A flexible peak-shaving and frequency regulation system for coal-fired power generating units and its operation method

Abstract

A flexible peak-shaving and frequency regulation system and operation method for coal-fired power generating units are disclosed, relating to the field of peak-shaving technology for coal-fired power generating units. In the initial stage of energy storage, the peak-shaving rate of the unit is increased through an electrode boiler. In the initial stage of energy release, the load-up rate of the unit is increased by directly introducing superheated steam into the unit, thus achieving synergy between peak-shaving and frequency regulation. While ensuring the safety of unit operation, the peak-shaving capacity of the coal-fired power generating unit is increased, thereby avoiding problems such as reduced unit lifespan, decreased system thermal efficiency, and increased coal consumption caused by peak-shaving and frequency regulation.

Description

Technical Field

[0001] This invention relates to the field of peak shaving technology for coal-fired power generating units, specifically to a flexible peak shaving and frequency regulation system and operation method for coal-fired power generating units. Background Technology

[0002] Since the "dual carbon target" was proposed, my country's installed capacity of renewable energy has increased rapidly. However, due to the volatility, intermittency, and randomness of new energy power generation, high-stability power sources are needed for peak shaving, in which coal-fired power plays a crucial role. However, the thermodynamic economics of coal-fired power units decrease significantly when operating at low loads. Currently, there are many methods to improve the flexibility of coal-fired power units, such as low-load stable combustion technology, wide-load denitrification technology, turbine equipment modification technology, and thermal energy storage technology. Among these, thermal energy storage can store excess energy when the coal-fired power unit is operating at reduced load and release the stored energy when the load increases. This not only achieves the goals of peak shaving and frequency regulation, but also provides scientific energy conservation and emission reduction effects.

[0003] Molten salt thermal energy storage is a commonly used method for thermal energy storage in coal-fired power units. It boasts advantages such as high thermal density, low viscosity, low cost, and large scale, and is widely used in the thermal energy storage field. Patent CN114992613A proposes a steam-molten salt coupled energy storage deep peak-shaving system. In the energy storage phase, low-temperature molten salt is heated by extracting main steam or reheat steam, thereby reducing the steam flow to the turbine and lowering the power generation. In the energy release phase, feedwater is heated to steam by the high-temperature molten salt, which then drives the turbine to perform work, increasing the power generation. Patent CN114484404A proposes a molten salt energy storage system. In the energy storage phase, a molten salt electric heater heats low-temperature molten salt, transforming it into high-temperature molten salt, which is then stored in a high-temperature molten salt storage tank. In the energy release phase, the high-temperature molten salt heats deoxygenated water to become saturated steam, which is then sent to an external steam network or drives a turbine to perform work. However, existing coal-fired power plant molten salt thermal energy storage technologies have many drawbacks. For example, traditional coal-fired power plant coupled with molten salt thermal energy storage systems often use steam extraction to heat the molten salt or resistance-type molten salt heaters. The former has a slow response speed, resulting in low frequency regulation efficiency and insignificant frequency regulation effects, while the latter directly utilizes electrical energy for peak shaving, offering fast and strong frequency regulation capabilities, but converting electrical energy into molten salt thermal energy leads to significant energy losses. Therefore, there is an urgent need to develop a coal-fired power plant coupled with thermal energy storage system that boasts high reliability, strong peak shaving capabilities, and fast frequency regulation speed. Summary of the Invention

[0004] In order to overcome the shortcomings of the above technologies, this invention provides a flexible peak-shaving and frequency regulation system and its operation method for coal-fired power generating units that effectively solves the problems of existing coal-fired power-coupled thermal energy storage peak-shaving systems, such as single function, weak frequency regulation capability, short service life, and low system efficiency.

[0005] The technical solution adopted by this invention to overcome its technical problems is:

[0006] A flexible peak-shaving and frequency regulation system for a coal-fired power generating unit includes:

[0007] The molten salt heater has its steam inlet end connected to the main steam pipeline of the coal-fired power generation system, and its steam outlet end connected to the boiler drain line.

[0008] A low-temperature molten salt storage tank, the outlet of which is connected to the molten salt inlet of a molten salt heater;

[0009] A high-temperature molten salt storage tank, the inlet of which is connected to the molten salt outlet of a molten salt heater;

[0010] The steam generator has its molten salt inlet connected to the outlet of a high-temperature molten salt storage tank, its molten salt outlet connected to the inlet of a low-temperature molten salt storage tank, and its steam outlet connected to a reheat steam pipeline.

