Coupling double-tank active solar photo-thermal energy storage coal-fired unit two-stage steam supply system

Abstract

The invention provides a coupling double-tank active solar photo-thermal energy storage coal-fired unit two-stage steam supply system which comprises a solar energy storage subsystem, a fused salt heat storage and release subsystem, a first heat exchanger, a second heat exchanger and a coal-fired unit. The fused salt heat storage and release subsystem comprises a low-temperature fused salt tank and a high-temperature fused salt tank which are connected with a low-temperature side inlet and a low-temperature side outlet of the solar energy storage subsystem respectively, and a high-temperature side inlet and a high-temperature side outlet of the first heat exchanger are connected with an outlet of the high-temperature fused salt tank and a high-temperature side inlet of the second heat exchanger respectively; a high-temperature side outlet of the second heat exchanger is connected with an inlet of the low-temperature molten salt tank, the coal-fired unit comprises a boiler and a cylinder block, and a low-temperature side inlet of the second heat exchanger and a steam outlet of the boiler are connected with a steam inlet of the cylinder block. A steam exhaust port of the cylinder group is connected with a steam inlet of the boiler, a low-temperature side inlet of the first heat exchanger and a low-temperature side inlet of the second heat exchanger, and a low-temperature side outlet of the second heat exchanger is used for first industrial steam supply.

Description

Technical Field

[0001] The embodiments of the present invention belong to the field of energy utilization technology, specifically relating to a two-stage steam supply system for coal-fired power units coupled with dual-tank active solar thermal energy storage. Background Technology

[0002] The proportion of renewable energy sources such as wind and solar power is becoming increasingly significant. However, these renewable energy sources are intermittent and volatile, posing new challenges to the power grid. Against this backdrop, combined heat and power (CHP) units, while providing industrial steam, also need to frequently participate in peak shaving. This leads existing thermal power units to meet the parameter requirements of dual-stage industrial steam supply by using main steam desuperheating and pressure reduction 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 supply of 100t / h at an industrial parameter of 3MPa 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 and it is difficult to meet the requirements of the "three-stage" (renovation, upgrading, and transformation) linkage. Heating via main steam back-pressure turbine requires the construction of a new back-pressure turbine plant, the purchase of back-pressure turbines and related valves, resulting in high initial investment costs, especially when steam demand fluctuates, leading to unstable economic returns.

[0004] Therefore, there is an urgent need for a steam supply system that can save energy and reduce emissions. Summary of the Invention

[0005] The embodiments of the present invention aim to at least solve one of the technical problems existing in the prior art, and provide a two-stage steam supply system for coal-fired power units with coupled dual-tank active solar thermal energy storage.

[0006] This invention provides a two-stage steam supply system for coal-fired power units coupled with dual-tank active solar thermal energy storage, comprising: A solar energy storage subsystem, wherein the solar energy storage subsystem is used to absorb solar energy and convert solar energy into thermal energy; A molten salt heat storage and release subsystem includes a high-temperature molten salt tank and a low-temperature molten salt tank. The low-temperature molten salt tank is connected to the low-temperature side inlet of the solar energy storage subsystem, and the high-temperature molten salt tank is connected to the low-temperature side outlet of the solar energy storage subsystem. The first heat exchanger has its high-temperature side inlet connected to the outlet of the high-temperature molten salt tank. The second heat exchanger has its high-temperature side inlet connected to the high-temperature side outlet of the first heat exchanger, and its high-temperature side outlet connected to the inlet of the low-temperature molten salt tank. A coal-fired power unit, comprising a boiler and a cylinder assembly, wherein the steam outlet of the boiler is connected to the steam inlet of the cylinder assembly, the steam outlet of the cylinder assembly is connected to the steam inlet of the boiler, the steam outlet of the cylinder assembly is connected to the low-temperature side inlet of a first heat exchanger, the low-temperature side outlet of the first heat exchanger is connected to the steam inlet of the cylinder assembly, and the steam outlet of the cylinder assembly is connected to the low-temperature side inlet of a second heat exchanger, the low-temperature side outlet of the second heat exchanger being used for first industrial steam supply.

[0007] In some embodiments of the present invention, the pressure of the steam output from the low-temperature side outlet of the second heat exchanger is 3 MPa.

