Fused salt energy storage coupling thermal power generating unit flexible peak regulation system

Abstract

The utility model provides a flexible peak shaving system for a fused salt energy storage coupling thermal power generating unit. The flexible peak shaving system comprises a thermal power generation system, a fused salt heat absorption unit, a fused salt storage unit and a fused salt heat release unit. In the peak regulation stage of the thermal power generating unit, the fused salt heat absorption unit operates, part of main steam is extracted to serve as a heat source and exchanges heat with fused salt to achieve fused salt heat absorption, meanwhile, the fused salt heat release unit operates, a first steam return pipe is opened and used for supplementing boiler reheat steam, the problem of boiler cold overtemperature during fused salt energy storage is solved, and the system can operate smoothly and safely. When the thermal power generating unit operates at the peak, the fused salt heat release unit operates, the fused salt heat absorption unit does not operate, the first steam return pipe is closed, high-temperature fused salt heats supplied water shunted by the water supply unit to generate steam, and the steam converges to a main steam pipeline and / or a reheat steam pipeline through a pipeline and / or exchanges heat with condensate water of the water supply unit through the pipeline. And the molten salt heat release process is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of flexibility transformation of thermal power units, and particularly relates to a molten salt energy storage coupled thermal power unit flexibility peak shaving system. Background Technique

[0002] Due to the continuous increase in the installed capacity ratio of new energy, the power grid has an increasing demand for the flexibility peak shaving of thermal power. At present, when some provinces conduct deep peak shaving, thermal power plants can obtain peak shaving benefits. In order to respond to the national goals of carbon neutrality and carbon peak, and improve the peak shaving ability of thermal power plants, the current minimum deep peak shaving ability of traditional thermal power plants is 30% to 20%. Currently, conventional thermal power peak shaving transformation technologies include stable combustion adjustment technology under low load, oxy-fuel combustion technology, wide-load denitrification technology, etc. There are also proposed solutions that combine molten salt energy storage with thermal power flexibility peak shaving. By extracting main steam to heat molten salt energy storage, the purpose of reducing the electric load of the steam turbine is achieved. However, when the extraction steam volume is large, the flow rates of the boiler superheater and reheater are mismatched, and there is a problem of overheating of the boiler reheater, which seriously threatens the safe operation of the boiler.

[0003] Currently, the conventional solution to the problem of overheating of the boiler reheater is to use a steam ejector to send a part of the cooled main steam into the reheated steam inlet pipe. However, due to the large variation in the load parameters of the boiler, it is difficult to adjust the steam when the steam ejector fluctuates with the peak shaving load of the boiler, and there are significant safety risks to the operation. Content of the Utility Model

[0004] In view of the above technical problems, the utility model provides a molten salt energy storage coupled thermal power unit flexibility peak shaving system. During the peak shaving operation of the thermal power unit, a part of the boiler main steam is extracted to heat the molten salt energy storage through the molten salt heat absorption unit. At the same time, the molten salt heat release unit generates steam with the same parameters and incorporates it into the reheated steam inlet pipe, solving the problem of overheating of the boiler reheater during molten salt energy storage and enabling the system to operate smoothly and safely.

[0005] To achieve the above object, the technical solution of the utility model is as follows:

[0006] A molten salt energy storage coupled thermal power unit flexibility peak shaving system includes a thermal power generation system and a molten salt energy storage system. The thermal power generation system includes a boiler, a feed water unit, a steam turbine, and a generator. The steam turbine includes a high-pressure cylinder, a medium-pressure cylinder, and a low-pressure cylinder. The main steam outlet of the boiler is connected to the main steam pipeline, and the reheated steam outlet of the boiler is connected to the reheated steam pipeline. The molten salt energy storage system includes a molten salt heat absorption unit, a molten salt heat release unit, and a molten salt storage unit. The molten salt storage unit includes a cold salt tank and a hot salt tank. The molten salt heat absorption unit includes a main steam molten salt superheater, a main steam molten salt condenser, and a main steam molten salt subcooler. The main steam outlet of the boiler is also connected to the main steam extraction pipeline.

[0007] The main steam pipeline is connected to the steam inlet of the high-pressure cylinder. The steam outlet of the high-pressure cylinder is connected to the reheat steam inlet pipe, and the reheat steam inlet pipe is connected to the reheat steam inlet of the boiler. The main steam extraction pipeline is successively connected to the main steam molten salt superheater, the main steam molten salt condenser, and the main steam molten salt subcooler. The condensate outlet of the main steam molten salt subcooler is connected to the boiler through the boiler feed water inlet pipe.

[0008] The molten salt outlet of the cold salt tank is successively connected to the main steam molten salt subcooler, the main steam molten salt condenser, the main steam molten salt superheater, and the hot salt tank.

[0009] The molten salt outlet of the hot salt tank is connected to the molten salt inlet of the molten salt heat release unit. The molten salt outlet of the molten salt heat release unit is connected to the molten salt inlet of the cold salt tank. The feed water unit is connected to the condensate inlet of the molten salt heat release unit through a feed water branch. The pipeline connected to the steam outlet of the molten salt heat release unit includes a first steam return pipe and a second steam return pipe. The first steam return pipe is connected to the reheat steam inlet pipe. The second steam return pipe is connected to the main steam pipeline and / or the reheat steam pipeline.