[0011] The steam storage tank has its inlet end connected to the steam outlet end of the electrode boiler, the inlet end of the electrode boiler is connected to the water supply tank, and its outlet end is connected to the steam inlet end of the steam generator.

[0012] The molten salt exothermic device has its molten salt outlet connected to the inlet of a low-temperature molten salt storage tank, its molten salt inlet connected to the outlet of a high-temperature molten salt storage tank, its water-side outlet connected to a boiler feedwater pipeline, and its water-side inlet connected to a deaerator pipeline.

[0013] Furthermore, the steam inlet of the molten salt heater is connected to the main steam pipeline of the coal-fired power generation system via the main steam control valve.

[0014] Furthermore, the inlet of the high-temperature molten salt storage tank is connected to the molten salt outlet of the molten salt heater via a high-temperature molten salt pump.

[0015] Furthermore, the molten salt outlet of the steam generator is connected to the inlet of the cryogenic molten salt storage tank via the No. 1 cryogenic molten salt pump.

[0016] Furthermore, the inlet end of the electrode boiler is connected to the makeup water tank via a makeup water pump.

[0017] Furthermore, the molten salt outlet of the molten salt exothermic device is connected to the inlet of the cryogenic molten salt storage tank via the No. 2 cryogenic molten salt pump.

[0018] Furthermore, the water-side inlet of the molten salt exothermic device is connected to the deoxygenated water pipeline via a deoxygenated water supply pump.

[0019] A method for operating a flexible peak-shaving and frequency regulation system for a coal-fired power generating unit, characterized by:

[0020] Energy storage phase operation method:

[0021] When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2, the electrode boiler, the water supply pump, and the main steam control valve are opened at the same time.

[0022] Electrode boilers consume the electrical energy generated by generators to heat the makeup water in the makeup water tank into saturated steam, which is then sent to the steam storage tank, reducing the output power of coal-fired power units to Ws3.

[0023] The low-temperature molten salt in the low-temperature molten salt storage tank is transported to the molten salt heater by the high-temperature molten salt pump. In the molten salt heater, the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank for storage. The main steam after heat exchange is sent to the boiler feedwater.

[0024] When the output power of the coal-fired power unit drops to Ws4, the electrode boiler and the water supply pump are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank is used for deep peak shaving to Ws2.

[0025] Operation method of the energy release stage:

[0026] At the same time, the outlet valve of the steam storage tank and the No. 1 low-temperature molten salt pump are opened. The saturated steam in the steam storage tank is heated to superheated steam by the high-temperature molten salt after passing through the steam generator. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity.

[0027] When the outlet pressure of the steam storage tank drops to n times the maximum working pressure, close the outlet valve of the steam storage tank, and start the deoxygenated water supply pump and the No. 2 low-temperature molten salt pump. Use the high-temperature molten salt to heat the deoxygenated water to continue increasing the load.

[0028] Preferably, Ws3 is 1.2-1.5 times Ws2, Ws4 is 1.1-1.2 times Ws2, and n takes the value of 0.2-0.5.

[0029] The beneficial effects of this invention are as follows: Compared with existing single thermal storage systems, this system increases the peak-shaving rate of the unit through an electrode boiler in the initial stage of energy storage, and increases the load-up rate of the unit by directly introducing superheated steam into the unit in the initial stage of energy release, thus realizing the synergy of peak-shaving and frequency regulation of the unit; while ensuring the safe operation of the unit, it increases the peak-shaving capacity of the coal-fired power unit, thereby avoiding problems such as the reduction of unit operating life, the decrease in system thermal efficiency, and the increase in coal consumption rate caused by peak-shaving and frequency regulation. Attached Figure Description

[0030] Figure 1 This is a system structure diagram of the present invention;

[0031] In the diagram, 101. Main steam control valve; 102. Molten salt heater; 103. High-temperature molten salt pump; 104. High-temperature molten salt storage tank; 105. Steam generator; 106. No. 1 low-temperature molten salt pump; 107. Molten salt heat exchanger; 108. No. 2 low-temperature molten salt pump; 109. Low-temperature molten salt storage tank; 110. Deoxygenated water supply pump; 201. Makeup water tank; 202. Makeup water pump; 203. Electrode boiler; 204. Steam storage tank. Detailed Implementation

[0032] The following is in conjunction with the appendix Figure 1 The present invention will be further described below.