[0008] In some embodiments of the present invention, the temperature of the steam output from the low-temperature side outlet of the second heat exchanger is 300°C.

[0009] In some embodiments of the present invention, the cylinder group includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder connected coaxially in sequence. The exhaust ports of the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder are respectively connected to the low-temperature side inlet of the first heat exchanger, and the low-temperature side outlet of the first heat exchanger is connected to the inlet of the high-pressure cylinder.

[0010] In some embodiments of the present invention, the coal-fired unit further includes a deaerator, wherein the exhaust port of the high-pressure cylinder, the exhaust port of the intermediate-pressure cylinder and the exhaust port of the low-pressure cylinder are respectively connected to the deaerator, and the deaerator is connected to the low-temperature side inlet of the first heat exchanger.

[0011] In some embodiments of the present invention, the deaerator is connected to the low-temperature side inlet of the second heat exchanger.

[0012] In some embodiments of the present invention, the deaerator is connected to the steam inlet of the boiler.

[0013] In some embodiments of the present invention, the exhaust port of the high-pressure cylinder includes a high-temperature exhaust port and a low-temperature exhaust port. The high-temperature exhaust port and the low-temperature exhaust port are respectively connected to the deaerator. The high-temperature exhaust port is connected to the reheat steam inlet of the boiler. The reheat steam outlet of the boiler is connected to the steam inlet of the intermediate-pressure cylinder. The high-temperature exhaust port is used for second industrial steam supply.

[0014] In some embodiments of the present invention, the pressure of the industrial steam output from the high-temperature exhaust port is different from the pressure of the industrial steam output from the low-temperature side outlet of the second heat exchanger.

[0015] In some embodiments of the present invention, the pressure of the industrial steam output from the high-temperature exhaust port is 1.5 MPa.

[0016] This invention relates to a coupled dual-tank active solar thermal energy storage system for a coal-fired power unit, which couples a solar energy storage subsystem with the coal-fired power unit via a molten salt heat storage and release subsystem and two heat exchangers. The energy stored in the solar energy storage subsystem is stored as thermal energy in a high-temperature molten salt tank. The high-temperature salt in the molten salt tank sequentially flows through a first heat exchanger and a second heat exchanger, releasing heat. A portion of the low-temperature steam discharged from the cylinder assembly of the coal-fired power unit enters the first heat exchanger to absorb the heat released by the high-temperature salt, generating high-temperature steam for use by the cylinder assembly. A portion of the low-temperature steam enters the second heat exchanger to absorb the heat released by the high-temperature salt a second time, raising its temperature for use as the first industrial steam supply. By utilizing the energy of the solar energy storage subsystem to heat the low-temperature steam, while meeting the grid's deep peak-shaving requirements, this system can both guarantee industrial steam supply and reduce the boiler steam output of the coal-fired power unit, thereby reducing the coal consumption for power generation and contributing to energy conservation and emission reduction, achieving the dual objectives. Attached Figure Description

[0017] Figure 1 A schematic diagram of a two-stage steam supply system for a coal-fired power unit coupled with dual-tank active solar thermal energy storage.

