required steam pressure of 3MPa and a steam supply of 100t / h under 50% THA conditions. Main steam desuperheating and pressure reduction heating can meet the high-pressure steam supply requirements under low-load conditions, but its economic efficiency is poor. Heating via main steam back-pressure turbine requires the construction of a new back-pressure turbine plant, the purchase of the back-pressure turbine and related valves, resulting in high initial investment costs, especially when steam demand fluctuates, leading to unstable economic returns.

[0004] To address the aforementioned issues, it is necessary to propose a reasonably designed and effective solution to the problems of a coupled dual-tank indirect solar thermal boiler complementary steam supply system and method. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a boiler complementary steam supply system and method with coupled dual-tank indirect solar thermal power.

[0006] One aspect of the present invention provides a boiler complementary steam supply system with coupled dual-tank indirect solar thermal power, including a solar tower, a main heat exchanger, a high-temperature molten salt storage tank, a low-temperature molten salt storage tank, a molten salt storage and discharge heat exchanger, a first heat exchanger, and a coal-fired unit. The hot end inlet and cold end outlet of the molten salt storage heat exchanger are respectively connected to the high-temperature molten salt outlet and low-temperature molten salt inlet of the solar tower. The hot end inlet and cold end outlet of the main heat exchanger are respectively connected to the high-temperature molten salt outlet and low-temperature molten salt inlet of the solar tower. The molten salt storage heat exchanger is connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank respectively, and is used to exchange heat between the high-temperature molten salt in the high-temperature molten salt storage tank and the low-temperature molten salt in the low-temperature molten salt storage tank. The main heat exchanger is connected to the molten salt storage heat exchanger and the first heat exchanger, respectively. The cold end inlet of the first heat exchanger is connected to the feedwater pipe at the first inlet of the boiler of the coal-fired unit, and the hot end outlet of the first heat exchanger is connected to the main steam pipe at the first outlet of the boiler.

[0007] Optionally, the system further includes a second heat exchanger; The cold end inlet of the second heat exchanger is connected to the condensate pipe at the deaerator outlet of the coal-fired unit, and the hot end outlet of the second heat exchanger is connected to the reheat steam pipe at the second outlet of the boiler; wherein, the condensate pipe is equipped with a water pump for pressurizing the condensate.

[0008] Optionally, the outlet of the main heat exchanger is connected to the inlet of the first heat exchanger and the inlet of the second heat exchanger, respectively; The inlet of the main heat exchanger is connected to the outlet of the first heat exchanger and the outlet of the second heat exchanger, respectively.

[0009] Optionally, the system may also include a third heat exchanger; The inlet of the third heat exchanger is connected to the outlet of the first heat exchanger and the outlet of the second heat exchanger, respectively, and the outlet of the third heat exchanger is connected to the inlet of the main heat exchanger.

[0010] Optionally, the cold end inlet of the third heat exchanger is connected to the condensate pipe at the outlet of the deaerator; wherein, After the condensate is pressurized, it absorbs heat in the third heat exchanger to form industrial steam, which is then used for external heating.

[0011] Optionally, a cold resteam header is provided at the second inlet of the boiler; wherein, Steam is extracted from the cold resteam header and then directly supplied to the industry.

[0012] Another aspect of the present invention provides a boiler complementary steam supply method for coupled dual-tank indirect solar thermal power, employing the boiler complementary steam supply system for coupled dual-tank indirect solar thermal power described above, the method comprising: Under sufficient sunlight, a portion of the high-temperature molten salt in the solar tower enters the molten salt storage heat exchanger to release heat and heat the low-temperature molten salt in the low-temperature molten salt storage tank; a portion of the high-temperature molten salt in the solar tower enters the main heat exchanger to release heat and supply heat to the first heat exchanger; the low-temperature molten salt in the low-temperature molten salt storage tank enters the molten salt storage heat exchanger to absorb heat and becomes high-temperature molten salt, and then returns to the high-temperature molten salt storage tank for heat storage; In the absence of sufficient sunlight, the high-temperature molten salt in the high-temperature molten salt storage tank enters the molten salt storage and release heat exchanger to release heat and become low-temperature molten salt before returning to the low-temperature molten salt storage tank; the molten salt medium in the main heat exchanger absorbs heat in the molten salt storage and release heat exchanger, and then returns to the main heat exchanger to release heat to supply heat to the first heat exchanger. During the operation of the coal-fired unit, the feedwater at the first inlet of the boiler is delivered to the first heat exchanger to absorb heat and form high-temperature and high-pressure steam, which is then delivered to the main steam pipeline at the first outlet of the boiler through the first outlet of the first heat exchanger.

