Molten salt energy storage and heat release system for thermal power plants

Abstract

The present invention relates to a molten salt energy storage and heat release system for a thermal power plant. The molten salt energy storage and heat release system includes a steam generation system, a water supply system, a steam return system, and a molten salt system. The water supply system is connected to the steam generation system, and the water in the water supply system is fed into the steam generation system; the molten salt system is connected to the steam generation system, and the high-temperature molten salt in the molten salt system is fed into the steam generation system; the steam generation system is connected to the steam return system, and the steam generated by the steam generation system enters the steam return system and is then fed into the corresponding steam extraction system of the thermal power plant. The molten salt steam generation system converts the original power plant deaerator water or high-pressure outlet water into high-parameter steam and feeds it back to the original power plant unit steam extraction system for power generation. The heat release system fully utilizes the original power plant system equipment to generate low-loss steam, which is fed into the steam extraction system, especially the first-stage steam extraction system, to achieve higher circulation efficiency.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a molten salt energy storage and heat release system for a thermal power plant. Background Art

[0002] In the field of peak-shaving technology for thermal power units, domestic scholars have proposed molten salt heat storage technology for thermal power plants. Chinese patent CN 107401430 A discloses a "heat storage system for dual peak-shaving of electricity and heat in thermal power plants." During the day, steam extraction from the steam turbine is used to heat the molten salt and store the heat energy. At night, when the unit's heating capacity is insufficient, the molten salt is used to release heat for heating. Chinese patent CN 108316980 A discloses a "molten salt heat storage and release peak-shaving system for thermal power units." It extracts some high-temperature reheat steam from the boiler reheater outlet, exchanges heat with the molten salt in the molten salt heat storage system, and completes molten salt heat storage. During heat release, the exhaust steam from the original power plant's high-pressure cylinder is exchanged with the molten salt to generate high-temperature steam that is sent to the medium-pressure cylinder to perform work. Chinese patent CN 106885232 A discloses a "liquid energy storage system suitable for deep peak shaving of thermal power units." This system uses either high-pressure main steam or high-temperature reheat steam to heat a molten salt system for heat storage. The released steam then returns to the turbine for power generation or to the boiler for reheating. Chinese patent CN 108534576 A discloses a "molten salt energy storage system for power peak shaving of thermal power units." This system uses steam from the original power plant's extraction system to heat the molten salt for energy storage. During heat release, a molten salt steam generation system and a small steam turbine are deployed, using the stored molten salt heat to drive the small turbine for power generation. Chinese patent CN 110006026 A discloses a "deep peak shaving system for thermal power plants." This system uses superheated steam from the original power plant to heat the molten salt for energy storage. During heat release, a separate molten salt high-pressure heater is deployed, using the molten salt to directly heat the feedwater.

[0003] The current molten salt energy storage and heat release system is limited by the stability of heat load demand when used for heating; when used for medium pressure cylinder steam supply, the steam parameters are relatively low and the work efficiency is also low; when used to heat the original power plant feed water, a new molten salt high-pressure heater is required, and the large heat exchange temperature difference leads to The loss is large. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a molten salt energy storage and heat release system for a thermal power plant. The heat release system fully utilizes the original power plant system equipment, has a simple system, low investment cost, and higher cycle efficiency.

[0005] The technical solution adopted by the present invention is: a molten salt energy storage and heat release system for a thermal power plant, including a steam generation system, a water supply system, a steam return system and a molten salt system, characterized in that: the water supply system is connected to the steam generation system, and the water in the water supply system is fed into the steam generation system; the molten salt system is connected to the steam generation system, and the high-temperature molten salt in the molten salt system is fed into the steam generation system; the steam generation system is connected to the steam return system, and the steam generated by the steam generation system enters the steam return system and is then fed into the corresponding steam extraction system of the thermal power plant.

[0006] Preferably, the steam generation system includes a superheater, an evaporator, a preheater and a low-load preheater; the water supply system takes the deaerator water or the high-pressure heater outlet water of the thermal power plant, sends it to the water supply tank through the water supply pipe, and then enters the steam generation system after being pressurized by the water supply pump, and then enters the low-load preheater, preheater, evaporator and superheater in sequence.

[0007] Furthermore, the steam generated by the steam generation system enters the steam return system, passes through the steam pipeline and the temperature and pressure reducer, and is then sent to the corresponding steam extraction system of the thermal power plant.