[0033] A flexible peak-shaving and frequency regulation system for a coal-fired power generating unit includes:

[0034] A molten salt heater 102 has its steam inlet connected to the main steam pipeline of the coal-fired power generation system and its steam outlet connected to the boiler drain line. A low-temperature molten salt storage tank 109 has its outlet connected to the molten salt inlet of the molten salt heater 102. A high-temperature molten salt storage tank 104 has its inlet connected to the molten salt outlet of the molten salt heater 102. A steam generator 105 has its molten salt inlet connected to the outlet of the high-temperature molten salt storage tank 104 and its molten salt outlet connected to the inlet of the low-temperature molten salt storage tank 109. The steam outlet is connected to the reheat steam pipeline; the steam storage tank 204 has its inlet connected to the steam outlet of the electrode boiler 203, the inlet of the electrode boiler 203 is connected to the makeup water tank 201, and its outlet is connected to the steam inlet of the steam generator 105; the molten salt heat exchanger 107 has its molten salt outlet connected to the inlet of the low-temperature molten salt storage tank 109, its molten salt inlet connected to the outlet of the high-temperature molten salt storage tank 104, its water-side outlet connected to the boiler feedwater pipeline, and its water-side inlet connected to the deaerator pipeline.

[0035] During the energy storage phase, the unit can quickly reduce its load by coupling the electrode boiler with the molten salt thermal storage. During the energy release phase, the unit can quickly increase its load by heating the saturated steam and deoxygenated water with molten salt. This enables rapid, deep, and flexible peak shaving, thereby avoiding problems such as reduced unit lifespan, decreased system thermal efficiency, and increased coal consumption caused by peak shaving and frequency regulation.

[0036] In one embodiment of the present invention, the steam inlet end of the molten salt heater 102 is connected to the main steam pipeline of the coal-fired power generation system via a main steam control valve 101. By providing the main steam control valve 101, it is convenient to control whether main steam is supplied to the molten salt heater 102.

[0037] In one embodiment of the present invention, the inlet end of the high-temperature molten salt storage tank 104 is connected to the molten salt outlet end of the molten salt heater 102 via a high-temperature molten salt pump 103. By providing the high-temperature molten salt pump 103, it can be ensured that the molten salt in the molten salt heater 102 is delivered into the high-temperature molten salt storage tank 104.

[0038] The molten salt outlet of the steam generator 105 is connected to the inlet of the cryogenic molten salt storage tank 109 via a cryogenic molten salt pump 106. By installing the cryogenic molten salt pump 106, it is ensured that the molten salt in the steam generator 105 is delivered into the cryogenic molten salt storage tank 109.

[0039] The inlet of the electrode boiler 203 is connected to the water supply tank 201 via a water supply pump 202. By setting up the water supply pump 202, it can be ensured that the water in the water supply tank 201 is delivered into the electrode boiler 203.

[0040] The molten salt outlet of the molten salt exotherm 107 is connected to the inlet of the cryogenic molten salt storage tank 109 via a second cryogenic molten salt pump 108. By installing the second cryogenic molten salt pump 108, it can be ensured that the molten salt in the molten salt exotherm 107 is delivered into the cryogenic molten salt storage tank 109.

[0041] The water-side inlet of the molten salt exothermic generator 107 is connected to the deoxygenated water pipeline via a deoxygenated water supply pump 110. By installing the deoxygenated water supply pump 110, it can be ensured that the deoxygenated water in the deoxygenated water pipeline is pressurized and sent into the molten salt exothermic generator 107.

[0042] This invention also relates to an operation method for a flexible peak-shaving and frequency regulation system for a coal-fired power generating unit, characterized in that:

[0043] Energy storage phase operation method:

[0044] When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2, the electrode boiler 203, the water supply pump 202, and the main steam control valve 101 are opened at the same time.

[0045] Electrode boiler 203 consumes the electrical energy generated by the generator to heat the makeup water in makeup water tank 201 into saturated steam and then send it into steam storage tank 204 to reduce the output power of coal-fired power unit to Ws3.