[0013] Optionally, the method further includes: The condensate at the outlet of the deaerator is pressurized and then sent to the second heat exchanger. After absorbing heat in the second heat exchanger, it forms high-temperature steam, which is then sent to the reheat steam pipeline at the second outlet of the boiler.

[0014] Optionally, the method further includes: The condensate at the outlet of the deaerator is pressurized and transported to the third heat exchanger, where it absorbs heat to form 3MPa-level industrial steam for external heating.

[0015] Optionally, the method further includes: Steam is extracted directly from the cold resteam header to provide industrial steam at a pressure of 1.5 MPa.

[0016] The present invention relates to a coupled dual-tank indirect solar thermal boiler complementary steam supply system and method. This system forms a steam production system that complements solar thermal and coal-fired boilers. It creatively combines a solar thermal energy storage system with a traditional coal-fired unit, realizing the combination of clean and low-carbon new energy sources and continuous and reliable coal power. It achieves multi-level utilization of solar energy, which can not only ensure the industrial steam supply demand under deep peak shaving conditions of the unit, but also reduce the coal consumption of the unit for power generation, thus contributing to energy conservation and emission reduction and achieving dual carbon goals. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a boiler complementary steam supply system with coupled dual tanks and indirect solar thermal power, according to an embodiment of the present invention. Figure 2This is a schematic flowchart of a boiler complementary steam supply method for coupled dual-tank indirect solar thermal power, according to another embodiment of the present invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1 As shown, one aspect of the present invention provides a boiler complementary steam supply system with coupled dual-tank indirect solar thermal power, including a solar tower 1, a main heat exchanger 2, a high-temperature molten salt storage tank 3, a low-temperature molten salt storage tank 4, a molten salt storage and release heat exchanger 5, a first heat exchanger 6, and a coal-fired unit.

[0020] The coal-fired power unit includes a boiler 7, a high-pressure cylinder 8, an intermediate-pressure cylinder 9, and a low-pressure cylinder 10 connected in sequence, a generator G connected to the low-pressure cylinder 10, a deaerator 11 connected to the intermediate-pressure cylinder 9, three high-pressure heaters 12 sequentially installed in the feedwater pipeline between the outlet of the deaerator 11 and the first inlet of the boiler 7, and a condenser 13 connected to the low-pressure cylinder 10 and the deaerator 11 respectively. In other words, the coal-fired power unit is a conventional coal-fired power unit, and its composition can be referenced from the composition of existing coal-fired power units in the prior art, which will not be elaborated further here.

[0021] The hot end inlet and cold end outlet of the molten salt storage heat exchanger 5 are respectively connected to the high-temperature molten salt outlet and low-temperature molten salt inlet of the solar tower 1.

[0022] Specifically, under sufficient sunlight, a portion of the high-temperature molten salt absorbed by the solar energy in the solar tower 1 is transported from the high-temperature molten salt outlet of the solar tower 1 to the hot end inlet of the molten salt storage heat exchanger 5. After releasing heat in the molten salt storage heat exchanger 5, the high-temperature molten salt becomes low-temperature molten salt, which is then transported from the cold end outlet of the molten salt storage heat exchanger 5 to the low-temperature molten salt inlet of the solar tower 1. The high-temperature molten salt releases heat in the molten salt storage heat exchanger 5 to heat the molten salt in the low-temperature molten salt storage tank 4.

[0023] The hot end inlet and cold end outlet of the main heat exchanger 2 are respectively connected to the high-temperature molten salt outlet and low-temperature molten salt inlet of the solar tower 1.

[0024] Specifically, under sufficient sunlight, a portion of the high-temperature molten salt absorbed by the solar energy in the solar tower 1 is transported from the high-temperature molten salt outlet of the solar tower 1 to the hot end inlet of the main heat exchanger 2 to release heat and transform into low-temperature molten salt. The low-temperature molten salt is then transported from the cold end outlet of the main heat exchanger 2 to the low-temperature molten salt inlet of the solar tower 1. The high-temperature molten salt, after entering the main heat exchanger 2, is used to supply the heat required by the first heat exchanger 6, thereby replacing the boiler 7 of the coal-fired unit in providing a portion of the main steam.