[0018] The labels in the attached diagram are as follows: 10. Solar energy storage subsystem; 20. Molten salt heat storage and release subsystem; 21. High-temperature molten salt tank; 22. Low-temperature molten salt tank; 30. First heat exchanger; 40. Second heat exchanger; 50. Coal-fired power unit; 51. Boiler; 52. Cylinder assembly; 521. High-pressure cylinder; 522. Intermediate-pressure cylinder; 523. Low-pressure cylinder; 53. Generator; 54. Deaerator; 55. Condenser; 56. Condensate pump; 57. Feedwater pump; 581. First high-pressure heater; 582. Second high-pressure heater; 583. Third high-pressure heater; 584. First low-pressure heater; 585. Second low-pressure heater; 586. Third low-pressure heater; 587. Fourth low-pressure heater. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the invention. The described embodiments are some, but not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0020] like Figure 1 As shown, this embodiment of the invention provides a two-stage steam supply system for a coal-fired power unit with coupled dual-tank active solar thermal energy storage, including: a solar energy storage subsystem 10, a molten salt heat storage and release subsystem 20, a first heat exchanger 30, a second heat exchanger 40, and a coal-fired power unit 50. The solar energy storage subsystem 10 is used to absorb solar energy and convert it into thermal energy. The molten salt heat storage and release subsystem 20 includes a high-temperature molten salt tank 21 and a low-temperature molten salt tank 22. The low-temperature molten salt tank 22 is connected to the low-temperature side inlet of the solar energy storage subsystem 10, and the high-temperature molten salt tank 21 is connected to the low-temperature side outlet of the solar energy storage subsystem 10. The high-temperature side inlet of the first heat exchanger 30 is connected to the outlet of the high-temperature molten salt tank 21. The high-temperature inlet of the second heat exchanger 40 is connected to the high-temperature outlet of the first heat exchanger 30, and the high-temperature outlet of the second heat exchanger 40 is connected to the inlet of the low-temperature molten salt tank 22. The coal-fired unit 50 includes a boiler 51 and a cylinder group 52. The steam outlet of the boiler 51 is connected to the steam inlet of the cylinder group 52, the steam outlet of the cylinder group 52 is connected to the steam inlet of the boiler 51, the steam outlet of the cylinder group 52 is connected to the low-temperature inlet of the first heat exchanger 30, the low-temperature outlet of the first heat exchanger 30 is connected to the steam inlet of the cylinder group 52, and the steam outlet of the cylinder group 52 is connected to the low-temperature inlet of the second heat exchanger 40. The low-temperature outlet of the second heat exchanger 40 is used for the first industrial steam supply.

[0021] Specifically, the dual-stage steam supply system of the coal-fired unit with coupled dual-tank active solar thermal energy storage includes a solar energy storage subsystem 10, a molten salt heat storage and release subsystem 20, a first heat exchanger 30, a second heat exchanger 40, and a coal-fired unit 50. The solar energy storage subsystem 10 converts solar energy into thermal energy. The low-temperature salt in the low-temperature molten salt tank 22 absorbs the heat from the solar energy storage subsystem 10 and becomes high-temperature salt. The 590°C high-temperature salt enters the first heat exchanger 30 through the high-temperature side inlet and releases heat to become 350°C medium-temperature salt. The medium-temperature salt is discharged from the high-temperature side outlet of the first heat exchanger 30. The medium-temperature salt enters the second heat exchanger 40 through the high-temperature side inlet and releases heat again to become 300°C low-temperature salt. The low-temperature salt is discharged from the high-temperature side outlet of the second heat exchanger 40 and enters the low-temperature molten salt tank 22, forming a cycle of salt absorbing and releasing heat.

[0022] The low-temperature steam discharged from the exhaust port of cylinder group 52 is transported to the low-temperature side inlet of the first heat exchanger 30. The low-temperature steam absorbs the heat released by the high-temperature salt in the first heat exchanger 30 and becomes the first high-temperature steam, which is discharged from the low-temperature side outlet of the first heat exchanger 30 to the steam inlet of cylinder group 52.

[0023] The low-temperature steam discharged from the exhaust port of cylinder group 52 is transported to the low-temperature side inlet of the second heat exchanger 40. The low-temperature steam absorbs the heat released by the medium-temperature salt in the second heat exchanger 40 and is heated to become the second high-temperature steam, which is then discharged from the low-temperature side outlet of the second heat exchanger 40 as the first industrial steam supply.

[0024] This invention relates to a dual-stage steam supply system for a coal-fired power unit with coupled dual-tank active solar thermal energy storage. The solar energy storage subsystem 10 is coupled to the coal-fired power unit 50 via a molten salt heat storage and release subsystem 20 and two heat exchangers. The energy stored in the solar energy storage subsystem 10 is stored as thermal energy in a high-temperature molten salt tank 21. The high-temperature salt in the molten salt tank 21 flows sequentially through a first heat exchanger 30 and a second heat exchanger 40, releasing heat. A portion of the low-temperature steam discharged from the cylinder assembly 52 of the coal-fired power unit 50 enters the first heat exchanger 30 to absorb the heat released by the high-temperature salt, generating high-temperature steam for use by the cylinder assembly. A portion of the low-temperature steam enters the second heat exchanger 40 to absorb the heat released by the high-temperature salt a second time, raising its temperature for use as the first industrial steam supply. By utilizing the energy of the solar energy storage subsystem 10 to heat the low-temperature steam, while meeting the grid's deep peak-shaving requirements, the system can both guarantee industrial steam supply needs and reduce the steam output from the boiler 51 of the coal-fired power unit 50, thereby reducing the coal consumption for power generation and contributing to energy conservation and emission reduction, achieving the dual objectives.

