Boiler complementary multistage steam supply system coupled with thermocline solar photo-thermal energy storage

Abstract

The invention provides a boiler complementary multi-stage steam supply system coupled with thermocline solar photo-thermal energy storage. The boiler complementary multi-stage steam supply system comprises a solar storage system, a thermal power heat supply system and a steam supply system. The solar storage system comprises a solar tower, a fused salt storage heat exchanger, a thermocline heat storage tank, a main heat exchanger and a multi-stage heater; the solar tower is respectively connected with the fused salt storage heat exchanger and the main heat exchanger, the fused salt storage heat exchanger is respectively connected with the thermocline heat storage tank and the main heat exchanger, and the main heat exchanger is connected with the multi-stage heater; the thermal power heat supply system comprises a boiler, a regenerative system and a steam turbine, water supply ports of the boiler and the regenerative system are connected with a water inlet of the multi-stage heater, and a steam outlet of the multi-stage heater and a steam outlet of the boiler are connected with a steam inlet of the steam turbine; the multi-stage heater and the steam outlet of the boiler are connected with a steam supply system, under the condition that the deep peak regulation requirement of a power grid is met, the industrial steam supply requirement can be guaranteed, and the power generation coal consumption of a unit can be reduced.

Description

Technical Field

[0001] This disclosure belongs to the field of energy utilization technology, specifically relating to a boiler complementary multi-stage steam supply system coupled with thermotropic solar thermal energy storage. Background Technology

[0002] With the increasing proportion of renewable energy sources such as wind and solar power, their intermittent and fluctuating characteristics present 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. Among these, 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 industrial parameters 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 it requires the use of a main steam back-pressure turbine for heating, and also requires the construction of a back-pressure turbine plant, the purchase of back-pressure turbines and related valves, resulting in high upfront investment costs, especially when steam supply demand fluctuates, leading to unstable economic returns. Summary of the Invention

[0004] This disclosure aims to at least solve one of the technical problems existing in the prior art, and to provide a boiler complementary multi-stage steam supply system that couples thermotropic solar thermal energy storage.

[0005] One aspect of this disclosure proposes a boiler-complementary multi-stage steam supply system coupled with spherical solar thermal energy storage, the system comprising: a solar energy storage system, a thermal power heating system, and a steam supply system; wherein, The solar energy storage system includes a solar tower, a molten salt storage heat exchanger, a thermocline storage tank, a main heat exchanger, and a multi-stage heater. The solar tower is connected to the molten salt storage heat exchanger and the main heat exchanger, respectively. The molten salt storage heat exchanger is connected to the inclined temperature layer heat storage tank and the main heat exchanger, respectively. The main heat exchanger is connected to the multi-stage heater. The thermal power heating system includes a boiler, a regenerative system, and a steam turbine. The feedwater inlets of the boiler and the regenerative system are connected to the inlets of the multi-stage heaters. The steam outlets of the multi-stage heaters and the boiler are connected to the steam inlets of the steam turbines. The multi-stage heater is connected to the steam outlet of the boiler via the steam supply system.

[0006] Optionally, the inclined thermosphere thermal storage tank includes a high-temperature molten salt storage section located in the upper region and a low-temperature molten salt storage section located in the lower region; The high-temperature molten salt storage section and the low-temperature molten salt storage section are both connected to the molten salt storage heat exchanger. The high-temperature molten salt storage section stores high-temperature molten salt, and the low-temperature molten salt storage section stores low-temperature molten salt. When solar radiation is insufficient, the high-temperature molten salt in the high-temperature molten salt storage section enters the molten salt storage heat exchanger to release heat. The molten salt medium in the main heat exchanger absorbs heat in the molten salt storage heat exchanger and releases heat in the main heat exchanger to provide heat to the multi-stage heater.

[0007] Optionally, the multi-stage heater includes a first-stage heater, and the steam turbine includes a high-pressure cylinder, wherein... The molten salt outlet of the main heat exchanger is connected to the molten salt inlet of the first-stage heater; The inlet of the first-stage heater is connected to the regenerative system and the feedwater of the boiler. The main steam outlet of the first-stage heater and the main steam outlet of the boiler are connected to the main steam inlet of the high-pressure cylinder through the main steam pipeline.

