Deep peak regulation and frequency modulation system for coal-fired unit

Abstract

The invention belongs to the field of coal-fired unit fused salt heat storage, peak regulation and frequency modulation, and particularly discloses a coal-fired unit deep peak regulation and frequency modulation system which comprises a power generation unit and a fused salt heat exchange unit, and the fused salt heat exchange unit comprises a low-temperature fused salt storage tank, a high-temperature fused salt storage tank, a heat storage assembly and a heat release assembly. One path of main steam introduced into the boiler of the heat storage assembly exchanges heat with low-temperature fused salt and part of boiler feed water in sequence and then is sent to an outlet of a feed pump, part of boiler feed water after heat absorption is sent to an outlet of a high-pressure cylinder, and the other path of reheated steam introduced into the boiler exchanges heat with low-temperature fused salt and then is sent to a middle stage of an intermediate-pressure cylinder. One path of the heat release assembly introduces outlet steam of the high-pressure cylinder, exchanges heat with high-temperature fused salt and then is fed into an inlet of the medium-pressure cylinder, and the other path of the heat release assembly introduces feed water of an economizer in the boiler, exchanges heat with smoke and the high-temperature fused salt in sequence and then is fed into an inlet of the high-pressure cylinder. Energy loss caused by the throttling valve can be avoided, heat is further recycled, the energy loss is reduced to the maximum degree, and rapid load rising can be achieved.

Description

Technical Field

[0001] The present application belongs to the field of molten salt heat storage peak-shaving and frequency regulation of coal-fired units, and more specifically, relates to a deep peak-shaving and frequency regulation system for coal-fired units. Background Art

[0002] The peak and frequency regulation of coal-fired units is mainly to adjust the output of coal-fired units according to the changes in the load of the power grid to meet the power demand of the power system at different times, and to maintain the stability of the power system frequency by adjusting the output of coal-fired units. At present, the large-scale intervention of renewable energy with strong volatility has put forward higher requirements for the peak and frequency regulation of coal-fired units.

[0003] The main technical solution currently used is to store heat in molten salt at low load to reduce the amount of steam entering the turbine and achieve the purpose of deep peak regulation; the stored heat is released during peak hours to achieve a cycle of stored heat. In this cycle, how to achieve efficient heat storage and heat release cycles for the unit is the key to the economical and efficient operation of molten salt heat storage.

[0004] Most of the existing technologies are to extract the main steam to release heat to the molten salt, and the steam after heat release enters the high-pressure cylinder outlet or is introduced into the boiler feed water side. The scheme of introducing the steam after heat release into the boiler feed water side can make full use of the latent heat of vaporization and has good economy, but it is necessary to reduce the steam temperature to near the feed water temperature, so it is necessary to use low melting point salts such as HITEC salts; but in engineering applications, the maximum operating temperature of HITEC salts cannot exceed 400℃, so the main steam of about 550℃ will release heat to the molten salt, which will cause more exergy loss, and the molten salt of about 400℃ can only heat the steam to below 400℃ during the heat release process. For the scheme of sending the steam after heat release to the high-pressure cylinder outlet, it is necessary to throttle and reduce the pressure, which will seriously increase the exergy loss.

[0005] At the same time, the current boiler load increase rate is generally less than 3%Pe / min. If the requirement of more than 5%Pe / min is to be achieved, molten salt can be used to achieve an additional 2-3%Pe / min. In the existing technology, in the heat release and rapid load increase of molten salt, the steam at the outlet of the high-pressure cylinder is heated by high-temperature molten salt and then introduced into the inlet of the medium-pressure cylinder to increase the load increase rate, but it is difficult to achieve a load increase rate of 2%Pe / min by relying solely on the medium-pressure cylinder; at the same time, the boiler feed water is directly heated to the main steam or reheat steam parameters using high-temperature molten salt. The latent heat of vaporization of water requires a large amount of heat, which will produce a large exergy loss on the one hand, and will also consume more heat to heat the feed water to the required parameters, which requires more molten salt and larger storage tanks, which is more expensive. Summary of the invention

[0006] In view of the defects of the prior art, the present application provides a deep peak-shaving and frequency-regulating system for coal-fired units, aiming to solve the problem of excessive exergy loss during steam heat release in the peak-shaving system in the prior art.