[0046] The low-temperature molten salt in the low-temperature molten salt storage tank 109 is transported to the molten salt heater 102 by the high-temperature molten salt pump 103. In the molten salt heater 102, the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank 104 for storage. The main steam after heat exchange is sent to the boiler feedwater.

[0047] When the output power of the coal-fired power unit drops to Ws4, the electrode boiler 203 and the water supply pump 202 are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank 104 is used for deep peak shaving to Ws2.

[0048] Operation method of the energy release stage:

[0049] At the same time, the outlet valve of the steam storage tank 204 and the No. 1 low-temperature molten salt pump 106 are opened. The saturated steam in the steam storage tank 204 is heated to superheated steam by the high-temperature molten salt after passing through the steam generator 105. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity.

[0050] When the outlet pressure of steam storage tank 204 drops to n times the maximum working pressure, close the outlet valve of steam storage tank 204, and turn on deoxygenated water supply pump 110 and No. 2 low temperature molten salt pump 108 to continue to increase the load by heating the deoxygenated water with high temperature molten salt.

[0051] Preferably, Ws3 is 1.2-1.5 times Ws2, Ws4 is 1.1-1.2 times Ws2, and n takes the value of 0.2-0.5.

[0052] Example 1:

[0053] Energy storage phase operation method:

[0054] When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2 (i.e., the coal-fired power unit needs to store power of Ws1-Ws2), the electrode boiler 203, the water supply pump 202, and the main steam control valve 101 are opened at the same time.

[0055] Electrode boiler 203 consumes the electrical energy generated by the generator to heat the makeup water in makeup water tank 201 into saturated steam and then send it into steam storage tank 204, reducing the output power of coal-fired power unit to 1.2Ws2;

[0056] The low-temperature molten salt in the low-temperature molten salt storage tank 109 is transported to the molten salt heater 102 by the high-temperature molten salt pump 103. In the molten salt heater 102, the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank 104 for storage. The main steam after heat exchange is sent to the boiler feedwater.

[0057] When the output power of the coal-fired power unit drops to 1.1Ws2, the electrode boiler 203 and the water supply pump 202 are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank 104 is used for deep peak shaving to Ws2.

[0058] Operation method of the energy release stage:

[0059] At the same time, the outlet valve of the steam storage tank 204 and the No. 1 low-temperature molten salt pump 106 are opened. The saturated steam in the steam storage tank 204 is heated to superheated steam by the high-temperature molten salt after passing through the steam generator 105. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity.

[0060] When the outlet pressure of steam storage tank 204 drops to 0.2 times the maximum working pressure, close the outlet valve of steam storage tank 204, and turn on deoxygenated water supply pump 110 and No. 2 low temperature molten salt pump 108 to continue to increase the load by heating the deoxygenated water with high temperature molten salt.

[0061] Example 2:

[0062] Energy storage phase operation method:

[0063] When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2 (i.e., the coal-fired power unit needs to store power of Ws1-Ws2), the electrode boiler 203, the water supply pump 202, and the main steam control valve 101 are opened at the same time.

[0064] Electrode boiler 203 consumes the electrical energy generated by the generator to heat the makeup water in makeup water tank 201 into saturated steam and then send it into steam storage tank 204, reducing the output power of coal-fired power unit to 1.3Ws2;

[0065] The low-temperature molten salt in the low-temperature molten salt storage tank 109 is transported to the molten salt heater 102 by the high-temperature molten salt pump 103. In the molten salt heater 102, the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank 104 for storage. The main steam after heat exchange is sent to the boiler feedwater.

[0066] When the output power of the coal-fired power unit drops to 1.1Ws2, the electrode boiler 203 and the water supply pump 202 are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank 104 is used for deep peak shaving to Ws2.

[0067] Operation method of the energy release stage:

[0068] At the same time, the outlet valve of the steam storage tank 204 and the No. 1 low-temperature molten salt pump 106 are opened. The saturated steam in the steam storage tank 204 is heated to superheated steam by the high-temperature molten salt after passing through the steam generator 105. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity.

[0069] When the outlet pressure of steam storage tank 204 drops to 0.2 times the maximum working pressure, close the outlet valve of steam storage tank 204, and turn on deoxygenated water supply pump 110 and No. 2 low temperature molten salt pump 108 to continue to increase the load by heating the deoxygenated water with high temperature molten salt.