[0010] A reheat steam compensation parallel valve is provided on the first steam return pipe.

[0011] In a preferred embodiment of the present utility model, the molten salt heat absorption unit further includes a reheat steam molten salt heater. The molten salt outlet of the cold salt tank is respectively connected to the molten salt inlets of the reheat steam molten salt heater and the main steam molten salt subcooler. The molten salt outlets of the reheat steam molten salt heater and the main steam molten salt superheater are both connected to the molten salt inlet of the hot salt tank.

[0012] The reheat steam outlet of the boiler is also connected to a reheat steam extraction pipeline. The reheat steam extraction pipeline is connected to the steam inlet of the reheat steam molten salt heater. The reheat steam of the boiler is connected to the steam inlet of the intermediate-pressure cylinder through the reheat steam pipeline. The steam outlets of the intermediate-pressure cylinder and the reheat steam molten salt heater are both connected to the steam inlet of the low-pressure cylinder. The steam outlet of the low-pressure cylinder is connected to the steam inlet of the feed water unit. The condensate outlet of the feed water unit is connected to the boiler feed water inlet pipe.

[0013] In a preferred embodiment of the present utility model, the molten salt heat absorption unit further includes a molten salt electric heater. The molten salt outlets of the main steam molten salt superheater and the reheat steam molten salt heater are both connected to the molten salt inlet of the molten salt electric heater. The molten salt outlet of the molten salt electric heater is connected to the molten salt inlet of the hot salt tank.

[0014] In a preferred embodiment of the present utility model, the molten salt electric heater is connected to the generator or an external power generation system.

[0015] In a preferred embodiment of the present utility model, the feed water unit includes a condenser, a low-pressure heater, a deaerator, a first feed water pump, and a main high-pressure heater that are connected in sequence.

[0016] The pipeline connected to the steam outlet of the molten salt heat release unit further includes a third steam return pipe, which communicates with the high-temperature side inlet of the main high-pressure heater. The steam in the third steam return pipe is used to exchange heat with the condensate in the main high-pressure heater. After the steam in the third steam return pipe exchanges heat and liquefies into condensate, it enters the feed water pipeline between the condenser and the deaerator, and a high-pressure heater valve is provided on the third steam return pipe.

[0017] In a preferred embodiment of the present utility model, the feed water unit includes a condenser, a low-pressure heater, a deaerator, a first feed water pump, a main high-pressure heater, and a secondary high-pressure heater that are connected in sequence.

[0018] The third steam return pipe communicates with the high-temperature side inlet of the secondary high-pressure heater. The steam in the third steam return pipe is used to exchange heat with the condensate in the secondary high-pressure heater. After the steam in the third steam return pipe exchanges heat and liquefies into condensate, it enters the feed water pipeline between the condenser and the deaerator, and a high-pressure heater valve is provided on the third steam return pipe.

[0019] In a preferred embodiment of the present utility model, there is also a fourth steam return pipe in the pipeline connected to the steam outlet of the molten salt heat release unit, and the fourth steam return pipe communicates with the steam pipeline of the heat user.

[0020] In a preferred embodiment of the present utility model, the second steam return pipe communicates with the main steam pipeline, and a first steam combining valve is provided on the second steam return pipe; and / or the second steam return pipe communicates with the reheater steam pipeline, and a second steam combining valve is provided on the second steam return pipe.

[0021] In a preferred embodiment of the present utility model, the molten salt heat release unit includes a superheater, an evaporator, and a preheater. The feed water unit is connected to the preheater, the evaporator, and the superheater in sequence through the feed water branch.

[0022] The molten salt outlet of the hot salt tank communicates with the superheater, the evaporator, and the preheater in sequence.

[0023] In a preferred embodiment of the present utility model, a second feed water pump is provided on the boiler feed water inlet pipe, and a third feed water pump is provided on the feed water branch.

[0024] Due to the adoption of the above technical solutions, the present utility model has the following advantages and positive effects compared with the prior art:

[0025] Operating during the peak shaving stage of a thermal power unit: The boiler operates at a stable combustion and low load. A part of the main steam is extracted and enters the main steam molten salt superheater, the main steam molten salt condenser, and the main steam molten salt subcooler to heat the low-temperature molten salt energy storage. The main steam after heat exchange is cooled into high-pressure feed water and incorporated into the boiler feed water pipeline. There is no cold source loss in this part, and the heat storage efficiency is extremely high. Another part of the main steam operates normally, enters the high-pressure cylinder to do work and generate electricity. The steam flowing out of the high-pressure cylinder flows into the reheat steam inlet pipe and then into the boiler to regenerate the reheat steam. At the same time, the molten salt heat release unit heats the feed water diverted by the feed water unit to generate steam, and the steam flows into the reheat steam inlet pipe to supplement the reheat steam, ensuring the matching of the boiler reheater and superheater and preventing the boiler reheater from overheating. It solves the problem of overheating of the boiler reheater during molten salt energy storage at present, enabling the system to operate smoothly and safely.

[0026] Operating at the peak of the thermal power unit: The molten salt heat absorption unit stops operating, and the molten salt heat release unit operates to heat the feed water diverted by the feed water unit to generate steam. The steam converges into the main steam pipeline and / or the reheat steam pipeline and enters the steam turbine to do work and generate electricity.