[0007] The present application provides a deep peak-shaving and frequency-regulating system for a coal-fired unit, which specifically includes a power generation unit and a molten salt heat exchange unit, wherein: The power generation unit includes a boiler, a feed water pump, a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder; The molten salt heat exchange unit comprises a low-temperature molten salt storage tank, a high-temperature molten salt storage tank, and a heat storage component and a heat release component respectively connected to the low-temperature molten salt storage tank and the high-temperature molten salt storage tank. One path of the heat storage component introduces the main steam of the boiler, which is successively heat-exchanged with the low-temperature molten salt and part of the boiler feed water and then sent to the outlet of the feed water pump. At the same time, the boiler feed water after absorbing heat is sent to the outlet of the high-pressure cylinder. Another path of the heat storage component introduces the reheated steam of the boiler and is heat-exchanged with the low-temperature molten salt and then sent to the middle stage of the medium-pressure cylinder; one path of the heat release component introduces the outlet steam of the high-pressure cylinder and is heat-exchanged with the high-temperature molten salt before being sent to the inlet of the medium-pressure cylinder. Another path of the heat release component introduces the feed water preheated by the economizer in the boiler, which is successively heat-exchanged with the flue gas and the high-temperature molten salt and then sent to the inlet of the high-pressure cylinder.

[0008] Through the above technical scheme conceived by the present application, compared with the prior art, since the present application sends the main steam after heat release to the outlet of the feed water pump after heat exchange with the boiler feed water during heat storage, the energy loss caused by the throttle valve can be avoided and the heat can be further recovered, thereby minimizing the energy loss, and the phenomenon of overheating of the reheater caused by extracting the main steam can also be avoided; The present application can simultaneously increase the steam flow of the high-pressure cylinder and the medium-pressure cylinder during heat release, thereby achieving rapid load increase and reducing the force imbalance problem of the two cylinders. At the same time, the boiler preheating feed water is first preheated by the flue gas and then heat exchanged with the high-temperature molten salt, which can reduce exergy loss and improve efficiency.

[0009] As a further preference, the molten salt heat exchange unit uses solar salt as the heat storage medium.

[0010] As further preferred, the operating temperature of the molten salt heat exchange unit is 300°C to 560°C.

[0011] As a further preferred embodiment, the heat storage component includes a main steam-molten salt heat exchanger, a reheat steam-molten salt heat exchanger and a feed water-main steam heat exchanger, the molten salt inlet of the main steam-molten salt heat exchanger is connected to a low-temperature molten salt storage tank, the molten salt outlet is connected to a high-temperature molten salt storage tank, the medium inlet is connected to the main steam pipeline of the boiler, and the medium outlet is connected to the outlet of the feed water pump through the feed water-main steam heat exchanger; the molten salt inlet of the reheat steam-molten salt heat exchanger is connected to a low-temperature molten salt storage tank, the molten salt outlet is connected to a high-temperature molten salt storage tank, the medium inlet is connected to the high-temperature reheat outlet of the boiler, and the medium outlet is connected to the intermediate stage of the medium pressure cylinder; the feed water inlet of the feed water-main steam heat exchanger is connected to the outlet of the feed water pump, the feed water outlet is connected to the outlet of the high-pressure cylinder, the medium inlet is connected to the medium outlet of the main steam-molten salt heat exchanger, and the medium outlet is connected to the inlet of the feed water pump.

[0012] As further preferred, the heat storage component also includes a molten salt electric heater, which is arranged between the high-temperature molten salt storage tank and the reheat steam-molten salt heat exchanger and the main steam-molten salt heat exchanger for electrically heating the molten salt.

[0013] As further preferred, the heat storage assembly also includes a booster pump, which is arranged between the outlet of the feed water-main steam heat exchanger and the outlet of the feed water pump, and is used to increase the pressure of the main steam after heat release.

[0014] As a further preference, the outlet pressure of the booster pump is not lower than the outlet pressure of the water feed pump.