[0025] The molten salt storage heat exchanger 5 is connected to the high-temperature molten salt storage tank 3 and the low-temperature molten salt storage tank 4 respectively, and is used to exchange heat between the high-temperature molten salt in the high-temperature molten salt storage tank 3 and the low-temperature molten salt in the low-temperature molten salt storage tank 4.

[0026] Specifically, under conditions of sufficient sunlight, solar heat is stored in a high-temperature molten salt storage tank 3 via a molten salt storage heat exchanger 5. During the heat storage process, low-temperature molten salt flows out of the low-temperature molten salt storage tank 4, absorbs heat through the molten salt storage heat exchanger 5, and becomes high-temperature molten salt, which then enters the high-temperature molten salt storage tank 3 for storage. Under conditions of insufficient sunlight, the high-temperature molten salt in the high-temperature molten salt storage tank 3 releases heat through the molten salt storage heat exchanger 5 and becomes low-temperature molten salt, which then enters the low-temperature molten salt storage tank 4 for storage.

[0027] The main heat exchanger 2 is connected to the molten salt storage heat exchanger 5 and the first heat exchanger 6, respectively.

[0028] Specifically, when there is insufficient sunlight, the molten salt medium in the main heat exchanger 2 absorbs heat in the molten salt storage heat exchanger 5, and then returns to the main heat exchanger 2 to release heat to supply heat to the first heat exchanger 6, thereby replacing the boiler 7 of the coal-fired unit to provide part of the main steam.

[0029] The cold end inlet of the first heat exchanger 6 is connected to the water supply pipe 14 at the first inlet of the boiler 7 of the coal-fired unit, and the hot end outlet of the first heat exchanger 6 is connected to the main steam pipe 15 at the first outlet of the boiler 7.

[0030] Specifically, the feedwater at the first inlet of the boiler 7 is transported to the first heat exchanger 6 through the cold end inlet to absorb heat and form high-temperature, high-pressure steam. Then, it is transported through the hot end outlet of the first heat exchanger 6 to the main steam pipeline 15 at the first outlet of the boiler 7, and merges into the main steam cycle of the coal-fired unit. In other words, the first heat exchanger 6 provides part of the main steam instead of the boiler 7, and this steam production process forms a complementary steam system of solar thermal energy and coal-fired boiler.

[0031] The present invention relates to a coupled dual-tank indirect solar thermal boiler complementary steam supply system. This system forms a complementary steam production system of solar thermal and coal-fired boilers. It creatively combines a solar thermal energy storage system with a traditional coal-fired unit, realizing the combination of clean and low-carbon new energy and continuous and reliable coal power. It achieves multi-level utilization of solar energy, which can not only ensure the industrial steam supply demand under deep peak shaving conditions of the unit, but also reduce the coal consumption of the unit for power generation, thus contributing to energy conservation and emission reduction and achieving dual carbon goals.

[0032] Optional, such as Figure 1As shown, the system also includes a second heat exchanger 16; the cold end inlet of the second heat exchanger 16 is connected to the condensate pipe 17 at the outlet of the deaerator 11 of the coal-fired unit, and the hot end outlet of the second heat exchanger 16 is connected to the reheat steam pipe 18 at the second outlet of the boiler 7; wherein, the condensate pipe 17 is equipped with a water pump 19 for pressurizing the condensate.

[0033] Specifically, the condensate at the outlet of deaerator 11 is pressurized by water pump 19 to the pressure required for industrial steam supply and then transported to the second heat exchanger 16. In the second heat exchanger 16, it absorbs heat to form high-temperature steam, which is then transported to the reheat steam pipeline 18 at the second outlet of the boiler 7. This steam production process forms a complementary steam system of solar thermal and coal-fired boiler.

[0034] For example, such as Figure 1 As shown, the outlet of the main heat exchanger 2 is connected to the inlet of the first heat exchanger 6 and the inlet of the second heat exchanger 16, respectively; the inlet of the main heat exchanger 2 is connected to the outlet of the first heat exchanger 6 and the outlet of the second heat exchanger 16, respectively.

[0035] Specifically, the molten salt medium in the main heat exchanger 2 absorbs heat and then releases heat in the first heat exchanger 6 and the second heat exchanger 16, respectively, to provide the required heat for the first heat exchanger 6 and the second heat exchanger 16.