[0008] Optionally, the steam supply system includes a main steam supply pipeline connected to the main steam pipeline for providing industrial steam at a pressure of 3-24 MPa.

[0009] Optionally, the cold resteam outlet of the high-pressure cylinder is connected to the cold resteam inlet of the boiler via a cold resteam pipeline; wherein, The steam supply system includes a cold reheat industrial steam supply pipeline connected to a cold reheat steam pipeline for providing industrial steam at a pressure of 1.5 MPa.

[0010] Optionally, the multi-stage heater further includes a second-stage heater, and the steam turbine includes an intermediate-pressure cylinder; wherein, The molten salt inlet of the second-stage heater is connected to the molten salt outlet of the main heat exchanger. The hot resteam outlet of the second-stage heater is connected to the hot resteam outlet of the boiler and the hot resteam inlet of the intermediate-pressure cylinder through a hot resteam pipeline. The second-stage heater is also connected to the regenerative system and the feedwater inlet of the boiler.

[0011] Optionally, the steam supply system includes a hot resteam supply pipeline connected to the hot resteam pipeline for providing industrial steam at a pressure of 1.5 MPa.

[0012] Optionally, the multi-stage heater further includes a third-stage heater, the molten salt inlet of which is connected to the molten salt outlets of the first-stage heater and the second-stage heater respectively, the molten salt outlet of which is connected to the main heat exchanger, and the third-stage heater is also connected to the feedwater inlet of the regenerative system.

[0013] Optionally, the steam supply system includes a molten salt industrial steam supply line connected to the steam supply line of the third-stage heater for providing industrial steam at a pressure of 1.5 MPa.

[0014] Another aspect of this disclosure proposes a steam supply method for a boiler-complementary multi-stage steam supply system coupled with spherical solar thermal energy storage as described above, the steam supply method comprising: Solar heat is collected by a solar tower. Under sufficient sunlight, part of the high-temperature molten salt coming out of the solar tower enters the molten salt storage heat exchanger, and the other part enters the main heat exchanger to provide heat to the multi-stage heater. When solar radiation is insufficient, the high-temperature molten salt in the thermocline storage tank enters the molten salt storage heat exchanger to release heat. The molten salt medium in the main heat exchanger absorbs heat in the molten salt storage heat exchanger and releases heat in the main heat exchanger to provide heat to the multi-stage heater. The high-temperature molten salt from the main heat exchanger, along with the low-temperature water from the boiler and the regenerative system, enters the multi-stage heater. The low-temperature water in the multi-stage heater absorbs the heat from the high-temperature molten salt to form steam, which, along with the steam generated by the boiler, flows into the steam turbine. At the same time, some of the steam also forms industrial steam.

[0015] This disclosure proposes a boiler-complementary multi-stage steam supply system coupled with thermotropic solar thermal energy storage, which has the following beneficial effects: (1) This invention creatively combines tower solar thermal energy storage with traditional coal-fired power units to form a steam production system that complements solar thermal energy and coal-fired boilers, thus achieving an organic combination of the advantages of clean and low-carbon new energy and continuous and reliable coal power. (2) This disclosure combines multi-stage heating of condensate into superheated steam for industrial steam supply, realizing multi-stage energy utilization of the thermal system; (3) This disclosure provides the main steam of the unit by a multi-stage heater, which can significantly increase the cold resteam heating flow rate and reduce the heating energy consumption; (4) The system disclosed herein can provide industrial steam supply for all pressure requirements within the range of 1.5MPa to 24MPa. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a boiler complementary multi-stage steam supply system with coupled thermotropic layer solar thermal energy storage according to Embodiment 1 of this disclosure. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure 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 used to explain this disclosure and represent a part of the embodiments of this disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the protection scope of this disclosure.