[0070] Example 3:

[0071] Energy storage phase operation method:

[0072] When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2 (i.e., the coal-fired power unit needs to store power of Ws1-Ws2), the electrode boiler 203, the water supply pump 202, and the main steam control valve 101 are opened at the same time.

[0073] Electrode boiler 203 consumes the electrical energy generated by the generator to heat the makeup water in makeup water tank 201 into saturated steam and then send it into steam storage tank 204, reducing the output power of coal-fired power unit to 1.5Ws2.

[0074] The low-temperature molten salt in the low-temperature molten salt storage tank 109 is transported to the molten salt heater 102 by the high-temperature molten salt pump 103. In the molten salt heater 102, the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank 104 for storage. The main steam after heat exchange is sent to the boiler feedwater.

[0075] When the output power of the coal-fired power unit drops to 1.1Ws2, the electrode boiler 203 and the water supply pump 202 are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank 104 is used for deep peak shaving to Ws2.

[0076] Operation method of the energy release stage:

[0077] At the same time, the outlet valve of the steam storage tank 204 and the No. 1 low-temperature molten salt pump 106 are opened. The saturated steam in the steam storage tank 204 is heated to superheated steam by the high-temperature molten salt after passing through the steam generator 105. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity.

[0078] When the outlet pressure of steam storage tank 204 drops to 0.2 times the maximum working pressure, close the outlet valve of steam storage tank 204, and turn on deoxygenated water supply pump 110 and No. 2 low temperature molten salt pump 108 to continue to increase the load by heating the deoxygenated water with high temperature molten salt.

[0079] Example 4:

[0080] Energy storage phase operation method:

[0081] When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2 (i.e., the coal-fired power unit needs to store power of Ws1-Ws2), the electrode boiler 203, the water supply pump 202, and the main steam control valve 101 are opened at the same time.

[0082] Electrode boiler 203 consumes the electrical energy generated by the generator to heat the makeup water in makeup water tank 201 into saturated steam and then send it into steam storage tank 204, reducing the output power of coal-fired power unit to 1.3Ws2;

[0083] The low-temperature molten salt in the low-temperature molten salt storage tank 109 is transported to the molten salt heater 102 by the high-temperature molten salt pump 103. In the molten salt heater 102, the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank 104 for storage. The main steam after heat exchange is sent to the boiler feedwater.

[0084] When the output power of the coal-fired power unit drops to 1.15Ws2, the electrode boiler 203 and the water supply pump 202 are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank 104 is used for deep peak shaving to Ws2.

[0085] Operation method of the energy release stage:

[0086] At the same time, the outlet valve of the steam storage tank 204 and the No. 1 low-temperature molten salt pump 106 are opened. The saturated steam in the steam storage tank 204 is heated to superheated steam by the high-temperature molten salt after passing through the steam generator 105. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity.

[0087] When the outlet pressure of steam storage tank 204 drops to 0.2 times the maximum working pressure, close the outlet valve of steam storage tank 204, and turn on deoxygenated water supply pump 110 and No. 2 low temperature molten salt pump 108 to continue to increase the load by heating the deoxygenated water with high temperature molten salt.

[0088] Example 5:

[0089] Energy storage phase operation method:

[0090] When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2 (i.e., the coal-fired power unit needs to store power of Ws1-Ws2), the electrode boiler 203, the water supply pump 202, and the main steam control valve 101 are opened at the same time.

[0091] Electrode boiler 203 consumes the electrical energy generated by the generator to heat the makeup water in makeup water tank 201 into saturated steam and then send it into steam storage tank 204, reducing the output power of coal-fired power unit to 1.3Ws2;

[0092] The low-temperature molten salt in the low-temperature molten salt storage tank 109 is transported to the molten salt heater 102 by the high-temperature molten salt pump 103. In the molten salt heater 102, the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank 104 for storage. The main steam after heat exchange is sent to the boiler feedwater.

[0093] When the output power of the coal-fired power unit drops to 1.2Ws2, the electrode boiler 203 and the water supply pump 202 are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank 104 is used for deep peak shaving to Ws2.

[0094] Operation method of the energy release stage:

[0095] At the same time, the outlet valve of the steam storage tank 204 and the No. 1 low-temperature molten salt pump 106 are opened. The saturated steam in the steam storage tank 204 is heated to superheated steam by the high-temperature molten salt after passing through the steam generator 105. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity.