[0036] For example, such as Figure 1 As shown, the system also includes a third heat exchanger 20; the inlet of the third heat exchanger 20 is connected to the outlet of the first heat exchanger 6 and the outlet of the second heat exchanger 16 respectively, and the outlet of the third heat exchanger 20 is connected to the inlet of the main heat exchanger 2.

[0037] Specifically, after absorbing heat, the molten salt medium in the main heat exchanger 2 releases heat in the first heat exchanger 6 and the second heat exchanger 16, providing the required heat to the first heat exchanger 6 and the second heat exchanger 16. The heat is then collected and flows into the third heat exchanger 20 for heat exchange before returning to the main heat exchanger 2. In other words, the molten salt medium in the main heat exchanger 2, after absorbing heat, is used to supply the required heat exchange to the first heat exchanger 6, the second heat exchanger 16, and the third heat exchanger 20.

[0038] For example, such as Figure 1 As shown, the cold end inlet of the third heat exchanger 20 is connected to the condensate pipe 17 at the outlet of the deaerator 11; wherein, after the condensate is pressurized, it absorbs heat in the third heat exchanger 20 to form industrial steam for external heating.

[0039] Specifically, the condensate from the outlet of the deaerator 11 is pressurized by the water pump 19 to the pressure required for industrial steam supply, and then absorbed by the third heat exchanger 20 to form 3MPa-level industrial steam for external heating.

[0040] For example, a cold resteam header 21 is provided at the second inlet of the boiler 7; wherein, steam is extracted from the cold resteam header 21 and then directly supplied to the industrial steam.

[0041] Specifically, a portion of steam is extracted from the unit's cold reheat steam header 21 for 1.5MPa-level industrial steam supply. A portion of the main steam (Q1) is provided by the molten salt energy storage system, and the main steam provided by the boiler is Q2. Considering the boiler reheater overheating limit, the extractable amount of cold reheat steam is Q1 + r × Q2 (where r is the allowable extraction coefficient, typically 5%~8%). Corresponding to conventional cogeneration boiler steam supply, when the main steam provided by the boiler is Q1 + Q2, considering the boiler reheater overheating limit, the extractable amount of cold reheat steam is r × (Q1 + Q2) (where r is the allowable extraction coefficient). In summary, with the same amount of main steam entering the turbine high-pressure cylinder, this invention proposes a system with a larger cold reheat steam extraction capacity, increasing the extraction capacity by (1-r) × Q1.

[0042] like Figure 1 As shown, the system also includes a mirror field 22, which reflects the collected solar radiation energy into the solar tower 1 and converts it into high-temperature thermal energy for storage.

[0043] The boiler complementary steam supply system of the coupled thermotropic layer solar thermal energy storage of the present invention, compared with a conventional 350MW supercritical unit (main steam pressure 24.2MPa, main steam temperature 566℃, reheat steam temperature 566℃, back pressure set at 4.9kPa), when the industrial steam supply parameters are pressure 3MPa, temperature 280℃, steam extraction rate 100t / h, and main steam flow rate set at 1008.51t / h, the coal consumption for power generation of the present invention is only 235.43g / kWh, while the coal consumption for power generation of the conventional cogeneration scheme is only 276.57 g / kWh. The coal consumption for power generation of the present invention is reduced by 41.14 g / kWh, and the coal saving effect is significant.

[0044] For example, such as Figure 2 As shown, another aspect of the present invention provides a boiler complementary steam supply method S100 for coupled dual-tank indirect solar thermal power, employing the boiler complementary steam supply system for coupled dual-tank indirect solar thermal power described above. The specific composition of this boiler complementary steam supply system for coupled dual-tank indirect solar thermal power has been described in detail above and will not be repeated here.

[0045] Specifically, the coupled dual-tank indirect solar thermal boiler complementary steam supply method S100 may include: S110. Under sufficient sunlight, a portion of the high-temperature molten salt in the solar tower enters the molten salt storage heat exchanger to release heat and heat the low-temperature molten salt in the low-temperature molten salt storage tank; a portion of the high-temperature molten salt in the solar tower enters the main heat exchanger to release heat and supply heat to the first heat exchanger; the low-temperature molten salt in the low-temperature molten salt storage tank enters the molten salt storage heat exchanger to absorb heat and becomes high-temperature molten salt, and then returns to the high-temperature molten salt storage tank for heat storage.