[0025] In some embodiments of the present invention, the cylinder group 52 includes a high-pressure cylinder 521, an intermediate-pressure cylinder 522, and a low-pressure cylinder 523 connected coaxially in sequence. The exhaust ports of the high-pressure cylinder 521, the intermediate-pressure cylinder 522, and the low-pressure cylinder 523 are respectively connected to the low-temperature side inlet of the first heat exchanger 30, and the low-temperature side outlet of the first heat exchanger 30 is connected to the inlet of the high-pressure cylinder 521. Specifically, the exhaust ports of the three cylinders, high-pressure cylinder 521, intermediate-pressure cylinder 522, and low-pressure cylinder 523, can be directly connected to the low-temperature side inlet of the first heat exchanger 30, or the exhaust ports of the three cylinders can be indirectly connected to the low-temperature side inlet of the first heat exchanger 30 through other components. The first heat exchanger 30 heats the low-temperature steam to generate high-temperature steam that can be used by the high-pressure cylinder 521. The high-temperature steam is discharged from the low-temperature side outlet of the first heat exchanger 30 and enters the high-pressure cylinder 521 through the inlet of the high-pressure cylinder 521. Furthermore, the steam outlet of boiler 51 is connected to the steam inlet of high-pressure cylinder 521. The high-temperature steam output from boiler 51 enters high-pressure cylinder 521 through its inlet for use. The reheat steam outlet of boiler 51 is connected to the steam inlet of intermediate-pressure cylinder 522. The reheat steam output from boiler 51 enters intermediate-pressure cylinder 522 through its inlet for use. The steam outlet of intermediate-pressure cylinder 522 is connected to the steam inlet of low-pressure cylinder 523. A portion of the steam in intermediate-pressure cylinder 522 enters low-pressure cylinder 523 through its inlet for use.

[0026] The coal-fired unit 50 also includes a generator 53, which is coaxially connected to the high-pressure cylinder 521, the intermediate-pressure cylinder 522 and the low-pressure cylinder 523. The generator 53 converts mechanical energy into electrical energy through the operation of the high-pressure cylinder 521, the intermediate-pressure cylinder 522 and the low-pressure cylinder 523.

[0027] In some embodiments of the present invention, the coal-fired unit 50 further includes a deaerator 54. The exhaust ports of the high-pressure cylinder 521, the intermediate-pressure cylinder 522, and the low-pressure cylinder 523 are respectively connected to the deaerator 54. The deaerator 54 is connected to the low-temperature side inlet of the first heat exchanger 30. The exhaust ports of the three cylinders, high-pressure cylinder 521, intermediate-pressure cylinder 522, and low-pressure cylinder 523, are connected to the deaerator 54 to remove oxygen and other non-condensable gases (such as carbon dioxide) from the solution in the low-temperature steam discharged from the three cylinders, preventing equipment corrosion; at the same time, it heats the feedwater and improves the system thermal efficiency.

[0028] In some embodiments of the present invention, the deaerator 54 is connected to the low-temperature side inlet of the second heat exchanger 40. Specifically, the steam outlet of the deaerator 54 is connected to the low-temperature side inlet of the second heat exchanger 40, and the deaerated low-temperature steam enters the second heat exchanger 40 to absorb the heat released by the molten salt in the second heat exchanger 40 and generate high-temperature steam for use as the first industrial steam supply.

[0029] In some embodiments of the present invention, the deaerator 54 is connected to the steam inlet of the boiler 51. Specifically, the steam outlet of the deaerator 54 is also connected to the steam inlet of the boiler 51 to supply water to the boiler 51.