[0027] Therefore, the molten salt energy storage coupled thermal power unit flexible peak shaving system provided by the present utility model solves the problem of mismatch in steam flow between the boiler reheater and superheater, completely solves the problem of overheating of the boiler reheater during molten salt energy storage, and enables the boiler to operate safely under different loads. Description of the Drawings

[0028] Figure 1 Schematic diagram of the molten salt energy storage coupled thermal power unit flexible peak shaving system provided by the embodiment of the present utility model Figure 1 ;

[0029] Figure 2 Schematic diagram of the molten salt energy storage coupled thermal power unit flexible peak shaving system provided by the embodiment of the present utility model Figure 2 。

[0030] Description of the reference numerals in the drawings: 1 - Thermal power generation system; 101 - Boiler; 102 - Main steam pipeline; 103 - Main steam extraction pipeline; 104 - Reheat steam pipeline; 105 - Reheat steam extraction pipeline; 106 - High-pressure cylinder; 107 - Intermediate-pressure cylinder; 108 - Low-pressure cylinder; 109 - Condenser; 110 - Low-pressure heater; 111 - Deaerator; 112 - First feed water pump; 113 - Main high-pressure heater; 114 - Auxiliary high-pressure heater; 115 - Boiler feed water pipeline; 116 - Reheat steam inlet pipe; 117 - Generator;

[0031] 2 - Molten salt heat absorption unit; 201 - Main steam molten salt superheater; 202 - Main steam molten salt condenser; 203 - Main steam molten salt subcooler; 204 - Reheat steam molten salt heater; 205 - Molten salt electric heater;

[0032] 3 - Molten salt storage unit; 301 - Cold salt tank; 302 - Hot salt tank;

[0033] 4 - Molten salt heat release unit; 401 - Preheater; 402 - Evaporator; 403 - Superheater;

[0034] 5 - First parallel steam valve; 6 - Reheat steam compensation parallel steam valve; 7 - High - pressure heater valve; 8 - Fourth steam return pipe; 9 - First steam return pipe; 10 - Second steam return pipe; 11 - Third steam return pipe; 12 - Second feed water pump; 13 - Third feed water pump; 14 - Feed water branch. Specific embodiments

[0035] It should be noted that when the thermal power unit is operating normally, the main steam of the boiler enters the high - pressure cylinder to do work and generate electricity, and then returns to the boiler and is heated by the reheater to become the reheated steam of the boiler. After the reheated steam of the boiler does work in the intermediate - pressure cylinder and the low - pressure cylinder and generates electricity, it enters the feed water unit to become boiler feed water, and then enters the boiler and is heated by the superheater to become the main steam of the boiler. In order to improve the peak - shaving ability of the thermal power unit, the thermal power unit is combined with molten salt energy storage. During the low - load peak - shaving stage of the thermal power unit, part of the main steam is extracted to heat the molten salt energy storage to achieve the purpose of reducing the electrical load of the steam turbine, and the other part of the main steam does normal work and generates electricity. As a result, the flow rates of the steam returning to the boiler superheater and the reheater do not match, leading to the problem of overheating of the boiler reheater.

[0036] The present utility model aims at the problem of overheating of the boiler reheater that appears in the current system combining molten salt energy storage and flexible peak - shaving of thermal power units, and provides a molten salt energy storage - coupled flexible peak - shaving system for thermal power units. The steam heated by the molten salt heat release unit is merged with the steam at the outlet of the high - pressure cylinder into the reheated steam inlet pipe to make up for the reheated steam. Compared with the current method of using a steam ejector to send a part of the cooled main steam into the cold steam pipeline, it can adapt to the safe operation of the boiler under different load parameters.

[0037] The following further details a molten salt energy storage - coupled flexible peak - shaving system for thermal power units proposed by the present utility model in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present utility model will be clearer.

[0038] See Figure 1-2, a molten salt energy storage coupled thermal power unit flexible peak shaving system, including a thermal power generation system 1 and a molten salt energy storage system. The thermal power generation system 1 includes a boiler 101, a feed water unit, a steam turbine, and a generator 117. The steam turbine includes a high-pressure cylinder 106, an intermediate-pressure cylinder 107, and a low-pressure cylinder 108. The main steam outlet of the boiler 101 is respectively connected to a main steam pipeline 102 and a main steam extraction pipeline 103. The reheated steam outlet of the boiler 101 is connected to a reheated steam pipeline 104. The molten salt energy storage system includes a molten salt heat absorption unit 2, a molten salt heat release unit 4, and a molten salt storage unit 3. The molten salt storage unit 3 includes a cold salt tank 301 and a hot salt tank 302. The molten salt heat absorption unit 2 includes a main steam molten salt superheater 201, a main steam molten salt condenser 202, and a main steam molten salt subcooler 203;

[0039] The main steam pipeline 102 is connected to the steam inlet of the high-pressure cylinder 106. The steam outlet of the high-pressure cylinder 106 is connected to a reheated steam inlet pipe 116. The reheated steam inlet pipe 116 is connected to the reheated steam inlet of the boiler 101. The main steam extraction pipeline 103 is sequentially connected to the main steam molten salt superheater 201, the main steam molten salt condenser 202, and the main steam molten salt subcooler 203. The condensate outlet of the main steam molten salt subcooler 203 is connected to the boiler 101 through a boiler 101 feed water inlet pipe. A second feed water pump 12 is provided on the boiler 101 feed water inlet pipe;