[0096] When the outlet pressure of steam storage tank 204 drops to 0.2 times the maximum working pressure, close the outlet valve of steam storage tank 204, and turn on deoxygenated water supply pump 110 and No. 2 low temperature molten salt pump 108 to continue to increase the load by heating the deoxygenated water with high temperature molten salt.

[0097] Example 6:

[0098] Energy storage phase operation method:

[0099] When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2 (i.e., the coal-fired power unit needs to store power of Ws1-Ws2), the electrode boiler 203, the water supply pump 202, and the main steam control valve 101 are opened at the same time.

[0100] Electrode boiler 203 consumes the electrical energy generated by the generator to heat the makeup water in makeup water tank 201 into saturated steam and then send it into steam storage tank 204, reducing the output power of coal-fired power unit to 1.3Ws2;

[0101] The low-temperature molten salt in the low-temperature molten salt storage tank 109 is transported to the molten salt heater 102 by the high-temperature molten salt pump 103. In the molten salt heater 102, the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank 104 for storage. The main steam after heat exchange is sent to the boiler feedwater.

[0102] When the output power of the coal-fired power unit drops to 1.15Ws2, the electrode boiler 203 and the water supply pump 202 are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank 104 is used for deep peak shaving to Ws2.

[0103] Operation method of the energy release stage:

[0104] At the same time, the outlet valve of the steam storage tank 204 and the No. 1 low-temperature molten salt pump 106 are opened. The saturated steam in the steam storage tank 204 is heated to superheated steam by the high-temperature molten salt after passing through the steam generator 105. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity.

[0105] When the outlet pressure of steam storage tank 204 drops to 0.3 times the maximum working pressure, close the outlet valve of steam storage tank 204, and turn on deoxygenated water supply pump 110 and No. 2 low temperature molten salt pump 108 to continue to increase the load by heating the deoxygenated water with high temperature molten salt.

[0106] Example 7:

[0107] Energy storage phase operation method:

[0108] When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2 (i.e., the coal-fired power unit needs to store power of Ws1-Ws2), the electrode boiler 203, the water supply pump 202, and the main steam control valve 101 are opened at the same time.

[0109] Electrode boiler 203 consumes the electrical energy generated by the generator to heat the makeup water in makeup water tank 201 into saturated steam and then send it into steam storage tank 204, reducing the output power of coal-fired power unit to 1.3Ws2;

[0110] The low-temperature molten salt in the low-temperature molten salt storage tank 109 is transported to the molten salt heater 102 by the high-temperature molten salt pump 103. In the molten salt heater 102, the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank 104 for storage. The main steam after heat exchange is sent to the boiler feedwater.

[0111] When the output power of the coal-fired power unit drops to 1.15Ws2, the electrode boiler 203 and the water supply pump 202 are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank 104 is used for deep peak shaving to Ws2.

[0112] Operation method of the energy release stage:

[0113] At the same time, the outlet valve of the steam storage tank 204 and the No. 1 low-temperature molten salt pump 106 are opened. The saturated steam in the steam storage tank 204 is heated to superheated steam by the high-temperature molten salt after passing through the steam generator 105. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity.

[0114] When the outlet pressure of steam storage tank 204 drops to 0.5 times the maximum working pressure, close the outlet valve of steam storage tank 204, and turn on deoxygenated water supply pump 110 and No. 2 low temperature molten salt pump 108 to continue to increase the load by heating the deoxygenated water with high temperature molten salt.

[0115] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flexible peak-shaving and frequency regulation system for a coal-fired power generating unit, characterized in that, include: The molten salt heater (102) has its steam inlet end connected to the main steam pipeline of the coal-fired power generation system and its steam outlet end connected to the boiler drain pipeline. The outlet end of the low-temperature molten salt storage tank (109) is connected to the molten salt inlet end of the molten salt heater (102); A high-temperature molten salt storage tank (104) has its inlet end connected to the molten salt outlet end of a molten salt heater (102); The steam generator (105) has its molten salt inlet end connected to the outlet end of the high-temperature molten salt storage tank (104), its molten salt outlet end connected to the inlet end of the low-temperature molten salt storage tank (109), and its steam outlet end connected to the reheat steam pipeline. The steam storage tank (204) has its inlet end connected to the steam outlet end of the electrode boiler (203), the inlet end of the electrode boiler (203) is connected to the water supply tank (201), and its outlet end is connected to the steam inlet end of the steam generator (105). The molten salt exothermic device (107) has its molten salt outlet end connected to the inlet end of the low-temperature molten salt storage tank (109), its molten salt inlet end connected to the outlet end of the high-temperature molten salt storage tank (104), its water-side outlet end connected to the boiler feedwater pipeline, and its water-side inlet end connected to the deoxygenated water pipeline.