[0015] As a further preferred embodiment, the heat release component includes a molten salt-main steam heat exchanger, a molten salt-reheat steam heat exchanger and a flue gas-feed water heat exchanger, the molten salt inlet of the molten salt-main steam heat exchanger is connected to a high-temperature molten salt storage tank, the molten salt outlet is connected to a low-temperature molten salt storage tank, and the medium inlet is connected to the outlet of the economizer through the flue gas-feed water heat exchanger; the molten salt inlet of the molten salt-reheat steam heat exchanger is connected to a high-temperature molten salt storage tank, the molten salt outlet is connected to a low-temperature molten salt storage tank, the medium inlet is connected to the outlet of the high-pressure cylinder, and the medium outlet is connected to the inlet of the medium-pressure cylinder; the flue gas inlet of the flue gas-feed water heat exchanger is connected to the furnace outlet, and the smoke gas outlet is connected to the smoke gas inlet of the economizer.

[0016] In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art: 1. In the present application, the main steam after heat release is exchanged with boiler feed water and then sent to the outlet of the feed water pump during heat storage, following the pressure matching principle, which can avoid energy loss caused by the throttle valve and minimize energy loss; at the same time, the boiler feed water of part of the feed water pump is drawn out for heat exchange with the main steam after heat storage, which can reduce the temperature of this part of the steam to the outlet temperature of the feed water pump, avoiding the power circulation problem caused by the increase of feed water temperature; the feed water after heat absorption is sent to the outlet of the high-pressure cylinder, which can avoid the phenomenon of overheating of the reheater temperature caused by extracting the main steam, and can also avoid the problem of too low main steam extraction; when releasing heat, the steam flow of the high-pressure cylinder and the low-pressure cylinder can be increased at the same time, so as to achieve rapid load increase and reduce the problem of unbalanced force on the two cylinders. At the same time, the boiler preheating feed water is first preheated by flue gas and then heat exchanged with high-temperature molten salt, which can reduce exergy loss and improve efficiency; 2. At the same time, the application uses solar salt and sets the operating temperature to 300℃~560℃, which can reduce the exergy loss in the main steam heat release process and make the steam reach higher parameters in the molten salt heat release process; 3. In addition, the present application provides a molten salt electric heater, which can use electric heating to make the molten salt temperature reach above 560°C, so that it reaches the highest operating temperature, which is conducive to subsequent rapid load increase. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a heat storage flow chart of a deep peak-shaving and frequency-regulating system for a coal-fired unit provided in an embodiment of the present application; Figure 2 It is a heat release flow chart of the deep peak-shaving and frequency-regulating system of a coal-fired unit provided in an embodiment of the present application.