[0018] Example 1 like Figure 1 As shown in the example, this example presents a boiler complementary multi-stage steam supply system coupled with thermotropic solar thermal energy storage, including: a solar energy storage system, a thermal power heating system, and a steam supply system.

[0019] Please continue to refer to the following: Figure 1 The solar energy storage system 110 includes a solar tower 111, a molten salt storage heat exchanger 112, a thermocline storage tank 113, a main heat exchanger 114, and a multi-stage heater, which includes a first-stage heater 115, a second-stage heater 116, and a third-stage heater 117.

[0020] For further information, please continue to refer to [link / reference]. Figure 1 The molten salt outlet of the solar tower 111 is connected to the molten salt inlet of the molten salt storage heat exchanger 112 and the molten salt inlet of the main heat exchanger 114. The molten salt storage heat exchanger 112 is also connected to the inclined thermosphere heat storage tank 113 and the main heat exchanger 114. Furthermore, the molten salt outlet of the main heat exchanger 114 is connected to the molten salt inlets of the first-stage heater 115 and the second-stage heater 116. The molten salt inlet of the main heat exchanger 114 is connected to the molten salt outlet of the third-stage heater 117. The molten salt inlet of the third-stage heater 117 is also connected to the molten salt outlets of the first-stage heater 115 and the second-stage heater 116, forming a molten salt circuit.

[0021] Based on the above structure, under sufficient sunlight, part of the high-temperature molten salt coming out of the solar tower enters the molten salt storage heat exchanger to heat the molten salt in the hydrothermal storage tank, and part enters the main heat exchanger to supply the heat exchange required by the first-stage heater, the second-stage heater, and the third-stage heater.

[0022] It should also be noted that the inclined thermosphere thermal storage tank is mainly used for storing heat. In situations where sunlight is insufficient, the molten salt in the tank is used to provide heat to the main heat exchanger. For example, the inclined thermosphere thermal storage tank includes a high-temperature molten salt storage section in the upper region and a low-temperature molten salt storage section in the lower region. Both the high-temperature and low-temperature molten salt storage sections are connected to a molten salt storage and release heat exchanger. The high-temperature molten salt storage section stores high-temperature molten salt, and the low-temperature molten salt storage section stores low-temperature molten salt. In other words, solar heat is stored in the inclined thermosphere thermal storage tank through the molten salt storage and release heat exchanger, with the high-temperature molten salt stored above the tank and the low-temperature molten salt stored below. During the heat storage process, the molten salt flows out from below the tank, absorbs heat through the molten salt storage and release heat exchanger, and then enters the upper part of the tank. In this way, when solar radiation is insufficient, the high-temperature molten salt at the top of the thermocline storage tank releases heat into the molten salt storage heat exchanger, and then enters the low-temperature molten salt side at the bottom of the thermocline. The molten salt medium in the molten salt storage heat exchanger absorbs heat in the main heat exchanger and then releases heat in the main heat exchanger to supply the heat exchange required by the first-stage heater, the second-stage heater, and the third-stage heater.

[0023] Furthermore, please continue to refer to... Figure 1 The thermal power heating system includes a boiler 121, which generates high-temperature and high-pressure steam by burning fuel (such as coal) to power the steam turbine.

[0024] Furthermore, please continue to refer to... Figure 1 The thermal power heating system also includes a regenerative system, which raises the feedwater temperature and improves thermal efficiency through multi-stage high-pressure and low-pressure heaters. The regenerative system includes a deaerator 122-1, a feedwater pump 122-2, a first high-pressure heater 122-3, a second high-pressure heater 122-4, a third high-pressure heater 122-5, a first low-pressure heater 122-6, a second low-pressure heater 122-7, a third low-pressure heater 122-8, a fourth low-pressure heater 122-9, a condensate pump 122-10, and a condenser 122-11.

[0025] Furthermore, please continue to refer to... Figure 1 The thermal power heating system also includes a steam turbine, which converts steam thermal energy into mechanical energy to drive a generator to generate electricity. The steam turbine includes a high-pressure cylinder 123-1, an intermediate-pressure cylinder 123-2, and a low-pressure cylinder 123-3.