[0040] The molten salt outlet of the cold salt tank 301 is sequentially connected to the main steam molten salt subcooler 203, the main steam molten salt condenser 202, the main steam molten salt superheater 201, and the hot salt tank 302;

[0041] The molten salt outlet of the hot salt tank 302 is connected to the molten salt inlet of the molten salt heat release unit 4. The molten salt outlet of the molten salt heat release unit 4 is connected to the molten salt inlet of the cold salt tank 301. The feed water unit is connected to the condensate inlet of the molten salt heat release unit 4 through a feed water branch 14. The pipeline connected to the steam outlet of the molten salt heat release unit 4 includes a first steam return pipe 9 and a second steam return pipe 10. The first steam return pipe 9 is connected to the reheated steam inlet pipe 116. Preferably, a reheated steam compensation parallel valve 6 is provided on the first steam return pipe 9. The second steam return pipe 10 is connected to the main steam pipeline 102 and / or the reheated steam pipeline 104. The second steam return pipe 10 is connected to the main steam pipeline 102, and a first parallel valve 5 is provided on the second steam return pipe 10; and / or the second steam return pipe 10 is connected to the reheated steam pipeline 104, and a second parallel valve is provided on the second steam return pipe 10. In this embodiment, further preferably, the second steam return pipe 10 is connected to the main steam pipeline 102, and higher-quality steam can be obtained to improve the power generation efficiency.

[0042] Operation during the peak shaving stage of a thermal power unit: The boiler 101 operates at a stable combustion and low load. A part of the main steam is extracted and flows successively through the main steam molten salt superheater 201, the main steam molten salt condenser 202, and the main steam molten salt subcooler 203 via the main steam extraction pipeline 103 to heat the low-temperature molten salt energy storage. The main steam after heat exchange is cooled into high-pressure feed water, flows into the feed water pipeline of the boiler 101, and enters the boiler 101. There is no cold source loss in this part, and the heat storage efficiency is extremely high. Another part of the main steam operates normally, enters the high-pressure cylinder 106 via the main steam pipeline 102 to do work and generate electricity. The steam flowing out of the high-pressure cylinder 106 flows into the reheater steam inlet pipe 116 and then into the boiler 101 to regenerate the reheater steam. At the same time, the molten salt heat release unit 4 operates, and the reheater steam compensation parallel valve 6 is opened. The high-temperature molten salt flowing in the molten salt heat release unit 4 heats the feed water shunted by the feed water unit to generate steam. The steam flows into the reheater steam inlet pipe 116 via the first steam return pipe 9 to make up the reheater steam, ensuring the matching of the reheater and superheater of the boiler 101 and preventing the overheating of the reheater of the boiler 101.

[0043] Molten salt energy storage during the peak shaving stage of a thermal power unit: The low-temperature molten salt in the low-salt tank flows successively through the main steam molten salt subcooler 203, the main steam molten salt condenser 202, and the main steam molten salt superheater 201, absorbs the heat of the main steam of the boiler 101, and the high-temperature molten salt after temperature rise flows into the hot salt tank 302 to store heat energy.

[0044] Operation at the peak of a thermal power unit: The molten salt heat absorption unit 2 stops operating. The thermal power unit can operate from low load to full load according to the actual electricity demand. The reheater steam compensation parallel valve 6 is closed, and the molten salt heat release unit 4 operates. According to the actual electricity demand, the high-temperature molten salt in the hot salt tank 302 flows into the molten salt heat release unit 4 to heat the feed water shunted by the feed water unit to generate steam. The steam converges to the main steam pipeline 102 and / or the reheater steam pipeline 104 and enters the steam turbine to do work and generate electricity, that is, the molten salt energy storage system participates in the operation of the thermal power unit to jointly generate electricity, responds to the actual electricity demand, and the low-temperature molten salt flowing out of the molten salt heat release unit 4 flows into the low-temperature molten salt storage.

[0045] Since the molten salt energy storage improves the peak shaving ability of the thermal power unit, that is, extracting the main steam to heat the molten salt for energy storage, while reducing the electrical load of the steam turbine, the steam from the molten salt heat release unit 2 converges with the steam from the high-pressure cylinder 106 to the boiler 101 to generate reheater steam, resulting in the reheater steam flow at the outlet of the boiler 101 being greater than the main steam flow in the high-pressure cylinder 106. Therefore, there is a large difference in the intake air volume between the high-pressure cylinder 106 and the intermediate-pressure cylinder 107, which will cause the problem of thrust imbalance between the high and intermediate-pressure cylinders 107 of the steam turbine. Usually, to solve the problem of thrust imbalance between the high and intermediate-pressure cylinders 107 of the steam turbine, the main steam is desuperheated and depressurized and then merged into the reheater steam inlet pipe 116. At this time, the heat loss of this method is large and it is very uneconomical.