[0046] Specifically, under sufficient sunlight, a portion of the high-temperature molten salt absorbed by the solar energy in the solar tower 1 is transported from the high-temperature molten salt outlet of the solar tower 1 to the hot end inlet of the main heat exchanger 2 to release heat and transform into low-temperature molten salt. The low-temperature molten salt is then transported from the cold end outlet of the main heat exchanger 2 to the low-temperature molten salt inlet of the solar tower 1. The high-temperature molten salt, after entering the main heat exchanger 2, is used to supply the heat required by the first heat exchanger 6, thereby replacing the boiler 7 of the coal-fired unit in providing a portion of the main steam.

[0047] Solar heat is stored in a high-temperature molten salt storage tank 3 via a molten salt storage heat exchanger 5. During the heat storage process, low-temperature molten salt flows out of the low-temperature molten salt storage tank 4, absorbs heat through the molten salt storage heat exchanger 5, and becomes high-temperature molten salt, which then enters the high-temperature molten salt storage tank 3 for storage.

[0048] S120. In the absence of sufficient sunlight, the high-temperature molten salt in the high-temperature molten salt storage tank enters the molten salt storage and release heat exchanger to release heat and become low-temperature molten salt before returning to the low-temperature molten salt storage tank; the molten salt medium in the main heat exchanger absorbs heat in the molten salt storage and release heat exchanger, and then returns to the main heat exchanger to release heat to supply heat to the first heat exchanger.

[0049] Specifically, under conditions of insufficient sunlight, the high-temperature molten salt in the high-temperature molten salt storage tank 3 enters the molten salt storage heat exchanger 5 to release heat and becomes low-temperature molten salt, which then enters the low-temperature molten salt storage tank 4 for storage.

[0050] The molten salt medium in the main heat exchanger 2 absorbs heat in the molten salt storage heat exchanger 5, and then returns to the main heat exchanger 2 to release heat to supply heat to the first heat exchanger 6, thereby replacing the boiler 7 of the coal-fired unit to provide part of the main steam.

[0051] S130. During the operation of the coal-fired unit, the feedwater at the first inlet of the boiler is transported to the first heat exchanger to absorb heat and form high-temperature and high-pressure steam, and then transported to the main steam pipeline at the first outlet of the boiler through the first outlet of the first heat exchanger.

[0052] Specifically, during the operation of the coal-fired unit, the feedwater at the first inlet of the boiler 7 is transported to the first heat exchanger 6 through the cold end inlet to absorb heat and form high-temperature, high-pressure steam. This steam is then transported through the hot end outlet of the first heat exchanger 6 to the main steam pipeline 15 at the first outlet of the boiler 7, thus merging into the main steam cycle of the coal-fired unit. In other words, the first heat exchanger 6 provides a portion of the main steam instead of the boiler 7, and this steam production process forms a complementary steam system of solar thermal energy and coal-fired boiler.

[0053] Optionally, the method further includes: The condensate at the outlet of deaerator 11 is pressurized and sent to the second heat exchanger 16, where it absorbs heat to form high-temperature steam, which is then sent to the reheat steam pipeline 18 at the second outlet of boiler 7. This steam production process forms a complementary steam system of solar thermal and coal-fired boiler.

[0054] For example, the method further includes: The condensate at the outlet of the deaerator 11 is pressurized and transported to the third heat exchanger 20. After absorbing heat in the third heat exchanger 20, it forms 3MPa-level industrial steam for external heating.

[0055] For example, the method further includes: Steam is extracted directly from the cold resteam header 21 to provide industrial steam at a pressure of 1.5 MPa.

[0056] The complementary steam supply method for a coupled dual-tank indirect solar thermal boiler of this invention fully utilizes solar heat and combines it with multi-stage heating of condensate into superheated steam for industrial steam supply, achieving multi-stage energy utilization of the thermal system. Furthermore, through the main steam and molten salt system sections of the unit, the cold reheat steam heating flow rate can be significantly increased, reducing heating energy consumption. This invention not only achieves multi-stage utilization of solar energy but also ensures industrial steam supply needs under deep peak-shaving conditions. Implementation of this patented solution can achieve energy conservation and emission reduction, contributing to the achievement of dual-carbon goals.