[0026] For further information, please continue to refer to [link / reference]. Figure 1 The thermal power heating system also includes generator 124.

[0027] Based on the above structure, such as Figure 1As shown, the connection between the thermal power heating system and the solar energy storage system is as follows: The main steam outlet of the first-stage heater 115 and the main steam outlet of the boiler 121 are connected to the main steam inlet of the high-pressure cylinder 123-1 through the main steam pipeline a. Simultaneously, the feedwater inlet of the boiler 121 is connected to the inlet of the first-stage heater 115 through the first feedwater pipeline b. That is, the boiler inlet feedwater absorbs heat in the first-stage heat exchanger to form high-temperature, high-pressure steam, which then flows into the unit's main steam system. Simultaneously, the condensate from the feedwater pump outlet is pressurized, absorbs heat in the first-stage heater, and forms high-temperature steam, which then flows into the unit's reheat steam system. This steam production process forms a complementary steam system of solar thermal and coal-fired boiler. In addition, a main steam supply pipeline 131 is installed on the main steam pipeline a to provide industrial steam at a pressure of 3-24 MPa. That is, high-pressure industrial steam is supplied by drawing main steam from the molten salt system and the coal-fired boiler outlet; this point can provide industrial steam at pressures of 3 MPa and above.

[0028] Meanwhile, the cold reheat steam outlet of the high-pressure cylinder 123-1 is also connected to the cold reheat steam inlet of the boiler 121 via cold reheat steam pipeline c. The low-temperature reheat steam (cold reheat steam) discharged from the high-pressure cylinder returns to the boiler reheater through the cold reheat steam pipeline, is reheated into high-temperature hot reheat steam, and then sent to the intermediate-pressure cylinder to continue working, improving steam utilization efficiency. Simultaneously, a cold reheat industrial steam supply pipeline 132 is installed on the cold reheat steam pipeline c, used to provide 1.5MPa-level steam to the industrial steam supply system. In other words, a portion of the steam is drawn from the unit's cold reheat steam pipeline for 1.5MPa-level industrial steam supply.

[0029] It should be noted that, since the first-stage heater provides a portion of the main steam Q1 and the boiler provides Q2, considering the boiler reheater overheating limit, the amount of cold reheat steam that can be extracted is Q1 + r × Q2 (where r is the allowable extraction coefficient, typically 5% to 8%). Corresponding to conventional cogeneration boiler steam supply, when the boiler provides Q1 + Q2 of main steam, considering the boiler reheater overheating limit, 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 turbine high-pressure cylinder, this embodiment proposes a larger cold reheat steam extraction capacity, increasing the extraction capacity by (1-r) × Q1.

[0030] Please continue to refer to this. Figure 1As shown, the high-pressure cylinder in this embodiment is also connected to the first high-pressure heater 122-3 and the second high-pressure heater 122-4 through the steam extraction pipeline. The first high-pressure heater 122-3 and the second high-pressure heater 122-4 are connected in series on the second feedwater pipeline d between the outlet of the feedwater pump 122-2 and the inlet of the boiler 121. Of course, the second feedwater pipeline d is also connected to the first stage heater 115. In this way, the water discharged from the high-pressure cylinder is heated by the first high-pressure heater and the second high-pressure heater and then transferred to the boiler feedwater, reducing the boiler's fuel consumption.

[0031] Please continue to refer to this. Figure 1 As shown, the hot resteam outlet of the second-stage heater 116 and the hot resteam outlet of the boiler 121 are connected to the hot resteam inlet of the intermediate-pressure cylinder 123-2 via hot resteam pipeline e. Simultaneously, a hot resteam supply pipeline 133 is also connected to the hot resteam pipeline e to supply 1.5 MPa steam to the industrial system. In other words, by extracting the hot resteam collected from the outlets of the second-stage heater and the coal-fired boiler, this location can provide industrial steam at a pressure of 1.5 MPa.