[0046] While solving the problem of overheating of the reheater of the boiler 101, this embodiment also solves the problem of pressure imbalance between the high and intermediate pressure cylinders of the steam turbine. By extracting part of the reheated steam to heat the low-temperature molten salt and allowing the other part of the reheated steam to normally enter the intermediate and low-pressure cylinders 108 of the steam turbine to generate electricity, the pressure of the reheated steam entering the intermediate pressure cylinder 107 can be reduced. The specific implementation is as follows:

[0047] The molten salt heat absorption unit 2 further includes a reheated steam molten salt heater 204. The molten salt outlet of the cold salt tank 301 is respectively connected to the molten salt inlets of the reheated steam molten salt heater 204 and the main steam molten salt subcooler 203. The molten salt outlets of the reheated steam molten salt heater 204 and the main steam molten salt superheater 201 are both connected to the molten salt inlet of the hot salt tank 302;

[0048] The reheated steam outlet of the boiler 101 is also connected to a reheated steam extraction pipeline 105. The reheated steam extraction pipeline 105 is connected to the steam inlet of the reheated steam molten salt heater 204. The reheated steam of the boiler 101 is connected to the steam inlet of the intermediate pressure cylinder 107 through a reheated steam pipeline 104. The steam outlets of the intermediate pressure cylinder 107 and the reheated steam molten salt heater 204 are both connected to the steam inlet of the low-pressure cylinder 108. The steam outlet of the low-pressure cylinder 108 is connected to the steam inlet of the feed water unit. The condensate outlet of the feed water unit is connected to the feed water inlet pipe of the boiler 101.

[0049] Extracting part of the reheated steam through the reheated steam extraction pipeline 105 to enter the reheated steam molten salt heater 204 to heat the low-temperature molten salt can also achieve the purpose of molten salt energy storage. The reheated steam for heating the low-temperature molten salt enters the low-pressure cylinder 108 to generate electricity; the other part of the reheated steam enters the intermediate pressure cylinder 107 of the steam turbine through the reheated steam pipeline 104 to generate electricity. The reheated steam flowing out of the intermediate pressure cylinder 107 converges with the reheated steam flowing out of the reheated steam molten salt heater 204 and jointly enters the low-pressure cylinder 108 to generate electricity. The steam flowing out of the low-pressure cylinder 108 enters the feed water unit, is condensed and preheated by the feed water unit, and then enters the feed water inlet pipe of the boiler 101, and then enters the boiler 101 to reproduce the main steam. In this way, by allowing part of the reheated steam to enter the added reheated steam molten salt heater 204 to heat the low-temperature molten salt for energy storage, the flow rate of the reheated steam entering the intermediate pressure cylinder 107 can be reduced, the thrust balance of the steam turbine can be achieved, and the reheated steam after heating the molten salt is depressurized and then enters the low-pressure cylinder 108 to generate electricity. Compared with the method of reducing the temperature and pressure of the main steam and then merging it into the reheated steam inlet pipe 116 to solve the problem of pressure imbalance between the high and intermediate pressure cylinders of the steam turbine, the heat loss is greatly reduced, and this technical solution can solve the problems of overheating of the boiler reheater and pressure imbalance in the steam turbine cylinder simultaneously.

[0050] In one preferred embodiment, the molten salt heat absorption unit 2 further includes a molten salt electric heater 205. The molten salt outlets of the main steam molten salt superheater 201 and the reheated steam molten salt heater 204 are both connected to the molten salt inlet of the molten salt electric heater 205, and the molten salt outlet of the molten salt electric heater 205 is connected to the molten salt inlet of the hot salt tank 302.

[0051] Using the molten salt electric heater 205 can further heat the molten salt heated by the main steam and the reheated steam, raise the temperature of the molten salt to a higher level, and then store it in the hot salt tank 302 to achieve the purpose of deep peak shaving.

[0052] Furthermore, the molten salt electric heater 205 is connected to the generator 117. During deep peak shaving operation, the molten salt electric heater 205 is turned on. By raising the temperature of the molten salt through the molten salt electric heater 205, the electricity generated in excess by the steam turbine can be consumed at the same time, reducing the on-grid power of the thermal power generation system 1 to 0, achieving the purpose of deep peak shaving and earning more peak shaving benefits. In addition, the molten salt electric heating can also be connected to new energy power generation such as wind power or solar power to absorb the abandoned electricity, or it can be an external generator, etc.

[0053] In another preferred embodiment, the feed water unit includes a condenser 109, a low-pressure heater 110, a deaerator 111, a first feed water pump 112, and a main high-pressure heater 113 that are connected in sequence; wherein the feed water branch 14 is a pipeline branched from the outlet of the deaerator 111 and is used to communicate with the condensate inlet of the molten salt heat release unit 4. A third feed water pump 13 is provided on the feed water branch 14;

[0054] The pipeline connected to the steam outlet of the molten salt heat release unit 4 further includes a third steam return pipe 11. A high-pressure heater valve 7 is provided on the third steam return pipe 11. The third steam return pipe 11 communicates with the high-temperature side inlet of the main high-pressure heater 113. The steam in the third steam return pipe 11 is used to exchange heat with the condensate in the main high-pressure heater 113. After the steam in the third steam return pipe 11 exchanges heat, it flows out from the high-temperature side outlet of the main high-pressure heater 113 and can continue to exchange heat with the condensate in the low-pressure heater 110, or can be condensed, and finally enters the feed water pipeline between the condenser 109 and the deaerator 111 after being liquefied into condensate.