[0018] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1: Low-temperature molten salt storage tank, 2: High-temperature molten salt storage tank, 3: Reheat steam-molten salt heat exchanger, 4: Main steam-molten salt heat exchanger, 5: Molten salt electric heater, 6: Feed water-main steam heat exchanger, 7: Molten salt-main steam heat exchanger, 8: Molten salt-reheat steam heat exchanger, 9: Feed water pump, 10: Boiler, 11: High-pressure cylinder, 12: Medium-pressure cylinder, 13: Low-pressure cylinder, 14: Low-temperature superheater, 15: Low-temperature reheater, 16: Economizer, 17: Flue gas-feed water heat exchanger, 18: Steam drum, 19: Furnace, 20: Booster pump, 21: High-temperature reheater. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0020] like Figure 1 ,2 As shown, the present application provides a deep peak-shaving and frequency-regulating system for a coal-fired unit, which specifically includes a power generation unit and a molten salt heat exchange unit, wherein: The power generation unit includes a boiler 10, a feed water pump 9, a high-pressure cylinder 11, an intermediate-pressure cylinder 12 and a low-pressure cylinder 13. The boiler 10 includes a furnace 19, a steam drum 18, a low-temperature superheater 14, a low-temperature reheater 15, a high-temperature reheater 21 and an economizer 16. The furnace 19 is the place where the fuel burns. It is lined with a special high-temperature resistant material and can withstand a high temperature environment of up to 1500°C to ensure that the fuel is fully burned here and release a large amount of heat energy. The steam drum 18 is an important component for steam-water separation and steam storage. It is equipped with an efficient steam-water separation device inside, which can effectively separate the steam-water mixture from the water-cooled wall riser to ensure the quality of the output steam. The steam drum has a large volume and can stably Steam pressure can meet the demand for steam under different working conditions; the low-temperature superheater 14 is responsible for further heating the saturated steam separated from the drum to make it reach a superheated state and improve the working capacity of the steam. The superheater is made of advanced alloy steel pipes and has good high-temperature resistance and corrosion resistance. It can operate stably under the harsh environment of high temperature and high pressure; the low-temperature reheater 15 and the high-temperature reheater 21 are used to reheat the steam discharged from the high-pressure cylinder 11 in turn to increase the enthalpy value of the steam, thereby improving the cycle thermal efficiency of the entire unit; the economizer 16 is installed in the tail flue of the boiler 10, and uses the waste heat of the flue gas at the tail of the boiler 10 to heat the feed water, reduce the exhaust gas temperature, and improve the thermal efficiency of the boiler; The high-pressure cylinder 11, the intermediate-pressure cylinder 12 and the low-pressure cylinder 13 constitute a steam turbine. Steam first enters the high-pressure cylinder 11. Under the action of a series of nozzles and moving blades, the pressure and temperature of the steam in the high-pressure cylinder 11 gradually decrease, and the thermal energy of the steam is converted into mechanical energy to drive the rotor to rotate; the steam discharged from the high-pressure cylinder 11 enters the intermediate-pressure cylinder 12 to continue to expand and do work, and the steam discharged from the intermediate-pressure cylinder 12 enters the low-pressure cylinder 13 to continue to expand and do work, and the pressure and temperature are further reduced until it is discharged to the condenser; The molten salt heat exchange unit includes a low-temperature molten salt storage tank 1, a high-temperature molten salt storage tank 2, and a heat storage component and a heat release component connected to the low-temperature molten salt storage tank 1 and the high-temperature molten salt storage tank 2 respectively. One path of the heat storage component introduces the main steam of the boiler 10 and exchanges heat with the low-temperature molten salt and part of the boiler feed water (the feed water sent by the feed water pump 9 is the boiler feed water) in succession, and then is sent to the outlet of the feed water pump 9. At the same time, the boiler feed water after absorbing heat is sent to the outlet of the high-pressure cylinder 11. Considering that the temperature of the main steam after heat release (the main steam after heat exchange with the low-temperature molten salt) is 3 00℃ or above, so part of the boiler feed water is drawn out from the feed water pump 9 and exchanged with the main steam after heat release before being sent to the outlet of the high-pressure cylinder 11, so as to use the heat of the main steam after heat release to heat part of the feed water at the middle tap of the feed water pump 9, and condense the main steam after heat release into water and send it to the outlet of the feed water pump 9, so as to avoid the safety problem of boiler steam-water circulation caused by excessively high temperature of the main steam after heat release. Another way of the heat storage component introduces the reheated steam of the boiler 10 and exchanges heat with the low-temperature molten salt before being sent to the middle stage of the medium-pressure cylinder 12; One path of the heat release component introduces the outlet steam of the high-pressure cylinder 11 and exchanges heat with the high-temperature molten salt before being sent to the inlet of the medium-pressure cylinder 12. Another path of the heat release component introduces the preheated feed water of the economizer 16 in the boiler 10, and exchanges heat with the flue gas and the high-temperature molten salt in succession before being sent to the inlet of the high-pressure cylinder 11. Since the amount of steam from the outlet of the high-pressure cylinder 11 entering the boiler 10 becomes less, a flue gas bypass is set in the tail flue of the boiler 10 to further preheat the feed water preheated by the economizer 16, and then the preheated steam is exchanged with the high-temperature molten salt and merged into the main steam pipeline to enter the high-pressure cylinder 11.