[0032] Please continue to refer to this. Figure 1 As shown, the intermediate pressure cylinder 123-2 is also connected to the third high pressure heater 122-5 and the deaerator 122-1 through the steam extraction pipeline. A feed water pump 122-2 is installed between the deaerator 122-1 and the third high pressure heater 122-5. Of course, the third high pressure heater 122-5, the feed water pump 122-2 and the deaerator 122-1 are also connected to the second feed water pipeline d to heat the feed water and increase the temperature of the feed water flowing into the boiler.

[0033] It should be noted that, in addition to being connected to the second feedwater pipeline, the deaerator is also connected to the inlet of the third-stage heater 117 and the inlet of the second-stage heater 116 via the third feedwater pipeline f. In other words, the feedwater treated by the deaerator will be pressurized by the feedwater pump and then delivered to different systems via two main paths to achieve the dual functions of "boiler steam supplement" and "industrial steam supply". One path supplies the boiler and the first-stage heater. The pressurized high-pressure feedwater is sent to the boiler through the second feedwater pipeline and is finally heated into high-temperature and high-pressure main steam. At the same time, the high-pressure feedwater is also sent to the first-stage heater, where it absorbs the heat of the high-temperature molten salt to form high-temperature and high-pressure steam, which merges with the main steam generated by the boiler and flows into the high-pressure cylinder. Another route supplies the third-stage heater. The pressurized high-pressure feedwater is sent to the third-stage heater through the third feedwater pipeline. After absorbing the heat of the high-temperature molten salt, it is heated to the parameters of 3MPa and 280℃ for industrial steam supply. This route of high-pressure feedwater is also sent to the second-stage heater, where it absorbs the heat of the high-temperature molten salt to form hot reheat steam, which merges with the hot reheat steam of the boiler and flows into the intermediate-pressure cylinder.

[0034] For further information, please continue to refer to [link / reference]. Figure 1 The third-stage heater 117 is also connected to a molten salt industrial steam supply pipeline 134, which is used to supply 3MPa, 300℃ steam to the industry. That is to say, the condensate from the deaerator is pressurized by a water pump and then absorbs heat in the second-stage heater to form 3MPa-level industrial steam for external heating.

[0035] It should be noted that the main steam supply pipeline 131, the cold reheat industrial steam supply pipeline 132, the hot reheat steam supply pipeline 133, and the molten salt industrial steam supply pipeline 134 together constitute the steam supply system. This means that the system in this embodiment simultaneously has a molten salt industrial steam supply system, a cold reheat industrial steam supply system, a main steam supply system, and a hot reheat steam supply system, which are used to provide industrial steam supply for different needs.

[0036] Furthermore, please continue to refer to... Figure 1 The intermediate pressure cylinder 123-2 is connected to the low pressure cylinder 123-3 through a connecting pipe, and the energy is transmitted to the low pressure cylinder. The low pressure cylinder undergoes "multi-stage expansion", which drives the low pressure cylinder rotor to rotate and drives the generator to generate electricity.

[0037] Furthermore, such as Figure 1 As shown, the low-pressure cylinder 123-3 is connected to the generator 124 and is coaxial with the rotors of the high-pressure cylinder and the intermediate-pressure cylinder, jointly driving the generator rotor to rotate and converting the mechanical energy generated by the steam in the low-pressure cylinder into electrical energy. Additionally, the low-pressure cylinder 123-3 is connected to the condenser 122-11 via an exhaust pipe. The exhaust steam discharged from the low-pressure cylinder 123-3 condenses into condensate in the condenser 122-11. The condensate outlet at the bottom of the condenser 122-11 is connected to the condensate pump 122-10. The condensate pump 122-10 is connected to the deaerator 122-1 via the fourth feedwater pipeline h. The fourth feedwater pipeline h is equipped with a first low-pressure heater 122-6, a second low-pressure heater 122-7, a third low-pressure heater 122-8, and a fourth low-pressure heater 122-9. The condensate is pressurized by the condensate pump 122-10 and delivered to each low-pressure heater for heating.