[0055] In order to prevent the steam in the third steam return pipe 11 from having inconsistent parameters with the main high-pressure heater 113 in the feed water unit, a secondary high-pressure heater 114 is added after the main high-pressure heater 113, that is, the feed water unit includes a condenser 109, a low-pressure heater 110, a deaerator 111, a first feed water pump 112, a main high-pressure heater 113, and a secondary high-pressure heater 114 that are connected in sequence; similarly, the feed water branch 14 is a pipeline branched from the outlet of the deaerator 111 and is used to communicate with the condensate inlet of the molten salt heat release unit 4. A third feed water pump 13 is provided on the feed water branch 14;

[0056] The third steam return pipe 11 is connected to the high-temperature side inlet of the auxiliary high-pressure heater 114. The steam in the third steam return pipe 11 is used to exchange heat with the condensate water in the auxiliary high-pressure heater 114. After the steam in the third steam return pipe 11 exchanges heat, it flows out from the high-temperature side outlet of the auxiliary high-pressure heater 114, and can continue to exchange heat with the condensate water in the high-pressure heater and / or the low-pressure heater 110, or can be directly condensed. But finally, it is liquefied into condensate water and enters the feed water pipe between the condenser 109 and the deaerator 111, becoming the feed water for the boiler 101. The existence of the auxiliary high-pressure heater 114 can make it independent from the main high-pressure heater 113 of the original unit, without the need to carry out complex and high-cost renovations on the main high-pressure heater 113. The auxiliary high-pressure heater can be selectively opened and closed and only used as a medium passage, and the two can actually operate without interference, and the thermal power unit can still ensure normal and stable operation.

[0057] Regardless of whether the feed water unit contains the auxiliary high-pressure heater 114, the steam heated in the molten salt heat release unit 4 passes through the third steam return pipe to heat the feed water of the feed water unit, indirectly generating electricity, increasing the power of the thermal power generation system 1, and earning the peak-valley electricity price difference.

[0058] In another embodiment, there is also a fourth steam return pipe 8 in the pipe connected to the steam outlet of the molten salt heat release unit 4. The fourth steam return pipe 8 is connected to the steam pipe of the heat user, increasing the supply source and supply volume of industrial steam or heating steam.

[0059] Preferably, the molten salt heat release unit 4 includes a superheater 403, an evaporator 402, and a preheater 401. The feed water unit is sequentially connected to the preheater 401, the evaporator 402, and the superheater 403 through the feed water branch 14; the molten salt outlet of the hot salt tank 302 is sequentially connected to the superheater 403, the evaporator 402, and the preheater 401.

[0060] The operation method of the molten salt energy storage coupled thermal power unit flexibility peak shaving system in this embodiment:

[0061] Peaking stage: Close the first parallel steam valve 5 and the high-pressure heater valve 7. When the thermal power unit operates at low load, 20% of the supercritical parameter main steam of the thermal power plant is extracted and enters the main steam molten salt superheater 201, the main steam molten salt condenser 202, and the main steam molten salt subcooler 203 through the main steam extraction pipeline 103. The molten salt is heated to 380 °C, and the main steam is cooled into high-pressure feed water. Through the first feed water pump 112, it enters the feed water inlet pipe of the boiler 101 and then enters the superheater of the boiler 101 to regenerate the main steam of the boiler 101. There is no cold source loss in this part, and the heat storage efficiency is extremely high. In addition, part of the reheated steam of the boiler 101 is extracted and enters the reheated steam molten salt heater 204 through the reheated steam extraction pipeline 105. At the same time, open the reheated steam compensation parallel steam valve 6. The steam flowing out of the molten salt heat release unit 4 (the deaerated water flowing out of the deaerator 111 is lifted by the third feed water pump 13, enters the preheater 401, the evaporator 402, and the superheater 403, and is heated by the high-temperature molten salt) and the steam flowing out after doing work in the high-pressure cylinder 106 through the main steam pipeline 102 are merged and flow into the reheated steam inlet pipe 116, and then flow into the reheater of the boiler 101 to ensure the matching of the reheater flow and the superheater, and the reheater of the boiler 101 does not overheat. After the reheated steam heats the low-temperature molten salt in the reheated steam molten salt heater 204, it merges with the steam flowing into the intermediate-pressure cylinder 107 of the steam turbine through the reheated steam pipeline 104 to do work and generate electricity, and then flows into the low-pressure cylinder 108 of the steam turbine to do work and generate electricity. Then, it passes through the condenser 109, the low-pressure heater 110, the deaerator 111, the second feed water pump 12, the main high-pressure heater 113, and the auxiliary high-pressure heater 114, and converges into the superheater of the boiler 101 to regenerate the main steam of the boiler 101. During this period, the boiler 101 operates at low load, that is, the main steam enters the high-pressure cylinder 106 through the main steam pipeline 102 to do work and generate electricity, and the reheated steam enters the intermediate-pressure cylinder 107 through the reheated steam pipeline 104 to do work and generate electricity.