[0057] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A boiler complementary steam supply system with coupled dual-tank indirect solar thermal power, characterized in that, This includes a solar tower, main heat exchanger, high-temperature molten salt storage tank, low-temperature molten salt storage tank, molten salt storage and discharge heat exchanger, first heat exchanger, and coal-fired unit; The hot end inlet and cold end outlet of the molten salt storage heat exchanger are respectively connected to the high-temperature molten salt outlet and low-temperature molten salt inlet of the solar tower. The hot end inlet and cold end outlet of the main heat exchanger are respectively connected to the high-temperature molten salt outlet and low-temperature molten salt inlet of the solar tower. The molten salt storage heat exchanger is connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank respectively, and is used to exchange heat between the high-temperature molten salt in the high-temperature molten salt storage tank and the low-temperature molten salt in the low-temperature molten salt storage tank. The main heat exchanger is connected to the molten salt storage heat exchanger and the first heat exchanger, respectively. The cold end inlet of the first heat exchanger is connected to the feedwater pipe at the first inlet of the boiler of the coal-fired unit, and the hot end outlet of the first heat exchanger is connected to the main steam pipe at the first outlet of the boiler.

2. The system according to claim 1, characterized in that, The system also includes a second heat exchanger; The cold end inlet of the second heat exchanger is connected to the condensate pipe at the deaerator outlet of the coal-fired unit, and the hot end outlet of the second heat exchanger is connected to the reheat steam pipe at the second outlet of the boiler; wherein, the condensate pipe is equipped with a water pump for pressurizing the condensate.

3. The system according to claim 2, characterized in that, The outlet of the main heat exchanger is connected to the inlet of the first heat exchanger and the inlet of the second heat exchanger, respectively. The inlet of the main heat exchanger is connected to the outlet of the first heat exchanger and the outlet of the second heat exchanger, respectively.

4. The system according to claim 3, characterized in that, The system also includes a third heat exchanger; The inlet of the third heat exchanger is connected to the outlet of the first heat exchanger and the outlet of the second heat exchanger, respectively, and the outlet of the third heat exchanger is connected to the inlet of the main heat exchanger.

5. The system according to claim 4, characterized in that, The cold end inlet of the third heat exchanger is connected to the condensate pipe at the outlet of the deaerator; wherein... After the condensate is pressurized, it absorbs heat in the third heat exchanger to form industrial steam, which is then used for external heating.

6. The system according to claim 1, characterized in that, A cold resteam header is provided at the second inlet of the boiler; wherein... Steam is extracted from the cold resteam header and then directly supplied to the industry.

7. A method for complementary steam supply to a boiler with coupled dual-tank indirect solar thermal power, characterized in that, The method of using the coupled dual-tank indirect solar thermal boiler complementary steam supply system according to any one of claims 1 to 6 includes: Under sufficient sunlight, a portion of the high-temperature molten salt in the solar tower enters the molten salt storage heat exchanger to release heat and heat the low-temperature molten salt in the low-temperature molten salt storage tank; a portion of the high-temperature molten salt in the solar tower enters the main heat exchanger to release heat and supply heat to the first heat exchanger; the low-temperature molten salt in the low-temperature molten salt storage tank enters the molten salt storage heat exchanger to absorb heat and becomes high-temperature molten salt, and then returns to the high-temperature molten salt storage tank for heat storage; In the absence of sufficient sunlight, the high-temperature molten salt in the high-temperature molten salt storage tank enters the molten salt storage and release heat exchanger to release heat and become low-temperature molten salt before returning to the low-temperature molten salt storage tank; the molten salt medium in the main heat exchanger absorbs heat in the molten salt storage and release heat exchanger, and then returns to the main heat exchanger to release heat to supply heat to the first heat exchanger. During the operation of the coal-fired unit, the feedwater at the first inlet of the boiler is delivered to the first heat exchanger to absorb heat and form high-temperature and high-pressure steam, which is then delivered to the main steam pipeline at the first outlet of the boiler through the first outlet of the first heat exchanger.

8. The method according to claim 7, characterized in that, The method further includes: The condensate at the outlet of the deaerator is pressurized and then sent to the second heat exchanger. After absorbing heat in the second heat exchanger, it forms high-temperature steam, which is then sent to the reheat steam pipeline at the second outlet of the boiler.

9. The method according to claim 8, characterized in that, The method further includes: The condensate at the outlet of the deaerator is pressurized and transported to the third heat exchanger, where it absorbs heat to form 3MPa-level industrial steam for external heating.

10. The method according to claim 7, characterized in that, The method further includes: Steam is extracted directly from the cold resteam header to provide industrial steam at a pressure of 1.5 MPa.

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