[0038] It should be further noted that the molten salt temperature at the outlet of the main heat exchanger is generally 590℃, while the main steam and hot reheat steam temperatures under THA conditions are both 566℃. The design based on the first-stage heater enables the replacement of the boiler to provide part of the main steam. Additionally, the third-stage heater outputs a cryogenic molten salt temperature of 300℃ to the cryogenic tank.

[0039] This implementation method utilizes the synergistic effect of a solar energy storage system and a thermal power heating system to form a complementary steam system of solar thermal energy and coal-fired boilers. On the one hand, it provides heat to the steam turbine, and on the other hand, it provides industrial steam of different grades, forming a molten salt industrial steam supply system, a cold reheat industrial steam supply system, a main steam supply system, and a hot reheat steam supply system. This not only enables multi-level utilization of solar energy, but also ensures the industrial steam supply demand under deep peak shaving conditions of the unit, thereby achieving energy conservation and emission reduction.

[0040] Example 2 This example illustrates a steam supply method for a boiler-complementary multi-stage steam supply system coupled with thermotropic solar thermal energy storage. The specific process is as follows: (1) Solar heat is collected using a solar tower. Under sufficient sunlight, a portion of the high-temperature molten salt exiting the solar tower enters a molten salt storage heat exchanger. The solar heat is then stored in a thermocline heat storage tank, with the high-temperature molten salt stored above the thermocline heat storage tank and the low-temperature molten salt stored below it. During the heat storage process, the molten salt flows out from below the thermocline heat storage tank, absorbs heat through the molten salt storage heat exchanger, and then enters above the thermocline heat storage tank. The remaining portion enters the main heat exchanger to provide heat to the multi-stage heaters. (2) In the case of insufficient solar radiation, the high-temperature molten salt at the top of the thermocline heat storage tank is released into the molten salt storage heat exchanger and then enters the low-temperature molten salt side at the bottom of the thermocline. The molten salt medium in the molten salt storage heat exchanger absorbs heat in the molten salt storage heat exchanger and then releases heat in the main heat exchanger to supply the heat exchange required by the first-stage heater, the second-stage heater and the third-stage heater; (3) After the boiler inlet feedwater absorbs heat in the first-stage heat exchanger to form high-temperature and high-pressure steam, it flows into the unit's main steam system; at the same time, the condensate at the feedwater pump outlet is pressurized and absorbs heat in the first-stage heater to form high-temperature steam, which flows into the unit's reheat steam system. The above steam production process forms a complementary steam system of solar thermal and coal-fired boiler.

[0041] (4) Molten salt industrial steam supply system: The condensate from the deaerator is pressurized by a water pump and then absorbs heat in the third-stage heat exchanger to form 3MPa-level industrial steam for external heating.

[0042] (5) Cold Recycled Industrial Steam Supply System: A portion of the steam is drawn from the cold recycled steam header of the unit for industrial steam supply at a pressure of 1.5 MPa.

[0043] (6) Main steam supply system: High-pressure industrial steam supply is provided by drawing main steam from the molten salt system and coal-fired boiler outlet. This site can provide industrial steam at a pressure of 3~24MPa.

[0044] (7) Hot resteam supply system: Industrial steam supply is provided by extracting hot resteam from the molten salt system and coal-fired boiler outlet. This site can provide industrial steam at a level of 1.5 MPa.

[0045] This embodiment can form a complementary multi-stage steam supply system based on solar thermal energy storage and boiler, which can provide steam under various conditions, including when solar energy is abundant or insufficient. Based on this system, different grades of industrial steam can be provided to industrial systems, effectively reducing costs. While meeting the deep peak shaving requirements of the power grid, it can both ensure the industrial steam supply needs and reduce the coal consumption of the generating unit.

[0046] 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℃, extraction steam rate 100t / h, and main steam flow rate set at 1008.51t / h, the coal consumption for power generation of the proposed scheme is only 235.02 g / 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 proposed scheme is reduced by 41.55 g / kWh, demonstrating a significant coal-saving effect.