[0062] Peaking stage molten salt energy storage: A part of the low-temperature molten salt in the cold salt tank 301 flows through the main steam molten salt subcooler 203, the main steam molten salt condenser 202, and the main steam molten salt superheater 201 and is heated by the main steam. Another part flows through the reheated steam molten salt heater 204 and is heated by the reheated steam. The two parts of the heated molten salt are merged into the molten salt electric heater 205 and continue to heat the molten salt to 560 °C, and then flow into the hot salt tank 302 for storage. Not only when the power grid demand is at a low ebb and the thermal power plant operates at low load, the steam is used to heat the molten salt for energy storage, but also the molten salt electric heater 205 can consume the electricity generated more by the steam turbine, reducing the on-grid power of the thermal power plant to zero, achieving the purpose of deep peaking and earning peaking benefits.

[0063] Peak stage of thermal power plant: The molten salt heat absorption unit 2 does not operate, the reheated steam compensation and parallel connection valve 6 is closed, and the high-temperature molten salt in the hot salt tank 302 flows into the molten salt heat release unit 4. In the molten salt heat release unit 4, the deaerated water is heated into supercritical parameter steam. The first parallel connection valve 5 and / or the second parallel connection valve are opened, and the steam is merged into the main steam pipeline 102 and / or the reheated steam pipeline 104 to enter the steam turbine for power generation; or the high-pressure heater valve 7 is opened to heat the feed water in the auxiliary high-pressure heater 114 for indirect power generation, increasing the power generation capacity of the power plant and earning the peak-valley electricity price difference; at the same time, if additional industrial steam or heating steam needs to be supplied, the steam generated by the molten salt heat release can also be merged into the steam pipeline of off-site heat users to increase the steam supply of the power plant.

[0064] In this embodiment, the steam heated by the molten salt heat release unit 44 is designed to have four outlets. Except for the fourth steam return pipe 8 that connects to the heat user pipeline to supply heating for the thermal power plant or supply industrial steam or heating steam off-site; the others return to the thermal power generation system 1. The first steam return pipe 9 connects to the reheated steam inlet pipe 116 to supplement the reheated steam; the second steam return pipe 10 connects to the main steam pipeline 102 and / or the reheated steam pipeline 104 to enter the steam turbine for power generation; the third steam return pipe 11 connects to the high-temperature side inlet of the auxiliary high-pressure heater 114 to heat the feed water of the boiler 101 for indirect power generation, increasing the power generation capacity of the power plant and earning the peak-valley electricity price difference. The above constitutes a steam regulation system. By adjusting the parameters of the third feed water pump 13, the feed water parameters entering the preheater 401 can be adjusted. After being heated by the molten salt, four different parameter steams can be obtained. When it is necessary to connect to the reheated steam inlet pipe 116, adjust the output of the third feed water pump 13 so that the steam parameters flowing out of the superheater 403 are the same as those in the reheated steam inlet pipe 116 for convenient parallel connection; when it is necessary to merge into the main steam, adjust the output of the third feed water pump 13, and close the reheated steam compensation and parallel connection valve 6, the high-pressure heater valve 7, and the second parallel connection valve so that the steam parameters after being heated by the superheater 403 are the same as the main steam parameters for convenient parallel connection; when it is necessary to merge into the reheated steam, adjust the output of the third feed water pump 13, and close the reheated steam compensation and parallel connection valve 6, the high-pressure heater valve 7, and the first parallel connection valve 5 so that the steam parameters after being heated by the superheater 403 are the same as the reheated steam parameters for convenient parallel connection; when it is necessary for the auxiliary high-pressure heater 114 to heat the feed water of the boiler 101, by adjusting the parameters of the third feed water pump 13 and the steam parameters at the outlet of the superheater 403, the corresponding steam can also be obtained. The entire molten salt heat release unit 4 has strong adjustment ability and can adapt to parameters with different requirements. Of course, in actual implementation, except for the steam parameters in the reheated steam inlet pipe 116 that must be selected, any one of the other four steam parameters can be selected for application.

[0065] The embodiments of the present utility model have been described in detail above in conjunction with the accompanying drawings. However, the present utility model is not limited to the above embodiments. Even if various changes are made to the present utility model, provided that these changes fall within the scope of the claims of the present utility model and its equivalent technologies, they still fall within the protection scope of the present utility model.

Claims

1. A molten salt energy storage coupled thermal power unit flexibility peak shaving system, comprising a thermal power generation system and a molten salt energy storage system. The thermal power generation system includes a boiler, a feed water unit, a steam turbine and a generator. The steam turbine includes a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder. The main steam outlet of the boiler is connected to a main steam pipeline, and the reheated steam outlet of the boiler is connected to a reheated steam pipeline. The molten salt energy storage system includes a molten salt heat absorption unit, a molten salt heat release unit and a molten salt storage unit. The molten salt storage unit includes a cold salt tank and a hot salt tank. The molten salt heat absorption unit includes a main steam molten salt superheater, a main steam molten salt condenser and a main steam molten salt subcooler. Characterized in that, The main steam outlet of the boiler is also connected to a main steam extraction pipeline, The main steam pipeline is connected to the steam inlet of the high-pressure cylinder, the steam outlet of the high-pressure cylinder is connected to a reheated steam inlet pipe, and the reheated steam inlet pipe is connected to the reheated steam inlet of the boiler; the main steam extraction pipeline is sequentially connected to the main steam molten salt superheater, the main steam molten salt condenser and the main steam molten salt subcooler, and the condensate outlet of the main steam molten salt subcooler is connected to the boiler through a boiler feed water inlet pipe; The molten salt outlet of the cold salt tank is sequentially connected to the main steam molten salt subcooler, the main steam molten salt condenser, the main steam molten salt superheater and the hot salt tank; The molten salt outlet of the hot salt tank is connected to the molten salt inlet of the molten salt heat release unit, the molten salt outlet of the molten salt heat release unit is connected to the molten salt inlet of the cold salt tank, the feed water unit is connected to the condensate inlet of the molten salt heat release unit through a feed water branch, and the pipeline connected to the steam outlet of the molten salt heat release unit includes a first steam return pipe and a second steam return pipe. The first steam return pipe is connected to the reheated steam inlet pipe; the second steam return pipe is connected to the main steam pipeline and / or the reheated steam pipeline; A reheated steam compensation parallel valve is provided on the first steam return pipe.