[0021] During heat storage, the present application exchanges heat between the main steam and low-temperature molten salt and boiler feed water and sends it to the outlet of the feed water pump, and sends the heated boiler feed water to the outlet of the high-pressure cylinder. Compared with the solution of directly sending the main steam after heat release to the outlet of the high-pressure cylinder, the energy loss caused by pressure reduction and throttling is avoided; at the same time, compared with the solution of introducing the main steam after heat release into the boiler feed water side, the heat can be further recovered by heat exchange with the boiler feed water, thereby minimizing the energy loss; introducing part of the boiler feed water into the outlet of the high-pressure cylinder can avoid the overheating of the reheater, and the main steam can be extracted at a large flow rate for heat storage, thereby realizing deep peak regulation.

[0022] Taking into account that the heating and evaporation heat absorption share of boiler feed water is more than 50%, while the superheating share is only less than 35%, it is more economical to use high-temperature molten salt for the superheating share and flue gas for the heating and evaporation share. Therefore, the present application sends the steam after heat exchange into the medium-pressure cylinder and the high-pressure cylinder respectively during heat release, which can quickly increase the steam flow of the high-pressure cylinder and the medium-pressure cylinder at the same time, thereby achieving rapid load increase and reducing the force imbalance problem of the two cylinders. Compared with the prior art solution that only relies on the medium-pressure cylinder to increase the load, it can effectively improve the load increase rate; at the same time, the feed water preheated by the economizer is first preheated by the flue gas and then heat exchanged with the high-temperature molten salt, which can reduce exergy loss, improve efficiency, and be more economical.

[0023] Furthermore, considering that the maximum operating temperature of HITEC salt should not exceed 400°C, when the temperature of the molten salt is lower than 400°C, there will be more exergy loss in the main steam heat release process, and the steam cannot reach higher parameters during the heat release process of the high-temperature molten salt at 400°C. Therefore, the molten salt heat exchange unit of the present application uses solar salt as the heat storage medium, and the operating temperature of the molten salt heat exchange unit is 300°C~560°C to prevent decomposition during long-term use, thereby effectively reducing the exergy loss in the main steam heat release process and enabling the steam to reach higher parameters during the heat release process.

[0024] Further, the heat storage component includes a main steam-molten salt heat exchanger 4, a reheat steam-molten salt heat exchanger 3 and a feed water-main steam heat exchanger 6. The molten salt inlet of the main steam-molten salt heat exchanger 4 is connected to the low-temperature molten salt storage tank 1, the molten salt outlet is connected to the high-temperature molten salt storage tank 2, the medium inlet is connected to the main steam pipeline of the boiler 10, and the medium outlet is connected to the outlet of the feed water pump 9 through the feed water-main steam heat exchanger 6; the molten salt inlet of the reheat steam-molten salt heat exchanger 3 is connected to the low-temperature molten salt storage tank 1, the molten salt outlet is connected to the high-temperature molten salt storage tank 2, the medium inlet is connected to the outlet of the high-temperature reheater 21, and the medium outlet is connected to the intermediate stage of the medium pressure cylinder 12; the feed water inlet of the feed water-main steam heat exchanger 6 is connected to the outlet of the feed water pump 9, the feed water outlet after absorbing heat is connected to the outlet of the high-pressure cylinder 11, the medium inlet is connected to the medium outlet of the main steam-molten salt heat exchanger 4, and the medium outlet is connected to the inlet of the feed water pump 9.

[0025] More preferably, the heat storage component also includes a molten salt electric heater 5, which is arranged between the high-temperature molten salt storage tank 2 and the reheat steam-molten salt heat exchanger 3 and the main steam-molten salt heat exchanger 4, and is used to electrically heat the molten salt to above the main steam temperature.

[0026] More preferably, considering that the main steam after heat release has a slightly lower pressure than the main steam of the boiler 10 (heat exchanger pressure drop), and the outlet pressure of the feedwater pump 9 is usually slightly higher than the main steam pressure by 4Mpa to 6Mpa, the heat storage component also includes a booster pump 20, which is arranged between the outlet of the feedwater-main steam heat exchanger 6 and the outlet of the feedwater pump 9, and is used to boost the main steam after heat release to avoid causing a decrease in the outlet pressure of the feedwater pump 9. The outlet pressure of the booster pump 20 is not lower than the outlet water pressure of the feedwater pump 9.