[0008] Preferably, the molten salt system includes a high-temperature molten salt tank, a low-temperature molten salt tank, a high-temperature molten salt pump and a temperature-regulating molten salt pump. The high-temperature molten salt pump sends the high-temperature molten salt into the superheater molten salt inlet pipe, and enters the superheater, evaporator and preheater in the steam generation system in sequence. The high-temperature molten salt is converted into low-temperature molten salt after heat exchange and cooling, and returns to the low-temperature molten salt tank.

[0009] Furthermore, the molten salt system also includes a temperature-regulating molten salt pump, which operates when the energy storage and heat release system is started or when the high-temperature molten salt is overheated, and sends the low-temperature molten salt in the low-temperature molten salt tank into the superheater molten salt inlet pipe to achieve the purpose of molten salt temperature regulation.

[0010] The beneficial effect of the present invention is that the original power plant deaerator water or high pressure outlet water is converted into high parameter steam through the molten salt steam generation system and sent back to the original power plant unit extraction system for power generation. The lost steam is sent to the extraction system, especially the first stage extraction system, which has higher circulation efficiency.

[0011] The present invention has the following advantages:

[0012] (1) Make full use of the original power plant system equipment, the system is simple and the investment cost is low.

[0013] (2) Producing high-quality steam and sending it back to the steam extraction system, especially the first stage steam extraction system, can improve the efficiency of heat release and power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the process of the molten salt energy storage and heat release system of a thermal power plant of the present invention;

[0015] Figure numerals: 1. Steam generation system; 1.1. Superheater; 1.2. Evaporator; 1.3. Preheater; 1.4. Low-load preheater; 2. Water supply system; 2.1. Water supply pipe; 2.2. Water supply tank; 2.3. Water supply pump; 3. Steam return system; 3.1. Return steam pipe; 3.2. Temperature and pressure reducer; 4. Molten salt system; 4.1. High-temperature molten salt tank; 4.2. Low-temperature molten salt tank; 4.3. High-temperature molten salt pump; 4.4. Thermostatic molten salt pump. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] like Figure 1 The molten salt energy storage and heat release system for a thermal power plant shown in the figure includes a steam generation system 1, a water supply system 2, a steam return system 3, and a molten salt system 4. The steam generation system 1 is connected to the water supply system 2, the steam return system 3, and the molten salt system 4, respectively, to realize the heat release process of the molten salt energy storage system. The water supply system 2 is connected to the steam generation system 1, and the water in the water supply system 2 is fed into the steam generation system 1; the molten salt system 4 is connected to the steam generation system 1, and the high-temperature molten salt in the molten salt system 4 is fed into the steam generation system 1; the steam generation system 1 is connected to the steam return system 3, and the steam generated by the steam generation system 1 enters the steam return system 3 and is then sent to the corresponding steam extraction system of the thermal power plant.

[0018] Steam generation system 1 comprises superheater 1.1, evaporator 1.2, preheater 1.3, and low-load preheater 1.4. Feedwater system 2 draws deaerator water or high-pressure heater outlet water from the thermal power plant, delivers it via feedwater pipe 2.1 to feedwater tank 2.2, and then, after being pressurized by feedwater pump 2.3, enters steam generation system 1 and, in sequence, flows into low-load preheater 1.4, preheater 1.3, evaporator 1.2, and superheater 1.1. Steam generated by steam generation system 1 enters steam return system 3, passes through steam pipe 3.1 and desuperheater 3.2, and is then delivered to the corresponding steam extraction system of the thermal power plant.

[0019] The molten salt system 4 includes a high-temperature molten salt tank 4.1, a low-temperature molten salt tank 4.2, a high-temperature molten salt pump 4.3 and a temperature-regulating molten salt pump 4.4. The high-temperature molten salt pump 4.3 delivers the high-temperature molten salt into the superheater molten salt inlet pipe 1.11, and then enters the superheater 1.1, evaporator 1.2 and preheater 1.3 in the steam generation system 1 in sequence. After heat exchange and cooling, the high-temperature molten salt becomes low-temperature molten salt and returns to the low-temperature molten salt tank 4.2. The temperature-regulating molten salt pump 4.4 operates when the energy storage and heat release system is started or when the high-temperature molten salt exceeds the temperature, and delivers the low-temperature molten salt in the low-temperature molten salt tank 4.2 into the superheater molten salt inlet pipe 1.11 to achieve the purpose of molten salt temperature regulation.