[0030] The steam outlet of deaerator 54 is connected to the low-temperature inlet of the first heat exchanger 30, the low-temperature inlet of the second heat exchanger 40, and the steam inlet of boiler 51, respectively. This means the low-temperature steam from the deaerator 54 outlet is divided into three streams that enter boiler 51, the first heat exchanger 30, and the second heat exchanger 40. Because the molten salt flowing through the first heat exchanger 30 has a higher temperature and releases more heat, the low-temperature steam entering the first heat exchanger 30 absorbs a significant amount of heat released by the high-temperature salt, thus heating up to become high-temperature steam usable by high-pressure cylinder 521. Since the high-temperature salt releases some heat in the first heat exchanger 30, becoming medium-temperature salt, and its temperature is higher than that of the low-temperature steam, the low-temperature steam enters the second heat exchanger 40 and absorbs the heat from the medium-temperature salt, heating up to become higher-temperature steam for use as the first industrial steam supply. The low-temperature steam output from the deaerator 54 outlet to boiler 51 is heated by boiler 51 to generate high-temperature steam usable by high-pressure cylinder 521.

[0031] In some embodiments of the present invention, the coal-fired unit 50 further includes a high-pressure heater, wherein the exhaust port of the high-pressure cylinder 521 and the exhaust port of the intermediate-pressure cylinder 522 are respectively connected to the high-temperature side inlet of different high-pressure heaters, the high-temperature side outlet of the high-pressure heater is connected to the inlet of the deaerator 54, the outlet of the deaerator 54 is connected to the low-temperature side inlet of the high-pressure heater, and the low-temperature side outlet of the high-pressure heater is connected to the steam inlet of the boiler 51. Specifically, in this embodiment, there are three high-pressure heaters. The first exhaust port of the high-pressure cylinder 521 is connected to the high-temperature side inlet of the first high-pressure heater 581, the second exhaust port of the high-pressure cylinder 521 is connected to the high-temperature side inlet of the second high-pressure heater 582, the first exhaust port of the intermediate-pressure cylinder 522 is connected to the high-temperature side inlet of the third high-pressure heater 583, the high-temperature side outlet of the first high-pressure heater 581 is connected to the high-temperature side inlet of the second high-pressure heater 582, and the high-temperature side outlet of the second high-pressure heater 582 is connected to the high-temperature side inlet of the third high-pressure heater 583. The second exhaust port of the intermediate-pressure cylinder 522 is connected to the inlet of the deaerator 54. The outlet of deaerator 54 is connected to the low-temperature side inlet of the third high-pressure heater 583. The low-temperature side outlet of the third high-pressure heater 583 is connected to the low-temperature side inlet of the second high-pressure heater 582. The low-temperature side outlet of the second high-pressure heater 582 is connected to the low-temperature side inlet of the first high-pressure heater 581. The low-temperature side outlet of the first high-pressure heater 581 is connected to the steam inlet of boiler 51. The low-temperature side outlet of the first high-pressure heater 581 is also connected to the low-temperature side inlet of the first heat exchanger 30. A feedwater pump 57 can also be installed between deaerator 54 and the third high-pressure heater 583 to pump the low-temperature steam output from deaerator 54 into the third high-pressure heater 583, providing a certain flow force.

[0032] The flow path of the low-temperature steam at the first exhaust port of the high-pressure cylinder 521 is as follows: high-temperature side inlet of the first high-pressure heater 581 → high-temperature side outlet of the first high-pressure heater 581 → high-temperature side inlet of the second high-pressure heater 582 → high-temperature side outlet of the second high-pressure heater 582 → high-temperature side inlet of the third high-pressure heater 583 → high-temperature side outlet of the third high-pressure heater 583 → inlet of the deaerator 54 → outlet of the deaerator 54 → low-temperature side inlet of the third high-pressure heater 583 → low-temperature side outlet of the third high-pressure heater 583 → low-temperature side inlet of the second high-pressure heater 582 → low-temperature side outlet of the second high-pressure heater 582 → low-temperature side inlet of the first high-pressure heater 581 → low-temperature side outlet of the first high-pressure heater 581 → steam inlet of the boiler 51 or low-temperature side inlet of the first heat exchanger 30.