2. The molten salt energy storage coupled thermal power unit flexibility peak shaving system according to claim 1, Characterized in that, The molten salt heat absorption unit further includes a reheated steam molten salt heater. The molten salt outlet of the cold salt tank is respectively connected to the molten salt inlets of the reheated steam molten salt heater and the main steam molten salt subcooler, and the molten salt outlets of the reheated steam molten salt heater and the main steam molten salt superheater are both connected to the molten salt inlet of the hot salt tank; The reheated steam outlet of the boiler is also connected to a reheated steam extraction pipeline. The reheated steam extraction pipeline is connected to the steam inlet of the reheated steam molten salt heater. The reheated steam of the boiler is connected to the steam inlet of the intermediate-pressure cylinder through the reheated steam pipeline. The steam outlets of the intermediate-pressure cylinder and the reheated steam molten salt heater are both connected to the steam inlet of the low-pressure cylinder. The steam outlet of the low-pressure cylinder is connected to the steam inlet of the feed water unit, and the condensate outlet of the feed water unit is connected to the boiler feed water inlet pipe.

3. The molten salt energy storage coupled thermal power unit flexibility peak shaving system according to claim 2, Characterized in that, The molten salt heat absorption unit further includes a molten salt electric heater. The molten salt outlets of the main steam molten salt superheater and the reheated steam molten salt heater are both connected to the molten salt inlet of the molten salt electric heater, and the molten salt outlet of the molten salt electric heater is connected to the molten salt inlet of the hot salt tank.

4. The molten salt energy storage coupled thermal power unit flexibility peak shaving system according to claim 3, wherein, the molten salt electric heater is connected to the generator or an external power generation system.

5. The molten salt energy storage coupled thermal power unit flexibility peak shaving system according to claim 1, wherein, the feed water unit includes a condenser, a low-pressure heater, a deaerator, a first feed water pump, and a main high-pressure heater that are connected in sequence; The pipeline connected to the steam outlet of the molten salt heat release unit further includes a third steam return pipe. The third steam return pipe is connected to the high-temperature side inlet of the main high-pressure heater. The steam in the third steam return pipe is used to exchange heat with the condensed water in the main high-pressure heater. After the steam in the third steam return pipe exchanges heat and liquefies into condensed water, it enters the feed water pipeline between the condenser and the deaerator, and a high-pressure heater valve is provided on the third steam return pipe.

6. The molten salt energy storage coupled thermal power unit flexibility peak shaving system according to claim 5, wherein, the feed water unit includes a condenser, a low-pressure heater, a deaerator, a first feed water pump, a main high-pressure heater, and a secondary high-pressure heater that are connected in sequence; The third steam return pipe is connected to the high-temperature side inlet of the secondary high-pressure heater. The steam in the third steam return pipe is used to exchange heat with the condensed water in the secondary high-pressure heater. After the steam in the third steam return pipe exchanges heat and liquefies into condensed water, it enters the feed water pipeline between the condenser and the deaerator, and a high-pressure heater valve is provided on the third steam return pipe.

7. The molten salt energy storage coupled thermal power unit flexibility peak shaving system according to claim 1, wherein, There is also a fourth steam return pipe in the pipeline connected to the steam outlet of the molten salt heat release unit. The fourth steam return pipe is connected to the heat user steam pipeline.

8. The molten salt energy storage coupled thermal power unit flexibility peak shaving system according to claim 1, wherein, the second steam return pipe is connected to the main steam pipeline, and a first steam merging valve is provided on the second steam return pipe; and / or the second steam return pipe is connected to the reheated steam pipeline, and a second steam merging valve is provided on the second steam return pipe.

9. The molten salt energy storage coupled thermal power unit flexibility peak shaving system according to claim 1, wherein, the molten salt heat release unit includes a superheater, an evaporator, and a preheater. The feed water unit is connected to the preheater, the evaporator, and the superheater in sequence through the feed water branch; The molten salt outlet of the hot salt tank is connected to the superheater, the evaporator, and the preheater in sequence.

10. The molten salt energy storage coupled thermal power unit flexibility peak shaving system according to claim 1, wherein, a second feed water pump is provided on the boiler feed water inlet pipe, and a third feed water pump is provided on the feed water branch.

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