[0027] Furthermore, the heat release component includes a molten salt-main steam heat exchanger 7, a molten salt-reheat steam heat exchanger 8 and a flue gas-feed water heat exchanger 17. The molten salt inlet of the molten salt-main steam heat exchanger 7 is connected to the high-temperature molten salt storage tank 2, the molten salt outlet is connected to the low-temperature molten salt storage tank 1, and the medium inlet is connected to the outlet of the economizer 16 through the flue gas-feed water heat exchanger 17; the molten salt inlet of the molten salt-reheat steam heat exchanger 8 is connected to the high-temperature molten salt storage tank 2, the molten salt outlet is connected to the low-temperature molten salt storage tank 1, the medium inlet is connected to the outlet of the high-pressure cylinder 11, and the medium outlet is connected to the inlet of the medium-pressure cylinder 12; the flue gas inlet of the flue gas-feed water heat exchanger 17 is connected to the outlet of the furnace 19, and the flue gas outlet is connected to the flue gas inlet of the economizer 16, and the high-temperature flue gas first passes through the flue gas-feed water heat exchanger 17 and then enters the economizer 16.

[0028] The heat storage process of the deep peak-shaving and frequency-regulating system of the coal-fired unit provided in the present application is as follows: the low-temperature molten salt is pumped from the low-temperature molten salt storage tank 1 through the main steam-molten salt heat exchanger 4 and the reheated steam-molten salt heat exchanger 3 to absorb heat and then enter the high-temperature molten salt storage tank 2. Among them, part of the main steam is extracted to enter the main steam-molten salt heat exchanger 4, and part of the reheated steam is extracted to enter the reheated steam-molten salt heat exchanger 3; the main steam after heat release passes through the feed water-main steam heat exchanger 6 and is pressurized by the booster pump 20 and sent to the outlet of the feed water pump 9; the reheated steam after heat release through the reheated steam-molten salt heat exchanger 4 is introduced into the middle stage of the medium pressure cylinder; the electric energy generated by the main steam turbine generator is partially introduced into the molten salt electric heater 5, which can electrically heat part of the molten salt and further heat the molten salt to more than 560 degrees.

[0029] The heat release process of the deep peak-shaving and frequency-regulating system of the coal-fired unit provided in the present application is as follows: the high-temperature molten salt is pumped from the high-temperature molten salt storage tank 2 through the molten salt-main steam heat exchanger 7 and the molten salt-reheat steam heat exchanger 8 and then enters the low-temperature molten salt storage tank 1. Among them, part of the steam at the outlet of the high-pressure cylinder 11 is heated by the molten salt-reheat steam heat exchanger 7 and then merged into the reheat steam pipeline; the feed water at the outlet of the economizer 16 is further preheated by the flue gas-feed water heat exchanger 17 in the flue bypass and then enters the molten salt-main steam heat exchanger 7 for heating and then merges into the main steam pipeline.

[0030] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A deep peak-shaving and frequency-modulating system for coal-fired units, characterized in that: It includes a power generation unit and a molten salt heat exchange unit, wherein: The power generation unit comprises a boiler (10), a water supply pump (9), a high-pressure cylinder (11), a medium-pressure cylinder (12) and a low-pressure cylinder (13); The molten salt heat exchange unit comprises a low-temperature molten salt storage tank (1), a high-temperature molten salt storage tank (2), and a heat storage component and a heat release component respectively connected to the low-temperature molten salt storage tank (1) and the high-temperature molten salt storage tank (2). One path of the heat storage component introduces the main steam of the boiler (10) and exchanges heat with the low-temperature molten salt and part of the boiler feed water in sequence, and then sends it to the outlet of the feed water pump (9). At the same time, the boiler feed water after absorbing heat is sent to the outlet of the high-pressure cylinder (11). Another path of the heat storage component introduces the reheated steam of the boiler (10) and exchanges heat with the low-temperature molten salt and then sends it to the middle stage of the medium-pressure cylinder (12). One path of the heat release component introduces the outlet steam of the high-pressure cylinder (11) and exchanges heat with the high-temperature molten salt and then sends it to the inlet of the medium-pressure cylinder (12). Another path of the heat release component introduces the feed water preheated by the economizer (16) in the boiler (10), and exchanges heat with the flue gas and the high-temperature molten salt in sequence, and then sends it to the inlet of the high-pressure cylinder (11).