[0033] The low-temperature steam from the second exhaust port of high-pressure cylinder 521 is divided into three branches. The first branch connects to the high-temperature side inlet of the second high-pressure heater 582, the second branch connects to the reheat steam inlet of boiler 51, and the third branch serves as the second industrial steam supply. The low-temperature steam in the first branch originates from the high-temperature side inlet of the second high-pressure heater 582, and the remaining portion follows the same low-temperature steam path as the first exhaust port of high-pressure cylinder 521. The first exhaust port of intermediate-pressure cylinder 522 originates from the high-temperature side inlet of the third high-pressure heater 583, and the remaining portion follows the same low-temperature steam path as the first exhaust port of high-pressure cylinder 521.

[0034] In some embodiments of the present invention, the coal-fired unit 50 further includes a low-pressure heater and a condenser. Multiple exhaust ports of the low-pressure cylinder 523 are connected to the high-temperature side inlet of the low-pressure heater, the high-temperature side outlet of the low-pressure heater is connected to the inlet of the condenser 55, one exhaust port of the low-pressure cylinder 523 is connected to the inlet of the condenser 55, the outlet of the condenser 55 is connected to the low-temperature side inlet of the low-pressure heater, and the low-temperature side outlet of the low-pressure heater is connected to the deaerator 54. In this embodiment, the low-pressure cylinder 523 has five exhaust ports, one of which is connected to the inlet of the condenser 55, and the other four are connected to the corresponding four low-pressure heaters. The first exhaust port of low-pressure cylinder 523 is connected to the high-temperature side inlet of the first low-pressure heater 584; the second exhaust port of low-pressure cylinder 523 is connected to the high-temperature side inlet of the second low-pressure heater 585; the third exhaust port of low-pressure cylinder 523 is connected to the high-temperature side inlet of the third low-pressure heater 586; the fourth exhaust port of low-pressure cylinder 523 is connected to the high-temperature side inlet of the fourth low-pressure heater 587; the high-temperature side outlet of the first low-pressure heater 584 is connected to the high-temperature side inlet of the second low-pressure heater 585; the high-temperature side outlet of the second low-pressure heater 585 is connected to the high-temperature side inlet of the third low-pressure heater 586; and the high-temperature side outlet of the third low-pressure heater 586... The high-temperature side outlet of the fourth low-pressure heater 587 is connected to the high-temperature side inlet of the fourth low-pressure heater 587. The high-temperature side outlet of the fourth low-pressure heater 587 is connected to the inlet of the condenser 55. The outlet of the condenser 55 is connected to the low-temperature side inlet of the fourth low-pressure heater 587 via the condensate pump 56. The low-temperature side outlet of the fourth low-pressure heater 587 is connected to the low-temperature side inlet of the third low-pressure heater 586. The low-temperature side outlet of the third low-pressure heater 586 is connected to the low-temperature side inlet of the second low-pressure heater 585. The low-temperature side outlet of the second low-pressure heater 585 is connected to the low-temperature side inlet of the first low-pressure heater 584. The low-temperature side outlet of the first low-pressure heater 584 is connected to the inlet of the deaerator 54.

[0035] The flow path of the low-temperature steam at the first exhaust port of the low-pressure cylinder 523 is as follows: high-temperature side inlet of the first low-pressure heater 584 → high-temperature side outlet of the first low-pressure heater 584 → high-temperature side inlet of the second low-pressure heater 585 → high-temperature side outlet of the second low-pressure heater 585 → high-temperature side inlet of the third low-pressure heater 586 → high-temperature side outlet of the third low-pressure heater 586 → high-temperature side inlet of the fourth low-pressure heater 587 → high-temperature side outlet of the fourth low-pressure heater 587 → inlet of the condenser 55 → outlet of the condenser 55 → inlet of the condensate pump 56 → outlet of the condensate pump 56 → low-temperature side inlet of the fourth low-pressure heater 587 → low-temperature side outlet of the fourth low-pressure heater 587 → third low-pressure heater 584 → high-temperature side outlet of the third low-pressure heater 585 → high-temperature side outlet of the fourth low-pressure heater 587 → high-temperature side outlet of the third low-pressure heater 585 → high-temperature side outlet of the third low-pressure heater 585 → high-temperature side outlet of the fourth ... fourth low-pressure heater 585 → high-temperature side outlet of the third low-pressure heater 585 Low-temperature side inlet of heater 586 → Low-temperature side outlet of third low-pressure heater 586 → Low-temperature side inlet of second low-pressure heater 585 → Low-temperature side outlet of second low-pressure heater 585 → Low-temperature side inlet of first low-pressure heater 584 → Low-temperature side outlet of first low-pressure heater 584 → Inlet of deaerator 54 → Outlet of deaerator 54 → Low-temperature side inlet of third high-pressure heater 583 → Low-temperature side outlet of third high-pressure heater 583 → Low-temperature side inlet of second high-pressure heater 582 → Low-temperature side outlet of second high-pressure heater 582 → Low-temperature side inlet of first high-pressure heater 581 → Low-temperature side outlet of first high-pressure heater 581 → Steam inlet of boiler 51 or low-temperature side inlet of first heat exchanger 30.