[0047] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A boiler-complementary multi-stage steam supply system coupled with thermotropic solar thermal energy storage, characterized in that, The system includes: a solar energy storage system, a thermal power heating system, and a steam supply system; wherein... The solar energy storage system includes a solar tower, a molten salt storage heat exchanger, a thermocline storage tank, a main heat exchanger, and a multi-stage heater. The solar tower is connected to the molten salt storage heat exchanger and the main heat exchanger, respectively. The molten salt storage heat exchanger is connected to the inclined temperature layer heat storage tank and the main heat exchanger, respectively. The main heat exchanger is connected to the multi-stage heater. The thermal power heating system includes a boiler, a regenerative system, and a steam turbine. The feedwater inlets of the boiler and the regenerative system are connected to the inlets of the multi-stage heaters. The steam outlets of the multi-stage heaters and the boiler are connected to the steam inlets of the steam turbines. The multi-stage heater is connected to the steam outlet of the boiler via the steam supply system.

2. The system according to claim 1, characterized in that, The inclined thermosphere thermal storage tank includes a high-temperature molten salt storage section located in the upper region and a low-temperature molten salt storage section located in the lower region; The high-temperature molten salt storage section and the low-temperature molten salt storage section are both connected to the molten salt storage heat exchanger. The high-temperature molten salt storage section stores high-temperature molten salt, and the low-temperature molten salt storage section stores low-temperature molten salt. When solar radiation is insufficient, the high-temperature molten salt in the high-temperature molten salt storage section enters the molten salt storage heat exchanger to release heat. The molten salt medium in the main heat exchanger absorbs heat in the molten salt storage heat exchanger and releases heat in the main heat exchanger to provide heat to the multi-stage heater.

3. The system according to claim 1, characterized in that, The multi-stage heater includes a first-stage heater, and the steam turbine includes a high-pressure cylinder, wherein... The molten salt outlet of the main heat exchanger is connected to the molten salt inlet of the first-stage heater; The inlet of the first-stage heater is connected to the regenerative system and the feedwater of the boiler. The main steam outlet of the first-stage heater and the main steam outlet of the boiler are connected to the main steam inlet of the high-pressure cylinder through the main steam pipeline.

4. The system according to claim 3, characterized in that, The steam supply system includes a main steam supply pipeline connected to the main steam pipeline, used to provide industrial steam at a pressure of 3-24 MPa.

5. The system according to claim 3, characterized in that, The cold resteam outlet of the high-pressure cylinder is connected to the cold resteam inlet of the boiler via a cold resteam pipeline; wherein, The steam supply system includes a cold reheat industrial steam supply pipeline connected to a cold reheat steam pipeline for providing industrial steam at a pressure of 1.5 MPa.

6. The system according to claim 3, characterized in that, The multi-stage heater further includes a second-stage heater, and the steam turbine includes an intermediate-pressure cylinder; wherein... The molten salt inlet of the second-stage heater is connected to the molten salt outlet of the main heat exchanger. The hot resteam outlet of the second-stage heater is connected to the hot resteam outlet of the boiler and the hot resteam inlet of the intermediate-pressure cylinder through a hot resteam pipeline. The second-stage heater is also connected to the feedwater inlet of the regenerative system and the feedwater inlet of the boiler.

7. The system according to claim 6, characterized in that, The steam supply system includes a hot resteam supply pipeline connected to the hot resteam pipeline, used to provide industrial steam at a pressure of 1.5 MPa.

8. The system according to claim 6, characterized in that, The multi-stage heater also includes a third-stage heater. The molten salt inlet of the third-stage heater is connected to the molten salt outlet of the first-stage heater and the molten salt outlet of the second-stage heater, respectively. The molten salt outlet of the third-stage heater is connected to the molten salt inlet of the main heat exchanger. The third-stage heater is also connected to the water supply port of the regenerative system.

9. The system according to claim 8, characterized in that, The steam supply system includes a molten salt industrial steam supply line connected to the steam supply line of the third-stage heater, for providing industrial steam at a pressure of 1.5 MPa.

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