[0020] The specific exothermic process is:

[0021] The molten salt in high-temperature molten salt tank 4.1 of molten salt system 4 is pumped out by high-temperature molten salt pump 4.3 and delivered to steam generation system 1. When the high-temperature molten salt exceeds the temperature or the heat release system starts, temperature-regulating molten salt pump 4.4 is activated to pump out the molten salt in low-temperature molten salt tank 4.2. The molten salt is mixed with the high-temperature molten salt and then delivered to steam generation system 1. Within steam generation system 1, the molten salt flows sequentially through superheater 1.1, evaporator 1.2, and preheater 1.3 before cooling and returning to low-temperature molten salt tank 4.2 to release heat.

[0022] Feedwater system 2 draws water from the power plant's deaerator and delivers it via feedwater pipe 2.1 to feedwater tank 2.2. The water in feedwater tank 2.2 is pressurized by feedwater pump 2.3 and then fed into steam generation system 1. Within steam generation system 1, the feedwater first enters low-load preheater 1.4, where it is heated by steam from evaporator 1.2. It then mixes with the drain water from low-load preheater 1.4 and flows sequentially through preheater 1.3, evaporator 1.2, and superheater 1.1, transforming into high-parameter steam before flowing to steam return system 3.

[0023] The steam parameters within steam return system 3 are identical to those of the first extraction stage. It can be directly fed via steam pipe 3.1 into the first extraction stage to heat the No. 1 HP heater, reducing the exhaust volume of the original power plant units and increasing their power generation. Excess steam from heating the No. 1 HP heater passes through desuperheater and pressure reducer 3.2, becoming steam with the same extraction parameters as the other steam. This steam is then returned to the corresponding extraction pipeline, similarly reducing the exhaust volume of the original power plant units and increasing their power generation.

[0024] The above illustrates and describes the basic principles and main structural features of the present invention. The present invention is not limited to the above examples. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A molten salt energy storage and heat release system for a thermal power plant, comprising a steam generation system (1), a water supply system (2), a steam return system (3) and a molten salt system (4), characterized in that: The water supply system (2) is connected to the steam generation system (1), and the water in the water supply system (2) is fed into the steam generation system (1); the molten salt system (4) is connected to the steam generation system (1), and the high-temperature molten salt in the molten salt system (4) is fed into the steam generation system (1); the steam generation system (1) is connected to the steam system (3), and the steam generated by the steam generation system (1) enters the steam system (3) and is then fed into the corresponding steam extraction system of the thermal power plant; The steam generation system (1) includes a superheater (1.1), an evaporator (1.2), a preheater (1.3) and a low-load preheater (1.4); the water supply system (2) takes deaerator water or high-pressure outlet water of the thermal power plant, sends it to the water supply tank (2.2) through the water supply pipe (2.1), and then enters the steam generation system (1) after being pressurized by the water supply pump (2.3), and then enters the low-load preheater (1.4), preheater (1.3), evaporator (1.2) and superheater (1.1) in sequence; the steam generated by the steam generation system (1) enters the return steam system (3), passes through the steam pipe (3.1) and the desuperheater (3.2), and is then sent to the corresponding steam extraction system of the thermal power plant; the molten salt system (4) includes a high-pressure A warm molten salt tank (4.1), a low-temperature molten salt tank (4.2), a high-temperature molten salt pump (4.3) and a temperature-regulating molten salt pump (4.4); the high-temperature molten salt pump (4.3) sends the high-temperature molten salt into the superheater molten salt inlet pipe (1.11), and enters the superheater (1.1), the evaporator (1.2) and the preheater (1.3) in the steam generation system (1) in sequence; the high-temperature molten salt is converted into low-temperature molten salt after heat exchange and cooling, and returns to the low-temperature molten salt tank (4.2); the molten salt system (4) also includes a temperature-regulating molten salt pump (4.4); the temperature-regulating molten salt pump (4.4) is operated when the energy storage and heat release system is started or when the high-temperature molten salt is overheated, and sends the low-temperature molten salt in the low-temperature molten salt tank (4.2) into the superheater molten salt inlet pipe (1.11), so as to achieve the purpose of molten salt temperature regulation.

Images