[0036] In some embodiments of the present invention, the exhaust port of the high-pressure cylinder 521 includes a high-temperature exhaust port and a low-temperature exhaust port, that is, the first exhaust port is a low-temperature exhaust port and the second exhaust port is a high-temperature exhaust port. The high-temperature exhaust port and the low-temperature exhaust port are respectively connected to the deaerator 54, the high-temperature exhaust port is connected to the reheat steam inlet of the boiler 51, the reheat steam outlet of the boiler 51 is connected to the steam inlet of the intermediate-pressure cylinder 522, and the high-temperature exhaust port is used for the second industrial steam supply. The high-temperature steam discharged from the high-pressure cylinder 521 is discharged through the high-temperature exhaust port. The first part of the high-temperature steam is used as the second industrial steam supply, the second part of the high-temperature steam enters the reheat steam inlet of the boiler 51, is heated by the reheater of the boiler 51, and is discharged through the reheat exhaust port, and the third part of the high-temperature steam enters the second high-pressure heater 582.

[0037] In some embodiments of the present invention, the pressure of the industrial steam output from the high-temperature exhaust port is different from the pressure of the industrial steam output from the low-temperature side outlet of the second heat exchanger 40. The steam output from the high-temperature exhaust port is used as the second industrial steam supply, and the steam output from the low-temperature side outlet of the second heat exchanger 40 is used as the first industrial steam supply. The steam pressures of the first industrial steam supply and the second industrial steam supply are different to achieve different industrial applications.

[0038] In some embodiments of the present invention, the pressure of the industrial steam output from the high-temperature exhaust port is 1.5 MPa, that is, the pressure of the second industrial steam supply is 1.5 MPa.

[0039] In some embodiments of the present invention, the pressure of the steam output from the low-temperature side outlet of the second heat exchanger 40 is 3 MPa, that is, the pressure of the first industrial steam supply is 3 MPa.

[0040] In some embodiments of the present invention, the temperature of the steam output from the low-temperature side outlet of the second heat exchanger 40 is 300°C, that is, the temperature of the first industrial steam supply is 300°C.

[0041] The molten salt heat storage and release subsystem 20 provides a portion of the main steam Q1, and the boiler 51 provides Q2. Considering the overheating limit of the boiler 51 reheater, the amount of cold reheat steam that can be extracted is Q1 + r × Q2 (where r is the allowable extraction coefficient, generally 5%~8%). Corresponding to the conventional cogeneration boiler 51 supplying steam, when the main steam provided by boiler 51 is Q1 + Q2, considering the overheating limit of boiler 51 reheater, the amount of cold reheat steam that can be extracted is r × (Q1 + Q2) (where r is the allowable extraction coefficient). In summary, with the same amount of main steam entering the high-pressure cylinder 521, this invention proposes a system with a larger cold reheat extraction capacity, increasing the extraction capacity by (1-r) × Q1. After the molten salt heat storage and release subsystem 20 is coupled with the coal-fired unit 50, the molten salt heat storage and release subsystem 20 removes the limitation of the boiler 51 reheater on the amount of steam extracted by sharing the heating load. Thus, under the same main steam consumption, the actual steam extraction heating capacity of the unit is greatly improved, thereby achieving "thermal-electric decoupling" more efficiently.

[0042] The dual-tank active solar thermal energy storage dual-stage steam supply system for coal-fired power units in this embodiment of the invention can reduce the coal consumption for power generation by 10~20g / kWh for conventional 350MW supercritical units; at the same time, it can provide large-flow industrial steam at two pressure levels, meeting the unit's thermoelectric decoupling requirements.