2. The flexible peak-shaving and frequency regulation system for coal-fired power generating units according to claim 1, characterized in that: The steam inlet of the molten salt heater (102) is connected to the main steam pipeline of the coal-fired power generation system via the main steam control valve (101).

3. The flexible peak-shaving and frequency regulation system for coal-fired power generating units according to claim 1, characterized in that: The inlet of the high-temperature molten salt storage tank (104) is connected to the molten salt outlet of the molten salt heater (102) via a high-temperature molten salt pump (103).

4. The flexible peak-shaving and frequency regulation system for coal-fired power generating units according to claim 1, characterized in that: The molten salt outlet of the steam generator (105) is connected to the inlet of the cryogenic molten salt storage tank (109) via the No. 1 cryogenic molten salt pump (106).

5. The flexible peak-shaving and frequency regulation system for coal-fired power generating units according to claim 1, characterized in that: The inlet end of the electrode boiler (203) is connected to the water supply tank (201) via a water supply pump (202).

6. The flexible peak-shaving and frequency regulation system for coal-fired power generating units according to claim 1, characterized in that: The molten salt outlet of the molten salt exothermic device (107) is connected to the inlet of the cryogenic molten salt storage tank (109) via a cryogenic molten salt pump (108).

7. The flexible peak-shaving and frequency regulation system for coal-fired power generating units according to claim 1, characterized in that: The water-side inlet of the molten salt exothermic device (107) is connected to the deoxygenated water pipeline via a deoxygenated water supply pump (110).

8. A method for operating a flexible peak-shaving and frequency regulation system for a coal-fired power generating unit according to any one of claims 1-7, characterized in that: Energy storage phase operation method: When the output power of the coal-fired power unit is Ws1, and the power grid requires the coal-fired power unit to reduce its output power to Ws2, the electrode boiler (203), the water supply pump (202), and the main steam control valve (101) are opened simultaneously. The electrode boiler (203) consumes the electrical energy generated by the generator, heats the water in the water tank (201) into saturated steam and sends it into the steam storage tank (204), thereby reducing the output power of the coal-fired power unit to Ws3; The low-temperature molten salt in the low-temperature molten salt storage tank (109) is transported to the molten salt heater (102) by the high-temperature molten salt pump (103). In the molten salt heater (102), the main steam transported by the main steam pipeline of the coal-fired power generation system heats the low-temperature molten salt into high-temperature molten salt and then sends it to the high-temperature molten salt storage tank (104) for storage. The main steam after heat exchange is sent to the boiler feedwater. When the output power of the coal-fired power unit drops to Ws4, the electrode boiler (203) and the water supply pump (202) are shut down, and the molten salt heat storage in the high-temperature molten salt storage tank (104) is used for deep peak shaving to Ws2. Operation method of the energy release stage: At the same time, the outlet valve of the steam storage tank (204) and the No. 1 low-temperature molten salt pump (106) are opened. The saturated steam in the steam storage tank (204) flows through the steam generator (105) and is heated to superheated steam by the high-temperature molten salt. The superheated steam is input into the reheat steam pipeline to increase the unit's work capacity. When the outlet pressure of the steam storage tank (204) drops to n times the maximum working pressure, close the outlet valve of the steam storage tank (204), turn on the deoxygenated water supply pump (110) and the No. 2 low temperature molten salt pump (108), and use the high temperature molten salt to heat the deoxygenated water to continue to increase the load.

9. The operation method of the flexible peak-shaving and frequency regulation system for coal-fired power generating units according to claim 8, characterized in that: Ws3 is 1.2-1.5 times Ws2, Ws4 is 1.1-1.2 times Ws2, and n takes the value of 0.2-0.5.

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