2. The deep peak-shaving and frequency-modulating system for coal-fired units according to claim 1, characterized in that: The molten salt heat exchange unit uses solar salt as the heat storage medium.

3. The deep peak-shaving and frequency-modulating system for coal-fired units according to claim 2, characterized in that: The operating temperature of the molten salt heat exchange unit is 300°C to 560°C.

4. The deep peak-shaving and frequency-modulating system for coal-fired units according to claim 1, characterized in that: The heat storage component comprises a main steam-molten salt heat exchanger (4), a reheat steam-molten salt heat exchanger (3) and a feed water-main steam heat exchanger (6); the molten salt inlet of the main steam-molten salt heat exchanger (4) is connected to a low-temperature molten salt storage tank (1), the molten salt outlet is connected to a high-temperature molten salt storage tank (2), the medium inlet is connected to a main steam pipeline of a boiler (10), and the medium outlet is connected to an outlet of a feed water pump (9) through the feed water-main steam heat exchanger (6); the molten salt of the reheat steam-molten salt heat exchanger (3) is connected to a low-temperature molten salt storage tank (1), the medium outlet is connected to a high-temperature molten salt storage tank (2), the medium inlet is connected to a main steam pipeline of a boiler (10), and the medium outlet is connected to an outlet of a feed water pump (9) through the feed water-main steam heat exchanger (6); The inlet is connected to the low-temperature molten salt storage tank (1), the molten salt outlet is connected to the high-temperature molten salt storage tank (2), the medium inlet is connected to the outlet of the high-temperature reheater (21) of the boiler, and the medium outlet is connected to the middle stage of the medium-pressure cylinder (12); the feed water inlet of the feed water-main steam heat exchanger (6) is connected to the outlet of the feed water pump (9), the feed water outlet is connected to the outlet of the high-pressure cylinder (11), the medium inlet is connected to the medium outlet of the main steam-molten salt heat exchanger (4), and the medium outlet is connected to the inlet of the feed water pump (9).

5. The deep peak-shaving and frequency-modulating system for coal-fired units according to claim 4, characterized in that: The heat storage component further comprises a molten salt electric heater (5), which is arranged between the high-temperature molten salt storage tank (2) and the reheat steam-molten salt heat exchanger (3) and the main steam-molten salt heat exchanger (4) and is used for electrically heating the molten salt.

6. The deep peak-shaving and frequency-modulating system for coal-fired units according to claim 4, characterized in that: The heat storage assembly further comprises a booster pump (20), which is arranged between the outlet of the feed water-main steam heat exchanger (6) and the outlet of the feed water pump (9) and is used to increase the pressure of the main steam after heat release.

7. The deep peak-shaving and frequency-modulating system for coal-fired units according to claim 6, characterized in that: The outlet pressure of the booster pump (20) is not lower than the outlet pressure of the water supply pump (9).

8. The deep peak-shaving and frequency-modulating system for coal-fired units according to any one of claims 1 to 7, characterized in that: The heat release component comprises a molten salt-main steam heat exchanger (7), a molten salt-reheat steam heat exchanger (8) and a flue gas-feed water heat exchanger (17); the molten salt inlet of the molten salt-main steam heat exchanger (7) is connected to a high-temperature molten salt storage tank (2), the molten salt outlet is connected to a low-temperature molten salt storage tank (1), and the medium inlet is connected to the outlet of an economizer (16) through the flue gas-feed water heat exchanger (17); the molten salt inlet of the molten salt-reheat steam heat exchanger (8) is connected to a high-temperature molten salt storage tank (2), the molten salt outlet is connected to a low-temperature molten salt storage tank (1), the medium inlet is connected to the outlet of a high-pressure cylinder (11), and the medium outlet is connected to the inlet of a medium-pressure cylinder (12); the flue gas inlet of the flue gas-feed water heat exchanger (17) is connected to the outlet of a furnace (19), and the flue gas outlet is connected to the flue gas inlet of an economizer (16).

Images