[0043] 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 two-stage steam supply system for a coal-fired power unit with coupled dual-tank active solar thermal energy storage, characterized in that, include: A solar energy storage subsystem, wherein the solar energy storage subsystem is used to absorb solar energy and convert solar energy into thermal energy; A molten salt heat storage and release subsystem includes a high-temperature molten salt tank and a low-temperature molten salt tank. The low-temperature molten salt tank is connected to the low-temperature side inlet of the solar energy storage subsystem, and the high-temperature molten salt tank is connected to the low-temperature side outlet of the solar energy storage subsystem. The first heat exchanger has its high-temperature side inlet connected to the outlet of the high-temperature molten salt tank. The second heat exchanger has its high-temperature side inlet connected to the high-temperature side outlet of the first heat exchanger, and its high-temperature side outlet connected to the inlet of the low-temperature molten salt tank. A coal-fired power unit, comprising a boiler and a cylinder assembly, wherein the steam outlet of the boiler is connected to the steam inlet of the cylinder assembly, the steam outlet of the cylinder assembly is connected to the steam inlet of the boiler, the steam outlet of the cylinder assembly is connected to the low-temperature side inlet of a first heat exchanger, the low-temperature side outlet of the first heat exchanger is connected to the steam inlet of the cylinder assembly, and the steam outlet of the cylinder assembly is connected to the low-temperature side inlet of a second heat exchanger, the low-temperature side outlet of the second heat exchanger being used for first industrial steam supply.

2. The dual-stage steam supply system for coal-fired power units with coupled dual-tank active solar thermal energy storage as described in claim 1, characterized in that, The pressure of the steam output from the low-temperature side outlet of the second heat exchanger is 3 MPa.

3. The two-stage steam supply system for coal-fired power units with coupled dual-tank active solar thermal energy storage as described in claim 1, characterized in that, The temperature of the steam output from the low-temperature side outlet of the second heat exchanger is 300°C.

4. The dual-stage steam supply system for coal-fired power units with coupled dual-tank active solar thermal energy storage as described in claim 1, characterized in that, The cylinder assembly includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder connected coaxially in sequence. The exhaust ports of the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder are respectively connected to the low-temperature side inlet of the first heat exchanger, and the low-temperature side outlet of the first heat exchanger is connected to the inlet of the high-pressure cylinder.

5. The dual-stage steam supply system for coal-fired power units with coupled dual-tank active solar thermal energy storage as described in claim 4, characterized in that, The coal-fired unit also includes a deaerator. The exhaust ports of the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder are respectively connected to the deaerator. The deaerator is connected to the low-temperature side inlet of the first heat exchanger.

6. The dual-stage steam supply system for coal-fired power units with coupled dual-tank active solar thermal energy storage as described in claim 5, characterized in that, The deaerator is connected to the low-temperature side inlet of the second heat exchanger.

7. The two-stage steam supply system for a coal-fired power unit with coupled dual-tank active solar thermal energy storage as described in claim 5, characterized in that, The deaerator is connected to the steam inlet of the boiler.

8. The two-stage steam supply system for a coal-fired unit with coupled dual-tank active solar thermal energy storage as described in claim 5, characterized in that, The exhaust port of the high-pressure cylinder includes a high-temperature exhaust port and a low-temperature exhaust port. The high-temperature exhaust port and the low-temperature exhaust port are respectively connected to the deaerator. The high-temperature exhaust port is connected to the reheat steam inlet of the boiler. The reheat steam outlet of the boiler is connected to the steam inlet of the intermediate-pressure cylinder. The high-temperature exhaust port is used for secondary industrial steam supply.

9. The two-stage steam supply system for a coal-fired unit with coupled dual-tank active solar thermal energy storage as described in claim 8, characterized in that, The pressure of the industrial steam output from the high-temperature exhaust port is different from the pressure of the industrial steam output from the low-temperature side outlet of the second heat exchanger.

10. The two-stage steam supply system for a coal-fired unit with coupled dual-tank active solar thermal energy storage as described in claim 9, characterized in that, The pressure of the industrial steam output from the high-temperature exhaust port is 1.5 MPa.

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